Pneumatic Impact Mechanism Mode Switching
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Solution Overview
Problem
Existing electric tools with percussion mechanisms lack an efficient and reliable method to switch between operating modes, such as drilling and chiseling, without mechanically loading the clutch in the power transmission path, which can lead to inefficiencies and wear.
Innovation Solution
A power tool design featuring a pneumatic impact mechanism with a guide tube and valve system that allows for the pneumatic decoupling of the hammer piston from the drive piston, enabling the impact mechanism to be activated or deactivated by rotating a switching sleeve, thus controlling air pressure and impact transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clutch is used in the power transmission path to mechanically separate the motor from the percussion mechanism, then the impact mechanism can be deactivated, but the clutch is subjected to mechanical stresses and wear when the percussion mechanism is engaged
Solution Approach 1:
The patent replaces the mechanical clutch system with a pneumatic coupling system. The drive piston and hammer piston are coupled through a pneumatic chamber filled with compressible gas, allowing the hammer piston to be activated or deactivated by controlling gas pressure rather than through mechanical engagement. This eliminates the mechanical clutch and its associated wear and stress issues.
Solution Approach 2:
The patent uses a pneumatic chamber with compressible gas to couple the drive piston and hammer piston. By controlling the gas pressure in this chamber, the system can smoothly engage or disengage the impact mechanism without mechanical contact, thereby eliminating clutch wear and improving reliability.
2Productivity
If a mechanical clutch is used to switch between operating modes, then the impact mechanism can be deactivated, but this leads to mechanical wear and inefficiencies
Solution Approach 1:
The patent replaces the mechanical clutch system with a pneumatic coupling system. The drive piston and hammer piston are coupled through a pneumatic chamber filled with compressible gas, allowing the hammer piston to be activated or deactivated by controlling gas pressure rather than through mechanical engagement. This eliminates the mechanical clutch and its associated wear and stress issues.
Solution Approach 2:
The patent uses a pneumatic chamber with compressible gas to couple the drive piston and hammer piston. By controlling the gas pressure in this chamber, the system can smoothly engage or disengage the impact mechanism without mechanical contact, thereby eliminating clutch wear and improving reliability.
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 solution allows for seamless switching between operating modes without mechanically loading the clutch, enhancing efficiency and reducing wear, while ensuring the impact mechanism is automatically activated or deactivated based on the selected mode, simplifying operation.
Implementation Method 1
a pneumatic chamber (27) formed between a drive piston (26) and a hammer piston (28) in the guide tube (25), for pneumatically coupling movements of the drive piston (26) with movements of the hammer piston (28)
Implementation Method 2
A valve has an inlet opening formed within the guide tube in the pneumatic chamber and an outlet opening formed outside the guide tube... In the first operating mode, the switching sleeve interrupts an air path between the inlet and outlet openings to close the valve. In the second operating mode, the switching sleeve is rotated by an angle α relative to the first operating mode... and the switching sleeve, via a switching sleeve feedthrough, releases the air path between the inlet and outlet openings to open the valve.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
Power tool (1), in particular rotary hammer or cordless rotary hammer, with housing (3), motor (9) and pneumatic impact mechanism comprising a guide tube (25), a drive piston (26), a hammer piston (28) and a pneumatic chamber (27). The guide tube (25) is rotatably mounted in a switching sleeve (45), and the switching sleeve (45) is rotatably mounted in a bearing device (49). A valve (38) has an inlet opening (39) inside the guide tube in the pneumatic chamber (27), and an outlet opening (40) outside the guide tube. In a first operating mode setting (17/18/19), the valve (38) is closed, preventing air exchange between the inlet opening (39) and the outlet opening (40) and activating an impact mechanism. The valve (38) is open in the second operating mode setting (17 / 18 / 19), allowing air exchange between the inlet opening (39) and the outlet opening (40) and deactivating the impact mechanism.In the first operating mode setting (17 / 18 / 19), the switching sleeve (45) interrupts an air path between the inlet opening (39) and the outlet opening (40). In the second operating mode setting (17 / 18 / 19), the switching sleeve (45) is rotated by an angle (a) relative to the first operating mode setting (17, 18, 19) in the housing-fixed bearing device (49), and the switching sleeve (45) opens the air path between the inlet opening (39) and the outlet opening (40) via a switching sleeve guide (46).