Catalyst heating with exhaust back-pressure

摘要

Embodiments for controlling an exhaust back-pressure valve are provided. In one example, a method for operating an engine comprises closing an exhaust back-pressure valve in response to a component temperature, and adjusting intake and/or exhaust valve operation in response to closing the exhaust back-pressure valve to reduce cylinder internal exhaust gas recirculation (EGR). In this way, combustion stability may be maintained while the exhaust back-pressure valve is closed.

主权项

1. A system, comprising:
an engine including a variable camshaft timing system; a catalyst positioned in an exhaust of the engine; an exhaust back-pressure valve positioned downstream of the catalyst; and a controller including instructions to:
close the exhaust back-pressure valve when a temperature of the catalyst is below a threshold; andadjust the variable camshaft timing system to reduce intake and exhaust valve overlap responsive to the closing of the exhaust back-pressure valve.