Piezoelectric stack insulation
AssigneePZ Technology, Inc.
InventorCormac G. O'Neill
Life of this patent
Estimating the term…
Abstract
By filling the container of a piezoelectric stack with a dielectric fluid under sufficient pressure, or applying sufficient pressure to a solid dielectric, to maintain dielectric particle velocity and piezoelectric particle velocity substantially spaced, dielectric breakdown with consequent arc over and destruction of the piezoelectric stack is prevented.
Claims14
In apparatus of the type employing a plurality of piezoelectric discs having flat surfaces which are stacked serially, which have a dielectric medium applied to their radial surfaces, and which have a voltage applied to the opposing surfaces of said discs for the purpose of causing them to change their radial dimension in response thereto, said voltage having a rise time or fall time such that the particle velocity of the piezoelectric material exceeds the particle velocity of said dielectric medium when said voltage is applied resulting in a separation therebetween, the improvement comprising
- applying pressure continuously to said dielectric medium to increase its particle velocity to a value at which it will compensate for separation caused by the difference between its particle velocity and the particle velocity of said piezoelectric material to maintain said dielectric medium in contact with said piezoelectric material during the application of said voltage.
In apparatus employing a plurality of piezoelectric discs arranged serially in a stack and wherein said discs are in a chamber filled with an insulating fluid, and there are means for applying a voltage to opposite faces of the discs of said stack to achieve axial dimensional changes, said voltage having a rise time or fall time such that the particle velocity of the piezoelectric material exceeds the particle velocity of said insulating fluid when said voltage is applied resulting in a separation therebetween, the improvement comprising
- means for continuously pressurizing said insulating fluid in said chamber to a value which increases its particle velocity to compensate for separation caused by the difference between its particle velocity and the particle velocity of said piezoelectric material during the application of said voltage.
In apparatus of the type employing a plurality of piezoelectric disc having conductive flat surfaces which are stacked serially, and which have a voltage applied to the opposing surfaces of said discs for the purpose of causing them to change their radial dimension in response thereto, said voltage having a rise and/or fall time such that the particle velocity of the piezoelectric material exceeds the particle velocity of said dielectric medium when said voltage is applied, resulting in a separation therebetween, the improvement comprising
- inserting a metal disc having a plurality of holes between opposite faces of each pair of piezoelectric discs,
- bonding each of said pairs of piezoelectric discs together with a dielectric material through the holes in the metal disc between each pair of piezoelectric discs,
- encasing said plurality of piezoelectric discs in said dielectric material, and
- continuously applying pressure to said dielectric material encasing said plurality of piezoelectric discs to increase its particle velocity to a value at which it will substantially equal the particle velocity of said piezoelectric material during the application of said voltage.
In apparatus employing a stack of piezoelectric discs having conductive flat surfaces, which discs are arranged serially in a stack, and have a dielectric coating applied to their edges and wherein a voltage is applied to opposite surfaces of said discs causing them to change their radial dimensions in response thereto, means for preventing destructive arcing across discs caused by the particle velocity of said piezoelectric discs exceeding the particle velocity of said dielectric coating upon the application of said voltage comprising
- means for applying sufficient pressure to said dielectric coating to increase its particle velocity to a value at which it will maintain contact with said piezoelectric material during the application of said voltage.
In apparatus employing a stack of piezoelectric discs having conductive flat surfaces, which discs are arranged serially in a stack, wherein a voltage is applied to opposite surfaces of said discs causing them to change their radial dimensions in response thereto, means for preventing destructive arcing across said discs, comprising
- a metal disc inserted between each pair of piezoelectric discs,
- first dielectric means bonding together each pair of piezoelectric discs through the holes in each of said metal discs and covering the remaining surfaces of said piezoelectric discs, and
- second dielectric means for continuously applying sufficient pressure to said first dielectric means to maintain its particle velocity at a value whereby said first dielectric means will remain in contact with said piezoelectric discs during the rise and fall time of the voltage applied thereto.
In apparatus of the type employing a plurality of piezoelectric discs having flat surfaces which are stacked serially, which have a dielectric medium applied to their radial surfaces, and which have a voltage applied to the opposing surfaces of said discs for the purpose of causing them to change their radial dimension in response thereto, said voltage having a rise time or fall time such that the particle velocity of the piezoelectric material exceeds the particle velocity of said dielectric medium when said voltage is applied resulting in a separation therebetween, the method of preventing said separation comprising
- determining the particle velocity of said piezoelectric material upon the application of said voltage thereto,
- determining the pressure drop caused in said dielectric medium caused by the change in volume of said piezoelectric stack by the applied voltage,
- determining the pressure that has to be applied to said dielectric medium to cause it to have substantially the same particle velocity as said piezoelectric material upon the application of said voltage, and
- applying a pressure to said dielectric medium at least equal to the sum of said determined pressure drop and said determined pressure that has to be applied to said dielectric medium.
In apparatus of the type employing a plurality of piezoelectric discs having flat surfaces which are stacked serially, which have a pressurized dielectric medium applied to their radial surfaces, and which have a voltage applied to the opposing surfaces of said discs for the purpose of causing them to change their radial dimension in response thereto, whereby a drop in the pressure of said pressurized dielectric occurs, said voltage having a rise time or fall time such that the particle velocity of the piezoelectric material in response thereto and as a result of said pressure drop exceeds the particle velocity of said dielectric medium when said voltage is applied resulting in a separation therebetween, the method of preventing said separation comprising
- applying additional pressure continuously to said dielectric medium to increase the particle velocity of said dielectric medium to a value at which it will compensate for separation caused by the difference between its particle velocity and the particle velocity of said piezoelectric material to maintain said dielectric medium in contact with said piezoelectric material during the application of said voltage.
In apparatus employing a plurality of piezoelectric discs arranged serially in a stack and wherein said discs are in a chamber filled with a pressurized insulating fluid, and there are means for applying a voltage to opposite faces of the discs of said stack to achieve axial dimensional changes resulting in a drop in the pressure applied by said pressurized insulating fluid, said voltage having a rise time or fall time such that the particle velocity of the piezoelectric material in response thereto and also as a result of said pressure drop exceeds the particle velocity of said insulating fluid when said voltage is applied resulting in a separation therebetween, the improvement comprising
- means for increasing the particle velocity of said insulating fluid in said chamber to a value which compensates for separation caused by the difference to its particle velocity from the particle velocity of said piezoelectric material during the application of said voltage.
Dependencies are inferred from the claim text.