Variable displacement device, control method and plunger pump

Abstract

According to the variable device, the control method and the plunger pump, an electric driving device drives a variable piston to move to adjust the angle of a swash plate, a hydraulic valve and a return spring in an existing device are abandoned, the control stability is better, the response time is short, the overall structure is simple, and the cost is low.

Description

Technical Field

[0001] The invention relates to a variable device, a control method and a plunger pump, and belongs to the field of hydraulic pumps. Background Art

[0002] With the development trend of miniaturization and simplified structure of plunger pumps, smaller plunger pump products have appeared in recent years, especially miniaturized designs for variable displacement devices. Figure 1 , based on the traditional plunger pump constant power control method, this structure redesigns the variable device, and controls the hydraulic oil to flow into or out of the variable piston 1 through the control valve to change the swash plate and the pump displacement. In this variable device, one side of the swash plate contacts the variable piston 1, and the other side contacts the return spring 2. The return stroke of the swash plate, that is, the process of the swash plate changing from 0 displacement to large displacement, mainly depends on the spring force. This structure has the following limitations: 1) Due to the use of hydraulic valve control, valve stagnation is prone to occur, and the control stability is poor; 2) The structure is complex, the processing is difficult, and the cost is high; 3) Since the swash plate is the return stroke of the return spring 2, the variable response time is long; 4) The spring force is small and the area of ​​the variable piston 1 is large, so the pressure after the valve is low, and the control structure is easily affected by the outlet pressure and the return oil pressure, so the control stability is poor. Summary of the invention

[0003] The present invention provides a variable device, a control method and a plunger pump, which solve the problems disclosed in the background technology.

[0004] According to one aspect of the present disclosure, a variable device is provided, including a variable piston arranged in a piston hole of a pump housing, wherein one end of the variable piston facing the inner cavity of the pump housing is rotatably connected to a swash plate, and the other end of the variable piston facing outside the pump housing is connected to an electric drive device.

[0005] In some embodiments of the present disclosure, an oil pool is formed between the variable piston and the piston hole, and the oil pool is connected to the oil supply port and the oil return chamber. When the variable piston moves toward the inner cavity of the pump housing, the volume of the oil pool increases, and when the variable piston moves outside the pump housing, the volume of the oil pool decreases.

[0006] In some embodiments of the present disclosure, the oil pool is connected to an external oil supply port through an electronic control device; wherein the electronic control device controls the pressure of the fluid between the oil pool and the oil supply port.

[0007] In some embodiments of the present disclosure, the electric drive device is a lead screw driven by a motor, and the moving block of the lead screw is connected to the variable piston.

[0008] In some embodiments of the present disclosure, the electric drive device includes a motor, an output end of the motor is connected to a screw rod, and a screw hole is provided at one end of the variable piston facing outside the pump housing, and the screw rod is screwed into the screw hole.

[0009] According to another aspect of the present disclosure, a control method of a variable device is provided, wherein the variable device is the variable device described above, and the control method comprises: In response to the need to reduce the swash plate angle, controlling the electric drive device to drive the variable piston to move toward the outside of the pump housing; In response to the need to increase the swash plate angle, the electric drive device is controlled to drive the variable piston to move toward the inner cavity of the pump housing.

[0010] In some embodiments of the present disclosure, if the variable device includes an oil pool and the oil pool is externally connected to the oil supply port through the electronic control device; If the variable device includes an oil pool and the oil pool is externally connected to the oil supply port and the oil return chamber through the electronic control device; In response to the need to increase the angle of the swash plate, the electric control device between the oil pool and the oil supply port is controlled to open, the electric control device between the oil pool and the oil return chamber is closed, and the electric drive device is controlled to drive the variable piston to move toward the inner cavity of the pump housing; In response to the need to reduce the swash plate angle, the electric control device between the oil pool and the oil supply port is controlled to be closed, the electric control device between the oil pool and the oil return chamber is opened, and the electric drive device is controlled to drive the variable piston to move outside the pump housing.

[0011] According to another aspect of the present disclosure, a plunger pump is provided, characterized in that it includes the above-mentioned variable device.

[0012] In some embodiments of the present disclosure, if the variable device includes an oil pool, and the plunger pump rotates in only one direction, the oil discharge port of the valve plate of the plunger pump is connected to the oil pool.

[0013] In some embodiments of the present disclosure, if the variable device includes an oil pool and the plunger pump rotates bidirectionally, the oil ports of the valve plate of the plunger pump are connected to the oil pool through a shuttle valve.

[0014] The beneficial effects achieved by the present invention are as follows: the present invention drives the variable piston movement to adjust the angle of the swash plate through an electric drive device, thereby eliminating the hydraulic valve and return spring in the existing device, achieving better control stability and shorter response time, and having a simple overall structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of an existing plunger pump; Figure 2 is a schematic diagram of a variable device of the present invention; Figure 3 It is a schematic diagram of the first structure of the plunger pump of the present invention; Figure 4 It is a second structural schematic diagram of the plunger pump of the present invention; Figure 5 This is a third structural schematic diagram of the plunger pump of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. It is obvious that the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0017] Unless otherwise specified, the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0018] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0019] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0020] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0021] It should be noted that similar symbols and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

[0022] In order to solve the problems existing in the variable device of the existing plunger pump, the present disclosure proposes a variable device, a control method and a plunger pump.

[0023] Figure 2 This is a schematic diagram of an embodiment of the variable device disclosed in the present invention, which may specifically include a variable piston 1 embedded in the piston hole 4 of the pump housing 9, the variable piston 1 is rotatably connected to the swash plate 3 at one end facing the inner cavity of the pump housing 9, and the variable piston 1 is connected to an electric drive device at one end facing the outside of the pump housing 9.

[0024] It should be noted that the piston hole 4 is tilted at an angle of about 30 degrees and can be divided into two coaxial sections, with the aperture of the section close to the swash plate 3 being larger than the aperture of the other end. The variable piston 1 is adapted to the piston hole 4 and can also be divided into two sections, one thick and one thin, and the thick section can only move in the large hole.

[0025] It should be noted that, in order to ensure smooth rotation of the swash plate 3 , a positioning pin may be used to realize the rotational connection between the variable piston 1 and the swash plate 3 .

[0026] It should be noted that the structure of the electric drive device can be of many kinds, such as an electric cylinder, the telescopic end of which is directly connected to the variable piston 1. However, in order to make the control more stable, in some embodiments, the electric drive device can use a lead screw driven by the motor 6, and a mounting seat can be fixed at the end of the piston hole 4 facing outward, and the lead screw and the motor 6 can be installed on the mounting seat, and the moving block of the lead screw is directly connected to the variable piston 1, and the motor 6 drives the lead screw to drive the variable piston 1 to move along the piston hole 4.

[0027] In some embodiments, the electric drive device can also use a screw 7 driven by a motor 6, which can specifically include a motor 6 and a screw 7. Similar to a lead screw, a mounting seat can be fixed at the outward end of the piston hole 4, and the motor 6 can be installed on the mounting seat. The output end of the motor 6 is connected to the screw 7. A screw hole 8 is opened at the end of the variable piston 1 facing the outside of the pump housing 9, or a nut is installed on the positioning pin, and the screw 7 is screwed into the screw hole 8. The motor 6 drives the screw 7 to rotate, and the screw hole 8 drives the variable piston 1 to move along the piston hole 4.

[0028] It should be noted that in order to miniaturize the device, it is necessary to use an electric drive device (i.e., motor 6) that is as small as possible, and a small motor 6 can only output a small thrust. Therefore, in order to enhance the thrust on the swash plate 3, an auxiliary device is also provided in some embodiments, specifically, an oil pool 5 between the variable piston 1 and the piston hole 4.

[0029] Figure 2 In the embodiment, as the piston moves, the thin section of the piston will enter the large hole. At this time, a space, namely, the oil pool 5, will be formed between the inner wall of the large hole, the thin section of the piston and the thick section of the piston. When the variable piston 1 moves toward the inner cavity of the pump housing 9, the volume of the oil pool 5 will increase. When the variable piston 1 moves toward the outside of the pump housing 9, the volume of the oil pool 5 will decrease. The oil pool 5 is externally connected to the oil supply port and the oil return cavity in the pump housing 9 (not shown in the figure). By inputting pressure oil into the oil pool 5, the variable piston 1 is assisted to move toward the inner cavity of the pump housing 9. Conversely, by outputting pressure oil into the oil pool 5, the variable piston 1 is assisted to move toward the outside of the pump housing 9. The oil pool 5, combined with the pressure oil, can assist the electric drive device in completing the variable action, which reduces the thrust of the electric drive device and helps to reduce the size of the electric drive device.

[0030] It should be noted that, in order to make the control more stable, in some embodiments, an electronic control device will be installed between the oil pool 5 and the oil supply port, and between the oil pool 5 and the oil return chamber. The electronic control device between the oil pool 5 and the oil supply port is used to control the pressure of the fluid between the oil pool 5 and the oil supply port. Specifically, an electromagnetic proportional valve 17 can be used. The electronic control device between the oil pool 5 and the oil return chamber is mainly used to control the on-off of the oil circuit, and a simple electronic control valve can be used.

[0031] It should be noted that since the above-mentioned drives are all electronically controlled, they can be uniformly controlled by a controller. The specific control method can be as follows: When only the electric drive device is used to drive the variable piston 1: In response to the need to reduce the angle of the swash plate 3, the electric drive device is controlled to drive the variable piston 1 to move toward the outside of the pump housing 9; in response to the need to increase the angle of the swash plate 3, the electric drive device is controlled to drive the variable piston 1 to move toward the inner cavity of the pump housing 9.

[0032] When the electric drive device and the electric control device are used to drive the variable piston 1: In response to the need to increase the angle of the swash plate 3, the electronic control device between the oil pool 5 and the oil supply port is controlled to open, the electronic control device between the oil pool 5 and the oil return chamber is closed, and the electric drive device is controlled to drive the variable piston 1 to move toward the inner cavity of the pump housing 9; in response to the need to decrease the angle of the swash plate 3, the electronic control device between the oil pool 5 and the oil supply port is controlled to close, the electronic control device between the oil pool 5 and the oil return chamber is opened, and the electric drive device is controlled to drive the variable piston 1 to move outside the pump housing 9.

[0033] Taking the use of the same controller to control the motor 6 and the electromagnetic proportional valve 17 as an example, the motor 6 receives the proportional signal. After the pressure of the electromagnetic proportional valve 17 is adjusted, when the pump variable is working, it receives the on-off signal sent by the controller. The two signals are controlled in coordination to complete the variable action: When a positive signal is output to the motor 6, causing the swash plate to rotate to a large angle, at the same time, the electromagnetic proportional valve 17 is connected to the signal, opening the oil path from the pump oil discharge port to the oil pool 5, and at the same time, cutting off the oil path from the oil pool 5 to the oil return chamber of the housing, so as to assist the variable piston in pushing the swash plate to rotate to a large angle. When a negative signal is output to the motor 6, causing the swash plate to rotate to a small angle, at the same time, the electromagnetic proportional valve 17 is disconnected from the signal, cutting off the oil path from the pump oil discharge port to the oil pool 5, and at the same time, opening the oil path from the oil pool 5 to the oil return chamber of the housing, so that the variable piston pulls the swash plate to rotate to a small angle.

[0034] The above device drives the variable piston 1 to move and adjust the angle of the swash plate 3 through an electric drive device, eliminating the hydraulic valve and return spring in the existing device. At the same time, the auxiliary device is also electrically controlled, which has better control stability and short response time, and the overall structure is simple and low cost.

[0035] Figure 3 It is a schematic diagram of an embodiment of the plunger pump disclosed in the present invention, which specifically includes the above-mentioned variable device.

[0036] It should be noted that other structures of the plunger pump are some common structures, including a rear cover 10 fixed to the pump housing 9, a distribution plate 14 is installed on the side of the rear cover 10 facing the inner cavity, and there are relative arc-shaped oil ports on the distribution plate 14, which are defined as a first arc-shaped oil port 13 and a second arc-shaped oil port 15.

[0037] See Figure 4 If the plunger pump rotates in only one direction, the first arc-shaped oil port 13 is the oil discharge port, the second arc-shaped oil port 15 is the oil suction port, and the first arc-shaped oil port 13 is connected to the oil pool 5 through the electromagnetic proportional valve 17.

[0038] See Figure 5 If the plunger pump rotates in both directions, the oil ports of the distribution plate 14 are connected to the oil pool 5 through the shuttle valve 18, that is, the first arc-shaped oil port 13 and the second arc-shaped oil port 15 can be connected using the shuttle valve 18. No matter which oil port is high pressure, the high-pressure side pressure oil will be introduced into the electromagnetic proportional valve 17 through the shuttle valve 18 and finally reach the oil pool 5.

[0039] The electromagnetic proportional valve 17 can reduce the pump outlet pressure to a set pressure. In a specific implementation, the output pressure of the electromagnetic proportional valve 17 can be positively correlated with the input signal or negatively correlated with the input signal.

[0040] It should be noted that the pump housing 9 includes an outer wall (i.e. Figure 3 16), the piston hole 4 is opened in the outer wall. The swash plate 3 is supported by a semicircular track 11 processed in the pump housing 9, and the end of the swash plate 3 away from the variable piston 1 is rotatably connected by a plunger 12, so that the swash plate 3 can move around the semicircular track 11.

[0041] The above plunger pump drives the variable piston 1 to move and adjust the angle of the swash plate 3 through an electric drive device, eliminating the hydraulic valve and return spring in the existing device. At the same time, the auxiliary device is also electrically controlled, which has better control stability and short response time, and the overall structure is simple and low cost.

[0042] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A variable device, characterized in that: The invention comprises a variable piston arranged in a piston hole of a pump housing, wherein one end of the variable piston facing the inner cavity of the pump housing is rotatably connected to a slant plate, and one end of the variable piston facing the outside of the pump housing is connected to an electric drive device.

2. The variable device according to claim 1, characterized in that: An oil pool is formed between the variable piston and the piston hole, and the oil pool is externally connected to the oil supply port and the oil return chamber. When the variable piston moves toward the inner cavity of the pump housing, the volume of the oil pool increases, and when the variable piston moves toward the outside of the pump housing, the volume of the oil pool decreases.

3. The variable device according to claim 2, characterized in that: The oil pool is connected to an external oil supply port through an electronic control device, wherein the electronic control device controls the pressure of the fluid between the oil pool and the oil supply port.

4. The variable device according to claim 1, characterized in that: The electric drive device is a lead screw driven by a motor, and the moving block of the lead screw is connected to the variable piston.

5. The variable device according to claim 1, characterized in that: The electric drive device comprises a motor, the output end of the motor is connected to a screw rod, and a screw hole is arranged at one end of the variable piston facing the outside of the pump housing, and the screw rod is screwed into the screw hole.

6. A control method for a variable device, characterized in that: The variable device is the variable device according to any one of claims 1 to 5, and the control method comprises: In response to the need to reduce the swash plate angle, controlling the electric drive device to drive the variable piston to move toward the outside of the pump housing; In response to the need to increase the swash plate angle, the electric drive device is controlled to drive the variable piston to move toward the inner cavity of the pump housing.

7. The control method of the variable device according to claim 6, characterized in that: If the variable device includes an oil pool and the oil pool is externally connected to the oil supply port and the oil return chamber through the electronic control device; In response to the need to increase the angle of the swash plate, the electric control device between the oil pool and the oil supply port is controlled to open, the electric control device between the oil pool and the oil return chamber is closed, and the electric drive device is controlled to drive the variable piston to move toward the inner cavity of the pump housing; In response to the need to reduce the swash plate angle, the electric control device between the oil pool and the oil supply port is controlled to be closed, the electric control device between the oil pool and the oil return chamber is opened, and the electric drive device is controlled to drive the variable piston to move outside the pump housing.

8. A plunger pump, characterized in that: Includes the variable device as described in any one of claims 1 to 5.

9. The plunger pump according to claim 8, characterized in that If the variable device includes an oil pool, and the plunger pump rotates in only one direction, the oil discharge port of the valve plate of the plunger pump is connected to the oil pool.

10. The plunger pump according to claim 8, characterized in that If the variable device includes an oil pool and the plunger pump rotates in both directions, the oil ports of the plunger pump's distribution plate are connected to the oil pool through a shuttle valve.

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