A stepless variable pressure plunger pump based on a proportional pressure reducing valve

Abstract

The application discloses a stepless variable pressure plunger pump based on a proportional pressure reducing valve, which comprises a plunger pump body, a liquid inlet and a liquid outlet are arranged on the plunger pump body, a piston is slidably arranged in a hydraulic cylinder, the piston separates the hydraulic cylinder into a sealed first cavity and a second cavity, a first port of a constant pressure valve is communicated with a hydraulic oil tank, a second port of the constant pressure valve is communicated with the second cavity, the constant pressure valve has two position states of being turned on and turned off, a cavity where a first end of a valve core of the constant pressure valve is located is communicated with the liquid outlet, a second end of the valve core of the constant pressure valve is provided with a first spring, an inlet end of a proportional pressure reducing valve is communicated with the liquid outlet of the plunger pump body, an outlet end of the proportional pressure reducing valve is communicated with a cavity where the second end of the valve core of the constant pressure valve is located, and a controller is electrically connected with the proportional pressure reducing valve. An input control signal can adjust the output pressure of the proportional pressure reducing valve, so that the control pressure of the constant pressure valve is adjusted, and the hydraulic pump works at different pressure levels. The application can be applied to a hydraulic system which needs to adjust pressure.

Description

Technical Field

[0001] This invention relates to the field of variable pressure piston pump technology, and specifically to a stepless variable pressure piston pump based on a proportional pressure reducing valve. Background Technology

[0002] Hydraulic systems are characterized by high power density and high reliability. Among them, hydraulic piston pumps, as a high-efficiency, energy-saving, and high-power power source, are widely used in hydraulic systems of aircraft, ships, and construction machinery. Industrial systems and airborne hydraulic systems both use constant-pressure variable displacement pump systems. The traditional principle of a constant-pressure variable displacement pump is as follows: the force exerted by the pump outlet pressure on the right end of the constant-pressure valve is compared with the force of the first spring on the left end to form mechanical feedback, thereby driving the follower piston to control the tilt angle of the variable swashplate.

[0003] When the hydraulic pressure at the end of the constant pressure valve core does not reach the first spring setting force, the valve core operates in the left position, the oil in the follower piston flows back to the oil tank, the tilt angle of the variable swashplate is at its maximum, and the pump's displacement is also at its maximum; when the hydraulic pressure at the right end of the valve core is greater than the first spring setting force, the valve core operates in the right position, the high-pressure oil at the pump outlet enters the follower piston chamber, driving the piston to reduce the tilt angle of the variable swashplate. When the outlet pressure and flow rate stabilize, the variable swashplate stabilizes at a certain tilt angle, at which point the constant pressure valve core is in a neutral dynamic equilibrium state.

[0004] The outlet pressure rating of a traditional constant-pressure variable pump can be set by adjusting the preload of the first spring on the left end of the constant-pressure valve. Industrial pumps and aviation pumps mostly achieve this through manual adjustment of the screw. However, traditional constant-pressure variable pumps can only operate at one or two or three pressure ratings, making them unsuitable for applications with varying pressure requirements.

[0005] However, traditional constant pressure variable pumps can usually only output a fixed pressure. Existing variable pressure pump technology is relatively complex, and the pressure fluctuations generated during pressure regulation are large, making it difficult to adapt to situations with frequent pressure changes.

[0006] How to achieve stepless and continuous adjustment of the outlet pressure of a variable pump and improve the reliability of pressure regulation under different pressure conditions is one of the important problems that urgently need to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a continuously variable pressure piston pump and hydraulic system based on a proportional pressure reducing valve, so as to overcome the shortcomings of the prior art and adapt to situations where the load pressure changes frequently.

[0008] This invention proposes a continuously variable pressure piston pump based on a proportional pressure reducing valve, comprising:

[0009] The plunger pump body includes a swashplate with a variable tilt angle; the plunger pump body is provided with an inlet and an outlet.

[0010] A hydraulic cylinder, wherein a piston is slidably mounted within the hydraulic cylinder; the piston divides the hydraulic cylinder into a sealed first chamber and a second chamber; a piston rod is connected to the side of the piston near the first chamber, and one end of the piston rod extending out of the hydraulic cylinder is connected to a swashplate with adjustable tilt angle to adjust the tilt angle of the swashplate; characterized in that: it further includes,

[0011] A constant pressure valve, wherein the first port of the constant pressure valve is connected to the hydraulic oil tank and the second port is connected to the second cavity; the constant pressure valve has two position states: on and off; the cavity where the first end of the valve core of the constant pressure valve is located is connected to the outlet, and the second end of the valve core of the constant pressure valve is provided with a first spring;

[0012] A proportional pressure reducing valve, wherein the inlet end of the proportional pressure reducing valve is connected to the outlet of the plunger pump body; and the outlet end of the proportional pressure reducing valve is connected to the cavity where the second end of the valve core of the constant pressure valve is located.

[0013] A controller is electrically connected to the proportional pressure reducing valve. The controller is used to output a control signal to the proportional pressure reducing valve to control the pressure at the output end of the proportional pressure reducing valve.

[0014] In the stepless variable pressure plunger pump based on the proportional pressure reducing valve described above, optionally, the switching between the two position states of the valve core of the constant pressure valve is controlled by the difference in thrust at both ends of the valve core.

[0015] In the continuously variable pressure plunger pump based on a proportional pressure reducing valve as described above, optionally, when the thrust received at the first end of the valve core of the constant pressure valve is greater than the thrust received at the second end, the valve core switches to the energized position; when the thrust received at the first end of the valve core of the constant pressure valve is less than the thrust received at the second end, the valve core switches to the de-energized position.

[0016] In the continuously variable pressure piston pump based on a proportional pressure reducing valve as described above, optionally, a second spring is provided in the second cavity, with one end of the second spring abutting against the piston and the other end abutting against the inner wall of the hydraulic cylinder.

[0017] The continuously variable pressure piston pump based on a proportional pressure reducing valve as described above may optionally include a branch circuit; a damper is connected in series on the branch circuit.

[0018] One end of the branch is connected to the first cavity, and the other end is connected to the second cavity.

[0019] In the continuously variable pressure piston pump based on a proportional pressure reducing valve as described above, optionally, the damper is provided with a damping orifice, which is connected in series in the branch.

[0020] In the continuously variable pressure piston pump based on a proportional pressure reducing valve as described above, optionally, the output pressure of the proportional pressure reducing valve is adjusted by a control signal to control the opening pressure of the constant pressure valve.

[0021] In the continuously variable pressure plunger pump based on a proportional pressure reducing valve as described above, optionally, the controller acquires the target load pressure and outputs a control signal to the proportional pressure reducing valve according to the target load pressure, so as to adjust the output end of the proportional pressure reducing valve to the corresponding pressure, thereby changing the thrust received by the second end of the valve core of the constant pressure valve.

[0022] In the continuously variable pressure plunger pump based on a proportional pressure reducing valve as described above, optionally, the output pressure of the plunger pump is determined by the opening pressure of the constant pressure valve.

[0023] Compared with existing technologies, this invention uses the hydraulic pressure output from the output end of a proportional pressure reducing valve to drive the movement of the valve core of a constant pressure valve. By controlling the pressure at the output end of the proportional pressure reducing valve, the movement of the valve core of the constant pressure valve is controlled. Since the pressure of the proportional pressure reducing valve can be continuously adjusted, the pressure at one end of the valve core of the constant pressure valve can be steplessly adjusted. The other end of the valve core of the constant pressure valve is connected to the outlet of the plunger pump body. When the outlet pressure is low, the first port and the second port of the constant pressure valve are connected, the oil in the second chamber is depressurized, and the hydraulic oil flows into the hydraulic oil tank through the constant pressure valve. The piston moves towards the second chamber, pushing the variable-angle swashplate in the direction of increasing outlet pressure until the outlet pressure increases to a level sufficient to push the valve core of the constant pressure valve to the open state. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0025] Explanation of reference numerals in the attached figures:

[0026] 1 - Piston pump body, 2 - Hydraulic cylinder, 3 - Constant pressure valve, 4 - Proportional pressure reducing valve, 5 - Branch circuit, 6 - Hydraulic oil tank;

[0027] 11-liquid inlet, 12-liquid outlet;

[0028] 21 - Piston, 22 - First chamber, 23 - Second chamber, 24 - Piston rod, 25 - Second spring;

[0029] 31 - Valve core, 32 - First spring;

[0030] 51 - Damper. Detailed Implementation

[0031] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0032] To address the current problems in pressure regulation of variable displacement piston pumps, and given the increasing trend of intelligent equipment development, the ability to conveniently and quickly adjust the output pressure of hydraulic pumps according to actual working conditions would bring significant flexibility and energy-saving benefits in engineering projects. Based on this, this disclosure proposes a stepless variable pressure piston pump solution using a proportional pressure reducing valve, which can achieve stepless continuous pressure regulation of the hydraulic piston pump. Exemplary embodiments of various implementation methods are described below.

[0033] Please refer to Figure 1 This invention proposes a continuously variable pressure plunger pump based on a proportional pressure reducing valve, comprising a plunger pump body 1, a hydraulic cylinder 2, a constant pressure valve 3, a proportional pressure reducing valve 4, and a controller. The plunger pump body 1 is used to pump hydraulic oil and provide pressure to the hydraulic system. The hydraulic cylinder 2 is used to drive the variable-angle swashplate of the plunger pump body 1 to move, thereby adjusting the pumping volume. The constant pressure valve 3 is used to set a corresponding pressure based on the pressure at the outlet of the proportional pressure reducing valve 4, so that the pressure at the outlet 12 of the plunger pump body 1 reaches that pressure.

[0034] Specifically, the plunger pump body 1 includes an angle-adjustable swashplate; the plunger pump body 1 is provided with an inlet 11 and an outlet 12.

[0035] The plunger pump body 1 is a swashplate-type axial plunger pump with a variable-angle swashplate for oil distribution. The pump rotates, and the variable-angle head controls the flow of the oil. Oil suction and pressure are achieved by the reciprocating motion of the plunger within the cylinder, which changes the volume of the sealed working chamber. The plunger is driven by the eccentric rotation of the pump shaft, and both its suction and discharge valves are one-way valves. When the plunger is pulled outward, the pressure in the working chamber decreases, the outlet valve closes, and when the pressure is lower than the inlet pressure, the inlet valve opens, allowing liquid to enter. When the plunger is pushed inward, the pressure in the working chamber increases, the inlet valve closes, and when the pressure is higher than the outlet pressure, the outlet valve opens, allowing liquid to exit. When the drive shaft rotates the cylinder, the variable-angle swashplate pulls the plunger out of or pushes it back into the cylinder, completing the oil suction and discharge process. The oil in the working chamber formed by the plunger and cylinder bore communicates with the pump's suction and discharge chambers through the variable-angle swashplate. Specific structural details are not elaborated further; please refer to existing technology.

[0036] A hydraulic cylinder 2 has a piston 21 slidably mounted inside it. The piston 21 divides the hydraulic cylinder 2 into a sealed first chamber 22 and a second chamber 23. A piston rod 24 is connected to the side of the piston 21 closest to the first chamber 22. One end of the piston rod 24 extends out of the hydraulic cylinder 2 and is connected to the tilt-adjustable swashplate to adjust the tilt angle of the tilt-adjustable swashplate.

[0037] Hydraulic cylinder 2 is the actuator for adjusting the tilt angle of the variable swashplate. It is used to change the tilt angle of the variable swashplate. By adjusting the tilt angle of the variable swashplate, the pump displacement and the pressure at the outlet 12 can be changed.

[0038] In this embodiment, a constant pressure valve 3 and a proportional pressure reducing valve 4 are also included. The first port of the constant pressure valve 3 is connected to the hydraulic oil tank 6, and the second port is connected to the second cavity 23. The constant pressure valve 3 has two position states: on and off. The cavity at the first end of the valve core 31 of the constant pressure valve 3 is connected to the outlet 12, and the second end of the valve core 31 of the constant pressure valve 3 is provided with a first spring 32. That is, each end of the valve core 31 of the constant pressure valve 3 has a cavity, and the two cavities are respectively connected to the outlet 12 and the outlet of the proportional pressure reducing valve 4. That is, the pressure at both ends of the valve core 31 drives the valve core 31 to move, so that the constant pressure valve 3 switches between the on and off position states.

[0039] The inlet of the proportional pressure reducing valve 4 is connected to the outlet 12 of the plunger pump body 1; the outlet of the proportional pressure reducing valve 4 is connected to the cavity where the second end of the valve core 31 of the constant pressure valve 3 is located. In specific implementation, since the outlet pressure of the proportional pressure reducing valve 4 can be adjusted in real time as needed, when the proportional pressure reducing valve 4 receives a control signal to increase the pressure, it increases the pressure at the outlet. Under the action of the pressure difference at both ends, the valve core 31 of the constant pressure valve 3 moves to the conducting position, and the piston of the hydraulic cylinder 2 moves away from the piston rod 24 to increase the pump oil volume, thereby increasing the pressure of the load system. Therefore, stepless continuous pressure adjustment can be achieved, resulting in good energy-saving effect and control performance. This scheme simplifies the variable pressure structure, reduces costs, and has strong pressure stabilization capability and strong dynamic tracking performance.

[0040] The controller is electrically connected to the proportional pressure reducing valve 4. The controller outputs a control signal to the proportional pressure reducing valve 4 to control the pressure at its output terminal. In practical implementation, the controller can adjust the output pressure of the proportional pressure reducing valve 4 to a suitable range according to the working requirements of the hydraulic load, achieving stepless adjustment within this range. This allows it to adapt to various situations with varying pressure requirements.

[0041] In practical implementation, the switching between the two position states of the valve core 31 of the constant pressure valve 3 is controlled by the difference in thrust at both ends of the valve core 31. Specifically, when the thrust at the first end of the valve core 31 is greater than the thrust at the second end, the valve core 31 switches to the open position; when the thrust at the first end is less than the thrust at the second end, the valve core 31 switches to the closed position. To ensure that the valve core 31 of the constant pressure valve 3 can adapt to a wide range of pressure regulation and to prevent the entire device from maintaining a preset pressure and thus remaining in a protected state due to the failure of the proportional pressure reducing valve 4 or the lack of a control signal, this embodiment makes the following improvement: a second spring 25 is provided inside the second cavity 23, with one end of the second spring 25 abutting against the piston 21 and the other end abutting against the inner wall of the hydraulic cylinder 2. That is, in use, the movement of the valve core 31 is achieved by the thrust difference between the two ends of the valve core 31. Specifically, the thrust at one end is provided by the pressure of the liquid outlet 12, and the thrust at the other end is provided by the outlet end of the proportional pressure reducing valve 4 and the second spring 25.

[0042] In this application, the proportional pressure reducing valve can be an electrically controlled proportional pressure reducing valve. The requirements for the proportional pressure reducing valve are limited to its function. Any electrically controlled valve that can achieve the output pressure control effect under the action of a control signal is acceptable. Those skilled in the art can select according to their needs.

[0043] In practical implementation, to provide damping for the system, stabilize the flow rate into and out of the hydraulic cylinder 2, and increase stability, this embodiment also includes a branch 5; a damper 51 is connected in series on the branch 5. One end of the branch 5 is connected to the first cavity 22, and the other end is connected to the second cavity 23. More specifically, the damper 51 is provided with a damping hole, which is connected in series on the branch 5.

[0044] In order to obtain the pressure at the outlet 12 in real time during control, and to control the proportional pressure reducing valve 4 based on the pressure at the outlet 12, a pressure sensor is included in the specific implementation. The pressure sensor is used to detect the pressure at the outlet 12. The controller is electrically connected to the pressure sensor, and the controller adjusts the control signal for controlling the proportional pressure reducing valve 4 based on the detection result of the pressure sensor. In the specific implementation, the output pressure of the proportional pressure reducing valve is adjusted by the control signal to control the opening pressure of the constant pressure valve. The output pressure of the plunger pump is determined by the opening pressure of the constant pressure valve.

[0045] In practical implementation, the plunger pump proposed in this invention can be used in a hydraulic system, such as a hydraulic system comprising the continuously variable pressure plunger pump described in this invention and a hydraulic load; the hydraulic load is connected to the outlet 12. Specifically, the controller acquires the target load pressure and outputs a control signal to the proportional pressure reducing valve 4 according to the target load pressure, so as to adjust the output end of the proportional pressure reducing valve 4 to the corresponding pressure, thereby changing the thrust received by the second end of the valve core 31 of the constant pressure valve 3. In practical implementation, the target load pressure can be determined by the controller based on the actual working conditions of the entire hydraulic system and the current pressure at the outlet 12. Since the pressure at the outlet end of the proportional pressure reducing valve 4 can be continuously and steplessly adjusted, the preset pressure on one side of the valve core 31 of the constant pressure valve 3 can be continuously adjusted, thereby increasing the pressure at one end of the outlet to the preset pressure.

[0046] In the different embodiments of the continuously variable variable piston pump described above, the components can be multiple different parts connected to each other by pipelines, or they can be integrated into a single assembly. In this case, the pipelines are not limited to actual pipes, but can also be formed by creating channels or grooves in the solid, which function as flow paths equivalent to connecting pipes.

[0047] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.

Claims

1. A continuously variable pressure piston pump based on a proportional pressure reducing valve, comprising: The plunger pump body (1) includes a variable angle swashplate; the plunger pump body (1) is provided with an inlet (11) and an outlet (12). A hydraulic cylinder (2) has a piston (21) slidably mounted inside it; the piston (21) divides the hydraulic cylinder (2) into a sealed first chamber (22) and a second chamber (23); a piston rod (24) is connected to the side of the piston (21) near the first chamber (22), and one end of the piston rod (24) extending out of the hydraulic cylinder (2) is connected to the swashplate with variable tilt angle to adjust the tilt angle of the swashplate; characterized in that: It also includes, A constant pressure valve (3) is provided. The first port of the constant pressure valve (3) is connected to the hydraulic oil tank (6), and the second port is connected to the second cavity (23). The constant pressure valve (3) has two position states: on and off. The cavity where the first end of the valve core (31) of the constant pressure valve (3) is located is connected to the liquid outlet (12). The second end of the valve core (31) of the constant pressure valve (3) is provided with a first spring (32). The proportional pressure reducing valve (4) has its inlet end connected to the outlet (12) of the plunger pump body (1); and its outlet end is connected to the cavity where the second end of the valve core (31) of the constant pressure valve (3) is located. The controller is electrically connected to the proportional pressure reducing valve (4). The controller is used to output a control signal to the proportional pressure reducing valve (4) to control the pressure at the output end of the proportional pressure reducing valve (4). It also includes a branch (5); a damper (51) is connected in series on the branch (5); One end of the branch (5) is connected to the first cavity (22), and the other end is connected to the second cavity (23); The controller acquires the target load pressure and outputs a control signal to the proportional pressure reducing valve (4) according to the target load pressure, so as to adjust the output end of the proportional pressure reducing valve (4) to the corresponding pressure, so as to change the thrust on the second end of the valve core (31) of the constant pressure valve (3).

2. The continuously variable pressure plunger pump based on a proportional pressure reducing valve according to claim 1, characterized in that: The switching of the two position states of the valve core (31) of the constant pressure valve (3) is controlled by the difference in thrust at both ends of the valve core (31).

3. The continuously variable pressure plunger pump based on a proportional pressure reducing valve according to claim 2, characterized in that: When the thrust received at the first end of the valve core (31) of the constant pressure valve (3) is greater than the thrust received at the second end, the valve core (31) switches to the open position state; when the thrust received at the first end of the valve core (31) of the constant pressure valve (3) is less than the thrust received at the second end, the valve core (31) switches to the closed position state.

4. The continuously variable pressure plunger pump based on a proportional pressure reducing valve according to claim 3, characterized in that: The second cavity (23) is provided with a second spring (25), one end of the second spring (25) abuts against the piston (21), and the other end abuts against the inner wall of the hydraulic cylinder (2).

5. The continuously variable pressure plunger pump based on a proportional pressure reducing valve according to claim 1, characterized in that: The damper (51) is provided with a damping hole, which is connected in series on the branch (5).

6. The continuously variable pressure plunger pump based on a proportional pressure reducing valve according to claim 1, characterized in that: The output pressure of the proportional pressure reducing valve is adjusted by the control signal to control the opening pressure of the constant pressure valve.

7. The continuously variable pressure plunger pump based on a proportional pressure reducing valve according to any one of claims 1-6, characterized in that: The output pressure of the plunger pump is determined by the opening pressure of the constant pressure valve.

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