Urea injection amount calculation method, double-SCR system, engine and electronic equipment

The invention belongs to the technical field of diesel engine aftertreatment systems, and particularly relates to a urea injection amount calculation method, a double-SCR system, an engine and electronic equipment. The calculation method comprises the steps that the preceding-stage SCR conversion efficiency of a preceding-stage SCR system is calculated according to the first urea injection amount and the first oxynitride content, an aging correction coefficient is obtained according to the first temperature, the first nitrogen dioxide content after DOC is calculated according to the preceding-stage SCR conversion efficiency and the aging correction coefficient, and the second nitrogen dioxide content after DOC is calculated according to the first nitrogen dioxide content. And calculating the second nitrogen dioxide content after passing through the DPF, calculating the ratio of nitric oxide to nitrogen dioxide in the second nitrogen oxide content, and calculating the second urea injection amount in front of t