Engine exhaust temperature control device, motor vehicle and control method

Abstract

The embodiment of the invention provides an exhaust gas temperature control device for an engine, a motor vehicle and a control method. The exhaust gas temperature control device comprises an SCR (Selective Catalytic Reduction) box, a heat exchanger, a first exhaust pipe, a gas compressor, a reversing valve, a bypass pipe and an engine gas inlet pipe; the SCR box is connected with the heat exchanger; the first exhaust pipe is connected with the heat exchanger; gas exhausted from the SCR box enters the gas exchanger, is subjected to heat exchange and is then exhausted through the first exhaust pipe; the reversing valve is arranged in a pipeline, connected with the heat exchanger, of the gas compressor; one end of the bypass pipe is connected with the heat exchanger, and the other end of the bypass pipe is connected with the engine gas inlet pipe; when the exhaust gas temperature of the engine is lower than a threshold, the reversing valve enables the gas compressor and the heat exchanger to be communicated; air introduced by the gas compressor enters the heat exchanger through a pipeline, is subjected to heat exchange and then enters the engine gas inlet pipe through a by-pass pipe. According to the exhaust gas temperature control device, the motor vehicle and the control method provided by the invention, the exhaust gas temperature of the engine can be maintained at an appropriate temperature, the convention efficiency of chemical reactions in the SCR box is improved, and thus the exhaust gas of the engine can be purified and treated more thoroughly.

Description

technical field [0001] The invention relates to the technical field of engines, and more specifically relates to an engine exhaust temperature control device, a motor vehicle and a control method. Background technique [0002] At present, the engine exhaust gas is mainly purified through the SCR (Selective Catalytic Reduction Converter) system; the SCR system is a commonly used post-treatment system for nitrogen oxides, and a certain amount of Urea solution, urea solution is gasified at high temperature and decomposed into ammonia and water, ammonia and nitrogen oxides can remove most of the nitrogen oxides in the engine exhaust through the catalytic conversion reaction of the catalyst. [0003] It can be seen that the SCR system mainly relies on the chemical reaction in the SCR box to reduce NOx emissions. The conversion efficiency of this chemical reaction depends heavily on the reaction temperature, so there must be an appropriate temperature in the reaction process; if t...

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Problems solved by technology

[0003] It can be seen that the SCR system mainly relies on the chemical reaction in the SCR box to reduce NOx emissions. The conversion efficiency of this chemical reaction depends heavily on the reaction temperature, so there must be an appropriate temperature in the reaction process; if the reaction temperature is too high, the ammonia gas may spontaneously Combustion does not react with NOx, if the reaction temperature is too low, the reaction speed may be too slow, and the conversion efficiency of the chemical reaction is low

However, the exhaust temperature of the engine is different under different working conditions, which leads to low conversion efficiency of the chemical reaction in the SCR box and incomplete purification of engine exhaust under the condition of low engine exhaust temperature

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