CN217354620U

CN217354620U - Axial plunger pump

Info

Publication number: CN217354620U
Application number: CN202221016610.7U
Authority: CN
Inventors: 李彬
Original assignee: Bosch Rexroth Beijing Hydraulic Co Ltd
Current assignee: Bosch Rexroth Beijing Hydraulic Co Ltd
Priority date: 2022-04-28
Filing date: 2022-04-28
Publication date: 2022-09-02
Anticipated expiration: 2032-04-28

Abstract

An axial plunger pump comprising: a pump housing formed of a housing body and a rear cover, the housing body having an end wall and a peripheral wall extending forwardly from the end wall; a drive shaft carried by the pump housing; a cylinder block provided in the pump housing, the cylinder block being rotatably driven by the drive shaft, the cylinder block having a plurality of plunger chambers formed therein, one plunger being slidably inserted in each plunger chamber; the cylinder body is provided with an oil port which radially extends to the periphery of the cylinder body from the front end of each plunger cavity; the axial plunger pump further comprises a flow distribution ring which is fixed in the peripheral wall and surrounds the periphery of the cylinder body to form a sliding bearing for supporting the cylinder body to rotate, and the flow distribution ring is provided with an oil discharge groove and an oil suction groove at axial positions corresponding to the oil ports. The maximum allowable speed of the pump can be increased.

Description

Axial plunger pump

Technical Field

The present application relates to an axial plunger pump.

Background

When the axial plunger pump operates, a rotating assembly in the pump generates centrifugal force, the centrifugal force tends to cause the rotating assembly to deflect, so that a gap is generated between a cylinder body and a port plate, and high-pressure working fluid flows into a pump shell through the gap, so that the plunger pump cannot operate in an optimal state. To avoid the rotating assembly from skewing, the rotational speed of the plunger pump has to be limited.

In the prior art, in order to reduce the centrifugal force of the rotating assembly, one measure is to use a hollow plunger, which enables the weight of the rotating assembly to be reduced, i.e. the centrifugal force is correspondingly reduced. Another measure is to increase a spring for urging the cylinder toward the port plate to reduce a clearance between the cylinder and the port plate as much as possible. However, the maximum allowable rotational speed of the axial piston pumps of the prior art is still limited.

SUMMERY OF THE UTILITY MODEL

It is an object of the present application to provide an axial plunger pump which is capable of increasing the maximum allowable rotational speed of the pump.

To this end, the present application provides, in one aspect thereof, an axial plunger pump comprising: a pump housing formed of a housing body and a rear cover, the housing body having an end wall and a peripheral wall extending forwardly from the end wall; a drive shaft carried by the pump housing; a cylinder block provided in the pump housing, the cylinder block being rotatably driven by the drive shaft, the cylinder block having a plurality of plunger chambers formed therein, one plunger being slidably inserted in each plunger chamber; the cylinder body is provided with an oil port which radially extends to the periphery of the cylinder body from the front end of each plunger cavity; the axial plunger pump further comprises a flow distribution ring which is fixed in the peripheral wall and surrounds the periphery of the cylinder body to form a sliding bearing for supporting the cylinder body to rotate, and the flow distribution ring is provided with an oil discharge groove and an oil suction groove at axial positions corresponding to the oil ports.

In one embodiment, an oil discharge port that maintains communication with the oil discharge groove and an oil suction port that maintains communication with the oil suction groove are formed in the peripheral wall.

In one embodiment, the oil discharge groove and the oil suction groove each extend in the circumferential direction in the flow distribution ring by a corresponding arc.

In one embodiment, the distribution ring is cylindrical made of copper.

In one embodiment, the axial plunger pump further comprises a pressure-bearing ring disposed in a rear end face of the rear cover, and the front end of the cylinder body is slidably urged against the pressure-bearing ring.

In one embodiment, the pressure ring is a flat circular ring made of copper.

In one embodiment, the front end of the cylinder is configured as an annular protrusion projecting forwardly from the body portion of the cylinder, the annular protrusion having a wall thickness less than the radial width of the pressure bearing ring.

In one embodiment, the drive shaft is supported by bearings in the end walls, with a forward portion of the drive shaft being fixed in a rearward portion of the cylinder block.

In one embodiment, the cylinder is formed with a central cavity facing forward in which a spring is disposed, the rear end of the spring being supported by the front end of the drive shaft, the front end of the spring applying a forward thrust to the cylinder.

In one embodiment, each plunger is a closed hollow structure having an internal hollow that is closed with respect to the exterior of the plunger.

According to the present application, a distribution ring on the side of the cylinder is used in an axial piston pump to suck and discharge the working fluid, the distribution ring simultaneously acting as a sliding bearing supporting the cylinder. In this way, the rotating cylinder can be supported by the distribution ring, and the maximum allowable rotation speed of the pump can be increased by resisting the radial centrifugal force generated by the rotation of the cylinder.

Drawings

The foregoing and other aspects of the present application will be more fully understood and appreciated by reference to the following detailed description, taken with reference to the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of an axial piston pump according to one possible embodiment of the present application;

fig. 2 is an expanded view of a flow distribution ring in the axial plunger pump.

Detailed Description

The present application relates generally to an axial piston pump, one embodiment of which is schematically illustrated in fig. 1. It should be noted that the construction of the axial piston pump is shown schematically, not to scale, and that certain elements and details have been omitted from the drawings in order to clearly embody the principles of the present application.

As shown in fig. 1, the axial plunger pump includes a pump housing constituted by a cylindrical housing 1 and a rear cover 2. The housing 1 is constituted by a peripheral wall 1a and an end wall 1b, defining an inner space. The rear cover 2 closes the inner space. The peripheral wall 1a extends forward (i.e., toward the rear cover 2) from the end wall 1 b.

A drive shaft 3 is carried by the housing 1. The drive shaft 3 passes through the end wall 1b and is supported by bearings in the end wall 1 b. The drive shaft 3 defines a rotational axis.

In the inner space of the housing 1, the functional elements of the plunger pump are arranged, which are described in turn below.

A cylinder block 4 is fixedly supported on a front portion of the drive shaft 3 such that the cylinder block 4 can be driven to rotate by the drive shaft 3.

The cylinder 4 has formed therein a plurality of plunger chambers 5 arranged parallel to each other around the rotational axis. The front end of each plunger cavity 5 leads to the front end surface of the cylinder body 4, and the rear end thereof is communicated with the rear end surface of the cylinder body 4.

Each plunger chamber 5 has inserted into it from the rear end a corresponding plunger 6, each plunger 6 being axially slidable in the plunger chamber 5 and each plunger 6 rotating with the cylinder 5.

A ball head 7 is formed or attached to a rear end of each plunger 6 that emerges from the plunger cavity 5, the ball head 7 being inserted into a respective slipper 8 such that each slipper 8 is able to rotate relative to the respective ball head 7.

A swash plate (also referred to as a variable head) 9 is disposed on the rear side of each shoe 8, and the rear end surface (bottom surface) of each shoe 8 slidably pushes against the front surface of the swash plate 9. A return disc, not shown, keeps the shoes 8 simultaneously pushed against the swash plate 9.

The swash plate 9 is inclined with respect to the rotational axis of the drive shaft 3. The drive shaft 3 passes through the swash plate 9, and the swash plate 9 does not rotate with the drive shaft 3.

Optionally, the swash plate 9 is swingable about a swing axis to adjust the inclination angle of the swash plate. For this purpose, a variable displacement mechanism (not shown) is provided in the plunger pump for driving the swash plate 9 to oscillate. Various forms of variable mechanisms known in the art may be used herein and are not shown or described herein.

Further, the rear end portion of the cylinder block 4 is fixed around the front portion of the drive shaft 3. The front end 10 of the cylinder 4 faces a pressure ring 11 provided in the rear end surface of the rear cover 2. The pressure ring 11 is made of a wear-resistant material, such as copper, in a flat circular ring shape, and is fixed to the rear end face of the rear cover 2, such as being embedded in an annular groove in the rear end face of the rear cover 2. When the driving shaft 3 rotates, it rotates the cylinder 4, and the front end 10 of the cylinder 4 slides and rotates along the pressure ring 11.

The front end 10 of the cylinder 4 may be configured in the form of a circular ring-shaped protrusion protruding forward from the body portion of the cylinder 4. The wall thickness of the annular protrusion is smaller than the radial width of the pressure ring 11.

The cylinder block 4 is formed with a central cavity facing forward, into which the front end of the drive shaft 3 is inserted a short distance. In the central cavity, a spring support 12 is arranged, which spring support 12 is fixed to the front end of the drive shaft 3. The rear end of the spring 13 is axially urged against the spring support 12, and the front end is axially urged against a snap ring 14 fixed in the front of the cylinder 4. Thus, the spring 13 applies a forward urging force to the cylinder 4 via the snap ring 14 to urge the front end 10 of the cylinder 4 against the pressure ring 11.

Around the outer circumference of the cylinder 4 is arranged a distribution ring 15. The distribution ring 15 has an oil discharge side and an oil suction side. An oil discharge groove 16 is formed in the oil discharge side of the flow distribution ring 15, and an oil suction groove 17 is formed in the oil suction side.

The inner periphery of the flow distribution ring 15 supports the outer periphery of the cylinder 4 so that the cylinder 4 can slidably rotate within the flow distribution ring 15. The outer periphery of the distribution ring 14 is tightly fixed to the inner peripheral surface of the corresponding portion of the peripheral wall 1 a.

At the front of the cylinder 4, an oil port 18 is formed extending radially outward from the front end of each plunger chamber 5 to the outer periphery of the cylinder 4. The oil discharge groove 16 and the oil suction groove 17 are provided at axial positions communicating with the respective oil ports 18 so as to establish communication with the respective oil ports 18.

Further, an oil discharge port 19 and an oil suction port 20 extending in the radial direction are formed in the peripheral wall 1 a. The oil discharge port 19 is in communication with the oil discharge groove 16, and the oil suction port 20 is in communication with the oil suction groove 17.

Fig. 2 shows an expanded view of the distribution ring 15. The distribution ring 15 may be considered as a cylinder formed by longitudinal end-to-end joining of an elongated sheet. The oil discharge groove 16 and the oil suction groove 17 are long holes formed in the flow distribution ring 15, i.e., each extend in a certain arc in the circumferential direction.

Returning to fig. 1, when the cylinder block 4 is rotated by the drive shaft 3, the respective plungers 6 and shoes 8 rotate with the cylinder block 4, and the respective shoes 8 slide on the front surface of the swash plate 9. Due to the swing angle of the swash plate 9, each plunger 6 on the oil suction side is retreated relative to the cylinder block 4 to suck the working fluid into the corresponding plunger chamber 5 from the oil suction port 20 through the corresponding oil port 18 and oil suction groove 17, and each plunger 6 on the oil discharge side is advanced relative to the cylinder block 4 to pressurize the working fluid in the corresponding plunger chamber 5 and discharge the same through the corresponding oil port 18 and oil discharge groove 16 via the oil discharge port 19.

The distribution ring 15 constitutes a sliding bearing of the cylinder 4 during rotation of the cylinder 4 to support the cylinder 4. Since the flow distribution ring 15 is supported, the centrifugal force of the cylinder 4 is offset by the flow distribution ring 15, which can prevent the cylinder 4 from tilting.

In order to be able to be used as a sliding bearing, the distribution ring 15 is made of a wear-resistant material, for example copper.

In addition, a small amount of the working fluid inevitably leaks out of the oil drain groove 16, and enters a minute gap between the outer periphery of the cylinder 4 and the inner periphery of the distribution ring 15 to form an oil film. This oil film contributes to the sliding support effect of the distribution ring 15.

Due to the supporting function of the flow distribution ring 15 on the cylinder body 4, the structural rigidity of the cylinder body 4 and the driving shaft 3 is improved. Therefore, the drive shaft 3 can be supported only by the bearing in the end wall 1b as shown in fig. 1, and it is not necessary to provide a bearing in the rear cover 2 to support the front end of the drive shaft 3. Meanwhile, the front end of the drive shaft 3 may protrude into only the rear portion of the cylinder block 4. Thus, the length of the drive shaft 3 is shortened, and the centrifugal force generated by the drive shaft 3 can be reduced.

The plunger 6 may have a hollow structure with a front end opened to the plunger chamber and a rear end formed with a passage to the slipper 8, so that the working fluid is supplied to the slipper 8 and to the interface between the slipper 8 and the swash plate 9 through the passage in the slipper 8 as a lubricant. According to a further aspect of the present application, each plunger 6 may be configured as a closed hollow structure. On the one hand, the plunger 6 has an internal hollow to reduce the weight of the plunger 6 and therefore its moment of inertia, increasing mechanical efficiency. On the other hand, the inner hollow is closed with respect to the outside of the plunger 6, and no working fluid can enter the inner hollow. In this way, the dead volume of the plunger cavity 5 can be reduced relative to a plunger having an open cavity, so that hydraulic efficiency can be improved.

The axial piston pump of the present application is preferably used as a closed piston pump, i.e., the working fluid discharged through the oil discharge port 19 drives the hydraulic actuator and then returns to the oil suction port 20, thereby forming a closed circulation path for the working fluid.

Various modifications to the embodiments described above will be apparent to those skilled in the art, given the benefit of the teachings of this application.

According to the present application, a distribution ring on the side of the cylinder is used in an axial piston pump to suck and discharge the working fluid, the distribution ring simultaneously acting as a sliding bearing supporting the cylinder. In this way, the rotating cylinder can be supported by the distribution ring, resisting the radial centrifugal force generated by the rotation of the cylinder, thus allowing to increase the maximum allowable rotation speed of the pump.

In addition, in the case of the plungers configured in the closed hollow structure, on the one hand, the weight of each plunger can be reduced, and on the other hand, the volume of the working fluid dead space in the plunger cavity can be reduced, which can improve the pump efficiency.

Although the present application has been described herein with reference to particular embodiments, the scope of the present application is not intended to be limited to the details shown. Various modifications may be made to these details without departing from the underlying principles of the application.

Claims

1. An axial plunger pump comprising:

a pump housing formed of a housing (1) and a rear cover (2), the housing having an end wall (1b) and a peripheral wall (1a) extending forward from the end wall;

a drive shaft (3) carried by the pump housing;

a cylinder (4) disposed in the pump housing, the cylinder being rotatably driven by the drive shaft, the cylinder defining a plurality of plunger chambers (5) each having a plunger (6) slidably inserted therein;

characterized in that the cylinder body is formed with oil ports (18) extending radially from the front end of each plunger cavity to the outer periphery of the cylinder body, respectively;

the axial plunger pump further comprises a flow distribution ring (15) fixed in the peripheral wall and forming a sliding bearing around the outer periphery of the cylinder body to support the cylinder body for rotation, the flow distribution ring being provided with an oil discharge groove (16) and an oil suction groove (17) at axial positions corresponding to the respective oil ports.

2. The axial plunger pump according to claim 1, characterized in that an oil discharge port (19) that is held in communication with the oil discharge groove and an oil suction port (20) that is held in communication with the oil suction groove are formed in the peripheral wall.

3. The axial piston pump as defined in claim 1, wherein said oil discharge groove and said oil suction groove each extend in said port ring in a corresponding arc in a circumferential direction.

4. The axial piston pump as recited in claim 1, wherein said flow distribution ring is cylindrical and formed of copper.

5. Axial piston pump according to any one of claims 1-4, further comprising a pressure-bearing ring (11) arranged in the rear end face of the rear cover, against which the front end (10) of the cylinder is slidably pushed.

6. The axial piston pump as recited in claim 5, wherein said bearing ring is a flat circular ring made of copper.

7. The axial plunger pump of claim 5, wherein the front end of the cylinder is configured as an annular protrusion protruding forward from the body portion of the cylinder, the annular protrusion having a wall thickness smaller than a radial width of the pressure-bearing ring.

8. Axial piston pump according to any one of claims 1-4, characterised in that the drive shaft is supported by bearings in the end walls, the front part of the drive shaft being fixed in the rear part of the cylinder block.

9. Axial piston pump according to claim 8, characterised in that the cylinder is formed with a central cavity facing forwards, in which a spring (13) is arranged, the rear end of which is supported by the front end of the drive shaft, the front end of which applies a forward thrust to the cylinder.

10. The axial plunger pump of any of claims 1-4, wherein each plunger is of closed hollow construction having an internal hollow closed to the exterior of the plunger.