Electro-hydraulic valve control system and method

A method of controlling an electro-hydraulic valve arrangement disposed in fluid connection between a source of pressurized fluid and an actuator, comprising:

• receiving a signal to open the electro-hydraulic valve arrangement to provide a flow of fluid from the source of pressurized fluid to the actuator;
• determining a source pressure representative of the pressure of fluid between the source of pressurized fluid and the electro-hydraulic valve arrangement;
• determining an actuator pressure representative of the pressure of the fluid between the electro-hydraulic valve arrangement and the actuator;
• modifying the received signal to prevent the electro-hydraulic valve arrangement from opening when the source pressure is less than the sum of the actuator pressure and a safety margin to prevent a reverse flow of fluid from the actuator to the source of pressurized fluid.

A method of controlling an electro-hydraulic valve arrangement disposed in fluid connection between a source of pressurized fluid and an actuator, comprising the steps of:

• determining a requested flow rate of fluid to be provided to the actuator based on load conditions;
• determining a source pressure representative of the pressure of fluid between the source of pressurized fluid and the electro-hydraulic valve arrangement;
• determining an actuator pressure representative of the pressure of the fluid between the electro-hydraulic valve arrangement and the actuator;
• computing a scaling factor based on the difference between the source pressure and the actuator pressure;
• applying the scaling factor to the requested flow rate to determine an actual flow rate of fluid to provide to the actuator;
• and
• adjusting the electro-hydraulic valve arrangement to a position where the actual flow rate of fluid is provided to the actuator.

A system for controlling a hydraulic actuator, comprising:

• a hydraulic actuator;
• a source of pressurized fluid;
• an electro-hydraulic valve arrangement in fluid connection with the source of pressurized fluid and the hydraulic actuator and operable to control a flow rate of fluid from the source of pressurized fluid to the hydraulic actuator;
• a first pressure sensor operable to sense a source pressure representative of the pressure of the fluid between the source of pressurized fluid and the electro-hydraulic valve arrangement;
• a second pressure sensor operable to sense an actuator pressure representative of the pressure of the fluid between the electro-hydraulic valve arrangement and the hydraulic actuator;
• and
• a control device for controlling the electro-hydraulic valve arrangement, the control device operable to receive a signal to open the electro-hydraulic valve arrangement and prevent the electro-hydraulic valve arrangement from opening when the source pressure is less than the actuator pressure, wherein the control device is further operable to close the electro-hydraulic valve arrangement when the source pressure drops below the actuator pressure.

A system for controlling a hydraulic actuator, comprising:

• a hydraulic actuator including a first chamber and a second chamber;
• a source of pressurized fluid;
• an electro-hydraulic valve arrangement in fluid connection with the source of pressurized fluid and the hydraulic actuator and including a series of independent metering valves adapted to control a flow of fluid into and out of the first and second chambers of the hydraulic actuator;
• a first pressure sensor operable to sense a source pressure representative of the pressure of the fluid between the source of pressurized fluid and the electro-hydraulic valve arrangement;
• a second pressure sensor operable to sense an actuator pressure representative of the pressure of the fluid between the electro-hydraulic valve arrangement and the hydraulic actuator;
• and
• a control device for controlling the electro-hydraulic valve arrangement, the control device operable to receive a signal to open the electro-hydraulic valve arrangement and prevent the electro-hydraulic valve arrangement from opening when the source pressure is less than the actuator pressure.

A system for controlling a hydraulic actuator, comprising:

• a hydraulic actuator;
• a source of pressurized fluid;
• an electro-hydraulic valve arrangement in fluid connection with the source of pressurized fluid and the hydraulic actuator and operable to control a flow rate of fluid from the source of pressurized fluid to the hydraulic actuator;
• a first pressure sensor operable to sense a source pressure representative of the pressure of the fluid between the source of pressurized fluid and the electro-hydraulic valve arrangement;
• a second pressure sensor operable to sense an actuator pressure representative of the pressure of the fluid between the electro-hydraulic valve arrangement and the hydraulic actuator;
• a control device for controlling the electro-hydraulic valve arrangement, the control device operable to receive a signal to open the electro-hydraulic valve arrangement and prevent the electro-hydraulic valve arrangement from opening when the source pressure is less than the actuator pressure;
• and
• a remote control operable to generate the signal to open the electro-hydraulic valve arrangement.

A system for controlling a hydraulic actuator, comprising:

• a hydraulic actuator;
• a source of pressurized fluid;
• an electro-hydraulic valve arrangement in fluid connection with the source of pressurized fluid and the hydraulic actuator and operable to control a flow rate of fluid from the source of pressurized fluid to the hydraulic actuator;
• a first pressure sensor operable to sense a source pressure representative of the pressure of the fluid between the source of pressurized fluid and the electro-hydraulic valve arrangement;
• a second pressure sensor operable to sense an actuator pressure representative of the pressure of the fluid between the electro-hydraulic valve arrangement and the hydraulic actuator;
• and
• a control device for controlling the electro-hydraulic valve arrangement, the control device operable to receive a signal to open the electro-hydraulic valve arrangement to provide a requested fluid flow, the control device further operable to compute a scaling factor based on the difference between the source pressure and the actuator pressure and to open the electro-hydraulic valve arrangement to provide an actual fluid flow based on the application of the scaling factor to the requested fluid flow.