Current Sensor Circuit Board Warping Control
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Solution Overview
Problem
Current sensors face precision issues due to connector insertion/removal forces causing distortion in the circuit board, affecting the clearance between conductors and magnetic sensors, leading to reduced precision.
Innovation Solution
The current sensor design includes a magnetic sensor enclosed by fixing portions and a connector in an extended area with stoppers, allowing only minimal warp in the plate thickness direction, suppressing distortion and maintaining the positional relationship between the bus bar and magnetic sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the connector is mounted in a direction perpendicular to the surface of the circuit board, then the connector can be connected to devices in various positions, but a force is applied directly in a direction perpendicular to the surface of the circuit board when the connector is inserted or removed, causing distortion in the circuit board
Solution Approach 1:
The circuit board is divided into a fixed area (where the magnetic sensor is mounted) and an extended area (where the connector is mounted). This segmentation isolates the connector insertion/removal forces to the extended area, preventing them from affecting the fixed area and maintaining manufacturing precision in the sensor region.
Solution Approach 2:
Stoppers are introduced as intermediary elements between the connector and the circuit board. These stoppers limit the warp of the extended area to an amount equal to the gap with respect to the stopper, acting as a mechanical constraint that prevents excessive distortion from propagating to the fixed area.
2Manufacturing precision
If the connector is mounted parallel to the surface of the circuit board, then distortion is minimized during insertion and removal, but the connector cannot be positioned to connect with devices in various orientations
Solution Approach 1:
The connector is mounted in a direction perpendicular to the surface of the circuit board, utilizing the vertical dimension. This allows the connector to connect with devices in various orientations while the stoppers and area segmentation control the distortion in the horizontal plane, resolving the contradiction between mounting flexibility and stability.
3Ease of operation
If the circuit board warps due to connector insertion/removal forces, then the clearance between the conductor and magnetic sensor changes, but the magnetic sensor precision is compromised
Solution Approach 1:
By dividing the circuit board into fixed and extended areas, the design ensures that warp occurs only in the extended area during connector operation. The magnetic sensor remains in the fixed area where no warp occurs, maintaining the clearance between the conductor and magnetic sensor and preserving measurement precision.
Solution Approach 2:
Stoppers serve as intermediary constraints that limit the warp of the extended area to a controlled amount equal to the gap with respect to the stopper. This controlled limitation prevents excessive warp that would otherwise change the clearance and affect magnetic sensor precision.
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 ensures the precision of the current sensor remains unaffected by connector insertion/removal, maintaining the sensitivity direction and preventing changes in clearance, thus ensuring stable sensor precision.
Implementation Method 1
a magnetic sensor 5 which measures an induced magnetic field generated by the current under measurement
Implementation Method 2
A magnetic core that concentrates and amplifies a magnetic field generated by the current near a detection portion of the bus bar
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A current sensor 1, which is a current sensor that outputs an output to the outside through a connector and does not affect the precision of the sensor even when a connector is inserted or removed, has a bus bar 2 and a case 10 that houses part of the bus bar 2. The case 10 is composed of a case body 11 in a box shape, the upper surface of which is open, and a lid portion 12 that covers the upper surface of the case body 11. A circuit board 4 is fixed to the case body 11 with caulking portions 13 to 15 at three positions. On the circuit board 4, an area enclosed by the caulking portions 13 to 15 at three positions is a fixed area 4a, and an area extending from the caulking portions 13 and 14 is an extended portion 4b. The lid portion 12 is provided with two lid-side stoppers 19. Inside the case body 11, case-body-side stoppers 25 are provided at three positions. When a connector of another device is connected to or removed from the connector 6, the extended portion 4b is warped. However, the warp is suppressed by the case-body-side stoppers 25 and lid-side stoppers 19.