Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2001-02-27
2004-04-20
Luu, Thanh X. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C033S366230, C073S514190
Reexamination Certificate
active
06723979
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to roll (tilt) sensors and, more particularly, to an electromechanical roll arming sensor, particularly for use in arming devices for deployment of occupant protection devices upon detecting a potential rollover condition for a vehicle.
BACKGROUND OF THE INVENTION
Automotive vehicles are increasingly employing safety-related devices that deploy in the event that the vehicle experiences a rollover so as to provide added protection to the occupants of the vehicle. For example, upon detecting an anticipated vehicle rollover condition, a pop-up roll bar can be deployed such that, when activated, the roll bar further extends vertically outward to increase the height of support provided by the roll bar during a rollover event. Other controllable features may include actuating deployment of one or more airbags, such as front and side airbags, or actuating pretensioners to pretension restraining devices, such as seatbelts or safety harnesses, to prevent occupants of the vehicle from ejecting from the vehicle or colliding with the roof of the vehicle during a rollover event.
In the past, mechanical-based rollover sensors have been employed in automotive vehicles to measure the angular roll position of the vehicle from which a rollover condition can be determined. The mechanical sensors have included the use of a pendulum normally suspended vertically downward due to the Earth's gravitational force. Many mechanical automotive sensing devices are employed simply to monitor the angular position of the vehicle relative to a level ground horizontal orientation. As a consequence, the basic automotive vehicle rollover sensors have generally been susceptible to error when the vehicle travels around a corner or becomes airborne, in which case the Earth's gravitational force, which the sensor relies upon, may be overcome by other forces.
More sophisticated rollover sensing approaches have been considered which employ a plurality of sensors, a microprocessor for processing the sensed signals according to one or more software algorithms, and communication lines between the microprocessor and deployable devices. Such approaches require as many as six sensors, including three accelerometers and three angular rate sensors. The three accelerometers generally provide lateral, longitudinal, and vertical acceleration measurements of the vehicle. The three angular rate sensors, also referred to as gyros, measure pitch rate, roll rate, and yaw rate.
In commercial applications, many sophisticated rollover sensing approaches also employ a safing device, such as an arming sensor, to provide an independent verification of an actual rollover event and prevent inadvertent deployment of devices due to a possible failure of any of the sensors, the microprocessor, the software algorithms, and the signal communication lines. Conventional arming sensors have included the use of a Schmidt tilt switch which employs a tilting cone vertically disposed relative to the vehicle and aligned with the vertical gravity vector. An optical light beam is generated by an infrared diode. An optical path formed within the tilting cone is aligned to allow the light beam to travel from the infrared diode to a phototransistor during normal vehicle travel. Upon experiencing a sufficient roll angle or roll rate, the tilting cone tilts relative to the vertical orientation to prevent the light beam from passing to the phototransistor, thereby generating an arming signal for use in allowing a rollover deployment to occur.
While the use of a Schmidt tilt switch as an arming sensor has served satisfactorily for some applications, this type of conventional arming sensor is susceptible to some false arming conditions. For example, the conventional tilt switch is generally responsive to non-roll forces, such as those caused by vehicle braking (deceleration) and those experienced during a free-fall of the vehicle, which may occur during normal routine driving with little or no possibility of a rollover. In addition, some conventional arming sensors are generally expensive.
Accordingly, it is therefore desirable to provide for an affordable and accurate roll arming sensor for arming devices for deployment upon detecting a rollover event for a vehicle. More particularly, it is desirable to provide for a roll arming sensor that is affordable and accurate for detecting when the vehicle experiences a minimum roll angle that is sufficient to serve as an arming signal.
SUMMARY OF THE INVENTION
In accordance with the teachings of the present invention, a roll arming sensor is provided. The roll arming sensor includes a housing defining a first cavity, a source for generating a signal beam, such as a light emitting diode, and a receiver for detecting the signal beam. A first cylindrical member is disposed substantially horizontal within the first cavity and between the source and receiver. When used on a vehicle, the first cylindrical member is oriented substantially parallel to the longitudinal axis of the vehicle and is configured to roll substantially perpendicular to the longitudinal axis of the vehicle upon experiencing a sufficient roll angle. The first cylindrical member has a window extending therethrough and is located in a first position during a non-armed condition such that the signal beam passes through the window. The first cylindrical member is movable to a second position during an armed condition. In the second position, the window is positioned to prevent the signal beam from reaching the receiver, thereby generating an arming signal at an output.
Accordingly, the present invention advantageously provides for a cost effective roll arming sensor that achieves enhanced reliability. The roll arming sensor is particularly useful for arming one or more devices for deployment by a rollover detection apparatus for use in a vehicle.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.
REFERENCES:
patent: 5013909 (1991-05-01), Sondergeld et al.
patent: 6202488 (2001-03-01), Cash
“SCHMIDT® Tilting Sensor BS 13.011” SCHMIDT Feintechnik GmbH, Germany, 8 pages, no date.
Chmielewski Stefan V.
Delphi Technologies Inc
Luu Thanh X.
Sigler Robert M.
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