Patent ID: 6240955
Filing Date: 2001-06-05
Classification: F16K,Y10T

Abstract:
A pneumatic pilot assembly, comprising:a pilot body having an upper chamber, a lower chamber and a supply gas inlet to the upper chamber;a vertical passage connecting the upper chamber and the lower chamber, the vertical passage having a ball seat at an upper extent thereof which receives a spring biased ball for opening and closing the vertical passage;a vent passage communicating with the lower chamber;a lateral passage for communicating pilot gas to both the vertical passage and the lower chamber;a pilot stem having an upper extent located within the vertical passage and having a lower extent located within the lower chamber, the upper extent having a tapered mouth opening for contacting and seating with the ball located within the upper chamber, an internal bore, and having an external seating surface below the mouth opening for contacting a seat located at the lower extent of the vertical passage;a pair of vertically spaced diaphragms located within the pilot body for supporting the pilot stem within the pilot body;wherein the vertically spaced diaphragms comprise an upper diaphragm of a first exposed cross sectional area and a lower diaphragm of a second, relatively lesser exposed cross sectional area;wherein unplugging the vent passage activates the upper diaphragm and forms a seat between the pilot mouth opening and the ball; andwherein the act of plugging the vent passage activates the lower diaphragm and disables the upper diaphragm by balancing output gas pressure acting on opposite sides of the upper diaphragm.