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Technical Paper

Transitioning from IC Engine to Electric Vehicle: An Optimized Wheel End Solution

2020-10-05
2020-01-1632
This paper discusses the change in vehicle parameters when moving from a conventional internal combustion engine to electric motor. It discusses the impact on the wheel end bearings. Typically these include higher GAWRs (Gross Axle Weight Rating) at lower center of gravity heights. These changes require bearings to handle higher loads. Typically, larger loads will increase the bearing size and with it the mounting interface dimensions to auxiliary components. Timken demonstrates an alternative bearing design that can handle higher vehicle GAWRs but would allow for continuity in the surrounding brake corner components – saving OEMs significant design costs and delays.
Technical Paper

Determination of Diffusion Capability of Oxygen Through Brake Pads From the Surface Towards the Interior

2020-10-05
2020-01-1616
The oxidation of raw materials, such as phenolic resin, in the pad during the braking depends on the temperature but also on the oxygen diffusion capability through the brake pad. Determination of oxygen diffusion is a key point in knowing how deep from the surface tribochemistry can take place. In previous work from RIMSA, it was observed that iron sulphide had been reacted below the surface of the brake pad, suggesting that tribochemistry does not only take place on the surface. The diffusion of oxygen through the pad is a drawback because it induces the matrix decomposition that contributes to intra-stop CoF instability and consequently worsens NVH. This study is focused on determining the oxygen diffusion through brake pads using oxidized iron sulphide particles as indicator parameter. Iron sulphide has a peculiar microstructure (rough microstructure) when it becomes oxide that can be recognized easily, making it a good marker.
Technical Paper

A Full-System Approach to Maximise Energy Efficiency of a Wheel Bearing

2020-10-05
2020-01-1631
Environmental sustainability is morphing Automotive technical development strategies and driving the evolution of vehicles with a speed and a strength hardly foreseeable a decade ago. The entire vehicle architecture is impacted, and energy efficiency becomes one of the most important parameters to reach goals, which are now not only market demands, but also based on regulatory standards with penalty consequences. Therefore, rolling drag from all bearings in multiple rotating parts of the vehicle needs to be reduced; wheel bearings are among the biggest in size regardless of the powertrain architecture (ICE, Hybrid, BEV) and have a significant impact. The design of wheel bearings is a complex balance between features influencing durability, robustness, vehicle dynamics, and, of course, energy efficiency.
Technical Paper

Wear Performances of Gray Cast Iron Brake Rotor with Plasma Electrolytic Aluminating Coating against Different Pads

2020-10-05
2020-01-1623
Gray cast iron brake rotor experiences substantial wear during the braking and contributes largely to the wear debris emissions. Surface coating on the gray cast iron rotor represents a trending approach dealing with the problems. In this research, a new plasma electrolytic aluminating (PEA) process was used for preparing an alumina-based ceramic coating with metallurgical bonding to the gray cast iron. Three different types of brake pads (ceramic, semi-metallic and non asbestos organic (NAO)) were used for tribotests. Performances of PEA coatings vs. different brake pad materials were comparatively investigated with respect to their coefficients of friction (COFs) and wear. The PEA-coated brake rotor has a dimple-like surface which promotes the formation of a thin transferred film to protect the rotor from wear. The transferred film materials come from the wear debris of the pads. The secondary plateaus are regenerated on the brake pads through compacting wear debris of the pads.
Technical Paper

A Study of the Interactions Between Phenolic Resin and Metal Sulphides and their Contribution to PAD Performance and Wear

2020-10-05
2020-01-1600
In order to keep the coefficient of friction stable, some additives such as metal sulphides, are included in the brake pads formulation. Previous work from RIMSA has shown that oxidation temperature range of the metal sulphides can be one of the key properties to explain their contribution to the performance and wear of a PAD. This new work is a step forward in the interpretation of the mechanism of sulphides as chemically active additives in the brake pads. Phenolic resin is the matrix of the brake pads and starts to decompose around 300 ºC in presence of oxygen and temperature. In order to establish a connection on between sulphide oxidation and phenolic resin degradation, several studies based on heat treatment of blends of different metal sulphides (Iron sulphide, Tin sulphide and Composite sulphide) with phenolic resin have been done. Then the material evolution was studied with techniques such as TGA - DSC, XRD, IR and SEM - EDS.
Technical Paper

Evaluation of a Low-Metals, Non-Petrochemical Coke for Use in Automotive Friction Materials

2020-10-05
2020-01-1603
A study was performed to compare the performance of automotive friction elements, each manufactured with one of two different coke fillers. Coke #1 is a conventional calcined petroleum coke, and coke #2 a proprietary, calcined coke manufactured from a non-petrochemical feedstock. Subject coke materials were fully characterized, physically and chemically. Both coke materials are similar in their respective physical properties, including morphology, hardness, and crush strength. However, there is a significant difference in the trace metal content of the two materials, with coke #1 containing a higher content of sulfur, calcium, iron, nickel, and vanadium than coke #2. Nickel and vanadium are considered potential environmental hazards. Initial friction element evaluation was performed using the J661 Brake Lining Quality Test Procedure (Chase Test). Ultimately each coke material was formulated into two different automotive brake elements.
Technical Paper

Design and Simulation of Braking System for ATV

2020-10-05
2020-01-1611
Design and Simulation Analysis of Braking system for ATV is carried out with the assistance of Ansys and MATLAB. Heat generated increases the temperature of the disc brake at the rubbing surface resulting in thermal stresses in the components of the braking system. Static, Structural, Thermal, Dynamic, Computational Flow Dynamics, Vibrational & Fatigue Behaviour of Ventilated brake disc Rotor, Hub and Brake Caliper are analysed. Stainless Steel, SS-410 material configuration has been considered for disc brake rotor and results obtained are analysed in terms of performance, longevity and efficiency. Braking efficiency and stopping distance curve are analysed from their characteristics plot. Vibrational Behaviour, Static and Structural Behaviour, Thermal Behaviour, Performance Efficiency, Flow Behaviour of Ventilated Disc Brake Rotor can be easily depicted with respect to Bump and Droop during Acceleration, High Climb and manoeuvrability.
Technical Paper

Rust is not a Must. Improvement of Discs Corrosion Resistance by Tuning of Cast Iron Alloying Elements and Microstructure.

2020-10-05
2020-01-1624
In the last decade, the increasing electrification of road transports has stimulated the look for new braking systems with a high corrosion resistance. This resulted in a fervent research activity behind the development of disc brakes with a reduced corrodibility under demanding tribocorrosive environments. Despite of this, a significant reduction of the cast iron disc corrodibility can be achieved not only by developing variously coated rotors, but also by modulating the intrinsic corrodibility of iron. This can be done by and ad-hoc refining of the cast iron: a) alloying elements concentration; b) microstructure; and c) carbon content and morphology. At this regard, in this contribution, the corrosion properties of a representative ensemble of cast iron specimens are reviewed.
Technical Paper

Anodization: Recent Advancements on Corrosion Protection of Brake Calipers

2020-10-05
2020-01-1626
Brake calipers for high-end cars are typically realized using Aluminum alloys, with Silicon being the most common alloying element. Despite the excellent castability and machinability of AlSix alloys, anodization is often necessary in order to provide to AlSix components the required corrosion resistance or when the braking system has to withstand to severe chloride-rich environments [1]. Even if the anodization process is known for almost 100 years, a continuous research and process optimization can lead to the development of anodic layers with enhanced morphological and electrochemical properties, which enable a prolonged resistance of calipers under endurance corrosive tests (e.g. >1000hours Neutral Spray Tests).
Technical Paper

Role of Attapulgite on Altering the Performance Properties of Cu-Free Brake-Pads

2020-10-05
2020-01-1601
Abstract: Attapulgite, a unique clay mineral is a crystalloid hydrous magnesium-aluminium silicate, composed of silicon oxide, aluminium oxide, magnesium oxide, iron oxide etc. having formula Mg5Si8O20(HO)2(OH2)4•4H2O. Its structure is somewhat between laminated and chain structure having very high surface area and porosity. Its magnesium silicate structure resembles a brick wall with every second brick missing. This leaves elongated porous channels that are highly absorbent. Its fibers were proven to be excellent substitute for asbestos in brake-pads. Hardly anything in details is reported on its exact role in controlling tribo-properties of friction materials (FMs) especially Cu-free FMs. Hence, in this work a series of brake-pads with five types was formulated and developed with increasing amount of attapulgite (0, 5, 10 and 15 wt. %) by compensating with inert barite particles in Cu-free FMs.
Technical Paper

Wear Evaluation of Niobium-Added Cast Iron for Brake Disc and Drum Applications

2020-10-05
2020-01-1627
Grey cast iron alloys for brake drum and brake disc applications are being developed with niobium additions and a range of equivalent carbon for commercial, passenger vehicle, and performance applications. The benefit of niobium in cast iron is based on the contribution of strength by matrix refinement for a given carbon equivalence that may permit the direct improvement of wear improvement or allow for an increase in carbon equivalence for a given strength. Proper carbon equivalency and pearlite stabilization contribute to an improved pearlite structure with an optimized distribution of graphite. These structures, when refined with niobium, demonstrate increased service life and reduced wear relative to their niobium-free equivalents as measured by lab dynamometer testing and by on-vehicle testing in passenger bus fleets.
Technical Paper

Root Cause Analysis and Structural Optimization of E-Drive Transmission

2020-09-30
2020-01-1578
We face a growing demand for so-called eAxles (electric axle drive) in vehicle development. An eAxle is a compact electric drive solution for full electric vehicles (and P4 hybrids) with integrated electric machine and transmission. The transmission can be rather simple using fixed gear with cylindrical gear steps but increasing demands on power and speed range as well as efficiency increase its complexity with planetary stages or switchable gear steps. Such an electro-mechanic system has different behavior than the classical ICE-driven powertrains, for example regarding NVH, where high frequency and tonal noise from gear whining and electro-magnetic excitation is an important comfort issue that needs to be understood and controlled.
Technical Paper

Multi-Domain NVH Model for the Complete Electro-Mechanical Power Unit

2020-09-30
2020-01-1584
Multi-domain NVH Model for the Complete Electro-mechanical Power Unit Yashwant Kolluru, Rolando Doelling eBike Department Robert Bosch GmbH Kusterdingen, Germany yashwant.kolluru@de.bosch.com rolando.doelling@de.bosch.com Lars Hedrich Institute of Informatics Goethe University Frankfurt Frankfurt, Germany hedrich@em.informatik.uni-frankfurt.de Acoustics and vibrations are amongst the foremost indicators in perceiving the quality of power units. Analyzing these factors is vital to improve the performances of electro-mechanical systems. This paper deals with development of a generic simulation method enabling the multi-domain vibro-acoustic modelling for the drive trains. Excitation's for these systems majorly arise from the electric motor and mechanical gears. The paper initially depicts a flexible gear model for gear whining, which are generated for reasons like gear tooth bending.
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