摘要
The relationship between engine mechanics and thermo-dynamics has been investigated by means of numerical simulation.The inherent mismatching between the mechanical behaviors and the thermodynamic process in internal combustion engine is identified,which is believed to be one of the important limiting factors of energy efficiency for conventional engines available in the current market.An approach for engine efficiency improvement through optimal matching between mechanics and thermodynamics(OMBMT)is proposed.An ideal matching model is defined and the conflicts due to the constraints among the mapping strokes in a 4-stroke engine are analyzed.A novel mechanical model is built for approaching optimal matching among all 4 individual strokes in a 4-stroke spark-ignition engine,which is composed of non-circular gears(NCG)and integrated with conventional slider crank engine mechanism.By means of digital mechanical model and numerical simulation,the matching gains among all 4 strokes are defined and calculated for quantifying the NCG engine efficiency improvement by comparing with a baseline engine.The potentials with the OMBMT implemented and the enhancements made by NCG mechanism for engines in terms of overall engine efficiency are reported.Based on the results achieved,it is recommended that the feasibility studies and the experimental validations should be conducted to verify the engine matching concept and effectiveness of the NCG mechanism engine model proposed,and the engine performance and NCG design parameters should be further optimized.
本文深入研究了发动机力学与热力学之间的匹配关系。定义了发动机力学与热力学之间的理想匹配模型,分析了四冲程发动机中由映射冲程之间的制约关系所引起的冲突,并建立了一种新颖的机械模型,用于逼近四冲程发动机中所有四个冲程各自的最佳匹配。该发动机模型由非圆齿轮(NCG)组成,并与传统的曲轴发动机机构相集成。通过数字化机械模型和数值模拟,定义和计算了所有四个冲程之间的匹配增益,以便通过与基准发动机进行比较来量化非圆齿轮发动机效率的提升。研究结果表明,随着发动机力学与热力学匹配的实施和非圆齿轮机构的引入,发动机的整体效率得到了显著提高。根据本文的研究结果,有必要进行可行性研究和实验验证,以验证或证明所提出的发动机匹配概念的正确性和非圆齿轮发动机模型的有效性,并且进一步优化发动机性能和非圆齿轮设计参数。
