Fuel injection system

An injection system for delivering fuel under pressure directly to a fuel injection valve that discharge fuel for combustion, said system including an injection device comprising a pumping chamber, an electrically operated device continuously operable on fuel within said pumping chamber and consisting of the sole means for increaing the pressure on file delivered to said plumping chamber, said electrically operated device, when subjected to electrical energy, being effective to provide a rapid increase in localized fluid pressure in said pumping chamber solely through changes in the volume of said electrically operated device effected by the application of electrical energy to said electrically operated device, a discharge port from said pumping chamber in constant communication with said fuel injection valve for discharging only the fluid displaced by said localized pressure increase through said fuel injection valve, means for providing an energizing voltage to said electrically operated device, and control means for changing at least one characteristic of said energizing voltage selected from the group consisting of:

• the peak energizing voltage, the rate at which said energizing voltage is increased, the rate at which said energizing voltage is decreased, the duration of energization, and the frequency of energization.