| 摘要 |
A method for estimating the composition of a fuel within an engine, comprises performing the following steps under ambient conditions: (a′) determining the ambient temperature of the fuel; (a) monitoring the fuel pressure inside a fuel rail of the engine over a period of time; (b) calculating at least one frequency component of the change in fuel pressure; (c) calculating the speed of sound transmission c on the basis of the at least one frequency component; and (d) estimating the composition of the fuel on the basis of the calculated speed of sound transmission at said ambient temperature. Suitably, the speed of sound transmission in the fuel is calculated using the equation: c=fλ, where the wavelength λ of the standing wave with frequency f is 2L, where L is the length of the fuel rail. Also described are methods for estimating the temperature of the fuel at a non-ambient temperature, and determining a fuels physical properties. Methods for controlling a fuel injection system in an engine according to the determined physical properties of the fuel and the resultant fuel injection system are also described. |
