System for controlling the temperature of a cylinder wall in an engine

A system for controlling a temperature of a cylinder wall in an engine, comprising:

• an upper water jacket facing a portion of a cylinder wall on which a piston is slidably guided, where said upper water jacket is adjacent to a top dead center of the piston;
• a lower water jacket facing another portion of said cylinder wall, which is adjacent to a bottom dead center of the piston;
• an upper cylinder portion temperature detecting means for detecting a temperature of an upper portion of said cylinder wall adjacent to the top dead center of the piston;
• a lower cylinder portion temperature detecting means for detecting a temperature of a lower portion of the cylinder wall adjacent to the bottom dead center of the piston;
• an upper cooling circuit for controlling cooling water flowing through said upper water jacket to converge the temperature of the upper portion of the cylinder wall detected by said upper cylinder wall temperature detecting means to a target temperature for the upper portion of the cylinder wall;
• and
• a lower cooling circuit for controlling the cooling water flowing through said lower water jacket to converge the temperature of the lower portion of the cylinder wall detected by said lower cylinder wall temperature detecting means to a target temperature for the lower portion of the cylinder wall.

A system for controlling a temperature of a cylinder wall of each of a plurality of cylinders in a multi-cylinder engine, comprising:

• an upper water jacket facing a portion of a cylinder wall on which a piston is slidably guided, where said upper water jacket is adjacent to a top dead center of the piston;
• and
• a lower water jacket facing another portion of said cylinder wall adjacent to a bottom dead center of the piston;
• wherein cooling water exiting the a radiator is passed through said upper water jacket and then through said lower water jacket back to said radiator, and wherein the cooling water passing through said upper water jacket is supplied to a lower end of said lower water jacket through respective branch passages of a gallery which correspond to said plurality of cylinders.