Fuel injector with variable actuator boosting

A fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, the injector comprising

• an injection valve member that is directly actuatable by a piezoelectric actuator, the injection valve member being contained in a nozzle body, and moved into a closed position by a spring element, and
• a hydraulic boosting device between the piezoelectric actuator and the injection valve member, the hydraulic boosting device adapting the force exerted by the piezoelectric actuator to the opening force of the injection valve member, wherein the boosting device includes a sleeve-shaped guide body and further comprising an inner spring element that rests against the piezoelectric actuator and prestresses the sleeve-shaped guide body.

A fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, the injector comprising

• an injection valve member that is directly actuatable by a piezoelectric actuator, the injection valve member being contained in a nozzle body, and moved into a closed position by a sprint element, and
• a hydraulic boosting device between the piezoelectric actuator and the injection valve member, the hydraulic boosting device adapting the force exerted by the piezoelectric actuator to the opening force of the injection valve member, wherein the boosting device comprises a first piston and a second piston that are hydraulically coupled to each other by a coupling chamber, wherein the boosting device includes a sleeve-shaped guide body, and further comprising an inner spring element that rests against the piezoelectric actuator and prestresses the sleeve-shaped guide body.

A fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, the injector comprising

• an injection valve member that is directly actuatable by a piezoelectric actuator, the injection valve member being contained in a nozzle body, and moved into a closed position by a sprint element, and
• a hydraulic boosting device between the piezoelectric actuator and the injection valve member, the hydraulic boosting device adapting the force exerted by the piezoelectric actuator to the opening force of the injection valve member, wherein the boosting device comprises a first piston and a second piston that are hydraulically coupled to each other by a coupling chamber and wherein one piston of the boosting device is acted on by an additional spring element contained in a hydraulic chamber of the nozzle body, by a control chamber spring element contained in the control chamber, and a spring element contained in the coupling chamber.

A fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, the injector comprising

• an injection valve member that is directly actuatable by a niezoelectric actuator, the injection valve member being contained in a nozzle body, and moved into a closed position by a spring element, and
• a hydraulic boosting device between the piezoelectric actuator and the injection valve member, the hydraulic boosting device adapting the force exerted by the piezoelectric actuator to the opening force of the injection valve member, wherein once an opening pressure PO of the injection valve member has been reached, the boosting device acts with a first boosting ratio i1=dA2/dN2, where dA is the diameter of the first piston and dN is the diameter of the injection valve member.

A fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, the injector comprising

• an injection valve member that is directly actuatable by a piezoelectric actuator, the injection valve member being contained in a nozzle body, and moved into a closed position by a spring element, and
• a hydraulic boosting device between the piezoelectric actuator and the injection valve member, the hydraulic boosting device adapting the force exerted by the piezoelectric actuator to the opening force of the injection valve member, wherein one piston comprises a collar, and wherein, when the collar is resting against the sleeve-shaped guide body, the boosting device acts with the boosting ratio i2=dV2, where dV is the diameter of the sleeve-shaped guide body and dN is the diameter of the injection valve member.

A fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, the injector comprising

• an injection valve member that is directly actuatable by a piezoelectric actuator, the injection valve member being contained in a nozzle body, and moved into a closed position by a spring element, and
• a hydraulic boosting device between the piezoelectric actuator and the injection valve member, the hydraulic boosting device adapting the force exerted by the piezoelectric actuator to the opening force of the injection valve member, wherein the boosting device comprises a first piston and a second piston that are hydraulically coupled to each other by a coupling chamber and wherein, in its neutral position, the second piston of the boosting device is either supported with its piston end surface against a flat surface of the nozzle body or supported with a pin directly against the injection valve member.