JP5644604B2 - Torque limiter - Google Patents

Description

  The present invention relates to a torque limiter.

  Conventional torque limiters include those described in Japanese Patent Application Laid-Open No. 2004- 211794 (Patent Document 1). This torque limiter includes a shaft member and a cylindrical member, and the cylindrical member expands the hydraulic expansion chamber by the oil pressure of the oil filled in the hydraulic expansion chamber inside thereof, thereby causing the hydraulic expansion chamber to expand in the radial direction. The inner peripheral engagement surface that overlaps with the outer peripheral engagement surface is pressed against the outer peripheral engagement surface of the shaft member. In this way, the inner peripheral engagement surface and the outer peripheral engagement surface are frictionally engaged.

  The shaft member includes a main shaft portion and a cylindrical outer peripheral shaft portion. The main shaft portion is rotationally driven by a motor. In addition, the outer peripheral engagement surface is formed on the outer periphery of the outer peripheral shaft portion. The outer peripheral shaft portion is fitted and fixed to the main shaft portion with a tightening margin, and rotates integrally with the main shaft portion. The outer peripheral engagement surface of the outer peripheral surface portion receives a radially outward force by fitting in a state where the main shaft portion and the outer peripheral shaft portion have a tightening allowance, and the inner peripheral engagement surface It is deformed to bulge to the side.

  In such a background, in order to increase the transmission torque, the dimension in the axial direction of the hydraulic expansion chamber may be made larger than the length of the main shaft portion as an existing (off-the-shelf product). In addition, the hydraulic expansion chamber may have a portion that does not overlap the main shaft portion in the radial direction even when the positions of the main shaft portion and the outer peripheral shaft portion are shifted due to space or the like.

  However, in such a case, the dimension of the hydraulic expansion chamber is independent of the length of the main shaft portion, and there is an advantage that the degree of freedom in setting the hydraulic expansion chamber is large. The outer peripheral engagement surface that is present is a portion that overlaps the main shaft portion in the radial direction and a portion that is not, and the external force acting on these two portions is different from each other, and the outer peripheral engagement that is a torque transmission surface There is a problem that the deformation of the surface becomes non-uniform in the axial direction. As a result, there is a problem that the value of the release torque is not constant and the transmission torque is not stable.

Japanese Patent Laid-Open No. 2004-21794

  Therefore, the problem of the present invention is that the dimension of the hydraulic passage can be determined regardless of the dimension of the power transmission shaft, the degree of freedom in setting the dimension of the hydraulic passage is great, and the deformation of the torque transmission surface is uneven in the axial direction. An object of the present invention is to provide a torque limiter that can suppress the variation in release torque.

In order to solve the above problems, the torque limiter of the present invention is
A shaft member having an outer peripheral engagement surface;
A cylindrical member having an inner peripheral engagement surface and a hydraulic passage for pressing the inner peripheral engagement surface against the outer peripheral engagement surface, and externally fitting to the shaft member;
The shaft member is
A cylindrical engagement portion having an outer peripheral engagement surface formed on an outer periphery and an inner peripheral surface overlapping the hydraulic passage in a radial direction of the cylindrical member;
A power transmission shaft having an outer peripheral surface fitted inside the inner peripheral surface of the cylinder engaging portion with a tightening margin, the outer peripheral surface overlapping the hydraulic passage in the radial direction;
The power transmission shaft is located on one side in the axial direction, and has an outer peripheral surface that fits with a tight margin on the inner peripheral surface of the cylinder engaging portion, and the outer peripheral surface is connected to the hydraulic passage. It has the engagement surface deformation | transformation equalization part overlapped in the said radial direction, It is characterized by the above-mentioned.

  According to the present invention, it is sufficient that the outer peripheral surface of the power transmission shaft fitted in a state where the inner peripheral surface of the cylinder engaging portion has a tightening margin overlaps only a part of the hydraulic passage in the radial direction. Even if the transmission shaft is already installed (off-the-shelf product) and its length cannot be increased, the hydraulic passage can be enlarged regardless of the length of the power transmission shaft, and the release torque value can be increased. can do. That is, the axial dimension of the hydraulic passage can be set regardless of the axial dimension of the power transmission shaft, and the degree of freedom in setting the dimension of the hydraulic passage can be greatly increased.

  Further, according to the present invention, the outer peripheral surface of the engaging surface deformation uniformizing portion is fitted in the state where the inner peripheral surface of the tube engaging portion has a tightening margin in a state where the outer peripheral surface overlaps the hydraulic passage in the radial direction. Therefore, it is possible to alleviate unevenness of deformation between the portion of the outer peripheral engagement surface that is radially overlapped with the outer peripheral surface of the power transmission shaft and the portion that is not based on the inner fitting of the power transmission shaft. it can. That is, the cylindrical engagement is caused by the outward deformation in the radial direction of the outer peripheral engagement portion based on the inner fit with the tightening margin of the engagement surface deformation uniformizing portion on the inner peripheral surface of the cylindrical engagement portion. The unevenness in the axial position of the outer peripheral engagement surface based on the internal fit with the tightening margin of the power transmission shaft to the inner peripheral surface of the portion can be alleviated. Therefore, although the axial dimension of the hydraulic passage can be set independently of the axial dimension of the power transmission shaft, and the degree of freedom in setting the dimension of the hydraulic passage can be greatly increased, The deformation of the mating surface and the inner peripheral engagement surface) can be made uniform and the release torque variation can be suppressed.

  According to the torque limiter of the present invention, it is only necessary that the outer peripheral surface of the power transmission shaft fitted into the inner peripheral surface of the cylinder engaging portion overlaps only a part of the hydraulic passage in the radial direction. Even if it is an existing (off-the-shelf) product and its length cannot be increased, the hydraulic passage can be enlarged regardless of the length of the power transmission shaft, and the release torque value can be increased. it can. In addition, the axial dimension of the hydraulic passage can be set regardless of the axial dimension of the power transmission shaft, and the degree of freedom in setting the dimension of the hydraulic passage can be greatly increased.

  Further, according to the torque limiter of the present invention, the outer peripheral engagement surface based on the inner fit of the shaft transmission member is deformed by the deformation of the outer peripheral engagement portion based on the inner fit of the engagement surface deformation uniformizing portion to the cylinder engaging portion. Unevenness of deformation can be reduced. Therefore, the outer peripheral engagement surface can be prevented from being deformed non-uniformly at the position in the axial direction, so that the deformation of the torque transmission surface can be made closer to uniform, and variation in release torque can be suppressed. it can.

It is a schematic cross section of the axial direction of the torque limiter of one Embodiment of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view in the axial direction of a torque limiter according to an embodiment of the present invention.

  The torque limiter includes a shaft member 1, a cylindrical member 2, a shear valve 6, rolling bearings 17 and 18, and sealing members 50 and 51.

  The shaft member 1 includes a tube engaging portion 3, a power transmission shaft 4, and an engaging surface deformation uniformizing portion 5, and the tube engaging portion 3 includes a main body portion 8 and a locking portion 9. . The main body 8 has a substantially cylindrical outer peripheral engagement surface 20. On the other hand, the locking portion 9 has a substantially L-shaped cross section and protrudes from the outer surface of the main body portion 8. The tube engaging portion 3 has a substantially cylindrical inner peripheral surface 36, and the inner peripheral surface 36 overlaps the outer peripheral engaging surface 20 in the radial direction.

  The power transmission shaft 4 is rotated by a known power source such as a motor (not shown). The power transmission shaft 4 has an outer peripheral surface 46 that is fitted and fixed to the inner peripheral surface 36 of the cylinder engaging portion 3 by heat fitting. In other words, the outer peripheral surface 46 of the power transmission shaft 4 is fitted and fixed to the inner peripheral surface 36 of the cylinder engaging portion 3 with a tightening margin. The outer peripheral surface 46 of the power transmission shaft 4 is located apart from a part of the outer peripheral engagement surface 20 in the axial direction. The outer peripheral engagement surface 20 has a portion that does not overlap the outer peripheral surface 46 of the power transmission shaft 4 in the radial direction.

  The engaging surface deformation uniformizing portion 5 has an outer peripheral surface 47 that is fitted and fixed to the inner peripheral surface 36 of the tube engaging portion 3 by heat fitting. In other words, the outer peripheral surface 47 of the engaging surface deformation uniformizing portion 5 is fitted and fixed to the inner peripheral surface 36 of the tube engaging portion 3 with a tightening margin. The outer diameter of the outer peripheral surface 47 of the engagement surface deformation uniformizing portion 5 is substantially the same as the outer diameter of the outer peripheral surface 46 of the power transmission shaft 4. The allowable outer diameter of the outer peripheral surface of the engaging surface deformation uniformizing portion 5 will be described in detail later.

  The engagement surface deformation uniformizing portion 5 is located on one side in the axial direction of the power transmission shaft 4, and the outer peripheral surface 47 of the engagement surface deformation uniformizing portion 5 is the axial direction of the outer peripheral surface 46 of the power transmission shaft 4. Located on one side of The outer peripheral surface 47 of the engaging surface deformation uniformizing portion 5 is located apart from a part of the outer peripheral engaging surface 20 in the axial direction. The outer peripheral engagement surface 20 has a portion that does not overlap the outer peripheral surface 47 of the engagement surface deformation uniformizing portion 5 in the radial direction. The end surface on the insertion side in the axial direction of the power transmission shaft 4 to the inner peripheral surface 36 of the cylinder engaging portion 3 is in contact with one end surface in the axial direction of the engaging surface deformation uniformizing portion 5.

  The cylinder member 2 includes a first cylinder member 10 and a second cylinder member 11. The first cylinder member 10 has a substantially cylindrical inner peripheral engagement surface 21 that contacts the outer peripheral engagement surface 20 of the shaft member 1. The inner peripheral engagement surface 21 and the outer peripheral engagement surface 20 constitute a torque transmission surface. Between the outer peripheral engagement surface 20 of the shaft member 1 and the inner peripheral engagement surface 21 of the cylindrical member 2, a lubricating oil for preventing seizure of torque transmission surface such as traction oil or turbine oil is applied. .

  The second cylindrical member 11 has a substantially cylindrical inner peripheral surface 24 that abuts on the substantially cylindrical outer peripheral surface 23 of the first cylindrical member 10. The second cylinder member 11 has a shear valve mounting hole 30 and an annular hydraulic expansion chamber 26 as a hydraulic passage. The central axis of the hydraulic expansion chamber 26 substantially coincides with the central axis of the cylindrical member 2. The shear bubble mounting hole 30 extends in the radial direction of the cylindrical member 2, while the hydraulic expansion chamber 26 extends along the axial direction of the inner peripheral surface 24 of the second cylindrical member 11. Yes. As shown in FIG. 1, the first portion of the hydraulic expansion chamber 26 overlaps the outer peripheral surface 46 of the power transmission shaft 4 in the radial direction. The second portion of the hydraulic expansion chamber 26 overlaps the outer peripheral surface 47 of the engagement surface deformation uniformizing portion 5 in the radial direction in the radial direction. Each portion of the hydraulic expansion chamber 26 other than the portion that overlaps the chamfered portion at the shaft end of the power transmission shaft 4 in the radial direction is the outer peripheral surface 46 of the power transmission shaft 4 or the outer peripheral surface 47 of the engagement surface deformation uniformizing portion 5. Overlapping in the radial direction.

  The shear valve 6 is fitted in the shear valve mounting hole 30. In a state where the shear valve 6 is fitted in the shear valve mounting hole 30, one end portion of the shear valve 6 protrudes outward in the radial direction from the outer peripheral surface of the second cylindrical member 11.

  The locking portion 9 having a substantially L-shaped cross section has a radially extending portion 60 and an axially extending portion 61. The radially extending portion 60 extends in a substantially radial direction from the outer peripheral surface of the main body portion 8 and faces the axial end surface of the second tubular member 11 in the axial direction. The axially extending portion 61 is connected to the radially outer end of the radially extending portion 60 and extends in the axial direction along the outer peripheral surface of the second cylindrical member 11. doing. The one end portion of the shear valve 6 is locked by an axially extending portion 61 of the locking portion 9.

  The shear valve 6 has a tube 27 opened at only one end. The tube 27 extends substantially in the radial direction of the shaft member 1 in a state where the shear valve 6 is fitted in the shear valve mounting hole 30. Further, in a state where the shear valve 6 is fitted in the shear valve mounting hole 30, one end portion on the closed side of the tube 27 protrudes outward in the radial direction from the outer peripheral surface of the second cylinder member 11. The opening on the side opposite to the closed side of the tube 27 communicates with one end of the hydraulic expansion chamber 26. For this reason, the shear valve 6 side of the hydraulic expansion chamber 26 is a sealed space.

  The rolling bearings 17 and 18 are configured to rotatably support the shaft member 1 with respect to the cylindrical member 2 when the shaft member 1 rotates relative to the cylindrical member 2. The sealing members 50 and 51 are lubricants that prevent seizure between the outer peripheral engagement surface 20 and the inner peripheral engagement surface 21, and the lubricants that lubricate the rolling bearings 17 and 18 are exposed to the outside. Prevents leakage.

  In the above configuration, when a load less than a predetermined value is applied to the shaft member 1 or the cylindrical member 2 (the load within a range where torque is transmitted), the shaft member 1 or the cylindrical member 2 is injected into the hydraulic expansion chamber 26 via a coupler (not shown). With the sealed oil for hydraulic expansion, the diameter of the inner peripheral engagement surface 21 of the first cylindrical member 10 is reduced, and the inner peripheral engagement surface 21 is pressed against the outer peripheral engagement surface 20 of the shaft member 1 to 1 and the cylindrical member 2 are frictionally coupled to transmit torque between the shaft member 1 and the cylindrical member 2. In this way, the rotational power of the power transmission shaft 4 is transmitted to the first cylinder member 10 via the cylinder engaging portion 3.

  On the other hand, the shaft member 1 or the cylindrical member 2 is subjected to a load greater than a predetermined value (a load larger than the range in which torque is transmitted), and the outer peripheral engagement surface 20 of the shaft member 1 is within the first cylindrical member 10. When the position of the shaft member 1 and the cylinder member 2 about the axis changes due to slipping with respect to the circumferential engagement surface, the locking portion 9 cuts the one end portion of the shear valve 6 and the inside of the hydraulic expansion chamber 26 The oil for hydraulic expansion is discharged to the outside through a shear valve 6 having one end cut off. In this way, the pressing force of the inner peripheral engagement surface 21 of the first cylindrical member 10 against the outer peripheral engagement surface 20 of the shaft member 1 is eliminated, and the frictional coupling between the shaft member 1 and the cylindrical member 2 is released to generate torque. Is designed to cut off the transmission. In this way, when an overload occurs in the shaft member 1 or the cylindrical member 2, an expensive machine (for example, a reduction device of a rolling mill) that cuts off the transmission of torque and is connected to the torque limiter device. Is supposed to protect.

  According to the torque limiter of the above embodiment, the outer peripheral surface 46 of the power transmission shaft 4 fitted in a state where the inner peripheral surface 36 of the cylinder engaging portion 3 has a tightening margin is only part of the hydraulic expansion chamber 26. Since it is only necessary to overlap in the radial direction, even if the power transmission shaft 4 is already installed (off-the-shelf product) and the length thereof cannot be increased, the hydraulic expansion chamber 26 is independent of the length of the power transmission shaft 4. The release torque value can be increased. That is, the dimension in the axial direction of the hydraulic expansion chamber 26 can be set regardless of the dimension in the axial direction of the power transmission shaft 4, and the degree of freedom in setting the dimension of the hydraulic expansion chamber 26 can be greatly increased.

  Further, according to the torque limiter of the above-described embodiment, the cylinder engaging portion is formed in a state where the outer peripheral surface 47 of the engaging surface deformation uniformizing portion 5 is overlapped with a portion other than the part of the hydraulic expansion chamber 26 in the radial direction. Since the inner peripheral surface 36 of the power transmission shaft 4 is fitted with a tightening allowance, the outer peripheral surface 46 of the power transmission shaft 4 in the outer peripheral engagement surface 20 based on the inner fitting of the power transmission shaft 4 in the radial direction. It is possible to alleviate unevenness of deformation between the overlapping portion and the other portion. That is, the outer peripheral engagement surface 20 is deformed outwardly in the radial direction based on the inner fit with the tightening margin of the engagement surface deformation uniformizing portion 5 on the inner peripheral surface 36 of the cylinder engaging portion 3. Thus, the non-uniformity in the axial position of the outer peripheral engagement surface 20 based on the inner fit with the tightening allowance of the power transmission shaft 4 to the inner peripheral surface 36 of the cylinder engaging portion 3 is alleviated. Can do. Therefore, although the dimension in the axial direction of the hydraulic expansion chamber 26 can be set regardless of the dimension in the axial direction of the power transmission shaft 4, the degree of freedom in setting the dimension of the hydraulic expansion chamber 26 can be greatly increased. The deformation of the torque transmission surface can be made close to uniform, and variation in release torque can be suppressed.

  In the torque limiter of the above embodiment, the outer diameter of the outer peripheral surface of the power transmission shaft 4 that is fitted and fixed in a state where the inner peripheral surface of the cylinder engaging portion 3 has a tightening margin, and the cylinder engaging portion The outer diameter of the outer peripheral surface of the engaging surface deformation uniformizing portion 5 that is fitted and fixed in a state having a tightening margin on the inner peripheral surface of 3 is substantially the same.

  However, according to the present invention, the outer diameter of the outer peripheral surface of the power transmission shaft that is fitted and fixed with the tightening margin on the inner peripheral surface of the tube engaging portion and the inner peripheral surface of the tube engaging portion are tightened. The outer diameter of the outer peripheral surface of the engaging surface deformation uniformizing portion that is fitted and fixed in a state having a margin is that the error of the actual release torque value with respect to the desired release torque value is within an allowable range by those skilled in the art. It may be different within the range considered.

  Further, according to the present invention, the outer diameter of the outer peripheral surface of the power transmission shaft that is fitted and fixed with the tightening margin on the inner peripheral surface of the cylinder engaging portion, and the inner peripheral surface of the cylinder engaging portion are tightened. The outer diameter of the outer peripheral surface of the engaging surface deformation uniformizing portion that is fitted and fixed in a state having a margin is that the skilled person knows that the deformation of the outer peripheral engaging surface is the axial position of the outer peripheral engaging surface. Regardless of whether or not it is uniform, it may be different.

  Further, in the present invention, the outer diameter of the outer peripheral surface of the engagement surface deformation uniformizing portion is determined by the internal fitting in a state having a tightening margin of the engagement surface deformation uniformizing portion to the inner peripheral surface of the cylinder engaging portion. In comparison with the case where the inner fitting is not performed, the unevenness of the deformation of the outer peripheral engaging surface based on the inner fitting with the tightening margin of the power transmission shaft to the inner peripheral surface of the cylinder engaging portion is alleviated. Any value may be used as long as it is within the range. This is because, in this case, it is clear that the operational effect due to the internal fitting of the engaging surface deformation uniformizing portion appears.

  In the torque limiter of the above embodiment, the cylinder member 2 is sealed with the first cylinder member 10 having the inner peripheral engagement surface 21 that contacts the outer peripheral engagement surface 20 of the shaft member 1 and oil for hydraulic expansion. And the second cylinder member 11 having the hydraulic expansion chamber 26 to be configured. However, in this invention, the cylindrical member may be an integrated cylindrical member having an inner peripheral surface that contacts the outer peripheral surface of the shaft member and a hydraulic passage that encloses oil for hydraulic expansion.

  Further, in the torque limiter of the above embodiment, the outer peripheral surface 46 of the power transmission shaft 4 is fitted into the inner peripheral surface of the cylinder engaging portion 3 with a tightening margin, and the engaging surface deformation uniformizing portion 5 The outer peripheral surface 47 is fitted into the inner peripheral surface of the tube engaging portion 3 with a tightening margin, but the inner fitting with these tightening margins is realized by, for example, cold fitting, shrink fitting, press fitting, or the like. Can.

  Further, in the torque limiter of the above embodiment, as shown in FIG. 1, the cylinder engaging portion 3 is disposed on the end surface 70 on the opposite side to the power transmission shaft 4 side in the axial direction of the engaging surface deformation uniformizing portion 5. It has a structure having a stepped portion 71 that abuts and the tube engaging portion 3 extending in the axial direction and having a hole having a bottom. However, in the present invention, the cylinder engaging portion does not have to have a portion with which the end surface of the engaging surface deformation uniformizing portion opposite to the axial power transmission shaft side comes into contact. The hole having may be a through hole extending in the axial direction. In addition, as in the above-described embodiment, when the cylinder engaging portion has a step portion that contacts the end surface opposite to the axial power transmission shaft side of the engaging surface deformation uniformizing portion, the engaging surface deformation is uniform. It is preferable that the control portion can be positioned in the axial direction.

  In the torque limiter of the above embodiment, the axial end surface of the power transmission shaft 4 and the axial end surface of the engagement surface deformation uniformizing portion 5 are in contact with each other. Further, the engaging surface deformation uniformizing portion may be opposed to the axial direction at an interval. This modification may occur when there is a dimensional error of each member. In addition, it is preferable that the end face in the axial direction of the power transmission shaft 4 and the end face in the axial direction of the engagement surface deformation uniformizing portion 5 are in contact with each other because it is easy to realize uniform deformation of the torque transmission surface. Needless to say.

  Further, in the torque limiter of the above embodiment, the power transmission shaft 4 is driven by a power source such as a motor so that power is transmitted from the shaft member 1 to the tube member 2. The member side may be rotationally driven by a power source such as a motor so that power is transmitted from the cylindrical member to the shaft member.

  Further, in the torque limiter of the above embodiment, each part of the hydraulic expansion chamber 26 overlaps either the power transmission shaft 4 or the engagement surface deformation uniformizing portion 5 in the radial direction. The passage may have a portion that does not overlap the power transmission shaft in the radial direction and also does not overlap in the radial direction in the engagement surface deformation uniformizing portion. In addition, in order to make the deformation of the torque transmission surface uniform regardless of the position in the axial direction, each part of the hydraulic expansion chamber is arranged in the radial direction on either the power transmission shaft or the engagement surface deformation uniformizing portion. It goes without saying that it is preferable to overlap with. More specifically, each portion of the hydraulic expansion chamber overlaps either the power transmission shaft or the engagement surface deformation uniformizing portion in the radial direction, and the hydraulic expansion chamber has uniform engagement surface deformation. Needless to say, it is more preferable not to overlap the chamfered portion of the shaft end opposite to the power transmission shaft side in the axial direction of the portion. This is because the chamfered portion is located at an interval on the inner peripheral surface of the tube engaging portion.

  In the torque limiter of the above embodiment, the hydraulic expansion chamber 26 is annular. However, in the present invention, the hydraulic passage may not be annular.

  In the above embodiment, it goes without saying that ball bearings or roller bearings can be adopted as the rolling bearings 17 and 18. The torque limiter of the present invention can be used, for example, in a rolling mill or a crusher, and can be used as an alternative to a shear pin type joint. Needless to say, the torque limiter according to the present invention can be used to prevent destruction of any machine as long as the machine can be broken (failed) due to overload.

  In the torque limiter according to the embodiment, JISB0401 (1999) is an interference fit between the inner peripheral surface of the cylinder engaging portion and the outer peripheral surface of the power transmission shaft and the outer peripheral surface of the engaging surface deformation uniformizing portion. The fitting specified in n5 and n6 can be applied. However, if the fitting between the inner peripheral surface of the cylinder engaging portion and the outer peripheral surface of the power transmission shaft and the outer peripheral surface of the engaging surface deformation uniformizing portion is a fitting with a tightening margin, the fitting is performed as described above. Of course, any fitting can be applied.

DESCRIPTION OF SYMBOLS 1 Shaft member 2 Cylinder member 3 Cylinder engagement part 4 Power transmission shaft 5 Engagement surface deformation | transformation equalization part 20 Outer peripheral engagement surface 21 Inner peripheral engagement surface 26 Hydraulic expansion chamber 36 Inner peripheral surface 46 of cylindrical engagement part 46 Power transmission Outer peripheral surface of shaft 47 Outer peripheral surface of engaging surface deformation uniformizing portion

Claims (1)

A shaft member having an outer peripheral engagement surface;
A cylindrical member having an inner peripheral engagement surface and a hydraulic passage for pressing the inner peripheral engagement surface against the outer peripheral engagement surface, and externally fitting to the shaft member;
The shaft member is
A cylindrical engagement portion having an outer peripheral engagement surface formed on the outer periphery, and an inner peripheral surface overlapping the hydraulic passage in a radial direction of the cylindrical member;
A power transmission shaft having an outer peripheral surface fitted inside the inner peripheral surface of the cylinder engaging portion with a tightening margin, the outer peripheral surface overlapping the hydraulic passage in the radial direction;
The power transmission shaft is located on one side in the axial direction, and has an outer peripheral surface that fits with a tight margin on the inner peripheral surface of the cylinder engaging portion, and the outer peripheral surface is connected to the hydraulic passage. A torque limiter having an engagement surface deformation uniformizing portion overlapping in the radial direction.

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