Positive Drive Differential With Overrunning Clutch for Wheel-Speed Split
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current four-wheel drive systems face challenges in maintaining optimal wheel speed during turns due to the inability of wheels on a common axle to rotate differentially, leading to premature wear and slippage, as existing differentials do not effectively manage torque distribution between the inner and outer wheels.
Innovation Solution
A positive drive differential assembly with a bi-directional overrunning clutch and pinion disconnect assembly, featuring a ring gear, roller clutch assemblies, and a linear actuator, allows independent rotation of wheels and controlled torque transmission, enabling the outer wheel to rotate faster than the inner wheel during turns while maintaining positive drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wheels are fixed to a common drive axle, then the drive system is simple and robust, but the wheels cannot rotate at different rates during turns causing slippage and wear
Solution Approach 1:
The drive system is segmented by introducing a differential mechanism that separates the rotation speeds of left and right wheels. The differential gear train divides the torque transmission path, allowing each wheel to rotate independently at different rates while maintaining a common drive source.
Solution Approach 2:
A differential mechanism acts as an intermediary between the common drive axle and the individual wheels. This intermediary component receives torque from the drive axle and distributes it to wheels that may be rotating at different speeds, resolving the conflict between unified power transmission and independent wheel rotation.
2Reliability
If a differential mechanism is added to permit differential rotation, then wheel slippage is reduced, but the device complexity increases
Solution Approach 1:
The differential mechanism automatically adjusts torque distribution between wheels based on their rotational speeds without external control. The internal gear geometry self-regulates to allow the faster-rotating wheel to take less torque while the slower wheel receives more, maintaining traction without requiring sensors or active control systems.
Solution Approach 2:
The differential mechanism changes the torque parameter dynamically based on wheel speed differences. When one wheel rotates faster than the other, the differential automatically alters the torque distribution ratio, providing more torque to the slower wheel to maintain traction while allowing the faster wheel to rotate freely.
3Productivity
If an overrunning clutch is used to manage torque distribution, then differential rotation is enabled, but the engagement and disengagement response time increases
Solution Approach 1:
The patent replaces traditional friction-based clutch mechanisms with a positive engagement mechanical system using splines and keys. This substitution eliminates slip during engagement and provides instantaneous torque transmission when the differential action is required, significantly reducing the response time compared to conventional clutch-based differentials.
Solution Approach 2:
The differential mechanism is pre-configured with engaged gear teeth and splined connections that are ready to transmit torque immediately when speed differential occurs. The mechanical components are positioned in advance to engage without delay, eliminating the engagement time lag associated with clutch actuation.
4Adaptability or versatility
If a disconnect device is added to control torque transmission to the secondary drive axle, then torque management is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The disconnect mechanism is merged with the existing differential housing and gear train structure. The same housing that contains the differential gears also incorporates the disconnect feature, eliminating the need for a separate disconnect device and reducing manufacturing complexity while maintaining torque transmission control capability.
Solution Approach 2:
The differential housing serves multiple functions: it contains the differential gear train, provides structural support, and incorporates the disconnect mechanism. This multi-functionality reduces the total number of components and simplifies manufacturing while providing both differential rotation control and torque transmission disconnection capabilities.
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 solution ensures reduced wheel slippage and wear by allowing independent wheel rotation, improving traction and reducing effort required for steering, while providing almost instantaneous engagement and disengagement of torque transmission.
Implementation Method 1
at least one spring biasing each roll against movement radially outward relative to the slot
Implementation Method 2
the rolls being biased by the spring into engagement with the contoured surface of the clutch housing
Data Source
Figure 1~2
Figure 3
Figure 4A~4C
AI summary
A positive drive differential assembly including a differential with an input pinion configured to operably engage with a drive shaft so as to permit the drive shaft to rotate the pinion. A bi-directional overrunning clutch assembly is configured to transmit torque between the pinion and two drive axle segments. A pinion disconnect assembly is provided for controlling transmission of rotation to the pinion and including a rotary coupler. A linear actuator is connected to the rotary coupler and configured to translate the rotary coupler between connected and disconnected positions.