Patent ID: 8863505

Claim:
A catalyst heating system comprising: a first electronic circuit configured to receive a first signal from a first sensor and a second signal from a second sensor, wherein the first signal is indicative of a first temperature of a first catalyst in a catalytic converter of a catalyst assembly in an exhaust system of an engine, wherein the second signal is indicative of a second temperature of a second catalyst in the catalytic converter, wherein the first catalyst is an electrically heated catalyst (EHC), and wherein the second catalyst is not electrically heated and is downstream from the first catalyst; a second electronic circuit configured to select operation in a plurality of modes including selecting operation in an EHC heating mode, a fuel enrichment mode, and a secondary air injection mode based on the first temperature and the second temperature; and a third electronic circuit configured to (i) control current to the first catalyst based on the selected plurality of modes, (ii) operate in the EHC heating mode in response to the first temperature being less than a first predetermined temperature and the second temperature being less than a second predetermined temperature, (iii) refrain from operating in the secondary air injection mode while the first temperature is greater than a catalyst light off temperature and the second temperature is less than the second predetermined temperature to prevent additional air flow generated during the secondary air injection mode from cooling down the second catalyst, and (iv) in response to the second temperature of the second catalyst being greater than the second predetermined temperature, operating in the fuel enrichment mode while operating in the secondary air injection mode to increase the second temperature to a third predetermined temperature.