| 摘要 |
<p>PURPOSE:To detect a pressure loss value of a filter accurately by discontinuing particulate collection at an appropriate time, and detecting the pressure loss value of the filter by means of a constant volume of gas supply without recourse to the operating condition at that time. CONSTITUTION:In the case of operating an engine, in a control circuit 5, the judgment is made by observing on whether or not it is a predetermined particulate collection volume measuring time, for example, on whether or not a timer counter is more than a prescribed value, and in the case of YES, signals to open the first-the third switching valves 11, 15 and 17 are outputted to respective actuators 11, 18 and 19. Furthermore, approximately in synchronism with these, an air pump 13 is driven, and a constant flow rate of air is flown toward a filter 1 from the air pump 13. Under this constant flow rate of air supply condition, in order to detect pressures Pf and Pr in front and in rear of the filter 1, output signals of pressure sensors 8 and 9 are taken in so that a pressure loss value (Pf-Pr) can be found from the obtained pressure values Pf and Pr. Next, the present particulate volume (w) can be obtained by carrying out an operation based on this pressure loss value.</p> |
