Torque Detection Device Static Electricity Shielding
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Solution Overview
Problem
Existing torque detection devices in electric power steering systems are susceptible to static electricity intrusion, which can cause abnormalities in the magnetic sensor's integrated circuit due to the presence of clearances in the magnetism collection holder that allow external static electricity to flow into the sensor.
Innovation Solution
The torque detection device employs a configuration where positioning recessed portions and protrusions are strategically placed to fill the gaps between the first and second magnetism collection holders, blocking communication between the inside and outside, thereby preventing static electricity from entering the magnetism collection holder and the magnetic sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If clearances are provided in the magnetism collection holder for positioning during molding, then manufacturing precision is improved, but static electricity can flow into the magnetic sensor through the clearance
Solution Approach 1:
A magnetic shield is introduced as an intermediary component between the external environment and the magnetic sensor. The shield is positioned to cover the clearance in the magnetism collection holder, blocking static electricity from reaching the sensor while allowing the clearance to remain for manufacturing purposes. This mediator resolves the contradiction by providing electrical protection without compromising manufacturing precision.
Solution Approach 2:
The magnetic shield is pre-installed on the magnetism collection holder before assembly with other components. This preliminary protective measure ensures that the clearance is already protected against static electricity intrusion before the device is fully assembled and put into operation, preventing harmful effects from occurring.
2Reliability
If a magnetic shield is added to block external magnetic field noise, then reliability is improved, but device complexity increases
Solution Approach 1:
The magnetic shield serves multiple functions simultaneously: it blocks external magnetic field noise from reaching the magnetic sensor, and it also prevents static electricity intrusion through the clearance. By making the shield multi-functional, the invention improves reliability against multiple harmful factors without adding additional protective components, thus avoiding increased device complexity.
Solution Approach 2:
The protective function against static electricity and the protective function against external magnetic field noise are merged into a single magnetic shield component. This consolidation eliminates the need for separate protective measures, maintaining device simplicity while achieving comprehensive protection and improving overall reliability.
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 configuration effectively suppresses the intrusion of static electricity into the magnetism collection holder and the magnetic sensor, preventing abnormalities in the integrated circuit and ensuring reliable operation of the torque detection device.
Implementation Method 1
a plurality of magnetic yokes that are fixed to the output shaft and that form a magnetic circuit that matches the magnetic field of the permanent magnet, a pair of magnetism collection rings that guide magnetic flux from the magnetic yokes
Implementation Method 2
a permanent magnet fixed to the input shaft
Data Source
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AI summary
A torque detection device capable of suppressing intrusion of static electricity into a magnetism collection holder and an electric power steering system that includes the torque detection device are provided. A magnetism collection unit (70) includes magnetism collection rings (71a, 71b), first and second magnetism collection holders (72a, 72b) that hold the magnetism collection rings (71a, 71b), respectively, and a magnetic shield (80) that covers the outer peripheries of the magnetism collection rings (71a, 71b). The inner peripheral surface of the first magnetism collection holder (72a) is provided with recessed portions (78). The outer peripheral surface of the second magnetism collection holder (72b) is provided with engagement protrusions (77) to be inserted into the recessed portions (78). The inner peripheral surface of the second magnetism collection holder (72b) is provided with recessed portions (101). The inner peripheral surface of the first magnetism collection holder (72a) is provided with protrusions (100) that project toward the second magnetism collection holder (72b). The protrusions (100) are inserted into the recessed portions (101) when the first magnetism collection holder (72a) and the second magnetism collection holder (72b) are assembled to each other.