Tap Changer Indexing Gear with Roller-Cam Step Locking
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Solution Overview
Problem
Existing indexing gears for on-load tap changers in tapped transformers face challenges in providing a reliable and low-friction stepping mechanism that prevents overrun and ensures precise positioning, as they often rely on complex mechanical locking systems that are not suitable for concentric Geneva wheels or result in significant friction.
Innovation Solution
A stepping mechanism utilizing cam disks with rotatably mounted rollers that engage with a driven disk, allowing for smooth and precise rotation with minimal friction, where the rollers roll on convex and concave curves to achieve defined step angles, and can be locked in desired positions using suitably contoured blocking curves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical locking means are used to prevent overrun in existing indexing gears, then reliability is improved, but device complexity increases and friction increases
Solution Approach 1:
The patent removes the separate locking disk and pawl mechanism from the system. Instead, the control disk itself integrates the stopping function through its contoured outer circumference that directly engages with rollers on the Geneva wheels, eliminating the need for additional locking components.
Solution Approach 2:
The control disk combines multiple functions: it drives the Geneva wheels through its contoured surface while simultaneously providing the stopping function through its outer circumference engagement with the rollers. This merging of driving and locking functions into a single component reduces overall device complexity.
2Reliability
If separate locking disk with pawl is used as in DE 10 39 129 A, then end position locking is achieved, but device complexity increases and it becomes unsuitable for concentric Geneva wheels
Solution Approach 1:
The control disk serves multiple purposes: it acts as a driving element for the Geneva wheels through its contoured surface and simultaneously functions as a locking mechanism through its outer circumference that engages with the rollers. This universal component works effectively for concentric Geneva wheels without requiring separate locking devices.
3Reliability
If traditional mechanical locking systems are used, then end position blocking is achieved, but friction increases and smooth operation decreases
Solution Approach 1:
The patent employs curved engagement surfaces throughout the mechanism. The control disk has a contoured outer circumference with convex and concave curve sections that engage with rollers, creating rolling contact rather than sliding contact. This curvature enables smooth operation with minimal friction while maintaining reliable positioning.
4Loss of energy
If convex and concave curve sections are used on cam disk, then rolling contact is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The control disk features convex and concave curve sections on its outer circumference that create rolling contact with the rollers. These curved surfaces are designed to provide smooth motion transmission while maintaining manufacturability through standardized contouring approaches.
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 mechanism provides a reliable, jam-proof, and low-friction indexing function, enabling precise angular positioning with minimal play, allowing for smooth operation and precise switching without significant friction, and can be customized for various output angles and transmission ratios.
Implementation Method 1
the engagement elements are each formed by rollers mounted rotatably on a flat side near the outer circumference of the disk, which roll with a corresponding engagement contour with convex and concave curve sections that follow one another regularly and merge into one another on the outer lateral surface of the at least one cam disk
Implementation Method 2
without any significant sliding movements with the associated friction effects occurring
Data Source
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AI summary
The invention relates to an indexing gear train (10) for an on-load tap changer or tap selector of a step transformer, wherein at least one cam disk (18; 20) driven by a crank mechanism (12) interacts with an output disk (22) having engagement elements (24) arranged on the output disk, the output disk being connected to a switch shaft (40) in a rotationally fixed manner, wherein the at least one cam disk (18; 20), in interaction with the engagement elements (24) of the output disk (22), triggers an incremental rotation of the switch shaft (40) by a defined increment angle. The engagement elements (24) are formed by rollers (26) rotatably supported on a flat side near the outer circumference of the disk (22). Said rollers roll with a corresponding engagement contour on the outer surface of the cam disk (18; 20), said engagement contour having convex and concave cam sections (30; 42) that regularly follow each other and transition into each other.