JPH07218210A - Non-contact displacement measuring circuit - Google Patents

Abstract

PURPOSE:To enable detection of an elongation difference between a ground section of a turbine wheel chamber and a turbine rotor accurately when the action of an assumed secondary circuit generated in a flange of a wheel shaft increases with an increase in the number of revolutions of the turbine rotor. CONSTITUTION:While the number of revolutions is detected with a number of revolutions detecting circuit 8, first and second displacement detectors 3 and 4 and an AC bridge circuit 5 are driven with an AC power source circuit 2 for excitation to generate an AC signal according to an elongation difference between a ground section of a turbine wheel chamber and the turbine rotor. A transformer circuit 7 is driven with a synchronous rectifier circuit 6 to perform a synchronous rectification of the AC signal generated with the AC bridge circuit 5. Then, a voltage signal obtained by the synchronous rectifying operation with a signal processing circuit 9 is corrected based on the results in the detection with the number of revolutions detection circuit 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine monitoring device for monitoring a turbine generator installed in a power plant or the like, and particularly to a non-contact displacement measuring relative displacement between an axle and a casing of the turbine generator. Regarding measurement circuits.

[0002]

2. Description of the Related Art A turbine generator installed in a thermal power plant or the like generates electric power by rotating a turbine at high speed with steam and rotating a generator connected to the turbine.

In this case, in a normal turbine, a turbine rotor is arranged in the turbine casing and high temperature steam is introduced into the turbine casing to rotate the turbine rotor.
Electricity is obtained by rotating a generator connected to this turbine rotor.

In order to increase the power generation efficiency of the turbine generator, in a normal turbine, the tips of the blades provided on the turbine rotor and the ground portion of the turbine casing are attached at a very narrow interval.

Therefore, when high-temperature steam is applied to the turbine, the turbine casing and the turbine rotor are expanded due to the high-temperature steam and the centrifugal force generated by the rotation of the turbine rotor, but these expansions are not uniform. ,
These expansion differences are measured by a movement amount measuring and monitoring system using an inductance type displacement gauge or the like so that the blades and the ground portion do not come into contact with each other.

FIG. 3 is a block diagram showing an example of a non-contact displacement measuring circuit used in such a movement amount measuring and monitoring system.

The non-contact displacement measuring circuit 101 shown in this figure includes an exciting AC power supply circuit 102 and a first displacement detector 103.
, The second displacement detector 104, and the AC bridge circuit 105
, Synchronous rectification circuit 106, transformer circuit 107, V
An I / I conversion circuit 108 and an output generation circuit 109 are provided, and the excitation AC power supply circuit 102 drives the first and second displacement detectors 103 and 104 and the AC bridge circuit 105 to drive the turbine casing. While generating an AC voltage according to the expansion difference between the ground part and the turbine rotor,
After the synchronous rectification circuit 106 drives the transformer circuit 107 to synchronously rectify the AC signal generated by the AC bridge circuit 105, the V / I conversion circuit 108 converts the voltage signal obtained by the synchronous rectification operation into V / I. After being converted into a current signal, the output signal is converted into a plurality of signals by the output generation circuit 109 and output.

In the exciting AC power supply circuit 102, the ground terminal is connected to the midpoint of the primary coil 110a of the transformer 110 constituting the transformer circuit 107, and the power supply output terminal constitutes the first displacement detector 103. Coil 11
1 is a power supply circuit connected to one end of the first displacement coil 104, one end of the coil 112 configuring the second displacement detector 104, and one end of the resistor 113 configuring the AC bridge circuit 105, and takes in an AC voltage supplied from a commercial power source. An AC voltage having a voltage value designated in advance is generated and is supplied to the first displacement detector 103, the second displacement detector 104, and the AC bridge circuit 105.

The first displacement detector 103 is an iron core 116 having a "U" -shaped vertical section, which is arranged at a position facing the first surface of a flange 115 attached to an axle 114 of a turbine rotor in a turbine casing. The iron core 116 is wound around, one end is connected to the power output terminal of the exciting AC power supply circuit 102, and the other end is connected to the AC bridge circuit 105.
Coil 111 connected to one end of a resistor 117 forming
And an inductance corresponding to the displacement of the axle 114 of the turbine rotor with respect to the turbine casing, and when the AC voltage supplied from the excitation AC power supply circuit 102 excites the inductance, Generated voltage, which is generated by the AC bridge circuit 105.
Supply to.

The second displacement detector 104 is an iron core 118 having a U-shaped vertical cross section, which is arranged at a position facing the second surface of the flange 115 in the turbine casing, and the iron core 1
18 winding, one end of which is the exciting AC power supply circuit 102
Of the axle 114 of the turbine rotor, which is connected to the power output terminal of the turbine rotor and has the other end connected to one end of the resistor 119 forming the AC bridge circuit 105. The inductance corresponds to the displacement, and when excited by the AC voltage supplied from the exciting AC power supply circuit 102, a voltage corresponding to the inductance is generated and supplied to the AC bridge circuit 105.

The AC bridge circuit 105 has a bridge-forming resistor 113, one end of which is connected to the power output terminal of the exciting AC power supply circuit 102, and the other end of the coil 111, which constitutes the first displacement detector 103. And a resistor 117 for bridge configuration connected to the other end, a resistor 119 for bridge configuration whose one end is connected to the other end of the coil 112 that constitutes the second displacement detector 104, and a resistor 117 for the first terminal.
A balance adjustment variable resistor 120 connected to the other end of the resistor 119, a second terminal connected to the other end of the resistor 119, and a sliding terminal connected to the other end of the resistor 113. A bridge is configured by the first and second displacement detectors 103 and 104, the resistors 113, 117 and 119, and the variable resistor 120, and the first AC voltage for excitation output from the AC power supply circuit 102 for excitation causes the first voltage When the second displacement detectors 103 and 104 are excited, an AC voltage corresponding to the impedances of the first and second displacement detectors 103 and 104 is generated, and the AC voltage is generated by the transformer circuit 10.
7 is supplied to each terminal of the primary coil 110a of the transformer 110.

Further, the synchronous rectification circuit 106 has a ground terminal grounded and has a first synchronous rectification AC power supply 121 for generating an AC voltage having a preset frequency, voltage value and phase, and one end for the first synchronous rectification. A resistor 122 connected to a power supply output terminal of the AC power supply 121, a second AC power supply 123 for synchronous rectification, whose ground terminal is grounded, and which generates an AC voltage having a preset frequency, voltage value, and phase, and one end of which is described above. Second
A resistor 124 connected to the power output terminal of the AC power supply 123 for synchronous rectification, four diodes 125 to 128, and four resistors 129 to 132 are provided, and the AC voltage supplied via the resistors 122 and 124 is used. Bridge circuit 133 that generates an excitation voltage for synchronous rectification based on
It has and.

The first and second AC power supplies 1 for synchronous rectification
21, 123 generate an AC voltage for synchronous rectification corresponding to the phase, frequency and voltage value of the AC voltage output from the exciting AC power supply circuit 102, and the bridge circuit 133 excites the AC voltage based on the AC voltage. A voltage is generated and supplied to one end of each of the resistors 134 and 135 that form the transformer circuit 107.

The transformer circuit 107 includes a primary coil 110a.
Is connected to the first and second terminals of the variable resistor 120 that constitutes the AC bridge circuit 105, the middle point is connected to the ground terminal of the exciting AC power supply circuit 102, and one end is 2 connected to the first output terminal of the bridge circuit 133 and the other end of which constitutes the transformer 110
A resistor 134 connected to one end of the secondary coil 110b and a secondary coil 1 having one end connected to the second output terminal of the bridge circuit 133 and the other end constituting the transformer 110.
It has a resistor 135 connected to the other end of 10b, and a capacitor 136 having one end connected to one end of the resistor 134 and the other end connected to one end of the resistor 135.

The primary coil 11 of the transformer 110
0a receives the AC voltage output from the AC bridge circuit 105, and the resistors 134 and 135 receive the excitation voltage for synchronous rectification output from the synchronous rectification circuit 106, thereby receiving the secondary coil 1 of the transformer 110.
10b is excited, whereby the AC bridge circuit 1 is excited.
A differential voltage of the AC voltage output from the output terminal 05 is generated, which is taken out from the midpoint of the secondary coil 110b and supplied to the V / I conversion circuit 108.

The V / I conversion circuit 108 is a circuit in which the ground terminal is grounded and the signal input terminal is connected to the midpoint of the secondary coil 110b constituting the transformer 110, and the secondary coil 110b of the transformer 110 is connected. The difference voltage (voltage signal) output from the midpoint is taken in, the voltage signal is V / I converted into a current signal, and this is supplied to the output generation circuit 109.

One end of the output generation circuit 109 has an output terminal 13
A resistor 138 that is connected to 7 and is grounded, and one end of which is connected to the output terminal 139
A resistor 140 connected to the other end of the resistor 38, a constant voltage whose anode is connected to the other end of the resistor 140 and the output terminal 141, and whose cathode is connected to the output terminal and the output terminal 143 of the V / I conversion circuit 108. And a diode 142, which takes in a current signal output from the V / I conversion circuit 108, generates a plurality of signals based on the current signal, and outputs the plurality of signals to the output terminals 137 and 13 respectively.
It outputs from 9, 141, and 143.

[0018]

By the way, in such a conventional non-contact displacement measuring circuit 101, the coil 111 and the second coil of the first displacement detector 103 and the second electrode are detected by the AC voltage obtained by the exciting AC power supply circuit 102. By exciting the coil 112 of the displacement detector 104, these first and second
Since the impedances of the displacement detectors 103 and 104 are converted into electric signals, virtual secondary circuits 144 and 145 are formed on the flange 115 of the turbine rotor, and the virtual secondary circuits 144 and 145 make the first , The impedance due to the main magnetic flux from the second displacement detectors 103 and 104 decreases.

Then, as the rotational speed of the turbine rotor increases, the action of the virtual secondary circuits 144, 145 formed on the flange 115 increases, and the first and second
Since the impedance due to the main magnetic flux from the displacement detectors 103 and 104 is greatly reduced, when the rotation speed of the turbine rotor is low, the ground portion of the turbine casing is
Although the expansion difference from the turbine rotor can be detected almost accurately, there is a problem that the detection error becomes large when the rotational speed of the turbine rotor becomes high.

In view of the above-mentioned circumstances, the present invention takes into consideration the above circumstances, even if the rotation speed of the turbine rotor is increased and the action of the virtual secondary circuit generated on the flange of the axle is increased, the gland portion of the turbine casing and the turbine rotor are also provided. It is an object of the present invention to provide a non-contact displacement measuring circuit capable of accurately detecting the difference in elongation between and.

[0021]

In order to achieve the above-mentioned object, the present invention provides a moving amount of an object to be measured by generating an AC voltage for excitation by an AC power supply circuit for excitation according to claim 1. The two coils whose inductance changes according to the above, the AC bridge circuit extracts the difference signal of the electric signal corresponding to the impedance of each coil, and the synchronous rectification AC power supply circuit synchronously excites the transformer circuit. In a non-contact displacement measuring circuit that synchronously rectifies the difference signal and generates a DC voltage signal, a rotation speed detection circuit that detects the rotation speed of the object to be measured and generates a rotation speed signal, and the rotation speed detection circuit. A signal processing circuit for correcting the rotational speed of the synchronously rectified DC voltage signal output from the transformer circuit based on the rotational speed of the object obtained by a circuit. It is characterized by comprising a.

Further, in the present invention, an exciting AC power supply circuit generates an exciting AC voltage to excite two coils whose inductance changes according to the amount of movement of an object to be measured, and an AC bridge. A contactless circuit that extracts a difference signal of an electric signal according to the impedance of each coil by a circuit and synchronously rectifies the difference signal by synchronously exciting a transformer circuit by an AC power supply circuit for synchronous rectification to generate a DC voltage signal. In the displacement measuring circuit, a resistance value detection circuit that calculates a DC resistance value of each coil by measuring a value of a current flowing through each coil and a voltage across each coil, and each obtained by the resistance value detection circuit. The temperature of each coil is calculated based on the DC resistance value of the coil, and the synchronous rectification output from the transformer circuit is performed based on the calculation result. It is characterized in that a signal processing circuit for temperature compensation of Mino DC voltage signal.

[0023]

In the above structure, in the first aspect, the rotation speed detection circuit detects the rotation speed of the object to be measured to generate the rotation speed signal, and the signal processing circuit obtains the rotation speed detection circuit. Based on the obtained rotational speed of the object, the synchronously rectified DC voltage signal output from the transformer circuit is rotational speed corrected.

According to the present invention, the resistance value detection circuit measures the value of the current flowing through each coil and the voltage across each coil to calculate the DC resistance value of each coil. Based on the DC resistance value of each coil obtained by the resistance value detection circuit, the temperature of each coil is calculated, and the DC voltage signal of the synchronous rectified output from the transformer circuit is temperature-corrected based on the calculation result. It

[0025]

1 is a block diagram showing an embodiment of a non-contact displacement measuring circuit according to the present invention.

The non-contact displacement measuring circuit 1 shown in this figure includes an exciting AC power supply circuit 2, a first displacement detector 3, a second displacement detector 4, an AC bridge circuit 5, a synchronous rectification circuit 6,
The transformer circuit 7, the rotation speed detection circuit 8, the signal processing circuit 9, the V / I conversion circuit 10, and the output generation circuit 11 are provided, and the rotation speed detection circuit 8 detects the rotation speed of the turbine rotor. Meanwhile, the excitation AC power supply circuit 2 drives the first and second displacement detectors 3 and 4 and the AC bridge circuit 5 to drive an AC signal corresponding to the difference in expansion between the ground portion of the turbine casing and the turbine rotor. And generate
After the transformer circuit 7 is driven by the synchronous rectification circuit 6 to synchronously rectify the AC signal generated by the AC bridge circuit 5, the signal processing circuit 9 performs the synchronous rectification on the basis of the detection result of the rotation speed detection circuit 8. The voltage signal obtained by the operation is corrected, and this is corrected by the V / I conversion circuit 10
After the V / I conversion is performed to convert the current signal into a current signal, the output generation circuit 11 converts the current signal into a plurality of signals and outputs the signals.

In the exciting AC power supply circuit 2, the grounding terminal of the transformer 12 constitutes the primary coil 12 of the transformer 12.
While being connected to the midpoint of a, the power supply output terminal connects one end of the coil 13 configuring the first displacement detector 3 and one end of the coil 14 configuring the second displacement detector 4 to the AC bridge circuit 5. It is a power supply circuit connected to one end of the resistor 17 that composes, takes in an AC voltage supplied from a commercial power supply, and generates an AC voltage having a predetermined voltage value.
This is the AC bridge circuit 5 and the first displacement detector 3
And the second displacement detector 4.

The first displacement detector 3 is arranged in a position facing the first surface of the flange 18 provided on the axle of the turbine rotor in the turbine casing, and the iron core 15 has a U-shaped cross section.
A coil 13 wound around the iron core 15 and having one end connected to the power output terminal of the exciting AC power supply circuit 2 and the other end connected to one end of a resistor 19 forming the AC bridge circuit 5. And has an inductance according to the displacement of the axle of the turbine rotor with respect to the turbine casing, and when the magnet is excited by the AC voltage supplied from the exciting AC power supply circuit 2, the inductance is satisfied. A voltage is generated and supplied to the AC bridge circuit 5.

The second displacement detector 4 is provided with an iron core 16 having a U-shaped vertical cross section, which is arranged at a position facing the second surface of the flange 18 in the turbine casing, and is wound around the iron core 16. And a coil 14 having one end connected to the power supply output terminal of the excitation AC power supply circuit 2 and the other end connected to one end of a resistor 20 forming the AC bridge circuit 5. The inductance becomes an inductance according to the displacement of the axle of the turbine rotor with respect to the chamber, and when excited by the AC voltage supplied from the exciting AC power supply circuit 2, a voltage corresponding to the inductance is generated to generate the voltage. Supply to the AC bridge circuit 5.

The AC bridge circuit 5 has a bridge-forming resistor 17 having one end connected to the power output terminal of the exciting AC power supply circuit 2, and the other end of the coil 13 forming one end of the first displacement detector 3. And a resistor 19 for bridge configuration connected to the other end, and a resistor 20 for bridge configuration connected at one end to the other end of the coil 14 constituting the second displacement detector 4.
A variable resistor 21 for balance adjustment having a first terminal connected to the other end of the resistor 19, a second terminal connected to the other end of the resistor 20, and a sliding terminal connected to the other end of the resistor 17. And the first and second displacement detectors 3, 4
And the resistors 17, 19, 20 and the variable resistor 21 form a bridge, and the first and second displacement detectors 3 and 4 are excited by the exciting AC voltage output from the exciting AC power supply circuit 2. When this is done, an AC voltage corresponding to the impedances of the first and second displacement detectors 3 and 4 is generated, and this is used to form the transformer 12 that constitutes the transformer circuit 7.
Is supplied to each terminal of the primary coil 12a.

Further, the synchronous rectification circuit 6 has a ground terminal grounded, a first synchronous rectification AC power supply 22 for generating an AC voltage having a preset frequency, voltage value, and phase, and one end for the first synchronous rectification. A resistor 23 connected to the power supply output terminal of the AC power supply 22, a second AC power supply 24 for synchronous rectification, whose ground terminal is grounded, and which generates an AC voltage having a preset frequency, voltage value, and phase, and one end of which is the above-mentioned. A resistor 25 connected to the power supply output terminal of the second AC power supply for synchronous rectification 24;
One diode 26-29 and four resistors 30-33
And a bridge circuit 34 that generates an exciting voltage for synchronous rectification based on the AC voltage supplied through the resistors 23 and 25.

Then, the first and second AC power supplies 2 for synchronous rectification
2 and 24 generate an AC voltage for synchronous rectification corresponding to the phase, frequency and voltage value of the AC voltage output from the exciting AC power supply circuit 2, and the bridge circuit 34 excites the AC voltage based on the AC voltage. A voltage is generated, and the voltage is generated, and the resistors 35 and 36 that configure the transformer circuit 7 are generated.
Supply at one end of.

In the transformer circuit 7, each end of the primary coil 12a is connected to the first and second terminals of the variable resistor 21 constituting the AC bridge circuit 5, and the center point is the ground terminal of the exciting AC power supply circuit 2. To the transformer 12, one end of which is connected to the first output terminal of the bridge circuit 34, the other end of which is connected to one end of the secondary coil 12b of the transformer 12, and one end of which is the bridge. A resistor 36 connected to the second output terminal of the circuit 34 and the other end of which is connected to the other end of the secondary coil 12b of the transformer 12.
And a capacitor 37 having one end connected to one end of the resistor 35 and the other end connected to one end of the resistor 36.

The primary coil 12a of the transformer 12
Receives the AC voltage output from the AC bridge circuit 5 and receives the excitation voltage for synchronous rectification output from the synchronous rectification circuit 6 by the resistors 35 and 36 to excite the secondary coil 12b of the transformer 12. As a result, a difference voltage of the AC voltage output from the AC bridge circuit 5 is generated, which is taken out from the midpoint of the secondary coil 12b and supplied to the signal processing circuit 9.

The rotation speed detection circuit 8 is arranged so as to face the rotation speed detection gear 39 provided on the axle of the turbine rotor and the tooth surface of the rotation speed detection gear 39, and Each time a tooth passes, a rotation speed detector 40 that detects this and generates a pulse signal, and a pulse signal output from this rotation speed detector 40 are taken in to measure the rotation speed of the turbine rotor axle. , And a rotation speed measurement circuit 41 for generating rotation speed detection data based on the measurement result, and when the rotation speed detection gear 39 provided on the axle of the turbine rotor rotates, This is detected to generate a pulse signal, and the rotation speed measurement circuit 41 measures the pulse signal to generate a rotation speed detection signal. It generates a peripheral velocity detection data indicating the circumferential velocity S of the flange 18 provided on the rotor axle (rotation speed detection data), and supplies this to the signal processing circuit 9.

S [m / s] = (2πr · rpm) / 60 where r: radius of the flange 18 rpm: rotational speed of the axle of the signal processing circuit 9 is grounded at the ground terminal and the signal input terminal is at the secondary coil. 12b is connected to the midpoint, and the voltage signal output from the midpoint of the secondary coil 12b is taken in to A
It has an A / D conversion circuit 42 for A / D conversion and a CPU for processing various kinds of information, and the A / D conversion circuit 4 is based on the rotation speed detection data output from the rotation speed detection circuit 41.
And a central processing circuit 43 for correcting the voltage data output from No. 2 according to the rotation speed of the axle.
A bus line 44 connected to the bus line 44, a ROM circuit 45 connected to the bus line 44 for storing a program that regulates the operation of the central processing circuit 43 and various constant data, and the bus line 44. The RAM circuit 46 used as a storage area for a rotation speed error correction table for correcting an output error due to the work area and the rotation speed of the central processing circuit 43, and the central processing circuit 43.
And a D / A conversion circuit 47 that takes in the rotation speed-corrected voltage data output from the device and D / A converts it to generate a voltage signal.

Then, the A / D conversion circuit 42 takes in the voltage signal output from the midpoint of the secondary coil 12b constituting the transformer 12, and A / D converts this voltage signal to generate voltage data. Based on the rotation speed detection data output from the rotation speed detection circuit 8 by the processing circuit 43, the rotation speed error correction table stored in the RAM circuit 46 is referred to and output from the A / D conversion circuit 42. After correcting the rotation speed of the voltage data
The / A conversion circuit 47 D / A-converts the rotation speed-corrected voltage data to generate a voltage signal, which is supplied to the V / I conversion circuit 10.

The V / I conversion circuit 10 is a circuit whose signal input terminal is connected to the output terminal of the D / A conversion circuit 47 which constitutes the signal processing circuit 9, and the rotation speed output from the signal processing circuit 9. While taking in the corrected voltage signal, this voltage signal is V / I converted into a current signal,
This is supplied to the output generation circuit 11.

The output generating circuit 11 has a resistor 50 having one end grounded, a resistor 53 having one end connected to the output terminal 51 and the other end of the resistor 50, and an anode having the other end of the resistor 53. And a constant voltage diode 55 connected to the output terminal 52 and having a cathode connected to the output terminal and the output terminal 54 of the V / I conversion circuit 10, and the current output from the V / I conversion circuit 10. A signal is taken in, a plurality of signals are generated based on the current signal, and the signals are output from the output terminals 51, 52, 54.

As described above, in this embodiment, while the rotational speed of the turbine rotor is detected by the rotational speed detection circuit 8, the excitation AC power supply circuit 2 causes the first and second displacement detectors 3 and 4 and the AC The bridge circuit 5 is driven to generate an AC signal according to the expansion difference between the ground portion of the turbine casing and the turbine rotor, and the synchronous rectification circuit 6
After the transformer circuit 7 is driven to synchronously rectify the AC signal generated by the AC bridge circuit 5, the signal processing circuit 9 obtains the synchronous rectification operation based on the detection result of the rotation speed detection circuit 8. The voltage signal is corrected for the number of revolutions, and this is converted to V by the V / I conversion circuit 10.
After the I / I conversion into the current signal, the output generation circuit 11
Since the current signal is converted into a plurality of signals and output by the above, the rotation speed of the turbine rotor increases,
Even if the action of the virtual secondary circuit generated in the flange 18 of the axle becomes large, the expansion difference between the gland portion of the turbine casing and the turbine rotor can be accurately detected.

FIG. 2 is a block diagram showing another embodiment of the non-contact displacement measuring circuit according to the present invention. In this figure, the same parts as those in FIG. 1 are designated by the same reference numerals.

The non-contact displacement measuring circuit 1 shown in FIG.
The difference from the circuit shown in FIG.
0 and the second high-speed sampling circuit 61 are added, and a temperature correction table is provided in the RAM circuit 46 of the signal processing circuit 9 to form the coils 13 and 14 constituting the first and second displacement detectors 3 and 4, respectively. When the DC resistance value of the first and second high speed sampling circuits 60, 6 changes.
1 to detect this, and the signal processing circuit 9 performs temperature correction of the voltage signal output from the midpoint of the secondary coil 12b forming the transformer 12 to obtain the temperature characteristics of the first and second displacement detectors 3 and 4. This is to correct the differential expansion output characteristic due to.

The first high-speed sampling circuit 60 is a current value detection circuit for sampling the voltage across the resistor 19 constituting the AC bridge circuit 5 at a high speed to obtain a current value, and the coil 13 constituting the first displacement detector 3. Of the coil 13 in the first displacement detector 3 based on the voltage value detection circuit for sampling the voltage across the terminals at high speed and the voltage value and current value obtained by these voltage value detection circuit and current value detection circuit. An arithmetic circuit for calculating the resistance value is provided, and the voltage across the resistor 19 is sampled at high speed by the current value detection circuit, and the operation shown in the following equation is performed to calculate the current value I flowing through the resistor 19. , I = V1 / R, where V1: resistor 1 obtained by high-speed sampling
9 voltage value R: resistance value of the resistor 19 The voltage value detection circuit samples the voltage across the coil 13 constituting the first displacement detector 3 at high speed, and the voltage value obtained thereby and the current value I After calculating the impedance (gap impedance) Z of the coil 13 in the first displacement detector 3 by performing the calculation shown in the following equation, Z = V2 / I where V2: the first displacement detector 3 The voltage value of the coil 13 that constitutes the DC resistance value R of the coil 13 that constitutes the first displacement detector 3 is calculated by performing the calculation shown in the following equation using a calculation circuit,
This is supplied to the signal processing circuit 9 as DC resistance value data.

R = (Z ² −2πfL ² ) ^1/2 where f is the frequency of the AC voltage output from the exciting AC power supply circuit 2 L is the inductance of the coil 13 forming the first displacement detector 3 Since the inductance L of the coil 13 forming the first displacement detector 3 has almost no temperature characteristic from the test result, and the change due to temperature can be ignored, the inductance L with respect to the gap is measured in advance. The ambient temperature of the coil 13 can be obtained based on the DC resistance value R of the coil 13 that constitutes the 1-displacement detector 3.

The second high-speed sampling circuit 61, like the above-described first high-speed sampling circuit 60, detects the current value I by sampling the voltage across the resistor 20 constituting the AC bridge circuit 5 at high speed. A circuit, a voltage value detection circuit for sampling the voltage across the coil 14 constituting the second displacement detector 4 at high speed, and a voltage value V2 and a current value obtained by these voltage value detection circuit and current value detection circuit. And a calculation circuit that calculates the DC resistance value R of the coil 14 that constitutes the second displacement detector 4 based on I. The current value detection circuit samples the voltage across the resistor 20 at high speed, The current value I flowing through 20 is calculated, and the voltage across the coil 14 of the second displacement detector 4 is sampled at high speed by the voltage value detection circuit. The voltage value V2 obtained by the impedance of the coil 14 constituting the second displacement detector 4 on the basis of said current value I (gap impedance)
After calculating Z, the coil 1 forming the second displacement detector 4
The DC resistance value R of 4 is calculated, and this is supplied to the signal processing circuit 9 as DC resistance value data.

The RAM circuit 46 is the central processing circuit 43.
Used as a work area for the first and second
A portion that stores a temperature error correction table that corrects the output error due to the ambient temperature, which is indicated by the DC resistance value R output from the high-speed sampling circuits 60 and 61, and a rotation speed error correction that corrects the output error due to the rotation speed. When the temperature error correction table is accessed by the read command output from the central processing circuit 43, the temperature correction data in the part corresponding to the access command is read and stored. To the central processing circuit 43, and when the rotational speed error correction table is accessed by the read command output from the central processing circuit 43, the rotational speed correction data in the portion corresponding to the access command is read and this is read. It is supplied to the central processing circuit 43.

The signal processing circuit 9 uses the A / D conversion circuit 42 to form the secondary coil 1 which constitutes the transformer 12.
The voltage signal output from the midpoint of 2b is taken in, A / D converted to generate voltage data, and the central processing circuit 43 outputs the rotational speed detection data output from the rotational speed detection circuit 8 and the first rotational speed detection data. , The A / D conversion circuit while referring to the rotation speed error correction table and the temperature error correction table stored in the RAM circuit 46 based on the DC resistance value data output from the second high speed sampling circuits 60 and 61. After the voltage data output from 42 is rotational speed corrected and temperature corrected, the D / A conversion circuit 47 takes in the rotational speed corrected and temperature corrected voltage data and A / D converts this to convert it into a voltage signal. , V / I conversion circuit 1
Supply to 0.

As described above, in this embodiment, the exciting AC power supply circuit 2 is used while detecting the rotation speed of the turbine rotor by the rotation speed detecting circuit 8 as in the above-described embodiments.
Drive the first and second displacement detectors 3 and 4 and the AC bridge circuit 5 to generate an AC signal according to the difference in expansion between the ground portion of the turbine casing and the turbine rotor, and the synchronous rectification circuit. 6, the transformer circuit 7 is driven to synchronously rectify the AC signal generated by the AC bridge circuit 5, and then the signal processing circuit 9 obtains the synchronous rectification operation based on the detection result of the rotation speed detection circuit 8. After correcting the voltage signal, the V / I conversion circuit 10 converts the voltage signal into a current signal,
Since the output signal is converted into a plurality of signals and output by the output generation circuit 11, the rotation speed of the turbine rotor is increased and the action of the virtual secondary circuit generated in the flange 18 of the axle is increased. Also, the difference in expansion between the gland portion of the turbine casing and the turbine rotor can be accurately detected.

Furthermore, in this embodiment, the first and second high speed sampling circuits 60 and 61 change the DC resistance value which changes according to the ambient temperature of the coil 13 constituting the first displacement detector 3 and the second displacement. Coil 1 that constitutes detector 4
A secondary coil 1 that detects a DC resistance value that changes according to the ambient temperature of 4 and forms a transformer 12 with a signal processing circuit 9.
Since the voltage signal output from the midpoint of 2b is temperature-corrected, a gap measurement error does not occur even if the ambient temperature of the first and second displacement detectors 3 and 4 changes. be able to.

[0050]

As described above, according to the present invention, in claim 1, even if the rotation speed of the turbine rotor is increased and the action of the virtual secondary circuit generated in the flange of the axle is increased, the turbine is rotated. It is possible to accurately detect the difference in expansion between the ground portion of the passenger compartment and the turbine rotor. Further, in claim 2, even if the temperatures of the first and second displacement detectors change,
The expansion difference between the gland portion of the turbine casing and the turbine rotor can be accurately detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a non-contact displacement measuring circuit according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the non-contact displacement measuring circuit according to the present invention.

FIG. 3 is a block diagram showing an example of a conventionally known non-contact displacement measuring circuit.

[Explanation of symbols]

1 Non-contact Displacement Measurement Circuit 2 Excitation AC Power Supply Circuit 3 First Displacement Detector 4 Second Displacement Detector 5 AC Bridge Circuit 6 Synchronous Rectifier Circuit 7 Transformer Circuit 8 Rotation Speed Detection Circuit 9 Signal Processing Circuit 10 V / I Conversion Circuit 11 Output Generation Circuit 13 Coil 14 Coil 18 Flange (Object to be Measured) 22 First Synchronous Rectification AC Power Supply (Synchronous Rectification AC Power Supply Circuit) 24 Second Synchronous Rectification AC Power Supply (Synchronous Rectification AC Power Supply Circuit) 60 First high-speed sampling circuit (resistance value detection circuit) 61 Second high-speed sampling circuit (resistance value detection circuit)

Claims (2)

[Claims] 1. An exciting AC power supply circuit generates an exciting AC voltage to excite two coils whose inductance changes in accordance with the amount of movement of an object to be measured, and an AC bridge circuit for each of the coils. In addition to extracting the difference signal of the electric signal according to the impedance of, the synchronous rectification AC power supply circuit synchronously rectifies the difference signal by synchronously exciting the transformer circuit, in the non-contact displacement measurement circuit for generating a DC voltage signal, A rotation speed detection circuit that detects a rotation speed of the object to be measured and generates a rotation speed signal, and a synchronization that is output from the transformer circuit based on the rotation speed of the object obtained by the rotation speed detection circuit. A non-contact displacement measuring circuit comprising: a signal processing circuit that corrects the number of revolutions of a rectified DC voltage signal. 2. An exciting AC power supply circuit generates an exciting AC voltage to excite two coils whose inductance changes in accordance with the amount of movement of an object to be measured, and an AC bridge circuit for each of the coils. In addition to extracting the difference signal of the electric signal according to the impedance of, the synchronous rectification AC power supply circuit synchronously rectifies the difference signal by synchronously exciting the transformer circuit, in the non-contact displacement measurement circuit for generating a DC voltage signal, A resistance value detection circuit that calculates the DC resistance value of each coil by measuring the value of the current flowing through each coil and the voltage across each coil, and the DC resistance value of each coil obtained by this resistance value detection circuit. The temperature of each of these coils is calculated based on the following, and the synchronously rectified DC voltage signal output from the transformer circuit based on the calculation result. Non-contact displacement measurement circuit, wherein a signal processing circuit for temperature compensation, further comprising a.