Composite Washer With Fuse Bushing for Battery Heat Isolation
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Solution Overview
Problem
Metallic washers used in mechanical connections between energy storage modules and housings in electrical energy stores for motor vehicles exhibit high thermal conductivity, leading to temperature gradients and potential damage to energy storage cells when near heat sources like exhaust-gas systems.
Innovation Solution
A washer composed of a metallic bushing for current path and potential equalization, combined with a thermally insulating material that surrounds the bushing, particularly at the cross-sectional tapering forming a fuse, to reduce thermal conductivity and maintain mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic washer is used for mechanical connection, then good settling behavior, high permissible surface pressure and high robustness are achieved, but high thermal conductivity causes temperature gradients and negative effects on energy storage cells
Solution Approach 1:
The washer is constructed as a composite component with a metallic bushing (for mechanical strength and electrical conductivity) surrounded by thermally insulating material (to reduce heat transfer). This composite structure combines the advantages of both materials while mitigating their individual disadvantages.
Solution Approach 2:
The washer is divided into functionally distinct segments: a metallic bushing for providing mechanical connection and electrical potential equalization, and a surrounding thermally insulating material for heat isolation. Each segment performs its specific function independently.
2Object-affected harmful factors
If a thermally insulating material is used for the washer, then thermal conductivity is reduced, but settling behavior, permissible surface pressure and robustness deteriorate
Solution Approach 1:
The thermally insulating material is combined with a metallic bushing to create a composite washer that achieves both thermal insulation and mechanical robustness. The metallic bushing provides the necessary structural strength while the insulating material surrounds it to reduce heat transfer.
Solution Approach 2:
The metallic bushing is nested within the thermally insulating material, with the insulating material forming an outer shell around the metallic core. This nested structure allows the smaller metallic component to provide mechanical strength while being protected and thermally isolated by the surrounding insulating material.
3Reliability
If a metallic washer is used, then electrical potential equalization is achieved, but electrical conductivity prevents overcurrent protection
Solution Approach 1:
The metallic bushing has a localized reduced cross-sectional area (tapering) that creates a fuse element. This local modification allows the bushing to provide electrical potential equalization under normal conditions while acting as an overcurrent protection device when excessive current flows.
Solution Approach 2:
The metallic bushing is pre-designed with a reduced cross-sectional area that acts as a predetermined weak point. This allows the bushing to safely interrupt overcurrents by melting at the tapered section, protecting the energy storage system from electrical damage.
4Reliability
If the metallic bushing has a reduced cross-sectional area for overcurrent protection, then fuse functionality is achieved, but mechanical strength and thermal insulation at that location are reduced
Solution Approach 1:
The metallic bushing with its reduced cross-sectional area is nested within the thermally insulating material. The insulating material compensates for the reduced mechanical strength at the tapered section by providing external support and maintaining the overall structural integrity of the washer.
Solution Approach 2:
The combination of the metallic bushing and surrounding thermally insulating material creates a composite structure where the insulating material compensates for the localized reduction in mechanical strength of the metallic bushing, maintaining overall washer integrity while enabling fuse functionality.
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 washer provides a robust mechanical connection, reduces heat input to the energy storage module, enables potential equalization, and functions as an overcurrent protection device, effectively addressing the thermal conductivity issues of metallic washers while maintaining operational reliability.
Implementation Method 1
a thermally insulating material, which surrounds the metallic bushing at least in the region of the cross-sectional tapering and which compensates for the cross-sectional tapering, for providing a substantially constant outer diameter of the washer and reducing a thermal conductivity of a heat-conducting path, formed via the washer, between the housing and the energy storage module
Implementation Method 2
a metallic bushing for providing a current path between the contact surfaces for potential equalization between the energy storage module and the housing
Implementation Method 3
The bushing also has, between the end faces, a cross-sectional tapering, which forms a fuse, for interrupting the current path in the event of an overcurrent
Data Source
AI summary
A washer to be arranged in a mechanical connection between an energy storage module and a housing of an electrical energy store for a motor vehicle includes an axial hole for receiving a connector and axially opposing bearing surfaces for pressing against metal contact surfaces of the energy storage module and the housing. The washer has a metal bushing for providing a current path between the contact surfaces for potential equalization between the energy storage module and the housing, the axially opposing faces of the bushing forming the bearing surfaces. The bushing has, between the faces, a tapering cross section forming a fuse for interrupting the current path in the event of overcurrent. A thermally insulating material surrounds the metal bushing at least in the region of the tapering cross section and compensates for the tapering cross section in order to provide a substantially constant outer diameter of the washer and to reduce the thermal conductivity of a heat-conducting path formed by the washer between the housing and the energy storage module.