Sensing apparatus with electrical actuation system

Claim 1

Impact sensing apparatus for use in activating inflation apparatus for deploying an air bag upon an impact of a vehicle with an object when the relative velocity of the vehicle and the impacted object is at least equal to a threshold velocity comprising housing means, means for mounting said housing means on the vehicle for conjoint movement therewith, said housing means defining a fluid cavity for confining a fluid medium, said cavity having a pair of chambers, an orifice between and in fluid communication with each chamber, sensing means within one of said chambers and displaceable from a first position in response to forces of impact of said vehicle and said impacted object for impelling said fluid medium from said one chamber, through said orifice into said other chamber which accumulates surges of said fluid medium whenever said sensing means shall be displaced from said first position, said orifice being shaped and sized for creating at least a predetermined pressure level within said one chamber at said threshold velocity, switch means for activating said inflation apparatus including a movable and stationary contact member, switch operator means responsive to said predetermined pressure level to move said movable contact member from a normally open to a closed contact position, said switch operator means including force transmitting means, an opening in said housing means into said cavity, and said force transmitting means in a first position sealing said opening, an actuating member contacting both said force transmitting means and said movable contact member and movable conjointly with said force transmitting means from said first position for closing said switch means to complete a circuit to enable activation of said inflation apparatus, bias means urging both said actuating member and force transmitting means to said first position, said actuating member and force transmitting means movable from said first position in response to attainment of said predetermined pressure level, locking means including a locking arm and spring means connected to said locking arm for biasing said arm from a first position toward said movable contact member, and means supporting said locking means in said housing means adjacent said switch means so that said locking arm is biased into frictional engagement with said movable contact member when said switch means is open to substantially eliminate the possibility of movement of said movable contact member except under control of said switch operator means.