In-wheel Motor Speed Sensor Using Integrated Magnetic Encoder
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Solution Overview
Problem
Conventional speed sensing devices for vehicles with in-wheel motors require additional manufacturing processes and space for sealing and installing protrusions and grooves, leading to potential interference with other components and increased complexity.
Innovation Solution
A magnetic encoder is mounted to a transmission gear rotated by the in-wheel motor, with a measurement target having magnetic force and a speed sensor positioned apart to measure the rotation, eliminating the need for separate sealing and allowing for varied installation configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional speed sensing device is installed on a hub bearing with protrusions and grooves, then speed measurement is achieved, but the number of manufacturing processes increases and sealing requirements are added
Solution Approach 1:
The measurement target is integrated directly into the transmission gear structure, merging the gear function with the speed measurement function. This eliminates the need for separate sealing components and reduces manufacturing processes while maintaining accurate speed measurement capability.
Solution Approach 2:
The transmission gear serves dual purposes: power transmission and speed measurement. By forming the measurement target directly on the gear, the same component performs both mechanical transmission and sensing functions, reducing overall device complexity.
2Measurement precision
If protrusions and grooves are formed on the gear outer circumferential surface, then speed sensing is enabled, but separate space is needed which may interfere with other parts
Solution Approach 1:
The measurement target is merged with the transmission gear body, eliminating the need for separate sensing parts and their installation space. The gear itself becomes the measurement target, freeing up space that would otherwise be occupied by external sensing components.
3Productivity
If a magnetic encoder is mounted to the transmission gear, then design freedom and productivity are enhanced, but additional mounting structure is required
Solution Approach 1:
The measurement target is formed integrally with the transmission gear through casting or molding, eliminating the need for separate mounting structures. This integration enhances productivity by simplifying installation while reducing device complexity by removing additional 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 design enhances design freedom and productivity by integrating the measurement target into the transmission gear, reducing the need for additional sealing components and simplifying the installation process while maintaining accurate speed measurement.
Implementation Method 1
a measurement target having magnetic force and mounted in the mounting groove part
Data Source
AI summary
An apparatus for measuring a speed of a vehicle having an in-wheel motor may include: a transmission gear configured to be rotated by power transmitted from the in-wheel motor, and including a mounting groove formed along a circumferential direction; a measurement target having magnetic force and mounted in the mounting groove; and a speed sensor installed at a position spaced apart from the measurement target and configured to measure rotation of the measurement target part.