JP2000110907A - Planetary roller screw and brake device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly perform assembling work even when a nut is a bottomed cylindrical shape by arranging cutouts for allowing the shaft directional passage of a roller at least in the specific number in the part of at least a roller receiving rib of the nut. SOLUTION: A roller receiving rib 124 projecting inward in the radial direction from the inner peripheral surface of the nut main body part 94 is formed on the inside surface of the nut main body part 94. A cutout 128 having a cross-sectional shape of a partial circle is at least by a single piece on the inner peripheral surface of the nut main body part 94 so as to extend in the shaft direction. When assembling a planetary roller screw 74, first of all, after installing a single roller 130 in a retainer 150, the retainer 150 is rotated by an angle equal to an angle between adjacent support holes to adjust a support hole adjacent to a support hole for installing the roller 130 to the cutout 128. The next roller 130 is installed in the retainer 150 in the cutout 128 similarly to the first roller 130. The planetary roller screw 74 can be assembled by this repetition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a planetary roller screw,
And a brake device provided with the same.

[0002]

2. Description of the Related Art A planetary roller screw has a plurality of planetary rollers disposed between a nut and a screw shaft. The planetary roller is provided with a thread groove or an annular groove on the outer peripheral surface, and engages with the thread formed on the outer peripheral surface of the screw shaft by the thread groove or the annular groove, while revolving with rotation by a nut. And it is held immovable in the axial direction. One type of this planetary roller is described in JP-A-8-338461. This planetary roller screw is provided with a plurality of roller receiving ribs that protrude radially inward from the inner peripheral surface of a hole having a circular cross-sectional shape and have at least one of both side surfaces as a roller receiving surface. A plurality of rollers each having an inclined tapered surface corresponding to the roller receiving surface, and having a thread groove or an annular groove on each outer peripheral surface, and the plurality of rollers, at both ends of the rollers,
A pair of retainers that are rotatable about the axes of the rollers and that the rollers are held at an equal distance from the center line of the hole; And a screw shaft engaged with the screw groove or the annular groove of the plurality of rollers.

[0003] The assembly of the planetary roller screw is performed as follows. After arranging all the rollers in the nut in a state where the rollers are engaged with the plurality of roller receiving ribs, each of the pair of retainers is inserted into the nut from the opening on both sides of the nut, and each end of each of the plurality of rollers is inserted into the nut. Install the retainer. As a result, the plurality of rollers are restrained in a state where their rotation axes are located on one cylinder concentric with the nut, and the relative position in the axial direction with respect to the nut is defined. It becomes possible. When the screw shaft is screwed into the plurality of rollers, the thread of the screw shaft engages with the screw groove or the annular groove of the plurality of rollers. Originally, a thread groove corresponding to the thread of the screw shaft should be formed on the outer peripheral surface of each roller, but the roller and the screw shaft only engage with each other at a very small part of the outer peripheral part of each other. Therefore, an annular groove may be formed instead of the screw groove.

As described above, the nut of the planetary roller screw needs to be able to insert one retainer from each of the openings on both sides of the nut for the purpose of assembling the pair of retainers. May be difficult to meet, or the overall structure of the device, including the planetary roller screws, may be complicated to meet this condition. For example, the above publication discloses that a planetary roller screw is used as a motion conversion mechanism that converts a rotary motion into a linear motion in an electric brake device, but a retainer is inserted through openings on both sides of a nut. The structure of the entire brake device is complicated due to the necessity of obtaining the structure. If the nut can be made cylindrical with a bottom, the structure of the entire device can be simplified as in a brake device to be described later as an embodiment of the present invention. Was impossible. A similar problem is that although both sides of the nut are open,
For example, because a long cylindrical portion is integrally formed at one end, it also occurs when it is difficult to insert the retainer from the opening on that side and assemble it with the roller.

[0005]

SUMMARY OF THE INVENTION As described above, the present invention relates to a conventional planetary roller which cannot be assembled unless a pair of retainers are inserted from openings on both sides of a nut. It was made to solve the problem of screws. According to the present invention, a planetary roller screw of the following aspects and a brake device including the same are obtained. As in the case of the claims, each aspect is divided into sections, each section is numbered, and if necessary, the other sections are cited in a form in which the numbers are cited. This is to illustrate the technical features described herein and combinations thereof,
The technical features and combinations thereof described herein should not be construed as limited to the following. (1) a nut having at least one roller receiving rib protruding radially inward from an inner peripheral surface of a hole having a circular cross-sectional shape and having at least one of both side surfaces being a roller receiving surface having a tapered surface; A plurality of rollers each having an inclined tapered surface corresponding to the roller receiving surface, and having a thread groove or an annular groove on each outer peripheral surface, and the plurality of rollers, at both end portions of the rollers, the rollers A pair of retainers that are rotatable about the axis of the roller and that the axes of the rollers are held at the same distance from the center line of the hole, and a pair of retainers are provided on the outer peripheral surface. A planetary roller screw including a screw shaft engaging with the screw groove or the annular groove of a plurality of rollers,
At least a portion of the roller receiving rib of the nut,
A planetary roller screw (1), wherein at least one notch is provided to allow the roller to pass in the axial direction. The roller receiving ribs prevent the roller from moving in the axial direction while allowing the rotation of the roller with its rotation.
A pair of rollers each receiving a pair of tapered surfaces formed at both ends of the roller may be provided, and a pair of the grooves may be engaged with one engagement groove formed at an axially intermediate portion of the outer peripheral surface of the roller.
It is also possible to provide one. However, generally, in order to increase the load capacity of the nut, three or more roller receiving ribs are provided at a distance in a direction parallel to the center line of the nut. Each of the plurality of rollers is provided with at least one engagement groove at an intermediate portion in the axial direction, in addition to the tapered surfaces at both ends which engage with the roller receiving ribs at both ends. As for the roller receiving ribs at both ends, one side surface (inner side surface) may be used as the roller receiving surface, but it is preferable that the roller receiving rib at the intermediate portion has both side surfaces serving as the roller receiving surface. When a plurality of roller receiving ribs are provided, the cutouts of the plurality of roller receiving ribs are provided along a straight line parallel to the center line of the nut. When assembling the planetary roller screw, first, one of the pair of retainers is set in the nut from one opening of the nut, and one roller is assembled to the retainer by passing through the notch. For example, the shaft of the roller is fitted into the support hole of the retainer. For this purpose, the roller is provided with a shaft protruding coaxially from the end face, and the retainer is provided with a support hole in which the shaft can be fitted. Conversely, the retainer has a support shaft,
The roller may be fitted in a bearing hole formed in the end face of the roller. In any case, after one roller is assembled to the retainer, the retainer and the roller are rotated by an arrangement pitch of the support holes, the support shafts, and the like, and the support holes, the support shafts, and the like to which the next roller is to be assembled are rotated. The state matches the notch. This allows the next roller to pass through the notch and be assembled to the retainer,
The previously assembled roller is prevented from being detached from the support hole, the support shaft, or the like by the roller receiving rib.
After the predetermined number of rollers have been assembled, a retainer different from the retainer is inserted into the nut through the opening of the nut, and the pair of retainers are in a state where both ends of the plurality of rollers are rotatably held. The pair of retainers and the rollers are prevented from being separated from each other by appropriate means. Finally, the screw shaft is moved in the axial direction while being rotated, and the threads of the screw shaft are engaged with the screw grooves or annular grooves of the plurality of rollers. As described above, since a pair of retainers can be inserted from the same opening of the nut to assemble the planetary roller screw, when the nut has a cylindrical shape with a bottom, or a long cylindrical shape at one end of the nut. Even when the parts are formed integrally, the assembling work can be performed without any trouble. (2) The notch is formed so as to extend from the roller receiving rib to the inside of the nut beyond the inner peripheral surface of the nut.
The planetary roller screw according to (1). The notch may be formed at least in the portion of the roller receiving rib, but if the notch is formed so as to extend beyond the inner peripheral surface to the inside of the nut, the gap between the inner surface of the notch and the outer peripheral surface of the roller is large. As a result, the degree of freedom of the movement of the rollers during the assembly work of the planetary roller screw is increased, and the assembly work is facilitated. (3) The notch has a shape defined by a partial cylindrical surface centered on the axis of the roller in a state where the roller is held by the retainer and incorporated in the nut. (1) or (2) ).
As described above, from the viewpoint of ease of assembly work, it is desirable that the gap between the inner side surface of the notch and the outer peripheral surface of the roller is large, but the roller receiving rib receives the roller at the portion where the notch is formed. The notch should be as small as possible. The notch of this embodiment is particularly excellent in meeting these conflicting requirements. (4) a nut having at least one roller receiving rib protruding radially inward from the inner peripheral surface of the hole having a circular cross-sectional shape and having at least one of both side surfaces being a roller receiving surface. A plurality of rollers each having an inclined tapered surface corresponding to the roller receiving surface, and having a thread groove or an annular groove on each outer peripheral surface, and the plurality of rollers, at both end portions of the rollers, the rollers A pair of retainers that are rotatable about the axis of the roller and that the axes of the rollers are held at the same distance from the center line of the hole, and a pair of retainers are provided on the outer peripheral surface. A planetary roller screw including a screw shaft engaging with the screw groove or the annular groove of a plurality of rollers,
A shaft portion extends concentrically from at least one end of the plurality of rollers, and extends in at least one of the pair of retainers in a radial direction of the retainer, and the shaft portion and movement of the shaft portion in a retainer radial direction. A planetary roller screw (claim 2), characterized in that a longitudinally engaging recess is formed which engages in a state that allows the retainer to be prevented from moving in the circumferential direction of the retainer. The longitudinal engagement recess may be formed so as to penetrate in the thickness direction of the retainer, or may be formed so as not to penetrate. In any case, if at least one of the pair of retainers has a long engaging recess, the retainer is first inserted into the nut, and each of the shafts of the plurality of rollers is inserted into the notch of the retainer. It is possible to engage. When the end of the engagement concave portion on the inner peripheral side of the retainer is determined to be engaged with the shaft portion of the roller in the assembly completed state, and is determined to be a position for preventing the movement of the roller to the inner peripheral side of the retainer, If the roller remains in a position parallel to the center line of the nut, the large-diameter portion of the roller and the roller receiving rib interfere as described above, so the shaft cannot be engaged with the engaging recess of the retainer. As described in detail in the embodiment section, the roller is tilted so that the end opposite to the side on which the shaft portion to be engaged with the engagement recess of the retainer is located on the center line side of the nut. With this arrangement, the shaft portion can be engaged with the engagement concave portion while avoiding interference between the large diameter portion of the roller and the roller receiving rib. Then, if the roller is in a posture parallel to the center line of the nut after the engagement of the two, the large-diameter portion of the roller and the roller receiving rib are engaged, and the roller moves in the axial direction and moves toward the outer periphery of the nut. Is prevented. After assembling all the rollers, if another retainer is assembled to the opposite end of the rollers, the assembly of the rollers and the retainer to the nut is completed. The engaging portion between the another retainer and the roller may be formed as the above-mentioned longitudinally-shaped engaging concave portion. However, a circular support hole that can be fitted to the shaft portion of the roller, or a bearing hole of the roller may be fitted. A support shaft that can be used may be used. Further, in the case where the end of the longitudinally-shaped engaging concave portion of the retainer inserted first, on the inner peripheral side of the retainer, is determined at a position on the inner peripheral side of the retainer further than the position of the shaft portion of the roller in the completed assembly state. While maintaining the roller parallel to the center line of the nut, avoid the interference between the large-diameter portion of the roller and the roller receiving rib of the nut, and place the shaft portion on the inner circumferential side of the retainer of the longitudinal engagement recess. Can be engaged. In this case, the roller can be moved to the retainer inner peripheral side even in a state where the roller is assembled to the retainer, but if the screw shaft is screwed inside the plurality of rollers later, the movement is prevented. There is no problem. (5) The end on the inner peripheral side of the retainer of the elongated engaging recess is determined to be at a position where it engages with the shaft of the roller in the completed assembly state and prevents the roller from moving toward the inner peripheral side of the retainer. The planetary roller according to (4). (6) The planetary roller according to the above mode (4) or (5), wherein the long engaging recess is a cutout extending from the outer peripheral surface to the inner peripheral surface of the retainer. (7) The planetary roller according to (6), wherein the notch is a U-shaped notch, and the shaft is supported at the bottom of the U-shape. (8) The planetary roller according to the above mode (4) or (5), wherein the engagement recess having the elongated shape is a long hole elongated in a retainer radial direction. (9) The planetary roller according to any one of the above modes (4) to (8), wherein the longitudinally engaging recess is formed to penetrate the retainer in the axial direction. (10) The planet according to any one of (1) to (9), wherein the hole of the nut is a bottomed hole, and the retainer is disposed so as to face a bottom surface of the bottomed hole. Roller screw (Claim 3). If the hole of the nut is open at both ends, as described above, after placing all the rollers in the nut, it is possible to attach a pair of retainers to both ends of the rollers. If the hole is a bottomed hole, such an assembling is impossible, so that the effects of the present invention can be most effectively enjoyed.
However, for example, if the nut is formed integrally with the end of the long tube, the retainer on the long tube side is still desirable to be incorporated into the nut before placing the rollers in the nut, It is desirable to apply the present invention. (11) The planetary roller screw according to (10), wherein the nut has a through hole penetrating the bottom of the bottomed hole, and the screw shaft extends through the through hole. (12) At least one of both side surfaces of the roller receiving rib is inclined in a direction opposite to each other, the thickness of the roller receiving rib becomes smaller toward the distal end, and the roller receiving ribs are mutually aligned with the center line of the nut. A plurality of roller receiving ribs are provided at intervals in a parallel direction, and the side surfaces of the plurality of roller receiving ribs adjacent to each other but facing each other are tapered surfaces inclined in such a direction as to be further away from each other toward the leading end side of the roller receiving ribs, The planetary roller screw according to any one of (1) to (11), wherein the tapered surfaces of the rollers are formed corresponding to the tapered surfaces. (13) Three or more roller receiving ribs are provided,
The roller integrally includes a plurality of large diameter portions sandwiched between adjacent ones of the three or more roller receiving ribs, and the notch is formed along a straight line parallel to a center line of the nut. The planetary roller screw according to any one of (1) to (12). (14) The planetary roller screw according to any one of (1) to (13), and the nut of the planetary roller screw is rotatable around a center line of the nut and in a direction parallel to the center line. A housing that is immovably held, a rotation driving device that rotates the nut with respect to the housing, a relative rotation prevention device that prevents relative rotation of the screw shaft with respect to the housing, A friction member engaged so as to be able to transmit pressure, a brake rotator whose rotation is suppressed by pressing the friction member, and a brake rotator capable of contacting and separating the friction member with a friction surface of the brake rotator A torque receiving member that is immovably supported in the rotational direction of the friction member and receives a co-rotating torque applied to the friction member from the brake rotator (Claim 4). A brake device is a disk brake in which a brake shoe as a friction member is pressed against the inner peripheral surface of a brake drum as a brake rotating body, and a brake pad as a friction member is pressed against a side surface of a brake disk as a brake rotating body. However, other brakes may be used. When the brake device is for a vehicle, it is particularly required that the brake device can generate a large and small braking force. For this purpose, it is desirable to convert the rotational drive torque of the rotary drive into a large frictional member pressing force.However, the planetary roller screw reduces the lead angle of the thread of the screw shaft to reduce the large frictional member pressing force. Suitable to get. (15) The brake device according to the mode (14), wherein the rotary drive device includes an electric motor. (16) The brake rotating body is a brake disk having the friction surfaces on both sides, and two friction members are provided so as to be able to contact and separate from both friction surfaces, and the screw shaft is provided between the two friction members. A reaction part integrally provided with the housing is engaged with one of the friction members, and the housing and the reaction part are parallel to the rotation axis of the disk rotor on the torque receiving member. Movably held in any direction
The brake device according to the above mode (14) or (15). When the brake is a disc brake, it is desirable that two friction members are disposed opposite to the friction surfaces on both sides of the brake disc. Each of these two friction members can be pressed against the brake disk by an actuator having a housing, a rotary drive and a planetary roller screw. However, as in this embodiment, the actuator and the reaction portion are braked. It is also possible to press with a caliper connected by a connecting portion extending beyond the outer periphery of the disk, in which case only one actuator is required and an inexpensive brake device is obtained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment in which the planetary roller screw according to the present invention is applied to an electric disc brake device for a vehicle (hereinafter, simply referred to as a brake device). The brake device includes a disk rotor 12 as a rotating body that rotates with wheels.
Both surfaces of the disk rotor 12 are friction surfaces 14, 16 respectively.
A pair of brake pads 18 and 20 are disposed to face the friction surfaces 14 and 16. Each of the brake pads 18 and 20 includes a friction material 22 that comes into contact with each of the friction surfaces 14 and 16 on the front surface.
Has a structure in which a steel back plate 24 is fixed to the back surface of the.

[0007] The brake device also includes a mounting bracket 30. Mounting bracket 3
Numeral 0 is attached to the non-rotating member in a cantilever manner while straddling the disk rotor 12. The mounting bracket 30 holds the pair of brake pads 18, 20 at the positions sandwiching the disk rotor 12 from both sides.
16 (moving in a direction parallel to the axis of rotation of the disk rotor 12), and the brake pads 18, 20 are generated when the brake pads 18, 20 come into contact with the disk rotor 12. Performs the function of receiving turning torque.

The brake device also includes a caliper 50. The caliper 50 includes a caliper main body 60 in which a pad pressing-related portion 52, a motor mounting portion 54, and a support portion 56 are integrated, and a motor housing 80 described later. Are fixed by fixing means such as bolts. The caliper body 60 further includes a pair of arms (not shown) integrally. Two pins (not shown) extending parallel to the pad moving direction are attached to each of the arms, and these two pins are slidably fitted in the pin holes of the mounting bracket 30 in the pad moving direction. As a result, the caliper main body 60 is held by the mounting bracket 30 so as to be movable in a direction parallel to the rotation axis of the disk rotor 12. The caliper 50 is of a floating type.

The pad pressing related portion 52 includes a pressing portion 64 located behind the inner pad 20 inside the pair of brake pads 18, 20, a reaction portion 66 located behind the outer pad 18, and a disk. A connecting portion 6 that connects the two portions 64 and 66 across the rotor 12
8 are integrated with each other. In the pressing portion 64, a pressing member 70 is provided behind the inner pad 20 so as to be movable in the axial direction. The pressing member 70 is brought into contact with the rear surface of the inner pad 20 at the front surface thereof. Behind the pressing member 70, an electric motor 72 is arranged. The pressing member 70 and the electric motor 72 are arranged coaxially with each other in parallel to the pad moving direction, and are connected to each other by a planetary roller screw 74 as a motion conversion mechanism.

The stator 76 of the electric motor 72 is fixed inside the motor housing 80. In the motor housing 80, a main body 82 having a cylindrical shape whose both ends are generally open, and a closing portion 84 for closing one opening thereof are formed as separate components, and are fixed by fixing means such as bolts. Has a bottomed cylindrical shape.
The motor housing 80 is fixed to the motor mounting portion 54 at an end opposite to the side closed by the closing portion 84 by a fixing means such as a bolt. Stator 76
Has a metal core 86 and a coil 88 wound around the core 86. Further, a permanent magnet 90 is provided so as to face the stator 76 with a slight gap therebetween. The permanent magnet 90 is fixed to a nut 92 of a planetary roller screw 74 housed coaxially with the stator 76 in the motor housing 80, and together with the nut 92, the electric motor 72.
Of the rotor.

The nut 92 has a generally cylindrical bottomed nut body 94 and a cylindrical section 96 having a smaller diameter than the nut body 94 and extending coaxially from the bottom of the nut body 94. Things. The cylindrical portion 96 is rotatably supported by the closing portion 84 of the motor housing 80 via the radial bearing 98, while the nut body 94 is supported by the caliper body 6 via the radial thrust bearing 100.
The nut 92 is rotatably supported by the caliper 50 by being rotatably supported by the support portion 56 of the no.
An annular groove is formed in a portion of the inner peripheral surface of the support portion 56 of the caliper main body portion 60 adjacent to the radial thrust bearing 100 in the axial direction, and a snap ring 102 is mounted. The radial thrust bearing 100 is sandwiched from both sides in the axial direction by the snap ring 102 and the shoulder surface 104 of the support portion 56, and the axial movement of the nut 92 is prevented via the radial thrust bearing 100. Nut 92
A flange 106 is formed between the cylindrical portion 96 and the nut body 94 to protrude radially to a position close to the stator 76. The flange 106 is formed on the outer peripheral surfaces of the flange 106 and the nut body 94. The permanent magnet 90 is sandwiched from both sides in the axial direction and is prevented from moving in the axial direction by the snap ring 108 attached to the ring groove of the annular groove shape. The permanent magnet 90 is also fixed to the nut 9 by a relative rotation preventing member (not shown) provided between the permanent magnet 90 and the nut 92.
Rotation relative to 2 is prevented. As an example of the relative rotation preventing member, there is a key mounted in a key groove of the nut main body 94, and a protrusion of the key from an outer peripheral surface of the nut main body 94 engages with a key groove formed in the permanent magnet 90. Let me do. A pin erected on the nut body 94 may be engaged with a pin hole formed in the permanent magnet 90.

As shown in FIGS. 4 and 5, the center of the bottom surface 112 of the nut body 94 is provided with a through hole 1 in the cylindrical portion 96.
14 is open, and the nut 92 is a stepped cylindrical member having a stepped through hole as a whole. On the inner peripheral surface of the nut body 94, shallow annular grooves 118 are formed at a plurality of locations (four in the present embodiment) that are spaced apart in the axial direction, and a clearance is formed adjacent to the bottom of the nut body 94. The groove 120 has a large-diameter hole 122 formed on the opening side. As a result, between the plurality of annular grooves 118, between the annular groove 118 and the relief groove 120, and between the annular grooves 118.
Roller receiving ribs (hereinafter, abbreviated as ribs) 124 projecting radially inward from the inner peripheral surface of the nut main body portion 94 are formed between the nut and the large-diameter hole 122, respectively. The longitudinal cross-sectional shape of the annular groove 118 is trapezoidal. As a result, the side face of each rib 124 on the annular groove 118 side is a roller receiving surface 1 that is a tapered surface whose diameter increases toward the tip end of the rib 124.
26. As shown in FIG. 5, a notch 128 having a partial cross-sectional shape extending in the axial direction is formed on the inner peripheral surface of the nut main body 94, as shown in FIG. Notch 128
Is formed at a depth that extends from the bottom surface of the annular groove 118 to the inside of the nut body portion 94, and the rib 124 has a partial annular shape excluding the portion where the notch 128 is formed. In the present embodiment, all side surfaces of the plurality of ribs 124 are tapered, but the side surfaces of the ribs 124 at both ends on the side of the annular groove 118 functioning as the roller receiving surface 126 are tapered. As long as it is a face,
The opposite side surface may be a surface perpendicular to the center line of the nut main body portion 94, and at least one of the relief groove 120 and the large-diameter hole 122 is omitted to make the rib wider than the other ribs 124. You may.

A plurality of rollers 130 and a single screw shaft 132 are disposed inside the nut 92, as shown most clearly in FIGS. Screw shaft 132
A thread 134 having a relatively small lead angle is formed on the outer peripheral surface of the. The pressing member 70 is integrally formed at the tip of the screw shaft 132 protruding from the nut 92. The screw shaft 132 is provided between the pressing member 70 and the inner pad 2.
0, a rotation preventing device (not shown) provided between
Rotation around the axis is prevented. As the anti-rotation device, for example, a pin in which a pin fixed at a position eccentric from one axis of the pressing member 70 and the back plate 24 of the inner pad 20 is fitted into a pin hole formed in the other. Can be adopted. 136 is a dust boot.

In the portion corresponding to the plurality of annular grooves 118 of the nut body 94, a plurality of rollers (six in this embodiment) are arranged at equal angular intervals.
Each roller 130 has a shape in which a plurality of (four in the present embodiment) large-diameter portions 138 are integrally joined at their respective adjacent ends, and both sides of the large-diameter portion 138
An engagement groove 140 that forms an inclined taper surface corresponding to the roller receiving surface 126 of No. 4 is formed. The width of the annular groove 118 of the nut body 93 in the axial direction is equal to the large diameter portion 13 of the roller 130.
8 is equal to the length of the roller receiving surface 12 of each rib 124.
6 are adapted to receive each large diameter portion 138 of the rollers 130 at their tapered surfaces. The roller receiving surface 12 of the rib 124 is also provided on both end surfaces of the roller 130 separated in the axial direction.
6, a tapered surface 141 having an inclination corresponding to 6 is formed.
These tapered surfaces 141 are also received by the roller receiving surface 126.

The outer peripheral surface of each large diameter portion 138 has an engaging groove 14
A plurality of annular grooves 142 shallower than 0 are formed adjacent to each other in the axial direction. These annular grooves 142 can be engaged with the threads 134 of the screw shaft 132. Note that, instead of the annular groove 142, a screw groove having a lead angle corresponding to the screw thread 134 can be formed. A shaft portion 144 projects axially from both end surfaces of the roller 130, and the roller 130 is rotatably held by the pair of retainers 150 at the shaft portion 144. Retainer 1
50 has an annular shape smaller in diameter than the inner peripheral surface at the tip of the rib 124, and the inner diameter of the central through hole 152 is larger than the outer diameter of the screw shaft 132. A plurality of support holes 154 are provided at equal intervals in the circumferential direction in the retainer 150 (in the case of this embodiment, 6
The shaft portion 144 of the roller 130 is rotatably fitted in each support hole 154. Thereby,
The plurality of rollers 130 are constrained so that their rotation axes extend parallel to the center line of the nut body 94 at equiangular intervals on one cylindrical surface concentric with the nut body 94. The plurality of tapered surfaces are kept in a state of being received by the plurality of roller receiving surfaces 126. In this state, the outer peripheral surface of the large diameter portion 138 of the roller 130 and the nut 92
A gap is formed between the annular groove 118 and the bottom surface of the annular groove 118. One of the pair of retainers 150 is connected to the nut body 94.
Is prevented from being separated from the shaft portion 144 by the bottom surface 112,
The other is prevented from being detached from the shaft 144 by a snap ring 156 attached to the nut body 94. Further, the rollers 130 prevent the pair of retainers 150 from approaching each other.

As described above, the pair of retainers 150
The inside of the plurality of rollers 130 held in a state in which only revolution with rotation is allowed by the nut body portion 94 and
The screw shaft 132 is screwed into the annular groove 14 of each roller 130.
2 and the thread 134 of the screw shaft 132 are engaged. Therefore, when the nut 92 is rotated by the electric motor 72, the roller 130 rolls on the roller receiving surface 126 of the rib 124 and on the thread 134 of the screw shaft 132, and the screw shaft 132 moves with respect to the nut body 94. Relative movement in the axial direction. For example, if the nut 92 is rotated forward, the screw shaft 132 moves forward (moves to the right in the drawing), and the pressing member 70 presses the inner pad 20 against the disk rotor 12, and the reaction force of the inner pad 20 causes the outer pad 1 to move.
8 is pressed against the disk rotor 12. Nut 92
Is rotated in the reverse direction, the screw shaft 132 retreats (moves to the left in the drawing), and the pressing of the inner pad 20 and the outer pad 18 against the disk rotor 12 is released. The screw shaft 132 is longer than a portion that engages with the plurality of rollers 130, but a portion that is not screwed with the rollers 130 is accommodated in the cylindrical portion 96.

When the planetary roller screw 74 is assembled, first, one of the pair of retainers 150 is inserted from the opening side of the nut body 94 and is supported by the bottom surface 112 and the center of one support hole 154. Line and notch 128
Of the nut in the circumferential direction with respect to the center line of the nut. Thereafter, one roller 130 is inserted from the opening side of the nut main body 94 in a posture parallel to the nut axis direction, and the notch 1
With the shaft 144 positioned in the holder 28, the shaft 144 is fitted into the support hole 154 of the retainer 150. The retainer 150 on which the one roller 130 is mounted is rotated by an angle equal to the angle between the adjacent support holes 154,
A support hole 154 adjacent to the support hole 154 on which the roller 130 is mounted is aligned with the notch 128. Accordingly, the engagement groove 14 of the roller 130 assembled first is
0 engages with the rib 12 of the nut body 94,
0 is prevented from being detached from the retainer 150. Then, the next roller 130 is the first roller 13
In the same manner as in the case of No. 0, it is assembled to the retainer 150 in the notch 128. Hereinafter, the same is repeated, and after the last roller 130 is assembled to the retainer 150,
The other retainer 15 from the opening side of the nut body 94
0 is inserted, and the plurality of support holes 154 thereof and the shaft portions 144 of the plurality of rollers 130 are fitted. Subsequently, the snap ring 156 is attached to a ring groove formed on the inner peripheral surface of the nut main body 94 and is engaged with the outer surface of the retainer 150, so that the retainer 150 is prevented from coming off in the axial direction. Finally, the screw shaft 132 is inserted from the opening side of the nut body 94 and screwed to the plurality of rollers 130. The thread 134 of the screw shaft 132 and the roller 13
The engagement with the 0 annular groove 142 is completed, and the assembly of the planetary roller screw 74 is completed.

In this embodiment, the nut body 94 of the nut 92 has a bottomed cylindrical shape, and a relatively small-diameter cylindrical portion 96 is formed integrally with the bottom. Since the radial bearing 98, which is one of the two bearings for supporting the nut 92, supports the cylindrical portion 96, it can be small. The outer peripheral surface of the cylindrical portion 96 and the motor housing 8
The annular space between the inner peripheral surface of the electric motor 72 and the inner peripheral surface of the electric motor 72 can be effectively used as a housing space for wiring for the electric motor 72 and the like. If a nut in which the cylindrical portion 96 has the same diameter as the nut body portion 94 is used instead of the nut 92, the retainer 150
Can be inserted from the openings on both sides of the nut and assembled, but on the other hand, the above advantages must be abandoned. Since the brake device is disposed in a narrow space within the wheel and is an additional mass of the wheel from the viewpoint of preventing vibration of the vehicle, it is strongly desired to reduce the size and weight. Yes, it is not desirable to give up the above advantages. Therefore, in this embodiment, the nut 92 is formed by forming the notch 128 in the nut body 94.
Is a stepped cylindrical member.

As another embodiment of the present invention, as shown in FIGS. 6 to 8, a retainer 502 having a U-shaped notch 500 can be used instead of the support hole 154. Like the retainer 150, the retainer 502 is formed in an annular shape having a through hole 501 in the center that is larger than the outer diameter of the screw shaft, and a plurality of the U-shaped notches 500 are arranged at equal intervals in the circumferential direction (in the case of the present embodiment). 6) are formed. The notch 500 is formed to extend from the outer peripheral surface of the retainer 502 to the inner peripheral surface side, and is formed so as to penetrate the retainer 502 in the axial direction. The shaft portion 505 of the roller 504 that engages with the notch 500 is allowed to move outward in the radial direction of the retainer 502, but is not allowed to move inward in the radial direction and the circumferential movement of the retainer 502 within the notch 500. Substantially blocked by the sides. 7 and 8, as in the case of the roller 130, illustration of an annular groove or a thread formed on the outer peripheral surface of the large diameter portion 506 is omitted. Nut 508 in this embodiment
Has a plurality of annular roller receiving ribs 510.

When assembling the planetary roller screw configured as described above, first, one of the pair of retainers 502 is inserted into the nut 508 and the bottom surface 512 of the nut 508 is inserted.
7, the roller 504 is inclined so that the end opposite to the insertion tip is located on the center line side of the nut 508 as shown in FIG. In a state where interference with the rib 510 is avoided, the shaft 50
5 is engaged in one of the notches 500. When the roller 504 is rotated to a position parallel to the center line of the nut 508 as shown in FIG. 8 in a state where the base end side of the shaft 505 is supported by the bottom of the notch 500, the tapered surface 514 of the roller 504 is formed. And the engagement groove 516 is engaged with the roller receiving rib 510 of the nut 508, and the large-diameter portion 506 is slightly lifted from the retainer 502. The roller receiving rib 510 prevents the roller 504 from coming off in the axial direction, and prevents the roller 504 from moving toward the outer periphery of the retainer. The roller 50
4 is prevented from moving inward of the retainer by the bottom of the notch 500. Thereafter, after all the rollers are assembled in the same manner, the other end of the retainer (not shown) is attached, and the separation of the roller 504 from the shaft portion 505 is prevented by a snap ring (not shown).
The mounting of the retainer 04 and the retainer 502 to the nut 508 is completed. In the present embodiment, the other retainer also has a U-shaped notch, similarly to the retainer 502 mounted earlier, but the retainer 150
It is also possible to have a circular support hole in the same manner as described above. Then, a screw shaft (not shown) is screwed into the roller 504, and the assembly of the planetary roller screw is completed.

According to the present embodiment, even if the nut 508 is not provided with a notch, the roller 504 is inclined so that interference between the large-diameter portion 506 and the roller receiving rib 510 can be avoided, and the retainer 502 and the nut 508 can be provided. Can be assembled. The roller 504 is formed by the U-shaped notch 500.
This is because the inclination of the shaft portion 505 is allowed. The notch 500 in the present embodiment is an example of a long engaging recess.

As another form of the long engaging recess, an elongated hole 600 can be employed as shown in FIG. The long hole 600 is long in the radial direction of the retainer 602,
Like the notch 500, the shaft portion 605 of the roller 604 is allowed to move in the retainer radial direction, and is substantially prevented from moving in the retainer circumferential direction. The elongated hole 600 is formed so as not to penetrate the retainer 602 in the axial direction. This is to avoid insufficient strength of the retainer 602 due to the formation of the elongated hole 600. The retainer 602 has a plurality of elongated holes 600 formed at equal intervals in the circumferential direction. In FIG. 9, illustration of an annular groove or a screw groove formed on the outer peripheral surface of the large diameter portion 606 of the roller 604 is omitted. Further, an annular fitting portion 612 having a slightly smaller inner diameter than the annular roller receiving rib 610 is formed at a portion adjacent to the bottom surface 609 of the nut 608 in the present embodiment,
A retainer 602 is fitted inside.

When assembling the planetary roller screw in this embodiment, first, one of the retainers 602 is
And supported by the bottom surface 609. The roller 604 is inserted into the nut 608 at a position where the center line of the roller 604 is parallel to the center line of the nut 608 and the large-diameter portion 606 of the roller 604 does not interfere with the roller receiving rib 610. The part 605 is engaged with the slot 600. The length of the elongated hole 600 is set to a length that allows the engagement of the shaft portion 605 even in such a state. Subsequently, the shaft portion 605 is
The roller 604 is moved radially outward while being guided to zero, and the engagement groove 614 and the tapered surface 616 of the roller 604 are engaged with the respective roller receiving ribs 610 to complete the assembly of one roller 604. . In this state, a slight gap is formed between the shaft portion 605 of the roller 604 and the outer end of the elongated hole 600 of the retainer 602.
After all the rollers 604 are assembled, if a screw shaft (not shown) is screwed into each roller 604, the rollers 604
Is in a state where it is prevented from moving toward the inner peripheral side of the retainer by engagement with the screw shaft. The roller 604 is provided with the roller receiving rib 6.
The engagement with the shaft 10 prevents the shaft from slipping out in the axial direction and also prevents the retainer from moving toward the outer periphery. Also in the present embodiment, the roller 604 can be assembled to the nut 608 and the retainer 602 without interfering with the roller receiving rib 610 without providing a cutout in the nut. It can be easily assembled while maintaining a posture parallel to.

In this embodiment, the nut 60
8, the retainer 602 is provided.
Is kept coaxial with the nut 608, but if the shaft 605 and the end on the outer peripheral side of the elongated hole 600 are engaged in a state where the roller 604 is assembled to the nut 608, Even if the fitting part 612 is omitted, the retainer 60
The coaxiality with the second nut 608 can be maintained. Further, in the embodiment shown in FIG. 1 to FIG. 5 or the embodiment shown in FIG. 6 to FIG. 8, it is possible to form a fitting part similar to the fitting part 612 so that during the assembly operation, Can prevent the retainer from moving in the radial direction.

Although the embodiments of the present invention have been described in detail, these are merely examples, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. .

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a brake device according to an embodiment of the present invention.

FIG. 2 is a front sectional view showing a planetary roller screw of the brake device.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a front sectional view showing a nut which is a component of the planetary roller screw.

FIG. 5 is a side view of a nut which is a component of the planetary roller screw.

FIG. 6 is a side view showing a retainer which is a component of a planetary roller screw according to another embodiment of the present invention.

FIG. 7 is a view for explaining an assembled state of the planetary roller screw.

FIG. 8 is a view for explaining another state of assembling the planetary roller screw.

FIG. 9 is a front (partially sectional) view showing a part of a planetary roller screw according to still another embodiment of the present invention.

[Explanation of symbols]

12: Disc rotor 18:20: Brake pad 30: Mounting bracket 50: Caliper 72: Electric motor 74: Planetary roller screw
92: Nut 94: Nut main body 96: Cylindrical part 112: Bottom 118: Annular groove 124: Roller receiving rib (rib)
126: roller receiving surface 128: notch 130: roller 132: screw shaft
134: thread 140: engagement groove 141: tapered surface 142: annular groove 144: shaft 150: retainer 152: through hole 154: support hole 156: snap ring 500: notch 5
02: Retainer 504: Roller 505: Shaft
508: Nut 510: Roller receiving rib 51
4: Tapered surface 516: Engagement groove 600: Slot 602: Retainer 604: Roller 605: Shaft 608: Nut 610: Roller receiving rib 612: Fitting portion 614: Engagement groove 616: Tapered surface

Claims (4)

[Claims] 1. A nut having at least one roller receiving rib protruding radially inward from an inner peripheral surface of a hole having a circular cross section and having at least one of both side surfaces being a tapered surface. A plurality of rollers each having an inclined tapered surface corresponding to the roller receiving surface, and having a thread groove or an annular groove on each outer peripheral surface, and the plurality of rollers, at both ends of the rollers, A pair of retainers that are rotatable about the axes of the rollers and that the axes of the rollers are held at an equal distance from the center line of the hole; A planetary roller screw including a screw shaft engaged with the screw groove or the annular groove of the plurality of rollers, wherein at least a portion of the roller receiving rib of the nut,
A planetary roller screw comprising at least one notch that allows the roller to pass in the axial direction. 2. A nut having at least one roller receiving rib protruding radially inward from an inner peripheral surface of a hole having a circular cross-sectional shape and having at least one of both side surfaces as a roller receiving surface. A plurality of rollers each having an inclined tapered surface corresponding to the roller receiving surface, and having a thread groove or an annular groove on each outer peripheral surface, and the plurality of rollers, at both ends of the rollers, A pair of retainers that are rotatable about the axes of the rollers and that the axes of the rollers are held at an equal distance from the center line of the hole; A planetary roller screw including a screw shaft engaged with the screw groove or the annular groove of the plurality of rollers, wherein a shaft portion extends concentrically from at least one end of the plurality of rollers. And engages with at least one of the pair of retainers in a state in which the retainer extends in the radial direction of the retainer, and the shaft and the retainer are allowed to move in the retainer radial direction, but are prevented from moving in the retainer circumferential direction. A planetary roller screw, wherein a long engaging recess is formed. 3. The planetary roller screw according to claim 1, wherein the hole of the nut is a bottomed hole, and the retainer is disposed so as to face a bottom surface of the bottomed hole. 4. The planetary roller screw according to claim 1, wherein the nut of the planetary roller screw is rotatable around a center line of the nut and is not movable in a direction parallel to the center line. A rotation driving device for rotating the nut with respect to the housing; a relative rotation preventing device for preventing relative rotation of the screw shaft with respect to the housing; and at least a pressing force transmission with an end of the screw shaft. A friction member that engages with the brake member, a brake rotator whose rotation is suppressed by pressing the friction member, and a rotation of the brake rotator that can contact and separate the friction member from a friction surface of the brake rotator. A torque receiving member that is immovably supported in the direction and receives a co-rotating torque applied to the friction member from the brake rotator.