(under subclass 172) Apparatus in which the piston is provided with a sealed space in a portion thereof for the purpose of modifying the heat exchange properties of said piston portion.
(1) Note. The space may either be filled with a gas, or an insulating material, or may be under a vacuum.
SEE OR SEARCH CLASS
123, Internal-Combustion Engines,
41.16, for an internal combustion engine piston provided with
a closed space having a coolant material sealed in said space.
