FRICTION BRAKE SYSTEM FOR A VEHICLE
The present application relates to a friction brake system ( 1 ) for a vehicle. The friction brake system ( 1 ) comprises a braking member ( 12 ) connectable to at least one brake pad and configured for pressing the brake pad against a friction surface. The system ( 1 ) further comprises a transmission unit ( 2 ) configured for converting a rotary motion generated by an electric motor ( 30 ) into a braking motion of the braking member ( 12 ). The transmission unit ( 2 ) comprises a ball-in-ramp assembly ( 3 ) having a first plate ( 9 ) with at least one groove ( 23 ), a second plate ( 10 ) with at least one groove ( 22 ) facing the groove ( 23 ) of the first plate ( 9 ), and at least one ball ( 11 ) arranged between the first plate ( 9 ) and the second plate ( 10 ). The ball ( 11 ) is retained by the groove ( 23 ) of the first plate ( 9 ) and the groove ( 22 ) of the second plate ( 10 ). Further, the ball-in-ramp ( 3 ) assembly is configured to convert a rotary motion of the first plate ( 9 ) into a translational motion of the second plate ( 10 ) with respect to the first plate ( 9 ). The first plate ( 9 ) is configured to be rotated by the electric motor ( 30 ). Further, at least one of the first plate ( 9 ) and the second plate ( 10 ) is mechanically coupled with the braking member ( 12 ) such that a rotation of the first plate ( 9 ) causes the braking motion of the braking member ( 12 ). A depth of the groove ( 23, 24 ) of at least one of the first plate ( 9 ) and the second plate ( 10 ) increases between a first portion ( 24 ) and a second portion ( 25 ) of the groove ( 23, 24 ) in a non-linear manner such that a path defined by the groove ( 23, 24 ) is steeper in the first portion ( 24 ) than in the second portion ( 25 ).
1 . A friction brake system ( 1 ) for a vehicle, comprising
a braking member ( 12 ) connectable to at least one brake pad and configured for pressing the brake pad against a friction surface, and
a transmission unit ( 2 ) configured for converting a rotary motion generated by an electric motor ( 30 ) into a braking motion of the braking member ( 12 ),
characterized in that the transmission unit ( 2 ) comprises a ball-in-ramp assembly ( 3 ) having:
a first plate ( 9 ) with at least one groove ( 24 ),
a second plate ( 10 ) with at least one groove ( 23 ) facing the groove ( 24 ) of the first plate ( 9 ), and
at least one ball ( 11 ) arranged between the first plate ( 9 ) and the second plate ( 10 ), wherein the ball ( 11 ) is retained by the groove ( 23 ) of the first plate ( 9 ) and the groove ( 22 ) of the second plate ( 10 );
wherein the ball-in-ramp assembly ( 3 ) is configured to convert a rotary motion of the first plate ( 9 ) into a translational motion of the second plate ( 10 ) with respect to the first plate ( 9 ),
wherein the first plate ( 9 ) is configured to be rotated by the electric motor ( 30 ) and at least one of the first plate ( 9 ) and the second plate ( 10 ) is mechanically coupled with the braking member ( 12 ) such that a rotation of the first plate ( 9 ) causes the braking motion of the braking member ( 12 ),
wherein a depth of the groove ( 22 , 23 ) of at least one of the first plate ( 9 ) and the second plate ( 10 ) increases between a first portion ( 24 ) and a second portion ( 25 ) of the groove ( 22 , 23 ) in a non-linear manner such that a path ( 27 , 28 ) defined by the groove ( 24 ) is steeper in the first portion ( 24 ) than in the second portion ( 25 ).
2 . The friction brake system ( 1 ) of claim 1 , characterized in that the groove ( 23 ) of the first plate ( 9 ) and the groove ( 22 ) of the second plate ( 10 ) each define a path ( 27 , 28 ) having a radial component, wherein the ball ( 11 ) is held at an intersection point ( 29 ) of the path ( 27 ) defined by the groove ( 23 ) of the first plate ( 9 ) with the path ( 28 ) defined by the groove ( 22 ) of the second plate ( 10 ).
3 . The friction brake system ( 1 ) of claim 2 , characterized in that neighbouring grooves ( 23 , 23 ′) of the first plate ( 9 ) overlap at a circumferential position.
4 . The friction brake system ( 1 ) of claim 1 , characterized in that the grooves ( 23 ) of the first plate ( 9 ) and the grooves ( 22 ) of the second plate ( 10 ) have an identical shape at least in sections.
5 . The friction brake system ( 1 ) of claim 1 , characterized by a planetary gear ( 4 ), wherein the first plate ( 9 ) is configured to be rotated by the electric motor ( 30 ) via the planetary gear ( 4 ).
6 . The friction brake system ( 1 ) of claim 1 , characterized in that the ball-in-ramp assembly ( 3 ) comprises at least three grooves ( 23 , 23 ′) of the first plate ( 9 ), at least three grooves ( 22 , 22 ′) of the second plate ( 10 ), and at least three balls ( 11 , 11 ′) retained by pairs of the grooves of the first and second plates ( 9 , 10 ).
7 . The friction brake system ( 1 ) of claim 1 , characterized in that the ball-in-ramp assembly ( 3 ) comprises at least five grooves ( 23 , 23 ′) of the first plate ( 9 ), at least five grooves ( 22 , 22 ′) of the second plate ( 10 ), and at least five balls ( 11 , 11 ′) retained by pairs of the grooves of the first and second plates.
8 . The friction brake system ( 1 ) of claim 1 , characterized by a housing ( 18 ), wherein the second plate ( 10 ) is held such that it is not rotatable with respect to the housing ( 18 ).
9 . The friction brake system ( 1 ) of claim 1 , characterized in that the braking member ( 12 ) comprises a caliper housing ( 33 ) connectable to a first brake pad and a braking bolt ( 13 ) connectable to a second brake pad, wherein the caliper housing ( 33 ) and the braking bolt ( 13 ) are each coupled with one of the first plate ( 9 ) and the second plate ( 10 ) such that the caliper housing ( 33 ) and the braking bolt ( 13 ) are configured to press the first and second brake pads against opposing surfaces of a brake disc when the braking member ( 12 ) executes the braking motion.
10 . The friction brake system ( 1 ) of claim 1 , characterized by a housing ( 18 ), wherein the caliper housing ( 33 ) and the braking bolt ( 13 ) are held such that they execute a translational motion with respect to the housing ( 18 ) when the braking member ( 12 ) executes the braking motion.
11 . The friction brake system ( 1 ) of claim 9 , characterized in that the first plate ( 9 ) is coupled with the caliper housing ( 33 ) and the second plate ( 10 ) is coupled with the braking bolt ( 13 ) and/or characterized in that the first plate ( 9 ) is coupled with the braking bolt ( 13 ) and the second plate ( 10 ) is coupled with the caliper housing ( 33 ).
12 . The friction brake system ( 1 ) of claim 1 , characterized by an axial needle bearing ( 17 ), which supports the first plate ( 9 ).
13 . A parking brake for a vehicle comprising the friction brake system ( 1 ) of claim 1 , wherein the friction brake system ( 1 ) is configured to keep the vehicle motionless when parked by pushing the brake pad against the friction surface.
14 . A service brake for a vehicle, comprising the friction brake system ( 1 ) of claim 1 , wherein the friction brake system ( 1 ) is configured to reduce a rotational speed of a wheel by pushing the brake pad against the friction surface.