Metal-Weighted Fan Wheel for Stable Spindle Locking
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Solution Overview
Problem
Conventional handheld power tools face challenges in maintaining a stable spindle locking mechanism and effective cooling, leading to inadequate response behavior and increased wear due to insufficient inertia in the fan wheel.
Innovation Solution
Incorporating a fan wheel with at least 20% by volume of metal, such as zinc, zinc alloy, brass, or steel, to increase inertia and improve the response behavior of the spindle locking device, combined with a planetary gear set and torque clutch for enhanced stability and overload protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a plastic fan wheel is used for cooling the drive motor, then the weight is reduced, but the inertia is insufficient leading to poor response behavior of the spindle locking device
Solution Approach 1:
The fan wheel is constructed as a composite structure with a plastic base material and metal insertions (brass or steel pins). This composite approach combines the weight advantages of plastic with the inertia benefits of metal, resolving the contradiction between lightweight design and sufficient rotational inertia for reliable spindle locking response.
2Reliability
If the fan wheel is made of metal to increase inertia, then the response behavior of the spindle locking device improves, but the weight increases
Solution Approach 1:
Instead of making the entire fan wheel from metal, metal insertions (pins) are strategically placed at specific locations on the plastic fan wheel. This local application of metal material provides the necessary inertia enhancement while minimizing overall weight increase, as the metal is concentrated only where needed for rotational mass.
3Productivity
If the drive spindle is allowed to rotate freely during operation, then the tool can operate smoothly, but the spindle cannot be locked for tool changes
Solution Approach 1:
The spindle locking device incorporates a movable blocking member that can transition between locked and unlocked positions. During operation, the blocking member is retracted to allow free rotation; during tool changes, it engages with the clamping surface to lock the spindle. This dynamic switching capability resolves the contradiction between smooth operation and ease of tool changes.
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 solution enhances the reliability and responsiveness of the spindle locking device, reduces wear, and improves the overall performance by increasing the rotary inertia and balancing the device, while preventing twisting and torque fluctuations.
Implementation Method 1
it is possible to achieve an increase in a corresponding inertia of the fan wheel by designing the fan wheel to be made at least 20 percent by volume of metal, thus achieving at least an improvement of a response behavior of the spindle locking device
Implementation Method 2
A fan wheel is provided which is intended at least for cooling the drive motor
Data Source
AI summary
A handheld power tool including a tool housing, in which a drive motor for driving a drive spindle is situated, the drive spindle being assigned a tool holder for accommodating an insertion tool and the drive spindle being assigned a spindle locking device which is designed to prevent the drive spindle from twisting in relation to the tool housing during a spindle locking mode, a fan wheel is provided which is intended at least for cooling the drive motor, at least 20 percent by volume of the fan wheel including a metal having a density of greater than or equal to 3.5 g/cm3.