Servo cylinder

Abstract

To provide a servo cylinder which enables simplification of a control system and easily achieves compactification.SOLUTION: A servo cylinder 1 includes: a housing 3 having a slider slide chamber 18 extending in an X direction; a cylinder 5 disposed in the cylinder slide chamber 18 so as to be slidable in the X direction relative to the cylinder slide chamber 18 and having an annular groove 5c provided on the outer peripheral surface, a large diameter part 5d provided at one side in the X direction of the annular groove 5c, and a small diameter part 5e which is connected to one side in the X direction of the large diameter part 5d through a step part 19 and has a diameter smaller than that of the large diameter part 5d; a first atmospheric pressure chamber 12 in which a gas for providing force acting to the other side in the X direction to the step part 19 is contained; a second atmospheric pressure chamber 13 in which a gas for providing force acting to the one side in the X direction to the end surface at the other side in the X direction of the cylinder 5 is contained; an atmospheric pressure difference generation mechanism 4 which generates an atmospheric pressure difference between the atmospheric pressure in the first atmospheric pressure chamber 12 and the atmospheric pressure in the second atmospheric pressure chamber 13; and a feedback spring 6 having one end fixed to the atmospheric pressure difference generation mechanism 4 and the other end housed in the annular groove 5c.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a servo cylinder. [Background technology]

[0002] A conventional servo cylinder system is described in Patent Document 1. This servo cylinder system includes an air cylinder that moves a controlled object in a linear direction according to the pressure in a pressure chamber, a servo valve that supplies and exhausts compressed air to and from the pressure chamber, a position detection means that detects the position of the controlled object, and a controller that inputs the detected position detected by the position detection means, determines the deviation from a target position, and outputs a command voltage to the servo valve based on the deviation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-141884 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above servo cylinder system, since the air cylinder and the servo valve are configured separately from each other, the control system is likely to become complicated and the system is likely to become large. Therefore, an object of the present disclosure is to provide a servo cylinder that can simplify the control system and easily realize compactness. [Means for solving the problem]

[0005] In order to solve the above problem, the servo cylinder according to the present disclosure includes a housing having a cylinder sliding chamber extending in one direction, a cylinder arranged within the cylinder sliding chamber to be slidable in the one direction relative to the cylinder sliding chamber, the cylinder including a recess provided on an outer peripheral surface, a large diameter portion provided on a first side of the recess in the one direction, and a small diameter portion connected to the first side of the large diameter portion in the one direction via a step portion and having a smaller diameter than the large diameter portion, a first pressure chamber containing a gas that imparts a force on a second side in the one direction to the step portion, a second pressure chamber containing a gas that imparts the force on the first side in the one direction to an end face of the cylinder on the second side in the one direction, a pressure difference generating mechanism that generates a pressure difference between the pressure in the first pressure chamber and the pressure in the second pressure chamber, and a feedback spring having one end fixed to the pressure difference generating mechanism and the other end contained in the recess.

[0006] According to the present disclosure, the air pressure difference between the first and second air pressure chambers that apply force to both end faces of the cylinder is directly controlled by the air pressure difference generating mechanism, and the position of the cylinder is controlled based on the air pressure difference and the restoring force of the feedback spring. Therefore, compared to a case where the air cylinder and the servo valve are configured separately from each other, the control system can be simplified and compactness can be easily achieved.

[0007] The air pressure difference generating mechanism may include an armature extending linearly, a flapper formed integrally with the armature and constituting a T-shaped member together with the armature, a first coil wound on one side of the center of the armature, a second coil wound on the other side of the center of the armature, a first nozzle and a second nozzle extending in a direction substantially perpendicular to the extension direction of the flapper, the distances from the flapper being substantially the same and facing each other in the orthogonal direction via the flapper when no current flows through the first coil and the second coil, a first back pressure path communicating between the first nozzle and the first air pressure chamber, and a second back pressure path communicating between the second nozzle and the second air pressure chamber.

[0008] According to this configuration, the servo cylinder can be configured with a simple structure, and compactness can be effectively achieved.

[0009] The air pressure difference generating mechanism includes an armature extending linearly, a flapper that is provided integrally with the armature and that constitutes a T-shaped member together with the armature, a first coil that is wound around one side of the center of the armature, a second coil that is wound around the other side of the center of the armature, and a first nozzle and a second nozzle that extend in a direction substantially perpendicular to the direction in which the flapper extends, have substantially the same distance from the flapper, and face the flapper in the perpendicular direction when no current flows through the first coil and the second coil. and a second nozzle, and a flow rate booster valve, the flow rate booster valve including a sleeve having two gas supply ports, an exhaust port, and two output ports, a spool slidable within the sleeve, a third air pressure chamber provided outside a first axial side of the spool, a fourth air pressure chamber provided outside a second axial side of the spool, and a force applying portion that applies a force in the axial direction to the spool, the spool including three large diameter lands spaced apart in the axial direction, and a pressure chamber between adjacent lands having an outer diameter smaller than the lands. the force application unit applies to the spool a force for positioning the spool at a position where the output port does not communicate with both the gas supply port and the exhaust port, and further includes a first back pressure path that communicates one of the first nozzle and the second nozzle with one of the third pressure chamber and the fourth pressure chamber, a second back pressure path that communicates the other of the first nozzle and the second nozzle with the other of the third pressure chamber and the fourth pressure chamber, and a second back pressure path that communicates one of the two output ports with a second back pressure path that communicates the other of the first nozzle and the second nozzle with a second back pressure path that communicates the other of the first pressure chamber and the second pressure chamber. a third back pressure passage that communicates with one of the first and second pressure chambers, and a fourth back pressure passage that communicates the other of the two output ports with the other of the first and second pressure chambers, and in a neutral position of the spool where no current flows through the first coil and the second coil, the output port does not communicate with both the gas supply port and the exhaust port, while when the spool moves in the axial direction from the neutral position, one of the two output ports communicates with the exhaust port via one of the two stems, and the other of the two output ports communicates withThe other of the two stems may be in communication with one of the two gas supply ports.

[0010] According to this configuration, the flow rate per unit time of the gas flowing into the first and second pressure chambers can be increased when the cylinder is moved by the operation of the flow booster valve, thereby increasing the moving speed of the cylinder and improving the responsiveness of the servo cylinder.

[0011] The feedback spring may have an easily displaceable portion at a location other than both ends.

[0012] According to this configuration, the stroke of the feedback spring can be increased, and the control range in the position control of the cylinder can be widened. Effect of the Invention

[0013] According to the servo cylinder of the present disclosure, the control system can be simplified and compactness can be easily achieved. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a plan view of the servo cylinder of the first embodiment as viewed from above. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1, the cross-sectional view including the central axis of the flapper in the neutral position and the Y direction. [Diagram 3] 3 is a cross-sectional view taken along line BB in FIG. 2. [Figure 4] 10A to 10C are diagrams illustrating the operation of the air pressure difference generating mechanism. [Diagram 5] 4(a) is a cross-sectional view corresponding to FIG. 3 when the armature is tilted in the direction indicated by the arrow B in FIG. 4(a). [Figure 6] FIG. 11 is a plan view of a servo cylinder according to a second embodiment, as viewed from above. [Figure 7] 1, which is a cross-sectional view taken along line CC in FIG. 1 and includes the central axis of the flapper 21 at the neutral position in the cylinder body and the Y direction. [Figure 8] FIG. 13 is a cross-sectional view for explaining the structure of a servo cylinder according to a second embodiment, showing the servo cylinder before operation. [Figure 9] 9 is a cross-sectional view corresponding to FIG. 8 during operation of the servo cylinder of the second embodiment. [Figure 10] 9 is a cross-sectional view corresponding to FIG. 8 when positioning of the servo cylinder of the second embodiment is completed. [Figure 11] 13A and 13B are diagrams illustrating a feedback spring of a first modified example. [Figure 12] 13A and 13B are diagrams illustrating a feedback spring of a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. In addition, when multiple embodiments or modified examples are included below, it is assumed from the beginning that new embodiments will be constructed by appropriately combining the characteristic parts of those. In addition, in the following examples, the same components are given the same symbols in the drawings, and duplicated explanations are omitted. In addition, multiple drawings include schematic diagrams, and the dimensional ratios of length, width, height, etc. of each member between different drawings do not necessarily match. In addition, among the components described below, components that are not described in the independent claims showing the highest concept are optional components and are not essential components.

[0016] The gas used in the servo cylinder 1, 101 may be any gas, but the gas may be air or an inert gas, such as argon or nitrogen. In the following description and drawings, the X direction is the axial direction of the cylinder 5, the Z direction is the direction in which the flapper 21 extends in a neutral position, which will be described below, and is perpendicular to the X direction. The Y direction is the direction perpendicular to both the X direction and the Z direction.

[0017] In the following examples, the rooms and passages are shown in shades of gray, and are expressed in a grayscale. The darker the gray, the more high-pressure gas is present in the room or passage. In the following examples, the passages (e.g., the first to third back pressure passages) are shown as lines. The thickness of the line represents the magnitude of the air pressure of the gas present in the passage.

[0018] (First embodiment) Fig. 1 is a plan view of the servo cylinder 1 of the first embodiment as viewed from above. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1, which includes the central axis of the flapper 21 in the neutral position and the Y direction. Fig. 3 is a cross-sectional view taken along line BB in Fig. 2.

[0019] 1 and 2, the servo cylinder 1 has a generally rectangular shape in plan and side views. As shown in Fig. 3, the servo cylinder 1 includes a cover 2, a housing 3, a nozzle flapper type air pressure difference generating mechanism 4, a cylinder 5, a feedback spring 6, a first air pressure chamber 12, and a second air pressure chamber 13.

[0020] The air pressure difference generating mechanism 4 includes a first nozzle 9, a second nozzle 10, 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 having a U-shaped cross section, and a lower magnetic pole 26 having 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 is elongated and extends in the Z direction in a neutral position. The upper magnetic pole 25 and the lower magnetic pole 26 are disposed opposite each other in the Z direction with a gap therebetween, with their recesses facing each other in the Z direction. Both ends 20a, 20b of the armature 20 are disposed between the magnetic gap formed by the pole portion (end) 25a of the upper magnetic pole 25 and the pole portion (end) 26a of the lower magnetic pole 26.

[0021] 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. A total of four lead wires (not shown) drawn from both ends of the first coil 22 and both ends of the second coil 23 are drawn outside the servo cylinder 1 and electrically connected to a drive circuit included in a control device (not shown). The air pressure difference generating mechanism 4 is driven by the drive circuit controlled by the control device.

[0022] The flapper 21 is disposed across the internal space of the cover 2 and the internal space of the housing 3, and is a hollow tube extending in the Z direction in a neutral position. The feedback spring 6 has a portion disposed inside the hollow tube of the flapper 21, and is an elastic shaft extending in the Z direction in a neutral position. The upper end of the feedback spring 6 is fixed to the inner circumferential surface of the hollow flapper 21.

[0023] The housing 3 has a cylinder sliding chamber 18 of a substantially cylindrical shape extending in the X direction. As shown in FIG. 2, the cylinder sliding chamber 18 is disposed eccentrically in the Y direction, and the central axis of the cylinder sliding chamber 18 is located on one side in the Y direction with respect to the Y direction position where the feedback spring 6 is present. As shown in FIG. 2 and FIG. 3, the cylinder 5 includes two cylindrical medium diameter parts 5a and a cylindrical small diameter part 5b disposed between the two medium diameter parts 5a and having an outer diameter smaller than that of the medium diameter parts 5a, and has an annular groove 5c whose bottom surface is formed by the cylindrical outer circumferential surface of the small diameter part 5b. The annular groove 5c is an example of a recess in the cylinder 5 in which the tip part of the feedback spring 6 is accommodated.

[0024] 2, the tip of the feedback spring 6 is accommodated in the annular groove 5c, so that the lower end of the feedback spring 6 is connected to the center of the cylinder 5. By accommodating the tip of the feedback spring 6 in the annular groove 5c, when the cylinder 5 rotates relative to the housing 3, the tip of the feedback spring 6 can rotate relative to the cylinder 5. Therefore, even if the cylinder 5 rotates relative to the housing 3, almost no circumferential force acts on the tip of the feedback spring 6, so that damage to the feedback spring 6 can be suppressed.

[0025] Next, the operation of the air pressure difference generating mechanism 4 will be described with reference to FIG. 4. As shown in FIG. 4(a), for example, the two poles 25a of the upper magnetic pole 25 are polarized to N poles, and the two poles 26b of the lower magnetic pole 26 are polarized to the opposite S poles. Here, by controlling the direction of the current flowing through the two coils 22, 23, it is possible to generate opposite magnetic poles at the one end 20a and the other end 20b of the armature 20 according to the right-handed screw rule. By controlling the direction of the current flowing through the two coils 22, 23, it is possible to apply a force in the direction indicated by the arrow A or the direction indicated by the arrow B to the one end 20a and the other end 20b based on the attractive and repulsive forces acting between the upper magnetic pole 25 and the lower magnetic pole 26, as shown in FIG. 4(b).

[0026] Therefore, as shown in FIG. 4(c), the armature 20 can be rotated in the clockwise direction indicated by the arrow C or the counterclockwise direction indicated by the arrow D with the fixed center S as a fulcrum, and the flapper 21 can be rotated in the clockwise direction indicated by the arrow C or the counterclockwise direction indicated by the arrow D with the fixed center S as a fulcrum from a neutral position extending in the Z direction perpendicular to the X direction. As a result, the flapper 21 and the feedback spring 6 can be tilted from the neutral position to one side or the other side in the X direction. In addition, in a state where no current flows through both of the two coils 22 and 23, the armature 20 is not magnetized, no force acts between the armature 20 and the upper magnetic pole 25 and the lower magnetic pole 26, and the armature 20 extends parallel to the X direction. The position of the armature 20 in a state where no current flows through both of the two coils 22 and 23 is the neutral position.

[0027] 3 again, the first nozzle 9 and the second nozzle 10 extend in the X direction. The first nozzle 9 and the second nozzle 10 are arranged 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 a nozzle opening at the tip along the X direction to the flapper 21. A first fixed throttle (orifice) 30 is provided between the gas supply source and the first nozzle 9, and a second fixed throttle (orifice) 31 is provided between the gas supply source and the second nozzle 10. The first nozzle 9 and the second nozzle 10 are supplied with gas that has passed through a filter 47 from a gas supply source having a predetermined supply gas pressure Ps and has been throttled by the first fixed throttle 30 and the second fixed throttle 31. A first back pressure passage 15 branches off between the first fixed throttle 30 and the first nozzle 9, and a second back pressure passage 16 branches off between the second fixed throttle 31 and the second nozzle 10.

[0028] As described above, the housing 3 has the cylinder sliding chamber 18 having a substantially cylindrical shape extending in the X direction. The cylindrical inner wall surface of the cylinder sliding chamber 18 is precisely machined to slidably support the cylinder 5. In this embodiment, the case where the cross-sectional shape of the inner wall surface of the cylinder sliding chamber 18 is circular will be described, but the cross-sectional shape of the inner wall surface of the cylinder sliding chamber 18 may be rectangular or the like. The first air pressure chamber 12 is provided on one side of the housing 3 in the X direction, and the second air pressure chamber 13 is provided on the other side of the housing 3 in the X direction.

[0029] Specifically, the cylinder 5 has a cylindrical large diameter portion 5d that is connected to each of the medium diameter portions 5a via a step portion on the outside in the X direction and has an outer diameter larger than that of the medium diameter portion 5a. The cylinder 5 also has a cylindrical small diameter portion 5e that is connected to the large diameter portion 5d on one side in the X direction via an annular step portion 19 and has an outer diameter smaller than that of the large diameter portion 5d. The cylinder sliding chamber 18 has one side in the X direction closed by a first closing portion 34 of the housing 3, and the first closing portion 34 has a cylindrical hole 35 that penetrates the first closing portion 34 in the X direction and has an inner diameter that is approximately equal to the outer diameter of the small diameter portion 5e. A part of the small diameter portion 5e is disposed in the cylindrical hole 35, and the tip portion of the small diameter portion 5e protrudes from the first closing portion 34 to one side in the X direction.

[0030] The other side in the X direction of the cylinder sliding chamber 18 is closed by the second closing portion 36 of the housing 3. The first air pressure chamber 12 is an annular chamber defined by the end face on the other side in the X direction of the first closing portion 34, the cylindrical outer peripheral surface of the small diameter portion 5e, the annular step portion 19 of the cylinder 5, and the cylindrical inner peripheral surface of the cylinder sliding chamber 18. The second air pressure chamber 13 is a chamber defined by the end face on the other side in the X direction of the cylinder 5, the cylindrical inner peripheral surface of the cylinder sliding chamber 18, and the end face on one side in the X direction of the second closing portion 36. The first back pressure passage 15 communicates with the first air pressure chamber 12, and the second back pressure passage 16 communicates with the second air pressure chamber 13.

[0031] In the above configuration, the servo cylinder 1 operates as follows. First, in the initial neutral position shown in Fig. 3, no drive current is supplied from the drive circuit of the control device to the coils 22, 23, and the armature 20 is not magnetized. The flapper 21 is located between the first nozzle 9 and the second nozzle 10. Therefore, even if gas at the supply gas 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 air pressures of the first air pressure chamber 12 and the second air pressure chamber 13 are the same. Therefore, the cylinder 5 is located in a neutral position where the feedback spring 6 extends parallel to the Z direction.

[0032] On the other hand, suppose that a current is passed through the coils 22 and 23 in a direction that tilts the armature 20 in the direction indicated by the arrow B in FIG. 4(a). Then, the armature 20 rotates in the direction indicated by the arrow B, and the flapper 21 integrated with the armature 20 rotates around the center of rotation accordingly, and the flapper 21 moves closer to the first nozzle 9 than in the neutral position and farther from the second nozzle 10 than in the neutral position. Then, the back pressure of the first nozzle 9 and the back pressure of the second nozzle 10 change accordingly, and in the example of FIG. 5, (the back pressure of the first nozzle 9)>(the back pressure of the second nozzle 10). The back pressure of the first nozzle 9 is led to the first air pressure chamber 12 by the first back pressure path 15, and the back pressure of the second nozzle 10 is led to the second air pressure chamber 13 by the second back pressure path 16.

[0033] As a result, a pressure difference occurs between both ends of the cylinder 5 in the axial direction, so that the cylinder 5 moves in the axial direction, and in the example shown in FIG. 5, moves to the other side in the X direction (left side of the paper). As the cylinder 5 moves to the other side in the X direction, the lower end of the feedback spring 6 also moves to the other side in the X direction. As a result, the feedback spring 6 is bent to the other side in the X direction, and its elastic reaction force acts on one side in the X direction. In other words, the elastic reaction force of the feedback spring 6 is generated so as to return the cylinder 5 to one side in the X direction. When the torque that the armature 20 receives from the flapper 21 due to the distortion of the feedback spring 6 and the torque that the armature 20 receives from the upper magnetic pole 25 and the lower magnetic pole 26 are in a balanced state, the armature 20 stops in a state in which the armature 20 is inclined to one side in the X direction and the feedback spring 6 is inclined to the other side in the X direction as it moves downward in the Z direction, and the cylinder 5 is in a balanced state, and the cylinder 5 stops.

[0034] When the armature 20 rotates in the direction indicated by the arrow A in Fig. 4(B), the operation is the same as that described in Fig. 5 except that the cylinder 5 moves to one side (right side) in the X direction instead of the other side (left side) in the X direction. The pressure difference between the first air pressure chamber 12 and the second air pressure chamber 13 corresponds one-to-one to the direction and magnitude of the current flowing through the coils 22 and 23. Therefore, by controlling the direction and magnitude of the current flowing through the coils 22 and 23 with high precision, the X direction dimension of the small diameter portion 5e protruding in the X direction from the first closing portion 34 in the cylinder 5 can be adjusted with high precision. Therefore, a high precision cylinder mechanism can be constructed.

[0035] As described above, the servo cylinder 1 includes a housing 3 having a cylinder sliding chamber 18 extending in one direction (X direction), a cylinder 5 arranged in the cylinder sliding chamber 18 so as to be slidable in one direction relative to the cylinder sliding chamber 18, the cylinder 5 including a recess (annular groove 5c) provided on the outer circumferential surface, a large diameter portion 5d provided on a first side (one side) in one direction of the annular groove 5c, and a small diameter portion 5e connected to the first side in one direction of the large diameter portion 5d via a step portion 19 and having a smaller diameter than the large diameter portion 5d, a first pressure chamber 12 containing a gas that applies a force of a second side (other side) in one direction to the step portion 19, a second pressure chamber 13 containing a gas that applies a force of the first side in one direction to an end face of the cylinder 5 on the second side in one direction, an air pressure difference generating mechanism 4 that generates an air pressure difference between the air pressure in the first pressure chamber 12 and the air pressure in the second pressure chamber 13, and a feedback spring 6 having one end fixed to the air pressure difference generating mechanism 4 and the other end contained in the annular groove 5c.

[0036] According to the present disclosure, the air pressure difference between the first and second air pressure chambers 12, 13 that apply force to both end faces of the cylinder 5 is directly controlled by the air pressure difference generating mechanism 4, and the position of the cylinder 5 is controlled based on the air pressure difference and the restoring force of the feedback spring 6. Therefore, compared to the conventional example in which the air cylinder and the servo valve are configured separately from each other, the control system can be simplified and compactness can be easily achieved.

[0037] The air pressure difference generating mechanism 4 may also include an armature 20 extending linearly, a flapper 21 that is integral with the armature 20 and forms a T-shaped member together with the armature 20, a first coil 22 wound around one side of the center of the armature 20, a second coil 23 wound around the other side of the center of the armature 20, a first nozzle 9 and a second nozzle 10 that extend in a direction substantially perpendicular to the direction of extension of the flapper 21, have substantially the same distance from the flapper 21, and face each other in the perpendicular direction via the flapper 21 when no current flows through the first and second coils 22 and 23, a first back pressure path 15 that communicates the first nozzle 9 with the first air pressure chamber 12, and a second back pressure path 16 that communicates the second nozzle 10 with the second air pressure chamber 13. According to this configuration, the servo cylinder 1 can be configured with a simpler configuration, and compactness can be effectively achieved.

[0038] Second embodiment In order to increase the responsiveness of the cylinder 5, it is necessary to increase the flow rate per hour of the gas supplied to the first pressure chamber 12 and the second pressure chamber 13, and therefore it is necessary to increase the cross-sectional area of ​​the first back pressure passage 15 and the second back pressure passage 16. However, it may be difficult to increase the passage cross-sectional area of ​​the first back pressure passage 15 and the second back pressure passage 16 due to the structure of the housing 3, etc. In the second embodiment, a configuration that can increase the responsiveness of the cylinder 5 even in such a case will be described. In the second embodiment, the same reference numbers as in the first embodiment are used for the same configuration as in the first embodiment, and the description will be omitted. In addition, in the second embodiment, the description of the same action and effect as in the first embodiment will be omitted.

[0039] FIG. 6 is a plan view of the servo cylinder 101 of the second embodiment when viewed from above. FIG. 7 is a cross-sectional view taken along the line CC in FIG. 1, which is a cross-sectional view including the central axis of the flapper 21 at the neutral position of the cylinder body 110 and the Y direction. As shown in FIG. 6, the servo cylinder 101 includes the cylinder body 110 and a flow rate booster valve 150. The flow rate booster valve 150 is fixed to a side surface of the cylinder body 110 extending in the X direction. As shown in FIG. 2 and FIG. 7, the cross-sectional view including the central axis of the flapper 21 at the neutral position of the cylinder body 110 and the Y direction coincides with the cross-sectional view including the central axis of the flapper 21 at the neutral position of the servo cylinder 1 and the Y direction.

[0040] FIG. 8 is a cross-sectional view for explaining the structure of the servo cylinder 101. In FIG. 8, the cross-section of the cylinder body 110 corresponds to the cross-sectional view of line DD in FIG. 7. Also, the cross-section of the flow rate booster valve 150 is a cross-sectional view in the axial direction of the spool 105 provided in the flow rate booster valve 150. Also, in reality, the cylinder body 110 and the flow rate booster valve 150 are not separated from each other, but in FIG. 8 to FIG. 10, the flow rate booster valve 150 is drawn separated from the cylinder body 110 in order to easily explain the flow of gas during operation.

[0041] 8, the flow booster valve 150 includes a cylindrical sleeve 151 and a spool 105 fitted slidably in the X direction into an inner peripheral cylindrical surface of a spool sliding chamber 152 provided in the sleeve 151. The flow booster valve 150 also includes a third closing portion 157 disposed on one side of the sleeve 151 in the X direction and closing an opening on one side of the spool sliding chamber 152 in the X direction without any gap, and a fourth closing portion 158 disposed on the other side of the sleeve 151 in the X direction and closing an opening on one side of the spool sliding chamber 152 in the X direction without any gap. The flow booster valve 150 also includes first to fourth permanent magnets 161, 162, 163, and 164 as an example of a force applying portion.

[0042] The cylindrical inner wall surface of the spool sliding chamber 152 is precisely machined to slidably support the spool 105. In this embodiment, the cross section of the spool sliding chamber 152 is circular, but the cross section of the spool sliding chamber 152 may be rectangular or the like. The third air pressure chamber 112 is provided on one side of the spool 105 in the X direction within the third closing portion 157, and the fourth air pressure chamber 113 is provided on the other side of the spool 105 in the X direction within the fourth closing portion 158. The first back pressure passage 115 of the cylinder body 110 communicates with the third air pressure chamber 112, and the second back pressure passage 116 of the cylinder body 110 communicates with the fourth air pressure chamber 113.

[0043] The sleeve 151 has five annular ports that communicate with the spool sliding chamber 152 and are spaced apart from one another in the X direction. In detail, the sleeve 151 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. The first output port CY1 and the second output port CY2 are preferably arranged substantially symmetrically with respect to a plane that includes the central axis of the exhaust port Ex and the Y direction, and the first gas supply port Ps1 and the second gas supply port Ps2 are also preferably arranged substantially flush with the plane.

[0044] In this embodiment, the first output port CY1 is disposed between the first gas supply port Ps1 and the exhaust port Ex, and the second output port CY2 is disposed between the second gas supply port Ps2 and the exhaust port Ex. However, the first gas supply port Ps1 may be disposed between the first output port CY1 and the exhaust port Ex, and the second gas supply port Ps2 may be disposed between the second output port CY2 and the exhaust port Ex.

[0045] The servo cylinder 1 of the first embodiment and the cylinder body 110 are different in the positions where the first back pressure passages 15, 115 and the second back pressure passages 16, 116 are formed. In addition, the cylinder body 110 has a third back pressure passage 117 and a fourth back pressure passage 118 that the servo cylinder 1 does not have. Other than that, the configurations of the servo cylinder 1 and the cylinder body 110 are the same.

[0046] With respect to the cylinder body 110, a first back pressure passage 115 branches off between the first fixed throttle 30 and the first nozzle 9, and a second back pressure passage 116 branches off between the second fixed throttle 31 and the second nozzle 10. The first back pressure passage 115 communicates with the third pressure chamber 112, and the second back pressure passage 116 communicates with the fourth pressure chamber 113. The first output port CY1 and the second pressure chamber 13 of the cylinder body 110 communicate with each other via a third back pressure passage 117, and the second output port CY2 and the second pressure chamber 13 of the cylinder body 110 communicate with each other via a fourth back pressure passage 118. The passage cross-sectional areas of the first to fourth back pressure passages 115, 116, 117, 118 are larger than the passage cross-sectional areas of the first and second back pressure passages 15, 16 of the servo cylinder 1 of the first embodiment.

[0047] The external connection ports corresponding to the gas supply ports Ps1, Ps2 are connected to a gas supply source (not shown) and gas is supplied at a predetermined supply gas pressure Ps. Although not shown, a chamber 88 indicated as EX in the cylinder body 110 and housing a portion of the feedback spring 6 on the cylinder 5 side is connected to an exhaust port Ex. Gas used in the servo cylinders 1, 101 is exhausted from the external connection port corresponding to the exhaust port Ex. The exhausted gas is returned to a recovery tank or released directly to the atmosphere.

[0048] The spool 105 is a shaft having three lands 134, 135, and 136 having an outer diameter capable of sliding on the inner wall surface of the spool sliding chamber 152 of the sleeve 151, and two stems 138 and 139 having an outer diameter smaller than the lands 134, 135, and 136 and connecting the adjacent lands 134, 135, and 136. The spool 105 has a first land 134, a second land 135, and a third land 136 from one side in the axial direction. A first stem 138 constituting an annular recess is disposed between the first land 134 and the second land 135, and a second stem 139 constituting an annular recess is disposed between the second land 135 and the third land 136.

[0049] The first to fourth permanent magnets 161, 162, 163, and 164 are preferably configured as the same permanent magnet, for example, as a disk-shaped permanent magnet. Each of the permanent magnets 161, 162, 163, and 164 has a circular first end face included in the S pole and a circular second end face included in the N pole. Each of the permanent magnets 161, 162, 163, and 164 may have a configuration in which the first end face is included in the N pole and the second end face is included in the S pole.

[0050] The first permanent magnet 161 is fixed to the third closing portion 157 so that a first end face faces in the X direction to an end face on one axial side of the spool 105, and the second permanent magnet 161 is fixed to an end portion on one axial side of the spool 105 so that its first end face faces in the axial direction to the first end face of the first permanent magnet 161. The first permanent magnet 161 and the second permanent magnet face each other in the axial direction via the third air pressure chamber 112.

[0051] The third permanent magnet 163 is fixed to the fourth closing portion 158 so that a first end face faces the other axial end face of the spool 105 in the axial direction, and the fourth permanent magnet 164 is fixed to the other axial end face of the spool 105 so that its first end face faces the first end face of the third permanent magnet 163 in the axial direction. The third permanent magnet 163 and the fourth permanent magnet 164 face each other in the axial direction via the fourth air pressure chamber 113.

[0052] In the above configuration, in the initial state where no current is supplied to the first coil 22 and the second coil 23 of the air pressure difference generating mechanism 4, the flapper 21 is located midway between the first nozzle 9 and the second nozzle 10, as shown in Fig. 8. Even if gas at the supply gas pressure Ps is supplied from the gas supply source to the first nozzle 9 and the second nozzle 10, the back pressures of the first nozzle 9 and the second nozzle 10 are the same, and the air pressures of the third air pressure chamber 112 and the fourth air pressure chamber 113 are the same.

[0053] In this case, the first output port CY1 does not communicate with either the first gas supply port Ps1 or the exhaust port Ex, and the second output port CY2 does not communicate with either the second gas supply port Ps2 or the exhaust port Ex. Then, a gas (medium pressure gas) at an atmospheric pressure lower than the atmospheric pressure (high pressure) of the first and second gas supply ports Ps1, Ps2 and higher than the atmospheric pressure (low pressure) of the exhaust port Ex is supplied from the first output port CY1 to the second air pressure chamber 13 via the third back pressure passage 117, and a medium pressure gas is supplied from the second output port CY2 to the first air pressure chamber 12 via the fourth back pressure passage 118. As a result, the atmospheric pressures of the first air pressure chamber 12 and the second air pressure chamber 13 become the same, and the cylinder 5 stops at a position where the feedback spring 6 extends in the Z direction.

[0054] On the other hand, suppose that a current is passed through the coils 22 and 23 in a direction that tilts the armature 20 in the direction indicated by the arrow B in FIG. 4(a). Then, the armature 20 rotates in the direction indicated by the arrow B, and the flapper 21 integrated with the armature 20 rotates around the center of rotation, and the flapper 21 moves closer to the first nozzle 9 than in the neutral position and farther from the second nozzle 10 than in the neutral position. Then, as shown in FIG. 9, that is, a diagram corresponding to FIG. 8 during operation, the back pressure of the first nozzle 9 and the back pressure of the second nozzle 10 change, and the back pressure of the first nozzle 9 becomes greater than the back pressure of the second nozzle 10. The back pressure of the first nozzle 9 is led to the third air pressure chamber 112 by the first back pressure path 115, and the back pressure of the second nozzle 10 is led to the fourth air pressure chamber 113 by the second back pressure path 116.

[0055] As a result, the spool 105 moves to the other side in the X direction (left side in the X direction) based on this air pressure difference, and the first output port CY1 communicates with the exhaust port Ex filled with low-pressure gas via the first stem 138, and the second output port CY2 communicates with the second gas supply port Ps2 filled with high-pressure gas via the second stem 139. As a result, the pressure of the second air pressure chamber 13 communicating with the first output port CY1 via the third back pressure path 117 becomes smaller than the pressure of the first air pressure chamber 12 communicating with the second output port CY2 via the fourth back pressure path 118, and the cylinder 5 moves to the other side in the X direction (left side in the X direction) based on the air pressure difference between the first air pressure chamber 12 and the second air pressure chamber 13.

[0056] As the spool 105 moves to the other side in the X direction, the distance in the X direction between the third permanent magnet 163 and the fourth permanent magnet 164 becomes smaller, and the repulsive force acting between the third permanent magnet 163 and the fourth permanent magnet 164 increases accordingly, and the spool 105 receives a force on one side in the axial direction based on the repulsive force. The spool 105 receives a first force on the other side in the X direction based on the air pressure difference between the air pressure in the third air pressure chamber 112 and the air pressure in the fourth air pressure chamber 113, a second force on the other side in the X direction based on the repulsive force between the first permanent magnet 161 and the second permanent magnet 162, and a third force on one side in the X direction based on the repulsive force between the third permanent magnet 163 and the fourth permanent magnet 164. The spool 105 stops at an axial position where the sum of the first force and the second force is equal to the third force.

[0057] Since the passage cross-sectional areas of the first to fourth back pressure paths 115, 116, 117, 118 are larger than the passage cross-sectional areas of the first and second back pressure paths 15, 16 of the servo cylinder 1 of the first embodiment, gas with a larger flow rate per unit time flows into the first air pressure chamber 12 compared to the servo cylinder 1 of the first embodiment, and as a result, the cylinder 5 moves to the other side in the X direction (the left side in the X direction) at high speed, improving the responsiveness of the servo cylinder 101.

[0058] As the cylinder 5 moves to the other side in the X direction, the tip of the feedback spring 6 moves from the center position in the X direction to the other side in the X direction and becomes distorted. The cylinder 5 receives a fourth force on the other side in the X direction based on the air pressure difference between the first air pressure chamber 12 and the second air pressure chamber 13, and a fifth force on one side in the X direction based on the distortion of the feedback spring 6. The cylinder 5 stops at a position where the fourth force and the fifth force coincide.

[0059] At the end of positioning of the cylinder 5 shown in FIG. 10, the movement of the flapper 21 settles down and stops in a state where it is slightly tilted with respect to the Z direction based on the current flowing through the coils 22 and 23. At this time, the first output port CY1 moves away from both the first gas supply port Ps1 and the exhaust port Ex, and the second output port CY2 moves away from both the second gas supply port Ps2 and the exhaust port Ex. Then, the air pressure of the first nozzle 9 and the second nozzle 10 becomes medium pressure, and the air pressure of the first nozzle 9 becomes slightly higher than the air pressure of the second nozzle 10, and the air pressure of the third pressure chamber 112 and the fourth pressure chamber 113 becomes medium pressure, and the air pressure of the third pressure chamber 112 becomes slightly higher than the air pressure of the fourth pressure chamber 113. Also, the first pressure chamber 12 and the second pressure chamber 13 become medium pressure, and the air pressure of the first pressure chamber 12 becomes slightly higher than the air pressure of the second pressure chamber 13. Then, the cylinder 5 comes to a standstill in a state in which the feedback spring 6 is deflected to the other side in the X direction (to the left in the X direction).

[0060] When the armature 20 rotates in the direction indicated by the arrow A in FIG. 4B, the operation is the same as that described in FIG. 8 to FIG. 10 except that the cylinder 5 moves to one side (right side) in the X direction instead of the other side (left side) in the X direction. The pressure difference between the first air pressure chamber 12 and the second air pressure chamber 13 corresponds one-to-one to the direction and magnitude of the current flowing through the coils 22 and 23. Therefore, by controlling the direction and magnitude of the current flowing through the coils 22 and 23 with high precision, the X direction dimension of the protruding portion protruding in the X direction from the first closing portion 34 in the small diameter portion 5e can be adjusted with high precision. In addition, since the servo cylinder 101 includes the flow booster valve 150, the flow rate per unit of gas can be increased. Therefore, the moving speed of the cylinder 5 can be increased, and the responsiveness of the cylinder 5 can be improved.

[0061] According to the second embodiment, the air pressure difference generating mechanism 4 includes an armature 20 extending linearly, a flapper 21 that is integral with the armature 20 and forms a T-shaped member together with the armature 20, a first coil 22 that is wound on one side of the center of the armature 20, a second coil 23 that is wound on the other side of the center of the armature 20, a first nozzle 9 and a second nozzle 10 that extend in a direction substantially perpendicular to the extension direction of the flapper 21, have substantially the same distance from the flapper 21, and face each other in the perpendicular direction via the flapper 21 when no current flows through the first coil 22 and the second coil 23, and a flow rate booster valve 150.

[0062] The flow booster valve 150 also includes a sleeve 151 having two gas supply ports Ps1, Ps2, an exhaust port Ex, and two output ports CY1, CY2, a spool 105 that can slide within the sleeve 151, a third air pressure chamber 112 provided outside a first axial side (one side) of the spool 105, a fourth air pressure chamber 113 provided outside a second axial side (the other side) of the spool 105, and a force application section (first to fourth permanent magnets 161, 162, 163, 164) that applies an axial force to the spool 105.

[0063] The spool 105 also has three large-diameter lands 134, 135, 136 spaced apart in the axial direction, and two stems 138, 139 having smaller outer diameters than the lands 134, 135, 136 and connecting adjacent lands 134, 135, 136. The force application unit also applies a force to the spool 105 to position the spool 105 at a position where the output ports CY1, CY2 do not communicate with both the gas supply ports Ps1, Ps2 and the exhaust port Ex.

[0064] The servo cylinder 101 further includes a first back pressure passage 115 that connects one of the first nozzle 9 and the second nozzle 10 to one of the third pressure chamber 112 and the fourth pressure chamber 113, a second back pressure passage 116 that connects the other of the first nozzle 9 and the second nozzle 10 to the other of the third pressure chamber 112 and the fourth pressure chamber 113, a third back pressure passage 117 that connects one of the two output ports CY1, CY2 to one of the first pressure chamber 12 and the second pressure chamber 13, and a fourth back pressure passage 118 that connects the other of the two output ports CY1, CY2 to the other of the first pressure chamber 12 and the second pressure chamber 13.

[0065] When the spool 105 is in the neutral position where no current flows through the first coil 22 and the second coil 23, the output ports CY1, CY2 are not connected to either the gas supply ports Ps1, Ps2 or the exhaust port Ex. On the other hand, when the spool 105 moves axially from the neutral position, one of the two output ports CY1, CY2 is connected to the exhaust port Ex via one of the two stems 138, 139, and the other of the two output ports CY1, CY2 is connected to one of the two gas supply ports Ps1, Ps2 via the other of the two stems 138, 139.

[0066] According to the second embodiment, the flow rate per unit time of the gas flowing into the first pressure chamber 12 and the second pressure chamber 13 can be increased when the cylinder 5 is moved by the operation of the flow booster valve 150. Therefore, the moving speed of the cylinder 5 can be increased, and the responsiveness of the servo cylinder 1 can be improved.

[0067] The present disclosure is not limited to the above-described embodiment and its modified examples, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents.

[0068] For example, in the above embodiment, the air pressure difference generating mechanism 4 has a pair of nozzles 9, 10. However, the air pressure difference generating mechanism may have a jet pipe. In this configuration, when the jet pipe is tilted toward one of the control ports by a driving device such as a torque motor, more of the gas being sprayed from the nozzle flows into the control port on the tilted side, which causes the pressure balance between the two air pressure chambers to be lost and the cylinder to be displaced toward the lower pressure side. It goes without saying that even in this case, the jet pipe and the cylinder are connected by a feedback spring.

[0069] In the above embodiment, the force applying portion of the flow booster valve 150 is configured with two permanent magnets 161, 162, 163, and 164, but the force applying portion of the flow booster valve may be configured with two springs (for example, coil springs). In this case, one spring is arranged to connect the end face of the spool on the first axial side to the end face of the closing portion on the first axial side, and the other spring is arranged to connect the end face of the spool on the second axial side to the end face of the closing portion on the second axial side.

[0070] In the above embodiment, the feedback spring 6 extends linearly when no external force is applied. However, the feedback spring does not have to extend linearly when no external force is applied. FIG. 11 is a diagram for explaining a feedback spring 206 of a first modified example, where FIG. 11(a) is a diagram showing a side view of the feedback spring 206 when viewed from the X direction, and FIG. 11(b) is a diagram showing a front view of the feedback spring 206 when viewed from the X direction. FIG. 12 is a diagram for explaining a feedback spring 306 of a second modified example, where FIG. 12(a) is a diagram showing a side view of the feedback spring 306 when viewed from the X direction, and FIG. 12(b) is a diagram showing a front view of the feedback spring 306 when viewed from the X direction.

[0071] As shown in Figs. 11(a) and 11(b), the feedback spring 206 has a curved portion 206a that moves in a meandering manner at a location other than both ends. The curved portion 206a has low strength and is easily displaced. Also, as shown in Figs. 12(a) and 12(b), the feedback spring 306 has a thin portion 306a that is thin at a location other than both ends. The thin portion 306a is formed, for example, by press molding. The thin portion 306a has low strength and is easily displaced. The curved portion 206a and the thin portion 306a are examples of an easily displaceable portion. By forming an easily displaceable portion at a location other than both ends of the feedback springs 206 and 306, the stroke of the feedback springs 206 and 306 can be increased, and the control range in the position control of the cylinder can be widened. [Explanation of symbols]

[0072] 1,101 servo cylinder, 2 cover, 3 housing, 4 air pressure difference generating mechanism, 5 cylinder, 5a medium diameter portion, 5b small diameter portion, 5c annular groove, 5d large diameter portion, 5e small diameter portion, 6,206,306 feedback spring, 9 first nozzle, 10 second nozzle, 12 first air pressure chamber, 13 second air pressure chamber, 15,115 first back pressure path, 16,116 second back pressure path, 18 cylinder sliding chamber, 19 step portion, 20 armature, 20a one side end of armature, 20b other side end of armature, 21 flapper, 22 first coil, 23 second coil, 25 upper magnetic pole, 25a,26a pole, 26 lower magnetic pole, 30 First fixed orifice, 31 Second fixed orifice, 34 First closing portion, 35 Cylinder hole, 36 Second closing portion, 47 Filter, 105 Spool, 110 Cylinder body, 112 Third pressure chamber, 113 Fourth pressure chamber, 117 Third back pressure passage, 118 Fourth back pressure passage, 134 First land, 135 Second land, 136 Third land, 138 First stem, 139 Second stem, 150 Flow rate booster valve, 151 Sleeve, 152 Spool sliding chamber, 157 Third closing portion, 158 Fourth closing portion, 161 First permanent magnet, 162 Second permanent magnet, 163 Third permanent magnet, 164 Fourth permanent magnet, 206a Curved portion, 306a Thin portion, CY1 First output port, CY2 Second output port; Ex Exhaust port; Ps1 First gas supply port; Ps2 Second gas supply port.

Claims

1. A housing having a cylinder sliding chamber extending in one direction; a cylinder that is disposed within the cylinder sliding chamber so as to be slidable in the one direction relative to the cylinder sliding chamber, the cylinder including a recess provided on an outer circumferential surface, a large diameter portion provided on a first side of the recess in the one direction, and a small diameter portion that is connected to the first side of the large diameter portion in the one direction via a step portion and has a smaller diameter than the large diameter portion; a first air pressure chamber containing a gas that applies a force to the step portion in the second direction; a second air pressure chamber in which a gas is accommodated that applies a force on the first side in the one direction to an end surface on the second side in the one direction of the cylinder; an air pressure difference generating mechanism for generating an air pressure difference between the air pressure in the first air pressure chamber and the air pressure in the second air pressure chamber; a feedback spring having one end fixed to the air pressure difference generating mechanism and the other end accommodated in the recess; A servo cylinder comprising:

2. 2. The servo cylinder according to claim 1, wherein the air pressure difference generating mechanism includes: an armature extending linearly; a flapper provided integrally with the armature and constituting a T-shaped member together with the armature; a first coil wound on one side of a center of the armature; a second coil wound on the other side of the center of the armature; a first nozzle and a second nozzle extending in a direction substantially perpendicular to an extension direction of the flapper, the first nozzle and the second nozzle being at substantially the same distance from the flapper and facing each other in the perpendicular direction via the flapper when no current flows through the first coil and the second coil; a first back pressure path communicating the first nozzle with the first air pressure chamber; and a second back pressure path communicating the second nozzle with the second air pressure chamber.

3. the air pressure difference generating mechanism includes an armature extending linearly, a flapper provided integrally with the armature and constituting a T-shaped member together with the armature, a first coil wound on one side of the center of the armature, a second coil wound on the other side of the center of the armature, a first nozzle and a second nozzle extending in a direction substantially perpendicular to the extension direction of the flapper, the distances from the flapper being substantially the same and facing each other in the perpendicular direction via the flapper when no current flows through the first coil and the second coil, and a flow rate booster valve, the flow rate booster valve includes: a sleeve having two gas supply ports, an exhaust port, and two output ports; a spool slidable within the sleeve; a third air pressure chamber provided outside a first axial side of the spool; a fourth air pressure chamber provided outside a second axial side of the spool; and a force applying portion that applies a force in the axial direction to the spool; The spool has three lands of large diameter spaced apart in the axial direction and two stems having smaller outer diameters than the lands and connecting adjacent lands, the force application unit applies a force to the spool to position the spool at a position where the output port does not communicate with both the gas supply port and the exhaust port; a first back pressure passage that connects one of the first nozzle and the second nozzle to one of the third pressure chamber and the fourth pressure chamber; a second back pressure passage that connects the other of the first nozzle and the second nozzle to the other of the third pressure chamber and the fourth pressure chamber; a third back pressure passage that connects one of the two output ports to one of the first pressure chamber and the second pressure chamber; a fourth back pressure passage that connects the other of the two output ports to the other of the first pressure chamber and the second pressure chamber, 2. The servo cylinder of claim 1, wherein in a neutral position of the spool where no current flows through the first coil and the second coil, the output port is not in communication with both the gas supply port and the exhaust port, whereas when the spool moves axially from the neutral position, one of the two output ports is in communication with the exhaust port via one of the two stems, and the other of the two output ports is in communication with one of the two gas supply ports via the other of the two stems.

4. 4. The servo cylinder according to claim 1, wherein the feedback spring has an easily displaceable portion at a location other than both ends.

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