Multiple Speed Transmission Planetary Gear Configuration
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Solution Overview
Problem
Conventional automatic transmissions struggle to efficiently manage a wide range of vehicle speeds, as many engines operate optimally within a narrow speed range, requiring transmissions that can adapt power transmission speed ratios effectively for both low-speed acceleration and high-speed cruising.
Innovation Solution
The design incorporates a family of transmissions with multiple simple planetary gear sets and strategically placed clutches and brakes, allowing for fixed and selectable speed relationships between input and output shafts, enabling the establishment of various speed ratios through coordinated engagement and release of these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmission uses a fixed gearing arrangement, then the structure is simple, but it cannot adapt to different vehicle speeds and engine operating ranges
Solution Approach 1:
The transmission is divided into multiple planetary gear sets (first, second, third, and fourth planetary gear sets) that can be independently engaged or disengaged. Each gear set provides specific gear ratios, allowing the transmission to offer multiple forward and reverse gear ratios. This segmentation enables the transmission to adapt to different vehicle speeds and engine operating ranges while maintaining a manageable structural complexity through modular design.
2Productivity
If a transmission uses a shiftable gearing arrangement with multiple gear ratios, then it can optimize engine performance across different speeds, but the device complexity increases
Solution Approach 1:
Multiple planetary gear sets are combined in a integrated arrangement where elements from different gear sets are interconnected. For example, the ring gear of the first planetary gear set is connected to the sun gear of the second planetary gear set, and the ring gear of the second planetary gear set is connected to the sun gear of the third planetary gear set. This merging approach allows the transmission to achieve multiple gear ratios through coordinated engagement of clutches and brakes, optimizing engine performance across different speeds while managing complexity through unified structural design.
3Ease of operation
If the transmission uses multiple planetary gear sets with clutches and brakes, then it can provide seamless shifting between gear ratios, but the manufacturing complexity increases
Solution Approach 1:
The planetary gear sets are designed with universal structural characteristics where each gear set contains sun gears, planet gears, planet carriers, and ring gears that perform multiple functions. For instance, the ring gear of one planetary gear set serves as a connection point for the sun gear of the next planetary gear set, and clutches and brakes are strategically placed to control multiple gear ratios simultaneously. This multi-functionality enables seamless shifting between gear ratios while simplifying manufacturing through standardized component design and reduced part variety.
Data Source
AI summary
A family of transmissions produces at least eight forward and one reverse speed ratio by selective engagement of various combinations of three clutches or brakes. Each transmission includes two fixed gearing arrangements that establish fixed speed relationships between an input shaft, and output shaft, and four other elements. Specifically, the input shaft is constrained to rotate at a speed between that of the first and second elements while the output shaft is constrained to rotate at a speed between that of the third and fourth elements. Additional gearing, clutches, and brakes establish specified selective speed relationships among these elements.