Auxiliary Drive Module for Selective All-Wheel Drive
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Solution Overview
Problem
Existing all-wheel drive vehicle systems are complex and costly, making it impractical to offer all-wheel drive in relatively inexpensive vehicle platforms, particularly due to packaging issues and the need for modifications such as relocating the fuel tank or spare tire.
Innovation Solution
A vehicle drive train system featuring a primary powertrain, a first axle, and a drivetrain module with an auxiliary drive system that includes a compact electric motor and an overrunning clutch, allowing selective power transmission to a second set of wheels, which reduces complexity and cost while enabling all-wheel drive capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional all-wheel drive systems are used, then all-wheel drive functionality is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The all-wheel drive system is segmented into independent modules: a primary two-wheel drive platform and a separate auxiliary drivetrain module that can be selectively engaged. This modular approach allows the vehicle to maintain simple two-wheel drive operation under normal conditions while providing optional all-wheel drive capability when needed, thereby reducing overall system complexity while maintaining versatility.
Solution Approach 2:
The auxiliary drivetrain module serves multiple functions: it provides all-wheel drive capability when engaged, can operate independently as a secondary power source, and integrates with the existing primary powertrain. This multi-functionality allows a single added component to achieve all-wheel drive functionality without requiring a complete system redesign.
2Adaptability or versatility
If conventional all-wheel drive systems are used, then all-wheel drive functionality is achieved, but manufacturing and installation cost increase
Solution Approach 1:
By segmenting the all-wheel drive system into a separable auxiliary module rather than integrating it into the vehicle chassis from the beginning, the system can be manufactured as a standalone unit and installed only in vehicles requiring all-wheel drive capability. This reduces manufacturing costs for base models while providing optional all-wheel drive functionality.
Solution Approach 2:
The auxiliary drivetrain module uses simpler, more cost-effective components compared to conventional all-wheel drive systems. The system employs basic mechanical elements like chain drives and simple differential mechanisms rather than complex electronic control systems, thereby reducing manufacturing and installation costs.
3Adaptability or versatility
If wheel hub motors are used, then all-wheel drive capability is achieved, but wheel size and packaging space increase
Solution Approach 1:
Instead of integrating motors directly into the wheel hubs, the invention extracts the power source function and places it in a separate auxiliary drivetrain module mounted on the vehicle chassis. This extraction allows the use of smaller wheels while maintaining all-wheel drive capability, as the power transmission components are located outside the wheel assembly.
Solution Approach 2:
The system transitions from a wheel-integrated motor approach to a chassis-mounted module approach, effectively moving the power transmission system to a different spatial dimension. This allows better packaging efficiency where the auxiliary drivetrain can be mounted in available chassis space rather than constrained by wheel well dimensions.
4Adaptability or versatility
If conventional all-wheel drive systems are integrated into two-wheel drive vehicles, then all-wheel drive capability is achieved, but vehicle architecture complexity increases
Solution Approach 1:
The vehicle architecture is segmented into a primary two-wheel drive system and an optional auxiliary all-wheel drive module. This segmentation allows the vehicle to be manufactured and sold as a simple two-wheel drive platform, with the all-wheel drive capability available as an optional add-on, thereby avoiding the need to redesign the entire vehicle architecture for all-wheel drive.
Solution Approach 2:
The system transitions from a static all-wheel drive architecture to a dynamic, selectively-engaged architecture. The auxiliary drivetrain module can be engaged or disengaged based on driving conditions, allowing the vehicle to operate in two-wheel drive mode during normal conditions and switch to all-wheel drive mode when needed, thereby reducing overall system complexity while maintaining versatility.
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 solution provides a cost-effective all-wheel drive system that can be integrated into vehicles without the need for extensive modifications, offering improved packaging flexibility and reduced manufacturing costs while maintaining all-wheel drive functionality.
Implementation Method 1
The overrunning clutch includes an input portion, which is coupled to the output shaft, and an output portion, which is coupled to the input shaft. The output portion is de-coupled from the input portion when a rotational speed of the input portion is not greater than a rotational speed of the output portion.
Data Source
AI summary
A vehicle with an axle assembly, which has a housing, a differential, an input shaft, a pair of shafts and a pair of wheel hubs, and an auxiliary drive unit that includes an electric motor and an overrunning clutch. The differential and the input shaft are disposed in the housing for rotation therein. The differential includes a case and a ring gear that is coupled to the case. The input shaft has a pinion that is meshingly engaged to the ring gear. Each shaft couples the differential to one of the wheel hubs. The clutch includes an input portion, which is coupled to the output shaft of the electric motor, and an output portion, which is coupled to the input shaft. The output portion is de-coupled from the input portion when a rotational speed of the input portion is not greater than a rotational speed of the output portion.