Cylinder Device

Abstract

To suppress the entire length of a cylinder device.SOLUTION: A cylinder device 10 includes a first cylinder chamber 26 having a first piston 20, a second cylinder chamber 28 having a second piston 22, a first rod 46 connected to the first piston 20, a second rod 48 partially overlapped with the first rod 46 in a radial direction and protruding from a body 12, and a conversion mechanism 23 converting displacement of a part in an axial direction of the first rod 46 to displacement in a rotation direction of the second rod 48 and transmitting the displacement of another part in the axial direction of the first rod 46 as the displacement in the axial direction of the second rod 48. The second piston 22 is connected to the second rod 48.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cylinder device that displaces a rod in an axial direction and a rotational direction. [Background technology]

[0002] In automated factory lines, clamp cylinders (cylinder devices) are used to clamp objects. These cylinder devices clamp objects by using a rotating motion at the extrusion end of the rod and a linear axial motion toward the retraction end of the rod.

[0003] A cylinder device used in a clamp includes a conversion mechanism that converts the axial displacement of a piston into linear displacement of a rod and displacement in a rotational direction (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-227223 Summary of the Invention [Problem to be solved by the invention]

[0005] In some cases, it is necessary to increase the clamping force of a cylinder device to hold down an object. In such cases, a booster mechanism is used in which a booster piston is added to the cylinder device and the rod is driven by two pistons.

[0006] However, in conventional boosting mechanisms, the two pistons are driven with equal stroke lengths, which poses a problem of increasing the overall length of the cylinder device.

[0007] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0008] One aspect of the following disclosure is a cylinder device comprising: a first cylinder chamber having a first piston; a second cylinder chamber having a second piston; a first rod connected to the first piston; a second rod having a portion radially overlapping with the first rod and protruding from a body; and a conversion mechanism that converts a portion of the axial displacement of the first rod into a rotational displacement of the second rod and transmits another portion of the axial displacement of the first rod as an axial displacement of the second rod, wherein the second piston is connected to the second rod. [Effects of the Invention]

[0009] In the cylinder device from the above viewpoint, the stroke length of the second piston can be restricted to the stroke range of the second rod, and therefore the overall length of the cylinder device can be restricted. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of a cylinder device according to a first embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the cylinder device of FIG. [Figure 3] Figure 3A is an explanatory diagram showing the positional relationship between the first rod, second rod, first pin groove, and second pin groove of the cylinder device of Figure 1, and Figure 3B is a schematic diagram showing the positional relationship between the displacement switching groove and rotation groove of the second rod, the support pin, and the link pin expanded on a plane. [Figure 4] Figure 4A is a cross-sectional view of the cylinder device of Figure 1 when the rod is positioned at the extrusion end (extrusion end position), and Figure 4B is a schematic diagram showing the position of the support pin in the displacement switching groove and the position of the link pin in the rotation groove in the state of Figure 4A. [Figure 5] 5A is a cross-sectional view of the cylinder device of FIG. 1 in a state where rotation of the rod has finished (rotation end position), and FIG. 5B is a schematic diagram showing the position of the support pin in the displacement switching groove and the position of the link pin in the rotation groove in the state of FIG. 5A. [Figure 6]6A is a cross-sectional view of the cylinder device of FIG. 1 in a state where the rod is at the retracted end (retracted end position), and FIG. 6B is a schematic diagram showing the position of the support pin in the displacement switching groove and the position of the link pin in the rotation groove in the state of FIG. 6A. [Figure 7] FIG. 7A is a cross-sectional view of a cylinder device according to a first modified example of the first embodiment, and FIG. 7B is a cross-sectional view of a cylinder device according to a second modified example of the first embodiment. [Figure 8] FIG. 8 is a perspective view of a body according to a third modified example of the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view of a cylinder device according to the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a cylinder device according to a modified example of the second embodiment. [Figure 11] FIG. 11A is a cross-sectional view of a cylinder device according to a third embodiment, and FIG. 11B is a cross-sectional view of the cylinder device of FIG. 11A at a rotation end position. [Figure 12] FIG. 12A is a cross-sectional view of a cylinder device according to a first modified example of the third embodiment, and FIG. 12B is a cross-sectional view of a cylinder device according to a second modified example of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (First embodiment) The cylinder device 10 according to this embodiment shown in FIG. 1 is a clamp cylinder. The cylinder device 10 is used, for example, in an automated line to secure a workpiece to be machined. The cylinder device 10 includes a rod 14 protruding from a body 12. The rod 14 pivots at the extrusion end (unclamped end) and, after pivoting, linearly displaces toward the retracted end (clamped end). In this specification, the extension direction of the rod 14 is also referred to as the axial direction. In addition, in the axial direction, the direction toward the retracted end is also referred to as the first direction, and the direction toward the extrusion end is also referred to as the second direction.

[0012] As shown in FIGS. 1 and 2, the cylinder device 10 includes a body 12 (cylinder tube), a rod 14, a rod cover 16, a partition member 18, a first piston 20, a second piston 22, and a conversion mechanism 23.

[0013] The body 12 is a cylindrical member having a rectangular parallelepiped outer shape. The body 12 has a cylinder chamber 24 therein that has a circular cross section. The cylinder chamber 24 extends in the axial direction. As shown in FIG. 1 , the cylinder chamber 24 is divided by a partition member 18 into a first cylinder chamber 26 and a second cylinder chamber 28. The end of the cylinder chamber 24 in the first direction is closed by an end wall 30 of the body 12. The body 12 is formed of a material such as metal or resin.

[0014] 2, the body 12 has a first body 12a positioned closer to the first direction and a second body 12b positioned closer to the second axial direction. The first body 12a and the second body 12b are axially connected by a fastening rod 31 (tie rod). The first body 12a has a first cylinder chamber 26 therein. The end of the first cylinder chamber 26 in the first direction is closed by an end wall 30 of the first body 12a.

[0015] The first body 12a has a first fluid supply / discharge portion 32 and a second fluid supply / discharge portion 34 for supplying and discharging fluid to and from the first cylinder chamber 26. The first fluid supply / discharge portion 32 opens at or near the first direction end of the first cylinder chamber 26. The first fluid supply / discharge portion 32 supplies and discharges pressurized fluid to and from the empty chamber 26a on the first direction side of the first cylinder chamber 26 via external piping. The second fluid supply / discharge portion 34 opens at or near the second direction end of the first cylinder chamber 26. The second fluid supply / discharge portion 34 supplies and discharges pressurized fluid to and from the empty chamber 26b on the second direction side of the first cylinder chamber 26 via external piping.

[0016] A first connection flow path 36a branches off and extends from the second fluid supply / discharge portion 34. The first connection flow path 36a is a flow path formed inside the first body 12a and extends in the second direction. The first connection flow path 36a communicates with a second connection flow path 36b in the second body 12b at the end of the first body 12a in the second direction.

[0017] As shown in Fig. 2, the second body 12b has a through hole 24a that constitutes part of the cylinder chamber 24. As shown in Fig. 1, the through hole 24a has an end in the first direction that is blocked by a partition member 18, and an end in the second direction that is blocked by a rod cover 16. A second cylinder chamber 28 is formed between the partition member 18 and the rod cover 16. Furthermore, the second body 12b has a first port 38 and a second port 40 that communicate with the second cylinder chamber 28, and a second connection flow path 36b. The first connection flow path 36a and the second connection flow path 36b constitute a connection flow path 36 that supplies and discharges fluid to and from the second cylinder chamber 28.

[0018] The second connection passage 36b is a passage that extends axially inside the second body 12b. The first end of the second connection passage 36b is connected to the first connection passage 36a. The second end of the second connection passage 36b is connected to the second port 40.

[0019] The first port 38 opens at or near the first-direction end of the second cylinder chamber 28. In this embodiment, the first port 38 is a breathing hole that communicates with the outside and maintains the empty chamber 28a on the first-direction side of the second piston 22 at atmospheric pressure. The second port 40 communicates with the second fluid supply / discharge unit 34 through the connection flow path 36 (the first connection flow path 36a and the second connection flow path 36b). The second port 40 opens at or near the second-direction end of the second cylinder chamber 28. The second port 40 supplies and discharges pressurized fluid to and from the empty chamber 28b on the second-direction side of the second piston 22 through the second fluid supply / discharge unit 34.

[0020] The second cylinder chamber 28 has an expanded diameter portion 42 near its end in the second direction. The expanded diameter portion 42 has a groove shape that extends around the entire circumferential direction of the second cylinder chamber 28. The inner diameter of the expanded diameter portion 42 is larger than the outer diameters of the second piston 22 and the packing 22a. The expanded diameter portion 42 is located on the outer periphery of the second piston 22 when the second piston 22 is located at the stroke end (extension end position) in the second direction. The expanded diameter portion 42 is spaced apart from the second piston 22 at the stroke end (extension end position) in the second direction. The gap between the expanded diameter portion 42 and the second piston 22 forms a leak flow path 44 that allows the pressurized fluid from the second port 40 to leak toward the void chamber 28a (see FIG. 5A). The expanded diameter portion 42 communicates with the void chambers 28a and 28b on both sides of the second piston 22 at the extrusion end position of the second piston 22.

[0021] As shown in FIG. 1, the rod cover 16 has a T-shaped cross section. The rod cover 16 has a cover hole 16a in the center. The rod 14 (second rod 48) is inserted into the cover hole 16a. The cover hole 16a supports the second rod 48 so that it can be displaced in the axial and rotational directions. The rod cover 16 further has a rod bushing 16b and a rod packing 16c. The rod bushing 16b is disposed in the cover hole 16a. The rod bushing 16b slides against the outer peripheral surface of the rod 14 to guide the displacement of the rod 14 along the axial direction. The rod packing 16c prevents fluid leakage along the cover hole 16a.

[0022] 2, the partition member 18 is a cylindrical member, and has an outer peripheral surface 18a on its outer periphery that is in close contact with the cylinder chamber 24. The partition member 18 is fixed to the body 12 by a set screw (not shown) so that it cannot be displaced in the axial or rotational directions.

[0023] As shown in FIG. 1 , the partition member 18 has a through-hole 45 penetrating through its center in the axial direction. The through-hole 45 has a partition hole 45a and an accommodating hole 45b. The partition hole 45a is located on the first direction side and has an inner diameter equal to or slightly larger than that of the first rod 46. The partition hole 45a allows the first rod 46 to be inserted therethrough so as to be displaceable in the axial direction. A packing is provided in the partition hole 45a to prevent leakage of fluid along the outer peripheral surface of the first rod 46. The accommodating hole 45b is located on the second direction side of the partition hole 45a and is connected to the partition hole 45a. The accommodating hole 45b has an inner diameter larger than that of the partition hole 45a. The accommodating hole 45b has an inner diameter large enough to accommodate the second rod 48 so as to be displaceable in the axial direction. The second end of the accommodating hole 45b opens toward the second cylinder chamber 28.

[0024] The partition member 18 has a retaining hole 18b located near the end of the partition member 18 in the second direction. The retaining hole 18b is a hole that radially penetrates the partition member 18 and holds a support pin 56. The support pin 56 is formed as a cylindrical rod that extends radially, perpendicular to the axial direction. The partition member 18 holds the support pin 56 relative to the body 12 so that it cannot be displaced in the rotational and axial directions.

[0025] The first piston 20 is disposed in the first cylinder chamber 26. The first piston 20 has a packing 20a on its outer periphery, which divides the first cylinder chamber 26 into a first-direction chamber 26a and a second-direction chamber 26b. The first piston 20 is displaced axially along the first cylinder chamber 26 due to the pressure difference between the chambers 26a and 26b.

[0026] The second piston 22 is disposed in the second cylinder chamber 28. The second piston 22 has a packing 22a on its outer periphery. The second piston 22 is displaced in the axial direction along the second cylinder chamber 28. A rod 14 is connected to the first piston 20 and the second piston 22.

[0027] The rod 14 includes a first rod 46 and a second rod 48. The first rod 46 is disposed along the central axis of the body 12, and its end in the first direction is connected to the first piston 20. The first rod 46 displaces together with the first piston 20. The first rod 46 extends in the second direction from the first piston 20. The first rod 46 passes through a partition wall hole 45a in the partition wall member 18 and extends toward the second cylinder chamber 28. A portion of the first rod 46 is housed in an axial hole 60 in a cylindrical portion 48b of the second rod 48. The first rod 46 radially overlaps with the second rod 48. The first rod 46 may radially overlap from the outer periphery of the second rod 48. The first rod 46 has a first pin groove 52 and a pin hole 54 at the overlapping portion with the second rod 48.

[0028] As shown in FIGS. 1 and 2, the first pin groove 52 penetrates the first rod 46 in a radial direction perpendicular to the axial direction. When viewed from the side, the first pin groove 52 extends axially like a slit. The axial length of the first pin groove 52 is set to be equal to or greater than the stroke length of the first piston 20. As shown in FIG. 1, a support pin 56 supported by the partition member 18 is inserted into the first pin groove 52. The support pin 56 is fixed to the body 12 in the axial and rotational directions. Therefore, the support pin 56 and the first pin groove 52 restrict displacement of the first rod 46 in the rotational direction, and the first rod 46 is only displaceable in the axial direction.

[0029] The pin hole 54 is located away from the first pin groove 52 on the first direction side. The pin hole 54 penetrates the first rod 46 in the radial direction. A link pin 58 is inserted through the pin hole 54. The penetrating direction of the pin hole 54 is shifted by 90° in the circumferential direction from the penetrating direction of the first pin groove 52. Therefore, the link pin 58 is inserted through the pin hole 54 in a direction perpendicular to the support pin 56.

[0030] The second rod 48 is disposed on the second direction side of the first rod 46. The second rod 48 is disposed along the axial direction of the body 12 and passes through the second cylinder chamber 28 in the axial direction. The second rod 48 has a rod portion 48a that protrudes from the body 12 and a cylindrical portion 48b that is located on the first direction side of the rod portion 48a. The rod portion 48a is inserted through the cover hole 16a of the rod cover 16. The rod portion 48a protrudes from the rod cover 16.

[0031] The cylindrical portion 48b is located on the first direction side of the rod portion 48a. The cylindrical portion 48b is a cylindrical portion with a larger diameter than the rod portion 48a. The cylindrical portion 48b has an axial hole 60 with a circular cross section inside. The axial hole 60 extends in the axial direction and opens at an end in the first direction. The axial hole 60 accommodates the first rod 46 so that it can be displaced in the axial direction. A second piston 22 is connected to the cylindrical portion 48b. In this embodiment, the second piston 22 and the second rod 48 are formed integrally and are connected, and the second piston 22 cannot be displaced in the rotational direction relative to the second rod 48.

[0032] As shown in Fig. 3A, the cylindrical portion 48b has a displacement switching groove 62 through which the support pin 56 is inserted, and a rotation groove 64 through which the link pin 58 is inserted. The displacement switching groove 62 and the rotation groove 64 extend radially from the outer circumferential surface of the cylindrical portion 48b to the shaft hole 60. As shown in Fig. 3B, two displacement switching grooves 62 are provided circumferentially at intervals of 180°. Two rotation grooves 64 are also provided circumferentially at intervals of 180°.

[0033] The displacement switching groove 62 has an axial portion 62a extending in the axial direction and a circumferential portion 62b extending in the circumferential direction from the end of the axial portion 62a in the first direction. That is, the displacement switching groove 62 has an L-shape in side view. The axial length L1 of the axial portion 62a is set to, for example, half the stroke length of the first piston 20. The circumferential portion 62b extends within an angular range of a rotation angle (for example, 90°) required for the orbital motion of the second rod 48.

[0034] The rotational groove 64 extends at a predetermined angle relative to the axial direction. The axial length L2 of the rotational groove 64 is set to half the stroke length of the first piston 20. The circumferential angular range of the rotational groove 64 extends within the angular range of the rotation angle required for the orbital motion of the second rod 48. In other words, the circumferential angular range of the rotational groove 64 is the same as the angular range of the circumferential portion 62b of the displacement switching groove 62. However, the rotational groove 64 is positioned circumferentially offset by 90° from the circumferential portion 62b. Furthermore, the rotational groove 64 is positioned spaced apart in the first direction from the displacement switching groove 62.

[0035] The conversion mechanism 23 is composed of a support pin 56, a link pin 58, a displacement switching groove 62, and a rotation groove 64. The support pin 56 is not displaceable in the axial direction or rotation direction relative to the body 12. The support pin 56 is inserted into the displacement switching groove 62. The link pin 58 is displaceable in the axial direction relative to the body 12, but is not displaceable in the rotation direction. The link pin 58 is inserted into the rotation groove 64.

[0036] The displacement switching groove 62 and the rotation groove 64, together with the second rod 48, are displaced in the axial direction and the rotational direction relative to the body 12. The displacement switching groove 62 and the rotation groove 64 convert a portion of the axial displacement of the link pin 58 into a rotational displacement of the second rod 48. The displacement switching groove 62 and the rotation groove 64 also convert another portion of the axial displacement of the link pin 58 into an axial displacement of the second rod 48.

[0037] When the first piston 20 is located at the end in the first direction (retracted end position), the support pin 56 and the link pin 58 are positioned as shown in Fig. 3B. That is, the support pin 56 is located at the end in the second direction of the axial portion 62a, and the link pin 58 is located at the end in the first direction of the rotation groove 64.

[0038] The cylinder device 10 of this embodiment is configured as described above, and its operation will be described below.

[0039] The cylinder device 10 performs a return operation from the retracted end position shown in Fig. 1 to the extrusion end position shown in Fig. 4A. The return operation is performed by connecting the first fluid supply / discharge unit 32 to a pressurized fluid source 66 and connecting the second fluid supply / discharge unit 34 to an exhaust unit 68. This drives the first piston 20 in the second direction, and the first piston 20 stops at the end of the first cylinder chamber 26 in the second direction. The second rod 48 is driven in the second direction by the first rod 46, and the second piston 22 is positioned at the end of the second cylinder chamber 28 in the second direction (extrusion end position).

[0040] At the extrusion end position, the second rod 48 protrudes in the second direction and is rotated 90° circumferentially from the state shown in FIG. 1. As shown in FIG. 4B, the support pin 56 is located at the end of the circumferential portion 62b of the displacement switching groove 62. The link pin 58 is located at the end of the rotation groove 64 in the second direction. The second piston 22 is located in the expanded diameter portion 42 of the second cylinder chamber 28.

[0041] Next, the second rod 48 of the cylinder device 10 is clamped. The clamping operation includes a pivoting motion of the rod 14 at the extrusion end and a linear retraction motion of the rod 14 toward the retraction end. As shown in FIG. 5A, the clamping operation is performed by connecting the exhaust unit 68 to the first fluid supply / discharge unit 32 through the motion selector valve 70 and connecting the pressurized fluid source 66 to the second fluid supply / discharge unit 34. Pressurized fluid is supplied to the empty chamber 26b of the first cylinder chamber 26 through the second fluid supply / discharge unit 34, displacing the first piston 20 in the first direction. The first rod 46 is displaced in the first direction together with the first piston 20.

[0042] As a result, the first piston 20 moves from the extrusion end position shown in FIG. 4A to the state shown in FIG. 5A (rotation end position). During this time, the second rod 48 undergoes a rotational displacement (pivoting motion). As shown in FIG. 5B, the displacement of the first rod 46 in the first direction causes the link pin 58 to move in the first direction. Because the circumferential position of the link pin 58 is constant, the rotation groove 64 rotates to follow the link pin 58 as the link pin 58 moves in the first direction. As a result, the entire second rod 48 rotates -90° in the circumferential direction, causing the rod 14 to pivot. Note that the axial displacement of the second rod 48 is prevented by the support pin 56 located in the circumferential portion 62b. Therefore, the second rod 48 and the second piston 22 continue to rotate while remaining at the end in the second direction until the support pin 56 moves to the axial portion 62a.

[0043] As the second rod 48 rotates, the second piston 22 rotates with the second rod 48. In this embodiment, the rotation of the second piston 22 is performed by the expanded diameter portion 42. The expanded diameter portion 42 reduces frictional resistance during rotation between the second piston 22 and its packing 22a. Therefore, the second rod 48 can rotate with less force. Therefore, the expanded diameter portion 42 reduces wear between the link pin 58 and the rotation groove 64, which generates the rotational movement.

[0044] 5A, the expanded diameter portion 42 forms a leak passage 44 between itself and the outer periphery of the second piston 22, which allows the fluid in the second port 40 to escape toward the void chamber 28a. The leak passage 44 prevents the generation of a driving force for the second piston 22 while the second piston 22 is rotating. Therefore, the expanded diameter portion 42 prevents the generation of an increased pressure during the rotation of the second piston 22, thereby preventing wear between the support pin 56 and the circumferential portion 62b. By providing such an expanded diameter portion 42, wear on the conversion mechanism 23 can be prevented, and the life of the cylinder device 10 can be extended.

[0045] Next, the rod 14 of the cylinder device 10 undergoes a linear retraction motion. As shown in FIG. 6A, during this motion, the second rod 48 is displaced in the first direction together with the first rod 46. As shown in FIG. 6B, the displacement of the first rod 46 in the first direction is transmitted to the second rod 48 via the link pin 58 and the rotation groove 64. Furthermore, because the support pin 56 is located in the axial portion 62a of the displacement switching groove 62, it does not impede the axial displacement of the second rod 48. Therefore, the second rod 48 begins to be displaced so as to be retracted in the first direction.

[0046] When the second rod 48 is displaced a predetermined distance in the first direction, the packing 22a of the second piston 22 moves over the enlarged diameter portion 42 and toward the first direction side of the enlarged diameter portion 42. As a result, the second piston 22 separates the second cylinder chamber 28 in a liquid-tight and airtight manner. The fluid flowing in from the second port 40 increases the pressure in the empty chamber 28b to be greater than the pressure in the empty chamber 28a, and a driving force in the first direction is generated in the second piston 22. As a result, the second rod 48 is displaced so as to be pulled in the first direction by the driving forces of the first piston 20 and the second piston 22. At that time, the rod 14 generates a larger driving force.

[0047] In the cylinder device 10 of the present embodiment as described above, the second piston 22 is connected to the second rod 48, so the stroke range of the second piston 22 is limited to the stroke range of the second rod 48. Therefore, in this embodiment, the axial length of the second cylinder chamber 28 that houses the second rod 48 can be short, and the overall length of the cylinder device 10 can be shorter than when the second piston 22 is connected to the first rod 46.

[0048] (First Modification of the First Embodiment) 7A shows the second cylinder chamber 28 and the second piston 22 at the extrusion end position of the cylinder device 10 according to the first modified example. In this modified example, at the extrusion end position, the opening of the second port 40 of the second cylinder chamber 28 is positioned more toward the first direction than the second port 40 shown in FIGS. 1 to 6B. The second port 40 positioned in this manner prevents the second piston 22 from receiving a boosting driving force during rotational displacement of the rod 14, thereby preventing wear on the displacement switching groove 62.

[0049] In this modification, a V-packing is preferably used as the packing 22a of the second piston 22. The V-packing is arranged so that the tip of the V faces the first direction. The V-packing remains closed until pressure is applied to the chamber 28b on the second direction side, so frictional resistance during rotation of the second piston 22 can be suppressed even without providing the expanded diameter portion 42. Therefore, in this modification, the second cylinder chamber 28 does not need to be provided with the expanded diameter portion 42.

[0050] In this modified example, when the packing 22a of the second piston 22 is displaced toward the first direction relative to the second port 40, a driving force toward the first direction can be generated in the second piston 22. The cylinder device 10 of this modified example does not require the expanded diameter portion 42, and therefore the structure is simplified.

[0051] (Second Modification of the First Embodiment) 7B differs from the first modified example (FIG. 7A) in the position of the second port 40. In this modified example, the second port 40 is located slightly toward the first direction from the top of the outer circumferential side of the packing 22a. In this modified example, the gap between the packing 22a and the second cylinder chamber 28 serves as a leak flow path 44, preventing the generation of increased pressure when the second piston 22 rotates.

[0052] (Third modified example of the first embodiment) As shown in FIG. 8 , the cylinder device 10 of this modified example has an axial groove 72 in the inner circumferential surface of the second cylinder chamber 28 that communicates with the expanded diameter portion 42. The axial groove 72 forms a leak flow path 44 that allows fluid from the second port 40 to leak when the second piston 22 is located at the extrusion end position. The cylinder device 10 of this modified example can prevent the generation of increased pressure during the rotational movement of the second piston 22. Note that the illustrated example shows an example in which the expanded diameter portion 42 and the axial groove 72 are provided, but this modified example is not limited to this. The expanded diameter portion 42 may not be provided, and the axial groove 72 may be provided to communicate with the second port 40.

[0053] (Second embodiment) The cylinder device 10A of this embodiment shown in Figure 9 differs from the cylinder device 10 of Figure 1 in that it is equipped with a second piston 22A that is rotatable relative to a second rod 48. In the cylinder device 10A of Figure 9, the same components as those in the cylinder device 10 of Figure 1 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0054] The second piston 22A has a mounting hole 74 in its center, through which the second rod 48 can be inserted. The mounting hole 74 passes axially through the second piston 22A. The mounting hole 74 has a packing mounting groove 76 and a stopper mounting groove 78 on its inner periphery. The packing mounting groove 76 is formed near the axial center of the mounting hole 74 and accommodates a packing 80. The packing 80 prevents fluid leakage along the gap between the inner periphery of the second piston 22A and the cylindrical portion 48b.

[0055] The stopper mounting groove 78 is located at the end of the second piston 22A in the second direction. The stopper mounting groove 78 accommodates a ring-shaped stopper 82 and a fastener 84. The stopper 82 and the fastener 84 engage with an engagement groove 86 formed on the outer peripheral surface of the second rod 48. The stopper 82 and the fastener 84 prevent axial displacement of the second piston 22A relative to the second rod 48.

[0056] The second piston 22A of this embodiment is rotatable relative to the second rod 48, and does not follow the rotational displacement of the second rod 48 at the extrusion end position. Therefore, the expanded diameter portion 42 (see FIG. 1) is not required on the inner circumferential surface of the second cylinder chamber 28. The cylinder device 10A of this embodiment can prevent wear between the link pin 58 and the rotation groove 64 without providing the expanded diameter portion 42, and the structure can be simplified.

[0057] (Modification of the second embodiment) As shown in Fig. 10, this modified example includes the second piston 22A shown in Fig. 9. The second piston 22A of this modified example has a first packing 88 and a second packing 90 arranged on the outer periphery, the first packing 88 being spaced apart in the axial direction. As shown in the figure, when the second piston 22A is positioned at the stroke end in the second direction (extrusion end position), the first packing 88 is arranged between the second port 40 and the empty chamber 28a, and the second packing 90 is arranged between the second port 40 and the empty chamber 28b.

[0058] When the second rod 48 undergoes rotational displacement, the first packing 88 prevents leakage of fluid into the chamber 28a, and the second packing 90 prevents leakage of fluid into the chamber 28b, thereby preventing the generation of a boosting driving force.

[0059] Therefore, the cylinder device 10A of this modified example can suppress the amount of fluid consumed by preventing leakage of the fluid through the second cylinder chamber 28, thereby reducing energy consumption.

[0060] (Third embodiment) In the cylinder device 10B of this embodiment shown in Figures 11A and 11B, the second port 40B opens into the cover hole 16a of the rod cover 16B. Note that in the cylinder device 10B of Figures 11A and 11B, the same components as those in the cylinder device 10A of Figure 9 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0061] As shown in Fig. 11A, the cylinder device 10B has a rod cover 16B and a rotary valve 92. The rod cover 16B has a second port 40B and a cover passage 94. The cover passage 94 is a portion where the inner diameter of the cover hole 16a is enlarged, and is located on the first direction side of the cover hole 16a. The inner diameter of the cover passage 94 is larger than the outer diameter of the cylindrical portion 48b of the second rod 48. The end of the cover passage 94 on the first direction side opens toward the second cylinder chamber 28 (void chamber 28b).

[0062] The second port 40B is formed as a radially extending flow passage formed inside the rod cover 16B. The second port 40B is arranged at a predetermined circumferential position of the body 12. The inner circumferential end of the second port 40B opens to the inner circumferential surface of the cover flow passage 94. The rod cover 16B has a circumferential groove 41 on its outer periphery. The circumferential groove 41 is arranged at a position facing one end of the connection flow passage 36 and communicates with the connection flow passage 36. The circumferential groove 41 extends around the entire circumferential circumference of the rod cover 16B. The second port 40B communicates with the connection flow passage 36 via the circumferential groove 41.

[0063] The rotary valve 92 is a cylindrical member attached to the cylindrical portion 48b of the second rod 48. The rotary valve 92 is located at the end of the cylindrical portion 48b in the second direction and is attached to the outer periphery of the cylindrical portion 48b. The rotary valve 92 moves in the rotational and axial directions integrally with the second rod 48. When the second rod 48 is located at the extrusion end position, the rotary valve 92 is housed in the cover flow path 94. The rotary valve 92 comes into close contact with the inner circumferential surface of the cover flow path 94, blocking communication between the second port 40B and the second cylinder chamber 28.

[0064] As shown in FIG. 11B, the rotary valve 92 has a communication groove 96 extending in the axial direction at a predetermined circumferential position. The communication groove 96 of the rotary valve 92 is disposed at a circumferential position that coincides with the second port 40B when the second rod 48 is in the rotation end position. When the rod 14 is in the extrusion end position, the rotary valve 92 seals the cover flow path 94 as shown in FIG. 11A. When the rotation of the rod 14 ends, the rotary valve 92 rotates in the direction shown in FIG. 11B. As shown in the figure, when the rotation end position is reached, the second port 40B and the empty chamber 28b of the second cylinder chamber 28 are in communication with each other through the communication groove 96.

[0065] Therefore, the cylinder device 10B of this embodiment can prevent the second piston 22A from increasing in force during the rotational movement of the rod 14, and can prevent wear between the displacement switching groove 62 and the support pin 56.

[0066] (First modified example of the third embodiment) 12A, the cylinder device 10B of this modified example includes a second rod 48 having a step portion 98 instead of the rotary valve 92, and a rod cover 16B having a cover flow path 94 that is closed by the second rod 48. Note that a description of the same configuration as the cylinder device 10B of FIG. 11A will be omitted.

[0067] 12A, the rod cover 16B has a cover flow passage 94 and a second port 40B that opens into the cover flow passage 94. A packing accommodating groove 94a is formed in the cover flow passage 94 on the first direction side of the opening of the second port 40B. A sealing gasket 100 is attached to the packing accommodating groove 94a.

[0068] The second rod 48 is provided with a step 98. The first direction side of the step 98 is a large diameter portion 98a, which is connected to the cylindrical portion 48b. The large diameter portion 98a has a diameter slightly smaller than that of the cover flow passage 94. At the extrusion end position of the rod 14, the large diameter portion 98a is inserted into the cover flow passage 94. The outer peripheral surface of the large diameter portion 98a is in close contact with a sealing gasket 100, preventing communication between the second port 40B and the second cylinder chamber 28.

[0069] The second rod 48 has a small diameter portion 98b on the second direction side of the step portion 98. The small diameter portion 98b has an outer diameter that is sufficiently smaller than the inner diameter of the sealing packing 100. When the second rod 48 is retracted and the step portion 98 moves toward the first direction side of the cover flow passage 94, the small diameter portion 98b forms a flow passage between the cover flow passage 94 and the small diameter portion 98b, through which a fluid can flow.

[0070] 12A, the fluid in the second port 40B is sealed by the sealing packing 100 and the large diameter portion 98a. Therefore, the second piston 22A does not generate a driving force for boosting the force during the rotation of the rod 14. Therefore, the cylinder device 10B of this modified example can prevent wear between the displacement switching groove 62 and the support pin 56.

[0071] Furthermore, when the rotational displacement of the second rod 48 ends and the second rod 48 displaces in the first direction, the step portion 98 moves toward the first direction beyond the cover flow path 94. As a result, the second port 40B and the empty chamber 28b of the second cylinder chamber 28 communicate with each other, and fluid is supplied to the empty chamber 28b. A driving force for boosting the force can be generated in the second piston 22A.

[0072] (Second modified example of the third embodiment) The cylinder device 10B of this modified example differs from the cylinder device 10B of Fig. 12A in that the sealing gasket 100 is arranged on the large diameter portion 98a side. In other respects, it is the same as the cylinder device 10B of Fig. 12A. In this modified example, when the large diameter portion 98a of the second rod 48 moves toward the first direction side beyond the cover flow path 94, fluid is supplied to the second cylinder chamber 28, and the second piston 22A generates a driving force for boosting.

[0073] The cylinder device 10B of this modified example has the same effects as the cylinder device 10B of FIG. 12A.

[0074] The above disclosure can be summarized as follows:

[0075] One aspect is a cylinder device comprising: a first cylinder chamber having a first piston; a second cylinder chamber having a second piston; a first rod connected to the first piston; a second rod having a portion radially overlapping with the first rod and protruding from a body; and a conversion mechanism that converts a portion of the axial displacement of the first rod into a rotational displacement of the second rod and transmits another portion of the axial displacement of the first rod as an axial displacement of the second rod, wherein the second piston is connected to the second rod.

[0076] In the cylinder device described above, the stroke length of the second piston can be shortened, so the overall length of the second cylinder chamber can be reduced, and the overall length of the cylinder device can be shortened.

[0077] In the cylinder device described above, the conversion mechanism may be located between the first piston and the second piston. In this cylinder device, the second piston is located at a position that is not affected by the stroke of the first piston, so the stroke length of the second piston can be shortened.

[0078] In the above-described cylinder device, the axial length of the second cylinder chamber may be shorter than the axial length of the first cylinder chamber, thereby enabling the cylinder device to have a reduced axial dimension.

[0079] In the above-described cylinder device, the second cylinder chamber may have an inner diameter larger than that of the second piston and may have an expanded diameter portion that separates the second piston at the extrusion end position from the inner circumferential surface of the second cylinder chamber. This cylinder device can suppress wear of the conversion mechanism by suppressing sliding resistance during rotational displacement of the second piston.

[0080] In the above-described cylinder device, the expanded diameter portion may communicate with chambers on both axial sides of the second piston at the extrusion end position. This cylinder device can prevent a boosting driving force from being generated in the second piston when the second piston is rotationally displaced, and can prevent wear on the conversion mechanism.

[0081] The cylinder device may have a first port that opens to an end of the second cylinder chamber in a first direction toward a retraction end position, and a second port that opens to an end of the second cylinder chamber in a second direction toward a push-out end position. This cylinder device can drive the second piston by supplying and discharging fluid between the first port and the second port.

[0082] In the above-described cylinder device, the second port may open into the second cylinder chamber at a position shifted in the first direction from a packing of the second piston at the extrusion end position. This cylinder device can prevent a boosting driving force from being generated in the second piston when the second piston is rotationally displaced, and can prevent wear of the conversion mechanism.

[0083] In the above-described cylinder device, the second cylinder chamber may have a leak flow path on an inner circumferential surface thereof that allows the fluid supplied from the second port to escape toward the first direction beyond the second piston. This cylinder device can prevent a boosting driving force from being generated in the second piston when the second piston is rotationally displaced, and can prevent wear of the conversion mechanism.

[0084] In the above-described cylinder device, the leak passage may be a groove formed on the inner peripheral surface of the second cylinder chamber and extending in the axial direction. This cylinder device can prevent a boosting driving force from being generated in the second piston when the second piston is rotationally displaced, and can prevent wear of the conversion mechanism.

[0085] The cylinder device may include a first fluid supply / discharge portion that opens to the first direction side of the first cylinder chamber and a second fluid supply / discharge portion that opens to the second direction side of the first cylinder chamber, and the body may have a connecting flow path that connects the second fluid supply / discharge portion to the second port. Since this cylinder device can supply and discharge fluid to the second port through the second fluid supply / discharge portion, the number of connected pipes can be reduced.

[0086] The cylinder device may include a first packing provided on an outer periphery of the second piston and positioned closer to the first direction than the second port at the extrusion end position of the second piston, and a second packing provided on the outer periphery of the second piston and positioned closer to the second direction than the second port at the extrusion end position of the second piston. This cylinder device can prevent fluid leakage at the extrusion end and reduce consumption of pressurized fluid.

[0087] The cylinder device may further include a rod cover having a cover hole through which the second rod is inserted, a cover passage formed by a gap between the cover hole and the second rod and fluidly connecting the second port and the second cylinder chamber, and a sealing packing that closes the cover passage at the stroke end of the second rod in the second direction and opens the cover passage and the second cylinder chamber when the second rod moves in the first direction. This cylinder device can prevent fluid leakage at the extrusion end and reduce consumption of pressurized fluid.

[0088] The cylinder device may further include a rod cover having a cover hole through which the second rod is inserted, a cover passage formed by a gap between the cover hole and the second rod and fluidly connecting the second port and the second cylinder chamber, and a rotary valve disposed in the cover passage, rotating together with the second rod, and opening the cover passage when the second rod is positioned at a predetermined angle. This cylinder device can prevent fluid leakage at the extrusion end and reduce consumption of pressurized fluid.

[0089] In the above-described cylinder device, the second piston may be rotatably connected to the second rod. This cylinder device requires less sliding resistance to the rotational displacement of the second rod, thereby effectively preventing wear of the conversion mechanism.

[0090] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0091] 10, 10A, 10B... Cylinder device 12... Body 14...Rod 16, 16B...Rod cover 20...First piston 22, 22A...Second piston 26...First cylinder chamber 28...Second cylinder chamber 34... Second fluid supply / discharge portion 36... Connection flow path 38...First port 40, 40B...Second port 42...expanded diameter portion 46...first rod 48...Second rod

Claims

1. a first cylinder chamber having a first piston; a second cylinder chamber having a second piston; a first rod connected to the first piston; a second rod that partially overlaps the first rod in the radial direction and protrudes from the body; a conversion mechanism that converts a displacement of a part of the axial direction of the first rod into a displacement of the second rod in a rotational direction, and transmits a displacement of another part of the axial direction of the first rod as a displacement of the second rod in the axial direction, The second piston is connected to the second rod.

2. 2. The cylinder device according to claim 1, wherein the conversion mechanism is located between the first piston and the second piston.

3. The cylinder device according to claim 1 , wherein the axial length of the second cylinder chamber is shorter than the axial length of the first cylinder chamber.

4. 2. The cylinder device according to claim 1, wherein the second cylinder chamber has an inner diameter larger than that of the second piston and has an expanded diameter portion that separates the second piston at an extrusion end position from an inner peripheral surface of the second cylinder chamber.

5. 5. The cylinder device according to claim 4, wherein the expanded diameter portion communicates with chambers on both sides in the axial direction of the second piston at the extrusion end position.

6. 2. The cylinder device according to claim 1, a first port that opens to an end of the second cylinder chamber in a first direction toward a retracted end position; a second port that opens to an end of the second cylinder chamber in a second direction toward the extrusion end position.

7. 7. The cylinder device according to claim 6, wherein the second port opens into the second cylinder chamber at a position shifted in the first direction from a packing of the second piston at the extrusion end position.

8. 7. The cylinder device according to claim 6, wherein the second cylinder chamber has a leak flow path on an inner circumferential surface thereof that allows the fluid supplied from the second port to escape toward the first direction beyond the second piston.

9. 9. The cylinder device according to claim 8, wherein the leak passage is a groove formed in the inner peripheral surface of the second cylinder chamber and extending in the axial direction.

10. 7. The cylinder device according to claim 6, a first fluid supply / discharge portion that opens toward the first direction side of the first cylinder chamber; a second fluid supply / discharge portion that opens to the second direction side of the first cylinder chamber, The body has a connecting passage that connects the second fluid supply / discharge portion and the second port.

11. 7. The cylinder device according to claim 6, wherein the second piston is rotatably connected to the second rod.

12. The cylinder device according to claim 10 or 11, a first packing provided on an outer circumferential portion of the second piston and positioned on the first direction side of the second port at a discharge end position of the second piston; a second packing provided on the outer periphery of the second piston and positioned on the second direction side of the second port at the extrusion end position of the second piston.

13. The cylinder device according to claim 10 or 11, a rod cover having a cover hole through which the second rod is inserted; a cover flow passage formed by a gap between the cover hole and the second rod, the cover flow passage fluidly connecting the second port and the second cylinder chamber; a sealing gasket that blocks the cover flow path at the stroke end of the second rod in the second direction and opens the cover flow path and the second cylinder chamber when the second rod moves in the first direction.

14. The cylinder device according to claim 10 or 11, a rod cover having a cover hole through which the second rod is inserted; a cover flow passage formed by a gap between the cover hole and the second rod, the cover flow passage fluidly connecting the second port and the second cylinder chamber; a rotary valve that is disposed in the cover flow path, rotates together with the second rod, and opens the cover flow path when the second rod is positioned at a predetermined angle.

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