Hand-held work device with a blowpipe
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Solution Overview
Problem
Existing hand-held blower devices have a large overall length due to the arrangement of the drive motor and cooling air system, which complicates the design and makes them less compact.
Innovation Solution
The extraction opening for cooling air is positioned downstream of the guide wheel, allowing cooling air to be extracted under overpressure from the working airflow, eliminating the need for an additional fan wheel and enabling a compact design. The drive motor can be placed near the impeller or guide wheel, and the engine compartment is designed to maintain sufficient cooling pressure through geometric adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the drive motor and cooling air system are arranged in a conventional configuration, then the cooling function is provided, but the overall length of the blower becomes very large
Solution Approach 1:
The drive motor is integrated into the blower assembly with the impeller and guide wheel, eliminating the need for separate cooling components. The motor housing forms part of the blower structure, and the cooling air pathway is incorporated into the existing airflow channels, merging multiple functions into a single compact unit.
Solution Approach 2:
The drive motor is positioned within the blower housing such that the motor housing is surrounded by the annular space between the impeller and guide wheel. The cooling air flows through the motor housing from the annular space, creating a nested arrangement where the motor is embedded within the blower structure, maximizing space utilization and minimizing overall length.
2Device complexity
If the drive motor is positioned upstream of the impeller, then the cooling air flow is simplified, but the device complexity and length increase
Solution Approach 1:
Instead of positioning the drive motor upstream of the impeller as in conventional designs, the motor is positioned downstream between the impeller and guide wheel. This inverted arrangement allows the motor to be integrated into the high-pressure region of the airflow, enabling compact design while maintaining effective cooling through the pressure differential.
3Temperature
If an additional fan wheel is added to convey cooling air, then the cooling effectiveness is improved, but the device complexity increases
Solution Approach 1:
The blower's main impeller and guide wheel create a pressure differential that automatically drives cooling air through the motor housing without requiring a separate fan wheel. The working air flow itself serves the dual function of both power transmission and cooling air conveyance, eliminating the need for additional moving parts.
Solution Approach 2:
The annular space between the impeller and guide wheel serves multiple functions: it conveys the working air flow for power transmission, provides the cooling air pathway through the motor housing, and creates the pressure differential needed for effective cooling. This multi-functional design eliminates the need for dedicated cooling components.
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 results in a simpler, more compact hand-held tool with effective cooling of the drive motor, reduced contamination risk, and improved airflow cleanliness, while maintaining efficient operation in dirty environments.
Implementation Method 1
The removal opening and the outflow opening are arranged in such a way that during operation the pressure at the removal opening is greater than the pressure at the outflow opening. Due to the fact that the extraction opening for cooling air is arranged downstream of the guide wheel, cooling air can be extracted from the working air flow under overpressure. This overpressure can be used to effect the flow of cooling air through the engine compartment.
Implementation Method 2
During operation, due to its rotation, the impeller ejects dirt particles outwards in relation to the axis of rotation of the impeller. As a result, the air in the central area of the air flow is comparatively clean and low in dirt particles.
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
A hand-held tool has a blower tube (13) in which a blower (9) is arranged. The blower (9) delivers a working airflow through the blower tube (13) and has at least one impeller (12) driven by a drive motor (10) to rotate about a rotary axis (28) and at least one guide vane (11) held stationary in the blower tube (13) of the tool. The guide vane (11) is arranged downstream of the impeller (12) with respect to the flow direction (22) of the working airflow through the blower tube (13). The drive motor (10) is an electric motor and is arranged in a motor compartment (26) within the blower tube (13). Downstream of the guide wheel (11) the working device has a cooling air outlet (18) for the drive motor, through which an annular space (27) formed between the blow tube (13) and the motor compartment (26) is connected to the motor compartment (26).The engine compartment (26) has at least one outlet opening (23, 33, 53, 63) for cooling air, which is arranged upstream of the intake opening (18). The intake opening (18) and the outlet opening (23, 33, 53, 63) are arranged such that, during operation, the pressure (p5) at the intake opening (18) is greater than the pressure (p2, pa) at the outlet opening (23, 33, 53, 63).