Transfer Case Dual Drive Gear Automation
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Solution Overview
Problem
Current electronic shift on the fly transfer cases for vehicles lack efficient mechanisms for seamless shifting between two-wheel and four-wheel drive modes, as well as high and low range drive modes, often requiring complex and costly solutions that are not fully automated or adaptable.
Innovation Solution
A transfer case design featuring an input shaft with concentric and offset output shafts, a dual drive gear interposed between range and mode shifters, and a reversible electric motor with an electronic control unit to automate shifting between drive modes, utilizing a dual drive gear that rotates in both directions to actuate range and mode shifters, and a gear train to drive the dual drive gear in a clockwise and counterclockwise direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a complex electronic control system is used to automate shifting between drive modes, then the extent of automation is improved, but the device complexity increases
Solution Approach 1:
The patent combines the range shifter and mode shifter into a single integrated mechanism. The dual drive gear serves both functions simultaneously - rotating clockwise to shift between high/low ranges via the first cam, and rotating counterclockwise to engage four-wheel drive via the second cam. This merging of functions into a single mechanism reduces the number of separate components and control systems needed, thereby reducing device complexity while maintaining full automation capability.
Solution Approach 2:
The dual drive gear is designed as a multi-functional component that performs multiple shifting operations. A single gear rotation in either direction actuates both the range shifter (through the first cam and shift fork) and the mode shifter (through the second cam and synchronizer). This universal component eliminates the need for separate actuators and control mechanisms for each shifting function, reducing overall system complexity while achieving complete automation of all drive mode transitions.
2Reliability
If separate mechanisms are used for range shifting and mode shifting, then the reliability of each function is improved, but the device complexity increases
Solution Approach 1:
The patent merges the range shifter and mode shifter into one integrated mechanism centered on the dual drive gear. The first cam with its groove guides the shift fork for range changes, while the second cam guides a separate shift fork for mode changes. Both cam mechanisms are actuated by the same dual drive gear rotation, combining multiple functions into a single reliable mechanism rather than requiring separate independent systems.
Solution Approach 2:
Within the integrated dual drive gear mechanism, the patent segments the functions into distinct cam profiles. The first cam has a specific groove geometry for controlling range shift timing and sequence, while the second cam has a different groove geometry for controlling mode shift timing. This segmentation of functions within a unified mechanism allows each function to operate reliably with its own optimized control path while sharing the common actuation source.
3Device complexity
If manual shifting is used between drive modes, then the device complexity is reduced, but the ease of operation deteriorates
Solution Approach 1:
The transfer case is equipped with an electronic control system that automatically manages all shifting operations between two-wheel drive, four-wheel drive, high range, and low range modes. The control unit receives driver input (such as mode selection signals) and autonomously actuates the dual drive gear in the appropriate direction and timing to achieve the desired mode change. This self-service automation eliminates the need for manual manipulation of shift levers or cables, greatly improving ease of operation while the integrated mechanism keeps overall device complexity manageable.
Data Source
AI summary
A transfer case comprising an input shaft and a first output shaft sharing a primary axis of rotation; a second output shaft offset from the first output shaft; a range shifter comprising a first cam constructed and arranged to selectively shift a vehicle to a high-range drive mode, a low range drive mode, or a neutral drive mode; a mode shifter comprising a second cam constructed and arranged to actuate a synchronizer which selectively shifts the vehicle between a two-wheel drive and a four-wheel drive mode; and a dual drive gear interposed between the range shifter and the mode shifter which is rotatable to actuate the first cam and the second cam.