Patent ID: 6390441
Filing Date: 2002-05-21
Classification: F16K

Abstract:
A solenoid pilot operated valve, comprising a housing in which a valve seat is formed in a cylindrical housing bore, said valve seat defining a communication passage between a high-pressure side fluid passage and a low-pressure side fluid passage, a main valve member movably arranged in said cylindrical bore facing said valve seat from the side of said high-pressure side fluid passage, said high-pressure side fluid passage communicating with said low-pressure side fluid passage via a pressure control chamber provided at the rear side of said main valve member opposite to said valve seat, and a pilot hole formed in said main valve member, said pilot hole terminating at the side of said pressure control chamber at a pilot valve seat, and a pilot valve element at the side of said pressure control chamber operated by magnetic force produced by a coil to control pilot operation open and closed states of said main valve member,wherein a sleeve is arranged coaxially with said main valve member and extends from said pressure control chamber through said coil, said sleeve receives an axially moveable core, a plunger is arranged between said core and said main valve member, an axial part of which is axially movably received in said sleeve, a portion of said plunger at the side of said main valve member defines a cavity receiving said pilot valve element and communicating with said pressure control chamber through at least one communication hole, said cavity being open towards said pilot valve seat and said pilot hole formed in said main valve member, said plunger is separated from said main valve member such that it is apt to move towards said core by attraction when said coil is energised, a longitudinal shaft is moveably received in said plunger and extends through said plunger along its axis, a portion of said shaft facing towards said main valve member and having said pilot valve element is arranged so as to face said pilot valve seat attached to said main valve member, and a spring is arranged in said cavity of said plunger axially urging said shaft such that in a de-energised condition of said coil said pilot valve element is separated from said pilot valve seat and an end face of said shaft at the side of said core projects by a predetermined length beyond the adjacent end face of said plunger.