EVALUATION OF TIMING CHAIN QUALITY AND ITS EFFECT ON TIMING SYSTEM OPERATION

Internal combustion engines are still the main source of propulsion for automotive vehicles. The timing system plays a very important role in the proper functioning of these engines. One of the widely used technical solutions to drive this system is the timing chain. However, in recent years, there has been a clear trend towards more frequent timing system failures. Many research works have focused on wear analysis or finite element method (FEM) modeling of chains. In contrast, it was decided to carry out a comparative study of the mechanical properties of new timing chains that are commercially available as spare parts for automotive workshops. The present study was carried out on timing system components of the popular Multijet 1.3 diesel engine used in Fiat, Opel, and Suzuki vehicles. Force-elongation curves were obtained for each of the tested chains, allowing their elongation under load to be estimated. In addition, breaking forces were measured, and breaking mechanisms were analyzed to compare the quality of the chains. Numerical parameters were proposed to estimate the quality of the tested chains. The chain tensioning forces resulting from the operation of the hydraulic tensioner were also estimated. The effect of the dynamic forces stretching the chain elastically on the timing accuracy during engine operation was also calculated.