Reducing agent spraying and metering device

Abstract

The invention discloses a reducing agent spraying and metering device, which comprises a reducing agent storing box, a supply pump, a metering valve, a mixing cavity, an atomizing nozzle, a controller, a switching valve and a low-pressure air pump, wherein a reducing agent of the reducing agent storing box is mixed in the mixing cavity through the supply pump and the metering valve, is then atomized through the atomizing nozzle, is sprayed into an exhaust pipe, is mixed with waste gas, and is reduced and purified; the low-pressure air pump is used for supplying pressure air to the mixing cavity during working of an engine, and sweeping the reducing agent in the supply pump and a pipeline behind the supply pump back into the reducing agent storing box when the engine stops working; and the switching valve is used for controlling and switching the reducing agent storing box to supply the reducing agent and pressure gas of the low-pressure air pump to sweep the supply pump and the pipeline behind the supply pump. An independent air source is adopted, so that the pressure is stable and does not fluctuate along with the change of the working condition of the engine, automobile compressed air is not consumed, and the potential safety hazard of compressed air leakage is eliminated. A cleaning method of the spraying and metering device is simple, and a complete effect is achieved.

Description

technical field [0001] The present invention relates to a reductant injection metering device for mixing liquid reductant into an exhaust gas flow. Background technique [0002] With the increasingly severe environmental problems and energy crisis and stricter emission regulations, more and more energy-saving and emission-reduction technologies are applied to vehicles, among which SCR (Selective Catalytic Reduction) technology is a method to reduce nitrogen oxide emissions , SCR technology is to spray urea solution, a reducing agent, into the exhaust flow of the engine to release ammonia gas, which reacts with nitrogen oxides in the exhaust gas in the SCR catalytic converter to form nitrogen and water, thereby achieving Purification purpose. Urea solution, a reducing agent, will cause crystallization when in contact with air. The injection metering device needs to be emptied after use to avoid blockage of the internal channel of the device. [0003] At present, the SCR sys...

AI Technical Summary

Problems solved by technology

The emptying of the residual urea solution in the non-air-assisted urea injection device is realized by switching the hydraulic pipeline, and the system is relatively complicated. Please refer to the patent DE102006033027

The air-assisted urea injection metering device uses automobile compressed air to clean the pipeline after the mixing chamber. For details, please refer to the patent CN100587263C. The defect of this method is that it consumes automobile compressed air, which has potential safety hazards, and the cleaning is not complete.

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