In-Wheel Motor Drive Integrating Arm with Speed Reducer Casing
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Solution Overview
Problem
Attaching and fixing in-wheel motor drive units to a knuckle requires thick attachment portions and numerous bolts, leading to increased weight and unsprung weight of the suspension device, affecting ride comfort.
Innovation Solution
An in-wheel motor drive unit with a motor portion, wheel hub portion, and speed reduction portion, where a first arm portion is formed integrally with the speed reduction portion casing, projecting perpendicular to the axis and pivotally coupled to a vehicle body-side member via a ball joint, eliminating the need for bolts and reducing unsprung weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the in-wheel motor drive unit is attached and fixed to a knuckle using conventional methods, then the attachment strength is ensured, but the overall weight and unsprung weight increase due to thick attachment portions and numerous bolts
Solution Approach 1:
The first arm portion is formed integrally with the speed reduction portion casing, merging two separate components into one. This eliminates the need for separate attachment brackets and reduces the number of fastening bolts, thereby reducing unsprung weight while maintaining structural strength through the integrated design
Solution Approach 2:
The speed reduction portion casing serves dual functions: it houses the speed reduction mechanism and simultaneously acts as a mounting structure for the first arm portion. This multi-functionality eliminates the need for dedicated attachment brackets, reducing overall weight while ensuring adequate attachment strength
2Strength
If the in-wheel motor drive unit is attached and fixed to a knuckle using conventional methods, then the attachment strength is ensured, but the number of parts increases due to numerous bolts and nuts
Solution Approach 1:
The first arm portion is formed integrally with the speed reduction portion casing, merging two separate components into one. This eliminates the need for separate attachment brackets and reduces the number of fastening bolts, thereby reducing unsprung weight while maintaining structural strength through the integrated design
Solution Approach 2:
The speed reduction portion casing serves dual functions: it houses the speed reduction mechanism and simultaneously acts as a mounting structure for the first arm portion. This multi-functionality eliminates the need for dedicated attachment brackets, reducing overall weight while ensuring adequate attachment strength
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 unsprung weight, increases strength, and minimizes the number of parts, preventing motor deformation from excessive loads and enhancing ride comfort by distributing vehicle body loads efficiently.
Implementation Method 1
a first arm portion that is formed integrally with a speed reduction portion casing forming an outer shape of the speed reduction portion, that projects in a direction perpendicular to the axis from the speed reduction portion casing, and that has its tip end pivotally couplable to a vehicle body-side member via a ball joint
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An in-wheel motor drive unit (11) includes: a motor portion (11A) that is placed on one side in the direction of the axis of the in-wheel motor drive unit; a wheel hub portion (11C) that is placed on the other side in the direction of the axis of the in-wheel motor drive unit; a speed reduction portion (11B) that is placed between the motor portion and the wheel hub portion and that reduces the speed of output rotation of the motor portion to transmit the resultant output rotation to the wheel hub portion; and a first arm portion (34) that is formed integrally with a speed reduction portion casing (33) forming the outer shape of the speed reduction portion, that projects in a direction perpendicular to the axis from the speed reduction portion casing, and that has its tip end pivotally coupled to a vehicle body-side member.