JP2001349302A - Hydraulic power package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic power package with high operation efficiency by reducing working loss caused by inflow and outflow of working fluid to a tank. SOLUTION: In this hydraulic power package in which the operating direction of a cylinder is changed over depending on the direction of working fluid delivered by a pump, and the working fluid of the portion of rod volume flows in and out of the tank 3 with expansion and contraction of the cylinder. The hydraulic power package is provided with a bladder hollow elastic body 13 demarcating the tank 3, whereby the capacity of the tank 3 is varied with the elastic deformation of the hollow elastic body 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a hydraulic power package for causing a cylinder to expand and contract by a working fluid pressure.

[0002]

2. Description of the Related Art As this kind of hydraulic power package,
There are pumps, electric motors, valves, tanks, and other units.

Conventionally, a hydraulic circuit shown in FIG. 4 has been proposed in Japanese Utility Model Laid-Open Publication No. Hei 7-2606 as a hydraulic circuit used for a working machine or the like.

[0004] To explain this, the present apparatus comprises first and second passages 21 and 22 connecting the bidirectional pump 2 and the cylinder 1.
A closed circuit is formed with the tank 3 by switching the rotation direction (discharge direction) of the pump 2 driven by the forward / reverse rotation motor 4 to switch the expansion / contraction operation direction of the cylinder 1.

The first and second passages 21 and 22 are provided with direction switching valves 20 for switching the flow of the working fluid. The directional control valve 20 supplies the working fluid discharged from the pump 2 to the chamber 11,
Check valves 23 and 24 leading to the chamber 12 and operating check valves 25 and 26 for returning the working fluid flowing out of the chambers 11 and 12 to the tank 3. The working fluid is supplied to the chambers 11 and 12 according to the discharge direction of the pump 2. The working fluid flowing out of the other one of the chambers 11 and 12 is returned to the tank 3 while being supplied to one of the selected chambers. Thereby, the cylinder 1
The air is prevented from staying inside.

When the cylinder 1 is extended, the pump 2 is rotated forward, the working fluid in the tank 3 is sucked into the pump 2 through the check valve 27, and the second passage 22
Working fluid discharged to the chamber 12 through the check valve 24
Sent to As the pressure in the second passage 22 rises, the operation check valve 25 opens, and the working fluid in the chamber 11 is returned to the tank 3 via the operation check valve 25.

On the other hand, when the cylinder 1 is contracted, the pump 2 is rotated in the reverse direction, and the working fluid in the tank 3 is supplied to the check valve 2.
The working fluid sucked into the pump 2 through the pump 8 and discharged from the pump 2 to the first passage 21 is sent to the chamber 11 through the check valve 23. As the pressure in the first passage 21 rises, the operation check valve 26 opens, and the working fluid in the chamber 12 is returned to the tank 3 via the operation check valve 26.

FIG. 5 shows the above-described bidirectional pump 2, the check valves 23 to 28, the operating check valves 25 and 26, and the relief valves 29 and 30 housed in the manifold block 5.
FIG. 3 is a plan view of a hydraulic power package further including a tank 3 and a forward / reverse rotation motor 4. Ports 21 a, 2 connected to the chambers 11, 12 of the cylinder 1 are provided in the manifold block 5.
2a is open.

FIG. 6 is a sectional view of the tank 3.
Has a cylindrical tubular member 9 and a free piston 6 slidably housed in the tubular member 9. As the cylinder 1 expands and contracts, the working fluid corresponding to the rod volume flows in and out of the tank 3, and the free piston 6 is displaced to change the capacity of the tank 3.

The tank 3 is provided with a spring 8 for urging the free piston 6 in a direction to compress the working fluid, thereby preventing cavitation in the hydraulic circuit.

A seal ring 7 is interposed on the outer periphery of the free piston 6, and the inside of the tank 3 is sealed by sliding the seal ring 7 on the inner wall surface of the tank 3.

[0012]

However, in the above-mentioned device, the free piston 6 moves in the cylindrical member 9 as the cylinder 1 expands and contracts.
A frictional force acts on the hydraulic power package, and the work of the hydraulic power package is wastefully consumed by the frictional force, thereby lowering the operation efficiency.

In particular, when water or the like having poor lubricity is used as the working fluid, the frictional force generated in the seal ring 7 increases, and the operating efficiency is greatly reduced.

[0014] Even if the seal ring 7 is made of a material or a shape having a small frictional force, the operation efficiency relatively decreases as the operation pressure of the hydraulic power package decreases.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a hydraulic power package having a high operating efficiency with reduced loss of work caused by the flow of a working fluid into and out of a tank. .

[0016]

According to a first aspect of the present invention, the operating direction of a cylinder is switched according to the direction in which the pump discharges the working fluid, and the working fluid corresponding to the rod volume is transferred between the hydraulic circuit and the tank as the cylinder expands and contracts. Applies to hydraulic power packages entering and exiting between.

[0017] A hollow elastic body in a bag shape that defines the tank is provided, and the capacity of the tank is changed by elastic deformation of the hollow elastic body.

According to a second aspect, in the first aspect, a tank is defined by an inner surface of the hollow elastic body, and an outer surface of the hollow elastic body is exposed to the atmosphere.

According to a third aspect, in the first or second aspect, the hollow elastic body has a bellows-like or bladder-like elastic portion.

In a fourth aspect based on any one of the first to third aspects, the hollow elastic body has a spring hardness H.
S is formed of an elastic material of 60 or more.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a cover portion surrounding the hollow elastic body is provided.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, a spring for urging the hollow elastic body in a contraction direction is provided.

[0023]

According to the first aspect of the present invention, the hydraulic power package switches the direction of expansion and contraction of the cylinder by switching the direction of rotation (discharge direction) of the pump.

The working fluid corresponding to the rod volume flows in and out of the tank as the cylinder expands and contracts, and the capacity of the tank changes due to the elastic deformation of the hollow elastic body. Thus, there is no need to provide a sliding member such as a free piston as in the conventional device, and the operating efficiency of the hydraulic power package can be increased.

According to the second invention, the tank is defined by the inner surface of the hollow elastic body, and the outer surface of the hollow elastic body is exposed to the atmosphere, so that the structure of the tank is simplified and the weight is reduced. At the same time, product costs can be reduced.

According to the third aspect, the expansion and contraction portion expands and contracts due to its elastic deformation, and the pressure change in the tank can be reduced.

According to the fourth aspect of the present invention, the hollow elastic body is prevented from drooping largely due to gravity, the hollow elastic body is prevented from being damaged without interfering with surrounding members and the like, and the hydraulic power package is prevented. Work is not wasted.

According to the fifth aspect of the present invention, the hollow elastic body is protected by the cover, so that the hollow elastic body can be prevented from being damaged at the time of assembling or maintaining the hydraulic power package.

According to the sixth aspect, the inside of the tank is pressurized by the elastic restoring force of the spring, and the occurrence of cavitation in the hydraulic circuit can be prevented.

[0030]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a cross section of a tank 3 provided in the hydraulic power package. Components such as a bidirectional pump, a valve, and an electric motor, which constitute the hydraulic power package, are provided together with the tank 3 as a unit.

The hydraulic circuit of the hydraulic power package is configured as shown in FIG. 4, and by switching the rotation direction (discharge direction) of the pump, the expansion / contraction operation direction of the cylinder is switched, and the expansion / contraction operation of the cylinder is performed. Accordingly, the working fluid corresponding to the rod volume flows in and out of the tank 3.

The gist of the present invention is to provide a bag-shaped hollow elastic body 13 defining the tank 3,
The capacity of the tank 3 can be changed by the elastic deformation. The hollow elastic body 13 defines the tank 3 by its inner surface, and its outer surface is exposed to the atmosphere.

In the present embodiment, the hollow elastic body 13 has an elastic portion 13a having a bellows cross section and opening portions 13 at both ends thereof.
b, 13c. One of the openings 13 b is connected to the tubular member 9 via the annular member 14, and the other
c is closed via the lid 15.

The opening 13b of the hollow elastic body 13 is fitted on the outer periphery of the annular member 14, and the annular member 14 is connected to the opening end of the tubular member 9 via the ring 16.

In the present embodiment, an opening 13c is formed at the end of the hollow elastic body 13 as a passage for injecting the working fluid into the tank 3, but instead a passage for injecting the tank 3 into the manifold is provided. It may be provided in the block 5 or the like.

The hollow elastic body 13 has a spring hardness HS.
= 60 or more elastic material (for example, rubber material). Thereby, the working fluid is filled and its central axis O
The rigidity is ensured so that the elastic part 13a does not droop drastically due to gravity even in a state in which.

The bellows-like expansion and contraction portion 13a expands and contracts in the direction of its central axis O with a change in the capacity of the tank 3.

In the present embodiment, the cross section of the elastic portion 13a is formed in a bellows shape, but the cross section may be formed in a bladder shape.

Next, the operation of the embodiment of the present invention configured as described above will be described.

In the hydraulic circuit of the hydraulic power package, as the working fluid corresponding to the rod volume flows in and out of the tank as the cylinder expands and contracts, the bag-shaped hollow elastic body 13 is elastically deformed and the capacity of the tank 3 changes. Can be In this way, the change in the capacity of the tank 3 is absorbed by the elastic deformation of the hollow elastic body 13, so that there is no need to provide a sliding member such as a free piston as in the conventional device, and the frictional force of the free piston or the like causes the hydraulic power package The amount of work is not wasted and the operation efficiency can be increased. Even when water or the like having poor lubricity is used as the working fluid, the working efficiency does not significantly decrease.

The bellows-like expansion and contraction portion 13a expands and contracts due to its elastic deformation, so that the pressure change in the tank can be reduced.

The hollow elastic body 13 defines the tank 3 by its inner surface, and the outer surface thereof is exposed to the atmosphere. The structure can be simplified to reduce the weight, and the cost of the product can be reduced.

Next, in another embodiment shown in FIG. 2, a cover 9c surrounding a hollow elastic body 13 is formed in a tubular member 9. The cover 9c is formed integrally with a tank 9d that defines the tank 3 of the tubular member 9. Therefore, the opening 13 c of the hollow elastic body 13 is connected to the middle of the tubular member 9 via the annular member 14.

In this case, the hollow elastic body 13 is
Thus, the hollow elastic body 13 can be prevented from being damaged at the time of assembling or maintaining the hydraulic power package.

The hollow elastic body 13 is made of an elastic material having a hardness of spring hardness HS = 60 or more, and has rigidity so as to have a gap with respect to the cover 9c against gravity. Thus, the hollow elastic body 13 can be prevented from slidingly contacting the cover 9c and being damaged without contacting the cover 9c.

Next, another embodiment shown in FIG. 3 is provided with a coil spring 17 for urging the hollow elastic body 13 in a contraction direction.

The coil spring 17 is interposed inside the hollow elastic body 13, one end of which is connected to the opening 13 c of the hollow elastic body 13 via the locking member 18, and the other end (not shown)
Is connected to the proximal end side of the tubular member 9 and is interposed in a state of being pulled between them.

In this case, cavitation can be prevented from occurring in the hydraulic circuit by pressurizing the tank 3 with the elastic restoring force of the coil spring 17.

It is apparent that the present invention is not limited to the above-described embodiment, and that various changes can be made within the scope of the technical concept.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a tank according to another embodiment.

FIG. 3 is a sectional view of a tank showing another embodiment.

FIG. 4 is a hydraulic circuit diagram of a hydraulic power package showing a conventional example.

FIG. 5 is a plan view of the hydraulic power package.

FIG. 6 is a sectional view of the same tank.

[Explanation of symbols]

 3 Tank 9 Cylindrical Member 9c Cover 13 Hollow Elastic Body 13a Elastic Section 17 Coil Spring

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H081 AA03 BB01 CC28 HH10 3H086 AA29 AB02 AC02 AE05 AE11 AE21

Claims (6)

[Claims] 1. A hydraulic power package in which a working direction of a cylinder is switched according to a direction in which a bidirectional pump discharges a working fluid, and a working fluid corresponding to a rod volume flows in and out of the tank as the cylinder expands and contracts. A hydraulic power package, comprising: a bag-shaped hollow elastic body defining the tank; wherein the capacity of the tank is changed by elastic deformation of the hollow elastic body. 2. The hydraulic power package according to claim 1, wherein the tank is defined by an inner surface of the hollow elastic body, and an outer surface of the hollow elastic body is exposed to the atmosphere. 3. The hydraulic power package according to claim 1, wherein the hollow elastic body has a bellows-like or bladder-like elastic portion. 4. The hollow elastic body has a spring hardness HS.
The hydraulic power package according to any one of claims 1 to 3, wherein the hydraulic power package is formed of 60 or more elastic materials. 5. The hydraulic power package according to claim 1, further comprising a cover surrounding the hollow elastic body. 6. The hydraulic power package according to claim 1, further comprising a spring for urging the hollow elastic body in a contraction direction.