Butterfly valve actuator in heating system chimneys - using fuel press. to open valve and return spring to close it

摘要

Actuator comprises a piston (11) in a cylinder (13), with a jointed piston rod (17, 18) connected to a lever arm (19) on the end of the valve spindle (21). The lever arm has an extension (20) beyond the spindle and a second rod (31) pin-jointed to its other end. This rod is held roughly parallel to the cylinder, passing through a hole (34) in a bracket (32) on the cylinder mounting plate (26). A compression spring (29) is held between the bracket and a collar (30) on the rod. When the fuel pump is started, fuel entering the cylinder through a connection (43) in the end remote from the rod pushes the piston to the far end against the return spring, opening the butterfly valve. When the pump stops the return spring action closes the valve again. There is a drain connection (16) from the space behind the piston to the oil return line.