Groove Follower Crowning for Shift Drum Contact
Solution Overview
Problem
Existing groove followers in multi-step transmissions for motor vehicles do not optimally mate with shift drums, leading to damage and malfunctions due to improper contact points, resulting in increased wear and deformation, especially at high-load regions like synchronization and shift-through points.
Innovation Solution
The groove follower is designed with vertically and longitudinally crowned surfaces, aligning the guide curve with the active diameter of the shift drum to ensure central contact and reduced Hertzian pressure, minimizing wear and deformation, and allowing for the use of materials with lower strength requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a groove follower with constant height and planar surfaces is used, then the structure is simple and easy to manufacture, but the contact with the shift groove is uneven causing damage and rapid wear at high-load regions
Solution Approach 1:
The groove follower is equipped with crowned surfaces (vertical crowning and longitudinal crowning) that create different local contact characteristics. The vertical crowning ensures central contact on the groove flank, while the longitudinal crowning provides optimal contact along the active diameter, distributing pressure evenly and preventing localized damage and wear.
Solution Approach 2:
The groove follower incorporates curved crowned surfaces instead of planar surfaces. The vertical crowning creates a convex curvature in the vertical direction, and the longitudinal crowning creates a convex curvature in the longitudinal direction, enabling optimal contact patterns with the circular shift groove and reducing Hertzian pressure.
2Device complexity
If the groove follower contacts the lateral flanks above the active diameter, then the simple planar design is maintained, but damage and malfunctions occur due to uneven contact pressure
Solution Approach 1:
The crowned surfaces create localized contact zones that are optimized for different regions. The vertical crowning directs contact to the central region of the groove flank, while the longitudinal crowning ensures contact occurs at the optimal position along the active diameter, preventing contact above the active diameter that causes damage.
3Reliability
If crowned surfaces are added to the groove follower, then optimal contact patterns and reduced wear are achieved, but the manufacturing complexity increases
Solution Approach 1:
The invention modifies the geometric parameters of the groove follower by introducing vertical and longitudinal crowning with specific radii. These parameter changes optimize the contact characteristics and pressure distribution, achieving reliable operation with reduced wear despite increased manufacturing complexity.
Data Source
AI summary
A groove follower (70; 90) for cooperating with a shift groove (48) of a shift drum (44) of a multi-step transmission for a motor vehicle, the groove follower (70; 90) having a vertical crowning and a longitudinal crowning, and the shift groove (48) defining an active diameter along which the groove follower (70; 90) is to be guided in a state in which the groove follower (70; 90) engages into the shift groove (48), and the entirety of all the vertices (SHB) of the vertical crowning forming a guide curve (L) along the circumference of the groove follower, characterized in that the position of the vertices of the vertical crowning is selected such that the guide curve (L) corresponds essentially to the active diameter of the shift drum (44).(FIG. 5)