Reduction of friction in a piston-cylinder assembly for cryogenic refrigerator

Prof. Izhak Etsion | Mechanical Engineering


Physics and Electro-Optics | Sustainability and Energy

The Technology

The need for a small, low-power, reliable and inexpensive cryogenic refrigerator is increasing, especially for application in widely distributed IR systems such as binoculars, sights, military and civilian drones, applications to the automotive world such as autonomous vehicle cameras. Friction in this assembly is a major design factor in terms of lower power consumption and lower cost, and higher reliability and longevity. The need to reduce friction in the piston-cylinder assembly is critical to the performance of the refrigerator. In a cryogenic refrigerator, the design conditions are more difficult because lubricants cannot be used, the environment is compressed with helium gas, and the required level of accuracy is of a diameter range of 10 microns. For these reasons, high-level centralization is required. The developed technology focuses on friction reduction by defining a piston profile in favor of piston-cylinder centering in the presence of helium gas. The developed technology is design that realizes a center with maximum radial rigidity, that is, creates a situation in which a deviation from the center state will provoke forces that will return the piston to a state of center. To do this, build the geometry, i.e. the profile of the piston, so that hydrodynamic and hydrostatic forces appear when the piston moves from the center. The end result is -no contact between the piston and the cylinder, a situation that allows frictional forces to be reduced in a state of relative motion between them.


  • Combination of a simple design and manufacturing solution will address the need to reduce friction in the assembly, leading to lower power consumption and lower cost, and higher reliability and longevity

Applications and Opportunities

  • Cryogenic refrigerators
arrow Business Development Contacts
Shikma Litmanovitz
Director of Business Development, Physical Science