Electric Motor Impact Tool with Direction Sensor Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric motors are not considered feasible for use in impact tools with Maurer mechanisms due to high current draw and heat issues during rapid rotation reversals, unlike air motors which experience negligible wear.
Innovation Solution
An electric impact tool design incorporating a direction sensor and controller to manage the electric motor's operation, disabling forward mode during reverse rotation and enabling it only when the rotating mass is not reversing, with an optional energy storing mechanism to absorb and release energy for efficient forward rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an electric motor is used in an impact tool with a Maurer mechanism, then the tool can deliver high torque through impact loading, but the motor experiences high current draw and heat issues during rapid rotation reversals
Solution Approach 1:
The controller disables the motor before the hammer rebounds and reverses direction, preventing the motor from operating during the harmful reverse rotation phase. This preliminary action avoids the high current draw and heat generation that would occur if the motor tried to control the rapid reversal, while still allowing the hammer to deliver full impact torque to the anvil during the forward strike phase
2Power
If an electric motor is used in an impact tool with a Maurer mechanism, then the tool can deliver high torque through impact loading, but the motor experiences damaging heat under conditions in which the output shaft is rotated opposite the forward direction
Solution Approach 1:
The controller disables the motor before the hammer rebounds and reverses direction, preventing the motor from operating during the harmful reverse rotation phase. This preliminary action avoids the high current draw and heat generation that would occur if the motor tried to control the rapid reversal, while still allowing the hammer to deliver full impact torque to the anvil during the forward strike phase
3Ease of operation
If the motor is kept energized during hammer rebound, then the motor can maintain control, but high current draw occurs during reverse rotation
Solution Approach 1:
The controller disables the motor before the hammer rebounds and reverses direction, preventing the motor from operating during the harmful reverse rotation phase. This preliminary action avoids the high current draw and heat generation that would occur if the motor tried to control the rapid reversal, while still allowing the hammer to deliver full impact torque to the anvil during the forward strike phase
Solution Approach 2:
The controller monitors the hammer's motion and detects when reverse rotation begins, then disables the motor in response. This feedback mechanism ensures the motor is only operating during the useful forward strike phase, avoiding unnecessary energy consumption during the rebound phase while maintaining precise control when needed
Data Source
Figure 1
Figure 2a~2f
Figure 2g~2l
AI summary
An electric impact tool (210) in which a rotating mass rotates in a forward direction (201) to impact upon and transfer torque to an anvil (135), and rotates in a reverse direction opposite the forward direction (202) in response to such impact. A direction sensor (355,360) monitors the direction of rotation of the rotating mass, and a controller (370) turns an electric motor (255) on and off during respective forward and reverse rotation of the rotating mass. An energy storing mechanism (275,280) may be used to absorb energy from reverse rotation of the rotating mass and release the absorbed energy to rotate the rotating mass in the forward direction. A controller (370) may be used to store the angular position of the rotating mass upon each impact and turn off the motor (255) prior to the following impact to avoid energizing the motor during stall.