1. Field of the Invention
The present invention relates to a position detection and anti-pinch system for a power window of a vehicle and more particularly to a position detection and anti-pinch system and method for detecting the position of a window in a vehicle door assembly.
2. Background Art
Door assemblies for automotive vehicles generally include a metal door frame attached to the body of a vehicle. The door frame generally includes inner and outer door frame panels joined about a common edge and a door sill running along top edge of the door to define a window frame. The window frame includes an opening or channel extending through the door frame to receive a window pane. A reinforcement panel may be attached to the inner door panel to provide additional structural support for the door frame and to receive various hardware components. Hardware components such as a handle assembly, window regulator and motor assembly, and electrical components such as interior lights and speakers, are secured to the reinforcement panel concurrently with assembly of the vehicle door.
Certain vehicle door assemblies include automatic vehicle window adjustment having a “one-touch up” feature. The “one-touch up” feature allows a passenger to raise the window pane with a single touch of a control button on the vehicle door. When actuated, the switch activates a motor assembly operatively connected to a window regulator, causing the window regulator to move the window pane upward toward the top of the window frame to a fully closed position without additional operator intervention. Of particular concern with such “one-touch” systems is that the passenger may not be able to stop the upward travel of the window pane if an object or an appendage of a person becomes pinched or trapped between the moving window and the window frame, which may lead to significant bodily harm.
Several types of obstruction detection systems have been proposed for vehicle door assemblies. One known obstruction detection system includes a control module which senses current spikes in the window drive motor or pressure on the window which would indicate an obstruction being pinched between the upward moving window and the window frame. The obstruction detection system stops and/or reverses the motor upon sensing the current spike or increased pressure while raising the motor. The problem with this design is that an object must be trapped or pinched with sufficient force for the system to sense the need to reverse the motor and lower the window, causing undesirable injury to an occupant prior to the lowering of the window. Further, the sensor is mounted adjacent the motor rather than the window pane, which does not provide an accurate measurement if an object becomes trapped between the window and window pane.
Another known obstruction detection or anti-pinch system includes a window seal with a gasket having varying resistivity based upon its level of compression. For example, if an obstruction is pinched between the window and the window frame, the gasket is locally compressed, which alters the resistivity of the gasket. A low current is applied through the gasket, and the variation in resistivity may be sensed to determine the existence of the obstruction, at which point upward movement of the window would be stopped. The system is not particularly desirable because the resistive gasket and associated electronics may be costly and injury may still occur prior to the lowering of the window.
Generally, it is known in window control designs to determine the velocity of a power window via pulses from the rotation of a motor's shaft. These pulses are generated by Hall sensors (magnetic sensing), CPD (commutator pulse detection) or switches that provide an open or closed circuit as the motor spins. To coordinate a system to detect information about a moving power windowpane, a supplier must change the system that they are designing to accept these pulses. Control algorithms must then be used to determine the velocity and position of the windowpane based on the received the pulse information. This task is especially critical when considering safety standards like FMVSS 118, where an obstacle must be detected during an auto-up function before a predetermined force is exerted on the window as a result of an obstruction in the path of the power window.
With such stringent guidelines, the control system in such motor pulse generating arrangements must “learn” the characteristics of not only the motor, but the regulator, grease and all of the mechanical linkages between the motor and the window. The system must also be able to accommodate temperature variation and different road conditions into the control process. All of these factors must be considered to provide flawless auto-up operations.
Accordingly, it is desirable to provide an improved window position detection and anti-pinch system for an automatic power window of a vehicle. It is also desirable to provide a window position detection system incorporating an anti-pinch detection system which prevents an obstruction from becoming trapped or lodged between a window and a window frame of the vehicle door.