JP2022090365A - Selector valve - Google Patents

Abstract

To provide a selector valve which can control a flow rate gradually and prevent a delay from occurring in a flow rate switch point when an operation is resumed after use stop.SOLUTION: A selector valve 1 includes a main valve 50 which may move in a sleeve 10 and is provided with: a first passage 31 and a first on-off valve 41 which allow a pilot supply port 26 and an open port 28 to communicate with each other; a second passage 32 and a second on-off valve 42 which allow a supply port 20 and the open port 28 to communicate with each other; a third passage 33 and a third on-off valve 43 which allow the supply port 20 and a first exhaust port 22 to communicate with each other; and a fourth passage 34 which allows the supply port 20 and a second exhaust port 24 to communicate with each other. In the first on-off valve 41 and the second on-off valve 42, a valve body and a valve seat contact with each other or separate from each other in a moving direction of the main valve 50. When pilot supply air is larger than a predetermined pressure, the first on-off valve 41 and the second on-off valve 42 are closed and the third on-off valve 43 is opened. When the pilot supply air is smaller than the predetermined pressure, the first on-off valve 41 and the second on-off valve 42 are opened and the third on-off valve 43 is closed.SELECTED DRAWING: Figure 2

Description

The present invention relates to a switching valve for pneumatic pressure.

Devices using air cylinders are often used in automated equipment lines and the like for assembling mechanical devices and electronic devices. However, if the moving speed of the piston in the air cylinder is increased, the cycle time can be shortened, but on the other hand, there arises a problem that the impact at the time of stopping becomes large and the life of the air cylinder is shortened.

Conventionally, a shock absorber (for example, an oil type) is provided in the mechanism part to which the piston of the air cylinder is connected so that the impact at the time of stopping does not become large even if the moving speed of the piston of the air cylinder is increased. (Piston) A method of alleviating the impact when stopped was common.

Alternatively, a technique relating to an air cylinder with a cushion mechanism for cushioning an impact when stopped by providing a cushion mechanism for cushioning the impact on the air cylinder itself is also disclosed (see Patent Document 1: Japanese Patent Application Laid-Open No. 2003-254303). ..

Japanese Patent Application Laid-Open No. 2003-254303 Japanese Unexamined Patent Publication No. 2014-055631

However, for example, in the case of a configuration in which a shock absorber is provided to alleviate the impact when the piston of the air cylinder is stopped, it is necessary to incorporate the shock absorber into the device, which complicates the mechanism and increases the component cost and assembly cost. Problems such as

In order to solve this problem, the inventors of the present application can stepwise control the moving speed of an air cylinder (piston) incorporated in an external pneumatic device in one stroke by a simple configuration without using a shock absorber. We have developed a speed controller with a cushioning function (see Patent Document 2: Japanese Patent Application Laid-Open No. 2014-055631).

Here, when the moving speed in one stroke of the air cylinder (piston) of the external pneumatic device is controlled stepwise by using the speed controller with cushion function, the speed specified by the switching point of the gas flow rate passing through is used. It is important to stabilize the switching point. For example, if the speed switching point is delayed, the cushion does not function until the stroke end of the air cylinder (piston), and a large impact may occur.

As a result of diligent research by the inventors of the present application, in the conventional speed controller with a cushion function, when the use is stopped for a certain period of time and then restarted, the main valve or the main valve equivalent member is stuck and restarted. The problem that the flow rate switching point, that is, the speed switching point may be delayed during the subsequent initial stroke has been clarified.

The present invention has been made in view of the above circumstances, and is configured to be used by being connected to an external pneumatic device, and the flow rate of the passing gas can be controlled stepwise, and after the use is stopped for a certain period of time. It is an object of the present invention to provide a switching valve capable of preventing a delay in the switching point of the flow rate when restarting.

As an embodiment, the problem is solved by a solution means as disclosed below.

The disclosed switching valve is tubular and has a sleeve having a supply port, a first exhaust port, a second exhaust port, a pilot supply port, and an open port, which are formed to communicate with each other inside and outside, and inside the sleeve. A first flow path that communicates the pilot supply port and the open port so as to pass through the sleeve, the supply port and the open A second flow path that communicates with the port, a third flow path that communicates the supply port and the first exhaust port, and a fourth flow path that communicates the supply port and the second exhaust port are provided. A first on-off valve that opens and closes the first flow path, a second on-off valve that opens and closes the second flow path, and a third on-off valve that opens and closes the third flow path are provided. The first on-off valve, the second on-off valve, and the third on-off valve are all provided with one of the valve body and the valve seat integrally or separately with the sleeve, and the other is integrally or separately with the main valve. In the first on-off valve and the second on-off valve, the valve body and the valve seat are arranged so as to be in contact with each other in a direction parallel to the moving direction of the main valve. When the pressure of the pilot supply air supplied to the pilot supply port is larger than the predetermined pressure, the main valve is moved toward the first end portion in the sleeve, and the first on-off valve and the first on-off valve and the first on-off valve are in a state of being moved to the first end side. 2 When the on-off valve is closed and the third on-off valve is opened and the pressure of the pilot supply air supplied to the pilot supply port is smaller than the predetermined pressure, the main valve is the second in the sleeve. It is characterized by having a configuration in which the first on-off valve and the second on-off valve are opened and the third on-off valve is closed in a state of being moved to the end side.

According to the disclosed switching valve, the flow rate of the passing gas can be controlled stepwise when connected to an external pneumatic device and used. Further, it is possible to prevent a delay in the flow rate switching point when the use is stopped for a certain period of time and then restarted.

It is a schematic diagram which shows the structural example of the switching valve which concerns on embodiment of this invention, and is also the operation explanatory drawing. It is a schematic diagram which shows the structural example of the switching valve which concerns on embodiment of this invention, and is also the operation explanatory drawing. It is a schematic diagram which shows the structural example of the switching valve which concerns on embodiment of this invention, and is also the operation explanatory drawing. It is a circuit diagram which shows the example of the case where the switching valve which concerns on embodiment of this invention is connected to the external pneumatic equipment. It is explanatory drawing (experimental data by a conventional mechanism) for demonstrating the problem which the switching valve which concerns on embodiment of this invention tries to solve. It is explanatory drawing (experimental data by the switching valve which concerns on embodiment of this invention) for demonstrating the effect achieved by the switching valve which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 3 are front sectional views (schematic views) showing a configuration example of the switching valve 1 according to the present embodiment, and also serve as an operation explanatory view. In all the drawings for explaining the embodiment, the members having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.

As an example, the switching valve 1 according to the present embodiment is exhausted (by the movement of a piston) of a driven air cylinder (hereinafter, simply referred to as “air cylinder”) C incorporated in an external pneumatic device constituting an automatic equipment line or the like. It is placed (connected) in a flow path through which compressed air of a predetermined pressure to be discharged) and controls the operating speed of the air cylinder C stepwise (for example, in two steps of high speed and low speed). Etc. are assumed.

As shown in FIGS. 1 to 3, the switching valve 1 moves in the axial direction (direction along the central axis S) in the tubular (for example, substantially cylindrical) sleeve 10 having a space portion at the center in the radial direction. It is configured to include a possibly disposed main valve 50. As the constituent material of the switching valve 1, a resin material (for example, POM, PBT, etc.) or a metal material (for example, POM, PBT, etc.) or a metal material (for example, POM, PBT, etc.) or a metal material (for example, POM, PBT, etc.) and metal materials (for example, POM, PBT, etc.) and metal materials (for example, POM, PBT, etc.) and metal materials (for example, POM, PBT, etc.) and metal materials (for example, POM, PBT, etc.) and metal materials (for example, POM, PBT, etc.) and metal materials (for example, POM, PBT, etc.) and metal materials (for example, POM, PBT, etc.) and metal materials (for example, POM, PBT, etc.) are used depending on the usage conditions, except for the portion where rubber, elastomer, etc. such as the sealing member described later are used. (Stainless alloy, aluminum alloy, brass, etc.) are appropriately used.

The sleeve 10 according to the present embodiment has a tubular shape (as an example) having a space portion in the radial center in the inner cylinder portion of the tubular main sleeve 12 having a space portion in the radial center (as an example). The first guide sleeve 14 having a substantially cylindrical shape and the second guide sleeve 16 having a cylindrical shape (for example, a substantially cylindrical shape) having a space in the radial center are the sealing members 18A, 18B, and 18C (example), respectively. An O-ring made of rubber, an elastomer, or the like is interposed in the structure. Therefore, the main valve 50 that moves in the sleeve 10 in the axial direction is more specifically configured to move in the first guide sleeve 14 and the second guide sleeve 16 (that is, in each space portion) in the axial direction. It has become. However, the configuration of the sleeve 10 is not limited to the above, and as a modification, a configuration in which the entire sleeve 10 is integrally formed, a configuration in which the first guide sleeve 14 and the second guide sleeve 16 are integrally formed, and the like are also used. Good (both not shown).

The sleeve 10 communicates inside and outside the tubular portion (that is, communicates inside and outside the entire fitted main sleeve 12, the first guide sleeve 14, and the second guide sleeve 16). The following ports with openings are provided. Specifically, a supply port 20, a first exhaust port 22, a second exhaust port 24, a pilot supply port 26, and an open port 28 are provided.

Further, for each of these ports, the following flow paths configured to pass between the inner cylinder portion of the sleeve 10 and the outer peripheral portion of the main valve 50 are provided (to avoid complication in the figure). Therefore, it is displayed in FIG. 2). Specifically, the first flow path 31 that communicates the pilot supply port 26 and the open port 28, the second flow path 32 that communicates the supply port 20 and the open port 28, and the supply port 20 and the first exhaust port 22. A third flow path 33 that communicates with the supply port 20 and a fourth flow path 34 that communicates the supply port 20 and the second exhaust port 24 are provided.

Further, a first on-off valve 41 for opening and closing the first flow path 31, a second on-off valve 42 for opening and closing the second flow path 32, and a third on-off valve 43 for opening and closing the third flow path 33 are provided. (Shown in FIGS. 2 and 3 to avoid complication of the figure).

In the above-mentioned first on-off valve 41, a valve body 41a formed separately by using rubber, an elastomer or the like is provided on the main valve 50, and the valve seat 41b is a sleeve 10 (in the present embodiment, the first on-off valve 41). It is provided integrally with the guide sleeve 14) (may be a separate body). As a modification, a configuration in which the valve body 41a is arranged on the sleeve 10 and the valve seat 41b is arranged on the main valve 50 is also conceivable (not shown).

In the same manner as this, in the second on-off valve 42, a valve body 42a formed separately by using rubber, an elastomer or the like is provided on the main valve 50, and the valve seat 42b is a sleeve 10 (in the present embodiment). Is integrally provided (may be a separate body) with the first guide sleeve 14). As a modification, a configuration in which the valve body 42a is arranged on the sleeve 10 and the valve seat 42b is arranged on the main valve 50 is also conceivable (not shown). Further, in the third on-off valve 43, a valve body 43a formed separately by using rubber, an elastomer or the like is provided on the main valve 50, and the valve seat 43b is a sleeve 10 (in the present embodiment, the first one). It is provided integrally with the guide sleeve 14) (may be a separate body). As a modification, a configuration in which the valve body 43a is arranged on the sleeve 10 and the valve seat 43b is arranged on the main valve 50 is also conceivable (not shown).

In the present embodiment, the valve body 41a of the first on-off valve 41 and the valve body 42a of the second on-off valve 42 are provided on the packing member 40 having an integrated structure, and the packing member 40 is used on the main valve 50. It is configured to be fitted on the outer peripheral portion. According to this, the number of parts can be reduced and the cost can be reduced. However, the present invention is not limited to this configuration, and the valve body 41a and the valve body 42a may be configured as separate bodies (not shown).

Here, a gas having a predetermined pressure (as an example, compressed air of about 0.5 MPa) is supplied (input) to the pilot supply port 26 as "pilot supply air". On the other hand, a gas having a predetermined pressure (as an example, compressed air of about 0.5 MPa) is supplied (input) to the supply port 20 as "supply air". Each gas (compressed air) can be, for example, configured to be supplied from a common source (for example, a compression pump or the like) (not shown). However, the present invention is not limited to this, and it may be configured to be supplied from different supply sources (for example, a compression pump or the like) (not shown).

The switching valve 1 having these configurations operates as follows. Specifically, when the pressure of the pilot supply air supplied to the pilot supply port 26 is larger than the predetermined pressure (hereinafter referred to as “first set pressure”), the main valve 50 is at the first end portion (hereinafter referred to as “first set pressure”) in the sleeve 10. The right end portion in the figure) is moved to the 10a side (the state shown in FIG. 1), the first on-off valve 41 and the second on-off valve 42 are "closed", and the third on-off valve 43 is "opened". And. On the other hand, when the pressure of the pilot supply air supplied to the pilot supply port 26 is smaller than the predetermined pressure (first set pressure), the main valve 50 is on the second end (left end in the figure) 10b side in the sleeve 10. (The state shown in FIG. 3), the first on-off valve 41 and the second on-off valve 42 are set to "open" and the third on-off valve 43 is set to "close". The state shown in FIG. 2 is in the process of transitioning from the state shown in FIG. 1 to the state shown in FIG. 3, or from the state shown in FIG. 3 to the state shown in FIG.

According to this, as an example, a circuit that exhausts the supply air supplied to the supply port 20 from both the first exhaust port 22 and the second exhaust port 24 and a circuit that exhausts the supply air from only the second exhaust port 24. , It is possible to switch. That is, since it is possible to switch the exhaust flow path, specifically, the third flow path 33 and the fourth flow path 34 and the fourth flow path 34, the cross-sectional area of the flow path (maximum). By switching the narrow portion), it is possible to switch the flow rate of the compressed air passing through. The third flow path 33 and the fourth flow path 34 are provided with a throttle valve 62 and a throttle valve 64, respectively (see FIG. 4), and the flow rate of compressed air passing through each flow path can be adjusted. It is composed.

Here, as an example of use (connection example) of the switching valve 1 according to the present embodiment, as shown in the circuit diagram of FIG. 4, the supply port 20 of the switching valve 1 is an air cylinder C incorporated in an external pneumatic device. Used by connecting to the exhaust port. In this case, when compressed air having a predetermined pressure (here, 0.5 MPa or the like described above) is supplied to the intake port of the air cylinder C and the piston moves, compressed air having the same pressure is sent out from the exhaust port. This compressed air is supplied (input) to the supply port 20 of the switching valve 1.

Therefore, the circuit that exhausts the supply air supplied to the supply port 20 by the switching valve 1 from both the first exhaust port 22 and the second exhaust port 24 and the circuit that exhausts the supply air from only the second exhaust port 24 , It becomes possible to obtain the action of switching. That is, it is possible to switch the cross-sectional area of the flow path for exhausting the external pneumatic device (air cylinder C) stepwise (here, two steps). As a result, the operating speed (axially moving speed) of the piston of the air cylinder C is switched from high-speed movement to low-speed movement, and it becomes possible to generate a cushion function. Therefore, since the speed immediately before the piston is stopped can be reduced, the impact at the time of stopping can be alleviated.

Further, as another example, the supply air supplied to the supply port 20 is exhausted only from the first exhaust port 22 by, for example, providing an on-off valve (not shown) for opening and closing the fourth flow path 34. It is possible to switch between the circuit to be exhausted and the circuit to exhaust from only the second exhaust port 24. Even with such a configuration, it is possible to generate a cushion function by performing the same action and effect as described above, that is, by switching the flow rate of the compressed air passing through.

By the way, as long as the cushion function is only generated when the piston of the air cylinder C is operated, it can be realized by a conventional speed controller with a cushion function, a spool type switching valve, or the like, as described above. However, in those conventional products, the internal main valve (or main valve equivalent member) sticks when restarting after stopping the use for a certain period of time, and the flow rate is switched at the first stroke after restarting. The problem that the point, that is, the speed switching point, is delayed has been clarified. Here, FIG. 5 shows the experimental results using the conventional mechanism. Two types of time are set from the suspension of use to the restart. Plot A1 is standard data during normal operation, plot A2 is data when the data is restarted after 10 minutes of suspension, and plot A3 is data when the data is restarted after 3 hours of suspension. In each case, the vertical axis is the pressure value of the pilot supply air, and the horizontal axis is the value of the response delay time when the main valve 50 responds (starts to move) in response to the pressure change of the pilot supply air. As is clear from this graph, the longer the suspension time, the longer the delay time until the main valve 50 responds (movement start point: point E in FIG. 5), that is, the main valve 50 is fixed. It can be seen that the degree increases.

In order to solve such a problem, the switching valve 1 according to the present embodiment has the following configuration. First, in the first on-off valve 41 and the second on-off valve 42, the valve body and the valve seat (specifically, the valve body 41a and the valve seat 41b, and the valve body 42a and the valve seat 42b). The main valve 50 is arranged so as to be in contact with and separated from the main valve 50 in a direction parallel to the moving direction (that is, the same as the direction parallel to the central axis S of the inner cylinder portion of the sleeve 10). According to the research by the inventors of the present application, it has been clarified that the sticking of the main valve, which is a problem, is caused by the generation of a close contact state due to the pressure contact between the valve body provided on each on-off valve and the corresponding valve seat. On the other hand, according to the above configuration, even if the valve body (here, 41a, 42a) and the corresponding valve seat (here, 41b, 42b) are in close contact with each other, a close contact state occurs. The close contact state can be easily eliminated, and the occurrence of sticking can be eliminated (or suppressed).

Here, FIG. 6 shows the experimental results using the switching valve 1 according to the present embodiment having the said configuration. Plot B1 is standard data during normal operation, and plot B2 is data when the data is restarted after being stopped for 3 hours. The indexes on the vertical axis and the horizontal axis are the same as those in FIG. As is clear from this graph, according to the switching valve 1 according to the present embodiment, it can be seen that the degree of sticking of the main valve 50 is almost zero (or extremely small) even if the use is stopped for a long time.

Further, as a modification, the valve seats 41b, 42b, 43b are formed by using a metal material or a resin material, and in all or a part of them, at the contact surface with the corresponding valve bodies 41a, 42a, 43a. The structure may be plated or greased to reduce the coefficient of friction of the surface. According to this, even if the valve body (here, 41a, 42a) and the corresponding valve seat (here, 41b, 42b) are in close contact with each other and a close contact state occurs, the close contact state can be easily eliminated. , The effect of eliminating (or suppressing) the occurrence of sticking can be further enhanced.

Further, in the switching valve 1 according to the present embodiment, the second flow path 32 (here, the position that is the narrowest portion between the inner cylinder portion of the first guide sleeve 14 and the outer peripheral portion of the main valve 50). It has a characteristic configuration that the minimum cross-sectional area is smaller than the minimum cross-sectional area of the first flow path 31 (here, the position downstream from the first on-off valve 41 and between the outlet of the open port 28). ing. If the minimum cross section of the second flow path 32 is larger than or equal to the minimum cross section of the first flow path 31, the compressed air supplied to the supply port 20 when the main valve 50 moves is piloted. It flows into the supply port 26 side, and the thrust generated by the pressure of the pilot supply air is increased more than the set value. As a result, there arises a problem that the main valve 50 is not stably switched at a desired timing.

To solve this problem, in the present embodiment, an open port 28 that opens the exhaust gas of the pilot supply air to the atmosphere is provided (details will be described later), and as described above, the minimum cross-sectional area of the second flow path 32 is the first. The problem can be solved by a configuration smaller than the minimum cross-sectional area of the flow path 31. That is, according to these configurations, when the main valve 50 is switched (moved) in the direction of opening the first on-off valve 41, the pilot supply air can be released to the atmosphere at once and supplied through the second flow path 32. The action of flowing to the port 20 side can be almost eliminated (or extremely small). Further, since the supply air flowing from the supply port 20 through the second flow path 32 can be passed to the open port 28 side instead of the pilot supply port 26 side, the thrust generated by the pressure of the pilot supply air is set or higher. It is possible to almost completely eliminate (or make it extremely small) the effect of increasing the pressure. Therefore, the movement of the main valve 50, that is, the switching can be stably performed at a desired timing. The switching timing can be set by the speed controller 66 (see FIG. 4).

As described above, in the present embodiment, the open port 28 is configured to open the flowing gas under atmospheric pressure. However, the configuration is not limited to this, and the same effect can be obtained even with a configuration in which the flowing gas is released under a minute pressure (for example, about 0.2 MPa or less).

Further, in the switching valve 1 according to the present embodiment, the urging member (for example, a coil spring or other spring member) 60 that urges the main valve 50 in the sleeve 10 in the direction of moving the main valve 50 to the second end portion 10b. Is further equipped. According to this, the movement operation of the main valve 50 can be assisted, and the posture of the main valve 50 can be stabilized when the supply air is not applied (or is small). The urging force of the urging member 60 (for example, the coil spring) is appropriately set depending on the size of the sleeve 10 and the main valve 50. As an example, an urging force of about 1N is generated at the time of assembling. Set.

In the case of a configuration including such a spring 60, the above-mentioned "first set pressure" is a conversion of the pressure of the supply air supplied to the supply port 20 and the urging force of the urging member 60 (for example, a coil spring). It is set as the pressure obtained by adding the pressure.

Here, as described above, the supply air (compressed air) supplied to the supply port 20 and the pilot supply air (compressed air) supplied to the pilot supply port 26 are configured to be supplied from a common supply source. (Note that the "supplied air" is supplied via the air cylinder C). Therefore, it is necessary to adjust the pressure of the pilot supply air so that it becomes larger than the first set pressure.

In this regard, in the main valve 50 according to the present embodiment, the diameter of the pressure receiving area of the pilot supply air supplied from the pilot supply port 26 (specifically, the diameter of the valve body 41a (contact position with the valve seat 41b)). The specified pressure receiving area) is larger than the pressure receiving area of the supply air supplied from the supply port 20 (specifically, the pressure receiving area defined by the diameter of the valve body 42a (contact position with the valve seat 42b)). It is configured to be. According to this configuration, the thrust that moves the main valve 50 toward the first end 10a by the pressure of the pilot supply air is the thrust that causes the main valve 50 to move to the second end by the pressure of the supply air and the urging force of the urging member 60. It can be set to be larger than the thrust to move in the 10b direction. As an example, in the usage mode in which the supply port 20 is connected to the exhaust port of the air cylinder C, the flow velocity of the exhaust gas becomes high and the pressure of the supply air becomes low, so that this effect is superimposed. By acting, the action of generating and maintaining a state in which the thrust due to the pressure of the pilot supply air is higher is enhanced.

As described above, according to the disclosed switching valve, the flow rate when exhausting the gas with a predetermined pressure supplied (input) to the supply port is controlled stepwise (here, two steps). It becomes possible to do. As an example, if it is configured to be connected to the exhaust port of an air cylinder built into an external pneumatic device, it will be moved at high speed for a while after the piston of the air cylinder starts moving to shorten the operating time. At the same time, it is possible to switch the moving speed from high speed to low speed at the set timing immediately before the piston stops. Therefore, it is possible to reduce the impact when the piston of the air cylinder is stopped without using a shock absorber.

Further, this switching valve can prevent a delay in the flow rate switching point due to the main valve sticking to the sleeve when the switching valve is restarted after being stopped for a certain period of time.

Needless to say, the present invention is not limited to the embodiments described above, and can be variously modified without departing from the present invention.

1 Switching valve 10 Sleeve 20 Supply port 22 1st exhaust port 24 2nd exhaust port 26 Pilot supply port 28 Open port 31 1st flow path 32 2nd flow path 33 3rd flow path 34 4th flow path 41 1st on-off valve 42 2nd on-off valve 43 3rd on-off valve 50 Main valve 60 Bouncer

Claims (6)

A sleeve that is cylindrical and has a supply port, a first exhaust port, a second exhaust port, a pilot supply port, and an open port that are open to communicate inside and outside.
A main valve, which is arranged so as to be movable in the axial direction in the sleeve, is provided.
A first flow path communicating the pilot supply port and the open port so as to pass through the sleeve, a second flow path communicating the supply port and the open port, and the supply port and the first exhaust. A first on-off valve that has a third flow path that communicates with the port and a fourth flow path that communicates the supply port and the second exhaust port, and that opens and closes the first flow path. A second on-off valve that opens and closes the second flow path and a third on-off valve that opens and closes the third flow path are provided.
The first on-off valve, the second on-off valve, and the third on-off valve are all provided with one of the valve body and the valve seat integrally or separately with the sleeve, and the other is integrally or separately with the main valve. It is provided on the body and
In the first on-off valve and the second on-off valve, the valve body and the valve seat are arranged so as to be in contact with each other in a direction parallel to the moving direction of the main valve.
When the pressure of the pilot supply air supplied to the pilot supply port is larger than the predetermined pressure, the main valve is moved toward the first end portion in the sleeve, and the first on-off valve and the second on-off valve and the second on-off valve are in a state of being moved to the first end side. When the on-off valve is closed and the third on-off valve is opened and the pressure of the pilot supply air supplied to the pilot supply port is smaller than the predetermined pressure, the main valve is the second end in the sleeve. A switching valve having a configuration in which the first on-off valve and the second on-off valve are opened and the third on-off valve is closed in a state of being moved to the portion side. The switching valve according to claim 1, wherein the minimum cross-sectional area of the second flow path is configured to be smaller than the minimum cross-sectional area of the first flow path. The switching valve according to claim 1 or 2, further comprising an urging member for urging the main valve in the sleeve in a direction of moving the main valve to the second end portion. The switching valve according to claim 3, wherein the predetermined pressure is a pressure obtained by adding the pressure of the supply air supplied to the supply port and the pressure converted into the urging force of the urging member. One of claims 1 to 4, wherein the valve seat is formed by using a metal material or a resin material, and is plated or greased on a contact surface with the valve body. The switching valve described. The switching valve according to any one of claims 1 to 5, wherein the supply port is connected to an exhaust port of an air cylinder incorporated in an external pneumatic device.

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