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SAE International Journal of Passenger Cars Mechanical Systems
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Development of Axial Force Testing System for Wheel Bearing

SAE International Journal of Passenger Cars - Mechanical Systems

Pan Asia Technical Automotive Center Co.-Lu Zhang
Zhejiang Wanxiang Precision Industry Co.-Chao Wen, Tong Luo, Dejie Huang, Yu Liu
  • Journal Article
  • 2017-01-2522
Published 2017-09-17 by SAE International in United States
The actual installed conditions of 1st, 2nd and 3rd generation of wheel bearing were introduced. The theoretical factors of the axial fastening force for the axle (or CVJ bolts) and nuts were analyzed and the requirements for building up a precise axial force test system were given out. Four testing plans were discussed for the requirements. Based on the cases, the axial force test system was built up, and the axial force test was successfully carried out for the front wheel bearing of a car.
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Wheel Bearing Brinelling and a Vehicle Curb Impact DOE to Understand Factors Affecting Bearing Loads

SAE International Journal of Passenger Cars - Mechanical Systems

General Motors LLC-Robert G. Sutherlin
  • Journal Article
  • 2017-01-2526
Published 2017-09-17 by SAE International in United States
As material cleanliness and bearing lubrication have improved, wheel bearings are experiencing less raceway spalling failures from rotating fatigue. Warranty part reviews have shown that two of the larger failure modes for wheel bearings are contaminant ingress and Brinell damage from curb and pothole impacts. Warranty has also shown that larger wheels have higher rates of Brinell warranty. This paper discusses the Brinell failure mode for bearings. It reviews a vehicle test used to evaluate Brinell performance for wheel bearings. The paper also discusses a design of experiments to study the effects of factors such as wheel size, vehicle loading and vehicle position versus the bearing load from a vehicle side impact to the wheel. As the trend in vehicle styling is moving to larger wheels and low profile tires, understanding the impact load can help properly size wheel bearings.
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Fatigue Performance Improvements of Wheel Bearing Rolling Elements

SAE International Journal of Passenger Cars - Mechanical Systems

NN, Inc - Precision Bearing Components-Sebastiano Rizzo, Stefano Pagliassotto
  • Journal Article
  • 2017-01-2524
Published 2017-09-17 by SAE International in United States
Wheel bearings are safety-critical automotive components. For this application, the steel rolling elements are subjected to fatigue failure and therefore play a key role in overall bearing fatigue life performance. This performance is influenced by metallurgical, mechanical, and physical properties obtained by precise manufacturing process parameters. These properties are continuously analyzed and are evolving at all bearing manufacturing companies. Last year, the Precision Bearing Components (PBC) Group of NN Inc., a global supplier of steel rolling elements for wheel bearings, developed a non-conventional heat treatment process for 100Cr6 (SAE 52100) rolling element steel for improved fatigue performance.The results of wheel bearing rolling contact fatigue (RCF) tests showed the importance of rolling element dimensional stability. As retained austenite transformed to the martensite phase, rolling element volume increase occurred, leading to fatigue failure. The fatigue life of rolling elements is directly proportional to their dimensional stability.As a result of the experimental tests, a project was initiated with the goal of increasing the dimensional stability of rolling elements, thereby enhancing RCF performance. The use of another conventional steel…
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Sizing Next Generation High Performance Brake Systems with Copper Free Linings

SAE International Journal of Passenger Cars - Mechanical Systems

Adam Opel AG-Max Votteler
General Motors LLC-David B. Antanaitis, Michael Shenberger
  • Journal Article
  • 2017-01-2532
Published 2017-09-17 by SAE International in United States
The high performance brake systems of today are usually in a delicate balance - walking the fine line between being overpowered by some of the most potent powertrains, some of the grippiest tires, and some of the most demanding race tracks that the automotive world has ever seen - and saddling the vehicle with excess kilograms of unsprung mass with oversized brakes, forcing significant compromises in drivability with oversized tires and wheels. Brake system design for high performance vehicles has often relied on a very deep understanding of friction material performance (friction, wear, and compressibility) in race track conditions, with sufficient knowledge to enable this razor’s edge design. With significant restrictions in copper content of automotive brake linings becoming reality in California and Washington State in 2021, and a more or less complete phase-out of copper in linings occurring in 2024, one of the key ingredients of high performance linings - critical for heat transfer, high temperature tribofilms, and medium to high temperature friction - can no longer be used.This paper looks at dynamometer-based performance…
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A Study of the Disc Scoring Generation Principle and Reduction

SAE International Journal of Passenger Cars - Mechanical Systems

Hyundai Motor Co.-ByeongUk Jeong, Hyong Tae Ryu
Myunghwa Ind Co.-Chang Jin Kim
  • Journal Article
  • 2017-01-2501
Published 2017-09-17 by SAE International in United States
Owing to the enhanced performance of engines these days, more heat should be dissipated in the braking system. Success of doing this properly causes more heat to the disc in the brake system which results in the deformation or scratches on the surface of it and a reduction in the appearance of the product. A study for detailed factors to aggravate this was done as a solution to prevent these from happening. In this paper, we present our work based on experiments to study MPU (Metal Pick Up) of the pad and the scoring(scratching) of the disc. MPU of which the main component is “Fe”, is formed through the process of fusing the separated materials from the disc by friction with the pad, and by local heat generation to the pad. [1,2,3,4,5] The occurrence of MPU and the possibility of the disc scoring resulting from this were studied by noting “Fe” which was transferred to the surface of the pad to different extent and degree of segregation according to the roughness of the disc. For…
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Study of Difference in Friction Behavior of Brake Disc Rotor with Various Surface Textures during Running-In by Using Simple Model

SAE International Journal of Passenger Cars - Mechanical Systems

KIRIU Corp.-Toshikazu Okamura
  • Journal Article
  • 2017-01-2511
Published 2017-09-17 by SAE International in United States
The most fundamental function of an automobile brake system is assuring stable braking effectiveness under various conditions. In a previous paper (2004-01-2765), the author et al. confirmed that the friction behavior of disc brakes during running-in depends on both the friction materials and discs’ friction-surface textures. Various friction pairs were tested by combining discs finished with roller-burnishing and grinding and five friction materials including NAO and low-steel. Some NAO material exhibited large effects on the difference in friction behaviors between the discs’ surface textures. A disc finished with roller-burnishing needed a longer running-in period than that with grinding. In another paper (2011-01-2382), a further experiment was conducted by combining eight surface textures (finished under four turning conditions with and without additional roller-burnishing), two NAO materials, and two rotational directions. Notable phenomena were observed, e.g., the coefficients of friction had a peak at the early stage of testing and there was a difference in those at the final stage between surface textures. These behaviors were determined to be due to the contribution of aggressiveness and adhesiveness…
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The Effect of Outer Ring Distortion on Wheel Bearing Friction Torque

SAE International Journal of Passenger Cars - Mechanical Systems

General Motors LLC-Stacey Scherer
  • Journal Article
  • 2017-01-2521
Published 2017-09-17 by SAE International in United States
Wheel bearing friction torque (“drag”) directly contributes to vehicle fuel economy and CO2 emissions. At the same time, one of the most important factors for long-term durability of wheel bearings is effective seal performance. Since these two factors are often in conflict, it is important to balance the desire for low friction with the need for optimal sealing. One factor that affects wheel bearing sealing performance is the distortion of the outer ring that occurs when the bearing is mounted to the steering knuckle with fasteners. Minimizing this distortion is not just important for sealing, however. This paper explores the relationship between the outer ring distortion and the resulting friction torque. A design of experiments (DOE) approach was used in order to study the effects of the fastening bolt torque, constant velocity joint (CVJ) fastening torque, and outer ring distortion on component-level drag. The correlation shows the importance of maintaining raceway roundness in order to both improve sealing effectiveness and reduce friction within the wheel bearing.
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Seal Failure Analysis Method of Wheel Bearing

SAE International Journal of Passenger Cars - Mechanical Systems

Shanghai Volkswagen Automotive Co., Ltd-Peiqing Qian
Zhejiang Wanxiang Precision Industry Co.-Dejie Huang, Xu Zhou, Chao Wen, Yu Liu
  • Journal Article
  • 2017-01-2527
Published 2017-09-17 by SAE International in United States
The seal structure and key parameters of wheel bearing were introduced. Research on sealing failure diagnosis, abrasive scratch analysis, residual interference, and abrasion reconstruction was carried out for a typical seal structure. Based on these methods of scientific failure analysis, eight causes of seal failure were summarized systematically, which were important for the guidance of seal design and failure analysis of wheel bearings.
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Performance Prediction of Automotive Wheel Bearing Seals

SAE International Journal of Passenger Cars - Mechanical Systems

Iljin Global-Seungpyo Lee, Mincheol Park
  • Journal Article
  • 2017-01-2525
Published 2017-09-17 by SAE International in United States
The primary functions of bearing seals are to prevent lubrication from escaping and foreign material from entering, the effectiveness of which is determined by the design of the seal lips. Bearings with low friction rotation are in great demand in the automotive market as a direct result of enforced vehicle fuel economy and reduced CO2 emissions regulations. Therefore, bearings with good sealing function and low friction rotation are required. This makes designing a seal challenging as the ideologies of high seal-ability and low friction rotation tend to be contradictory. Current estimations of bearing seal friction or rotational torque require significant time and cost through empirical methods of trial and error. Research into the estimation of bearing rotational torque through numerical analysis, based on finite element methods, is the focal point of this paper. This development includes the calculation of bearing rotational torque using an axisymmetric model from the commercial software, ABAQUS. The seal rubber material properties were analyzed using hyperelastic methods for increased accuracy followed by seal rotational torque being calculated using the analysis results…
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Pressure Following Strategy for Conventional Braking Control Applied to a HIL Test Bench

SAE International Journal of Passenger Cars - Mechanical Systems

Politecnico di Torino-Enrico Galvagno, Antonio Tota, Alessandro Vigliani, Mauro Velardocchia
  • Journal Article
  • 2017-01-2496
Published 2017-09-17 by SAE International in United States
Brake systems represent important components for passenger cars since they are strictly related to vehicle safety: Anti-lock Braking Systems (ABS) and Electronic Stability Control (ESC) are the most well-known examples. The paper is focused on the characterization of the braking hydraulic plant and on the design of a pressure following control strategy. This strategy is aimed at pursuing performances and/or comfort objectives beyond the typical safety task. The low-level logic (focus of the paper) consists of a Feedforward and Proportional Integral controller. A Hardware In the Loop (HIL) braking test bench is adopted for pressure controller validation by providing some realistic reference pressure histories evaluated by a high-level controller. Results prove that innovative control strategies can be applied to conventional braking systems for achieving targets not limited to braking issues, i.e., comfort or NVH tasks.
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