SU121252A1 - Vibrometer - Google Patents

Description

Vibrometers for measuring vibrations of oscillating or rotating objects are known, including a capacitive sensor that changes capacitance due to the vibration of a test object, fixed permanently or on a portable handle and made in the form of a capacitor. The moving capacitor plates are brought into oscillatory motion from contact with the test object and are included in an electronic circuit with a detector, an amplifier and an instrument measuring the amount of vibration.

Measuring instruments with a capacitive sensor are also known. They contain two high-frequency generators connected by a beating circuit, the oscillating circuit of one of which includes a capacitive sensor causing a change in the frequency of the beating of these generators isolated on the mixer.

In these vibrometers, the contact of the sensor with the test object does not provide sufficient accuracy in measuring the magnitude of the vibration.

In the described vibrometer, the noted deficiency is eliminated by the fact that, in order to increase the accuracy of measuring the beat, for example, a spinning or twisting spindle by eliminating its contact with a capacitive sensor, the latter is made in the form of two insulated metal plates partially covering the tested spindle from opposite sides and forming with it two capacitors that change their capacitance when the spindle beats differentially, each of which is separately included in the oscillatory circuits of high-frequency generators.

№ 121252

FIG. 1 shows the proposed vibrator; in fig. 2 is a section AA in FIG. 1 on the sensor and spindle; pas figs. 3 - electric circuit of the vibrator.

The vibrator consists of a capacitive sensor and an electronic circuit with two high-frequency generators, an amplifier, a detector, another amplifier, a measuring instrument and a power supply unit.

A capacitive sensor for measuring a beat, for example, a spinning or torsional spindle / (FIGS. 1, 2 and 3), rotated by a driving belt 2 (FIGS. 1 and 2), consists of two metal insulated plates 3 to 4, partially covering the test spindle from opposite sides. These plates form, with a metal in, a counter, two capacitors Za and 4a, which change their capacitance when the spindle beats differentially. One of these capacitors, for example, Pro, is included in the oscillating circuit of a high-frequency generator assembled on triode 5 (Fig. 3), and capacitor 4a is connected to the oscillating circuit of another high-frequency generator assembled on a mixer 6. The output of the second high-frequency generator is where the beats of the frequencies of both generators are allocated, which are in accordance with the differential capacitance change of both capacitors a and 4a, due to the beating of the spindle /, connected to the input of the amplifier assembled on the pentode 7.

The amplifier is connected to a discriminator assembled on a double diode 8, which detects the beating of the frequencies of both oscillators.

A discriminator input is connected to an input of a DC amplifier assembled on a double triode 9, to the output of which is connected a measuring device W, such as an oscilloscope, or a recording device indicating or recording the beat value of the spindle being tested.

The vibrator power supply unit consists of a transformer 11, a kenotron 12, a switching block 13, depending on the supply voltage of the alternating current network, droplets 4 and capacitors / 5, which smooth the pulsation of the rectified current feeding the anodes of the lamps.

For convenience of measurement, the vibrometer sensor is mounted on a movable sliding shtativa 16 (Fig. 1), in which the electrical circuit of the vibrometer is assembled in the box 17.

The measurement of a beat, for example, a spinning or twisting spindle /, is carried out with a vibrometer in the following manner.

The plates 3 and 4 of the capacitive sensor are installed at the same distance from the spindle under test, after which the electric circuit of the vibrometer is adjusted to the zero position of the measuring device 10.

When the rotating spindle beats, the capacitance of the 3A and 4A capacitors differentially changes, as a result of which the frequency of both generators changes. The frequency beats of both generators selected on mixer 6 are amplified by a pentode amplifier 7, detected by a discriminator on a double diode 5, amplified by a direct current amplifier on a double triode 9, and the measuring device 10 connected to it indicates the value of the beating of the spindle tested.

By eliminating direct contact with the test of the Mi iM spindle of the capacitive sensor and its implementation in the form of two capacitors, which differentially change their capacity in accordance with the beat of the spindle being tested, the accuracy of measurement of this beat increases.

Subject invention

A vibrometer to measure vibration of, for example, rotating objects, including a capacitive sensor that changes capacitance due to the vibration of the object being tested, and a measuring electronic circuit using two high-frequency generators connected to the beating circuit and an instrument measuring vibration by changing the frequency of the beating generators, characterized in that, in order to improve the accuracy of measurement of the beating, for example, a spinning or torsional spindle by eliminating its contact with a capacitive sensor, the latter n isolated in the form of two metal plates partially encompassing the test spindle to opposing sides and defining with it two capacitors vary its constituents with the beating capacity the differential spindle, each of which separately included in the oscillatory circuits of high frequency generators.

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