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Valve ticking noises within a cam actuated valve train can arise mysteriously. One valve train may produce valve ticking noises, while a second, geometrically similar valve train may perform more quietly. To better understand this phenomena, we examine in detail the prototypical motion of a valve driven by a rocker arm with cylindrical rocker pad. General features of a valve's motion through its guide, induced by a rocker arm with a cylindrical pad, are derived. From these general features of valve motion, guide contact points during lift events can be inferred, and as a result, detailed forces and moments acting on the valve may be derived. From this derivation of forces acting on the valve, a metric for assessing the propensity of a valve train to tick as a result of the valve stem impacting its guide is proposed. The proposed metric indicates how the likelihood of valve tick noise can be reduced through judicious choices for valve train geometries, clearances and surface finishes.

Modern engines are designed to operate at highly rated engine speed and load, which brings up challenges to the lubrication design of main and connecting rod bearings. Damages could occur on rod bearings due to high-speed relative sliding motion. Expensive cross drillings are often seen in today's engineering practice to ensure adequate lubrication in rod bearings. The objective of this study is to establish a methodology for predicting lubrication flows in rod bearings and use it to guide the engineering design. The high-speed nature of the crankshaft makes it difficult to acquire experimental data during its normal operation for better understanding the flow inside rod bearings and oil circuits. In the present study, the commercial CFD code, FLUENT, has been used to evaluate the flow characteristics within the rod bearings and oil passages connecting main bearing to rod bearing.

This paper presents a process for the selection of spring rate and pre-load for an adaptively controlled pivoting vane oil pump. The pivoting vane pump has two modes: high and low speed. A spring within the pump is installed to induce a torque that causes an adaptive displacement mechanism within the pump to move toward maximum oil chamber size. In low speed mode, two feedback regions are pressurized that produce torques that counter the spring generated torque. Together, both regions being pressurized by main oil gallery pressure tend to reduce pump displacement more at lower speeds than if only a single chamber is pressurized. At higher speeds, a solenoid switch turns off pressure to one of the feedback pressure chambers, thereby reducing feedback torque that counters spring torque. This enables higher pressure calibrations in this speed mode. In this paper, we identify a process for choosing the spring rate and pre-load that calibrates the adaptive displacement mechanism.