Nine-Speed Transmission Using Nested Planetary Gears
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Solution Overview
Problem
Current multiple speed transmissions face challenges in achieving improved efficiency, responsiveness, smoothness, reduced size, and weight, while maintaining cost-effectiveness, particularly in achieving a compact design with a sufficient number of gear ratios.
Innovation Solution
A transmission design incorporating four planetary gear sets and seven torque transmitting devices, including a selectable one-way clutch, to establish a plurality of forward and reverse speed ratios through selective engagement of interconnecting members and torque transmitting devices, allowing for a compact and efficient nine-speed transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional multiple speed transmission uses a combination of friction clutches, planetary gear arrangements and fixed interconnections to achieve a plurality of gear ratios, then the transmission can provide multiple speed ratios, but the size and weight of the transmission increase
Solution Approach 1:
The patent employs nested planetary gear sets where smaller planetary gear sets are positioned within or alongside larger ones, allowing multiple gear ratios to be achieved within a compact structure. The first, second, third and fourth planetary gear sets are arranged to share common components and space, reducing overall transmission size while maintaining nine forward and reverse gear ratios.
Solution Approach 2:
The patent merges multiple planetary gear sets with shared components, where interconnecting members connect different planetary gear sets and torque transmitting devices are selectively engaged across multiple gear sets. This consolidation achieves multiple speed ratios with fewer discrete components, reducing weight compared to conventional separate gear train designs.
2Adaptability or versatility
If the number and physical arrangement of the planetary gear sets are increased to achieve desired speed ratios, then the transmission can provide more gear ratios, but the packaging space required increases
Solution Approach 1:
The planetary gear sets are arranged in a nested configuration where gear sets share common mounting spaces and interconnecting members. The first, second, third and fourth planetary gear sets are positioned to maximize space utilization, with components overlapping in the radial and axial directions to minimize the transmission's external dimensions while accommodating nine forward and reverse ratios.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement of planetary gear sets, arranging them along multiple axes rather than simple linear sequences. Interconnecting members connect gear sets in complex spatial patterns, allowing compact packaging by exploiting volume rather than just linear space, achieving high gear ratio count in a small footprint.
3Adaptability or versatility
If conventional friction clutches and brakes are used as torque transmitting devices, then the transmission can achieve multiple speed ratios, but the responsiveness and smoothness are limited
Solution Approach 1:
The patent incorporates a selectable one-way clutch that can dynamically change its engagement state based on operating conditions, providing different torque transmission characteristics. This selectable mechanism allows the transmission to switch between friction-based and rigid torque transmission modes, improving responsiveness during gear changes and smoothness during operation compared to conventional fixed friction clutch designs.
Solution Approach 2:
The transmission system changes the physical state or engagement parameter of torque transmitting devices, particularly the selectable one-way clutch, which can transition between engaged and disengaged states. This parameter change enables more precise control over torque flow paths through the planetary gear sets, enhancing shift responsiveness and operational smoothness while maintaining multiple speed ratios.
Data Source
AI summary
A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. The torque transmitting devices include clutches and brakes including a selectable one-way clutch actuatable in combinations of two to establish a plurality of forward gear ratios and one reverse gear ratio.