Laminated piezoelectric element and jetting apparatus using same

Abstract

In a laminated piezoelectric element, a plurality of piezoelectric layers and a plurality of metal layers are alternately laminated. The metal layers include a plurality of high resistance metal layers having an electrical resistance higher than electrical resistances of the adjacent metal layers on the both sides. The high resistance metal layers are regularly arranged by sandwiching a pluralityof metal layers other than the high resistance metal layers. In another laminated piezoelectric element, a plurality of piezoelectric layers and a plurality of metal layers are alternately laminated,and at least one layer of the metal layers is composed of a plurality of partial metal layers arranged between the piezoelectric layers.

Description

technical field [0001] The present invention relates to a multilayer piezoelectric element (hereinafter sometimes simply referred to as "element") and an injection device, and more particularly to a multilayer piezoelectric element and an injection device suitable for long-term continuous driving under high voltage / high pressure. Background technique [0002] Conventionally, as a device using a multilayer piezoelectric element, there is a piezoelectric actuator in which piezoelectric layers and metal layers are alternately stacked. Piezoelectric actuators are generally classified into two types, one is a simultaneous firing type, and the other is a stacked type in which piezoelectric ceramics formed of one piezoelectric body and metal layers of a plate-like body are alternately stacked. Among them, from the viewpoint of lowering the voltage and reducing the manufacturing cost, a simultaneous firing type piezoelectric actuator is often used. Simultaneous firing type piezo ac...

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Problems solved by technology

For this reason, the stress accompanying the displacement concentrates around the central part of the stacking direction of the multi-layer piezoelectric element, causing problems such as cracks.

[0018] As the improvement method, although there are methods shown in Patent Documents 4 and 5, they are mostly used under harsh conditions such as high electric field and high pressure for long-term continuous operation. Under such conditions, it is still impossible to say that Sufficient improvement may cause stress to concentrate on the outer periphery of the center of the element, resulting in cracks, peeling, or changes in displacement

[0019] In particular, there is a high risk of occurrence of the above-mentioned problems in a simultaneous firing type multi-layer piezoelectric element or a type in which at least a part of the outer periphery of the piezoelectric body is constrained.

[0020] In addition, there may be a resonance phenomenon in which the displacement behavior of each piezoelectric layer is consistent, which may generate a sound, and generate a high-order harmonic signal that is an integer multiple of the driving frequency and become a noise component.

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