Proximity warning device for protection of a parked vehicle

Claim 1

A proximity warning device for protection of a parked vehicle comprising a sensor assembly, the sensor assembly comprising a relatively heavy body having a lighter elongated feeler element affixed to and projecting from the body, a housing for the sensor assembly, means for affixing the housing to a vehicle bumper, pivot means for pivotally supporting the sensor assembly in the housing for pivotal oscillation about a horizontal pivotal axis which is substantially perpendicular to the lengthwise dimension of the vehicle, the location of the pivotal axis being so selected that, when the housing is affixed to a bumper of a parked vehicle and the sensor assembly influenced only by gravity, the sensor assembly assumes a neutral orientation in which the feeler element is substantially vertical in the direction of its elongation regardless of whether the surface on which the vehicle is parked is horizontal or inclined in the lengthwise direction of the vehicle, ht e housing having an upper opening through which the feeler element upwardly projects with a substantial portion of the feeler element being above the housing and which permits the feeler element to oscillate in either direction from the neutral, substantially vertical orientation, the sensor assembly further comprising a liquid metal electrical switch integral with the rest of the sensor assembly, liquid metal switch comprising a channel which is downwardly inclined away from the vehicle in the direction of the lengthwise dimension of the vehicle when the sensor assembly is in said neutral orientation, a pair of electrical contact means received in the channel at respective locations spaced from each other in the lengthwise dimension of the channel, and a quantity of liquid metal received in the channel sufficient to contact only one of the electrical contact means when the sensor assembly is in said neutral orientation and sufficient to contact both of said electrical contact means when the feeler element is pushed toward the vehicle by external means sufficiently to substantially decrease the inclination of the channel, and respective electrically conductive wires electrically connected to each of the contact means and adapted to comprise an electrical circuit including alarm means responsive to closing of the liquid metal switch.