Method and apparatus for inferring engine oil temperature for use with an oil change indicator
AssigneeFord Motor Company
InventorsMichael J. Cullen, Stephen B. Zulczyk
Life of this patent
Estimating the term…
Abstract
An electronic engine controller infers the instantaneous temperature of lubricating oil in an engine by determining a steady state oil temperature value as a function of engine speed and aircharge, determining an oil temperature time constant as a function of mass air flow rate and determining the instantaneous oil temperature as a function of the steady state oil temperature and the oil temperature time constant. The engine controller also determines an oil change interval as a function of the inferred oil temperature and the number of engine revolutions.
Claims12
A method of determining an oil temperature value which is indicative of the temperature of lubricating oil within an internal combustion engine in a vehicle, comprising the steps of:
- determining a steady state oil temperature value as a function of an engine speed value which is indicative of the rotational speed of the engine, and an aircharge value which is indicative of an aircharge being drawn into the engine;
- determining, as a function of the aircharge value, a time constant value which is indicative of the rate of change of temperature in the engine;
- and
- determining the temperature of said oil as a function of said steady state oil temperature value and said time constant value.
In a vehicle which includes oil for lubricating engine components, an oil change indicator which provides an operator of the vehicle of the expiration of an oil change interval, and a means for generating an oil change reset signal which causes initiation of said oil change interval, a method for informing an operator of the vehicle of the expiration of said oil change interval, comprising, the steps
- (i) responding to said oil change reset signal by initializing an oil quality value which is indicative of the lubricating quality of said oil;
- (ii) inferring the temperature of said oil as a function of the rotational speed of the engine, aircharge entering an intake manifold of the engine, and engine coolant temperature;
- (iii) generating, as a function of said oil temperature, an oil stress value which is indicative of a rate at which the oil degrades;
- (iv) generating an oil use value as a function of said oil stress value and an engine revolution value;
- (v) modifying said oil quality value by adding said oil use value to said oil quality value;
- (vi) comparing said modified oil quality value to a predetermined quality value, which is indicative of a predetermined maximum oil life;
- (vii) providing a first indication to said vehicle operator if said modified oil quality value indicates an effective oil life which is greater than an oil life indicated by said predetermined quality value;
- and
- (viii) periodically repeating steps (ii)-(vii) during operation of said engine, said engine revolution value being indicative of a number of engine revolutions elapsed between execution of the steps (ii)-(vii) and the subsequent execution of the steps (ii)-(vii).
In a vehicle which includes lubricating oil for lubricating engine components, an oil change indicator which provides an operator of the vehicle of the expiration of an oil change interval, and a means for generating an oil change reset signal which causes initiation of said oil change interval, a system for informing an operator of the vehicle of the expiration of said oil change interval, comprising, in combination:
- means for initializing an oil quality value, which is indicative of the efficacy of said oil;
- means for inferring the temperature of said oil as a function of a first value indicative of the rotational speed of the engine, a second value indicative of aircharge entering an intake manifold of the engine, and a third value indicative of engine coolant temperature;
- and
- means for periodically altering, upon the passage of a variable number of engine revolutions, said oil quality value, comprising,
- means, responsive to said oil temperature for generating an oil stress value which is indicative of a rate at which the oil degrades;
- means for altering said oil quality value as a function of said oil stress value and a value indicative of said variable number of engine revolutions;
- means for comparing said altered oil quality value to a predetermined quality value, which is indicative of a predetermined maximum oil life;
- and
- means for providing a first indication to said vehicle operator if said altered oil quality value indicates an effective oil life which is greater than an oil life indicated by said predetermined quality value.
Dependencies are inferred from the claim text.