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Technical Paper

Fundamental Physics Behind New Suspension Concept for Automobiles

2000-05-01
2000-01-1647
The Transverse Leaf suspension with Superior Roll Axis is a new suspension concept for automobiles. It enables the load transfer during a turn to be more evenly redistributed between the two wheels on the same axle thus optimizing its tires lateral force capabilities. The TLSRA concept is made up of a single transverse leaf spring linking the middle of the sprung mass to the outer end of 2 transverse suspension arms per axle. Those transverse arms are mounted close to the middle of the sprung mass with their attachment points located above the mass centroïd. Each wheel assembly is mounted directly onto the free end of its respective suspension arm. Because body roll is now counteracting vertical load transfer during transient and permanent operating conditions, this suspension enables designers to keep spring stiffness low without compromising road handling.
Technical Paper

Improving the Ride & Handling Qualities of a Passenger Car via Modification of its Rear Suspension Mechanism

2000-05-01
2000-01-1630
This paper presents the results of a recent project of IKCo’s research center to modify the Paykan 1600’s rear suspension mechanism with the purpose of improving the car’s comfort, stability and handling qualities. The car was originally equipped with a solid rear axle with leaf springs. By replacing the original mechanism with a three-link mechanism with panhard bar and coil springs, the ride comfort and handling characteristics of the car were noticeably improved.3-D, nonlinear ride and handling models were developed and analyzed to determine the important kinematics and dynamic effects of the new mechanism on vehicle responses. To verify the analytical results, subjective tests were carried out on the vehicle. The results of these tests demonstrated remarkable improvement of the dynamics behavior of the car.
Technical Paper

Investigation of Package Bearings to Improve Driveline Performance

2000-06-19
2000-01-1785
The tapered roller bearings employed in axle centers for the pinion support are critical components in determining the noise, fuel economy and reliability characteristics of the vehicle. They represent a relatively complex mechanical and tribological system, with special requirements from the stiffness, lubrication and heat transfer points of view. This paper brings a contribution to the investigation of the intricate dependency between design parameters, environmental factors and the resultant performance of a package bearing in an integral double cup configuration. Axial compactness, reduced weight, and superior rigidity are only few of the multiple advantages recommending this type of double row bearings for automotive driveline applications. Different aspects related to the tapered roller bearing setting are analyzed in a theoretical and experimental manner, also under the consideration of the manufacturing and assembly processes.
Technical Paper

New Traction-Optimized Front Axle Limited-Slip Differential for AWD All-Terrain-Vehicle

2000-03-06
2000-01-1155
An advancement in All-Terrain-Vehicle (ATV) traction control has entered the market place with the debut of the 1999 Bombardier Traxter. The basis for this is the progressive front axle limited-slip differential. The Visco Lok‚ differential provides a speed-sensing progressive traction-optimized characteristic for maximum off-road performance. This paper includes an overview of the vehicle driveline system, functional characteristics of the differential, and torque transfer requirements.
Technical Paper

Rheological Properties Affecting the Fuel Economy of Multigrade Automotive Gear Lubricants

2000-06-19
2000-01-2051
The paper highlights the use of a light duty axle efficiency test for evaluating the fuel economy performance of automotive gear lubricants. Both final peak axle temperatures and torque efficiencies are recorded for several multigrade automotive gear lubricants. The dependence of temperature on torque efficiencies for the gear lubricants tested are discussed for a variety of driving conditions: city, highway and severe service. Temperature and torque efficiency data show strong dependence on additive system and viscosity- temperature characteristics of the gear lubricants under different driving conditions. A discussion of lubricant rheology and its importance to maintaining film strength for adequate bearing and gear lubrication as related to optimum torque efficiency and axle temperature under varying loads and pinion speeds is also provided.
Technical Paper

Estimation of fuel consumption and pollutant emissions of road vehicles by computer simulation and their validation by field measurements

2001-09-23
2001-24-0082
The paper concerns field measurements for validation of the simulation method VEMOSIM developed in Finland. The field measurements and their analyses were carried out in the following order: - Quantification of; - drive resistance coefficients by coasting; and - power train losses by acceleration; - Utilization of parameters quantified in computer simulation of fuel consumption; - Based on the drive resistance coefficients and power train losses one can use VEMOSIM and produce the fuel consumption amounts of vehicle drives on the test road sections, and finally; - Comparison of the results received from simulation with the ones received from field measurements. The test vehicle was a truck trailer combination with 7 axles and the mass was 61,060 kg. The simulated results (speed and fuel consumption) are in a very good agreement with the measured ones taking into account the inaccuracy of the input data of the road vertical alignment.
Technical Paper

Frequency Domain Sensitivity Analysis of Yaw Rate and Lateral Acceleration Response of Front Wheel Steering Vehicles

2001-01-10
2001-26-0035
A vehicle's lateral performance and handling characteristics are most important while negotiating a turn. In this paper sensitivity analysis of lateral acceleration and yaw rate for front wheel steering vehicles is carried out in the frequency domain using the first order standard and first order logarithmic sensitivity functions. A simple two degree of freedom model is used for deriving amplitude ratio and phase angle for both yaw rate and lateral acceleration. Vehicle mass, yaw moment of inertia, front and rear tire cornering stiffnesses and distance from the front axle to the centre of gravity are the design variables considered. This study predicts that the strongest parameter is the location of the centre of gravity and the weakest parameters are mass and yaw moment of inertia.
Technical Paper

Train Axle Detector Based on Signal Codification with a Barker code

2001-10-01
2001-01-3257
This paper presents the development and implementation of an electronic axle detection system applied to trains passing a predetermined point on a railway. The system permits detection even if the train is travelling at a velocity of up to 350 Km/h, depending on the diameter of the train wheel. The system uses two coils placed on either side of the rail, one used as an emitter and the other as a receiver, which, as a result of the attenuation of the electromagnetic field between the coils, detect the passing of the train wheel. In contrast to other systems with similar characteristics, in this case the signal emitted is specially coded (using a 13-bit Barker code). On reception, a correlation algorithm (implemented in an FPGA) enables the signal emitted to be detected even if there is a low signal-to-noise ratio. By using this technique, the system is also able to reject a great deal of interference coming from electric motors or other electromagnetic sources.
Technical Paper

Methodology for Accelerating Life Tests on Shock Absorbers

2001-03-05
2001-01-1103
Horizontal and vertical axle and cabin dampers are used on cars, trucks and busses to optimize the ride and safety and therefore represent vital components of the truck suspension. Nowadays there is a trend in industry for a longer component life featured by a shorter-term design. Therefore it becomes less obvious to have too many iterations in design with successive (long) durability test drives. Using the presented methodology the potential life damage for each critical component is identified from realistic road measurements and a life test is proposed which causes the same damage but in a relatively shorter period. This methodology was drawn up and validated during a European research program, Fatynamics.
Technical Paper

Optimization Methods for IRS Axle Mount Design

2001-03-05
2001-01-1158
Determination of locations and stiffness rates of Independent Rear Suspension (IRS) axle mounts is critical during the early stages of vehicle design. Depending on the vehicle, the design requirements of IRS axle mountings vary. Design objectives include the zero-roll condition, the static-roll condition and the dynamic-roll condition. Currently, there are no methods for IRS axle mount design for the dynamic-roll condition. Current design methods used for the other two requirements also lack accuracy and robustness. In this paper, methods developed for IRS axle mount design for all three objectives are explained. These methods are verified on a three-mount IRS axle. Additionally, placing the rigid body modes at desired frequencies is achieved. Compared to the current methods, the proposed methods are more accurate and robust. They could improve design quality and productivity significantly.
Technical Paper

A basic understanding of vehicle behavior in the stright-ahead motion

2000-06-12
2000-05-0283
In this paper, a simple vehicle model was investigated for the study of vehicle behavior in the straight-ahead motion. The vehicle model has two degrees of freedom without any suspension effect included. Through the analyses of the model with the various tire properties, we can explain how force and moment characteristics of the tires can cause lateral drift in the straight- ahead motion in free control mode. In the second part of the paper, a commercially available car was selected for the validity of the analyses. This car was modeled in detail with one of the multi-body dynamics simulation programs. The simulation results show that the amount of vehicle deviation from the intended straight path is directly related to a characteristic of the front axle tires, known as ATSP (Aligning Torque Static Phase).
Technical Paper

Dynamic Verification of the Effects of Varying the Inclination of the Inertia and Roll Axis in an Automobile

2000-06-12
2000-05-0228
The aim of the present study is to identify the effects produced by varying the inclination of the longitudinal inertia axis and the roll axis on the dynamics of an automobile. The objective is to find technically valid solutions to the optimisation of the vehicle in order to improve its handling behaviour and safety. Selected one of the cars available on the market, the ADAMS calculation code was used to create a multibody model of the car reproducing its dynamic behaviour. The model simulates in detail all the vehicle, including engine, front and rear suspension, brakes, steering line and tires. The experimental validation of the numerical model was performed comparing the analytical data with those measured at the Flat-Trac Roadway Simulator on a real vehicle in road configuration.
Technical Paper

Trailing Twist Axle Suspension Design Using ADAMS

2000-06-12
2000-05-0212
A twist beam plays important roles in a trailing twist axle suspension. The cross-sectional configuration of the twist beam determines the performance of the suspension. The finite element (FE) analysis is usually utilized in order to evaluate the performance of this suspension. However, most automotive designers cannot directly perform the FE analysis because specific skills are required to achieve sophisticated operation. Moreover, the construction of the FE model also requires a large amount of time and task. In this paper, we propose a new methodology for the initial design of the trailing twist axle suspension in order to overcome these problems. This method includes (1) the interactive drawing operation for the cross-section, (2) the quick evaluation of the cross-sectional properties, and (3) the automatic construction of the twist beam stiffness matrix used in the kinematic analysis.
Technical Paper

Turning characteristics of two-axle, four-wheel vehicle running on sandy soft terrain

2000-06-12
2000-05-0395
The objective of the research is to investigate the turning characteristics of a two-axle, four-wheel vehicle at steady-state circular turning on sandy soft terrain. The axle load, lateral force, thrust and effective tractive effort acting on the wheeled vehicle turning on soft and hard terrain were compared. It was observed that the directions of lateral force acting to the front wheel of vehicle running on soft and hard terrain are opposite. Moreover, the lateral force acting to front wheel of the case of vehicle running on soft terrain is larger than that for the case of hard terrain. However, it is found that there is only a little difference between lateral forces acting to rear wheel of vehicle running on soft and hard terrain. It was observed that the axle load of rear wheel was larger than that of front wheel running on soft terrain and the axial force-steering angle relationships of the soft and hard terrain were almost similar.
Technical Paper

Inertia Measurements of Large Military Vehicles

2001-03-05
2001-01-0792
This paper describes the design and operation of a facility for measuring vehicle center-of-gravity height; roll, pitch, and yaw moments of inertia; and roll/yaw cross product of inertia for a broad range of test specimens. The facility is configurable such that it is capable of measuring these properties for light, single axle trailers; long, heavy vehicles; and tank turrets. The design was driven by the need for accurate, repeatable measurement results and the desire to have a single facility capable of making measurements on a broad range of vehicle sizes.
Technical Paper

Roll-Down Process Development for Transmission Garage Shift Quality

2001-04-30
2001-01-1500
A roll down methodology has been developed to predict the driver's seat track fore-aft acceleration response using measured half shaft torque time histories and an analytically predicted vehicle sensitivity function suitable for transverse front wheel drive powertrains. The predicted vehicle sensitivity function (a frequency response function) relates the transmission torque applied to the drive axles to the seat track fore-aft acceleration. An experimental procedure was developed to measure the in-situ vehicle sensitivity function. The experimental data was used to correlate the analytical model. The testing results have shown that in the frequency range of the “garage shift” that the vehicle body can be represented as a rigid body. A Nastran model utilizing a rigid body representation of the body and powertrain is used to predict the vehicle response to the torque transient.
Technical Paper

The COANDA Flow Control and Newtonian Concept Approach to Achieve Drag Reduction of Passenger Vehicle

2001-03-05
2001-01-1267
In order to reduce total drag during aerodynamic optimization process of the passenger vehicle, induced drag should be minimized and pressure drag should be decreased by means of applying streamlined body shape. The reduction of wake area could decrease pressure drag, which was generated by boundary layer separation. The induced drag caused by rear axle lift and C-pillar vortex can be reduced by the employing of trunk lid edge and kick-up or an optimized rear spoiler. When a rear spoiler or kick-up shape was installed on the rear end of a sedan vehicle, drag was reduced but the wake area became larger. This contradiction cannot be explained by simply using Bernoulli’s principle with equal transit or longer path theory. Newtonian explanation with COANDA effect is adopted to explain this phenomenon. The relationships among COANDA effect, down wash, C-pillar vortex, rear axle lift and induced drag are explained.
Technical Paper

Understanding Oil Aging in Extended Drain Axle & Transmission Applications

2001-09-24
2001-01-3592
Extended drain of axle and transmission lubricants has gained wide acceptance in both passenger car and commercial vehicle applications. Understanding how the lubricant changes during extended drain operations is crucial in determining appropriate lubricants and drain intervals for these applications. A suitable aging screen test with an established relationship to field performance is essential. Over the years numerous methods have been studied (DKA, GFC, ISOT, ASTM L-60) with varying degrees of success1,2,3. Current methods tend to be overly severe in comparison to field experience, hence the need for further work in this area. As a result of recent work, a lubricant aging test method has been developed which shows good correlation with field experience, giving us an effective tool in the development of long drain oils.
Technical Paper

Comparison of Extended Service Lubricants for Heavy-Duty Transmissions and Axles

2001-09-24
2001-01-3595
Over the past several years, economic pressures have driven fleets to substantially increase their maintenance intervals. To meet this challenge, both the Original Equipment Manufacturers (OEMs) and the lubricant suppliers have developed new and better products to give fleet users the benefits of extended service intervals, while at the same time maintaining equipment life and providing the potential for reduced operating costs. Through the selection of proper lubricants, fleets can now minimize their total operating costs with products that meet the OEM extended service specifications, have demonstrated equipment durability, and are formulated using base oil and additive components to minimize the cost of the lubricant. This paper will examine the options available for formulating extended drain transmission and axle lubricants. It will explore the selection of the lubricant base oil as well as the additive system.
Technical Paper

Contribution to the Development of a Concept of Driving Mechanics for Commercial Vehicles

1983-02-01
830643
In the following essay, vehicle, and test stand related measuring and calculating methods will be introduced which have proven to be a suitable basis for the discussion of the criteria of driving mechanics for commercial vehicles (1 to 23). Because of the progress of electronics development these methods are reliable and quickly performed today. In connection with tire and brake characteristics, which are the basis for measuring driving maneuvers, and with the knowledge of axle and wheel movement, a purposeful and physically correct evaluation of the driving behavior of vehicles is possible. With the aid of complex mathematical vehicle substitution systems it is already possible to accurately estimate tendencies in the pre-development stage of a vehicle.
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