Nowadays design and production of carburetor can not make the mixture of carburetor fit in with the ideal value of A/F ratio on all running conditions,the method of using micro-processor control A/F ratio can solve this problem.In this paper,the self-tuning and adaptive control method was used to realize the optimal control for A/F ratio.Based on the open-loop control,this method was combined with the close-loop control.
The adaptive control method of using difference of slope change at the lowest specific fuel consumption point on fuel adjustment curve has wide adaptive ability.It is superior to the open-loop control,and does not need to use expensive exhaust gas oxygen sensor and other detect sensors compared with other close-loop control.The method that uses the rate of speed change to add air perturbation as feed-back singal is easy to use practically.
By the test on engine test stand,the method of using micro-processor being compared with original engine (EQ-6100Q engine),which has been carefully adjusted,the results show that this A/F ratio control method can decrease HC emission about 30%,CO emission about 40%,specific fuel consumption about 10%.
The control system does not need to measure the A/F ratio,but it has enough control accuracy and be put conveniently into practical use.