| 摘要 |
948,425. Valves. ROSS OPERATING VALVE CO. Oct. 5, 1962 [Nov. 27, 1961], No. 37841/62. Heading F2V. A valve 37 comprises a spool slidably mounted in a body 35, an inlet chamber 41 connectible to a source of constant pressure, such as the inlet 15 of a main valve 22, a signal chamber 54 alternately connectible by a valve 32 to pressure and exhaust, axially spaced inlet and exhaust valves 46, 48 carried by the spool, a working port 59 between the inlet and exhaust valves, an exhaust port 55 between the exhaust valve 48 and the signal chamber, and a seal 44 separating the exhaust port and the signal chamber, the relative areas of the valves and seal being such that part opening of the inlet valve 46 causes the spool to shift rapidly fully to open the inlet valve 46 and part opening of the exhaust valve causes the spool to shift rapidly fully to open the exhaust valve 48. When the valve 32 is connected to pressure a restriction 29 permits a gradual pressure increase in the chamber 54 moving the spool to the right against the resistance of inlet pressure in the chamber 41 until the exhaust valve 48 closes by entering a bore 43, and subsequently, the inlet valve 46 opens by leaving a bore 42. Inlet pressure is now able to act on both sides of the seal 46 and the spool is moved rapidly to the right to open the port 59 fully and allow the main valve 22 to connect a working port 17 to exhaust 16 instead of the inlet 15. Connection of the chamber 54 by the valve 32 to exhaust permits a rapid fall of pressure through a check valve 28 so that the spool is returned to its original position by the inlet pressure in chamber 41. The check valve may be reversed. In a modified arrangement, both supply and exhaust flows to the chamber 54 are restricted and an additional fluid-actuated valve is provided between the chamber 54 and the bore 42 so that the chamber 54 is connected with the inlet chamber 41 and with the exhaust port 55 as soon as the inlet and exhaust valves 46, 48 are opened. |
