Piezoelectric device for injector

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 applied 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-titante composition being adjusted so that said piezoelectric device has a change ratio of displacement of 9% or below when a frequency of the applied voltage is changed from 1 Hz to 200 Hz under the state where an AC voltage is applied so that an electric field intensity of 0 to 1.5 kV/mm is generated by a sine wave while a preset load of 500N is applied to said piezoelectric device.

A piezoelectric device for an injector, built in 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 applied voltage;
• and
• said piezoelectric layers and said internal electrode layers being alternately laminated;
• the composition of said piezoelectric layers being a lead zirco-titante composition, the components of said lead zirco-titante composition being adjusted so that the displacement increases with the rise of temperature within the range of −40° C. to 150° C.

A piezoelectric device for an injector, built in 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 applied voltage;
• and
• said piezoelectric layers and said internal electrode layers being alternately laminated;
• the composition of said piezoelectric layers being a lead zirco-titante composition, the components of said lead zirco-titanate composition being adjusted so that said piezoelectric devices has a dielectric loss of 8% or below calculated from a P-E hysteresis.

A method of a piezoelectric device to generate driving force of an injector, the piezoelectric device having a plurality of piezoelectric layers and a plurality of internal electrode layers, the method comprising:

• applying a voltage to the plurality of internal electrode layers;
• generating displacement in the piezoelectric layers in proportion to the applied voltage;
• and
• establishing a relation d(0.1 Ec)/d(1.2 Ec)>0.43, 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 500 N 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.

A method of using a piezoelectric device to generate a driving force of an injector, the piezoelectric device having a plurality of piezoelectric layers and a plurality of internal electrode layers, the method comprising:

• applying a voltage to the plurality of internal electrode layers;
• generating displacement in the piezoelectric layers in proportion to the applied voltage;
• and
• wherein said piezoelectric device has a change ratio of displacement of 9% or below when a frequency of the applied voltage is changed from 1 Hz to 200 Hz under the state where an a frequency of the applied so that an electric field intensity of 0 to 1.5 kV/mm is generated by a sine wave while a preset load of 500 N is applied to said piezoelectric device.

A method of using a piezoelectric device to generate a driving force of an injector, the piezoelectric device having a plurality of piezoelectric layers and a plurality of internal electrode layers, the method comprising:

• applying a voltage to the plurality of internal electrode layers;
• and
• generating displacement in the piezoelectric layers in proportion to the applied voltage;
• wherein the displacement increases with the rise of temperature within the range of −40° C. to 150° C.

A method of using a piezoelectric device to generate a driving force of an injector, the piezoelectric device having a plurality of piezoelectric layers and a plurality of internal electrode layers, the method comprising:

• applying a voltage to the plurality of internal electrode layers;
• and
• generating displacement in the piezoelectric layers in proportion to the applied voltage;
• wherein said piezoelectric device has dielectric loss of 8% or below calculated from a P-E hysteresis.