Rotation Detector Sensor Chip Magnet Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional rotation detectors face accuracy issues due to dimensional deviations between the sensor chip and the biasing magnet, affecting the detection precision of rotating objects like internal combustion engine components.
Innovation Solution
A rotation detector design featuring a holder with an extending portion for accurate positioning of a sensor unit and a cylindrical magnet, protected by a cup-shaped cap member, with a projected portion on the holder engaging a depressed portion on the magnet to ensure precise alignment and reduce positional deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensor chip and magnet are assembled separately and molded together into a unitary housing, then the manufacturing process is simplified and components can be separately prepared, but dimensional deviations occur between components leading to poor positioning accuracy of the sensor chip relative to the magnet
Solution Approach 1:
The patent introduces a positioning protrusion on the sensor chip that engages with a positioning recess in the magnet, serving as an intermediary mechanical feature that ensures accurate relative positioning between the two components during assembly, thereby resolving the positioning accuracy issue while maintaining separate preparation of components
2Reliability
If the sensor chip is molded with resin and assembled with the magnet, then the sensor chip is protected and integrated with circuit, but gaps and positional deviations occur affecting detection accuracy
Solution Approach 1:
The patent incorporates positioning protrusions and recesses as preliminary positioning features before final assembly, ensuring that the sensor chip and magnet are correctly aligned relative to each other before being molded together with resin, thereby preventing gaps and positional deviations that would affect detection accuracy
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 significantly improves the accuracy of rotation detection by ensuring correct positioning of the sensor chip relative to the magnet, enhancing the detection precision and reducing deviations, thus improving the overall performance of the rotation detector.
Implementation Method 1
A sensor chip 101 composed of a pair 1 of magnetoresistive elements (MRE 1 and MRE 2) and another pair 2 (MRE 3 and MRE 4) is positioned to face the rotor RT made of a magnetic material
Implementation Method 2
A magnet 30 for supplying a biasing magnetic field to the sensor chip 101 is disposed around the sensor chip 101
Data Source
AI summary
A rotation detector is positioned to face a rotating object such as a crankshaft of an internal combustion engine. The rotation detector includes a sensor chip mounted on a portion extending from a holder and a magnet for supplying a biasing magnetic field to the sensor chip. Rotation of the rotating object is detected by sensing changes in the magnetic field in which the sensor chip is positioned. A projection is formed on an end surface of the holder while a depression is formed on an end surface of the magnet, and the projection and the depression are tightly engaged with each other to thereby correctly position the magnet relative to the holder. In this manner, the sensor chip is correctly and accurately positioned relative to the biasing magnet. Thus, deviations in rotation detection are minimized, and detection accuracy of the detector is improved.