Four-Planetary Transmission Layout for 10-Speed Ratio Coverage
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Solution Overview
Problem
Current multiple speed transmissions face challenges in achieving a high number of speed ratios with improved performance, cost efficiency, responsiveness, and packaging constraints, particularly in military tracked vehicles requiring high ratio coverage and low transmission losses.
Innovation Solution
The design incorporates multiple planetary gearsets and torque-transmitting mechanisms that are selectively engageable in combinations to establish at least ten forward and one reverse speed ratio, allowing for adaptable packaging on single or parallel axes, utilizing a combination of planetary gearsets and torque-transmitting mechanisms to achieve a wide range of speed ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gearsets and torque-transmitting mechanisms are used to achieve high number of speed ratios, then the speed ratio coverage is improved, but the device complexity increases
Solution Approach 1:
The transmission system is divided into multiple planetary gearsets (first, second, third, and fourth planetary gearsets) with distinct functions. Each gearset handles specific speed ratio ranges, allowing the system to achieve high overall speed ratio coverage (at least 10 forward ratios) while managing complexity through modular functional segmentation
Solution Approach 2:
Multiple planetary gearsets are interconnected through a nested architecture where gearsets are coupled in sequence through interconnecting members and torque-transmitting mechanisms. The first planetary gearset connects to the second, which connects to the third, and so on, creating a compact nested structure that achieves high speed ratio coverage without proportionally increasing overall system complexity
2Force
If friction clutches and brakes are used to achieve multiple speed ratios, then the transmission can provide maximum tractive effort at lower speeds, but transmission losses increase at top operating speeds
Solution Approach 1:
The transmission system dynamically engages and disengages different torque-transmitting mechanisms based on operating conditions. At lower speeds, friction clutches and brakes are engaged to provide maximum tractive effort through mechanical locking. At higher operating speeds, the system transitions to different mechanisms that minimize friction losses, optimizing performance across the entire operating range
Solution Approach 2:
The transmission changes its mechanical configuration parameters by selectively engaging different torque-transmitting mechanisms. For low-speed high-torque operations, the system engages friction-based locking mechanisms. For high-speed operations, it transitions to gear-based torque transmission with lower losses, effectively changing the operational parameters to match driving conditions
3Speed
If more torque-transmitting mechanisms are added to establish more speed ratios, then the responsiveness is improved, but the cost increases
Solution Approach 1:
Each torque-transmitting mechanism is designed with multi-functionality to perform multiple roles. The mechanisms can engage different planetary gearsets and provide multiple speed ratios through selective engagement. This universality allows the transmission to achieve high responsiveness with fewer mechanisms, as each mechanism can handle multiple operational states rather than requiring dedicated mechanisms for each speed ratio
Data Source
AI summary
A multiple speed transmission includes an input member, an output member, first, second, third and fourth planetary gearsets each having first, second and third members, and a plurality of interconnecting members each connected between at least one of the first, second, third, and fourth planetary gearsets and at least another of the first, second, third, and fourth planetary gearsets. The transmission includes a plurality of torque-transmitting mechanisms between the input and output members, wherein the torque transmitting mechanisms are selectively engageable in combinations of at least four to establish at least ten forward speed ratios between the input member and the output member.