Ten-Speed Transmission Using Nested Planetary Gear Sets
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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 ten-speed configuration.
Innovation Solution
A transmission design utilizing four planetary gear sets and a plurality of torque transmitting devices, including clutches and brakes, to establish at least ten forward and one reverse speed ratio through selective interconnections between the planetary gear sets and a stationary member, optimizing gear ratios and packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a 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 combines four planetary gear sets into a single integrated transmission assembly with shared components. Multiple planetary gear sets are merged through common mounting structures, shared torque transmitting devices, and interconnected gear members, allowing the transmission to achieve ten forward speed ratios and reverse capability while reducing overall size and weight compared to separate gear train arrangements
Solution Approach 2:
The torque transmitting devices (clutches and brakes) are designed to perform multiple functions across different planetary gear sets. Each torque transmitting device can selectively engage different members of different planetary gear sets, enabling a single device to control multiple gear ratios and operational modes, thereby reducing the total number of components needed
2Adaptability or versatility
If the number and physical arrangement of the planetary gear sets are increased to achieve desired speed ratios, then the gear ratio range improves, but the packaging space and cost increase
Solution Approach 1:
The patent employs a nested arrangement where planetary gear sets are positioned concentrically and interlocked. The planetary gears of different sets share common axes and mounting structures, with gear members of one planetary set positioned within or adjacent to members of other sets. This nesting allows multiple gear ratios to be achieved within a compact radial and axial envelope
Solution Approach 2:
The transmission is divided into four distinct planetary gear sets, each capable of providing specific gear ratios. By segmenting the overall gear ratio achievement into multiple smaller planetary sets working in combination, the design achieves a wide speed ratio range (ten forward ratios) while maintaining compact packaging, as each segment contributes specific ratios rather than requiring one large complex gear train
3Adaptability or versatility
If six torque transmitting mechanisms are used to establish at least ten forward speed ratios and at least one reverse speed ratio, then the gear ratio versatility improves, but the device complexity increases
Solution Approach 1:
Each of the six torque transmitting mechanisms (two brakes and four clutches) is designed to control multiple members across different planetary gear sets. For example, a single clutch can simultaneously engage members from two different planetary sets, and brakes can lock multiple members to the housing. This multi-functionality allows ten forward speed ratios and reverse capability to be achieved with only six controlling mechanisms, reducing complexity compared to having one mechanism per gear ratio
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. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches and brakes.