Torque Detection Device Resin Flow Passage Design
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Solution Overview
Problem
The existing torque detection devices in electric power steering systems face issues with deformation of the magnetic shield due to resin pressure during the process of forming the sensor housing, which affects the accuracy of torsion angle calculation.
Innovation Solution
The torque detection device incorporates resin flow passages in the holder to direct resin flow through specific passages, preventing deformation of the magnetic shield and ensuring accurate torsion angle measurement by maintaining the shield's position relative to the magnetic flux collecting rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resin is supplied onto the outer periphery of the magnetic flux collecting unit to form the sensor housing, then the waterproof property is improved, but the magnetic shield deforms due to resin pressure
Solution Approach 1:
The holder is segmented into multiple functional regions: a resin flow passage formation region that directs resin flow, a magnetic shield support region that provides structural support to the magnetic shield, and a magnetic flux collecting ring support region. This segmentation allows the resin flow to be controlled away from the magnetic shield while still achieving waterproofing through the integrated sensor housing.
Solution Approach 2:
The resin flow passage acts as an intermediary channel that guides the resin flow from the injection point to the sensor housing formation area, preventing direct contact between the resin pressure and the magnetic shield. The magnetic shield support region serves as an intermediary structure that bears the resin pressure, protecting the magnetic shield from deformation.
2Measurement precision
If the magnetic shield is positioned to cover the through-holes, then the magnetic flux collection is improved, but the magnetic shield deforms under resin pressure during sensor housing formation
Solution Approach 1:
The holder is pre-formed with a magnetic shield support region and resin flow passage formation region before the sensor housing is formed. This preliminary structural preparation ensures that when resin is supplied, the magnetic shield is already supported at critical positions, preventing deformation before it can occur during the resin curing process.
Solution Approach 2:
The holder provides localized support to the magnetic shield at specific critical positions where the magnetic shield contacts the through-holes. The magnetic shield support region provides enhanced structural strength exactly where needed, while other areas of the holder maintain their original properties for resin flow and magnetic flux collection.
Data Source
AI summary
A torque detection device includes: a magnetic flux collecting unit, and a sensor housing. The magnetic flux collecting unit includes a holder, first and second magnetic flux collecting rings, and a magnetic shield. The holder has upper and lower through-holes. The first and second magnetic flux collecting rings are fitted to an inner periphery of the holder. The magnetic shield is fitted to an outer periphery of the holder so as to cover the through-holes. The sensor housing is formed integrally with the magnetic flux collecting unit by supplying resin onto an outer periphery of the magnetic flux collecting unit. The holder has a resin flow passage in its outer periphery. Resin that is supplied at the time of forming the sensor housing flows into the through-holes through the resin flow passage.