US3857410A

US3857410A - Switching valve

Info

Publication number: US3857410A
Authority: US
Inventors: A Bedo; E Beck
Original assignee: SNO TRIK Co
Current assignee: SNO TRIK Co
Priority date: 1973-05-07
Filing date: 1973-05-07
Publication date: 1974-12-31
Anticipated expiration: 1991-12-31

Abstract

A switching valve for high pressure environments in selectively controlling fluid flow between three or more fluid passages included in the valve. The valve includes a body having a bore extending therethrough, a portion of the bore defining a valve chamber having opposed valve seats disposed at each end thereof. An elongated operating stem includes a valve plug at one end thereof for selective reciprocal movement in the chamber to block fluid flow through one of the seats and into or out of the chamber. The first fluid passage extends through the valve body into the bore adjacent one of the valve seats, the second fluid passage extends through the valve body into the chamber and the third fluid passage extends into the bore adjacent the other of the valve seats. In one end position of the stem, fluid flow is permitted between the first and second passages while in the other end position of the stem, fluid flow is permitted between the second and third fluid passages. For manual operation, a new stem design protects the integrity of the stem seals during assembly and disassembly of the valve and the valve seat disposed in the lowermost end of the bore is reversible and easily removable to provide a longer effective life therefor.

Description

United States Patent [191 Bedo et al.

[ Dec. 31, 1974 1 SWITCHING VALVE [75] Inventors: Alfred Bedo, Walton Hills; Edward Beck, Cleveland Heights, both of Ohio [73] Assignee: Sno-Trik Company, Solon, Ohio [22] Filed: May'7, 1973 21 Appl. No.: 357,558

[52] US. Cl 137/625.27, 251/214, 277/112 [51] Int. Cl. Fl6k 11/04 [58] Field of Search..... 137/625.27, 329.03, 625.65, 137/625.25, 392.02, 243.3, 331, 270;

[56] References Cited UNITED STATES PATENTS 1,995,395 3/1935 Mohr 251/214 X 2,123,814 7/1938 Summers 137/625.27 2,154,477 4/1939 Sinclair l37/625.27 X

2,260,523 10/1941 Henry 137/625.27 2,883,145 4/1959 Sage 251/214 X 3,233,863 2/1966 Bowen et a1..... 251/214 X 3,237,917 3/1966 Kunzer et a1. 251/214 3,529,805 9/1970 Callahan, Jr. et a1 251/214 X 3,727,631 4/1973 Suezawa 137/625.27

Primary ExaminerMartin P. Schwadron Assistant Examiner-Robert J. Miller Attorney, Agent, or FirmFay & Sharpe 5 7 ABSTRACT A switching valve for high pressure environments in selectively controlling fluid flow between three or more fluid passages included in the valve. The valve includes a body having a bore extending therethrough, a portion of the bore defining a valve chamber having opposed valve seats disposed at each end thereof. An elongated operating stem includes a valve plug at one end thereof for selective reciprocal movement in the chamber to block fluid flow through one of the seats and into or out of the chamber. The first fluid passage extends through the valve body into the bore adjacent one of the valve seats, the second fluid passage extends through the valve body into the chamber and the third fluid passage extends into the bore adjacent the other of the valve seats. In one end position of the stem, fluid flow is permitted between the first and second passages while in the other end position of the stem, fluid flow is permitted between the second and third fluid passages. For manual operation, a new stem design protects the integrity of the stem seals during assembly and disassembly of the valve and the valve seat disposed in the lowermost end of the bore is reversible and easily removable to provide a longer effective life therefor.

13 Claims, 7 Drawing Figures SWITCHING VALVE BACKGROUND OF THE INVENTION This invention pertains to the art of valves and more particularly to switching valves.

The invention is particularly applicable to switching fluid flow for controlling check or safety valves in high pressure environments such as oil wells and the like and will be described with particular reference thereto; however, it will be appreciated by those skilled in the art that the invention has broader applications and may be used in other environments where use of switching valves for controlling fluid flow are particularly desired.

Prior switching valves of this type have generally comprised complex structures requiring substantial initial expense. Because of the complexity of such prior switching valves, undesired premature valve failure have oftentimes been a problem inasmuch as they added further expense by way of maintenance and/or replacement costs. Also, prior valves of this type in which an elongated valve stem has been employed to effect valve switching have not provided means for the integrity of the stem sealing arrangement when the stem was passed therethrough during valve assembly and disassembly. Likewise, prior valves of this type have not been particularly reliable for continuous use in high pressure environments.

The present invention contemplates a new and improved arrangement which overcomes these problems and others and provides a new switching valve particularly adapted for use in high pressure environments which is simple, economical, reliable and readily adaptable to use in various different applications and for either manual or automatic switching.

The principal object of the present invention is the provision of a new switching valve which is simple in design and operation.

Another object of the present invention is the provision of a new switching valve particularly adapted for use in high pressure fluid systems.

Another object of the present invention is the provision of a new switching valve which is adaptable for either manual or automatic energization.

Still another object of the present invention is the provision of a new switching valve having at least one of the valve seats which is reversible.

Yet another object of the present invention is the provision of a new switching valve which includes a stemdesign for protecting the integrity of the stem sealing medium during assembly and disassembly of the valve.

Yet a further object of the present invention is the provision of a new switching valve having a high degree of reliability during continuous high pressure usage.

A further object of the present invention is the provision of a new switching valve which may be operated as either a normally open or normally closed valve.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, there is provided a valve for controlling fluid flow between three or more separate flow passages. The valve structure has a valve body including an elongated bore extending therethrough, a portion of the bore defining a generally cylindrical valve chamber. First and second axially aligned valve seats, including fluid openings therethrough, are disposed in the bore adjacent one end thereof to define first and second axially spaced ends of the chamber. A first fluid flow passage extends between the exterior of the valve body and the side wall of the bore adjacent the first end, a second fluid flow passage extends between the exterior of the valve body and the side wall of the valve chamber and a third fluid flow passage extends between the exterior of the valve body and the side wall of the bore adjacent the second end. A valve operating stem extends axially into the valve chamber through the first valve seat and the stem is dimensioned so as to provide a substantial flow area through the first valve seat into the chamber about the stem. The valve stem further includes a valve plug disposed in the chamber adjacent the end of the stem and comprises a unitary body having opposed, generally conically shaped end portions and a cylindrical center section with the diameter of the center section being greater than the diameter of the flow openings in the first and second seats. Means are included for selectively reciprocating the stem between a first position with a valve plug in a fluid flow blocking relationship with the fluid flow passage of the first seat to permit fluid flow between the second and third fluid flow passages and a second position with the valve plug in a fluid flow blocking relationship with the fluid flow passage of the second seat to permit fluid flow between the first and second fluid flow passages. The valve also includes a sealing structure, a packing nut and a liner sleeve disposed in the other end of the bore from the chamber which accommodate the reciprocating means and provide a fluid seal therefor.

In accordance with another aspect of the present invention, the reciprocating means comprises a handle having a shaft extending through the packing nut to be threadedly received on the inside of the liner sleeve. The connection between the stem and shaft permit relative rotation therebetween whereby as the stem is threadedly moved relative to the liner, the stem only realizes reciprocating movement between the first and second positions.

In accordance with another aspect of the present invention, the reciprocating means comprise power means selectively energizable to move the stem between the first and second positions. In this instance, the stem is threadedly mounted to the power means within the liner sleeve.

In accordance with still another aspect of the present invention, the second valve seat is included in a member which is selectively removable from within the bore at the one end of the valve body. This member is reversible for reinsertion into the bore so as to present another second valve seat.

In accordance with still another aspect of the present invention, there is provided a new valve stem having a dimensional configuration of a type which protects the integrity of the sealing medium. When using this new stem, the valve may be assembled or disassembled by having the stem pass through the sealing mechanism out of the third fluid passage without stretching or otherwise undesirably deforming the medium.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part thereof and wherein:

FIG. 1 is a partial cross-sectional view of a manually operated switching valve incorporating the concepts of the invention;

FIG. 2 is an enlarged view of a portion of the valve of FIG. 1 showing particularly the inner workings of the valve itself;

FIG. 3 is an enlarged view of the valve plug in one operative position;

FIG. 4 is an enlarged view of the valve plug in the other operative position;

FIG. 5 is an enlarged view of the operating valve stem;

FIG. 6 is a partial cross-sectional view of a second embodiment of the subject invention employing automatic energization means; and,

FIG. 7 is an enlarged view of a portion of the inner workings of the valve shown in FIG. 6.

Referring now to the drawings wherein the drawings are for purposes of illustrating the preferred embodiment of the invention only and not for purposes of limiting means, the FIGURES show a valve body A, valve workings B and a valve operator C. Certain of the component structures employed in practicing the present invention are shown in the commonly assigned US. Pat. No. 3,679,169, which showings and teachings are incorporated herein by reference.

More specifically, and with principal reference to FIGS. 1 and 2, the valve body includes a generally elongated body portion 10 having a top end 12, a bottom end 14 and continuous side wall 16. Extending longitudinally through body 10 is a bore having various diameter portions axially spaced therealong for reasons which will hereinafter become apparent. A portion of bore 20 adjacent bottom end 14 acts to define a valve chamber 22 having first valve seat 24 and a second valve seat 26 which are opposed to and axially spaced apart from each other in order to define the ends of chamber 22.

Extending through the valve body is a first fluid flow passage 30 communicating with bore 20 on the other side of first valve seat 24 from chamber 22. A second fluid flow passage 32 extends through the valve body into the valve chamber itself and finally, a third fluid flow passage 34 extends through the valve body at bottom end 14 on the other side of second valve seat 26 from chamber 22. Protruding outwardly from side wall 16 at the exit area of

passages

30,32 are outwardly threaded

members

36,38 respectively adapted to receive conventional fluid couplings or fittings thereon in order that the valve may be conveniently incorporated into a fluid system. These threaded members also include conventional openings (not shown) therein for receiving the ends of tubing for coupling purposes. Inasmuch as these features are known and do not form a part of the present invention, they are not discussed in detail herein. Bore 20, adjacent bottom end 14, includes an enlarged threaded area 42 adapted to receive a threaded fitting 44. This fitting includes an outer threaded end similar to the arrangement of

members

36,38 which is also employed for receiving conventional couplings or fittings. Although the valve body could be constructed from several materials, an austenitic stainless steel is preferred.

Second valve seat 26 is included in a separate second seat member 50 having opposed frusto-conical ends 52,54 and a generally cylindrical center portion 56. A fluid opening 58 connects ends 50,54 and the end face of each end comprises a separate second valve seat. Thus, this arrangement facilitates ready replacement of the second valve seat by merely reversing the position of second seat member as will hereinafter be more fully described. Although the seat member may be comprised of any number of materials without departing from the intent and scope of the invention, austenitic stainless steel is particularly preferred. To accommodate and properly locate one of frusto-conical ends 52,54 relative to the valve body, there is provided a frusto-conical area 60 connecting enlarged threaded area 42 of bore 20 and valve chamber 22. Likewise, threaded fitting 44 includes an inwardly extending chamber to closely receive the other of the frusto conical ends 52,54 and the generally cylindrical center portion 56 of the seat member.

Adjacent first valve seat 24, bore 20 has a smaller diameter portion extending a short axial distance and which then expands into a slightly larger diameter por tion 72 to define a sealing medium receiving area. Adjacent the end of this larger diameter portion and spaced toward top end 12 is an outwardly flaring or frusto-conical surface portion 74 which then is connected to an even larger, partially threaded packing nut receiving portion 76. The effect and use of

bore portions

70,72, 74 and 76 will become apparent hereinafter.

Disposed within bore 20 for selective reciprocation therein to effect the switching operation of the valve is a valve operating stem generally designated in FIG. 1. FIGS. 2 and 5 show the stem in greater detail and as comprising a unitary structure having an enlarged mounting portion 92, an intermediate portion 94 and a valve plug 96. Disposed between mounting portion 92 and intermediate portion 94 is a first connecting portion 98 and disposed between intermediate portion 94 and valve plug 96 is a second connecting portion 100. In the embodiment of the present invention here under discussion, the diameters of the connecting portions are less than the diameter of

portions

92,94 and plug 96. Valve plug 96 includes opposed conical ends 102,104 connected by a generally cylindrical center portion 106. The two conical portions, in conjunction with

seats

24,26 effect the desired switching during valve operation as will become apparent. In this embodiment of the present invention, enlarged stem mounting portion 92 comprises a generally spherical configuration having a reduced diameter area or band extending generally centrally therearound. Also, the diameter of intermediate portion 94 is at least equal to the greatest cross-sectional dimension of spherical arrangement 108 to receive the desired operating stem properties. Although a martensitic stainless steel stem construction is preferred, other materials may be employed without departing from the scope and intent of the invention.

Disposed in larger diameter sealing medium receiving portion 72 is a seal washer 120. This washer is generally annular shaped having an outside diameter slightly less than the diameter of bore 72 and an inside diameter slightly in excess of the outside diameter of stem intermediate portion 94. A sealing member 122 is received in bore 72 adjacent washer 120. In the preferred embodiment of the invention, this member is manufactured from glass filled TEFLON, is generally annular shaped and has an outside diameter slightly less than the diameter of bore 72 with an internal diameter slightly larger than the outside diameter of stem intermediate portion 94.

An alignment bushing 124 includes a forward portion 126 having an outside diameter slightly less than the diameter of bore 72 and an internal passageway having a diameter slightly in excess of the outside diameter of stem intermediate portion 94. The'alignment bushing also includes a flange portion 128 defining a thrust surface 130 which lies in a plane generally transverse to the axis of bore 20. Flange portion 128 is connected to forward portion 126 by a generally frusto-conical surface 132. In the preferred embodiment of the invention, seal washer 120 and alignment bushing 124 are constructed from stainless steel; however, it will be appreciated that other materials may be employed.

A packing nut 140 having a generally cup-like configuration is received in enlarged diameter portion 76 of bore adjacent top end 12. Specifically, this nut includes an outer peripheral surface 142 having a plurality of threads 144 extending axially therealong over a portion thereof from the open end toward the closed or top wall 146. Threads 144 engage corresponding threads extending inwardly along bore 76 from top end 12. The packing nut includes a passageway 148 extending through top wall 146 and the top wall itself defines an internal shoulder 150. Packing nut 140 includes the conventional external hex configuration which is adapted to be engaged by a tool or other suitable instrument for purposes of rotating the packing nut relative to the valve body. The lower extremity of the packing nut, that is, the open end of the cup-like configuration, defines a driving surface which lies in a plane generally parallel to .alignment bushing thrust surface 130. A keeper 152 suitably operates against the outer hex configuration in order to retain the nut in position. The keeper thus prohibits undesired rotation of the packing nut in a manner once the required compressive force has been applied to sealing member 122.

Disposed within the packing nut and cooperating therewith is a liner sleeve 160. This liner sleeve includes a bore 162 including a plurality of threads 164 spaced axially therealong from the uppermost end toward the lowermost end. The liner sleeve is generally cylindrical and is adapted to be received within packing 140 with the uppermost end portion of the sleeve engaging shoulder 150 of the nut. The very precise packing nut and liner sleeve structure, as well as means for venting fluid leakage past the sealing member will be appreciated from the teachings of the US. Pat. No. 3,679,l69, the teachings of which are incorporated herein by reference.

An actuating stem or shaft 170 having a conventional handle 174 is provided for operating the valve. This stem or shaft includes threads disposed partially therealong which are adapted to mate with threads 164 of liner sleeve 160 as will hereinafter be more fully described. Disposed on the other end of actuating stem 170 from handle 174 is an enlarged actuating stem receiving portion 178 including a stem receiving and mounting area 180 therein. A retaining ring 182 is employed to lock mounting portion 92 of operating stem 90 in position in area 180 to eliminate axial movement between the two stems while permitting relative rotation between them. The specifics of the mounting arrangement, particularly area 180, may be more readily seen from the teachings of the US. Pat. No. 3,679,169.

In the embodiment of the invention under discussion, liner sleeve is constructed from brass or other similar material and the packing nut and actuating stem or shaft are constructed from stainless steel. Such an arrangement tends to. reduce galling of the threaded connection between the stem and packing nut under high pressure conditions although it will be appreciated that other materials could be employed.

Valve body 10 may be conveniently located to a base plate 190 or the like by bolts 192,194 as is also deemed conventional.

In operation and with the valve conveniently mounted to a base portion 190 by, for example, bolts 192,194 and the necessary fluid lines connected to

passages

30,32 and 34, there are two primary or end positions for valve plug 96 to effect the switching operation. The first position shown in FIG. 3, with conical end 102 closely received against first valve seat 24, permits fluid flow only between second and third

fluid passages

32,34. By rotating handle 174 to threadedly advance stem or shaft relative to liner sleeve 160, valve plug 96 is moved toward the second position shown in FIG. 4. In this position, conical end 104 engages second valve seat 26 to permit fluid flow only between first and

second passages

30,32. Return to the first position is effected by threadedly retracting stem 170 relative to the liner sleeve. The connection between actuating stem or shaft 170 and operating stem 90 is such that the rotating movement of the actuating stem encountered during its threaded movement causes only reciprocating movement of operating stem 90. This, of course, is because of the particular connection between stems 90,170. It is important that the valve plug does not rotate during switching between the end positions in order to preserve the integrity of

seats

24,26.

A particularly advantageous use for the subject switching valve, and merely by way of example only, is in oil well safety valve applications. In such applications, a ball check or safety valve is disposed at the base of the oil well shaft itself. This ball check or safety valve is in a normally open position in order that petroleum from the well may flow outward therefrom for normal recovery. To operate the ball check valve using the switching valve of the subject invention, fluid flow passage 30 is connected to a high pressure fluid source. Fluid flow passage 32 is then connected by remote fluid circuit with the ball check or safety valve and fluid flow passage 34 is connected to exhaust. When the oil well is operating normally, the switching valve plug is maintained in the first end position with conical end 102 blocking fluid flow between the first fluid flow passage 30 to second fluid flow passage 32. If, however, the well should catch on fire or it be otherwise desired to shut off the flow of petroleum upward through the well, the valve plug is moved to the second end position wherein conical end 104 engages second valve seat 26 so as to block fluid flow between

passages

32,34 and permitting flow between

passages

30,32. The fluid under high pressure from a source (not shown) passes through passage 30 to passage 32 and then downwardly into the well, thence overcoming any force maintaining the ball check or safety valve in an open condition in order to close that valve. This closing thereby shuts off the petroleum flow to preserve petroleum in the well from loss and, in the case of a fire, eliminates the fuel source as the fire burns itself out.

If the second valve seat should become worn during continuous operation, it is merely necessary to remove threaded fitting 44 from its threaded connection with the valve body, remove second seat member 50 from the body, turn it around and reinsert it in order to present a new second seat. This, of course, makes the valve more versatile in not having to replace a separate seat member each time the second seat becomes worn.

When it is desired to replace or otherwise remove operating stem 90 from the valve, it is merely necessary to remove packing nut 140 and liner sleeve 160 from their threaded association with the valve body. Thereafter, retaining ring 182 may be removed from stem 170 so that operating stem 90 and actuating stem 170 may be separated similar to the manner explained in US. Pat. No. 3,679,169. Once the two stems are separated, operating stem 90 may be pulled outwardly through bore 20 from bottom end 14. Reassembly of the valve is then performed in an opposite manner to that just hereinabove described for disassembly. It should be noted here that stem intermediate portion 94 acts to protect the integrity of sealing medium. As the operating stem is removed from or inserted into the valve, spherical arrangement 108 normally has a tendency to slightly temporarily deform the sealing medium, that is, sealing member 122 on its passage therethrough. Because of this deformation, there is a possibility that fluid leaks could result so that fluid is permitted to undesirably pass between the stern and sealing medium. Although means are provided to handle a small amount of such leakage inherent when using such sealing mediums, any increase in the leakage can affect valve effectiveness. However, with intermediate stem portion 94 of the present embodiment being at least the same cross-sectional dimension as the largest crosssectional dimension of spherical arrangement 108, this particular problem is overcome. Further, intermediate portion 94 has an axial length at least sufficient to be in continuous contact with seal washer 120, sealing member 122 and alignment bushing 124 during valve operation to assure good sealing.

An alternative arrangement to that hereinabove described with reference to FIGS. lis the arrangement shown in FIGS. 6 and 7 for a power activated valve. Inasmuch as substantially all the component parts of the FIGS. 6 and 7 embodiment are identical to the FIGS. 1-5 embodiment, identical numerals with a prime suffix will be employed with new parts or components having new numerals. In this arrangement, operating stem 90' includes a generally hexagonal center portion 200 to facilitate ease of stem removal as will hereinafter become apparent. Although valve plug 96' is substantially identical with valve plug 96, in this second embodiment, operating stem 90' has an operating stern shaft 202 of a constant cross-section. Adjacent the other end of the stem shaft from the valve plug is a threaded area 204 for connecting the operating stem to actuating stem 170. Liner 160 includes an enlarged stem receiving portion 206 at the base of actuating stem or shaft 170 which, in turn, is connected to valve operator C. Threaded portion 204 is closely threadedly received in receiving portion 206 but in this embodiment no relative rotation is permitted between stems 90', 170'. Stem 170' includes a conventional connection generally designated 208 to a pneumatic drive valve generally designated 212 which may be energized as desired in order to switch the operating stern and valve plug between the first and second end positions. Drive valve 212 may, of course, be energized from a remote station if so desired. Inasmuch as when using this arrangement actuator stem 170 only received reciprocal movement, it is not necessary to include that structure facilitating relative rotational movement between stems 170 and in order to protect the valve seats during valve operation. Although a pneumatic drive valve 212 energizing arrangement has been disclosed, it will be appreciated by others skilled in the art that alternative drive mediums may be employed without departing from the intent and scope of the present invention.

When it is desired to remove operating stem 90' from association with the valve body, it is merely necessary to first remove threaded fitting 44' and second seat member 50' from their association with the valve body as hereinabove described. Since the valve plug includes a generally hexagonal center portion 200, it is then merely necessary to insert a wrench into the longitudinally extending bore 20 and turn the stem to release it from its threaded connection with member 206. Reassembly of the stem into the valve is accomplished in an opposite manner from that just described with reference to disassembly.

It should be recognized that the valve hereinabove described is not intended to be limited in scope of usage. Thus, the valve may be used as either normally open or normally closed in order to effect the desired switching in any type of high pressure fluid environment.

The invention has been described with reference to the preferred embodiment. Obviously, modifications and alterations will occur to others upon the reading and understanding of the specification. It is our intention to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Having thus described our invention, we now claim:

1. A switching valve for controlling fluid flow between three separate fluid flow passages, said valve comprising:

a valve body including an elongated bore extending therethrough, a portion of said bore adjacent one end thereof defining a generally cylindrical valve chamber;

first and second axially aligned valve seats including fluid openings therethrough disposed in said bore to define first and second axially spaced ends for said chamber;

a first fluid flow passage extending between the exterior of said valve body and the side wall of said bore adjacent said first end;

a second fluid flow passage extending between the exterior of said valve body and the side wall of said valve chamber;

a third fluid flow passage extending between the exterior of said valve body and the side wall of said bore adjacent said second end;

a valve operating stem extending axially into said valve chamber through said first valve seat, said stem being dimensioned to provide a substantial flow area through said first valve seat and into said chamber about said stem, said valve stem further including a valve plug disposed in said chamber adjacent the end of said stem, said valve plug comprising unitary body having opposed, generally conically shaped end portions and a cylindrical center section being greater than the diameter of the fluid openings of said first and second seats;

means for selectively reciprocating said stem between a first seated position with said valve plug in a fluid flow blocking relationship with the fluid opening of the first seat to permit fluid flow between said second and third fluid flow passages and a second seated position with said valve plug in a fluid flow blocking relationship with the fluid opening of said second seat to permit fluid flow between said first and second fluid flow passages,

a sealing washer received in said bore on the other side of said first fluid passage from said first valve seat, said washer having a bore therethrough slightly larger than the diameter of said stem;

a sealing member closely received over said stem and spaced outwardly along said bore adjacent said sealing washer;

a bushing received oversaid stern and spaced outwardly along said bore adjacent said sealing memher;

a packing nut threadedly received in said bore adjacent the other end thereof from said bore one end, said nut adapted to contact said bushing and to apply a compressive force to said sealing member; and,

a liner sleeve disposed in said packing unit, said liner sleeve housing the connection between said operating stem and said reciprocating means.

2. The valve as defined in claim 1 wherein said reciprocating means comprises a handle including a shaft extending through said packing nut with said shaft being threadedly received on the inside of said liner sleeve, said connection permitting relative rotation between said shaft and stem, whereby as said stem is threadedly moved relative to said liner, said stem substantially only realizes reciprocating movement between said first and second positions.

3. The valve as defined in claim 2 wherein the end of said shaft includes means defining an inwardly extending stem receiving area with said stem including a generally spherical mounting area at its outermost end, said stem receiving area being dimensioned to receive said mounting area in a rotatable relationship relative thereto and to prevent axial movement between said stem and said shaft.

4. The valve as defined in claim 3 further including releasable means for retaining said spherical mounting area in said stem receiving area.

5. The valve as defined in claim 3 wherein said stem includes said spherical area at one end, said valve plug at the other end and an intermediate working portion disposed therebetween, said intermediate portion having a cross-sectional dimension at least as large as the diameter of said stem mounting area.

6. The valve as defined in claim 5 wherein said stern further includes connecting portions disposed between said intermediate portion and said stem mounting area and between said intermediate portion and said valve plug, said connecting portions having cross-sectional dimensions less than said intermediate working portions with said intermediate portion having an axial length sufficient to permit continuous engagement with said sealing washer, sealing member and bushing during travel of said stern between said first and second positions.

7. The valve as defined in claim 1 wherein said second valve seat is selectively removable from said bore from said one end thereof.

8. The valve as defined in claim 7 wherein said second valve seat comprises a separate seat member having a second valve seat in each end face thereof, said second valve seats in said member being connected by said second seat fluid opening.

9. The valve as defined in claim 1 wherein said reciprocating means comprises power means selectively energizable to move said stem between said first and second position.

10. The valve as defined in claim 9 wherein said power means includes a stem receiving member extending through said packing nut into said liner sleeve with said stem threadedly engaging said stem receiving member at the other end thereof from said valve plug, said valve stem having a substantially constant cross section over the entire length thereof from said valve plug.

11. A switching valve for controlling fluid flow between three separate fluid flow passages, said valve comprising:

a third fluid flow passage extending between the exte rior of said valve body and the side wall of said bore adjacent said second end;

a valve operating stem extending axially into said valve chamber through said first valve seat, said stem being dimensioned to provide a substantial flow area through said first valve seat and into said chamber about said stem, said valve stem further including a valve plug disposed in said chamber adjacent the end of said stem, said valve plug comprising a unitary body having opposed, generally conically shaped end portions and a cylindrical center section with the diameter of said center section being greater than the diameter of the fluid openings of said first and second seats;

means for selectively reciprocating said stem between a first seated position with said valve plug in a fluid flow blocking relationship with thefluid opening of the first seat to permit fluid flow between said second and third fluid flow passages and a second seated position with said valve plug in a fluid flow blocking relationship with the fluid openings of said second seat to permit fluid flow between said first and second fluid flow passages; and,

means for sealing and means for closing the other end of said bore to eliminate fluid flow outwardly of means being housed in said liner sleeve.

12. The valve as defined in claim 11 wherein said reciprocating means extends through said packing nut into said liner sleeve.

13. The valve as defined in claim 12 wherein said reciprocating means is threadedly received in said liner sleeve and said connection facilitates relative rotation between said stem and reciprocating means whereby as said reciprocating means is threadedly moved relative to said liner, only reciprocating movement is transmit-

Claims

1. A switching valve for controlling fluid flow between three separate fluid flow passages, said valve comprising: a valve body including an elongated bore extending therethrough, a portion of said bore adjacent one end thereof defining a generally cylindrical valve chamber; first and second axially aligned valve seats including fluid openings therethrough disposed in said bore to define first and second axially spaced ends for said chamber; a first fluid flow passage extending between the exterior of said valve body and the side wall of said bore adjacent said first end; a second fluid flow passage extending between the exterior of said valve body and the side wall of said valve chamber; a third fluid flow passage extending between the exterior of said valve body and the side wall of said bore adjacent said second end; a valve operating stem extending axially into said valve chamber through said first valve seat, said stem being dimensioned to provide a substantial flow area through said first valve seat and into said chamber about said stem, said valve stem further including a valve plug disposed in said chamber adjacent the end of said stem, said valve plug comprising unitary body having opposed, generally conically shaped end portions and a cylindrical center section being greater than the diameter of the fluid openings of said first and second seats; means for selectively reciprocating said stem between a first seated position with said valve plug in a fluid flow blocking relationship with the fluid opening of the first seat to permit fluid flow between said second and third fluid flow passages and a second seated position with said valve plug in a fluid flow blocking relationship with the fluid opening of said second seat to permit fluid flow between said first and second fluid flow passages, a sealing washer received in said bore on the other side of said first fluid passage from said first valve seat, said washer having a bore therethrough slightly larger than the diameter of said stem; a sealing member closely received over said stem and spaced outwardly along said bore adjacent said sealing washer; a bushing received over said stem and spaced outwardly along said bore adjacent said sealing member; a packing nut threadedly received in said bore adjacent the other end thereof from said bore one end, said nut adapted to contact said bushing and to apply a compressive force to said sealing member; and, a liner sleeve disposed in said packing unit, said liner sleeve housing the connection between said operating stem and said reciprocating means.

6. The valve as defined in claim 5 wherein said stem further includes connecting portions disposed between said intermediate portion and said stem mounting area and between said intermediate portion and said valve plug, said connecting portions having cross-sectional dimensions less than said intermediate working portions with said intermediate portion having an axial length sufficient to permit continuous engagement with said sealing washer, sealing member and bushing during travel of said stem between said first and second positions.

11. A switching valve for controlling fluid flow between three separate fluid flow passages, said valve comprising: a valve body including an elongated bore extending therethrough, a portion of said bore adjacent one end thereof defining a generally cylindrical valve chamber; first and second axially aligned valve seats including fluid openings therethrough disposed in said bore to define first and second axially spaced ends for said chamber; a first fluid flow passage extending between the exterior of said valve body and the side wall of said bore adjacent said first end; a second fluid flow passage extending between the exterior of said valve body and the side wall of said valve chamber; a third fluid flow passage extending between the exterior of said valve body and the side wall of said bore adjacent said second end; a valve operating stem extending axially into said valve chamber through said first valve seat, said stem being dimensioned to provide a substantial flow area through said first valve seat and into said chamber about said stem, said valve stem further including a valve plug disposed in said chamber adjacent the end of said stem, said valve plug comprising a unitary body having opposed, generally conically shaped end portions and a cylindrical center section with the diameter of said center section being greater than the diameter of the fluid openings of said first and second seats; means for selectively reciprocating said stem between a first seated position with said valve plug in a fluid flow blocking relationship with the fluid opening of the first seat to permit fluid flow between said second and third fluid flow passages and a second seated position with said valve plug in a fluid flow blocking relationship with the fluid openings of said second seat to permit fluid flow between said first and second fluid flow passages; and, means for sealing and means for closing the other end of said bore to eliminate fluid flow outwardly of said valve through said bore between said operating stem and reciprocating means, said sealing means comprising a sealing medium received in said bore on the other side of said first fluid passage from said first valve seat and said closing means comprising a packing nut threadedly received in said bore adjacent the other end thereof from said one end, said packing nut adapted to contact said sealing medium and supply a compressive force thereagainst, said packing nut further including a liner sleeve received thereIn, the connection between said operating stem and said reciprocating means being housed in said liner sleeve.

13. The valve as defined in claim 12 wherein said reciprocating means is threadedly received in said liner sleeve and said connection facilitates relative rotation between said stem and reciprocating means whereby as said reciprocating means is threadedly moved relative to said liner, only reciprocating movement is transmitted to said stem.