随着全球经济的稳步发展，环境问题、特别是大气环境污染问题，已引起世界各国特别是大气污染严重的发达国家的普遍关注。目前，由于汽车排放是造成各国大气污染的主要原因．所以，控制汽车排放就成为保护大气环境的关键。 由于汽车给人类的生产和生活带来了无比的方便，人类的 With the steady development of the global economy, environmental issues, especially atmospheric pollution, have caused widespread concern among all countries in the world, especially developed countries with serious air pollution. At present, emissions from vehicles are the main cause of air pollution in various countries. Therefore, the control of vehicle emissions has become the key to protecting the atmosphere. Because of the car to human production and life has brought incomparable convenience to humanity