High-Voltage Fuse Oil-Tightness via Form-Fit Caps
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Solution Overview
Problem
Existing high-voltage fuses are not suitable for use at high temperatures under oil due to insufficient tightness, as material expansion leads to gaps and oil leakage, and the pressure fit between caps and the insulating body loses strength, causing oil-tightness issues.
Innovation Solution
A high-voltage fuse design featuring a form-fit connection between the auxiliary cap, top cap, and insulating body with a single recess serving both form-locking and sealing purposes, utilizing deformation areas and sealing means to ensure a strong, oil-tight connection even at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a press fit connection is used between caps and insulating body, then the structure is simple and production is easy, but the connection strength decreases at high temperatures due to material expansion
Solution Approach 1:
The connection structure is divided into two distinct types: form-fit connection for mechanical interlocking and frictional connection for sealing. This segmentation allows each connection type to perform its specific function optimally - the form-fit connection maintains structural strength at high temperatures while the frictional connection ensures sealing, resolving the contradiction between simple manufacturing and maintaining connection strength.
Solution Approach 2:
The connection system combines two different connection mechanisms (form-fit and frictional) working together. The form-fit connection provides structural integrity through geometric interlocking, while the frictional connection provides sealing through contact pressure. This composite connection approach maintains both strength and sealing capability at elevated temperatures without complicating the manufacturing process.
2Ease of manufacture
If a press fit connection is used between caps and insulating body, then production is cost-effective, but oil-tightness is insufficient at high temperatures due to gap formation
Solution Approach 1:
The sealing function is separated from the mechanical connection function. The form-fit connection handles structural attachment while the frictional connection specifically addresses sealing. This segmentation ensures that oil-tightness is not compromised by thermal expansion, as the frictional connection maintains sealing pressure independently of the form-fit connection's mechanical interlocking.
Solution Approach 2:
The design utilizes the thermal expansion of cap materials at high temperatures to increase contact pressure in the frictional connection, thereby enhancing sealing force. As temperature rises, the caps expand and press more firmly against the insulating body, improving oil-tightness without requiring additional sealing components or complex manufacturing processes.
3Stability of the object's composition
If the insulating body is made closed at high temperatures, then structural integrity is maintained, but internal pressure increases causing caps to lift off
Solution Approach 1:
The connection system separates the mechanical retention function (form-fit connection) from the sealing function (frictional connection). The form-fit connection is specifically designed to resist cap lifting forces through geometric interlocking, while the frictional connection maintains sealing. This segmentation allows the structure to remain closed and structurally intact at high temperatures without caps lifting off due to internal pressure.
4Temperature
If material expansion is allowed at high temperatures, then thermal stress is reduced, but gaps form between components allowing oil penetration
Solution Approach 1:
The design exploits thermal expansion as a beneficial parameter change. As temperature increases to 150°C or higher, the cap materials expand and increase contact pressure in the frictional connection, thereby enhancing sealing force and preventing oil penetration. The form-fit connection accommodates this expansion while maintaining mechanical interlocking, allowing the system to operate at high temperatures without oil leakage.
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 provides adequate oil-tightness and structural integrity at temperatures up to 150°C, preventing oil penetration and cap lifting, while allowing for simple and cost-effective production.
Implementation Method 1
The auxiliary cap and/or the top cap are deformed in such a way that a positive connection between the auxiliary cap and the insulating body and/or between the top cap and the insulating body is established
Implementation Method 2
The auxiliary cap and/or the top cap acts on the sealant in order to produce a high sealing effect
Implementation Method 3
the material expansion of the caps increases with increasing operating temperature. The interference fit between the top cap and the auxiliary cap or between the auxiliary cap and the ceramic insulating body is particularly affected
Data Source
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AI summary
The invention relates to a high-voltage fuse comprising a tubular ceramic insulating member (2) that is provided with at least one fusible element, an inner auxiliary cap (3) which is placed on the insulating member (2) and at least partly covers the outer surface of the insulating member (2) in the front area of the insulating member (2), and an outer top cap (4) that is placed on the auxiliary cap (3) and at least partly covers the outer surface of the auxiliary cap (3). The insulating member (2) is provided with at least one depression. The auxiliary cap (3) is molded against the insulating member (2) such that a positive connection to the insulating member (2) is created in the depression. The auxiliary cap (3) and the top cap (4) are molded in the area of said depression in such a way that a positive connection is created. In order to create a high-voltage fuse which ensures that the insulating member is covered so as to be tight towards the outside even at elevated temperatures, a sealing means (5) is provided in the depression while the top cap (4) and/or the auxiliary cap (3) are molded against the sealing means (5) in said depression.