Staggered Multi-Contact Contactor for Arc-Limited Switching
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Solution Overview
Problem
Existing contactors in motor vehicle on-board electrical networks face issues such as arcing and the tendency for contact fusion during switching, which can lead to destruction due to overcurrent-induced levitation.
Innovation Solution
A contactor design with staggered contact elements having different transmission resistances, where a second contact element with higher resistance limits current during switching, preventing arcing and fusion by commutating current through a lower resistance element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex measures such as arc quenching chambers or vacuum chambers are implemented, then arcing and contact fusion are reduced, but device complexity increases
Solution Approach 1:
The moveable contact unit is segmented into at least two separate contact elements: a first contact element for normal current conduction and a second contact element for current limitation during switching. This segmentation allows each contact element to have specialized functions, reducing arcing and contact fusion without requiring complex external protective structures.
Solution Approach 2:
Different contact elements are assigned different transmission resistances tailored to their specific functions. The second contact element has higher transmission resistance specifically for current limitation during switching, while the first contact element has lower transmission resistance for efficient normal operation. This local differentiation of properties enables reliable switching without complex protective measures.
2Device complexity
If a single contact element is used for both normal conduction and switching, then device complexity is reduced, but arcing and contact fusion occur during switching
Solution Approach 1:
The single contact element is divided into multiple contact elements with distinct functions. The first contact element handles normal current conduction, while the second contact element specifically handles switching operations with current limitation. This segmentation eliminates arcing and contact fusion by ensuring that switching always occurs through the current-limiting second contact element.
Solution Approach 2:
The second contact element acts as an intermediary during the switching process. It temporarily conducts and limits the current during the transition period between open and closed states, protecting the first contact element from arcing and fusion. This intermediary mechanism enables reliable switching without the harmful effects that would occur with a single contact element.
3Speed
If current is not limited during switching, then switching speed is improved, but overcurrent-induced levitation and contactor destruction occur
Solution Approach 1:
The second contact element is designed to automatically engage and limit current during the switching process before the first contact element fully closes. This preliminary current limitation prevents overcurrent-induced levitation and contactor destruction, while still allowing rapid switching operation. The staggered closing sequence ensures protection is in place before full current flow begins.
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 design effectively reduces arcing and prevents contactor destruction by managing current transitions, ensuring reliable operation and longevity.
Implementation Method 1
a second electric contact formed between the stationary contact unit and the at least one second contact element assumes a higher second transmission resistance
Data Source
AI summary
A contactor for wiring components of an onboard electrical system, includes: a stationary contact unit for electrically connecting to the onboard electrical system components; a movable contact unit, and an actuation unit for switching the contactor by switching the movable contact unit between a closed state and an open state. The movable contact unit has at least one first contact element for conducting a current and at least one second contact element for conducting and limiting the current during the switching process. A first electric contact formed between the stationary contact unit and the at least one first contact element has a lower transmission resistance than a second electric contact formed between the stationary contact unit and the at least one second contact element. The actuation unit is designed to switch the contact elements between the closed state and the open state in a staggered manner relative to one another so that temporarily only the at least one second contact element contacts the stationary contact unit in order to limit the current during the switching process.