Tire pressure alarm
First Claim
1. A tire pressure alarm system for a vehicle having a frame with an operator compartment and mounted on wheels with inflatable tires and having an electrical storage battery comprising:
- a compact transmitter including a low pressure responsive, fixed frequency radio signal generator with a nominal input power less than 100 milliwatts, an electrical battery for said transmitter and magnetically actuable switch closure contacts located between said signal generator and said transmitter battery, all positioned on a vehicle wheel and having enabling electrical contacts in circuit and operable by an air pressure check valve of a vehicle tire mounted on said wheel, and rotatable with said wheel relative to the frame of said vehicle,a receiver secured to said vehicle frame proximate to said wheel and including;
an electromagnetic element for closing said magnetically actuable switch closure contacts only when said transmitter is rotated with said wheel into proximity therewith, and a radio frequency diode detector tuned to said radio frequency signal generator,an alarm located in the cab of said vehicle with a wired connection to said receiver, anda power connection leading from said vehicle electrical storage battery to said electromagnetic element and including a normally open disabling switch therein which is closed by a mechanism associated with vehicle operation.
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Accused Products
Abstract
An electrical tire pressure alarm circuit includes an actuating connection to the vehicle storage battery which is keyed through a normally open disabling switch. The switch may be controlled by the vehicle ignition, by a trailer coupling, or it may be manually actuated. The transmitter is located on the vehicle wheel and responds to low tire pressure with a fixed frequency radio signal from a nominal input power less than 20 milliwatts. The transmitter oscillator is a tuned inductance/capacitance transistor oscillator circuit. An electromagnetic relay coil positioned on the vehicle frame closes an enabling switch to the transmitter only when the transmitter has been rotated by the wheel to a position proximate thereto, and only when the disabling switch has been closed. An alarm indicating system is located in the vehicle cab and is wired to the receiver and powered by the vehicle storage battery.
37 Citations
9 Claims
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1. A tire pressure alarm system for a vehicle having a frame with an operator compartment and mounted on wheels with inflatable tires and having an electrical storage battery comprising:
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a compact transmitter including a low pressure responsive, fixed frequency radio signal generator with a nominal input power less than 100 milliwatts, an electrical battery for said transmitter and magnetically actuable switch closure contacts located between said signal generator and said transmitter battery, all positioned on a vehicle wheel and having enabling electrical contacts in circuit and operable by an air pressure check valve of a vehicle tire mounted on said wheel, and rotatable with said wheel relative to the frame of said vehicle, a receiver secured to said vehicle frame proximate to said wheel and including; an electromagnetic element for closing said magnetically actuable switch closure contacts only when said transmitter is rotated with said wheel into proximity therewith, and a radio frequency diode detector tuned to said radio frequency signal generator, an alarm located in the cab of said vehicle with a wired connection to said receiver, and a power connection leading from said vehicle electrical storage battery to said electromagnetic element and including a normally open disabling switch therein which is closed by a mechanism associated with vehicle operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification