Handheld Power Tool Planetary Gear Speed Division
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Solution Overview
Problem
Existing handheld power tools with gear arrangements and hammer mechanisms struggle to optimize speed for impact drives, leading to suboptimal drilling progress and increased external dimensions.
Innovation Solution
A handheld power tool design featuring a planetary gear stage with a sun gear, ring gear, and planet gears that generates integer ratios between output rotary movements, combined with a resilient lever element and eccentric hammer mechanism, allowing for efficient impact drilling with reduced size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional gear arrangement and hammer mechanism are used, then the tool can perform impact drilling, but the external dimensions become larger and the drilling progress is suboptimal
Solution Approach 1:
The patent implements nested doll by placing the hammer mechanism components (hammer, lever element, eccentric element) within the internal cavity of the tool housing, surrounding the tool spindle. The gear arrangement is integrated into the housing structure with planet gears arranged radially around the spindle axis. This nested arrangement maximizes the use of internal space, achieving compact external dimensions while maintaining high productivity through effective impact drilling capability.
Solution Approach 2:
The patent transitions from conventional linear or radial arrangements to a three-dimensional spatial configuration. The hammer mechanism operates in a rotational dimension around the spindle axis, with the lever element pivoting in a plane perpendicular to the spindle. The eccentric element converts rotational motion into linear impact motion through dimensional transformation. This multi-dimensional arrangement optimizes space utilization and achieves compact tool dimensions without compromising drilling performance.
2Productivity
If the gear arrangement is designed to provide high impact speed, then drilling progress improves, but the tool becomes larger and heavier
Solution Approach 1:
The planetary gear arrangement serves multiple functions simultaneously: it provides speed multiplication for the hammer mechanism, transmits rotational motion from the motor, and supports the tool spindle. The same gear components are used to generate both the high-speed impact motion and the rotary drilling motion, eliminating the need for separate dedicated mechanisms. This multi-functionality reduces the overall number of components, minimizing tool weight while maintaining high productivity.
Solution Approach 2:
The patent utilizes parameter changes in the planetary gear system to optimize performance. By varying the tooth counts of the sun gear, ring gear, and planet gears, the system achieves different speed ratios and torque multiplication factors. The gear ratio is specifically designed to provide high impact speed for the hammer mechanism while keeping the overall device compact and lightweight. This parameter optimization allows high number of impacts without increasing tool weight.
3Length of moving object
If a compact design is implemented, then external dimensions are reduced, but the complexity of the gear arrangement increases
Solution Approach 1:
The patent merges the hammer mechanism and gear arrangement into a single integrated assembly within the tool housing. The hammer, lever element, and eccentric element are combined with the planetary gear system such that they share common mounting structures and motion transmission paths. The sun gear, ring gear, and planet gears are arranged to simultaneously engage with the hammer mechanism and the tool spindle, creating a unified structure that reduces overall tool size without proportionally increasing complexity.
Solution Approach 2:
The gear arrangement is segmented into modular planetary gear stages that can be independently designed and assembled. The sun gear assembly, ring gear assembly, and planet gear assemblies are distinct modules that can be manufactured separately and then integrated into the compact housing. This segmentation allows for simplified manufacturing and assembly processes, reducing the practical complexity despite the compact design requirements.
4Productivity
If the hammer mechanism uses resilient and pneumatic elements, then impact efficiency increases, but device complexity increases
Solution Approach 1:
The resilient lever element and pneumatic/hydraulic elements are designed to automatically return the hammer to its initial position after impact without requiring external actuation. The resilient element stores and releases energy cyclically, while the pneumatic/hydraulic system uses pressure differentials to achieve automatic resetting. This self-service capability eliminates the need for additional control mechanisms, reducing device complexity while maintaining high impact efficiency through the resilient and pneumatic elements.
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 achieves a high number of impacts and effective drilling progress with a compact and lightweight tool, minimizing wear on the gear arrangement and enabling easy switching between drilling and hammering modes.
Implementation Method 1
The gear arrangement has at least one gear stage which is designed as a planetary gear stage
Implementation Method 2
The hammer mechanism is designed as an eccentric hammer mechanism which is provided to generate a linear movement perpendicular to the axis of rotation of the rotational movement from a rotational movement
Implementation Method 3
The hammer mechanism has a resilient lever element which is mounted pivotably about a pivot axis and is provided to drive a hammer of the hammer mechanism
Data Source
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AI summary
The invention relates to a hand-held power tool, in particular a rotary hammer drill with a transmission arrangement (14a; 14b), a hammer mechanism (16a; 16b) and a tool spindle (18a; 18b). It is proposed that the transmission arrangement (14a; 14b) have at least one gear stage element (132a; 132b) for the purpose of dividing a flow of power to provide different rotational speeds for a percussion drive and a rotary drive.