Piezoelectric device for injector
AssigneeDenso Corporation
InventorsMasayuki Kobayashi, Hidekazu Hattori
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Abstract
A piezoelectric device for an injector is built into an injector and generates driving force of the injector. A relation d(0.1Ec)/d(1.2Ec)≧0.50 is established between an apparent piezoelectric constant d(1.2Ec) calculated from static elongation when an electric field of 1.2 Ec is applied to the piezoelectric device in the same direction as a polarizing direction while a preset load of 500 N is applied to the piezoelectric device, and an apparent piezoelectric constant d(0.1Ec) calculated from static elongation when an electric field of 0.1 Ec is applied to the piezoelectric device in the same direction as the polarizing direction. The piezoelectric device so fabricated has high durability and can be used for a long time.
Claims17
A piezoelectric device for an injector built in an injector and generating driving force of said injector, characterized in that:
- said piezoelectric device is fabricated by alternately laminating a plurality of piezoelectric layers expanding and contracting in proportion to an applied voltage and a plurality of internal electrode layers for supplying the applied voltage;
- at least a part or the whole of a sectional shape of said piezoelectric device crossing at right angles the laminating direction is arcuate;
- and
- said piezoelectric device is accommodated in a circular cylindrical accommodation space;
- wherein a proximity ratio expressed by (B/A)×100 (%), where A is a length of the whole circumference of a circumscribed circle of said piezoelectric device and B is the sum of length of circumferential portions having a distance of 0.2 mm or below between said circumscribed circle and said piezoelectric device, is larger than 17%.
A piezoelectric device for an injector built in an injector and generating driving force of said injector, characterized in that:
- said piezoelectric device is fabricated by alternately laminating a plurality of piezoelectric layers expanding and contracting in proportion to an applied voltage and a plurality of internal electrode layers for supplying the applied voltage;
- at least a part or the whole of a sectional shape of said piezoelectric device crossing at right angles the laminating direction is arcuate;
- and
- said piezoelectric device is accommodated in a circular cylindrical accommodation space;
- wherein a proximity ratio expressed by (B/A)×100 (%), where A is a length of the whole circumference of a circumscribed circle of said piezoelectric device and B is the sum of length of circumferential portions having a distance of 0.2 mm or below between said circumscribed circle and said piezoelectric device, is 32% or more.
A piezoelectric device for an injector built in an injector and generating driving force of said injector, characterized in that:
- said piezoelectric device is fabricated by alternately laminating a plurality of piezoelectric layers expanding and contracting in proportion to an applied voltage and a plurality of internal electrode layers for supplying the applied voltage;
- at least a part or the whole of a sectional shape of said piezoelectric device crossing at right angles the laminating direction is arcuate;
- and
- said piezoelectric device is accommodated in a circular cylindrical accommodation space;
- wherein at least two side surface flat portions having a width of 2.5 mm or more are disposed on the side surface parallel to the laminating direction.
Dependencies are inferred from the claim text.