Electrified Transfer Case With Axial Sleeve Mode Switching
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Solution Overview
Problem
Existing hybrid powertrains for four-wheel drive vehicles require significant modifications to the existing powertrain, leading to expensive and difficult packaging due to the integration of additional components, and lack additional operating modes.
Innovation Solution
An electrified transfer case with a mode selection device and controllable clutch system that allows for power distribution between front and rear axles, enabling various operating modes including electric-only, hybrid, generator, and neutral modes, while utilizing conventional powertrain components to minimize specialized packaging and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If significant modifications are made to the existing powertrain to integrate additional components, then hybrid functionality is achieved, but packaging difficulty and cost increase
Solution Approach 1:
The patent merges the hybrid powertrain control functions with the existing transfer case by integrating a mode selection device and controllable clutch system into the transfer case architecture. This combines multiple functions (power distribution, mode selection, torque transfer) into a single integrated unit, achieving hybrid functionality without adding separate dedicated components that would increase packaging complexity
Solution Approach 2:
The transfer case is designed to perform multiple functions: it serves as both a traditional power distribution device and a hybrid powertrain control unit. The mode selection device enables the transfer case to operate in multiple modes (two-wheel drive, four-wheel drive, electric-only, regenerative braking), making the existing component universal and eliminating the need for additional specialized packaging
2Adaptability or versatility
If significant modifications are made to the existing powertrain to integrate additional components, then hybrid functionality is achieved, but cost increases
Solution Approach 1:
By merging hybrid control functions into the existing transfer case, the patent eliminates the need for separate hybrid control components, reducing part counts and assembly operations. This integration approach leverages the existing manufacturing infrastructure for transfer cases, avoiding the need to develop new manufacturing processes for dedicated hybrid components, thereby controlling manufacturing costs
Solution Approach 2:
The multi-functional transfer case design allows the same component to serve traditional and hybrid functions, enabling manufacturers to utilize existing tooling, assembly lines, and supply chains for both conventional and hybrid vehicle production, thereby reducing development and tooling costs associated with creating entirely new hybrid-specific components
3Device complexity
If conventional powertrain components are used to minimize specialized packaging, then packaging complexity is reduced, but additional operating modes become unavailable
Solution Approach 1:
The patent incorporates a dynamically controllable clutch system within the transfer case that can selectively engage or disengage power flow paths based on operating conditions. This dynamic control capability enables the system to switch between multiple operating modes (2WD, 4WD, electric-only, regenerative braking) using the same conventional hardware, thereby achieving versatility without requiring specialized packaging for each mode
Solution Approach 2:
The mode selection device is integrated directly into the transfer case, allowing the power distribution system to automatically select and execute appropriate operating modes based on vehicle conditions without requiring external specialized control systems. This self-service capability enables multiple operating modes to be achieved through the existing transfer case architecture, avoiding the need for additional specialized packaging
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
The electrified transfer case provides flexible operating modes, reduces packaging complexity, and lowers costs by integrating with conventional powertrain components, offering enhanced functionality and efficiency in four-wheel drive vehicles.
Implementation Method 1
a gear set engaged to an electric motor for torque multiplication
Implementation Method 2
a controllable multi-plate clutch to selectively provide power to the second output shaft and front driveline
Data Source
AI summary
An electrified transfer case includes an input shaft, an output shaft, an electric motor, a gear reduction unit, and an axially moveable sleeve that is disposed axially between the input shaft and the output shaft. The sleeve selectively engages the input shaft, output shaft, and gear reduction unit based on the axial positon of the sleeve to selectively transfer power among the input shaft, output shaft, and electric motor. The sleeve is freely rotatable and supported on a support shaft that spans between and is freely rotatable relative to the input shaft and the output shaft. The sleeve includes multiple axially spaced clutch teeth. As the sleeve is controllably axially moved, different clutch teeth will engage with the input shaft, output shaft, and/or gear reduction unit to drivingly connect the components for operating in different modes, including EV, hybrid, conventional, generator, and neutral modes.