| 摘要 |
An electronic control unit configured to provide a pulse-width-modulated signal controlling opening of a valve 14 providing air and fuel vapour from a collector unit 12, used to collect fuel vapour from a fuel tank 10, to an engine 16, the PWM signal being modified by a variable slew rate. Preferably the duty cycle of the PWM signal is increased by the slew rate according to a predetermined pattern having a stage with a low slew rate corresponding to an opening range of the valve that produces a rapid increase in the fuel flow rate and one or more stages of increased slew rates corresponding to a slow increase, or substantially no increase, in flow rate. The ECU may calculate the slew rate using a look-up table or an algorithm. Also claimed is a method of operation. The ECU allows for better management of fuel flow from the collector to the engine. |
