Method of preventing cavitation in a fuel injector having a solenoid

Abstract

A method of fuel injection comprises the initial step of providing a fuel injector with a solenoid actuated control valve mounted in an actuation fluid cavity. The valve is biased to a first position but movable to a second position against the bias when the solenoid is energized. When in its first position, the actuation fluid cavity is opened to a high pressure actuation fluid inlet, but opened to a low pressure fluid actuation fluid drain when in its second position. In the next step, the desired amount of fuel to be injected is determined. An actuation duration for the solenoid corresponding to the desired amount of fuel is calculated. Then, it is determined whether the actuation duration corresponds to a cavitation zone of operation for the control valve. Next an injection event is initiated by moving the valve to open the actuation fluid cavity to the high pressure actuation fluid inlet. After the actuation duration, the control valve is moved toward the position that opens the low pressure actuation fluid drain. If it is determined that the injector was operating within the cavitation zone of operation, then the movement rate of the control valve while closing is slowed while it is moving to close the high pressure actuation fluid inlet. This slowing of the valve's closure sufficiently alters conditions within the injector that pressure does not drop to cavitation levels.