A constant pressure variable regulating device and a plunger pump

Abstract

The present invention relates to the technical field of hydraulic transmission, and specifically, to a constant-pressure variable regulation device and a piston pump. The device includes a housing unit, a valve unit, and a pressure unit. An inlet oil passage, a follow-up oil passage, and a pump housing oil passage are provided on the housing of the housing unit; a buffer cavity is provided inside the housing. In the valve unit, a valve sleeve is located inside the housing; the central oil hole of the valve sleeve is coaxial with the valve sleeve; a valve core is slidably arranged in the central oil hole; the valve sleeve has a first oil port, a second oil port, and a third oil port respectively communicating with the central oil hole; the first oil port, the buffer cavity, and the inlet oil passage are sequentially communicated; the second oil port is communicated with the follow-up oil passage; the third oil port is communicated with the pump housing oil passage; during the sliding process of the valve core, the on-off of the first oil port and the second oil port, and the on-off of the second oil port and the third oil port are controlled; an elastic member of the pressure unit is located inside the housing; the elastic member applies an elastic force to the valve core to move towards the first oil port. In this way, the problem of poor stability of the constant-pressure variable regulation function of the piston pump is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic transmission, and in particular, to a constant pressure variable regulating device and a piston pump. Background Art

[0002] A hydraulic pump is the power source of a hydraulic system. The function of the hydraulic pump is to suck low-pressure oil from the oil tank and output high-pressure hydraulic energy through pressure conversion. According to the structure and working principle, hydraulic pumps can be divided into various types: piston pumps, gear pumps, vane pumps, and screw pumps. The engine-driven pumps of aircraft mostly use constant pressure variable piston pumps, which can achieve the change of flow rate from zero flow rate to full flow rate under the condition of constant pressure to meet the requirements of the aircraft hydraulic system load.

[0003] Since the piston pump is assembled on the transmission case of the aircraft engine, the vibration value transmitted from the engine to the piston pump is relatively large, and the internal control oil circuit of the piston pump has a large oil pressure pulsation value due to the suction and discharge oil structures close to the port plate of the piston pump. These directly affect the pressure stability of the constant pressure regulation function in the piston pump, and it is easy to have abnormal performance such as unstable pressure and pressure reduction of the piston pump, which limits the reliability and durability of the piston pump. Summary of the Invention

[0004] In order to solve the problem of poor stability of the constant pressure variable regulation function of the piston pump, the present invention provides a constant pressure variable regulating device and a piston pump.

[0005] In a first aspect, the present invention provides a constant pressure variable regulating device, which includes:

[0006] A housing unit, the housing unit includes a housing, and an inlet oil circuit, a follow-up oil circuit, and a pump housing oil circuit are provided on the housing; the inlet oil circuit is used to communicate with the discharge port of the piston pump; the follow-up oil circuit is used to communicate with the follow-up piston oil cavity of the piston pump; the pump housing oil circuit is used to communicate with the inner cavity of the pump housing of the piston pump; a buffer cavity is provided in the housing;

[0007] Valve unit, the valve unit includes a valve sleeve and a valve core; the valve sleeve is located within the housing; the valve sleeve is detachably connected to the housing; the valve sleeve has a central oil hole; the central oil hole is coaxial with the valve sleeve; the valve core is slidably disposed within the central oil hole; the valve sleeve has a first oil port, a second oil port, and a third oil port that are respectively in communication with the central oil hole; the first oil port, the buffer cavity, and the inlet oil passage are sequentially in communication; the second oil port is in communication with the follow-up oil passage; the third oil port is in communication with the pump housing oil passage; during the sliding process of the valve core, the on-off of the first oil port and the second oil port, and the on-off of the second oil port and the third oil port are controlled; when the first oil port and the second oil port are disconnected, the communication opening degree between the second oil port and the third oil port is a first opening degree; when the first oil port and the second oil port are in communication, the communication opening degree between the second oil port and the third oil port is a second opening degree; the second opening degree is greater than 0; the second opening degree is less than the first opening degree.

[0008] Pressure unit, the pressure unit includes an elastic member; the elastic member is located within the housing; the elastic member exerts an elastic force on the valve core to move it towards the first oil port.

[0009] In some embodiments, the valve unit further includes a valve seat; the valve seat is detachably connected to the first oil-passing end of the valve sleeve; the valve seat blocks the passage of the central oil hole towards the first oil-passing end; the axis of the first oil port is perpendicular to the axis of the central oil hole; the first oil-passing end is located between the first oil port and the buffer cavity; there is a first oil-passing groove between the valve seat and the inner wall of the housing; there is a second oil-passing groove between the first oil-passing end and the inner wall of the housing; the central oil hole, the first oil port, the second oil-passing groove, the first oil-passing groove, and the buffer cavity are sequentially in communication.

[0010] In some embodiments, there is a damping cavity within the housing; the elastic member is located within the damping cavity; the pressure unit further includes a connecting seat; the connecting seat is slidably disposed within the damping cavity; one end of the damping cavity is open; the connecting seat has a clearance fit with the inner wall of the open end of the damping cavity.

[0011] In some embodiments, the housing includes a first housing and a second housing; the valve sleeve is located within the first housing; the second housing is detachably connected to the first housing; the second housing is located within the first housing; one end of the second housing abuts one end of the valve sleeve; the end of the valve sleeve away from the second housing abuts the end face of the buffer cavity; the damping cavity is the inner cavity of the second housing.

[0012] The pressure unit further includes a push rod; the push rod is detachably connected to the second housing; the position of the push rod is adjustable; one end of the elastic member is detachably connected to the push rod, and the other end of the elastic member is detachably connected to the connecting seat.

[0013] In some embodiments, the valve core includes a first shaft section, a second shaft section, and a third shaft section integrally formed in sequence; the end of the first shaft section away from the second shaft section is detachably connected to the elastic member; the first shaft section is in sliding fit with the inner wall of the central oil hole; there is a gap between the second shaft section and the inner wall of the central oil hole; the second shaft section includes a first diameter section and a second diameter section; the diameter of the first diameter section is smaller than the diameter of the second diameter section;

[0014] The third shaft section has a first state and a second state; the first state includes the third shaft section being in sliding fit with the inner wall of the central oil hole; the second state includes the third shaft section being located at the intersection position of the second oil port and the central oil hole, and the third shaft section being separated from the inner wall of the central oil hole; the end of the third shaft section away from the second shaft section faces the first oil port;

[0015] When the third shaft section is in the first state, the first oil port and the second oil port are disconnected, and the second diameter section is located at the intersection position of the second oil port and the central oil hole; when the third shaft section is in the second state, the first oil port and the second oil port are communicated, and the second diameter section is located in the central oil hole between the second oil port and the third oil port.

[0016] In some embodiments, the valve core further includes a fourth shaft section, and the end of the third shaft section away from the second shaft section is integrally formed with the fourth shaft section; there is a gap between the fourth shaft section and the inner wall of the central oil hole.

[0017] In some embodiments, the opening diameter of the third oil port gradually decreases in the direction away from the central oil hole.

[0018] In some embodiments, the second oil port is located on the first side of the valve sleeve; there are multiple third oil ports; the opening diameter of the third oil port close to the first side of the valve sleeve gradually decreases in the direction away from the central oil hole; the third oil port facing away from the first side of the valve sleeve is a cylindrical hole.

[0019] In a second aspect, the present invention discloses a plunger pump, the plunger pump includes the constant pressure variable adjustment device according to any one of the above embodiments; the plunger pump further includes:

[0020] The plunger pump body, the plunger pump body having an oil discharge port, a follow-up piston oil chamber, and a pump housing inner cavity; the follow-up piston oil chamber is used for constant-pressure variable adjustment of the oil discharge port of the plunger pump body;

[0021] The inlet oil circuit of the constant-pressure variable adjustment device is communicated with the oil discharge port; the follow-up oil circuit is communicated with the follow-up piston oil chamber; the pump housing oil circuit is communicated with the pump housing inner cavity.

[0022] In some embodiments, at least part of the housing of the constant-pressure variable adjustment device is integrally formed with the pump housing of the plunger pump body.

[0023] To solve the problem of poor stability of the constant-pressure variable adjustment function of the plunger pump, the present invention has the following advantages:

[0024] First, by utilizing the buffering effect of the buffer cavity, the pressure pulsation of the high-pressure oil liquid input into the inlet oil circuit is initially attenuated to ensure the stable pressure transmission of the oil liquid. Secondly, by using the third oil port for pressure relief, the damping after the valve core is opened can be increased, so that the valve core can maintain a relatively stable position during the sliding process, and it is not easy to cause a sudden increase in the communication opening degree between the first oil port and the second oil port. Furthermore, the pressure transmission of the high-pressure oil liquid input into the inlet oil circuit to the follow-up piston oil chamber is effectively ensured, and the unstable influence of the oil liquid pressure pulsation and the engine vibration on the constant-pressure variable adjustment is reduced. Description of the Drawings

[0025] Figure 1 Shows a schematic diagram of a constant-pressure variable adjustment device of an embodiment;

[0026] Figure 2 Shows Figure 1 An enlarged schematic view of area A of the constant-pressure variable adjustment device in the embodiment.

[0027] Reference Signs: 10 housing unit; 11 housing; 111 first housing; 112 second housing; 12 inlet oil circuit; 13 follow-up oil circuit; 14 pump housing oil circuit; 15 buffer cavity; 20 valve unit; 21 valve sleeve; 22 valve core; 221 first shaft section; 222 second shaft section; 2221 first diameter section; 2222 second diameter section; 223 third shaft section; 224 fourth shaft section; 23 central oil hole; 24 first oil port; 25 second oil port; 26 third oil port; 27 valve seat; 30 pressure unit; 31 elastic member; 32 connecting seat; 33 ejector rod; 34 pressure regulating screw; 35 locking nut. Detailed Description of the Invention

[0028] Now, the content of the present disclosure will be described with reference to several exemplary embodiments. It should be understood that these embodiments are described only to enable those of ordinary skill in the art to better understand and thus implement the content of the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0029] As used herein, the term "including" and its variants are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "based at least in part on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like is based on the orientation or position relationship shown in the accompanying drawings. These terms are mainly for better describing the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation. In addition, in addition to being used to indicate an orientation or position relationship, some of the above terms may also be used to indicate other meanings, such as the term "upper" may also be used to indicate a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to the specific circumstances. In addition, the terms "install", "set", "provided with", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0030] Most of the existing constant-pressure variable piston pumps are installed on the transmission casing of the aircraft engine. However, due to the large vibration transmitted to the piston pump when the engine is running, and the piston pump realizes the constant-pressure variable adjustment function through the built-in constant-pressure variable adjustment device, the control oil circuit of this function is close to the oil suction and discharge structure of the distribution plate, and the pressure pulsation value of the oil is large, which affects the constant-pressure variable adjustment function of the piston pump, and is prone to performance abnormalities such as unstable or even reduced pressure of the piston pump. Therefore, in order to improve the reliability of the constant-pressure variable adjustment function of the piston pump and improve the durability of the piston pump, this embodiment discloses a constant-pressure variable adjustment device. In this embodiment, Figure 1As shown in the figure, the constant pressure variable regulating device may include a housing unit 10, a valve unit 20, and a pressure unit 30. The housing unit 10 includes a housing 11, on which an inlet oil passage 12, a follow-up oil passage 13, and a pump housing oil passage 14 are provided. The inlet oil passage 12 is used to communicate with the oil discharge port of the piston pump, and the oil discharge port can input high-pressure oil into the inlet oil passage 12. The follow-up oil passage 13 is used to communicate with the follow-up piston oil cavity of the piston pump, and the swash plate of the piston pump can adjust its own inclination angle according to the change of the oil pressure in the follow-up piston oil cavity. The pump housing oil passage 14 is used to communicate with the inner cavity of the pump housing of the piston pump. A buffer cavity 15 is arranged in the housing 11.

[0031] As Figure 1 shown in the figure, the valve unit 20 may include a valve sleeve 21 and a valve core 22. The valve sleeve 21 is located inside the housing 11. The valve sleeve 21 is detachably connected to the housing 11. The valve sleeve 21 has a central oil hole 23. The central oil hole 23 is coaxial with the valve sleeve 21. The valve core 22 is slidably arranged in the central oil hole 23. The valve sleeve 21 has a first oil port 24, a second oil port 25, and a third oil port 26 that communicate with the central oil hole 23 respectively. The first oil port 24, the buffer cavity 15, and the inlet oil passage 12 are connected in sequence. The second oil port 25 communicates with the follow-up oil passage 13. The third oil port 26 communicates with the pump housing oil passage 14. During the sliding process of the valve core 22, the on-off of the first oil port 24 and the second oil port 25, and the on-off of the second oil port 25 and the third oil port 26 are controlled. When the first oil port 24 and the second oil port 25 are in the disconnected state, the communication opening degree between the second oil port 25 and the third oil port 26 is the first opening degree. When the first oil port 24 and the second oil port 25 are in the connected state, the communication opening degree between the second oil port 25 and the third oil port 26 is the second opening degree. The second opening degree is greater than 0. The second opening degree is less than the first opening degree. Through the above settings, the high-pressure oil enters the buffer cavity 15 from the inlet oil passage 12, and the buffer cavity 15 attenuates the pressure pulsation of the oil. The oil in the buffer cavity 15 then enters the central oil hole 23 through the first oil port 24. When the oil pressure at the first oil port 24 of the valve sleeve 21 is greater than the opening pressure of the valve core 22, the oil drives the valve core 22 to slide in a direction away from the first oil port 24. When the valve core 22 slides to a position where the first oil port 24 and the second oil port 25 are connected, the oil can enter the follow-up oil passage 13 through the second oil port 25. The follow-up oil passage 13 automatically adjusts the displacement according to the stable change of the oil pressure at the oil discharge port of the piston pump. For example, the displacement can be adjusted by adjusting the swash plate angle. At the same time, since the second oil port 25 and the third oil port 26 maintain the communication opening degree of the second opening degree at this time, part of the oil can enter the pump housing oil passage 14 through the third oil port 26, so that the high-pressure oil at the oil discharge port of the piston pump can be relieved through the third oil port 26, reducing the influence of the oil pressure pulsation on the oil pressure in the follow-up oil passage 13, thereby improving the stability of the constant pressure variable regulation.

[0032] As Figure 1As shown, the pressure unit 30 may include an elastic member 31. The elastic member 31 is located within the housing 11. The elastic member 31 exerts an elastic force on the valve core 22 to move it towards the first oil port 24. Thus, the elastic force of the elastic member 31 provides an opening pressure for the valve core 22. This can cooperate with the pressure relief of the third oil port 26, so that when the valve core 22 slides to the position where the first oil port 24 communicates with the second oil port 25, it remains stable and is not likely to cause a sudden increase in the communication opening degree between the first oil port 24 and the second oil port 25.

[0033] Meanwhile, the buffer cavity 15 may be provided at one end of the first oil port 24 away from the central oil hole 23. The first oil port 24, the second oil hole, and the third oil port 26 are sequentially spaced along the axial direction of the valve sleeve 21. The third oil port 26 may be located near one end of the central oil hole 23 close to the elastic member 31. Due to the space limitation inside the valve sleeve 21, it is difficult to add an additional buffer cavity 15 inside the valve sleeve 21. Therefore, setting the buffer cavity 15 inside the housing 11, that is, on the outer side of one end of the valve sleeve 21, can improve the space utilization rate and increase the distance between the buffer cavity 15 and the follow-up oil circuit 13, reducing the influence of pressure pulsation on the oil pressure of the follow-up oil circuit 13. In the case where the pressure pulsation is relatively dense, the oil pressure in the buffer cavity 15 may accumulate and the oil pressure is difficult to release, causing the continuous transmission of pressure pulsation. In contrast, in the present invention, the third oil port 26 is connected to the pump housing oil circuit 14 for pressure relief, which can achieve a continuous pressure pulsation attenuation effect and is not likely to cause the accumulation and further transmission of pressure pulsation. Therefore, the second opening degree design of the buffer cavity 15 and the third oil port 26 forms a multi-stage pressure pulsation attenuation. Thus, by cooperating with the buffering effect of the buffer cavity 15 and the pressure relief effect of the third oil port 26, it effectively ensures the stable pressure transmission of the oil in the inlet oil circuit 12 to the follow-up oil circuit 13, reduces the unstable influence of oil pressure pulsation and engine vibration on the constant pressure variable regulation function, and ensures the dynamic sensing accuracy of the swash plate of the piston pump to adjust its own tilt angle through the oil pressure in the follow-up piston oil cavity.

[0034] In this embodiment, as Figure 1As shown, the valve unit 20 further includes a valve seat 27. The valve seat 27 is detachably connected to the first oil-passing end of the valve sleeve 21, and the first oil-passing end is the end of the valve sleeve 21 away from the elastic member 31. The valve seat 27 blocks the passage of the central oil hole 23 toward the first oil-passing end. The axis of the first oil port 24 is perpendicular to the axis of the central oil hole 23, and a plurality of first oil ports 24 can be arranged along the circumferential direction of the central oil hole 23. The first oil-passing end is located between the first oil port 24 and the buffer cavity 15. There may be a first oil-passing groove between the valve seat 27 and the inner wall of the housing 11. There may be a second oil-passing groove between the first oil-passing end and the inner wall of the housing 11. The central oil hole 23, the first oil port 24, the second oil-passing groove, the first oil-passing groove, and the buffer cavity 15 are communicated in sequence. Through the above settings, the valve seat 27 can play a positioning role during the assembly of the valve sleeve 21, while preventing the oil in the buffer cavity 15 from directly entering the central oil hole 23 through the first oil-passing end, thereby ensuring the stability of the sliding of the valve core 22. Moreover, the oil path formed by the sequential communication of the central oil hole 23, the first oil port 24, the second oil-passing groove, the first oil-passing groove, and the buffer cavity 15 extends the path of the oil in the buffer cavity 15 entering the central oil hole 23, slowing down the pressure pulsation of the oil. The space formed by the first oil-passing groove and the second oil-passing groove can also play a certain buffering role, thereby reducing the influence of the pressure pulsation of the oil and the vibration of the engine on the stability of the constant-pressure variable regulation function.

[0035] In this embodiment, as Figure 1 shown, there is a damping cavity in the housing 11, and the damping cavity can be located at the end of the valve sleeve 21 away from the buffer cavity 15. The elastic member 31 is located in the damping cavity. The pressure unit 30 may further include a connecting seat 32. The connecting seat 32 is slidably arranged in the damping cavity. One end of the damping cavity is an opening. The connecting seat 32 is in clearance fit with the inner wall of the opening of the damping cavity. One end of the connecting seat 32 can abut against the elastic member 31, and the other end can abut against the end of the valve core 22 away from the first oil port 24. Through the damping cavity and the elastic member 31, the damping force of the valve core 22 sliding toward the connecting seat 32 can be increased. The clearance fit between the connecting seat 32 and the damping cavity can facilitate the compression and exhaust of the oil in the damping cavity. The abutting portion between the connecting seat 32 and the valve core 22 can be a spherical surface fit to improve the flexibility of the valve core 22 sliding under the elastic force of the elastic member 31. Through the above settings, the sudden increase in the opening degree of the communication between the first oil port 24 and the second oil port 25 or the opening degree of the communication between the second oil port 25 and the third oil port 26 can be avoided during the sliding process of the valve core 22. When the valve core 22 and the valve sleeve 21 are opened and the high-pressure oil in the inlet oil path 12 enters the follow-up piston oil cavity, part of the oil is leaked into the pump housing cavity through the third oil port 26, which can improve the damping effect after the valve core 22 is opened and enhance the stability of the valve core 22 sliding axially along the central oil hole 23.

[0036] In this embodiment, as Figure 1As shown, the housing 11 may include a first housing 111 and a second housing 112. The valve sleeve 21 is located within the first housing 111. The second housing 112 is detachably connected to the first housing 111. The second housing 112 is located within the first housing 111, that is, one end of the second housing 112 extends into the first housing 111. One end of the second housing 112 abuts against one end of the valve sleeve 21. The end of the valve sleeve 21 away from the second housing 112 abuts against the end face of the buffer cavity 15. Thus, the valve sleeve 21 is fixed at a set position within the first housing 111 by the abutment of the second housing 112. The damping cavity is the inner cavity of the second housing 112.

[0037] The pressure unit 30 further includes a push rod 33. The push rod 33 is detachably connected to the second housing 112. The position of the push rod 33 is adjustable. By adjusting the position of the push rod 33, the compression amount of the elastic member 31 within the damping cavity can be changed, providing different degrees of damping force for the sliding of the valve core 22, and further changing the oil pressure required for the valve core 22 to open the communication between the first oil port 24 and the second oil port 25. One end of the elastic member 31 is detachably connected to the push rod 33, and the other end of the elastic member 31 is detachably connected to the connecting seat 32. Through the above arrangement, it is convenient for the structural dimension design of the constant pressure variable adjustment device and convenient for assembly.

[0038] In some other embodiments, as Figure 1 shown, the pressure unit 30 may further include a pressure regulating screw 34 and a locking nut 35. The pressure regulating screw 34 is threadedly connected to the end of the second housing 112 away from the damping cavity. One end of the pressure regulating screw 34 abuts against the end of the push rod 33 away from the elastic member 31, and the other end is threadedly connected to the locking nut 35. Thus, the position of the push rod 33 in the axial direction can be adjusted through the pressure regulating screw 34, and the position of the push rod 33 is fixed by the locking nut 35, realizing that the push rod 33 remains stable after adjusting the damping force of the elastic member 31.

[0039] In this embodiment, as Figure 1 、 Figure 2 shown, the valve core 22 may include a first shaft section 221, a second shaft section 222, and a third shaft section 223 integrally formed in sequence. The end of the first shaft section 221 away from the second shaft section 222 is detachably connected to the elastic member 31. The first shaft section 221 slidably fits with the inner wall of the central oil hole 23. There is a gap between the second shaft section 222 and the inner wall of the central oil hole 23. The second shaft section 222 includes a first diameter section 2221 and a second diameter section 2222. The diameter of the first diameter section 2221 is smaller than the diameter of the second diameter section 2222. The diameter of the second diameter section 2222 may be smaller than the diameter of the third shaft section 223.

[0040] The third shaft segment 223 has a first state and a second state. The first state includes that the third shaft segment 223 is in sliding fit with the inner wall of the central oil hole 23. The second state includes that the third shaft segment 223 is located at the intersection position of the second oil port 25 and the central oil hole 23, and the third shaft segment 223 is separated from the inner wall of the central oil hole 23. One end of the third shaft segment 223 far from the second shaft segment 222 is arranged towards the first oil port 24. That is, the diameter of the third shaft segment 223 matches the aperture of the central oil hole 23, and the length of the third shaft segment 223 along the axial direction of the central oil hole 23 is smaller than the aperture of the second oil port 25.

[0041] When the third shaft segment 223 is in the first state, the first oil port 24 is disconnected from the second oil port 25, and the second diameter segment 2222 is located at the intersection position of the second oil port 25 and the central oil hole 23. When the third shaft segment 223 is in the second state, the first oil port 24 is communicated with the second oil port 25, and the second diameter segment 2222 is located in the central oil hole 23 between the second oil port 25 and the third oil port 26.

[0042] Through the above settings, the distance between the first diameter segment 2221 and the inner wall of the central oil hole 23 can be controlled by adjusting the diameter of the first diameter segment 2221, and the distance between the second diameter segment 2222 and the inner wall of the central oil hole 23 can be controlled by adjusting the diameter of the second diameter segment 2222. The difference in the diameters of the first diameter segment 2221 and the second diameter segment 2222 can directly reflect the difference in the first opening degree and the second opening degree. Thus, the flow rate of the oil when the oil is relieved through the third oil port 26 can be controlled, avoiding the influence of too low oil pressure on the accuracy of the swash plate to adjust its own tilt angle according to the oil in the follow-up piston oil cavity. Furthermore, during the sliding process of the spool 22, when the third shaft segment 223 is in the first state, the second oil port 25 and the third oil hole are at the first opening degree, and when the third shaft segment 223 is in the second state, the second oil port 25 and the third oil hole are at the second opening degree. This enables the oil to enter the follow-up oil path 13 while being relieved through the third oil port 26, ensuring the stability of the position of the spool 22 and reducing the influence of oil pressure pulsation and engine vibration on the constant pressure variable regulation function.

[0043] In this embodiment, as Figure 1 、 Figure 2 shown, the spool 22 may further include a fourth shaft segment 224, and the end of the third shaft segment 223 far from the second shaft segment 222 is integrally formed with the fourth shaft segment 224. There is a distance between the fourth shaft segment 224 and the inner wall of the central oil hole 23. By controlling the distance between the fourth shaft segment 224 and the inner wall of the central oil hole 23, the oil flow rate from the first oil port 24 through the central oil hole 23 into the second oil port 25 can be controlled, avoiding the oil pressure oscillation in the second oil port 25 caused by too large oil flow rate.

[0044] In some other embodiments, the fourth shaft segment 224 may include a third diameter segment and a fourth diameter segment. The third shaft segment 223, the third diameter segment, and the fourth diameter segment are integrally formed in sequence. The fourth diameter segment is in clearance fit with the inner wall of the central oil hole 23. A third oil passage groove may be axially formed in the fourth diameter segment along the central oil hole 23. A plurality of third oil passage grooves may be circumferentially spaced along the fourth diameter segment. The diameter of the fourth diameter segment may be greater than or equal to the second diameter segment 2222, and the diameter of the third diameter segment may be less than or equal to the diameter of the first diameter segment 2221. Thus, a cavity is formed between the outer peripheral wall of the third diameter segment and the inner wall of the central oil hole 23, so that the oil fluid in the first oil port 24 is buffered after passing through the third oil passage groove, and the pressure pulsation of the oil fluid input into the second oil port 25 is slowed down.

[0045] In this embodiment, the opening diameter of the third oil port 26 may gradually decrease in the direction away from the central oil hole 23, so that the third oil port 26 forms a flared opening in the valve sleeve 21, which helps to buffer the oil fluid in the second oil port 25 when the oil fluid is relieved to the third oil port 26, and can cooperate with the buffer cavity 15 to achieve a secondary buffer effect under the space limitation of the valve sleeve 21.

[0046] In this embodiment, as Figure 1 shown, the second oil port 25 is located on the first side of the valve sleeve 21, and the first side may be the side of the valve sleeve 21 close to the follow-up oil passage 13. There are a plurality of third oil ports 26, and the third oil ports 26 may be circumferentially spaced along the valve sleeve 21. The opening diameter of the third oil port 26 close to the first side of the valve sleeve 21 gradually decreases in the direction away from the central oil hole 23. The third oil port 26 facing away from the first side of the valve sleeve 21 is a cylindrical hole. Since the second oil port 25 close to the first side of the valve sleeve 21 is communicated with the follow-up oil passage 13, in order to avoid excessive pressure pulsation of the oil fluid in the follow-up oil passage 13, it is necessary for the third oil port 26 close to the first side of the valve sleeve 21 to buffer the oil fluid while relieving the pressure. Therefore, considering the space limitation in the valve sleeve 21, the third oil port 26 close to the first side of the valve sleeve 21 can be set as a flared opening. And the third oil port 26 facing away from the first side of the valve sleeve 21 being a cylindrical hole can reduce the processing difficulty of the valve sleeve 21.

[0047] In this embodiment, this embodiment discloses a piston pump. The piston pump may include the constant pressure variable adjustment device of any one of the above embodiments. The piston pump may further include a piston pump main body, and the piston pump main body may have an oil discharge port, a follow-up piston oil cavity, and a pump housing inner cavity. The follow-up piston oil cavity is used for performing constant pressure variable adjustment on the oil discharge port of the piston pump main body, so that the swash plate of the piston pump can adjust its own tilt angle according to the oil fluid pressure in the follow-up piston oil cavity, thereby controlling the oil fluid flow rate of the oil discharge port.

[0048] The inlet oil passage 12 of the constant pressure variable regulating device is communicated with the oil drain port. The follow-up oil passage 13 is communicated with the follow-up piston oil cavity. The pump housing oil passage 14 is communicated with the inner cavity of the pump housing. Thus, the constant pressure variable regulating device can be used to reduce the influence of the oil pressure pulsation at the oil drain port and the engine vibration on the constant pressure variable regulating function, so that the oil pressure of the oil input into the follow-up piston oil cavity through the follow-up oil passage 13 is stable, and the reliability and durability of the plunger pump are improved.

[0049] In the present invention, components and structures such as a valve sleeve 21, a push rod 33, a buffer cavity 15, a damping cavity, etc. are introduced into the traditional constant pressure variable structure of a hydraulic pump, greatly improving the stability of the spool 22 in the constant pressure variable regulating device and the ability to withstand high engine vibration conditions. Compared with the traditional constant pressure variable mechanism of a hydraulic pump, the pressure stability of the constant pressure regulating function is improved, and the reliability and durability of the hydraulic pump are enhanced. Moreover, the present invention is simple, compact, low-cost, easy to transform on the basis of the existing structure, has strong applicability and a wide range of application scenarios.

[0050] In this embodiment, at least part of the housing 11 of the constant pressure variable regulating device can be integrally formed with the pump housing of the plunger pump body. That is, the outer peripheral wall of the first housing 111 can be integrally formed with the pump housing, and the constant pressure variable regulating device can be arranged in the inner cavity of the pump housing, thereby reducing the production and assembly difficulty of the constant pressure variable regulating device and simplifying the structure.

[0051] It should be understood that the "this embodiment" mentioned in the present invention refers to the technical points described currently. Multiple "this embodiments" can be the same embodiment or different embodiments.

[0052] Those of ordinary skill in the art can understand that the above embodiments are specific cases for implementing the present disclosure, and in practical applications, various changes can be made in form and details without departing from the scope of the present disclosure.

Claims

1. A constant pressure variable adjustment device, characterized in that The constant pressure variable adjustment device includes: A housing unit, the housing unit includes a housing, and an inlet oil passage, a follow-up oil passage, and a pump housing oil passage are provided on the housing; the inlet oil passage is used to connect to the oil discharge port of the plunger pump; the follow-up oil passage is used to connect to the follow-up piston oil chamber of the plunger pump; the pump housing oil passage is used to connect to the inner cavity of the pump housing of the plunger pump; a buffer cavity is provided inside the housing; A valve unit, the valve unit includes a valve sleeve and a valve core; the valve sleeve is located inside the housing; the valve sleeve is detachably connected to the housing; the valve sleeve has a central oil hole; the central oil hole is coaxial with the valve sleeve; the valve core is slidably arranged in the central oil hole; the valve sleeve has a first oil port, a second oil port, and a third oil port that are respectively communicated with the central oil hole; the first oil port, the buffer cavity, and the inlet oil passage are sequentially communicated; the second oil port is communicated with the follow-up oil passage; the third oil port is communicated with the pump housing oil passage; during the sliding process of the valve core, it controls the on-off of the first oil port and the second oil port, and the on-off of the second oil port and the third oil port; when the first oil port and the second oil port are disconnected, the communication opening degree between the second oil port and the third oil port is a first opening degree; when the first oil port and the second oil port are communicated, the communication opening degree between the second oil port and the third oil port is a second opening degree; the second opening degree is greater than 0; the second opening degree is less than the first opening degree; A pressure unit, the pressure unit includes an elastic member; the elastic member is located inside the housing; the elastic member applies an elastic force to the valve core to move it towards the first oil port; The valve core includes a first shaft section, a second shaft section, and a third shaft section that are integrally formed in sequence; the end of the first shaft section away from the second shaft section is detachably connected to the elastic member; the first shaft section is slidably attached to the inner wall of the central oil hole; there is a gap between the second shaft section and the inner wall of the central oil hole; the second shaft section includes a first diameter section and a second diameter section; the diameter of the first diameter section is smaller than the diameter of the second diameter section; The third shaft section has a first state and a second state; the first state includes that the third shaft section is slidably attached to the inner wall of the central oil hole; the second state includes that the third shaft section is located at the intersection position of the second oil port and the central oil hole, and the third shaft section is separated from the inner wall of the central oil hole; one end of the third shaft section away from the second shaft section faces the first oil port; When the third shaft section is in the first state, the first oil port and the second oil port are disconnected, and the second diameter section is located at the intersection position of the second oil port and the central oil hole; when the third shaft section is in the second state, the first oil port and the second oil port are communicated, and the second diameter section is located in the central oil hole between the second oil port and the third oil port.

2. The constant pressure variable adjustment device according to claim 1, wherein The valve unit further includes a valve seat; the valve seat is detachably connected to the first oil-passing end of the valve sleeve; the valve seat blocks the passage of the central oil hole facing the first oil-passing end; the axis of the first oil port is perpendicular to the axis of the central oil hole; the first oil-passing end is located between the first oil port and the buffer cavity; there is a first oil-passing groove between the valve seat and the inner wall of the housing; there is a second oil-passing groove between the first oil-passing end and the inner wall of the housing; the central oil hole, the first oil port, the second oil-passing groove, the first oil-passing groove and the buffer cavity are communicated in sequence.

3. The constant-pressure variable adjustment device according to claim 1, wherein a damping cavity is provided in the housing; the elastic member is located in the damping cavity; the pressure unit further includes a connecting seat; the connecting seat is slidably arranged in the damping cavity; one end of the damping cavity is open; the connecting seat is in clearance fit with the inner wall of the opening of the damping cavity.

4. The constant-pressure variable adjustment device according to claim 3, wherein the housing includes a first housing and a second housing; the valve sleeve is located in the first housing; the second housing is detachably connected to the first housing; the second housing is located inside the first housing; one end of the second housing abuts against one end of the valve sleeve; the end of the valve sleeve away from the second housing abuts against the end face of the buffer cavity; the damping cavity is the inner cavity of the second housing; the pressure unit further includes a push rod; the push rod is detachably connected to the second housing; the position of the push rod is adjustable; one end of the elastic member is detachably connected to the push rod, and the other end of the elastic member is detachably connected to the connecting seat.

5. The constant-pressure variable adjustment device according to claim 1, wherein the valve core further includes a fourth shaft section, and the end of the third shaft section away from the second shaft section is integrally formed with the fourth shaft section; there is a distance between the fourth shaft section and the inner wall of the central oil hole.

6. The constant-pressure variable adjustment device according to claim 1, wherein the opening diameter of the third oil port gradually decreases in the direction away from the central oil hole.

7. The constant-pressure variable adjustment device according to claim 1, wherein the second oil port is located on the first side of the valve sleeve; there are multiple third oil ports; the opening diameter of the third oil port close to the first side of the valve sleeve gradually decreases in the direction away from the central oil hole; the third oil port away from the first side of the valve sleeve is a cylindrical hole.

8. A piston pump, wherein the piston pump includes: a piston pump main body, the piston pump main body has an oil discharge port, a follow-up piston oil cavity and a pump housing inner cavity; the follow-up piston oil cavity is used for constant-pressure variable adjustment of the oil discharge port of the piston pump main body; the constant-pressure variable adjustment device according to any one of claims 1-7; the inlet oil circuit of the constant-pressure variable adjustment device is communicated with the oil discharge port; the follow-up oil circuit is communicated with the follow-up piston oil cavity; the pump housing oil circuit is communicated with the pump housing inner cavity.

9. The piston pump according to claim 8, wherein The housing of the constant pressure variable regulating device is integrally formed with at least part of the pump housing of the plunger pump body.

Images