Development Of Universal Exhaust Gas Oxygen Sensor Interface Controller

With the wide applying of lean combustion technology, traditional switch type EGO has not satisfied the request of AFR close loop control in lean burning engine. The switch type EGO has been replaced by the UEGO. UEGO can offer more precise and wide feedback AFR signals to engine ECU, instead lean or rich signals from switch type EGO.UEGO belongs to ZrO₂ sensor, which is made up of Nernst cell and pump cell. In another word, UEGO is made up of EGO and a pump oxygen cell. UEGO plays an big role in lean burning engine. UEGO makes AFR controlled in material values. Due to the pump circuit and temperature of UEGO must be controlled, an electronic controller is used of controlling UEGO. Some controllers are integrated in engine ECU, and the other is separate. A separate UEGO controller is designed in this paper.In this paper, the UEGO interface controller is designed, including hardware circuit and system software. The hardware circuit is made up of microcontroller module, UEGO integrate circuit module, LCD module, power circuit and serial communication interface circuit and so on. After finishing hardware circuit, developing main program and sub program with C computer language. In the end, the function of UEGO interface controller is realized.In the process of writing this paper, first, based on the theory of the UEGO, microcontroller and sensor integrate circuit module, the hardware circuit of control unit has been designed. The reliability of the hardware circuit has been examined through the imitation and check to the circuit board. Later, the control system software has been designed, and finishing signal collection and LCD display from the UEGO. Finally, the control unit has been tested in engine frame. The test results show the control unit can collect feedback signals from UEGO, and display synchronously in LCD. At last, the control system is feasible.