JP2005069398A - Electric brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve responsiveness when changing braking force of an electric brake device. <P>SOLUTION: This electric brake device is provided with a brake disk 13 to be rotated with wheels, a brake piston 15 for braking the brake disk 13, an electric motor M, a planetary gear mechanism P for connecting the electric motor M to the brake piston 15, and a band brake device B for permitting and inhibiting transmission of driving force of the planetary gear mechanism P. When restriction of a ring gear 33 of the planetary gear mechanism P is released by releasing the band brake B, while driving the electric motor M for normal rotation, in the case of anti-lock brake control requiring high responsiveness, since driving force of the electric motor M is not transmitted to the brake piston 15, responsiveness to increase and decrease of the driving force is improved by operating/stopping the band brake B each other, while driving the electric motor M for normal rotation, and effective anti-lock brake control is thereby enabled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric brake device in which a braking member that brakes a braked member that rotates with a wheel is driven by an electric motor.

  In general, in the conventional brake device, a brake piston provided in a brake caliper is driven by hydraulic pressure generated by a master cylinder or a hydraulic pump, and a brake pad is pressed against a brake disk by the brake piston to generate a braking force. .

Japanese Patent Application Laid-Open Publication No. 2004-151867 discloses a method of driving a brake piston by converting a rotational force generated by an electric motor into a thrust by a reduction gear and a screw mechanism instead of driving the brake piston by hydraulic pressure. According to this brake device, the braking force can be increased, held, and decreased by changing the rotation direction of the electric motor to advance, stop, and retract the brake piston.
JP-A-11-321599

  By the way, although what was described in the said patent document decelerates the rotational force of an electric motor with a reduction gear, transmits it to a screw mechanism, drives a brake piston with a screw mechanism, and generates braking force. If the speed reduction ratio of the reduction gear is increased to increase the braking force, there is a problem that the response from when the electric motor is driven to when the braking force rises is lowered. In addition, when performing anti-lock brake control that increases or decreases the braking force at short time intervals, it is necessary to cause the electric motor to rotate forward, stop, reverse, stop, forward ... There is a further problem of reduction.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to improve responsiveness when changing the braking force of an electric brake device.

  In order to achieve the above object, according to the invention described in claim 1, a braked member that rotates together with a wheel, a braking member that brakes the braked member, an electric motor capable of normal rotation and reverse rotation, A driving force transmission mechanism that connects the electric motor and the braking member, causes the braking member to approach the member to be braked by normal rotation of the electric motor, and separates the braking member from the member to be braked by reverse rotation of the electric motor; Driving force transmission control means for permitting and prohibiting the transmission of the driving force, and prohibiting the driving force transmission of the driving force transmission mechanism by the driving force transmission control means during the forward rotation of the electric motor. An electric brake device is proposed in which the braking member is separated from the member to be braked by a reaction force.

  According to the invention described in claim 2, in addition to the configuration of claim 1, the driving force transmission mechanism is a planetary gear mechanism having three elements of a sun gear, a planetary carrier, and a ring gear, and the three elements The first element is connected to the electric motor, the second element is connected to the braking member, and the third element is connected to the driving force transmission control means to permit or prohibit rotation. An electric brake device is proposed.

  According to the invention described in claim 3, in addition to the configuration of claim 2, an electric brake device is proposed in which the second element is connected to the braking member via a ball screw mechanism. .

  The brake disc 13 of the embodiment corresponds to the braked member of the present invention, the brake piston 15 of the embodiment corresponds to the braking member of the present invention, and the sun gear 31 of the embodiment corresponds to the first element of the present invention. The planetary carrier 32 of the embodiment corresponds to the second element of the present invention, the ring gear 33 of the embodiment corresponds to the third element of the present invention, and the band brake device B of the embodiment has the driving force of the present invention. Corresponding to the transmission control means, the planetary gear mechanism P of the embodiment corresponds to the driving force transmission mechanism of the present invention.

  According to the configuration of claim 1, during normal braking where high responsiveness is not required, the electric motor is driven forward and the braking force is caused to approach the braked member by the driving force transmission mechanism to generate the braking force. The braking force can be released by driving the electric motor in reverse and separating the braking member from the member to be braked by the driving force transmission mechanism. In anti-lock brake control, which requires high responsiveness, if the driving force transmission control means prohibits the driving force transmission of the driving force transmission mechanism while driving the electric motor in the normal direction, the braking force is applied by the reaction force from the braked member. Is separated from the member to be braked. Therefore, it is possible to improve the response of the increase and decrease of the braking force by simply executing the driving force transmission control means alternately at predetermined time intervals. Lock brake control can be enabled.

  According to the configuration of claim 2, the driving force transmission mechanism is constituted by a planetary gear mechanism having three elements, that is, a sun gear, a planetary carrier, and a ring gear, and the first element of the three elements of the planetary gear mechanism is connected to the electric motor. Since the second element is connected to the braking member and the third element is connected to the driving force transmission control means to permit or prohibit rotation, the layout of the electric motor, the braking member, and the driving force transmission control means can be freely set. The degree can be increased.

  According to the configuration of the third aspect, since the second element is connected to the braking member via the ball screw mechanism, the rotation of the second element can be efficiently converted into the longitudinal movement of the braking member.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 3 show an embodiment of the present invention. FIG. 1 is a cross-sectional view of an electric brake device, FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1, and FIG. It is explanatory drawing.

  As shown in FIGS. 1 and 2, the electric brake device that brakes the wheels of the automobile includes a brake caliper 11 that is supported by a knuckle or the like so as to be movable in the left-right direction in FIG. 1. Brake pads 14a and 14a are provided on opposite surfaces of the pair of back plates 12a and 12b supported so as to be able to approach and separate from each other by the guide means. . A brake piston 15 is supported on the main body 11a of the brake caliper 11 so as to be able to advance and retreat. The brake caliper 11 is pressed against the back surface of one back plate 12a by the brake piston 15 so that the brake caliper 11 is moved to the right in FIG. The arm portion 11c connected to the body portion 11a of the brake caliper 11 via the bridging portion 11b presses the back surface of the other back plate 12b, so that both brake pads 14a and 14a A braking force is generated in contact with both side surfaces. A dustproof boot 16 is mounted between the brake piston 15 and the brake caliper 11.

  The electric motor M housed in the main body 11a of the brake caliper 11 includes a plurality of stator coils 17 fixed to the inner surface of the main body 11a, and a ball bearing 18 that is rotatable around the axis L inside the stator coils 17. And a plurality of permanent magnets 20 fixed to the outer peripheral surface of the motor output shaft 19 so as to face the inner peripheral surface of the stator coils 17. A cylindrical female screw member 21 is supported inside the motor output shaft 19 by a pair of ball bearings 22 and 23 so as to be relatively rotatable. Between the male screw member 24 extending integrally on the axis L from the back surface of the brake piston 15. Are arranged with a plurality of balls 25. These female screw member 21, male screw member 24 and balls 25 ... constitute a ball screw mechanism S.

  A planetary gear mechanism P is arranged inside the main body 11 a of the brake caliper 11 so as to connect the electric motor M and the ball screw mechanism S. The planetary gear mechanism P disposed on the axis L includes a sun gear 31 fixed to the motor output shaft 19, a planetary carrier 32 fixed to the female screw member 21 of the ball screw mechanism S, and a brake caliper via the band brake device B. A ring gear 33 that can be switched between a state of being restrained by the main body portion 11a of the eleventh body and a state of being released from the restraint, and a plurality of gears that are supported by the planetary carrier 32 via pinion shafts 34 and are simultaneously meshed with the sun gear 31 and the ring gear 33. Of pinions 35. Between the planetary carrier 32 and the inner surface of the main body 11a, a thrust bearing 36 for supporting a braking reaction force that the brake piston 15 receives from the brake disk 13 is disposed.

  The band brake device B includes a brake band 37 disposed on the inner periphery of the main body 11 a so as to surround the outer periphery of the ring gear 33, and one end of the brake band 37 fixed to the main body 11 a and a movable brake band 37. A return spring 38 is disposed between the other end portion of the first and second ends. Then, by pressing the other end portion of the brake band 37 with an actuator 39 such as a solenoid provided outside the brake caliper 11, the ring gear 33 can be tightened and restrained so as not to rotate (see FIG. 3).

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  During normal braking where high responsiveness is not required, the band brake device B is in the operating position shown in FIG. 3 and restrains the ring gear 33. When the electric motor M is driven in the forward direction, the rotation of the motor output shaft 19 is caused to rotate by the planetary gear mechanism. Since the ring gear 33 is input to the sun gear 31 of the P and is restrained so as not to be rotated by the band brake device B, the rotation of the sun gear 31 is transferred to the female screw member 21 of the ball screw mechanism S via the pinion 35 and the planetary carrier 32. Communicated. When the female screw member 21 rotates, the male screw engaged with the ball 25... Moves forward together with the brake piston 15, and the brake piston 15 abuts the brake pads 14 a and 14 b against the brake disk 13 to generate a braking force. To do. When the electric motor M is driven in reverse, the brake piston 15 moves backward, the brake pads 14a and 14b are separated from the brake disc 13, and the braking force is released.

  By the way, when the braking force is controlled by rotating the electric motor M forward or backward as described above, sufficient responsiveness cannot be obtained due to the inertia of the electric motor M trying to rotate in one direction, and the tendency to lock. It is difficult to exhibit the function of an anti-lock brake that shortens the braking distance by increasing or decreasing the braking force of the wheel at a short cycle.

  Therefore, in the present embodiment, the motor M is continuously driven to rotate forward at the time of anti-lock brake control, and when the wheel is about to be locked, the brake band 37 is loosened by the actuator 39 of the band brake device B and the restraint of the ring gear 33 is released. As a result, the ring gear 33 is idled so that the driving force of the electric motor M is not transmitted to the brake piston 15, and the brake piston 15 is retracted by the reaction force received by the brake pads 14a and 14b from the brake disc 13, whereby the braking force Is weakened to avoid wheel lock.

  When the wheel speed is increased again in this way, the brake band 37 is tightened by the actuator 39 of the band brake device B to restrain the ring gear 33. Then, the brake piston 15 moves forward again by the driving force of the electric motor M to increase the braking force. By repeating this alternately, the maximum braking force can be obtained while avoiding the locking of the wheels.

  As described above, since the braking force can be increased or decreased while rotating the electric motor M in one direction, it is not necessary to alternately reverse the electric motor M against the inertia. The response of the braking force can be improved. Further, by transmitting the output of the planetary gear mechanism P to the brake piston 15 via the ball screw mechanism S, the rotation of the planetary carrier 32 can be efficiently converted into the reciprocating motion of the brake piston 15.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, among the three elements of the planetary gear mechanism P, the sun gear 31 is connected to the electric motor M, the planetary carrier 32 is connected to the brake piston 15, and the ring gear 33 is connected to the band brake device B. The sun gear 31, the planetary carrier 32, and the ring gear 33 can be connected to any of the electric motor M, the brake piston 15, and the band brake device B, thereby increasing the degree of freedom in layout.

  The driving force transmission control means is not limited to the band brake device B of the embodiment, and other types of brake mechanisms, clutch mechanisms, ratchet mechanisms, and the like can be employed.

Cross section of electric brake device 2-2 sectional view of FIG. Action explanatory diagram corresponding to FIG.

Explanation of symbols

13 Brake disc (braking member)
15 Brake piston (braking member)
31 Sungear (first element)
32 Planetary carrier (second element)
33 Ring gear (third element)
B Band brake device (drive force transmission control means)
M Electric motor P Planetary gear mechanism (driving force transmission mechanism)
S Ball screw mechanism

Claims (3)

A braked member (13) that rotates with the wheel;
A braking member (15) for braking the braked member (13);
An electric motor (M) capable of normal rotation and reverse rotation;
The electric motor (M) and the braking member (15) are connected, and the braking member (15) is brought close to the braked member (13) by the normal rotation of the electric motor (M), and the braking is performed by the reverse rotation of the electric motor (M). A driving force transmission mechanism (P) for separating the member (15) from the braked member (13);
Driving force transmission control means (B) for permitting and prohibiting driving force transmission of the driving force transmission mechanism (P);
By prohibiting the driving force transmission of the driving force transmission mechanism (P) by the driving force transmission control means (B) during the forward rotation of the electric motor (M), the reaction force from the braked member (13) An electric brake device characterized in that the braking member (15) is separated from the braked member (13).   The driving force transmission mechanism (P) is a planetary gear mechanism (P) having three elements of a sun gear (31), a planetary carrier (32), and a ring gear (33), and is a first element among the three elements. (31) is connected to the electric motor (M), the second element (32) is connected to the braking member (15), and the third element (33) is connected to the driving force transmission control means (B). The electric brake device according to claim 1, wherein rotation is permitted or prohibited. The electric brake device according to claim 2, characterized in that the second element (32) is connected to the braking member (15) via a ball screw mechanism (S).