Method of measuring operation characteristic of proportional electromagnetic control valve, method of controlling operation of hydraulic cylinder, and method of modifying operation characteristic of proportional electromagnetic control valve

A method of measuring an operation characteristic of a proportional electromagnetic control valve, in a hydraulic circuit which actuates a hydraulic cylinder, the control valve being, operable to control a hydraulic pressure and a flow rate based on a load of electrical current for the control valve, said method comprising the steps of:

• if the proportional electromagcnetic control valve is a proportional electromagnetic pressure control valve for controlling a pressure of the hydraulic cylinder
• (a) cutting off a flow of the hydraulic circuit into the cylinder;
• (b) successively loading a predetermined series of electrical currents for the proportional electromagnetic pressure control valve;
• for each of said loaded electrical currents,
• (c) measuring a pressure of the hydraulic circuit at regular time intervals;
• (d) calculating a difference in pressure between a then-current measured pressure and a preceding measured pressure;
• (e) repeating said steps (c) and (d) until such pressure difference becomes smaller than a predetermined reference value;
• and
• when said pressure difference becomes smaller than a predetermined reference value,
• (f) defining said measured hydraulic pressure corresponding to said loaded electrical current as the operation characteristic of said proportional electromagnetic pressure control valve with respect to pressure-electric current.

A method of measuring an operation characteristic of a proportional electromagnetic control valve, in a hydraulic circuit which actuates a hydraulic cylinder, the control valve being operable to control a hydraulic pressure and a flow rate based on a load of electrical current for the control valve, said method comprising the steps of

• if the proportional electromagnetic control valve is a proportional electromagnetic flow control valve for controlling a flow rate of the hydraulic cylinder,
• (a) successively loading different magnitudes of electrical current for the proportional electromagnetic flow control valve;
• for each of said different magnitudes of electrical currents,
• (b) actuating the hydraulic cylinder by the flow control valve in accordance with said loaded electrical current;
• (c) measuring a distance by which a hydraulic ram of the hydraulic cylinder has been moved in a predetermined time as the result of said actuating in step (b);
• (d) calculating a velocity of the hydraulic ram of the cylinder using said measured distance;
• and
• (e) obtaining a velocity-electric current characteristic of said proportional electromagnetic flow control valve based on said loaded magnitude of electrical current and the calculated velocity of the ram.

A method for controlling a hydraulic cylinder which is actuated by a hydraulic circuit, a proportional electromagnetic control valve in the hydraulic circuit being operable to control a hydraulic pressure and a flow rate based on a load of electrical current for the control valve, said method comprising the steps of:

• if the proportional electromagnetic control valve is a proportional electromagnetic pressure control valve for controlling a pressure of the hydraulic cylinder,
• (a) cutting off a flow of the hydraulic circuit into the cylinder,
• (b) successively loading a predetermined series of electrical currents for the proportional electromagnetic pressure control valve;
• for each of said loaded electrical currents.
• (c) measuring a pressure of the hydraulic circuit at regular time intervals;
• (d) calculating a difference in pressure between the then-current measured pressure and a preceding measured pressure;
• (e) repeating said steps (c) and (d) until such pressure difference becomes smaller than a predetermined reference value;
• when said pressure difference becomes smaller than a predetermined reference value,
• (f) defining said measured hydraulic pressure, corresponding to said loaded electrical current, as the operation characteristic of said proportional electromagnetic pressure control valve with respect to pressure-electric current;
• (g) storing in a memory said defined pressure-electric current characteristic of said proportional electromagnetic pressure control valve;
• in an actual operation of the hydraulic cylinder,
• (h) designating a target pressure of the hydraulic cylinder,
• (i) selecting, from said pressure-electric current characteristic stored in the memory, an electric load current corresponding to the target pressure;
• and
• (j) loading said selected electric load current to said proportional electromagnetic pressure control valve so as to control said hydraulic cylinder.

A method for controlling a hydraulic cylinder which is actuated by a hydraulic circuit, a proportional electromagnetic control valve in the hydraulic circuit being operable to control a hydraulic pressure and a flow rate based on a load of electrical current for the control valve, said method comprising the steps of:

• if the proportional electromagnetic control valve is a proportional electromagnetic flow control valve for controlling a flow rate of the hydraulic cylinder,
• (a) successively loading different magnitudes of electrical current for the proportional electromagnetic flow control valve;
• for each of said different magnitudes of electrical currents,
• (b) actuating the hydraulic cylinder by the flow control valve in accordance with said loaded electrical current;
• (c) measuring a distance by which a hydraulic ram of the hydraulic cylinder has been moved in a predetermined time as the result of said actuating time in step (b);
• (d) calculating a velocity of the hydraulic ram of the cylinder based on said measured distance;
• (e) obtaining a velocity-electric current characteristic of said proportional electromagnetic flow control valve based on said magnitude of electrical current and the calculated velocity of the ram;
• (f) storing in a memory said obtained velocity-electric current characteristic of said proportional electromagnetic flow control valve;
• in an actual operation of the hydraulic cylinder,
• (g) designating a target velocity of the hydraulic ram;
• (h) selecting, from said velocity-electric current characteristic stored in the memory, an electric load current corresponding to the desired velocity;
• and
• (i) loading said selected electric load current to said proportional electromagnetic flow control valve so as to control said hydraulic cylinder.

A method for controlling a hydraulic cylinder which is actuated by a hydraulic circuit, a proportional electric control valve in the hydraulic circuit being operable to control a hydraulic pressure and a flow rate based on a load of electrical current for the control valve, said method comprising the steps of:

• if the proportional electromagnetic control valve is a proportional electuomagnietic pressure control valve for controlling a pressure of the hydraulic cylinder,
• (a) cutting off a flow of the hydraulic circuit into the cylinder,
• (b) successively loading a predetermined series of electrical currents lor the proportional electromagnetic pressure control valve;
• for each of said loaded electrical currents,
• (c) measuring a pressure of the hydraulic circuit at regular time intervals;
• (d) calculating a difference in pressure between the then-current measured pressure and a preceding measured pressure;
• (e) repeating said steps (c) and (d) until such pressure difference becomes smaller than a predetermined reference value;
• when said pressure difference becomes smaller than a predetermined reference value;
• (f) defining said measured hydraulic pressure, corresponding to said loaded electrical current, as the operation characteristic of said proportional electromagnetic pressure control valve with respect to pressure-electric current;
• (g) creating a table of said defined operation characteristic of pressure-electric current;
• (h) calculating a function based on said created table;
• (i) storing in a memory said function calculated in said step (g);
• in an actual operation of the hydraulic cylinder,
• (j) reading said stored function;
• (k) calculating, based on said read function, an electric current corresponding to a given target pressure value;
• and
• (l) loading said electric current, which is calculated in said step (j), to said proportional electromagnetic pressure control valve so as to control said hydraulic cylinder.

A method for controlling a hydraulic cylinder which is actuated by a hydraulic circuit, a proportional electromagnetic control valve in the hydraulic circuit being operable to control a hydraulic pressure and a flow rate based on a load of electrical current for the control valve, said method comprising the steps of:

• if the proportional electromagnetic control valve is a proportional electromagnetic flow control valve for controlling a flow rate of the hydraulic cylinder,
• (a) successively loading different magnitudes of electrical current for the proportional electromagnetic flow control valve;
• for each of said different magnitudes of electrical current,
• (b) actuating the hydraulic cylinder by the flow control valve in accordance with said loaded electrical current;
• (c) measuring a distance by which a hydraulic ram of the hydraulic cylinder has been moved in a predetermined time as the result of said actuating in step (b);
• (d) calculating a velocity of the hydraulic ram of the cylinder based on said measured distance;
• and
• (e) obtaining a velocity-electric characteristic of said proportional electromagnetic flow control valve based on said loaded magnitude of electrical current and the calculated velocity of the ram;
• (f) creating a table of said obtained velocity-electric current characteristic;
• (g) calculating a function based on the table created in step (f);
• (h) storing in a memory said function calculated in step (g);
• in an actual operation of the hydraulic cylinder,
• (i) reading said stored function;
• (j) calculating, based on said read function, an electric current corresponding to a given target velocity value of the hydraulic ram;
• and
• (k) loading said electric current, which is calculated in said step (j), to said proportional electromagnetic flow control valve so as to control said hydraulic cylinder.