CN116183211A

CN116183211A - Full-automatic multifunctional test bed and test method for net-shaped air inlet valve of reciprocating compressor

Info

Publication number: CN116183211A
Application number: CN202310362467.XA
Authority: CN
Inventors: 王德喜; 崔玮琳; 洪晓; 王猛
Original assignee: Shenyang University of Technology
Current assignee: Shenyang University of Technology
Priority date: 2023-04-07
Filing date: 2023-04-07
Publication date: 2023-05-30

Abstract

The invention provides a full-automatic multifunctional test bed and a test method for a net-shaped air inlet valve of a reciprocating compressor, and relates to the technical field of reciprocating compressors. The invention relates to a multifunctional test bed which comprises a cover body 1, a top cover 2, a tested air inlet valve 3, a pressure fork 4, a pressure valve cover 5, a jackscrew 6, a vortex shedding flowmeter 18, a rotor flow transmitter 19, 2 displacement sensors A12 and B13, 2 pressure transmitters PB14 and PA15, 2 temperature transmitters TB16 and TA17, 2 regulating valves PRC-A20 and PRC-B21, 3 electromagnetic valves SA22, SB23 and SC24, an upper industrial personal computer PC and a programmable controller PLC; meanwhile, the test method specifically comprises the steps of testing the elastic force of the air inlet valve, measuring the leakage quantity and testing the dynamic performance of the valve plate; the test bed can automatically perform quantitative test on the performance of the air valve, and simultaneously can perform macroscopic simulation test on the motion rule of the air valve plate of the air valve.

Description

Full-automatic multifunctional test bed and test method for net-shaped air inlet valve of reciprocating compressor

Technical Field

The invention relates to the technical field of reciprocating compressors, in particular to a full-automatic multifunctional test bed and a test method for a net-shaped air inlet valve of a reciprocating compressor.

Background

The performance of a gas valve, often referred to as the heart of a reciprocating compressor, and in particular a gas inlet valve, has a significant impact on the operating efficiency and energy consumption of the compressor. The mesh valve is the most widely used type of air valve in the reciprocating compressor at present, and the rationality of the design, the physical properties and the manufacturing quality of each component are decisive factors for the performance of the air valve. Under the condition of meeting the design pressure, the air valve performance finally shows the following four aspects: applicable flow range, drag loss, leakage and average fault interval. The final performance is determined by the effective flow area of the air valve, the thrust coefficient, flow coefficient, resistance coefficient, elastic force of the spring, valve plate lift, valve gap Mach number and other basic parameters of the air valve. There are two methods of theoretical calculation and experimentation to obtain these parameters. Theoretical calculation is based on analogy and similarity theory, and is based on graphs and curves obtained by experiments of some predecessors, but the bases are not unique, and a plurality of versions are often different from each other, and material performance and manufacturing errors are added, so that the designed and manufactured product has larger deviation from ideal necessarily. The CFD simulation calculation method which is raised in the 60 s of the last century improves the convenience of theoretical calculation, is relatively suitable for the application of the air valve design stage, but the simulation calculation method cannot predict the influence of manufacturing materials and manufacturing errors on the air valve performance. Therefore, the performance rechecking and quality inspection of the product are more accurate and reliable than the simple theoretical calculation.

The current test for the air valve has two independent technologies and equipment, namely a sealing test and an air blowing test. The utility model patents of CN213422559U and CN215004147U, etc. use the pressurizing or depressurizing method to improve the traditional kerosene leak test method, but are limited to the test of the single performance of the air valve seal. The air blowing test device is a traditional air valve performance test device, and some air valve performance test devices can test the resistance coefficient of an air valve, such as the document 'piston compressor air valve resistance loss test and research for petrochemical industry'; some are used for testing flow coefficient, and some calculate the elastic force of valve block and spring by means of deflection when valve block is stressed and loaded uniformly, so as to calculate thrust coefficient, as described in the first book of structural design of reciprocating compressor.

The existing two air valve test methods and test devices are single in function, complex in test operation, and some of the air valve test methods and test devices also need to be calculated by means of theory, so that reliability of test conclusion is reduced. At present, only few compressor and air valve manufacturing enterprises in China are provided with the two test devices. It is necessary to build a high-precision, high-automation, multi-functional test stand for the overall performance of air valves to meet and enhance the demands of product inspection, performance review, design improvement, and air valve research.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a full-automatic multifunctional test bed and a test method for a net-shaped air inlet valve of a reciprocating compressor. The test bed can automatically perform quantitative test on the performance of the air valve, and simultaneously can perform macroscopic simulation test on the motion law of the valve plate of the air valve, and automatically generate corresponding curves or tables on the test result of the performance of the air valve and the simulation result of the motion law of the valve plate.

On the one hand, the full-automatic multifunctional test bed for the net-shaped air inlet valve of the reciprocating compressor comprises a cover body 1, a top cover 2, an air inlet valve 3 to be tested, a pressure fork 4, a pressure valve cover 5, a jackscrew 6, a vortex shedding flowmeter 18, a rotor flow transmitter 19, 2 displacement sensors A12 and B13, 2 pressure transmitters PB14 and PA15, 2 temperature transmitters TB16 and TA17, 2 regulating valves PRC-A20 and PRC-B21, 3 electromagnetic valves SA22, SB23 and SC24, an upper industrial personal computer PC and a programmable controller PLC;

the top of the cover body 1 is fixed with the top cover 2 through a plurality of fastening bolts, a jackscrew 6 is arranged at the center of the top cover 2, a tested air inlet valve 3 is arranged in the cover body 1, the tested air inlet valve 3 and the cover body 1 are tightly pressed and sealed through a compensation ring 7, the top of the tested air inlet valve 3 is tightly pressed by a valve pressing cover 5, the jackscrew 6 tightly presses a valve seat of the tested air inlet valve 3 on a sealing gasket on the compensation ring 7 through the valve pressing cover 5, the compensation ring 7 is tightly pressed on the sealing gasket placed at a protruding stage of the cover body 1, a pressing fork 4 is arranged in the cover body 1, the pressing fork 4 passes through a runner of the air inlet valve 3 to be contacted with a valve plate, a pressing fork counterweight groove 25 is formed in the pressing fork 4, 2 displacement sensors A12 and B13 are arranged in the cover body 1 and are symmetrically arranged by taking the air valve center as an axis, 2 pressure transmitters PB14 and PA15 and 2 temperature transmitters TB16 and TA17 are arranged on the outer side surface of the cover body 1, a lower exhaust pipe 10 and a lower exhaust valve 11 are arranged at the bottom of the cover body 1, and the lower exhaust valve 11 is arranged on a lower exhaust pipe 10 in a threaded or welded mode.

The side of the cover body 1 is provided with an upper air inlet and outlet 9 and se:Sub>A lower air inlet 8, se:Sub>A buffer tank R is arranged behind the air source, an air inlet pipeline of the upper air inlet and outlet 9 is connected with the air source, se:Sub>A vortex shedding flowmeter 18, se:Sub>A regulating valve PRC-B21 and an electromagnetic valve SC24 are sequentially arranged on the air inlet pipeline of the upper air inlet and outlet 9, the regulating valve PRC-B21 is connected with se:Sub>A pressure automatic control system 1 to form se:Sub>A PRC-B pressure control system, the pressure automatic control system 1 is formed by se:Sub>A programmable controller PLC, se:Sub>A pressure transmitter PB14 and se:Sub>A regulating valve PRC-B21, signal lines of the pressure transmitter PB14, the programmable controller PLC and the regulating valve PRC-B21 are sequentially connected, an electromagnetic valve SB23 and se:Sub>A rotor flow transmitter 19 are arranged on the air outlet pipeline of the upper air inlet and outlet 9, the air inlet pipeline of the lower air inlet 8 is connected with the air source, the regulating valve PRC-A20 and the electromagnetic valve SA22 are arranged on the air inlet pipeline of the lower air inlet 8, the regulating valve PRC-A20 is connected with the pressure automatic control system 2 to form the PRC-A pressure control system, and the pressure automatic control system 2 is formed by the pressure transmitter PA15 and the regulating valve PRC-A20. The signal lines of the pressure transmitter PA15, the programmable controller PLC and the regulating valve PRC-A20 are sequentially connected;

the upper industrial personal computer PC is connected with the programmable controller PLC through a communication port, and an analog input AI of the PLC is respectively connected with signal lines of the vortex shedding flowmeter 18, the rotor flow transmitter 19, 2 displacement sensors A12 and B13, 2 pressure transmitters PB14 and PA15 and 2 temperature transmitters TB16 and TA 17; analog quantity output AO of the PLC is connected with signal lines of 2 regulating valves PRC-A20 and PRC-B21; the on-off output DO is connected with signal lines of 3 electromagnetic valves SA22, SB23 and SC 24;

The upper industrial personal computer PC comprises a display, a man-machine interface, test result processing and a test curve and test table generating function, and the printer prints the test result and the test curve; the test results and the test curves are established by using domestic configuration software. The test curves comprise an elastic force-valve plate lift curve, a thrust coefficient-h/b curve, a valve clearance flow coefficient-h/b curve, a valve plate lift-standard state volume flow curve, a relative pressure loss-valve clearance Mach number curve and a relation curve required among all test parameters. And setting parameters, displaying a human-computer interface, starting, stopping and printing on the upper computer.

The programmable controller PLC comprises two test programs, namely a leakage test boosting program and a dynamic performance boosting program; in the leakage quantity test boosting program, the quantity of the boosting sections and the voltage stabilizing sections is automatically calculated and determined by the PLC according to the set value. When the highest pressure is reached, the execution of other setting contents is stopped immediately; when the execution of other setting contents is finished, if the test pressure does not reach the highest pressure, the test pressure is boosted by the setting slope K until reaching the highest pressure Pm; the value of the highest pressure Pm of the dynamic performance boosting program is different from that of the leakage quantity boosting program, and the rest is the same. The two test programs are all in an automatic control mode, and are automatically executed according to a preset test program except for switching of the two test programs, so that manual intervention is not needed; and after the test is finished, automatically generating a test result and a test curve, and providing the functions of manual keyboard operation and human intervention in the process of program execution.

PID control of the programmable controller PLC is output through a virtual regulator; the virtual regulators are built through domestic configuration software, 2 virtual regulators are obtained, and an operable interface is built. The PLC controls the pressure automatic control systems 1 and 2. The 2 pressure control systems have double control functions of program control and operator keyboard control, namely, the test pressure set value has double functions of program boosting and operation boosting, so that the control output executes the automatic control output of the PLC or is switched into the manual keyboard operation output.

On the other hand, the performance test method of the net-shaped air inlet valve of the reciprocating compressor is realized based on the full-automatic multifunctional test bed of the net-shaped air inlet valve of the reciprocating compressor, and specifically comprises an air inlet valve elastic force test, a leakage measuring quantity, a dynamic performance of a test valve plate, a basic performance calculation method of the tested air inlet valve and a simulation calculation method of a macroscopic motion rule of the valve plate under a rated working condition; the method comprises the steps of carrying out a first treatment on the surface of the

The elastic force test of the air inlet valve is carried out, a pressing fork 4 is directly pressed onto a valve plate from a runner groove of a valve seat of the air inlet valve to be tested, the pressing fork 4 has no contact point with the valve seat of the air inlet valve to be tested, at the moment, the external force born by the valve plate has elastic force and the gravity of the pressing fork 4, the dead weight of the pressing fork 4 is known, weights are applied to a weight pressing fork counterweight groove 25 at the top of the pressing fork 4, the change of the total weight of the pressing fork causes the change of the lift height of the valve plate, the valve plate is pressed from the height of the valve seat to the height of the valve plate just reaching a lift limiter, the valve plate is divided into a plurality of test points to apply different counterweights, and the numerical value corresponding to the total weight of the pressing fork is read out from output signals of a displacement sensor A12 and a displacement sensor B13, so that the elastic force-valve plate lift curve can be generated;

The measuring the leakage comprises the steps of:

step A1: the tested air inlet valve, the valve pressing cover and the displacement sensor are respectively placed in the cover body in sequence, the top cover is covered, the fastening bolts on the top cover and the cover body are screwed, the jackscrews are screwed into the thread positions in the center of the cover body, and the valve pressing cover compresses the valve seat on the compensation ring through the screwing of the jackscrews. Providing an air source with se:Sub>A pressure which is 15% -25% higher than the maximum working pressure of the air cylinder in practical application, using se:Sub>A displacement sensor A12, se:Sub>A displacement sensor B13, se:Sub>A pressure transmitter PB 14, se:Sub>A pressure transmitter PA15, se:Sub>A temperature transmitter TB 16, se:Sub>A temperature transmitter TA17 and se:Sub>A rotor flow transmitter 19, opening an electromagnetic valve SA22 and an electromagnetic valve SB23, closing se:Sub>A lower exhaust valve 11, closing an electromagnetic valve SC24, stopping se:Sub>A PRC-B pressure control system, starting the PRC-A pressure control system and setting PID parameters of se:Sub>A PLC loop virtual regulator;

step A2: starting a leakage quantity test boosting program switch of the air inlet valve, and starting a test program; the gas enters from the lower air inlet, the gas leaked from the valve plate of the tested air inlet valve is discharged from the upper air inlet and outlet, and finally the gas is discharged after being metered by the rotor flow transmitter. The test pressure is increased from zero to the maximum pressure of the cylinder, the set value of the PRC-A pressure control system is increased according to se:Sub>A preset leakage test boosting program, or se:Sub>A program setting program is cut off, keyboard operation is carried out, and the test pressure at the bottom of the test bed is changed by manually changing the set value of the boosting or directly changing the output of the regulating valve; the PLC receives the signal output by the pressure transmitter PA15, the rotor flow transmitter 19 sends the leakage flow signal to the PLC, and the PLC depicts the corresponding leakage amount and pressure value as a leakage amount-differential pressure relation curve, so that the leakage amount test of the air inlet valve is finished.

The leakage amount-differential pressure relation curve takes the value of the pressure difference value of the test bed pressures PA15 and PB 14 as the reference.

The dynamic performance of the valve plate is the corresponding relation between the front and rear differential pressure of the valve plate, the lift of the valve plate and the flow rate, the pressure difference of the air inlet valve at the front and rear of the valve plate changes from the beginning to the end of the air suction process in the air suction section, and the maximum value of the differential pressure is related to the instantaneous resistance coefficient of the air valve and is smaller than the absolute pressure value of the air inlet;

the dynamic performance of the test valve plate comprises the following steps:

step B1: the tested air inlet valve, the valve pressing cover and the displacement sensor are respectively placed in the cover body in sequence, the top cover is covered, the fastening bolts on the top cover and the cover body are screwed, the jackscrews are screwed into the thread positions in the center of the cover body, and the valve pressing cover compresses the valve seat on the compensation ring through the screwing of the jackscrews. Providing an air source with pressure which is 15% -25% higher than the highest pressure difference between the upper and lower valve plates, using a displacement sensor A12, a displacement sensor B13, a pressure transmitter PB 14, a pressure transmitter PA15, a temperature transmitter TB 16, a temperature transmitter TA 17 and a vortex shedding flowmeter 18, closing an electromagnetic valve SA22 and an electromagnetic valve SB23, opening a lower exhaust valve 11, and opening an electromagnetic valve SC 24. The PRC-A20 pressure control system is deactivated, and the pressure control system in which the PRC-B21 is located is set and started. The air enters from the upper air inlet and outlet 9, passes through the tested air inlet valve and is exhausted by the lower air exhaust pipe 10.

Step B2: and starting a boost program switch for dynamic performance test of the air inlet valve, and starting the dynamic test program to run. The test pressure Pm is 110% of the upper and lower maximum pressure difference of the valve plate in actual working, the set value of the PRC-B pressure control system is boosted according to a dynamic performance boosting program or is set by a cutting program, the keyboard operation is carried out, and the boosting set value is manually changed or the test pressure at the upper part of the test bed is directly changed by changing the output of the regulating valve. The PLC receives signals output by the pressure transmitter PB14, the vortex shedding flowmeter 18 sends air inlet flow signals to the PLC, the displacement sensor A12 and the displacement sensor B13 send valve sheet lift signals to the PLC, and the PLC draws corresponding air inlet pressure, air inlet flow, average values of the displacement sensor A12 and the displacement sensor B13 into a valve sheet pressure difference-valve sheet lift and flow velocity relation curve.

And the dynamic performance test of the air inlet valve is finished.

And the differential pressure value of the valve plate differential pressure-valve plate lift and flow velocity relation curve is determined by the differential value of the test bed pressures PB14 and PA 15.

The method for calculating the basic performance of the tested air inlet valve comprises the steps of calculating the Mach number of the valve gap, calculating the thrust coefficient, calculating the effective flow area of the flow coefficient and the valve gap, and calculating the resistance coefficient and the pressure loss;

(1) Calculation of valve gap Mach number:

wherein: m is M _max -maximum mach number of valve gap flow; v _Fmax -maximum flow rate of valve gap flow; a- -the sonic velocity of the gas;

the maximum flow velocity v of the valve gap is respectively obtained _Fmax And gas sonic velocity a;

wherein: a is that _p -piston area; v _max -the highest displacement speed of the suction section piston; n is the number of air inlet valves on the same side of the cylinder; a, a _Vmax -maximum valve clearance area; alpha _V(max) -a valve gap flow coefficient corresponding to the maximum valve gap area;

formula (2) has alpha _V(max) 、a _Vmax 、v _max 3 parameters to be solved;

a _V ＝lh--------(3)

wherein: a, a _V -valve gap area; l- -the measured total edge length of the valve seat ring groove; h- -valve sheet lift;

wherein: alpha _v -valve gap flow coefficient; q _v Volumetric flow, i.e. the flow measured by a vortex shedding flowmeter; ρ _W -the operating density of the gas before the valve; ΔP- -the pressure difference between the gas before and after the valve, i.e., the pressure difference between the pressures measured by test stand PB14 and PA 15;

wherein: p (P) _B Air inlet pressure, i.e. the pressure measured by test stand PB 14; p (P) _N -standard atmospheric pressure, T _B -pre-valve gas temperature; t (T) _N -standard temperature; ρ _N -a standard density of the test gas;

in the dynamic performance test process of the test bed, the valve plates are positioned at different lift positions and correspond to different volume flows, valve clearance areas, gas working condition densities before the valve and pressure differences; when the valve plate is positioned at the maximum lift position, the maximum valve clearance area a of the air valve is obtained according to the formula 3 _Vmax Collecting data by a test bed, and calculating according to formulas 4 and 5 to obtain a valve clearance flow coefficient alpha corresponding to the maximum valve clearance area _V(max) ；

Wherein: v—the speed of movement of the suction section piston; r- -crank radius; omega- -compressor angular velocity; λ—the ratio of crank radius to connecting rod length; θ -crank angle;

differentiating the crank angle by equation 6, i.e

When (when)

Crank angle θ at which maximum thrust is obtained _m Will be theta _m Substituting formula 6 to obtain maximum moving speed v of the suction section piston _max ；

Wherein: k- -gas insulation index, R _g -the gas constant of the compressed gas;

wherein: r- -Universal gas constant, M _mol -relative molar mass of compressed gas

To this end (1) the maximum Mach number M of the valve gap is obtained _max Is calculated according to the calculation result of (2);

(2) Calculating a thrust coefficient:

wherein: beta-thrust coefficient; f (F) _g -gas force; a, a _e -the flow area of the outflow side of the valve seat; p (P) _B Air inlet pressure, i.e. the pressure measured by test stand PB 14; p (P) _A -in-cylinder pressure, i.e. the pressure measured by the test bench PA 15;

in the test process of the performance of the air inlet valve, when the dynamic performance boosting program runs in the stable time periods t2, t4 and t6, under the control of the pressure control loop PRC-B, the pressure of the upper part of the air inlet valve to be tested of the test bed is controlled to be a relatively stable pressure value, and the air thrust and the elastic force on the valve plate are balanced at the moment, namely F _s ＝F _g The average value of the 2

position sensors

12 and 13 at this time is read out, whereby the average value is calculated fromCorresponding elastic force F is automatically detected in the elastic force-lift curve obtained in the valve elastic force test _s Changing the thrust coefficient calculation formula (10) to formula (11); meanwhile, the PLC calculates the average value of the pressure difference between PB14 and PA15 in the last 10 seconds of the period of time, namely (11);

(3) Calculating the flow coefficient and the effective flow area of the valve gap:

A＝α _v a _v --------(12)

wherein: a- -the effective flow area of the valve; alpha _v -the valve gap flow coefficient of the gas valve, obtainable from equation 4; a, a _v -the valve clearance flow area of the valve, obtainable from equation 3;

as can be seen from 5.1, when the valve plate is located at different lift positions, the valve clearance area a of the valve corresponding to the different lift positions can be obtained according to the formula 3 _v Collecting data by a test bed, and calculating according to formulas 4 and 5 to obtain valve clearance flow coefficient alpha corresponding to the valve clearance area _v Obtaining valve clearance effective flow areas A corresponding to different lift positions according to a formula 12;

(4) Calculation of drag coefficient and pressure loss:

wherein: ζ - -resistance coefficient; g- -gravitational acceleration; ΔP- -the pressure difference between the gas before and after the valve, i.e., the pressure difference between the pressures measured by test stand PB14 and PA 15; v _F -valve clearance speed; ρ _W -pre-valve gas regime density, obtainable from equation 5;

Wherein: q _v Volumetric flow, i.e. the flow measured by a vortex shedding flowmeter; a, a _v The valve clearance flow area of the gas valve,as can be derived from equation 3;

the pressure loss is the permanent loss of the pressure of the fluid after passing through the valve plate, namely the pressure difference delta P between the front and the back of the air valve, and the pressure loss is equal to the difference between the measured pressure values of PB14 and PA 15;

when the front and rear temperatures of the air inlet valve are fixed, the valve gap doherty is calculated, the valve gap flow rate is directly calculated by an air inlet flow rate in a four-parameter relation curve established by the dynamic performance test of the air inlet valve through a calculation formula (2), and if the actual use pressure and temperature in front of the air inlet valve are different from the test pressure PB-14 and the test temperature TB-16, the compensation calculation is carried out by using a conventional pressure and temperature compensation technology; according to the thrust coefficient calculation method, a four-parameter relation curve established by an air inlet valve plate elastic force test and an air inlet valve dynamic performance test is directly used, the air thrust is replaced by elastic force corresponding to the same flow, and calculation is performed through a calculation formula (6); the flow coefficient calculating method directly uses the air inlet flow q in the four-parameter relation curve established by the air inlet valve dynamic performance test _v And the front-back pressure difference of the air inlet valve, and the flow coefficient alpha is calculated by a calculation formula (7) _v The method comprises the steps of carrying out a first treatment on the surface of the The resistance coefficient calculating method directly uses the calculation result of the flow coefficient to calculate the resistance coefficient through a calculation formula (10); the pressure loss calculation method directly uses the air inlet flow q in a four-parameter relation curve established by the dynamic performance test of the air inlet valve _v And the pressure difference between the front and the rear of the air inlet valve is calculated by the conventional temperature and pressure compensation technology and corresponds to the pressure difference between PB-14 and PB-15 in the test curve, and the pressure difference is the pressure loss at that time.

The simulation calculation method of the valve plate macroscopic motion law under the rated working condition is a method for establishing a time function of the valve plate lift height or the crank angle of the suction section of the compressor, and comprises a simulation calculation method of the valve plate macroscopic motion trail, a simulation calculation method of the valve plate maximum opening residence time and a simulation calculation method of the valve plate opening lag time under the rated working condition;

(1) The simulation calculation of the macroscopic motion law of the valve plate directly utilizes the corresponding relation curve of the valve plate lift height and the air inlet flow in the four-parameter relation curve obtained in the dynamic test of the air inlet valve to control the air inlet flow Q, so that a corresponding valve plate position can be obtained, the motion speed of the piston is calculated by using the formula (15), the crank angle is calculated by using the formula (16), the relative time of the angle is calculated by using the formula (17), namely, the corresponding valve plate lift height can be calculated by corresponding to one value of the control flow Q, and the valve plate lift height-time and the valve plate lift height-crank angle relation curve are depicted, wherein the following formula is shown:

v＝4Q/(π×D ² )-----------------------------(15)

V-piston movement speed, Q-air inlet flow and D-cylinder inner diameter;

(2) Calculation of valve plate maximum opening residence time under rated working condition

The movement speed of the piston in the air suction process is shown as (16), 2 corners correspond to the same piston speed in the air suction section, and if the instantaneous flow of the valve plate reaching the lift limiter is substituted into the formula (15), the time between the two corners is the time for the valve plate to stay on the lift limiter, namely the maximum opening stay time;

(3) Calculation of valve plate opening lag time under rated working condition

The opening lag time refers to the time difference between the actual opening time and the theoretical opening time of the air inlet valve; the theoretical valve opening moment of the air inlet valve is when the thrust of the air to the valve plate is equal to zero, and the actual valve opening moment is when the thrust of the air to the valve plate is equal to the elastic force, and the theoretical valve opening moment is when the expansion section of the compressor is ended, and certain delay exists between the theoretical valve opening moment and the actual valve opening moment;

the actual valve opening time t of the air valve is carried out _o According to the characteristic that the gas thrust is equal to the elastic force at the moment, firstly, calculating the pressure of the gas in the cylinder at the moment by the method (18)p ₀ Then, the volume V of the gas in the cylinder at the moment is calculated by (19) ₀ Then calculate the displacement x of the piston at that time from (20) ₀ Calculating the crank angle θ from (21) _o Further, the actual valve opening time t is calculated by (22) _o ；

F _so ＝F _go ＝β ₀ a _e (p _s -p _o )--------(18)

Wherein m- -expansion index, F _so -the elastic force of the valve when it is about to open; f (F) _go -gas force when the gas valve is about to open; beta ₀ Thrust coefficient when valve plate is stopped at valve seat, beta ₀ ＝1.0；a _e -the flow area of the outflow side of the valve seat; p is p _s -nominal intake pressure; p is p _o -in-cylinder pressure when the gas valve is closed and is about to open; v (V) _o -the upper volume of the piston when the gas valve is about to open; v (V) _y -cylinder clearance volume; p is p _d -rated exhaust pressure; x is x _o -the instantaneous displacement of the piston when the gas valve is about to open; d- -cylinder diameter; θ _o -crank angle at which the gas valve will open; r- -crank radius; λ—the ratio of crank radius to connecting rod length; t is t _o -the actual valve opening moment of the gas valve; t—compression period;

the theoretical valve opening time is that the gas pressure in the cylinder is equal to the air inlet pressure, and the time gas is calculated by (23)Volume V of in-cylinder gas _s Then calculating theoretical valve opening time according to the formulas (24), (25) and (26), and finally calculating the lag time delta t of the actual valve opening according to the formula (27) ₂ ；

/>

△t ₂ ＝t _o -t _s --------(27)

Wherein: v (V) _s -the piston upper volume at the end of the expansion section; v (V) _y -cylinder clearance volume; p is p _d -rated exhaust pressure; p is p _s -nominal intake pressure; x is x _s -the instantaneous displacement of the piston at the end of the expansion section; θ _s -crank angle at the end of the expansion section; t is t _s -theoretical opening moment of the air valve; t is t _o -the actual valve opening moment of the gas valve; t—compression period; Δt (delta t) ₂ -lag time for valve opening.

The beneficial effects of adopting above-mentioned technical scheme to produce lie in:

the invention provides a full-automatic multifunctional test bed for a reticular air inlet valve of a reciprocating compressor, which adopts the technical scheme and has the beneficial effects that:

(1) The invention can automatically test the mesh air inlet valve under the conditions of multistage pressure, multiple performances and preset program setting, and automatically generate a test curve or report;

(2) The invention can simulate the practical application working condition or the design working condition, macroscopically calculate the motion rule of the valve plate according to the test result to obtain the holding time of the maximum opening and the time corresponding motion trail of various openings;

(3) According to the invention, various important air valve performance parameters such as flow coefficient, effective flow area, thrust coefficient, resistance coefficient, air gap Mach number, air inlet valve pressure drop and the like of the tested net-shaped air inlet valve can be automatically calculated according to test results of various different working conditions, different lift positions of the valve plate and different air inlet flow rates and known structural dimensions of the air inlet valve;

(4) According to the invention, test basis can be provided for the structural design of the air valve and the determination of design parameters such as optimal valve plate lift, maximum air inlet flow, minimum air inlet flow and the like according to test data and calculation results;

(5) The invention can automatically calculate the valve plate opening time, the valve plate opening lag time, the valve plate closing time and the valve plate closing lag time;

(6) Compared with the existing blowing device and leakage test device, the invention not only can realize the functions, but also has high automation degree, flexible and convenient operation, can automatically generate function curves of various required measurement parameters and calculation parameters, and has great expandability in test items and calculation contents. For example, a stepless air quantity regulating system for jacking time control can be used for calculating theoretical valve closing time of different compressed air quantities by using the test bed and the test method.

Drawings

FIG. 1 is a diagram of a full-automatic multifunctional test bed for a reciprocating compressor mesh air inlet valve in an embodiment of the invention;

in the figure, se:Sub>A 1-cover body, se:Sub>A 2-top cover, se:Sub>A 3-tested air inlet valve, se:Sub>A 4-pressure fork, se:Sub>A 5-pressure valve cover, se:Sub>A 6-jackscrew, se:Sub>A 7-compensation ring, an 8-lower air inlet, se:Sub>A 9-upper air inlet and outlet, se:Sub>A 10-lower air outlet pipe, an 11-lower air outlet valve, se:Sub>A 12-displacement sensor A, se:Sub>A 13-displacement sensor B, se:Sub>A 14-pressure transmitter PB, se:Sub>A 15-pressure transmitter PA, se:Sub>A 16-temperature transmitter TB, se:Sub>A 17-temperature transmitter TA, an 18-vortex shedding flowmeter, se:Sub>A 19-rotor flow transmitter, se:Sub>A 20-regulating valve PRC-A, se:Sub>A 21-regulating valve PRC-B, se:Sub>A 22-electromagnetic valve A, se:Sub>A 23-electromagnetic valve B, se:Sub>A 24-electromagnetic valve C and se:Sub>A 25-pressure fork counterweight groove are arranged;

FIG. 2 is a block diagram of a control system according to an embodiment of the present invention;

FIG. 3 is a graph of leak test set-up pressure for an embodiment of the present invention;

FIG. 4 is a diagram showing an elastic force test in an embodiment of the present invention;

FIG. 5 is a diagram illustrating a leak test in accordance with an embodiment of the present invention;

FIG. 6 is a dynamic test chart according to an embodiment of the present invention;

FIG. 7 is a graph of total spring force versus valve plate lift height for an embodiment of the present invention;

FIG. 8 is a graph of thrust coefficient versus lift height versus seat seal face channel width for an embodiment of the present invention;

FIG. 9 is a graph of leakage versus differential pressure in an embodiment of the present invention;

FIG. 10 is a graph of differential pressure versus valve plate lift and flow rate in an embodiment of the present invention.

Detailed Description

The following describes in further detail the embodiments of the present invention with reference to the drawings and examples. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.

On the one hand, as shown in fig. 1, the full-automatic multifunctional test stand for the net-shaped air inlet valve of the reciprocating compressor comprises a cover body 1, a top cover 2, an air inlet valve to be tested 3, a pressure fork 4, a pressure valve cover 5, a jackscrew 6, a vortex shedding flowmeter 18, a rotor flow transmitter 19, 2 displacement sensors A12 and B13, 2 pressure transmitters PB14 and PA15, 2 temperature transmitters TB16 and TA17, 2 regulating valves PRC-A20 and PRC-B21, 3 electromagnetic valves SA22, SB23 and SC24, an upper industrial personal computer PC and a programmable controller PLC;

The top of the cover body 1 is fixed with the top cover 2 through a plurality of fastening bolts, a jackscrew 6 is arranged at the center of the top cover 2, and when the leakage amount test and the dynamic performance test of the air inlet valve of the compressor are carried out, the top cover 2 and the jackscrew 6 play a sealing role, so that the air tightness in the cover body 1 is ensured to be good. The tested air inlet valve 3 is arranged in the cover body 1, the tested air inlet valve 3 and the cover body 1 are pressed together through the compensation ring 7, the top of the tested air inlet valve 3 is in compression joint with the valve pressing cover 5, the jackscrew 6 compresses the valve seat of the tested air inlet valve 3 on the sealing gasket on the compensation ring 7 through the valve pressing cover 5, the compensation ring 7 is compressed on the sealing gasket placed at the protruding stage of the cover body 1, and good sealing performance of the tested air inlet valve 3 in the cover body 1 is ensured. The function of the compensating ring is to compensate for the diameter difference between the inlet valve under test and the cover 1 so that one test stand can be adapted to multi-sized inlet valve tests. The cover body 1 is internally provided with a pressing fork 4, the pressing fork 4 penetrates through a runner of the air inlet valve 3 to be connected with the valve plate, and the pressing fork 4 is mainly used for testing elastic force. The pressing fork 4 is provided with a pressing fork counterweight groove 25, and the counterweight groove 25 is used for placing counterweight weights. 2 displacement sensors A12 and B13 are arranged in the cover body 1, and are symmetrically arranged by taking the center of the air valve as an axis and are used for measuring the average displacement of the valve plate of the air inlet valve 3 to be measured. The outer side surface of the cover body 1 is provided with 2 pressure transmitters PB14 and PA15 and 2 temperature transmitters TB16 and TA17, and the pressure transmitters PB14 and PA15 are used for measuring the pressure and the temperature of the upper and lower air inlet valves in the test process. The bottom of the cover body 1 is provided with a lower exhaust pipe 10 and a lower exhaust valve 11, and the lower exhaust valve 11 is arranged on the lower exhaust pipe 10 in a threaded or welded mode.

The side of the cover body 1 is provided with an upper air inlet and outlet 9 and a lower air inlet 8, and a buffer tank R is arranged behind the air source and used for reducing pressure fluctuation of the air supply for the test. The air inlet pipeline of the upper air inlet and outlet port 9 is connected with an air source, a vortex shedding flowmeter 18, a regulating valve PRC-B21 and an electromagnetic valve SC24 are sequentially arranged on the air inlet pipeline of the upper air inlet and outlet port 9, wherein the regulating valve PRC-B21 is connected with an automatic pressure control system 1 of the upper space of the tested air inlet valve 3 to form a PRC-B pressure control system, the automatic pressure control system 1 is formed by a programmable controller PLC, a pressure transmitter PB14 and the regulating valve PRC-B21, the pressure transmitter PB14, the programmable controller PLC and the regulating valve PRC-B21 are sequentially connected, a pressure measurement signal of the pressure transmitter PB14 is transmitted to an analog input port AI of the PLC, compared with a pressure set value and calculated by PID, and a control output signal is transmitted to the regulating valve PRC-B21 by an analog output port AO of the PLC, so that the pressure control of the upper space of the air inlet valve 3 is realized. A solenoid valve SB23 and a rotor flow transmitter 19 are arranged on the outlet pipe of the upper inlet and outlet port 9, after which the gas is evacuated. The air inlet pipeline of the lower air inlet 8 is connected with an air source, se:Sub>A regulating valve PRC-A20 and an electromagnetic valve SA22 are arranged on the air inlet pipeline of the lower air inlet 8, wherein the regulating valve PRC-A20 is connected with an automatic pressure control system 2 of the lower space of the tested air inlet valve 3 to form se:Sub>A PRC-A pressure control system, and the automatic pressure control system 2 is formed by se:Sub>A pressure transmitter PA15 and the regulating valve PRC-A20. The pressure transmitter PA15, the programmable controller PLC and the regulating valve PRC-A20 are sequentially connected; the pressure measurement signal of the pressure transmitter PA15 is transmitted to an analog input port AI of the PLC, compared with the pressure set value and calculated by PID, and the control output signal is transmitted to the regulating valve PRC-A20 by an analog output port AO of the PLC, so that the pressure control of the lower space of the air inlet valve 3 is realized.

The upper industrial personal computer PC is connected with the programmable controller PLC through a communication port, as shown in fig. 2. The analog input AI of the PLC is respectively connected with a vortex shedding flowmeter 18, a rotor flow transmitter 19, 2 displacement sensors A12 and B13, 2 pressure transmitters PB14 and PA15 and 2 temperature transmitters TB16 and TA 17; analog output AO of the PLC is connected with 2 regulating valves PRC-A20 and PRC-B21; the on-off output DO is connected to the signal lines of the 3 solenoid valves SA22, SB23, and SC24, as shown in fig. 2. Analog quantity signals of all pressure, temperature, displacement sensors or transmitters and 2 flow transmitters are input into a programmable controller PLC through an analog input card, and the PLC outputs control output signals to 2 electric regulating valves through analog output cards respectively; and outputting on-off control signals to the 3 electromagnetic valves respectively.

The programmable controller PLC comprises two test programs, namely a leakage test boosting program and a dynamic performance boosting program; the pressure set point boost curve for the leak test boost program is shown in fig. 3. The boost slope K may be set, the boost times t1, t3, t5, t7 may be set, the settling times t2, t4, t6 may be set, and the highest pressure Pm may be set. The number of the boosting sections and the stabilizing sections is automatically calculated and determined by the PLC according to the set value. When the highest pressure is reached, the execution of other setting contents is stopped immediately; when the execution of other setting contents is finished, if the test pressure does not reach the highest pressure, the test pressure is boosted by the setting slope K until reaching the highest pressure Pm; the value of the highest pressure Pm of the dynamic performance boosting program is different from that of the leakage quantity boosting program, and the rest is the same. The two test programs are all in an automatic control mode, and are automatically executed according to a preset test program except for switching of the two test programs, so that manual intervention is not needed; and after the test is finished, automatically generating a test result and a test curve, and providing the functions of manual keyboard operation and human intervention in the process of program execution in order to increase the flexibility of the test.

PID control of the programmable controller PLC is output through a virtual regulator; the virtual regulators are built through domestic configuration software (king or MCGS), 2 virtual regulators are obtained, and an operable interface is built. The PLC controls the pressure automatic control systems 1 and 2. The 2 pressure control systems have double control functions of program control and operator keyboard control, namely, the test pressure set value has double functions of program boosting and operation boosting, so that the control output executes the automatic control output of the PLC or is switched into the manual keyboard operation output.

The air valve elastic force test requires that the total elastic force of the air valve formed by the air valve spring, the valve plate and the buffer plate in a self-elastic mode is known in advance when the air thrust coefficient is obtained. The invention adopts the whole actual measurement mode to obtain the elastic force of the air inlet valve, and is more accurate and reliable than the theoretical calculation result adopted by the existing blowing test. The actual measurement method is shown in the arrangement of FIG. 4. The pressure fork 4 is directly pressed onto the valve plate from a runner groove of the valve seat of the air inlet valve to be detected, the pressure fork 4 has no contact point with the valve seat of the air inlet valve to be detected, at the moment, the external force born by the valve plate has elastic force and the gravity of the pressure fork 4, the dead weight of the pressure fork 4 is known, weights are applied to a pressure fork counterweight groove 25 at the top of the pressure fork 4, the total weight change of the pressure fork causes the lifting height of the valve plate, namely the valve plate is pressed from the height of the valve seat to the height of the valve plate just reaching a lifting limiter, and the valve plate is read from output signals of the displacement sensor A12 and the displacement sensor B13; the linear precision of the domestic high-precision linear displacement sensor is 0.05%, and the accurate measurement requirement of valve plate lift can be met. If the fork placement is balanced, only one displacement sensor may be used. The total spring force-lift height correspondence curve can be obtained by changing the weight of the weights in the grooves 25. Within the maximum lift of the valve plate of the air valve, the more the measuring points are, the higher the accuracy of the elastic curve is. The height at which the valve plate is pressed off the valve seat and the height at which the valve plate just reaches the lift limiter require particularly accurate measurements. As shown in fig. 7. The thrust coefficient-lift height/seat seal face channel width curve can also be obtained in combination with the thrust coefficient calculation formula, as shown in fig. 8. Within the maximum lift of the valve plate of the air valve, the more the measuring points are, the higher the accuracy of the elastic curve is. The height at which the valve plate is pressed off the valve seat and the height at which the valve plate just reaches the lift limiter require particularly accurate measurements.

The leakage quantity is related to the pressure difference between the upper part and the lower part of the valve plate; the reciprocating compression and the air inlet valve are in actual work from the beginning to the end of the compression process, the pressure difference between the upper part and the lower part of the valve plate is changed, and the maximum value of the pressure difference is the pressure difference between the exhaust pressure and the inlet pressure of the cylinder.

The measuring the leakage comprises the steps of:

step A1: according to the equipment installed in fig. 5, the air inlet valve, the valve pressing cover and the displacement sensor to be tested are placed into the cover body respectively in sequence, the top cover is covered, the fastening bolts on the top cover and the cover body are screwed, the jackscrews are screwed into the screw thread in the center of the cover body, and the valve pressing cover compresses the valve seat on the compensation ring through the screwing of the jackscrews. Providing an air source with se:Sub>A pressure which is 15% -25% higher than the maximum working pressure of the air cylinder in practical application, using se:Sub>A displacement sensor A12, se:Sub>A displacement sensor B13, se:Sub>A pressure transmitter PB 14, se:Sub>A pressure transmitter PA 15, se:Sub>A temperature transmitter TB 16, se:Sub>A temperature transmitter TA 17 and se:Sub>A rotor flow transmitter 19, opening an electromagnetic valve SA22 and an electromagnetic valve SB23, closing se:Sub>A lower exhaust valve 11, closing an electromagnetic valve SC24, stopping se:Sub>A PRC-B pressure control system, starting the PRC-A pressure control system and setting PID parameters of se:Sub>A PLC loop virtual regulator;

step A2: starting a leakage quantity test boosting program switch of the air inlet valve, and starting a test program; the gas enters from the lower air inlet, the gas leaked from the valve plate of the tested air inlet valve is discharged from the upper air inlet and outlet, and finally the gas is discharged after being metered by the rotor flow transmitter. The test pressure is increased from zero to the maximum pressure of the cylinder, the set value of the PRC-A pressure control system is increased according to se:Sub>A preset leakage test boosting program, or se:Sub>A program setting program is cut off, keyboard operation is carried out, and the test pressure at the bottom of the test bed is changed by manually changing the set value of the boosting or directly changing the output of the regulating valve; the PLC receives the signal from pressure transmitter PA 15 and rotor flow transmitter 19 sends the leakage flow signal to the PLC, which depicts the corresponding leakage amount, pressure value as a leakage amount-differential pressure relationship, as shown in fig. 8. So far the intake valve leakage test is ended.

The leak amount-differential pressure relationship is shown in fig. 9, and the values are based on the pressure difference between the test bed pressures PA15 and PB 14. The rotor flow transmitter 19 selects a product with temperature and pressure compensation function, otherwise, the temperature and pressure transmitters are additionally arranged in front of the rotor flowmeter, and the temperature and pressure compensation algorithm is compiled by adopting the prior art, and the automatic compensation calculation is performed by a computer or a PLC. The dynamic performance of the valve plate refers to the corresponding relation among the upper and lower pressure differences of the valve plate, the lift of the valve plate and the flow velocity, the pressure difference between the upper and lower valve plates changes from the beginning to the end of the air suction process in the air suction section of the tested air inlet valve, the maximum value of the pressure difference is related to the instantaneous resistance coefficient of the air valve, and the specific value can be obtained in the following air valve pressure loss test.

The leak test pressure set point boost curve in this example is shown in fig. 3. The boost slope K may be set, the boost times t1, t3, t5, t7 may be set, the settling times t2, t4, t6 may be set, and the highest pressure Pm may be set. The number of the boosting sections and the stabilizing sections is automatically calculated and determined by the PLC according to the set value. When the highest pressure is reached, the execution of other setting contents is stopped immediately; when the execution of other setting contents is finished, if the test pressure does not reach the highest pressure, the pressure is increased by the setting slope K until reaching the highest pressure Pm.

The dynamic performance of the valve plate is the corresponding relation between the front and rear differential pressure of the valve plate, the lift of the valve plate and the flow velocity, the pressure difference of the air inlet valve in the air suction section is changed from the beginning to the end of the air suction process, the maximum value of the differential pressure is related to the instantaneous resistance coefficient of the air valve and is smaller than the absolute pressure value of the air inlet, and the specific value can be obtained in the following air valve pressure loss test.

The dynamic performance of the test valve plate comprises the following steps:

step B1: according to the equipment configuration operation of fig. 6, the tested air inlet valve, the valve pressing cover and the displacement sensor are respectively placed in the cover body in sequence, the top cover is covered, the fastening bolts on the top cover and the cover body are screwed, the jackscrews are screwed into the screw thread part in the center of the cover body, and the valve pressing cover compresses the valve seat on the compensation ring through the screwing of the jackscrews. Providing an air source with pressure which is 15% -25% higher than the highest pressure difference between the upper and lower valve plates, using a displacement sensor A12, a displacement sensor B13, a pressure transmitter PB 14, a pressure transmitter PA15, a temperature transmitter TB 16, a temperature transmitter TA17 and a vortex shedding flowmeter 18, closing an electromagnetic valve SA22 and an electromagnetic valve SB23, opening a lower exhaust valve 11, and opening an electromagnetic valve SC 24. The PRC-A20 pressure control system is deactivated, and the pressure control system in which the PRC-B21 is located is set and started. The air enters from the upper air inlet and outlet 9, passes through the tested air inlet valve and is exhausted by the lower air exhaust pipe 10.

Step B2: and starting a boost program switch for dynamic performance test of the air inlet valve, and starting the dynamic test program to run. The test pressure Pm is 110% of the upper and lower maximum pressure difference of the valve plate in actual working, the set value of the PRC-B pressure control system is boosted according to a dynamic performance boosting program or is set by a cutting program, the keyboard operation is carried out, and the boosting set value is manually changed or the test pressure at the upper part of the test bed is directly changed by changing the output of the regulating valve. The PLC receives signals output by the pressure transmitter PB14, the vortex shedding flowmeter 18 sends air inlet flow signals to the PLC, the displacement sensor A12 and the displacement sensor B13 send valve sheet lift signals to the PLC, and the PLC draws corresponding air inlet pressure, air inlet flow, average values of the displacement sensor A12 and the displacement sensor B13 into a valve sheet pressure difference-valve sheet lift and flow velocity relation curve. If necessary, the pressure can be manually increased at a specific pressure or a specific position of the valve plate to obtain special data. For example, to obtain accurate pressure, flow and other data of the valve plate moving away from and reaching the valve seat or the lift limiter, the pressure can be finely adjusted by adopting a manual adjustment mode to obtain required data. And the dynamic performance test of the air inlet valve is finished.

The valve plate differential pressure-valve plate lift and flow velocity relation curve is shown in fig. 10, and the differential pressure takes the difference value of the test bed pressures PB14 and PA15 as the standard. The vortex shedding flowmeter 18 should select a product with temperature and pressure compensation functions.

The performance parameters that can be calculated according to the above test procedure are: the specific calculation process of the standard state volume leakage flow, valve plate lift position, valve gap Mach number, flow coefficient, thrust coefficient, effective flow area, resistance coefficient and pressure loss under different valve plate pressure differences is as follows:

(1) Calculation of valve gap Mach number

Wherein:

M _max -maximum mach number of valve gap flow;

v _Fmax -maximum flow rate of valve gap flow;

a- -the sonic velocity of the gas.

The maximum flow velocity v of the system is obtained by _Fmax And gas sonic velocity a.

Wherein:

A _p -piston area;

v _max -the highest displacement speed of the suction section piston;

n is the number of air inlet valves on the same side of the cylinder;

a _Vmax -maximum valve clearance area;

α _V(max) valve gap flow coefficient corresponding to the maximum valve gap area.

Formula (2) has alpha _V(max) 、a _Vmax 、v _max 3 parameters to be solved.

a _V ＝lh--------(3)

Wherein:

a _V -valve gap area;

l- -the measured total edge length of the valve seat ring groove;

h- -valve plate lift.

Wherein:

α _v -valve gap flow coefficient;

q _v volumetric flow, i.e. the flow measured by a vortex shedding flowmeter;

ρ _W -the operating density of the gas before the valve;

ΔP- -the difference between the gas pressure before and after the valve, i.e., the pressure difference between the pressures measured by test stand PB14 and PA 15.

Wherein:

P _B air inlet pressure, i.e. the pressure measured by test stand PB 14;

P _N standard atmospheric pressure, i.e. 0.10135MPa;

T _B -pre-valve gas temperature, i.e. testA temperature measured by the table TB 16;

T _N -standard temperature, i.e. 273.15K;

ρ _N -the standard density of the test gas.

In the dynamic performance test process of the test bed, the valve plates are positioned at different lift positions and correspond to different volume flows, valve clearance areas, pre-valve gas working condition densities and pressure differences. When the valve plate is at the maximum lift position, the maximum valve clearance area a of the air valve can be obtained according to the formula 3 _Vmax Collecting data by a test bed, and calculating according to formulas 4 and 5 to obtain a valve clearance flow coefficient alpha corresponding to the maximum valve clearance area _V(max) 。

Wherein:

v—the speed of movement of the suction section piston;

r- -crank radius;

omega- -compressor angular velocity;

λ—the ratio of crank radius to connecting rod length;

θ -crank angle.

Differentiating the crank angle by equation 6, i.e

When (when)

Crank angle θ at which maximum thrust is obtained _m Will be theta _m Substituting formula 6 to obtain maximum moving speed v of the suction section piston _max 。

Wherein:

k- -gas Heat insulation indexTypically 1.66 for monoatomic gas, 1.41 for diatomic gas, and 1.29 for polyatomic gas; r is R _g -the gas constant of the compressed gas.

Wherein:

r-universal gas constant, r= 8314.5J/mol;

M _mol -relative molar mass of compressed gas

To this end (1) the maximum Mach number M of the valve gap can be obtained _max Is calculated by the computer.

(2) Calculation of thrust coefficient

Wherein:

beta-thrust coefficient;

F _g -gas force;

a _e -the flow area of the outflow side of the valve seat;

P _B air inlet pressure, i.e. the pressure measured by test stand PB 14;

P _A in-cylinder pressure, i.e. the pressure measured by the test bench PA 15.

In the performance test process of the air inlet valve, when the dynamic performance boosting program runs in the stable time periods t2, t4 and t6, the pressure of the upper part of the air inlet valve to be tested of the test bed is controlled to be a relatively stable pressure value under the control of the pressure control loop PRC-B, and the air thrust and the elastic force on the valve plate are balanced at the moment, namely F _s ＝F _g The average value of the 2

position sensors

12 and 13 is read out, and the corresponding spring force F is automatically detected from the spring force-lift curve obtained from the valve spring force test _s The thrust coefficient calculation formula (10) is changed to formula (11). Meanwhile, the PLC calculates the average value of the pressure difference between PB14 and PA15 in the last 10 seconds of the period, namely P of (11) _B -P _A 。

Therefore, the thrust coefficient at different lifts can be calculated, and finally the thrust coefficient is converted into a curve of beta-h/b.

(3) Calculation of flow coefficient and valve clearance effective flow area

A＝α _v a _v --------(12)

Wherein:

a- -the effective flow area of the valve;

α _v -the valve gap flow coefficient of the gas valve, obtainable from equation 4;

a _v the valve clearance flow area of the valve is obtained from equation 3.

As can be seen from 5.1, when the valve plate is located at different lift positions, the valve clearance area a of the valve corresponding to the different lift positions can be obtained according to the formula 3 _v Collecting data by a test bed, and calculating according to formulas 4 and 5 to obtain valve clearance flow coefficient alpha corresponding to the valve clearance area _v The effective flow area a of the valve lash corresponding to the different lift positions is obtained according to equation 12.

(4) Calculation of drag coefficient and pressure loss

Wherein:

ζ - -resistance coefficient;

g- -gravitational acceleration;

ΔP- -the pressure difference between the gas before and after the valve, i.e., the pressure difference between the pressures measured by test stand PB14 and PA 15;

v _F -valve clearance speed;

ρ _W -pre-valve gas regime density, obtainable from equation 5;

wherein:

q _v volumetric flow, i.e. the flow measured by a vortex shedding flowmeter;

a _v the valve clearance flow area of the valve is obtained from equation 3.

The pressure loss is the permanent loss of the pressure of the fluid passing through the valve plate, namely the pressure difference delta P between the front and the back of the air valve, and the pressure loss is equal to the difference between the measured pressure values of PB14 and PA 15.

The data of the invention are all obtained by tests, including the acquisition of the elastic force of the air valve, by experimental methods instead of theoretical calculation of the elastic force used in the existing air blowing test. The reality of the elastic force has the greatest influence on the result of the thrust coefficient of the air valve, the calculation error of the elastic force is large, the deviation between the actual value of the shear modulus of the spring material and the designed value is caused, the manufacturing error of the spring structure, winding and heat treatment is caused, and the calculation error of the self-elasticity of the net-shaped valve plate and the buffer plate is caused. Therefore, the elastic force of the air valve is measured by an experimental method to be of practical significance.

The gas used in the test of the invention can be air or all non-toxic and non-flammable gases, and the test contents are as follows: differential pressure of different valve plates: the flow coefficient, the thrust coefficient, the effective flow area, the resistance coefficient and the pressure loss corresponding to the standard state volume leakage flow, the valve plate lift position and the valve gap Mach number.

The invention only needs the basic design data of the known tested air inlet valve: the design data of the air valve such as the appearance installation dimension, the maximum lift of the valve plate, the flow area of the outflow side of the valve seat, the total side length of the flow channel groove, the pressure before and after the valve of the tested air valve, the rated flow, the compression medium composition and the like. If the measured air valve does not have the structural data, the measured air valve needs to be disassembled for actual mapping. The invention is used for simulating and calculating the motion rule of the valve plate under the rated working condition, and the following steps are needed: motor speed, cylinder bore, cylinder working stroke, number of intake valves at the present stage, total clearance volume of the cylinder, crank radius, connecting rod length, and rated displacement and rated discharge pressure of the compressor.

According to the elastic force test and dynamic performance test results, the invention can also simulate and calculate the valve plate movement law under the rated working condition of the practical compressor, and the specific calculation process is as follows:

(1) Calculation of macroscopic motion trail of valve plate of suction section under rated working condition

The rated working condition mainly refers to rated pressure and rated discharge capacity of the reciprocating compressor. In the elastic force test, the elastic force of the valve plate at the lift limiter position can be obtained. If the gas thrust can be larger than or equal to the elastic force under the rated working condition, the valve plate can reach the lift limiter, and the time from the moment that the thrust is larger than the elastic force to the moment that the thrust is smaller than the elastic force is the stay time of the valve plate at the maximum opening; if the gas thrust is constantly smaller than the elastic force, the valve plate cannot reach the lift limiter, and the residence time of the valve plate at the maximum opening degree is zero.

The motion trail of the valve plate of the air suction section refers to a curve of the whole air suction section describing the corresponding relation between the lift position and time of the valve plate; the macroscopic motion track is a complex motion phenomenon such as valve plate rolling, flutter and rebound generated by collision of the valve plate with the valve seat and the lift limiter without considering fluctuation of air flow and elastic force.

In the dynamic test, a corresponding relation curve of the valve plate lift position and the air inlet flow is established, so that the calculation aim is to establish a functional relation between the rotation angle and the air inlet flow. Knowing the intake air flow corresponding to a certain lift position of the valve plate, the motion speed of the piston can be obtained by using the formula (15), and the numerical solution of the crank angle can be obtained by using excel or MATLAB calculation according to the formula (16). The dynamic test results and (15), (16) and (17) are utilized to calculate the relative time of the valve plate in any lift position in the air suction process, and the macroscopic motion track 'lift position-time' curve of the valve plate can be drawn.

v＝4Q/(π×D ² )-----------------------------(15)

In the middle of

v: the speed of the movement of the piston,

q: the flow rate of the intake air,

d, a step of performing the process; cylinder inside diameter.

The movement speed of the piston in the suction process is shown as (16), 2 corners correspond to the same piston speed in the suction section, and if the instantaneous flow of the valve plate reaching the lift limiter is substituted into the formula (15), the obtained time between the two corners is the time of the valve plate staying on the lift limiter, namely the maximum opening staying time.

(3) Calculation of valve plate opening lag time under rated working condition

The opening lag time refers to the time difference between the actual opening time and the theoretical opening time of the air inlet valve. The theoretical valve opening moment of the air inlet valve is when the thrust of the air to the valve plate is equal to zero, and the actual valve opening moment is when the thrust of the air to the valve plate is equal to the elastic force, and the theoretical valve opening moment of the air inlet valve is when the expansion section of the compressor is ended, and certain delay exists between the theoretical valve opening moment and the actual valve opening moment.

The actual valve opening time t of the air valve is carried out _o According to the characteristic that the gas thrust is equal to the elastic force at the moment, firstly, calculating the pressure p of the gas in the cylinder at the moment by the method (18) ₀ Then, the volume V of the gas in the cylinder at the moment is calculated by (19) ₀ Then calculate the displacement x of the piston at that time from (20) ₀ Calculating the crank angle θ from (21) _o Further, the actual valve opening time t is calculated by (22) _o 。

F _so ＝F _go ＝β ₀ a _e (p _s -p _o )--------(18)

Wherein the method comprises the steps of

m- -expansion index, values according to Table 1:

TABLE 1 expansion index m value table

Range of intake pressure	m takes on value	Range of intake pressure	n is a value
				p _s ≤0.15MPa	1+0.5(k-1)	1.0≤p _s ≤3.0MPa	1+0.88(k-1)
0.15≤p _s ≤0.40MPa	1+0.62(k-1)	p _s ≥3.0MPa	k
				0.40≤p _s ≤1.0MPa	1+0.75(k-1)

F _so -the elastic force of the valve when it is about to open;

F _go -gas force when the gas valve is about to open;

β ₀ thrust coefficient when valve plate is stopped at valve seat, beta ₀ ＝1.0；

a _e -the flow area of the outflow side of the valve seat;

p _s -nominal intake pressure;

p _o -in-cylinder pressure when the gas valve is closed and is about to open.

V _o -the upper volume of the piston when the gas valve is about to open;

V _y -cylinder clearance volume;

p ^d -rated exhaust pressure;

x _o -the instantaneous displacement of the piston when the gas valve is about to open;

d—cylinder bore.

θ _o -crank angle at which the gas valve will open;

r- -crank radius;

lambda-ratio of crank radius to connecting rod length.

t _o -the actual valve opening moment of the gas valve;

t-compression period.

The theoretical valve opening time is that the pressure of the gas in the cylinder is equal to the inlet pressure, and the volume V of the gas in the cylinder at the moment is calculated by (23) _s Then calculating theoretical valve opening time according to the formulas (24), (25) and (26), and finally calculating the lag time delta t of the actual valve opening according to the formula (27) ₂ 。

△t ₂ ＝t _o -t _s --------(27)

Wherein:

V _s -the piston upper volume at the end of the expansion section;

V _y -cylinder clearance volume;

p _d -rated exhaust pressure;

p _s -nominal intake pressure;

x _s -the instantaneous displacement of the piston at the end of the expansion section;

θ _s -crank angle at the end of the expansion section;

t _s -theoretical opening moment of the air valve;

t _o -the actual valve opening moment of the gas valve;

t—compression period;

△t ₂ -lag time for valve opening.

The test bed tests the air medium, and if the air medium is different from the gas parameter properties such as the gas density of the actual compressed gas, the performance test result can be the corresponding result of the actual compressed gas. The scaling mainly involves the scaling of the following formulas:

(1) Valve gap Mach number

Wherein:

M _ymax -the valve gap mach number of the actual compressed gas;

M _max -the valve gap mach number of the test air is calculated from equation 1;

k- -the gas insulation index of the test air, 1.6 air;

k _y the gas adiabatic index of the actual compressed gas, typically 1.66 for monoatomic gas, 1.41 for diatomic gas, and 1.29 for polyatomic gas;

R _gy -the gas constant of the actual compressed gas is calculated from equation 9;

R _g the gas constant of the test air was 287.11.

(2) Flow coefficient and valve clearance effective flow area

A _y ＝α _vy a _v --------(30)

Wherein:

α _vy -valve gap flow coefficient of the actual compressed gas;

α _v -valve gap flow coefficient of test air, calculated by equation 4;

ρ _W the working condition density of the air for the test before the valve is calculated by a formula 5;

ρ _Wy the working condition density of the actual compressed gas before the valve is calculated by the formula 5;

A _y -the effective flow area of the valve gap of the actual compressed gas;

a _v the valve gap flow area of the valve is calculated by equation 3.

(3) Coefficient of resistance

Wherein:

ζ - -the resistance coefficient of the test air, calculated from equation 13;

ξ _y -the drag coefficient of the actual compressed gas.

The foregoing description is only of the preferred embodiments of the present disclosure and description of the principles of the technology being employed. It will be appreciated by those skilled in the art that the scope of the invention in the embodiments of the present disclosure is not limited to the specific combination of the above technical features, but encompasses other technical features formed by any combination of the above technical features or their equivalents without departing from the spirit of the invention. Such as the above-described features, are mutually substituted with (but not limited to) the features having similar functions disclosed in the embodiments of the present disclosure.

Claims

1. The full-automatic multifunctional test bed for the net-shaped air inlet valve of the reciprocating compressor is characterized by comprising a cover body 1, a top cover 2, an air inlet valve to be tested 3, a pressure fork 4, a pressure valve cover 5, a jackscrew 6, a vortex shedding flowmeter 18, a rotor flow transmitter 19, 2 displacement sensors A12 and B13, 2 pressure transmitters PB14 and PA15, 2 temperature transmitters TB16 and TA17, 2 regulating valves PRC-A20 and PRC-B21, 3 electromagnetic valves SA22, SB23 and SC24, an upper industrial personal computer PC and a programmable controller PLC;

The top of the cover body 1 is fixed with the top cover 2 through a plurality of fastening bolts, a jackscrew 6 is arranged at the center of the top cover 2, a tested air inlet valve 3 is arranged in the cover body 1, the tested air inlet valve 3 and the cover body 1 are in compression sealing through a compensation ring 7, the top of the tested air inlet valve 3 is compressed through a valve pressing cover 5, the jackscrew 6 compresses a valve seat of the tested air inlet valve 3 on a sealing gasket on the compensation ring 7 through the valve pressing cover 5, the compensation ring 7 is compressed on the sealing gasket placed at a boss stage of the cover body 1, a pressing fork 4 is arranged in the cover body 1, the pressing fork 4 passes through a runner of the air inlet valve 3 to be contacted with a valve plate, a pressing fork counterweight groove 25 is formed in the pressing fork 4, 2 displacement sensors A12 and B13 are arranged in the cover body 1 and are axially symmetrically arranged by taking the center of the air valve, 2 pressure transmitters PB14 and PA15 and 2 temperature transmitters TB16 and TA17 are arranged on the outer side surface of the cover body 1, a lower exhaust pipe 10 and a lower exhaust valve 11 are arranged at the bottom of the cover body 1, and the lower exhaust valve 11 is arranged on a lower exhaust pipe 10 in a threaded or welded mode;

an upper air inlet and outlet 9 and se:Sub>A lower air inlet 8 are formed in the side face of the cover body 1, se:Sub>A buffer tank R is arranged behind an air source, an air inlet pipeline of the upper air inlet and outlet 9 is connected with the air source, se:Sub>A vortex shedding flowmeter 18, se:Sub>A regulating valve PRC-B21 and an electromagnetic valve SC24 are sequentially arranged on the air inlet pipeline of the upper air inlet and outlet 9, the regulating valve PRC-B21 is connected with se:Sub>A pressure automatic control system 1 to form se:Sub>A PRC-B pressure control system, the pressure automatic control system 1 is formed by se:Sub>A programmable controller PLC, se:Sub>A pressure transmitter PB14 and se:Sub>A regulating valve PRC-B21, signal lines of the pressure transmitter PB14, the programmable controller PLC and the regulating valve PRC-B21 are sequentially connected, an electromagnetic valve SB23 and se:Sub>A rotor flow transmitter 19 are arranged on the air outlet pipeline of the upper air inlet and outlet 9, the air inlet pipeline of the lower air inlet 8 is connected with the air source, the regulating valve PRC-A20 and the electromagnetic valve SA22 are arranged on the air inlet pipeline of the lower air inlet 8, the regulating valve PRC-A20 is connected with the pressure automatic control system 2 to form se:Sub>A PRC-A pressure control system, and the pressure automatic control system 2 is formed by the pressure automatic control system pse:Sub>A 15 and the pressure transmitter PA15 and the regulating valve 20 is formed by the pressure transmitter 20; the signal lines of the pressure transmitter PA15, the programmable controller PLC and the regulating valve PRC-A20 are sequentially connected;

The upper industrial personal computer PC is connected with the programmable controller PLC through a communication port, and an analog input AI of the PLC is respectively connected with signal lines of the vortex shedding flowmeter 18, the rotor flow transmitter 19, 2 displacement sensors A12 and B13, 2 pressure transmitters PB14 and PA15 and 2 temperature transmitters TB16 and TA 17; analog quantity output AO of the PLC is connected with signal lines of 2 regulating valves PRC-A20 and PRC-B21; the on-off output DO is connected to the signal lines of the 3 solenoid valves SA22, SB23 and SC 24.

2. The full-automatic multifunctional test bed of the reticular air inlet valve of the reciprocating compressor according to claim 1, wherein the upper industrial personal computer PC comprises a display, a man-machine interface, test result processing and a test curve and test table generating function, and the printer prints the test result and the test curve; the test result and the test curve are established by using domestic configuration software; the test curves comprise an elastic force-valve plate lift curve, a thrust coefficient-h/b curve, a valve clearance flow coefficient-h/b curve, a valve plate lift-standard state volume flow curve, a relative pressure loss-valve clearance Mach number curve and relation curves required among all test parameters; and setting parameters, displaying a human-computer interface, starting, stopping and printing on the upper computer.

3. The full-automatic multifunctional test bed of the net-shaped air inlet valve of the reciprocating compressor according to claim 1, wherein the PID control of the programmable controller PLC is output through a virtual regulator; the virtual regulators are built through domestic configuration software, 2 virtual regulators are obtained, and an operable interface is built; the PLC controls the pressure automatic control systems 1 and 2; the 2 pressure control systems have double control functions of program control and operator keyboard control, namely, the test pressure set value has double functions of program boosting and operation boosting, so that the control output executes the automatic control output of the PLC or is switched into the manual keyboard operation output.

4. The full-automatic multifunctional test stand of a reciprocating compressor mesh air inlet valve according to claim 1, wherein the programmable controller PLC comprises two test programs, namely a leakage test boosting program and a dynamic performance boosting program; in the leakage quantity test boosting program, the quantity of the boosting sections and the voltage stabilizing sections is automatically calculated and determined by the PLC according to the set value; when the highest pressure is reached, the execution of other setting contents is stopped immediately; when the execution of other setting contents is finished, if the test pressure does not reach the highest pressure, the test pressure is boosted by the setting slope K until reaching the highest pressure Pm; the value of the highest pressure Pm of the dynamic performance boosting program is different from that of the leakage quantity boosting program, and the rest is the same; the two test programs are all in an automatic control mode, and are automatically executed according to a preset test program except for switching of the two test programs, so that manual intervention is not needed; and after the test is finished, automatically generating a test result and a test curve, and providing the functions of manual keyboard operation and human intervention in the process of program execution.

5. The full-automatic multifunctional test method for the net-shaped air inlet valve of the reciprocating compressor is realized based on the full-automatic multifunctional test bed for the net-shaped air inlet valve of the reciprocating compressor according to the claim 1, and is characterized by comprising an air inlet valve elastic force test, a leakage amount measurement, a dynamic performance of a test valve plate, a basic performance calculation method of the tested air inlet valve and a simulation calculation method of a macroscopic motion rule of the valve plate under a rated working condition;

The measuring the leakage comprises the steps of:

step A1: the tested air inlet valve, the valve pressing cover and the displacement sensor are respectively placed in the cover body in sequence, the top cover is covered, the fastening bolts on the top cover and the cover body are screwed, the jackscrews are screwed into the screw thread in the center of the cover body, and the valve pressing cover compresses the valve seat on the compensation ring through the screwing of the jackscrews; providing an air source with se:Sub>A pressure which is 15% -25% higher than the maximum working pressure of the air cylinder in practical application, using se:Sub>A displacement sensor A12, se:Sub>A displacement sensor B13, se:Sub>A pressure transmitter PB 14, se:Sub>A pressure transmitter PA 15, se:Sub>A temperature transmitter TB 16, se:Sub>A temperature transmitter TA 17 and se:Sub>A rotor flow transmitter 19, opening an electromagnetic valve SA22 and an electromagnetic valve SB23, closing se:Sub>A lower exhaust valve 11, closing an electromagnetic valve SC24, stopping se:Sub>A PRC-B pressure control system, starting the PRC-A pressure control system and setting PID parameters of se:Sub>A PLC loop virtual regulator;

step A2: starting a leakage quantity test boosting program switch of the air inlet valve, and starting a test program; the gas enters from the lower air inlet, the gas leaked from the valve plate of the air inlet valve to be tested is discharged from the upper air inlet and outlet, and the gas is finally measured by the rotor flow transmitter and then is discharged; the test pressure is increased from zero to the maximum pressure of the cylinder, the set value of the PRC-A pressure control system is increased according to se:Sub>A preset leakage test boosting program, or se:Sub>A program setting program is cut off, keyboard operation is carried out, and the test pressure at the bottom of the test bed is changed by manually changing the set value of the boosting or directly changing the output of the regulating valve; the PLC receives the signal output by the pressure transmitter PA 15, the rotor flow transmitter 19 sends the leakage flow signal to the PLC, and the PLC draws the corresponding leakage amount and pressure value into a leakage amount-differential pressure relation curve, so that the leakage amount test of the air inlet valve is finished;

The value of the leakage quantity-differential pressure relation curve is based on the pressure difference value of the test bed pressures PA15 and PB 14;

the dynamic performance of the test valve plate comprises the following steps:

step B1: the tested air inlet valve, the valve pressing cover and the displacement sensor are respectively placed in the cover body in sequence, the top cover is covered, the fastening bolts on the top cover and the cover body are screwed, the jackscrews are screwed into the screw thread in the center of the cover body, and the valve pressing cover compresses the valve seat on the compensation ring through the screwing of the jackscrews; providing an air source with pressure which is 15% -25% higher than the highest pressure difference between the upper and lower valve plates, using a displacement sensor A12, a displacement sensor B13, a pressure transmitter PB14, a pressure transmitter PA15, a temperature transmitter TB 16, a temperature transmitter TA 17 and a vortex shedding flowmeter 18, closing an electromagnetic valve SA22 and an electromagnetic valve SB23, opening a lower exhaust valve 11, and opening an electromagnetic valve SC 24; deactivating the PRC-A20 pressure control system, setting and starting the pressure control system where the PRC-B21 is positioned; the gas enters from the upper gas inlet and outlet 9, passes through the tested gas inlet valve and is exhausted by the lower gas exhaust pipe 10;

step B2: starting a boost program switch for dynamic performance test of the air inlet valve, and starting a dynamic test program to run; the test pressure Pm is 110% of the upper and lower maximum pressure difference of the valve plate in actual working, the set value of the PRC-B pressure control system is boosted according to a dynamic performance boosting program or is set by a cutting program, keyboard operation is carried out, and the boosting set value is manually changed or the test pressure at the upper part of the test bed is directly changed by changing the output of the regulating valve; the PLC receives signals output by the pressure transmitter PB14, the vortex shedding flowmeter 18 sends air inlet flow signals to the PLC, the displacement sensor A12 and the displacement sensor B13 send valve sheet lift signals to the PLC, and the PLC draws corresponding air inlet pressure, air inlet flow, average values of the displacement sensor A12 and the displacement sensor B13 into valve sheet pressure difference-valve sheet lift and flow velocity relation curves, so that the dynamic performance test of the air inlet valve is finished;

6. The full-automatic multifunctional test method of the mesh air inlet valve of the reciprocating compressor according to claim 5, wherein the dynamic performance of the valve plate is the corresponding relation between the differential pressure between the front and the rear of the valve plate, the lift of the valve plate and the flow velocity, the pressure difference between the front and the rear of the valve plate in the air suction section is changed from the beginning to the end of the air suction process, the maximum value of the differential pressure is related to the instantaneous resistance coefficient of the air valve and is smaller than the absolute pressure value of the air inlet.

7. The full-automatic multifunctional test method for the net-shaped air inlet valve of the reciprocating compressor according to claim 5, wherein the basic performance calculation method for the tested air inlet valve comprises the steps of valve gap Mach number calculation, thrust coefficient calculation, flow coefficient and valve gap effective flow area calculation, resistance coefficient calculation and pressure loss calculation;

(1) Calculation of valve gap Mach number:

formula (2) has alpha _V(max) 、a _Vmax 、v _max 3 parameters to be solved;

a _V ＝lh--------(3)

Differentiating the crank angle by equation 6, i.e

When (when)

(2) Calculating a thrust coefficient:

in the test process of the performance of the air inlet valve, when the dynamic performance boosting program runs in the stable time periods t2, t4 and t6, under the control of the pressure control loop PRC-B, the pressure of the upper part of the air inlet valve to be tested of the test bed is controlled to be a relatively stable pressure value, and the air thrust and the elastic force on the valve plate are balanced at the moment, namely F _s ＝F _g The average value of the 2 position sensors 12 and 13 is read out, and the corresponding spring force F is automatically detected from the spring force-lift curve obtained from the valve spring force test _s Changing the thrust coefficient calculation formula (10) to formula (11); meanwhile, the PLC calculates the average value of the pressure difference between PB14 and PA15 in the last 10 seconds of the period of time, namely (11);

A＝α _v a _v --------(12)

as can be seen from the description of 5.1,when the valve plate is positioned at different lift positions, the valve clearance area a of the air valve corresponding to the different lift positions can be obtained according to the formula 3 _v Collecting data by a test bed, and calculating according to formulas 4 and 5 to obtain valve clearance flow coefficient alpha corresponding to the valve clearance area _v Obtaining valve clearance effective flow areas A corresponding to different lift positions according to a formula 12;

(4) Calculation of drag coefficient and pressure loss:

wherein: q _v Volumetric flow, i.e. the flow measured by a vortex shedding flowmeter; a, a _v -the valve clearance flow area of the valve, obtainable from equation 3;

When the front and rear temperatures of the air inlet valve are fixed, the valve gap doherty is calculated, the valve gap flow rate is directly calculated by an air inlet flow rate in a four-parameter relation curve established by the dynamic performance test of the air inlet valve through a calculation formula (2), and if the actual use pressure and temperature in front of the air inlet valve are different from the test pressure PB-14 and the test temperature TB-16, the compensation calculation is carried out by using a conventional pressure and temperature compensation technology; according to the thrust coefficient calculation method, a four-parameter relation curve established by an air inlet valve plate elastic force test and an air inlet valve dynamic performance test is directly used, the air thrust is replaced by elastic force corresponding to the same flow, and calculation is performed through a calculation formula (6); the flow coefficient calculating methodBy directly using the intake flow q in a four-parameter relation established by the dynamic performance test of the intake valve _v And the front-back pressure difference of the air inlet valve, and the flow coefficient alpha is calculated by a calculation formula (7) _v The method comprises the steps of carrying out a first treatment on the surface of the The resistance coefficient calculating method directly uses the calculation result of the flow coefficient to calculate the resistance coefficient through a calculation formula (10); the pressure loss calculation method directly uses the air inlet flow q in a four-parameter relation curve established by the dynamic performance test of the air inlet valve _v And the pressure difference between the front and the rear of the air inlet valve is calculated by the conventional temperature and pressure compensation technology and corresponds to the pressure difference between PB-14 and PB-15 in the test curve, and the pressure difference is the pressure loss at that time.

8. The full-automatic multifunctional test method for the net-shaped air inlet valve of the reciprocating compressor according to claim 5, wherein the simulation calculation method for the macroscopic motion law of the valve plate under the rated working condition is a method for establishing a time function of the lift height or the crank angle of the valve plate of the air suction section of the compressor, and comprises a simulation calculation method for the macroscopic motion trail of the valve plate, a simulation calculation method for the residence time of the maximum opening of the valve plate and a simulation calculation method for the opening lag time of the valve plate under the rated working condition;

v＝4Q/(π×D ² )-----------------------------(15)

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V-piston movement speed, Q-air inlet flow and D-cylinder inner diameter;

(3) Calculation of valve plate opening lag time under rated working condition

the actual valve opening time t of the air valve is carried out _o According to the characteristic that the gas thrust is equal to the elastic force at the moment, firstly, calculating the pressure p of the gas in the cylinder at the moment by the method (18) ₀ Then, the volume V of the gas in the cylinder at the moment is calculated by (19) ₀ Then calculate the displacement x of the piston at that time from (20) ₀ Calculating the crank angle θ from (21) _o Further, the actual valve opening time t is calculated by (22) _o ；

F _so ＝F _go ＝β ₀ a _e (p _s -p _o )--------(18)

the theoretical valve opening time is that the pressure of the gas in the cylinder is equal to the inlet pressure, and the volume V of the gas in the cylinder at the moment is calculated by (23) _s Then calculating theoretical valve opening time according to the formulas (24), (25) and (26), and finally calculating the lag time delta t of the actual valve opening according to the formula (27) ₂ ；

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△t ₂ ＝t _o -t _s --------(27)