Tap Changer Indexing Gear Train With Cam-Roller End Position Lock
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Solution Overview
Problem
Existing indexing transmissions for on-load tap changers face challenges in preventing movement beyond end positions, leading to potential damage, and require complex mechanical means for reliable end position blocking, especially when dealing with independently movable Maltese wheels.
Innovation Solution
The proposed indexing transmission employs cam disks with rotatably mounted rollers that engage with a drive output disk, allowing for stepped rotation of a switch shaft through a defined step angle, utilizing a roller pair with convex and concave cam sections to minimize friction and ensure reliable indexing without jamming, using a roller lock instead of a friction lock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical end position blocking means are used to prevent movement beyond end positions, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent employs cam disks with convex and concave cam sections instead of traditional mechanical blocking means. The curved cam profiles guide the rollers through controlled engagement and disengagement, providing reliable end position blocking through geometric constraints rather than complex mechanical linkages. This curvature-based approach simplifies the overall device structure while maintaining high reliability in preventing over-travel.
2Reliability
If traditional Maltese wheel transmission is used, then indexing function is achieved, but friction and jamming risk increase
Solution Approach 1:
The invention replaces the traditional Maltese wheel with a cam disk featuring convex and concave curved sections. Rollers engage with these cam profiles, rolling along the curved surfaces to transfer motion. This curved engagement minimizes sliding friction compared to the traditional Maltese wheel's pin-and-slot mechanism, reducing energy loss and the risk of jamming while maintaining reliable indexed positioning.
Solution Approach 2:
The patent substitutes the classic Maltese wheel mechanical transmission with a cam-roller mechanism. Instead of using a Maltese wheel with radial slots and pins, the invention employs cam disks with specific profile curves that work with rollers. This substitution reduces frictional losses and improves reliability by eliminating the jamming-prone pin-slot engagement of traditional Maltese wheels.
3Loss of energy
If rollers are used instead of friction lock, then friction loss is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The cam disks feature carefully designed convex and concave curved sections that guide the rollers through precise engagement paths. These cam profiles are engineered to provide the necessary motion control and positioning accuracy. While manufacturing precision is required for the cam profiles, the rolling contact geometry inherently compensates for minor variations, maintaining low friction and reliable operation.
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 provides a reliable, low-friction, and easy-running indexing function that precisely fixes the driven element in a defined angular position, reducing the risk of jamming and enabling precise switching without appreciable friction, allowing for customizable drive output angles and translation ratios.
Implementation Method 1
the engagement elements are formed by respective rollers rotatably mounted at an end face near the outer edge of the disk and rolling on the outer edge of the at least one cam disk by a corresponding engagement profile with convex and concave cam sections
Data Source
AI summary
An indexing transmission for an on-load tap changer or a tap selector of a tapped transformer has a rotatable cam disk having an outer edge formed with a succession of convex and concave cam formations in regular succession and merging with one another, a crank transmission driving the cam disk, and a drive output disk acted on by the cam disk and having an outer edge. Engagement rollers rotatable on an end face of the drive output disk near the outer edge of the drive output disk roll on the outer edge of the cam disk. A switch shaft is rotationally fixed to the drive output disk such that the cam disk in cooperation with the engagement rollers of the drive output disk triggers a stepped rotation of the switch shaft through a defined step angle.