Valves and valve actuation – Fluid actuated or retarded – Pilot or servo type motor
Reexamination Certificate
2000-07-07
2001-11-13
Fox, John (Department: 3753)
Valves and valve actuation
Fluid actuated or retarded
Pilot or servo type motor
C251S033000
Reexamination Certificate
active
06315266
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a pilot-operated flow regulating valve including a main valve element arranged in a flow passage to which high-pressure fluid is supplied, a circular valve seat formed in said flow passage, said main valve element facing said valve seat, a pressure receiving member arranged with its front surface exposed to the fluid in said flow passage, said pressure receiving member being moveable in accordance with a differential pressure between a fluid pressure applied to said front surface in a first portion of said flow passage and a pressure in a pressure control chamber bounded by a rear surface of said pressure receiving member, a driving force transmitting member interposed between said pressure receiving member and said main valve element so as to move said pressure receiving member and said main valve element in directions such that said main valve element moves towards said valve seat into a first, completely seated position and away from said valve seat into other positions allowing a fluid flow through said valve seat, a pilot passage connecting said pressure control chamber with said second portion of said flow passage located at a side of said valve seat opposite to said pressure receiving member, a leak passage of small cross-sectional area permitting leak of fluid between said pressure control chamber and said first portion of said flow passage, urging means for urging said main valve element in a direction opposite to a driving direction of said pressure receiving member, and a pilot passage constant differential-pressure regulating valve which opens when a differential pressure between an inlet and an outlet of said pilot passage becomes higher than a given pressure in order to keep said differential pressure essentially constant In operation of said pilot-operated flow regulating valve the differential pressure between the inlet and the outlet sides of the valve is kept constant to thereby regulate the flow rate of fluid through said valve seat.
2. Discussion of the Related Art
In flow regulating valves in general the differential pressure between the inlet and outlet sides of the valve is regulated by a solenoid such that the flow rate is controlled in accordance with the set differential pressure. For extremely high fluid pressures, however, the solenoid needs to be strong and has to have a huge size when directly actuating the main valve element, compared with the cross-sectional area of the flow passage for the fluid. Strong solenoids are expensive. Said combination lacks practicability.
To avoid said drawback it is known in practice to use pilot-operated types of flow regulating valves for a high pressure applications. Unlike a simple pilot-operated on/off valve, pilot-operated flow regulating flow valves need a constant differential-pressure regulating pilot valve for opening and closing a pilot passage. The solenoid then only needs to be strong enough to actuate the pilot valve which is actuatable by much less force than the main valve element. As a result, a small sized, cheap solenoid, preferably a proportional solenoid, can be used, the actuating force of which is proportional to the value of the current supplied to its coil.
In a conventional pilot operated flow regulating valve the main valve element is arranged in a flow passage for high-pressure fluid and faces the valve seat formed in the flow passage. At the rear side of a pressure receiving member a pressure control chamber is defined. The front surface of the pressure receiving member is exposed to the fluid in the first portion of said flow passage so that the pressure receiving member moves in response to different pressures applied to its front and rear surfaces. A driving force transmitting member is interposed between said pressure receiving member and the main valve element. Also, a pilot passage connects said pressure control chamber with a second portion of the flow passage located below said valve seat opposite the pressure receiving member front surface. A leak passage of small cross-sectional area permits leak of fluid between the pressure control chamber and said first portion of the flow passage. Urging means urge the main valve element in a direction opposite to the driving direction of said pressure receiving member. Said design of a pilot operated flow regulating valve is known from practice. In said conventional pilot-operated flow regulating valve said main valve element when lifted from its valve seat is in a state that it can freely vibrate, e.g. in lateral direction. If said main valve element occasionally vibrates because of the fluid flow and repeatedly collides with its surrounding, e.g. the valve seat, disturbing noise is produced. Said phenomenon is known as “valve rattling”. Furthermore, excessive wear may develop at the main valve element and/or at the valve seat.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the invention to provide a silent pilot-operated flow regulating valve wherein the main valve element does not vibrate freely, e.g. in lateral direction, when said main valve element opens the flow passage. Said main valve element should not constitute a noise source.
According to a first aspect of the invention in said other positions of said main valve element at least one of said urging means and said driving force transmitting member forces said main valve element into a vibration suppressing contact with only a portion of said circular valve seat.
According to a further aspect of the invention while said main valve element is opened or brought into one of said other positions an urging force of said urging means acts upon said main valve element so as to tilt the same and to thereby restrict vibration of said main valve element.
Whenever the main valve element clears the flow passage for fluid through the valve seat the urging force of the urging means acts upon the main valve element so as to tilt it and to thereby restrict vibration of the main valve element. Consequently, the main valve element is prevented from vibrating freely while opened so that the pilot-operated flow regulating valve never constitutes a noise source. In particular the urging force is tilting the main valve element laterally and into a vibration suppressing contact with only a part of the circular valve seat. In a structurally simple way said tilting effect is produced at the main valve element either by the urging means or the force transmitting member or by the mechanical co-action of both. This intentional contact is maintained by said urging force in said other positions of said main valve element, i.e. as long as said main valve element is not completely seated on said circular valve seat. Since the main valve element is tilted laterally into the vibration suppressing contact with only a part of the circular valve seat, an opening remains between the main valve element and the valve seat allowing the fluid flow. The intentionally created vibration suppressing contact hinders the valve element from vibrating, mainly in lateral direction, and thus avoids the generation of disturbing noise. Furthermore, since the main valve element is hindered to vibrate freely dangerous and sudden collisions between the main valve element and the valve seat are avoided. The life duration of the valve is increased.
REFERENCES:
patent: 4596271 (1986-06-01), Brundage
patent: 5979862 (1999-11-01), Wolfges
Hirota Hisatoshi
Inoue Yusuke
Tsugawa Tokumi
Fox John
Nilles & Nilles S.C.
TGK Co. Ltd.
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