Method for measuring high frequency resistance in diesel engine lubrication oil
First Claim
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1. A method for measuring high frequency resistance in 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, wherein the oil acts as a resistor between the plates;
connecting an inductor in series with the capacitor, wherein the capacitor and the inductor collectively provide a resonant circuit;
sweeping a predetermined range of high frequency voltage through the resonant circuit;
sensing resonance of the resonant circuit, whereat an inductive reactance of the inductor equals and is opposite to a capacitive reactance of the capacitor at a frequency within said predetermined range; and
determining resistance of the oil between the plates of the capacitor at the frequency.
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Abstract
Soot content in Diesel engine lubrication oil is determined using electrical resistance measurements of the oil at high frequency. A sensor in the form of a capacitor is immersed in the oil, wherein the oil serves as a dielectric between the plates. The capacitance and resistance between the plates change as a function of engine oil condition. An inductor is placed in series with the sensor, and high frequencies are sweeped over a range to find resonance where the capacitive and inductive reactances cancel. At this frequency, the resistance of the oil is measured and the condition of the oil thereby determined.
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Citations
8 Claims
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1. A method for measuring high frequency resistance in 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, wherein the oil acts as a resistor between the plates;
connecting an inductor in series with the capacitor, wherein the capacitor and the inductor collectively provide a resonant circuit;
sweeping a predetermined range of high frequency voltage through the resonant circuit;
sensing resonance of the resonant circuit, whereat an inductive reactance of the inductor equals and is opposite to a capacitive reactance of the capacitor at a frequency within said predetermined range; and
determining resistance of the oil between the plates of the capacitor at the frequency. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for measuring high frequency resistance in 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, wherein the oil acts as a resistor between the plates;
connecting an inductor in series with the capacitor, wherein the capacitor and the inductor collectively provide a resonant circuit;
sweeping a predetermined range of high frequency voltage through the resonant circuit;
sensing resonance of the resonant circuit, whereat an inductive reactance of the inductor equals and is opposite to a capacitive reactance of the capacitor at a frequency within said predetermined range, wherein said step of sensing comprises;
sensing a peak current value and a drive voltage value over the predetermined range of frequencies;
storing a peak current value; and
storing a drive voltage value;
determining resistance of the oil between the plates using the stored peak current and voltage values; and
determining an oil condition of the oil responsive to the resistance.
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8. A method for measuring high frequency resistance in 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, wherein the oil acts as a resistor between the plates;
connecting an inductor in series with the capacitor, wherein the capacitor and the inductor collectively provides a resonant circuit;
sweeping a predetermined range of high frequency voltage through the resonant circuit;
sensing resonance of the resonant circuit, whereat an inductive reactance of the inductor equals and is opposite to a capacitive reactance of the capacitor at a frequency within said predetermined range, wherein said step of sensing comprises sensing difference of phase between current and voltage over the predetermined range of frequencies;
determining resistance of the oil between the plates when the difference equals zero; and
determining an oil condition of the oil responsive to the resistance.
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Specification