Drivetrain Torque Reduction for Fuel Economy
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Solution Overview
Problem
Existing drivetrain systems for tractor-trailer vehicles face increased strain and component failure due to high torque levels when attempting to maintain lower engine RPMs for improved fuel economy, leading to reduced fuel efficiency under adverse conditions.
Innovation Solution
A vehicle drivetrain system featuring a rear end differential with gear ratios between 3.08-3.90 to 1 and a transmission with a final gear ratio of 0.47-0.63 to 1, which reduces torque in the driveline while maintaining lower engine RPMs, thereby improving fuel economy and extending component life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lower gear ratios (1.91-2.40 to 1) are used in the rear end differential to maintain lower engine RPM, then fuel economy is improved, but torque remains excessive in the drivetrain components causing broken u-joints and component failure
Solution Approach 1:
The invention segments the drivetrain system into two distinct components with specific functions: a rear end differential with lower gear ratio (1.91-2.40:1) for fuel economy, and a torque reducing mechanism (torque arm with bushing or torque reducer device) positioned between the differential and drive wheels to limit torque transmission to 80-90% of original levels, preventing component failure while preserving the fuel economy benefits of the lower gear ratio
Solution Approach 2:
The torque reducing mechanism acts as an intermediary element between the rear end differential and the drive wheels. This intermediary component (torque arm with bushing or torque reducer) selectively transmits only 80-90% of the torque from the differential to the drive wheels, thereby protecting drivetrain components from excessive torque while maintaining the lower engine RPM operation needed for improved fuel economy
2Reliability
If conventional transmission ratios and rear end gears are used, then drivetrain component strain is reduced, but engine RPM increases leading to higher fuel consumption under adverse conditions
Solution Approach 1:
The invention segments the drivetrain system into two distinct components with specific functions: a rear end differential with lower gear ratio (1.91-2.40:1) for fuel economy, and a torque reducing mechanism (torque arm with bushing or torque reducer device) positioned between the differential and drive wheels to limit torque transmission to 80-90% of original levels, preventing component failure while preserving the fuel economy benefits of the lower gear ratio
Solution Approach 2:
The invention changes the torque transmission parameter by introducing a torque reducing mechanism that limits torque transmission to 80-90% of the original level. This parameter change allows the system to use lower gear ratios (improving fuel economy) while the torque reduction compensates for the increased component strain, thereby resolving the contradiction between fuel consumption and component reliability
Data Source
AI summary
A drivetrain assembly for a motor vehicle such as a tractor-trailer rig wherein the drivetrain assembly includes a transmission and a rear end differential that have gearing operable to lower the operational engine RPM's of the vehicle. The transmission of the present invention includes a gearing ratio having a stepped percentage difference intermediate each gear. The final gear ratio of the transmission ranges between 0.47 to 1 and 0.63 to 1. A rear end gear ratio is present within the range of 3.08 to 1 to 3.90 to 1. The rear end gear ratio is approximately five and a half to six and a half greater than the ratio of the final gear of the transmission. The engine RPM's of the vehicle are at a lower RPM when the transmission is in its final gear or speed resulting in less fuel injection cycles and improved fuel economy.