Tire pressure sensor and sensing system
First Claim
1. A tire pressure sensor comprising:
- an actuator responsive to a known range of tire pressure to move through a known range of travel with a one-to-one correspondence between tire pressure and actuator position,circuit means includinga plurality of switches actuable magnetically by the actuator and arranged so as to divide said range of travel of the actuator into a plurality of detection fields, each of which fields is characterized by a unique combination of actuated and unactuated switches, and further includinga plurality of resonators, each of which has a different resonant frequency and is connected to at least one of said switches, andmeans for inputting to the circuit means a first signal comprising the different resonant frequencies and for outputting a second signal generated by the resonators whereby, for each of said detection fields, the resonators output a unique combination of frequencies.
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Accused Products
Abstract
A wheel-mounted tire pressure sensor employs a Bourdon tube which deforms in relation to tire pressure to drive a pivotal arm. Opposite ends of the arm support magnets which can close reed switches arrayed around the path of travel of the magnets. The reed switches are connected to passive resonators in such a way that for each of a number of regions of travel of the arm, a unique combination of resonators is activated. The resonators are connected to a wheel-mounted antenna which faces a stationary antenna. Frequency signal matching the frequencies of the resonator are sequentially broadcast by the stationary antenna to the resonators, which are excited to oscillate if activated by the corresponding switch or switches. The excited resonator broadcast their frequencies back to the stationary antenna and to a display unit which decodes the combination of resonator frequencies to display the corresponding tire pressure. An optional alarm unit includes a memory unit which holds maximum safe speed values for each of the detectable ranges of tire pressure. The sensed tire pressure is converted to the corresponding speed limit value which is then compared to the sensed vehicle speed. If actual vehicle speed exceeds the preset safe value, an alarm is generated.
83 Citations
12 Claims
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1. A tire pressure sensor comprising:
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an actuator responsive to a known range of tire pressure to move through a known range of travel with a one-to-one correspondence between tire pressure and actuator position, circuit means including a plurality of switches actuable magnetically by the actuator and arranged so as to divide said range of travel of the actuator into a plurality of detection fields, each of which fields is characterized by a unique combination of actuated and unactuated switches, and further including a plurality of resonators, each of which has a different resonant frequency and is connected to at least one of said switches, and means for inputting to the circuit means a first signal comprising the different resonant frequencies and for outputting a second signal generated by the resonators whereby, for each of said detection fields, the resonators output a unique combination of frequencies. - View Dependent Claims (2, 3, 4, 5, 6, 12)
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7. A tire pressure sensing system for a vehicle comprising:
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a tire pressure sensor disposed on the wheel of the tire to be monitored and responsive to the air pressure within said tire to broadcast a wireless electromagnetic signal encoded to indicate which of a plurality of ranges the air pressure within said tire falls, said sensor including an actuator responsive to a known range of tire pressure to move through a known range of travel with a one-to-one correspondence between tire pressure and actuator position;
circuit means including a plurality of switches actuable magnetically by the actuator and arranged so as to divide said range of travel of the actuator into a plurality of detection fields, each of which fields is characterized by a unique combination of actuated and unactuated switches, and further including a plurality of resonators, each of which has a different resonant frequency and is connected to at least one of said switches; and
means for supplying to the circuit means a first signal comprising the different resonant frequencies and braodcasting a second signal generated by the resonators whereby, for each of said detection fields, the resonators output a unique combination of frequencies; anda reception and display unit responsive to said broadcast signal to display the sensed tire pressure. - View Dependent Claims (8, 9, 10, 11)
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Specification