Hydraulic Load Lowering Control Under Electro-Hydraulic Faults
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Solution Overview
Problem
Electro-hydraulic systems in work machines often experience faults that are difficult to identify or isolate due to their complex nature, posing hazards when attempting to lower or lift loads, especially when faults exist within the system responsible for load management.
Innovation Solution
A system and method for controlled lowering and lifting of loads in work machines, which includes a controller with a first algorithm for operating a first control valve in load lowering operations. When an operational fault is detected, the controller can enter a safe lowering mode, disabling the first algorithm and using pulse width modulation (PWM) current to control the first control valve, allowing an operator to control the PWM duty ratio for safe load management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If automated diagnostic procedures are executed to isolate faults in electro-hydraulic systems, then fault identification capability is improved, but system safety deteriorates when actuators are not in safe states
Solution Approach 1:
The system performs preliminary safety verification by checking actuator states before allowing automated diagnostic procedures to execute. This ensures that loads are properly supported and actuators are in safe states prior to fault isolation attempts, preventing dangerous situations while enabling comprehensive diagnostics.
Solution Approach 2:
A safety monitoring layer is introduced as an intermediary between the automated diagnostic system and the physical actuators. This intermediary verifies actuator states and controls procedure execution, allowing fault identification while maintaining safety through intermediate verification steps.
2Device complexity
If normal operating algorithms are used to place the work machine in a safe state, then system simplicity is maintained, but safety deteriorates when faults exist in the load lowering system
Solution Approach 1:
The system changes operational parameters by switching between normal operating mode and safe mode. In safe mode, alternative control algorithms are activated that bypass potentially faulty load lowering systems, using different operational parameters to achieve safe state transitions even when primary systems are compromised.
Solution Approach 2:
The system prepares backup control algorithms and safe modes in advance that can be activated when faults are detected. This cushioning approach ensures that alternative safe operating procedures are already in place before normal systems fail, allowing transition to protected operational states without complete system shutdown.
3Measurement precision
If automated control algorithms are used for load management, then operational precision is improved, but ease of operation deteriorates when faults prevent reliable algorithm execution
Solution Approach 1:
The control system dynamically adapts its operation mode based on detected fault conditions. When faults are present, the system transitions from fully automated precise control to a hybrid mode where automated algorithms provide guidance but operator control is enhanced and simplified, allowing flexible adaptation to varying operational conditions and system states.
Solution Approach 2:
The system continuously monitors operational status and provides feedback to both the control algorithms and the operator interface. When faults are detected, feedback mechanisms adjust the control mode and provide clear operator guidance, maintaining precision through continuous monitoring while simplifying operator interaction through adaptive interface responses.
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
Enables safe and controlled lowering and lifting of loads even with known faults in the system, reducing the risk of accidents by allowing direct operator control of the load movement without relying on potentially faulty system components.
Implementation Method 1
a pulse width modulation (PWM) current is sent from the controller to the first control valve
Data Source
AI summary
A system and method for the controlled lowering and lifting of a load are disclosed. The system and method may include operating a work machine having a hydraulic system including a hydraulic actuator for supporting a load, a first control valve in fluid communication with the actuator, and a controller for operating the first control valve. In one embodiment, the controller includes a first algorithm for operating the first control valve in a load lowering operation. When an operational fault within the hydraulic system is detected, the controller can be configured to enter into a safe lowering mode. In the safe lowering mode, the first algorithm is disabled and a pulse width modulation (PWM) current is sent from the controller to the first control valve. A user interface is provided to allow an operator to control the PWM current duty ratio to allow the load supported by the actuator to be lowered.