WO2020111132A1 - Liquid-level detection device - Google Patents

Liquid-level detection device Download PDF

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Publication number
WO2020111132A1
WO2020111132A1 PCT/JP2019/046402 JP2019046402W WO2020111132A1 WO 2020111132 A1 WO2020111132 A1 WO 2020111132A1 JP 2019046402 W JP2019046402 W JP 2019046402W WO 2020111132 A1 WO2020111132 A1 WO 2020111132A1
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Prior art keywords
case
ultrasonic
liquid level
connecting member
extension pipe
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PCT/JP2019/046402
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French (fr)
Japanese (ja)
Inventor
国臣 赤塚
宮川　功
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株式会社デンソー
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Publication of WO2020111132A1 publication Critical patent/WO2020111132A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/296—Acoustic waves

Definitions

  • the present disclosure relates to a liquid level detection device.
  • liquid level detection device that detects the position of the liquid level by transmitting ultrasonic waves with an ultrasonic oscillating element and receiving the reflected waves reflected by the liquid level at the bottom of the tank that stores the liquid.
  • Patent Document 1 describes that such a liquid level detection device is used for the purpose of detecting the fuel liquid level in a fuel tank equipped in an automobile.
  • Patent Document 1 as a liquid level detection device, a case accommodating an ultrasonic oscillating element, and a propagation path of ultrasonic waves transmitted from the ultrasonic oscillating element in the internal space are attached to one end side of the case. What has a cylindrical transmission pipe to form is described.
  • a lead wire for applying a voltage to the ultrasonic oscillating element is connected to the ultrasonic oscillating element, and the lead wire extends in the direction opposite to the extending direction of the transmission pipe and extends out of the case. ing.
  • the lead wire as a connecting member electrically connected to the ultrasonic oscillator is sufficiently electrically. It has been found that the signal is not shielded and may have noise in the detection signal. Specific sources of noise include a motor that drives a pump for supplying fuel in a tank to an engine, and electronic/electrical devices existing around a vehicle, such as a road heater embedded in a road. Is mentioned.
  • One aspect of the present disclosure provides a liquid level detection device in which noise on a detection signal is reduced.
  • the ultrasonic oscillator can transmit and receive ultrasonic waves.
  • the case is a case forming an accommodation chamber for accommodating the ultrasonic oscillating element, and a bottom portion provided on the surface side of the ultrasonic oscillating element for transmitting and receiving ultrasonic waves and a surface for transmitting and receiving ultrasonic waves of the ultrasonic oscillating element. It has a lid part provided on the surface side opposite to the above, and an outer peripheral part provided between the bottom part and the lid part and defining a storage chamber together with the bottom part and the lid part.
  • the metal tube forms an ultrasonic wave propagation path extending from the bottom of the case.
  • the connecting member is electrically connected to the ultrasonic oscillating element, is attached to the ultrasonic oscillating element, and extends toward the lid portion of the case.
  • the metal tube has an extension tube portion extended from a portion of the metal tube that forms a propagation path. At least a portion of the connecting member resides within the extension tube section.
  • At least a part of the connecting member electrically connected to the ultrasonic wave oscillating element is electrically shielded by the extension tube portion of the metal tube, so that noise on the detection signal can be reduced.
  • the liquid level detection device 100 shown in FIG. 1 is mounted on a vehicle and transmits ultrasonic waves at the bottom of a tank 200 that stores liquid fuel, and receives reflected waves reflected by the liquid level to obtain the liquid level. It is a device for detecting the position of. It should be noted that a part of the liquid level detection device 100 shown in FIG. 1 is shown not on a cross section but on a side face in order to make the internal structure easy to understand.
  • the liquid level detection device 100 is roughly provided with two functional parts, specifically, a sensor part 1 and a housing part 2 from a functional point of view.
  • the sensor unit 1 is an assembly that functions as an ultrasonic transmitting/receiving unit as a whole. As shown in FIG. 2, the sensor unit 1 includes an ultrasonic oscillator 11, a connecting member 13, an elastic body 14, a case 15, and an external connecting terminal 17.
  • the ultrasonic oscillator 11 is an element that transmits and receives ultrasonic waves.
  • the ultrasonic oscillating element 11 is made of a material having a piezoelectric effect, such as PZT, and has a disk shape.
  • the piezo effect is a characteristic in which a volume changes when a voltage is applied, and a voltage is generated when an external force is applied.
  • Electrodes printed on substantially the entire surface are provided on both surfaces of the ultrasonic oscillator 11. When a voltage is applied from an external electric circuit between the electrodes on both sides via the lead wire 3 shown in FIG. Ultrasonic waves are generated by vibrating.
  • the elastic body 14 is a substantially cylindrical member arranged coaxially with the central axis A of the ultrasonic oscillator 11. Of the two end surfaces on both sides in the axial direction, the first surface is in contact with the ultrasonic oscillator 11 and the second surface is in contact with the lid portion 152 of the case 15 which will be described later.
  • the elastic body 14 is formed of an elastic material such as soft resin or rubber.
  • the case 15 forms a housing chamber 16 for housing the ultrasonic oscillator 11 and the elastic body 14.
  • the case 15 has a bottom portion 151, a lid portion 152, and an outer peripheral portion 153.
  • the bottom portion 151 is provided on the surface 111 (hereinafter, referred to as “front surface 111”) side of the ultrasonic oscillator 11 that transmits and receives ultrasonic waves.
  • the lid portion 152 is provided on the surface 112 (hereinafter, referred to as “rear surface 112”) opposite to the surface 111 of the ultrasonic oscillator 11 that transmits and receives ultrasonic waves.
  • the outer peripheral portion 153 is provided between the bottom portion 151 and the lid portion 152, and defines the storage chamber 16 together with the bottom portion 151 and the lid portion 152.
  • the bottom portion 151 and the outer peripheral portion 153 are integrally formed in a bottomed cylindrical shape, and the lid portion 152 is a separate body from these.
  • the lid portion 152 is fixed to the outer peripheral portion 153 by the holes or grooves provided in the lid portion 152 being caught by the claws provided on the outer peripheral portion 153.
  • the dimension in the direction of the central axis A so that the elastic body 14 is housed in the housing chamber 16 of the case 15 while being compressed and elastically deformed by the lid 152 when the lid 152 is fixed to the outer peripheral portion 153. Is designed to be large. Therefore, the ultrasonic oscillator 11 is fixed in a state of being pressed against the bottom surface of the case 15 by the elastic force of the elastic body 14.
  • connection member 13 is a terminal that is attached to the ultrasonic oscillator 11 and electrically connects the ultrasonic oscillator 11 and the external connection terminal 17.
  • the connection member 13 is formed of a metal plate.
  • the liquid level detection device 100 of this embodiment includes a first connecting member 131 and a second connecting member 132 as the connecting member 13.
  • the first connecting member 131 and the second connecting member 132 are provided at positions facing each other with the elastic body 14 interposed therebetween.
  • the first connection member 131 is provided on the front side
  • the second connection member 132 is provided on the back side.
  • one end of the first connection member 131 serves as a holding portion 131a that holds the front surface 111 and the back surface 112 of the ultrasonic oscillator 11 between them.
  • the insulator 12 is interposed between the back surface 112 of the ultrasonic oscillation element 11 and the sandwiching portion 131a, and the sandwiching portion 131a does not directly contact the back surface 112 of the ultrasonic oscillation element 11.
  • the insulator 12 is also interposed between the back surface 111 of the ultrasonic oscillation element 11 and the sandwiching portion 132a of the second connecting member 132, and the sandwiching portion 132a directly contacts the back surface 112 of the ultrasonic oscillation element 11. Not in contact.
  • the insulator 12 is made of an insulating material such as a resin material or a ceramic material.
  • the first connecting member 131 is a ground-side terminal. That is, the first connecting member 131 is grounded.
  • first connecting member 131 and the second connecting member 132 have the same configuration, only the first connecting member 131 will be described below.
  • the first connecting member 131 extends from the ultrasonic oscillator 11 toward the lid 152. Specifically, the first connecting member 131 extends in the direction along the central axis A.
  • the first connecting member 131 is provided between the elastic body 14 and the outer peripheral portion 153 of the case 15, and extends along the inner surface of the outer peripheral portion 153 of the case 15.
  • An end portion of the first connection member 131 on the opposite side to the sandwiching portion 131 a passes through the hole 18 provided in the lid portion 152 and projects to the outside of the accommodation chamber 16. Further, the end portion of the first connection member 131 protruding outside the accommodation chamber 16 is connected to the external connection terminal 17. As shown in FIG.
  • the end portion connected to the external connection terminal 17 and the sandwiching portion 131a have a wavy curved structure in the direction along the central axis A. ing. This is because when the first connecting member 131 is attached to the ultrasonic oscillator 11, the external force applied to the first connecting member 131 is absorbed so that the holding portion 131a does not shift the position where the ultrasonic oscillator 11 is sandwiched. This is because.
  • the case 15 is made of resin.
  • the case 15 is made of metal, for example, the first connecting member 131 is provided along the inner surface of the outer peripheral portion 153 of the case 15, and thus there is a possibility of a short circuit.
  • the case 15 is made of metal, the ultrasonic wave transmitted from the ultrasonic oscillator 11 may be reflected by the bottom 151 of the case 15.
  • the case 15 is made of an insulating resin material.
  • the housing part 2 is an assembly that functions as an ultrasonic wave propagation path as a whole. As shown in FIG. 1, the housing part 2 includes a body 21, a first metal tube 22, a second metal tube 23, and a reflector 24.
  • the body 21 is a resin member that holds and fixes the sensor unit 1, the first metal tube 22, the second metal tube 23, and the reflection plate 24.
  • the first metal tube 22, the second metal tube 23, and the reflector 24 are attached to the body 21.
  • the body 21 is fixed to the bottom surface of the tank 200.
  • the sensor unit 1 is attached to the body 21 so that the central axis A of the ultrasonic oscillator 11 is coaxial with the central axis A of the first metal tube 22.
  • the first metal tube 22 is a metal tube.
  • the first metal tube 22 is made of stainless steel.
  • the first metal pipe 22 has a propagation pipe portion 221 and an extension pipe portion 222.
  • the propagation tube portion 221 is a substantially frustoconical tube.
  • the cross section of the propagation tube portion 221 in a plane orthogonal to the central axis A is circular.
  • the propagation pipe portion 221 forms a first propagation path 4 which is a propagation path of ultrasonic waves and extends from the bottom portion 151 of the case 15.
  • the first propagation path 4 extends from the bottom portion 151 of the case 15 along the central axis A toward the side opposite to the lid portion 152 of the case 15.
  • the first propagation path 4 has a conical portion 41, a linear portion 42, and a step portion 43.
  • the conical portion 41 is a truncated cone-shaped portion whose cross-sectional area gradually decreases with distance from the ultrasonic oscillator 11. In other words, the diameter of the cross section of the conical portion 41 in the plane orthogonal to the central axis A decreases as the distance from the ultrasonic oscillation element 11 increases.
  • the straight portion 42 has a constant cross-sectional area, that is, a straight tubular portion.
  • the step portion 43 is a portion that connects the conical portion 41 and the linear portion 42, and the cross-sectional area is reduced stepwise at the end portion of the conical portion 41 opposite to the end portion where the ultrasonic oscillator 11 is provided. It is a part. Due to the presence of the step portion 43, an annular reference surface 223 is formed in the first metal pipe 22.
  • the extension pipe part 222 is a part of the first metal pipe 22 extended from the propagation pipe part 221.
  • the extension pipe part 222 is specifically extended from the propagation pipe part 221 so that at least a part of the first connection member 131 and the second connection member 132 is present in the extension pipe part 222.
  • the extension pipe portion 222 extends from the propagation pipe portion 221 along the central axis A toward the lid portion 152 of the case 15.
  • the extension pipe portion 222 extends from the propagation pipe portion 221 to the end 161 on the lid portion 152 side of the accommodation chamber 16 and in the thickness direction of the lid portion 152, that is, It extends part way in the direction along the central axis A.
  • the extension tube portion 222 covers the outer side of the outer peripheral portion 153 of the case 15. In the present embodiment, the extension pipe portion 222 covers the entire circumference of the outer peripheral portion 153 of the case 15.
  • the second metal tube 23 is a straight metal tube.
  • the second metal tube 23 is made of stainless steel.
  • the center axis B of the second metal tube 23 is orthogonal to the center axis A, and the second metal tube 23 is continuous with the end of the first metal tube 22 on the side of the straight portion 42 via the body 21. Is provided.
  • the second metal tube 23 has a circular cross section in a plane orthogonal to the central axis B.
  • the upper end portion of the second metal pipe 23 is located so as to project upward by a predetermined length from the liquid level when the amount of fuel stored in the tank 200 is maximum.
  • the second metal tube 23 forms the second propagation path 5 which is a part of the propagation path of ultrasonic waves.
  • the second propagation path 5 extends from the bottom of the tank 200 toward the liquid surface. Specifically, the second propagation path 5 extends vertically from the bottom of the tank 200.
  • the diameter of the second propagation path 5 in this embodiment is equal to the diameter of the straight portion 42.
  • the reflector 24 is a metal plate. When the reflector 24 is held and fixed to the body 21, the central axis A of the first metal tube 22 and the central axis B of the second metal tube 23 intersect at the reflecting surface 241 of the reflector 24. It is arranged to.
  • the reflection plate 24 reflects the ultrasonic waves transmitted from the ultrasonic oscillator 11 toward the liquid surface of the fuel. Specifically, the reflector 24 directs the ultrasonic waves traveling along the central axis A of the first metal tube 22 in the direction in which the incident angle to the liquid surface is 0°, that is, in the direction orthogonal to the liquid surface. It is installed so that it reflects. In this embodiment, the reflection plate 24 is provided so as to be inclined at 45° with respect to the liquid surface.
  • the first connecting member 131 which is the ground side terminal, and the extension tube portion 222 are electrically connected.
  • the first connecting member 131 and the extension pipe portion 222 are electrically connected by the member 19 passing through the through hole 154 provided in the outer peripheral portion 153 of the case 15.
  • the member 19 is a lead wire.
  • the member 19 is not shown in FIG. 2, and the insulator 12 is not shown in FIG.
  • the extension pipe portion 222 extends from the propagation pipe portion 221 to at least the end 161 of the housing 15 on the lid portion 152 side of the case 15. That is, most of the first connecting member 131 and the second connecting member 132 are covered with the extension pipe portion 222. Therefore, the first connecting member 131 and the second connecting member 132 are electrically shielded more effectively by the extension pipe portion 222.
  • the first connecting member 131 is grounded, and the first connecting member 131 and the extension pipe portion 222 are electrically connected. Since the extension pipe part 222 is electrically connected to the ground, the first connection member 131 and the second connection member 132 are electrically shielded by the extension pipe part 222 more effectively. Further, since the extension pipe part 222 is connected to the first connection member 131 which is already grounded, it is not necessary to newly provide a wiring for grounding the extension pipe part 222, for example.
  • the shape of the extension pipe portion 222 is not limited to the shape shown in the above embodiment.
  • the extension pipe part 222 covers the entire circumference of the outer peripheral part 153 of the case 15, but the extension pipe part 222 does not necessarily have to cover the entire circumference of the outer peripheral part 153.
  • the extension pipe portion 222 may partially cover the entire circumference of the outer peripheral portion 153.
  • the extension tube portion 222 may be formed of punching metal or may have a mesh shape. In such a case, the ratio of the portion covered by the extension pipe portion 222 to the entire circumference of the outer peripheral portion 153 depends on the position of the noise generation source or the like so that the intensity of generated noise is equal to or less than a desired value. It can be set as appropriate.
  • the ratio of being covered by the extension pipe portion 222 in the entire circumference of the outer peripheral portion 153 is large. Therefore, it is preferable that the extension pipe portion 222 covers the entire circumference of the outer peripheral portion 153.
  • the end portion of the extension pipe portion 222 has a shape obtained by cutting a circular pipe along a plane perpendicular to the central axis A, but the shape of the end portion of the extension pipe portion 222 is not limited to this.
  • the end portion of the extension pipe portion 222 may have a shape obtained by cutting a circular pipe along a surface inclined with respect to the central axis A.
  • the shape of the end portion of the extension tube portion 222 is appropriately set in accordance with the arrangement of other members constituting the sensor portion 1, the position of the noise generation source, etc. within a range in which the intensity of generated noise is less than or equal to a desired value. be able to.
  • the member 19 that electrically connects the first connection member 131 and the extension tube portion 222 is a lead wire, but the member 19 is not limited to this.
  • a terminal may be used as the member 19 instead of the lead wire.
  • a part of the first connecting member 131 may be the member 19.
  • extension pipe part 222 is grounded via the first connecting member 131, but the extension pipe part 222 may be grounded not via the first connecting member 131.
  • the first connection member 131 and the extension pipe portion 222 are electrically connected by the member 19 that passes through the through hole 154 provided in the outer peripheral portion 153 of the case 15.
  • the method of connecting the first connecting member 131 and the extension pipe portion 222 is not limited to this.
  • a part of the extension pipe part 222 may be extended until it penetrates through the lid part 152 to project, and the projecting part and the external connection terminal 17 connected to the ground may be connected.
  • the first connecting member 131 and the extension pipe portion 222 may be connected by a member that passes between the outer peripheral portion 153 and the lid portion 152.
  • the first metal pipe 22 and the second metal pipe 23 are made of stainless steel, but the metal forming the first metal pipe 22 and the second metal pipe 23 is not limited to this. Not done.
  • the metal include iron, aluminum, and those obtained by subjecting these to plating treatment such as Ni plating and Zn plating.
  • the case 15 is made of an insulating resin material, but the material of the case 15 is not limited to this.
  • the case 15 may be made of a conductive resin material.
  • the function of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other above embodiment.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

A liquid-level detection device (100) is provided with an ultrasonic oscillating element (11), a case (15), a metal tube (22), and a connecting member (13). The case forms an accommodating chamber (16) for accommodating the ultrasonic oscillating element. The metal tube forms a propagation route (4) for ultrasonic waves, the propagation route extending from a bottom part (151) of the case. The connecting member is electrically connected to the ultrasonic oscillating element, is attached to the ultrasonic oscillating element, and extends toward a cover part (152) of the case. The metal tube has an extension tube part (222) extending from a portion (221) of the metal tube that forms the propagation route. At least a portion of the connecting member is present inside the extension tube part.

Description

液面検出装置Liquid level detector 関連出願の相互参照Cross-reference of related applications
　本国際出願は、２０１８年１１月２８日に日本国特許庁に出願された日本国特許出願第２０１８－２２２４７８号に基づく優先権を主張するものであり、日本国特許出願第２０１８－２２２４７８号の全内容を本国際出願に参照により援用する。 This international application claims priority based on Japanese Patent Application No. 2018-222478, filed with the Japan Patent Office on November 28, 2018, and is the same as Japanese Patent Application No. 2018-222478. The entire contents of this International Application are incorporated by reference.
　本開示は、液面検出装置に関する。 The present disclosure relates to a liquid level detection device.
　液体を貯蔵するタンク内の底部において、超音波発振素子によって超音波を送信し、液面で反射した反射波を受信することにより、液面の位置を検出する液面検出装置がある。特許文献１には、このような液面検出装置が自動車に装備される燃料タンク内の燃料液面を検出する用途に用いられることが記載されている。 There is a liquid level detection device that detects the position of the liquid level by transmitting ultrasonic waves with an ultrasonic oscillating element and receiving the reflected waves reflected by the liquid level at the bottom of the tank that stores the liquid. Patent Document 1 describes that such a liquid level detection device is used for the purpose of detecting the fuel liquid level in a fuel tank equipped in an automobile.
　また、特許文献１には、液面検出装置として、超音波発振素子を収納するケースと、ケースの一端側に取り付けられるとともに、内部空間が超音波発振素子から送信された超音波の伝播経路を形成する筒状の伝送管とを備えるものが記載されている。この液面検出装置においては、超音波発振素子に電圧を印加するためのリード線が超音波発振素子に接続され、リード線は伝送管の延びる方向と反対側に延び、ケース外へ延出されている。 Further, in Patent Document 1, as a liquid level detection device, a case accommodating an ultrasonic oscillating element, and a propagation path of ultrasonic waves transmitted from the ultrasonic oscillating element in the internal space are attached to one end side of the case. What has a cylindrical transmission pipe to form is described. In this liquid level detection device, a lead wire for applying a voltage to the ultrasonic oscillating element is connected to the ultrasonic oscillating element, and the lead wire extends in the direction opposite to the extending direction of the transmission pipe and extends out of the case. ing.
特開２００６－１１９０４６号公報JP 2006-119046 A
　しかしながら、本発明者らの詳細な検討の結果、特許文献１に記載されている液面検出装置においては、超音波発振素子に電気的に接続する接続部材としてのリード線が十分に電気的にシールドされておらず、検出信号にノイズがのる場合があることが判明した。ノイズの発生源としては、具体的には、タンク内の燃料をエンジンに供給するためのポンプを駆動するモータ、及び自動車の周囲に存在する電子・電気機器、例えば道路に埋め込まれたロードヒータなどが挙げられる。 However, as a result of a detailed study by the present inventors, in the liquid level detection device described in Patent Document 1, the lead wire as a connecting member electrically connected to the ultrasonic oscillator is sufficiently electrically. It has been found that the signal is not shielded and may have noise in the detection signal. Specific sources of noise include a motor that drives a pump for supplying fuel in a tank to an engine, and electronic/electrical devices existing around a vehicle, such as a road heater embedded in a road. Is mentioned.
　本開示の一局面は、検出信号にのるノイズが低減された液面検出装置を提供する。 One aspect of the present disclosure provides a liquid level detection device in which noise on a detection signal is reduced.
　本開示の一態様は、液面の位置を検出する液面検出装置であって、超音波発振素子と、ケースと、金属管と、接続部材と、を備える。超音波発振素子は、超音波を送受信可能である。ケースは、超音波発振素子を収容する収容室を形成するケースであって、超音波発振素子の超音波を送受信する面側に設けられた底部と、超音波発振素子の超音波を送受信する面と反対の面側に設けられた蓋部と、底部と蓋部との間に設けられ、底部と蓋部とともに収容室を画定する外周部と、を有する。金属管は、超音波の伝播経路であってケースの底部から延びる伝播経路を形成する。接続部材は、超音波発振素子と電気的に接続し、超音波発振素子に取り付けられ、ケースの蓋部に向かって延びる。金属管は、金属管における伝播経路を形成する部分から延長された延長管部を有する。接続部材の少なくとも一部が延長管部内に存在する。 One aspect of the present disclosure is a liquid level detection device that detects a position of a liquid level, and includes an ultrasonic wave oscillating element, a case, a metal tube, and a connecting member. The ultrasonic oscillator can transmit and receive ultrasonic waves. The case is a case forming an accommodation chamber for accommodating the ultrasonic oscillating element, and a bottom portion provided on the surface side of the ultrasonic oscillating element for transmitting and receiving ultrasonic waves and a surface for transmitting and receiving ultrasonic waves of the ultrasonic oscillating element. It has a lid part provided on the surface side opposite to the above, and an outer peripheral part provided between the bottom part and the lid part and defining a storage chamber together with the bottom part and the lid part. The metal tube forms an ultrasonic wave propagation path extending from the bottom of the case. The connecting member is electrically connected to the ultrasonic oscillating element, is attached to the ultrasonic oscillating element, and extends toward the lid portion of the case. The metal tube has an extension tube portion extended from a portion of the metal tube that forms a propagation path. At least a portion of the connecting member resides within the extension tube section.
　このような構成によれば、超音波発振素子と電気的に接続する接続部材の少なくとも一部が金属管の延長管部によって電気的にシールドされるため、検出信号にのるノイズを低減することができる。 According to such a configuration, at least a part of the connecting member electrically connected to the ultrasonic wave oscillating element is electrically shielded by the extension tube portion of the metal tube, so that noise on the detection signal can be reduced. You can
液面検出装置の断面図である。It is sectional drawing of a liquid level detection apparatus. センサ部の水平断面図である。It is a horizontal sectional view of a sensor part. センサ部の垂直断面図である。It is a vertical sectional view of a sensor part.
　以下、本開示の例示的な実施形態について図面を参照しながら説明する。 Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.
　［１．構成］
　図１に示す液面検出装置１００は、車両に搭載され、液体の燃料を貯蔵するタンク２００内の底部において、超音波を送信し、液面で反射した反射波を受信することにより、液面の位置を検出する装置である。なお、図１に示す液面検出装置１００の一部については、内部構造を分かりやすく示すため、断面ではなく側面を示している。液面検出装置１００は、機能的な見地から見て、大きく２つの機能部、具体的には、センサ部１と、ハウジング部２と、を備える。 [1. Constitution]
The liquid level detection device 100 shown in FIG. 1 is mounted on a vehicle and transmits ultrasonic waves at the bottom of a tank 200 that stores liquid fuel, and receives reflected waves reflected by the liquid level to obtain the liquid level. It is a device for detecting the position of. It should be noted that a part of the liquid level detection device 100 shown in FIG. 1 is shown not on a cross section but on a side face in order to make the internal structure easy to understand. The liquid level detection device 100 is roughly provided with two functional parts, specifically, a sensor part 1 and a housing part 2 from a functional point of view.
　センサ部１は、全体として超音波の送受信部として機能するアセンブリである。図２に示すように、センサ部１は、超音波発振素子１１と、接続部材１３と、弾性体１４と、ケース１５と、外部接続端子１７とを備える。 The sensor unit 1 is an assembly that functions as an ultrasonic transmitting/receiving unit as a whole. As shown in FIG. 2, the sensor unit 1 includes an ultrasonic oscillator 11, a connecting member 13, an elastic body 14, a case 15, and an external connecting terminal 17.
　超音波発振素子１１は、超音波を送受信する素子である。超音波発振素子１１は、ＰＺＴなどのピエゾ効果を有する物質によって、円盤状に構成されている。ピエゾ効果とは、電圧が印加されると体積が変化する一方、外部から力を受けると電圧を発生する特性のことである。超音波発振素子１１の両面にはそれぞれ、ほぼ全面に印刷された電極が設けられている。超音波発振素子１１は、両面の電極間に、図１に示すリード線３を介して外部の電気回路から電圧が印加されると、上述したピエゾ効果により板厚方向である中心軸Ａ方向に振動することにより超音波を発振する。 The ultrasonic oscillator 11 is an element that transmits and receives ultrasonic waves. The ultrasonic oscillating element 11 is made of a material having a piezoelectric effect, such as PZT, and has a disk shape. The piezo effect is a characteristic in which a volume changes when a voltage is applied, and a voltage is generated when an external force is applied. Electrodes printed on substantially the entire surface are provided on both surfaces of the ultrasonic oscillator 11. When a voltage is applied from an external electric circuit between the electrodes on both sides via the lead wire 3 shown in FIG. Ultrasonic waves are generated by vibrating.
　弾性体１４は、超音波発振素子１１の中心軸Ａと同軸に配置された概略円柱状の部材である。軸方向両側の２つの端面のうち、第１の面が超音波発振素子１１に当接しており、第２の面が後述するケース１５の蓋部１５２に当接している。弾性体１４は、例えば柔軟な樹脂やゴムなどの弾性材料で形成されている。 The elastic body 14 is a substantially cylindrical member arranged coaxially with the central axis A of the ultrasonic oscillator 11. Of the two end surfaces on both sides in the axial direction, the first surface is in contact with the ultrasonic oscillator 11 and the second surface is in contact with the lid portion 152 of the case 15 which will be described later. The elastic body 14 is formed of an elastic material such as soft resin or rubber.
　ケース１５は、超音波発振素子１１及び弾性体１４を収容する収容室１６を形成する。ケース１５は、底部１５１と、蓋部１５２と、外周部１５３とを有する。底部１５１は、超音波発振素子１１の超音波を送受信する面１１１（以下、「おもて面１１１」と称す）側に設けられる。蓋部１５２は、超音波発振素子１１の超音波を送受信する面１１１と反対の面１１２（以下、「裏面１１２」と称す）側に設けられる。外周部１５３は、底部１５１と蓋部１５２との間に設けられ、底部１５１と蓋部１５２とともに収容室１６を画定する。底部１５１及び外周部１５３は、有底円筒状に一体に形成されており、蓋部１５２はこれらと別体である。蓋部１５２は、外周部１５３に設けられた爪に蓋部１５２に設けられた穴又は溝が引っかかることにより、外周部１５３に固定される。蓋部１５２が外周部１５３に固定された状態において、弾性体１４は、蓋部１５２により圧縮され弾性変形した状態でケース１５の収容室１６に収容されるように、中心軸Ａの方向における寸法が大きめに設計されている。このため、超音波発振素子１１は、弾性体１４の弾性力によりケース１５の底面に押し付けられた状態で固定される。 The case 15 forms a housing chamber 16 for housing the ultrasonic oscillator 11 and the elastic body 14. The case 15 has a bottom portion 151, a lid portion 152, and an outer peripheral portion 153. The bottom portion 151 is provided on the surface 111 (hereinafter, referred to as “front surface 111”) side of the ultrasonic oscillator 11 that transmits and receives ultrasonic waves. The lid portion 152 is provided on the surface 112 (hereinafter, referred to as “rear surface 112”) opposite to the surface 111 of the ultrasonic oscillator 11 that transmits and receives ultrasonic waves. The outer peripheral portion 153 is provided between the bottom portion 151 and the lid portion 152, and defines the storage chamber 16 together with the bottom portion 151 and the lid portion 152. The bottom portion 151 and the outer peripheral portion 153 are integrally formed in a bottomed cylindrical shape, and the lid portion 152 is a separate body from these. The lid portion 152 is fixed to the outer peripheral portion 153 by the holes or grooves provided in the lid portion 152 being caught by the claws provided on the outer peripheral portion 153. The dimension in the direction of the central axis A so that the elastic body 14 is housed in the housing chamber 16 of the case 15 while being compressed and elastically deformed by the lid 152 when the lid 152 is fixed to the outer peripheral portion 153. Is designed to be large. Therefore, the ultrasonic oscillator 11 is fixed in a state of being pressed against the bottom surface of the case 15 by the elastic force of the elastic body 14.
　接続部材１３は、超音波発振素子１１に取り付けられ、超音波発振素子１１と外部接続端子１７とを電気的に接続する端子である。接続部材１３は金属板で形成されている。 The connection member 13 is a terminal that is attached to the ultrasonic oscillator 11 and electrically connects the ultrasonic oscillator 11 and the external connection terminal 17. The connection member 13 is formed of a metal plate.
　本実施形態の液面検出装置１００は、図２に示すように、接続部材１３として、第１の接続部材１３１と第２の接続部材１３２とを備えている。第１の接続部材１３１と第２の接続部材１３２とは、弾性体１４を挟んで対向する位置に設けられている。図１においては、第１の接続部材１３１は手前側に設けられ、第２の接続部材１３２は奥側に設けられている。 As shown in FIG. 2, the liquid level detection device 100 of this embodiment includes a first connecting member 131 and a second connecting member 132 as the connecting member 13. The first connecting member 131 and the second connecting member 132 are provided at positions facing each other with the elastic body 14 interposed therebetween. In FIG. 1, the first connection member 131 is provided on the front side, and the second connection member 132 is provided on the back side.
　第１の接続部材１３１は、その一端が、図２に示すように、超音波発振素子１１のおもて面１１１と裏面１１２とを挟んで保持する、挟持部１３１ａとなっている。第２の接続部材１３２も同様である。超音波発振素子１１の裏面１１２と挟持部１３１ａとの間にはインシュレータ１２が介在しており、挟持部１３１ａは超音波発振素子１１の裏面１１２とは直接接触しない。一方、超音波発振素子１１の裏面１１１と第２の接続部材１３２の挟持部１３２ａとの間にもインシュレータ１２が介在しており、挟持部１３２ａは、超音波発振素子１１の裏面１１２とは直接接触していない。インシュレータ１２は、例えば樹脂材料やセラミックス材料などの絶縁材料で形成されている。なお、第１の接続部材１３１はグランド側の端子である。すなわち、第１の接続部材１３１は接地されている。 As shown in FIG. 2, one end of the first connection member 131 serves as a holding portion 131a that holds the front surface 111 and the back surface 112 of the ultrasonic oscillator 11 between them. The same applies to the second connecting member 132. The insulator 12 is interposed between the back surface 112 of the ultrasonic oscillation element 11 and the sandwiching portion 131a, and the sandwiching portion 131a does not directly contact the back surface 112 of the ultrasonic oscillation element 11. On the other hand, the insulator 12 is also interposed between the back surface 111 of the ultrasonic oscillation element 11 and the sandwiching portion 132a of the second connecting member 132, and the sandwiching portion 132a directly contacts the back surface 112 of the ultrasonic oscillation element 11. Not in contact. The insulator 12 is made of an insulating material such as a resin material or a ceramic material. The first connecting member 131 is a ground-side terminal. That is, the first connecting member 131 is grounded.
　以下、第１の接続部材１３１と第２の接続部材１３２とは、同様の構成を有するため、第１の接続部材１３１についてのみ説明する。 Since the first connecting member 131 and the second connecting member 132 have the same configuration, only the first connecting member 131 will be described below.
　図２に示すように、第１の接続部材１３１は、超音波発振素子１１から蓋部１５２に向かって延びている。具体的には、第１の接続部材１３１は、中心軸Ａに沿う方向に延びている。また、第１の接続部材１３１は、弾性体１４とケース１５の外周部１５３との間に設けられ、ケース１５の外周部１５３の内面に沿っている。第１の接続部材１３１における挟持部１３１ａと反対側の端部は、蓋部１５２に設けられた孔１８を通って、収容室１６の外側へ突出している。また、第１の接続部材１３１における、収容室１６の外側へ突出している端部は、外部接続端子１７と接続している。図１に示すように、第１の接続部材１３１において、外部接続端子１７と接続する端部と、挟持部１３１ａとの間は、中心軸Ａに沿う方向に対して波状に湾曲した構造になっている。これは、超音波発振素子１１に第１の接続部材１３１を取り付ける際に、挟持部１３１ａが超音波発振素子１１を挟む位置がずれないように、第１の接続部材１３１に加わる外力を吸収するためである。 As shown in FIG. 2, the first connecting member 131 extends from the ultrasonic oscillator 11 toward the lid 152. Specifically, the first connecting member 131 extends in the direction along the central axis A. The first connecting member 131 is provided between the elastic body 14 and the outer peripheral portion 153 of the case 15, and extends along the inner surface of the outer peripheral portion 153 of the case 15. An end portion of the first connection member 131 on the opposite side to the sandwiching portion 131 a passes through the hole 18 provided in the lid portion 152 and projects to the outside of the accommodation chamber 16. Further, the end portion of the first connection member 131 protruding outside the accommodation chamber 16 is connected to the external connection terminal 17. As shown in FIG. 1, in the first connection member 131, the end portion connected to the external connection terminal 17 and the sandwiching portion 131a have a wavy curved structure in the direction along the central axis A. ing. This is because when the first connecting member 131 is attached to the ultrasonic oscillator 11, the external force applied to the first connecting member 131 is absorbed so that the holding portion 131a does not shift the position where the ultrasonic oscillator 11 is sandwiched. This is because.
　ここで、ケース１５は樹脂製である。ケース１５が例えば金属製である場合、第１の接続部材１３１がケース１５の外周部１５３の内面に沿って設けられているため、短絡する可能性がある。また、ケース１５が金属製である場合、超音波発振素子１１から送信された超音波が、ケース１５の底部１５１で反射してしまうことがある。本実施形態ではケース１５は絶縁性の樹脂材料で形成されている。 Here, the case 15 is made of resin. When the case 15 is made of metal, for example, the first connecting member 131 is provided along the inner surface of the outer peripheral portion 153 of the case 15, and thus there is a possibility of a short circuit. When the case 15 is made of metal, the ultrasonic wave transmitted from the ultrasonic oscillator 11 may be reflected by the bottom 151 of the case 15. In this embodiment, the case 15 is made of an insulating resin material.
　次に、ハウジング部２について説明する。ハウジング部２は、全体として超音波の伝播経路として機能するアセンブリである。図１に示すように、ハウジング部２は、ボディ２１と、第１の金属管２２と、第２の金属管２３と、反射板２４とを有する。 Next, the housing part 2 will be described. The housing part 2 is an assembly that functions as an ultrasonic wave propagation path as a whole. As shown in FIG. 1, the housing part 2 includes a body 21, a first metal tube 22, a second metal tube 23, and a reflector 24.
　ボディ２１は、センサ部１、第１の金属管２２、第２の金属管２３及び反射板２４を保持及び固定する樹脂製の部材である。第１の金属管２２、第２の金属管２３及び反射板２４は、ボディ２１に装着されている。ボディ２１は、タンク２００の底面に固定されている。センサ部１は、超音波発振素子１１の中心軸Ａが第１の金属管２２の中心軸Ａと同軸となるようにボディ２１に取り付けられている。 The body 21 is a resin member that holds and fixes the sensor unit 1, the first metal tube 22, the second metal tube 23, and the reflection plate 24. The first metal tube 22, the second metal tube 23, and the reflector 24 are attached to the body 21. The body 21 is fixed to the bottom surface of the tank 200. The sensor unit 1 is attached to the body 21 so that the central axis A of the ultrasonic oscillator 11 is coaxial with the central axis A of the first metal tube 22.
　第１の金属管２２は金属製の筒である。本実施形態では、第１の金属管２２はステンレス鋼製である。第１の金属管２２は、伝播管部２２１と、延長管部２２２とを有する。 The first metal tube 22 is a metal tube. In this embodiment, the first metal tube 22 is made of stainless steel. The first metal pipe 22 has a propagation pipe portion 221 and an extension pipe portion 222.
　伝播管部２２１は、概略円錐台状の筒である。伝播管部２２１の、中心軸Ａと直交する面における断面は円形である。 The propagation tube portion 221 is a substantially frustoconical tube. The cross section of the propagation tube portion 221 in a plane orthogonal to the central axis A is circular.
　伝播管部２２１は、超音波の伝播経路であってケース１５の底部１５１から延びる第１の伝播経路４を形成する。第１の伝播経路４は、ケース１５の底部１５１から、中心軸Ａに沿って、ケース１５の蓋部１５２と反対側に向かって延びている。第１の伝播経路４は、円錐部４１と、直線部４２と、段部４３とを有する。円錐部４１は、超音波発振素子１１から離れるにつれて断面積が徐々に縮小する円錐台状の部分である。換言すると、円錐部４１は、中心軸Ａと直交する面における断面の直径が、超音波発振素子１１から離れるにつれて縮小する。直線部４２は、断面積が一定、つまり直管状の部分である。段部４３は、円錐部４１と直線部４２とを連結する部分であって、円錐部４１における超音波発振素子１１が設けられる端部と反対側の端部においてステップ状に断面積が縮小する部分である。段部４３の存在により、第１の金属管２２には、円環状の基準面２２３が形成されている。 The propagation pipe portion 221 forms a first propagation path 4 which is a propagation path of ultrasonic waves and extends from the bottom portion 151 of the case 15. The first propagation path 4 extends from the bottom portion 151 of the case 15 along the central axis A toward the side opposite to the lid portion 152 of the case 15. The first propagation path 4 has a conical portion 41, a linear portion 42, and a step portion 43. The conical portion 41 is a truncated cone-shaped portion whose cross-sectional area gradually decreases with distance from the ultrasonic oscillator 11. In other words, the diameter of the cross section of the conical portion 41 in the plane orthogonal to the central axis A decreases as the distance from the ultrasonic oscillation element 11 increases. The straight portion 42 has a constant cross-sectional area, that is, a straight tubular portion. The step portion 43 is a portion that connects the conical portion 41 and the linear portion 42, and the cross-sectional area is reduced stepwise at the end portion of the conical portion 41 opposite to the end portion where the ultrasonic oscillator 11 is provided. It is a part. Due to the presence of the step portion 43, an annular reference surface 223 is formed in the first metal pipe 22.
　延長管部２２２は、第１の金属管２２において、伝播管部２２１から延長された部分である。延長管部２２２は、具体的には、第１の接続部材１３１及び第２の接続部材１３２の少なくとも一部が延長管部２２２内に存在するように、伝播管部２２１から延長されている。具体的には、延長管部２２２は、伝播管部２２１から、中心軸Ａに沿って、ケース１５の蓋部１５２に向かって延びている。本実施形態では、図２の矢印Ｃに示すように、延長管部２２２は、伝播管部２２１から、収容室１６における蓋部１５２側の端１６１を越え、蓋部１５２の厚さ方向、すなわち中心軸Ａに沿う方向の途中まで延長されている。また、延長管部２２２は、ケース１５の外周部１５３の外側を覆っている。本実施形態では、延長管部２２２は、ケース１５の外周部１５３の全周を覆っている。 The extension pipe part 222 is a part of the first metal pipe 22 extended from the propagation pipe part 221. The extension pipe part 222 is specifically extended from the propagation pipe part 221 so that at least a part of the first connection member 131 and the second connection member 132 is present in the extension pipe part 222. Specifically, the extension pipe portion 222 extends from the propagation pipe portion 221 along the central axis A toward the lid portion 152 of the case 15. In the present embodiment, as shown by an arrow C in FIG. 2, the extension pipe portion 222 extends from the propagation pipe portion 221 to the end 161 on the lid portion 152 side of the accommodation chamber 16 and in the thickness direction of the lid portion 152, that is, It extends part way in the direction along the central axis A. The extension tube portion 222 covers the outer side of the outer peripheral portion 153 of the case 15. In the present embodiment, the extension pipe portion 222 covers the entire circumference of the outer peripheral portion 153 of the case 15.
　第２の金属管２３は、直管状の金属製の筒である。本実施形態では、第２の金属管２３はステンレス鋼製である。第２の金属管２３は、第２の金属管２３の中心軸Ｂが中心軸Ａと直交し、かつ第１の金属管２２における直線部４２側の端部と、ボディ２１を介して連続するように設けられている。第２の金属管２３は、中心軸Ｂと直交する面における断面が円形である。第２の金属管２３の上方端部は、タンク２００の燃料の貯蔵量が最大時における液面よりも、所定長さだけ上方に突出するように位置する。第２の金属管２３は、超音波の伝播経路の一部である第２の伝播経路５を形成している。第２の伝播経路５は、タンク２００の底部から液面に向かって延びている。具体的には、第２の伝播経路５は、タンク２００の底部から鉛直方向に延びている。本実施形態における第２の伝播経路５の直径は、直線部４２の直径と等しい。 The second metal tube 23 is a straight metal tube. In this embodiment, the second metal tube 23 is made of stainless steel. The center axis B of the second metal tube 23 is orthogonal to the center axis A, and the second metal tube 23 is continuous with the end of the first metal tube 22 on the side of the straight portion 42 via the body 21. Is provided. The second metal tube 23 has a circular cross section in a plane orthogonal to the central axis B. The upper end portion of the second metal pipe 23 is located so as to project upward by a predetermined length from the liquid level when the amount of fuel stored in the tank 200 is maximum. The second metal tube 23 forms the second propagation path 5 which is a part of the propagation path of ultrasonic waves. The second propagation path 5 extends from the bottom of the tank 200 toward the liquid surface. Specifically, the second propagation path 5 extends vertically from the bottom of the tank 200. The diameter of the second propagation path 5 in this embodiment is equal to the diameter of the straight portion 42.
　反射板２４は、金属製の板である。反射板２４は、ボディ２１に保持及び固定された状態において、第１の金属管２２の中心軸Ａと第２の金属管２３の中心軸Ｂとが、反射板２４の反射面２４１にて交差するように配置されている。反射板２４は、超音波発振素子１１から送信された超音波を燃料の液面に向けて反射する。具体的には、反射板２４は、第１の金属管２２の中心軸Ａに沿って進む超音波を、液面への入射角が０°となる方向、すなわち液面に直交する方向に向けて反射するように設置されている。本実施形態では、反射板２４は、液面に対して４５°傾斜するように設けられている。 The reflector 24 is a metal plate. When the reflector 24 is held and fixed to the body 21, the central axis A of the first metal tube 22 and the central axis B of the second metal tube 23 intersect at the reflecting surface 241 of the reflector 24. It is arranged to. The reflection plate 24 reflects the ultrasonic waves transmitted from the ultrasonic oscillator 11 toward the liquid surface of the fuel. Specifically, the reflector 24 directs the ultrasonic waves traveling along the central axis A of the first metal tube 22 in the direction in which the incident angle to the liquid surface is 0°, that is, in the direction orthogonal to the liquid surface. It is installed so that it reflects. In this embodiment, the reflection plate 24 is provided so as to be inclined at 45° with respect to the liquid surface.
　以上のような構成により、リード線３、外部接続端子１７、第１の接続部材１３１及び第２の接続部材１３２を介して超音波発振素子１１にパルス状電圧が印加されると、超音波発振素子１１が振動し、ケース１５の底部１５１を介して超音波が第１の伝播経路４に送信される。反射板２４を介し液面で反射した反射波又は基準面２２３で反射した反射波をセンサ部１が受信すると、その圧力作用によりケース１５の底部１５１が振動し、これに伴い超音波発振素子１１も振動する。これにより、超音波発振素子１１は電圧を発生し、当該電圧が第１の接続部材１３１、第２の接続部材１３２、外部接続端子１７及びリード線３を介して外部の電気回路に出力信号として入力される。 With the above configuration, when a pulsed voltage is applied to the ultrasonic oscillation element 11 via the lead wire 3, the external connection terminal 17, the first connection member 131, and the second connection member 132, ultrasonic oscillation is generated. The element 11 vibrates and ultrasonic waves are transmitted to the first propagation path 4 via the bottom portion 151 of the case 15. When the sensor unit 1 receives the reflected wave reflected by the liquid surface via the reflection plate 24 or the reflected wave reflected by the reference surface 223, the pressure action thereof causes the bottom portion 151 of the case 15 to vibrate, and the ultrasonic wave oscillating element 11 accordingly. Also vibrates. As a result, the ultrasonic oscillating element 11 generates a voltage, and the voltage is output as an output signal to the external electric circuit via the first connecting member 131, the second connecting member 132, the external connecting terminal 17 and the lead wire 3. Is entered.
　本実施形態では、グランド側の端子である第１の接続部材１３１と、延長管部２２２とが、電気的に接続されている。具体的には、図３に示すように、ケース１５の外周部１５３に設けられた貫通孔１５４を通る部材１９によって、第１の接続部材１３１と延長管部２２２とが電気的に接続されている。本実施形態では、部材１９はリード線である。なお、図２においては部材１９が図示されておらず、図３においてはインシュレータ１２が図示されていない。 In the present embodiment, the first connecting member 131, which is the ground side terminal, and the extension tube portion 222 are electrically connected. Specifically, as shown in FIG. 3, the first connecting member 131 and the extension pipe portion 222 are electrically connected by the member 19 passing through the through hole 154 provided in the outer peripheral portion 153 of the case 15. There is. In this embodiment, the member 19 is a lead wire. The member 19 is not shown in FIG. 2, and the insulator 12 is not shown in FIG.
　［２．効果］
　以上詳述した実施形態によれば、以下の効果が得られる。 [2. effect]
According to the embodiment described in detail above, the following effects can be obtained.
　（２ａ）第１の接続部材１３１及び第２の接続部材１３２の少なくとも一部が第１の金属管２２の延長管部２２２内に存在するため、第１の接続部材１３１及び第２の接続部材１３２が電気的にシールドされる。その結果、検出信号にのるノイズが低減される。 (2a) Since at least a part of the first connecting member 131 and the second connecting member 132 is present in the extension pipe portion 222 of the first metal pipe 22, the first connecting member 131 and the second connecting member. 132 is electrically shielded. As a result, noise on the detection signal is reduced.
　（２ｂ）延長管部２２２は、伝播管部２２１から少なくとも収容室１６におけるケース１５の蓋部１５２側の端１６１まで延長されている。すなわち、第１の接続部材１３１及び第２の接続部材１３２の大部分が延長管部２２２で覆われている。そのため、第１の接続部材１３１及び第２の接続部材１３２が、延長管部２２２によってより効果的に電気的にシールドされる。 (2b) The extension pipe portion 222 extends from the propagation pipe portion 221 to at least the end 161 of the housing 15 on the lid portion 152 side of the case 15. That is, most of the first connecting member 131 and the second connecting member 132 are covered with the extension pipe portion 222. Therefore, the first connecting member 131 and the second connecting member 132 are electrically shielded more effectively by the extension pipe portion 222.
　（２ｃ）第１の接続部材１３１は接地されており、第１の接続部材１３１と延長管部２２２とが電気的に接続されている。延長管部２２２がグランドに電気的に接続されているため、第１の接続部材１３１及び第２の接続部材１３２が、延長管部２２２によってより効果的に電気的にシールドされる。また、延長管部２２２を、すでに接地されている第１の接続部材１３１に接続するため、例えば延長管部２２２を接地するための配線を、新たに設けなくて済む。 (2c) The first connecting member 131 is grounded, and the first connecting member 131 and the extension pipe portion 222 are electrically connected. Since the extension pipe part 222 is electrically connected to the ground, the first connection member 131 and the second connection member 132 are electrically shielded by the extension pipe part 222 more effectively. Further, since the extension pipe part 222 is connected to the first connection member 131 which is already grounded, it is not necessary to newly provide a wiring for grounding the extension pipe part 222, for example.
　［３．他の実施形態］
　以上、本開示の実施形態について説明したが、本開示は、上記実施形態に限定されることなく、種々の形態を採り得ることは言うまでもない。 [3. Other Embodiments]
Although the embodiments of the present disclosure have been described above, it is needless to say that the present disclosure is not limited to the above embodiments and can take various forms.
　（３ａ）延長管部２２２の形状は上記実施形態に示される形状に限定されない。 (3a) The shape of the extension pipe portion 222 is not limited to the shape shown in the above embodiment.
　具体的には、上記実施形態では、延長管部２２２がケース１５の外周部１５３の全周を覆っているが、延長管部２２２が必ずしも外周部１５３の全周を覆っていなくてもよい。例えば、外周部１５３の全周を延長管部２２２が部分的に覆っていてもよい。具体的には、延長管部２２２がパンチングメタルで形成されたり、網状になっていたりしてもよい。このような場合において、外周部１５３の全周のうち延長管部２２２で覆われている部分の割合は、生じるノイズの強度が所望の値以下となるように、ノイズの発生源の位置などに応じて適宜設定することができる。生じるノイズをより効果的に低減するため、外周部１５３の全周のうち延長管部２２２で覆われている割合は大きい方が好ましい。そのため、延長管部２２２が外周部１５３の全周を覆うことが好ましい。 Specifically, in the above embodiment, the extension pipe part 222 covers the entire circumference of the outer peripheral part 153 of the case 15, but the extension pipe part 222 does not necessarily have to cover the entire circumference of the outer peripheral part 153. For example, the extension pipe portion 222 may partially cover the entire circumference of the outer peripheral portion 153. Specifically, the extension tube portion 222 may be formed of punching metal or may have a mesh shape. In such a case, the ratio of the portion covered by the extension pipe portion 222 to the entire circumference of the outer peripheral portion 153 depends on the position of the noise generation source or the like so that the intensity of generated noise is equal to or less than a desired value. It can be set as appropriate. In order to reduce the generated noise more effectively, it is preferable that the ratio of being covered by the extension pipe portion 222 in the entire circumference of the outer peripheral portion 153 is large. Therefore, it is preferable that the extension pipe portion 222 covers the entire circumference of the outer peripheral portion 153.
　また、上記実施形態では、延長管部２２２の端部は、円管を中心軸Ａに垂直な面で切断した形状であるが、延長管部２２２の端部の形状はこれに限定されない。例えば、延長管部２２２の端部が、円管を中心軸Ａに対し傾いた面で切断した形状であってもよい。延長管部２２２の端部の形状は、生じるノイズの強度が所望の値以下となる範囲で、センサ部１を構成する他の部材の配置、ノイズの発生源の位置などに応じて適宜設定することができる。 Further, in the above-described embodiment, the end portion of the extension pipe portion 222 has a shape obtained by cutting a circular pipe along a plane perpendicular to the central axis A, but the shape of the end portion of the extension pipe portion 222 is not limited to this. For example, the end portion of the extension pipe portion 222 may have a shape obtained by cutting a circular pipe along a surface inclined with respect to the central axis A. The shape of the end portion of the extension tube portion 222 is appropriately set in accordance with the arrangement of other members constituting the sensor portion 1, the position of the noise generation source, etc. within a range in which the intensity of generated noise is less than or equal to a desired value. be able to.
　（３ｂ）上記実施形態では、第１の接続部材１３１と延長管部２２２とを電気的に接続する部材１９がリード線であるが、部材１９はこれに限定されない。例えば、部材１９としてリード線にかえて端子を用いてもよい。また、第１の接続部材１３１の一部を部材１９としてもよい。 (3b) In the above embodiment, the member 19 that electrically connects the first connection member 131 and the extension tube portion 222 is a lead wire, but the member 19 is not limited to this. For example, a terminal may be used as the member 19 instead of the lead wire. Further, a part of the first connecting member 131 may be the member 19.
　（３ｃ）上記実施形態では、延長管部２２２が第１の接続部材１３１を介して接地されているが、延長管部２２２が第１の接続部材１３１を介さずに接地されていてもよい。 (3c) In the above embodiment, the extension pipe part 222 is grounded via the first connecting member 131, but the extension pipe part 222 may be grounded not via the first connecting member 131.
　（３ｄ）上記実施形態では、第１の接続部材１３１と延長管部２２２とが、ケース１５の外周部１５３に設けられた貫通孔１５４を通る部材１９によって、電気的に接続されている。しかし、第１の接続部材１３１と延長管部２２２との接続方法はこれに限定されない。例えば、延長管部２２２の一部を、蓋部１５２を貫通して突出するまで延長させ、その突出させた部分と、グランドに接続する外部接続端子１７とを、接続してもよい。また、外周部１５３と蓋部１５２との間を通る部材によって、第１の接続部材１３１と延長管部２２２とを接続してもよい。 (3d) In the above embodiment, the first connection member 131 and the extension pipe portion 222 are electrically connected by the member 19 that passes through the through hole 154 provided in the outer peripheral portion 153 of the case 15. However, the method of connecting the first connecting member 131 and the extension pipe portion 222 is not limited to this. For example, a part of the extension pipe part 222 may be extended until it penetrates through the lid part 152 to project, and the projecting part and the external connection terminal 17 connected to the ground may be connected. Further, the first connecting member 131 and the extension pipe portion 222 may be connected by a member that passes between the outer peripheral portion 153 and the lid portion 152.
　（３ｅ）上記実施形態では、第１の金属管２２及び第２の金属管２３がステンレス鋼製であるが、第１の金属管２２及び第２の金属管２３を構成する金属はこれに限定されない。例えば、金属として、鉄、アルミニウム、並びにこれらに対してＮｉめっき及びＺｎめっきなどのめっき処理を施したものが挙げられる。 (3e) In the above embodiment, the first metal pipe 22 and the second metal pipe 23 are made of stainless steel, but the metal forming the first metal pipe 22 and the second metal pipe 23 is not limited to this. Not done. Examples of the metal include iron, aluminum, and those obtained by subjecting these to plating treatment such as Ni plating and Zn plating.
　（３ｆ）上記実施形態では、ケース１５が絶縁性の樹脂材料で形成されているが、ケース１５の材質はこれに限定されない。例えば、ケース１５は導電性の樹脂材料で形成されていてもよい。 (3f) In the above embodiment, the case 15 is made of an insulating resin material, but the material of the case 15 is not limited to this. For example, the case 15 may be made of a conductive resin material.
　（３ｇ）上記実施形態における１つの構成要素が有する機能を複数の構成要素として分散させたり、複数の構成要素が有する機能を１つの構成要素に統合したりしてもよい。また、上記実施形態の構成の一部を省略してもよい。また、上記実施形態の構成の少なくとも一部を、他の上記実施形態の構成に対して付加、置換などしてもよい。 (3g) The function of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other above embodiment.

Claims (5)

  1. 　液面の位置を検出する液面検出装置（１００）であって、
    　超音波を送受信可能な超音波発振素子（１１）と、
    　前記超音波発振素子を収容する収容室（１６）を形成するケース（１５）であって、前記超音波発振素子の超音波を送受信する面側に設けられた底部（１５１）と、前記超音波発振素子の超音波を送受信する面と反対の面側に設けられた蓋部（１５２）と、前記底部と前記蓋部との間に設けられ、前記底部と前記蓋部とともに前記収容室を画定する外周部（１５３）と、を有する前記ケースと、
    　超音波の伝播経路であって前記ケースの前記底部から延びる前記伝播経路（４）を形成する、金属管（２２）と、
    　前記超音波発振素子と電気的に接続し、前記超音波発振素子に取り付けられ、前記ケースの前記蓋部に向かって延びる接続部材（１３）と、
    　を備え、
    　前記金属管は、前記金属管における前記伝播経路を形成する部分（２２１）から延長された延長管部（２２２）を有し、
    　前記接続部材の少なくとも一部が前記延長管部内に存在する、液面検出装置。     A liquid level detection device (100) for detecting the position of a liquid level, comprising:
    An ultrasonic oscillating element (11) capable of transmitting and receiving ultrasonic waves,
    A case (15) forming an accommodation chamber (16) for accommodating the ultrasonic oscillating element, the bottom (151) being provided on a surface of the ultrasonic oscillating element for transmitting and receiving ultrasonic waves, and the ultrasonic wave. A lid portion (152) provided on the surface side of the oscillator element opposite to the surface for transmitting and receiving ultrasonic waves, and is provided between the bottom portion and the lid portion, and defines the accommodation chamber together with the bottom portion and the lid portion. An outer peripheral portion (153) for
    A metal tube (22) forming an ultrasonic wave propagation path extending from the bottom of the case (4);
    A connection member (13) electrically connected to the ultrasonic oscillation element, attached to the ultrasonic oscillation element, and extending toward the lid portion of the case;
    Equipped with
    The metal pipe has an extension pipe portion (222) extended from a portion (221) forming the propagation path in the metal pipe,
    The liquid level detecting device, wherein at least a part of the connecting member exists in the extension pipe portion.
  2. 　前記延長管部は、前記金属管の前記伝播経路を形成する部分から少なくとも前記収容室における前記ケースの前記蓋部側の端まで延長されている、請求項１に記載の液面検出装置。 The liquid level detecting device according to claim 1, wherein the extension pipe portion extends from a portion of the metal pipe forming the propagation path to at least an end of the housing chamber on the lid portion side.
  3. 　前記ケースは樹脂製であり、前記接続部材は、前記ケースの前記外周部の内面に沿っている、請求項１又は請求項２に記載の液面検出装置。 The liquid level detection device according to claim 1 or 2, wherein the case is made of resin, and the connecting member extends along the inner surface of the outer peripheral portion of the case.
  4. 　前記接続部材は接地されており、
    　前記接続部材と前記金属管とが電気的に接続されている、請求項１～請求項３のいずれか１項に記載の液面検出装置。     The connection member is grounded,
    The liquid level detection device according to claim 1, wherein the connection member and the metal pipe are electrically connected.
  5. 　前記延長管部は、前記ケースの前記外周部の外側を覆う、請求項１～請求項４のいずれか１項に記載の液面検出装置。 The liquid level detection device according to any one of claims 1 to 4, wherein the extension pipe portion covers the outside of the outer peripheral portion of the case.
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