Dual plate check valve

A check valve in which a stop pin assembly is situated so as to prevent the movement of a flapper beyond a predetermined position. In a preferred embodiment the check valve has two flappers with the stop pin assembly situated therebetween to prevent either one of them from pivoting beyond an essentially vertical position. The stop pin assembly is configured such that it can be inserted and locked in place when the check valve is inserted within a valve body that contains the check valve. The stop pin assembly can comprise three elements including a central portion and first and second end portions, although the stop pin assembly could instead comprise a single element. The stop pin assembly is inserted between two holders and in a preferred embodiment is rotatable to a locking position where it is affixed in place by fasteners.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to field of check valves and, more particularly, to a dual plate check valve incorporating a stop pin assembly, with the stop pin assembly preventing valve flappers from pivoting beyond a predetermined position.

2. Description of the Related Art

Check valves are one-way valves that permit a fluid to flow in one direction but not in the other direction. They come in a variety of sizes, shapes, and types and are usually self-controlling, meaning that the flow of the fluid itself will typically control the opening and closing of the check valve. They are often used in systems that utilize pumps to pump the fluid through piping or other similar vessels; a heart valve (natural or man-made) is one example of a check valve.

A certain type of check valve, sometimes referred to as a swing check valve or tilting disc check valve, utilizes one or more movable discs, sometimes referred to as “flappers”, to block the reverse flow of fluids. In a typical arrangement, the flapper is hinged on an axis of some kind, such as a hinge pin. In a two-flapper (dual-plate) arrangement, the hinge pin is centrally located with each flapper pivoting on the hinge pin towards each other like the wings of a butterfly.

SUMMARY OF THE INVENTION

The claimed invention provides a novel structure for a check valve in which a stop pin is situated between two flappers to prevent either one of them from pivoting beyond an essentially vertical position, as described and shown in more detail in connection with the drawings provided herewith. In a preferred embodiment, the stop pin is configured such that it can be inserted and locked in place when the check valve is inserted within a valve body that contains the check valve. In a more preferred embodiment the stop pin comprises three elements comprising a central portion and first and second end portions, although it is contemplated that the stop pin could instead comprise a single element in which the first and second end portions are integrated with the central portion. The stop pin is inserted between two holders and in a preferred embodiment is rotatable to a locking position where it is affixed in place by fasteners.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 5illustrate a preferred embodiment of the claimed invention.FIG. 1is an exploded view of a check valve comprising a valve body1and a disc (flapper) assembly2. The stop pin assembly of the claimed invention is not shown inFIG. 1for sake of simplicity, but is described in detail below. The valve body1has a valve body bore12in which is positioned a seat13. The seat13provides a base against which disc assembly2is placed when inserted within valve body bore12during use. A web14extends diametrically across the valve body bore12and divides the seat13into two halves, each half comprising a flow opening14A corresponding to each of the flappers4, discussed below. Gasket surfaces15and16respectively are at each end of the valve body and provide mounting surfaces for gaskets in a known manner. When the check valve ofFIG. 1is inserted in a pipe, fluid flow would normally be in the upward direction relative toFIG. 1, as indicated by arrow A.

The disc assembly2is shown in more detail inFIGS. 2 and 3. In this embodiment the assembly comprises two substantially semi-circular flappers4(first and second flappers), two holders5(first and second holders), and a hinge pin7(axle pin). In each holder5is an elongated (essentially oval-shaped) bore17, with a longitudinal axis11of elongated bore17being substantially parallel to a longitudinal axis of the valve body1corresponding to the direction of travel of fluid flowing within the check valve. Each end of the hinge pin7is mounted in one of the elongated slots and the flappers4are mounted on the hinge pin7. In this configuration, the flappers4can pivot on hinge pin7, for example, from shown inFIG. 2to the position shown inFIG. 3.

In this embodiment the flappers4are mounted on the hinge pin7using bosses18, as can be best seen inFIG. 3. An outer surface19of each of the holders5is of the same profile as that of the inner surface of the valve body bore12, so that they will fit snugly against the inner surface. In this preferred embodiment the valve body bore12is essentially circular in shape and the outer surface19of the holders5are curved so as to correspond to the essentially circular shape of the valve body bore12.

The disc assembly2is positioned in the bore12by holding the disc assembly2with the flappers4urged towards the open position, as shown inFIG. 1, and inserting the disc assembly2into the valve body bore12, until it is stopped by seat13.

By design, the dual plate configuration shown inFIGS. 1-5contemplates that each flapper4is essentially responsible for blocking or allowing flow through one half of the valve body bore diameter, i.e., each disc is associated with one half of the valve body bore12and with one of the flow openings14A. As shown inFIG. 1, each of the flappers4could theoretically be urged far enough towards the open position such that one of them could move past the vertical position, i.e., one of the flappers4could be moved into a position whereby it impinges on the half of the valve body bore diameter associated with the other flapper4. To ensure that the flappers4do not move such that one of the flappers4moves past the vertical position, a stop pin assembly6is provided. As seen inFIGS. 2-5, the stop pin assembly6is mounted in bores21in the holder5.

FIG. 4shows details of a preferred embodiment of a sub-assembly comprising the hinge pin7, stop pin assembly6, and holders5of the claimed invention, with the flappers4and associated elements (bosses18, spring8) removed for sake of simple explanation. As noted above, in each holder5is an elongated bore17. The elongated bores17permit upward and downward movement of the hinge pin7within the elongated bore17, along the axis of the check valve, to permit the back edges or “heels” of the flappers4to clear the seat13as they rotate to the open position and also back to the closed position.

The stop pin assembly6is designed so that it can be inserted into the holders5, and locked into place, while the disc assembly is sitting inside the valve body1. In a preferred embodiment illustrated inFIG. 4, the stop pin assembly6comprises a three-piece assembly comprising stop pin6A (center element or central pin portion) and two retainer pins9(first and second end elements). A retainer pin bore21is formed through the outer surface of each holder5as shown. The inside diameter of retainer pin bore21is sized so that that a shaft portion of retainer pins9can slide snugly therethrough. In the inner surface of each holder5, a slot22is formed, having a flat-sided top portion22A and a generally circular bottom portion23as shown. In this embodiment, the diameter of the circular bottom portion23is slightly larger than the diameter of retainer pin bore21, so that a head portion of retainer pins9will prevent the retainer pins9from sliding through the retainer pin bore21when the shaft portion of a retainer pin9is inserted through a retainer pin bore21in the holder as shown in the drawing figures. The stop pin6A can have first and second ends with the first retainer pin being positionable adjacent to said first end and said second retainer pin being positionable adjacent to said second end.

To enable the locking of the stop pin assembly6in place in the holders5, each end of stop pin6has flat sides formed as shown, corresponding to the flat sided top portion22A of retainer pins9. In this configuration, when oriented properly, the stop pin6can slide through the flat sided top portion22A and into the circular bottom portion23. Through each flat side of stop pin6is formed a hole or other means cooperating with a fastener10to enable the rotational movement of the stop pin6around its longitudinal axis to be prevented/inhibited. In the preferred embodiment shown in the figures, the hole in each flat side of stop pin6is a threaded hole that has threading matching threading on fastener10, which enables a fastener10to be threaded into each hole. A head portion of fastener10should be sized such that it fits within the flat-sided top portion22A as shown, thereby securing the stop pin assembly in place and preventing it from moving rotationally about its longitudinal axis. In a preferred embodiment, fastener10comprises an allen screw, i.e., a screw having a hexagonal hole in its head for use with a hex or alien wrench. However, it is understood that numerous other fastening means may be utilized to enable the fixing of the stop pin assembly6in place as shown and described, and such alternative fastening means are within the scope of the claimed invention.

To assemble the full disc assembly2into the valve body, the hinge pin7, with the flappers4and spring8situated thereon, is inserted into the elongated bores17of holders5, and then as a group are inserted into the bore to rest on the seat. The retainer pins9are then inserted into bores20of the valve body (only one is visible in the drawing but in a preferred embodiment there is a second one situated 180° from the one shown, to accommodate the second retainer pin9) through the bores21of the holders5until flushed into it. Then, as described below, the stop pin6A is fastened in to complete the disc assembly2.

A step by step procedure of locking the stop pin6A into the holders5is illustrated inFIG. 5. Stop pin6A is inserted through the slots22of the holders5in a way that its flat ends slide through the slots22and come to rest in circular bottom portion23of holders5. Next, stop pin6A is rotated 90° to allow the fasteners10to be screwed into holes24through the slots22, locking the stop pin6A in position. Although not required, a portion of the stop pin6A away from its ends can be formed with flat sides (see center of stop pin6A in the drawing figures) so that a wrench or other device can be secured thereon and torqued to rotate the stop pin6A as described).

As noted above, the elongate bores17permit movement of the stop pin6A, along the axis of the valve, to permit the back edges or “heels” of the flappers4to clear the seat as they rotate to the open position and also back to the closed position. In the event that these bores become worn to an extent that replacement is necessary only the holders5need be replaced, rather than the entire valve.

In general, dual plate check values are made in various grades of ferrous (such as various grades of Carbon and Stainless Steels) and non-ferrous metals, copper alloys, nickel alloys and other such metals depending on the metal compatible/suitable for the various materials (flow media) which flows within the dual plate check valves. Thus, the preferred material to be used depends on compatibility of the flow media. In a preferred embodiment, the internal parts are made of various grades of stainless steels.

Further, non-metals, such as polymers and such advanced engineered and engineering plastics, and ceramics can also be used.

Although the present invention has been described with respect to a specific preferred embodiment thereof, various changes and modifications may be suggested to one skilled in the art and it is intended that the present invention encompass such changes and modifications as fall within the scope of the appended claims. For example, although the stop pin assembly is described and shown as a three piece element, it is contemplated that it could also comprise a single element with the stop pin6A and the two retainer pins9being formed integrally such that they are a single piece. Further, although the valve body bore in which the disc assembly2is inserted is shown as being essentially circular (pipe-shaped) in shape, it is understood that the valve body bore could be essentially any shape, in which case the components of the disc assembly2would merely need to be modified in shape to correspond to the shape of the valve body bore. In addition, although the preferred embodiment described herein uses two bores20corresponding to two retainer pins9, it is understood that the device could instead be designed with a single bore20and a single corresponding retainer pin9and still provide the benefits and functionality described herein.