Use of different pneumatic cylinder spring types in a variable displacement engine for engine and aftertreatment system temperature control

An engine controller for operating an internal combustion engine having a plurality of cylinders, the engine controller configured to:

• ascertain a cold start of the internal combustion engine;
• operate the internal combustion engine after the cold start such that some firing opportunities of the plurality of cylinders are fired while other firing opportunities of the plurality of cylinders are skipped;
• and
• for the firing opportunities that are skipped:
• (a) operate one or more of the plurality of cylinders as a first pneumatic cylinder spring until an aftertreatment system fluidly coupled to receive exhaust gases from the internal combustion engine has reached a threshold temperature;
• and
• (b) after the aftertreatment system has reached the threshold temperature, operate one or more of the plurality of cylinders as a second pneumatic cylinder spring until the internal combustion engine reaches a warm operating temperature,
• wherein the first pneumatic cylinder spring typo is different than the second pneumatic cylinder spring.

A method of operating a variable displacement internal combustion engine having a plurality of working chambers that operate on a working cycle, each working chamber having an intake valve and an exhaust valve that vents into an engine exhaust, the method comprising;

• ascertaining a temperature of an aftertreatment system fluidly connected to the internal combustion engine exhaust;
• operating the internal combustion engine at less than its full displacement so that some working cycles are skipped;
• and
• choosing a pneumatic cylinder spring for the skipped working cycles based at least in part on the temperature of the aftertreatment system.

A method of operating a variable displacement internal combustion engine having a plurality of working chambers in an engine block, each working chamber having an intake valve and an exhaust valve, comprising;

• ascertaining a temperature of the engine block;
• operating the internal combustion engine at less than its full displacement so that some of the working cycles are skipped;
• and
• choosing a pneumatic cylinder spring for the skipped working cycles based at least in part on the temperature of the engine block.