Abstract:
An anti-pinch assembly is used for a closure panel supported by the motor vehicle. The closure panel is movable between an open position and a closed position. A controller is operably connected to the closure panel for controlling the operation of the closure panel. A position sensor is connected to the controller for indicating the position of the closure panel as the closure panel moves between the open and closed positions. A capacitive sensor is mounted on the frame of the vehicle and connected to the controller for providing an output signal to the controller indicative of the presence of a foreign object in the path of the closure panel. The controller varies the function of the capacitive sensor through a plurality of threshold levels as a function of the position of the closure panel as indicated by the position indicator. In a critical zone of travel, namely, travel of the closure panel nearing the closed position, the capacitive sensor can be utilized in either a contact mode or a non-contact mode or a combination of both.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to an anti-pinch system for a closure system associated with an aperture of a motor vehicle. More specifically, the invention relates to an anti-pinch system for an aperture of a motor vehicle wherein the anti-pinch system differentiates a number of zones.  
       DESCRIPTION OF THE RELATED ART  
       [0002]     Motor vehicles typically have anti-pinch systems associated with powered closure assemblies used to selectively open and close an aperture. By way of example only, an aperture of a motor vehicle is found within a door or side and the closure panel associated therewith is a window and its associated control mechanism. A non-exhaustive list of closure assemblies includes door windows, sliding doors, liftgates, deck-lids, sunroofs and the like.  
         [0003]     The anti-pinch systems associated with these closure assemblies typically sense the presence of a foreign object in the path of the closure panel by using characteristics such as motor current or a feedback device, such as a Hall effect sensor, position sensors, tachometer and the like. These feedback devices sense an abnormal characteristic in the parameter being sensed relative to the normal or unobstructed operating characteristic of the closure panel.  
         [0004]     U.S. Pat. No. 6,051,945, issued to Furukawa on Apr. 18, 2000, discloses an anti-pinch assembly for a closure panel. A processor controls a motor that moves the windowpane between its open and closed positions. A Hall effect sensing device is positioned such that it can sense the velocity of the output shaft of the motor. To measure velocity, the Hall effect sensors are disposed around the shaft of the motor. A magnet is secured to the shaft and provides the magnetic field required sensed by the Hall effect sensors. Once the velocity of the shaft is measured, acceleration is derived and the force is calculated using the mass of the windowpane. This system requires the use of multiple sensors and calculations to determine the presence of an object.  
         [0005]     Simple detection of obstructions based on motor speed or electrical current passing through the motor are inadequate due to the normally varying characteristics of these parameters through the full range of motion for the closure panel.  
       SUMMARY OF THE INVENTION  
       [0006]     The disadvantages of the prior art may be overcome by providing an anti-pinch assembly that prevents objects from getting caught by a closure panel of a motor vehicle by providing an anti-pinch system having multiple zones of varying sensitivity.  
         [0007]     According to one aspect of the invention, there is provided an anti-pinch assembly is used for a closure panel supported by the motor vehicle. The closure panel is movable between an open position and a closed position., A controller is operably connected to the closure panel for controlling the operation of the closure panel. A position sensor is connected to the controller for indicating the position of the closure panel as the closure panel moves between the open and closed positions. A capacitive sensor is mounted on the frame of the vehicle and connected to the controller for providing an output signal to the controller indicative of the presence of a foreign object in the path of the closure panel. The controller varies the function of the capacitive sensor through a plurality of threshold levels as a function of the position of the closure panel as indicated by the position indicator. In a critical zone of travel, namely, travel of the closure panel nearing the closed position, the capacitive sensor can be utilized in either a contact mode or a non-contact mode or a combination of both. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     Advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:  
         [0009]      FIG. 1  is a schematic of one embodiment of the invention;  
         [0010]      FIG. 2  is a side view of an aperture in a door of a motor vehicle incorporating one embodiment of the invention;  
         [0011]      FIG. 3  is a schematic view of the driving circuit for the invention of  FIG. 1 ;  
         [0012]      FIG. 4  is a cross section of a portion of an aperture and a window pane disposed adjacent a graphic representation of zones; and  
         [0013]      FIG. 5  is a cross section of graph of an aperture and a windowpane incorporating adhesive based sensor strips. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]     Referring to the Figures, an anti-pinch assembly is generally indicated at  10 . The anti-pinch assembly  10  is used in conjunction with a closure panel assembly. The closure panel assembly includes of a closure panel  12 , defining a leading edge  13 , and its operating system, discussed subsequently. The closure panel  12  travels along a path between open and closed positions. The anti-pinch assembly  10  prevents the closure panel  12  from pinching or crushing an obstruction or object (not shown) that may be extending through an aperture  14  of a motor vehicle  16  (both shown in  FIG. 2 ) when the closure panel  12  nears the closed position. It should be appreciated by those skilled in the art that the closure panel  12  may be any motorized or automated structure that moves between an open position and a closed position. By way of example, a non-exhaustive list of closure panels  12  include windowpanes, doors, liftgates, sunroofs and the like. Apertures include window frames, door openings, sunroof openings and the like. For purposes of simplicity, the remainder of this disclosure will focus on the windowpane and window frame combination.  
         [0015]     The anti-pinch assembly  10  includes a controller  18 . The controller  18  is electrically connected, directly or indirectly, to a power source  20 . A conductor  22  graphically represents this connection. The power source  20  is preferably the power source  20  for the motor vehicle  16 . The power source  20  may be a battery, a generator or any other electricity generating device or combination thereof.  
         [0016]     A motor  24  receives electricity through a conductor  26  that, directly or indirectly, operatively extends between the power source  20  and the motor  24 . The motor  24  rotates a shaft  28  operatively connected to the closure panel  12  in a conventional manner. The operative connection transforms the rotational energy into mechanical energy. More specifically, the electric output of the motor  24  into an opening and closing movement of the closure panel  12 . The motor  24  optionally may be provided with separate motor controller. Operation of the motor  24  is effected by the motor controller.  
         [0017]     A position sensor  30  is disposed adjacent the motor  24 . The position sensor  30  identifies the position of the shaft  28  of the motor  24  and generates a position signal. By identifying the position of the shaft  28  upon receipt of the position signal, the controller  18  determines with specificity the position of the leading edge  13  of the closure panel, i.e., the windowpane  12 . As the shaft  28  rotates, the position sensor  30  identifies where along the rotation the shaft  28  is as well as how many rotations the shaft  28  has executed. The degree of accuracy of the position sensor  30  is a variable that will depend on the specific design.  
         [0018]     In one embodiment, the position sensor  30  is a Hall effect sensor that utilizes a single magnet (not shown) that is secured to the shaft  28 . The magnet rotates with the shaft  28  and its magnetic field affects the position sensor  30  as it passes thereby.  
         [0019]     In an alternative embodiment, the position sensor is a Hall effect sensor that is secured to a portion of the mechanism (not shown) that moves the windowpane between the open and closed positions. The position sensor  30  could be secured to a drive screw, glass run channel or some other portion of the mechanism that moves proportionally to the windowpane or closure panel  12 .  
         [0020]     A capacitive sensor  32  is mounted relative to the window frame in a spaced relation and electrically connected to the controller  18 .  
         [0021]     The capacitive sensor  32  is capable of determining changes in magnetic fields in the surrounding space due to the introduction of an object that has a dielectric that is different than that of the surrounding space. The capacitive sensor  32  can be tuned to detect smaller changes in the surrounding space, i.e., when an object is extending through the window frame  40  but not touching the window frame  40 , referred to as a non-contact mode. The capacitive sensor  32  detects changes in the surrounding space defined by the aperture  14  by measuring the capacitance of the capacitive sensor  32 , discussed subsequently. Changes occur prior to the immediate closing of the closure panel  12  and when an object extends therethrough. An object extending through the aperture  14  will disrupt the dielectric fields being measured by the capacitive sensor  32  and the sensor  32  will responsively generate an output signal relative thereto.  
         [0022]     The capacitive sensor  32  may also be used in a second mode, i.e., a contact mode. In the contact mode, the sensitivity of the capacitive sensor  32  is reduced. Therefore, a change in the dielectric field surrounding the capacitive sensor  32  triggers the anti-pinch assembly  10  only when the capacitive sensor  32  is moved by the object when it actually contacts the sensor  32  or the sealing system  37  that houses the sensor  32 . The sensitivity of the sensor  32  is reduced so that the leading edge  13  of the closure panel  12  does not trigger the anti-pinch assembly  10 , which would result in the closure panel  12  failing to reach its closed position ever.  
         [0023]     Referring to  FIG. 4 , the capacitive sensor  32  is molded into a flexible, and/or low durometer compound, in a range of less than 40-50 Shore. The compound is flexible and configured as the sealing system  37  of the aperture  14 . Flexibility of the sealing system  37  can also be controlled by the cross-sectional configuration, including controlling thickness of the arm and walls supporting the capacitive sensor. In the embodiment shown in  FIG. 4 , the capacitive sensor  32  is molded directly into the sealing system  37 .  
         [0024]     Referring to  FIG. 5 , wherein like primed numerals represent similar elements in an alternative embodiment, the capacitive sensor  32 ′ may be added as an aftermarket item by using adhesive  39  to attach the capacitive sensor  32 ′ to the sealing system  37 ′.  
         [0025]     Referring to  FIG. 2 , a door  36  of a motor vehicle  16  is shown. The door  36  defines the aperture  14  (a window frame in this case) as an opening extending between a base  38  of the door  36  and around a window frame  40  having a forward boundary  42 , an upper boundary  44  and a rearward boundary  46 . The capacitive sensor  32  extends along the forward  42  and upper  44  boundaries. The capacitive sensor  32  is designed to measure the electromagnetic field directly therebelow within the aperture  14 .  
         [0026]     The capacitive sensor  32  is preferably a long conductor that extends out from and along a window frame  40  at a predetermined distance from the window frame  40 . The predetermined distance creates a specific capacitance for the capacitive sensor  32  because the capacitive sensor  32  uses the window frame  40  as ground. Any changes in the distance between the capacitive sensor  32  and the window frame  40  changes the capacitance in a manner far greater than when an object extends through the window frame  40  but does not touch the capacitive sensor  32 . This change in capacitance is monitored by the controller  18 . If an object, regardless of its dielectric constant, contacts the capacitive sensor  32  enough to flex it out of its position, the change is detected by the controller  18 , which will subsequently stop and/or reverse the closure of the window.  
         [0027]     The controller  18  includes a threshold generator  33  that generates a threshold value for the capacitive sensor  32 . This threshold determines in which zone the anti-pinch assembly  10  is operating. The threshold is a value of a dielectric that the capacitive sensor  32  can detect. The threshold generator  33  includes a pulse generator  34  and a threshold capacitor  35 . The threshold capacitor  35  is connected in parallel with the capacitive sensor  32  and is approximately 1000 times the capacitance of the capacitive sensor  32 . The pulse generator  34  generates a regular pulse train of less than 5 volts, preferably 3-5 volts at a frequency of about 12 Mhz (200-500 ns per pulse), which signal is applied to the capacitive sensor  32 . Since the capacitive sensor  32  is small in comparison with the threshold capacitor  35 , the capacitive sensor  32  will become fully charged quickly. Once charged, the pulse train is reflected back to the threshold capacitor  35  thereby charging it in a stepped manner, graphically represented at  39 , until the threshold capacitor  35  is fully charged. A counter  137  counts the number of pulses required to fully charge the threshold capacitor  35  and the count is placed in a floating memory. The capacitors  32 ,  35  are then discharged or reset and the process is re-started.  
         [0028]     The count can be averaged over time so that the effects of weather and other extrinsic conditions can be factored out. A comparator  45  compares the counts of successive counts.  
         [0029]     The determination of the presence of an obstacle is performed by monitoring the count. A measured signal is generated based on the monitored count. Any obstacle, whether it be a body part or otherwise, extending into the window aperture  14  or contacting the seal  44  will affect the dielectric constant of the field. The number of pulses required to fully charge the threshold capacitor  35  will increase should an object be present, resulting in an increased measured signal. If the change between a predetermined number of successive counts deviates or increases beyond a first predetermined threshold signal or count, the controller  18  determines that an object has extended through the window frame  40  or has moved the capacitive sensor  32  by touching or moving the sealing system  37 .  
         [0030]     When detection of an obstacle is made, the controller  18  then changes the motor signal being sent to the motor  24 . The new motor control signal directs the motor  24  to either stop the closure panel  12  from moving or to reverse the direction in which the shaft  28  is rotating, retracting the closure panel  12 . If the closure panel  12  is returned to its open position, the controller  18  normalizes the motor control signal and allows the motor  24  to operate according to normal operation. If the closure panel  12  remains in the same position, the anti-pinch assembly  10  will not allow the closure panel  12  to continue to its closed position until after the compare value is eliminated.  
         [0031]     As noted previously, the motor may be provided with a separate motor controller having a position sensor. Thus, the motor controller will provide a position signal to the controller  18  and the controller  18  will send a motor control signal back to the motor controller.  
         [0032]     Referring to  FIG. 4 , a graphic representation of multiple zones is generally shown at  56 . The graph  56  shows each zone  58 ,  60 ,  62  as a function of position or location of the leading edge  13  of the windowpane  12 . Each different zone  58 ,  60 ,  62  is contiguous with the next such that the leading edge  13  of the windowpane  12  can never in a position where controller  18  is not monitoring the capacitance of the capacitive sensor  32 . Each of the zones  59 ,  60 ,  62  is a graphic representation for each of a plurality of threshold values above which the count must reach before the anti-pinch assembly  10  stops or reverses the windowpane  12 .  
         [0033]     In the lower or primary zone  58 , the controller  18  increases the sensitivity of the capacitive sensor  32  to allow it to detect the presence of an object even when the object is low enough to avoid physically moving the capacitive sensor  32 .  
         [0034]     In the secondary zone  60 , usually about 4 mm separating the upper edge  13  of the windowpane  12  from the sensor  32 , the controller  18  decreases the sensitivity of the capacitive sensor  32 . The position sensor  30  generates the position signal and the controller  18  responsively determines when the windowpane  12  enters the secondary zone  60 .  
         [0035]     In this zone of operation, the ability to detect an object is reduced. In other words, the controller  18  applies a second predetermined threshold that has a magnitude and/or duration greater than the first predetermined threshold.  
         [0036]     The reduction in sensitivity allows the windowpane  12  to approach the capacitive sensor  32  without the controller  18  misidentifying the windowpane  12  as an object that might be pinched between the windowpane  12  and the window frame  40 . As may be appreciated by those skilled in the art, a decrease of sensitivity still allows the capacitive sensor  32  to detect an object contacting it. Therefore, should an object remain in the path of the windowpane  12  as the upper edge  13  approaches the sealing system  37 , the controller  18  will still be able to detect it and stop or retract the windowpane  12 .  
         [0037]     In the optional third or upper zone  62  of operation, the controller  18  deactivates the capacitive sensor  32 . This allows the windowpane  12  to enter the sealing system  37  to properly seal against thereto. The capacitive sensor  32  is deactivated because, depending on the sealing system  37 ; the capacitive sensor  32  may move upon entry. If it were still active, it would inhibit the closing of the window or aperture  14 . Upon the windowpane  12  being retracted, the controller  18  reverts to the reduced sensitivity mode (intermediate zone  60 ) and, subsequently, the higher sensitivity mode (lower zone  58 ). The anti-pinch assembly  10  will remain active until the windowpane  12  is returned to its closed position abutting the sealing system  37 .  
         [0038]     The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.