A fuel door and a sliding door are on the same side of a vehicle. The sliding door has power locking and power child locking. To prevent the sliding door from interfering with the fuel door during refueling, a lock controller responds to the fuel door moving to the open position by 1) preserving a current outside locked or unlocked state and a current inside locked or unlocked state of the sliding door, 2) initiating or maintaining the outside locked state and inside locked state, and 3) after the fuel door moving to the closed position, restoring or maintaining the preserved current outside locked or unlocked state and the preserved current inside locked or unlocked state.

CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a divisional application of U.S. Ser. No. 13/160,650, filed Jun. 15, 2011. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates in general to passenger sliding door operation for transportation vehicles, and, more specifically, to preventing collision between a sliding door and a fuel door adjacent to the sliding door opening. 
         [0004]    A sliding passenger door is a popular item on vans and minivans. Typically, both the left and right sides of a minivan may be equipped with sliding passenger doors for the second and third rows of seating. Conventionally, a fuel door covering a gas cap and gas filler neck is also located on one side of the vehicle, rearward of one of the sliding doors. Because of the desire to have a large ingress/egress opening when the sliding passenger door is open, the range of travel of the sliding door typically overlaps the area where a fuel door is installed. 
         [0005]    In order to prevent the sliding door from colliding with an open fuel door at a refueling stop, various protection systems have been put into practice. For example, a mechanical interlock using levers activated by the opening of the fuel door has been used to block operation of the sliding door until the fuel door is reclosed. It would be desirable to avoid the added costs of such a mechanical interlock system together with the manufacturing and resulting warranty costs associated with the mechanical system. 
         [0006]    It has also been suggested to include a position sensor in a fuel door that would disable operation of a power system for a powered sliding door when the fuel door is ajar. However, it would be desirable to avoid the necessity to make changes to the power sliding door system itself. Furthermore, prevention of powered sliding door operation without a mechanical interlock does not prevent accidental manual (i.e., unpowered) opening of the sliding door when the fuel door is open, especially from inside the passenger cabin where the open state of the fuel door is less apparent to the person opening the door. 
       SUMMARY OF THE INVENTION 
       [0007]    In one aspect of the invention, a transportation vehicle comprises a fuel door on a first side of the vehicle having an open position and a closed position. A sensor provides a fuel door ajar signal indicating whether the fuel door is in the open position or the closed position. A sliding door on the first side of the vehicle for passenger ingress and egress is movable between an open position and a closed position, wherein the open position of the sliding door interferes with the open position of the fuel door. The sliding door has an interior door handle and an exterior door handle, and there is at least one power lock switch for manually generating a lock signal or an unlock signal. A child lock switch manually generates a power child locking signal or a power child unlocking signal. An electronically-controlled latch system in the sliding door is responsive to 1) a power lock command for putting the latch system in an outside locked state for preventing the sliding door from being moved from the closed position using the exterior door handle, 2) a power unlock command for putting the latch system in an outside unlocked state for enabling the sliding door to be moved from the closed position using the exterior door handle, 3) a child lock command for putting the latch system in an inside locked state for preventing the sliding door from being moved from the closed position using the interior door handle, and 4) a child unlock command for putting the latch system in an inside unlocked state for enabling the sliding door to be moved from the closed position using the interior door handle. A lock controller is coupled to the sensor, the power lock switch, the child lock switch, and the latch system for responding to the fuel door moving to the open position by 1) preserving a current outside locked or unlocked state and a current inside locked or unlocked state, 2) initiating or maintaining the outside locked state and inside locked state, and 3) after the fuel door moving to the closed position, restoring or maintaining the preserved current outside locked or unlocked state and the preserved current inside locked or unlocked state. 
         [0008]    Many conventional power locking systems have been configured to latch and unlatch all passenger doors in concert. In the present invention, it is preferred (but not required) to configure the locking system to provide individual control of the locking of at least the sliding door (as is often done for the driver's door). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a block diagram showing a sliding door lock system with power locks and power child locks. 
           [0010]      FIG. 2  generally illustrates a powered sliding door on the same side of a vehicle as a refueling door. 
           [0011]      FIG. 3  is an electrical block diagram of one preferred embodiment of the invention. 
           [0012]      FIG. 4  is a flowchart of a first embodiment of a method of the present invention. 
           [0013]      FIG. 5  is a flowchart of a second embodiment of a method of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0014]    Referring now to  FIG. 1 , a typical power lock system will be described. A sliding door  10  has an outside handle  11  and an inside handle  12  for manually opening sliding door  10  when it is not locked by a latch system  13 . Latch system  13  is electronically controlled by a lock controller  14  which may reside in a smart junction box (SJB) of the vehicle electrical system. An SJB may integrate electronic controls of various vehicle systems and options. Alternatively, the lock control function could be integrated in any other body electronic module or in a stand alone module. 
         [0015]    A human-machine interface for controlling various door functions may include a button panel  15  (e.g., mounted to a driver's door) having a power lock toggle switch  16 , a child lock switch  17 , and a power sliding-door switch  18  which are all coupled to lock controller  14 . Power lock toggle switch  16  has an unlock legend  20  and a lock legend  21  that may be pressed in order to send a corresponding unlock or lock signal to lock controller  14 . Child lock switch  17  may preferably be a push-push switch associated with an indicator light  22  for showing whether the child lock feature is activated or deactivated. Power sliding-door switch  18  has a closed legend  23  and an open legend  24  that are pressed in order to generate signals for powered opening or closing of the sliding door. 
         [0016]    In a typical power lock system, the state of the power lock determines whether door  10  can be opened using outside handle  11 . More specifically, an unlock or lock signal from toggle switch  16  (or other control switches in the vehicle or on a wireless remote key fob), cause lock controller  14  to configure latch system  13  in either 1) an outside locked state for preventing the sliding door from being moved from the closed position using outside handle  11  or 2) an outside unlock state which enables the sliding door to be moved from the closed position using outside handle  11 . 
         [0017]    A power child lock function is comprised of an inside locked state or an inside unlocked state. To turn on the power child lock function, switch  17  is depressed, causing indicator  22  to illuminate and lock controller  14  to configure latch system  13  to the inside locked state which prevents the sliding door from being moved from the closed position using interior handle  12 . By pressing switch  17  again, the inside unlocked state is selected which enables the sliding door to be moved from the closed position using interior handle  12 . In a typical North American rear door system, the latch may be in a locked state but the latch can be mechanically unlocked from the inside of the rear door allowing the interior handle to unlatch and open the door from the inside. The child lock function works similar to the double lock system as generally used in Europe. A double lock state is set by sending a lock command to a latch that is already single locked. In a single locked state, the latch can be mechanically unlocked from the inside of the rear door allowing the inside handle to open the door. In the double locked state, the mechanical unlocking function of the inside handle is disabled just as it is in the child lock system employed in North America. As used herein, “child lock” refers to either system. 
         [0018]    In the present invention, lock controller  14  preferably includes a memory for storing the status of the power lock state and the child lock state. By preserving the states most recently chosen by the vehicle occupants, the present invention can alter the states temporarily and then restore them. 
         [0019]      FIG. 2  shows a vehicle  30  having a power-driven sliding door system that may be present in a vehicle using the invention. A sliding door  31  has a latch system  32 , an outside door handle  33 , and an inside door handle  34 . A power-drive system  35  is coupled with sliding door  31  for driving the sliding door  31  open and closed. A controller  36  is coupled to latch system  32  and power-driver  35  for coordinating system operation. 
         [0020]    Sliding door  31  can be opened in a direction shown by arrow  37  toward a refueling unit  40  mounted to the same side of vehicle  30 . A fuel door  41  has opened and closed positions for selectably covering a gas gap and filler neck (not shown). A fuel door lock  42  may be remotely controlled (e.g., by controller  36 ) to selectably lock and unlock fuel door  41  in its closed position. A door ajar sensor  43  provides a signal to controller  36  indicating whether fuel door  41  is in the open position or the closed position. When fuel door  41  is in an open position as shown in  FIG. 2 , sliding door  31  should not be capable of being opened to a position that collides with fuel door  41  either by powered driving by driver  35  or by manual opening using handles  33  or  34 . 
         [0021]      FIG. 3  shows the electrical components and signals of an embodiment of the invention in greater detail. A lock controller is incorporated within a body electronic module (BEM)  45  and provides lock/unlock commands and child lock on/off commands to a latch system  46  of the sliding door on the side with the fuel door. Latch system  46  may optionally provide a door ajar signal to lock controller  45  indicating when the sliding door is open. A sliding-door drive system  47  receives open and close commands from controller  45 . A fuel door sensor  48  provides a fuel door ajar signal to controller  45 , and a fuel door lock system  49  receives lock and unlock commands from controller  45 . 
         [0022]    A human-machine interface (HMI)  50  and/or a remote fob  51  provide operator signals to controller  45 , preferably including manual power lock and unlock commands and a power child lock setting. In addition, a manual fuel door lock control in HMI  50  or fob  51  can control the unlocking of fuel door power lock system  49  when the user desires to initiate the refueling of the vehicle. 
         [0023]    Controller  45  may also be coupled to an engine control unit (ECU)  52  which is connected to a vehicle start switch  53  for reasons discussed below. 
         [0024]    Using the electrical signals and subsystems shown in  FIG. 3 , the present invention provides a logic-based fuel door interlock system for preventing opening of the sliding door whenever it could collide with an open fuel door. The logic-based system avoids the added cost and disadvantages of a mechanical interlock. Furthermore, it prevents not only powered opening of the sliding door, but manual opening as well.  FIG. 4  shows a first embodiment of the present invention wherein the customer stops at a gas station to fuel their vehicle in step  60 . In step  61 , the customer manually opens the fuel door (after power unlocking the fuel door if so equipped). Upon opening, the fuel door activates a sensor switch that sends a corresponding signal to the electronic control module in step  62 . The electronic control module records the status (i.e., current lock states) of the power lock and the power child lock for the sliding door that is adjacent to the fuel door. 
         [0025]    In order to ensure that the sliding door cannot be opened, the electronic control module power child locks and power locks the sliding adjacent to the fuel door in step  64 . This prevents manual opening of the sliding door from either the inside or the outside of the vehicle and prevents powered opening from any door control switches (e.g., incorporated in the door handles or toggle switches within the vehicle). After the customer completes the fueling, the fuel door is closed in step  65 . In response to the closing of the fuel door, the electronic module changes the power child lock and power lock for the sliding door adjacent to the fuel door back to their original status in step  66 . 
         [0026]    A more detailed method is shown in  FIG. 5 . The customer stops at a gas station to fuel their vehicle in step  70 . A check is made in step  71  to determine whether the vehicle is stopped (e.g., by checking the transmission drive setting or checking if the speedometer indicates a speed below a predetermined value). If the vehicle is not stopped, then the fuel door is not allowed to unlock in step  72  and a return is made to step  71  to wait for the vehicle to stop. When the vehicle is stopped, the fuel door can be unlocked electronically in step  73  using a fob or other HMI control device in the vehicle. In step  74 , the customer manually opens the fuel door in order to remove the gas cap and begins refueling the vehicle. Upon opening of the fuel door, a fuel door sensor switch is activated and sends a signal to the electronic control module in step  75 . 
         [0027]    In this embodiment, a check is made in step  76  to determine whether the internal combustion engine is on (i.e., running). If so, then the electronic control module sends an engine shutoff command in step  77  to the engine control unit in order to shut-off the engine during refueling. After the engine is shut off or if the engine was not on, the method proceeds to step  78  wherein the electronic control module records the states of the power lock and child lock for the sliding door adjacent to the fuel door. Then the electronic control module power child locks and power locks the sliding door adjacent the fuel door in step  80 . 
         [0028]    The customer completes fueling and closes the fuel door in step  81 . A check is made in step  82  to determine whether the fuel door has closed. If not, the electronic module leaves the sliding door locked and prevents the engine from being started in step  83 . Then, a return is made to step  82  to wait for the customer to close the fuel door. During the time that the fuel door remains ajar, a warning light or a message on an HMI will preferably indicate to the driver that the fuel door is open and the engine disabled. After the fuel door is closed, the electronic control module changes the power child lock state and the power lock state of the sliding door adjacent to the fuel door back to the original states in step  84 . The electronic control module then allows the engine to be started in step  85  (e.g., by sending a signal to the engine control unit to no longer disable engine starting). 
         [0029]    In an alternative embodiment, when the vehicle includes a remote-controlled fuel door lock system it may be desirable to inhibit unlocking of the fuel door unless the sliding door is in its closed position so that it can be locked closed prior to allowing the fuel door to open. In yet another alternative, the act of causing the fuel door to unlock may trigger the interlock function, i.e., without relying on the fuel door ajar sensor to signal the opening of the fuel door before the sliding door is locked.