Multi-stage Transmission with Shared Planetary Elements
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Solution Overview
Problem
Current multi-stage transmissions face challenges in achieving a high number of shifting stages with a minimal number of parts and a simple configuration, leading to increased weight, cost, and reduced efficiency, while also compromising engine quietness and fuel efficiency.
Innovation Solution
A multi-stage transmission design utilizing four planetary gear devices with three rotary elements each, and six shifting elements to achieve at least ten forward and one reverse shifting stage, with a configuration that minimizes parts and complexity, allowing for optimal engine operation points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of shifting stages is increased to improve fuel efficiency, then fuel efficiency is improved, but the number of internal parts increases leading to increased weight and complexity
Solution Approach 1:
The patent merges multiple planetary gear devices into a single integrated transmission system where four planetary gear devices share common rotary elements and shifting elements. The first and second planetary gear devices share the first rotary element, while the third and fourth planetary gear devices share the second rotary element. This consolidation allows achieving ten forward shifting stages and one reverse shifting stage with a reduced number of independent components compared to traditional multi-stage transmissions.
Solution Approach 2:
Each planetary gear device is designed with multi-functionality where the same rotary elements serve multiple purposes across different gear devices. The first rotary element functions as both the sun gear for the first planetary gear device and the ring gear for the second planetary gear device. Similarly, the second rotary element serves as the ring gear for the third planetary gear device and the sun gear for the fourth planetary gear device. This universal design enables multiple shifting stages using the same physical components.
2Use of energy by moving object
If the number of shifting stages is increased to improve fuel efficiency, then fuel efficiency is improved, but the weight of the transmission increases
Solution Approach 1:
The transmission system combines four planetary gear devices into a compact configuration where components are shared across multiple devices. The first rotary element is permanently connected to both the input shaft and the second rotary element of the third planetary gear device. The third rotary element of the third planetary gear device is permanently connected to both the second rotary element of the fourth planetary gear device and the output shaft. This merging reduces the total weight by eliminating redundant components.
3Use of energy by moving object
If the number of shifting stages is increased to improve fuel efficiency, then fuel efficiency is improved, but the cost of the transmission increases
Solution Approach 1:
The patent employs six shifting elements (first to sixth clutches) that control variable connection structures across multiple planetary gear devices. These shifting elements manage the engagement and disengagement of rotary elements to achieve ten forward shifting stages and one reverse shifting stage. By using a limited number of multi-functional clutches rather than dedicated components for each shifting stage, the manufacturing cost is reduced while maintaining high shifting stage capability.
4Use of energy by moving object
If the number of shifting stages is increased to improve fuel efficiency, then fuel efficiency is improved, but the quietness of the vehicle deteriorates
Solution Approach 1:
The transmission system employs dynamic shifting mechanisms where the six clutches can rapidly engage and disengage rotary elements to change gear ratios. This dynamic control allows the engine to operate at optimal RPM ranges for fuel efficiency while maintaining quiet operation by selecting appropriate gear stages that minimize engine noise and vibration transmission to the vehicle chassis.
Data Source
AI summary
A multi-stage transmission for vehicle may include an input shaft; and an output shafts; first to fourth planetary gear devices transmitting rotary force between the input and output shafts, each of them having three rotary elements; and at least six shifting elements connected to the rotary elements of the planetary gear devices; wherein first rotary element of the first planetary gear device is permanently connected to the input shaft and second rotary element of the third planetary gear device, second rotary element is installed to be fixable by any one of the shifting elements and variably connected to first rotary element of the third planetary gear device and first rotary element of the fourth planetary gear device, and third rotary element is variably connected to first rotary element of the second planetary gear device and permanently connected to second rotary element of the second planetary gear device.