Signal device for pneumatic tire

Claim 1

A combined cap and signal device for a pneumatic tire comprising: a cap-like casing having a closed end and an open threaded end a hollow adaptor having a first threaded end engaging with said open threaded end of said casing and a second threaded end to be connected to an inflating valve of the tire, said hollow adaptor having a wall which has a stepped portion defining an annular shoulder and an internal thread formation adjacent to said annular shoulder, said hollow adaptor further having a transverse partition member formed near said second threaded end, said transverse partition member having a central finger piece axially projecting therefrom to open the inflating valve of the tire and air inlet openings, a disc member made of a resilient material and having a peripheral flange secured to said annular shoulder, said disc member cooperating with said partition member to confine an air chamber communicating with said air inlet openings, said disc member having a projection axially extending in a direction opposite to said finger piece; a hollow screw member for securing said peripheral flange of said disc member to said annular shoulder, said hollow screw member being inserted in said adaptor to clamp said peripheral flange of said disc member against said annular shoulder and having an external thread engaging with said internal thread formation of said hollow adaptor, said hollow screw member having an annular end serving as an electrical contact surface; an electric alarming unit mounted in said cap-like casing, said alarming unit including a sound producing circuit, and a cell means electrically connected to said sound producing circuit, first means for electrically connecting said sound producing circuit to said electrical contact surface of said hollow screw member; second means for electrically connecting said cell means to said electrical contact surface of said hollow screw member, said means including a conductive plate member to contact said electrical contact surface, and a coil spring having one end connected to said conductive plate member and the other end electrically connected to said cell means; said projection of said disc member pushing said conductive plate to move away from said hollow screw member when the tire is not deflated, said spring urging said conductive plate to be in contact with said hollow screw member when the tire is deflated to a predetermined reduced pressure.