A gas-assisted metering injection system and its control method

Abstract

The invention relates to a gas-assisted type metered injection system and a control method thereof. The system comprises a metering pump, a double-fluid nozzle, a reducing agent storage device, a compressed air source and an aftertreatment controller. A reducing agent passageway and a compressed air passageway which are independent from each other are arranged in the metering pump. An inlet of the reducing agent passageway is connected with the reducing agent storage device, an inlet of the compressed air passageway is connected with the compressed air source, and an outlet of the reducing agent passageway and an outlet of the compressed air passageway are correspondingly connected with a liquid channel and a gas channel of the double-fluid nozzle. A liquid regulating mechanism is arranged in the reducing agent passageway, and a gas regulating mechanism is arranged in the compressed air passageway. The liquid regulating mechanism and the gas regulating mechanism are electrically connected with the aftertreatment controller. A liquid and gas mixing cavity is not contained in the metering pump, the risk that a reducing agent is likely to be crystallized in a gas-liquid mixing state is greatly avoided, and the reducing agent injection atomization effect and the injection precision are improved.

Description

technical field [0001] The invention relates to a vehicle SCR post-processing system and a control method thereof, in particular to a gas-assisted metering injection system and a control method thereof. Background technique [0002] Selective Catalytic Reduction (SCR) technology was first proposed by Americans in the 1950s, developed and applied in Japan in the 1970s, and industrialized in 1978. Due to the high efficiency of this method, the removal of NO X The capacity can reach more than 90%, and it is widely used in the NO of motor vehicles all over the world. X emission control. Harmful gases emitted by diesel engines contain nitrogen oxides (NO X ), using urea solution as a reducing agent in the SCR aftertreatment system to remove nitrogen oxides (NO X ), so as to meet the requirements of the corresponding national emission regulations. The working principle of the system is: the exhaust gas enters the exhaust pipe, and a urea nozzle is installed on the exhaust pip...

AI Technical Summary

Problems solved by technology

It is well known that the urea metering pump device is the core component of the SCR post-treatment system. The key technology is the control of the injection accuracy and spray effect of the urea solution. The injection accuracy and atomization effect of the urea solution are the key to ensuring the conversion efficiency of the catalyst. In the prior art, compressed air and urea solution are mixed and atomized in the urea metering pump, which will make the urea solution easy to crystallize in the gas-liquid mixed state, thereby reducing the spray atomization effect and spray accuracy of the urea solution

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