Vehicle Transmission Layout for More Gears Without Added Length
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Solution Overview
Problem
Conventional transmissions in heavy-duty vehicles become longer, heavier, and more expensive when additional gears are added to accommodate down-speeding engines, leading to weakened shafts and increased deflection under load, while also requiring additional housing modules and limited reverse gear ratios.
Innovation Solution
A transmission design featuring an input shaft, main shaft, countershaft, and reverse shaft with multiple gear planes and gearwheels, allowing for additional gear ratios without increasing length, including multiple reverse gear ratios, achieved through a splitter-type configuration with primary and secondary gear planes and a reverse shaft with selectively connectable gearwheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional gears are added to the transmission to accommodate down-speeded engines, then gear ratio coverage is improved, but transmission length increases
Solution Approach 1:
The patent utilizes a three-dimensional spatial arrangement with two primary gear planes stacked vertically, allowing multiple reverse shaft gearwheels to be positioned at different heights and radial locations. This dimensional organization enables multiple reverse gear ratios without extending the transmission length along the axial direction.
Solution Approach 2:
Multiple reverse shaft gearwheels are nested within the same transmission housing space, with gearwheels from different primary gear planes arranged in a compact configuration. The reverse shaft gearwheels are positioned to engage with corresponding input shaft gearwheels in a space-efficient manner, effectively nesting multiple gear transmission paths within a compact volume.
2Adaptability or versatility
If additional gears are added to the transmission, then gear ratio coverage is improved, but transmission weight increases
Solution Approach 1:
The reverse shaft serves multiple functions by carrying multiple reverse shaft gearwheels that provide different reverse gear ratios. This single shaft performs the work of what would traditionally require multiple separate reverse gear mechanisms, reducing overall transmission weight while maintaining multiple reverse gear capabilities.
Solution Approach 2:
Multiple reverse gear transmission paths are merged into a single integrated structure using one reverse shaft with multiple gearwheels. This consolidation eliminates the need for separate reverse gear mechanisms, reducing the total number of parts and overall transmission weight.
3Adaptability or versatility
If additional gears are added to the transmission, then gear ratio coverage is improved, but manufacturing cost increases
Solution Approach 1:
The transmission uses standardized gearwheel components across both primary gear planes, with similar mounting structures and engagement mechanisms. This homogenization of design elements simplifies manufacturing processes and reduces tooling costs compared to completely different reverse gear mechanisms.
Solution Approach 2:
The reverse shaft assembly with multiple gearwheels serves as a universal reverse gear mechanism that can provide multiple reverse ratios through a single integrated component set, reducing the total number of parts that need to be manufactured and assembled.
4Adaptability or versatility
If shaft length is increased to accommodate additional gears, then gear ratio coverage is improved, but shaft strength decreases
Solution Approach 1:
The patent transitions from a linear axial arrangement to a three-dimensional configuration with gearwheels positioned at different heights and radial distances. This allows the reverse shaft to maintain a compact length while still accommodating multiple gear engagement points through vertical and radial spacing.
Solution Approach 2:
Multiple gearwheels are nested within a compact shaft length, with gearwheels from different primary gear planes arranged in a space-efficient configuration that minimizes the required shaft length while maintaining structural integrity.
Data Source
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AI summary
A transmission (120) for a vehicle, comprising: - an input shaft (1), a main shaft (2), and a countershaft (3), the main shaft being coaxial with the input shaft and the countershaft being parallel therewith, - first and second primary gear planes (P1, P2) arranged for torque transfer between the input shaft and the countershaft, - at least one secondary gear plane (S1, S2, S3) arranged for torque transfer between the countershaft and the main shaft. The transmission further comprises a reverse shaft (4) arranged in parallel with the main shaft, wherein the first primary gear plane comprises a first reverse shaft gearwheel (41) arranged on the reverse shaft, and wherein the second primary gear plane comprises a second reverse shaft gearwheel (42) arranged on the reverse shaft, the second reverse shaft gearwheel being selectively rotationally connectable to the first reverse shaft gearwheel so as to engage a reverse gear of the transmission.