Variable backhaul apparatus

Abstract

This utility model relates to a variable return device, specifically in the field of closed-loop hydraulic piston pump technology. A drive shaft passes through the central axis of the piston cylinder. Multiple inner cavities are evenly distributed around the drive shaft in the piston cylinder's circumference. A piston is housed within each cavity, with one end serving as a load oil pressure inlet. A slipper is connected to the end of the piston cylinder furthest from the load oil pressure inlet. A ball joint is integrally formed with the piston cylinder. A return disc is fitted around the outer side of the ball joint. Multiple slipper holes are evenly distributed around the return disc's circumference, with slippers inserted into these holes. A notch is provided on the edge of the return disc, communicating with the slipper holes. The cylinder body and ball joint are designed as a single unit, resulting in a simple structure. The integrated piston cylinder offers good manufacturability, reducing manufacturing costs. The notch-type return disc allows for easy insertion from the narrow neck of the piston during installation, reducing the volume of the return disc and thus the overall size of the piston pump.

Description

Technical Field

[0001] This utility model relates to the application of closed-loop hydraulic piston pump technology, and in particular to a variable return device. Background Technology

[0002] like Figure 1 , 2 As shown, in the axial piston pump, the piston cylinder 6, ball joint 61, and return disk 5 constitute a variable return mechanism. The drive shaft transmits power to the piston cylinder 6 and ball joint 61 via a spline. The piston cylinder 6 and ball joint 61 are two separate parts. The return disk 5 has a circular design for mounting the slipper hole. The central conical surface of the return disk 5 slides on the arc surface of the ball joint 61 to achieve variable displacement. Under no load or low load conditions, an oil film cannot be established on the surface of the slipper 2 to achieve hydrostatic balance. Therefore, to prevent leakage on the surface of the slipper 2 under low load conditions, the spring force is transmitted to the ejector pin 7 by compressing the central spring 12 and setting a reasonable compression amount. The ejector pin 7 acts on the end face of the ball joint 61, and the spherical surface of the ball joint 61 is squeezed against the central conical surface of the return disk 5, pressing the end face of the return disk 5 against the end face of the slipper 2. This creates a certain surface pressure between the lower end face of the slipper 2 and the contact surface of the sliding disk 4, achieving sealing of the end face of the slipper 2 under low load conditions. When the load pressure is established, the preload of the central spring 12 is negligible compared to the hydraulic pressure. In the oil discharge zone, the slipper 2 can still form hydrostatic support, causing it to "float" and form an oil film of a certain thickness, sealing the end face of the slipper 2. In the oil suction zone, the preload of the central spring 12 overcomes the inertial force of the plunger 3's axial movement, friction, and the sum of the hydraulic pressure formed by the pressure difference between the housing cavity and the oil suction cavity, still pressing the slipper 2 against the slide plate, preventing the slipper 2 from detaching from the slide plate end face and causing "slipper lifting" in the low-pressure zone. Once "slipper lifting" occurs in the low-pressure oil suction zone, the slipper 2 will instantly slam against the surface of the slide plate 4 when it rotates to the high-pressure zone, causing damage to the slipper 2.

[0003] This variable return mechanism design achieves sealing of the slipper 2 end face and good return characteristics of the plunger 3 in the low-pressure suction zone. In the high-pressure discharge zone, the reasonable design of the central spring 12 force does not affect the formation of the hydrostatic support sealing oil film on the slipper 2 end face. However, this structure is relatively complex and has high manufacturing costs when applied to an axially closed plunger pump. Secondly, the return disc 5 has a perfectly circular design for the slipper mounting hole 52, resulting in a large volume of the return disc 5. This makes the variable return mechanism and the entire closed plunger pump too large and not compact enough, especially in miniature equipment with strict space requirements, where it has no advantage.

[0004] Therefore, in axially closed piston pump applications, it is essential to develop and design a compact and low-cost variable return mechanism that ensures good sealing performance of the slipper 2 end face in the low-pressure suction zone and good return characteristics of the plunger 3. Furthermore, it should not affect the formation of the hydrostatic support sealing oil film on the slipper 2 end face in the high-pressure discharge zone. Utility Model Content

[0005] For axial piston pumps used in open systems, the variable return mechanism is structurally complex and has high manufacturing costs when applied to axial closed piston pumps. Furthermore, the circular hole structure design of the return disc results in a large piston pump size, which limits its application in miniature equipment. Therefore, a variable return device is proposed.

[0006] The technical solution of this utility model is as follows: a variable return device, including a plunger cylinder, a transmission shaft passing through the central axis of the plunger cylinder, a plurality of inner cavities uniformly arranged around the circumference of the plunger cylinder around the transmission shaft, a plunger being provided inside the inner cavity, one end of the inner cavity being a load oil pressure inlet, and the end of the plunger away from the load oil pressure inlet being connected to a slipper. The piston cylinder is provided with a ball joint at the end away from the load oil pressure inlet, and the ball joint is integrally formed with the piston cylinder. The ball joint is fitted with a return plate on its outer side. The return plate has a plurality of uniformly arranged slipper holes along its circumferential axis. The slipper is inserted into the slipper holes. The edge of the return plate has a notch that is connected to the slipper holes.

[0007] Preferably, the edge of the center hole of the return plate is a conical surface, and the conical surface matches the shape of the outer surface of the ball joint.

[0008] Preferably, one end of the plunger is spherical, and the slipper has a spherical groove on the side near the plunger, with the plunger connected to the spherical groove of the slipper through the spherical end.

[0009] Preferably, a sliding plate is provided on the side of the slipper away from the plunger, and the sliding plate is sleeved on the outside of the drive shaft.

[0010] The advantages of this invention are as follows: The cylinder body and ball joint of this plunger cylinder are designed as a single unit, eliminating the need for the ejector pin, central spring, and washer in the variable return mechanism, resulting in a simpler structure. Secondly, the one-piece plunger cylinder offers good machinability, allowing for one-time clamping and turning, thus reducing manufacturing costs. The return disc mounting shoe hole adopts a notch design, allowing for easy insertion from the narrow neck of the plunger during installation, effectively reducing the volume of the return disc and consequently minimizing the overall size of the plunger pump. Attached Figure Description

[0011] Figure 1 A cross-sectional view of an existing variable return device; Figure 2 This is a schematic diagram of the existing return stack structure; Figure 3 This is a cross-sectional view of the variable return device of this utility model; Figure 4 This is a perspective view of the plunger cylinder of this utility model; Figure 5 This is a perspective view of the return plate of this utility model.

[0012] The component names corresponding to the various reference numerals in the diagram are as follows: 1. Drive shaft; 11. Washer; 12. Center spring; 2. Slipper; 3. Piston; 4. Sliding plate; 5. Return plate; 51. Conical surface; 52. Slipper hole; 53. Notch; 6. Piston cylinder; 61. Ball joint; 62. Inner cavity; 63. Load oil pressure inlet; 7. Ejector pin. Detailed Implementation

[0013] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. This embodiment is based on the technical solution of the present invention and provides detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0014] refer to Figure 3 , 4 As shown in the embodiment of this application, a variable return device is disclosed, including a plunger cylinder 6. A transmission shaft 1 passes through the central axis of the plunger cylinder 6. The plunger cylinder 6 is uniformly provided with a plurality of inner cavities 62 around the transmission shaft 1. A plunger 3 is provided inside the inner cavity 62. One end of the inner cavity 62 is a load oil pressure inlet 63. The end of the plunger 3 away from the load oil pressure inlet 63 is connected to a slipper 2. One end of the plunger 3 is spherical, and the slipper 2 has a spherical groove on the side near the plunger 3. The plunger 3 is connected to the spherical groove of the slipper 2 through the spherical end. The side of the slipper 2 away from the plunger 3 is provided with a sliding plate 4, which is sleeved on the outside of the drive shaft 1. The plunger cylinder 6 is provided with a ball joint 61 at the end away from the load oil pressure inlet 63, and the ball joint 61 is integrally formed with the plunger cylinder 6. refer to Figure 3 , 5 As shown, a return plate 5 is sleeved on the outer side of the ball joint 61. The return plate 5 has a plurality of uniformly arranged slipper holes 52 along the circumferential axis. The slipper 2 passes through the slipper hole 52. The edge of the return plate 5 has a notch 53, which is connected to the slipper hole 52. The notch 53 is used to facilitate the plunger 3 to be pushed into the slipper hole 52 at the minimum diameter of the neck. The edge of the central hole of the return plate 5 is a conical surface 51, and the conical surface 51 matches the shape of the outer surface of the ball joint 61; The specific working principle is as follows: Compared to open systems, closed systems, due to the presence of the make-up pump, have a make-up oil pressure of approximately 25 bar on the low-pressure side. When the plunger 3 and slipper 2 rotate to the low-pressure suction zone, the make-up oil pressure on the low-pressure side presses the slipper 2 tightly against the surface of the slide plate 4, achieving a pre-pressure seal. The central spring 12 is no longer needed to provide pre-tightening force to create surface pressure between the slipper 2 and the slide plate 4. Therefore, the ball joint 61 and the cylinder body of the plunger cylinder 6 can be designed as a single unit, eliminating the need for the ejector pin 7, central spring 12, and washer 11. Costs are reduced through process optimization and fewer parts. When the plunger 3 and slipper 2 rotate to the high-pressure discharge zone, the mechanism of hydrostatic support between the slipper 2 and the slide plate 4 remains unaffected.

[0015] In a closed-loop system, the return plate 5 can theoretically be eliminated due to the presence of replenishing oil pressure. The inertial force and frictional resistance experienced by the plunger 3 in the low-pressure suction zone are overcome by the hydraulic pressure generated by the replenishing oil pressure, pushing the slipper 2 towards the surface of the sliding plate 4. Since the high-speed rotation of the slipper 2 generates centrifugal force, making it prone to tipping over, the primary function of the return plate 5 in a closed-loop pump is to prevent the slipper 2 from tipping over. The return plate 5 features a slipper mounting hole 52 with a notch 53. During installation, the slipper 2 only needs to be pushed in from the smallest diameter point of the plunger 3's neck. The slipper hole 52 of the return plate 5 does not need to be larger than the diameter of the plunger 3. This design effectively reduces the volume of the return plate 5, thereby reducing the overall size of the plunger pump. When installing the slipper 2 on the traditional return plate 5, since the plunger 3 and slipper 2 are integrally pressed structures, the diameter of the mounting hole of the return plate 5 must be larger than the diameter hole of the plunger 3 in order to achieve installation. This requires a large pitch circle diameter of the mounting hole 52 of the return plate 5, which in turn increases the overall volume of the return plate 5, resulting in a non-compact structure of the variable return mechanism and assembly, and limiting the application space.

[0016] The beneficial effects are: The piston cylinder 6 of this utility model features an integrated structure where the cylinder body and ball joint 61 are one piece, eliminating the need for the ejector pin 7, central spring 12, and washer 11 in the variable return mechanism, resulting in a simpler structure. Furthermore, the integrated piston cylinder 6 offers superior machining capabilities, allowing for one-time clamping and turning, thus reducing manufacturing costs. The return disc 5's mounting shoe hole 52 employs a notch 53 design, allowing for easy insertion from the narrow neck of the piston 3, effectively reducing the volume of the return disc 5 and consequently minimizing the overall size of the piston pump.

[0017] It should be noted that the terms "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. "A plurality of" means two or more. "Installed," "connected," and "joined" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection.

[0018] The above description is merely a preferred embodiment of this utility model and is not intended to limit this utility model in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from this utility model, and these improvements and additions should also be considered within the protection scope of this utility model. Any modifications, alterations, and equivalent changes made by those skilled in the art without departing from the spirit and scope of this utility model using the disclosed technical content are equivalent embodiments of this utility model. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of this utility model are still within the scope of the technical solution of this utility model.

Claims

1. A variable back lash device characterized by, Includes a plunger cylinder (6), a drive shaft (1) passes through the central axis of the plunger cylinder (6), and the plunger cylinder (6) is evenly provided with multiple inner cavities (62) around the drive shaft (1) in the circumference. A plunger (3) is provided inside the inner cavity (62), one end of the inner cavity (62) is a load oil pressure inlet (63), and the end of the plunger (3) away from the load oil pressure inlet (63) is connected to a slipper (2). The plunger cylinder (6) has a ball joint (61) at one end away from the load oil pressure inlet (63), and the ball joint (61) is integrally formed with the plunger cylinder (6); The ball joint (61) is fitted with a return plate (5) on its outer side. The return plate (5) is provided with a plurality of uniformly arranged slipper holes (52) along the circumferential direction of the axis. The slipper (2) is inserted into the slipper hole (52). The edge of the return plate (5) is provided with a notch (53), which is connected to the slipper hole (52).

2. The variable backhaul apparatus of claim 1, wherein The edge of the central hole of the return plate (5) is a conical surface (51), which matches the shape of the outer surface of the ball joint (61).

3. The variable backhaul apparatus of claim 1, wherein One end of the plunger (3) is spherical, and the slipper (2) has a spherical groove on the side near the plunger (3). The plunger (3) is connected to the spherical groove of the slipper (2) through the spherical end.

4. The variable return device according to claim 1, characterized in that, The slipper (2) is provided with a slide plate (4) on the side away from the plunger (3), and the slide plate (4) is sleeved on the outside of the drive shaft (1).

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