Patent US 4,166,641

An inflating device for safety air bag for an automotive vehicle is basically constructed with an air bag inflating implement, a first sensor which is installed in the neighborhood of the vehicle cabin and generates an actuating signal when a change in the running speed of the vehicle within a sampling time exceeds a predetermined value, a second sensor which is provided in a position forward of the first sensor and which detects the change in the vehicle speed at the initial stage of the collision, a third sensor which is provided within the vehicle cabin, the third sensor having no sampling time relative to a predetermined speed reduction value in the vehicle, and a memory device which is composed of an electronic circuit or mechano-electric components, in which construction the actuating signal is made to be applied to the air bag inflating implement when output signals are generated from the memory device and the first sensor simultaneously.