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.
Innovation Solution
A transmission design incorporating four planetary gear sets and various torque transmitting devices, including clutches and brakes, with permanent and selective interconnections between gear sets to achieve multiple forward and reverse speed ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional planetary gear arrangements are used to achieve multiple speed ratios, then the transmission can provide the required gear 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 system where multiple planetary gear sets share common components such as carriers, rings, and sun gears. This merging approach allows the transmission to achieve multiple speed ratios while reducing overall size and weight compared to using separate planetary gear sets for each ratio.
Solution Approach 2:
The planetary gear sets are designed with universal components that serve multiple functions. For example, the carrier members and ring gears are shared across different planetary gear sets and are continuously connected to provide both structural support and torque transmission pathways for multiple speed ratios, reducing the need for additional dedicated components.
2Productivity
If more planetary gear sets are added to improve efficiency and responsiveness, then the transmission performance improves, but the packaging space required increases
Solution Approach 1:
The patent employs a nested arrangement where planetary gear sets are integrated within a compact configuration. The planetary gears are positioned within the carriers, which are themselves integrated with ring gears and sun gears in a nested manner, allowing multiple gear sets to occupy minimal space while maintaining efficient torque transmission pathways.
Solution Approach 2:
The transmission utilizes three-dimensional spatial arrangement to pack four planetary gear sets into a compact volume. Components are arranged in multiple dimensions with continuous connections between carriers, rings, and sun gears that optimize space utilization while maintaining efficient torque transmission for improved productivity.
3Ease of operation
If complex interconnections between planetary gear sets are implemented to achieve smooth shifting, then the responsiveness improves, but the device complexity increases
Solution Approach 1:
The patent incorporates continuous connections between carriers, rings, and sun gears that are pre-configured to facilitate smooth transitions between speed ratios. These continuous interconnections are established beforehand through the mechanical design, allowing torque to be smoothly transmitted during shifting operations without requiring complex control mechanisms during the actual shifting process.
4Manufacturing precision
If multiple torque transmitting devices are used to achieve precise gear ratio control, then the speed ratio precision improves, but the manufacturing cost increases
Solution Approach 1:
The patent achieves precise gear ratio control by varying the parameters of the planetary gear sets, such as the number of teeth on sun gears, ring gears, and planet gears. By changing these geometric parameters across the four planetary gear sets, the transmission can provide multiple precise speed ratios while using standard manufacturing processes for the gear components, avoiding the need for complex or expensive specialized manufacturing techniques.
Data Source
AI summary
A transmission is provided having 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 a brake actuatable in combinations of four to establish a plurality of forward gear ratios and at least one reverse gear ratio.