Pressure testing device for plunger pair liquid film of high-pressure plunger pump

Abstract

The invention discloses a plunger pair liquid film pressure testing device for a high-pressure plunger pump. The plunger pair liquid film pressure testing device comprises a testing cavity assembly, a liquid film pressure testing assembly and a signal acquisition module. The testing cavity assembly is connected with a high-pressure plunger pump plunger pair, positions a plunger cavity to be tested and drains liquid in the plunger cavity to be tested to the multiple liquid film pressure testing assemblies. The plurality of liquid film pressure test assemblies respectively collect liquid film pressure signals of a plurality of plunger axial set points between plunger pairs of the high-pressure plunger pump. And the signal acquisition module extracts each liquid film pressure signal to obtain the liquid film pressure of each set point position in the axial direction of the plunger. According to the invention, the dead volume of the pressure sensor cavity can be effectively adjusted, the liquid film cavity can be amplified, the axial liquid film pressure between the plunger pairs can be obtained through testing, residual air in the sensor cavity can be discharged, the static pressure cavity is ensured to be filled with the liquid film, and accurate extraction of the liquid film pressure is realized.

Description

Technical Field

[0001] The invention relates to a device for testing the plunger auxiliary liquid film pressure of a high-pressure plunger pump, belonging to the technical field of fluid testing. Background Art

[0002] High-pressure plunger pumps are widely used in the aerospace field. For high-pressure plunger pumps, when working at high pressure, due to factors such as assembly errors, there are assembly errors between the plunger and the cavity, and the liquid film pressure between the cavity and the gap is unevenly distributed, with contact areas and film-forming areas. The contact area causes the plunger to wear, and long-term running-in causes the plunger surface to be worn and peeled off, which increases leakage and causes work failure in severe cases. In addition, the degree of plunger wear is positively correlated with the size of the liquid film pressure. In order to analyze whether the plunger pair surface is in a wear or film-forming state, the liquid film pressure between the plunger pairs needs to be tested. Therefore, it is necessary to design a high-pressure plunger pump plunger pair liquid film pressure test device to reveal the size of the liquid film pressure between the plunger pairs through this device.

[0003] In the paper "Study on the Characteristics of Micro-motion and Lubricating Oil Film of the Plunger Pair of Axial Piston Pump", a plunger pair liquid film pressure test method is proposed, and the analog test signal is extracted through the pressure sensor and the signal acquisition card. The specific principle is to drill a drainage hole in the surface of the cavity, and the liquid flows along the drainage hole from the plunger surface to the inner hole end face of the differential pressure sensor. The working pressure of the pressure sensor end face can be directly tested. However, it is suitable for testing the plunger pair liquid film pressure range not higher than 15MPa. The lower liquid working pressure makes the liquid film thickness between the plunger and the cavity larger, ensuring that the liquid flows into and fills the inner hole in the pressure sensor cavity, ensuring the extraction of the plunger pair liquid film pressure signal.

[0004] In high-pressure working environments, there is a large shear force between the plunger and the cavity, which leads to significant friction, heat and expansion, forming a small gap and high damping, thereby reducing the flow characteristics of the liquid film and failing to ensure that the fluid flows completely into the sensor cavity, resulting in deviations in the extraction of the liquid film pressure test signal. Although the cavity structure of the traditional differential pressure sensor can be improved and specifically manufactured to achieve micro-volume liquid film testing, the micro-volume required to be installed in the narrow space of the plunger cavity and the high-precision grinding silicon diaphragm are extremely expensive and cannot be mass-produced in the short term. There is no suitable high-pressure plunger pump plunger auxiliary liquid film pressure test device. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, and without losing the working principle characteristics of the plunger pump, a high-pressure plunger pump plunger auxiliary liquid film pressure testing device is proposed, especially under the condition of low plunger speed, the dead volume of the pressure sensor cavity is effectively reduced, the liquid film cavity is enlarged, and the accurate measurement of the liquid film pressure at each set point on the plunger axis is realized.

[0006] The technical solution of the present invention is:

[0007] A high-pressure plunger pump plunger auxiliary liquid film pressure test device, comprising a test cavity component, a liquid film pressure test component and a signal acquisition module;

[0008] The test chamber assembly is connected to the plunger pair of the high-pressure plunger pump, and the liquid film pressure between the positioning plunger and the plunger chamber is formed. The plunger reciprocates, and the liquid film pressure is formed according to the fluid dynamic pressure effect; the test chamber assembly drains the liquid in the plunger chamber through the pipeline, so that the liquid fills multiple liquid film pressure test assemblies;

[0009] A plurality of liquid film pressure test assemblies are connected to the test chamber assembly to respectively collect liquid film pressure signals of a plurality of set points between the plunger pairs of the high-pressure plunger pump;

[0010] The signal acquisition module extracts each liquid film pressure signal to obtain the liquid film pressure at each set point on the axial direction of the plunger.

[0011] Further, the test chamber assembly includes an outer chamber, a flange, a high-pressure plug, a transition nut, a cylindrical pin, a cooling water supply ring, a cooling ring and a cooling ring groove;

[0012] The plunger cavity and the plunger form a plunger pair; the plunger cavity is filled with liquid, a plurality of drainage holes are radially arranged on the inner wall, and an end hole is arranged on the side wall at the end;

[0013] The outer cavity is a hollow cylindrical structure, which is nested on the outer surface of the plunger cavity to radially position the plunger cavity;

[0014] The high-pressure plug is connected to the end hole of the plunger cavity, and the outside of the high-pressure plug is connected to the transition nut; the liquid flows out from the multiple drainage holes and flows into the liquid film pressure test assembly through the high-pressure plug and the transition nut;

[0015] The flange is fixed at the bottom of the plunger cavity and is provided with three interfaces, one of which is connected to the cooling water ring, which is used to test the leakage of the liquid film between the plunger and the plunger cavity; the other two interfaces are connected to the cooling ring for external cooling liquid supply to ensure the constant temperature of the liquid film between the plunger pairs;

[0016] The cylindrical pin is installed on the end face of the plunger cavity to prevent the liquid from flowing out.

[0017] Furthermore, a plurality of drainage holes are radially arranged on the inner wall of the plunger cavity, and each drainage hole is machined by electrospark machining.

[0018] Furthermore, a static seal is installed on the end face of the outer cavity to block the liquid and prevent the liquid from leaking out from the end face of the outer cavity.

[0019] Further, the liquid film pressure test assembly includes a stud, an upper support plate, a force sensor, an analog quantity acquisition card, a digital display, a high-pressure pipe, a lower support plate, a vacuum pump high-pressure pipe, a static pressure cavity, a pressure-bearing part, a transition thread, and a vacuum pump;

[0020] The studs fix the upper support plate and the lower support plate;

[0021] A transition thread hole positioning hole is provided on the upper surface of the static pressure cavity, a groove is provided on the side wall, and the inner cavity is used to contain liquid; the transition thread is embedded in the transition thread hole positioning hole;

[0022] The pressure bearing member is embedded in the groove of the static pressure cavity and communicated with the static pressure cavity, and the bottom of the pressure bearing member is fixed on the lower support plate;

[0023] One end of the high-pressure pipe is connected to the test chamber assembly, and the other end is connected to the pressure-bearing part; the other side of the pressure-bearing part is connected to the vacuum pump through the vacuum pump high-pressure pipe, and the vacuum pump is used to suck the gas in the static pressure chamber;

[0024] The force sensor is fixed at the lower end of the upper support plate, and the collection end of the force sensor fits the top of the transition thread to sense the liquid pressure of the static pressure cavity; the analog acquisition card collects the signal of the force sensor, converts it into liquid film pressure and displays it on the digital display.

[0025] Furthermore, it also includes a high-pressure pipe joint ferrule, which is arranged at the connection position between the high-pressure pipe and the pressure-bearing part to seal the liquid and ensure that the liquid does not overflow from the pressure-bearing part.

[0026] Furthermore, the dead volume of the device includes the volume of the drainage hole, the volume of the high-pressure pipe, the volume of the vacuum pump high-pressure pipe and the volume of the static pressure cavity; by reducing the channel length and the orifice diameter of the drainage hole, optimizing the layout of the high-pressure pipe and the length of the high-pressure pipe connected to the vacuum pump, the dead volume is reduced, ensuring that the liquid fills the pipeline and the static pressure cavity, and improving the accuracy of liquid film pressure measurement.

[0027] A method for performing pressure testing using a high-pressure plunger pump plunger auxiliary liquid film pressure testing device comprises:

[0028] S1: withdraw the plunger to the cooling ring to fill the plunger cavity with liquid, start the vacuum pump, and fill the high-pressure pipe, vacuum pump high-pressure pipe and static pressure cavity with liquid;

[0029] S2: The plunger and the plunger cavity move in coordination, and the liquid film pressure at the corresponding position is calculated and recorded according to the data of each digital display table;

[0030] S3: rotate the plunger counterclockwise for three times, each time by 90°, and execute step S2 after each rotation is completed; take the average value of the recorded data of each digital display table to obtain the liquid film pressure at different axial positions of the plunger.

[0031] Furthermore, in step S2, the data of the digital display is divided by the cross-sectional area of ​​the static pressure cavity to obtain the liquid film pressure at the corresponding position.

[0032] The advantages of the present invention compared with the prior art are:

[0033] (1) The high-pressure plunger pump plunger auxiliary liquid film pressure testing device designed by the present invention amplifies the liquid film volume to make it the same order of magnitude as the dead volume of the sensor, thereby overcoming the defects of the conventional pressure sensor cavity with a large dead volume and the inability to be filled with liquid. The testable liquid film pressure range is above 15MPa.

[0034] (2) The present invention adopts the method of vacuum pump suction and stop valve adjustment to efficiently extract the air in the pipeline and cavity, ensuring that there is no residual air in the static pressure cavity to interfere with the test error. In addition, the use of a high-pressure tube with an inner diameter of 0.1 mm effectively reduces the dead volume. The length of the high-pressure tube can be freely selected, and the inner diameter is, thereby improving the accuracy of the plunger pair liquid film pressure test.

[0035] (3) Compared with the development of a specific high-cost micro-volume silicon diaphragm pressure differential sensor, the processing accuracy of the liquid film pressure test assembly proposed by the present invention does not exceed 0.4μm. Compared with the purchase of a specific high-cost pressure differential sensor, the high-pressure plunger pump plunger liquid film pressure test device of the present invention has a lower cost and can be easily mass-produced to realize the function of the plunger pump test prototype. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0037] Figure 1 This is a schematic diagram of a high-pressure plunger pump liquid film pressure test principle according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of a high-pressure plunger pump liquid film pressure testing device according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of a plunger cavity assembly according to an embodiment of the present invention;

[0040] Figure 4 Schematic diagram of the plunger cavity structure of an embodiment of the present invention, (a) is a cross-sectional view, (b) is an isometric view;

[0041] Figure 5 This is a schematic diagram of a liquid membrane pressure test assembly according to an embodiment of the present invention;

[0042] Figure 6This is a schematic diagram of the principle of generating the plunger auxiliary liquid film pressure according to an embodiment of the present invention;

[0043] Figure 7 This is a structural diagram of the liquid membrane pressure test assembly cavity of an embodiment of the present invention, (a) is the pressure-bearing part, (b) is the static pressure cavity;

[0044] Figure 8 This is a diagram of the plunger liquid film pressure test steps of an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0046] The present invention proposes a high-pressure plunger pump plunger auxiliary liquid film pressure testing device, which can be applied to plunger pump friction interface testing in the aerospace field, can extract the plunger axial liquid film pressure and analyze its working film lubrication and wear state.

[0047] The device Figure 2 As shown, it includes a test chamber assembly 1, a liquid film pressure test assembly 2 and a signal acquisition module 3. The test chamber assembly 1 and the liquid film pressure test assembly 2 are connected by a high-pressure pipe. The liquid film pressure test assembly 2 uses a vacuum pump to suck liquid, fixes the pressure chamber with a force sensor, collects the liquid film pressure signal between the plunger pairs of the high-pressure plunger pump, and outputs it to the signal acquisition module 3. In this embodiment, four groups of pressure test assemblies 2 are provided for testing the pressure at four specific positions.

[0048] Test chamber component 1 Figure 3 As shown, it includes a static seal 101, an outer cavity 102, a static seal 104, a flange 105, a high-pressure plug 106, a transition nut 107, a cylindrical pin 108, an O-ring 109, a cooling water ring 110, a cooling ring 111, a cooling ring groove 112, and a secondary seal 113. The outer cavity 102 radially constrains the plunger cavity 103. Static seals 101 and 104 are installed on the end face of the outer cavity 102 to block the liquid. The secondary seal 113 has the function of weakly positioning the plunger 114 and preventing leakage. The flange 105 is provided with a test interface for testing the leakage rate and cooling interfaces 1052 and 1053 for connecting the cooling device. The three holes are designed to be independent of each other. The cooling water ring 110 and the cooling ring 111 respectively test the liquid film leakage rate between the plunger and the cavity and provide an external cooling liquid supply interface.

[0049] The plunger cavity 103 is as follows Figure 4As shown, it includes a cavity 1031, a drainage hole 1032, an end hole 1033, and a small hole 1034 on the thick end surface. The high-pressure plunger cavity 1031 is positioned with the outer cavity 102, and the inner wall of the high-pressure plunger cavity 1031 needs to have a certain thickness. In order to increase the centering, the high-pressure plug 106 and the end hole 1033 of the plunger cavity are clearance-matched to ensure that the insertion accuracy of the high-pressure pipe 208 can be flexibly adjusted. The end 1034 is pressed into the cylindrical pin 108 to prevent the liquid from flowing out of the high-pressure plunger cavity 1031 and causing leakage. Since the cavity end hole 1032 is processed by electrospark machining, the actual processing cost can be controlled.

[0050] Pressure test component 2 Figure 5 As shown, it includes studs 201, upper support plate 202, force sensor 203, nut 204, analog quantity acquisition card 205, digital display 206, O-ring 207, high-pressure pipe 208, high-pressure pipe joint ferrule 209, lower support plate 210, high-pressure pipe joint nut 211, high-pressure pipe 212, static pressure cavity 213, pressure bearing part 214, transition thread 215, vacuum pump 115, and stop valve 116. Studs 201 fix the upper support plate 202 and the lower support plate 210.

[0051] like Figure 7 As shown in (a) and (b), the pressure bearing member 214 has internal threads 2141 and 2142. The internal thread 2141 is connected to the vacuum pump high pressure pipe 212. The internal thread 2142 is connected to the high pressure pipe 208. The other end of the high pressure pipe 208 is connected to the transition nut 107. The other end of the vacuum pump high pressure pipe 212 is connected to the stop valve 116 and the vacuum pump 115. The vacuum pump 115 sucks the gas in the test assembly 2 through the stop valve 116. Figure 1 As shown, it is ensured that the residual gas is completely removed and the liquid film fills the cavity 2. The high-pressure pipe joint sleeve 209 seals the liquid and ensures that the liquid does not overflow the pressure-bearing part 214.

[0052] The static pressure cavity 213 includes a groove 2131, a transition thread hole positioning hole 2132 and an O-ring groove 2133. The transition thread 215 is embedded in the transition thread hole positioning hole 2132 to achieve assembly positioning. The pressure bearing member 214 is embedded in the groove 2131 to achieve assembly positioning. The O-ring 207 is installed in the O-ring groove 2133 to ensure that the liquid does not flow out of the cavity. The groove depth 2134 of the static pressure cavity 213 can be controlled by processing to control the dead volume of the cavity and ensure that the liquid fills the static pressure cavity groove depth 2134.

[0053] The small inner diameter section 2081 and 2121 of the high-pressure pipe are used to reduce the dead volume of the liquid film pressure test assembly 2, while ensuring the compressive strength of the pipe wall. When the liquid flows into the static pressure cavity 2134 in the high-pressure pipeline 208, the cavity 213 is subjected to the upward pressure of the liquid, which resists the transition thread 215 and transmits the force to the pressure-bearing part 214, the force sensor 203 and the upper support plate 202. The force sensor is sensitive to the force received, and the analog acquisition card 205 collects the signal value F of the force sensor 203. s1 , divided by the cross-sectional area A to convert it into pressure P, which is displayed in the digital display 206. The above setting amplifies the volume of the liquid film so that it is of the same order of magnitude as the dead volume of the sensor, thus overcoming the defects of the conventional pressure sensor cavity having a large dead volume and being unable to be filled with liquid. At the same time, the length of the high-pressure pipe 208 and the vacuum pump high-pressure pipe 212 connected from the transition nut 107 can be flexibly controlled, and the inner diameter can reach 0.1mm (a high-pressure pipe with this inner diameter can be obtained by processing or purchasing a finished product), thereby reducing the dead volume of the cavity and pipeline in the liquid film pressure test assembly 2, so as to ensure that the liquid fills the pipeline and cavity, and realizes an effective liquid film pressure test between the plunger pairs.

[0054] The principle of generating plunger auxiliary liquid film pressure is as follows Figure 6 As shown, when the plunger 114 reciprocates in the plunger cavity 103, the liquid 119 forms a narrow liquid film gap between the plunger cavity 103 and the plunger 114 due to high pressure, and forms a fluid dynamic lubrication effect. The liquid 119 flows out from the gap of the micropore 1032 and flows through Figure 4 The medium and high pressure plug 106 and the transition nut 107 flow into the static pressure cavity 213 through the high pressure pipe 208 to start testing the plunger auxiliary liquid film pressure. In addition, the length and diameter of the drainage hole 1032 can be changed to test the plunger auxiliary liquid film pressure at different axial positions.

[0055] The steps of testing using the high-pressure plunger pump plunger auxiliary liquid film pressure testing device of the present invention are as follows:

[0056] S1: Before the device is operated, the plunger is first withdrawn to the cooling ring 111 to ensure that the test chamber assembly 1 is filled with liquid, the vacuum pump is started, the high-pressure valve is opened, and the negative pressure is set to fill the high-pressure pipe 208 with liquid.

[0057] S2: Assemble the plunger 114 and the plunger cavity 103, and record the value of the tested plunger auxiliary liquid film pressure signal as in, 1 to 4 represent pressure tests using four sensors (testing the liquid film pressure at points AD of the plunger pair respectively).

[0058] S3: Rotate the plunger 90° counterclockwise and repeat step S2 for 3 times (see Figure 8 ), the liquid film pressure of each test is recorded as Take the average value to get the node pressure between the axial piston pairs to reduce the error caused by the unstable test signal:

[0059]

[0060] The effectiveness of the present invention is as follows: The feasibility of the present invention for testing liquid film pressure lies in the dead volume control of the test chamber component 1, the liquid film pressure test component 2 and the pipeline. Assume that the total dead volume is V S The dead volumes of the test chamber assembly 1, the liquid film pressure test assembly 2, the high pressure pipeline 208 and the high pressure pipeline 212 are V S1 、V S2、 V S3 、V S4 .

[0061] The dead volume of the test chamber assembly 1 all comes from the drainage hole 1032 of the plunger cavity. L1 can be within 20mm, and d1 is processed by electric spark finishing, generally 0.3mm.

[0062] The dead volume of high pressure pipeline 208 is d2 is 0.08 mm, and L2 can be less than 200 mm in length according to the installation layout. The volume of the static pressure chamber 213 is The dead volume of high pressure pipeline 212 is d2 is 0.08mm, and L3 can be no longer than 200mm depending on the installation layout.

[0063] Assume that the inner cavity of a conventional sensor is d0 and the inner cavity height is h0. The dead volume of the cavity is To verify the effectiveness, the dead volume of the present invention is compared with the original solution:

[0064]

[0065] h3 is the depth of the processing groove of the static pressure cavity 213, which can generally be 0.2mm, while the cavity height of the differential pressure sensor used in the market is h0=5mm, and the diameter d0=3mm. L2 and L3 are 200mm, L1 of the drainage hole 1032 is 20mm, and the r value is calculated to be no more than 0.5, so the present invention reduces the dead volume by at least 50%.

[0066] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-pressure plunger pump plunger auxiliary liquid film pressure test device, characterized in that: It includes a test chamber component, a liquid film pressure test component and a signal acquisition module; The test chamber assembly is connected to the plunger pair of the high-pressure plunger pump, and the liquid film pressure between the positioning plunger and the plunger chamber is formed. The plunger reciprocates, and the liquid film pressure is formed according to the fluid dynamic pressure effect; the test chamber assembly drains the liquid in the plunger chamber through the pipeline, so that the liquid fills multiple liquid film pressure test assemblies; A plurality of liquid film pressure test assemblies are connected to the test chamber assembly to respectively collect liquid film pressure signals of a plurality of set points between the plunger pairs of the high-pressure plunger pump; The signal acquisition module extracts each liquid film pressure signal to obtain the liquid film pressure at each set point on the axial direction of the plunger.

2. The high-pressure plunger pump plunger auxiliary liquid film pressure testing device according to claim 1 is characterized in that: The test chamber assembly includes an outer chamber, a flange, a high-pressure plug, a transition nut, a cylindrical pin, a cooling water supply ring, a cooling ring and a cooling ring groove; The plunger cavity and the plunger form a plunger pair; the plunger cavity is filled with liquid, a plurality of drainage holes are radially arranged on the inner wall, and an end hole is arranged on the side wall at the end; The outer cavity is a hollow cylindrical structure, which is nested on the outer surface of the plunger cavity to radially position the plunger cavity; The high-pressure plug is connected to the end hole of the plunger cavity, and the outside of the high-pressure plug is connected to the transition nut; the liquid flows out from the multiple drainage holes and flows into the liquid film pressure test assembly through the high-pressure plug and the transition nut; The flange is fixed at the bottom of the plunger cavity and is provided with three interfaces, one of which is connected to the cooling water ring, which is used to test the leakage of the liquid film between the plunger and the plunger cavity; the other two interfaces are connected to the cooling ring for external cooling liquid supply to ensure the constant temperature of the liquid film between the plunger pairs; The cylindrical pin is installed on the end face of the plunger cavity to prevent the liquid from flowing out.

3. The high-pressure plunger pump plunger auxiliary liquid film pressure testing device according to claim 2, characterized in that: A plurality of drainage holes are radially arranged on the inner wall of the plunger cavity, and each drainage hole is machined by electric spark machining.

4. The high-pressure plunger pump plunger auxiliary liquid film pressure testing device according to claim 2, characterized in that: The static seal is installed on the end face of the outer cavity to block the liquid and prevent the liquid from leaking out from the end face of the outer cavity.

5. The high-pressure plunger pump plunger auxiliary liquid film pressure testing device according to claim 1, characterized in that: The liquid film pressure test assembly includes a stud, an upper support plate, a force sensor, an analog acquisition card, a digital display, a high-pressure pipe, a lower support plate, a vacuum pump high-pressure pipe, a static pressure cavity, a pressure-bearing part, a transition thread, and a vacuum pump; The studs fix the upper support plate and the lower support plate; A transition thread hole positioning hole is provided on the upper surface of the static pressure cavity, a groove is provided on the side wall, and the inner cavity is used to contain liquid; the transition thread is embedded in the transition thread hole positioning hole; The pressure bearing member is embedded in the groove of the static pressure cavity and communicated with the static pressure cavity, and the bottom of the pressure bearing member is fixed on the lower support plate; One end of the high-pressure pipe is connected to the test chamber assembly, and the other end is connected to the pressure-bearing part; the other side of the pressure-bearing part is connected to the vacuum pump through the vacuum pump high-pressure pipe, and the vacuum pump is used to suck the gas in the static pressure chamber; The force sensor is fixed at the lower end of the upper support plate, and the collection end of the force sensor fits the top of the transition thread to sense the liquid pressure of the static pressure cavity; the analog acquisition card collects the signal of the force sensor, converts it into liquid film pressure and displays it on the digital display.

6. The high-pressure plunger pump plunger auxiliary liquid film pressure testing device according to claim 5, characterized in that: It also includes a high-pressure pipe joint ferrule, which is arranged at the connection position between the high-pressure pipe and the pressure-bearing part to seal the liquid and ensure that the liquid does not overflow from the pressure-bearing part.

7. The high-pressure plunger pump plunger auxiliary liquid film pressure testing device according to claim 5, characterized in that: The dead volume of the device includes the volume of the drainage hole, the volume of the high-pressure pipe, the volume of the vacuum pump high-pressure pipe and the volume of the static pressure cavity; by reducing the channel length and the orifice diameter of the drainage hole, optimizing the layout of the high-pressure pipe and the length of the high-pressure pipe connected to the vacuum pump, the dead volume is reduced, ensuring that the liquid fills the pipeline and the static pressure cavity, and improving the measurement accuracy of the liquid film pressure.

8. A method for performing pressure testing using the high-pressure plunger pump plunger auxiliary liquid film pressure testing device according to claim 1, characterized in that: include: S1: withdraw the plunger to the cooling ring to fill the plunger cavity with liquid, start the vacuum pump, and fill the high-pressure pipe, vacuum pump high-pressure pipe and static pressure cavity with liquid; S2: The plunger and the plunger cavity move in coordination, and the liquid film pressure at the corresponding position is calculated and recorded according to the data of each digital display table; S3: rotate the plunger counterclockwise for three times, each time by 90°, and execute step S2 after each rotation is completed; take the average value of the recorded data of each digital display table to obtain the liquid film pressure at different axial positions of the plunger.

9. The pressure test method according to claim 8, characterized in that: In step S2, the data of the digital display is divided by the cross-sectional area of ​​the static pressure cavity to obtain the liquid film pressure at the corresponding position.

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