Pneumatic control unit for liquid product filling head

Abstract

A pneumatic control head for controlling the supply of a product into a container via a filling head. A manifold has a pilot air duct. A start valve outputs main air to the pilot air duct when actuated by a mechanical switch. A pilot valve activates a cylinder using the main air in response to air pressure in the pilot air duct. A filling head source valve routs either sensing air or blow down air to a filling head output in response to the condition of a blow down valve actuated by a mechanical switch. An overpressure valve exhausts the pilot air duct in response to the sensing air having a pressure higher than normal. The switches each includes a ball bearing captured by a collar. An external cam pushes the ball bearing into the collar, causing the ball bearing to actuate the respective valve. Duct connections to valves are implemented by a single machined plate with a depression that overlaps the duct aperture and valve opening. An o-ring fits into a groove surrounding the depression and valve opening and provides a seal between the plate and the manifold.