Twin Countershaft Transmission Spline Joint for Eccentric Load Relief
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Solution Overview
Problem
In heavy-duty transmission architectures, particularly in automated manual transmissions (AMTs) and dual clutch transmissions (DCTs), the buildup of tolerances between the main transmission shaft and the sun gear can lead to eccentric alignment, causing wear and premature failure due to radial displacement and misalignment of components.
Innovation Solution
The implementation of a 3×3×2 transmission configuration with a spline joint that provides radial clearance between the front and rear input shafts, allowing for proper torque transfer and reducing wear in bearings by accommodating misalignment and eccentric loads, while maintaining axial contact and balancing axial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the main transmission shaft directly engages with the sun gear of the planetary gear system, then power transmission is direct and efficient, but tolerance buildup causes eccentric alignment leading to wear and early failure
Solution Approach 1:
A spline connection is introduced as an intermediary element between the main transmission shaft and the sun gear. This spline connection includes radial clearance that accommodates misalignment caused by tolerance buildup, preventing direct engagement of the shaft with the sun gear while maintaining power transmission. The spline acts as a mediator that absorbs the eccentricity without transmitting it to the sun gear, thereby reducing wear and extending component lifespan.
2Manufacturing precision
If tight tolerances are maintained between the main transmission shaft and sun gear, then alignment precision is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The design changes the clearance parameter between the main transmission shaft and sun gear from a tight fit to a spline connection with radial clearance. This parameter change allows for tolerance buildup without requiring tight manufacturing tolerances, as the radial clearance in the spline connection accommodates the misalignment. This reduces manufacturing complexity while maintaining adequate alignment through the spline's inherent alignment capabilities.
Data Source
AI summary
A transmission includes a countershaft, a splitter section having an input shaft and a clutch that couples the input shaft to the countershaft, a main transmission assembly having a main shaft and a main transmission clutch, the main shaft coupled to the countershaft via the main transmission clutch, a range gear assembly having a an annulus gear, a sun gear, a planet gear, and center shaft that provides output from the transmission, and a spline joint that couples the main shaft to the center shaft and in operation transfers torque through and reduces eccentric loads between the main shaft and the center shaft that occur due to axial misalignment.