Abstract:
A method and system of controlling a movable body portion of a vehicle where the body portion is moved by a motor responding to a control input. Power is applied to the motor upon actuation of the control input and a timer is maintained concurrent with the application of power. Power is removed from the motor as a function of expiration of the timer or relinquishment of the control input. The timer provides a maximum amount of time that power may be applied to the motor, thereby preventing damage to the movable body portion in the event it becomes jammed while being moved by the motor.

Description:
PRIORITY CLAIM 
     This application claims the benefit of U.S. Provisional Application No. 60/286,937, filed on Apr. 27, 2001. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to control systems for automobile power convertible tops and power windows, and more particularly to a method of controlling an automobile power convertible top and power windows. 
     BACKGROUND 
     In the field of automotive design, convertible tops are used to provide automobiles that are capable of being driven with the top down or the top up. The drivers and passengers of convertible top automobiles often prefer to drive the vehicle with the top down when the weather outside is pleasant and place the top up when the weather turns foul or cold. Occupants of the vehicle also frequently put the automobile windows in the same position as the convertible top. That is, when the top is down, the occupants prefer to also have the windows down and vice-versa. 
     Typically, convertible tops are mechanically coupled to an electric motor that raises and lowers the convertible top in response to a command from an operator. The command is usually given through a power top switch conveniently located in the passenger compartment of the automobile, such as on the dash or center console. Similarly, typical power window arrangements are driven by electric motors that raise and lower the windows in response to commands from power window switches. 
     On vehicles having both a power convertible top and power windows, it is desirable to provide a control system that lowers the convertible top and windows with a single push of a button instead of the separate power top and window switches mentioned above. It is further desirable to provide a control system that protects the components of the convertible top structure and moving mechanism from damage due to excessive drive forces of the power top motor in the event the top structure becomes jammed while moving. Known control systems monitor the movement or position of the convertible top and turn off power to the electric motor when the top is completely raised, lowered, or becomes jammed. Such control systems require a feedback path that provides the control system with instantaneous information related to the positions of the structure members of the convertible top. These feedback paths require hardware that adds cost to the convertible top assembly, increases complexity in the assembly process, and requires maintenance. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method and apparatus for controlling the raising and lowering of an automobile body member, such as a convertible top or power window. 
     One aspect of the invention is to provide a convertible top control system that is integral to a power window control system, where the combined control system has the capability of raising and lowering the convertible top and power windows in response to a single operator input or switch actuation. 
     Another aspect of the invention is to provide a convertible top control system that raises and lowers the top in response to a single operator input, where the control system operates without need for a feedback path. 
     In accordance with these aspects, a method of controlling a movable body portion of a vehicle is provided where the body portion is moved by a motor that responds to a control input. The method applies power to the motor upon actuation of the control input and maintains a timer concurrent with the application of power. Power is removed from the motor upon the earliest occurrence of either the expiration of the timer or the relinquishment of the control input. The timer provides a maximum amount of time that power may be applied to the motor, thereby preventing damage to the convertible top in the event it becomes jammed while it is being moved by the motor. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram illustrating a convertible top control system; 
     FIG. 2 is a state diagram illustrating a method of controlling a convertible top and power windows, and; 
     FIG. 3 is an X-Y plot illustrating a predetermined time vs. battery voltage relationship. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to FIG. 1, a convertible top control system  10  is shown. The control system  10  is centered around a body controller module (BCM)  30  that executes a method  200  shown in FIG.  2  and explained later. The BCM monitors a power top switch assembly  20  that is used by an operator to indicate whether the top should be stopped, raised, lowered, or simultaneously lowered with the windows (express down). Switch assembly  20  is an example of such an assembly that is implemented in a resistive-multiplexed (R-mux) configuration. While the R-mux switch is discussed in more detail below, such a switch arrangement is not be construed as limiting. 
     R-mux switch assembly  20  is referenced to ground  28  and has an output connected to an analog-to-digital converter (A/D) pin  44  of the BCM  30 . The A/D pin  44  of the BCM  30  is pulled-up to a reference voltage (+V ref ) as is well known in the art. An operator presses switch  22  to indicate a top up state, and presses switch  24  to indicate a top-down state. Pressing switch  24  past a certain point causes switch  26  to close concurrently with switch  24 , thereby indicating a top and windows down state. All of the switches  22 ,  24 , and  26  are normally open. When neither switch  22  nor switch  24  is pressed, pin  44  is at a first voltage level. Pressing switch  22  causes a voltage level corresponding to a top-up command to appear at pin  44 . Pressing switch  24  causes a voltage level corresponding to a top-down command to appear at pin  44 , and pressing switch  24  even further, thereby causing switch  26  to close, effects yet another voltage level at pin  44  corresponding to the top and windows down state. 
     In accordance with the method  200 , the BCM  30  responds to the power top switch  20  by activating one or more of the top up relay  50 , the top down relay  40  and relays of the window relay box  60 . The output contacts of the top up relay  50  and top down relay  40  are electrically connected across a power top motor  70 . The output shaft of the power top motor  70  is mechanically connected to the convertible top (not shown) so that rotating the power top motor  70  in one direction causes the convertible top to move in a top up direction. Similarly, rotating the power top motor  70  in the opposite direction causes the convertible top to move in a top down direction and, finally, stopping the power top motor  70  causes the convertible top to stop moving. The power top motor  70  is preferably electrically protected by a top circuit breaker  120 . 
     As mentioned earlier, the BCM  30  is also electrically connected to a window relay box  60 . Actuating the window relay box  60  causes all window motors  80  to roll down the vehicle windows. The window relay box  60  contains a relay for each power window motor  80 . The relays inside of the window relay box  60  are electrically connected to the power window motors  80  in such a way that the relays are able to effect downward movement of the power windows by controlling electrical power to the power window motors  80 . Each power window motor  80  is preferably protected by a window circuit breaker  110  connected in series with the power window motor  80 . The system  10  also includes power window switches  90  electrically connected to the power window motors  80  to allow control of the power windows independent of the BCM  30  and window relay box  60 . Electrical power for the convertible top control system  10  is supplied by the vehicle electrical system, symbolized by the battery  100 . 
     FIG. 2 shows the control process executed by the BCM  30 . At power up, the method starts in state  210  and proceeds to state  220  where it reads the power top switch  20 . Upon detection that the power top switch  20  is in any of the top up, top down or top and window-down positions, the method proceeds to state  230  and determines whether the timer  32  has expired. The timer  32  keeps track of the amount of time that the power top motor  70  has been running in response to actuation of switch  20 . 
     Turning briefly to FIG. 3, a graph is shown indicating how the expiration time of the timer  32  is determined. The x-axis  190  of the graph represents the system voltage  100 , and the y-axis  180  represents expiration time. Curve  170  represents the maximum amount of time that it should take for the power top motor  70  to raise the convertible top at a given system voltage  100 . Similarly, curve  150  represents the maximum amount of time that it should take for the power top motor  70  to lower the convertible top at a given system voltage. Curve  160  represents the maximum amount of time that it should take for the power top motor  70  to lower the convertible top when the power windows motors  80  are simultaneously started with the power top motor  70  (express down). The method  200  allows the power top motor  70  to run for no longer than the predetermined amount of time from these curves to complete the desired operation. By limiting the amount of time the motor may run, the method  200  protects the components of the convertible top structure from being damaged by the drive forces of the power top motor  70  in the event the structure is jammed. The actual shape and relative positions of the curves  150 ,  160 , and  170  will vary depending on physical parameters such as the torque of the motors, the length and gauge of wires used in the system  10 , etc. In addition to choosing the time values to correspond to the maximum amount time it should take for the power top motor  70  to complete an operation, the time is also preferably less than the time it takes for the circuit breaker  120  to open when the convertible top is jammed. This allows an operator to clear the jammed top and resume operation of the system  10  without having to wait for the circuit breaker  120  to reset. Both requirements should be satisfied over a range of system voltages to produce a locus of points such as those shown in FIG.  3 . 
     Returning to state  230  in FIG. 2, if timer  32  has expired then the method proceeds to state  350  where the method shows that it has determined to turn off the power top motor  70 . The method then proceeds to state  340  where the BCM  30  actually turns off the power top motor  70  and resets the timer  32  before returning to state  220 . 
     Returning to state  230 , if the timer  32  has not expired, then the method proceeds to state  240  where it checks whether a predetermined condition has been met. In one aspect of the invention, the predetermined condition is that the vehicle must be travelling at a speed less than fifteen miles per hour. If the predetermined condition in state  240  is not satisfied then the method proceeds to state  350  and executes the aforementioned  110  sequence of states from  350  to  340  to  220 , thereby turning off the power top motor  70 , resetting the timer  32 , and returning to read the power top switch  20 . 
     If, instead, the predetermined condition in state  240  is satisfied, the method proceeds in accordance with the switch position determined in state  220 . More specifically, if the method determined the power top switch  20  is in the top up position then the method advances from state  240  to state  270 . In state  270  the method acknowledges the top up request before moving to state  320 . In state  320 , the method updates the timer  32  for a first duration of time  170  and activates the top-up  50  and top down  40  relays in such a manner as to cause power top motor  70  to effect raising of the convertible top. From state  320  the method returns to state  220  where the power top switch  20  is checked once again. 
     Returning to state  240 , if the method determined the power top switch  20  is in the top down position then the method advances from state  240  to state  280 . In state  280  the method acknowledges the top down request before moving to state  300 . In state  300  the method maintains a the timer  32  for a second duration of time  150  and activates the top-up  50  and top down  40  relays in such a manner as to cause power top motor  70  to effect lowering of the convertible top. From state  300  the method returns to state  220  where the power top switch  20  is checked once again. 
     Returning to state  240 , if the method determined the power top switch  20  is in the express down position, then the method advances from state  240  to state  250 . In state  250 , the method acknowledges the express down request before moving to state  260 . In state  260 , the method maintains the timer  32  for a third duration of time  160  and simultaneously activates the top-up relay  50 , top down relay  40 , and the window relay box  60 . This simultaneous activation causes the power top motor  70  to effect lowering of the convertible top concurrently with the lowering of the power windows by window motors  80 . 
     In each of states  300 ,  320 , and  260 , the method maintains the timer  32  by initiating the timer on the first entry into the state, and updating the timer value on each entry thereafter. The timer  32  is reset in state  340  when method turns off the power top motor  70 . 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.