The present invention relates to a disk brake device used in a vehicle or the like to generate a braking force using friction.
A disk brake device is used widely in vehicles or the like and configured to press a friction pad against a rotor which rotates together with a wheel in response to a stepping operation performed on a brake pedal, for example, to generate a frictional force and thus brake the rotation of the rotor. An example of conventionally well known disk brake devices uses a hydraulic force to press a friction pad against a rotor. A disk brake device of this type is configured to actuate a piston using a hydraulic force to move a friction pad which faces a rotor, in the direction perpendicular to the rotor and thus press the friction pad against the rotor. In a hydraulically driven disk brake device, units such as a booster which amplifies an operational force applied to a brake pedal and a master cylinder which converts the operational force amplified by the booster to a hydraulic pressure are needed, which complicates the device configuration.
In view of this, there has recently been developed a disk brake device of a type which drives an electric motor to rotate in response to an operation performed on a brake pedal and presses a friction pad against a rotor using the resulting rotational driving force to generate a braking force (see, e.g., Patent Document 1). Such a configuration as disclosed in Patent Document 1 is advantageous in that, by omitting a booster, a master cylinder, and the like, a simple disk brake device can be configured. The applicant has recently developed a disk brake device which uses an electric motor, in which a friction pad is moved relative to a base plate, which serves as the reference, in the direction perpendicular to a rotor while moving the friction pad to slide in the rotating direction of the rotor when the friction pad is pressed against the rotor to automatically amplify a pressing force with which the friction pad is pressed against the rotor using a wedge effect.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2008-516169 (A) based on PCT International Application No. PCT/JP2012/004374
For the disk brake device which uses the wedge effect to precisely control the pressing force of the friction pad, it is particularly important to precisely control slide movement of the friction pad in the rotating direction. Because the friction pad is moved to slide with reference to the base plate, it is necessary to restrict movement of the base plate, which serves as the reference, in the rotating direction. On the other hand, when the friction pad is abraded, it is also necessary to integrally move the friction pad and the base plate closer to the braking surface (for adjustment) in order to keep the gap between the friction pad and the braking surface at a constant distance. Thus, it has been difficult to permit movement of the base plate in the direction which brings the base plate closer to the braking surface while restricting movement of the base plate in the rotating direction.
The present invention has been achieved in view of problems as described above and an object of the present invention is to provide a disk brake device configured to permit movement of a base plate in the direction which brings the base plate closer to a braking surface while restricting movement of the base plate in the rotating direction.
To attain the object described above, a disk brake device according to the present invention includes: a rotor having a disk-shaped braking surface and coupled to a rotating body to be braked to rotate; a carrier attached to a support member (e.g. axle shaft 2 in an embodiment) which rotatably supports the rotating body and disposed to face the braking surface of the rotor; a caliper attached to the carrier to be movable in a direction perpendicular to the braking surface; a friction pad (e.g. inner pad 43 in the embodiment) disposed to face the braking surface of the rotor; and a braking operation mechanism attached to the caliper to be caused to perform an operation of pressing the friction pad against the braking surface, the braking operation mechanism including a base member (e.g. base plate 35 in the embodiment) held by the caliper, a slide member (e.g. wedge plate 37 in the embodiment) disposed to face the base member and holding the friction pad, and a slide member movement mechanism (e.g. cam member 27, rollers 36, and cam drive unit 100 in the embodiment) provided between the base member and the slide member to move the slide member in the direction perpendicular to the braking surface while moving the slide member to slide relative to the base member in a rotating direction of the rotor in parallel to the braking surface, the slide member and the friction pad held thereby being moved by the slide member movement mechanism in the rotating direction of the rotor and the direction perpendicular to the braking surface so that the friction pad is pressed against the braking surface to brake rotation of the rotor, the carrier including a pair of rotating-direction movement restricting portions (e.g. inner-side rotating-direction movement restricting portions 16 in the embodiment) which hold the base member therebetween at both ends in the rotating direction of the rotor and hold the base member with movement thereof in the rotating direction restricted, the disk brake device further including a pressing member (e.g. pressing positioning member 80 in the embodiment) inserted into one of gaps between the pair of rotating-direction movement restricting portions and both ends of the base member so as to be attached to the base member, and the pressing member being configured to press the base member in a direction away from the rotating-direction movement restricting portion in the one of the gaps, cause an end portion of the base member to abut against the rotating-direction movement restricting portion forming the other of the gaps, and position the base member relative to the carrier in the rotating direction, thereby permitting the base member to move in the direction perpendicular to the braking surface with the base member kept positioned in the rotating direction.
In the disk brake device described above, it is preferable that the pressing member includes an elastically deformable portion (e.g. plate-shaped main body portion 81 in the embodiment) formed to be elastically deformable; and the elastically deformable portion is elastically deformed when inserted into one of the gaps, thereby pressing the base member in the direction away from the rotating-direction movement restricting portion.
In addition, it is preferable that the pressing member includes an engagement portion which is engaged with the base member when inserted into one of the gaps.
The disk brake device according to the present invention includes a pressing member inserted into one of gaps between the pair of rotating-direction movement restricting portions and both ends of the base member so as to be attached to the base member. Therefore, the pressing member can press the base member in the rotating direction to cause the base member to abut against the rotating-direction movement restricting portion. Thus, it is possible to achieve a configuration which permits movement of the base member in the direction which brings the base member closer to the braking surface while restricting movement of the base member in the rotating direction.
In the disk brake device described above, it is preferable that the pressing member includes an elastically deformable portion formed to be elastically deformable. When the elastically deformable portion is inserted into the gap between the rotating-direction movement restricting portion and the base member, the base member can be caused by the spring force of the elastically deformable portion to elastically abut against the rotating-direction movement restricting portion. Therefore, even if an external force is applied to the base member, it is possible to receive and absorb such an external force and maintain a state in which the base member abuts against the rotating-direction movement restricting portion.
In addition, it is preferable that the pressing member includes an engagement portion which is engaged with the base member. With such a configuration, the pressing member can be inserted into the gap between the rotating-direction movement restricting portion and the base member to integrally attach the pressing member to the base member. Therefore, it is possible to prevent the pressing member from slipping off from the gap between the rotating-direction movement restricting portion and the base member.
Referring to the drawings, a description will be given below of an embodiment of the present invention.
As shown in
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As shown in
The caliper 7 is attached to the carrier 5 using a slide pin 8, and movable to slide in the axial direction of the rotor 4. Therefore, the caliper assembly 10 (the caliper 7, and the braking unit 11, the adjustment units 30, and the cam drive unit 100 disposed inside and outside the caliper 7) is integrally movable to slide in the axial direction of the rotor 4.
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Coupling clips 60 shown in
The procedure for mounting the inner pad 43 to the wedge plate 37 using the coupling clips 60 is described. As shown in
After the inner pad 43 is mounted to the wedge plate 37, as shown in
As shown in
The adjustment units 30 are disposed between an adjustment case 34 and the inner housing 6a. The adjustment units 30 can perform the gap adjustment by rotating the adjustor tubular body 33 through the adjusting drive gear 38 and pushing out the adjustor main body portion 32 toward the outer side to move the inner pad 43 closer to the braking surface 4a of the rotor 4 via the braking unit 11.
The braking unit 11 is provided on the outer side of the adjustment case 34. The base plate 35 is placed on the inner-side radial-direction movement restricting portions 17 of the carrier 5, and held between the inner-side rotating-direction movement restricting portions 16 of the carrier 5. As shown in
As shown in
The electric motor 110 includes a motor main body portion 111 which receives supply of electric power to generate a rotational driving force, and a motor output shaft 112 which outputs the rotational driving force generated by the motor main body portion 111. A rotation angle sensor 113 (e.g. an encoder) which detects the rotation angle of the electric motor 110 is built in the electric motor 110. In the embodiment, the electric motor 110 is attached to the outside of the inner housing 6a, which ensures the degree of freedom of the arrangement of the electric motor 110 and also supports an increase in size of the electric motor 110.
The speed reducer 120 includes a first input shaft 121 connected to the motor output shaft 112, a first planetary gear unit 122 which includes a sun gear, planetary gears, a ring gear, and so forth (not shown), a second input shaft 123 to which the rotational driving force which has been reduced in speed by the first planetary gear unit 122 is input, and a second planetary gear unit 124 which includes a sun gear, planetary gears, a ring gear, and so forth (not shown). In the speed reducer 120, the rotational driving force of the motor output shaft 112 is first reduced in speed by the first planetary gear unit 122, and further reduced in speed by the second planetary gear unit 124 to be output. An involute serrated shaft receiving portion 154 such as that shown in
As shown in
The gear unit 140 includes an input-side spur gear 150, an output-side spur gear 160 engaged with the input-side spur gear 150, and a gear holding frame 141 which rotatably holds the spur gears 150 and 160.
As shown in
The gear holding frame 141 rotatably holds the input-side spur gear 150 and the output-side spur gear 160 as engaged therewith. The gear holding frame 141 includes an attachment projection 142 which projects toward the outer side. As shown in
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Thus far, the description has been given of the overall configuration of the disk brake device 1. In the following, referring to
First, in Step S10 shown in
In subsequent Step S40, the controller 91 determines whether or not the rotating direction of the rotor 4 input in Step S10 is the forward side f. When the rotating direction of the rotor 4 is the forward side f, the controller 91 outputs a drive signal to the electric motor 110 so as to move the wedge plate 37 to slide toward the forward side f (Step S51). When the electric motor 110 is driven to rotate on the basis of the input drive signal, the rotational driving force of the electric motor 110 is reduced in speed by the speed reducer 120, and thereafter transmitted to the gear unit 140 via the driving force transmission shaft 130. The rotational driving force transmitted to the gear unit 140 is transmitted from the input-side spur gear 150 to the output-side spur gear 160, and further from the output-side spur gear 160 to the cam drive shaft member 170, which drives the cam member 27 to rotate in response to the rotational driving of the electric motor 110. When the cam member 27 is driven to rotate, the cam-side abutment surfaces 27c of the cam member 27 press the rack-side abutment surfaces 37d of the wedge plate 37 to move the wedge plate 37 to slide in the rotating direction (which is the forward side f in this case) of the cam member 27.
By thus using the configuration which causes the cam-side abutment surfaces 27c each formed in the involute shape to abut on the rack-side abutment surfaces 37d and move the wedge plate 37 to slide, it is possible to inhibit slip occurring between the cam-side abutment surfaces 27c and the rack-side abutment surfaces 37d and efficiently convert the rotational driving force of the cam member 27 to the slide movement of the wedge plate 37.
In
On the other hand, when the rotating direction of the rotor 4 is determined as the rearward side r in Step S40, a drive signal is output from the controller 91 to the electric motor 110 so as to move the wedge plate 37 to slide toward the rearward side r (Step S52). In
The wedge plate 37 is pushed out toward the outer side while moving to slide toward the forward side f or the rearward side r in accordance with the rotation angle of the cam member 27, as a result of which the inner pad 43 is pressed against the braking surface 4a. As a result, a counterforce exerted from the braking surface 4a acts on the caliper 7 (inner housing 6a) via the inner pad 43, the shoe plate 44, the wedge plate 37, the rollers 36, the adjustment case 34, the base plate 35, and the adjustment units 30 to press the caliper 7 toward the inner side.
When the caliper 7 is pressed toward the inner side to be slid, the shoe plate 42 and the outer pad 41 are integrally pressed toward the inner side by the outer housing 6b. Consequently, the outer pad 41 is pressed against the braking surface 4a on the outer side to apply a braking force to the braking surface 4a. Each of the outer pad 41 and the inner pad 43 is thus pressed against the braking surface 4a to apply a braking force to the rotor 4.
The disk brake device 1 is configured such that, by the braking unit 11, the pressing force pressing the inner pad 43 against the braking surface 4a is automatically amplified (self-boosting is effected). The configuration will be described with reference to
As shown in
When the frictional force acting on the inner pad 43 is amplified from F×μ to (F+F′)×μ, the inner pad 43, the shoe plate 44, and the wedge plate 37 are resultantly integrally moved to slide toward the forward side f. When such components are moved to slide toward the forward side, the wedge plate 37 receives a larger counterforce from each of the rollers 36 so that the inner pad 43 is thereby pressed against the braking surface 4a with a larger pressing force. The disk brake device 1 is configured to achieve a wedge effect in which the operation in which the inner pad 43 is thus moved to slide in the forward side f by the frictional force and the operation in which the inner pad 43 is thus pressed against the braking surface 4a with a larger pressing force are repeated to cause the pressing force of the inner pad 43 to be automatically amplified.
Subsequently, the flow advances to Step S60 where it is determined in the controller 91 whether or not the pressing force of the inner pad 43 detected in the pressing force sensor 31 when the braking force acts with the outer pad 41 and the inner pad 43 pressed against the braking surfaces 4a is larger than the pressing force corresponding to the braking operation force detected in the stepping force sensor 92a.
In Step S60, when it is determined that the pressing force detected in the pressing force sensor 31 is larger than the pressing force corresponding to the brake operation force, the flow advances to Step S71. In the embodiment which assumes forward running, in Step S71, a drive signal is output from the controller 91 to the electric motor 110 so as to move the wedge plate 37 toward the rearward side to weaken the pressing force. On the other hand, when it is determined that the pressing force detected in the pressing force sensor 31 is smaller than the pressing force corresponding to the brake operation force, the flow advances to Step S72. In the embodiment, in Step S72, a drive signal is output from the controller 91 to the electric motor 110 so as to move the wedge plate 37 toward the forward side to enhance the pressing force.
By repeatedly performing Steps S60, S71, and S72, the rotational driving of the electric motor 110 is controlled so as to press the inner pad 43 against the braking surface 4a with the pressing force corresponding to the braking operation force applied to the brake pedal 92. Consequently, it is possible to cause the braking force intended by the driver to act on the rotor 4 and decelerate the vehicle.
Thus far, the description has been given of the operation of the disk brake device 1. For the disk brake device 1 to obtain the wedge effect, it is necessary to move the inner pad 43 to slide in the rotating direction when the inner pad 43 is moved in the direction perpendicular to the braking surface 4a. On the other hand, in order to press the inner pad 43 against the braking surface 4a to apply a braking force, it is necessary to restrict movement of the inner pad 43 in the rotating direction so that the inner pad 43 does not rotate together with the rotor 4 with the inner pad 43 pressed against the braking surface 4a.
With the inner pad 43 pressed against the braking surface 4a, a rotating-direction component of the braking force generated between the braking surface 4a and the inner pad 43 is transmitted to the base plate 35 via the wedge plate 37 and the rollers 36. Thus, as shown in
On the other hand, a component of the braking force generated between the braking surface 4a and the inner pad 43 in the radial direction of the rotor 4 is received with at least one of the inner pad 43, the shoe plate 44, and the wedge plate 37 abutting against the inner-side radial-direction movement restricting portions 17 of the carrier 5. With both the rotating-direction force and the radial-direction force which act on the inner pad 43 thus reliably received by the carrier 5 secured to the axle shaft 2, the disk brake device 1 can have a robust structure with an increased rigidity. With such a robust structure, a braking force corresponding to a brake operation can be precisely applied to the braking surface 4a, which improves the feel of the brake operation.
In addition, as shown in
Thus far, the description has been given of the configuration which permits the inner pad 43 to be pressed against the braking surface 4a while moving the inner pad 43 to slide in the rotating direction, and which can effectively restrict movement of the inner pad 43 in the rotating direction when a braking force is applied.
For the disk brake device 1 which uses the wedge effect to precisely control the pressing force of the inner pad 43, it is important to precisely control slide movement of the inner pad 43 in the rotating direction. Because the inner pad 43 is moved to slide with respect to the base plate 35, it is necessary to restrict movement of the base plate 35, which serves as the reference, in the rotating direction for positioning. On the other hand, because the disk brake device 1 is assembled with the base plate 35 inserted between the pair of inner-side rotating-direction movement restricting portions 16, it is necessary to provide a gap (clearance) for absorbing a processing error.
With the presence of the clearance, when the base plate 35 is disposed between the pair of inner-side rotating-direction movement restricting portions 16, a gap corresponding to the clearance is formed between the base plate 35 and the inner-side rotating-direction movement restricting portions 16. Therefore, when it is attempted to move the wedge plate 37 to slide toward the forward side by driving the cam member 27, first, the base plate 35 is moved to slide toward the rearward side by an amount corresponding to the clearance by the counterforce applied to the cam member 27. At this time, because the counterforce applied to the cam member 27 is not received, the wedge plate 37 is not moved to slide toward the forward side even if the cam member 27 is driven. When the base plate 35 is moved to slide toward the rearward side by the amount corresponding to the clearance to abut against the inner-side rotating-direction movement restricting portions 16, the wedge plate 37 is moved to slide toward the forward side in response to driving of the cam member 27 with the counterforce applied to the cam member 27 received by the inner-side rotating-direction movement restricting portions 16. If the clearance is thus provided, there is generated a delay in driving of the wedge plate 37 (inner pad 43) by an amount corresponding to the slide movement of the base plate 35 caused by the counterforce applied to the cam member 27. Such a delay in driving is generated every time the driving direction of the cam member 27 is changed in order to control the pressing force of the inner pad 43.
Thus, in the disk brake device 1, as shown in
The spring force of the plate-shaped main body portion 81 constituting the pressing positioning member 80 will be described with reference to
hen the inner pad 43 is abraded, it is necessary to bring the inner pad 43 and the base plate 35 closer to the braking surface 4a for adjustment in order to keep the gap between the inner pad 43 and the braking surface 4a at a predetermined distance. In the case where the inner pad 43 and the base plate 35 are brought closer to the braking surface 4a for adjustment, as shown in
When the pressing positioning member 80 is inserted into the gap between the base plate 35 and the inner-side rotating-direction movement restricting portion 16, the pressing positioning member 80 is attached to the base plate 35 with the engagement portions 83 engaged with the rearward-side end portion of the base plate 35. Therefore, it is possible to prevent the pressing positioning member 80 from slipping off from the gap between the base plate 35 and the inner-side rotating-direction movement restricting portion 16.
In the disk brake device 1 according to the embodiment, the pressing positioning member 80 is provided at a position at which the pressing positioning member 80 receives the counterforce F1 applied toward the rearward side, that is, inserted into the gap between the rearward-side end portion of the base plate 35 and the inner-side rotating-direction movement restricting portion 16. Therefore, there is a possibility that a gap is formed between the pair of inner-side rotating-direction movement restricting portions 16 and the base plate 35 with the plate-shaped main body portion 81 deformed by a braking force during rearward running. However, with a priority given to forward running, which is generally more frequent than rearward running, it is possible to prevent a delay in driving of the wedge plate 37 during forward running.
Thus far, the description has been given of the configuration which permits movement of the base plate 35 in the direction which brings the base plate 35 closer to the braking surface 4a while restricting movement of the base plate 35 in the rotating direction.
In order to efficiently transmit the rotational driving force of the electric motor 110 to the cam member 27, it is preferable that the electric motor 110 is configured to be disposed on the axis of the cam drive shaft 170. With this configuration, however, components of the vehicle mounted with the disk brake device 1 and the electric motor 110 may interfere with each other to restrain the arrangement space for the electric motor 110. In particular, the arrangement space for the electric motor 110 is more easily restrained as the electric motor 110 increases in size.
Thus, in the disk brake device 1, the electric motor 110 is not disposed on the axis of the cam drive shaft 170, but attached to the outer circumferential portion of the caliper 7 (inner housing 6a) such that the motor output shaft 112 is positioned on the outer circumferential side with respect to the cam drive shaft 170. With the electric motor 110 thus attached to the outer circumferential portion of the caliper 7, it is possible to increase the degree of freedom of the arrangement of the electric motor 110 while avoiding interference between components of the vehicle mounted with the disk brake device 1 and the electric motor 110.
If the electric motor 110 is attached to the outer circumferential portion of the caliper 7, a mechanism which transmits the rotational driving force of the motor output shaft 112 to the cam drive shaft 170 is necessary. The caliper 7 to which the electric motor 110 is attached is attached to the carrier 5 via the slide pin 8, and has a clearance which permits slide movement. On the other hand, the cam drive shaft 170 is positioned on the carrier 5 via the base plate 35. Therefore, there may be a case where the axis of the motor output shaft 112 (output shaft of the speed reducer 120) and the axis of the cam drive shaft 170 are tilted.
Therefore, as shown in
When the inner pad 43 is adjusted by the adjustment unit 30, the cam member 27 and the cam drive shaft 170 are integrally pushed out toward the outer side. On the other hand, the gear unit 140 which transmits a rotational driving force to the cam drive shaft 170 abuts against the inner housing 6a so that movement of the gear unit 140 in the axial direction of the rotor 4 is restricted. Thus, the input-side involute spline shaft portion 173 of the cam drive shaft 170 and the involute spline shaft receiving portion of the output-side spur gear 160 are engaged with each other so as to transmit a rotational driving force while permitting movement relative to each other in the axial direction of the rotor 4. Therefore, even if the cam drive shaft 170 is moved toward the outer side relative to the gear unit 140 in response to the adjustment, the input-side involute spline shaft portion 173 and the involute spline shaft receiving portion of the output-side spur gear 160 are kept engaged with each other. Hence, the rotational driving force of the electric motor 110 can be transmitted to the cam drive shaft 170 via the gear unit 140 while permitting adjustment. Note that the input-side involute spline shaft portion 173 is formed to extend in the axial direction in correspondence with the adjustment.
In the embodiment described above, the description has been given of the example of the configuration in which the pressing force of the inner pad 43 is detected using the pressing force sensor 31 and fed back to control the rotational driving of the electric motor 110. However, the application of the present invention is not limited to the example of the configuration. For example, the configuration may also be such that, instead of detecting the pressing force of the inner pad 43, a brake torque generated by pressing the inner pad 43 against the braking surface 4a is detected or the deceleration of the vehicle is detected to control the rotational driving of the electric motor 110.
In the embodiment described above, the description has been given of the example of the configuration in which the adjusting drive gear 38 is automatically driven to rotate in accordance with the gap between the inner pad 43 and the braking surface 4a to perform a gap adjustment. However, the present invention is not limited to the example of the configuration. Instead of the configuration, the configuration may also be such that an adjusting electric motor which drives the adjusting drive gear 38 to rotate is provided separately and the rotational diving of the adjusting electric motor is controlled to perform the gap adjustment.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2012/004375 | 7/5/2012 | WO | 00 | 12/23/2014 |