US3128792A

US3128792A - Three-way valve

Info

Publication number: US3128792A
Application number: US201854A
Authority: US
Inventors: Rule Clinton
Original assignee: Atwood and Morrill Co Inc
Current assignee: Atwood and Morrill Co Inc
Priority date: 1962-06-12
Filing date: 1962-06-12
Publication date: 1964-04-14
Anticipated expiration: 1981-04-14

Description

April 14, 1964 c. RULE 3,128,792

THREE-WAY VALVE Filed June 12, 1962 2 Sheets-Sheet l FIG. I

INLET- INVENTOR CLINTON RULE BY r/m V ATTORNEYS April 14, 1964 c. RULE THREE-WAY VALVE Filed June 12, 1962 2 Sheets-Sheet 2 FIG. 2

INVENTOR CLINTON R ULE ATTORNEYS United States Patent 3,128,792 THREE-WAY VALVE Clinton Rule, Beverly, Mass., assignor to Atwood & Merrill C0., Salem, Mass, a corporation of Massachusetts Filed June 12, 1962, Ser. No. 201,854 2 Claims. (Cl. 137-6255) The present invention relates to three-way valves, and more particularly to valves wherein two difierent flow paths from a valve may be controllably selected under high operating pressures.

In such applications as boiler feedwater heater by-pass flow control, it is necessary at times to divert the flow through a bypass passage, while under normal operation the flow is through the heater. It is essential that the transition in ilow be smooth, and with no possibility of inadvertently shutting off the flow through both paths, as could occur if separate valves were incorrectly sequenced. Furthermore, the flow transition must be made at full operating pressures, which may be of the order of 2500 lbs, per square inch. In the larger sizes of valves, this presents a serious difiiculty in terms of power requirements for actuating the valve, as the valve from either position is required to open against the full pressure.

It is therefore an object of the invention to provide a three-way valve which makes possible the selection of flowpaths, the use of a single valve insuring that both paths may not by mistake be simultaneously shut off, and wherein the power requirements for valve actuation, particularly during the initial opening phase, are materially less than would normally be encountered.

In accordance With the foregoing, a feature of the valve of the present invention is the provision of integral pilot valve mechanism, actuated automatically by the same actuating means employed for the main valve, whereby an initial partial opening is provided in the proper direction to reduce the pressure drop across the valve and thereby enable the full opening to proceed against substantially less than the full initial head.

In the drawings illustrating the invention,

FIGURE 1 is a sectional elevation of a three-way valve, showing the valve with one of its outlets closed and the other passage fully open.

FIGURE 2 is a sectional elevation of the valve of FIG- URE l but omitting the actuating mechanism at the top, showing the preliminary opening of the pilot, wave element, and

FIGURE 3 is a view corresponding to FIGURE 2, but with the valve fully closed in the other of its two positions and the flow diverted through the passage that was closed in FIGURE 1.

The valve illustrated in FIGURE 1 comprises a valve body indicated generally at 8 having inlet passage 10 and two

outlet passages

12 and 14. By way of example, one outlet passage may connect with a feedwater heater (not illustrated), while the other outlet discharges into the heater by-pass line. The top of the valve body is closed by a cover plate 16 which carries the driving mechanism 18 for the stem 2i). In the more detailed description which follows, the outlet 12 will at times be referred to as the first outlet and outlet 14 as the second outlet. Outlet 12 is disposed in aligned relation to inlet 10, while outlet 14 is at right angles to the inlet passage.

The valve body is provided with a pair of spaced coaxial .

seat rings

24 and 26, the seat 24 being disposed in outlet passage 14 while seat 26 is mounted in divider partition 28 between inlet 10 and first outlet 12. For convenience of assembly, both seat rings are insertable through the top of the valve body when cover 16 is removed, the seat 26 being threaded into the partition 28 and thereafter secured as by welding to prevent backing out.

The movable valve mechanism which serves to close one or the other of the outlet passages comprises a main poppet valve element 32 and a pilot poppet element 34 within and relatively movable with respect to the main poppet 32. The pilot poppet is secured to the stem 20, while the main poppet valve 32 is slidably mounted on the stem.

The main poppet valve 32 is circular in configuration about the axis of the stem and is provided with axially spaced

circular seats

35 and 36 facing in opposite axial directions. Seat 35 is positioned to engage seat ring 24 when the valve element is in lower closed position (FIG- URE 1), while seat 36 engages ring 26 when the valve is in upper closed position (FIGURE 3).

The main poppet 32 is provided with a central chamber defined by spaced walls 42. The lower wall slidingly engages the reduced lower end portion 44 of the stem 20, While the upper wall is enough to permit passage of the pilot poppet into the main poppet during assembly, after which poppet seat ring 46 is screwed into place and preferably pinned or welded against rotation. Ring 46 is formed with yoke arms 48 carrying a bushing 50 for sliding engagement with the stern 2t). Thus the main poppet is slidingly supported on the stem 20 in two axially-spaced regions for accurate alignment with the seats in the main body. Lateral support for the lower end of the stem is provided by the bearing 52 carried by yoke arms 54 extending in wardly from lower main poppet seat ring 24.

The pilot poppet seat ring 46 and the corresponding region on the inner surface of the lower wall of the main poppet are shaped to provide seats 47 for the pilot poppet in each of its two positions within the main poppet. [Flow communication through the interior of the main poppet valve, when the pilot poppet is unseated, is provided by radial openings 56 around the periphery of the poppet into the central chamber, and thence upwardly between yoke arms 48 above seat ring 46, as Well as downwardly through axial openings 58 in the lower wall inwardly of the lower seating surface for the pilot valve.

To prevent the main poppet 32 from rotating about the valve stem at times when the main poppet is out of contact with either seat, the poppet is keyed to the stem 20. A set screw 62 is secured in the bearing portion of poppet seat ring 46, with the reduced end portion of the screw extending into a slot or keyway 64- in stem 20. Thus a non-rotating sliding connection is provided between stem and main poppet. The stem is prevented from rotating by the provision of a guide member 66 secured to the stem 20 above the cover and slidingly engaging an elongated rib or projection 68 integral with the yoke 70 on which the power actuating means for the stem is mounted.

In the position of the valve illustrated in FIGURE 1, the flow is from inlet 10 to first outlet 12, through the opening between seat ring 26 and valve seat 36. That is, the main poppet is in lowermost position and the pilot poppet is likewise seated against the lower seat within the main poppet. Thus no flow reaches the second outlet 14 and the full pressure difference between inlet 10 and outlet 14 is applied to the area of the main poppet represented by seat ring 24.

To shift the flow from the first to the second outlets, as from feedwater heater to by-pass, or vice versa, the valve stem 20 is slowly raised, either by hand wheel or electric motor 82, through conventional actuating connections to the threaded upper end of stem 20'. The initial upward movement of the stem serves to lift the pilot poppet 34 from its seat within the main poppet, thereby allowing limited flow to take place into the secprovided with an opening large nd outlet 14, as shown in FIGURE 2. By reason of the lesser diameter of the pilot poppet seat as compared with the diameter of the main poppet, the working area exposed to the upstream line pressure is substantially less than that of the main poppet and the initial opening of the pilot valve requires far less force than if the main valve were being opened.

As the pilot poppet moves upwardly from its seat in the main poppet, the flow through

passages

56 and 58 to the second outlet 14 increases, while the main poppet remains seated by reason of the still appreciable drop from inlet 12 to outlet 14. Upon continued upward movement of stem 20, the pilot poppet seats against the upper pilot seat ring 46, with the result that the main poppet is now lifted bodily with the stern and transferred into contact with the upper seat ring 26. Because of the substantial reduction in the pressure differential due to the preliminary or pilot opening of the passage to outlet 14, the main valve may be lifted away from its seat with relatively modest power requirement, comparable to that needed for the initial pilot opening. With the arrival of the main poppet at its uppermost position, the passage to second outlet 14 is now fully open, and that to the first outlet 12 fully closed, as shown in FIGURE 3. During the transition, when the main poppet is in intermediate position between the seats, as in FIGURE 2, the set screw 62 and keyway 64 are effective to prevent spinning of the main poppet on the stem, as might occur in the event of any asymmetry in the flow toward and through the radial passages 56 into the main poppet and then outwardly through the axial ports.

The invention thus comprises a three-way or multiplepath flow selection valve having internal and automatic pilot valving so that the force required to open the valve from either position may be substantially less than that normally required to open a large diameter valve against high working pressures. has been illustrated and described, my invention comprehends other constructions and arrangements in accordance with the terms of the accompanying claims.

I claim as my invention:

'1. A three-way valve comprising a valve body having an inlet and. a pair of outlets, passages in the body from the inlet to each of the outlets, the passages for the outletshaving circular seats facing one another in spaced coaxial relation, a main poppet valve intermediate said seats and having oppositely facing external circular seats aligned with the seats in the outlet passages in the valve body, an axially-movable actuating stem extending from outside the valve body axially through the seat openings in the outlet passages and through the main poppet therebetween, axially spaced bearing means carried by the main poppet in sliding engagement with the stern, bearing means positioned within one of the outlet passages in the valve body in sliding engagement with the stern adjacent the main poppet for centering support of said stem and main poppet, the main poppet having a generally circular chamber within the poppet body, said chamber having axially spaced walls, a pilot poppet within the chamber and secured to the stem, said pilot poppet having oppositely While a particular embodiment facing circular seats, the main poppet having circular seats within the chamber on the opposite axially spaced walls thereof, said seats being aligned with the seats on the pilot poppet and of lesser diameter than the external seats on the main poppet, passages in the main poppet extending intermediate the spaced external seats thereof into the chamber within the poppet for flow communication from valve inlet to poppet chamber, and other passages in the main poppet intermediate the valve stem and the seats for the pilot poppet for flow communication through the chamber past the pilot poppet to a valve outlet when the main poppet is seated on said outlet and the pilot poppet is out of seating engagement with the main poppet.

2. A three-way valve comprising a valve body having an inlet and a pair of outlets, passages in the body from the inlet to each of the outlets, the pasasges for the outlets having circular seats facing one another in spaced coaxial relation, a main poppet valve intermediate said seats and having oppositely facing external circular seats aligned with the seats in the outlet passages in the valve body, an axially-movable actuating stem extending from outside the valve body axially through the seat openings in the outlet passages and through the main poppet therebetween, bearing means positioned within one of the outlet passages in the valve body in sliding engagement with the stern adjacent the main poppet for centering support of said stern and main poppet, the main poppet having a generally circular chamber within the poppet, said' chamber having axially spaced walls, a pilot poppet within the chamber and secured to the stem, said pilot poppet having oppositely facing circular seats, one of the chamber walls having a seat for the pilot poppet and a central bearing in sliding engagement with the valve stem, an aperture in the other wall of the chamber having a diameter greater than the diameter of the pilot poppet, a pilot poppet seat ring secured in said aperture, a bearing carried by the said seat ring and slidably engaging the valve stem in axially spaced relation to the bearing in the first-mentioned wall, said pilot poppet seats in the chamber being aligned with the seats on the pilot poppet, passages in the main poppet extending intermediate the spaced external seats thereof into the chamber within the poppet for flow communication from valve inlet to poppet chamber, and other passages in the main poppet intermediate the valve stem and the seats for the pilot poppet for flow communication through the chamber past the pilot poppet to a valve oulet when the main poppet is seated on said outlet and the pilot poppet is out of seating engagement with the main poppet.

References Cited in the file of this patent UNITED STATES PATENTS 2,624,365 Hesson Jan. 6, 1953 2,657,005 Van Nest Oct. 27, 1953 2,741,264 Leonard Apr. 10, 1956 FOREIGN PATENTS 521,819 Germany Mar. 27, 1931

Claims

1. A THREE-WAY VALVE COMPRISING A VALVE BODY HAVING AN INLET AND A PAIR OF OUTLETS, PASSAGES IN THE BODY FROM THE INLET TO EACH OF THE OUTLETS, THE PASSAGES FOR THE OUTLETS HAVING CIRCULAR SEATS FACING ONE ANOTHER IN SPACED COAXIAL RELATION, A MAIN POPPET VALVE INTERMEDIATE SAID SEATS AND HAVING OPPOSITELY FACING EXTERNAL CIRCULAR SEATS ALIGNED WITH THE SEATS IN THE OUTLET PASSAGES IN THE VALVE BODY, AN AXIALLY-MOVABLE ACTUATING STEM EXTENDING FROM OUTSIDE THE VALVE BODY AXIALLY THROUGH THE SEAT OPENINGS IN THE OUTLET PASSAGES AND THROUGH THE MAIN POPPET THEREBETWEEN, AXIALLY SPACED BEARING MEANS CARRIED BY THE MAIN POPPET IN SLIDING ENGAGEMENT WITH THE STEM, BEARING MEANS POSITIONED WITHIN ONE OF THE OUTLET PASSAGES IN THE VALVE BODY IN SLIDING ENGAGEMENT WITH THE STEM ADJACENT THE MAIN POPPET FOR CENTERING SUPPORT OF SAID STEM AND MAIN POPPET, THE MAIN POPPET HAVING A GENERALLY CIRCULAR CHAMBER WITHIN THE POPPET BODY, SAID CHAMBER HAVING AXIALLY SPACED WALLS, A PILOT POPPET WITHIN THE CHAMBER AND SECURED TO THE STEM, SAID PILOT POPPET HAVING OPPOSITELY FACING CIRCULAR SEATS, THE MAIN POPPET HAVING CIRCULAR SEATS WITHIN THE CHAMBER ON THE OPPOSITE AXIALLY SPACED WALLS THEREOF, SAID SEATS BEING ALIGNED WITH THE SEATS ON THE PILOT POPPET AND OF LESSER DIAMETER THAN THE EXTERNAL SEATS ON THE MAIN POPPET, PASSAGES IN THE MAIN POPPET EXTENDING INTERMEDIATE THE SPACED EXTERNAL SEATS THEREOF INTO THE CHAMBER WITHIN THE POPPET FOR FLOW COMMUNICATION FROM VALVE INLET TO POPPET CHAMBER, AND OTHER PASSAGES IN THE MAIN POPPET INTERMEDIATE THE VALVE STEM AND THE SEATS FOR THE PILOT POPPET FOR FLOW COMMUNICATION THROUGH THE CHAMBER PAST THE PILOT POPPET TO A VALVE OUTLET WHEN THE MAIN POPPET IS SEATED ON SAID OUTLET AND THE PILOT POPPET IS OUT OF SEATING ENGAGEMENT WITH THE MAIN POPPET.