METHOD AND APPARATUS FOR DETECTING AMOUNT OF PARTICLE MATERIAL TRAPPED IN EXHAUST GAS FILTER IN DIESEL ENGINE

摘要

PURPOSE: To obtain a relatively simple circuit with high accuracy by providing means for comparing the strengths of the transmitting microwave, transmitted microwave and reflection wave and detecting the difference therebetween. ;CONSTITUTION: Exhaust gas from an engine is trapped by a particle filter 16. A microwave transmitting antenna 20 and a receiving antenna 30 are arranged in the particle filter 16. A reflection ratio meter 24 has three outputs. One is a reference signal V_ref and another one is a supply microwave signal V_i, the rest output is a signal V_r indicating the strength of the reflection component of the microwave signal. A signal detector 60 generates a receiving signal V_out indicating the strength of the microwave signal at the receiving side. The reference signal V_ref, the reflection signal V_r and the receiving signal V_out are inputted to a comparator 70 to determine a signal V_d corresponding to the transmission loss i.e., the dielectric loss ratio of the filter 16. It is possible to determine the combustion time of soot in the particle filter by monitoring the output value of the comparator 70.;COPYRIGHT: (C)1993,JPO