Pressure drop signal generating valve cap for pneumatic tires

Claim 1

A pressure drop signal generating valve cap for a pneumatic tire equipped with a tire valve having a valve tube, the valve cap comprising: a housing to be screwed onto said valve tube and including a pressure chamber and a reference chamber, said pressure chamber being admittable with a tire pressure to be controlled and said reference chamber being admittable with a given desired pressure; a diaphragm separating said two chambers and adapted to become deflected into said pressure chamber whenever the tire pressure to be controlled is lower than the desired pressure; an actuator means for opening the tire valve whenever the valve cap is screwed onto the valve tube; a transmitter means including electric, electronic and circuitry components thereof, which--when activated--generates at least one signal frequency being wireless transmittable to a receiver means arranged adjoining to said pneumatic tire, and comprising a sequence control which terminates said signal transmission after a short duration thereof and resets said transmitter means in a stand-by state to become activated again; a circuit board arranged within said housing and supporting said electric, electronic and circuitry components of the transmitter means; a power supply means arranged at or within said housing; and a mechanically operated switching means comprising a fixedly arranged conductor section and a movably arranged contact piece, both being operatively connected with a circuitry unit of the transmitter means, wherein said conductor section is arranged in a short distance to a rest position of the diaphragm in such a manner that a diaphragm deflection causes an electrically conductive connection between said conductor section and said contact piece.