Container Crane Overload Prevention via Sensor-Triggered Braking
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Solution Overview
Problem
Existing container crane systems face challenges in quickly restoring operational readiness after an overload emergency stop, as they often require time-consuming manual intervention and suffer from delayed reaction times to overload conditions, leading to potential damage and extended downtime.
Innovation Solution
The implementation of sensors, such as inclination angle and acceleration sensors, to detect impending overloads, triggering a locking brake on the motor drive shaft and a safety brake on the cable drum to proactively stop the hoist before an overload occurs, along with a hydraulic control system for rapid brake activation and release, allowing for quick restarts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensors are used to detect impending overloads and trigger brakes proactively, then the crane system safety is improved and downtime is reduced, but the device complexity increases due to additional sensors and control systems
Solution Approach 1:
The sensor system detects impending overloads before they occur and triggers the brakes proactively. The control unit receives signals from inclination angle sensors and acceleration sensors, determining whether an impending overload exists and activating the locking brake and safety brake before the overload actually occurs, preventing damage and enabling quick restoration.
Solution Approach 2:
The system continuously monitors crane operations through sensors that provide feedback to the control unit. Inclination angle sensors and acceleration sensors monitor the container's position and movement, and the control unit processes this feedback to detect impending overloads and trigger appropriate brake activation, creating a closed-loop control system.
2Device complexity
If manual intervention is required after overload emergency stop, then the brake system design is simplified, but the loss of time increases due to time-consuming manual restoration
Solution Approach 1:
The system enables automatic restoration of operational readiness without manual intervention. After an emergency stop due to impending overload, the control unit automatically manages the brake release and system restart sequence. The sensor system continuously monitors until the container is in a safe position, then automatically clears the overload condition and restores operational readiness, eliminating time-consuming manual restoration procedures.
3Device complexity
If brakes are triggered only after overload occurs, then the response system is simpler, but the stress on the crane system increases leading to potential damage
Solution Approach 1:
The sensor system detects impending overloads before they occur and triggers the brakes proactively. The control unit receives signals from inclination angle sensors and acceleration sensors, determining whether an impending overload exists and activating the locking brake and safety brake before the overload actually occurs, preventing damage and enabling quick restoration.
Solution Approach 2:
The system applies counter-action in advance by detecting the container's unstable position or excessive acceleration and triggering the brakes before the overload can cause damage. This preliminary anti-action prevents the harmful effect of overload stress on the crane structure, drive train, and hoist ropes.
4Speed
If hydraulic control system is used for rapid brake activation, then the braking response speed is improved, but the use of energy increases due to hydraulic pump operation
Solution Approach 1:
The system uses a hydraulic control unit to activate the locking brake and safety brake rapidly. The hydraulic pump builds up pressure in the hydraulic circuit, and the control unit can quickly release this pressure to activate the brakes when an impending overload is detected. This hydraulic actuation provides much faster brake response compared to purely mechanical or electrical systems.
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 solution enables rapid detection and prevention of overloads, reducing stress on the crane system, minimizing tension in hoist ropes, and enabling quick restoration of operational readiness through electronic control, thus enhancing safety and reducing downtime.
Implementation Method 1
a locking brake (70) on the drive shaft (60) of the drive motor (50)... a safety brake (180) on the cable drum (140)... triggered by the sensor, which stops the flywheel of the motor
Implementation Method 2
along with a hydraulic control system for rapid brake activation and release
Data Source
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AI summary
A method and an apparatus are provided for preventing overload of a lifting mechanism for a container crane installation, comprising two identical lifting mechanisms on either side of a gear mechanism (20), each with a drive motor (50, 50'), of which the drive shaft (60, 60') is connected to a gear-mechanism input shaft (80, 80'), and with a safety brake (180, 180') on a cable drum (140, 140') on an output shaft (120, 120') of the gear mechanism (20), wherein lifting cables (150, 150') guided around the cable drum are connected to a load (160) or to a container-receiving headblock (160), and wherein, when a raised container is being raised and moved, at least one sensor (130, 130') determines an overload or a potential overload and the sensor (130, 130') triggers the safety brake (180, 180') on the cable drums and also a blocking brake (70, 70'), which is provided on the motor-drive shaft (60, 60') and stops the flywheel mass of the motor.