Multi-stage Transmission with Planetary Gear Sets
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Solution Overview
Problem
Current vehicle transmissions are inefficient due to complex constructions and a limited number of shifting stages, which hinders improved fuel efficiency.
Innovation Solution
A multi-stage transmission design incorporating three planetary gear sets with specific rotary elements and shifting elements, allowing for at least nine forward and one reverse shifting stage with a simple construction and low weight, utilizing a Ravigneaux-type compound planetary gear set and strategically positioned brakes and clutches for efficient gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmission uses a complex construction with multiple parts to achieve more shifting stages, then the number of shifting stages increases, but the device complexity and weight increase
Solution Approach 1:
The patent combines three planetary gear sets (first, second, and third) into a single integrated transmission system where the rotary elements of different gear sets are directly connected to each other. This merging approach enables the transmission to achieve ten forward shifting stages and one reverse shifting stage without requiring separate transmissions for each function, thereby increasing the number of shifting stages while controlling construction complexity.
Solution Approach 2:
The planetary gear sets are designed with rotary elements that serve multiple functions - the same rotary elements are used for both forward shifting and reverse shifting operations. The first planetary gear set, second planetary gear set, and third planetary gear set share common rotary elements that can be selectively fixed or connected through brakes and clutches, enabling a single transmission system to perform multiple shifting functions efficiently.
2Adaptability or versatility
If a transmission uses more parts to provide more shifting stages, then the number of shifting stages increases, but the weight increases
Solution Approach 1:
The transmission merges three planetary gear sets into one compact unit where rotary elements are directly connected between gear sets. This consolidation eliminates the need for separate transmissions for forward and reverse operations, reducing the overall weight while achieving ten forward shifting stages and one reverse shifting stage in a single lightweight transmission system.
Solution Approach 2:
The planetary gear sets are arranged in a nested configuration where the rotary elements of one gear set are directly connected to rotary elements of adjacent gear sets. The first rotary element of the first planetary gear set connects to the second rotary element of the third planetary gear set, creating a compact nested structure that minimizes weight while maximizing shifting capability.
3Device complexity
If a transmission uses a simple construction with fewer parts, then the weight and complexity decrease, but the number of shifting stages is limited
Solution Approach 1:
The patent achieves a simple construction by merging three planetary gear sets into one integrated system with direct connections between rotary elements. This simple merged design unexpectedly achieves ten forward shifting stages and one reverse shifting stage, proving that complexity is not necessary to achieve high shifting capability when gear sets are properly integrated.
Solution Approach 2:
The transmission employs dynamic control through brakes and clutches that can selectively fix or connect rotary elements during operation. The first brake, second brake, first clutch, second clutch, third clutch, and fourth clutch enable dynamic reconfiguration of the planetary gear sets, allowing a simple static construction to achieve complex dynamic shifting behavior with ten forward stages and one reverse stage.
4Adaptability or versatility
If a transmission uses selective fixing and connecting of rotary elements to achieve various shifting stages, then the number of shifting stages increases, but the device complexity increases
Solution Approach 1:
The brakes and clutches serve universal functions across multiple planetary gear sets. The first brake can fix rotary elements in both the first and second planetary gear sets, the first clutch can connect rotary elements across different gear sets, and this multi-functionality reduces the overall control mechanism complexity while enabling ten forward shifting stages and one reverse shifting stage.
Data Source
AI summary
A multi-stage transmission is disclosed. The multi-stage transmission includes: two simple planetary gear sets, each including three rotary elements; one compound planetary gear set including four rotary elements; and six shifting elements. Since ten forward shifting stages and one reverse shifting stage can be accomplished with a relatively small number of parts, a simple construction and a low weight, the multi-stage transmission provides a further improved speed ratio for the driving conditions of the vehicle, thereby improving the fuel efficiency of the vehicle.