Closed-Center Hydraulic Valve Control With Pressure Feedback
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Solution Overview
Problem
Closed-center valve systems lack load-dependent feedback, which is typically provided by open-center systems, making it difficult to mimic the 'feel' of load pressure in closed-center systems, especially in applications where load pressure variations require adjustments in actuator speed, such as in mining or drilling operations.
Innovation Solution
Incorporating a pressure sensor to sense load pressure and modify the operator flow command using a pressure-based flow command, which reduces the flow rate based on sensed pressure, allowing for a customizable 'feel' and power management by converting operator demands into power commands, and using electronic controllers with electro-actuators to adjust valve spool positions in closed-center valve devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If closed-center valve devices are used to maintain system efficiency, then energy loss is reduced, but load-dependent feedback is lost
Solution Approach 1:
The patent introduces a pressure sensor that detects load pressure and feeds this information back to an electronic controller. The controller then adjusts the flow command based on the sensed pressure, recreating the load-dependent feedback mechanism that was inherently present in open-center systems but absent in closed-center systems. This resolves the contradiction by maintaining the energy efficiency of closed-center valves while restoring the load feedback capability through electronic sensing and control.
2Ease of operation
If open-center valve devices are used to provide load-dependent feel, then operator feedback is improved, but energy efficiency deteriorates
Solution Approach 1:
The patent replaces the mechanical load-dependent flow control mechanism of open-center valves with an electronic control system. The electronic controller uses pressure sensor input to dynamically adjust the flow command, substituting the passive mechanical feedback of open-center systems with an active electronic control approach. This achieves the same operator feedback effect while maintaining the energy efficiency of closed-center valve architecture.
3Ease of operation
If pressure-based flow command modification is applied, then load-dependent feel is achieved, but device complexity increases
Solution Approach 1:
The patent introduces a pressure sensor as an intermediary device that bridges the gap between the hydraulic system and the electronic controller. This sensor provides the necessary pressure information to the controller without requiring complex modifications to the valve hardware itself. The intermediary approach allows load-dependent feel to be achieved through software/algorithm processing rather than mechanical complexity, resolving the contradiction by minimizing hardware complexity while achieving the desired operational feedback.
Data Source
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.