Disk brake

A disk brake comprising:

• a piston pressing one of a pair of pads against a rotor, the pads being disposed at opposite sides, respectively, of the rotor to face each other across the rotor in a direction of an axis of the rotor;
• a caliper body having a cylinder in which the piston is movably disposed;
• an electric motor provided on the caliper body;
• and
• a parking brake mechanism provided in the caliper body to propel and hold the piston in a braking position,
• the parking brake mechanism having:
• a ball-and-ramp mechanism moving the piston to the braking position in response to rotation of the electric motor;
• a rotating member rotatably provided in a rotor diametrical direction of a ball groove of the ball-and-ramp mechanism;
• and
• a screw mechanism holding the piston in the braking position after moving the piston to the braking position, together with the ball-and-ramp mechanism, in response to rotation of the electric motor;
• wherein the ball-and-ramp mechanism has a first ramp which can be rotated and rectilinearly moved, a second ramp, and a ball disposed between the first ramp and the second ramp,
• wherein the screw mechanism comprises a first thread provided on the first ramp and a second thread provided on the rotating member and engaged with the first thread,
• wherein the piston is held in the braking position by the first thread and the second thread of the screw mechanism,
• wherein the second ramp is an input member rotated by rotation of the electric motor transmitted thereto, and
• wherein the first ramp is a follower member rotating together with the input member so that a relative distance between the follower member and the input member in a direction of an axis of rotation increases when a rotation difference is generated between the follower member and the input member, and
• wherein the follower member transmits rotational force to the screw mechanism.

A disk brake comprising:

• a caliper body having a cylinder in which a piston is movably disposed to press a pad against a rotor, the caliper body further having an electric motor;
• and
• a parking brake mechanism provided in the caliper body to propel and hold the piston in a braking position;
• the parking brake mechanism having:
• a ball-and-ramp mechanism for moving the piston to the braking position in response to rotation of the electric motor;
• a rotating member rotatably provided in a rotor diametrical direction of a ball groove of the ball-and-ramp mechanism,
• a screw mechanism holding the piston in the braking position after moving the piston to the braking position, together with the ball-and-ramp mechanism, in response to rotation of the electric motor;
• and
• an abutting member abutting against the piston when a relative distance between the input member and the follower member increases;
• wherein the ball-and-ramp mechanism has a first ramp which can be rotated and rectilinearly moved and a second ramp disposed in an axial direction of the rotor of the first ramp and away from the pad relative to the first ramp;
• wherein the screw mechanism comprises a first thread provided on the first ramp and a second thread provided on the rotating member and engaged with the first thread;
• wherein the second ramp is an input member rotated by rotation of the electric motor transmitted thereto;
• wherein the first ramp is a follower member rotatable together with the input member so that a relative distance between the follower member and the input member in a direction of an axis of rotation increases when a rotation difference is generated between the follower member and the input member;
• wherein the follower member transmits rotational force to the screw mechanism;
• and
• wherein the screw mechanism has a screw member rotatable relative to the first thread so that the first thread and the second thread move relative to each other by a distance equal to an increase in the relative distance when a rotation difference is generated between the input member and the following member;
• wherein the screw member is configured to transmit thrust generated in the abutting member when the piston is held, to the caliper body through a thread engagement between the first thread and the second thread, and the first thread and the second thread hold the piston in the braking position.