Planetary Transfer Gear Set With Direction-Dependent Gear Ratios
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Solution Overview
Problem
Actuation systems, such as screw-nut driven compressive loaded actuators, face inefficiencies due to differing torque and stroke time requirements for extension and retraction strokes, leading to oversizing of the system to accommodate maximum demands.
Innovation Solution
A variable gear ratio gear set system incorporating a planetary gear set with one-way clutches that change gear ratios based on the direction of input shaft rotation, allowing for optimized gear ratios for both extension and retraction strokes by altering torque transmission paths through the sun gear, carrier, and ring gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the actuator and gear set are sized for maximum torque and stroke time requirements, then the system can handle both extension and retraction strokes, but the system becomes oversized with increased weight and material usage
Solution Approach 1:
The patent applies dynamics by implementing a variable gear ratio system that changes based on the direction of actuator movement. The planetary gear set with one-way clutches automatically switches between a first gear ratio for extension strokes and a second gear ratio for retraction strokes, allowing the system to adapt its mechanical advantage dynamically rather than being fixed at a conservative oversized design
Solution Approach 2:
The patent changes the gear ratio parameter based on operational conditions. By using one-way clutches to engage different gear paths in the planetary gear set depending on rotation direction, the system transitions between two distinct gear ratios, optimizing the torque-speed characteristics for each stroke type without requiring an oversized design that accommodates both extremes simultaneously
2Device complexity
If a single gear ratio is used for both extension and retraction strokes, then the system structure is simpler, but the system cannot be optimized for the different torque and stroke time requirements of each direction
Solution Approach 1:
The system dynamically switches between two gear ratios using direction-sensitive one-way clutches in the planetary gear set. This allows optimization of stroke time for both extension and retraction operations while maintaining a relatively compact single-gear-set structure rather than requiring separate gear sets for each direction
Solution Approach 2:
The planetary gear set serves multiple functions by incorporating one-way clutches that enable it to operate in two distinct gear ratio modes within a single unified structure. This multi-functional design achieves directional optimization without duplicating the entire gear set, balancing complexity and performance
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 solution enables the actuation system to be sized more efficiently, reducing weight and size by allowing separate optimization of gear ratios for each stroke, thereby improving performance and reducing material usage.
Implementation Method 1
A plurality of one-way clutches are positioned in the gear set and are engageable such that the system has a first gear ratio when the input shaft is rotated in a first direction, and a second gear ratio when the input shaft is rotated in a second direction
Data Source
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AI summary
A variable gear ratio gear set system includes a planetary gear set (24) including a sun gear (28) locate at a central axis of rotation, a plurality of planet gears (32) meshed with the sun gear and retained at a carrier (34), and a ring gear (38) surrounding the plurality of planet gears and meshed therewith. An input shaft (22) inputs rotational energy to the planetary gear set at a first rotational speed, and an output shaft (26) outputs rotational energy from the planetary gear set at a second rotational speed. A plurality of one-way clutches (40a, 40b, 40c, 40d) are positioned in the gear set and are engageable such that the system has a first gear ratio when the input shaft is rotated in a first direction, and a second gear ratio when the input shaft is rotated in a second direction.