Non-Aligned Axis Constant Mesh Gearbox for Compact Vehicle Transmissions
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Solution Overview
Problem
The increasing number of speed ratios in gear transmissions for vehicles leads to larger transmission sizes, which is problematic for vehicle designers due to space constraints, particularly in in-line transmissions where it becomes difficult to integrate into the passenger compartment.
Innovation Solution
A constant mesh gearbox design with a non-aligned input and output axis, allowing for a wide and short transmission casing that provides six to eight sequential speed ratios with fewer gear wheels at higher ratios, reducing noise and enabling a low floor in the passenger compartment, and incorporating a sleeve for additional gearing options and torque flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of speed ratios is increased to achieve good acceleration and fuel economy, then the transmission performance is improved, but the size of the transmission increases which is problematic for vehicle designers
Solution Approach 1:
The patent transitions from a conventional in-line (North-South) transmission layout to a transverse (East-West) layout where the input and output axes are perpendicular rather than collinear. This dimensional change allows the transmission to fit within a smaller envelope volume while accommodating 6-8 speed ratios, effectively resolving the contradiction between increased productivity and reduced volume.
Solution Approach 2:
The transmission is segmented into distinct functional modules: a first gear set for lower ratios, a second gear set for higher ratios, and a revving up gear set for high-speed operation. This segmentation allows each module to be optimized independently and compactly arranged in the transverse layout, reducing overall transmission size while maintaining multiple speed ratios for improved acceleration and fuel economy.
2Adaptability or versatility
If in-line transmission is used with increased speed ratios, then more gear options are available, but ingress into the passenger compartment becomes difficult
Solution Approach 1:
By changing from an in-line arrangement to a transverse arrangement with perpendicular input and output axes, the transmission footprint in the longitudinal direction is reduced. This allows the transmission to be positioned lower and further forward, improving passenger compartment ingress while maintaining 6-8 gear options through the segmented gear sets.
3Ease of manufacture
If a common base component is used for range of vehicles, then manufacturing cost is reduced, but features must be added or deleted to suit particular attributes
Solution Approach 1:
The transverse transmission design with its modular segmented gear sets serves as a universal base component that can be adapted for multiple vehicle types. By selectively engaging different gear sets (first, second, or revving up), the same transmission can provide different ratio ranges suitable for sports cars, off-road vehicles, or conventional passenger vehicles, reducing manufacturing costs while minimizing the need for complex feature modifications.
Data Source
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AI summary
A constant mesh gearbox has five parallel rotational axes. The input and output axes are not aligned. Some torque paths are via a sleeve rotatable on a shaft on one of said axes. Up to eight forward speeds are disclosed, with two very low ratios suitable for non-highway travel. The transmission is suitable for two and four wheel drive.