Viscosity detection using starter motor

Abstract

Various methods for inferring oil viscosity and / or oil viscosity index in an internal combustion engine are provided. In one example, a new control method comprises cranking the engine during a start mode with an electric motor connected to a substantially constant source of electrical power, inferring engine oil viscosity based at least on engine oil temperature and speed of the engine while being cranked by the electric motor during the start mode, and correcting an operating parameter of the engine based on the inferred engine oil viscosity.

Description

technical field [0001] The field of the disclosure relates to engine control with varying oil viscosity and detection thereof. Background technique [0002] Oil viscosity has a direct effect on engine friction, which in turn affects engine torque output and idle speed. Therefore, engine friction should be estimated or assumed using various parts of the engine control strategy, including idle speed control and electronic throttle control. Oil viscosity also affects oil pressure, which in turn affects systems like VCT (Variable Cam Timing) that rely on oil pressure to operate. [0003] For conventional engine oils, the viscosity changes dramatically with temperature (ie, low viscosity index). New motor oils are being developed with higher viscosity indexes, so their viscosity changes less with temperature. [0004] Some engine control strategies include temperature regulators that help compensate for changes in oil viscosity. For example, lower temperatures, higher viscosi...

AI Technical Summary

Problems solved by technology

If the engine is refilled with a low viscosity index oil, the idle speed at cold temperatures will be lower than expected and the engine may stall

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