Shunt Resistor Positioning via Bus Bar Projections

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Solution Overview

Problem

The existing shunt-resistance type current detectors face instability in detection accuracy due to varying positional relations of the shunt resistor with respect to bus bars during welding, leading to inconsistent current measurements, and attempts to stabilize this often increase production costs.

Innovation Solution

A shunt-resistance type current detector design where the shunt resistor is aligned with projected parts on the bus bars before welding, ensuring stable positional relation through welding, using a configuration where the shunt resistor is inserted into a gap between isolated bus bars and connected via weld parts, preventing displacement during the welding process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the shunt resistor is sandwiched between two bus bars during welding, then the welding connection is achieved, but the positional relation becomes unstable and detection accuracy varies

Engineering Contradiction:
Improvedetection accuracyVSAvoidpositional relation stability
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The bus bars are provided with projected parts (protrusions) before the welding process. These projected parts serve as positioning features that guide and constrain the shunt resistor's position during insertion and welding, ensuring consistent positional relationship before the actual welding occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The projected parts on the bus bars act as intermediary positioning elements between the bus bars and the shunt resistor. These intermediaries ensure proper alignment and stable positional relationship during the welding process, preventing direct contact issues and position variations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If trimming processing is applied to stabilize welding state, then detection accuracy is stabilized, but production cost increases

Engineering Contradiction:
Improvedetection accuracy stabilityVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of trimming the shunt resistor after manufacturing, the bus bars are pre-configured with projected parts that provide positioning functionality during assembly and welding. This preliminary action eliminates the need for subsequent trimming operations, stabilizing detection accuracy without adding manufacturing steps.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The positioning function is extracted from the shunt resistor itself (which would require trimming) and transferred to the bus bars through the projected parts. This allows the shunt resistor to maintain its original dimensions while achieving stable positioning through the bus bar features.

Inventive Principle:
Principle #2Taking out (Extraction)

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 method stabilizes the positional relation of the shunt resistor with respect to bus bars during welding, enhancing detection accuracy without increasing production costs, by ensuring consistent current flow and measurement stability.

Implementation Method 1

the shunt resistor is abutted and welded to each of the two bus bars in order to provide a weld part interposed between the shunt resistor and the two bus bars

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP3789773B1Shunt-resistance type current detector
Publication Date: 2022.02.09 YAZAKI CORP
  • EP3789773B1 patent drawingFigure 1
  • EP3789773B1 patent drawingFigure 2
  • EP3789773B1 patent drawingFigure 3A~3B

AI summary

A shunt-resistance type current detector (1) includes a flat-plate shaped shunt resistor (4) joined between a flat-plate shaped first bus bar (2) and a flat-plate shaped second bus bar (3). Each of the bus bars (2, 3) includes respective detection conductors (24, 34) connected to a current detector (6). The shunt resistor (4) and each of the bus bars (2, 3) are joined via weld parts (71, 72). A gap (S1) for mounting the shunt resistor (4) is formed between the first bus bar (2) and the second bus bar (3), and projected parts (23, 33) are formed each being projected toward the gap (S1) from opposing faces (22, 32) opposing to each other in the gap (S1). The shunt resistor (4) comes in contact with each of the projected parts (23, 33) in a top-and-bottom direction.