Asymmetrical Spring Stiffness Vibration Damper for Handheld Power Tools
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Solution Overview
Problem
Handheld power tools with existing vibration dampers fail to effectively reduce user discomfort due to periodic return blows, as they often result in non-harmonious movements and forces that are not adequately damped, leading to increased physiological burden on the user.
Innovation Solution
A vibration damper with a mass element suspended in a spring mechanism having asymmetrical spring stiffness, where the first spring stiffness is five to ten times greater than the second, allowing for adjusted damping and rebound behavior, and featuring a mass element connected to prestressed springs and a bending spring, which reduces energy transfer and minimizes losses through plastic deformation or friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional vibration damper with symmetrical spring stiffness is used, then the structure is simple and easy to manufacture, but it fails to effectively dampen periodic return blows and creates non-harmonious movements that increase user discomfort
Solution Approach 1:
The patent applies asymmetry by configuring the spring mechanism with different spring stiffness values in opposite directions. Specifically, the spring mechanism has a first spring stiffness in a first direction and a second spring stiffness in a second direction opposite to the first direction, where the first spring stiffness differs from the second spring stiffness. This asymmetrical design allows the vibration damper to effectively counteract periodic return blows by providing different resistance characteristics for different directions of motion, thereby reducing non-harmonious movements and user discomfort.
Solution Approach 2:
The patent applies local quality by making specific parts of the spring mechanism have different properties. The spring mechanism is designed with localized variations in stiffness characteristics - the first spring stiffness and second spring stiffness are deliberately made different to address specific damping requirements in different directions. This allows targeted optimization of damping performance in the direction where return blows occur most frequently.
2Reliability
If the spring stiffness is made asymmetrical with a ratio of five to ten times, then the damping effect is significantly enhanced, but the spring mechanism becomes more complex and difficult to manufacture
Solution Approach 1:
The patent applies parameter changes by deliberately varying the spring stiffness parameters in different directions. The first spring stiffness is set to be five to ten times the second spring stiffness, creating a controlled asymmetry that optimizes damping effectiveness. This parameter variation allows the system to achieve superior damping performance while maintaining manufacturability through standardized spring design approaches and reasonable stiffness ratios.
3Loss of energy
If the mass element is connected to prestressed springs with fixed connection, then energy losses due to plastic deformation and friction are reduced, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-stressing the springs before they are put into service. The mass element is arranged between two prestressed springs that are fixedly connected to it. This preliminary pre-stressing ensures that the springs are always under tension, preventing slack and eliminating energy losses due to plastic deformation and friction that would occur with loose connections. The fixed connection design maintains constant contact between springs and mass element throughout operation.
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 solution significantly reduces user discomfort by enhancing the damping effect, providing a more harmonious movement and force distribution, thereby reducing the physiological burden on the user during operation.
Implementation Method 1
The vibration damper has a mass element suspended in a spring mechanism. The spring mechanism acts in a first direction parallel to the working axis with a first spring stiffness and it acts with a second spring stiffness in a second direction opposite the first direction.
Implementation Method 2
The mass element in the basic position is in contact with the spring. In the basic position the mass element may be arranged between two prestressed springs.
Implementation Method 3
Because of the fixed connection, this results in low losses in the springs due to plastic deformation or due to friction.
Implementation Method 4
Because of the fixed connection, this results in low losses in the springs due to plastic deformation or due to friction.
Data Source
AI summary
A handheld power tool is disclosed. The handheld power tool has a drive oscillating along a working axis and a vibration damper. The vibration damper has a mass element suspended in a spring mechanism. The spring mechanism acts with a first spring stiffness and acts with a second spring stiffness. The first spring stiffness is different from the second spring stiffness.