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Viewing 1 to 30 of 66
2016-10-17
Technical Paper
2016-01-2204
Takafumi Mori, Masanori Suemitsu, Nobuharu Umamori, Takehisa Sato, Satoshi Ogano, Kenji Ueno, Oji Kuno, Kotaro Hiraga, Kazuhiko Yuasa, Shinichiro Shibata, Shinichiro Ishikawa
One effective and easy way to improve fuel economy for automobiles is to decrease viscosity of lubricants, as it brings less churning loss. However, this option creates a higher potential for thinner oil film, which could damage the mechanical parts. This paper describes a new low-viscosity gear oil technology which was successfully developed to improve wear at tapered-roller bearings in differential gear units, whereas achieving higher fuel economy performance. As for tapered-roller bearings in differential gear units protected by gear oils, one major damage is supposed to cause wear at large end face of rollers and the counterpart, so-called bearing bottom wear. In order to understand the wear mechanism, wear at rolling contact surface of rollers and the counterparts, so-called bearing side wear was additionally observed to confirm the wear impact on tapered-roller bearing.
2016-04-05
Technical Paper
2016-01-1103
Andrei Keller, Sergei Viktorovich Alyukov
Abstract The main indicators for mobility of a multipurpose wheeled vehicle are the maximum and average technical velocity (it is defined as the distance traveled divided by the time elapsed), and they are mainly determined by power-to-weight ratio and the parameters of the suspension. As our analysis shows, with the increase of the power-to-weight ratio of the vehicle and its weight, the growth rate of the velocity is reduced, and after reaching a certain value, the velocity remains almost constant. This is due to the fact that for operating conditions of the multi-purpose wheeled vehicle, movement on roads with different degrees of uneven distribution of the rolling resistance and adhesion, in both transverse and longitudinal directions, is typical.
2016-04-05
Technical Paper
2016-01-1130
Mike Johns, Heinz Kamping, Kristian Krueger, James Mynderse, Chris Riedel
Abstract Tapered roller bearings used to support pinion and differential gears in automotive drive axles perform best with accurate assembled preload. One of the most common high volume production assembly methods relies on bearing friction to adjust preload; however torque is an indirect measure of load, can be influenced by the raceway condition, and is difficult to control. A new method to measure preload utilizes frequency response to estimate axial preload from system stiffness. The stiffness can be measured dynamically and an assembly method automated to set preload without the need for torque or dimensional measurements. By eliminating the need for a torque signal, the raceway conditions which contribute to setting torque do not contribute to the preload setting accuracy. This study demonstrates the effectiveness of using frequency response to measure stiffness and estimate preload.
2016-02-01
Technical Paper
2016-28-0214
Prasad M. Rao, Nikhil Datar, Shailesh S. Kulkarni
Abstract The paper talks about the migration phenomenon that is observed in gears. The phenomenon discussed here is that observed on hypoid gears which due to their high spiral angles cause the issue to be more sensitive, but the analogy to other gears is applicable. Mahindra manufactures hypoid gear sets for its axles in-house that go on a wide range of its products; with performance benefits also come the stringent quality requirements for hypoid gear sets. Migration is the phenomenon that causes the furling or unfurling of individual gear teeth with respect to each other. This in effect causes the circular tooth spacing between two teeth to become non-uniform. This has a direct effect on the performance of the mated gear set.
2016-02-01
Technical Paper
2016-28-0227
Om Parkash Bhardwaj, David Blanco, Ketan Krishnamurthy, Bastian Holderbaum
Abstract As emission regulations are becoming increasingly stringent worldwide, multiple exhaust aftertreatment devices are considered in order to minimize diesel engine tailpipe emissions. For the typical diesel applications in developing markets like India, the fuel consumption is a very decisive selling argument for customers. The total cost of ownership needs to be as low as possible. To meet these competing requirements, the aftertreatment and engines must be optimized at the same time as the performance of the one system affects the other. In state-of-the-art calibration processes, the aftertreatment systems are considered separately from the calibration of the thermodynamics. This conventional approach makes it more challenging to achieve a simultaneous optimization of the fuel consumption and tailpipe emissions under transient operating conditions.
2015-09-29
Journal Article
2015-01-2787
Vladimir V. Vantsevich, Dennis R. Murphy
Abstract This paper starts with an analysis of design configurations of the drivelines with different power-dividing units (PDUs) of main dump truck manufacturing companies. As it follows from the analysis, improvements of articulated truck energy efficiency and reduction of fuel consumption by optimizing the power distribution to the drive wheels are still open issues. The problem is that a variety of operating and terrain conditions of dump trucks requires different wheel power distributions that cannot be provided by one set of PDUs employed in a truck. The central PDU in the transfer case was identified as the most important PDU among the five PDUs, which plays a crucial role in the power distribution between the front axle and the rear tandem of a 6×6 articulated dump truck. The paper formulates a constraint optimization problem to minimize the tire slippage power losses by optimizing the power distribution between the drive wheels.
2015-09-29
Journal Article
2015-01-2783
S Renjith, Vinod Kumar Srinivasa, Biswadip Shome
Abstract In an automotive power train system, the differential gear system plays a vital role of enabling the vehicle to transfer the engine torque to the wheels. The differential system consists of complex system of gears which are meshed with each other. Effective lubrication of the differential system ensures that the metal to metal contact between the gears is avoided. In addition, the lubricants also acts as a thermal medium to effectively dissipate the heat produced due to frictional resistances. For dipped lubrication system, the use of lubrication oil leads to a loss of transmission power, and the loss increases with increasing rotational speeds. Prediction and an understanding of the transmission loss inside the differential system is important as it provides a means to increase the power transmission efficiency. In addition, it provides insights to optimize the lubrication methods, gear profile, and gear housings.
2015-09-22
Technical Paper
2015-36-0164
Alexandre Rodrigues Pinho, Cleber P. Franco
Abstract Basic driveline configurations offered in mid-size trucks have a standard “open” differential. Open differentials allow smooth cornering, as the outside tire must spin faster on corners as it travels a larger arc, when compared to the inner tire. This system has a main problem when traction is lost, due to slippery roads, different friction coefficients between pavements or even when the axle is submitted to a twist ditch. All of the power goes to the wheel with the least traction and the pickup is stuck. In order to improve traction on these situations, limited slip differentials were developed. A limited-slip differential will prevent excessive power from being allocated just to one wheel, and thereby keeping both wheels in powered rotation. There are several solutions offered in the market, each one presenting different torque transfer capabilities.
2015-04-14
Technical Paper
2015-01-0710
Daniel Frazier, Kelly Williams, Javed Mapkar
Abstract Global vehicle emissions reduction initiatives have warranted the development and usage of new materials and processes not traditionally used in the automotive industry besides exclusive applications. To support this mandate, vehicle lightweighting via metal replacement and design optimization has come into sharp focus as a doubly rewarding effect; namely, a lighter vehicle system not only requires less road load power for motivation, but also allows for smaller, usually more efficient powertrain options, which tend to be more efficient still. The automotive industry has begun to embrace adapting composite materials that have typically been available only to the upper end of the market and specialty racing applications. The specific component detailed in this paper highlights the challenges and rewards for metal replacement with an injection molded, fiber reinforced plastic for usage in mass produced drivetrain systems, namely the Electronic Limited Slip Differential (eLSD).
2014-04-28
Technical Paper
2014-28-0003
Yathish Rao
Abstract Crown wheel can experience severe impact load when there is sudden drop in clutch pedal during vehicle operation. The higher core hardness at the pitch circle diameter of the gear teeth could drastically reduce the impact energy absorption characteristic of the material resulting in very fine micro crack on the teeth surface. The optimum core hardness range is very much necessary in order to improve the material impact energy absorption characteristic and subsequent balance between the impact & fatigue strength of the gear. The Brugger sample method is used to select the best core hardness range that exhibits optimum impact energy. The Brugger specimens with various core hardness bands, starts from 30 HRC to 45HRC, are prepared and tested for impact energy absorption capacity. The raw material with appropriate jominy value is used to prepare the specimen. Based on the Brugger test result, the optimum core hardness band is selected.
2014-04-01
Technical Paper
2014-01-1765
Ali Kolivand
Abstract Spherical involute surface topography for straight bevel gears including surface coordinates and normals are calculated. The significance of calculation of normal to the surface is mainly because it is needed for ease-off construction, tooth contact analysis and CMM measurement. The calculated surface and normals are then used to establish ease-off topography and the so-called surface of roll angle. The resultant surface of roll angle is used to allocate potential contact lines and contact ratio. The developed approach is applied to an example automotive differential straight bevel gear to calculate tooth surface, ease-off topography and surface of roll angle.
2014-04-01
Technical Paper
2014-01-0384
Tae-Sang Park, Sungho Jin, Jeon IL Moon, Seung-Han Yang
Abstract As is well known, the brake systems of vehicles are used in order to decelerate or stop the vehicle while the driving. The operational principle of the brake is the conversion of kinetic energy into thermal energy. In this case, the thermal energy is released to the atmosphere. Recently, electromechanical brakes (EMB) were developed in order to replace hydraulic brake calipers. Such brake-by- wire systems are composed of an electronic pedal, electronic control unit (ECU), wire, and an electromechanical caliper. A typical electromechanical brake is similar to existing floating brakes. In other words, an inner pad pushes out one side of a disc driven by the energy of a motor; by means of a screw-thread gear. Then, the caliper slides in the opposite direction by reaction force and moves the outer pad toward the other side of the disc. Then pads clamp both sides of the rotating disc and stop the wheel.
2014-04-01
Technical Paper
2014-01-0756
Abhijit Londhe, Suhas Kangde, Sreenadh N
Abstract A differential casing is one of the important elements in the vehicle power train, whose objective is to house differential gears and take different loads coming from these gears. The function of a differential is to drive a pair of wheels while allowing them to rotate at different speeds. While taking a turn, the outer wheel needs to travel more compared to the inner wheel. This is possible due to the differential which rotates them at different speeds. This Paper highlights a simplified methodology to capture the differential casing failure and to resolve the same. The methodology adopted was then correlated with the test measurements to increase the confidence. During physical tests, strains are measured at different orientations of the differential casing and correlated with simulation results.
2014-04-01
Journal Article
2014-01-1774
Darrell Robinette
This investigation utilizes a DFSS analysis approach to determine automatic transmission gear content required to minimize fuel consumption for various powertrain - vehicle systems. L18 and L27 inner arrays with automatic transmission design and shift pattern constraint parameters were varied to determine their relative influence on fuel consumption. An outer noise array consisting of two vehicles with various engines, final drive ratios and legislated emissions test cycles was used to make a robust transmission selection based on minimizing fuel consumption. The full details of the DFSS analysis method and assumptions are presented along with a detailed examination of the results. With respect to transmission design parameters, parasitic spinloss and gear mesh efficiency were found to be most important followed by the number of gears. The DFSS analysis further revealed that unique transmission design formulations are potentially required for widely varying engines.
2013-10-07
Technical Paper
2013-36-0467
Giovanni Giordani, Celso Fratta
In the light commercial vehicles and other wheeled vehicles, an open differential is a device that allows each driven wheel to rotate in different speeds during a curve or in limited grip conditions. On the other hand, when one of the wheels loses the grip the differential will direct all the torque available to the wheel that is spinning making the vehicle get stuck. In certain applications, such as electrical power line maintenance in rural areas requires a larger capacity drive vehicles due to low friction terrain. To comply with this application requirement was developed the locking differential speed sensitive that pulls both wheels at the same time offering full locking axle and increasing the traction capacity of the vehicle. The system automatically unlocks the wheel with higher speed when the speed is different between them as happened in a curve.
2012-10-02
Technical Paper
2012-36-0284
Christoph Karl, Roman Haas
Prop shafts and differentials have been improved continuously. They are getting even more efficient and more lightweight. But the interface between these two parts looks still the same since more than 50 years what gives us a great chance for improvement. Rear or front axle differentials are currently fitted with a flange. This flange is necessary to connect the prop shaft frictionally with the differential during the final assembly. The substitution of universal joints by constant velocity joints gives the possibility of replacing a flange connection by a compact, lighter screwed connection. This paper will present a new single piece screwed solution which fits perfectly on the demands of modern all- / rear - wheel driven cars.
2012-10-02
Technical Paper
2012-36-0230
Gabriel Figlie Macedo, Fabio Nonato
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.
2012-06-13
Technical Paper
2012-01-1543
I. Karagiannis, Stephanos Theodossiades, H. Rahnejat
The dynamics of automotive differentials have been studied extensively to improve their efficiency and additionally, in recent years, generated noise and vibration. Various mathematical models have been proposed to describe the contact/impact of gear teeth pairs. However, the influence of vehicular cruising speed on the resisting torque has not been considered in sufficient detail. This can lead to unrealistic predictions with regards to loss of contact of teeth pair, a phenomenon which leads to NVH issues. The current work presents a torsional model of a hypoid gear pair. The resisting torque is a function of the traction force and aerodynamic drag, whilst the vehicle is cruising at nominally constant speed. The pinion input torque is derived through assumed instantaneous equilibrium conditions. In this approach, realistic excitation capturing the vehicle's driving conditions is imposed on the dynamics of the hypoid gear pair.
2012-04-16
Technical Paper
2012-01-0164
Michael Frechette, Gary Sroka, Matthew Bell
The benefits gained by superfinishing rear-axle hypoid gearsets are now well documented. Friction, wear and operating temperature are significantly reduced. The main impediment to commercially implementing this process, however, is that it increases manufacturing cost in terms of process speed, work in process and labor. The cost of superfinishing can be significantly reduced by employing a newly developed and fully automatable drag finishing process. The most primitive form of drag finishing occurred when Roman soldiers dragged their armor through sandy fields for obtaining a mirror-like appearance. Today's drag finisher, of course, is much more sophisticated. A circular turret is located above a circular bowl containing loose, ceramic media. Parts are attached to multiple rotating spindles on the turret, which in turn are immersed in the media in the bowl below, and are dragged through the media. This generates a high flow of media over the gearsets.
2012-04-16
Technical Paper
2012-01-0813
Suresh Naidu Reddy, Vivek H Yadav
In the current scenario of growing demand for lightweight designs for improving fuel economy and reduced cost, the focus is on optimum design solutions. This calls for improved and accurate prediction capabilities in terms of life or cycles the design can sustain in real world usage profile. Conventionally, the differential casings are simulated and designed for worst loads experienced and the approach used is infinite life design for these loads. But, this would lead to overdesign and increase weight. To counter this problem the methodology for fatigue analysis for the derived duty cycle of differential casing is developed. The critical regions can be identified based on life and the solutions can be worked out without major design changes. This paper briefs the nonlinear static load cases required for deriving the block cycle loading and incorporating these as a duty cycle in fatigue solver.
2012-04-16
Technical Paper
2012-01-0305
Matthew Fox, John Grogg
The open (standard) differential provides an important function in vehicle dynamics and handling by splitting the applied driveline torque and allowing each wheel or axle to spin at different speeds. This function is necessary to eliminate axle bind-up while negotiating turns. However, it inherently impedes optimal traction and mobility performance by allowing the available torque to be limited by the wheel or axle having the least amount of traction. Loss of traction could result in loss of driveline torque control and a resulting loss of vehicle control. This loss of control could be catastrophic in the case of higher speed maneuvers. The proposed electronically controlled hydraulic limited slip differential solution corrects this problem, seamless to the driver, while maintaining the fundamental open differential function. Furthermore, this system maintains efficient forward motion compared to other solutions that slow the vehicle down while expending valuable energy.
2011-10-04
Technical Paper
2011-36-0078
Matthias J. Derse, Mauro Moraes de Souza
In light of the global trend to reduce CO₂ emissions, the pressure on the automotive industry to further reduce vehicle weights is increasing. Moreover, there is also a need to make more efficient use of the space available, in order to take account of new requirements relating to crash safety and increasing function integration (including dual-clutch transmissions and hybrid applications). When it comes to gears, the differential still offers great potential as regards the reduction of weight and size. This paper will present a new, housing- or cage-less differential that achieves the above-mentioned development goals while keeping to the familiar and tested design principle of the bevel gear set. Simultaneous product and process development and the use of high-precision forging technologies facilitate cost-effective production of this new differential.
2011-10-04
Technical Paper
2011-36-0105
Ricardo Shindi Hosokawa, Roberto Stevaux, Alessandro Martins
For environmental issues, the Automotive Industry is always looking for opportunities in terms of weight and size reduction. This consequently results in fuel consumption reduction. This new concept is more compact, lighter, quieter, more efficient and with higher performance. These attributes are possible by a completely new differential design. The architecture of this space-saving component is completely different from traditional differential designs. Instead of using conventional differential pinions, the Lightweight Differential has spur gears arranged as a planetary gear set in one plane, as used in automatic transmissions. This means that the required space and weight are significantly reduced and the potential torque capacity is noticeably increased. The lightweight or spur gear differential has enormous advantages.
2011-05-17
Technical Paper
2011-01-1557
Ioannis Nerantzis, Emmanouil Athanasopoulos, Athanassios Mihailidis, Stephanos Theodossiades
Vehicle handling is heavily influenced by the torque distribution to the driving wheels. This work presents a newly developed differential, designed to actively control the driving torque distribution to the wheels. The new device incorporates an electric machine, which can operate either as a motor or generator. A control unit monitors signals from various sources in the vehicle, such as steering angle, yaw acceleration and wheel rotational speed. Then, a control algorithm takes into account the steering angle rate and the vehicle speed in order to determine the suitable difference between output torque values. The handling improvement capabilities are evaluated by simulating in ADAMS/Car the driving behavior of a vehicle equipped with the new differential. The model that has been used to simulate vehicle handling is that of a Formula SAE type racing car.
2011-05-17
Technical Paper
2011-01-1551
Xia Hua, Teik Lim, Tao Peng
Spiral bevel gear dynamics are significantly affected by the flexibilities of shafts and bearings. In this study, a new shaft-bearing model has been proposed for computing the effective support stiffness. The results are applied to the lumped parameter dynamic model of spiral bevel geared rotor system with 3-bearing straddle-mounted pinion configuration. Also, using the multi-degree of freedom lumped parameter dynamic model and quasi-static three-dimensional finite element tooth contact analysis program, the responses of two typical shaft-bearing configurations used in automotive applications, that are the 3-bearing straddle mounted pinion configuration and the 2-bearing overhung mounted pinion configuration, are compared. The comparative analysis along with a set of parametric studies highlights their different contributions to the spiral bevel gear mesh characteristics and dynamic response.
2011-04-12
Technical Paper
2011-01-0717
Venkata Ramana Raju Penumatsa, Bhaskara Kishore Chirravuri
Bevel planetary in the differential helps the vehicle in negotiating a turn and splitting the torque between the axles. The bevel gear differential assembly consists of two bevel pinions, two side gears, differential shaft and washers, enclosed in differential housing. Bevel pinions mounted on the differential shaft act as idlers for power transfer from carrier to side gears which are splined to axles. This paper is aimed at evaluation of stress cycles in fillets of bevel pinion in a differential. Generally analysis of bevel pinion is carried out using specialized codes. These codes ignore the stiffness of differential housing and differential shaft and effect of surface hardness on the gear tooth. Hence, in this work, a method has been proposed to simulate the complex mechanism of differential assembly with simple static analysis using commercial Finite Element Analysis Software ABAQUS/STANDARD.
2011-04-12
Technical Paper
2011-01-0775
Pulakesh Chakraborty, Suhas Dodamani, Rajnish Singh
As the automobile industry in India is growing fast and competitive, there is a need to design the vehicle and its parts at most cost effective. This paper gives the details of design optimization and cost effective methodology followed to develop a Single Stalk Combination Switch, without degrading the end user delight. This paper describes various design criteria affecting the combination switch design.
2008-04-14
Technical Paper
2008-01-0302
Vladimir Ivanović, Zvonko Herold, Joško Deur, Matthew Hancock, Francis Assadian
In order to support active limited slip differential (ALSD) modeling work, a test rig of a DC motor-actuated ALSD has been developed. The test rig is equipped with a torque servomotor that provides a precise closed-loop control of the clutch slip speed, as well as with sensors of clutch torque, and DC motor position and current. In addition to the test rig, a precise wet clutch experimental setup has been developed by using the differential hardware. The setup provides direct measurements of the clutch pack axial force, the separator plate temperature, and the press plate axial position. The paper describes the ALSD test rig and the wet clutch experimental setup, presents and analyzes characteristic experimental results, and outlines the main ALSD modeling results.
2008-04-14
Technical Paper
2008-01-0500
Kosuke Yamanaka, Shirou Nakano
We have developed a new active-front-steering system which contributes to the vehicle safety improvement. This system includes two motors and differential gear unit in one body. It makes possible to compensate steer angle and control reactive torque simultaneously. This means driver assistance control without interference on driver. This concept has a potential to omit tuning process on each vehicle, and reduce weight and cost. We have proved the effect of driver assistance control by this system.
2007-05-15
Technical Paper
2007-01-2295
T. M. Cameron, C. Hewette, T. McCombs, D. DeGonia, T. C. Jao
The torsional natural frequencies of axles equipped with limited slip differential clutches depend on whether or not the tires and clutches are slipping since the effective inertia at each end of the axle is different for slipping and non-slipping conditions. Limited slip axle vibrations are typically analyzed for one tire slipping and the other not since that is the case for which the limited slip clutches are used. Vibrations often arise, however, during normal turning when both drive tires have good traction.
Viewing 1 to 30 of 66