JPH0241363Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a switching valve that is switched and driven by pilot hydraulic pressure, and in particular controls the moving speed of the main spool when the valve is opened to provide a shock to the load. This invention relates to a shockless switching valve that eliminates the above.

[Conventional technology]

An example of a conventional shockless switching valve is the one disclosed in Japanese Patent Publication No. 55-9590.

To briefly explain this with reference to FIG. A pair of main springs 5, 5' housed in end chambers 4, 4' hold the valve in the neutral closed position.

Further, at both ends of the body 2, a housing 6,
6' are integrally fixed, and this housing 6,
A pair of pilot pistons 7, 7' facing both ends of the main spool 3 are arranged at 6', and oil grooves 8, 8' in the middle thereof are directly communicated with a pair of pilot ports _P1 , _P2, respectively. 2 oil chambers 9, 9' at the rear of each pilot piston 7, 7'.
Individual throttle valves 10, 10 and check valves 11, 1
1 and throttle valve 10', 10' and check valve 11',
It communicates with pilot ports P ₁ and P ₂ through each combination circuit 11'.

When, for example, solenoid a of the pilot solenoid valve 12 is energized from the neutral (closed) state shown in the figure, pilot pressure oil from the pilot hydraulic pressure source 13 first flows into the oil groove 8 from the pilot port P ₁ without resistance, and the pilot It also flows into the oil chamber 9 through the oil hole 7a in the piston 7.

On the other hand, the oil in the right oil chamber 9' flows out from the pilot port _P2 into the tank 14 without resistance through the oil hole 7a' and the oil groove 8' in the pilot piston 7'.

Therefore, the pilot piston 7 moves the main spool 3 and the other pilot piston 7' to the right at high speed.

As a result, when the pressure oil supply port P leading to the hydraulic power source 15 and the cylinder port A leading to one end of the cylinder 16 begin to open, and the gap between the cylinder port B leading to the other end of the cylinder 16 and the tank port T begins to open. Since the pilot piston 7 closes the oil groove 8, the flow rate of the pilot pressure oil flowing into the oil chamber 9 is adjusted by the circuit of the check valve 11 and the throttle valve 10 in a meter-in manner.

Therefore, the movement speed of the main spool 3 to the right by the pilot piston 7 decreases, and the valve gradually opens to slowly increase the amount of oil flowing into and out of the cylinder 16, so that the cylinder 16 slides without shock. The piston rod 16a is then started and accelerated, and the piston rod 16a is moved backward.

By energizing the solenoid b of the pilot electromagnetic valve 12, the cylinder 16 can be started and accelerated in the same manner without a shock, and the piston rod 16a can be moved forward.

Note that oil leaked into the spool end chambers 4, 4' from the small gaps between the main spool 3 and the pilot pistons 7, 7' when the cylinder 16 moves forward or backward,
They are recovered to the tank through drain lines 17, 17', respectively.

[The problem that the idea aims to solve]

However, such a conventional shotless switching valve not only requires a pair of pilot pistons 7, 7' to drive the main spool 3, but also requires a pair of pilot pistons 7, 7' to drive the main spool 3.
In order to communicate the rear oil chambers 9, 9' with the pilot ports _P1 , _P2 via a combination circuit of a throttle valve and a check valve, it is necessary to lead out a pilot line to the outside.

Furthermore, it is necessary to increase the number of throttle valves and check valves constituting the combination circuit, and furthermore, it is necessary to provide a drain oil passage in the spool end chamber and connect the drain pipe.

This not only complicates the structure of the valve, but also
The disadvantage is that the valve becomes larger.

This invention has been made in view of the above points, and aims to provide a pilot type shotless switching valve that does not require an external pilot line, has an extremely simple structure, and does not require an increase in the size of the valve. purpose.

[Means to solve the problem]

Therefore, the pilot-type shockless switching valve according to this invention has push rods protruding from both ends of the main spool that protrudes into each spool end chamber of the switching valve as described above, and each tip of the main spool is fixed to the inner surface of the housing. The main spool is inserted into the center hole of the holder and communicated with the center hole to form a piston chamber in the housing, and the main spool is biased in the push rod direction by a spring in each piston chamber. A piston is slidably provided to be locked at a position having a predetermined distance between the tip end face of the push rod and the main spool and the sliding hole when the valve is in the valve closing position.

An oil passage is formed in the body that accommodates the main spool to communicate each spool end chamber with a pair of pilot ports, and an oil passage is formed in each holder to form a gap between the tip end surface of the push rod in the center hole and the piston. forming an oil passage hole that communicates with each of the spool end chambers, and forming an oil passage in each of the housings that communicates each piston chamber with each spool end chamber through a throttle valve,
The pilot flow rate is controlled using a meter-out method to perform a shotless valve opening operation.

[Effect]

The pilot type shotless switching valve according to this invention is constructed as described above, so that when the main spool is in the neutral closed position, the pilot solenoid valve is energized and one of the pair of pilot ports communicates with the pilot hydraulic pressure source. When the main spool is moved, one end surface of the main spool is pressed by the pilot hydraulic pressure.

At this time, the push rod provided on the other end of the main spool moves together with the main spool and moves within the center hole of the holder, but the oil in the center hole passes through the oil passage hole and flows into the spool end chamber. Missing,
The main spool transfers at high speed because it flows out from the other pilot port to the tank without resistance.

Then, when the main spool moves by the amount of overlap with the sliding hole of the body and begins to open the main oil passage, the push rod comes into contact with the piston,
The through hole and the oil passage hole leading to the spool end chamber of the holder are closed, and the piston is pressed against the biasing force of the spring.

As a result, the piston moves back, but the flow of oil in the piston chamber is controlled by the throttle valve and flows out to the spool end chamber, so the moving speed of the piston is slow, so the main spool transition speed is also slowed down and gradually opened. speak.

Therefore, since the amount of oil flowing out and flowing into the load such as the cylinder is slowly increased, no shock is given to the load.

On the other hand, when the pilot solenoid valve is de-energized from the open state and the pilot port that was connected to the pilot hydraulic pressure source is now connected to the tank, the main spool returns to the neutral position due to the restoring force of the main spring. Return to the main oil passage and close the main oil passage, but at this time, the oil in the center hole of the holder on both sides flows in or out through the oil passage hole that exits to each spool end chamber, so the diameter of this oil passage hole should be made smaller. If this is done, the throttle effect can provide a shotless effect even during return (when the valve is closed).

〔Example〕

An embodiment of this invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a longitudinal cross-sectional view of the left half of a pilot type shockless switching valve showing a first embodiment of this invention, and the same parts as in the conventional example shown in FIG. 1 are given the same reference numerals.

The switching valve in this embodiment also has a main spool 3 slidably provided in a sliding hole 20a formed in a body 20, and is normally held at the neutral (valve closed) position shown in the figure by a pair of main springs 5. ing.

Further, housings 2 are provided at both ends of this body 20.
1 are integrally fixed to form a pair of spool end chambers 22 that accommodate the main spring 5.

Further, in the body 20, these left and right spool end chambers 22 are connected to a pair of pilot ports P ₁ and P _{2 .}
(P ₂ is not shown in Figure 2, but see Figure 1)
An oil passage groove is provided which forms an oil passage 23 which communicates with each separately, and a pressure oil supply port P, cylinder ports A and B, and a pair of tank ports T similar to the body 2 of the switching valve shown in FIG. There is.

On the other hand, push rods 25 are protruded from the end faces of both ends of the main spool 3 that protrude into each spool end chamber 22, and the tips thereof are inserted into the center hole 24a of the holder 24 fixed to the inner surface of the housing 21. It is inserted so that it can slide freely.

The main spring 5 is interposed between the flange portion of the holder 24 and a ring 26 that engages with the land portions 3a near both ends of the main spool 3.

Piston chambers 27 are formed in each housing 21 in communication with the center hole 24a of this holder 24, and a piston 28 is slidably provided in each piston chamber 27.

This piston 28 is fitted with a stopper 31 integrated with an adjusting screw 30 fixed by a lock nut 29.
The main spool 3 is biased toward the push rod 25 by the spring 32 interposed between the main spool 3 and the push rod 25. The holder 2 is placed in the illustrated position with a predetermined interval (x) corresponding to the overlap x of the sliding holes 20a.
It is locked by the end face of 4.

Further, the piston 28 has a through hole 28a having a smaller diameter than the outer diameter of the push rod 25, and a spring hole 28b having a large diameter following the through hole 28a, forming a cylindrical shape, and the peripheral wall thereof has an interval in the sliding direction. First and second communication holes 28c and 28d are provided separately.

Each holder 24 is formed with an oil passage hole 24b that communicates a portion of the center hole 24a with a distance x between the tip end surface of the push rod 25 and the piston 28 to each spool end chamber 22.

The housing 21 is provided with an oil having a width on the inner circumferential surface of the piston chamber 27 so as to constantly communicate with the first communication hole 28c throughout the entire stroke of the piston 28 from the illustrated position to the push rod 25 and retreating. A groove 33 and an oil passage 34 communicating the oil groove 33 with the spool end chamber 22 are formed, and a throttle valve 35 capable of adjusting the degree of restriction is inserted in the middle of the oil passage 34.

Therefore, each piston chamber 27 has a piston 2
The first communication hole 28c of 8 and this oil passage 34 communicate with the spool end chamber 22 via a throttle valve 35.

The housing 21 is further formed with an oil passage 36 for communicating the piston chamber 27 and the spool end chamber 22 without using the throttle valve 35. When the main spool 3 slides to the valve-opening saturation position,
This oil passage 3 is connected by the second communication hole 28d of the piston 28 which is pushed back by the push rod 25.
6 is communicated with the piston chamber 27.

Note that the right half (not shown) of this switching valve is also constructed completely symmetrically with this left half.

Next, the operation when this switching valve is used by connecting a pilot solenoid valve, a cylinder, etc. as in FIG. 1 will be explained.

In the state shown in Figure 2, both the solenoids of the pilot solenoid valves are de-energized, and the pair of pilot ports P ₁ and P ₂ are both connected to the tank.
The main spool 3 is in a neutral closed position, blocking the connections between the hydraulic supply port P and the tank port T and the cylinder ports A (not shown) and B.

From this state, when one solenoid of the pilot solenoid valve (corresponding to solenoid b in Fig. 1) is energized, the pilot port _P2 of the housing 21 on the right side (not shown) of this switching valve is communicated with the pilot oil pressure source, The pilot solenoid valve is switched to communicate the pilot port _P1 with the tank, and the right end face of the main spool 3 is pressed by the pilot hydraulic pressure and moves to the left.

At this time, the push rod 25 moves to the left in the center hole 24a of the holder 24 together with the main spool 3, but the oil in the center hole 24a passes through the oil passage hole 24b and escapes to the spool end chamber 22, and the pilot Since the oil flows out through the oil path 23 to a tank (not shown) without resistance, the main spool 3 is allowed to move to the left at high speed.

Then, the main spool 3 overlaps x with the land portion 3b and the sliding hole 20a of the body 20.
When the pressure oil supply port P and the cylinder port B and between the tank port T and the cylinder port A on the right side (not shown) begin to open, the push rod 25 comes into contact with the piston 28, and the through hole 28a and the cylinder port A begin to open. The oil passage hole 24b of the holder 24 is closed and the piston 28 is pushed to the left.

Therefore, the piston 28 retreats to the left in response to the biasing force of the spring 32, but at this time, the oil in the piston chamber 27 is removed from the first communication hole 28 of the piston 8.
c and the oil passage 34 of the housing 21, the flow rate is controlled by the throttle valve 35 and flows out into the spool end chamber 22.

Therefore, since the retraction speed of this piston 28 is slow, the leftward speed of the main spool 3 is reduced, and the main spool 3 moves leftward at low speed and gradually opens the valve, slowly controlling the amount of oil flowing in and out of the cylinder (not shown). As the piston rod is increased, the cylinder is smoothly advanced and accelerated without a shock, and the piston rod is advanced.

Thereafter, when the valve opening state reaches saturation, the second communication hole 28d of the piston 28 communicates with the oil passage 36, so that the oil in the piston chamber 27 passes through this oil passage 36 to the spool end chamber 22 with resistance. It will flow out without any problem.

Therefore, the piston 28 then moves to the stopper 3.
1, the main spool 3 moves to the left again at high speed while pressing the piston 28 by the push rod 25, thereby completing the valve opening operation.

In this state, when both solenoids of the pilot solenoid valve are de-energized, the main spool 3 returns to the neutral position due to the restoring force of the left main spring 5, and each port is blocked again.

At this time, the oil in the center hole 24a of the right holder 24 flows out from the oil passage hole 24b to the spool end chamber 22, so when the oil returns ( It is possible to provide a shock effect even when the valve is closed.

On the other hand, the piston 28 quickly returns to its original state due to the restoring force of the spring 32, comes into contact with the holder 24 again, is locked, and returns to the state shown in the drawing.

Next, when the other solenoid of the pilot solenoid valve (corresponding to solenoid a in Fig. 1) is energized from the neutral state shown in the figure, the pressure of the pilot oil flowing from the pilot port _P1 causes the main spool 3 to
The left end surface of is pressed, and the main spool 3 slides to the right to connect between the tank port T and cylinder port B, and between the pressure oil supply port P and cylinder port A (not shown).
At this time, the moving speed of the main spool 3 is controlled in three stages: high speed, low speed and high speed, by the right piston 28, as described above.

Therefore, the cylinder (not shown) can be started and accelerated without any shock, and its piston rod can be moved backward.

Note that by rotating the adjusting screw 30 and changing the position of the stopper 31, the movement stroke of the main spool 3 can be adjusted, so this switching valve can also be provided with a flow rate control function.

As described above, according to the shockless switching valve of this embodiment, the moving speed of the main spool is decelerated to apply a shock to the load of the cylinder, etc. from when the oil passage actually begins to open when the valve is opened until it reaches almost the saturated state. Not only can this be avoided, but the total time required to open the valve can be shortened by moving the main spool again at high speed after saturation.

Next, a second embodiment of this invention will be described, in which only the left end portion is shown in FIG. 3. In the same figure, parts corresponding to those in FIG. .

When the main spool 3 slides, this switching valve
The piston 40 performs speed control in stages (high speed - low speed), and the length in the sliding direction is shorter than that of the piston 28 in FIG.
4a and a through hole 40a communicating with the spring 32.
Only a step portion 40b for locking is formed.

On the other hand, the oil passage 34 formed in the housing 21 is always open to the piston chamber 27, and communicates the piston chamber 27 with the spool end chamber 22 via the throttle valve 35, which corresponds to the oil passage 36 in FIG. No road has been established.

Note that the right end portion (not shown) of this switching valve is also constructed completely symmetrically with this left end portion.

Main spool 3 when this switching valve is open
The sliding speed of the push rod 25 is the same as that of the piston 4.
0 and closes the through hole 40a and the oil passage hole 24b of the holder 24, that is, the stroke x corresponding to the overlap between the main spool 3 and the sliding hole 20a (Fig. 2) is at high speed. Then,
While the push rod 25 slides while pressing the piston 40, the oil in the piston chamber 27 flows into the oil passage 3.
Since the flow rate is controlled by the throttle valve 35 and flows out only from the piston 40, it is decelerated by the piston 40 and becomes low speed.

Therefore, even if this switching valve is used, a cylinder (not shown) or the like can be started smoothly without a shock.

Although the adjustment screw 30 in this embodiment cannot adjust the stroke of the main spool 3, it can adjust the biasing force of the spring 32 to adjust the speed during low-speed sliding. However, the adjustment screw 30 and lock nut 29 may be omitted.

In addition, in any of the embodiments, the throttle valve 35
By adjusting the degree of restriction of the main spool 3, the low sliding speed of the main spool 3 can be optimally adjusted so as to obtain a sufficient shockless effect when opening the valve and to prevent the total operation time required for opening the valve from becoming too long. be able to.

Also, the through holes 28a, 4 of the pistons 28, 40
0a is provided so that the oil on both sides of the piston chamber can move and return quickly when the piston returns, but it is not essential as it can also move through the oil passage 34 and the oil passage hole 24b of the holder 24.

Furthermore, although the pistons 28 and 40 are locked at the end face of the holder 24, a locking ring or the like may be provided separately, and the distance between the pistons 28 and 40 from the front end face of the push rod 25 may be set to x as described above. .

Of course, the push rod 25 may be constructed integrally with the main piston 3.

[Effect of idea]

As explained above, the pilot type shockless switching valve according to this invention can perform smooth switching operation without shock, and for this purpose, it is only necessary to provide one pair of throttle valves for controlling the flow rate, and the piston chamber and Since the oil passage is formed to communicate with the pilot port via the main spool end chamber, there is no need to lead the pilot line outside, and there is no need to connect the drain pipe to the spool end chamber as in the conventional case. Since there is no need to do so, the structure is extremely simple and the valve does not become large.

Furthermore, as in the embodiment shown in FIG. 2, the total time required for valve operation can be shortened by controlling the sliding speed of the main spool in three stages: high speed, low speed and high speed.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of a conventional shockless switching valve, FIG. 2 is a vertical cross-sectional view of the left half of the first embodiment of this invention, and FIG. 3 is a vertical cross-sectional view of the left half of the first embodiment of this invention. FIG. 3 is a longitudinal sectional view showing the left end housing portion of the embodiment. 3...Main spool, 5...Main spring, 20...Body, 21...Housing, 23
...Oil passage, 24...Holder, 24a...Through hole,
24b... Oil passage hole, 25... Push rod, 2
7... Piston chamber, 28, 40... Piston, 3
2... Spring, 34, 36... Oil path, 35...
...throttle valve.

Claims (1)

[Claims for Utility Model Registration] A main spool is provided in a sliding hole formed in the body and held in a neutral valve closing position by a pair of main springs, and a housing is secured to each end of the body. In the switching valve, a pair of spool end chambers for accommodating the main spring are formed, wherein a push rod is provided protruding from both ends of the main spool that protrudes into each spool end chamber, and each tip of the push rod is provided with a push rod. Each is fitted into a center hole of a holder fixed to the inner surface of the housing, communicates with the center hole to form a piston chamber in the housing, and is attached in the direction of the push rod by a spring in each piston chamber. a piston that is latched at a position with a predetermined distance corresponding to the overlap between the main spool and the sliding hole between the front end surface of the push rod and the main spool when the main spool is in a neutral valve closing position; is slidably provided in the body, an oil passage is formed in the body to communicate each of the spool end chambers with a pair of pilot ports, and each holder is provided with a piston and a tip surface of the push rod in the center hole thereof. an oil passage hole is formed in each of the housings to communicate the piston chambers with the respective spool end chambers through respective throttle valves; Features a pilot type shotless switching valve.