JPH0341273A - Counterbalance valve - Google Patents

Abstract

PURPOSE:To reduce the number of parts, and facilitate the processing and the assembly, and prevent the leakage at the neutral time by providing a pilot pressure leading hole for opening a load side passage and a damping orifice for making the movement of a spool slow. CONSTITUTION:A spool 7 is always energized by a compressed coil spring 13 to shut a load side passage formed in a valve main frame 1. The fluid pressure in the opposite direction is worked to the load side passage. At the stage, a part of the fluid pressure works on a spool 7 through a pilot pressure leading hole 33 to move the spool 7, resisting the energizing force of the spring 13. The movement of the spool 7 is made slow by the work of a damping orifice 31 fitted in a communicating passage 12 of the spool 7. In this way, the number of parts is reduced, and the processing and the assembly can be facilitated, and the leakage at the neutral time can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a counterbalance valve, and particularly to a counterbalance valve that reduces the number of parts constituting the valve and thereby facilitates processing and assembly.

(Prior Art) A conventional example will be explained with reference to FIGS. 4 and 5. FIG. 4 is a sectional view of the counterbalance valve, and FIG. 5 is a circuit diagram.

The valve body 101 includes a hollow tube 103.

The tube 103 is composed of a column body 105 attached to one end and a bottom 107 attached to the other end.

A spool 109 is slidably housed within the valve body 101, and a closing member 111 is fitted into an opening at one end of the spool 109. A convex portion 113 is formed on this closing member 111, and an end surface of this convex portion 113 serves as a pilot pressure receiving surface 115. Further, the other end of the spool 109 is solid and forms a closed portion 117.

The convex portion 113 is slidably inserted into a pilot pressure introduction hole 119 formed in the plug body 105. on the other hand,
The closing portion 117 is a cylinder 1 formed in the bottom 107.
It is slidably inserted into 21.

A chamber 1 is located between both ends of the spool 109 and the valve body 101.
23 and 125 are formed respectively.

Further, a check valve 127 is provided within the spool 109. This check valve 127 includes a pole-shaped valve body 129,
A spring 133 biases the pole-shaped valve body 129 in the right direction in the figure via a member 131.

Hollow portions 135 and 137 are formed in the spool 109 by the check valve 127, and the check valve 127 only allows flow from the hollow portion 137 toward the 135.

The chambers 123 and 125 communicate with each other via a hollow portion 135. That is, the chamber 123 communicates with the hollow portion 135 via the flow path 139 and the damping orifice 141. On the other hand, the chamber 125 has a damping orifice 143
, communicates with the hollow portion 135 via a flow path 145.

In addition, the spool 109 normally has a compression coil spring 1.
47 in the left direction in FIG. This blocks the flow from ports 151 to 153.

A counterbalance valve having such a configuration is used by being inserted into a circuit as shown in FIG. 5, for example. This circuit is for raising and lowering the workpiece 155.

Work 155 is connected to cylinder 157. Further, the bow) 151 is communicated with the chamber A of the cylinder 157, and the bow) 153 is communicated with the direction switching j-t 159. Further, the directional switching valve 159 and the chamber of the cylinder 157 are communicated with each other. Further, the pilot pressure introduction hole 119 is communicated with a branch passage 161 of a passage communicating the directional switching valve 159 and the chamber B of the cylinder 157.

Note that a hydraulic pump 163 and a tank 165 are connected to the directional switching valve 159.

First, the directional switching valve 159 is switched to the right position in the figure.

Pressure oil from the hydraulic pump 163 flows into the valve body 101 via the boat 153. The pressure oil that has flowed into the valve body 101 flows into the hollow portion 137 through the inflow hole 167, opens the check valve 127, and flows through the outflow hole 169 and the bow).
151 into the chamber A of the cylinder 157.

As a result, the cylinder 157 is raised and the workpiece 15
5 will also rise.

Next, the directional control valve 159 is switched to the left position in the figure.

The pressure oil from the hydraulic pump 163 is transferred to the chamber B of the cylinder 157.
A part of it is introduced into the pilot pressure introduction hole 119 via the branch passage 161.

The pressure introduced into the pilot pressure introduction hole 119 acts on the pilot pressure receiving pressure surface 115 and moves the spool 109 to the right in the figure against the spring force of the compression coil spring 147.

At this time, the damping orifices 143 and 141 act to slow the movement of the spool 109 to the right in the figure. As the spool 109 moves, the tapered portion 149 separates from the step portion 150, opening the flow path from the bow 151 to the bow 153. Therefore, chamber A of cylinder 157
The pressure oil inside returns to the tank 165.

In this manner, the damping orifices 143 and 141 allow the spool 109 to move slowly, thereby preventing the cylinder 157 from dropping rapidly.

(Problems to be solved by the present invention) According to the above conventional configuration, there were the following problems.

First, there are a large number of parts, and it is difficult to accurately process and assemble these many parts.

Furthermore, if the machining accuracy and assembly accuracy are poor, reliability will be reduced, especially in the tapered portion 14.
If the pressure contact between the step portion 9 and the stepped portion 150 is impaired, there is a concern that there may be a middle support leak.

The present invention was made based on these points, and its purpose is to reduce the number of parts by reducing the number of parts.
It is an object of the present invention to provide a counterbalance valve that is easy to process and assemble and can prevent leakage when in neutral.

(Means for Solving the Problems) In order to achieve the above object, a counterbalance valve according to the present invention includes a valve body, which is slidably housed within the valve body, and which is normally formed in the valve body by an elastic member. The communication passage is biased so as to close the load-side passage, and communicates the chambers formed on both sides in the axial direction, and a part of the communication passage functions as a detour bypassing the load-side passage. a spool provided with the spool, and a valve provided in a detour portion of the communication path of the spool, the valve being opened by unidirectional fluid pressure acting on the load side path. A check valve that allows flow only from the one direction, and a check valve formed on the side of the valve body to introduce pilot pressure to move the spool against the biasing force of the elastic member to move the spool to the load side. It is characterized by comprising a pilot pressure introduction hole that opens a passage, and a damping orifice that is attached to the communication passage of the spool and slows down the movement of the spool.

(Operation of the present invention) The spool is constantly biased by an elastic member and blocks the load-side passage formed in the valve body.

In this state, when fluid pressure is applied from one direction to the load-side passage in order to cause the load to perform a desired operation, the check valve is opened by the fluid pressure. Fluid is diverted through the spool through the check valve to effect the desired operation.

Next, when restoring the load, fluid pressure in the opposite direction is applied to the load side passage. At this time, part of the fluid pressure acts on the spool through the pilot pressure introduction hole, and moves the spool against the biasing force of the elastic member.

As a result, the load-side passage of the valve body is opened, flow in the opposite direction of the load-side passage is allowed, and the load is restored.

At this time, the spool moves slowly due to the action of the damping orifice installed in the communication path of the spool, and the load side path is gradually opened, so that the load is returned slowly.

(Embodiment of the present invention) A first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a sectional view of a counterbalance valve according to this embodiment.

The valve body 1 is hollow, with an opening 3 at one end, and a plug body 5 fitted into the other end.

A spool 7 is slidably accommodated within the valve body 1. The spool 7 is hollow, with a boat 9 at one end and a member 11 screwed into the other end. A communication passage lO is formed in the spool 7 in the axial direction, and a communication passage 12 that communicates with the communication passage is also formed in the member 11. The chambers a and b formed on both sides of the spool 7 in the axial direction are communicated via these communication passages lO1 and 12.

A compression coil spring 13 is stretched between the member 11 and the plug body 5 described above, and the spool 7 is constantly biased toward the left in FIG. 1 by the compression coil spring 13.

A stepped portion 15 is formed on the valve body 1, and a tapered portion 17 is formed on the spool 7 side. The compression coil spring 13 moves the tapered portion 17 to the stepped portion 15.
, thereby blocking the load-side passage connecting the boat 9 side and the boat 19 side of the valve body 1.

A check valve 21 is provided in the communication path 10 within the spool 7. This check valve 21 is composed of a hollow valve body 23 and a spring 25 that is stretched between the valve body 23 and the member 11 and constantly urges the valve body 23 to the left in the figure. ing.

A tapered portion 27 is formed at the left end of the valve body 23 in the figure, while a stepped portion 29 is formed on the spool 7 side. The tapered portion 27 is pressed against the stepped portion 29. The check valve 21 only allows flow from the bow 19 toward the port 9 via the detour 14 that is a part of the communication path 1O.

A damping orifice 3 is provided in the passage 12 of the member 11.
1 is installed. The pressure on the load side also acts on the chamber a side via this damping orifice 31. Further, a pilot pressure introduction hole 33 is formed in the side portion of the valve body l. Further, a stepped portion is formed on the spool 7 at the pilot pressure introduction hole 33 position, and that portion serves as a pilot pressure receiving surface 34. The area S of this pilot pressure receiving surface 34 has the following value.

S = tc (a2-b?) / l” (1) However.

a: Diameter of the large diameter part of the step part b = Diameter of the small diameter part of the step part A counterbalance valve with such a configuration has cylinder 3
5 and the direction switching valve 37, and contributes to the lifting and lowering operation of the workpiece 39.

The chamber A of the cylinder 35 and the directional switching valve 37 are connected via a pipe 41. Further, the chamber B of the cylinder 35 and the boat 9 are connected via a pipe 43. Also,
The directional switching valve 37 and the boat 19 are connected via a pipe 45.

A pipe 47 is branched from the pipe 41, and this pipe 47 is connected to the pilot pressure introduction hole 33.

The directional control valve 37 also includes a hydraulic pump 49 and a tank 5.
1 is connected.

The operation will be explained based on the above configuration.

First, the directional switching valve 37 is switched to the right position in the figure. Pressure oil from the hydraulic pump 49 flows into the valve body 1 through the pipe 45 and bow 19, and urges the valve body 23 of the check valve 21 rightward in the figure. Thereby, the check valve 21 is opened, and the pressure oil acts on the chamber B of the cylinder 35 via the detour 14, the boat 9, and the piping 43. As a result, the workpiece 39 is lifted up.

Switch the directional switching valve 37 to the left position in the figure.

Pressure oil from the hydraulic pump 49 acts on the chamber A of the cylinder 35 via the pipe 41. At the same time, pilot pressure acts on the pilot pressure introduction hole 33 via the pipe 47.

Due to the action of this pilot pressure, the spool 7 moves to the right in the figure against the spring force of the compression coil spring 13. As a result, the tapered portion 17 and the stepped portion 15
The pressurized state with the cylinder 37 is released, and the pressure oil from the chamber B of the cylinder 37 flows through the load side passage connecting the opening 3 and the boat 19 and returns to the tank 51 via the piping 45.

At this time, the spool 7 moves slowly due to the action of the damping orifice 31. Therefore, the return of the pressure oil is carried out gradually, and the workpiece 39 is prevented from falling suddenly.

As described above, according to this embodiment, the number of parts constituting the counterbalance valve is reduced, and in particular, the number of parts serving as fitting elements is reduced, and only one damping orifice is required, which greatly facilitates processing and assembly. Became.

Of course, in this case, the counterbalance function is not impaired in any way.

Furthermore, since machining and assembly have become easier, it becomes easier to maintain machining and assembly accuracy, and leaks in neutral are also prevented.

Next, a second embodiment will be described with reference to FIG.

In this embodiment, a boat 61 is formed on the side of the valve body l and the spool 7, and the boat 61 and the chamber B of the cylinder 35 are connected by a pipe 43.

Further, another damping orifice 63 is provided at the left end of the communication path 1o of the spool 7 in the figure.

In this case, not only the same effects as in the first embodiment can be achieved, but also the damping balance function can be further improved.

Next, a third embodiment will be described with reference to FIG. A communication path 72 is formed at one end of the spool 71, and the left end opening in the figure is a boat 73. Spool 71
The other end 75 is solid.

A check valve 77 is provided in the communication path 72. This check valve 77 includes a valve body 79, a collar 81 attached to the spool 71, and a spring 8 that is stretched between the valve body 79 and the collar 81 and always biases the valve body 79 in the right direction.
It is composed of 3.

A tapered portion 84 is formed on the valve body 79, and a stepped portion 86 is formed on the spool 71. The tapered portion 84 is a stepped portion 86
is pressed against.

A communication passage 85 communicating with the communication passage 72 is formed at the other end 75 of the spool 71, and a damping orifice 87 is installed in the communication passage 85.

The rest of the configuration is the same as that of the first embodiment, and is designated by the same reference numerals, and the explanation thereof will be omitted.

The operation will be explained based on the above configuration.

First, the directional switching valve 37 is switched to the right position in the figure. Pressure oil from the hydraulic pump 49 flows into the valve body 1 through the piping 45 and the boat 19, and urges the valve body 79 of the check valve 77 to the left in the figure. As a result, the check valve 77 is opened, and the pressure oil flows through the communication path 72, the boat 73. It acts on the chamber B of the cylinder 35 via the pipe 43. by this,
The workpiece 39 is lifted up.

Switch the directional switching valve 37 to the left position in the figure.

Pressure oil from the hydraulic pump 49 acts on the chamber A of the cylinder 35 via the pipe 41. At the same time, pilot pressure acts on the pilot pressure introduction hole 33 via the pipe 47.

Due to the action of this pilot pressure, the spool 7 moves to the right in the figure against the spring force of the compression coil spring 13. As a result, the pressure oil from the chamber B of the cylinder 37 flows through the load side passage connecting the boats 73 and 19 and returns to the tank 51 via the piping 45.

Due to the action of the damping orifice 87, the spool 7 moves slowly. Therefore, the return of the pressure oil is carried out gradually, and the workpiece 39 is prevented from falling suddenly.

In the case of this embodiment as well, as in the case of the first embodiment, the number of parts is reduced, processing and assembly are facilitated, and
It is possible to prevent leaks when in neutral.

Also in this case, another damping orifice is provided at the left end of the spool 71, and a boat is formed at the side of the valve body l and the spool 71, so that the chamber B of the cylinder 35
The counterbalance function may be further strengthened by connecting with

(Effects of the present invention) As detailed above, according to the counterbalance valve according to the present invention, the number of parts can be reduced, processing and assembly can be facilitated, and leakage in neutral can be prevented. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a counterbalance valve according to a first embodiment of the present invention, FIG. 2 is a partial cross-sectional view of a counterbalance valve according to a second embodiment, and FIG. 3 is a cross-sectional view of a counterbalance valve according to a third embodiment. The sectional view, FIG. 4, and FIG. 5 are views showing a conventional example. FIG. 4 is a sectional view of a counterbalance valve, and FIG. 5 is a circuit diagram. l...Valve body, 7...Spool, 9.19...Boat, 1O112...Communication path, 13...Compression coil spring (elastic member), 14...Detour, 21...
・Check valve, 31...Dumping orifice, 33...
・Pilot pressure introduction hole.

Claims (1)

[Claims] A valve body, which is slidably housed within the valve body, is normally biased by an elastic member to close the load-side passage formed in the valve body, and is formed on both sides of the valve body in the axial direction. a spool having a communication passage that communicates between the two chambers and a part of which functions as a detour to bypass the load-side passage; It is installed in the detour section of
a check valve that opens in response to fluid pressure in one direction acting on the load side passage and allows flow only from the one direction; and a check valve that is formed on the side of the valve body to introduce pilot pressure to the spool a pilot pressure introduction hole that opens the load-side passage by moving it against the biasing force of an elastic member; and a damping orifice that is attached to the communication passage of the spool and slows the movement of the spool. A counterbalance valve characterized by comprising: