Closed-Center Hydraulic Flow Control With Pressure-Based Load Feel
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Solution Overview
Problem
Closed-center valve systems lack the load-dependent 'feel' typically associated with open-center valve systems, which provides visual feedback on load pressure through actuator speed changes, and they are not efficient in applications requiring load-dependent control.
Innovation Solution
A load-dependent flow control system using pressure sensors to modify operator flow commands based on sensed load pressure, reducing flow rates at higher pressures, and incorporating electronic controllers to adjust valve spool positions and flow rates, mimicking the load-dependent feel of open-center systems while maintaining closed-center efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If closed-center valve systems are used, then system efficiency is improved, but load-dependent feel is lost
Solution Approach 1:
The system incorporates pressure sensors that detect load pressure and provide feedback to the electronic controller. The controller then adjusts the valve spool position to modify flow rates based on the sensed pressure, creating a load-dependent response that mimics the feel of open-center systems while maintaining closed-center efficiency.
Solution Approach 2:
The patent replaces the mechanical flow diversion mechanism of open-center valves with an electronically controlled system. The electronic controller processes pressure sensor signals and actuates the valve spool accordingly, substituting mechanical feedback with electronic sensing and control to achieve the same operational feel.
2Ease of operation
If open-center valve systems are used, then load-dependent feel is provided, but system efficiency deteriorates
Solution Approach 1:
The patent replaces the inherently inefficient open-center mechanical flow diversion with an electronically controlled closed-center valve system. The electronic controller mimics the load-dependent behavior of open-center systems by adjusting valve spool position based on pressure sensor feedback, achieving the desired operational feel without the energy loss of continuous flow diversion.
Solution Approach 2:
Pressure sensors provide real-time feedback on load conditions to the electronic controller, which then adjusts the valve spool position to create load-dependent flow control. This feedback loop replicates the operational characteristics of open-center systems while maintaining the energy efficiency of closed-center architecture.
3Reliability
If flow rates are reduced at high pressures, then equipment protection is improved, but actuator speed decreases
Solution Approach 1:
The system dynamically adjusts the valve spool position based on real-time pressure sensor feedback. At high pressures, the electronic controller modifies the spool position to reduce flow rates, protecting equipment from overload. At normal pressures, full flow rates are maintained for optimal actuator speed, creating a dynamic response that adapts to operating conditions.
Solution Approach 2:
The electronic controller changes the flow rate parameter in response to pressure conditions. When pressure exceeds thresholds indicating high-load conditions, the controller reduces the flow rate to protect equipment. When pressure is within normal ranges, the controller maintains higher flow rates for faster actuator operation, dynamically adjusting parameters based on system state.
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 system provides a customizable 'feel' for operators and machines, reduces power demand, and protects equipment by slowing down actuators in high-load conditions, enhancing operational efficiency and safety in applications like mining.
Implementation Method 1
A pressure sensor is provided for sensing a pressure of the hydraulic fluid provided to the hydraulic actuator
Implementation Method 2
The closed-center valve device includes a valve spool and an electro-actuator that adjusts a position of the valve spool to adjust a rate of the hydraulic fluid flow supplied to the hydraulic actuator
Implementation Method 3
A hydraulic pump provides pressurized hydraulic fluid to power one or more hydraulic actuators
Data Source
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AI summary
The present disclosure relates to a load dependent flow control system for directing hydraulic fluid to a hydraulic actuator. The load dependent flow control system includes a closed-center valve device for controlling hydraulic fluid flow to the actuator. The closed-center valve device includes a valve spool and an electro-actuator that adjusts a position of the valve spool to adjust a rate of the hydraulic fluid flow supplied to the hydraulic actuator. A pressure sensor is provided for sensing a pressure of the hydraulic fluid provided to the hydraulic actuator. The system also includes an electronic controller configured to receive an operator flow command from an operator interface. The operator flow command corresponds to a base flow through the closed-center valve device. The electronic controller interfaces with the electro-actuator of the closed-center valve device and with the pressure sensor. At least when the sensed pressure is above a threshold pressure, the electronic controller uses the operator flow command and the sensed pressure to generate a pressure-modified flow command that is sent to the closed-center valve device to control flow through the closed-center valve device. The pressure-modified flow command corresponds to a pressure-modified flow through the closed-center valve device. The pressure-modified flow is less than the base flow through the closed-center valve device.