Claims
- 1. A method of estimating a temperature of crankcase oil in an internal combustion engine, comprising the steps of:determining an initial estimate of the oil temperature at engine start-up based on a duration of engine inactivity prior to said engine start-up; modeling a net heat flow through the oil during operation of the engine after start-up; and periodically determining a new estimate of the oil temperature based on the initial estimate and the modeled net heat flow.
- 2. The method of claim 1, wherein the step of modeling the net heat flow comprises the steps of:modeling a heat flow into the oil from combustion of an air/fuel mixture in the engine; modeling a heat flow out of the oil; and modeling the net heat flow according to a difference between the modeled heat flow into the oil and the modeled heat flow out of the oil.
- 3. The method of claim 2, wherein the heat flow into the oil is modeled as a function of the oil temperature estimate, an estimate of a combustion temperature of said air/fuel mixture, and an empirically determined heat transfer coefficient.
- 4. The method of claim 3, wherein said heat transfer coefficient is empirically determined as a function of a speed of said engine.
- 5. The method of claim 2, wherein the heat flow out of the oil is modeled as a summation of a heat flow from the oil to atmospheric air and a heat flow from the oil to an engine coolant, the heat flow to atmospheric air being modeled as a function of the oil temperature estimate, a temperature of atmospheric air and an oil-to-air heat transfer coefficient, and the heat flow to the engine coolant being modeled as a function of the oil temperature estimate, a temperature of the coolant and an oil-to-coolant heat transfer coefficient.
- 6. The method of claim 5, where the engine is installed in a motor vehicle, and the oil-to-coolant heat transfer coefficient is empirically determined as a function of a speed of said engine, a speed of the motor vehicle and a heat transfer rate of the coolant to atmospheric air.
- 7. The method of claim 6, wherein the heat transfer rate of the coolant to atmospheric air is determined as a function of an operating state of a fan that forces atmospheric air through a coolant radiator.
- 8. The method of claim 5, where the engine is installed in a motor vehicle, and the oil-to-air heat transfer coefficient is adjusted as a function of a speed of the motor vehicle.
- 9. The method of claim 8, including the steps of:detecting an engine idle condition; and adjusting the oil-to-air heat transfer coefficient as a function of the coolant temperature when said engine idle condition is detected.
- 10. The method of claim 1, wherein the step of periodically determining a new estimate of the oil temperature includes the steps of:estimating a change in oil temperature due to the modeled net heat flow; and determining the new estimate of oil temperature according to a sum of the initial estimate and the estimated change in oil temperature.
Parent Case Info
This application claims the benefit of Provisional application No. 60/286,591 filed Apr. 26, 2001.
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Kind |
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A |
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Foreign Referenced Citations (1)
Number |
Date |
Country |
2001182565 |
Jul 2001 |
JP |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/286591 |
Apr 2001 |
US |