Sealed Rotary Switch Housing for Dust-Resistant Power Tools
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Solution Overview
Problem
Magnetic switching actuators in hand-held machine tools tend to attract ferromagnetic dust and chips, leading to tool malfunction, as existing solutions do not effectively prevent environmental contaminants from entering the switch chamber.
Innovation Solution
A switch design incorporating a pivot bearing with a sealing mechanism, such as a labyrinth seal, to prevent dust and ferromagnetic particles from entering the switch chamber, while allowing for adjustable direction of rotation of the drive motor using a transmission element with anti-displacement contours and a separate actuating element for speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic switching actuator is used in the switch chamber, then the drive motor can be switched on and its speed changed, but ferromagnetic dust and chips are attracted to the actuator, rendering the power tool unusable
Solution Approach 1:
The switch chamber is divided into a sealed interior space and the external environment through a closed chamber design with a passage opening. The actuating element is segmented into a sealed portion inside the chamber and an external actuation portion, allowing the magnetic actuator to be isolated from contaminants while maintaining functionality.
Solution Approach 2:
A transmission element acts as an intermediary between the external actuating element and the internal switching actuator. This transmission element transfers the actuation force through the sealed passage opening without allowing direct contact between external contaminants and the magnetic actuator, thus protecting the switching mechanism.
2Object-affected harmful factors
If the switch chamber is completely sealed, then ferromagnetic dust is prevented from entering, but the actuating element cannot be connected to the switching actuator
Solution Approach 1:
The transmission element is extracted through the passage opening, allowing it to extend from the sealed switch chamber to the external environment. This extraction enables the actuating element to be operated externally while the switching actuator remains protected inside the sealed chamber, maintaining both sealing integrity and operational accessibility.
3Ease of operation
If a passage opening is provided for the actuating element, then the switch can be operated externally, but dust and ferromagnetic particles can enter the switch chamber
Solution Approach 1:
A seal is provided at the passage opening that flexes or deforms to accommodate the actuating element's movement while maintaining the sealing barrier. This flexible sealing mechanism allows external actuation through the passage opening while preventing dust and ferromagnetic particles from entering the switch chamber.
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 effectively seals the switch chamber from environmental contaminants, ensuring reliable operation by preventing dust accumulation and allowing precise control of the drive motor's direction and speed, thus extending the tool's usability in dusty environments.
Implementation Method 1
Magnetic switching actuators in hand-held machine tools tend to attract ferromagnetic dust and chips
Implementation Method 2
The pivot bearing makes it easy, for example, to design the switch as a direction of rotation switch
Data Source
Figure 1~2
Figure 3~4
Figure 5~10
AI summary
The invention relates to a switch (30) for a hand-held power tool (10) or as a component of a hand-held power tool (10), which has an electric drive motor (16) that can be switched by the switch (30). The switch (30) has a switch housing (33) with a switch chamber (35) in which a switch actuator (75) that can be moved between at least two switch positions (ML, MR) is arranged in order to actuate an electric switch element, said switch actuator being kinetically coupled, by means of a transmission element (70), to a switch (30) actuation element (32), which is arranged outside the switch housing (33) and can be moved between at least two actuation positions (R, L), wherein the transmission element (70) passes through a through-opening (54) on a wall of the switch housing (33) such that the switch actuator (75) can be moved by moving the actuation element (32) in order to actuate the switch element (24). A rotary bearing (77) is arranged in the through-opening (54), the transmission element (70) being rotatably mounted on the rotary bearing about a rotational axis (D).