INVESTIGATING THE IMPACT OF CAM LOBE PHASING AND HYDRAULIC TENSIONER CHARACTERISTICS ON CHAIN DYNAMICS

The main objective of this study is to enhance the lifespan of a 2.2-litre automotive diesel engine that has faced challenges of extinction due to advancements in system technology, particularly the Fuel Injection Pump (FIP). Within this engine architecture, the FIP camshaft is linked with the FIP sprocket and driven by the crankshaft sprocket and chain system. The introduction of a new FIP, chosen based on drive ratios to meet fuel quantity requirements, presents a significant challenge in terms of increased chain load dynamics in the engine systems. To address this issue, two primary strategies are proposed: (i) reducing the FIP camshaft drive torque; and (ii) implementing adjustments to the hydraulic tensioner. Optimizing the FIP camshaft drive torque is an important factor for maintaining chain system performance and durability. Reductions in camshaft drive torque are achieved through strategic modifications to the cam lobe lift, phasing angle, and drive ratios. Simulation results from these assessments are compared with the base variant, providing valuable insights into the proposed optimization strategies. In addition to FIP camshaft torque optimization, another parameter to be investigated was the chain drive hydraulic tensioner characteristics. It was very evident. With the shift in dynamics of the drive torque system, it became necessary to reevaluate the characteristics of the tensioner. Various design parameters influencing chain tension from a hydraulic tensioner perspective are elaborated in the paper. Simulation results along with actual measurements are also discussed in detail. The drive torque optimization and tensioner system enhancement have helped in chain tension reduction within acceptable limits.