JP2003148326A - Cylinder device and axial piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder device and an axial piston pump capable of preventing bursting damages of bellows even if pressure in the bellows increases. SOLUTION: The cylinder device and the axial piston pump are provided with a cylinder 2 having a piston bore 5, and having an inflow part 8 and an outflow part 9 of a hydraulic fluid, a piston 3 inserted into the piston bore 5, and forming a pressurizing chamber 16 for communicating with the inflow part 8 and the outflow part 9, and the bellows 4 arranged between the piston 3 and a piston bore 5 part other than the pressurizing chamber 16, and separating the hydraulic fluid from a lubricating fluid of the piston 2. The piston 3 has a head part 17, and a piston rod part 18. The bellows 4 are fitted around the piston rod part 18, and one end part is brought into close contact with a position near the head part 17, and the other end part is brought into close contact with the piston bore 5 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device and a swash plate type axial piston pump having a seal member for preventing mixing of a working fluid actuated by or actuating the piston with a lubricating fluid of the piston. It is a thing.

[0002]

2. Description of the Related Art A conventional cylinder device of this type is a device capable of reciprocally driving a piston to pump a working fluid, or pressurizing and decompressing a working fluid in a cylinder chamber to reciprocally drive a piston. However, pistons require a lubricating fluid to receive or transmit power. For this reason,
A working fluid that leaks through a very narrow gap between the inner surface of the cylinder chamber and the piston may be mixed in with the lubricating fluid, which becomes a problem when it is necessary to avoid such mixing.

For example, in a swash plate type piston pump that handles liquids other than oil, when the rotary drive unit and the reciprocating drive unit and the piston unit are in the same housing, basically all of them are under the environment of the liquid to be handled. Since the bearings, swash plates, shoes, etc. are placed in the position where wear resistance and corrosion resistance are significantly reduced, the life of the piston pump is shortened. In order to avoid this, special materials and parts are used, which is expensive.

Therefore, the first conventional example (for example, Japanese Patent Laid-Open No. 8-
No. 254185) uses the same quality of the working fluid and the lubricating fluid and eliminates the need for a seal member for sealing the working fluid and the lubricating fluid.

Second conventional example (for example, Japanese Patent Laid-Open No. 10-318123)
In order to seal the working fluid and the lubricating fluid, the bellows is fitted on the cylinder, one end is in close contact with the tip of the piston rod, and the other end is in close contact with the middle of the outer peripheral surface of the cylinder. There is. This prevents the working fluid from leaking from the cylinder to the sliding contact portion between the piston rod and the swash plate.

[0006]

In the first conventional example, when the working fluid is, for example, clean drinking water, even if the lubricating fluid is water, mixing them is not preferable in terms of hygiene.
Therefore, it is necessary to completely seal the lubricating fluid and the working fluid.

In the second conventional example, the pressure in the bellows increases as the piston moves in the pressurizing direction, and the bellows may swell and rupture. If the bellows breaks, the lubricating fluid and the working fluid mix. There is a high possibility.
On the other hand, if the stroke of the piston is shortened to avoid bursting, a pump with a large discharge amount cannot be obtained.

Accordingly, an object of the present invention is to provide a cylinder device and an axial piston pump which can prevent the bellows from bursting and damaging even if the pressure inside the bellows increases.

[0009]

According to a first aspect of the present invention, there is provided a cylinder device having a piston bore, the cylinder having a working fluid inflow portion and an outflow portion formed in the piston bore, and the cylinder device being inserted into the piston bore. A piston forming a pressurizing chamber communicating with the inflow part and the outflow part, and the working fluid provided between the piston bore portion other than the pressurizing chamber and the piston And a seal member for separating.

According to the cylinder device of the first aspect, the working fluid can be prevented from being mixed with the lubricating fluid of the piston by the sealing member, and the working fluid or the lubricating fluid can be provided because the sealing member is provided in the cylinder bore. Since the seal member can be supported by the inner surface of the cylinder bore or the piston even if the seal member swells due to the pressure due to, the rupture of the seal member can be prevented.

A cylinder device according to a second aspect is the cylinder device according to the first aspect.
In the above, the piston has a head portion and a piston rod portion, and the seal member is a bellows externally fitted to the piston rod portion, one end of which is closely attached to a position near the head portion and the other end is It comes into close contact with the piston bore side.

According to the cylinder device of the second aspect, the same effect as that of the first aspect can be obtained.

In the axial pump according to a third aspect of the present invention, a plurality of cylinder devices according to the second aspect are arranged in an annular shape with their axial directions parallel to each other, and a swash plate is slidable at the tip of each piston rod portion of the cylinder. At least one of the plurality of cylinders or the swash plate comes into contact with each other and rotates relative to the other.

According to the axial pump of the third aspect, the same effect as that of the first aspect can be obtained.

An axial pump according to a fourth aspect of the present invention is the axial pump according to the third aspect, wherein the end portion of the piston bore of the cylinder is closed by a shield and guide plate having a through hole that penetrates each of the piston rod portions. The other end is in close contact with the shield and guide plate facing the piston bore, and the piston rod part has a spiral groove formed on the peripheral surface thereof, and the swash plate and the swash plate are provided in a container part filled with a lubricating fluid. The tip of the piston rod is located.

According to the axial pump of the fourth aspect, in addition to the same effect as that of the first aspect, the piston bore can be closed by the shield and guide plate, and the lubricating fluid passes through the spiral groove, so that the through hole and the piston are provided. It is possible to lubricate the rod portion. Also, in order to support the piston rod part with the through hole, when sliding the piston rod part to the swash plate,
It is possible to prevent galling due to a bending moment in the radial direction which occurs when the piston rod portion reciprocates.

The axial pump according to a fifth aspect of the present invention is the axial pump according to the fourth aspect, wherein each of the inflow portion and the outflow portion has a cartridge type check valve.

According to the axial pump of the fifth aspect, in addition to the same effect as that of the fourth aspect, the check valve's backflow preventing function and the like can be exhibited only by inserting it into the inflow portion and the outflow portion.

According to a sixth aspect of the present invention, in the fifth aspect, the check valve of the inflow section and the check valve of the outflow section have the same structure, and the insertion directions thereof are opposite to each other. .

According to the axial pump of the sixth aspect, in addition to the same effect as the fifth aspect, the flow direction can be controlled only by changing the insertion direction, and the number of check valve parts can be reduced.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. That is, the axial piston pump to which the cylinder device is applied is one in which the swash plate is rotated by the rotation of the main shaft to reciprocate the piston, and the reciprocating motion of the piston sucks and discharges the working fluid.

The cylinder device 1 has a cylinder 2, a piston 3 and a seal member 4.

The cylinder 2 is provided with a cylindrical cylinder portion 7 having high wear resistance at the inner end portion of the piston bore 5 of the body 6 having the piston bore 5, and the working fluid inflow portion is provided on the bottom surface of the piston bore 5. 8 and an outflow portion 9, and open at the end surface of the main body 6. Each of the inflow section 8 and the outflow section 9 is provided with a cartridge type check valve 10. The check valve 10 of the inflow part 8 and the check valve 10 of the outflow part 9 have the same structure, and the insertion directions thereof are opposite to each other. The check valve 10 includes a cylindrical body 11 fitted into the inflow part 8 or the outflow part 9.
A valve seat 12 provided at one end of the tubular body 11, a spherical valve 13 that closes the valve seat 12, a spring support portion 14 with a through hole provided at the other end of the tubular body 11, and one end of the spring support portion 14. Has a coiled spring 15 for supporting the valve 13 against the valve seat 12.

The piston 3 forms a pressure chamber 16 which is inserted into the piston bore 5 and communicates with the inflow portion 8 and the outflow portion 9. The piston 3 has a head portion 17 and a piston rod portion 18. A spiral groove 19 is formed on the circumferential surface of the piston rod portion 18. On the other hand, both ends of the coil-shaped return spring 39 are fitted into the recessed portion 20 formed on the front end surface of the head portion 17 and the recessed portion 21 formed on the facing surface (bottom surface) of the pressurizing chamber 16 so as to be provided in a compressed state. 17 is pressed.

The seal member 4 is provided between the piston bore 5 other than the pressurizing chamber 16 and the piston 2 to separate the working fluid from the lubricating fluid of the piston 2, and has, for example, elasticity. This seal member 4 is a piston rod portion 1.
8 is a bellows made of metal, for example, which is fitted on the outside of the piston 8. One end of the bellows is in close contact with the head portion 17 and the other end is in close contact with a guide plate 22 in the piston bore 5, which will be described later.

In the axial piston pump, a plurality of the above-mentioned cylinder devices 1 are arranged in an annular shape with their axial directions parallel to each other, and a swash plate 23 is slidably abutted on the tip of each piston rod portion 18 of the cylinder 2 to provide an oblique movement. A plate 23 is provided on the main shaft 24 and rotates with respect to the cylinder 2.

The body 6 of each cylinder 2 is integrally formed, and a plurality of piston bores 4 are formed in the body 6 in an annular shape. At the center of the body 6, a drain passage 2 that opens at the position of the piston rod portion 18 of the piston bore 5 is formed.
5 is provided and opens in the same direction as the inflow part 8 and the like. The port member 27 is attached to the end surface of the main body 6, and the inflow portion 8
A suction port 28 that communicates with the discharge port 29, a discharge port 29 that communicates with the outflow portion 9, and a drain port 30 that communicates with the drain passage 25 are formed. A shield / guide plate 22 having a through hole 31 for penetrating each of the piston rod portions 18 is provided on the end surface of the main body 6 on the piston rod portion side opposite to the pressurizing chamber 16.
Is attached to close the end of the piston bore 5 of the cylinder 2. The other end of the seal member 4 is in close contact with the shield / guide plate 22 facing the piston bore 5 as described above. A base member 32 is attached to the main body 6 via the guide plate 22. The base member 32 is integrally formed with a mounting portion 33, a bearing portion 34, and a container portion 35. The main shaft 24 is pivotally supported by the bearing portion 34, and the swash plate 23 is provided on the main shaft 24. The container portion 35 accommodates the swash plate 23 and the tip of the piston rod portion 18, and the swash plate 23 is rotatably arranged in the container portion 35. A shoe 36 is provided at the tip of the piston rod portion 18, and the shoe 36 is in sliding contact with the swash plate 23. A lubricating fluid passage hole 37 is formed in the container portion 35, and the container portion 35 is filled with the lubricating fluid through the passage hole 37, so that the swash plate 23 and the piston rod portion 18 are in an oil-immersed state. Further, a passage 38 is provided in the main shaft 24 to connect the interior of the container portion 35 and the bearing portion 34 to supply a lubricating fluid to the bearing portion 34.

The operation of this axial piston pump will be described. When the main shaft 24 is rotated by a motor or the like, the swash plate 23 is rotated and the shoe 36 slides on the surface of the swash plate 23. When the swash plate 23 slides to a highly inclined portion, the piston rod portion 18 of the shoe 36 is pushed by the swash plate 23.
As a result, the piston 3 compresses the pressurizing chamber 16 of the cylinder 2 against the return spring 39, and the valve 13 of the inflow portion 8 is moved to the valve seat 12
The valve seat 13 of the outlet 9 against the spring 15 against the spring 15.
It is pushed up from 2 and the working fluid is pressure-fed from the discharge port 29 to the outside. On the contrary, the piston 3 of the shoe 36, which slides to the low slope portion of the swash plate 23, is pushed by the return spring 39 to expand the pressurizing chamber 16 to a negative pressure, whereby the valve 13 of the inflow portion 8 is made. Is separated from the valve seat 12, the valve 13 of the outflow portion 9 is pressed against the valve seat 12, and the working fluid is sucked into the pressurizing chamber 16. In this way, in each cylinder 2, each piston makes one reciprocation by one rotation of the swash plate 23, and the working fluid is sent under pressure.

The working fluid flows from the pressurizing chamber 16 through the very narrow gap between the cylinder portion 7 and the head portion 17 to the piston bore 5.
If it leaks to the drain port 30, it is drained from the drain port 30 through the drain passage 25. Since the leaked working fluid is partitioned by the seal member 4, it does not flow to the piston rod portion 18. On the other hand, the lubricating fluid in the container portion 35 enters the seal member 4 through the spiral groove 19, but since it is partitioned by the seal member 4, the drain passage 25 and the pressurizing chamber 16 are separated.
The working fluid and the lubricating fluid are completely separated and sealed. When the seal member 4 is filled with the lubricating fluid as the piston 3 reciprocates, the internal pressure increases when the seal member 4 is compressed and the seal member 4 expands, but is supported by the inner peripheral surface of the piston bore 5. Therefore, it is prevented from bursting.

According to this embodiment, the seal member 4 can prevent the working fluid from mixing with the lubricating fluid of the piston 3, and since the seal member 4 is provided in the cylinder bore 5, the pressure of the lubricating fluid can be reduced. Since the seal member 4 can be supported by the inner surface of the cylinder bore 5 even if the seal member 4 swells with, damage to the seal member can be prevented. Therefore, the reciprocating amount of the piston 3 is not limited, and the discharge amount of the working fluid is not abnormally limited.

The shield / guide plate 22 can close the end of the piston bore 5, and since the lubricating fluid passes through the spiral groove 19, the through hole 31 of the guide plate 22 and the piston rod portion 18 can be lubricated. it can. Further, since the piston rod portion 18 is supported by the through hole 31, when the piston rod portion 18 is slidably contacted with the swash plate 23, it is possible to prevent the piston rod portion 18 from being bitten by a bending moment in the radial direction generated when the piston rod portion 18 reciprocates. can do.
Conventionally, the piston part receives an eccentric load in the radial direction due to the rotation of the swash plate and the reciprocating motion of the piston.Therefore, various measures have been taken for the size and shape of the piston and cylinder to prevent the piston and cylinder from being bitten. ing. These were difficult to process and led to higher costs.

Since the inflow portion 8 and the outflow portion 9 each have the cartridge type check valve 10, the check valve 10 can exhibit the backflow prevention function and the like only by being inserted into the inflow portion 8 and the outflow portion 9. Further, since the check valve 10 of the inflow part 8 and the check valve 10 of the outflow part 9 have the same structure and the insertion directions are opposite to each other, the flow direction can be controlled only by changing the insertion direction, and the check valve part The number of varieties decreases.

In the axial piston pump, the swash plate is fixed, the cylinder block is rotatable, the main shaft is connected to the cylinder block, and the cylinder block is rotated with respect to the swash plate to reciprocate the piston. May be. At least one of the swash plate and the cylinder block may rotate relative to the other.

[0034]

According to the cylinder device of the first aspect,
The seal member can prevent the working fluid from mixing with the lubricating fluid of the piston.Because the seal member is provided inside the cylinder bore, the seal member can be attached to the inner surface of the cylinder bore or the piston even if it expands due to the pressure of the working fluid or the lubricating fluid. Since it can be supported, it is possible to prevent the seal member from bursting.

According to the cylinder device of the second aspect, the same effect as that of the first aspect can be obtained.

According to the axial pump of the third aspect, the same effect as that of the first aspect can be obtained.

According to the axial pump of the fourth aspect, in addition to the same effect as that of the first aspect, the piston bore can be closed by the shielding and guide plate, and the lubricating fluid passes through the spiral groove, so that the through hole and the piston are provided. It is possible to lubricate the rod portion. Also, in order to support the piston rod part with the through hole, when sliding the piston rod part to the swash plate,
It is possible to prevent galling due to a bending moment in the radial direction which occurs when the piston rod portion reciprocates.

According to the axial pump of the fifth aspect, in addition to the same effect as that of the fourth aspect, the check valve's backflow preventing function and the like can be exhibited only by inserting it into the inflow portion and the outflow portion.

According to the axial pump of the sixth aspect, in addition to the same effect as the fifth aspect, the flow direction can be controlled only by changing the inserting direction, and the number of parts of the check valve can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a partially enlarged view thereof.

[Explanation of symbols] 1 cylinder device 2 cylinders 3 pistons 4 Seal member 5 piston bore 6 body 7 Cylinder part 8 Inflow section 9 Outflow part 10 check valves 17 Head 18 Piston rod 19 spiral groove 22 Shield and guide plate 23 Swash plate 31 through hole

Claims (6)

[Claims] 1. A cylinder having a piston bore and having an inflow portion and an outflow portion of a working fluid formed in the piston bore, and a pressurizing member which is inserted into the piston bore and communicates with the inflow portion and the outflow portion. A cylinder device comprising: a piston that forms a chamber; and a seal member that is provided between a portion of the piston bore other than the pressurizing chamber and the piston to separate the working fluid from the lubricating fluid of the piston. 2. The piston has a head portion and a piston rod portion, and the seal member is a bellows externally fitted to the piston rod portion, one end portion of which closely contacts a position near the head portion and the other end The cylinder device according to claim 1, wherein the portion is in close contact with the piston bore side. 3. A plurality of cylinder devices according to claim 2, wherein the plurality of cylinder devices are arranged in an annular shape with their axial directions parallel to each other, and a swash plate slidably abuts on the tip of each piston rod portion of the cylinder. Alternatively, an axial piston pump in which at least one of the swash plates rotates relative to the other. 4. An end portion of the piston bore of the cylinder is closed by a shield and guide plate having a through hole that penetrates each of the piston rod portions, and the other end portion of the bellows faces the piston bore. 4. The piston rod portion is closely attached to the shield / guide plate, a spiral groove is formed on the peripheral surface of the piston rod portion, and the swash plate and the tip end of the piston rod are located in a container portion filled with a lubricating fluid. Axial piston pump. 5. The axial piston pump according to claim 4, wherein each of the inflow section and the outflow section has a cartridge type check valve. 6. The axial piston pump according to claim 5, wherein the check valve of the inflow portion and the check valve of the outflow portion have the same structure, and the insertion directions thereof are opposite to each other.