EXHAUST EMISSION CONTROL DEVICE
First Claim
1. An exhaust emission control device comprising a particulate filter incorporated in an exhaust pipe for capturing particulates in exhaust gas, selective reduction catalyst arranged in parallel with and downstream of said particulate filter for selectively reacting NOx with ammonia even in the presence of oxygen, an S-shaped communication passage for introduction of the exhaust gas from a rear end of the particulate filter to a front end of the adjacent selective reduction catalyst in a forward fold-back manner and urea water addition means arranged midway of said communication passage for addition of urea water, wherein an upstream portion of said communication passage comprises a gas gathering chamber for encompassing the rear end of the particulate filter to gather the exhaust gas discharged from the rear end of the particulate filter through substantially perpendicular turnabout of the exhaust gas and a mixing pipe for extracting forward the exhaust gas gathered by the gathering chamber, openings formed in circumferentially spaced positions on a rear end of said mixing pipe for introduction of the exhaust gas, a downstream end of said gathering chamber being connected to the rear end of said mixing pipe such that said respective openings are encased and the rear end of said mixing pipe is closed.
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Accused Products
Abstract
An exhaust emission control device has a particulate filter 5 and a selective reduction catalyst 6 arranged side by side. An S-shaped communication passage 9 is arranged for introduction of exhaust gas 3 from a rear end of the filter 5 to a front end of the adjacent catalyst 6 in a forward fold-back manner and with a urea water addition injector 11 arranged midway of the passage 9. In order to satisfactorily disperse the urea water with enhanced mixing with the exhaust gas 3 even if the flow rate is increased, slits 12 are formed in circumferentially spaced positions on a rear end of a mixing pipe 9B constituting an upstream portion of the communication passage 9 so as to introduce the exhaust gas 3. A downstream end 9a of a gas gathering chamber 9A is connected to the rear end of the mixing pipe 9B such that the slits 12 are encased and the rear end of the mixing pipe 9B is closed.
92 Citations
10 Claims
- 1. An exhaust emission control device comprising a particulate filter incorporated in an exhaust pipe for capturing particulates in exhaust gas, selective reduction catalyst arranged in parallel with and downstream of said particulate filter for selectively reacting NOx with ammonia even in the presence of oxygen, an S-shaped communication passage for introduction of the exhaust gas from a rear end of the particulate filter to a front end of the adjacent selective reduction catalyst in a forward fold-back manner and urea water addition means arranged midway of said communication passage for addition of urea water, wherein an upstream portion of said communication passage comprises a gas gathering chamber for encompassing the rear end of the particulate filter to gather the exhaust gas discharged from the rear end of the particulate filter through substantially perpendicular turnabout of the exhaust gas and a mixing pipe for extracting forward the exhaust gas gathered by the gathering chamber, openings formed in circumferentially spaced positions on a rear end of said mixing pipe for introduction of the exhaust gas, a downstream end of said gathering chamber being connected to the rear end of said mixing pipe such that said respective openings are encased and the rear end of said mixing pipe is closed.
Specification