Search Results

Vehicle alternator pulleys with one-way-clutch and vibration attenuation mechanisms have recently been adopted in modern vehicles in order to reduce or mitigate undesirable side effects of torsional vibrations generated by Internal Combustion Engines (ICE) during its normal operation. It is noticeable how excessive vibration can be particularly detrimental to the components of the Front-End Accessory Drive (FEAD) system. Increase of inertia forces due to the use of larger alternators along with the increase in torsional vibration amplitudes of downsized engines added up with lower idling speeds to reduce emissions have set a challenge for proper FEAD functioning and validation. In order to validate potential design solutions, in-vehicle experimental tests are an important approach. How to define an adequate test plan, execute test cycles and post-process bulk experimental data to assure proper assessment of alternator pulley alternatives is a key factor of success.

Among the alternatives for solving NVH (Noise, Vibration and Harshness) problems in automobiles, the alternator pulley has become one of the most promising alternatives in the Frond-End Accessory Drive (FEAD) of modern engines. The rigid pulley has evolved from a simple device whose only function is torque transmission to a system with much more complex functions. At this higher level of complexity, many innovative designs have been created, such as pulleys with overrunning function and pulleys with both One-Way Clutch (OWC) and vibration dampening functions, which are devices that require a high level of study in order to guarantee an adequate design of the system for each new application. This paper presents the steps taken in dimensioning two distinct types of springs: a clutch spring and a torsion spring, to be applied in alternator pulleys with OWC and vibration dampening systems.

Two types of One-Way Clutch (OWC) are commonly used in automotive applications – the roller and the sprag types. Some manufacturers claim the advantages of a different type of OWC having a mechanical diode OWC. The aim of this research is to study the mechanical diode system in order to point out reasons that explain why this configuration is not a spread out system in automotive applications that require lockup functionality. To achieve this objective the research work focuses on the development of 1-D models to simulate system behavior and evaluate product performance against design variables. Improvements to the system are suggested based on the simulation results.