Compact Gearbox With Reverse Torque Recirculation
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Solution Overview
Problem
The increasing number of speed ratios in gear transmissions to achieve better acceleration and fuel economy results in a larger transmission size, which is problematic for vehicle designers due to space constraints, and there is a need for a common transmission component to serve various vehicle types, including sports cars and off-road vehicles, requiring adaptable design options.
Innovation Solution
A constant mesh gearbox with a plurality of individually selectable forward and reverse speed ratios is designed, utilizing a casing with parallel rotational axes, gear wheel pairs, and sleeves as idlers to provide additional low speed ratios, allowing for compactness and flexibility in component placement, including the option for differential gears and alternative output locations.
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 vehicle performance is improved, but the transmission size increases which is problematic for vehicle designers
Solution Approach 1:
The gearbox is designed with a common base component structure that can serve multiple vehicle types (sports cars and off-road vehicles) by modifying features rather than creating entirely different transmissions. The same casing and basic gear train structure accommodates different speed ratio configurations through optional components.
Solution Approach 2:
The patent introduces an additional intermediate axis (making three intermediate axes total) to arrange gear wheels in a three-dimensional configuration rather than simple linear arrangement. This allows more speed ratios to be packed into a compact space by utilizing spatial dimensions efficiently.
2Adaptability or versatility
If a common base component is used to serve various vehicle types, then the design flexibility and cost are improved, but the ability to meet specific vehicle attributes may be limited
Solution Approach 1:
The transmission is divided into a common base component (casing, input shaft, output shaft, basic gear trains) and optional modular components (additional intermediate axes, differential gears, alternative output locations). This segmentation allows the base component to be manufactured once and then configured for different vehicle types by adding or removing specific modules.
3Productivity
If additional speed ratios are added to the transmission, then the vehicle performance is improved, but the device complexity increases
Solution Approach 1:
Multiple gear wheel pairs are arranged on shared intermediate axes, allowing several speed ratios to be controlled through a common set of shafts and synchronization mechanisms. The first and second intermediate axes each carry multiple gear wheels that can be engaged with the input shaft to provide different forward speed ratios.
Data Source
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AI summary
A constant mesh gear transmission has an input shaft (21, 22), two layshafts (31, 35) and an output shaft (23). Gear wheels are selectively connectable to shafts to provide forward and reverse speed ratios. Reverse speed ratio is via a sleeve (85, 86) of a reverse layshaft (35). The sleeve can also re-circulate torque to a forward layshaft (31) to provide an additional low forward speed ratio. Two sleeves and two additional low forward speed ratios are disclosed.