A METHOD FOR REGENERATING A NOX ADSORBER CATALYST

摘要

A control (30) for controlling a variable valve actuation mechanism (26) of an internal combustion engine (10) to regenerate a NOx adsorber catalyst (35) i n the exhaust system (22) of the engine. The control comprises an operating program (50) for regenerating the catalyst while the engine is running under its own power by causing the variable valve actuation mechanism to change th e timing of operation of the intake valves (18) so as to transition the fuel-a ir ratio of mixture that is being combusted in the cylinders (16) from a relatively leaner mixture to a mixture that sufficiently richer than stoichiometric to effectively regenerate the catalyst.