VEHICLE BRAKE ACTUATOR AND ELECTROMECHANICAL BRAKE
20230150471 ยท 2023-05-18
Inventors
Cpc classification
F16D2200/0004
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D65/18
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D2250/0076
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B60T13/746
PERFORMING OPERATIONS; TRANSPORTING
F16D55/28
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D2250/0061
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D65/0971
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D55/226
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D2125/40
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
Abstract
The disclosure relates to a vehicle brake actuator and an electromechanical brake. The vehicle brake actuator comprises a brake housing, a spindle drive which is arranged in the brake housing and which has a spindle and a spindle nut mounted on the spindle, and a brake piston and a pot sleeve. The brake piston is movable between a retracted and a deployed position in order to apply a brake pad to a brake rotor. The brake piston is at least partially guided in axially displaceable fashion in an interior space of the pot sleeve. The pot sleeve has a base and is pushed in its longitudinal direction into the brake housing and is mounted radially therein.
Claims
1. A vehicle brake actuator for an electromechanical brake, comprising: a brake housing, having a spindle drive which is arranged in the brake housing and which has a spindle and a spindle nut mounted on the spindle, and a brake piston, which is movable between a retracted and a deployed position in order to apply a brake pad to a brake rotor, and having a pot sleeve, in an interior space of which the brake piston is at least partially guided in axially displaceable fashion, wherein the pot sleeve has a base and the pot sleeve is pushed in its longitudinal direction into the brake housing and is mounted radially therein.
2. The vehicle brake actuator according to claim 1, wherein the pot sleeve and the brake piston are accommodated in the brake housing, wherein the pot sleeve has an axial stop with which said pot sleeve is supported on the brake housing when the brake is actuated.
3. The vehicle brake actuator according to claim 2, wherein the stop is a radial shoulder formed integrally on the pot sleeve or is a fastening means element attached the pot sleeve.
4. The vehicle brake actuator according to claim 1, wherein the spindle is supported axially on the base of the pot sleeve when the brake is actuated.
5. The vehicle brake actuator according to claim 4, wherein a spindle bearing with a bearing contact surface is arranged between the base of the pot sleeve and the spindle, which spindle bearing is configured to accommodate radial reaction forces when the brake is actuated.
6. The vehicle brake actuator according to claim 5, wherein the spindle bearing is an axial bearing, via which the axial reaction forces of the spindle are accommodated.
7. The vehicle brake actuator according to claim 6, wherein a bearing disc is arranged axially between the base of the pot sleeve the rolling elements of the spindle bearing, which bearing disc is pressed against the pot sleeve so as to be secured against rotation by frictional engagement and/or positive engagement.
8. The vehicle brake actuator according to claim 1, wherein the brake piston is formed as a spindle nut by virtue of a spindle thread being formed on its inner side.
9. The vehicle brake actuator according to claim 1, wherein a rotational locking arrangement is provided between the pot sleeve and the brake piston that is accommodated in linearly displaceable fashion in said pot sleeve, which rotational locking arrangement allows a linear displacement of the brake piston but prevents a rotation of the brake piston relative to the pot sleeve.
10. The vehicle brake actuator according to claim 1, wherein, at the brake pad side, a seal is provided between the brake piston and the pot sleeve.
11. The vehicle brake actuator according to claim 5, wherein a core diameter of a thread of the spindle nut is greater than an outer diameter of the spindle bearing for the purposes of axial displaceability of the brake piston over the spindle bearing.
12. The vehicle brake actuator according to claim 5, wherein the spindle has, at a brake pad side, a shank portion of thickened cross section, which on an outer shell has a screw mechanism of the spindle drive, and has a drive shaft projection of smaller cross section in relation to said shank portion, and has a transition portion between the shank portion and the drive shaft projection, wherein the bearing contact surface of the spindle bearing bears against a complementary contact surface on the transition portion.
13. The vehicle brake actuator according to claim 12, wherein the bearing contact surface of the spindle bearing and the contact surface of the transition portion are of spherical shape.
14. The vehicle brake actuator according to claim 13, wherein the spherical bearing contact surface has a first curvature radius, wherein the contact surface has a second curvature radius, and wherein the first curvature radius and the second curvature radius are different.
15. The vehicle brake actuator according to claim 14, wherein at least a first centre of the first or of the second curvature radius has a radial offset relative to an axis of rotation of the spindle.
16. An electromechanical brake having an electric motor for actuating the brake, which electric motor is coupled in torque-transmitting fashion to the brake piston, and having a vehicle brake actuator according to claim 1.
17. The vehicle brake actuator according to claim 3, wherein the spindle is supported axially on the base of the pot sleeve when the brake is actuated.
18. The vehicle brake actuator according to claim 17, wherein a rotational locking arrangement is provided between the pot sleeve and the brake piston that is accommodated in linearly displaceable fashion in said pot sleeve, which rotational locking arrangement allows a linear displacement of the brake piston but prevents a rotation of the brake piston relative to the pot sleeve.
19. The vehicle brake actuator according to claim 18, wherein, at the brake pad side, a seal is provided between the brake piston and the pot sleeve.
20. The vehicle brake actuator according to claim 1, wherein the brake piston is formed as a spindle nut by virtue of a spindle thread being formed on its inner side.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0061] The disclosure and further advantageous exemplary arrangements and refinements thereof will be described and discussed in more detail below on the basis of the examples illustrated in the drawings. In the drawings:
[0062]
[0063]
[0064]
[0065]
[0066]
[0067]
[0068]
[0069]
[0070]
[0071]
DETAILED DESCRIPTION
[0072] The following detailed description in conjunction with the appended drawings, in which identical elements are denoted by the same reference designations, is intended as a description of different exemplary arrangements of the disclosed subject matter, and is not intended to represent the only arrangements. Each exemplary arrangement described in this disclosure serves merely as an example or for illustration, and is not to be interpreted as being preferred or advantageous in relation to other exemplary arrangements.
[0073] All features disclosed below with regard to the exemplary arrangements and/or the appended figures may, individually or in any desired sub-combination, be combined with features of the aspects of the present disclosure, including features of preferred exemplary arrangements, assuming that the resulting combination of features is meaningful to a person skilled in the art in the technical field.
[0074]
[0075] The brake 10 comprises a brake housing 14 with a brake caliper 16 as part of the brake housing 14. The brake housing 14 may at least partially also be assigned to the vehicle brake actuator 12. The brake caliper 16 surrounds a brake disc 18, for example a brake disc rotor, which is enclosed in an axial direction by two brake pads 20, 22. The inner brake pad 20 along the axis of rotation 24 of the vehicle brake actuator 12 is actively subjected to a brake-application force Fz by the vehicle brake actuator 12. In the present case (in the ideal situation of compensated transverse forces), the axis of rotation 24 of the vehicle brake actuator 12 also corresponds to the cylinder axis of the brake housing 14 and the brake disc axis of rotation of the brake disc 18.
[0076] The axially displaceable brake caliper 16 ensures that the outer brake pad 22 in the axial direction is likewise subjected to the brake-application force Fz. Here, the brake-application force Fz is distributed substantially uniformly, in terms of magnitude, between the inner brake pad 20 and the outer brake pad 22. Thus, for both brake pads 20, 22, owing to the pressing force that is provided, frictional engagement with the brake disc 18 can be ensured, which frictional engagement is utilized for the deceleration or immobilization of a vehicle.
[0077] The brake 10 furthermore has an electromechanical actuating unit 26 that is utilized, together with the vehicle brake actuator 12, to generate the brake-application force Fz. Relative to the vehicle brake actuator 12, the electromechanical actuating unit 26 is arranged on the opposite side in relation to the brake disc 18 along the axis of rotation 24. The electromechanical actuating unit 26 comprises at least one electric motor 28 and one reduction gearing 30.
[0078] The components of the electromechanical actuating unit 26 are accommodated by the brake housing 14, which may be configured as a skeleton-like frame composed of metal or of fibre-reinforced plastic. The electromechanical actuating unit 26 forms a closed, separately installable subassembly 32.
[0079] The vehicle brake actuator 12 comprises a spindle 34 with a drive shaft projection 36, with a second shank portion 38 at a brake pad side, and with a transition portion 40 that is arranged between the drive shaft projection 36 and the shank portion 38 along the axis of rotation 24 of the spindle 34. The diameter of the drive shaft projection 36 of the vehicle brake actuator 12 along the radial direction is smaller than the diameter of the shank portion 38 along this direction. Correspondingly, the spindle 34 narrows in terms of its diameter in the region of the transition portion 40.
[0080] The vehicle brake actuator 12 furthermore has a brake piston 42 that is configured as a spindle nut. The spindle drive 44 of the vehicle brake actuator 12 is in the present case configured as a recirculating ball screw that has no self-locking action. Here, the spindle drive 44 comprises a mechanism screw 46 in which balls 48 are arranged and roll. The spindle 34 and the brake piston 42 have mutually corresponding raceway parts. The balls 48 can, along the ball raceways 50 of the mechanism screw 46, allow a translational movement of the brake piston 42 relative to the spindle 34 along the axis of rotation 24. For this purpose, the ball raceways 50 are formed at least partially in the shank portion 38 of the spindle 34 and in the brake piston 42.
[0081] The diameter of the ball raceways 50 corresponds, taking into consideration manufacturing tolerances and required gap dimensions, to the diameter of the balls 48.
[0082] The translational movement of the brake piston 42 in the direction of the brake disc 18 causes the brake piston 42 to be moved in the direction of the inner brake pad 20 and thus ensures that the brake-application force Fz is actively applied to the inner brake pad 20.
[0083] The vehicle brake actuator 12 furthermore comprises a pot sleeve 54 that has a side wall 56 and a base 58. The open end of the pot sleeve 54 is arranged at a brake pad side along the axis of rotation 24. This means that the base 58 is provided at the opposite end of the pot sleeve 54 in relation to the brake disc 18. The base 58 has a passage hole 60 for the drive shaft projection 36 of the spindle 34, which is held in said passage hole by a radial bearing 62.
[0084] The side wall 56 and the base 58 define an interior space 64 of the pot sleeve 54, in which at least the spindle 34 and the brake piston 42 are at least partially arranged. Owing to the linear displaceability of the brake piston 42, this can also be arranged at least partially outside the interior space 64.
[0085] The pot sleeve 54 makes it possible for the vehicle brake actuator 12 to be configured as a separate subassembly 66. The brake housing 14 has, for the subassembly 66, a corresponding receiving space 68 in which the subassembly 66 can be positioned and thus mounted radially and axially therein.
[0086] Within the vehicle brake actuator 12, the brake piston 42 is guided linearly, and secured against rotation, relative to the brake housing 14 and the pot sleeve 54 by a rotational locking arrangement 70. For this purpose, the brake piston 42 may have an axial groove that engages with a rotational securing element.
[0087] Here, the rotation of the spindle 34 is ensured by the electric motor 28, which engages with the drive shaft projection 36 of the spindle 34 via the reduction gearing 30. The rotation of the spindle 34 in conjunction with the rotational blocking of the brake piston 42 ensures a translational movement of the brake piston 42. This movement is transmitted to the brake pads 20, 22. The brake-application force Fz that is generated is proportional to the torque that is imparted to the drive shaft projection 36 by the electric motor 28 and the reduction gearing 30.
[0088] Owing to the brake-application force Fz that is generated, a reaction force Fr that is opposed to the brake-application force Fz arises along the axis of rotation 24. Owing to the elastic expansion of the components of the brake 10, an angular offset may generally arise between the brake disc axis of rotation and the cylinder axis of the brake housing 14, such that the reaction force Fr has eccentric force components, These eccentric force components can lead to an instability of the components of the vehicle brake actuator 12 along the radial direction, if the core diameter DK of the thread of the brake piston 42 is smaller than the outer diameter DL of a bearing that is intended to accommodate the reaction force Fr.
[0089] Thus, the elimination of an otherwise conventional separate spindle nut, by virtue of the fact that the brake piston 42 assumes the function of said spindle nut, has the effect that the brake piston 42 can be enlarged in a radial direction. In this way, despite an unchanged radial structural space of the brake 10, it is made possible to enlarge the core diameter DK.
[0090] In one exemplary arrangement, the core diameter DK can be radially enlarged so as to be greater than the outer diameter DL of a spindle bearing 72 of the vehicle brake actuator 12 in a radial direction, which spindle bearing accommodates the reaction force Fr. It is thus made possible for the force engagement point of the eccentric force components of the reaction force Fr to be shifted radially outwards to such an extent that the effect of the eccentric force components is diminished, and the compensation by the spindle bearing 72 is ensured even without special bearing geometries of the spindle bearing 72. Thus, the orientation and mounting of the individual components of the vehicle brake actuator 12, and the application of force to the brake pads 20, 22, are improved.
[0091] In the present case, the spindle bearing 72 is of rotationally symmetrical design, and is configured as an axial bearing.
[0092] In the present case, the spindle bearing 72 has, on a bearing ring 73, a bearing contact surface 74 which faces towards the transition portion 40 and which is in contact with a complementary contact surface 76 provided by the transition portion 40 of the spindle 34. The bearing contact surface 74 and the contact surface 76 may be planar. For example, the bearing contact surface 74 and the contact surface 76 may extend perpendicular to the axis of rotation 24 (not shown here).
[0093] In order to further improve the compensation of the eccentric force components of the reaction force Fr, the bearing contact surface 74 of the spindle bearing 72 and the contact surface 76 of the transition portion 40 are of spherical shape in the present exemplary arrangement.
[0094] In this exemplary arrangement, one of the two contact surfaces of this contact, that is to say either the spherical bearing contact surface 74 of the spindle bearing 72 or the complementary contact surface 76 of the transition portion 40, is of concave shape, whereas the other is of convex shape.
[0095] In one exemplary arrangement, the contact surfaces 74, 76 have different curvature radii, whereby, in the situation without application of force, linear contact in the form of a circular line between the bearing ring of the spindle bearing 72 and the transition portion 40 of the spindle 34 is ensured. The centre of the circular line is congruent with the axis of rotation 24 of the spindle 34. With increasing reaction force Fr, elastic flattening of the contact surfaces 74, 76 has the effect that the linear contact widens to become areal contact.
[0096] In order for the diameter of the circular line at the midpoint of the contact angle to be made as large as possible, the centre of the curvature radius of the spherical bearing contact surface 74 and/or the centre of the curvature radius of the complementary contact surface 76 may each have an offset, along the radial direction, with respect to the respective axis of rotation of the spindle bearing 72 or of the spindle 34. Such an offset has the effect that the diameter of the circular line is enlarged, and the contact between the contact surfaces 74, 76 is shifted outwards in a radial direction. It is thus made possible for restoring forces of greater magnitude in the direction of the axis of rotation 24 of the spindle 34 to be generated. For example, the enlargement of the contact angle and of the diameter of the circular line has the effect that the contact pressure in the contact zone between the contact surfaces 74, 76 is reduced. The centring action of the spherical bearing contact surface 74 of the bearing ring 73 of the spindle bearing 72 is thus improved.
[0097] The spindle bearing 72 furthermore has a planar contact surface 78, which is arranged oppositely in relation to the bearing contact surface 74 along the axis of rotation 24.
[0098]
[0099] Thus, the reaction force Fr that arises is, from the shank portion 38 of the spindle 34, accommodated by the base 58 of the pot sleeve 54 via the spindle bearing 72.
[0100] In the region of the brake-pad-side end of the pot sleeve 54, this has, in the present exemplary arrangement, a radially integrally formed shoulder 83 which is formed integrally with the side wall 56 and which provides a stop 84 and by means of which the pot sleeve 54 is supported on the brake housing 14. Thus, the reaction force Fr that is accommodated by the base 58 of the pot sleeve 54 is transmitted via the side wall 56 and the stop 84 to the brake housing 14.
[0101] In order to protect the spindle drive 44, the pot sleeve 54 has a radially internally situated groove in which a seal 86 is arranged and which acts between the pot sleeve 54 and the brake piston 42.
[0102] The pot sleeve 54 and the brake piston 42 each additionally have a radially externally situated groove in which an additional seal 88 in the form of an encircling corrugated bellows is arranged. In this way, the subassembly 66 of the vehicle brake actuator 12 is sealed off with respect to other parts of the brake 10. The seal 88 is configured to ensure the sealing action over the entire movement travel (stroke) of the brake piston 42.
[0103] In the present case, at the brake pad side, the brake piston 42 comprises an end wall 90 with an end surface of circular-ring-shaped form, which is provided for the application of force to the inner friction pad 20. The circular ring shape ensures an optimized force distribution of the brake-application force Fz over the receiving surface 92 of the inner friction pad 20.
[0104] The spindle drive 44 comprises ball return guides 94 that are integrated within the spindle 34.
[0105] In a pre-assembly step, both the mechanism screws 46 of the spindle 34 and the ball return guides 94 integrated in the spindle 34 can be fully filled with balls 48. The brake piston 42 can subsequently be pushed onto the spindle 34.
[0106] By the ball return guides 94, which are integrated in the spindle 34, of the spindle drive 44, it is also ensured that, whilst providing the same stroke, the spindle drive 44 can be configured to be axially shorter than in the case of known and spindle drives without integrated ball return guides. The reason for this is the possibility for the spindle bearing 72, on which the spindle drive 44 is supported at the open end of the brake piston 42, to be able to project a certain distance into the brake piston 42 when the latter is in the retracted state, without the overlap of the balls 48 being eliminated.
[0107] In the present case, the pot sleeve 54 furthermore has an elevated plateau 96 which extends axially in the direction of the brake-pad-side end of the pot sleeve 54 proceeding from the base 58 of the pot sleeve 54. By the elevated plateau 96, it is made possible for the spindle bearing 72 and the bearing disc 82 to be positioned axially closer to the brake-pad-side end of the pot sleeve 54. The axial length of the brake caliper 16 of the brake 10 can thus be shortened. In this way, the structural space required in an axial direction can be reduced.
[0108]
[0109] In this exemplary arrangement, the pot sleeve 54 of the vehicle brake actuator 12 comprises, instead of a radially integrally formed shoulder 83, a radially externally situated groove 98 in which a fastening 100 is arranged, which provides the stop 84 with respect to the brake housing 14. In the present case, the fastening 100 is a circlip.
[0110] This exemplary arrangement provides the additional advantage that the pot sleeve 54 can generally be pushed axially into the brake housing 14 from both sides. In this way, the installation of the pot sleeve 54 is simplified.
[0111] Furthermore, the pot sleeve 54 in this exemplary arrangement does not have an elevated plateau 96. The base 58 of the pot sleeve 54 substantially has an axial extent that remains uniform with increasing radial distance to the axis of rotation 24 of the spindle 34. As a result, the pot sleeve 54 has a simpler geometry, whereby the outlay on production is reduced.
[0112]
[0113] By a positively engaging connection 102 that is displaceable along the axis of rotation 24, the pot sleeve 54 is coupled to the electromechanical actuating unit 26 such that the reduction gearing 30 is centred relative to the pot sleeve 54. In this exemplary arrangement, the displaceable positively engaging connection 102 comprises a shaft-hub connection 104 with a spline toothing 106 for transmitting torque.
[0114]
[0115] As an alternative to the shaft-hub connection 104, the pot sleeve 54 in this embodiment has a tongue-and-groove connection 108. The tongue, in this case in the form of a bolt, is in this case pressed into an associated bore that is formed into the base-side end surface of the pot sleeve 54.
[0116]
[0117] The figure shows the passage hole 60 in the base 58 of the pot sleeve 54, which passage hole is provided for the drive shaft projection 36. Proceeding from the base 58, the elevated plateau 96 extends in the direction of the brake-pad-side end of the pot sleeve 54. Furthermore, the pot sleeve 54 according to this exemplary arrangement has a radially integrally formed shoulder 83.
[0118] The rotational locking arrangement 70, which acts between the pot sleeve 54 and the brake piston 42, comprises an elongated hole 110 into which a rotational securing element engages.
[0119]
[0120] The figure shows that a sliding block 112 is provided, which is positioned in the elongated hole 110 of the rotational locking arrangement 70 and allows linear displaceability of the brake piston 42 with respect to the pot sleeve 54, but which prevents a rotation of the brake piston 42 relative to the pot sleeve 54.
[0121] The end stops 114, 116 of the elongated hole 110 for the sliding block 112 define the stroke of the maximum possible movement travel of the brake piston 42 (without brake pads).
[0122]
[0123] The brake housing 14 and the pot sleeve 54 are shown. The pot sleeve 54 is rotationally secured relative to the brake housing 14. The rotational securing means 118 involves positive engagement, which is implemented in the present case by way of a tangential pin connection 120. By virtue of the fact that the pot sleeve 54 is rotationally secured relative to the brake housing 14, the brake piston 42 is rotationally secured relative to the brake housing 14 indirectly via the rotational locking arrangement 70. It is thus ensured that the brake piston 42 does not rotate relative to the brake pad 20, whereby an optimized application of force to the brake pad 20 is ensured.
[0124]
[0125] The pot sleeve 54 has, in turn, a groove 98 in which a fastening arrangement 100 can be arranged in order to provide the stop 84 for the coupling to the brake housing 14.
[0126] It can also be seen that the spline toothing 106 is variable with regard to the number of splines.
[0127]
[0128] It can be seen that the brake housing 14 has a receiving space 68 which corresponds to the pot sleeve 54 and which is provided by way of an at least partially circular cylindrical inner contour 122. The pot sleeve 54 can this be pushed in an axial direction, with an oversize, into the receiving space 68 of the brake housing 14. The pot sleeve 54 is subsequently radially mounted in the receiving space 68.
[0129] If the pot sleeve 54 does not have a radially integrally formed shoulder 83 but instead has a radially externally situated groove 98 for a fastening arrangement 100, then the pot sleeve 54 can be pushed into the receiving space 68 in axially opposite directions. The installation of the pot sleeve 54, and of the subassembly 66 of the vehicle brake actuator 12 as a whole, is thus simplified.
[0130] Alternatively, the pot sleeve 54 may also be radially pressed into the receiving space 68. By way of a pressing-in operation, rotational securing 118 of the pot sleeve 54 relative to the brake housing 14 can be ensured even without a tangential pin connection 120.
[0131] In this exemplary arrangement, the rotational securing 118 of the pot sleeve 54 relative to the brake housing 14 is however ensured by positive engagement by a tongue-and-groove connection 124. This is illustrated in