Especially for turbocharged SI engines, systems that allow to adapt the geometrical compression ratio offer advantages in terms of part load efficiency and maximum power output. In this study a conrod based two-stage VCR system with an eccentric piston pin bearing is investigated in fired engine operation by means of a specially designed measurement technique. For this purpose different sensor technologies were equipped to a VCR conrod and the oil supply system of a prototype crankshaft. The data transmission was realized by an optimized mechanical linkage system and a digital rotation telemetry system. The high-performance measurement technique presented in this paper enables a detailed analysis of the influencing parameters resulting from the fired engine operation, such as dynamic pressure stimulation in the crankshaft oil supply or the acceleration of the internal oil columns. The presented crank angle based measurement results of the system are obtained through fired testbench investigations on a three-cylinder full engine in the entire engine map, focusing on the speed range up to $n=6500{\min }^{-1}$ and loads up to $\mathrm{bmep}=21\mathrm{bar}$. A detailed analysis of the conrod system behavior in high and low compression ratio is shown. A key finding is, that the so called “hydraulic pretension” of the support chamber is necessary to meet the requirements for a stiff force transmission in the low compression ratio stage. The in-depth investigation contributes to the build up of a comprehensive system understanding and represents a solid base to expand the development process of conrod based two-stage VCR systems.

特别是对于涡轮增压 SI 发动机，允许调整几何压缩比的系统在部分负载效率和最大功率输出方面具有优势。在这项研究中，通过专门设计的测量技术，在点火发动机运行中研究了基于连杆的带有偏心活塞销轴承的两级 VCR 系统。为此，VCR 连杆和原型曲轴的供油系统配备了不同的传感器技术。数据传输通过优化的机械联动系统和数字旋转遥测系统实现。本文提出的高性能测量技术可以详细分析由点火发动机运行产生的影响参数，例如曲轴供油中的动态压力刺激或内部油柱的加速。所提出的基于曲柄角的系统测量结果是通过对整个发动机图中的三缸全发动机进行点火测试台调查获得的，重点是速度范围高达$n=6500{\mathrm{分钟}}^{-1}$ 并加载到 $\mathrm{bmep}=21\mathrm{酒吧}$. 显示了在高压缩比和低压缩比下连杆系统行为的详细分析。一个关键发现是，支撑室的所谓“液压预紧力”对于满足低压缩比阶段的刚性传力要求是必要的。深入调查有助于建立全面的系统理解，并为扩展基于连杆的两级 VCR 系统的开发过程奠定了坚实的基础。