Claims
- 1. A method of measuring at least one of position, velocity, and acceleration of a piston slidably contained within a hydraulic cylinder of a hydraulic actuator, the method comprising:
(a) measuring a differential pressure across a discontinuity positioned in hydraulic fluid flow traveling into and out of a first cavity which is defined by the piston and the hydraulic cylinder; (b) calculating a flow rate of the hydraulic fluid flow into and out of the first cavity as a function of the differential pressure; and (c) calculating at least one of position, velocity, and acceleration of the piston as a function of the flow rate.
- 2. The method of claim 1, including a step (d) of producing an output signal that is indicative of at least one of the position, the velocity, and the acceleration of the piston within the hydraulic cylinder.
- 3. The method of claim 1, including a step of measuring a temperature of the hydraulic fluid.
- 4. The method of claim 3, wherein the flow rate is further calculated as a function of the temperature of the hydraulic fluid in the calculating step (b).
- 5. The method of claim 1, wherein the measuring step (a) includes subtracting a first measured static pressure from a second measured static pressure, wherein the first and second measured static pressures are located on opposite sides of the discontinuity.
- 6. A device for measuring at least one of position, velocity, and acceleration of a piston slidably contained within a hydraulic cylinder of a hydraulic actuator, the device comprising:
a differential pressure flow sensor positioned inline with a hydraulic fluid flow and adapted to measure a pressure drop across a discontinuity positioned in the hydraulic fluid flow, the differential pressure flow sensor having a first signal, based upon the pressure drop, which is indicative of a flow rate of the hydraulic fluid flow traveling into and out of a first cavity defined by the piston and the hydraulic cylinder; and a calculation module adapted to receive the first signal and responsively provide a second signal, which is indicative of at least one of the position, the velocity, and the acceleration of the piston.
- 7. The device of claim 6, wherein the first signal relates to a parameter that is selected from a group consisting of the pressure drop, the flow rate of the hydraulic fluid flow, and a compensated flow rate of the hydraulic fluid flow.
- 8. The device of claim 6, wherein the differential pressure flow sensor includes:
a flow restriction member positioned within the hydraulic fluid flow and adapted to produce a pressure drop; and a differential pressure sensor configured to measure the pressure drop and responsively produce a differential pressure signal, wherein the first signal is based upon the differential pressure signal.
- 9. The device of claim 6, wherein the differential pressure flow sensor is a bi-directional differential pressure flow sensor, wherein the first signal is further indicative of a direction of the hydraulic fluid flow.
- 10. The device of claim 8, wherein the flow restriction member is a bi-directional flow restriction member.
- 11. The device of claim 8, wherein the differential pressure sensor is embedded in the flow restriction member.
- 12. The device of claim 8, wherein the differential pressure flow sensor further includes processing electronics adapted receive the differential pressure signal and produce the first signal as a function of the differential pressure signal.
- 13. The device of claim 6, wherein the first signal is produced in accordance with a communication protocol selected from a group consisting of an analog communication protocol, a digital communication protocol, and a wireless communication protocol.
- 14. The device of claim 6, further comprising:
a temperature sensor adapted to produce a temperature signal that is indicative of a temperature of the hydraulic fluid; and the second signal is further a function of the temperature signal.
- 15. The device of claim 6, wherein the calculation module includes:
an analog-to-digital (A/D) converter adapted to receive the first signal and convert the first signal into a digitized signal; and a microprocessor electrically coupled to the A/D converter and adapted to receive the digitized flow rate signal and produce the second signal as a function of the digitized signal.
- 16. The device of claim 8, wherein:
the differential pressure sensor includes first and second pressure sensors which respectively produce first and second pressure signals relating to pressures at first and second sides of the flow restriction member; and the differential pressure signal is related to the difference between the first and second pressure signals.
- 17. The device of claim 10, wherein the first signal is further indicative of a direction of the hydraulic fluid flow.
- 18. The device of claim 6, further comprising:
a valve body having a valve port inline with the first cavity through which the hydraulic fluid flow travels; wherein
the differential pressure flow sensor is positioned proximate the valve port.
- 19. The device of claim 18, wherein the differential pressure flow sensor includes a flow restriction member positioned within the hydraulic fluid and includes first and second flow restriction portions.
- 20. The device of claim 19, wherein at least one of the flow restriction portions is integral with the valve body.
- 21. The device of claim 6, wherein the calculating module is further adapted to filter transient portions of the first signal relating to anomalies of the hydraulic fluid flow.
- 22. A hydraulic system comprising:
a hydraulic cylinder having a port coupled to a hydraulic fluid flow; a piston slidably received in the hydraulic cylinder, wherein the hydraulic fluid flow is in fluid communication with a first cavity, defined by the piston and the hydraulic cylinder, through the port; a valve including a valve body and a valve port that is fluidically coupled to the port of the hydraulic cylinder, wherein the hydraulic fluid flow travels through the valve port into and out of the hydraulic cylinder; a differential pressure flow sensor positioned for measurement of the hydraulic fluid flow flowing into and out of the hydraulic cylinder and having a first signal which is indicative a flow rate of the hydraulic fluid into or out of the first cavity; and a calculation module adapted to receive the first signal and responsively provide a second signal, as a function of the first signal, which is indicative of at least one of the position, the velocity, and the acceleration of the piston.
- 23. The system of claim 22, wherein the first signal relates to a parameter that is selected from a group consisting of a differential pressure corresponding to a pressure drop across a discontinuity positioned within the hydraulic fluid flow, the flow rate of the hydraulic fluid flow, a mass flow rate of the hydraulic fluid flow, and a volume flow rate of the hydraulic fluid flow.
- 24. The system of claim 22, wherein the differential pressure flow sensor includes:
a flow restriction member positioned within the hydraulic fluid flow and adapted to produce a pressure drop; and a differential pressure sensor configured to measure the pressure drop and responsively produce a differential pressure signal, wherein the first signal is based upon the differential pressure signal.
- 25. The system of claim 22, wherein the differential pressure flow sensor is a bi-directional differential pressure flow sensor, wherein the first signal is further indicative of a direction of the hydraulic fluid flow.
- 26. The system of claim 24, wherein the differential pressure flow sensor further includes processing electronics adapted receive the differential pressure signal and produce the first signal as a function of the differential pressure signal.
- 27. The system of claim 22, wherein the first signal is produced in accordance with a communication protocol selected from a group consisting of an analog communication protocol, a digital communication protocol, and a wireless communication protocol.
- 28. The system of claim 22, further comprising:
a temperature sensor adapted to produce a temperature signal that is indicative of a temperature of the hydraulic fluid; and the second signal is further a function of the temperature signal.
- 29. The system of claim 22, wherein the calculation module includes:
an analog-to-digital (A/D) converter adapted to receive the first signal and convert the first signal into a digitized signal; and a microprocessor electrically coupled to the A/D converter and adapted to receive the digitized flow rate signal and produce the second signal as a function of the digitized signal.
- 30. The system of claim 22, wherein the differential pressure flow sensor is coupled to the valve port.
- 31. The system of claim 30, wherein the differential pressure flow sensor includes a flow restriction member positioned within the hydraulic fluid and includes first and second flow restriction portions; and wherein at least one of the flow restriction portions is integral with the valve body.
- 32. The system of claim 22, wherein the calculating module is further adapted to filter transient portions of the first signal relating to anomalies of the hydraulic fluid flow.
- 33. A hydraulic system comprising:
a plurality of hydraulic cylinders, each cylinder having a position therein and having a cylinder cavity defined by a cylinder wall and the piston, the cylinder cavity fluidically coupled to a fluid port; a source of hydraulic fluid operably coupled to the fluid port of each of the plurality of hydraulic cylinders; valving interposed between the source of hydraulic fluid and each hydraulic cylinder; a plurality of differential pressure flow sensors positioned for measurement of hydraulic fluid flow flowing into and out of each cylinder cavity of the plurality of hydraulic cylinders; and a calculation module adapted to receive a signal from each differential pressure flow sensor and responsively provide an output signal based upon at least one of the position, the velocity and the acceleration of at least one of the plurality of hydraulic cylinders.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present invention claims the benefit of U.S. patent application Ser. No. 09/521,132, entitled “PISTON POSITION MEASURING DEVICE,” filed Mar. 8, 2000, and U.S. Provisional Application No. 60/218,329, entitled “HYDRAULIC VALVE BODY WITH DIFFERENTIAL PRESSURE FLOW MEASUREMENT,” filed Jul. 14, 2000. In addition, the present invention claims the benefit of U.S. patent application Ser. Nos. 09/521,537, entitled “BI-DIRECTIONAL DIFFERENTIAL PRESSURE FLOW SENSOR,” filed Mar. 8, 2000 and 60/187,849, entitled “SYSTEM FOR CONTROLLING MULTIPLE HYDRAULIC CYLINDERS,” filed Mar. 8, 2000.
Continuations (1)
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Number |
Date |
Country |
Parent |
09801266 |
Mar 2001 |
US |
Child |
10318247 |
Dec 2002 |
US |