External Rotor Trimmer Drive With Low-Ratio Gearing and Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electric trimmers face challenges with heat dissipation, leading to high energy consumption and reduced usage time, and there is a lack of specific research on external rotor motors and their heat dissipation structures for improved performance.
Innovation Solution
A trimmer design featuring an external rotor motor with a diameter of 50 mm or greater, a power transmission assembly with a pinion and big gear having a transmission ratio less than 6, and a heat dissipation system including a fan and heat dissipation fins to manage heat effectively, while also incorporating a metal top cover for waterproof and dust-proof protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a traditional motor with high speed and high transmission ratio is used, then the cutting power is sufficient, but the heat generated is considerable and energy consumption increases
Solution Approach 1:
The patent inverts the traditional motor configuration by using an external rotor motor instead of an internal rotor motor. This inversion allows the rotor to be positioned outside the stator, creating a larger diameter rotor (≥50mm) that generates higher torque at lower speeds, thereby reducing heat generation and energy consumption while maintaining sufficient cutting power.
Solution Approach 2:
The patent changes key parameters of the motor system: rotor diameter is increased to 50mm or greater, transmission ratio is reduced to less than 6, and operating speed is lowered. These parameter changes enable the motor to operate in a more efficient range with lower heat generation while maintaining the required cutting power through the increased rotor diameter and optimized gear ratio.
2Temperature
If a motor with large diameter and low transmission ratio is used, then heat generation is reduced and energy efficiency is improved, but the device complexity increases due to external rotor configuration
Solution Approach 1:
The patent segments the motor into distinct components: the external rotor, stator, housing assembly, and power transmission assembly. This segmentation allows for optimized design of each component, particularly enabling the large diameter rotor to be positioned externally while maintaining a compact overall structure through separate housing assemblies for the motor and gear mechanism.
3Use of energy by moving object
If an external rotor motor is used with optimized transmission ratio, then energy efficiency is improved, but the heat dissipation structure becomes more complex
Solution Approach 1:
The patent merges the heat dissipation function with existing structural components. The housing assembly serves dual purposes: it encloses the power transmission components and simultaneously acts as a heat dissipation structure with integrated channels and fins. This merging eliminates the need for separate heat dissipation components, reducing overall structural complexity while maintaining effective heat management.
4Power
If the motor diameter is increased to 50mm or greater, then torque and energy efficiency are improved, but the overall device size increases
Solution Approach 1:
The patent transitions from a compact internal rotor configuration to an external rotor configuration, utilizing the radial dimension more effectively. By positioning the rotor externally and using a larger diameter (≥50mm), the system generates higher torque without proportionally increasing the overall device volume, as the rotor is integrated into the existing housing structure rather than requiring additional space.
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
The design results in reduced heat generation, lower current consumption, improved energy efficiency, and extended motor life, allowing the trimmer to operate effectively in wet conditions without performance degradation.
Implementation Method 1
a fan sandwiched between the bottom cover and the housing assembly, wherein the bottom cover defines a blower chamber for receiving the fan and a heat dissipation channel extending therethrough for air passing from the blower chamber to outside
Implementation Method 2
the bottom cover also includes at least two heat dissipation fins extending along a longitudinal direction thereof, and wherein each heat dissipation passage is formed between two adjacent heat dissipation fins
Implementation Method 3
the motor is an external rotor motor which has a diameter greater or equal to 50 mm
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present disclosure provides a trimmer (100), the trimmer (100) comprises a handle assembly (10), a power mechanism (20) installed at one end of the handle assembly (10), and a blade assembly (30) connected to the power mechanism (20). The power mechanism (20) has a housing assembly (21), a motor (22; 70) received in the housing assembly (21), and a power transmission assembly (23) mounted on the housing assembly (21). The motor (22; 70) is an external rotor motor (22; 70) with a diameter greater than or equal to 50 mm. The power transmission assembly (23) has pinion (232; 90) coaxially sleeved on an output shaft of the motor (22; 70) and a big gear (233; 80) meshing with the pinion (232; 90), and a transmission ratio of the pinion (232; 90) to the big gear (233) is less than 6. By such arrangement, the trimmer (100) can obtain the best output effect under a condition that the output power of the motor (22; 70) is unchanged.