JP2018017300A - Disc brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disc brake capable of suppressing occurrence of noise in operation of parking brake.SOLUTION: A disc brake 1 is configured such that mutual contact surfaces along a circumferential direction between each projection part 74 provided on an outer peripheral surface of an internal gear 61 and an engagement groove 31D provided at a first housing part 31 are inclined to an axial direction of the internal gear 61. As the result, an area of each contact surface can be formed larger than conventional ones, and surface pressure of each contact surface can be reduced. Consequently, occurrence of noise in operation of parking brake can be suppressed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a disc brake used for braking a vehicle.

  Some conventional disc brakes include a planetary gear reduction mechanism that increases the rotational force from a motor and transmits it to a piston drive mechanism when a parking brake or the like is operated. The internal gear of the planetary gear speed reduction mechanism is supported by the first housing portion of the housing so as not to be relatively rotatable (see Patent Document 1).

JP 2014-29193 A

  Therefore, in the invention of Patent Document 1, as a structure for supporting the internal gear of the planetary gear speed reduction mechanism on the first housing portion so as not to be relatively rotatable, a plurality of protrusions made of a substantially rectangular parallelepiped are provided on the outer peripheral surface of the internal gear. It is assumed that the first housing portion is provided with an engagement groove corresponding to each projection portion, and each projection portion of the internal gear is engaged with each engagement groove of the first housing portion. However, in this support structure, since there is a clearance along the circumferential direction between each protrusion of the internal gear and each engagement groove of the first housing portion, when the planetary gear reduction mechanism is operated, the internal gear is It will rotate slightly by the clearance. And when each projection part of an internal gear and the inner wall face of each engaging groove collide, the surface pressure provided to a mutual contact surface is large, and there exists a possibility that a collision noise (abnormal noise) may generate | occur | produce.

  Then, an object of this invention is to provide the disc brake which can suppress generation | occurrence | production of unusual noise at the time of operation | movement of a parking brake etc.

  As means for solving the above-described problems, the present invention includes a piston that presses one of a pair of pads disposed on both sides in the axial direction of the rotor across the rotor against the rotor, and the piston is movably accommodated. And a caliper main body having a cylinder in which the piston propulsion mechanism for propelling the piston is housed, a motor provided in the caliper main body, and a speed reduction mechanism for increasing the rotational force from the motor and transmitting it to the piston propulsion mechanism And a support member attached to the caliper main body and supporting the speed reduction mechanism. The planetary gear speed reduction mechanism is provided as the speed reduction mechanism, and the planetary gear speed reduction mechanism is relatively non-rotatable to the support member. A plurality of protrusions facing radially outward at intervals in the circumferential direction on the outer peripheral surface of the internal gear. The support member is formed with a plurality of engaging grooves with which the protrusions are respectively engaged, and contact surfaces along the circumferential direction of the protrusions and the engaging grooves are formed on the interface. It is formed so as to be inclined with respect to the axial direction of the null gear or the radial direction in which the protruding portion protrudes.

  According to the disc brake of the present invention, it is possible to suppress the generation of abnormal noise during operation of a parking brake or the like.

Sectional drawing which shows the disc brake which concerns on this embodiment. The exploded perspective view in a housing. The exploded perspective view in a housing. The perspective view of the projection part provided in the internal gear. The perspective view of the locking groove provided in the 1st housing part. The expanded sectional view of a piston propulsion mechanism. The disassembled perspective view of a piston propulsion mechanism. The principal part perspective view of the disc brake which concerns on other embodiment. The principal part perspective view of the disc brake which concerns on other embodiment. The perspective view of the projection part provided in the internal gear based on other embodiment. The perspective view of the latching groove | channel provided in the 1st housing part based on other embodiment.

Hereinafter, the present embodiment will be described in detail with reference to FIGS.
As shown in FIG. 1, the disc brake 1 includes a pair of inner brake pads 2 and outer brake pads 3 disposed on both sides in the axial direction with a disc rotor D attached to a rotating portion of the vehicle, and a caliper 4. And are provided. The disc brake 1 is configured as a caliper floating type. The pair of inner brake pads 2 and outer brake pads 3 and the caliper 4 are supported by a bracket 5 fixed to a non-rotating portion such as a knuckle of the vehicle so as to be movable in the axial direction of the disc rotor D. In the following description, for convenience of explanation, the right side in FIG. 1 will be described as one end side and the left side as the other end side as appropriate.

  The caliper body 6 that is the main body of the caliper 4 includes a cylinder portion 7 that is disposed on the base end side facing the inner brake pad 2 on the vehicle inner side, and a claw that is disposed on the distal end side facing the outer brake pad 3 on the vehicle outer side. Part 8. The cylinder portion 7 is formed with a bottomed cylinder 15 that is a large-diameter opening portion 9 </ b> A that is open on the inner brake pad 2 side and is closed on the opposite side by a bottom wall 11 having a hole 10. On the bottom wall 11 side in the cylinder 15, a small-diameter opening 9B that is continuous with the large-diameter opening 9A and has a smaller diameter than the large-diameter opening 9A is formed. The cylinder 15 has a piston seal 16 disposed on the inner peripheral surface of the large-diameter opening 9A.

  The piston 18 is formed in a bottomed cup shape including a bottom portion 19 and a cylindrical portion 20. The piston 18 is accommodated in the cylinder 15 so that the bottom portion 19 faces the inner brake pad 2. The piston 18 is housed in the large-diameter opening 9A of the cylinder 15 so as to be movable in the axial direction while being in contact with the piston seal 16. A space between the piston 18 and the bottom wall 11 of the cylinder 15 is defined by a piston seal 16 as a hydraulic chamber 21. The fluid pressure chamber 21 is supplied with fluid pressure from a fluid pressure source (not shown) such as a master cylinder or a fluid pressure control unit through a port (not shown) provided in the cylinder portion 7.

  A plurality of rotation restricting vertical grooves 22 (see FIG. 6) are formed on the inner peripheral surface of the piston 18 along the circumferential direction. A recess 25 is provided on the outer peripheral side of the other end surface of the bottom portion 19 of the piston 18 facing the inner brake pad 2. The concave portion 25 is engaged with a convex portion 26 formed on the back surface of the inner brake pad 2. By this engagement, the piston 18 is restricted so as not to rotate relative to the cylinder 15 and thus to the caliper body 6. Further, a dust boot 27 is interposed between the outer peripheral surface of the piston 18 on the bottom 19 side and the inner peripheral surface of the large-diameter opening 9 </ b> A of the cylinder 15 to prevent foreign matter from entering the cylinder 15. Yes.

  As shown in FIGS. 1 to 3, the housing 30 is attached to the bottom wall 11 side of the cylinder 15 of the caliper body 6. An opening 30 </ b> A is provided at one end of the housing 30. The opening 30A is airtightly closed by the cover 36. A seal member 37 is provided between the housing 30 and the cylinder portion 7. The inside of the housing 30 is kept airtight by the seal member 37. The housing 30 is integrally formed from a first housing part 31 and a first housing part 31 that accommodates a spur multi-stage reduction mechanism 44 and a planetary gear reduction mechanism 45 described later so as to cover the outer periphery of the bottom wall 11 of the cylinder 15. And a second housing portion 32 that houses the motor 200. As described above, the housing 30 is configured to accommodate the motor 200 arranged in line with the caliper body 6 by the bottomed cylindrical second housing portion 32.

  The first housing portion 31 is inserted with a housing chamber 31E that houses a flat-tooth multistage reduction mechanism 44 and a planetary gear reduction mechanism 45, which will be described later, together with the cover 36, and a polygonal shaft portion 81 of a base nut 75 of the piston propulsion mechanism 43, which will be described later. An opening 31A, an inner annular wall 31B protruding around the opening 31A, an outer annular wall 31C protruding radially from the inner annular wall 31B, and A plurality of engagement grooves 31D formed at intervals in the circumferential direction of the outer annular wall portion 31C. Referring also to FIG. 5, the pair of contact surfaces 31F and 31F facing each other along the circumferential direction of each engagement groove 31D is a pair of protrusions 74 provided on the internal gear 61 of the planetary gear reduction mechanism 45 described later. Similar to the contact surfaces 74 </ b> A and 74, the contact surfaces are inclined with respect to the axial direction of the first housing portion 31. The pair of contact surfaces 31F and 31F of the engagement groove 31D are inclined so as to be separated from each other toward the cover 36 side.

  The caliper body 6 includes a flat-tooth multistage reduction mechanism 44 and a planetary gear reduction mechanism 45 that increase the driving force of the motor 200, and a piston propulsion mechanism 43 that propels the piston 18 and holds the propelled piston 18 in a braking position. Is provided. The spur multi-stage speed reduction mechanism 44 and the planetary gear speed reduction mechanism 45 as the speed reduction mechanism are accommodated in an accommodation chamber 31 </ b> E in the first housing portion 31 of the housing 30.

  The spur multi-stage reduction mechanism 44 includes a pinion gear 46, a first reduction gear 47, a non-reduction spur gear 48, and a second reduction gear 49. The pinion gear 46 is formed in a cylindrical shape, and has a hole 50 that is press-fitted and fixed to the rotating shaft 201 of the motor 200, and a gear 51 that is formed on the outer periphery. The first reduction gear 47 is integrally formed with a large-diameter large gear 53 that meshes with the gear 51 of the pinion gear 46 and a small-diameter small gear 54 that extends from the large gear 53 in the axial direction. . The shaft 52 is integrally fixed to the first reduction gear 47. One end of the shaft 52 is rotatably supported by a support plate 59 adjacent to the cover 36, and the other end is rotatably supported by the holder 205.

  The small gear 54 of the first reduction gear 47 meshes with the non-reduction spur gear 48. The non-reducing spur gear 48 is rotatably supported by the shaft 55. One end of the shaft 55 is press-fitted and fixed to the support plate 59 close to the cover 36, and the other end is press-fitted and fixed to the holder 205. The second reduction gear 49 is integrally formed with a large-diameter large gear 56 that meshes with the non-reducing spur gear 48 and a small-diameter sun gear 57 that extends from the large gear 56 in the axial direction. The sun gear 57 is configured as a part of a planetary gear reduction mechanism 45 described later. A shaft 58 is rotatably supported by the second reduction gear 49. The shaft 58 is press-fitted and fixed to a support plate 59 provided at one end close to the cover 36. Further, an annular stopper portion 56 </ b> A that protrudes toward the planetary gear reduction mechanism 45 is formed on the annular wall portion of the large gear 56 of the second reduction gear 49.

  The planetary gear reduction mechanism 45 includes a sun gear 57 of the second reduction gear 49, a plurality (four in this embodiment) of planetary gears 60, an internal gear 61, and a carrier 62. Each planetary gear 60 has a gear 63 meshed with the sun gear 57 of the second reduction gear 49 and a hole 64 through which a pin 65 erected from the carrier 62 is rotatably inserted. The planetary gears 60 are arranged at equal intervals on the circumference of the carrier 62. An annular plate 66 is disposed on the other end side of each planetary gear 60.

  The carrier 62 is formed in a disk shape, and a polygonal hole 68 is formed at the substantially radial center. The outer diameter of the carrier 62 is substantially the same as the outer diameter of the revolution trajectory of each planetary gear 60. A plurality of pin holes 69 are formed on the outer peripheral side of the carrier 62 at intervals along the circumferential direction. A pin 65 is press-fitted and fixed in each pin hole 69. Each pin 65 is rotatably inserted into a hole 64 of each planetary gear 60. Then, the polygonal hole 68 of the carrier 62 and the polygonal shaft portion 81 of the base nut 75 of the piston propulsion mechanism 43 which will be described later are fitted together so that the rotational torque can be transmitted between the carrier 62 and the base nut 75. It has become.

  The internal gear 61 continuously extends radially from one end on the cover 36 side of the internal teeth 71 with which the gear 63 of each planetary gear 60 is engaged, and restricts the movement of each planetary gear 60 in the axial direction. And a cylindrical wall portion 73 extending from the inner teeth 71 toward the bottom wall 11 of the cylinder 15. Referring also to FIG. 4, a plurality of projecting portions 74 that are arranged at intervals in the circumferential direction are provided projecting radially outward on the other end side of the outer peripheral surface of the cylindrical wall portion 73. Each protrusion 74 is formed in a quadrangular prism shape. A pair of contact surfaces 74 </ b> A and 74 </ b> A along the circumferential direction of each protrusion 74 is inclined with respect to the axial direction of the internal gear 61. The pair of contact surfaces 74A and 74A are inclined so as to be separated from each other toward the cover 36 side.

  The internal gear 61 has a cylindrical wall portion 73 inserted into an annular space between the inner annular wall portion 31 </ b> B and the outer annular wall portion 31 </ b> C of the first housing portion 31. By being inserted into and engaged with each engaging groove 31 </ b> D of the first housing part 31, the first housing part 31 is supported in a non-rotatable manner. The housing 30 corresponds to a support member. Further, since the internal gear 61 is arranged so that the annular stopper portion 56A provided on the large gear 56 of the second reduction gear 49 abuts on the cover 36 side of the annular wall portion 72, the axial direction The first housing portion 31 is supported so as not to move.

  An annular plate 66 is disposed in the cylindrical wall portion 73 of the internal gear 61. The annular plate 66 is sandwiched between the other end surface of the inner teeth 71 of the internal gear 61 and the inner annular wall portion 31 </ b> B of the first housing portion 31. Thereby, each planetary gear 60 is arrange | positioned between the annular wall part 72 and the annular plate 66 of the internal gear 61, and the movement of an axial direction is controlled.

  The motor 200 is supported by a holder 205 disposed on the flange portion 202. The holder 205 is configured by integrally connecting a motor support portion 206 and a ring-shaped support portion 207. The motor support portion 206 is arranged between the first reduction gear 47 and the non-reduction spur gear 48 and the flange portion 202 of the motor 200 to support the motor 200. The ring-shaped support portion 207 is disposed around the internal gear 61 of the planetary gear reduction mechanism 45 so as to surround the internal gear 61. The motor support portion 206 is formed with a rotation shaft insertion hole 208 through which the pinion gear 46 press-fitted and fixed to the rotation shaft 201 of the motor 200 is inserted. A pair of terminal insertion holes through which the motor terminals 203 of the motor 200 are inserted are formed on both sides in the radial direction of the rotation shaft insertion hole 208. Harnesses 250 and 251 are connected to the motor terminals 203 of the motor 200, respectively.

  The motor support portion 206 of the holder 205 includes a holder-side first convex portion 211, a holder-side second convex portion 212, and a holder-side first portion on the opposite side of the planetary gear speed reduction mechanism 45 around the rotation shaft insertion hole 208. Three convex portions 213 are formed at intervals from each other. The holder-side first convex portion 211, the holder-side second convex portion 212, and the holder-side third convex portion 213 are cylindrical and project from the cover 36 side. Two fastening holes 216 are formed in the motor support portion 206. Each mounting bolt 215 passes through each through hole 202A of the flange portion 202 of the motor 200 and is fastened to the fastening hole 216 of the motor support portion 206, so that the motor 200 is supported by the motor support portion 206 of the holder 205. . The ring-shaped support portion 207 is disposed on each protrusion 74 so as to contact the outer peripheral surface of the internal gear 61 of the planetary gear reduction mechanism 45.

  Cylindrical support portions 217 and 217 are integrally formed at two locations on the holder 205 between the motor support portion 206 and the ring-shaped support portion 207. A support plate 59 is disposed on each cylindrical support portion 217, and each mounting bolt 218 is fastened to each cylindrical support portion 217 of the holder 205 via the support plate 59, so that the support plate 59 is mounted on the holder 205. Will be supported at intervals.

  On the inner surface of the cover 36, a cover-side first cylindrical portion 221, a cover-side second convex portion 222, and a cover-side third convex portion 223 are provided so as to protrude from each other at intervals. The cover-side first cylindrical portion 221, the cover-side second convex portion 222, and the cover-side third convex portion 223 are a holder-side first convex portion 211, a holder-side second convex portion 212, and a holder-side provided on the holder 205. Each is formed at a position facing the third convex portion 213. And the cover side 1st cylindrical part 221, the cover side 2nd convex part 222, the cover side 3rd convex part 223 of the cover 36, the holder side 1st convex part 211, the holder side 2nd convex part of the holder 205 A rubber 230, which is an elastic member, is interposed between 212 and the holder-side third convex portion 213.

  The rubber 230 is formed by integrating the first cup portion 231, the second cup portion 232, the third cup portion 233, and the opening side end portions of the first cup portion 231, the second cup portion 232, and the third cup portion 233. And a plate-like base portion 234 connected to each other. Then, the first cup portion 231 of the rubber 230 is fitted to the holder-side first convex portion 211 of the holder 205, the second cup portion 232 of the rubber 230 is fitted to the holder-side second convex portion 212 of the holder 205, The third cup portion 233 of the rubber 230 is fitted to the holder-side third convex portion 213 of the holder 205 so that the rubber 230 is unitized with the holder 205. Thereafter, the cover-side first cylindrical portion 221 of the cover 36 is fitted into the first cup portion 231 of the rubber 230, and the cover-side second convex portion 222 of the cover 36 is fitted to the second cup portion 232 of the rubber 230. In addition, the cover 36 is covered so that the cover side third convex portion 223 of the cover 36 contacts the third cup portion 233 of the rubber 230. Note that harnesses 250 and 251 extending from the motor terminals 203 of the motor 200 are disposed along the base portion 234 of the rubber 230.

  As shown in FIG. 2, in this embodiment, a plurality of types of rubbers 281, 282, and 283 different from the rubber 230 described above are provided in the housing 30. A U-shaped support section 280 is formed at the end of the holder 205 on the motor support section 206 side, and a U-shaped rubber section 281 is integrally disposed therein. Block-shaped rubbers 282 are respectively disposed between the outer peripheral surface at a position close to each cylindrical support portion 217 and the inner wall surface of the first housing portion 31 in the ring-shaped support portion 207 of the holder 205. A cylindrical rubber 283 is disposed between the main body side end portion of the motor 200 and the bottom wall portion of the second housing portion 32.

  In the present embodiment, in order to obtain the rotational force for propelling the piston 25, the spur multi-stage reduction mechanism 44 and the planetary gear reduction mechanism 45 are employed as the reduction mechanism that increases the driving force by the motor 200. You may comprise only the deceleration mechanism 45. FIG. Further, a speed reducer according to another known technique such as a cycloid speed reduction mechanism or a wave speed reducer may be combined with the planetary gear speed reduction mechanism 45.

Next, the piston propulsion mechanism 43 will be specifically described based on FIGS. 1, 6, and 7. In the following description, for convenience of explanation, the right side of FIGS. 1 and 6 is appropriately described as one end side and the left side is appropriately described as the other end side.
The piston propulsion mechanism 43 converts the rotational movement from the spur multi-stage reduction mechanism 44 and the planetary gear reduction mechanism 45, that is, rotation of the motor 200 into linear movement (hereinafter referred to as linear movement for convenience), and converts it into the piston 18. A thrust is applied to hold the piston 18 in the braking position. The piston propulsion mechanism 43 is screw-fitted to a base nut 75 that is rotatably supported by transmission of rotational movement from the spur multi-stage reduction mechanism 44 and the planetary gear reduction mechanism 45, and a female thread portion 97 of the base nut 75. The push rod 102 is rotatably and linearly supported by the rotation of the base nut 75, and is screwed to the push rod 102. The rotation of the push rod 102 causes the piston 18 to move in the axial direction. And a ball-and-ramp mechanism 127 for applying thrust. The piston propulsion mechanism 43 is accommodated between the cylinder 15 and the piston 18 of the caliper body 6.

  As shown in FIGS. 6 and 7, the base nut 75 includes a cylindrical portion 76 and a nut portion 77 provided integrally with the other end of the cylindrical portion 76. A washer 80 is disposed so as to contact the bottom wall 11 of the cylinder 15. The cylindrical portion 76 of the base nut 75 is inserted into each of the insertion hole 80 </ b> A of the washer 80 and the hole portion 10 provided in the bottom wall 11 of the cylinder 15. A polygonal shaft portion 81 is integrally connected to the tip of the cylindrical portion 76. The polygon shaft portion 81 is inserted into the opening 31 </ b> A of the first housing portion 31 and is fitted into the polygon hole 68 of the carrier 62. The nut portion 77 of the base nut 75 is formed in a bottomed cylindrical shape. The nut portion 77 includes a circular wall portion 82 and a cylindrical portion 83 projecting integrally from the other end surface of the circular wall portion 82. The outer peripheral surface of the circular wall portion 82 is close to the inner wall surface of the small-diameter opening 9B of the cylinder 15. A small-diameter circular wall 84 protrudes from the radial center of one end face of the circular wall 82. A cylindrical portion 76 projects from one end surface of the small-diameter circular wall portion 84 toward one end side. The outer diameter of the cylindrical portion 76 is formed smaller than the outer diameter of the cylindrical portion 83 of the nut portion 77.

  A thrust bearing 87 is disposed between the washer 80 and the circular wall portion 82 around the small-diameter circular wall portion 84 provided in the nut portion 77 of the base nut 75. The base nut 75 is rotatably supported by the bottom wall 11 of the cylinder 15 by a thrust bearing 87. A seal member 88 and a sleeve 89 are provided between the outer peripheral surface of the cylindrical portion 76 of the base nut 75 and the hole 10 of the bottom wall 11 of the cylinder 15. Thereby, the fluid tightness of the hydraulic chamber 21 is maintained. A retaining ring 90 is mounted in an annular groove provided between the cylindrical portion 76 of the base nut 75 and the polygonal shaft portion 81. By the retaining ring 90, the base nut 75 is restricted from moving in the axial direction toward the cylinder 15.

  The cylindrical portion 83 of the nut portion 77 of the base nut 75 includes a large diameter cylindrical portion 91 disposed on one end side and a small diameter cylindrical portion 92 disposed on the other end side. One end of the large-diameter cylindrical portion 91 is integrally connected to the circular wall portion 82. A plurality of through holes 95 extending in the radial direction are formed in the peripheral wall portion of the large diameter cylindrical portion 91. A plurality of through holes 95 are formed at intervals in the circumferential direction. A female thread portion 97 is formed on the inner peripheral surface of the small diameter cylindrical portion 92 of the nut portion 77. A plurality of locking grooves 98 are formed on the other end surface of the peripheral wall portion of the small diameter cylindrical portion 92 at intervals in the circumferential direction. In the present embodiment, four locking grooves 98 are formed.

  The distal end portion 100A of the first spring clutch 100 is fitted into one of the locking grooves 98 of the small diameter cylindrical portion 92 of the base nut 75. The first spring clutch 100 includes a distal end portion 100A facing outward in the radial direction and a coil portion 100B wound continuously from the distal end portion 100 in a single layer. And the front-end | tip part 100A of the 1st spring clutch 100 is fitted by either of each locking groove 98 of the small diameter cylindrical part 92 of the base nut 75, and the coil part 100B is the male thread part 103 of the push rod 102 mentioned later. It is wound around the other end. The first spring clutch 100 applies a rotational resistance torque in the rotational direction (the rotational direction at the time of release) when the push rod 102 moves toward the bottom wall 11 side of the cylinder 15 with respect to the base nut 75. The push rod 102 is configured to allow rotation in the rotation direction (rotation direction at the time of application) when the push rod 102 moves to the bottom 19 side of the piston 18 with respect to the base nut 75.

  One end side of the push rod 102 is inserted into the nut portion 77 of the base nut 75. On one end side of the push rod 102, a male screw portion 103 that is screwed into the female screw portion 97 of the small diameter cylindrical portion 92 of the base nut 75 is formed. The first screw fitting portion 105 between the male screw portion 103 of the push rod 102 and the female screw portion 97 of the small-diameter cylindrical portion 92 of the base nut 75 causes the base nut to move in the axial direction from the piston 18 to the push rod 102. In order not to rotate 75, the reverse efficiency is set to 0 or less, that is, it is configured as a screw fitting portion having a large irreversibility.

  On the other hand, on the other end side of the push rod 102, a male screw portion 104 that is screw-fitted to a female screw portion 162 provided on a rotary linear motion lamp 151 of a ball and ramp mechanism 127 described later is formed. Here again, the second screw fitting portion 106 between the male threaded portion 104 of the push rod 102 and the female threaded portion 162 provided on the rotary linear motion ramp 151 is used for the axial load from the piston 18 to the rotational linear motion ramp 151. In order to prevent the push rod 102 from rotating, the reverse efficiency of the push rod 102 becomes 0 or less, that is, the screw fitting portion has a large irreversibility.

  The push rod 102 is provided with a spline shaft 108 between a male screw portion 103 on one end side and a male screw portion 104 on the other end side. The outer diameter of the male screw portion 103 on one end side is formed larger than the outer diameter of the male screw portion 104 on the other end side. The outer diameter of the male screw portion 103 on one end side is formed larger than the outer diameter of the spline shaft 108. A small-diameter cylindrical portion 107 is continuously formed on the other end side from the male screw portion 104 of the push rod 102. The outer peripheral surface of the cylindrical portion 107 is knurled. A stopper member 172 is integrally fixed to the cylindrical portion 107 of the push rod 102 by press-fitting. The stopper member 172 defines a range of relative rotation of the rotary linear motion lamp 151 of the ball and ramp mechanism 127 described later with respect to the push rod 102. The other end surface of the cylindrical portion 107 of the push rod 102 faces the bottom portion 19 of the piston 18.

  The retainer 110 is supported between the outer peripheral surface of the small diameter cylindrical portion 92 of the cylindrical portion 84 constituting the nut portion 77 of the base nut 75 and the inner peripheral surface of the cylindrical portion 20 of the piston 18 so as to be movable in the axial direction. . The retainer 110 has an annular wall portion 111 on one end side, and is configured in a substantially cylindrical shape as a whole. A plurality of through holes 114 and 115 are formed in the outer peripheral wall of the retainer 110.

  Within the retainer 110, one end side washer 120, a coil spring 121, the other end side washer 122, a support plate 123, a second spring clutch 124, a rotating member 125, a thrust bearing 126, a ball and ramp mechanism 127, in order from one end side. A thrust bearing 128 and an annular pressing plate 129 are arranged. The one end side washer 120 is disposed so as to contact the other end surface of the annular wall portion 111 of the retainer 110.

  A coil spring 121 is interposed between the one end side washer 120 and the other end side washer 122. The coil spring 121 urges the one end side washer 120 and the other end side washer 122 in a direction to separate them. A plurality of locking grooves 132 having a predetermined depth are formed on the other end surface of the peripheral wall portion of the retainer 110 at intervals in the circumferential direction. Each locking groove 132 includes a narrow locking groove 133 positioned on one end side and a wide locking groove 134 positioned on the other end side. The locking groove 132 is formed in three places in this embodiment. At the other end of the retainer 110, a plurality of claw portions 136 are formed toward the bottom portion 19 of the piston 18. In the retainer 110, one end side washer 120, a coil spring 121, the other end side washer 122, a support plate 123, a second spring clutch 124, a rotating member 125, a thrust bearing 126, a ball and ramp mechanism 127, a thrust bearing 128, and an annular shape After the pressing plate 129 is accommodated, each of the claw portions 136 of the retainer 110 is folded toward the accommodating recess 171 of the annular pressing plate 129, which will be described later, so that the above-described many constituent members are integrally disposed in the retainer 110. Can be assembled.

  An annular support plate 123 is disposed so as to contact the other end surface of the other end washer 122. A plurality of protruding pieces 137 are provided on the outer peripheral surface of the support plate 123 at intervals along the circumferential direction. In the present embodiment, three protrusion pieces 137 are formed. The protrusions 137 of the support plate 123 are fitted into the narrow locking grooves 133 of the retainer 110 and the rotation restricting vertical grooves 22 provided on the inner peripheral surface of the piston 18, respectively. As a result, the retainer 110 is supported together with the one end side washer 120, the coil spring 121, the other end side washer 122, and the support plate 123 so as not to rotate relative to the piston 18 and to be relatively movable in the axial direction.

  In the retainer 110, the rotation member 125 is rotatably supported on the other end side of the support plate 123. The rotating member 125 includes a large-diameter annular portion 141 having a spline hole 140 and a small-diameter cylindrical portion 142 that projects integrally from one end surface of the large-diameter annular portion 141. One end of the small diameter cylindrical portion 142 is brought into contact with the other end surface of the support plate 123. The push rod 102 is inserted into the rotating member 125, and the spline hole 140 of the large-diameter annular portion 141 of the rotating member 125 and the spline shaft 108 of the push rod 102 are splined. As a result, the rotating member 125 and the push rod 102 can transmit mutual rotational torque.

  The second spring clutch 124 is wound around the outer peripheral surface of the small diameter cylindrical portion 142 of the rotating member 125. Similar to the first spring clutch 100, the second spring clutch 124 includes a distal end portion 124A facing outward in the radial direction and a coil portion 124B continuously wound from the distal end portion 124A. . Then, the distal end portion 124 </ b> A of the second spring clutch 124 is fitted into one of the narrow locking grooves 133 of the retainer 110, and the coil portion 124 </ b> B is wound around the outer peripheral surface of the small diameter cylindrical portion 142 of the rotating member 125. . The second spring clutch 124 applies a rotational resistance torque to the rotational direction (the rotational direction at the time of application) when the rotating member 125 (push rod 102) moves toward the bottom 19 side of the piston 18 with respect to the retainer 110. On the other hand, it is configured to allow rotation in the rotation direction (rotation direction at release) when moving to the bottom wall 11 side of the cylinder 15.

  The rotational resistance torque when the second spring clutch 124 is applied is greater than the rotational resistance torque of the first screw fitting portion 105 between the male screw portion 103 of the push rod 102 and the female screw portion 97 of the base nut 75. Set to be larger. A ball and ramp mechanism 127 is disposed on the other end side of the rotating member 125 via a thrust bearing 126. The rotating member 125 is rotatably supported by a ball and ramp mechanism 127 via a thrust bearing 126.

  The ball-and-ramp mechanism 127 includes a fixed lamp 150, a rotation / linear motion lamp 151, and each ball 152 interposed between the fixed lamp 150 and the rotation / linear motion lamp 151. The fixed lamp 150 is disposed on the other end side of the rotating member 125 via a thrust bearing 126. The fixed lamp 150 includes a disk-shaped fixed plate 154 and a plurality of convex portions 155 that protrude from the outer peripheral surface of the fixed plate 154 at intervals along the circumferential direction. In the present embodiment, three convex portions 155 are formed. An insertion hole 156 through which the push rod 102 is inserted is formed at the center in the radial direction of the fixed plate 154. The fixed ramp 150 has its convex portions 155 fitted into the wide locking grooves 134 of the retainer 110 and fitted into the rotation restricting vertical grooves 22 provided on the inner peripheral surface of the piston 18. The piston 18 is supported so as not to rotate relative to the piston 18 and to be movable in the axial direction. On the other end surface of the fixed plate 154, a plurality of ball grooves 157 having a predetermined inclination angle along the circumferential direction and extending in an arc shape and having an arc-shaped cross section in the radial direction are formed in the present embodiment. ing.

  The rotation / linear motion ramp 151 includes an annular rotation / linear motion plate 160 and a cylindrical portion 161 that protrudes integrally from a central portion in the radial direction of the other end surface of the rotation / linear motion plate 160. On the inner peripheral surface from the rotary translation plate 160 to the cylindrical portion 161, a female screw portion 162 into which the male screw portion 104 of the push rod 102 is screwed is formed. On the surface of the rotary linear motion plate 160 facing the fixed plate 154 of the fixed lamp 150, a plurality of books having a predetermined inclination angle along the circumferential direction and extending in an arc shape and having an arc-shaped cross section in the radial direction In the embodiment, three ball grooves 163 are formed. In addition, each ball groove 157 of the fixed ramp 150 and each ball groove 163 of the rotary linear motion ramp 151 may be configured by forming a recess in the middle of the inclination along the circumferential direction or changing the inclination in the middle. good.

  As shown in FIGS. 6 and 7, the ball 152 is interposed between the ball grooves 163 of the rotation / linear motion ramp 151 (rotation / linear motion plate 160) and the ball grooves 157 of the stationary ramp 150 (fixation plate 154). Each is intervened. Then, when a rotational torque is applied to the rotation / linear motion ramp 151, each ball 152 between each ball groove 163 of the rotation / linear motion plate 160 and each ball groove 157 of the fixed plate 154 rolls. Due to the rotational difference between the plate 160 and the fixed plate 154, the relative distance in the axial direction between the rotary translation plate 160 and the fixed plate 154 varies.

  An annular pressing plate 129 is disposed on the other end surface around the cylindrical portion 161 of the rotary translation plate 160 via a thrust bearing 128. On the outer peripheral surface of the annular pressing plate 129, a plurality of convex portions 168 are provided protruding at intervals along the circumferential direction. In the present embodiment, three convex portions 168 are formed. Each of the convex portions 168 of the annular pressing plate 129 is fitted into each of the wide locking grooves 134 of the retainer 110 and is fitted into each of the rotation restricting vertical grooves 22 provided on the inner peripheral surface of the piston 18. The piston 18 is supported so as not to rotate relative to the piston 18 and to be movable in the axial direction.

  The rotation / linear motion ramp 151 of the ball and ramp mechanism 127 is supported by an annular pressing plate 129 through a thrust bearing 128 so as to be rotatable. The other end surface of the annular pressing plate 129 comes into contact with the bottom portion 19 of the piston 18 to press the piston 18. On the other end surface of the annular pressing plate 129, an accommodation recess 171 for accommodating each claw portion 136 of the retainer 110 that is folded inward is formed on the outer peripheral portion between the projections 168.

  Further, as shown in FIG. 1, the motor 200 is electrically connected to an ECU 175 composed of an electronic control unit that drives and controls the motor 200. The ECU 175 is connected to a parking switch 176 that is operated to instruct the operation / release of the parking brake. Further, the ECU 175 can be operated regardless of the operation of the parking switch 176 based on a signal from the vehicle side (not shown).

Next, the operation of the disc brake 1 according to this embodiment will be described.
First, the action at the time of braking of the disc brake 1 as a normal hydraulic brake by the operation of a brake pedal (not shown) will be described.
When the driver depresses the brake pedal, the hydraulic pressure corresponding to the depressing force of the brake pedal is supplied from the master cylinder to the hydraulic chamber 21 in the caliper 4 via a hydraulic circuit (both not shown). Thereby, the piston 18 moves forward (moves leftward in FIG. 1) from the original position during non-braking while elastically deforming the piston seal 16, and presses the inner brake pad 2 against the disc rotor D. The caliper body 6 moves to the right in FIG. 1 with respect to the bracket 5 by the reaction force of the pressing force of the piston 18, and presses the outer brake pad 3 attached to the claw portion 8 against the disc rotor D. As a result, the disc rotor D is sandwiched between the pair of inner and outer brake pads 2 and 3 to generate a frictional force, and hence a braking force for the vehicle.

  And when a driver | operator releases a brake pedal, supply of the hydraulic pressure from a master cylinder stops, and the hydraulic pressure in the hydraulic pressure chamber 21 falls. As a result, the piston 18 is retracted to the original position by the restoring force of the elastic deformation of the piston seal 16 and the braking force is released. Incidentally, when the movement amount of the piston 18 increases with the wear of the inner and outer brake pads 2, 3 and exceeds the limit of elastic deformation of the piston seal 16, slip occurs between the piston 18 and the piston seal 16. By this slip, the original position of the piston 18 with respect to the caliper body 6 is moved, and the pad clearance is adjusted to be constant.

Next, an operation as a parking brake, which is an example of an operation for maintaining the stopped state of the vehicle, will be described.
First, when the parking switch is operated from the parking brake released state and the parking brake is operated (applied), the ECU 175 drives the motor 200 and the planetary gear reduction mechanism 45 via the spur multi-stage reduction mechanism 44. The sun gear 57 is rotated. Due to the rotation of the sun gear 57, the carrier 62 is rotated through each planetary gear 60. Then, the rotational torque from the carrier 62 is transmitted to the base nut 75. When each planetary gear 60 rotates with the rotation of the sun gear 57 when the planetary gear speed reduction mechanism 45 is operated, the rotational torque from each planetary gear 60 is transmitted to the internal gear 61. At this time, the rotation of the internal gear 61 is restricted by the contact surfaces 74A and 31F of the projections 74 of the internal gear 61 and the engagement grooves 31D of the first housing 31 contacting each other. In addition, the rotational torque of each planetary gear 60 is transmitted to the carrier 62. As described above, when the contact surfaces 74A and 31F of the projections 74 of the internal gear 61 and the engagement grooves 31D of the first housing portion 31 come into contact with each other, the areas of the contact surfaces 74A and 31F are reduced. Since it is larger than the conventional one, the surface pressure of each contact surface 74A, 31F can be reduced, and the collision sound (operation sound) at the time of contact can be reduced.

  Next, the rotational resistance torque in the apply direction of the rotating member 125 (push rod 102) to the retainer 110 (piston 18) by the second spring clutch 124 causes the first screw fit between the push rod 102 and the base nut 75. It is set to be larger than the rotational resistance torque by the joint portion 105. Accordingly, the first spring clutch 100 is allowed to rotate the push rod 102 in the apply direction with respect to the base nut 75. Therefore, the rotation of the base nut 75 in the apply direction causes the first screw fitting portion 105 to rotate relatively, that is, only the base nut 75 rotates in the apply direction, while the push rod 102 extends along the axial direction. The piston 18 moves forward toward the bottom 19 side.

  As a result, the one end side washer 120 in the retainer 110 including the retainer 110 together with the push rod 102, the coil spring 121, the other end side washer 122, the support plate 123, the second spring clutch 124, the rotating member 125, the thrust bearing 126, the ball and The constituent members of the ramp mechanism 127, the thrust bearing 128, and the annular pressing plate 129 are integrally moved toward the bottom 19 side of the piston 18 along the axial direction. By advancement of these components, the annular pressing plate 129 comes into contact with the bottom portion 19 of the piston 18, and the piston 18 advances and one end surface of the bottom portion 19 of the piston 18 comes into contact with the inner brake pad 2.

  When the rotation of the motor 200 in the apply direction is continued, the piston 18 starts to press the disc rotor D via the inner and outer brake pads 2 and 3 by the movement of the push rod 102. When this pressing force starts to be generated, this time, the rotational resistance torque in the first screw fitting portion 105 between the push rod 102 and the base nut 75 increases due to the axial force that is the reaction force against the pressing force. Thus, the rotational resistance torque of the second spring clutch 124 becomes larger. As a result, the push rod 102 starts to rotate in the apply direction together with the rotating member 125 as the base nut 75 rotates. Then, due to the reaction force from the pressing force of the disk rotor D, the rotational resistance torque in the second screw fitting portion 106 between the push rod 102 and the ball and ramp mechanism 127 also increases due to the reaction force of the pressing force of the disk rotor D. For this reason, the rotational torque in the apply direction of the push rod 102 is transmitted to the rotary linear motion lamp 151 of the ball and ramp mechanism 127 via the second screw fitting portion 106.

  At this time, the rotational torque in the apply direction of the push rod 102 causes a relative rotation difference (the rotation linear motion lamp 151 rotates slightly behind the push rod 102) at the second screw fitting portion 106. Then, it is transmitted to the rotation / linear motion lamp 151 of the ball and ramp mechanism 127. Then, each of the balls 152 rolls while the rotary linear motion lamp 151 of the ball and ramp mechanism 127 rotates in the apply direction, and the rotary linear motion ramp 151 and the fixed ramp 150 resist the urging force of the coil spring 121. Then, the annular pressing plate 129 further presses the bottom portion 19 of the piston 18 by being separated. Thereby, the pressing force of the disc rotor D by the inner and outer brake pads 2 and 3 increases.

  In the disc brake 1 according to the present embodiment, first, the first screw fitting portion 105 between the push rod 102 and the base nut 75 relatively rotates, the push rod 102 moves forward, and the piston 18 is moved. Advancing to obtain a pressing force to the disk rotor D. For this reason, the operation of the first screw fitting portion 105 can adjust the original position of the push rod 102 with respect to the piston 18 that changes due to the wear of the inner and outer brake pads 2 and 3 with time.

  The ECU 175 drives the motor 200 until the pressing force from the pair of inner and outer brake pads 2 and 3 to the disc rotor D reaches a predetermined value, for example, until the current value of the motor 200 reaches a predetermined value. Thereafter, when the ECU 175 detects that the pressing force to the disk rotor D has reached a predetermined value by the fact that the current value of the motor 200 has reached a predetermined value, the ECU 175 stops energization of the motor 200. Then, the linear motion accompanying the rotation of the rotary linear motion lamp 151 of the ball and ramp mechanism 127 is stopped.

  Eventually, the reaction force of the pressing force from the disk rotor D acts on the rotary linear motion lamp 151, but the second screw fitting portion 106 between the push rod 102 and the ball and ramp mechanism 127 is The first screw fitting portion 105 between the push rod 102 and the base nut 75 is also constituted by a screw fitting portion that does not reversely operate. Since the first spring clutch 100 applies a rotational resistance torque in the release direction to the push rod 102 with respect to the base nut 75, the piston 18 is held in the braking position. As a result, the braking force is maintained and the operation of the parking brake is completed.

  Next, when the parking brake is released (released), the motor 200 is rotationally driven in the release direction for separating the piston 18 from the disk rotor D by the ECU 175 based on the parking release operation of the parking switch 176. Thereby, the spur multi-stage reduction mechanism 44 and the planetary gear reduction mechanism 45 are driven to rotate in the release direction for returning the piston 18, and the rotation drive in the release direction is transmitted to the base nut 75 via the carrier 62.

  At this time, the reaction force of the pressing force from the disk rotor D acts on the push rod 102. In other words, the push rod 102 has a second force between the push rod 102 and the ball and ramp mechanism 127. The rotation resistance torque of the screw fitting portion 106, the rotation resistance torque of the first screw fitting portion 105 between the push rod 102 and the base nut 75, and the base nut 75 of the push rod 102 by the first spring clutch 100. And a rotational resistance torque in the release direction with respect to. For this reason, the rotational torque in the release direction from the base nut 75 is transmitted to the push rod 102 (including the rotating member 125) and also to the rotary linear motion lamp 151 of the ball and ramp mechanism 127. As a result, the rotation linear motion lamp 151 only rotates in the release direction and returns to the initial position in the rotation direction.

  Next, the reaction force to the push rod 102 is reduced, and the rotation resistance torque of the second screw fitting portion 106 between the push rod 102 and the ball and ramp mechanism 127 becomes the base nut by the first spring clutch 100. The rotational resistance torque in the release direction of the push rod 102 with respect to 75 is added to the rotational resistance torque of the first screw fitting portion 105 between the push rod 102 and the base nut 75, so that the rotational resistance becomes smaller. Since the dynamic ramp 151 can no longer rotate in the release direction, only the second screw fitting portion 106 relatively rotates, and the rotary linear motion ramp 151 of the ball and ramp mechanism 127 along with the retainer 110 along the axial direction. Then, it moves to the bottom wall 11 side (release direction) of the cylinder 15 and returns to the initial position in the axial direction.

  Further, when the motor 200 is driven to rotate in the release direction and the rotation of the base nut 75 continues in the release direction, the rotation linear motion lamp 151 of the ball and ramp mechanism 127 returns to the initial position in the axial direction, and the push rod The second screw fitting portion 106 between the ball 102 and the ball and ramp mechanism 127 returns to the initial screwing position, and the rotation of the push rod 102 in the release direction is stopped.

  When the rotation of the base nut 75 is further continued, the push rod 102 moves in the axial direction against the rotational resistance torque in the release direction of the push rod 102 with respect to the base nut 75 by the first spring clutch 100. Along the bottom wall 11 side (release direction) of the cylinder 15. As a result, the one end side washer 120 in the retainer 110 including the retainer 110 together with the push rod 102, the coil spring 121, the other end side washer 122, the support plate 123, the second spring clutch 124, the rotating member 125, the thrust bearing 126, the ball and The constituent members of the ramp mechanism 127, the thrust bearing 128, and the annular pressing plate 129 are integrally retreated toward the bottom wall 11 side (release direction) of the cylinder 15 along the axial direction. Then, the piston 18 is retracted to the original position by the restoring force of the elastic deformation of the piston seal 16 and the braking force is completely released.

As described above, in the disc brake 1 according to the present embodiment, the contact surfaces 74A and 31F of the protrusions 74 of the internal gear 61 and the engagement grooves 31D of the first housing part 31 are connected to the internal gear. It is made to incline with respect to the axial direction of 61, and it is formed so that the area of each contact surface 74A, 31F may become larger than before.
When the planetary gear speed reduction mechanism 45 is operated by driving the motor 200, the contact surfaces 74 </ b> A and 31 </ b> F of the protrusions 74 of the internal gear 61 and the engagement grooves 31 </ b> D of the first housing portion 31 come into contact with each other. It is possible to reduce the surface pressure of each contact surface 74A, 31F when the contact is made, and to mitigate the collision sound (operation sound) at the time of contact. Further, since the contact surfaces 74A and 31F are inclined with respect to the axial direction, the contact surfaces 74A and 31F of the projections 74 of the internal gear 61 and the engagement grooves 31D of the first housing portion 31 are mutually connected. , The reaction force applied to the contact surface 74A of each projection 74 of the internal gear 61 due to the rotational torque of the internal gear 61 is dispersed in the axial direction. Then, since this axially directed torque is received by the annular stopper portion 56A provided on the large gear 56 of the second reduction gear 49, which restricts the axial movement of the internal gear 61, each contact surface 74A. , 31F can be further reduced.

  Furthermore, the pair of opposing contact surfaces 31F, 31F of each engagement groove 31 of the first housing portion 31 are inclined with respect to the axial direction so as to be separated from each other toward the cover 36 side. The thickness of the engagement groove 31D near the bottom of the pair of contact surfaces 31F and 31F can be increased, and the safety factor against the breaking strength when contacting the projections 74 of the internal gear 61 can be improved. it can.

  In the above-described embodiment, the internal gear 61 is supported by the first housing portion 31 of the housing 30 so as not to be relatively rotatable. However, as another embodiment, as shown in FIG. The ring-shaped support portion 207 of the holder 205 may be supported so as not to be relatively rotatable. In the case of this embodiment, a plurality of engaging grooves 31D are formed on the lower end surface of the ring-shaped support portion 207 at intervals in the circumferential direction. In the case of this embodiment, the pair of contact surfaces 74A, 74A of each projection 74 of the internal gear 61 are in the axial direction of the internal gear 61 so as to be close to each other toward the cover 36 side. Each is inclined. Similarly, the pair of contact surfaces 31F and 31F of each engagement groove 31D of the holder 205 (ring-shaped support portion 207) are also close to each other toward the cover 36 with respect to the axial direction of the ring-shaped support portion 207. Each tilted. The holder 205 corresponds to a support member.

  As yet another embodiment, as shown in FIG. 9, the internal gear 61 may be supported by the cover 36 so as not to be relatively rotatable. In the case of this embodiment, a ring-shaped portion 38 arranged so as to surround the internal gear 61 at the time of assembly is suspended from the cover 36, and a circumferential interval is provided at the lower end surface of the ring-shaped portion 38. A plurality of engaging grooves 31D are formed. In the case of this embodiment, the pair of contact surfaces 74A, 74A of each projection 74 of the internal gear 61 are in the axial direction of the internal gear 61 so as to be close to each other toward the cover 36 side. Each is inclined. Similarly, the pair of contact surfaces 31F and 31F of each engagement groove 31D of the ring-shaped portion 38 are also inclined with respect to the axial direction of the ring-shaped portion 38 so as to be close to each other toward the cover 36 side. . The cover 36 corresponds to a support member.

  In the disc brake 1 according to the present embodiment shown in FIGS. 1 to 9, the protrusions 74 of the internal gear 61 and the engagement grooves 31 </ b> D of the first housing portion 31 (or the holder 205 and the cover 36). The contact surfaces 74A and 31F of each other are inclined with respect to the axial direction of the internal gear 61. As shown in FIGS. The area of each contact surface 74A, 31F can be formed larger than the conventional one by inclining with respect to the radial direction. In the case of this embodiment, from the viewpoint of the strength of the projecting portion 74, the pair of contact surfaces 74A, 74A of the projecting portion 74 should be inclined so as to approach each other as going outward in the radial direction.

  1 disc brake, 2 inner brake pad, 3 outer brake pad, 4 caliper, 6 caliper body, 7 cylinder part, 15 cylinder, 18 piston, 43 piston propulsion mechanism, 30 housing (support member), 31 first housing, 31D Joint groove, 31F contact surface, 36 cover (support member), 38 ring-shaped part, 45 planetary gear speed reduction mechanism, 61 internal gear, 74 protrusion, 74A contact surface, 200 motor, 205 holder (support member), 207 ring Support, D disk rotor

Claims (1)

A piston that presses one of the pair of pads arranged on both sides in the axial direction of the rotor across the rotor against the rotor;
A caliper body having a cylinder in which the piston is movably housed and a piston propulsion mechanism for propelling the piston is housed;
A motor provided in the caliper body;
A speed reduction mechanism for increasing the rotational force from the motor and transmitting it to the piston propulsion mechanism;
A support member attached to the caliper main body and supporting the speed reduction mechanism,
A planetary gear reduction mechanism is provided as the reduction mechanism,
The planetary gear speed reduction mechanism has an internal gear supported by the support member so as not to rotate relative to the support member.
On the outer peripheral surface of the internal gear, a plurality of projecting portions projecting radially outward at intervals in the circumferential direction,
The support member has a plurality of engagement grooves with which the protrusions engage,
The contact surfaces of the protrusion and the engagement groove along the circumferential direction are inclined with respect to the axial direction of the internal gear or the radial direction of the protrusion. brake.

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