RU2284465C1 - Device for noncontact measurement of displacements - Google Patents

Abstract

FIELD: measurement technology.

SUBSTANCE: invention can be used for creating mechanical displacement transducers. Proposed device contains inductive differential transducer with two inductor coils, four diodes and capacitor. First leads of inductor coils are united. Second lead of first inductor coil is connected with anode of first diode and cathode of third diode. Second lead of second inductor coil is connected with anode of second diode and cathode of fourth diode. Cathode of first diode and anode of fourth diode are connected with first output of capacitor, being output of device. Cathode of second diode, anode of third diode and second output of capacitor are connected with common wire.

EFFECT: simplified design, increased reliability.

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Description

The invention relates to measuring equipment and can find application in instrumentation for the construction of sensors of mechanical displacements.

A device for measuring displacement [1], containing a supply transformer, a phase shifter, a bridge measuring circuit, a differential inductive sensor, an amplifier, a phase-sensitive demodulator, balancing capacitors is known.

The disadvantage of this device is its complexity and low accuracy due to the instability of the parameters of the balancing capacitors.

A device for non-contact displacement measurement [2] is also known, which contains in its measuring part an inductive differential sensor, four resistors, two diodes, a square-wave pulse generator, an inverter, a frequency divider, a transistor switch, a converter connected in a certain way. The disadvantage of this device is its complexity and low reliability.

The aim of the invention is to simplify the device and increase its reliability.

This goal is achieved by the fact that in the device for non-contact measurement of displacement, containing an inductive differential sensor with the first and second coils of inductance, the first and second diodes, the first conclusions of the first and second coils of inductance combined, the second output of the first inductor connected to the anode of the first diode, the second output of the second inductor is connected to the anode of the second diode, according to the invention, two diodes and a capacitor are additionally introduced, the second output of the first inductor in particular, connected to the cathode of the third diode, the second terminal of the second inductor connected to the cathode of the fourth diode, the cathode of the first diode and the anode of the fourth diode are connected to the first terminal of the capacitor, which is the output of the device, the cathode of the second diode, the anode of the first diode and the second terminal of the capacitor are connected to a common wire .

A comparative analysis of the proposed device with the prototype shows that the prototype contains 10 elements in the measuring part, while the proposed device contains 5 elements. From the theory of reliability it is known that the more elements in the device, the less reliable it is, therefore, the proposed device is simpler and has higher reliability.

The drawing shows a diagram of the claimed device.

The device contains the first 1 and second 2 inductors of the differential sensor, the first 3, second 4, third 5, fourth 6 diodes, capacitor 7, output 8 of the device.

The first terminals of the first and second inductors 1, 2 are combined, the second terminal of the first inductor 1 is connected to the anode of the first diode 3 and the cathode of the third diode 5, the second terminal of the second inductor 2 is connected to the anode of the second diode 4 and the cathode of the fourth diode 6. The cathode of the first and the anode of the fourth diodes 3 and 6 are connected to the first terminal of the capacitor 7, which is the output of the device 8, the cathode of the second diode 4, the anode of the third diode 5 and the second terminal of the capacitor 7 are connected to a common wire.

The device operates as follows.

In the absence of mechanical influences on the sensitive element, the ferromagnetic core associated with it is located at the same distance from inductors 1 and 2, the connection point of which is connected to an external sinusoidal voltage generator (not shown). In this case, the inductance of both coils is the same. A rectifier of positive polarity is made on diodes 3 and 5, which rectifies the current of coil 1, and on diodes 4 and 6, a rectifier is of negative polarity, which rectifies the current of coil 2. The load of both rectifiers is capacitor 7. If the inductances of both coils 1 and 2 are equal, it flows through them the same current and when rectifying it with both rectifiers on the capacitor 7, the voltage will be zero.

If there is a mechanical effect on the sensing element, the core will approach one coil, for example, coil 2, and move away from coil 1. When approaching the inductance of a ferromagnetic material, its inductance increases, and decreases when removed. The magnitude of the current through the inductor is determined by the expression

I = U / Z

where U is the voltage applied to the coil;

Z - equivalent coil resistance

Z = 2πfL

where f is the frequency of the voltage applied to the inductor;

L is the inductance of the coil,

those. the current through the inductor is inversely proportional to its inductance.

Thus, the current through the coil 1 and its rectified value will increase, the capacitor 7 will be charged to a larger value and the voltage across it will increase.

Since a rectifier of positive polarity is connected to the coil 1, the voltage across the capacitor 7 will have a positive value.

The device works similarly when the direction of mechanical action changes, but in this case the current will increase in coil 2, the capacitor 7 will be charged more through a rectifier of negative polarity and a negative polarity voltage will occur on it.

Using the proposed device allowed to create a small accelerometer.

Information sources

1. RF patent N2036413, G 01 B 7/00, 1995

2. RF patent N2191346, G 01 B 7/00, 2002 (Prototype)

Claims (1)

A non-contact displacement measuring device comprising an inductive differential sensor with first and second inductors, first and second diodes, the first terminals of the first and second inductors combined, the second terminal of the first inductor connected to the anode of the first diode, the second terminal of the second inductor connected to the anode of the second diode, characterized in that it additionally introduced two diodes and a capacitor, the second output of the first inductor connected to the third cathode about the diode, the second terminal of the second inductor is connected to the cathode of the fourth diode, the cathode of the first diode and the anode of the fourth diode are connected to the first terminal of the capacitor, which is the output of the device, the cathode of the second diode, the anode of the third diode and the second terminal of the capacitor are connected to a common wire.