A device and method for testing the consistency of compression ratio of each cylinder of a marine low-speed engine

Abstract

The present invention discloses a compression ratio consistency test device and test method for each cylinder of a marine low-speed engine, which relates to the field of engine power control. The compression ratio consistency test device for each cylinder of a marine low-speed engine comprises a cylinder assembly, which comprises a piston and a cylinder sleeve; a hydraulic actuation assembly, which corresponds to the cylinder assembly one by one, and comprises an actuation hydraulic cylinder, a pin shaft and an actuator drive unit, and the actuation hydraulic cylinder controls the top dead center and bottom dead center positions of the piston in the cylinder sleeve; a pressure assembly, which corresponds to the cylinder assembly one by one, and comprises a loading hydraulic cylinder and a loading unit, and the loading hydraulic cylinder can apply pressure to the piston. The test device provided by the present invention can reduce the test cost of marine engines, and at the same time, a test control system is used to monitor the operating status of the hydraulic system and key components in the test bench in real time, so as to realize real-time monitoring of faults of the hydraulic system and moving components, and reduce the failure rate of the compression ratio device.

Description

Technical Field

[0001] The invention relates to the technical field of engine power control, in particular to a device and method for testing the consistency of compression ratios of cylinders of a marine low-speed engine. Background Art

[0002] At present, the global trade cargo volume still mainly relies on ship transportation, mainly because of the low cost and high safety of ship transportation. However, the energy source of ship power mainly comes from fossil fuels, and the combustion of its fuel will produce a large amount of exhaust gas such as NOx, SOx, and soot particles, which seriously damages the environment. To this end, the International Maritime Organization (IMO) has formulated strict emission regulations. Effective technical means such as changing fuel injection parameters, SCR technology, EGR technology, and variable compression ratio can improve the emission performance and economic indicators of ship engines. Among them, changing the compression ratio of the engine can effectively improve the combustion characteristics of the engine. Most of the existing marine engines operate at an intermediate load condition of 50%-75% of the rated power, but the existing engines are designed with a fixed geometric compression ratio for the rated working condition of the engine. The fixed compression ratio is difficult to meet the technical requirements of the engine's variable working condition. When the compression ratio does not match the working condition, it will lead to an inappropriate air-fuel ratio during fuel combustion, resulting in incomplete fuel combustion, deteriorating the engine's power performance and emissions, and increasing the fuel consumption rate. Therefore, for the variable load condition of marine low-speed engines, it is a very meaningful work to carry out research on variable compression ratio technology on marine low-speed engines.

[0003] The structure of a low-speed marine engine is different from that of a medium- and high-speed engine. It is large in size and consumes a lot of fuel. If a variable compression ratio device is directly tested on a marine engine, the fuel cost will be high and the test cost will be extremely high. Using a small special experimental platform to test various key parameters can effectively reduce the test cost. For this reason, the development of a test bench with a variable compression ratio is a low-cost test verification method for studying the application of variable compression technology on low-speed marine engines.

[0004] Marine low-speed engines are composed of multiple cylinders working together, and each cylinder is in a relatively independent working state. When the engine is working, the combustion compression ratio of each cylinder should be consistent. To apply compression ratio technology to the engine, it is necessary to modify the compression ratio device on each cylinder. Due to the difference in the structure of the compression ratio device and the combustion of the engine cylinder, the cylinder pressure in the engine cylinder is inconsistent, causing the engine instantaneous torque to suddenly change, which destroys the stable operation of the engine. Therefore, it is also necessary to carry out cylinder compression ratio consistency test on marine low-speed engines modified with variable compression devices. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention is proposed.

[0006] To solve the above technical problems, in a first aspect, the present invention provides the following technical solutions: a compression ratio consistency test device for each cylinder of a marine low-speed engine, comprising: a cylinder assembly, at least two of which include a piston and a cylinder sleeve; a hydraulic actuating assembly, corresponding one-to-one to the cylinder assembly, comprising an actuating hydraulic cylinder, a pin shaft and an actuator drive unit, the actuating hydraulic cylinder controls the top dead center and bottom dead center positions of the piston in the cylinder sleeve, and a cavity is provided in the middle of the pin shaft; a pressure assembly, corresponding one-to-one to the cylinder assembly, comprising a loading hydraulic cylinder and a loading unit, and the loading hydraulic cylinder can apply pressure to the piston.

[0007] As a preferred solution of the compression ratio consistency testing device for each cylinder of a marine low-speed engine of the present invention, an axis center measurement component is provided at one end of the pin shaft, and the axis center measurement component is used to measure the axis center displacement value of the pin shaft.

[0008] As a preferred solution of the compression ratio consistency testing device for each cylinder of a marine low-speed engine of the present invention, the actuating hydraulic cylinder includes an actuating hydraulic cylinder sleeve, and the actuating hydraulic cylinder sleeve and the cavity together form an actuating hydraulic oil chamber.

[0009] As a preferred solution of the compression ratio consistency testing device for each cylinder of a marine low-speed engine described in the present invention, the actuating hydraulic cylinder also includes a telescopic rod, one end of the telescopic rod having a partition block is placed in the actuating hydraulic cylinder sleeve, and the partition block divides the actuating hydraulic oil chamber into an upper chamber and a lower chamber.

[0010] As a preferred solution of the compression ratio consistency testing device for each cylinder of a marine low-speed engine described in the present invention, the hydraulic actuating assembly further comprises a small end and a small end cover, the small end is arranged at the bottom of the pin shaft, the small end cover is arranged at the top of the pin shaft and fixedly connected to the small end, the small end and the small end cover wrap the pin shaft and can rotate around it, the small end is fixedly connected to the connecting rod through a connecting block, and a temperature sensor is also arranged at the bottom of the small end.

[0011] As a preferred solution of the compression ratio consistency testing device for each cylinder of a marine low-speed engine described in the present invention, the loading hydraulic cylinder has an upper chamber and a lower chamber inside, the output end of the loading hydraulic cylinder is connected to a sensor mounting seat, on which a pressure sensor is mounted, and a push rod is also installed at the bottom of the sensor mounting seat, and the other end of the push rod abuts against the top of the piston.

[0012] As a preferred solution of the compression ratio consistency testing device for each cylinder of a marine low-speed engine described in the present invention, the actuator drive unit includes an actuating pump, an actuator unit energy storage tank, an actuator unit reversing valve, an actuator unit proportional valve, an actuator unit check valve, a flow meter and an oil pressure transmitter which are sequentially connected from the oil tank to the lower chamber of the actuating hydraulic cylinder.

[0013] As a preferred solution of the compression ratio consistency testing device for each cylinder of a marine low-speed engine described in the present invention, the loading unit includes a pressure unit reversing valve, a pressure unit check valve, a pressure unit energy storage tank, a pressure unit proportional valve connected in sequence from the lower chamber line of the loading hydraulic cylinder, and the pressure unit proportional valve is also connected to the upper chamber line of the loading hydraulic cylinder.

[0014] In a second aspect, the present invention provides a method for testing the consistency of compression ratios of cylinders of a marine low-speed engine, which includes simulating the leakage of the actuator drive unit by changing the opening of an actuator unit proportional valve in the actuator drive unit, and recording the corresponding displacement values ​​of the piston under different leakage amounts; simulating the leakage of the loading unit by changing the opening of a pressure unit proportional valve in a loading unit, and recording the corresponding displacement values ​​of the piston under different leakage amounts; controlling the oil pressure of the hydraulic actuating assembly by changing the opening of the actuator unit proportional valve in the actuator drive unit, and recording the corresponding pin shaft axis change trajectory and the temperature of the temperature sensor.

[0015] As a preferred solution of the method for testing the consistency of compression ratios of cylinders of a marine low-speed engine according to the present invention, the PID controller is turned off when testing the influence of oil leakage of one of the actuator drive units or loading units on the corresponding piston; the PID controller is turned on when testing the influence of oil leakage of the actuator drive unit or loading unit on the corresponding piston and comparing it with the piston displacement values ​​of other actuator drive units or loading units in the absence of leakage.

[0016] The beneficial effects of the present invention are as follows: the test device provided by the present invention can reduce the test cost of a marine engine, and at the same time, a control test system is used to perform real-time monitoring of the operating status of a hydraulic system and key components in the test bench, thereby achieving real-time monitoring of faults in the hydraulic system and moving components, reducing the failure rate of a compression ratio device, and improving the safety of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is the overall structure diagram of the compression ratio consistency test device for each cylinder of a marine low-speed engine.

[0019] Figure 2 This is a front view of a test device for the consistency of compression ratios of cylinders of a marine low-speed engine.

[0020] Figure 3 This is a structural diagram of the components of the compression ratio consistency test device for each cylinder of a marine low-speed engine.

[0021] Figure 4 This is a structural diagram of the hydraulic actuation assembly in Example 1.

[0022] Figure 5 This is a schematic diagram of the coordination of the parts of the hydraulic actuating assembly in Example 1.

[0023] Figure 6 This is a structural diagram of the pin in Example 1.

[0024] Figure 7 It is a cross-sectional view of the cylinder assembly in Example 1.

[0025] Figure 8 This is a structural diagram of the pressure-applying component in Example 1.

[0026] Fig. 9 It is a cross-sectional view of the cylinder assembly and the hydraulic actuator assembly.

[0027] Fig.10 This is the control flow chart for cylinder compression ratio consistency test.

[0028] Fig.11 Schematic diagram of the actuator drive unit structure.

[0029] Fig.12 Schematic diagram of the loading unit structure.

[0030] In the figure: 100, cylinder assembly; 101, piston; 102, cylinder sleeve; 103, piston pin; 104, cylinder frame sleeve; 105, connecting seat; 200, hydraulic actuation assembly; 201, actuation hydraulic cylinder; 201a, actuation hydraulic cylinder sleeve; 201b, telescopic rod; 201b-1, partition block; 201c, first actuation hydraulic cylinder; 201d, second actuation hydraulic cylinder; 202, pin shaft; 202a, cavity; 202b, axis measurement assembly; 202b-1, X-direction displacement sensor; 202b-2, Y-direction displacement sensor; 202c, limit groove; 203, small end; 204, small end cover ; 205, connecting block; 206, connecting rod; 208, actuator drive unit; 208a, actuator pump; 208b, actuator unit energy storage tank; 208c, actuator unit reversing valve; 208c-1, first actuator unit reversing valve; 208c-2, second actuator unit reversing valve; 208d, actuator unit proportional valve; 208d-1, first actuator unit proportional valve; 208d-2, second actuator unit proportional valve; 208e, actuator unit one-way valve; 208e-1, first actuator unit one-way valve; 208e-2, second actuator unit one-way valve; 208e-3, third Actuator unit check valve; 208e-4, fourth actuator unit check valve; 208f, flow meter; 208f-1, first flow meter; 208f-2, second flow meter; 208f-3, third flow meter; 208f-4, fourth flow meter; 208g, oil pressure transmitter; 208g-1, first oil pressure transmitter; 208g-2, second oil pressure transmitter; 208g-3, third oil pressure transmitter; 208g-4, fourth oil pressure transmitter; 208h, actuator motor; 208i, first overflow valve; 209, bearing; 210, slider group; 211, limit block; 300, pressure group Parts; 301, loading hydraulic cylinder; 302, sensor mounting base; 303, pressure sensor; 304, push rod; 305, loading unit; 305a, pressure unit reversing valve; 305b, pressure unit one-way valve; 305c, pressure unit energy storage tank; 305d, pressure unit proportional valve; 305e, loading unit overflow valve; 306, fixing frame; 400, base assembly; 401, frame; 402, motor fixing plate; 403, table; 404, support frame; 500, transmission assembly; 501, motor; 502, sprocket assembly; 504, crankshaft; 505, crankshaft bracket; 600, oil tank. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

[0034] Example 1, reference Figure 1 to Figure 12 , which is the first embodiment of the present invention, provides a compression ratio consistency test device for each cylinder of a marine low-speed engine, and the device includes a cylinder assembly 100, a hydraulic actuating assembly 200 and a pressure applying assembly 300.

[0035] First of all, it should be noted that the cylinder assembly 100, the hydraulic actuation assembly 200 and the pressure assembly 300 are all mounted on a base assembly 400, and the base assembly 400 includes a frame 401, a motor fixing plate 402, a table 403 and a support frame 404. Figure 2 shown.

[0036] In addition, a transmission assembly 500 is installed in the base assembly 400, and the transmission assembly 500 includes a motor 501, a sprocket set 502, a crankshaft 504 and a crankshaft support 505. The motor 501 is fixedly installed on the motor fixing plate 402, and the output end of the motor 501 is provided with a sprocket set 502, and the sprocket set 502 can be used to change the torque and speed of the motor 501. The crankshaft 504 is connected to the sprocket set 502, and a plurality of crankshaft supports 505 are installed at the journal of the crankshaft 504. The crankshaft support 505 is fixed on the table 403, as shown in FIG. Figure 1 shown.

[0037] Better, refer to Figure 7 , the cylinder assembly 100 includes a piston 101 and a cylinder sleeve 102, and also includes a piston pin 103, a cylinder sleeve frame 104 and a connecting seat 105. The piston 101 is connected to the connecting seat 105 through the piston pin 103. The piston 101 can move vertically along the cylinder sleeve 102. The cylinder sleeve 102 is fixed on the cylinder sleeve frame 404, and the cylinder sleeve frame 404 is fixed on the support frame 404. The cylinder assembly 100 can be provided in multiple groups. In this embodiment, the cylinder assembly 100 is provided with two groups.

[0038] Each hydraulic actuation assembly 200 corresponds to a cylinder assembly 100, and the hydraulic actuation assembly 200 includes an actuation hydraulic cylinder 201, a pin shaft 202, a small end 203, a small end cover 204, a connecting block 205, a connecting rod 206, a temperature sensor and an actuator drive unit 208. Figure 5 shown.

[0039] The actuating hydraulic cylinder 201 includes an actuating hydraulic cylinder sleeve 201a and a telescopic rod 201b. The top of the telescopic rod 201b is fixedly connected to the connecting seat 105, and the partition block 201b-1 at the bottom is placed inside the actuating hydraulic cylinder sleeve 201a and divides the interior of the actuating hydraulic cylinder sleeve 201a into an upper chamber and a lower chamber. In this embodiment, there are two actuating hydraulic cylinders 201, namely a first actuating hydraulic cylinder 201c and a second actuating hydraulic cylinder 201d.

[0040] The middle of the pin shaft 202 is provided with a cavity 202a, and the cavity 202a and the actuating hydraulic cylinder sleeve 201a together form an actuating hydraulic oil chamber. Limiting grooves 202c are also provided on the same side of the cylindrical surface of the pin shaft 202 and on both sides of the cavity 202a. Figure 6 shown.

[0041] An axis measurement component 202 b is provided at one end of the pin shaft 202 . The axis measurement component 202 b includes an X-axis displacement sensor 202 b - 1 and a Y-axis displacement sensor 202 b - 2 , which respectively measure the radial and axial displacements of the pin shaft 202 .

[0042] The small end 203 is installed at the bottom of the pin 202, and the small end cover 204 is installed at the top of the pin 202. The two are combined up and down to wrap the pin 202 and rotate with the pin 202, and can swing around the pin 202. In addition, a bearing 209 is also provided between the small end 203 and the pin 202. A connecting block 205 is also fixedly connected to the bottom of the small end 203, and the connecting block 205 is fixedly connected to one end of the connecting rod 206, and the other end of the connecting rod 206 is connected to the crankshaft 504. It should be noted that a temperature sensor is also provided at the bottom of the small end 203.

[0043] Slider groups 210 are also provided at both ends of the pin shaft 202. Limiting blocks 211 are fixed on the slider groups 210. The limiting blocks 211 cooperate with the limiting grooves 202c on the pin shaft 202. The slider groups 210 can move vertically on the support frame 404.

[0044] The actuator drive unit 208 mainly includes an oil tank 600, an actuator hydraulic cylinder 201, an actuator pump 208a, an actuator unit energy storage tank 208b, an actuator unit reversing valve 208c, an actuator unit proportional valve 208d, an actuator unit check valve 208e, a flow meter 208f and an oil pressure transmitter 208g.

[0045] In this embodiment, the actuator unit reversing valve 208c includes a first actuator unit reversing valve 208c-1 and a second actuator unit reversing valve 208c-2;

[0046] The actuator unit proportional valve 208d includes a first actuator unit proportional valve 208d-1 and a second actuator unit proportional valve 208d-2;

[0047] The actuator unit check valve 208e includes a first actuator unit check valve 208e-1, a second actuator unit check valve 208e-2, a third actuator unit check valve 208e-3, and a fourth actuator unit check valve 208e-4;

[0048] The flow meter 208f includes a first flow meter 208f-1, a second flow meter 208f-2, a third flow meter 208f-3, and a fourth flow meter 208f-4;

[0049] The oil pressure transmitter 208g includes a first oil pressure transmitter 208g-1, a second oil pressure transmitter 208g-2, a third oil pressure transmitter 208g-3, and a fourth oil pressure transmitter 208g-4.

[0050] Specifically, Fig.11 As shown, the pipeline from the oil tank 600 to the lower chamber of the first actuating hydraulic cylinder 201c is connected in sequence with the oil filter 208f, the actuating pump 208a, the actuator unit energy storage tank 208b, the first actuator unit reversing valve 208c-1, the first actuator unit proportional valve 208d-1, the first actuator unit check valve 208e-1, the first flow meter 208f-1, and the first oil pressure transmitter 208g-1.

[0051] The pipeline from the oil tank 600 to the upper chamber of the first actuating hydraulic cylinder 201c is connected in sequence with the first actuator unit reversing valve 208c-1, the second oil pressure transmitter 208g-2, the second actuator unit check valve 208e-2, and the second flow meter 208f-2.

[0052] The pipeline from the oil tank 600 to the lower chamber of the second actuating hydraulic cylinder 201d is connected in sequence with the oil filter 208f, the actuating pump 208a, the actuator unit energy storage tank 208b, the second actuator unit reversing valve 208c-2, the second actuator unit proportional valve 208d-2, the third actuator unit one-way valve 208e-3, the third flowmeter 208f-3 and the third oil pressure transmitter 208g-3.

[0053] The pipeline from the oil tank 600 to the upper chamber of the second actuating hydraulic cylinder 201d is connected in sequence to the second actuator unit reversing valve 208c-2, the third oil pressure transmitter 208g-3, the fourth actuator unit one-way valve 208e-4 and the fourth flow meter 208f-4.

[0054] It should be noted that the actuating pump 208 a is driven by an actuating motor 208 h , and a first overflow valve 208 i is connected between the actuating pump 208 a and the oil tank 600 .

[0055] Reference Figure 8 The pressure assembly 300 includes a loading hydraulic cylinder 301 and a loading unit 305. Specifically, the loading hydraulic cylinder 301 has an upper chamber and a lower chamber. The loading hydraulic cylinder 301 is fixed on a fixing frame 306, and the fixing frame 306 is fixed to a support frame 404. A sensor mounting base 302 is installed at the output end of the loading hydraulic cylinder 301, and a pressure sensor 303 is installed on the sensor mounting base 302. The pressure sensor 303 is used to detect the pressure applied by the output end of the loading hydraulic cylinder 301. A push rod 304 is provided at the bottom of the sensor mounting base 302, and the push rod 304 abuts against the top of the piston 101. A buffer pad is also provided at the bottom of the sensor mounting base 302, and the buffer pad acts on the top of the cylinder sleeve 102.

[0056] Reference Fig.12 The loading unit 305 includes a pressure unit reversing valve 305a, a pressure unit check valve 305b, a pressure unit energy storage tank 305c, and a pressure unit proportional valve 305d, which are sequentially arranged on the lower chamber line of the loading hydraulic cylinder 301. The pressure unit energy storage tank 305c, the pressure unit check valve 305b, and the pressure unit proportional valve 305d are sequentially arranged on the upper chamber line of the loading hydraulic cylinder 301. In addition, it should be noted that a loading unit overflow valve 305e is also arranged on the upper chamber and the lower chamber lines of the loading hydraulic cylinder 301.

[0057] It is worth noting that the device also has a control module, which is mainly composed of a displacement monitoring device, a speed sensor, and a PID controller. The actuating motor 208h is provided with a displacement sensor, which transmits the difference between the collected speed signal and the reference displacement of the piston 101 to the integral controller in the PID controller, and the difference between the output value of the integral controller and the feedback signal of the hydraulic actuating component 200 is added to the proportional amplifier, and the output value of the proportional amplifier is transmitted to the servo valve, which acts on the hydraulic actuator, and the signal is then transmitted to the actuating pump 208a to collect the speed signal of the actuating motor 208h, and the signal is fed back to the integral amplifier to achieve closed-loop control of the displacement and speed signals, such as Fig.10 shown.

[0058] The working principle of the present invention is as follows: the motor 501 drives the crankshaft 504 to rotate through the sprocket set 502, and the crankshaft 504 drives the hydraulic cylinder 201 to reciprocate up and down along the support frame 404 through the connecting rod 206. At the same time, the telescopic rod 201b at the top of the hydraulic cylinder 201 drives the piston 101 to reciprocate vertically in the cylinder sleeve 102, simulating the operation of the engine cylinder.

[0059] In this process, the position of the partition block 201b-1 in the hydraulic oil chamber inside the actuating hydraulic cylinder 201 is controlled by controlling the oil pressure in the upper chamber and the lower chamber inside the actuating hydraulic cylinder 201, so that the telescopic rod 201b has different elongations, and then the position of the top dead center and the bottom dead center of the piston 101 in the cylinder sleeve 102 can be controlled to achieve simulation of different compression ratios.

[0060] In addition, by controlling the oil pressure in the upper and lower chambers of the loading hydraulic cylinder 301, the extension of the push rod 304 is controlled to apply a load to the top of the piston 101, thereby simulating the gas pressure in the engine cylinder.

[0061] In summary, the test device uses a hydraulic actuator assembly 200 to adjust the clearance height of the combustion chamber, and adjusts the clearance height to achieve adjustable compression ratio during engine combustion. Compared with other methods, using hydraulic pressure as a power source for changing the compression ratio has the advantages of large load, stable operation, and stepless adjustment of the compression ratio. The test bench is built to simulate the compression ratio consistency control output when the marine low-speed engine is modified with a compression ratio device, which overcomes the high cost of marine low-speed engine startup test and reduces the test cost.

[0062] Embodiment 2, this embodiment is based on the previous embodiment. This embodiment provides a method for testing the compression ratio consistency of each cylinder of a marine low-speed engine. The method includes:

[0063] S1: Start the electrical and hydraulic parts and check whether the moving parts are stuck.

[0064] S2: Testing the influence of the loop leakage of the actuator driving unit 208 on the testing device.

[0065] Specifically, the opening of the proportional valve 208d-1 of the first actuator unit is adjusted to a small value and the opening of the proportional valve 208d-2 of the second actuator unit is adjusted to a normal value, and the circuit of the loading unit 305 is adjusted to normal, so as to simulate the hydraulic leakage in the circuit of the first actuating hydraulic cylinder 201c in actual work;

[0066] The PID controller is turned off, and the leakage is simulated by changing the opening of the proportional valve 208d-1 of the first actuator unit. The influence of different leakages in the circuit of the first actuator hydraulic cylinder 201c on the displacement of the piston 101 in the corresponding cylinder assembly 200 is tested and recorded.

[0067] Then open the PID controller and test the displacement value of the piston 101 under the same opening of the proportional valve 208d-1 of the first actuator unit, and record the displacement value of the piston 101 in the second cylinder assembly 200; compare the displacement value of the first piston 101 with the PID controller turned off and turned on with the displacement value of the piston 101 in the second cylinder assembly 200.

[0068] S3: Test the impact of hydraulic failure of the loading unit 305 on the test bench.

[0069] Specifically, the opening of the pressure unit proportional valve 305d on the lower chamber line of the loading hydraulic cylinder 301 in the first loading unit 305 is reduced, and the opening of the pressure unit proportional valve 305d on the lower chamber line of the second loading unit 305 is adjusted to a normal value, and the actuator drive unit 208 is adjusted to normal, simulating the hydraulic leakage of the first loading unit 305 circuit in actual work;

[0070] Turn off the PID controller, and simulate the leakage in the loading unit 305 by changing the opening of the pressure unit proportional valve 305d on the lower chamber line of the loading hydraulic cylinder 301 in the first loading unit 305, and test the influence of different leakages in the loading unit 305 circuit on the displacement of the piston 101 in the corresponding first cylinder assembly 200 and record them;

[0071] Subsequently, turn on the PID control and test the displacement value of the piston 101 under the opening of the pressure unit proportional valve 305d on the lower chamber line of the loading hydraulic cylinder 301 in the same first loading unit 305, and record the displacement of the piston 101 in the second cylinder assembly 200 at the same time; compare the displacement value of the piston 101 with the PID controller turned off and with the displacement value of the piston 101 in the second cylinder assembly 200.

[0072] S4: Testing the change of the axis trajectory of the pin shaft 202 under different hydraulic pressure values.

[0073] Specifically, the opening of the first actuator unit proportional valve 208d-1 in the first actuator drive unit 208 circuit is changed to control the amount of hydraulic oil entering the first actuator drive unit 208 circuit, thereby changing the oil pressure of the first actuator hydraulic cylinder 201. The opening of the first actuator unit proportional valve 208d-1 is changed to change the oil pressure of the first actuator hydraulic cylinder 201 from 40MPa to 60Mpa, and the axis trajectory measurement component 202b is used to measure the change of the axis trajectory of the pin shaft 202 under different oil pressures, and the temperature sensor records the temperature, so as to obtain the influence of oil pressure on the axis trajectory and temperature.

[0074] It should be noted that this test method is based on the monitoring module in Example 1, and the monitoring module mainly includes a hydraulic monitoring device, a load monitoring device, a displacement monitoring device, a speed sensor, an acquisition card, and a processing controller.

[0075] The hydraulic monitoring device is the oil pressure transmitter 208g and the flow meter 208f in Example 1. The load monitoring device is the pressure sensor 303 in Example 1. The displacement sensor is composed of a displacement sensor, a bracket, and a scale. The bracket is fixed to the support frame 404, the displacement sensor is installed on the bracket, and the scale is fixed to the bottom of the piston 101.

[0076] The acquisition card is used for data collection of the hydraulic monitoring device, load monitoring device, and displacement monitoring device. The oil pressure transmitter 208g and flow meter 208f are arranged in the circuit of the actuator drive unit 208 for real-time monitoring of the pressure and flow of the hydraulic oil at the inlet and outlet of the actuator hydraulic cylinder 201, and the measured values ​​are fed back to the processing controller through the acquisition card.

[0077] The processing controller compares the measured value with the pressure and flow thresholds preset by the system to determine whether there is a pressure loss or overpressure fault in the circuit of the actuator drive unit 208.

[0078] The displacement monitoring device is used to measure the movement displacement of the piston 101, and the processing controller is used to process and analyze the values ​​collected by the acquisition card and feed them back to the user.

[0079] In summary, a closed-loop control system is used on each actuator drive unit 208, the displacement sensor performs real-time monitoring of the position of the piston 101, and the PID control method is used to perform real-time control of the operating speed of the actuator pump 208a, thereby achieving high consistency of the piston 101 when multiple actuator hydraulic cylinders 201 drive the piston 101.

[0080] The control test system is used to monitor the operating status of the hydraulic system and key components in the test bench in real time, and the monitoring values ​​are compared with the preset thresholds of the system to achieve real-time monitoring of hydraulic system and moving parts failures, reduce the failure rate of the compression ratio device, and improve the safety of the equipment.

[0081] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for testing the consistency of compression ratio of each cylinder of a marine low-speed engine, characterized in that: It includes a compression ratio consistency test device for each cylinder of a marine low-speed engine, and the compression ratio consistency test device for each cylinder of a marine low-speed engine includes: Cylinder assemblies (100), at least two of which are provided, comprising a piston (101) and a cylinder sleeve (102); A hydraulic actuating assembly (200) corresponding one-to-one to the cylinder assembly (100), comprising an actuating hydraulic cylinder (201), a pin shaft (202), and an actuator drive unit (208); the actuating hydraulic cylinder (201) controls the top dead center and bottom dead center positions of the piston (101) in the cylinder sleeve (102); a cavity (202a) is provided in the middle of the pin shaft; A pressure-applying assembly (300), corresponding one-to-one to the cylinder assembly (100), comprising a loading hydraulic cylinder (301) and a loading unit (305), wherein the loading hydraulic cylinder (301) is capable of applying pressure to the piston (101); The loading hydraulic cylinder (301) has an upper chamber and a lower chamber inside, the output end of the loading hydraulic cylinder (301) is connected to a sensor mounting seat (302) on which a pressure sensor (303) is mounted, and a push rod (304) is also mounted at the bottom of the sensor mounting seat (302), and the other end of the push rod (304) is in contact with the top of the piston (101); An axis center measurement component (202b) is provided at one end of the pin shaft (202), and the axis center measurement component (202b) is used to measure the axis center displacement value of the pin shaft (202); The actuating hydraulic cylinder (201) comprises an actuating hydraulic cylinder sleeve (201a), wherein the actuating hydraulic cylinder sleeve (201a) and the cavity (202a) together form an actuating hydraulic oil chamber; The actuating hydraulic cylinder (201) further comprises a telescopic rod (201b), one end of the telescopic rod (201b) having a partition block (201b-1) being placed in the actuating hydraulic cylinder sleeve (201a), the partition block (201b-1) dividing the actuating hydraulic oil chamber into an upper chamber and a lower chamber; The hydraulic actuation assembly (200) further comprises a small end (203) and a small end cover (204); the small end (203) is arranged at the bottom of the pin shaft (202); the small end cover (204) is arranged at the top of the pin shaft (202) and is fixedly connected to the small end (203); the small end (203) and the small end cover (204) wrap the pin shaft (202) and are capable of rotating around the pin shaft (202); the small end (203) is fixedly connected to a connecting rod (206) via a connecting block (205); and a temperature sensor is also arranged at the bottom of the small end (203); The actuator drive unit (208) comprises an actuating pump (208a), an actuator unit energy storage tank (208b), an actuator unit reversing valve (208c), an actuator unit proportional valve (208d), an actuator unit check valve (208e), a flow meter (208f) and an oil pressure transmitter (208g) which are sequentially connected from the oil tank (600) to the lower chamber of the actuating hydraulic cylinder (201); The loading unit (305) comprises a pressure unit reversing valve (305a), a pressure unit non-return valve (305b), a pressure unit energy storage tank (305c), and a pressure unit proportional valve (305d) which are sequentially connected from the lower chamber line of the loading hydraulic cylinder (301); and the pressure unit proportional valve (305d) is also connected to the upper chamber line of the loading hydraulic cylinder (301); The compression ratio consistency test method of each cylinder of the marine low-speed engine includes: Start the electrical and hydraulic parts and check whether the moving parts are stuck; Simulating the leakage of the actuator drive unit (208) by changing the opening of the actuator unit proportional valve (208d) in the actuator drive unit (208), and recording the displacement values ​​of the piston (101) corresponding to different leakage amounts; Simulating the leakage of the loading unit (305) by changing the opening size of the pressure unit proportional valve (305d) in the loading unit (305), and recording the displacement values ​​of the piston (101) corresponding to different leakage amounts; Controlling the oil pressure of the hydraulic actuation assembly (200) by changing the opening of the actuator unit proportional valve (208d) in the actuator drive unit (208), and recording the corresponding axis change trajectory of the pin shaft (202) and the temperature of the temperature sensor; The actuator unit proportional valve (208d) comprises a first actuator unit proportional valve (208d-1) and a second actuator unit proportional valve (208d-2); the opening of the first actuator unit proportional valve (208d-1) is reduced and the opening of the second actuator unit proportional valve (208d-2) is adjusted to a normal value, and the circuit of the loading unit (305) is adjusted to normal, so as to simulate hydraulic leakage in the circuit of the first actuating hydraulic cylinder (201c) in actual work; The opening of the pressure unit proportional valve (305d) on the lower chamber line of the loading hydraulic cylinder (301) in the first loading unit (305) is reduced, and the opening of the pressure unit proportional valve (305d) on the lower chamber line of the second loading unit (305) is adjusted to a normal value, and the actuator drive unit (208) is adjusted to normal, simulating a hydraulic leakage in the circuit of the first loading unit (305) in actual work; wherein the opening of the first actuator unit proportional valve (208d-1) in the first actuator drive unit (208) circuit is changed to control the amount of hydraulic oil entering the first actuator drive unit (208) circuit so as to change the oil pressure of the first actuating hydraulic cylinder (201); the opening of the first actuator unit proportional valve (208d-1) is changed so that the oil pressure of the first actuating hydraulic cylinder (201) changes from 40 MPa to 60 MPa; and the axis trajectory measurement component (202b) is used to measure the axis trajectory change of the pin shaft (202) under different oil pressures; a temperature sensor is used to record the temperature, and the influence of the oil pressure on the axis trajectory and temperature is obtained; The compression ratio consistency test device for each cylinder of a marine low-speed engine further comprises a control module, the control module comprising a displacement monitoring device, a speed sensor, and a PID controller; the actuating motor (208h) is provided with a displacement sensor, the displacement sensor transmits the difference between the collected speed signal and the reference displacement of the piston (101) to an integral controller in the PID controller, the difference between the output value of the integral controller and the feedback signal of the hydraulic actuating component (200) is added to a proportional amplifier, the output value of the proportional amplifier is transmitted to a servo valve, the servo valve acts on a hydraulic actuator, and the signal is subsequently transmitted to the actuating pump (208a) to collect the speed signal of the actuating motor (208h), and the signal is fed back to the integral amplifier to achieve closed-loop control of the displacement and speed signals.

2. The method for testing the consistency of compression ratio of each cylinder of a marine low-speed engine according to claim 1, characterized in that: When testing the effect of the oil leakage of one of the actuator drive units (208) or the loading unit (305) on the corresponding piston (101), turning off the PID controller; When testing the effect of the oil leakage of the actuator drive unit (208) or the loading unit (305) on the corresponding piston (101) and comparing it with the displacement value of the piston (101) of other actuator drive units (208) or the loading unit (305) in the absence of leakage, the PID controller is turned on.

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