JPH0239044Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cushion valve device for a pneumatic cylinder used to stop the piston operation of the pneumatic cylinder.

Generally, a pneumatic cylinder is equipped with a cushion mechanism at its stroke end. As shown in FIG. 1, this conventional cushion mechanism closes a main flow passage 4 by means of a spool-shaped valve body 3 protruding from the end face of a piston 2 at the end of a cylinder 1. A check valve 5 and an orifice 6 are provided between the inside of the valve body 3 and the main flow path 4 is connected to the valve body 3.
After being closed by the orifice 6, the operation of the piston 2 is gradually stopped by exhausting the air little by little through the orifice 6. When the next operation is to be performed in the opposite direction, the air supplied from the main flow path 4 is Generally, the check valve 5 is pushed open so that the water is supplied into the cylinder 1. Conventional cushion mechanisms like this have the disadvantage that high-pressure air flows only in one direction within the orifice, which can cause dust to accumulate and cause changes in the flow rate. There was a problem in that it could not adequately respond to changes in usage conditions.

On the other hand, as a friction valve device for stopping the piston of such a pneumatic cylinder before its maximum stroke, as shown in FIG. A spool valve 14 is provided between the secondary flow path 13 communicated with the spool valve 12 side, and the valve body 14a of this spool valve 14 is operated via a lever 15, and this lever 15 has a piece that is interlocked with a piston. The cushion valve device is configured such that when the lever 15 is pressed, the valve body 14a is operated, and the gap with the valve seat 14b is gradually reduced to perform a cushioning action. Are known. This conventional cushion valve device allows the cylinder to be used with a stroke smaller than the maximum stroke,
This works well when the piston moves slowly, but when it moves quickly, the cushioning action is insufficient and the inertia of the piston increases the pressure on the secondary side of the pneumatic cylinder, resulting in a reverse action. It was hot.

In consideration of the above-mentioned conventional problems, the present invention provides good cushioning action without causing reaction even when the piston operating speed is increased.
The purpose of this feature is to provide an exhaust flow path of a pneumatic cylinder with an exhaust flow path when the cylinder reaches the desired set operating position. an on-off valve that closes the on-off valve, a check valve that is connected in parallel with the on-off valve to stop the flow in the exhaust direction, and a variable load spring, and the upstream side of the on-off valve in the exhaust flow path increases the pressure to a predetermined pressure or higher. and an exhaust regulating valve that opens when the exhaust regulating valve is opened, and the sum of the pressure on the air supply flow path side and the spring load of the variable load spring is used as the pilot pressure when opening the exhaust regulating valve. When the passage is closed by the on-off valve, the pressure on the upstream side thereof is increased, and when the pressure is greater than the sum of the air supply side pressure of the pneumatic cylinder and the spring load, the exhaust is caused to be exhausted by the exhaust adjustment valve. The cushioning action was made to take place.

Next, an example of the implementation of the present invention will be explained with reference to the drawings from FIG. 3 onwards.

FIG. 3 shows the pneumatic circuit of this device, and FIG. 4 shows the structure of its main parts. In the figure, 20 is a cylinder, 21 is a piston of the cylinder, and 22
is an in/out movement rod. The cylinder 20 is equipped with a pair of air supply and exhaust holes 20a and 20b at both ends, and the operating speed of the piston 21 is controlled by feeding pressurized air from one side and controlling the amount of air discharged from the other side (not shown). We are trying to adjust the
In addition, the direction of operation of the piston 21 is switched by connecting the pressure supply source 23 and the exhaust path 24 to the flow path communicating with both the supply and exhaust holes 20a and 20b using a switching valve 25. ing. In the description of this embodiment, for convenience, the air supply side during the work operation of the piston 21 will be referred to as the air supply flow path 26, and the exhaust side will be referred to as the exhaust flow path 27.
Therefore, the return movement of the piston 21 is performed by communicating the exhaust flow path 27 and the pressure supply source 23 through the switching valve 25.

The exhaust flow path 27 described above is equipped with an on-off valve 28 that opens and closes the flow path. This on-off valve 28 uses a spool valve body 28a as shown in FIG.
The flow path is closed by being pushed in by a cam 30 (shown in FIG. 3) provided at 2.

Further, the exhaust flow path 27 is provided with a check valve 31 and an exhaust regulating valve 32 in parallel with the on-off valve 28, respectively. This check valve 31 blocks the flow from the cylinder 21 side to the switching valve 25 side, and allows free flow in the opposite direction.As shown in FIG. On the other hand, it is constructed with a valve body 35 pressed by a spring 34. Furthermore, the exhaust regulating valve 32 opens the flow path to exhaust air when the pressure on the head side 20c of the cylinder 20 from which the moving rod 22 protrudes exceeds a predetermined pressure. The pressure obtained by adding the load of the variable load spring 36, which can be controlled by a pressure adjustment valve from the outside, to the pressure of the air supply flow path 26 is used. That is, as shown in FIG. 4, a valve chamber 38 is provided in the middle of the bypass passage 37 from the head side 20c to the switching valve 25, and a valve seat 39 is inserted into the valve chamber 38 against the internal pressure of the head side 20c.
The poppet valve body 40 is provided with a poppet valve body 40 that is pressed against the flow path and closes the flow path, and a piston 41 is mounted on the back surface of the poppet valve body 40.
The air supply flow path 26 is connected to the pilot cylinder 42 into which the piston 41 is inserted, and the variable load spring 36 is attached by pressing the tip with an adjusting screw 43.

The exhaust regulating valve 32 has an inner area S ₁ of the valve body 39 that the poppet valve body 40 comes into contact with, and a cylinder 2
The pressure on the head side 20c of 0 is P ₁ , the piston 41
, the pressure inside the air supply flow path ₂₆ is P, and the load of the variable load spring 36 is F, then P ₁・
When S ₁ >P·S ₂ +F, the poppet valve body 40 is moved in the opening direction.

As shown in FIG. 4, the pneumatic cylinder cushioning device constructed in this manner is configured such that when the switching valve 25 connects the air supply flow path 26 side to the pressure supply source and moves the piston 21 to the work operation side, this operation is performed. At the end, the cam 30 comes into contact with the roller 28c, and the spool valve body 28a is pushed into the opening/closing valve 28.
is closed, and as a result, the internal pressure between the on-off valve 28 of the exhaust flow path 27 and the cylinder 20 is increased to be higher than the pressure of the air supply flow path 26 due to the pressure from the air supply flow path 26 and the inertia of the piston 21. be done. When this internal pressure reaches a predetermined pressure or higher, the exhaust adjustment valve 32 is opened to overcome the pilot pressure, and while the internal pressure is maintained at a substantially constant pressure corresponding to the pilot pressure, the amount exceeding the predetermined pressure is gradually exhausted. be done. As a result, the piston 21 consumes inertial energy and slowly stops while receiving a cushioning action due to gradual exhaustion.

That is, the cushion valve device for the pneumatic cylinder according to the above embodiment includes a check valve 31 and an exhaust regulating valve 32 connected in parallel with the on-off valve 28 of the exhaust flow path 27, and the pressure of the air supply flow path 26 is used as the pilot pressure. Using the sum of the spring load of the variable load spring 36, the piston 21 of the pneumatic cylinder 20
When stopping the on-off valve 28 on the exhaust flow path 27 side,
By closing, the pressure on its upstream side increases.

On the other hand, the pressure inside the air supply passage 26 is
Cap side 2 where the in/out operation rod 22 does not come out
Since the volume of 0d increases with the movement of the piston 21, the pressure rises at a lower speed than the pressure on the exhaust flow path 27 side and reaches the pressure of the pressure supply source 23, so the pressure in the air supply flow path 26 and The pilot pressure, which is the sum of the spring load, also increases at a slower rate than the pressure on the exhaust flow path 27 side.

This pilot pressure reaches its maximum pressure when the pressure in the air supply flow path 26 reaches the pressure of the pressure supply source 23, but during the process of increasing the pilot pressure, the exhaust flow path 27 side reaches the pilot pressure at that time. When the pressure reaches a predetermined level or higher, the exhaust adjustment valve 32 operates, and exhaust is performed while maintaining the internal pressure of the exhaust flow path 27 at a predetermined pressure. While receiving the action, the stroke end is reached at a slow speed and the stroke end is stopped.

In addition, as part of the pilot pressure, the air supply flow path 2
Since the pressure of piston 2 is used, the pilot pressure automatically changes according to the change in the operating pressure due to the change in the working pressure, and the piston 2 changes in accordance with the change in the operating pressure.
Good cushioning action of 1 is obtained under a wide range of conditions.

Although the above-described embodiment shows a case in which the opening/closing valve of the exhaust flow path is closed by a cam, it is also possible to use a solenoid valve that is operated by an electric signal. It is something.

The cushion valve device for a pneumatic cylinder according to the present invention is provided with an on-off valve in the exhaust flow path as described above, and in parallel with the on-off valve, a check valve that stops the flow in the exhaust direction and an exhaust adjustment valve. The pressure in the air supply flow path and the set value by the variable load spring are used together as the pilot pressure of the exhaust adjustment valve to stop the piston of the pneumatic cylinder, and the rapid exhaust side during the compression stroke of the pneumatic cylinder is This method differs from the conventional exhaust means using a fixed orifice as shown in Figure 1 in dealing with pressure rises, and even when the piston is operated at high speed, it is possible to obtain the exhaust adjustment valve opening corresponding to the exhaust side pressure at that time. This makes it possible to reliably prevent reverse operation due to high pressure on the exhaust side of the pneumatic cylinder.

In addition, when changing the working pressure, since the pressure inside the cylinder's air supply flow path is used as the pilot pressure, the operation of the exhaust regulating valve is controlled by the pilot pressure corresponding to the cylinder operating pressure. Changes can be easily accommodated.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an example of a conventional cushion device at the stroke end of a pneumatic cylinder, FIG. 2 is a cross-sectional view of another conventional cushion valve, FIG. 3 is a circuit diagram of an example of the implementation of the present invention, and FIG. The figure is a sectional view of the main part. 20... pneumatic cylinder, 21... piston,
25...Switching valve, 26...Air supply channel, 27...Exhaust channel, 28...Opening/closing valve, 31...Check valve, 32
...Exhaust adjustment valve, 36...Load variable spring.

Claims (1)

[Scope of utility model registration request] an on-off valve in the exhaust flow path of the pneumatic cylinder that closes the exhaust flow path when the cylinder reaches a desired set operating position; and a check valve connected in parallel with the on-off valve to stop the flow in the exhaust direction; an exhaust regulating valve that has a variable load spring and is opened when the pressure on the upstream side of the on-off valve of the exhaust passage increases to a predetermined pressure or higher; A cushion valve device for a pneumatic cylinder that uses the sum of the pressure on the air flow path side and the spring load of the variable load spring.