Brakes – Wheel – Axially movable brake element or housing therefor
Reexamination Certificate
2000-03-30
2001-08-28
Oberleitner, Robert J. (Department: 3613)
Brakes
Wheel
Axially movable brake element or housing therefor
C188S071900, C188S00111E, C188S162000, C188S1960BA, C188S1960BA, C192S084600, C192S084700
Reexamination Certificate
active
06279691
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electric braking device in which a brake force is generated when a brake element is pushed to a rotating member by operating an electric motor according to an electric signal, and in which the response property is excellent at the beginning of braking operation and the force transmitting efficiency is high after a brake pad and the rotating member are frictionally engaged with each other.
2. Description of the Related Art
An electric braking device is well known in which an electric motor is operated according to an electric signal so that a brake element (brake pad) is pushed to a rotating member (brake rotor) so that a brake force is generated. An example of the electric braking device is disclosed in JP-W-10-504876.
This electric braking device is composed as follows. Rotation of the electric motor is reduced by the reduction device and converted into a liner motion, so that the brake pad opposed to the brake rotor is moved to the brake rotor so as to conduct braking operation.
In the electric braking device described in the above patent publication, the force transmitting and converting mechanism for converting the torque of the electric motor into a pushing force for pushing the brake pad is composed of a roller screw, the force transmitting efficiency of which is high, which is used instead of a force transmitting and converting mechanism composed of a simple screw and nut. However, compared with the simple screw and nut mechanism, the roller screw mechanism is disadvantageous in that a large space is required for housing the electric motor and speed reduction mechanism, so that it becomes difficult to miniaturize the electric braking device. Further, the roller screw is relatively expensive. Therefore, it is difficult to decrease the cost of the electric braking device.
Another electric braking device is described in JP-W-8-510316.
The electric braking device described in the above patent publication includes a gear transmitting device, which is arranged between the electric motor and the brake pad, for pushing the brake pad to the rotating member (brake rotor). There are provided two clutch mechanisms in this gear transmitting device. When the first clutch mechanism is connected and the second clutch mechanism is disconnected, it is possible to obtain various approach speeds and fastening forces. After that, when the first clutch mechanism is disconnected and the second clutch mechanism is connected, it is possible to obtain a higher fastening force, that is, it is possible to obtain a higher brake force. This braking device is advantageous in that the brake pad can be quickly moved at the beginning of braking operation and further when the clutch is changed over after the braking operation, it is possible to obtain a higher fastening force. However, the above braking device is disadvantageous in that the structure becomes complicated and it is difficult to miniaturize the braking device because the force transmitting and converting mechanism is composed of the gear mechanism and two clutches.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above problems and provide an electric braking device including a force transmitting and converting mechanism in which a ramp mechanism is arranged between the electric motor and the brake pad. Due to the above structure, the efficiency of the force transmitting and converting mechanism having the ramp mechanism is higher than that of the screw and nut mechanism, and further it is possible to miniaturize the braking device and decrease the cost compared with the roller screw mechanism. Further, even when the brake pad wears, it can follow the wear smoothly. Furthermore, at the beginning of braking operation in which a longer stroke of the brake pad is required, it is possible to obtain a longer stroke, and it is possible to obtain a strong braking force in the process of braking operation.
The force transmitting and converting mechanism adopted by the electric braking device of the present invention includes: a gear rotated by the rotation of an electric motor; a nut arranged being opposed to this gear; and a rotating body arranged between the gear and the nut. The force transmitting and converting mechanism adopted by the electric braking device of the present invention further includes: a ramp mechanism operated so that the nut can be separated from the gear by the relative rotation of the gear and the nut; a screw member, which is not rotated, screwed to the nut member; and a brake pad arranged in the screw member. The ramp mechanism pushes the gear and nut integrally until the brake pad comes into contact with the brake rotor by a predetermined pushing force. When the brake pad comes into contact with the brake rotor by the predetermined pushing force, the ramp mechanism allows a relative rotation of the nut and gear, so that the nut member can be moved in the direction of the rotating member. In this way, the brake pad can be quickly moved at the beginning of braking operation, and it is possible to obtain a strong fastening force after the braking operation.
In order to accomplish the above object, the present invention adopts an electric braking device comprising a force transmitting and converting mechanism for pushing a rotating member with a brake element by a drive force generated by an electric motor, the force transmitting and converting mechanism including: a gear rotated by the electric motor; a nut arranged being opposed to the gear; a rotating body arranged between the gear and the nut; a ramp mechanism operated so that the gear and the nut can be separated from each other by a relative rotation of the gear with the nut; a screw member, which is not rotated, screwed to the nut; and a brake element operationally coming into contact with the screw member, wherein the ramp mechanism integrally rotates the gear and the nut until the brake element comes into contact with the rotating member by a predetermined pushing force, and the ramp mechanism allows the gear and the nut to rotate relatively with each other when the brake element comes into contact with the rotating member by a pushing force not less than the predetermined pushing force, so that the nut can be moved in a direction of the rotating member.
The ramp mechanism includes: inclined grooves formed on respective faces on which the gear and nut are opposed to each other; and a rotating body held between the inclined grooves, wherein the inclined grooves are formed in such a manner that the depth formed by the inclined grooves gradually becomes shallow when the nut and gear are rotated relatively with each other, and a recess portion for holding the rotating body is formed in the deepest portion of each inclined groove, and a wall portion for prohibiting the rotating body from moving is formed at an end portion of the most shallow portion of each groove.
REFERENCES:
patent: 5915504 (1999-06-01), Doricht
patent: 5949168 (1999-09-01), Dieckmann et al.
patent: 6173820 (2001-01-01), Blosch et al.
patent: 6176352 (2001-01-01), Maron et al.
patent: 6213256 (2001-04-01), Schaffer
patent: 8-510316 (1996-10-01), None
patent: 10-504876 (1998-05-01), None
Kawase Kazuo
Takahashi Kimio
Akebono Brake Industry Co. Ltd.
King Bradley
Morgan & Lewis & Bockius, LLP
Oberleitner Robert J.
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