Fluid pressure cylinder

Abstract

The present invention provides a fluid pressure cylinder that can be applied to small fluid pressure cylinders and includes a position detection mechanism capable of accurately detecting the position of the output rod. [Solution] In a fluid pressure cylinder, the piston member includes a piston portion fitted to the inner circumference of the cylinder body 2, an output rod extending from the piston portion to the outside of the cylinder body, and an auxiliary rod 34 extending from the piston portion to the opposite side of the output rod. The output rod and the auxiliary rod are provided coaxially so as to extend in a first direction. The valve member 8 is provided on the outer circumference of the auxiliary rod and has a cylindrical portion 8A extending in the first direction. The opening and closing of the fluid passage 11A by the valve member is switched in conjunction with the reciprocating motion of the auxiliary rod in the first direction. The position of the piston member can be detected based on the open / closed state of the fluid passage.

Description

Technical Field

[0001] The present technology relates to a fluid pressure cylinder.

Background Art

[0002] There has conventionally been known a fluid pressure cylinder capable of detecting the position of an output rod by opening and closing a detection valve as the output rod moves.

[0003] Examples of conventional fluid pressure cylinders include those described in JP-A-2003-305626 (Patent Document 1), JP-A-2014-108490 (Patent Document 2), JP-A-2014-114898 (Patent Document 3), JP-A-2014-129864 (Patent Document 4), and European Patent Application Publication No. 4296001 (Patent Document 5).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0005] The position detection mechanism of the output rod is required to accurately perform position detection. In addition, there is a demand for miniaturization of the fluid pressure cylinder.

[0006] The objective of this technology is to provide a fluid pressure cylinder that can be applied to small fluid pressure cylinders and includes a position detection mechanism capable of accurately detecting the position of the output rod. [Means for solving the problem]

[0007] This technology provides the following fluid pressure cylinders.

[0008] [1] A fluid pressure cylinder comprising a cylinder body, a piston member reciprocating in a first direction relative to the cylinder body, a working medium chamber provided inside the cylinder body for supplying a working medium to drive the piston member, a valve member provided so as to face a space communicating with the working medium chamber, and a fluid passage opened and closed by the valve member, wherein the piston member includes a piston portion fitted to the inner circumference of the cylinder body, an output rod extending from the piston portion to the outside of the cylinder body, and an auxiliary rod extending from the piston portion to the opposite side of the output rod, the output rod and the auxiliary rod being provided coaxially so as to extend in the first direction, the valve member being provided on the outer circumference of the auxiliary rod and having a cylindrical portion extending in the first direction, the opening and closing of the fluid passage by the valve member being switched in conjunction with the reciprocating motion of the auxiliary rod in the first direction, and the position of the piston member being detectable based on the open / closed state of the fluid passage.

[0009] [2] The fluid pressure cylinder according to [1], wherein the valve member has an end face at the end opposite to the working medium chamber in the first direction, and further comprises a valve seat that abuts against the end face from the first direction.

[0010] [3] The fluid pressure cylinder according to [2], wherein the pressure of the working medium biases the valve member toward the valve seat.

[0011] [4] The fluid pressure cylinder according to [2], further comprising an elastic member that biases the valve member toward the valve seat.

[0012] [5] A fluid pressure cylinder according to any one of [1] to [4], further comprising a plurality of spheres provided on the outer circumference of the auxiliary rod, wherein the plurality of spheres move in a direction intersecting the first direction in conjunction with the reciprocating motion of the auxiliary rod in the first direction, thereby driving the valve member in the first direction and switching the opening and closing of the fluid passage by the valve member.

[0013] [6] A fluid pressure cylinder according to any one of [2] to [5], further comprising an outer peripheral member provided on the outer circumference of the valve member, wherein the valve member has an outer peripheral surface extending in the first direction, and is capable of realizing a first state in which the end face abuts against the valve seat, a second state in which the end face is spaced away from the valve seat and the outer peripheral surface is spaced away from the outer peripheral member, and a third state in which the end face is spaced away from the valve seat and the outer peripheral surface is close to the outer peripheral member. [Effects of the Invention]

[0014] This technology provides a fluid pressure cylinder that can be applied to small fluid pressure cylinders and includes a position detection mechanism capable of accurately detecting the position of the output rod. [Brief explanation of the drawing]

[0015] [Figure 1] This is a cross-sectional view showing the unclamped state of the swing clamp according to Embodiment 1. [Figure 2] This is a cross-sectional view showing the state in which the piston member is at its lowered end in the swing clamp according to Embodiment 1. [Figure 3] This is an enlarged view of part III in Figure 1. [Figure 4] This is an enlarged view of section IV in Figure 2. [Figure 5] This is a cross-sectional view showing the unclamped state of the swing clamp according to Embodiment 2. [Figure 6] This is a cross-sectional view showing the clamped state of the swing clamp according to Embodiment 2. [Figure 7] This is an enlarged view of section VII in Figure 5. [Figure 8] It is an enlarged view of part VIII in FIG. 6. [Figure 9] It is a cross-sectional view showing the unclamped state of the swing clamp according to Embodiment 3. [Figure 10] It is an enlarged view of part X in FIG. 9. [Figure 11] It is a cross-sectional view showing the intermediate state of the operation of the piston member in the swing clamp according to Embodiment 3. [Figure 12] It is an enlarged view of part XII in FIG. 11. [Figure 13] It is a cross-sectional view showing the clamped state of the swing clamp according to Embodiment 3. [Figure 14] It is an enlarged view of part XIV in FIG. 13. [Figure 15] It is a cross-sectional view showing the state where the piston member is at the lower end in the swing clamp according to Embodiment 3. [Figure 16] It is an enlarged view of part XVI in FIG. 15. [Figure 17] It is a cross-sectional view showing the internal structure of the hydraulic cylinder according to Embodiment 4. [Figure 18] It is a cross-sectional view showing the link clamp according to Embodiment 5.

Mode for Carrying Out the Invention

[0016] The embodiments of the present technology will be described below. In addition, the same reference numerals may be given to the same or corresponding parts, and the description thereof may not be repeated.

[0017] In addition, in the embodiments described below, when referring to the number, amount, etc., unless otherwise specified, the scope of the present technology is not necessarily limited to such number, amount, etc. Also, in the following embodiments, each component is not necessarily essential for the present technology, unless otherwise specified. Further, the present technology is not necessarily limited to those that exhibit all the operational effects mentioned in the present embodiment.

[0018] In this specification, the terms "comprise," "include," and "have" are in open-ended form. That is, if a configuration includes one configuration, it may also include other configurations, or it may not.

[0019] Furthermore, where geometric terms and terms describing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° oblique," "coaxial," and "alongside," these terms allow for manufacturing tolerances or slight variations. Where terms describing relative positional relationships, such as "upper" and "lower," are used in this specification, these terms are used to indicate the relative positional relationship in a single state, and the relative positional relationship may be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by inverting the entire mechanism upside down).

[0020] In the following embodiments, a "clamping device" is described as an example of a "fluid pressure cylinder," but the "fluid pressure cylinder" relating to this technology is not limited to a "clamping device." Examples of applications for a "fluid pressure cylinder" other than a "clamping device" include a "transporting device" for moving a workpiece, an "assembly device" for assembling two parts by press-fitting using the force of the cylinder, and an "inspection device" for detecting the presence or absence of a workpiece.

[0021] According to the following embodiment, the "fluid pressure cylinder" can be miniaturized, particularly in the radial direction. Furthermore, accurate position detection can be performed in a small "fluid pressure cylinder". The piston diameter assumed in the "fluid pressure cylinder" according to the following embodiment is preferably about 4 mm or more (more preferably about 6 mm or more), and preferably about 30 mm or less (more preferably about 20 mm or less). However, in this technology, the piston diameter is not limited to the above numerical range.

[0022] (Embodiment 1) The structure of the swing clamp 100 according to Embodiment 1 will be described using Figures 1 to 4. Figure 1 is a cross-sectional view showing the unclamped state (clamp released state) of the swing clamp 100.

[0023] As shown in Figure 1, the swing clamp 100 includes a cylinder body 2 provided within the base 1, a piston member 3, an annular member 4, a lower cylinder 5, a sphere 6, a sphere 7 (engaging device), a valve member 8, and a plate 9. In addition to the cylinder body 2, the annular member 4, the lower cylinder 5, and the plate 9 are also included in the "cylinder body".

[0024] A fluid passage 11 and a working fluid passage 12 are formed in the base 1. The fluid passage 11 and the working fluid passage 12 communicate with the internal space of the cylinder body 2. The fluid passage 11 is a passage for supplying and discharging fluid for detecting the position of the piston member 3. The fluid passage 11 is opened and closed by a valve member 8. The working fluid passage 12 is a passage for supplying and discharging the working fluid that operates the swing clamp 100.

[0025] Inside the cylinder body 2 are cylinder chambers 2A and 2B (working medium chambers). A working medium that drives the piston member 3 downward is supplied to cylinder chamber 2A via passage 12A. A working medium that drives the piston member 3 upward is supplied to cylinder chamber 2B via passage 12B.

[0026] A hydraulic fluid may be used as the working fluid. The working fluid may also be air. The pressure of the working fluid supplied to cylinder chambers 2A and 2B is not particularly limited in this technology.

[0027] In the examples shown in Figures 1 to 4, a gap is provided between the cylinder body 2 and the plate 9. This allows the cylinder chamber 2B and the passage 12B to communicate. However, the scope of this technology is not limited to the above structure. For example, the cylinder chamber 2B and the passage 12B may be communicated by providing a gap between the annular member 4 and the plate 9, or by providing a lateral hole (a hole extending in the left-right direction in the figure) in the plate 9.

[0028] The piston member 3 is reciprocable in the vertical direction (first direction) relative to the cylinder body 2. The piston member 3 includes an output rod 31, a pivoting mechanism 32, a piston portion 33, and an auxiliary rod 34.

[0029] The output rod 31 extends upward from the piston portion 33 to the outside of the cylinder body 2. The pivoting mechanism 32 pivots the piston member 3 and the clamp arm 3A in accordance with the vertical movement of the piston member 3. The piston portion 33 is fitted to the inner circumference of the cylinder body 2. The auxiliary rod 34 extends downward from the piston portion 33. That is, the auxiliary rod 34 extends from the piston portion 33 to the opposite side of the output rod 31. The output rod 31 and the auxiliary rod 34 are provided coaxially.

[0030] A clamp arm 3A is attached to the upper end of the output rod 31. The clamp arm 3A is secured by a nut 3B.

[0031] The swivel mechanism 32 has a straight groove 32A and a swivel groove 32B formed on the outer circumferential surface of the piston member 3. A sphere 6 held by the cylinder body 2 engages with the straight groove 32A and the swivel groove 32B. In the state shown in Figure 1, the sphere 6 is engaged with the swivel groove 32B. The straight groove 32A extends in the vertical direction, and the swivel groove 32B extends in a spiral shape. The lower end of the straight groove 32A and the upper end of the swivel groove 32B are continuous. Preferably, multiple (for example, two or three) straight grooves 32A, swivel groove 32B and spheres 6 are provided on the outer circumference of the piston member 3 so as to be arranged at equal intervals in the circumferential direction.

[0032] The piston portion 33 divides the space within the cylinder body 2 into cylinder chamber 2A and cylinder chamber 2B. When hydraulic pressure (working medium pressure) is supplied to cylinder chamber 2A, the piston portion 33 is driven downward. When hydraulic pressure is supplied to cylinder chamber 2B, the piston portion 33 is driven upward. The auxiliary rod 34 drives the valve member 8 in conjunction with its vertical reciprocating motion.

[0033] In this embodiment, an example is shown in which the output rod 31, the pivoting mechanism 32, the piston 33, and the auxiliary rod 34 are made from a single integrated material. However, the scope of this technology is not limited to this, and for example, the auxiliary rod 34, which is made from a separate material, may be fixed to the piston 33 and integrated.

[0034] The annular member 4 and the lower cylinder 5 are positioned below the cylinder body 2. Multiple spheres 7 are provided on the outer circumference of the auxiliary rod 34, arranged in a circumferential direction. The spheres 7 move radially around the auxiliary rod 34 in conjunction with the vertical reciprocating motion of the auxiliary rod 34, driving the valve member 8.

[0035] The valve member 8 switches the opening and closing of the fluid passage 11. The swing clamp 100 according to this embodiment is capable of detecting the position of the piston member 3 based on the open / closed state of the fluid passage 11. The plate 9 is provided between the cylinder body 2 and the valve member 8. However, the cylinder chamber 2B is also in communication with the space below the plate 9. That is, the upper surface of the valve member 8 faces the space that communicates with the cylinder chamber 2B.

[0036] Figure 2 is a cross-sectional view showing the state in which the piston member 3 is at its lowered end in the swing clamp 100. In the state shown in Figure 2, the sphere 6 is engaged with the upper end of the straight groove 32A. Also, the clamp arm 3A has rotated 90° from the state shown in Figure 1. Note that the rotation angle of the clamp arm 3A is not limited to 90°.

[0037] Figure 3 is an enlarged view of part III in Figure 1. Figure 4 is an enlarged view of part IV in Figure 2.

[0038] As shown in Figures 3 and 4, a small-diameter portion 34A is formed at the tip of the auxiliary rod 34. The annular member 4 (outer peripheral member) has radially extending through holes 4A and 4B and a valve seat 4C. Through hole 4A communicates with passage 11A, and through hole 4B communicates with passage 11B. The valve seat 4C is formed to extend horizontally. That is, the valve seat 4C is provided to extend in a planar direction that intersects (preferably approximately perpendicular to) the direction of movement (vertical direction) of the valve member 8. The valve member 8 contacts the valve seat 4C from above.

[0039] The lower cylinder 5 (inner circumferential member) includes a wall portion 5A and a receiving hole 5B formed on the inner circumference of the wall portion 5A. A gap 5C is formed between the outer circumferential surface of the wall portion 5A and the inner circumferential surface of the annular member 4. The gap 5C connects the through holes 4A and 4B of the annular member 4. As a result, the passages 11A and 11B of the fluid passage 11 communicate with each other.

[0040] The valve member 8 has a cylindrical portion 8A, an inclined surface 8B, and end faces 8C and 8D. The cylindrical portion 8A slides vertically against the inner circumferential surface of the annular member 4 and the outer circumferential surface of the wall portion 5A of the lower cylinder 5. The sliding surfaces on the outer and inner circumferential sides of the cylindrical portion 8A are sealed by a sealing member. Therefore, the upper end face 8C of the valve member 8 faces the space where the working fluid pressure of the cylinder chamber 2B acts, and the lower end face 8D of the valve member 8 is located in the middle of the fluid passage 11.

[0041] In one example, pressurized air is supplied to passage 11A of the fluid passage 11. In the example according to this embodiment, it is preferable that the pressure of the pressurized air is lower than the pressure of the working fluid supplied to the cylinder chambers 2A and 2B. However, in this technology, the air pressure supplied to passage 11A is not particularly limited.

[0042] Passage 11B communicates with the outside space. At this time, a pressure detection unit (not shown) is provided to measure the pressure in passage 11A. When valve member 8 closes and fluid passage 11 is closed, the pressure in passage 11A rises, and when valve member 8 opens and passages 11A and 11B communicate, the pressure in passage 11A decreases. By detecting the pressure change in passage 11A, the state of valve member 8 can be detected. Alternatively, pressurized air (fluid) may be supplied to passage 11B to connect passage 11A to the outside space.

[0043] In the state shown in Figure 3 (unclamped state), the sphere 7 is adjacent to the small-diameter portion 34A of the auxiliary rod 34 with a small gap in between, so no radial force acts on the sphere 7 from the auxiliary rod 34. At this time, the pressure of the working fluid supplied to the cylinder chamber 2B acts on the end face 8C of the valve member 8, and the valve member 8 is biased downward. As a result, the end face 8D comes into contact with the valve seat 4C, the fluid passage 11 is closed, and the air pressure in the passage 11A increases.

[0044] When the working fluid pressure is supplied to the cylinder chamber 2A from the state shown in Figure 3, causing the piston member 3 to descend, the small-diameter portion 34A of the auxiliary rod 34 is housed in the housing hole 5B of the lower cylinder 5, as shown in Figure 4, and the upper portion of the auxiliary rod 34 (the portion with a larger diameter than the small-diameter portion 34A) comes into contact with the sphere 7, causing the sphere 7 to be pressed radially outward. At this time, the sphere 7 comes into contact with the inclined surface 8B of the valve member 8, biasing the valve member 8 upward. As a result, the end face 8D of the valve member 8 separates from the valve seat 4C, the passages 11A and 11B of the fluid passage 11 come into contact, and the air pressure in passage 11A decreases.

[0045] However, in this technology, the position detection mechanism for the piston member 3 is not limited to detection by pressure changes of the "pressurized air" described above. For example, the position of the piston member 3 may be detected by measuring the flow rate of the fluid in the fluid passage 11 and detecting the "decrease in flow rate" in the closed state and the "increase in flow rate" in the open state.

[0046] As described above, in the swing clamp 100 according to this embodiment, the valve member 8 is biased downward (in the valve closing direction) by utilizing the working fluid pressure of the cylinder chamber 2B, while when the piston member 3 moves downward, the position of the piston member 3 including the output rod 31 can be detected by moving the valve member 8 upward (in the valve opening direction) via the auxiliary rod 34 and the sphere 7.

[0047] Furthermore, by employing a poppet-type valve structure in which the end face 8D of the valve member 8 and the valve seat 4C are in contact, the pressure difference between the closed and open states can be made more pronounced compared to the case where a spool-type valve structure is employed, thereby improving the accuracy of position detection. Also, when attempting to perform position detection simultaneously in a large number of fluid pressure cylinders, even if the gaps in the valve structure of each individual fluid pressure cylinder are minute, the cumulative total (sum of gaps) tends to be large. In this respect, by employing a poppet-type valve structure, it is possible to eliminate (or minimize) the minute gaps that occur in a spool-type valve structure, so accurate position detection can be performed even when performing position detection simultaneously in a large number of fluid pressure cylinders. However, the scope of this technology is not limited to poppet-type valve structures.

[0048] Furthermore, in the swing clamp 100 according to this embodiment, since the cylindrical valve member 8 is provided on the outer circumference of the auxiliary rod 34, it is possible to promote miniaturization in the radial direction compared to a structure in which the auxiliary rod and valve body are arranged side by side in the radial direction.

[0049] Furthermore, compared to the case where the valve body is provided on the inner circumference of the auxiliary rod, the diameter of the auxiliary rod 34 can be reduced, thus promoting miniaturization in the radial direction.

[0050] Furthermore, it is preferable that the diameter of the auxiliary rod 34 is smaller than the diameter of the output rod 31. However, in this technology, the diameter of the auxiliary rod 34 is not particularly limited.

[0051] Furthermore, in the swing clamp 100 according to this embodiment, the valve member 8 is provided such that its end face 8C faces the space communicating with the cylinder chamber 2B. Therefore, there is no need to provide a sealing member on the auxiliary rod 34 to separate the fluid passage 11 and the working medium passage 12, and the sliding resistance of the piston member 3 can be reduced.

[0052] In fluid pressure cylinders that have been miniaturized by reducing the piston diameter, the effect of sliding resistance tends to be greater. Reducing the sliding resistance of the piston member 3 is effective in miniaturized fluid pressure cylinders (especially in the radial direction). In the swing clamp 100 according to this embodiment, it is possible to promote miniaturization, especially in the radial direction, while suppressing a decrease in clamping force (achieving a clamping force equivalent to that without the auxiliary rod 34). Furthermore, accurate position detection can be performed in the miniaturized fluid pressure cylinder.

[0053] The sphere 7 may be a steel ball, a ceramic ball, or made of another material. In this technology, the form of the engaging device provided on the outer circumference of the auxiliary rod 34 is not limited to a sphere 7, and may have a shape other than a sphere (for example, a pin shape). It is preferable that the shapes of the multiple engaging devices arranged in the circumferential direction are substantially the same.

[0054] (Embodiment 2) Next, the swing clamp 100 according to Embodiment 2 will be described with reference to Figures 5 to 8.

[0055] Figures 5 and 6 are cross-sectional views showing the unclamped state (clamp released state) and the clamped state (state with the workpiece W clamped) of the swing clamp 100 according to this embodiment, respectively. Figure 7 is an enlarged view of part VII in Figure 5 (unclamped state), and Figure 8 is an enlarged view of part VIII in Figure 6 (clamped state).

[0056] As shown in Figures 5 to 8, the swing clamp 100 according to this embodiment is a modified version of the swing clamp 100 according to Embodiment 1, and is provided with a spring 10 (elastic member) which is placed between the plate 9 and the end face 8C of the valve member 8 and biases the valve member 8 toward the valve seat 4C in the closing direction.

[0057] In the state shown in Figure 7 (unclamped state), the auxiliary rod 34 contacts the sphere 7, and the sphere 7 is pressed radially outward. At this time, the sphere 7 contacts the inclined surface 8B of the valve member 8, biasing the valve member 8 upward. The valve member 8 is driven upward against the downward force due to the biasing force of the spring 10 and the working fluid pressure, and the end face 8D of the valve member 8 separates from the valve seat 4C. As a result, passages 11A and 11B of the fluid passage 11 are connected, and the air pressure in passage 11A decreases.

[0058] When the working fluid pressure is supplied to the cylinder chamber 2A from the state shown in Figure 7, causing the piston member 3 to descend, the large-diameter portion of the auxiliary rod 34 is housed in the housing hole 5B of the lower cylinder 5, as shown in Figure 8, and the small-diameter portion 34B of the auxiliary rod 34 is adjacent to the sphere 7 with a small gap between them. Therefore, no radial force acts on the sphere 7 from the auxiliary rod 34. At this time, the biasing force of the spring 10 acts on the end face 8C of the valve member 8, biasing the valve member 8 downwards. As a result, the end face 8D comes into contact with the valve seat 4C, the fluid passage 11 is closed, and the air pressure in the passage 11A increases.

[0059] As described above, in the swing clamp 100 according to this embodiment, the spring 10 is used to bias the valve member 8 downward (in the valve closing direction), while when the piston member 3 moves upward, the auxiliary rod 34 and the sphere 7 move the valve member 8 upward (in the valve opening direction), thereby enabling the detection of the position of the piston member 3 including the output rod 31.

[0060] Furthermore, if the piston member 3 passes the position shown in Figure 8 (clamping position) and descends further, the large-diameter portion of the auxiliary rod 34 will again come into contact with the sphere 7, and the sphere 7 will be pressed radially outward. As a result, the valve member 8 will be driven upward, and the end face 8D of the valve member 8 will separate from the valve seat 4C. That is, the valve member 8 will switch to an open state, and the air pressure in the passage 11A will decrease. By detecting this state, it is possible to detect that a misclamping operation has occurred.

[0061] Other matters are the same as in Embodiment 1, so a detailed explanation will not be repeated.

[0062] (Embodiment 3) Next, the swing clamp 100 according to Embodiment 3 will be described with reference to Figures 9 to 16.

[0063] Figure 9 is a cross-sectional view showing the unclamped state (clamp released state), and Figure 10 is an enlarged view of section X in Figure 9. Figure 11 is a cross-sectional view showing the piston member 3 in the middle of operation (moving towards the clamping position), and Figure 12 is an enlarged view of section XII in Figure 11. Figure 13 is a cross-sectional view showing the clamped state (clamping the workpiece W), and Figure 14 is an enlarged view of section XIV in Figure 13. Figure 15 is a cross-sectional view showing the piston member 3 at its lowered end (past the clamping position), and Figure 16 is an enlarged view of section XVI in Figure 15.

[0064] The swing clamp 100 according to this embodiment is a modified version of the swing clamp 100 according to embodiments 1 and 2, and uses the end face 8D and outer peripheral surface 8E of the valve member 8 to switch between opening and closing, achieving a completely closed valve state (first state), a completely open valve state (second state), and an intermediate state (third state) that is closed but not completely closed.

[0065] In the state shown in Figures 9 and 10 (unclamped state), the small-diameter portion 34A of the auxiliary rod 34 contacts the sphere 7, and the sphere 7 is pressed radially outward. At this time, the sphere 7 contacts the inclined surface 8B of the valve member 8, biasing the valve member 8 upward. The valve member 8 is driven upward against the downward force due to the biasing force of the spring 10 and the working fluid pressure, and the end face 8D of the valve member 8 separates from the valve seat 4C. On the other hand, the outer circumferential surface 8E of the valve member 8 is close to the inner circumferential surface of the annular member 4 (outer circumferential member) with a small gap in between (example of gap width: approximately 0.01 mm to 0.05 mm). That is, the valve member 8 is in an intermediate state (third state) where the fluid passage 11 is closed, but not completely closed.

[0066] From the state shown in Figures 9 and 10, when the working fluid pressure is supplied to the cylinder chamber 2A and the piston member 3 is lowered, the auxiliary rod 34, which has a larger diameter than the small diameter portion 34A, comes into contact with the sphere 7, the sphere 7 is further pressed radially outward, the valve member 8 is driven further upward, and the outer circumferential surface 8E of the valve member 8 separates from the inner circumferential surface of the annular member 4 (outer circumferential member). In other words, the valve member 8 switches to a fully open state (second state). As a result, passages 11A and 11B of the fluid passage 11 are completely connected, and the air pressure in passage 11A decreases.

[0067] From the state shown in Figures 11 and 12, when the piston member 3 is lowered further to the state shown in Figures 13 and 14 (clamped state), the small-diameter portion 34B, which is even smaller in diameter than the small-diameter portion 34A, is adjacent to the sphere 7. At this time, there is a small gap between the small-diameter portion 34B and the sphere 7, and no radial force acts on the sphere 7 from the auxiliary rod 34. Also, the biasing force of the spring 10 acts on the end face 8C of the valve member 8, biasing the valve member 8 downward, and the end face 8D comes into contact with the valve seat 4C. That is, the valve member 8 switches to a completely closed state (first state). As a result, the fluid passage 11 is completely closed, and the air pressure in the passage 11A increases.

[0068] From the state shown in Figures 13 and 14, when the piston member 3 is lowered further to the state shown in Figures 15 and 16 (the state where the piston member 3 is at its lowered end), the auxiliary rod 34, which has a larger diameter than the small diameter portion 34A, comes into contact with the sphere 7 again, the sphere 7 is pressed radially outward, the valve member 8 is driven upward, the end face 8D of the valve member 8 separates from the valve seat 4C, and the outer circumferential surface 8E of the valve member 8 separates from the inner circumferential surface of the annular member 4 (outer circumferential member). In other words, the valve member 8 switches to a fully open state (second state). As a result, passages 11A and 11B of the fluid passage 11 are completely connected, and the air pressure in passage 11A decreases.

[0069] In this embodiment, the air pressure in the passage 11A differs from that of the first state (completely closed valve state), the second state (completely open valve state), and the third state (closed valve state but not completely closed valve state). This makes it possible to detect three states (clamped state, unclamped state, and other states) using a single fluid passage 11.

[0070] Other states besides the clamped and unclamped states include, for example, the states shown in Figures 15 and 16 (the state in which the piston member 3 is at its lowered end), that is, the state in which the piston member 3 has passed the clamped position. By detecting the states shown in Figures 15 and 16, it is possible to detect that a misclamping operation has occurred.

[0071] Other matters are the same as in Embodiments 1 and 2, so a detailed explanation will not be repeated.

[0072] (Embodiment 4) Figure 17 is a cross-sectional view showing the internal structure of a fluid pressure cylinder according to Embodiment 4. The fluid pressure cylinder according to this embodiment is a modified version of Embodiments 1 to 3, and as shown in Figure 17, an engaging portion 4D is provided at the upper end of the annular member 4, and the cylinder body 2 and the annular member 4 are connected using a retaining ring 20. By connecting the cylinder body 2 and the annular member 4 with the retaining ring 20, the annular member 4, the lower cylinder 5, and the plate 9 can be easily removed from the base 1 when removing the cylinder body 2 from the base 1.

[0073] Other matters are the same as in Embodiments 1 to 3, so a detailed explanation will not be repeated.

[0074] (Embodiment 5) Figure 18 is a cross-sectional view showing a link clamp 200 according to Embodiment 5. The fluid pressure cylinder according to this embodiment is a modification of Embodiments 1 to 4, and as shown in Figure 18, the present technology is applied to a link clamp 200 in which the clamp arm 3A does not rotate.

[0075] As shown in Figure 18, in the link clamp 200, the clamp arm 3A is attached to the output rod 31 via a link mechanism. In the clamped state shown in Figure 18, working fluid pressure is supplied to the cylinder chamber 2B, and the piston member 3 is driven upward. At this time, no radial load acts on the sphere 7 from the auxiliary rod 34, and the valve member 8 is biased downward (in the valve closing direction) by the working fluid pressure supplied to the cylinder chamber 2B.

[0076] In this embodiment as well, similar to embodiments 1 to 4 described above, the valve member 8 is provided so as to face the space communicating with the cylinder chamber 2B, so there is no need to provide a sealing member on the auxiliary rod 34 to separate the fluid passage 11 and the working medium passage 12. Therefore, the sliding resistance of the piston member 3 can be reduced.

[0077] Furthermore, in the link clamp 200, a working fluid is supplied to the cylinder chamber 2B during clamping operation. In the link clamp 200, by not providing a sealing member on the auxiliary rod 34 and connecting the cylinder chamber 2B with the inside of the lower cylinder 5, when the piston member 3 is driven in the clamping direction (upward in the figure), the tip surface of the auxiliary rod 34 (the lower end surface in the figure) receives the pressure of the working fluid and contributes to the cylinder output. As a result, the pressure-receiving area of ​​the piston member 3 can be increased compared to the case where a sealing member is provided on the auxiliary rod 34.

[0078] Thus, the link clamp 200 according to this embodiment allows for accurate position detection in a miniaturized fluid pressure cylinder while effectively suppressing a decrease in clamping force (achieving a clamping force equivalent to that without the auxiliary rod 34).

[0079] While embodiments of the present technology have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present technology is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0080] 1 Base, 2 Cylinder body, 2A, 2B Cylinder chamber, 3 Piston member, 3A Clamp arm, 3B Nut, 4 Annular member, 4A Through hole, 4B Through hole, 4C Valve seat, 4D Engaging part, 5 Lower cylinder, 5A Wall part, 5B Housing hole, 5C Gap, 6, 7 Sphere, 8 Valve member, 8A Cylindrical part, 8B Inclined surface, 8C End face, 8D End face, 8E Outer circumference, 9 Plate, 10 Spring, 11 Fluid passage, 11A, 11B Passage, 12 Working medium passage, 12A, 12B Passage, 20 Retaining ring, 31 Output rod, 32 Swivel mechanism part, 32A Straight groove, 32B Swivel groove, 33 Piston part, 34 Auxiliary rod, 34A, 34B Small diameter part, 100 Swing clamp, 200 Link clamp.

Claims

1. Cylinder body and A piston member that can reciprocate in a first direction relative to the cylinder body, An operating medium chamber is provided inside the cylinder body, and an operating medium for driving the piston member is supplied to it. A valve member is provided so as to face the space communicating with the working medium chamber, The system includes a fluid passage that is opened and closed by the valve member, The piston member includes a piston portion fitted to the inner circumference of the cylinder body, an output rod extending from the piston portion to the outside of the cylinder body, and an auxiliary rod extending from the piston portion to the opposite side of the output rod. The output rod and the auxiliary rod are provided coaxially so as to extend in the first direction. The valve member is provided on the outer circumference of the auxiliary rod and has a cylindrical portion extending in the first direction, The opening and closing of the fluid passage by the valve member is switched in conjunction with the reciprocating motion of the auxiliary rod in the first direction. A fluid pressure cylinder capable of detecting the position of the piston member based on the open / closed state of the fluid passage.

2. The valve member has an end face at the tip opposite to the working medium chamber in the first direction, The fluid pressure cylinder according to claim 1, further comprising a valve seat that contacts the end face from the first direction.

3. The fluid pressure cylinder according to claim 2, wherein the pressure of the working medium biases the valve member toward the valve seat.

4. The fluid pressure cylinder according to claim 2, further comprising an elastic member that biases the valve member toward the valve seat.

5. The auxiliary rod further comprises a plurality of spheres provided on its outer circumference, A fluid pressure cylinder according to any one of claims 1 to 4, wherein the plurality of spheres move in a direction intersecting the first direction in conjunction with the reciprocating motion of the auxiliary rod in the first direction, thereby driving the valve member in the first direction and switching the opening and closing of the fluid passage by the valve member.

6. The valve member further comprises an outer peripheral member provided on the outer circumference of the valve member, The valve member has an outer circumferential surface extending in the first direction, A first state in which the end face abuts against the valve seat, A second state in which the end face is spaced apart from the valve seat and the outer peripheral surface is spaced apart from the outer peripheral member, A fluid pressure cylinder according to any one of claims 2 to 4, which is capable of achieving a third state in which the end face is spaced apart from the valve seat and the outer circumferential surface is close to the outer circumferential member.

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