Patent Publication Number: US-8534101-B2

Title: Electronic unlatch system for vehicle door

Description:
BACKGROUND OF INVENTION 
     The present invention relates generally to vehicle doors and more particularly to key and latch systems for access from the outside of a vehicle door. 
     Some automotive vehicles now employ electronic door systems where the door handle is electronically linked to the door latch, rather than mechanically linked. Thus, an electronic latch is employed that is powered by the vehicle electrical system and electronically controls the unlatching of the door. With the conventional mechanical linkages driven by movement of the door handle eliminated, a backup system is needed to allow for door opening when the main power from the vehicle electrical system is interrupted. These backup systems typically involve running a cable, attached to an emergency release on the latch, to a cargo area, such as a trunk. Then, if the main vehicle power is interrupted, one can open the trunk and pull on the cable to mechanically cause the latch to open. However, all of the extra cable and linkages are undesirable. 
     SUMMARY OF INVENTION 
     An embodiment contemplates a vehicle door having an electronic unlatch system. The door includes an electronic key cylinder mounted to the door and including a slot configured to receive a key; a switch operatively engaging the electronic key cylinder to detect when a key has been turned in the key cylinder; and a door latch mounted to the door and configured to selectively unlatch the door, with the door latch configured to receive a signal from the switch to unlatch the door. The door also includes a backup power supply mounted in the door and configured to supply electrical power to the door latch and switch, with the backup power supply configured to receive power from a vehicle electrical system to recharge the backup power supply. 
     An embodiment contemplates a method of unlatching a vehicle door having an electronic unlatch system, the method comprising the steps of: charging a backup power supply, mounted in the door, with a vehicle electrical system; activating a switch by inserting and turning a key in an electronic key cylinder in the door; sending a signal from the switch to a door latch requesting unlatching of the door; and using power from the backup power supply to power the door latch to unlatch the door. 
     An advantage of an embodiment is that the electronic unlatch system allows for unlocking and opening a vehicle side door without the use of a mechanical backup system, even when the main vehicle power is interrupted. This allows elimination of a mechanical backup system, which may allow for a reduction in the number of components, simplify vehicle assembly, save weight and improve vehicle packaging. Also, the operation of a key in the electronic unlatch system allows for both unlocking and unlatching the door when the vehicle power is interrupted, thus allowing one to enter the vehicle through the side door during power interruptions. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a portion of an electronic unlock system in a vehicle. 
         FIG. 2  is a perspective view of an outside door handle mounted on a vehicle door. 
         FIG. 3  is a perspective view of the outside door handle showing the side that mounts to the vehicle door. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-3 , a portion of a vehicle door  20  is shown. This may be, for example, a driver&#39;s side door. The vehicle door  20  includes a door outer panel  22  having a handle depression  24  creating a recess in an outer surface  26  of the outer panel  22 . An outside door handle  28  mounts to the door  20  adjacent to the handle depression  24 . 
     The outside door handle  28  has a hand grip portion  30  extending between a pair of door mounting portions  32 . A touch pad  40  is exposed on an inside surface of the hand grip portion  30 . Touch pad wiring  48  connects the touch pad to a door latch  46  that can be electronically actuated to unlatch the door  20 , allowing the door  20  to open. A bore  34  for receiving an electronic key cylinder  36  extends through one of the mounting portions  32 . The electronic key cylinder  36  mounts in and includes a key slot  38  that is accessible from the outside of the vehicle through the bore  34 . A key  56  includes a blade portion  58  that fits within the key slot  38  and a key head portion  60  that includes electronics  62  embedded within it. 
     The electronic key cylinder  36  is part of an electronic unlatch system  37  and is attached to a switch  42  having verification electronics  44  therein that allow for verification, encryption and transmission of a signal from the switch  42  to the door latch  46  via key cylinder wiring  50 . The electronics  44 ,  62  may be any combination of hardware and software and electronics for performing such functions and is known to those skilled in the art. 
     The signal from the switch  42  can cause the latch  46  to unlatch the door  20 . The latch  46  includes a backup power supply  52  that may be mounted within, mounted on or mounted adjacent to the latch  46  in the door  20 . The backup power supply  52  may be a rechargeable battery, a capacitor or other type of power storing device. The latch  46  and the backup power supply  52  are powered from the vehicle electrical system  54 , which may include a vehicle battery, alternator, etc., as is known to those skilled in the art. In the case of the latch  46 , the electrical system  54  provides power to operate the latch  46  and touch pad  46  during normal vehicle operation. In the case of the backup power supply  52 , the electrical system  54  provides power to charge the power supply  52  during normal vehicle operation so that stored energy is available should electrical system power be lost. 
     The operation of the electronic unlatch system  37  will now be discussed. Under normal operating conditions, a person contacting the touch pad  40  will send a signal to unlatch the door latch  46  if the door is unlocked. The power for the touch pad  40  and door latch  46  is supplied by the vehicle electrical system  54 . Unlocking the door under normal operating conditions can be initiated by a key fob (not shown) or other known means for unlocking the door. Also, under normal operating conditions, the backup power supply  52  recharges with power taken from the vehicle electrical system  54 , thus remaining charged at all times. 
     There may be times, however, when the side door  20  is locked and closed and the power from the vehicle electrical system  54  is interrupted. This may occur, for example, when the vehicle battery is dead and the vehicle is off. In this situation, the key fob (or other unlocking) system and the door latch  46  can no longer be powered by the vehicle electrical system  54 . One then inserts an appropriate key  56  in the key slot  38  and attempts to turn it. The key cylinder  36  allows it to turn if the teeth on the key blade  58  match the key cylinder  36 . This rotation closes the switch  42 , which activates the verification electronics  44 . The verification electronics  44  is powered by the backup power supply  52  in the door latch  46 . The verification electronics  44  initiates a wireless challenge/response verify operation with the electronics  62  in the key head  60  to determine if the key  56  is approved for unlocking the door  20 . Once the key  56  is verified, the verification electronics  44  sends an encrypted signal to the door latch  46  to unlock and unlatch the door  20 . The door latch  46 , receiving power from the backup power supply  52 , will unlock and unlatch the door  20 . Thus, one will be able to enter the vehicle, even when the main power of the vehicle electrical system  54  is not available. 
     While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.