Stacked U-Core Current Sensor with Spacing Supports
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Solution Overview
Problem
Current sensors for hybrid and electric vehicles face issues with hysteresis characteristic deterioration due to compressive strain, affecting accurate current detection.
Innovation Solution
A current sensor design featuring a core formed by stacked U-shaped flat plates with spacing direction supporting portions to reduce compressive strain, maintaining detection accuracy by minimizing core contact with the housing and stabilizing the magnetic field detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the core is fixed to the case by insert molding, then the manufacturing process is simplified and the core is securely fixed, but compressive strain is applied to the core causing hysteresis increase and deterioration of detection accuracy
Solution Approach 1:
The core is divided into multiple stacked flat plates instead of being a single solid piece. This segmentation allows the core to be assembled without insert molding, eliminating compressive strain from the manufacturing process while maintaining secure fixation through the stacked structure and supporting portions.
Solution Approach 2:
Spacing direction supporting portions are introduced as intermediary elements between the core and the case. These supporting portions contact only at specific locations to provide mechanical support without applying compressive strain to the core, thereby mediating between the need for secure fixation and the need to preserve core characteristics.
2Stability of the object's composition
If the core is tightly fixed in the housing, then the core position is stable, but compressive strain increases causing hysteresis deterioration
Solution Approach 1:
The housing structure provides different types of support at different locations: spacing direction supporting portions provide localized support to maintain core position stability, while avoiding widespread contact that would cause compressive strain. This local differentiation of support quality resolves the contradiction between stability and reliability.
Solution Approach 2:
The core is designed with degrees of freedom in the stacking direction, allowing it to adjust its position dynamically within the housing. The supporting portions constrain the core in the spacing direction while permitting movement in the stacking direction, enabling the core to maintain stable positioning without rigid fixation that would cause hysteresis.
3Strength
If multiple parts of the core contact the housing, then the core is well-supported, but compressive strain is distributed throughout the core increasing hysteresis
Solution Approach 1:
The problematic widespread contact between the core and housing is extracted and replaced by a minimal set of discrete supporting portions. Only the necessary supporting portions are retained to provide adequate support strength, while eliminating the harmful distributed contact that causes compressive strain and hysteresis.
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 design effectively reduces hysteresis increase, maintaining the hysteresis characteristic and ensuring accurate current measurement in hybrid and electric vehicles.
Implementation Method 1
a detection element which is arranged on the side of an opening of the U-groove in such a way that a detecting direction extends in a spacing direction of the opening, and which detects a strength of a magnetic field
Implementation Method 2
according to a current flowing through a busbar that connects a DC brushless motor to an inverter, a magnetic field generated around the busbar is magnetically concentrated by a core made of a magnetic body
Data Source
AI summary
A current sensor (100) includes: a core (10) formed by U-shaped flat plates (11, 12) made of a magnetic body and stacked together; a flat plate-like conductor (20) which is inserted on an interior side of a U-groove of the core and through which a current to be measured flows; a detection element (30) which is arranged on the side of an opening of the U-groove in such a way that a detecting direction extends in a spacing direction of the opening, and which detects a strength of a magnetic field; a housing (40) which supports the core, the conductor and the detection element; and a pair of spacing direction supporting portions (15) which are provided at positions along the spacing direction on both sides of the detection element, in an opening-side end of the core, and which abut on the housing.