Exhaust purification filter

An exhaust purification filter, adapted to be arranged in an exhaust passage in an internal combustion engine, for trapping particulate matter contained in exhaust gas exhausted by the internal combustion engine, the exhaust purification filter comprising:

• alternately arranged exhaust gas inflow passages and exhaust gas outflow passages;
• porous partition walls which separate the alternately arranged exhaust gas inflow passages and exhaust gas outflow passages from each other, wherein a fine zone is defined at an upstream side of the partition walls and a rough zone is defined at a downstream side of the partition walls, and the rough zone is arranged downstream of the fine zone in a longitudinal direction of the exhaust gas inflow and outflow passages;
• and
• promoting members configured to promote the exhaust gas, which flows into the exhaust gas inflow passages, to pass through the partition walls in the fine zone and flow into the exhaust gas outflow passages, wherein
• the promoting members comprise porous coat layers in the fine zone,
• the fine zone, including the porous coat layers and the partition walls, is permeable to the exhaust gas,
• surfaces of the partition walls are covered by the porous coat layers in the fine zone, and are not covered by the porous coat layers in the rough zone,
• a median micropore diameter of the partition walls in the rough zone is set larger than a median micropore diameter of the partition walls in the fine zone, and is set so that ash contained in the exhaust gas is passable through the partition walls in the rough zone,
• the porous coat layers have a median micropore diameter smaller than the median micropore diameter of substrates of the partition walls, and
• the porous coat layers stick out from the surfaces of the partition walls, which face the exhaust gas inflow passages, inward of the exhaust gas inflow passages.

An exhaust purification filter, adapted to be arranged in an exhaust passage in an internal combustion engine, for trapping particulate matter contained in exhaust gas exhausted by the internal combustion engine, the exhaust purification filter comprising:

• alternately arranged exhaust gas inflow passages and exhaust gas outflow passages;
• porous partition walls which separate the alternately arranged exhaust gas inflow passages and exhaust gas outflow passages from each other, wherein a fine zone is defined at an upstream side of the partition walls and a rough zone is defined at a downstream side of the partition walls;
• and
• promoting members configured to promote the exhaust gas, which flows into the exhaust gas inflow passages, to pass through the partition walls in the fine zone and flow into the exhaust gas outflow passages, wherein
• the promoting members comprise porous coat layers in the fine zone,
• the fine zone, including the porous coat layers and the partition walls, is permeable to the exhaust gas,
• surfaces of the partition walls are covered by the porous coat layers in the fine zone, and are not covered by the porous coat layers in the rough zone,
• a median micropore diameter of the partition walls is set so that ash contained in the exhaust gas is passable through the partition walls in the rough zone,
• the porous coat layers have a median micropore diameter smaller than the median micropore diameter of the partition walls,
• the porous coat layers stick out from the surfaces of the partition walls, which face the exhaust gas inflow passages, inward of the exhaust gas inflow passages, and
• in the fine zone, the promoting members further comprise guide members configured to guide the exhaust gas in the exhaust gas inflow passages toward the partition walls,
• the guide members extending from the porous coat layers inward of the exhaust gas inflow passages and also toward inlets of the exhaust gas inflow passages.