Mechanical pump type SCR urea spraying system

Abstract

The invention relates to a mechanical pump type SCR urea spraying system, consisting of a urea tank, a urea tank switch valve, a filter, a urea pump, an energy accumulator, a urea nozzle, a heat exchanger, a pressure regulating valve, a cooling device, and an electronic control unit. The system is characterized in that the urea pump is a mechanical pump, and the driving wheel of a diesel engine drives the transmission shaft of the urea pump through a pulley. A urea cooling device consists of the cooling device, a temperature control valve, a refrigerant inlet pipe and a refrigerant outlet pipe. The urea cooling device is arranged between the pressure regulating valve and the switch valve of the main pipeline. The energy accumulator is arranged on the pipeline between the outlet of the urea nozzle and the pressure regulating valve. The refrigerant inlet pipe of the urea cooling device is connected with the high pressure pipe of the automotive air conditioning, the refrigerant outlet pipe is connected with the low pressure pipe of the air conditioning, and the flow direction of the refrigerant fluid is opposite to the flow direction of the urea solution. The system of the invention reduces the energy consumption, and the flow rate of the urea solution is regulated in real time according to the engine speed, thereby avoiding the waste of the energy. The mechanical pump also has the advantages of low cost, long service life and is convenient to maintain.

Description

technical field [0001] The present invention relates to a kind of mechanical pump type SCR urea injection system, is used for the SCR urea injection system of diesel engine exhaust aftertreatment, relates to a kind of Selective Catalyst Reduction system (Selective Catalyst Reduction) for reducing diesel engine NOx emission more specifically ), which belongs to the exhaust gas purification system of the internal combustion engine. Background technique [0002] For the emissions of motor vehicles, people use various methods to eliminate the harmful substances contained in them. SCR technology is to reduce diesel engine NO X A very effective method of emission. The engine SCR post-treatment technology is to spray the reducing agent urea solution into the engine exhaust. Under the action of the exhaust gas temperature and air flow, the urea can quickly decompose and release ammonia, and the NO X Reduced to nitrogen to reduce NO X Effect. Urea aqueous solution has been popul...

AI Technical Summary

Problems solved by technology

[0004] A common feature of these technical solutions is the use of DC electric pumps to pressurize the urea solution, which consumes the electric energy of the vehicle due to the need for battery power.

The electric energy on the car is generated by the engine. After the conversion of mechanical energy-electric energy-mechanical energy, there must be some losses. The use of an adjustable electric pump requires an additional control system, while the use of a fixed-speed electric pump means that the electric pump is always at full load. state, the flow cannot be adjusted timely according to the engine speed, and the energy consumption is relatively high

[0005] The urea solution system with direct injection is used, and the urea nozzle is directly installed on the mixer of the exhaust pipe. If the exhaust temperature of the engine is too high, the urea nozzle will be damaged, and the urea solution must be cooled. The disclosed technology uses urea solution for cooling Urea nozzle, after the urea solution exchanges heat with the nozzle and the exhaust pipe, the temperature rises, which affects the accuracy of injection metering, and the urea solution needs to be cooled

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