JP3330450B2 - Displacement detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement detector for detecting a displacement based on a change in inductance of a detection coil.

[0002]

2. Description of the Related Art A conventional displacement detector that detects displacement based on a change in impedance of a detection coil is known. FIGS. 11A and 11B show a main part configuration diagram of a conventional displacement detector. FIG. 11A shows a configuration diagram of the displacement detector, and FIG. 11B shows an equivalent circuit diagram.

FIG. 11 shows a conventional displacement detector 61.
Is the displacement corresponding to the displacement of the object (displacement amount x1, x2)
Sensor having a core 63 to be moved and two detection coils 62A and 62B arranged to surround the core 63 and symmetric in the direction of displacement, the detection coil 62A and the detection coil 62.
AC power supply V _S connected between a connection point connecting one end of B and ground (GND), and connected between the other ends (terminals D1 and D2) of detection coil 62A and detection coil 62B and ground (GND), respectively. And two reference resistors rf.

[0004] The conventional displacement detector 61 shown in FIG. 1A has the inductance L1 shown in FIG.
It is represented by an equivalent circuit of a bridge circuit in which each element of L2 and two reference resistances rf is one side. In addition,
The inductances L1 and L2 represent the inductances of the detection coils 62A and 62B when the core 63 is displaced by x1, for example, and when the core 63 is in the neutral position, the inductances L1 and L2 are equal (L1 = L2 = L).
Is set to

(B) When an AC power supply V _S (for example, a sine wave having a peak value V _I and a frequency f) is applied to the equivalent circuit shown in FIG.
Output voltages V _O1 and V ₀₂ corresponding to the change in impedance are detected.

[0006]

(Equation 1)

The detection output V ₀ corresponding to the displacement (x1, x2) of the core 63 is _{equal to the difference} between V _O1 and V ₀₂ (V _O1 −
V ₀₂ ). When there is no displacement of the core 63 (neutral position), inductances L1, L2 are equal (L1 = L2), corresponding detection output V ₀ impedance equal to is zero.

Thus, in the conventional displacement detector 61, when the core 63 of the displacement sensor is displaced in accordance with the displacement of the object, the inductances (L1, L2) of the detection coils 62A and 62B change. Since the corresponding impedance also changes, the displacement amount of the object can be detected by detecting the difference V ₀ between the voltages V _O1 and V _{02 by} the bridge circuit.

[0009]

The conventional displacement detector 61
Uses a change in the impedance of the detection coils 62A and 62B due to a change in the magnetic flux caused by the displacement (x1, x2) of the core 63, so that there is a problem that the change in the impedance cannot be detected efficiently.

The detection coil 6 at the neutral position of the core 63
The impedance (Z) of 2A and 62B is expressed by Equation 2 where L is the inductance of the detection coils (62A, 62B), r is the internal resistance, and f is the frequency of the AC power supply.

[0011]

(Equation 2)

As is apparent from Equation 2, the impedance Z is the vector sum of the internal resistance r and the reactance 2πf * L. To accurately detect the change ΔL in the inductance L, the impedance Z and the AC power It is necessary to reduce the frequency f of VS.

However, if the wires are wound to form the detection coils (62A, 62B), the internal resistance r increases. Further, in order to excite the bridge circuit and obtain a detection output, it is necessary to increase the frequency f, and if the frequency f is increased, the internal resistance r increases due to iron loss and the like.

As described above, the conventional displacement detector using the coil bridge has a problem that the impedance change due to the magnetic flux change cannot be accurately detected, and the displacement amount cannot be detected with high sensitivity.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a displacement detector capable of detecting a displacement amount of an object with high accuracy and high sensitivity.

[0016]

In order to solve the above problems, a displacement detector according to the present invention is capable of changing from a neutral position in both directions.
And a symmetrical core from the neutral position in the direction of core displacement
And inductance is differential according to the core displacement
And the two detection coils changing with
And two reference resistors connected in series to each of
A bridge composed of two reference resistors and two detection coils
Bridge circuit and pulse power applied to this bridge circuit
And the two ends of each of the two reference resistors in the bridge circuit.
Deviation voltage detecting means for detecting the deviation voltage of the transfer response voltage.
The core displacement and displacement direction based on the deviation voltage.
Output voltage, and the deviation voltage detecting means includes two reference resistances.
Detect the maximum value of the deviation of the transient response voltage at both ends.
From the large deviation voltage calculation means and the maximum deviation voltage calculation means
Displacement amount conversion means for converting the maximum deviation voltage of the
Characterized by comprising.

Further, the displacement detector according to the present invention has a neutral position.
A core that can be displaced in both directions from the position and a core that can be displaced from the neutral position
Are arranged symmetrically in the displacement direction of
Two detection coils whose conductance changes differentially
Connected in series to each of the two detection coils
Reference resistance, the two reference resistances and the two detection
And a bridge circuit composed of
And two reference resistors for the bridge circuit.
Detect the deviation voltage of the transient response voltage across each end
Deviation voltage detecting means, and two deviation voltage detecting means are provided.
Of the falling transient response voltage across each of the reference resistors
Falling maximum deviation voltage detecting means for detecting the maximum value of
Deviation of the rising transient response voltage across each of the two reference resistors.
Rising maximum deviation voltage detecting means for detecting the maximum value of the difference,
Output from the maximum falling deviation voltage detection means and maximum rising deviation
The deviation that outputs the maximum value deviation from the output from the differential voltage detection means
Difference output means and displacement for converting this maximum deviation into displacement
Volume conversion means .

Furthermore, the displacement detector according to the present invention, the medium
A core that can be displaced in both directions from the neutral position and a core that can be displaced from the neutral position
Are symmetrically arranged in the displacement direction of the
Two detection coils whose inductance changes differentially;
2 connected in series to each of the two detection coils
Reference resistances, the two reference resistances and the two detections
A bridge circuit composed of coils and this bridge circuit
Pulse power applied to the circuit and two references for the bridge circuit
Detects the deviation voltage of the transient response voltage across each resistor
Means for detecting the falling voltage of the pulse power supply.
Time is less than the time constant and the transient response voltage becomes 0V.
It is characterized in that it is set not to be .

[0019]

The displacement detector according to the present invention includes a displaceable core, a detection coil whose inductance changes according to the amount of displacement of the core, and a reference resistor, and applies a pulse power to correspond to the inductance and the reference resistance. Since the absolute value of the inductance can be detected by detecting the transient response voltage, the change in the inductance with respect to the displacement of the core can be detected by the transient response voltage.

Further, the displacement detector according to the present invention comprises a displaceable core, two detection coils whose inductance changes differentially according to the displacement of the core, two reference resistors, and a deviation voltage detecting means. A bridge circuit is configured with two detection coils and two reference resistors, a pulse power supply is applied to the bridge circuit, a transient response voltage of the bridge circuit output is detected, and a deviation voltage of the transient response voltage is deviated. Since the voltage is detected by the voltage detecting means, the differential change of the inductance with respect to the displacement of the core can be detected by the transient response voltage.

Furthermore, the difference voltage detection means of the displacement detector according to the present invention, the maximum deviation voltage calculating means for detecting a maximum value of the deviation of the transient response voltage, the amount of displacement the maximum deviation voltage from maximum deviation voltage calculating means The displacement amount converting means for converting the displacement amount into a displacement amount can be detected with a large voltage value.

Further, the difference voltage detection means of the displacement detector according to the invention, falling maximum difference voltage detection unit, rising up to the difference voltage detection unit, deviation output means includes a displacement conversion means, the falling of the pulse and Since the maximum value of the deviation of the transient response voltage at the time of rising is detected, and the deviation of each maximum value is detected and converted into the displacement amount, the displacement amount can be detected with a larger voltage value.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a displacement detector, and (a)
The figure shows the main configuration of the displacement detector, the figure (b) shows the equivalent circuit diagram,
(C) shows a transient response voltage waveform.

The displacement detector 1 includes a detection coil 2 and a displacement (X1, X2) corresponding to the displacement amount of the object inside the detection coil 2.
X2), a core 3 made of a non-magnetic material is provided. One end 2a of the detection coil 2 is connected to a pulse power source 5, and the other end 2b of the detection coil 2 is connected to a reference resistor R _{F. The} transient response voltage V _O is detected from both ends of _F (between 2b end and GND).

When the core 3 is in the neutral position of the detection coil 2, the inductance is L, and the reference resistance R _F is
If the internal resistance r is set to a value sufficiently larger than the internal resistance r, the internal resistance r can be ignored, and the equivalent circuit (integration circuit) shown in FIG. In the circuit of (b), a time period τ (= L / R _F ) in which a half cycle (T / 2) is determined by the inductance L and the reference resistance R _F
When driven by the falling voltage of a pulse power supply (peak value V _I ) that is sufficiently larger than the above, the transient response voltage V _O after the time t _K is expressed by Expression 3.

[0026]

(Equation 3)

On the other hand, the detection coil 2 core 3 and X1 displaced
Is driven by the falling voltage of the pulse power supply (peak value V _I ) in a state where the inductance of (L−ΔL) is reduced by ΔL, the transient response voltage V _O1 after the time t _K is expressed by _Expression 4.

[0028]

(Equation 4)

From the transient response voltage V _O (Equation 3) when the core 3 is in the neutral position (displacement amount is 0), the inductance L
Is calculated and stored, and the inductance (L-Δ) is calculated from the transient response voltage V _O1 ( _Equation 4) when the core 3 is displaced by X1.
L), the deviation is calculated, and the displacement X1 of the core 3 is calculated.
The amount of change ΔL of the inductance with respect to

[0030]

(Equation 5)

From equation (5), assuming that the time t _K is constant, the variation ΔL of the inductance corresponding to the displacement X1 of the core 3 indicates the transient response voltages V _O and V _O1 and the _peak value V _{I of the} pulse power supply 5.
And a value corresponding to the ratio.

[0032] Therefore, the amount of change ΔL of inductance,
The peak value V _I of the pulse power supply 5 and the frequency f = (1 /
T) can be detected with a value irrelevant to T), and the displacement X1 can be detected. Further, the amount of change ΔL of inductance, transient response voltage V _O, so corresponding to the V _O1, by detecting the transient response voltage V _O, V _O1, it is possible to detect the displacement amount X1.

Although the embodiment in which the pulse power supply 5 is driven by the falling voltage has been described above, even when the pulse power supply 5 is driven by the rising voltage, the transient response voltage corresponding to V _O and V _O1 is detected. Thus, the displacement X1 can be detected.

[0034] Thus, the displacement detector 1 can detect the displacement amount based on the transient response voltage.

Next, a description will be given displacement detector according to claim 1 to 3. FIG. 2 is a configuration diagram of a displacement detector according to claims 1 to 3 , wherein FIG. 2A is a configuration diagram of a displacement sensor, and FIG.
FIG. 3A shows a bridge circuit diagram including a detection coil and a reference resistor.

The displacement sensor 11 is arranged symmetrically in the direction of displacement of the core 13 with a core 13 made of a nonmagnetic material displaced in both directions from the neutral position, and the inductance changes differentially in accordance with the displacement of the core 13. constructed from the detection coil 12A and the detection coil 12B, connect one end of the detection coil 12A and the detection coil 12B, and connect the other end of the detection coil 12A and the detection coil 12B to one end of the reference resistor R _F, respectively, two more connect the other ends of the reference resistor R _F and ground (GND), comprising the bridge circuit 14 of an electrical equivalent circuit (b) and FIG.

Further , a pulse power supply 15 (peak value V _I ) is applied between the connection between the detection coil 12A and the detection coil 12B and the connection between the two reference resistors R _F , and the detection coil 12A and the reference resistance R _F are applied. connection of R _F, and the detection coil 12
B and the reference resistor R _F connection are connected to the detection terminals S 1 and S 2 respectively.
Take out as.

[0038] In the equivalent circuit of the (b) diagram, L1 detection coils 12A, 12B of the inductance, respectively, L2
Then, the bridge circuit 14 by applying the pulse power supply 15
Detection terminals S1 and S2 are ground terminals (GND), respectively.
LR integration circuit based on the detection voltages V _S1 and V
_S2 is a transient response voltage for pulse height V _I. The detection voltages V _D of the detection terminals S 1 and S 2 are equal to the detection voltages V _S1 and V _S2.
(V _S1 −V _S2 ).

FIG . 3 shows an embodiment of the displacement sensor. In FIG. 3, a displacement sensor 11 includes a core 13 movable in a longitudinal direction of a cylindrical case, and two detection coils 12 </ b> A and 12 </ b> B arranged in a moving direction of the core 13 and arranged symmetrically so as to surround the core 13. , Core 13, detection coil 1
It consists of a case that houses 2A and 12B. The wiring of the bridge circuit 14 is performed inside the case, the supply terminal V _I of the detection terminals S1, S2 and the pulse power source 15 shown in FIG. 2 is configured to take out the wiring to the outside of the case. The ground terminal (GND) may be grounded to the case, or may be provided inside the case similarly to the detection terminals S1 and S2, and may be taken out by wiring.

FIG . 4 shows a transient response voltage waveform diagram of the displacement detector according to the first to third aspects . (A) shows the transient response voltage waveform when the duty of the falling waveform and the rising waveform of the pulse power supply are equal, and (b) shows the transient response voltage waveform when the duty of the falling waveform and the rising waveform of the pulse power supply are different. Show. FIG. 3A shows that the period (T / 2) of the falling waveform of the pulse power supply is sufficiently longer than the time constant of the integrating circuit, and the time T
/ 2, the transient response voltage is set so as to reach 0 V. On the other hand, FIG.
1) is set short so that the transient response voltage does not become 0V. Further, (a) view and (b) in FIG both periods of the rising waveform of the pulse power is sufficiently longer than the time constant of the integrating circuit, the transient response voltage at time T or time T2 is the peak value V _I
Set to reach.

The object on which the displacement detector 10 is mounted is displaced, and the core 13 of the displacement sensor 11 shown in FIG. 2 is displaced by X1 from the neutral position to the detection coil 12A side. L (inductance at the neutral position) decreases to L1, and the detection coil 12
If the inductance L of B increases to L2,
Due to the relationship of inductance L1 <L2, the time constant (L1 / R _F ) of the transient response voltage V _S1 of the terminal S1 and the terminal S2 becomes smaller than the time constant (L2 / R _F ) of the transient response voltage V _S2 . falling and for the pulse power of the transient response voltage V _S1 shown in rise is faster with respect to the transient response voltage V _S2.

When the core 13 is displaced to the X1 side, the detection voltage V _D (= V _S1 −V _S2 ) across the detection terminals S1 and S2 becomes
The falling period of the pulse power supply is detected with a minus (-) polarity, and the rising period of the pulse power supply is detected with a plus (+) polarity. When the core 13 of the displacement sensor 11 in FIG. 2 is displaced to the X2 side, the detection voltage V _D (= V _S1 −V _S2 ) has the opposite relationship to the above, and the falling period of the pulse power supply is positive. (+), The rising period of the pulse power supply is detected as minus (-).

[0043] Thus, the detection voltage V _D (= V _S1 -
V _S2 ), the displacement of X1 and X2 and the detection voltage V
_The direction of displacement can be detected by the sign of _D.

In FIG . 4, if the detection voltage V _D is detected in the falling period of the pulse power supply, the detection voltage V _D (= sign is minus) having the maximum absolute value (sign is minus) at time t _M in FIG. V _DMAX-) can be detected, it can be detected to detect the voltage V _D at time T1 in (b) FIG. It should be _noted that by setting the time T1 to t _M in the diagram (b), the same detection voltage V _D (= V _DMAX− ) as in the diagram (a) can be detected.

Further, in FIG. 5A, the detection voltage V _D can be detected during the rising period of the pulse power supply, and the detection voltage V _D having the maximum absolute value (the sign is plus) can be obtained.
_D (= V _{DMAX +} ) can be detected.

[0046] Thus, even in the amount of displacement is the same of the displacement sensor 11, by setting to detect the maximum value of the detection voltage V _D, constituting a displacement detector 10 sensitive.

FIG . 5 is an overall block diagram of the displacement detector according to the first to third aspects including the deviation voltage detecting means. In FIG. 5, a displacement detector 10 includes a displacement sensor 11, a pulse power supply 15, and a deviation voltage detecting means 16, and a detection terminal S
1, the detection voltage across S2 V _D and the pulse information V _I from the terminal Po of the pulsed power supply 15 (e.g., rising, falling information, the peak value V _I information) the difference voltage detection unit based on 16
There detects the maximum value of the detection voltage V _D (V _DMAX- or V _{DMAX +),} and converts the corresponding to the displacement amount X in the detection voltage V _D configured to output.

[0048] FIG. 6 is a schematic block diagram of the difference voltage detection means of the displacement detector according to claim 1. The deviation voltage detecting means 16 is basically composed of a microprocessor and includes a deviation voltage storing means 16A, a falling pulse detecting means 16B, a timer means 16C, a maximum deviation voltage calculating means 17, a displacement amount converting means 18, and the displacement sensor 11 Detected voltage V
Calculates the maximum deviation voltage V _DMAX- in the falling period of the pulsed power supply 15 based on _D, the displacement X of the maximum deviation voltage V _DMAX-
And output it.

The deviation voltage storage means 16A is an A / D converter,
Differential amplifier, comprising a memory and a switching circuit such as a rewritable RAM, the detection voltage V _D of the displacement sensor 11 detects
The falling pulse detecting means fall information T _D provided from 16B, the pulse power source 15 based on the rising information T _U falling period (peak value V _I) (time T / 2 in FIG. 4 or time T1,) And stores it as a digital value. Incorporation number of the detection voltage V _D is configured, for example as performed at the timing of the sampling pulse generated by the control of the microprocessor.

The deviation voltage storage means 16A operates the pulse power supply 15 (peak value V _I ) by the switching operation of the switching circuit.
Falling during the period stores the detection voltage V _D in the memory of, together during the rising period to control so as not to store the detection voltage V _D in the memory, the detection voltage V _D after receiving the rising information T _U is stored in the memory _Are sequentially output to the maximum deviation voltage calculating means 17.

The maximum deviation voltage calculation means 17 is composed of a comparator, a memory for storing the maximum value, and the like. The maximum deviation voltage calculation means 17 compares the detection voltage data V _DM sequentially supplied from the deviation voltage storage means 16A and calculates a larger detection voltage data V _DM. by storing, providing a maximum deviation voltage V _DMAX- the displacement conversion means 18 as the maximum value of the detected voltage data V _DM.

[0052] falling pulse detecting means 16B is falling and the rising of the pulse power supply 15 (e.g., an edge) is detected, outputs the falling information T _D and the rising information T _U to the deviation voltage storing means 16A and the timer means 16C I do. Timer means 16C starts counting based on the falling information T _D, stops counting at the rising information T _U, to provide a timer signal T _K which is timed to the displacement amount conversion unit 18.

The displacement amount converting means 18 has a memory such as a ROM, and stores data of a maximum deviation voltage V _DMAX- set in advance based on a theoretical value (computed value) or an experimental value and data of a corresponding displacement amount X. The displacement signal X corresponding to the maximum deviation voltage _VDMAX- from the maximum deviation voltage calculation means 17 is output.

[0054] Also, the sign of the maximum difference voltage V _DMAX-, displacement converting means 18 is previously stored in a memory such as a falling period T _DO of the rewritable RAM of the pulsed power supply 15 to be used, the timer means When the timer signal T _K supplied from 16C is equal to the falling period T _DO, it is detected by adding the minus (−) sign information to the displacement amount signal X and outputting it. However, in the case of this configuration, the falling period and the rising period of the pulse power supply shown in FIG. 4A are set to different values so that the falling period or the rising period of the pulse power supply 15 can be distinguished.

The detection voltage data _VDM is configured to include digital information of magnitude (voltage value) and sign.
Digital code information may be included in the displacement signal X and output.

[0056] In addition, the difference voltage detection unit 16 corresponding to the (b) figure 4, remove the maximum deviation voltage calculation unit 17 and the timer means 16C, based on the rising information T _U falling pulse detecting means 16B the amount of displacement deviation voltage storing means 16A sends the difference voltage V _D directly displacement converting means detected voltage data V _DM stores 18, corresponding to the detected voltage data V _DM previously set in the ROM of the displacement conversion means 18 It can be configured to output X.

[0057] Thus, the difference voltage detection unit 16 of the displacement detector according to claim 1, stores the detected voltage V _D of the displacement sensor 11 during the falling period of the pulsed power supply 15 is detected,
The stored based on the detection voltage V _D detects the maximum value as the maximum difference voltage V _DMAX-, a displacement signal X corresponding to the maximum difference voltage V _DMAX- since outputs with the code, the magnitude of displacement with high sensitivity In addition to the detection, the displacement direction can be detected.

FIG . 7 is a block diagram of a main part of the deviation voltage detecting means of the displacement detector according to the second aspect . 7, the deviation voltage detecting means 21 is basically composed of a microprocessor, and includes a deviation voltage storing means 22, a falling / rising pulse detecting means 23, a falling deviation voltage detecting means 24, a rising deviation voltage detecting means 25, and a deviation output. Means 26, a cycle detecting means 27, and a displacement converting means 18, and the maximum deviation voltage V _DMAX- during the falling period of the pulse power supply 15 of the detection voltage V _D detected by the displacement sensor 11 and the maximum deviation voltage during the rising period, respectively. After detecting the deviation voltage V _{DMAX +} , and further detecting the deviation between the maximum deviation voltage V _DMAX- and the maximum deviation voltage V _{DMAX +} as the deviation output V _DO , the deviation output V _DO is used as a corresponding displacement amount signal X.
_{It is} configured to convert to _O and output.

The deviation voltage storage means 22 includes an A / D converter, a differential amplifier, a memory such as a rewritable RAM, a switching circuit, and the like, similarly to the deviation voltage storage means 16A of FIG.
The detection voltage V _D detected by the displacement sensor 11 falls, and the falling information T _D provided from the rising pulse detecting means 23,
Pulse power supply 15 based on the rising information T _U (peak value V _I)
(T / 2 or T1 in FIG. 4) and the rising period (T / 2 to T) in FIG. 4 (a) are taken in a predetermined number of times, and the detection voltages in the falling period and the rising period are respectively taken. the V _D is stored in memory in a digital value.

The deviation voltage storage 22 stores the detected voltage data V _DM− and V _{DM +} of the detected voltage V _D stored in the memory during the falling period and the rising period, respectively, into the falling deviation voltage detecting unit 24 and the rising deviation. The voltage is supplied to the voltage detecting means 25.

The falling deviation voltage detecting means 24 and the rising deviation voltage detecting means 25 each comprise a comparator, a memory for storing the maximum value, etc., and fall information T _D provided from the falling and rising pulse detecting means 23. , rising information T _U detected voltage data is provided from the deviation voltage storing means 22 as a trigger V _DM-, sequentially comparing calculated by captures and V _{DM +,} stores larger detection voltage data V _DM-, the V _{DM +} Thus, the maximum deviation voltage V _DMAX- and the maximum deviation voltage V _{DMAX +} are provided to the deviation output means 26.

The deviation output means 26 is composed of a comparison circuit such as an operational amplifier.
4A based on the periodic signal T _S corresponding to the cycle of FIG.
The maximum deviation voltage V for one cycle (time T) of the pulse shown in the figure
_The deviation between _DMAX- and the maximum deviation voltage _{VDMAX +} (= _VDMAX- -V
_{DMAX +} ), and outputs the deviation output V _DO to the displacement conversion means 18.
To supply. Since the maximum deviation voltage V _DMAX− and the maximum deviation voltage V _{DMAX +} have different signs, if the absolute values of V _DMAX− and V _{DMAX +} are equal, the deviation output V _DO will be the maximum deviation voltage V _DMAX− or the maximum deviation. It can be detected at twice the value of the voltage V _{DMAX +} .

[0063] displacement converting means 18 in the same configuration as that shown in FIG. 6, the theoretical value (calculated value) or deviation set in advance based on experimental values output _{V DO (= V DMAX- -V DMAX} +), the corresponding Is stored, and the displacement X _O corresponding to the deviation output V _DO supplied from the deviation output means 26 is stored.
Is output.

[0064] period detecting means 27 is constituted by a timer circuit or the like, falling, detecting a pulse period T of the pulsed power supply 15 on the basis of falling information T _D from the rising edge detection unit 23, the rising information T _U, periodic signal T _S is output to the deviation output means 26.

[0065] Thus, the displacement detector of the difference voltage detection unit 21 according to the second aspect, during the falling period and during the rise time of the pulsed power supply 15, the detection voltage V, each displacement sensor 11 detects _DM-, V _{DM +} , and the detected voltages V _DM− , stored during the falling period and the rising period, respectively.
The maximum value of V _{DM +} is determined by the maximum deviation voltage V _DMAX- and the maximum deviation voltage V
_{DMAX +} detected as calculates the maximum deviation voltage V _DMAX- and the maximum difference voltage V _{DMAX +} deviation a deviation output V _DO, since outputs a displacement signal X _O corresponding to the differential output V _DO, the size of the displacement Can be detected with higher sensitivity.

[0066] Further, the direction of the displacement is set based on the sign of the differential output V _DO, for example, sign minus (-) if made to correspond to X1 direction in FIG. 2, reference numeral plus (+) if the 2 It can correspond to the X2 direction.

Although the core of the displacement sensor is made of a non-magnetic material in the above embodiment, it may be made of a magnetic material.

The deviation voltage detecting means converts the deviation (detection voltage V _D ) of the analog transient response voltage detected by the displacement sensor into a digital value by an A / D converter, and processes the deviation. Can be processed as an analog value. FIG. 8 is a block diagram showing an embodiment of a deviation voltage detecting means constituted by an analog circuit.

In FIG . 8, the deviation voltage detecting means 31
Bottom hold circuit 32 the voltage value at time T ₁ of the transient response voltage V _S1, V _S2 falling period respectively detected by the displacement sensor 11 (shown in FIG. 4 (b) see figure) to (bottom voltage) held by an analog value And 33 and the bottom voltages V _D1 and V _D from the bottom hold circuits 32 and 33, respectively.
_D2 deviation of (V _D1 -V _D2) was amplified by calculation, to a comparator circuit 33 for outputting a displacement signal X.

Since the deviation voltage detecting means 31 is constituted by an analog circuit, it detects the displacement from the absolute value of the displacement signal X and the displacement direction from the sign (plus or minus) of the displacement signal X.

[0071] Next, an embodiment which applies the displacement detector to the torque detector. FIG. 9 is a block diagram of a main part of a torque detector to which the displacement detector according to the present invention is applied, and FIG. 10 is a waveform diagram of each functional part of the torque detector. In FIG. 9, the torque detector 40 includes a torque sensor 41 to which a displacement detector is applied and a torque detecting means 46.

The torque sensor 41 includes an input shaft 42, an output shaft 43, a torsion bar (not shown) connecting the input shaft 42 and the output shaft 43, a core 44 constituting a displacement sensor, a coil 45A, a coil 45B and a not-shown 2 The reference resistors are provided.

When a torque (T) acts on the input shaft 42 and the output shaft 43, a torsion bar generates a torsion angle (θ _T ) proportional to the torque (T).
The torsion angle (θ _T ) is determined by the action of the pins connected to the shafts and the spiral grooves and longitudinal grooves (both not shown) provided in the core 44, and the core 44 in the axial direction of the shaft.
(X _T ).

[0074] displacement of the core 44 (x _T), the coil 45A already described, inductance change of the coil 45B (delta
L _T ), and the inductance change (ΔL _T ) is detected as the transient response voltages V _S1 and V _S2 of the pulse voltage V _I applied to the bridge circuit composed of the coils 45A and 45B and two reference resistors. I do.

[0075] Thus, by constituting the torque sensor 41 with a displacement sensor displacement detector according to the present invention, converted to a torque angle torsionally _(T) (θ T), the twist angle (theta _T) Since it can be converted to the displacement (x _T ) of the core 44,
From this displacement (x _T ), it is detected as a change in inductance (ΔL _T ) of the corresponding coil, and the change in inductance (ΔT
L _T) can be detected as a corresponding pulse transient response voltage V _S1, V _S2 and.

The torque detecting means 46 includes a torque sensor 41
To a pulse generating circuit 51 supplies a pulse voltage V _I, the pulse transient response voltage V _S1 detected by the torque sensor 41, V
First-order CR low-pass filters 47A and 47B for outputting pulse transient response voltage Va (V _S1 , V _S2 ) by removing high-frequency switching noise (N _S ) included in _S2 , and pulse transient response voltage Va (V _S1 , V _S2 ), the bottom voltage V _T1 ,
Bottom hold circuit 48A, 4 to output to hold the V _T2
Deviation and 8B, the bottom voltage V _T2 and the bottom voltage V _T1 (V
_T2− V _T1 ), amplifies by the gain G1, and outputs the deviation voltage Vb, and the torque detection voltage V obtained by inverting the deviation voltage Vb and shifting the reference voltage (for example, 2.5V). _And an inverting amplifier 50 for detecting _T.

[0077] Thus, the torque detection means 46, and configured to detect a value corresponding to the torque (T) (absolute values and direction) acting on the torque sensor 41 with the absolute value of the torque detection voltage V _T, e.g. decreasing the torque detection voltage V _T when the torque (T) is applied to the left, setting the characteristic represented by the straight line shown in (f) diagram of Figure 10 such that the torque detection voltage V _T increases to act in the right direction I do.

[0078] Thus, by storing a conversion table of pre-designed values and torque obtained based on the experimental value (T) and the torque detection voltage V _T as data in a memory such as a ROM, a torque detection means 46 detects Torque detection voltage V _T
The torque (T) acting on the torque sensor 41 can be detected based on the (absolute value).

FIG . 10 shows waveforms of functional blocks of the torque detecting means 46. (A) drawing the pulse voltage V _I output waveform of the pulse generating circuit 51, (b) drawing a pulse transient response voltage V _S1, V _S2 waveform detected by the bridge circuit of the torque sensor 41, the pulse voltage V _I stand the output circuit 51B of the pulse generating circuit 51 in the down and rising (for example, switching transistors) includes switching noise N _S of.

[0080] (c) drawing the low-pass filter 47A, 47
It is a pulse transient response voltage Va (V _S1 , V _S2 ) waveform that has passed through B, and the switching noise N _S is removed.
(D) drawing represent a bottom voltage V _T1 and the bottom voltage V _T2 waveform, (e) drawing the deviation voltage V obtained by amplifying the deviation of the bottom voltage V _T2 and the bottom voltage V _T1 to (V _T2 -V _T1) only the gain G1
The b waveform is shown.

[0081] (f) drawing the reference voltage by inverting the difference voltage Vb (e.g., 2.5V) is only the torque detection voltage V _T waveform is shifted, the torque detection voltage when the torque (T) is 0 V _T is reference voltage (2.5V), torque (T)
It changes linearly according to the direction and size of.

Although the torque detecting means 46 is constituted by an analog circuit in the embodiment, it may be constituted by a digital circuit. In addition, calculation using a microprocessor,
The processing such as the determination may be configured by software.

[0083]

As described above, the displacement detector according to the present invention includes a displaceable core, a detection coil whose inductance changes in accordance with the amount of displacement of the core, and a reference resistor. By detecting the transient response voltage corresponding to the inductance and the reference resistance, the absolute value of the inductance can be detected, and the change in the inductance with respect to the displacement of the core can be detected independently of the peak value and frequency of the pulse power supply. The displacement of the core can be accurately detected.

Further, the displacement detector according to the present invention comprises a displaceable core, two detection coils whose inductance changes differentially in accordance with the displacement of the core, two reference resistors, and a deviation voltage detecting means. A bridge circuit is configured with two detection coils and two reference resistors, a pulse power supply is applied to the bridge circuit, a transient response voltage of the bridge circuit output is detected, and a deviation voltage of the transient response voltage is deviated. Since the voltage detection means can detect the differential change of the inductance with respect to the displacement of the core by the transient response voltage, the displacement of the core can be detected with high sensitivity.

[0085] Furthermore, the difference voltage detection means of the displacement detector according to the present invention, the maximum deviation voltage calculating means for detecting a maximum value of the deviation of the transient response voltage, the amount of displacement the maximum deviation voltage from maximum deviation voltage calculating means And a displacement amount conversion means for converting the displacement into a large value, and the displacement amount can be detected with a large voltage value, so that a highly sensitive displacement detector can be realized.

Further , the deviation voltage detecting means of the displacement detector according to the present invention includes a falling maximum deviation voltage detecting means, a rising maximum deviation voltage detecting means, a deviation output means, and a displacement amount converting means. Since the maximum value of the deviation of the transient response voltage at the time of the rise is detected, and the deviation of each maximum value is detected and converted into a displacement amount, the displacement amount can be detected with a larger voltage value. A displacement detector with high sensitivity can be realized.

[0087] Thus, it is possible to provide a displacement detector capable of detecting the displacement amount with high accuracy and high sensitivity.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a displacement detector.

FIG. 2 is a configuration diagram of a displacement detector according to claims 1 to 3;

FIG. 3 is a configuration diagram of an embodiment of a displacement sensor.

FIG. 4 is a transient response voltage waveform diagram of the displacement detector according to claims 1 to 3;

FIG. 5 is an overall block configuration diagram including a deviation voltage detecting means of the displacement detector according to claims 1 to 3;

FIG. 6 is a block diagram of a main part of a deviation voltage detecting means of the displacement detector according to claim 1 .

FIG. 7 is a block diagram of a main part of a deviation voltage detecting means of the displacement detector according to claim 2;

FIG. 8 is a block diagram showing an embodiment of a deviation voltage detecting means constituted by an analog circuit;

FIG. 9 is a block diagram of a main part of a torque detector to which the displacement detector according to the present invention is applied.

FIG. 10 is a waveform diagram of each functional unit of the torque detector.

FIG. 11 is a configuration diagram of a main part of a conventional displacement detector.

[Explanation of symbols]

1,10 ... displacement detector, 2,12A, 12B, 45A,
45B: detection coil, 3, 13, 44: core, 5, 15
... Pulse power supply, 11 ... Displacement sensor, 14 ... Bridge circuit, 16, 21, 31 ... Deviation voltage detecting means, 16A, 2
2: Deviation voltage storage means, 16B: Falling pulse detection means, 16C: Timer means, 17: Maximum deviation voltage calculation means, 18: Displacement amount conversion means, 23: Falling and rising pulse detecting means, 24: Falling deviation Voltage detection means, 25: rising deviation voltage detection means, 26: deviation output means, 27: cycle detection means, 32, 33, 48A, 48B: bottom hold circuit, 33: comparison circuit, 40: torque detector, 41
... torque sensor, 46 ... torque detecting means, L, L1, L
2 ... inductance, R _F ... reference resistance, T _D ... falling information, T _S ... period signal, T _U ... rise information, V _I ... pulse power peak value, V _D ... detection voltage, V _DM, V _DM-, V _{DM +} ... detection voltage data, V _DMAX-, V _{DMAX +} ... maximum deviation voltage, V _DO ...
Differential _{output, V O, V O1, V} S1, V S2 ... transient response voltage, X
1, X2 ... displacement, X, _Xo ... displacement amount signal.

────────────────────────────────────────────────── ─── Continued on the front page Examiner Mitsuo Shiraishi (56) References JP-A-60-253920 (JP, A) JP-A-2-193002 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) G01B 7/00

Claims (3)

(57) [Claims] 1. A core displaceable in both directions from a neutral position.
And symmetrically arranged in the direction of displacement of the core from the neutral position.
And the inductance changes differentially according to the core displacement
Two detection coils and those of these two detection coils
Two reference resistors connected in series with each other, and these two
A bridge consisting of a reference resistor and the two detection coils
Circuit, a pulse power supply applied to the bridge circuit,
Both ends of each of the two reference resistors of the bridge circuit
Voltage detection means for detecting the deviation voltage of the transient response voltage
And a displacement amount and a displacement direction of the core based on the deviation voltage.
And the deviation voltage detecting means detects the two bases.
The maximum value of the deviation of the transient response voltage across
Means for calculating the maximum deviation voltage to be detected;
The maximum deviation voltage from the calculation means into the displacement
Displacement detector, characterized in that a switch means. 2. A core displaceable in both directions from a neutral position.
And symmetrically arranged in the direction of displacement of the core from the neutral position.
And the inductance changes differentially according to the core displacement
Two detection coils and those of these two detection coils
Two reference resistors connected in series with each other, and these two
A bridge consisting of a reference resistor and the two detection coils
Circuit, a pulse power supply applied to the bridge circuit,
Both ends of each of the two reference resistors of the bridge circuit
Voltage detection means for detecting the deviation voltage of the transient response voltage
With the door, the difference voltage detection means, wherein each of the two reference resistors
The maximum value of the deviation of the falling transient response voltage across the
A falling maximum deviation voltage detecting means, and the two reference resistors and
Detect the maximum value of the deviation of the rising transient response voltage at both ends.
Output rising maximum deviation voltage detecting means;
The output from the deviation voltage detecting means and the rising maximum deviation voltage
Deviation output that outputs the maximum deviation from the output from the detection means
Means and displacement amount conversion for converting the maximum value deviation into a displacement amount
Displacement detector, characterized in that a means. 3. A core displaceable in both directions from a neutral position.
And symmetrically arranged in the direction of displacement of the core from the neutral position.
And the inductance changes differentially according to the core displacement
Two detection coils and those of these two detection coils
Two reference resistors connected in series with each other, and these two
A bridge consisting of a reference resistor and the two detection coils
Circuit, a pulse power supply applied to the bridge circuit,
Both ends of each of the two reference resistors of the bridge circuit
Voltage detection means for detecting the deviation voltage of the transient response voltage
With the door, der less time constant period falling waveform of the pulse power supply
That the transient response voltage does not become 0V.
Characterized displacement detector.