Electric Pulse Tool Rotor Speed Control for Defined Torque Pulses
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Solution Overview
Problem
Existing electric pulse tools lack well-defined pulses, leading to variability in the number of pulses required to achieve a target torque, which affects the efficiency and consistency of tightening operations.
Innovation Solution
The electric pulse tool controls the speed of the rotor until a play in the gear arrangement is closed, allowing for a known kinetic energy to be achieved in each pulse, by using a processor to manage current pulses and position sensors to determine the position change of the rotor, ensuring consistent torque delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pulsed current is fed to the electric motor to reduce reaction force, then the reaction force on the operator is reduced, but the pulses become undefined and variable in number
Solution Approach 1:
The patent changes the control parameter from simple pulsed current application to speed-controlled pulsing. By controlling the rotor speed to reach a predetermined value before each pulse and maintaining specific speed ranges during pulse delivery, the system achieves well-defined pulses with consistent kinetic energy while still delivering pulsed torque to reduce reaction force.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the rotor speed and adjusting the current pulses accordingly. The control circuit receives speed information and uses it to determine when to apply current pulses and when to stop them, ensuring that each pulse delivers the intended kinetic energy and that pulses are properly defined and consistent.
2Device complexity
If simple pulsed current control is used, then the device complexity is low, but the manufacturing precision of torque delivery is poor
Solution Approach 1:
The patent replaces simple electrical pulsed control with a speed-based control system. Instead of relying solely on current pulse timing, the system uses speed monitoring and control to define pulse delivery, which provides more precise control over the kinetic energy delivered in each pulse and ensures consistent torque delivery.
3Ease of operation
If pulsed operation is used to reduce reaction force, then operator ergonomics improve, but the number of pulses required to reach target torque varies
Solution Approach 1:
The patent applies preliminary action by ensuring the rotor reaches a predetermined speed before each pulse is delivered. This pre-conditioning of the rotor speed ensures that each pulse starts from the same kinetic energy baseline, making the number of pulses required to reach target torque consistent and predictable, thereby improving productivity while maintaining ergonomic benefits.
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 approach results in more defined pulses, reducing the reaction force on the operator and improving the ergonomic and productivity aspects of handheld tools by achieving a consistent kinetic energy for each pulse, thereby enhancing the precision and efficiency of tightening operations.
Implementation Method 1
a position sensor arranged to determine the position change of the rotor and whereby the speed is determined based on the determined position change of the rotor
Implementation Method 2
an electric motor with a rotor and a gear arrangement adapted to drive the output shaft
Data Source
Figure 1
AI summary
The present disclosure relates to an electric pulse tool (10) and a method in an electric pulse tool (10) to achieve well defined pulses. This object is obtained by an electric pulse tool (10), where torque is delivered in pulses on an output shaft (14) of the electric pulse tool (10). The electric pulse tool (10) comprises an electric motor (11) with a rotor (12) and a gear arrangement (13) adapted to drive the output shaft (14). Whereby the electrical pulse tool (10) for each period is operative to control the speed of the rotor (12) until a play in the gear arrangement (13) is determined to be closed and the gear arrangement starts to move the output shaft