| 摘要 |
<p>1,030,143. Valves. WESTINGHOUSE AIR BRAKE CO. April 7, 1964 [April 17, 1963], No. 14313/64. Heading F2V. A valve comprises a central portion 1, 2 having a double diaphragm piston assembly 5 in which the effective pressure area of the diaphragms 6, 7 can be varied and a first control chamber 14, a cap portion 3 having a second control chamber 12 and a rotatable portion 4 coaxial with and adjacent to the central portion and having a number of passages 34, 35, 36 extending therethrough, each passage, for a specific movement of the rotatable portion, coinciding in turn with a passage 42 to alter the function of the valve. Supply and delivery ports 28, 29 are normally isolated from each other by a spring-loaded valve 25 engaging a seat 27 while the supply pressure acting through aligned passages 34, 42 on the underside of the assembly 5 lifts a valve 17 to connect the delivery port 29 to a vent 23. To close the valve 17 and open the valve 27, pilot pressure is admitted to the chamber 12 through a connection 15. The effective areas of the diaphragms 6, 7 may be altered by replacing the disphragm followers 8, 9 and retainer rings 62 . . . 65. When passage 42 is closed by a blanked recess 51 on the rotatable portion 4 and a valve 57 is unscrewed to open position, the ports 23, 29 and 28 become supply, delivery and exhaust connections, respectively. Supply pressure lifts the valve 17 and flows to the port 29 until pilot pressure in chamber 14 closes valve 17 on to the valve 25 lifting the latter from its seat to place the delivery port 29 in communication with the exhaust port 28. A biasing pressure or vacuum may be admitted to an intermediate control chamber 13 through a port 16. Further rotation of the portion 4 to bring a passage 35 into alignment with the passage 42 causes the valve to close when outlet pressure has risen sufficiently to overcome the pilot pressure. One diaphragm may be omitted and a loading spring provided in the chamber 12 or 13.</p> |
