Eldec Corporation

Bourns Instruments, Inc.

Mark Finefrock

Jeff Lamping

Bradley Smith

Craig Stephen Trommler

Jeffrey J Green

Roger L Krechmery

Jonathan Lumb

Jeff Green

Cold check gas pressure readings for the landing gear tires of an aircraft are obtained automatically during normal operation of the aircraft. The automated system (S, e.g.) includes monitoring aircraft data to determine that the aircraft is at rest on the ground (), and electronically monitoring the tire pressure (). When predetermined cold check conditions have been met; the tire pressure values are automatically stored with a timestamp () for later access by a user.

Tire pressure cold check system

The aircraft tire pressure loop link is formed of first and second single metal loops connected by parallel spaced apart metal shafts, and provides for coupling a magnetic field between a wheel hub coil and a tire pressure sensor coil to provide electromagnetic communication between a control unit connect to the wheel hub coil and a tire pressure sensor connected to the tire pressure sensor coil. The current induced in the first single metal loop travels the distance from the edge of the wheel axle coil to the periphery of the of the wheel rim to the second single metal loop, which generates the flux in the tire pressure sensor receiver coil necessary to power the tire pressure sensor.

Aircraft tire pressure loop link

A passive RFID transponder sensor system includes a sensor assembly having a focused field transponder antenna with a highly magnetically permeable transponder antenna stem, and a reader antenna with an electrical reader coil generating a magnetic field having magnetic flux extending between the reader antenna and a sensor assembly. The electrical transponder coil and the electrical reader coil are coupled by the magnetic field, so that information can be transferred to and from the sensor assembly through the magnetic field by which the electrical transponder coil and the electrical reader coil are coupled.

Focused field antenna for passive RFID tire pressure sensor tranponder

Focused field antenna for passive RFID tire pressure sensor transponder

The aircraft tire pressure loop link is formed of first and second single metal loops connected by parallel spaced apart metal shafts, and provides for coupling a magnetic field between a wheel hub coil and a tire pressure sensor coil to provide electromagnetic communication between a control unit connect to the wheel hub coil and a tire pressure sensor connected to the tire pressure sensor coil; the current induced in the first single metal loop travels the distance from the edge of the wheel axle coil to the periphery of the of the wheel rim to the second single metal loop, which generates the flux in the tire pressure sensor receiver coil necessary to power the tire pressure sensor.

In a digital transducer, the output of a piezoelectric transducer bridge is coupled to the input of a comparator whose output switches between two predetermined states. A series of digital values is generated in response to the state of the comparator output and is fed back to balance the bridge. Stored digital values control the span of the transducer.

Digital piezoresistive pressure transducer

A pressure transducer of the type employing a pressure-responsive diaphragm (11) with silicon piezoresistive strain gauges epitaxially deposited thereon is provided with integral digital thermal compensation of span shift and zero shift. The strain gauges are connected in a bridge circuit (30), and a differential voltage across the bridge circuit is amplified by an instrumentation amplifier (46). A temperature sensitive resistor (36) is deposited on the pressure-responsive diaphragm. This resistor is connected in a bridge circuit (35) the output of which is connected to an analog-to-digital (A/D) converter (54) which generates a digital number corresponding to the measured temperature of the piezoresistive strain gauges. This digital number is used to address pre-programmed correction data stored in a programmable read only memory (PROM) (53). The numerical correction data from the PROM is converted by a digital-to-analog (D/A) converter (55) to an analog correction signal. The D/A converter has two outputs which are alternately selected by a timing and control circuit (56) to provide thermal span shift and thermal zero shift correction signals. The thermal span shift signal is used to modify the excitation voltage of the piezoresistive strain gauge bridge circuit, while the thermal zero shift signal is added to the amplified voltage output of the bridge circuit. A simple analog circuit (58) provides linearity compensation.

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Lake Stevens, WA, United States of America

Mark Finefrock