Rotation Sensor Ring-Shaped Rib Case Design
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Solution Overview
Problem
The existing rotation sensor technology faces challenges in maintaining measurement accuracy due to fluctuations in the dimension B, which is affected by creep-up of exterior molding resin and deformation of the case during the manufacturing process, leading to increased complexity in inspection steps and potential decline in measurement precision.
Innovation Solution
A rotation sensor design featuring a case with a ring-shaped rib and lead frames that maintain a prescribed insertion depth for the magnetism detection unit, with an exterior molding section that prevents creep-up and deformation, ensuring consistent dimensions and improved rigidity to suppress fluctuations in dimension B.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If exterior molding resin is applied to the case, then the case gains protection and structural integrity, but the resin creeps up on the flange lower flat surface causing dimension C to vary and dimension B to fluctuate
Solution Approach 1:
The patent divides the case into two distinct molding sections: a primary molding section (case body) and a secondary molding section (exterior resin layer). The secondary molding section is designed to terminate below the flange lower flat surface, segmenting the resin application from the critical measurement surface. This segmentation prevents resin creep-up while maintaining protective coverage, thereby resolving the contradiction between case protection and dimension B consistency.
2Ease of manufacture
If the case structure is simplified, then manufacturing becomes easier, but the case deforms during exterior molding causing positioning section distortion and dimension B fluctuation
Solution Approach 1:
The patent applies local reinforcement by adding a ring-shaped rib at the specific location where the secondary molding section contacts the case. This localized structural enhancement strengthens the case at the critical interface without requiring overall case redesign. The ring-shaped rib prevents deformation during exterior molding while maintaining the simplified overall case structure, resolving the contradiction between ease of manufacture and dimension B consistency.
3Measurement precision
If inspection steps are added to manage resin creep-up, then measurement accuracy can be maintained, but manufacturing complexity and costs increase
Solution Approach 1:
The patent implements preliminary action by designing the secondary molding section to automatically terminate below the flange lower flat surface through proper molding die configuration. This design feature proactively prevents resin creep-up before it occurs, eliminating the need for subsequent inspection steps to detect or correct dimension B deviations. The preliminary structural prevention resolves the contradiction between measurement precision and manufacturing complexity.
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 simplifies the manufacturing process, maintains measurement accuracy equivalent to or higher than conventional sensors, and omits the need for inspection steps to manage exterior resin creep-up, while allowing for various pick-up lengths using the same case, thereby reducing costs and complexity.
Implementation Method 1
the magnetism detection unit has magnetism detection means for detecting change in a magnetic field of a magnet provided in the rotary body
Data Source
AI summary
The invention provides a rotation sensor enabling simplification of manufacturing process, such as an inspection step, while maintaining measurement accuracy of the rotation sensor. Lead frames of a rotation sensor have positioning sections which contact a side surface section of a case and, in this state of contact, keep the insertion depth dimension of a magnetism detection unit in the internal space of the case to a prescribed dimension; a flange lower flat surface of a flange section is provided further towards the case bottom surface side than a flange lower flat surface of a ring-shaped rib, a portion of the outer peripheral section of the case and the ring-shaped rib are exposed in a ring shape from an exterior molding section, and the case is provided with a plurality of projections along the inner side surface of the case which constitutes the internal space.