SU1516757A1 - Strain-measuring device provided with automatic zero setting - Google Patents

Abstract

The invention relates to instrumentation, namely, strain gauge instruments, and can be used in instruments for measuring pressure in the cylinders of internal combustion engines. The purpose of the invention is to improve the measurement accuracy by automatically correcting changes in the zero level without disconnecting the pressure source. The control unit circuit is made defining the middle between the pressure pulses. By selecting the transfer coefficient of the sample-storage unit 8, the response time can be selected; at a transfer ratio of 1/2, the comparator 9 operates in the middle of the interval between the pressure pulses. The imaging unit 10 at this moment gives out a short pulse to the sampling-storage unit 5 and it stores the signal value corresponding to zero pressure. If there is a zero level shift of the tension bridge 1 and the measuring amplifier 2, then it is remembered. This signal is fed to the second input of the adder 3, where it is subtracted from the total signal. 1 il.

Description

The invention relates to a measurement technique, namely, strain gauge devices with automatic zero setting, and can be used in the development of instruments for measuring pressure in cylinders of internal combustion engines.

The aim of the invention is to improve the measurement accuracy by automatically correcting large changes in the zero level, arising due to the effect of high temperatures without disconnecting the pressure source.

The drawing shows a block diagram of a strain gauge device.

The device consists of a strain gauge 1, to the measuring diagonal of which the measuring amplifier 2 and the correction channel adder 3 are connected in series, consisting of the compensating amplifier 4 and the first sampling-storage unit 5 connected in series. The control block, the output of which is connected to the control input of the correction channel storage block 5, is made up of a series-connected input driver 6, integrator 7, second sample-storage block 8, comparator 9 and output driver 10, two series-connected intermediate drivers 11 and 12 and key 13. The output of the input shaper 6 is connected to the inputs of both intermediate shapers 11, 12 connected in series with each other. 12. The output of the first one of them 11 is connected to the sample-storage unit 8, the output of watts cerned integrator through a control key 7 13 - 7 with an integrator, the output of which is coupled to the second input of the comparator 9.

Strain gauge device works as follows.

When pressure pulses arrive, they are converted by the strain bridge 1 and the measuring amplifier 2 into the corresponding electrical pulse signal, which is fed to the adder 3, the amplifier 4 and the former 6. The former 6 converts it into square impulses and outputs the integrator 7 and the former 11 and 12. The former 12 through the key 13 zeroes the integrator 7 for the duration of the pressure pulse. Between the pressure pulses, a linearly rising voltage appears at the output of integrator 7.

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The shaper 11 generates a short pulse corresponding to the leading edge of the pressure pulse to control the sampling-storage unit 8, which stores the voltage currently on the integrator 7o. The voltage from the integrator 7 and the sampling-storage unit 8 goes to the comparator 9, which, when these signals coincide, changes its state. By selecting the transfer coefficient of the sample-storage unit 8, the response time can be selected; at a transfer ratio of 1/2, the comparator is triggered in the middle of the interval between pressure pulses. The imaging unit 10 at this point injects a short pulse to the sampling-storage unit 5, and it stores the signal value corresponding to zero pressure. If there is a zero level shift of the strain bridge 1 and the measuring amplifier 2 due to temperature or other factors, then this shift is remembered. This signal is fed to the second input of the adder 3, where it is subtracted from the total signal.

It is possible to enable the correction channel between the output of the adder 3 and its second input about

Thus, the described construction of correction and control circuits makes it possible to correct the zero shift of the measuring transducer when measuring pulse pressures, without disconnecting the pressure source, i.e. always bind the momentum to zero.

Claims (1)

Invention Formula An automatic zero-setting strain gauge device containing a strain gauge bridge connected in series, a measuring amplifier and an adder, a correction channel consisting of a compensating amplifier connected in series and a first sampling-storage unit connected to the second input of the adder, and a control unit whose output is connected to the control the input of the sampling-storage channel of the correction channel, which is so that, in order to increase the measurement accuracy by automatically correcting the change of the zero level without disconnecting the pressure source, control unit vy515167576 It is removed from the series of connectors, the output of the first of which the input shaper, the integral is connected to the second sampling unit, the second, the second sampling unit, and the output of the second is connected to a comparator and an output key, connected to the integrator, l, two consecutively connected which exit is connected with the second entrance intermediate formers and a kpyu-comparator, the second output of the measuring device, the output of the input forming amplifier is connected to the input block connected to the inputs of both control sequence and the input compensating interconnected intermediate forms.