Automatic engine oil change indicator system
First Claim
1. In a motor vehicle having an engine containing lubricating engine oil which has a useful life that varies in accordance with engine operating conditions and apparatus for determining the remaining useful life of the engine oil in engine operation from the engine oil temperature, apparatus for determining the engine oil temperature without direct measurement thereof comprising, in combination:
- means for storing a datum having a first value indicating that the engine oil temperature is in a warming range and a second value indicating that the engine oil temperature is in an equilibrium range, the stored datum being set to the first value at the beginning of engine operation;
means responsive to the first value of the stored datum to calculate the engine oil temperature To according to a warmup equation To =k1 +k2 Tr +k3 Ff, wherein Tr is a reference temperature indicative of engine oil temperature at the beginning of engine operation, Ff is a firing factor proportional to the number of combustion firings since the beginning of engine operation, and k1, k2 and k3 are constants;
means responsive to the second value of the stored datum to calculate the engine oil temperature To according to an equilibrium equation To =k4 +k5 Te +k6 Se, wherein Te is an engine temperature indicative of engine oil temperature, Se is engine rotational speed, and k4, k5 and k6 are constants;
means for storing the calculated engine oil temperature To for use by the apparatus for determining the remaining useful life of the engine oil; and
means for setting the stored datum to its second value when the calculated engine oil temperature To exceeds a predetermined warmup temperature.
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Accused Products
Abstract
An apparatus and method is disclosed for indicating useful life of motor vehicle angine oil during engine operation based on engine oil temperature without direct measurement thereof. Following the initiation of engine operation, engine oil temperature is calculated from a warmup equation until calculated engine oil temperature exceeds a warmup reference, whereupon it is calculated from an equilibrium equation, both of which equations being linear combinations of engine operating parameters other than engine oil temperature itself. The warmup equation includes a constant term, a reference temperature term fixed at the begining of engine operation and a term increasing proportionally with the number of engine cylinder firings. The equilibrium equation includes a constant term, an engine temperature term and a term proportional to engine speed and may also include a term proportional to an engine cooling factor.
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Citations
14 Claims
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1. In a motor vehicle having an engine containing lubricating engine oil which has a useful life that varies in accordance with engine operating conditions and apparatus for determining the remaining useful life of the engine oil in engine operation from the engine oil temperature, apparatus for determining the engine oil temperature without direct measurement thereof comprising, in combination:
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means for storing a datum having a first value indicating that the engine oil temperature is in a warming range and a second value indicating that the engine oil temperature is in an equilibrium range, the stored datum being set to the first value at the beginning of engine operation; means responsive to the first value of the stored datum to calculate the engine oil temperature To according to a warmup equation To =k1 +k2 Tr +k3 Ff, wherein Tr is a reference temperature indicative of engine oil temperature at the beginning of engine operation, Ff is a firing factor proportional to the number of combustion firings since the beginning of engine operation, and k1, k2 and k3 are constants; means responsive to the second value of the stored datum to calculate the engine oil temperature To according to an equilibrium equation To =k4 +k5 Te +k6 Se, wherein Te is an engine temperature indicative of engine oil temperature, Se is engine rotational speed, and k4, k5 and k6 are constants; means for storing the calculated engine oil temperature To for use by the apparatus for determining the remaining useful life of the engine oil; and means for setting the stored datum to its second value when the calculated engine oil temperature To exceeds a predetermined warmup temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a motor vehicle having an engine containing lubricating engine oil which has a useful life that varies in accordance with engine operating conditions and apparatus for determining the remaining useful life of the engine oil in engine operation from engine oil temperature, a method for determining the engine oil temperature without direct measurement thereof comprising the steps of:
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storing a datum having a first value indicating that the engine oil temperature is in a warming range and a second value indicating that the engine oil temperature is in an equilibrium range; setting the stored datum to the first value at the beginning of engine operation; calculating the engine oil temperature To, when the stored datum has the first value, according to a warmup equation To =k1 +k2 Tr +k3 Ff, wherein Tr is a reference temperature indicative of engine oil temperature at the beginning of engine operation, Ff is a firing factor proportional to the number of combustion firings since the beginning of engine operation, and k1, k2 and k3 are constants; calculating the engine oil temperature To, when the stored datum has the second value, according to an equilibrium equation To =k4 +k5 Te +k6 Se, wherein Te is an engine temperature, Se is engine rotational speed, and k4, k5 and k6 are constants; storing the calculated engine oil temperature To for use by the apparatus for determining the remaining useful life of the lubricating oil; and setting the stored datum to its second value when the calculated engine oil temperature To exceeds a predetermined warmup temperature. - View Dependent Claims (11, 12, 13, 14)
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Specification