Shift Collar Cam Mechanism for AWD NVH Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power transfer units in all-wheel drive systems face challenges with noise, vibration, and harsh tactile feedback due to coupling and decoupling of rotating shafts, which existing disconnect mechanisms fail to adequately address.
Innovation Solution
A disconnect assembly featuring a cam and cam follower with inclined cam surfaces and a shock absorbing device, allowing for controlled axial movement and dampening of impact forces, enabling smooth engagement and disengagement of shafts while reducing noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a disconnect device is used to uncouple shafts, then energy efficiency is improved by preventing power transfer to rear wheels when not needed, but noise and vibration increase during engagement and disengagement
Solution Approach 1:
The patent applies beforehand cushioning by incorporating a cam mechanism with a curved surface that gradually engages and disengages the disconnect shaft. The cam's inclined surface allows the shaft to be gradually pushed into or out of engagement rather than sudden coupling, cushioning the transition and reducing impact forces that generate noise and vibration. This resolves the contradiction by maintaining energy efficiency through reliable disconnect functionality while minimizing harmful noise and vibration during the engagement/disengagement process.
2Ease of operation
If a cam mechanism is used to move the shift collar, then engagement control is improved, but device complexity increases
Solution Approach 1:
The patent applies spheroidality by using a cam mechanism with a curved cam surface instead of a linear or flat engagement surface. The curved geometry of the cam allows for controlled axial movement of the shift collar through rotational motion, providing smooth and progressive engagement control. This curved approach improves ease of operation by enabling precise control over the engagement process while the compact cam design minimizes the added complexity compared to more elaborate actuation systems.
3Adaptability or versatility
If the collar is made movable to couple shafts, then adaptability is improved for selective power transfer, but harsh tactile feedback increases
Solution Approach 1:
The patent applies the intermediary principle by introducing a cam mechanism as a mediator between the actuator and the shift collar. The cam's curved surface acts as an intermediary element that transforms the actuator's motion into controlled axial movement of the shift collar, which then couples or decouples the shafts. This intermediary cam mechanism softens the interaction, reducing harsh tactile feedback during engagement while maintaining the adaptability for selective power transfer between front and rear wheels.
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 effectively minimizes noise and vibration by controlling the axial movement of the cam follower and collar, ensuring smooth operation and energy efficiency by selectively driving the output shaft only when needed, thus reducing energy wastage.
Implementation Method 1
The shock absorbing device may limit travel of the collar toward and into its engaged position and also damp or lessen impact forces
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
In at least some implementations, a disconnect assembly for a power transfer unit includes a cam and a cam follower. The cam is driven for rotation and has a cam surface that is inclined relative to an axis of rotation and a void spaced from the cam surface. The cam follower has a cam engagement surface and is arranged to be engaged by the cam surface so that the cam follower is displaced axially during at least a portion of the rotation of the cam. One or both of the cam and the cam follower includes an interface surface provided at an angle to the axis of rotation to control axial movement of the cam follower during at least a portion of the rotation of the cam when the cam surface is not engaged with the cam engagement surface.