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A method for calibrating a valve having a valve element movable between a flow blocking position and a flow passing position includes pressurizing fluid directed to the valve, increasing a current directed to the valve for controlling a position of the valve element, and sensing a pressure of the fl

A method for calibrating a valve having a valve element movable between a flow blocking position and a flow passing position includes pressurizing fluid directed to the valve, increasing a current directed to the valve for controlling a position of the valve element, and sensing a pressure of the fluid. The method for calibrating the valve also includes determining if a time-derivative of the sensed fluid pressure is greater than a predetermined threshold over a predetermined period of time, and determining a cracking point current command directed to the valve. The cracking point current command is directed to the valve when the time-derivative of the sensed fluid pressure is greater than the predetermined threshold.

대표청구항 ▼

What is claimed is: 1. A method for calibrating a valve, the valve having a valve element movable between a flow blocking position and a flow passing position, the method comprising: pressurizing fluid directed to the valve; increasing a current directed to the valve for controlling a position of t

What is claimed is: 1. A method for calibrating a valve, the valve having a valve element movable between a flow blocking position and a flow passing position, the method comprising: pressurizing fluid directed to the valve; increasing a current directed to the valve for controlling a position of the valve element; sensing a pressure of the fluid; determining if a time-derivative of the sensed fluid pressure is greater than a predetermined threshold over a predetermined period of time; and determining a cracking point current command directed to the valve, the cracking point current command being directed to the valve when the time-derivative of the sensed fluid pressure is greater than the predetermined threshold. 2. The method of claim 1, further including determining a calibration offset current command based on a difference between an expected cracking point current command and the determined cracking point current command. 3. The method of claim 2, further including determining an actual current command to direct to the valve based on the determined calibration offset current command and a nominal current command. 4. The method of claim 3, wherein the actual current command is based on a summation of the determined calibration offset current command and the nominal current command. 5. The method of claim 4, wherein the nominal current command is based on a desired position of the valve element. 6. The method of claim 1, wherein: the fluid is pressurized at a source; and the fluid pressure is sensed at an outlet of the source. 7. The method of claim 1, wherein the determined cracking point current command is directed to the valve when the time-derivative of the sensed fluid pressure begins to be greater than the predetermined threshold. 8. The method of claim 1, wherein: the valve is one of a first valve and a second valve; the first valve is configured to control fluid flow to a chamber of an actuator; and the second valve is configured to control fluid flow from the chamber of the actuator. 9. The method of claim 8, wherein: the fluid is pressurized at a source; and the fluid pressure is sensed at an outlet of the source upstream of the first and second valves. 10. The method of claim 1, further including: determining and storing a plurality of the cracking point current commands; and determining if a maximum deviation between the cracking point current commands is below a predetermined threshold. 11. The method of claim 1, further including: determining multiple calibration offset current commands for the same valve; and determining if a maximum deviation between the multiple calibration offset commands is below a predetermined threshold. 12. A system for calibrating a valve, the valve having a valve element movable between a flow blocking position and a flow passing position, the system comprising: a source configured to pressurize a fluid; a pressure sensor configured to sense a pressure of the fluid at an outlet of the source; and a controller connected to the pressure sensor, the controller being configured to: increase a current directed to the valve for controlling a position of the valve element; receive a sensed fluid pressure from the pressure sensor; determine if the valve is at the flow passing position based on the measured fluid pressure at the outlet of the source; and determine a cracking point current command directed to the valve when the valve is at the flow passing position. 13. The system of claim 12, wherein the controller is further configured to determine a calibration offset current command based on a difference between an expected cracking point current command and the determined cracking point current command. 14. The system of claim 13, wherein the controller is further configured to determine an actual current command to direct to the valve based on a summation of the determined calibration offset current command and a nominal current command. 15. The system of claim 14, wherein the nominal current command is based on a desired position of the valve element. 16. A method for determining an actual current command to control a valve, the valve having a valve element movable between a flow blocking position and a flow passing position, the method comprising: determining a nominal current command based on a desired position of the valve element; determining a calibration offset current command based on a calibration of the valve; and determining the actual current command by summing the nominal current command and the calibration offset current command. 17. The method of claim 16, wherein the calibration offset current command is based on a difference between an expected cracking point current command and a cracking point current command determined from the calibration of the valve. 18. The method of claim 16, wherein the calibration of the valve includes: pressurizing fluid directed to the valve at a source; increasing a current directed to the valve for controlling a position of the valve element; sensing a pressure of the fluid at an outlet of the source; determining if the valve is at a flow passing position based on the sensed fluid pressure; and determining a cracking point current command directed to the valve when the valve is at the flow passing position. 19. The system of claim 12, wherein the controller is further configured to determine if a time-derivative of the sensed fluid pressure is greater than a predetermined threshold for a predetermined period of time, the determined cracking point current command being directed to the valve when the time-derivative of the sensed fluid pressure begins to be above the predetermined threshold. 20. The method of claim 16, wherein the calibration of the valve includes: pressurizing fluid directed to the valve; increasing a current directed to the valve for controlling a position of the valve element; sensing a pressure of the fluid; determining if a time-derivative of the sensed fluid pressure is greater than a predetermined threshold over a predetermined period of time; and determining a cracking point current command directed to the valve, the cracking point current command being directed to the valve when the time-derivative of the sensed fluid pressure begins to be greater than the predetermined threshold. 21. The method of claim 16, wherein the nominal current command is associated with a nominal control curve, and the determining of the actual current command includes shifting the nominal control curve based on the calibration offset current command. 22. The method of claim 21, further including determining an actual control curve based on the shifting of the nominal control curve. 23. The method of claim 16, further including determining an actual control curve associated with the actual current command. 24. The method of claim 23, wherein the actual control curve is based on a nominal control curve and the calibration offset current command, and the nominal control curve is associated with the nominal current command.