Dual Wave Profile Sensor Arrangement for Compact Position Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rotational speed and position sensors for electric motor shafts in vehicle drive systems face challenges in accuracy and cost, particularly in applications where axial space is limited, and are prone to contamination by iron particles.
Innovation Solution
A rotational position sensor arrangement using a target disc with dual wave profiles and multiple sensors positioned at different radial distances, which provides out-of-phase signals to determine precise rotational position, speed, and direction, reducing axial length requirements and susceptibility to contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a magnetic ring target is used, then cost is reduced, but iron particles are attracted and contaminate bearings
Solution Approach 1:
The patent extracts the harmful magnetic field interaction by removing the magnetic ring target and replacing it with a non-magnetic metallic target disc. This eliminates the attraction of iron particles while maintaining the sensor functionality through alternative measurement methods using capacitive or inductive sensors.
Solution Approach 2:
The patent uses a simple metallic target disc instead of a complex magnetic ring, achieving cost reduction through simpler materials and manufacturing while avoiding the contamination issue entirely by not using magnetic materials that attract iron particles.
2Length of stationary object
If a single target disc with wave profile is used, then axial space is reduced, but measurement accuracy is limited
Solution Approach 1:
The patent divides the measurement function into multiple independent wave profiles on the same target disc, each profile providing measurement data at different radial positions. This segmentation allows the system to achieve high accuracy through signal combination while maintaining compact axial dimensions.
Solution Approach 2:
The patent transitions from a single radial measurement dimension to multiple radial dimensions by placing wave profiles at different radial distances from the axis. This multi-dimensional approach enables accurate rotational position determination within a compact axial footprint by combining signals from multiple radial positions.
3Measurement precision
If multiple wave profiles at different radial distances are used, then accuracy is improved, but device complexity increases
Solution Approach 1:
The patent makes the single target disc universal by incorporating multiple wave profiles that serve different measurement functions simultaneously. Each wave profile contributes to the overall accuracy, and the same physical component performs multiple measurement tasks, reducing the need for separate sensors or targets.
Solution Approach 2:
The patent merges multiple measurement functions into a single integrated target disc with multiple wave profiles. By combining the measurement capabilities of multiple radial positions into one component, the system achieves high accuracy without proportionally increasing device complexity, as all profiles are processed together in a unified sensor arrangement.
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
The solution enhances accuracy and precision while reducing manufacturing costs and axial packaging needs, providing a robust and cost-effective sensor solution for electric motor applications.
Implementation Method 1
The first and second sensors can be inductive sensors, Hall effect sensors, TMR (Tunnel Magneto Resistance) sensors, or any other suitable sensor that detects a change in a magnetic field based on a metallic target being in the field.
Implementation Method 2
The first and second sensors can be inductive sensors, Hall effect sensors, TMR (Tunnel Magneto Resistance) sensors
Data Source
AI summary
A rotational position sensor arrangement having first and second sensors positioned adjacent to an axial face of a target disc. The target disc has the axial face either one wave profile or radially spaced apart first and second wave profiles, having respectively, a first plurality of segments and a second plurality of segments, with each of the segments being formed with axially offset peaks and valleys which extend along radial lines. The valleys separate the segments, and the number of the first plurality of segments is different than the number of the second plurality of segments. The first and second sensors are located at different radial distances from the axis and signal a controller with data on a field variance due to a difference in at least one of a size or location of the one wave profile or the first and second wave profiles as they pass the first and second sensors in order to determine a rotational speed and/or position.