Planetary Transmission Coupler Layout for Nine Forward Speeds
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Solution Overview
Problem
Current multi-speed transmissions face challenges in achieving a sufficient number of forward and reverse speed ratios using existing configurations of planetary gearsets and selective couplers, which limits their versatility and efficiency.
Innovation Solution
The proposed solution involves a multi-speed transmission design that incorporates a combination of planetary gearsets and selective couplers, including clutches and brakes, to achieve at least nine forward speed ratios and one reverse speed ratio, with specific configurations of gearsets and couplers allowing for varied interconnections to optimize gear ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing configurations of planetary gearsets and selective couplers are used, then the transmission structure is simpler, but the number of forward and reverse speed ratios is insufficient
Solution Approach 1:
The transmission system is divided into four separate planetary gearsets (first, second, third, and fourth planetary gearsets), each capable of independently providing different speed ratios. This segmentation allows the system to achieve a greater total number of speed ratios (at least nine forward and one reverse) by combining the capabilities of individual gearsets, rather than relying on a single complex gearset configuration.
Solution Approach 2:
The planetary gearsets are arranged in a nested or cascaded configuration where the output of one planetary gearset feeds into the input of the next. This nesting approach allows multiple gear reduction stages to be combined in a compact arrangement, multiplying the number of achievable speed ratios while maintaining a relatively compact overall structure.
2Adaptability or versatility
If more planetary gearsets and selective couplers are added to increase speed ratios, then the versatility improves, but the device complexity increases
Solution Approach 1:
Each planetary gearset is designed with multiple components (sun gear, planet gears, ring gear, and carrier) that can serve multiple functions. The selective couplers can engage different components to achieve various speed ratios, allowing each gearset to provide multiple speed ratio options rather than a single fixed ratio. This multi-functionality reduces the need for additional dedicated gearsets for each speed ratio.
Solution Approach 2:
The transmission system employs dynamic engagement and disengagement of selective couplers to change speed ratios on-the-fly. Rather than requiring physical reconfiguration or multiple fixed-ratio gearsets, the system dynamically selects different component combinations within the planetary gearsets to achieve the desired speed ratio, reducing mechanical complexity while maintaining versatility.
Data Source
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AI summary
A multi-speed transmission (100, 300, 500, 700) including a plurality of planetary gearsets (108, 110, 112, 114, 308, 310, 312, 314, 508, 512, 514, 708, 712) and a plurality of selective couplers (162, 164, 166, 168, 170, 172, 362, 364, 366, 368, 370, 372, 562, 564, 566, 568, 570, 572, 762, 764, 766, 768, 770, 772) to achieve at least nine forward speed ratios is disclosed. The plurality of planetary gearsets (108, 110, 112, 114, 308, 310, 312, 314, 508, 512, 514, 708, 712) may include a first planetary gearset (108, 308, 508, 708), a second planetary gearset (110, 310), a third planetary gearset (112, 312, 512, 712), and a fourth planetary gearset (114, 314, 514). The plurality of selective couplers (162, 164, 166, 168, 170, 172, 362, 364, 366, 368, 370, 372, 562, 564, 566, 568, 570, 572, 762, 764, 766, 768, 770, 772) may include a number of clutches (164, 166, 364, 366, 564, 566, 764, 766) and a number of brakes (162, 168, 170, 172, 362, 368, 370, 372, 562, 568, 570, 572, 762, 768, 770, 772). The multi-speed transmission (100, 300, 500, 700) may have four planetary gearsets (108, 110, 112, 114, 308, 310, 312, 314) and six selective couplers (162, 164, 166, 168, 170, 172, 362, 364, 366, 368, 370, 372, 562, 564, 566, 568, 570, 572, 762, 764, 766, 768, 770, 772). The six selective couplers (162, 164, 166, 168, 170, 172, 362, 364, 366, 368, 370, 372, 562, 564, 566, 568, 570, 572, 762, 764, 766, 768, 770, 772) may include two clutches (164, 166, 364, 366, 564, 566, 764, 766) and four brakes (162, 168, 170, 172, 362, 368, 370, 372, 562, 568, 570, 572, 762, 768, 770, 772). The four planetary gearsets (108, 110, 112, 114, 308, 310, 312, 314) may include three minus planetary gearsets (108, 112, 114) and one plus planetary gearset (110) or two minus planetary gearsets (308, 312) and two plus planetary gearsets (310, 314). The multi-speed transmission (100, 300, 500, 700) may include at least one Ravigneaux gearset (508, 708, 712).