Electromagnetic Switch Contact Insulation With Creepage Protrusions
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Solution Overview
Problem
Electromagnetic switches in vehicles face insulation failures between contacts and coils, risking electric shock due to high voltage transmission to low-voltage devices, necessitating enhanced insulation capabilities.
Innovation Solution
A contact apparatus with a plastic insulating part and spaced protrusions on its outer wall increases creepage distance, enhancing insulation between the moving contact and the coil, and includes a moving contact assembly with a push rod, elastic part, and a driving apparatus to ensure safe operation and reduce the risk of foreign matter intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple insulating structure is used between contact and coil, then device complexity is reduced, but insulation capability deteriorates leading to potential electric shock
Solution Approach 1:
The insulating part is segmented with multiple spaced protrusions that divide the insulating surface into multiple regions. This segmentation increases the creepage distance between high-voltage and low-voltage areas by forcing the electrical path to travel along the contoured surface of the protrusions, thereby enhancing insulation capability without requiring a completely redesigned insulating structure
Solution Approach 2:
The protrusions extend in the axial direction of the push rod, adding a dimensional element to the insulating surface. This transforms a potentially two-dimensional insulating problem into a three-dimensional solution, where the protrusions create additional creepage path length without significantly increasing the overall volume of the insulating part
2Reliability
If protrusions are arranged to maximize creepage distance, then insulation capability is improved, but volume of the insulating part increases
Solution Approach 1:
The protrusions are strategically positioned only on specific regions of the insulating part where they are most effective at increasing creepage distance. The spacing and distribution of protrusions are optimized to provide maximum insulation benefit while minimizing material usage and overall volume increase of the insulating component
3Reliability
If insulation distance is increased, then insulation capability is improved, but the height of the insulating part increases
Solution Approach 1:
Instead of increasing height in the axial direction, the protrusions utilize the radial and circumferential dimensions of the insulating part. This redistributes the creepage distance accumulation across different spatial dimensions, achieving enhanced insulation without proportionally increasing the overall height of the insulating component
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 solution effectively improves insulation capabilities, preventing surge voltage transmission and reducing the risk of electric shock, while also minimizing the volume of the electromagnetic switch.
Implementation Method 1
the plastic insulating part is configured to implement insulated isolation between the moving contact and the push rod, to prevent a surge voltage after the moving contact contacts the pair of fixed contacts from being transmitted to a coil
Implementation Method 2
Because a plurality of spaced protrusion structures similar to high-voltage electrical insulators is disposed on the outer wall of the insulating part, a creepage distance on a material surface is increased, and an insulation capability of the insulating part is improved
Implementation Method 3
An operating principle of the electromagnetic switch is that a current flows through a coil to generate a magnetic field, so that a contact is connected or disconnected, to control a load
Data Source
AI summary
An electromagnetic switch, including a driving apparatus and a contact apparatus. The contact apparatus includes a moving contact assembly, a chamber, and two spaced fixed contacts disposed on a top part of the chamber. The moving contact assembly includes an insulating part, a push rod, a moving contact, and an elastic part. One end of the push rod is mounted on the driving apparatus, and the other end of the push rod is mounted on the insulating part. The moving contact is mounted on one side that is of the insulating part and that is back to the push rod. The elastic part is clamped between the insulating part and the moving contact, so that the moving contact is in contact with or separated from the pair of fixed contacts under the action of the push rod.