Actuator assembly for an electromechanical vehicle brake

Abstract

An actuator assembly (10) for an electromechanical vehicle brake has a brake caliper (12), in which an intermediate space (14) for a brake rotor (16) is formed, and a spindle drive (20), which has a spindle sleeve (22), a spindle nut (24) and an electromotively driven drive shaft (26) for adjusting the spindle nut (24) in the axial direction (A) via the spindle sleeve (22). The drive shaft (26) is coupled to the spindle sleeve (22) via a gear mechanism (28) which is arranged at least partially within the spindle sleeve (22) in the axial direction (A). Furthermore, a ball return (102) of the spindle drive (20) is integrated in the spindle sleeve (22).

Description

[0001] Actuator assembly for an electromechanical vehicle brake

[0002] The invention relates to an actuator assembly for an electromechanical vehicle brake.

[0003] 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.

[0004] 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.

[0005] 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 be able to provide a corresponding axial feed force for applying the brake pad.

[0006] The installation space conditions in the area of ​​actuator assemblies for electromechanical vehicle brakes are usually very limited.

[0007] 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.

[0008] 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.

[0009] The object is achieved according to the invention by an actuator assembly for an electromechanical vehicle brake, comprising a brake caliper in which an intermediate space for a brake rotor is formed, wherein a brake pad that 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. The drive shaft is coupled to the spindle sleeve via a gear which is arranged at least partially within the spindle sleeve in the axial direction. Furthermore, at least one ball return of the spindle drive is integrated into the spindle sleeve.

[0010] The basic idea of ​​the invention is to reduce the installation length of the actuator assembly by utilizing the unused space within the spindle sleeve to at least partially accommodate the gearing required to drive the spindle drive via an electric motor within the spindle sleeve. The spindle sleeve sits within the spindle nut and drives it via a recirculating ball system of the spindle drive, i.e., the intermediate balls. Furthermore, the spindle sleeve is used to provide the ball return of the spindle drive, whereby the ball return runs radially within the intermediate balls that drive the spindle nut, and not outside, as would be the case with a ball return integrated into the spindle nut. This allows the spindle nut to be smaller yet more stable.

[0011] 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.

[0012] In particular, the term "gearbox" refers only to the gears or toothed sections that form the gear box, without considering, 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 sleeve.

[0013] According to one aspect, the spindle sleeve has at least two turns, each associated with its own ball circuit, whereby the spindle drive can also effectively transmit large forces.

[0014] For the purposes of the invention, the windings refer, in particular, exclusively to windings that are part of at least one ball circuit or part of the ball circuit system. In one embodiment, the ball return integrated into the spindle sleeve forms a common return for at least two ball circuits, i.e., although the windings are separate, the ball return channels are shared channels for both ball circuits. The ball return can also act jointly for all windings.

[0015] In an alternative embodiment, at least one additional ball return of the spindle drive is integrated into the spindle sleeve. Each of the ball return channels integrated into the spindle sleeve forms a return for at least one of the windings. This makes the spindle drive particularly compact. In particular, two or more separate ball circuits are provided that do not share common tracks or channels. In the case of such separate ball circuits, they are preferably arranged with an axial and angular offset from one another.

[0016] Each ball return can be provided with a return channel and two deflectors. The deflectors are designed to guide the balls into or out of the return channel, which guides them from the end of the ball circuit to the beginning of the corresponding ball circuit.

[0017] The spindle sleeve can have a spindle sleeve insert for each ball return, which is attached to a spindle sleeve body of the spindle sleeve. The spindle sleeve insert contains the return channel and the two deflectors of the corresponding ball return. The spindle sleeve is thus designed in several parts, while the ball return channels are each formed by a spindle sleeve insert. This design has the advantage that the spindle sleeve can be manufactured with little effort.

[0018] Alternatively, the spindle sleeve can have a spindle sleeve insert for each deflector, which is attached to a spindle sleeve body of the spindle sleeve. The spindle sleeve insert then has the corresponding deflector. The spindle sleeve and the ball return lines are thus each designed in several parts. This allows the spindle sleeve inserts to be designed particularly compactly. Furthermore, each return channel can be formed in the spindle sleeve body, which makes the ball return lines particularly simple.

[0019] In one embodiment, the spindle sleeve has a hollow space and internal gearing of the gear that defines the hollow space. The internal gearing is either integral with the spindle sleeve or part of a ring gear that is non-rotatably connected to the spindle sleeve. By integrating the internal gearing into the spindle sleeve, the gearing and spindle drive are designed to be particularly compact.

[0020] According to one aspect, the internal toothing extends only over a part of the total axial length of the cavity, which facilitates the production of the internal toothing.

[0021] In another embodiment, a gear element of the gearbox is mounted in the spindle sleeve via a rolling bearing. This makes the spindle drive and gearbox particularly space-efficient.

[0022] The transmission element can be an input pinion shaft or a planetary carrier, which can be effectively supported by the roller bearing. For the purposes of the invention, an input pinion shaft is a shaft to which an input pinion is rotationally fixedly coupled.

[0023] Furthermore, it can be provided that only a single rotatably mounted gear element of the transmission, in particular a gear element rotatably mounted about its own axis of rotation, is arranged in the power flow path between the rotatably mounted drive shaft and the rotatably mounted spindle sleeve. The gear element is designed as a single piece, i.e., it is formed in one piece, or all sections of the gear element are rigidly connected to one another. The power flow path relates to the transmission of torque from the drive-side drive shaft to the output-side spindle sleeve. This makes the transmission particularly simple and cost-effective.

[0024] According to one embodiment, the gear unit is a reduction gear unit in the form of a Wolfrom gear unit, an eccentric gear unit, or a cycloidal gear unit. These types of gear units are among the high-reduction gear units, which allow for savings in axial length and the number of components, thus reducing mass.

[0025] Furthermore, the gear can be arranged at least partially within the spindle nut in the axial direction, in particular in the retracted position, in order to reduce the installation length of the actuator assembly.

[0026] According to a further embodiment, the spindle sleeve rests against a spherical axial bearing disk via an axially tapered end face. This ensures that the spindle sleeve is reliably centered.

[0027] In this case, the axially tapered end face of the spindle sleeve can be convex in order to center the spindle sleeve particularly effectively.

[0028] Additionally or alternatively, the spherical axial bearing disc can be arranged at least partially within the spindle nut in the axial direction, in particular in the retracted position, in order to reduce the installation length of the actuator assembly.

[0029] In one embodiment, both axial ends of the spindle sleeve have a central opening. This means that the spindle sleeve has no shaft and is thus a shaftless spindle sleeve, which has a particularly low mass and a particularly large cavity.

[0030] The object is further achieved according to the invention by an actuator assembly for an electromechanical vehicle brake, comprising a brake caliper in which an intermediate space for a brake rotor is formed, wherein a brake pad that 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. The drive shaft is coupled to the spindle sleeve via a gear which is arranged at least partially within the spindle sleeve in the axial direction. Furthermore, the spindle sleeve has a cavity and an internal gearing of the gear that delimits the cavity.The internal gearing is either integral with the spindle sleeve or part of a ring gear that is non-rotatably connected to the spindle sleeve. By integrating the internal gearing into the spindle sleeve, the gearbox and spindle drive are designed to be particularly compact.

[0031] The object is further achieved according to the invention by an actuator assembly for an electromechanical vehicle brake, comprising a brake caliper in which a space for a brake rotor is formed, wherein a brake pad that can be applied to the brake rotor is arranged in the 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. The drive shaft is coupled to the spindle sleeve via a gear that is arranged at least partially within the spindle sleeve in the axial direction. Furthermore, a gear element of the gear is mounted in the spindle sleeve via a rolling bearing. The spindle drive with the gear is thus designed to be particularly space-efficient.

[0032] The object is further achieved according to the invention by an actuator assembly for an electromechanical vehicle brake, comprising a brake caliper in which an intermediate space for a brake rotor is formed, wherein a brake pad that 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. The drive shaft is coupled to the spindle sleeve via a gear that is arranged at least partially within the spindle sleeve in the axial direction. Furthermore, only a single rotatably mounted gear element of the gear is arranged in the force flow path between the rotatably mounted drive shaft and the rotatably mounted spindle sleeve.The gear element is designed as a single piece, meaning it is constructed in one piece or all sections of the gear element are rigidly connected to one another. The power flow path relates to the transmission of torque from the input-side drive shaft to the output-side spindle sleeve. This makes the gear element particularly simple and compact. The four variants mentioned above, which are considered separate inventions, can also be used in any combination with one another, including in combination with the features specified in the subclaims.

[0033] The invention is described below with reference to an embodiment illustrated in the accompanying drawings, in which:

[0034] Figure 1 shows a sectional view of an actuator assembly according to the invention with a Wolfrom gear,

[0035] Figure 2 shows a perspective view of a spindle drive of the actuator assembly from Figure 1,

[0036] Figure 3 shows an exploded view of the spindle drive from Figure 2,

[0037] Figure 4 shows a sectional view of a spindle drive of the actuator assembly from Figure 1 according to a variant,

[0038] Figure 5 shows a perspective view of a spindle sleeve insert of the spindle drive from Figure 2,

[0039] Figure 6 shows a sectional view of the spindle sleeve insert from Figure 5,

[0040] Figure 7 shows an exploded view of a spindle drive of the actuator assembly from Figure 1 according to a further variant,

[0041] Figure 8 shows a side view of the spindle drive from Figure 7,

[0042] Figure 9 shows the spindle drive in a sectional view along the plane IX - IX in Figure 8,

[0043] Figure 10 shows an exploded view of a spindle drive of the actuator assembly from Figure 1 according to a further variant,

[0044] Figure 11 shows a sectional view of an actuator assembly according to the invention according to a variant with an eccentric gear, and

[0045] - Figure 12 shows a sectional view of an actuator assembly according to the invention according to a variant with a cycloidal gear.

[0046] Figure 1 shows an actuator assembly 10 for an electromechanical vehicle brake. The actuator assembly 10 comprises a brake caliper 12 in which a space 14 for a brake rotor 16 is formed.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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 the spindle nut 24 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.

[0051] The spindle nut 24 of the spindle drive 20 represents in particular a brake piston.

[0052] The drive shaft 26 is coupled to the spindle sleeve 22 via a gear 28.

[0053] The actuator assembly 10 further has a housing 30 within which the spindle drive 20 is accommodated.

[0054] The housing 30 is here connected in one piece to the brake caliper 12.

[0055] 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 to actuate the electromechanical vehicle brake. The bottom wall 32 has an annular section 34 that extends in the axial direction A into a cavity 36 of the spindle nut 24 when the spindle nut 24 is in a retracted position.

[0056] In this context, Figure 1 shows the retracted position of the spindle nut.

[0057] In the illustrated embodiment, the gear 28 is a multi-stage planetary gear in the form of a Wolfrom gear 38.

[0058] In an alternative embodiment, the transmission 28 may be a single-stage planetary transmission.

[0059] The gear 28 has a pinion 40 which is non-rotatably connected to the drive shaft 26.

[0060] In addition, the gear 28 comprises an internal toothing 42 which is formed on the inside of the spindle sleeve 22.

[0061] The internal toothing 42 extends only over a part of the total axial length of the cavity 37 of the spindle sleeve 22.

[0062] In this context, only the gears or toothed sections are considered to be gears, without taking into account the shafts or sleeves on which the gears or toothed sections are provided.

[0063] The internal toothing 42 is formed integrally with the spindle sleeve 22.

[0064] Alternatively, the internal toothing 42 can be part of a ring gear that is connected to the spindle sleeve 22 in a rotationally fixed manner, for example by pressing.

[0065] In this Wolfrom gear 38, the pinion 40 is arranged coaxially to the spindle nut 24 and spindle sleeve 22, so that a sun gear is formed by the pinion 40.

[0066] The internal gearing 42 on the spindle sleeve 22 is arranged coaxially with the pinion 40 and forms a ring gear. Furthermore, a ring gearing 44 is part of the Wolfrom gear 38 and is provided on a ring gear sleeve 46.

[0067] The ring gear sleeve 46 extends into the interior of the spindle sleeve 22. Consequently, the ring gear sleeve 46 has a region that axially overlaps with the cavity 37 of the spindle sleeve 22.

[0068] The drive shaft 26 is mounted via rolling bearings 48 within the ring gear sleeve 46.

[0069] The ring gear sleeve 46 is coupled in a rotationally fixed manner to the housing 30 or the brake caliper 12.

[0070] Furthermore, the transmission 28 comprises planetary gears 50 of a first stage and planetary gears 52 of a second stage which are rotationally coupled thereto.

[0071] A planet carrier 54 is provided to support the planet gears 50, 52.

[0072] The planet carrier 54, which forms a transmission element 56 of the transmission 28, is mounted on the axial side facing the brake rotor 16 via rolling bearings 58 in the spindle sleeve 22.

[0073] On the opposite side, the planet carrier 54 is mounted in the ring gear sleeve 46.

[0074] In this context, the spindle sleeve 22 has a central opening 64 at its first axial end 60 and at its opposite second axial end 62, and is thus formed without a shaft. In other words, the cavity 37 extends from the first axial end 60 to the second axial end 62 and thus completely through the spindle sleeve 22 in the axial direction A.

[0075] The planetary gears 50 of the first stage mesh with the teeth of the pinion 40 and the internal gearing 42. The planetary gears 50 of the second stage mesh with the ring gear teeth 44 of the ring gear sleeve 46.

[0076] If the spindle nut 24 is now to be adjusted in the axial direction A, the drive shaft 26 is rotated. This causes the pinion 40 to rotate, driving the planetary gears 50 of the first stage, which would engage the ring gear teeth 44 of the most rotated ring gear sleeve 46.

[0077] Since each of the planetary gears 50 of the first stage is rotationally coupled to a respective planetary gear 52 of the second stage, the planetary gears 52 also perform a rotational movement.

[0078] The planetary gears 52 of the second stage engage with the internal toothing 42, so that a force flow path exists between the drive shaft 26 and the spindle sleeve 22.

[0079] The planetary gears 50 of the first stage and the planetary gears 52 of the second stage form a gear member 66, which is arranged as the only rotatably mounted gear member 66 in the power flow path between the rotatably mounted drive shaft 26 and the rotatably mounted spindle sleeve 22.

[0080] The Wolfrom gear 38 produces a reduction gear to slow speed.

[0081] As a result, the spindle sleeve 22 performs a rotary movement which is accompanied by a linear adjustment of the spindle nut 24 in or against the axial direction A.

[0082] 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 bottom wall 32 opposite to the axial direction A.

[0083] In the illustrated embodiment, the thrust bearing package 68 has three annular thrust bearing units 70, 72, 74.

[0084] 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.

[0085] The spherical axial bearing disc 76 rests in the axial direction A against an axially tapered end face 82 of the spindle sleeve 22. The axially tapered 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, thus forming a spherical contact zone 84.

[0086] 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.

[0087] The spherical contact zone 84 allows angular compensation between spindle sleeve 22 and brake caliper 12 and ensures uniform contact pressure on the rolling elements of the axial cylindrical roller bearing 78 when the brake caliper 12 bends under load.

[0088] The rolling elements of the axial cylindrical roller bearing 78 also roll on the opposite side on the planar axial bearing disk 80, which is supported on the bottom wall 32 via a planar contact zone 86.

[0089] Furthermore, the axial bearing units 70, 72, 74 are each centered on their inner circumferential surface on the outer circumferential surface of the annular portion 34 and are thus arranged coaxially to the rotation axis R of the drive shaft 26 and coaxially to the rotation axis S of the spindle sleeve 22.

[0090] When the spindle nut 24 is in the retracted position, the axial bearing package 68 is arranged in the radial direction between the annular portion 34 and the spindle nut 24, and thus at least partially arranged in the cavity 36 of the spindle nut 24.

[0091] In the illustrated embodiment, the spherical axial bearing disc 76 is arranged completely in the cavity 36 of the spindle nut 24 in the axial direction A.

[0092] Furthermore, the ring gear sleeve 46 projects beyond the open end of the spindle nut 24 into the cavity 36 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.

[0093] Here, the ring gear teeth 44 of the ring gear sleeve 46 are arranged entirely within the cavity 36 within the spindle nut 24. Furthermore, the ring gear sleeve 46 projects beyond the open first axial end 60 of the spindle sleeve 22 into the cavity 37 within the spindle sleeve 22 and is thus arranged partially within the spindle sleeve 22 in the axial direction A.

[0094] In the retracted position, the spindle sleeve 22 is also completely arranged in the cavity 36 within the spindle nut 24.

[0095] Furthermore, the gear 28 is arranged completely within the spindle nut 24 in the axial direction A when the latter is in the retracted position.

[0096] In this context, only the gears or toothed sections are considered to be gears, without taking into account the shafts or sleeves on which the gears or toothed sections are provided.

[0097] In an alternative embodiment, the gear 28 can be arranged at least partially within the spindle nut 24 in the axial direction A.

[0098] 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 88 with a motor shaft.

[0099] The motor shaft is coupled to the drive shaft 26 via a single-stage gear unit 90, wherein the single-stage gear unit 90 is arranged completely outside the spindle sleeve 22.

[0100] Alternatively, it is conceivable that the drive shaft 26 is coupled to the motor shaft of the electric motor 88 without a gear, so that the motor shaft is arranged coaxially to the drive shaft 26.

[0101] In order to adjust the spindle nut 24 in the axial direction A, the drive shaft 26 is rotated by means of the electric motor 88 and thus the spindle drive 20 is driven via the gear 28.

[0102] The structure of the spindle drive 20 or its recirculating ball system and its variants is described below.

[0103] The ball circulation system shown in Figures 1 to 3 comprises two ball circuits 92. Each ball circuit 92 has an endless closed ball chain 94 which circulates spirally in two turns 96 around the spindle sleeve 22.

[0104] In principle, the ball bearing system can have any number of ball circuits 92, each with any number of turns 96.

[0105] The balls of the ball chain 94 are guided on a radially inner ball raceway 98, which is formed spirally rising in the outer surface of the spindle sleeve 22, and by a radially outer ball raceway 100 (see Figure 1 ), which is formed spirally rising in the inner surface of the spindle nut 24.

[0106] The outer ball raceway 100 is designed as a multi-turn, uninterrupted ball raceway extending from the open to the closed end of the spindle nut 24.

[0107] The balls transmit the forces acting between the two ball raceways 98, 100.

[0108] The ball raceways 98, 100, for example, have the profile shape of a Gothic pointed arch, with the radii of the pointed arches always being slightly larger than the radius of the balls.

[0109] Each ball circuit 92 further has a ball return 102 with two deflectors 104 (see Figures 5 and 6) and a return channel 106 (see Figure 3) connecting the deflectors 104, which guide the balls.

[0110] Thus, the route of each ball circuit 92 is determined by the ball raceways 98, 100, the deflectors 104 and the return channel 106.

[0111] In the present embodiment, the two deflectors 104 of a ball return 102 are each designed as a spindle sleeve insert 108, which can be designed identically.

[0112] Each spindle sleeve insert 108 is secured, for example, in a complementarily designed pocket 110 (see Figure 3), which is provided in a spindle sleeve body 112 of the spindle sleeve 22. The spindle sleeve inserts 108 are part of the spindle sleeve 22 and, together with the spindle sleeve body 112, form the outer surface of the spindle sleeve 22.

[0113] Consequently, the ball returns 102 are integrated into the spindle sleeve 22.

[0114] The pockets 110 are milled radially into the outer surface of the spindle sleeve body 112 and interrupt the inner ball raceway 98 into a defined (integer) number of screw threads or turns 96.

[0115] The pockets 110 are aligned symmetrically and tangentially to the inner ball raceway 98.

[0116] The return channels 106 extend in the spindle sleeve body 112 below the inner ball raceway 98 in the axial direction A between the two deflectors 104 of the corresponding ball return 102.

[0117] The return channels 106 are here part of axial bores 114 (see Figure 1 ), which each extend from an end face 116 (see Figure 2) at the second axial end 62 of the spindle sleeve 22 axially, ie parallel to the rotation axis S of the spindle sleeve 22, into the spindle sleeve body 112.

[0118] In this way, the return channels 106 integrated into the spindle sleeve body 112 can be manufactured with little effort.

[0119] For example, the bore diameter is slightly larger than the ball diameter.

[0120] The deflectors 104 are designed to deflect the balls of the ball chain 94 from a winding 96 into the return channel 106 or from the return channel 106 back into a winding 96.

[0121] For this purpose, each deflector 104 has a scoop- or spoon-shaped extension 118 (see Figure 6) which, in the assembled state, projects beyond the inner ball raceway 98 and thereby represents a rolling barrier for the ball chain 94, which spoons the balls out of the inner ball raceway 98.

[0122] Formed inside the spindle sleeve insert 108 is a tube 120 having an upper opening 122 in the region of the extension 118. The expansion direction of the tube 120 forms an angle a projected orthogonally to the rotation axis S with the tangent 124 (see Figure 4) to the ball center circle 126 of the ball chain 94 and leads from the upper opening 122 via an internal 90° deflection to a lower opening 128 (see Figure 5).

[0123] The angle a is less than 90° and greater than 0°.

[0124] The tube 120 has a continuous course and, in the assembled state, connects tangentially to the return channel 106 with the lower mouth 128.

[0125] In this context, each spindle sleeve insert 108 has only a single lower opening 128, which is arranged on one side of the spindle sleeve insert 108.

[0126] Depending on the direction of rotation of the spindle sleeve 22, the individual balls of the closed ball chain 94 enter the spindle sleeve insert 108 via the upper opening 122 or via the lower opening 128.

[0127] When the individual ball in the ball chain 94 enters a spindle sleeve insert 108 of a ball return 102 via the upper opening 122, it is released from the frictional connection with the ball raceways 98, 100 and pressed by the following ball against an inner wall 130 (see Figure 6) of the deflector 104. This deflects the ball into the tube 120, pushing the leading ball forward in the ball chain 94. Consequently, the ball chain 94 pushes each individual ball through the tube 120, guiding the ball to the lower opening 128.

[0128] At the lower mouth 128, the ball leaves the spindle sleeve insert 108 and enters the return channel 106.

[0129] In the return channel 106, the ball chain 94 is guided radially below the inner ball race 98.

[0130] Once the ball chain 94 has pushed the individual ball through the return channel 106, the ball enters the tube 120 of the other spindle sleeve insert 108 of the corresponding ball return 102 via the lower opening 128 and is then guided in the tube 120 to the upper opening 122 of the other spindle sleeve insert 108. The subsequent ball in the ball chain 94 exerts a permanent pressing force on the ball.

[0131] Furthermore, the inner wall 130 ensures a defined alignment of the individual ball with the ball track 98.

[0132] As a result, the individual ball in the ball chain 94 is pressed back into frictional engagement with the ball raceways 98, 100 and leaves the other spindle sleeve insert 108.

[0133] Subsequently, the individual ball of the ball circuit 92 rolls on the ball tracks 98, 100 until it arrives again at the upper mouth 122 of the spindle sleeve insert 108.

[0134] In an alternative embodiment (see Figure 4), the ball recirculating system has only a single ball circuit 92.

[0135] In this case, the return channel 106 extends over all turns of the inner ball raceway 98, which are arranged in the axial direction A between the two deflectors 104 of the ball return 102.

[0136] In ball recirculating systems with multiple ball circuits 92, the ball circuits 92 have an axial offset and an angular offset from one another.

[0137] By dividing a single ball circuit 92 with a long ball chain 94 into two or more ball circuits 92 with correspondingly shorter ball chains 94, the accumulation of balls among themselves and the pressure between the balls is reduced. This reduces friction and increases efficiency.

[0138] A recirculating ball system according to an alternative embodiment will now be described with reference to Figures 7 to 9. The same reference numerals are used for components known from the above embodiment, and reference is made to the previous explanations.

[0139] The recirculating ball system illustrated in Figures 7 to 9 has four ball circuits 92, each with a closed ball chain 94 that circulates around the spindle sleeve 22 with a single spiral winding 96. In principle, the recirculating ball system can have any number of ball circuits 92, each with a closed ball chain 94 that circulates around the spindle sleeve 22 with a maximum of a single spiral winding 96.

[0140] In this way, the pressure between the balls is particularly low.

[0141] However, in principle and not limited to this embodiment, ball circuits 92 or groups of ball circuits 92 which have a common ball return 102 can also be provided.

[0142] In contrast to the embodiment shown in Figures 2 and 3, each spindle sleeve insert 108 has both deflectors 104 (see Figure 7) and the return channel 106 connecting the deflectors 104.

[0143] The return channel 106 is designed as a groove, while the deflectors 104 are formed by a curved channel wall 132.

[0144] The return channel 106 has an S-shaped, continuous course in both the circumferential and radial directions.

[0145] Furthermore, the return channel 106 connects tangentially to the corresponding winding 96 at the beginning and end of the inner ball raceway 98.

[0146] In the middle of its extension, the return channel 106 has its maximum recess 134 (see Figure 9).

[0147] By means of the recess 134, the balls of the ball chain 94 are guided past a threaded web 136 of the spindle nut 24.

[0148] When the balls of the ball chain 94 enter the return channel 106, they leave the ball raceways 98, 100 and are free of axial load.

[0149] The balls located in the return channel 106 are in contact with each other. A ball entering the return channel 106 pushes the balls located in the return channel 106 through it, so that at the same time, a ball leaves the return channel 106 and is pushed back into the ball raceways 98, 100. The balls of the ball chain 94 are positively guided by the return channel 106 and the deflectors 104.

[0150] In an alternative embodiment, shown in Figure 10, the ball returns 102 are formed integrally with the spindle sleeve body 112.

[0151] An actuator assembly 10 according to a further embodiment will now be described with reference to Figure 11. The same reference numerals are used for the components known from the above embodiment, and reference is made to the previous explanations.

[0152] In contrast to the embodiment shown in Figure 1, the axial bearing package 68 lies against the annular section 34 opposite to the axial direction A.

[0153] Furthermore, the gear 28 here is a two-stage gear in the form of an eccentric gear 138.

[0154] The eccentric gear 138 has a first gear pair 140, a second gear pair 142 and an eccentric shaft 144 with a bearing section 146 and an eccentric section 148.

[0155] The first gear pair 140 has an internally toothed first ring gear and an externally toothed first eccentric gear that mesh with each other, while the second gear pair 142 has an internally toothed second ring gear and an externally toothed second eccentric gear that mesh with each other.

[0156] The first ring gear is part of a ring gear sleeve 150, which is connected in a torsionally rigid manner to the bottom wall 32 of the housing 30, for example via a press fit.

[0157] The two eccentric gears or planetary gears are rotationally fixed and, in the illustrated embodiment, are integrally connected to one another to form a stepped eccentric gear 152.

[0158] The eccentric shaft 144 is mounted in the housing 30 for rotation about a rotation axis R, which forms a central longitudinal axis of the bearing section 146. Thus, the bearing section 146 is also mounted in the housing 30 for rotation about the rotation axis R.

[0159] For this purpose, the eccentric shaft 144 is rotatably mounted about the rotation axis R via a rotary bearing 154 in the first ring gear sleeve 150 and via a rolling bearing 58 in the spindle sleeve 22.

[0160] In this context, the eccentric shaft 144 forms a gear element 56 of the gear 28.

[0161] The rotation axis R of the eccentric shaft 144 is congruent or identical to the rotation axis S of the spindle sleeve 22.

[0162] Furthermore, the rotation axis R is arranged coaxially to the internal toothing of the first ring gear sleeve 150.

[0163] The eccentric section 148 has a central longitudinal axis M which is radially offset from the rotation axis R by an eccentricity e greater than zero, ie runs parallel to it at a distance e.

[0164] The stepped eccentric gear 152 is rotatably mounted on the eccentric section 148 arranged eccentrically to the rotational axis R of the eccentric shaft 144 via two further pivot bearings about the central longitudinal axis M, each of which is arranged at an axial end of the stepped eccentric gear 152.

[0165] The pivot bearings are designed, for example, as rolling bearings or plain bearings.

[0166] During operation, the spindle sleeve 22 performs rotational movements around the rotation axis R or S and represents the output element of the eccentric gear 138.

[0167] If the spindle nut 24 is now to be adjusted in the axial direction A, the drive shaft 26 is set in rotation.

[0168] This drives the eccentric shaft 144 with rotational power. Since the stepped eccentric gear 152 is rotatably mounted on the eccentric section 148, the external teeth of the first eccentric gear roll in the internal teeth of the fixed ring gear sleeve 150. The rotational movement of the stepped eccentric gear 152 is also carried out by the integrated second eccentric gear, which rolls in the internal teeth 42 of the spindle sleeve 22 and thereby drives it. The rotational power is transmitted from the spindle sleeve 22 to the spindle nut 24 via the recirculating ball system, thus axially adjusting the nut accordingly.

[0169] The stepped eccentric gear 152 forms a gear member 66, which is arranged as the only rotatably mounted gear member 66 in the power flow path between the rotatably mounted drive shaft 26 and the rotatably mounted spindle sleeve 22.

[0170] The eccentric gear 138 produces a reduction gear to slow speed.

[0171] An actuator assembly 10 according to a further embodiment will now be described with reference to Figure 12. The same reference numerals are used for the components known from the above embodiment, and reference is made to the previous explanations.

[0172] In contrast to the embodiment shown in Figure 1, the axial bearing package 68 lies opposite to the axial direction A on the annular section 34, which is designed as a separate component and is firmly connected to the bottom wall 32 of the housing 30.

[0173] Furthermore, the gear 28 here is a single-stage gear in the form of a cycloid gear 56.

[0174] The cycloidal gear 156 has an internally toothed pin ring 158 and an externally toothed cam disc 160, which are toothed together, as well as an eccentric shaft 162 with a bearing section 164 and an eccentric section 166.

[0175] In the present embodiment, the bolt ring 158 forms the annular portion 34 which is torsionally connected to the bottom wall 32 of the housing 30.

[0176] For example, the bolt ring 158 is designed in one piece.

[0177] The external toothing of cam disk 160 has a curved cycloid contour composed of identical curved sections machined into the outer circumference of cam disk 160 with a constant pitch. The profile of each curved section is designed as a shortened epicycloid, with each curved section being considered a tooth.

[0178] The internal toothing of the pin ring 158 has a rolling curve contour composed of identical curve sections machined with a constant pitch on the inner circumference of the pin ring 158. The profile of each rolling curve section is circular, with each rolling curve section being considered a tooth.

[0179] Alternatively, the internal toothing of the bolt ring 158 can have the cycloid contour and the external toothing of the cam disk 160 can have the rolling curve contour.

[0180] The external gearing and the internal gearing are designed with a tooth count difference of one, with the internal gearing having one more tooth than the external gearing.

[0181] The eccentric shaft 162 is mounted in the housing 30 for rotation about a rotation axis R, which forms a central longitudinal axis of the bearing section 164. Thus, the bearing section 164 is also mounted in the housing 30 for rotation about the rotation axis R.

[0182] For this purpose, the eccentric shaft 162 is rotatably mounted about the rotation axis R via a pivot bearing in the bottom wall 32 and via a roller bearing 58 in the spindle sleeve 22.

[0183] In this context, the eccentric shaft 162 forms a gear element 56 of the gear 28.

[0184] The rotation axis R of the eccentric shaft 162 is congruent or identical to the rotation axis S of the spindle sleeve 22.

[0185] Furthermore, the rotation axis R is arranged coaxially to the internal toothing of the bolt ring 158.

[0186] The eccentric section 166 has a central longitudinal axis M, which is radially offset from the rotational axis R by an eccentricity e greater than zero, i.e., it runs parallel to the rotational axis R at a distance e. The cam disc 160 is rotatably mounted about the central longitudinal axis M on the eccentric section 166, which is arranged eccentrically to the rotational axis R of the eccentric shaft 162, via a further pivot bearing.

[0187] For this purpose, the cam disc 160 has a central, circular-cylindrical passage, the central longitudinal axis of which is arranged coaxially to the external toothing.

[0188] The pivot bearings, for example, are designed as rolling bearings.

[0189] The cam disk 160 is coupled to the spindle sleeve 22 via several output pins 168 in a torque-transmitting manner, for example seven output pins 168.

[0190] For this purpose, the cam disc 160 has a corresponding number of bearing openings 170, which are in permanent engagement with the output pins 168, for example via rolling sleeves, and drive them in the tangential direction when the cam disc 160 rotates in the circumferential direction.

[0191] The rolling sleeves are rotatably mounted on the output journals 168 and are in rolling contact with the bearing openings 170 with their outer surface, thus reducing friction.

[0192] The diameters of the bearing openings 170 are, for example, twice the amount of the eccentricity e larger than the outer diameters of the rolling sleeves.

[0193] Furthermore, the bearing openings 170 and the output pins 168 have equal pitch circle diameters.

[0194] The output pins 168 are connected to the spindle sleeve 22 in a rotationally fixed manner, for example via receiving openings into which the output pins 168 are pressed.

[0195] In principle, the output pins 168 can be connected to the spindle sleeve 22 in any manner in a rotationally fixed manner.

[0196] The receiving openings are arranged on a pitch circle whose center coincides with the rotational axis S of the spindle sleeve 22. In the present exemplary embodiment, the receiving openings are arranged in an axial section of the spindle sleeve 22, which adjoins a first axial end 60 of the spindle sleeve 22 facing the cam disk 160.

[0197] If the spindle nut 24 is now to be adjusted in the axial direction A, the drive shaft 26 is set in rotation.

[0198] This imparts rotational power to the eccentric shaft 162. Since the cam disc 160 rotates eccentrically outside the rotational axis R and the cam disc 160 is toothed in the pin ring 158, the cycloid contour of the cam disc 160 rolls on the rolling curve contour of the stationary pin ring 158. The cam disc 160 is coupled to the spindle sleeve 22 via the output pins 168 and imparts rotational power to the spindle sleeve, thereby axially adjusting the spindle nut 24 accordingly. The eccentric shaft 162 and the spindle sleeve 22 rotate in opposite directions.

[0199] The cam disc 160 forms a gear member 66, which is arranged as the only rotatably mounted gear member 66 in the power flow path between the rotatably mounted drive shaft 26 and the rotatably mounted spindle sleeve 22.

[0200] The cycloidal gear 156 produces a reduction gear to slow speed.

[0201] In all embodiments, an actuator assembly 10 for an electromechanical vehicle brake is provided in this way, which is designed to be particularly compact, in particular in the axial direction A.

Claims

Patent claims 1. Actuator assembly (10) 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) 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) is movable 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), wherein the gear (28) is arranged at least partially within the spindle sleeve (22) in the axial direction (A), and wherein the spindle sleeve (22) at least one ball return (102) of the spindle drive (20) is integrated.

2. Actuator assembly (10) according to claim 1, characterized in that the spindle sleeve (22) has at least two turns (96), each associated with its own ball circuit (92).

3. Actuator assembly (10) according to claim 2, characterized in that the ball return (102) integrated into the spindle sleeve (22) forms a common return for at least two ball circuits (92).

4. Actuator assembly (10) according to claim 2, characterized in that at least one further ball return (102) of the spindle drive (20) is integrated into the spindle sleeve (22), wherein each of the ball returns (102) integrated into the spindle sleeve (22) forms a return for at least one of the windings (96), in particular wherein each ball return (102) is part of a ball circuit (92) assigned only to it.

5. Actuator assembly (10) according to one of the preceding claims, characterized in that each ball return (102) has a return channel (106) and two deflectors (104).

6. Actuator assembly (10) according to claim 5, characterized in that the spindle sleeve (22) has a spindle sleeve insert (108) for each ball return (102) which is fastened to a spindle sleeve body (112) of the spindle sleeve (22), wherein the spindle sleeve insert (108) has the return channel (106) and the two deflectors (104) of the corresponding ball return (102).

7. Actuator assembly (10) according to claim 5, characterized in that the spindle sleeve (22) has a spindle sleeve insert (108) for each deflector (104) which is fastened to a spindle sleeve body (112) of the spindle sleeve (22), wherein the spindle sleeve insert (108) has the corresponding deflector (104).

8. Actuator assembly (10) according to claim 7, characterized in that each return channel (106) is formed in the spindle sleeve body (112).

9. Actuator assembly (10) according to one of the preceding claims, characterized in that the spindle sleeve (22) has a cavity (37) and an internal toothing (42) of the gear (28) delimiting the cavity (37), and in that the internal toothing (42) is designed in one piece with the spindle sleeve (22) or is part of a ring gear which is connected to the spindle sleeve (22) in a rotationally fixed manner.

10. Actuator assembly (10) according to claim 9, characterized in that the internal toothing (42) extends only over a part of the total axial length of the cavity (37).

11. Actuator assembly (10) according to one of the preceding claims, characterized in that a gear element (56) of the gear (26) is mounted in the spindle sleeve (22) via a rolling bearing (45).

12. Actuator assembly (10) according to claim 11, characterized in that the gear element (56) is an input pinion shaft or a planet carrier (54).

13. Actuator assembly (10) according to one of the preceding claims, characterized in that in the force flow path between the rotatably mounted Drive shaft (26) and the rotatably mounted spindle sleeve (22) only a single rotatably mounted gear member (66), in particular a gear member (66) of the gear (28) rotatably mounted about its own axis of rotation, is arranged.

14. Actuator assembly (10) according to one of the preceding claims, characterized in that the gear (28) is a reduction gear in the form of a Wolfrom gear (38), an eccentric gear (138) or a cycloidal gear (156).

15. Actuator assembly (10) according to one of the preceding claims, characterized in that the gear (28) is arranged at least partially within the spindle nut (24) in the axial direction (A).

16. Actuator assembly (10) according to one of the preceding claims, characterized in that the spindle sleeve (22) bears against a spherical axial bearing disc (76) via an axially tapered end face (82).

17. Actuator assembly (10) according to claim 16, characterized in that the axially tapered end face (82) of the spindle sleeve (22) is convex.

18. Actuator assembly (10) according to claim 16 or 17, characterized in that the spherical axial bearing disc (76) is arranged at least partially within the spindle nut (24) in the axial direction (A).

19. Actuator assembly (10) according to one of the preceding claims, characterized in that both axial ends (60, 62) of the spindle sleeve (22) have a central opening (64).

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