US3053448A

US3053448A - Fluid flow control system having slow opening positive closing valve

Info

Publication number: US3053448A
Application number: US645366A
Authority: US
Inventors: Werter Jay P Au; Leigh G Tanger
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-03-11
Filing date: 1957-03-11
Publication date: 1962-09-11
Anticipated expiration: 1979-09-11

Description

Sept.vv 11,, 11962: J7. p; u: wER-TERs ET'AL 3,053,448

FLUID: mow CONTRQIL. SYSTEM! HAVING smw OPENING: Po'smmmin (imam-NE: VALVE:

Filed? Mama. II 195% 9a 12; M I23 46 INVENTORSJ Jay P ALZ'WerteF'MJ a; y Leigh 6. Hinge/r United States Patent Oflfice 3,053,448 Patented Sept. 11, 1962 3,053,448 FLUID FLOW CONTROL SYSTEM HAVING SLOW OPENING POSITIVE CLOSING VALVE Jay P. Au Werter, Cleveland, Ohio, and Leigh G. Tanger, Scottsville, N.Y. Filed Mar. 11, 1957, Ser. No. 645,366 8 Claims. (Cl. 236-80) This invention relates to fluid flow control systems and, more particularly, to automatic control of fluid through a pipe line from a source to a use in which a motorized valve governs the fluid flow, the actuation of the motorized valve being regulated to obtain the desired characteristics in the flow.

In the operation of fluid flow control systems fast opening of the main valves is not always desirable and difficuties have been encountered with fast opening motorized valves customarily used in such systems, particularly those systems associated with steam and vapor heating installations. Such valves are characteristically designed to open when a demand for heating steam is felt by the thermostat or other sensing element controlling the system and to close when the demand is satisfied. The rate and extent of opening of the motorized valve are usually directly related to the demand for fluid on the use side of the motorized control valve. That is to say, in a steam heating system for a building a strong demand for fluid or steam, such as occurs when the thermostat is advanced to a higher temperature range after a period of shutdown, produces immediate opening of the valve to its full open position. When the demand for steam or fluid is intermittent and relatively low, as during continuous operation of a building heating installation during mild weather, the motorized valve may be opened to a lesser extent than in the case of the heavy steam demand mentioned. Additionally, the closing of the valve usually takes place gradually depending on variable factors. Such control and operation have not been entirely satisfactory. One objection to rapid opening of a motorized valve controlling the flow of steam into a building heating system is the noise that customarily results from hammer in the pipes and conduits and, more seriously, damage to traps, valves, fittings and other components of the installation.

It is, therefore, one of the principal objects of the invention to provide a fluid flow control system in which a main motorized valve is opened slowly and closed quickly; that is to say, it is opened at a rate requiring as long as about ten minutes for complete opening and closes in about ten seconds or less. More particularly, the invention contemplates a combination of a motorized or fluid actuated main valve and a vernier throttle valve through which fluid from the diaphragm chamber of the main valve is released to effectuate slow, gradual opening of such main valve at a predetermined rate. More specifically the invention contemplates the connection of the diaphragm chamber of the main valve to the vernier throttle valve for opening or to a source of fluid under pressure for closing.

Another object is to provide a system of the character mentioned wherein the high pressure fluid for actuating the motorized valve is derived from the controlled fluid source. As a refinement of this aspect of the invention, the fluid discharged from the diaphragm chamber of the motorized valve is released into the fluid system on the use or low pressure side of the motorized valve. By this arrangement eflicient over-all operation is achieved, since there is no waste or loss of fluid from the system, this being another object of the invention. As a variation of the arrangement wherein the actuating fluid for the motorized valve is discharged into the use side of the main conduit or pipe, and as a further object of the invention, provision is made for controlling the opening of the motorized valve by the back pressure prevailing in the low pressure use conduit of the system.

In the arrangement contemplated by and as an objective of the invention the flow of actuating fluid to and from the motorized valve is governed by a pilot valve which itself is responsive to the fluid pressure prevailing in the pipe or conduit connected to the low or discharge side of the motorized valve. In such case the fluid actuated pilot valve functions as a three-way monitor valve, optionally connecting the diaphragm chamber of the motorized valve to either a source of high pressure fluid or to discharge. In a specialized version of this aspect of the invention a throttle valve is interposed between the diaphragm chamber of the main valve and the pilot valve whereby it is feasible to regulate the rate at which the fluid enters and leaves the diaphragm chamber and obtain both slow opening and slow closing of the motorized valve. A one-way valve in a bypass provided around the throttle valve modifies the combined pilot valve throttle valve system for either fast closing, slow opening or fast opening, slow closing, depending upon whether the by-pass is set for free flow toward the main valve diaphragm chamber or away from such chamber. The system of the present invention also lends itself to other variations such as opening of the main valve at one rate and closing it at another by connecting one throttle valve in the fluid supply conduit leading to the monitor valve and another throttle valve in the conduit connecting the monitor valve to discharge or to the motorized valve chamber, these additional features also being objectives of the invention.

The drawing represents a system for controlling the flow of steam from a suitable high pressure supply source to a use at lower pressure. This system represents the best known mode of practicing the invention and, although it is described in connection with the control of the flow of heating steam into a heating installation of a building, it is obvious that other applications of the fundamental principles of the invention can be made.

The FIGURE is a layout of the parts and connections of a fluid flow control system showing the control fluid received from the main fluid source and returned to the main fluid body on the use side of the motorized main valve, showing the use of a bypass around the throttling escape valve, embodying the slow opening and dead ending closing principles of the present invention, and show ing a fluid actuated pilot valve and a metering or throttling valve in the control fluid supply line, certain of the components being shown in section and others being represented diagrammatically.

The present control system is intended primarily for use in regulating the flow of fluid such as steam from a source such as a boiler or steam plant to a use such as the heating system of a building.

Main supply conduit 1 carries steam or other fluid from a source, not shown, the flow being from left to right through a main or motorized valve V and into a service pipe or conduit 3 which extends to the building heating system or other using instrumentality.

The valve V is of conventional construction being opened by a helical coil compression spring 8 and closed by fluid pressure acting on a flexible diaphragm 9. For purposes of illustration certain parts of the valve V and of the other valves herein described are shown rotated about the axis of the particular valve from their actual positions so as to appear in the plane of the drawing.

The main or motorized valve V comprises a body or casing 10 the interior of which is divided by a partition 3 11 into a fluid receiving chamber 12 and a fluid discharging chamber 14.

The inlet and outlet openings communicating with the

valve chambers

12, 14 are formed in

circular end flanges

15, 16 by means of which the valve body is attached as by bolts to flanged fittings 90 on the ends of the supply and use pipes 1, 3. The partition separating the

chambers

12, 14 is formed with a threaded opening which receives an annular valve seat element engaged by a valve body or disk 18 to seal the opening in the partition.

The valve disk 18 is carried on the upper end of a stem 19 which is guided in a gland or sealing assembly 20 in head 21 of a yoke 22. The yoke head 21 seals the lateral opening into the discharge chamber 14 of the casing body through which the stem 19 extends into such chamber. An axial pin secured to the sealing disk 18 is guided for sliding movement in a central Opening of a spider formed integrally on the annular valve seat element to locate and align the sealing disk 18 relative to the valve seat.

At the end of the main valve stem 19 opposite the sealing disk 18 is secured a pressure distributing head 24 which is engaged by flexible main valve actuating diaphragm 9. This circular diaphragm is peripherally clamped between circularly flanged end 25 of the yoke 22 and a circular surface portion of hollow head 26 secured to the yoke end 25 by bolts or cap screws. The head member 26 is formed with a concave surface which underlies the main actuating diaphragm 9 in the provision of fluid tight chamber 30 into which fluid under pressure is admitted to react against the diaphragm in actuating the main valve stem 19 to force sealing disk 18 against the seat in the main valve partition. The head member 26 is formed with an internal chamber or water bottle 91 that is continuous with the diaphragm chamber 30 or communicates with the latter through an opening 92 in that portion of the upper wall of the head member that defines the diaphragm chamber.

Normally the main valve stem 19 is biased downwardly as by a helical coil compression spring 8 to move the closure disk 18 away from the valve seat and thereby open a passage through the valve partition for free flow of fluid from the high pressure receiving chamber 12 on the supply side of the main valve to the outlet or low pressure chamber 14 on the use side of the main valve. The compression spring 8 surrounds the valve stem 19, the lower end of the spring reacting against the pressure distributing head 24 on the bottom end of the stem 19 and the upper end of the spring reacting against the end wall of a hollow cylindrical housing extension of the yoke end 25. Such extension constitutes an enclosure for the spring and the end of the extension is formed with an opening through which the stem 19 has a sliding fit. A pair of pins 93 fast in the stem head 24 are guided in apertures in the yoke head 25 and prevent rotation of the stem during axial shifting of the latter in opening and closingv the main valve V.

To close the motorized valve V and stop the flow of fluid from the supply pipe line 1 to the service or use pipe line 3, fluid under pressure is introduced into the chamber 30. Acting against the diaphragm 9 and the stem head 24 the fluid in the diaphragm chamber 30' shifts the stem 19 axially or upwardly to move the closure disc 18 against the valve seat 17. The opening in the partition 11 of the valve casing 10 is thereby sealed to arrest the flow of fluid from the supply to the use sides of the motorized valve V. In this closing of the motorized valve V, the force exerted on the stem head 24 by fluid in the diaphragm chamber must be suflicient to overcome the force exerted on the closure disc 18 by. fluid in the supply chamber 12 of the valve casing 10 as well as the force exerted by the spring 8. Furthermore, the diaphragm 9 pressure against the stem head 24 must be continued as long as the valve is to remain closed since the fluid pressure in the chamber 12 on the supply side of the valve partition continuously augments the force exerted against the diaphragm 9 by the compressed spring 8.

The motorized valve V is capable of being adjusted automatically to vary the opening in the partition separating the inlet and outlet chambers 12, 14- so that exactly the right amount of fluid is passed through the valve from the supply to the use side to satisfy demand as transmitted to the valve by a suitable sensing and controlling system. In closed position against the seat in the partition of the valve the closure disk 18 must withstand the net force exerted thereon by the fluid on one side in the inlet chamber 12 and on the other side in the outlet chamber 14. Additionally the biasing force of the spring 8 must be overcome in retaining the sealing disk 18 in closed position. Movement of the sealing disk 18 to and retention in closed position against the force of fluid pressure in the inlet chamber 12 and against the force of the spring 8 is effected by fluid pressure force acting against the flexible diaphragm 9, the latter pressing against the head 24- of the stem.

Fluid under pressure is supplied to the diaphragm chamber 30 of the motorized or main valve V from a suitable source, which may be a pressurized tank, a city water supply system or the high pressure fluid supply pipe 1, as shown. The high pressure fluid is conducted through relatively small diameter pipe 83 to an adjustable pressure throttling or metering valve T and from the latter through a relatively small diameter conduit or pipe to inlet chamber 96 of an adjustable pilot valve P. This pilot valve governs the disposition of high pressure control fluid received through the throttling valve T and the conduit 95 for closing the main valve. The throttling valve T comprises a body 51 into which are screwed the threaded ends of the high pressure fluid supply pipe 83 and the conduit 95 that leads to the pilot valve P. The hollow interior of the throttle valve body is divided into receiving and discharge chambers 53, '54 by an integral metal partition formed with a threaded aperture into which is screwed a seat member 55 formed with an elongated passage of tapering cross section. Tapered end 56 on threaded adjusting rod 57 is projected into or retracted from the tapered passage of the seat member 55 to vary the flow through the valve. The rod 57 is screwed through bonnet or cap 58 of the valve T, a suitable packing gland 59 being provided to seal the rod in the bonnet, and the rod is movable axially in effecting desired shifting of the needle end portion 56 in the correspondingly tapered passage of the seat member 55. By manually adjusting the position of the needle in the seat member, the rod being provided with a cross arm 60 for use in turning the rod to make such adjustment, the rate at which fluid escapes through the valve T can be regulated as desired. The rate at which fluid is released into the motorized valve to open the closure disc 18 against the spring 8 is governed by the throttle valve T'. A low angle of taper is used in the passage through the seat member '55 and on the adjusting needle 56 so that the throttle valve T can be finely adjusted and set to provide a very slow rate of fluid flow into the diaphragm chamber 30 of the motorized valve. A small diameter tube or pipe line 97 is connected to the use pipe '3 on the low side of the main valve V as by a T fitting 98 and extends to cap of the pilot valve P, a shutoff valve 99 being interposed so that the pilot valve can be readily disconnected for service and repair. The cap 100 of the pilot valve and casing 101 of such valve have matched peripheral surfaces which cooperatively clamp the circular periphery of a flexible diaphragm 102 which reacts against head 103 on stem 104 to shift the latter axially against the biasing force of a helical coil compression spring 105. The stem 104 has a valve body or plug 106 on its lower end, the valve body being tapered and movable axially throughan opening in the partition of casing 107 of the pilot valve. This casing defines the chamber 96 which receives high pressure fluid through the small diameter supply tube or pipe 95, defines also a discharge chamber 108 connected to the use pipe 3 through the discharge or waste conduit 84 with an interposed monitor M, to be later described, and defines an intermediate chamber 109 connected through a conduit 111 and interposed throttling valve T (which is the same as the throttling valve T previously described) to the water bottle and the diaphragm chamber 30 of the main motorized valve V. The diaphragm chamber 30 is connected by parallel paths to the conduit 84 leading to the use conduit 3 on the low pressure side of the main valve V. One path comprises the conduit 111 in which the throttle valve T is inserted; the other path comprises conduit 86 in which a one-way check or by-pass valve 87 is inserted. As indicated by the arrow on the diagrammatic representation of the one-way valve 87, such valve permits substantially free flow of fluid from right to left but prevents flow of fiuid from left to right. Accordingly, no fiow occurs under any condition from the diaphragm chamber 30 of the main valve to the use or low pressure conduit 3 through the by-pass path which includes the valve 87. Furthermore, even when the monitor exhaust or outlet valve 120 and the pilot valve P are open, fluid flows over the escape path from the diaphragm chamber 30 of the main valve V to the use conduit 3 only when the pressure in the latter is lower than that in the diaphragm chamber and only at such rate as the throttle valve T permits. By varying the position of the tapered valve body 166 in the opening of the partition that separates the intermediate chamber 109 of the pilot valve from the exhaust chamber .103 of such pilot, there is effected a regulation of the rate at which control fluid escapes from the pilot valve to waste or exhaust, as will appear.

The pilot valve diaphragm casing part 161 is formed with an integral yoke 114 which at its lower end is secured to the main casing 167 of the pilot valve and is bored to receive slidingly the stem 104. The compression spring 105 surrounds the stem 104 in coaxial relation and is contained in a cylindrical housing 115 located between the yoke arms and screwed into a central opening in the casing part 101, the force in the spring being ad justable by a plug 116 screwed into the open lower end of the housing 115.

The pipe 97 is threaded into a tapped boss in the cap member .100 of the pilot valve so that diaphragm chamber 118 of the pilot valve is in direct communication with the use pipe 3 and such diaphragm chamber is at all times at the same pressure as the use pipe of the system being controlled. The spring 105 is adjusted so that the plug valve 106 seats to seal the intermediate chamber 109 from exhaust at the maximum pressure desired in the use pipe 3.

To open the motorized valve V and supply steam or other fluid from the pipe 1 on the high pressure side of the valve to pipe 3 on the low presure side thereof, control fluid pressure in the diaphragm chamber 30 is reduced by exhausting fluid through the throttle valve T and the pilot valve P, exhaust or discharge chamber 108 of the latter being connected through a small diameter tube 119, a monitor valve M and a tube 84 to the use pipe 3.

Energization of solenoid coil 42 of the monitor valve M is effected in any suitable manner satisfying the control requirements of the fluid system in which the invention is employed. When used to control the supply of heating steam to a building the present system may, in an elementary form, employ a remotely situated manual electric switch for energizing the solenoid 42. To provide automatic control, however, the monitor M is actuated in response to a sensing element such as thermostat 62 located at a suitable point in the building so as correctly to interpret the true demands of the building for heating as represented by the temperature of the ambient air to which the thermostat is exposed. The thermostat, of the bimetallic type, is connected through conventional components so as to connect the solenoid 42 in circuit with a suitable power source to be energized thereby when the temperature of the thermostat drops below the lower limit of the temperature range for which it is set and to open the circuit and de-energize the solenoid when the thermostat is subjected to a tem perature above the upper limit of its setting. A suitable thermostat circuit is illustrated diagrammatically in the drawing, it being understood that other conventional sensing or thermostatic devices and circuits can be used. In the example shown the terminals of the thermostat 62 are connected by wires 63, 64 to

terminals

65, 66 of a relay unit contained in box 67. This relay box contains a stepdown transformer 68 which reduces conventional ll0-volt alternating current power supplied by lines 70, 71 through switch 72 to a lower voltage such as 24 volts that supplies the circuit for the thermostat 62 One terminal of the secondary of the transformer 68 is connected to the box terminal 66 and thus to one side of the thermostat through the wire 64. The other side of the transformer secondary is connected to the box terminal 65 through solenoid coil 73 of a thermostat relay which has an armature 74 spring biased away from

contacts

75, 76. One side of the electromagnetic solenoid coil 42 of the monitor valve M is connected to the power service line 71 through one pole of switch 72 and a wire conductor 77, one side of the primary of the thermostat transformer 68 being also connected to the service line 71 through a branch of the wire conductor 77. The other terminal or side of the monitor solenoid 42 is connected to the other service line 70 through the

relay contacts

75, 76, the contact 75 being connected to such solenoid by wire 78 and the contact 76 being connected by wire 79 to the other pole 'of the switch 72. A branch of the wire 79 is connected to the other terminal of the thermostat transformer primary to complete the circuit through the latter.

When the thermostat circuit is connected to the electric energy source by closing the switch 72, the

relay contacts

75, 76 remain open so long as the thermostat remains above the temperature for which it is set. Upon cooling of the thermostat to a temperature below its lower setting, the thermostat terminals close automatically, completing the circuit through the secondary of the transformer 68 and energizing the relay coil 73 so that the armature 74 is moved across the

contacts

75, 76 This closing of the

relay terminals

75, 76 connects the wires 78, 79 to feed the coil 42 and the monitor valve is thus energized from the electrical power source to shift the armature 43 and thereby to raise lever 44 against the biasing force of gravity or a spring, not shown. This lever is pivoted at 45 to the valve casing 46 and acts against the stem on valve body to open the latter. Spring 121 normally biases the valve body 120 to sealing position against a seat in the partition which separates receiving chamber 122 of the monitor M from discharge chamber 123 of such monitor. The slow opening of the valve B has numerous benefits, particularly in the control of heating fluid to a use system. In the case of a steam heating system, slow opening of the main valve V minimizes radiator hammering and other lso-called warming up noises. The elimination of hammering in the heating system components reduces maintenance and repair costs. The tendency of an intermittent steam heating system to override the desired upper temperature limit is minimized with attendant economy. The system operates free of trouble for long periods of time and obtains smooth and uniform heating of the building.

The exhaust chamber 108 of the pilot P is connected by conduit or tube 119 to the receiving chamber 122 of the monitor, and the discharging chamber of the latter is connected to the waste conduit 84 that leads to the 7 low pressure use pipe line 3. Thus in the normal close condition of the monitor M, its actuating solenoid 42 being unenergized, the exhaust chamber 108 of the pilot P is effectively sealed and, whether the passage between the pilot valve chambers 1G8, 109 be open or closed, the release of fluid from the diaphragm chamber 30 of the main valve V is prevented and the main valve remains closed. Economical operation is achieved by such positive closing of the main or motorized valve V, a so-called dead ending of the supply, when the system demand for the controlled fluid ceases. In the case of the steam heating system mentioned, the demand for heating fluid ends when the thermostat 62 reaches its upper temperature setting. At such temperature the bimetallic element of the thermostat opens the connection between the wires 63, 64, thereby de-energizing the relay coil 73 with the result that the armature 74 is shifted by its biasing spring to open the

contacts

75, 76 and de-energize the solenoid 42 of the monitor valve M. Thereupon the armature 43 of the monitor shifts by gravity or spring action to close the monitor M. Thus the monitor M constitutes a dead ending device functioning to maintain positive valve closing fluid pressure in the diaphragm chamber of the main motorized valve except in response to a demand transmitted by the remote sensing element or thermostat.

The inlet chamber 96 of the pilot P, having at all times an open connection through the throttle valve T to the fluid supply pipe 1 on the high pressure side of the main valve V, continuously supplies pressurized fluid to the intermediate chamber 109 of the pilot P, the valve body 106 of the pilot having a guiding pin which projects loosely into the passage through which the inlet chamber 96 communicates with the intermediate chamber 109. The clearance around such guide pin keeping the intermediate chamber 109 in continuous communication with the inlet chamber 96.

When the pressure in the use pipe 3 is above the balance pressure to which the spring 105 of the pilot P is adjusted, such fluid pressure is transmitted through the tube 97 and the open valve 99 to the control diaphragm chamber 118 of the pilot and acts on the diaphragm 102 to move or hold the valve stem 104 downwardly against the biasing force of the adjusting spring 105 and the fluid pressure in the intermediate chamber 109 to seal the latter from the exhaust chamber 108. The sealing of the outlet from the intermediate chamber 109 to the exhaust results in maintaining or building up fluid pressure in the intermediate chamber 109 which, as previously mentioned, is in continuous communication with the high pressure fluid supply line and receives pressurized fluid from the latter whenever the pressure in the inlet chamber 96 of the pilot is below the pressure which prevails in the supply pipe 1. Fluid pressure thus built up in the pilot valve intermediate chamber 109 is transmitted over the path comprising the conduit 111 and the inserted throttle valve T and also over the parallel by-pass path comprising the tube 86 and the one-way valve 87 tothe casing member 26 of the main valve and the diaphragm chamber 30 of such main valve. The thermostat 62 and related components constitute a primary control over the main valve V, since they govern both the opening and closing of the main valve. The throttle valve T and the parallel one-way bypass valve 87 constitute a secondary control over the main valve V, since they govern only the closing of the main valve. However, the opening of the main valve in response to demand sensed by the thermostat 62 is dominated by the throttle T and bypass 87, comprising the secondary control, since such secondary control at all times prevents opening of the main valve whenever the fluid pressure in the use conduit 3 exceeds the setting of the main valve V, and, if such main valve be already open, eflects closing of the main valve upon increase in fluid pressure in the use pipe 3 above the setting of the main valve.

Thus in a use situation wherein high pressure fluid is to be supplied in response to more than one condition, the arrangement provides secondary opening control of the main valve V servient to the use pressure of the fluid as such pressure exists in the conduit 3 in addition to primary control over both opening and closing of the main valve V by the thermostat 62 and related components.

The overriding of the primary thermostatic control by the secondary control through the exhaust fluid conduits is effective, of course, without the by-pass path 86 and the latter together with its one-way valve 87, may be eliminated so that the only path between the diaphragm chamber 30 of the valve V and the use pipe 3 is through the throttle valve T. In such an arrangement the time rate of both opening and closing of the main valve V is governed by the throttle T.

The pilot P constitutes a secondary dead ending control with respect to both opening and closing of the main valve V, primary control being effected by the monitor M and its related sensing element or thermostat control circuit. Accordingly to effect opening of the main valve V, not only must the monitor valve M be opened by a demand for fluid transmitted through the circuit of the sensing element 62 in order to allow control fluid to escape, but the pilot P must also be open to allow flow of control fluid from the diaphragm chamber 30 of the main valve to exhaust. If either the monitor M or the pilot P closes in response to existence of the condition by which it is satisfied, the escape of control fluid from the relief tube system of the main valve diaphragm chamber 39 is terminated and the main valve is closed by the build up of pressure of the fluid supplied from the high pressure pipe 1. Such closing of the main valve V is at a rate determined by the setting of the supply throttle T. Thus the valve T can be finely adjusted to obtain any desired slow closing rate, a closing by fluid supplied through the throttle valve T and taking as long as fifteen minutes being useful in some applications and, of course, a longer closing period is feasible if desired.

Even though the throttle T be adjusted for slow closing of the main valve V, the arrangement, provides for fast closing of the main valve V in the event the pressure in the use conduit 3 rises above the balance pressure for which the main diaphragm spring 8 is adjusted. For example, if the pilot P fails for any reason to close the passage between the discharge and intermediate chambers 108, 109 in the casing 107, and the monitor M also remains open, the fluid pressure prevailing in the use pipe 3 is transmitted through the open pilot and monitor valves and the parallel paths 86 and 111 to the diaphragm chamber 30 of the main valve, thereby effecting closing of the main valve.

In responding to a demand for fluid or steam starting from a condition in which the main valve V is held closed by the pressure of control fluid in the diaphragm chamber 30, the control system opens the main regulating valve V by relieving the control fluid pressure through the pilot P and the control M valves. In thus responding to a demand the system does not positively shut off the supply of high pressure control fluid but merely opens the exhaust passages, it being understood that such exhaust passages through the pilot and monitor valves and the connecting tubes are large enough to accommodate or carry off without objectionable build up of back pressure the normal flow of control fluid into the inlet chamber 96 of the pilot P at all normal settings of the feed throttling valve T and also to accommodate or carry off fluid released from the diaphragm chamber 30 in allowing the main valve V to open.

The throttle T regulates the slow opening rate of the main motorized valve V. For example, the adjustment of the exhaust throttling valve T may establish an opening rate requiring as much as about ten or fifteen minutes for full opening of the main valve. In this connection it is to be noted that the one-way valve 87 in the by-pass line 86 prevents 'fiuid flow from left to right, as viewed in the figure, thereby restricting the release of control fluid from the diaphragm chamber 30 to the path provided by the tube 111 in which the escape throttle valve T is inserted. The by-pass 87 is efiective, however, in obtaining fast closing of the main valve V, since control fluid is permitted to by-pass the escape throttle valve T in flowing toward the diaphragm chamber 30. With the throttle T in the tube 111 thus controlling the opening rate and the feed throttle T thus controlling the closing rate of the main valve V, it is feasible to adjust the system for both slow opening and slow closing, the opening being at a different rate than the closing and the closing rate being either slower of faster than the opening. The -by-pass path 86 and the one-way valve 87 may be eliminated, in which case the rate of both opening and closing of the main valve V is determined by the setting of the throttle T in the tube 111 unless the throttle T is set at a slower rate than the throttle T in which case the throttle T governs the clos- The invention thus provides a fluid flow control system and a method of controlling the operation of a motorized flow regulating valve which is characterized by slow opening of the valve and closing either rapid or slow as desired. Positive dead ending of the escape of control fluid is provided so that the flow regulating valve is securely closed under predetermined conditions. By employing a fluid motor valve as the main flow regulating device, in combination with such dead ending of the control fluid circuit under shutdown conditions, the invention obtains the advantages of force multiplication in keeping the motorized valve closed to insure against leakage of the high pressure fluid to the use side.

In accordance with the patent statutes the principles of the present invention may be utilized in various ways, numerous modifications and alterations being contemplated, substitution of parts and changes in construction being resorted to as desired, it being understood that the embodiment shown in the drawings and described above and the particular method set forth are given merely for purposes of explanation and illustration without intending to limit the scope of the claims to the specific details disclosed.

What we claim and desire to secure by Letters Patent of the United States is:

1. In a fluid flow control system having a pipe in through which a fluid medium is received under pressure,

automatic control apparatus for regulating the flow of the medium through the pipe line,

said regulating apparatus comprising in combination a motorized valve connected in said pipe line,

said valve having a fluid actuated closing operator,

means acting constantly on the valve biasing it to open position, a throttle valve adjustable to regulate fluid flow therethrough, a pilot valve having an internal fluid cham- 'ber,

means connecting the throttle valve between the operator of the motorized valve and the chamber of the pilot valve,

means connecting the pilot valve chamber to a fluid pressure source,

the pilot valve having an outlet vent for venting the chamber and a closure therefor,

means responsive to the pressure of fluid in the pipe line on the outlet side of the motorized valve actuating the pilot valve closure to close the pilot outlet vent above and open it below a predetermined pressure, the means connecting the pilot chamber to the source including means restricting the rate of flow of fluid to the pilot chamber to less than the rate of flow through the open vent, the pilot closure in conjunction with the actuating means therefor being adapted to vary the rate of fluid flow through the open vent and the fluid pressure in the pilot chamber available to the operator,

a monitor connected to the pilot valve outlet vent to govern the venting of fluid from the pilot valve chamber,

and means responsive to predetermined conditions either automatically opening the monitor for venting of the pilot valve chamber when the outlet of the pilot is open to thereby vent the operator of the motorized valve through the throttle valve for relaively slow bias opening of the motorized valve at a rate determined by the throttle valve adjustment or automatically closing the monitor positively to pre vent venting of the pilot valve chamber and the operator of the motorized valve to thereby apply and maintain fluid pressure on the operator of the motorized valve from said source and keep closed the motorized valve regardless of the condition of the pilot valve, and

the closing of the pilot valve by said pressure responsive means preventing venting of the operator of the motorized valve to keep closed the latter regardless of the condition of the monitor.

2. In a fluid flow control system having a pipe line through which a fluid medium is received under pressure, automatic control apparatus 'for regulating the flow of the medium through the pipe line, i said regulating apparatus comprising in combination a motorized valve connected in said pipe line, said valve having a fluid actuated closing operator, means acting constantly on the valve biasing it to open position,

a one way valve,

a throttle valve adjustable to regulate fluid flow therethrough,

a pilot valve having an internal fluid chamber,

means connecting the one way valve and the throttle valve in parallel relation between the operator of the motorized valve and the chamber of the pilot valve with the one way valve conducting from the pilot valve to the motorized valve,

means connecting the pilot valve chamber to a fluid pressure source, the pilot valve having an outlet vent for venting the chamber and a closure therefor,

means responsive to the pressure of fluid in the pipe line on the outlet side of the motorized valve actuating the pilot valve closure to close the pilot outlet vent above and open it below a predetermined pressure, the means connecting the pilot chambe to the source including means restricting the rate 0f flow of fluid to the pilot chamber to less than the rate of flow through the open vent, the pilot closure in conjunction with the actuating means therefor being adapted to vary the rate of fluid flow through the open vent and the fluid pressure in the pilot chamber available to the operator,

a monitor connected to the pilot valve outlet vent t govern the venting of fluid from the pilot valve chamber,

and means responsive to predetermined conditions either automatically opening the monitor for venting of the pilot valve chamber when the outlet of the pilot is open to thereby vent the operator of th motorized valve through the throttle valve for relatively slow bias opening of the motorized valve at a rate determined by the throttle valve adjustment r automatically closing the monitor positively to prevent venting of the pilot valve chamber and the operator of the motorized valve to thereby apply and maintain fluid pressure on the operator of the motorized valve from said source "and keep closed the motorized valve regardless of the condition of the pilot valve,

the closing of the pilot valve by said pressure responsive means preventing venting of the operator of the motorized valve to keep closed the latter regardless of the condition of the monitor, and the one way valve allowing rapid fluid flow from the pilot valve chamber and the said source around the throttle valve to the operator of the motorized valve for for rapid closing of the latter when either the pilot valve or the monitor is closed.

3. In a fluid flow control system having a pipe line through which a fluid medium is received under pressure,

said valve having a fluid actuated closing operator,

means acting constantly on the valve biasing it to open position,

a first throttle valve adjustable to regulate fluid flow therethrough,

a pilot valve having an internal fluid chamber,

means including a second throttle valve connecting the pilot valve chamber to a fluid pressure source to sup ply fluid to the pilot chamber at a predetermined rate,

means responsive to the pressure of fluid in the pipe line on the outlet side of the motorized valve actuating the pilot valve closure to close the pilot outlet vent above and open it below a predetermined pressure,

the pilot closure in conjunction with the actuating means therefor being adapted to vary the rate of fluid flow through the open vent and the fluid pressure in the pilot chamber available to the operator,

and means responsive to predetermined conditions either automatically opening the monitor for venting of the pilot valve chamber when the outlet of the pilot is open to thereby vent the operator of the motorized valve through the first throttle valve for relatively slow bias opening of the motorized valve at a rate determined by the first throttle valve adjustment or automatically closing the monitor positively to prevent venting of the pilot valve chamber and the operator of the motorized valve to thereby apply and maintain fluid pressure on the operator of the motorized valve from said source,

whereby the operator closes the motorized valve at a rate determined by the rate of the second throttle valve and keeps such motorized valve closed regardless of the condition of the pilot valve, and the closing of the pilot valve by said pressure responsive means preventing venting of the operator of the motorized valve to keep closed the latter regardless of the condition of the monitor.

4. In a fluid flow control system having a pipe line through which a fluid medium is received under pressure,

the motorized valve and the chamber of the pilot valve with the one way valve conducting from the pilot valve to the motorized valve,

means including a second throttle valve connecting the pilot valve chamber to a fluid pressure source to supply fluid to the pilot chamber at a predetermined rate,

whereby the operator closes the motorized valve at a rate determined by the rate of the second throttle valve and keeps such motorized valve closed regardless of the condition of the pilot valve,

the closing of the pilot valve by said pressure responsive means preventing venting of the operator of the motorized valve to keep closed the latter regardless of the condition of the monitor, and the one way valve allowing rapid fluid flow from the pilot valve chamber around the throttle valve to the operator of the motorized valve at a rate determined by said throttle in the source connection for positive closing of the motorized valve when either the pilot valve or the monitor is closed.

5. In a fluid flow control system having a pipe line through which a fluid medium is received under pressure,

automatic control apparatus for regulating the flow of the heating medium through the pipe line,

said valve having a fluid actuated closing operator,

means acting constantly on the valve biasing it to ope position,

a first throttle valve adjustable to regulate fluid flow therethrough,

a pilot valve having an internal fluid chamber,

means including a second throttle valve connecting the pilot valve chamber to the pipe line on the inlet side of the motorized valve to supply fluid to the pilot chamber at a predetermined rate,

the pilot closure in conjunction with the actuating means therefor being adapted to vary the rate of 13 fluid flow through the open vent and the fluid pressure in the pilot chamber available to the operator, a monitor connected to the pilot valve outlet vent to govern the venting of fluid from the pilot valve cham- 1361', g and means responsive to predetermined conditions either automatically opening the monitor for venting the pilot valve chamber when the outlet of the pilot is open to thereby vent the operator of the motorized valve through the first throttle valve for relatively slow bias opening of the motorized valve at a rate determined by the first throttle valve adjustment or automatically closing the monitor positively to prevent venting of the pilot valve chamber and the operator of the motorized valve to thereby apply and maintain fluid pressure on the operator of the motorized valve from said source,

whereby the operator closes the motorized valve at a rate determined by the rate of the second throttle valve and keeps such motorized valve closed regardless of the condition of the pilot valve, and the c108- ing of the pilot valve by said pressure responsive means preventing venting of the operator of the motorized valve to keep closed the latter regardless of the condition of the monitor.

6. In a fluid flow control system of the type comprising a motorized valve having inlet and outlet sides and adapted to be connected in a pipe line for regulating the flow of a fluid medium through the line, said valve comprising means providing a connecting passage between the inlet and outlet sides, a valve seat surrounding such passage, and a valve body, the valve body being mounted for movement toward and away from the seat with the pressure of fluid on the inlet side tending to move the seated body away from the seat, means acting constantly biasing the valve body away from the seat toward open position, and a fluid actuatable closing operator for moving the valve body toward and against the seat, a pilot valve having an internal fluid chamber, means connecting the pilot chamber to a source of high pressure fluid and to the valve closing operator, the pilot valve havin an outlet vent from its chamber and a valve closure therefor, means connected to the outlet side of the motorized valve and responsive to the pressure of fluid on such outlet side to actuate the closure to close the vent above and open the vent below a predetermined pressure, the means connecting the pilot chamber to the source including means restricting the rate of flow of fluid to the pilot chamber to less than the rate of flow through the open vent, the pilot closure in conjunction with the actuating means therefor being adapted to vary the rate of fluid flow through the open vent and the fluid pressure in the pilot chamber available to the operator, a monitor comprising an electric valve connected directly to the pilot chamber vent and governing the release of fluid from the outlet vent of the pilot valve chamber in overriding relation to the valve closure, and means responsive to one predetermined condition adapted automatically to open the electric valve for venting of the pilot valve chamber when the valve closure is open and responsive to another predetermined condition to close the electric valve and positively prevent such venting to thereby maintain fluid pressure in the pilot chamber substantially at a maximum from said source and on the motorized valve operator and keep closed the motorized valve regardless of the condition of the pilot valve, the closing of the pilot valve outlet vent by the pilot valve closure upon actuation by said pressure responsive means preventing venting of the motorized valve operator through the pilot valve chamber to keep closed the motorized valve regardless of the condition of the monitor.

7. In a fluid flow control system as claimed in claim 6, a metering valve interposed in the connecting means between the pilot chamber and the operator of the motorized valve, said metering valve being adjustable to alter the flow rate of fluid between the pilot chamber and such operator, and means providing a one way bypass for fluid around said metering valve permitting fluid flow therethrough toward and preventing fluid flow therethrough from the operator of the motorized valve.

8. In a fluid flow control system as claimed in claim 6, the means connecting the pilot chamber to a pressure source comprising a conduit connected to the inlet side of the motorized valve, and a discharge conduit connected between the monitor and the outlet side of the motorized valve, said discharge conduit constituting the sole path for fluid vented from the pilot valve chamber.

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