Hand-Held Grinder Eccentric Gear With Directional Freewheel Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switching between operating modes in hand-held power tools, such as grinding and polishing machines, is complex and inefficient.
Innovation Solution
A mechanism that allows switching between forced rotation eccentric and freewheel modes by reversing the direction of rotation of the tool shaft, utilizing a freewheel device to lock or unlock the rolling elements, and incorporating a braking system to control the mobility of the tool shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional switching mechanism is used to switch between forced rotation eccentric mode and freewheel mode, then mode switching can be achieved, but the device complexity increases and the switching process becomes cumbersome
Solution Approach 1:
Instead of using a traditional switching mechanism to engage/disengage the forced rotation guide, the invention reverses the approach: the forced rotation guide remains permanently engaged, and mode switching is achieved by selectively locking or unlocking the tool shaft using a freewheel device. This inversion eliminates the need for complex switching mechanisms while achieving the same functional result.
Solution Approach 2:
The freewheel device automatically locks or unlocks the tool shaft based on the direction of rotation, enabling mode switching without requiring external control mechanisms. The system self-regulates the operating mode through the rotational direction-dependent locking behavior of the freewheel device, simplifying the overall control structure.
2Stability of the object's composition
If the forced rotation guide permanently guides the tool shaft, then the tool shaft is always constrained, but the tool shaft cannot rotate freely in freewheel mode
Solution Approach 1:
The system dynamically adjusts the constraint state of the tool shaft based on the operating mode. In forced rotation eccentric mode, the freewheel device locks the tool shaft to maintain stable guidance through the forced rotation guide. In freewheel mode, the freewheel device unlocks, allowing the tool shaft to rotate freely while the forced rotation guide remains in place but inactive. This dynamic switching enables both stable guidance and rotation freedom as needed.
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
Enables seamless switching between operating modes with minimal mechanical complexity, enhancing operational efficiency and reducing wear on the tool and workpiece.
Implementation Method 1
the rolling element supported on the tool shaft to drive the rolling element supported on the machine housing along with it in rotation
Implementation Method 2
it is also possible for the rolling element associated with the tool shaft to be rotatable in the second direction of rotation, so that it can be held stationary or essentially stationary by the rolling element supported on the machine housing and non-rotatable in the second direction of rotation
Data Source
Figure 1~2
Figure 3~7
Figure 8
AI summary
The invention relates to a hand-held power tool, in particular a grinding machine (10), with an eccentric gear (40) arranged in a machine housing (11) and an electric or pneumatic drive motor (30) for rotary driving of a drive shaft (35) of the eccentric gear (40) about a drive axis (A), wherein the eccentric gear (40) has a tool shaft (50) which is rotatably mounted eccentrically on the drive shaft (35) by means of at least one tool shaft bearing (42, 44) to perform eccentric movements and has a tool holder (51) for a disc tool (14), wherein a forced rotation guide (54) is provided which, in a forced rotation eccentric mode, forces rotational movements of the tool shaft (50) with respect to the machine housing (11) by means of a rolling element (55) of the forced rotation guide (54) engaging another rolling element (57) of the forced rotation guide (54). shifts the burden,wherein one rolling element (57) is supported on the machine housing (11) and the other rolling element (55) is supported on the tool shaft (50). A freewheeling device (62) is provided between at least one of the rolling elements (57) and the tool shaft (50) or the machine housing (11). This freewheeling device couples the at least one rolling element (57) to the machine housing (11) or the tool shaft (50) in a first direction of rotation of the tool shaft (50), which corresponds to a locking direction of the freewheeling device (62), so that one rolling element (55) supported on the tool shaft (50) can roll on the other rolling element (57) supported on the machine housing (11). In a second direction of rotation of the tool shaft (50), which corresponds to a freewheeling direction of the freewheeling device (62), the freewheeling device (62) is rotatably released, so that the tool shaft (50) can rotate with respect to the machine housing (11) without relative rotation of the rolling elements (55, 57) relative to each other.