Research Papers

Designing a Hydraulic Continously Variable-Transmission (CVT) for Retrofitting a Rear-Wheel Drive Automobile

[+] Author and Article Information
Noah D. Manring

e-mail: ManringN@missouri.edu

Taha S. Al-Ghrairi

e-mail: alghrairi.taha@gmail.com
Mechanical and Aerospace
Engineering Department,
College of Engineering,
University of Missouri,
Columbia, MO 65211

Sean D. Vermillion

Mechanical Engineering Department,
College of Engineering,
Texas A&M University,
College Station, Texas 77843
e-mail: sdvermillion@tamu.edu

Contributed by the Power Transmission and Gearing Committee of ASME for publication in the JOURNAL OF MECHANICAL DESIGN. Manuscript received January 24, 2013; final manuscript received July 10, 2013; published online September 18, 2013. Assoc. Editor: Qi Fan.

J. Mech. Des 135(12), 121003 (Sep 18, 2013) (11 pages) Paper No: MD-13-1027; doi: 10.1115/1.4025119 History: Received January 24, 2013; Revised July 10, 2013

This research shows that an existing rear-wheel drive vehicle may be easily retrofitted with a continuously variable-transmission for the purposes of reducing the overall fuel consumption of the automobile. The retrofit-ability of this transmission is the primary advantage that it exhibits over other continuously variable-transmissions. By retrofitting this vehicle with the transmission components that are shown in this paper, the existing vehicle transmission continues to be used with the exception of the driveshaft which is replaced by the hydraulic continuously variable-transmission itself. Using a standard model for the vehicle dynamics, this paper presents a detailed analysis for the speed ratios of all gears, and shows how to specify the size of the hydraulic pump and motor to insure a safe pressure level of operation. To illustrate the usefulness of this method, an actual transmission is designed for the 1997 Ford Ranger, and the range of adjustability for the transmission is evaluated by seeking to hold the engine speed constant for a ramped speed output of the vehicle. In conclusion, this research shows that the design methodology is valid and that only minor errors in engine speed are observed during low ground velocities for the vehicle.

Copyright © 2013 by ASME
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Fig. 1

Schematic of the hydraulic continuously variable-transmission

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Fig. 2

Automobile schematic

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Fig. 3

Schematic of the compound spur gear

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Fig. 4

Schematic of the planetary gear

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Fig. 5

Partial free-body diagrams for the components within the planetary gear

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Fig. 6

Schematic of an example transmission design for a 1997 Ford Ranger (all dimensions are in millimeters)

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Fig. 7

A strip chart showing typical transmission results for a ramp increase in vehicle speed versus dimensionless time, t∧



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