Electromechanical vehicle brake and procedures

Abstract

An electromechanical vehicle brake (10) is described, comprising at least one brake caliper (12, 14) in which a space (20) for receiving a brake rotor (22) is provided, a first linearly guided brake piston (32), a first piston-adjacent brake pad (36) associated with the first brake piston (32) and movable by it, a second linearly guided brake piston (34), and a second piston-adjacent brake pad (38) associated with the second brake piston (34) and movable by it. The brake pads (36, 38) are associated with a common brake rotor (22) and can be applied to the brake rotor (22) by their associated brake pistons (32, 34).The vehicle brake (10) further comprises a third brake pad (40) located opposite the first brake pad (36), located further away from the piston, and a fourth brake pad (42) located further away from the second brake pad (38), located closer to the piston, and a drive assembly (44) for moving the two brake pistons (32, 34) between a retracted position and an extended position. Furthermore, a method for operating an electromechanical vehicle brake (10) is described.

Description

[0001] The invention relates to an electromechanical vehicle brake and a method for operating an electromechanical vehicle brake.

[0002] Electromechanical vehicle brakes, which are used in vehicles, particularly as service brakes, are typically designed with a desired clamping force of the vehicle brake in mind. The higher the clamping force requirement, the larger the vehicle brake components must be. In particular, the size of the brake piston increases with increasing clamping force requirement. This is disadvantageous with regard to installation space requirements. In particular, with increasing size of the brake piston, the installation space required in the radial direction increases. Furthermore, with existing vehicle brakes, additional support for a back plate of the brake pad is necessary for clamping force requirements of 100 kN or more, which results in additional costs.

[0003] It is therefore an object of the invention to provide an optimized electromechanical vehicle brake for high clamping force requirements, which is optimized with regard to size and costs.

[0004] This object is achieved according to the invention by an electromechanical vehicle brake with at least one brake caliper in which an intermediate space for receiving a brake rotor is provided, a first linearly guided brake piston, a first brake pad near the piston, which is assigned to the first brake piston and is to be moved by it, a second linearly guided brake piston, and a second brake pad near the piston, which is assigned to the second brake piston and is to be moved by it, wherein the brake pads are assigned to a common brake rotor and can be applied to the brake rotor by their assigned brake piston. The vehicle brake further comprises a third brake pad remote from the piston, opposite the first brake pad near the piston, and a fourth brake pad remote from the piston, opposite the second brake pad near the piston, and a drive assembly for moving the two brake pistons between a retracted and an extended position.

[0005] By having two separate brake pistons and separate brake pads, higher clamping forces can be achieved than with a single piston, while at the same time, the size of the individual brake pistons is reduced compared to a vehicle brake with the same clamping force and only one brake piston. In particular, the reduced brake piston size reduces the installation space required in the radial direction. Furthermore, no additional support for the brake pads is necessary, which also reduces the installation space required in the actuation direction.

[0006] The vehicle brake according to the invention also has the advantage that the presence of two separate brake pistons achieves a better and more even distribution of force and pad pressure.

[0007] The reduced size of the individual brake pistons also ensures improved dynamic behavior due to the reduction in inertial forces, thus achieving a high degree of flexibility in driving dynamics control.

[0008] For example, superimposed force control is possible. Specifically, it's possible to implement an ABS function with one brake piston during a braking operation, while the second brake piston continuously brakes.

[0009] In addition, more precise force sensing of the clamping force is possible because a smaller force measuring range per brake piston has to be covered compared to a vehicle brake with a single, larger piston.

[0010] A further advantage is that the use of two brake pistons creates an additional level of redundancy, since if one brake piston fails, there is still one brake piston available for braking.

[0011] The first and second brake pistons are in particular guided parallel to each other.

[0012] Both brake pistons primarily define service brakes. This means that the brake pistons are applied during normal service braking and not only during parking braking or, exceptionally, as a parking brake in an emergency braking situation. Consequently, the two brake pistons play a significant role in controlling driving dynamics.

[0013] Preferably, the two brake pistons have the same dimensions and / or all brake pads are identical parts. This means that the brake pistons have the same length and / or diameter. In particular, the brake pistons are also identical parts. Using identical parts reduces the variety of components, which is advantageous with regard to the manufacturing costs of the vehicle brake.

[0014] The vehicle brake may comprise a brake carrier component that can be attached to a vehicle axle and on which the at least one brake caliper is guided. This allows the at least one brake caliper to be attached to the vehicle axle easily and reliably.

[0015] For example, the vehicle brake has a first brake caliper, to which the first brake piston is assigned, and a second brake caliper separate from the first brake caliper, to which the second brake piston is assigned, wherein the first brake caliper and the second brake caliper are fastened to the brake carrier component. The use of two separate brake calipers is advantageous over the use of a common, one-piece brake caliper, as the component complexity and thus the manufacturing costs are reduced for smaller, individually manufactured brake calipers. In particular, it is conceivable to adopt the individual brake calipers from a different series, thus eliminating the costs of manufacturing a tool.

[0016] In principle, however, it is also conceivable that both brake pistons are guided in a single-piece, common brake caliper.

[0017] The brake calipers can be identical parts, further reducing component diversity.

[0018] According to one embodiment, the brake carrier component has a central web between the two brake calipers, viewed in the direction of movement of the brake pistons, wherein two base sections extend from an end of the central web near the wheel hub and run away from each other at an obtuse angle from the central web, in particular at an angle of at least 120°. A further lateral web can extend from each of the ends of the base sections opposite the central web, wherein a receiving space for an associated brake caliper is formed between the central and the lateral webs. The brake carrier component thus has a double U-shape or W-shape. This enables a particularly compact design of the vehicle brake. In addition, such a brake carrier component has a high level of stability.

[0019] The central web preferably forms an angle of 120° with the base sections.

[0020] Additional ribbing may be present on the brake carrier component between the base sections for stabilization.

[0021] The base sections can be formed by two common, angled, spaced-apart legs, with arms projecting from the legs at the angle, which are part of the central web and are connected to each other at their free ends by a bridge. Arms projecting from the free ends of the legs can be part of the lateral webs, and the arms of each lateral web are connected at their free ends by a bridge, with the brake rotor being able to be accommodated between the legs and arms. This means that both the base sections and the central web and the lateral webs are formed by two parallel struts. In this way, the brake carrier component can be manufactured with a minimum of material, which also keeps the weight of the brake carrier component low, while the brake carrier component has a high level of stability.Apart from that, because the base sections are formed by two spaced legs, the space between them is accessible for accommodating the rotor.

[0022] The first brake caliper and the second brake caliper can be guided on one side to the central web of the brake carrier component, and on the opposite side to a corresponding one of the two lateral webs. This ensures stable mounting of both brake calipers. The fact that both brake calipers are guided equally on the central web contributes to a compact design.

[0023] For example, the first brake caliper and the second brake caliper are attached to the front of the brake carrier component, particularly by means of bolts. This allows for a floating mounting of the brake calipers.

[0024] The drive assembly preferably comprises a first electric motor and a second electric motor separate from the first electric motor, wherein the first electric motor is assigned to the first brake piston in order to move the first brake piston between the retracted position and the extended position, and the second electric motor is assigned to the second brake piston in order to move the second brake piston between the retracted position and the extended position. The use of two separate electric motors achieves better heat dissipation. In addition, additional redundancy is provided because if one electric motor fails, a braking operation can still be carried out using the second electric motor. For braking operations in which the maximum clamping force is not required, which is the case for the majority of braking operations, one brake piston is sufficient to apply the required clamping force.By having two electric motors, it is also possible to control the brake pistons alternately, which is advantageous in terms of energy consumption and wear of the vehicle brake.

[0025] Both electric motors preferably have the same power output. In particular, the motors are identical, which in turn reduces the variety of components. For example, the motors can be used as common parts from other series.

[0026] The electric motors are coupled to the brake pistons via a gear system in a conventional manner. For example, a planetary gear and a recirculating ball screw drive are provided to couple the electric motors to the associated brake piston.

[0027] However, it is also conceivable that there is only one electric motor, which includes a differential gear for moving both brake pistons simultaneously.

[0028] By adopting identical parts from other series, in particular the brake pistons, brake calipers and / or electric motors, the development risk and development time can be reduced.

[0029] According to one embodiment, the drive assembly has a first control unit and a second control unit separate from the first control unit, wherein the first control unit is configured to control the first electric motor and the second control unit is configured to control the second electric motor, wherein the control units each have their own electronic connection. This allows the control units to be connected to different on-board networks. This provides additional redundancy in the event of a failure of one on-board network. Furthermore, the use of two control units is also advantageous with regard to heat dissipation, since the power electronics are divided.

[0030] The control units can be housed in a single enclosure or in separate enclosures. Housing them in separate enclosures also contributes to better heat dissipation.

[0031] According to one embodiment, at least one of the two brake pistons is assigned a parking lock or parking brake function in addition to the service brake function. The parking brake function is implemented, in particular, via the control unit assigned to the brake piston. This eliminates the need for an additional parking brake.

[0032] The object is further achieved according to the invention by a method for operating an electromechanical vehicle brake according to the invention, wherein the two brake pistons are actuated simultaneously or alternately during a service braking operation. In this way, different braking scenarios can be realized. For decelerations in the lower force range, the actuation of a single brake piston is sufficient. By actuating only one piston, energy consumption is reduced. Alternating actuation ensures even pad wear. If high deceleration is required, both brake pistons can be actuated simultaneously to achieve high braking force.

[0033] In addition to the service brake function, both brake pistons can be assigned a parking lock function. In a first process step, when a vehicle is parked, both brake pistons are activated to form a parking lock. During the parking period, the two brake pistons are retensioned at different times. In this context, retensioning means that the brake piston is extended further if the braking force decreases as the vehicle brake cools. Retensioning requires a brief release of the parking lock. Due to the time-delayed retensioning, a parking lock is always active, so no additional safeguards are required during retensioning.

[0034] Further advantages and features of the invention will become apparent from the following description and the accompanying drawings, to which reference is made. In the drawings: - Fig. 1 a vehicle brake according to the invention in a perspective rear view, - Fig. 2 the vehicle brake Fig. 1 in perspective front view, - Fig. 3 a longitudinal section through the vehicle brake Fig. 1, - Fig. 4 a view of the vehicle brake from Fig. 1 from diagonally below, - Fig. 5 a cross-section through the vehicle brake Fig. 1, - Fig. 6 a parking lock of the vehicle brake according to the invention, - Fig. 7 a perspective rear view of an alternative embodiment of a vehicle brake according to the invention, - Fig. 8 is a perspective rear view of yet another embodiment of a vehicle brake according to the invention, and - Fig. 9 the vehicle brake Fig. 8 in a view from below.

[0035] The Fig. 1 and Fig. 2 each show a perspective view of a vehicle brake 10. The vehicle brake 10 is an electromechanically actuated brake.

[0036] The vehicle brake 10 comprises a first brake caliper 12 and a second brake caliper 14. The two brake calipers 12, 14 are identical parts, i.e., they are of identical design.

[0037] The brake calipers 12, 14 are guided on a brake carrier component 16 which can be fastened to a vehicle axle.

[0038] The brake calipers 12, 14 are further fastened to the brake carrier component 16 by means of bolts 18, in particular on the front side.

[0039] In each brake calliper 12, 14, a space 20 is provided to accommodate a brake rotor 22 (see Fig. 3).

[0040] In Fig. 1 also shows two separate housings 24 in which a first control unit 26 and a second control unit 28 are housed (see Fig. 3).

[0041] The control units 26, 28 are designed in particular as a printed circuit board.

[0042] The control units 26, 28 each have their own electronic connection 30.

[0043] The vehicle brake 10 according to Fig. 1 further comprises a first linearly guided brake piston 32 and a second linearly guided brake piston 34, as shown in the sectional view in Fig. 3 is illustrated.

[0044] The brake carrier component 16 is in Fig. 3 not shown for the sake of simplicity.

[0045] Each brake piston 32, 34 is assigned to one of the two brake calipers 12, 14.

[0046] The two brake pistons 32, 34 each define a service brake. This means that the brake pistons 32, 34 are used to decelerate the vehicle during normal driving.

[0047] The Fig. 3 illustrates equally the first brake piston 32 and the second brake piston 34. In particular, the Fig. 3 illustrate components with the exception of the brake rotor 22 in the vehicle brake 10 according to the invention, which are present in duplicate.

[0048] The two brake pistons 32, 34 have the same dimensions, i.e., the same length and the same diameter. Preferably, the two brake pistons 32, 34 are identically designed.

[0049] Each brake piston 32, 34 is assigned its own pair of brake pads, more precisely, on the one hand, a brake pad 36, 38 close to the piston to be moved by it, wherein both brake pads 36, 38 are assigned to the brake rotor 22, so that the brake rotor 22 represents a common rotor for the two brake pads 36, 38.

[0050] In addition, on the other hand, each brake pad 36, 38 close to the piston is opposite a brake pad 40, 42 far from the piston.

[0051] The brake pads 36, 38, 40, 42 each comprise a back plate 41 and a brake pad 43 arranged on the back plate 41. All brake pads 36, 38, 40, 42 are preferably identical parts.

[0052] The brake pads 36, 38, 40, 42 can be applied to the brake rotor 22 by their associated brake piston 32, 34, namely by the respective brake piston 32, 34 being movable between a retracted position and an extended position.

[0053] A drive assembly 44 is provided for moving the two brake pistons 32, 34.

[0054] The drive assembly 44 comprises a first electric motor 46 and a second electric motor 48 separate from the first electric motor 46 (see Fig. 4).

[0055] The first electric motor 46 is associated with the first brake piston 32 to move the first brake piston 32 between the retracted position and the extended position.

[0056] The second electric motor 48 is associated with the second brake piston 34 to move the second brake piston 34 between the retracted position and the extended position.

[0057] Specifically, each electric motor 46, 48 is coupled to one of the brake pistons 32, 34 via a gear unit 49 and a spindle drive 50.

[0058] The spindle drive 50 is, for example, a ball screw drive with a rotatably mounted, electric motor-driven spindle 52, on which the brake piston 32, 34 is mounted. The spindle 52 serves to axially move the brake piston 32, 34. The brake piston 32, 34 forms, in particular, the spindle nut of the spindle drive 50.

[0059] An axial displacement of the brake piston 32, 34 is caused in particular by a rotation of the spindle 52.

[0060] The gear unit 49 is realized, for example, by a planetary gear.

[0061] Fig. 4 shows a perspective view of the vehicle brake 10 from below, looking at the gap 20.

[0062] Based on Fig. 4, the shape of the brake carrier component 16 is explained in detail below.

[0063] The brake carrier component 16 has a central web 54 between the two brake calipers 12, 14, viewed in the direction of movement of the brake pistons 32, 34. The central web 54 is also in the Fig. 1 and Fig. 2 visible.

[0064] Starting from an end of the central web 54 near the wheel hub, two base sections 56, 58 extend away from each other at an obtuse angle from the central web 54.

[0065] A further lateral web 60 extends from the ends of the base sections 56, 58 opposite the central web 54.

[0066] In the exemplary embodiment, the base sections 56, 58 are each formed by two common, angled, spaced-apart legs 62. This makes the space 20 between the legs 62 accessible to the brake rotor 22.

[0067] Of the legs 62, arms 64 are located at the bend (see also Fig. 2) which are part of the central web 54 and which are connected at their free ends by a bridge 66 (see Fig. 1 and Fig. 2) are connected to each other.

[0068] Arms 68, which are part of the lateral webs 60, protrude from the free ends of the legs 62.

[0069] The arms 68 of each lateral web 60 are also connected at their free ends by a bridge 70.

[0070] The brake rotor 22 can be accommodated between the legs 62 and arms 64, 68.

[0071] The legs 62, arms 64, 68 and bridges 66, 70 each represent interconnected struts, whereby the brake carrier component 16 has a particularly high rigidity.

[0072] Between the central web 54 and the lateral webs 60 there is a receiving space 72 (see also Fig. 2) for an associated brake caliper 12, 14.

[0073] In Fig. 4 also shows the arrangement of the electric motors 46, 48 by means of corresponding receiving spaces 74 in the housings 24.

[0074] As in the Fig. 1 and Fig. 2, the first brake caliper 12 and the second brake caliper 14 are guided with one side each on the central web 54 of the brake carrier component 16 and with the opposite side each on an associated one of the two lateral webs 60.

[0075] In addition, in the Fig. 1, Fig. 2 and Fig. 4 that each brake calliper 12, 14 has screw tabs 76 for fastening the housing 24 to the respective brake calliper 12, 14.

[0076] The screw tabs 76 are designed to allow the housings 24 to be mounted in different positions. This allows the arrangement of the housings 24 relative to the brake calipers 12, 14 to be adapted to the respective installation space requirements for different vehicle models.

[0077] Fig. 5 shows a section through the vehicle brake 10, in particular at the level of the bolts 18. This illustrates the guidance of the brake calipers 12, 14 on the central web 54.

[0078] The brake calipers 12, 14 are guided in the same way on the lateral webs 60.

[0079] At least one of the two brake pistons 32, 34, preferably both brake pistons 32, 34, can be assigned a parking lock 77 or parking brake function in addition to the service brake function.

[0080] The parking lock 77 is implemented, for example, by means of a mechanical pawl 78.

[0081] Such a pawl 78 is exemplified in Fig. 6. The pawl engages, for example, a drive gear of the transmission unit 49 and blocks rotation of an output shaft 80 of the respective electric motor 46, 48 and thereby prevents movement of the brake pistons 32, 34.

[0082] In particular, the pawl 78 is mounted in such a way that rotation of an output shaft 80 of the electric motor 46, 48 is blocked in one direction of rotation and released in the opposite direction, whereby readjustment of the braking force is possible when the vehicle brake 10 cools down after the vehicle has been parked.

[0083] However, a parking brake function can also be implemented purely in software by means of the control units 26, 28.

[0084] Fig. 7 shows another vehicle brake 10.

[0085] The vehicle brake 10 according to Fig. 7 differs from the previously described vehicle brake 10 in that there is only one housing 24 in which the control units 26, 28 are accommodated.

[0086] In a further alternative embodiment, it is conceivable that only one control unit is provided in the housing 24, which controls the movement of both brake pistons 32, 34 by correspondingly controlling the electric motors 46, 48.

[0087] In the Fig. 8 and Fig. 9 illustrates another embodiment of a vehicle brake 10. The vehicle brake 10 according to the Fig. 8 and Fig. 9 differs from the previously described embodiments in that only one control unit 26 and only one electric motor 46 are provided.

[0088] The electric motor 46 drives both brake pistons 32, 34, for example, via a differential gear.

[0089] A method for operating an electromechanical vehicle brake 10 is described below, in particular one as shown in the Fig. 1 to 6 illustrated vehicle brake 10 or one in Fig. 7 illustrate vehicle brake 10.

[0090] When operating the vehicle brake 10 in a service braking operation, for example, the two brake pistons 32, 34 are actuated simultaneously in order to achieve a particularly high clamping force of, for example, more than 90 kN.

[0091] In a subsequent service braking operation, the two brake pistons 32, 34 are actuated alternately. This means that only one of the two brake pistons 32, 34 is actuated at a time to initiate a braking operation, which consumes less energy than if both brake pistons 32, 34 were actuated simultaneously.

[0092] The alternating operation serves to wear the brake pads 36, 38, 40, 42 evenly.

[0093] For alternating actuation of the brake pistons 32, 34, two separate electric motors 46, 48 are required, which can drive the brake pistons 32, 34 separately.

[0094] If both brake pistons 32, 34 are assigned a parking lock function in addition to the service brake function, in particular by a pawl 78 and / or by appropriate programming of the control units 26, 28, both brake pistons 32, 34 can be activated to form a parking lock when a vehicle is parked.

[0095] If readjustment of the clamping force is necessary during the storage period, the two brake pistons 32, 34 can be retensioned at different times. This means that one of the two brake pistons 32, 34 always applies a clamping force, ensuring sufficient braking force at all times, even during retensioning.

Claims

[1] Electromechanical vehicle brake (10) with at least one brake calliper (12, 14) in which there is an intermediate space (20) for receiving a brake rotor (22), a first linearly guided brake piston (32), a first brake pad (36) near the piston, which is assigned to the first brake piston (32) and is to be moved by it, a second linearly guided brake piston (34) and a second brake pad (38) near the piston, which is assigned to the second brake piston (34) and is to be moved by it, wherein the brake pads (36, 38) are assigned to a common brake rotor (22) and can be applied to the brake rotor (22) by their assigned brake piston (32, 34), and a third, piston-remote brake pad (40) opposite the first, piston-near brake pad (36) and a fourth, piston-remote brake pad (42) opposite the second, piston-near brake pad (38), and a drive assembly (44) for moving the two brake pistons (32, 34) between a retracted position and an extended position. [2] Electromechanical vehicle brake (10) according to claim 1, characterized by that both brake pistons (32, 34) define service brakes. [3] Electromechanical vehicle brake (10) according to claim 1 or 2, characterized by that the two brake pistons (32, 34) have the same dimensions and / or all brake pads (36, 38, 40, 42) are identical parts. [4] Electromechanical vehicle brake (10) according to one of the preceding claims, characterized by that the vehicle brake (10) has a brake carrier component (16) which can be fastened to a vehicle axle and on which the at least one brake calliper (12, 14) is guided. [5] Electromechanical vehicle brake (10) according to claim 4, characterized byin that the vehicle brake (10) has a first brake calliper (12), to which the first brake piston (32) is assigned, and a second brake calliper (14) separate from the first brake calliper (12), to which the second brake piston (34) is assigned, wherein the first brake calliper (12) and the second brake calliper (14) are fastened to the brake carrier component (16). [6] Electromechanical vehicle brake (10) according to claim 5, characterized by that the brake callipers (12, 14) are identical parts. [7] Electromechanical vehicle brake (10) according to one of claims 4 to 6, characterized byin that the brake carrier component (16), viewed in the direction of movement of the brake pistons (32, 34), has a central web (54) between the two brake callipers (12, 14), wherein, starting from an end of the central web (54) near the wheel hub, two base sections (56, 58) extend away from one another at an obtuse angle from the central web (54), wherein a further lateral web (60) extends from each of the ends of the base sections (56, 58) opposite the central web (54), wherein a receiving space (72) for an associated brake calliper (12, 14) is formed between the central web (54) and the lateral webs (60). [8] Electromechanical vehicle brake (10) according to claim 7, characterized byin that the base sections (56, 58) are formed by two common, angled, spaced-apart legs (62), arms (64) projecting from the legs (62) at the angle, which arms are part of the central web (54) and are connected to one another at their free ends by a bridge (66), and arms (68) projecting from the free ends of the legs (62) are part of the lateral webs (60), and the arms (68) of each lateral web (60) are connected at their free ends by a bridge (70), the brake rotor (22) being able to be accommodated between the legs (62) and arms (64, 68). [9] Electromechanical vehicle brake (10) according to one of claims 5 to 8, characterized by that the first brake calliper (12) and the second brake calliper (14) are each guided with one side on the central web (54) of the brake carrier component (16) and with the opposite side on an associated one of the two lateral webs (60). [10] Electromechanical vehicle brake (10) according to one of claims 5 to 9, characterized by that the first brake calliper (12) and the second brake calliper (14) are fastened to the front side of the brake carrier component (16). [11] Electromechanical vehicle brake (10) according to one of the preceding claims, characterized by in that the drive assembly (44) has a first electric motor (46) and a second electric motor (48) separate from the first electric motor (46), wherein the first electric motor (46) is assigned to the first brake piston (32) in order to move the first brake piston (32) between the retracted position and the extended position, and the second electric motor (48) is assigned to the second brake piston (34) in order to move the second brake piston (34) between the retracted position and the extended position. [12] Electromechanical vehicle brake (10) according to claim 11, characterized byin that the drive assembly (44) has a first control unit (26) and a second control unit (28) separate from the first control unit (26), wherein the first control unit (26) is configured to control the first electric motor (46) and the second control unit (28) is configured to control the second electric motor (48), wherein the control units (26, 28) each have their own electronic connection (30). [13] Electromechanical vehicle brake (10) according to one of the preceding claims, characterized by that at least one of the two brake pistons (32, 34) is assigned a parking lock (77) or parking brake function in addition to the service brake function. [14] Method for operating an electromechanical vehicle brake (10) according to one of the preceding claims, characterized by that the two brake pistons (32, 34) are actuated simultaneously or alternately during a service braking operation. [15] Method for operating an electromechanical vehicle brake (10) according to claim 14, wherein both brake pistons (32, 34) are assigned a parking lock function in addition to the service brake function, wherein in a first method step when a vehicle is parked both brake pistons (32, 34) are activated to form a parking lock and wherein during the parking period the two brake pistons (32, 34) are retensioned with a time delay.

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