Braking system including motor-driven disc brake equipped with self-servo mechanism

An electrically operated braking system comprising a motor-driven disc brake including an electric motor as a drive source for braking a wheel of an automotive vehicle, and a motor control device for controlling said electric motor, said motor-driven disc brake further including:

• a disc rotor having a friction surface and rotating with said wheel;
• a friction pad movable for contact with said friction surface to restrict rotation of said disc rotor;
• a pad support mechanism for supporting said friction pad such that said friction pad is movable in a direction intersecting said friction surface;
• a pad pressing mechanism comprising said electric motor and a pressing member, said electric motor producing a drive force for moving said pressing member to force said friction pad against said friction surface of said disc rotor;
• a self-servo mechanism for providing a self-servo effect of boosting a friction force generated between said friction surface and said friction pad, on the basis of the friction force;
• and
• a mechanism including an elastic member for mechanically controlling a rate of change of said self-servo effect of said self-servo mechanism with a change in said drive force of said electric motor.

An electrically operated braking system comprising a motor-driven disc brake including an electric motor as a drive source for braking a wheel of an automotive vehicle, and a motor control device for controlling said electric motor, said motor-driven disc brake further including:

• a disc rotor having a friction surface and rotating with said wheel;
• a friction pad movable for contact with said friction surface to restrict rotation of said disc rotor;
• a pad support mechanism for supporting said friction pad such that said friction pad is movable in a direction intersecting said friction surface;
• a pad pressing mechanism comprising said electric motor and a pressing member, said electric motor producing a drive force for moving said pressing member to force said friction pad against said friction surface of said disc rotor;
• a self-servo mechanism for providing a self-servo effect of boosting a friction force generated between said friction surface and said friction pad, on the basis of the friction force;
• and
• a self-servo effect inhibiting mechanism for inhibiting said self-servo mechanism from providing said self-servo effect while a braking force between said wheel and a road surface is smaller than a predetermined first value,
• and wherein said self-servo-mechanism provides said self-servo effect by utilizing a movement of said friction pad with said disc rotor due to said friction force therebetween, such that said self-servo effect changes with an amount of said movement of said friction pad, said self-servo effect inhibiting mechanism including an elastic member whose elastic force inhibits the movement of said friction pad with said disc rotor, and wherein said pad support mechanism includes a stationary member having a pair of portions for supporting said friction pad at opposite end portions thereof which are opposite to each other in a rotating direction of said disc rotor, and said elastic member having opposite end portions one of which is associated with one of said opposite end portions Qf said friction pad toward which said friction pad is moved with said disc rotor during forward running of said automotive vehicle, the other of said opposite end portions of said elastic member being associated with one of said pair of portions of said stationary member which is remote from said one end portion of said friction pad.

An electrically operated braking system comprising a motor-driven disc brake including an electric motor as a drive source for braking a wheel of an automotive vehicle, and a motor control device for controlling said electric motor, said motor-driven disc brake further including:

• a disc rotor having a friction surface and rotating with said wheel;
• a friction pad movable for contact with said friction surface to restrict rotation of said disc rotor;
• a pad support mechanism for supporting said friction pad such that said friction pad is movable in a direction intersecting said friction surface;
• a pad pressing mechanism comprising said electric motor and a pressing member, said electric motor producing a drive force for moving said pressing member to force said friction pad against said friction surface of said disc rotor;
• a self-servo mechanism for providing a self-servo effect of boosting a friction force generated between said friction surface and said friction pad, on the basis of the friction force;
• and
• an excessive self-servo effect inhibiting mechanism for inhibiting said self-servo effect inhibiting mechanism for inhibiting an increase of said self-servo effect of said self-servo mechanism after a braking force between said wheel and a road surface exceeds a predetermined second value.

An electrically operated braking system comprising a motor-driven disc brake including an electric motor as a drive source for braking a wheel of an automotive vehicle, and a motor control device for controlling said electric motor, said motor-driven disc brake further including:

• a disc rotor having a friction surface and rotating with said wheel a friction pad movable for contact with said friction surface to restrict rotation of said disc rotor;
• a pad support mechanism for supporting said friction pad such that said friction pad is movable in a direction intersecting said friction surface;
• a pad pressing mechanism comprising said electric motor and a pressing member, said electric motor producing a drive force for moving said pressing member to force said friction pad against said friction surface of said disc rotor;
• and
• a self-servo mechanism for providing a self-servo effect of boosting a friction force generated between said friction surface and said friction pad, on the basis of the friction force,
• and wherein said electric motor has a non-energized off state, a first energized state for forward rotation thereof, and a second energized state for reverse rotation thereof, said pressing member being moved to press said friction pad toward said friction surface of said disc rotor when said electric motor is placed in said first energized state, and wherein said motor control device controls said electric motor such that an actual value of a pressing force by which said friction pad is forced against said friction surface is equal to a desired value, said electrically operated braking system further comprising:
• insufficient increase preventing means for preventing a shortage of increase of said actual value of said pressing force by locking said pressing member against a reaction force transferred from said friction pad to said pressing member, so as to prevent a shortage of increase of said actual value of said pressing force, when said actual value is required to be increased during operation of said self-servo mechanism.

An electrically operated braking system comprising a motor-driven disc brake including an electric motor as a drive source for braking a wheel of an automotive vehicle, and a motor control device for controlling said electric motor, said motor-driven disc brake further including:

• a disc rotor having a friction surface and rotating with said wheel;
• a friction pad movable for contact with said friction surface to restrict rotation of said disc rotor;
• a pad support mechanism for supporting said friction pad such that said friction pad is movable in a direction intersecting said friction surface;
• a pad pressing mechanism comprising said electric motor and a pressing member, said electric motor producing a drive force for moving said pressing member to force said friction pad against said friction surface of said disc rotor;
• and
• a self-servo mechanism for providing a self-servo effect of boosting a friction force generated between said friction surface and said friction pad, on the basis of the friction force,
• and wherein said electric motor includes a stator, a rotor and a motor housing in which said stator and said rotor are accommodated, and said pad pressing mechanism includes:
• a rotatable member rotatable about an axis thereof by said electric motor;
• a linearly movable member disposed rearwardly of said pressing member such that said movable member is linearly movable in said direction intersecting said friction surface of said disc rotor;
• a motion converting mechanism for converting a rotary motion of said rotatable member into a linear motion of said linearly movable member, to move said pressing member for forcing said friction pad against said friction surface;
• a caliper including a portion functioning as said motor housing, and supporting said linearly movable member such that said linearly movable member is linearly movable;
• and
• a rotary support mechanism for supporting said rotatable member rotatably relative to said caliper, said rotary support mechanism enabling said caliper to receive as a thrust load a reaction force from said rotatable member while said friction pad is forced against said friction surface,
• and wherein said rotary support mechanism includes a support structure for reducing an influence of at least one of a first reaction force and a second reaction force upon said electric motor, said first reaction force being received as an offset load by said rotatable member from said linearly movable member during an operation of said motor-driven disc brake, and said second reaction force being received by said caliper from said rotatable member during the operation of said motor-driven disc brake,
• and further wherein said support structure includes a first structure for restricting an inclination of said axis of said rotatable member by said first reaction force during the operation of said motor-driven disc brake.