Compact crash sensing switch with air ducts and diagnostic system
First Claim
1. In an occupant protection system of the type comprising a first crash sensor for sensing a vehicular crash and thereupon completing an electrical firing circuit;
- the improvement comprising,said first crash sensor incorporating resistance sensing means for determining if the resistance of said electrical firing circuit is between predetermined limits.
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Accused Products
Abstract
A crash sensor for automobiles of the type including a ball moving against viscous damping in a closed tube has a much smaller hall than known designs and a power transistor to switch power in the firing circuit. A resistance sensing circuit enables the crash sensor to monitor the firing circuit and indicate a change in the resistance of the fining circuit. In two embodiments simple message patterns allow communication of diagnostic information through existing wiring. A latching circuit maintains the switch in its closed state after initial closing. The small size of the ball enables use of a plastic or aluminum tube. The tube may have fluted walls that form air ducts that viscously conduct much of the air displaced when the ball moves. Routing most of the air through the ducts eliminates the uncertainty in the viscous resistance resulting when all of the air flows between the ball and the inner diameter of the tube. The movable element may be a sensing mass having a nonspherical shape. Compensation for the variation of air viscosity with temperature may be obtained by varying the normal resting position of the sensing mass as a function of temperature or by varying the size of the air ducts. The small sensing mass and electronic components allow simple contacts. The combination of these elements provides a crash sensing and diagnostic system costing much less than known systems.
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Citations
16 Claims
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1. In an occupant protection system of the type comprising a first crash sensor for sensing a vehicular crash and thereupon completing an electrical firing circuit;
- the improvement comprising,
said first crash sensor incorporating resistance sensing means for determining if the resistance of said electrical firing circuit is between predetermined limits. - View Dependent Claims (2, 3, 4, 5, 6)
- the improvement comprising,
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7. In an occupant protection system of the type including a first crash sensing means adapted for closing a first switch upon sensing a crash and also including a second crash sensing means adapted for closing a second switch upon sensing a crash for initiating deployment of occupant protection equipment, said first and said second switches being connected in series so that both of said switches must be closed to initiate deployment of said occupant protection equipment, the improvement comprising:
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electrical resistance means connected in parallel with one of said switches and adapted to cease conducting electricity when voltage is applied to it for more than a predetermined time period, and means responsive to a malfunction in said system for applying said voltage to said electrical resistance means for more than said predetermined time period. - View Dependent Claims (8)
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9. An occupant protection system for a vehicle of the type comprising a first crash sensor for sensing a crash of said vehicle, said first crash sensor being connected with other elements of said occupant protection system by exactly two electrical conductors wherein:
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said first crash sensor includes means for detecting a fault in said occupant protection system, and means for transmitting information about said fault to another element of said occupant protection system by broadcasting said information on one of said two electrical conductors. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification