Rotary Drive With Linear Actuators Reducing Unsprung Mass
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Solution Overview
Problem
Hub motors for vehicles are not effectively suspended by the vehicle's suspension components, contributing to un-sprung mass and affecting ride and handling, as the primary motor mass is not supported by the suspension system.
Innovation Solution
A rotary device with a magnetic stator assembly, opposed electromagnetic actuators, and a linear-to-rotary converter, where the coils reciprocate relative to the magnetic stator assembly to drive the linear-to-rotary converter in rotary motion, allowing the motor components to be supported within the sprung mass, thereby improving suspension and handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hub motor is installed in the wheel, then the motor can drive the wheel directly, but the motor mass becomes un-sprung mass which worsens ride quality and handling
Solution Approach 1:
The motor is divided into two separate assemblies: a stationary magnetic stator assembly mounted to the vehicle chassis, and a moving coil assembly integrated with the wheel. This segmentation allows the heavy stator to remain as sprung mass while the lighter coil assembly rotates with the wheel, reducing un-sprung mass compared to a traditional hub motor while maintaining direct wheel drive capability.
Solution Approach 2:
A linear-to-rotary converter mechanism serves as an intermediary between the linear reciprocating motion of the coil assembly and the rotary motion required to drive the wheel. This converter enables the separated motor components to work together effectively, transmitting power from the stationary stator to the rotating wheel through the reciprocating coil assembly.
2Reliability
If the motor mass is supported by the suspension system, then ride quality improves, but the motor configuration becomes more complex
Solution Approach 1:
The magnetic stator assembly serves multiple functions: it provides the stationary magnetic field for motor operation, acts as a mounting structure for suspension components, and functions as part of the sprung mass supported by the vehicle suspension system. This multi-functionality reduces overall system complexity while improving ride quality.
Solution Approach 2:
The motor components are merged with existing vehicle structures: the magnetic stator assembly is integrated with the vehicle chassis, and the coil assembly is integrated with the wheel assembly. This merging eliminates the need for separate motor mounting structures and simplifies the overall configuration while ensuring proper mass distribution.
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 reduces the un-sprung mass by supporting the motor components within the vehicle's sprung mass, enhancing ride quality and handling by distributing the motor's weight more effectively, and allows for regenerative braking and active suspension capabilities.
Implementation Method 1
opposed electromagnetic actuators, where the coils reciprocate relative to the magnetic stator assembly to drive the linear-to-rotary converter
Data Source
AI summary
A rotary and linear motion device includes a magnetic stator assembly, opposed electromagnetic actuators, and a linear-to-rotary converter (e.g., cam). Each electromagnetic actuator includes a coil that is configured to reciprocate relative to the magnetic stator assembly or to linearly translate in a common direction relative to the magnetic stator assembly. The electromagnetic actuators are coupled to the linear-to-rotary converter and upon reciprocation or linear translation, drive the linear-to-rotary converter in rotary or linear motion. The device may be located inside a wheel, which may be part of a vehicle. If part of a wheel of a vehicle, the device can be used to provide propulsion, steering, braking, and suspension for the vehicle.