Integrated Fuse with Mechanical Preload for Dual Protection
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Solution Overview
Problem
Existing fuse designs that combine thermal and short-circuit protection are structurally complex, require significant space, and lack a cost-effective means to display both triggering mechanisms simultaneously.
Innovation Solution
A fuse design that integrates both thermal and short-circuit protection functions into a single component, utilizing a fusible wire and solder connection that melts under high currents, with a mechanical preload to prevent arc formation outside the fuse and a display mechanism indicating trigger events, allowing for compact and cost-effective construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate thermal fuse and short-circuit fuse are used, then thermal protection and short-circuit protection are provided, but device complexity and space requirements increase
Solution Approach 1:
The patent combines thermal fuse and short-circuit fuse into a single integrated fuse unit. The fuse element serves dual purposes: it provides short-circuit protection by melting under high current, and thermal protection through a separate thermal element that responds to excessive temperature. This merging eliminates the need for separate fuse components and their associated mounting structures, directly reducing device complexity while maintaining comprehensive protection coverage.
Solution Approach 2:
The fuse element is designed with multi-functionality, serving both as a short-circuit protection device and a thermal protection device. The single fuse unit incorporates both the fusible conductor for short-circuit response and the thermal element for temperature-based protection, allowing one component to perform multiple protective functions that would traditionally require separate devices.
2Reliability
If separate thermal fuse and short-circuit fuse are used, then both protection functions are achieved, but space requirements increase
Solution Approach 1:
By merging the thermal fuse and short-circuit fuse into a single integrated unit, the patent significantly reduces the space occupation. The fuse element with its dual-function design eliminates the need for separate fuse holders, mounting structures, and associated clearance spaces that would be required if two separate fuses were installed, directly addressing the space constraint while maintaining comprehensive protection.
3Reliability
If separate thermal fuse and short-circuit fuse are used, then both protection mechanisms are provided, but manufacturing cost and assembly effort increase
Solution Approach 1:
The integration of thermal and short-circuit protection into a single fuse element simplifies manufacturing processes. Instead of producing, inventorying, and assembling two separate fuse components, the patent enables production of a single multi-functional fuse unit, reducing manufacturing steps, lowering material handling costs, and simplifying quality control procedures while delivering comprehensive protection coverage.
4Speed
If fuse element is made thin for fast response, then tripping speed improves, but mechanical strength decreases
Solution Approach 1:
The fuse element incorporates local quality variations through the ceramic core structure. The thin fusible conductor provides fast tripping response where needed, while the ceramic core provides mechanical strength and structural support throughout the element. This localized differentiation of functions allows the fuse to achieve both fast response characteristics and adequate mechanical strength that would be difficult to obtain with a uniform design.
Solution Approach 2:
The fuse element uses a composite structure combining a thin fusible conductor with a ceramic core. The ceramic material provides mechanical strength and structural integrity, while the thin conductor layer enables rapid thermal response and fast tripping. This composite design allows the fuse element to simultaneously achieve fast tripping speed and sufficient mechanical strength for handling and installation.
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 dual-function fuse provides enhanced protection against both thermal and overcurrent faults, reduces component complexity and size, and ensures safe and fast tripping with minimal power loss, meeting safety and normative requirements while reducing assembly effort and costs.
Implementation Method 1
the fusible wire 3d is dimensioned so that it melts when exposed to a high I 2
Implementation Method 2
the solder connection 3c is designed so that when externally heated by the protective component 2, the solder connection 3c melts above a specified temperature due to the thermal connection via the connection 2a to the cap 3a
Implementation Method 3
The connecting electrode 4 is held in a guide 8 in the cap 3b so as to be movable relative to the body 3f of the fuse 3 and is under a mechanical prestress 6 relative to the body 3f of the fuse 3
Data Source
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AI summary
The subject matter of the invention is a fuse (3) for connection to a protection component (2) of a surge protection device (2), wherein the fuse (3) has a housing (3f), a first cap (3a), a second cap (3b) and a fusible wire (3d), which runs between the first cap (3a) and the second cap (3b) within the housing, wherein the first cap (3a) is designed for thermal and electrical connection to the protective component (2), wherein the fusible wire (3d) is held on the first cap (3a) by means of a soldered joint (3c), wherein the fusible wire (3d) is fastened on a connection electrode (4) with respect to the first cap (3a), wherein the connection electrode (4) is held in a guide (8) movably with respect to the body of the fuse (3) and is under mechanical prestress (6) with respect to the body of the fuse (3), wherein the fusible wire (3d) is designed in such a way that it fuses when a high I2t is applied, and wherein the soldered joint (3c) is designed in such a way that the soldered joint (3c) fuses in the event of external heating by the surge protection device (2) to above a specified temperature owing to the thermal connection, and wherein the electrical contact between the first cap (3a) and the connection electrode (4) is released in the event of fusing of the fusible wire (3d) and the soldered joint (3c) owing to the mechanical prestress (6).