Multi-Speed Transmission Nested Planetary Gear Low Range
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Solution Overview
Problem
Current multiple speed transmissions face challenges in achieving improved efficiency, responsiveness, smoothness, reduced size, and weight, particularly in providing a selectable low range function without the need for additional speed reducing gear sets in transfer cases.
Innovation Solution
A multi-speed transmission design incorporating two planetary gear sets that are stackable, a selectively speed reducing gear set, and multiple torque transmitting devices such as clutches and brakes, allowing for the establishment of a plurality of forward and reverse speed ratios through various interconnections and engagements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a transfer case with a speed reducing gear set is used to provide low range capability, then the transmission can achieve low speed ratio and high torque capability, but the size and weight of the transmission system increases
Solution Approach 1:
The patent combines the speed reducing gear set functionality directly into the transmission assembly by integrating a planetary gear set that can operate in both direct drive and reduced speed modes. This merging eliminates the need for a separate transfer case with additional speed reducing gears, thereby reducing overall system weight while maintaining the ability to provide high torque capability in low range applications
Solution Approach 2:
The planetary gear set is designed to serve multiple functions: it can operate as a direct drive connection during normal operation and as a speed reducing gear set when low range capability is required. This multi-functionality allows the transmission to provide both high speed and low speed/torque capabilities without requiring separate dedicated components for each function, thus reducing overall system weight
2Adaptability or versatility
If a transfer case with additional speed reducing gear set is used, then low range capability is achieved, but the packaging space and complexity of the transmission system increases
Solution Approach 1:
The patent merges the low range capability functionality into the existing transmission planetary gear set rather than adding a separate speed reducing gear set in the transfer case. By combining these functions into a single integrated planetary gear arrangement, the system achieves low range capability while reducing the number of separate components and interconnections required, thereby simplifying the overall system
Solution Approach 2:
The planetary gear set is configured with nested components where the same gear elements serve multiple purposes across different operating ranges. The planetary gears, carrier, and ring gear are arranged to provide both direct drive and reduced speed ratios through selective engagement, creating a compact nested structure that eliminates the need for additional external speed reducing components
3Productivity
If multiple planetary gear sets are used to achieve multiple speed ratios, then the desired speed ratios are obtained, but the size and packaging space of the transmission increases
Solution Approach 1:
The patent employs a nested planetary gear configuration where multiple planetary gear sets are arranged concentrically with shared components. The inner planetary gear set and outer planetary gear set share common elements such as the ring gear or carrier, allowing multiple speed ratios to be achieved within a compact radial arrangement rather than requiring sequential axial stacking, thus reducing overall transmission packaging space
Solution Approach 2:
The patent merges multiple planetary gear sets into a single integrated assembly where components are shared between different gear stages. By combining multiple gear sets that would traditionally require separate housings and mounting spaces into one unified structure with common members, the transmission achieves multiple speed ratios while minimizing the total packaging footprint
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables a compact, cost-effective transmission with a selectable low range function, eliminating the need for additional speed reducing gear sets in transfer cases, while achieving efficient torque transmission and multiple speed ratios.
Implementation Method 1
two planetary gear sets one of which is a selectively speed reducing gear set, another two planetary gear sets that are stackable
Data Source
AI summary
A transmission is provided having an input member, an output member, two planetary gear sets one of which is a selectively speed reducing gear set, another two planetary gear sets that may be stacked or nested to form a planetary gear set assembly, 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 stacked or nested planetary gear set assembly has a carrier member for rotatably supporting a first plurality of pinion gears and a second plurality of pinion gears, a ring gear and a common gear member. The torque transmitting devices include clutches and brakes.