Swing Drive Controller Braking Torque Limiting
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Solution Overview
Problem
The existing construction machines face issues with impact due to backlash in the turning mechanism, leading to a rough ride and potential damage, as the gears experience teeth hitting during braking, which degrades ride quality and shortens the machine's service life.
Innovation Solution
A turning drive control unit that employs a control strategy involving relays to short-circuit the turning electric motor, generating a regenerative braking torque, and uses a mechanical brake to smoothly stop the upper-part turning body, thereby minimizing impact and extending the machine's service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electric motor is stopped in a state with a large braking torque, then the stopping time is shortened and productivity is improved, but impact due to backlash of gears occurs and reliability deteriorates
Solution Approach 1:
The control device performs preliminary action by reducing the braking torque before the motor comes to a complete stop. The control device determines when the rotation speed reaches a predetermined threshold and reduces the braking torque at that timing, preventing backlash impact before it occurs. This resolves the contradiction by preparing the system in advance to avoid the harmful effect while maintaining efficient stopping.
2Speed
If the electric motor is stopped with large braking torque, then the stopping speed is improved, but teeth hitting due to backlash occurs and ride quality deteriorates
Solution Approach 1:
The control device reduces braking torque in advance when rotation speed reaches a predetermined value, preventing teeth hitting before it occurs. This preliminary action maintains the ability to achieve fast stopping while eliminating the harmful impact effect that would otherwise occur at lower speeds.
3Power
If the electric motor is stopped with large braking torque, then the braking performance is improved, but the service life of the turning mechanism is shortened
Solution Approach 1:
The control device performs preliminary reduction of braking torque when rotation speed reaches a predetermined threshold, preventing backlash impact before it can damage the gears. This extends the service life of the turning mechanism while maintaining effective braking performance throughout the stopping process.
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 ensures a smooth stop and reduces wear on the turning mechanism, enhancing ride quality and prolonging the service life of the construction machine by effectively managing the braking process.
Implementation Method 1
A turning drive control unit that employs a control strategy involving relays to short-circuit the turning electric motor, generating a regenerative braking torque
Data Source
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AI summary
A turning drive control unit configured to control driving of the rotation mechanism of a construction machine driven to turn by an electric motor includes a drive command generation part configured to generate a drive command driving the electric motor based on the amount of operation input via the operation part of the construction machine; a rotation speed detection part configured to detect the rotation speed of the electric motor; and a drive command generation part configured to generate a drive command driving the electric motor based on a speed command output from the speed command generation part and the rotation speed detected by the rotation speed detection part. At a time immediately before a rotation stop of the electric motor, the braking torque of the electric motor is limited.