FIELD OF THE INVENTION

This invention relates to pipe fittings, and more particularly to composite transition fittings.

BACKGROUND OF THE INVENTION

Transition fittings are known in the prior art for fluidly connecting pipes that are made from different materials, such as metallic pipes and polymeric pipes. Transition fittings often incorporate a threaded portion, which may be made from a metal such as brass, and a non-threaded portion, which may be made from a polymeric material. The threaded portion may, for example, be adapted for attaching to a threaded metallic pipe, and the non-threaded portion may, for example, be adapted for attaching to a non-threaded polymeric pipe. When the fitting is installed between a metallic pipe and a polymeric pipe, the fitting allows fluid, such as water, to flow through the fitting from the metallic pipe to the polymeric pipe, or vice versa.

A disadvantage of transition fittings that incorporate metallic components, and in particular brass, is that machined brass components can be very expensive. Furthermore, brass often contains lead, which may leach into the water and potentially cause a health hazard. In addition, fittings that contain dissimilar metallic and polymeric materials may have an increased risk of leaking, due to a number of factors, including the wide spread in coefficients of thermal expansion of the different materials.

Transition fittings that are made from polymeric materials only are also known in the prior art. For example, U.S. Pat. No. 8,172,275 to Sumrall, Jr. et al., issued May 8, 2012, teaches a composite polymeric transition pipe fitting that includes a tubular main fitting body with a secondary tubular polymeric body that is molded into the main body, such that the main body extends around the secondary body.

A disadvantage of the transition fitting disclosed in U.S. Pat. No. 8,172,275 to Sumrall, Jr. et al. is that, because the secondary tubular polymeric body is molded into the main body, the dimensions of the secondary tubular polymeric body are limited by the dimensions of the main body.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved type of pipe fitting that at least partially overcomes some of the disadvantages of the prior art.

Accordingly, in one aspect the present invention resides in a pipe fitting comprising: a first body and a second body that together at least partially define a fluid flow passage; the first body defining a first portion of the fluid flow passage that extends from a first end of the fluid flow passage to a first internal opening; the second body defining a second portion of the fluid flow passage that extends from a second internal opening to a second end of the fluid flow passage; wherein the first body has a first interface surface that surrounds the first internal opening, the first interface surface having a plurality of anti-rotation grooves; wherein the second body has a second interface surface that surrounds the second internal opening and engages with the first interface surface, the first internal opening being in fluid communication with the second internal opening, and the second interface surface having a plurality of anti-rotation fingers that are each received by and engage with a corresponding one of the anti-rotation grooves; and wherein rotation of the second body relative to the first body is resisted by the engagement of the anti-rotation fingers with the anti-rotation grooves.

At least one advantage of the pipe fitting according to at least some embodiments of the present invention is that the anti-rotation fingers and anti-rotation grooves may improve the connection between the first and second bodies, which helps the fitting withstand the rotational forces that may be experienced during installation or removal of the fitting.

Furthermore, in at least some preferred embodiments, the arrangement of the anti-rotation grooves on the first interface surface allows the second body to be overmolded over the first body. This allows the second body to extend away from the first body, and to be formed in a shape that is at least partially independent of the shape of the first body. For example, in some embodiments of the invention, the second body may be formed to incorporate a spigot or a socket, without requiring any corresponding changes to the shape or size of the first body. This increases the number of manufacturing options that are available, and for example would allow a single molded shape of the first body to be used in conjunction with any number of different molds for the second body, providing spigots and sockets of various shapes and sizes.

Preferably, the first body has a cylindrical wall with a cylindrical outer surface and a cylindrical inner surface, and the first interface surface is a ring-shaped end surface of the cylindrical wall that spans between the cylindrical outer surface to the cylindrical inner surface. The cylindrical wall preferably includes an overlapping portion where the second body is overmolded over the first body. The first body also preferably includes a non-overlapping portion which is spaced from the second body. The non-overlapping portion may, for example, include a male or female threaded end portion for threadedly engaging with a threaded attachment, such as a brass pipe or the like.

At least one advantage of the first body having an overlapping portion and a non-overlapping portion is that the non-overlapping portion can be changed without requiring a corresponding change to the shape of the second body. For example, the first body could be formed to incorporate male or female threaded end portions of different sizes, while maintaining the same size and shape of the overlapping portion of the cylindrical wall. This would allow the same mold for the second body to be used in conjunction with any configuration of the first body, thus providing increased options and flexibility during manufacturing.

The cylindrical wall preferably has at least one circumferential groove that extends radially inwardly from the outer circumferential surface, and more preferably at least two circumferential grooves. The second body is preferably overmolded over the circumferential grooves, thereby forming circumferential fingers that extend into and engage with the circumferential grooves. The engagement of the circumferential grooves with the circumferential fingers helps to resist the second body being separated from the first body.

Preferably, at least one of the circumferential grooves carries a resiliently compressible o-ring, which provides a fluid tight seal between the cylindrical wall and the second body. This helps to prevent fluid from leaking out of the fitting through the space between the first body and the second body.

Preferably, the first body is made from a first polymeric material that is suitable for attachment to a metallic pipe, such as glass-filled polyvinylidene fluoride. Also preferably the second body is formed from a second polymeric material that is different from the first polymeric material, such as polymeric materials that are suitable for attachment to a polymeric pipe, including chlorinated polyvinyl chloride.

Preferably, the anti-rotation grooves are oriented in a substantially parallel pattern on the first interface surface.

In some embodiments, the first body has a cylindrical wall with a cylindrical outer surface, a cylindrical inner surface, and a ring-shaped end surface that connects the cylindrical outer surface to the cylindrical inner surface; wherein the cylindrical inner surface defines at least part of the first portion of the fluid flow passage; and wherein the ring-shaped end surface comprises the first interface surface.

Preferably, the cylindrical wall extends concentrically about a central axis; wherein the first internal opening comprises a circular opening; and wherein the central axis extends through a center of the circular opening.

In some embodiments, the end surface, which is preferably ring-shaped, comprises a top surface that is substantially perpendicular to the central axis; wherein each of the anti-rotation grooves has a first side surface, a second side surface, and a bottom surface; wherein the first side surface and the second side surface each extend axially inwardly from the top surface, the first side surface being spaced from and substantially parallel to the second side surface; wherein the bottom surface is spaced axially inwardly from the top surface and extends between the first side surface and the second side surface; and wherein the first side surface, the second side surface, the bottom surface and the groove end surface of each anti-rotation groove defines a groove cavity.

Optionally, the bottom surface of each of the anti-rotation grooves is substantially flat, and substantially parallel to the top surface. The first side surface and the second side surface optionally each have a substantially flat portion. The substantially flat portion of the first side surface and the substantially flat portion of the second side surface may, for example, be substantially perpendicular to the top surface. Optionally, the first side surface and the second side surface each have a rounded transition portion that connects the substantially flat portion to the top surface.

In some embodiments, the first interface surface has a bearing area where the anti-rotation grooves contact with the anti-rotation fingers to resist rotation of the second body about the central axis relative to the first body; wherein the bearing area is related to an expected magnitude of torque applied to the pipe fitting during installation of the pipe fitting according to the following equation: T=C×BA wherein T represents the expected magnitude of torque in pound inches, BA represents the bearing area in square inches, and C represents a constant in pounds per inch; and wherein the constant C is in a range from 2000 pounds per inch to 2400 pounds per inch. Optionally, each of the anti-rotation grooves has a vertical surface area that includes the first side surface and the second side surface; and wherein the bearing area is calculated as 50% of a sum of the vertical surface areas of the anti-rotation grooves. The constant C may, for example, be between 2100 pounds per inch and 2200 pounds per inch, or between 2125 pounds per inch and 2135 pounds per inch, or about 2129.17.

In some embodiments, each of the anti-rotation grooves has a width defined by a distance between the first side surface and the second side surface; wherein each of the anti-rotation grooves has a depth defined by an axial distance of the bottom surface from the top surface; and wherein a ratio of the width to the depth is, for example, in a range from 1.45 to 1.55, or between 1.50 and 1.52, or about 1.516. Optionally, the width of each of the anti-rotation grooves is substantially identical; and the depth of each of the anti-rotation grooves is substantially identical.

In some embodiments, the anti-rotation grooves each extend from the cylindrical outer surface of the cylindrical wall towards a central plane that contains the central axis and is substantially perpendicular to the anti-rotation grooves. The anti-rotation grooves may, for example, each have a groove end surface that extends axially inwardly from the top surface to the bottom surface, and that extends between the first side surface and the second side surface; and wherein the groove end surface of each of the anti-rotation grooves is spaced from the central plane, and spaced from the circular opening. Optionally, the anti-rotation grooves on a first side of the central plane are symmetrical relative to the anti-rotation grooves on a second side of the central plane. Optionally, there are at least 3 and no more than 11 of the anti-rotation grooves on each side of the central plane, or there are at least 5 and no more than 9 of the anti-rotation grooves on each side of the central plane, or there are 7 of the anti-rotation grooves on each side of the central plane. Preferably, the groove end surface of each of the anti-rotation grooves is rounded. The groove end surface of each of the anti-rotation grooves may, for example, be spaced a radial distance from the cylindrical inner surface; wherein the cylindrical wall has a wall thickness defined by a distance between the cylindrical outer surface and the cylindrical inner surface; and wherein a ratio of the radial distance to the wall thickness is greater than 0.3, or between 0.3 and 0.5, or between 0.35 and 0.45, or about 0.395. In some preferred embodiments, the radial distance of the groove end surface of each of the anti-rotation grooves from the circular opening is substantially equal.

Preferably, the second body has a cylindrical extension that extends concentrically about the central axis; and wherein the cylindrical extension has an inner extension surface that engages with the cylindrical outer surface of the cylindrical wall. The cylindrical wall preferably has at least one circumferential groove that extends radially inwardly from the cylindrical outer surface. The cylindrical extension is preferably overmolded over at least a portion of the cylindrical outer surface, including the at least one circumferential groove. The at least one circumferential groove optionally comprises a sealing groove that contains a resiliently compressible o-ring, the o-ring being configured to provide a fluid tight seal between the cylindrical wall and the cylindrical extension. Optionally, the cylindrical extension has a circumferential finger that extends radially inwardly from the inner extension surface; wherein the at least one circumferential groove comprises a retaining groove that receives and engages with the circumferential finger; and wherein axial movement of the second body relative to the first body is resisted by the engagement of the circumferential finger with the retaining groove.

Preferably, the second end of the fluid flow passage is axially spaced from the first body and/or the first end of the fluid flow passage is axially spaced from the second body.

Optionally, the first body has a threaded end portion for threadedly engaging with a threaded attachment; and wherein the threaded end portion defines the first end of the fluid flow passage. The threaded end portion may, for example, comprise a male threaded end portion or a female threaded end portion.

Optionally, the second body has a cylindrical end portion for engaging with a cylindrical attachment; and wherein the cylindrical end portion defines the second end of the fluid flow passage. The cylindrical end portion may, for example, comprise a spigot or a socket.

Preferably, the first body is formed from a first polymeric material, and the second body is formed from a second polymeric material; wherein the first polymeric material differs from the second polymeric material. The first polymeric material may, for example, comprise polyvinylidene fluoride, polyphenylene sulfide, polyvinyl chloride, chlorinated polyvinyl chloride, or polyphenylsulfone. Preferably, the first polymeric material contains reinforcing fibers. The reinforcing fibers may, for example, comprise glass fibers. The second polymeric material may, for example, comprise chlorinated polyvinyl chloride.

Preferably, the first body comprises a molded first body. The second body is preferably overmolded over at least a portion of the first body, including the first interface surface.

In preferred embodiments, the pipe fitting is a composite transition fitting for fluidly connecting, via the first portion and the second portion of the fluid flow passage, a first fluid conduit formed from a first material and a second fluid conduit formed from a second material which differs from the first material. Optionally, the first body connects to the first fluid conduit at the first end of the fluid flow passage, the first fluid conduit being formed from a metallic material; and wherein the second body connects to the second fluid conduit at the second end of the fluid flow passage, the second fluid conduit being formed from a polymeric material.

Preferably, the pipe fitting is lead-free and/or metal-free.

In some embodiments, the first body comprises an overlapping portion and a non-overlapping portion; wherein the second body is overmolded over the overlapping portion; wherein the second body is spaced from the non-overlapping portion; and wherein the first end of the fluid flow passage is defined by the non-overlapping portion. Optionally, the second body comprises an attachment portion and an extension portion; wherein the attachment portion is attached to the overlapping portion of the first body; wherein the extension portion is spaced from the first body; and wherein the second end of the fluid flow passage is defined by the extension portion.

In another aspect, the present invention resides in a method of producing a pipe fitting, the pipe fitting comprising: a first body and a second body that together at least partially define a fluid flow passage; the first body defining a first portion of the fluid flow passage that extends from a first end of the fluid flow passage to a first internal opening; the second body defining a second portion of the fluid flow passage that extends from a second internal opening to a second end of the fluid flow passage; wherein the first body has a first interface surface that radially surrounds the first internal opening, the first interface surface having a plurality of anti-rotation grooves; wherein the second body has a second interface surface that radially surrounds the second internal opening and engages with the first interface surface, the first internal opening being in fluid communication with the second internal opening, and the second interface surface having a plurality of anti-rotation fingers that are each received by and engage with a corresponding one of the anti-rotation grooves; and wherein rotation of the second body relative to the first body is resisted by the engagement of the anti-rotation fingers with the anti-rotation grooves; the method comprising: producing the first body; and overmolding the second body over at least a portion of the first body, including the first interface surface. Preferably, producing the first body comprises injection molding the first body.

Further aspects of the invention will become apparent upon reading the following detailed description and drawings, which illustrate the invention and preferred embodiments of the invention.

