A piston pump with force-balanced swashplate distribution

Abstract

A force-balanced swashplate plunger pump includes a hollow pump body with one open end. An end cap is installed at the open end of the pump body, and an inlet and outlet are spaced apart at the closed end, communicating with its internal cavity. A main shaft, with one end extending into the pump body cavity, is rotatably connected to the end cap. One end of the main shaft, located within the pump body, is eccentrically connected to a swashplate, with one end slidingly engaged with the closed end of the pump body and the other end inclined. The swashplate has a small head on the side closer to the main shaft and a large head on the other side. A balancing groove is provided on the outer circumference of the large head of the swashplate, aligning the center of mass of the swashplate with the axis of the main shaft. An annular boss, movably fitted onto the main shaft, is provided inside the end cap. An upper sliding plate, coaxially fitted onto the main shaft, is located between the annular boss and the swashplate. One end of the upper sliding plate is universally engaged with the annular boss, and the other end is slidably engaged with the inclined end of the swashplate. This invention avoids the rotational movement of the plunger following the rotor assembly in the prior art, eliminating lateral forces.

Description

Technical Field

[0001] This invention relates to the field of plunger pump technology, and in particular to a plunger pump with force-balanced swashplate flow distribution. Background Technology

[0002] As is well known, piston pumps are the main devices in hydraulic systems that achieve high-pressure output. They have high output pressure and can maintain high volumetric efficiency and overall efficiency even under high pressure. In traditional piston pumps, the drive shaft drives the rotor assembly to rotate, and a swashplate at a fixed angle drives the pistons in the piston holes on the rotor to reciprocate, completing the oil suction and discharge process. However, the traditional piston pump structure has some shortcomings, such as: 1. During operation, the rotor is subjected to lateral forces from the pistons, generating an overturning moment that makes the rotor body subject to complex forces; 2. Under high-speed rotation conditions, the moment of inertia is large and there is a large unstable centrifugal force; 3. Under high-speed rotation conditions, the pistons will experience excessive speed and acceleration, resulting in poor stability; 4. There are many friction pairs inside the pump, resulting in high relative speeds and low reliability. These defects are problems that urgently need to be solved by those skilled in the art.

[0003] Chinese patent (publication number: CN105090008B) discloses an axial piston pump. The swashplate of this patent is connected to the piston assembly through a cross-shaped rocker plate. Both ends of the piston have spherical structures, and the force is in a two-force bar state, which greatly reduces the radial force on the piston orifice. The piston assembly does not rotate with the rotor, and the lateral force is small. However, the structure of this patent is complex, difficult to assemble, and has high production cost. In addition, a distribution valve is still required, and the pump body volume cannot be further reduced. The swashplate will generate a large centrifugal force during operation. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention discloses a piston pump with force-balanced swashplate distribution.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A force-balanced swashplate plunger pump includes a hollow pump body with one open end. An end cap is installed at the open end of the pump body, and an oil inlet and an oil outlet are spaced apart at the closed end and communicate with its internal cavity. A main shaft with one end extending into the pump body cavity is rotatably connected to the end cap. A swashplate with one end slidingly engaged with the closed end of the pump body and the other end inclined is eccentrically connected to one end of the main shaft inside the pump body. The side of the swashplate closer to the main shaft is a small head, and the other side is a large head. The outer circumference of the large head of the swashplate is provided with a balance groove that makes the center of mass of the swashplate coincide with the axis of the main shaft. An annular boss is provided on the inner side of the end cap and is movably fitted with the main shaft. An upper sliding plate is provided between the annular boss and the swashplate and is movably fitted with the main shaft on the same axis. One end of the upper sliding plate is universally engaged with the annular boss, and the other end is slidably engaged with the inclined end of the swashplate.

[0007] Multiple plunger assemblies are arranged circumferentially between the upper sliding plate and the end cover. Each plunger assembly includes a plunger tube with open ends. Both ends of the plunger tube are movably fitted with ball sleeves, which are universally connected to the upper sliding plate and the end cover, respectively. A limiting mechanism is provided between one side of the upper sliding plate and the pump body to prevent the upper sliding plate from rotating. The upper sliding plate is provided with oil passage holes at the positions corresponding to the plunger assemblies. These oil passage holes can be covered by the large head of the swashplate and exposed on the outside of the small head of the swashplate. The oil passage holes are connected to the plunger tubes.

[0008] The large head of the inclined plate is provided with a high-pressure oil chamber that can communicate with the oil passage, and the other end is provided with an oil discharge chamber in the shape of an 8. One circular cavity of the oil discharge chamber is connected to the high-pressure oil chamber, and the other circular cavity is coaxial with the main shaft and connected to the oil outlet.

[0009] Preferably, the high-pressure oil chamber is an arc-shaped cavity structure whose center coincides with the axis of the main shaft.

[0010] Preferably, the closed end of the pump body is provided with a wear-resistant disc that slides with the swashplate, and a pin is provided between the wear-resistant disc and the closed end of the pump body. The wear-resistant disc is provided with a ring sleeve that is coaxially and tightly inserted with the oil outlet at the position corresponding to the oil outlet.

[0011] Preferably, the oil outlet is coaxial with the main shaft, and the swash plate is provided with an oil drain pipe that is coaxially and rotatably connected to the wear-resistant disc ring, and the oil drain pipe is connected to the oil drain chamber.

[0012] Preferably, a copper sleeve is provided between the oil drain pipe and the wear-resistant disc ring, and reinforcing ribs are provided inside the oil drain pipe.

[0013] Preferably, the upper sliding plate is provided with a lower sliding plate at the end opposite to the swashplate, and a pressure plate is provided on the inner side of the end cover, which is coaxially sleeved with the annular boss of the end cover. Spherical cavities that are universally matched with the corresponding ball sleeves are provided at the positions of the plunger assemblies between the lower sliding plate and the upper sliding plate, and between the pressure plate and the end cover.

[0014] Preferably, the sliding plate and the annular boss of the end cover are connected by a support ball joint, the support ball joint is movably sleeved with the main shaft, and is correspondingly and fastened to the annular boss of the end cover.

[0015] Preferably, the limiting mechanism includes a limiting pin disposed on the inner wall of the pump body, and the upper sliding plate is provided with a sliding groove that slides with the limiting pin; or the limiting pin is disposed on the upper sliding plate, and the inner wall of the pump body is provided with a sliding groove that slides with the limiting pin.

[0016] Preferably, a sealing ring is provided between the pump body and the end cover, and an oil seal is provided between the main shaft and the end cover.

[0017] Preferably, the main shaft and the end cover are rotatably connected by bearings.

[0018] The plunger pump with force-balanced swashplate flow distribution disclosed in this invention has the following beneficial effects due to the adoption of the technical solution described above:

[0019] 1. This invention adopts a swashplate structure, eliminating the distribution plate structure and realizing the integration of the functions of the swashplate and the distribution plate;

[0020] 2. This invention achieves force and torque balance of the swashplate through the design of the oil drain chamber structure, thereby optimizing the stress on the relevant structures;

[0021] 3. In this invention, the centroid of the swashplate coincides with the axis of the main shaft, reducing the centrifugal force of the swashplate rotation;

[0022] 4. The plunger tube structure of this invention is simple and easy to process; the two ends of the plunger assembly are connected by a ball joint, eliminating lateral forces and providing better stress distribution, enabling higher speed operation; the plunger tube moves freely between the two ball sleeves, and the pressure on both sides of the plunger tube is balanced, avoiding excessive axial velocity and acceleration of the plunger tube under high-speed operation, thus improving stability; the plunger tube structure has good stress distribution, and the length of the plunger tube can be greatly reduced, only requiring sufficient sealing length, resulting in a more compact structure;

[0023] 5. In this invention, the plunger tube follows the rotation of the rotor assembly, which is a common feature in the prior art. This allows the plunger assembly to swing within a small range, resulting in a smaller centrifugal force.

[0024] 6. This invention eliminates the rotor structure and slipper structure, resulting in a smaller moment of inertia, fewer friction pairs, and significantly improved reliability;

[0025] 7. The relative motion speed between the friction pairs of this invention is low, resulting in high reliability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the swashplate structure;

[0028] Figure 3 This is a schematic diagram of the swashplate structure;

[0029] Figure 4 This is the front view of the swashplate;

[0030] Figure 5 This is a schematic diagram of the plunger assembly.

[0031] In the diagram: 1. Pump body; 2. End cover; 3. Oil inlet; 4. Oil outlet; 5. Main shaft; 6. Swashplate; 7. Upper sliding plate; 8. Piston tube; 9. Balance groove; 10. Ball sleeve; 11. Oil passage hole; 12. High-pressure oil chamber; 13. Oil discharge chamber; 14. Limiting mechanism; 15. Wear-resistant disc; 16. Pin; 17. Copper sleeve; 18. Lower sliding plate; 19. Pressure plate; 20. Support ball joint; 21. Sealing ring; 22. Oil seal; 23. Bearing; 24. Oil discharge pipe. Detailed Implementation

[0032] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "rear", "left", "right" indicating the orientation or positional relationship, they are only corresponding to the drawings of this application for the convenience of describing the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation.

[0033] Example 1:

[0034] Combined with appendix Figures 1-5 A force-balanced swashplate plunger pump includes a hollow pump body 1 with one open end. An end cap 2 is installed on the open end of the pump body 1, and an oil inlet 3 and an oil outlet 4 are provided at intervals at the closed end, which communicate with the inner cavity of the pump body 1, so that liquid can enter the inner cavity of the pump body 1 through the oil inlet 3.

[0035] The end cover 2 is rotatably connected to a main shaft 5, one end of which extends into the inner cavity of the pump body 1. In use, the main shaft 5 can be driven by a motor. One end of the main shaft 5 located inside the pump body 1 is eccentrically connected to a swashplate 6, one end of which slides with the closed end of the pump body 1 and the other end is inclined. The side of the swashplate 6 closest to the main shaft 5 is a small head, and the other side is a large head. The outer circle of the large head of the swashplate 6 is provided with a balance groove 9 that makes the center of mass of the swashplate 6 coincide with the axis of the main shaft 5. That is, the main shaft 5 can drive the swashplate 6 to rotate, and the center of mass of the swashplate 6 coincides with the axis of the main shaft 5, reducing the centrifugal force of the swashplate 6 rotation. The inner side of the end cover 2 is provided with an annular boss that is movably fitted with the main shaft 5. Between the annular boss and the swashplate 6, there is an upper sliding plate 7 that is movably fitted with the main shaft 5 on the same axis. One end of the upper sliding plate 7 is universally fitted with the annular boss, and the other end is slidably fitted with the inclined end of the swashplate 6. That is, during the rotation of the swashplate 6, it can push the upper sliding plate 7 to swing in space, while ensuring that the upper sliding plate 7 does not interfere with the main shaft 5 during the swing.

[0036] Multiple plunger assemblies are arranged circumferentially between the upper sliding plate 7 and the end cover 2. Each plunger assembly includes a plunger tube 8 with open ends. Ball sleeves 10 are movable at both ends of the plunger tube 8. The two ball sleeves 10 are universally connected to the upper sliding plate 7 and the end cover 2, respectively. This allows the plunger tube 8 to move freely between the two ball sleeves 10 as the sliding plate 7 swings. Compared to existing structures, this design balances the pressure on both sides of the plunger tube 8, eliminating lateral forces and preventing excessive axial velocity and acceleration in the plunger tube 8 under high-speed conditions, thus improving stability. If necessary, a lower sliding plate 18 is provided at the end of the upper sliding plate 7 opposite to the swashplate 6. A pressure plate 19 is provided on the inner side of the end cover 2, coaxially fitted with the annular boss of the end cover 2. Corresponding ball sleeves 10 are provided between the lower sliding plate 18 and the upper sliding plate 7, and between the pressure plate 19 and the end cover 2, corresponding to the positions of the plunger assemblies. The upper slide plate 7 corresponds to the universal joint spherical cavity, which has a simple structure and is easy to assemble. The lower slide plate 18 and the annular boss of the end cover 2 are universally connected through the supporting ball joint 20. The supporting ball joint 20 is movably sleeved with the main shaft 5 and is correspondingly and tightly connected to the annular boss of the end cover 2, which effectively improves the stability of the upper slide plate 7 and the lower slide plate 18. A limiting mechanism 14 is provided between one side of the upper slide plate 7 and the pump body 1 to prevent the upper slide plate 7 from rotating. As needed, the limiting mechanism 14 includes a limiting pin provided on the inner wall of the pump body 1, and the upper slide plate 7 is provided with a sliding groove that slides with the limiting pin; or the limiting pin is provided on the upper slide plate 7, and the inner wall of the pump body 1 is provided with a sliding groove that slides with the limiting pin. That is, the axial rotation of the upper slide plate 7 is limited by the cooperation of the limiting pin and the sliding groove, while the limiting pin can slide along the sliding groove without affecting the spatial swing of the upper slide plate 7.

[0037] The upper sliding plate 7 has oil passage holes 11 at the corresponding positions of the plunger assembly, which can be covered by the large head of the swash plate 6 and exposed on the outside of the small head of the swash plate 6. The oil passage holes 11 are connected to the plunger tube 8. The large head of the inclined end of the swash plate 6 has a high-pressure oil chamber 12 that can communicate with the oil passage holes 11. The other end has an 8-shaped oil discharge chamber 13. One circular cavity of the oil discharge chamber 13 is connected to the high-pressure oil chamber 12, and the other circular cavity is coaxial with the main shaft 5 and connected to the oil outlet 4. That is, the oil passage holes 11 and the plunger tube are connected to the plunger tube. The volume of the cavity between 8 changes with the swing of the upper sliding plate 7. As the oil passage 11 is exposed to the large head of the upper sliding plate 7, the volume of the cavity decreases, thereby pressing the liquid in the cavity into the high-pressure oil chamber 12, and then into the oil discharge chamber 13, and discharged through the oil outlet 4 to achieve the purpose of oil discharge. As the swashplate 6 continues to rotate, as the oil passage 11 is exposed from the large head of the upper sliding plate 7, the volume of the cavity increases, and the liquid in the pump body 1 can enter the cavity between the oil passage 11 and the plunger tube 8 to achieve the purpose of oil suction.

[0038] During operation, the oil inlet 3 is connected to the liquid storage tank, allowing liquid to enter the pump body 1 through the oil inlet 3. The motor drives the main shaft 5, which in turn drives the swashplate 6 to rotate. During the rotation of the swashplate 6, the upper sliding plate 7 can swing in space. The volume of the cavity between the oil passage 11 and the plunger tube 8 changes with the swing of the upper sliding plate 7. As the oil passage 11 is exposed to the large head of the upper sliding plate 7, the volume of the cavity decreases, thereby pressurizing the liquid in the cavity into the high-pressure oil chamber 12, and then into the oil discharge chamber 13, and is discharged through the oil outlet 4, achieving the purpose of oil discharge. As the swashplate 6 continues to rotate, as the oil passage 11 is exposed from the large head of the upper sliding plate 7, the volume of the cavity increases, and the liquid in the pump body 1 can enter the cavity between the oil passage 11 and the plunger tube 8, achieving the purpose of oil suction.

[0039] Example 2:

[0040] Combined with appendix Figures 1-5 A force-balanced swashplate plunger pump differs from Embodiment 1 in that, based on Embodiment 1, the high-pressure oil chamber 12 is an arc-shaped cavity structure with its center coinciding with the axis of the main shaft 5. This facilitates the entry of liquid from the cavity between the oil passage 11 and the plunger tube 8 into the high-pressure oil chamber 12, thus avoiding obstruction to the swing of the upper sliding plate 7.

[0041] Example 3:

[0042] Combined with appendix Figures 1-5 A force-balanced swashplate plunger pump, based on Embodiment 1 or 2, has a wear-resistant disc 15 slidably fitted to a swashplate 6 at the closed end of the pump body 1, with a pin 16 between the wear-resistant disc 15 and the closed end of the pump body 1. A ring sleeve, coaxially and tightly inserted with the oil outlet 4, is provided on the wear-resistant disc 15 at the position corresponding to the oil outlet 4. The wear-resistant disc 15 has good wear resistance, effectively improving its service life. The oil outlet 4 is coaxial with the main shaft 5. The swashplate 6 has an oil drain pipe 24 rotatably connected to the ring sleeve of the wear-resistant disc 15, and the oil drain pipe 24 is connected to the oil drain chamber 13, effectively improving the stability of the swashplate 6. A copper sleeve 17 is provided between the oil drain pipe 24 and the ring sleeve of the wear-resistant disc 15, effectively reducing the friction between the oil drain pipe 24 and the wear-resistant disc 15. Reinforcing ribs are provided inside the oil drain pipe 24, effectively improving its structural strength.

[0043] Example 4:

[0044] Combined with appendix Figures 1-5 A force-balanced swashplate plunger pump, based on any one of the embodiments in Examples 1 to 3, wherein a sealing ring 21 is provided between the pump body 1 and the end cover 2, and an oil seal 22 is provided between the main shaft 5 and the end cover 2, effectively improving the overall sealing performance; the main shaft 5 and the end cover 2 are rotatably connected by a bearing 23, effectively improving the stability of the rotation of the main shaft 5.

[0045] The parts of this invention not described in detail are prior art. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and are intended to encompass all changes falling within the meaning and scope of equivalents within this invention.

Claims

1. A force-balanced swashplate plunger pump, comprising a hollow pump body (1) with one open end, an end cap (2) installed on the open end of the pump body (1), and an oil inlet (3) and an oil outlet (4) spaced apart and communicating with its internal cavity at the closed end; characterized in that: The end cap (2) is rotatably connected to a main shaft (5) with one end extending into the inner cavity of the pump body (1). The main shaft (5) is located inside the pump body (1) and is eccentrically connected to a swashplate (6) with one end slidingly engaged with the closed end of the pump body (1) and the other end inclined. The swashplate (6) has a small head on the side near the main shaft (5) and a large head on the other side. The outer circle of the large head of the swashplate (6) is provided with a balance groove (9) that makes the center of mass of the swashplate (6) coincide with the axis of the main shaft (5). The inner side of the end cap (2) is provided with an annular boss that is movably fitted with the main shaft (5). Between the annular boss and the swashplate (6) is an upper sliding plate (7) that is movably fitted with the main shaft (5) on the same axis. One end of the upper sliding plate (7) is universally engaged with the annular boss, and the other end is slidably engaged with the inclined end of the swashplate (6). Multiple plunger assemblies are arranged circumferentially between the upper sliding plate (7) and the end cover (2). Each plunger assembly includes a plunger tube (8) with open ends. Both ends of the plunger tube (8) are equipped with ball sleeves (10). The two ball sleeves (10) are universally connected to the upper sliding plate (7) and the end cover (2), respectively. A limiting mechanism (14) to prevent the upper sliding plate (7) from rotating is provided between one side of the upper sliding plate (7) and the pump body (1). The upper sliding plate (7) is provided with oil passage holes (11) at the positions corresponding to the plunger assemblies. These holes can be covered by the large head of the swash plate (6) and exposed on the outside of the small head of the swash plate (6). The oil passage holes (11) are connected to the plunger tubes (8). The inclined end of the swash plate (6) is provided with a high-pressure oil chamber (12) that can communicate with the oil passage (11), and the other end is provided with an oil discharge chamber (13) in the shape of an 8. One circular cavity of the oil discharge chamber (13) is connected to the high-pressure oil chamber (12), and the other circular cavity is coaxial with the main shaft (5) and connected to the oil outlet (4).

2. The plunger pump with force-balanced swashplate flow distribution as described in claim 1, characterized in that: The high-pressure oil chamber (12) is an arc-shaped cavity structure whose center coincides with the axis of the main shaft (5).

3. The plunger pump with force-balanced swashplate flow distribution as described in claim 1, characterized in that: The pump body (1) is provided with a wear-resistant disc (15) that slides with the swashplate (6) at the closed end, and a pin (16) is provided between the wear-resistant disc (15) and the closed end of the pump body (1). The wear-resistant disc (15) is provided with a ring sleeve that is coaxially and tightly inserted with the oil outlet (4) at the position corresponding to the oil outlet (4).

4. The plunger pump with force-balanced swashplate flow distribution as described in claim 3, characterized in that: The oil outlet (4) is coaxial with the main shaft (5), and the swash plate (6) is provided with an oil drain pipe (24) that is coaxially and rotatably connected to the wear-resistant disc (15) ring sleeve, and the oil drain pipe (24) is connected to the oil drain chamber (13).

5. The plunger pump with force-balanced swashplate distribution as described in claim 4, characterized in that: A copper sleeve (17) is provided between the oil drain pipe (24) and the wear-resistant disc (15) ring, and a reinforcing rib is provided inside the oil drain pipe (24).

6. The plunger pump with force-balanced swashplate distribution as described in claim 1, characterized in that: The upper sliding plate (7) is provided with a lower sliding plate (18) at one end away from the swashplate (6). The end cover (2) is provided with a pressure plate (19) coaxially sleeved with the annular boss of the end cover (2). The lower sliding plate (18) and the upper sliding plate (7) and the pressure plate (19) and the end cover (2) are provided with spherical cavities that are universally matched with the corresponding ball sleeves (10) at the positions of the plunger assemblies.

7. The plunger pump with force-balanced swashplate distribution as described in claim 6, characterized in that: The sliding plate (18) and the annular boss of the end cover (2) are connected in a universal joint via a supporting ball joint (20). The supporting ball joint (20) is movably sleeved with the main shaft (5) and is correspondingly and tightly connected to the annular boss of the end cover (2).

8. The plunger pump with force-balanced swashplate flow distribution as described in claim 1, characterized in that: The limiting mechanism (14) includes a limiting pin provided on the inner wall of the pump body (1), and the upper slide plate (7) is provided with a sliding groove that slides with the limiting pin; or the limiting pin is provided on the upper slide plate (7), and the inner wall of the pump body (1) is provided with a sliding groove that slides with the limiting pin.

9. The plunger pump with force-balanced swashplate distribution as described in claim 1, characterized in that: A sealing ring (21) is provided between the pump body (1) and the end cover (2), and an oil seal (22) is provided between the main shaft (5) and the end cover (2).

10. The plunger pump with force-balanced swashplate flow distribution as described in claim 1, characterized in that: The main shaft (5) and the end cover (2) are rotatably connected by a bearing (23).

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