Overcurrent Relay Rocker Snap Spring Mechanism
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Solution Overview
Problem
Existing overload relays exhibit reduced dielectric strength and switching capacity in automatic mode due to a reduced contact gap, limiting their use at higher voltages.
Innovation Solution
The rocker is held in its closed positions by a snap spring, allowing it to snap over a dead center position, with a functional spring supporting or blocking the snapping action based on the mode of operation, maintaining consistent contact gap in both manual and automatic modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the contact gap is reduced to enable snap-action switching for automatic mode, then the automatic reset function is achieved, but the dielectric strength and switching capacity are reduced
Solution Approach 1:
The patent applies a snap spring mechanism that dynamically changes the contact gap spacing. In automatic mode, the snap spring maintains reduced spacing for immediate reset. In manual mode, the snap spring is disengaged and the contact gap is increased to standard spacing, restoring dielectric strength while preventing automatic snapping back.
Solution Approach 2:
The contact gap parameter is changed based on operating mode. The snap spring mechanism physically adjusts the contact gap distance - reduced when engaged (automatic mode) and increased when disengaged (manual mode). This parameter change resolves the contradiction by allowing optimized spacing for each mode.
2Extent of automation
If the contact gap is reduced for snap-action switching, then automatic mode operation is enabled, but the switching capacity is reduced
Solution Approach 1:
The switching capacity is dynamically adjusted through the snap spring mechanism. When the snap spring is engaged for automatic mode, the reduced contact gap limits switching capacity. When disengaged for manual mode, the full contact gap is restored, maximizing switching capacity for manual operations.
3Extent of automation
If the rocker is designed to snap back automatically when overcurrent ceases, then automatic protection is achieved, but the device cannot maintain stable tripped state for manual intervention
Solution Approach 1:
The rocker's snapping behavior is dynamically controlled by the snap spring engagement. When engaged, the rocker snaps back automatically upon overcurrent cessation, providing automatic protection. When disengaged, the rocker remains stable in the tripped position, allowing manual intervention. The snap spring acts as a switchable constraint that enables or prevents automatic resetting.
Solution Approach 2:
The snap spring serves as an intermediary mechanism between the thermal element and the rocker. It mediates the rocker's movement by providing either automatic snapping force or stable positioning force, depending on its engagement state. This intermediary control resolves the contradiction between automatic and manual operation modes.
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 design ensures the overload relay maintains the same switching capacity in both modes, enabling safe operation at higher voltages up to 690 V by preventing immediate snapping back in manual mode and allowing immediate reset in automatic mode.
Implementation Method 1
the rocker is held in its first or second closed position by a snap spring and can snap over a dead center position between the two closed positions against the restoring force of the snap spring
Implementation Method 2
a functional spring interacts with the rocker in such a way that it supports snapping of the rocker from the first to the second closed position, and that the function spring can release or block snapping back of the rocker
Implementation Method 3
Known overcurrent relays have thermobimetals as thermal tripping elements, which are heated by the overcurrents and bend
Data Source
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AI summary
The invention relates to an overcurrent relay, having a rocker (20) which is borne such that it can pivot and on which at least one moving contact piece (11) of a contact point (12) is borne, wherein, in the event of an overcurrent, the rocker changes from a first closed position to a second closed position as a result of the influence of a thermal release, and having a switching device (40), which can be switched between a first and a second position, for manual or automatic resetting of the rocker from the second closed position to the first closed position, wherein a. the rocker is held by a snap-action spring in its first or second closed position and can snap over between the two closed positions, via a dead-centre position, against the resetting force of the snap-action spring, wherein b. a function spring interacts with the rocker such that it assists the rocker in snapping over from the first closed position to the second closed position, and wherein c. the function spring can enable or inhibit the rocker snapping back from the second closed position to the first closed position, under the influence of the switching device.