Multi-Stage Transmission with Four Planetary Gear Sets
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Solution Overview
Problem
Multi-stage transmissions face challenges in maximizing fuel efficiency due to increased complexity and weight with more shift stages, leading to difficulties in packaging and reduced transfer efficiency, while also generating noise.
Innovation Solution
A multi-stage transmission design incorporating four planetary gear sets and six shifting elements, including clutches and brakes, to achieve ten forward and one reverse gear stage with a minimal component count and straightforward configuration, optimizing engine operation and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of shift stages is increased to improve fuel efficiency, then the engine can operate at optimal driving points, but the number of internal components increases leading to packaging difficulties and increased weight
Solution Approach 1:
The patent merges multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission system where gear sets share common components such as the sun gear, carrier, and ring gear. This consolidation achieves ten forward stages and one reverse stage while minimizing the total number of discrete components compared to using separate gear sets for each stage.
Solution Approach 2:
The planetary gear sets are designed with multi-functional rotary elements that serve multiple purposes. For example, the sun gear, carrier, and ring gear of each planetary gear set can function as input, output, or fixed elements depending on the engagement state of clutches and brakes, enabling a single gear set to contribute to multiple gear stages rather than requiring dedicated gear sets for each function.
2Use of energy by moving object
If the number of shift stages is increased to improve fuel efficiency, then the engine can operate at optimal driving points, but the weight of the transmission increases
Solution Approach 1:
The transmission system combines four planetary gear sets into one unified structure where components are shared across multiple gear sets. This merging reduces the cumulative weight that would result from having separate, non-sharing gear sets for each stage, achieving ten forward and one reverse stage with minimized total weight.
Solution Approach 2:
The planetary gear sets are arranged in a nested or compact configuration where the rotary elements of one gear set are positioned to interact with or share space with elements of adjacent gear sets. This nesting allows for space-efficient packaging and reduces overall transmission volume and weight while maintaining all required gear stages.
3Adaptability or versatility
If the number of shift stages is increased to improve fuel efficiency, then more gear ratios are available, but the transmission size and packaging difficulty increase
Solution Approach 1:
The patent merges four planetary gear sets into a single compact transmission assembly where gear sets share common rotary elements and housing space. This consolidation achieves ten forward stages and one reverse stage within a reduced footprint compared to using independent gear sets for each stage, solving the packaging difficulty associated with high-stage transmissions.
Solution Approach 2:
The planetary gear sets are nested or closely integrated such that the rotary elements of adjacent gear sets are positioned to share space or interact directly. This nesting arrangement enables the transmission to fit within a compact engine compartment while providing all necessary gear stages for optimal fuel efficiency across various driving conditions.
4Adaptability or versatility
If more planetary gear sets are used to achieve more shift stages, then gear ratio options increase, but the cost of the transmission increases
Solution Approach 1:
The transmission merges four planetary gear sets into one integrated system with shared components, reducing the total number of parts that need to be manufactured, assembled, and quality-checked. This consolidation lowers manufacturing complexity and cost while still achieving ten forward and one reverse stage, making the high-stage transmission more cost-effective compared to using separate gear sets for each stage.
Data Source
AI summary
Disclosed herein is a multi-stage transmission for a vehicle. The multi-stage transmission includes an input shaft IN and an output shaft OUT; a first planetary gear set PG1, a second planetary gear set PG2, a third planetary gear set PG3, and a fourth planetary gear set PG4 installed between the input shaft IN and the output shaft OUT so as to transfer a torque and each including three rotary elements; and six shifting elements connected to the rotary elements of the first to fourth planetary gear sets.