Actuation Mechanism for Driven Machine Tool Switching
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Solution Overview
Problem
Existing driven machine tools, such as angle grinders, face difficulties in safely switching on and off in environments with high dust levels due to the accumulation of dust particles impeding the movement of angled switching rods, requiring high transverse forces for actuation.
Innovation Solution
The actuating mechanism incorporates a shift rod that displaces along the longitudinal axis and a pivotable shift lever, reducing the need for high transverse forces by leveraging the movement to pivot the drive switch, allowing for safer and easier operation with reduced friction through a rounded contour connection and potential use of friction-reducing materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an angled switching rod is used to actuate the drive switch, then the actuation mechanism is simple, but dust particles accumulate in the actuating mechanism causing the shift rod to be impeded and requiring high transverse forces for actuation
Solution Approach 1:
A Bowden cable is introduced as an intermediary element to transmit the actuating force from the handle area to the drive switch in the device body. This allows the switching element to be decoupled into two parts: an actuating part in the handle and a switching part in the device body, preventing dust accumulation at the actuation point while maintaining simple mechanism design
Solution Approach 2:
The switching mechanism is divided into separate segments: the Bowden cable transmits force separately from the switching element, and the switching element itself is split into an actuating section and a switching section. This segmentation allows each component to be optimized independently, with the actuating mechanism protected from dust while the switching mechanism remains simple
2Device complexity
If the shift rod is directly connected to the drive switch, then the actuation mechanism is simple, but high transverse forces are required to shift the drive switch
Solution Approach 1:
The Bowden cable acts as a mediator that transmits axial force from the handle to the switching element, converting the required transverse force into an axial pulling force that is easier to apply and reduces the force burden on the switching mechanism
Solution Approach 2:
Instead of pushing the drive switch directly with transverse force, the system inverts the approach by using a Bowden cable to pull the switching element axially, reversing the force direction and application method to reduce required force
3Reliability
If a Bowden cable is used to connect the switching element in the handle to the drive switch in the device body, then dust accumulation is reduced, but the device complexity increases
Solution Approach 1:
The Bowden cable serves multiple functions: it transmits actuating force, allows decoupling of the switching mechanism, and protects against dust accumulation. This multi-functionality justifies the added complexity by providing multiple benefits from a single component
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 solution ensures safe and effortless switching of the machine tool even in dusty environments by minimizing the forces required for operation and reducing stress on the actuating mechanism, while allowing dust to be directed away from critical areas.
Implementation Method 1
a shift lever (26) which is pivotably mounted in a bearing point (28) on the housing (14) and has at least one lever arm (26a)
Implementation Method 2
The shift rod (24) is coupled to the at least one lever arm (26a) and is able to pivot it as a result of its displacement. By using a shift lever, the point of force application or point of force application on the shift rod is shifted in the direction of the actuation axis. This results in significantly lower transverse forces, which have to be absorbed by the bearing.
Implementation Method 3
The shift lever (26) can have a rounded outer contour at the free end of the coupled lever arm, and the recess on the shift rod can have a substantially corresponding contour. By providing such a rounded outer contour, which engages in an essentially corresponding inner contour of the recess on the shift rod, an articulated connection of the shift rod with the shift lever is achieved, in which a relative movement of the shift lever to the shift rod (due to the pivoting movements of the lever) subjected to less friction.
Data Source
AI summary
The tool (10) has a drive unit (18) including a drive switch (16) for switching on and off the drive unit. Housing (14), in which the drive unit is partially received, and an actuation mechanism (22) actuates the drive switch. The actuation mechanism includes a switching rod (24), which is moved along a longitudinal axis (L) of the housing, protrudes through a recess of the housing and includes an actuation portion. A switching lever (26) is pivotably supported at a bearing point (28) and includes a lever arm, and the rod is connected to the lever arm, and pivotally moves. An independent claim is also included for an actuation mechanism for actuating a drive switch of a driven machine tool.