Extensible Rotation Transmission Shaft Preload Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional extensible rotation transmission shafts in steering devices suffer from rattling issues and guide plate damage due to bending deformation and repeated compressive and tensile loads, leading to wear and fatigue, especially when incorporated into vehicles as steering or intermediate shafts.
Innovation Solution
The extensible rotation transmission shaft incorporates an inner and outer shaft with axial balls, guided by inside and outside guide plates that are preloaded without relying on elastic forces, ensuring the balls are supported to prevent deformation and wear, with specific contact and non-contact areas to reduce stress on the guide plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a guide plate is provided between the outer surface of the inner-side concave groove and the rolling surface of each ball to suppress rattling, then the stability of the extensible rotation transmission shaft is improved, but the guide plate is damaged by fatigue due to high bending deformation and repeated compressive and tensile loads
Solution Approach 1:
A resin layer is introduced as an intermediary between the guide plate and the ball contact surface. This resin layer absorbs and distributes the repeated compressive and tensile loads, preventing direct transmission of high bending deformations to the guide plate, thereby suppressing fatigue damage while maintaining stability.
Solution Approach 2:
The contact interface parameters are changed by replacing direct metal-to-metal contact with a resin-based interface. The resin material properties (viscoelasticity, damping characteristics) are optimized to reduce stress concentration and bending deformation on the guide plate, preventing fatigue failure while maintaining operational stability.
2Reliability
If the guide plate is highly bending-deformed to preload the balls and suppress rattling, then the reliability is improved, but the guide plate is damaged by fatigue due to repeated loading
Solution Approach 1:
The resin layer serves as a mediator that maintains the preload function on the balls without requiring high bending deformation of the guide plate. The resin's compliant nature allows it to deform and maintain contact pressure while protecting the guide plate from fatigue damage, thereby extending service life while preserving reliability.
Solution Approach 2:
The resin layer provides beforehand cushioning by absorbing and dissipating repeated compressive and tensile loads before they can cause fatigue damage to the guide plate. This protective cushioning effect maintains reliability over extended service periods by preventing fatigue crack initiation and propagation.
3Force
If the guide plate is highly bending-deformed during torque transmission, then the rotational force transmission is improved, but the guide plate is damaged by fatigue due to repeated loading
Solution Approach 1:
The resin layer acts as an intermediary that transmits torque from the balls to the guide plate structure while reducing peak stress concentrations. The resin's viscoelastic properties allow it to accommodate torque fluctuations and reduce the magnitude of bending deformations on the guide plate, enabling effective torque transmission without fatigue damage.
4Ease of manufacture
If the guide plate structure is simplified to reduce manufacturing complexity, then the ease of manufacture is improved, but the guide plate cannot be supported properly and is damaged by repeated tensile deformation
Solution Approach 1:
The resin layer compensates for potential structural weaknesses in simplified guide plate designs by providing additional support and stress distribution. Even when the guide plate structure is simplified for ease of manufacture, the resin intermediary ensures proper load distribution and prevents repeated tensile deformation, maintaining reliability.
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 configuration effectively suppresses rattling and prevents damage to guide plates and wear on parts by preloading the balls using the elastic deformation of the shafts, maintaining structural integrity and reducing contact stress during axial displacement.
Implementation Method 1
at least the inner surface of the outer-side concave groove is elastically deformed more radially outwards than a state before the assembling, thereby preloading the respective balls
Implementation Method 2
the rolling surface of each ball and a radially outside surface of the inside guide plate contact each other only at two circumferentially set-apart inside contact parts
Data Source
AI summary
The rolling surface of each ball and a radially outside surface of the inside guide plate are in contact with each other only at two circumferentially set-apart inside contact parts. The rolling surface of each ball and a radially inside surface of the outside guide plate are in contact with each other only at two circumferentially set-apart outside contact parts. At a state after the extensible rotation transmission shaft is assembled, at least the inner surface of the inner-side concave groove is elastically deformed more radially inwards than a state before the assembling, thereby preloading the respective balls.