Torque limiter

Abstract

To make a torque limiter function, even when a portion projecting from an outer periphery of a cylindrical member exists.SOLUTION: A torque limiter 10 has a shaft member 11, a cylindrical member 12, a cover 13 positioned on an outer peripheral side of the cylindrical member 12 and fixed to the shaft member 11, and a shear valve 14. The cylindrical member 12 has a hydraulic pressure expansion chamber 34, a hydraulic passage 35, and a fitting hole 33 coupled with the hydraulic passage 35. The shear valve 14 has a main body 41, a head part 42 having a portion positioned in a range of a through hole 33 of the cover 13, and a fastening operation part 43 used when the shear valve 14 is mounted and removed. An accommodation space 20, which is mounted to the cylindrical member 12 and in which some of parts projecting from an outer periphery 322 of the cylindrical member 12 are positioned, is provided between an inner face of the cover 13 and the outer periphery 322.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a torque limiter. [Background technology]

[0002] Patent Document 1 discloses a torque limiter having a shear valve. When a low torque is applied, the torque limiter rotates the shaft member and the cylindrical member together to transmit torque. In contrast, when a high torque is applied, the shear valve is sheared, causing the shaft member and the cylindrical member to rotate relative to each other, blocking the torque transmission. By placing the torque limiter in the middle of the power transmission path, it becomes possible to protect the device or machine from overtorque. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-145389 A Summary of the Invention [Problem to be solved by the invention]

[0004] Fig. 7 is a longitudinal sectional view of a torque limiter having a conventional shear valve. Torque limiter 90 has a cylindrical member 91 and a shaft member 99. Cylindrical member 91 has a hydraulic expansion chamber 92 therein. Oil is supplied to hydraulic expansion chamber 92 through a coupler 93 (see Fig. 8). Fig. 8 is a transverse sectional view showing a portion of conventional torque limiter 90. The hydraulic pressure applied to the hydraulic expansion chamber 92 causes the inner periphery 911 of the cylindrical member 91 to elastically deform toward the shaft member 99. As a result, when a low torque is applied to the torque limiter 90, the frictional force (frictional engagement) generated between the cylindrical member 91 and the shaft member 99 causes the cylindrical member 91 and the shaft member 99 to rotate together, and the torque limiter 90 transmits torque.

[0005] The shear valve 94 (see FIG. 8) has a main body portion 941 attached to the mounting hole 912 of the cylindrical member 91, a fastening working portion 942, and a head portion 943. The fastening working portion 942 has a shape (e.g., a hexagonal shape) that allows it to be gripped by a tool when attaching and removing the shear valve 94 to and from the mounting hole 912. The head portion 943 is located within a radial range of a cover 98 fixed to a shaft member 99. In the conventional example shown in FIG. 8, a through hole 971 is provided in the cover 98, and a T-shaped grooved cover 95 is attached to the through hole 971. The head portion 943 is located in the T-shaped groove.

[0006] When high torque acts on the torque limiter 90, the cylindrical member 91 and the shaft member 99 rotate relative to each other against the frictional force. Then, the head 943 of the shear valve 94 is cut (sheared) by the T-shaped grooved cover 95, and the hydraulic pressure in the hydraulic expansion chamber 92 is released. Then, the frictional engagement is released, the cylindrical member 91 and the shaft member 99 rotate relative to each other, and the torque transmission is interrupted.

[0007] In the case of the conventional torque limiter 90, the fastening working portion 942 of the shear valve 94 and the coupler 93 for sealing oil in the hydraulic expansion chamber 92 are located radially inward from the outer circumferential surface 913 of the cylindrical member 91. This is to prevent some of the parts attached to the cylindrical member 91 (the tip of the coupler 93, the fastening working portion 942 of the shear valve 94) from interfering with the cover 98 fixed to the shaft member 99 when high torque acts on the torque limiter 90 and the cylindrical member 91 and the shaft member 99 rotate relative to each other. However, there are cases where it is preferable that a part of the part attached to the cylindrical member 91 protrudes from the outer circumferential surface 913 of the cylindrical member 91 .

[0008] For example, if coupler 93 becomes larger than before, hole 914 for attaching coupler 93 becomes deeper, but in this case, hole 914 and attachment hole 912 become closer to each other, and stress near attachment hole 912 increases, which may result in a weak point in terms of strength. For this reason, it may be preferable to make hole 914 shallower and have a part of coupler 93 attached to hole 914 protrude from outer circumferential surface 913 of tubular member 91. Furthermore, when the fastening working portion 942 of the shear valve 94 from which the head 943 has been cut off is grasped with a tool to remove the used shear valve 94, it may be preferable for the fastening working portion 942 to protrude from the outer circumferential surface 913 of the tubular member 91 in order to make this operation easier.

[0009] Therefore, an object of the present invention is to provide a new technical means for enabling a torque limiter to function even when there is a portion protruding from the outer circumferential surface of a cylindrical member. [Means for solving the problem]

[0010] (1) A torque limiter according to the present invention includes a shaft member, a cylindrical member located radially outward of the shaft member, a cover located on an outer circumferential side of the cylindrical member and fixed to the shaft member, and a shear valve attached to the cylindrical member, the tubular member has a hydraulic expansion chamber provided inside the tubular member, a hydraulic passage extending from the hydraulic expansion chamber to the outer circumferential side of the tubular member, and a mounting hole connected to the hydraulic passage and opening on the outer circumferential surface of the tubular member, The shear valve has a main body attached to the mounting hole, a head having a portion located within the range of a through hole of the cover, and a fastening part located between the main body and the head and used when attaching and detaching the shear valve, A storage space is provided between the inner surface of the cover and the outer peripheral surface of the tubular member in which a portion of a part attached to the tubular member and protruding from the outer peripheral surface of the tubular member is located.

[0011] In the torque limiter having the above-mentioned configuration, the inner peripheral portion of the cylindrical member is elastically deformed toward the shaft member by the hydraulic pressure applied to the hydraulic expansion chamber. As a result, when a low torque is applied to the torque limiter, the cylindrical member and the shaft member rotate together due to the frictional force (frictional engagement) generated between them, and the torque limiter transmits torque. When a high torque acts on the torque limiter, the cylindrical member and the shaft member rotate relative to each other against the frictional force. Then, the head of the shear valve is cut (sheared) by a part of the cover fixed to the shaft member, and the hydraulic pressure in the hydraulic expansion chamber is released. Then, the frictional engagement is released, the cylindrical member and the shaft member rotate relative to each other, and the torque transmission is interrupted.

[0012] When the cylindrical member and the shaft member rotate relative to each other, the storage space makes it possible to prevent interference between a part of the part protruding from the outer circumferential surface of the cylindrical member and the cover fixed to the shaft member. Even if there is a part protruding from the outer circumferential surface of the cylindrical member, the torque limiter can function.

[0013] (2) Preferably, the storage space has a shape that conforms to the cylindrical outer circumferential surface of the tubular member. For example, when the cover has a cylindrical shape, an annular space formed between the inner surface (inner circumferential surface) of the cover and the outer circumferential surface of the tubular member serves as the storage space.

[0014] (3) Preferably, the fastening portion is located in the storage space radially outward from an outer circumferential surface of the tubular member and radially inward from an inner surface of the cover. In the above configuration, the fastening portion of the shear valve is located so as to protrude radially outward from the outer circumferential surface of the tubular member. This makes it easier to bring a tool close to the fastening portion when removing the shear valve from the mounting hole after the head has been cut off. As a result, the removal of the used shear valve becomes easier.

[0015] (4) Since the storage space is provided between the inner surface of the cover and the outer peripheral surface of the tubular member, the head of the cut shear valve may enter the storage space and become pinched between the cover and the tubular member, which may adversely affect the operation of the torque limiter. Therefore, preferably, the torque limiter of any one of (1) to (3) further has a covering member attached to the outer periphery of the cover and covering the through hole, and a spacer attached to the through hole, and the head has an extension portion extending radially outward from the fastening working portion of the tubular member, and a flange portion protruding circumferentially from the extension portion of the tubular member, and the spacer has an annular claw portion located between the flange portion and the fastening working portion and protruding toward the extension portion, and the inner peripheral contour shape of the claw portion is smaller than the outer peripheral contour shape of the flange portion. In the case of the above-mentioned configuration, the cut head portion is held between the covering member and the claw portion of the spacer, and is prevented from entering the storage space.

[0016] (5) Preferably, any one of the torque limiters of (1) to (4) further has a coupler attached to the outer periphery of the tubular member for supplying oil to the hydraulic expansion chamber, and a portion of the coupler is located in the storage space radially outward from the outer periphery of the tubular member and radially inward from the inner surface of the cover. In the above configuration, a portion of the coupler protrudes from the outer circumferential surface of the tubular member but is located within the radial range of the storage space, and when the tubular member and the shaft member rotate relative to each other, the portion of the coupler protruding from the outer circumferential surface of the tubular member is prevented from interfering with the cover fixed to the shaft member.

[0017] (6) Preferably, in the torque limiter of (4), the spacer has a pair of wall portions that fit into the through hole, and between the pair of wall portions is an opening that exposes the inner surface of the through hole, and the opening is located on both circumferential sides of the torque limiter. In the case of the above-mentioned configuration, the spacer is attached to the through hole of the cover in the order of the first wall portion, the first opening portion, the second wall portion, and the second opening portion. The first opening portion and the second opening portion expose the inner circumferential surface of the through hole, in both circumferential regions of the torque limiter. When a high torque acts on the torque limiter, the cylindrical member and the shaft member rotate relative to each other, and the head of the shear valve is cut off by the cover. The head can directly contact the inner circumferential surface of the through hole of the cover, not the wall of the spacer. Therefore, although the spacer is attached to the through hole, the head is easily cut off by the through hole.

[0018] (7) When the coupler is long, the hole for attaching the coupler may become deep. Therefore, in the torque limiter of (5) above, preferably, the cylindrical member has a second attachment hole that opens on the outer circumferential surface of the cylindrical member in order to attach the coupler, and the central axis of the second attachment hole is inclined with respect to the radial direction of the cylindrical member. In the case of the above configuration, the second mounting hole does not need to be formed deep in the radial direction of the tubular member, compared to a case in which the central axis of the second mounting hole coincides with the radial direction of the tubular member.

[0019] (8) Preferably, in any one of the torque limiters (1) to (7), the cover has a cover body fixed to the shaft member and a ring-shaped shear plug removably attached to a secondary through hole provided in the cover body, and a central hole of the shear plug becomes the through hole in which the head is located. In the above configuration, the head of the shear valve comes into contact with the central hole (through hole) of the shear plug and is cut off. Even if the shear plug is damaged through repeated use, it is possible to replace the shear plug without replacing the cover body. In addition, by removing the shear plug, the opening in the cover becomes wider. If the torque limiter is to be readjusted, by removing the shear plug, access to the shear valve becomes easier. Effect of the Invention

[0020] According to the torque limiter of the present invention, even if there is a portion protruding from the outer circumferential surface of the cylindrical member, the torque limiter can function. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a vertical sectional view showing an embodiment of a torque limiter according to the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of the torque limiter shown in FIG. 1 taken along an arrow II. [Diagram 3] FIG. 3 is an enlarged cross-sectional view showing the shear valve and its surroundings. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing the head portion of the shear valve and its surroundings. [Diagram 5] FIG. 5 is an enlarged cross-sectional view showing the head portion of the shear valve and its surroundings. [Figure 6] FIG. 6 is a perspective view of a spacer. [Figure 7] FIG. 7 is a vertical sectional view of a torque limiter having a conventional shear valve. [Figure 8] FIG. 8 is a cross-sectional view showing a portion of a conventional torque limiter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] [Overall configuration of torque limiter] Fig. 1 is a vertical cross-sectional view showing one embodiment of a torque limiter of the present invention. The torque limiter 10 shown in Fig. 1 has a shaft member 11, a cylindrical member 12, a cover 13, a shear valve 14, a covering member 15, a first ball bearing 18, and a second ball bearing 19. The shaft member 11 has a cylindrical main body 21 that is long in one direction. An outer circumferential surface 211 of the main body 21 has a cylindrical shape with the central axis C of the shaft member 11 as its center.

[0023] The directions of the torque limiter 10 of the present disclosure are defined below. The direction along the central axis C of the shaft member 11 and the direction parallel to the central axis C are the "axial direction" of the torque limiter 10. The direction perpendicular to the central axis C is the "radial direction" of the torque limiter 10. The direction along a circle centered on the central axis C is the "circumferential direction" of the torque limiter 10.

[0024] The cylindrical member 12 has a first cylindrical portion 31 and a second cylindrical portion 32. The first cylindrical portion 31 has a cylindrical shape and has a cylindrical inner peripheral surface 311 that can come into contact with the outer peripheral surface 211 of the shaft member 11. Lubricant for preventing seizure is present between the outer peripheral surface 211 of the shaft member 11 and the inner peripheral surface 311 of the first cylindrical portion 31. The second cylindrical portion 32 has a cylindrical inner peripheral surface 321 that can come into contact with the cylindrical outer peripheral surface 312 of the first cylindrical portion 31. The cylindrical member 12 having the first cylindrical portion 31 and the second cylindrical portion 32 is located radially outward of the shaft member 11.

[0025] Fig. 2 is an enlarged cross-sectional view of the torque limiter shown in Fig. 1 taken along the arrow II. In Figs. 1 and 2, the second cylindrical portion 32 has a mounting hole 33 for the shear valve 14, an annular hydraulic expansion chamber 34, and a hydraulic passage 35. The hydraulic expansion chamber 34 is provided with a predetermined length along the axial direction. The hydraulic passage 35 is provided extending from the hydraulic expansion chamber 34 to the outer periphery of the second cylindrical portion 32. The mounting hole 33 is connected to the hydraulic passage 35 and opens at the outer periphery 322 of the second cylindrical portion 32.

[0026] The first ball bearing 18 and the second ball bearing 19 are attached between the shaft member 11 and the cylindrical member 12. As will be described later, when the shaft member 11 and the cylindrical member 12 rotate relative to each other, the first ball bearing 18 and the second ball bearing 19 support the shaft member 11 and the cylindrical member 12 so that they can rotate freely relative to each other.

[0027] The cover 13 is located on the outer circumferential side of a portion of the tubular member 12 (second tubular portion 32) and fixed to the shaft member 11. The cover 13 is also called a cover tube. The shaft member 11 has a connecting portion 22 extending radially from a portion of the first side (the right side in the case of FIG. 1 ) in the axial direction of the main body portion 21. The cover 13 is attached to the connecting portion 22, for example, by a bolt or the like. The cover 13 in this embodiment has a shape that is continuous in the circumferential direction (annular, cylindrical), but may have a shape that is discontinuous in the circumferential direction.

[0028] The cover 13 is provided with a through hole 51 in which the head 42 of a shear valve 14 (see FIG. 2), which will be described later, is positioned. In this embodiment, the cover 13 has a cover body 52 fixed to the shaft member 11 (connecting portion 22), and a ring-shaped shear plug 54 provided on the cover body 52. ​​The cover body 52 is provided with a secondary through hole 53. The secondary through hole 53 has a female threaded hole. The shear plug 54 has a male threaded portion on its outer periphery. The female threaded hole and male threaded portion allow the shear plug 54 to be detachably attached to the secondary through hole 53.

[0029] The through hole 51 and the sub through hole 53 are holes that radially penetrate the cover 13. The central hole of the shear plug 54 is the through hole 51, in which the head 42 of the shear valve 14 is positioned. Since the cover 13 is annular (cylindrical), the inner circumferential surface 132 of the cover 13 has a cylindrical shape. The radially inner side surface 541 of the shear plug 54 is included in the inner circumferential surface 132 of the cover 13.

[0030] In this embodiment, a spacer 16 is attached to the through hole 51. The spacer 16 is made of rubber. The shear plug 54 is made of steel. The shaft member 11, the cylindrical member 12, and the cover 13 are also made of steel. The structure and function of the spacer 16 will be described later. The covering member 15 is attached to the outer circumferential side of the cover 13 to cover the through hole 51. In the case of this embodiment, the covering member 15 is a belt-shaped member (band member) and is attached along the outer circumferential surface 131 of the cover 13. The covering member 15 is made of metal.

[0031] The shear valves 14 are attached to the second tubular portion 32 of the tubular member 12. The shear valves 14 are attached by screwing into the mounting holes 33. The number of shear valves 14 (four in the present disclosure) is the same as the number of mounting holes 33. In the present embodiment, the mounting holes 33 are positioned on the outer circumferential surface 322 of the second tubular portion 32 at equal intervals in the circumferential direction.

[0032] 3 is an enlarged cross-sectional view showing the shear valve 14 and its surroundings. The shear valve 14 has a main body 41 that is screwed into the mounting hole 33, a head 42, and a fastening working portion 43. The fastening working portion 43 is located between the main body 41 and the head 42. At least a portion of the head 42 (a flange portion 422 described below) is located within the range of a through hole 51 of the cover 13. The range of the through hole 51 refers to the range of the through hole 51 in the radial direction of the torque limiter 10. More specifically, at least a portion of the head 42 (a flange portion 422 described below) is located between the outer peripheral surface 131 and the inner peripheral surface 132 of the cover 13.

[0033] When the shear valve 14 (main body portion 41) is fitted and attached in the attachment hole 33, the fastening working portion 43 and the head 42 are located radially outward from the outer circumferential surface 322 of the second tubular portion 32. The fastening working portion 43 is not located within the range of the through hole 51. In other words, the entire fastening working portion 43 is located radially outward from the outer circumferential surface 322 of the second tubular portion 32 and radially inward from the inner circumferential surface 132 of the cover 13.

[0034] The head 42 has a T-shape. That is, the head 42 has an extension 421 extending radially outward from the fastening working portion 43, and a flange 422 protruding in the circumferential direction from the extension 421. When viewed from the radially outside, the flange 422 is circular. When viewed from the radially outside, the fastening working portion 43 is polygonal, for example, hexagonal. The extension 421 has a circular cross section. The diameter of the extension 421 is smaller than the diameter of the flange 422, and the diameter of the extension 421 is smaller than the diameter of the circumscribing circle of the fastening working portion 43. As will be described later, the head 42 is cut (sheared) at the extension 421.

[0035] The outer peripheral contour shape of the fastening working part 43 is, for example, a hexagon as described above. The fastening working part 43 is used when installing and removing the shear valve 14. The fastening working part 43 is also called a nut part, and is gripped by a tool, and the shear valve 14 is rotated by the tool.

[0036] The shear valve 14 has a tube (passage) 45 therein. The tube 45 extends in the radial direction of the torque limiter 10 when the shear valve 14 is fixed in the mounting hole 33. When the shear valve 14 is mounted in the mounting hole 33, a radially inner end 451 of the tube 45 is connected to the hydraulic passage 35. The tube 45 communicates with the hydraulic expansion chamber 34 via the hydraulic passage 35. A radially outer end 452 of the tube 45 extends to the head 42 and terminates inside the head 42. In other words, the tube 45 is sealed at its radially outer end 452.

[0037] As shown in Fig. 2, the torque limiter 10 has a coupler 17 for supplying oil to the hydraulic expansion chamber 34. The coupler 17 is attached to the outer circumferential portion 323 of the tubular member 12 (second tubular portion 32). The tubular member 12 (second tubular portion 32) has a second mounting hole 36 that opens at the outer circumferential surface 322 in order to attach the coupler 17. The coupler 17 has a male threaded portion. The second mounting hole 36 has a female threaded hole. The coupler 17 is attached by screwing into the second mounting hole 36 by means of the male threaded portion and the female threaded portion.

[0038] A fill passage 37 is provided between the second mounting hole 36 and the first mounting hole 33 for the shear valve 14. The coupler 17 can be connected to a lubrication device (not shown). The lubrication device supplies pressurized oil to the hydraulic expansion chamber 34 through the coupler 17, the fill passage 37, a portion of the mounting hole 33, and the hydraulic passage 35.

[0039] The central axis C1 of the second mounting hole 36 for the coupler 17 is inclined with respect to the radial direction of the tubular member 12. In Figures 2 and 3, the inclination angle of the central axis C1 with respect to the reference line in the radial direction of the tubular member 12 is indicated by θ. The central axis of the first mounting hole 33 for the shear valve 14 coincides with the reference line in the radial direction of the tubular member 12.

[0040] In FIG. 2, the second cylindrical portion 32 of the cylindrical member 12 has a positioning hole . The cover body 52 of the cover 13 has a coupler hole 55 and a pin hole 56. The coupler hole 55 and the pin hole 56 are holes that penetrate the cover body 52 in the radial direction.

[0041] When assembling the torque limiter 10, the circumferential position of the positioning hole 38 is aligned with the circumferential position of the pin hole 56. In this state, a pin (not shown) is inserted into the positioning hole 38 and the pin hole 56. Then, the circumferential position of the first mounting hole 33 in the cylindrical member 12 is aligned with the circumferential position of the through hole 51 in the cover 13. Furthermore, the circumferential position of the coupler hole 55 is aligned with the circumferential position of the second mounting hole 36. The pin prevents relative circumferential movement between the cover 13 and the cylindrical member 12. This allows the shear valve 14 to be attached to the first mounting hole 33, and the coupler 17 to be attached to the second mounting hole 36. When the assembly of the torque limiter 10 is complete, the pin is removed.

[0042] A storage space 20 is provided between the inner surface (inner circumferential surface 132) of the cover 13 and the outer circumferential surface 322 of the tubular member 12. In the storage space 20, a part of a part attached to the tubular member 12 (second tubular portion 32) and protruding from the outer circumferential surface 322 of the tubular member 12 (second tubular portion 32) is located. In this embodiment, the part is the coupler 17, and is also the shear valve 14 with the head 42 cut off.

[0043] The fastening working portion 43 of the shear valve 14 protrudes from the outer circumferential surface 322 of the second tubular portion 32. The fastening working portion 43 is located in the storage space 20 which is radially outward from the outer circumferential surface 322 of the tubular member 12 (second tubular portion 32) and radially inward from the inner surface (inner circumferential surface 132) of the cover 13. A portion 171 of the coupler 17 protrudes from the outer circumferential surface 322 of the second cylindrical portion 32. The portion 171 of the coupler 17 is located in the storage space 20 which is radially outward from the outer circumferential surface 322 of the cylindrical member 12 (second cylindrical portion 32) and radially inward from the inner surface (inner circumferential surface 132) of the cover 13. As a modified example, although not shown, the coupler 17 may not protrude from the outer circumferential surface 322 of the second tubular portion 32, and the entire coupler 17 may be located radially inward from the outer circumferential surface 322. The parts protruding from the outer circumferential surface 322 of the tubular member 12 are not limited to the coupler 17 and the shear valve 14. The parts protruding from the outer circumferential surface 322 may be other parts as long as a part of the parts is located in the storage space 20.

[0044] The storage space 20 has a shape that follows the cylindrical outer peripheral surface 322 of the tubular member 12. In the present embodiment, the inner surface (132) of the cover 13 is cylindrical, and the outer peripheral surface 322 of the second tubular portion 32 is cylindrical. Therefore, the storage space 20 has a ring shape that follows the outer peripheral surface 322.

[0045] The radial dimension E of the storage space 20 only needs to be larger than the dimension (height dimension) of the fastening working portion 43. Note that the dimension (height dimension) of the fastening working portion 43 is the dimension in the radial direction of the torque limiter 10. In the case of this embodiment, the dimension E is smaller than twice the dimension (height dimension) of the fastening working portion 43. The radial dimension E of the storage space 20 can be, for example, 0.5% or more and 10% or less of the radius R on the outer peripheral surface 322 of the cylindrical member 12 (second cylindrical portion 32).

[0046] The spacer 16 will be described. FIG. 4 is an enlarged cross-sectional view showing the head portion 42 of the check valve 14 and its surroundings. FIG. 4 is a cross-sectional view seen from the direction along the central axis C (see FIG. 1) of the torque limiter 10, similar to FIGS. 2 and 3. FIG. 5 is an enlarged cross-sectional view showing the head portion 42 of the check valve 14 and its surroundings. FIG. 5 is a view seen along the circumferential direction of the torque limiter 10. That is, FIG. 5 is a view seen from a direction orthogonal to the direction shown in FIG. 4. FIG. 6 is a perspective view of the spacer 16.

[0047] The spacer 16 has an annular spacer main body 64 and an annular claw portion 61. The claw portion 61 protrudes radially inward of the spacer main body 64 from the spacer main body 64. The annular claw portion 61 is located between the flange portion 422 of the check valve 14 and the fastening working portion 43 and protrudes toward the extension portion 421 side. As shown in FIG. 5, the inner peripheral contour shape of the claw portion 61 is smaller than the outer peripheral contour shape of the flange portion 422. In the case of this embodiment, since the claw portion 61 is annular and the flange portion 422 is circular, the inner diameter D2 of the claw portion 61 is smaller than the outer diameter D1 of the flange portion 422 (D2 < D1). Therefore, as will be described later, the cut portion of the head portion 42 including the flange portion 422 is held between the covering member 15 and the claw portion 61, and is prevented from entering the storage space 20.

[0048] The spacer 16 has a pair of wall portions 62 that fit into the through hole 51. The wall portions 62 are provided extending from a spacer body 64 in the radial direction of the torque limiter 10. Each of the pair of wall portions 62 covers a part of the inner circumferential surface 511 of the through hole 51. In contrast, an opening 63 that exposes the inner circumferential surface 511 of the through hole 51 is provided between the pair of wall portions 62. The opening 63 is located on both sides in the circumferential direction of the torque limiter 10. With this configuration, the spacer 16 is mounted in the through hole 51 in the order of the first wall portion 62, the first opening 63, the second wall portion 62, and the second opening 63. As shown in FIG. 5, the first opening 63 and the second opening 63 expose the regions on both sides in the circumferential direction of the torque limiter 10 of the inner circumferential surface 511 of the through hole 51.

[0049] As will be explained later, when a high torque acts on the torque limiter 10, the cylindrical member 12 and the shaft member 11 rotate relative to each other, and the head 42 of the shear valve 14 is cut off by the shear plug 54 of the cover 13. At this time, the head 42 can directly contact the inner circumferential surface 511 of the through hole 51, not the wall portion 62 of the spacer 16. Although the rubber spacer 16 is attached to the through hole 51, the spacer 16 does not get in the way (does not act as a buffer material) when the head 42 is cut off. The head 42 is easily cut off by the shear plug 54 having the through hole 51. During this cutting, the claw portion 61 of the spacer 16 is elastically deformed.

[0050] The spacer body 64 has a first protrusion 641 on its outer circumferential surface. The shear plug 54 has a first recess 542 on its inner circumferential surface 511. The first recess 542 is recessed from the inner circumferential surface 511. The first protrusion 641 fits into the first recess 542. The first protrusion 641 and the first recess 542 are continuous in the circumferential direction of the spacer 16 and are annular. The outer diameter d2 of the first protrusion 641 (see FIG. 4) is larger than the inner diameter d1 of the inner circumferential surface 511 of the through hole 51 (portion other than the recess 542) (d2>d1).

[0051] The wall portion 62 of the spacer 16 (see FIG. 5) has a second protrusion 642 on its outer circumferential side. The shear plug 54 has a second recess 543 on its inner circumferential surface 511. The second recess 543 is recessed from the inner circumferential surface 511. The second protrusion 642 fits into the second recess 543. An outer diameter D3 (of a circumscribing circle) of the second protrusion 642 is larger than the inner diameter d1 of the through hole 51 (D3>d1).

[0052] According to such a configuration of the first convex portion 641 and the second convex portion 642, although the spacer 16 is made of rubber and is elastically deformable, it is possible to prevent the spacer 16 from falling off the cover 13.

[0053] [Assembly of torque limiter 10] The torque limiter 10 of this embodiment is assembled in the following procedure. 2, a pin (not shown) is inserted into the pin hole 56 and the positioning hole 38. The shear valve 14 is attached in a slightly loose state by screwing into the first mounting hole 33 through the through hole 51. The coupler 17 is attached in a slightly loose state by screwing into the second mounting hole 36 through the coupler hole 55. A lubricating device (not shown) is connected to the coupler 17. A predetermined amount of oil is supplied through the coupler 17 and sealed in the hydraulic expansion chamber 34 (see FIG. 1). The hydraulic pressure of the sealed oil elastically deforms the inner periphery of the second cylindrical portion 32 and the first cylindrical portion 31, reducing the diameters of the inner periphery 321 of the second cylindrical portion 32 and the inner periphery 311 of the first cylindrical portion 31. The inner periphery 311 is pressed against the outer periphery 211 of the shaft member 11, and the shaft member 11 and the cylindrical member 12 are frictionally coupled together.

[0054] The shear valve 14 is further tightened and securely fixed in the mounting hole 33 (see FIG. 3). The spacer 16 is mounted in the through hole 51 of the shear plug 54. At this time, the claw portion 61 is elastically deformed. The pin is removed. A storage space 20 is provided between the inner peripheral surface 132 of the cover 13 and the outer peripheral surface 322 of the tubular member 12. A part 171 of the coupler 17 is located in the storage space 20 as a part of a part attached to the tubular member 12 and protruding from the outer peripheral surface 322 of the tubular member 12. Furthermore, the fastening working portion 43 of the shear valve 14 is located in the storage space 20. With the above, the assembly of the torque limiter 10 is completed.

[0055] [Function of Torque Limiter 10] As described above (see FIG. 1), the first cylindrical portion 31, which is the inner peripheral portion of the cylindrical member 12, elastically deforms toward the shaft member 11 due to the hydraulic pressure applied to the hydraulic expansion chamber 34. As a result, when a torque equal to or less than a predetermined value (low torque) acts on the torque limiter 10 (between the cylindrical member 12 and the shaft member 11), the cylindrical member 12 and the shaft member 11 rotate together due to a frictional force (frictional engagement) generated between the cylindrical member 12 and the shaft member 11, and the torque limiter 10 transmits torque.

[0056] When a torque (high torque) exceeding the predetermined value acts on the torque limiter 10, the cylindrical member 12 and the shaft member 11 rotate relative to each other (slip) against the frictional force. Then, the head 42 of the shear valve 14 is cut (sheared) by a part (shear plug 54) of the cover 13 fixed to the shaft member 11. Then, the hydraulic pressure in the hydraulic expansion chamber 34 is released in the tube 45 of the shear valve 14. Then, the frictional engagement is released, the cylindrical member 12 and the shaft member 11 rotate relative to each other, and the torque transmission is interrupted.

[0057] In this way, if an overload (overtorque) occurs between the shaft member 11 and the cylindrical member 12, the transmission of the overload (overtorque) is blocked. Although not shown, the torque limiter 10 is disposed in the middle of the power transmission path of a device or machine, thereby making it possible to protect the device or machine from overtorque.

[0058] [Torque limiter 10 of this embodiment] The torque limiter 10 of this embodiment has an axial member 11, a tubular member 12 located radially outward of the axial member 11, a cover 13 located on the outer periphery of the tubular member 12 and fixed to the axial member 11, and a shear valve 14 attached to the tubular member 12. The tubular member 12 has a hydraulic expansion chamber 34 provided therein, a hydraulic passage 35 extending from the hydraulic expansion chamber 34 to the outer circumferential side of the tubular member 12, and a first mounting hole 33 connected to the hydraulic passage 35 and opening at the outer circumferential surface 322 of the tubular member 12.

[0059] The shear valve 14 (see FIGS. 2 and 3) has a main body 41 attached to the first attachment hole 33, a head 42 having a portion (flange portion 422) located within the range of the through hole 51 of the cover 13, and a fastening working portion 43 located between the main body 41 and the head 42. A storage space 20 is provided between the inner surface (inner circumferential surface 132) of the cover 13 and the outer circumferential surface 322 of the tubular member 12. A part of a part attached to the tubular member 12 and protruding from the outer circumferential surface 322 is located in the storage space 20. In this embodiment, the part is a coupler 17, and the shear valve 14 has the head 42 cut off.

[0060] According to the torque limiter 10 of this embodiment, the frictional engagement is released when a high torque is applied. When the cylindrical member 12 and the shaft member 11 rotate relatively to each other, the storage space 20 makes it possible to prevent interference between a part of the parts and the cover 13. In this way, even if there is a part protruding from the outer circumferential surface 322 of the cylindrical member 12, the torque limiter 10 can function.

[0061] The storage space 20 has a shape that follows the cylindrical outer peripheral surface 322 of the tubular member 12. More specifically, since the cover 13 has a cylindrical shape, the storage space 20 is an annular space formed between the inner peripheral surface 132 of the cover 13 and the outer peripheral surface 322 of the tubular member 12.

[0062] 2, the fastening working portion 43 of the shear valve 14 is located in the storage space 20, which is radially outward from the outer circumferential surface 322 of the tubular member 12 and radially inward from the inner surface (inner circumferential surface 132) of the cover 13. The fastening working portion 43 is located so as to protrude radially outward from the outer circumferential surface 322 of the tubular member 12. Therefore, when removing the shear valve 14 from the mounting hole 33 after the head 42 has been cut off, a tool can be easily brought close to the fastening working portion 43. As a result, the operation of removing the used shear valve 14 is facilitated. When removing the shear valve 14, the covering member 15 and the spacer 16 are removed.

[0063] The head 42 of the shear valve 14 has an extension 421 extending from the fastening working portion 43 , and a flange 422 protruding from the extension 421 in the circumferential direction of the tubular member 12 . Since a storage space 20 is provided between the cover 13 and the tubular member 12, the head 42 of the cut shear valve 14 may enter the storage space 20 and become pinched between the cover 13 and the tubular member 12, which may adversely affect the operation of the torque limiter 10.

[0064] Therefore, in this embodiment, the torque limiter 10 has a covering member 15 that is attached to the outer periphery of the cover 13 and covers the through hole 51, and a spacer 16 that is attached to the through hole 51. The spacer 16 (see Figs. 4 and 5) has an annular claw portion 61. The claw portion 61 is located between the flange portion 422 and the fastening working portion 43, and protrudes toward the extension portion 421 side. The inner diameter (D2) of the claw portion 61 is smaller (D2) than the outer diameter D1 of the flange portion 422. <D1)。

[0065] According to the covering member 15 and the spacer 16, the cut head 42 is held between the covering member 15 and the claw portion 61 of the spacer 16, and is prevented from entering the storage space 20. Damage to the cover 13 and the tubular member 12 by the cut head 42 is prevented. The cut head 42 is held between the covering member 15 and the claw portion 61 of the spacer 16, which facilitates removal of the head 42. The spacer 16 improves the workability of restoring the torque limiter 10.

[0066] A portion 171 of the coupler 17 is located in a storage space 20 that is radially outward from an outer circumferential surface 322 of the tubular member 12 and radially inward from an inner surface (inner circumferential surface 132) of the cover 13. The portion 171 of the coupler 17 protrudes from the outer circumferential surface 322 of the tubular member 12, but is located within the radial range of the storage space 20. The presence of the storage space 20 prevents interference between the portion 171 of the coupler 17 and the cover 13 when the tubular member 12 and the shaft member 11 rotate relative to each other.

[0067] If the coupler 17 becomes larger or longer, there is a possibility that the second mounting hole 36 for mounting the coupler 17 will become deeper. If the second mounting hole 36 becomes deeper, it will be closer to the first mounting hole 33, and the stress in the vicinity of the first mounting hole 33 will increase, which may cause a weak point in terms of strength. Therefore, in the present embodiment (see Figs. 2 and 3), the central axis C1 of the second mounting hole 36 is inclined with respect to the radial direction of the tubular member 12. For this reason, although not shown, the second mounting hole 36 does not need to be formed deep in the radial direction of the tubular member 12, compared to a case in which the central axis C1 of the second mounting hole 36 coincides with the radial direction of the tubular member 12.

[0068] In this embodiment (see FIG. 2), the cover 13 has a cover body 52 fixed to the shaft member 11, and a ring-shaped shear plug 54. The shear plug 54 is detachably attached to a secondary through hole 53 provided in the cover body 52. ​​A central hole of the shear plug 54 becomes the through hole 51 in which the head 42 of the shear valve 14 is located. The head 42 of the shear valve 14 comes into contact with and is cut off by the central hole (through hole 51) of the shear plug 54. Even if the shear plug 54 is damaged through repeated use, it is sufficient to replace the shear plug 54 without replacing the cover body 52. Furthermore, by removing the shear plug 54, the opening in the cover 13 becomes wider. If readjustment is performed after the torque limiter 10 is assembled, by removing the shear plug 54, access to the shear valve 14 becomes easier.

[0069] 〔others〕 In the torque limiter 10 of the above embodiment, the four shear valves 14 are arranged at equal intervals in the circumferential direction, but this is not limiting. The number and arrangement of the shear valves 14 can be changed.

[0070] The embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the above-described embodiments, but includes all modifications within the scope of the equivalents of the configurations described in the claims. [Explanation of symbols]

[0071] 10 Torque limiter 11 Shaft member 12 Cylindrical member 13 Cover 14 Shear valve 15 Covering material 16 Spacer 17 Coupler 20 Storage Space 33 Mounting hole 34 Hydraulic expansion chamber 35 Hydraulic passage 36 Second mounting hole 41 Main body 42 Head 43 Fastening Work Section 51 Through hole 52 Cover body 53 Sub-through hole 54 Sharp Plug 61 Claw part 62 Wall 63 Opening 132 Inner peripheral surface (inner surface) 171 Part of the Kapla 322 Outer surface 323 Outer periphery 421 Extension 422 Tsuba

Claims

1. A shaft member; a cylindrical member located radially outward of the shaft member; a cover located on an outer circumferential side of the cylindrical member and fixed to the shaft member; a shear valve attached to the cylindrical member; having The cylindrical member is a hydraulic expansion chamber provided inside the cylindrical member; a hydraulic passage extending from the hydraulic expansion chamber to an outer circumferential side of the cylindrical member; a mounting hole that is connected to the hydraulic passage and opens on an outer circumferential surface of the cylindrical member; having The shear valve is A main body portion attached to the mounting hole; a head portion having a portion positioned within a range of a through hole of the cover; a fastening portion located between the body portion and the head portion and used when installing and removing the shear valve; having A storage space is provided between the inner surface of the cover and the outer circumferential surface of the tubular member, in which a part of the part attached to the tubular member and protruding from the outer circumferential surface of the tubular member is located. Torque limiter.

2. The storage space has a shape that conforms to the cylindrical outer circumferential surface of the tubular member.

2. The torque limiter according to claim 1.

3. The fastening portion is located in the storage space, the fastening portion being radially outward from an outer circumferential surface of the cylindrical member and radially inward from an inner surface of the cover. The torque limiter according to claim 1 or 2.

4. a covering member attached to an outer circumferential side of the cover and covering the through hole; A spacer attached to the through hole; having the head portion has an extension portion extending radially outward from the fastening working portion of the tubular member, and a flange portion protruding from the extension portion in a circumferential direction of the tubular member, the spacer has an annular claw portion located between the flange portion and the fastening working portion and protruding toward the extension portion, The inner peripheral contour shape of the claw portion is smaller than the outer peripheral contour shape of the flange portion. The torque limiter according to claim 1 or 2.

5. a coupler attached to an outer periphery of the cylindrical member for supplying oil to the hydraulic expansion chamber; a portion of the coupler is located in the storage space, the portion being radially outward from an outer circumferential surface of the cylindrical member and radially inward from an inner surface of the cover; The torque limiter according to claim 1 or 2.

6. The spacer has a pair of wall portions that fit into the through hole, An opening portion is provided between the pair of wall portions to expose an inner circumferential surface of the through hole, The openings are located on both sides of the torque limiter in a circumferential direction. The torque limiter according to claim 4.

7. the tubular member has a second mounting hole opening in an outer circumferential surface of the tubular member for mounting the coupler; The central axis of the second mounting hole is inclined with respect to the radial direction of the tubular member. The torque limiter according to claim 5.

8. The cover includes a cover body fixed to the shaft member and a ring-shaped shear plug detachably attached to a secondary through hole provided in the cover body, 3. The torque limiter according to claim 1, wherein the shear plug has a central hole which serves as the through hole in which the head is located.

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