A miniature cryocooler activated by piezoelectric elements in resonance (Technion)
Stirling cycle-based cryocoolers employ mechanical compressors activated by inductive electrical motors producing an oscillating pressure in a gas. The main disadvantage of these conventional compressors is their limited lifetime, caused by mechanical friction and wear. Wear products degrade the cryocooler’s performance. Additional disadvantages are heat generation, induced vibrations and noise. This invention replaces the conventional electro-mechanical compressor by a device activated by piezoelectric elements (PZT stacks), which are frictionless, have a high volumetric power density and an extremely long lifetime, offering superior efficiency and reliability. The high efficiency together with a no-moving-parts design can make a piezo compressor a good alternative to the conventional, for applications requiring long life and reliability.
Direct quasistatic PZT actuation is extremely inefficient, as about 90% of the charge is wasted, perdominantly on the elasticity of the PZT ceramics itself. In order for the actuator to operate efficiently in resonance it must fit the working frequency of the cryocooler. Therefore, the compressor’s mechanism must reduce the resonance frequency by two orders of magnitude. To achieve this reduction in the resonance frequency this invention employs a stroke amplification system for the PZT actuator, and, in parallel, increases the mass of the compressing piston by adding the mass of the PZT ceramics and the PZT housing.
- Technology Benefits
- Linear piezo compressors are more energy-efficient, quieter and produce less heat and vibration than conventional rotary reciprocating compressors
- Technology Application
- Materials research
- ID No.
For more information, please click Here