Exhaust aftertreatment method
A technology of exhaust post-treatment and exhaust back pressure, which is applied in the direction of exhaust treatment, electronic control of exhaust treatment devices, diagnostic devices of exhaust treatment devices, etc., which can solve the problems of high cost of use and high fuel consumption of diesel vehicles , to achieve the effects of reducing fuel consumption and use cost, eliminating SCR crystallization, preventing and SCR crystallization
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Embodiment 1
[0033] combine figure 1 As shown, an exhaust aftertreatment method provided in an embodiment of the present invention includes the following steps:
[0034] S1. Detect the exhaust gas temperature, and execute step S2. Exhaust temperature is detected by a temperature sensor installed in the exhaust duct.
[0035] S2. Determine whether the exhaust gas temperature is lower than the first temperature threshold, if yes, perform step S3, otherwise, perform step S4. Wherein, the value range of the first temperature threshold is 300-400°C. Specifically, the first temperature threshold is taken as 350°C. When the exhaust gas temperature is lower than 350°C, the efficiency of SCR to convert nitrogen oxides will decrease, and at the same time, the urea solution injected by SCR into the engine exhaust pipe will undergo a series of other reactions and crystallize. In addition, the PM trapped inside the DPF is gradually increasing, which may block the DPF. At this time, it is necessary...
Embodiment 2
[0043] combine figure 2As shown, the exhaust post-treatment method of this embodiment is basically the same as that of Embodiment 1, and the same parts as Embodiment 1 will not be repeated in this embodiment. The difference is that step S4' is also included before step S4, Step S4' is: judging whether the exhaust gas temperature is lower than the second temperature threshold, if yes, execute step S4, otherwise, execute step S6; the second temperature threshold is greater than the first temperature threshold. Specifically, the second temperature threshold is 500°C. When the exhaust back pressure is not less than 20kpa, the engine increases the temperature by executing the Miller cycle. When the exhaust temperature rises above 500°C, if the engine continues to execute the Miller cycle, it will cause the engine to burn out. Therefore, when the exhaust gas temperature is not less than 500°C, the engine needs to stop the Miller cycle and start normal operation. When the exhaust...
Embodiment 3
[0046] combine image 3 The shown embodiment is basically the same as the exhaust aftertreatment method of embodiment 2, and the same part as embodiment 2 will not be repeated in this embodiment. After normal operation and before performing step S1, the following steps are also performed:
[0047] S8, DPF performs active regeneration, and then executes step S9
[0048] S9, judging whether the exhaust back pressure is less than the pressure threshold, if so, execute step S10, otherwise execute step S8;
[0049] S10. The DPF stops active regeneration, and executes step S1.
[0050] When the exhaust gas temperature is not less than 500°C, regardless of whether the blockage in the DPF and SCR is removed, in order to prevent the engine from burning out due to excessive temperature rise, the engine must immediately stop the Miller cycle and start normal operation. After the engine is running normally, the exhaust temperature will gradually drop. At this time, the exhaust temperat...
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