Power Tool Motor Cooling via Segmented Housing Vents
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Solution Overview
Problem
In electric power tools with built-in motors, the narrow air gap between the stator and rotor poses a challenge for efficient cooling, as air flow struggles to enter, leading to inadequate heat dissipation and reduced motor output characteristics.
Innovation Solution
The electric power tool incorporates a segmented housing structure with retaining parts to create sealed chambers and vents, allowing a cooling fan to efficiently direct air flow into the narrow air gap between the stator and rotor, enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air cooling is used for the stator coil, then heat dissipation is improved, but the narrow air gap prevents sufficient air flow from entering
Solution Approach 1:
The housing is segmented into multiple chambers (first chamber, second chamber, third chamber) separated by partition walls. This segmentation allows independent air flow paths to be created, enabling cooling air to be directed specifically into the air gap between stator and rotor through dedicated flow passages, thereby overcoming the limitation of the narrow air gap preventing sufficient air flow entry
Solution Approach 2:
A fan is introduced as an intermediary device to actively generate air flow. The fan is positioned in the first chamber and directs air through flow passages into the air gap, providing the necessary force to overcome the narrow gap resistance and enable effective cooling of the stator coil
2Weight of stationary object
If a built-in motor without motor case is used, then size and weight are reduced, but cooling efficiency deteriorates due to extensive internal space
Solution Approach 1:
The housing interior is divided into multiple functional chambers using partition walls. The first chamber houses the fan, the second chamber contains the motor, and the third chamber provides additional cooling pathways. This segmentation creates organized air flow paths that efficiently cool the motor despite the large internal space, maintaining cooling effectiveness while preserving the weight benefits of the built-in motor design
Solution Approach 2:
Partition walls are strategically positioned to create three-dimensional air flow paths. The flow passages extend through multiple chambers and directions, utilizing the extensive internal space in a structured manner to guide cooling air effectively across the motor components, transforming the challenge of large internal volume into an advantage for comprehensive cooling coverage
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 configuration ensures effective cooling of the stator coil by directing air flow into the air gap, improving motor performance and reducing heat-related issues.
Implementation Method 1
a cooling fan coupled to the first motor shaft is housed in the first chamber
Data Source
Figure 1
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AI summary
A first retaining part (20) is provided on an inner circumferential surface of the housing (2) to retain an outer circumference of the motor (4) at or near one end of the motor (4). A second retaining part (21) retains an outer circumference of a first bearing (13a) that supports a first motor shaft (12a) extending from the one end of the motor (4). A third retaining part (22) is provided on the inner circumferential surface of the housing (2) to retain an outer circumference of the motor (4) at or near the other end of the motor (4). A fourth retaining part (23) retains an outer circumference of a second bearing that supports a second motor shaft (12b) extending from the other end of the motor (4). A first chamber (30) houses a cooling fan (3) and includes a first vent (14). A second chamber (31) includes a second vent (15).