Pinion-Fan Power Tool Assembly for Cooling and Torque Transfer
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Solution Overview
Problem
Existing power tools face challenges in efficiently transferring torque from the motor to the transmission while effectively cooling the motor, particularly in designs where fans are coupled to the output shaft, leading to inefficiencies and potential interference.
Innovation Solution
A power tool design featuring a pinion with a bushing portion and toothed portion, integrated with a fan, and a bearing system that supports the pinion and output shaft, allowing for seamless torque transfer and cooling airflow, utilizing a planetary transmission with a sun gear configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a fan is integrated with the pinion and bearing system for motor cooling, then cooling efficiency is improved, but torque transfer efficiency deteriorates due to compromised mechanical connection
Solution Approach 1:
The pinion is divided into functionally distinct segments: a bushing portion for fan attachment, a cylindrical portion for bearing support, and a toothed portion for torque transfer. This segmentation allows each portion to be optimized for its specific function, enabling the fan to be coupled to the bushing portion without compromising the torque transfer capability of the toothed portion.
Solution Approach 2:
The fan cooling function is extracted as a separate component that couples to the pinion's bushing portion rather than being integrated into the torque transfer path. This allows the fan to be removed or replaced independently without affecting the pinion's mechanical integrity or torque transfer efficiency.
2Loss of energy
If a robust bearing system is added to support the pinion and output shaft, then torque transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The bearing system is merged with the pinion assembly, where the bearing directly supports the pinion's cylindrical portion which is itself coupled to the output shaft. This integrated approach provides robust support for both components while minimizing the number of separate parts and assembly steps.
3Device complexity
If the pinion is integrally formed with the output shaft for simplified structure, then device complexity is reduced, but adaptability deteriorates for different fan and bearing configurations
Solution Approach 1:
The pinion is segmented into distinct portions (bushing, cylindrical, and toothed portions) that can be manufactured separately and assembled in different configurations. This allows the same pinion structure to accommodate various fan types and bearing arrangements while maintaining overall structural simplicity.
Solution Approach 2:
The pinion's bushing portion is designed with universal coupling features (such as splines or mounting holes) that can interface with different fan configurations, while the cylindrical portion provides a standard bearing interface. This multi-functional design enables the same pinion to work with various fans and bearings without requiring custom integral designs.
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
Enhances torque transfer efficiency and cooling effectiveness by integrating a fan with the pinion, reducing interference and improving overall performance of the power tool.
Implementation Method 1
a bearing with an inner and outer race and rollers between the inner and outer races arranged on the cylindrical portion for supporting the pinion and the output shaft
Implementation Method 2
a fan coupled to the bushing portion for cooling the motor as the output shaft rotates
Data Source
Figure 1~2
Figure 2A~3
Figure 4
AI summary
A power tool (10) includes an electric motor (18) having an output shaft (34), a transmission (22) having a transmission housing (70), a spindle (24) rotatable in response to receiving torque from the transmission (22) and a pinion (42) coupled to the output shaft (34). The pinion (42) includes a bushing portion (46), a toothed portion (50) for driving the transmission (22), and a cylindrical portion (54) between the bushing portion (46) and the toothed portion (50). The power tool (10) further comprises a fan (58) coupled to the bushing portion (46) of the pinion (42) and a bearing (82) arranged between the cylindrical portion (54) and the transmission housing (70) for rotatably supporting the pinion (42) and the output shaft (34).