In-Wheel Motor Gear Reducer Layout for Suspension Linkage
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Solution Overview
Problem
Conventional in-wheel motor systems with parallel triple-shaft gear reducers face challenges in linking the motor to the suspension due to motor size constraints, which affect the suspension's stability under bending moments, and struggle to maintain a sufficient speed reduction ratio while accommodating a ball joint in the narrow hollow area of the wheel assembly.
Innovation Solution
The in-wheel motor driving device employs a parallel multi-shaft gear speed reducer with an output shaft at the wheel's center, featuring intermediate gears with larger diameters than the output gear, allowing a closer linkage point to the wheel hub and creating space for a ball joint below the output gear, thus improving suspension stability and maintaining a sufficient speed reduction ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a parallel triple-shaft gear reducer is used to achieve a greater speed reduction ratio, then the speed reduction ratio is improved, but the motor and reducers are disposed immediately above and below the axle, making it difficult to link the lower part of the in-wheel motor to the suspension in the narrow hollow area
Solution Approach 1:
The patent changes the spatial arrangement by offsetting the output shaft from the axial centerline to the radial direction. This dimensional repositioning creates clearance in the axial direction, allowing the lower part of the motor to be linked to the suspension in the narrow hollow area while maintaining the triple-shaft gear reducer configuration for sufficient speed reduction ratio.
Solution Approach 2:
The output shaft is positioned asymmetrically relative to the axial centerline of the wheel assembly. This asymmetric placement optimizes the use of available space in the hollow area, enabling suspension linkage while preserving the mechanical advantages of the parallel triple-shaft gear reducer system.
2Force
If the motor diameter is increased to obtain desired motor torque, then the motor torque is improved, but the distance between the input shaft and output shaft decreases, preventing intermediate gears from having adequate diameters
Solution Approach 1:
By offsetting the output shaft radially from the axial centerline, the patent creates additional radial space that allows intermediate gears to have adequate diameters even when the motor has a larger diameter for sufficient torque production. This spatial reconfiguration resolves the conflict between motor size and gear dimensions.
3Ease of operation
If the linkage point is located radially outside of the output gear to link the in-wheel motor and suspension, then the linkage is achieved, but the linkage point is located away from the axle, adversely affecting the suspension under bending moment input
Solution Approach 1:
The asymmetric positioning of the output shaft radially offset from the axial centerline allows the linkage point to be positioned optimally. This creates a configuration where the linkage can be achieved while keeping the linkage point closer to the axle, thereby maintaining suspension stability under bending moment input.
Solution Approach 2:
The patent optimizes the local positioning of the output shaft and linkage point to achieve the best compromise between linkage connectivity and suspension stability. By carefully selecting the radial offset position, the system achieves effective linkage while minimizing the adverse effects of bending moments on the suspension.
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 brings the linkage point closer to the wheel hub, reducing the adverse effect of bending moments on the suspension and providing a sufficient speed reduction ratio without sacrificing space for the ball joint, enhancing the overall structural integrity and efficiency of the in-wheel motor system.
Implementation Method 1
an input gear coupled to the input shaft, an output gear coupled to the output shaft, and a plurality of intermediate gears coupled to the intermediate shaft(s). The input gear, the intermediate gears, and the output gear are engaged with one another to form a driving force transmission path
Data Source
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AI summary
The speed reduction unit (31) of the in-wheel motor driving device (10) includes an input shaft (32), an output shaft (41) coupled to a wheel hub (12) and extending in parallel with the input shaft, one or more intermediate shafts (35, 38) extending in parallel with the input shaft and output shaft, an input gear (33) coupled to the input shaft, an output gear (40) coupled to the output shaft, and a plurality of intermediate gears (34, 36, 37, 39) coupled to the intermediate shaft. The input gear, intermediate gears, and output gear are engaged with one another to form a driving force transmission path connecting the input gear to the output gear through the intermediate gears. At least one intermediate gear (37) of the intermediate gears has a diameter greater than the diameter of the output gear.