| 摘要 |
<p>PURPOSE: To stably judge plugging of an exhaust gas purifying device by calculating a pressure ratio between an exhaust pressure on the upstream side of the exhaust gas purifying device and the exhaust pressure on the downstream side, and averaging the pressure ratio in sequence for a prescribed period. CONSTITUTION: An upstream side pressure and downstream side pressure of an exhaust gas purifying device 3 are read out by pressure sensors 4, 5, and a ratio between them is calculated for plugging detection. The pressure ratio data are average-processed in sequence, i.e., the successive average pressure ratio = (integrated value of pressure ratios in past several minutes + latest pressure ratio)/(number of pressure ratio data). Whether a engine revolving speed is low or not is judged. If the engine revolving speed is not low, the successive average pressure ratio is compared with a stored pressure ratio for an plugging quantity to be reproduced. If the successive average pressure is larger, a catalyst of the purifying device 3 is judged to have plugging. If the engine revolving speed is low, plugging judgment is stopped, and pressure ratio data are held as they are.</p> |
