WO2013115124A1 - Detection system and detection apparatus - Google Patents

Detection system and detection apparatus Download PDF

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Publication number
WO2013115124A1
WO2013115124A1 PCT/JP2013/051726 JP2013051726W WO2013115124A1 WO 2013115124 A1 WO2013115124 A1 WO 2013115124A1 JP 2013051726 W JP2013051726 W JP 2013051726W WO 2013115124 A1 WO2013115124 A1 WO 2013115124A1
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WO
WIPO (PCT)
Prior art keywords
circuit
signal
output
signal processing
input
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PCT/JP2013/051726
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French (fr)
Japanese (ja)
Inventor
正徳 四方山
等志 薩田
Original Assignee
シチズンファインテックミヨタ株式会社
シチズンホールディングス株式会社
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Application filed by シチズンファインテックミヨタ株式会社, シチズンホールディングス株式会社 filed Critical シチズンファインテックミヨタ株式会社
Publication of WO2013115124A1 publication Critical patent/WO2013115124A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/08—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of piezoelectric devices, i.e. electric circuits therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
    • G01L23/08—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid operated electrically
    • G01L23/10—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid operated electrically by pressure-sensitive members of the piezoelectric type

Definitions

  • the present invention relates to a detection system that detects a physical quantity and a detection device that detects a physical quantity.
  • a plurality of detection devices that detect pressure, temperature, and the like are mounted in the device. Based on the detection results of these detection devices, a control called ECU (Engine Control Unit) is performed.
  • the device controls the operation of the internal combustion engine.
  • the control device and the detection device are usually an electric wire for supplying power from the control device to the detection device, an electric wire for sending a signal from the detection device to the control device, and a ground between the control device and the detection device. It connects using the electric wire for making it common.
  • Patent Document 1 in an in-vehicle power steering system including an ECU unit and a current sensor unit that detects a current flowing through a current path, a ground of a power supply line that supplies power from the ECU unit to the current sensor unit is disclosed.
  • a technique for detecting a disconnection of a line using a circuit having an N-channel FET and a resistor is described.
  • An object of the present invention is to enable detection of disconnection of an electric wire used for grounding a signal processing circuit, and to reduce noise in an output signal from the signal processing circuit.
  • the detection system of the present invention includes a detection element for detecting a change in physical quantity, a signal processing circuit for processing a detection signal output from the detection element, the detection element and the signal processing circuit, and a grounding body.
  • a detector that includes a housing electrically connected to the housing, and a DC suppression unit that connects the housing and the ground in the signal processing circuit while suppressing energization of a DC current, and the signal in the detection unit
  • a constant voltage supply line for supplying a constant voltage to the processing circuit, an output signal transmission line for transmitting an output signal output from the signal processing unit, and a ground for connecting to the ground in the signal processing circuit Is connected to the detection unit via a wire and is further electrically connected to the grounding body to supply the constant voltage to the detection unit and input from the detection unit.
  • a supply / processing units performs processing on the output signal.
  • the detection element is composed of a piezoelectric element that detects pressure using a piezoelectric body, and the signal processing circuit integrates the charge signal input from the piezoelectric element, thereby obtaining the charge signal.
  • the signal processing circuit further includes a power supply circuit that converts the constant voltage input via the constant voltage supply line into a voltage lower than the constant voltage and supplies the voltage to the integrating circuit and the amplifier circuit. It is preferable to provide.
  • the integration circuit and the amplification circuit can be configured to include, for example, an operational amplifier.
  • the direct current suppression unit includes a capacitor. As a result, the DC cutoff circuit can be configured with a simple configuration.
  • the detection apparatus of the present invention includes a detection element that detects a change in physical quantity, a signal processing circuit that processes a detection signal output from the detection element, the detection element, and the signal A housing to which a processing circuit is attached, a constant voltage supply means for supplying a constant voltage to the signal processing circuit, an output signal transmission means for transmitting an output signal output from the signal processing circuit, and the signal A grounding means for connecting to the ground in the processing circuit; and a direct current suppression unit that connects the casing and the ground in the signal processing circuit while suppressing the application of direct current.
  • the present invention it is possible to detect disconnection of an electric wire used for grounding a signal processing circuit and to reduce noise in an output signal from the signal processing circuit.
  • FIG. 1 is a schematic configuration diagram of an internal combustion engine according to an embodiment. It is an enlarged view of the II section of the pressure detection apparatus shown in FIG. It is a schematic block diagram of a pressure detection apparatus.
  • FIG. 4 is a cross-sectional view of the IV-IV part of the pressure detection device shown in FIG. 3. It is an enlarged view of the V section of the pressure detection apparatus shown in FIG. It is an enlarged view of VI part of the pressure detection apparatus shown in FIG.
  • FIG. 1 is a schematic configuration diagram of an internal combustion engine 1 according to the present embodiment.
  • 2 is an enlarged view of the II part of the pressure detection device 5 shown in FIG.
  • the internal combustion engine 1 includes a cylinder block 2 having a cylinder 2a, a piston 3 that reciprocates in the cylinder 2a, a cylinder head 4 that is fastened to the cylinder block 2 and forms a combustion chamber C together with the cylinder 2a, the piston 3, and the like, It has.
  • both the cylinder block 2 and the cylinder head 4 are made of conductive aluminum, cast iron, or the like.
  • the internal combustion engine 1 is mounted on the cylinder head 4 to detect the pressure in the combustion chamber C, and a control device that controls the operation of the internal combustion engine 1 based on the pressure detected by the pressure detection device 5. 6, an electric signal is transmitted between the pressure detection device 5 and the control device 6, and between the pressure detection device 5 and the control device 6, which is interposed between the pressure detection device 5 and the cylinder head 4 and maintains the airtightness in the combustion chamber C.
  • the transmission cable 8 includes three cables, that is, a first cable 81, a second cable 82, and a third cable 83, and the first cable 81 to the third cable 83. And a connector 80 for connecting to the connector.
  • each of the first cable 81, the second cable 82, and the third cable 83 is constituted by an insulated wire in which the outer peripheral surface of a conductor portion made of a tinned annealed copper stranded wire is coated with a resin insulator.
  • the first cable 81 functions as a constant voltage supply line
  • the second cable 82 functions as an output signal transmission line
  • the third cable 83 functions as a ground line.
  • the cylinder head 4 is formed with a communication hole 4a for communicating the combustion chamber C with the outside.
  • the communication hole 4a has a hole diameter larger than the first hole part 4b, the inclined part 4c whose diameter gradually increases from the hole diameter of the first hole part 4b, and the hole diameter of the first hole part 4b.
  • a female screw 4e into which a male screw 332a of the housing 30 (described later) formed in the pressure detection device 5 is screwed is formed on the surrounding wall forming the second hole 4d.
  • FIG. 3 is a schematic configuration diagram of a pressure detection device 5 as an example of a detection unit or a detection device.
  • 4 is a cross-sectional view of the IV-IV portion of the pressure detection device 5 shown in FIG.
  • FIG. 5 is an enlarged view of a V portion of the pressure detection device 5 shown in FIG.
  • FIG. 6 is an enlarged view of a VI part of the pressure detection device 5 shown in FIG.
  • the pressure detection device 5 includes a sensor unit 100 having a piezoelectric element 10 that converts the pressure in the combustion chamber C into an electric signal, a signal processing unit 200 that processes an electric signal from the sensor unit 100, and a signal processing unit 200. Holding member 300.
  • the pressure detection device 5 is mounted on the cylinder head 4, the diaphragm head 40 (described later) of the sensor unit 100 is inserted into the communication hole 4 a formed in the cylinder head 4 first.
  • the left side of FIG. 4 is the front end side of the pressure detection device 5
  • the right side is the rear end side of the pressure detection device 5.
  • the sensor unit 100 includes a piezoelectric element 10 that converts received pressure into an electrical signal, and a housing 30 that is cylindrical and in which a cylindrical hole that accommodates the piezoelectric element 10 and the like is formed. .
  • the center line direction of the cylindrical hole formed in the housing 30 is simply referred to as a center line direction.
  • the sensor unit 100 is provided so as to close the opening on the distal end side of the housing 30, and is provided between the diaphragm head 40 on which the pressure in the combustion chamber C acts, and between the diaphragm head 40 and the piezoelectric element 10.
  • the first electrode unit 50 and the second electrode unit 55 disposed on the opposite side of the piezoelectric element 10 from the first electrode unit 50 are provided.
  • the sensor unit 100 is provided with an insulating ring 60 made of alumina ceramic that electrically insulates the second electrode unit 55 and a rear end side of the insulating ring 60, and a covering member 23 described later of the signal processing unit 200. And a coil spring 70 interposed between the second electrode portion 55 and a conductive member 22 described later.
  • the piezoelectric element 10 has a piezoelectric body that exhibits the piezoelectric action of the piezoelectric longitudinal effect.
  • the piezoelectric longitudinal effect refers to the action of generating charges on the surface of the piezoelectric body in the direction of the charge generation axis when an external force is applied to the stress application axis in the same direction as the charge generation axis of the piezoelectric body.
  • the piezoelectric element 10 according to the present embodiment is housed in the housing 30 so that the center line direction is the direction of the stress application axis.
  • the piezoelectric transverse effect is an action in which charges are generated on the surface of the piezoelectric body in the direction of the charge generation axis when an external force is applied to the stress application axis at a position orthogonal to the charge generation axis of the piezoelectric body.
  • a plurality of thinly formed piezoelectric bodies may be laminated, and by laminating in this way, the charge generated in the piezoelectric bodies can be efficiently collected to increase the sensitivity of the sensor.
  • Examples of the piezoelectric body include the use of a langasite crystal (a langasite, langagate, langanite, LGTA) having a piezoelectric longitudinal effect and a piezoelectric transverse effect, quartz, gallium phosphate, and the like.
  • a langasite single crystal is used as the piezoelectric body.
  • the housing 30 as an example of the housing includes a first housing 31 provided on the front end side and a second housing 32 provided on the rear end side.
  • the first housing 31 is a thin-walled cylindrical member having a cylindrical hole 310 formed therein so as to have a diameter that gradually changes from the front end side to the rear end side.
  • a projecting portion 315 that protrudes from the outer peripheral surface is provided in the central portion in the center line direction over the entire region in the circumferential direction.
  • the hole 310 includes a first hole 311 and a second hole 312 having a diameter larger than the diameter of the first hole 311 formed in order from the front end side to the rear end side.
  • the protrusion 315 has an inclined surface 315a whose diameter gradually increases from the front end side to the rear end side at the front end portion, and a vertical surface 315b perpendicular to the center line direction at the rear end portion.
  • the second housing 32 is a cylindrical member in which a cylindrical hole 320 is formed so that the diameter gradually changes from the front end side to the rear end side.
  • An outer peripheral surface 330 is formed on the outside so that the diameter is gradually changed from the front end side to the rear end side.
  • the hole 320 includes a first cylindrical hole 321 having a first hole diameter, a second cylindrical hole 322 having a second hole diameter smaller than the first hole diameter, and a second hole diameter.
  • a third cylindrical hole 323 having a larger third hole diameter, a fourth cylindrical hole 324 having a fourth hole diameter larger than the third hole diameter, a fifth cylindrical hole 325 having a fifth hole diameter larger than the fourth hole diameter, Consists of The first hole diameter in the first cylindrical hole 321 is such that the front end of the second housing 32 is fitted (press-fit) to the rear end of the first housing 31 with an interference fit. It is set to be less than the diameter.
  • the outer peripheral surface 330 has a first outer peripheral surface 331, a second outer peripheral surface 332 having an outer diameter larger than the outer diameter of the first outer peripheral surface 331, and an outer diameter of the second outer peripheral surface 332 from the front end side to the rear end side.
  • a third outer peripheral surface 333 having a larger outer diameter
  • a fourth outer peripheral surface 334 having an outer diameter larger than the outer diameter of the third outer peripheral surface 333
  • a fifth outer periphery having an outer diameter smaller than the outer diameter of the fourth outer peripheral surface 334
  • a male screw 332 a that is screwed into the female screw 4 e of the cylinder head 4 is formed at the tip of the second outer peripheral surface 332.
  • a first seal member 71 which will be described later, is fitted into the third outer peripheral surface 333 with a clearance fit, and the dimensional tolerance between the outer diameter of the third outer peripheral surface 333 and the inner diameter of the first seal member 71 is, for example, from zero to 0.2 mm.
  • the rear end portion of the fourth outer peripheral surface 334 is formed as a regular hexagonal column having six chamfers at equal intervals in the circumferential direction.
  • the portion formed in the regular hexagonal column is a portion into which a tightening tool is fitted and a rotational force applied to the tool is transmitted.
  • a concave portion 335a that is recessed from the outer peripheral surface is formed over the entire circumference in the center portion of the fifth outer peripheral surface 335 in the center line direction.
  • the second housing 32 is a transition portion from the fourth cylindrical hole 324 to the fifth cylindrical hole 325, and a signal is placed at the tip of the fifth cylindrical hole 325 (see FIG. 4).
  • An abutting surface 340 against which an end surface on the front end side of the substrate covering portion 232 of the covering member 23 described later of the processing unit 200 abuts is provided.
  • the abutting surface 340 is formed with a pin recess 340a into which the input-side second connection pin 21b of the circuit board unit 21 in the signal processing unit 200 described later is inserted.
  • first housing 31 and the second housing 32 exist at a position close to the combustion chamber C, it is desirable to manufacture the first housing 31 and the second housing 32 using a material that can withstand at least an operating temperature environment of ⁇ 40 to 350 [° C.]. Moreover, since the 1st housing 31 and the 2nd housing 32 are used for the earthing
  • the diaphragm head 40 has a cylindrical cylindrical portion 41 and an inner portion 42 formed inside the cylindrical portion 41.
  • the rear end portion of the cylindrical portion 41 is fitted (press-fitted) with the front end portion of the first housing 31 of the housing 30 with an interference fit, and enters the inside of the front end portion, and the end surface 31a at the front end portion.
  • the inner part 42 is a disk-shaped member provided so as to close the opening on the front end side in the cylindrical part 41, and a protruding part that protrudes from this surface to the piezoelectric element 10 side in the central part on the rear end side surface 42a is provided.
  • a concave portion 42b that is recessed from this surface to the piezoelectric element 10 side is provided at the center of the inner portion 42 on the front end side surface.
  • the material of the diaphragm head 40 is preferably made of an alloy having high elasticity and excellent durability, heat resistance, touch resistance, and the like because it exists in the combustion chamber C at a high temperature and a high pressure.
  • SUH660 can be illustrated.
  • the first electrode portion 50 is a columnar member formed so as to have a stepwise difference in diameter from the front end side to the rear end side, and has a radius larger than the radius of the first columnar portion 51 and the first columnar portion 51.
  • the second cylindrical portion 52 The outer diameter of the first cylindrical portion 51 is smaller than the inner diameter of the entry portion 41 a of the diaphragm head 40, and the outer diameter of the second cylindrical portion 52 is substantially the same as the hole diameter of the first hole 311 of the first housing 31.
  • the end surface on the front end side of the first cylindrical portion 51 is in contact with the protruding portion 42 a of the inner side portion 42 of the diaphragm head 40, and the end surface on the rear end side of the second cylindrical portion 52 is in contact with the front surface side of the piezoelectric element 10.
  • the outer peripheral surface of the second cylindrical portion 52 is in contact with the inner peripheral surface of the first housing 31 and / or the end surface on the distal end side of the first cylindrical portion 51 is in contact with the diaphragm head 40, the distal end of the piezoelectric element 10 is obtained.
  • the part is electrically connected to the housing 30.
  • the first electrode portion 50 applies pressure in the combustion chamber C to the piezoelectric element 10, and the end surface on the rear end side of the second cylindrical portion 52, which is the end surface on the piezoelectric element 10 side, is the end surface of the piezoelectric element 10. It is formed in a size that can push the entire surface.
  • the first electrode portion 50 has both end surfaces in the center line direction formed as smooth surfaces so that the pressure received from the diaphragm head 40 can be applied to the piezoelectric element 10 evenly, and the first electrode portion 50 has a center line direction.
  • An example of the material of the first electrode unit 50 is stainless steel.
  • the second electrode portion 55 is a columnar member, and is disposed such that the end surface on the front end side is in contact with the end surface on the rear end side in the piezoelectric element 10 and the end surface on the rear end side is in contact with the insulating ring 60.
  • a columnar projecting portion 55 a that projects from the end surface to the rear end side is provided on the end surface on the rear end side of the second electrode portion 55.
  • the protrusion 55a has a base end portion on the end face side and a tip end portion having an outer diameter smaller than the outer diameter of the base end portion.
  • the outer diameter of the protruding portion 55a is set smaller than the inner diameter of the insulating ring 60, and the length of the protruding portion 55a is set longer than the width of the insulating ring 60 (the length in the center line direction).
  • the tip is exposed from the insulating ring 60.
  • the second electrode portion 55 is a member that acts to apply a constant load to the piezoelectric element 10 between the second electrode portion 50 and the end face on the piezoelectric element 10 side (tip side) is a piezoelectric element.
  • 10 is formed to have a size capable of pressing the entire end face on the rear end side of the surface 10 and a flat surface parallel to the end face on the rear end side of the piezoelectric element 10.
  • the outer diameter of the second electrode portion 55 is set to be smaller than the hole diameter of the second hole 312 of the first housing 31, and the outer peripheral surface of the second electrode portion 55 and the inner peripheral surface of the first housing 31 are set. There is a gap between them.
  • An example of the material of the second electrode portion 55 is stainless steel.
  • the insulating ring 60 is a cylindrical member formed of alumina ceramic or the like, and the inner diameter (hole diameter at the center) is slightly larger than the outer diameter of the base end portion of the protruding portion 55a of the second electrode portion 55.
  • the diameter is set to be substantially the same as the hole diameter of the second hole 312 of the first housing 31.
  • the second electrode portion 55 is disposed with the protruding portion 55a inserted into the central hole of the insulating ring 60, so that the center position of the second electrode portion 55 and the center of the second hole 312 of the first housing 31 are Are arranged to be the same.
  • the support member 65 is a cylindrical member in which a plurality of cylindrical holes 650 having different diameters are formed inside from the front end side to the rear end side, and the diameter of the outer peripheral surface is the same.
  • the holes 650 are formed in order from the front end side to the rear end side, and have a first hole 651, a second hole 652 having a diameter larger than the diameter of the first hole 651, and a diameter larger than the diameter of the second hole 652.
  • the diameter of the first hole 651 is larger than the outer diameter of the base end portion of the protruding portion 55 a of the second electrode portion 55, and the protruding portion 55 a is exposed to the inside of the support member 65.
  • the hole diameter of the second hole 652 is larger than the outer diameter of the distal end portion of the conductive member 22 of the signal processing unit 200 described later.
  • the hole diameter of the third hole 653 is smaller than the outer diameter of the end portion on the front end side of the covering member 23 of the signal processing unit 200 described later, and the covering member 23 is fitted to the surrounding wall forming the third hole 653. Mated.
  • the support member 65 functions as a member that supports the end portion of the covering member 23.
  • the coil spring 70 has an inner diameter that is equal to or larger than the outer diameter of the distal end portion of the protruding portion 55a of the second electrode portion 55 and smaller than the outer diameter of the proximal end portion, and the outer diameter is smaller than the diameter of the insertion hole 22a of the conductive member 22 described later. Is also small.
  • the distal end portion of the protruding portion 55a of the second electrode portion 55 is inserted inside the coil spring 70, and the coil spring 70 is inserted into an insertion hole 22a of the conductive member 22 described later.
  • the length of the coil spring 70 is set to a length that can be interposed in a compressed state between the second electrode portion 55 and the conductive member 22.
  • As a material of the coil spring 70 an alloy having high elasticity and excellent durability, heat resistance, touch resistance and the like may be used. Further, it is preferable to increase electrical conduction by applying gold plating to the surface of the coil spring 70.
  • the signal processing unit 200 is generated in the piezoelectric element 10 and the circuit board unit 21 that at least amplifies an electric signal that is a weak charge obtained from the piezoelectric element 10 of the sensor unit 100.
  • a rod-shaped conductive member 22 that guides electric charges to the circuit board portion 21, a cover member 23 that covers the circuit board portion 21, the conductive member 22, and the like, and an O-ring 26 that seals the circuit board portion 21 and the like are provided.
  • the circuit board unit 21 includes a mounting board 210 on which electronic components constituting a circuit for amplifying a weak charge obtained from the piezoelectric element 10 of the sensor unit 100 are mounted.
  • An input side first connection pin 21a for electrically connecting a rear end portion of the conductive member 22 and an input side second connection pin 21b for grounding and positioning are soldered to the front end portion of the mounting substrate 210. Connected by attaching.
  • an output side first connection pin 21 c for electrically connecting to the control device 6 via a connector 80 provided at the front end portion of the transmission cable 8, an output side second portion.
  • the connection pin 21d and the output side third connection pin 21e are connected by soldering or the like.
  • the output-side first connection pin 21c is used to supply a power supply voltage (external power supply voltage Vc described later) from the control device 6 to the mounting board 210, and the output-side second connection pin 21d is controlled from the mounting board 210.
  • the output side third connection pin 21e is used for supplying a GND voltage from the control device 6 to the mounting board 210.
  • the output side third connection pin 21e is used for supplying an output voltage (external output voltage Vo described later) to the device 6.
  • the conductive member 22 is a rod-shaped (columnar) member, and an insertion hole 22a into which the distal end portion of the protruding portion 55a of the second electrode portion 55 is inserted is formed at the distal end portion.
  • the rear end portion of the conductive member 22 is electrically connected to the mounting substrate 210 of the circuit board portion 21 via a conductive wire (not shown) and the input-side first connection pin 21a.
  • Examples of the material of the conductive member 22 include brass and beryllium copper. In this case, brass is desirable from the viewpoint of workability and cost. On the other hand, beryllium copper is desirable from the viewpoints of electrical conductivity, high temperature strength, and reliability.
  • the covering member 23 includes a conductive member covering portion 231 that covers the outer periphery of the conductive member 22, a substrate covering portion 232 that covers the side surface and the bottom surface of the mounting substrate 210 of the circuit board portion 21, and a first output side connected to the mounting substrate 210. And a connector portion 233 that covers the periphery of the connection pin 21c, the output-side second connection pin 21d, and the output-side third connection pin 21e, and into which the connector 80 provided at the distal end portion of the transmission cable 8 is fitted.
  • the conductive member covering portion 231 extends along the center line direction and covers the conductive member 22 so that the distal end portion is exposed. Further, the conductive member covering portion 231 is composed of a plurality of cylindrical portions so that the outer diameters are gradually changed from the front end side to the rear end side. Specifically, a first cylindrical portion 241 having a first outer diameter, a second cylindrical portion 242 having a second outer diameter smaller than the first outer diameter, and a second outer diameter from the front end side to the rear end side. A third cylindrical portion 243 having a larger third outer diameter and a fourth cylindrical portion 244 having a fourth outer diameter larger than the third outer diameter are formed side by side.
  • the first outer diameter of the first cylindrical portion 241 is formed larger than the hole diameter of the third hole 653 of the support member 65. As a result, the leading end of the conductive member covering portion 231 is fitted (press-fitted) into the surrounding wall forming the third hole 653 of the support member 65 with an interference fit.
  • the conductive member covering portion 231 is provided with a plurality of convex portions 250 that protrude from the outer peripheral surface of the conductive member covering portion 231 and each extend in the center line direction.
  • the convex portion 250 is provided on the first convex portion 251 provided at the distal end portion of the second cylindrical portion 242 of the conductive member covering portion 231 and the fourth cylindrical portion 244 provided on the conductive member covering portion 231.
  • Two convex portions 252 are provided.
  • four first convex portions 251 are provided on the outer peripheral surface of the second cylindrical portion 242 at intervals of 90 degrees along the circumferential direction.
  • four second convex portions 252 are provided at intervals of 90 degrees along the circumferential direction on the outer peripheral surface of the fourth cylindrical portion 244.
  • the four first convex portions 251 are formed integrally with the second cylindrical portion 242 in the conductive member covering portion 231, and the four second convex portions 252 are formed in the conductive member covering portion 231. It is integrally formed with the fourth cylindrical portion 244.
  • the four first convex portions 251 provided in the second cylindrical portion 242 respectively contact the wall forming the second cylindrical hole 322 in the second housing 32. Touch.
  • the plurality of second convex portions 252 provided in the fourth cylindrical portion 244 abuts against the wall forming the fourth cylindrical hole 324 in the second housing 32.
  • the conductive member covering portion 231 is supported by the second housing 32.
  • the substrate covering portion 232 is basically a cylindrical portion, and a rectangular opening 232a for installing the mounting substrate 210 therein is provided on the side surface thereof.
  • a ring groove 232b for the O-ring 26 for sealing the inside of the housing 30 and the mounting board 210 installation portion is formed on the rear end side of the substrate covering portion 232.
  • the connector part 233 protrudes from the end face 232c on the rear end side in the board covering part 232, and is connected to the output side first connection pin 21c, the output side second connection pin 21d, and the output side third connection pin 21e connected to the mounting board 210. It is a thin part formed so as to cover the periphery.
  • the rear end portion of the connector portion 233 is open so that the connector 80 provided at the front end portion of the transmission cable 8 can be received therein. Further, a hole 233a that connects the inside and the outside is formed on the rear end side of the connector portion 233, and a hook provided on the connector 80 of the transmission cable 8 is hooked on the hole 233a, so that the transmission cable The eight connectors 80 are prevented from dropping from the connector portion 233.
  • the covering member 23 configured as described above is formed of an insulating material such as resin. Further, the covering member 23 includes the conductive member 22, the input side first connection pin 21a, the input side second connection pin 21b, the output side first connection pin 21c, the output side second connection pin 21d, and the output side third connection pin 21e. It is integrally molded with it. More specifically, the covering member 23 includes the conductive member 22, the input side first connection pin 21a, the input side second connection pin 21b, the output side first connection pin 21c, the output side second connection pin 21d, and the output side. Molded by pressing the heated resin into the mold on which the third connection pin 21e is set.
  • the mounting substrate 210 of the circuit board unit 21 is inserted from the opening 232 a of the formed covering member 23 and installed at the center of the substrate covering unit 232.
  • the input side first connection pin 21a, the input side second connection pin 21b, the output side first connection pin 21c, and the output side second connection pin 21d are inserted into the through holes penetrating in the plate thickness direction.
  • each tip of the output side third connection pin 21e is passed through and soldered.
  • the input side 1st connection pin 21a and the conduction member 22 are connected using a conducting wire.
  • the O-ring 26 is attached to the ring groove 232 b of the substrate covering portion 232 of the covering member 23.
  • the O-ring 26 is a well-known O-shaped ring made of fluorine-based rubber.
  • the holding member 300 is a thin cylindrical member, and as shown in FIG. 4, a protruding portion 300 a that protrudes inward from the inner peripheral surface is provided at the rear end portion.
  • the holding member 300 is caulked by pressurizing a portion corresponding to the concave portion 335 a provided in the fifth outer peripheral surface 335 from the outside. Thereby, the holding member 300 becomes difficult to move with respect to the housing 30, and the signal processing unit 200 is prevented from moving with respect to the housing 30.
  • FIG. 7 shows a circuit configuration diagram of the mounting substrate 210.
  • the mounting board 210 of this embodiment includes a printed wiring board 211 on which wiring (circuit pattern) for mounting one or a plurality of electronic components (circuit elements) is formed.
  • the mounting board 210 further includes a protection circuit 212, an integration circuit 213, an amplification circuit 214, a DC cutoff circuit 215, and a power supply circuit (Vreg) 216 mounted on the printed wiring board 211.
  • the integration circuit 213, the amplification circuit 214, and the power supply circuit 216 have a function as a signal processing circuit
  • the DC cutoff circuit 215 has a function as a DC suppression unit.
  • a charge signal as an example of a detection signal input from the piezoelectric element 10 via the protection circuit 212 is converted into a voltage signal by integration by the integration circuit 213, and after the conversion Are amplified by the amplification circuit 214 and output to the outside (for example, the control device 6 shown in FIG. 1).
  • the power supply circuit 216 creates and outputs a power supply voltage (an internal output voltage Vi described later) used in the integration circuit 213 and the amplifier circuit 214.
  • the DC cutoff circuit 215 blocks a DC current from the ground side of the mounting board 210 toward the housing 30 (more specifically, the second housing 32) that is the grounding target of the mounting board 210.
  • a so-called glass epoxy substrate based on a glass cloth base epoxy resin is used as the printed wiring board 211.
  • the printed circuit board 211 is provided with an input signal terminal 211a, an input ground terminal 211b, a power supply terminal 211c, an output signal terminal 211d, and an output ground terminal 211e as input / output terminals.
  • the input signal terminal 211 a is connected to the end face on the rear end side of the piezoelectric element 10 through the input side first connection pin 21 a, the conductive member 22, the coil spring 70, and the second electrode portion 55.
  • the input ground terminal 211b is connected to the second housing 32 via the input-side second connection pin 21b.
  • the power terminal 211c is connected to the first cable 81 (see FIG. 2) via the output-side first connection pin 21c and the connector 80.
  • the output signal terminal 211d is connected to the second cable 82 (see FIG. 2) via the output-side first connection pin 21c and the connector 80.
  • the output ground terminal 211e is connected to the third cable 83 (see FIG. 2) via the output-side third connection pin 21e and the connector 80.
  • the input ground terminal 211b and the output ground terminal 211e are connected to each other via a wiring provided on the printed wiring board 211 and a DC cutoff circuit 215 (capacitor).
  • the protection circuit 212 is composed of a diode, and an anode is connected to the input ground terminal 211b side and a cathode is connected to the power supply terminal 211c side.
  • the integrating circuit 213 includes a first operational amplifier OP1, an integrating capacitor C1, and a feedback resistor R1.
  • the inverting input terminal of the first operational amplifier OP1 is connected to the input signal terminal 211a.
  • the non-inverting input terminal of the first operational amplifier OP1 is connected to the output terminal (out) of the power supply circuit 216.
  • the output terminal of the first operational amplifier OP1 is connected to a non-inverting input terminal of a second operational amplifier OP2 (details will be described later) provided in the amplifier circuit 214.
  • one end of the integrating capacitor C1 is connected to the inverting input terminal of the first operational amplifier OP1, and the other end of the integrating capacitor C1 is connected to the output terminal of the first operational amplifier OP1.
  • One end of the feedback resistor R1 is connected to the inverting input terminal of the first operational amplifier OP1, and the other end of the feedback resistor R1 is connected to the output terminal of the first operational amplifier OP1. Therefore, the integrating capacitor C1 and the feedback resistor R1 are connected in parallel to the inverting input terminal and the output terminal of the first operational amplifier OP1.
  • the amplifier circuit 214 includes a second operational amplifier OP2, a first setting resistor R2a, and a second setting resistor R2b.
  • the inverting input terminal of the second operational amplifier OP2 is connected to the output terminal (out) of the power supply circuit 216 via the first setting resistor R2a.
  • the non-inverting input terminal of the second operational amplifier OP2 is connected to the output terminal of the first operational amplifier OP1 provided in the integrating circuit 213. Further, the output terminal of the second operational amplifier OP2 is connected to the output signal terminal 211d.
  • one end of the second setting resistor R2b is connected to the inverting input terminal of the second operational amplifier OP2, and the other end of the second setting resistor R2b is connected to the output terminal of the second operational amplifier OP2.
  • the DC cut-off circuit 215 is composed of a capacitor, one end is connected to the input ground terminal 211b, and the other end is connected to the anode side of the diode constituting the protection circuit 212.
  • a capacitor having a capacity of 1 ⁇ F is used as the DC cutoff circuit 215.
  • the power supply circuit 216 has an input terminal (in) connected to the power supply terminal 211c and an output terminal (out) connected to the integration circuit 213 (more specifically, the first operational amplifier OP1 provided in the integration circuit 213).
  • a non-inverting input terminal) and an amplifier circuit 214 (more specifically, a first setting resistor R2a provided in the amplifier circuit 214), and a ground terminal (GND) thereof is connected to the output ground terminal 211e, and It is connected to the input ground terminal 211b via the DC cutoff circuit 215.
  • the input charge Qi is input from the piezoelectric element 10 to the input signal terminal 211a as an input signal (charge signal).
  • An external power supply voltage Vc (an example of DC + 5.0 V in this example) is applied from the control device 6 to the power supply terminal 211c.
  • an external output voltage Vo as an example of an output signal is output from the output signal terminal 211 d to the control device 6.
  • the input ground terminal 211b and the output ground terminal 211e are set to the ground potential (GND potential) by being connected to a ground body provided outside the mounting substrate 210, respectively.
  • the integrating circuit 213 integrates the input charge Qi input from the piezoelectric element 10 and outputs the obtained internal output voltage Vi to the amplifying circuit 214. At this time, the input charge Qi is supplied from the input signal terminal 211a to the inverting input terminal of the first operational amplifier OP1. On the other hand, an internal power supply voltage Vr serving as a reference voltage is applied from the power supply circuit 216 to the non-inverting input terminal of the first operational amplifier OP1.
  • the integration circuit 213 of the present embodiment is configured as an integration circuit using the first operational amplifier OP1. However, the non-inverting input terminal of the first operational amplifier OP1 is not set to the GND potential (grounded) but is set to the internal power supply voltage Vr. This is because the first operational amplifier OP1 operates with a single power supply (details will be described later) and that the input charge Qi can take both positive and negative values.
  • the amplifying circuit 214 amplifies the internal output voltage Vi input from the integrating circuit 213, and outputs the obtained external output voltage Vo to the outside (for example, the control device 6 shown in FIG. 1).
  • the internal power supply voltage Vr output from the power supply circuit 216 is applied to the inverting input terminal of the second operational amplifier OP2 via the first setting resistor R2a.
  • the external output voltage Vo output from the output terminal of the second operational amplifier OP2 is applied to the inverting input terminal of the second operational amplifier OP2 via the second setting resistor R2b.
  • the internal output voltage Vi output from the output terminal of the first operational amplifier OP1 in the integrating circuit 213 is applied to the non-inverting input terminal of the second operational amplifier OP2.
  • the amplifier circuit 214 of the present embodiment is configured as an inverting amplifier circuit using the second operational amplifier OP2.
  • the power supply circuit 216 converts the external power supply voltage Vc (DC + 5.0V in this example) input via the power supply terminal 211c into a lower internal power supply voltage Vr (DC + 1.0V in this example) and outputs the converted voltage. Details of the circuit configuration of the power supply circuit 216 will be described later.
  • the first operational amplifier OP1 provided in the integrating circuit 213 and the second operational amplifier OP2 provided in the amplifying circuit 214 are each operated by a single power source of DC + 5.0V.
  • a positive power supply terminal (not shown) is connected to a power supply terminal 211c via a wiring not shown, and a negative power supply terminal (not shown) is connected.
  • the output ground terminal 211e is connected via a wiring (not shown). Therefore, DC + 5.0V is supplied as an operating voltage to each of the first operational amplifier OP1 and the second operational amplifier OP2.
  • FIG. 8 shows a circuit configuration diagram of the power supply circuit 216 provided on the mounting substrate 210.
  • the power supply circuit 216 includes a voltage dividing circuit 2161 for dividing the external output voltage Vo to obtain the internal power supply voltage Vr, and a voltage follower circuit 2162 for stabilizing the obtained internal power supply voltage Vr.
  • the voltage dividing circuit 2161 has one end connected to the input terminal (in) of the power supply circuit 216 and one end connected to the other end of the first voltage dividing resistor R3a and the other end connected to the power supply circuit. And a second voltage dividing resistor R3b connected to the ground terminal (GND) of 216.
  • the external output voltage Vo applied between the input terminal (in) and the ground terminal (GND) of the power supply circuit 216 is dropped by the drop voltage Vd in the first voltage dividing resistor R3a, and
  • the connection end of the first voltage dividing resistor R3a and the second voltage dividing resistor R3b in the voltage dividing circuit 2161 is connected to a non-inverting input terminal of a third operational amplifier OP3 (details will be described later) provided in the voltage follower circuit 2162. Connected.
  • the voltage follower circuit 2162 has a third operational amplifier OP3.
  • the non-inverting input terminal of the third operational amplifier OP3 is connected to the connection end of the voltage dividing circuit 2161.
  • the output terminal of the third operational amplifier OP3 is connected to the output terminal (out) of the power supply circuit 216 and the inverting input terminal of the third operational amplifier OP3.
  • the electrical connection structure in the pressure detection apparatus 5 mentioned above is demonstrated.
  • the end face on the front end side of the piezoelectric element 10 is electrically connected to the metal housing 30 via the metal first electrode portion 50 and the diaphragm head 40.
  • the end surface on the rear end side of the piezoelectric element 10 is electrically connected to the metal second electrode portion 55, and the second electrode portion 55 is connected to the metal coil spring 70 via the protruding portion 55 a. Electrically connected.
  • the coil spring 70 is electrically connected to the metal conductive member 22, and the conductive member 22 is electrically connected to the input signal terminal 211 a of the mounting substrate 210 via the input-side first connection pin 21 a.
  • the outer diameter of the protrusion 55 a of the second electrode portion 55 is smaller than the hole diameter of the first hole 651 of the support member 65, and the outer diameter of the tip portion of the conductive member 22 is larger than the hole diameter of the second hole 652 of the support member 65.
  • the second electrode portion 55, the coil spring 70, and the conductive member 22 are not electrically connected because they are not in direct contact with the support member 65. Therefore, the charge signal transmission path from the second electrode portion 55 to the mounting substrate 210 via the coil spring 70 and the conductive member 22 is formed by the insulating ring 60 and the covering member 23 each made of an insulator. It is electrically insulated from the metal housing 30.
  • the input ground terminal 211b of the mounting substrate 210 is electrically connected to the second housing 32 (housing 30) via the input-side second connection pin 21b.
  • the power supply terminal 211c of the mounting substrate 210 is electrically connected to the first cable 81 via the output-side first connection pin 21c.
  • the output signal terminal 211d of the mounting substrate 210 is electrically connected to the second cable 82 via the output-side second connection pin 21d.
  • the output ground terminal 211e of the mounting substrate 210 is electrically connected to the third cable 83 via the output-side third connection pin 21e.
  • the diaphragm head 40 of the sensor unit 100 is inserted into the communication hole 4a formed in the cylinder head 4 first,
  • the male screw 332 a formed in the second housing 32 of the housing 30 is screwed into the female screw 4 e formed in the communication hole 4 a of the cylinder head 4.
  • the housing 30 is electrically connected to the metal cylinder head 4. Since the cylinder head 4 is in a state of being electrically grounded, in the pressure detection device 5, the tip portion of the piezoelectric element 10 is grounded via the housing 30.
  • the side surface of the piezoelectric element 10 and the inner wall surface of the housing 30 are in contact with each other, but the resistance value is extremely large because the piezoelectric element 10 is made of an insulator.
  • the electric charge generated with the pressure change is generated at both ends of the piezoelectric element 10 in the center line direction.
  • the seal member 7 shown in FIG. As shown in FIG. 2, the seal member 7 includes an end surface of the surrounding wall forming the communication hole 4 a in the cylinder head 4 in the tightening direction of the sensor unit 100, a third outer peripheral surface 333 of the housing 30 of the pressure detection device 5, It has the 1st seal member 71 arrange
  • the seal member 7 has a second seal member 72 disposed between the inclined portion 4c of the communication hole 4a of the cylinder head 4 and the inclined surface 315a of the first housing 31 of the housing 30 of the pressure detection device 5. is doing.
  • FIG. 9 is a diagram for explaining the configuration of the control device 6.
  • FIG. 9A is a block diagram for explaining the hardware configuration of the control device 6, and
  • FIG. 9B is a diagram for explaining a power feeding system in the control device 6.
  • the control apparatus 6 may be called ECU (Engine
  • the control device 6 as an example of the supply / processing unit includes signals output from various devices provided in a device (for example, an automobile) in which the internal combustion engine 1 is mounted, such as the pressure detection device 5 (in the case of the pressure detection device 5, an external device).
  • the MCU Micro Control Unit
  • the MCU Micro Control Unit
  • An EEPROM Electrically-Erasable-Programmable-Read-Only Memory
  • a power supply unit 66 for supplying power necessary for operating various devices (such as the pressure detecting device 5) provided outside the control
  • the input receiving unit 61 performs A / D conversion on an analog signal input from the outside to create a digital signal, or performs gain adjustment on the digital signal input from the outside, thereby allowing an input from the outside.
  • the input signal is converted into a state usable by the MCU 62.
  • the external output voltage Vo input from the pressure detection device 5 to the input receiving unit 61 is an analog signal.
  • the MCU 62 is configured by a so-called one-chip microcomputer, and temporarily executes MPU (Micro-Processing Unit) that performs various arithmetic processing, ROM (Read Only Memory) that stores a program executed by the MPU, and program execution by the MPU.
  • MPU Micro-Processing Unit
  • ROM Read Only Memory
  • Built-in RAM Random Access Memory
  • the EEPROM 63 is a non-volatile memory having a characteristic that stored data does not disappear even if power is not supplied.
  • the EEPROM 63 provided in the control device 6 stores, for example, data on the result of failure diagnosis executed when the device equipped with the internal combustion engine 1 is started, and troubles occurring in the operation of the internal combustion engine 1.
  • the drive signal output unit 64 performs D / A conversion on the digital signal as the calculation result input from the MCU 62 to create an analog signal, or adjusts the gain of the digital signal as the calculation result input from the MCU 62. By performing this, the output signal from the MCU 62 is converted into a state usable by various devices provided outside.
  • the communication unit 67 converts a communication signal received from another control device to a level that can be processed by the MCU 62. Moreover, the digital signal input from MCU62 is converted into the communication signal suitable for the communication standard between other control apparatuses.
  • the power supply unit 66 converts the battery voltage Vb (in this example, DC + 12V) input via an external power supply (for example, a battery in the case of an automobile) provided in a device on which the internal combustion engine 1 is mounted, to a lower operating voltage. It converts and supplies to MCU62 grade
  • the power supply unit 66 converts the input battery voltage Vb into a lower external power supply voltage Vc and outputs it to the pressure detection device 5 provided outside the control device 6.
  • the grounding end (GND) of the power supply unit 66 is connected to the outside (for example, the cylinder block 2 of the internal combustion engine 1 shown in FIG. 1).
  • the operating voltage output from the power supply unit 66 and the external power supply voltage Vc may have the same magnitude or different magnitudes.
  • FIG. 10 is a diagram for explaining an electrical connection relationship among the internal combustion engine 1, the pressure detection device 5, the control device 6, and the transmission cable 8.
  • one end of the piezoelectric element 10 is connected to the input signal terminal 211a of the mounting substrate 210 via the input-side first connection pin 21a and the like.
  • the other end of the piezoelectric element 10 is connected to the housing 30 (more specifically, the first housing 31) via a diaphragm head 40 (not shown in FIG. 10).
  • the input ground terminal 211b provided on the mounting substrate 210 is connected to the housing 30 (more specifically, the second housing 32) via the input-side second connection pin 21b and the like.
  • the power supply terminal 211c provided on the mounting board 210 is connected to the output side first connection pin 21c, and the output signal terminal 211d provided on the mounting board 210 is connected to the output side second connection pin 21d.
  • the output ground terminal 211e provided on the output side is connected to the output-side third connection pin 21e.
  • a cylinder block 2 and a cylinder head 4 both of which are made of metal, are arranged in contact with each other (see FIG. 1). Accordingly, the cylinder block 2 and the cylinder head 4 are connected to each other.
  • the output side first connection pin 21 c provided in the pressure detection device 5 is connected to one end of the first cable 81 constituting the transmission cable 8, and the other end of the first cable 81 is provided in the control device 6.
  • the power supply unit 66 (see FIG. 9) is connected to an output line (indicated by a solid arrow in the figure) of the external power supply voltage Vc.
  • the output-side second connection pin 21 d provided in the pressure detection device 5 is connected to one end of the second cable 82 that constitutes the transmission cable 8, and the other end of the second cable 82 is provided in the control device 6. Connected to the input receiving unit 61 (see FIG. 9).
  • the output-side third connection pin 21 e provided in the pressure detection device 5 is connected to one end of a third cable 83 constituting the transmission cable 8, and the other end of the third cable 83 is provided in the control device 6. Connected to a ground line (indicated by a broken-line arrow in the figure) of external power supply voltage Vc in power supply unit 66 (see FIG. 9).
  • the housing 30 provided in the pressure detection device 5 is attached to the cylinder head 4 provided in the internal combustion engine 1 by screwing as described above. Therefore, the housing 30 and the cylinder head 4 both made of metal are connected.
  • a grounding end of a power supply unit 66 (see FIG. 9) provided in the control device 6 is connected to a cylinder block 2 provided in the internal combustion engine 1.
  • the cylinder block 2 and the cylinder head 4 provided in the internal combustion engine 1 are connected as described above. Therefore, the ground of the piezoelectric element 10 in the pressure detection device 5, the ground of the mounting substrate 210 in the pressure detection device 5, and the ground of the power supply unit 66 (see FIG. 9) in the control device 6 are the cylinder block 2 and the cylinder head. 4 is set in common through the terminal 4. Further, in the present embodiment, the ground of the mounting substrate 210 in the pressure detection device 5 and the ground of the power supply unit 66 (see FIG. 9) in the control device 6 are shared via the third cable 83 of the transmission cable 8. Is set.
  • the pressure detection device 5 of the present embodiment may be sold alone or sold with the transmission cable 8 attached to the pressure detection device 5.
  • the output side first connection pin 21c functions as a constant voltage supply unit
  • the output side second connection pin 21d functions as an output signal transmission unit
  • the output side third connection pin 21e functions as a ground unit.
  • the first cable 81 connected to the output side first connection pin 21c is a constant voltage supply means
  • the second cable 82 connected to the output side second connection pin 21d is an output signal transmission means.
  • the third cables 83 connected to the output-side third connection pins 21e function as grounding means.
  • the transmission cable 8 (more specifically, the first cable 81, the second cable 82, and the like) that connects the pressure detection device 5 and the control device 6. Fault diagnosis (disconnection detection) of the third cable 83) is performed.
  • FIG. 11 is a flowchart for explaining the procedure of the disconnection detection operation at the start of the internal combustion engine 1.
  • an ignition switch (not shown) for starting the internal combustion engine 1 is set to ON (step 11)
  • the control device 6 sends an external output voltage from the power source 66 to the pressure detection device 5 via the transmission cable 8.
  • Vo power supply is started (step 12).
  • the control device 6 performs a disconnection detection operation of the transmission cable 8 connecting the control device 6 and the pressure detection device 5 (step 13), and determines whether or not a disconnection is detected (step 14).
  • step 14 If an affirmative determination (YES) is made in step 14, that is, if disconnection is detected in any of the first cable 81, the second cable 82, and the third cable 83 that constitute the transmission cable 8, the control device 6 Records data on which cable is detected to be disconnected in the EEPROM 63 built in the control device 6 (step 15). Subsequently, the control device 6 displays a message on the disconnection detection on a user interface (not shown) (step 16), and completes a series of processing.
  • step 14 if a negative determination (NO) is made in step 14, that is, if no disconnection is detected in any of the first cable 81, the second cable 82, and the third cable 83 constituting the transmission cable 8, The control device 6 completes the process as it is.
  • the output ground terminal 211e provided on the mounting substrate 210 of the pressure detection device 5 is connected to the power supply unit 66 of the control device 6 via the output-side third connection pin 21e and the third cable 83.
  • the power supply unit 66 is grounded via the cylinder block 2.
  • An input ground terminal 211b provided on the mounting board 210 of the pressure detection device 5 is connected to the housing 30 via the input-side second connection pin 21b.
  • the housing 30 is grounded via the cylinder head 4. Has been. For this reason, for example, even when a disconnection occurs in the third cable 83, there is a concern that the disconnection cannot be detected in the above-described disconnection detection operation because the mounting substrate 210 is grounded via the input ground terminal 211b. .
  • a DC cutoff circuit 215 is provided between the input ground terminal 211b and the output ground terminal 211e so that no DC current flows from the input ground terminal 211b toward the housing 30. I did it. Therefore, when direct current is supplied to the mounting board 210, the output ground terminal 211e has a function as ground, while the input ground terminal 211b does not have a function as ground. As a result, in the above-described disconnection detection operation, it is possible to detect the presence or absence of disconnection in the third cable 83 by supplying a DC signal as a signal for detecting disconnection.
  • the pressure detection operation by the pressure detection device 5 of the present embodiment will be described.
  • the combustion pressure generated in the combustion chamber C is applied to the inner portion 42 of the diaphragm head 40 of the sensor unit 100.
  • the combustion pressure applied to the diaphragm head 40 acts on the piezoelectric element 10 sandwiched between the first electrode portion 50 and the second electrode portion 55, so that electric charges corresponding to the combustion pressure are applied to the piezoelectric element 10.
  • Arise The electric charge generated in the piezoelectric element 10 is supplied to the mounting board 210 of the circuit board part 21 as the input electric charge Qi through the second electrode part 55, the coil spring 70 and the conductive member 22.
  • the input charge Qi supplied to the mounting board 210 is subjected to integration processing and amplification processing in various circuits provided on the mounting board 210, and then an external output voltage Vo corresponding to the charge is transmitted from the circuit board portion 21. It is supplied to the control device 6 via the cable 8.
  • the pressure detection device 5 of the present embodiment is attached to the internal combustion engine 1, and electromagnetic waves generated in accordance with the operation of the internal combustion engine 1 affect the mounting substrate 210 provided in the pressure detection device 5. give. That is, there is a concern that noise due to the above-described electromagnetic waves is superimposed on various signals used on the mounting substrate 210 and the external output voltage Vo output from the mounting substrate 210.
  • the input ground terminal 211b is provided on the mounting substrate 210 via the DC cutoff circuit 215. Therefore, AC component noise generated in each circuit passes through the DC cutoff circuit 215. Can be dropped to ground. For this reason, the noise superimposed on the external output voltage Vo transmitted from the pressure detection device 5 to the control device 6 can be reduced.
  • the disconnection detection of the transmission cable 8 that connects the pressure detection device 5 and the control device 6 using the piezoelectric element 10 has been described as an example.
  • the present invention is not limited to this.
  • the present invention can also be applied to detection of disconnection of the transmission cable 8 that connects the control device 6 and a detection device that detects various physical quantities such as temperature, humidity, or flow rate.
  • a capacitor is used as the DC cutoff circuit 215.
  • the present invention is not limited to this.
  • a diode having an anode on the input ground terminal 211b side may be used.
  • the DC cut-off circuit 215 is incorporated in the mounting board 210.
  • the present invention is not limited to this.
  • a DC cut-off circuit 215 is separately provided between the mounting board 210 and the housing 30. It doesn't matter.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Measuring Fluid Pressure (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

A mounting substrate (210) is provided with: an integration circuit (213), which integrates an input charge (Qi) obtained from a piezoelectric element (10) and converts the input charge into a piezoelectric signal; an amplifying circuit (214), which amplifies the piezoelectric signal; and a power supply circuit (216), which supplies an internal power supply voltage (Vr) to the integration circuit (213) and the amplifying circuit (214). The input charge (Qi) is inputted to the mounting substrate (210) from an input signal terminal (211a), an external power supply voltage (Vc) is inputted from a first cable via a power supply terminal (211c), and an external output voltage (Vo) is outputted from an output signal terminal (211d) via a second cable. Furthermore, the mounting substrate (210) is grounded from an output grounding terminal (211e) via a third cable, and is grounded from a direct-current blocking circuit (215) via the input grounding terminal (211b) and a housing.

Description

検出システムおよび検出装置Detection system and detection device
　本発明は、物理量を検出する検出システムおよび物理量を検出する検出装置に関する。 The present invention relates to a detection system that detects a physical quantity and a detection device that detects a physical quantity.
　例えば内燃機関を有する自動車等の装置では、装置内に圧力や温度等を検出する複数の検出装置が搭載されており、これらの検出装置による検出結果に基づき、ＥＣＵ（Engine　Control Unit）と呼ばれる制御装置が、内燃機関の動作等に関する制御を行っている。ここで、制御装置と検出装置とは、通常、制御装置から検出装置に給電を行うための電線、検出装置から制御装置に信号を送るための電線、および、制御装置と検出装置とのグランドを共通にするための電線、を用いて接続される。 For example, in an apparatus such as an automobile having an internal combustion engine, a plurality of detection devices that detect pressure, temperature, and the like are mounted in the device. Based on the detection results of these detection devices, a control called ECU (Engine Control Unit) is performed. The device controls the operation of the internal combustion engine. Here, the control device and the detection device are usually an electric wire for supplying power from the control device to the detection device, an electric wire for sending a signal from the detection device to the control device, and a ground between the control device and the detection device. It connects using the electric wire for making it common.
　例えば特許文献１には、ＥＣＵユニットと、電流路を流れる電流を検出する電流センサユニットとを備えた車載用のパワーステアリング装置システムにおいて、ＥＣＵユニットから電流センサユニットに電源を供給する電源ラインのグランド線の断線を、ＮチャンネルＦＥＴと抵抗とを有する回路を用いて検出する技術が記載されている。 For example, in Patent Document 1, in an in-vehicle power steering system including an ECU unit and a current sensor unit that detects a current flowing through a current path, a ground of a power supply line that supplies power from the ECU unit to the current sensor unit is disclosed. A technique for detecting a disconnection of a line using a circuit having an N-channel FET and a resistor is described.
特開２００８－５１７２２号公報JP 2008-51722 A
　ここで、上述した検出装置においては、検出信号にノイズが重畳されることがある。ここで、検出装置に設けられた信号処理回路におけるグランドが不安定な場合には、ノイズが重畳されやすくなってしまい、結果として、検出信号に基づいて得られる検出量に含まれる誤差が大きくなってしまうおそれがあった。
　本発明は、信号処理回路の接地に使用される電線の断線を検出可能にするとともに、信号処理回路からの出力信号におけるノイズの低減を図ることを目的とする。 Here, in the detection device described above, noise may be superimposed on the detection signal. Here, when the ground in the signal processing circuit provided in the detection device is unstable, noise is easily superimposed, and as a result, an error included in the detection amount obtained based on the detection signal increases. There was a risk of it.
An object of the present invention is to enable detection of disconnection of an electric wire used for grounding a signal processing circuit, and to reduce noise in an output signal from the signal processing circuit.
　本発明の検出システムは、物理量の変化を検出する検出素子と、当該検出素子から出力される検出信号に処理を施す信号処理回路と、当該検出素子および当該信号処理回路が取り付けられるとともに、接地体に電気的に接続される筐体と、当該筐体と当該信号処理回路におけるグランドとを、直流電流の通電を抑制しながら接続する直流抑制部とを含む検出部と、前記検出部における前記信号処理回路に定電圧を供給するための定電圧供給線と、当該信号処理部から出力される出力信号を伝送するための出力信号伝送線と、当該信号処理回路における前記グランドに接続するための接地線とを介して当該検出部に接続され、さらに、前記接地体に電気的に接続されることで、当該検出部に当該定電圧を供給するとともに当該検出部から入力される当該出力信号に処理を施す供給／処理部とを含んでいる。 The detection system of the present invention includes a detection element for detecting a change in physical quantity, a signal processing circuit for processing a detection signal output from the detection element, the detection element and the signal processing circuit, and a grounding body. A detector that includes a housing electrically connected to the housing, and a DC suppression unit that connects the housing and the ground in the signal processing circuit while suppressing energization of a DC current, and the signal in the detection unit A constant voltage supply line for supplying a constant voltage to the processing circuit, an output signal transmission line for transmitting an output signal output from the signal processing unit, and a ground for connecting to the ground in the signal processing circuit Is connected to the detection unit via a wire and is further electrically connected to the grounding body to supply the constant voltage to the detection unit and input from the detection unit. And a supply / processing units performs processing on the output signal.
　この検出システムにおいて、前記検出素子は、圧電体を用いて圧力を検出する圧電素子で構成され、前記信号処理回路は、前記圧電素子から入力される電荷信号を積分することで、当該電荷信号を電圧信号に変換する積分回路と、当該積分回路から入力される当該電圧信号を増幅し、得られた増幅信号を、前記出力信号伝送線を介して前記供給／処理部に出力する増幅回路とを有することが好ましい。これにより、微弱な電荷信号に基づいて増幅信号を得る場合においても、増幅信号に含まれるノイズを低減することができる。 In this detection system, the detection element is composed of a piezoelectric element that detects pressure using a piezoelectric body, and the signal processing circuit integrates the charge signal input from the piezoelectric element, thereby obtaining the charge signal. An integrating circuit for converting the voltage signal; and an amplifying circuit for amplifying the voltage signal input from the integrating circuit and outputting the obtained amplified signal to the supply / processing unit via the output signal transmission line. It is preferable to have. Thereby, even when an amplified signal is obtained based on a weak charge signal, noise contained in the amplified signal can be reduced.
　また、前記信号処理回路は、前記定電圧供給線を介して入力される前記定電圧を、当該定電圧よりも低い電圧に変換して、前記積分回路および前記増幅回路に供給する電源回路をさらに備えることが好ましい。これにより、積分回路および増幅回路を、例えば演算増幅器を含む構成とすることができる。
　さらに、前記直流抑制部は、コンデンサを含むことが好ましい。これにより、簡易な構成で直流遮断回路を構成することができる。 The signal processing circuit further includes a power supply circuit that converts the constant voltage input via the constant voltage supply line into a voltage lower than the constant voltage and supplies the voltage to the integrating circuit and the amplifier circuit. It is preferable to provide. Thereby, the integration circuit and the amplification circuit can be configured to include, for example, an operational amplifier.
Furthermore, it is preferable that the direct current suppression unit includes a capacitor. As a result, the DC cutoff circuit can be configured with a simple configuration.
　また、他の観点から捉えると、本発明の検出装置は、物理量の変化を検出する検出素子と、前記検出素子から出力される検出信号に処理を施す信号処理回路と、前記検出素子および前記信号処理回路が取り付けられる筐体と、前記信号処理回路に定電圧を供給するための定電圧供給手段と、前記信号処理回路から出力される出力信号を伝送するための出力信号伝送手段と、前記信号処理回路におけるグランドに接続するための接地手段と、前記筐体と前記信号処理回路における前記グランドとを、直流電流の通電を抑制しながら接続する直流抑制部とを含んでいる。 From another viewpoint, the detection apparatus of the present invention includes a detection element that detects a change in physical quantity, a signal processing circuit that processes a detection signal output from the detection element, the detection element, and the signal A housing to which a processing circuit is attached, a constant voltage supply means for supplying a constant voltage to the signal processing circuit, an output signal transmission means for transmitting an output signal output from the signal processing circuit, and the signal A grounding means for connecting to the ground in the processing circuit; and a direct current suppression unit that connects the casing and the ground in the signal processing circuit while suppressing the application of direct current.
　本発明によれば、信号処理回路の接地に使用される電線の断線を検出可能にするとともに、信号処理回路からの出力信号におけるノイズの低減を図ることができる。 According to the present invention, it is possible to detect disconnection of an electric wire used for grounding a signal processing circuit and to reduce noise in an output signal from the signal processing circuit.
実施の形態に係る内燃機関の概略構成図である。1 is a schematic configuration diagram of an internal combustion engine according to an embodiment. 図１に示す圧力検出装置のＩＩ部の拡大図である。It is an enlarged view of the II section of the pressure detection apparatus shown in FIG. 圧力検出装置の概略構成図である。It is a schematic block diagram of a pressure detection apparatus. 図３に示す圧力検出装置のＩＶ－ＩＶ部の断面図である。FIG. 4 is a cross-sectional view of the IV-IV part of the pressure detection device shown in FIG. 3. 図４に示す圧力検出装置のＶ部の拡大図である。It is an enlarged view of the V section of the pressure detection apparatus shown in FIG. 図４に示す圧力検出装置のＶＩ部の拡大図である。It is an enlarged view of VI part of the pressure detection apparatus shown in FIG. 実装基板における回路構成図である。It is a circuit block diagram in a mounting substrate. 実装基板に設けられた電源回路の回路構成図である。It is a circuit block diagram of the power supply circuit provided in the mounting board | substrate. 制御装置の構成を説明するための図である。It is a figure for demonstrating the structure of a control apparatus. 内燃機関、圧力検出装置、制御装置および伝送ケーブルの、電気的な接続関係を説明するための図である。It is a figure for demonstrating the electrical connection relationship of an internal combustion engine, a pressure detection apparatus, a control apparatus, and a transmission cable. 内燃機関の始動時における断線検出動作の手順を説明するためのフローチャートである。It is a flowchart for demonstrating the procedure of the disconnection detection operation | movement at the time of start-up of an internal combustion engine.
　以下、添付図面を参照して、本発明の実施の形態について詳細に説明する。
　図１は、本実施形態に係る内燃機関１の概略構成図である。また、図２は、図１に示す圧力検出装置５のＩＩ部の拡大図である。
　内燃機関１は、シリンダ２ａを有するシリンダブロック２と、シリンダ２ａ内を往復動するピストン３と、シリンダブロック２に締結されてシリンダ２ａおよびピストン３などとともに燃焼室Ｃを形成するシリンダヘッド４と、を備えている。ここで、シリンダブロック２およびシリンダヘッド４は、ともに、導電性を有するアルミニウムあるいは鋳鉄等で構成されている。また、内燃機関１は、シリンダヘッド４に装着されて燃焼室Ｃ内の圧力を検出する圧力検出装置５と、圧力検出装置５が検出した圧力に基づいて内燃機関１の作動を制御する制御装置６と、圧力検出装置５とシリンダヘッド４との間に介在して燃焼室Ｃ内の気密性を保つためのシール部材７と、圧力検出装置５と制御装置６との間で電気信号を伝送する伝送ケーブル８と、を備えている。 Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of an internal combustion engine 1 according to the present embodiment. 2 is an enlarged view of the II part of the pressure detection device 5 shown in FIG.
The internal combustion engine 1 includes a cylinder block 2 having a cylinder 2a, a piston 3 that reciprocates in the cylinder 2a, a cylinder head 4 that is fastened to the cylinder block 2 and forms a combustion chamber C together with the cylinder 2a, the piston 3, and the like, It has. Here, both the cylinder block 2 and the cylinder head 4 are made of conductive aluminum, cast iron, or the like. The internal combustion engine 1 is mounted on the cylinder head 4 to detect the pressure in the combustion chamber C, and a control device that controls the operation of the internal combustion engine 1 based on the pressure detected by the pressure detection device 5. 6, an electric signal is transmitted between the pressure detection device 5 and the control device 6, and between the pressure detection device 5 and the control device 6, which is interposed between the pressure detection device 5 and the cylinder head 4 and maintains the airtightness in the combustion chamber C. A transmission cable 8.
　そして、伝送ケーブル８は、図２に示すように、３本のケーブルすなわち第１ケーブル８１、第２ケーブル８２および第３ケーブル８３と、これら第１ケーブル８１～第３ケーブル８３を圧力検出装置５に接続するためのコネクタ８０とを有している。ここで、第１ケーブル８１、第２ケーブル８２および第３ケーブル８３は、それぞれ、錫メッキ軟銅撚り線からなる導体部の外周面に、樹脂製の絶縁体を被覆してなる絶縁電線にて構成されている。なお、本実施の形態では、第１ケーブル８１が定電圧供給線として、第２ケーブル８２が出力信号伝送線として、第３ケーブル８３が接地線として、それぞれ機能している。 As shown in FIG. 2, the transmission cable 8 includes three cables, that is, a first cable 81, a second cable 82, and a third cable 83, and the first cable 81 to the third cable 83. And a connector 80 for connecting to the connector. Here, each of the first cable 81, the second cable 82, and the third cable 83 is constituted by an insulated wire in which the outer peripheral surface of a conductor portion made of a tinned annealed copper stranded wire is coated with a resin insulator. Has been. In the present embodiment, the first cable 81 functions as a constant voltage supply line, the second cable 82 functions as an output signal transmission line, and the third cable 83 functions as a ground line.
　また、図２に示すように、シリンダヘッド４には、燃焼室Ｃと外部とを連通する連通孔４ａが形成されている。連通孔４ａは、燃焼室Ｃ側から、第１孔部４ｂと、第１孔部４ｂの孔径から徐々に径が拡大している傾斜部４ｃと、第１孔部４ｂの孔径よりも孔径が大きい第２孔部４ｄと、を有している。第２孔部４ｄを形成する周囲の壁には、圧力検出装置５に形成された後述するハウジング３０の雄ねじ３３２ａがねじ込まれる雌ねじ４ｅが形成されている。 Further, as shown in FIG. 2, the cylinder head 4 is formed with a communication hole 4a for communicating the combustion chamber C with the outside. From the combustion chamber C side, the communication hole 4a has a hole diameter larger than the first hole part 4b, the inclined part 4c whose diameter gradually increases from the hole diameter of the first hole part 4b, and the hole diameter of the first hole part 4b. A large second hole 4d. A female screw 4e into which a male screw 332a of the housing 30 (described later) formed in the pressure detection device 5 is screwed is formed on the surrounding wall forming the second hole 4d.
　以下に、圧力検出装置５について詳述する。
　図３は、検出部あるいは検出装置の一例としての圧力検出装置５の概略構成図である。図４は、図３に示す圧力検出装置５のＩＶ－ＩＶ部の断面図である。図５は、図４に示す圧力検出装置５のＶ部の拡大図である。また、図６は、図４に示す圧力検出装置５のＶＩ部の拡大図である。 Below, the pressure detection apparatus 5 is explained in full detail.
FIG. 3 is a schematic configuration diagram of a pressure detection device 5 as an example of a detection unit or a detection device. 4 is a cross-sectional view of the IV-IV portion of the pressure detection device 5 shown in FIG. FIG. 5 is an enlarged view of a V portion of the pressure detection device 5 shown in FIG. FIG. 6 is an enlarged view of a VI part of the pressure detection device 5 shown in FIG.
　圧力検出装置５は、燃焼室Ｃ内の圧力を電気信号に変換する圧電素子１０を有するセンサ部１００と、センサ部１００からの電気信号を処理する信号処理部２００と、信号処理部２００を保持する保持部材３００と、を備えている。この圧力検出装置５をシリンダヘッド４に装着する際には、センサ部１００の後述するダイアフラムヘッド４０の方から先に、シリンダヘッド４に形成された連通孔４ａに挿入していく。以下の説明において、図４の左側を圧力検出装置５の先端側、右側を圧力検出装置５の後端側とする。 The pressure detection device 5 includes a sensor unit 100 having a piezoelectric element 10 that converts the pressure in the combustion chamber C into an electric signal, a signal processing unit 200 that processes an electric signal from the sensor unit 100, and a signal processing unit 200. Holding member 300. When the pressure detection device 5 is mounted on the cylinder head 4, the diaphragm head 40 (described later) of the sensor unit 100 is inserted into the communication hole 4 a formed in the cylinder head 4 first. In the following description, the left side of FIG. 4 is the front end side of the pressure detection device 5, and the right side is the rear end side of the pressure detection device 5.
　先ずは、センサ部１００について説明する。
　センサ部１００は、受けた圧力を電気信号に変換する圧電素子１０と、筒状であってその内部に圧電素子１０などを収納する円柱状の孔が形成されたハウジング３０と、を備えている。以下では、ハウジング３０に形成された円柱状の孔の中心線方向を、単に中心線方向と称す。 First, the sensor unit 100 will be described.
The sensor unit 100 includes a piezoelectric element 10 that converts received pressure into an electrical signal, and a housing 30 that is cylindrical and in which a cylindrical hole that accommodates the piezoelectric element 10 and the like is formed. . Hereinafter, the center line direction of the cylindrical hole formed in the housing 30 is simply referred to as a center line direction.
　また、センサ部１００は、ハウジング３０における先端側の開口部を塞ぐように設けられて、燃焼室Ｃ内の圧力が作用するダイアフラムヘッド４０と、ダイアフラムヘッド４０と圧電素子１０との間に設けられた第１電極部５０と、圧電素子１０に対して第１電極部５０とは反対側に配置された第２電極部５５と、を備えている。
　また、センサ部１００は、第２電極部５５を電気的に絶縁するアルミナセラミック製の絶縁リング６０と、絶縁リング６０よりも後端側に設けられて、信号処理部２００の後述する覆い部材２３の端部を支持する支持部材６５と、第２電極部５５と後述する伝導部材２２との間に介在するコイルスプリング７０と、を備えている。 The sensor unit 100 is provided so as to close the opening on the distal end side of the housing 30, and is provided between the diaphragm head 40 on which the pressure in the combustion chamber C acts, and between the diaphragm head 40 and the piezoelectric element 10. The first electrode unit 50 and the second electrode unit 55 disposed on the opposite side of the piezoelectric element 10 from the first electrode unit 50 are provided.
The sensor unit 100 is provided with an insulating ring 60 made of alumina ceramic that electrically insulates the second electrode unit 55 and a rear end side of the insulating ring 60, and a covering member 23 described later of the signal processing unit 200. And a coil spring 70 interposed between the second electrode portion 55 and a conductive member 22 described later.
　圧電素子１０は、圧電縦効果の圧電作用を示す圧電体を有している。圧電縦効果とは、圧電体の電荷発生軸と同一方向の応力印加軸に外力を作用させると、電荷発生軸方向の圧電体の表面に電荷が発生する作用をいう。本実施形態に係る圧電素子１０は、中心線方向が応力印加軸の方向となるようにハウジング３０内に収納されている。 The piezoelectric element 10 has a piezoelectric body that exhibits the piezoelectric action of the piezoelectric longitudinal effect. The piezoelectric longitudinal effect refers to the action of generating charges on the surface of the piezoelectric body in the direction of the charge generation axis when an external force is applied to the stress application axis in the same direction as the charge generation axis of the piezoelectric body. The piezoelectric element 10 according to the present embodiment is housed in the housing 30 so that the center line direction is the direction of the stress application axis.
　次に、圧電素子１０に圧電横効果を利用した場合を例示する。圧電横効果とは、圧電体の電荷発生軸に対して直交する位置にある応力印加軸に外力を作用させると、電荷発生軸方向の圧電体の表面に電荷が発生する作用をいう。薄板状に薄く形成した圧電体を複数枚積層して構成しても良く、このように積層することで、圧電体に発生する電荷を効率的に集めてセンサの感度を上げることができる。圧電体としては、圧電縦効果及び圧電横効果を有するランガサイト系結晶（ランガサイト、ランガテイト、ランガナイト、ＬＧＴＡ）や水晶、ガリウムリン酸塩などを使用することを例示することができる。なお、本実施形態の圧電素子１０には、圧電体としてランガサイト単結晶を用いている。 Next, the case where the piezoelectric lateral effect is used for the piezoelectric element 10 will be exemplified. The piezoelectric transverse effect is an action in which charges are generated on the surface of the piezoelectric body in the direction of the charge generation axis when an external force is applied to the stress application axis at a position orthogonal to the charge generation axis of the piezoelectric body. A plurality of thinly formed piezoelectric bodies may be laminated, and by laminating in this way, the charge generated in the piezoelectric bodies can be efficiently collected to increase the sensitivity of the sensor. Examples of the piezoelectric body include the use of a langasite crystal (a langasite, langagate, langanite, LGTA) having a piezoelectric longitudinal effect and a piezoelectric transverse effect, quartz, gallium phosphate, and the like. In the piezoelectric element 10 of the present embodiment, a langasite single crystal is used as the piezoelectric body.
　筐体の一例としてのハウジング３０は、図５に示すように、先端側に設けられた第１ハウジング３１と、後端側に設けられた第２ハウジング３２と、を有する。
　第１ハウジング３１は、内部に、先端側から後端側にかけて段階的に径が異なるように形成された円柱状の孔３１０が形成された薄肉円筒状の部材である。外周面には、中心線方向の中央部に、外周面から突出する突出部３１５が周方向の全域に渡って設けられている。
　孔３１０は、先端側から後端側にかけて順に形成された、第１孔３１１と、第１孔３１１の孔径よりも大きな孔径の第２孔３１２と、から構成される。突出部３１５は、先端部に、先端側から後端側にかけて徐々に径が大きくなる傾斜面３１５ａを有し、後端部に、中心線方向に垂直な垂直面３１５ｂを有している。 As shown in FIG. 5, the housing 30 as an example of the housing includes a first housing 31 provided on the front end side and a second housing 32 provided on the rear end side.
The first housing 31 is a thin-walled cylindrical member having a cylindrical hole 310 formed therein so as to have a diameter that gradually changes from the front end side to the rear end side. On the outer peripheral surface, a projecting portion 315 that protrudes from the outer peripheral surface is provided in the central portion in the center line direction over the entire region in the circumferential direction.
The hole 310 includes a first hole 311 and a second hole 312 having a diameter larger than the diameter of the first hole 311 formed in order from the front end side to the rear end side. The protrusion 315 has an inclined surface 315a whose diameter gradually increases from the front end side to the rear end side at the front end portion, and a vertical surface 315b perpendicular to the center line direction at the rear end portion.
　第２ハウジング３２は、図４に示すように、内部に、先端側から後端側にかけて段階的に径が異なるように形成された円柱状の孔３２０が形成された筒状の部材であり、外部に、先端側から後端側にかけて段階的に径が異なるように形成された外周面３３０が設けられている。
　孔３２０は、先端側から後端側にかけて順に形成された、第１孔径を有する第１円柱孔３２１と、第１孔径よりも小さな第２孔径を有する第２円柱孔３２２と、第２孔径よりも大きな第３孔径を有する第３円柱孔３２３と、第３孔径よりも大きな第４孔径を有する第４円柱孔３２４と、第４孔径よりも大きな第５孔径を有する第５円柱孔３２５と、から構成される。
　第２ハウジング３２における先端部は、第１ハウジング３１における後端部にしまりばめで嵌合（圧入）されるように、第１円柱孔３２１における第１孔径は、第１ハウジング３１の外周面の径以下となるように設定されている。 As shown in FIG. 4, the second housing 32 is a cylindrical member in which a cylindrical hole 320 is formed so that the diameter gradually changes from the front end side to the rear end side. An outer peripheral surface 330 is formed on the outside so that the diameter is gradually changed from the front end side to the rear end side.
The hole 320 includes a first cylindrical hole 321 having a first hole diameter, a second cylindrical hole 322 having a second hole diameter smaller than the first hole diameter, and a second hole diameter. A third cylindrical hole 323 having a larger third hole diameter, a fourth cylindrical hole 324 having a fourth hole diameter larger than the third hole diameter, a fifth cylindrical hole 325 having a fifth hole diameter larger than the fourth hole diameter, Consists of
The first hole diameter in the first cylindrical hole 321 is such that the front end of the second housing 32 is fitted (press-fit) to the rear end of the first housing 31 with an interference fit. It is set to be less than the diameter.
　外周面３３０は、先端側から後端側にかけて、第１外周面３３１と、第１外周面３３１の外径よりも大きな外径の第２外周面３３２と、第２外周面３３２の外径よりも大きな外径の第３外周面３３３と、第３外周面３３３の外径よりも大きな外径の第４外周面３３４と、第４外周面３３４の外径よりも小さな外径の第５外周面３３５と、から構成される。
　第２外周面３３２における先端部には、シリンダヘッド４の雌ねじ４ｅにねじ込まれる雄ねじ３３２ａが形成されている。第３外周面３３３には、後述する第１シール部材７１がすきまばめで嵌め込まれ、第３外周面３３３の外径と第１シール部材７１の内径との寸法公差は、例えば零から０．２ｍｍとなるように設定される。第４外周面３３４における後端部は、周方向に等間隔に６つの面取りを有する正六角柱に形成されている。この正六角柱に形成された部位が、圧力検出装置５をシリンダヘッド４に締め付ける際に、締付用の工具が嵌め込まれ、工具に付与された回転力が伝達される部位となる。第５外周面３３５における中心線方向の中央部には、外周面から凹んだ凹部３３５ａが全周に渡って形成されている。 The outer peripheral surface 330 has a first outer peripheral surface 331, a second outer peripheral surface 332 having an outer diameter larger than the outer diameter of the first outer peripheral surface 331, and an outer diameter of the second outer peripheral surface 332 from the front end side to the rear end side. A third outer peripheral surface 333 having a larger outer diameter, a fourth outer peripheral surface 334 having an outer diameter larger than the outer diameter of the third outer peripheral surface 333, and a fifth outer periphery having an outer diameter smaller than the outer diameter of the fourth outer peripheral surface 334 A surface 335.
A male screw 332 a that is screwed into the female screw 4 e of the cylinder head 4 is formed at the tip of the second outer peripheral surface 332. A first seal member 71, which will be described later, is fitted into the third outer peripheral surface 333 with a clearance fit, and the dimensional tolerance between the outer diameter of the third outer peripheral surface 333 and the inner diameter of the first seal member 71 is, for example, from zero to 0.2 mm. Is set to be The rear end portion of the fourth outer peripheral surface 334 is formed as a regular hexagonal column having six chamfers at equal intervals in the circumferential direction. When the pressure detecting device 5 is fastened to the cylinder head 4, the portion formed in the regular hexagonal column is a portion into which a tightening tool is fitted and a rotational force applied to the tool is transmitted. A concave portion 335a that is recessed from the outer peripheral surface is formed over the entire circumference in the center portion of the fifth outer peripheral surface 335 in the center line direction.
　また、図６に示すように、第２ハウジング３２は、第４円柱孔３２４から第５円柱孔３２５への移行部分であり、第５円柱孔３２５（図４参照）における先端部には、信号処理部２００の後述する覆い部材２３の基板被覆部２３２における先端側の端面が突き当たる突当面３４０が設けられている。突当面３４０には、後述する信号処理部２００における回路基板部２１の入力側第２接続ピン２１ｂが差し込まれるピン用凹部３４０ａが形成されている。 Further, as shown in FIG. 6, the second housing 32 is a transition portion from the fourth cylindrical hole 324 to the fifth cylindrical hole 325, and a signal is placed at the tip of the fifth cylindrical hole 325 (see FIG. 4). An abutting surface 340 against which an end surface on the front end side of the substrate covering portion 232 of the covering member 23 described later of the processing unit 200 abuts is provided. The abutting surface 340 is formed with a pin recess 340a into which the input-side second connection pin 21b of the circuit board unit 21 in the signal processing unit 200 described later is inserted.
　第１ハウジング３１および第２ハウジング３２は、燃焼室Ｃに近い位置に存在するため、少なくとも、－４０～３５０〔℃〕の使用温度環境に耐える材料を用いて製作することが望ましい。また、第１ハウジング３１および第２ハウジング３２は、後述するように、ハウジング３０内に収容される各部の接地に使用されることから、導電性を有する材料を用いて製作することが望ましい。具体的には、導電性を有し且つ耐熱性の高いステンレス鋼材、例えば、ＪＩＳ規格のＳＵＳ６３０、ＳＵＳ３１６、ＳＵＳ４３０等を用いることが望ましい。 Since the first housing 31 and the second housing 32 exist at a position close to the combustion chamber C, it is desirable to manufacture the first housing 31 and the second housing 32 using a material that can withstand at least an operating temperature environment of −40 to 350 [° C.]. Moreover, since the 1st housing 31 and the 2nd housing 32 are used for the earthing | grounding of each part accommodated in the housing 30 so that it may mention later, it is desirable to manufacture using the material which has electroconductivity. Specifically, it is desirable to use a stainless steel material having conductivity and high heat resistance, for example, JIS standard SUS630, SUS316, SUS430, or the like.
　ダイアフラムヘッド４０は、図５に示すように、円筒状の円筒状部４１と、円筒状部４１の内側に形成された内側部４２と、を有している。
　円筒状部４１における後端部は、ハウジング３０の第１ハウジング３１における先端部としまりばめで嵌合（圧入）されて、この先端部の内部に入り込む進入部４１ａと、この先端部における端面３１ａと同形状に形成され、嵌合された際にこの端面３１ａが突き当たる突当面４１ｂと、を有している。
　内側部４２は、円筒状部４１における先端側の開口を塞ぐように設けられた円盤状の部材であり、後端側の面における中央部にはこの面から圧電素子１０側に突出する突出部４２ａが設けられている。また、内側部４２の、先端側の面における中央部にはこの面から圧電素子１０側に凹んだ凹部４２ｂが設けられている。
　ダイアフラムヘッド４０の材料としては、高温でありかつ高圧となる燃焼室Ｃ内に存在するため、弾性が高く、かつ耐久性、耐熱性、耐触性等に優れた合金製であることが望ましく、例えばＳＵＨ６６０を例示することができる。 As shown in FIG. 5, the diaphragm head 40 has a cylindrical cylindrical portion 41 and an inner portion 42 formed inside the cylindrical portion 41.
The rear end portion of the cylindrical portion 41 is fitted (press-fitted) with the front end portion of the first housing 31 of the housing 30 with an interference fit, and enters the inside of the front end portion, and the end surface 31a at the front end portion. And an abutting surface 41b against which the end surface 31a abuts when fitted.
The inner part 42 is a disk-shaped member provided so as to close the opening on the front end side in the cylindrical part 41, and a protruding part that protrudes from this surface to the piezoelectric element 10 side in the central part on the rear end side surface 42a is provided. Further, a concave portion 42b that is recessed from this surface to the piezoelectric element 10 side is provided at the center of the inner portion 42 on the front end side surface.
The material of the diaphragm head 40 is preferably made of an alloy having high elasticity and excellent durability, heat resistance, touch resistance, and the like because it exists in the combustion chamber C at a high temperature and a high pressure. For example, SUH660 can be illustrated.
　第１電極部５０は、先端側から後端側にかけて段階的に径が異なるように形成された円柱状の部材であり、第１円柱部５１と、第１円柱部５１の半径よりも大きな半径の第２円柱部５２と、から構成される。第１円柱部５１の外径はダイアフラムヘッド４０の進入部４１ａの内径よりも小さく、第２円柱部５２の外径は第１ハウジング３１の第１孔３１１の孔径と略同じである。そして、第１円柱部５１における先端側の端面がダイアフラムヘッド４０の内側部４２の突出部４２ａと、第２円柱部５２における後端側の端面が圧電素子１０における先端側の面とに接触するように配置される。第２円柱部５２の外周面が第１ハウジング３１の内周面と接触すること、および／または第１円柱部５１における先端側の端面がダイアフラムヘッド４０と接触することによって、圧電素子１０における先端部は、ハウジング３０と電気的に接続される。
　第１電極部５０は、燃焼室Ｃ内の圧力を圧電素子１０に作用させるものであり、圧電素子１０側の端面である第２円柱部５２における後端側の端面が圧電素子１０の端面の全面を押すことが可能な大きさに形成される。また、第１電極部５０は、ダイアフラムヘッド４０から受ける圧力を均等に圧電素子１０に作用させることができるように、中心線方向の両端面が、それぞれ平滑面に形成されるとともに、中心線方向と直交する面に沿って互いに略平行に設けられている。
　第１電極部５０の材質としては、ステンレスを例示することができる。 The first electrode portion 50 is a columnar member formed so as to have a stepwise difference in diameter from the front end side to the rear end side, and has a radius larger than the radius of the first columnar portion 51 and the first columnar portion 51. The second cylindrical portion 52. The outer diameter of the first cylindrical portion 51 is smaller than the inner diameter of the entry portion 41 a of the diaphragm head 40, and the outer diameter of the second cylindrical portion 52 is substantially the same as the hole diameter of the first hole 311 of the first housing 31. The end surface on the front end side of the first cylindrical portion 51 is in contact with the protruding portion 42 a of the inner side portion 42 of the diaphragm head 40, and the end surface on the rear end side of the second cylindrical portion 52 is in contact with the front surface side of the piezoelectric element 10. Are arranged as follows. When the outer peripheral surface of the second cylindrical portion 52 is in contact with the inner peripheral surface of the first housing 31 and / or the end surface on the distal end side of the first cylindrical portion 51 is in contact with the diaphragm head 40, the distal end of the piezoelectric element 10 is obtained. The part is electrically connected to the housing 30.
The first electrode portion 50 applies pressure in the combustion chamber C to the piezoelectric element 10, and the end surface on the rear end side of the second cylindrical portion 52, which is the end surface on the piezoelectric element 10 side, is the end surface of the piezoelectric element 10. It is formed in a size that can push the entire surface. In addition, the first electrode portion 50 has both end surfaces in the center line direction formed as smooth surfaces so that the pressure received from the diaphragm head 40 can be applied to the piezoelectric element 10 evenly, and the first electrode portion 50 has a center line direction. Are provided substantially in parallel with each other along a plane orthogonal to each other.
An example of the material of the first electrode unit 50 is stainless steel.
　第２電極部５５は、円柱状の部材であり、先端側の端面が圧電素子１０における後端側の端面に接触し、後端側の端面が絶縁リング６０に接触するように配置される。第２電極部５５における後端側の端面には、この端面から後端側に突出する円柱状の突出部５５ａが設けられている。突出部５５ａは、端面側の基端部と、この基端部の外径よりも小さな外径の先端部と、を有する。突出部５５ａの外径は絶縁リング６０の内径よりも小さく設定されるとともに、突出部５５ａの長さは絶縁リング６０の幅（中心線方向の長さ）よりも長く設定され、突出部５５ａの先端が絶縁リング６０から露出している。この第２電極部５５は、第１電極部５０との間で圧電素子１０に対して一定の荷重を加えるように作用する部材であり、圧電素子１０側（先端側）の端面は、圧電素子１０の後端側の端面の全面を押すことが可能な大きさに形成されるとともに、平滑面且つ圧電素子１０の後端側の端面と平行な面に形成されている。第２電極部５５の外径は第１ハウジング３１の第２孔３１２の孔径よりも小さくなるように設定されており、第２電極部５５の外周面と第１ハウジング３１の内周面との間には隙間がある。
　第２電極部５５の材質としては、ステンレスを例示することができる。 The second electrode portion 55 is a columnar member, and is disposed such that the end surface on the front end side is in contact with the end surface on the rear end side in the piezoelectric element 10 and the end surface on the rear end side is in contact with the insulating ring 60. A columnar projecting portion 55 a that projects from the end surface to the rear end side is provided on the end surface on the rear end side of the second electrode portion 55. The protrusion 55a has a base end portion on the end face side and a tip end portion having an outer diameter smaller than the outer diameter of the base end portion. The outer diameter of the protruding portion 55a is set smaller than the inner diameter of the insulating ring 60, and the length of the protruding portion 55a is set longer than the width of the insulating ring 60 (the length in the center line direction). The tip is exposed from the insulating ring 60. The second electrode portion 55 is a member that acts to apply a constant load to the piezoelectric element 10 between the second electrode portion 50 and the end face on the piezoelectric element 10 side (tip side) is a piezoelectric element. 10 is formed to have a size capable of pressing the entire end face on the rear end side of the surface 10 and a flat surface parallel to the end face on the rear end side of the piezoelectric element 10. The outer diameter of the second electrode portion 55 is set to be smaller than the hole diameter of the second hole 312 of the first housing 31, and the outer peripheral surface of the second electrode portion 55 and the inner peripheral surface of the first housing 31 are set. There is a gap between them.
An example of the material of the second electrode portion 55 is stainless steel.
　絶縁リング６０は、アルミナセラミックス等により形成された円筒状の部材であり、内径（中央部の孔径）は、第２電極部５５の突出部５５ａの基端部の外径よりもやや大きく、外径は、第１ハウジング３１の第２孔３１２の孔径と略同じに設定されている。第２電極部５５は、突出部５５ａが絶縁リング６０の中央部の孔に挿入されて配置されることで、第２電極部５５の中心位置と第１ハウジング３１の第２孔３１２の中心とが同じになるように配置される。 The insulating ring 60 is a cylindrical member formed of alumina ceramic or the like, and the inner diameter (hole diameter at the center) is slightly larger than the outer diameter of the base end portion of the protruding portion 55a of the second electrode portion 55. The diameter is set to be substantially the same as the hole diameter of the second hole 312 of the first housing 31. The second electrode portion 55 is disposed with the protruding portion 55a inserted into the central hole of the insulating ring 60, so that the center position of the second electrode portion 55 and the center of the second hole 312 of the first housing 31 are Are arranged to be the same.
　支持部材６５は、先端側から後端側にかけて、内部に、径が異なる複数の円柱状の孔６５０が形成され、外周面の径が同一の、筒状の部材である。
　孔６５０は、先端側から後端側にかけて順に形成された、第１孔６５１と、第１孔６５１の孔径よりも大きな孔径の第２孔６５２と、第２孔６５２の孔径よりも大きな孔径の第３孔６５３と、から構成される。第１孔６５１の孔径は、第２電極部５５の突出部５５ａの基端部の外径よりも大きく、この突出部５５ａが支持部材６５の内部まで露出する。第２孔６５２の孔径は、後述する信号処理部２００の伝導部材２２における先端部の外径よりも大きい。第３孔６５３の孔径は、後述する信号処理部２００の覆い部材２３における先端側の端部の外径よりも小さく、この覆い部材２３が第３孔６５３を形成する周囲の壁にしまりばめで嵌合される。これにより、支持部材６５は、覆い部材２３の端部を支持する部材として機能する。 The support member 65 is a cylindrical member in which a plurality of cylindrical holes 650 having different diameters are formed inside from the front end side to the rear end side, and the diameter of the outer peripheral surface is the same.
The holes 650 are formed in order from the front end side to the rear end side, and have a first hole 651, a second hole 652 having a diameter larger than the diameter of the first hole 651, and a diameter larger than the diameter of the second hole 652. A third hole 653. The diameter of the first hole 651 is larger than the outer diameter of the base end portion of the protruding portion 55 a of the second electrode portion 55, and the protruding portion 55 a is exposed to the inside of the support member 65. The hole diameter of the second hole 652 is larger than the outer diameter of the distal end portion of the conductive member 22 of the signal processing unit 200 described later. The hole diameter of the third hole 653 is smaller than the outer diameter of the end portion on the front end side of the covering member 23 of the signal processing unit 200 described later, and the covering member 23 is fitted to the surrounding wall forming the third hole 653. Mated. Thereby, the support member 65 functions as a member that supports the end portion of the covering member 23.
　コイルスプリング７０は、内径が、第２電極部５５の突出部５５ａにおける先端部の外径以上で基端部の外径より小さく、外径が、後述する伝導部材２２の挿入孔２２ａの径よりも小さい。コイルスプリング７０の内側に第２電極部５５の突出部５５ａの先端部が挿入されるとともに、コイルスプリング７０は、後述する伝導部材２２の挿入孔２２ａに挿入される。コイルスプリング７０の長さは、第２電極部５５と伝導部材２２との間に圧縮した状態で介在することができる長さに設定されている。コイルスプリング７０の材質としては、弾性が高く、かつ耐久性、耐熱性、耐触性等に優れた合金を用いるとよい。また、コイルスプリング７０の表面に金メッキを施すことで、電気伝導を高めるとよい。 The coil spring 70 has an inner diameter that is equal to or larger than the outer diameter of the distal end portion of the protruding portion 55a of the second electrode portion 55 and smaller than the outer diameter of the proximal end portion, and the outer diameter is smaller than the diameter of the insertion hole 22a of the conductive member 22 described later. Is also small. The distal end portion of the protruding portion 55a of the second electrode portion 55 is inserted inside the coil spring 70, and the coil spring 70 is inserted into an insertion hole 22a of the conductive member 22 described later. The length of the coil spring 70 is set to a length that can be interposed in a compressed state between the second electrode portion 55 and the conductive member 22. As a material of the coil spring 70, an alloy having high elasticity and excellent durability, heat resistance, touch resistance and the like may be used. Further, it is preferable to increase electrical conduction by applying gold plating to the surface of the coil spring 70.
　次に、信号処理部２００について説明する。
　信号処理部２００は、図３および図４に示すように、センサ部１００の圧電素子１０から得られる微弱な電荷である電気信号を少なくとも増幅処理する回路基板部２１と、圧電素子１０に生じた電荷を回路基板部２１まで導く棒状の伝導部材２２と、これら回路基板部２１、伝導部材２２などを覆う覆い部材２３と、回路基板部２１などを密封するＯリング２６と、を備えている。 Next, the signal processing unit 200 will be described.
As shown in FIGS. 3 and 4, the signal processing unit 200 is generated in the piezoelectric element 10 and the circuit board unit 21 that at least amplifies an electric signal that is a weak charge obtained from the piezoelectric element 10 of the sensor unit 100. A rod-shaped conductive member 22 that guides electric charges to the circuit board portion 21, a cover member 23 that covers the circuit board portion 21, the conductive member 22, and the like, and an O-ring 26 that seals the circuit board portion 21 and the like are provided.
　回路基板部２１は、センサ部１００の圧電素子１０から得られる微弱な電荷を増幅するための回路を構成する電子部品などが実装された実装基板２１０を有する。実装基板２１０における先端部には、伝導部材２２における後端部を電気的に接続するための入力側第１接続ピン２１ａと、接地用および位置決め用の入力側第２接続ピン２１ｂとが、半田付けなどにより接続されている。また、実装基板２１０における後端部には、伝送ケーブル８の先端部に設けられたコネクタ８０を介して制御装置６と電気的に接続するための出力側第１接続ピン２１ｃ、出力側第２接続ピン２１ｄおよび出力側第３接続ピン２１ｅが、半田付けなどにより接続されている。そして、出力側第１接続ピン２１ｃは、制御装置６から実装基板２１０への電源電圧（後述する外部電源電圧Ｖｃ）の供給に用いられ、出力側第２接続ピン２１ｄは、実装基板２１０から制御装置６への出力電圧（後述する外部出力電圧Ｖｏ）の供給に用いられ、出力側第３接続ピン２１ｅは、制御装置６から実装基板２１０へのＧＮＤ電圧の供給に用いられる。 The circuit board unit 21 includes a mounting board 210 on which electronic components constituting a circuit for amplifying a weak charge obtained from the piezoelectric element 10 of the sensor unit 100 are mounted. An input side first connection pin 21a for electrically connecting a rear end portion of the conductive member 22 and an input side second connection pin 21b for grounding and positioning are soldered to the front end portion of the mounting substrate 210. Connected by attaching. Further, at the rear end portion of the mounting substrate 210, an output side first connection pin 21 c for electrically connecting to the control device 6 via a connector 80 provided at the front end portion of the transmission cable 8, an output side second portion. The connection pin 21d and the output side third connection pin 21e are connected by soldering or the like. The output-side first connection pin 21c is used to supply a power supply voltage (external power supply voltage Vc described later) from the control device 6 to the mounting board 210, and the output-side second connection pin 21d is controlled from the mounting board 210. The output side third connection pin 21e is used for supplying a GND voltage from the control device 6 to the mounting board 210. The output side third connection pin 21e is used for supplying an output voltage (external output voltage Vo described later) to the device 6.
　伝導部材２２は、棒状（円柱状）の部材であり、先端部には、第２電極部５５の突出部５５ａの先端部が挿入される挿入孔２２ａが形成されている。伝導部材２２における後端部は、回路基板部２１の実装基板２１０に、導線（図示せず）および入力側第１接続ピン２１ａを介して電気的に接続される。伝導部材２２の材質としては、真鍮及びベリリウム銅等を例示することができる。この場合、加工性およびコストの観点からは、真鍮が望ましい。これに対して、電気伝導性、高温強度、信頼性の観点からは、ベリリウム銅が望ましい。 The conductive member 22 is a rod-shaped (columnar) member, and an insertion hole 22a into which the distal end portion of the protruding portion 55a of the second electrode portion 55 is inserted is formed at the distal end portion. The rear end portion of the conductive member 22 is electrically connected to the mounting substrate 210 of the circuit board portion 21 via a conductive wire (not shown) and the input-side first connection pin 21a. Examples of the material of the conductive member 22 include brass and beryllium copper. In this case, brass is desirable from the viewpoint of workability and cost. On the other hand, beryllium copper is desirable from the viewpoints of electrical conductivity, high temperature strength, and reliability.
　覆い部材２３は、伝導部材２２の外周を覆う伝導部材被覆部２３１と、回路基板部２１の実装基板２１０の側面および下面を覆う基板被覆部２３２と、実装基板２１０に接続された出力側第１接続ピン２１ｃ、出力側第２接続ピン２１ｄおよび出力側第３接続ピン２１ｅの周囲を覆うとともに伝送ケーブル８の先端部に設けられたコネクタ８０が嵌め込まれるコネクタ部２３３と、を有している。 The covering member 23 includes a conductive member covering portion 231 that covers the outer periphery of the conductive member 22, a substrate covering portion 232 that covers the side surface and the bottom surface of the mounting substrate 210 of the circuit board portion 21, and a first output side connected to the mounting substrate 210. And a connector portion 233 that covers the periphery of the connection pin 21c, the output-side second connection pin 21d, and the output-side third connection pin 21e, and into which the connector 80 provided at the distal end portion of the transmission cable 8 is fitted.
　伝導部材被覆部２３１は、図３に示すように、中心線方向に沿って延び、伝導部材２２を先端部が露出するように覆っている。
　また、伝導部材被覆部２３１は、先端側から後端側にかけて段階的に外径が異なるように、複数の円筒形状の部分から構成される。具体的には、先端側から後端側にかけて、第１外径を有する第１円筒部２４１と、第１外径よりも小さな第２外径を有する第２円筒部２４２と、第２外径よりも大きな第３外径を有する第３円筒部２４３と、第３外径よりも大きな第４外径を有する第４円筒部２４４とが並んで形成されている。
　第１円筒部２４１における第１外径は、支持部材６５の第３孔６５３の孔径よりも大きく形成されている。これにより、伝導部材被覆部２３１における先端部は、支持部材６５の第３孔６５３を形成する周囲の壁にしまりばめで嵌合（圧入）される。 As shown in FIG. 3, the conductive member covering portion 231 extends along the center line direction and covers the conductive member 22 so that the distal end portion is exposed.
Further, the conductive member covering portion 231 is composed of a plurality of cylindrical portions so that the outer diameters are gradually changed from the front end side to the rear end side. Specifically, a first cylindrical portion 241 having a first outer diameter, a second cylindrical portion 242 having a second outer diameter smaller than the first outer diameter, and a second outer diameter from the front end side to the rear end side. A third cylindrical portion 243 having a larger third outer diameter and a fourth cylindrical portion 244 having a fourth outer diameter larger than the third outer diameter are formed side by side.
The first outer diameter of the first cylindrical portion 241 is formed larger than the hole diameter of the third hole 653 of the support member 65. As a result, the leading end of the conductive member covering portion 231 is fitted (press-fitted) into the surrounding wall forming the third hole 653 of the support member 65 with an interference fit.
　図３に示すように、伝導部材被覆部２３１には、伝導部材被覆部２３１の外周面から突出するとともに、それぞれが中心線方向に延びる複数の凸部２５０が設けられている。本実施の形態では、凸部２５０は、伝導部材被覆部２３１の第２円筒部２４２における先端部に設けられる第１凸部２５１と、伝導部材被覆部２３１の第４円筒部２４４に設けられる第２凸部２５２を有する。
　この例では、第１凸部２５１は、第２円筒部２４２の外周面において、周方向に沿って９０度間隔で４個設けられている。また、第２凸部２５２は、第４円筒部２４４の外周面において、周方向に沿って９０度間隔で４個設けられている。
　なお、この例では、４個の第１凸部２５１は、伝導部材被覆部２３１における第２円筒部２４２と一体的に形成され、４個の第２凸部２５２は、伝導部材被覆部２３１における第４円筒部２４４と一体的に形成されている。 As shown in FIG. 3, the conductive member covering portion 231 is provided with a plurality of convex portions 250 that protrude from the outer peripheral surface of the conductive member covering portion 231 and each extend in the center line direction. In the present embodiment, the convex portion 250 is provided on the first convex portion 251 provided at the distal end portion of the second cylindrical portion 242 of the conductive member covering portion 231 and the fourth cylindrical portion 244 provided on the conductive member covering portion 231. Two convex portions 252 are provided.
In this example, four first convex portions 251 are provided on the outer peripheral surface of the second cylindrical portion 242 at intervals of 90 degrees along the circumferential direction. Further, four second convex portions 252 are provided at intervals of 90 degrees along the circumferential direction on the outer peripheral surface of the fourth cylindrical portion 244.
In this example, the four first convex portions 251 are formed integrally with the second cylindrical portion 242 in the conductive member covering portion 231, and the four second convex portions 252 are formed in the conductive member covering portion 231. It is integrally formed with the fourth cylindrical portion 244.
　信号処理部２００においては、図５に示すように、第２円筒部２４２に設けられた４個の第１凸部２５１が、それぞれ第２ハウジング３２における第２円柱孔３２２を形成する壁に当接する。また、図６に示すように、第４円筒部２４４に設けられた複数の第２凸部２５２が、それぞれ第２ハウジング３２における第４円柱孔３２４を形成する壁に当接する。これにより、伝導部材被覆部２３１が第２ハウジング３２に支持されることになる。 In the signal processing unit 200, as shown in FIG. 5, the four first convex portions 251 provided in the second cylindrical portion 242 respectively contact the wall forming the second cylindrical hole 322 in the second housing 32. Touch. In addition, as shown in FIG. 6, the plurality of second convex portions 252 provided in the fourth cylindrical portion 244 abuts against the wall forming the fourth cylindrical hole 324 in the second housing 32. As a result, the conductive member covering portion 231 is supported by the second housing 32.
　基板被覆部２３２は、基本的には円筒状の部位であり、その側面には、実装基板２１０を内部に設置するための矩形の開口部２３２ａが設けられている。また、基板被覆部２３２における後端側には、ハウジング３０内および実装基板２１０設置部を密封するためのＯリング２６用のリング溝２３２ｂが形成されている。 The substrate covering portion 232 is basically a cylindrical portion, and a rectangular opening 232a for installing the mounting substrate 210 therein is provided on the side surface thereof. A ring groove 232b for the O-ring 26 for sealing the inside of the housing 30 and the mounting board 210 installation portion is formed on the rear end side of the substrate covering portion 232.
　コネクタ部２３３は、基板被覆部２３２における後端側の端面２３２ｃから突出し、実装基板２１０に接続された出力側第１接続ピン２１ｃ、出力側第２接続ピン２１ｄおよび出力側第３接続ピン２１ｅの周囲を覆うように形成された薄肉の部位である。コネクタ部２３３における後端部は開口しており、内部に伝送ケーブル８の先端部に設けられたコネクタ８０を受け入れることが可能になっている。また、コネクタ部２３３における後端側には、内部と外部とを連通する孔２３３ａが形成されており、伝送ケーブル８のコネクタ８０に設けられたフックがこの孔２３３ａに引っ掛ることで、伝送ケーブル８のコネクタ８０がコネクタ部２３３から脱落することが抑制される。 The connector part 233 protrudes from the end face 232c on the rear end side in the board covering part 232, and is connected to the output side first connection pin 21c, the output side second connection pin 21d, and the output side third connection pin 21e connected to the mounting board 210. It is a thin part formed so as to cover the periphery. The rear end portion of the connector portion 233 is open so that the connector 80 provided at the front end portion of the transmission cable 8 can be received therein. Further, a hole 233a that connects the inside and the outside is formed on the rear end side of the connector portion 233, and a hook provided on the connector 80 of the transmission cable 8 is hooked on the hole 233a, so that the transmission cable The eight connectors 80 are prevented from dropping from the connector portion 233.
　以上のように構成された覆い部材２３は、樹脂などの絶縁性を有する材料にて成形されている。また、覆い部材２３は、伝導部材２２、入力側第１接続ピン２１ａ、入力側第２接続ピン２１ｂ、出力側第１接続ピン２１ｃ、出力側第２接続ピン２１ｄおよび出力側第３接続ピン２１ｅとともに一体成形されている。より具体的には、覆い部材２３は、これら伝導部材２２、入力側第１接続ピン２１ａ、入力側第２接続ピン２１ｂ、出力側第１接続ピン２１ｃ、出力側第２接続ピン２１ｄおよび出力側第３接続ピン２１ｅをセットした金型に加熱した樹脂が押し込まれることで成形される。 The covering member 23 configured as described above is formed of an insulating material such as resin. Further, the covering member 23 includes the conductive member 22, the input side first connection pin 21a, the input side second connection pin 21b, the output side first connection pin 21c, the output side second connection pin 21d, and the output side third connection pin 21e. It is integrally molded with it. More specifically, the covering member 23 includes the conductive member 22, the input side first connection pin 21a, the input side second connection pin 21b, the output side first connection pin 21c, the output side second connection pin 21d, and the output side. Molded by pressing the heated resin into the mold on which the third connection pin 21e is set.
　信号処理部２００をユニット化するにあたっては、成形された覆い部材２３の開口部２３２ａから、回路基板部２１の実装基板２１０を挿入し、基板被覆部２３２の中央部に設置する。実装基板２１０を設置する際、板厚方向に貫通されたスルーホールに、入力側第１接続ピン２１ａ、入力側第２接続ピン２１ｂ、出力側第１接続ピン２１ｃ、出力側第２接続ピン２１ｄおよび出力側第３接続ピン２１ｅの各先端を通し、半田付けする。その後、入力側第１接続ピン２１ａと伝導部材２２とを導線を用いて接続する。また、覆い部材２３の基板被覆部２３２のリング溝２３２ｂにＯリング２６を装着する。Ｏリング２６は、フッ素系ゴムからなる周知のＯ状のリングである。 When unitizing the signal processing unit 200, the mounting substrate 210 of the circuit board unit 21 is inserted from the opening 232 a of the formed covering member 23 and installed at the center of the substrate covering unit 232. When the mounting substrate 210 is installed, the input side first connection pin 21a, the input side second connection pin 21b, the output side first connection pin 21c, and the output side second connection pin 21d are inserted into the through holes penetrating in the plate thickness direction. And each tip of the output side third connection pin 21e is passed through and soldered. Then, the input side 1st connection pin 21a and the conduction member 22 are connected using a conducting wire. Further, the O-ring 26 is attached to the ring groove 232 b of the substrate covering portion 232 of the covering member 23. The O-ring 26 is a well-known O-shaped ring made of fluorine-based rubber.
　次に、保持部材３００について説明する。
　保持部材３００は、薄肉円筒状の部材であり、図４に示すように、後端部に内周面から内側に突出した突出部３００ａが設けられている。保持部材３００は、第２ハウジング３２に装着された後、外部から、第５外周面３３５に設けられた凹部３３５ａに対応する部位が加圧されることでかしめられる。これにより、保持部材３００は、ハウジング３０に対して移動し難くなり、信号処理部２００がハウジング３０に対して移動することを抑制している。 Next, the holding member 300 will be described.
The holding member 300 is a thin cylindrical member, and as shown in FIG. 4, a protruding portion 300 a that protrudes inward from the inner peripheral surface is provided at the rear end portion. After the holding member 300 is mounted on the second housing 32, the holding member 300 is caulked by pressurizing a portion corresponding to the concave portion 335 a provided in the fifth outer peripheral surface 335 from the outside. Thereby, the holding member 300 becomes difficult to move with respect to the housing 30, and the signal processing unit 200 is prevented from moving with respect to the housing 30.
　続いて、信号処理部２００の回路基板部２１における実装基板２１０の構成について説明を行う。図７は、実装基板２１０における回路構成図を示している。
　本実施の形態の実装基板２１０は、１または複数の電子部品（回路素子）を実装するための配線（回路パターン）が形成されたプリント配線基板２１１を備えている。また、この実装基板２１０は、プリント配線基板２１１に実装された、保護回路２１２と、積分回路２１３と、増幅回路２１４と、直流遮断回路２１５と、電源回路（Ｖｒｅｇ）２１６とをさらに備える。なお、本実施の形態では、積分回路２１３、増幅回路２１４および電源回路２１６が、信号処理回路としての機能を有しており、直流遮断回路２１５が直流抑制部としての機能を有している。 Next, the configuration of the mounting substrate 210 in the circuit board unit 21 of the signal processing unit 200 will be described. FIG. 7 shows a circuit configuration diagram of the mounting substrate 210.
The mounting board 210 of this embodiment includes a printed wiring board 211 on which wiring (circuit pattern) for mounting one or a plurality of electronic components (circuit elements) is formed. The mounting board 210 further includes a protection circuit 212, an integration circuit 213, an amplification circuit 214, a DC cutoff circuit 215, and a power supply circuit (Vreg) 216 mounted on the printed wiring board 211. In this embodiment, the integration circuit 213, the amplification circuit 214, and the power supply circuit 216 have a function as a signal processing circuit, and the DC cutoff circuit 215 has a function as a DC suppression unit.
　本実施の形態の実装基板２１０では、圧電素子１０から保護回路２１２を介して入力されてくる検出信号の一例としての電荷信号を、積分回路２１３で積分することで電圧信号に変換し、変換後の電圧信号を増幅回路２１４で増幅して外部（例えば図１に示す制御装置６）に出力している。この間、電源回路２１６は、積分回路２１３および増幅回路２１４で使用する電源電圧（後述する内部出力電圧Ｖｉ）の作成および出力を行う。また、直流遮断回路２１５は、実装基板２１０における接地側から、実装基板２１０の接地対象であるハウジング３０（より具体的には第２ハウジング３２）に向かう、直流電流を遮断している。 In the mounting substrate 210 of the present embodiment, a charge signal as an example of a detection signal input from the piezoelectric element 10 via the protection circuit 212 is converted into a voltage signal by integration by the integration circuit 213, and after the conversion Are amplified by the amplification circuit 214 and output to the outside (for example, the control device 6 shown in FIG. 1). During this time, the power supply circuit 216 creates and outputs a power supply voltage (an internal output voltage Vi described later) used in the integration circuit 213 and the amplifier circuit 214. Further, the DC cutoff circuit 215 blocks a DC current from the ground side of the mounting board 210 toward the housing 30 (more specifically, the second housing 32) that is the grounding target of the mounting board 210.
　本実施の形態では、プリント配線基板２１１としてガラス布基材エポキシ樹脂をベースとした所謂ガラエポ基板を用いている。そして、プリント配線基板２１１には、入出力用の端子として、入力信号端子２１１ａ、入力接地端子２１１ｂ、電源端子２１１ｃ、出力信号端子２１１ｄおよび出力接地端子２１１ｅが設けられている。これらのうち、入力信号端子２１１ａは、入力側第１接続ピン２１ａ、伝導部材２２、コイルスプリング７０および第２電極部５５を介して、圧電素子１０の後端側の端面に接続される。また、入力接地端子２１１ｂは、入力側第２接続ピン２１ｂを介して第２ハウジング３２に接続される。さらに、電源端子２１１ｃは、出力側第１接続ピン２１ｃおよびコネクタ８０を介して第１ケーブル８１（図２参照）に接続される。さらにまた、出力信号端子２１１ｄは、出力側第１接続ピン２１ｃおよびコネクタ８０を介して第２ケーブル８２（図２参照）に接続される。そして、出力接地端子２１１ｅは、出力側第３接続ピン２１ｅおよびコネクタ８０を介して第３ケーブル８３（図２参照）に接続される。なお、入力接地端子２１１ｂおよび出力接地端子２１１ｅは、プリント配線基板２１１に設けられた配線および直流遮断回路２１５（コンデンサ）を介して互いに接続されている。 In the present embodiment, a so-called glass epoxy substrate based on a glass cloth base epoxy resin is used as the printed wiring board 211. The printed circuit board 211 is provided with an input signal terminal 211a, an input ground terminal 211b, a power supply terminal 211c, an output signal terminal 211d, and an output ground terminal 211e as input / output terminals. Among these, the input signal terminal 211 a is connected to the end face on the rear end side of the piezoelectric element 10 through the input side first connection pin 21 a, the conductive member 22, the coil spring 70, and the second electrode portion 55. The input ground terminal 211b is connected to the second housing 32 via the input-side second connection pin 21b. Further, the power terminal 211c is connected to the first cable 81 (see FIG. 2) via the output-side first connection pin 21c and the connector 80. Furthermore, the output signal terminal 211d is connected to the second cable 82 (see FIG. 2) via the output-side first connection pin 21c and the connector 80. The output ground terminal 211e is connected to the third cable 83 (see FIG. 2) via the output-side third connection pin 21e and the connector 80. The input ground terminal 211b and the output ground terminal 211e are connected to each other via a wiring provided on the printed wiring board 211 and a DC cutoff circuit 215 (capacitor).
　保護回路２１２は、ダイオードで構成されており、入力接地端子２１１ｂ側にアノードが接続され、電源端子２１１ｃ側にカソードが接続される。 The protection circuit 212 is composed of a diode, and an anode is connected to the input ground terminal 211b side and a cathode is connected to the power supply terminal 211c side.
　積分回路２１３は、第１演算増幅器ＯＰ１と、積分用コンデンサＣ１と、帰還抵抗Ｒ１とを備える。積分回路２１３において、第１演算増幅器ＯＰ１の反転入力端子は、入力信号端子２１１ａに接続される。また、第１演算増幅器ＯＰ１の非反転入力端子は、電源回路２１６の出力端（ｏｕｔ）に接続される。さらに、第１演算増幅器ＯＰ１の出力端子は、増幅回路２１４に設けられた第２演算増幅器ＯＰ２（詳細は後述する）の非反転入力端子に接続される。さらにまた、積分用コンデンサＣ１の一端は、第１演算増幅器ＯＰ１の反転入力端子に接続され、積分用コンデンサＣ１の他端は、第１演算増幅器ＯＰ１の出力端子に接続される。そして、帰還抵抗Ｒ１の一端は、第１演算増幅器ＯＰ１の反転入力端子に接続され、帰還抵抗Ｒ１の他端は、第１演算増幅器ＯＰ１の出力端子に接続される。したがって、積分用コンデンサＣ１および帰還抵抗Ｒ１は、第１演算増幅器ＯＰ１の反転入力端子および出力端子に対し、並列に接続されている。 The integrating circuit 213 includes a first operational amplifier OP1, an integrating capacitor C1, and a feedback resistor R1. In the integrating circuit 213, the inverting input terminal of the first operational amplifier OP1 is connected to the input signal terminal 211a. Further, the non-inverting input terminal of the first operational amplifier OP1 is connected to the output terminal (out) of the power supply circuit 216. Further, the output terminal of the first operational amplifier OP1 is connected to a non-inverting input terminal of a second operational amplifier OP2 (details will be described later) provided in the amplifier circuit 214. Furthermore, one end of the integrating capacitor C1 is connected to the inverting input terminal of the first operational amplifier OP1, and the other end of the integrating capacitor C1 is connected to the output terminal of the first operational amplifier OP1. One end of the feedback resistor R1 is connected to the inverting input terminal of the first operational amplifier OP1, and the other end of the feedback resistor R1 is connected to the output terminal of the first operational amplifier OP1. Therefore, the integrating capacitor C1 and the feedback resistor R1 are connected in parallel to the inverting input terminal and the output terminal of the first operational amplifier OP1.
　増幅回路２１４は、第２演算増幅器ＯＰ２と、第１設定抵抗Ｒ２ａと、第２設定抵抗Ｒ２ｂとを備える。増幅回路２１４において、第２演算増幅器ＯＰ２の反転入力端子は、第１設定抵抗Ｒ２ａを介して、電源回路２１６の出力端（ｏｕｔ）に接続される。また、第２演算増幅器ＯＰ２の非反転入力端子は、積分回路２１３に設けられた第１演算増幅器ＯＰ１の出力端子に接続される。さらに、第２演算増幅器ＯＰ２の出力端子は、出力信号端子２１１ｄに接続される。さらにまた、第２設定抵抗Ｒ２ｂの一端は、第２演算増幅器ＯＰ２の反転入力端子に接続され、第２設定抵抗Ｒ２ｂの他端は、第２演算増幅器ＯＰ２の出力端子に接続される。 The amplifier circuit 214 includes a second operational amplifier OP2, a first setting resistor R2a, and a second setting resistor R2b. In the amplifier circuit 214, the inverting input terminal of the second operational amplifier OP2 is connected to the output terminal (out) of the power supply circuit 216 via the first setting resistor R2a. The non-inverting input terminal of the second operational amplifier OP2 is connected to the output terminal of the first operational amplifier OP1 provided in the integrating circuit 213. Further, the output terminal of the second operational amplifier OP2 is connected to the output signal terminal 211d. Furthermore, one end of the second setting resistor R2b is connected to the inverting input terminal of the second operational amplifier OP2, and the other end of the second setting resistor R2b is connected to the output terminal of the second operational amplifier OP2.
　直流遮断回路２１５は、コンデンサで構成されており、入力接地端子２１１ｂに一端が接続され、保護回路２１２を構成するダイオードにおけるアノード側に他端が接続される。なお、この例では、直流遮断回路２１５として、１μＦの容量を有するコンデンサを用いている。 The DC cut-off circuit 215 is composed of a capacitor, one end is connected to the input ground terminal 211b, and the other end is connected to the anode side of the diode constituting the protection circuit 212. In this example, a capacitor having a capacity of 1 μF is used as the DC cutoff circuit 215.
　電源回路２１６は、その入力端（ｉｎ）が、電源端子２１１ｃに接続され、その出力端（ｏｕｔ）が、積分回路２１３（より具体的には積分回路２１３に設けられた第１演算増幅器ＯＰ１の非反転入力端子）および増幅回路２１４（より具体的には増幅回路２１４に設けられた第１設定抵抗Ｒ２ａ）に接続され、その接地端（ＧＮＤ）が、出力接地端子２１１ｅに接続され、且つ、直流遮断回路２１５を介して入力接地端子２１１ｂに接続される。 The power supply circuit 216 has an input terminal (in) connected to the power supply terminal 211c and an output terminal (out) connected to the integration circuit 213 (more specifically, the first operational amplifier OP1 provided in the integration circuit 213). A non-inverting input terminal) and an amplifier circuit 214 (more specifically, a first setting resistor R2a provided in the amplifier circuit 214), and a ground terminal (GND) thereof is connected to the output ground terminal 211e, and It is connected to the input ground terminal 211b via the DC cutoff circuit 215.
　本実施の形態の実装基板２１０において、入力信号端子２１１ａには、圧電素子１０より、入力信号（電荷信号）として入力電荷Ｑｉが入力される。また、電源端子２１１ｃには、制御装置６から、定電圧の一例としての外部電源電圧Ｖｃ（この例ではＤＣ＋５．０Ｖ）が印加される。さらに、出力信号端子２１１ｄからは、制御装置６に向けて、出力信号の一例としての外部出力電圧Ｖｏが出力される。そして、入力接地端子２１１ｂおよび出力接地端子２１１ｅは、それぞれ、実装基板２１０の外部に設けられた接地体に接続されることにより、グランド電位（ＧＮＤ電位）に設定される。 In the mounting substrate 210 of the present embodiment, the input charge Qi is input from the piezoelectric element 10 to the input signal terminal 211a as an input signal (charge signal). An external power supply voltage Vc (an example of DC + 5.0 V in this example) is applied from the control device 6 to the power supply terminal 211c. Further, an external output voltage Vo as an example of an output signal is output from the output signal terminal 211 d to the control device 6. The input ground terminal 211b and the output ground terminal 211e are set to the ground potential (GND potential) by being connected to a ground body provided outside the mounting substrate 210, respectively.
　また、積分回路２１３は、圧電素子１０から入力されてくる入力電荷Ｑｉを積分し、得られた内部出力電圧Ｖｉを増幅回路２１４に向けて出力する。このとき、第１演算増幅器ＯＰ１の反転入力端子には、入力信号端子２１１ａから入力電荷Ｑｉが供給される。一方、第１演算増幅器ＯＰ１の非反転入力端子には、電源回路２１６から基準電圧となる内部電源電圧Ｖｒが印加される。このように、本実施の形態の積分回路２１３は、第１演算増幅器ＯＰ１を用いた積分回路として構成されている。ただし、第１演算増幅器ＯＰ１の非反転入力端子は、ＧＮＤ電位に設定される（接地される）のではなく、内部電源電圧Ｖｒに設定される。これは、第１演算増幅器ＯＰ１が単電源で動作する（詳細は後述する）ことと、入力電荷Ｑｉが正負両方の値をとり得ることとを理由とするものである。 Further, the integrating circuit 213 integrates the input charge Qi input from the piezoelectric element 10 and outputs the obtained internal output voltage Vi to the amplifying circuit 214. At this time, the input charge Qi is supplied from the input signal terminal 211a to the inverting input terminal of the first operational amplifier OP1. On the other hand, an internal power supply voltage Vr serving as a reference voltage is applied from the power supply circuit 216 to the non-inverting input terminal of the first operational amplifier OP1. As described above, the integration circuit 213 of the present embodiment is configured as an integration circuit using the first operational amplifier OP1. However, the non-inverting input terminal of the first operational amplifier OP1 is not set to the GND potential (grounded) but is set to the internal power supply voltage Vr. This is because the first operational amplifier OP1 operates with a single power supply (details will be described later) and that the input charge Qi can take both positive and negative values.
　増幅回路２１４は、積分回路２１３から入力されてくる内部出力電圧Ｖｉを増幅し、得られた外部出力電圧Ｖｏを外部（例えば図１に示す制御装置６）に向けて出力する。このとき、第２演算増幅器ＯＰ２の反転入力端子には、電源回路２１６から出力される内部電源電圧Ｖｒが、第１設定抵抗Ｒ２ａを介して印加される。また、第２演算増幅器ＯＰ２の反転入力端子には、第２演算増幅器ＯＰ２の出力端子から出力される外部出力電圧Ｖｏが、第２設定抵抗Ｒ２ｂを介して印加される。一方、第２演算増幅器ＯＰ２の非反転入力端子には、積分回路２１３における第１演算増幅器ＯＰ１の出力端子から出力される内部出力電圧Ｖｉが印加される。このように、本実施の形態の増幅回路２１４は、第２演算増幅器ＯＰ２を用いた反転増幅回路として構成されている。 The amplifying circuit 214 amplifies the internal output voltage Vi input from the integrating circuit 213, and outputs the obtained external output voltage Vo to the outside (for example, the control device 6 shown in FIG. 1). At this time, the internal power supply voltage Vr output from the power supply circuit 216 is applied to the inverting input terminal of the second operational amplifier OP2 via the first setting resistor R2a. The external output voltage Vo output from the output terminal of the second operational amplifier OP2 is applied to the inverting input terminal of the second operational amplifier OP2 via the second setting resistor R2b. On the other hand, the internal output voltage Vi output from the output terminal of the first operational amplifier OP1 in the integrating circuit 213 is applied to the non-inverting input terminal of the second operational amplifier OP2. As described above, the amplifier circuit 214 of the present embodiment is configured as an inverting amplifier circuit using the second operational amplifier OP2.
　電源回路２１６は、電源端子２１１ｃを介して入力されてくる外部電源電圧Ｖｃ（この例ではＤＣ＋５．０Ｖ）を、より低い内部電源電圧Ｖｒ（この例ではＤＣ＋１．０Ｖ）に変換して出力する。なお、電源回路２１６における回路構成の詳細については後述する。 The power supply circuit 216 converts the external power supply voltage Vc (DC + 5.0V in this example) input via the power supply terminal 211c into a lower internal power supply voltage Vr (DC + 1.0V in this example) and outputs the converted voltage. Details of the circuit configuration of the power supply circuit 216 will be described later.
　ここで、積分回路２１３に設けられた第１演算増幅器ＯＰ１および増幅回路２１４に設けられた第２演算増幅器ＯＰ２は、それぞれ、ＤＣ＋５．０Ｖの単電源で動作するものを用いている。これら第１演算増幅器ＯＰ１、第２演算増幅器ＯＰ２のそれぞれにおいて、正電源端子（図示せず）は、図示しない配線を介して電源端子２１１ｃに接続されており、負電源端子（図示せず）は、図示しない配線を介して出力接地端子２１１ｅに接続されている。したがって、これら第１演算増幅器ＯＰ１、第２演算増幅器ＯＰ２には、それぞれ、動作電圧としてＤＣ＋５．０Ｖが供給されることになる。 Here, the first operational amplifier OP1 provided in the integrating circuit 213 and the second operational amplifier OP2 provided in the amplifying circuit 214 are each operated by a single power source of DC + 5.0V. In each of the first operational amplifier OP1 and the second operational amplifier OP2, a positive power supply terminal (not shown) is connected to a power supply terminal 211c via a wiring not shown, and a negative power supply terminal (not shown) is connected. The output ground terminal 211e is connected via a wiring (not shown). Therefore, DC + 5.0V is supplied as an operating voltage to each of the first operational amplifier OP1 and the second operational amplifier OP2.
　図８は、実装基板２１０に設けられた電源回路２１６の回路構成図を示している。
　電源回路２１６は、外部出力電圧Ｖｏを分圧して内部電源電圧Ｖｒを得るための分圧回路２１６１と、得られた内部電源電圧Ｖｒを安定させるためのボルテージフォロワ回路２１６２とを備えている。 FIG. 8 shows a circuit configuration diagram of the power supply circuit 216 provided on the mounting substrate 210.
The power supply circuit 216 includes a voltage dividing circuit 2161 for dividing the external output voltage Vo to obtain the internal power supply voltage Vr, and a voltage follower circuit 2162 for stabilizing the obtained internal power supply voltage Vr.
　分圧回路２１６１は、一端が電源回路２１６の入力端（ｉｎ）に接続される第１分圧抵抗Ｒ３ａと、一端が第１分圧抵抗Ｒ３ａの他端に接続されるとともに他端が電源回路２１６の接地端（ＧＮＤ）に接続される第２分圧抵抗Ｒ３ｂとを有している。本実施の形態では、電源回路２１６の入力端（ｉｎ）と接地端（ＧＮＤ）との間に印加される外部出力電圧Ｖｏを、第１分圧抵抗Ｒ３ａにおいて降下電圧Ｖｄだけ電圧降下させ且つ第２分圧抵抗Ｒ３ｂにおいて内部電源電圧Ｖｒだけ電圧降下させるように（Ｖｏ＝Ｖｄ＋Ｖｒ）、第１分圧抵抗Ｒ３ａおよび第２分圧抵抗Ｒ３ｂの各抵抗値を設定している。そして、分圧回路２１６１における第１分圧抵抗Ｒ３ａおよび第２分圧抵抗Ｒ３ｂの接続端は、ボルテージフォロワ回路２１６２に設けられた第３演算増幅器ＯＰ３（詳細は後述する）の非反転入力端子に接続される。 The voltage dividing circuit 2161 has one end connected to the input terminal (in) of the power supply circuit 216 and one end connected to the other end of the first voltage dividing resistor R3a and the other end connected to the power supply circuit. And a second voltage dividing resistor R3b connected to the ground terminal (GND) of 216. In the present embodiment, the external output voltage Vo applied between the input terminal (in) and the ground terminal (GND) of the power supply circuit 216 is dropped by the drop voltage Vd in the first voltage dividing resistor R3a, and The resistance values of the first voltage dividing resistor R3a and the second voltage dividing resistor R3b are set so that the voltage is dropped by the internal power supply voltage Vr in the two voltage dividing resistor R3b (Vo = Vd + Vr). The connection end of the first voltage dividing resistor R3a and the second voltage dividing resistor R3b in the voltage dividing circuit 2161 is connected to a non-inverting input terminal of a third operational amplifier OP3 (details will be described later) provided in the voltage follower circuit 2162. Connected.
　ボルテージフォロワ回路２１６２は、第３演算増幅器ＯＰ３を有している。ここで、第３演算増幅器ＯＰ３の非反転入力端子は、分圧回路２１６１の接続端に接続される。また、第３演算増幅器ＯＰ３の出力端子は、電源回路２１６の出力端（ｏｕｔ）および第３演算増幅器ＯＰ３の反転入力端子に接続される。 The voltage follower circuit 2162 has a third operational amplifier OP3. Here, the non-inverting input terminal of the third operational amplifier OP3 is connected to the connection end of the voltage dividing circuit 2161. The output terminal of the third operational amplifier OP3 is connected to the output terminal (out) of the power supply circuit 216 and the inverting input terminal of the third operational amplifier OP3.
　ここで、上述した圧力検出装置５における電気的な接続構造について説明する。
　先ず、圧電素子１０における先端側の端面は、金属製の第１電極部５０およびダイアフラムヘッド４０を介して、金属製のハウジング３０と電気的に接続される。 Here, the electrical connection structure in the pressure detection apparatus 5 mentioned above is demonstrated.
First, the end face on the front end side of the piezoelectric element 10 is electrically connected to the metal housing 30 via the metal first electrode portion 50 and the diaphragm head 40.
　これに対し、圧電素子１０における後端側の端面は、金属製の第２電極部５５と電気的に接続され、第２電極部５５は、突出部５５ａを介して金属製のコイルスプリング７０と電気的に接続される。また、コイルスプリング７０は、金属製の伝導部材２２と電気的に接続され、伝導部材２２は、入力側第１接続ピン２１ａを介して実装基板２１０の入力信号端子２１１ａと電気的に接続される。他方、第２電極部５５の突出部５５ａの外径は支持部材６５の第１孔６５１の孔径よりも小さく、伝導部材２２における先端部の外径は支持部材６５の第２孔６５２の孔径よりも小さい。つまり、第２電極部５５、コイルスプリング７０および伝導部材２２は、支持部材６５と直接接触していないために、電気的に接続されていない。それゆえ、第２電極部５５からコイルスプリング７０および伝導部材２２を介して実装基板２１０へと至る電荷信号の伝送経路は、それぞれが絶縁体で構成された、絶縁リング６０および覆い部材２３によって、金属製のハウジング３０と電気的に絶縁される。 On the other hand, the end surface on the rear end side of the piezoelectric element 10 is electrically connected to the metal second electrode portion 55, and the second electrode portion 55 is connected to the metal coil spring 70 via the protruding portion 55 a. Electrically connected. The coil spring 70 is electrically connected to the metal conductive member 22, and the conductive member 22 is electrically connected to the input signal terminal 211 a of the mounting substrate 210 via the input-side first connection pin 21 a. . On the other hand, the outer diameter of the protrusion 55 a of the second electrode portion 55 is smaller than the hole diameter of the first hole 651 of the support member 65, and the outer diameter of the tip portion of the conductive member 22 is larger than the hole diameter of the second hole 652 of the support member 65. Is also small. That is, the second electrode portion 55, the coil spring 70, and the conductive member 22 are not electrically connected because they are not in direct contact with the support member 65. Therefore, the charge signal transmission path from the second electrode portion 55 to the mounting substrate 210 via the coil spring 70 and the conductive member 22 is formed by the insulating ring 60 and the covering member 23 each made of an insulator. It is electrically insulated from the metal housing 30.
　また、実装基板２１０の入力接地端子２１１ｂは、入力側第２接続ピン２１ｂを介して第２ハウジング３２（ハウジング３０）と電気的に接続される。さらに、実装基板２１０の電源端子２１１ｃは、出力側第１接続ピン２１ｃを介して第１ケーブル８１と電気的に接続される。さらにまた、実装基板２１０の出力信号端子２１１ｄは、出力側第２接続ピン２１ｄを介して第２ケーブル８２と電気的に接続される。そして、実装基板２１０の出力接地端子２１１ｅは、出力側第３接続ピン２１ｅを介して、第３ケーブル８３と電気的に接続される。 In addition, the input ground terminal 211b of the mounting substrate 210 is electrically connected to the second housing 32 (housing 30) via the input-side second connection pin 21b. Furthermore, the power supply terminal 211c of the mounting substrate 210 is electrically connected to the first cable 81 via the output-side first connection pin 21c. Furthermore, the output signal terminal 211d of the mounting substrate 210 is electrically connected to the second cable 82 via the output-side second connection pin 21d. The output ground terminal 211e of the mounting substrate 210 is electrically connected to the third cable 83 via the output-side third connection pin 21e.
　以上のように構成された圧力検出装置５をシリンダヘッド４に装着する際には、センサ部１００のダイアフラムヘッド４０の方から先にシリンダヘッド４に形成された連通孔４ａに挿入していき、ハウジング３０の第２ハウジング３２に形成された雄ねじ３３２ａをシリンダヘッド４の連通孔４ａに形成された雌ねじ４ｅにねじ込む。
　圧力検出装置５をシリンダヘッド４に装着することにより、ハウジング３０は、金属製のシリンダヘッド４と電気的に接続される。このシリンダヘッド４は、電気的に接地された状態にあるため、圧力検出装置５では、ハウジング３０を介して、圧電素子１０における先端部が接地される。ここで、この例では、圧電素子１０の側面とハウジング３０の内壁面とが接触し得る構造になっているが、圧電素子１０が絶縁体で構成されていることにより抵抗値が極めて大きいことと、圧力変化に伴って発生する電荷が、圧電素子１０における中心線方向の両端部に発生することとにより、特に問題とはならない。 When the pressure detecting device 5 configured as described above is attached to the cylinder head 4, the diaphragm head 40 of the sensor unit 100 is inserted into the communication hole 4a formed in the cylinder head 4 first, The male screw 332 a formed in the second housing 32 of the housing 30 is screwed into the female screw 4 e formed in the communication hole 4 a of the cylinder head 4.
By mounting the pressure detection device 5 on the cylinder head 4, the housing 30 is electrically connected to the metal cylinder head 4. Since the cylinder head 4 is in a state of being electrically grounded, in the pressure detection device 5, the tip portion of the piezoelectric element 10 is grounded via the housing 30. Here, in this example, the side surface of the piezoelectric element 10 and the inner wall surface of the housing 30 are in contact with each other, but the resistance value is extremely large because the piezoelectric element 10 is made of an insulator. The electric charge generated with the pressure change is generated at both ends of the piezoelectric element 10 in the center line direction.
　次に、図１等に示すシール部材７について説明する。
　シール部材７は、図２に示すように、シリンダヘッド４における連通孔４ａを形成する周囲の壁のセンサ部１００締め付け方向の端面と、圧力検出装置５のハウジング３０の第３外周面３３３と第４外周面３３４とを接続する接続面との間に配置された第１シール部材７１を有している。また、シール部材７は、シリンダヘッド４の連通孔４ａの傾斜部４ｃと、圧力検出装置５のハウジング３０の第１ハウジング３１の傾斜面３１５ａとの間に配置された第２シール部材７２を有している。 Next, the seal member 7 shown in FIG.
As shown in FIG. 2, the seal member 7 includes an end surface of the surrounding wall forming the communication hole 4 a in the cylinder head 4 in the tightening direction of the sensor unit 100, a third outer peripheral surface 333 of the housing 30 of the pressure detection device 5, It has the 1st seal member 71 arrange | positioned between the connection surfaces which connect 4 outer peripheral surface 334. FIG. In addition, the seal member 7 has a second seal member 72 disposed between the inclined portion 4c of the communication hole 4a of the cylinder head 4 and the inclined surface 315a of the first housing 31 of the housing 30 of the pressure detection device 5. is doing.
　続いて、圧力検出装置５とともに、内燃機関１の圧力検出システムを構成する制御装置６について説明する。図９は、制御装置６の構成を説明するための図である。ここで、図９（ａ）は制御装置６のハードウェア構成を説明するためのブロック図であり、図９（ｂ）は制御装置６における給電系統を説明するための図である。なお、制御装置６は、ＥＣＵ（Engine Control Unit）と呼ばれることがある。 Subsequently, the control device 6 constituting the pressure detection system of the internal combustion engine 1 together with the pressure detection device 5 will be described. FIG. 9 is a diagram for explaining the configuration of the control device 6. Here, FIG. 9A is a block diagram for explaining the hardware configuration of the control device 6, and FIG. 9B is a diagram for explaining a power feeding system in the control device 6. In addition, the control apparatus 6 may be called ECU (Engine | Control * Unit).
　供給／処理部の一例としての制御装置６は、圧力検出装置５など、内燃機関１を搭載した装置（例えば自動車）に設けられた各種機器から出力される信号（圧力検出装置５の場合は外部出力電圧Ｖｏ）の入力を受け付ける入力受付部６１と、入力受付部６１を介して入力される各種信号に基づいて制御量を演算するＭＣＵ（Micro Control Unit）６２と、ＭＣＵ６２による演算結果に基づき、電源停止後においても記憶させておくべきデータを記憶するＥＥＰＲＯＭ（Electrically Erasable Programmable Read-Only Memory）６３と、ＭＣＵ６２による演算結果に基づき、各種機器に対して制御のための駆動信号を出力する駆動信号出力部６４と、同じ装置内に設けられた他の制御装置と通信を行う通信部６７と、制御装置６の内部に設けられた各部（ＭＣＵ６２等）を動作させるために必要な電力を供給するとともに、制御装置６の外部に設けられた各種機器（圧力検出装置５等）を動作させるために必要な電力を供給する電源部６６とを備えている。 The control device 6 as an example of the supply / processing unit includes signals output from various devices provided in a device (for example, an automobile) in which the internal combustion engine 1 is mounted, such as the pressure detection device 5 (in the case of the pressure detection device 5, an external device). Based on the calculation result of the input receiving unit 61 that receives the input of the output voltage Vo), the MCU (Micro Control Unit) 62 that calculates the control amount based on various signals input via the input receiving unit 61, An EEPROM (Electrically-Erasable-Programmable-Read-Only Memory) 63 that stores data that should be stored even after the power is stopped, and a drive signal that outputs a drive signal for control to various devices based on the calculation result by the MCU 62 The output unit 64, a communication unit 67 that communicates with other control devices provided in the same device, and each unit (MCU provided in the control device 6) And a power supply unit 66 for supplying power necessary for operating various devices (such as the pressure detecting device 5) provided outside the control device 6. I have.
　入力受付部６１は、外部から入力されてくるアナログ信号にＡ／Ｄ変換を施してデジタル信号を作成したり、外部から入力されてくるデジタル信号にゲイン調整を施したりすることで、外部からの入力信号をＭＣＵ６２で使用可能な状態に変換する。なお、この例において、圧力検出装置５から入力受付部６１に入力される外部出力電圧Ｖｏは、アナログ信号である。 The input receiving unit 61 performs A / D conversion on an analog signal input from the outside to create a digital signal, or performs gain adjustment on the digital signal input from the outside, thereby allowing an input from the outside. The input signal is converted into a state usable by the MCU 62. In this example, the external output voltage Vo input from the pressure detection device 5 to the input receiving unit 61 is an analog signal.
　ＭＣＵ６２は、所謂ワンチップマイコンで構成されており、各種演算処理を行うＭＰＵ（Micro-Processing Unit）、ＭＰＵが実行するプログラムを格納するＲＯＭ（Read Only　Memory）、ＭＰＵによるプログラムの実行において一時的に発生するデータを記憶するＲＡＭ（Random Access Memory）等を内蔵している。 The MCU 62 is configured by a so-called one-chip microcomputer, and temporarily executes MPU (Micro-Processing Unit) that performs various arithmetic processing, ROM (Read Only Memory) that stores a program executed by the MPU, and program execution by the MPU. Built-in RAM (Random Access Memory) for storing generated data.
　ＥＥＰＲＯＭ６３は、電源供給を行わなくても、記憶しているデータが消えない特性を有する不揮発性メモリである。そして、制御装置６に設けられたＥＥＰＲＯＭ６３は、例えば、内燃機関１を搭載する装置の起動時に実行される故障診断の結果や、内燃機関１の動作において生じた不具合等に関するデータを記憶する。 The EEPROM 63 is a non-volatile memory having a characteristic that stored data does not disappear even if power is not supplied. The EEPROM 63 provided in the control device 6 stores, for example, data on the result of failure diagnosis executed when the device equipped with the internal combustion engine 1 is started, and troubles occurring in the operation of the internal combustion engine 1.
　駆動信号出力部６４は、ＭＣＵ６２から入力されてくる演算結果としてのデジタル信号にＤ/Ａ変換を施してアナログ信号を作成したり、ＭＣＵ６２から入力されてくる演算結果としてのデジタル信号にゲイン調整を施したりすることで、ＭＣＵ６２からの出力信号を外部に設けられた各種機器にて使用可能な状態に変換する。 The drive signal output unit 64 performs D / A conversion on the digital signal as the calculation result input from the MCU 62 to create an analog signal, or adjusts the gain of the digital signal as the calculation result input from the MCU 62. By performing this, the output signal from the MCU 62 is converted into a state usable by various devices provided outside.
　通信部６７は、他の制御装置から受信した通信信号を、ＭＣＵ６２で処理できるレベルに変換する。また、ＭＣＵ６２から入力されてくるデジタル信号を、他の制御装置との間の通信規格に適した通信信号に変換する。 The communication unit 67 converts a communication signal received from another control device to a level that can be processed by the MCU 62. Moreover, the digital signal input from MCU62 is converted into the communication signal suitable for the communication standard between other control apparatuses.
　電源部６６は、内燃機関１が搭載された装置に設けられた外部電源（例えば自動車の場合はバッテリ）を介して入力されてくるバッテリ電圧Ｖｂ（この例ではＤＣ＋１２Ｖ）を、より低い動作電圧に変換して、制御装置６を構成するＭＣＵ６２等に供給する。また、電源部６６は、入力されてくるバッテリ電圧Ｖｂを、より低い外部電源電圧Ｖｃに変換して、制御装置６の外部に設けられた圧力検出装置５等に出力する。さらに、電源部６６の接地端（ＧＮＤ）は、外部（例えば図１に示す内燃機関１のシリンダブロック２）に接続されている。これにより、制御装置６を構成する各部（ＭＣＵ６２等）は、電源部６６の接地端（ＧＮＤ）の電位を基準（グランド）として動作する。なお、電源部６６が出力する動作電圧および外部電源電圧Ｖｃは、同じ大きさであってもよいし、異なる大きさであってもかまわない。 The power supply unit 66 converts the battery voltage Vb (in this example, DC + 12V) input via an external power supply (for example, a battery in the case of an automobile) provided in a device on which the internal combustion engine 1 is mounted, to a lower operating voltage. It converts and supplies to MCU62 grade | etc., Which comprises the control apparatus 6. FIG. In addition, the power supply unit 66 converts the input battery voltage Vb into a lower external power supply voltage Vc and outputs it to the pressure detection device 5 provided outside the control device 6. Furthermore, the grounding end (GND) of the power supply unit 66 is connected to the outside (for example, the cylinder block 2 of the internal combustion engine 1 shown in FIG. 1). Thereby, each part (MCU62 etc.) which comprises the control apparatus 6 operate | moves using the electric potential of the ground terminal (GND) of the power supply part 66 as a reference | standard (ground). Note that the operating voltage output from the power supply unit 66 and the external power supply voltage Vc may have the same magnitude or different magnitudes.
　図１０は、内燃機関１、圧力検出装置５、制御装置６および伝送ケーブル８の、電気的な接続関係を説明するための図である。 FIG. 10 is a diagram for explaining an electrical connection relationship among the internal combustion engine 1, the pressure detection device 5, the control device 6, and the transmission cable 8.
　まず、圧力検出装置５の内部における接続関係について説明を行う。
　圧力検出装置５においては、圧電素子１０の一端が、入力側第１接続ピン２１ａ等を介して実装基板２１０の入力信号端子２１１ａに接続されている。また、圧電素子１０の他端は、ダイアフラムヘッド４０（図１０には図示せず）を介してハウジング３０（より具体的には第１ハウジング３１）に接続されている。また、実装基板２１０に設けられた入力接地端子２１１ｂは、入力側第２接続ピン２１ｂ等を介してハウジング３０（より具体的には第２ハウジング３２）に接続されている。さらに、実装基板２１０に設けられた電源端子２１１ｃは出力側第１接続ピン２１ｃに接続され、実装基板２１０に設けられた出力信号端子２１１ｄは出力側第２接続ピン２１ｄに接続され、実装基板２１０に設けられた出力接地端子２１１ｅは出力側第３接続ピン２１ｅに接続される。 First, the connection relationship inside the pressure detection device 5 will be described.
In the pressure detection device 5, one end of the piezoelectric element 10 is connected to the input signal terminal 211a of the mounting substrate 210 via the input-side first connection pin 21a and the like. The other end of the piezoelectric element 10 is connected to the housing 30 (more specifically, the first housing 31) via a diaphragm head 40 (not shown in FIG. 10). The input ground terminal 211b provided on the mounting substrate 210 is connected to the housing 30 (more specifically, the second housing 32) via the input-side second connection pin 21b and the like. Furthermore, the power supply terminal 211c provided on the mounting board 210 is connected to the output side first connection pin 21c, and the output signal terminal 211d provided on the mounting board 210 is connected to the output side second connection pin 21d. The output ground terminal 211e provided on the output side is connected to the output-side third connection pin 21e.
　次に、内燃機関１の内部における接続関係について説明を行う。
　内燃機関１では、ともに金属で構成されたシリンダブロック２とシリンダヘッド４とが、互いに接触した状態で配置されている（図１参照）。したがって、シリンダブロック２およびシリンダヘッド４は、互いに接続された状態にある。 Next, the connection relationship inside the internal combustion engine 1 will be described.
In the internal combustion engine 1, a cylinder block 2 and a cylinder head 4, both of which are made of metal, are arranged in contact with each other (see FIG. 1). Accordingly, the cylinder block 2 and the cylinder head 4 are connected to each other.
　続いて、伝送ケーブル８を介した、圧力検出装置５と制御装置６との接続関係について説明を行う。
　圧力検出装置５に設けられた出力側第１接続ピン２１ｃは、伝送ケーブル８を構成する第１ケーブル８１の一端に接続され、この第１ケーブル８１の他端は、制御装置６に設けられた電源部６６（図９参照）における外部電源電圧Ｖｃの出力ライン（図中実線矢印で示す）に接続される。また、圧力検出装置５に設けられた出力側第２接続ピン２１ｄは、伝送ケーブル８を構成する第２ケーブル８２の一端に接続され、この第２ケーブル８２の他端は、制御装置６に設けられた入力受付部６１（図９参照）に接続される。さらに、圧力検出装置５に設けられた出力側第３接続ピン２１ｅは、伝送ケーブル８を構成する第３ケーブル８３の一端に接続され、この第３ケーブル８３の他端は、制御装置６に設けられた電源部６６（図９参照）における外部電源電圧Ｖｃの接地ライン（図中破線矢印で示す）に接続される。 Subsequently, the connection relationship between the pressure detection device 5 and the control device 6 via the transmission cable 8 will be described.
The output side first connection pin 21 c provided in the pressure detection device 5 is connected to one end of the first cable 81 constituting the transmission cable 8, and the other end of the first cable 81 is provided in the control device 6. The power supply unit 66 (see FIG. 9) is connected to an output line (indicated by a solid arrow in the figure) of the external power supply voltage Vc. The output-side second connection pin 21 d provided in the pressure detection device 5 is connected to one end of the second cable 82 that constitutes the transmission cable 8, and the other end of the second cable 82 is provided in the control device 6. Connected to the input receiving unit 61 (see FIG. 9). Further, the output-side third connection pin 21 e provided in the pressure detection device 5 is connected to one end of a third cable 83 constituting the transmission cable 8, and the other end of the third cable 83 is provided in the control device 6. Connected to a ground line (indicated by a broken-line arrow in the figure) of external power supply voltage Vc in power supply unit 66 (see FIG. 9).
　さらに、圧力検出装置５と内燃機関１との接続関係について説明を行う。
　圧力検出装置５に設けられたハウジング３０は、内燃機関１に設けられたシリンダヘッド４に対し、上述したようにねじ込みによって取り付けられている。したがって、ともに金属で構成されたハウジング３０とシリンダヘッド４とが接続されていることになる。 Further, the connection relationship between the pressure detection device 5 and the internal combustion engine 1 will be described.
The housing 30 provided in the pressure detection device 5 is attached to the cylinder head 4 provided in the internal combustion engine 1 by screwing as described above. Therefore, the housing 30 and the cylinder head 4 both made of metal are connected.
　さらにまた、制御装置６と内燃機関１との接続関係について説明を行う。
　制御装置６に設けられた電源部６６（図９参照）の接地端は、内燃機関１に設けられたシリンダブロック２に接続される。 Furthermore, the connection relationship between the control device 6 and the internal combustion engine 1 will be described.
A grounding end of a power supply unit 66 (see FIG. 9) provided in the control device 6 is connected to a cylinder block 2 provided in the internal combustion engine 1.
　本実施の形態において、内燃機関１に設けられたシリンダブロック２およびシリンダヘッド４は、上述したように接続関係にある。したがって、圧力検出装置５における圧電素子１０のグランドと、圧力検出装置５における実装基板２１０のグランドと、制御装置６における電源部６６（図９参照）のグランドとは、これらシリンダブロック２およびシリンダヘッド４を介して共通に設定されていることになる。
　また、本実施の形態において、圧力検出装置５における実装基板２１０のグランドと、制御装置６における電源部６６（図９参照）のグランドとは、伝送ケーブル８の第３ケーブル８３を介して共通に設定されている。 In the present embodiment, the cylinder block 2 and the cylinder head 4 provided in the internal combustion engine 1 are connected as described above. Therefore, the ground of the piezoelectric element 10 in the pressure detection device 5, the ground of the mounting substrate 210 in the pressure detection device 5, and the ground of the power supply unit 66 (see FIG. 9) in the control device 6 are the cylinder block 2 and the cylinder head. 4 is set in common through the terminal 4.
Further, in the present embodiment, the ground of the mounting substrate 210 in the pressure detection device 5 and the ground of the power supply unit 66 (see FIG. 9) in the control device 6 are shared via the third cable 83 of the transmission cable 8. Is set.
　ここで、本実施の形態の圧力検出装置５は、単体で販売される場合と、圧力検出装置５に伝送ケーブル８を装着した状態で販売される場合とがあり得る。これらのうち、前者においては、出力側第１接続ピン２１ｃが定電圧供給手段として、出力側第２接続ピン２１ｄが出力信号伝送手段として、出力側第３接続ピン２１ｅが接地手段として、それぞれ機能する。これに対し、後者においては、出力側第１接続ピン２１ｃに接続される第１ケーブル８１が定電圧供給手段として、出力側第２接続ピン２１ｄに接続される第２ケーブル８２が出力信号伝送手段として、出力側第３接続ピン２１ｅに接続される第３ケーブル８３が接地手段として、それぞれ機能する。 Here, the pressure detection device 5 of the present embodiment may be sold alone or sold with the transmission cable 8 attached to the pressure detection device 5. Among these, in the former, the output side first connection pin 21c functions as a constant voltage supply unit, the output side second connection pin 21d functions as an output signal transmission unit, and the output side third connection pin 21e functions as a ground unit. To do. On the other hand, in the latter case, the first cable 81 connected to the output side first connection pin 21c is a constant voltage supply means, and the second cable 82 connected to the output side second connection pin 21d is an output signal transmission means. As described above, the third cables 83 connected to the output-side third connection pins 21e function as grounding means.
　本実施の形態の内燃機関１を搭載した装置では、内燃機関１を始動させる際に、この装置に搭載される各種機器の故障診断が実行される。例えば圧力検出システムにおいては、圧力検出装置５の故障診断に加えて、圧力検出装置５と制御装置６とを接続する伝送ケーブル８（より具体的には、第１ケーブル８１、第２ケーブル８２および第３ケーブル８３）の故障診断（断線検出）が行われる。 In the apparatus equipped with the internal combustion engine 1 of the present embodiment, when the internal combustion engine 1 is started, failure diagnosis of various devices mounted on the apparatus is executed. For example, in the pressure detection system, in addition to the failure diagnosis of the pressure detection device 5, the transmission cable 8 (more specifically, the first cable 81, the second cable 82, and the like) that connects the pressure detection device 5 and the control device 6. Fault diagnosis (disconnection detection) of the third cable 83) is performed.
　図１１は、内燃機関１の始動時における断線検出動作の手順を説明するためのフローチャートである。
　内燃機関１を始動させるためのイグニッションスイッチ（図示せず）がオンに設定されると（ステップ１１）、制御装置６は、電源部６６から伝送ケーブル８を介して圧力検出装置５に外部出力電圧Ｖｏの給電を開始する（ステップ１２）。続いて、制御装置６は、制御装置６と圧力検出装置５とを接続する伝送ケーブル８の断線検出動作を実行し（ステップ１３）、断線が検出されたか否かを判断する（ステップ１４）。 FIG. 11 is a flowchart for explaining the procedure of the disconnection detection operation at the start of the internal combustion engine 1.
When an ignition switch (not shown) for starting the internal combustion engine 1 is set to ON (step 11), the control device 6 sends an external output voltage from the power source 66 to the pressure detection device 5 via the transmission cable 8. Vo power supply is started (step 12). Subsequently, the control device 6 performs a disconnection detection operation of the transmission cable 8 connecting the control device 6 and the pressure detection device 5 (step 13), and determines whether or not a disconnection is detected (step 14).
　ステップ１４において肯定の判断（ＹＥＳ）を行った場合、すなわち、伝送ケーブル８を構成する第１ケーブル８１、第２ケーブル８２および第３ケーブル８３のいずれかにおいて断線が検出された場合、制御装置６は、どのケーブルにおいて断線が検出されたかについてのデータを、制御装置６に内蔵されるＥＥＰＲＯＭ６３に記録する（ステップ１５）。続いて、制御装置６は、図示しないユーザインタフェースに断線が検出されたことに関するメッセージを表示させ（ステップ１６）、一連の処理を完了する。 If an affirmative determination (YES) is made in step 14, that is, if disconnection is detected in any of the first cable 81, the second cable 82, and the third cable 83 that constitute the transmission cable 8, the control device 6 Records data on which cable is detected to be disconnected in the EEPROM 63 built in the control device 6 (step 15). Subsequently, the control device 6 displays a message on the disconnection detection on a user interface (not shown) (step 16), and completes a series of processing.
　一方、ステップ１４において否定の判断（ＮＯ）を行った場合、すなわち、伝送ケーブル８を構成する第１ケーブル８１、第２ケーブル８２および第３ケーブル８３のいずれにおいても断線が検出されなかった場合、制御装置６は、そのまま処理を完了する。 On the other hand, if a negative determination (NO) is made in step 14, that is, if no disconnection is detected in any of the first cable 81, the second cable 82, and the third cable 83 constituting the transmission cable 8, The control device 6 completes the process as it is.
　ここで、本実施の形態では、圧力検出装置５の実装基板２１０に設けられた出力接地端子２１１ｅが、出力側第３接続ピン２１ｅおよび第３ケーブル８３を介して制御装置６の電源部６６に接続されており、この電源部６６の接地端が、シリンダブロック２を介して接地されている。また、圧力検出装置５の実装基板２１０に設けられた入力接地端子２１１ｂが、入力側第２接続ピン２１ｂを介してハウジング３０に接続されており、このハウジング３０は、シリンダヘッド４を介して接地されている。このため、例えば第３ケーブル８３で断線が発生した場合においても、実装基板２１０が、入力接地端子２１１ｂを介して接地されているために、上述した断線検出動作において断線を検出できなくなる懸念がある。 Here, in the present embodiment, the output ground terminal 211e provided on the mounting substrate 210 of the pressure detection device 5 is connected to the power supply unit 66 of the control device 6 via the output-side third connection pin 21e and the third cable 83. The power supply unit 66 is grounded via the cylinder block 2. An input ground terminal 211b provided on the mounting board 210 of the pressure detection device 5 is connected to the housing 30 via the input-side second connection pin 21b. The housing 30 is grounded via the cylinder head 4. Has been. For this reason, for example, even when a disconnection occurs in the third cable 83, there is a concern that the disconnection cannot be detected in the above-described disconnection detection operation because the mounting substrate 210 is grounded via the input ground terminal 211b. .
　これに対し、本実施の形態では、実装基板２１０において、入力接地端子２１１ｂと出力接地端子２１１ｅとの間に直流遮断回路２１５を設け、入力接地端子２１１ｂからハウジング３０に向けて直流電流が流れないようにした。このため、実装基板２１０に直流を供給する場合においては、出力接地端子２１１ｅは接地としての機能を有する一方、入力接地端子２１１ｂは接地としての機能を有さないようになる。その結果、上述した断線検出動作において、断線検出用の信号として直流信号を供給することにより、第３ケーブル８３における断線の有無を検出することが可能となる。 On the other hand, in the present embodiment, in the mounting substrate 210, a DC cutoff circuit 215 is provided between the input ground terminal 211b and the output ground terminal 211e so that no DC current flows from the input ground terminal 211b toward the housing 30. I did it. Therefore, when direct current is supplied to the mounting board 210, the output ground terminal 211e has a function as ground, while the input ground terminal 211b does not have a function as ground. As a result, in the above-described disconnection detection operation, it is possible to detect the presence or absence of disconnection in the third cable 83 by supplying a DC signal as a signal for detecting disconnection.
　次に、本実施の形態の圧力検出装置５による圧力検出動作について説明する。
　内燃機関１の作動時には、センサ部１００のダイアフラムヘッド４０の内側部４２に、燃焼室Ｃ内で発生した燃焼圧が付与される。そして、ダイアフラムヘッド４０に付与された燃焼圧が、第１電極部５０と第２電極部５５とによって挟まれた圧電素子１０に作用することにより、この圧電素子１０に燃焼圧に応じた電荷が生じる。圧電素子１０に生じた電荷は、第２電極部５５、コイルスプリング７０および伝導部材２２を介して、入力電荷Ｑｉとして回路基板部２１の実装基板２１０に供給される。実装基板２１０に供給された入力電荷Ｑｉは、実装基板２１０に設けられた各種回路にて積分処理および増幅処理がなされた後、その電荷に応じた外部出力電圧Ｖｏが、回路基板部２１から伝送ケーブル８を介して、制御装置６に供給される。 Next, the pressure detection operation by the pressure detection device 5 of the present embodiment will be described.
During operation of the internal combustion engine 1, the combustion pressure generated in the combustion chamber C is applied to the inner portion 42 of the diaphragm head 40 of the sensor unit 100. The combustion pressure applied to the diaphragm head 40 acts on the piezoelectric element 10 sandwiched between the first electrode portion 50 and the second electrode portion 55, so that electric charges corresponding to the combustion pressure are applied to the piezoelectric element 10. Arise. The electric charge generated in the piezoelectric element 10 is supplied to the mounting board 210 of the circuit board part 21 as the input electric charge Qi through the second electrode part 55, the coil spring 70 and the conductive member 22. The input charge Qi supplied to the mounting board 210 is subjected to integration processing and amplification processing in various circuits provided on the mounting board 210, and then an external output voltage Vo corresponding to the charge is transmitted from the circuit board portion 21. It is supplied to the control device 6 via the cable 8.
　ここで、本実施の形態の圧力検出装置５は、内燃機関１に取り付けられており、内燃機関１の動作に伴って発生する電磁波が、圧力検出装置５に設けられた実装基板２１０に影響を与える。すなわち、実装基板２１０で用いられる各種信号および実装基板２１０から出力される外部出力電圧Ｖｏに、上述した電磁波に起因するノイズが重畳されてしまう懸念がある。 Here, the pressure detection device 5 of the present embodiment is attached to the internal combustion engine 1, and electromagnetic waves generated in accordance with the operation of the internal combustion engine 1 affect the mounting substrate 210 provided in the pressure detection device 5. give. That is, there is a concern that noise due to the above-described electromagnetic waves is superimposed on various signals used on the mounting substrate 210 and the external output voltage Vo output from the mounting substrate 210.
　これに対し、本実施の形態では、実装基板２１０において、直流遮断回路２１５を介して入力接地端子２１１ｂを設けているので、各回路で生じた交流成分のノイズについては、直流遮断回路２１５を通過させて接地に落とすことができる。このため、圧力検出装置５から制御装置６に伝送される外部出力電圧Ｖｏに重畳されるノイズを低減することができる。 On the other hand, in the present embodiment, the input ground terminal 211b is provided on the mounting substrate 210 via the DC cutoff circuit 215. Therefore, AC component noise generated in each circuit passes through the DC cutoff circuit 215. Can be dropped to ground. For this reason, the noise superimposed on the external output voltage Vo transmitted from the pressure detection device 5 to the control device 6 can be reduced.
　なお、本実施の形態では、圧電素子１０を用いた圧力検出装置５と制御装置６とを接続する伝送ケーブル８の断線検出を例として説明を行ったが、これに限られるものではなく、例えば温度、湿度、あるいは流量など、各種物理量を検出する検出装置と制御装置６とを接続する伝送ケーブル８の断線検出にも適用することができる。 In the present embodiment, the disconnection detection of the transmission cable 8 that connects the pressure detection device 5 and the control device 6 using the piezoelectric element 10 has been described as an example. However, the present invention is not limited to this. The present invention can also be applied to detection of disconnection of the transmission cable 8 that connects the control device 6 and a detection device that detects various physical quantities such as temperature, humidity, or flow rate.
　また、本実施の形態では、直流遮断回路２１５としてコンデンサを用いていたが、これに限られるものではなく、例えば入力接地端子２１１ｂ側をアノードとするダイオードを用いてもよい。 In this embodiment, a capacitor is used as the DC cutoff circuit 215. However, the present invention is not limited to this. For example, a diode having an anode on the input ground terminal 211b side may be used.
　さらに、本実施の形態では、実装基板２１０に直流遮断回路２１５を組み込んでいたが、これに限られるものではなく、例えば実装基板２１０とハウジング３０との間に、別途、直流遮断回路２１５を設けてもかまわない。 Further, in the present embodiment, the DC cut-off circuit 215 is incorporated in the mounting board 210. However, the present invention is not limited to this. For example, a DC cut-off circuit 215 is separately provided between the mounting board 210 and the housing 30. It doesn't matter.
１…内燃機関、２…シリンダブロック、３…ピストン、４…シリンダヘッド、５…圧力検出装置、６…制御装置、８…伝送ケーブル、１０…圧電素子、２１…回路基板部、２２…伝導部材、２３…覆い部材、３０…ハウジング、６１…入力受付部、６２…ＭＣＵ（Micro Control Unit）、６３…ＥＥＰＲＯＭ、６４…駆動信号出力部、６６…電源部、６７…通信部、８０…コネクタ、８１…第１ケーブル、８２…第２ケーブル、８３…第３ケーブル、１００…センサ部、２００…信号処理部、２１０…実装基板、２１１…プリント配線基板、２１２…保護回路、２１３…積分回路、２１４…増幅回路、２１５…直流遮断回路、２１６…電源回路、３００…保持部材 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Cylinder block, 3 ... Piston, 4 ... Cylinder head, 5 ... Pressure detection apparatus, 6 ... Control apparatus, 8 ... Transmission cable, 10 ... Piezoelectric element, 21 ... Circuit board part, 22 ... Conductive member 23 ... Cover member, 30 ... Housing, 61 ... Input receiving unit, 62 ... Micro control unit (MCU), 63 ... EEPROM, 64 ... Drive signal output unit, 66 ... Power supply unit, 67 ... Communication unit, 80 ... Connector, 81 ... 1st cable, 82 ... 2nd cable, 83 ... 3rd cable, 100 ... Sensor part, 200 ... Signal processing part, 210 ... Mounting board, 211 ... Printed wiring board, 212 ... Protection circuit, 213 ... Integration circuit, 214 ... Amplifying circuit, 215 ... DC cut-off circuit, 216 ... Power supply circuit, 300 ... Holding member

Claims (5)

  1. 　物理量の変化を検出する検出素子と、当該検出素子から出力される検出信号に処理を施す信号処理回路と、当該検出素子および当該信号処理回路が取り付けられるとともに、接地体に電気的に接続される筐体と、当該筐体と当該信号処理回路におけるグランドとを、直流電流の通電を抑制しながら接続する直流抑制部とを含む検出部と、
    　前記検出部における前記信号処理回路に定電圧を供給するための定電圧供給線と、当該信号処理部から出力される出力信号を伝送するための出力信号伝送線と、当該信号処理回路における前記グランドに接続するための接地線とを介して当該検出部に接続され、さらに、前記接地体に電気的に接続されることで、当該検出部に当該定電圧を供給するとともに当該検出部から入力される当該出力信号に処理を施す供給／処理部とを含む検出システム。     A detection element for detecting a change in physical quantity, a signal processing circuit for processing a detection signal output from the detection element, the detection element and the signal processing circuit are attached, and are electrically connected to a grounding body A detection unit including a casing, and a DC suppression unit that connects the casing and the ground in the signal processing circuit while suppressing energization of a DC current;
    A constant voltage supply line for supplying a constant voltage to the signal processing circuit in the detection unit, an output signal transmission line for transmitting an output signal output from the signal processing unit, and the ground in the signal processing circuit Is connected to the detection unit via a ground line for connection to the power source, and is further electrically connected to the grounding body so that the constant voltage is supplied to the detection unit and input from the detection unit. And a supply / processing unit that processes the output signal.
  2. 　前記検出素子は、圧電体を用いて圧力を検出する圧電素子で構成され、
    　前記信号処理回路は、前記圧電素子から入力される電荷信号を積分することで、当該電荷信号を電圧信号に変換する積分回路と、当該積分回路から入力される当該電圧信号を増幅し、得られた増幅信号を、前記出力信号伝送線を介して前記供給／処理部に出力する増幅回路とを有することを特徴とする請求項１記載の検出システム。     The detection element includes a piezoelectric element that detects pressure using a piezoelectric body,
    The signal processing circuit is obtained by integrating the charge signal input from the piezoelectric element to amplify the voltage signal input from the integration circuit that converts the charge signal into a voltage signal and the integration circuit. The detection system according to claim 1, further comprising: an amplification circuit that outputs the amplified signal to the supply / processing unit via the output signal transmission line.
  3. 　前記信号処理回路は、前記定電圧供給線を介して入力される前記定電圧を、当該定電圧よりも低い電圧に変換して、前記積分回路および前記増幅回路に供給する電源回路をさらに備えることを特徴とする請求項２記載の検出システム。 The signal processing circuit further includes a power supply circuit that converts the constant voltage input via the constant voltage supply line into a voltage lower than the constant voltage and supplies the converted voltage to the integrating circuit and the amplifier circuit. The detection system according to claim 2.
  4. 　前記直流抑制部は、コンデンサを含むことを特徴とする請求項１乃至３のいずれか１項記載の検出システム。 The detection system according to any one of claims 1 to 3, wherein the direct current suppression unit includes a capacitor.
  5. 　物理量の変化を検出する検出素子と、
    　前記検出素子から出力される検出信号に処理を施す信号処理回路と、
    　前記検出素子および前記信号処理回路が取り付けられる筐体と、
    　前記信号処理回路に定電圧を供給するための定電圧供給手段と、
    　前記信号処理回路から出力される出力信号を伝送するための出力信号伝送手段と、
    　前記信号処理回路におけるグランドに接続するための接地手段と、
    　前記筐体と前記信号処理回路における前記グランドとを、直流電流の通電を抑制しながら接続する直流抑制部と
    を含む検出装置。     A detecting element for detecting a change in physical quantity;
    A signal processing circuit for processing a detection signal output from the detection element;
    A housing to which the detection element and the signal processing circuit are attached;
    Constant voltage supply means for supplying a constant voltage to the signal processing circuit;
    Output signal transmission means for transmitting an output signal output from the signal processing circuit;
    Grounding means for connecting to ground in the signal processing circuit;
    A detection apparatus comprising: a DC suppression unit that connects the casing and the ground in the signal processing circuit while suppressing energization of DC current.
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