JP2009019684A - Servo valve and actuator using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a servo valve which can move a spool to a given position by air pressure irrespective of a gravitational direction even at the time of power failure and can make an actuator operate at a safety side for actuator positioning. <P>SOLUTION: There is provided a servo valve 100 equipped with a spool 10 having first and second valve bodies 11, 12, and a sleeve 20 which houses the spool movably in an axial direction and has an air feeding port 30 for feeding air to a portion between the first and second valve bodies. In the servo valve, the first and second valve bodies 11, 12 have pressure receiving surfaces 11a, 12a for receiving air pressure caused by air from the feeding port. Then, an area of the pressure receiving surface of the first valve body is formed larger than that of the second valve body, while the spool moves to a direction of the first valve body by feeding the air. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a servo valve and an air actuator using the servo valve, and more particularly to a servo valve in which a spool moves in an axial direction by supplying air.

  Conventionally, a spool having a valve body in a sleeve is used, a voice coil motor is used as an actuator, the spool is moved in the axial direction by controlling the current value, and a piston or the like is provided depending on the position of the valve body. A servo valve that controls the flow rate of air supplied to an actuator and controls a piston or the like of the air actuator is known (for example, see Patent Document 1).

  FIG. 7 is a view showing an air actuator 250 including a conventional servo valve 200. In FIG. 7, the servo valve 200 houses a spool 210 in a sleeve 220 so as to be movable in the axial direction. The spool 210 includes valve bodies 211, 212, and 213 arranged in the axial direction. The sleeve 220 includes a supply port 230, a load port 231, and an exhaust port 232. The actuator unit 90 of the air actuator 250 houses the piston 50 in the cylinder 60, and the piston 50 has a piston head 51 and a piston rod 52. The cylinder 60 and the piston head 51 form a pressure chamber 61, and the piston rod 52 and the cylinder form a pressure chamber 62. The supply port 230 of the servo valve 200 and the pressure chamber 62 are supplied with air of the same pressure from an air pressure source (not shown), and the load port 231 and the pressure chamber 61 communicate with each other.

During normal operation, an actuator (not shown) provided in the servo valve 200 moves the spool 210 in the axial direction by electromagnetic force, opens and closes the load port 231 depending on the position of the valve body 212, and connects the load port 231. By adjusting the inflow / outflow amount of air, the pressure of the pressure chamber 61 is adjusted, and the piston 50 of the actuator unit 90 is driven.
JP 2002-297243 A

  However, in the configuration described in Patent Document 1 described above, since no current is supplied from the actuator at the time of a power failure, the spool moves according to gravity or air pressure, so that the position of the piston of the air actuator becomes an undesired position. There was a risk of moving, and countermeasures were required.

  In the example of FIG. 7, since the pressure receiving areas of the valve bodies 211 and 212, that is, the radial cross-sectional areas are the same, the air pressure due to the air supply is in a balanced state. When the supporting electromagnetic force disappeared, the movement of the spool 210 was influenced by gravity. Therefore, the position of the piston 50 of the actuator unit 90 of the air actuator 250 is determined by the installation direction of the servo valve 200, and for example, the piston 50 stops in a state of protruding. Therefore, in order to move the servo valve to a desired predetermined position during a power failure, it is necessary to install the servo valve 200 and the actuator unit 90 of the air actuator 250 in consideration of the direction of gravity.

  Therefore, the present invention provides a servo valve that can move the spool to a predetermined position by air pressure regardless of the direction of gravity and move the air actuator to the safe side to perform localization even during a power failure. For the purpose.

In order to achieve the above object, a first invention comprises a spool having a first valve body and a second valve body, and the spool is movably accommodated in an axial direction, and the first valve body and the first valve body are accommodated. A servo valve having a sleeve having an air supply port for supplying air between the two valve bodies,
The first valve body and the second valve body each have a pressure receiving surface that receives air pressure by the air supplied from the supply port,
The area of the pressure receiving surface of the first valve body is formed larger than the area of the pressure receiving surface of the second valve body,
The servo valve according to claim 1, wherein the spool moves in the direction of the first valve body by the supply of the air.

  Thereby, even when the control current is not supplied to the actuator of the servo valve due to a power failure or the like, the spool of the servo valve can be moved to a predetermined position by supplying air.

The second invention is the servo valve according to the first invention,
The force that moves in the direction of the first valve body generated by the difference in area of the pressure receiving surface between the first valve body and the second valve body and the air pressure is greater than the gravity acting on the spool. It is large.

  As a result, the spool can always be moved and fixed at a predetermined position regardless of the direction in which gravity is applied.

3rd invention is the servo valve which concerns on 1st or 2nd invention,
The sleeve includes a load port to which a load is connected,
Either the first valve body or the second valve body is disposed at a position to open and close the load port, and the amount of air flowing into and out of the load port is controlled by controlling the position. It is characterized by.

  Thereby, the air inflow / outflow amount of the load port can be controlled to control the operation of the load.

An air actuator according to a fourth invention comprises a servo valve according to the third invention,
A cylinder that supports a piston rod connected to the load port;
The piston rod is moved to a predetermined fixed position according to the amount of air flowing into and out of the load port.

  Thereby, it can be set as the air actuator set so that a piston rod may operate | mov to the safe side and stop at the time of a power failure, and the safety | security at the time of a power failure can be improved.

  According to the present invention, the spool can be moved to a predetermined position even during a power failure, and the safety of the servo valve and the air actuator can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional configuration diagram of a servo valve 100 according to the present embodiment. In FIG. 1, the servo valve 100 according to the present embodiment constitutes a three-way valve, and a magnet case 21 is fixed to the end of a cylindrical sleeve 20. The sleeve 20 is provided with a supply port 30, a load port 31, and an exhaust port 32 that form a three-way valve. The supply port 30 is connected to an air pressure source such as a compressor (not shown), and the load port 31 is connected to a pressure chamber of an air actuator (not shown). Further, the exhaust port 32 is opened to the atmosphere.

  A spool 10 is accommodated in the sleeve 20 and is supported so as to be movable in the axial direction. The spool 10 has three valve bodies 11, 12, and 13. When the spool 10 moves in the axial direction, the valve body 12 opens and closes the ports 30, 31, and 32, and the supply port 30 and the exhaust port 32. The air supply pressure and the exhaust pressure connected to each other can be output to the load port 31 at a rate corresponding to the position of the spool 10.

  The spool 10 is supported in a non-contact manner in the sleeve 20 by a hydrostatic bearing in the radial direction. By supplying air from an air pressure source (not shown), the spool 10 is supported in the sleeve 20 in a non-contact state. A groove 11 b is formed on the surface of the valve body 11, and a groove 13 b is formed on the surface of the valve body 13. These lead the air supply pressure and play a role of stabilizing the non-contact hydrostatic bearing.

  A coil bobbin 14 is formed at one end of the spool 10, and a coil 15 is wound around the coil bobbin 14. A cylindrical permanent magnet 22 is disposed on the surface of the magnet case 21 facing the coil 15. Since the magnet case 21 is made of a magnetic material, the coil 15 is disposed in the magnetic field of the permanent magnet 22. A predetermined current is supplied to the coil 15 from the terminal 16, and the spool 10 can be linearly driven in the axial direction with a driving force corresponding to the current.

  The axial driving force may be controlled according to the axial position of the spool 10. As shown in FIG. 1, the end of the spool 10 opposite to the coil bobbin 14 is provided with a displacement shaft 17 made of a magnetic material, and the sleeve 20 is provided with a detection coil 23 facing the periphery of the displacement shaft 17. You can do it. With such a configuration, a spool position detector can be configured by the displacement shaft 17 and the detection coil 23. For example, if the displacement shaft 17 is made of a magnetic material, the detection coil 23 can output a detection signal corresponding to the position of the displacement shaft 17 from the terminal 24. Therefore, by monitoring the output value of the terminal 24, the position of the spool 10 can be detected and a desired air pressure can be supplied to the air actuator.

  However, only by such axial movement control by electromagnetic force, for example, when a power failure occurs and the current supply to the coil 15 of the coil bobbin 14 is stopped, the position of the spool 10 is moved by gravity. It will be fixed at the position.

  Therefore, in the servo valve 100 according to the present embodiment, the valve bodies 11 and 12 arranged at both ends of the supply port have pressure receiving surfaces 11a and 12a that receive the air pressure by the air supplied from the supply port 30. The pressure receiving surfaces 11a and 12a are formed to have different areas. Thereby, even if the supporting force by the electromagnetic force of the spool 10 disappears due to a power failure, the spool 10 gives a larger force to the larger pressure receiving surfaces 11a and 12a by continuing to supply air from the supply port 30. The spool 10 can be moved in the direction of the valve bodies 11 and 12 having a large area. The pressure receiving surfaces 11 a and 12 a are arranged to face each other so as to sandwich the supply port 30 in order to receive the air pressure supplied from the supply port 30. The difference in radius between the circles forming the pressure receiving surfaces 11a and 12a is only about 50 μm. Therefore, only by visual observation, as shown in FIG. 1, the difference in the area of the pressure receiving surfaces of the valve bodies 11 and 12 cannot be distinguished. Therefore, details will be described later using schematic diagrams.

  FIG. 2 is a diagram illustrating a cross-sectional configuration of an air actuator 150 according to an embodiment to which the servo valve 100 according to the present embodiment is applied.

  2, the air actuator according to the present embodiment includes a cylinder 60, a piston 50, and a servo valve 100 that supplies and exhausts compressed air to and from the cylinder 60. The cylinder 60 is a space for accommodating the piston head 51 of the piston 50, that is, a cylinder body 63 for forming pressure chambers 61 and 62 on both sides of the piston head 51, and for introducing compressed air into the pressure chambers 61 and 62. A passage portion 120 forming an air passage and a guide flange 130 for forming the pressure chamber 62 between the piston 50 and the cylinder body 63 on the rod 52 side are included. Here, the passage portion 120 forms a part of the cylinder 60.

  The passage portion 120 includes an air introduction portion 120-1 having a passage for introducing compressed air, an air passage of the air introduction portion 120-1, a supply port 30 to the servo valve 100, a load port 31, and a cylinder body 63. And two passages 120-2 having passages communicating with the two pressure chambers 61 and 62, respectively. The servo valve 100 is installed and fixed in the passage portion 120. The passage main body 120-2 directly introduces air having a constant pressure introduced in communication with the passage of the air introduction portion 120-1 into the pressure chamber 62 in the cylinder main body 63 and also into the supply port 30 of the servo valve 100. And a passage 120-2b for receiving the air of the adjusted pressure or flow rate from the load port 31 of the servo valve 100 and introducing it into the pressure chamber 61 in the cylinder body 63.

  A hole 110a is formed in the central axis direction on the cylinder head 51 side of the cylinder body 63, and a position sensor rod 410-1 extending in the central axis direction of the piston head 51 is inserted into the hole 110a. A sensor portion 410-2 for detecting the position of the piston 50 is fixed together with the position sensor rod 410-1.

  The cylinder body 63 is provided with a pressure sensor 155 for detecting the pressure in the pressure chamber 62 through a hole 110b communicating with the hole 110a. The cylinder body 63 is further provided with an auxiliary wall member 180 on the lower side in the drawing, and the auxiliary wall member 180 is formed with a passage 180a (only a part of which is shown) communicating with the pressure chamber 61, and on the outlet side. Is provided with a pressure sensor 160 for detecting the pressure in the pressure chamber 61.

  As a control system of the piston 50, a position feedback system by the position sensor 410 including the position sensor rod 410-1 and the sensor unit 410-2 and a pressure feedback system by the pressure sensors 155 and 160 are formed. The control system receives the position command value and the load command value, receives the detection signals from the above-described sensors 410, 155, and 160, and controls the flow rate to the pressure chamber 62 by the servo valve 100. The air actuator 150 can perform highly accurate positioning and load control.

  As described above, when the power failure is not generated and the power is supplied and the normal operation is performed, the air flow rate is controlled by the servo valve 100 based on the operation of the air actuator 150, thereby The position of the piston 50 can be controlled with high accuracy. For example, the servo valve according to the present embodiment may be applied to such an air actuator 150, and safety during a power failure can be improved.

  Next, the operation at the time of a power failure of the servo valve 100 and the air actuator 150 according to the present embodiment that performs the above-described operation at normal time will be described. Since it is during a power failure, the electric drive source does not operate and only air is supplied, so only the movement of air will be described. Even during a power outage, the compressor or the like, which is normally a pneumatic pressure source, is operating and the supply of air is generally continued. In this embodiment, such a state is maintained. Assumed. In the following description, a simplified schematic diagram will be used for easy understanding.

  FIG. 3 is a cross-sectional structure diagram of the servo valve 100 according to the present embodiment and an air actuator 150 to which the servo valve 100 is applied. In FIG. 3, the servo valve 100 according to this embodiment includes a sleeve 20 and a spool 10. The actuator unit 90 of the air actuator 150 includes a cylinder 60 and a piston 50. In the spool 10, three valve bodies 11, 12, and 13 are arranged at predetermined intervals in the axial direction. A coil bobbin 14 is formed on one end of the spool 10.

  The sleeve 20 accommodates the spool 10 so as to be movable in the axial direction, and serves as a casing. The sleeve 20 is provided with a supply port 30, a load port 31 and an exhaust port 32. The supply port 30 is connected to the air pressure source 70 and supplies air having a predetermined air pressure to the servo valve 100. The load port 31 is connected to a pressure chamber 61 formed by the cylinder 60 and the cylinder head 51 of the actuator unit 90 which is a load. The exhaust port 32 is connected to the atmosphere.

  The actuator unit 90 houses the piston 50 in the cylinder 60, the cylinder 60 and the piston head 51 form a pressure chamber 61, and the cylinder 60 and the piston rod 62 form a pressure chamber 62. The pressure chamber 62 is connected to the air pressure source 70 in the same manner as the supply port of the servo valve 100, and is supplied with air having a predetermined air pressure. Further, the load port 31 of the servo valve 100 is connected to the pressure chamber 61 as described above, and the pressure in the pressure chamber 61 is adjusted by the air pressure output from the load port to the pressure chamber 61. The piston 50 moves and is positioned by the pressure balance with 62.

  The supply port 30 of the servo valve 100 is provided between the valve bodies 11 and 12. The valve bodies 11 and 12 receive the air pressure of the air supplied from the supply port 30 at the pressure receiving surfaces 11a and 12a. In FIG. 3, the pressure receiving surfaces 11 a and 12 a are configured such that the pressure receiving surface 11 a of the valve body 11 is larger than the pressure receiving surface 12 a of the valve body 12. That is, when the area of the pressure receiving surface 11a of the valve body 11 is S1 and the area of the pressure receiving surface 12a of the valve body 12 is S2, S1> S2. In FIG. 3, since the valve bodies 11 and 12 are both formed in a cylindrical shape and the pressure receiving surfaces 11a and 12a are both circular, the diameter of the pressure receiving surface 11a is configured to be larger than the diameter of the pressure receiving surface 12a. It will be.

  Here, if the air pressure is P, according to Pascal's law, if pressure is applied to a part of the sealed liquid or gas, the pressure is transmitted to the liquid or gas at the same level. When the force received by the body 11 is Fp1, and the force received by the valve body 12 is Fp2, Fp1 = PS1 and Fp2 = PS2. Here, since S1> S2 as described above, Fp1> Fp2. Accordingly, a force acts in the direction of the valve body 11, and the spool 10 moves toward the valve body 11 and is fixed at the bottom dead center. Then, the air pressure output from the load port 31 is output when the spool 10 reaches bottom dead center. Therefore, if the state of the actuator unit 90 when the spool 10 reaches the bottom dead center is set in advance so as to be in a high safety state, the actuator 90 can be in a safe state even during a power failure. The servo valve 100 can be controlled.

  The shape of the sleeve 20 is such that, as the valve body 11 is enlarged, the inner diameter of the hydrostatic bearing portion 25 at the portion facing the valve body 11 is increased so that the gap between the valve body 11 and the sleeve 20 is maintained. Yes.

  On the contrary, if the area of the pressure receiving surface 12a of the valve body 12 is made larger than the area of the pressure receiving surface 11a of the valve body 11, the relationship between the force Fp1 received by the valve body 11 and the force Fp2 received by the valve body 12 is Fp1 <Fp2, and the spool 10 moves toward the valve body 12 in the event of a power failure. In this case, the spool 10 is fixed at the top dead center. In this case, if the actuator unit 90 is set in a safe state when the spool 10 is at the top dead center, safety during a power failure can be ensured. In this case as well, the inner diameter of the sleeve 20 facing the valve body 12 may be configured to be large, and the clearance between the inner diameter of the valve body 12 and the sleeve 20 may be maintained.

  Thus, by making the areas of the pressure receiving surfaces 11a and 12a of the valve bodies 11 and 12 different, and by making the force acting on the valve bodies 11 and 12 different due to air pressure by air, the valve bodies 11 and 12 are different at the time of power failure. The position of the spool 10 can be set to move to a predetermined position. If the servo valve 100 is installed in a state that is close to the side, or if the pressure by the air is sufficiently large and there is no need to consider the gravity acting on the spool 10, the spool can be placed in a predetermined position even with a slight area difference. 10 can be moved.

  Next, a case where gravity acting on the spool 10 is considered in setting the area difference between the pressure receiving surfaces 11a and 12a of the valve bodies 11 and 12 of the servo valve 10 according to the present embodiment will be described with reference to FIG. FIG. 4 is a simplified cross-sectional structure diagram of the servo valve 100 according to the present embodiment. In FIG. 4, the relationship with the air pressure of the air supplied from the supply port 30 connected to the valve bodies 11 and 12 and the pneumatic pressure source 70 is shown.

  The area of the pressure receiving surface 11a of the valve body 11 is S1, the area of the pressure receiving surface 12a of the valve body 12 is S2, and the supplied air pressure is P. As described above, the force Fp1 received by the pressure receiving surface 11a of the valve body 11 from the air pressure P is Fp1 = PS1, and similarly, the force Fp2 received by the pressure receiving surface 12a of the valve body 12a from the air pressure P is Fp2 = PS2. The force is proportional to the area. Here, the mass of the spool 10 is m, and the upward resultant force acting on the spool 10 is F.

  If it is desired to move the spool 10 in the direction of the valve body 11 in the event of a power failure and fix it at the bottom dead center regardless of the direction of the servo valve 10, the gravity works upward, that is, the servo valve moves up and down in FIG. It may be set so that the formula (1) is established, assuming that it is installed in the direction opposite to the direction and the gravity acts upward.

式（１）を解くと、式（２）のようになり、これを整理すると式（３）のようになる。

Solving equation (1) gives equation (2), and organizing this gives equation (3).

式（３）より、弁体１１の受圧面１１ａと弁体１２の受圧面１２ａの面積差（Ｓ１−Ｓ２）が、ｍｇ／Ｐを超えるように設定すれば良いことが分かる。これはすなわち、エアー圧Ｐにより弁体１１、１２に発生する圧力差（Ｆｐ１−Ｆｐ２）＝Ｐ（Ｓ１−Ｓ２）がスプール１０に作用する重力ｍｇより大きいことを意味している。

From equation (3), it can be seen that the area difference (S1-S2) between the pressure receiving surface 11a of the valve body 11 and the pressure receiving surface 12a of the valve body 12 may be set to exceed mg / P. This means that the pressure difference (Fp1−Fp2) = P (S1−S2) generated in the valve bodies 11 and 12 due to the air pressure P is larger than the gravity mg acting on the spool 10.

  Similarly, when it is desired to move and fix the spool 10 in the direction of the valve body 12 in the event of a power failure, it is assumed that the servo valve 100 is arranged according to the vertical relationship shown in FIG. Assuming the downward direction, the equation (4) may be satisfied.

これを解くと、式（５）のようになり、整理すると式（６）のようになる。

If this is solved, it will become like Formula (5), and it will become like Formula (6) if rearranged.

式（６）からも、やはり弁体１１の受圧面１１ａと弁体１２の受圧面１２ａの面積差（Ｓ２−Ｓ１）が、ｍｇ／Ｐを超えるように設定すれば良いことが分かる。これはすなわち、エアー圧Ｐにより弁体１１、１２に発生する圧力差（Ｆｐ２−Ｆｐ１）＝Ｐ（Ｓ２−Ｓ１）がスプール１０に作用する重力ｍｇより大きいことを意味している。

It can also be seen from equation (6) that the area difference (S2-S1) between the pressure receiving surface 11a of the valve body 11 and the pressure receiving surface 12a of the valve body 12 should be set to exceed mg / P. This means that the pressure difference (Fp2−Fp1) = P (S2−S1) generated in the valve bodies 11 and 12 due to the air pressure P is larger than the gravity mg acting on the spool 10.

  In this way, the areas of the pressure receiving surfaces 11a, 12a of the valve bodies 11, 12 to be moved and fixed at the time of a power failure are made larger than the pressure receiving surfaces 11a, 12a of the other valve bodies 11, 12, and the difference between the areas and the air pressure If the force acting on the valve bodies 11 and 12 generated by P is set to be larger than the gravity acting on the spool 10, it is always moved to a desired fixed position regardless of the direction of gravity of the servo valve 100. Can be fixed. Thereby, at the time of a power failure, control objects, such as piston 50 of actuator part 90, can be moved and fixed to a predetermined fixed position, and it can be set as air actuator 150 in which safety was secured even at the time of a power failure.

  However, in actuality, the mass of the spool 10 is about 100 g, and the difference between the diameters of the pressure receiving surfaces 11a and 12a of the valve bodies 11 and 12 is also about 50 μm. Therefore, the gravity acting on the spool 10 is strictly considered. Even if it is not, there are many cases where this condition is naturally satisfied, and if it is configured so that S1> S2 or S1 <S2, it may naturally satisfy the condition of the expression (1) or (4). Many.

  Next, the operation at the time of a power failure of the servo valve 100 and the air actuator 150 according to the present embodiment in consideration of the relationship with the operation of the actuator unit 90 of the air actuator 150 will be described with reference to FIGS.

  FIG. 5 is a cross-sectional configuration diagram when the area of the pressure receiving surface 11a of the valve body 11 is larger than the area of the pressure receiving surface 12a of the valve body 12 of the air actuator 150 including the servo valve 100 according to the present embodiment. In FIG. 5, the individual components are the same as those described so far, and the description thereof is omitted. Further, as described with reference to FIG. 4, it is assumed that the gravity acting on the spool 10 is set in consideration.

  In FIG. 5, since the area S1 of the pressure receiving surface 11a of the valve body 11 is larger than the area S2 of the pressure receiving surface 12a of the valve body 12, the spool 10 moves in the direction of the valve body 11 (downward in the figure) at the time of power failure. To do. At this time, the valve body 12 opens the upper side (the valve body 13 side) of the load port 31 to create a passage that communicates the load port 31 and the exhaust port 32. Therefore, the load port 31 that communicates with the pressure chamber 61 formed by the cylinder 60 and the piston head 51 creates an air passage that communicates from the pressure chamber 61 to the exhaust port 32 via the load port 31, and the air in the pressure chamber 61 is loaded. The gas flows out of the port 31 and flows into the exhaust port 32 and is discharged from the exhaust port 32 to the atmosphere. Therefore, the pressure in the compression chamber 61 decreases. On the other hand, since the constant pressure air is supplied from the air pressure source 70 to the pressure chamber 62 maintaining the pressure balance via the piston head 51, the pressure is constant. Therefore, the piston 50 is raised by the force acting on the pressure chamber 61 from the pressure chamber 62. By such an operation, the piston rod 52 rises, moves in a contracting direction, and is localized at the top dead center. That is, in this case, the fixed position where the piston rod 52 moves is the top dead center position, and the air actuator 150 is configured so that the piston rod 52 moves in the returning direction.

  For example, when it is desired that the piston rod 52 be contracted during a power failure, the pressure chamber 61 on the piston head 51 side may be configured to be depressurized.

  Next, the air actuator 150 including the servo valve 100 according to the present embodiment when the spool 10 is moved in the direction of the valve body 12 (upward in the figure) at the time of a power failure will be described with reference to FIG. FIG. 6 is a cross-sectional configuration diagram of the air actuator 150 including the servo valve 100 according to the present embodiment when the area of the pressure receiving surface 12a of the valve body 12 is configured to be larger than the area of the pressure receiving surface 11a of the valve body 11. is there.

  In FIG. 6, the diameter of the valve body 12 is larger than the diameter of the valve body 11, so that the inner diameter of the sleeve 20 facing the valve body 12 is large, which is different from the previous embodiments. ing. Other components are the same as those described above.

  In FIG. 6, at the time of a power failure, the area of the pressure receiving surface 12 a of the valve body 12 is larger than the area of the pressure receiving surface 11 a of the valve body 11, so the spool 10 moves in the direction of the valve body 12. Then, the lower side of the load port 31 (the valve body 11 side) opens, and the air supplied from the supply port 30 enters the pressure chamber 61 formed by the cylinder 60 and the piston head 51 of the actuator unit 90 via the load port 31. An inflow passage is formed. Therefore, air flows into the pressure chamber 61 via the load port 31 and the pressure rises. On the other hand, a constant pressure of air is supplied from the air pressure source 70 to the pressure chamber 62 that maintains a pressure balance with the pressure chamber 61 via the piston head 51, and the pressure is constant. Therefore, the pressure in the pressure chamber 61 becomes higher than the pressure in the pressure chamber 62, and the piston rod 52 moves in the protruding direction. When the piston 50 reaches the bottom dead center, the piston rod 52 is fixed. Thus, when it is desired to set the fixed position so that the piston 50 is fixed at the bottom dead center during a power failure, the diameter of the valve body 12 may be formed larger than the diameter of the valve body 11.

  Thereby, it can be set as the air actuator 150 which localizes in the state which the piston rod 52 fell at the time of a power failure.

  In the present embodiment, the actuator unit 90 of the air actuator 150 is described as an example in which the actuator composed of the cylinder 60 and the piston 50 is taken as an example, and the pressure chamber 61 on the piston head 51 side is connected to the load port 31. However, various modes can be applied to the type and type of the actuator unit 90 and the connection method of the servo valve 100 with the load port 31.

  Further, as can be seen from the above description, the first valve body and the second valve body in the claims are both set to the first valve body and the first valve body, respectively, according to the setting method. It can be applied as a second valve body.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

It is a section lineblock diagram of servo valve 100 concerning this example. It is a section lineblock diagram of air actuator 150 concerning this example. 1 is a cross-sectional structure diagram of a servo valve 100 according to an embodiment and an air actuator 150 to which the servo valve 100 is applied. It is the simplified cross-section figure of the servo valve 100 which concerns on a present Example. It is a section lineblock diagram in case the diameter of valve body 11 is larger than the diameter of valve body 12 of air actuator 150 containing servo valve 100 concerning this example. It is a section lineblock diagram in case the diameter of valve body 11 is larger than the diameter of valve body 12 of air actuator 150 containing servo valve 100 concerning this example. It is the figure which showed the air actuator 250 containing the conventional servo valve 200. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Spool 11, 12, 13 Valve body 11a, 12a Pressure receiving surface 14 Coil bobbin 15, 23 Coil 16, 24 Terminal 17 Displacement shaft 20 Sleeve 21 Magnet case 22 Permanent magnet 25 Static pressure bearing part 30 Supply port 31 Load port 32 Exhaust port 50 Piston 51 Piston head 52 Piston rod 60 Cylinder 61, 62 Pressure chamber 70 Air pressure source 90 Actuator part 100 Servo valve 110a, 110b Hole 120 Passage part 120-1 Air introduction part 120-2 Passage body part 120-2a, 120-2b , 180a passage 130 guide flange 150 air actuator 155, 160 pressure sensor 180 auxiliary wall member 410 position sensor 410-1 position sensor rod 410-2 sensor unit

Claims (4)

A spool having a first valve body and a second valve body, and a supply for accommodating the spool so as to be movable in the axial direction and supplying air between the first valve body and the second valve body A servo valve with a sleeve having a port,
The first valve body and the second valve body each have a pressure receiving surface that receives air pressure by the air supplied from the supply port,
The area of the pressure receiving surface of the first valve body is formed larger than the area of the pressure receiving surface of the second valve body,
The servo valve according to claim 1, wherein the spool moves in the direction of the first valve body by the supply of the air.   The force that moves in the direction of the first valve body generated by the difference in area of the pressure receiving surface between the first valve body and the second valve body and the air pressure is greater than the gravity acting on the spool. The servo valve according to claim 1, wherein the servo valve is large. The sleeve includes a load port to which a load is connected,
Either the first valve body or the second valve body is disposed at a position to open and close the load port, and the amount of air flowing into and out of the load port is controlled by controlling the position. The servo valve according to claim 1 or 2, wherein A servo valve according to claim 3;
A cylinder that supports a piston rod connected to the load port;
The air actuator according to claim 1, wherein the piston rod is moved to a predetermined fixed position by an amount of air flowing into and out of the load port.

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