Shunt Resistor Structure for Accurate Large-Current Welding

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Solution Overview

Problem

Conventional shunt resistors face challenges in accurately measuring large currents due to poor welding joints caused by reducing the width of the resistance element to adjust resistance values, leading to inaccurate current measurements.

Innovation Solution

The shunt resistor design incorporates protruding portions on the resistance element that protrude from the longitudinal side surfaces of the base materials, allowing for stable clamping and high-quality welding, even with reduced element width, ensuring accurate current measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the width of the resistance element is reduced to lower the resistance value, then the resistance value decreases, but the welding joint quality deteriorates

Engineering Contradiction:
Improveresistance valueVSAvoidwelding joint quality
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The invention transitions from adjusting resistance by changing the width (lateral dimension) of the resistance element to adjusting resistance by changing the length (longitudinal dimension) of the resistance element. This dimensional shift allows the width to be maintained at a sufficient level for reliable welding while achieving the desired low resistance value through increased length.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the width of the resistance element is reduced to achieve lower resistance values for large currents, then the resistance value decreases, but the welding process becomes difficult to perform

Engineering Contradiction:
Improveresistance valueVSAvoidwelding processability
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention resolves the manufacturing difficulty by shifting the resistance adjustment from the width dimension to the length dimension. This allows the resistance element to maintain a sufficient width for easy welding operations while achieving the required low resistance value through increased length, thereby improving ease of manufacture.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If the width of the resistance element is reduced to lower resistance values, then the resistance value decreases, but the current measurement accuracy deteriorates

Engineering Contradiction:
Improveresistance valueVSAvoidcurrent measurement accuracy
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The invention maintains current measurement accuracy by preserving the width of the resistance element at a sufficient level while adjusting the length to achieve the desired resistance value. This ensures that the resistance element maintains adequate dimensions for accurate current measurement while still providing the required low resistance for large current applications.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 enables accurate current value measurement even with large currents by ensuring sufficient welding bead width and preventing poor joints, enhancing manufacturing quality and reliability.

Implementation Method 1

when a current flows through the above-described shunt resistor 100, the resistance element 101 generates heat and thereby undergoes a change in the resistance value depending on the heat generation temperature

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

two base materials (11) joined by welding (10e) to the resistance element (10) with the resistance element (10) therebetween

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP3712909B1Shunt resistor and method for manufacturing same
Publication Date: 2025.06.25 SUNCALL CORP
  • EP3712909B1 patent drawingFigure 1(a)~1(b)
  • EP3712909B1 patent drawingFigure 2(a)~2(d)
  • EP3712909B1 patent drawingFigure 3

AI summary

The purpose of the present invention is to provide a method for manufacturing a shunt resistor capable of measuring an accurate current value even if a large current flows therethrough. A resistance element 10 is formed such that, when the resistance element 10 is sandwiched between two base materials 11, a first protruding portion 10a and a second protruding portion 10b that protrude from longitudinal side surfaces (one side surface 11a, the other side surface 11b) in the longitudinal direction of the two base materials 11 are provided, and when the two base materials 11 are joined by welding 10e to the resistance element 10 with the resistance element 10 sandwiched therebetween, the first protruding portion 10a and the second protruding portion 10b of the resistance element 10 and the two base materials 11 are clamped and joined by the welding 10e.