JP4446834B2 - Electric brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To incorporate a planetary gear reduction mechanism in an electric brake device by reducing the number of parts in simple structure. <P>SOLUTION: In the planetary gear mechanism for reducing the speed of rotation drive force of an electric motor, a planetary gear 10 is engaged between an internal gear 8 and a sun gear 9 driven to rotate coaxially with a rotor 6 of an electric motor, and the planetary gear 10 is installed on a rotation carrier 11. Reduced speed of rotation drive force is transmitted from the rotation carrier 11 to a drive force converting mechanism, and an axial load added from the drive force converting mechanism to the rotation carrier 11 is supported by a lid 4a of a casing 4 via a thrust needle roller bearing 13. The number of parts is thus reduced in simple structure, so that the planetary gear reduction mechanism can be incorporated into the electric brake device. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to an electric brake device that converts a rotational driving force of an electric motor into a linear driving force and presses a brake member against a member to be braked.

  Although many hydraulic brake devices have been adopted as a vehicle brake device, in recent years, with the introduction of advanced brake control such as ABS (Antilock Brake System), these controls can be performed without complicated hydraulic circuits. Electric brake devices that can be designed compactly are drawing attention. The electric brake device operates the electric motor in response to a brake pedal depression signal, etc., and transmits the linear driving force to the linear motion member by a driving force conversion mechanism that converts the rotational driving force of the electric motor into a linear driving force. The brake member is pressed against the member to be braked by the linear motion of the member.

  Usually, an electric brake device is mounted under the spring of a vehicle, and a compact and lightweight design is desired. Therefore, in order to make the electric motor small and have a small capacity, the electric brake device is interposed between the electric motor and the driving force conversion mechanism. Many have a reduction mechanism. Various types of speed reduction mechanisms are employed, and there is a planetary gear speed reduction mechanism that can provide a large speed reduction rate (see, for example, Patent Document 1).

  In addition, the driving force conversion mechanism of the electric brake device often employs a screw mechanism that can be compactly designed. As the screw mechanism, the frictional resistance between the screwed rotating member and the linear motion member is small, and the driving force is reduced. A ball screw mechanism with a low conversion loss is often used (see, for example, Patent Document 2). Some of these driving force conversion mechanisms employ a cam mechanism in which a plurality of rolling elements are arranged between cam surfaces facing each other in the axial direction of a rotating member and a linearly moving member.

JP 2002-48170 A (page 2-5, FIGS. 1 and 4) JP 2002-213505 A (page 2-4, FIG. 1-2)

  The electric brake device employing the planetary gear speed reduction mechanism as the speed reduction mechanism described above needs to devise a support structure for the planetary gear rotation carrier that transmits the reduced rotational driving force to the driving force conversion mechanism. In particular, when the linear motion member of the driving force converting mechanism presses the brake member, the rotating carrier is loaded with a large axial load by the pressing reaction force, and thus a device is required to support the axial load.

  Patent Document 1 describes a first planetary gear that meshes with an internal gear and a sun gear provided on the inner periphery of a rotor of an electric motor, and a second gear that meshes with an external gear of a rotating member of a driving force conversion mechanism. A planetary gear is provided, and a rotating carrier that pivotally supports the pair of planetary gears is supported on the casing by a tapered roller bearing. For this reason, by providing planetary gears at two locations in the casing, etc., the structure is complicated and the number of parts is increased, so that the workability of maintenance such as when replacing a worn brake member is deteriorated. There is a problem that the manufacturing cost is also increased.

  Accordingly, an object of the present invention is to incorporate a planetary gear reduction mechanism in an electric brake device with a simple structure and a reduced number of parts.

  In order to solve the above-described problems, the present invention provides a planetary gear reduction mechanism that reduces the rotational driving force of an electric motor in a casing, and a drive that converts the rotational driving force reduced by the planetary gear reduction mechanism into a linear driving force. An electric brake device that presses a brake member against a member to be braked by a linear motion of a linear motion member to which a linear driving force is transmitted by the driving force conversion mechanism. A planetary gear is meshed between an internal gear and a sun gear that are rotationally driven coaxially with the rotor of the electric motor, and the planetary gear is attached to the rotary carrier. Is transmitted to the driving force converting mechanism, and an axial load applied to the rotating carrier from the driving force converting mechanism is supported on the casing by a thrust bearing.

  That is, the planetary gear reduction mechanism is configured such that the planetary gear is meshed between the internal gear and the sun gear that are driven to rotate coaxially with the rotor of the electric motor, and the planetary gear is attached to the rotary carrier. By transmitting the rotational drive force decelerated from the drive force to the drive force conversion mechanism and supporting the axial load applied to the rotary carrier from the drive force conversion mechanism on the casing by the thrust bearing, the number of parts can be reduced with a simple structure. Thus, the planetary gear speed reduction mechanism can be incorporated into the electric brake device.

  By supporting the rotating carrier rotatably on the rotor of the electric motor with a bearing, the axis of the internal gear driven to rotate coaxially with the rotor and the axis of the rotating carrier can be easily held coaxially. can do.

  By using a needle roller bearing as the bearing for supporting the rotating carrier on the rotor, the radial bearing thickness can be designed to be compact.

  By providing a thrust bearing that supports the axial load applied to the rotating carrier on the outer diameter side of the pitch circle diameter of the planetary gear, the load capacity of the axial load can be increased.

  By using a thrust needle roller bearing as the thrust bearing, the axial bearing thickness can be designed to be compact.

  When the thrust needle roller bearing is a double-row thrust needle roller bearing, the load capacity of the axial load can be increased and the rotational resistance can be reduced.

  By making the rotating carrier cylindrical and the driving force conversion mechanism a ball screw mechanism provided on the inner diameter side of the cylindrical rotating carrier, the electric brake device can be designed more compactly and the driving force conversion can be achieved. Conversion loss of driving force in the mechanism can be reduced.

  A linear motion one-way clutch is provided, which allows the linear motion of the linear motion member in the forward direction to press the brake member, but prevents it in the backward direction, and rotates the linear motion one-way clutch toward the linear motion member. It is possible to attach and engage with the inner diameter surface of the rotating carrier, so that even if the brake member is worn, the linear motion member after braking is always near the pressing position of the brake member even if the brake member is worn. The brake member wear compensation mechanism can be incorporated at a low cost without impairing the compact and lightweight design.

  In the electric brake device of the present invention, the planetary gear speed reduction mechanism is engaged with the planetary gear between the internal gear and the sun gear that are driven to rotate coaxially with the rotor of the electric motor, and the planetary gear is attached to the rotating carrier. As a result, the rotational driving force decelerated from the rotating carrier is transmitted to the driving force converting mechanism, and the axial load applied to the rotating carrier from the driving force converting mechanism is supported on the casing by the thrust bearing. The planetary gear speed reduction mechanism can be incorporated into the electric brake device with a simple structure and a reduced number of parts.

  By supporting the rotary carrier on the rotor of the electric motor with a bearing so as to be rotatable, the axis of the internal gear driven to rotate coaxially with the rotor and the axis of the rotary carrier are easily held coaxially. be able to.

  By using a needle roller bearing as the bearing for supporting the rotating carrier on the rotor, the radial bearing thickness can be designed to be compact.

  By providing a thrust bearing that supports the axial load applied to the rotating carrier on the outer diameter side of the pitch circle diameter of the planetary gear, the load capacity of the axial load can be increased.

  By using a thrust needle roller bearing as the thrust bearing, the axial bearing thickness can be designed to be compact.

  When the thrust needle roller bearing is a double-row thrust needle roller bearing, the load capacity of the axial load can be increased and the rotational resistance can be reduced.

  By making the rotating carrier cylindrical and the driving force converting mechanism a ball screw mechanism provided on the inner diameter side of the cylindrical rotating carrier, the electric brake device can be designed more compactly, and the driving force converting mechanism The conversion loss of the driving force can be reduced.

  A linear motion one-way clutch that allows the linear motion of the linear motion member in the forward direction to press the brake member but prevents it in the backward direction is provided so that the linear motion one-way clutch can be rotated to the linear motion member side. By attaching and engaging with the inner diameter surface of the rotating carrier, it is possible to always keep the linear motion member after braking near the pressing position of the brake member even if the brake member is worn by adding a small number of parts. Therefore, the wear compensation mechanism for the brake member can be incorporated at a low cost without impairing the compact and lightweight design.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, this electric brake device is a disc brake in which brake pads 3 as brake members are arranged oppositely on both sides of a disc rotor 2 as a braked member inside a caliper 1. A stator 5 of an electric motor is fixed to an inner diameter surface of a casing 4 formed integrally with the caliper 1 and provided with a lid 4 a on the rear end side, and a rotor 6 is rotatably supported by a bearing 7.

  As shown in FIGS. 1 and 2, an internal gear 8 is coaxially bolted to the axially rear end side of the rotor 6, and between the sun gear 9 bolted to the center of the inner surface of the lid 4a, Four planetary gears 10 meshing with the internal gear 8 and the sun gear 9 are attached to a cylindrical rotary carrier 11 to constitute a planetary gear reduction mechanism. The rotating carrier 11 includes a carrier body 11a rotatably supported on the inner diameter surface of the rotor 6 by a needle roller bearing 12, and a carrier body 11b supported on the inner surface side of the lid 4a by a double-row thrust needle roller bearing 13. Each planetary gear 10 is pivotally supported between a carrier body 11a and a carrier split 11b. The thrust needle roller bearing 13 is provided on the outer diameter side of the pitch circle diameter of the planetary gear 10. The thrust needle roller bearing 13 may be a single row. Further, the carrier body 11a and the carrier body 11b may be formed integrally.

  As shown in FIG. 1, a nut 14 of a ball screw mechanism as a driving force conversion mechanism is fitted into the front end side of the carrier body 11a, and a screw shaft 15 as a linear motion member is inserted through a ball 16 into the nut. 14, and a separate pressing member 17 that presses the brake pad 3 against the disc rotor 2 is bolted to the front end side of the screw shaft 15, and the screw shaft 15 and the pressing member 17 are rotated by a rotation prevention key 18. It has been stopped. Therefore, when the brake member 3 is pressed by the pressing member 17, a large axial load is applied to the rotating carrier 11 via the screw shaft 15 and the nut 14 due to the pressing reaction force. It is supported by the lid 4 a of the casing 4 through a thrust needle roller bearing 13. The front end side of the casing 4 is sealed with a boot 19 attached between the caliper 1 and the pressing member 17.

  As shown in FIG. 3A, a bolt 20 is screwed to the rear end of the screw shaft 15, and a retaining ring member 21 as a linear motion one-way clutch is attached to a stepped portion 20 a provided on the bolt 20. Is attached. As shown in FIG. 4, the retaining ring member 21 is annular and has a cutting portion 21 a at one place on the circumference. Also, holes 21b are provided on both sides of the cutting portion 21a for hooking a tool claw so as to reduce the diameter and remove it from the inner diameter surface of the carrier body 11a when replacing the brake pad 3 described later.

  As shown in FIGS. 3 (a) and 3 (b), the retaining ring member 21 has an inner diameter edge that is not in contact with the stepped portion 20a of the bolt 20 and is rotatable around the stepped portion 20a, and is bent to the outer periphery. The portion 21c is provided so that the outer diameter edge comes into contact with the inner diameter surface of the carrier body 11a at an inclined angle so as to stretch toward the opposite side of the forward direction of the screw shaft 15. Allow linear motion in the forward direction but prevent it in the backward direction. Note that the inner surface of the carrier body 11a with which the outer diameter edge of the retaining ring member 21 contacts has a surface roughness Ra of 6.3 to ensure adequate frictional resistance with the outer diameter edge of the retaining ring member 21. The rough surface is 50 μm.

  At the time of braking in which the screw shaft 15 moves forward, as shown in FIG. 3A, the retaining ring member 21 follows the carrier body 11a and rotates while contacting the head of the bolt 20 together with the screw shaft 15. Move forward. Further, at the time of releasing the brake when the rotation of the electric motor stops, as shown in FIG. 3B, when the screw shaft 15 is retracted by the play amount of the ball screw, the retaining ring member 21 is screwed along the stepped portion 20a. 15 is moved relative to the rear end side and is locked to the rear end surface of the screw shaft 15 to prevent the screw shaft 15 from further retracting. For this reason, since the screw shaft 15 after braking is allowed to be slightly retracted by the backlash gap in the axial direction of attachment of the retaining ring member 21 corresponding to the length of the stepped portion 20a, the brake at the time of non-braking is performed. There is no dragging of the pad 3.

  As described above, this electric brake device rotates the electric motor in one direction at the time of braking, and only stops the electric motor at the time of releasing the brake, and the engagement of the retaining ring member 21 to the inner diameter surface of the carrier body 11a. The combined position naturally moves forward as the brake pad 3 wears during braking gradually moves forward, and the standby position of the screw shaft 15 after braking moves naturally. FIG. 5 shows a state in which the brake pad 3 is worn, and the screw shaft 15 and the retaining ring member 21 have moved considerably forward due to the accumulation of forward movement little by little.

  Next, a method for replacing the worn brake pad 3 will be described. As shown in FIG. 5, with the screw shaft 15 and the retaining ring member 21 moved considerably forward, as shown in FIG. 6, the cover 4a, the sun gear 9, the carrier split 11b, and each planetary gear from the casing 4 10 is removed, the retaining ring member 21 is reduced in diameter with a tool and removed from the inner diameter surface of the carrier body 11a. Thereafter, the carrier body 11a and the nut 14 are reversely rotated via the needle roller bearing 12 by the reverse rotation of the electric motor, whereby the screw shaft 15 is retracted to the initial position and the brake pad 3 is replaced with a new one.

  In the above-described embodiment, the ball screw mechanism is employed as the driving force conversion mechanism, but a normal screw mechanism such as a trapezoidal screw or a cam mechanism may be employed.

A longitudinal sectional view showing an embodiment of an electric brake device Sectional view along the line II-II in FIG. a and b are cross-sectional views showing enlarged main parts of FIG. The top view which shows the retaining ring member of FIG. 1 is a longitudinal sectional view showing a state where the brake pad of FIG. 1 is worn FIG. 5 is a longitudinal sectional view for explaining a method of replacing the worn brake pad in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Caliper 2 Disc rotor 3 Brake pad 4 Casing 4a Cover 5 Stator 6 Rotor 7 Bearing 8 Internal gear 9 Sun gear 10 Planetary gear 11 Rotating carrier 11a Carrier body 11b Carrier split 12 Needle roller bearing 13 Thrust needle roller bearing 14 Nut 15 Screw shaft 16 Ball 17 Press member 18 Non-rotating key 19 Boot 20 Bolt 20a Stepped portion 21 Retaining ring member 21a Cutting portion 21b Hole 21c Bending portion

Claims (5)

The casing includes a planetary gear reduction mechanism that reduces the rotational driving force of the electric motor and a driving force conversion mechanism that converts the rotational driving force decelerated by the planetary gear reduction mechanism into a linear driving force. In the electric brake device that presses the brake member against the member to be braked by the linear motion of the linear member to which the linear driving force is transmitted, the planetary gear reduction mechanism is coupled to the rotor of the electric motor and is driven to rotate coaxially. The planetary gear is meshed between the internal gear and the sun gear, and the planetary gear is attached to the rotary carrier . the rotational drive power reduced from the rotary carrier is transmitted to the driving force converting mechanism, the axial load applied to the rotary carrier from the driving force converting mechanism, the planetary gear Supported on the casing by a thrust bearing provided on the outer diameter side than the pitch circle diameter, electric brake apparatus, characterized in that the thrust bearing and the thrust needle roller bearing. The electric brake device according to claim 1 , wherein the bearing for supporting the rotating carrier on the rotor is a needle roller bearing. The electric brake device according to claim 1 or 2 , wherein the thrust needle roller bearing is a double-row thrust needle roller bearing. The electric brake device according to any one of claims 1 to 3 , wherein the rotary carrier is cylindrical, and the driving force conversion mechanism is a ball screw mechanism provided on an inner diameter side of the cylindrical rotary carrier. A linear motion one-way clutch is provided that allows the linear motion of the linear motion member in the forward direction to press the brake member but blocks in the backward direction. The linear motion one-way clutch is rotated toward the linear motion member. The electric brake device according to claim 4 , wherein the electric brake device is attached so as to be engaged with an inner diameter surface of the rotary carrier.

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