Wheel Hub Epicyclic Reducer With Shiftable Direct Drive
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Solution Overview
Problem
Current epicyclic reducers in vehicles increase fuel consumption due to the need for higher engine speeds to achieve speed reduction, which is not efficient when torque demands are low, such as when the vehicle is unloaded.
Innovation Solution
An epicyclic reducer with a sprocket that can be shifted between a reduction position and a direct drive position, allowing the ring gear to be moved to direct drive when torque demand is low, eliminating wheel hub speed reduction and increasing fuel efficiency, and can be retrofitted using an existing pressurized gas system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If epicyclic speed reduction is provided at the wheel hub, then torque is increased and wheels rotate at lower speed, but fuel consumption increases due to higher engine speeds required
Solution Approach 1:
The patent applies a movable ring gear that can dynamically shift between two positions: engaged with planetary gears for speed reduction and disengaged for direct drive. This dynamic reconfiguration allows the system to adapt to varying torque demands, providing speed reduction only when necessary (e.g., during acceleration or heavy load) and direct drive during cruising or light load conditions, thereby optimizing fuel consumption while maintaining required torque output
2Force
If two-stage speed reduction is provided, then wheel rotational speed is reduced and torque increased, but device complexity increases
Solution Approach 1:
The patent integrates an epicyclic gear mechanism directly into the wheel hub assembly, combining the functions of speed reduction and torque multiplication within a single compact unit. The movable ring gear serves multiple functions: it acts as a gear element during reduction mode and as a locking element during direct drive mode. This multi-functional design achieves two-stage speed reduction capability without proportionally increasing overall device complexity
Solution Approach 2:
The epicyclic gear mechanism is nested within the wheel hub structure, with the sun gear, planetary gears, and ring gear arranged in a compact concentric configuration. The movable ring gear is positioned within the housing and can shift axially between engaged and disengaged positions. This nested arrangement minimizes space requirements and integrates the complex two-stage reduction mechanism into the existing wheel hub footprint
Data Source
AI summary
The invention relates to an epicyclic reducer for a vehicle hub that includes: a housing; a sun gear arranged in the housing that includes sun teeth and is configured for coupling to an input; a plurality of planet gears, each of which includes planet teeth meshed with some of the sun teeth; a planet carrier that couples the planet gears to each other and is configured as an output; and a ring gear that includes ring teeth meshed with some of the planet teeth of each of the planet gears. The ring gear can be moved within the housing between a reduction position in which the planet gears are configured to rotate relative to the ring gear, and a direct drive position in which the ring gear is constrained to rotate with the planet gears.