Wheel Hub Power Transmission Layout With Two-Stage Reduction
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Solution Overview
Problem
Existing wheel drive units for eco-friendly vehicles are bulky, causing interference with vehicle parts and requiring design changes, and in-wheel motor systems with reducers face issues with durability and ride comfort due to increased unsprung mass and power consumption.
Innovation Solution
A compact power transmission device with a reduced-size reducer and electric motor, utilizing a simple gear configuration to achieve efficient power transmission, minimizing road impact on the electric motor, and integrating components to reduce weight and improve ride comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a planetary gear set is used as a reducer in an in-wheel motor system, then power transmission efficiency is improved, but the device size and weight increase making it difficult to arrange components in the wheel hub
Solution Approach 1:
The patent divides the reducer into two separate stages: a first reducer (planetary gear set) and a second reducer (bevel gear set). This segmentation allows each reducer to be smaller and more specialized, fitting within the wheel hub space while maintaining high power transmission efficiency through the combined reduction ratio.
Solution Approach 2:
The patent changes the spatial arrangement by using a bevel gear set for the second reduction stage, which transmits power in a different direction (at an angle). This dimensional change in power transmission allows compact packaging of the reducer components within the limited wheel hub volume.
2Speed
If a large-capacity electric motor is used to compensate for the lack of a reducer, then high-speed driving performance is improved, but power consumption increases and driving distance is limited
Solution Approach 1:
The patent changes the rotational speed parameter through a two-stage reduction mechanism. The first reducer provides a reduction ratio of 1:2.5 to 1:3.5, and the second reducer provides 1:1.5 to 1:2.5, achieving a total reduction ratio of 1:3.75 to 1:8.75. This allows a small-capacity high-speed electric motor to operate efficiently while delivering the required wheel speed and torque.
3Device complexity
If the electric motor directly drives the wheel hub, then the structure is simplified, but road impact is directly transmitted to the electric motor reducing durability
Solution Approach 1:
The patent introduces a two-stage reducer system as an intermediary between the electric motor and the wheel hub. This intermediary mechanism decouples the electric motor from direct road impacts while still transmitting driving force, thereby protecting the motor from shock loads and improving durability without significantly increasing structural complexity.
4Power
If the size and weight of the electric motor are increased, then launch performance is improved, but unsprung mass increases deteriorating ride comfort
Solution Approach 1:
The patent replaces the need for a large-capacity electric motor with a mechanical advantage approach. By using a two-stage reducer system with a total reduction ratio of 1:3.75 to 1:8.75, a small-capacity electric motor can generate sufficient launch torque through mechanical multiplication, thereby reducing unsprung mass and improving ride comfort while maintaining launch performance.
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 solution enables efficient power transmission, improved durability, and enhanced ride comfort by reducing the size and weight of the wheel drive unit, allowing for high-efficiency launch and high-speed performance with a small-capacity electric motor.
Implementation Method 1
a driving member operatively connected to the power source and including a driving gear, a driven member including a driven gear engaged with the driving gear
Data Source
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AI summary
A power transmission device is disclosed. The power transmission device may include a power portion including a power generating portion including a power source generating power, and a fixing portion extending from the power generating portion in an axial direction, a driving member operatively connected to the power source and including a driving gear, a driven member including a driven gear engaged with the driving gear, a rotating member coupled to the driven member and rotating with the driven member, and an output member having a rotating wheel mounted thereon, defining an axial width, coupled to the rotating member, and rotating with the rotating member, the power source may include a power source shaft, and the power source shaft may be disposed in a range of -25 ° to 25 ° with respect to a radial direction of a rotating wheel.