Rigidly Coupled Impact Tool Motor Current Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric motor-driven impact tools face limitations due to the risk of current impulses and overheating when using direct coupling between the motor and impact mechanism, as sudden stops or direction reversals can cause excessive current flow, damaging the motor and electronic components.
Innovation Solution
Implementing a control circuit that limits the current supplied to the electric motor by disabling current supply when it exceeds a threshold, using pulse width modulation and current measurement circuits to prevent excessive current, allowing for direct coupling between the electric motor and impact mechanism without risking damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct coupling between electric motor and impact mechanism is implemented, then device complexity is reduced and torque is improved, but current impulses and overheating occur damaging the motor
Solution Approach 1:
The control circuit continuously monitors motor current and provides feedback to adjust power delivery. When current approaches dangerous levels during impact events, the control circuit reduces or interrupts power supply to prevent damage, enabling direct coupling while maintaining motor reliability.
Solution Approach 2:
The control circuit is prepared in advance to detect current anomalies and respond immediately. By having the control system ready to interrupt power supply before excessive current can cause damage, the system enables direct coupling without compromising motor reliability.
2Reliability
If compliant connection between electric motor and impact mechanism is used, then motor reliability is maintained, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical compliant mechanisms (such as ball-and-cam mechanisms or gear systems) with an electrical control solution. The control circuit electronically manages current delivery to protect the motor during impact events, achieving the same protective function with simpler overall system architecture.
3Force
If rigid coupling between electric motor and impact mechanism is implemented, then torque is improved and device complexity is reduced, but current impulses occur causing overheating
Solution Approach 1:
The control circuit monitors current levels in real-time and provides feedback control. When rigid coupling causes current spikes during impact events, the control circuit detects these conditions and adjusts power delivery to prevent excessive current and resulting overheating, enabling high-torque operation safely.
Solution Approach 2:
The control circuit uses periodic pulse width modulation to deliver power to the motor. By controlling the duty cycle of power delivery, the system can provide high average torque while preventing sustained excessive current that would cause overheating during impact events.
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
Enables the use of rigidly coupled electric motor and impact mechanisms, preventing current surges and overheating, thus allowing for more torque and operational flexibility while protecting motor and electronic components.
Implementation Method 1
an electric motor configured to drive rotation of the hammer about the first axis
Implementation Method 2
the hammer being configured to periodically impact the anvil to drive rotation of the anvil about the first axis
Data Source
AI summary
Illustrative embodiments of impact tools with impact mechanisms rigidly coupled to electric motors are disclosed. In at least one illustrative embodiment, an impact tool may comprise an impact mechanism, an electric motor, and a control circuit. The impact mechanism may comprise a hammer and an anvil, the hammer being configured to rotate about a first axis and to periodically impact the anvil to drive rotation of the anvil about the first axis. The electric motor may comprise a rotor that is rigidly coupled to the impact mechanism, the electric motor being configured to drive rotation of the hammer about the first axis. The control circuit may be configured to supply a current to the electric motor and to prevent the current from exceeding a threshold in response to the hammer impacting the anvil.