Drill Hammer Gear Shifting via Radial Engagement
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Solution Overview
Problem
The existing drill hammer designs with changeover mechanisms for drilling, chiseling, and hammer-drilling modes suffer from increased structural length, mass, and stress on running gears, leading to reduced service life and efficiency due to axial displacement and friction issues.
Innovation Solution
A compact and robust drill hammer design that eliminates axial displacement of running gears, using a simple cylindrical intermediate shaft with sintered metal gear wheels and roller bearings, and shifting hubs with tooth profiles for easy mode switching, reducing friction and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If axial displacement mechanism is used for gear changeover, then mode switching is achieved, but structural length and mass increase
Solution Approach 1:
The patent transitions from axial displacement (one-dimensional movement) to radial engagement (two-dimensional arrangement). The shifting hub engages gear wheels radially through toothed profiles, eliminating the need for axial displacement and reducing structural length and mass while maintaining mode switching capability
2Adaptability or versatility
If axial displacement of running gears is used, then gear changeover is achieved, but stress on gears increases and service life shortens
Solution Approach 1:
The patent eliminates axial displacement of running gears by implementing radial engagement through toothed profiles on the shifting hub. This dimensional change prevents additional stress on gear teeth during mode switching, maintaining gear service life while achieving gear changeover functionality
3Stability of the object's composition
If constant axial bracing of shifting means is used, then shifting positions are maintained, but friction increases and efficiency decreases
Solution Approach 1:
The patent replaces axial bracing with radial toothed profile engagement. The shifting hub engages gear wheels through radial tooth interfaces rather than axial spring bracing, eliminating constant friction while maintaining stable shifting positions through the geometric constraint of the toothed profiles
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 design results in a more efficient, lighter, and economically produced drill hammer with improved mode switching and reduced wear, maintaining efficiency and extending the service life of the gear mechanism.
Implementation Method 1
a drive pinion (24) of an intermediate shaft (28) that is supported by one end in an intermediate flange (25), via a needle bearing, in a manner fixed against relative rotation, and in engagement with a motor pinion (24)
Implementation Method 2
a roller bearing, in a manner fixed against relative rotation, and in engagement with a motor pinion (24)
Implementation Method 3
a wobble gear wheel (38) that is freely rotatable on the intermediate shaft (28)
Implementation Method 4
with a spring element (76), in particular a torsion spring, that acts on the shifting hubs (34, 134)
Data Source
AI summary
A drill hammer for the three operation modes of drilling, chiseling, and hammer-drilling has a motor with a motor shaft; a gear with an intermediate shaft, a driving gear wheel, a toothed slaving shaft , a shifting hub, and a driven gear wheel; a percussion mechanism with a wobble disk and a wobble gear wheel; and a driven shaft with a driving gear wheel and a drill chuck. The gear is configured to be changed over easily without axial displacement of running gears that mesh with one another so that the drill hammer is more robust, shorter or more compact, and lighter in weight. The drill hammer is thus simply and economically constructed and whose efficiency is not impaired by the gear shifting mechanism.