Planetary Gear Transmission Layout for Multi-Ratio EV Drive
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Solution Overview
Problem
Existing power transmission devices for electric automobiles with planetary gear reducers face complexity and durability issues due to the need for multiple reduction ratios, leading to increased volume and reduced durability.
Innovation Solution
A power transmission device comprising a motor, two reducers with sun gears, planetary gears, and clutches, along with a differential gear, allowing for variable speed reduction through synchronized rotation of planetary gears and engagement/disengagement mechanisms to achieve multiple reduction ratios with a simplified structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a planetary gear reducer with multiple reduction ratios is provided, then the efficiency according to traveling conditions is improved, but the structure becomes complicated and volume increases
Solution Approach 1:
The patent employs a movable carrier that can be positioned at different locations around the sun gear, allowing the planetary gear system to dynamically change its configuration. By moving the carrier between different positions, the system achieves multiple reduction ratios without requiring multiple complete planetary gear sets, thus maintaining structural simplicity while providing adaptability for different traveling conditions
2Adaptability or versatility
If a planetary gear reducer with multiple reduction ratios is provided, then the efficiency according to traveling conditions is improved, but the volume occupied by the reducer increases
Solution Approach 1:
The patent implements a nested configuration where the planetary gears are arranged concentrically around the sun gear, and the movable carrier can be positioned within the existing gear structure. This nesting approach allows multiple reduction ratios to be achieved within a compact volume by utilizing the same spatial envelope for different gear configurations, rather than requiring separate gear sets for each ratio
3Volume of stationary object
If the structure of the reducer is simplified to reduce volume, then the volume is reduced, but the durability is deteriorated
Solution Approach 1:
The patent incorporates a clutch mechanism that can disengage the planetary gear system from the drivetrain under high-stress conditions. This clutch acts as a protective element that prevents excessive loads from being transmitted to the simplified gear structure, thereby cushioning the system against potential damage and maintaining durability despite the reduced structural complexity
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
Enables efficient and durable power transmission with multiple reduction ratios, reducing the complexity and volume of the reducer while improving durability, allowing for optimal efficiency across varying driving conditions.
Implementation Method 1
a first planetary gear disposed outside of the first sun gear and engaged with the first sun gear
Data Source
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AI summary
A power transmission device includes: a motor to drive a rotary shaft; a first reducer to receive torque from the rotary shaft; a second reducer to receive torque from the first reducer; and a first clutch disposed outside the second reducer to connect and disconnect the second reducer and an external component.