General Time Corporation

Donald R St Clair

Richard C St John

Gerald W Ogden

A sensing apparatus is responsive to the relative velocity of a vehicle and an impacted object in a crash environment to provide an output when a predetermined pressure is developed in a sensing chamber resulting in deployment of an air bag within the vehicle compartment. The purpose of the air bag is to restrain movement of the occupant relative to the vehicle in the event of a 'high speed' crash. The sensing apparatus utilizes in operation the characteristics of flow of a fluid through an orifice. The sensing apparatus includes a sealed chamber formed by a cylinder and an expandable reservoir for receiving the fluid and absorbing surges as the fluid flows through the orifice. A piston movable in the cylinder against a biasing force imparts movement to the fluid thereby to attain some velocity of flow. When the velocity shall equal a threshold velocity, the flow of fluid which theretofore was laminar, with little or no pressure differential across the orifice, becomes turbulent resulting in a build-up of pressure in the cylinder which rapidly increases as the velocity of the flow increases. A pressure transmitting member is reponsive to cylinder pressure thereby to provide the output when a predetermined pressure is reached.

Sensing apparatus with electrical actuation system

A sensing apparatus functions when the pressure in a sensing chamber attains a predetermined pressure level in response to a crash environment to actuate a pressure release valve and thereby provide an output resulting in the deployment of an air bag within the confines of a vehicle for restraining forward movement of an occupant. The particular level of pressure developed in the sensing chamber relates to the velocity of flow of a fluid under the control of a sensing means movable in the sensing chamber and whose movement, in turn, is responsive to the relative velocity of a vehicle and an impacted object. The operation of the impact sensing apparatus is the resultant of a true measure of the relative velocity of the vehicle and the impacted object; and upon attainment of a velocity of flow equal to or greater than a threshold velocity the pressure release valve will be actuated.

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Peru, IL, United States of America

Donald R St Clair