JPH11236869A - Hydraulic source device for preventing surge pressure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic source device for preventing a surge pressure to prevent the generation of a surge pressure. SOLUTION: A cam plate is arranged on the outside of a piston radially arranged at a cylinder block, and working oil is fed to a hydraulic motor 50, generating relative rotation between a cylinder block and a cam plate, from a hydraulic pump 82 through a long hose 70a by a piston on which operation of feeding working oil is exerted. In this case, the suction side of the hydraulic motor 50 and the discharge side of the hydraulic motor 50 are interconnected through a pressure reduction valve 1. Further, a relief valve 86 for a charge pressure to interconneot a tank 84 and the discharge side of the hydraulic motor 50 is provided. The secondary pressure of the pressure reduction valve 1 is set to a value lower than a charge pressure generated by the relief valve 86 for a charge pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surge pressure preventing hydraulic power source device for preventing generation of a surge pressure in a hydraulic motor.

[0002]

2. Description of the Related Art As shown in FIG. 4, a cam plate type hydraulic motor 50 has conventionally been used. The hydraulic motor 50 has a plurality of sliding holes 52 in a cylinder block 51.
Are formed radially, and a piston 54 is slidably inserted into the sliding hole 52. A working chamber 55 is formed by each piston 54 and the sliding hole 52.

[0003] A cam plate 56 is provided outside the piston 54.
Are disposed, and a wavy cam surface 58 is formed on the inner periphery of the cam plate 56. Hereinafter, each piston 5
4 and the working chamber 55 are denoted by reference numerals a to j to distinguish each piston 54 and the working chamber 55.

The pistons 54a to 54j are configured to contact the cam surface 58 via rollers 60, and a rotary valve 62 is coaxially inserted into the cylinder block 51. The rotary valve 62 selectively communicates the working chambers 55a to 55j with the discharge side or the suction side.

When the piston 54a receives the action of the supplied hydraulic oil, the acting force of the piston 54a acts on the cam plate 56 via the roller 60 and the cam surface 58. Therefore, relative rotation occurs between the cam plate 56 and the cylinder block 51. In the present embodiment, the cylinder block 51 rotates. Also, the pistons 54c, 54f,
The operating oil pressure also acts on 54h to similarly generate a rotational force on the cylinder block 51.

On the other hand, the pistons 54e, 54 at the top dead center
In j, the working chambers 55e and 55j are shut off by the rotary valve 62, and the other working chambers 55b, 55d, 55g and 55i are communicated by the rotary valve 62 to the low pressure side of the tank or the like, and the hydraulic oil is discharged. A drain chamber 64 is formed between the cam plate 56 and the cylinder block 51, and hydraulic oil leaked from between the pistons 54 a to 54 j and the sliding holes 52 flows into the drain chamber 64 once.

As shown in FIG. 5, the hydraulic motor 50 is connected to a switching valve 74 via a pair of supply channels 70 and 72, and a main channel 76 and a return channel 78 are connected to the switching valve 74. Have been. The switching valve 74 connects the one supply flow path 70 with the main flow path 76 and connects the other supply flow path 72 and the return flow path 78 with each other.
0, 72, the stop position 74b, one supply flow path 7
0 and the return flow path 78 and the other supply flow path 7
2 and a main flow path 76.

The main flow path 76 is connected to the discharge side of a hydraulic pump 82 driven by a motor 80. The hydraulic pump 82 sucks hydraulic oil from a tank 84 and discharges it to the main flow path 76. The return flow path 78 communicates with a tank 84, and a charge pressure relief valve 86 is interposed in the return flow path 78.

[0009] Main flow path 76 and charge pressure relief valve 86
The return flow path 78 upstream of the flow path is connected via a relief valve 88. Both supply passages 7 near the hydraulic motor 50
The charge flow paths 94 and 0 are connected to charge flow paths 94 through check valves 90 and 92, respectively, which allow the flow into the supply flow paths 70 and 72, respectively.
And one end of the charge flow path 94 is connected to a return flow path 78 upstream of the charge pressure relief valve 86. The hydraulic motor 50 and the tank 84 are connected by a drain passage 96, and the drain passage 96 and the drain chamber 64 of the hydraulic motor 50 are in communication.

When the hydraulic motor 50 is used as a digging tool of a construction machine, the digging tool provided with the hydraulic motor 50 is deep underground, whereas the switching valve 74 is provided on the construction machine body. Accordingly, the hydraulic motor 50 and the switching valve 74 are located at a distance from each other, and some of the supply passages 70 and 72, the charge passage 94, and the drain passage 96 have long hoses 70a, 72a, 94a and 96a are used.

[0011]

However, in such a conventional device, for example, the switching valve 74 is moved to the normal rotation position 74.
a, the load may increase and the rotation of the hydraulic motor 50 may stop when the hydraulic motor 50 is rotating forward. In this case, as shown in FIG. 6, the suction side pressure of the hydraulic motor 50 gradually increases due to the expansion of the long hose 70a and the like, whereas the discharge side pressure of the hydraulic motor 50 stops sharply because the rotation stops. To decline.

Thus, the working chambers 55b, 55d, 55
The pressure in the g and 55i is lower than the pressure in the drain chamber 64, and the pistons 54b, 54d, 54g and 54i receive the operating oil pressure of the drain chamber 64, and the roller 60 slides in the direction away from the cam surface 58. . When the pressure on the suction side increases and the relief valve 88 operates, the charge pressure is introduced to the discharge side of the hydraulic motor 50 via the return flow path 78, the charge flow path 94, the check valve 92, and the supply flow path 72, Working chamber 55
b, 55d, 55g, and 55i increase in pressure. Therefore, since the pistons 54b, 54d, 54g, and 54i slide toward the cam surface 58, the pressure in the drain chamber 64 rises instantaneously and a surge pressure is generated.

In such a state, the switching valve 7
4 is switched to the reverse rotation position 74c, the action chamber 55
High-pressure hydraulic oil is supplied to b, 55d, 55g, and 55i, and the pistons 54b, 54d, 54g, and 54i slide toward the cam surface 58. As a result, there is a problem that the pressure in the drain chamber 64 suddenly increases and a surge pressure is generated, which may damage the bearing seal and the like.

An object of the present invention is to provide a surge pressure preventing hydraulic power source device that prevents generation of surge pressure.

[0015]

In order to achieve the above object, the present invention takes the following means to solve the problem. That is, a cam plate is arranged outside the piston radially arranged on the cylinder block, and the piston receiving the action of the supplied hydraulic oil causes relative rotation between the cylinder block and the cam plate. In a hydraulic power source device for supplying the hydraulic oil to a hydraulic motor, a surge pressure preventing hydraulic power source device is characterized in that a suction side of the hydraulic motor and a discharge side of the hydraulic motor are connected via a pressure reducing valve. is there.

It is preferable that a charge pressure relief valve for connecting the low pressure side and the discharge side of the hydraulic motor be provided, and that the secondary pressure of the pressure reducing valve be lower than the charge pressure by the charge pressure relief valve. Further, the hydraulic oil may be supplied to the hydraulic motor via a long hose.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same members as those in FIGS. 4 and 5 described above are denoted by the same reference numerals, and detailed description is omitted. As shown in FIG. 1, the primary sides of the pressure reducing valve 1 are connected to both supply passages 70 and 72 in the vicinity of the hydraulic motor 50 via check valves 2 and 4 that allow the pressure to flow into the pressure reducing valve 1. A check valve 6 that allows outflow from the pressure reducing valve 1 is connected to the secondary side of the pressure reducing valve 1, and the check valve 6 is connected to the two supply flow paths 70 and 72 via the check valves 90 and 92 described above. It is connected.

The pressure reducing valve 1 is connected to supply passages 70, 72 on the hydraulic motor 50 side with respect to the long hoses 70a, 72a.
At a location as close to the hydraulic motor 50 as possible,
Preferably, it is connected to 72. When the hydraulic motor 50 rotates forward, the suction side of the hydraulic motor 50 (the supply flow path 7
0) and the discharge side (supply flow path 72) of the hydraulic motor 50
They are connected via a check valve 2, a pressure reducing valve 1, and a check valve 92, and in the case of reverse rotation, the suction side (supply flow path 72) of the hydraulic motor 50 and the discharge side (supply flow path 7) of the hydraulic motor 50
0) are connected via the check valve 4, the pressure reducing valve 1, and the check valve 90. In addition, pressure reducing valve 1
Are set to be lower than the charge pressure P1 set by the charge pressure relief valve 86, respectively.

Next, the operation of the hydraulic pressure source device for preventing surge pressure according to the present embodiment will be described. First, the motor 8
When the hydraulic pump 82 is driven by 0, high-pressure hydraulic oil is supplied to the main flow path 76. Switching valve 74 is in normal rotation position 74a
When the operation mode is switched to, hydraulic oil is supplied to the hydraulic motor 50 through the main flow path 76, the switching valve 74, and the supply flow path 70, and the supply flow path 72, the switching valve 74, the return flow path 78, and the charge pressure relief valve 86 From the hydraulic motor 50 to the tank 84
And the hydraulic motor 50 is rotated forward.

At this time, the upstream side of the return passage 78 is maintained at the charge pressure P1 or higher by the charge pressure relief valve 86. Therefore, the action chambers 55b, 55d,
55g and 55j are maintained at the charge pressure P1 or higher, and the pistons 54b, 54d, 54g and 54i are pressed against the cam surface 58 via the rollers 60 so that the rollers 60 do not separate from the cam surface 58.

On the other hand, hydraulic oil due to a leak in the hydraulic motor 50 is returned from the drain chamber 64 to the tank 84 via the drain passage 96. The charge pressure relief valve 86 is set so that the charge pressure P1 is higher than the drain pressure PD of the drain chamber 64 at this time.

When the switching valve 74 is switched to the reverse rotation position 74c, the main flow path 76, the switching valve 74, the supply flow path 72
Hydraulic oil is supplied to the hydraulic motor 50 through the supply passage 70, the switching valve 74, the return passage 78,
The hydraulic oil is discharged to the tank 84 via the charge pressure relief valve 86, and the hydraulic motor 50 is rotated in the reverse direction. At this time, similarly to the above, the charge pressure relief valve 86
As a result, the roller 60 is not separated from the cam surface 58.

For example, when the switching valve 74 is in the normal rotation position 7
4a, when the load on the hydraulic motor 50 increases and the rotation of the hydraulic motor 50 stops, FIG.
As shown in FIG. 7, the supply hydraulic pressure to the hydraulic motor 50 via the supply flow path 70 gradually increases. Further, since the rotation stops, the pressures in the action chambers 55b, 55d, 55g, and 55i decrease rapidly. As a result, there is no action force for pressing the roller 60 against the cam surface 58, and the roller 60 is easily separated from the cam surface 58.

On the other hand, the supply flow path 70 is connected to the other supply flow path 72 via the check valve 2, the pressure reducing valve 1, and the check valve 92. To the secondary pressure P2, and the other supply flow path 7
2 is supplied. Therefore, the working oil of the secondary pressure P2 is supplied to the working chambers 55b and 55 of the hydraulic motor 50 through the supply passage 72.
d, 55g, and 55i. Since the supply flow path 70 connecting the suction side and the discharge side of the hydraulic motor 50, the check valve 2, the pressure reducing valve 1, the check valve 92, and the supply flow path 72 are short in length, the secondary pressure P2 acts. Chambers 55b, 55
d, 55g, 55i.

Thus, the working chambers 55b, 55d, 55
g, 55i, and the roller 60 is pressed against the cam surface 58 via the piston 54. When the piston 54 slides, the volume in the drain chamber 64 decreases and the pressure rises. However, the sliding amount of the piston 54 is small, and the change in the surge pressure rise is small. Therefore, the adverse effect on the bearing seal and the like is small.

Thereafter, when the pressure on the suction side further rises and the relief valve 88 is operated, the discharge side of the hydraulic motor 50 passes through the return flow path 78, the charge flow path 94, the check valve 92, and the supply flow path 72. The charging pressure is introduced and the working chamber 5
The pressure of 5b, 55d, 55g, 55i is the charge pressure P1
To rise to.

Next, a surge pressure preventing hydraulic power source device according to a second embodiment different from the above-described embodiment will be described with reference to FIG. As shown in FIG. 2, in the second embodiment,
The charge flow path 94 is connected to the two supply flow paths 70 and 72 via the check valves 10 and 12 on a side closer to the switching valve 74 than the long hoses 70 a and 72 a. This eliminates the need to use a long hose for the charge flow path 94.
Generation of surge pressure is prevented by the pressure reducing valve 1 as described above.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various modes without departing from the gist of the present invention.

[0029]

As described above in detail, the surge pressure preventing hydraulic power source device of the present invention introduces the pressure on the suction side of the hydraulic motor to the discharge side of the hydraulic motor via the pressure reducing valve. This prevents the surge pressure from being generated when the rotation stops due to the increase in the pressure, thereby preventing the bearing seal and the case of the device from being adversely affected.

By setting the secondary pressure lower than the charge pressure, even if a pressure reducing valve is provided, normal use is not affected. Furthermore, when supplying hydraulic oil to the hydraulic motor through a long hose, the introduction of charge pressure is delayed,
Particularly effective.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a surge pressure preventing hydraulic power source device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a surge pressure preventing hydraulic power source device according to a second embodiment.

FIG. 3 is a graph showing a change in pressure in the present embodiment.

FIG. 4 is an enlarged sectional view of a hydraulic motor.

FIG. 5 is a circuit diagram of a conventional hydraulic power source device.

FIG. 6 is a graph showing a conventional pressure change.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pressure reducing valve 2, 4, 10, 12, 90, 92 ... Check valve 50 ... Hydraulic motor 51 ... Cylinder block 54a-54j ... Piston 55a-55j ... Working chamber 56 ... Cam plate 58 ... Cam chamber 64 ... Drain chamber 70 , 72 ... supply flow path 70a, 72a, 94a ... long hose 74 ... switching valve 76 ... main flow path 78 ... return flow path 82 ... hydraulic pump 86 ... charge pressure relief valve 88 ... relief valve 94 ... charge flow path 96 ... drain Channel

Claims (3)

[Claims] 1. A cam plate is arranged outside a piston radially arranged on a cylinder block, and a relative rotation between the cylinder block and the cam plate is performed by the piston which is acted on by supplied hydraulic oil. A hydraulic pressure source device for supplying the hydraulic oil to a hydraulic motor for generating a surge pressure, wherein a suction side of the hydraulic motor and a discharge side of the hydraulic motor are connected via a pressure reducing valve. apparatus. 2. A charge pressure relief valve for connecting a low pressure side and a discharge side of the hydraulic motor, wherein a secondary pressure of the pressure reduction valve is lower than a charge pressure by the charge pressure relief valve. Item 1. A surge pressure preventing hydraulic power source device according to Item 1. 3. The surge pressure preventing hydraulic power source device according to claim 1, wherein the hydraulic oil is supplied to the hydraulic motor via a long hose.