JP2021059239A - Electric brake - Google Patents

Abstract

To make foreign matter difficult to enter at least between a friction pad and a pressing member of an electric actuator while suppressing dragging.SOLUTION: In this electric brake, for example, a retreat allowing portion is provided between a friction pad and a pressing member. As a result, it is possible to make foreign matter and the like difficult to enter a gap between the friction pad and the pressing member. Further, even if force in a retreating direction is applied to the friction pad due to runout of a disc rotor or the like, the retreat allowing portion allows the friction pad to retreat relative to the pressing member. As a result, the generation of axial force is suppressed, and dragging can be suppressed.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electric brake provided with an electric actuator.

In the electric brake described in Patent Document 1, when the vehicle is stopped or the outside air temperature is lower than the set temperature, the electric actuator is driven and the clearance between the friction pad and the disc rotor is 0. Be made. As a result, it is possible to prevent snow from entering between the friction pad and the disc rotor, and to prevent the water existing between the friction pad and the disc rotor from freezing, and to suppress rust on the disc rotor. As a result, it is possible to suppress a decrease in the effectiveness of the electric brake.

Japanese Unexamined Patent Publication No. 2001-260866

An object of the present invention is to prevent foreign matter from entering at least between the friction pad and the pressing member of the electric actuator while suppressing dragging.

Means and effects to solve problems

In the electric brake according to the present invention, at least one retreat allowance portion is provided between the friction pad and the output member of the electric actuator. The retreat allowance can be provided between two adjacent members between the friction pad and the output member, but at least one of a plurality of members located between the friction pad and the output member. It can also be a setback allowance. The retreat allowance portion can be provided, for example, in one or more of the space between the friction pad and the pressing member, the space between the pressing member and the output member, and the like.

For example, when a retreat allowable portion is provided between the friction pad and the pressing member, it is possible to prevent foreign matter or the like from entering the gap between the friction pad and the pressing member. Further, even if a force in the retreating direction is applied to the friction pad due to the runout of the disc rotor during traveling, the retreating allowance portion allows the friction pad to retreat relative to the pressing member. As a result, the generation of axial force is suppressed, and dragging can be suppressed. Further, since the retreat allowance portion is provided between the friction pad and the pressing member, the gap between the friction pad and the disc rotor can be made zero. In that case, it is possible to suppress the intrusion of foreign matter or the like between the friction pad and the disc rotor.

It is sectional drawing which shows the main part of the electric brake which concerns on Example 1 of this invention. It is sectional drawing of the electric actuator of the said electric brake. It is a figure which shows the axial force acting in the non-operating state of the electric brake. It is sectional drawing which shows the main part of the electric brake which concerns on Example 2 of this invention. It is sectional drawing which shows the main part of the electric brake which concerns on Example 3 of this invention. It is sectional drawing which shows the main part of the electric brake which concerns on Example 4 of this invention. It is sectional drawing which shows the main part of the electric brake which concerns on Example 5 of this invention. It is a figure which shows the change of the axial force at the time of releasing the electric brake.

Embodiment of the invention

An electric brake according to an embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the electric brake 8 is an electric disc brake, and (a) a disc rotor (hereinafter, simply abbreviated as a rotor) 30 as a brake rotating body that can rotate integrally with a wheel, (b). It includes a pair of friction pads 32, 34, which are held by a mounting bracket (not shown) and are located on both sides of the rotor 30, (c) a pressing device 36, and the like. The pressing device 36 straddles the rotor 30 and is held by the mounting bracket so as to be movable in a direction parallel to the rotation axis of the rotor 30. (Ii) The electric actuator 42 held by the caliper 40, (iii). ) Includes a pressing member 46 and the like facing the friction pad 32.

The friction pads 32 and 34 include friction engaging members 32a and 34a that can be engaged with the rotor 30, and backup plates 32r and 34r as holding bodies that hold the friction engaging members 32a and 34a, respectively.

As shown in FIG. 2, the electric actuator 42 has (a) a housing 44, (b) a drive source having an electric motor 48 and a speed reducer 50, and (c) an axis of the output member 54 for rotating the output shaft 70 of the drive source. The output of the electric actuator 42 includes a motion conversion mechanism 52 and the like that convert the linear movement in the direction (the reference numeral L indicates an axis. The axis L is the axis of the electric actuator 42 and is parallel to the rotation axis of the rotor 10). The pressing member 46 is moved in the axial direction by linearly moving the member 54 in the axial direction.

The pressing member 46 is held in the housing 44 so as to be movable in the axial direction and non-rotatable, and the front surface thereof is positioned so as to face the friction pad 32.

The electric motor 48 includes a plurality of coils 60 constituting the stator, a rotary drive shaft 62 having a generally hollow cylindrical shape, and the like. The rotation drive shaft 62 is held in the housing 44 via a bearing 63 so as to be rotatable around the axis L and immovable in the axial direction. Further, the rotation of the rotation drive shaft 62 is input to the speed reducer 50.

The speed reducer 50 is of a planetary gear type, and meshes with both the sun gear 64 that can rotate integrally with the rotary drive shaft 62, the ring gear 66 fixed to the housing 44, and the sun gear 64 and the ring gear 66. A plurality of planetary gears 68 revolving around the sun gear 64 (FIG. 3 shows one of the plurality of planetary gears 68). A carrier 72 holding a plurality of planetary gears 68 is connected to an output shaft 70 of the speed reducer 50, in other words, an output shaft 70 of a drive source. Specifically, the carrier 72 is integrally rotatably provided on the output shaft 70, and the planetary gear 68 is rotatably attached to the carrier 72. The output shaft 70 is rotated along the axis L as the planetary gear 68 revolves. It is rotated around. The speed reducer 50 reduces the rotational speed of the rotary drive shaft 62 and outputs the output shaft 70, and the rotary drive force of the rotary drive shaft 62 is boosted and output.

The output shaft 70 extends in the axial direction and is held in the housing 44 so as to be rotatable and immovable in the axial direction. Further, the output member 54 is located on the inner peripheral side of the rotation drive shaft 62 so as to be relatively movable and relatively rotatable in the axial direction, and is held in the housing 44 so as to be relatively non-rotatable and relatively movable in the axial direction. .. A female screw portion 54s extending in the axial direction is formed in the central portion of the output member 54.
A carrier 72 is attached to the rear portion of the output shaft 70, and a male screw portion 70s is formed on the outer peripheral portion of the front portion. The male threaded portion 70s is screwed into the female threaded portion 54s of the output member 54. As a result, the rotation of the output shaft 70 is converted into a linear movement of the output member 54 in the axial direction. In this embodiment, the motion conversion mechanism 52, which is a screw mechanism, is configured by the male screw portion 70s of the output shaft 70, the female screw portion 46s of the output member 54, and the like.

The forward rotation of the electric motor 48 advances the output member 54 and advances the pressing member 46. The pressing member 46 and the caliper 40 press the pair of friction pads 32 and 34 against the rotor 30, and the rotation of the wheel 6 is suppressed. The electric brake 8 is operated, and a braking force corresponding to the pressing force applied to the rotor 30 is applied to the wheels 6.
Further, the rotation of the electric motor 48 in the opposite direction causes the output member 54 to be retracted and the pressing member 46 to be retracted.

The return spring 90 is provided between the rear portion of the output shaft 70 and the housing 44. The return spring 90 applies a spring force (hereinafter, referred to as a spring force in the backward rotation direction) in a direction for rotating the output shaft 70 in the backward rotation direction of the output member 54 to the output shaft 70. The return spring 90 allows the output shaft 70 to rotate in the retracting direction and retracts the output member 54.

The electric brake 8 includes a motor ECU 100 that controls an electric motor 48. The motor ECU 100 is mainly composed of a computer, and includes an execution unit, a storage unit, an input / output unit, and the like, which are not shown.

A resolver 110 that detects the rotation angle of the electric motor 48, an axial force sensor 112 that detects an axial force that is an axial force applied to the output member 54, and the like are connected to the input / output section of the motor ECU 100, and are electrically driven. A drive circuit (not shown) of the motor 48 is connected.
The axial force sensor 112 detects the axial force applied to the support plate 120 by the thrust bearing 122 provided between the output shaft 70 and the support plate 120 of the housing 44. Therefore, the axial force sensor 122 can detect the axial force applied to the output member 54 via the pressing member 46, that is, the reaction force of the pressing force, which is the force with which the friction pads 32 and 34 push the rotor 30.

When the electric brake 8 is operated, the motor ECU 100 controls the electric motor 48 so that the actual axial force detected by the axial force sensor 112 approaches the target axial force supplied from the brake ECU (not shown). The electric motor 48 is controlled so that the stroke of the output member 54 or the pressing member 46 determined by the actual rotation angle detected by the resolver 110 approaches the target stroke supplied from the brake ECU.
When the electric brake 8 is released, the output member 54 is retracted until the actual axial force detected by the axial force sensor 112 becomes zero.

In the conventional electric brake 8, a gap is provided between the friction engaging member 32a and the rotor 30 and between the pressing member 46 and the backup plate 32r in the non-operating state of the electric brake 8. It's normal.
When the pressing device 36 includes a hydraulic cylinder, the piston of the hydraulic cylinder is retracted even if a force in the retracting direction is applied to the friction pad 32 due to the runout of the rotor 30 during traveling. , Axial force due to runout of the rotor 30 is unlikely to occur, and dragging is unlikely to occur.
On the other hand, in the electric brake 8 according to the present embodiment, the pressing device 36 includes the electric actuator 42, and the male screw portion 46s and the female screw portion 70s included in the motion conversion mechanism 52 are trapezoidal screw portions. The reverse efficiency {efficiency when rotating the output shaft 70 by retreating the pressing member 46 (output member 54)} is smaller than the positive efficiency (efficiency when moving the output member 46 by rotating the output shaft 70). .. Therefore, even if a force in the retreating direction is applied to the friction pad 32 and a force in the retreating direction is applied to the pressing member 46, it becomes difficult to rotate the output shaft 70 in the retreating direction, and the output member 54 can be retracted. It becomes difficult, and there are problems such as dragging. In order to solve this problem, a gap is provided between the friction engaging member 32a and the rotor 30 and at least one of the backup plate 32r and the pressing member 46.

However, the electric brake 8 is caused by foreign matter entering the gap between the friction engaging member 32a and the rotor 30 or the gap between the backup plate 32r and the pressing member 46, or the snow entering the gap freezes. Performance may deteriorate.

Therefore, in the electric brake 8 according to the present embodiment, as shown in FIG. 1, a retreat allowable portion 130 is provided between the backup plate 32r and the pressing member 46. The retreat permitting portion 130 allows the backup plate 32r as a member on the friction pad side to retreat relative to the pressing member 46 as a member on the output member side, and is provided on the rear surface of the backup plate 32r and rearward. It includes an annular convex portion 132 that projects toward it, an annular groove portion 134 provided on the front surface of the pressing member 46, and a spring 136 provided between the backup plate 32r and the pressing member 46.

The annular convex portion 132 and the annular groove portion 134 have substantially the same size, and the radial width of the groove portion 134 is larger than the radial width of the convex portion 132. Therefore, the annular convex portion 132 can be inserted into the annular groove portion 134 with a gap. The spring 136 extends in the axial direction, one end of which is attached to the bottom of the groove 134, and the other end of which is attached to the rear surface 132f of the convex portion 132.

In this way, the retreat allowable portion 130 including the annular convex portion 132 and the like is provided between the backup plate 32r and the pressing member 46. As a result, it is possible to prevent foreign matter and the like from entering between the backup plate 32r (friction pad) and the pressing member 46.
Further, when a force in the backward direction acts on the friction engaging member 32a due to the runout of the rotor 30 during traveling in the non-operating state of the electric brake 8, the elastic deformation of the spring 136 causes the friction pad 32 to be relative to the pressing member 46. Retreat is allowed. As a result, it is possible to suppress the generated axial force and make it difficult for dragging to occur.
Further, as described above, when the electric brake 8 is released, the output member 54 is retracted until the axial force detected by the axial force sensor 112 becomes 0, so that the electric brake 8 is in the non-operating state. , The spring 136 is in a state where no elastic force is generated. Therefore, as shown in FIG. 3, the restoring force (force in the forward direction) Ff of the spring 136 is applied to the friction pad 32 due to the backward force Fb acting on the friction pad 32, but the restoring force. By Ff, the friction pad 32 is only advanced to a position where the axial force becomes 0 (the position before the force Fb is applied). As a result, it is possible to further suppress the axial force applied to the friction pad 32, and it is possible to further reduce dragging.

Further, since the retreat allowable portion 130 is provided between the backup plate 32r and the pressing member 46, the gap between the friction engaging member 32a and the rotor 30 can be set to 0 in the non-operating state of the electric brake 8. it can. In that case, it is possible to suppress the intrusion of foreign matter or the like between the friction engaging member 32a (friction pad 32) and the rotor 30. The same applies to the following examples.

As shown in FIG. 4, in the electric brake 148, a stretchable cover 150 is provided between the pressing member 46 and the main body 44. The cover 150 is made of an elastic material such as rubber, and is held by the pressing member 46 and the main body 44. According to the cover 150, the relative movement of the pressing member 46 with respect to the main body 44 is allowed, and foreign matter or the like can be prevented from entering between them.
In the electric brake 148 according to the present embodiment, the tubular portion 152 of the cover 150 is extended in the axial direction so that it can come into contact with the rear surface of the backup plate 32r. In other words, the axial length of the tubular portion 152 is set to be the length corresponding to the gap between the rear surface of the backup plate 32r and the front surface of the pressing member 46 in the non-operating state of the electric brake 148. Reference numeral 152 denotes a state in which no elastic force is generated in the non-operating state of the electric brake 148. Then, the tubular portion 152 of the cover 150 corresponds to the retreat allowable portion that allows the relative retreat of the backup plate 32r with respect to the pressing member 46.

In this way, even if a force in the backward direction acts on the friction engaging member 32a due to the runout of the rotor 30 in the non-operating state of the electric brake 148 due to the elastic deformation of the tubular portion of the cover 150, the backup plate Since the relative retreat of the 32r with respect to the pressing member 46 is allowed, dragging can be satisfactorily suppressed. Further, the shaft portion 152 makes it difficult for foreign matter or the like to enter between the backup plate 32r (friction pad 32) and the pressing member 46.

In the electric brake 178 according to the present embodiment, as shown in FIG. 5, a tubular elastic member 180 is provided between the friction engaging member 32a and the backup plate 32r. One end of the elastic member 180 in the axial direction is fitted into an annular groove 182 formed on the rear surface of the friction engaging member 32a, and the other end protrudes from the groove 182 and hits the front surface of the backup plate 32r. It is possible to contact. In the non-operating state of the electric brake 178, the other end of the elastic member 180 is in contact with the backup plate 32r, but in this state, the elastic member 180 is in a state of not generating an elastic force. Then, in the electric brake 178, the elastic member 180 corresponds to a retreat allowable portion that allows the relative retreat of the friction engaging member 32a as a member on the friction pad side with respect to the backup plate 32r as a member on the output member side. ..

As described above, even if a force in the backward direction acts on the friction engaging member 32a due to the runout of the rotor 30 or the like in the non-operating state of the electric brake 178, the friction engaging member due to the elastic deformation of the elastic member 180. Since the relative retreat of the 32a with respect to the backup plate 32r is allowed, the axial force can be suppressed and the dragging can be satisfactorily suppressed.
Further, since the retreat allowance portion 180 is provided between the friction engaging member 32a and the backup plate 32r, the gap between the backup plate 32r and the pressing member 46 is set to 0 in the non-operating state of the electric brake 178. Can be done. As a result, it is possible to prevent foreign matter and the like from entering between the backup plate 32r (friction pad) and the pressing member 46.
An annular groove may be provided on the front surface of the backup plate 32r so that the elastic member 180 can be fitted.

In the electric brake 198 according to this embodiment, as shown in FIG. 6, it is assumed that the backup plate 200 is manufactured by an elastic member. The backup plate 200 is in a state in which no elastic force is generated in the non-operating state of the electric brake 198.
The backup plate 200 corresponds to a retreat permitting portion that allows the friction engaging member 32a as a member on the friction pad side to retreat relative to the pressing member 46 as a member on the output member side.

In this embodiment, even if a force in the backward direction is applied to the friction engaging member 32a due to the runout of the rotor 30 in the non-operating state of the electric brake 198 due to the elastic deformation of the backup plate 200, the friction engaging member Since the relative retreat of the 32a with respect to the pressing member 46 is allowed, it is possible to prevent dragging from occurring. Further, in the non-operating state of the electric brake 198, the gap between the backup plate 200 and the pressing member 46 can be set to 0. As a result, it is possible to prevent foreign matter or the like from entering between the backup plate 200 (friction pad) and the pressing member 46.

In the electric brake 248 according to the present embodiment, as shown in FIG. 7, a spring 254 elastically deformable in the axial direction is provided between the output member 250 and the pressing member 252. Further, the output member 250 and the pressing member 252 are engaged in a state in which the pressing member 252 can be retracted as the output member 250 retracts. In other words, the pressing member 252 is provided with a ring-shaped member 260 protruding inward in the radial direction, the output member 250 is provided with a flange 262 protruding outward in the radial direction, and the flange 262 is the ring-shaped member 260. Located in front. The spring 254 corresponds to a retreat permitting portion that allows the pressing member 252 as a member on the friction pad side to retreat relative to the output member 250 as a member on the output member side. Further, in the electric brake 248 according to the present embodiment, the state shown in the drawing, that is, the state in which the spring 254 does not generate an elastic force in the state where the flange 262 of the output member 250 is in contact with the ring-shaped member 260 of the pressing member 252. Will be done.

When the electric brake 248 is activated, the output member 250 is advanced against the elastic force of the spring 254. When the output member 250 comes into contact with the pressing member 252, the pressing member 252 is then advanced as the output member 250 advances. The pair of friction pads 32, 34 are pressed against the rotor 30 to activate the electric brake 248.

When the electric brake 248 is released, the output member 250 is retracted, and the pressing member 252 is retracted by the restoring force of the friction engaging member 32a, the restoring force of the return spring 90, and the like. During this period, as shown in FIG. 8, the decreasing gradient of the axial force with respect to the increase in the backward stroke of the output member 250 is large. Then, when the restoring force of the friction engaging member 32a applied to the pressing member 252 becomes small, the elastic force of the spring 254 is mainly applied to the output member 250. The output member 250 is retracted relative to the pressing member 252. During this period, the decreasing gradient of the axial force with respect to the increase in the backward stroke of the output member 250 becomes smaller. The output member 250 is retracted until the axial force detected by the axial force sensor 112 becomes zero. Due to the relative retreat of the output member 250 with respect to the pressing member 252, the flange 262 abuts on the ring-shaped member 260 and the axial force often becomes 0, but the shaft is in a state where the flange 262 abuts on the ring-shaped member 260. When the force is larger than 0, the pressing member 252 is retracted as the output member 250 retracts until the axial force becomes 0.

Then, in the non-operating state of the electric brake 248, even if a force in the retreating direction is applied to the friction engaging member 32a due to the runout of the rotor 30, the retreating of the pressing member 252 with respect to the output member 250 springs. Allowed by 254. Therefore, it is possible to suppress dragging caused by runout of the rotor 30 in the non-operating state of the electric brake 248. Further, in the electric brake 248 according to the present embodiment, since the spring 254 is provided between the pressing member 252 and the output member 250, between the backup plate 32r and the pressing member 252 in the non-operating state of the electric brake 248. The gap between the two can be set to zero. Therefore, it is possible to prevent foreign matter and the like from entering between the backup plate 32r (friction pad) and the pressing member 252.

In addition to the above-described embodiments, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

8,148,178,198,248: Electric brake 32a: Friction engaging member 32r: Backup plate 46: Pressing member 130: Retreat allowable part 136: Spring 150: Cover 152: Tube part 180: Elastic member 200: Backup plate 252 : Pressing member 250: Output member 254: Spring

Claimable invention

(1) A pair of friction pads located on both sides of a brake rotating body that can rotate integrally with the wheel,
An electric brake including a pressing device including an electric actuator, in which the pressing member is advanced by advancing the output member of the electric actuator, and the pair of friction pads are pressed against the brake rotating body to suppress the rotation of the wheels. And
The electric brake is provided between the friction pad and the output member, and includes at least one retreat permitting portion that allows the member on the friction pad side to retreat relative to the member on the output member side. ..
(2) Each of the pair of friction pads includes a friction engaging member capable of frictionally engaging with the brake rotating body and a holding body holding the friction engaging member.
The electric brake according to item (1), wherein one of the at least one retreat allowable portion is provided between the friction engaging member and the holding body.
(3) The electric brake according to item (1) or (2), wherein one of the at least one retreat allowable part is provided between the friction pad and the pressing member.
For example, a retreat allowance portion can be provided between the holding body and the pressing member.
(4) The electric brake according to any one of items (1) to (3), wherein one of the at least one retreat allowable part is provided between the pressing member and the output member.
(5) Each of the pair of friction pads includes a friction engaging member capable of frictionally engaging with the brake rotating body and a holding body holding the friction engaging member.
The electric brake according to any one of items (1) to (4), wherein the holding body is one of the at least one retreat allowable part.
In the electric brake described in this section, the holding body allows the friction engaging member to move backward relative to the pressing member.
(6) The electric brake according to any one of items (1) to (5), wherein one of the at least one retreat allowable part includes an elastic member.
The elastic member corresponds to a spring, rubber, or the like.
(7) Items (1), (2), (4) to (6), wherein the gap between the friction pad and the front surface of the pressing member is 0 in the non-operating state of the electric brake. The electric brake described in any one of.
(8) The item according to any one of (1) to (7), wherein the gap between the friction pad and the friction surface of the rotating brake body is 0 in the non-operating state of the electric brake. Electric brake.
(9) The electric brake includes an actuator control unit that retracts the output member by controlling the electric actuator.
The electric brake according to any one of items (1) to (8), wherein the actuator control unit retracts the output member until the axial force applied to the output member becomes zero.
In the above embodiment, the actuator control unit is configured by the motor ECU 100, the axial force sensor 112, and the like.

Claims (1)

A pair of friction pads located on both sides of the brake rotating body that can rotate integrally with the wheel,
An electric brake including a pressing device including an electric actuator, in which the pressing member is advanced by advancing the output member of the electric actuator, and the pair of friction pads are pressed against the brake rotating body to suppress the rotation of the wheels. And
The electric brake is provided between the friction pad and the output member, and includes at least one retreat permitting portion that allows the member on the friction pad side to retreat relative to the member on the output member side. ..

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