Multi-speed Transmission with 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
A transmission design incorporating four planetary gear sets and multiple torque transmitting devices, including clutches and brakes, with specific interconnections between the gear sets to achieve ten 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 more planetary gear sets are added to achieve more gear ratios, then the number of speeds increases, 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 where multiple planetary gear sets share common components such as the input member, output member, and stationary member. This merging approach allows the transmission to achieve ten forward and one reverse gear ratio while avoiding the weight penalty of separate gear sets, as the shared components reduce overall material requirements and assembly mass.
2Adaptability or versatility
If more planetary gear sets are added to achieve more gear ratios, then the number of speeds increases, 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 interconnected through shared members. The first, second, third, and fourth planetary gear sets are arranged such that their sun gears, ring gears, and carrier members are continuously connected or selectively interconnected, creating a compact nested structure that maximizes gear ratio diversity within minimal volumetric space.
3Ease of operation
If complex interconnections are added to achieve smooth shifting, then responsiveness and smoothness improve, but device complexity increases
Solution Approach 1:
The patent incorporates continuous connections between carrier members and sun gears of adjacent planetary gear sets, establishing pre-configured mechanical pathways that enable smooth transitions between gear ratios. These continuous interconnections are built into the transmission architecture beforehand, allowing torque to flow seamlessly through the system during shifting operations without requiring complex real-time control mechanisms.
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 three to establish a plurality of forward gear ratios and at least one reverse gear ratio.