MXPA06008260A - Pressure loaded pilot valve system and method for a regulator without atmospheric bleed - Google Patents

Abstract

A pressure loaded pilot valve system and method for a regulator valve is provided. The system includes a regulator valve connecting an inlet line to an outlet line, a servo control valve assembly, and a pilot valve assembly. A supply line is connected to the servo control valve, and a pilot loading pressure line connects the servo control valve to the pilot valve assembly. An exhaust line connects the servo control valve to the outlet line, thereby avoiding waste, pollution, etc. associated with bleeding excess pilot pressure to the atmosphere.

Description

For two-letler codes and other abbrevialions. Refer to the "Guidance Notes on Codes and Abbreviations" appearing to the beginning of the regular issue of the PCT Gazette.

PILOT SYSTEM AND METHOD OF PRESSURE CHARGED VALVE. FOR A REGULATOR. NO ATMOSPHERIC PURGE FIELD OF DESCRIPTION This description relates in general to methods and apparatus for controlling regulators and, more particularly, to improvements in systems and methods for operating pilot valves for regulators, charged under pressure.

BACKGROUND OF THE INVENTION Fluid handling systems, which include regulators, often include a pilot valve to facilitate control over the regulator. Often the fluid used in the pilot valve is the same fluid that is being controlled by the regulator. For example, if the fluid that is being handled by the regulator is natural gas, a portion of natural gas can be diverted for use in the pilot valve, in order to control the regulator. Load pressure is used on the pilot valve to adjust the fixed point of the system. Load pressure must be entered when it is necessary to lower the fixed point. Many systems achieve this by mixing excess fluid into the atmosphere. However, it may be undesirable to purge the excess fluid to the atmosphere in some situations, such as when natural gas is used as a charging pressure fluid for the pilot valve, due to possible adverse environmental effects and / or the additional risk of fire, if purge of excess fluid occurs in a confined area.

BRIEF DESCRIPTION OF THE INVENTION A pressure-loaded pilot valve system for a regulating valve includes a regulating valve that connects an inlet line that carries fluid to an inlet pressure, with an outlet line carrying fluid, to an outlet supply pressure. The system additionally includes a servo control valve assembly, a pilot valve assembly, a supply line connected to the servo control valve assembly, which carries fluid to a supply pressure, and a pilot charge pressure line, which carries fluid at a pilot load pressure. An exhaust line connects the servo control valve assembly to the outlet line, which carries fluid to an outlet pressure.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a pilot valve system loaded under pressure, for a regulating valve; and Figure 2 is an enlarged schematic view of a servo control valve assembly, which can be used in the system illustrated in Figure 1.

DETAILED DESCRIPTION Referring initially to Figure 1, a pressure-filled pilot valve system, indicated generally at 10, includes a pilot valve 12, operatively connected to a throttle valve 14 and a servo control valve assembly 16. The servo control valve assembly 16 may include a commercially available servo control valve, such as the servo control valve QB2T, obtainable from Proportion-Air, Inc. A main supply line 18 provides fluid flow at a pressure level of supply to the throttle valve 14, and a main outlet line 20 leads from the throttle valve 14 and carries fluid to an outlet supply pressure. A pilot line 22 connects the main supply line 18 with the servo control valve assembly 16. A filter assembly 24, which may include a water separation capability, may be connected to the supply line 22 and to the valve assembly. of servo control 16 through a servo-feed line. A pilot control line 28 can connect the pilot valve 12 to the main output line, and can also be connected to the servo control valve assembly 16 via a servo line 30. A pilot load pressure line 32 connects the servo control valve assembly 16 with the pilot valve 12, and a main valve load pressure line 34 connects the pilot valve 12 to the regulating valve 14. A fixed restrictor 35 may be provided between the filter assembly 24 and the load pressure line 34 of the main valve. With reference to Figure 2, the servo control valve assembly 16 may include an electronic control unit 36, which may be operatively connected to a supply pressure solenoid valve 38, an outlet pressure solenoid valve 40 and a transducer 42 load pressure. Each of the solenoid valves 38 and 40 can be a normally closed two-way solenoid valve. The load pressure transducer 42 senses the load pressure on the pilot load line 32. The servo control valve assembly 16 can be provided with external control signals through a control cable 44, and power can be provided through a supply cable 46. In operation, the pilot valve system 10 charged under pressure It can operate in the following way. The pilot valve 12, which may be a spring-closed device, is used to operate the throttle valve 14. For example, the throttle valve 14 may include a diaphragm 48 that is operatively connected to a valve plunger 50, and you can use the pilot valve 12 to adjust the fluid pressure in the load pressure line 34 of the main valve. More specifically, the pilot valve 12 may include a pilot valve spring 52 surrounding a pilot valve traction post 54. The pilot valve spring 52 can be adjusted to a desired fixed pulse point. The pilot valve spring 52 may be placed in compression, between a stationary cup-shaped portion 56, of the pilot valve 12, and an adjustable stop nut 58, which may be threadably attached to the pilot valve traction post 54. . The traction post 54 of the pilot valve may be attached to a pilot valve diaphragm 60 and also to a pilot lean cam lever 62. A first leg 64 of the pilot bell cam lever 62 is pivotally fixed to the pilot valve 12, and a second leg 66 of the bell cam lever 62 is pivotally fixed to a rod 68 of the pilot valve, which carries a plunger 70. of pilot valve. With the aforementioned arrangement, the pilot valve spring 52 forcibly carries the pilot valve traction post 54 and the pilot valve diaphragm 60 to the right, in the orientation of figure 1; thus forcibly carrying the plunger 70 of the pilot valve to a closed position, by means of the pilot bell-shaped lever 62 and the pilot valve rod 68. If sufficient fluid pressure is applied through the load-pressure line 32 of pilot, to the pilot valve diaphragm 60, the pilot valve diaphragm 60 forcibly carries the traction post 54 of the pilot valve to the left, in the orientation of Figure 1, thereby forcibly bringing the plunger 70 of the pilot valve to an open position, by means of the pilot levered cam lever 62 and the pilot valve rod 68. The fluid pressure in the pilot load pressure line 32 can be adjusted to a desired fixed point of the pilot-loaded pilot valve system 10. The fluid pressure in the pilot load pressure line 32 can be used to overcome the fixed spring point of the pilot valve 12 and, thus, the fluid pressure in the pilot load pressure line 32 will be greater than the fluid pressure in each of the line 5 of the main outlet 20, the pilot control line 28 and the servo line 30. When it is necessary to lower the fixed point the excess pressure in the pilot load pressure line 32 can be relieved by opening the exhaust pressure solenoid valve 40. Instead of purging this fluid into the atmosphere, which is undesirable due to waste, pollution, etc. , especially when natural gas is used as the working fluid, it can be sent downstream on the main output line 20, by the servo-alveolar line 30. For example, if the fixed pilot point is less than zero (empty), the Pilot load pressure will be superimposed on the force of the spring to control the downstream pressure, at a positive pressure. Specifically, if the fixed point of the spring is 34.47 kPa negative gauge, and the loading pressure is 103.42 kPa gauge, then the control output pressure would be 68.94 kPa gauge. Although the present invention has been described with reference to specific examples, which are intended to be illustrative only, and not to be limiting to the invention, it will be apparent to those of ordinary skill in the art that changes, additions, or omissions can be made therein. the described modalities, without departing from the spirit and scope of the invention. For example, if desired, the servo control valve assembly 16 can be combined with the pilot valve 12, in a complete package.

Claims (10)

1 .- A pilot valve system loaded under pressure for a regulating valve, characterized in that it comprises: a regulating valve that connects a line of intake that carries fluid to an inlet pressure, with an outlet line that carries fluid at a pressure of output supply; a servo control valve assembly; a pilot valve assembly; a supply line connected to the servo control valve assembly, which carries fluid to a supply pressure; a pilot load pressure line, which connects the servo valve assembly with the pilot valve assembly, which carries fluid to a pilot load pressure; and an output line that connects the servo control valve assembly with the output line, which carries fluid to an outlet pressure.

2. The pressure-filled pilot valve system according to claim 1, further characterized in that the pilot valve assembly includes a configuration that is spring-closed.

3. The pressure-loaded pilot valve system according to claim 1, further characterized in that the servo-control valve assembly includes an electronic control unit that is operatively connected to a supply pressure solenoid valve.

4. The pressure-loaded pilot valve system according to claim 3, further characterized in that the electronic control unit is operatively connected to an output pressure solenoid valve.

5. The pressure-loaded pilot valve system according to claim 3, further characterized in that the electronic control unit is operatively connected to a load pressure transducer.

6. The pressure-filled pilot valve system for a regulating valve, characterized in that it comprises: a regulating valve that connects an input line that carries fluid to an inlet pressure, with an outlet line that carries fluid at a pressure of output supply; a servo control valve assembly; a pilot valve assembly including a pilot valve plunger, movable between a closed position and an open position; the diaphragm of the pilot valve being operatively connected to the plunger of the pilot valve, and fixed to a pilot valve pull post; and a pilot valve spring configured to forcibly carry the pilot valve pull post and the pilot valve diaphragm in one direction, in order to forcibly carry the pilot valve plunger to the closed position; a supply line connected to the servo control valve assembly, which carries fluid to a supply pressure; a pilot load pressure line connecting the servo control valve assembly with the pilot valve assembly, which carries fluid to a pilot load pressure; and an output line that connects the servo control valve assembly with the output line, which carries fluid to an outlet pressure.

7. The pressure-loaded pilot valve system according to claim 6, further characterized in that the pilot valve assembly includes a spring-closed configuration.

8. The pressure-loaded pilot valve system according to claim 6, further characterized in that the servo-control valve assembly includes an electronic control unit that is operatively connected to a supply pressure solenoid valve.

9. The pressure-filled pilot valve system according to claim 8, further characterized in that the electronic control unit is operatively connected to an output pressure solenoid valve. The pilot-loaded pilot valve system according to claim 8, further characterized in that the electronic control unit is operatively connected to a load pressure transducer. 1 1 .- A method for operating a pressure-loaded pilot valve system having a regulating valve that connects an input line with an output line, and a pilot valve assembly, characterized in that method comprising: determining a fixed point; adjusts the fluid pressure supplied to the pilot valve assembly, to reach the fixed point; and diverting excessive fluid pressure from the pilot valve assembly to the outlet line, in case the fluid pressure supplied to the pilot valve assembly is adjusted downwardly. 12. The method according to claim 1, further characterized in that the fixed point is determined by obtaining a desired spring force in a pilot valve spring; the desired spring force corresponding to the fixed point. 13. The method according to claim 12, further characterized in that the desired spring force is obtained by adjusting an adjustable stop nut, associated with the pilot valve assembly.