Movable or removable closures – Safety means responsive to obstruction to closure
Reexamination Certificate
1999-12-15
2004-08-10
Redman, Jerry (Department: 3634)
Movable or removable closures
Safety means responsive to obstruction to closure
Reexamination Certificate
active
06772559
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns a method called a sequential method for controlling a sliding moving panel driven by an electric motor, wherein the signal originating from an optical fibre pressure sensor is exploited in a sequential manner to stop and reverse the operating direction of the driving motor in the event of a variation in said signal, and wherein the frequency measurement of the pulses generated by an encoding device is exploited to perform pre-detection of an obstacle and to determine the end of travel positions of the moving panel.
The invention also concerns a safety device for such a moving panel including means for detecting the presence of a foreign body braking said moving panel's movement and preventing it from closing completely.
The invention also concerns an optical fibre force sensor able to be used in particular in safety devices of the aforementioned type.
Finally, the object of the invention is to provide a method for calibrating the aforementioned direct and indirect detection means which allows the reliability of the operation of the sensor to be increased.
Automobile vehicles are increasingly fitted with electric windows, i.e. systems wherein the windows are driven so as to slide in the opening direction or the closing direction by an electric motor whose operation is controlled by the driver of the vehicle by means of a manual switch. Such systems have allowed substantial progress to be made as regards automobile safety, insofar as the driver can easily open or close the windows while continuing to pay attention to traffic conditions and to driving the vehicle. These systems have, however, significant problems as to reliability which are often linked to the appearance of current peaks when the motor driving the window is stopped too abruptly. It is known that any obstacle blocking the movement of the window generates current peaks in the motor which are generally damaging, particularly for certain components, such as the control relays or the switching transistors. Such peaks can appear, for example, when the driver continues to activate the switch which controls the operation of the driving motor when the window has already reached the closed position in which it is pressed against the door frame. Current peaks can also appear when a foreign body, for example an arm, is resting on the edge of the window and prevents the latter from moving upwards.
In order to overcome the aforementioned difficulties, a known solution consists in measuring the maximum level of the supply current provided to the driving motor, and blocking said current above a predetermined threshold. This measurement is generally performed across the terminals of a switching transistor whose resistance varies from one component to another and remains dependent upon the temperature. Other methods use precision resistors (current measurements) or Hall effect sensors (magnetic field measurements), but the cost price of such components is high.
Another control method, which is less expensive and more efficient, consists in detecting the pulses caused by the switching of the driving motor brushes. These pulses are superposed with the direct consumption current of the motor, and their frequency is proportional to the speed of the rotor. A technique of this type is described in U.S. Pat. No. 4,870,333 in the name of the Sidosha Denki Kogyo company which proposes a method for controlling electric windows for automobile vehicles wherein the number of pulses generated by the operation of the electric motor driving the window is stored in a counter. When the number of pulses stored in the counter reaches a maximum predetermined value, the control device which operates the system concludes that the window has reached the fully open position and causes the driving motor to stop. Conversely, when the window moves up, the number of pulses stored in the counter is reduced by one unit per revolution of the driving motor. When this number becomes equal to zero, the system concludes that the window has reached the closed position in which it presses against the door frame, and again stops the driving motor.
The main drawback of the above system is that the speed at which the window rises is not constant and depends on numerous parameters such as the drive torque of the motor, the friction between the window and the door frame, the speed and trajectory of the vehicle, etc. Consequently, the position of the window cannot be calculated with sufficient accuracy for the moment at which the window is completely closed to be determined exactly. With such a method, one can at most determine an end of travel zone in which one knows that the window is close to the door frame. The driving motor can, consequently, be stopped on the command of the control device before the window is completely closed. Conversely, the window can continue to be supplied with current when the window is already completely closed, which generates current peaks which are damaging to the motor and the electronic control circuit. On the other hand, nothing in the Sidosha patent is provided for detecting, prior to pinching, an overload which would form an obstacle to the progress of window. Finally, nothing is provided for detecting the presence of a foreign body such as a child's hand, the thickness of which is equal to or less than the end of travel zone. Thus, during the automatic closing of moving panels, such as, in particular, an automobile vehicle window, one has to try to assure safety by preventing a foreign body such as, for example, an arm or a hand, being caught between said window and the door frame against which it has to be pressed. For this purpose, in the event that something is caught, a safety device stops the driving or reverses the direction of movement of the window. Among known safety devices, one solution consists in incorporating an electromagnetic wave guide, for example an optical fibre, inside the sealing gasket into which the window is guided. An emitter, for example a laser diode, injects a light signal at the end of the fibre. This signal propagates up to a receiver, for example a photodiode, placed at the other end of the fibre. In the event of an incident, the foreign body is driven by the window as it moves upwards towards the sealing gasket and exerts pressure on the optical fibre. By the effect of the pressure, the optical fibre is deformed, which causes a local modification in its radius of curvature. This modification in the fibre's radius of curvature causes significant losses, and consequently a drop in the amplitude of the optical signal picked up by the receiver. There results a drop in the amplitude of the electric signal transmitted by the receiver to a control circuit, which, in response to this drop, produces a stop or direction reversal signal for the motor driving the window.
A safety device associated with the sliding window of the door of an automobile vehicle is known from German Patent No. DE 44 16 803. This device includes a magnet arranged on the shaft of the electric motor driving the window with which is associated a Hall effect sensor. As a function of the signals transmitted by the Hall effect sensor, a microprocessor can determine that the window has reached its completely closed position. The microprocessor can also detect a reduction in the speed at which the window moves upwards due to the effect of the presence of a foreign body, and can command the reversal of the direction of movement of said window to avoid anything being caught therein. In addition to this indirect detection device, the safety device includes a direct detection device including a pressure sensor arranged in the door frame.
The main drawback of the above safety device lies in the fact that the indirect detection means continue to be used as obstacle detection means even when the window comes in proximity to its completely closed position. It has already been stated that the speed at which the window moves upwards is not constant and that it depends on numerous p
Bouamra Mohamed
Iriondo Jésus
Vicandi Javier
Zaldua Jésus
Redman Jerry
Sughrue & Mion, PLLC
Talltec Technologies Holdings S.A.
LandOfFree
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