Denso Corporation

Yutaka Yamada

Masayuki Kobayashi

Naoyuki Kawazoe

Kenji Funai

Ryo Katsura

Ken Mizutani

A fuel injector for an internal combustion engine is provided. The fuel injector has a simple structure so that it is easy to install and remove a piezoelectric valve actuator in and from the fuel injector, and to adjust fuel injection characteristics finely which allows the overall size of the fuel injector to be decreased. The fuel injector includes a housing to be installed in the engine and a structural element serving to install the piezoelectric valve actuator in the housing to be detachable easily. The piezoelectric valve actuator is retained in an actuator casing fitted in the housing so that it can expand or contract to move a needle valve. The actuator casing has an extensible portion in itself or is coupled to a bellows in alignment for enabling the piezoelectric valve actuator to expand, thereby allowing the size of the actuator casing to be minimized.

Structure of fuel injector using piezoelectric actuator

A piezoelectric device which is applicable, for example, as a drive source for a fuel injector comprises a plurality of piezoelectric layers and a plurality of inner electrode layers stacked alternately with each other. The outer peripheral side surfaces are formed with a pair of outer electrode layers electrically turned on alternately in such a manner that the inner electrode layers located adjacently to each other through the piezoelectric layers have different polarities. Second outer electrode layers configured of a conductive material having a larger breaking elongation than the first outer electrode layers, respectively, are formed on a pair of the first outer electrode layers.

Piezoelectric device for injector

Structure for transmitting displacement of a piezoelectric element includes a piston member. A distal-end plate portion has a receiving face adapted to be brought into direct contact with a distal-end face of the piston member. The distal-end face of the piston member is brought into direct contact with a mating member at a displacement transmitting face which is situated on an opposite side to the receiving face. End faces of a piezoelectric element in a displacement direction are maintained substantially in parallel to each other while the piezoelectric element is being driven. The contact configuration between the distal-end face and the receiving face is an annular and linear contact condition, whereby the piezoelectric element, the piston member and the distal-end plate portion are constructed so as to remain substantially stationary while the piezoelectric element is being driven.

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Suzuka, Japan

Yutaka Yamada