A kind of scr aftertreatment heating system and its control method

Abstract

The invention provides an SCR aftertreatment heating system and a control method thereof. The power supply ground ends of a pressure pipe relay, a liquid return pipe relay, a pipette relay and a urea pump relay in the aftertreatment heating system are connected with an ECU and are controlled through the ECU. When the SCR aftertreatment heating system has no failure and is in a urea heating mode, the voltage of the power supply ground ends of the four relays is controlled through the ECU to be zero, so that the relays achieve operation normally and normal heating is achieved. When the SCR aftertreatment heating system has a failure and is in a urea heating mode, the voltage difference between the power supply source ends and the power supply ground ends of the four relays is controlled to be zero, so that the four relays do not work normally, in other words, normal heating cannot be achieved, accordingly, the urea heating system is prevented from carrying out heating, and the problems that a resistive heater is too hot, a urea pump is damaged, and a pipeline is aged are prevented.

Description

technical field [0001] The invention relates to the technical field of automation, in particular to an SCR post-treatment heating system and a control method thereof. Background technique [0002] As a kind of power machinery, diesel engine has made outstanding contributions to the development of society, but it also causes environmental pollution. It is becoming more and more difficult to achieve emission standards simply by improving engine technology. In this case, the SCR system is introduced. The basic working principle of the SCR (Selective Catalytic Reduction) system: the exhaust gas of the engine flows out from the turbocharger After entering the exhaust pipe, the urea injection unit installed on the exhaust pipe sprays a certain amount of urea aqueous solution into the exhaust pipe in the form of mist. The urea droplets undergo hydrolysis and pyrolysis reactions under the action of high-temperature exhaust gas, forming The required reducing agent ammonia (NH 3 ), ...

AI Technical Summary

Problems solved by technology

[0004] When the relay that heats urea is stuck or short-circuited, although the fault monitoring unit in the SCR system can detect such faults, it cannot stop the urea heating function, so the urea heating unit will continue to heat, resulting in overheating of the heating resistance wire, urea The pump is damaged and the pipeline is aging. In severe cases, the urea pipeline will spontaneously ignite, affecting the safety of vehicles and drivers.

[0005] In order to overcome this defect, the present invention provides a circuit structure that can prevent the urea heating unit from heating when the circuit fails, preventing the problems of overheating of the heating resistance wire, damage of the urea pump, and aging of the pipeline

Images