Tangential Impact Mechanism Hammer Mass Segmentation
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Solution Overview
Problem
Tangential impact mechanisms in hand-held power tools, such as impact wrenches, are limited by their resonant operation within a narrow torque range, leading to a restricted effective operating point and increased counter-torque requirements, which complicates handling and requires engine speed adjustments.
Innovation Solution
The introduction of an additional mass coupled to the hammer via a second spring within the tangential impact mechanism, allowing for an increased total mass and spring force while maintaining a constant impact frequency, thereby expanding the torque range without significantly increasing the holding torque or requiring motor speed changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the spring force is increased to increase impact force, then the impact force increases, but the triggering moment increases and counter-torque increases, worsening handling
Solution Approach 1:
The hammer mass is segmented into a main mass and an additional mass that can be detachably coupled. The additional mass is equipped with a second spring that has a smaller spring constant than the first spring. This segmentation allows the system to increase total mass and spring force while the softer second spring compensates for triggering moment increases, resolving the contradiction between impact force and handling ease.
Solution Approach 2:
The spring system uses a composite arrangement of two springs with different characteristics (first spring with higher stiffness, second spring with lower stiffness). This composite spring system provides a compromise between the need for high impact force and the need to maintain acceptable triggering moment, allowing both objectives to be partially achieved simultaneously.
2Power
If the spring force is increased to increase impact force, then the impact force increases, but the triggering torque increases, requiring higher holding torque from the user
Solution Approach 1:
The spring system is segmented into two springs with different stiffness characteristics. The second spring has a smaller spring constant and is designed to have a triggering torque that is at most half of the first spring's triggering torque. This segmentation allows the system to achieve higher total spring force for increased torque output while the softer second spring keeps the additional triggering torque requirement minimal, resolving the contradiction between power output and ease of operation.
3Power
If additional mass is added to increase torque output, then the torque range increases, but the impact frequency changes, affecting operation quality
Solution Approach 1:
The system changes the spring constant parameter by introducing a second spring with a smaller spring constant to compensate for the added mass. The second spring is specifically designed with a spring constant that is at most half of the first spring's spring constant. This parameter change in spring stiffness compensates for the mass increase, maintaining the impact frequency within an acceptable range while achieving higher torque output through increased total mass.
4Force
If the tangential impact mechanism is adapted for resonant operation, then the torque range is limited, but the impact force is maximized within that range
Solution Approach 1:
The system transitions from a fixed resonant operation to a dynamic, adjustable configuration. The additional mass with its softer second spring creates a more compliant hammer assembly that can operate effectively across a broader torque range. This dynamic adaptation allows the mechanism to maintain effective operation beyond the narrow resonant point, increasing versatility while preserving impact force capability.
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 adaptation enables a broader applicable torque range with minimal change in handling torque and motor speed, allowing the tool to be easily switched between operating states, enhancing usability and efficiency.
Implementation Method 1
the additional mass is under the force of a second spring
Implementation Method 2
a tangential impact mechanism of the hand-held power tool—similar to a spring-mass system—can be adapted for resonant operation
Implementation Method 3
Tangential impact mechanisms are usually designed for resonant operation within the framework of a spring-mass system
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The tool has a drive shaft (30) displaced in a rotary and partial tangentially striking motion by a tangential striking mechanism (10). The mechanism is driven by a drive e.g. motor and/or gear. The mechanism includes an anvil (60) associated to the shaft, and a hammer (70) associated to the drive. The anvil and the hammer are movable axially under force application of a spring (81), and tangentially and strikingly under twisting of the anvil and the hammer against each other. An auxiliary mass is coupled to a main mass (71) of the hammer and stands under force application of another spring.