JPH06307403A - Operation circuit construction of hydraulic actuator - Google Patents

Abstract

PURPOSE:To restrain shock of a hydraulic actuator when operating direction changeover is operated suddenly in the case when a single piston and a cylinder are used both for normal and reverse operations as a shock moderation at the time of starting a normal operation and a reverse operation of a double acting hydraulic actuator. CONSTITUTION:A cylinder 10, having a piston 9 provided inside in a freely reciprocating manner, is equipped with a pair of spring 11, 12, which connect a pair of oil sacs 10a, 10b on both sides of the piston 10 and a pair of oil passage 3, 4, on a hydraulic actuator 1 together, and provide force to the piston 9 towards the center. The piston 9 is then made to operated smoothly by equipping a throttle oil passage 9a, which communicates both sacs 10a, 10b of the cylinder 9 to each other, on the piston 9 and drawing out operation fluid remaining in one of the pair of sacs 10a, 10b and shifting it to the other sac thereby restraining the shock when the operation direction of hydraulic actuator 1 is suddenly switched over.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operating circuit structure of a double-acting hydraulic actuator such as a hydraulic motor that can rotate forward and backward and a hydraulic cylinder that can operate forward and backward. The present invention relates to a structure for shock mitigation when switching operation is performed in the reverse direction from.

[0002]

2. Description of the Related Art FIG. 4 shows an example of the operation circuit structure of a hydraulic actuator as described above. In this structure, a hydraulic motor 1 (corresponding to a double-acting hydraulic actuator),
The control valve 2 is connected by a pair of oil passages 3 and 4, and the hydraulic motor 1 is rotated in the forward and reverse directions by a supply / discharge operation of hydraulic oil by a switching operation of the control valve 2. A cylinder portion 10 in which a single piston 9 is reciprocally movable is provided, and a pair of oil chambers 10a and 10b formed on both sides of the piston 9 in the cylinder portion 10 and a pair of oils for the hydraulic motor 1 are provided. Road 3,
4 are connected by pilot oil passages 13 and 14, respectively, and a pair of springs 11 and 12 for urging the piston 9 toward the center of the cylinder portion 10 are provided in each of the oil chambers 10a and 10b.

In the state shown in FIG. 4, the control valve 2 is set to the neutral position 2
The hydraulic motor 1 operated to N is in a stopped state. When the control valve 2 is operated to the right rotation position 2R, 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, at the same time as the hydraulic oil is supplied to the hydraulic motor 1, the hydraulic oil from the control valve 2 is also supplied to the one oil chamber 10a of the cylinder portion 10 via the oil passage 3 and the pilot oil passage 13. The piston 9 moves to the right in the drawing and the spring 1 of the oil chamber 10b on the opposite side is moved.
2 is compressed. In this way, 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 cylinder portion 10 to suppress a rapid increase in pressure. It starts rotating smoothly with less shock.

[0004]

In the conventional configuration shown in FIG. 4, for example, the control valve 2 is operated to the right rotation position 2R,
It is assumed that the hydraulic motor 1 is rotating to the right. In this case, since the hydraulic motor 1 is a double-acting type, the hydraulic oil from the oil passage 3 rotates the hydraulic motor 1 to the right, and at the same time, the hydraulic motor 1 is operated with a certain pressure in the oil passage 4 on the opposite side. Oil is drained.

Therefore, when the control valve 2 is suddenly operated from the right rotation position 2R to the left rotation position 2L in this state, when the control valve 2 is operated to the left rotation position 2L, the oil of the hydraulic motor 1 and the cylinder portion 10 is changed. The hydraulic oil should escape from the chamber 10a, but if the control valve 2 is suddenly operated as described above, the hydraulic oil is not sufficiently released, and the hydraulic motor is passed through the oil passage 4 on the opposite side from the control valve 2. 1, hydraulic oil is supplied, and the hydraulic motor 1 starts to rotate to the left. In this case, hydraulic oil is supplied from the oil passage 4 on the opposite side to the oil chamber 10b of the cylinder portion 10 to move the piston 9 to the left in the drawing, and the hydraulic motor 1 smoothly moves to the left as in the description of the conventional technique. Although it should start rotating, as described above, the oil chamber 10a of the cylinder portion 10
If the hydraulic fluid from the oil passage 4 on the opposite side is used to move the piston 9 to the left in the drawing, the hydraulic fluid from the oil passage 4 on the opposite side does not escape sufficiently and hydraulic fluid with a certain pressure remains in the oil chamber 10a. It becomes impossible to move.

When the piston cannot move in this way, it cannot be said that the hydraulic oil for the hydraulic motor is temporarily used for compression of the spring of the cylinder portion, so a shock is generated at the start of rotation of the hydraulic motor. Will occur. The present invention provides a double-acting hydraulic actuator with a shock-relieving cylinder portion and a piston as described above, and provides a shock when switching the operating direction of the hydraulic actuator from one direction to the opposite direction. The purpose is to suppress.

[0007]

The feature of the present invention resides in the following construction in the operation circuit structure of the hydraulic actuator as described above. In other words, a double-acting hydraulic actuator and a control valve that supplies and discharges hydraulic oil to and from the hydraulic actuator via a pair of oil passages to operate the hydraulic actuator in the forward and reverse directions are provided, and a single piston is reciprocated. A cylinder part that movably accommodates is provided, and a pair of oil chambers formed on both sides of the piston in the cylinder part and a pair of oil passages to the hydraulic actuator are connected to each other, and the piston is located on the center side of the cylinder part. Each of the oil chambers is provided with a pair of springs for urging the pistons, and the piston is provided with a throttle oil passage that connects the two oil chambers of the cylinder portion.

[0008]

With the structure of the present invention, for example, in the structure shown in FIG. 1, the control valve 2 is moved to the position 2R to operate the hydraulic actuator 1 in one direction, and the control valve 2 is moved to the opposite position 2L. Suppose that you suddenly operated. At this time, when the control valve 2 is operated to the opposite position 2L, the hydraulic oil should escape from the hydraulic chamber 1 and the oil chamber 10a of the cylinder portion 10. However, if the control valve 2 is suddenly operated in this way. When the hydraulic oil is not sufficiently drained, the hydraulic actuator 1 is passed from the control valve 2 through the oil passage 4 on the opposite side.
Is supplied with hydraulic oil, and the hydraulic actuator 1 starts to operate in the reverse direction.

In this case, when hydraulic oil is supplied from the oil passage 4 on the opposite side to the oil chamber 10b of the cylinder portion 10 and the piston 9 tries to move to the left side of the drawing, the throttle oil passage 9a as in the present invention is used. With the provision, the hydraulic oil in the oil chamber 10b pushes the piston 9 to the left in the drawing, whereby the hydraulic oil remaining in the oil chamber 10a passes through the throttle oil passage 9a of the piston 9 and the oil chamber 10a.
It comes in in b. Therefore, the hydraulic oil in the oil chamber 10b can push the piston 9 to the left in the drawing to compress the spring 11 in the oil chamber 10a, and the hydraulic oil in the oil chamber 10a will eventually escape. 11 can be pushed further to the left on the paper. Thus, even when the control valve 2 is suddenly operated from the one position 2R to the opposite position 2L, the hydraulic actuator 1 starts to operate in the opposite direction with less shock from the state in which the hydraulic actuator 1 operates in one direction.

[0010]

As described above, in the operation circuit structure including the shock absorbing cylinder portion and the piston as described above for the double-acting hydraulic actuator, the operating direction of the hydraulic actuator is suddenly switched. At this time, the hydraulic oil in the oil chamber on the side that will resist the movement of the piston can be drained to the oil chamber on the opposite side and the piston can be moved without hindrance, and the operating direction of the hydraulic actuator was suddenly switched. It became possible to suppress the shock at the time, and the stability of the operation of the hydraulic actuator could be improved. Also, since it is only necessary to provide a small throttle oil passage in the piston, the structure is simple and the manufacture is easy.
It is also advantageous in terms of manufacturing cost.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows a wheel loader for civil engineering
The operation circuit structure of the hydraulic motor 1 (corresponding to a double-acting hydraulic actuator) that rotationally drives the traveling wheels in the reverse direction is shown. As shown in FIG. 1, a hydraulic motor 1 and a three-position switching type control valve 2 are connected by a pair of oil passages 3 and 4, and hydraulic oil from a hydraulic pump (not shown) is switched to the control valve 2. The hydraulic motor 1 is supplied / discharged by operation to rotate the hydraulic motor 1 in the forward and reverse directions. The hydraulic motor 1 is provided with a pair of bypass oil passages 5 and 6 and a normally closed type relief valve 7 and 8 that short-circuit the pair of oil passages 3 and 4 when a load larger than a set value is applied.

As shown in FIG. 1, a cylinder portion 10 in which a single piston 9 is reciprocally movable is provided. In the cylinder portion 10, a pair of oil chambers 1 is provided on both sides of the piston 9.
0a and 10b are formed, and a pair of springs 11 and 12 for urging the piston 9 toward the center of the cylinder portion 10 are provided in both oil chambers 10.
It is provided for each of a and 10b. Relief valve 8 and oil passage 3
And the pilot oil passages 13 and 14 from the bypass oil passage 6 between the relief valve 7 and the oil passage 4, respectively.
a and 10b, respectively. Then, the throttle oil passage 9 that connects the oil chambers 10a and 10b of the cylinder portion 10 to each other.
The piston 9 is provided with a.

In the state shown in FIG. 1, the control valve 2 is set to the neutral position 2
The hydraulic motor 1 operated to N is in a stopped state. When the control valve 2 is operated to the right rotation position 2R, 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 10a of the cylinder portion 10 via the oil passage 3 and the pilot oil passage 13. While the operating oil in the oil chamber 10a passes through the throttle oil passage 9a of the piston 9 and gradually escapes to the opposite oil chamber 10b side, the oil chamber 10a
The piston 9 moves to the right in the drawing by the hydraulic oil inside, and the spring 12 of the oil chamber 10b on the opposite side is compressed. When the hydraulic motor 1 starts to rotate in this way, the hydraulic motor 1
The spring 12 of the cylinder part 10 while slightly draining the hydraulic oil for
The hydraulic motor 1 starts to rotate smoothly with less shock by temporarily using it also for compression of the hydraulic pressure and suppressing a rapid increase in pressure.

In the configuration shown in FIG. 1, it is assumed that the control valve 2 is operated to the right rotation position 2R and the hydraulic motor 1 is rotating to the right. In this case, the hydraulic oil from the oil passage 3 rotates the hydraulic motor 1 to the right, and at the same time, the hydraulic oil having a certain pressure is discharged from the hydraulic motor 1 to the oil passage 4 on the opposite side. When the control valve 2 is suddenly operated from the right rotation position 2R to the left rotation position 2L in this state, the control valve 2
Is operated to the left rotation position 2L, the hydraulic oil should escape from the hydraulic chamber 1a of the hydraulic motor 1 and the cylinder portion 10. However, when the control valve 2 is suddenly operated in this way, the hydraulic oil is sufficiently released. In this state, hydraulic oil is supplied from the control valve 2 to the hydraulic motor 1 via the oil passage 4 on the opposite side, and the hydraulic motor 1 tries to start rotating to the left.

In this case, when hydraulic oil is supplied from the oil passage 4 on the opposite side to the oil chamber 10b of the cylinder portion 10 through the pilot oil passage 14 and the piston 9 tries to move to the left side of the drawing, the oil chamber 10b of the oil chamber 10b moves. By the action of the hydraulic oil pushing the piston 9 to the left in the drawing, the hydraulic oil remaining in the oil chamber 10a passes through the throttle oil passage 9a of the piston 9 and enters the oil chamber 10b. Therefore, the piston 9 can be pushed to the left side of the drawing by the working oil in the oil chamber 10b to compress the spring 11 in the oil chamber 10a, and the working oil in the oil chamber 10a will pass through the pilot oil passage 13 during that time. Therefore, the piston 9 and the spring 11 can be pushed further leftward in the drawing. As a result, the control valve 2 is moved from the right rotation position 2R to the left rotation position 2R.
Even in the case of sudden operation to L, the rapid increase in pressure is suppressed and the hydraulic motor 1 starts to rotate 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 2L to the right rotation position 2R.

[First Embodiment] In the configuration shown in FIG. 1, the piston 9 is directly drilled to form the throttle oil passage 9a. However, as shown in FIG. The opening 9b may be formed, and a pair of orifice members 15 having a thin throttle hole 15a (corresponding to a throttle oil passage) at the bottom may be fixed in the aperture 9b of the piston 9.

[Second Embodiment] As shown in FIG. 3 in the structure shown in FIG. 2, a metal ball 16 having an outer diameter slightly smaller than the inner diameter of the opening 9b of the piston 9 is opened. The ball 16 may be provided in the hole 9b so as to have a function like a check valve. That is, when the control valve 2 in FIG. 1 is operated to the right rotation position 2R, for example, hydraulic oil is supplied from the oil passage 3 to the oil chamber 10a of the cylinder portion 10 as shown in FIG. When you start moving,
The hydraulic oil in the oil chamber 10a passes through the throttle hole 15a of the piston 9 and enters the oil chamber 10b. The ball 16 accordingly moves inside the piston 9 in the orifice 9 on the right side of the drawing.
Of the orifice member 15
5a is closed to block the escape of hydraulic oil from the oil chamber 10a to the oil chamber 10b. The present invention can be applied not only to the hydraulic motor 1 shown in FIG. 1 but also to a double-acting hydraulic cylinder.

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

[Brief description of drawings]

FIG. 1 is an operation circuit diagram of a hydraulic motor, a cylinder portion, a piston, and the like.

FIG. 2 is a sectional view around a cylinder portion and a piston in the first alternative embodiment.

FIG. 3 is a sectional view of the vicinity of a cylinder portion and a piston in a second alternative embodiment.

FIG. 4 is an operation circuit diagram of a hydraulic motor, a cylinder portion, a piston, etc. in a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic actuator 2 Control valve 3,4 Oil passage 9 Piston 9a, 15a Throttling oil passage 10 Cylinder part 10a, 10b Oil chamber 11, 12 Spring

Claims (1)

[Claims] 1. A double-acting hydraulic actuator (1),
The hydraulic actuator (1) has a pair of oil passages (3),
A control valve (2) for supplying / discharging hydraulic oil via (4) and operating the hydraulic actuator (1) in the forward and reverse directions is provided, and a single piston (9) is internally reciprocally movable. A pair of oil chambers (10a), (10b) provided on both sides of the piston (9) in the cylinder portion (10) and a pair of oil pressure actuators (1). A pair of springs (11) and (12) for connecting the oil passages (3) and (4) to each other and biasing the piston (9) toward the center of the cylinder portion (10) are connected to the oil chamber (10a). ), (10b), the throttle oil passages (9a), (15a) communicating with the oil chambers (10a), (10b) of the cylinder part (10) are provided in the piston (9).
Hydraulic actuator operation circuit structure provided in.