SU1520369A1 - Stroboscopic meter of pressure - Google Patents

Abstract

The invention relates to a measurement technique and allows to automate the process of measuring the rapidly varying pressure of piston heat engines and compressors. For this, a stroboscopic pressure meter, along with an external pressure line 1 with an exemplary pressure gauge 2, a receiver 3 and a pressure regulator 4, a differential pressure sensor 5, a pressure equality pulse generator 13 and a piston initial position sensor 9, a driver 11 cycle pulses, pulse counter 12, control unit 14 and interface block 15 connected to computer 16. Control unit 14 contains a digital-to-analog converter, a comparator and a power amplifier. The device allows automatic removal of the characteristic of the dependence of pressure in the engine cylinder on the position of the piston or the angle of rotation of the flywheel of the shaft of the diagnosed machine. 1 hp f-ly, 7 ill.

Description

The invention relates to a measurement technique and to be used to measure the rapidly changing pressure of reciprocating heat engines and compressors.

The aim of the invention is to automate the measurement process.

Figure 1 shows a block diagram of a stroboscopic pressure meter; Fig. 2 is a functional diagram of the control unit j in Fig. 3; a functional diagram of the photoelectric sensors of the initial and current positions of the piston i in Fig. 4 is a schematic diagram of a pulse shaper for the cycles of Fig. 5 are time diagrams explaining the operation of the pulse shaper J 6 and 7 is a block diagram of a control computer program.

The stroboscopic pressure gauge-1Peni contains (Fig. 1) an external pressure pipe 1 with an exemplary manometer 2, a receiver 3 and a pressure regulator 4, a differential pressure sensor 5 connected between the external pressure pipe and a thermal machine under investigation, for example, a cylinder 6c a piston 7, a quantizing disk 8 with holes, a photoelectric sensor 9 of the initial position of the piston, a photoelectric sensor to the current position of the piston, a driver 11 cycle pulses, a counter 12 pulses., a driver 13 pulses equal a pressure control unit 14 and interface unit 15., connected to a computer 16

The control unit 14 comprises (FIG. 2) a digital-to-analog converter 17, a comparator 18 and a power amplifier 19. An electropneumatic valve is used as the pressure regulator 4. Shaper 11 pulse cycle is made (figure 4) on two series-connected triggers with a counting input. Shaper 13 pulses of equal pressure generates short pulses, the duration of which is determined by the speed of the computer 16, on the front and rear edges of the pulse coming from the output of the differential pressure sensor 5. As the interface unit 15, a multichannel module of parallel input-output of discrete s. Signals (of type MS 8402 Electronics) can be used.

The stroboscopic pressure meter operates as follows.

Differential pressure sensor 5 (does not connect through the holes to the test chamber 6 of the piston machine (Fig. 1). When the machine is operating, the pressure in chamber 6 varies from a certain minimum to a maximum value, the values of which are known a priori and entered into computer program 16 as initial information (FIG. 6). Before starting measurements using an external pressure source (not shown in FIG. 1), line 1 sets a pressure that exceeds the maximum pressure in the test chamber 6. Measurements start by setting in the computer 16 code m the maximum pressure in the chamber under study 6 Pja PMWKC., which is supplied through the interface 15 to the first inputs of the control unit 14 is converted by a digital-to-analog converter 17 (FIG. 2) to an analog signal. This analog signal is fed to the first input of the comparator 18, to the second the input of which from the electrical output of the reference pressure gauge 2 is supplied with another analog signal, the value of which is proportional to

pressure P

ext.

in highway 1. When

five

0

five

0

five

In this case, the signal at the second input of the comparator 18 exceeds the value of the signal at its first input and at the outputs of the comparator 18, and the amplifier 19 is set. Signals of the logical zero and one are added, respectively, the first of which is supplied. at the first input of the interface 15 and indicates a lack of readiness for external pressure, Pg ,; P 30. ,, the second opens pressure regulator 4 and the overpressure is released from line 1. As soon as pressure in line 1 is compared with aadann. computer program 16 value, P 8 cesh PjQ, on the first and second outputs of control unit 14, the signals are reversed, while pressure regulator 4 closes, and in computer 16, the first input of the interface unit 15 receives an external pressure ready signal.

When rotating the quantizing disk 8, the sensors 9 and 10 generate pulses of the initial and current positions of the piston 7. The shaper 11 generates a pulse cycle, the duration of which

corresponds to the time of rotation of the disk 8 to 720, the cycle pulses are fed to the control input of the counter 12 allowing counting the pulses of the current position of the piston 7 arriving at the counting input of the counter 12 from the output of the sensor 10 contains 360 holes of the current position of the piston 7). The cycle pulses from the output of the imaging unit 11 also come through the second input of the block

15conjunctions in computer 16, where they are used to generate a ready signal at the beginning of a cycle. This is necessary because the ready signal at external pressure can enter the computer 16 in the interval between the beginning and the end of the cycle pulse. The readiness signal at the beginning of the cycle is generated in the computer 16 by software, the beginning of the cycle is taken to start the second pulse of the cycle after the formation of the readiness signal by external pressure. If, in the presence of ready signals at the external pressure and the beginning of the cycle, the computer 16 does not receive a signal from the generator 13, i.e., the pressure in the test chamber 6 does not reach the value set in line 1, the computer

16 through the interface unit 15, in the first inputs of the control unit 14, will decrease the set pressure value by one step and the described process will be repeated again until at least one Input signal is received on the computer 16 during the pulse cycle time, which will allow the computer 16 to read the code, received on the fourth inputs of the block 15 interface with the outputs of the counter 12. Further, depending

from a particular program, the computer 16 performs either a single data entry at each set pressure,

SRI P

 is ensured by consistently decreasing the pressure in .... line 1 by one step after each measurement cycle, if any. both readiness signals, or multiple input at each established RZC, .. to obtain statistical values of the measured value. The measurement process ends when the pressure in the chamber 6 for the first time does not reach the next value established in the line 1, P, „. RL, „„, when the above conditions for entering into the computer 16 are fulfilled.

c. Since during the operation of piston mains, the pressure in some of the chambers under study 6 varies in both directions with respect to atmospheric pressure (for example, in cylinder 6 in cycles

0 suction and compression), then to obtain all settable values of external pressure, the input of pressure regulator 4 must be connected to a vacuum pump.

5 Thus, the electrical circuit of the device allows automation of the process of pressure measurements. This also increases the safety of the maintenance of the diagnosed

0 Setting and can be expanded range of measurements.

Claims (2)

Invention Formula 5 1 A stroboscopic pressure gauge containing an external pressure line with an exemplary manometer, a receiver and a pressure regulator, a piston initial position sensor, a pressure equalizer pulse generator, and a differential pressure sensor S connected to an external pressure line and the differential pressure sensor connected to the input of the pulse pressure equalizer pulse generator, so that, in order to automate the process g of measurements, it is equipped with a sensor of the current position of the piston, a pulse shaper of the cycle, a pulse counter, a control unit and an interface unit connected to a computer; the first outputs and the first input of the interface unit are connected respectively to the first inputs and the first output of the control unit The second input and the second output of which are connected respectively with the output of the reference pressure gauge and the control inputs of the pressure regulator, the output of the piston initial position sensor is connected through a pulse shaper of the pulses with the control. the input of the pulse counter and the second input of the interface block; the output of the equalizer pressure pulse generator is connected to the third input of the interface block. 0 five five 0 five the output of the sensor of the current position of the piston is connected to the counting code of the pulse counter, the outputs of which are connected to the fourth inputs of the interface block. 2. A pressure gauge according to claim 1, characterized in that in it the control unit contains successively connected digital channels A digital converter, a comparator and an amplifier, the inputs of the digital input, the first converter and the second input of the comparator are respectively connected to the first and second inputs of the control unit, and the outputs of the comparator and amplifier are connected respectively to the first and second outputs of the control unit. t, Fi2.g Wir s Jt L g- "IJ Fy -0 Outlet 52G YOU) (. I -0-1-5a Jt -iS VUH ig, 6