Temperature compensation method for soot sensor
First Claim
1. A method for determining characteristics of Diesel engine lubrication oil, comprising the steps of:
- immersing a capacitor in the oil such that the oil provides a dielectric between the plates thereof;
connecting an inductor in series with the capacitor, wherein the capacitor and the inductor collectively provide a resonance circuit;
varying a frequency of a high frequency voltage applied to the resonance circuit;
sensing when the resonance circuit is at resonance; and
using at least one of a resonant frequency and a resonant current to determine at least one of a soot content and a dielectric constant of the oil.
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Abstract
Certain characteristics of Diesel engine lubrication oil are determined. A sensor formed as a capacitor is immersed in the oil. An inductor is in series with the sensor, and a high frequency voltage with a varying frequency is applied to the resonance circuit formed by the inductor and capacitor. Resonance is sensed, and the resonant frequency and/or the resonant current are used to determine the soot content and/or the dielectric constant of the oil. The electronics temperature can be used to compensate for temperature variations in the resonant frequency and the electronics temperature and the oil temperature can be used to compensate for temperature variations in the resonant current. The compensated values are preferably used in the determination of soot content and the dielectric constant.
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Citations
29 Claims
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1. A method for determining characteristics of Diesel engine lubrication oil, comprising the steps of:
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immersing a capacitor in the oil such that the oil provides a dielectric between the plates thereof;
connecting an inductor in series with the capacitor, wherein the capacitor and the inductor collectively provide a resonance circuit;
varying a frequency of a high frequency voltage applied to the resonance circuit;
sensing when the resonance circuit is at resonance; and
using at least one of a resonant frequency and a resonant current to determine at least one of a soot content and a dielectric constant of the oil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification