Injection-Molded Magnetic Sensor Rotor for Precise Shaft Positioning
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Solution Overview
Problem
Existing brake systems with ESP and ABS functionality require precise positioning of permanent magnets for rotor position indication, which involves complex assembly steps and multiple components, leading to increased manufacturing and assembly costs and reduced positioning accuracy.
Innovation Solution
The solution involves direct injection molding of plastic-bonded permanent magnetic material onto the body, eliminating the need for a separate cup and adhesive, and allowing for a more precise and cost-effective integration of the permanent magnet with the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a permanent magnet is fixed to the motor shaft using a cup and adhesive, then the permanent magnet can be positioned on the motor shaft, but the assembly process becomes complex with multiple steps and components
Solution Approach 1:
The cup, adhesive layer, and permanent magnet are merged into a single integrated component. The receiving cup is formed directly as part of the permanent magnet component through injection molding, eliminating the need for separate cup and adhesive applications, thus reducing assembly steps while maintaining positioning accuracy
Solution Approach 2:
The permanent magnet component serves multiple functions simultaneously: it provides magnetic field generation, structural support, and precise positioning features. The integrated design combines the functions of the cup (receiving and positioning), adhesive (bonding), and permanent magnet (magnetic field generation) into one multi-functional component
2Reliability
If a permanent magnet is fixed to the motor shaft using a cup and adhesive, then the permanent magnet can be secured to the shaft, but the number of manufacturing and assembly steps increases
Solution Approach 1:
The receiving cup and permanent magnet are combined into a single injection-molded component, eliminating the need for separate assembly steps of fitting the cup onto the shaft and then bonding the permanent magnet to the cup. This single-component approach maintains secure fixation while significantly improving assembly efficiency
Solution Approach 2:
The receiving cup structure is pre-formed as an integral part of the permanent magnet component during the injection molding process itself, rather than being assembled separately. This preliminary formation of the receiving structure eliminates subsequent assembly steps while ensuring proper fit and secure fixation
3Reliability
If a cup base and adhesive gap are used between the permanent magnet and motor shaft, then the permanent magnet can be isolated magnetically, but the axial tolerance chain becomes longer
Solution Approach 1:
The cup base and adhesive gap, which provided magnetic insulation but introduced tolerance accumulation, are completely removed from the design. Magnetic insulation is achieved through alternative means (such as the magnetic properties of the plastic-bonded permanent magnet material itself or the geometry of the integrated component) rather than through separate insulating layers, thus eliminating the axial tolerance chain while maintaining magnetic insulation
Solution Approach 2:
The plastic-bonded permanent magnet material provides both structural and magnetic properties in a single composite material system. This composite material allows the permanent magnet to be directly mounted on the shaft without requiring separate magnetic insulation layers, reducing the axial tolerance chain while maintaining adequate magnetic field management
4Reliability
If multiple separate components (cup, adhesive, permanent magnet) are assembled, then the permanent magnet can be fixed to the shaft, but the radial tolerance chain increases and positioning accuracy decreases
Solution Approach 1:
The receiving cup, permanent magnet, and positioning features are merged into a single injection-molded component. This integration eliminates the radial tolerance accumulation that occurs when assembling multiple separate components (cup to shaft, then permanent magnet to cup), while maintaining secure fixation through the integrated design
5Reliability
If a separate cup and adhesive are used to fix the permanent magnet, then the permanent magnet can be secured to the shaft, but manufacturing costs increase
Solution Approach 1:
The receiving cup and permanent magnet are combined into a single injection-molded component, eliminating the need for separate cups and adhesive materials. This consolidation reduces the number of bill of materials items and simplifies the manufacturing process, thereby reducing overall manufacturing costs while maintaining secure fixation
Solution Approach 2:
The injection molding process itself creates the integrated permanent magnet component with built-in receiving cup features, eliminating the need for separate fastening or bonding operations. The component is self-contained and self-securing through its integrated design, reducing the need for additional materials and processes
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 approach significantly reduces manufacturing and assembly steps, improves positioning accuracy, and allows for the use of more cost-effective magnetic materials, while ensuring a secure and inseparable connection between the permanent magnet and the body.
Implementation Method 1
a plastic bonded permanent magnetic material is injection molded onto the body as an extension and forms a free end of the body as a permanent magnet
Implementation Method 2
a sensor for a magnetic measuring device for detecting a rotational or translational movement of a body, with a permanent magnet which is connected in a rotationally fixed manner to the body
Data Source
AI summary
A sensor for a magnetic measuring device for detecting a rotational or translational movement of a body includes a permanent magnet which is connected to the body for conjoint rotation and which moves with the body. The sensor is fastened to a body by a method, and the sensor can be used in a magnetic measuring device for contactlessly detecting a rotational movement of a body. Plastic-bonded permanent magnet material is injection-molded onto the body, acting as an extension thereof, and forms a free end of the body acting as a permanent magnet.