Temperature control apparatus for vehicular catalytic converters

Claim 1

A temperature control apparatus for at least two catalytic converters connected in series in a exhaust passage of an internal combustion engine mounted on a vehicle, a first of said at least two catalytic converters being connected in the vicinity of said engine, and a second of said at least two catalytic converters being connected farther from said engine than said first catalytic converter, the control apparatus comprising: a by-pass connected in parallel with said first catalytic converter; a control valve for substantially continuously and variably controlling the ratio between the amounts of exhaust gas introduced from said engine into said first catalytic converter and into said by-pass; valve drive means for driving said control valve in a substantially continuous manner; temperature detecting means for detecting a temperature value associated with the catalyst-bed temperature of said first catalytic converter; and control means for calculating a deviation between a reference value and the temperature value detected by said temperature detecting means, and for delivering a drive signal to said valve drive means in accordance with said deviation, thereby controlling the opening of said control valve to keep said temperature value associated with said catalyst-bed temperature of said first catalytic converter in the vicinity of said reference value.