JP2001200782A - Multiple piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for preventing surging in a multiple piston pump. SOLUTION: In the piston pump, land parts 42, 43 for dividing a delivery port into an initiating side delivery port 21, intermediate delivery ports 22, 23, and a final side delivery port 24 around a rotary shaft O as a center are formed in a valve plate 20, and orifices (throttle passages) 51 to 54 for relieving operating fluid pressure in a displacement chamber 7 are opened to the land parts 42, 43.

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 piston pump.

[0002]

2. Description of the Related Art For example, a working machine or a construction machine is equipped with a multiple piston pump having a plurality of independent discharge passages as a hydraulic source, and a plurality of hydraulic devices are driven by one multiple piston pump. It has become.

[0003] As a conventional multiple piston pump, for example, there has been one provided with three discharge passages 71, 72, 73 as shown in FIG.

To explain this, the valve plate 60 has one suction port 64 and three discharge ports 6.
1, 62 and 63 are open. The discharge port 63 is divided with respect to the discharge ports 61 and 62 in the circumferential direction around the rotation axis. The discharge ports 61 and 62 are divided in a radial direction about the rotation axis.

[0005] With the rotation of the cylinder block, the volume chamber between each cylinder and the piston sequentially communicates with the discharge port 63, and then alternately communicates with the discharge port 61 and the discharge port 62. The discharged hydraulic oil is guided to the three hydraulic devices through the discharge passages 71, 72, 73, respectively. Each discharge passage 71, 72, 73
In this case, hydraulic oil flows are generated independently of each other, and the flow rate and pressure of the hydraulic oil can be set individually.

[0006]

In such a conventional multiple piston pump, each volume chamber is moved from the discharge port 63 to the discharge port 61 with the rotation of the cylinder block.
Alternatively, if the pressure is shut off by the valve plate 60 in the process of communicating with the discharge port 62, a surge pressure may be generated in each volume chamber, causing noise and the like.

In order to prevent this, in the piston pump shown in FIG. 7, notches 61a and 62a are formed at one ends of the discharge ports 61 and 62, respectively.
The pressure in the volume chamber is released through the a and 62a.

However, when the notches 61a and 62a are formed in the valve plate 60,
The setting ranges of the flow rate and the pressure of the working oil are narrowed due to the restrictions on the arrangement of 1, 62 and 63.

The present invention has been made in view of the above problems, and has as its object to provide a structure for preventing surging in a multiple piston pump.

[0010]

According to a first aspect of the present invention, there are provided a cylinder block, a plurality of cylinders disposed in parallel to a rotation axis of the cylinder block, a plurality of pistons defining respective volume chambers in each cylinder, and a cylinder block. A swash plate that reciprocates the piston so as to expand and contract the volume chamber of each cylinder with the rotation of the cylinder, and a valve plate that slides the cylinder block,
The present invention is applied to a piston pump having a suction port and a discharge port that are opened in a valve plate, and a cylinder port that connects a volume chamber of each cylinder to the suction port or the discharge port as the cylinder block rotates.

A land portion is formed in the valve plate to divide the discharge port in the circumferential direction around the rotation axis, and a throttle passage for opening the working oil pressure of the volume chamber is opened in the land portion.

According to a second aspect of the present invention, in the first aspect, the discharge port is divided into inner and outer discharge ports located on different radii about the rotation axis, and the inner and outer discharge ports are formed in the cylinder block with the rotation. Forming an inner cylinder port and an outer cylinder port for communicating the port with each volume chamber,
A throttle passage communicating with both the inner cylinder port and the outer cylinder port with the rotation of the cylinder block is formed in the valve plate.

[0013]

In the first aspect of the present invention, the communication between the discharge ports is interrupted by the cylinder ports facing the lands as the cylinder block rotates. At this time, the throttle passage opening to the land portion connects each cylinder port to the tank via the pump case chamber. This prevents the volume chambers from being completely closed by the lands during the discharge stroke, prevents a surge pressure from being generated in each volume chamber, and reduces noise generated by the pump.

In the second aspect of the present invention, the number of throttle passages formed in the valve plate is halved, and the manufacturing cost of the valve plate can be reduced.

[0015]

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

As shown in FIG. 1, a rotary swash plate type piston pump 10 has a cylinder block 3 and a swash plate 4 housed in an internal space formed by a pump case 1 and a port block 2.

The cylinder block 3 is driven to rotate via a shaft 5. One end of the shaft 5 is supported by the port block 2 via the bearing 12, and halfway is supported by the pump case 1 via the bearing 11.
The rotation of the shaft 5 is transmitted from a power source (not shown) to one end of the shaft 5 protruding outside from the pump case 1.

In the cylinder block 3, ten cylinders 6 are arranged in parallel with the rotation axis O (see FIGS. 3 and 4) and at regular intervals on substantially the same circumference centered on the rotation axis O. Are arranged side by side.

A piston 8 is inserted into each cylinder 6, and a volume chamber 7 is defined between them. One end of each piston 8 protrudes from the cylinder block 3 and the swash plate 4
Is supported via a shoe 9 which is in contact with. When the cylinder block 3 rotates, each piston 8 reciprocates with the swash plate 4 to expand and contract the volume chamber 7 of the cylinder 6. That is,
FIG. 3 shows the cylinder block 3
As the piston 8 rotates in the direction indicated by the arrow, the suction stroke for expanding the volume chamber 7 by the piston 8 and the discharge stroke for contracting the volume chamber 7 are repeated.

As shown in FIG. 4, the end faces of the cylinder block 3 have cylinder ports 13, 1 communicating with the respective chambers 7.
4 opens. The cylinder ports 13 and 14 are
Has an oval opening cross section that is curved in an arc with the center as the center.

A valve plate 20 is provided between the pump case 1 and the port block 2 for slidingly contacting the end surface of the cylinder block 3. A suction port 25 and discharge ports 21 to 24 are respectively opened in the valve plate 20, and each cylinder port 13,
The communication of 14 controls the suction and discharge of hydraulic oil into and from each volume chamber 7.

As shown in FIG. 2, one intake port 25 communicating with each volume chamber 7 is opened in the valve plate 20, and one intake port 25 is connected to the port block 2 in the port block 2.
A book suction passage 35 is formed. As the cylinder block 3 rotates, hydraulic oil from a tank (not shown) is supplied from the cylinder port 13 to each of the volume chambers 7 through a pipe (not shown), a suction passage 35 and a suction port 25.

In the port block 2 of the multiple piston pump 10, three discharge passages 30, 32, 33 are formed, and pressurized hydraulic oil discharged from each volume chamber 7 is supplied to each discharge passage 3.
After passing through 0, 32, and 33, they are respectively guided to three hydraulic devices via piping (not shown).

In the valve plate 20, a start-side discharge port 21, intermediate discharge ports 22, 23, and an end-side discharge port 24 are formed by being divided in the circumferential direction around the rotation axis O. The intermediate discharge ports 22 and 23 are arranged between the end side discharge ports 24 so as to sandwich the intermediate discharge ports 22 and 23.

The Y-shaped junction discharge passage 30 has a branch portion 31 connected to the start side discharge port 21 and a branch portion 34 connected to the end side discharge port 24. Hydraulic oil discharged from each volume chamber 7 to the start-side discharge port 21 and the end-side discharge port 24 merges through the merged discharge passage 30,
It is led to the first hydraulic device via a pipe (not shown).

The outer intermediate discharge port 23 and the inner intermediate discharge port 22 have an elliptical opening cross section that is curved in an arc shape about the center axis O, and are divided from each other in the radial direction about the rotation axis O. It is formed.

As shown in FIG. 4, an inner cylinder port 13 which communicates the volume chamber 7 with the inner intermediate discharge port 22 and an outer cylinder port 14 which communicates with the outer intermediate discharge port 23 are respectively opened on the end surface of the cylinder block 3. are doing. The inner cylinder port 13 is the inner intermediate discharge port 2
2 is formed on the same circumference as the outer cylinder port 14.
Are formed on substantially the same circumference as the outer intermediate discharge port 23.

A discharge passage 32 is connected to the inner intermediate discharge port 22. Inside cylinder port 13 compressed in volume chamber 7
Hydraulic oil discharged to the inner intermediate discharge port 22 from the
It is led to the second hydraulic device through the discharge passage 32 and a pipe (not shown).

A discharge passage 33 is connected to the outer intermediate discharge port 23. Outer cylinder port 14 compressed in volume chamber 7
The hydraulic oil discharged from the outer intermediate discharge port 23 is
It is guided to the third hydraulic device through the discharge passage 33 and a pipe (not shown).

The angle ranges θ1a and θ1b in which the cylinder ports 13 and 14 are opened are set smaller than the angle between the cylinders 13 and 14. That is, assuming that the number of cylinders 6 is N (= 10), the setting is made so that the following equations (1) and (2) are satisfied. 0 <θ1a <(360 ° / N) (1) 0 <θ1b <(360 ° / N) (2) As shown in FIG.
And four land portions 41 to 44 extending between ２５25 and ２５25.

Start-side discharge port 21 and intermediate discharge port 2
The angle range θ2a at which the land portion 42 sandwiched between the cylinder ports 2 and 23 expands is formed to be larger than the angle ranges θ1a and θ1b at which the cylinder ports 13 and 14 open. Similarly, the angle range θ2b where the land portion 43 sandwiched between the intermediate discharge ports 22 and 23 and the end side discharge port 24 expands is formed larger than the angle ranges θ1a and θ1b where the cylinder ports 13 and 14 are open. That is, it is set so that the following equations (3) to (6) are satisfied. θ2a ≧ θ1a (3) θ2b ≧ θ1a (4) θ2a ≧ θ1b (5) θ2b ≧ θ1b (6) As a result, the cylinder ports 13, 14 are moved to the start-side discharge ports 21 as the cylinder block 3 rotates. In the process of going to the intermediate discharge ports 22, 23, the air is blocked against the land portion 42, and the ports 21, 22, 23 are sealed. Similarly, with the rotation of the cylinder block 3, the cylinder ports 13, 14 become the intermediate discharge ports 22, 23.
In the process of moving from the
3, and the port 22, 23, 24 is sealed.

The gist of the present invention is that the valve plate 20 has an orifice opening to the land portions 42 and 43 as a throttle passage opening to the land portions 42 and 43 to release the operating oil pressure of each volume chamber 7. 51 to 54 are formed. Each orifice 51-54 is provided in the pump case chamber 29.
And communicate with the tank side to prevent surge pressure from being generated in each volume chamber 7.

The orifice 51 is disposed on the substantially same circumference as the inner cylinder port 13 between the start side discharge port 21 and the intermediate discharge port 22.

The orifice 52 is arranged on the same circumference as the outer cylinder port 14 between the start side discharge port 21 and the intermediate discharge port 23.

The orifice 53 is disposed on the substantially same circumference as the inner cylinder port 13 between the intermediate discharge port 22 and the end discharge port 24.

The orifice 54 is disposed on the substantially same circumference as the outer cylinder port 14 between the intermediate discharge port 23 and the end side discharge port 24.

The orifices 51, 52 are arranged on a line C1 that bisects a land portion 42 sandwiched between the start side discharge port 21 and the intermediate discharge ports 22, 23.

The orifices 53 and 54 are located at the intermediate discharge port 2
The land portion 43 sandwiched between the discharge ports 24 and 23 and the end side discharge port 24 is disposed on a line C2 that bisects the land portion 43.

A notch 25a is formed at one end of the suction port 25 in the valve plate 20. The pressure gradient in the volume chamber 7 becomes smooth via the notch 25a, and the pressure pulsation in the suction passage 35 is reduced.

The swash plate 4 is tiltably attached to the pump case 1 via a support shaft (not shown). By changing the tilt angle of the swash plate 4, the stroke of each piston 8 changes, and the displacement per one rotation of the shaft 5 changes.

A spring 15 is interposed between the swash plate 4 and the pump case 1, and the swash plate 4 is urged by the spring 15 in a direction to maximize the tilt angle.

A hydraulic cylinder 16 for moving the swash plate 4 against the spring 15 is interposed between the swash plate 4 and the pump case 1. The hydraulic cylinder 16 includes a cylinder 17 formed in the pump case 1 and a piston 18 slidably inserted into the cylinder 17, and the oil chamber 1 defined therebetween.
An operating oil pressure is guided to 9 via an oil passage (not shown) formed in the port block 2. As the hydraulic pressure rises, the hydraulic cylinder 16 causes the piston 18 to protrude from the cylinder 17 to reduce the tilt angle of the swash plate 4 and reduce the displacement of the pump per rotation of the shaft 5.

The operation will be described next.

Each rotation of the cylinder block 3 causes each piston 8 to reciprocate in the cylinder 6 one time. In the suction stroke in which the volume chamber 7 of the cylinder 6 expands, hydraulic oil is supplied from the suction port 25 of the valve plate 20 to the cylinder ports 13 and 14.
Through the chamber 7. In the discharge stroke in which the volume chamber 7 of the cylinder 6 contracts, the hydraulic oil is discharged from the volume chamber 7 through the cylinder ports 13 and 14 to the respective discharge ports 21 to 24 of the valve plate 20 in order. Thereby, a flow of hydraulic oil independent of each other occurs in each of the discharge passages 30, 32, and 33, and the flow rate and pressure of hydraulic oil can be individually set.

Since the start-side discharge port 21 and the end-side discharge port 24 are separated from each other in the circumferential direction about the rotation axis O, the start-side discharge port 21 and the end-side discharge port 24 are always different. Since the volume chambers 7 communicate with each other and the hydraulic oil from the plurality of volume chambers 7 is constantly discharged into the merged discharge passage 30, the pressure pulsation of the hydraulic oil discharged from the merged discharge passage 30 can be reduced.

In the intermediate section B of the discharge stroke, the fluctuation range of the flow rate of the hydraulic oil discharged from one volume chamber 7 is the start section A
Alternatively, the discharge passages 32, 3 communicating with the respective volume chambers 7 in the intermediate section B of the discharge stroke because the discharge passages 32, 3
3, the pressure pulsation can be kept small.

As described above, each of the discharge passages 30, 32, 33
, The pressure pulsation in each of the discharge passages 30, 32, and 33 is suppressed to a small extent, the vibration of the hydraulic piping and hydraulic equipment through which these operating oil pressures are guided is suppressed, and noise is reduced. Peel off.

The gist of the present invention is that the orifices 51 to 5 opening to the lands 42 and 43 are provided.
4 releases the operating oil pressure of each volume chamber 7 to the tank side via the pump case chamber 29, so that no surge pressure is generated in each volume chamber 7.

That is, the communication between the discharge ports 21 to 24 is cut off by the cylinder ports 14 facing the lands 42 and 43 as the cylinder block 3 rotates. At this time, the orifices 51 to 54 opening to the lands 42 and 43 connect the respective cylinder ports 14 to the tank via the pump case chamber 29. Thus, in the discharge stroke, each of the volume chambers 7 is connected to the land portions 42 and 4.
3, the pressure gradient in each of the volume chambers 7 is smoothed, a surge pressure is prevented from being generated in each of the volume chambers 7, and the noise generated from the pump is reduced.

Next, another embodiment shown in FIGS. 5 and 6 will be described. The same components as those in the above-described embodiment are denoted by the same reference numerals.

A single orifice 55, 56 is opened in each of the lands 42, 43, and each of the orifices 55, 5 is opened.
6 is formed at a position to communicate with both of the cylinder ports 13 and 14.

As shown in FIG.
When the air passes through the lands 42 and 43, the inner cylinder ports 13 communicate with the orifices 55 and 56, respectively.
The operating oil pressure of each of the volume chambers 7 is released to the tank side via the pump case chamber 29, thereby preventing generation of a surge pressure in each of the volume chambers 7.

As shown in FIG. 6, the outer cylinder port 14
When the air passes through the lands 42 and 43, the inner cylinder ports 13 communicate with the orifices 55 and 56, respectively.
The operating oil pressure of each of the volume chambers 7 is released to the tank side via the pump case chamber 29, thereby preventing generation of a surge pressure in each of the volume chambers 7.

In this case, the number of orifices 55 and 56 formed in the valve plate 20 is reduced by half compared with the embodiment shown in FIG. 2, and the manufacturing cost of the valve plate 20 can be reduced.

As another embodiment, a configuration may be adopted in which the throttle passage opening to the land portion communicates with the discharge passage to release the pressure in each volume chamber.

The present invention is not limited to the swash plate type piston pump,
Applicable to oblique shaft type piston pumps. It is apparent that various modifications can be made within the scope of the technical concept.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multiple piston pump showing an embodiment of the present invention.

FIG. 2 is a front view of the valve plate and the port block.

FIG. 3 is a front view of the valve plate.

FIG. 4 is a front view of a cylinder block and the like.

FIG. 5 is a front view of a valve plate showing another embodiment.

FIG. 6 is a front view of the valve plate.

FIG. 7 is a front view of a valve plate and the like showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump case 2 Port block 3 Cylinder block 4 Swash plate 5 Shaft 6 Cylinder 7 Volume chamber 8 Piston 13 Cylinder port 20 Valve plate 21 Start side discharge port 22 Outside middle discharge port 23 Inside middle discharge port 24 End side discharge port 25 Suction port 29 Pump case chamber 42 Land section 43 Land section 51 to 56 Orifice (throttle passage)

Claims (2)

[Claims] A plurality of cylinders disposed in a cylinder block in parallel with a rotation axis thereof; a plurality of pistons defining respective volume chambers in the respective cylinders; and a plurality of cylinders associated with rotation of the cylinder block. A swash plate for reciprocating the piston so as to expand and contract the volume chamber of the cylinder, a valve plate for slidingly contacting the cylinder block, and a suction port and a discharge port opened to the valve plate. A piston pump for connecting each of the volume chambers to the suction port or the discharge port, wherein a land portion that divides the discharge port in a circumferential direction around a rotation axis is formed on the valve plate; A throttle passage for opening the working oil pressure of the volume chamber. Pump. 2. The discharge port is divided into inner and outer discharge ports located on different radii about a rotation axis, and the inner and outer discharge ports communicate with the respective volume chambers as the cylinder block rotates. An inner cylinder port and an outer cylinder port to be formed are formed, and the throttle passage communicating with both the inner cylinder port and the outer cylinder port with the rotation of the cylinder block is formed in the valve plate. Item 4. The multiple piston pump according to Item 1.