The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 20, 1997
Filed:
Feb. 21, 1995
Dale A Knutson, Nashotah, WI (US);
George R Steber, Mequon, WI (US);
Applied Power Inc., Butler, WI (US);
Abstract
A piezo-electrically actuated hydraulic valve has a nozzle type seat and a piezo-electric actuator in a plane orthogonal to the axis of the nozzle. The actuator includes a piezo-ceramic layer laminated to an electrode sheet, so that the composite is in sheet form and parallel to the plane of the seat. The electrode sheet has opposite edges which extend beyond the piezo-ceramic layer and are clamped by the housing of the valve so that the center of the actuator is positioned over the seat, and in the preferred embodiment normally closes the seat. When an electric field is applied to the piezo-ceramic layer, the actuator bows or dishes so as to displace relative to the nozzle. The electric field may be applied proportionally, in which case the actuator displaces proportionally to the field applied, the field may be applied as a pulse width modulated signal, in which case the displacement of the actuator also modulates. The actuator has an electrode coating applied over the ceramic layer, which may be divided into motor and generator sub-areas, and an area of the coating is absent where the ceramic layer seats against the nozzle. Rectangular and circular actuators are disclosed.