JP2502900Y2 - Multi-piston pump / motor - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a hydraulic pump used for a hydraulic excavator or the like, and more particularly to a piston pump / motor that is a multiple pump but is compact and excellent in self-priming property. .

[Prior Art] As a piston pump of this type, for example, Japanese Patent Laid-Open No. 52-
35304 is known.

That is, in the piston pump / motor disclosed in this publication, the passages from the plurality of cylinder holes to the port plate are divided into two groups, and these passages are independently communicated with each other to the port plate. Is configured to have a function similar to that of the dual pump.

[Problems to be solved by the invention] However, when the piston pump / motor configured as described above is put to practical use, the two discharge ports provided in the port plate are provided on the concentric circle, both inside and outside. Therefore, as compared with a normal pump provided with one discharge port, the high pressure region on the sliding surface between the cylinder and the port plate is wider in the former, and as a result, the hydraulic pressure between the cylinder and the port plate is increased. The separating force may exceed the force that presses the cylinder against the port plate, and the cylinder may separate from the port plate. In order to avoid this, the discharge port opening area of the port plate and the passage area of the cylinder hole communicating with this port during rotation must be reduced. As a result, the suction resistance from the port plate to the cylinder hole in the suction stroke of each piston increases, cavitation easily occurs, and high speed operation cannot be performed.

Therefore, an object of the present invention is to form a cover in contact with the back surface of the port plate, as compared with a conventional multiple pump that discharges pressure oil discharged from a plurality of pistons in one cylinder block to two independent ports. Insert the stepped bush in the stepped bush hole so that it can slide axially,
By pressing this bush to the port plate side by the action of hydraulic pressure, it is possible to expand the passage area from the cylinder hole to the port plate, and it is possible to greatly improve the self-priming property of the pump. To provide.

[Means for Solving the Problems] In order to achieve the above object, pistons are axially slidably fitted into a plurality of cylinder holes formed in a cylinder block, and an end surface of the cylinder block is attached to a cover. Is positioned and is slidably and liquid-tightly pressed against a port plate that is movable in the axial direction of the cylinder block. Further, the end surface of the cylinder block has a different radius from each of the cylinder holes toward the port plate. Opening a plurality of flow passages on the concentric circles, a plurality of ports having different radii corresponding to these flow passages and separated from each other so as to communicate with the plurality of flow passages are opened on the concentric circles of the port plate, In a multi-piston pump / motor configured so that fluid can be discharged independently from these multiple ports, the cylinder block and shuffle Are integrally formed, and a plurality of stepped holes corresponding to any of a plurality of ports formed in the port plate are formed on the port plate side of the cover, and a stepped bush is axially formed in these stepped holes. It is characterized in that it is slidably inserted and pressure oils of the corresponding port and other ports are introduced into the respective stepped portions of the bush.

In this case, the bush has a hollow interior to correspond to any of a plurality of ports formed on the port plate, and the hollow portion of the bush is disposed on the discharge side (pump side) formed on the cover. Or the suction side (in the case of a motor), the bush is arranged at each stepped portion of the bush at each of the discharge side port or the suction side port and at other positions with different radii. It is preferable that the port pressures are introduced so that the end faces of the port plates are liquid-tightly pressed against the end faces of the bushes by the action of the pressures.

[Operation] The multi-piston pump / motor according to the present invention is different from the conventional multi-pump in which one cylinder block discharges pressure oil discharged from a plurality of pistons to two independent ports, as compared with a conventional multi-pump. The stepped bush is inserted axially slidably into the stepped bush hole formed in the cover that is in contact with, and the bush is pressed toward the port plate by hydraulic pressure. The area can be expanded, and the self-priming property of the pump can be greatly improved.

[Embodiment] An embodiment of a multi-piston pump / motor according to the present invention will be described in detail below with reference to the accompanying drawings.

1 is an overall sectional view of a multiple piston pump / motor according to the present invention, FIG. 2 is an AA sectional view of FIG. 1, FIG. 3 is a BOC sectional view of FIG. 1 is a sectional view taken along the line EE of FIG. 1, FIG. 5 is a sectional view taken along the line B-O-D of FIG. 2, and FIG. 6 is a sectional view taken along the line C-O-D of FIG.

In FIG. 1, reference numeral 10 indicates a shaft, and the shaft 10 is integrally formed with a cylinder block 12.

Plural cylinder holes 14 are bored on the concentric circles of the cylinder block 12, and the pistons are placed in the respective cylinder holes 14.
16 is slidably inserted in the axial direction. A port plate 20 attached to a cover 18 is liquid-tightly pressed against the end surface of the cylinder block 12.

As shown in FIG. 2, the port plate 20 has two arc-shaped discharge ports on concentric circles with different radii.
22a and 22b are formed adjacent to each other, and an arc-shaped common suction port 24 having a width including these two discharge ports 22a and 22b is provided.

Then, as shown in FIG. 4, the cylinder block 12
There are multiple cylinder holes 14 at the end of the
Two discharge ports 22a, 22b formed in 20 and a plurality of flow passages 26a, 26b, 26c and 28a, 28b, 28c communicating with the suction port 24 are alternately formed on concentric circles with different radii. ing.

More specifically, each discharge port 22a arranged inside and outside,
The groove 22b is composed of grooves 23b and 23c having a length extending between the flow passages of the cylinder holes 14 adjacent to each other, and flow holes 23a and 23d formed in a part of these grooves.

That is, the flow holes 23a and 23d are alternately arranged so as to communicate with the adjacent cylinder holes 14.

Further, as shown in FIG. 3, two stepped holes 30a, 30b are formed adjacently on the port plate 20 side of the cover 18, and hollow holes 32a, 32b are formed in these stepped holes 30a, 30b. The stepped bushes 34a, 34b are press-fitted so as to be slidable in the axial direction.
Two discharge ports 36a, 36b are formed in the cover 18, and the discharge ports 36a, 36b are respectively formed with the stepped holes 30a, 3b.
0b and the hollow hole 32 of the stepped bushes 34a, 34b.
It corresponds to a and 32b respectively.

Further, the pressure oil of the discharge port 36a and the other port 36b corresponding thereto is introduced into the oil chamber 40a of the one stepped bush 34a, and the oil pressure 40b of the other stepped bush 34b corresponds to this. It is configured to introduce pressure oil from the discharge port 36b and the other port 36a. And each of the stepped holes 30
Stepped bushes 3 that are inserted into the bottoms of a and 30b and these stepped holes 3
Elastic bodies 42a, 42b (for example, disc springs) are interposed between one end faces of the 4a, 34b, and liquid-tightly presses the joint faces of the end faces of the stepped bushes 34a, 34b and the port plate 20. .

 Next, the operation of this multiple pump will be described.

That is, when the shaft 10 is rotated by an external drive source (not shown), the plurality of pistons 16 reciprocate in the axial direction in the cylinder hole 14 to perform a pumping action.

Due to this reciprocating motion, among the two discharge ports formed in the port plate 20, for the inner small diameter discharge port 22a, a plurality of flow passages 26a of each cylinder 14 shown in FIG.
26b and 26c are sequentially opened by the rotation of the cylinder block 12, and the pressure oil in the cylinder 14 is the stepped bush 34 shown in FIG.
It is discharged from the discharge port 36a to the outside through the hollow hole 32a of a. Further, a plurality of flow passages 28a, 28b, 28c of each cylinder 14 are sequentially opened to the large diameter discharge port 22b on the outer side, and the pressure oil in the cylinder hole 14 is hollow in the stepped bush 34b shown in FIG. It is discharged from the discharge port 36b to the outside through the hole 32b.

Here, for example, the discharge port shown in FIG. 4 and FIG.
If high pressure acts on 36a, this pressure acts on the area of the diameter D ₂ of the stepped bush 34a in the small diameter discharge port 22a, and part of this pressure is on the other stepped bush 34b. Since it is also guided to the oil chamber 40b, the diameter difference
Acting on the area of the D ₄ -D _3.

The resultant pressure of the discharge port 36a is the port plate 20.
By pressing against the end surface of the cylinder block 12 to overcome the force generated in the discharge port 22a and causing the port plate 20 to separate from the cylinder end surface.
It is possible to prevent pressure oil from leaking between the end surface of the port plate 20 and the port plate 20 contacting this surface.

In this case, if the flow passages 26a, 26b, 26c are enlarged, the suction resistance to the cylinder hole 14 is reduced on the suction side and the cavitation resistance performance of the pump is improved, but when the flow passage is on the discharge side, the cylinder block The separation force by the pressure oil between the contact surface between the end face 12 and the port plate 20 increases.

However, in the embodiment of the present invention, the stepped bush is used.
Diameter D _{2 of} 34a and diameter difference D ₄ of other bush 34b adjacent to each other.
Since the larger the -D _3, it is possible to offset the separation force.

The same applies to the case where high pressure oil acts on the discharge port 36b as in the above, and the detailed description thereof will be omitted.

Furthermore, when pressure oil acts on both discharge ports 36a and 36b, the force pressing the port plate 20 to the end surface of the cylinder block 12 is the diameter D ₂ of the stepped bush 34a and the diameter difference D _{4 of the} other stepped bush 34b. discharge port 36a in each area of -D ₃
The pressure acting on the discharge port 36b is applied to each area of the diameter D ₃ of the stepped bush 34b and the diameter difference D ₁ -D ₂ of the other stepped bush 34a. Even if a separation force due to pressure oil is generated in each of the discharge ports 22a, 22b, the resultant force causes the port plate 20 to press the end surface of the cylinder block 12, so that the pressure oil can be prevented from leaking from this contact surface. it can.

Incidentally, in the above-mentioned embodiment, the multi-piston pump is explained, but it goes without saying that the present invention can be used as a motor.

[Advantages of the Invention] As is apparent from the above-described embodiments, the multi-piston pump / motor according to the present invention has the cylinder and the shaft integrally formed, and is formed on the port plate side of the cover. A plurality of stepped holes corresponding to any of a plurality of ports are formed, and stepped bushes are inserted into these stepped holes so as to be slidable in the axial direction, and corresponding to each stepped portion of the bush. It is possible to increase the passage area from the cylinder hole to the port plate by configuring the pressure of each port to be introduced and the pressure of other ports respectively, greatly improving the self-priming property of the pump and enabling high-speed operation. At the same time, it has an excellent effect that the structure can be formed compactly.

Although the preferred embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to the embodiment of the present invention and various design changes can be made without departing from the spirit of the present invention.

[Brief description of drawings]

1 is an overall sectional view of a multiple piston pump / motor according to the present invention, FIG. 2 is an AA sectional view of FIG. 1, FIG. 3 is a BOC sectional view of FIG. 1 is a sectional view taken along the line EE of FIG. 1, FIG. 5 is a sectional view taken along the line B-O-D of FIG. 2, and FIG. 6 is a sectional view taken along the line C-O-D of FIG. 10 …… Shaft 12 …… Cylinder block 14 …… Cylinder hole, 16 …… Piston 18 …… Cover, 20 …… Port plate 22a, 22b …… Discharge port, 23a, 23d …… Flow hole 23b, 23c …… Groove , 24 …… Suction port 26a, 26b, 26c, 28a, 28b, 28c …… Flow passage 30a, 30b …… Stepped hole, 32a, 32b …… Hollow hole 34a, 34b …… Stepped bush 36a, 36b …… Discharge port 40a, 40b …… oil chamber, 42a, 42b …… elastic body

Claims (2)

(57) [Scope of utility model registration request] 1. A piston is slidably fitted in each of a plurality of cylinder holes formed in a cylinder block, and an end surface of the cylinder block is positioned by a cover to move in the axial direction of the cylinder block. A fluid port is slidably pressed against a free port plate, and a plurality of flow passages are formed on the end surface of the cylinder block on concentric circles having different radii from the cylinder holes toward the port plate. In order to communicate with the plurality of flow passages, a plurality of ports having different radii corresponding to these flow passages and separated from each other are opened on the concentric circles of the port plate,
In a multi-piston pump / motor configured to independently discharge fluid from these plural ports, a cylinder block and a shaft are integrally configured, and the port plate is formed on the port plate side of the cover. A plurality of stepped holes corresponding to any of a plurality of ports are formed, and stepped bushes are inserted into these stepped holes so as to be slidable in the axial direction, and corresponding to each stepped portion of the bush. A multi-piston pump / motor, characterized in that it is configured to introduce the pressure oil of each port and the other port respectively. 2. The inside of the bush is made hollow so as to correspond to any of a plurality of ports formed in the port plate, and the hollow portion of the bush is formed on the discharge side formed in the cover. (For pump) or suction side (for motor) port, corresponding to each stepped portion of the bush at the discharge side or suction side port and other positions with different radii 2. A multi-piston pump / motor according to claim 1, wherein said multi-piston pump motor is constructed so as to introduce the pressure of each port, and the end face of said port plate is liquid-tightly pressed against the end face of said bush by the action of this pressure.