Exhaust gas cleaning device for diesel engines

An exhaust particulate cleaning device for a diesel engine comprising:

• a main passageway for exhaust gas having uniformly sized upstream and downstream portions and a middle portion between and narrower than the upstream and downstream portions;
• a trap case provided in the middle portion of the main passageway;
• a filter material disposed in the trap case for catching within the filter material particulates contained in the exhaust gas when the exhaust gas passes through the filter material;
• a heater means disposed at an upstream end of the filter material for igniting and burning the exhaust particulates trapped in the filter material;
• a bypass passage for the exhaust gas which bypasses the trap case and extends between the upstream and downstream portions of the main passageway, the bypass passage having an inner diameter the same size as the upstream and downstream portions of the main passageway and extending along a line of smooth flow of the exhaust gas discharged from the engine;
• a control valve means in the bypass passage for opening and closing the bypass passage;
• a signal means for generating a signal indicating commencement of ignition of the exhaust particulates in the filter material;
• a control means responsive to the signal to open the control valve means for a predetermined short period following receipt of the signal to allow a substantial amount of the exhaust gas to pass through the bypass passage during burning of said exhaust particulates, and for closing the control valve at the end of the short period to allow said exhaust gas to pass through the filter material.