CONTROL STRATEGY BASED ON FLOW CONSERVATION EQUATION
FOR HIGH-PRESSURE COMMON RAIL SYSTEM |
Zi-Guang Gao 1,2, Hong-Meng Li 1,2, Chun-Long Xu 3, Guo-Xiu Li 1,2, Min Wang 3 |
1School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University 2Ministry of Education, Beijing Jiaotong University 3China North Engine Research Institute |
|
|
|
|
ABSTRACT |
As the most advanced fuel injection system, the common rail system can achieve the flexible control of injection pressure, injection timing and injection rate. Thus, the pressure control strategy of high-pressure common rail system (HPCRS) will be critical for the performance of the diesel engine, as it affects its injection characteristics. In this paper, model in loop (MIL) simulation studies were carried out, a high-precision common rail hydraulic model and analytical rail pressure control strategy based on flow continuity equation were established. The delay of the high-pressure pump was accounted for and included in the proposed strategy, making it more targeted for HPCRS. The delay can be extremely important for high-pressure common rail overshoot especially in variable working condition. Next, the proposed strategy was compared to the traditional PI-based control strategy in both the start-up and transient conditions. Results indicated that the proposed strategy performs better regarding the overshoot, notably improving the control effect (compared to traditional PI-based strategy). The advances of using the proposed strategy primarily include improvements in working conditions with the obvious change in cycle injection quantity and engine speed. Both the proposed control strategy and PI-based strategy can track pressure effectively in various working conditions. |
Key Words:
High-pressure common rail system (HPCRS), Hydraulic simulation, Cycle injection fluctuation, Control strategy, Pressure fluctuation |
|