Composite Material Strip for Low-Impedance Current Measuring Resistors
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Solution Overview
Problem
Existing methods for producing low-impedance current measuring resistors fail to effectively connect aluminum and copper components due to the formation of brittle intermetallic phases during thermal welding processes, making them unsuitable for industrial applications, especially in high-current applications like hybrid and electric vehicles where aluminum busbars are used for weight and cost reasons.
Innovation Solution
A composite material band is created using roll cladding or ultrasonic welding to connect aluminum and copper components, allowing for a strong and reliable transition joint, enabling the production of low-impedance current measuring resistors with improved mechanical and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal welding processes (TIG, laser, electron beam welding) are used to join aluminum and copper components, then the components can be connected, but brittle intermetallic phases form making the weld unsuitable for industrial applications
Solution Approach 1:
A copper intermediate layer is introduced between the aluminum and copper components. The aluminum is first welded to the copper intermediate layer (which prevents intermetallic formation), and then the copper intermediate layer is welded to the copper component. This intermediary layer acts as a buffer that eliminates the harmful aluminum-copper intermetallic phase while enabling reliable joint between dissimilar metals.
Solution Approach 2:
The patent replaces thermal welding processes with friction welding for joining the aluminum and copper components. Friction welding is a solid-state joining process that does not involve melting, thereby preventing the formation of brittle intermetallic phases. The mechanical energy from friction heats the interfaces to a plastic state, enabling diffusion bonding without liquid phase formation.
2Reliability
If cold welding processes (friction welding) are used to prevent intermetallic phase formation, then reliable joints are achieved, but the process is labor-intensive and expensive for multi-strip composite material production
Solution Approach 1:
The composite material strip is divided into separate material strips (aluminum strip, copper intermediate layer, copper strip) that are joined individually along their longitudinal edges. This segmentation allows each joint to be optimized independently - using friction welding for the aluminum-copper intermediate layer joint and conventional welding for copper-copper joints - thereby achieving both high reliability and production efficiency.
Solution Approach 2:
The copper intermediate layer is pre-positioned between the aluminum and copper strips before the joining process. This preliminary arrangement enables the aluminum strip to be friction-welded to the copper intermediate layer in a controlled manner, ensuring proper alignment and preventing intermetallic formation from the outset, rather than attempting to control the process during welding.
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 solution enables the production of low-impedance current measuring resistors with high continuous current strength and temperature stability, suitable for industrial applications, particularly in hybrid and electric vehicles, by effectively joining aluminum and copper components without forming brittle intermetallic phases.
Implementation Method 1
A composite material band is created using roll cladding or ultrasonic welding to connect aluminum and copper components
Implementation Method 2
A composite material band is created using roll cladding or ultrasonic welding to connect aluminum and copper components
Data Source
Figure 1A~1C
Figure 1D~1F
Figure 2A~2C
AI summary
The invention relates to a composite material strip for producing an electric component, in particular a resistor, in particular a low-resistance current-measuring resistor, comprising a first material strip (4) made of a copper-containing material, in particular a copper-containing conductor material, for later forming a first connection part of the electric component and comprising a second material strip (3) for later forming a second connection part of the electric component. The first material strip (4) and the second material strip (3) are electrically and mechanically connected together along a longitudinal seam, wherein the second material strip (3) consists of an aluminum-containing material, in particular an aluminum-containing conductor material. The invention further relates to a corresponding production method and to a corresponding component.