Patent ID: 7832370

Claim:
An apparatus for operating an internal combustion engine in low-load homogeneous charge compression ignition operation, comprising: a variable volume combustion chamber defined by a piston reciprocating within a cylinder between top-dead center and bottom-dead center points; an intake valve and an exhaust valve, a valve actuation device for varying phasing of said intake and exhaust valves, wherein said intake and exhaust valves are controlled by said valve activation device during repetitive, sequential exhaust, intake, compression and expansion strokes of said piston, said exhaust valve closing prior to said intake valve opening to create a negative valve overlap, said negative valve overlap being shorter for higher low-load operation and longer for lower low-load operation; a fuel injector injecting fuel into said combustion chamber during said negative valve overlap; and a heat source positioned to ignite said fuel during said negative valve overlap.