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Technical Paper

Motorcycle Toroidal CVT Design Concepts

2003-03-03
2003-01-0972
Although the toroidal continuously variable transmission (CVT) has been successfully introduced into the automotive market, it has not been developed for the motorcycle community even though manufacturers have shown interest. Further, little information is available with regards to their application in motorcycles. To aid in the development process, continuously variable toroidal transmission design concepts for a motorcycle application are presented. Alternate packaging configurations developed in this paper represent potential future motorcycle transmission arrangements. Variator design parameters and their effect on transmission operation are discussed. Both single and dual cavity designs as well as orientation of the engine and final drive are reviewed.
Technical Paper

Analysis of a Hybrid Multi-Mode Hydromechanical Transmission

2007-04-16
2007-01-1455
A multi-mode hybrid hydromechanical transmission (HMT) with infinite variability is designed to meet the power transmission needs of medium duty on- and off-road vehicles. A hydraulic pump-motor assembly provides output speed and torque variability in an input coupled split power configuration. Dual planetary arrangements with two multiplate clutches allow multi-mode ratio change and combination of power from the mechanical and variable branches of the power path. Hydraulic accumulators offer hydraulic power assist during launch conditions and storage of reclaimed energy during braking events. Transmission kinematic, force and power flow analyses will be developed for the HMT and analyzed for suitability in a bus application. The resulting benefits and areas for improvement will be discussed.
Journal Article

HMMWV Axle Testing Methodology to Determine Efficiency Improvements with Superfinished Hypoids

2013-04-08
2013-01-0605
A dynamometer test methodology was developed for evaluation of HMMWV axle efficiency with hypoid gearsets, comparing those having various degrees of superfinish versus new production axles as well as used axles removed at depot maintenance. To ensure real-world applicability, a HMMWV variant vehicle model was created and simulated over a peacetime vehicle duty cycle, which was developed to represent a mission scenario. In addition, tractive effort calculations were then used to determine the maximum input torques. The drive cycle developed above was modified into two different profiles having varying degrees of torque variability to determine if the degree of variability would have a significant influence on efficiency in the transient dynamometer tests. Additionally, steady state efficiency performance is measured at four input pinion speeds from 700-2500 rpm, five input torques from 50 - 400 N⋅m, and two sump temperatures, 80°C and 110°C.
Technical Paper

Development of Single Stage Input Coupled Split Power Transmission Arrangements and their Characteristics

2002-03-04
2002-01-1294
In recent years there has been an increased interest in the continuously variable split power transmissions as these drive units are capable of vehicle launches and directional changes without using clutches. These tasks are accomplished by appropriately splitting power between the fixed mechanical and variable ratio branches. The power is recombined at the transmission output. A properly designed split power transmission arrangement will improve vehicular agility and reduce variator size. This paper provides characteristics of six single stage input coupled continuously variable toroidal split power transmission arrangements. Mathematical equations are derived for speed, torque and power. A computer program that utilizes the capabilities of Matlab is developed. The program calculates the required fixed and variable branch gear ratios for the predefined variator, planetary and overall transmission ratios.
Technical Paper

Development of Dual Stage Input Coupled Split Power Transmission Arrangements and their Characteristics

2002-03-04
2002-01-0590
Continuously variable split power transmissions can offer a clutchless transition from reverse through neutral and into the forward driving mode. This is accomplished by splitting the input power between fixed ratio and variable ratio branches and recombining the power with a planetary set. Further, these transmissions offer seamless ratio changes throughout their range. In contrast to these benefits, single stage designs can suffer from recirculated power, which increases the power level through the variator. This results in the need for a larger variator, which reduces efficiency and increases weight and inertia. In addition, single stage designs can experience high planetary member speeds as a result of a wide transmission ratio range. Seven dual stage input coupled transmission models are developed in an effort to reduce the recirculated power and high planetary member speeds found in the single stage designs. Speed, torque and power models are developed in Matlab and Excel.
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