Differential Transmission Range Splitter Mechanism
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Solution Overview
Problem
Four-wheel-drive vehicles face challenges in achieving a doubled range of transmission ratios without increasing complexity, cost, or bulk, especially when dealing with high forces in differential speeds, which can lead to weaknesses in guides and axial supports.
Innovation Solution
A range splitter mechanism integrated into the differential of a gearbox, featuring a two-part outer casing supporting the ring gear, with bearings in the gearbox casings, and a planetary gear train that includes a dog clutch sleeve for establishing two distinct gearbox ratios, allowing torque distribution between wheel drive shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an additional two-speed gearbox is included to provide additional range of speeds, then the gear ratio range is doubled, but the device complexity, cost, and weight increase significantly
Solution Approach 1:
The patent merges the range-doubling function with the differential assembly by integrating a planetary gear mechanism directly into the differential housing. This combination eliminates the need for a separate two-speed gearbox, reducing device complexity while maintaining the ability to provide two distinct gear ratio ranges (high and low ranges). The planetary gear train is coaxially arranged with the differential, sharing common mounting structures and support bearings.
Solution Approach 2:
The differential assembly is designed to perform multiple functions: it distributes torque to the drive wheels and simultaneously provides range doubling through the integrated planetary gear mechanism. The same housing and support structures serve both the differential function and the range-doubling function, making the system more versatile without proportionally increasing complexity.
2Adaptability or versatility
If the reduction gear is positioned at the gearbox input to provide additional range, then the gear ratio range is doubled, but the structure becomes heavier and more expensive due to required reinforcement
Solution Approach 1:
Instead of adding the reduction gear in series at the gearbox input (one-dimensional addition), the patent places the planetary gear mechanism in parallel within the differential assembly. This spatial reconfiguration allows the range-doubling function to be achieved without requiring reinforcement of the gearbox input structures, thereby reducing the additional weight that would result from structural reinforcement.
3Volume of moving object
If a range doubler mechanism is integrated into the differential, then the bulk is reduced and shaft integrity is preserved, but the guides and axial supports are subjected to high stresses under differential speeds
Solution Approach 1:
The patent introduces intermediary support elements within the differential assembly to mediate the high stresses experienced by the guides and axial supports. These intermediaries distribute the loads more evenly across the support structures, reducing peak stresses while maintaining the compact integrated design. The intermediary supports act as load-path modifiers that protect the critical guidance surfaces from excessive differential speed stresses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides a compact, robust differential transmission device that doubles the range of gearbox ratios while maintaining shaft integrity and reducing bulk, enhancing traction and adaptability for four-wheel-drive vehicles without major gearbox modifications.
Implementation Method 1
a planetary gear train (100) that includes a sun gear (23), a ring gear (10c), and a planet carrier (14), allowing torque distribution between wheel drive shafts
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
Disclosed is a gear-splitting differential transmission device positioned between a multi-ratio gearbox and two drive wheels of the vehicle, comprising an outer case (10) which receives the gearbox torque and by means of an internal mechanism divides it among two wheel drive shafts; the outer case (10) further houses an inner case (14), which together with the outer case (10), a set of intermediate planetary gears (19) and a control element (30) forms a two-position planetary gear set (100), making it possible to obtain two ranges of ratios of separate gearboxes for driving the drive wheels, characterized in that the inner case (14) has a central cylindrical protuberance (14h) for guiding the side gear (23) of the planetary gear set (100).