System for measuring particulate discharge from vehicular internal combustion engine

In a system for measuring the quantity of particulates contained in exhaust gases from an internal combustion engine, comprising a mixing section in which the engine exhaust gases are mixed with and diluted by a large amount of clean air, a blower means for sucking the engine exhaust gases and the clean air into said mixing section and discharging the mixed and diluted gases therefrom, gas sampling means for sampling a part of the flow of the diluted gases, said gas sampling means including a sampled gas line for the flow of the sampled gases, a sampling probe through which the sampled gases flow into said sampled gas line, a sampling pump disposed in said sampled gas line for sucking the sampled gases into said line and discharging the sampled gases therefrom, filter means disposed in said line between said probe and said sampling pump for collecting the particulates contained in the sampled gases, the improvement which comprises means for detecting the pressure drop across said particulate collecting filter means and converting the detected pressure drop into an electric signal, and a particulate discharge operation means operative to compute the quantity of particulate content of the engine exhaust gases on the basis of the time differential of said electric signal.