JPH10332032A - Pilot type solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily change setting between a self holding type and a self resetting type, prevent non-specific faulty operation under setting of each type. SOLUTION: In two pilot valves 44, 45, supply of a pilot pressure to a first/ second pressure chamber 11, 12 is switched. A first/second piston 18, 19 provided in each pressure chamber 11, 12 includes a pressure receiving surface 18a, 19a of equal size. A pressure receiving surface 29a of a third piston 29 provided in a third pressure chamber 22 of the piston 18 is smaller than the other pressure receiving surface 18a, 19a. By the piston 19, one inner wall of a peripheral groove 23 communicated with the pressure chamber 22 is formed larger than the other inner wall. Supply of a pilot pressure to both the pressure chambers 12, 22, by a manually operated valve 5, is switched to a first or second mode. In the first mode, in order to press a spool valve 4 by the piston 29, to the peripheral groove 23 and the pressure chamber 22, the pilot pressure is always supplied. In the second mode, in order to press the spool valve 4 by the piston 19, supply of the pilot pressure to the pressure chamber 12 is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot type solenoid valve which switches a fluid flow path by driving a spool valve by supplying a pilot pressure.
More particularly, the present invention relates to a pilot solenoid valve that selectively switches between a single solenoid type (self-returning type) operation mode and a double solenoid type (self-holding type) operation mode.

[0002]

2. Description of the Related Art Conventionally, this type of solenoid valve has a switching valve section including a spool valve, and a pilot type actuator section for indirectly moving the spool valve by air pressure (pilot pressure). The actuator section includes an electrically driven pilot valve. By controlling the pilot valve, the supply of the pilot pressure to the switching valve portion is switched, and the spool valve is driven.

[0003] As a pilot type actuator,
There are a single solenoid type and a double solenoid type.
The single solenoid type has one pilot valve, and the double solenoid type has two pilot valves.

In a solenoid valve having a single solenoid type actuator, a pilot pressure is always supplied to one end of a spool valve. One end of the spool valve is pressed by this pilot pressure, and the spool valve is held at its return position. When the pilot valve is turned on, pilot pressure is also supplied to the other end of the spool valve, and the spool valve is pressed from both ends. Here, since the pressure receiving areas of the pistons provided at both ends of the spool valve are different, the spool valve moves forward from its return position based on a difference in thrust generated between the pistons. When the pilot valve is turned off, one end of the spool valve is opened to the atmosphere, and the spool valve returns to its original position. That is, in this type of solenoid valve, a self-return type operation mode in which the spool valve can be returned to the original position by turning off the pilot valve is obtained.

In an electromagnetic valve having a double solenoid type actuator unit, the supply of pilot pressure to the switching valve unit is switched by turning on / off each pilot valve, and the spool valve reciprocates. In this type of solenoid valve, even if each pilot valve is turned off and one end of the spool valve is opened to the atmosphere, the spool valve does not return to the original position. In this case, the spool valve is held at the position where both pilot valves were turned off. That is, with this type of solenoid valve, a self-holding operation mode in which the spool valve can be held at a certain position as the pilot valve is turned off is obtained.

The structure and operation of the single solenoid type solenoid valve and the double solenoid type solenoid valve are different from each other as described above. For this reason, in order to properly use the operation mode of each system in a certain pneumatic circuit, it is necessary to select a required solenoid valve from two types of solenoid valves. Or,
In a certain pneumatic circuit, when a single solenoid type solenoid valve was initially used to obtain a self-return type operation mode, when it became necessary to obtain a self-holding type operation mode, a single solenoid type electromagnetic valve was used. The valve needs to be replaced with a double solenoid type solenoid valve. This replacement requires a lot of time and effort, and the workability is not good.

Therefore, in order to save such labor, there has been proposed an electromagnetic valve having both a self-returning type and a self-holding type of operation and selectively exerting them. Japanese Patent Application Laid-Open No. 7-198,054 discloses an example of this type of dual-purpose pilot solenoid valve.

FIG. 9 shows an electromagnetic valve 71 having the same basic configuration as the electromagnetic valve of the above publication. The solenoid valve 71 includes an actuator section 72 including first and second solenoids 75 and 76, and a switching valve section 74 including a spool valve 73. Each solenoid 75, 76 has a corresponding first or second
Are driven, respectively. The switching valve section 74 has an air supply port 79, exhaust ports 80 and 81, and output ports 82 and 83. The spool valve 73 has a large-diameter piston 84 and a small-diameter piston 85 at both ends. The large-diameter piston 84 is accommodated in the corresponding large-diameter chamber 86, and the small-diameter piston 85 is accommodated in the corresponding small-diameter chamber 87. Two open ends of the air supply passage 88 communicating with the air supply port 79 are selectively opened and closed by first and second valve bodies 77 and 78. By selectively opening and closing the valve bodies 77 and 78, the supply of the pilot pressure to the chambers 86 and 87 is switched. As a result, the spool valve 73 is reciprocated, and the supply air flow and the exhaust air flow are switched between the ports 79 to 83, respectively.

The manual valve 89 provided in the switching valve section 74 is
It is operated to selectively and directly open and close the space between the air supply passage 88 and the small diameter chamber 87. With this manual valve 89,
By shutting off the space between the air supply passage 88 and the small diameter chamber 87, the solenoid valve 71 is set to a self-holding operation mode.
In this setting, the pilot pressure is supplied to the large-diameter chamber 86 or the small-diameter chamber 87 by selectively opening only one of the two valve bodies 77 and 78, and the spool valve 73 is driven. Both the valve bodies 77 and 78 are closed, and the supply of the pilot pressure to the large-diameter chamber 86 and the small-diameter chamber 87 is shut off, so that the spool valve 73 is held at the stop position. The solenoid valve 71 is set to a self-return type by opening the space between the air supply passage 88 and the small diameter chamber 87 by the manual valve 89. In this setting, the pilot pressure is always supplied to the small diameter chamber 87. Therefore, even if both the valve bodies 77 and 78 are closed, the supply of the pilot pressure to the small diameter chamber 87 is not interrupted. By the pressing force, the spool valve 7
3 will be located at the return position shown in FIG.

[0010]

However, in the conventional dual-purpose pilot-type solenoid valve 71, both solenoids 75 and 76 are erroneously energized when the solenoid valve 71 is set to the self-holding type. When both valve bodies 7
7, 78 open both open ends of the air supply passage 88. Thus, the pilot pressure is supplied to both the large diameter chamber 86 and the small diameter chamber 87. In this case, due to the difference in diameter between the large-diameter piston 84 and the small-diameter piston 85, the thrust of the large-diameter piston 84 by the pilot pressure exceeds the thrust of the small-diameter piston 85, and as a result, the spool valve 7
3 will move. Thereby, the solenoid valve 71
May cause malfunction.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to make it possible to easily change a setting between a self-holding type and a self-returning type. It is another object of the present invention to provide a pilot type solenoid valve which does not cause an unspecified malfunction even when the pilot pressure is supplied to both ends of the spool valve at the same time under the above setting.

A second object of the present invention is to provide, in addition to the first object, a good responsiveness under the setting of each model while ensuring appropriate operation modes of a self-holding type and a self-return type. An object of the present invention is to provide a pilot-type solenoid valve capable of securing the pilot-type solenoid valve.

[0013]

According to a first aspect of the present invention, there is provided a spool valve for switching a flow path of a fluid, and both ends of the spool valve for driving the spool valve. A first pressure chamber and a second pressure chamber
And a pilot valve for controlling the pilot pressure supplied to the pressurizing chamber (allowing or restricting the supply of the pilot pressure to the first and second pressurizing chambers). Has a first piston corresponding to the first pressurizing chamber and a second piston corresponding to the second pressurizing chamber, and the first and second pistons have pressure receiving surfaces of the same size as each other. And the second piston slidably accommodates the third piston in a third pressurizing chamber therein,
The pressure receiving surface of the third piston is smaller than the pressure receiving surface of the second piston, and the second piston has an outer circumferential groove communicating with the third pressurizing chamber, and the outer circumferential groove moves the second piston. A first inner wall and a second inner wall opposing each other in the direction, wherein the second inner wall is disposed closer to the spool valve than the first inner wall, and has a larger pressure receiving area than the first inner wall; In order to press one end of a spool valve by a third piston, a first mode is provided in which the second pressure chamber is communicated with the atmosphere and a pilot pressure is constantly supplied to the third pressure chamber via an outer circumferential groove. A second piston for pressing one end of the spool valve by the second piston, allowing the supply of the pilot pressure to the second pressurizing chamber, and allowing the outer peripheral groove and the third pressurizing chamber to communicate with the atmosphere. The mode of supplying the pilot pressure is switched between And purpose that a switching means.

According to the configuration of the first invention, the supply of the pilot pressure to the second pressurizing chamber is permitted by switching the supply mode of the pilot pressure to the second mode,
The outer peripheral groove and the third pressure chamber are communicated with the atmosphere. Therefore, when the pilot pressure is supplied to the second pressurizing chamber by the pilot valve, the second piston receives the pilot pressure on its pressure receiving surface, generates thrust, and presses the spool valve. Here, since the size of the pressure receiving surface of the second piston and the size of the pressure receiving surface of the first piston are the same,
The thrust generated by the second piston is equal to the thrust generated by the second piston.

Here, the pilot pressure is selectively supplied to the first or second pressurizing chamber by the pilot valve, and the spool valve is selectively reciprocated by the pressing of the first or second piston. And the flow path of the fluid in the solenoid valve is switched. Further, the supply of the pilot pressure to the first and second pressurizing chambers is both shut off by the pilot valve, so that the first and second pistons no longer press the spool valve, and the spool valve is Is held in the position. That is, a self-holding operation mode can be obtained with this solenoid valve. On the other hand, even when the pilot pressure is simultaneously supplied to the first and second pressurizing chambers by mistake, the first and second pistons generate the same thrusts in opposite directions to press the spool valve, and the spool valve Is held in the current position.
Therefore, even if the pilot pressure is simultaneously supplied to the first and second pressurizing chambers due to the malfunction of the pilot valve, the spool valve does not erroneously move in an unspecified direction. Are not accidentally switched.

On the other hand, when the pilot pressure supply mode is switched to the first mode by the switching means,
The second pressurizing chamber is communicated with the atmosphere, and the pilot pressure is constantly supplied to the third pressurizing chamber via the outer circumferential groove. Here, thrust is generated on the first and second inner walls of the outer circumferential groove by the pilot pressure, but the pressure receiving area of the second inner wall is larger than that of the first inner wall. For this reason, the thrust of the second inner wall exceeds the thrust of the first inner wall, and the second piston moves in the direction away from the spool valve based on the difference in the thrust. And the third
Receives the pilot pressure supplied to the third pressurizing chamber on its pressure receiving surface, generates a thrust, and presses the spool valve. Here, since the pressure receiving surface of the first piston is larger than that of the third piston, the thrust of the first piston is larger than the thrust of the third piston.

Here, when the pilot pressure is supplied to the first pressurizing chamber by the pilot valve, the spool valve causes the thrust between the thrust generated by the first piston and the thrust generated by the third piston. It is pushed based on the difference and moves forward,
The flow path of the fluid in the solenoid valve is switched. The supply of the pilot pressure to the first pressurizing chamber is interrupted by the pilot valve, so that the first piston does not press the spool valve. Then, the spool valve is pressed only by the third piston, moves backward in the direction opposite to the forward movement based on the thrust difference, and returns to the terminal position. That is, a self-return type operation mode can be obtained with the solenoid valve. Therefore, even if pilot pressure is simultaneously supplied to the first and second pressurizing chambers due to a malfunction of the pilot valve, the flow path in the solenoid valve is erroneously switched because the spool valve moves in a predetermined direction. Nothing.

According to a second aspect of the present invention, in order to achieve the above object, in the configuration of the first aspect, the solenoid valve includes a bore for slidably housing the second piston, and The second piston has a packing disposed on the outer periphery thereof near the first inner wall, the packing seals between the outer peripheral groove and the outside, and the bore has a step portion having a smaller diameter than other portions. When the second piston approaches the bottom of the bore, the packing rides on the step and is compressed, and when the second piston moves away from the bottom of the bore,
The packing is detached from the step and the compression is released.

According to the configuration of the second aspect, when the second piston approaches the bottom surface of the bore, the packing rides on (contacts) the step and is compressed. For this reason, the sealing effect of the packing is obtained, the leakage of the pilot pressure from the outer peripheral groove is suppressed, and the pilot pressure supplied to the outer peripheral groove and the third pressurizing chamber effectively acts on the second piston. Therefore, the malfunction of the second piston in the self-return type operation mode is suppressed, and the stable operation of the solenoid valve is ensured.

When the second piston moves away from the bottom surface of the bore, the packing separates from the step and the compression of the packing is released. For this reason, the sliding resistance between the packing and the bore in the self-holding operation mode is reduced, and the movement of the second piston becomes smooth. Therefore, the response of the movement of the spool valve is enhanced, and the smooth operation of the solenoid valve is ensured. Here, originally, the packing becomes unnecessary structurally because the sliding resistance of the second piston against the bore is increased only in the self-holding operation mode. However, in the present invention, the compression of the packing is released in the above-described self-holding operation mode, so that the packing is not related to increasing the sliding resistance between the packing and the bore.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pilot solenoid valve according to the present invention will be described below in detail with reference to FIGS.

As shown in FIG. 1, the pilot type solenoid valve 1 has a switching valve portion 2 and an actuator portion 3 provided on one side thereof. The switching valve section 2 has a spool valve 4 for switching a fluid (gas) flow path. The switching valve section 2 has a manual valve 5 provided to be exposed to the outside. The actuator section 3 is electrically controlled to drive the spool valve 4.

The switching valve section 2 includes a spool housing 6, a joint housing 7, and a manifold block 8. The spool housing 6 accommodates the spool valve 4 in a reciprocating manner. The spool valve 4 moves with a predetermined stroke in the axial direction. The spool housing 6 has a spool valve 4
Has a first bore 9 and a second bore 10 provided at both ends. The first bore 9 has a bottomed shape and forms a first pressurizing chamber 11. The second bore 10 also has a bottomed shape and forms a second pressurizing chamber 12. The spool housing 6 has one air supply port 13, first and second output ports 14, 15, and a pair of exhaust ports 16, 17.

As shown in FIGS.
Are a plurality of valve portions 4a spaced apart from each other on the axis thereof.
Having. The outer diameter of each valve portion 4a is larger than that of the shaft.
The spool valve 4 has a first piston 18 provided at both ends thereof corresponding to the first pressurizing chamber 11, and a second piston 19 provided corresponding to the second pressurizing chamber 12. . The first piston 18 has a substantially cylindrical shape and is provided integrally with the spool valve 4. This piston 18 has its pressure receiving surface 18
Receive pilot pressure at a. The first piston 18 has an annular packing 20 on its outer periphery. This packing 2
Reference numeral 0 has a V-shaped cross section, and seals the space between the first pressurizing chamber 11 and the outside thereof (on the back side of the first piston 18).
The packing 20 slides along the inner peripheral surface of the first bore 9 as the first piston 18 moves.

The second piston 19 is provided separately from the spool valve 4. This piston 19 has a pressure receiving surface 19a.
To receive pilot pressure. The two pressure receiving surfaces 18a, 1
9a are the same in size. Here, the pressure receiving surface 18a of the first piston 18 means an area corresponding to the outer diameter of the piston 18, and the portion occupied by the packing 20 in FIGS. 1, 3, and 8 is also included in the pressure receiving surface 18a. The first and second pistons 19 each have a bottomed cylindrical shape and have a third bore 21 therein. This bore 21 has a bottomed shape,
The third pressure chamber 22 is configured. One end of the third bore 21 opens toward the spool valve 4.

The second piston 19 has an outer peripheral groove 2 on its outer periphery.
3 The outer peripheral groove 23 communicates with the third pressure chamber 22 via the hole 24. As shown in FIGS.
The outer peripheral groove 23 includes first and second inner walls 25 and 26 which are spaced apart from each other and opposed in the moving direction of the second piston 19. The first inner wall 25 is arranged closer to the spool valve 4 than the second inner wall 26 is. The second inner wall 26 has a larger pressure receiving area in the spool axial direction than the first inner wall 25. Second
Of the first and second packings 2
7,28. The two packings 27 and 28 are formed in an annular shape, and are in contact with the inner peripheral surface of the second bore 10. The first packing 27 has a substantially V-shaped cross section, is disposed close to the first inner wall 25, and has an outer peripheral groove 23 and an outer part thereof (the second piston 19).
Back side). The second packing 28 has a flat shape. The packing 28 can seal the pressure in both directions, whereas the packing 27 seals only the pressure in one direction. The packing 28 is arranged close to the second inner wall 26 and seals between the outer peripheral groove 23 and the second pressurizing chamber 12. These packings 27, 28
Slides along the inner peripheral surface of the second bore 10 with the movement of the second piston 19.

The spool valve 4 further has a third piston 29 provided corresponding to the third pressurizing chamber 22. The third piston 29 moves along the same axis as the second piston 19. The third piston 29 is provided integrally with the spool valve 4. The third piston 29 has its pressure receiving surface 29
Receive pilot pressure at a. This pressure receiving surface 29 a is smaller than the pressure receiving surface 19 a of the second piston 19. The third piston 29 has an annular packing 30 on its outer periphery.
The packing 30 has a substantially V-shaped cross section, and seals between the third pressurizing chamber 22 and the outside thereof (on the back side of the third piston 29). This packing 30 is used for the third piston 2
9 moves along the inner peripheral surface of the third bore 21. Here, the pressure receiving surface 29a of the third piston 29 is
It means an area corresponding to the outer diameter of the piston 29, and the portion occupied by the packing 30 in FIGS.

As shown in FIGS. 4, 5, and 7, the second bore 1
0 includes a step portion 31 having a smaller inner diameter than other portions on a part of its inner peripheral surface. This step 31 is the first packing 2
7 are arranged. As shown in FIGS.
Is arranged close to the bottom surface 10a of the second bore 10, so that the first packing 27
It rides on 1 and is compressed based on its own elasticity. On the other hand, as shown in FIG. 5, when the second piston 19 moves in the direction away from the bottom surface 10a, the first packing 27 separates from the step portion 31 and is released from compression.

FIGS. 3 and 5 exemplify differences in design dimensions for the pistons 18, 19, 29 and the like. As shown in FIG. 3, in this embodiment, the outer diameter D1 of the first piston 18 is “φ8.9 mm”, and the outer diameter D2 of the second piston 19 near the second packing 28 is "Φ8.
9 mm ", the first packing 2 of the piston 19
The outer diameter D3 near 7 is set to “φ8.2 mm”, and the outer diameter D4 of the third piston 29 is set to “φ5.6 mm”. As shown in FIG. 5, in this embodiment, the dimensional difference H between the inner peripheral surface 10b of the bore 10 corresponding to the moving range of the first packing 27 adjacent to the step 31 and the step 31 is “ 0.1 mm ". When the first packing 27 reaches the inner peripheral surface 10b, no compressive force acts on the packing 27, and the packing 27 has a dimensional relationship that does not seal the pressing force.

Each of the pistons 18, 19, 29 applies a pilot pressure supplied to the corresponding pressurizing chamber 11, 12, 22 to drive the spool valve 4 in its axial direction. The thrust is received at 29a, and the spool valve 4 is pressed. When the spool valve 4 is driven by this pressing, the flow path of the gas supplied to the air supply port 13 is switched between the first output port 14 and the second output port 15. At the same time, the flow path of the gas introduced into the second or first output port 15, 14 is switched between the exhaust ports 16, 17.

As shown in FIG. 1, the joint housing 7 has two pipe joints 32 and 33 and a main air supply passage 34. One joint 32 communicates with the first output port 14,
The other joint 33 communicates with the second output port 15. The main air supply passage 34 communicates with the air supply port 13. The compressed air whose flow path is switched by the solenoid valve 1 flows through the main air supply passage 34.

The manifold block 8 includes the main exhaust passage 3
5, a pilot air supply passage 36 and a manual valve 5 are provided. The main exhaust passage 35 is provided at each exhaust port 1 of the spool housing 6.
The gas discharged from each of the exhaust ports 16 and 17 is discharged to the outside of the solenoid valve 1. Compressed air supplied as pilot pressure to each of the pressurizing chambers 11, 12, and 22 flows through the pilot air supply passage.

As shown in FIGS. 1, 2, and 6, the manual valve 5 has a long axis shape and is operated to switch the supply of the pilot pressure to the second and third pressurizing chambers 12 and 22. The manifold block 8 has a valve hole 37 that opens upward. The manual valve 5 is incorporated in the valve hole 37 so as to be vertically movable and rotatable. A spring 38 for urging the manual valve 5 upward is provided at the bottom of the valve hole 37. Manual valve 5 is head 5
a, a shaft 5b having a smaller diameter than the head 5a, and a head 5a
The first valve portion 5c and the second valve portion 5c provided between
And a second valve portion 5e provided at the lower end of the shaft portion 5b. Each valve part 5c, 5d, 5e is a shaft part 5b.
Larger diameter than

As shown in FIG. 1, the manual valve 5 is arranged at an “inoperative position” where the upper end thereof coincides with the open end of the valve hole 37. When the manual valve 5 is pressed downward by a jig or the like against the urging force of the spring 38, as shown in FIG. In this operating position, the manual valve 5 is held in position by being rotated in the circumferential direction and engaging with a pin (not shown).
In this way, the manual valve 5 is switched between the inactive position and the active position.

In the manifold block 8, the pilot air supply passage 36 communicates with the bottom of the valve hole 37. The block 8 includes a first chamber passage 39 communicating with the first pressurizing chamber 11.
A second chamber passage 40 communicating with the second pressurizing chamber 12;
It has a third chamber passage 41 communicating with the third pressurizing chamber 22, an atmosphere passage 42 communicating with the atmosphere, and a supply / exhaust passage 43 communicating with the actuator unit 3. Supply / exhaust passage 43, second
The third chamber passages 40 and 41 and the atmosphere passage 42 communicate with the upper portion of the valve hole 37, respectively. In this embodiment, the manual valve 5, the valve hole 37, and each of the passages 36, 40 to 43 constitute the switching means of the present invention.

As shown in FIGS. 1 and 2, when the manual valve 5 is located at the non-operating position, the second chamber passage 40 communicates with the supply / exhaust passage 43 through the valve hole 37. At this time, the third chamber passage 41 communicates with the atmosphere passage 42 via the valve hole 37. The third valve portion 5e allows the pilot air supply passage 36
And the upper part of the valve hole 37 is shut off. Accordingly, the pilot pressure is supplied to the second pressurizing chamber 12 depending on the control of the actuator unit 3, and the supply of the pilot pressure to the third pressurizing chamber 22 is cut off. This manner of supplying the pilot pressure corresponds to the second aspect of the present invention. That is, in the second embodiment, since the spool valve 4 is pressed by the thrust of the second piston 19, the second pressure chamber 12
Is supplied, and the outer peripheral groove 23 and the third pressurizing chamber 22 are communicated with the atmosphere.

As shown in FIG. 6, when the manual valve 5 is located at the operating position, the second chamber passage 40 communicates with the atmosphere through the valve hole 37. The second valve section 5d shuts off the space between the third chamber passage 41 and the atmosphere passage 42. The pilot air supply passage 36 is connected to the third chamber passage 41 through the valve hole 37.
Communicate with As a result, the pilot pressure is forcibly supplied to the third pressurizing chamber 22 at all times, and the supply of the pilot pressure to the second pressurizing chamber 12 is shut off. This manner of supplying the pilot pressure corresponds to the first aspect of the present invention. That is, in the first embodiment, since the spool valve 4 is pressed by the thrust of the third piston 29, the supply of the pilot pressure to the second pressurizing chamber 12 is interrupted. Chamber 12 is communicated to the atmosphere. together,
The pilot pressure is constantly supplied to the third pressurizing chamber 22 through the outer peripheral groove 23.

As shown in FIG. 1, the actuator section 3 is of a double solenoid type, and is used for the first and second pilot valves 44 and 45 which are electrically controlled, and for both pilot valves 44 and 45. And a pilot exhaust passage 47. First pilot valve 4
4 is a pilot pressure supply to the first pressurizing chamber 11,
Switching between pilot pressure discharge from the same chamber 11 is performed. The second pilot valve 45 switches between supplying the pilot pressure to the second pressurizing chamber 12 and discharging the pilot pressure from the same chamber 12.

The first pilot valve 44 has a first solenoid 48, a first core 49, a first plunger 50, and a first valve body 51. The second pilot valve 45 is
, A second core 53, a second plunger 54, and a second valve body 55. Each plunger 50,
54 is urged by a return spring 56. The first valve body 51 moves in conjunction with the first plunger 50. Second
The valve element 55 moves in conjunction with the second plunger 54.

The valve casing 46 has first and second air supply valve seats 57, 58 corresponding to the respective valve bodies 51, 55. Each air supply valve seat 57, 58 has an air supply hole 57a, 58a, respectively. The valve casing 46 has first and second exhaust valve seats 59, 60 corresponding to the respective valve bodies 51, 55. Each exhaust valve seat 59, 60 has exhaust holes 59a, 60a, respectively.

The valve casing 46 has first and second pilot output ports 61 and 62, a pilot air supply chamber 63, and a pilot exhaust chamber 64. Both air supply holes 57a, 5
8 a communicates with the pilot air supply passage 36 via the pilot air supply chamber 53. Both exhaust holes 59a and 60a communicate with the pilot exhaust passage 47 through the pilot exhaust chamber 64. The first pilot output port 61 is connected to the supply / exhaust passage 6.
5 communicates with the first chamber passage 39. The second pilot output port 62 communicates with the second chamber passage 40 via the supply / exhaust passage 43 and the valve hole 37.

Here, when the first solenoid 48 is excited (turned on), the first plunger 50 moves and the first valve body 51 opens the air supply hole 57a and the exhaust hole 5a.
Close 9a. Thereby, the pilot pressure introduced from the pilot air supply passage 36 into the pilot air supply chamber 63 becomes
From the first pilot output port 61 to each passage 65, 39
Is supplied to the first pressurizing chamber 11 through

When the second solenoid 52 is excited (turned on), the second valve body 55 opens the air supply hole 58a and closes the exhaust hole 60a. Thus, the pilot pressure introduced from the pilot supply passage 36 into the pilot supply chamber 63 is supplied from the second pilot output port 62 to the second pressurization chamber 12 through the passages 43 and 40.
The solenoids 48 and 52 are on / off controlled by a predetermined controller (not shown) based on a predetermined sequence program.

As described above, according to the solenoid valve 1 of this embodiment, as shown in FIG. 1, under the second mode in which the manual valve 5 is located at the non-operating position, the second pressurization is performed. The supply of the pilot pressure to the chamber 12 is allowed, and the outer peripheral groove 23 and the third pressurizing chamber 22 communicate with the atmosphere. For this reason, when the pilot pressure is supplied to the second pressurizing chamber 12 depending on the control of the second pilot valve 45, a thrust is generated in the second piston 19, and as shown in FIGS. The piston 19 presses the spool valve 4 via the third piston 29.
Here, the size of the pressure receiving surface 19a of the second piston 19 and the size of the pressure receiving surface 18a of the first piston 18 are equal to each other. Therefore, the thrust of the first piston 18 pressing the spool valve 4 and the thrust of the second piston 19 pressing the spool valve 4 via the third piston 29 are equal to each other.

Here, the first and second pilot valves 4
4 and 45 are selectively turned on, and the pilot pressure is selectively supplied to the first or second pressurizing chambers 11 and 12. Then, the first or second piston 18, 19 is connected to the spool valve 4.
And the spool valve 4 is selectively moved forward or backward,
The gas flow path in the switching valve unit 2 is switched. At this time, since no pilot pressure is supplied to the third pressurizing chamber 22, the second and third pistons 19 and 29 move integrally while contacting each other as shown in FIGS.

The first and second pilot valves 44 and 45 are both turned off, and the first and second pressurizing chambers 11 and
Both the supply of pilot pressure to 12 is shut off.
Then, the first and second pistons 18 and 19 no longer press the spool valve 4, and the spool valve 4 is held at the position at that time. That is, a self-holding type operation is obtained by the solenoid valve 1.

On the other hand, the first and second pilot valves 44,
45 is simultaneously turned on accidentally and the first and second pressurizing chambers 1
The pilot pressures are supplied to 1 and 12 simultaneously. Then
The first and second pistons 18, 19 press the spool valve 4 by the same thrusts in opposite directions, and the spool valve 4 is held at the current position. Therefore, even if the first and second pilot valves 44 and 45 are erroneously turned on at the same time and pilot pressure is supplied to both pistons 18 and 19 at the same time,
The spool valve 4 does not erroneously move in an unspecified direction, and the fluid flow path in the switching valve unit 2 is not erroneously switched.

In this embodiment, as shown in FIG. 4, when the second piston 19 comes into contact with the bottom surface 10a of the second bore 10 as shown in FIG.
7 rides on the step 31 and is compressed. At this time, the first
In this state, the pilot pressure is not supplied to the outer peripheral groove 23, so that the sealing effect of the first packing 27 is irrelevant here.

Similarly, in the second embodiment, as shown in FIG. 5, the second piston 19 is connected to the bottom surface 1 of the second bore 10.
0a, the first packing 27
Is released from the step 31 and the compression of the packing 27 is released. Therefore, shortly after the second piston 19 starts to move from the position shown in FIG. 4, the first packing 27 is in a state without compression, and the sliding resistance between the first packing 27 and the second bore 10 is reduced. Is reduced. In contrast, the second
The packing 28 exhibits an effective sealing effect to suppress leakage of pilot pressure from the second pressurizing chamber 12,
This causes some sliding resistance to the movement of the piston 19. That is, the second piston 19 has two packings 27 and 28 on its outer periphery,
The source of the sliding resistance at the time of movement of 9 is suppressed only to the second packing 28. In this sense, the movement of the second piston 19 becomes smooth, the responsiveness of the movement of the spool valve 4 increases, and the smooth operation of the solenoid valve 1 is ensured.

On the other hand, as shown in FIG. 6, under the first mode in which the manual valve 5 is operated to be placed in the operating position, the supply of the pilot pressure to the second pressurizing chamber 12 is cut off. Then, the second pressurizing chamber 12 is communicated with the atmosphere. At the same time, the pilot pressure is constantly forcibly supplied to the outer peripheral groove 23 and the third pressurizing chamber 22.

At this time, both inner walls 25 and 26 of the outer circumferential groove 23
, Thrusts in opposite directions are generated by the pilot pressure supplied to the outer peripheral groove 23. Second inner wall 26
Has a larger pressure receiving area than the first inner wall 25, the thrust at the second inner wall 26 exceeds that of the first inner wall 25.
Therefore, as shown in FIGS. 7 and 8, the second piston 19 moves in a direction away from the spool valve 4 based on the difference between the two thrusts, and the piston 19 eventually moves to the bottom surface of the second bore 10. Stop in a state of contact with 10a.

Here, while the pilot pressure is supplied to the outer peripheral groove 23, the above-described thrust difference is generated between the inner walls 25 and 26, and the second piston 19 is moved to the bottom surface 10a based on the thrust. Pressed down and held in that state.
At this time, since the first packing 27 is compressed in contact with the step portion 31, the sealing effect of the packing 27 is obtained. Therefore, leakage of the pilot pressure from the outer peripheral groove 23 is suppressed, and the inner walls 25 and 26 and the third pressure chamber 22 are prevented from leaking.
, The pilot pressure acts effectively. Therefore, malfunction of the second piston 19 is suppressed, and a sufficient thrust is generated in the third piston 29.

In this case, the thrust generated by the third piston 29 pushes the spool valve 4. Here, the pressure receiving surface 18 a of the first piston 18 is larger than the pressure receiving surface 29 a of the third piston 29. For this reason, the thrust of the first piston 18 pressing the spool valve 4 is always greater than the thrust of the third piston 29 pressing the spool valve 4.

Therefore, when the first pilot valve 44 is turned on and the pilot pressure is supplied to the first pressurizing chamber 11, the first piston 18 presses the spool valve 4. At this time, the spool valve 4 is pressed based on the difference between the thrust of the first piston 18 and the thrust of the third piston 29, and moves upward from the state shown in FIG. The flow path is switched.

When the first pilot valve 44 is turned off,
When the supply of the pilot pressure to the pressurizing chamber 11 is stopped and released to the atmosphere, the first piston 18
Is not pressed, and the spool valve 4 becomes the third piston 29
Only by pressing. For this reason, the spool valve 4 moves backward in the direction opposite to the direction based on the thrust difference,
It returns to its end position as shown in FIG. That is, a self-recovery type movement is obtained by the solenoid valve 1.

Therefore, the first and second pilot valves 4
If pilot valves 4 and 45 are accidentally turned on at the same time, pilot valve 4
5 is a flow path configuration not involved in the operation of the pistons 19 and 29, so that the spool valve 4 does not stop in a predetermined direction (the direction in which the third piston 29 comes into contact with the second piston 19).
Therefore, the flow path in the switching valve unit 2 is not erroneously switched. Also, from that state,
Even if the first pilot valve 44 is turned off by mistake, the spool valve 4 does not stop at an unspecified position, and the first pilot valve 44 normally operates.
As in the case where the pilot valve 44 is turned off, it always returns to its end position (the position shown in FIG. 8).
Also, when only the second pilot valve 45 is turned on by mistake, the spool valve 4 does not move at all and is kept at the return position of the origin.

As described above, in this embodiment, in the double solenoid type pilot solenoid valve 1 which is both a self-holding type and a self-returning type, the solenoid valve can be operated simply by switching the manual valve 5. 1 can be easily changed between the self-holding type and the self-resetting type.
Moreover, when the supply of the pilot pressure is set in the first mode, the second piston 19 is securely held at a predetermined position without using a special locking member. In this sense, the setting model can be easily changed.

In this embodiment, the two pilot valves 44 and 45 are erroneously turned on at the same time under the setting of the self-holding type or the self-return type, and the pilot pressure is erroneously supplied to both ends of the spool valve 4 at the same time. Also, the solenoid valve 1 does not cause an unspecified malfunction. That is, even if the pilot valves 44 and 45 are simultaneously turned on under the self-holding type setting and the pilot pressure is supplied to both ends of the spool valve 4, the spool valve 4 does not move in an unspecified direction. It is held in the position when. On the other hand, under the setting of the self-recovery type, the operation of the pilot valve 45 does not affect the operation of the spool valve 4 even if the pilot valves 44 and 45 are simultaneously turned on and the pilot pressure is simultaneously supplied to both ends of the spool valve 4. The spool valve 4 does not stop or move backward, but moves forward in accordance with the movement of the pilot valve 44. In this sense, occurrence of unspecified malfunction of the solenoid valve 1 can be prevented.

In the solenoid valve 1 of this embodiment, when the self-holding type is set, one of the two packings 27, 28 provided on the second piston 19 is used.
Is reduced in sliding resistance. Therefore, the piston 19
The movement of the spool valve 4 and therefore the movement of the spool valve 4 do not receive unnecessarily resistance. Furthermore, under the self-resetting type setting,
The second piston 19 is securely held in place and only one packing 30 provides resistance during the movement of the third piston 29. For this reason, in the solenoid valve 1, good responsiveness can be ensured for each operation under the setting of each model, while ensuring appropriate operation modes for the self-holding type and the self-returning type.

It should be noted that the present invention is not limited to the above-described embodiment, but can be carried out as follows without departing from the spirit of the invention.

(1) In the above embodiment, the actuator unit 3 including the two pilot valves 44 and 45 in the solenoid valve 1 is arranged on one side of the switching valve unit 2. In contrast,
In the solenoid valve, two pilot valves constituting the actuator section may be separately arranged on both sides of the switching valve section.

(2) In the above-described embodiment, the manual valve 5 constituting the switching means is formed in a long axis, and the manual valve 5 is moved up and down, so that the second and third pressurizing chambers 12 and 22
It is configured to switch the supply of the pilot pressure to the same. On the other hand, the manual valve is used as a knob or a lever, and the knobs and the lever are rotated, so that the second and third valves are turned.
The supply of the pilot pressure to the pressurizing chamber or the like may be switched.

[0063]

According to the first aspect of the present invention, the pressure receiving surfaces of the first and second pistons provided in the first and second pressurizing chambers corresponding to both ends of the spool valve. Are made equal to each other, and the pressure receiving surface of the third piston provided in the third pressurizing chamber inside the second piston is made smaller than that of the second piston. In the second piston,
The first inner wall of the outer peripheral groove communicating with the third pressure chamber is made closer to the spool valve than the second inner wall, and the pressure receiving area of the second inner wall is made larger than that of the first inner wall. A first mode in which the second pressure chamber is communicated with the atmosphere and a pilot pressure is constantly supplied to the outer circumferential groove and the third pressure chamber in order to press the spool valve with the third piston; Valve second
In order to press by the piston, the supply of the pilot pressure to the second pressurizing chamber is permitted, and the outer peripheral groove and the second mode in which the third pressurizing chamber is communicated with the atmosphere are switched by switching means. I have.

Therefore, only by switching the supply mode of the pilot pressure between the first and second modes by the switching means,
A self-return type or a self-holding type is selected. And the first
In the aspect, since the spool valve moves forward due to the difference in thrust between the first and third pistons, even if the pilot pressure is simultaneously supplied to the first and third pistons due to the malfunction of the pilot valve, the self-return type There is no erroneous switching of the flow path such that the setting operates like a self-holding type. In the second aspect, since the thrusts of the first and second pistons are balanced with each other, even if pilot pressure is supplied to the first and second pistons simultaneously due to malfunction of the pilot valve, the position of the spool valve is maintained. Therefore, there is no erroneous switching of the flow path, which is supposed to be a self-holding type setting but operates like a self-return type. Therefore, the setting can be easily changed between the self-holding type and the self-returning type, and even if pilot pressure is erroneously supplied to both ends of the spool valve simultaneously at the setting of each model, the solenoid valve is not changed. This has the effect of preventing a specific malfunction from occurring.

According to the second aspect of the present invention, in the first aspect of the present invention, a packing is provided near the first inner wall in the second piston. A step is provided in a part of the bore. Then, when the second piston approaches the bottom surface of the bore, the packing is compressed at the step portion, and when the second piston separates from the bottom surface of the bore, the packing is released.

Therefore, in addition to the function and effect of the first aspect, when the packing is compressed at the stepped portion, a sealing effect is obtained by the packing, and leakage of pilot pressure from the outer circumferential groove is suppressed, and Malfunction of the second piston is suppressed. When the compression of the packing is released, the sliding resistance of the packing is reduced, the movement of the second piston is smooth, and the responsiveness of the movement of the spool valve is enhanced. For this reason, it is possible to ensure the appropriate operation mode of the self-holding type and the self-returning type, and to ensure the good responsiveness of the operation of the solenoid valve under the setting of each model. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of a solenoid valve according to an embodiment of a pilot-type solenoid valve of the present invention.

FIG. 2 is a cross-sectional view showing an enlarged portion of a manual valve.

FIG. 3 is an enlarged sectional view showing a main part of an electromagnetic valve including a spool valve.

FIG. 4 is an enlarged sectional view showing a part of the second and third pistons.

FIG. 5 is an enlarged sectional view showing a part of the second and third pistons.

FIG. 6 is a sectional view showing a portion of the manual valve.

FIG. 7 is an enlarged sectional view showing a part of the second and third pistons.

FIG. 8 is an enlarged cross-sectional view showing a main part of an electromagnetic valve including a spool valve.

FIG. 9 is a sectional view showing the structure of a conventional pilot type solenoid valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solenoid valve 2 Switching valve part 3 Actuator part 4 Spool valve 5 Manual valve 10 Second bore 10a Bottom surface 11 First pressurizing chamber 12 Second pressurizing chamber 18 First piston 18a Pressure receiving surface 19 Second piston 19a Pressure receiving surface 22 Third pressurizing chamber 23 Outer peripheral groove 25 First inner wall 26 Second inner wall 27 First packing 28 Second packing 29 Third piston 30 Third packing 31 Step 36 Pilot air supply Passage 37 Valve hole 40 Second chamber passage 41 Third chamber passage 42 Atmospheric passage 43 Supply / exhaust passage 44 First pilot valve 45 Second pilot valve

Claims (2)

[Claims] 1. A spool valve for switching a flow path of a fluid, and supplied to a first pressurizing chamber and a second pressurizing chamber provided at both ends thereof for driving the spool valve. A pilot valve for controlling a pilot pressure, wherein the spool valve has a first piston corresponding to the first pressurizing chamber and a second piston corresponding to the second pressurizing chamber. The first and second pistons have pressure receiving surfaces of the same size as each other, and the second piston has a third piston in a third pressurizing chamber therein. The pressure receiving surface of the third piston is smaller than the pressure receiving surface of the second piston, and the second piston has an outer peripheral groove communicating with the third pressure chamber. , The outer circumferential groove is in the moving direction of the second piston. A first inner wall and a second inner wall opposed to each other, wherein the second inner wall is disposed closer to the spool valve than the first inner wall, and has a larger pressure receiving area than the first inner wall. In order to press one end of the spool valve with the third piston, the second pressurizing chamber is communicated with the atmosphere, and the pilot pressure is applied to the third pressurizing chamber via the outer peripheral groove. In the first aspect, which always supplies, the pilot pressure is supplied to the second pressurizing chamber in order to press one end of the spool valve by the second piston, and the outer peripheral groove and the second 3. A pilot-type solenoid valve, comprising: switching means for switching the supply mode of the pilot pressure between a third mode in which the pressurizing chamber of No. 3 communicates with the atmosphere. 2. The pilot solenoid valve according to claim 1, wherein the solenoid valve includes a bore for slidably receiving the second piston, and the second piston is provided on an outer periphery of the first piston.
A seal disposed between the outer peripheral groove and the outside thereof, and the bore has a step portion having a smaller diameter than other portions, and the second seal is provided near the inner wall of the second seal.
When the piston comes close to the bottom of the bore, the packing rides on the step and is compressed, and when the second piston moves away from the bottom of the bore, the packing separates from the step. Wherein the compression is released.