Percussive Handheld Tool Pneumatic Chamber Stiffness Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hand-held pneumatic hammer drills and chisels with powerful machines are difficult to control due to excessive stress on the hammer mechanism, leading to challenges in guiding the rotary hammer during operation.
Innovation Solution
A percussive handheld power tool with a tool holder, electric motor, and percussion mechanism featuring a pneumatic chamber with a radial opening, a stationary shut-off valve, and a check valve that adjusts air volume to reduce impact power and increase stiffness, allowing easier attachment to the ground and improved response behavior during chiseling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-powered hammer mechanism is used, then impact power is improved, but control and ease of operation deteriorate
Solution Approach 1:
The pneumatic chamber provides dynamic cushioning that automatically adjusts to operating conditions. During initial contact, the compressible air spring absorbs shock and reduces perceived impact force, making the tool easier to control. During sustained operation, the system maintains full power while the cushioning effect stabilizes the tool against vibrations and recoil
Solution Approach 2:
The pneumatic chamber is pre-filled with compressed air that acts as a cushion before impact occurs. This beforehand cushioning reduces the shock transmitted to the user during initial contact and tool engagement, improving control without reducing the actual impact power delivered to the workpiece
2Reliability
If hammer mechanism is deactivated to protect from stress, then reliability is improved, but productivity deteriorates
Solution Approach 1:
The pneumatic chamber is pre-configured with compressed air and valve mechanisms that automatically prepare the cushioning system before each impact cycle. This preliminary preparation ensures the hammer mechanism is always protected during operation, allowing continuous high-productivity use without manual intervention to activate protection
3Stability of the object's composition
If check valve increases air volume in pneumatic chamber, then stiffness of air spring is improved, but impact force deteriorates
Solution Approach 1:
The check valve selectively increases air volume in the pneumatic chamber, changing the physical parameters of the air spring. This increases the stiffness and stabilizes the tool during operation, while the controlled nature of the volume increase maintains sufficient impact force for effective chiseling
4Speed
If stationary check valve with low inertia is used, then response speed is improved, but sensitivity to vibrations deteriorates
Solution Approach 1:
The stationary check valve utilizes pneumatic pressure differentials rather than mechanical inertia to control airflow. This pneumatic actuation provides rapid response to pressure changes while the stationary design and low-inertia construction make the valve insensitive to vibrations during chiseling 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 enhances control over the tool by reducing impact power and increasing stiffness, making it easier to attach to the ground and maintain stability during chiseling operations, while also being insensitive to vibrations and having quick response behavior.
Implementation Method 1
A pneumatic chamber creates an air spring that couples a hammer to an exciter driven by the motor
Implementation Method 2
an elastic locking element, wherein the elastic locking element, in a relaxed state, has a basic shape that partially or completely lifts away from the valve seat, and wherein, in the operating position, the elastic locking element is forced into a clamped shape fully against the valve seat by the valve core
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
The invention relates to a striking hand-held tool (1) having a tool holder (2) for holding a striking tool (4) on a working axis (3), an electric motor (8), and a striking mechanism (5). The striking mechanism (5) has an exciter (13) moved by the electric motor (8), a striker (14) coupled to the exciter (13) by means of a pneumatic chamber (16) arranged between the exciter (13) and the striker (14), and a ram (15) arranged in the striking direction (6) of the striker (14). In a working position the ram (15) rests counter to the striking direction (6) against a stop (22). The pneumatic chamber (16) has a radial opening (30). A stationary shut-off valve has a valve seat (34, 43) and an elastic shut-off member (35, 44), wherein the elastic shut-off member (35, 44) in a relaxed state has a basic form which lifts off partially or completely from the valve seat (34, 43), and wherein in the working position the elastic shut-off member (35, 44) is forced by the ram (15) into a tensioned form resting completely against the valve seat (34, 43). The non-return valve (29) is connected on the input side to the stationary shut-off valve (28, 42) and on the output side to the radial opening (30).