Excess flow valve with cage

An assembly for limiting excess flow includes a housing having an internal bore that defines a seat. A cage is positioned within the internal bore and includes an upstream end and a sealing surface at a downstream end. A back plate with at least one magnet is seated within the internal bore upstream of the cage. The cage moves away from the back plate when a predetermined flow condition is exceeded such that the sealing surface engages the seat.

BACKGROUND OF THE INVENTION

The present invention generally relates to an excess flow valve that permits fluid flow through a flow line if the flow is below a predetermined flow rate but minimizes the flow if the flow rate rises above the predetermined limit to prevent uncontrolled flow or discharge of fluids.

Excess flow valves are typically used in a capsule to facilitate its installation in various flow lines, fittings, pipe systems, appliances and the like. The excess flow valve acts in response to a high or a low differential pressure between the upstream pressure and downstream pressure of the capsule. In one known configuration, the excess flow valve is comprised of four components including a housing, a seat, a valve plate or body, and a spring or magnet to bias the valve plate. The capsule may be inserted in various flow passageways including a valve body, a connector fitting, a hose fitting, a pipe nipple, a tube, a male iron pipe (MIP), a female iron pipe (FIP), an appliance and other similar installations to provide excess flow protection.

These spring and magnet configurations can be disadvantageous from a cost and assembly perspective due to the number of components. Further, spring operated devices have a tendency to float or close gradually as the internal flow increases right up to the design limit. The tolerances on these designs can have undesirable bypass flow rates when the spring constant changes relative to temperature (primarily on polymeric springs and metal springs in extreme temperatures) and frictional resistance to closing caused by spring buckling on compression springs.

SUMMARY OF THE INVENTION

According to one exemplary embodiment, an assembly for limiting excess flow includes a housing having an internal bore that defines a seat. A cage is positioned within the internal bore and includes an upstream end and a sealing surface at a downstream end. A back plate with at least one magnet is seated within the internal bore upstream of the cage. The cage moves away from the back plate when a predetermined flow condition is exceeded such that the sealing surface engages the seat.

In another embodiment according to the previous embodiment, the cage includes at least one opening from an exterior surface into an interior of the cage.

In another embodiment according to any of the previous embodiments, the sealing surface comprises a curved sealing surface.

In another embodiment according to any of the previous embodiments, the cage defines a central axis extending in a direction of flow through the housing, and wherein the cage includes a plurality of legs extending from the upstream end to the downstream end and which are circumferentially spaced apart from each other about the axis to provide a plurality of openings into the interior of the cage.

In another embodiment according to any of the previous embodiments, the upstream end of the cage includes an open end that is in fluid communication with the plurality of openings, and wherein the downstream end comprises a closed end.

In another embodiment according to any of the previous embodiments, when flow does not exceed the predetermined flow condition, fluid flows through the open end of the cage, through the plurality of openings, and then flows radially outward and around the curved sealing surface to exit a downstream end of the housing.

In another embodiment according to any of the previous embodiments, the back plate comprises a ring-shaped component having a radially outer surface in engagement with the internal bore and a radially inner surface with upstream and downstream end faces extending between the radially outer and inner surfaces. One of the upstream and downstream end faces includes an orifice that receives the magnet.

In another embodiment according to any of the previous embodiments, wherein the cage has an outermost diameter, and wherein the cage is defined by a length extending from the upstream end to the downstream end, and wherein a ratio of the length to the outermost diameter is greater than 1:1. In one example, the ratio is at least 1.6:1.

In another embodiment according to any of the previous embodiments, the cage is comprised of a polymeric material. In one example, the polymeric material includes a predetermined amount of ferromagnetic material.

In another embodiment according to any of the previous embodiments, the seat of the housing has a shape that is different than the curved sealing surface to create a ring of point contact between the curved sealing surface and the seat.

In another embodiment according to any of the previous embodiments, the housing comprises one of a fitting, tube, connector, cartridge, male pipe, or female pipe.

According to another exemplary embodiment, a method of assembling an excess flow valve includes providing a housing, a cage, and a back plate with an orifice for a magnet as described in any of the embodiments set forth above, and inserting the back plate with the magnet and the cage into the internal bore such that the back plate is held fixed relative to the housing, and the cage is capable of moving away from the back plate when a predetermined flow condition is exceeded such that the sealing surface can engage the valve seat.

In another embodiment according to any of the previous embodiments, the back plate and cage are installed into the housing through an upstream end.

In another embodiment according to any of the previous embodiments, the housing with the back plate and cage are installed as an assembly into a downstream end of a secondary housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1shows a fitting10and an excess flow valve12. The fitting10can carry different fluids, such as natural gas, or other gases or liquids for example. In one example configuration, the fitting10is configured to couple a fluid supply line to an appliance (not shown).

The fitting10includes a housing14having an internal bore16extending from an upstream end18to a downstream end20. The bore16provides a seat22for the valve12during an excess flow condition. The internal bore16is defined by at least two inner diameters. There is at least an upstream inner diameter d1 and a downstream inner diameter d2. The upstream inner diameter d1 is greater than the downstream inner diameter d2. The bore16also includes a third inner diameter d3 that is positioned axially between the upstream inner diameter d1 and the downstream inner diameter d2.

A shuttle or cage24is positioned within the internal bore16at the third inner diameter d3. A magnet26is received within an orifice25formed in a back plate34that is positioned upstream of end28of the cage24. The cage24includes a downstream end30that provides a sealing surface32(FIG. 2). In one example, the sealing surface32comprises a curved sealing surface.

The back plate34with the magnet26is seated within the internal bore16upstream of the cage24. The cage24is configured to move away from the back plate34and magnet26when a predetermined flow condition is exceeded such that the curved sealing surface32engages the seat22. This will be discussed in greater detail below.

The housing14defines a central axis A that is concentric with a central axis of the cage24and which extends in a direction of flow F through the housing14. The cage24includes at least one opening38into an interior of the cage24. In one example, the cage24includes a plurality of ribs or legs36that extend from the upstream end28to the downstream end30. The legs36are circumferentially spaced apart from each other about the axis A to provide a plurality of openings38, and are configured to hold the valve12concentrically within the housing14. In one example, the legs36are equally spaced around the axis A (seeFIGS. 2A-2B).

As shown inFIGS. 2-3, the legs36connect the base26to the curved sealing surface32. In one example, the legs36are slightly curved along the direction of flow F to provide a convex radially outer surface40and a concave radially inner surface42. In another example, the inner surface42could be straight, or have a different profile than the outer surface40. The base26includes an open end44. The open end44comprises an inner bore that is in fluid communication with the upstream end18of the housing14. The open end44fluidly connects the upstream end18of the housing14to an internal cavity46of the cage24. The open end44is in fluid communication with the plurality of openings38via the internal cavity46. The downstream end30comprises a closed end that defines the curved sealing surface32.

The cage24and legs36can have different shapes from that which is shown inFIGS. 2, 2A, and 2B.FIGS. 7A-7Bshow an example where a cage124has a downstream end128that is of a generally constant diameter. The upstream end provides a curved sealing surface132similar to that described above. The legs136are spaced about the axis A as described above.

FIGS. 8A-8Bshow an example where a cage224has a curved sealing surface232and an upstream end228having a generally constant diameter. The legs236have a variable thickness in a direction extending along a length of the cage224. The legs also have a variable cross-section as shown inFIG. 8B. Each of these example embodiments operates in the manner described below.

When flow through the valve12does not exceed the predetermined flow condition, the fluid flows through the open end44of the base26and into the internal cavity46. Then the fluid flows between the legs36, through the plurality of openings38, and then flows radially outward and around the curved sealing surface32to exit the downstream end20of the housing14. When flow through the valve12exceeds the predetermined flow condition, the pressure of the flowing fluid exceeds the pull of the magnetic force and the cage24disengages from the back plate34. The cage24moves in a downstream direction until the curved sealing surface32seats firmly against the seat22. This restricts the flow without completely closing, allowing some bypass of flow from exiting the downstream end20of the housing14. The cage24moves back into engagement with the back plate34when pressures upstream and downstream of the cage24equalize.

In one example, the upstream end28of the cage24includes a seat50that is configured to receive a stainless steel hoop ring (not shown) which interacts with the back plate34when the flow does not exceed the predetermined flow condition. In the example shown, the seat50comprises a reduced diameter portion of the upstream end28of the cage24. A flat surface58extends from the outermost diameter of the cage24to the reduced diameter portion. The flat surface58is preferably perpendicular to the central axis A so that the surface58easily aligns with the back plate34. The housing14includes an internal shoulder52that serves to seat the back plate34within the housing14such that the back plate34with the magnet26does not move relative to the housing14.

In one example shown inFIG. 1, the back plate34comprises a ring-shaped component having a radially outer surface54in engagement with the internal bore16and a radially inner surface56with upstream and downstream end faces extending between the radially outer54and inner56surfaces. One of the downstream and upstream end faces includes the orifice25that receives the magnet26. In the example shown inFIG. 1, a single magnet26is inserted in the orifice25on an upstream side of the back plate34. In the example shown inFIG. 3, a plurality of miniature disc magnets26are received within the orifice on a downstream side of the back plate34. In the example shown inFIG. 4, a single magnet26is inserted in the orifice on a downstream side of the back plate34. Other configurations could also be used.

In one example, the downstream end face of the back plate34is in engagement with the end face28of the cage24when flow does not exceed the predetermined flow condition. Optionally, the fitting10may include a stop to hold the cage24from contact with the back plate34and magnet26when in an open position. While one magnet is shown, it should be understood that a plurality of magnets could be utilized to interact with the cage24.

As shown inFIG. 2, the upstream end28of the cage24defines an outermost diameter D of the cage24. The cage24is also defined by a length L extending from the upstream end28to the downstream end30. The length L is greater than the diameter D to prevent binding of the cage24in the housing14. A ratio of the length L to the diameter D is greater than 1:1. In one preferred example, the ratio is at least 1.6:1.

In another example, a ratio of a portion of the cage24that is straight versus a portion of the cage24that is curved is 1:1 or greater. In other words, preferably the straight portion of the cage should be the same or longer than the portion of the cage that is curved.

The cage24is configured to be movable in response to a magnetic force generated by the magnet26that is located within the orifice25of the back plate34. This can be accomplished by forming the cage of various types of material and/or providing a magnetically responsive material on the cage24.

In one example, the cage24is comprised of semi-magnetic material in order to limit the attractive forces to the back plate34and magnet26within the assembly and to provide some environmental corrosion protection. In one such example, the cage24is made from a polymeric material with a predetermined amount of ferromagnetic material as a fill material. In one example, the polymeric material includes a minimum of 5% of stainless steel fiber fill material, the grade of which can be attracted to a magnet.

In another example, the cage24is completely made from a polymeric material and a secondary component, such as a stainless steel hoop ring for example, is assembled on the cage24.

In one example, the polymeric material is a material which has a low coefficient of friction and which is ideally suited for both the operating temperature range and corrosive environment as needed.

In another example, the cage24is made completely from a thin walled stainless steel tube with one closed end. The grade of steel is such that it is capable of being attracted to a magnet.

In order to improve the overall accuracy of the valve12regardless of the mounting position, the weight or mass of the cage24must be kept to a minimum relative to the functional requirements. In order to reduce the tolerance sensitivity at which the cage24separates from the back plate34, the back plate34with the magnet26should be designed to operate in a range where the pull force relative to distance approaches a horizontal line. In one preferred example, a slope of a line tangent to the force-distance curve is less than 45 degrees.

The seat22of the housing14is configured to have a shape that is different than the curved sealing surface32of the cage24to create a ring of point contact between the curved sealing surface32and the seat22. In one example, the nose, i.e. the closed downstream end30, of the cage24is elliptical in form and is larger in size than a downstream opening of the housing14. The shape of the seat22is therefore configured to have a shape that does not match the shape of the nose.

As shown inFIG. 1, the internal bore16is defined by at least two inner diameters. There is at least an upstream inner diameter d1 that seats the back plate34and a downstream inner diameter d2 that defines the seat22for the cage24. The upstream inner diameter d1 is greater than the downstream inner diameter d2. The bore16also includes the third inner diameter d3 that is positioned axially between the upstream inner diameter d1 and the downstream inner diameter d2. The third inner diameter d3 defines a portion of the housing14within which the cage24shuttles back and forth based on the flow condition. The third inner diameter d3 is less that the upstream inner diameter d1 and greater than the downstream inner diameter d2.

In the example shown inFIG. 1, the excess flow valve12is loaded into a fitting10. However, the valve12′ could also be loaded into a flexible connector60as shown inFIG. 4. In this example, the housing that receives the valve12comprises a tube14′. The tube14′ connects a flexible tube portion62to a rigid connector64. The cage24and back plate34with the magnet26are formed as described above. Further, the internal bore16′ of the tube14′ is similarly profiled to that described above.

Thus, the structure that receives the cage24and magnet comprises a housing that can be a fitting, tube, connector, cartridge, male pipe, female pipe, etc.

A method of assembling an excess flow valve12includes providing a housing14, a cage24, and a back plate34with a magnet26as described in any of the embodiments set forth above, and inserting the back plate34with the magnet26and the cage24into the internal bore16such that the back plate34is held fixed relative to the housing14and the cage24is capable of moving away from the back plate34when a predetermined flow condition is exceeded such that the curved sealing surface32can engage the valve seat22.

In one example, the back plate34and cage24are installed into the housing through the upstream end18as shown inFIGS. 1-4.

In another example, the back plate34and cage24in the housing14are installed as an assembly into a downstream end70of a secondary housing72as shown inFIGS. 5-6. In this example, the housing14includes an increased diameter portion74defining an abutment surface76that seats against the downstream end70of the secondary housing72as shown inFIG. 5.

The subject invention offers several advantages over prior designs. The subject invention offers a reduction in components as compared to a four-piece configuration (eliminating a brass fitting, a brass seat, a plate and replacing a plastic housing, for example), resulting in a lower overall cost. Further, the subject invention provides an end-loading magnetic excess flow valve where the components are assembled from the upstream side toward the downstream side of the valve allowing fewer parts as noted above and allowing for an automated assembly processes in manufacturing. As discussed above, components of this valve12can be easily loaded into various different components such as a fitting, a flexible connector (in tube cavity/in connector), a cartridge, etc., or the components can be directly loaded into a male or female pipe, for example.

To allow for bind free movement of the cage24within the fitting or housing14relative to the direction of flow, the geometry of the cage is such that the length L is greater than the diameter D. Further, the end of the cage24is elliptical in form which allows for easy alignment during assembly and provides a face to seal off the flow of the fluid within the line during an excess flow condition.

Further, in order to minimize manufacturing cost, the valve components are configured and positioned within the housing in such a way that the flow of gas or fluid through the assembly at any given point does not exceed the overall flow capacity of the valve by a significant margin. This approach places the flow control on the back plate with the orifice inner diameter at the upstream end of the valve. It also minimizes the size, strength or number of magnets required to auto-reset the valve after an excess flow condition has been repaired.

As discussed above, the subject invention may utilize a plurality of magnets. The magnets and the back plate orifice with the housing can be designed where individual magnets are inserted within a polymeric orifice design which serves to retain the orifice assembly within the housing and properly position the magnets.

Also, the finite ring of contact between the seat and the curved sealing surface could also be made from a resilient material for a version of the valve that allows no bypass flow.