Abstract:
An electric device for operating vehicle brakes using a pulling element and an operating motor with a rotatable driving axis. The device includes a centrifugal assembly with rotatable parts which are radially outwardly movable due to centrifugal forces. The centrifugal assembly also comprises at least one translational element, which is disposed so that it is capable of axial movement that is related to the rotational speed of the driving axis. The axial movement of the translational element translates to movement of the pulling element. Several implementations provide reduced power consumption and less friction and heat losses.

Description:
RELATED APPLICATIONS  
       [0001]     The present application claims priority under 35 USC §§ 119 and 365 to commonly owned and assigned Application No. PCT/EP2003/014072, filed Dec. 11, 2003 entitled Device for Operating Vehicie Brakes, which claims priority to German application 102 57 865.6 filed Dec. 11, 2002, both of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to vehicle brakes. More specifically, the present invention relates to devices for operating vehicle brakes.  
       BACKGROUND OF THE INVENTION  
       [0003]     Braking systems are known to be used in motor vehicles as parking brakes (handbrakes) so that the vehicle cannot unintentionally move in the parked state.  
         [0004]     Devices are known that use both an electric motor and a corresponding gear to apply the vehicle brakes. These known devices, however, have the disadvantage that they are noisy and that they cause a comparatively high power consumption. Furthermore, the gear can become comparatively hot and there are disadvantageous friction effects. A device of this kind is disclosed and described in the WO 98/56633.  
         [0005]     Although present devices are functional, they are not sufficiently accurate or otherwise satisfactory. Accordingly, a system and method are needed to address the shortfalls of present technology and to provide other new and innovative features.  
       SUMMARY OF THE INVENTION  
       [0006]     According to one embodiment, the invention may be characterized as a device for operating vehicle brakes using a pulling element connected with the vehicle brakes and an operating motor comprising a rotating driving axis. The device according to this embodiment comprises a centrifugal arrangement which is in operating connection with the mentioned driving axis and which comprises a translational element. The translational element is formed such that it can perform an axial movement related to the rotational speed of the driving axis. Finally, the translational element is coupled to the mentioned pulling element for operating the vehicle brake.  
         [0007]     According to several embodiments, the rotational movement of a preferably electrical driving motor is utilized to create a centrifugal movement of parts or arms hingedly connected to the driving motor, which is transformed into an axial movement, wherein this axial movement is used for operating the brakes.  
         [0008]     The present invention reduces the power consumption of the electric motor, since a comparatively low torque is necessary. Furthermore, there are no high friction creating parts, like gears, present. Accordingly, no gear noises are created by the device according to the invention. Finally, there are no disadvantageous heating effects. The rotating parts provide additionally a ventilating effect. Furthermore, the device according to the invention operates reliably and with reduced wear.  
         [0009]     In variations, a decoupling device is implemented for decoupling the rotating centrifugal arrangement from the pulling element, so that the pulling element is not rotated, wherein the decoupling device is arranged between the centrifugal assembly and the pulling element.  
         [0010]     According to another embodiment, it is particularly advantageous to construct the decoupling device as an axially guided slide and as a pivot bearing arranged on the slide, wherein the pivot bearing is an axial and a radial bearing. Thereby, the rotational movement is decoupled with comparatively low noise and friction. Thus, abrasion is considerably reduced.  
         [0011]     The device according to yet another embodiment of the invention comprises a blocking assembly operable by actuators so that the operating motor has not to be operated continuously, for example, if the vehicle is parked, wherein the actuators are provided such that they can block the axial movement of the translational element.  
         [0012]     In accordance with one variation, a blocking device that is secure and easy to manufacture is obtained when the blocking assembly comprises at least two blocking arms hinged on one side at rotational bearing points, each having a clamping region, wherein at least one blocking element connected to the slide is arranged between the blocking arms so that it can be fastened, wherein the mentioned actuators act on the blocking arms and are each arranged on the end of the blocking arms opposite to the rotational bearing points. Additionally, this embodiment leads to a compact construction.  
         [0013]     The actuators in one embodiment are realized by electromagnets, which can open the blocking arms against the spring force of pulling ends arranged at the ends opposite to the rotational bearing points of the blocking arms. Thus, the actuators can be electrically controlled. Alternatively, the actuators can also be provided as clutch spring brakes.  
         [0014]     In accordance with one variation, which is relatively easy to manufacture, the centrifugal assembly comprises a shaft connectable to the rotating axis of the operating motor and at least two rotating arms, hinged to the shaft, each having corresponding weights at their free ends and each a first bearing point and at least two pulling arms, which are respectively flexibly connected with one end thereof to a second bearing point, wherein the second bearing point is arranged at the rotating arm between the weight and the first bearing point of the respective rotating arm and which are respectively fixed with the other end to a slide at a third bearing point. Thereby, the slide is axially displaceable arranged at the mentioned shaft and a pulling spring is arranged between the respective second bearing point and the shaft.  
         [0015]     In yet another variation, the operating motor, the centrifugal assembly, the decoupling device and the blocking assembly are arranged in a common housing as a single unit, which results in a particularly compact construction.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     Exemplary embodiments of the present invention that are shown in the drawings are summarized below. These and other embodiments are more fully described in the Detailed Description section. It is to be understood, however, that there is no intention to limit the invention to the forms described in this Summary of the Invention or in the Detailed Description. One skilled in the art can recognize that there are numerous modifications, equivalents and alternative constructions that fall within the spirit and scope of the invention as expressed in the claims.  
         [0017]      FIG. 1 a  cross-section of the device according to the invention for operating vehicle brakes according to an embodiment of the present invention; and  
         [0018]      FIG. 2 a  schematic presentation of the operation of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0019]     The device according to several embodiments of the present invention comprises an electric motor as operating motor  3 , as shown on the left side in  FIG. 1 . The rotatable driving axis  4  of the motor is directly coupled to a shaft  17 . The shaft  17  has a bearing on its two ends in a housing  25 . A centrifugal assembly  5  is arranged at the shaft  17  close to the operating motor  3 . The centrifugal assembly  5  has a symmetric construction and includes, on each side, a rotating arm  18 , a pulling arm  21 , a pulling spring  24  and a guidance coupled to a slide  9 .  
         [0020]     A bearing point  20  is respectively arranged at the shaft  17 , rotating with the shaft  17 . To this bearing point  20 , a rotating arm  18  is rotatably supported. At the other end of the rotating arm  18 , a weight  19  is present, which is formed such that the rotating arm  18  is in this part thicker or has a greater mass. A second bearing point  22  is arranged approximately in the center between the free end and the hinged end of the rotating arm  18 , which is connected with a pulling arm  21 . A pulling spring  24  is arranged between the shaft  17  and the second bearing point  22 , which pulls the bearing arm  18  to the shaft  17 . The other end of the pulling arm  21  is connected to a third bearing point  23  which is movable in parallel to the axis of the shaft  17 .  
         [0021]     A slide  9  is connected to the third bearing point  23  which is axially slidably arranged over the shaft  17 . Some parts of the slide  9  are rotating together with the centrifugal assembly. Other parts of the slide  9  are decoupled from this rotating movement. Thereby, the slide  9  acts as a decoupling device  8 . It comprises a fixed pivot bearing  10  and is axially guided. The pivot bearing  10 , which is an axial and radial bearing, ensures that the pulling element  2  is not rotated but exclusively pulled or axially moveable. Thus, the pulling element  2  is connected to the slide  9  such that it is attached to a non-rotating part.  
         [0022]     Furthermore, the device  1  comprises a blocking assembly  11  which can axially fasten or hold the slide  9  and thereby the pulling element  2 . The blocking assembly  11  is also symmetric and includes, on each side, a blocking arm  12  which is supported at one side at the housing  25 , respectively at the bearing point  15 . The bearing point  15  is arranged close to the operating motor  3 . A second pulling spring  16  is arranged at the other end, which pulls the blocking arm  12  in the direction of the slide  9 . An electromagnet or an actuator  27  acts against the spring force of the second pulling spring  16 . This actuator can also be provided as a clutch spring brake. In the area of the slide  9  the blocking arm  12  comprises a clamping region  13 , which can be pressed against the blocking element  14 , wherein the blocking element  14  is connected to the slide  9 .  
         [0023]     As depicted in  FIG. 1 , at least one translational element  7 , which can also be the slide  9 , is axially movable and axially guided and that rotatable parts  6  are present, as the rotating arms  18  with their weights  19 , which are radially outwardly movable due to the centrifugal force. In this embodiment, the higher the rotating speed of the shaft  17 , the higher the linear deflection of the translational element  7 .  
         [0024]     The device  1  according to the exemplary embodiment of the invention operates as follows:  
         [0025]     The vehicle brakes are connected to an end of the pulling element  2 , the end of which is not shown. The vehicle brakes pull with a certain spring force on the pulling element  2 . To operate the vehicle brakes, this spring force must be exceeded.  
         [0026]     When starting from a released state of the pulling cable  2 , the slide  9  is positioned slightly more to the right than shown in  FIG. 1 . Although the pulling element  2  is in a released state, it should be recognized that the pulling element may have a certain pretension without operating the vehicle brakes The blocking arms  12  keep the slide  9  in this position. The operating motor  3  is still turned off.  
         [0027]     If the parking brake is to be applied, the actuators  27  (e.g., electromagnets) are activated so that the blocking arms  12  open and the slide  9  is released. Simultaneously or subsequently, the operating motor  3  is activated or controlled, so that the shaft  17  is rotated. With increasing speed of the rotation, the weights  19  are pushed to the outside due to the centrifugal force. The forces of the pulling springs  24  are acting against the centrifugal force. The opening movement of the rotating arms  18  causes, via the pulling arms  21  (which are connected to the rotating arms  18 ), the slide  9  and the pulling cable  2 , to be moved in the direction of the operating motor  3 . Since the friction losses are comparatively low, electric power is applied to start the rotation of the rotating parts  5 , but once the parts  5  are rotating, little or no additional electric energy is necessary. When the parts are rotating, the operating motor  3  needs comparatively little power.  
         [0028]     When the slide  9  or the pulling element  2  has been pulled in the direction of the operating motor, the actuators  27  can be deactivated so that the blocking arms are closing again and the slide  9  is once again held in a fastened position. The operating motor  3  can then be turned off.  
         [0029]     For a smooth or soft release of the parking brake, the operating motor  3  is started before the blocking arms  12  are opened again. By controlling or adjusting the operating motor  3 , the pulling element  2  is moved back into the release position of the vehicle brake in a controlled manner. The pulling element  2  can be held with an optimal pretension, and if this pretension is achieved, the blocking arms  12  can close again and the operating motor  3  can be turned off again.  
         [0030]     In the exemplary embodiment, all elements of the device  1  are arranged in a common housing  25  as a single unit. The arrangement shown in  FIG. 1  is comparatively compact.  
         [0031]      FIG. 2  shows a schematic representation to illustrate the decoupling of a rotational movement. Between the operating motor  3  and the centrifugal assembly  5  the rotational movement is decisive. Between the centrifugal assembly  5  and the decoupling device  8  an axial movement is already present, wherein the rotational movement is still present. No rotational movement is present between the pulling cable  2  and the decoupling device  8  so that the pulling element  2  is not rotated.  
         [0032]     In this example, the pulling element  2  is a Bowden cable.  
         [0033]     The invention is not limited to the described embodiment but comprises also other equivalent embodiments. For example, the pulling element  2  can be in an extreme case directly arranged with two pulling cables at the rotating arms  18 , wherein the pulling element  2  can rotate within the housing  25 . The decoupling of the rotational movement can also take place outside the device  1 .  
       List of Reference Signs  
       [0000]    
       
           1  device  
           2  pulling element  
           3  operating motor  
           4  driving axis  
           5  centrifugal assembly  
           6  rotatable parts  
           7  translational element  
           8  decoupling device  
           9  slide  
           10  pivot bearing  
           11  blocking assembly  
           12  blocking arms  
           13  clamping region  
           14  blocking element  
           15  rotational bearing points  
           16  pulling springs  
           17  shaft  
           18  rotating arms  
           19  weight  
           20  first bearing point  
           21  pulling arms  
           22  second bearing point  
           23  third bearing point  
           24  pulling springs  
           25  housing  
           27  actuators