Nine-Speed Planetary Transmission Layout for Lower AMT Weight
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Solution Overview
Problem
Existing vehicle transmissions, particularly automated manual transmissions (AMT) for trucks, face challenges with bulky dimensions and weight due to the need to withstand high radial forces and forces on gear teeth, which affects efficiency and cost-effectiveness.
Innovation Solution
A transmission design utilizing two planetary gear sets to provide nine forward gears with varying speed ratios, including a configuration that allows for compact and efficient gear shifting with two actuators, reducing weight and complexity while maintaining high torque-to-weight ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional AMT with multiple planetary gear sets is used to provide multiple forward gears, then the number of available gear ratios increases, but the transmission weight and bulkiness increase due to high radial forces and gear tooth forces
Solution Approach 1:
Each planetary gear set is designed to provide three forward speeds with different speed ratios (first forward speed reduction larger than second forward speed reduction, plus one direct speed), allowing a single planetary gear set to perform multiple gear ratio functions. This multi-functionality enables two planetary gear sets to provide nine forward gears instead of requiring more traditional planetary gear sets
Solution Approach 2:
The output of one planetary gear set is drivingly connected to the input of the other planetary gear set, merging their functions to achieve a compact nine-speed transmission. This combination allows the system to provide nine forward gears by utilizing the three speed ratios of each planetary gear set in sequence, reducing the total number of components needed compared to traditional designs
2Productivity
If more planetary gear sets are used to provide more forward gears, then the gear sequence and torque paths are improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
Each planetary gear set is configured to provide three forward speeds with different speed ratios through two forward speed reductions and one direct speed, enabling a single planetary gear set to perform the work of multiple traditional planetary gear sets. This universality allows the system to achieve nine forward gears with only two planetary gear sets, reducing device complexity
Solution Approach 2:
Each planetary gear set is individually shiftable between its three forward speeds, allowing dynamic selection of speed ratios based on torque demand and vehicle operating conditions. This dynamic shifting capability enables optimized energy efficiency without requiring a fixed, complex mechanical structure with multiple planetary gear sets
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves a high-efficiency, cost-effective transmission with improved energy efficiency and reduced weight by utilizing two planetary gear sets to provide nine forward gears with optimized gear sequences and smooth gear shifts.
Implementation Method 1
each planetary gear set is configured to provide a first and a second forward speed reduction and one direct speed with a one to one (1:1) speed ratio
Data Source
Figure 1
Figure 2a~2b
Figure 2c~2d
AI summary
The invention relates to a transmission (1) for a vehicle (100), wherein the transmission is configured to provide nine forward gears in sequence from the first gear to the ninth gear, the transmission comprising: - a first (10) and a second (20) planetary gear set comprising a respective input (I10, I20) and output (O10, O20), wherein: - the first and second planetary gear sets (10, 20) are configured axially in series, wherein the output (O10) of one of the first and second planetary gear sets (10, 20) is drivingly connected to the input (I20) of the other one of the first and second planetary gear sets (10, 20); - each planetary gear set (10, 20) is configured to provide a first and a second forward speed reduction and one direct speed with a one to one (1:1) speed ratio, the first forward speed reduction being larger than the second forward speed reduction, thereby providing three forward speeds with different speed ratios; and - each planetary gear set (10, 20) is configured to be individually shiftable between its three forward speeds; - wherein the transmission is configured to provide: - the first to third gears by utilizing the first forward speed reduction of the second planetary gear set (20) and by alternating the three forward speeds with different speed ratios of the first planetary gear set (10); - the fourth to fifth gears by utilizing the first forward speed reduction of the first planetary gear set (10) and by alternating the second planetary gear set (20) between its second forward speed reduction and its direct speed; - the sixth to seventh gears by utilizing the second forward speed reduction of the first planetary gear set and by alternating the second planetary gear set between its second forward speed reduction and its direct speed; - the eighth to ninth gears by utilizing the direct speed of the first planetary gear set and by alternating the second planetary gear set between its second forward speed reduction and its direct speed.