Abstract:
An electrically controlled parking brake for motor vehicles, including an operating element for operating the parking brake and a control unit, which controls an actuator of the parking brake when the operating element is operated. The parking brake function is ensured, upon failure of the electrical supply, if the parking brake includes a connecting device for connecting an auxiliary voltage source, with the aid of which the parking brake may be operated in an auxiliary manner.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an electrically driven parking brake for motor vehicles.  
       BACKGROUND INFORMATION  
       [0002]     A parking brake is used especially to secure a parked vehicle from rolling away. According to regulations in force, the vehicle is held in place mechanically and without energy being applied when the parking brake is applied. Normally, this is implemented by a mechanical locking device.  
         [0003]     Electrically operated parking brakes include an operating element, such as a push button, for operating the parking brake. A control unit connected to the operating element detects a parking brake command and accordingly activates an actuator, such as an electric motor or a hydraulic pump, in order to apply the parking brake or to release it. In a hydraulic or pneumatic parking brake system, the brake may be locked by a mechanical locking device, so that the vehicle is held in place without the application of energy. The locking device may be operated by hydraulic or pneumatic pressure. In this context, it is necessary to control magnetic valves electrically.  
         [0004]      FIG. 1  shows such a parking brake system, known from other systems, in a schematic representation. The parking brake includes an operating element  7  (push button), a control unit  6  and a hydraulic unit  5 . When operating element  7  is operated, the control unit activates hydraulic unit  5 , or, more accurately, an hydraulic pump which generates pressure in a hydraulic line  9 , which is used both for operating wheel brake  11  and for operating a locking device  12 . The parking brake also includes a hydraulic valve  10  which is activated by control unit  6  in order to lock or to release locking device  12 .  
         [0005]     The system is supplied with current from the vehicle electrical system by a battery  8 . When the electrical energy supply fails, it is no longer possible to lock the parking brake (in order, for example, to park the vehicle safely), or to release the parking brake if the vehicle is parked (in order, for example, to tow it away), since valve  10  may no longer be activated.  
       SUMMARY OF THE INVENTION  
       [0006]     It is an object of the present invention to create a device with the use of which the parking brake may be operated even during failed energy supply.  
         [0007]     The present invention provides, for a parking brake system, a connecting device for connecting an auxiliary voltage source with which the parking brake is able to be operated on an auxiliary basis if the electrical supply fails. Thereby the parking brake may be locked or released using on-board arrangement, such as a battery, even if there is a total breakdown of the vehicle electrical system.  
         [0008]     According to a first exemplary embodiment of the present invention, the connecting device includes terminal contacts to connect an auxiliary battery (i.e. one or more 1.5V or 9V batteries). In this exemplary embodiment, the battery may be connected directly to the terminal contacts. This may provide that no further auxiliary arrangement, such as, for instance, a battery adapter, are required.  
         [0009]     According to a second exemplary embodiment of the present invention, the connecting device includes a battery adapter which, for example, is able to be plugged into a plug connection. In the case of the battery adapter according to the present invention, especially a device is involved into which a battery is inserted or into onto which it may be plugged. The battery adapter, for example, may be configured in such a manner that it may be able to be plugged onto a plug connector of a cable harness of the vehicle, such as the control unit cable harness.  
         [0010]     According to a third exemplary embodiment of the present invention, the connecting device includes a terminal contact for connecting a cable such as a battery jumper cable or the cable of an external starting device. The terminal contact may be, in this instance, configured in such a manner that the cable may simply be clamped on, and includes, for example, the shape of a lug.  
         [0011]     The connecting device according to the present invention may be arranged, for example, in the engine compartment, for example, on the control unit of the parking brake. However, the connecting device may be arranged in the passenger compartment. This may provide that a battery may conveniently be plugged into it by the driver.  
         [0012]     The auxiliary battery (with or without adapter) may also be permanently connected to the parking brake system. A switch operated by the driver in an emergency may, for instance, be provided for switching on or off the auxiliary energy supply. The failure of the energy supply may also be detected automatically, and the energy supply may be activated automatically via the auxiliary battery, if an appropriate sensor system and circuit are provided.  
         [0013]     The connecting device for the auxiliary voltage source may be electrically connected in such a manner that at least the valve for locking or releasing the parking brake may be supplied with auxiliary energy. In particular while using a battery, the remaining electrical system of the vehicle may not be supplied with auxiliary energy.  
         [0014]     The connecting device may also be set up in such a manner that, during normal operation, no vehicle electrical system voltage is present at the contacts of the connecting device. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  shows a schematic basic circuit diagram of an electrically controlled parking brake according to other systems.  
         [0016]      FIG. 2  shows a connecting device for connecting an auxiliary voltage source according to a first exemplary embodiment of the present invention.  
         [0017]      FIGS. 3   a - c  shows a connecting device for connecting an auxiliary voltage source according to a second exemplary embodiment of the present invention.  
         [0018]      FIG. 4  shows a connecting device for connecting an auxiliary voltage source according to a third exemplary embodiment of the present invention.  
         [0019]      FIG. 5  shows a connecting device for connecting an auxiliary voltage source according to a fourth exemplary embodiment of the present invention.  
         [0020]      FIGS. 6   a  and  6   b  shows a connecting device for connecting an auxiliary voltage source according to a fifth exemplary embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0021]     Reference is made to the introductory part of the specification regarding the clarification of  FIG. 1 .  
         [0022]      FIG. 2  shows a cutout of a parking brake system, including a control unit  6 , which is connected to a valve  10  via a control line. For the purpose of releasing or locking the parking brake, valve  10  is controlled by control unit  6 . In normal operation, control unit  6  is supplied with electrical energy from the vehicle&#39;s electrical system by vehicle battery  8 . When there is a failure of the electrical energy supply, such as based on a defective vehicle battery  8 , valve  10  may no longer be operated, and consequently the parking brake may no longer be released or locked. In order to secure emergency operation even in this case, the control unit includes a connecting device including two terminals  21  for connecting an auxiliary battery  20 . The auxiliary battery  20  may be, for instance, several 1.5V batteries or one commercial 9V battery which may be plugged onto terminals  21 . The battery may, for instance, be added to the vehicle&#39;s tool set.  
         [0023]     Terminals  21  are connected electrically inside control unit  6  in such a manner that valve  10 , which is necessary for the operation of locking device  12 , may be supplied directly with current. Additional users, e.g., the vehicle&#39;s electrical system, are not supplied with auxiliary energy in this context. Terminals  21  are furthermore connected in such a manner that, in normal operation, electrical system voltage is not present at them. The corresponding connection may, for example, be implemented by semiconductor switches such as transistors or diodes. The connection is represented symbolically by a switch  28 .  
         [0024]     The pressure required for locking or releasing the parking brake may be built up by the driver of the vehicle by operating brake pedal  1  (see  FIG. 1 ), and the parking brake may be appropriately released or locked.  
         [0025]      FIGS. 3   a - 3   c  show a exemplary embodiment of the present invention in which a battery adapter  22  is plugged onto a plug connector  29  of the vehicle&#39;s cable harness  27 , in order to supply the parking brake with auxiliary energy.  
         [0026]      FIG. 3   a  shows control unit  6  of the parking brake together with a vehicle cable harness  27  connected to it. In order to connect adapter  22 , cable harness  27 , as shown in  FIG. 3   b , is pulled away (unplugged) from control unit  6 . Adapter  22  may then be plugged onto plug connector  29  of vehicle cable harness  27  (see  FIG. 3   c ).  
         [0027]     Battery adapter  22  includes a battery  20  on the inside of adapter  22  (auxiliary battery  20  could also be plugged on the outside). Battery adapter  22  is connected in such a manner that, by plugging on adapter  22 , valves  10  which is necessary for locking or releasing the parking brake, are directly supplied electrically. The driver of the vehicle is able to operate locking device  12  by appropriate pressure buildup via brake pedal  1 , and is consequently able to lock or release the parking brake. The cable harness adapter including an exchangeable battery may be put with the vehicle&#39;s tool kit.  FIG. 4  shows an additional exemplary embodiment of the present invention, in which the connecting device is configured as connector  23  for clamping on a cable. An external voltage source, such as an external starting device, a 12V vehicle battery or a power pack may therefore be connected in a manner with the aid of a cable.  
         [0028]     Terminal  23  may be connected in such a manner that the components of the parking brake system, especially control unit  6 , hydraulic unit  5  and valves  10  are supplied with auxiliary energy. The driver is therefore in a position to lock or release the parking brake in the customary manner, by operating operating element  7  in the vehicle&#39;s interior. The remainder of the electrical system may not be supplied with auxiliary energy. This may provide that the parking brake still functions even when serious defects or short circuits are present in the vehicle&#39;s electrical system, and connecting the external starting device to the electrical system with the aid of a battery jumper cable is no longer possible.  
         [0029]     The electrical connection inside control unit  6 , which is shown symbolically by a switch  28 , is able to be implemented using a diode device.  
         [0030]      FIG. 5  shows a connecting device corresponding to  FIG. 1 , which, however, may be operated from the passenger compartment. For this purpose, a connecting part  24  including terminals  21  is arranged in the passenger compartment. Connecting part  24  is connected to control unit  6  and valve  10  via lines  26 , in order to supply valve  10  with current in an emergency operation.  
         [0031]      FIGS. 6   a ,  6   b  show a exemplary embodiment of the present invention in which the connecting device is implemented in the form of an adapter plug  25  that is additionally connected to cable harness  27 , onto which adapter  22  is plugged. Adapter plug  25  is connected via lines  26  to cable harness  27 , and is wired in such a manner that a valve  10  is electrically supplied in response to the connection of an auxiliary voltage source.  
         [0032]     In normal operation, plug adapter  25  is protected by a cap  30 . When the electrical supply fails, cap  30  may be pulled off and a battery adapter  22  is plugged onto plug connector  25  (see  FIG. 6   b ), in order thus to make possible the operation of the parking brake.  
         [0033]     Connecting device  22 ,  25  is in this case connected in such a manner that only valve  10 , and not control unit  6  is supplied with current. The plug connector  25  may be arranged in the passenger compartment. Thereby, in particular, the driver is not forced to disconnect cable harness  27  from control unit  6 , as is required in the exemplary embodiment of  FIG. 3 .