Importance

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Abstract

A temperature control apparatus for at least two catalytic converters which are connected in series in an exhaust passage of an internal combustion engine mounted on a vehicle. A by-pass is disposed in parallel with a first catalytic converter which is connected in the vicinity of the engine. Valve drive means serves to drive a control valve for controlling the ratio between the amounts of exhaust gas introduced into the first catalytic converter and the by-pass. Control means serves to calculate the deviation between a reference value and a temperature value, which is associated with the catalyst-bed temperature of the first catalytic converter, and is detected by temperature detecting means, and to deliver a drive signal to the valve drive means in accordance with the deviation, thereby controlling the opening of the control valve. Immediately after the start of the engine, therefore, the catalyst-bed temperature of the first catalytic converter rises to the reference temperature value for an optimum purifying efficiency. Thereafter, the bed temperature is kept constantly in the vicinity of the reference value.

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First Claim