| 摘要 |
<p>PURPOSE:To reduce the dimension of a semiconductor switching element and reduce cost by cooling the element by the air flowing through an air flow passage. CONSTITUTION:A filter 5 for collecting particulates is installed in the exhaust system of a diesel engine 1. An electric heater 6 is installed at the upstream side end part of the filter 5. A motor-driven air pump 9 supplies the secondary air to the filter 5. Midway in the electric power source circuit of the electric heater 6, a bipolar transistor 12 is arranged. Midway in the electric power source circuit of the motor-driven type air pump 9, a bipolar type transistor 13 is arranged. An ECU 16 controls the transistor 12, and puts the electric heater 6 into an electric conduction state, and controls the transistor 13, and drives the motor-driven type air pump 9. In this case, the transistors 12 and 13 are arranged in the air flow passage of the motor-driven type air pump 9, and the transistors 12 and 13 are cooled by the air which passes through the air flow passages.</p> |
