Pneumatic pilot-operated control valve assembly

摘要

A pilot operated and pneumatically driven control valve assembly has a pair of pilot operated and pneumatically driven regulators to control the pressurization and venting of a pneumatic cylinder. The pilots of each regulator are alternately driven by a pair of normally open pilot operated valves each of which is in communication with a separate regulator to control the pressurization of that regulator. The pressure acting on the pilot of each regulator controls the flow of air through the regulator and the subsequent magnitude of the pressure within the pneumatic cylinder. Thus, varying the pressure in the pilot of the regulator varies the resulting pressure in the pneumatic cylinder in proportion to the pilot pressure. The pilot operated valves are alternately driven between open and closed positions to alternately drive the pilots of the regulators. The regulators communicate with opposed sides of a piston of a pneumatic cylinder to control the pressurization of the cylinder adjacent each side of the piston. The pneumatic cylinder may be of any type with one current application used to drive the clamp of a welding gun of an electrical resistance welder such as that used in an automotive assembly line.