Method and device for cleaning an exhaust gas flow of a combustion engine

Abstract

The present invention relates to a method and a device for cleaning an exhaust flow of a combustion engine, wherein, the nitrogen oxide is removed from an exhaust flow by means of selective catalytic reduction (SCR), wherein, the exhaust flow is divided or branched to a main exhaust flow or an exhaust bypass at the upstream of at least one SCR catalyst for conveying the precursor substance of catalyst to the exhaust bypass. The precursor substance of the catalyst is converted to a reducing agent in a reactor. The reducing agent is conveyed out from the reactor by means of the exhaust bypass and is conveyed to the main exhaust flow at the upstream of the SCR catalyst device, wherein, the exhaust bypass is provided with an obstructing and / or throttling mechanism. According to the invention, at least one blocking and / or throttling mechanism is configured in the main exhaust flow. Furthermore the blocking and / or throttling mechanism is operated according to a preset reaction parameter at a state of limited idle speed and / or low-load operation, namely, the main exhaust flow is blocked or throttled definitively on one hand, and the exhaust bypass is blocked with a limited quality definitively.

Description

technical field [0001] The invention relates to a method according to the preamble of claim 1 for cleaning the exhaust gas flow of an internal combustion engine, in particular an exhaust gas supercharged internal combustion engine. The invention also relates to a device according to the preamble of claim 19 for cleaning the exhaust gas flow of an internal combustion engine, in particular an exhaust gas supercharged internal combustion engine. Background technique [0002] For exhaust gas purification, firstly the exhaust emissions from a cold start pose problems, since the legally prescribed exhaust emission limit values ​​must also be observed after a cold engine start and thus even when the catalytic converter has not yet reached operating temperature. Of great importance here is the so-called start-up temperature of the catalytic converter. The temperature at which the catalyst reached 50% conversion was indicated as the start-up temperature. Therefore, one of the objec...

AI Technical Summary

Problems solved by technology

However, it should be noted here that due to the thermodynamic NO / NO 2 The equilibrium is on the NO side, so the NO 2 The share in the total nitrogen oxides decreases with increasing temperature

Images