In-Wheel Motor Rim Interference Coupling for Reduced Wheel Complexity
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Solution Overview
Problem
Existing wheel devices with integrated electric motors for sports vehicles are complex and costly due to the high number of components and mechanical connections, necessitating a simplified and cost-effective alternative without compromising performance or reliability.
Innovation Solution
A wheel device with an integrated brushless permanent magnet synchronous motor where the rim is coupled to the rotor via interference, eliminating the need for gearmotors and reducing components by using a radial bearing to support the rotor and rim, allowing direct transmission of rotation and central load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an electric motor is integrated onto the wheel, then transmissions become unnecessary and interior space increases, but the complexity of the wheel increases with more components and mechanical connections
Solution Approach 1:
The patent merges the wheel and motor into a single integrated unit, eliminating the need for separate transmission components. The motor is positioned with its rotor directly coupled to the wheel hub, combining functions that were previously separate (wheel rotation and motor drive) into one unified structure, thereby reducing overall system complexity despite adding motor components.
Solution Approach 2:
The wheel assembly serves multiple functions simultaneously: it acts as both the wheel for vehicle movement and as the housing/mounting structure for the electric motor. The wheel hub serves dual purposes as both the structural center of the wheel and as the motor mounting platform, reducing the need for additional components and simplifying the overall system architecture.
2Ease of manufacture
If the number of components and mechanical connections is reduced, then manufacturing becomes simpler and costs decrease, but reliability and performance may be compromised
Solution Approach 1:
By merging the wheel and motor into a single integrated assembly, the patent reduces the total number of discrete components that need to be manufactured and assembled. This integration simplifies manufacturing processes and reduces assembly steps while maintaining reliability through the direct structural coupling of the motor to the wheel hub, eliminating intermediate connection points that could fail.
Solution Approach 2:
The motor is positioned such that its center of gravity aligns with the wheel hub center, creating a balanced configuration. This equipotential positioning ensures even load distribution across the bearing and structural components, preventing stress concentration and enhancing reliability while simplifying the mounting structure by eliminating the need for additional balancing or support elements.
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 configuration enhances robustness and reliability, minimizes component count for easier manufacturing, and provides accurate force and torque sensing for improved vehicle dynamics while maintaining efficiency and performance.
Implementation Method 1
at least one radial bearing (13) supporting the rotor (12) and therefore the rim (5) on the wheel hub (9) rotatably about the axis H
Implementation Method 2
The rim (5) is coupled to the rotor (12) by interference, such that a rotation of the rotor (12) about the axis H is directly transmitted to the rim (5)
Data Source
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AI summary
A wheel device (4) for a motor vehicle (1) includes a rim (5) having an axis (H) and an outer surface (6) defining a seat (7) for mounting a tire (8), a wheel hub (9) arranged about the axis (H) inside the rim (5) and suitable to be coupled to a suspension of the motor vehicle (1), an electric motor (10) comprising a stator (11) arranged coaxially with the wheel hub (9) in a fixed position with respect to the wheel hub (9) and a rotor (12) configured to magnetically interact with the stator (11), a radial bearing (13) supporting the rotor (12) rotatably about said axis (H) with respect to the wheel (9) and to the stator (11), wherein the rim (5) is fitted on the rotor (12) with interference, whereby the rim (5) is fixed with respect to the rotor (12).