JP7838793B2 - Gas pressure servo valve - Google Patents

Description

This disclosure relates to a gas pressure servo valve.

Conventionally, a nozzle-flapper type hydraulic servo valve, as described in Patent Document 1, is known as a servo valve. This hydraulic servo valve comprises a first nozzle, a second nozzle facing the first nozzle, a flapper positioned to pass between the first and second nozzles, and a spool movable in the axial direction. This hydraulic servo valve further comprises a first hydraulic chamber located at one axial end of the spool and a second hydraulic chamber located at the other axial end of the spool. The first nozzle communicates with the first hydraulic chamber, and the back pressure of the first nozzle matches the hydraulic pressure of the first hydraulic chamber. The second nozzle communicates with the second hydraulic chamber, and the back pressure of the second nozzle matches the hydraulic pressure of the second hydraulic chamber.

This servo valve changes the back pressure at the first and second nozzles by changing the position of the flapper. This change in back pressure then alters the force acting on the spool from both ends, causing the spool to move axially and thus opening and closing the valve. A feedback spring connects the flapper and the spool. When the spool moves from its neutral position due to the change in the flapper's position, the feedback spring deflects, applying force to the flapper towards the neutral position. When the back pressure difference at both ends of the spool disappears, the feedback spring causes the flapper to rest in the neutral position, and the spool also rests in the neutral position.

Japanese Patent Publication No. 2000-032731

Using gas as the working fluid in a fluid servo valve offers superior versatility compared to hydraulic systems, as it eliminates the risk of fluid leakage damaging mounted equipment. However, in fluid servo valves integrating a flapper and feedback spring, using gas as the fluid can sometimes lead to oscillation due to differences between compressible gas and incompressible oil. Furthermore, particularly in small fluid servo valves, minute vibrations may occur. If these minute vibrations can be suppressed quickly, a highly versatile, compact, and high-performance servo valve can be realized. Therefore, the objective of this disclosure is to provide a gas pressure servo valve that is easily able to suppress vibrations quickly.

To solve the above problems, the gas pressure servo valve according to this disclosure comprises a sleeve having two gas supply ports, an exhaust port, and two output ports; a spool slidable within the sleeve; pressure chambers provided on both sides of the spool in the axial direction; a pressure difference generation mechanism that generates a pressure difference between the pressure in one of the pressure chambers on the axial side of the spool and the pressure in the other pressure chamber on the axial side of the spool; a feedback spring connecting the pressure difference generation mechanism and the spool; and a tank communicating with each of the pressure chambers via a vibration damping passage, wherein the inner surface of the vibration damping passage includes a first planar portion and a second planar portion substantially parallel to the first planar portion, and the distance between the first planar portion and the second planar portion is 100 μm or less.

The inventors have confirmed that when a gas is placed at a distance of 100 μm or less and passes between two substantially parallel planar sections (first and second planar sections), vibrations can be significantly attenuated compared to when the gas passes through an orifice with vibration damping effects. In one experimental example, vibrations were found to be significantly reduced to less than 1/5. Therefore, according to this disclosure, a gas pressure servo valve that can easily dampen vibrations in a short time can be realized.

Furthermore, in this disclosure, the first planar portion is included in a side wall portion having a communication hole that communicates with both the pressure chamber and the vibration damping channel, and the second planar portion is included in a flat plate member. The invention may further include a plurality of annular shims sandwiched between the side wall portion and the flat plate member and arranged at intervals from each other, and fastening means having a shaft portion that penetrates the through-holes of each shim and fastens the flat plate member to the side wall portion.

With this configuration, the distance between the first and second planar sections can be easily and precisely adjusted simply by adjusting the thickness of the shim. Therefore, a gas pressure servo valve with the desired damping characteristics can be manufactured simply and inexpensively.

Furthermore, in this disclosure, the first planar portion may be included in a side wall portion having a communication hole that communicates with both the pressure chamber and the vibration damping channel, and the second planar portion may be included in a flat plate member, and the vibration damping channel may have a plurality of vibration damping channel portions extending in the radial direction of the communication hole.

In this specification, the radial direction is defined as a linear direction that is substantially perpendicular to the extending direction of the communication hole and intersects the communication hole in a plan view from outside the extending direction of the communication hole. Therefore, in this disclosure, the radial direction can be defined even when, for example, the communication hole has a rectangular cross-sectional shape.

This configuration allows the tank to be installed outside the sleeve, thus increasing the length of the vibration damping passage and the tank capacity, thereby enhancing the vibration damping effect. Furthermore, since the vibration damping passage has multiple vibration damping passage sections, this also contributes to the enhanced vibration damping effect. Therefore, the synergistic effect of these factors results in superior vibration damping performance.

Furthermore, in this disclosure, the width of each vibration-damping channel may be substantially constant.

This configuration allows for nearly identical vibration damping performance when the gas flows from the pressure chamber to the tank, and when the gas flows from the tank to the pressure chamber. Therefore, depending on the specifications, higher vibration damping performance may be possible.

Furthermore, in this disclosure, the width of each vibration-damping channel may increase as it moves radially outward.

This configuration allows for a reduction in gas flow velocity when the gas flows from the pressure chamber to the tank, thereby reducing noise.

Furthermore, in this disclosure, one of the surfaces of the side wall portion facing the flat plate member and the surface of the flat plate member facing the side wall portion may have a plurality of grooves extending in the radial direction, and the plurality of vibration damping flow channels may be defined by the other of the surfaces of the side wall portion facing the flat plate member and the surface of the flat plate member facing the side wall portion closing the openings in the depth direction of the plurality of grooves.

According to this configuration, a vibration-damping channel with high vibration damping performance can be easily and inexpensively formed by simply creating multiple shallow grooves with a depth of 100 μm or less on either the side surface of the flat plate member or the side surface of the flat plate member using etching or the like.

Furthermore, in this disclosure, the flat plate member may have a disc shape, and the center of the flat plate member may be directly opposite the approximate center of the communication hole in the thickness direction of the flat plate member.

This configuration makes it easy to form multiple vibration-damping channel sections of approximately the same length. Therefore, it is easier to reduce noise and achieve high vibration damping performance.

Furthermore, the tank may have an annular opening or a plurality of openings arranged circumferentially on a cylindrical surface.

According to this configuration, even when there are multiple vibration-damping flow channels extending radially in different directions, the gas from the multiple vibration-damping flow channels can be easily flowed into the tank.

Furthermore, in this disclosure, the tank may consist of an internal chamber provided inside the spool, and the spool may have a communication hole connecting the internal chamber and the vibration-damping channel.

This configuration makes it easy to create a compact gas pressure servo valve with high vibration damping performance.

According to this disclosure, a gas pressure servo valve that can easily dampen vibrations in a short time can be realized.

A schematic cross-sectional view of a gas pressure servo valve according to one embodiment of the present disclosure. This diagram illustrates the operation of the pressure difference generation mechanism. This diagram illustrates the operation of the pressure difference generation mechanism. This diagram illustrates the operation of the pressure difference generation mechanism. This is a schematic cross-sectional view illustrating the operation of a gas pressure servo valve. This is a schematic cross-sectional view illustrating the operation of a gas pressure servo valve. This is an enlarged cross-sectional view of the first vibration damping channel and the area around the first tank in Figure 1. This diagram illustrates the method for forming the first vibration control channel. This is a plan view of a flat plate member as seen from the first side wall, with all fastening means inserted and the shafts of each fastening means passing through the through holes in the shims. This is a schematic cross-sectional view corresponding to Figure 7 in the gas pressure servo valve of the reference example. This is a plan view showing the surface of the first side wall portion in a modified example of a flat plate member. This is a plan view corresponding to Figure 11 of a flat plate member in another modified example. This is a plan view corresponding to Figure 11 of a flat plate member in another modified example. A schematic axial cross-sectional view of another modified gas pressure servo valve. This is a schematic cross-sectional view of the spool area of another modified gas pressure servo valve.

The embodiments relating to this disclosure will be described in detail below with reference to the attached drawings. Note that if multiple embodiments or modifications are included below, it is intended from the outset that new embodiments may be constructed by appropriately combining their characteristic features. Furthermore, in the following embodiments, the same reference numerals are used for the same components in the drawings, and redundant explanations are omitted. Also, multiple drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. Furthermore, among the components described below, components not described in the independent claim indicating the highest-level concept are optional components and not essential components. Also, any gas may be used in the pressure servo valve, but air or an inert gas can be suitably used as the gas; examples of inert gases include argon and nitrogen. Furthermore, in the following description and drawings, the X direction is the axial direction of the spool 5, and the Y direction is the direction in which the flapper 21 extends in the neutral position described below. The X direction is perpendicular to the Y direction. Furthermore, in the following, the radial direction is defined as a straight line that is approximately perpendicular to the extending direction of the communication hole 43 described below, and intersects the communication hole 43 in a plan view from outside the extending direction of the communication hole 43. Therefore, the radial direction can be defined regardless of the cross-sectional shape of the communication hole 43. Also, the inner side of the radial direction refers to the side of the communication hole in the radial direction, and the outer side of the radial direction refers to the side away from the communication hole in the radial direction.

Figure 1 is a schematic cross-sectional view of a gas pressure servo valve 1 according to one embodiment of the present disclosure, when cut in a plane including the X and Y directions. As shown in Figure 1, the gas pressure servo valve 1 is a nozzle flapper type servo valve. The gas pressure servo valve 1 comprises a cover 2, a lower housing 3, a pressure difference generation mechanism 4, a spool 5, a feedback spring 6, a first vibration damping passage 7, a second vibration damping passage 8, a first nozzle 9, a second nozzle 10, a sleeve 11, a first pressure chamber 12, a second pressure chamber 13, a first tank 18, and a second tank 19.

The pressure difference generation mechanism 4 includes an armature 20, a flapper 21, a first coil 22, a second coil 23, a first back pressure path 15, a second back pressure path 16, an upper magnetic pole 25 with a U-shaped cross-section, and a lower magnetic pole 26 with a U-shaped cross-section. The armature 20 and the flapper 21 are integrated to form a T-shaped armature-flapper. The armature 20 is a magnetic arm that extends elongated in the Y direction in the neutral position. The upper magnetic pole 25 and the lower magnetic pole 26 are positioned opposite each other in the Y direction with a gap between them, such that the recesses 25a of the upper magnetic pole 25 and 26a of the lower magnetic pole 26 face each other in the Y direction. The ends 20a and 20b of the armature 20 are positioned between the magnetic gap formed by the pole portion 25b of the upper magnetic pole 25 and the pole portion 26b of the lower magnetic pole 26.

The first coil 22 is wound on one side of the center of the armature 20, and the second coil 23 is wound on the other side of the center of the armature 20. Four lead wires extending from the first coil 22 and the second coil 23 are brought out to the outside of the gas pressure servo valve 1 and electrically connected to a drive circuit 28 included in a control device (not shown). The pressure difference generation mechanism 4 is driven by the drive circuit 28 controlled by the control device.

The flapper 21 is a hollow tube that extends in the Y direction in the neutral position, spanning the internal space of the cover 2 and the internal space of the lower housing 3. The feedback spring 6 has a portion located inside the hollow tube of the flapper 21 and is an elastic shaft that extends in the Y direction in the neutral position. The upper end of the feedback spring 6 is fixed to the inner circumferential surface of the hollow flapper 21, and the lower end of the feedback spring 6 is connected to the central part of the spool 5.

Next, the operation of the pressure difference generation mechanism 4 will be explained using Figures 2 to 4. As shown in Figure 2, for example, the two poles (ends) 25b of the upper magnetic pole 25 are polarized to the north pole, and the two poles (ends) 26b of the lower magnetic pole 26 are polarized to the opposite south pole. Here, by controlling the direction of the current flowing through the two coils 22 and 23, opposite magnetic poles can be generated at one end 20a and the other end 20b of the armature 20 according to the right-hand rule. By controlling the direction of the current flowing through the two coils 22 and 23, as shown in Figure 3, a force can be applied to one end 20a and the other end 20b in the direction indicated by arrow A or arrow B, based on the attractive and repulsive forces acting between the upper magnetic pole 25 and the lower magnetic pole 26.

Therefore, as shown in Figure 4, the armature 20 can be rotated around the fixed center S as a pivot point in either the clockwise direction indicated by arrow C or the counterclockwise direction indicated by arrow D. The flapper 21 can also be rotated from its neutral position, which extends in the Y direction perpendicular to the X direction, around the fixed center S as a pivot point in either the clockwise direction indicated by arrow C or the counterclockwise direction indicated by arrow D. As a result, the flapper 21 and feedback spring 6 can be tilted from the neutral position to one or the other side in the X direction. Note that when no current flows through both coils 22 and 23, the armature 20 is not magnetized, no force acts between the armature 20 and the upper magnetic pole 25 and lower magnetic pole 26, and the armature 20 extends parallel to the X direction. The position of the armature 20 when no current flows through both coils 22 and 23 is the neutral position.

Referring again to Figure 1, the first nozzle 9 and the second nozzle 10 extend in the X direction. The first nozzle 9 and the second nozzle 10 are positioned facing each other with the flapper 21 in between. The first nozzle 9 and the second nozzle 10 eject gas from a gas supply source having a predetermined supply gas pressure Ps from their tip nozzle openings along the X direction into the flapper 21. A first fixed constrictor 30 is provided between the gas supply source and the first nozzle 9, and a second fixed constrictor 31 is provided between the gas supply source and the second nozzle 10. Therefore, the first nozzle 9 and the second nozzle 10 are supplied with gas from a gas supply source having a predetermined supply gas pressure Ps, after being constricted by the first fixed constrictor 30 and the second fixed constrictor 31. A first back pressure passage 15 branches off from between the first fixed constrictor 30 and the first nozzle 9, and a second back pressure passage 16 branches off from between the second fixed constrictor 31 and the second nozzle 10.

The sleeve 11 is a cylindrical member positioned within the internal space of the lower housing 3. The cylindrical inner wall surface of the sleeve 11 is precisely machined to define a spool sliding space that slidably supports the spool 5. While the cross-sectional shape of the cylindrical inner wall surface may be rectangular or other, the case of a circular cross-section will be described. Therefore, the sleeve 11 has an inner wall surface with a circular through-hole, and the spool 5 slides within this circular hole. The first pressure chamber 12 is provided on one side of the spool 5 in the X direction within the lower housing 3, and the second pressure chamber 13 is provided on the other side of the spool 5 in the X direction within the lower housing 3. The first back pressure passage 15 communicates with the first pressure chamber 12, and the second back pressure passage 16 communicates with the second pressure chamber 13.

The sleeve 11 has four types of ports through which gas flows between its outer and inner surfaces. Specifically, the sleeve 11 has a first gas supply port Ps1, a second gas supply port Ps2, a first output port CY1, a second output port CY2, and an exhaust port Ex. On the bottom surface of the lower housing 3, four external connection ports (not shown) are provided, corresponding to the first gas supply port Ps1, the second gas supply port Ps2, the first output port CY1, the second output port CY2, and the exhaust port Ex in the sleeve 11. The reason the five ports of the sleeve 11 correspond to the four external connection ports is that two passages communicating with the gas supply ports Ps1 and Ps2 are connected within the lower housing 3 to form a single passage.

External connection ports corresponding to gas supply ports Ps1 and Ps2 are connected to a gas supply source (not shown), and gas at a predetermined supply gas pressure Ps is supplied to the gas pressure servo valve 1. Two external connection ports corresponding to the first output port CY1 and the second output port CY2 are connected to two input ports of an external load (not shown). The external load is, for example, a gas pressure valve equipped in various devices. The gas used by the gas pressure servo valve 1 is exhausted through the external connection port corresponding to the exhaust port Ex. The exhausted gas is returned to the recovery tank or released directly into the atmosphere.

The spool 5 is a shaft having multiple lands with multiple outer diameters that can slide along the inner wall surface of the through-hole of the sleeve 11, and multiple stems with smaller outer diameters than the lands that connect adjacent lands. The spool 5 has a first land 34, a second land 35, a third land 36, and a fourth land 37. The lower end of the feedback spring 6 is connected to the center of the stem 39 between the second land 35 and the third land 36. Gas pressure chambers are formed between each of the lands 34-37.

In the neutral position shown in Figure 1, three gas pressure chambers are formed between the sleeve 11 and the spool 5. Specifically, in the neutral position, the second land 35 closes the first output port CY1 of the sleeve 11, and the third land 36 closes the second output port CY2 of the sleeve 11. Furthermore, in the neutral position, the gas pressure chamber between the first land 34 and the second land 35 communicates with the first gas supply port Ps1 of the sleeve 11, and the gas pressure chamber between the third land 36 and the fourth land 37 communicates with the second gas supply port Ps2 of the sleeve 11. Also in the neutral position, the gas pressure chamber between the second land 35 and the third land 36 communicates with the exhaust port Ex of the sleeve 11.

In the above configuration, the gas pressure servo valve 1 performs the opening and closing operation as follows. First, in the neutral position, no drive current is supplied to the coils 22 and 23 from the control device's drive circuit 84, and the armature 20 is not magnetized. The flapper 21 is located midway between the first nozzle 9 and the second nozzle 10. Therefore, even when gas at supply pressure Ps is supplied from the gas supply source to the first nozzle 9 and the second nozzle 10, the back pressure of the first nozzle 9 and the back pressure of the second nozzle 10 are the same, and the atmospheric pressure in the first pressure chamber 12 and the second pressure chamber 13 are the same. Thus, the spool 5 is in the neutral position where the feedback spring 6 extends parallel to the Y direction. As a result, the first output port CY1 is closed by the second land 35, and the second output port CY2 is closed by the third land 36.

On the other hand, suppose a current is passed through coils 22 and 23 in a direction that causes the armature 20 to tilt in the direction indicated by arrow A in Figure 3. Then, as shown in Figure 5, the armature 20 rotates in the direction indicated by arrow A, and consequently, the flapper 21, which is integrated with the armature 20, rotates around its center of rotation. The flapper 21 moves closer to the second nozzle 10 than its neutral position, and further away from the first nozzle 9 than its neutral position. Consequently, the back pressure of the first nozzle 9 and the back pressure of the second nozzle 10 change, and in the example in Figure 5, (back pressure of the second nozzle 10) > (back pressure of the first nozzle 9). The back pressure of the first nozzle 9 is led to the first pressure chamber 12 by the first back pressure passage 15, and the back pressure of the second nozzle 10 is led to the second pressure chamber 13 by the second back pressure passage 16.

This creates a pressure difference at both ends of the spool 5 in the axial direction. As a result, the spool 5 moves axially in accordance with this pressure difference, and in the example shown in Figure 5, it moves to the right side of the plane of the paper in the X direction. This movement causes the third land 36 to open the second output port CY2, and the second gas supply port PS2 to communicate with the second output port CY2. Furthermore, the second land 35 opens the first output port CY1, and the exhaust port Ex communicates with the first output port CY1.

As the spool 5 moves to the right in the X direction, the lower end of the feedback spring 6 also moves to the right in the X direction. This causes the feedback spring 6 to bend to the right in the X direction, resulting in an elastic reaction force acting to the left in the X direction. In other words, the elastic reaction force of the feedback spring 6 acts to return the spool 5 to the left in the X direction. When the force on the armature 20 from the flapper 21 due to the distortion of the feedback spring 6 in the X direction to the right matches the force on the armature 20 from the upper magnetic pole 25 and lower magnetic pole 26 in the X direction to the left, the armature 20 comes to rest and the spool 5 reaches a balanced state, causing the spool 5 to come to rest.

Figure 6 shows the balanced state where the movement of the spool 5 in the X direction has stopped. In the balanced state, gas flows into the second output port CY2 from the second gas supply port PS2 side at a flow rate Q corresponding to the opening degree of the second output port CY2, which is determined at the position of the third land 36 in the balanced state. The flow rate Q is a value corresponding to the drive current supplied from the drive circuit to coils 22 and 23. Furthermore, at the first output port CY1, exhaust is performed from the load side toward the exhaust port Ex, according to the opening degree of the first output port CY1, which is determined at the position of the second land 35 in the balanced state.

Furthermore, if the armature 20 rotates in the direction indicated by arrow B in Figure 3, the only difference from the case described in Figures 5 and 6 is that the spool 5 moves to the left in the X direction instead of to the right in the X direction. The operation is the same as described in Figures 5 and 6. In this case, the first output port CY1 communicates with the first gas supply port PS1, and the second output port CY2 communicates with the exhaust port Ex.

Next, the structure of the first vibration damping channel 7 and the first tank 18 will be described. Note that the structure of the second vibration damping channel 8 and the second tank 19 is the same as that of the vibration damping channel 7 and the first tank 18, so their description will be omitted. Figure 7 is an enlarged cross-sectional view of the area around the first vibration damping channel 7 and the first tank 18 in Figure 1. As shown in Figure 7, the side wall 40 defining the inner surface of the first pressure chamber 12 in the X direction has a first side wall portion 41 and a second side wall portion 42. The first side wall portion 41 has a communication hole 43 that communicates with both the first pressure chamber 12 and the first vibration damping channel 7 and extends in the X direction. In this embodiment, the communication hole 43 is a cylindrical hole, but the communication hole 43 may have any shape; for example, its cross-sectional shape may be rectangular.

The gas pressure servo valve 1 includes a disc-shaped disk 45, which is an example of a flat plate member. The outer surface 41a of the first side wall 41, opposite to the first pressure chamber 12, is a plane substantially perpendicular to the X direction. The disk 45 is fixed to the first side wall 41 by fastening means (e.g., bolts) 46, with its center facing the center of the communication hole 43 in the X direction. More specifically, as shown in Figure 8, the disk 45 is fixed to the first side wall 41 by multiple fastening means 46 arranged at intervals in the circumferential direction and located at substantially the same radial position. This fixing is performed with an annular shim 48 sandwiched between the outer surface 41a of the first side wall 41 and the disk 45.

The shaft portion 46a of each fastening means 46 passes through the through hole 48a of the shim 48. The surface of the disk 45 facing the outer surface 41a is a flat surface 45a, which is approximately perpendicular to the X direction. The outer surface 41a is approximately parallel to the flat surface 45a. A gap in the X direction, corresponding to the thickness of the shim 48, is created between the outer surface 41a of the first side wall portion 41 and the flat surface 45a of the disk 45. This gap in the X direction is set to 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less, and most preferably 20 μm or less (for example, 5 μm to 15 μm). The portion of the outer surface 41a that faces the flat surface 45a and not the shim 48 constitutes the first flat portion 55, and the portion of the flat surface 45a that faces the outer surface 41a and not the shim 48 constitutes the second flat portion 56.

Figure 9 is a plan view of the disk 45 as seen from the first side wall 41, with all fastening means 46 inserted and the shafts 46a of the fastening means 46 passing through the through holes 48a of the shims 48. In Figure 9, the area 80 enclosed by the dotted circle is the area facing the communication hole 43 in the X direction. As shown in Figure 9, a vibration damping channel 7 exists between the circumferentially adjacent shims 48 between the outer surface 41a and the disk 45, through which gas flows.

In the example shown in Figure 9, since there are three shims 48 arranged at equal intervals in the circumferential direction, the vibration damping channel 7 has three vibration damping channel sections 7a located at equal intervals in the circumferential direction. Each vibration damping channel section 7a extends approximately in the radial direction. As shown in Figure 7, the second side wall 42 has a disc-shaped recess 42a on the planar portion facing the first side wall 41. The inner diameter of this recess 42a is larger than the outer diameter of the disk 45, and the depth of the recess 42a is greater than the thickness of the disk 45. The second side wall 42 is fixed in close contact with the first side wall 41 with the central axis of the recess 42a approximately coinciding with the central axis of the disk 45.

Therefore, as shown in Figure 7, a chamber with a roughly U-shaped cross-section is formed within the side wall 40. This chamber constitutes the first tank 18. The first tank 18 has a cylindrical outer surface 18a. The first tank 18 also has an annular opening 18b. With this configuration, the first pressure chamber 12 communicates with the first tank 18 via the communication hole 43 and the vibration damping channel 7. As shown in Figure 7, the gas pressure servo valve 1 includes a first O-ring 61 and a second O-ring 62. The first O-ring 61 prevents gas from leaking between the lower housing 3 (see Figure 1) and the first side wall 41, and the second O-ring 62 prevents gas from leaking between the first side wall 41 and the second side wall 42.

The gas pressure servo valve 1 comprises a sleeve 11 having two gas supply ports PS1 and PS2, an exhaust port Ex, and two output ports CY1 and CY2; a spool 5 slidable within the sleeve 11; pressure chambers 12 and 13 provided on both sides of the spool 5 in the axial direction; a pressure difference generation mechanism 4 that generates a pressure difference between the pressure in the pressure chamber 12 on one side of the spool 5 in the axial direction and the pressure chamber 13 on the other side of the spool 5 in the axial direction; a feedback spring 6 connecting the pressure difference generation mechanism 4 and the spool 5; and tanks 18 and 19 connected to each pressure chamber 12 and 13 via vibration damping passages 7 and 8. Furthermore, the inner surfaces of the vibration damping passages 7 and 8 include a first planar portion 55 and a second planar portion 56 substantially parallel to the first planar portion 55, with the distance between the first planar portion 55 and the second planar portion 56 being 100 μm or less.

Figure 10 is a schematic cross-sectional view corresponding to Figure 7 of the gas pressure servo valve 601 of the reference example. The gas pressure servo valve 601 differs from the above embodiment in that it uses an orifice 607 instead of a vibration-damping passage. The gas pressure servo valve 601 of the reference example also suppresses gas vibration with the orifice 607, making it easier to realize a high-performance gas pressure servo valve 601.

Against this background, the inventors have confirmed that vibrations can be significantly attenuated when the gas passes between the first planar section 55 and the second planar section 56, which are positioned at a distance of 100 μm or less and are substantially parallel, compared to the case where the gas passes through the orifice 607, which has a vibration damping effect, and reaches the tank 609. In one experimental example, it was confirmed that vibrations could be significantly attenuated to less than 1/5 per unit time compared to the case using the orifice 607. Furthermore, in one experimental example, it was confirmed that the time required to dampen vibrations could also be reduced to less than 1/5 of the time required when using the orifice 607. Therefore, according to this disclosure, a gas pressure servo valve 1 that can easily dampen vibrations in a short time can be realized.

Furthermore, the distance between the first planar portion 55 and the second planar portion 56 may be 50 μm or less.

This configuration allows for effective damping of minute vibrations, particularly in a small gas pressure servo valve 1 that fits in the palm of your hand, enabling the realization of a compact, user-friendly, and high-performance gas pressure servo valve 1.

Furthermore, the first planar portion 55 may be included in the first side wall portion 41 having a communication hole 43 that communicates with both the pressure chambers 12, 13 and the vibration damping passages 7, 8, and the second planar portion 56 may be included in the disk (flat plate member) 45. The gas pressure servo valve 1 may also further include a plurality of annular shims 48 sandwiched between the first side wall portion 41 and the disk 45 and arranged at intervals from each other, and fastening means 46 having a shaft portion 46a that penetrates the through-holes 48a of each shim 48 and fastening the disk 45 to the first side wall portion 41.

With this configuration, the distance between the first flat portion 55 and the second flat portion 56 can be easily and precisely adjusted simply by adjusting the thickness of the shim 48. Therefore, a gas pressure servo valve 1 with the desired damping characteristics can be manufactured simply and inexpensively.

Furthermore, the first planar portion 55 may be included in the first side wall portion 41 having a communication hole 43 that communicates with both the pressure chambers 12, 13 and the vibration damping channels 7, 8, and the second planar portion 56 may be included in the disk 45. Also, the vibration damping channels 7, 8 may have a plurality of vibration damping channel portions 7a extending substantially in the radial direction of the communication hole 43.

This configuration allows the tanks 18 and 19 to be installed outside the sleeve 11, thereby increasing their capacity and enhancing the vibration damping effect. Furthermore, since the vibration damping channels 7 and 8 have multiple vibration damping channel sections 7a, the vibration damping effect can be further enhanced. Therefore, the synergistic effect of these factors makes it easier to achieve superior vibration damping performance.

Furthermore, the disk 45 may have a disc shape, and its center may be directly opposite the approximate center of the communication hole 43 in the thickness direction of the disk 45.

This configuration makes it easy to form multiple vibration-damping channel sections 7a of approximately the same length. Therefore, it is easier to reduce noise and achieve high vibration damping performance.

Furthermore, tanks 18 and 19 may have an annular opening 18b.

According to this configuration, when the vibration-damping channels 7 and 8 have multiple vibration-damping channel sections 51a extending radially in substantially different directions, the gas from the multiple vibration-damping channel sections 51a can be easily flowed into the tanks 18 and 19.

This disclosure is not limited to the embodiments and their modifications described above, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

For example, in the above embodiment, a case was described in which vibration damping channels 7 and 8 are provided between two planar portions 55 and 56 by sandwiching a shim 48 between the two planar portions 55 and 56. However, one of the surfaces of the side wall portion facing the flat plate member and the surface of the flat plate member facing the side wall portion may have multiple grooves extending in the radial direction, and the other of the surfaces of the side wall portion facing the flat plate member and the surface of the flat plate member facing the side wall portion may define multiple vibration damping channel portions by closing the openings in the depth direction of the multiple grooves.

For more details, for example, instead of the disc-shaped disk 45, a modified disk 145 with a substantially disc-shaped form, as shown in Figure 11 with the surface 145a facing the first side wall portion 41, may be used. The surface 145a of the disk 145 is planar. The disk 145 has a disc-shaped recess 146 in the center of a circular shape in a plan view, facing the communication hole 43 on the surface 145a. The disk 145 also has a plurality of grooves 147 extending in the radial direction. The depth of the plurality of grooves 147 is the same. The bottom surface of each groove 147 is a plane perpendicular to the X direction (not shown in Figure 11). Each groove 147 communicates with the recess 146.

The depth of each groove 147 is 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less. The disk 145 has fastening means insertion holes 135 through which fastening means for fixing the disk 145 to the first side wall portion 41 are inserted. By fixing the disk 145 to the first side wall portion 41 using fastening means (not shown), the depth-direction openings of each groove 147 are completely sealed on the disk 145 side of the first side wall portion 41. This fixing allows for the formation of multiple vibration-damping flow channels 107 at the locations of the multiple grooves 147.

According to this configuration, by simply forming multiple shallow grooves 147 with a depth of 100 μm or less on either the surface of the first side wall portion 41 facing the disk 145 or the surface of the disk 145 facing the first side wall portion 41, a vibration-damping channel with high vibration damping performance can be easily and inexpensively formed.

Furthermore, as shown in Figure 11, the width of each vibration damping channel section 107 may be approximately constant.

According to this configuration, the vibration damping performance when the gas flows from the pressure chambers 12 and 13 to the tanks 18 and 19 in the direction indicated by arrow α can be made approximately the same as the vibration damping performance when the gas flows from the tanks 18 and 19 to the pressure chambers 12 and 13 in the direction indicated by arrow β. Therefore, depending on the specifications, the vibration damping performance can be increased.

Furthermore, as shown in Figure 12, which corresponds to Figure 11 in the disk 245 of another modified example, the width of each vibration damping channel 207 may increase towards the radially outward side.

According to this configuration, when the gas flows from the pressure chambers 12 and 13 to the tanks 18 and 19 in the direction indicated by arrow γ, the gas flow velocity can be reduced, thereby reducing noise.

Furthermore, if discs 145 and 245 are used as the flat plate members, the tanks 18 and 19 will have multiple openings arranged circumferentially on the cylindrical surface. However, even in this case, as with the case where disc 45 is used, gas from the multiple radially extending vibration damping flow channels 107 and 207 can be easily flowed into the tanks 18 and 19.

Furthermore, as shown in Figure 13, which corresponds to Figure 11 in another modified example of disk 345, the vibration damping channel may consist of only one vibration damping channel section 307 extending in the radial direction. Also, the flat plate member does not have to be disc-shaped; it may have any planar shape as long as it is flat. For example, the flat plate member may have a substantially rectangular or elliptical shape in plan view.

Furthermore, the case where the gas pressure servo valve 1 is a nozzle flapper type servo valve, and the pressure difference generation mechanism 4 has an armature 20, a flapper 21, a first coil 22, a second coil 23, a first back pressure passage 15, a second back pressure passage 16, an upper magnetic pole 25 with a U-shaped cross-section, and a lower magnetic pole 26 with a U-shaped cross-section, has been described. However, the gas pressure servo valve does not have to be a nozzle flapper type servo valve, and the pressure difference generation mechanism does not have to have a flapper.

More specifically, the gas pressure servo valve may be an injection-type servo valve, and the pressure difference generation mechanism may have a jet pipe. Figure 14 is a schematic axial cross-sectional view of another modified gas pressure servo valve 401. In Figure 14, the gas pressure servo valve 401 has vibration damping structures 406 and 407. The vibration damping structures 406 and 407 are vibration damping structures having vibration damping passages and tanks similar to the vibration damping structures described using Figures 7 and 8. Also, the illustration of the feedback spring is omitted in Figure 14. Referring to Figure 14, in the gas pressure servo valve 401, when the jet pipe 431 is tilted towards either control port 413 or 414 by a drive device such as a torque motor, more gas being injected from the injection port 431a flows into the tilted control port 413 or 414, thereby disrupting the balanced pressure balance of the pressure chambers 421 and 422, and causing the spool 405 to be displaced to the low-pressure side. The pressure difference generation mechanism 404 of the gas pressure servo valve 401 comprises a drive device such as a torque motor and a jet pipe 431. It goes without saying that in the gas pressure servo valve 401, the jet pipe 431 and the spool 405 are connected by a feedback spring (not shown).

Furthermore, the case in which the gas pressure servo valve 1 is equipped with tanks 18 and 19 outside the sleeve 11 has been described. However, the gas pressure servo valve may also be equipped with tanks inside the spool. Figure 15 is a schematic cross-sectional view of the area around one end in the X direction of the spool 505 of another modified gas pressure servo valve 501. The gas pressure servo valve 501 is a nozzle flapper type servo valve. The gas pressure servo valve 501 has the same vibration damping structure at both ends in the X direction of the spool 505. As shown in Figure 15, the spool 505 has the same tank 518 inside both ends in the X direction. The tank 518 communicates with the vibration damping passage 550 via a communication hole 532.

The pressure chamber 512 is a disc-shaped chamber, and its inner diameter is larger than the inner diameter of the sleeve 511. The pressure chamber 512 communicates with a nozzle (not shown) via a back pressure passage 515. The pressure chamber 512 is located outward in the X direction from the sleeve 511. The X-direction end of the spool 505 is located within the pressure chamber 512, and this X-direction end of the spool 505 is a large-diameter portion 571 with an outer diameter larger than the inner diameter of the sleeve 511. The large-diameter portion 571 has a larger outer diameter than the small-diameter portion 570 located within the sleeve 511 of the spool 505.

The vibration damping channel 550 is provided in the large-diameter section 571. The communication hole 532 extends in the X direction along the central axis of the large-diameter section 571. The vibration damping channel 550 has, for example, multiple vibration damping channel sections 550a, and these multiple vibration damping channel sections 550a extend in the radial direction of the large-diameter section 571. The multiple vibration damping channel sections 550a are formed, for example, by the structure described using Figure 11 (in Figure 15, fastening means such as bolts are not shown). As shown in the modified example in Figure 15, by making the inner diameter of the pressure chamber 512 larger than the inner diameter of the sleeve 511 and providing the large-diameter section 571 at the X-direction end of the spool 505, the length of the vibration damping channel 550 can be increased, thereby improving the vibration damping performance of the vibration damping channel 550.

In this configuration, the tank 518 is composed of an internal chamber located inside the spool 505, and the spool 505 has a communication hole 532 that connects the internal chamber to the vibration-damping flow path 550. Therefore, it is easy to realize a compact gas pressure servo valve 501 with high vibration-damping performance.

More specifically, the spool may comprise a spool body and a disc-shaped disk. The vibration damping channel may be formed by fixing the disc-shaped disk to the X-direction end face of the spool body, which is the axial member. More specifically, the tank may consist of an internal chamber located inside the spool body, and the spool body may have a communication hole connecting the tank and the vibration damping channel. The communication hole may have any cross-sectional shape, for example, a cylindrical hole. Furthermore, the center of the communication hole may face the center of the disk in the X-direction, and the disk may be fixed to the X-direction end face of the spool body with fastening means, using the same method as described above, with an annular shim sandwiched between them.

Alternatively, one or more radially extending grooves may be provided on either the X-direction end face of the spool body or the end face side of the disc, using the same method as described above. The disc may also be fixed to the X-direction end face of the spool body by fastening means while the X-direction end face of the spool body and the disc surface are in close contact.

In this modified example, the first planar portion is included in a disk fixed to the axial end face of the spool body, and the second planar portion is also included in the axial end face of the spool body. Furthermore, the opening of the communication hole is obscured from external view by the disk. This configuration allows for the realization of a compact gas pressure servo valve with high vibration damping performance. In the example shown in Figure 15, the X-direction end of the spool body had a larger outer diameter than the portion of the spool body positioned within the sleeve 511. However, in a configuration where a tank is provided in the spool body, the outer diameter of the X-direction end of the spool body may be approximately equal to the inner diameter of the sleeve.

1,401,501 Gas pressure servo valve, 2 Cover, 3 Lower housing, 4,404 Pressure difference generation mechanism, 5,405,505 Spool, 6 Feedback spring, 7 First vibration damping passage, 7a Vibration damping passage section, 8 Second vibration damping passage, 9 First nozzle, 10 Second nozzle, 11,511 Sleeve, 12 First pressure chamber, 13 Second pressure chamber, 15 First back pressure passage, 16 Second back pressure passage, 18 First tank, 19 Second tank, 20 Armature, 21 Flapper, 22 First coil, 23 Second coil, 25 Upper magnetic pole, 26 Lower magnetic pole, 28 Drive circuit, 30 First fixed throttle, 31 Second fixed throttle, 34 First land, 35 Second land, 36 37 Third land, 39 Fourth land, 39 Stem, 40 Side wall, 41 First side wall portion, 41a Outer surface of the first side wall portion, 42 Second side wall portion, 42a Recess of the second side wall portion, 43, 532 Communication hole, 45, 145, 245, 345 Disk, 45a Plane, 46 Fastening means, 46a Shaft portion, 48 Shim, 48a Through hole, 51a, 107, 207, 307, 550a Vibration damping flow path portion, 55 First planar portion, 56 Second planar portion, 84 Drive circuit, 145a Surface of the disk on the side of the first side wall portion, 147 Groove, 406 Vibration damping structure, 413, 414 Control port, 421 Pressure chamber, 431 Jet pipe, 431a Injection nozzle, 512 Pressure chamber, 515 Back pressure passage, 518 Tank, 550 Vibration damping passage, 570 Small diameter section, 571 Large diameter section, CY1 First output port, CY2 Second output port, Ex Exhaust port, PS1 First gas supply port, PS2 Second gas supply port.

Claims (9)

A sleeve having two gas supply ports, an exhaust port, and two output ports,
A spool that can slide within the sleeve,
The spool is provided with pressure chambers located on both sides of its axial direction,
A pressure difference generation mechanism that generates a pressure difference between the pressure in the pressure chamber on one side of the spool in the axial direction and the pressure in the pressure chamber on the other side of the spool in the axial direction,
A feedback spring connecting the pressure difference generation mechanism and the spool,
Each of the aforementioned pressure chambers is connected to a tank via a vibration-damping channel,
The inner surface of the vibration damping channel includes a first planar portion and a second planar portion substantially parallel to the first planar portion.
The distance between the first planar portion and the second planar portion is 100 μm or less.
The tank has only an opening connected to the vibration damping channel,
A gas pressure servo valve that allows both the flow of gas between the first and second planar sections, which are separated by a distance of 100 μm or less, from the pressure chamber side to the tank side, and the flow of gas between the first and second planar sections, which are separated by a distance of 100 μm or less, from the tank side to the pressure chamber side . The first planar portion is included in a side wall portion having a communication hole that communicates with both the pressure chamber and the vibration damping channel, and the second planar portion is included in a flat plate member,
A plurality of annular shims are sandwiched between the side wall portion and the flat plate member and are arranged at intervals from each other,
The gas pressure servo valve according to claim 1, further comprising a fastening means having a shaft portion that penetrates the through holes of each of the shims and fastening the flat plate member to the side wall portion. The first planar portion is included in a side wall portion having a communication hole that communicates with both the pressure chamber and the vibration damping channel, and the second planar portion is included in a flat plate member,
The gas pressure servo valve according to claim 1, wherein the vibration damping passage has a plurality of vibration damping passage portions extending substantially in the radial direction of the communication hole. The gas pressure servo valve according to claim 3, wherein the width of each vibration damping flow path is substantially constant. The gas pressure servo valve according to claim 3, wherein the width of each vibration damping flow path increases as it moves radially outward. One of the surfaces of the side wall portion facing the flat plate member and the surface of the flat plate member facing the side wall portion has a plurality of grooves extending in the radial direction.
The gas pressure servo valve according to any one of claims 3 to 5, wherein the plurality of vibration damping flow channels are defined by the other of the side wall side of the flat plate member and the side wall side of the flat plate member closing the opening in the depth direction of the plurality of grooves. The aforementioned flat plate member has a disc shape,
The gas pressure servo valve according to any one of claims 2 to 6, wherein the center of the flat plate member faces the approximate center of the communication hole in the thickness direction of the flat plate member. The gas pressure servo valve according to claim 7, wherein the tank has an annular opening or a plurality of openings arranged circumferentially at intervals on a cylindrical surface. The tank is composed of an internal chamber provided inside the spool,
The gas pressure servo valve according to claim 1, wherein the spool has a communication hole that connects the internal chamber and the vibration damping passage.