SU892246A1 - Differentiating pressure converter - Google Patents

Description

, (5) DIFFERENTIATING PRESSURE TRANSFORMER

The invention relates to instrumentation, namely, to differential pressure transmitters or to pressure derivative conversions. Pressure transducers are known. The pressure transducer 1 is the closest to the invention. The pressure derivative transducer contains a block of pressure-sensitive elements connected via a switching circuit with an electronic differentiating device 2 ,. However, the known pressure derivative transducer has low accuracy and low reliability. The aim of the invention is to improve measurement accuracy and reliability. The goal is achieved by the fact that in a differentiating pressure transducer containing a pressure sensor associated with a differentiating circuit, the differentiating circuit contains an auto-generator with a force-sensitive resonator, an auto-generator with an unloaded resonator, a mixer with inputs of which are connected to the auto-generators, a reversible counter with a logic on-input switching circuit. and a output register, a prohibition element, a direct input connected between the mixer output and an input of a switching logic circuit, a series circuit consisting of a frequency divider, a frequency divider by two and a delay element, the input of which is connected to the output of the autogenerator with an unloaded resonator, and the output - with the reset input of the counter, the output of the frequency divider is connected to the control input of the switching logic circuit, and the output of the frequency divider by two - with the register write enable input and with the inverting input element of the ban. FIG. 1 shows a diagram of the proposed differential pressure transducer; in fig. 2 shows time diagrams of voltages at various points of the circuit, denoted by letter indices, illustrating its operation. The differential pressure transducer contains an elastic element 1, an auto-generator 2 with a highly sensitive resonator 3, an auto-generator k with an unloaded resonator 5, a mixer 6, to the inputs of which are connected the outputs of auto-generators 2 and k, a reversible counter 7 with a switching circuit 8 at the input and a register 9 at the output, element 10 prohibition, the output of which is connected to the input of the switching logic 8, and the output of the mixer 6 is connected to the direct input, a series circuit consisting of a frequency divider 11, and 12 frequency bodies 12 and delay element 13. The input of this circuit is connected to the output of the autogenerator, and the output to the reset input of the reversible counter 7- The output of the frequency divider 11 is connected to the control input of the switching logic 8, and the output of the frequency divider 12 to two is connected to the register recording enable input 9 and the inverting element 10 ban. The differential pressure transducer operates as follows. The input pressure is transformed by an elastic element 1 into a force acting on a force-sensitive resonator 3. Therefore, the oscillation frequency f of the auto generator 2 is proportional to the input pressure (Fig. 2, curve a). An auto-oscillator 4 with a resonator 5 generates oscillations of a constant frequency fg (fig. Curve with f), which are converted by a divider 11 into clock pulses with a period (fig.2, curve i). The difference frequency d at the output of the mixer 6 is also proportional to the input pressure (figure 2, curve B). The number of pulses coming from the mixer is determined by the expression N (t) uf (t) dt. about . With a linearly varying frequency Af (t), the N (t) curve has the form of a parabola (Fig. 2, curve b). Clock pulses with a period T control the switching logic 8, through 64 which pulses with a frequency d f arrive during the first clock to the subtracting input of the reversing counter 7 (figure 2, curve e), and during the second to the summing input ( figure 2, curve a). A pulse with a period of 2T from the output of the divider 12 enters the register resolution 9 at the end of the second clock, and the difference in the number of pulses arriving at the reversing counter 7 in the first and second clock is recorded in the register (Fig. 2, curves and 3) -to u (t) 61l- u (t) at This pulse arrives at the inverting input of the prohibition element 10 and stops the flow of pulses to the reversible counter 7 for the time it reads its readings. After reading the delayed pulse from the output of the delay Element 13 is fed to the reset input of the reversible counter 7, then it is filled again. In the particular case of a linearly varying pressure P f-f-la; where K is the transmission coefficient of a circuit consisting of an elastic element 1, generators 2 and C, and a mixer 6. Then the current frequency value is. “I) M. Expression (1) in view of (3) and (2) has the form -S. Thus, the difference in the number of pulses dM, written in register 9 with a period of 2 T, is proportional to the derivative of the input pressure, i.e. The proposed converter performs input pressure differentiation. The accuracy of the differentiation is determined by the speed and capacity of the reversible counter and the stability of the clock pulse generator. For example, when d and the capacity of the reversal counter is on the order of. the error does not exceed 1%. The instability of the frequency of clock pulses when using quartz resonators can be no more than 10. Thus, the total error of differentiation is much less than when using known differentiating devices, especially when measuring small values of the rate of change of pressure. Invention Formula Differentiating pressure transducer comprising a pressure sensor associated with a differentiation circuit, characterized in that, in order to increase accuracy. measurement and reliability, in it the differentiating circuit contains an auto-generator with a force-sensitive resonance | 6. 4 with a torus, an auto-generator with a non-loaded resonator, a mixer, the inputs of which are connected to the outputs of the auto-generators, a reversible counter with switching logic at the input and a register at the output, a prohibition element, a forward input connected between the mixer output and the input of the switching logic circuit, a series circuit, consisting of a frequency divider, a frequency divider by two, and a delay element, the input of which is connected to the output of the oscillator with an unloaded resonator, and the output to the reset input of a reversible counter, eating frequency divider output coupled to a control input of the switching logic circuit, and an output divider for chasto.ty dvado register write enable input and the inverting input of the prohibition. Sources of information taken into account in the examination 1. USSR author's certificate number, cl. G 01 L 9/08, 197+. 2. USSR Author's Certificate No. ij92770, cl. G 01 L 23/18, 1973 (prototype).

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Claims (1)

Claim A differentiating pressure transducer containing a pressure sensor associated with a differentiating circuit, characterized in that, in order to improve the measurement accuracy and reliability, the differentiating circuit contains an autogenerator with a highly sensitive resonance 224b. , torus, oscillator with an unloaded resonator, mixer, the inputs of which are connected to the outputs of oscillators, a reversible counter with a logic switching circuit at the input and an output register, a ban element, a direct input connected between the mixer output and the input of the switching logic, after ^{, 0} the chain of de. frequency divider, frequency divider into two and a delay element, the input of which is connected to the output of the oscillator with an unloaded resonator, and ^{, 5, the} output is connected to the reset input of the reversible counter, the output of the frequency divider connected to the control input of the switching logic and the output of the frequency divider two20 do input enable register entries and with an inverting input of the ban element.