Fluid handling – Line condition change responsive valves – Pilot or servo controlled
Patent
1998-11-24
2000-10-24
Michalsky, Gerald A.
Fluid handling
Line condition change responsive valves
Pilot or servo controlled
137492, G05D 700
Patent
active
061351423
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an automatic-control valve device with an automatic restriction control passage to be installed in a fluid conducting pipeline. More specifically, the present invention relates to improvements in an automatic-control lift valve disclosed in JP-B-8-6837 (hereinafter referred to as "original invention"). The present invention intends to provide a novel valve to be used as a pressure control valve convenient for conveying and distributing water, capable of saving maintenance work and of being formed without difficulty in securing a watertight joint in a closed state even in a large size or high-pressure passage, provided with a pilot valve unit omitting all elements for a fixed restriction control passage, such as needle valves and cocks, having valves capable of automatically opening for self-cleaning operation when clogged, and having functions to limit the flow of a fluid automatically so that the excessive fluid may not be supplied to downstream components as well as functions of a pressure control valve. The present invention also intends to provide a convenient automatic-control valve device capable of easily incorporating therein a liquid level control functions and emergency shutoff functions.
In this description, the term "water" is used as a general designation of fluids.
BACKGROUND ART
Generally known automatic-control valve devices prevalently used for controlling pressure or flow rate sense the pressure of a fluid flowing in the associated pipeline, and operate a main valve driving piston by a pilot valve operated by controlling the flow rate of the fluid by a fixed restriction control device, such as a needle valve. Those generally known automatic-control valve devices, however, have problems in the durability of a sealing mechanism for sealing the main valve driving piston and in the machining accuracy of the component parts of the sealing mechanism. Those generally known automatic-control valve devices need a fixed restricting device, such as a needle valve, in a passage for supplying a fluid to apply a pressure at a position on the upstream side of the main valve to the main valve driving piston to drive the main valve gradually in order that pressure pulsation due to the sudden change of the flow of the fluid can be avoided. The fixed restricting device, which has a minute, precision construction, is liable to be clogged with sand or dust.
The automatic-control lift valve of the original invention disclosed in JP-B-8-6837 solves those problems, is provided with a pilot valve unit not provided with any fixed restricting device, such as a needle valve, and free from clogging, and a main valve unit capable of being easily and simply sealed, capable of holding pressure or flow rate in a passage on the downstream side of the main valve unit at a predetermined value, and having a simple construction.
The gist of the construction of this prior art automatic-control lift valve device mentioned in the specification are itemized as follows.
(1) In the automatic-control lift valve device as an automatic constant-pressure valve as shown in FIG. 9, a main valve unit having a main valve casing 1 has a main valve element 5 and a main valve driving member 6 formed integrally with the main valve element 5, the main valve driving member 6 is fitted for sliding movement in a chamber c defined by a cylindrical wall 8 in the main valve casing 1, the main valve element 5 is disposed on the upstream side of a main valve opening b, a pilot valve A which closes to close the main valve unit when the pressure of a fluid in a downstream passage of the main valve unit rises beyond a predetermined level and a pilot valve B which closes to open the main valve unit when the pressure of the fluid in the downstream passage of the main valve unit drops below a predetermined level are connected by a passage m connected to a main valve driving pressure chamber e formed between the main valve driving member 6 and a main valve top 2, and the pilot valve A and the pilot valve B
REFERENCES:
patent: 5735308 (1998-04-01), Yokota et al.
Yokota Hiroshi
Yokota Shingo
Kabushiki Kaisha Yokota Seisakusho
Michalsky Gerald A.
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