US 4,553,059 A · Piezoelectric actuator and a piezoelectric pump injector incorporating the same

Abstract

A piezoelectric actuator comprises a housing having an inside cavity in which is mounted a column of piezoelectric elements having interleaved electrodes. The column of piezoelectric elements is mounted within a sealed enclosure which divides the inside cavity of the housing into an inner space receiving the column of piezoelectric elements and an outer space. The inner space is filled with a flowable, electrically insulative, thermally conductive material such as silicone oil held in direct contact with and in a heat transfer relationship with the column of piezoelectric elements. The silicone oil serves to isolate the column of piezoelectric elements and the electrodes from moisture and other foreign materials that would otherwise affect an insulation breakdown voltage. A cooling liquid is adapted to be circulated through the outer space surrounding the enclosure to absorb heat transferred thereto from the column of piezoelectric elements through the flowable thermally conducting material. The piezoelectric actuator may be incorporated with a fuel injection nozzle to form a pump injector which pressurizes and injects fuel at each energization of the column of piezoelectric elements.

Claims9

Dependent claims

A piezoelectric actuator comprising:

a hollow casing having an axial cavity;
a column of piezoelectric elements received coaxially in said cavity and supported at an end by said casing;
means for applying an electric field to said column of piezoelectric elements to develop piezoelectric stress therein causing displacement of the other end of said column of elements;
output means connected to said other end of the column of piezoelectric elements for transmitting the displacement of said other end to the outside of said casing;
an axially deformable enclosure fluid-tightly surrounding said column of piezoelectric elements and disposed at least in part between said casing and said column of piezoelectric elements to divide said cavity into an outer space and a sealed inner space;
a flowable, electrically insulative, thermally conductive material filled in said inner space;
and
means for circulating a cooling medium through said outer space.

5 more elements

Dependencies are inferred from the claim text.

Piezoelectric actuator and a piezoelectric pump injector incorporating the same

Life of this patent

Piezoelectric actuator and a piezoelectric pump injector incorporating the same

Life of this patent

Abstract

Claims9