Elastic Lever Tripping Actuator for Low-Power Switching Reliability

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Solution Overview

Problem

Electromagnetic tripping actuators in residual current devices are sensitive to external magnetic fields and have poor impact resistance due to reliance on a small electromagnetic force, requiring a large tripping force that is difficult to achieve with low input power.

Innovation Solution

A tripping actuator with an elastic lever mechanism and a limiting block that accumulates and releases elastic potential energy, allowing a small motion stroke of the limiting block to trigger a large motion stroke of the rotating rod, enhancing sensitivity and resistance to impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If magnetic retention technology is adopted to reduce coil energy consumption, then energy efficiency is improved, but the permanent magnet becomes sensitive to external magnetic fields and impact resistance deteriorates

Engineering Contradiction:
Improvecoil energy consumptionVSAvoidimpact resistance
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent segments the force generation function into two parts: the elastic member (spring) provides the main retaining force against impact and external magnetic fields, while the electromagnetic coil only needs to provide a small triggering force to release the latch. This segmentation allows the coil to consume minimal energy (microvolt-ampere level) while the system maintains high impact resistance through the mechanical elastic member.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The elastic member is pre-compressed to store elastic potential energy before tripping is needed. The latch mechanism is pre-positioned to hold the armature in the closed state. When the coil is energized, it only needs to provide a small force to release the latch, allowing the pre-stored elastic energy to rapidly drive the tripping action. This preliminary preparation enables both low energy consumption and high response speed.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a large tripping force is provided to ensure reliable circuit disconnection, then tripping reliability is improved, but the coil input power requirement increases

Engineering Contradiction:
Improvetripping reliabilityVSAvoidcoil input power
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent uses a dynamic latch-release mechanism where the system transitions from a static held state (armature pressed against yoke by elastic force) to a dynamic release state. The electromagnetic coil dynamically switches the system from stable closed position to tripping state. This dynamic approach allows the coil to provide only momentary triggering power rather than continuous high power to maintain the tripping force.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The elastic member is pre-compressed during normal operation to accumulate potential energy. The latch is pre-positioned to maintain the closed state with mechanical advantage. When tripping is required, the coil only needs to provide sufficient energy to overcome the latch holding force, not the full tripping force. The pre-stored elastic energy then amplifies this small input into a large tripping force, achieving reliable disconnection with minimal coil power input.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If the armature is kept in contact with the yoke using magnetic difference, then sensitivity is improved, but the structure becomes vulnerable to external magnetic fields

Engineering Contradiction:
Improvetripping sensitivityVSAvoidexternal magnetic field sensitivity
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the electromagnetic magnetic-difference holding mechanism with a mechanical elastic holding mechanism. The elastic member (spring) mechanically presses the armature against the yoke to maintain the closed state, eliminating dependence on magnetic field strength. The electromagnetic coil's role is reduced to merely releasing a latch that holds the elastic member in its compressed state. This substitution makes the holding force insensitive to external magnetic fields while maintaining high tripping sensitivity through the mechanical latch-release design.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 enables fast, sensitive, and powerful tripping actions with high resistance to vibration and impact, even with low electromagnetic force input, by leveraging a mechanical trigger structure.

Implementation Method 1

In a lever swinging stroke, the elastic lever mechanism includes a first stroke of accumulating elastic potential energy and a second stroke of releasing the elastic potential energy

Methodology Applied
Scientific EffectElastic potential energy: Elasticity

Implementation Method 2

The electromagnetic RCD converts the residual current to a secondary side by using a transformer; an electromagnetic tripping actuator is driven by an output of the secondary side

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

When the tripper acts, the coil generates magnetic flux to reduce the magnetic flux of the permanent magnet in the 'permanent magnet working loop'

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Data Source

PatentEP4583142A1Switching appliance
Publication Date: 2025.07.09 XIAMEN HONGFA TRANSPORTATION ELECTRONICS CO LTD
  • EP4583142A1 patent drawingFigure 1
  • EP4583142A1 patent drawingFigure 2~3
  • EP4583142A1 patent drawingFigure 4~5

AI summary

The present disclosure relates to a switching appliance including a tripping actuator (100). The tripping actuator (100) includes an elastic lever mechanism and a limiting block (2) and can approach or go away from the elastic lever mechanism. The limiting block (2) laps the elastic lever mechanism by approaching the elastic lever mechanism and keeps it in a state of accumulating elastic potential energy, and releases the elastic lever mechanism by going away from the elastic lever mechanism. The tripping actuator (100) further includes a push rod (7) configured to be ejected out of the tripping actuator (100) by receiving push of the elastic lever mechanism and trigger the tripping mechanism (200). According to the present disclosure, a small motion stroke of the limiting block (2) can trigger a large motion stroke of a lever swinging mechanism, and even if a current flowing through an electromagnetic driving mechanism that drives the limiting block (2) is small and an electromagnetic force is weak, a tripping triggering action with fast speed, high sensitivity and large force can be realized by means of an elastic release process of the elastic lever mechanism.