In-Wheel Motor Speed Sensing with a Lock Nut Magnet Assembly
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Solution Overview
Problem
Conventional vehicle speed sensing apparatuses for in-wheel motor vehicles face design constraints due to installation on hub bearings, leading to increased work processes and interference with other parts, and require separate seals and complex shape sensing mechanisms.
Innovation Solution
An apparatus that measures the rotation speed of a lock nut part driven by the in-wheel motor, incorporating a magnet part and a speed sensor, where the magnet is sintered powder bonded to the lock nut, allowing for varied installation positions and reducing the number of parts needed by eliminating separate magnet components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a speed sensing apparatus is installed on a hub bearing to measure wheel speed, then the vehicle speed can be sensed for ABS and ESC systems, but the number of work processes increases and interference with other parts occurs
Solution Approach 1:
The patent combines the speed sensing function with the lock nut structure by integrating the magnet into the lock nut itself. This merging eliminates the need for separate sensing components installed on hub bearings, thereby reducing the number of work processes while maintaining reliable vehicle speed sensing for ABS and ESC systems
2Reliability
If a separate seal part is added to prevent oil leakage from hub bearing installation, then oil leakage is prevented, but the number of work processes increases
Solution Approach 1:
The patent integrates the sealing function into the lock nut structure itself, eliminating the need for separate seal parts. The lock nut is designed to prevent oil leakage from the hub bearing while maintaining a streamlined assembly process, thereby reducing the number of work processes required
3Measurement precision
If prominences and depressions are formed on a gear to sense wheel speed, then the speed can be measured, but the installation space increases and interference with other parts occurs
Solution Approach 1:
The patent extracts the speed sensing function from the gear structure and relocates it to the lock nut. By using a magnet integrated into the lock nut rather than forming prominences and depressions on the gear, the installation space is reduced and interference with other parts is minimized while maintaining accurate wheel speed measurement
Solution Approach 2:
The patent transitions from a mechanical sensing approach (prominences and depressions on gear surface) to a magnetic sensing approach (magnet in lock nut detected by sensor). This dimensional change from mechanical to magnetic field interaction reduces the physical space required for installation while preserving measurement precision
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 solution increases design flexibility and productivity by simplifying the assembly process and reducing part count, while effectively measuring vehicle speed without interference issues.
Implementation Method 1
a magnet part (50) having a magnetic force
Data Source
AI summary
An apparatus for measuring a speed of a vehicle having an in-wheel motor includes a lock nut part fixed to an outer portion of a rotation shaft rotated by receiving power of the in-wheel motor, and restricting movement of a bearing part positioned outside the rotation shaft; a connection part coupled to the lock nut part; a magnet part having a magnetic force, and fixed to the connection part; and a speed sensor part installed to be separated from the magnet part, and measuring rotations of the magnet part.