Split cycle engine

A split cycle internal combustion engine, comprising:

• a combustion cylinder accommodating a combustion piston;
• a compression cylinder accommodating a compression piston and being arranged to provide compressed fluid to the combustion cylinder;
• and
• a controller arranged to receive an indication of a parameter associated with the combustion cylinder and/or a fluid associated therewith and to control an exhaust valve of the combustion cylinder in dependence on the indicated parameter to cause the exhaust valve to:
• close during a return stroke of the combustion piston, before the combustion piston has reached its top dead centre position, when the indicated temperature is less than a target temperature;
• and
• close on completion of the return stroke of the combustion piston, as the combustion piston reaches the top dead centre position, when the indicated temperature is equal to or greater than the target temperature.

A method of operating a split cycle internal combustion engine, the engine comprising:

• a combustion cylinder accommodating a combustion piston;
• and
• a compression cylinder accommodating a compression piston and being arranged to provide compressed fluid to the combustion cylinder;
• the method comprising:
• receiving an indication of a parameter associated with the combustion cylinder and/or a fluid associated therewith and;
• controlling an exhaust valve of the combustion cylinder in dependence in the indicated parameter to cause the exhaust valve to:
• close during a return stroke of the combustion piston, before the combustion piston has reached its top dead centre position, when the indicated parameter is less than a target value for the parameter;
• and
• close on completion of the return stroke of the combustion piston, as the combustion piston reaches the top dead centre position, when the indicated parameter is equal to or greater than the target value for the parameter.