Fluid pressure cylinder

Abstract

In this fluid pressure cylinder, a piston member includes: a piston part fitted to the inner periphery of a cylinder body; an output rod extending from the piston part to the outside of the cylinder body; and an auxiliary rod extending from the piston part to the side opposite the output rod. The output rod and the auxiliary rod are provided coaxially so as to extend in a first direction. A valve member is provided on the outer periphery of the auxiliary rod and has a tubular part extending in the first direction. The opening and closing of a fluid passage by the valve member is switched in conjunction with reciprocating movement of the auxiliary rod in the first direction. The position of the piston member can be detected on the basis of the open / closed state of the fluid passage.

Description

Fluid Pressure Cylinder

[0001] The present technology relates to fluid pressure cylinders.

[0002] 2. Description of the Related Art A fluid pressure cylinder capable of detecting the position of an output rod by opening and closing a detection valve in accordance with the movement of the output rod is conventionally known.

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

[0004] JP 2003-305626 A JP 2014-108490 A JP 2014-114898 A JP 2014-129864 A European Patent Application Publication No. 4296001

[0005] The mechanism for detecting the position of the output rod must be able to detect the position accurately. In addition, there is a demand for miniaturization of the fluid pressure cylinder.

[0006] An object of the present technology is to provide a fluid pressure cylinder that can be applied to a small fluid pressure cylinder and includes a position detection mechanism that can achieve accurate position detection of an output rod.

[0007] The present technology provides the following fluid pressure cylinder.

[0008] a working medium chamber provided inside the cylinder body to which a working medium for driving the piston member is supplied; a valve member provided facing 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 an inner periphery 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 an opposite side of the output rod, wherein the output rod and the auxiliary rod are coaxially provided to extend in the first direction, and the valve member is provided on the outer periphery of the auxiliary rod and has a cylindrical portion extending in the first direction, wherein the opening and closing of the fluid passage by the valve member is switched in conjunction with the reciprocating movement of the auxiliary rod in the first direction, and the position of the piston member can be detected based on the open / closed state of the fluid passage.

[0009] [2] The fluid pressure cylinder described in [1], wherein the valve member has an end face at a tip opposite to the working medium chamber in the first direction, and further includes a valve seat abutting the end face from the first direction.

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

[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 periphery of the auxiliary rod, wherein the valve member is driven in the first direction by the plurality of spheres moving in a direction intersecting the first direction in conjunction with the reciprocating movement of the auxiliary rod in the first direction, thereby switching between opening and closing the fluid passage by the valve member.

[0013] [6] The fluid pressure cylinder according to any one of [2] to [5], further comprising an outer peripheral member provided on the outer periphery 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 the valve seat, a second state in which the end face is separated from the valve seat and the outer peripheral surface is separated from the outer peripheral member, and a third state in which the end face is separated from the valve seat and the outer peripheral surface is close to the outer peripheral member.

[0014] According to the present technology, it is possible to provide a fluid pressure cylinder that can be applied to a small fluid pressure cylinder and includes a position detection mechanism that can realize accurate position detection of an output rod.

[0015] 11. A cross-sectional view showing an unclamped state of the swing clamp according to embodiment 1. A cross-sectional view showing a state in which the piston member is at the lowering end of the swing clamp according to embodiment 1. An enlarged view of part III in FIG. 1. An enlarged view of part IV in FIG. 2. A cross-sectional view showing an unclamped state of the swing clamp according to embodiment 2. A cross-sectional view showing a clamped state of the swing clamp according to embodiment 2. An enlarged view of part VII in FIG. 5. An enlarged view of part VIII in FIG. 6. A cross-sectional view showing an unclamped state of the swing clamp according to embodiment 3. An enlarged view of part X in FIG. 9. A cross-sectional view showing a state in which the piston member is in the middle of operation of the swing clamp according to embodiment 3. An enlarged view of part XII in FIG. 11. A cross-sectional view showing a clamped state of the swing clamp according to embodiment 3. An enlarged view of part XIV in FIG. 13. A cross-sectional view showing a state in which the piston member is at the lowering end of the swing clamp according to embodiment 3. An enlarged view of part XVI in FIG. 15. A cross-sectional view showing the internal structure of a fluid pressure cylinder according to embodiment 4. A cross-sectional view showing a link clamp according to embodiment 5.

[0016] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0017] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiments.

[0018] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0019] Furthermore, when geometric terms and terms expressing positional or directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors or slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in one state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0020] In the following embodiments, a "clamping device" will be described as an example of a "fluid pressure cylinder," but the "fluid pressure cylinder" according to the present technology is not limited to a "clamping device." Examples of uses of a "fluid pressure cylinder" other than a "clamping device" include a "transporting device" that moves a workpiece, an "assembly device" that assembles two parts by press-fitting using the force of the cylinder, and an "inspection device" that detects the presence or absence of a workpiece.

[0021] According to the following embodiments, it is possible to reduce the size of the "fluid pressure cylinder," 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 embodiments 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 the present technology, the piston diameter is not limited to the above numerical range.

[0022] 1 to 4, the structure of a swing clamp 100 according to a first embodiment will be described. Fig. 1 is a cross-sectional view showing the swing clamp 100 in an unclamped state (clamp release state).

[0023] 1, the swing clamp 100 includes a cylinder body 2 provided in a base 1, a piston member 3, an annular member 4, a lower cylinder 5, a spherical body 6, a spherical body 7 (an engaging member), 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 medium passage 12 are formed in the base 1. The fluid passage 11 and the working medium passage 12 communicate with the internal space of the cylinder body 2. The fluid passage 11 is a passage for supplying and discharging a 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 medium passage 12 is a passage for supplying and discharging a working medium that operates the swing clamp 100.

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

[0026] The working medium may be hydraulic oil or air. The pressure of the working medium supplied to the cylinder chambers 2A and 2B is not particularly limited in the present technology.

[0027] 1 to 4 , a gap is provided between the cylinder body 2 and the plate 9. This allows communication between the cylinder chamber 2B and the passage 12B. However, the scope of the present 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 the cylinder chamber 2B and the passage 12B may be communicated by providing a horizontal hole (a hole extending in the left-right direction in the drawings) in the plate 9.

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

[0029] The output rod 31 extends upward from the piston portion 33 to the outside of the cylinder body 2. The turning mechanism portion 32 turns the piston member 3 and the clamp arm 3A in accordance with the up and down movement of the piston member 3. The piston portion 33 fits into the inner periphery of the cylinder body 2. The auxiliary rod 34 extends downward from the piston portion 33. In other words, 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 fixed by a nut 3B.

[0031] The swivel mechanism 32 has a linear groove 32A and a swivel groove 32B formed on the outer circumferential surface of the piston member 3. A spherical body 6 held in the cylinder body 2 engages with the linear groove 32A and the swivel groove 32B. In the state shown in FIG. 1 , the spherical body 6 engages with the swivel groove 32B. The linear groove 32A extends in the vertical direction, and the swivel groove 32B extends spirally. The lower end of the linear groove 32A is continuous with the upper end of the swivel groove 32B. It is preferable that a plurality (for example, two or three) of the linear grooves 32A, the swivel grooves 32B, and the spherical bodies 6 be provided on the outer periphery 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 inside 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 up-and-down reciprocating motion.

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

[0034] The annular member 4 and the lower cylinder 5 are disposed below the cylinder body 2. A plurality of spheres 7 are provided in a circumferential arrangement on the outer periphery of the auxiliary rod 34. The spheres 7 move radially of the auxiliary rod 34 in conjunction with the up-and-down reciprocating motion of the auxiliary rod 34, thereby driving the valve member 8.

[0035] The valve member 8 switches between opening and closing 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 also communicates with the space below the plate 9. In other words, 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 swing clamp 100 with the piston member 3 at its lowermost position. In the state shown in Figure 2, the sphere 6 is engaged with the upper end of the rectilinear groove 32A. The clamp arm 3A has also been 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] Fig. 3 is an enlarged view of part III in Fig. 1. Fig. 4 is an enlarged view of part IV in Fig. 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 through holes 4A and 4B extending radially and a valve seat 4C. The through hole 4A communicates with the passage 11A, and the through hole 4B communicates with the passage 11B. The valve seat 4C is formed to extend horizontally. That is, the valve seat 4C is provided to extend in a plane direction intersecting (preferably substantially perpendicular to) the movement direction (up-down direction) of the valve member 8. The valve member 8 abuts against the valve seat 4C from above.

[0039] The lower cylinder 5 (inner peripheral member) includes a wall portion 5A and an accommodating hole 5B formed on the inner periphery of the wall portion 5A. A gap 5C is formed between the outer peripheral surface of the wall portion 5A and the inner peripheral surface of the annular member 4. The gap 5C connects the through holes 4A, 4B of the annular member 4. This allows the passages 11A, 11B of the fluid passage 11 to 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 with seal members. Therefore, the upper end face 8C of the valve member 8 faces the space in the cylinder chamber 2B where the working medium pressure acts, and the lower end face 8D of the valve member 8 is located midway along the fluid passage 11.

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

[0042] Passage 11B communicates with the external space. 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 increases, and when valve member 8 opens and passages 11A and 11B communicate, the pressure in passage 11A decreases. The state of valve member 8 can be detected by detecting the pressure change in passage 11A. It is also possible to supply pressurized air (fluid) to passage 11B to connect passage 11A to the external space.

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

[0044] When working medium pressure is supplied to the cylinder chamber 2A from the state shown in Fig. 3 and the piston member 3 is lowered, as shown in Fig. 4, the small diameter portion 34A of the auxiliary rod 34 is accommodated in the accommodation hole 5B of the lower cylinder 5, and the upper portion of the auxiliary rod 34 (the portion with a larger diameter than the small diameter portion 34A) abuts against the spherical body 7, pressing the spherical body 7 radially outward. At this time, the spherical body 7 abuts against the inclined surface 8B of the valve member 8, urging the valve member 8 upward. As a result, the end face 8D of the valve member 8 is separated from the valve seat 4C, the passages 11A and 11B of the fluid passage 11 are connected, and the air pressure in the passage 11A decreases.

[0045] However, in the present technology, the mechanism for detecting the position of the piston member 3 is not limited to detection based on the pressure change of the "compressed 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 a "decrease in flow rate" in the valve closed state and an "increase in flow rate" in the valve open state.

[0046] As described above, in the swing clamp 100 according to this embodiment, the valve member 8 is urged downward (in the valve closing direction) by utilizing the working medium pressure in the cylinder chamber 2B, and when the piston member 3 moves downward, the valve member 8 is moved upward (in the valve opening direction) via the auxiliary rod 34 and the sphere 7, thereby making it possible to detect the position of the piston member 3 including the output rod 31.

[0047] Furthermore, by adopting a poppet-type valve structure in which the end face 8D of the valve member 8 abuts against the valve seat 4C, the pressure difference between the closed and open states can be made more pronounced compared to a spool-type valve structure, thereby improving the accuracy of position detection. Furthermore, when simultaneously detecting the positions of multiple fluid pressure cylinders, even if the gaps in the valve structures of each individual fluid pressure cylinder are small, the cumulative total (total gap value) of these gaps tends to be large. In this regard, by adopting a poppet-type valve structure, the small gaps that occur in a spool-type valve structure can be eliminated (or minimized), thereby enabling accurate position detection even when simultaneously detecting the positions of multiple fluid pressure cylinders. However, the scope of the present technology is not limited to the poppet-type valve structure.

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

[0049] Furthermore, compared to when a valve body is provided on the inner periphery of the auxiliary rod, the diameter of the auxiliary rod 34 can be made smaller, which facilitates miniaturization in the radial direction.

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

[0051] Furthermore, in the swing clamp 100 according to the present embodiment, the valve member 8 is disposed so that the end surface 8C of the valve member 8 faces the space communicating with the cylinder chamber 2B. Therefore, there is no need to provide the auxiliary rod 34 with a seal member that separates the fluid passage 11 and the working medium passage 12, and the sliding resistance of the piston member 3 can be reduced.

[0052] In a fluid pressure cylinder that is miniaturized by reducing the piston diameter, the influence of sliding resistance tends to be greater. Reducing the sliding resistance of the piston member 3 is effective in a fluid pressure cylinder that is miniaturized (particularly in the radial direction). The swing clamp 100 according to this embodiment can promote miniaturization, particularly 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 a miniaturized fluid pressure cylinder.

[0053] The spheres 7 may be steel spheres, ceramic spheres, or spheres made of other materials. In the present technology, the shape of the engaging devices provided on the outer periphery of the auxiliary rod 34 is not limited to the spheres 7, and they may have shapes other than spheres (for example, pin shapes). It is preferable that the shapes of the multiple engaging devices lined up in the circumferential direction are substantially the same.

[0054] Second Embodiment Next, a swing clamp 100 according to a second embodiment will be described with reference to FIGS.

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

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

[0057] 7 (unclamped state), the auxiliary rod 34 abuts against the sphere 7, pressing the sphere 7 radially outward. At this time, the sphere 7 abuts against the inclined surface 8B of the valve member 8, urging the valve member 8 upward. The valve member 8 is driven upward against the urging force of the spring 10 and the downward force of the working medium pressure, and the end face 8D of the valve member 8 moves away from the valve seat 4C. As a result, passages 11A and 11B of the fluid passage 11 communicate with each other, and the air pressure in passage 11A decreases.

[0058] When working medium pressure is supplied to the cylinder chamber 2A from the state shown in Figure 7 and the piston member 3 is lowered, as shown in Figure 8, the large diameter portion of the auxiliary rod 34 is accommodated in the accommodation hole 5B of the lower cylinder 5, 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 is applied from the auxiliary rod 34 to the sphere 7. 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 downward. As a result, the end face 8D abuts against the valve seat 4C, closing the fluid passage 11 and increasing the air pressure in passage 11A.

[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), and when the piston member 3 moves upward, the valve member 8 is moved upward (in the valve opening direction) via the auxiliary rod 34 and the sphere 7, thereby making it possible to detect the position of the piston member 3 including the output rod 31.

[0060] When the piston member 3 passes the position shown in Figure 8 (clamped position) and further descends, the large diameter portion of the auxiliary rod 34 again abuts against the sphere 7, and the sphere 7 is pressed radially outward. This drives the valve member 8 upward, and the end face 8D of the valve member 8 moves away from the valve seat 4C. In other words, the valve member 8 switches to the open state, and the air pressure in the passage 11A decreases. By detecting this state, it is possible to detect the occurrence of a mis-clamped state.

[0061] Other points are the same as in the first embodiment, and therefore detailed description will not be repeated.

[0062] Third Embodiment Next, a swing clamp 100 according to a third embodiment will be described with reference to FIGS.

[0063] Fig. 9 is a cross-sectional view showing an unclamped state (clamped state), and Fig. 10 is an enlarged view of portion X in Fig. 9. Fig. 11 is a cross-sectional view showing a state in which the piston member 3 is mid-operation (state moving toward the clamped position), and Fig. 12 is an enlarged view of portion XII in Fig. 11. Fig. 13 is a cross-sectional view showing a clamped state (state in which the workpiece W is clamped), and Fig. 14 is an enlarged view of portion XIV in Fig. 13. Fig. 15 is a cross-sectional view showing a state in which the piston member 3 is at the lowering end (state having passed the clamped position), and Fig. 16 is an enlarged view of portion XVI in Fig. 15.

[0064] The swing clamp 100 according to this embodiment is a modified example of the swing clamp 100 according to the first and second embodiments, and switches between opening and closing using the end face 8D and outer peripheral surface 8E of the valve member 8, thereby realizing a completely closed state (first state), a completely open 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 abuts against the spherical body 7, pressing the spherical body 7 radially outward. At this time, the spherical body 7 abuts against the inclined surface 8B of the valve member 8, urging the valve member 8 upward. The valve member 8 is driven upward against the urging force of the spring 10 and the downward force of the working medium pressure, and the end face 8D of the valve member 8 moves away from the valve seat 4C. Meanwhile, the outer peripheral surface 8E of the valve member 8 is adjacent to the inner peripheral surface of the annular member 4 (outer peripheral member) via a slight gap (e.g., a gap width of approximately 0.01 mm to 0.05 mm). In other words, the valve member 8 closes the fluid passage 11 but is not completely closed, in an intermediate state (third state).

[0066] 9 and 10, when working medium pressure is supplied to the cylinder chamber 2A to lower the piston member 3, resulting in the state shown in FIGS. 11 and 12 (an intermediate operating state), the auxiliary rod 34, which has a diameter larger than the small-diameter portion 34A, abuts against the spherical body 7, which is further pressed radially outward, driving the valve member 8 further upward, and the outer peripheral surface 8E of the valve member 8 separates from the inner peripheral surface of the annular member 4 (the outer peripheral member). In other words, the valve member 8 switches to a fully open state (second state). As a result, the passages 11A and 11B of the fluid passage 11 are fully connected, and the air pressure in passage 11A decreases.

[0067] When the piston member 3 is further lowered from the state shown in FIGS. 11 and 12 to the state shown in FIGS. 13 and 14 (clamped state), the small-diameter portion 34B, which is even smaller than the small-diameter portion 34A, abuts the sphere 7. At this time, there is a slight gap between the small-diameter portion 34B and the sphere 7, and no radial force is applied to the sphere 7 from the auxiliary rod 34. In addition, the biasing force of the spring 10 acts on the end face 8C of the valve member 8, biasing the valve member 8 downward until the end face 8D abuts the valve seat 4C. In other words, 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 passage 11A increases.

[0068] 13 and 14, when the piston member 3 is further lowered to the state shown in FIGS. 15 and 16 (when the piston member 3 is at its lowermost position), the auxiliary rod 34, which has a diameter larger than the small-diameter portion 34A, again abuts against the spherical body 7, pressing the spherical body 7 radially outward. The valve member 8 is driven upward, and the end face 8D of the valve member 8 separates from the valve seat 4C. The outer peripheral surface 8E of the valve member 8 separates from the inner peripheral surface of the annular member 4 (outer peripheral member). In other words, the valve member 8 switches to a fully open state (second state). As a result, the passages 11A and 11B of the fluid passage 11 are fully connected, and the air pressure in passage 11A decreases.

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

[0070] 15 and 16 (where the piston member 3 is at the lowering end), i.e., where the piston member 3 has passed the clamped position, can be cited as an example of a state other than the clamped state and the unclamped state. By detecting the states shown in Figures 15 and 16, it is possible to detect that a mis-clamping operation has occurred.

[0071] Other points are the same as those in the first and second embodiments, and therefore detailed description 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 example of embodiments 1 to 3, and as shown in Figure 17, an engagement 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, lower cylinder 5, and plate 9 can be easily removed from the base 1 when removing the cylinder body 2 from the base 1.

[0073] As other points are the same as those in the first to third embodiments, detailed description will not be repeated.

[0074] (Embodiment 5) Fig. 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 modified example of embodiments 1 to 4, and as shown in Fig. 18, the present technology is applied to a link clamp 200 in which the clamp arm 3A does not pivot.

[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, hydraulic 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 urged downward (in the valve closing direction) by the hydraulic fluid pressure supplied to the cylinder chamber 2B.

[0076] In this embodiment, similarly to the first to fourth embodiments 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 the auxiliary rod 34 with a seal member that separates the fluid passage 11 from the working medium passage 12. This makes it possible to reduce the sliding resistance of the piston member 3.

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

[0078] In this way, with the link clamp 200 according to this embodiment, accurate position detection can be performed with a miniaturized fluid pressure cylinder while effectively suppressing a decrease in clamping force (achieving a clamping force equivalent to that in the absence of the auxiliary rod 34).

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

[0080] REFERENCE SIGNS LIST 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 engagement portion, 5 lower cylinder, 5A wall portion, 5B accommodation hole, 5C gap, 6, 7 sphere, 8 valve member, 8A cylindrical portion, 8B inclined surface, 8C end face, 8D end face, 8E outer circumferential surface, 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 portion, 32A linear groove, 32B swivel groove, 33 piston portion, 34 auxiliary rod, 34A, 34B small diameter portion, 100 swing clamp, 200 link clamp.

Claims

1. A fluid pressure cylinder comprising: a cylinder body; a piston member reciprocatable in a first direction relative to the cylinder body; a working medium chamber provided inside the cylinder body and supplied with a working medium for driving the piston member; a valve member provided facing 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 periphery 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, wherein the output rod and the auxiliary rod are coaxially arranged to extend in the first direction, and the valve member is provided on the outer periphery of the auxiliary rod and has a cylindrical portion extending in the first direction, wherein the opening and closing of the fluid passage by the valve member is switched in conjunction with the reciprocating movement of the auxiliary rod in the first direction, and the position of the piston member can be detected based on the open / closed state of the fluid passage.

2. A fluid pressure cylinder as set forth in claim 1, wherein the valve member has an end face at a tip opposite to the working medium chamber in the first direction, and further comprises a valve seat abutting against the end face from the first direction.

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

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

5. A fluid pressure cylinder as claimed in any one of claims 1 to 4, further comprising a plurality of spheres provided on the outer periphery of the auxiliary rod, wherein the valve member is driven in the first direction by the plurality of spheres moving in a direction intersecting the first direction in conjunction with the reciprocating movement of the auxiliary rod in the first direction, thereby switching between opening and closing the fluid passage by the valve member.

6. A fluid pressure cylinder according to any one of claims 2 to 4, further comprising an outer peripheral member provided on the outer periphery 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 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, and a third state in which the end face is spaced apart from the valve seat and the outer peripheral surface is close to the outer peripheral member.

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