High-Speed Brushless Motor Pneumatic Percussion Chisel
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Solution Overview
Problem
Chiseling hand-held power tools face challenges with gearbox durability due to high loads from impact mechanisms and blocked drills, leading to gear teeth breakage, and existing high-speed electric motors are not effectively optimized for dynamic load changes.
Innovation Solution
A chiseling hand-held power tool with an electric motor operating at speeds greater than 80,000 revolutions per minute, coupled with a high reduction gear ratio and a lightweight, low-inertia rotor, allowing for efficient energy transfer and dynamic response to load changes, using a brushless electric motor with a planetary gear stage and a pneumatic percussion mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a reduction gear is used to adapt motor speed to percussion mechanism strokes, then the speed ratio is achieved, but the gear teeth can break due to high loads from impact mechanisms and blocked drills
Solution Approach 1:
The patent changes the speed parameter by using a high-speed motor (greater than 80,000 rpm) combined with a reduction gear ratio of at least 20:1. This parameter change allows the system to achieve the required speed reduction while the high motor speed enables more efficient energy transfer and dynamic response, reducing the mechanical stress on gear teeth during impact operations
2Reliability
If a robust gearbox is designed to withstand high loads, then gear tooth breakage is prevented, but the device complexity and weight increase
Solution Approach 1:
The patent changes the operational parameters by using a high-speed motor (greater than 80,000 rpm) with a reduction gear ratio of at least 20:1. This allows the gearbox to operate at optimized stress levels where the high motor speed compensates for the reduced gear robustness, enabling lighter gear design while maintaining reliability during impact operations
3Device complexity
If conventional electric motors are used, then the system is simple, but the dynamic response to load changes is insufficient
Solution Approach 1:
The patent changes the motor speed parameter to greater than 80,000 rpm with a reduction gear ratio of at least 20:1. This parameter change enables the motor to respond dynamically to load changes during percussion operations, as the high speed allows for faster acceleration and deceleration cycles while the reduction gear provides the necessary torque multiplication
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 enables optimal efficiency and durability by maintaining high speed and power output while minimizing gear losses and moment of inertia, effectively handling dynamic load changes and ensuring robust operation.
Implementation Method 1
a pneumatic chamber (18) closed off by the exciter piston (12) and the beater (13) for coupling a movement of the beater (13) to the exciter piston (12)
Data Source
Figure 1
AI summary
The invention relates to a chiselling hand-held power tool (1) having a tool holder (2) for holding a tool (3) on a working axis (7), an electric motor (8), and a hammer mechanism (4). The hammer mechanism has an excitation piston (12) coupled to the motor, a hammer (13) guided on the working axis and a pneumatic chamber (18) closed by the excitation piston and the hammer for coupling a movement of the hammer to the excitation piston. The rotational speed of the electric motor corresponds to at least 20 times the blow rate of the hammer mechanism.