Patent ID: 6263905
Filing Date: 2001-07-24
Classification: F16K,G05D,Y10T

Abstract:
An automatic regulating valve apparatus comprising: a main valve unit and a pilot valve unit operatively connected to the main valve unit to control the main valve unit,wherein the main valve unit comprises a main valve casing, a main valve element disposed in the main valve casing, and a main valve driving member disposed in the main valve casing together with the main valve element and having a pressure receiving area greater than that of the main valve element, the main valve element is disposed on an upstream side of a valve seat so as to form a restricting passage between the main valve element and the main valve seat, the main valve driving member is disposed for sliding movement in a space defined by a cylindrical wall formed in the main valve casing so as to define a main valve driving pressure chamber together with the cylindrical wall, a restrictor is disposed in a passage extending through the main valve unit;the pilot valve unit comprises a pilot valve A and a pilot valve B which are operated by a balance of counteracting forces respectively produced by a pressure difference across the restrictor and a fixed-pressure applying member, the pilot valve A opens when the pressure difference across the restrictor rises above a predetermined level and closes when the same drops below the predetermined level, the pilot valve B closes when the pressure difference across the restrictor rises above the predetermined level and opens when the same drops below the predetermined level; andthe pilot valve A and the pilot valve B are arranged in series and connected between the upstream and the downstream side of the main valve unit by connecting passages with a chamber between the pilot valves A and B connected to the main valve driving pressure chamber; andwherein a valve element is further provided, said valve element being capable of closing when liquid level on the downstream side of the main valve unit rises above a predetermined level and of opening when the same falls below the predetermined level, and placed in series in a connecting passage connected to the pilot valve B.