| 초록 |
Knock mitigation is the major challenge for the efficiency improvement of an SI engine. To investigate the knock phenomenon, it is important to measure the wall temperature because knock is mostly affected by the wall temperature of the combustion chamber. The measurement of the piston wall temperature is challenging, however, because the piston reciprocates at a very high speed during engine operation. In this study, the design procedure of the linkage system for piston temperature measurement is presented. First, the kinematics of the system was analyzed considering the practical engine application. To obtain the optimal design, a new optimization methodology was established with the modified Nelder-Mead algorithm. Thereafter, stress analysis was conducted to estimate the durability of the designed system under harsh operating conditions. As a result, the designed system was verified to have a safety factor of 2 under a 6000 rpm engine speed. The selected design was fabricated and retrofitted into the engine, and the piston wall temperature was successfully measured. It was found that the piston wall temperature was mainly affected by the liner wall temperature, not by the head wall temperature, due to the heat transfer through the piston ring and the liner wall. |
