JPS618603A - Position detecting device - Google Patents

Abstract

PURPOSE:To detect the position of a mobile body with good accuracy by generating a DC signal correctly corresponding to the position of a mobile body even the frequency, peak value, etc. of an oscillator being varied. CONSTITUTION:The titled device is constituted of No. 1 ideal diode circuit 4 rectifying the half-wave of the output S1 of a transmitter 3, No. 2 ideal diode circuit 5 performing the half-wave rectifying with a different polarity from that of the half-wave rectifying of the circuit 4 of the output S2 of the prescribed place p of a detecting coil 2 and the integration circuit 6 rectifying the all-wave of the outputs S3, S4 of the circuits 4, 5. Since the output S3 of the circuit 4 is taken out, the plus half-wave only is turned over to negative with 1/2 of the amplitude and the negative hald-wave becomes on the level of the standard voltage V0 accordingly. In regard to the output S2, similarly only the negative half- wave is turned over positive. The output S5 of a circuit 6 is made on the level of the regular reference voltage V0, therefore. It becomes similarly of the reference voltage V0 even in case of the peak value being changed with the change of the output of the transmitter 3 due to the change in temp., etc. and on the same level as the time of the normal operation of the transmitter, and the standard position of the mobile body is correctly corresponded to.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a position detection device that generates a signal according to the position of a movable body, and relates to a position detection device that can improve temperature characteristics.

[Prior art] As a fuel injection 111i1J 'IJ device for a diesel engine, the operating conditions of the engine are detected, the target position of the spill ring of the distribution type fuel injection pump is determined according to the detection result, and the target position and the spill ring are A system is known in which a spill ring is moved to a target position based on the deviation from the actual position.

Conventionally, a device for detecting the actual position of a spill ring has been equipped with one detection coil whose inductance changes depending on the position of a core interlocked with the spill ring, and an oscillator that drives this detection coil with alternating current. There is one in which the position output is taken out as a DC signal corresponding to the actual position of the spill ring via a diode rectifier circuit or the like.

However, in this type of position detection device, the level of the DC signal changes when the frequency and peak value of the oscillator change due to changes in concentration, etc., and the temperature characteristics of the forward voltage of the diode in the diode rectifier circuit are large. The output of the diode rectifier circuit is FIAr! 1, and as a result, it was difficult to accurately detect the actual position of the spill ring.

[Object of the invention] The present invention aims to detect the position of a movable body such as a spill ring with high accuracy, and in particular, it is an object of the present invention to detect the position of a movable body such as a spill ring. A position detection device capable of generating a signal is provided.

[Configuration of the Invention] As shown in FIG. 1, the configuration of the present invention, which has been made to achieve the above object, consists of a detection coil B whose inductance changes depending on the position relative to the movable body, and an alternating current between the detection coil B and the detection coil B. A position detection device that generates a signal corresponding to the position of the movable body A, comprising a driving oscillator C, a first ideal diode circuit for half-wave rectification of the output S1 of the oscillator C, and a detection coil B. a second ideal diode circuit E for half-wave rectifying the output S2 at a predetermined point p with a polarity different from the half-wave rectification by the first ideal diode circuit; and the first and second ideal diode circuits; Output S3 of E
, S4 are provided, and the position of the movable body A is detected as the output S5 of the integrating circuit F.

EXAMPLES] The present invention will be described below with reference to examples and drawings.

FIG. 2 is an electrical circuit diagram showing the configuration of an embodiment of the present invention.

In the figure, 1 is a core that is displaced according to the movement of a movable body (not shown), such as a spill ring of a fuel injection pump, 2 is a detection coil into which core 1 is inserted and whose inductance value changes according to the position of core 1, and 3 is a core that is displaced as the spill ring of a fuel injection pump moves. an oscillator that drives the detection coil 2 with alternating current and generates a sine wave voltage; 4
5 is a first ideal diode circuit that half-wave rectifies the output S1 of the oscillator 3, and 5 half-wave rectifies the output $2 at a predetermined point p of the detection coil 2 with a polarity different from the half-wave rectification by the first ideal diode circuit 4. Second ideal diode circuit for wave rectification, 6
are the output S3 of the first and second ideal diode circuits 4.5,
Integrating circuit that full-wave rectifies S4, 7 is the output S of integrating circuit 6
5 represents an amplifier circuit that amplifies 5.

The predetermined position ρ of the detection coil 2 is, for example, the center position as shown in the figure, and when the movable body is at the reference position, the center position of the core 1 coincides with the center position of the detection coil 2 as shown in the figure. It is configured as follows. When the movable body is at the reference position, the inductance value of the upper half of the detection coil 2 in the drawing is equal to the inductance value of the lower half of the detection coil 2. Note that the core 1 is displaced within the detection coil 2 as shown by the arrow in the figure in accordance with the movement of the movable body.

In the first and second ideal diode circuits 4.5, 40
．． 50 are operational amplifiers, 41.51 are DC cut capacitors, 42.52 are input resistors, 43.44.53.54 are feedback resistors, 45.55 are resistors, 46.47.56.5
7 represents a diode, 48, 49, 58, and 59 represent a phase compensation capacitor, and 0 represents a reference voltage of, for example, O volts. Further, the ratio of the resistance value R43 of the feedback resistor 43 to the resistance value R42 of the input resistor 42, that is, the amplification factor R43/R42, is set to 1/2, while the feedback resistor 53
The ratio of the resistance value R53 of the input resistor 52 to the resistance value R52 of the input resistor 52, that is, the amplification factor R53/R52 is set to 1.

In the integrating circuit 6, 90 is an operational amplifier;
1.62 is an input resistance, 63 is a feedback resistor, 64 is an integrating capacitor, and VO is a reference voltage.

In the amplifier circuit 7, 70 is an operational amplifier;
1 is the input resistance, 72 is the feedback resistance, 73 is the output resistance, vO
represents the reference voltage.

Next, an example of the operation of the position detection device configured as described above will be described with reference to the waveform diagram of FIG. 3.

When the movable body is in the reference position and the oscillator 3 is performing normal oscillation operation, the output S1 of the oscillator 3 and the output S2 at the center position p of the detection coil 2 are as shown in FIG. 3(a). This waveform is represented by a solid line 31a and another solid line S2a. Here, the amplitude of the output S2 is 1/2 of the amplitude of the output $1 because the inductance value in the upper half of the drawing of the detection coil 2 is equal to the inductance value in the lower half. 1. In the diode circuit 4, a diode 46 is connected between the feedback resistor 43 and the output side of the operational amplifier 4o, as shown in the figure (the anode is connected to the feedback resistor 43, and the cathode is connected to the operational amplifier 4o). As shown in the figure, another diode 47 is connected between the other feedback resistor 44 and the output side of the operational amplifier 40, and the anode is connected to the output side of the operational amplifier 40. , and the cathode is connected to the feedback resistor 44, and the resistance ratio between the feedback resistor 43 and the input resistor 42 is 1/2 as described above, and the connecting portion between the diode 46 and the feedback resistor 43 is Since the output S3 of the first ideal diode circuit 4 is taken out from (for example, Ov) level, and the output S3 of the first ideal diode circuit 4 is represented by a waveform as shown by 33a in FIG. 3(b).On the other hand, in the second ideal diode circuit 5, the feedback 53 and the output side of the operational amplifier 50, a diode 56 is wired as shown in the figure, the anode of which is connected to the output side of the operational amplifier 50, and the cathode connected to the feedback resistor 53.
Another diode 57 is connected between the other feedback resistor 54 and the output side of the operational amplifier 50 through wiring whose anode is connected to the feedback resistor 54 and whose cathode is connected to the output side of the operational amplifier 50, as shown in the figure. In addition, the resistance ratio between the feedback resistor 53, 54 and the input resistor 52 is 1 as described above, and the output S4 of the second ideal diode circuit 5 is taken out from the connection between the diode 56 and the feedback resistor 53. Therefore, the output S of the detection coil 2
Only the negative half-wave in 2 is inverted to positive with the same amplitude, and for the positive half-wave, the reference voltage ■0 level is set, and the output S4 of the second ideal diode circuit 5 is the solid line S4a in FIG. 3(C). It is represented by a waveform as shown in . Therefore, the negative half-wave of the output S3 and the positive half-wave of the output S4 have the same relationship as normal rotation and inversion of the same waveform. Therefore, the output S5 of the integrating circuit 6 and the output S5 of the amplifier circuit 7
6 are solid lines 35 a in FIG. 3(d), respectively.
As shown by SB a, the reference voltage (2) is always at the 0 level.

On the other hand, when the movable body is at the reference position, the output of the oscillator 3 fluctuates due to temperature changes, for example, the peak value decreases compared to normal operation, and the output $1 decreases to the dotted line in Fig. 3<a). When the waveform changes to the one shown in S1b, the output S2 of the detection coil 2 changes from the other dotted line S in FIG. 3(a).
Waveform as shown in 2b, ie, output S2 when the oscillator is operating normally.
When the amplitude of is multiplied by the variation ratio of the oscillator output S1, the waveform changes to the same as that of the oscillator output S1. Therefore, the outputs S3 and S4 of the first and second ideal diode circuits 4.5 are respectively shown in FIG.
The waveform changes to the waveform shown by the wavy line 3'3b in b) and the waveform shown by the wavy line 34b in FIG. 3(C).

However, the amplitude of each of these outputs 83 and S4 is the first
, the amplification factors of the second ideal diode circuit 4.5 are 1/2.1 as described above, so that they are equal to each other. Therefore, the output S5 of the integrating circuit 6 and the amplifier circuit 7
The output S6 of each wave 1i13 in FIG. 3(d)
5b and the dotted line S6b, the outputs S5 and SB during normal operation of the oscillator are at the same level as the reference voltage 0.

In this way, even if the peak value changes due to fluctuations in the output of the oscillator 3, the output S6 of the amplifier 7 remains at the same level as when the oscillator is in normal operation, and accurately corresponds to the reference position of the movable body.

Note that the above explanation of the operation was based on an example in which the output peak value of the oscillator changes when the movable body is at the reference position. However, when the movable body is at any position other than the reference position, Even if a high value change occurs, the output S of amplifier 7
It goes without saying that 6 is a level that accurately corresponds to the position of the movable body. Further, although a description of the operation will be omitted, even when the output frequency of the oscillator 3 changes, the amplifier circuit output S6 becomes a level that accurately corresponds to the position of the movable body, similarly to the above.

[Effects of the Invention] As explained above, according to the present invention, even if output fluctuations occur in the oscillator 3 due to temperature changes, it is possible to generate an output that accurately corresponds to the position of the movable body. It becomes possible to sufficiently improve detection accuracy.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram clearly showing the features of the present invention, FIG. 2 is an electric circuit diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a waveform diagram for explaining its operation. A...Movable body B, 2...Detection coil C, 3
...Oscillator, 4...First ideal diode circuit E15...Second ideal diode circuit F, 6...Integrator circuit
1...Core 7...Amplification circuit

Claims (1)

[Claims] A detection coil whose inductance changes depending on the position of a movable body, and an oscillator that drives the detection coil with alternating current,
In the position detection device that generates a signal corresponding to the position of the movable body, the first ideal diode circuit half-wave rectifies the output of the oscillator; a second ideal diode circuit that performs half-wave rectification with a polarity different from that of the half-wave rectification, and an integrating circuit that performs full-wave rectification of the outputs of the first and second ideal diode circuits, A position detection device characterized in that the detection is performed as an output of the integration circuit.