SU1508091A1 - Contactless transducer of linear displacements - Google Patents

Abstract

The invention relates to the technique of electrical measurements of non-electrical quantities and can be used to accurately convert linear mechanical movements into a proportional electrical signal. In order to increase accuracy and reliability by using a resistive-inductive bridge as a displacement sensor and the design of an inductor as part of this sensor into a converter comprising a generator 1, inductance coils 10 and 14, a registration unit 19, a differential amplifier 20, a phase detector 21, bus 22 zero potential, entered the divider 2 frequency, the element is NOT 3, the element is NOT 4, the element is NOT 5, the element is NOT 6, the element is NOT 7, filter 8 low frequency, resistive-inductive bridge 9, winding 11, frame 12, rod 13, winding 15, rod 16, resistors 17 and 18. The operation of the converter is based on the linear dependence of the inductance of the coil 10 on the position of the non-magnetic rod 13, which is equivalent to a short-circuited inductively connected winding with the winding 11. 2 Il.

Description

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The invention relates to the technique of electrical measurements of non-electrical quantities and can be used to accurately convert linear mechanical movements into a proportional electrical signal.

The purpose of the invention is to improve accuracy and reliability by using a resistive-inductive bridge as a displacement sensor and a solenoid design as part of this sensor.

FIG. 1 is a block diagram of a converter; in fig. 2 - time diagram of his work.

The converter contains generator I, divider 2 frequencies, element NOT 3, element AND-NOT 4, element NOT 5, element AND-NOT 6, element AND-HE 7, low-frequency filter 8, resistive-inductive bridge 9 containing inductance coil 10 , winding 11, frame 12, rod 13, inductance coil 14, winding 15, rod 16, resistors 17 and 18, as well as registration unit 19, differential amplifier 20, phase detector 21, zero potential bus 22.

Generator 1 is connected to the input of divider 2 frequencies by 2, the outputs of generator 1 and divider 2 frequencies are connected to the inputs of two identical chains made up of consecutively connected logical elements NOT 3, 4, and NAND 5, 6. These elements together with the AND element -NON-7, the inputs of which are connected to the outputs of the elements AND-HE 4, 6, form a phase-shifting circuit of 90 ° to form the control voltage of the phase detector 21.

The output of the frequency divider 2 is connected to the input of the low-pass filter 8, designed to separate the first harmonic and form a sinusoidal voltage supply resistive-inductive bridge 9.

The first coil 10 inductance is made in the form of a single-layer dense winding 11, laid on a cylindrical non-magnetic frame 12, having a cut along the generatrix. Inside the coil 10 a cylindrical rod 13 is made, made of a non-magnetic metal and rigidly connected with a moving object under control.

The second inductance coil 14 is made in the form of a cylindrical winding 15 with an adjustable magnetic core 16. This bridge arm serves to balance and initially set the output voltage of the bridge 9, which is achieved by changing the position of the magnetic rod 16 along the winding 15.

The measuring diagonal of the bridge 9 {points aa) is connected to the inputs of the differential amplifier 20, the output of which is connected to the input of the phase detector 21,

the control input of which is connected to the output of the logical element 7 AND-NOT.

To the output of the phase detector 21 is connected to the block 19 registration.

The operation of the displacement transducer is based on the linear dependence of the inductance of the coil 10 on the position of the non-magnetic rod 13, which is an inductively coupled with the primary

,, 11 secondary winding “short-circuited winding (or secondary inductance). The magnetic coupling coefficient (mutual inductance) of the primary winding 11 and the secondary inductance of the rod 13 linearly depends on the position of the latter relative to the winding 11.

By adjusting the inductance of the coil 14, which is carried out by axial displacement of the rod 16 in the winding 15 by rotating it with a slit, initial balancing of the bridge 9 is performed at any initial position of the non-magnetic rod 13 in the coil 10. As can be seen from FIG. 2, the voltage from the generator 1 1 / g at the input of the frequency divider 2 The unit is filtered by filter 8, at the output of which the voltage t / has

5 sinusoidal shape and coincides in phase with the voltage (7lel ..

Voltages on the inductive arms of the bridge Ua. shifted relative to the supply voltage t / m by 90 °. The voltage of the measuring diagonal of the bridge 9, determined by the position of the rod 13 of the coil 10, and therefore the difference in inductance of the shoulders, is fed to the input of the differential amplifier 17, and from its output the increased voltage goes to the phase detector 21. The voltage (UV.1 also phase-shifted relative to the supply voltage of the bridge (Mind 90 °. For normal operation of the phase detector 21, its control voltage t / K must be in phase with its input voltage (Ufd. Necessary for this voltage phase shift ( The target at 90 ° is reached from 3-7 oschyu elements that implement the logic function of the form

45

UK (dd t / del) L (-L -)

As follows from FIG. 1, due to the implementation of this logical function, the switching voltage of the phase detector 21 UK is out of phase with the input voltage of the phase detector 21 t / Fd. The average value of the output voltage of the phase detector 21 (UVD is associated with a linear relationship with the magnitude of the displacement of the rod 13 in the coil 10, which is recorded in the registration unit 19. In this

The converter uses the dependence of the inductance of the coil 10 on the magnitude of the secondary inductance introduced by the non-magnetic but conductive cylindrical rod 13. This dependence is theoretically linear, and the range of its linearity, determined only by the ratio of length and diameter, of the coil can be arbitrarily large. In practice, it is advisable to use transducers of this type with a linear mix range from 10-20 to 500-700 mm.

Claims (1)

Invention Formula made in the form of a single-layer winding placed on a metal non-magnetic cylindrical frame with a cut along the generatrix, inside the frame there is a metal non-magnetic core located at the axis of the axis, the second inductance coil is configured to control the inductance, the generator output is connected to the first input of the first element and NOT, the input of the first element NOT and through the frequency divider - to the inputs of the second element NOT, the low-pass filter and the first input of the second element NAND, the output The first and second elements are NOT a non-contact linear displacement transducer containing a generator, a differential amplifier, two iEBPr resis I-NOT, the output of which is connected to the second input of the phase detector, the output of the low-pass filter through the first and second resistors is connected to the second terminals of the first and second coils, respectively The detector is connected to the first input of the phase detector, the KOjoporo output is connected to the input of the registration unit, the first terminals of the inductors are connected to the zero potential bus, characterized in that, to increase the accuracy and reliability, a frequency divider, two elements NOT, three elements AND are added to it. -NOT and low-pass filter, first solenoid inductance and, respectively, to the inverse and direct inputs of the differential amplifier. made in the form of a single-layer winding placed on a metal non-magnetic cylindrical frame with a cut along the generatrix, inside the frame there is a metal non-magnetic core located at the axis of the axis, the second inductance coil is configured to control the inductance, the generator output is connected to the first input of the first element and NOT, the input of the first element NOT and through the frequency divider - to the inputs of the second element NOT, the low-pass filter and the first input of the second element NAND, the output The first and second element s are NOT iEBPr I-NOT, the output of which is connected to the second input of the phase detector, the output of the low-pass filter through the first and second resistors is connected to the second terminals of the first and second coils, respectively inductance and, respectively, to the inverse and direct inputs of the differential amplifier. fir.2