In-wheel Two-stage Speed Reduction for Torque and Size
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Solution Overview
Problem
Conventional in-wheel working devices for electric vehicles require large motor diameters to increase drive torque, leading to increased wheel size, necessitating a compact speed reduction solution to reduce motor size while maintaining or enhancing driving force.
Innovation Solution
A compact two-stage speed reduction device is implemented, comprising a motor part, a first speed reduction part with a planetary gear set, and a second speed reduction part, which includes a sun gear, planetary gear, carrier, and counter gear, allowing for axial connection and gear ratio-based speed reduction, thereby reducing motor size while increasing driving force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a large motor diameter is used to increase drive torque, then the driving force is improved, but the wheel size is increased
Solution Approach 1:
A two-stage speed reduction device is introduced as an intermediary mechanism between the motor and the wheel. The first speed reduction part (planetary gear set) and second speed reduction part (counter gear set) work together to reduce motor speed and increase torque before power is transmitted to the wheel, allowing a smaller motor to achieve the required drive torque without increasing wheel size
Solution Approach 2:
The speed reduction device changes the rotational speed and torque parameters through two stages of gear reduction. The planetary gear set provides the first stage of speed reduction with a specific gear ratio, and the counter gear set provides the second stage, collectively transforming the motor's high-speed low-torque output into low-speed high-torque output suitable for wheel drive
2Length of moving object
If a speed reduction device is added to reduce motor size, then the motor diameter is reduced, but the device complexity is increased
Solution Approach 1:
The speed reduction function is segmented into two distinct stages: the first speed reduction part using a planetary gear set and the second speed reduction part using a counter gear set. This segmentation allows each stage to be optimized independently and simplifies the overall design by breaking down the complex speed reduction requirement into manageable sub-functions
Solution Approach 2:
The planetary gear set is nested within the counter gear set arrangement, with the planetary gear carrier connected to the counter gear input shaft. This nested configuration allows both speed reduction stages to be compactly integrated, reducing the overall axial length and simplifying the structural layout while maintaining the two-stage reduction function
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 two-stage speed reduction device effectively reduces the motor size while doubling the driving force, improving design flexibility, reducing weight, and maintaining compatibility with existing chassis parts, while also allowing for a wider range of speed reduction ratios.
Implementation Method 1
a planetary gear configured to rotate along a circumference of the sun gear
Implementation Method 2
configured to perform speed reduction through a gear ratio while rotating with the carrier
Data Source
AI summary
An in-wheel working device may include a motor part configured to generate power, a first speed reduction part including a sun gear connected to a driving shaft of the motor part and configured to rotate with the driving shaft, a planetary gear configured to rotate along a circumference of the sun gear, and a carrier configured to rotate with the planetary gear, a second speed reduction part installed in series to the first speed reduction part, and configured to perform speed reduction through a gear ratio while rotating with the carrier axially connected to the second speed reduction part, a hub part spline-coupled to the second speed reduction part, and configured to rotate with the second speed reduction part, and a wheel member connected to the hub part, and configured to rotate with the hub part.