Low-Voltage Switch Latching Mechanism for Reliable Contact Closing

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Low voltage switching devices often fail to complete the closing operation correctly when the actuation speed of the operating handle is too slow, leading to insufficient pressure on the contacts and potentially dangerous situations, and over-dimensioning the driving spring increases stress and costs.

Innovation Solution

The introduction of a latching mechanism that ensures the energy of the driving spring is transmitted abruptly and optimally during the closing operation, independent of the actuation speed, allowing the main supporting and operating shaft to always have sufficient kinetic energy for proper contact pressing, without the need for over-dimensioned springs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the driving spring is over-dimensioned to ensure sufficient energy for closing operation, then the reliability of contact pressing is improved, but the mechanical stress on components and manufacturing costs increase

Engineering Contradiction:
Improvereliability of closing operationVSAvoidmechanical stress
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The patent applies the dynamics principle by introducing a latching mechanism that transforms the static energy storage in the driving spring into dynamic energy release. The mechanism includes a latching element that holds the driving spring in a pre-charged state during slow actuation, then abruptly releases the stored energy at the optimal moment to ensure sufficient kinetic energy for contact pressing, regardless of the actuation speed. This dynamic energy management resolves the contradiction by providing reliable contact pressing without requiring an over-dimensioned spring that would increase mechanical stress.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the operating handle is actuated slowly, then the ease of operation is improved, but the kinetic energy accumulated by the shaft becomes insufficient to complete the closing operation correctly

Engineering Contradiction:
Improveease of manual operationVSAvoidcompletion of closing operation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies the preliminary action principle by pre-charging the driving spring during the slow actuation phase and storing this energy in a pre-loaded state through the latching mechanism. The latching element engages with the driving lever to hold the spring in a compressed state, preparing the system in advance to deliver the necessary kinetic energy impulse. This preliminary energy storage allows the system to maintain reliability of closing operation completion even when the operating handle is actuated slowly, as the energy is prepared beforehand and released at the critical moment.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the latching mechanism is introduced to ensure abrupt energy transmission, then the reliability of contact pressing is improved, but the device complexity increases

Engineering Contradiction:
Improvecontact pressing reliabilityVSAvoidcomplexity of driving assembly
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the intermediary principle by introducing a latching element that acts as a mediator between the operating handle and the movable contact assembly. This latching element selectively engages and disengages to control the energy transmission path: it holds the driving spring in a pre-charged state during the approach phase, then abruptly releases it at the optimal moment to transfer kinetic energy to the movable contact assembly. The latching element serves as an intermediary that simplifies the overall control logic while ensuring reliable contact pressing, as it automatically manages the energy release timing without requiring complex control systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 ensures reliable and safe closing operations across varying actuation speeds, reduces mechanical stress and manufacturing costs, and allows for the use of less powerful actuators and less valuable materials, maintaining proper functioning and safety.

Implementation Method 1

a driving assembly (6) reversibly moving said movable contact assembly (4) following a movement of said operating assembly (5) from said open position to said closed position, said driving assembly comprising a kinematic chain (61) and at least a driving spring (62)

Methodology Applied
Scientific EffectElastic potential energy: Spring

Implementation Method 2

The introduction of a latching mechanism that ensures the energy of the driving spring is transmitted abruptly and optimally during the closing operation, independent of the actuation speed, allowing the main supporting and operating shaft to always have sufficient kinetic energy for proper contact pressing

Methodology Applied
Scientific EffectMechanical energy transmission: Mechanical Force

Data Source

PatentEP3557604B1A low voltage switching device
Publication Date: 2023.09.27 ABB SPA
  • EP3557604B1 patent drawingFigure 1
  • EP3557604B1 patent drawingFigure 2
  • EP3557604B1 patent drawingFigure 3

AI summary

A low voltage switching device comprising: one or more electric poles having one or more movable contacts and corresponding fixed contacts adapted to be coupled to or uncoupled from each other; a movable contact assembly comprising said mobile contacts and a main supporting and operating shaft reversibly movable between a first contact position, at which said movable contacts and said fixed contacts are uncoupled, a second contact position, at which said movable contacts and said fixed contacts are coupled, and a third contact position, at which said movable contacts and said fixed contacts are coupled and kept pressed; an operating assembly comprising a handle mechanism having a handle adapted to be reversibly moved by a user or a motor operated actuator (MOE) between a first, open, position and a second, closed, position; a driving assembly operatively connected to said operating assembly and to said movable contact assembly and comprising a kinematic chain and at least a driving spring, said driving assembly reversibly moving said movable contact assembly following a movement of said operating assembly from said open position to said closed position, and vice-versa. In the low voltage switching device said driving assembly comprises a latching mechanism which is operatively coupled to said operating assembly and to said movable contact assembly, said latching mechanism interacting with said movable contact assembly and latching it in said first contact position during a first phase of the movement of said operating assembly between said first, open, position and said second, closed, position, then unlatching said movable contact assembly when said operating assembly is in an intermediate position between said first, open, position and said second, closed, position, thereby allowing the quick passage of said movable contact assembly from said first contact position to said third contact position in which said movable contacts and said fixed contacts are coupled and kept pressed.