Method of estimating engine lubricant condition
First Claim
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1. A method of estimating the useful life of lubricating oil in an internal combustion engine, comprising the steps of:
- measuring variables relating to operation of the internal combustion engine;
estimating a depletion rate for a TBN in the lubricating oil from the measured variables;
estimating an accretion rate for a TAN in the lubricating oil from the measured variables; and
determining a time span until the TBN and the TAN equal one another as an estimate of remaining useful life of the lubricating oil.
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Abstract
A motor vehicle having an internal combustion engine and a lubricating oil circulation system provides estimates of the distance remaining before an oil change becomes imperative. An indirect estimate of the depletion of various additives and the deterioration of oil operating characteristics is based on engine operating variables including oil temperature, ignition timing and engine load. The limit of depletion of total base number is dynamic, since it is set against total acid number and the two figures are independently calculated.
13 Citations
12 Claims
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1. A method of estimating the useful life of lubricating oil in an internal combustion engine, comprising the steps of:
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measuring variables relating to operation of the internal combustion engine;
estimating a depletion rate for a TBN in the lubricating oil from the measured variables;
estimating an accretion rate for a TAN in the lubricating oil from the measured variables; and
determining a time span until the TBN and the TAN equal one another as an estimate of remaining useful life of the lubricating oil. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A motor vehicle comprising:
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an internal combustion engine having a lubricating system;
a lubricating oil temperature sensor;
an engine crankshaft position sensor;
a fuel injection means for setting fuel flow controller responsive to the engine crankshaft position sensor and the fuel flow;
lubricating oil for circulating in the lubricating system, the lubricating oil including buffers for neutralizing acid infiltration of the oil and metal salts for enhancing the lubricity of the oil; and
data processing means programmed for equating oil temperature, fuel rates and ignition timing for estimating depletion of the buffers, accretion of acid, and depletion of the metal salts. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification