Seismic Vibrator Servo Valve with Proportional Linear Pressure Feedback

A method of manufacture of an improved apparatus for pressure control of a seismic vibrator or vibration machine having a sliding circular valve spool with a left piston, a center piston, a right piston, a left rod disposed between the left piston and the center piston, a right rod disposed between the center piston and the right piston, a left cylinder pressure chamber formed around the left rod for receiving pressurized fluid, a right cylinder pressure chamber formed around the right chamber for receiving pressurized fluid, a left feedback passageway sampling pressure from the left cylinder pressure chamber and directing force to a right end drive surface of the spool, and a right feedback passageway sampling pressure from the right cylinder pressure chamber and directing force to a left end drive surface of the spool, the method comprising:

• providing, to a servo valve or vibration machine, a left additional passageway conducting a portion of sampled pressure from the left cylinder pressure chamber to only a portion of the right end drive surface of the spool, wherein the portion of the right end drive surface is less that of the entirety of the right end drive surface;
• and
• providing, to a servo valve or vibration machine, a right additional passageway conducting a portion of sampled pressure from the right cylinder pressure chamber to only a portion of the left end drive surface of the spool, wherein the portion of the left end drive surface is less that the entirety of the left end drive surface;
• thereby providing at least two additional passageways configured to provide linear proportional pressure feedback in spool movement control.

An improved pressure control method for a seismic vibrator or vibration machine having a sliding circular valve spool with a left piston, a center piston, a right piston, a left rod disposed between the left piston and the center piston, a right rod disposed between the center piston and the right piston, a left cylinder pressure chamber formed around the left rod for receiving pressurized fluid, a right cylinder pressure chamber formed around the right chamber for receiving pressurized fluid, a left feedback passageway sampling pressure from the left cylinder pressure chamber and directing force to a right end drive surface of the spool, and a right feedback passageway sampling pressure from the right cylinder pressure chamber and directing force to a left end drive surface of the spool, the method improvement comprising:

• conducting, a left additional passageway, a portion of sampled pressure from the left cylinder pressure chamber to only a portion of the right end drive surface of the spool, wherein the portion of the right end drive surface is less that of the entirety of the right end drive surface;
• and
• conducting, via a right additional passageway, a portion of sampled pressure from the right cylinder pressure chamber to only a portion of the left end drive surface of the spool, wherein the portion of the left end drive surface is less that the entirety of the left end drive surface;
• thereby providing at least two additional passageways configured to provide linear proportional pressure feedback in spool movement control.