WO2005064169A1

WO2005064169A1 - Direct solenoid-operated four-way directional control valve

Info

Publication number: WO2005064169A1
Application number: PCT/KR2004/003376
Authority: WO
Inventors: Yun-Boon Lee
Original assignee: Aser Tech Co., Ltd.
Priority date: 2003-12-30
Filing date: 2004-12-21
Publication date: 2005-07-14
Also published as: KR20050068696A

Abstract

Provided is a direct solenoid-operated four-way directional control valve, which can be made compact and mass-produced through synthetic resin injection molding. The four-way directional control valve includes a valve body composed of four body blocks that are sequentially adhered, and first and second valve rooms each formed between adjacent body blocks of the adhered body blocks. A supply port, a load port, and an exhaust port pass through each valve room, and first and second valve mechanisms alternately opening and closing the supply port and the load port are respectively inserted into the first and second valve rooms. The first valve mechanism interlocks with a plunger of a solenoid mechanism, and the second valve mechanism coorindates with a piston member that is moved by a pressure of fluid controlled by the first valve mechanism. Each body block can be made of a synthetic resin material through injection molding, and the valve mechanisms respectively inserted into the first and second valve rooms can be made compact and can be fast converted, differently from those of conventional spool valves.

Description

DIRECT SOLENOID-OPERATED FOUR-WAY DIRECTIONAL CONTROL VALVE

Technical Field The present invention relates to a direct solenoid-operated four-way directional control valve, and more particularly, to a new valve structure, which can be made compact and mass-produced through synthetic resin injection molding.

Background Art Four-way directional control valves, which have four or five ports to divert fluid flow, are used to change the direction of motion of an actuator such as a pneumatic cylinder or a hydraulic cylinder. There are various methods of operating valves. Valves directly operated using an electrical thrust of a solenoid are referred to as direct solenoid-operated valves. As four-way directional control valves, slide spool valves are mainly used. U.S.

Patent No. 4,566,490 discloses a direct solenoid-operated four-way directional control valve in which a slide spool valve is combined with a solenoid mechanism. U.S. Patent No. 6,325,102 discloses a pilot-operated four-way directional control valve in which a pilot valve is combined with a solenoid mechanism using a slide spool valve as a main valve. In general, a slide spool valve has a spool bore through which a valve spool moves in an axial direction. The spool bore is processed with high precision to have an inner cylindrical sliding surface so that valve portions of the valve spool can be maintained airtight. Ports penetrating the inner sliding surface of the spool bore are spaced at predetermined intervals in an axial direction, and a valve room having a great diameter extends from each open port. The valve spool has a flange shape along the inner circumference of the spool bore in accordance with the spacing of the ports. Each of the valve portions of the valve spool is encompassed by an elastic seal member to prevent friction with and seal the inner sliding surface of the spool bore. If a valve portion is disposed between two adjacent ports on the cylindrical sliding surface, the space between the adjacent ports is blocked, and if the valve portion is disposed in the extending valve room, ports in the valve room are opened. That is, the ports are selectively opened and closed depending on the position where the valve spool is operated, thereby controlling the fluid flow. A solenoid is connected to the valve spool in the axial direction, and is designed to have a thrust and stroke considering the friction and travel distance of the valve spool.

Brief Description of the Drawings FIG. 1 is a perspective view of a direct solenoid-operated four-way directional control valve according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a coupling structure among body blocks of a valve body of the direct solenoid-operated four-way directional control valve shown in FIG. 1. FIG. 3 is a side view of a main part illustrating a coupling structure between a solenoid mechanism and the valve body of the direct solenoid-operated four-way directional control valve shown in FIG. 1. FIG. 4A is a longitudinal sectional view illustrating an internal structure of the direct solenoid-operated four-way directional control valve shown in FIG. 1 , which is in a normal state. FIG. 4B is a longitudinal sectional view illustrating the internal structure of the direct solenoid-operated four-way directional control valve shown in FIG. 1 , which is in a converted state. FIG. 5 is a sectional view of the direct solenoid-operated four-way directional control valve taken along line V-V of FIG. 4A. FIG. 6 is a partial cut away perspective view of a valve mechanism used in the direct solenoid-operated four-way directional control valve shown in FIG. 1.

Detailed Description of the Invention Technical Goal of the invention Since a direct solenoid-operated four-way directional control valve is operated using an electrical signal, the valve is easy to use in a remote control, automatic control, emergency stop, and has a fast and accurate response time. However, the valve is not suitable for a case of controlling a huge amount of fluid, and thus it is usually used to control a small actuator. Hence, the direct solenoid-operated four-way directional control valve needs to be made compact. However, a slide spool valve used as a conventional four-way directional control valve has a structural miniaturization limitation in consideration of the friction and stiffness of a valve spool and the thrust and stroke of a solenoid that moves the valve spool. The slide spool valve also has a structural disadvantage in that it is difficult to be formed by synthetic resin injection molding due to the shape of a valve room extending in a spool bore of a body. In addition, since the slide spool valve cannot be formed of iron, which erodes due to moisture or the like, the valve room in the spool bore is processed after aluminum die casting, and accordingly, the manufacture thereof is difficult and the cost is high, remarkably decreasing productivity and increasing manufacturing costs. The present invention provides a direct solenoid-operated four-way directional control valve which can be made compact and mass-produced through synthetic resin injection molding.

The Structure of the Invention In accordance with an aspect of the present invention, there is provided a direct solenoid-operated four-way directional control valve comprising: a valve body including a plurality of ports comprised of one supply port, two load ports, and two exhaust ports through each of which fluid enters and exits, a first valve room through which the supply port, one of the two load ports, and one of the exhaust ports pass, a second valve room through which the supply port, the other one of the two load ports, and the other one of the exhaust ports pass, and a fluid operation room communicating with the first valve room and filled with fluid supplied from the first valve room; a solenoid mechanism coupled to the valve body, driven to produce an electrical thrust using an external electrical signal, and having a plunger moved forward and backward due to the electrical thrust; a first valve mechanism movably accommodated in the first valve room of the valve body and interlocking with the plunger of the solenoid mechanism to alternately open and close the supply port and the exhaust port among the ports passing through the first valve room; a piston member installed in the fluid operation room of the valve body and moved by a pressure of the fluid filled in the fluid operation room; and a second valve mechanism movably accommodated in the second valve room of the valve body and interlocking with the piston member to alternately open and close the supply port and the exhaust port among the ports passing through the second valve room. The supply port is connected one of the two load ports and the other load port is connected to the exhaust port according to the driving of the solenoid mechanism. The valve body may be formed by adhering four body blocks that are separated using the first and second valve rooms and the fluid operation room as borders. The solenoid mechanism may comprise: a solenoid coil excited by an external electrical signal and producing an electrical thrust; a coil bobbin wound with the solenoid coil; the plunger movably inserted into the coil bobbin and pulled by the electrical thrust of the solenoid coil; and a plunger spring elastically restoring the plunger when the electrical thrust of the solenoid coil is removed. The first valve mechanism may comprise: a valve member made of an elastic material and having valve elements formed at both ends thereof to alternately open and close the supply port and the exhaust port passing through the first valve room; a valve holder allowing the valve member to be fitted thereinto, and having an interlocking protrusion that passes through an inner wall of the first valve room and contacts and interlocks with an end of the plunger of the solenoid mechanism; and a valve spring elastically supporting the valve holder and pushing the valve holder in an opposite direction to a pressure of fluid applied to the plunger. The second valve mechanism may comprise: a valve member made of an elastic material and having valve elements formed at both ends thereof to alternately open and close the supply port and the exhaust port passing through the second valve room; a valve holder allowing the valve member to be fitted thereinto and having an interlocking protrusion that passes through an inner wall of the second valve room and contacts and interlocks with the piston member of the fluid operation room; and a valve spring elastically supporting the valve holder and pushing the valve holder in an opposite direction to the pressure of the fluid applied to the piston member. The fluid operation room may have a cylindrical sliding surface, and include a pressure seal member wound around the piston member to maintain sealing with the sliding surface and receiving the pressure of the fluid to be moved together with the piston member.

The Effect of the Invention As described above, since the valve body is formed by adhering a plurality of body blocks that are separated using internal valve rooms as borders, each body block can be manufactured by injecting synthetic resin, thereby reducing the manufacturing cost of the valve. The rate of defective products is reduced because complicated post-processes are omitted, and manufacturing costs of the valve are drastically reduced because the valve can be mass-produced. Furthermore, since the direct solenoid-operated four-way directional control valve uses a seat valve instead of a conventional slide spool valve, the valve body and the solenoid mechanism can be made compact whether or not fluid is huge, and a faster conversion can be made with a shorter stroke.

Best mode for carrying out the Invention The present invention will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. FIG. 1 is a perspective view of a direct solenoid-operated four-way control valve according to an embodiment of the present invention. As shown in FIG. 1 , the direct solenoid-operated four-way directional control valve includes a valve body 10 and a solenoid mechanism 20. The valve body 10 is comprised of four body blocks 10a through 10d that are sequentially adhered to the solenoid mechanism 20, and has bolt fixing parts 11 to be fixed to a manifold block (not shown). It is preferable that the bolt fixing parts 11 having semi-cylindrical shapes be formed at a first edge of a side surface of the first body block 10a and at a second edge of a side surface of the fourth body block 10d located opposite in a diagonal direction to the first edge, and semicircular grooves 12 be formed at corresponding edges opposite to the semi-cylindrical bolt fixing parts 11 to receive the semi-cylindrical bolt fixing parts 11. Accordingly, when the manifold block is installed in a state where a plurality of valve bodies 10 are adjacent to one another, the width of the valve bodies 10 can be minimized and the entire area occupied by the valve bodies 10 can be reduced. Referring to FIG. 2, the body blocks 10a through 10d of the valve body 10 are joined as one body by inserting long bolt members 13 into the body blocks 10a through 10d. To this end, the first body block 10 has a screw groove 14a, and the remaining body blocks 10b through 10d have bolt through-holes 14b through 14d aligned with the screw groove 14a. Seal members 15a through 15c are inserted into interfaces among the body blocks 10a through 10d, which are coupled to one another by the bolt members 30, as shown in FIGS. 4A and 4B to prevent fluid leakage. The valve body 10 and the solenoid mechanism 20 are simply coupled as shown in FIG. 3. The valve body 10 includes a frame fixing part 16 formed at a side surface of the first body block 10a, and the solenoid mechanism 20 includes a frame 27 having a bent catching section 27a by which the frame fixing part 16 is caught not to be separated from the solenoid mechanism 20. Referring to FIGS. 4A and 4B, the valve body 10 has five ports, two formed in the first body block 10a, two formed in the second body block 10b, and one formed in the third body block 10c. The five ports are a supply port P, load ports A and B, and exhaust ports Ra and Rb. The supply port P is connected to an air pump or an accumulator, which is conventional pneumatic pressure generating equipment, to receive compressed air. The load ports A and B are connected to an actuator, such as an air cylinder, to output and collect compressed air. The exhaust ports Ra and Rb outwardly discharge the compressed air collected by the load ports. The valve body 10 includes a solenoid operation room 17 opened at a front surface of the first body block 10a, a first valve room 40a formed between the first and second body blocks 10a ad 10b, a second valve room 40b formed between the second and third body blocks 10b and 10c, and a fluid operation room 60 formed between the first and fourth body blocks 10c and 10d. Since the four body blocks 10a through 10d constituting the valve body 10 are designed to be separated from one another by the first and second valve rooms 40 and 40b and the fluid operation room 60 formed thereinside, each body block can be made of a synthetic resin material through injection molding. A head portion of a plunger 23 of the solenoid mechanism 20 is inserted together with a plunger spring 24 into the solenoid operation room 17 of the first body block 1 1. The solenoid mechanism 20 includes a solenoid coil 21 excited by an external electrical signal and producing an electrical thrust, a coil bobbin 22 wound with the solenoid coil 21 , the plunger 23, the plunger spring 24, a fixed iron core 25, seal members 26, the aforesaid frame 27, a frame housing 28, and an adapter plate 29. Here, the solenoid coil 21 pulls the plunger 23 toward the coil bobbin 22 with an electrical thrust exceeding the plunger spring 24. The plunger spring 24 is contracted due to the electrical thrust of the solenoid coil 21 , and elastically restores the plunger 23 when the electrical thrust is removed. The fixed iron core 25 fixedly inserted into the coil bobbin 22 is spaced from the plunger 23 as apart as a stroke of the plunger 23, and is wound by the seal members 26. The first body block 10a of the valve body 10 also has a button hole 18 extending from a top surface of the first body block 10a to an end of the solenoid operation room 17, and a pin hole 19 extending from the front surface of the first body block 10a to a middle point of the button hole 18. A push button 30 inserted into the button hole 18 is elastically supported by a button spring 35 to be restored after a push operation, and has a slope portion 31 and a stopper groove 32. The slope portion 31 is adjacent to the head portion of the plunger 23 inside the solenoid operation room 17 to push rearward the plunger 23 during the push operation of the push button 30. A stopper pin 33 inserted into the pin hole 18 of the first body block 10a is also inserted into the stopper groove 32 such that the push button 30 can perform its push operation by a predetermined distance but can be prevented from being separated from the button hole 18. A seal member 34 wound around the push button 30 prevents fluid leakage. The first valve room 40a formed between the first and second body blocks 10a and 10b has valve seats 41a and 43a that are formed on facing inner surfaces at front and rear sides and are aligned with each other. The first valve room 40a communicates with the supply port P through a valve hole 42a of the valve seat 41a, and communicates with the exhaust port Ra through a valve hole 44a of the valve seat 43a. The first valve room 40a also communicates with the load port A directly passing through substantially a middle point of the first valve room 40a. Although the load port A is formed in the first body block 10a in FIGS. 4A and 4B, it can be formed in the second body block 10b according to a contact position between the first and second body blocks 10a and 10b. Referring to FIG. 5, an interlocking hole 45a connected to the solenoid operation room 17 is formed beside the valve seat 43a at the exhaust port side of the first valve room 40a. The second valve room 40b formed between the second and third body blocks 10b and 10c is symmetric with respect to the first valve room 40a, and has valve seats 41 b and 43b that are formed on facing inner surfaces at front and rear sides and are aligned with each other. The second valve room 40b communicates with the exhaust port Rb through a valve hole 42b of the valve seat 41 b, and communicates with the supply port P through a valve hole 44b of the valve seat 43b. The second valve room 40b also communicates with the load port B directly passing through substantially a middle point of the second valve room 40b. Although the load port B is formed in the second body block 10b, the load port B can be formed in the third body block 10c according to a contact position between the second and third body blocks 10b and 10c. Referring to FIG. 5, an interlocking hole 45b connected to the fluid operation room 60 is formed beside the valve seat 43b at the exhaust port side of the second valve room

40b. First and second valve mechanisms 50a and 50b are respectively inserted together with valve springs 57a and 57b into the first and second valve rooms 40a and 40b. The first and second valve mechanisms 50a and 50b have substantially the same structure and are symmetric with each other. As shown in FIG. 6, each of the first and second valve mechanisms 50a and 50b includes a valve member 51 and a valve holder 54. The valve member 51 is made of an elastic material, such as rubber, and has valve elements 52; 52a, 52b and 53;53a, 53b formed at both ends thereof. A distance between the valve elements 52; 52a, 52b and 53; 53a, 53b formed at both the ends of the valve member 51 is designed to be less than a distance between the valve seats in each valve room within a range not exceeding the stroke of the plunger 23, such that the valve seats 41 a and 41 b at the supply port side and the valve seats 43a and 43b of the exhaust port side of the valve rooms 40a and 40b can be alternately opened and closed. The valve holder 54 are made of a cylindrical synthetic resin material such that the valve member 51 can be fitted into the valve holder 54 and the valve elements 52; 52a, 52b and 53; 53a, 53b can protrude from both the sides of the valve member 51. The valve holder 54 includes a spring support projection 55; 55a, 55b formed on an outer peripheral surface of a body, and an interlocking protrusion 56; 56a, 56b extending from one end of the body. Referring to FIG. 5, the interlocking protrusion 56a of the first valve mechanism 50a contacts the plunger 23 inserted into the solenoid operation room 17 through the interlocking hole 45a, and the interlocking protrusion 56b of the second valve mechanism 50b contacts the piston member 70 inserted into the fluid operation room 60 through the interlocking hole 45b. The valve springs 57a and 57b respectively support the valve mechanisms 50a and 50b in an opposite direction to a pressure of fluid applied to the plunger spring 24 of the solenoid mechanism 20 or to the fluid operation room 60, and have an elastic force weaker than the pressure of the fluid or the elastic force of the plunger spring 24. The fluid operation room 60 formed between the third and fourth body blocks 10c and 10d has a cylindrical sliding surface, and has a rear end communicating with the first valve room 40a through grooves 61 and 62 passing through both the second and third body blocks 10b and 10c such that the fluid operation room 60 can be connected to the supply port P or the exhaust port Ra through the first valve room 40a. The piston member 70 inserted into the fluid operation room 60 maintains sealing with the inner surface of the fluid operation room 60 using a seal member 71 and a pressure seal member 72 respectively wound around a front portion and a rear portion of the piston member 70, and can be moved under a pressure of fluid by the pressure seal member 72. The direct solenoid-operated four-way directional control valve according to the present embodiment is repeatedly operated by controlling an electrical signal applied to the solenoid coil 21 of the solenoid mechanism 20. FIG. 4A illustrates a normal state where no electrical signal is applied to the solenoid coil 21 , and FIG. 4B illustrates a converted state where an electrical signal is applied to the solenoid coil 21. In an initial state as shown in FIG. 4A, the plunger 23 is moved toward the solenoid operation room 17 due to the elastic force of the plunger spring 24. The first valve mechanism 50a having the interlocking protrusion 56a contacting the plunger 23 is pushed by the plunger 23, such that the valve element 52a closely contacts the valve seat 41a at the supply port side of the first valve room 40a to block the valve hole 42a, and the valve element 53a is separated from the valve seat 43a at the exhaust port side of the first valve room 40a to open the valve hole 44a. Accordingly, the first valve room 40a is blocked from the supply port P, and the load port A and the exhaust port Ra are opened to the first valve room 40a. The flow of fluid (compressed air) passing through the first valve room 40a is shown by dotted arrow in FIG. 4A. In the meantime, the fluid operation room 60 communicating with the first valve room 40a is not supplied with fluid and is in an atmospheric pressure state through the exhaust port Ra. The piston member 70 inserted into the fluid operation room 60 is pushed rearward by the interlocking protrusion 56b of the second valve mechanism 50b supported by the valve spring 57b in the second valve room 40b. The valve element 52b of the second valve mechanism 50b is separated from the valve seat 43b at the supply port side of the second valve room 40b to open the valve hole 44b, and the valve element 53b closely contacts the valve seat 41 b to block the valve hole 42b. Accordingly, the second valve room 40b is blocked from the exhaust port Rb, and the supply port P and the load port B are opened to the second valve room 40b. The flow of fluid (compressed air) passing through the second valve room 40b is shown by solid arrow in FIG. 4A. If an electrical signal is applied to the solenoid coil 21 and an electrical thrust is produced, as shown in FIG. 4B, the plunger 23 pushes down the plunger spring 24 and is pulled toward the coil bobbin 22, and the first valve mechanism 50a of the first valve room 40a is moved due to the elastic force of the valve spring 57a, such that the valve element 52a opens the valve hole 42a of the valve seat 41a at the supply port side and the valve element 53a closely contacts the valve seat 43a at the exhaust port side to block the valve hole 44a. Accordingly, the first valve room 40a is blocked from the exhaust port Ra, and the supply port P and the load port A are opened to the first valve room 40a. The flow of fluid (compressed air) passing through the first valve room 40a is shown by solid arrow in FIG. 4B. In the meantime, the fluid operation room 60 communicating with the first valve room 40a is filled with fluid supplied from the supply port P opened to the first valve room 40a, and the piston member 70 inserted into the fluid operation room 60 is moved forward due to a pressure of the fluid filled in the fluid operation room 60. Accordingly, the valve element 52b of the second valve mechanism 50b that has the interlocking protrusion 56b contacting the piston member 70 closely contacts the valve seat 43b at the supply port side of the second valve room 40b to block the valve hole 44b, and the valve element 53b is separated from the valve seat 41 b at the exhaust port side of the second valve room 40b to open the valve hole 42b. Accordingly, the second valve room 40b is blocked from the supply port P, and the load port B and the exhaust port Rb are opened to the second valve room 40b. The flow of fluid passing through the second valve room 40b is shown by dotted arrow in FIG. 4B. The operation of the direct solenoid-operated four-way direction control valve is repeatedly performed according to the control of an electrical signal applied to the solenoid coil 21 , and of course, the valve returns to its initial state during a power cut. In the meanwhile, if the push button 30 is pressed in the initial state as shown in FIG. 4A where any electrical signal is not applied, the plunger 23 is forced to be pushed by the slope portion 31 of the pressed push button 30, and as a result, the valve is converted into the state as shown in FIG. 4b where an electrical signal is applied. This converted state is continued while the push button 30 is pressed. If the push button 30 is no longer pressed, the pushed plunger 23 is restored to its initial state by the plunger spring 24. That is, during a power cut, the valve can be operated by manually pressing the push button 30. Although the valve body and the ports formed under the valve body are fixed to the manifold block, the fixing method of the valve body and the ports or the arrangement of the ports can be varied according to applications. Furthermore, although the present embodiment is applied to a pneumatic type of valve, the present invention can be applied both to the pneumatic type of valve and a hydraulic type of valve that is substantially identical in configuration and principle to the pneumatic type of valve. While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims

What is claimed is: 1. A direct solenoid-operated four-way directional control valve comprising: a valve body including a plurality of ports comprised of one supply port, two load ports, and two exhaust ports through each of which fluid enters and exits, a first valve room through which the supply port, one of the two load ports, and one of the exhaust ports pass, a second valve room through which the supply port, the other one of the two load ports, and the other one of the exhaust ports pass, and a fluid operation room communicating with the first valve room and filled with fluid supplied from the first valve room; a solenoid mechanism coupled to the valve body, driven to produce an electrical thrust using an external electrical signal, and including a plunger moved forward and backward due to the electrical thrust; a first valve mechanism movably accommodated in the first valve room of the valve body and interlocking with the plunger of the solenoid mechanism to alternately open and close the supply port and the exhaust port among the ports passing through the first valve room; a piston member installed in the fluid operation room of the valve body and moved by a pressure of the fluid filled in the fluid operation room; and a second valve mechanism movably accommodated in the second valve room of the valve body and interlocking with the piston member to alternately open and close the supply port and the exhaust port among the ports passing through the second valve room.

2. The four-way directional control valve of claim 1 , wherein the valve body is formed by adhering four body blocks that are separated using the first and second valve rooms and the fluid operation room as borders.

3. The four-way directional control valve of claim 1 , wherein the solenoid mechanism comprises: a solenoid coil excited by an external electrical signal and producing an electrical thrust; a coil bobbin wound with the solenoid coil; the plunger movably inserted into the coil bobbin and pulled by the electrical thrust of the solenoid coil; and a plunger spring elastically restoring the plunger when the electrical thrust of the solenoid coil is removed.

4. The four-way directional control valve of claim 1 , wherein the first valve mechanism comprises: a valve member made of an elastic material and having valve elements formed at both ends thereof to alternately open and close the supply port and the exhaust port passing through the first valve room; a valve holder allowing the valve member to be fitted thereinto, and having an interlocking protrusion that passes through an inner wall of the first valve room and contacts and interlocks with an end of the plunger of the solenoid mechanism; and a valve spring elastically supporting the valve holder and pushing the valve holder in an opposite direction to a pressure of fluid applied to the plunger.

5. The four-way directional control valve of claim 1 , wherein the second valve mechanism comprises: a valve member made of an elastic material and having valve elements formed at both ends thereof to alternately open and close the supply port and the exhaust port passing through the second valve room; a valve holder allowing the valve member to be fitted thereinto and having an interlocking protrusion that passes through an inner wall of the second valve room and contacts and interlocks with the piston member of the fluid operation room; and a valve spring elastically supporting the valve holder and pushing the valve holder in an opposite direction to the pressure of the fluid applied to the piston member.

6. The four-way directional control valve of claim 1 , wherein the fluid operation room has a cylindrical sliding surface, and includes a pressure seal member wound around the piston member to maintain sealing with the sliding surface and receiving the pressure of the fluid to be moved together with the piston member.

7. The four-way directional control valve of claim 1 , further comprising a push button pushably installed in the valve body and pushing the plunger of the solenoid mechanism according to its push operation.

8. The four-way directional control valve of claim 4 or 5, wherein each of the first valve room and the second valve room has valve holes respectively connected to the supply port and the exhaust port passing threrethrough, and also has valve seats that can closely contact the valve elements to block the valve holes.