A return disc for a small displacement high-speed axial plunger pump

Abstract

The utility model provides a kind of backstroke disc for small-displacement high-speed axial plunger pump, including backstroke disc;The backstroke disc includes disc main body, and multiple slide shoe mounting holes are uniformly distributed along disc main body axis circumference, and boss is coaxially arranged in disc main body;The boss is equipped with middle hole, and ball hinge is assembled in middle hole;The inner wall of middle hole is constituted by taper face, spherical surface, transition circular arc, taper face is located at the entry side of middle hole, and spherical surface is located at the bottom side of middle hole;Taper face and spherical surface are smoothly connected by tangent point b, and the end of spherical surface is transitioned to the right end surface of disc main body of disc main body by transition circular arc;The material of backstroke disc is high-speed steel, and is quenched heat treated.The utility model taper face and the frictional contact of spherical surface of ball hinge are line contact, and the contact area of line contact is smaller, when backstroke disc and ball hinge rub, ball hinge spherical surface is not easy to cause burn and adhesion, and maintain the original structural strength of middle hole and boss part;On the other hand, the material of backstroke disc uses high-speed steel, and heat treatment mode is quenching, compared with nitriding treatment of nitriding steel, heat treatment deformation is small, processing difficulty is small after heat treatment, and the qualified rate is higher.

Description

Technical Field

[0001] This utility model relates to a return plate for a small-displacement high-speed axial piston pump, belonging to the technical field of hydraulic piston pumps, specifically to a small-displacement high-speed axial piston pump with a return plate having a conical surface plus a spherical arc surface structure in the central hole. Background Technology

[0002] Axial piston pumps, as power components in hydraulic systems, offer advantages such as a high power-to-weight ratio, high volumetric efficiency, and long service life, making them suitable for applications in aerospace, robotics, and EHA (Environmentally Harmonious Automation). Due to limitations in installation space and weight, axial piston pumps are evolving towards miniaturization, higher speed, higher pressure, and higher power-to-weight ratio. To reduce structural size and weight while meeting flow requirements, smaller displacement and higher speed designs are typically employed. This necessitates the rational design of the structural dimensions of the minute rotating parts within the small displacement, high-speed axial piston pump, especially the design of the return plate.

[0003] The return disc rotates at high speed along with the drive shaft, driven by the plunger. There is relative motion between the return disc and the ball joint, forming a friction pair. To address wear caused by friction, the existing method involves using a spherical structure in the center hole of the return disc to mate with the spherical surface of the ball joint. The return disc and ball joint must be lapped together before being stored as a set. The return disc is made of nitrided steel and undergoes nitriding heat treatment. However, this method has only been validated in axial piston pumps with a displacement greater than 10 mL / r and a rated speed less than 3000 rpm. When the spherical structure is used in pumps with a displacement less than 1... When operating a high-speed axial piston pump with a displacement of 0 mL / r, the rated speed of the pump exceeds 3000 rpm, even reaching over 10000 rpm. The spherical joint design has the disadvantage of a large contact area, which can easily lead to burns on the mating spherical surfaces due to the high temperatures generated by friction at high speeds. This can even cause the return disc to stick to the ball joint. Furthermore, since the minimum wall thickness of the spherical portion in small-displacement axial piston pumps is less than 1.2 mm, significant deformation occurs during nitriding, increasing processing difficulty, resulting in a low yield rate, and even scrapping the entire pump. Therefore, existing technologies suffer from problems such as adhesion between the return disc and the ball joint, significant deformation during heat treatment, increased processing difficulty, and a low yield rate. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a return disc for a small displacement high-speed axial piston pump.

[0005] This utility model is achieved through the following technical solution.

[0006] This utility model provides a return plate for a small-displacement high-speed axial piston pump, comprising a return plate; the return plate includes a disc body, with multiple sliding shoe mounting holes evenly distributed circumferentially along the axis of the disc body, and a boss coaxially arranged inside the disc body; the boss has a central hole, and a ball joint is assembled inside the central hole; the inner wall of the central hole is composed of a conical surface, a spherical arc surface, and a transition arc, with the conical surface located on the inlet side of the central hole and the spherical arc surface located on the bottom side of the central hole; the conical surface and the spherical arc surface are smoothly connected through a tangent point b, and the end of the spherical arc surface transitions to the right end face of the disc body through a transition arc; the return plate is made of high-speed steel and has undergone quenching heat treatment.

[0007] The central hole penetrates the boss.

[0008] The cone angle of the cone surface is α, and it forms line contact friction with the spherical surface of the ball joint.

[0009] The diameter of the spherical arc surface is larger than the diameter of the spherical hinge surface, thus creating a non-contact gap between the spherical arc surface and the spherical hinge.

[0010] The conical surface is tangent to a virtual measuring sphere at point a. The diameter of the measuring sphere is equal to the diameter of the spherical hinge surface, and the tangency point a is located in the middle of the conical surface.

[0011] The minimum wall thickness H2 of the virtual extension surface of the spherical arc surface and the sliding shoe mounting hole is greater than the minimum wall thickness H1 of the virtual extension surface of the conical surface and the sliding shoe mounting hole.

[0012] The tangent point b is located at the junction of the end of the cone and the spherical arc surface.

[0013] The beneficial effects of this utility model are as follows: the frictional contact between the conical surface and the spherical surface of the ball joint is a line contact, and the contact area of ​​the line contact is small. When the return plate rubs against the ball joint, it is not easy to cause the spherical surface of the ball joint to be burned or stuck, and the original structural strength of the central hole and the boss is maintained. On the other hand, the material of the return plate is high-speed steel, and the heat treatment method is quenching. Compared with the nitriding treatment of nitriding steel, the heat treatment deformation is small, the processing difficulty after heat treatment is small, and the pass rate is high. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 yes Figure 1 Side view; Figure 3 yes Figure 2 Enlarged view of section I; Figure 4 yes Figure 2 Enlarged view of section II; Figure 5 This is an assembly drawing of this utility model; In the diagram: 1-Return plate, 2-Spherical hinge, 3-Spherical hinge spherical surface, 4-Disc body, 5-Slipper mounting hole, 6-Boss, 7-Center hole, 8-Conical surface, 9-Spherical arc surface, 10-Transition arc, 11-Measuring ball, 12-Virtual extension surface of spherical arc surface, 13-Virtual extension surface of conical surface, 14-Right end face of disk body, 15-Slipper contact surface. Detailed Implementation

[0015] The technical solution of this utility model is further described below, but the scope of protection is not limited to what is described.

[0016] like Figures 1-5 As shown, it includes a disc body 4, a sliding shoe mounting hole 5, a boss 6, and a central hole 7. The boss 6 and the central hole 7 are coaxial with the disc body 4. The sliding shoe mounting hole 5 is evenly distributed around the axis of the disc body 4. The central hole 7 passes through the entire boss 6 and is used to support the ball joint 2.

[0017] Furthermore, the central hole 7 is provided with a conical surface 8, a spherical arc surface 9, and a transition arc 10. The conical surface 8 is tangent to the measuring ball 11 at the tangency point a, which is located in the middle of the conical surface 8. The cone angle of the conical surface 8 is α. The conical surface 8 is tangent to the spherical arc surface 9 at the tangency point b, which is located at the connection point between the end of the conical surface 8 and the spherical arc surface 9. The transition arc 10 connects the spherical arc surface 9 and the right end face 14 of the disk body.

[0018] Furthermore, the diameter Sφd1 of the measuring ball 11 tangent to the conical surface 8 is the same as the diameter of the ball joint spherical surface 3 of the ball joint 2, and the frictional contact between the conical surface 8 and the ball joint spherical surface 3 is a line contact. Compared with the contact between spherical surfaces, the contact area of ​​the line contact is smaller, and when the return plate 1 rubs against the ball joint 2, it is less likely to cause the ball joint spherical surface 3 to be burned, and it is less likely to cause the two to stick together.

[0019] Furthermore, the diameter Sφd2 of the spherical arc surface 9 is greater than the diameter Sφd1 of the measuring ball 11, and the diameter of the spherical arc surface 9 is greater than the diameter of the spherical surface of the ball hinge 3. Therefore, the spherical arc surface 9 and the ball hinge 3 do not contact each other, and the spherical arc surface 9 is not a mating surface. The return plate 1 and the ball hinge 2 do not need to be lapped and put into storage as a set, and the processing accuracy requirements are greatly reduced.

[0020] Specifically, the function of the spherical arc surface 9 is to prevent the opening diameter of the cone surface 8 on the right end face 14 of the disk body from being too large when there is only the cone surface 8, which would lead to a reduction in wall thickness. Therefore, compared with the cone surface 8 alone, it enhances the structural strength and maintains the original structural strength of the central hole 7 and the boss 6.

[0021] Preferably, the wall thickness H1 of the virtual extension surface 13 of the conical surface 8 and the sliding shoe mounting hole 5 is less than the wall thickness H2 of the virtual extension surface 12 of the spherical surface and the sliding shoe mounting hole 5.

[0022] Preferably, the return plate 1 is made of high-speed steel and the heat treatment method is quenching. The advantages are that the heat treatment deformation is small, the processing difficulty after heat treatment is small, and the pass rate is high.

[0023] Specifically, high-speed steel can solve the problem that the minimum wall thickness is within 1.2m, which causes large deformation during heat treatment, leading to increased processing difficulty and a low pass rate after heat treatment.

[0024] Furthermore, by setting the conical surface 8 and the spherical arc surface 9, the problem of the spherical surfaces of the return plate 1 and the ball joint 2 being burned due to the large contact area of ​​their mating surfaces is solved, and even the return plate 1 and the ball joint 2 are stuck together. At the same time, the original structural strength of the central hole 7 and the boss 6 is maintained.

[0025] In summary, the structure combining a conical surface and a spherical arc surface ensures that the frictional contact between the conical surface and the spherical surface of the ball joint is a line contact, which reduces the risk of burning and adhesion of the spherical surface. The return plate and the ball joint do not require mating or assembly into a single unit. Furthermore, the spherical arc surface prevents the opening diameter of the conical surface from being too large, which would reduce the wall thickness, thus enhancing structural strength. Additionally, the high-speed steel exhibits minimal heat treatment deformation after quenching, resulting in easier post-heat treatment machining and a higher pass rate. This addresses the problem of significant heat treatment deformation due to minimum wall thicknesses being less than 1.2m, which leads to increased machining difficulty and a lower pass rate after heat treatment.

Claims

1. A return disc for a small displacement high-speed axial piston pump, comprising a return disc (1), characterized in that: The return disk (1) includes a disk body (4), with multiple sliding shoe mounting holes (5) evenly distributed circumferentially along the axis of the disk body (4), and a boss (6) coaxially arranged inside the disk body (4); the boss (6) has a central hole (7), and a ball joint (2) is assembled inside the central hole (7); the inner wall of the central hole (7) is composed of a conical surface (8), a spherical arc surface (9), and a transition arc (10), with the conical surface (8) located on the entrance side of the central hole (7) and the spherical arc surface (9) located on the bottom side of the central hole (7); the conical surface (8) and the spherical arc surface (9) are smoothly connected through the tangent point b, and the end of the spherical arc surface (9) transitions to the right end face (14) of the disk body (4) through the transition arc (10); the material of the return disk (1) is high-speed steel and has undergone quenching heat treatment.

2. The return disc for a small-displacement high-speed axial piston pump as described in claim 1, characterized in that: The central hole (7) passes through the boss (6).

3. The return disc for a small-displacement high-speed axial piston pump as described in claim 1, characterized in that: The cone angle of the cone surface (8) is α, and it forms line contact friction with the ball joint surface (3) of the ball joint (2).

4. The return disc for a small-displacement high-speed axial piston pump as described in claim 1, characterized in that: The diameter of the spherical arc surface (9) is larger than the diameter of the spherical hinge surface (3), so that a non-contact gap is formed between the spherical arc surface (9) and the spherical hinge (2).

5. The return disc for a small-displacement high-speed axial piston pump as described in claim 1, characterized in that: The cone surface (8) is tangent to a virtual measuring sphere (11) at point a. The diameter of the measuring sphere (11) is equal to the diameter of the spherical hinge surface (3). The tangent point a is located in the middle of the cone surface (8).

6. The return disc for a small-displacement high-speed axial piston pump as described in claim 1, characterized in that: The minimum wall thickness H2 of the spherical arc virtual extension surface (12) of the spherical arc surface (9) and the sliding shoe mounting hole (5) is greater than the minimum wall thickness H1 of the conical arc virtual extension surface (13) of the conical surface (8) and the sliding shoe mounting hole (5).

7. The return disc for a small-displacement high-speed axial piston pump as described in claim 1, characterized in that: The tangent point b is located at the junction of the end of the conical surface (8) and the spherical surface (9).

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