Patent Publication Number: US-2023151863-A1

Title: Actuator assembly for a vehicle brake and electromechanical vehicle brake

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Priority Application No. 102021129969.1, filed Nov. 17, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The disclosure concerns an actuator assembly for an electromechanical vehicle brake with a carrier assembly having a frame part, and a guide part which is received in the frame part and in which an actuating slide for a brake pad is mounted so as to be linearly displaceable. The disclosure also concerns an electromechanical brake. 
     BACKGROUND 
     An actuating slide of a brake may be moved optionally between a retracted position and an extended position, and serves to apply a brake pad to a brake disc. 
     Usually, for linear guidance of the actuating slide, a guide part is provided in which the actuating slide is received and linearly guided. 
     In order to guarantee a reliable force transmission to the actuating slide, ‘the connection between the frame part and the guide part must be made as stiff as possible. 
     SUMMARY 
     What is needed is a connection between a frame part and a guide part of an actuator assembly which is sufficiently stiff for a reliable force transmission and also easy to produce. 
     An actuator assembly for a vehicle brake is disclosed herein, with a carrier assembly having a frame part, and a guide part in which an actuating slide for a brake pad is mounted so as to be linearly displaceable, wherein the guide part has a rotational locking geometry by which the guide part is rotationally fixedly received in the frame part by form fit. 
     The actuator assembly according to the disclosure has the advantage that the connection between the frame part and the guide part is particularly stiff. This guarantees a stable guidance of the actuating slide and a reliable force transmission to the actuating slide. For example, it avoids a relative movement between the frame part and the guide part, such as a rotational or tilting movement. 
     The form-fit, rotationally fixed connection is preferably a shaft-hub connection, for example a splined shaft connection. A shaft-hub connection is easy to produce and allows a form-fit connection in a simple and reliable fashion. A splined shaft connection also achieves the advantage that the guide part and the frame part can easily be joined together by an axial push-fit movement. 
     Instead of a splined shaft connection, a polygonal connection or a notched toothing are conceivable, and other connections which transmit torque. 
     According to one exemplary arrangement, the actuator assembly comprises a brake caliper, and the guide part is a bearing sleeve which is received in the brake caliper. 
     This means that the guide part can be produced separately from the brake caliper, so a different material can be selected for the guide part than for the brake caliper, for example a material with particularly good slide properties. Thus a machining of the running face may be omitted. 
     According to an alternative exemplary arrangement, the actuator assembly comprises a brake caliper, and the guide part is a sleeve-like portion of the brake caliper. This means that the sleeve-like portion is formed integrally with the brake caliper. In comparison with a two-piece design with separate bearing sleeve, this achieves the advantage that fewer components are required and assembly is thereby simplified. 
     A space for a brake disc is for example present in the brake caliper, wherein the guide part is open towards the space so that the actuating slide can be moved into the space. Thus the brake pad arranged in the space can be moved by the actuating slide. 
     In one exemplary arrangement, the actuating slide can be moved between a retracted position and an extended position. 
     A fixing interface for an electric motor may be formed on the frame part. 
     Thus there is no need for a separate bracket for the electric motor, and the actuator assembly can be designed compactly. 
     Furthermore, a receiving space for a gear unit may be formed on the frame part. This further contributes to a compact design of the actuator assembly. 
     The frame part may accordingly receive the electric motor and gear mechanism and absorb their forces. 
     The actuator assembly comprises a gear unit driving a spindle drive on which the actuating slide is mounted, such that a rotation of the spindle drive causes an axial displacement of the actuating slide. Such an arrangement allows for a rotational motion to be translated into a linear motion in a simple fashion. 
     For example, the electric motor is coupled for drive purposes to the actuating slide via the gear unit and spindle drive in order to move the actuating slide between the retracted position and the extended position. The actuator assembly is accordingly an electromechanical actuator assembly. An electric motor allows for a sufficiently high force to be generated to apply a brake pad to a brake disc by the actuating slide. 
     In one exemplary arrangement, the actuating slide is guided rotationally fixedly in the guide part by a rotational locking element. This contributes to a particularly stable guidance of the actuating slide. Because a rotation of the actuating slide is prevented, it is guaranteed that a rotational movement of the spindle drive is completely translated into a linear movement of the actuating slide. 
     The disclosure furthermore concerns an electromechanical brake with an actuator assembly according to the disclosure and a brake disc which can be decelerated thereby. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Further advantages and features of the disclosure will become apparent from the following description and from the accompanying drawings, to which reference is made. In the drawings: 
         FIG.  1    shows, in a sectional illustration, an electromechanical brake according to the disclosure with an actuator assembly according to the invention in a first exemplary arrangement, 
         FIG.  2    shows a drive assembly of the actuator assembly according to the disclosure from  FIG.  1   , 
         FIG.  3    shows, in an exploded perspective view, a carrier assembly of the drive assembly from  FIG.  2   , and 
         FIG.  4    shows, in a sectional illustration, an actuator assembly according to the disclosure in a further exemplary arrangement. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows an actuator assembly  10  as part of an electromechanical vehicle brake. 
     The actuator assembly  10  comprises a control assembly  12 , mountable as a separate sub-unit, and a drive assembly  14 , also mountable as a separate sub-unit (see  FIG.  2   ). 
     The control assembly  12  and the drive assembly  14  are arranged in a common housing  16 . 
     The housing  16  comprises a substantially sleeve-like housing base part  18  and a housing cover  20 , by which the housing base part  18  can be tightly closed in fitted state. 
     In the exemplary arrangement shown, the housing cover  20  is substantially dish-shaped. 
     Both the housing base part  18  and the housing cover  20  are made of a plastic material. Thus the housing  16  as a whole is made of plastic material. 
     Furthermore, the actuator assembly  10  comprises a brake caliper  15  in which a space  17  for a brake disc  19  is formed. The end of the housing  16  closest to the brake disc  19  is pushed partially onto the brake caliper  15 . 
     The drive assembly  14  comprises a carrier assembly  22  which has a plate-like frame part  24 , as  FIGS.  2  and  3    show clearly. 
     A first fixing interface  26  is provided on the plate-like frame part  24 , at which, in the exemplary arrangement illustrated, an electric motor  28  is attached. 
     More precisely, the electric motor  28  is captively connected to the frame part  24  via the first fixing interface  26 . For this, a bore  30  (see  FIG.  3   ) is provided on the frame part  24 , via which the electric motor  28  may be attached to the frame part  24  by a fastener, such as a screw. The frame part  24  absorbs the forces of the electric motor  28  and retains this. 
     In addition, a centring device  32  (see  FIG.  3    again) in the form of a centring face is arranged on the frame part  24 . The electric motor  28  may thus be attached to the frame part  24  so as to be centred with respect to a centre axis  34  of the first fixing interface  26 . 
     Also, a rotational locking device  36  is provided in the form of a rotational locking depression, which is configured to prevent the electric motor  28  from rotating relative to the frame part  24 . 
     An output gear wheel  40  is arranged on an output shaft  38  of the electric motor  28  for the introduction of torque into the drive assembly  14 , as shown in  FIG.  2   . 
     In addition, a bearing journal  42  is provided on the frame part  24 , on which, in the exemplary arrangement illustrated, a gear wheel  44  is mounted which meshes with the output gear wheel  40 . 
     Also on the frame part  24 , a receiving space  46  is provided for a planetary gear stage  48 . 
     A centre axis  50  of the receiving space  46  is arranged substantially parallel to the centre axis  34  of the first fixing interface  26 . 
     Furthermore, a reinforcement part  52  is attached to the frame part  24  such that it spans the receiving space  46  axially at the end relative to the centre axis  50 . 
     In the exemplary arrangement shown, the reinforcing part  52  is substantially cruciform. 
     Also, a bearing point  54  is provided on the reinforcing part  52  for a gear wheel  56 , which is arranged coaxially to the planetary gear stage  48 . 
     The gear wheel  56  meshes with the gear wheel  44 . 
     Accordingly, the gear wheel  44  and the gear wheel  56  form a wheel gear mechanism  58 , for which the output gear wheel  40  acts as the input member. 
     Furthermore, the gear wheel  56  is formed integrally with a sun gear  60  (see  FIG.  1   ) of the planetary gear stage  48 . In this way, the wheel gear mechanism  58  and the planetary gear stage  48  are coupled together for drive purposes. 
     The planetary gear stage  48  also comprises a ring gear  62  which runs substantially around an inner circumference of the receiving space  46  (see  FIG.  3   ). 
     For drive purposes, in the exemplary arrangement illustrated, a total of three planet gears  64  are provided between the sun gear  60  and the ring gear  62 , as  FIG.  2    shows clearly. These planet gears are mounted rotatably on a planet carrier  66 . 
     The planet carrier  66  forms an output element of the planetary gear stage  48 . 
     The wheel gear mechanism  58  and the planetary gear stage  48  are jointly known as the gear unit  67 . 
     The frame part  24  additionally comprises a second fixing interface  68 , which is configured for fixing of a guide part  70  for a spindle drive  72 . 
     In the exemplary arrangement shown in  FIGS.  1  to  3   , the guide part  70  is a bearing sleeve which is received in the brake caliper  15 . For example, the bearing sleeve is pressed into the brake caliper or welded thereto. 
     A centre axis of the second fixing interface  68  is here congruent with the centre axis  50  of the receiving space  46  and for this reason carries the same reference sign. 
     The second fixing interface  68  has a rotational locking geometry  74  which runs circumferentially around the centre axis  50  and is formed by several radial protrusions  76  and radial depressions  78  arranged alternately around the circumference. The rotational locking geometry  74  is thus a shaft-hub connection, in this exemplary arrangement a splined shaft geometry. For reasons of greater clarity, in  FIG.  3    only one exemplary radial protrusion  76  and one exemplary radial depression  78  carry a reference sign. 
     The radial protrusions  76  and the radial depressions  78  have a constant pitch. This means that the radial depressions  78  are each the same length in the circumferential direction. The radial protrusions  76  are also each the same length in the circumferential direction. In addition, a radial height of the radial protrusions  76  is constant. 
     In this way, a rotational locking device  80  of the second fixing interface  68  is formed. 
     A complementary rotational locking geometry  82  is provided on the end of the guide part  70  to be coupled to the second fixing interface  68 , so that the guide part  70  can be inserted along the centre axis  50  into the rotational locking geometry  74  of the second fixing interface  68  and be held there rotationally fixedly by form fit. The rotational locking geometry is also a splined shaft geometry. 
     A spindle drive  72  is received in the interior of the guide part  70 . 
     This comprises a spindle  84 , in the present case configured as a recirculating ball spindle (see in particular  FIGS.  1  and  2   ). 
     The spindle  84  is rotationally fixedly connected to the planet carrier  66  via a toothing portion  86 . 
     Thus the spindle drive  72  can be driven by means of the electric motor  28 . In detail, the electric motor  28  is coupled to the spindle drive  72  for drive purposes via the wheel gear mechanism  58  and the planetary gear stage  48 . 
     An actuating slide  88  is mounted on the spindle  84  and configured as a piston-like spindle nut. 
     Rotation of the spindle  84  causes an axial displacement of the actuating slide  88  along the centre axis  50 . 
     The actuating slide  88  is here guided along the centre axis  50  on a running face  90 , wherein the running face  90  is formed on an inside of the guide part  70 . The running face  90  substantially corresponds to a cylinder casing surface forming the inner circumference of the guide part  70 . In other words, the actuating slide  88  is mounted in the guide part so as to be linearly displaceable. 
     Furthermore, the actuating slide  88  is prevented from relative twisting about the centre axis  50  by means of a rotational locking device  92  which is formed as a slot on the guide part  70 . For this, a rotational locking element  94  which engages in the slot is arranged on the actuating slide  88  (see  FIG.  1   ). The rotational locking element  94  in this exemplary arrangement is a radial protrusion. 
     The actuating slide  88  serves for applying a first brake pad  96  of a brake jaw assembly  98  to the brake disc  19 . In other words, due to the actuator assembly  10 , the first brake pad  96  can be actively moved towards a brake disc  19 , formed as a disc in the exemplary arrangement illustrated. 
     In detail, due to the electric motor  28 , the actuating slide  88  is transferred optionally, via the wheel gear mechanism  58 , the planetary gear stage  48  and the spindle drive  72 , into an extended position assigned to application of the first brake pad  96  on the brake disc  19 . 
     Because of the reaction forces acting inside the actuator assembly  10  and the brake jaw assembly  98 , a second brake pad  102  is thereby also applied to the brake disc  19 . 
     It is clear that the actuating slide  88  can be moved in the same way, by operation of the electric motor  28 , into a retracted position which is assigned to a lifting of the first brake pad  96  and the second brake pad  102  from the brake disc  19 . 
     In the present exemplary arrangement, the actuator assembly  10  is designed without self-inhibition so that, because of system-inherent elasticities, the actuating slide  88  also automatically moves back into the retracted position when no longer actively loaded into the extended position by the electric motor  28 . 
       FIG.  4    shows an actuator assembly  10  according to a further exemplary arrangement. 
     In the description below, the same reference signs are used for identical structures with the same functions as known from the above exemplary arrangement, and to this extent reference is made to the preceding explanations, wherein only the differences between the respective exemplary arrangements will be discussed below so as to avoid repetition. 
     The actuator assembly  10  according to  FIG.  4    differs from the actuator assembly  10  according to  FIGS.  1  to  3    in that the guide part  70  is not formed as a separate bearing sleeve but is formed integrally in the brake caliper  15 . 
     More precisely, the guide part  70  is formed by a sleeve-like portion of the brake caliper  15 . 
     Accordingly, the rotational locking geometry  82  is formed on the brake caliper  15 , namely on an outer wall  83  of the brake caliper in the region of the sleeve-like portion  70 . 
     In addition, the rotational locking device  92  is also different. 
     An opening  116  is provided in the brake caliper  15  in the region of the guide part  70 . A rotational locking element  118  is inserted in the opening  116  and protrudes through the opening  116  to engage in an axially running groove  120  on the actuating slide  88 . 
     In the exemplary arrangement shown, the rotational locking element  118  is a screw which is screwed into a threaded bore forming the opening  116 . 
     Further exemplary arrangements have the common feature that the guide part  70  is open towards the space  17  so that the actuating slide  88  can be moved into the space  17 .