Power Tool Planetary Transmission for Multi-Range Speed and Torque
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Solution Overview
Problem
Existing power tools lack a transmission arrangement that can produce a wide range of output speeds and torques, limiting their versatility for tasks such as drilling large diameter holes, installing drywall screws, and high-speed drilling operations, often requiring separate tools for standard and heavy-duty applications due to energy consumption issues with early cordless rotary power tools.
Innovation Solution
A multi-speed compound planetary transmission system with a gearset portion that includes an input sun gear, compound planet gears, and ring gears, allowing for selective operation in different gear reduction ratios to provide a wide range of speed and torque outputs, optimized for low-speed, high-torque operations with modern high-capacity batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-speed or dual-speed transmission is used, then the device complexity is reduced, but the adaptability for diverse operations is insufficient
Solution Approach 1:
The transmission system employs a movable member that can be positioned in different switch positions to dynamically change the operational mode of the first gearset portion. This allows the transmission to adapt between multiple gear reduction ratios (first, second, third, and fourth modes) by selectively engaging different ring gears with the movable member, thereby providing versatility for diverse operations without requiring multiple separate transmission systems
Solution Approach 2:
The first gearset portion is designed to operate in multiple modes (first, second, third, and fourth gear reduction ratios) through the selective engagement of different ring gears. This multi-functional design allows a single transmission system to perform diverse operations including high-speed drilling, standard drilling, and low-speed high-torque operations, eliminating the need for multiple specialized tools
2Force
If a low-speed, high-torque transmission is configured, then the torque output is improved, but the high-speed performance is impaired
Solution Approach 1:
The transmission system dynamically switches between different gear reduction ratios based on operational needs. The movable member can position the first gearset portion in a fourth mode for low-speed, high-torque operations (improving torque output) or in a first mode for high-speed operations (restoring high-speed performance). This dynamic reconfiguration allows the system to optimize for either torque or speed depending on the task requirements
Solution Approach 2:
The system changes the gear reduction ratio parameter by selectively engaging different ring gears with the movable member. By adjusting this parameter between multiple discrete values (first, second, third, and fourth gear reduction ratios), the transmission can optimize the balance between speed and torque output to match different operational requirements, resolving the trade-off between high-speed performance and low-speed torque capability
3Adaptability or versatility
If multiple separate tools are purchased for different applications, then the adaptability for diverse operations is improved, but the device complexity and cost increase
Solution Approach 1:
The transmission system is designed with multi-functionality to replace multiple separate tools. By incorporating a first gearset portion that can operate in four different modes (first, second, third, and fourth gear reduction ratios) and a second gearset portion with additional reduction capabilities, the single power tool can perform diverse operations including high-speed drilling, standard drilling, and low-speed high-torque operations, eliminating the need for consumers to purchase separate medium-duty and heavy-duty tools
4Device complexity
If early cordless rotary power tools with single-speed transmissions are used, then the device complexity is reduced, but the energy consumption is excessive for low-speed operations
Solution Approach 1:
The transmission system dynamically adjusts the gear reduction ratio based on operational requirements. When low-speed, high-torque operations are needed, the movable member positions the first gearset portion in the fourth mode, providing appropriate mechanical advantage that reduces energy consumption by matching the motor's optimal operating range to the load requirements, rather than forcing the motor to operate inefficiently at high speeds
Solution Approach 2:
The system changes the gear reduction ratio parameter to optimize energy efficiency. By selecting from multiple gear reduction ratios (first, second, third, and fourth modes) in the first gearset portion and combining with the second gearset portion, the transmission can match the motor's output characteristics to the load requirements, thereby reducing excessive energy consumption during low-speed operations while maintaining simplicity through a integrated transmission design
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
Enables a power tool to perform diverse operations with improved efficiency and reduced need for multiple tools by providing a wide range of speed and torque outputs, effectively addressing the limitations of previous transmission systems and energy consumption issues.
Implementation Method 1
The planetary stage includes an input sun gear, a movable member, a compound planet gear having a first planet gear and a second planet gear coupled together for common rotation, an output planet carrier, and at least one ring gear
Data Source
AI summary
A tool having a housing assembly, which defines a handle, a motor assembly, a trigger assembly, a spindle and a transmission assembly. The motor assembly is received in the housing assembly and has an output shaft. The trigger assembly is coupled to the housing assembly and is configured for use in actuating the motor assembly. The transmission assembly transmits rotary power between the output shaft of the motor assembly and the spindle. The transmission assembly includes a planetary stage with an input sun gear, an output planet carrier and a compound planet gear having a first planet gear and a second planet gear coupled together for common rotation on the output planet carrier. The planetary stage is selectively operable in a first gear reduction and a second, relatively lower gear reduction in which the compound planet gear cooperates to produce at least one intermediate gear reduction within the planetary stage.