Slewing Control Device for Hybrid Construction Machine
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Solution Overview
Problem
Existing slewing control systems for construction machines are prone to 'slewing-down movement' due to insufficient braking force, especially when on inclined ground, as they do not adequately verify the effectiveness of the mechanical brake before disengaging position holding control.
Innovation Solution
A slewing control device that includes a slewing motor, operation amount detection, speed detection, a mechanical brake, and a control unit that only engages the brake after the slewing speed reaches a predetermined low speed and maintains operation until a measured time period exceeds a reference time, ensuring the brake is effective before stopping the slewing command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If position holding control is finished without verifying brake effectiveness, then control responsiveness is improved, but slewing-down movement occurs due to insufficient braking force
Solution Approach 1:
The control unit continuously monitors the slewing speed during position holding control and uses this feedback to determine when to finish the control. Specifically, it finishes position holding control only when the slewing speed becomes equal to or lower than a predetermined speed, ensuring the mechanical brake has sufficient time to become effective and prevent slewing-down movement.
2Loss of time
If mechanical brake is operated at high slewing speed, then stopping time is reduced, but brake wear increases and braking effectiveness decreases
Solution Approach 1:
The control unit performs preliminary action by continuing to output the slewing command to maintain position holding control even after the operation lever is returned to the neutral position. This extended control period allows the slewing speed to naturally decrease to a predetermined low speed before the mechanical brake is operated, ensuring the brake engages at optimal speed conditions to minimize wear and maximize effectiveness.
3Use of energy by moving object
If position holding control is finished early, then energy consumption is reduced, but slewing stability on inclined ground deteriorates
Solution Approach 1:
The control unit uses a time-based threshold (reference time period) as a simple, energy-efficient method to determine when to finish position holding control. After the mechanical brake is operated, the control unit continues outputting the slewing command only for a predetermined reference time period, after which it stops. This time-limited approach ensures sufficient braking effectiveness while minimizing energy consumption compared to indefinite control continuation.
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
Prevents slewing-down movement by confirming the braking force is sufficient before disengaging the slewing control, reducing wear on the brake and power consumption while ensuring stability on inclined surfaces.
Implementation Method 1
a mechanical brake configured to mechanically stop and hold the slewing superstructure
Data Source
AI summary
A brake control unit operates a mechanical brake when a slewing operation amount detected by a slewing operation amount detection unit indicates slewing stop and when a slewing speed detected by a slewing speed detection unit is equal to or lower than a predetermined speed. A time measurement unit measures a brake operation time period during which a brake operation detection value detected by a brake operation detection unit exceeds a predetermined threshold. When the mechanical brake is operated and when the brake operation time period measured by the time measurement unit exceeds a predetermined reference time period, a slewing control unit stops outputting a slewing command.