Sander Counterweight Centroid Adjustment for Torque Reduction
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Solution Overview
Problem
Existing sanders face challenges in reducing vibration and weight, leading to increased torque and discomfort during operation, which necessitates additional counterweights to balance the system.
Innovation Solution
The sander design incorporates a counterweight with a centroid adjusted to be closer to the lower surface of the base plate, reducing torque and weight, and featuring a fan with a reduced density and optimized weight distribution to minimize overall sander weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the balancing structure is directly fixedly connected to or integrally formed with the eccentric element and/or the fan assembly, then the installation is facilitated and the structure is simplified, but the centroid of the balancing structure becomes higher, increasing the torque between the centroids and requiring additional counterweight, which increases the weight of the sander
Solution Approach 1:
The patent applies the counterweight principle by providing a balancing structure with a specific mass distribution. The balancing structure includes a counterweight portion that is eccentrically positioned relative to the motor shaft rotation center, creating a balancing moment that counteracts the unbalanced moment generated by the base plate assembly and sandpaper. This allows the sander to achieve vibration reduction without requiring additional counterweight components, thereby avoiding weight increase while maintaining installation convenience.
2Device complexity
If the balancing structure is directly fixedly connected to or integrally formed with the eccentric element and/or the fan assembly, then the structure is simplified, but the distance between the centroid of the balancing structure and the centroid of the base plate assembly increases, increasing the torque between the centroids
Solution Approach 1:
The patent applies local quality by optimizing the mass distribution within the balancing structure itself. The balancing structure is designed with a specific mass distribution where the counterweight portion is eccentrically positioned at a predetermined distance from the motor shaft rotation center. This local optimization of mass distribution allows the balancing structure to generate sufficient balancing moment while keeping the centroid distance and resulting torque within acceptable limits, all while maintaining structural simplicity.
3Reliability
If additional counterweight is added to balance the torque and ensure the smooth operation of the sander, then the vibration is reduced, but the weight of the sander increases, affecting the hand feeling of operation
Solution Approach 1:
The patent integrates the counterweight function directly into the balancing structure that is already present in the sander. The balancing structure includes a counterweight portion with specific mass and eccentric position that provides the necessary balancing moment to counteract the unbalanced moment from the base plate assembly. This integration eliminates the need for separate additional counterweight components, thereby maintaining smooth operation while avoiding the weight increase that would affect hand feeling during operation.
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 reduces the torque between the counterweight and base plate assembly, decreases the overall weight of the sander, and enhances user comfort and operational efficiency by minimizing the need for additional counterweights.
Implementation Method 1
The eccentric element drives the base plate assembly to move about a motor axis of the electric motor
Implementation Method 2
The fan assembly is used for generating a dust collection airflow and a heat dissipation airflow when the electric motor operates
Data Source
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AI summary
Provided is a sander. The sander includes a housing; an electric motor at least partially disposed in the housing and used for providing a power source, where the electric motor includes a motor shaft that rotates about a motor axis; a fan assembly including a fan connected to the electric motor; an eccentric element driven by the electric motor, where the eccentric element has a central axis deviating from the motor axis; and a base plate assembly including a base plate, a sanding member fixed to a lower surface of the base plate, and a support for supporting the eccentric element, where the support includes a first end surface and a second end surface opposite to each other, and the second end surface is disposed on a side of the support facing the lower surface relative to the first end surface. The sander further includes a counterweight connected to the eccentric element and driven by the electric motor to rotate about the central axis. The ratio of the distance from the centroid of the counterweight to the lower surface of the base plate to the distance from the first end surface of the support to the lower surface of the base plate is greater than or equal to 0.2 and less than or equal to 0.4.