Three-Position Actuator Overrun Prevention via Zeneva Disc
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Solution Overview
Problem
Conventional three-position actuators for switchgear using a single drive shaft are prone to electric shortages or ground faults due to overrun, require high manual force for actuation, and generate noise from spring-based mechanisms, making them difficult to operate and potentially damaging.
Innovation Solution
A three-position actuator design featuring separate drive shafts for disconnecting and earthing switches, utilizing a zeneva disc with power transmission grooves and rollers to prevent overrun, and eliminating the need for spring-based elastic force, allowing for smooth and quiet operation with reduced manual force requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single drive shaft is used to actuate both disconnecting switch and earthing switch, then the device complexity is reduced, but the reliability deteriorates due to overrun causing electric shortage or ground fault
Solution Approach 1:
The patent divides the single drive shaft into two separate drive shafts: a first drive shaft for the disconnecting switch and a second drive shaft for the earthing switch. This segmentation allows independent control of each switch, preventing overrun issues while maintaining operational reliability. Each drive shaft can be precisely controlled to its required rotation angle without affecting the other switch.
2Productivity
If spring-based elastic force is used as supplementary driving source, then the productivity is improved by enabling automatic actuation, but the object-generated harmful factors worsen due to noise and component damage from collision
Solution Approach 1:
The patent replaces the spring-based elastic force mechanism with a direct motor-driven mechanical system. Motors are directly coupled to the drive shafts through gears, eliminating the need for springs. This substitution removes the collision between spring mechanisms and stoppers, thereby eliminating noise generation and preventing component abrasion and damage while maintaining full actuation capability.
3Reliability
If spring-based mechanism with stopper is used to limit displacement, then the reliability is improved by preventing overrun, but the ease of operation deteriorates due to high manual force required for actuation
Solution Approach 1:
The patent replaces the spring-based elastic force mechanism with a direct motor-driven mechanical system. Motors are directly coupled to the drive shafts through gears, eliminating the need for springs. This substitution removes the collision between spring mechanisms and stoppers, thereby eliminating noise generation and preventing component abrasion and damage while maintaining full actuation capability.
4Reliability
If separate drive shafts and zeneva disc mechanism are used, then the reliability is improved by preventing overrun, but the device complexity increases
Solution Approach 1:
The patent merges the control of both switches through a common zeneva disc mechanism. The zeneva disc receives rotational input from both the first and second drive shafts and converts it into precise angular positioning for the main shaft. This merging approach allows independent control of each drive shaft while achieving coordinated, precise positioning of both switches, preventing overrun without requiring completely separate control systems.
Data Source
AI summary
An actuator comprising: a disconnecting switch drive shaft; a first drive gear axially coupled to the drive shaft; a first follower gear in engagement with the first drive gear; a first drive disc having a first drive roller; a first rotary shaft axially supporting the first follower gear and the first drive disc; an earthing switch drive shaft; a second drive gear axially coupled to the earthing switch drive shaft; a second follower gear in engagement with the second drive gear; a second drive disc having a second drive roller; a second rotary shaft; a zeneva disc having a pair of groove portions which the first drive roller or the second drive roller is inserted into or separated from; and a main shaft for switching the disconnecting switch or the earthing switch in accordance with the rotation of the zeneva disc.