GB2062254A - Inductive Measuring Apparatus for a Controlling or Regulating Member, in Particular of an Internal Combustion Engine - Google Patents
Inductive Measuring Apparatus for a Controlling or Regulating Member, in Particular of an Internal Combustion Engine Download PDFInfo
- Publication number
- GB2062254A GB2062254A GB8035045A GB8035045A GB2062254A GB 2062254 A GB2062254 A GB 2062254A GB 8035045 A GB8035045 A GB 8035045A GB 8035045 A GB8035045 A GB 8035045A GB 2062254 A GB2062254 A GB 2062254A
- Authority
- GB
- United Kingdom
- Prior art keywords
- operational amplifier
- inverting input
- output
- measuring
- windings
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R17/00—Measuring arrangements involving comparison with a reference value, e.g. bridge
- G01R17/10—AC or DC measuring bridges
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2611—Measuring inductance
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
- Transmission And Conversion Of Sensor Element Output (AREA)
Abstract
The measuring coil (L1) and the reference coil (L2) of a short-circuit- ring transducer connected to an evaluating circuit are each divided into mutually magnetically coupled measurement windings (11 and 12) and mutually magnetically coupled reference windings (13 and 14). The evaluation circuit includes at least two operational amplifiers (O1 and O2) connected as shown to produce a square wave output whose period T is proportional to (L1-L2)/R. <IMAGE>
Description
SPECIFICATION
Inductive Measuring Apparatus for a
Controlling or Regulating Member, in
Particular of an Internal Combustion Engine
The invention relates to inductive measuring apparatus for the detection of the displacement of a controlling or regulating member, such as a controlling or regulating member associated with an internal combustion engine, comprising a short-circuit-ring transducer, which has a first coil whose (measurement) inductance is variable in dependence on the respective position of the magnetic flux short-circuit-ring, and a second coil having an independent (reference) inductance, the coils being connected to an electrical evaluation circuit in order to log the variable inductance.
In electronic diesel-engine control systems, for logging linear and angular displacements, for example, of the fuel quantity regulating rod of a fuel injection pump, it is possible to use shortcircuit-ring transducers in which the short-circuitring is mechanically coupled to the controlling or regulating member and performs identical movement thereto. The short-circuit-ring is displaceable along two parallel arms of a magnetic core, on which the coils are wound, so as to vary the length and thereby the reluctance of the magnetic flux path linking the measurement coil. Thus inductance of the measuring coil is varied in accordance with the displacement to be logged.
It is an object of the present invention to achieve, in a measuring apparatus of the abovementioned type, a variation in inductance for detecting as accurately as possible the actuating or controlling quantity, and to provide a simple circuit arrangement for evaluation of the variations in inductance.
The present invention resides in inductive measuring apparatus for the detection of the displacement of a controlling or regulating member which comprises a short-circuit-ring transducer, having a first coil whose (measurement) inductance is variable in dependence on the respective position of a magnetic flux short-circuit-ring and a second coil having an independent (reference) inductance, and an electrical evaluation circuit to which the coils are connected in order to log the variable inductance, and in which the first coil of variable inductance, is sub-divided into two magnetically coupled measuring windings, and the second coil of the reference inductance is sub-divided into two magnetically coupled reference windings, and the evaluation circuit has at least two serially arranged operational amplifiers the output of each of which is regeneratively connected or coupled to an inverting input, one of the two measuring windings being connected to the inverting input of the first operational amplifier and the other of the two measuring windings being arranged in a connection between the output of the first operational amplifier and the inverting input of the second operational amplifier.
The invention is further described, by way of example, with reference to the drawings in which Figs. 1 and 2 are of two embodiments of inductive measuring apparatus according to the invention.
The measuring apparatus shown serves to detect the displacement of a fuel quantity regulating rod (not shown) of a diesel-engine fuel injection pump of an internal combustion engine, and comprises a half-differential short-circuit-ring transducer (not shown in detail), whose magnetic flux short-circuit-ring is mechanically coupled to the controlling or regulating member to be monitored.
The short-circuit-ring transducer is provided with two magnetically-coupled measuring windings 11 and 12, and two reference windings 1 3 and 14, which are also magnetically coupled and have a fixed inductance L2. In contrast to these reference windings, the inductance L1 of the two measuring windings is varied between a maximum value and a minimum value according to the position of the short-circuit-ring.
As is evident from the circuit diagram of Figure
1, the evaluation circuit comprises a first operational amplifier 01 and a second operational amplifier 02 serially connected thereto, both of which are maintained at half the operating
voltage U9 at their non-inverting inputs by means of voltage dividers formed by equally-sized resistors of value R.
In the junction line between the output of the first operational amplifier 01 and a resistor R connected to the inverting input of the second operational amplifier 02 there is connected the series combination of the second measuring winding 12 and the second reference winding 14.
The latter is connected to the supply voltage U, and to earth via respective integrating resistors of value 2R. In order to achieve regenerative feedback, the first two winding halves 11 and 13, which are individually magnetically coupled respectively to the second measuring winding 12 and the second reference winding 14, are connected in a feedback circuit which is connected between the inverting input of the first operational amplifier 01 and the output of the second operational amplifier 02, so that at the output of the second operational amplifier there is produced a square-wave oscillation whose period
T is directly proportional to the difference between the measured inductance L1 and the reference inductance L2, namely:: L1-L2 T=const- R
In the embodiment of Figure 2, a third operational amplifier 03, whose non-inverting input is connected to a fraction of the operating voltage UB, is serially connected to the input of the first operational amplifier 01. To the inverting input of the operational amplifier 03 there is connected the first reference winding 13, whose other end is connected to the junction between a capacitor C, which is directly connected to the operating voltage U", and a resistor R connected to the output of the third operational amplifier 03.
The output of the third operational amplifier 03 is directly connected to the non-inverting input of the first operational amplifier 01. The output of the first operational amplifier 01 is connected by way of the second measuring winding 12 to the inverting input of the second operational amplifier 02 which in turn is connected via the second reference winding 14 to the output of the second operational amplifier 02. The first measuring winding 11, on the other hand, is connected to the inverting input of the first operational amplifier 01, its other end being connected to a fraction of the operating voltage UB.
Owing to the feedback, a square-wave oscillation, whose frequency
L1 f=const L2
is produced at the output of the second operational amplifier 02. The output voltage of the second operational amplifier can therefore be further directly processed by digital means, as is the case with the embodiment of Figure 1.
The particular advantage of the invention lies in the fact that the output voltages can be further processed directly by digital means. Furthermore, owing to the transformer-type coupling of the transducer inductances the effects of temperature on the individual inductances are eliminated. The control signals of the transducer inductances may closely approach the supply voltage U9, that is, they may have an amplitude U 2 so that a good signal-to-noise ratio is consequently achieved in the event of long connecting leads being used between the transducer and the evaluation circuit.
Claims (4)
1. Inductive measuring apparatus for the detection of the displacement of a controlling or regulating member which comprises a shortcircuit-ring transducer, having a first coil whose (measurement) inductance is variable in dependence on the respective position of a magnetic flux short-circuit-ring and a second coil having an independent (reference) inductance, and an electrical evaluation circuit to which the coils are connected in order to log the variable inductance, and in which the first coil of variable inductance, is sub-divided into two magnetically coupled measuring windings, and the second coil of the reference inductance is sub-divided into two magnetically coupled reference windings, and the evaluation circuit has at least two serially arranged operational amplifiers the output of each of which is regeneratively connected or coupled to an inverting input, one of the two measuring windings being connected to the inverting input of the first operational amplifier and the other of the two measuring windings being arranged in a connection between the output of the first operational amplifier and the inverting input of the second operational amplifier.
2. Measuring apparatus as claimed in claim 1, in which the first of the two reference windings is connected in series with the first of the two measuring windings, and this series circuit is arranged between the output of the second operational amplifier and the inverting input of the first operational amplifier, and in which the second reference winding is connected in series with the second measuring winding and this latter series circuit is connected to the output of the first operational amplifier.
3. Measuring apparatus as claimed in claim 1, in which the inverting input of a third operational amplifier, whose non-inverting input is connected to a fraction of the operating voltage, is connected to one end of the first reference winding and the output of the third operational amplifier is connected to the non-inverting input of the second operational amplifier, and via a resistor to the other end of the first reference winding and to a capacity connected to the operating voltage, and in which the second reference winding is connected between the inverting input and the output of the second operational amplifier and one end of the second measuring winding is connected to the inverting input of the first operational amplifier, its other end being connected to a fraction of the operating voltage.
4. Inductive measuring apparatus constructed and adapted to operate substantially as herein described with reference to and as illustrated in the drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792944463 DE2944463A1 (en) | 1979-11-03 | 1979-11-03 | INDUCTIVE MEASURING DEVICE FOR A CONTROL OR REGULATOR, ESPECIALLY AN INTERNAL COMBUSTION ENGINE |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2062254A true GB2062254A (en) | 1981-05-20 |
| GB2062254B GB2062254B (en) | 1983-06-22 |
Family
ID=6085090
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8035045A Expired GB2062254B (en) | 1979-11-03 | 1980-10-31 | Inductive measuring apparatus for a controlling or regulating member in particular of an internal combustion engine |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5674613A (en) |
| DE (1) | DE2944463A1 (en) |
| FR (1) | FR2468884A1 (en) |
| GB (1) | GB2062254B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4523562A (en) * | 1982-07-05 | 1985-06-18 | Daimler-Benz Aktiengesellschaft | Method for controlling the fuel metering for an internal combustion engine |
| US4852535A (en) * | 1987-10-01 | 1989-08-01 | Steyr-Daimler-Puch Ag | Automatic control method for moving a final control element |
| WO1989011105A1 (en) * | 1988-05-05 | 1989-11-16 | Robert Bosch Gmbh | Circuit for measuring variable inductance |
| US4915072A (en) * | 1988-07-14 | 1990-04-10 | Navistar International Transporation Corp. | Electronic governor interface module |
| DE3927833A1 (en) * | 1989-08-23 | 1991-02-28 | Bosch Gmbh Robert | MEASURING CIRCUIT AND APPLICATION THEREOF, IN PARTICULAR WITH INDUCTIVE WAYERS |
| US7492148B2 (en) | 2003-10-17 | 2009-02-17 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Circuit configuration for inductive displacement measurement |
-
1979
- 1979-11-03 DE DE19792944463 patent/DE2944463A1/en not_active Withdrawn
-
1980
- 1980-10-31 FR FR8023332A patent/FR2468884A1/en active Granted
- 1980-10-31 GB GB8035045A patent/GB2062254B/en not_active Expired
- 1980-11-04 JP JP15511080A patent/JPS5674613A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4523562A (en) * | 1982-07-05 | 1985-06-18 | Daimler-Benz Aktiengesellschaft | Method for controlling the fuel metering for an internal combustion engine |
| US4852535A (en) * | 1987-10-01 | 1989-08-01 | Steyr-Daimler-Puch Ag | Automatic control method for moving a final control element |
| WO1989011105A1 (en) * | 1988-05-05 | 1989-11-16 | Robert Bosch Gmbh | Circuit for measuring variable inductance |
| US4915072A (en) * | 1988-07-14 | 1990-04-10 | Navistar International Transporation Corp. | Electronic governor interface module |
| DE3927833A1 (en) * | 1989-08-23 | 1991-02-28 | Bosch Gmbh Robert | MEASURING CIRCUIT AND APPLICATION THEREOF, IN PARTICULAR WITH INDUCTIVE WAYERS |
| DE3927833C2 (en) * | 1989-08-23 | 1998-07-02 | Bosch Gmbh Robert | Measuring circuit and application of the same, especially with inductive displacement sensors |
| US7492148B2 (en) | 2003-10-17 | 2009-02-17 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Circuit configuration for inductive displacement measurement |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5674613A (en) | 1981-06-20 |
| GB2062254B (en) | 1983-06-22 |
| FR2468884A1 (en) | 1981-05-08 |
| FR2468884B1 (en) | 1984-11-23 |
| DE2944463A1 (en) | 1981-05-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 746 | Register noted 'licences of right' (sect. 46/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |