In-wheel Bearing Unit with Offset Internal Gear for Compact Motor Integration
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Solution Overview
Problem
In-wheel motor systems face challenges in achieving a sufficient reduction ratio while minimizing component count and maintaining a compact design, particularly in ensuring a minimum ground height and accommodating an electric generator and wireless communication device within the limited space of a driving wheel supporting rolling bearing unit.
Innovation Solution
The driving wheel supporting rolling bearing unit incorporates an internal gear as a reduction gear, supported and fixed to the rotation side flange, allowing the input shaft to be offset from the center axis, enabling a larger diameter internal gear for increased reduction ratio without using a planetary reduction gear, and providing space for an electric generator and wireless communication device within the bearing unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a planetary reduction gear is used to achieve sufficient reduction ratio, then the reduction ratio is sufficient, but the number of components increases and the structure becomes complicated
Solution Approach 1:
The invention extracts the reduction gear function from the traditional planetary configuration and implements it using a simple pinion gear meshing with the inner peripheral surface of the hub. This extraction eliminates the complex planetary structure while maintaining the reduction ratio function, directly resolving the contradiction between sufficient reduction ratio and reduced component count.
2Power
If a planetary reduction gear is used, then the reduction ratio is sufficient, but the structure becomes complicated
Solution Approach 1:
The invention extracts the reduction gear function from the traditional planetary configuration and implements it using a simple pinion gear meshing with the inner peripheral surface of the hub. This extraction eliminates the complex planetary structure while maintaining the reduction ratio function, directly resolving the contradiction between sufficient reduction ratio and reduced component count.
3Volume of moving object
If the input shaft and output shaft are provided coaxially, then the planetary reduction gear can be compact, but it is difficult to ensure minimum ground height
Solution Approach 1:
The invention applies asymmetry by offsetting the pinion gear from the center axis of the hub. The pinion gear is positioned at a radial distance from the center, allowing the input shaft to be located away from the output axis. This asymmetric configuration enables the electric motor to be positioned lower, ensuring minimum ground height while maintaining compact overall dimensions.
4Force
If a shaft for transmitting driving force is connected to the center hole of the rotation side bearing ring member, then the driving force can be transmitted, but it is difficult to dispose the electric generator or wireless communication circuit in the limited space
Solution Approach 1:
The invention applies asymmetry by offsetting the pinion gear from the center axis of the hub. The pinion gear is positioned at a radial distance from the center, allowing the input shaft to be located away from the output axis. This asymmetric configuration enables the electric motor to be positioned lower, ensuring minimum ground height while maintaining compact overall dimensions.
Solution Approach 2:
The invention utilizes the radial dimension by positioning the pinion gear on the inner peripheral surface of the hub at a radial distance from the center. This dimensional change allows the input shaft to be located in the radial direction rather than coaxially, creating available space in the center region for accommodating the electric generator and wireless communication circuit.
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 allows for a sufficient reduction ratio with reduced components, maintaining a compact size and enabling the integration of an electric generator and wireless communication device without enlarging the device, thus enhancing the efficiency and performance of the in-wheel motor system.
Implementation Method 1
a plurality of rolling elements which are rollably provided between peripheral surfaces of the stationary side bearing ring member and the rotation side bearing ring member which face each other
Implementation Method 2
an internal gear which configures a reduction gear for transmitting a driving force of a driving source to the rotation side bearing ring member
Implementation Method 3
an electric generator including a stator and a rotor supported by the rotation side bearing ring member
Data Source
Figure 1
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Figure 3
AI summary
An internal gear constituting a transmission is supported and fixed in relation to a rotation-side flange provided to the outer end of a hub in the axial direction, and the hub is rotationally driven on the basis of the driving force inputted via the internal gear. As a result, it is not necessary to connect the driving shaft that rotationally drives the hub to the center hole of the hub, and thus a generator and a wireless communications device are disposed in a housing space that has a large space provided to the inner side of the hub in the axial direction.