WO2005078309A1

WO2005078309A1 - Motor-driven brake device

Info

Publication number: WO2005078309A1
Application number: PCT/JP2005/002429
Authority: WO
Inventors: Ken Yamamoto
Original assignee: Ntn Corporation
Priority date: 2004-02-17
Filing date: 2005-02-17
Publication date: 2005-08-25
Also published as: JP2005233228A; JP4439285B2

Abstract

A motor-driven brake device enabling the operating mechanism of a mechanical brake to be compactly assembled therein and preventing the effect of a motor-driven brake from being obstructed. A gear (12) is fitted, through a one-way clutch (11), onto the outer peripheral surface of the nut (6) of a ball screw mechanism formed integrally with the rotor of an electric motor and a lever (13) engageable with the gear (12) is installed. When the gear (12) is rotated in the forward direction by tilting the lever (13), the one-way clutch (11) is engaged, the nut (6) is rotated in the forward direction together with the lever, and a screw shaft (8) is linearly driven forward to press the brake pad (3a). When the lever (13) is tilted back to reversely rotate the gear (12), the one-way clutch (11) is disengaged to run idle the gear (12). In this state, the operation mechanism of the mechanical brake can be compactly assembled in the device, and the effect of the motor-driven brake is not obstructed even if the mechanical brake is applied.

Description

Specification

Electric brake device

Technical field

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 particularly relates to an operation mechanism of a mechanical brake. The present invention relates to a built-in electric brake device. Background art

[0002] Hydraulic-type brakes have been widely used as vehicle brake devices. In recent years, with the introduction of advanced brake controls such as ABS (Antilock Brake System), these controls can be performed without complicated hydraulic circuits. Attention is being paid to electric brake devices that can be designed and compact. An electric brake device operates an electric motor in response to a brake pedal depression signal or the like, 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 the linear driving force. There are many screw mechanisms in which nuts and screw shafts are screwed together to change from rotary driving force to linear driving force.

[0003] A screw mechanism that converts the rotational driving force of the electric motor into a linear driving force includes a type in which the nut is rotated to linearly drive the screw shaft, and a type in which the screw shaft is rotationally driven to rotate the nut. There is a type that drives linearly. In addition, these screw mechanisms use a normal screw mechanism in which a nut and a screw shaft are directly screwed (for example, see Patent Document 1), and a ball in which the nut and the screw shaft are screwed through a ball. Some use a screw mechanism (see, for example, Patent Document 2).

[0004] When an ordinary screw mechanism is used, such as that described in Patent Document 1, the rotational frictional resistance of the screw is large, so that the nut or the screw shaft is rotationally driven via a gear reduction mechanism. There are many things. On the other hand, when a ball screw mechanism is used, as described 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 to drive the screw shaft linearly. There are many things like that. Since the use of the ball screw mechanism does not require a heavy and bulky gear reduction mechanism, there is an advantage that the electric brake device mounted under the spring of the vehicle can be designed to be compact and lightweight. [0005] Further, in the electric brake apparatus, there is incorporated a hydraulic Organization of the mechanical brake to be used in parking or the like (e.g., see Patent Document 3.) _0. of described in Patent Document 3 Is a rotary shaft that drives the nut linearly by rotating the screw shaft of a normal screw mechanism via a gear reduction mechanism, and transmitting torque to the shaft end of the screw shaft via a ball ramp mechanism and a clutch mechanism. By rotating the rotating shaft by operating a lever, the screw shaft is driven to rotate and the nut is driven linearly.

Patent Document 1: Japanese Patent Application Laid-Open No. 2001-3967 (pages 2-3, FIG. 1)

Patent Document 2: Japanese Patent Application Laid-Open No. 2002-213505 (Pages 2-4, Fig. 12)

Patent Document 3: Japanese Utility Model Registration Publication No. 2546348 (Pages 2-4, Fig. 1)

Disclosure of the invention

Problems to be solved by the invention

[0007] The electric brake device incorporating the mechanical brake operating mechanism described in Patent Document 3 described above has a rotary shaft connected in series to a shaft end of a screw shaft of a screw mechanism via a ball ramp mechanism and a clutch mechanism. To rotate the screw shaft, so that it cannot be applied to the type that rotates the nut of the screw mechanism, and if the length in the axial direction is long, it does not interfere with the wheel. However, there is a problem that it is difficult to attach it below the spring of the vehicle.

[0008] Further, in the electric brake device described in Patent Document 3, since a gear of a gear reduction mechanism is attached to the shaft end of the screw shaft, the screw shaft is closed in order to operate the mechanical brake. When the electric motor is operated by depressing the brake pedal when the rotary mechanism is connected to the rotary shaft by the lever mechanism, there is also a problem that the screw shaft is locked and the electric brake cannot work.

[0009] Therefore, an object of the present invention is to provide an electric brake device in which an operation mechanism of a mechanical brake can be incorporated compactly and the effectiveness of the electric brake is not hindered.

Means for solving the problem

[0010] In order to solve the above-described problems, the present invention is to rotate a nut of a screw mechanism by a rotational driving force of an electric motor to linearly drive a screw shaft screwed to the nut, and to linearly drive the screw shaft. In an electric brake device that presses a brake member against a member to be braked by power, a gear is attached to an outer peripheral surface of the nut via a one-way clutch, and a tooth profile meshing with the gear is provided. When the lever is operated to rotate the gear forward, the one-way clutch is engaged, the nut rotates with the gear, and the screw shaft presses the brake member. The one-way clutch is disengaged and only the gear is idled when the gear is driven linearly to the side and the lever is returned to operate the gear in reverse.

That is, when a gear is attached to the outer peripheral surface of a nut of a screw mechanism via a one-way clutch, a lever having a tooth profile meshing with the gear is provided, and the lever is operated to rotate the gear forward. Then, when the one-way clutch is engaged, the nut rotates in the forward rotation direction and the screw shaft is driven linearly forward to press the brake member, and the lever is returned to operate the gear in reverse. The one-way clutch is disengaged, and only the gears run idle, enabling the mechanical brake operation mechanism to be compactly incorporated.Even when the mechanical brake is activated, the electric motor When the nut is rotated forward, the gear rotates relatively in the reverse direction, the one-way clutch is disengaged, and the effectiveness of the electric brake is not hindered. It was to be driven. When releasing the electric brake, the rotation direction of the gear may be reduced by reversing the electric motor or by stopping the electric motor and pressing the screw shaft to the rear side opposite to the brake member. The screw shaft can be released to the rear of the brake member force by an amount corresponding to the axial direction of the screw mechanism. The direction of rotation of the gears must be sufficient to prevent the brake pads from dragging.

[0012] Further, in this electric brake device, when the nut of the screw mechanism tries to rotate in the reverse direction, the gear rotates relatively in the forward direction and the one-way clutch is engaged, so that the electric motor is used when the brake is released. Even if the gear rotates reversely or stops, the nut constrained by the gear engaged with the lever can only reverse the rotation of the gear by the rotation direction of the gear, and the screw shaft pressing the brake member has the rotation direction of this gear The axial direction caused by the above only returns backward. Therefore, even if the brake member wears and its pressing position gradually changes forward, the screw shaft after pressing the brake member is always kept close to the pressing position, so that excellent braking effect responsiveness is naturally achieved. Can be secured.

[0013] By making the screw mechanism a ball screw mechanism in which the nut and the screw shaft are screwed together via balls, a heavy and bulky gear reduction mechanism is not required, and the electric brake device can be further improved. It can be designed to be compact and lightweight.

The invention's effect

[0014] In the electric brake device of the present invention, a gear is attached via a one-way clutch to an outer peripheral surface of a nut of a screw mechanism for converting a rotational driving force of an electric motor into a linear driving force, and the gear is connected to the gear. When a lever with a matching tooth profile is provided and this gear is operated to rotate the gear forward, the one-way clutch is engaged, the nut rotates in the forward rotation direction, and the screw shaft turns the brake member. When the gears are driven linearly forward to push forward and the gears are rotated in the reverse direction by returning the levers, the one-way clutch is disengaged, and only the gears idle. Even when the mechanical brake is activated, the nut can be freely rotated by the electric motor in the direction in which the one-way clutch is disengaged, and the screw shaft is used as a brake member. Straight to pressing side Can dynamically, it it also the effectiveness of the electric brake is prevented.

[0015] Further, in this electric brake device, even if the electric motor is reversed or stopped at the time of releasing the brake, the nut can only reverse the rotation direction of the gear, and the screw shaft pressing the brake member has Since the axial direction due to the rotation direction of the gear only returns backward by a certain amount, even if the brake member wears and the pressing position gradually changes forward, the screw shaft after the brake member is pressed Is always kept close to the pressed position, and excellent responsiveness of braking effect can be naturally ensured.

[0016] By making the screw mechanism a ball screw mechanism in which a nut and a screw shaft are screwed together via balls, a heavy and bulky gear reduction mechanism is not required, and the electric brake device is made more compact and lightweight. Can be designed.

Brief Description of Drawings

[FIG. 1] a is a longitudinal sectional view showing an embodiment of the electric brake device, and b is a sectional view taken along the line lb-lb of a.

[FIG. 2] a and b are cross-sectional views illustrating the on / off state of the one-way clutch in FIG. 1, respectively.

FIG. 3 is a longitudinal sectional view showing a state in which the brake pad of FIG. 1 is worn.

[FIG. 4] a is a longitudinal sectional view illustrating a method of replacing the worn brake pad of FIG. 3, and b is a sectional view taken along a line IVb IVb of a. Explanation of reference numerals

1 Caliper

2 Disk rotor

3a, 3b brake pads

4 Motor casing

5 Stator

6 nut

7 ball

8 Screw shaft

8a Notch

9 Bearing

10 boots

11 One-way clutch

12 Difficult

13 Reno

14-axis bonoleto

15 wires

16 Extension coil spring

17 Stopper

18 Needle roller

19 spring

20 Wedge surface

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. This electric brake device

As shown in FIGS. 1 (a) and 1 (b), disc brakes having brake pads 3a and 3b as brake members opposingly arranged on both sides of a disc rotor 2 as a member to be braked inside a caliper 1. The stator 5 of the electric motor is fixed to the inner peripheral surface of the motor casing 4 attached to the caliper 1, and the nut 6 of the ball screw mechanism formed integrally with the rotor is connected to the caliper 1. It is rotatably supported by a pair of bearings 9 on the motor casing 4 and the nut 6 is rotated by an electric motor, so that the screw shaft 8 screwed to the nut 6 via the ball 7 is linearly driven. The brake pad 3a is pressed against the disk rotor 2 at the front end side of the screw shaft 8, and the brake pad 3b attached to the caliper 1 is also pressed against the disk rotor 2 by the reaction force of this pressing force. A notch 8a for preventing rotation is provided on the front end face of the screw shaft 8 to engage with the projection on the brake pad 3a side.The inside of the motor casing 4 is mounted between the caliper 1 and the screw shaft 8. Sealed with boots 10.

A gear 12 is mounted on the outer peripheral surface of the nut 6 of the ball screw mechanism via a one-way clutch 11, and a lever 13 having a tooth shape meshing with the gear 12 is provided on a shaft mounted on the casing 4. It is pivoted on bolt 14. These constitute an operating mechanism of a mechanical brake used for parking and the like, and a lever 13 is connected to a manual lever, an operating end of the mechanical brake, a motor driven by a switch, and the like via a wire 15. The tilt operation is performed. Further, the lever 13 is provided with a tension coil spring 16 for returning the tilt when the mechanical brake is released, and a stopper 17 for regulating the return position of the tilt.

As shown in FIGS. 2 (a) and 2 (b), the one-way clutch 11 urges a plurality of -1 dollar rollers 18 as engaging elements in the circumferential direction by a spring 19 to form a wedge surface 20. As shown by arrows in FIG. 2 (a), when the gear 12 is rotated clockwise forward or the nut 6 is rotated reversely, -The clutch 18 is engaged so that the roller 18 engages with each wedge surface 20, and the gear 12 and the nut 6 try to rotate. When the gear 12 is rotated counterclockwise or the nut 6 is rotated forward, as shown by the arrow in FIG. And the gear 12 or the nut 6 idles alone.

Hereinafter, a method of operating the electric brake and the mechanical brake described above will be described. First, with respect to the electric brake, the electric motor is started by a depression signal of a brake pedal (not shown), and the nut 6 is rotated forward so that the screw shaft 8 is linearly driven forward. Therefore, at this time, the clutch is in the disengaged state shown in FIG. 2 (b), the nut 6 rotates forward without being restricted by the gear 12, and the screw shaft 8 linearly driven forward moves the brake pad 3a. Press To do. Further, the electric motor rotates the nut 6 in the reverse direction in response to the brake pedal release signal. At this time, the clutch is engaged as shown in FIG. 2 (a), the nut 6 is restrained by the gear 12, the rotation direction of the gear 12 reverses only by a certain amount, and the screw shaft 8 is the shaft of the ball screw mechanism. Return backward away from brake pad 3a by the amount of direction. The electric brake may be released by pressing the screw shaft 8 rearward on the return side with a spring or the like and returning the screw shaft 8 rearward 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 clockwise. Then, the clutch rotates forward and the clutch is engaged as shown in FIG. Accordingly, the nut 6 of the ball screw mechanism rotates in the forward rotation direction with the gear 12, and the screw shaft 8 is linearly driven forward to press the brake pad 3a. When the pulling force of the wire 15 is released, the lever 13 urged in the opposite direction by the tension coil spring 16 is tilted back clockwise and the gear 12 rotates counterclockwise in the reverse direction. The clutch is in the disengaged state shown in (b). Accordingly, at this time, only the gear 12 idles until the lever 13 is tilted to the return position regulated by the stopper 17, and the rotation direction of the gear 12 is changed in the same manner as when the electric brake is released. This causes the screw shaft 8 to return to the rear where it separates from the brake pad 3a by the axial direction of the ball screw mechanism.

FIG. 3 shows a state in which the brake pads 3a and 3b are worn. When the brake pads 3a and 3b wear, the pressing position changes to move forward, but as described above, the screw shaft 8 after pressing the brake pad 3a is caused by the rotation direction of the gear 12 Since the axial direction of the ball screw mechanism only returns backward by a certain amount, it is always held near the pressed position. Therefore, not only when operating the electric brake but also when operating the mechanical brake, the brake pad 3a can be pressed with a small amount of linear drive of the screw shaft 8, ensuring excellent responsiveness of the braking effect. can do.

Next, a replacement method when the brake pads 3a and 3b are worn will be described. As shown in FIG. 3, when the brake pads 3a and 3b are worn, the screw shaft 8 is held near the pressing position that has moved considerably forward. In this state, as shown in FIGS. 4 (a) and 4 (b), the lever 13 which engages with the gear 12 is removed, and the nut 6 is rotated reversely by the electric motor. In this case, Fig. 2 (a ), The gear 12 and the nut 6 rotate freely because the force lever 13 for engaging the clutch is removed. Therefore, the screw shaft 8 is linearly driven backward by the reverse rotation of the nut 6, and a space for replacement can be opened between the nut 6 and the brake pad 3a.

In the above-described embodiment, the ball screw mechanism is used as the mechanism for converting the rotational driving force of the electric motor. However, the electric brake device according to the present invention is also applied to a mechanism using a normal screw mechanism for this modification. be able to. In addition, a one-way clutch that constitutes an operating mechanism of a mechanical brake employs a type using a one-dollar roller as an engagement element. This one-way clutch is not limited to the embodiment. Another type using a ball-and-plug for the engaging element may be employed.

Claims

The scope of the claims

[1] An electric type in which the nut of the screw mechanism is rotated by the rotational driving force of the electric motor to linearly drive a screw shaft screwed to the nut, and the linear driving force of the screw shaft presses the brake member against the member to be braked. In the brake device, a gear is attached to the outer peripheral surface of the nut via a one-way clutch, and a lever having a tooth profile meshing with the gear is provided. When the lever is operated to rotate the gear forward, When the one-way clutch is engaged, the nut rotates with the gear, the screw shaft is linearly driven forward to press the brake member, and the lever is returned to rotate the gear in reverse. The one-way clutch is disengaged, and only the gear rotates idle.

2. The electric brake device according to claim 1, wherein the screw mechanism is a ball screw mechanism in which the nut and a screw shaft are screwed via balls.