| 摘要 |
<p>THREE-WAY NORMALLY CLOSED PILOT VALVE A three-way normally closed only, pilot valve for supplying pressurized pilot air to a fluid flow control valve, such as a four-way valve, a three-way valve, a two-way valve, or the like, for shifting the main spool valve of such valves. The pilot valve includes a valve body with a pressurized pilot air inlet port, a cylinder port, and an exhaust port. The inlet port is connected by a first passageway to the cylinder port. The cylinder port is connected by a second passageway to the exhaust port. A poppet spool valve is movably mounted in the valve body between an inoperative position for blocking the first passageway means, and an operative position for opening the first passageway means and blocking the second passageway means. A spring and air assist return means moves the poppet spool valve to the inoperative position. A solenoid moves the poppet spool valve to the operative position. The poppet spool valve has only one dynamic seal. The pilot valve includes a pair of longitudinally spaced apart, sharp edged valve seats which are alternately engaged, by a pair of longitudinally spaced annular valve members on the poppet spool valve, when the poppet spool valve is moved between the operative and inoperative positions.</p> |
