JP2006038171A - Motor driven brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor driven brake device adopting a cam mechanism for a driving force converting mechanism and incorporating a parking brake operating mechanism in a compact fashion. <P>SOLUTION: On the axial front face side of a cylindrical rotating member 8 to which the rotation driving force of an electric motor 5 is transmitted from a speed reduction mechanism, the cam mechanism is provided for converting the rotating motion into linear motion in the axial direction to thrust a brake pad 3 against a disc rotor 2. The whole cam mechanism is movable to the axial direction of the cylindrical rotating member 8. A cylindrical screw member 15 to be threaded to the inner diameter face of the cylindrical rotating member 8 is made to abut on the rear face side of the cam mechanism, and a driving shaft 17 to be rotationally driven by the operation end of a parking brake is inserted into the inner diameter side of the cylindrical screw member 15 so that its rotation is transmitted via a one-way clutch 19 to the cylindrical screw member 15. Thus, the cylindrical screw member 15 is driven forward in the axial direction to thrust the brake pad 3 against the disc rotor 2 via the whole cam mechanism movable to the axial direction. <P>COPYRIGHT: (C)2006,JPO&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 by a screw mechanism and presses a brake member against a member to be braked, and in particular, an electric brake incorporating a parking brake operating mechanism. Relates to the device.

  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. An electric brake device operates an electric motor in response to a brake pedal depression signal, etc., converts the rotational driving force of the electric motor into a linear driving force, and presses the brake member against the member to be braked with this linear driving force. is there.

  As a driving force conversion mechanism that converts the rotational driving force of the electric motor into a linear driving force, a screw mechanism in which a nut and a screw shaft are screwed together is often employed, and recently, cams of two cam members that face each other in the axial direction. There is also proposed a cam mechanism in which a plurality of rolling elements that engage with these cam surfaces are arranged between the surfaces (see, for example, Patent Document 1).

  For such an electric brake device, there is a demand for a compactly integrated parking brake operating mechanism that also serves as a backup function when electrical control becomes impossible. Several electric brake devices incorporating a parking brake operating mechanism have been proposed in which a screw mechanism is used as the driving force conversion mechanism (see, for example, Patent Document 2), but a cam mechanism is used as the driving force conversion mechanism. The one adopted has not been developed yet.

Japanese Unexamined Patent Publication No. 2003-156086 (page 3-5, FIG. 1-3) Utility Model Registration Gazette No. 2546348 (page 2-4, Fig. 1)

  Therefore, an object of the present invention is to incorporate a parking brake operating mechanism in a compact manner into an electric brake device employing a cam mechanism as a driving force conversion mechanism.

  In order to solve the above problems, the present invention converts the rotational driving force of an electric motor into a linear driving force, presses the brake member against the member to be braked with this linear driving force, and drives it by the operation end of the parking brake. In the electric brake device incorporating a parking brake operating mechanism that converts the rotational driving force of the driven shaft into a linear driving force and also presses the brake member against the braked member by this linear driving force. A configuration is adopted in which the rotational driving force is converted into a linear driving force by a cam mechanism, the rotational driving force of the drive shaft is converted into a linear driving force by a screw mechanism, and the conversion to the linear driving force is performed on the same axis.

  That is, the rotational driving force of the electric motor is converted into a linear driving force by a cam mechanism, the rotational driving force of the drive shaft is converted into a linear driving force by a screw mechanism, and the conversion to the linear driving force is performed on the same axis. As a result, the parking brake operating mechanism can be incorporated in a compact manner into an electric brake device that employs a cam mechanism as the driving force conversion mechanism.

  A means for pressing the brake member against the member to be braked by coaxially converting to a linear driving force by the cam mechanism and the screw mechanism is provided with a cylindrical rotating member that transmits the rotational driving force of the electric motor. And a cam mechanism for converting the rotational motion into a linear motion in the axial direction and pressing the brake member against the member to be braked on the same axis on the axial front side of the cylindrical rotating member. Can be moved in the axial direction of the cylindrical rotating member, and a cylindrical screw member provided on the outer diameter surface with a male screw that engages with an internal screw provided on the inner diameter surface of the cylindrical rotating member is applied to the rear surface side of the cam mechanism. The drive shaft is coaxially inserted into the cylindrical screw member from the axial rear side of the cylindrical rotating member on the inner diameter side of the cylindrical screw member, and the cylindrical screw member is rotated via a one-way clutch. The cylindrical screw member on one side Provided with a screw mechanism that is driven forward in the axial direction by the rotation transmitted to the shaft, and the brake member is braked through the entire cam mechanism that is movable in the axial direction by the forward drive of the cylindrical screw member by the screw mechanism. When the brake member is worn by being pressed against the member, the pressed position gradually changes so as to move forward. With this change in the pressed position, the cylindrical screw member that is driven forward is used. The position of the entire cam mechanism to be pressed is also changed forward, and the standby position is held near the pressing position of the brake member, so that excellent responsiveness of the brake effect can be naturally secured.

  The cam mechanism includes a first cam member that rotates together with the cylindrical rotary member on the inner diameter side of the cylindrical rotary member, is movable in the axial direction, and has a first cam surface on the front side, and the first cam. A second cam member disposed on the front side of the member so as to be axially movable and provided with a second cam surface facing the first cam surface on the rear side; the first cam surface and the second cam; A plurality of rolling elements that engage with these cam surfaces and convert the rotational motion of the first cam member into linear motion in the axial direction of the second cam member may be employed. it can.

  By using tapered rollers for the rolling elements, it is possible to ensure a load capacity for a large linear driving force and to eliminate relative slip between the rolling elements and the cam surface.

  The male screw of the cylindrical screw member is a serrated screw having a flank angle on the front surface of the screw thread facing the front side of the cylindrical screw member that is smaller than the flank angle on the rear surface of the screw thread. By rotating in the direction, the cylindrical screw member can be smoothly driven forward in the axial direction.

  A cylindrical member is fitted to the outer diameter surface of the drive shaft by a spline so as to be movable in the axial direction, and a one-way clutch for transmitting rotation in one direction to the cylindrical screw member is fitted to the cylindrical member. The cylindrical screw member can be driven forward more smoothly in the axial direction.

  Only one of the bearings that support the cylindrical rotating member is to support a radial load and a thrust load, and the remaining other bearings are to support only a radial load, thereby reducing the radial load and the thrust load. The cylindrical rotating member bearing to be loaded can be made of an inexpensive one.

  By transmitting the rotational driving force of the electric motor to the cylindrical rotating member via a speed reduction mechanism, the electric motor can be made small with a small capacity.

  A worm gear can be used as the speed reduction mechanism.

  The electric brake device of the present invention converts the rotational driving force of the electric motor into a linear driving force by the cam mechanism, and converts the rotational driving force of the drive shaft driven by the operation end of the parking brake into the linear driving force by the screw mechanism. Since the conversion into the linear driving force is performed on the same axis, the parking brake operating mechanism can be compactly incorporated into the electric brake device employing the cam mechanism as the driving force converting mechanism.

  Conversion to linear driving force by the cam mechanism and screw mechanism is performed on the same axis, and a means for pressing the brake member against the member to be braked is provided with a cylindrical rotating member that transmits the rotational driving force of the electric motor, A cam mechanism for converting the rotational motion into a linear motion in the axial direction and pressing the brake member against the member to be braked is provided on the same axis on the axial front side of the cylindrical rotating member. The entire cam mechanism is cylindrical. A cylindrical screw member provided on the outer diameter surface with a male screw threadedly engaged with a female screw provided on the inner diameter surface of the cylindrical rotation member is brought into contact with the rear surface side of the cam mechanism so as to be movable in the axial direction of the rotary member. A drive shaft is coaxially inserted into the inner diameter side of the cylindrical screw member from the axial rear surface side of the cylindrical rotary member, and the rotation of the drive shaft is transmitted to the cylindrical screw member via a one-way clutch to form a cylindrical shape. Axial direction with rotation transmitted through screw member in one direction By providing a screw mechanism that drives forward, the brake member is pressed against the member to be braked through the entire cam mechanism that is movable in the axial direction by the forward drive of the cylindrical screw member by this screw mechanism. When the member wears, the pressed position gradually changes so as to move forward. With this change in the pressed position, the position of the entire cam mechanism pressed by the cylindrical screw member that is driven forward also moves forward. It is possible to change and hold the standby position close to the pressing position of the brake member, and naturally ensure excellent braking effectiveness responsiveness.

  When the cam mechanism is to be engaged with a plurality of rolling elements on the cam surface opposed in the axial direction, by using a tapered roller for the rolling element, a load capacity for a large linear driving force can be secured, Relative sliding between the rolling element and the cam surface can be eliminated.

  The male screw of the cylindrical screw member is a serrated screw having a flank angle on the front surface of the screw thread facing the front side of the cylindrical screw member that is smaller than the flank angle on the rear surface of the screw thread. By rotating in the direction, the cylindrical screw member can be smoothly driven forward in the axial direction.

  A cylindrical member is fitted to the outer diameter surface of the drive shaft by a spline so as to be movable in the axial direction, and a one-way clutch that transmits rotation in one direction to the cylindrical screw member is fitted to the cylindrical member. The cylindrical screw member can be driven forward more smoothly in the axial direction.

  Only one of the bearings that support the cylindrical rotating member is to support a radial load and a thrust load, and the remaining other bearings are to support only a radial load, thereby reducing the radial load and the thrust load. The cylindrical rotating member bearing to be loaded can be made of an inexpensive one.

  By transmitting the rotational driving force of the electric motor to the cylindrical rotating member via a speed reduction mechanism, the electric motor can be made small with a small capacity.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 3, 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 the caliper 1. The electric motor 5 is attached to the casing 4 attached to the rear end side of the caliper 1 with the output shaft 5a oriented perpendicular to the pad pressing direction to the disc rotor 2, and the rotational driving force of the electric motor 5 serves as a speed reduction mechanism. The worm 6 and the gear 7 mesh with each other so that the worm 6 and the gear 7 are transmitted to the cylindrical rotating member 8 splined to the inner diameter of the gear 7.

  The cylindrical rotating member 8 has an inner diameter surface of the caliper 1 by a deep groove ball bearing 9a that supports a radial load and a thrust load with an axial direction facing a pad pressing direction and a needle roller bearing 9b that supports only the radial load. A first cam member 10 provided with a first cam surface 10a on the front side is fitted by a spline 8s so as to be movable in the axial direction on the inner diameter surface of the large-diameter portion on the front end side. . A second cam member 11 provided with a second cam surface 11a on the rear side on the front side coaxial with the first cam member 10 is axially connected to a rotation preventing member 12 attached to the inner diameter surface of the caliper 1. It is fitted by a spline 12s so as to be movable to Note that a boot 13 that seals the rear end side of the caliper 1 and the inside of the casing 4 is attached to the second cam member 11.

  As shown in FIGS. 4 (a) and 4 (b), the first cam surface 10a and the second cam surface 11a are provided to be opposed to a plurality of locations in the circumferential direction, and these opposing cam surfaces 10a, A taper roller 14 serving as a plurality of rolling elements that engage with the cam surfaces 10 a and 11 a is disposed between the cam surfaces 10 a, and the rotational movement of the first cam member 10 transmitted from the electric motor 5 is transmitted to the second cam member 11. A cam mechanism for converting into linear motion is formed.

  Therefore, in this electric brake device, the rotational driving force of the electric motor 5 is transmitted to the cylindrical rotating member 8 via the speed reduction mechanism composed of the worm 6 and the gear 7, and the rotational motion is transmitted to the first cam member 10, Each brake pad 3 is pressed against the disc rotor 2 by the second cam member 11 that is converted into a linear motion by the cam mechanism including the second cam member 11 and the plurality of tapered rollers 14 and that linearly moves.

  As shown in FIGS. 1 to 3, a cylindrical screw member is provided with a female screw 8a on the inner diameter surface of the small-diameter portion of the cylindrical rotating member 8, and a male screw 15a screwed on the female screw 8a. 15 is in contact with the rear end surface of the first cam member 10. On the inner diameter side of the cylindrical screw member 15, a drive shaft 17 that is rotationally driven by the parking brake lever 16 from the rear end side of the cylindrical rotating member 8 is coaxially inserted, and a cylindrical shape is formed on the outer diameter surface on the front end side. The member 18 is fitted in the spline 17 s so as to be movable in the axial direction, and the rotation of the cylindrical member 18 that rotates together with the drive shaft 17 is transmitted to the cylindrical screw member 15 via the one-way clutch 19. Yes.

  The one-way clutch 19 transmits the rotation of the drive shaft 17 only in the direction in which the cylindrical screw member 15 is driven forward toward the first cam member 10, and the cylindrical screw member 15 is connected to the cylindrical member 18 and the one-way clutch 19. Move forward together. The male screw 15a of the cylindrical screw member 15 that is screwed with the female screw 8a of the cylindrical rotating member 8 has a flank angle on the front surface of the thread that faces the front side so that the cylindrical screw member 15 is smoothly driven forward. It is a serrated screw smaller than the flank angle on the rear face of the thread.

  The drive shaft 17 is rotatably supported by a deep groove ball bearing 20 a between the cylindrical rotating member 8 and a needle roller bearing 20 b integrated with the one-way clutch 19, and is prevented from coming off by a retaining ring 21. ing. In addition, a hexagonal hole 17a is provided on the rear end surface of the drive shaft 17 and a claw member 22 is attached to the outer diameter surface for replacement work of a brake pad 3 to be described later. A notch groove 15b into which the claw member 22 is fitted is provided.

  The parking brake lever 16 is mounted with a wire 24 connected to the operation end of the parking brake, with the arm portion holding the rear end portion of the drive shaft 17 cut off by the bolts 23 from both sides. The return position is regulated by a stopper 25 attached to the casing 4. The rotation of the drive shaft 17 when the lever 16 is returned is interrupted by the one-way clutch 19 and is not transmitted to the cylindrical screw member 15.

  Therefore, the parking brake operating mechanism transmits the rotation of the drive shaft 17 driven to rotate by the lever 16 to the cylindrical screw member 15 via the cylindrical member 18 and the one-way clutch 19 and rotates. Is driven forward by the lead angle of the male screw 15a and the female screw 8a, and the first cam member 10 abutted on the tip thereof is pressed, and can be moved in the axial direction by fitting the splines 8s and 12s. The entire cam mechanism including the first cam member 10 and the second cam member 11 is moved forward to press the brake pads 3 against the disc rotor 2.

  FIG. 5 shows a state where the brake pad 3 is worn. When the brake pad 3 is worn, the pressed position changes so as to move forward. However, as described above, the cylindrical screw member 15 that is driven forward by operating the parking brake wears the brake pad 3. As the operation progresses, the entire cam mechanism including the first cam member 10 and the second cam member 11 that are movable in the axial direction is gradually pushed forward, and the standby position is held near the pressing position of the brake pad 3. Therefore, it is possible to naturally ensure excellent braking effectiveness responsiveness to both the electric brake and the parking brake.

  Next, a replacement work method when the brake pad 3 is worn will be described. As shown in FIG. 5, when the brake pad 3 is worn, the entire cam mechanism including the first cam member 10 and the second cam member 11 and the cylindrical screw member 15 move considerably forward. In this state, as shown in FIG. 6, the lever 16 and the retaining ring 21 are detached from the drive shaft 17, the drive shaft 17 is pushed to the back of the cylindrical member 18, and the claw member 22 attached to the outer diameter surface is cylindrical. The screw member 15 is fitted into a notch groove 15b provided at the rear end.

  After that, the hexagon wrench 26 is inserted into the hexagon hole 17a provided in the rear end surface, and the drive shaft 17 is rotated in the direction opposite to the rotation direction when the parking brake is operated, as shown by the arrow in FIG. The cylindrical screw member 15 is reversely rotated by the engagement of 22 and the notch groove 15b, and the cylindrical screw member 15 is pulled back to the initial position. In this state, the entire cam mechanism is pushed back with a finger or the like to replace the brake pad 3 with a new one. The drive shaft 17 may be reversely rotated by a driver or the like.

  In the embodiment described above, the tapered roller is used as the rolling element of the cam mechanism. However, a cylindrical roller or a ball can be used. The reduction mechanism for the rotational driving force of the electric motor and the cam mechanism for converting this rotational driving force into a linear driving force are limited to the worm gear type and the rolling element engagement type of the embodiment, respectively. However, other methods can be used.

A longitudinal sectional view showing an embodiment of an electric brake device Side view of FIG. Sectional view along line III-III in FIG. a is a sectional view showing a portion of the cam mechanism of FIG. 1, and b is a partial development view of the cam surface of a. 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 illustrating a method for replacing the worn brake pad in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Caliper 2 Disc rotor 3 Brake pad 4 Casing 5 Electric motor 5a Output shaft 6 Worm 7 Gear 8 Cylindrical rotating member 8a Female screw 8s Spline 9a, 9b Bearing 10, 11 Cam member 10a, 11a Cam surface 12 Anti-rotation member 12s Spline 13 Boot 14 Tapered roller 15 Cylindrical screw member 15a Male thread 15b Notch groove 16 Lever 17 Drive shaft 17a Hexagonal hole 17b Serration 17s Spline 18 Cylindrical member 19 One-way clutch 20a, 20b Bearing 21 Retaining ring 22 Claw member 23 Bolt 24 Wire 25 Stopper 26 Hexagon wrench

Claims (9)

  The rotational driving force of the electric motor is converted into a linear driving force, and the brake member is pressed against the member to be braked by this linear driving force, and the rotational driving force of the drive shaft driven by the operation end of the parking brake is converted into a linear driving force. In an electric brake device incorporating a parking brake operating mechanism that also converts the linear braking force against the braked member by this linear driving force, the rotational driving force of the electric motor is converted into a linear driving force by a cam mechanism. The electric brake device is characterized in that the rotational driving force of the drive shaft is converted into a linear driving force by a screw mechanism, and the conversion into the linear driving force is performed on the same axis.   A means for pressing the brake member against the member to be braked by coaxially converting to a linear driving force by the cam mechanism and the screw mechanism is provided with a cylindrical rotating member that transmits the rotational driving force of the electric motor. And a cam mechanism for converting the rotational motion into a linear motion in the axial direction and pressing the brake member against the member to be braked on the same axis on the axial front side of the cylindrical rotating member. Can be moved in the axial direction of the cylindrical rotating member, and a cylindrical screw member provided on the outer diameter surface with a male screw that engages with an internal screw provided on the inner diameter surface of the cylindrical rotating member is applied to the rear surface side of the cam mechanism. The drive shaft is coaxially inserted into the cylindrical screw member from the axial rear side of the cylindrical rotating member on the inner diameter side of the cylindrical screw member, and the cylindrical screw member is rotated via a one-way clutch. The cylindrical screw member on one side Provided with a screw mechanism that is driven forward in the axial direction by the rotation transmitted to the shaft, and the brake member is braked through the entire cam mechanism that is movable in the axial direction by the forward drive of the cylindrical screw member by the screw mechanism. The electric brake device according to claim 1, wherein the electric brake device is pressed against a member.   A first cam member that rotates together with the cylindrical rotary member on the inner diameter side of the cylindrical rotary member, is movable in the axial direction, and has a first cam surface on the front side; and the first cam member A second cam member that is axially movable on the front side of the first cam member and is provided with a second cam surface facing the first cam surface on the rear side, and the first cam surface and the second cam surface And a plurality of rolling elements that engage with these cam surfaces and convert the rotational motion of the first cam member into the linear motion in the axial direction of the second cam member. The electric brake device described.   The electric brake device according to claim 3, wherein a tapered roller is used for the rolling element.   The male screw of the cylindrical screw member is a serrated screw having a flank angle on the front surface of the thread facing the front side of the cylindrical screw member that is smaller than a flank angle on the rear surface of the thread. Electric brake device.   A cylindrical member is fitted on the outer diameter surface of the drive shaft by a spline so as to be movable in the axial direction, and a one-way clutch for transmitting rotation in one direction to the cylindrical screw member is fitted on the cylindrical member. The electric brake device according to any one of 2 to 5.   7. Only one of the bearings that support the cylindrical rotating member is configured to support a radial load and a thrust load, and the remaining other bearings are configured to support only a radial load. The electric brake device described.   The electric brake device according to any one of claims 1 to 7, wherein a rotational driving force of the electric motor is transmitted to the cylindrical rotating member via a speed reduction mechanism.   The electric brake device according to claim 8, wherein the speed reduction mechanism uses a worm gear.

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