Analyses of heat conduction within combustion chambers in engine blocks

摘要

The presence of either grey iron or hypereutectic aluminium liners cast in engine blocks affects their heat conduction. A procedure to evaluate the phenomenon taking place in engine blocks with either type of liners was established by the insertion of thermocouples within the alloy of which the block is made of and into the liner; one-dimensional heat flow conditions were established by means of an electric heater located within the cylinder bore and forced air-cooling at the engine block side. The existence of a difference in temperature at the block-liner interface, which reflects the characteristics of the interface, was found; the values of this difference in temperature are in most cases below 5℃, although it was much higher in liners that had an isolating coating. The difference in temperature is minimised when clean hypereutectic aluminium liners are used, due to the establishment of a well-developed metallurgical joint.