JP2021049879A - Disc brake - Google Patents

Abstract

To provide a disc brake that decreases a variation width of release operation time of an electric parking brake, and improves feeling at the time of automatic releasing.SOLUTION: A disc brake 1A includes a roller cage 120 which is disposed between a shaft member 75 and a nut member 77 and arranged with a plurality of roller storage holes 121 storing a planetary roller 76 in a circumferential direction, and a coil spring 128 that is wound around an outer peripheral surface of a shaft member 75, abuts on an axial end portion of a roller cage 129 at one end, has a larger diameter on the other end side than that of the one end side, and is formed with a larger pitch on the other end side than that on the one end side. Therefore, a variation width of release operation time of an electric parking brake is decreased to improve feeling at the time of automatic releasing.SELECTED DRAWING: Figure 2

Description

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

A disc brake equipped with an electric parking brake is known as a braking device for a vehicle. For example, the disc brake described in Patent Document 1 is provided with a piston propulsion mechanism that converts a rotational motion of a motor gear unit into a linear motion to propel a piston and hold the propelled piston at a braking position. This piston propulsion mechanism includes a spindle rod to which rotation from an electric motor is transmitted, an adjuster nut that is screw-engaged with the spindle rod, a ring shaft that is non-rotatably supported on the bottom surface of the cylinder, and an adjuster nut. It is equipped with a plurality of planetary rods arranged between the ring shaft and the ring shaft.

International Publication No. 2018/003393 Pamphlet

However, in the piston propulsion mechanism described in Patent Document 1 described above, there may be a large variation in the release operation time when the parking brake is released. As a result, as a vehicle system, there is a risk that the feeling at the time of auto release (accelerator release) will deteriorate. One of the causes is the variation in the operation start time of the piston propulsion mechanism with respect to the input torque from the motor gear unit at the start of release. That is, the torque required to operate the first screw fitting portion between the male screw portion of the spindle and the female screw portion of the adjuster nut is applied to the engaging portion between each planetary roller and the adjuster nut and nut member. When it is generated, the axial reaction force generated at the same time tightens the first screw fitting portion, and the operation start torque of the first screw fitting portion becomes large. As a result, the magnitude of the tightening force due to the axial reaction force in the first screw fitting portion is necessary because it amplifies the variation in the frictional force in the first screw fitting portion. The variation in operating torque is amplified until it exceeds the variation in frictional force at the first screw fitting portion. Therefore, the operation start time of the piston propulsion mechanism is not stable, and the release operation time varies with each operation.

An object of the present invention is to provide a disc brake that reduces the variation in the release operating time of the electric parking brake and improves the feeling at the time of auto release.

The first disc brake according to the present invention includes a pair of pads arranged on both sides of the rotor in the axial direction, a piston that presses one of the pair of pads against the rotor, and the piston. A caliper body having a cylinder that is slidably fitted, a motor provided in the caliper body, and a rotary linear motion provided in the caliper body that converts the rotational motion of the motor into a linear motion to propel the piston. A conversion mechanism is provided, and the rotary linear motion conversion mechanism includes a tubular member, a shaft member arranged radially inside the tubular member, and a circumference thereof between the shaft member and the tubular member. A plurality of rolling elements arranged at intervals in the direction and engaged with the shaft member and the tubular member, and accommodation holes arranged between the shaft member and the tubular member and accommodating the rolling element are provided. A plurality of roller cages provided along the circumferential direction are wound around the outer peripheral surface of the shaft member, one end of which abuts on the axial end of the roller cage, and the other end side has a larger diameter than the one end side. Another feature is that a coil-shaped member having a larger pitch on the one end side than the one end side is provided.

The second disc brake according to the present invention includes a pair of pads arranged on both sides of the rotor in the axial direction, a piston that presses one of the pair of pads against the rotor, and the like. A caliper body having a cylinder into which a piston is slidably fitted, a motor provided in the caliper body, and a rotation provided in the caliper body that converts the rotational motion of the motor into a linear motion to propel the piston. A linear motion conversion mechanism is provided, and the rotary linear motion conversion mechanism is provided between a tubular member, a shaft member arranged radially inside the tubular member, and between the shaft member and the tubular member. A plurality of rolling elements are arranged at intervals in the circumferential direction and engaged with the shaft member and the tubular member, and are arranged between the shaft member and the tubular member to accommodate the rolling element. It is characterized by including a roller cage in which a plurality of holes are provided along the circumferential direction, and a clutch member that switches between relative rotation or integral rotation of the shaft member and the roller cage according to the rotation direction of the shaft member. To do.

According to the disc brake of the present invention, it is possible to reduce the variation width of the release operation time of the electric parking brake and improve the feeling at the time of auto release.

Sectional drawing of the disc brake which concerns on 1st Embodiment. Enlarged view of the main part of FIG. An exploded perspective view of the piston propulsion mechanism in the disc brake of FIG. 1. (A) is a plan view from one end side of the assembled state of the shaft member, the coil spring and the roller cage in the disc brake of FIG. 1, and (b) is a cross section taken along the line AA of (a). (A) is a side view in which one end of the coil spring can be visually recognized in the assembled state of the shaft member, the coil spring and the roller cage in the disc brake of FIG. 1, and (b) is a side view in which the other end of the coil spring can be visually recognized. .. Sectional drawing of the disc brake which concerns on 2nd Embodiment. Enlarged view of the main part of FIG. An exploded perspective view of the piston propulsion mechanism in the disc brake of FIG. (A) is a plan view from the other end side of the state in which the coil spring and the roller cage are assembled to the spindle in the disc brake of FIG. 6, and (b) is a cross section taken along the line BB of (a). (A) is a side view in which the other end of the coil spring can be visually recognized when the coil spring and the roller cage are assembled to the spindle in the disc brake of FIG. 6, and (b) is a side view in which one end of the coil spring can be visually recognized. ..

Hereinafter, the disc brakes 1A and 1B according to the first and second embodiments will be described in detail with reference to FIGS. 1 to 10, respectively. In the following description, for convenience of explanation, the right side in FIGS. 1, 2, 6 and 7 is defined as one end side of the disc brakes 1A and 1B according to the first and second embodiments, and FIGS. 1, 2, and 6 The left side in FIG. 7 is the other end side of the disc brakes 1A and 1B according to the first and second embodiments. Further, the left-right direction in FIGS. 1, 2, 6 and 7 is the axial direction in the disc brakes 1A and 1B according to the first and second embodiments.

First, the disc brake 1A according to the first embodiment will be described in detail with reference to FIGS. 1 to 5.
As shown in FIG. 1, the disc brake 1A according to the first embodiment is arranged on both sides in the axial direction of the disc rotor D (rotor) attached to a rotating portion (not shown) of the vehicle. A pair of inner and outer brake pads 2 and 3 and a floating caliper 4 are provided. The pair of inner and outer brake pads 2, 3 and the floating caliper 4 are supported so as to be movable in the axial direction by a carrier 5 fixed to a non-rotating portion (not shown) such as a knuckle of a vehicle.

The caliper body 6, which is the main body of the caliper 4, extends from the cylinder portion 7 formed on the base end side (one end side) to the other end side so as to straddle the disc rotor D, and extends to the other end side (other). It has a claw portion 8 formed on the end side). The cylinder portion 7 is formed with a cylinder 10 in which the piston 18 is slidably fitted along the axial direction. The cylinder 10 has a large-diameter opening 10A with the other end open and a bottomed small-diameter opening 10B closed by a bottom 13 having a shaft hole 12 on one end. On the bottom surface of the cylinder 10, an engaging recess (not shown) with which the stopper protrusion 160 provided on the nut member 77, which will be described later, is engaged is formed. An annular groove 14 is formed in the large-diameter opening 10A of the cylinder 10 and on the inner wall surface on the other end side. A piston seal 16 is provided in the annular groove 14.

The piston 18 is formed in a cup shape including a cylindrical portion 20 and a bottom portion 19. The piston 18 is arranged so that the bottom portion 19 faces the inner brake pad 2. The piston 18 is slidably fitted in the large-diameter opening 10A of the cylinder 10 along the axial direction. The outer peripheral surface of the cylindrical portion 20 of the piston 18 is brought into contact with the piston seal 16. A hydraulic chamber 21 partitioned by the piston seal 16 is formed between the piston 18 and the bottom 13 of the cylinder 10. The hydraulic pressure chamber 21 is supplied with hydraulic pressure from a hydraulic pressure source (not shown) such as a master cylinder and a hydraulic pressure control unit via a port (not shown) provided in the cylinder portion 7. A recess 25 is formed in the outer peripheral edge of the bottom 19 of the piston 18. A convex portion 26 formed on the back surface of the inner brake pad 2 is engaged with the concave portion 25. As a result, the piston 18 cannot rotate relative to the cylinder 10 and the caliper main body 6. A dust boot 27 is provided between the bottom 19 of the piston 18 and the large diameter opening 10A of the cylinder 10. A bottom portion 19 of the piston 18, on the inner surface on one end side thereof, a circular recess 30 located at the center in the radial direction, and an annular inclined portion 31 whose diameter is continuously increased toward one end side of the circular recess 30. , Is formed.

The caliper main body 6 is provided with a motor gear unit 36 incorporating an electric motor 35 and a reduction mechanism, and a piston propulsion mechanism 37 as a rotation linear motion conversion mechanism. The piston propulsion mechanism 37 converts the rotational motion (output) of the motor gear unit 36 into a linear motion to propel the piston 18 (move it to the other end side) and hold the piston 18 in the braking position. .. An electronic control unit 38 that controls the electric motor 35 is connected to the motor gear unit 36. A parking switch 39, which is operated when the parking brake is turned on / off, is connected to the electronic control unit 38. The electronic control unit 38 can operate the parking brake based on a signal from the vehicle side without operating the parking switch 39. The reduction mechanism of the motor gear unit 36 includes, for example, a spur tooth multi-stage reduction mechanism, a planetary gear reduction mechanism, and the like.

With reference to FIGS. 2 and 3, the piston propulsion mechanism 37 includes a spindle 48, a sliding screw engaging portion 45, and a roller screw mechanism 46. The spindle 48 includes a shaft portion 49 formed on one end side, a male screw portion 50 formed on the other end side, and a flange portion 51 formed between the shaft portion 49 and the male screw portion 50. .. A polygonal shaft portion 53 is formed at one end of the shaft portion 49 of the spindle 48. In the present embodiment, the polygonal shaft portion 53 is formed on the hexagonal shaft portion. The polygonal shaft portion 53 is connected to a reduction mechanism of the motor gear unit 36 (for example, a carrier of a planetary reduction gear mechanism or the like) so as not to rotate relative to each other. As a result, the rotational torque from the motor gear unit 36 is transmitted to the spindle 48. The shaft portion 49 of the spindle 48 and the reduction mechanism of the motor gear unit 36 are connected by using a mechanical element capable of transmitting rotational torque, such as a spline and a key, in addition to the rotation stop by the polygonal shaft portion 53 described above. be able to. The male threaded portion 50 of the spindle 48 is arranged so that the other end face is close to the circular recess 30 provided in the bottom portion 19 of the piston 18. The flange portion 51 is annular and protrudes outward in the radial direction. A rolling concave surface 54 of the thrust ball 65 is formed on one end surface of the flange portion 51 of the spindle 48. A plurality of convex portions 55 are formed on the other end surface of the flange portion 51 of the spindle 48 at intervals along the circumferential direction.

A shaft hole 12 through which the shaft portion 49 of the spindle 48 is inserted is formed in the bottom portion 13 of the cylinder 10. The guide sleeve 56 is fitted on the inner peripheral surface of the shaft hole 12. The shaft portion 49 of the spindle 48 is rotatably supported by the caliper body 6 via the guide sleeve 56. The shaft hole 12 of the cylinder 10 and the shaft portion 49 of the spindle 48 are sealed by a seal ring 57. The seal ring 57 is arranged on the other end side of the guide sleeve 56. The base plate 60 is arranged in the cylinder 10 near the bottom portion 13. The base plate 60 is formed in the shape of an annular plate having a shaft hole 61 in the center in the radial direction. The base plate 60 is arranged on the inner peripheral side of one end of the nut member 77, which will be described later. Specifically, the base plate 60 is arranged on the inner peripheral side of one end of the large-diameter nut portion 151 of the nut member 77 so as to face one end side (rolling concave surface 54) of the flange portion 51 of the spindle 48. The shaft portion 49 of the spindle 48 is slidably inserted into the shaft hole 61 of the base plate 60. A rolling concave surface 63 of the thrust ball 65 is formed on the other end surface of the base plate 60. Then, a plurality of thrust balls 65 are rotatably arranged between the rolling concave surface 54 provided on one end surface of the flange portion 51 of the spindle 48 and the rolling concave surface 63 provided on the other end surface of the base plate 60. The plurality of thrust balls 65 are held by the retainer 66 at regular intervals in the circumferential direction.

An inclined surface 68 whose diameter is reduced toward one end is formed on the outer peripheral surface of one end of the base plate 60. A C-shaped retaining ring 70 is mounted between the inclined surface 68 of the base plate 60 and the retaining groove portion 158 of the nut member 77 described later. The retaining ring 70 regulates the base plate 60 from moving to one end side with respect to the nut member 77, in other words, urges the nut member 77 to the other end side. The retaining ring 70 is a retaining ring for a hole having a circular cross section, and is mounted in the retaining groove 158 of the nut member 77 in a compressed (diameter-reduced) state. A plurality of notches 71 (see FIG. 3) for circulating the brake fluid in the axial direction are formed on the outer peripheral surface of the base plate 60.

The sliding screw engaging portion 45 is composed of a screwed portion between the male screw portion 50 of the spindle 48 and the female screw portion 84 of the shaft member 75, which will be described later. The sliding screw engaging portion 45 is configured to be able to move the shaft member 75 in the rotational direction and the axial direction when the spindle 48 is rotated in the apply direction or the release direction. The reverse efficiency of the sliding screw engaging portion 45 is set to 0 or less, and the spindle 48 cannot be rotated by the axial thrust acting on the shaft member 75. That is, the sliding screw engaging portion 45 can convert the rotational torque of the spindle 48 into the axial thrust of the shaft member 75, but the axial thrust of the shaft member 75 can be converted into the rotational torque of the spindle 48. Cannot be converted to.

The roller screw mechanism 46 includes a shaft member 75 as a shaft member, a planetary roller 76 as a rolling element, and a nut member 77 as a tubular member. The shaft member 75 is formed in a cylindrical shape. The shaft member 75 is arranged around the spindle 48. The shaft member 75 is configured by integrally connecting a small-diameter shaft portion 79 formed on one end side and a large-diameter shaft portion 80 formed on the other end side. An annular stepped portion 81 (see FIGS. 2 and 3) is formed between the outer peripheral surface of the small diameter shaft portion 79 and the outer peripheral surface of the large diameter shaft portion 80. A plurality of convex portions 82 (see FIG. 3) are formed on one end surface of the small diameter shaft portion 79 at intervals in the circumferential direction. When the plurality of convex portions 82 provided on the shaft member 75 and the plurality of convex portions 55 provided on the other end surface of the flange portion 51 of the spindle 48 interfere with each other, the relative rotation of the two is restricted. This prevents the spindle 48 (male threaded portion 50) from sticking (biting) to the shaft member 75 (female threaded portion 84) due to excessive screwing.

An annular groove portion 83 having a predetermined pitch is formed along the axial direction on the outer peripheral surface of the shaft member 75 near one end of the small diameter shaft portion 79. Each annular groove portion 83 is engaged with each annular mountain portion 110 provided on the outer peripheral surface of each planetary roller 76. On the inner peripheral surface of the small-diameter shaft portion 79, a female screw portion 84 is formed at a portion excluding a predetermined range on one end side. The male threaded portion 50 of the spindle 48 is screwed onto the female threaded portion 84 and acts as a sliding screw engaging portion 45. The large-diameter shaft portion 80 is formed with a communication hole 86 that penetrates the peripheral wall portion along the radial direction. A plurality of the communication holes 86 are formed at intervals along the circumferential direction. In the present embodiment, the communication holes 86 are formed at two positions at a pitch of 180 ° along the circumferential direction. A rolling concave surface 88 of the thrust ball 99 is formed on the other end surface of the large diameter shaft portion 80. The shaft hole of the large diameter shaft portion 80 has a larger diameter than the female thread portion 84 of the small diameter shaft portion 79. A holder fitting hole 89 having a diameter larger than that of the female screw portion 84 is formed on the other end side of the shaft hole. A bearing holder 103, which will be described later, is fitted into the holder fitting hole 89.

The thrust plate 92 is arranged so as to face the other end surface of the shaft member 75 (large diameter shaft portion 80). The thrust plate 92 is formed in an annular shape having a shaft hole 93 into which the male screw portion 50 of the spindle 48 is inserted. The inner diameter of the shaft hole 93 of the thrust plate 92 substantially matches the inner diameter of the holder fitting hole 89 of the large diameter shaft portion 80. A plurality of notches 95 (see FIG. 3) for circulating the brake fluid in the axial direction are formed on the outer peripheral surface of the thrust plate 92. On the other end surface of the thrust plate 92, a contact surface 94 that comes into contact with the inclined portion 31 provided on the bottom portion 19 of the piston 18 is formed. A rolling concave surface 97 of the thrust ball 99 is formed on one end surface of the thrust plate 92. Then, a plurality of thrust balls 99 are rotatably arranged between the rolling concave surface 97 of the thrust plate 92 and the rolling concave surface 88 of the shaft member 75 (large diameter shaft portion 80). The plurality of thrust balls 99 are held by the retainer 100 at regular intervals in the circumferential direction.

The bearing holder 103 is inserted from the inner peripheral surface of the shaft hole 93 of the thrust plate 92 into the holder fitting hole 89 of the large diameter shaft portion 80. The bearing holder 103 is formed in a cylindrical shape. An annular locking portion 105 is formed on the outer peripheral surface of the other end of the bearing holder 103 so as to project outward in the radial direction. The bearing holder 103 is provided with two elastic pieces 106 at a pitch of 180 ° on the outer peripheral surface thereof. Each elastic piece 106 is formed by cutting the outer peripheral wall of the bearing holder 103. At the tip of each elastic piece 106, a locking claw portion 107 is projected outward in the radial direction. The locking claw portion 107 can be projected and retracted along the radial direction from the outer peripheral surface of the bearing holder 103 by elastically deforming the elastic piece 106. Then, the annular locking portion 105 of the bearing holder 103 is brought into contact with the other end surface of the thrust plate 92, and the locking claw portion 107 of each elastic piece 106 is placed in the communication hole 86 of the large diameter shaft portion 80. Engaged from the inside. The bearing holder 103 can integrally hold the thrust plate 92 together with the thrust ball 99 including the retainer 100 at the other end of the shaft member 75.

A plurality of planetary rollers 76 are arranged around each annular groove 83 on the outer circumference of the small-diameter shaft portion 79 of the shaft member 75 at intervals along the circumferential direction. In this embodiment, six planetary rollers 76 are arranged. The planetary roller 76 is formed with an annular crest 110 having a predetermined pitch along the axial direction on the outer peripheral surface thereof. Each annular ridge 110 of the planetary roller 76 is engaged with each annular groove 83 provided on the outer peripheral surface of the shaft member 75 (small diameter shaft portion 79). As a result, the relative movement of the shaft member 75 and each planetary roller 76 in the axial direction is restricted. These planetary rollers 76 are held by the roller cage 120.

As shown in FIGS. 2 to 4, the roller cage 120 holds each planetary roller 76 so that the adjacent planetary rollers 76 do not interfere with each other. The roller cage 120 is rotatably supported around the shaft member 75 with respect to the shaft member 75, and is slidably supported in the axial direction with respect to the nut member 77 described later. The roller cage 120 is formed in a cylindrical shape. The inner diameter of the roller cage 120 is slightly larger than the outer diameter of the small diameter shaft portion 79 (each annular groove portion 83) of the shaft member 75. Roller accommodating holes 121 for accommodating planetary rollers 76 are formed in the peripheral wall portion of the roller cage 120 at intervals along the circumferential direction. A plurality of roller accommodating holes 121 are formed according to the number of planetary rollers 76. In the present embodiment, six roller accommodating holes 121 are formed according to the number of planetary rollers 76.

The roller accommodating hole 121 is formed in a substantially rectangular shape in a plan view that is long in the axial direction. The roller accommodating hole 121 regulates the position of the planetary roller 76 along the circumferential direction, but the roller accommodating hole 121 and the planetary roller 76 do not come into contact with each other in the axial direction. Also with reference to FIG. 5, the annular end surface of the roller cage 120 extends spirally with a stepped portion 122. This spiral lead angle is substantially the same as the lead angle on one end side (small diameter coil portion 130) of the coil spring 128, which will be described later. With reference to FIG. 5A, a step portion 122 is formed on the other end surface of the annular shape of the roller cage 120 at the starting point extending spirally. The depth (length in the axial direction) of the step portion 122 substantially coincides with the outer diameter of the coil spring 128 described later. One end of the coil spring 128, which will be described later, engages with the step portion 122. With reference to FIG. 4A, an annular recess 123 having a diameter larger than that of the small diameter shaft portion 79 of the shaft member 75 is formed around one end opening of the roller cage 120. An annular tapered surface 124 is formed which is continuous from the annular recess 123 and whose diameter is reduced toward the other end side. When the planetary rollers 76 are accommodated in the roller accommodating holes 121, the peripheral wall portion of the roller cage 120 and the circular shape connecting the radial centers of the planetary rollers 76 are arranged so as to substantially coincide with each other. As a result, the involvement of the roller cage 120 in the engaging portion between each planetary roller 76 and the shaft member 75 and the engaging portion between each planetary roller 76 and the nut member 77 is suppressed, and each planetary roller 76 is accurately subjected to. The position can be held.

Then, with reference to FIGS. 2, 4 and 5, between the spiral other end surface of the roller cage 120 and the annular step portion 81 of the shaft member 75, the small diameter shaft portion 79 of the shaft member 75 ( The coil spring 128 is arranged around each annular groove portion 83). When the shaft member 75 rotates in the apply direction, the coil spring 128 includes the shaft member 75, the coil spring 128, and the roller until the required relative predetermined torque between the small diameter shaft 79 of the shaft member 75 and the roller cage 120 is reached. When the cage 120 is integrally rotated and exceeds the required relative predetermined torque, the relative rotation between the shaft member 75 and the roller cage 120 is promoted, while when the shaft member 75 rotates in the release direction, the shaft member 75, The coil spring 128 and the roller cage 120 are configured to rotate integrally. The coil spring 128 corresponds to a coil-shaped member or a clutch member.

The coil spring 128 is an elastic body and is composed of unequal pitches. In the present embodiment, the coil spring 128 is right-handed, but may be left-handed depending on the design requirements. The coil spring 128 is configured by integrally connecting a small-diameter coil portion 130 arranged on one end side and a large-diameter coil portion 131 arranged on the other end side and having a diameter larger than that of the small-diameter coil portion 130. The pitch of the small-diameter coil portion 130 is smaller than the pitch of the large-diameter coil portion 131. The inner diameters of the small-diameter coil portions 130 are substantially the same along the axial direction. In the free state, the inner diameter of the small-diameter coil portion 130 is smaller than the outer diameter of the small-diameter shaft portion 79 (outside the range in which each annular groove portion 83 is formed) of the shaft member 75. The small-diameter coil portion 130 has three turns in the present embodiment and is formed in close contact with each other in the axial direction, but the number of turns and the pitch may be changed according to the design requirements. The pitch of the large-diameter coil portion 131 is larger than the pitch of the small-diameter coil portion 130. The inner diameter of the large-diameter coil portion 131 is larger than the outer diameter of the large-diameter shaft portion 80 of the shaft member 75. The inner diameter (outer diameter) of the large-diameter coil portion 131 is gradually increased toward the other end side. The free length (length in the axial direction before assembly) of the large-diameter coil portion 131 is formed to be longer than the length after assembly. In the present embodiment, the large-diameter coil portion 131 has one roll, but it may be changed according to the design requirements.

Then, referring to FIGS. 4 and 5, one end of the small-diameter coil portion 130 of the coil spring 128 is engaged with the stepped portion 122 of the roller cage 120, and the small-diameter coil portion 130 and the large-diameter coil portion of the coil spring 128 are engaged. 131 is wound around the small diameter shaft portion 79 of the shaft member 75 and outside the range in which each annular groove portion 83 is formed. As a result, one end side of the small-diameter coil portion 130 of the coil spring 128 is wound so as to abut on the other end surface of the spiral shape of the roller cage 120. Further, since the small-diameter coil portion 130 of the coil spring 128 is formed to have a diameter smaller than the outer diameter of the small-diameter shaft portion 79 of the shaft member 75, the small-diameter coil portion 130 is used in the range of the small-diameter coil portion 130 after assembly. , A predetermined urging force is applied toward the small diameter shaft portion 79. In response to this urging force, the frictional resistance increases between the small-diameter shaft portion 79 of the shaft member 75 and the small-diameter coil portion 130 of the coil spring 128.

On the other hand, since the inner diameter of the large-diameter coil portion 131 of the coil spring 128 is formed to be larger than the outer diameter of the small-diameter shaft portion 79 of the shaft member 75, in the range of the large-diameter coil portion 131, from the small-diameter shaft portion 79. It is in a slightly floating state, and almost no frictional resistance is generated between the large-diameter coil portion 131 of the coil spring 128 and the small-diameter shaft portion 79 of the shaft member 75. Since the axial length of the large-diameter coil portion 131 after assembly is shorter than that before assembly, a state in which an urging force is applied along the axial direction, that is, the roller cage 120 and the shaft member 75 are large. It is assembled in a state of urging the diameter shaft portion 80 in a direction away from the axial direction.

As can be seen from FIG. 4B, a C-shaped retaining ring 135 is arranged at one end of the annular groove portion 83 provided on the outer peripheral surface of the small diameter shaft portion 79 of the shaft member 75. In the free state, the retaining ring 135 is formed to have a diameter smaller than the inner diameter of the annular groove portion 83 of the small diameter shaft portion 79, and when the retaining ring 135 is attached to the annular groove portion 83 of the small diameter shaft portion 79, it is circular. It is mounted in a state where an urging force is applied toward the annular groove portion 83. When the roller cage 120 is arranged around the small-diameter shaft portion 79 of the shaft member 75 and in the range where each annular groove portion 83 is formed, the retaining ring 135 is provided around one end opening of the roller cage 120. It comes into contact with the annular tapered surface 124.

As a result, the roller cage 120 is urged to one end side with respect to the shaft member 75 by the coil spring 128, but the retaining ring 135 regulates the movement of the roller cage 120 with respect to the shaft member 75 in the axial direction. As a result, each roller accommodating hole 121 of the roller cage 120 and each planetary roller 76 do not come into contact with each other in the axial direction. The retaining ring 135 corresponds to a locking member that regulates the relative movement of the shaft member 75 and the roller cage 120 along the axial direction. Conventionally, a coil-shaped one-way clutch or the like has generally been configured such that the winding end of the coil portion is formed in a hook shape and engaged with a mating component. However, when the load torque is large, the stress applied to the bent portion between the hook portion and the coil portion becomes large, so that, for example, the wire diameter of the one-way clutch is increased or the curvature of the bent portion is increased. There was a problem that the size was increased. However, since the coil spring 128 according to the present embodiment does not have a hook portion, miniaturization can be achieved. The operation of the coil spring 128 will be described in detail later.

As shown in FIGS. 1 to 3, the nut member 77 is formed in a stepped cylindrical shape. The nut member 77 is configured by integrally connecting a large-diameter nut portion 151 arranged on one end side and a small-diameter nut portion 152 arranged on the other end side. With reference to FIG. 3, a stopper protrusion 160 projects from one end surface of the large diameter nut portion 151 toward one end side. The stopper protrusions 160 and 160 are formed so as to face each other at a pitch of 180 °. Each stopper protrusion 160 is formed to have a substantially rectangular cross section. These stopper protrusions 160 and 160 are engaged with the engaging recesses provided in the bottom 13 of the cylinder 10 of the caliper body 6, respectively. As a result, the nut member 77 is restricted from rotating relative to the caliper main body 6 (cylinder portion 7). One end of the large diameter nut portion 151 is arranged at a position close to the bottom portion 13 of the cylinder 10. The large-diameter nut portion 151 is provided with a plurality of passages 157 that penetrate the peripheral wall portion in the radial direction and allow the brake fluid to flow at intervals along the circumferential direction. An annular retaining groove portion 158 to which the retaining ring 70 is mounted is formed on the inner peripheral surface of the large diameter nut portion 151. The other end of the small diameter nut portion 152 is located slightly on the other end side of the communication hole 86 provided in the shaft member 75 in the axial direction. A female screw portion 155 is formed on the inner peripheral surface of the small diameter nut portion 152. The female thread portion 155 is provided over substantially the entire axial direction of the small diameter nut portion 152.

The female thread portion 155 of the nut member 77 is engaged (engaged) with each annular ridge portion 110 of each planetary roller 76. The female thread portion 155 of the nut member 77 and each annular ridge 110 of the planetary roller 76 have the same pitch of the female thread 155 and the pitch (axial spacing) of each annular ridge 110, and the female thread 155 By setting the number of rows to an integral multiple of the quantity of the planetary rollers 76, they are meshed with each other. For example, when the pitch of the female screw portion 155 and each annular crest 110 is 1 mm using six planetary rollers 76, the number of threads of the female screw portion 155 is set to 6 (6 × 1 times). , The female thread portion 155 of the nut member 77 and each annular ridge portion 110 of the planetary roller 76 can be meshed with each other. The lead at this time is 6 mm.

Next, the operation of the disc brake 1A of the first embodiment will be described.
When the brake pedal (not shown) is stepped on by the driver, the hydraulic pressure corresponding to the pedaling force of the brake pedal passes through the master cylinder and the hydraulic pressure circuit (abbreviated above), and is inside the caliper body 6 (cylinder 10). It is supplied to the hydraulic chamber 21. As a result, the piston 18 moves from the original position at the time of non-braking to the other end side while elastically deforming the piston seal 16, and presses the inner brake pad 2 against the disc rotor D. Subsequently, the caliper 4 moves to one end side with respect to the carrier 5 by the reaction force of the piston 18, and presses the outer brake pad 3 in contact with the claw portion 8 against the disc rotor D. As a result, the disc rotor D is sandwiched between the pair of inner brake pads and the outer brake pads 2 and 3, and a frictional force is generated to generate a braking force of the vehicle.

On the other hand, when the brake pedal is returned by the driver, the supply of hydraulic pressure from the master cylinder to the hydraulic chamber 21 is stopped, and the hydraulic pressure in the hydraulic chamber 21 drops. 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 of the vehicle is released. If the amount of movement of the piston 18 increases and exceeds the limit of elastic deformation of the piston seal 16 due to wear of the inner and outer brake pads 2 and 3, slippage occurs between the piston 18 and the piston seal 16. , The in-situ position of the piston 18 with respect to the caliper body 6 moves due to the slip. As a result, even if the inner and outer brake pads 2 and 3 are worn, the pad clearance is adjusted to be constant.

Next, the action of the parking brake for maintaining the stopped state of the vehicle by the disc brake 1A according to the first embodiment will be described.
When the electronic control unit 38 receives an apply command (parking brake operation command) by operating the parking switch 39 or the like from the released state of the parking brake, the electric motor 35 of the motor gear unit 36 is energized to rotate the spindle 48 in the apply direction. Let me. The rotational torque transmitted to the spindle 48 is transmitted to the shaft member 75 (roller screw mechanism 46) via the sliding screw engaging portion 45 between the male screw portion 50 of the spindle 48 and the female screw portion 84 of the shaft member 75. Since the rotation resistance torque from each planetary roller 76 is applied to the shaft member 75 as a reaction force with respect to the rotation torque transmitted from the spindle 48, the shaft member 75 rotates relative to the spindle 48. At the same time, an axial thrust to the other end side (apply direction) is applied.

The rotational torque transmitted to the shaft member 75 (roller screw mechanism 46) is transferred to the planetary roller 76 via the engaging portion between each annular groove portion 83 of the shaft member 75 and each annular crest portion 110 of the planetary roller 76. Be transmitted. The rotational torque transmitted to the planetary roller 76 is transmitted to the nut member 77 via an engaging portion (meshing portion) between each annular ridge 110 of the planetary roller 76 and the female threaded portion 155 of the nut member 77. Since the nut member 77 is supported so as not to rotate relative to the cylinder portion 7 by the engagement between the stopper protrusions 160 and 160 and the accommodation recesses, each planetary roller 76 has its own rotation axis. While rotating around the center, it revolves around the axis of the nut member 77 in the apply direction (the roller cage 120 also rotates together). At this time, an axial thrust toward the other end is generated in each planetary roller 76 according to the transmitted rotational torque. The thrust generated in each planetary roller 76 is transmitted to the shaft member 75 via the engaging portion between each annular ridge 110 of the planetary roller 76 and each annular groove 83 of the shaft member 75. As a result, the shaft member 75 moves to the other end side (apply direction) while rotating.

In the sliding screw engaging portion 45 between the male screw portion 50 of the spindle 48 and the female screw portion 84 of the shaft member 75, the spindle 48 applies a rotational torque substantially equal to the rotational torque transmitted from the shaft member 75 to the planetary roller 76. Is transmitted to the shaft member 75. Therefore, as described above, the sliding screw engaging portion 45 generates an axial thrust toward the other end side according to the transmission torque. The shaft member 75 receives an axial thrust toward the other end with respect to the spindle 48 due to the axial thrust generated in the sliding screw engaging portion 45. As described above, the shaft member 75 has an axial thrust toward the other end side due to the rotational torque transmitted from the spindle 48 at the sliding screw engaging portion 45, and the nut member 77 of the roller screw mechanism 46 and each planetary roller 76. It receives the axial thrust that is the sum of the axial thrust to the other end side generated between them.

The shaft member 75 that receives the axial thrust toward the other end side (apply direction) moves toward the other end side (apply direction) while rotating along the female thread portion 155 of the nut member 77, and the thrust ball 99. The contact surface 94 of the thrust plate 92 is pressed against the inclined portion 31 of the bottom portion 19 of the piston 18. As a result, the piston 18 moves toward the other end side (apply direction) and presses the inner brake pad 2. As a result, the disc rotor D is pressed by the inner and outer brake pads 2 and 3, and a braking force of the vehicle is generated. The electronic control unit 38 stops energizing the electric motor 35 of the motor gear unit 36 when the force of the shaft member 75 pressing the piston 18, in other words, the braking force of the vehicle reaches a predetermined predetermined value. , The drive (rotation) of the spindle 48 in the apply direction is stopped. The electronic control unit 38 can calculate the force by which the shaft member 75 presses the piston 18 (thrust of the shaft member 75) based on, for example, the current value of the electric motor 35.

At the time of this application, in the stage before pressing the disc rotor D by the inner and outer brake pads 2 and 3, the reaction force from the pressing force on the disc rotor D by the inner and outer brake pads 2 and 3 is not applied, so that the shaft The relative rotational torque of the member 75 with respect to the spindle 48 is small. Therefore, in the stage before pressing the disc rotor D by the inner and outer brake pads 2 and 3, when the shaft member 75 rotates in the apply direction, one end of the coil spring 128 engages with the step portion 122 of the roller cage 120. Further, frictional resistance between the shaft member 75 and the small-diameter coil portion 130 of the coil spring 128 is also provided, and the required relative rotational torque between the shaft member 75 and the roller cage 120 has not been reached. The 75, the coil spring 128, and the roller cage 120 (including each planetary roller 76) rotate together as one. As a result, at this stage, the roller screw mechanism 46 acts as a fast-forward screw mechanism, so that the time from the start of application to the pressing of the disc rotor D by the inner and outer brake pads 2 and 3 can be shortened.

Subsequently, when the braking force generating region for pressing the disc rotor D by the inner and outer brake pads 2 and 3 is reached, the reaction force (along the axial direction) from the pressing force on the disc rotor D by the inner and outer brake pads 2 and 3 is reached. Reaction force) is applied to the roller screw mechanism 46. Then, when the required relative rotational torque between the shaft member 75 and the roller cage 120 is exceeded, the diameter of the small-diameter coil portion 130 of the coil spring 128 is expanded, and the small-diameter coil portion 130 of the coil spring 128 and the small-diameter shaft portion of the shaft member 75 are expanded. The frictional force with 79 is reduced. As a result, the shaft member 75 and the roller cage 120 easily rotate relative to each other, in other words, the roller screw mechanism 46 decelerates the planet, resulting in a high screw efficiency of 50% or more, and the other end of the shaft member 75. Propulsion to the side is increased. The magnitude of the required relative rotational torque between the shaft member 75 and the roller cage 120 can be appropriately adjusted according to the wire diameter, inner diameter, and number of turns of the coil spring 128.

As described above, when the shaft member 75 is rotated in the apply direction and the required relative rotational torque between the shaft member 75 and the roller cage 120 is exceeded, the small diameter coil portion 130 of the coil spring 128 and the small diameter shaft of the shaft member 75 Since the frictional force with the portion 79 is reduced, the roller cage 120 can be easily urged to one end side by the urging force along the axial direction of the large-diameter coil portion 131 of the coil spring 128. That is, when the shaft member 75 and the roller cage 120 rotate relative to each other, the gaps between the coil spring 128, the roller cage 120, and the retaining ring 135 along the axial direction can be eliminated. As a result, not only the dimensional variation at the time of manufacturing the parts but also the dimensional change (deterioration) due to the wear of the contact portion of each member is not affected.

Further, as described above, since the reverse efficiency of the sliding screw engaging portion 45 is 0 or less, the rotational torque of the spindle 48 can be converted into an axial thrust toward the other end side of the shaft member 75. The axial thrust on the shaft member 75 cannot be converted into the rotational torque of the spindle 48. As a result, when the electronic control unit 38 stops energizing the electric motor 35, the shaft member 75 maintains the stopped state even when the reaction force of the pressing force from the disc rotor D acts via the piston 18. be able to. As a result, the piston 18 is held in the braking position, and the operation of the parking brake is completed. When the parking brake operation is completed, the reaction force of the pressing force from the disc rotor D is applied to the caliper body 6 via the thrust plate 92, the thrust ball 99, the shaft member 75, the spindle 48, the thrust ball 65, and the base plate 60. Is transmitted to the bottom 13 of the cylinder 10 and serves as a holding force for the piston 18.

On the other hand, when the electronic control unit 38 receives a release command (parking brake release command) such as an operation of the parking switch 39, the electric motor 35 of the motor gear unit 36 is energized to rotate the spindle 48 in the release direction. The rotational torque transmitted to the spindle 48 is transmitted to the shaft member 75 via the sliding screw engaging portion 45 between the male screw portion 50 of the spindle 48 and the female screw portion 84 of the shaft member 75, and the shaft member 75 Inner and outer brake pads 2 that rotate integrally in the release direction to the roller screw mechanism 46 (the engaging portion between the shaft member 75 and each planetary roller 76 and the engaging portion between each planetary roller 76 and the nut member 77). The reaction force from the pressing force on the disc rotor D by 3 is almost eliminated. That is, the starting torque of the sliding screw engaging portion 45 between the male screw portion 50 of the spindle 48 and the female screw portion 84 of the shaft member 75 is larger than the starting torque of the roller screw mechanism 46 that functions as a fast-forward screw mechanism. Is set to. Therefore, at the time of release, the roller screw mechanism 46 operates before the sliding screw engaging portion 45, so that when the spindle 48 is rotated in the release direction, the shaft member 75 is integrally rotated with the spindle 48. Then, each annular groove portion 83 of the shaft member 75, each annular ridge portion 110 of the planetary roller 76, and the female thread portion 155 of the nut member 77 engage in the release direction. Further, when the shaft member 75 rotates, the roller screw mechanism 46 tries to decelerate the planet, and each planetary roller 76 comes into contact with the roller accommodating hole 121 in the circumferential direction.

At this time, the roller cage 120 tries to rotate (relatively rotate) with a delay with respect to the shaft member 75, and tends to move to one end side along the lead angle of the coil spring 128. However, since the roller cage 120 is restricted from moving to one end by the retaining ring 135, the roller cage 120 cannot rotate relative to each other as a result. As described above, when the shaft member 75 rotates in the release direction, the roller cage 120 cannot move in the axial direction. Therefore, the shaft member 75, the coil spring 128, and the roller cage 120 (including each planetary roller 76) are released together. Rotate in the direction. Subsequently, the rotational torque transmitted to the shaft member 75 is transmitted to the planetary roller 76 via the coil spring 128 and the roller cage 120.

The rotational torque transmitted to the planetary roller 76 is transmitted to the nut member 77 via the engaging portion (meshing portion) between each annular ridge 110 of each planetary roller 76 and each female thread 155 of the nut member 77. To. Since the nut member 77 is supported so as not to rotate relative to the cylinder portion 7 by the engagement between the stopper protrusions 160 and 160 and the accommodating recesses, each planetary roller 76 has its own annular crest. The portion 110 and the female screw portion 155 revolve around the axis of the nut member 77 in the release direction while sliding (the roller cage 120 also rotates). At this time, an axial thrust in the release direction is generated in each planetary roller 76 according to the transmitted rotational torque. The axial thrust generated in each planetary roller 76 is transmitted to the shaft member 75 via the engaging portion between each annular mountain portion 110 of each planetary roller 76 and each annular groove portion 83 of the shaft member 75.

At the time of this release, in the roller screw mechanism 46, each planetary roller 76 rotates integrally with the shaft member 75 together with the roller cage 120 without decelerating the planet, and acts as a low-efficiency fast-forward screw mechanism to act as a shaft member. 75 moves in the release direction with respect to the nut member 77. At that time, since the roller screw mechanism 46 acts as a low-efficiency screw mechanism, the axial force generated with respect to the applied rotational torque becomes small. As a result, the force for tightening the sliding screw engaging portion 45 generated by the operation of the roller screw mechanism 46 can be suppressed to a small size. In this way, at the time of release, the efficiency of the roller screw mechanism 46 is lowered, and the rotational torque input from the motor gear unit 36 to the spindle 48 is applied to the sliding screw engaging portion 45 as the roller screw mechanism 46 operates. The generated axial force can be suppressed.

After that, the shaft member 75 moves in the release direction from the braking force generation region that presses the disc rotor D by the inner and outer brake pads 2 and 3, and slides with respect to the rotational torque input from the motor gear unit 36 to the spindle 48. When the operating torque of the screw engaging portion 45 is reached, the spindle 48 and the shaft member 75 (both the coil spring 120 and the roller cage 120 also rotate) rotate relative to each other, so that the shaft member 75 moves in the release direction with respect to the spindle 48. To do. At the time of release, the roller screw mechanism 46 operates as a fast-forward screw mechanism regardless of the presence or absence of a reaction force from the pressing force on the disc rotor D by the inner and outer brake pads 2 and 3, so that the release operation time is shortened. can do.

Then, by moving the shaft member 75 in the release direction, the pressing force of the disc rotor D by the inner and outer brake pads 2 and 3 is released. When the electronic control unit 38 returns to the initial state in which a predetermined distance (clearance) is secured between the inclined portion 31 of the bottom 19 of the piston 18 and the contact surface 94 of the thrust plate 92, the motor gear unit 36 The energization of the electric motor 35 is stopped. At the time of release operation, the shaft member 75 moves to one end side while rotating relative to the spindle 48, but the convex portion 82 formed on one end surface of the shaft member 75 is the other end surface of the flange portion 51 of the spindle 48. By engaging with the convex portion 55, the relative rotation of the shaft member 75 with respect to the spindle 48 is regulated. As a result, excessive screwing of the male threaded portion 50 of the spindle 48 into the female threaded portion 84 of the shaft member 75 is suppressed.

In the disc brake 1A according to the first embodiment described above, in particular, the shaft member 75 is wound around the outer peripheral surface of the small diameter shaft portion 79 (outside the range in which each annular groove portion 83 is formed), and one end thereof is a roller cage. The coil spring 128 is provided so as to abut on the step portion 122 on the other end surface of the 120, the other end side having a larger diameter than the one end side, and the other end side having a larger pitch than the one end side.

As a result, when the shaft member 75 rotates in the stage before pressing the disc rotor D by the inner and outer brake pads 2 and 3 at the time of application, the coil spring 128 and the roller cage 120 rotate together with the shaft member 75. To do. As a result, at this stage, the roller screw mechanism 46 acts as a fast-forward screw mechanism, so that the time from the start of application to the pressing of the disc rotor D by the inner and outer brake pads 2 and 3 can be shortened. After that, the inner and outer brake pads 2 and 3 reach the braking force generating region for pressing the disc rotor D, and the reaction force (in the axial direction) from the pressing force on the disc rotor D by the inner and outer brake pads 2 and 3 is reached. When a reaction force along the line is applied to the roller screw mechanism 46, the shaft member 75 and the roller cage 120 easily rotate relative to each other when the required relative rotational torque between the shaft member 75 and the roller cage 120 is exceeded. At the beginning, in other words, the roller screw mechanism 46 decelerates the planet, the screw efficiency becomes as high as 50% or more, and the propulsive force toward the other end side of the shaft member 75 is increased.

On the other hand, at the time of release, in the roller screw mechanism 46, each planetary roller 76 rotates integrally with the shaft member 75 together with the roller cage 120 without decelerating the planet, and acts as a low-efficiency fast-forward screw mechanism to act as a shaft. The member 75 can be moved in the release direction with respect to the nut member 77. Further, since the roller screw mechanism 46 acts as a low-efficiency screw mechanism, the axial force generated with respect to the applied rotational torque can be reduced, and is generated by the operation of the roller screw mechanism 46. The force for tightening the sliding screw engaging portion 45 can be suppressed to a small value. In this way, at the time of release, the efficiency of the roller screw mechanism 46 is lowered, and the rotational torque input from the motor gear unit 36 to the spindle 48 is applied to the sliding screw engaging portion 45 as the roller screw mechanism 46 operates. The generated axial force can be suppressed. As a result, the variation range of the release operation time can be reduced, and the feeling at the time of auto release can be improved.

Further, in the disc brake 1A according to the first embodiment, it is necessary to consider slip at no load in the engaging portion between each annular groove portion 83 of the shaft member 75 and each annular crest portion 110 of each planetary roller 76. There is no need to provide a pressurization mechanism. Therefore, the tolerance of the axial dimensions of the planetary roller 76 can be increased, and the axial end face of the planetary roller 76 does not need to be finished flat, so that the manufacturing cost of the planetary roller 76 can be reduced. it can.

Next, the disc brake 1B according to the second embodiment will be described in detail with reference to FIGS. 6 to 10. When the disc brake 1B according to the second embodiment is described, only the differences from the disc brake 1A according to the first embodiment will be specifically described.
As shown in FIGS. 6 to 8, the piston propulsion mechanism 37 adopted in the disc brake 1B according to the second embodiment is composed of a roller screw mechanism 46. The roller screw mechanism 46 includes a spindle 200 as a shaft member, a planetary roller 76 as a rolling element, and a nut member 210 as a tubular member. The spindle 200 includes a small-diameter shaft portion 202 located on one end side, a large-diameter shaft portion 203 continuously and integrally connected to the other end side from the small-diameter shaft portion 202, and the other end from the large-diameter shaft portion 203. It includes an intermediate shaft portion 204 that is continuously and integrally connected to the side, and an engaging shaft portion 205 that is continuously and integrally connected to the other end side from the intermediate diameter shaft portion 204.

At one end of the small-diameter shaft portion 202 of the spindle 200, a polygonal shaft portion 53 (see FIG. 8) is formed which is connected to a reduction mechanism of the motor gear unit 36 (for example, a carrier of a planetary reduction gear mechanism or the like) so as not to rotate relative to each other. Will be done. As a result, the rotational torque from the motor gear unit 36 is transmitted to the spindle 200. An annular step portion 207 is formed between the outer peripheral surface of the large diameter shaft portion 203 of the spindle 200 and the outer peripheral surface of the intermediate diameter shaft portion 204. The outer diameter of the engaging shaft portion 205 is smaller than the outer diameter of the intermediate shaft portion 204. An annular groove portion 209 having a predetermined pitch is formed on the outer peripheral surface of the engaging shaft portion 205 along the axial direction. Each of the annular groove portions 209 is engaged with each of the annular mountain portions 110 provided on the outer peripheral surface of the planetary roller 76.

A thrust bearing 215 is arranged between the large-diameter shaft portion 203 of the spindle 200 and the bottom portion 13 in the cylinder 10. The thrust bearing 215 has shaft holes 216 and 216 in the center in the radial direction, respectively, on a pair of thrust plates 217 and 217 arranged along the axial direction and on facing surfaces of the pair of thrust plates 217 and 217, respectively. It is composed of a plurality of thrust balls 219 that are rotatably arranged between the rolling concave surfaces 218 and 218 provided. The plurality of thrust balls 219 are held by the retainer 220 at regular intervals in the circumferential direction. The small diameter shaft portion 202 of the spindle 200 is inserted through the shaft holes 216 and 216 of the thrust bearing 215. As a result, the spindle 200 is rotatably supported by the bottom portion 13 in the cylinder 10 via the thrust bearing 215. A plurality of planetary rollers 76 are arranged on the outer periphery of the engaging shaft portion 205 of the spindle 200 at intervals along the circumferential direction. The planetary roller 76 is formed with an annular crest 110 having a predetermined pitch along the axial direction on the outer peripheral surface thereof. Each annular ridge 110 of the planetary roller 76 is engaged with each annular groove 209 provided on the outer peripheral surface of the spindle 200 (engagement shaft portion 205). As a result, the relative movement of the spindle 200 and each planetary roller 76 in the axial direction is restricted. These planetary rollers 76 are held by the roller cage 120.

With reference to FIGS. 9 and 10, the roller cage 120 is rotatably supported around the engagement shaft portion 205 of the spindle 200 with respect to the spindle 200 and axially movably with a nut member 210 described below. Will be done. The inner diameter of the roller cage 120 is slightly larger than the outer diameter of the engaging shaft portion 205 of the spindle 200. With reference to FIG. 10, the annular end surface of the roller cage 120 extends spirally with a stepped portion 122. This spiral lead angle is substantially the same as the lead angle on the other end side of the coil spring 128, which will be described later. A step portion 122 is formed on one end surface of the annular shape of the roller cage 120 at a starting point extending spirally. The depth (length in the axial direction) of the step portion 122 substantially coincides with the outer diameter of the coil spring 128 described later. The other end of the coil spring 128, which will be described later, engages with the step portion 122. With reference to FIG. 9, an annular recess 123 having a diameter larger than that of the engaging shaft portion 205 of the spindle 200 is formed around the other end opening of the roller cage 120. An annular tapered surface 124 that is continuously reduced in diameter toward one end is formed from the annular recess 123.

A coil spring 128 is arranged between the spiral end surface of the roller cage 120 and the annular step portion 207 of the spindle 200, around the intermediate filament shaft portion 204 of the spindle 200. The coil spring 128 is left-handed. The coil spring 128 is configured by integrally connecting a small-diameter coil portion 130 arranged on the other end side and a large-diameter coil portion 131 arranged on one end side. The pitch of the small-diameter coil portion 130 is smaller than the pitch of the large-diameter coil portion 131. The inner diameters of the small-diameter coil portions 130 are substantially the same along the axial direction. The inner diameter of the small diameter coil portion 130 is smaller than the outer diameter of the intermediate filament shaft portion 204 of the spindle 200 in the free state. The pitch of the large-diameter coil portion 131 is larger than the pitch of the small-diameter coil portion 130. The inner diameter of the large diameter coil portion 131 is larger than the outer diameter of the intermediate diameter shaft portion 204 of the spindle 200. The inner diameter (outer diameter) of the large-diameter coil portion 131 is gradually increased toward one end side.

Then, the other end of the small-diameter coil portion 130 of the coil spring 128 is engaged with the step portion 122 of the roller cage 120, and the small-diameter coil portion 130 and the large-diameter coil portion 131 of the coil spring 128 are the intermediate filament shaft portion of the spindle 200. Wrapped around 204. As a result, the other end side of the small-diameter coil portion 130 of the coil spring 128 is wound so as to abut on one end surface of the spiral shape of the roller cage 120. Further, since the small diameter coil portion 130 of the coil spring 128 is formed to have a diameter smaller than the outer diameter of the intermediate diameter shaft portion 204 of the spindle 200, the small diameter coil portion 130 is used in the range of the small diameter coil portion 130 after assembly. , A predetermined urging force is applied toward the intermediate filament shaft portion 204 of the spindle 200. In response to this urging force, the frictional resistance between the intermediate filament portion 204 of the spindle 200 and the small diameter coil portion 130 of the coil spring 128 increases. On the other hand, the inner diameter of the large-diameter coil portion 131 of the coil spring 128 is formed to be larger than the outer diameter of the intermediate-diameter shaft portion 204 of the spindle 200. Therefore, in the range of the large-diameter coil portion 131, the intermediate-diameter shaft portion 204 There is almost no frictional resistance between the large-diameter coil portion 131 of the coil spring 128 and the intermediate-diameter shaft portion 204 of the spindle 200. Since the length of the large-diameter coil portion 131 in the axial direction after assembly is shorter than that before assembly, a state in which an urging force is applied along the axial direction, that is, the roller cage 120 and the large diameter of the spindle 200 It is assembled in a state of urging the shaft portion 203 in a direction away from the shaft portion 203 along the axial direction.

With reference to FIG. 9, a C-shaped retaining ring 135 is arranged at the other end of the annular groove portion 209 provided on the outer peripheral surface of the engaging shaft portion 205 of the spindle 200. In the free state, the retaining ring 135 is formed to have a diameter smaller than the inner diameter of the annular groove portion 209 of the engaging shaft portion 205, and when the retaining ring 135 is attached to the annular groove portion 209 of the engaging shaft portion 205. , It is mounted in a state where an urging force is applied toward the annular groove portion 209. Then, when the roller cage 120 is arranged around the engaging shaft portion 205 of the spindle 200, the retaining ring 135 comes into contact with the annular tapered surface 124 provided around the other end opening of the roller cage 120. As a result, the coil spring 128 urges the roller cage 120 to the other end side with respect to the spindle 200, but the retaining ring 135 restricts the movement of the roller cage 120 with respect to the spindle 200 in the axial direction. As a result, each roller accommodating hole 121 of the roller cage 120 and each planetary roller 76 do not come into contact with each other in the axial direction.

With reference to FIGS. 6 and 7, the nut member 210 is formed in a cylindrical shape. The nut member 210 is formed to have a length extending from the vicinity of one end surface of the large-diameter shaft portion 203 of the spindle 200 to the vicinity of the other end surface of the engaging shaft portion 205. With reference to FIG. 8, a plurality of stopper protrusions 225 extending in the axial direction and projecting in the radial direction are formed on the outer peripheral surface of the nut member 210 at intervals in the circumferential direction. Each stopper protrusion 225 extends axially on the inner peripheral surface of the cylindrical portion 20 of the piston 18 and engages with a plurality of engaging recesses 227 provided at intervals in the circumferential direction, whereby the nut member 210 is formed. Relative rotation with respect to the piston 18 and thus the caliper body 6 (cylinder portion 7) is restricted, but axial movement is allowed. With reference to FIGS. 7 and 8, a female threaded portion 230 is formed on the inner peripheral surface of the nut member 210. The female threaded portion 230 is provided over the entire axial direction of the nut member 210. The female threaded portion 230 of the nut member 210 is engaged (engaged) with each annular ridge portion 110 of each planetary roller 76.

Next, the action of the parking brake for maintaining the stopped state of the vehicle by the disc brake 1B according to the second embodiment will be described.
When the electronic control unit 38 receives an apply command (parking brake operation command) by operating the parking switch 39 or the like from the released state of the parking brake, the electric motor 35 of the motor gear unit 36 is energized to rotate the spindle 200 in the apply direction. Let me. The rotational torque transmitted to the spindle 200 is transmitted to the planetary roller 76 via the engaging portion between each annular groove portion 209 of the engaging shaft portion 205 of the spindle 200 and each annular crest portion 110 of the planetary roller 76. To. The rotational torque transmitted to the planetary roller 76 is transmitted to the nut member 210 via the engaging portion (meshing portion) between each annular crest 110 of the planetary roller 76 and the female threaded portion 230 of the nut member 210. The nut member 210 is supported by the engagement of each stopper protrusion 225 and each engagement recess 227 provided on the inner peripheral surface of the piston 18 so as not to rotate relative to the piston 18 and eventually the cylinder portion 7. In addition, each planetary roller 76 revolves in the apply direction around the axis of the nut member 210 while rotating around its own rotation axis (the roller cage 120 also rotates together), and is transmitted to the nut member 210. Axial thrust to the other end side (apply direction) is generated according to the rotational torque applied. The nut member 210 that has received the axial thrust toward the other end moves toward the other end (apply direction) along the axial direction and presses the inclined portion 31 of the bottom 19 of the piston 18. As a result, the piston 18 moves to the other end side and presses the inner brake pad 2. As a result, the disc rotor D is pressed by the inner and outer brake pads 2 and 3, and a braking force of the vehicle is generated.

At the time of this application, in the stage before pressing the disc rotor D by the inner and outer brake pads 2 and 3, the reaction force from the pressing force on the disc rotor D by the inner and outer brake pads 2 and 3 is not applied, so that the spindle The rotational torque of 200 is small. Therefore, in the stage before pressing the disc rotor D by the inner and outer brake pads 2 and 3, when the spindle 200 rotates in the apply direction, the other end of the coil spring 128 engages with the step portion 122 of the roller cage 120. Further, frictional resistance between the intermediate diameter shaft portion 204 of the spindle 200 and the small diameter coil portion 130 of the coil spring 128 is also provided, and the required relative rotational torque between the spindle 200 and the roller cage 120 is not reached. Therefore, the spindle 200, the coil spring 128, and the roller cage 120 (including each planetary roller 76) rotate together as one. As a result, at this stage, the roller screw mechanism 46 acts as a fast-forward screw mechanism, so that the time from the start of application to the pressing of the disc rotor D by the inner and outer brake pads 2 and 3 can be shortened.

Subsequently, when the braking force generating region for pressing the disc rotor D by the inner and outer brake pads 2 and 3 is reached, the reaction force (along the axial direction) from the pressing force on the disc rotor D by the inner and outer brake pads 2 and 3 is reached. Reaction force) is applied to the roller screw mechanism 46. Then, when the required relative rotational torque between the intermediate diameter shaft portion 204 of the spindle 200 and the roller cage 120 is exceeded, the diameter of the small diameter coil portion 130 of the coil spring 128 is expanded, and the diameter of the small diameter coil portion 130 of the coil spring 128 and the spindle 200 are increased. The frictional force with the intermediate diameter shaft portion 204 of the above is reduced. As a result, the spindle 200 and the roller cage 120 easily rotate relative to each other, in other words, the roller screw mechanism 46 decelerates the planet, resulting in a high screw efficiency of 50% or more, and the other end side of the nut member 210. The driving force to is increased. Then, when the electronic control unit 38 stops energizing the electric motor 35, first, the roller screw mechanism 46 tries to reversely operate due to the reaction force from the disc rotor D, and the shaft member 75 tries to rotate in the release direction. At this time, since each planetary roller 76 tries to rotate (relatively rotate) with a delay with respect to the shaft member 75 due to the planetary deceleration motion, each planetary roller 76 comes into contact with the roller accommodating hole 121 in the circumferential direction. However, in order for the roller cage 120 to rotate relative to the shaft member 75, it must move to the other end side along the lead angle of the coil spring 128. Relative rotation is not possible. In other words, the roller screw mechanism 46 cannot decelerate the planet in the release direction, and the screw has a low efficiency of less than 0, so that the stopped state can be maintained.

On the other hand, when the electronic control unit 38 receives a release command (parking brake release command) such as an operation of the parking switch 39, the electric motor 35 of the motor gear unit 36 is energized to rotate the spindle 200 in the release direction. When the spindle 200 rotates in the release direction, the roller cage 120 cannot move in the axial direction, so that the spindle 200, the coil spring 128, and the roller cage 120 rotate together in the release direction. Subsequently, the rotational torque transmitted to the spindle 200 is transmitted to the planetary roller 76 via the coil spring 128 and the roller cage 120. The rotational torque transmitted to the planetary roller 76 is transmitted to the nut member 210 via the engaging portion (meshing portion) between each annular ridge 110 of each planetary roller 76 and each female thread 230 of the nut member 210. To. Since the nut member 210 is supported by the engagement of each stopper protrusion 225 and each engagement recess 227 provided on the inner peripheral surface of the piston 10 with respect to the piston 18 and eventually the cylinder portion 7 so as not to rotate relative to each other. Each planetary roller 76 revolves around the axis of the nut member 210 in the release direction while the annular ridge 110 and the female thread 230 slide (the roller cage 120 also rotates). At the time of this release, the roller screw mechanism 46 acts as a low-efficiency fast-forward screw mechanism by integrally rotating each planetary roller 76 together with the roller cage 120 with the spindle 200 without decelerating the planet, and the nut member 210. Moves in the release direction. Then, the pressing force of the disc rotor D by the inner and outer brake pads 2 and 3 is released.

The disc brake 1B according to the second embodiment described above employs the shaft member 75 that constitutes the sliding screw engaging portion 45 with the spindle 48, which is adopted for the disc brake 1A according to the first embodiment. Since there is no such component, the number of parts can be reduced, leading to a reduction in manufacturing cost. Further, at the time of application, the roller screw mechanism 46 having low screw efficiency acts as a fast-forward screw mechanism before pressing the disc rotor D by the inner and outer brake pads 2 and 3, and then the inner and outer brake pads 2 When the braking force generating region for pressing the disc rotor D is reached by 3, the spindle 200 and the roller cage 120 rotate relative to each other, in other words, the roller screw mechanism 46 makes a planetary deceleration motion, and the screw efficiency is 50% or more. The efficiency is high, and the propulsive force toward the other end of the nut member 210 can be increased. On the other hand, at the time of release, the roller screw mechanism 46 also acts as a low-efficiency fast-forward screw mechanism by rotating each planetary roller 76 together with the roller cage 120 together with the spindle 200 without decelerating the planet. The nut member 210 moves in the release direction. As a result, the variation in the release operation time can be suppressed, and the feeling at the time of auto release can be improved. In this way, in the disc brake 1B according to the second embodiment, the roller screw mechanism 46 acts as a fast-forward screw mechanism at the time of applying and releasing, so that the variation in the applying operating time and the releasing operating time is suppressed, and further, the applying is further suppressed. The operating time and release operating time can be shortened.

1A, 1B disc brake, 2 inner brake pad (pad), 3 outer brake pad (pad), 4 caliper, 6 caliper body, 10 cylinder, 18 piston, 35 electric motor (motor), 37 piston propulsion mechanism (rotary linear motion) Conversion mechanism), 48 spindle, 75 shaft member (shaft member), 76 planetary roller (rolling element), 77, 210 nut member (cylindrical member), 120 cage roller, 121 roller accommodating hole, 128 coil spring (coil-shaped member, Clutch member, elastic body), 135 retaining ring (locking member), 200 spindle (shaft member), D disc rotor (rotor)

Claims (4)

A pair of pads arranged on both sides of the rotor in the axial direction with the rotor in between,
A piston that presses one of the pair of pads against the rotor,
A caliper body having a cylinder into which the piston is slidably fitted,
The motor provided in the caliper body and
The caliper main body is provided with a rotary linear motion conversion mechanism that converts the rotary motion of the motor into a linear motion to propel the piston.
The rotary linear motion conversion mechanism
Cylindrical member and
A shaft member arranged radially inside the tubular member and
A plurality of rolling elements are arranged between the shaft member and the tubular member at intervals in the circumferential direction, and are engaged with the shaft member and the tubular member.
A roller cage that is arranged between the shaft member and the tubular member and is provided with a plurality of accommodating holes for accommodating the rolling elements along the circumferential direction.
It is wound around the outer peripheral surface of the shaft member, one end of which abuts on the axial end of the roller cage, the other end side has a larger diameter than the one end side, and the other end side has a larger pitch than the one end side. With coiled members
A disc brake characterized by being equipped with. The disc brake according to claim 1, wherein a locking member for restricting relative movement along the axial direction is provided between the roller cage and the shaft member. A pair of pads arranged on both sides of the rotor in the axial direction with the rotor in between,
A piston that presses one of the pair of pads against the rotor,
A caliper body having a cylinder into which the piston is slidably fitted,
The motor provided in the caliper body and
The caliper main body is provided with a rotary linear motion conversion mechanism that converts the rotary motion of the motor into a linear motion to propel the piston.
The rotary linear motion conversion mechanism
Cylindrical member and
A shaft member arranged radially inside the tubular member and
A plurality of rolling elements are arranged between the shaft member and the tubular member at intervals in the circumferential direction, and are engaged with the shaft member and the tubular member.
A roller cage that is arranged between the shaft member and the tubular member and is provided with a plurality of accommodating holes for accommodating the rolling elements along the circumferential direction.
A clutch member that switches between relative rotation or integral rotation of the shaft member and the roller cage according to the rotation direction of the shaft member.
A disc brake characterized by being equipped with. The disc brake according to claim 3, wherein the clutch member is an elastic body that urges the roller cage with respect to the shaft member in the axial direction.

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