Patent ID: 6787975
Filing Date: 2004-09-07
Classification: F02M,H01L

Abstract:
A piezoelectric device for an injector, built into an injector and generating driving force of said injector, comprising:a plurality of piezoelectric layers generating displacement in proportion to a voltage applied to said piezoelectric layers; a plurality of internal electrode layers for supplying the voltage; and said piezoelectric layers and said internal electrode layers being alternately laminated; the composition of said piezoelectric layers being a lead zirco-titanate composition, the components of said lead zirco-titanate composition being adjusted so that a relation d(0.1 Ec)/(1.2 Ec)>0.43 is established, where Ec is coercive electric field which causes the changing of polarizing direction, between an apparent piezoelectric constant d(1.2 Ec) calculated from static elongation when an electric field of 1.2 Ec is applied to said piezoelectric device in the same direction as a polarizing direction while a preset load of 500N is applied to said piezoelectric device, and an apparent piezoelectric constant d(0.1 Ec) calculated from static elongation when an electric field of 0.1 Ec is applied to said piezoelectric device in the same direction as the polarizing direction.