Transfer Case Layout for Four-Wheel Drive Power Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of an electric motor as a power source in four-wheel drive vehicles shifts the center location of the engine, transmission, and electric motor, making it impossible to position the propeller shaft in the floor tunnel due to the conventional layout of the transfer case.
Innovation Solution
A power transmission device where the transfer case is supported by a gear case, with the engine on one side and the electric motor on the other, featuring a transfer input shaft connected to the main drive wheels and a transfer output shaft connected to the auxiliary drive wheels via a propeller shaft, and a power transmission mechanism that changes the axis of rotation direction, allowing the transfer output shaft to be positioned at the vehicle's center and overlapping with the gear case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electric motor is added as a power source on the opposite side of the engine, then the power source configuration is improved for electrified vehicles, but the center location of the power transmission system shifts and the propeller shaft cannot be disposed in the floor tunnel
Solution Approach 1:
The transfer case is positioned in the longitudinal direction of the vehicle rather than being centered in the vehicle width direction, allowing the propeller shaft to extend forward to the transfer case while maintaining its ability to connect to the differential assembly. This dimensional repositioning resolves the conflict between having an electric motor on the opposite side and maintaining proper propeller shaft alignment.
Solution Approach 2:
The power transmission system adopts an asymmetric layout where the transfer case is positioned offset toward the electric motor side in the longitudinal direction, rather than being symmetrically centered. This asymmetric positioning allows the system to accommodate both the engine and electric motor while maintaining proper propeller shaft alignment through the floor tunnel.
2Device complexity
If the transfer case is positioned on the same side as the engine, then the layout is simple, but the transfer output shaft cannot be located at the center in the vehicle width direction when an electric motor is added
Solution Approach 1:
The transfer case is repositioned in the longitudinal dimension of the vehicle, extending forward from the gear case, which allows the transfer output shaft to be positioned centrally in the vehicle width direction while accommodating the electric motor on the opposite side of the engine.
3Area of stationary object
If the transfer case wraps around from the electric motor side to the rear surface, then space is created for steering system components, but the transfer case structure becomes more complex
Solution Approach 1:
The transfer case is designed as a separate component that wraps around from the electric motor side to the rear surface, creating distinct functional zones. This segmentation allows the transfer case to provide both power transmission functionality and create installation space for steering system components without requiring complete redesign of the entire power transmission system.
Data Source
AI summary
In a power transmission device of a four-wheel drive electrically driven vehicle, the power source includes a transverse engine supported on one side surface of a gear case, and a motor supported on the other side surface. A transfer case is supported on the same side surface of the gear case as the motor. The transfer case has a transfer input shaft arranged in the vehicle width direction, a transfer output shaft arranged in the longitudinal direction of the vehicle, a bevel gear pair and a transfer gear pair. The bevel gear pair and the transfer gear pair transmit power by changing a rotational axis direction to an essentially orthogonal direction between the transfer input shaft and the transfer output shaft. An output shaft gear provided on the transfer output shaft of the transfer case is disposed in a position overlapping the gear case in a vehicle width direction.