Electric Tool Controller Cooling via Centrifugal Fan Airflow
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Solution Overview
Problem
Existing electric tools with battery packs face challenges in cooling their controllers while minimizing size, particularly for brushless motors that generate heat and require large controllers to manage over-discharge and over-current states, which affects their service life and operational efficiency.
Innovation Solution
Incorporating a centrifugal fan driven by the electric motor to direct airflow towards the controller, positioning it to maximize cooling efficiency while reducing the tool's overall size by positioning the controller on the rear side of the motor and extending its shorter side along the machining direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller size is increased to manage brushless motor control and prevent over-discharge/over-current states, then the reliability and control capability are improved, but the overall tool size increases
Solution Approach 1:
The controller is repositioned from a conventional location to the rear side of the motor along the machining direction, utilizing previously unused spatial dimension. This dimensional reconfiguration allows the controller to occupy space that does not interfere with the cutting path or handle ergonomics, thereby maintaining small tool size while accommodating the larger controller required for brushless motor control
2Temperature
If the controller is positioned to be cooled by centrifugal fan airflow, then the temperature control is improved, but the controller positioning options are constrained
Solution Approach 1:
The controller positioning simultaneously achieves two functions: it is located in the airflow path of the centrifugal fan for effective cooling, and it is positioned on the rear side of the motor to maintain compact tool dimensions. This merging of cooling requirement satisfaction with spatial optimization eliminates the need for separate cooling ducts or complex positioning mechanisms
Solution Approach 2:
The centrifugal fan, which already operates to cool the motor, is utilized to also cool the controller by simply positioning the controller in its airflow path. This self-service approach uses the existing fan system to provide dual cooling function without requiring additional cooling components or increasing system complexity
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 effectively cools the controller, reduces the tool's size, and enhances operational ease by maintaining the balance and weight distribution, thereby improving handling and machining efficiency.
Implementation Method 1
a centrifugal fan rotatably driven by the electric motor for producing a flow of air
Data Source
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AI summary
An electric tool (11A; 11B; 11C) may include a tool main body (13A; 13B; 13C) configured to be able to mount a battery pack (60). The tool main body (13A; 13B; 13C) may include an electric motor (21; 21B; 21C), a controller (56; 56B; 56C) for controlling the electric motor (21; 21B; 21C), and a centrifugal fan (27; 27B; 27C) rotatably driven by the electric motor (21; 21B; 21C) for producing a flow of air. The controller (56; 56B; 56C) may be positioned such that the flow of air produced by the centrifugal fan (27; 27B; 27C) is applied to at least a part of the controller (56; 56B; 56C).