Two-Speed Active Transfer Case Packaging and Lubrication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current power transfer systems in four-wheel drive vehicles face challenges in packaging efficiency and lubrication management, particularly in smaller vehicles, where traditional active transfer cases require significant space and complex lubrication systems.
Innovation Solution
A two-speed active transfer case with a multi-plate friction clutch assembly and a splash recovery clutch lubrication system is integrated with the front output shaft, featuring a motor-actuated ballramp unit for clutch engagement control and a planetary gearset for range shifting, allowing for both manual and power-operated mode and range shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional active transfer case with friction clutch assembly is used, then torque transfer control is achieved, but packaging volume increases and lubrication system complexity increases
Solution Approach 1:
The patent combines the friction clutch assembly with the front output shaft, merging two previously separate components into one integrated unit. This integration eliminates the need for separate mounting space and reduces overall packaging volume while maintaining torque transfer control functionality.
Solution Approach 2:
The front output shaft is designed to serve multiple functions: it acts as both a rotational drive shaft and as the mounting structure for the friction clutch assembly. This multi-functionality reduces the number of separate components needed, thereby reducing packaging requirements.
2Reliability
If a shaft-driven lube pump is used for lubrication, then lubricant distribution is improved, but device complexity and weight increase
Solution Approach 1:
The transfer case utilizes its own operational motion to drive the lubrication system. The shaft-driven lube pump is powered by the rotation of the front output shaft itself, eliminating the need for external power sources or separate lubrication system controls. The system serves itself using its own operational energy.
Solution Approach 2:
The shaft-driven lube pump acts as an intermediary mechanism that converts the rotational motion of the front output shaft into pressurized lubricant flow. This mediator translates the existing mechanical energy into the required lubrication function without adding complex control systems.
3Power
If the friction clutch assembly is positioned on the rear output shaft, then torque transfer is effective, but packaging efficiency decreases
Solution Approach 1:
The patent relocates the friction clutch assembly from the rear output shaft to the front output shaft, utilizing a different spatial dimension and location within the transfer case. This repositioning optimizes the spatial arrangement of components, improving packaging efficiency while maintaining torque transfer effectiveness through the front driveline.
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 configuration enhances packaging efficiency, reduces complexity, and provides adaptive torque transfer while minimizing spin losses, weight, and noise, offering improved performance and reduced packaging requirements.
Implementation Method 1
a mode mechanism operably disposed between the transfer mechanism and the front output shaft, the mode mechanism configured as a friction clutch assembly
Implementation Method 2
A passive lubrication system utilizes lubricant splashed throughout the transfer case upon rotation of the sprockets to lubricate the rotary components and cool the clutch assembly
Data Source
AI summary
A two-speed active transfer case includes an input shaft adapted to receive drive torque from a powertrain, a rear output shaft adapted for connection to a rear driveline and aligned with the input shaft for rotation about a first rotary axis, a front output shaft adapted for connection to a front driveline and aligned for rotation about a second rotary axis, and a transfer mechanism driven by the rear output shaft. The transfer case also includes a two-speed range mechanism operably disposed between the input shaft and the rear output shaft, a range shift mechanism for controlling operation of the two-speed range mechanism, a mode mechanism operably disposed between the transfer mechanism and the front output shaft, and a mode shift mechanism for controlling operation of the mode mechanism.