JP7190412B2 - disc brake - Google Patents

Description

The present invention relates to disc brakes used for braking vehicles.

Disc brakes with electric parking brakes are known as braking devices for vehicles. For example, the disc brake described in Patent Document 1 includes a piston propulsion mechanism that converts the rotational motion of a motor gear unit into 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 threadedly engaged with the spindle rod, a ring shaft supported on the bottom surface of the cylinder so as not to rotate relative to each other, and an adjuster nut. a plurality of planetary rods disposed between the ring shaft.

WO2018/003393 Pamphlet

However, in the piston propulsion mechanism described in Patent Literature 1 described above, the release operation time when releasing the parking brake may vary greatly. As a result, as a vehicle system, there is a possibility that the feeling at the time of auto-release (release of the accelerator) may be deteriorated. One of the causes of this 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 actuate the first screw fitting portion between the male threaded portion of the spindle and the female threaded portion of the adjuster nut is applied at the engagement portion between each planetary roller, the adjuster nut and the nut member. When it is generated, the first screw fitting portion is tightened by the axial reaction force that is generated at the same time, and the operation starting torque of the first screw fitting portion increases. Since the magnitude of the tightening force associated with the axial reaction force at the first screw fitting portion amplifies the variation in the frictional force at the first screw fitting portion, as a result, it is necessary Variation in operating torque is amplified until it exceeds variation in frictional force in the first screw fitting portion. For this reason, the operation start time of the piston propulsion mechanism is not stable, and the release operation time varies for each operation.

Another object of the present invention is to provide a disc brake that reduces variations in the release operation time of the electric parking brake, thereby improving the feel during auto-release.

A first disc brake according to the present invention includes a pair of pads arranged on both sides of the rotor in the axial direction across the rotor, a piston for pressing one of the pair of pads against the rotor, and the piston A caliper body having a cylinder slidably fitted thereon, a motor provided in the caliper body, and a rotary/linear motion provided in the caliper body that converts the rotary motion of the motor into linear motion to propel the piston. a conversion mechanism, wherein the rotation-to-linear motion conversion mechanism includes a tubular member, a shaft member disposed radially inside the tubular member, and a circumferential force between the shaft member and the tubular member. a plurality of rolling elements arranged at intervals in a direction and engaged with the shaft member and the cylindrical member; a plurality of roller cages provided along the circumferential direction, and a roller cage wound around the outer peripheral surface of the shaft member, one end of which is in contact with the axial end of the roller cage, and the other end of which has a larger diameter than the one end, and a coil-shaped member formed with a larger pitch on the other end side than on the one end side.

A second disc brake according to the present invention includes a pair of pads arranged on both sides of the rotor in the axial direction across the rotor, a piston for pressing one of the pair of pads against the rotor, and the A caliper body having a cylinder in which the piston is slidably fitted, a motor provided in the caliper body, and a rotation provided in the caliper body that converts the rotary motion of the motor into linear motion to propel the piston. a linear motion conversion mechanism, wherein the rotation/linear motion conversion mechanism includes 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 thereof and are engaged with the shaft member and the tubular member, and a rolling element is arranged between the shaft member and the tubular member to accommodate the rolling elements. A roller cage having a plurality of housing holes along the circumferential direction, and a clutch member for switching relative rotation or integral rotation between the shaft member and the roller cage according to the rotation direction of the shaft member. and

According to the disc brake of the present invention, it is possible to reduce the variation in the release operation time of the electric parking brake, and improve the feel during auto-release.

Sectional drawing of the disc brake which concerns on 1st Embodiment. FIG. 2 is an enlarged view of a main portion of FIG. 1; FIG. 2 is an exploded perspective view of a piston propulsion mechanism in the disc brake of FIG. 1; (a) is a plan view from one end side of an assembly state of a shaft member, a coil spring, and a roller cage in the disc brake of FIG. 1, and (b) is a cross section along line AA of (a). (a) is a side view in which one end of the coil spring can be seen in an 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 seen. . Sectional drawing of the disc brake which concerns on 2nd Embodiment. FIG. 7 is an enlarged view of a main portion of FIG. 6; FIG. 7 is an exploded perspective view of a piston propulsion mechanism in the disc brake of FIG. 6; FIG. 7(a) is a plan view from the other end side of a state in which a coil spring and a roller cage are assembled to a spindle in the disc brake of FIG. 6, and (b) is a cross section along line BB of (a). (a) is a side view in which the other end of the coil spring can be seen with the coil spring and roller cage 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 seen. .

Disc brakes 1A and 1B according to first and second embodiments will be described in detail below with reference to FIGS. 1 to 10, respectively. 1, 2, 6 and 7 will be referred to as one end side of the disc brakes 1A and 1B according to the first and second embodiments for convenience of explanation. And 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. 1, 2, 6 and 7 is the axial direction of the disc brakes 1A and 1B according to the first and second embodiments.

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

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

The piston 18 is shaped like a cup consisting of 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 axially slidably fitted in the large-diameter opening 10A of the cylinder 10 . The outer peripheral surface of the cylindrical portion 20 of the piston 18 contacts the piston seal 16 . A hydraulic chamber 21 defined by the piston seal 16 is formed between the piston 18 and the bottom 13 of the cylinder 10 . Hydraulic pressure is supplied to the hydraulic pressure chamber 21 from a hydraulic pressure source (not shown) such as a master cylinder or a hydraulic pressure control unit through 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 becomes non-rotatable relative to the cylinder 10 and, by extension, the caliper body 6 . A dust boot 27 is provided between the bottom portion 19 of the piston 18 and the large diameter opening 10A of the cylinder 10 . A circular concave portion 30 located in the center in the radial direction and an annular inclined portion 31 that is continuous with the circular concave portion 30 and whose diameter increases toward the one end side are formed on the inner surface of the bottom portion 19 of the piston 18 on the one end side. , is formed.

The caliper body 6 is provided with a motor gear unit 36 containing an electric motor 35 and a speed 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 linear motion to propel the piston 18 (moves it to the other end) and holds the piston 18 at 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 is connected to the electronic control unit 38 to be operated when the parking brake is turned ON/OFF. It should be noted that the electronic control unit 38 can operate the parking brake based on a signal from the vehicle side without operating the parking switch 39 . Also, the reduction mechanism of the motor gear unit 36 includes, for example, a spur-tooth multistage reduction mechanism and a planetary gear reduction mechanism.

2 and 3, the piston driving mechanism 37 includes a spindle 48, a sliding screw engaging portion 45, and a roller screw mechanism 46. As shown in FIG. The spindle 48 includes a shaft portion 49 formed on one end side, a male thread portion 50 formed on the other end side, and a flange portion 51 formed between the shaft portion 49 and the male thread portion 50. . A polygonal shaft portion 53 is formed at one end of the shaft portion 49 of the spindle 48 . In this embodiment, the polygonal shaft portion 53 is formed as a hexagonal shaft portion. The polygonal shaft portion 53 is connected to the reduction mechanism of the motor gear unit 36 (for example, the carrier of the planetary reduction gear mechanism, etc.) so as not to rotate relative to each other. Rotational torque from the motor gear unit 36 is thereby transmitted to the spindle 48 . The connection between the shaft portion 49 of the spindle 48 and the speed reduction mechanism of the motor gear unit 36 uses a mechanical element capable of transmitting rotational torque, such as a spline, a key, etc., in addition to the rotation stop by the polygonal shaft portion 53 described above. be able to. The externally threaded portion 50 of the spindle 48 is positioned with its other end adjacent to a circular recess 30 provided in the bottom 19 of the piston 18 . The flange portion 51 is annular and protrudes radially outward. A rolling concave surface 54 for the thrust ball 65 is formed on one end surface of the flange portion 51 of the spindle 48 . A plurality of projections 55 are formed on the other end surface of the flange portion 51 of the spindle 48 at intervals along the circumferential direction.

A bottom portion 13 of the cylinder 10 is formed with a shaft hole 12 through which the shaft portion 49 of the spindle 48 is inserted. A guide sleeve 56 is fitted to the inner peripheral surface of the shaft hole 12 . A shaft portion 49 of the spindle 48 is rotatably supported by the caliper body 6 via the guide sleeve 56 . A seal ring 57 seals between the shaft hole 12 of the cylinder 10 and the shaft portion 49 of the spindle 48 . The seal ring 57 is arranged on the other end side of the guide sleeve 56 . A base plate 60 is positioned within the cylinder 10 near its bottom 13 . The base plate 60 is formed in an annular plate shape 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 a 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 the 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 through the shaft hole 61 of the base plate 60 . A rolling concave surface 63 for a thrust ball 65 is formed on the other end surface of the base plate 60 . A plurality of thrust balls 65 are rotatably arranged between a rolling concave surface 54 provided on one end surface of the flange portion 51 of the spindle 48 and a rolling concave surface 63 provided on the other end surface of the base plate 60 . A plurality of thrust balls 65 are held by retainers 66 at regular intervals in the circumferential direction.

An inclined surface 68 whose diameter is reduced toward the one end side is formed on the one end outer peripheral surface of the base plate 60 . A C-shaped retaining ring 70 is mounted between the inclined surface 68 of the base plate 60 and a retaining groove portion 158 of a nut member 77, which will be described later. The retaining ring 70 restricts the base plate 60 from moving toward one end of the nut member 77, in other words, biases the base plate 60 toward the other end. 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 (reduced diameter) state. A plurality of cutouts 71 (see FIG. 3) are formed on the outer peripheral surface of the base plate 60 for axially circulating the brake fluid.

The sliding screw engaging portion 45 is configured by a threaded portion between the male threaded portion 50 of the spindle 48 and the female threaded portion 84 of the shaft member 75 to be described later. The slide 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 slip screw engaging portion 45 has a reverse efficiency set to 0 or less, and the axial thrust acting on the shaft member 75 cannot rotate the spindle 48 . That is, the sliding screw engaging portion 45 can convert the rotational torque of the spindle 48 into axial thrust force on the shaft member 75 , but the axial thrust force of the shaft member 75 is 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 cylindrical member. The shaft member 75 is formed cylindrical. A 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 projections 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 projections 82 provided on the shaft member 75 and the plurality of projections 55 provided on the other end surface of the flange portion 51 of the spindle 48 interfere with each other, relative rotation of the two is restricted. This prevents the spindle 48 (male threaded portion 50) from sticking (biting) due to excessive screwing into the shaft member 75 (female threaded portion 84).

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

A thrust plate 92 is arranged to face the other end face 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 through which the male threaded 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 cutouts 95 (see FIG. 3) are formed on the outer peripheral surface of the thrust plate 92 for axially circulating the brake fluid. A contact surface 94 is formed on the other end surface of the thrust plate 92 to contact the inclined portion 31 provided on the bottom portion 19 of the piston 18 . A rolling concave surface 97 for a thrust ball 99 is formed on one end surface of the thrust plate 92 . 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). A plurality of thrust balls 99 are held by a retainer 100 at regular intervals in the circumferential direction.

A bearing holder 103 is inserted from the inner peripheral surface of the shaft hole 93 of the thrust plate 92 to the inside of 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 projecting radially outward is formed on the outer peripheral surface of the other end of the bearing holder 103 . The bearing holder 103 has two elastic pieces 106 provided on its outer peripheral surface at a pitch of 180°. Each elastic piece 106 is formed by cutting the outer peripheral wall of the bearing holder 103 . A locking claw portion 107 is provided at the tip of each elastic piece 106 so as to protrude radially outward. The locking claw portion 107 can be projected and retracted from the outer peripheral surface of the bearing holder 103 along the radial direction by elastically deforming the elastic piece 106 . The annular locking portion 105 of the bearing holder 103 abuts against the other end surface of the thrust plate 92 , and the locking claw portion 107 of each elastic piece 106 is inserted into the communicating hole 86 of the large-diameter shaft portion 80 . Engaged from the inside. The bearing holder 103 allows the thrust plate 92 and the thrust ball 99 including the retainer 100 to be integrally held at the other end of the shaft member 75 .

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

As shown in FIGS. 2-4, the roller cage 120 holds each planetary roller 76 so that adjacent planetary rollers 76 do not interfere with each other. The roller cage 120 is supported around the shaft member 75 so as to be rotatable relative to the shaft member 75 and axially slidable relative to a nut member 77 which will be described later. 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 housing holes 121 for housing the 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 housing holes 121 are formed corresponding to the number of planetary rollers 76 . In this embodiment, six roller housing holes 121 are formed corresponding to the number of planetary rollers 76 .

The roller housing hole 121 is formed in a substantially rectangular shape elongated in the axial direction. The roller accommodation hole 121 regulates the position of the planetary roller 76 in the circumferential direction, but the roller accommodation hole 121 and the planetary roller 76 do not come into contact with each other in the axial direction. Referring also to FIG. 5 , the other annular end surface of roller cage 120 extends spirally having a stepped portion 122 . The spiral lead angle is substantially the same as the lead angle of one end side (small-diameter coil portion 130) of the coil spring 128, which will be described later. Referring also to FIG. 5( a ), the other annular end surface of roller cage 120 is formed with stepped portion 122 at the end point extending spirally. The depth (length in the axial direction) of the stepped portion 122 substantially matches the outer diameter of the coil spring 128, which will be described later. One end of a coil spring 128 to be described later is engaged with the stepped portion 122 . 4A, an annular recess 123 having a larger diameter than the small-diameter shaft portion 79 of the shaft member 75 is formed around the one end opening of the roller cage 120. As shown in FIG. An annular tapered surface 124 is formed continuously from the annular recess 123 and has a diameter reduced toward the other end. When the planetary rollers 76 are accommodated in the respective roller accommodating holes 121, the peripheral wall portion of the roller cage 120 and the circular shape connecting the centers of the planetary rollers 76 in the radial direction are substantially aligned. As a result, the rolling of the roller cage 120 into the engaging portion between the planetary rollers 76 and the shaft member 75 and the engaging portion between the planetary rollers 76 and the nut member 77 is suppressed. Position can be held.

2, 4 and 5, the small-diameter shaft portion 79 of the shaft member 75 ( A coil spring 128 is arranged around the area where each annular groove 83 is not formed. When the shaft member 75 rotates in the applying direction, the coil spring 128 keeps the shaft member 75, the coil spring 128, and the rollers 128 until the required relative 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 the required relative torque is exceeded, the relative rotation between the shaft member 75 and the roller cage 120 is accelerated. It is configured to integrally rotate the coil spring 128 and the roller cage 120 . The coil spring 128 corresponds to a coil-shaped member or a clutch member.

The coil springs 128 are elastic bodies and are arranged at uneven pitches. In this embodiment, the coil spring 128 is configured with a right-handed winding, but may be configured with a left-handed winding depending on 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 larger diameter than 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 small-diameter coil portion 130 has substantially the same inner diameter along the axial direction. The inner diameter of the small-diameter coil portion 130 in the free state is smaller than the outer diameter of the small-diameter shaft portion 79 of the shaft member 75 (outside the range where each annular groove portion 83 is formed). The small-diameter coil portion 130 has three turns in the present embodiment, and is formed in close contact in the axial direction, but the number of turns and the pitch may be changed according to 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 gradually expands toward the other end. The free length (length in the axial direction before assembly) of the large-diameter coil portion 131 is formed longer than the length after assembly. Although the large-diameter coil portion 131 has one turn in this embodiment, it may be changed according to design requirements.

4 and 5, one 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 of the coil spring 128 are engaged with each other. 131 is around the small-diameter shaft portion 79 of the shaft member 75 and is wound outside the range where 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 come into contact with the spiral other end surface of the roller cage 120 . In addition, since the small-diameter coil portion 130 of the coil spring 128 is formed to have a smaller diameter than the outer diameter of the small-diameter shaft portion 79 of the shaft member 75, the small-diameter coil portion 130 does not move the small-diameter coil portion 130 after assembly. , a predetermined biasing force is applied toward the small-diameter shaft portion 79 . Corresponding to this biasing force, 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, 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 . Since they are in a slightly floating state, 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 large-diameter coil portion 131 has a shorter axial length after assembly than before assembly, it is in a state in which a biasing force is applied along the axial direction, that is, when 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 it along the axial direction.

As can be seen from FIG. 4B, a C-shaped retaining ring 135 is arranged at one end of an 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 has a smaller diameter than the inner diameter of the annular groove portion 83 of the small-diameter shaft portion 79 . It is mounted with a biasing force 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, a retaining ring 135 is provided around one end opening of the roller cage 120. It abuts against the annular tapered surface 124 .

As a result, the coil spring 128 urges the roller cage 120 toward one end of the shaft member 75 , but the retaining ring 135 restricts axial movement of the roller cage 120 with respect to the shaft member 75 . As a result, the roller housing holes 121 of the roller cage 120 and the planetary rollers 76 do not contact each other in the axial direction. Retaining ring 135 corresponds to a locking member that restricts axial relative movement between shaft member 75 and roller cage 120 . Conventionally, a coil-shaped one-way clutch or the like generally has a configuration in which the winding end of the coil portion is formed into 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 increases. was required, and there was a problem of increasing in size. However, since the coil spring 128 according to the present embodiment does not have the hook portion, it is possible to achieve miniaturization. The action of this coil spring 128 will be described later in detail.

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. Referring to FIG. 3, a stopper protrusion 160 protrudes from one end face of large-diameter nut portion 151 toward the one end side. The stopper protrusions 160, 160 are formed 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, 160 are engaged with engagement recesses provided in the bottom portion 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 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 . In the large-diameter nut portion 151, a plurality of passages 157 are provided at intervals along the circumferential direction so as to pass through the peripheral wall portion in the radial direction and circulate the brake fluid. An annular retaining groove portion 158 to which the retaining ring 70 is attached 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 threaded portion 155 is formed on the inner peripheral surface of the small diameter nut portion 152 . The female threaded portion 155 is provided over substantially the entire axial region of the small-diameter nut portion 152 .

The female threaded portion 155 of the nut member 77 is engaged (engaged) with each annular peak portion 110 of each planetary roller 76 . The female screw portion 155 of the nut member 77 and the annular ridge portions 110 of the planetary roller 76 have the same pitch (axial interval) between the female screw portion 155 and the annular ridge portions 110, and the female screw portion 155 has the same pitch. By setting the number of threads to an integral multiple of the number of planetary rollers 76, they are meshed with each other. For example, when six planetary rollers 76 are used and the pitch of the female threaded portion 155 and each annular ridge portion 110 is set to 1 mm, the number of threads of the female threaded portion 155 is set to 6 (6 x 1). , the female threaded portion 155 of the nut member 77 and the annular ridges 110 of the planetary roller 76 can be meshed with each other. Note that the lead at this time is 6 mm.

Next, the action of the disc brake 1A of the first embodiment will be described.
When the driver depresses the brake pedal (not shown), the hydraulic pressure corresponding to the force applied to the brake pedal is applied to the caliper body 6 (cylinder 10) via the master cylinder and the hydraulic circuit (not shown). It is supplied to the hydraulic chamber 21 . As a result, the piston 18 moves from its original position during 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, which is in contact with the claw portion 8, against the disc rotor D. As shown in FIG. As a result, the disk rotor D is sandwiched between the pair of inner and outer brake pads 2 and 3 to generate a frictional force, thereby generating braking force for the vehicle.

On the other hand, when the driver releases the brake pedal, the supply of hydraulic pressure from the master cylinder to the hydraulic pressure chamber 21 is stopped, and the hydraulic pressure in the hydraulic pressure chamber 21 decreases. 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 as the inner and outer brake pads 2, 3 wear and the limit of elastic deformation of the piston seal 16 is exceeded, slippage occurs between the piston 18 and the piston seal 16. , the original position of the piston 18 relative to the caliper body 6 is moved by the slippage. Thereby, even when the inner and outer brake pads 2, 3 are worn, the pad clearance is adjusted to be constant.

Next, the operation of the parking brake that maintains 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 activation command) by operating the parking switch 39 or the like from the parking brake released state, the electric motor 35 of the motor gear unit 36 is energized to rotate the spindle 48 in the apply direction. Let The rotational torque transmitted to the spindle 48 is transmitted to the shaft member 75 (roller screw mechanism 46 ) via the slide screw engagement portion 45 between the male threaded portion 50 of the spindle 48 and the female threaded portion 84 of the shaft member 75 . Since the rotation torque transmitted from the spindle 48 is given to the shaft member 75 as a reaction force by the rotation resistance torque from each planetary roller 76, the shaft member 75 rotates relative to the spindle 48. At the same time, an axial thrust toward the other end (apply direction) is applied.

The rotational torque transmitted to the shaft member 75 (roller screw mechanism 46) is transmitted to the planetary roller 76 via the engaging portions between the annular grooves 83 of the shaft member 75 and the annular ridges 110 of the planetary roller 76. transmitted. The rotational torque transmitted to the planetary roller 76 is transmitted to the nut member 77 via the engaging portions (meshing portions) between the annular ridges 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 engaging the stopper protrusions 160 and 160 with the accommodation recesses, each planetary roller 76 rotates its own rotating shaft. It revolves in the apply direction around the axis of the nut member 77 while rotating about its axis (the roller cage 120 also rotates together). At this time, each planetary roller 76 generates an axial thrust toward the other end in accordance with the transmitted rotational torque. The thrust force generated in each planetary roller 76 is transmitted to the shaft member 75 via the engaging portions between the annular ridges 110 of the planetary rollers 76 and the annular grooves 83 of the shaft member 75 . As a result, the shaft member 75 rotates and moves toward the other end (apply direction).

At the slide screw engaging portion 45 between the male threaded portion 50 of the spindle 48 and the female threaded portion 84 of the shaft member 75 , a rotational torque substantially equal to the rotational torque transmitted from the shaft member 75 to the planetary roller 76 is applied to the spindle 48 . to the shaft member 75. Therefore, as described above, an axial thrust toward the other end is generated in the slide screw engaging portion 45 according to the transmission torque. Due to the axial thrust generated in the slide screw engaging portion 45 , the shaft member 75 receives an axial thrust toward the other end of the spindle 48 . In this way, the shaft member 75 is driven by the axial thrust toward the other end due to the rotational torque transmitted from the spindle 48 at the slide screw engaging portion 45 and the force generated by the nut member 77 of the roller screw mechanism 46 and each planetary roller 76 . It receives an axial thrust that is the sum of the axial thrust toward the other end generated between them.

The shaft member 75 that receives the axial thrust toward the other end (apply direction) rotates along the female threaded portion 155 of the nut member 77 and moves toward the other end (apply direction). , 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 (apply direction) and presses the inner brake pad 2 . As a result, the disk rotor D is pressed by the inner and outer brake pads 2 and 3, and 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 with which the shaft member 75 presses the piston 18, in other words, the braking force of the vehicle reaches a predetermined value. , stop the driving (rotation) of the spindle 48 in the applying direction. Note that the electronic control unit 38 can calculate the force with which the shaft member 75 presses the piston 18 (thrust force of the shaft member 75) based on the current value of the electric motor 35, for example.

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

Subsequently, when the braking force generation region in which the inner and outer brake pads 2 and 3 press the disc rotor D is reached, the reaction force from the pressing force to the disc rotor D by the inner and outer brake pads 2 and 3 (along the axial direction 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. 79 is reduced. As a result, the shaft member 75 and the roller cage 120 are easily rotated relative to each other. The propulsive force to the side is increased. The magnitude of the relative rotational torque required between the shaft member 75 and the roller cage 120 can be appropriately adjusted by 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 are rotated. Since the frictional force with the portion 79 is reduced, the roller cage 120 can be easily urged toward one end 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 respective gaps along the axial direction of the coil spring 128, the roller cage 120 and the retaining ring 135 can be eliminated. As a result, it is not affected by dimensional variation (deterioration) due to wear of contact portions of the members, as well as dimensional variations during part manufacturing.

Further, as described above, since the slip screw engaging portion 45 has a reverse efficiency of 0 or less, it can convert the rotational torque of the spindle 48 into an axial thrust toward the other end of the shaft member 75. Axial thrust to the shaft member 75 cannot be converted into 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 if the reaction force of the pressing force from the disk rotor D acts via the piston 18. be able to. As a result, the piston 18 is held in the braking position and the parking brake operation is completed. When the parking brake is fully activated, the reaction force of the pressing force from the disk rotor D is applied to the caliper body 6 via the thrust plate 92, thrust balls 99, shaft member 75, spindle 48, thrust balls 65, and base plate 60. is transmitted to the bottom portion 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 operation of the parking switch 39, it energizes the electric motor 35 of the motor gear unit 36 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 threaded portion 50 of the spindle 48 and the female threaded portion 84 of the shaft member 75, and the shaft member 75 is The inner and outer brake pads 2 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). , 3 to the disk rotor D is substantially eliminated. That is, the starting torque of the slide screw engaging portion 45 between the male threaded portion 50 of the spindle 48 and the female threaded portion 84 of the shaft member 75 is set to be larger than the starting torque of the roller screw mechanism 46 functioning as a rapid feed screw mechanism. is set to Therefore, when releasing, the roller screw mechanism 46 operates before the sliding screw engagement portion 45 , so that when the spindle 48 is rotated in the releasing direction, the shaft member 75 rotates integrally with the spindle 48 . Then, each annular groove portion 83 of the shaft member 75, each annular peak portion 110 of the planetary roller 76, and the female thread portion 155 of the nut member 77 are engaged in the releasing direction. Further, when the shaft member 75 rotates, the roller screw mechanism 46 tries to perform a planetary deceleration motion, and each planetary roller 76 comes into contact with the roller housing hole 121 in the circumferential direction.

At this time, the roller cage 120 attempts to rotate (relatively rotate) with respect to the shaft member 75 with a delay, and attempts to move toward one end along the lead angle of the coil spring 128 . However, since the roller cage 120 is restricted from moving toward one end by the retaining ring 135, the roller cage 120 cannot relatively rotate. Thus, when the shaft member 75 rotates in the release direction, the roller cage 120 cannot move in the axial direction, so the shaft member 75, the coil spring 128, and the roller cage 120 (including the planetary rollers 76) are united to release. rotate in the direction Subsequently, the rotational torque transmitted to shaft member 75 is transmitted to planetary roller 76 via coil spring 128 and roller cage 120 .

The rotational torque transmitted to the planetary rollers 76 is transmitted to the nut member 77 via the engaging portions (meshing portions) between the annular ridges 110 of the planetary rollers 76 and the female threads 155 of the nut member 77. be. The nut member 77 is supported so as not to rotate relative to the cylinder portion 7 by engaging the stopper projections 160 and 160 with the accommodation recesses. 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 rotates together). At this time, each planetary roller 76 generates axial thrust in the release direction according to the transmitted rotational torque. The axial thrust force generated in each planetary roller 76 is transmitted to the shaft member 75 via the engagement portion between each annular peak portion 110 of each planetary roller 76 and each annular groove portion 83 of the shaft member 75 .

When the roller screw mechanism 46 is released, the planetary rollers 76 rotate integrally with the shaft member 75 together with the roller cage 120 without performing a planetary deceleration motion. 75 moves relative to the nut member 77 in the release direction. At this time, since the roller screw mechanism 46 acts as a screw mechanism with low efficiency, the axial force generated with respect to the applied rotational torque is reduced. As a result, the force that tightens the slide screw engaging portion 45 generated by the operation of the roller screw mechanism 46 can be suppressed. In this way, at the time of release, the efficiency of the roller screw mechanism 46 is reduced, and the rotation torque input from the motor gear unit 36 to the spindle 48 is applied to the slide 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 releasing direction from the braking force generation area where the disc rotor D is pressed by the inner and outer brake pads 2 and 3, and slips against the rotational torque input from the motor gear unit 36 to the spindle 48. When the operating torque of the screw engagement 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. do. When releasing, the roller screw mechanism 46 operates as a rapid feed screw mechanism regardless of the presence or absence of a reaction force from the pressing force of the inner and outer brake pads 2, 3 on the disc rotor D, thereby shortening the release operation time. can do.

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 portion 19 of the piston 18 and the contact surface 94 of the thrust plate 92, the motor gear unit 36 is stopped. During the release operation, the shaft member 75 moves toward one end while rotating relative to the spindle 48 , and the protrusion 82 formed on one end surface of the shaft member 75 is positioned on the other end surface of the flange portion 51 of the spindle 48 . By being engaged with the convex portion 55 , relative rotation of the shaft member 75 with respect to the spindle 48 is restricted. 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, it is wound around the outer peripheral surface of the small-diameter shaft portion 79 of the shaft member 75 (outside the range where each annular groove portion 83 is formed), and one end of the shaft member 75 is wound around the roller cage. A coil spring 128 abuts against a stepped portion 122 on the other end surface of 120 and has a larger diameter on the other end side than the one end side and a larger pitch on the other end side than the one end side.

As a result, when the shaft member 75 rotates, the coil spring 128 and the roller cage 120 are integrally rotated together with the shaft member 75 in the stage before the disk rotor D is pressed by the inner and outer brake pads 2 and 3 at the time of application. do. As a result, at this stage, the roller screw mechanism 46 acts as a rapid feed screw mechanism, so the time from the start of applying to the disc rotor D being pressed by the inner and outer brake pads 2, 3 can be shortened. After that, the inner and outer brake pads 2, 3 reach the braking force generating region where the disk rotor D is pressed, and the reaction force from the pressing force on the disk rotor D by the inner and outer brake pads 2, 3 ) is applied to the roller screw mechanism 46, the shaft member 75 and the roller cage 120 will easily rotate relative to each other when the required relative rotational torque between the shaft member 75 and the roller cage 120 is exceeded. First, in other words, the roller screw mechanism 46 undergoes a planetary deceleration motion, the screw efficiency becomes as high as 50% or more, and the driving force toward the other end of the shaft member 75 is increased.

On the other hand, when the roller screw mechanism 46 is released, the planetary rollers 76 rotate integrally with the shaft member 75 together with the roller cage 120 without planetary deceleration motion. A member 75 can be moved relative to the nut member 77 in a release direction. In addition, since the roller screw mechanism 46 acts as a screw mechanism with low efficiency, it is possible to reduce the axial force generated with respect to the applied rotational torque. The force for tightening the slide screw engaging portion 45 can be kept small. In this way, at the time of release, the efficiency of the roller screw mechanism 46 is reduced, and the rotation torque input from the motor gear unit 36 to the spindle 48 is applied to the slide screw engaging portion 45 as the roller screw mechanism 46 operates. The generated axial force can be suppressed. As a result, it is possible to reduce the range of variations in the release operation time and improve the feeling during auto-release.

Further, in the disc brake 1A according to the first embodiment, it is necessary to consider slipping under no load at the engaging portions between the annular grooves 83 of the shaft member 75 and the annular ridges 110 of the planetary rollers 76. There is no need to provide a pressurization mechanism. Therefore, the tolerance of the axial dimension 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 the manufacturing cost of the planetary roller 76 can be reduced. can.

Next, a disc brake 1B according to a second embodiment will be described in detail with reference to FIGS. 6 to 10. FIG. When describing the disc brake 1B according to the second embodiment, 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 employed in the disc brake 1B according to the second embodiment is composed of a roller screw mechanism 46. As shown in FIG. 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 cylindrical 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 from the small-diameter shaft portion 202 to the other end side, and a large-diameter shaft portion 203 to the other end. and an engaging shaft portion 205 continuously and integrally connected from the intermediate diameter shaft portion 204 to the other end side.

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 the reduction mechanism of the motor gear unit 36 (for example, the carrier of the planetary reduction gear mechanism) so as not to rotate relative to each other. be done. Rotational torque from the motor gear unit 36 is thereby transmitted to the spindle 200 . An annular stepped portion 207 is formed between the outer peripheral surface of the large diameter shaft portion 203 and the outer peripheral surface of the intermediate diameter shaft portion 204 of the spindle 200 . The outer diameter of the engaging shaft portion 205 is smaller than the outer diameter of the intermediate shaft portion 204 . Annular grooves 209 are formed at a predetermined pitch along the axial direction on the outer peripheral surface of the engaging shaft portion 205 . Each annular groove portion 209 is engaged with each annular peak portion 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 inside the cylinder 10 . The thrust bearing 215 has a pair of thrust plates 217, 217 which have axial holes 216, 216 respectively in the center in the radial direction, and a pair of thrust plates 217, 217 arranged along the axial direction. and a plurality of thrust balls 219 that are rotatably arranged between the provided rolling concave surfaces 218 , 218 . The plurality of thrust balls 219 are held by retainers 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 , 216 of the thrust bearing 215 . Thereby, the spindle 200 is rotatably supported by the bottom portion 13 inside the cylinder 10 via the thrust bearing 215 . A plurality of planetary rollers 76 are arranged at intervals along the circumferential direction on the outer periphery of the engagement shaft portion 205 of the spindle 200 . Annular peaks 110 are formed on the outer peripheral surface of the planetary roller 76 at a predetermined pitch along the axial direction. Each annular mountain portion 110 of the planetary roller 76 is engaged with each annular groove portion 209 provided on the outer peripheral surface of the spindle 200 (engagement shaft portion 205). Thereby, the spindle 200 and each planetary roller 76 are restricted from moving relative to each other in the axial direction. These planetary rollers 76 are held by a roller cage 120 .

9 and 10, the roller cage 120 is rotatable around the engagement shaft 205 of the spindle 200 with respect to the spindle 200, and is axially movably supported together with a nut member 210, which will be described later. 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 . Referring to FIG. 10, one annular end surface of roller cage 120 extends spirally with stepped portion 122 . The spiral lead angle is substantially the same as the lead angle of the other end of the coil spring 128, which will be described later. A stepped portion 122 is formed at the end point of the spirally extending end face of the roller cage 120 . The depth (length in the axial direction) of the stepped portion 122 substantially matches the outer diameter of the coil spring 128, which will be described later. The other end of a coil spring 128, which will be described later, engages with the stepped portion 122. As shown in FIG. Referring also to FIG. 9, an annular recess 123 having a larger diameter than 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 is formed continuously from the annular recess 123 and has a diameter reduced toward one end.

A coil spring 128 is arranged around the intermediate diameter shaft portion 204 of the spindle 200 between the spiral end face of the roller cage 120 and the annular stepped portion 207 of the spindle 200 . The coil spring 128 is configured with a left-handed winding. 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 the 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 small-diameter coil portion 130 has substantially the same inner diameter along the axial direction. The inner diameter of the small diameter coil portion 130 is smaller than the outer diameter of the intermediate diameter 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 gradually increases toward one end.

The other 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 131 of the coil spring 128 are connected to the intermediate diameter 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 come into contact with one spiral end surface of the roller cage 120 . In addition, since the small-diameter coil portion 130 of the coil spring 128 is formed to have a smaller diameter than the outer diameter of the intermediate-diameter shaft portion 204 of the spindle 200, the small-diameter coil portion 130 does not move the small-diameter coil portion 130 after assembly. , a predetermined biasing force is applied toward the intermediate diameter shaft portion 204 of the spindle 200 . Corresponding to this biasing force, the 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 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, almost no frictional resistance is generated 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 large-diameter coil portion 131 has a shorter axial length after assembly than before assembly, the large-diameter coil portion 131 applies an urging force along the axial direction. It is assembled in a state in which it is biased away from the shaft portion 203 along the axial direction.

Referring to FIG. 9, a C-shaped retaining ring 135 is arranged at the other end of an 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 smaller in diameter than the inner diameter of the annular groove 209 of the engaging shaft 205. When the retaining ring 135 is attached to the annular groove 209 of the engaging shaft 205, , is attached in a state in which a biasing force is applied toward the annular groove portion 209 . When the roller cage 120 is arranged around the engaging shaft portion 205 of the spindle 200 , the retaining ring 135 is brought 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 toward the other end of the spindle 200 , but the retaining ring 135 restricts axial movement of the roller cage 120 with respect to the spindle 200 . As a result, the roller housing holes 121 of the roller cage 120 and the planetary rollers 76 do not contact each other in the axial direction.

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

Next, the operation of the parking brake that maintains the stopped state of the vehicle by the disk brake 1B according to the second embodiment will be described.
When the electronic control unit 38 receives an apply command (parking brake activation command) by operating the parking switch 39 or the like from the parking brake released state, the electric motor 35 of the motor gear unit 36 is energized to rotate the spindle 200 in the apply direction. Let The rotational torque transmitted to the spindle 200 is transmitted to the planetary roller 76 via the engagement portions between the annular groove portions 209 of the engagement shaft portion 205 of the spindle 200 and the annular peak portions 110 of the planetary roller 76. be. The rotational torque transmitted to the planetary roller 76 is transmitted to the nut member 210 via the engagement portion (meshing portion) between each annular peak portion 110 of the planetary roller 76 and the female thread portion 230 of the nut member 210 . The nut member 210 is supported so as not to rotate relative to the piston 18 and thus to the cylinder portion 7 by the engagement between the stopper protrusions 225 and the engagement recesses 227 provided on the inner peripheral surface of the piston 18. Further, each planetary roller 76 revolves around the axis of the nut member 210 in the apply direction while rotating around its own rotation axis (the roller cage 120 also rotates together). An axial thrust is generated toward the other end (apply direction) according to the applied rotational torque. The nut member 210 that receives the axial thrust toward the other end moves along the axial direction toward the other end (apply direction) and presses the inclined portion 31 of the bottom portion 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 disk rotor D is pressed by the inner and outer brake pads 2 and 3, and braking force of the vehicle is generated.

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

Subsequently, when the braking force generation region in which the inner and outer brake pads 2 and 3 press the disc rotor D is reached, the reaction force from the pressing force to the disc rotor D by the inner and outer brake pads 2 and 3 (along the axial direction 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 small-diameter coil portion 130 of the coil spring 128 and the spindle 200 are expanded. The frictional force between the intermediate diameter shaft portion 204 of the is reduced. As a result, the spindle 200 and the roller cage 120 are easily rotated relative to each other, in other words, the roller screw mechanism 46 undergoes a planetary deceleration motion, and the screw efficiency becomes as high as 50% or more. The driving force to 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 disk rotor D, and the shaft member 75 tries to rotate in the release direction. At this time, the planetary rollers 76 try to rotate (relatively rotate) with respect to the shaft member 75 with a delay due to the planetary deceleration motion, so that the planetary rollers 76 come into contact with the roller housing holes 121 in the circumferential direction. However, in order for the roller cage 120 to rotate relative to the shaft member 75, it must move toward the other end along the lead angle of the coil spring 128, but the movement is restricted by the retaining ring 135. relative rotation is not possible. In other words, the roller screw mechanism 46 cannot perform a planetary deceleration motion in the release direction, and becomes a screw with a low reverse 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 operation of the parking switch 39, it energizes the electric motor 35 of the motor gear unit 36 to rotate the spindle 200 in the release direction. When the spindle 200 rotates in the release direction, the roller cage 120 cannot move axially, so the spindle 200, the coil spring 128 and the roller cage 120 rotate together in the release direction. Subsequently, the rotational torque transmitted to spindle 200 is transmitted to planetary roller 76 via coil spring 128 and roller cage 120 . The rotational torque transmitted to the planetary rollers 76 is transmitted to the nut member 210 via the engaging portions (meshing portions) between the annular ridges 110 of the planetary rollers 76 and the female threads 230 of the nut member 210. be. The nut member 210 is supported so as not to rotate relative to the piston 18 and thus to the cylinder portion 7 by the engagement between the stopper protrusions 225 and the engagement recesses 227 provided on the inner peripheral surface of the piston 10. In addition, each planetary roller 76 revolves in the release direction about the axis of the nut member 210 while the annular peak portion 110 and the internal thread portion 230 slide (the roller cage 120 also rotates). At the time of release, the roller screw mechanism 46 does not perform a planetary deceleration motion, and each planetary roller 76 rotates integrally with the spindle 200 together with the roller cage 120, thereby acting as a rapid feed screw mechanism with low efficiency. 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 engagement portion 45 with the spindle 48, which was adopted in the disc brake 1A according to the first embodiment. Therefore, the number of parts can be reduced, leading to a reduction in manufacturing cost. During application, the roller screw mechanism 46 with low screw efficiency acts as a fast feed screw mechanism before the inner and outer brake pads 2 and 3 press the disk rotor D, and then the inner and outer brake pads 2 and 3 , 3, the spindle 200 and the roller cage 120 rotate relative to each other, in other words, the roller screw mechanism 46 undergoes a planetary deceleration motion, and the screw efficiency is increased to 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, when the roller screw mechanism 46 is released, similarly, the planetary rollers 76 rotate integrally with the spindle 200 together with the roller cage 120 without planetary decelerating motion, thereby acting as a rapid feed screw mechanism with low efficiency. As a result, the nut member 210 moves in the release direction. As a result, variations in the release operation time are suppressed, and the feeling at the time of automatic release can be improved. In this manner, in the disc brake 1B according to the second embodiment, the roller screw mechanism 46 acts as a fast-feed screw mechanism during applying and releasing. Actuation time and release actuation time can be shortened.

1A, 1B disc brake, 2 inner brake pad (pad), 3 outer brake pad (pad), 4 caliper, 6 caliper main 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 housing 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 across the rotor;
a piston that presses one of the pair of pads against the rotor;
a caliper body having a cylinder in which the piston is slidably fitted;
a motor provided in the caliper body;
a rotation-to-linear motion conversion mechanism provided in the caliper body for converting rotary motion of the motor into linear motion to propel the piston;
The rotation-to-linear motion conversion mechanism is
a tubular member;
a shaft member disposed radially inside the tubular member;
a plurality of rolling elements arranged at intervals in the circumferential direction between the shaft member and the tubular member and engaged with the shaft member and the tubular member;
a roller cage disposed between the shaft member and the cylindrical member, and provided with a plurality of housing holes for housing the rolling elements along the circumferential direction;
It is wound around the outer peripheral surface of the shaft member, one end abuts against the axial end of the roller cage, the other end has a larger diameter than the one end, and the other end has a larger pitch than the one end. a coiled member;
A disc brake comprising: 2. The disc brake according to claim 1, wherein a locking member is provided between the roller cage and the shaft member to restrict relative movement along the axial direction. a pair of pads arranged on both sides of the rotor in the axial direction across the rotor;
a piston that presses one of the pair of pads against the rotor;
a caliper body having a cylinder in which the piston is slidably fitted;
a motor provided in the caliper body;
a rotation-to-linear motion conversion mechanism provided in the caliper body for converting rotary motion of the motor into linear motion to propel the piston;
The rotation-to-linear motion conversion mechanism is
a tubular member;
a shaft member disposed radially inside the tubular member;
a plurality of rolling elements arranged at intervals in the circumferential direction between the shaft member and the tubular member and engaged with the shaft member and the tubular member;
a roller cage disposed between the shaft member and the cylindrical member, and provided with a plurality of housing holes for housing the rolling elements along the circumferential direction;
a clutch member that switches relative rotation or integral rotation between the shaft member and the roller cage according to the rotation direction of the shaft member;
A disc brake comprising: 4. The disc brake according to claim 3, wherein the clutch member is an elastic body that axially biases the roller cage against the shaft member.

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