Planetary Multi-Speed Gearbox With Four Clutches for Smooth Shifting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-speed transmissions with compound planetary gear sets are space inefficient, complex, and costly, while those with fewer operating gears exhibit wide gear ratio spreads causing torque interruptions during shifting transients, and high ring gear speeds lead to gear degradation.
Innovation Solution
A multi-speed gearbox with a planetary assembly featuring a first gear set rotationally coupled to a second gear set, utilizing four clutches to achieve at least four gear stages in a compact package, with a one-way clutch connecting the input shaft to the first sun gear and another one-way clutch connecting the second sun gear to the output shaft, and a carrier in the second gear set functioning as both input and output, while grounding the ring gear to reduce gear speeds and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a compound planetary gear set with multiple clutches is used, then multiple gear stages can be achieved, but the transmission becomes space inefficient and complex
Solution Approach 1:
The planetary assembly is segmented into a first planetary gear set and a second planetary gear set, each with simplified structures. The first gear set provides first and second gear stages, while the second gear set provides third and fourth gear stages. This segmentation allows achieving multiple gear stages without requiring a complex single compound planetary gear set, thereby reducing overall device complexity while maintaining adaptability for multiple gear ratios.
2Device complexity
If transmissions with fewer operating gears are used, then the structure is simpler, but wide gear ratio spreads cause torque interruptions during shifting transients
Solution Approach 1:
The transmission is designed with four distinct gear stages with progressively optimized gear ratios. The first gear ratio is 4.82:1, the second is 2.98:1, the third is 1.71:1, and the fourth is 1.00:1. This local optimization of gear ratio distribution ensures that each gear stage transition involves a manageable ratio change, preventing wide gear ratio spreads and the associated torque interruptions during shifting transients, thereby improving shifting smoothness and reliability.
3Power
If high ring gear speeds are used, then power transmission is efficient, but gear degradation increases
Solution Approach 1:
The transmission employs a dynamic clutch control system that selectively engages and disengages clutches based on operating conditions and desired gear stages. This dynamic control allows the system to optimize power transmission efficiency by engaging appropriate clutches for each gear stage while simultaneously managing ring gear speeds to prevent excessive velocities that would lead to gear degradation. The dynamic adaptation ensures both power efficiency and gear durability are maintained under varying operational demands.
Data Source
AI summary
Multi-speed gearbox systems and methods. A multi-speed gearbox, in one example, includes a planetary assembly with a first gear set rotationally coupled to a second gear set. The multi-speed gearbox further includes a first clutch configured to selectively couple a first sun gear of the first gear set to an input shaft configured to rotationally couple to an electric machine and a second clutch configured to selectively couple a first sun gear of the second gear set to an output shaft.