JP2798664B2 - 2-position directional control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-position directional control valve used for supplying and exhausting a driving fluid to and from a fluid pressure driven pump, and more particularly to an improvement in a neutral position preventing mechanism for a two-position directional control valve. is there.

[0002]

2. Description of the Related Art Bellows pumps, which are one type of fluid pressure driven pumps, have a relatively stable performance with a light and simple mechanism among reciprocating pumps, as is known, for example, from US Pat. No. 4,920,206. And that the bellows, which is a liquid contact part, can be made of a heat-resistant or corrosion-resistant plastic for a chemical solution.
It is used for a wide range of applications from semiconductor to biotechnology.

As shown in FIG. 4 to which the present invention is applied, a pump mechanism of a bellows pump has a pair of cylinder cases 1 and 2.
2, bellows 3 and 4 provided in cylinder cases 1 and 2 and expanded and contracted by driving fluid pressure, and bellows 3 and 4
A rod 5 having opposite ends connected to opposite end surfaces thereof, and a two-position directional switching valve 6 for alternately sending a driving fluid into the cylinder cases 1 and 2 are provided. A switching lever 12, which is a pilot valve actuating member that reciprocates in conjunction with a reciprocating pump, is attached to the rod 5, and the switching lever 12 operates the pilot valves 11A and 11B alternately to operate the pilot valve. Pilot fluid is applied to the position directional control valve to switch the two position directional control valve. This allows
The two-position directional control valve 6 alternately supplies bellows 3 and 4 by alternately supplying the driving fluid pressure-fed via the three-way valve 7A into the cylinder cases 1 and 2 and exhausting the other from the other cylinder case. To expand and contract, bellows 3, 4
It is possible to repeatedly perform suction and discharge of the liquid from the liquid ports 8, 9 provided in the apparatus.

FIG. 5 shows a conventional example of the two-position directional control valve. The two-position directional control valve 60 includes a valve box 61 forming a plurality of ports, a spool 62 disposed in the valve box 61, and drive chambers 6 provided on both sides of the spool 62.
0a and 60b, and the driving chamber 63a is supplied with the fluid pressure of the pilot fluid supplied / exhausted to / from the driving chambers 60a and 60b via pilot valves (reference numerals 11A and 11B in FIG. 4).
a and 63b to cause the spool 62 to reciprocate,
The communication between the ports is switched. The ports include an input port P1 for introducing a drive fluid, output ports P2 and P3 for introducing the drive fluid from the input port P1 to the cylinder cases 1 and 2, and an output port for the drive fluid in the cylinder cases 1 and 2. It comprises discharge ports P4 and P5 which receive and discharge from ports P2 and P3.

FIG. 5A shows a state where the pilot fluid is supplied to the driving chamber 60b. At this time, the input port P1 communicates with the output port P3, and the output port P2 communicates with the discharge port P4. In relation to the bellows pump, the drive fluid is pumped to one side of the cylinder cases 1 and 2,
The drive fluid is exhausted from the other side. Conversely, FIG. 5B shows a state in which the pilot fluid is supplied to the driving chamber 60a. At this time, the input port P1 communicates with the output port P2, and the output port P3 communicates with the discharge port P5. In relation to the bellows pump, the driving fluid is pumped to the other side of the cylinder cases 1 and 2, and the driving fluid is exhausted from one side. As described above, the two-position directional control valve 60 includes the drive chamber 60
Pilot fluid alternately sent between a and 60b, that is, a pulse-like switching pressure, moves between the two switching positions to regularly switch the communication between the ports.

[0006]

In the two-position directional control valve 60 described above, when the drive and the supply of the pilot fluid are stopped to stop the bellows pump, the spool 6
2 also stops in conjunction with it. At that time, finally, the pilot fluid pressure acting on the drive chamber is insufficient, and as shown in FIG. 6C, the input port P1 is stopped at a neutral position where the input port P1 does not communicate with any of the output ports P2 and P3. Also wakes up. In this state, since the input port P1 is not in communication with any of the output ports P2 and P3, the driving fluid is
When the bellows pump is started again,
It cannot be driven. As a countermeasure against this,
For example, a bypass circuit for connecting the pilot fluid source to one of the drive chambers is provided, and the spool 62 is moved from the neutral position to one of the switching positions by operating a manual valve on the bypass circuit. In this structure,
Since it is necessary to check and operate the manual valve as necessary every time the system is restarted, there has been a problem that not only the reduction of the operation rate but also the automation of the pump drive is not sufficiently achieved.

Further, the prior art includes, for example,
As described in Japanese Patent No. 26385, there is also known a neutralization preventing mechanism in which a spring member is disposed in one driving chamber. This neutral prevention mechanism has the following problems. That is, the spring member contracts and expands against the spring pressure each time the spool reciprocates by the bi-rot fluid, so that the spring pressure gradually decreases, the spring life is short, and the spring member must be replaced frequently. . Such maintenance work lowers the operating rate and is uneconomical. In addition, since the spool must move against the urging force of the spring member, the switching operation of the switching valve may become unstable due to fluctuations in the pilot fluid pressure. If it is expected, it cannot be adopted at all.

The present invention solves the above problems. A first object of the present invention is to improve the operation rate and reliability by structurally eliminating the neutral position of the spool described above. A second object is to use the spring member and a part of the pilot fluid as the neutralization preventing mechanism so that the spring life of the used spring member can be maintained for a long time.

[0009]

In order to achieve the above object, a two-position directional control valve according to the present invention has a plurality of ports P1 to P5 as illustrated in FIGS. A box 18, a spool 19 disposed in the valve box 18, and drive chambers 20 a and 21 a provided on both sides of the spool 19, and the drive chamber 2 is provided via pilot valves 11 A and 11 B.
A two-position directional control valve 6 for switching the communication between the ports by moving the spool 19 between two switching positions by the fluid pressure of the pilot fluid supplied to and exhausted from the ports 0a and 20b.
, An auxiliary piston chamber 27 provided on one side of the drive chambers 20a and 21a via a wall, and an auxiliary piston chamber 27
Auxiliary piston member 28 which is disposed in the drive chamber 20a or 21a and which can be
And a spring member 29 for urging the auxiliary piston 28 into a direction protruding into the drive chamber 20a or 21a, and an auxiliary fluid introduced into the auxiliary piston chamber 27 so that the auxiliary piston 28 can be moved away from the drive chamber by the auxiliary fluid pressure. Auxiliary fluid passage 3
0, and when the auxiliary fluid is not applied to the auxiliary piston chamber 27 from the auxiliary fluid passage 30, the auxiliary piston member 28 projects into the drive chamber by the urging force of the spring member 29 to press the spool 19. When the auxiliary fluid is being applied from the auxiliary fluid passage 30 to the auxiliary piston chamber 27, the auxiliary fluid pressure does not prevent the auxiliary piston member 28 from moving between the two switching positions of the spool 19 against the spring member 29. It is provided with a neutral prevention mechanism 26 for retracting to a position.

In the configuration of the present invention described above, the neutralization preventing mechanism 26 is integrally mounted on one side of the cover members 20 and 21 mounted on both sides of the valve box 18 to form the drive chamber 20a or 21a. Is preferred. However, the present invention is not limited to this, and the neutralization preventing mechanism 26 may be a separate neutral member 3 forming the auxiliary fluid passage 30 and the auxiliary piston chamber 27.
6, the auxiliary piston member 28 and the spring member 29 are incorporated, and the driving chamber 20a
Alternatively, the neutral member 36 may be attached to one side of the cover members 20 and 21 forming the 21a.
Further, as the spring member 29, a compression coil spring, a leaf spring, or the like is used. In this case, the compression coil spring is more excellent in selection and stability of the spring pressure. Further, in the above configuration of the present invention, it is preferable to use a part of the pilot fluid as the auxiliary fluid. That is, the pilot fluid is supplied and exhausted from the pilot fluid source to the drive chambers 20a and 21a through the three-way valve 7B and the pair of pilot valves 11A and 11B, and the three-way valve 7B and the pilot valves 11A and 11A. Pipe 17d that connects between 11B
(By-pass piping) is introduced into the auxiliary piston chamber 27.

The two-position directional control valve of the present invention is used for supplying / exhausting a driving fluid to a fluid pressure driven pump (a bellows pump illustrated in FIG. 4), and includes a pilot valve 11A,
11B is used as a form in which the pilot fluid is supplied by operating via a pilot valve operating member (a switching lever 12 in the bellows pump illustrated in FIG. 4) interlocked with the hydraulic drive pump. As the fluid pressure driven pump, in addition to the bellows pump illustrated in FIG. 4, a diaphragm pump having a bellows portion of the bellows pump as a diaphragm or the like can be given. Further, when the two-position directional control valve having the above configuration is applied to the fluid pressure driven pump, if the drive and the application of the pilot fluid source are stopped to stop the pump, the pilot fluid is not supplied to the auxiliary piston chamber. For this reason, the auxiliary piston member protrudes by the urging force of the spring member and pushes the spool to the one-way switching position. On the other hand, while the pilot fluid pressure is being applied, the pilot fluid is also supplied from the auxiliary fluid passage to the auxiliary piston chamber, and the auxiliary piston member is supplied with the pilot fluid pressure supplied to the auxiliary piston chamber. Accordingly, the state of being retracted from the drive chamber against the urging force of the spring member is maintained, and the movement of the spool between the two switching positions is not hindered.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the description of the embodiment, various technically preferable limitations are added because they are preferable examples of the invention. However, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 shows a two-position directional control valve for a bellows pump which is an essential part of the present invention, FIG. 2 shows the two-position directional control valve in a different mode, and FIG. 3 shows a modification of the two-position directional control valve. For example, FIG. 4 shows a drive system for a bellows pump using the two-position directional control valve. As described above, the bellows pump includes a pair of cylinder cases 1 and 2 and plastic bellows 3 provided in the cylinder cases 1 and 2 and expanded and contracted by driving fluid pressure.
4, a rod 5 having both ends connected to opposite end surfaces of the bellows 3 and 4 and a two-position direction switching valve 6 for alternately sending a driving fluid into the cylinder cases 1 and 2. The two-position directional control valve 6 alternately supplies and drives the pressure-fed driving fluid into the cylinder cases 1 and 2 and exhausts the other from the other cylinder case, thereby causing the bellows 3 and 4 to expand and contract alternately. This makes it possible to repeatedly suction and discharge the liquid from the liquid ports 8, 9 provided in the bellows 3, 4.

Here, first, the configuration related to the bellows pump mechanism will be outlined. The cylinder cases 1 and 2
The housing 13 is installed horizontally at a predetermined distance from the housing 13. The bellows 3 and 4 are housed in the cylinder cases 1 and 2 so as to be able to expand and contract left and right by fixing one end face. Liquid inlets and outlets 8 and 9 are provided on the fixed side end surfaces of the bellows 3 and 4. The bellows 3 and 4 are connected to the pump case 1 via the liquid ports 8 and 9.
It communicates with a liquid feed pipe 14 with a check valve 10 on the fifth side. The rod 5 connects the bellows 3, 4 with each other, and is moved right and left following the expansion and contraction of each bellows. A switching lever 12 which is a pilot valve operating member is connected to the rod 5. The switching lever 12 is moved left and right following the movement of the rod 5 to alternately push contact points of pilot valves 11A and 11B, which will be described later, and actuate the pilot valves 11A and 11B to perform pilot switching. Pressure is generated to switch the two-position directional control valve.

Next, the configuration related to the two-position directional control valve will be outlined. The two-position directional control valve 6 includes bellows 3,
A pipe for flowing a driving fluid (for example, a compressed gas of 4 kg / cm ² ) that expands and contracts 4 is connected to a pipe for flowing a pilot fluid (for example, a compressed gas of ² kg / cm ² ) that operates the switching valve itself. . In FIG. 4, a solid line indicates a pipe for flowing the driving fluid, and a broken line indicates a pipe for flowing the pilot fluid.
Among these, the pipe for the driving fluid is a pipe 16a that leads from the driving fluid source to the two-position directional control valve 6 (input port P1) via the three-way valve 7A, and the two-position directional control valve 6 (output ports P2 and P3). And pipes 16b and 16c connecting the cylinder cases 1 and 2 with each other. Symbols 16d, 16e
Are cylinder cases 1 and 2 in the process of reducing bellows 3 and 4.
The drive fluid in the chamber is supplied to the two-position directional control valve 6 (exhaust port P4,
This is a pipe for exhausting from P5). On the other hand, the piping for the pilot fluid includes a piping 17a that leads from the pilot fluid source to the pilot valves 11A and 11B via the three-way valve 7B, and the pilot valves 11A and 11B and the two-position direction switching valve 6 (the driving chamber 20a to be described later). And 21a), and pipe 1 connecting pipe 17a and two-position directional control valve 6 (auxiliary fluid passage 30 described later).
7d.

FIGS. 1 and 2 show the structure of the main part of the two-position directional control valve 6. FIG. The two-position directional control valve 6 includes a valve box 18 forming a plurality of ports, a spool 19 disposed on the valve box 18, a cover member 20 attached to both sides of the valve box 18 with screws or the like. 21 and each of the cover members 20 and 2
1, a driving chamber 20a in which the driving piston 22 is disposed and a driving chamber 21a in which the driving piston 23 is disposed. The driving chambers 20a and 21a are supplied via pilot valves 11A and 11B. The drive pistons 22 and 23 operate by the fluid pressure of the pilot fluid to be exhausted to move the spool 19 between the two switching positions and switch the communication between the ports. Reference numeral 25a denotes a packing mounted on both sides of the spool 19. Sign 2
5b is a packing mounted on the drive pistons 22 and 23.

Here, the cover members 20, 21 are provided with passages 24a, 24b communicating with the drive chambers 20a, 21a. In each of the passages 24a and 24b, the aforementioned pipe 1
7b and 17bc are connected. Further, the port is an input port P1 provided at an intermediate portion for introducing a driving fluid.
Output ports P2, P3 provided on both sides of the input port P1 for introducing the driving fluid from the input port P1 into the cylinder cases 1, 2, and provided on both sides of the output ports P2, P3. Discharge ports P4, P5 which receive and discharge the drive fluid in the second 2 from the output ports P2, P3.
Consists of The input port P1 is connected to the pipe 16a. Output ports P2 and P3 are connected to pipes 16b and 16c. The discharge ports P4 and P5 are connected to pipes 16d and 16e.

The two-position directional control valve 6 has a neutral preventing mechanism 26 incorporated in the cover member 20. The neutral prevention mechanism 26 includes an auxiliary piston chamber 27 provided between the drive chamber 20a and the drive chamber 20a, an auxiliary piston member 28 disposed in the auxiliary piston chamber 27 and capable of moving in and out of the drive chamber 20a, The member 28 is connected to the drive room 20
The auxiliary fluid passage 30 includes a spring member 29 for urging in a direction protruding to the direction a, and an auxiliary fluid passage 30 for introducing a part of the pilot fluid into the auxiliary piston chamber 27.

The auxiliary piston chamber 27 is provided with a concave portion 27a on the outer portion of the cover member 20, and the concave portion 27a
Is closed by a lid 31. A through hole 32 is provided in a wall portion between the auxiliary piston chamber 27 and the drive chamber 20a. The auxiliary piston member 28 has a large diameter head 28a and a small diameter shaft 28b. Head 28
A peripheral groove is provided in the outer peripheral portion of a, and a packing 33 is mounted in the peripheral groove. In this packing 33, the pilot fluid that is pressure-fed to the auxiliary piston chamber 27 via the auxiliary fluid passage 30 does not leak to the spring member 29 side of the auxiliary piston chamber 27 from the gap between the head portion 28a and the inner peripheral surface of the concave portion 27a. To do. Similarly, a circumferential groove is provided in a substantially intermediate portion of the shaft portion 28b, and the packing 34 is provided in the circumferential groove.
Is installed. This packing 34
a and the space between the auxiliary piston chamber 27 and the auxiliary piston chamber 27 are kept airtight. The lid 31 has a small through hole. Spring member 29
Uses a compression coil spring, and is positioned and arranged in a concave portion provided on the end face of the head 28a. This spring member 29 may be a leaf spring or the like. Is preferred.

In each of the above members, first, the auxiliary piston member 28 is incorporated in the auxiliary piston chamber 27. in this case,
The auxiliary piston member 28 has a head portion 28a having a concave portion 27a.
And the shaft portion 28b is provided in the through hole 3
2 so as to be movable. The auxiliary piston member 28
In this assembled state, it is located substantially coaxially with the spool 19. Next, after disposing the spring member 29 in the concave portion of the head 28, the lid 31 is fixed to the end surface of the cover member 20 with a plurality of screws 35. Then, the auxiliary piston member 28
In the state in which the spring member 29 is incorporated, the spring 19 protrudes into the drive chamber 20a by the urging force of the spring member 29, and the protrusion pushes the drive piston 22 to move the spool 19 to one switching position. That is, in the assembled state, the spool 19 is operated by the spring member 29 or is in a drive standby state.

The neutralization preventing mechanism 26 is incorporated in the drive system of the bellows pump by connecting the above-described pipe 17d to the auxiliary fluid passage 30. Hereinafter, the operation of the main part of the drive system incorporating the neutralization preventing mechanism 26 will be described. When the bellows pump is operating, that is, when the driving fluid pressure and the pilot fluid pressure are applied, the pilot fluid is supplied to the pipes 17b and 17 as shown in FIG.
The pressure is alternately fed to the passages 24a and 24b through the line c, and is applied from the auxiliary fluid passage 30 to the auxiliary piston chamber 27 through the pipe 17d. As described above, when the pilot fluid is being applied to the auxiliary piston chamber 27, the auxiliary piston member 28 is moved by the fluid pressure against the urging force of the spring member 29 and retracted from the drive chamber 20a. This retracted state is maintained until the application of the pilot fluid pressure is stopped, that is, the bellows pump is stopped.

The operation of the bellows pump itself is performed in the same manner as in the prior art. That is, FIG. 2A shows the driving room 21a.
3 shows a state where the pilot fluid is supplied from the passage 24b. At this time, the input port P1 and the output port P3
And the output port P2 communicates with the discharge port P4.
In relation to the bellows pump, the driving fluid is pumped (discharged from the corresponding bellows) to one side of the cylinder cases 1 and 2, and the driving fluid is exhausted (sucked into the corresponding bellows) from the other side. When the switching lever 12 hits and pushes the pilot valve 11A or the pilot valve 11B, the pilot fluid is supplied to the drive chamber 20a. In this case, as shown in FIG. 2B, the input port P1 communicates with the output port P2, and the output port P3 communicates with the discharge port P.
5 communicates. In relation to the bellows pump, the pumping and exhausting of the drive fluid to the cylinder cases 1 and 2 is the reverse of the above. Thus, the two-position directional control valve 6 is connected to the drive chamber 20.
The communication between the ports is regularly switched by a pilot fluid, that is, a pulse-like switching pressure alternately sent to a and 21a.

FIG. 3 shows a modification of the present invention in a state similar to FIG. This modification is different from the above-described neutral prevention mechanism 2.
6 in that a dedicated neutral member 36 is used. That is, the neutral member 36 forms the above-described auxiliary fluid passage 30, the auxiliary piston chamber 27, and the through hole 34. An auxiliary piston member 28 and a spring member 29 are incorporated in the auxiliary piston chamber 27. Thereafter, the lid 31 is attached. In this case, the neutral member 36
Is integrated with the cover member 21 at the same time when the lid 31 is attached. In this configuration, the cover member 21 forming the drive chamber 21a has a through hole 32 that communicates with the through hole 32.
a is provided. Other configurations are the same as those in FIG.

As described above, the neutral prevention mechanism 26 of the present invention is used.
When the pilot fluid source is applied, as described above, the auxiliary piston member 28 projects into the drive chamber 20a by the urging force of the spring member 29, and the projection pushes the drive piston 22 to move the spool 19 toward the drive chamber 21a. And the spool 19 is operated or put into a drive standby state. Thus, according to the present invention, the manual valve (reset valve) as in the related art can be eliminated, and the operation rate can be improved. Further, since the spring member 29 does not expand and contract during operation of the bellows pump unlike the related art, the initial spring pressure can be maintained for a long time, and the life is prolonged.

[0025]

As described above, when the two-position directional control valve of the present invention is used as a driving fluid directional switching valve of a fluid pressure driven pump, it is necessary to shut off the driving fluid source and the pilot fluid source to stop the pump. Since the pilot fluid is not supplied to the auxiliary piston chamber, the auxiliary piston member is protruded by the urging force of the spring member to push the spool and set the spool to one of the switching positions. That is, the pump can be restarted. On the other hand, while the pilot fluid pressure is being applied, the pilot fluid is also supplied from the auxiliary fluid passage to the auxiliary piston chamber, and the auxiliary piston member is spring-loaded by the pilot fluid pressure supplied to the auxiliary piston chamber. It is maintained in a state of being retracted from the drive chamber against the urging force of the member. Therefore, during the operation of the pump, the spring member is kept in a compressed state, so that the spring member does not expand or contract against the spring pressure in conjunction with the movement of the spool as in the related art. In addition, the spring pressure is hardly attenuated, and the life of the incorporated spring member can be maintained for a long time. Further, during operation, since the spring pressure of the spring member is not applied to the spool, the movement between the two positions is performed normally even if the pilot fluid pressure slightly fluctuates. As a result, the maintenance rate can be reduced, the operation rate can be improved, and the reliability can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part showing a two-position directional control valve for a bellows pump to which the present invention is applied.

FIG. 2 is a sectional view of a main part showing the two-position directional control valve of FIG. 1 in a different mode.

FIG. 3 is a cross-sectional view of a main part showing a modified example of the above-described two-position directional control valve for a bellows pump.

FIG. 4 is a drive system diagram of a bellows pump using the two-position directional control valve of FIG. 1;

FIG. 5 is a view for explaining a problem of a conventional two-position switching valve for a bellows pump.

[Explanation of symbols]

 1, 2 cylinder case 3, 4 bellows 5 rod 6 2 position direction switching valve 7A, 7B three-way valve 11A, 11B pilot valve 12 switching lever 18 valve box 19 spool 20, 21 cover member 20a, 21a drive chamber 22, 23 drive piston 26 Neutralization Prevention Mechanism 27 Auxiliary Piston Chamber 28 Auxiliary Piston Member 29 Spring Member 30 Auxiliary Fluid Passage 36 Neutral Member P1, P2, P3, P4, P5 Port

──────────────────────────────────────────────────続 き Continued on the front page (72) Takao Nakazawa, Inventor 1-29-28, Zenpukuji, Suginami-ku, Tokyo (72) Inventor Yatsukatsu Nishikata 1-6-1, Kandajinbocho, Chiyoda-ku, Tokyo Nisso Engineering Co., Ltd. 72) Inventor Takamichi Takamichi 1-6-1, Kanda Jimbocho, Chiyoda-ku, Tokyo Nisso Engineering Co., Ltd. (72) Inventor Tsutomu Kawashima 1-6-1, Kanda Jimbocho, Chiyoda-ku, Tokyo Nisso Engineering Co., Ltd. 56) References: JP 5-26385 (JP, Y2) (58) Fields studied (Int. Cl. ⁶ , DB name) F16K 31/122 F16K 11/07

Claims (4)

(57) [Claims] 1. A valve box having a plurality of ports, a spool disposed in the valve box and movable between two switching positions, and drive chambers provided on both sides of the spool. A two-position directional control valve for switching the communication between the ports by moving the spool between two switching positions by a fluid pressure of a pilot fluid supplied to and exhausted from the two driving chambers via a pilot valve. An auxiliary piston chamber provided on one side of the chamber via a wall, an auxiliary piston member disposed in the auxiliary piston chamber and capable of protruding and retracting in the adjacent driving chamber, and projecting the auxiliary piston member into the driving chamber. A spring member that urges the auxiliary piston in the direction, and an auxiliary fluid passage that introduces an auxiliary fluid into the auxiliary piston chamber and moves the auxiliary piston away from the drive chamber by the auxiliary fluid pressure. When the auxiliary fluid is not applied from the auxiliary fluid passage to the auxiliary piston chamber, the auxiliary piston member projects into the drive chamber by the urging force of the spring member to press the spool, When auxiliary fluid is applied from the auxiliary fluid passage to the auxiliary piston chamber, the auxiliary fluid pressure causes the auxiliary piston member to oppose the spring member and not hinder the movement of the spool between the two switching positions. A two-position directional control valve, comprising a neutral preventing mechanism for retracting the directional control valve. 2. The pilot valve is used to supply and exhaust a driving fluid to and from a fluid pressure driven pump, and the pilot valve is operated via a pilot valve operating member interlocked with the fluid pressure driven pump to supply the pilot fluid. The two-position directional control valve according to claim 1. 3. The two-position directional control valve according to claim 2, wherein said fluid pressure driven pump is a bellows pump. 4. The two-position direction switching according to claim 1, wherein a pilot fluid pipe leading to the pilot valve is connected to the auxiliary fluid passage via a bypass pipe, and a part of the pilot fluid is used as the auxiliary fluid. valve.