Method and system for electrohydraulic valve control

A control system for an electrohydraulic valve used to control the operation of a work element through the use of operator input control mechanisms generating operator input signals upon the application thereof, the valve being connected to the work element via a hydraulic circuit which includes actuator means coupled to the work element for controlling the operation thereof, the control system comprising:

• a flow sensor positioned in communication with the valve and adapted to determine an actual valve output flow rate of a hydraulic fluid flowing therethrough, the flow sensor outputting a signal indicative of the actual valve output flow rate;
• a pressure sensor positioned in communication with the actuator means and adapted to sense a load pressure being applied to the actuator means, the pressure sensor outputting a signal indicative of the load pressure;
• desired valve output flow rate determinator means in communication with the pressure sensor and the operator input control mechanisms for receiving the load pressure signal and the operator input signal and determining a desired valve output flow rate for the valve based thereon, the determinator means outputting a signal indicative of the desired valve output flow rate;
• a comparator in communication with the flow sensor and the desired valve output flow rate determinator means and adapted to receive signals therefrom, said comparator being operable to compare the actual valve output flow rate with the desired valve output flow rate and produce a comparator output signal representing a difference therebetween;
• and
• a controller in communication with the comparator and the valve and adapted to receive the comparator output signal and modify an input flow rate signal to the valve based upon the comparator output signal such that the desired valve output flow rate from the valve is achieved.

A control system for an electrohydraulic valve used to control the operation of a work element through the use of operator input control mechanisms generating operator input signals upon the application thereof, the valve having a spool for controlling fluid flow therethrough, the valve further being connected to the work element via a hydraulic circuit which includes a hydraulic pump for providing fluid flow to the work element and actuator means coupled to the work element for controlling the operation thereof, the control system comprising:

• a pressure sensor positioned in communication with the actuator means and adapted to sense a load pressure being applied to the actuator means, the pressure sensor outputting a signal indicative of the load pressure;
• pressure drop determinator means for determining a pressure drop across the valve, the pressure drop determinator means outputting a signal indicative of the pressure drop;
• a spool displacement sensor positioned in communication with the spool and adapted to determine a displacement of the spool relative to a predetermined position, the spool displacement sensor outputting a signal indicative of the spool displacement;
• an actual valve output flow rate calculator adapted to receive the spool displacement signal and the pressure drop signal and calculate an actual valve output flow rate of the hydraulic fluid flowing from the valve, the calculator outputting a signal indicative of the actual valve output flow rate;
• desired valve output flow rate determinator means in communication with the pressure sensor and the operator input control mechanisms for receiving the load pressure signal and the operator input signal and determining a desired valve output flow rate for the valve based thereon, the output flow rate determinator means outputting a signal indicative of a desired valve output flow rate;
• a comparator in communication with the actual valve output flow rate calculator and the desired flow rate determinator means and adapted to receive signals therefrom, said comparator being operable to compare the actual valve output flow rate with the desired valve output flow rate and produce a comparator output signal representing a difference therebetween;
• and
• a controller in communication with the comparator and the valve and adapted to receive the comparator output signal and modify an input flow rate signal to the valve based upon the comparator output signal such that the desired valve output flow rate from the valve is achieved.

A method for controlling an electrohydraulic valve used to control the operation of a work element connected to a work machine through the use of operator input control mechanisms generating operator input signals upon the application thereof, the valve being connected to the work element via a hydraulic circuit which includes actuator means coupled to the work element for controlling the operation thereof and a hydraulic pump for providing fluid flow to the actuating means, the control system comprising:

• determining an actual valve output flow rate of the hydraulic fluid flowing from the valve;
• sensing a load pressure being applied to the work element;
• determining a desired valve output flow rate for the valve based upon the load pressure and the operator input signal;
• comparing the actual valve output flow rate to the desired valve output flow rate;
• and
• modifying an input flow rate signal to the valve based upon the difference between the actual valve output flow rate and the desired valve output flow rate to achieve the desired valve output flow rate.