Braking system for a vehicle

Abstract

A braking system for a vehicle, comprising: a brake piston (1) that can be connected to a brake pad and is configured to perform a braking movement to press the brake pad against a friction surface; a hydraulic brake unit configured for hydraulic actuation of the braking movement of the brake piston (1); an electromechanical parking brake actuator configured for actuation of the braking movement of the brake piston (1), wherein the electromechanical parking brake actuator comprises: a spindle (5) rotatable by an electric motor, and a nut (6) mounted on the spindle (5) such that a rotational movement of the spindle (5) results in a translational movement of the nut (6), wherein the nut (6) is coupled to the brake piston (1) such that a translational movement of the nut (6) in the direction of the brake piston (1) triggers the braking movement of the brake piston (1); the braking system further comprising an elastic element (9).which couples the brake piston (1) to the nut (6), wherein the elastic element (9) is configured to drive a movement of the brake piston (1) in a direction opposite to the direction of the braking movement of the brake piston (1), wherein the elastic element (9) is held in a groove (10) with a bottom surface (18), characterized in that the bottom surface (18) tapers in the direction away from the brake pad and / or towards the electric motor.

Description

The registration relates to a braking system for a vehicle. Braking systems for vehicles are well-known. Generally, a vehicle can be equipped with a hydraulic brake system that uses brake fluid to transmit pressure from a master cylinder to the wheel brakes. The master cylinder may be connected to a brake pedal via a pushrod. The wheel brakes may have calipers connected to the master cylinder via hydraulic lines. The wheel brakes may have caliper pistons and brake pads connected to the caliper pistons. When the brake pedal is pressed, the brake pads can be pushed against a brake disc to slow down or stop the vehicle. Furthermore, vehicles can be equipped with an electronic parking brake to keep the vehicle securely stationary when parked. Typically, the driver activates the electronic parking brake with a button, and the brake pads are electrically applied to the wheels. In some vehicles, the electronic parking brake uses a computer-controlled motor, which may be mounted, for example, on each of the two rear brake calipers in a motor-on-caliper system. Related prior art is described in German Patent Applications DE 10 2010 033 255 A1 and US 2018 / 0298969 A1. In view of the aspects mentioned above, an objective of the present invention is to provide an improved braking system for a vehicle. In particular, the application aims to provide a compact and robust braking system that ensures reliable actuation and release of both a hydraulic and a parking brake system. This objective is achieved by a braking system for a vehicle with the features of claim 1. Optional further features and developments will become clear with reference to the dependent claims and the specific description in conjunction with the accompanying figures. The proposed braking system for a vehicle comprises a brake piston that can be connected to a brake pad. The brake piston is configured to perform a braking movement to press the brake pad against a friction surface. This braking movement is typically linear. The braking movement of the brake piston is generally directed toward the friction surface. The friction surface typically rotates when the vehicle is in motion. The friction surface may be coupled to a wheel of the vehicle. The friction surface is typically the surface of a brake disc. The brake disc may, in some embodiments, be considered part of the claimed braking system. The braking system may include a hydraulic brake and a parking brake. The proposed braking system also includes a hydraulic brake unit, which may form part of the hydraulic brake system. The hydraulic brake unit is designed to hydraulically actuate the brake piston's movement. The hydraulic brake unit may be part of, or form a component of, the hydraulic brake system, which can be a service brake or a driving brake. The hydraulic brake unit may be configured to decelerate and / or stop the vehicle. The hydraulic brake system typically uses a brake fluid containing, for example, glycol ethers or diethylene glycol, to hydraulically actuate the brake piston's movement. The hydraulic brake unit may include a master cylinder. The master cylinder may be coupled to the brake pedal, for example, via a pushrod.The master cylinder can be hydraulically connected to the brake piston for actuating its movement. A hydraulic chamber, which can be pressurized to effect the braking movement of the brake piston, can be located behind and / or enclosed within the brake piston. The braking system also includes an electromechanical parking brake actuator, which may be part of a parking brake. The electromechanical parking brake actuator is designed to actuate the braking movement of the brake piston. The electromechanical parking brake actuator can be configured to hold the vehicle stationary when parked. The proposed braking system may include a combined parking brake and hydraulic brake. Typically, both the parking brake and the hydraulic brake use the same brake piston for braking movement. The electromechanical parking brake actuator includes a spindle. The spindle is rotatable by an electric motor. Typically, the spindle rotates about a longitudinal axis. The longitudinal axis of the spindle usually points toward the brake pad and / or the brake disc. The spindle may be fixed in a translational position. The braking system may include a housing, such as a brake caliper housing.The spindle can be fixed translationally in relation to the housing. The electromechanical parking brake actuator also includes a nut that sits on the spindle. The nut is mounted on the spindle such that a rotational movement of the spindle results in a translational movement of the nut. This translational movement of the nut can be along the longitudinal axis of the spindle. In typical embodiments, the translational movement of the nut can be in the direction of the friction surface and / or away from the electric motor. In some embodiments, the nut has teeth on an inner surface. The spindle can have corresponding teeth on an outer surface. The teeth of the spindle can engage with the teeth of the nut. In other embodiments, however, the spindle can be a ball screw, so that the spindle is coupled to the nut via a set of balls. In most embodiments, the nut is rotationally fixed relative to the brake piston and / or the housing. The nut is coupled to the brake piston in such a way that a translational movement of the nut towards the brake piston triggers the braking movement of the brake piston. The nut typically has a surface facing the brake pad, e.g., an end face. To trigger the braking movement of the brake piston, the surface of the nut can press against the piston in most designs. The braking system also includes an elastic element. The elastic element connects the brake piston to the nut. The elastic element is configured to drive movement of the brake piston in a direction opposite to the direction of the braking movement of the brake piston, e.g., in a direction away from the brake pad. According to some embodiments, the elastic element is configured to push or pull the brake piston in a direction opposite to the direction of the braking movement of the brake piston. The brake piston may be movable relative to the nut to allow braking movement during hydraulic actuation. When the brake piston performs the braking movement during hydraulic actuation, the nut may be fixed. The elastic element may allow the brake piston to move forward relative to the nut when the hydraulic brake unit initiates the braking movement of the brake piston. The elastic element assists in retracting the brake piston when the parking brake is not fully applied. This makes the proposed brake system compact, robust, and reliable, reducing residual torque when applying the brake, i.e., when releasing the hydraulic brake and / or the parking brake. This can be particularly advantageous if a brake piston seal and / or brake pad springs, if present, are unable to reliably retract the piston on their own. For example, the elastic element can actively retract the brake piston. In typical designs, the elastic element is configured to drive the movement of the brake piston in such a way that, when the nut is moved, the brake piston is retracted in the opposite direction to its braking movement. This ensures that the brake piston retracts when the parking brake is released. Typically, the elastic element is configured to drive the movement of the brake piston such that, when the hydraulic actuation is released, the brake piston retracts. The elastic element can be configured to push or pull the brake piston so that it retracts after the hydraulic actuation is released, for example, after pressure in the hydraulic chamber has been relieved. In some embodiments, the movement of the brake piston is driven by an elastic force stored in the elastic element. The elastic element can be in direct contact with both the brake piston and the nut. Typically, the elastic element is attached to the nut. In particular, the elastic element can be attached to the nut in such a way that its movement relative to the nut is limited in a longitudinal direction. The brake piston can be movable relative to the elastic element. In some embodiments, the elastic element is arranged on a surface of the nut facing away from the spindle axis, which may be a side face of the nut. The elastic element can also contact an inner surface of the brake piston. The inner surface of the brake piston may be a surface facing the spindle axis. In other embodiments, the elastic element is attached to the brake piston. In particular, the elastic element can be attached to the brake piston in such a way that its movement relative to the brake piston is limited in a longitudinal direction.The nut can be movable relative to the elastic element. In some embodiments, the elastic element is arranged on a surface of the brake piston facing the spindle axis, which may be located in the nut. The elastic element can also contact an outer surface of the nut. The outer surface of the nut may be a surface facing away from the spindle axis. In some embodiments, the elastic element contacts an inclined surface. The inclined surface can be an inclined inner surface of the brake piston and / or an inclined outer surface of the nut. The inclined surface is generally conical and / or non-cylindrical. The inclined surface can taper away from the brake pad and / or towards the electric motor. The inclined surface can be angled such that a force exerted by the elastic element on the inclined surface of the brake piston drives the brake piston in a direction opposite to the direction of the piston's braking movement. In this way, the inclined surface can enable or improve the retraction of the brake piston after the hydraulic brake and / or parking brake is released. In some embodiments, the brake system includes a groove. The groove can be formed in the brake piston, particularly on an inner surface of the brake piston, or in the nut, particularly on an outer surface of the nut. The elastic element can be received in the groove. The elastic element can be slidably received in the groove, particularly such that the elastic element can slide in the longitudinal direction. The groove can have a bottom surface. The bottom surface can be in contact with the elastic element. The bottom surface can be inclined. The bottom surface can be conical and / or non-cylindrical. The bottom surface can taper away from the brake pad and / or towards the electric motor. In some embodiments, the elastic element is held between the bottom surface and the inclined surface.The bottom surface of the groove can be shaped to allow the elastic element to be held deeper in the groove when the elastic element is located in a portion of the groove farther from the brake pad and / or closer to the electric motor. Conversely, the bottom surface of the groove can be shaped to allow the elastic element to be held less deeply in the groove when the elastic element is located in a portion of the groove closer to the brake pad and / or farther from the electric motor. The angled bottom surface of the groove ensures that the elastic element offers reduced or no resistance to the brake piston's retraction movement after the hydraulic brake actuation is released. In this case, the elastic element can be pressed into the portion of the groove farther from the brake pad and / or closer to the electric motor.Furthermore, the support provided for the brake piston's retraction can be improved by pulling back the nut through the inclined base of the groove. In this case, the elastic element on the base can be pushed into the part of the groove that is closer to the brake pad and / or further away from the electric motor. This effectively reduces the resistance that the elastic element offers to the brake piston's retraction movement. In some embodiments, the elastic element comprises a spring-loaded ball designed to be held by a recess. The recess may be formed on an inner surface of the brake piston. In other embodiments, the recess may be formed in the nut. The recess and the spring-loaded ball may form a ball detent. The ball detent may be designed to cause movement of the brake piston opposite to the direction of the brake piston's movement, in order to retract the brake piston after the hydraulic brake and / or parking brake is released. Retraction of the brake piston may be achieved by the spring-loaded ball being drawn toward the recess or a portion thereof. The spring-loaded ball may be a metal ball. The spring-loaded ball may be received in a cylindrical recess, e.g., in a bored cylinder.The cylindrical recess can be located within the nut. The cylindrical recess can also be designed as a through-hole in the nut. This improves the evacuation of air bubbles and / or pressure equalization of the brake fluid. A spring can be accommodated within the cylindrical recess in such a way that it pushes the spring-loaded ball outwards. In some embodiments, the cylindrical recess is located within the brake piston. The elastic element can comprise several spring-loaded balls with the properties described above. In typical embodiments, the elastic element is configured to decouple the nut from the brake piston when the nut is retracted beyond a decoupling point. The decoupling point can be formed by an edge. This edge can be an inner surface of the brake piston or an outer surface of the nut. The brake system can be configured to decouple the nut from the brake piston when the nut is retracted more than at least 1 mm and / or more than at most 10 mm, for example, measured relative to a position where the nut is coupled to the brake piston such that the translational movement of the nut towards the brake piston would trigger the braking movement of the brake piston. The decoupling point allows for convenient replacement of the brake pad and / or calibration of the nut.The braking system is typically configured so that the nut and the brake piston are re-coupled upon subsequent actuation of the electromechanical parking brake actuator. In typical embodiments, the nut includes an end section in an area closest to the brake pad. The elastic element may be located in the end section of the nut. The nut may also include an anti-rotation element. This anti-rotation element can fix the nut against rotation relative to the brake piston. The anti-rotation element can, for example, be formed by a ridge on the nut. The anti-rotation element can engage with a portion of the brake piston to prevent the nut from rotating. Typically, the end section and / or the elastic element is located closer to the brake pad and / or further away from the electric motor than the anti-rotation element of the nut. The elastic element typically consists entirely or at least partially of an elastic material. The elastic element may be made of or contain an elastomer. In other embodiments, the elastic element is made of or contains a metal. In most embodiments, the elastic element is ring-shaped. The elastic element may be a spring ring. The elastic element may be, for example, an elastomer ring, such as a rubber ring. In other embodiments, the elastic element is a metallic spring ring. To enable particularly reliable operation, the elastic element may be a multiple spring ring, such as a metallic multiple spring ring. The multiple spring ring may comprise several leaf spring elements, for example, at least four leaf spring elements arranged around the circumference of the multiple spring ring.The elastic element can be a ring with a circular cross-section or a ring with a square cross-section. In typical embodiments, the elastic element allows the passage of fluid, particularly in the longitudinal direction. This enables the evacuation of air bubbles and / or pressure equalization of the brake fluid. Therefore, in some embodiments, the elastic element does not form a completely closed ring seal between the nut and the brake piston. The elastic element may consist of a slotted ring. The diameter of the elastic element is typically at least 10 mm and / or at most 50 mm. The width of the elastic element, measured longitudinally, can be at least 1 mm and / or at most 10 mm. The height or thickness of the elastic element, measured radially, can be at least 0.5 mm and / or at most 2 mm. Furthermore, a sealing element can be provided for the brake piston. This sealing element can be a sealing ring. It can be positioned between an outer surface of the brake piston and an inner surface of the housing. The sealing element can be designed to hydraulically seal the hydraulic chamber containing the brake fluid from the outside of the brake system. The sealing element can prevent rotation of the brake piston. In some embodiments, the sealing element is deformable and contributes to the retraction of the brake piston. In some embodiments, the elastic element can assist the retraction of the sealing ring, particularly when releasing the hydraulic brake. The braking system may include a brake caliper. The brake piston may be part of the brake caliper and may be a caliper piston. The brake caliper may include another brake piston whose technical characteristics correspond to those of the brake piston. The other brake piston may be connected to a different brake pad. The other brake piston may be configured to perform a braking movement to press the other brake pad against a different friction surface. The other friction surface may be a surface of the brake disc. The other friction surface may be located on a side of the brake disc opposite the friction surface. The electromechanical parking brake actuator may be coupled to an electronic control unit configured to actuate the electromechanical parking brake actuator.The electromechanical parking brake actuator may include the electric motor configured to rotate the actuator's spindle, or it may be coupled to the electric motor. The electronic control unit may be configured to automatically advance the nut by a lesser amount than the amount required to apply the parking brake after the parking brake is released. In some embodiments, the electric motor or the electronic control unit is coupled to a button. In some embodiments, the vehicle driver can activate the electromechanical parking brake using the button. The electric motor configured to rotate the actuator's spindle may, in some embodiments, be mounted on the brake caliper. Exemplary embodiments are described in conjunction with the following figures. Figs. 1(a) to (c) show a braking system according to a first embodiment, Figs. 2(a) to (c) show a braking system according to a second embodiment, Figs. 3(a) to (c) show a braking system according to a third embodiment, Figs. 4(a) to (c) show a braking system according to a fourth embodiment, Figs. 5(a) to (d) show a braking system according to a fifth embodiment, Figs. 6(a) to (c) show a braking system according to a sixth embodiment, and Figs. 7(a) to (d) show a detailed view of the braking system. Fig. 1(a) shows a cross-sectional view of a brake system for a vehicle according to a first embodiment. The brake system comprises a brake piston 1. The brake piston is arranged in a cylinder 2 of a brake caliper housing. A sealing ring 3 is arranged between the brake piston 1 and the cylinder 2, ensuring a seal between a hydraulic chamber 4 located inside and behind the brake piston and an external surface. The hydraulic chamber 4 is connected to a master cylinder (not shown) via hydraulic lines, so that the hydraulic fluid in the hydraulic chamber 4 can be pressurized to hydraulically actuate a braking movement (to the left) of the brake piston 1.When the brake piston 1 performs the braking movement, a brake pad (not shown), connected to a front portion of the brake piston 1, is pressed against a brake disc (not shown) of a wheel to decelerate or stop a moving vehicle. To ensure that a parked vehicle remains stationary, the drive movement of the brake piston 1 can be initiated by an electromechanical parking brake actuator of an electronic parking brake system. The electromechanical parking brake actuator comprises an electric motor (not shown) attached to the brake caliper housing (right) and a spindle 5. The spindle 5, which has teeth on its outer surface, can be rotated by actuation of the electric motor. The spindle 5 accommodates a nut 6, which has teeth on an inner surface. The nut 6 incorporates an anti-rotation element 7, formed by ribs on an outer surface of the nut 6. The anti-rotation element 7 of the nut 6 engages with the brake piston 1 to prevent rotation of the nut 6. When the spindle 5 is rotated by the electric motor, the nut 6 performs a translational movement (left or right). When the electronic parking brake is applied, the spindle 5 rotates so that the nut 6 moves to the left. In this case, an end face 8 of the nut 6 presses against the brake piston 1 to initiate the braking movement of the brake piston 1 and thus activate the parking brake. An elastic element 9 is positioned between the nut 6 and the brake piston 1 to couple the movement of the nut 6 and the brake piston 1 in certain situations.The elastic element 9 is formed by a shaped ring with an egg-shaped cross-section, but can also be an O-ring. In the embodiment shown, the elastic element 9 can consist of an elastomer, e.g., rubber, but in other embodiments it can have different properties, as explained below. Fig. 1(b) shows a detailed view of the coupling between the nut 6 and the brake piston 1. Corresponding and recurring features in the various figures are indicated by the same reference numerals. The coupling includes an angled snap-out mechanism with play. The elastic element 9 is held in a groove 10 of the nut 6 and contacts an inner surface 11 of the brake piston 1. The inner surface 11 of the brake piston 1 is tapered such that it has a larger inner diameter on the side facing the brake pad (left). The elastic element 9 and the inner surface 11 of the brake piston 1 couple the nut 6 and the brake piston 1 such that the brake piston 1 is retracted when the nut 6 is moved to the right during the release of the electronic parking brake, i.e., when the electric motor is actuated so that the spindle 5 rotates in a direction that retracts the nut 6.Furthermore, the coupling between the nut 6 and the brake piston 1 is designed such that the brake piston can move to the left to perform the braking action when the hydraulic brake is actuated. In this case, the nut 6 and the spindle 5 can be stationary. When the hydraulic actuation of the hydraulic brake is released, the elastic element 9 and the inclined inner surface 11 couple the nut 6 and the brake piston 1 such that the brake piston 1 is retracted (pushed / pulled to the right) by the elastic element 9. The brake piston 1 also has an edge 12 formed adjacent to the inner surface 11. The edge 12 forms a decoupling point.When the electric motor rotates the spindle 5 so that the nut 6 is retracted further to the right than is normally required to release the electronic parking brake, the connection between the nut 6 and the brake piston 1 can be disengaged for brake pad replacement, as the elastic element 9 slides to the right over the edge 12 of the brake piston 1. Upon subsequent application of the parking brake, during which the nut moves to the right, the nut 6 can re-engage with the piston 1, allowing the elastic element 6 to once again contact the inclined inner surface 11 of the brake piston 1. A perspective view of the nut 6 and the elastic element 9 is shown in Fig. 1(c). The braking system utilizes the retraction of nut 6 when releasing the parking brake or hydraulic brake to pull the brake piston away from the brake disc. Nut 6 is coupled to brake piston 1 via an elastic element 9, which allows release when the brake piston 1 needs to be moved forward by hydraulic pressure during hydraulic brake application. The elastic element 9 also allows for a small amount of play in the brake piston 1 when only minor movements are required. Furthermore, the elastic element 9 assists in the retraction of the sealing ring 3 and allows for additional retraction. The elastic element 9 also enables active retraction until a release force is reached. Finally, the elastic element allows for re-engagement when the electronic parking brake is applied. Figures 2(a) to (c) show a further embodiment of the elastic element 9 of the brake system. In this embodiment, the elastic element 9 is formed by a rubber ring with a square cross-section. Figures 3(a) to (c) show a further embodiment of the elastic element 9 of the brake system. In this embodiment, the elastic element 9 is formed by a metallic multi-spring ring with several leaf spring elements 17 arranged equidistantly around the circumference of the elastic element. Figures 4(a) to (c) show a further embodiment of the elastic element 9 of the brake system. In this embodiment, the elastic element 9 comprises several spring-loaded balls 13, which are received in a recess 14, e.g., a groove, on the inner surface of the brake piston 1. The spring-loaded balls 13 are held in a bore 15, which is designed as a through-hole in the nut 6.The spring-loaded balls 13 are each supported by a spring 16, which is received in a wider section of the bore 15. Figures 5(a) to (d) show another embodiment of the elastic element 9 of the brake system. In this embodiment, the elastic element 9 is formed by a metallic spring ring with a round cross-section. As shown in Figure 5(d), the elastic element 9 can be designed as a slotted ring with an opening in one ring section. In this way, suitable elasticity of the elastic element 9 can be achieved. Furthermore, the opening in the elastic element 9 allows fluid to flow in the longitudinal direction, enabling reliable escape of air bubbles and pressure equalization of the brake fluid. Figures 6(a) to (c) show another embodiment of the brake system. In this embodiment, the elastic element 9 is attached to an inner surface of the brake piston 1. The elastic element 9 is arranged in a groove in the inner surface of the brake piston 1 and contacts an outer surface of the nut 6. The operation is as described above or below for the case where the elastic element 9 is attached to the nut 6. Figure 6(c) shows a perspective view of part of the brake piston 1, from which the position of the elastic element 9 in the groove in the inner surface of the brake piston 1 can be seen. Figures 7(a) to (d) show the braking system in more detail. As shown, the elastic element 9 is held in the groove 10 formed in the nut 6. The groove 10 has an inclined bottom surface 18 which is in contact with the elastic element 9. The inclination of the bottom surface 18 is such that it tapers to the right. The elastic element 9 is held between the inclined bottom surface 18 of the groove 10 and the inclined inner surface 11 of the brake piston 1. In the situation shown in Figure 7(a), the parking brake and the hydraulic brake are applied, and the elastic element 9 is positioned in a right (deeper) part of the groove 10. As shown in Figure 7(b), when the parking brake is released, the nut 6 moves to the right away from the brake piston 1.As a result, the elastic element 9 moves towards a left (shallower) section of the groove 10, and there is essentially no effect on the brake piston 1 until the elastic element 9 reaches a left end of the groove 10. As shown in Fig. 7(c), the elastic element 9 is wedged between the inclined surface 11 of the brake piston 1 and the bottom surface 18 of the groove 10 when the hydraulic pressure is released shortly after the parking brake is disengaged. This causes the nut 6 to pull the brake piston 1 to the right to assist in its retraction. Additionally, the brake piston 1 moves further to the right due to the retraction force generated by the sealing ring 3. With purely hydraulic actuation, the elastic element is located at a right end of the groove 10, as shown in Fig. 7(d), with the elastic element 9 not interfering with the retraction force generated by the sealing ring 3. Features of the various embodiments, which are only disclosed in the exemplary embodiments, can be combined with each other and can also be claimed individually. Reference symbol list 1 Brake piston 2 Cylinder 3 Sealing ring 4 Hydraulic chamber 5 Spindle 6 Nut 7 Anti-rotation element 8 Nut face 9 Elastic element 10 Nut groove 11 Inner surface of brake piston 12 Edge 13 Leaf spring elements 13 Spring-loaded balls 14 Recess 15 Bore 16 Spring 17 Spring elements 18 Groove bottom

Claims

A braking system for a vehicle, comprising: a brake piston (1) that can be connected to a brake pad and is configured to perform a braking movement to press the brake pad against a friction surface; a hydraulic brake unit configured for hydraulic actuation of the braking movement of the brake piston (1); an electromechanical parking brake actuator configured for actuation of the braking movement of the brake piston (1), wherein the electromechanical parking brake actuator comprises: a spindle (5) rotatable by an electric motor, and a nut (6) mounted on the spindle (5) such that a rotational movement of the spindle (5) results in a translational movement of the nut (6), wherein the nut (6) is coupled to the brake piston (1) such that a translational movement of the nut (6) in the direction of the brake piston (1) triggers the braking movement of the brake piston (1); the braking system further comprising an elastic element (9).which couples the brake piston (1) to the nut (6), wherein the elastic element (9) is configured to drive a movement of the brake piston (1) in a direction opposite to the direction of the braking movement of the brake piston (1), wherein the elastic element (9) is held in a groove (10) with a bottom surface (18), characterized in that the bottom surface (18) tapers in the direction away from the brake pad and / or towards the electric motor. Brake system according to claim 1, characterized in that the elastic element (9) is configured to drive the movement of the brake piston (1) such that the brake piston (1) is retracted when the nut (6) is moved in a direction opposite to the braking movement of the brake piston (1). Brake system according to one of claims 1 or 2, characterized in that the elastic element (9) is configured to drive the movement of the brake piston (1) such that the brake piston is retracted when the hydraulic actuation of the brake movement of the brake piston (1) is released. Brake system according to one of claims 1 to 3, characterized in that the elastic element (9) is attached to the nut (6) or to the brake piston (1). Brake system according to one of claims 1 to 4, characterized in that the elastic element (9) contacts an inclined inner surface (11) of the brake piston (1) and / or an inclined outer surface of the nut (6). Braking system according to one of claims 1 to 5, characterized in that the elastic element (9) has a spring-loaded ball (13) configured to be received in a recess (14). Brake system according to one of claims 1 to 6, characterized in that the elastic element (9) is configured to decouple the nut (6) from the brake piston (1) when the nut (6) is retracted beyond a decoupling point. Braking system according to claim 7, characterized in that the decoupling point is formed by an edge (12). Brake system according to one of claims 1 to 8, characterized in that the nut (6) has an end section in an area that is closest to the brake pad, wherein the elastic element (9) is arranged in the end section of the nut (6). Braking system according to one of claims 1 to 9, characterized in that the elastic element (9) is ring-shaped. Braking system according to one of claims 1 to 10, characterized in that the elastic element (9) is made of or contains an elastomer. Braking system according to one of claims 1 to 10, characterized in that the elastic element (9) consists of or contains a metal. Braking system according to one of the preceding claims, characterized in that the elastic element (9) is a metallic multi-spring ring.

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