Pneumatic Hammer Mechanism for Reducing Retroactive Force Spikes
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Solution Overview
Problem
Pneumatic impact mechanisms in hand-held power tools exert low force peaks on users due to weak coupling between the exciter and impactor, and initial acceleration phases result in strong retroactive force spikes, which are uncomfortable for users.
Innovation Solution
A hand-held power tool design featuring a hammer mechanism with a pneumatic chamber and an airtight housing, where the pneumatic chamber is connected to an interior space through valves that control pressure equalization, reducing retroactive force peaks by extending the coupling duration of the exciter with the hammer and venting during impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pneumatic chamber is strongly coupled during initial acceleration, then the hammer can be accelerated effectively, but strong retroactive force spikes are generated that discomfort the user
Solution Approach 1:
The pneumatic system is segmented into two separate chambers: a first pneumatic chamber for acceleration and a second pneumatic chamber for damping. This segmentation allows each chamber to perform its specialized function independently - the first chamber provides strong coupling for effective acceleration, while the second chamber provides damping to reduce retroactive force spikes, thereby resolving the contradiction between acceleration capability and user comfort.
2Object-affected harmful factors
If the pneumatic chamber provides weak coupling, then retroactive force peaks are reduced, but the initial acceleration phase becomes less effective
Solution Approach 1:
The system divides the pneumatic coupling into two distinct stages through separate chambers: the first chamber enables strong coupling during the initial acceleration phase to maximize hammer speed, while the second chamber provides weak coupling to minimize retroactive force peaks transmitted to the user. This segmentation resolves the contradiction by providing both strong and weak coupling at different stages of the operation cycle.
3Speed
If the pneumatic chamber volume is small, then the response time is fast, but the duration of coupling is insufficient to reduce force spikes
Solution Approach 1:
The pneumatic system is divided into two chambers with different volume characteristics: the first chamber is optimized for fast response with smaller effective volume during acceleration, while the second chamber provides extended duration coupling for damping retroactive forces. This segmentation allows the system to achieve both fast response time and extended coupling duration simultaneously, resolving the contradiction between speed and duration.
4Device complexity
If a single pneumatic chamber is used, then the structure is simple, but it cannot simultaneously provide strong acceleration coupling and weak retroactive force coupling
Solution Approach 1:
The pneumatic system is segmented into two functionally distinct chambers: the first chamber dedicated to acceleration with strong coupling characteristics, and the second chamber dedicated to damping retroactive forces with weak coupling characteristics. This segmentation enables the system to achieve both strong acceleration coupling and weak retroactive force coupling simultaneously, resolving the contradiction between structural simplicity and dual-function performance.
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 reduces the intensity of force spikes during initial acceleration, providing a more comfortable user experience by allowing the exciter to accelerate the hammer for a longer period, thereby minimizing discomfort and improving operational efficiency.
Implementation Method 1
a pneumatic chamber for coupling the movement of the hammer to the periodic movement of the exciter... The air spring in the form of a pneumatic chamber
Implementation Method 2
during the initial acceleration of the racquet by the exciter in the direction of impact, the air spring is strongly compressed... The exciter generates a pressure fluctuation
Implementation Method 3
The pressure in the pneumatic chamber is increased by the pressure equalization between the interior and the pneumatic chamber when the second valve is opened
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A handheld machine tool is disclosed. The tool has a tool receiving area and a striking mechanism. The striking mechanism contains a striker, an exciter, and a pneumatic chamber. The striker strikes an intermediate striker at the strike point. The exciter is driven between a first dead center at a distance from the strike point and a second dead center in the vicinity of the strike point. A housing, which is encapsulated in an air-tight manner, has an interior which is closed by an exciter end face facing away from the striker. The interior is connected to the pneumatic chamber by a first valve which can be closed by the striker and by a second valve which can be closed by the exciter. The first valve is arranged in the vicinity of the strike point and the second valve is arranged in the vicinity of the first dead center.