Piezoelectric Actuator and Method for Producing the Same

Abstract

A method for producing a piezoelectric actuator has the following steps: providing a plurality of piezoelectric material layers ( 2 ) which can be assembled into a stack; applying electrode layers ( 3 ) each having a recess ( 4, 4′ ) to the plurality of piezoelectric material layers, such that an alternating sequence of piezoelectric material layers and electrode layers is formed in the stack, wherein electrode layers with a recess ( 4 ) in a first recess zone and electrode layers with a recess ( 4′ ) in a second recess zone which differs from the first recess zone are alternatingly formed in the stack; and providing a stress-relieving material ( 5 ) in the first and second recesses, the stress-relieving material exhibiting electrically insulating properties after the stack is sintered, and preventing the individual material layers from adhering to one another.

1 . A method for producing a piezoelectric actuator, comprising the following steps:
 Providing a number of layers of piezoelectric material able to be assembled into a stack;   Application of electrode layers comprising a recess in each case to the number of layers of piezoelectric material such that an alternating sequence of layers of piezoelectric material and electrode layers is produced in the stack, with electrode layers being provided alternately in the stack with a recess in a first recess zone and electrode layers with a recess in a second zone differing from the first recess zone; and   Provision of a stress-relieving material in the first and second recesses, which, after the stack is sintered, exhibits properties of electrical insulation and properties of preventing the adhesion of the individual material layers.   
   
   
       2 . The method according to  claim 1 , wherein
 a metallization paste containing a noble metal with a low diffusion capability of the electrically-conductive particles during sintering of the stack is printed as electrode layers onto the number of layers of piezoelectric material in each case.   
   
   
       3 . The method according to  claim 1 , wherein
 a paste containing noble metals with a very high diffusion capability of the electrically-conductive particles during sintering of the stack is printed into the recesses as stress-relieving material.   
   
   
       4 . The method according to  claim 1 , wherein
 ceramic green tapes are used as layers of piezoelectric material.   
   
   
       5 . The method according to  claim 1 , wherein
 each second electrode layer is embodied in the stack with a recess in a first corner zone and each electrode layer provided between said layers is embodied with a recess in a second corner zone lying opposite the first corner zone.   
   
   
       6 . The method according to  claim 1 , wherein
 the piezoelectric actuator is embodied with at least two holes running in a longitudinal direction, wherein the recesses of the first recess zone in the area of the one hole and the recesses of the second recess zone in the area of the other hole in the stack are provided in an alternating sequence, wherein the holes are able to be linked in each case with an electrical contacting.   
   
   
       7 . A piezoelectric actuator comprising:
 a number of layers of piezoelectric material assembled into a stack; and   with electrode layers, which are applied in each case to the number of layers of piezoelectric material such that an alternating sequence of piezoelectric material layers ( 2 ) and electrode layers is produced in the stack; and   electrode layers being provided with a stress-relieving recess in a first recess zone and electrode layers with a stress relieving recess in a second recess zone differing from the first recess zone alternating in the stack.   
   
   
       8 . The piezoelectric actuators according to  claim 7 , wherein
 the electrode layers consist of a metallization paste containing a noble metal with a low diffusion capability of the electrically-conductive particles during sintering of the stack.   
   
   
       9 . The piezoelectric actuator according to  claim 7 , wherein
 the number of layers of piezoelectric material are embodied as ceramic green tapes.   
   
   
       10 . The piezoelectric actuator according to  claim 7 , wherein
 each second electrode layer in the stack comprises a stress-relieving recess in a first corner area and each electrode layer provided between said layers comprises a stress-relieving recess in a second corner area lying opposite the first corner area.   
   
   
       11 . The piezoelectric actuator according to  claim 7 , wherein
 the piezoelectric actuator comprises at least two holes running in a longitudinal direction, wherein the recesses of the first recess zone in the area of the one hole and the recesses of the second recess zone in the area of the other holes in the stack is provided in alternating sequence, wherein the holes are able to be linked in each case with an electrical contacting.   
   
   
       12 . The piezoelectric actuator according to  claim 7 , wherein
 the electrode layers consist of a metallization paste containing silver-palladium.   
   
   
       13 . The method according to  claim 1 , wherein
 a metallization paste containing silver-palladium is printed as electrode layers onto the number of layers of piezoelectric material in each case.   
   
   
       14 . The method according to  claim 1 , wherein
 a paste containing silver is printed into the recesses as stress-relieving material.   
   
   
       15 . A piezoelectric actuator, comprising:
 a number of layers of piezoelectric material assembled into a stack;   electrode layers comprising a recess in each case to the number of layers of piezoelectric material such that an alternating sequence of layers of piezoelectric material and electrode layers is produced in the stack, wherein the electrode layers being provided alternately in the stack with a recess in a first recess zone and electrode layers with a recess in a second zone differing from the first recess zone; and   a stress-relieving material in the first and second recesses, which, after the stack is sintered, exhibits properties of electrical insulation and properties of preventing the adhesion of the individual material layers.   
   
   
       16 . The actuator according to  claim 15 , wherein
 a metallization paste containing a noble metal with a low diffusion capability of the electrically-conductive particles during sintering of the stack is printed as electrode layers onto the number of layers of piezoelectric material in each case.   
   
   
       17 . The actuator according to  claim 15 , wherein
 a paste containing noble metals with a very high diffusion capability of the electrically-conductive particles during sintering of the stack is printed into the recesses as stress-relieving material.   
   
   
       18 . The actuator according to  claim 15 , wherein
 ceramic green tapes are used as layers of piezoelectric material.   
   
   
       19 . The actuator according to  claim 15 , wherein
 each second electrode layer is embodied in the stack with a recess in a first corner zone and each electrode layer provided between said layers is embodied with a recess in a second corner zone lying opposite the first corner zone.   
   
   
       20 . The actuator according to  claim 15 , wherein
 the piezoelectric actuator is embodied with at least two holes running in a longitudinal direction, wherein the recesses of the first recess zone in the area of the one hole and the recesses of the second recess zone in the area of the other hole in the stack are provided in an alternating sequence, wherein the holes are configured to be linked in each case with an electrical contacting.