Multi-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 design with a high number of gear ratios.
Innovation Solution
The transmission employs four planetary gear sets and a plurality of torque transmitting devices, including clutches and brakes, with specific interconnections between the gear sets to achieve eleven or more speeds, allowing for selective engagement of torque transmitting mechanisms to establish various forward and reverse gear ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of planetary gear sets is increased to achieve more gear ratios, then the number of gear ratios is improved, but the size and weight of the transmission increase
Solution Approach 1:
The patent combines multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission assembly where gear sets share common components such as carriers and rings. This merging approach allows achieving 11 or more gear ratios without proportionally increasing weight, as components are reused across multiple gear ratio configurations.
Solution Approach 2:
The planetary gear sets are designed with universal components that serve multiple functions. For example, the carrier member of the second planetary gear set is continuously connected to the input member, while the carrier member of the fourth planetary gear set is continuously connected to the output member, allowing these components to participate in multiple gear ratio configurations simultaneously.
2Adaptability or versatility
If the number of planetary gear sets is increased to achieve more gear ratios, then the number of gear ratios is improved, but the physical size of the transmission increases
Solution Approach 1:
The patent employs a nested arrangement where planetary gear sets are positioned concentrically and share common rotational members. The first, second, third, and fourth planetary gear sets are arranged to share carriers and rings, creating a compact nested structure that achieves high gear ratios without proportionally increasing transmission volume.
Solution Approach 2:
The patent utilizes multi-dimensional spatial arrangement of planetary gear sets, with components positioned in different radial and axial dimensions. The interconnecting members and torque transmitting devices are arranged in three-dimensional space to achieve compact packaging of multiple gear sets.
3Adaptability or versatility
If more torque transmitting devices are added to control more planetary gear sets, then the number of gear ratios is improved, but the device complexity increases
Solution Approach 1:
The patent segments the control function by assigning specific torque transmitting devices to control specific planetary gear sets. For example, a first torque transmitting device controls the first planetary gear set, a second torque transmitting device controls the second planetary gear set, and so on. This segmentation simplifies the control logic for each device while achieving complex overall gear ratio configurations.
Solution Approach 2:
The patent employs dynamic control where torque transmitting devices are selectively engaged and disengaged to achieve different gear ratios. The continuous connections (input member to second planetary gear set carrier, output member to fourth planetary gear set carrier) provide stable mechanical pathways, while selective torque transmission adds dynamic flexibility without excessive complexity.
Data Source
AI summary
A transmission has an input member, an output member, at least 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 actuatable in combinations of four or more to establish a plurality of forward gear ratios and at least one reverse gear ratio.