Test method and device for simulating thermal WHTC circulation in diesel hot and cold WHTC circulation

Abstract

The invention discloses a test method and device for simulating thermal WHTC circulation in diesel hot and cold WHTC circulation. The test method comprises the following steps that test conditions aremet by controlling the lower air inlet temperature, air inlet vacuum degree, post-intercooling temperature and exhaust back pressure under rated conditions of a diesel engine according to rules; according to a WHTC circulation program set by a gantry, circulation conditions in the WHTC circulation program at the last 600+ / -10s are selected for testing to pre-process an SCR catalyst unit; after the SCR catalyst unit is preprocessed, diesel engine hot dipping is carried out immediately for 10+ / -1min to serve as pro-processing of a diesel engine hot start WHTC circulation test; the steps of a formal thermal WHTC circulation test involve that a gantry WHTC circulation program is started immediately after a hot dipping period is completed for the formal thermal WHTC circulation test, thereforethe temperature of a thermal WHTC circulation SCR catalytic unit is consistent with the temperature of the thermal WHTC circulation in the hot and cold WHTC circulation, the efficiency of the SCR catalyst unit can be fully utilized, the consumption of urea can be reduced, the energy is saved, the environment is protected, and a large amount of test time can be saved.

Description

technical field [0001] The invention relates to the field of vehicle diesel engine bench tests, in particular to a test method and device for simulating a hot WHTC cycle in a diesel engine cold and hot WHTC (transient test cycle) cycle. Background technique [0002] Existing national six-stage emission regulations for diesel and diesel engines for vehicles all need to meet the cold and hot WHTC emission limits. The conversion efficiency of substances is very sensitive to temperature, especially in the low temperature stage. For the calibration of the hot and cold WHTC tail row, in order to improve the development efficiency, the pure hot WHTC is generally calibrated. Entering the hot WHTC test cycle at different catalyst temperatures will cause the SCR catalytic unit in the hot WHTC test cycle. The temperature distribution is also different. If the temperature distribution in the catalytic converter of the hot WHTC cycle in the actual cold and hot WHTC cycle cannot be simul...

AI Technical Summary

Problems solved by technology

For the calibration of the hot and cold WHTC tail row, in order to improve the development efficiency, the pure hot WHTC is generally calibrated. Entering the hot WHTC test cycle at different catalyst temperatures will cause the SCR catalytic unit in the hot WHTC test cycle. The temperature distribution is also different. If the temperature distribution in the catalytic converter of the hot WHTC cycle in the actual cold and hot WHTC cycle cannot be simulated faithfully, the calibrated urea injection amount will increase during calibration, and the final result of the cold and hot WHTC will be smaller , large leakage of guide ammonia, etc., or cause the calibrated urea injection volume to decrease during calibration, and finally the results of hot and cold WHTC are not up to standard

[0003] In order to solve the above problems, the cold and hot WHTC calibration of diesel engines can accurately simulate the hot state entry conditions of the actual cold and hot WHTC cycle, so that the temperature of the SCR catalytic unit in the hot state WHTC cycle is consistent with the hot state cycle in the actual cold and hot WHTC cycle. The current general practice: First, according to the temperature of the inlet and outlet of the SCR catalytic unit when the hot state cycle enters the working condition in the actual cold and hot WHTC cycle, when the temperature of the inlet and outlet of the SCR catalytic unit is close to this temperature, start the program to verify the pure hot state WHTC According to this method, it is also possible to make the temperature of the SCR catalytic unit in the purely hot WHTC cycle and the hot cycle in the actual hot and cold WHTC cycle also relatively similar, but due to the inconsistent working conditions of the heat engine or the inconsistency of the heat engine mode, the temperature distribution of the SCR internal carrier is still relatively different. A large difference will also affect the catalytic efficiency of the catalytic unit, resulting in inaccurate results of cold and hot WHTC emissions. Once, it is a waste of time and resources

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