Compound Planetary Gear Set for Multispeed Transmission
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Solution Overview
Problem
Existing electrified vehicles lack an efficient multispeed automatic transmission system suitable for electric motors, which limits their ability to effectively power wheels across various driving conditions.
Innovation Solution
A multispeed automatic transmission system incorporating a compound planetary gear set with multiple sun gears, a non-input/output ring gear, and stepped long pinion gears, along with rotary connecting clutches, allows for selective engagement of sun gears and shifting between speeds to optimize power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional single-speed transmission is used in electrified vehicles, then the structure is simple, but the vehicle cannot effectively handle diverse driving conditions
Solution Approach 1:
The transmission system is segmented into multiple sun gears (first, second, third sun gears) with different functions, allowing selective engagement for different driving conditions. Each sun gear can be independently connected or disconnected, enabling the system to adapt to various speed and torque requirements without requiring a completely complex transmission structure
Solution Approach 2:
The compound planetary gear set serves multiple functions through its configurable architecture. The same basic structure can operate in different modes (direct connection, gear reduction, reverse) by simply changing which sun gears are engaged, making the transmission universally applicable to diverse driving conditions without needing multiple separate systems
2Productivity
If a multispeed automatic transmission is implemented, then power transmission efficiency across various speeds is improved, but the transmission size and complexity increase
Solution Approach 1:
Multiple planetary gear sets are merged into a single compound planetary gear set structure. The first, second, and third planetary gear sets share common components (ring gear, carrier, pins), allowing the system to achieve multiple speed ratios while minimizing the number of separate components. This merging reduces overall complexity compared to using three separate planetary gear sets
Solution Approach 2:
The transmission system dynamically reconfigures its gear ratios by selectively engaging or disconnecting specific sun gears through clutches and brakes. This dynamic adaptability allows the system to optimize power transmission efficiency for different operating conditions without requiring physical changes to the basic structure, maintaining relatively simple hardware while achieving complex functionality
3Adaptability or versatility
If multiple sun gears are used in the compound planetary gear set, then speed variability is improved, but manufacturing complexity increases
Solution Approach 1:
Different sun gears have different local qualities - the first sun gear is configured for direct connection, the second for intermediate gearing, and the third for reverse. This local differentiation allows each component to be optimized for its specific function while maintaining compatibility with the overall system architecture, simplifying manufacturing compared to making every component identical yet multifunctional
Solution Approach 2:
The planetary gear sets are nested within a compact structure where the second planetary gear set is positioned within the first, and the third within the second. This nesting arrangement allows multiple sun gears to be accommodated in a limited space with shared components, reducing the overall manufacturing complexity compared to separate assemblies
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 enables efficient power transmission across multiple speeds, enhancing the vehicle's ability to handle diverse driving situations while minimizing transmission size, complexity, and cost.
Implementation Method 1
The compound planetary gear set includes multiple sun gears and a non-input/output ring gear, a long pinion gear meshed therebetween
Data Source
AI summary
A transmission includes a compound planetary gear set. The compound planetary gear set includes multiple sun gears and a non-input/output ring gear, a long pinion gear meshed therebetween, and an output planetary carrier carrying the long pinion gear. The long pinion gear includes multiple steps, and is meshed with the sun gears respectively at the steps and with the non-input/output ring gear at one step. With each sun gear alternatively being input-only or non-input/output, the sun gears are selectively input-only one at a time. Moreover, the non-input/output ring gear is anti-rotary and the output planetary carrier is output-only when the sun gears are input-only one at a time.