Planetary Universal Drive for Wheel Motion Without CV Joints
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Solution Overview
Problem
In-wheel motor driving devices face issues with durability, ride quality due to increased unsprung mass, and are limited by the need for constant velocity joints, which restrict their widespread adoption and spatial utilization in vehicles.
Innovation Solution
A universal driving device featuring a sun gear, ring gear, and a gear train with varying link connection angles and pinions that allow continuous power transmission without constant velocity joints, reducing unsprung mass and improving durability and ride quality by decoupling the motor from the wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an in-wheel motor is directly installed in a driving wheel, then the motor can be integrated with the wheel structure, but the unsprung mass increases causing poor ride quality
Solution Approach 1:
The driving device is segmented into a motor assembly (sun gear) and a wheel assembly (ring gear), connected through a planetary gear train. This separation allows the motor to be positioned in the vehicle body rather than directly in the wheel, reducing unsprung mass while maintaining integration benefits.
Solution Approach 2:
A planetary gear train acts as an intermediary mechanism between the motor and the wheel. The gear train transmits power while accommodating relative motion, enabling the motor to be decoupled from direct wheel attachment and thereby reducing unsprung mass.
2Reliability
If a constant velocity joint is used to transmit power to a moving wheel, then continuous power transmission is achieved, but the space between the power source and the wheel increases
Solution Approach 1:
The planetary gear train is designed with movable links that dynamically adjust their configuration as the wheel moves vertically. This dynamic adaptation maintains continuous gear engagement and power transmission without requiring excessive space, unlike rigid constant velocity joint arrangements.
Solution Approach 2:
The planetary gear train serves multiple functions: it transmits power continuously, accommodates vertical wheel motion, and provides gear reduction. This multi-functionality eliminates the need for separate constant velocity joints, reducing the overall space between power source and wheel.
3Adaptability or versatility
If the motor is positioned close to the wheel for better spatial utilization, then space is optimized, but the motor is exposed to severe impact and vibration reducing durability
Solution Approach 1:
The system is divided into a motor assembly positioned in the vehicle body and a wheel assembly containing the ring gear. This segmentation protects the motor from road impacts and vibrations while maintaining compact spatial arrangement through the planetary gear connection.
Solution Approach 2:
The planetary gear train serves as a protective intermediary, isolating the motor from direct exposure to wheel vibrations and road impacts. The gear train transmits power while mechanically decoupling the motor from the harsh wheel environment, improving durability without sacrificing spatial efficiency.
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 universal driving device enhances slope climbing and acceleration performance, improves motor durability, and optimizes spatial utilization between wheels by maintaining continuous power transmission and reducing the space between the power source and the wheel, while absorbing relative displacements and maintaining phase alignment.
Implementation Method 1
a gear train engaging the sun gear to the ring gear and configured to allow a relative motion between the rotation shaft of the sun gear and the rotation shaft of the ring gear
Data Source
AI summary
A universal driving device includes a sun gear rotatably provided; a ring gear disposed on a rotation plane coplanar to a rotation plane of the sun gear and provided so that a rotation shaft of the ring gear is movable relative to a rotation shaft of the sun gear; and a gear train engaging the sun gear to the ring gear and configured to allow a relative motion between the rotation shaft of the sun gear and the rotation shaft of the ring gear and define a continuous power transmission state between the sun gear and the ring gear.