Multi-speed Transmission Planetary Gear Speed Ratios
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional automatic transmissions face challenges in efficiently managing power transmission across a wide range of vehicle speeds, as many engines operate optimally within a narrow speed range, requiring transmissions that can adapt to various speed ratios for both low-speed acceleration and high-speed cruising.
Innovation Solution
The use of multiple gearing arrangements, including simple planetary gear sets and selective clutch and brake mechanisms, to impose specific speed relationships among input and output shafts, allowing for a variety of speed ratios and efficient power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmission uses a narrow range of speed ratios, then the device complexity is reduced, but the adaptability to different vehicle speeds deteriorates
Solution Approach 1:
The transmission is divided into multiple independent planetary gear sets (first, second, and third simple planetary gear sets), each capable of providing specific speed ratios. This segmentation allows the system to achieve a wide range of speed ratios by selectively engaging different gear sets, thereby improving adaptability without requiring a single overly complex gear train.
Solution Approach 2:
The transmission employs dynamic engagement and disengagement of clutch elements and brake elements to selectively activate different planetary gear sets based on vehicle speed requirements. This dynamic configuration allows the transmission to adapt to different vehicle speeds by changing which gear sets are active, maintaining versatility while managing complexity through controlled engagement rather than permanent mechanical connections.
2Adaptability or versatility
If multiple shift elements are used to provide various speed ratios, then the adaptability improves, but the device complexity increases
Solution Approach 1:
Each planetary gear set is designed to serve multiple functions by providing different speed ratios through selective engagement. The clutch elements and brake elements are configured to work with multiple gear sets, allowing a single shift element to influence several gear ratios. This multi-functionality reduces the total number of shift elements needed while maintaining a wide range of available speed ratios.
Solution Approach 2:
The patent combines multiple planetary gear sets into a single integrated transmission assembly where shared components (such as common clutch elements and brake elements) control multiple gear ratios simultaneously. By merging the control functions of multiple shift elements into fewer unified elements, the system achieves high adaptability with reduced complexity in the shifting mechanism.
3Ease of operation
If conventional clutch and brake elements are used for gear changes, then the ease of operation is maintained, but the productivity during gear changes deteriorates
Solution Approach 1:
The transmission system pre-configures the planetary gear sets and shift elements so that gear changes can be executed by simply engaging or disengaging pre-positioned clutch and brake elements. The mechanical arrangements are designed in advance to allow rapid transitions between gear ratios without requiring complex reconfiguration or manual intervention, thereby maintaining ease of operation while enabling fast gear changes.
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
This configuration enables the transaxle to provide a range of speed ratios, including eleven forward and one reverse, enhancing acceleration and fuel efficiency across different vehicle speeds while minimizing the need for multiple shift elements during gear changes.
Implementation Method 1
A first gearing arrangement fixedly imposes a linear speed relationship among the first shaft, the second shaft, the third shaft, and the fourth shaft. The first gearing arrangement may be, for example, first and second simple planetary gear sets
Data Source
AI summary
A transmission gearing arrangement produces eleven forward speed ratios and one reverse speed ratio by selective engagement of three shift elements in various combinations. One embodiment includes four simple planetary gear sets, four clutches, and two brakes. Another embodiment includes two axis transfer gear pairs, three simple planetary gear sets, four clutches, and two brakes. Each of these embodiments may include a one way brake such that the first shift is non-synchronous. A third embodiment includes four simple planetary gear sets, four brakes, and two clutches.