Patent ID: RE41058

Claim:
A device capable of signalling the inflating condition of a tire when screwed onto a jointing tube ( 5 ) of an inflating valve ( 6 ) that has a self-closing valve core ( 7 ) stressed for closure by a valve spring ( 8 ), the claimed device comprising: a. an external envelope ( 1 ) b. a threaded body ( 4 ) slidably mounted at least partially within and rotating together with the external envelope ( 1 ), which threaded body ( 4 ) is adapted to be screwed onto the jointing tube ( 5 ); c. a plunger ( 11 ) fitted with a rod positioned to engage the self-closing valve core ( 7 ), and housing a lamina ( 18 ) that varies geometrical configuration from a resting configuration to a pressured configuration in response to a pressure greater than a first pre-established threshold value , which variation effects movement within the rod of a bistable valve fitted with a double closing member ( 22 ); d. a movable sealing member ( 10 ) connected to the plunger ( 11 ), which movable sealing member ( 10 ) delimits, with respect to the envelope ( 1 ), at least a first chamber ( 15 ) located under the plunger ( 11 ), and at least a second chamber ( 16 , 20 ) located over the plunger ( 11 ); wherein the plunger ( 11 ) is movably positioned between the first chamber ( 15 ) and in the second chamber ( 16 , 20 ) with a range of motion of a magnitude sufficient to cause the opening of the self-closing valve core ( 7 ) from a closed position, said range of motion being limited between: i. a first limit stop position into which the plunger ( 11 ) is urged by the movable sealing member ( 10 ) in an absence of pressurization , and in which the plunger ( 11 ) does not cause the opening of the self-closing valve core ( 7 ), and ii. a second limit stop position, in which the plunger ( 11 ) separates a third chamber ( 26 ) from the first chamber ( 15 ) by sealingly contacting a gasket ( 25 ) and causes the opening of the self-closing valve core ( 7 ); wherein this second limit stop position is successively maintained only if the difference between: 1. the pressure in the second chamber ( 16 , 20 ), the value of which reaches the value in of the tire during the loading phase of the device, and 2. the pressure in the first chamber ( 15 ), which is connectable to atmospheric pressure is maintained higher than a first pre-established threshold value, so that a resultant thrust acting on the plunger ( 11 ) is higher than the forces of the valve spring ( 8 ) and the movable sealing member ( 10 ); and e. means for used signalling the configuration of the lamina ( 18 ) or the position of the plunger ( 11 ), whereby the device indicates if the pressure in the tire exceeds or not said first pre-established threshold value.