Communications: electrical – Land vehicle alarms or indicators – Of collision or contact with external object
Reexamination Certificate
1999-05-10
2001-05-22
Tong, Nina (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
Of collision or contact with external object
C340S903000, C307S010100, C701S045000, C280S735000, C180S282000
Reexamination Certificate
active
06236308
ABSTRACT:
TECHNICAL FIELD
This invention relates to automotive passenger restraint systems, and more particularly to a control method that differentiates deployment events from non-deployment events.
BACKGROUND OF THE INVENTION
In general, automotive passenger restraint systems perform a number of functions including acceleration sensing, signal processing and analysis, and deployment of one or more restraint devices such as frontal or side air bags and seat belt pretensioners in response to a sensed crash event. Typically, the acceleration signal is monitored to detect a potential crash event, and then filtered or integrated over the course of the crash event to produce a velocity change or &Dgr;V signal. If the &Dgr;V signal exceeds a threshold, the crash event is determined to be sufficiently severe to warrant deployment of restraints. The threshold is typically time-dependent, and is calibrated based on data logged for different types of crash events, as well as data logged during rough road driving.
There are a number of drawbacks with the above-described approach. For example, it is often difficult to reliably synchronize the time progression of the crash (that is, the event clock or timer) with the actual crash event. This makes it difficult to distinguish between deployment events and non-deployment events, particularly in the first portion of the sensed event. Additionally, it is difficult to deploy restraints quickly enough in certain high speed crash events and localized impacts if the deployment decision is based solely on a detected change in velocity (&Dgr;V) as described above.
SUMMARY OF THE INVENTION
The present invention is directed to an improved deployment method for a vehicular supplemental restraint system having an acceleration sensor and a restraint device to be deployed for occupant protection in a crash event, where the deployment is initiated when a filtered version of the acceleration signal exceeds a deployment threshold that is periodically adjusted based on one or more secondary measures of crash severity, including a measure of vehicle speed at the onset of the crash event, and the level of event progression. Preferably, the level of event progression is determined by deriving a &Dgr;V signal biased toward zero, and comparing such signal to a set of predefined event progression thresholds.
In a preferred embodiment, the deployment threshold is set to a relatively high default level during periods of inactivity to provide good immunity to rough road impacts, while providing timely deployment for high speed crash events, and is periodically adjusted from the default level in the course of a sensed event. At each level or stage of the event progression, the deployment threshold is adjusted within predefined boundaries based on the measure of vehicle speed. In a first embodiment, the vehicle speed measurement pertains to the ground or absolute speed of the vehicle at the onset of the crash event; in a second embodiment, the vehicle speed measure pertains to the vehicle speed relative to a detected obstacle at the onset of the crash event.
REFERENCES:
patent: 5969599 (1999-10-01), Wessels et al.
Delphi Technologies Inc.
Funke Jimmy L.
Tong Nina
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