Coaxial Rotary Drive Hammer Mechanism for Compact Power Tools
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Solution Overview
Problem
Existing hand-held power tools, such as rotary hammer drills, face challenges in achieving a compact design while maintaining high impact energy and low vibration, often resulting in tools that are heavy and cumbersome.
Innovation Solution
The design incorporates a coaxial rotary drive element with a hammer mechanism that includes an eccentric element and a spring-elastic lever element, allowing for a compact, lightweight tool with high impact energy and low vibration, featuring a detachable coupling device for switching between drilling and screwing modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a compact design is pursued with coaxial arrangement of rotary drive element and tool spindle, then tool length and overall size are reduced, but achieving high impact energy becomes more difficult
Solution Approach 1:
The hammer mechanism is nested within the coaxial rotary drive element structure. The linearly moving hammer is positioned inside the rotary drive element's cylindrical space, allowing the impact mechanism to be contained within the rotational mechanism without requiring additional radial or axial space. This nesting enables compact tool length while maintaining sufficient impact energy through the eccentric element's oscillating motion.
Solution Approach 2:
The hammer mechanism transitions from traditional orthogonal arrangement to coaxial arrangement, utilizing the radial dimension of the rotary drive element. The eccentric element converts rotational motion into linear reciprocating motion of the hammer along the axial direction, while the hammer's oscillating path utilizes the radial space within the rotary element. This dimensional reorganization achieves compact length without sacrificing impact energy.
2Weight of moving object
If tool mass is reduced for lightweight operation, then ease of handling is improved, but vibration control becomes more challenging
Solution Approach 1:
The eccentric element introduces intentional asymmetry into the hammer mechanism's mass distribution and motion path. The hammer oscillates along an eccentric path rather than a perfectly symmetric linear path, which helps distribute vibrational forces more evenly over time. This asymmetric motion pattern, combined with the spring element's damping, reduces peak vibrations while maintaining lightweight construction.
Solution Approach 2:
The spring element is positioned between the hammer and the tool spindle to provide beforehand cushioning. This elastic element absorbs and dampens impact vibrations before they are transmitted to the tool body and user. The spring's pre-compression and elastic properties enable vibration reduction while maintaining the lightweight design, as the cushioning function is integrated into the existing hammer mechanism rather than requiring separate heavy damping components.
3Adaptability or versatility
If a detachable coupling device is used for switching between drilling and screwing modes, then adaptability is improved, but device complexity increases
Solution Approach 1:
The detachable coupling device serves multiple functions: it connects the hammer mechanism to the rotary drive element for impact drilling, and can be detached or reconfigured for screwing operations without impact. This single coupling mechanism enables both drilling and screwing modes, providing versatility while maintaining relatively simple construction through its modular, detachable design that integrates with the existing coaxial arrangement.
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 configuration enables a powerful, lightweight hand-held power tool with enhanced drilling efficiency and reduced wear, capable of high impact energy and comfortable operation, while minimizing tool mass and vibration.
Implementation Method 1
a hammer mechanism (16) having a rotary drive element (52) with an axis of rotation (34), which is arranged coaxially to at least part of a tool spindle (18)... The hammer mechanism moves the hammer resiliently and/or pneumatically and/or hydraulically by means of a connecting link device, by means of a wobble bearing and/or advantageously by means of an eccentric element
Implementation Method 2
The hammer mechanism moves the hammer resiliently and/or pneumatically and/or hydraulically
Implementation Method 3
hammer mechanism moves the hammer resiliently and/or pneumatically and/or hydraulically by means of a connecting link device, by means of a wobble bearing and/or advantageously by means of an eccentric element
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 torque setting unit (12a, 12b), a transmission arrangement (14a; 14b), a hammer mechanism (16a; 16b) and a tool spindle (18a; 18b). It is proposed that the hammer mechanism (16a; 16b) have a rotary driving element (52a; 52b) with a rotation axis (34a; 34b) disposed co-axially to at least a part of the tool spindle (18a; 18b).