Patent Publication Number: US-2023151862-A1

Title: Actuator assembly for a vehicle brake

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Priority Application No. 102021129964.0, 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 a vehicle brake, with a brake calliper and an actuating slide for a brake pad which is guided linearly in the brake calliper. 
     The actuating slide can be moved optionally between a retracted position and an extended position, and serves to move a brake pad. In one exemplary arrangement, the brake pad may be applied to a brake disc by the actuating slide. 
     BACKGROUND 
     Usually, a guide sleeve is provided for linear guidance of an actuating slide, wherein the actuating slide is received and guided linearly in said guide. The use of a guide sleeve however leads to increased cost in production of the actuator assembly. 
     What is therefore needed is simple and economic arrangement of a stable guidance of the actuating slide. 
     SUMMARY 
     An actuator assembly for a vehicle brake is disclosed, with a brake calliper in which a space is formed for a brake disc, and an actuating slide for a brake pad, wherein the actuating slide can be moved optionally between a retracted position and an extended position. In the brake calliper, adjoining the space, a sleeve-like portion is formed with a running face for the actuating slide, wherein the actuating slide is received in the sleeve-like portion and is guided linearly on the running face. 
     According to the disclosure, the sleeve-like portion is formed integrally in the brake calliper. 
     Because the running face for the actuating slide is formed in the brake calliper, this achieves an advantage that no separate guide sleeve is required. This arrangement reduces the number of components, thereby reducing both production costs and also installation complexity. 
     The brake calliper is usually a casting and thus has the necessary stability to guarantee a stable guidance of the actuating slide. 
     In one exemplary arrangement, the running face of the brake calliper is machined to ensure that the actuating slide can slide as smoothly as possible. 
     According to one exemplary arrangement, the actuator assembly comprises an electric motor which is coupled for drive purposes to the actuating slide via a gear unit and a spindle drive, in order to move the actuating slide between the retracted position and the extended position. In one exemplary arrangement, the actuator assembly is accordingly an electromechanical actuator assembly. An electric motor may generate a sufficiently high force to apply a brake pad to a brake disc by the actuating slide. 
     In one exemplary arrangement, the sleeve-like portion is open towards the space. The actuating slide can accordingly be moved into the space, in order to move the brake pad which is arranged in the space. 
     In one exemplary arrangement, an opening is present in the brake caliper in the region of the sleeve-like portion, and a rotational locking element protrudes through the opening. The rotational locking element engages in an axially running groove on the actuating slide. The groove runs in a displacement direction of the actuating slide. The rotational locking element allows the actuating slide to be easily mounted in the sleeve-like portion in a rotationally fixed fashion. 
     For example, in one exemplary arrangement, the rotational locking element is a screw, a bolt or similar. Such elements are cheap and easily available. 
     In one exemplary arrangement, the opening can be created easily by a bore from an outside of the brake calliper into the interior of the sleeve-like portion. 
     In one exemplary arrangement, on an end facing away from the space, the sleeve-like portion has a wall which runs transversely to a movement direction of the actuating slide, wherein the spindle drive rests axially on the wall. In this way, an axial force, which builds up during application of the brake pad on the brake disc, is transmitted to the wall via the actuating slide and the spindle drive. In other words, the wall forms an abutment for the actuating slide during application of the brake pad on the brake disc. Because the abutment is integrated in the brake calliper, a compact construction of the actuator assembly is achieved. 
     The support on the wall may take place either directly or indirectly via an additional bearing. Support via an additional bearing has the advantage of reducing a friction during rotation of the spindle drive. 
     In one exemplary arrangement, an opening is present in the wall, wherein a shaft of the spindle drive extends through the opening and the shaft is coupled to the gear unit outside the sleeve-like portion. The opening accordingly guarantees the accessibility of the spindle drive for drive purposes. 
     According to one exemplary arrangement, a rotational locking geometry is formed on an outer wall of the brake calliper in the region of the sleeve-like portion for form-fit connection of the brake calliper to a frame part of a carrier assembly. Such a rotational locking geometry allows a stiff connection between the frame part and the brake calliper, so that a reliable force transmission to the actuating slide is guaranteed. 
     For example, fixing interfaces for the electric motor and a receiving space for the gear unit are formed on the frame part. 
     In one exemplary arrangement, the rotational locking geometry is a splined shaft geometry. The brake calliper and the frame part can easily be joined together by an axial push-fit movement. 
     A recess for a seal may be provided on an inside of the brake calliper at the transition from the space to the sleeve-like portion. If a seal is inserted in the recess, the gear unit and the spindle drive are sealed against the space, preventing dirt particles or abrasion from the brake pads from entering the gear unit. 
    
    
     
       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 a sectional illustration of an actuator assembly according to the disclosure, 
         FIG.  2    shows a drive assembly for the actuator assembly according to the disclosure, and 
         FIG.  3    shows a frame part of the actuator assembly according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows an actuator assembly  10  for a 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 , which tightly closes the housing base part  18  in fitted state. 
     In the exemplary arrangement shown, the housing cover  20  is also substantially dish-shaped. 
     In one exemplary arrangement, 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 calliper  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 calliper  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 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 . 
     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 particularly 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 the brake calliper  15  received therein. The fixing interface  68  can be seen in  FIG.  3   , which shows the frame part  24  in a perspective view. 
     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 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 , which also may have a splined shaft geometry, is provided at the end of the brake calliper  15  to be coupled to the second fixing interface  68 . 
     The brake calliper  15  may accordingly slide along the centre axis  50  into the rotational locking geometry  74  of the second fixing interface  68  where it is held rotationally fixedly by form fit. 
     As  FIG.  1    shows, the brake calliper  15  comprises, as well as the space  17  for the brake disc  19 , a sleeve-like portion  70 . 
     The rotational locking geometry  82  is formed on an outer wall  83  of the brake calliper  15  in the region of the sleeve-like portion  70 . 
     The sleeve-like portion  70  is open towards the space  17 . 
     A spindle drive  72  is received in the interior of the sleeve-like portion  70 . 
     This comprises a spindle  84 , in the present case configured as a recirculating ball spindle. 
     The spindle  84  is rotationally fixedly connected to the planet carrier  66  via a toothing portion  86  (see  FIG.  1   ). 
     Thus the spindle drive  72  can be driven by 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. The actuating slide  88  is accordingly also received in the sleeve-like portion  70 . 
     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 sleeve-like portion  70 . The running face  90  substantially corresponds to a cylinder casing surface forming the inner circumference of the sleeve-like portion  70 . 
     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, by 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, by 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 case, 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 . 
     In order to absorb the resulting counter-forces from actuation of the brake jaw assembly  98 , at an end facing away from the space  17 , the sleeve-like portion  70  has a wall  104  which runs transversely to a movement direction of the actuating slide  88 . 
     The spindle drive  72  rests axially on the wall  104 , for example via a bearing  106 . 
     An opening  108  is provided in the wall  104 , through which a shaft  110  of the spindle drive  72  extends. 
     The toothing portion  86  is formed on the shaft  110 . 
     The shaft  110  is coupled to the gear unit  67  outside the sleeve-like portion  70 . 
     A recess  112  for a seal  114  may be provided on an inside of the brake calliper  15  at the transition from the space  17  to the sleeve-like portion  70 . 
     This seal  114  is formed as a bellows and held not only on the brake calliper  15  but also on the actuating slide  88 , so that the seal  114  is expanded or compressed when the actuating slide  88  moves. 
     Furthermore, an opening  116  is provided in the brake caliper  15  in the region of the sleeve-like portion  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 .