Vehicle impact sensor arrangement

A sensor arrangement for sensing a side impact on a motor vehicle which has a side having an outer skin and for activating a safety device within the vehicle, comprising:

• a sensor located between the outer skin of the side of the vehicle and an inner part of the vehicle which is relatively fixed in position, said sensor being adapted to initiate activation of the safety device only when the outer skin of the side of the vehicle moves at a speed greater than a predetermined speed relative to said fixed part of the vehicle, said sensor having:
• a first part in the form of a housing containing a pyrotechnic material, and
• a second part in the form of a stab,
• wherein one of said first and second parts is supported by an inner part of the vehicle which is relatively fixed in position and wherein the other of said first and second parts is adapted to be moved in response to movement of the outer skin of the side of the vehicle during an impact,
• wherein in an impact situation the second part in the form of a stab is moved into an engagement with the first part in the form of a housing containing a pyrotechnic material with a speed related to the speed of movement of the outer skin of the side of the vehicle, and
• wherein the pyrotechnic material ignites when the speed of movement of the outer skin of the side of the vehicle exceeds a predetermined level.