Power Tool Toggle Switch Insulating Tube
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Solution Overview
Problem
Existing angle grinder designs suffer from metal filings entering the motor housing via air flow, leading to short circuits between exposed metal plates of the toggle switch, causing unsafe operation and potential fires due to uncontrolled power activation and plastic housing ignition.
Innovation Solution
The integration of an insulating resilient tube surrounding the terminal plates, in addition to an insulating sleeve, ensures complete enclosure of the plates, preventing metal filings from causing short circuits by filling gaps and expanding to cover any exposed parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal plates of the toggle switch are exposed to enable electrical connection, then electrical conductivity is improved, but the risk of short circuit from metal filings increases
Solution Approach 1:
The patent applies local quality by providing different surface treatments to different parts of the terminal plates. The portions that require electrical connection remain exposed and conductive, while other portions are covered with insulating material to prevent short circuits. This localized differentiation allows the same component to have both conductive and insulating properties in different areas, resolving the contradiction between electrical connection reliability and short circuit prevention.
Solution Approach 2:
The terminal plates are segmented into multiple functional zones: exposed conductive portions for electrical connection and insulating-covered portions for short circuit prevention. This segmentation allows each portion to perform its specific function independently, enabling the terminal plate to simultaneously achieve reliable electrical connection while preventing harmful short circuits from metal filings.
2Object-affected harmful factors
If insulating material is added to cover terminal plates, then short circuit prevention is improved, but electrical conductivity deteriorates
Solution Approach 1:
Instead of uniformly covering the terminal plates with insulating material, the patent applies insulation only to specific portions that do not require electrical connection. The terminal plates maintain exposed conductive surfaces where electrical connections are needed, while insulating material covers only the areas where short circuit prevention is required. This localized approach resolves the contradiction by allowing both insulation and conductivity to coexist in the same component.
3Object-affected harmful factors
If resilient insulating tube is added to surround terminal plates, then short circuit prevention is improved, but device complexity increases
Solution Approach 1:
The patent merges the insulating tube with the terminal plate assembly by positioning the resilient insulating tube to surround the terminal plates and engage with the switch body. This integration allows the insulating tube to serve dual purposes: providing short circuit prevention while also acting as a structural component of the switch assembly. The resilient nature of the tube allows it to accommodate manufacturing tolerances and assembly variations, reducing the need for additional adjustment mechanisms.
Solution Approach 2:
The resilient insulating tube acts as an intermediary element between the terminal plates and the external environment (metal filings). It provides a protective barrier that prevents metal filings from causing short circuits while allowing the terminal plates to maintain their electrical connection function. The tube's resilient property allows it to deform slightly to accommodate assembly variations, making the overall design more robust without requiring complex adjustment mechanisms.
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 effectively prevents short circuits and reduces the risk of fire by ensuring that metal filings cannot conduct electricity between the plates, ensuring safe operation and preventing uncontrolled power activation.
Implementation Method 1
a resilient insulating tube mounted on and surrounding the terminal plate, the resilient insulating tube being positioned on the terminal plate between the insulating sleeve and the body of the switch
Data Source
Figure 1
Figure 2
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AI summary
A power tool comprises: a housing (2); an electric motor (14) mounted within the housing; an insulated wire (46, 47) which is electrically connected to the motor and is capable of providing an electric current to the motor; and an electric switch (30) connected in series with the insulated wire, the electric switch comprising a body (32) and at least one electrical terminal plate (34) extending from the body. An exposed end of the insulated wire is electrically connected to the end of the terminal plate. The exposed end of the wire and the end of the terminal plate are enclosed within an insulating sleeve (50). A resilient insulating tube (52) is mounted on and surrounds the terminal plate, the resilient insulating tube being positioned on the terminal plate between the insulating sleeve and the body of the switch to enclose the part of the terminal plate located between the body and the insulating sleeve.