JP2005233228A - Electric brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric brake device of structure capable of assembling a compact mechanical brake operating mechanism and while capable of preventing hindrance of effect of an electric brake. <P>SOLUTION: A gear 12 is fitted to a peripheral surface of a nut 6 of a ball screw mechanism, which is integrally formed with a rotor of an electric motor, through a one-way clutch 11. A lever 13 to be engaged with the gear 12 is provided, and when the lever 13 is tilted for operation to normally rotate the gear 12, the one-way clutch 11 is let in, and the nut 6 is turned together in the normal rotating direction, and a screw shaft 8 is linearly driven forward to push a brake pad 3a. When the lever 13 is tilted for return to reversely rotate the gear 12, the one-way clutch 11 is let out, and the gear 12 is idly rotated. The mechanical brake operating mechanism is thereby assembled compact, and even in the condition wherein the mechanical brake is operated, effect of the electric brake is not hindered. <P>COPYRIGHT: (C)2005,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 more particularly, an electric type incorporating an operating mechanism of a mechanical brake. it relates to the brake system.

  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. can, electric brake apparatus which can be designed compact has attracted 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. There, the conversion mechanism from the rotary driving force to the linear driving force, the screw mechanism the nut and the screw shaft is screwed is widely adopted.

  Wherein the screw mechanism that converts the linear driving force rotational driving force of the electric motor, and the type of linear driving the screw shaft was rotated the nut, on the contrary, the type of the screw shaft are rotationally driven to linearly drive the nut there is a door. Further, these screw mechanism, the nut and the screw shaft to that using conventional screw mechanism to be screwed directly (e.g., see Patent Document 1.), Nut and screw shaft screwed through the ball ball there is a one using a screw mechanism (for example, see Patent Document 2.).

  In the case of using an ordinary screw mechanism like that described in Patent Document 1, since the rotational frictional resistance of the screw is large, many nuts or screw shafts are rotationally driven via a gear reduction mechanism. On the other hand, when a ball screw mechanism is used as in Patent Document 2, since the rotational frictional resistance of the screw is small, the nut is rotated integrally with the rotor of the electric motor so that the screw shaft is linearly driven. which was often. Those using the ball screw mechanism, for heavy and bulky gear reduction mechanism is unnecessary, there is an advantage that the electric brake apparatus which is attached to the unsprung vehicle can lightweight design compact.

  Further, the electric brake apparatus, there is one that incorporates an actuating mechanism for the mechanical brake to be used in parking or the like (e.g., see Patent Document 3.). Those described in Patent Document 3, with the screw shaft ordinary screw mechanism through a gear reduction mechanism driven to rotate linearly drives the nut, the axial end portion of the screw shaft via the ball ramp mechanism and the clutch mechanism the rotary shaft for transmitting a rotational force provided by rotating the rotary axis of the lever, so that linearly drives the nut by rotating the screw shaft.

JP 2001-3967 JP (2-3 pages, Fig. 1) JP 2002-213505 JP (2-4 pages, 1-2 diagram) Utility Model Registration Gazette No. 2546348 (page 2-4, Fig. 1)

  The electric brake apparatus incorporating the actuation mechanism of the mechanical brake disclosed in Patent Document 3 described above, by connecting the rotary shaft in series through the ball ramp mechanism and the clutch mechanism to the shaft end of the screw shaft of the screw mechanism Since the screw shaft is rotationally driven, it cannot be applied to the type that rotationally drives the nut of the screw mechanism, and the axial length becomes long so that the vehicle spring does not interfere with the wheel. there is difficult to attach to the bottom problem.

  The electric brake apparatus disclosed in Patent Document 3, since the gears of the gear reduction mechanism in the axial end portion of the screw shaft is mounted, the rotary shaft screw shaft in the clutch mechanism in order to twist the mechanical brake and the bound state, even by operating the electric motor depresses the brake pedal, the locking screw shaft is also made problem ineffective electric brake.

  An object of the present invention, the actuation mechanism of the mechanical brake can be incorporated compactly, and is to provide an electric brake apparatus which effectiveness of the electric brake is not hindered.

  In order to solve the above-described problems, the present invention rotates a nut of a screw mechanism with a rotational driving force of an electric motor, linearly drives a screw shaft that is screwed into the nut, and brakes with the linear driving force of the screw shaft. the electric brake apparatus for pressing the member to the braked member by attaching the gear through a one-way clutch to the outer peripheral surface of the nut, the lever having a tooth profile that meshes with the gear provided, the gears by operating the lever When the forward rotation is performed, the one-way clutch is engaged, the nut is rotated with the gear, the screw shaft is linearly driven forward to press the brake member, and the lever is operated to return the gear. When reversely rotating, the one-way clutch is disengaged and only the gear is idled.

  That is, by attaching a gear through a one-way clutch to the outer peripheral surface of the nut of the screw mechanism, a lever having a tooth profile that meshes with the gear provided, when rotated forward gear by operating the lever, the one-way clutch When the nut is rotated in the forward rotation direction and the screw shaft is linearly driven forward to press the brake member, and the lever is operated backward to rotate the gear backward, the one-way clutch is disengaged. Thus, by allowing only the gears to idle, the mechanical brake operating mechanism can be incorporated in a compact manner, and the nut can be rotated forward by the electric motor even when the mechanical brake is in effect. when obtained by the gear becomes the one-way clutch becomes relatively reverse rotation switching, unimpeded effectiveness of the electric brake, the screw shaft is linearly driven to the brake member pressing side It was so. When releasing the electric brake, reverse the electric motor, or stop the electric motor and press and urge the screw shaft to the rear side opposite to the brake member. The screw shaft can escape from the brake member to the rear by an amount corresponding to the axial direction of the screw mechanism.

  Also, in this electric brake device, when the nut of the screw mechanism tries to reversely rotate, the gear rotates relatively forward and the one-way clutch is engaged. However, the nut constrained by the gear engaged with the lever can only reversely rotate in the rotational direction of the gear, and the screw shaft that presses the brake member has an axial direction due to the rotational direction of the gear. only another minute not return to the rear. Therefore, even if the brake member wears and its pressing position gradually changes forward, the screw shaft after pressing the brake member is always held close to the pressing position, so naturally ensuring excellent braking effectiveness responsiveness can do.

  Said screw mechanism, by which the nut and screw shaft and a ball screw mechanism screwed through the ball, as unnecessary heavy and bulky gear reduction mechanism, to design the electric brake apparatus more compact and lightweight it can.

  The electric brake device according to the present invention includes a lever having a tooth shape that engages with a gear by attaching a gear to an outer peripheral surface of a nut of a screw mechanism that converts the rotational driving force of the electric motor into a linear driving force via a one-way clutch. When the gear is rotated forward by operating this lever, the one-way clutch is engaged, the nut is rotated in the forward rotation direction, and the screw shaft is linearly driven forward to press the brake member. When the lever is turned back and the gear is rotated in reverse, the one-way clutch is disengaged and only the gear is idling, so that the mechanical brake operating mechanism can be compactly incorporated, and , even in a state where twist mechanical brake, a nut free to rotate drive the direction in which the one-way clutch is a switching in the electric motor, can linearly drive the screw shaft to the brake member pressing side, That there is no also hindered effectiveness of Doshiki brake.

  Further, in this electric brake device, even if the electric motor is reversely rotated or stopped when the brake is released, the nut can only reversely rotate by the amount of rotation of the gear, and the screw shaft that presses the brake member since axial backlash caused by the rotational direction backlash only return backwards, be varied forward its pressing position gradually brake member is worn, the screw shaft is always pressing position near the rear brake member pressing Therefore, it is possible to naturally ensure excellent braking effectiveness.

  By making the screw mechanism a ball screw mechanism in which a nut and a screw shaft are screwed together via a ball, a heavy and bulky gear reduction mechanism is unnecessary, and the electric brake device can be designed to be more compact and lightweight. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1A and 1B, this electric brake device has brake pads 3a and 3b as brake members arranged on both sides of a disc rotor 2 as a braked member inside the caliper 1. was a disc brake, with a stator 5 of an electric motor fixed to the inner peripheral surface of the motor casing 4 attached to the caliper 1, the nut 6 of a ball screw mechanism which is formed in the rotor and integral with the caliper 1 and the motor casing 4 The shaft 6 is rotatably supported by a pair of bearings 9, and the nut 6 is rotationally driven by an electric motor, whereby the screw shaft 8 that is screwed into the nut 6 via the ball 7 is linearly driven, and the front end side of the screw shaft 8 in addition to press the brake pad 3a in the disc rotor 2, to press the brake pad 3b to the disc rotor 2 which is mounted to the caliper 1 by the reaction force of the pressing It is intended. Note that the front end surface of the screw shaft 8 notch portion 8a is provided a detent which engages with the protrusion of the brake pad 3a side, the interior of the motor casing 4 is mounted between the caliper 1 and the threaded shaft 8 Boots It is sealed at 10.

  Further, the outer peripheral surface of the nut 6 of the ball screw mechanism gear 12 is mounted via a one-way clutch 11, the lever 13 having a tooth profile that meshes with the gear 12, is pivotally secured to the shaft bolt 14 attached to the casing 4 ing. These are intended to constitute the actuating mechanism of the mechanical brake to be used in parking or the like, the lever 13 is connected by wire 15 to a motor or the like which is driven by the hand lever or switch is an operation end of the mechanical brake It is adapted to be tilting. Further, the lever 13, the tension coil spring 16 for returning the tilt when the mechanical brake is released, the stopper 17 for restricting the back position of the tilt is provided.

  The one-way clutch 11, as shown in FIG. 2 (a), (b), a plurality of needle rollers 18 serving as engaging elements only urges a spring 19 in the circumferential direction in one direction to the wedge surface 20 As shown by the arrows in FIG. 2A, when the gear 12 is rotated forward clockwise or when the nut 6 is rotated reversely, each needle roller 18 is moved to each wedge. The clutch engaged with the surface 20 is engaged, and the gear 12 and the nut 6 try to rotate. Further, as indicated by an arrow in FIG. 2B, when the gear 12 is rotated counterclockwise or when the nut 6 is rotated forward, each needle roller 18 is engaged with each wedge surface 20. The clutch 12 is not engaged and the gear 12 or the nut 6 is idled independently.

  The following describes the operation method of the electric brake and the mechanical brake as described above. First, the electric brake, the electric motor is activated by depression signal of a brake pedal (not shown), rotated forward nut 6 as the screw shaft 8 is linearly driven forward. Accordingly, at this time, the clutch is disengaged as shown in FIG. 2B, and the nut 6 rotates forward without being constrained by the gear 12, and the screw shaft 8 linearly driven forward presses the brake pad 3a. . Further, the electric motor rotates the nut 6 in reverse by a brake pedal release signal. At this time, the clutch is engaged as shown in FIG. 2A, and the nut 6 is restrained by the gear 12 so that the rotation direction of the gear 12 is reversely rotated as much as possible, and the screw shaft 8 is the axial direction of the ball screw mechanism. only backlash Back to the rear away from the brake pad 3a. The electric brake may be released by pressing and urging the screw shaft 8 backward with a spring or the like and returning the screw shaft 8 backward only by stopping the electric motor.

  Next, regarding the operation of the mechanical brake, as shown by an arrow in FIG. 1B, when the lever 13 is tilted counterclockwise by the pulling force of the wire 15, the gear 12 rotates in the clockwise direction. to, a clutch oN state shown in FIG. 2 (a). Thus, the nut 6 of the ball screw mechanism is rotating together with the gear 12 in the forward rotational direction, the screw shaft 8 is linearly driven forward to press the brake pad 3a. When the tensile force of the wire 15 is released, the lever 13 urged in the reverse direction by the tension coil spring 16 is tilted back in the clockwise direction, and the gear 12 is rotated in the counterclockwise direction, and FIG. a clutch switching state shown in b). Therefore, at this time, only the gear 12 rotates idly until the lever 13 is tilted to the return position regulated by the stopper 17 and, similarly to the case of releasing the electric brake, the rotation direction of the gear 12 is caused by rattling. The screw shaft 8 returns to the rear away from the brake pad 3a by an amount corresponding to the axial direction of the ball screw mechanism.

  Figure 3 shows a state in which the brake pads 3a, 3b is worn. Brake pads 3a, when 3b is worn, the pressing position is changed so moves forward, as described above, the screw shaft 8 after pressing the brake pad 3a is due to the rotational direction backlash of the gear 12 Since the axial direction of the ball screw mechanism only returns to the rear, the ball screw mechanism is always held near the pressing position. Accordingly, not only when the electric brake is operated, but also when the mechanical brake is operated, the brake pad 3a can be pressed with a slight linear driving amount of the screw shaft 8, and excellent responsiveness of the brake effect is ensured. can do.

  Next, a replacement method when the brake pads 3a and 3b are worn will be described. As shown in FIG. 3, brake pads 3a, when 3b is worn, the screw shaft 8 is held fairly close to the pressed position moved forward. In this state, as shown in FIG. 4 (a), (b), and remove the lever 13 which meshes with the gear 12, rotated in reverse nut 6 by an electric motor. At this time, although the clutch ON state shown in FIG. 2 (a), the lever 13 is detached gear 12 and the nut 6 is free to rotate together. Therefore, the screw shaft 8 is linearly driven backward by the reverse rotation of the nut 6, it is possible to open the space for exchange between the brake pads 3a.

  In the embodiment described above, although using a ball screw mechanism converting mechanism of the rotational drive force of the electric motor, electric brake apparatus according to the present invention also applies to those using conventional screw mechanism for this conversion mechanism be able to. Further, the one-way clutch constituting the actuation mechanism of the mechanical brake has been adopted as the type using a needle roller on the engaging member, the one-way clutch is not limited to those embodiments, engagement Other types using balls, sprags, or the like for the combination can also be used.

a is a longitudinal sectional view showing an embodiment of the electric brake device, and b is a sectional view taken along line Ib-Ib of a. a, b is a sectional view illustrating a on-off state of the one-way clutch of FIG. 1, respectively Longitudinal sectional view showing a state in which the brake pads are worn in FIG a is a longitudinal sectional view illustrating a method of replacing worn brake pads of FIG. 3, b is a sectional view taken along line IVb-IVb of a

Explanation of symbols

1 caliper 2 disk rotor 3a, 3b brake pad 4 motor casing 5 stator 6 nut 7 Ball 8 screw shaft 8a notch 9 bearing 10 boots 11 one-way clutch 12 the gear 13 the lever 14 shaft bolt 15 wire 16 tension coil spring 17 stopper 18 Needle roller 19 Spring 20 Wedge surface

Claims (2)

  In an electric brake device that rotates a nut of a screw mechanism by a rotational driving force of an electric motor, linearly drives a screw shaft that is screwed to the nut, and presses a brake member against a member to be braked by the linear driving force of the screw shaft. A gear is attached to the outer peripheral surface of the nut via a one-way clutch, and a lever having a tooth shape meshing with the gear is provided. When the gear is rotated forward by operating the lever, the one-way clutch is engaged. When the nut is rotated with the gear and the screw shaft is linearly driven to the front side pressing the brake member, and the lever is returned to rotate the gear reversely, the one-way clutch is disengaged. Thus, the electric brake device is characterized in that only the gear is idled.   It said screw mechanism, electric brake apparatus according to claim 1, wherein the nut and the screw shaft is a ball screw mechanism screwed through the ball.

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