Portable Power Tool Mode Setting Mechanism Axial Play
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Solution Overview
Problem
Existing hand-held power tools face challenges in maintaining reliable and precise mode setting over a long period due to axial play between the transmission element and mode setting sleeve, which increases with wear, affecting their performance in percussion drilling, drilling, and screwing modes.
Innovation Solution
A hand-held power tool design featuring a mode setting device with a rotationally fixed actuating element and setting element, where the setting element is coupled to a disk-shaped transmission element that can be axially displaced on a clutch housing, allowing for secure fixation and adjustment between operating modes, reducing the number of components and overall length, and incorporating fixing and blocking elements for reliable axial positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a predetermined axial play is provided between the transmission element and mode setting sleeve, then the mode setting device can be easily manufactured and assembled, but the mode setting precision deteriorates over time due to wear increasing the axial play
Solution Approach 1:
The transmission element is designed to be axially displaceable on the clutch housing, transitioning between a fixed position (in impact drilling and drilling modes) and a displaceable position (in screwdriving mode). This dynamic positioning allows the system to maintain precision when needed while preserving ease of manufacture through inherent axial play.
Solution Approach 2:
The mode setting device is segmented into distinct functional zones: the transmission element with its axial displacement capability, the clutch housing with positioning features, and the mode setting sleeve. This segmentation allows each component to be optimized independently - the transmission element handles precision positioning while the sleeve provides easy manipulation.
2Adaptability or versatility
If multiple separate components are used for mode setting and torque adjustment, then each component can be optimized for its specific function, but the overall device complexity and number of components increases
Solution Approach 1:
The transmission element serves multiple functions simultaneously: it acts as a mode setting component through axial displacement, a torque adjustment element through its interaction with the clutch housing, and a transmission component for power flow control. This merging reduces the total number of components while maintaining functional versatility.
Solution Approach 2:
The clutch housing is designed with universal features that serve multiple purposes: it provides axial positioning for the transmission element, serves as a mounting structure, and enables torque control through its interaction with the transmission element. This multi-functionality reduces overall device complexity.
3Adaptability or versatility
If the transmission element is made axially displaceable for mode adjustment, then mode switching flexibility is improved, but the structural stability and reliability deteriorates due to potential loosening and wear
Solution Approach 1:
The transmission element is pre-configured with axial displacement capability through its design on the clutch housing, allowing it to transition between fixed and mobile states. This preliminary preparation ensures reliable mode switching without requiring complex adjustment mechanisms during operation.
Solution Approach 2:
The clutch housing acts as an intermediary structure between the fixed clutch assembly and the axially displaceable transmission element. It provides a stable mounting surface and positioning features that maintain structural reliability while allowing the transmission element to move axially for mode switching.
Data Source
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AI summary
In a portable power tool (100) for operation in the hammer-drilling, drilling and screwing modes, said portable power tool (100) having a mode-setting device (150) having an actuating element (155) and a setting element (110) and also gearing (120) for driving a drive shaft (140), wherein the actuating element (155) and the setting element (110) are connected together in a rotationally fixed manner and the setting element (110) is coupled to a transmission element (170) at least in one operating mode, said transmission element (170) being mounted on a coupling housing (130) assigned to the gearing (120) and being axially movable on the coupling housing (130) in a screwing position assigned to the screwing mode and being axially fixed to the coupling housing (130) in hammer-drilling and drilling positions assigned to the hammer-drilling and drilling modes, the transmission element (170) is connected to the coupling housing (130) in a rotationally fixed manner and a given operating mode can be set by rotating the setting element (110), wherein the setting element (110) and transmission element (170) are rotatable in relation to one another and the setting element (110) engages around the transmission element (170) at least in sections.