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Technical Paper

Study of the Swelling in Lip Seal Application

2011-10-04
2011-36-0093
There are large numbers of variables that affect seal performance, for example, temperature, grease and dusty. This paper aims the study one of these variables, the swelling. Swelling is the absorption of the liquid by the rubber and this liquid absorption can deeply alter physical and chemical properties and hence change tensile strength, extensibility and hardness of the rubber. A review about seal and the characteristics of the seal performance will be made and also a study about what this phenomenon affects the seal performance. Thus the purpose of the present paper is to develop the conception of swelling by investigating the characteristics of swelling deformation.
Technical Paper

Investigations on Friction Losses within Front End Accessory Drives

2010-10-06
2010-36-0178
In order to increase the efficiency of internal combustion engines, Schaeffler Technologies recognized that it is necessary to identify the sources of energy losses, quantify such losses and to study ways to minimize them. Based on this premise, the Front End Accessory Drive parameters had to be investigated to locate where further potential enhancement is hidden. This paper aims to analyze and discuss about the main sources of energy losses occurring in FEAD and propose ways to optimize the system to the optimal range of efficiency and durability. Investigations showed that there are some loss points of the basic belt drive components which have good potential to be reducible, e.g., losses at bearings and belt.
Technical Paper

Transient Multi-Level Elastohydrodynamic Point Contact Algorithm Experimental Validation

2010-10-06
2010-36-0088
One of the great challenges of engineering teams nowadays is to overcome long and costly project experimentation phases. One effective way of decreasing such project demands is to come up with a firsthand prototype with high success probability. In order to do so, the project team should rely on robust numerical models, which can represent most of the real-life product behaviors, for instance system dynamics. For rolling element bearings, such dynamic models have to consider the dynamic interactions between its components, i.e., rolling elements and raceways. The only vibration transmitting points on rolling element bearings are the lubricated contacts. Therefore, in order to represent the full bearing dynamic behavior on a numerical model, an efficient transient contact model, which depicts the actual contact behavior, is fundamental.
Technical Paper

Contact Pressure Analysis of Rolling Bearing Raceways with Geometrical Singularities

2010-10-06
2010-36-0116
Sustainability is the focus of most engineering projects nowadays. The challenge of taking the efficiency to its maximum, in order to reduce the CO₂ emission, became so hard that even a minor innovation is a relevant step. Among the efficiency villains in automotive branch it is possible to quote the mechanical friction losses. One of the main factors concerning to these sort of losses is the contact pressure in rolling bearings. This pressure is highly influenced by singularities on raceways. Different geometry profiles can be a friction source, affecting the usage and leading to a wasteful exploitation. This paper aims to scrutinize the influence that different abnormalities on raceways has on the contact pressure of high speed and low load axial ball bearings. The study will be based on numerical simulations on a contact calculation software. The contact pressure will be evaluated around the edges of dented, bulged, grooved and ridged profiles.
Technical Paper

On the Influence of Housing Stiffness on Bearings Life for Manual Automotive Transmissions through Coupled Simulations

2011-10-04
2011-36-0151
One of the vital parts in the modern motor vehicle is the transmission. Any fault on the system can hazard the usage of the vehicle, especially if the fault occurs during the operation, in that case safety will be an issue. Thus, in order to improve reliability and durability of transmissions systems and its components, virtual simulations can help the designer to overcome faulty conditions during the design conception. However, many times the simulations do not relate to the real world application, due to simplification and assumptions that were formally known as appropriate. For that reason, during the process of designing a transmission bearing, it would be important to take into account the housing stiffness effects on the bearings. In this work, three different cases will be evaluated. In first case, bearings life will be simulated on an analytical software with a rigid housing.
Technical Paper

Basic dynamic load rating analysis of Clutch Release Bearings

2009-10-06
2009-36-0090
The design of Clutch Release Bearings (CRB) is usually based on angular contact ball bearings. This kind of bearings supports both axial and radial loads and the load limits depend directly on the contact angle. The CRB has its own particularity, since it is a radial angular contact ball bearing and its main load is on axial direction. Due to this special situation, this work is done to evaluate this CRB design according to the classical theory of bearing life calculation, developed by Lundberg and Palmgren (1947), which the standard ISO 281 is based on. The analysis is focused on the basic dynamic load rating of the bearing, which briefly means the expected load that the bearings support a life of 1 million cycles. This expectation follows a Weibull distribution with increasing failure ratio and a specific reliability.
Technical Paper

Methodology for Press Fit Validation

2012-10-02
2012-36-0452
Industrial applications frequently use interference between shafts and holes to fix parts together. The present work shows the methodology for validation of Finite Element calculus for press fitting a shaft in a dust shield hole. In the case of study the dust shield can be easily hit by shocks during transport and handling of the product. The shocks would change the position of the parts and consequently the new position could become a quality problem. The process of verification determines the factors which become the project more robust using the technical of Design of Experiment (DOE). The test and the computational simulation are shown as parallel way to determine the appropriate friction coefficient which could be used to predict the assembling and disassembling force for current project as well as the new design with similar features.
Technical Paper

Correlation between Simulations and Tests for Determining the Stress State on Raceways of Bearings Due to the Press Fitting and Loading at Test Rig

2012-10-02
2012-36-0453
Nowadays it is common for engineering applications the usage of software in parallel to test for a better understanding about some phenomena of study. The present paper intents to correlate different software and experimental practices to understand the stress state on the bearing raceway. The most important factor which determines the bearing life is the operational load. Others factors such as the stress state on the raceway due to press fit process can contribute to reduce the bearing life. A large number of factors have been studied to know the behavior of press fit. This paper, treats about the press fit and operational loading.
Technical Paper

Evaluation of the Method of Failure Analysis in Angular Contact Bearings through the Envelope Technique

2012-10-02
2012-36-0306
More efficient and more reliable methods to analyze the performance of the bearing test samples help to reduce validation time during development of rolling bearings. This paper presents a study of the impact on airborne noise and structural borne noise of especial prepared rolling bearings with angular contact submitted for durability tests. The study aims to link specific bearing failures to characteristics in airborne noise and structural borne noise using for instance the “envelope technique”. In the future these patterns will enable more effective online monitoring of failure evolution.
Technical Paper

Chamshaft Vibration Characteristic Assessment when Applying Needle Roller Bearings as Solution for Efficiency Increase

2012-11-25
2012-36-0628
One of the steps towards higher efficiency internal combustion engines (ICEs) is the application of new improved subsystems, with lower power consumption. One of such subsystems is the needle roller bearing valvetrain, where rolling bearings replace the common sliding bearings designs as camshaft supports, hence decreasing the frictional torque and increasing liquid power at the crankshaft. However, the first question to arise is the vibration characteristic of the system for the new design. In order to initiate the assessment of the vibration behavior of the camshaft, some fundamental investigations should be made, such as natural frequency identification. For that, one might benefit from virtually evaluate these characteristics via FEA / Rotordynamics algorithm, reducing the need for expensive experimental setups of the complete valvetrain. This work intends to assess the applicability of these both methods to the camshaft vibration problem.
Technical Paper

The Application of Camshaft Rolling Element Bearings as a Solution for CO2 Emission Reduction on Internal Combustion Engines

2012-10-02
2012-36-0254
As a common trend on the automotive development process, the increase in system efficiency became a major concern for design engineers nowadays. Several are the focuses at which such topic can be dealt with, including full systems upgrades, electrification and component level optimization. However, there are simpler ways to increase efficiency by only replacing construction concepts that have always been taken for granted. This is the case of replacing the sliding friction of the camshaft hydrodynamic bearings by rolling elements. The direct reduction of the power consumption, when applying rolling element bearings to the camshaft, is a straightforward method to increase the liquid torque available at the crankshaft, hence enabling downsizing. In this paper some design solutions and the structural integrity of the system will be assessed and, most of all, the reduction on the friction torque, hence the increase in system efficiency, which leads to CO₂ emission reductions.
Technical Paper

Influence of Operating Parameters in Grease Loss of Rolling Bearing

2012-10-02
2012-36-0252
The main purpose of the lubrication in the rolling bearing is to avoid and to reduce the metal to metal contact, thus it is possible to reduce the friction and to prevent the wear between the balls and the raceways. Consequently, the rolling bearing should work with grease or oil inside to guarantee an oil film between the balls and the raceways, thus this grease should stay inside the bearing. To avoid the grease loss the bearing normally may have a sealing but even so a little grease loss can occur. Hence the present investigation was initiated because of the need to understand a grease loss and the basic parameter that has influence on this. To help the elaboration of the experimental tests was used a DOE technique, thus it was possible to determinate simultaneously the individual and interactive effects of many factors that affect in the grease loss.
Technical Paper

Analysis of the Influence of Pre-Loading in the Rating Life Calculation of Tapered Roller Bearings Applied to Lightweight Front-Axle Differentials

2012-10-02
2012-36-0230
For intricate automotive systems that enclose several components, such as gearboxes, an important aspect of the design is defining the correct assembly parameters. A proper assembly can ensure optimized operating conditions and therefore the components can achieve a longer life. In the case of the support bearings applied to front-axle lightweight differentials, the assembly preload is a major aspect for an adequate performance of the system. During the design phase it is imperative to define reference values to this preload, so the application would endure its requirements. However, with the assistance of computer simulations, it is possible to determine an optimum condition of operation, i.e. optimum pre-load, which would increase the system reliability.
Technical Paper

Self-Heating Test to Evaluate Temperature Stabilization in the Rolling Bearing

2013-10-07
2013-36-0154
Heating generation in rolling bearings is a critical point for development and application, specially for heavy trucks. Several problems can occur in the rolling bearing and in the system when the temperature increases. For example, at high temperature levels the rubber sealing can change its proprieties and volume, creating a high interference at the contact with the rings. The grease can also be affected and modify its viscosity, generating a possible leakage, which is not allowed during life. This papers aims to study the heat generation and evaluate, experimentally, the temperature stabilization in clutch release bearings for heavy duty application. With this purpose, several tests were performed and the results were analyzed to find the main factors that can be influenced.
Technical Paper

Development of Clutch Release Bearings using Finite Elements Method.

2006-11-21
2006-01-2705
Clutch systems applications require that their components resist to high dynamics and static efforts that should be considered in the development process. These requirements are determined taking account the vehicle application, such as loadcases, materials, life time and environment conditions. In the case of CRB components generally the design is based on contact angular ball bearing. Normally static analysis are performed, computing stresses and displacements, however in this specification the results are checked using static and fatigue safety factors according to the strength assessment evaluation, Germany standard: FKM (Richtlinie - Rechnerischer Festigkeitsnachweis für Maschinenbauteile). Actually more powerful computers have reduced gradativally the cost for industries and with the constant improvements of FE programs, it is possible to simulate the complete assembly using contact interactions to get closer to the reality.
Technical Paper

Bearing Specification in Vehicle Gearbox using a Standard Simulation Methodology

2006-11-21
2006-01-2714
This paper presents a standardization model for the analysis of rolling bearings in transmission systems. A procedure was applied to assist gearbox prototype development. A solid methodology with robust software, based on international standards, allowed the development engineers to shorten simulation time. In this case, the calculations were performed taking into account system elasticity, which resulted in an exact calculation of the internal load distribution in the bearing, including contact pressure, tilted position and with rolling element profile, considering effects of lubrication conditions and contamination. The program also evaluates the resulting forces of gears, displacement, shaft deflection, contact pressure, stresses, torsion and inclination of the shafts. All the information processed aims at providing safe design, optimal solution and cost impact.
Technical Paper

Influence of Contamination between Clutch Release Bearing and Sliding Tube on the Clutch Pedal Hysteresis

2014-09-30
2014-36-0153
In recent years vehicle ergonomists have begun dedicating effort towards the study of human motion in the vehicle regarding moving comfort when using commands such as the steering wheel, gear shift and pedals. Correlation between subjective responses of human comfort and the maximum force achieved during the end-of-travel impact and the average slope of the force-displacement curve during the initial disengagement phase is difficult [1]. When end customers complain about clutch pedal actuation comfort, car salesmen and automakers change the entire clutch system, including pressure plate, clutch disc and clutch release bearing (CRB) to solve the problem and the suspicious root cause lies on the CRB. In most cases, previous analyses showed bearing still functional but strong contamination inside the bell housing, on the clutch and between the CRB with plastic housing and the sliding tube.
Technical Paper

Sensor of Position for Shifter Lever

2009-10-06
2009-36-0047
Nowadays, the development of new technologies in the automobilist industry has increasing the incorporation of electronics into mechanic systems, what reflects on safer and more reliable mechanisms. This study will present the development of a sensor detent pin for the switchgear unit, which combines an electronic sensor to a detent pin, reducing the number of mechanic components as consequence. Its main function are the comprehension of shifting and selection movement and gear positions (neutral and reverse), as well as send these informations by means of electric signals to a central computer.
Technical Paper

Performance Analysis of Gear Pair Design and Optimization by Genetic Algorithm

2015-09-22
2015-36-0431
Gear design techniques usually results on heavy drives that are contradictory to the tendency of mass reduction on the modern road vehicles applications. This paper proposes the utilization of a genetic algorithm to design and optimize geometric parameters of a transmission stage comprised of two steel gears. Although genetic algorithm is not an optimization technique on a straight sense, its use is increasing in several applications where the design space is multidimensional. In this study, the first fitness function proposed is a weighted average of critical performance factors on gears design such as total drive weight, tooth contact stress, bending stress and total space occupied by the assembly and the second fitness proposed considers the center distance influence and the tooth contact stress and bending stress. The weights of the average are modified in several simulations.
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