Anti-blocking device of air orifice in scr injection system

Abstract

The invention discloses an anti-blocking device for an air orifice in a SCR (Selective Catalytic Reduction) injection system. The air orifice is designed on a side wall of a mixing cavity on a pump body of a metering pump; the anti-blocking device comprises a cylinder cavity and a moveable component; the cylinder cavity is formed on the pump body; the moveable component is arranged in the cylinder cavity; the cylinder cavity is divided into a first cavity and a second cavity by the moveable component; a spring and a breathing hole which are connected with the moveable component are arranged in the first cavity; a compressed air inlet is arranged in the second cavity; a through needle is arranged at the tail end of a cylinder component in the second cavity; and the second cavity is communicated with the mixing cavity through the air orifice. The anti-blocking device provided by the invention can effectively prevent the air orifice from being reduced or blocked by the reducing agent crystals accumulated in the air orifice, so that the atomizing effect of the reducing agent is ensured.

Description

technical field [0001] The invention relates to an SCR system in the aftertreatment of diesel vehicle exhaust, in particular to an anti-blocking device for an air throttle hole on the side wall of a mixing chamber in a metering pump of the SCR system. Background technique [0002] With the continuous improvement of motor vehicle emission standards, vehicle exhaust purification systems have increasingly attracted the attention of motor vehicle manufacturers, and various technical routes have gradually matured. It is now known that reducing nitrogen oxides in the exhaust of internal combustion engines, especially diesel engines, through selective catalytic reduction (SCR) technology is a common technical route, that is, the reducing agent (32.5% urea aqueous solution) is atomized and quantitatively injected into the exhaust gas pipeline, and through the SCR catalyst, the main harmful gas NO in the exhaust gas X It is converted into nitrogen and water and discharged to achieve...

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Problems solved by technology

[0005] However, because the air throttling hole is small, its diameter is generally only about 0.7mm, so it is easy to be blocked by crystallized urea during the working process, resulting in a smaller air flow rate, affecting the atomization effect, and causing air throttling in severe cases If the hole is blocked, the air flow cannot enter the mixing chamber for gas-liquid agitation, and the spray effect is not obvious, thus affecting the catalytic reduction reaction of the reducing agent, and the ideal emission reduction effect cannot be achieved.

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