JPH05231301A - Axial piston type pump - Google Patents

Abstract

PURPOSE:To provide an axial piston type pump which has excellent suction performance and is suitable for high speed running. CONSTITUTION:A communicating path 50 is provided in an endblock 2 and an introducing path 51 is provided to a swash plate 15. One end 50a of the communicating path 50 opens to a suction hole 25 the other end 50b opens to the inner space of a casing 1. One end of the introducing path 51 opens in such a way as communicating with the penetrating hole 14 of a piston 12 through the inner hole 20 of a hollow slipper 17 inside the suction area of the piston 12, and also the other end of the introducing path 51 opens in such a way as communicating with the inner part of the casing 1 near the outer peripheral edge of the swash plate 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial piston pump used in various industrial machines, and more particularly to an axial piston type pump having excellent suction performance.

[0002]

2. Description of the Related Art Axial piston type pumps of this type have various structures such as a slant shaft type or a swash plate type as described in, for example, "Sadao Ishihara: Theory and Practice of Piston Pumps and Motors". It is known that, of these structures, a fixed displacement axial piston hydraulic pump in which the cylinder rotates is configured as shown in FIG.

That is, the pump shown in FIG. 4 has a one-end opening type casing 1 and an end block 2 for closing the opening end of the casing 1, and a main shaft 3 is arranged in the casing 1 so as to penetrate the inner and outer bottom surfaces of the casing 1. The main shaft 3 is rotatably supported by a bearing 4a on the inner surface side of the end block 2 and a bearing 4b embedded between the inner and outer bottom surfaces of the casing 1. A fluid seal is provided between the casing 1 and the main shaft 3 via a seal 5 and a seal box 6.

A cylinder block 8 is provided in the casing 1, and the cylinder block 8 is attached to the main shaft 3 through an inner hole 7 thereof.
A part of the inner hole 7 is formed as a spline hole 9, while a spline 10 is formed on a part of the main shaft 3, and the spline hole 9 and the spline 10 are engaged with each other, and It is configured to transmit the rotation of the main shaft 3 to the cylinder block 8.

Further, the cylinder block 8 is provided with seven cylinders 11 and 1 on the radiation centering on the inner hole 7.
1 are provided, and pistons 12 are inserted into these cylinders 11, respectively. The piston 12 has a spherical engagement protrusion 13 and a through hole 1.
4 is provided, the engagement protrusion 13 is formed on one end side of the piston 12, and the through hole 14 is formed so as to penetrate between both ends of the piston 12.

By the way, on the one end face side of the cylinder block 8, the inner bottom face of the casing 1 is the fixed swash plate 1.
5 is formed, and the swash plate 15 is set to incline at a predetermined angle with respect to the main shaft 3.

A slipper 16 is provided between the piston 12 and the swash plate 15, and the slipper 16 is provided.
Is a plurality of hollow slippers 17 integrated by a retainer 18. Each hollow slipper 17 is provided with an engaging portion 19 and an inner hole 20, and the engaging portion 19 engages with the engaging protrusion 13 of the piston 12. It is formed to fit. Inner hole 2
No. 0 is provided so that the through hole 14 of the piston 12 communicates with the swash plate 15. On the other hand, the retainer 18 is attached to the main shaft 3 via a retainer ball 21, and a compression spring 22 is interposed between the retainer ball 21 and the cylinder block 8. That is, such a slipper 16
Is slidably provided on the swash plate 15 while being urged toward the swash plate 15 by the repulsive force of the compression spring 22.

Further, a valve plate 23 is attached to the inner surface of the end block 2 by a fixing pin 24, and an intake port 25 and a discharge port 26 are formed in the end block 2. The discharge port 26 is configured to communicate with the inside of the cylinder 11 via the valve holes 27, 27 of the valve plate 23.

That is, in such a pump, when a pulley (not shown) fixed to the main shaft 3 with the key 28 is rotated, the cylinder block 8 rotates integrally with the main shaft 3. At this time, the rotational force of the main shaft 3 is transmitted from the cylinder block 8 to the slipper 16 via the piston 12 in the cylinder 11.
The slipper 16 rotates while sliding on the swash plate 15 following the rotation of the piston 12.

As a result, the piston 12 is moved to the cylinder 11
While reciprocating back and forth within the cylinder, as the piston 12 moves backward, the intake port 25 allows the cylinder 1 to pass through the valve hole 27.
The fluid is sucked into the inside of the cylinder 1, and when the piston 12 moves forward, the fluid is discharged from the inside of the cylinder 11 at the discharge port 26. Further, at the same time as the suction / discharge operations, the oil in the cylinder 11 penetrates the sliding surface of the swash plate 15 and the slipper 16 through the through hole 14 of the piston 12 and the inner hole 20 of the hollow slipper 17.
Is supplied via.

[0011]

However, in such a conventional pump, as described above, the cylinder 11 is used.
Since there is only one passage through which the oil is sucked into the cylinder 11, the flow velocity of the oil sucked into the cylinder 11 from the suction port 14 during high-speed operation, that is, when the rotation speed of the cylinder block 8 is increased. Becomes unable to follow the backward speed of the piston 12, the oil is depressurized in the cylinder 11, and the air in the oil forms air bubbles, which not only causes cavitation, but also causes insufficient operating noise due to insufficient oil suction. Is increased, the discharge amount is small relative to the rotation speed, or an unbalanced load is increased on the sliding surface between the cylinder block 8 and the valve plate 23, the sliding surface between the swash plate 14 and the hollow slipper 17, or the like. There is a problem that a problem occurs and it is not suitable for high speed operation.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an axial piston pump having excellent suction performance and suitable for high speed operation.

[0013]

In order to achieve the above object, the present invention relates to a fluid suction hole and a discharge hole formed in an end block which closes an opening end of a one-end opening type casing, and a rotation inside the casing. A cylinder block that is movably arranged, a piston that is fitted into a plurality of cylinders of the cylinder block, and a through hole that penetrates between both ends of the piston are provided, and the piston is linked with the rotation of the cylinder block. In a swash plate type or swash shaft type axial piston type pump that sucks fluid into the cylinder from the suction hole by reciprocating back and forth and then discharges the fluid in the cylinder from the discharge hole, And a communication passage having the other end opened inside the casing, and one end opened inside the casing and the piston Characterized in that the provided introduction passage which opens at the other end to the through hole of the piston in the suction region.

[0014]

According to the present invention, in the suction area of the piston, there are two paths, that is, a path through the suction hole and a path from the communication path through the casing to the introduction path and the through hole of the piston. Fluid is sucked into the cylinder.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pump according to the present invention will be described in detail below with reference to FIGS. The same members as those of the related art are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a sectional view of the pump. In FIG. 1, the end block 2 is provided with a communication passage 50, and one end 50a of the communication passage 50 is opened to the suction hole 25. The other end 50b is the valve plate 2
An opening is made inside the casing 1 in the vicinity of 3.

An introduction path 51 is provided on the inner bottom surface of the casing 1, that is, the swash plate 15, and the introduction path 51 is provided.
2 is formed by combining a semi-circular groove 52 and a radial groove 53 as shown in FIG. 2. The semi-circular groove 52 is located in the suction area A _IN of the piston 12 and the hollow slipper 17 is provided.
Is provided on the locus a of the inner hole 20 provided in the. In addition,
The width of the semi-circular groove 52 is formed to have substantially the same size as the inner diameter of the inner hole 20. On the other hand, the radial grooves 53 are radially provided from the semicircular arc groove 52 to the outer peripheral edge of the swash plate 15.

That is, with respect to the introduction path 51 formed by the combination of the semi-circular groove 52 and the radial groove 53, one end thereof, that is, the end 52a of the semi-circular groove 52, has a suction area A of the piston 12. It is opened in the _IN so as to communicate with the through hole 14 of the piston 12 through the inner hole 20 of the hollow slipper 17, and the other end, that is, the end portion 53a of the radial groove 53 is located near the outer peripheral edge of the swash plate 15 in the casing 1. It is opened to communicate with the inside of the.

The suction area A _IN is the piston 1
2 is closest to the valve plate 23 side (hereinafter,
A position farthest from the valve plate 23 by retracting from the most advanced position (hereinafter referred to as last retracted position)
It is a range in which the hollow slipper 17 is rotated while sliding on the swash plate 15 until reaching the point. On the other hand, the discharge area A _OUT is a range in which the hollow slipper 17 slides on the swash plate 15 while the piston 12 moves from the last retracted position to the most advanced position.

Next, the operation of the pump configured as described above will be described with reference to FIGS. 1 and 2. Since the piston 12 reciprocates back and forth in the cylinder 11 following the rotation of the cylinder block 8,
Detailed description thereof will be omitted.

According to this pump, while the piston 12 is retracting from its most advanced position to its most retracted position, that is, in the suction area A _{IN of the} piston 12, the fluid is the suction hole 25 and the valve hole of the valve plate 23. While being sucked into the cylinder 8 via 27, the communication passage 50, the inside of the casing 1, the introduction passage 51, the inner hole 20 of the hollow slipper 17,
And the through hole 14 of the piston 12 in that order, and the cylinder 8
Is sucked in.

Further, while the piston 12 advances from its last retracted position to the most advanced position, that is, in the discharge area A _{OUT of the} piston 12, the inner hole 20 of the hollow slipper 17 is formed.
Is closed by the surface of the swash plate 15, the piston 12 advances. As a result, the fluid in the cylinder 11 is discharged from the discharge hole 26 via the valve hole 27 of the valve plate 23.

FIG. 3 shows a second embodiment in which the pump according to the present invention is applied to an oblique shaft type axial piston type pump, and the pump is arranged at a main shaft 70 and at an inclination with respect to the main shaft 70. The main shaft 70 and the sub shaft 71 are connected to each other at one end via a gear joint 72.

Further, the cylinder block 8 is attached to the sub shaft 71 by spline connection, but the piston 12 is inserted into the cylinder 11 of the cylinder block 8 as in the first embodiment. Therefore, its detailed description is omitted.

On the other hand, a flange-shaped slipper 72 is integrally formed on one end side of the main shaft 70, and a side plate 73 is arranged so as to surround the main shaft 70. The slipper 72 and the side plate 73 are separated from each other. It is provided so as to be in sliding contact with each other.

Further, the slipper 72 has an engaging portion 19
And the inner hole 20, and the engaging portion 19 is formed so as to engage with the engaging protrusion 13 of the piston 12. The engagement protrusion 13 is fixed by the retainer 74 so as not to come off the engagement portion 19. The inner hole 20 is formed so that the through hole 14 of the piston 12 communicates with the side plate 73.

Further, such a pump is also provided with a communication passage 50 and an introduction passage 51 similar to those of the first embodiment.
However, in this pump, the introduction path 51 is formed in the side plate 73 instead of the swash plate 15 described in the first embodiment.

Even in the pump constructed as described above, while the piston 12 is retracting from its most advanced position to its most retracted position, that is, in the suction region of the piston 12, the fluid is sucked into the suction holes 25 and While being sucked into the cylinder 11 through the valve hole 27 of the valve plate 23, the communication passage 50, the inside of the casing 1, the introduction passage 51, the inner hole 20 of the slipper 72, and the through hole 14 of the piston 12 are formed.
And then sucked into the cylinder 11.

Therefore, according to the above embodiment, in the suction region of the piston, there are two routes, that is, the route through the suction hole or the like and the route from the communication passage through the casing to the introduction route or the like. Then, since the fluid is sucked into the cylinder, the suction performance is increased, and the flow velocity of the oil sucked into the cylinder follows the backward speed of the piston even during high-speed operation of the pump, so that only cavitation can be reduced. Moreover, it is possible to prevent an increase in operating noise due to insufficient suction of oil.

In addition to the above-mentioned embodiment, the axial piston type pump has a piston whose tip is formed into a spherical shape or a cup shape, which can change the reciprocating distance of the piston, or for transmitting rotation of the main shaft. There are various types having special structures, etc., but the communication passage and the introduction passage, which are the characteristic portions of the present invention, can be applied to these various pumps.

[0031]

As described above, in the axial piston type pump according to the present invention, in the suction region of the piston as described above, the passage through the suction hole and the introduction passage through the communication passage through the casing and the through hole of the piston are provided. Since the fluid is sucked into the cylinder through the two paths, that is, the path through the, the suction performance is increased, and the flow velocity of the oil sucked into the cylinder follows the backward speed of the piston even during high-speed operation of the pump. Therefore, in particular, not only cavitation can be reduced, but also an increase in operating noise due to insufficient suction of oil can be prevented, an excellent suction performance can be provided, and an axial piston type pump suitable for high speed operation can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a pump according to the present invention.

FIG. 2 is an explanatory diagram illustrating a main part of the present invention.

FIG. 3 is a sectional view showing another embodiment of the pump according to the present invention.

FIG. 4 is a sectional view illustrating a conventional pump.

[Explanation of symbols]

 1 Casing 2 End Block 8 Cylinder Block 11 Cylinder 12 Piston 14 Through Hole 25 Suction Hole 26 Discharge Hole 50 Communication Passage 51 Inlet Passage

Claims (1)

[Claims] 1. A fluid suction hole and a fluid discharge hole formed in an end block that closes the opening end of the one-end opening type casing,
A cylinder block rotatably arranged in the casing, a piston fitted into a plurality of cylinders included in the cylinder block, and a through hole penetrating between both ends of the piston are provided, and the cylinder block is rotated. In a swash plate type or swash shaft type axial piston type pump that discharges fluid in the cylinder from the discharge hole after sucking fluid into the cylinder from the suction hole by reciprocally moving the piston back and forth in conjunction with each other, A communication passage having one end opened to the suction hole and the other end opened to the inside of the casing, and one end opened to the inside of the casing and the other end opened to the through hole of the piston in the suction region of the piston. The axial piston type pump is characterized by having the above-mentioned introduction passage.