Caterpillar Inc.

Brian D Huggins

Adam J Gudat

Andrew Alfred Knitt

John F Szentes

Ali A Bitar

Frank B Walton

Matthew Daniel Fike

Mark T DeCou

Wesley E Jacobson

A particulate trap regeneration system is provided, which may include a particulate trap having a filter medium configured to remove one or more types of particulate matter from an exhaust flow of an engine and a regeneration device configured to reduce an amount of particulate matter in the particulate trap, as well as a radio frequency-based particulate loading monitoring system configured to determine an amount of particulate matter trapped by the filter medium. The particulate loading monitoring system may include at least one radio frequency transmitting probe configured to transmit radio frequency signals of predetermined magnitude and predetermined frequency toward the filter medium and at least one radio frequency receiving probe configured to receive and measure the magnitude of received radio frequency signals that pass through the filter medium. Further, the system may include a temperature sensing device configured to take a temperature measurement indicative of a temperature of the particulate trap at the time the radio signals are received by the receiving probe and a controller, which may be configured to determine, based on the measured magnitude of received radio frequency signals, a particulate loading value indicative of the amount of particulate matter trapped in the filter medium. The controller may also be configured to perform a temperature compensation including modifying, based on the temperature measurement, at least one of the following: the measured magnitude of the received radio frequency signals that pass through the filter medium or the particulate loading value.

Radio frequency-based particulate loading monitoring system

Known linear position sensors suffer from inaccuracies owing to severe environmental conditions, such as temperature and humidity. Physical damage to sensors exposed to rugged work conditions is a limiting factor in the expected life of sensors used, for example, in the heavy equipment industry. A pair of loop antennas mounted internal to an extensible coaxial cavity respectively transmit and receive electromagnetic signals in the radio frequency range exciting a transverse electromagnetic field in the cavity when the frequency of the signal corresponds to the resonant frequency of the cavity. The resonant frequency of the cavity is primarily dependent upon the longitudinal length of the cavity. Therefore, a voltage controlled oscillator acts under the control of a sawtooth voltage waveform of a function generator to controllably deliver a variable frequency signal to the first loop antenna. An RF detector monitors the second loop antenna for an indication that the resonant frequency has been reached. At resonance a microprocessor samples the output of the VCO and correlates the resonant frequency to the length of the coaxial cavity. The sensor is particularly suited for use in the heavy equipment industry for detecting the extended length of hydraulic cylinders as it is highly insensitive to environmental conditions and protected from the work environment.

Linear position sensor using a coaxial resonant cavity

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Peoria, IL, United States of America

Brian D Huggins