Actuator assembly for an electromechanical vehicle brake

Abstract

An actuator assembly (10) is proposed for an electromechanical vehicle brake, comprising a brake caliper (12) in which an intermediate space (14) for a brake rotor (16) is formed, wherein a brake pad (18) that can be applied to the brake rotor (16) is arranged in the intermediate space (14), a spindle drive (20) that has a spindle sleeve (22), a spindle nut (24) and an electric motor-driven drive shaft (26) for adjusting the spindle nut (24) via the spindle sleeve (22) in the axial direction (A), wherein the spindle nut (24) can be moved between an extended and a retracted position by axial adjustment and the drive shaft (26) is coupled to the spindle sleeve (22) via a gear (28), and wherein the gear (28) is arranged at least partially within the spindle nut (24) and / or the spindle sleeve (22) in the axial direction (A).

Description

[0001] The invention relates to an actuator assembly for an electromechanical vehicle brake.

[0002] Actuator assemblies in vehicle brakes are used to apply a brake pad to a brake rotor. For this purpose, the actuator assembly typically includes a spindle drive with a spindle nut and an electric motor-driven spindle for axially moving the spindle nut. An axial feed force for applying the brake pad to the brake rotor is transmitted from the spindle nut to the brake pad.

[0003] The electric motor, which drives the spindle drive, is arranged eccentrically to the drive axis of the spindle drive with respect to its drive axis.

[0004] In order to couple the electric motor with the spindle drive, a single-stage gearbox is provided between the electric motor and the spindle and, in addition, a planetary gearbox is provided on the spindle in order to provide a corresponding axial feed force for applying the brake pad.

[0005] The installation space conditions in the area of ​​actuator assemblies for electromechanical vehicle brakes are usually very limited.

[0006] Consequently, the application area of ​​actuator assemblies always depends on their installation space requirements, whereby a relatively high installation space requirement of an actuator assembly is disadvantageous.

[0007] It is therefore the object of the invention to provide an actuator assembly for an electromechanical vehicle brake which has a particularly small installation space requirement.

[0008] The object is achieved according to the invention by an actuator assembly for an electromechanical vehicle brake, with a brake calliper in which an intermediate space for a brake rotor is formed, wherein a brake pad which can be applied to the brake rotor is arranged in the intermediate space, a spindle drive which has a spindle sleeve, a spindle nut and an electric motor-driven drive shaft for adjusting the spindle nut via the spindle sleeve in the axial direction, wherein the spindle nut can be moved between an extended and a retracted position by axial adjustment, wherein the drive shaft is coupled to the spindle sleeve via a gear, and wherein the gear is arranged at least partially within the spindle nut and / or the spindle sleeve in the axial direction.

[0009] The basic idea of ​​the invention is to reduce the installation length of the actuator assembly by utilizing the unused space within the spindle nut and / or spindle sleeve to at least partially arrange the gear unit, which is required to drive the spindle drive via an electric motor, within the spindle nut and / or spindle sleeve. The spindle sleeve sits within the spindle nut and drives it via the spindle drive, for example, the interposed balls.

[0010] Consequently, the installation space occupied by the actuator assembly is reduced, so that installation space can be saved and at the same time the available installation space within the actuator assembly itself is used more effectively.

[0011] In particular, the term "gearbox" refers only to the gears or toothed sections that form the gear box, without taking into account, for example, the shafts or sleeves on which the gears or toothed sections are mounted. These can optionally be located partially or entirely outside the spindle nut and / or spindle sleeve.

[0012] The gearbox can be a single-stage gearbox.

[0013] A single-stage gearbox allows the implementation of a simple gearbox with few components and still allows for an appropriate gear ratio to be provided between the electric motor and the spindle drive.

[0014] In addition, single-stage gearboxes can be designed to be particularly robust.

[0015] According to one aspect, the gear is a cycloidal gear comprising an internally toothed pin ring and an externally toothed cam or cycloidal disk that mesh with each other, as well as an eccentric shaft with a bearing section and an eccentric section, the central longitudinal axis of which is radially offset from a rotational axis of the bearing section by an eccentricity e greater than zero. The cam is rotatably mounted on the eccentric section about the central longitudinal axis. Cycloidal gears are among the high-reduction gears, which allows for savings in axial length as well as the number of components and thus mass.

[0016] The bolt ring and the cam disc are designed in particular with a tooth number difference of one, whereby the bolt ring has one tooth more than the cam disc.

[0017] Furthermore, it can be provided that the bolt ring is non-rotatably connected to a housing of the actuator assembly and arranged coaxially to the rotational axis of the bearing section. This makes the transmission particularly compact and effective.

[0018] In one embodiment, the eccentric shaft is mounted so that it can rotate about the axis of rotation via a front pivot bearing in the housing and / or via a rear pivot bearing in the spindle sleeve, thus making it particularly space-saving.

[0019] Furthermore, the cam disk can be coupled to the spindle sleeve via several output pins. Each output pin extends axially into a circular bearing opening in the cam disk, thus ensuring an effective and space-efficient torque-transmitting connection between the cam disk and the spindle sleeve.

[0020] The output pins can be fastened in an axial section of the spindle sleeve, so that additional connecting components can be omitted.

[0021] In addition, the axial section can have an outer circumferential surface with an outer diameter that is smaller than the maximum outer diameter of the spindle sleeve, making it particularly material-efficient.

[0022] According to one embodiment, the spindle drive has several annular axial bearings, via which the spindle sleeve is axially supported on the pin ring. The axial bearings are each centered or coaxially arranged on their inner circumferential surface on the outer circumferential surface of the spindle sleeve relative to the rotational axis of the bearing section. This allows the actuator assembly to have a particularly small number of individual parts and a compact design.

[0023] According to a further embodiment, in at least one position of the spindle nut, the bolt ring and / or the axial bearings are arranged at least partially within the spindle nut in the axial direction, whereby the actuator assembly has a particularly short axial length.

[0024] Furthermore, the drive shaft can be coupled to a motor shaft of an electric motor without a gear or can be coupled to a motor shaft of an electric motor via a gear unit arranged completely outside the spindle nut and / or the spindle sleeve, in particular a single-stage gear unit.

[0025] Accordingly, no additional gear is required, reducing manufacturing costs and the complexity of the actuator assembly.

[0026] Alternatively, only a single-stage gearbox is required, which can be provided particularly easily and cost-effectively.

[0027] The invention is described below with reference to an embodiment illustrated in the accompanying drawings, in which: - Fig. 1 a sectional view of an actuator assembly according to the invention with a spindle nut in a retracted position, - Fig. 2 a partial section of a part of a spindle drive with a cycloid gear of the actuator assembly according to the invention in a perspective view; - Fig. 3 in a top view the cycloidal gear from Fig. 2; and - Fig. 4 the part of the spindle drive with the cycloid gear from Fig. 2 in an exploded view.

[0028] Fig. 1 shows an actuator assembly 10 for an electromechanical vehicle brake.

[0029] The actuator assembly 10 comprises a brake caliper 12 in which a space 14 for a brake rotor 16 is formed.

[0030] In the intermediate space 14, at least one brake pad 18 is arranged on each side of the brake rotor 16, which can be applied to the brake rotor 16.

[0031] Furthermore, the actuator assembly 10 comprises a spindle drive 20, which in the exemplary embodiment is a ball screw drive, with a rotatably mounted, electric motor-driven spindle sleeve 22, on which a spindle nut 24 for applying the brake pad 18 to the brake rotor 16 is mounted on the outer casing.

[0032] Furthermore, a drive shaft 26 is provided which serves to drive the spindle sleeve 22, wherein the spindle nut 24 can in turn be adjusted axially, ie in or against the axial direction A, via the spindle sleeve 22.

[0033] The spindle nut 24 is adjustable by axial displacement between an extended and a retracted position and is linearly guided in the brake caliper 12. The spindle sleeve 22 and spindle nut are coupled to each other via a recirculating ball system, so that when the spindle sleeve 22 rotates, the non-rotatable spindle nut 24 is axially adjusted.

[0034] The spindle nut 24 of the spindle drive 20 represents in particular a brake piston.

[0035] The drive shaft 26 is coupled to the spindle sleeve 22 via a gear 28.

[0036] The actuator assembly 10 further has a housing 30 within which the spindle drive 20 is accommodated.

[0037] The housing 30 is here connected in one piece to the brake caliper 12.

[0038] In this context, the spindle drive 20 is arranged axially between the brake pads 18 and a bottom wall 32 of the housing 30, against which the spindle drive 20 is supported counter to the axial direction A when the spindle nut 24 presses the brake pad 18 against the brake rotor in order to actuate the electromechanical vehicle brake.

[0039] In the embodiment shown, the gear 28 is a single-stage gear in the form of a cycloidal gear 34, the structure of which is described below with reference to the Fig. 2 to 4.

[0040] The cycloidal gear 34 has an internally toothed pin ring 36 and an externally toothed cam disc 38, which are toothed together, as well as an eccentric shaft 40 with a bearing section 42 and an eccentric section 44.

[0041] The bolt ring 36 is torsionally fixed to the base wall 32 (see Fig. 1) of the housing 30.

[0042] For example, the bolt ring 36 is designed in one piece.

[0043] The external toothing 46 of the cam disc 38 has a curved cycloid contour (see Fig. 3), which is composed of identical cam sections machined with a constant pitch on the outer circumference of the cam disc 38. The profile of each cam section is designed as a shortened epicycloid, with each cam section being considered a tooth.

[0044] The internal toothing 48 of the pin ring 36 has a rolling curve contour composed of identical curved sections machined with a constant pitch on the inner circumference of the pin ring 36. The profile of each rolling curve section is circular, with each rolling curve section being considered a tooth.

[0045] Alternatively, the internal toothing 48 of the bolt ring 36 can have the cycloid contour and the external toothing 46 of the cam disk 38 can have the rolling curve contour.

[0046] The external toothing 46 and the internal toothing 48 are designed with a tooth number difference of one, wherein the internal toothing 48 has one tooth more than the external toothing 46.

[0047] The eccentric shaft 40 is rotatable about a rotation axis R (see Fig. 2) is rotatably mounted in the housing 30, which forms a central longitudinal axis of the bearing section 42. Thus, the bearing section 42 is also rotatably mounted in the housing 30 about the rotation axis R.

[0048] For this purpose, the eccentric shaft 40 is mounted on a front pivot bearing 50 in the bottom wall 32 (see Fig. 1) and is mounted in the spindle sleeve 22 via a rear pivot bearing 52 so that it can rotate about the rotation axis R.

[0049] The rotation axis R of the eccentric shaft 40 is congruent or identical to the rotation axis S of the spindle sleeve 22.

[0050] Furthermore, the rotation axis R is coaxial with the internal toothing 48 (see Fig. 3) of the bolt ring 36.

[0051] The eccentric section 44 (see Fig. 2) has a central longitudinal axis M which is radially offset from the rotation axis R by an eccentricity e greater than zero, ie it runs parallel to it at a distance e.

[0052] The cam disc 38 is mounted on the eccentric section 44 arranged eccentrically to the rotation axis R of the eccentric shaft 40 via a further pivot bearing 54 so as to be rotatable about the central longitudinal axis M.

[0053] For this purpose, the cam disc 38 has a central, circular-cylindrical passage, the central longitudinal axis of which is arranged coaxially to the external toothing 46.

[0054] The pivot bearings 50, 52, 54, for example, are designed as rolling bearings.

[0055] The cam disc 38 is coupled to the spindle sleeve 22 via several output pins 56 in a torque-transmitting manner, for example seven output pins 56 (see Fig. 3).

[0056] For this purpose, the cam disc 38 has a corresponding number of bearing openings 58, which are in permanent engagement with the output pins 56 via rolling sleeves 60 and carry them in the tangential direction when the cam disc 38 rotates in the circumferential direction U.

[0057] The rolling sleeves 60 are rotatably mounted on the output pin 56 and are in rolling contact with the bearing openings 58 with their outer surface, thus reducing friction.

[0058] The diameters of the bearing openings 58 are, for example, twice the amount of the eccentricity e larger than the outer diameters of the rolling sleeves 60.

[0059] Furthermore, the bearing openings 58 and the output pins 56 are located on pitch circle diameters of the same size.

[0060] The output pins 56 are connected to the spindle sleeve 22 in a rotationally fixed manner, for example via receiving openings 62 (see Fig. 2), in which the output pins 56 are pressed in.

[0061] In principle, the output pins 56 can be connected to the spindle sleeve 22 in any manner in a rotationally fixed manner.

[0062] The receiving openings 62 are arranged on a pitch circle whose center coincides with the rotation axis S of the spindle sleeve 22.

[0063] In the present embodiment, the receiving openings 62 are arranged in an axial section 64 of the spindle sleeve 22, which adjoins an axial end 66 of the spindle sleeve 22 facing the cam disk 38.

[0064] In order to absorb the reaction force acting on the spindle sleeve 22 when the spindle nut 24 is driven in the axial direction A, the spindle drive 20 has an axial bearing package 68 which bears against the bolt ring 36 opposite to the axial direction A.

[0065] In the illustrated embodiment, the thrust bearing package 68 has three annular thrust bearing assemblies 70, 72, 74.

[0066] The first axial bearing unit 70 is a rotationally symmetrical spherical axial bearing disk 76, the second axial bearing unit 72 is a cylindrical roller thrust bearing 78, and the third axial bearing unit 74 is a planar axial bearing disk 80.

[0067] The spherical axial bearing disc 76 lies in axial direction A on an axial end face 82 (see Fig. 2) of the spindle sleeve 22.

[0068] The axial end face 82 is designed as a convex contact surface and the complementary contact surface of the spherical axial bearing disc 76 is correspondingly concave and thus forms a spherical contact zone 84.

[0069] On the opposite side, the spherical axial bearing disc 76 has a planar contact surface on which rolling elements of the axial cylindrical roller bearing 78 roll.

[0070] The spherical contact zone 84 allows angular compensation between spindle sleeve 22 and brake calliper 22 and ensures uniform contact pressure on the rolling elements of the axial cylindrical roller bearing 78 when the brake calliper 12 bends under load.

[0071] The rolling elements of the axial cylindrical roller bearing 78 roll on the opposite side on the planar axial bearing disc 80, which extends over a planar contact zone 86 (see Fig. 2) is supported on the bolt ring 36 and is centered thereon via a shoulder 88.

[0072] Furthermore, the axial bearing units 70, 72, 74 are each centered on their inner circumferential surface on the outer circumferential surface 90 of the axial section 64 of the spindle sleeve 22 and are thus arranged coaxially to the rotation axis R.

[0073] In this context, the outer circumferential surface 90 has an outer diameter d (see Fig. 2), which is smaller than the maximum outer diameter D of the spindle sleeve 22.

[0074] In this way, an annular gap 92 is formed in which the axial bearing units 70, 72, 74 are arranged in the radial direction between the axial section 64 and the spindle nut 24 when the spindle nut 24 is in a retracted position (see Fig. 2) is.

[0075] Furthermore, the bolt ring 36 projects beyond the open end of the spindle nut 24 into a cavity 94 within the spindle nut 24 and is thus arranged partially within the spindle nut 24 in the axial direction A when the spindle nut 24 is in the retracted position.

[0076] In the retracted position, the cam disc 38 is also partially arranged in the cavity 94 within the spindle nut 24.

[0077] Consequently, the gear 28 is arranged at least partially within the spindle nut 24 in the axial direction A when the latter is in the retracted position.

[0078] Furthermore, in the retracted position, the spindle sleeve 22 is completely arranged in the cavity 94 within the spindle nut 24.

[0079] In principle, the gear 28 can be arranged completely within the spindle nut 24 in at least one position of the spindle nut 24 in the axial direction A, for example if the bottom wall 32 extends in the form of a pedestal in the axial direction A into the cavity 94, so that the bolt ring 36 is arranged completely within the spindle nut 24 in the axial direction A.

[0080] Additionally or alternatively, the gear 28 can be arranged at least partially within the spindle sleeve 22 in the axial direction A.

[0081] In this context, only the gears or toothed sections can be regarded as gears, without taking into account the shafts or sleeves on which the gears or toothed sections are provided.

[0082] In order to drive the spindle drive 20 and to move the spindle nut 24 between the retracted position and the extended position, the actuator assembly 10 has an electric motor 96 with a motor shaft.

[0083] The motor shaft is coupled to the drive shaft 26 via a gear unit 98, wherein the gear unit 98 is arranged completely outside the spindle sleeve 22.

[0084] Alternatively, it is conceivable that the drive shaft 26 is coupled to the motor shaft of the electric motor 96 without a gear, so that the motor shaft is arranged coaxially to the drive shaft 26.

[0085] If the spindle nut 24 is now to be adjusted in the axial direction A, the drive shaft 26 is set in rotation.

[0086] This imparts rotational power to the eccentric shaft 40. Since the cam disc 38 rotates eccentrically outside the rotational axis R and the cam disc 38 is toothed in the pin ring 36, the cycloid contour of the cam disc 38 rolls on the rolling curve contour of the stationary pin ring 36. The cam disc 38 is coupled to the spindle sleeve 22 via the output pins 56 and imparts rotational power to the spindle sleeve, thereby axially adjusting the spindle nut 24 accordingly. The eccentric shaft 40 and the spindle sleeve 22 rotate in opposite directions.

[0087] In this way, an actuator assembly 10 for an electromechanical vehicle brake is provided which is designed to be particularly compact, in particular in the axial direction A.

Claims

[1] Actuator assembly (10) for an electromechanical vehicle brake, comprising a brake calliper (12) in which an intermediate space (14) for a brake rotor (16) is formed, wherein a brake pad (18) is arranged in the intermediate space (14) and can be applied to the brake rotor (16), a spindle drive (20) having a spindle sleeve (22), a spindle nut (24) and an electric motor-driven drive shaft (26) for adjusting the spindle nut (24) via the spindle sleeve (22) in the axial direction (A), wherein the spindle nut (24) can be moved between an extended and a retracted position by axial adjustment, wherein the drive shaft (26) is coupled to the spindle sleeve (22) via a gear (28), and wherein the gear (28) is arranged at least partially within the spindle nut (24) and / or the spindle sleeve (22) in the axial direction (A). [2] Actuator assembly (10) according to claim 1, characterized bythat the gearbox (28) is a single-stage gearbox (28). [3] Actuator assembly (10) according to claim 2, characterized by that the gear (28) is a cycloidal gear (34), wherein the cycloidal gear (34) has an internally toothed bolt ring (36) and an externally toothed cam disc (38) which are in engagement with one another, and an eccentric shaft (40) with a bearing section (42) and an eccentric section (44), the central longitudinal axis (M) of which is radially offset from a rotational axis (R) of the bearing section (42) by an eccentricity e greater than zero, wherein the cam disc (38) is rotatably mounted on the eccentric section (44) about the central longitudinal axis (M). [4] Actuator assembly (10) according to claim 3, characterized by that the bolt ring (36) is connected in a rotationally fixed manner to a housing (30) of the actuator assembly (10) and is arranged coaxially to the rotation axis (R) of the bearing section (42). [5] Actuator assembly (10) according to claim 4, characterized by that the eccentric shaft (40) is rotatably mounted about the rotation axis (R) via a front pivot bearing (50) in the housing (30) and / or via a rear pivot bearing (52) in the spindle sleeve (22). [6] Actuator assembly (10) according to one of claims 3 to 5, characterized by that the cam disc (38) is drivingly coupled to the spindle sleeve (22) via a plurality of output pins (56), each output pin (56) extending axially into a circular bearing opening (58) of the cam disc (38). [7] Actuator assembly (10) according to claim 6, characterized by that the output pins (56) are fastened in an axial section (64) of the spindle sleeve (22). [8] Actuator assembly (10) according to claim 7, characterized by that the axial section (64) has an outer circumferential surface (90) with an outer diameter (d) which is smaller than the maximum outer diameter (D) of the spindle sleeve (22). [9] Actuator assembly (10) according to claim 8, characterized by that the spindle drive (20) has a plurality of annular axial bearings (70, 72, 74) via which the spindle sleeve (22) is axially supported on the bolt ring (36), wherein the axial bearings (70, 72, 74) are each centered on their inner circumferential surface on the outer circumferential surface (90) of the spindle sleeve (22) relative to the rotation axis (R) of the bearing section (42). [10] Actuator assembly (10) according to one of claims 3 to 9, characterized by that in at least one position of the spindle nut (24) the bolt ring (36) and / or the axial bearings (70, 72, 74) are arranged at least partially within the spindle nut (24) in the axial direction (A). [11] Actuator assembly (10) according to one of the preceding claims, characterized bythat the drive shaft (26) is coupled to a motor shaft of an electric motor (96) without a gear, or that the drive shaft (26) is coupled to a motor shaft of an electric motor (96) via a gear unit (98) arranged entirely outside the spindle sleeve (22), in particular a single-stage gear unit.

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