Method and device for introducing a fluid into an exhaust-gas purificat ion system

Abstract From the Canadian patent

Method and device for introducing liquid into an exhaust-gas purification system, The nitrogen oxides emitted by an internal-combustion engine operated with excess of air are normally converted by the method of selective catalytic reduction (SCR) by bringing the nitrogen oxides together, with ammonia, into contact with a selective catalyst. In a motor vehicle, because of the dangers associated with the use of ammonia, ammonia should be carried only in the form of a substance which liberates ammonia generally an, aqueous urea solution. The problem solved by the invention consists in avoiding frost damage to sections of the exhaust-gas purification system during shutdown times and in making …