In-Wheel Motor Reducer Layout for Steering and High Reduction Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional in-wheel motor drive systems with parallel twin-shaft reducers lack sufficient speed reduction ratio, and those with multiple shaft reducers face space constraints within the wheel, preventing proper steering due to the placement of motors and reducers directly above and below the axle.
Innovation Solution
A quadruple-shaft parallel shaft gear reducer is used, with intermediate shafts positioned above the wheel hub, creating space below for a suspension member and allowing the steering axis to intersect, enabling suitable steering of the wheel and motor drive device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a parallel twin-shaft reducer is used, then the device complexity is reduced, but the speed reduction ratio is insufficient
Solution Approach 1:
The reducer is divided into multiple independent shafts (input shaft, intermediate shafts, output shaft) that can be arranged in different spatial configurations. This segmentation allows the use of a quadruple-shaft parallel shaft gear reducer with sufficient speed reduction ratio while maintaining relatively simple device complexity through modular gear arrangements.
Solution Approach 2:
The patent transitions from a two-shaft to a four-shaft configuration by adding intermediate shafts, effectively utilizing additional dimensional space within the wheel. This dimensional expansion enables achieving sufficient speed reduction ratio without proportionally increasing device complexity.
2Speed
If multiple shaft reducers are used to achieve sufficient speed reduction ratio, then the speed reduction ratio is improved, but the space within the wheel is insufficient
Solution Approach 1:
The patent utilizes vertical space within the wheel by arranging the quadruple-shaft reducer with intermediate shafts positioned at different heights. The input shaft and output shaft are arranged above and below the wheel hub respectively, with intermediate shafts connecting them vertically, thereby achieving sufficient speed reduction ratio while fitting within the limited wheel volume.
Solution Approach 2:
The multiple shafts and gears are nested within the wheel structure in a compact arrangement. The intermediate shafts are positioned between the input and output shafts, creating a nested configuration that maximizes space utilization within the wheel while achieving the required speed reduction ratio.
3Speed
If motors and reducers are placed directly above and below the axle, then the speed reduction ratio is sufficient, but the steering capability is lost
Solution Approach 1:
The patent arranges the input shaft and output shaft above and below the wheel hub in the vertical dimension, rather than directly above and below the axle horizontally. This vertical arrangement creates space around the axle for the steering axis to intersect, enabling both sufficient speed reduction ratio and proper steering capability.
Solution Approach 2:
The reducer components are asymmetrically arranged relative to the wheel hub and axle positions. The intermediate shafts are positioned offset from the axle centerline, creating an asymmetric configuration that allows the steering axis to pass through the wheel while maintaining the vertical shaft arrangement for speed reduction.
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 steering properties by securing space below the motor drive device within the wheel, allowing for effective steering and achieving a sufficient reduction ratio.
Implementation Method 1
a parallel shaft gear reducer which reduces rotation of the motor and transmits this to the wheel hub
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A speed reducer unit (31) of an in-wheel motor drive device (10) includes: an input shaft (32) coupled to a motor rotating shaft (22); an output shaft (41) coupled to a wheel hub (12) and extending parallel to the input shaft; and one or more intermediate shafts (35, 38) extending parallel to the input shaft and the output shaft, and an input gear (33) coupled to the input shaft, a plurality of intermediate gears (34, 36, 37, 39) coupled to the intermediate shafts, and an output gear (40) coupled to the output shaft mesh with each other and configure a drive transmission path leading to the output gear from the input gear through the plurality of intermediate gears. When viewed in the axial direction of the intermediate shafts, an axis (O) of the output shaft, an axis (Nl) of at least one intermediate shaft (38), and an axis (M) of the input shaft are arranged in this order in the vehicle front-to-rear direction, and the axis (Nl) of the at least one intermediate shaft is disposed above the axis of the output shaft and the axis of the input shaft.