Transmission Arrangement for Variable All-Wheel Drive Torque Distribution
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Solution Overview
Problem
All wheel drive motor vehicles face challenges in achieving efficient operation with regard to costs and installation space, particularly in enabling variable all wheel drive functions and brake force recovery while meeting fuel consumption and emissions standards.
Innovation Solution
A transmission arrangement comprising an additional drive unit, a planetary gear mechanism as the first transmission part region, and a differential gear mechanism as the second transmission part region, with a selector element that can be moved into three shifting positions to control the distribution of drive torque between the input and output elements, allowing for all wheel drive, recuperation, and 'disconnect' modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable all-wheel drive system with additional drive unit is implemented, then the adaptability and fuel efficiency are improved, but the device complexity and installation space increase
Solution Approach 1:
The patent combines the additional drive unit with the existing transmission system by integrating it into the planetary gear mechanism. The additional drive unit is coupled to the planetary gear set, allowing torque to be distributed to the rear axle while sharing structural components with the main transmission, thereby reducing overall system complexity despite adding variable AWD functionality.
Solution Approach 2:
The transmission arrangement is designed to perform multiple functions: it can operate in front-wheel drive mode, all-wheel drive mode, and recuperation mode. The planetary gear mechanism and additional drive unit work together to provide both torque distribution and energy recovery capabilities, making the system versatile while avoiding the need for separate dedicated systems.
2Use of energy by moving object
If brake force recovery (recuperation) is implemented, then energy efficiency is improved, but the device complexity increases
Solution Approach 1:
The recuperation function is merged with the existing planetary gear mechanism and additional drive unit. During braking, the system reverses the torque flow through the same planetary gears and electric machine used for torque distribution, enabling energy recovery without requiring a separate recuperation system and thus minimizing additional complexity.
Solution Approach 2:
The additional drive unit and planetary gear mechanism serve dual purposes: they distribute torque to the rear axle during acceleration and recover energy during braking. This multi-functionality allows the system to achieve both AWD and recuperation capabilities through a single integrated transmission arrangement rather than separate systems.
3Adaptability or versatility
If an electric rear axle is added for variable all-wheel drive, then the adaptability is improved, but the installation space and costs increase
Solution Approach 1:
The electric rear axle components are merged with the existing transmission housing and planetary gear mechanism. The additional drive unit is integrated into the transmission case, and the planetary gear set serves both the main transmission and the electric rear axle functions, thereby reducing the required installation space compared to a completely separate electric axle system.
Solution Approach 2:
The patent employs a nested arrangement where the planetary gear mechanism is integrated within the transmission housing, and the additional drive unit is coupled to the planetary gear set in a space-efficient manner. The compact planetary gear mechanism allows the additional drive components to be nested within the existing transmission envelope, minimizing the overall installation space requirement.
Data Source
AI summary
A transmission arrangement for the controllable distribution of a drive torque from an input element to at least one output element in an all wheel drive train of an all wheel drive motor vehicle, comprising an additional drive unit, a first transmission part region, the first transmission part region being drive-connected directly or indirectly to the additional drive unit, a second transmission part region, the first transmission part region being connected indirectly via the second transmission part region to the output element, and a selector element, it being possible for the selector element to be moved into three shifting positions, namely a first shifting position, in which the first transmission part region is drive-connected to the input element, a second shifting position, in which the first transmission part region is drive-connected to the second transmission part region, and a third shifting position, in which the first transmission part region is drive-connected neither to the input element nor to the second transmission part region.