Importance

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Abstract

To provide for extremely rapid operating conditions of the valve in an electrically controlled fuel injection system, that is, valve operation in the order of 10.sup.-5 seconds, for example, a pump (2, 62) provides pressurized fuel, and two, in push-pull operating valves (4, 64; 5, 65) are provided, in which one of the valves (4, 64) controls initiation of fuel injection, and the other one of the valves (5, 65) controls termination thereof; each one of the valves uses a spring-loaded valve element (18, 38', 38, 38'), operated by the pressure of the fuel to be injected, the valve elements being retained in a predetermined position by an electrically controlled operating unit (27, 47'; 47, 47') which has a positioning element operating in a positioning path having at least a component which is perpendicular to the operating direction of the valve element and which, as commanded by the control voltage applied thereto, clamps the valve element in a predetermined position, and thus prevents movement of the valve element even though fluid pressure is applied thereto. Preferably, the electrical control element is a stack of piezoelectric disks which, upon energizaton, expand in axial direction and press a clamping stem (26, 46'; 46, 46') the movable valve element (18, 38', 38, 38') in an operating bore of the valve unit or housing (16, 36).

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First Claim