A diaphragm compressor oil makeup system and method

Abstract

The application discloses a diaphragm compressor oil supplementing system, comprising: an oil supplementing oil way connected between a plunger pump and a cylinder, wherein a flow sensor one is arranged in the oil supplementing oil way; a branch oil way connected between the plunger pump and a crankcase, wherein a flow sensor two and a flow proportional valve are arranged in the branch oil way; an overflow oil way connected between the cylinder and the crankcase, wherein an overflow valve and a flow sensor three are arranged in the overflow oil way; and a PLC acquiring flow data of the flow sensor one, the flow sensor two and the flow sensor three, and capable of adjusting the opening degree of the flow proportional valve. The application further discloses a diaphragm compressor oil supplementing method. The application solves the technical problems that the oil supplementing amount cannot be dynamically adjusted, the oil supplementing amount is too much or too little, the oil supplementing system cannot be detected, and problems cannot be found in the first time.

Description

Technical Field

[0001] This invention relates to the field of diaphragm compressor technology. More specifically, this invention relates to an oil replenishment system and method for a diaphragm compressor. Background Technology

[0002] With global energy shortages becoming increasingly severe, the development of green energy has become an inevitable trend worldwide. Hydrogen, due to its abundant supply and the fact that its combustion produces only water, is hailed as the most promising clean energy source of this century. Hydrogen-powered fuel cell vehicles offer advantages such as environmental friendliness, high efficiency, zero pollution, and zero emissions. In the use and storage of hydrogen, to continuously develop and utilize hydrogen technology, it is essential to maximize the pressure of hydrogen during use. Diaphragm compressors are key equipment for hydrogen pressurization in hydrogen supply centers and refueling stations, and the cylinder head strength and diaphragm life of diaphragm compressors are particularly prominent issues in their research and development.

[0003] The hydraulic oil replenishment system of a diaphragm compressor is one of the key structures ensuring its normal operation. During operation, hydraulic oil in the compressor cylinder inevitably leaks through the piston rings, reducing the piston stroke. This means that when the piston reaches outer dead center, the diaphragm cannot properly engage with the cylinder head support plate. Leakage occurs with every revolution, so as operating time increases, the hydraulic oil in the cylinder decreases, and the clearance volume in the diaphragm cavity increases, eventually causing the compressor to stop drawing in gas and lose its working capacity. Therefore, a replenishing plunger pump must be installed in the diaphragm compressor. This replenishing plunger is typically driven by a cam on the crankshaft end, creating a phase difference with the piston movement in the crankcase, replenishing a certain amount of fluid to the hydraulic cylinder with each revolution.

[0004] In a hydraulic replenishment system, the amount and timing of hydraulic replenishment by the plunger pump are two key considerations. Generally, the timing of hydraulic replenishment for diaphragm compressors includes two main points: first, replenishment before the end of the compressor's suction stroke, i.e., before the piston reaches bottom dead center; and second, replenishment at the beginning of the compression stroke, after the piston has moved from bottom dead center. When the plunger pump's operating pressure is high, for the former, the pump begins replenishing the cylinder while the hydraulic oil pressure is still high. This effectively reduces the piston's downward stroke, potentially preventing the diaphragm from deforming sufficiently downwards, thus affecting the compressor's suction process and consequently its discharge capacity. For the latter, the replenishment time is excessively long, meaning the pump only stops replenishing when the hydraulic oil pressure in the cylinder rises to a higher level under the piston's thrust. Whether the oil replenishment time is too early or too late, for a piston pump, this means an excessive amount of oil replenishment. This is equivalent to increasing the piston's upward stroke, causing the diaphragm to contact the upper support plate of the cylinder head before the piston reaches outer dead center. If the diaphragm compressor's relief valve cannot promptly discharge the excess hydraulic oil from the cylinder, the pressure of the hydraulic oil in the cylinder will rapidly increase under the action of the piston, resulting in greater additional stress on the diaphragm and affecting the strength of the diaphragm compressor cylinder head and the diaphragm's lifespan. Therefore, designing an oil replenishment system that can improve the oil replenishment process of a high-pressure diaphragm compressor, accurately controlling the timing and amount of oil replenishment while ensuring the original structure of the diaphragm compressor remains unchanged, and ensuring the stable operation of the diaphragm compressor, is the goal pursued by designers. Summary of the Invention

[0005] One objective of this invention is to provide an oil replenishment system and method for a diaphragm compressor, which solves the technical problems of the inability to dynamically adjust the oil replenishment amount, resulting in excessive or insufficient oil replenishment, and the inability to perform status detection on the oil replenishment system, thus preventing the timely detection of problems.

[0006] To achieve these objectives and other advantages according to the present invention, a diaphragm compressor oil replenishment system is provided, comprising a diaphragm compressor cylinder, a crankcase, and a piston pump, and further comprising:

[0007] The oil replenishment circuit is connected between the plunger pump and the oil cylinder, and a flow sensor is installed in the oil replenishment circuit.

[0008] A branch oil circuit is connected between the plunger pump and the crankcase. A flow sensor and a flow proportional valve are installed in the branch oil circuit. The upper end of the branch oil circuit is connected to the replenishing oil circuit through a tee, and the connection point is located between the oil cylinder and the flow sensor.

[0009] An overflow oil circuit is connected between the oil cylinder and the crankcase. An overflow valve and a flow sensor are installed in the overflow oil circuit.

[0010] The PLC is connected to flow sensor 1, flow sensor 2 and flow sensor 3 to acquire the corresponding flow data. The PLC is also connected to the flow proportional valve and adjusts the opening degree of the flow proportional valve.

[0011] Preferably, the replenishment oil line, the tributary oil line, and the overflow oil line are distributed in parallel.

[0012] Preferably, flow sensor 1, flow sensor 2, and flow sensor 3 are all ultrasonic flow sensors.

[0013] Preferably, the PLC is also equipped with an alarm module to issue an alarm signal.

[0014] Preferably, the plunger of the plunger pump has a split structure, including a lower plunger and an upper plunger, and the space between the lower plunger and the upper plunger forms an oil chamber. The pump body of the plunger pump is provided with an oil inlet and an oil outlet that extend to the oil chamber.

[0015] This invention also provides a method for replenishing oil in a diaphragm compressor. After the diaphragm compressor is running stably, the control method is as follows:

[0016] After the diaphragm compressor is running stably, the flow ratio valve is in a completely closed state. At this time, the plunger pump replenishes oil before the end of the diaphragm compressor's suction stroke. The pressure of the hydraulic oil in the cylinder gradually decreases as the piston moves downward and gradually increases as the piston moves upward. If the pressure of the hydraulic oil in the cylinder rises to the overflow pressure set by the overflow valve, the overflow valve opens, and the hydraulic oil in the cylinder returns to the crankcase through the overflow oil passage.

[0017] Preferably, after the diaphragm compressor is running stably, flow sensor 1, flow sensor 2, and flow sensor 3 begin to monitor the hydraulic oil flow and transmit it to the PLC. The PLC acquires the flow data and compares it with the set theoretical value. The control method is as follows:

[0018] When the flow rate of flow sensor 1 decreases while the flow rate of flow sensor 2 remains unchanged, the PLC determines that the system is not replenishing oil enough and sends an alarm signal to prompt an increase in the oil replenishment pump displacement.

[0019] When the flow rate of flow sensor 1 remains constant and the flow rate of flow sensor 2 increases, the PLC determines that the system is not replenishing oil. The PLC issues a command to reduce the opening of the proportional valve to adjust the flow rate until the flow rate of flow sensor 2 returns to normal. If the flow rate of flow sensor 2 is still lower than normal when the opening of the proportional valve is 0, the PLC issues an alarm signal to prompt an increase in the displacement of the replenishing pump.

[0020] When the flow rate of flow sensor 2 remains constant, while the flow rate of flow sensor 1 increases, the PLC determines that the system is over-filled with oil. The PLC then issues a command to increase the opening of the proportional flow valve until the flow rate of flow sensor 1 returns to normal. If the flow rate of flow sensor 1 is still higher than normal when the proportional flow valve is 100% open, the PLC issues an alarm signal to prompt a reduction in the displacement of the oil replenishment pump.

[0021] Preferably, when flow sensor 1 and flow sensor 2 experience other abnormal conditions, the PLC issues an alarm signal and the system stops. Abnormal conditions include: (1) If the flow of flow sensor 1 and flow sensor 3 continues to decrease to 0 during non-shutdown process, it can be determined that the plunger pump has failed or is damaged; (2) If the flow of flow sensor 1 remains unchanged and the flow of flow sensor 2 increases, the overflow valve is damaged.

[0022] Preferably, when the PLC detects that the system's oil replenishment is insufficient, it first adjusts the flow rate through a closed-loop valve. If the set state still cannot be achieved, the PLC will alarm and prompt the user to manually adjust the plunger pump. By adjusting the size of the oil chamber, the plunger stroke is changed, thereby adjusting the displacement of the plunger pump.

[0023] The present invention has at least the following beneficial effects:

[0024] (1) The present invention performs real-time monitoring of the operating status of the oil replenishment system, which enables the compressor to operate normally and avoids major accidents;

[0025] (2) While ensuring that the original structure of the diaphragm compressor remains unchanged, the present invention can accurately grasp the timing and amount of oil replenishment of the plunger pump. The oil replenishment system can be automatically and dynamically adjusted, which can effectively reduce the power consumption of the compressor and ensure that the diaphragm compressor can operate stably.

[0026] (3) The present invention can also effectively reduce diaphragm stress and extend the life of vulnerable parts;

[0027] (4) The present invention designs a split plunger, which adjusts the stroke of the upper plunger by changing the volume of hydraulic oil in the oil chamber between the plungers, thereby achieving the purpose of adjusting the displacement of the plunger pump.

[0028] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the oil replenishment system of the present invention;

[0030] Figure 2 This is a schematic diagram of the conventional structure of the plunger pump of the present invention;

[0031] Figure 3This is a schematic diagram of the improved plunger pump of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Cylinder, 2. Exhaust valve, 3. Intake valve, 4. Oil cylinder, 5. Oil replenishment circuit, 6. Branch oil circuit, 7. Flow proportional valve, 8. Flow sensor one, 9. Flow sensor two, 10. Gear pump, 11. Plunger pump, 12. Oil suction pipe, 13. PLC, 14. Crankcase, 15. Overflow oil circuit, 16. Pulley, 17. Flow sensor three, 18. Overflow valve, 19. Plunger, 20. Pump body, 21. Lower plunger, 22. Upper plunger, 23. Oil chamber, 24. Oil inlet, 25. Oil outlet. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0035] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] like Figure 1 As shown, the present invention provides an oil replenishment system for a diaphragm compressor, including an oil cylinder 4, a crankcase 14, and a plunger pump 11 of the diaphragm compressor, and further comprising:

[0037] The oil replenishment circuit 5 is connected between the plunger pump 11 and the oil cylinder 4, and a flow sensor 8 is installed in the oil replenishment circuit 5.

[0038] Branch oil passage 6 is connected between plunger pump 11 and crankcase 14. Flow sensor 2 9 and flow proportional valve 7 are installed in branch oil passage 6. The upper end of branch oil passage 6 is connected to the oil replenishment passage 5 through a tee and the connection point is located between oil cylinder 4 and flow sensor 8.

[0039] An overflow oil passage 15 is connected between the oil cylinder 4 and the crankcase 14. An overflow valve 18 and a flow sensor 17 are installed in the overflow oil passage.

[0040] PLC13 is connected to flow sensor 8, flow sensor 9 and flow sensor 17 to acquire the corresponding flow data. PLC13 is also connected to flow proportional valve 7 to adjust the opening degree of flow proportional valve 7.

[0041] In the above technical solution, the original structure of the diaphragm compressor remains unchanged. Above the oil cylinder 4 is the air cylinder 1, and above the air cylinder 1 are the intake valve 3 and the exhaust valve 2. The replenishing plunger pump 11 is generally driven by the pulley 16 set on the crankshaft end, forming a certain phase difference with the piston movement in the crankcase 14. A certain amount of liquid is replenished to the hydraulic cylinder at each turn. The plunger pump 11 is correspondingly equipped with a gear pump 10 and an oil suction pipe 12. This application uses a PLC 13 for dynamic monitoring. The flow rate on the replenishing oil line 5, the branch oil line 6 and the overflow oil line 15 is monitored by a flow sensor to determine the replenishment amount. The replenishment amount is controlled by adjusting the flow proportional valve 7, thereby preventing the plunger pump 11 from causing a decrease in compressor discharge volume or excessive diaphragm stress due to excessive or insufficient replenishment, which would affect diaphragm life and cylinder head strength, and increase compressor power consumption.

[0042] In another technical solution, the replenishment oil line 5, the branch oil line 6, and the overflow oil line 15 are connected in parallel and distributed. Dynamic adjustment and monitoring are achieved through the three branches to control the replenishment amount.

[0043] In another technical solution, flow sensor 18, flow sensor 29, and flow sensor 317 are all ultrasonic flow sensors.

[0044] In another technical solution, the PLC13 is also equipped with an alarm module to issue an alarm signal.

[0045] In another technical solution, such as Figure 2 and Figure 3 As shown, the plunger 19 of the plunger pump 11 has a split structure, including a lower plunger 21 and an upper plunger 22. The space between the lower plunger 21 and the upper plunger 22 forms an oil chamber 23. The pump body 20 of the plunger pump 11 is provided with an oil inlet 24 and an oil outlet 25 that extend to the oil chamber 23.

[0046] In the above technical solution, the existing plunger pump 11, such as Figure 2 As shown, the following problems exist: (1) In order to standardize, various manufacturers have unified the model of the oil replenishing pump, and all models with different displacements and pressures use the same specification of oil replenishing pump. This results in the oil replenishing amount of the oil replenishing pump and the compressor not being precisely matched; (2) As the usage time increases, the sealing ability weakens and the hydraulic oil leakage increases, but the oil replenishing amount of the oil replenishing pump cannot be adjusted during operation. Therefore, this application uses a plunger pump 11 with adjustment function, such as Figure 3As shown, the plunger 19 of the plunger pump 11 is configured as a separate unit. When the PLC 13 detects insufficient oil replenishment in the system, it first adjusts the flow through the proportional flow valve 7 in a closed loop. If the ideal state is still not achieved, the PLC 13 will alarm and prompt manual adjustment of the plunger pump 11. Generally, two situations will increase the flow rate of the plunger pump 11: a weakened piston sealing capability and a reduced efficiency of the plunger pump 11. A weakened piston sealing capability will increase the hydraulic oil leakage of the piston in each stroke (the value of flow sensor 3 17 decreases). A reduced efficiency of the plunger pump 11 will increase the hydraulic oil leakage of the plunger. At this time, the oil replenishment is reduced (the value of flow sensor 2 9 decreases), and the flow rate of the plunger pump 11 needs to be increased. The specific increase can only be adjusted slowly. At this time, the value of the overflow sensor will increase. When it is increased to the normal level, it is sufficient.

[0047] The split-type plunger of this application adjusts the stroke of the upper plunger 22 by changing the volume of hydraulic oil in the oil chamber 23 between the lower plunger 21 and the upper plunger 22, thereby adjusting the displacement of the plunger pump 11. When the oil chamber 23 is full of oil, the plunger stroke is the same as the existing modified scheme. When the plunger oil chamber 23 is empty, the plunger stroke is about 5% of the original scheme. By changing the amount of oil filling, the plunger stroke is changed, thereby adjusting the displacement.

[0048] This invention also provides a method for replenishing oil in a diaphragm compressor. After the diaphragm compressor is running stably, the control method is as follows:

[0049] After the diaphragm compressor is running stably, the flow ratio valve 7 is in a completely closed state. At this time, the plunger pump 11 replenishes oil before the end of the diaphragm compressor's suction stroke. The pressure of the hydraulic oil in the cylinder 4 gradually decreases as the piston moves downward and gradually increases as the piston moves upward. If the pressure of the hydraulic oil in the cylinder 4 rises to the overflow pressure set by the overflow valve 18, the overflow valve 18 opens, and the hydraulic oil in the cylinder 4 returns to the crankcase 14 through the overflow oil passage 15.

[0050] After the diaphragm compressor is running stably, flow sensors 8, 9, and 17 begin to monitor the hydraulic oil flow and transmit the data to PLC13. PLC13 acquires the flow data and compares it with the set theoretical value. The control method is as follows:

[0051] When the flow rate of flow sensor 8 decreases while the flow rate of flow sensor 9 remains unchanged, PLC13 determines that the system is not replenishing oil enough and sends an alarm signal to prompt an increase in the oil replenishment pump displacement.

[0052] When the flow rate of flow sensor 8 remains unchanged, while the flow rate of flow sensor 9 increases, PLC13 determines that the system is not replenishing oil. PLC13 issues a command to reduce the opening of the proportional flow control valve 7 until the flow rate of flow sensor 9 returns to normal. If the flow rate of flow sensor 9 is still below the normal level when the opening of proportional flow control valve 7 is 0, PLC13 issues an alarm signal to prompt an increase in the displacement of the replenishing pump.

[0053] When the flow rate of flow sensor 29 remains unchanged, the flow rate of flow sensor 8 increases. At this time, PLC13 determines that the system is replenishing too much oil. PLC13 issues a command to increase the opening of the flow proportional valve 7 until the flow rate of flow sensor 8 returns to normal. If the flow rate of flow sensor 8 is still higher than normal when the opening of the flow proportional valve 7 is 100%, PLC13 issues an alarm signal to prompt a reduction in the displacement of the replenishing pump.

[0054] When flow sensor 8 and flow sensor 9 experience other abnormalities, PLC13 will issue an alarm signal and the system will stop. Abnormalities include: (1) If the flow of flow sensor 8 and flow sensor 3 17 continues to decrease to 0 during non-stop operation, it can be determined that the plunger pump 11 has failed or is damaged; (2) If the flow of flow sensor 8 remains unchanged and the flow of flow sensor 2 9 increases, the overflow valve 18 is damaged.

[0055] When PLC13 detects that the system's oil replenishment is insufficient, it first adjusts the flow proportional valve 7 in a closed loop. If the set state still cannot be achieved, PLC13 will alarm and prompt manual adjustment of the plunger pump 11. The plunger stroke is changed by adjusting the size of the oil chamber 23, thereby adjusting the displacement of the plunger pump 11.

[0056] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for replenishing oil in a diaphragm compressor, characterized in that, The oil replenishment method is based on an oil replenishment system, which includes the diaphragm compressor's oil cylinder, crankcase, and plunger pump, and also includes: The oil replenishment circuit is connected between the plunger pump and the oil cylinder, and a flow sensor is installed in the oil replenishment circuit. A branch oil circuit is connected between the plunger pump and the crankcase. A flow sensor and a flow proportional valve are installed in the branch oil circuit. The upper end of the branch oil circuit is connected to the replenishing oil circuit through a tee, and the connection point is located between the oil cylinder and the flow sensor. An overflow oil circuit is connected between the oil cylinder and the crankcase. An overflow valve and a flow sensor are installed in the overflow oil circuit. The PLC is connected to flow sensor 1, flow sensor 2 and flow sensor 3 to acquire the corresponding flow data. The PLC is also connected to the flow proportional valve and adjusts the opening degree of the flow proportional valve. The PLC is also equipped with an alarm module to issue an alarm signal; the plunger of the plunger pump has a split structure, including a lower plunger and an upper plunger, and the space between the lower plunger and the upper plunger forms an oil chamber. The pump body of the plunger pump is provided with an oil inlet and an oil outlet that extend to the oil chamber. After the diaphragm compressor is running stably, the control method is as follows: After the diaphragm compressor is running stably, the flow ratio valve is in a completely closed state. At this time, the plunger pump replenishes oil before the end of the diaphragm compressor's suction stroke. The pressure of the hydraulic oil in the cylinder gradually decreases as the piston moves downward and gradually increases as the piston moves upward. If the pressure of the hydraulic oil in the cylinder rises to the overflow pressure set by the overflow valve, the overflow valve opens and the hydraulic oil in the cylinder returns to the crankcase through the overflow oil passage. After the diaphragm compressor is running stably, flow sensors 1, 2, and 3 begin monitoring the hydraulic oil flow and transmitting the data to the PLC. The PLC acquires the flow data and compares it with the set theoretical value. The control method is as follows: When the flow rate of flow sensor 1 decreases while the flow rate of flow sensor 2 remains unchanged, the PLC determines that the system is not replenishing oil enough and sends an alarm signal to prompt an increase in the oil replenishment pump displacement. When the flow rate of flow sensor 1 remains constant and the flow rate of flow sensor 2 increases, the PLC determines that the system is not replenishing oil. The PLC issues a command to reduce the opening of the proportional valve to adjust the flow rate until the flow rate of flow sensor 2 returns to normal. If the flow rate of flow sensor 2 is still lower than normal when the opening of the proportional valve is 0, the PLC issues an alarm signal to prompt an increase in the displacement of the replenishing pump. When the flow rate of flow sensor 2 remains constant, while the flow rate of flow sensor 1 increases, the PLC determines that the system is over-filled with oil. The PLC issues a command to increase the opening of the flow proportional valve until the flow rate of flow sensor 1 returns to normal. If the flow rate of flow sensor 1 is still higher than normal when the opening of the flow proportional valve is 100%, the PLC issues an alarm signal to prompt the reduction of the oil replenishment pump displacement. When the PLC detects that the system's oil replenishment is insufficient, it first adjusts the flow rate through a closed-loop valve. If the set state still cannot be achieved, the PLC will alarm and prompt the user to manually adjust the plunger pump. By adjusting the size of the oil chamber, the plunger stroke is changed, thereby adjusting the displacement of the plunger pump. When flow sensor 1 and flow sensor 2 experience other abnormalities, the PLC will issue an alarm signal and the system will stop. Abnormalities include: (1) If the flow of flow sensor 1 and flow sensor 3 continues to decrease to 0 during non-stop operation, it can be determined that the plunger pump has failed or is damaged; (2) If the flow of flow sensor 1 remains unchanged and the flow of flow sensor 2 increases, the overflow valve is damaged.

2. The method for replenishing oil in a diaphragm compressor as described in claim 1, characterized in that, The replenishment oil line, the tributary oil line, and the overflow oil line are distributed in parallel.

3. The method for replenishing oil in a diaphragm compressor as described in claim 1, characterized in that, Flow sensor 1, flow sensor 2 and flow sensor 3 are all ultrasonic flow sensors.

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