Search Results

In order to simulate the valve behavior of an engine that uses a hydraulic lash adjuster (HLA), it is necessary to accurately reproduce the dynamic characteristics of the HLA in the model. Formerly, the model used values from drawings and values based on past experiences, and did not reflect actual driving conditions such as oil properties, leaked oil quantity, or oil aeration rate. We therefore developed a technique to reproduce HLA unit dynamic characteristics in a high-accuracy simulation. This representation was made possible using a unit excitation test to quantify the HLA unit dynamic characteristics in four categories: HLA stiffness, load response delay of the plunger, sinking displacement after relaxation, and lissajous curve of load vs. displacement. The effectiveness of this model calibration technique was confirmed through comparison of unit dynamic characteristics in a unit excitation test and a calibrated simulation.

Model-based Development (MBD) has been employed for engine development to reconcile the contradictory relationship between numerous functions and systems at a high level and in a short span of time. However, in actuality, as engines have become more advanced, it has become challenging to even satisfy the requirements of individual components. Moreover, reconciling multiple contradictory functions like engine power and strength and durability performance, as well as coordinating many related systems, requires an even higher level of skill. Such harmonization techniques require total optimization studies that cover a wide range of designs, and which requires several years of examination with current development processes. Multi-objective Design Exploration (MODE) methods [1] using parametric models [2] and surrogate models [3] are being used to shorten the development period and achieve more balanced designs.