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Technical Paper

Evaluation of future trends in conceptual design of belt tensioners for hybrid applications

2018-09-03
2018-36-0300
Recently the automotive marked is showing a trend towards increased adoption of hybrid vehicles to reduce emissions and increase vehicle efficiency. Fleet average targets for CO2 are compelling car manufacturers to reach very challenging fuel economy targets. The development of mild-hybrid vehicles has gained traction in this scenario. Another key driver has been the rapid evolution of electrical systems in new vehicles, ranging from advanced safety systems, driver assistance, and infotainment. This greater demand on electrical load has also contributed to the adoption of mild hybrid powertrains that work alongside traditional combustion engines and existing 12-volt systems. Many leading OEMs and suppliers are developing 48-volt architecture on the basis that it can achieve large efficiency gains at lower costs in the medium term than full electrification.
Technical Paper

In-Vehicle Experimental Tests to Evaluate the Performance of Alternator Pulleys

2017-11-07
2017-36-0433
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.
Technical Paper

Finite Element Analysis of Spring One-Way Clutch and Torsional Vibration Dampening Systems with Experimental Correlation

2017-11-07
2017-36-0406
In current Internal Combustion Engines (ICE), efforts have been employed in reducing emissions and fuel consumption. One of the alternatives is the reduction of the idling speed of the engines. However, such strategy involves great challenges from the aspect of torsional vibrations in the Front-End Accessory Drive (FEAD) system. Because it is coupled to the largest inertia of the FEAD assembly, the alternator pulley should provide a good vibration attenuation capability. The objective of this work is to demonstrate the development of an automotive component that employs two distinct types of springs: a clutch spring and a torsion spring. These elements are required in alternator pulleys to reduce torsional vibration generated by the crankshaft fluctuation and to avoid damage or durability issue with other components of the FEAD system.
Technical Paper

Analytical Models for Spring One-Way Clutch and Torsional Vibration Dampening Systems with Experimental Correlation

2017-11-07
2017-36-0407
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.
Technical Paper

Evaluation of Reliability Growth Based on Test Bench Data

2014-09-30
2014-36-0279
Reliability growth method is as a supporting tool for the production readiness plan of a new product line, in order to have an estimated probability of field failures during normal production. This is accomplished in the case study presented herein using prototypes test bench data. Evaluation is carried to verify its adequacy to support new product launch. Additionally, continuous improvement and evaluation of design change impact on product performance is another potential application of the method. In the case study a reliability growth planning and assessment is conducted prior to a new alternator pulley product line launch to confirm initial durability targets of the product could be achieved during transition from R&D validated prototype to the mass production items of the new product line. It includes efforts from Product Engineering during development stages until Start Of Production (SOP).
Technical Paper

Functional Testing of Alternator Pulleys in Chassis Dynamometer

2013-10-07
2013-36-0124
Alternators usually have a solid pulley to connect it to the Front-End Accessory Drive (FEAD) system. Current stringent emissions regulations and fuel economy push for new alternatives to meet goals such as, for instance, reduced idle speed and engine downsizing. However, achieving these goals could ultimately generate NVH issues, such as belt slip chirp noise, or reduced accessory-drive support bearing life due to the high vibration levels in the FEAD. Furthermore, increased demand for on-board electric/electronics systems are requiring the use of larger alternators, with bigger inertia, becoming an additional source of vibration.
Technical Paper

1-D MODEL DEVELOPMENT TO STUDY THE DYNAMIC BEHAVIOR OF THE MECHANICAL DIODE CONFIGURATION APPLIED TO ONE-WAY CLUTCH (OWC)

2009-10-06
2009-36-0230
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.
Technical Paper

1-D Dynamic Modeling and Sensitivity Analysis in Product Design

2008-10-07
2008-36-0134
Sensitivity analysis is a usual method to evaluate how “sensitive” is a product performance to changes in its design variables. This type of analysis identifies the critical variables related to product performance and other aspects that may have less demanding manufacturing controls. This paper presents a case study in the automotive market, applying the 1-D dynamic modeling as an auxiliary tool to the sensitivity analysis. The objective of this procedure is to reduce physical prototypes tests. This evaluation, if taken during preliminary design of the system, could give competitive advantages, with a reduction in product development cycle time and cost.
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