Bi-directional Overrunning Clutch for Drive Mode Switching
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Solution Overview
Problem
Current vehicle differential systems lack the ability to seamlessly switch between two-wheel drive and four-wheel drive based on traction needs, affecting fuel economy and wear on the vehicle, especially in conditions where four-wheel drive is not necessary.
Innovation Solution
A selectively engageable differential assembly that utilizes a ring gear with variable geometry, a bearing assembly, and an electromagnet to automatically switch between two-wheel drive and four-wheel drive by controlling torque transfer based on traction conditions, with a default four-wheel drive capability in case of power failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four-wheel drive is used continuously, then traction is improved, but fuel economy deteriorates and wear on the engine and drive train increases
Solution Approach 1:
The differential assembly dynamically switches between two-wheel drive and four-wheel drive modes based on real-time traction conditions. The overrunning clutch mechanism allows the system to transition from a static four-wheel drive configuration to a dynamic system that can disengage front wheel drive when not needed, optimizing fuel economy while maintaining traction capability when required.
Solution Approach 2:
The system uses the vehicle's own motion and traction conditions to automatically determine when four-wheel drive is needed. The overrunning clutch mechanism self-activates based on the rotational speed difference between the front and rear wheels, eliminating the need for external sensors or complex control systems to manage the drive mode switching.
2Reliability
If four-wheel drive is used continuously, then traction is improved, but wear on the engine and drive train increases
Solution Approach 1:
The differential assembly dynamically switches between two-wheel drive and four-wheel drive modes based on real-time traction conditions. The overrunning clutch mechanism allows the system to transition from a static four-wheel drive configuration to a dynamic system that can disengage front wheel drive when not needed, optimizing fuel economy while maintaining traction capability when required.
3Adaptability or versatility
If a selectively engageable differential assembly is added, then switching between drive modes is enabled, but device complexity increases
Solution Approach 1:
The patent combines the overrunning clutch mechanism with the differential assembly, merging two separate functions (clutch operation and differential action) into a single integrated unit. This eliminates the need for separate clutch mechanisms and control systems that would otherwise be required, reducing overall system complexity while maintaining the ability to switch between drive modes.
Solution Approach 2:
The overrunning clutch mechanism serves multiple functions simultaneously: it acts as a torque transfer device, a speed differential mechanism, and an automatic engagement/disengagement system. This multi-functionality eliminates the need for separate components for each function, reducing the overall complexity of the drive mode switching system.
4Extent of automation
If an electromagnet is used to control engagement, then automated control is improved, but reliance on external power increases
Solution Approach 1:
The system uses the vehicle's own motion and traction conditions to automatically determine when four-wheel drive is needed. The overrunning clutch mechanism self-activates based on the rotational speed difference between the front and rear wheels, eliminating the need for external sensors or complex control systems to manage the drive mode switching.
Solution Approach 2:
The overrunning clutch acts as a mechanical intermediary between the engine's power output and the drive wheels. It automatically engages or disengages based on the rotational speed differential between front and rear wheels, providing fail-safe four-wheel drive capability without requiring external power sources or electronic control systems.
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
Enables efficient switching between two-wheel and four-wheel drive modes to optimize fuel economy and reduce wear, while ensuring continued traction in slippery conditions without relying on external power for four-wheel drive operation.
Implementation Method 1
an electromagnet to automatically switch between two-wheel drive and four-wheel drive by controlling torque transfer
Data Source
AI summary
Certain embodiments of the present disclosure describe a differential assembly for allowing a vehicle to switch between two-wheel drive and four-wheel drive. The differential assembly includes a bearing assembly positioned between a race gear and output hubs. An armature plate is rotationally coupled to the bearing assembly and a clutch plate is positioned to engage the armature plate. A biasing member biases the clutch plate to engage the armature plate and allow the bearing assembly to transmit torque between the race gear and output hubs. When electricity is provided to an electromagnet, the electromagnet exerts a magnetic force on the clutch plate that is sufficient to overcome the bias of the biasing member so the clutch plate does not engage the armature plate and the bearing assembly does not transmit torque from the race gear to the output hubs.