Hand-held Power Tool Impact Energy Adjustment via Gear Ratio
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Solution Overview
Problem
Existing rotary hammers with eccentric impact mechanisms have limitations in adapting to different applications due to fixed impact energy and power levels, which restrict their versatility and efficiency across various tasks.
Innovation Solution
The design incorporates a system where the second hand-held power tool has a mechanically reduced single impact energy and impact power compared to the first, achieved through adjustments in gear unit eccentricity, crank stroke, and air spring length, while maintaining identical impact frequency and B-impact damping systems, allowing for a more versatile application range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the impact energy and power are fixed in existing rotary hammers, then the impact frequency can be maintained consistently, but the versatility and efficiency across various tasks are restricted
Solution Approach 1:
The patent applies dynamics by making the impact energy adjustable through variable gear ratios. The gear mechanism allows the transmission ratio between the motor and impactor to be changed, enabling the same device to deliver different impact energy levels while maintaining consistent impact frequency. This dynamic adjustment capability resolves the contradiction by providing adaptability across tasks without requiring multiple fixed-design tools.
Solution Approach 2:
The patent implements parameter changes by modifying the transmission ratio in the gear mechanism to adjust impact energy. By changing the gear ratio parameter, the system can reduce or increase the impact energy delivered to the insert tool while keeping the motor speed and impact frequency constant. This parameter adjustment enables versatility across different applications without increasing device complexity.
2Adaptability or versatility
If the single impact energy is mechanically reduced through gear adjustments, then the tool can be adapted to different application areas, but the device complexity increases due to additional gear units
Solution Approach 1:
The patent applies universality by designing a gear mechanism that can serve multiple functions: it transmits motor power to the impactor, enables adjustment of impact energy levels, and maintains consistent impact frequency. By making the gear unit adjustable, a single tool design can handle multiple application scenarios from low-energy precision work to high-energy heavy-duty tasks, reducing the need for multiple specialized tools.
Solution Approach 2:
The patent uses dynamics by implementing an adjustable gear ratio system that allows the transmission characteristics to be changed during operation or between tasks. This dynamic capability enables the same mechanical structure to adapt to different application requirements by modifying the energy transmission ratio, thereby achieving versatility without proportionally increasing device complexity.
3Force
If the crank stroke is reduced to lower impact energy, then the individual impact energy is reduced, but the air spring length and damping system must be adjusted accordingly
Solution Approach 1:
The patent implements parameter changes by adjusting the crank stroke dimension to control impact energy. By modifying the crank stroke parameter in the gear mechanism, the system reduces the distance over which the impactor accelerates, thereby delivering lower impact energy. This parameter adjustment is complemented by corresponding adjustments to air spring length and damping characteristics to maintain proper system balance and performance.
Solution Approach 2:
The patent applies local quality by making specific modifications to the impact mechanism components - reducing crank stroke for lower impact energy while adjusting air spring length and damping system characteristics locally. These targeted local adjustments allow the system to optimize impact energy delivery for specific applications without redesigning the entire mechanism, thereby managing complexity effectively.
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 approach enables the second hand-held power tool to be easily adapted to different areas of application with reduced individual impact energy, maintaining consistent impact frequency and optimizing the B-impact damping system, thus enhancing its operational versatility and efficiency.
Implementation Method 1
a piston of a second gear unit, wherein the striker can be driven in a linear oscillating manner via the piston
Implementation Method 2
the guide tube is rotatably coupled to the motor via a first gear unit and wherein the striker can be driven in a linear oscillating manner via a piston of a second gear unit
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The invention relates to a system comprising a first hand-held power tool (10) and a second hand-held power tool, each having a percussion mechanism (36), a motor (26), and a transmission (28), which comprises the striking mechanism and is designed to transfer a driving motion of the motor to an insert tool (30) held in a tool holder (12), each transmission having a guide tube (50) which is identical in some regions along a working axis (58), in which guide tube a striker (44) is mounted for axial movement, the guide tube being rotatably coupled to the motor by means of a first transmission unit (32) and the striker being drivable in a linearly oscillating manner by means of a piston (52) of a second transmission unit (34), a ratio between a diameter (14) of the tool holder and a diameter of the guide tube being 1.8 times greater in the first hand-held power tool than in the second hand-held power tool. An individual amount of striking energy of the second hand-held power tool is mechanically reduced in comparison with an individual amount of striking energy of the first hand-held power tool.