Patent ID: 8683783
Filing Date: 2014-04-01
Classification: B01D,B01F,F01N,F02B

Abstract:
1. An exhaust purification apparatus for an internal combustion engine, the exhaust purification apparatus comprising: a catalytic device arranged in an exhaust passage of the engine to purify an exhaust gas from the engine with an additive; a venturi-shaped mixing chamber arranged in the exhaust passage upstream of the catalytic device, the mixing chamber including a diameter-reducing section having a diameter decreasing toward a downstream side, a constricted section continuously extending from the diameter-reducing section and having a minimum diameter, and a diameter-increasing section continuously extending from the constricted section and having a diameter increasing toward the downstream side; a swirl generator arranged in an upstream portion of the diameter-reducing section of the mixing chamber to generate a swirl flow of the exhaust gas; and an additive injection nozzle arranged near the swirl generation device, either on an upstream or downstream side of the swirl generator to inject the additive into the exhaust gas, wherein a distance “a” from the swirl generator to a point in the constricted section of the mixing chamber and a distance “b” from the point in the constricted section to an inlet of the catalytic device is set so that a ratio a/b falls within a setting range of from 0.5 to 1.0 to restrict ammonia slip from the catalytic device, and wherein at the setting range of the ratio a/b, the catalytic device shows exhaust purification efficiency equal to or higher than a predetermined value and also an amount of the ammonia slip from the catalytic device is equal to or smaller than a predetermined amount when at least one of the distance “a” or the distance “b” is varied under predetermined conditions.