Calibratable crash sensor
First Claim
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1. A deceleration sensor comprising:
- a piston seat;
a piston having a front side, a rear side, a rest position in engagement with said piston seat, and an activated position spaced a distance from said rest position;
means for supporting said piston for inertial movement from said rest position to said activated position in response to deceleration;
means for sensing movement of said piston from said rest position to said activated position to indicate a predetermined amount of deceleration over a time interval;
biasing means for exerting a retaining force to releasably hold said piston in said rest position;
means for containing a damping fluid which exerts an increasing pressure on said front side of said piston and a decreasing pressure on said rear side in response to said inertial movement of said piston, and for defining a control volume of said damping fluid at said rear side of said piston; and
means for varying said control volume while said retaining force is maintained at a constant level.
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Abstract
A vehicle crash sensor which operates to activate a passenger safety device such as an airbag inflator is calibratable to provide a desired sensitivity of the sensor to decelerating crash pulses of varying magnitude and duration. The sensor includes an adjustable member which varies the volume of a controlled quantity of damping fluid simultaneously with variations of the piston travel distance.
27 Citations
30 Claims
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1. A deceleration sensor comprising:
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a piston seat; a piston having a front side, a rear side, a rest position in engagement with said piston seat, and an activated position spaced a distance from said rest position; means for supporting said piston for inertial movement from said rest position to said activated position in response to deceleration; means for sensing movement of said piston from said rest position to said activated position to indicate a predetermined amount of deceleration over a time interval; biasing means for exerting a retaining force to releasably hold said piston in said rest position; means for containing a damping fluid which exerts an increasing pressure on said front side of said piston and a decreasing pressure on said rear side in response to said inertial movement of said piston, and for defining a control volume of said damping fluid at said rear side of said piston; and means for varying said control volume while said retaining force is maintained at a constant level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of calibrating a deceleration sensor comprising a piston having a front side, a rear side, a rest position, and an activated position, means for biasing said piston into said rest position, means for supporting said piston for inertial movement from said rest position to said activated position in response to deceleration, a fluid for damping said movement of said piston by exerting an increasing pressure at said front side of said piston and a decreasing pressure at said rear side in response to said movement, and means for sensing and indicating movement of said piston from said rest position to said activated position in response to a deceleration pulse of sufficient magnitude and duration to move said piston out of said rest position against a threshold level of said bias and between said positions against said bias and said damping, said method comprising the steps of:
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(a) providing a control space for containing a quantity of said fluid at said rear side of said piston; (b) varying the volume of said control space to vary the volume of said fluid at said rear side of said piston to cause a variation in the rate at which said pressure at said rear side of said piston decreases upon said inertial movement of said piston; and (c) retaining said threshold level of said bias constant while varying said volume. - View Dependent Claims (11)
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12. A deceleration sensor comprising:
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a piston seat; a piston having a front side, a rear side, a rest position in engagement with said piston seat, and an activated position a predetermined distance from said rest position; means for supporting said piston for inertial movement from said rest position to activated position in response to deceleration; biasing means for exerting a retaining force to releasably hold said piston in said rest position; means for sensing movement of said piston from said rest position to said activated position to indicate a predetermined amount of deceleration over a time interval; means for containing a damping fluid which damps said inertial movement of said piston from said rest position to said activated position, and for defining a control space containing a volume of said damping fluid at said rear side of said piston when said piston is in aid rest position, the pressure in which decreases as said piston moves from said rest position toward said activated position; and
,means for adjusting said volume to vary the rate at which said pressure decreases per increment of movement of said piston while maintaining said retaining force at a constant level. - View Dependent Claims (13, 14, 15, 16)
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17. A deceleration sensor for activating a vehicle occupant safety apparatus in response to deceleration of a vehicle, the safety apparatus including an electrical current path, said deceleration sensor comprising:
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a piston seat; a piston having a front side, a rear side, a rest position in engagement with said piston seat, and an activated position spaced a distance from said rear position; means for supporting said piston for inertial movement from said rest position to said activated position in response to a predetermined amount of deceleration of the vehicle; biasing means for exerting a retaining force to releasably hold said piston in said rest position; means for sensing movement of said piston into said activated position and for enabling electric current to flow along the current path int he safety apparatus to activate the safety apparatus in response to movement of said piston into said activated position; means for containing a damping fluid for exerting a damping force resisting movement of said piston from said rest position to said activated position; and means for adjusting said damping force while said retaining force is maintained at a constant level. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification