Compact Planetary Transmission with Nested Gear Trains
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Solution Overview
Problem
Existing planetary transmissions are often large and cumbersome due to the need for multiple gear trains, clutches, and brakes to achieve a sufficient number of speed ratios, making them unsuitable for compact industrial applications.
Innovation Solution
A compact multi-speed transmission design utilizing four planetary gear trains and six selectively engagable torque-transmitting mechanisms or control elements, including brakes and clutches, to achieve at least seven forward speeds and one reverse speed, with continuous interconnections between gear train members and selective engagements to optimize gear ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gear trains with clutches and brakes are used to achieve sufficient speed ratios, then the number of speed ratios is improved, but the size and complexity of the transmission increases
Solution Approach 1:
The patent combines four planetary gear trains into a single integrated transmission system where gear trains share common components such as carriers, sun gears, and ring gears. This merging approach allows the system to achieve seven forward speeds and two reverse speeds without requiring separate gear trains for each function, thereby reducing overall complexity while maintaining high adaptability
Solution Approach 2:
Individual components within the planetary gear trains serve multiple functions. For example, carriers and ring gears are continuously interconnected across different gear trains, allowing single components to participate in multiple gear ratio configurations. The six torque-transmitting mechanisms are selectively engaged in different combinations to achieve various speed ratios, demonstrating multi-functionality that reduces the need for dedicated components for each speed ratio
2Adaptability or versatility
If multiple planetary gear trains with clutches and brakes are used to achieve sufficient speed ratios, then the number of speed ratios is improved, but the physical size of the transmission increases
Solution Approach 1:
The planetary gear trains are arranged in a nested configuration where gear trains are positioned concentrically around a common input shaft. Carriers and gear members of different planetary stages are interconnected through shared axes and continuous interconnections, allowing compact packaging that minimizes the overall volume while accommodating multiple gear reduction stages necessary for achieving seven forward speeds and two reverse speeds
3Reliability
If fractionated transmissions with two gearboxes in series are used, then the performance criterion is met, but the transmission becomes large and cumbersome
Solution Approach 1:
Instead of using two separate gearboxes in series, the patent merges four planetary gear trains into a single integrated transmission system. The gear trains share common components and are continuously interconnected, creating a unified system that achieves the required performance (seven forward speeds and two reverse speeds) without the size and complexity penalties of fractionated designs
Solution Approach 2:
The patent transitions from a linear series arrangement of gearboxes to a multi-dimensional planetary configuration where gear trains are arranged concentrically around a common input shaft. This spatial reorganization allows multiple gear reduction stages to be packed into a compact volume while maintaining the required speed ratios and torque transmission capabilities
Data Source
AI summary
The transmission includes a housing, input and output shafts, and four planetary gear trains each having at least three members including a ring gear, at least one carrier, and a sun gear. The input and output shafts are is continuously interconnected with gear(s) and/or carrier(s). Links continuously interconnect the carrier(s) and/or gears between gear trains. The six torque-transmitting mechanisms are engagable in combinations of two to establish at least seven forward speed ratios and at least one reverse speed ratio between the input shaft and the output shaft.