Load-Sense Hydraulic Actuator Stall Detection by Pressure Margin
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Solution Overview
Problem
Existing hydraulic systems lack the ability to effectively detect and respond to deadhead or stall conditions in load sense hydraulic systems, which occur when actuators reach their end stops or encounter loads exceeding system pressure capabilities.
Innovation Solution
A hydraulic system incorporating a hydraulic actuator, metering valves, a variable displacement pump, pressure sensors, and an electronic controller to monitor pressure margins and generate indications of deadhead or stall conditions, adjusting operational parameters to remedy these situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors and monitoring systems are added to detect deadhead or stall conditions, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the load sense margin (pressure difference between pump output and actuator load) and using this information to detect deadhead or stall conditions. The electronic controller receives pressure sensor signals, compares the actual load sense margin against expected margins during flow commands, and generates detections based on deviations. This feedback mechanism enables accurate detection without requiring complex additional hardware beyond standard load sense hydraulic components and basic pressure sensing.
2Reliability
If the system continuously monitors pressure margins and flow commands, then reliability of deadhead or stall detection is improved, but energy consumption increases
Solution Approach 1:
The electronic controller performs deadhead or stall detection periodically by checking specific conditions only when flow commands are active. The controller monitors whether a flow command is being issued to an actuator, and only then evaluates the pressure margin conditions to detect deadhead or stall. This periodic monitoring approach, triggered by flow command events rather than continuous operation, maintains high detection reliability while significantly reducing the energy consumption of the electronic controller compared to continuous monitoring.
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 accurate detection and management of deadhead or stall conditions, enhancing system efficiency and productivity by reallocating flow to other actuators and maintaining optimal pressure margins.
Implementation Method 1
The electronic controller monitors hydraulic pressure in the hydraulic system via the pressure sensors
Implementation Method 2
the variable displacement hydraulic pump operating to maintain a normal operating pressure margin above the actuator load pressure enabling flow to the hydraulic actuator
Implementation Method 3
The metering valve is for metering flow in and out of the hydraulic actuator
Data Source
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Figure 2
AI summary
A load sense hydraulic system includes pressure sensors that provide feedback to an electronic controller to monitor a pressure margin between a pump supply pressure and an actuator meter-in load pressure. Pre-collapse and collapse of the pressure margin (the collapse indicating a deadhead or stall condition of the actuator), can be tracked by the electronic controller to establish a normal operating pressure margin. The established normal operating pressure margin can be assessed by the controller against a current, actual pressure margin based on feedback from the pressure sensors. A pre-determined threshold variation by the actual pressure margin from the normal operating pressure margin provides an indication of deadhead or stall condition to the controller. The controller may then responsively make modifications to the load sense hydraulic system to remedy the deadhead/stall condition.