Angle Sensor Positioning Device Overmolding
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Solution Overview
Problem
Existing angle sensors face challenges in accurately detecting rotation angles with low backlash and high precision while maintaining cost-effectiveness, due to issues with shaft positioning and manufacturing tolerances, leading to significant play and magnetic air gaps.
Innovation Solution
A positioning device is used, divided into first and second device elements, which are molded around the housing to precisely position the shaft and sensor elements, eliminating play and reducing manufacturing costs through efficient assembly and overmolding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the shaft is mounted directly in a bore of the housing, then the manufacturing process is simple, but significant shaft play occurs and bearing surface optimization is complicated
Solution Approach 1:
A positioning device with first and second device elements is introduced as an intermediary component between the shaft and housing. This positioning device precisely determines the radial and axial position of the shaft and first sensor element relative to the second sensor element, eliminating the need for complex direct mounting while maintaining manufacturing simplicity.
2Manufacturing precision
If a metallic bearing bushing is pressed into a housing bore, then shaft play is reduced, but the housing bore and bearing bushing require very tight tolerances leading to high costs
Solution Approach 1:
The positioning device serves as an intermediary that achieves precise shaft positioning without requiring tight tolerances on the housing bore or bearing bushing. The device elements are designed to work together with the overmolding process to eliminate play while maintaining cost-effectiveness.
Solution Approach 2:
The invention changes the approach from mechanical tolerance control to a combination of positioning device geometry and overmolding pressure. The housing is at least partially overmolded around the positioning device, using molding pressure to eliminate air gaps and shaft play, thereby relaxing tolerance requirements.
3Manufacturing precision
If tight tolerances are applied to housing bore and bearing bushing, then shaft play is minimized, but the magnetic air gap in the axial direction increases due to cumulative tolerances
Solution Approach 1:
The invention transitions from tolerance-based positioning to overmolding pressure-based positioning. The housing is at least partially overmolded around the positioning device, and the molding process applies pressure that eliminates air gaps and minimizes shaft play, thereby controlling the magnetic air gap without relying on tight mechanical tolerances.
4Reliability
If the positioning device uses screws or other fasteners to join device elements, then the assembly is secure, but manufacturing complexity and cost increase
Solution Approach 1:
The housing material acts as an intermediary that joins the first and second device elements without requiring screws or fasteners. The housing is at least partially overmolded around the positioning device, and the molding process creates a secure mechanical bond between the device elements and the housing, eliminating the need for additional fastening components.
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 allows for precise and cost-effective detection of rotation angles with minimal backlash, ensuring accurate sensor operation and reduced production costs by eliminating air gaps and optimizing shaft positioning.
Implementation Method 1
the housing is at least partially overmolded around the positioning device, wherein the positioning device is divided into a first and a second device element
Implementation Method 2
The other sensor element, for example a Hall sensor, detects the shaft's rotation by measuring changes in the magnetic field
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to an angle sensor (1) for detecting a rotation angle based on a relative angular position of a physical field, comprising a first and a second sensor element (28, 37) between which the physical field is transmissible, wherein the first sensor element (28) is configured as a transmitter element and the second sensor element (37) as a receiver element or vice versa, a rotatably mounted shaft (20) on which the first sensor element (28) is fixed, a housing (40) comprising a cylindrical section (42) for receiving the shaft (20), wherein the housing (40) is at least partially overmolded around a positioning device (30), wherein the positioning device (30) is divided into a first and a second device element (30a, 30b) and wherein the positioning device (30) determines the radial and axial position of the shaft (20) and the first sensor element (28) relative to the second sensor element (37).