Caterpillar Inc.

Larry Glenn Waterfield

Christopher F Gallmeyer

Richard H Holtman

Clifford E Cotton, Iii

Glen F Forck

Jerome P Maushard

A piezoelectric actuator includes at least one piezoelectric bender that is deformable between a first arcuate shape and a second arcuate shape that have different curvatures. A resistance device includes a moveable portion in contact with the piezoelectric bender throughout its deformation from the first shape to the second shape. In addition, the resistance device is operable to resist the deformation, preferably by resisting a change in the transverse dimension of the piezoelectric bender through a friction interaction. By resisting transverse dimension changes in the piezoelectric bender, the axial force produced by the actuator can be increased, and the same structure can compensate for wear that could otherwise undermine performance after many deformation cycles. The piezoelectric actuator finds particular application in fast valves, such as those associated with pressure switching in fuel injection systems.

Piezoelectric bender with increased activating force, and valve using same

An exhaust valve apparatus for an internal combustion engine exhaust valve having a thermally prestressed bender actuator, which moves through a displacement in response to a command signal from a control unit. An actuator drive responsive to motion of the thermally prestressed bender actuator operates an exhaust valve actuator system, which, in turn, operates the exhaust valve. The thermally prestressed electroactive bender actuator and the exhaust valve actuator system operate the exhaust valve to effect engine compression braking.

Method and apparatus for operating an internal combustion engine exhaust valve for braking

The present invention provides methods and apparatus for controlling an electric field across a piezoelectric device. A temperature determining device transmits a temperature signal indicative of a temperature of the piezoelectric device. A control device receives the temperature signal and a first control signal indicative of a desired displacement of the piezoelectric device. The control device transmits a second control signal to the piezoelectric device as a function of the temperature signal and the control signal. The second control signal creates the electric field across the piezoelectric device, when the temperature of the piezoelectric device is below a predetermined threshold, having a magnitude above a normal operating range for the piezoelectric device.

Method and apparatus for compensating for temperature induced deformation of a piezoelectric device

A piezoelectric actuator of multiple piezoelectric layers in an integrally bonded laminate structure. Alternating layers of electrically active ceramic material and conductive or non-conductive substrate material are stacked with layers of conductive or non-conductive thermally activated adhesive therebetween. The stacked layers are heated to flow the adhesive and subsequently cooled to effect an integral bonding of the layers and a doming of the stacked device. Conductive substrate materials and adhesive materials may be used, with every other substrate layer being reverse poled to create alternating positive and negative electrode substrate layers capable of applying an electric field to active ceramic layers therebetween. Alternatively, electrically active layers are provide with thin metal electrode layers on opposing surfaces which are capable of applying an electric field to active ceramic layers therebetween.

Piezoelectric actuator device

A control system for temperature compensating a piezoelectric device. The control system includes a temperature compensating circuit that is operable to receive a control signal corresponding to a desired position of the piezoelectric device and compensate the control signal in response to an estimated temperature proximate the piezoelectric device. A piezoelectric device control circuit is operable to receive the temperature compensated control signal and generate a control signal that is adapted to drive the piezoelectric device to the desired position. The temperature proximate the piezoelectric device may be estimated from an estimated ferroelectric polarization of the piezoelectric device or from a temperature sensor.

Method and apparatus for temperature compensating a piezoelectric device

A system for controlling the operation of a piezoelectric device including a control system operable to generate a first control signal representing a desired charge on the piezoelectric device and corresponding to a desired position of a piezoelectric device. The control system further includes a charge control circuit responsive to the first control signal for providing a charge control signal to a device control circuit. The device control circuit provides a command signal that causes the piezoelectric device to move to the desired position.

Method and apparatus for controlling a piezoelectric device

A control system for controlling position and velocity of a piezoelectric device. The control system includes a position control circuit that is operable to receive a control signal corresponding to a desired position of the piezoelectric device, and to compare the control signal to an estimated position of the piezoelectric device. The position control circuit generates a position error control signal that is adapted to drive the piezoelectric device to the desired position. The control system may further include a velocity control circuit that is operable to receive the position error control signal and generate a control signal that is adapted to drive the piezoelectric device to the desired position and at the desired velocity according to a predetermined velocity profile.

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Peoria, IL, United States of America

Larry Glenn Waterfield