Multi-stage Transmission Using Four Planetary Gear Devices
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Solution Overview
Problem
Increasing the number of gear shift stages in vehicle transmissions to improve fuel economy results in a higher number of parts and a more complex structure, leading to increased costs, weight, and reduced efficiency.
Innovation Solution
A multi-stage transmission design utilizing four planetary gear devices and six gear shift elements, including clutches and brakes, to achieve 10 forward and 1 reverse stages with a minimal number of parts and a simple structure, optimizing gear ratios for efficient engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of gear shift stages is increased to improve fuel economy, then the engine can operate at optimal points and fuel efficiency improves, but the number of parts increases and the structure becomes more complex
Solution Approach 1:
The patent combines multiple planetary gear devices (first, second, third, and fourth planetary gear devices) into a single integrated transmission system. These planetary gear devices share common rotary elements and shafts, merging their functions to achieve 10 forward stages and 1 reverse stage without requiring separate gear trains for each stage, thus reducing overall structural complexity while maintaining high gear multiplication capability
Solution Approach 2:
The planetary gear devices are designed with multi-functionality where rotary elements serve multiple purposes. For example, the third rotary element of the first planetary gear device connects to the first rotary element of the second planetary gear device, and the fourth rotary element connects to the sixth rotary shaft which in turn connects to multiple other elements. This universal design allows a single planetary gear device to contribute to multiple gear stages, reducing the total number of parts needed
2Use of energy by moving object
If the number of gear shift stages is increased to improve fuel economy, then the engine can operate at lower RPM ranges reducing noise, but the weight of the transmission increases
Solution Approach 1:
The transmission system merges multiple planetary gear devices into a compact configuration where they share common shafts and rotary elements. This consolidation reduces the cumulative weight that would result from having separate, non-sharing gear trains for each stage, achieving 10 forward stages with minimized total weight
Solution Approach 2:
The planetary gear devices are arranged in a nested or compact configuration where smaller gear components are positioned within or adjacent to larger ones. The rotary elements are interconnected in a way that creates a space-efficient layout, allowing multiple gear stages to occupy minimal volume and weight while maintaining full functionality
3Use of energy by moving object
If the number of gear shift stages is increased to improve fuel economy, then the engine can operate more efficiently, but the number of parts increases leading to higher costs
Solution Approach 1:
The patent merges the functions of multiple planetary gear devices into a single integrated system where rotary elements and shafts are shared across devices. This consolidation achieves 10 forward stages and 1 reverse stage using a minimized set of parts, directly reducing manufacturing costs compared to conventional designs that would require more discrete components
Solution Approach 2:
Each planetary gear device is designed with universal, multi-functional rotary elements that participate in multiple gear stage formations. The third rotary element of one device connects to the first rotary element of the next device, creating a chain of universal connections that reduces the total number of unique parts needed while maintaining the ability to generate all required gear ratios
4Use of energy by moving object
If the number of gear shift stages is increased to improve fuel economy, then the engine can operate at optimal points, but the transfer efficiency of the transmission decreases
Solution Approach 1:
The integrated planetary gear device design reduces the number of separate gear meshes and power transmission paths compared to conventional multi-stage transmissions. By merging functions and using shared rotary elements, the system minimizes energy losses at each transmission interface, maintaining high transfer efficiency across all 10 forward stages and 1 reverse stage
Data Source
AI summary
A multi-stage transmission for vehicles includes an input shaft for receiving power from an engine, an output shaft for outputting the power, a first planetary gear device, a second planetary gear device, a third planetary gear device, and a fourth planetary gear device. Each of the planetary gear devices has three rotary elements, a first rotary shaft connected to the input shaft, a second rotary shaft, a third rotary shaft, a fourth rotary shaft, a fifth rotary shaft, a sixth rotary shaft, a seventh rotary shaft, and an eighth rotary shaft connected to the third rotary element of the third planetary gear device, to the second rotary element of the fourth planetary gear device, and to the output shaft.