JPH07243402A - Hydraulic pressure gradually varying mechanism - Google Patents

Abstract

PURPOSE:To constitute a hydraulic pressure gradually varying mechanism as a single kind of assembled part basically thereby putting this mechanism advantageous in view of parts mamufacture and parts management by selectively setting the gradually varying property by a throttle member being an annexed part. CONSTITUTION:In a hydraulic pressure gradually varying mechanism A, which is installed in the oil supply and exhaust passage connecting a hydraulic motor capable of normal and reverse revolution to a control valve for this hydraulic actuator, a relief valve 7, which discharges oil when the oil pressure inside the oil supply and discharge passage reaches a specified value or over, and a cushion part 15, which is energized to recover an oil chamber 10 to specified small volume by the piston 9 energized by a spring, are incorporated in the casing 16, and also herein a connection oil passage 13, which connects and oil passage 15 on pressure supply side before the relief valve 7 with the oil chamber 10, is made. Together with it, a throttle member 21, where an orifice 20 reducing the sectional area of the connection oil passage 13 is made, is screwed in the connection oil passage 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shockless technique for mitigating shocks at the time of starting or stopping a hydraulic actuator such as a hydraulic motor for running a backhoe or a cylinder for lifting arms of a wheel loader.

[0002]

2. Description of the Related Art A conventional example of the hydraulic pressure grading mechanism and an operating circuit using the same is shown in FIGS. That is, the hydraulic motor 1 (corresponding to a hydraulic actuator) and the control valve 2
Is connected by a pair of oil supply and drain passages 3 and 4, and a hydraulic circuit capable of rotating the hydraulic motor 1 in the forward and reverse directions by the supply and discharge operation of the hydraulic oil by the switching operation of the control valve 2 is constituted. A is
It is equipped with being connected to the pair of oil supply / drain passages 3 and 4.

The hydraulic pressure grading mechanism A includes a pair of relief valves 7 and 8 which discharge oil when the hydraulic pressure in the oil supply and discharge passages 3 and 4 exceeds a predetermined value.
And a cushion portion 15 in which the volumes of the oil chambers 10 and 11 are returned and urged to the reduction side (predetermined volume) by the piston 9 urged by the pair of springs 12 and 12, and the pressure supply side in the relief valves 7 and 8. Each of the connection oil passages 13 and 14 that communicates the oil passages 5 and 6 and the oil chambers 10 and 11 is configured to be installed inside the valve casing 16.

In the state shown in FIG. 1, the control valve 2 is moved to the neutral position N.
When the control valve 2 is operated to the right rotation position R from this state, the hydraulic oil is supplied from the control valve 2 to the hydraulic motor 1 through the oil supply / exhaust passage 3 and the hydraulic pressure is increased. The motor 1 starts rotating to the right. At this time, the hydraulic oil is supplied to the hydraulic motor 1 and at the same time, the hydraulic oil from the control valve 2 is also supplied to the one oil chamber 10 of the cushion portion 15 via the supply / discharge oil passage 3 and the connection oil passage 13. Then, the piston 9 moves to the left side of the drawing in FIG.
The spring 12 is compressed.

That is, when the hydraulic motor 1 starts to rotate, the hydraulic oil for the hydraulic motor 1 is temporarily used for compressing the spring 12 of the cushion portion 15 to prevent a rapid increase in pressure. Due to the gradual increase action, the hydraulic motor 1
However, it can start rotating smoothly with less shock.

[0006]

In the shockless structure described above, the operating characteristic of the gradual change mechanism A is changed according to the size of the hydraulic actuator, which differs depending on the model and specifications. As shown in FIG. 3, the required shockless characteristics were revealed by appropriately setting the cross-sectional areas of the communication holes S formed in the valve bodies 7A and 8A of the relief valves 7 and 8.

However, in this means, if the diameter of the communication hole S differs depending on the model and specifications, the valve bodies 7A, 8
There was a disadvantage that the management of the parts would be difficult, and there was still room for improvement. An object of the present invention is to eliminate the above-mentioned disadvantages by enabling the valve body of the relief valve to be formed of the same component while allowing the gradual change characteristic to be selectively set by the throttle.

[0008]

In order to achieve the above object, the present invention relates to a hydraulic pressure grading mechanism connected to a hydraulic pressure actuator and a supply / discharge oil passage connecting a control valve for the hydraulic actuator. A relief valve that discharges oil when the oil pressure in the oil passage exceeds a predetermined level, a cushion part that urges the volume of the oil chamber to return to a reduction side by a spring-biased piston, and a pressure supply side oil passage and oil in the relief valve. Each of the connection oil passages communicating with the chamber is installed in the valve casing, and the connection oil passages are equipped with a throttle member having an orifice formed to reduce the cross-sectional area of the connection oil passages. It is characterized by being configured.

[0009]

Operation will be described with reference to FIG. 2. Due to the orifice 20 of the throttle member 21 provided in the connection oil passage 13 that connects the oil chamber 10 and the pressure supply side oil passage 5 of the relief valve 7, the gradual change characteristic is obtained. Since it is decided, the valve body 7 of the relief valve 7
The communication hole S formed in A may be formed in a large size with a sufficient cross-sectional area. In short, in order to set different shockless characteristics, only the diaphragm member 21, which is a small component, needs to be changed, and it is not necessary to change the valve body 7A. Therefore, it is easier to process and the space for storing the parts can be saved by changing the throttle members, which are extremely small parts, than by changing the valve bodies, which are relatively large parts.

[0010]

As a result, basically, the hydraulic gradual change mechanism can be constructed as a single type of assy part by the structural ingenuity for selectively setting the gradual change characteristic by the throttle member which is an attached part. It was possible to provide it in an advantageous state.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an operation circuit structure of a hydraulic motor 1 (double-acting hydraulic actuator) that drives a crawler traveling device of a small backhoe in the forward and reverse directions. Hydraulic motors 1 and 3
A position switching type control valve 2 is connected by a pair of oil supply and drain passages 3 and 4, and hydraulic oil from a hydraulic pump (not shown) is supplied to and discharged from the hydraulic motor 1 by switching the control valve 2. The hydraulic motor 1 can be rotated in the forward and reverse directions. When the hydraulic motor 1 is loaded with a load more than the set value, it has a function of avoiding the pair of oil supply / discharge passages 3 and 4 from being drained by short-circuiting, and a function of mitigating a start shock or a reverse shock of the hydraulic motor 1. A hydraulic pressure grading mechanism A is provided.

FIG. 2 shows a hydraulic pressure grading mechanism A, which comprises a pair of relief valves 7 and 8 for discharging oil when the hydraulic pressure in the oil supply and discharge oil passages 3 and 4 exceeds a predetermined value, and a pair of winding springs 12 and 12. A pair of oil chambers 10 and 11 is urged by a piston 9 biased to a predetermined position.
Of the cushion portion 15 that is urged to return to a predetermined volume, and the connection oil passages 13 and 1 that communicate the pressure supply side oil passages 5 and 6 and the oil chambers 10 and 11 of the relief valves 7 and 8, respectively.
4 and 4 are internally mounted in the valve casing 16.

Explaining the structure of the relief valves 7, 8 on one side, the valve body 7A screwed to the valve casing 16, the moving piece 7a, the receiving piece 7b, the sliding contact ring 7c having the short-circuit hole 17 formed therein, Spacer 7d, relief spring 7e
And the like, and is connected to the oil supply / discharge oil passage 3
The hydraulic oil supplied from 3 enters the internal space of the valve body 7A through the inside of the spacer 7d and the moving piece 7a, and enters from the communication hole S formed in the valve body 7A into the oil chamber 10 of the cushion portion 15. Is configured to be supplied to. The relief pressure can be changed and set by adjusting the position of the receiving piece 7b with the bolt 18 and the lock nut 19. If the relief pressure is exceeded, the moving piece 7a moves to the receiving piece 7b side. However, even if it passes through the short-circuit hole 17 of the sliding contact ring 7c and the supply / discharge port P4, it is short-circuited to the other supply / discharge oil passage 4.

Further, each of the connecting oil passages 13 and 14 formed in the valve casing 16 is equipped with a throttle member 21 having an orifice 20 for reducing the cross-sectional area thereof. More specifically, the throttle member 21 is formed of a male screw member having a small-diameter orifice 20 formed therethrough, and is formed at the end of the connection oil passage 13 on the oil chamber 10 side.
This is a structure in which the threaded portion 13a having a large step diameter is screwed.

In the state shown in FIG. 1, the control valve 2 is set to the neutral position N.
The hydraulic motor 1 is operated in the stopped state. When the control valve 2 is operated to the right rotation position R, for example, from this state, hydraulic oil is supplied from the control valve 2 to the hydraulic motor 1 through the oil passage 3 and the hydraulic motor 1 starts rotating to the right. In this case, the working oil is supplied to the hydraulic motor 1 and at the same time, the working oil from the control valve 2 is also supplied to the one oil chamber 10 of the cushion portion 15 via the supply / discharge oil passage 3 and the connection oil passage 13. Then, the piston 9 moves leftward on the paper surface and compresses the spring 12 of the oil chamber 11 on the opposite side. Therefore, when the hydraulic motor 1 starts to rotate, the hydraulic oil for the hydraulic motor 1 is temporarily used for compression of the spring 12 of the cushion portion 15 by the pushing movement of the piston 9 to suppress a rapid increase in pressure. As a result, the hydraulic motor 1 starts rotating smoothly with less shock.

In the configuration shown in FIG. 1, when the control valve 2 is operated to the right rotation position R and the hydraulic motor 1 is rotating to the right, the control valve 2 is rotated from the right rotation position R to the left. When suddenly operated to the position L, the hydraulic motor 1 and the cushion portion 1
5, the hydraulic oil is discharged from one of the oil chambers 10, and the hydraulic oil is supplied to the oil passage 4 and the other oil chamber 11 on the opposite side, so that the hydraulic motor 1 starts to rotate to the left. Even at this time, the expansion of the other oil chamber 11 suppresses a rapid increase in pressure, and the hydraulic motor 1 starts rotating to the left with less shock from the state of rotating to the right. This state also occurs when the control valve 2 is suddenly operated from the left rotation position L to the right rotation position R.

The above shockless action is brought about by the gradual increase of the supply pressure of the hydraulic oil, and its characteristics can be changed by the orifice 20 of the connecting oil passages 13 and 14. Therefore, for the difference in the model, the hydraulic pressure, etc., only the throttle member 21 needs to be changed, and all other parts in the hydraulic pressure grading mechanism A can be commonly used.

[Other Embodiments] In the above embodiment, the hydraulic pressure grading mechanism A is provided with a pair of relief valves 7 and 8 and a pair of oil chambers 10 and 11 to act on both forward and reverse rotations of the hydraulic motor 1. However, for example, a single relief valve 7 and a cushion portion 15 provided with a single oil chamber 10 are provided in the valve casing 16 in order to mitigate a start shock of the single-acting hydraulic cylinder for lifting the mower. The present invention may be applied to the gradually changing hydraulic pressure mechanism A. In this alternative embodiment, the piston 9
May be biased toward the stopper so that the volume of the oil chamber 10 becomes a predetermined minimum volume.

Further, in this embodiment, the pair of springs 12 and 12 are
The piston 9 is biased and returned to a position where the oil chamber 10 is balanced, but even in this structure, there is spring resistance in the direction in which the oil chamber 10 expands from the balanced state, and “the volume of the oil chamber (10) is reduced. It is defined as satisfying the condition of being urged to return.

As the mounting structure of the throttle member 21 to the connecting oil passage 13, in addition to a detachable screwing structure, driving or press fitting, or the throttle member 21 fitted with an annular oil seal is pulled out by a snap ring. Various things are considered, such as stopping.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 Operating circuit diagram of hydraulic motor

FIG. 2 is a sectional view of the grading mechanism.

FIG. 3 is a sectional view of a conventional grading mechanism.

[Explanation of symbols]

 1 Hydraulic Actuator 2 Control Valve 3 Supply / Discharge Oil Path 7 Relief Valve 9 Piston 10 Oil Chamber 13 Connection Oil Path 20 Orifice 21 Throttle Member

Claims (1)

[Claims] 1. A hydraulic pressure grading mechanism communicating with a supply / discharge oil passage (3) connecting a hydraulic actuator (1) and a control valve (2) for the hydraulic actuator (1), wherein the supply / discharge mechanism comprises: A relief valve (7) that drains oil when the oil pressure in the oil passage (3) exceeds a predetermined level, and a cushion portion that is urged to return the volume of the oil chamber (10) to the reduction side by a spring-biased piston (9). (15) and a connection oil passage (13) that connects the pressure supply side oil passage (5) in the relief valve (7) and the oil chamber (10) are respectively installed in the valve casing (16). A hydraulic pressure grading mechanism in which the connecting oil passage (13) is equipped with a throttle member (21) having an orifice (20) for reducing the cross-sectional area of the connecting oil passage (13).