A hydraulic variable pump circulating cooling system

Abstract

This application belongs to the field of new material testing equipment, and discloses a hydraulic variable pump circulating cooling system, which at least has an oil tank. An electric motor is arranged inside the oil tank, and the two ends of the electric motor are respectively connected to a plunger pump and a gear pump. A pilot pressure regulating overflow valve is installed on the upper cover of the oil tank. A first oil circuit is arranged between the pilot pressure regulating overflow valve and the plunger pump, and a second oil circuit is arranged between the plunger pump and the gear pump. The high-temperature oil is centrally transported to the cooler through the two oil circuits, directly controlling the heat source, avoiding the temperature rise caused by the high-temperature oil directly returning to the oil tank, significantly improving the cooling efficiency; saving materials and manufacturing costs, reducing the system cost; without adding additional valve parts or complex control mechanisms, having a simple structure, being easy to implement, being applicable to the transformation of existing hydraulic systems, and being energy-saving and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the field of new material testing equipment, and particularly to a hydraulic variable pump circulating cooling system. Background Art

[0002] Hydraulic fatigue testing machines have been widely used in the fields of material testing, fatigue testing, etc. due to their advantages such as high precision and wide range. As a silent hydraulic pumping station supporting the hydraulic fatigue testing machine, it is required to simultaneously meet the requirements of large-flow output and high-pressure small-flow working conditions. For energy-saving considerations, a constant-pressure variable plunger pump is generally used as the power source at present. However, during actual use, especially when the constant-pressure variable plunger pump works in the variable condition of high pressure and small flow for a long time, due to the operating efficiency of the variable pump and the variable control requirements, certain heat will be generated inside it. If this heat cannot be effectively cooled, it will cause the oil tank temperature to be too high, and in severe cases, it will even trigger a system alarm and shutdown, affecting the continuity and reliability of the test.

[0003] To solve this problem, the conventional solution is to additionally install a large-flow gear pump (usually 30% - 50% of the maximum flow of the variable pump) as a circulating cooling pump to provide sufficient hydraulic oil for the cooler to conduct heat exchange under variable working conditions. However, this solution has obvious drawbacks:

[0004] (1) Increase in system complexity: It is necessary to additionally configure a gear pump and its auxiliary components, which increases the system cost and maintenance difficulty;

[0005] (2) Resource waste: To ensure the cooling effect, the gear pump needs to be selected with a larger flow rate, which in turn requires the specifications of the cooler and filter to be increased accordingly, resulting in equipment redundancy and increased energy consumption;

[0006] (3) Lack of economy: The overall system volume and cost increase significantly due to the increase in the specifications of the supporting components, which is contrary to the original intention of energy saving.

[0007] Therefore, there is an urgent need for an efficient, compact and economical cooling solution to solve the heat dissipation problem of the constant-pressure variable plunger pump under high-pressure small-flow working conditions, and at the same time avoid resource waste caused by over-configuration in the prior art. Summary of the Invention

[0008] The purpose of the present invention is to provide a hydraulic variable pump circulating cooling system to overcome at least one defect of the prior art.

[0009] To achieve the above purpose, the present invention adopts the following technical solutions:

[0010] A hydraulic variable pump circulating cooling system has at least an oil tank. An electric motor is arranged inside the oil tank. Both ends of the electric motor are respectively connected to a plunger pump and a gear pump, which are used to convert electrical energy into mechanical energy to drive the plunger pump and the gear pump. A pilot pressure regulating overflow valve is installed on the upper cover of the oil tank. The pilot control oil inlet of the pilot pressure regulating overflow valve is connected to the plunger pump. The suction port of the gear pump is connected to a suction filter through a suction pipeline. A first oil circuit is also arranged between the pilot pressure regulating overflow valve and the plunger pump. The first end of the first oil circuit is arranged at the oil return port of the pilot pressure regulating overflow valve, and the second end of the first oil circuit is arranged at the standby leakage oil port of the plunger pump. A second oil circuit is arranged between the plunger pump and the gear pump. The first end of the second oil circuit is arranged at the main leakage oil port of the plunger pump, and the second end of the second oil circuit is arranged on the suction pipeline between the gear pump and the suction filter, and the second oil circuit is arranged in parallel with the suction pipeline between the second end and the suction filter.

[0011] As a preferred solution, when the external leakage oil volume of the plunger pump is greater than or equal to the delivery volume of the gear pump, the gear pump preferentially sucks hydraulic oil from the first oil circuit and the second oil circuit.

[0012] As a preferred solution, when the gear pump sucks the external leakage oil volume of the plunger pump in the first oil circuit and the second oil circuit, a boosting operation needs to be performed.

[0013] As a preferred solution, when the external leakage oil volume of the plunger pump is less than the delivery volume of the gear pump, the gear pump directly sucks oil from the oil tank through the suction port of the suction filter connected in parallel on the suction pipeline to prevent damage caused by sucking air.

[0014] As a preferred solution, the plunger pump adopts a constant pressure variable plunger pump, and the flow rate of the gear pump is 20% of the maximum flow rate of the constant pressure variable plunger pump.

[0015] As a preferred solution, couplings are arranged between the electric motor and the plunger pump and the gear pump respectively to balance the bearing capacity of the electric motor bearings and the load differences of the plunger pump and the gear pump.

[0016] As a preferred solution, a cooler is also arranged on the oil tank. A third oil circuit is connected between the cooler and the gear pump. A one-way valve is arranged on the third oil circuit to prevent reverse impact of hydraulic oil on the gear pump. When the gear pump sucks hydraulic oil during operation, it is transported to the cooler through the third oil circuit after passing through the one-way valve for heat exchange to control the temperature of the hydraulic system.

[0017] As a preferred solution, a filter is further provided on the fuel tank. The filter is arranged downstream of the cooler, and the hydraulic oil after heat exchange in the cooler is filtered by the filter and then flows back to the fuel tank.

[0018] As a preferred solution, an oil return pipe is connected to the oil return outlet of the filter, and the tail end of the oil return pipe is located below the liquid level of the hydraulic oil in the fuel tank.

[0019] As a preferred solution, a temperature monitoring device and a pressure monitoring device are further provided on the upper cover of the fuel tank to monitor the temperature and pressure of the hydraulic oil in the fuel tank in real time.

[0020] Based on the above hydraulic variable pump circulating cooling system, the following beneficial effects are achieved:

[0021] (1) In this solution, the two high-temperature oil flows of the pilot pressure regulating overflow valve oil return and the housing leakage oil of the piston pump are centrally transported to the cooler, directly controlling the heat source, avoiding the temperature rise caused by the direct return of high-temperature oil to the fuel tank, and significantly improving the cooling efficiency;

[0022] (2) Compared with the traditional solution that only cools part of the oil, this solution ensures that all the leaked oil passes through the cooler, increases the inlet oil temperature of the cooler, and improves the heat exchange efficiency;

[0023] (3) In this solution, the flow rate of the gear pump only needs to be 20% of the maximum flow rate of the piston pump, reducing the flow rate requirement of the gear pump, significantly reducing the gear pump specification. At the same time, due to the reduced flow rate, the specifications of the supporting cooler and filter can be correspondingly reduced, saving materials and manufacturing costs, and reducing the system cost;

[0024] (4) All the leaked oil (including wear particles) passes through the oil return filter, preventing pollutants from directly entering the fuel tank, improving the cleanliness and reliability of the hydraulic system, and extending the life of the oil and components.

[0025] (5) The suction filter is connected in parallel with the gear pump to automatically make up oil when the leaked oil of the piston pump is insufficient, avoiding the gear pump from sucking air and preventing damage caused by air suction;

[0026] (6) By reasonably using the spare oil port of the piston pump and existing hydraulic components (such as check valves, filters), without adding additional valve parts or complex control mechanisms, the structure is simple and easy to implement, and it is suitable for the transformation of existing hydraulic systems.

[0027] (7) It avoids the energy loss caused by the direct discharge of high-temperature oil into the fuel tank, and at the same time reduces the power consumption of the cooling system (due to the reduced flow rate of the gear pump), saving energy and being environmentally friendly. Brief Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the oil circuit structure of the hydraulic variable pump circulating cooling system according to the embodiment of the present invention;

[0029] Figure 2 It is a schematic structural diagram of the hydraulic variable pump circulating cooling system according to an embodiment of the present invention;

[0030] In the figure:

[0031] 1. Hydraulic variable pump circulating cooling system;

[0032] 10. Oil tank; 11. Upper cover; 12. Temperature monitoring device; 13. Pressure monitoring device; 14. Motor; 15. Plunger pump; 16. Gear pump; 17. Control valve; 18. Coupling; 19. Pilot pressure regulating overflow valve; 20. Suction pipeline; 200. Spare suction port; 21. Suction filter; 22. Cooler; 23. Check valve; 24. Filter; 25. Return pipe;

[0033] M1. First oil circuit; M2. Second oil circuit; A. Working pressure oil port; P. Main output port; C. Third oil circuit; X. Pilot pressure port; L. Leakage oil port; L1. Spare leakage oil port; L2. Main leakage oil port; S. Suction port. Detailed implementation manners

[0034] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that, for the convenience of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0035] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to" and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral body; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0036] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above" and "on the top" of the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the first feature has a higher horizontal height than the second feature. The first feature being "below", "below" and "under the bottom" of the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the first feature has a lower horizontal height than the second feature.

[0037] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "right", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0038] The following will specifically describe the hydraulic variable pump circulating cooling system of the present invention in conjunction with the attached Figure 1 - Figure 2 drawings.

[0039] As shown in the Figure 1 - Figure 2 drawings, a hydraulic variable pump circulating cooling system 1 of the present invention is obtained by improving and adjusting the existing hydraulic system. In the basic component part, the components of the existing hydraulic system can be adopted. For example, the fuel tank involved in this solution (partially shown in the figure) can adopt the existing fuel tank structure, which has a fuel tank 10 and an upper cover 11. The internal space formed by the fuel tank 10 and the upper cover 11 is filled with hydraulic oil. A temperature monitoring device 12 and a pressure monitoring device 13 are arranged on the upper cover 11 of the fuel tank 10 to monitor the temperature and pressure of the hydraulic oil in the fuel tank 10. Here, both the temperature monitoring device 12 and the pressure monitoring device 13 can adopt existing technologies. For example, a thermometer can be used for temperature monitoring, and a differential pressure switch can be used for pressure monitoring, etc. Since the fuel tank, the temperature monitoring device 12 and the pressure monitoring device 13 can all adopt existing technologies, no detailed description here will affect the normal understanding of the solution improvement.

[0040] A motor 14 is arranged inside the fuel tank 10. In this embodiment, the motor 14 adopts an oil-immersed silent motor, which is responsible for converting electrical energy into mechanical energy to drive the hydraulic pump. A piston pump 15 and a gear pump 16 are respectively connected to both ends of the motor 14, which are used to convert electrical energy into mechanical energy to drive the piston pump 15 and the gear pump 16. A coupling 18 is arranged between the motor 14 and the piston pump 15 and the gear pump 16 to balance the bearing capacity of the motor bearings and the load differences of the piston pump 15 and the gear pump 16. In this embodiment, the piston pump 15 adopts a constant-pressure variable piston pump, and the internal structure of the constant-pressure variable piston pump is like that of the existing piston pump structure, including a distribution plate, a cylinder sleeve piston, a slipper, a swash plate, a transmission shaft, a pilot valve, etc. A control valve 17 is connected to the high-pressure output port of the piston pump 15. In this embodiment, the control valve 17 adopts a two-position four-way control valve to control the flow path of the hydraulic oil and drive the forward and reverse rotation of the motor 14.

[0041] In this embodiment, the plunger pump 15 is provided with a working pressure oil port A connected to the high-pressure pipeline. The working pressure oil port A is connected to the main output port P through a hose; a pilot pressure port X connected to the control circuit, and the pilot pressure port X is connected to the pilot pressure regulating overflow valve 19; a suction port S connected to the fuel tank and a leakage oil port L for separate return of the oil leaked inside the pump. In this embodiment, the leakage oil port has a main leakage oil port L2 and a spare leakage oil port L1.

[0042] A pilot pressure regulating overflow valve 19 is installed at the upper cover 11 of the fuel tank. The pilot control oil inlet of the pilot pressure regulating overflow valve 19 is connected to the pilot pressure port X of the plunger pump 15. The oil return port of the pilot pressure regulating overflow valve 19 is connected to the spare leakage oil port L1 of the plunger pump 15. A hose is connected between the oil return port of the pilot pressure regulating overflow valve 19 and the spare leakage oil port L1 of the plunger pump 15 to form the first oil circuit M1 of this solution. Based on the setting of the first oil circuit M1, when the plunger pump 15 operates in a variable condition, the pilot pressure regulating overflow valve 19 will be in an open state, and the pilot high-pressure oil will flow out through the first oil circuit M1. At this time, the potential energy contained in the oil will be converted into heat energy and become a heat source. In order to prevent pressure fluctuations, it is required in control that there should be no back pressure at the oil return port. Therefore, the oil at the oil return port of the pilot pressure regulating overflow valve 19 is connected to the plunger pump 15 through the first oil circuit M1, so that the heat source oil flow is concentrated in the housing of the plunger pump 15, which is beneficial to the centralized control of the heat source.

[0043] Since there are clearance mating surfaces such as valve plates and cylinder liners in the internal structure of the plunger pump 15, as well as hydrostatic support surfaces such as slipper shoes and swash plates, a certain amount of hydraulic oil will flow out from the main leakage oil port L2 provided on the housing during normal operation. Due to the limitation of the housing structural strength of the plunger pump 15, the external leakage oil cannot withstand backpressure. The oil leaked from the high-pressure side of the plunger pump 15 contains a large amount of heat and metal particles generated by the wear of moving parts. If it is discharged into the fuel tank uncontrollably, it will not only cause temperature rise but also reduce the cleanliness of the oil, becoming a hidden danger to the reliable operation of the system. Therefore, the second oil circuit M2 is designed in this solution to adjust the above situation. One end of the second oil circuit M2 is provided at the main leakage oil port L2 of the plunger pump 15, and the other end is connected to the oil suction port of the gear pump 16. More specifically, the gear pump 16 has an oil suction port, which is connected to the hydraulic oil in the fuel tank through an oil suction pipeline 20 for the gear pump 16 to suck oil from the fuel tank. An oil suction filter 21 is provided at the port of the oil suction pipeline 20 in contact with the hydraulic oil to prevent solid particles in the oil from entering the gear pump 16. The second end of the second oil circuit M2 is connected to the oil suction pipeline 20. A spare oil suction port 200 is provided on the oil suction pipeline 20. The spare oil suction port 200 is located at the front end of the oil suction port of the oil suction filter 21. The second end of the second oil circuit M2 is connected to the spare oil suction port 200, so that the part of the oil suction pipeline 20 between the spare oil suction port 200 and the oil suction port of the oil suction filter 21 forms a parallel relationship with the second oil circuit M2 based on the connection point of the spare oil suction port 200.

[0044] Based on the settings of the above first oil circuit M1 and second oil circuit M2, the two high-temperature oil flows of the pilot pressure regulating overflow valve 19 return oil and the housing leakage oil of the plunger pump 15 are centrally processed.

[0045] It should be noted that when the external leakage oil volume of the plunger pump 15 is greater than or equal to the delivery volume of the gear pump 16, the gear pump 16 preferentially sucks the hydraulic oil from the first oil circuit M1 and the second oil circuit M2. When the gear pump 16 sucks the external leakage oil volume of the plunger pump 15 in the first oil circuit M1 and the second oil circuit M2, a pressurization operation needs to be performed. When the external leakage oil volume of the plunger pump 15 is less than the delivery volume of the gear pump 16, the gear pump 16 directly sucks oil from the fuel tank 10 through the oil suction port of the oil suction filter 21 connected in parallel to the oil suction pipeline 20 to prevent cavitation damage.

[0046] For the selection of the gear pump 16, a gear pump 16 with a smaller flow rate can be used. In this embodiment, the flow rate of the gear pump 16 being slightly greater than the heat source flow rate can achieve the normal operation of the system, usually being 20% of the maximum flow rate of the plunger pump 15. In actual use, gear pumps 16 with other flow rates can also be used.

[0047] A cooler 22 is also provided on the fuel tank 10. A third oil circuit C is connected between the cooler 22 and the gear pump 16. A check valve 23 is provided on the third oil circuit C to prevent the reverse impact of the hydraulic oil on the gear pump 16. When the gear pump 16 operates, it sucks the hydraulic oil, and after passing through the check valve 23, it is transported to the cooler 22 through the third oil circuit C for heat exchange to control the temperature of the hydraulic system.

[0048] In addition, a filter 24 is provided on the fuel tank 10. The filter 24 can use a high-precision fiberglass filter element to filter the solid particles carried in the hydraulic oil, especially the particles generated in the plunger pump 15 mentioned above. The filter 24 is provided downstream of the cooler 22. The hydraulic oil after heat exchange in the cooler 22 is filtered by the filter 24 and then flows back to the fuel tank 10; a return oil pipe 25 is connected to the oil return outlet of the filter 24, and the tail end of the return oil pipe 25 is located below the liquid level of the hydraulic oil in the fuel tank 10.

[0049] Based on the gear pump 16 that provides the circulating oil volume, the heat source oil in the first oil circuit M1 and the second oil circuit M2 is uniformly transported to the cooler 22 for heat exchange, greatly improving the heat dissipation efficiency; at the same time, the filter 24 filters the solid particles carried in the hydraulic oil, effectively ensuring the cleanliness of the hydraulic oil flowing back into the fuel tank 10.

[0050] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A hydraulic variable pump circulation cooling system, comprising at least an oil tank, characterized in that: A motor is arranged inside the oil tank, and two ends of the motor are respectively connected to a plunger pump and a gear pump for converting electrical energy into mechanical energy to drive the plunger pump and the gear pump. A pilot pressure regulating relief valve is installed on the upper cover of the oil tank, and the pilot control oil inlet of the pilot pressure regulating relief valve is connected to the plunger pump, and the oil suction port of the gear pump is connected to the oil suction filter through an oil suction pipeline; a first oil circuit is also arranged between the pilot pressure regulating relief valve and the plunger pump, and the first end of the first oil circuit is arranged at the oil return port of the pilot pressure regulating relief valve, and the second end of the first oil circuit is arranged at the spare leakage oil port of the plunger pump; a second oil circuit is arranged between the plunger pump and the gear pump, and the first end of the second oil circuit is arranged at the leakage oil port of the plunger pump, and the second end of the second oil circuit is arranged on the oil suction pipeline between the gear pump and the oil suction filter, and the second oil circuit is arranged in parallel with the oil suction pipeline between the second end and the oil suction filter; When the amount of oil leakage from the plunger pump is greater than or equal to the delivery amount of the gear pump, the gear pump preferentially draws hydraulic oil from the first oil circuit and the second oil circuit; When the amount of oil leaked from the plunger pump is less than the delivery amount of the gear pump, the gear pump directly sucks oil from the oil tank through the oil suction port of the oil suction filter connected in parallel on the oil suction pipeline to prevent cavitation damage.

2. The hydraulic variable pump circulating cooling system according to claim 1, characterized in that: When the gear pump sucks the oil leaked from the plunger pump in the first oil passage and the second oil passage, a pressurization operation needs to be performed.

3. The hydraulic variable pump circulating cooling system according to claim 1, characterized in that: The plunger pump adopts a constant pressure variable plunger pump, and the flow rate of the gear pump is 20% of the maximum flow rate of the constant pressure variable plunger pump.

4. The hydraulic variable pump circulating cooling system according to claim 1, characterized in that: A coupling is provided between the motor and the plunger pump and the gear pump to balance the bearing capacity of the motor bearing and the load difference between the plunger pump and the gear pump.

5. The hydraulic variable pump circulating cooling system according to claim 1, characterized in that: A cooler is also provided on the oil tank, and a third oil circuit is connected between the cooler and the gear pump. A one-way valve is provided on the third oil circuit to prevent the hydraulic oil from reversely impacting the gear pump. When the gear pump sucks the hydraulic oil during operation, the hydraulic oil is transported to the cooler through the third oil circuit after passing through the one-way valve for heat exchange to control the temperature of the hydraulic system.

6. The hydraulic variable pump circulating cooling system according to claim 5, characterized in that: The oil tank is also provided with a filter, which is arranged downstream of the cooler. The hydraulic oil after the heat exchange in the cooler is filtered by the filter and then flows back to the oil tank.

7. The hydraulic variable pump circulation cooling system according to claim 6, characterized in that: The oil return outlet of the filter is connected with an oil return pipe, and the tail end of the oil return pipe is located below the liquid level of the hydraulic oil in the oil tank.

8. The hydraulic variable pump circulating cooling system according to claim 1, characterized in that: The upper cover of the oil tank is also provided with a temperature monitoring device and a pressure monitoring device to monitor the temperature and pressure of the hydraulic oil in the oil tank in real time.

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