Criteria

Text:
Content:
Display:

Results

Viewing 1 to 30 of 57
Technical Paper
2014-04-28
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. The current gear-set with optimized core hardness are tested for gear set fatigue & impact shock load.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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. While effective, this design has the problem that there is a difference in the wear of the inner and outer pads.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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. The shift pattern constraint of minimum operating speed in gear that establishes the downshift line was found to be most significant while all other shift parameters proved to be negligible.
Technical Paper
2013-10-07
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. For this project the locking system was applied to a light truck, which is an innovation in the light commercial vehicles Brazilian market.
Technical Paper
2012-10-02
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. This paper presents a study on the influence of preload on the rating life of tapered roller bearings applied to light-weight front axle differentials, evaluating how preload affects several key parameters such as rating life and displacement of components, taking into account the flexibility of the surrounding differential housing.
Technical Paper
2012-10-02
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.
Technical Paper
2012-06-13
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. The dependence of the gear pair meshing stiffness on the torque amplitude is also considered using Tooth Contact Analysis (TCA).
Technical Paper
2012-04-16
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. A number of other systems available today govern and deprive the driver of the sense of confident unimpeded control while the proposed system maintains it.
Technical Paper
2012-04-16
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. This results in identifying critical regions based on fatigue life using quasi static fatigue approach.
Technical Paper
2012-04-16
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. By a judicious choice of media and a chemical accelerator, the hypoid gearsets can be superfinished in less than five minutes to an Ra of less than 0.15µm, while maintaining gear geometry.
Technical Paper
2011-10-04
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.
Technical Paper
2011-10-04
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. It's possible to save up to 30 percent weight compared with a classic bevel gear differential while creating up to 70 percent more axial space due to the streamlined design.
Technical Paper
2011-05-17
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. Results are obtained using the following three types of differentials: an open differential, a limited slip differential and the new actively controlled device.
Technical Paper
2011-05-17
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. Though spiral bevel gear is used in this study, the methods and conclusions could be reasonably applied to other types of gear applications especially non-parallel types.
Technical Paper
2011-04-12
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. This analysis is carried out at nine equal time steps for a given base pitch rotation of bevel pinion.
Technical Paper
2011-04-12
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.
Technical Paper
2008-04-14
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.
Technical Paper
2008-04-14
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.
Technical Paper
2007-05-15
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. Models for estimating the torsional natural frequencies of limited slip axles are presented for the cases of: Non-slipping clutches, neither tire slipping Non-slipping clutches, both tires slipping Non-slipping clutches, one tire slipping, one tire not slipping Slipping clutches, neither tire slipping Slipping clutches, both tires slipping Slipping clutches, one tire slipping, one tire not slipping Vibration frequencies varying from below 1 Hz to about 500 Hz are shown to arise due to differing conditions, and experimental data are presented that support the theoretical conclusions.
Technical Paper
2007-04-16
Nonnwats Anantapal
There are many types of joint that are popularly used nowadays; and the Universal joint is one of the types. However, the application of the Universal joint limits the angle of the driving axle and the driven axle not less than 160 degrees. The lower degree of this angle will require unnecessary higher input torque because the input load increases. Therefore, in this article presents the application concept of Universal joint at the angle lower than 160 degrees, such as: Limited Slip Differential, Center Differential, Viscous Coupling and Clutch.
Technical Paper
2006-04-03
Jae Lew, Damrongrit Piyabongkarn, John Grogg
Vehicle rollover has the highest fatality rate among non-collision vehicle crashes. This paper introduces a control scheme with electronically controlled limited slip differential (ELSD) to prevent vehicle rollover. Although the analysis focuses on only an un-tripped and on-road scenario which is a small portion of vehicle rollover accidents, it intends to minimize the dynamic rollover propensity by meeting the National Highway Traffic Safety Administration's (NHTSA) fishhook test. A nonlinear model of planar vehicle dynamics with roll motion is analyzed, and the general characteristics of ELSD are presented. Based on that, a rollover mitigation algorithm is proposed. Finally, a computer simulation demonstrates the effectiveness of the rollover mitigation algorithm.
Technical Paper
2006-04-03
Damrongrit Piyabongkarn, Jae Lew, John Grogg, Robert Kyle
Typical traction control systems based on brake intervention have the disadvantage of dissipating an amount of energy roughly equal to that spent in biasing the high-friction wheel. Fully locked differentials achieve the best possible longitudinal traction but, in situations such as slippery or split-friction (split-μ) surfaces, the lateral dynamics of the vehicle can be degraded and deviate from the driver's intended direction. This paper presents an active stability control strategy using electronic limited slip differentials to enhance the vehicle lateral dynamics while preserving longitudinal motion. The proposed control system includes stability enhancement of the traction control and yaw stability control. The stability-enhanced traction control is evaluated under the condition of straight-line full-throttle launching on a split-μ ice/snow surface. The experimental data show a significant stability improvement in a traction mode. The test maneuvers for high-speed yaw stability control include a slalom maneuver and an open-loop sine-steer maneuver on a low-friction (packed-snow) surface.
Technical Paper
2004-03-08
Jerry Kinsey
Limited slip differentials offer significant performance benefits over standard differentials. Depending on the style and design, mobility and/or handling can be improved. Oftentimes, one must be improved at the expense of the other. For a speed sensitive limited slip differential, mobility can be improved by aggressive tuning. This would normally give adverse handling effects, due to the aggressiveness. If the differential is tuned for handling characteristics, mobility will be compromised, due to the moderate tuning. To optimize the performance, tuning must be adjustable according to the vehicle's input parameters. This paper will show the benefits of adjustable tuning in handling, mobility, and compatibility with other vehicle systems, such as ABS, Traction Control, and Stability Control.
Technical Paper
2003-11-18
Dirk Spindler, Georg von Petery
In passenger car axle differentials, axially preloaded tapered roller bearings have been used exclusively since their rigidity and life are sufficient for this application. In real life applications, the bearing preload during transmission life is reduced due to wear in the contact between the roller and the rib, and preload can even be lost completely. This preload loss in the bearing supports has an immediate effect on the tooth contact between the pinion and the ring and it causes noise during operation and reduced gear teeth life. INA has now developed a new bearing design that meets the requirements for high rigidity, long life and no preload loss during operation. In addition, friction losses in the bearing supports are reduced and transmission efficiency increases because the tapered roller bearings used previously have been replaced by an angular contact ball bearing.
Technical Paper
2003-05-19
Bager Ganemi, Rikard Mäki, Kent Ekholm, Richard Olsson, Bo Lundström
During the last years several electronically controllable automotive transmission systems, where wet clutches are used as intelligent differentials, have been developed. These applications generally apply high stress on the transmission fluids. The fluids must preserve the desired frictional characteristics at different torque level in an environment where the ambient and system temperature varies over a wide range. This paper is focused on limited-slip wet clutches in all-wheel-drive systems. Different approaches for transmission fluid development are described. Data from thermal analysis and friction measurements are used to illustrate the influence of system related parameters on frictional characteristics. The friction characteristics resulting from temperature changes on the surface of the lamella material is presented. It was found that the changes on friction characteristics and the negative trend of the friction curves are dependent on the increase of the temperature at the surface of the lamella material.
Technical Paper
2003-05-19
Rikard Mäki, Bager Ganemi, Richard Olsson, Bo Lundström
Part 1 of this paper is focused on requirements and evaluation methods for transmission fluids used to lubricate wet clutches in all-wheel drive systems. Part 2: Fluid Development and Verification; presents more measurement data and shows how these results are used in the fluid development process. The investigated all-wheel drive system, featuring a wet multi-plate clutch with a sintered brass base friction material, is described with emphasis on the demands placed on the transmission fluid. A new test equipment to determine the frictional (μ-V) characteristics of the transmission fluid is described. The equipment can measure the actual temperature experienced by the fluid in the contact zone using an infrared temperature measurement method, as well as temperature in the oil sump and inside the clutch discs by use of thermocouples. Variable operation parameters include velocity, normal force and oil flow.
Technical Paper
2001-03-05
Yoshitaka Hayashi, Makoto Zenbutsu, Hiroshi Suzuki
Regarding tapered roller bearings used on pinion shafts in differential gearboxes, it has been observed that some cases of bearing failure, like flaking or seizure, occurred much earlier than expected. As to the cause of this kind of failure, it has been clarified that on the shaft system supported by a pair of tapered roller bearings, the actual bearing load, including the preload of the bearings, fluctuates not only under the dynamic state but also under the static state because of the temperature distribution around the bearings. This fluctuation of the actual bearing load and preload greatly affects rolling fatigue life, seizure performance and the stiffness of the shaft support system. This paper discusses optimal design concepts for improving the rolling fatigue life, frictional torque, rigidity and seizure performance of a pair of tapered roller bearings. The design concepts are based on analysis results of the dynamic preload situation under actual operating conditions. Also introduced is a downsized shaft support system devised with a pair of tapered roller bearings developed using these design concepts.
Technical Paper
1998-11-16
Vladimir V. Vantsevich, Sergey V. Kharytonchyk, Gemunu S. Happawana, Osita D. I. Nwokah
Distribution of traction forces among driving wheels is one of the main factors governing the performance of a highway truck during acceleration and braking on varying macro and micro road surface conditions. Comprehension of the interaction between wheels and road surface provides a profound systematic way to simulate a truck's motion and design required components for the optimal performance. The development of electronic technologies has created the pre-conditions necessary to develop systems with controlled parameters. However, to realize the pre-conditions, vehicle dynamics problems have to be formulated and solved for both optimization and control. Many different approaches emerged with the aid of electronics to control the circumferential wheel forces (wheel torque) by restricting wheel slip. A part of such systems has been named as Acceleration Slip Regulation (ASR) and Anti Slip Differentials (ASD). In this paper, we develop a methodology for maximum ASR and ASD to meet challenging road conditions.
Viewing 1 to 30 of 57