Lock unit and level corrector

Abstract

A lock unit (22) comprises a first lock piston (36) and a lock ring (42) inside a first cylinder chamber (26). The lock ring (42) is disposed in a first tapered hole (36a) of the first lock piston (36) and has a diameter which reduces as the axial position changes to thereby fasten a rod (20) by wedge effect. The lock ring (42) has a plurality of lock pieces (44) each having an arc-shaped cross section. The lock pieces (44) occupy an angular range of less than 360° in the circumferential direction inside the first tapered hole (36a). The lock pieces (44) adjacent to each other form therebetween a gap (44c) that enables the lock pieces (44) to move in the circumferential direction.

Description

Lock Unit and Level Corrector

[0001] The present disclosure relates to a lock unit and a level corrector.

[0002] In a transfer system using a robot, a level corrector that causes the position of a suction pad to follow the shape of a workpiece is used to grip an inclined workpiece (Japanese Patent Laid-Open No. 2001-271858). The use of the level corrector offers advantages such as eliminating the need for tilting operation of the robot arm, reducing tact time, and eliminating the teaching man-hours required for tilting.

[0003] In a level corrector, since a large number of lock units each holding a rod are arranged side by side, further reduction in diameter and weight of the lock unit is desired.

[0004] However, when the lock unit is miniaturized, the diameter of the built-in lock piston is reduced, which restricts the thrust and causes a problem that the holding force for the rod becomes insufficient.

[0005] An object of the present disclosure is to solve the above problem.

[0006] According to a first aspect of the present disclosure, there is provided a lock unit comprising: a cylinder tube having a first cylinder chamber and allowing a rod to be inserted therethrough along an axis; a first lock piston disposed in the first cylinder chamber and having a first tapered hole through which the rod is inserted; and a lock ring disposed between the first tapered hole and the rod, the lock ring clamping the rod and restricting movement of the rod by relative axial displacement with respect to the first tapered hole, wherein the lock ring has an inner circumferential surface parallel to the outer circumferential surface of the rod and an outer circumferential surface parallel to the inner circumferential surface of the first tapered hole, the lock ring includes a plurality of lock pieces each having an arcuate cross-section perpendicular to the axial direction, an angular range occupied by the plurality of lock pieces in the circumferential direction inside the first tapered hole is smaller than 360°, and gaps allowing movement of the lock pieces in the circumferential direction and the radial direction are formed between the lock pieces.

[0007] A second aspect of the present disclosure is a level compensator comprising a rod and a plurality of locking units according to the first aspect through which the rod is inserted.

[0008] The locking unit of this disclosure can generate sufficient holding force on the rod while maintaining a small diameter.

[0009] The above-mentioned objectives, features, and advantages will be readily apparent from the following description of the embodiments, which will be illustrated with reference to the attached drawings.

[0010] Figure 1 is an explanatory diagram of the transfer system according to the first embodiment. Figure 2A is a perspective view of the lock unit according to the first embodiment, and Figure 2B is a side view of the lock unit in Figure 2A. Figure 3 is a cross-sectional view of the lock unit along the line III-III in Figure 2B (lock piston in the released position). Figure 4A is a perspective view of the lock ring, and Figure 4B is a cross-sectional view along the line IVB-IVB in Figure 4A. Figure 5 is a cross-sectional view of the lock unit along the line III-III in Figure 2B (lock piston in the locked position). Figure 6 is a cross-sectional view of the lock unit according to the second embodiment in the released position. Figure 7 is a cross-sectional view of the lock unit in Figure 6 in the locked position. Figure 8 is a perspective view of the lock unit according to the third embodiment.

[0011] (First Embodiment) The transfer system 10 according to this embodiment shown in Figure 1 comprises a plurality of suction pads 12, a level compensator 14 that supports the suction pads 12, a hand 16 that holds the level compensator 14, and a robot arm 18 that drives the hand 16. The suction pads 12 adhere to the surface of the workpiece W by negative pressure supplied through negative pressure piping (not shown). The level compensator 14 comprises a plurality of sets of rods 20 connected to the suction pads 12 and locking units 22 that can lock the rods 20. The level compensator 14 is mounted on the hand 16.

[0012] The transfer system 10 operates as follows. First, by driving the robot arm 18, a hand 16 equipped with multiple level compensators 14 and suction pads 12 is positioned on a workpiece W that has an incline or uneven surface. Then, the locks on the rods 20 by each lock unit 22 are released. With the locks released, the rods 20 become displaceable. With the locks released, the robot arm 18 is driven, pressing the multiple rods 20 against the workpiece W, causing the suction pads 12 to contact the surface of the workpiece W and stop. As a result, the multiple suction pads 12 are positioned to conform to the surface of the workpiece W. Next, the level compensators 14 lock the rods 20 in the stopping position using the lock unit 22. Then, the workpiece W is picked up through the suction pads 12, and by driving the robot arm 18, the workpiece W is transferred to a predetermined location.

[0013] Such a transfer system 10 is suitable for use in automated equipment lines in factories, etc. The level corrector 14 of this embodiment includes a miniaturized locking unit 22.

[0014] As shown in Figures 2A to 3, the locking unit 22 has a roughly rectangular parallelepiped-shaped cylinder tube 24 that extends long in the axial direction. The cylinder tube 24 has a first cylinder chamber 26 that extends axially inside. A first collar 28 is attached to the first end 24a of the cylinder tube 24 in the first direction, and a second collar 30 is attached to the second end 24b of the cylinder tube 24 in the second direction. The first collar 28 seals the first end of the first cylinder chamber 26 in the first direction, and the second collar 30 seals the second end of the first cylinder chamber 26 in the second direction.

[0015] A lock port 32 is formed near the first end of the cylinder tube 24, communicating with the first region 26a on the first direction side of the first cylinder chamber 26. The lock port 32 is a port to which air is supplied when locking the rod 20. In addition, a release port 34 is formed near the second end of the cylinder tube 24, communicating with the second region 26b on the second direction side of the first cylinder chamber 26. The release port 34 is a port to which air is supplied when unlocking the rod 20.

[0016] The first collar 28 has a first through-hole 28a that penetrates axially through its center. The first through-hole 28a is configured to allow the rod 20 to be inserted through it. A packing 28b is attached to the inner circumference of the first through-hole 28a to prevent air leakage through the gap between the rod 20 and the first through-hole 28a. The first collar 28 has a first annular projection 28c that extends a short distance in a second direction outward from the first through-hole 28a. The first annular projection 28c restricts the stroke range of the first lock piston 36 in the first direction. A receiving recess 28d is formed radially inward of the first annular projection 28c. A lock ring retainer 38 fits into the receiving recess 28d.

[0017] The lock ring retainer 38 comprises a base portion 38a, an extension portion 38b, and a through hole 38c. The base portion 38a fits into the receiving recess 28d. The outer diameter of the extension portion 38b is smaller than the outer diameter of the base portion 38a and has an outer diameter that allows it to be inserted into the first tapered hole 36a of the first lock piston 36. The extension portion 38b extends longer than the stroke range of the first lock piston 36 in the second direction. The extension portion 38b has a smooth outer surface 38d. The through hole 38c extends along the axis and passes through the lock ring retainer 38. The through hole 38c communicates with the first insertion hole 28a and allows the rod 20 to be inserted through it. The extension portion 38b of the lock ring retainer 38 prevents the lock ring 42 from moving in the first direction. The lock ring retainer 38 may be formed integrally with the first collar 28.

[0018] The second collar 30 has a second through-hole 30a that penetrates axially through its center. The second through-hole 30a is configured to allow the rod 20 to be inserted through it. A packing 30b is attached to the inner circumference of the second through-hole 30a. The packing 30b prevents air leakage through the gap between the rod 20 and the second through-hole 30a. The second collar 30 has a second annular projection 30c that extends a short distance in the first direction outward from the second through-hole 30a. The second annular projection 30c restricts the stroke range of the first lock piston 36 in the second direction. The lock cylinder portion 40 protrudes from the second annular projection 30c in the first direction.

[0019] The locking cylinder portion 40 is integrally formed with the second collar 30. The axial length of the locking cylinder portion 40 is shorter than the axial length of the locking ring retainer 38. The outer diameter of the locking cylinder portion 40 is such that it can be inserted into the first tapered hole 36a of the first locking piston 36. The locking cylinder portion 40 restricts the displacement of the locking ring 42 in the second direction. The locking cylinder portion 40 supports the locking ring 42 when the first locking piston 36 is displaced to the locked position.

[0020] A first lock piston 36 is housed inside the first cylinder chamber 26. The first lock piston 36 airtightly divides the first cylinder chamber 26 into a first region 26a and a second region 26b. The first lock piston 36 moves axially according to the pressure difference between the first region 26a and the second region 26b, and is displaced to a locked position or an unlocked position. The first lock piston 36 has a first tapered hole 36a, an inner circumferential packing 36b, an outer circumferential packing 36c, and a wear ring 36d.

[0021] The first tapered hole 36a is formed in a conical shape, with the smallest inner diameter near the end in the first direction and gradually increasing in diameter towards the second direction. The inner diameter of the first tapered hole 36a at the end in the first direction is slightly larger than the outer diameter of the extension portion 38b of the lock ring retainer 38. The extension portion 38b is inserted into a part of the first direction side of the first tapered hole 36a. Near the end in the second direction of the first tapered hole 36a, the lock cylinder portion 40 has an inner diameter into which it can be inserted. In the locked position of the first lock piston 36, the lock cylinder portion 40 is inserted into the first tapered hole 36a.

[0022] A smaller inclination angle of the inner circumferential surface 36e of the first lock piston 36, which forms the first tapered hole 36a, with respect to the central axis is preferable for generating a greater locking force. A suitable inclination angle is, for example, around 3°. A small inclination angle allows for both a smaller diameter for the first lock piston 36 and the generation of a large locking force.

[0023] The inner circumferential packing 36b is attached to the inner circumference of the first tapered hole 36a from the end in the first direction. The inner circumferential packing 36b contacts the outer surface 38d of the lock ring retainer 38, thereby preventing air leakage through the gap between the lock ring retainer 38 and the first tapered hole 36a. The inner circumferential packing 36b is positioned so as to be able to contact the lock ring retainer 38 throughout the entire stroke range of the first lock piston 36.

[0024] The outer circumferential packing 36c is positioned on the outer circumference of the first lock piston 36 and contacts the inner circumferential surface 24c of the cylinder tube 24. The wear ring 36d contacts the inner circumferential surface 24c of the cylinder tube 24, thereby suppressing the wobble of the first lock piston 36 and enabling smooth movement.

[0025] A lock ring 42 is positioned inside the first tapered hole 36a. The lock ring 42 is a cylindrical member as a whole, and has an inner diameter portion 42a extending parallel to the rod 20 and an outer diameter portion 42b formed parallel to the inner circumferential surface 36e of the first lock piston 36 that forms the first tapered hole 36a. The axial displacement of the lock ring 42 is restricted by the lock ring retainer 38 and the lock cylinder portion 40. By changing its relative axial position with respect to the first lock piston 36, the lock ring 42 exerts a wedge effect and generates a locking force that restricts the movement of the rod 20.

[0026] The lock ring 42 is composed of a plurality of locking pieces 44 that are completely separated in the circumferential direction. As shown in Figures 4A and 4B, the lock ring 42 is composed of three locking pieces 44. However, the number of locking pieces 44 is not limited to three, and may be two or four or more.

[0027] Each locking piece 44 has an arc-shaped cross-section perpendicular to the axial direction. The inner circumferential surface 44a of the locking piece 44 is a curved surface having a radius of curvature approximately the same as the outer diameter of the rod 20 and extends parallel to the axial direction. The outer circumferential surface 44b of the locking piece 44 is a conical surface parallel to the first tapered hole 36a.

[0028] Within the first tapered hole 36a, the angular range occupied by the three locking pieces 44 in the circumferential direction is less than 360°. Therefore, a gap 44c is formed between adjacent locking pieces 44. The locking pieces 44 are displaceable in the circumferential direction within the first tapered hole 36a due to the gap 44c. The circumferential length of the gap 44c is not necessarily uniform in the circumferential direction and may be unevenly distributed at one point in the circumferential direction. The axial length of the locking pieces 44 is shorter than the axial length of the first tapered hole 36a.

[0029] The gap 44c also allows for radial displacement of the locking piece 44. Therefore, when the rod 20 is removed from the locking unit 22, some of the locking piece 44 may be displaced inward so as to approach the central axis. In order to enable smooth mounting of the rod 20 even in such a case, as shown in Figure 3, enlarged diameter portions 44d are formed at the first and second ends of the inner circumferential surface 44a of the locking piece 44. The enlarged diameter portions 44d are formed such that the radius of curvature (inner diameter) gradually widens from the axial center of the locking piece 44 towards the ends. The ends of the enlarged diameter portions 44d have dimensions (radius of curvature) that are located outside the outer diameter of the rod 20 so that the tip of the rod 20 can be smoothly guided into the locking ring 42 even when the locking piece 44 is displaced to its maximum extent inward.

[0030] The lock ring 42 is formed to be slightly shorter than the axial distance between the lock ring retainer 38 and the lock cylinder portion 40, and is slightly displaceable in the axial direction. This prevents malfunctions caused by sticking between the lock ring 42 and the first lock piston 36.

[0031] The lock unit 22 of this embodiment is configured as described above. The operation of the lock unit 22 will now be explained.

[0032] With the rod 20 inserted through the lock unit 22, supplying air to the release port 34 and discharging the air from the lock port 32 causes the first lock piston 36 to be displaced to the release position shown in Figure 3. In the release position, the lock piece 44 of the lock ring 42 is located in the larger diameter portion of the first tapered hole 36a, so no force acts to bias the lock piece 44 inward. Therefore, the rod 20 does not receive a large frictional force from the lock piece 44 and can slide smoothly in the axial direction.

[0033] Furthermore, when air is supplied to the lock port 32 and released from the release port 34, the first lock piston 36 is displaced to the locked position, as shown in Figure 5. The lock ring 42 is displaced relative to the first tapered hole 36a in a direction that reduces its diameter. As a result, the lock ring 42 is biased inward by the inner circumferential surface 36e of the first lock piston 36 that forms the first tapered hole 36a, tightening the rod. Since the outer circumferential surface 44b of the lock piece 44 is formed parallel to the inner circumferential surface 36e of the first lock piston 36, the entire axial area of ​​the lock piece 44 is in surface contact with the inner circumferential surface 36e of the first lock piston 36.

[0034] Since each locking piece 44 is completely separated in the circumferential direction, each displaces in the radial direction without tilting with respect to the axial direction. The inner circumference of each locking piece 44 is pressed against the outer surface 20a of the rod 20 with a substantially uniform load distribution in the axial direction. At this time, the portion where the locking piece 44 is pressed inward by the first locking piston 36 and the portion where the locking piece 44 contacts the rod 20 coincide in the axial direction. With this configuration, the frictional force (locking force) between the locking piece 44 and the rod 20 is maximized, and a large locking force can be generated even with a limited thrust of the first locking piston 36.

[0035] The locking piece 44 described above is preferably made of a material with appropriate elasticity. For example, the locking piece 44 is preferably made of a resin material. In this case, by making the radius of curvature of the locking piece 44 smaller than the diameter of the outer surface 20a of the rod 20, the frictional force with the rod 20 can be reduced by configuring it so that only a part of the circumferential direction contacts the rod 20 in the released position. In the locked position, the locking piece 44 elastically deforms so that the entire inner surface 44a makes surface contact with the rod 20, thereby generating a large locking force. Note that the locking piece 44 is not limited to a resin material and may be made of metal or the like.

[0036] As described above, the locking unit 22 of this embodiment can generate a large locking force on the rod 20 while being made smaller in diameter.

[0037] (Second Embodiment) The lock unit 22A of this embodiment will be described below with reference to Figures 6 and 7. The lock unit 22A of this embodiment includes the same configuration as the lock unit 22 described with reference to Figures 2A to 5. In the lock unit 22A, components common to the lock unit 22 are given the same reference numerals, and their detailed description is omitted.

[0038] As shown in Figure 6, the lock unit 22A of this embodiment has a substantially rectangular parallelepiped-shaped cylinder tube 24A that extends long in the axial direction. The cylinder tube 24A has a first cylinder chamber 26 and a second cylinder chamber 26A that extend in the axial direction inside. A first collar 28 is attached to the first end 24a of the cylinder tube 24A in the first direction, and a second collar 30A is attached to the second end 24b of the cylinder tube 24A in the second direction. The first collar 28 seals the first end of the first cylinder chamber 26, and the second collar 30A seals the second end of the second cylinder chamber 26A in the second direction.

[0039] A lock port 32 is formed near the first end of the cylinder tube 24A, and a lock port 32A is formed near the second end of the cylinder tube 24A. The lock port 32A at the second end communicates with the second-direction region of the second cylinder chamber 26A. Air is supplied to the lock ports 32 and 32A when locking the rod 20. In addition, a release port 34 is formed in the axial center of the cylinder tube 24A, communicating with the second-direction portion of the first cylinder chamber 26 and the first-direction portion of the second cylinder chamber 26A. Air is supplied to the release port 34 when releasing the lock on the rod 20.

[0040] The first collar 28 has a first insertion hole 28a that penetrates axially through its center. The configuration of the first collar 28 is the same as that of the first collar 28 described with reference to Figure 3, so a detailed description is omitted. Furthermore, the second collar 30A of this embodiment has the same configuration as the first collar 28, and the second collar 30A is arranged by reversing the first collar 28 in the axial direction.

[0041] The lock unit 22A of this embodiment has an intermediate cover 46 in the center of the cylinder tube 24A. The intermediate cover 46 is positioned between the first cylinder chamber 26 and the second cylinder chamber 26A. However, the intermediate cover 46 does not airtightly separate the first cylinder chamber 26 and the second cylinder chamber 26A, and is installed so that air can flow between them. In this embodiment, the intermediate cover 46 includes an axial hole 46a, an annular groove 46b, and a pair of lock cylinder portions 40. The axial hole 46a extends along the axis of the intermediate cover 46 and is configured to allow the rod 20 to pass through. The annular groove 46b is a groove formed circumferentially on the outer circumference of the intermediate cover 46 and engages with a positioning pin 48 inserted into the release port 34. The annular groove 46b and the positioning pin 48 fix the intermediate cover 46 in the axial direction.

[0042] The locking cylinder portion 40 extends from the intermediate cover 46 in a first direction and a second direction, respectively. The locking cylinder portion 40 supports the locking ring 42 when the first locking piston 36 or the second locking piston 36A is displaced to the locked position.

[0043] A first lock piston (36) is accommodated inside the first cylinder chamber (26), and a second lock piston (36A) is accommodated inside the second cylinder chamber (26A). The first lock piston (36) and the second lock piston (36A) are configured in the same manner as the first lock piston (36) described with reference to FIG. 3. The second lock piston (36A) is arranged by inverting the first lock piston (36) in the axial direction. Accordingly, the diameter of the second tapered hole (37) of the second lock piston (36A) decreases as it goes toward the second direction. That is, the diameter reducing direction of the second tapered hole (37) is opposite to that of the first tapered hole (36a). The second tapered hole (37) is formed to have the same dimensions and inclination angle as the first tapered hole (36a), except that the diameter reducing direction is opposite.

[0044] A lock ring (42) is arranged inside each of the first lock piston (36) and the second lock piston (36A). Since the lock ring (42) is the same as the lock ring (42) described with reference to FIGS. 4A to 5, detailed description thereof is omitted.

[0045] The lock unit (22A) of the present embodiment is configured as described above. The operation of the lock unit (22A) will be described below.

[0046] In a state where the rod (20) is inserted through the lock unit (22A), when air is supplied to the release port (34) and air is discharged from the two lock ports (32, 32A), the first lock piston (36) and the second lock piston (36A) are displaced to the release position shown in FIG. 6. In the release position, the lock ring (42) of the first lock piston (36) is located at a portion where the diameter of the first tapered hole (36a) is large. Further, the lock ring (42) of the second lock piston (36A) is located at a portion where the diameter of the second tapered hole (37) is large. Therefore, in the first lock piston (36) and the second lock piston (36A), no force biasing the lock ring (42) inward acts. Accordingly, the rod (20) does not receive a large frictional force from the lock ring (42), and can smoothly slide in the axial direction.

[0047] Further, when air is supplied to the two lock ports 32, 32A and air is discharged from the central release port 34, as shown in FIG. 7, the first lock piston 36 and the second lock piston 36A are displaced to the lock position. In the lock position, the lock ring 42 of the first lock piston 36 and the lock ring 42 of the second lock piston 36A are biased inward to lock the rod 20.

[0048] As described above, the lock unit 22A of the present embodiment can generate approximately twice the locking force without increasing the diameter compared to the lock unit 22 described with reference to FIGS. 2 to 5. Further, in the lock unit 22A, by sharing the release port 34 for the first cylinder chamber 26 and the second cylinder chamber 26A, the flow path configuration can be simplified, and the number of tubes connected to the lock unit 22A can be reduced.

[0049] (Third Embodiment) Hereinafter, the lock unit 22B of the present embodiment will be described with reference to FIG. 8. The lock unit 22B is configured by connecting two lock units 22 described with reference to FIGS. 2A to 5 in the axial direction. In the lock unit 22B, configurations common to the lock unit 22 are denoted by the same reference numerals, and detailed description thereof is omitted.

[0050] As illustrated, in the lock unit 22B, the two lock units 22 have a connection hole 24e formed at the first end 24a and the second end 24b respectively. A connection pin 50 is attached to the connection hole 24e. Adjacent cylinder tubes 24 are connected in the axial direction by the connection pin 50 attached to the connection hole 24e. Further, the cylinder tube 24 includes a lock port 32 and a release port 34.

[0051] The four corners of the cylinder tube 24 are formed with connecting holes 51 similar to the lock ports 32 and release ports 34. The connecting holes 51 do not penetrate the side walls of the cylinder tube 24 and do not communicate with the internal cylinder chamber. The connecting holes 51 are used to connect to other adjacent cylinder tubes 24. That is, a connecting plate 52 is attached to the connecting hole 51 through a fastening member such as a screw or bolt. Two lock units 22 are firmly connected through the connecting plate 52.

[0052] In this embodiment, the locking unit 22B can increase the locking force of the rod 20 without increasing its diameter by connecting multiple locking units 22 in the axial direction.

[0053] With regard to the above embodiments, the following additional information is disclosed.

[0054] (Note 1) The locking units (22, 22A, 22B) of this disclosure include a cylinder tube (24, 24A) having a first cylinder chamber (26) through which a rod (20) is inserted along its axis, a first locking piston (36) disposed in the first cylinder chamber and having a first tapered hole (36a) through which the rod is inserted, and a locking ring (42) disposed between the first tapered hole and the rod, which tightens the rod and restricts its movement due to relative axial displacement with respect to the first tapered hole. The lock ring comprises a plurality of lock pieces (44) having an inner surface (44a) parallel to the outer surface of the rod and an outer surface (44b) parallel to the inner surface (36e) of the first tapered hole, and having a cross section perpendicular to the axial direction that is formed in an arc shape, wherein the angular range occupied by the plurality of lock pieces in the circumferential direction within the first tapered hole is less than 360°, and a gap (44c) is formed between the lock pieces that allows movement of the lock pieces in the circumferential and radial directions.

[0055] This locking unit can generate a large locking force even when the thrust of the first locking piston is limited, thus allowing the diameter of the first locking piston to be reduced.

[0056] (Note 2) The locking unit described in Note 1, wherein the axial length of the locking piece is shorter than the axial length of the first tapered hole, and the entire axial area of ​​the locking piece may be in surface contact with the inner circumferential surface of the first tapered hole at the locked position of the locking piston in which the movement of the rod is restricted. This locking unit can efficiently convert the thrust of the locking piston into a locking force.

[0057] (Note 3) In the locking unit described in Note 2, at the locking position, the portion where the locking piece and the first tapered hole make surface contact and the portion where the locking piece and the rod make surface contact coincide in the axial direction, and the locking piece tightens the rod with a uniform load distribution in the axial direction. This locking unit can maximize the frictional force between the locking piece and the rod, and therefore can generate a greater locking force.

[0058] (Note 4) A locking unit according to any one of Notes 1 to 3 may have an enlarged diameter portion (44d) formed at the axial end of the inner circumferential surface of the locking piece, such that the radius of curvature gradually increases from the axial center of the locking piece toward the end. This locking unit allows for smooth insertion of the rod.

[0059] (Note 5) A locking unit as described in any one of Notes 1 to 4, comprising: a locking cylinder portion (40) that restricts the axial displacement of the locking ring in response to the displacement of the first locking piston to the locked position; and a locking ring retainer (38) that restricts the axial displacement of the locking ring in response to the displacement of the locking piston to the released position, wherein the locking ring retainer may extend into the interior of the first tapered hole over a range that is longer in the axial direction than the stroke range of the locking piston. In this locking unit, when the first locking piston is displaced to the locked position, the area in which the first tapered hole can contact the entire outer circumference of the locking ring becomes larger. Therefore, the locking unit can efficiently generate locking force without increasing the overall length of the first locking piston.

[0060] (Note 6) In the locking unit described in Note 5, the first locking piston may be provided with an inner circumferential packing (36b) that contacts the outer surface (38d) of the locking ring retainer and seals the gap between the rod and the first tapered hole. By providing an inner circumferential packing on the locking ring retainer, the overall length of the locking cylinder portion of this locking unit can be shortened, the entire area of ​​the locking ring can contact the first locking piston in the locked position, and thrust can be efficiently converted into locking force.

[0061] (Note 7) A locking unit according to any one of Notes 1 to 6, wherein the locking ring may be made of a resin material. In this locking unit, by making the locking ring out of an elastic resin material, the locking ring can exert a greater locking force.

[0062] (Note 8) A locking unit according to any one of Notes 1 to 7, further comprising: a second cylinder chamber (26A) aligned axially with the first cylinder chamber; and a second locking piston (36A) disposed in the second cylinder chamber and having a second tapered hole (37) through which the rod is inserted, wherein the locking ring is provided between the second locking piston and the rod. This locking unit can double the locking force without increasing the diameter.

[0063] (Note 9) The locking unit described in Note 8 may have the diameter reduction direction of the first tapered hole and the diameter reduction direction of the second tapered hole in opposite directions. This locking unit simplifies the connection piping by sharing some ports.

[0064] (Note 10) The level compensator (14) of the present disclosure comprises a rod and a plurality of lock units described in any one of Notes 1 to 9 through which the rod is inserted. This level compensator can accommodate a large number of lock units in a small area because it is equipped with smaller diameter lock units.

[0065] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

Claims

1. A cylinder tube (24, 24A) having a first cylinder chamber (26) through which a rod (20) is inserted along its axis; a first lock piston (36) disposed in the first cylinder chamber and having a first tapered hole (36a) through which the rod is inserted; a lock ring (42) disposed between the first tapered hole and the rod, which restricts the movement of the rod by tightening the rod due to the relative axial displacement with respect to the first tapered hole, wherein the lock ring has an inner surface (44a) parallel to the outer surface of the rod and an outer surface (44b) parallel to the inner surface (36e) of the first tapered hole, and comprises a plurality of lock pieces (44) whose cross-section perpendicular to the axial direction is formed in an arc shape. A locking unit (22, 22A, 22B) is configured such that, within the first tapered hole, the angular range occupied by the plurality of locking pieces in the circumferential direction is less than 360°, and a gap (44c) is formed between the locking pieces that allows the locking pieces to move in the circumferential and radial directions.

2. A locking unit according to claim 1, wherein the axial length of the locking piece is shorter than the axial length of the first tapered hole, and the entire axial area of ​​the locking piece is in surface contact with the inner circumferential surface of the first tapered hole at the locked position of the first locking piston in which the movement of the rod is restricted.

3. A locking unit according to claim 2, wherein, in the locked position, the portion of the locking piece that makes surface contact with the first tapered hole and the portion of the locking piece that makes surface contact with the rod coincide in the axial direction, and the locking piece tightens the rod with a uniform load distribution in the axial direction.

4. A locking unit according to any one of claims 1 to 3, wherein an enlarged diameter portion (44d) is formed at the axial end of the inner circumferential surface of the locking piece, such that the radius of curvature gradually increases from the axial center of the locking piece toward the end.

5. A locking unit according to any one of claims 1 to 4, comprising: a locking cylinder portion (40) that restricts the axial displacement of the locking ring with respect to the displacement of the first locking piston to the locked position; and a locking ring retainer (38) that restricts the axial displacement of the locking ring with respect to the displacement of the first locking piston to the released position, wherein the locking ring retainer extends into the first tapered hole over a range that is longer in the axial direction than the stroke range of the first locking piston.

6. A locking unit according to claim 5, wherein the first locking piston is provided with an inner circumferential packing (36b) that contacts the outer surface (38d) of the locking ring retainer and seals the gap between the rod and the first tapered hole.

7. A locking unit according to any one of claims 1 to 6, wherein the locking ring is formed of a resin material.

8. A locking unit according to any one of claims 1 to 7, further comprising: a second cylinder chamber (26A) aligned axially with the first cylinder chamber; a second locking piston (36A) disposed in the second cylinder chamber and having a second tapered hole (37) through which the rod is inserted; and the locking ring being located between the second locking piston and the rod.

9. A locking unit according to claim 8, wherein the diameter reduction direction of the first tapered hole and the diameter reduction direction of the second tapered hole are in opposite directions.

10. A level compensator comprising a rod and a plurality of locking units according to any one of claims 1 to 9 through which the rod is inserted.

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