PIPE FITTING

TECHNICAL FIELD OF THE INVENTION

This invention relates to a pipe fitting.

BACKGROUND ART

Various pipe fittings are commonly in use today but these have a variety of drawbacks which limits their usefulness. . For example, many fittings require the use of ferrules or cones to attach and/or seal the fittings to the pipes. These tend to distort preventing their removal. In the event that removal is required, the pipe must be cut which renders it unusable. A further disadvantage of ferrules or cones is that the compression created to grip and seal the pipe may cause the pipe to collapse if used on thin-walled pipes or if the pipe is used for hot water, the softening of the pipe causes it to decompress and the ferrule is loosened and separates from the pipe.

Once installed on a pipe, the location of a fitting cannot be adjusted if a ferrule has been used, and the ferrule must be cut off. In most cases, the pipe is damaged by the compression and must have the damaged piece removed.

Another disadvantage is that plastic fittings using ferrules or cones cannot be used for high pressure applications and they cannot generate sufficient compression to grip and seal. As a result of these disadvantages, currently available fittings are expensive and require tools to facilitate fitment.

In an attempt to address some of these issues, several persons have proposed the use of fittings having grip rings which bite into the pipe to inhibit removal.

EP 1020677 (Le Quere) describes a coupling having one end attached to a component and a tubular sleeve for receiving the end of a pipe with the sleeve. A seal

and a grip ring having deformable claims are located within the sleeve and secured in place by means of a threaded detachable ring which is tightened into the end of the sleeve to retain the grip and seal, using a special tool. The deformable claws of the grip ring prevent the pipe from being pulled from the coupling without loosening the detachable ring.

In GB 2182743, Beasley describes a coupling which has a sleeve-like body with at least one open end and an annular grip member having axially and radially extending teeth, the grip member being locatable against an internal shoulder of the sleeve. A rubber C-ring is located behind the grip member and means to locate and secure the C- ring within the sleeve, comprises an insert. The insert is removable. The teeth of the grip ring are angled and dimensioned to bite into the pipe when the coupling is fitted.

GB 234 9931 (Thomas et al) describes a push-fit attachment which comprises a hollow outer cover and a grip ring. In particular, the teeth of the grip ring are arranged in a frusto-conical array with the narrow edge of the frustum of cone facing generally along the direction of insertion of the pipe to be joined. Each tooth also has a shaped tip to reduce interference when inserting the pipe but enhancing bite when it is attempted to withdraw the pipe.

It is therefore clear that the use of a toothed grip ring in prior art pipe couplings is fairly well established. Typically, these are designed to be non-removable in principle, and accordingly, removal requires excessive force or special tooling and tends to result in damage to the pipe being coupled. In certain cases, if the join is compromised or problematic, the pipe may need to be cut to remove the coupling.

It is accordingly an object of this invention to provide a novel and relatively inexpensive pipe fitting that will overcome the above disadvantages or at least provide an alternative pipe fitting design which may be used on copper, polycop and aluminium lined pipes.

These fittings may be described as internal where the pipe end is received over the end of the body portion of a coupling, or may be external in which case the pipe end is received into the body of the pipe coupling.

DISCLOSURE OF THE INVENTION

According to the invention, a push fit pipe coupling comprises a body with an open- ended passageway extending therethrough, each open end providing a formation for receiving a pipe end , one or more O-rings locatable between the body and the received pipe, and a gripping member locatable about the body; and meana for securing the grip ring about the body, to define a pipe registry between the gripping member and the body; the gripping member including one or more sets of radially and inwardly extending teeth.

In one form of the invention, which is particularly relevant for the purposes of this application, the body receives the pipe end therein. In this form, the coupling of the invention is designed to be what is commonly referred to as an external coupling in which the body receives the pipe end internally (as opposed to the pipe end fitting over the end of the body). Typically, the body would comprise what is commonly known as a centre piece which is a body having an open-ended passageway extending therethrough. In this form, the body may further include one or more stopper elements against which the pipe end is held by the gripping member. The stopper member may comprise an internal radial flange at the midpoint of the body.

In one form, the gripping member includes a single set of teeth and the means for securing the gripping member is integral with the gripping member. In this form, the gripping member and the body include complimental interengaging formations which when interengaged, lock the gripping member and the received pipe securely but releasably together. An advantage of the coupling of this formation is that this coupling is releasably securable without requiring the use of a special tool or undue force which would render the gripping member disposable rather than re-usable. In this form of the invention, the inner

circumference of the opening of the body is tapered inwardly toward the centre of the passage at approximately the same angle as that of the teeth.

In this form of the invention, the gripping member may comprise a short generally tubular sleeve including a set of teeth circumferentially arranged about the inner diameter of one end thereof, the opposite end of the tubular section including one or more keyhole formations for engaging key formations integrally formed about the end of the body. The key formations preferably comprise outwardly directed radial ridges. The keyhole formations preferably comprise a longitudinal slot dimensioned to receive the key ridges, the longitudinal slot including a transverse slot at the end thereof into which the key ridges are slidable on rotation of the gripping member. In one form, four key ridges and keyhole slots are provided, enabling the gripping member to be slided onto the end of the body and rotated one quarter turn to lock the gripping member in place, once the pipe has been inserted. Removal of the gripping member may be undertaken, by reversing the locking process and then removing the pipe

In a further alternative form of the invention the sleeve includes feet formations for engaging the underside of the radial ridges when the sleeve is rotated to lock the gripping member in place.

In an alternative form of the invention, the key formations comprise chamfered ridges in which the longitudinal edges and one transverse end of the ridge are chamfered. The same transverse end of the each ridge is chamfered. In this form, the tubular section of the gripping member includes one or more narrow, longitudinal expansion slots, and the keyhole formations comprise transverse slots dimensioned to receive the chamfered ridges. The longitudinal slots extend from the end of the sleeve opposite to the teeth, toward the teeth, but without extending the entire length of the tubular section. In this form, the gripping member is pushed over the end of the body, the chamfers and the expansion slots enabling this to occur. No rotation is required and it can be pushed straight on due to the chamfer being tapered in the front and the key ridges settle firmly into the keyhole slots. Removal is by rotating the gripping member in the direction of the chamfered ridges on the body with any form of pliers. Rotation will force the expansion of the gripping

member due to the slots and causes the longitudinal slots holding the gripping member and body together to separate themselves thus releasing the pipe

In and alternative form of the invention, the gripping member comprises a double toothed gripping circlip, and again a keyhole and key arrangement is employed. In this form, the keyholes may comprise one or more transverse slots for engaging a corresponding number of key ridges about the end of the body. The key ridges may be chamfered as described above. In this form, the gripping member is urged over the end of the body with the circlip construction of the gripping member allowing the diameter thereof to expand during this process. Once in place a cover sleeve made of any material is then slid over the circlip holding it in its ready to use position. Removal is by removing the sleeve, allowing the circlip to expand and the pipe to be released. The circlip will remain on the body unless removed specifically. The cover sleeve may include a locking formation to prevent accidental removal.

In a further alternative form of the invention in which two sets of radially and inwardly directed teeth are provided, the body is provided with a radial groove or ridge usually created to accommodate the O-ring that creates the seal, and defining a surface of engagement for the first set of teeth, at a point remote from the open-end of the body. Typically, the body would comprise what is commonly known as a centre piece which is a body having an open-ended passageway extending therethrough and including at the midpoint thereof, a radial flange. In this form of the body described above, a radial groove is located proximal to the radial flange. In this form, the body may further include one or more stopper elements against which the pipe end is held by the gripping member. The stopper member may comprise an internal radial flange at the midpoint of the body.

In an alternative form, the radial ridge or groove is not provided, and the two sets of teeth of the gripping member are angled inwardly and axially toward each other.

In this form of the invention in which the groove is provided, the first or body- engaging set of teeth are dimensioned to be shorter than the second or pipe engaging set,

in order to accommodate the external diameter of the pipe which is slightly smaller than the external diameter of the body into which it slides.

In use, the double toothed gripping ring is located about the body with the first set of teeth engaging the radial grooves. The O-ring is positioned longitudinally between the gripping member and the open end of the body and is locatable within an internal radial groove in the internal wall of the body. The cover sleeve is slided over the double toothed gripping ring or circlip, with the radial flange of the cover sleeve defining an opening for insertion of a pipe end to be joined. The pipe end is pushed through the opening and slided through the O-ring and into body, until it abuts the internal radial flange. When it can be pushed no further, the coupling is complete. The pipe cannot be pulled from the coupling as the oppositely disposed teeth of the double toothed gripping ring or circlip are engaging the body and pipe in different directions.

However, should it be required to de-couple the pipe, the cover sleeve is slid off by hand, allowing the circlip to open and expand out of engagement with the body and the pipe. No tools are required for coupling or de-coupling.

In the event that it is required that the sleeve be removed accidentally or in an unauthorised manner, the sleeve may be provided with a locking mechanism requiring a tool for unlocking only.

The double-toothed gripping member preferably comprises sprung stainless steel of predetermined thickness, but may comprise a variety of materials, including a plastics material.

The cover sleeve may also comprise metal or plastic and may be provided with a series of locating apertures to be aligned with similar apertures in the circlip and providing a visual confirmation that the pipe has been correctly and fully inserted into the coupling.

According to a second aspect of the invention finding application in situations in which the pipe end is received internally or over the end of the body of the coupling, a

push fit pipe coupling comprises a body with an open-ended passageway extending therethrough, each open end providing a formation for receiving a pipe end snugly thereover, one or more O-rings locatable between the body and the received pipe, and a gripping member locatable about the body; and means for securing the grip ring about the body, to define a pipe registry between the gripping member and the body; the gripping member including two sets of radially and inwardly extending teeth, the first set of teeth engaging the body of the coupling and the second set engaging the pipe to be coupled.

In the preferred form of the invention, the gripping member comprises a circlip and means for urging the circlip towards a closed position. In the preferred form of the invention this is achieved by the provision of a cover sleeve slidable over the double- toothed circlip.

In an alternative form of the invention, the ends of the circlip may include interlocking formations which enable the circlip to be secured about the body of the coupling without the use of a sleeve. In one form this may comprise an L-shaped slot and a ridge formation slidable therein.

It is however, in the Applicant's opinion, better to provide a sleeve for this purpose. In the preferred form, the sleeve includes an inwardly directed radial flange or lip having an internal diameter slightly larger than the external diameter of the pipe to be coupled.

In the preferred form of the invention, the body is provided with a radial ridge or groove defining a surface of engagement for the first set of teeth, at a point remote from the open-end of the body. Typically, the body would comprise what is commonly known as a centre piece which is a body having an open-ended passageway extending therethrough and including at the midpoint thereof, a radial flange of the external surface thereof. In the preferred form of the body described above, the radial ridge is located proximal to the radial flange.

In an alternative form, the radial ridge or groove is not provided, and the two sets of teeth of the gripping member are angled inwardly and axially toward each other.

In the preferred form of the invention in which the radial ridge or groove is provided, the first or body-engaging set of teeth are dimensioned to be longer than the second or pipe engaging set, in order to accommodate the external diameter of the pipe which is slightly larger than the external diameter of the body onto which it slides.

Also in the preferred form, the radial ridge is provided in preference to a radial groove as this allows the internal bore of the body passageway to be of greater diameter for a better rate of flow through the coupling.

In use, the double toothed gripping circlip is located about the body in abutment with the radial flange with the O-ring being positioned between the gripping member and the open end of the body. The cover sleeve is slided over the circlip, with the radial flange defining an opening for insertion of a pipe end to be joined. The pipe end is pushed through the opening and slided over the O-ring and body, to be interposed between the circlip and the body. When it can be pushed no further, the coupling is complete. The pipe cannot be pulled from the coupling as the oppositely disposed teeth of the circlip are engaging the body and pipe in different directions.

However, should it be required to de-couple the pipe, the cover sleeve is turned or slided off by hand, allowing the circlip to open and expand out of engagement with the body and the pipe. No tools are required for coupling or de-coupling.

In the event that it is required that the sleeve be removed accidentally or in an unauthorised manner, the sleeve may be provided with a locking mechanism requiring a tool for unlocking only.

The double-toothed circlip preferably comprises sprung stainless steel of predetermined thickness, but may comprise a variety of materials, including a plastics material.

The sleeve may also comprise metal or plastic and may be provided with a series of locating apertures to be aligned with similar apertures in the circlip and providing a visual confirmation that the pipe has been correctly and fully inserted into the coupling.

The body may also comprise what is known as a multi-stage coupler which is designed to engage pipes of different diameters. In this form, the grip ring must simply be designed to be of sufficient length to extend beyond the second or narrow stage of the multi-stage coupler to enable the second set of teeth of the grip ring to engage a pipe of narrower internal diameter. The teeth are thus able to accommodate a range of differing external diameters of pipes.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described below with reference to the accompanying drawings in which:

Figures 1 to 4 show a pipe coupling according to the invention, in which the gripping member includes a single set of teeth and an integral securing means, and in which:

Figure 1a is a perspective view of the one form of the invention;

Figure 1 b is a side view of figure 1 a and

Figure 1 c is a sectional view through figure 1 b;

Figures 2 a, b and c are similar views of an alternative form of a pipe coupling;

Figure 3 is a perspective view of a further alternative form of the invention;

Figures 4a, b and c are similar views to figures 1 a to c of the preferred form of the invention;

Figure 5 is a sectional view through a pipe coupling according to the invention in which the securing means is not integral and the gripping means comprises a double-toothed grip ring;

Figure 6 is a sectional view through an alternative embodiment of a pipe fitting in accordance with the invention; and

Figure 7 is a cross-section view of a pipe fitting of Figure 6;

BEST MODE FOR CARRYING OUT THE INVENTION

In the drawings the body 10 of a pipe coupling according to the invention, is designed to receive a pipe12 internally so that the coupling of the invention engages the external surface of the pipe. Internal circumferential grooves 14 are provided to house sealing o-rings 16 which provide a water-tight seal between the body of the coupling and the pipe. A stopper in the form of an internal radial flange 18 is provided at the midpoint of the passageway in the body and it is against this stopper, that the pipe 12 is held by the gripping member which is generally referenced 20.

In figures 1 , and 4, the body further includes four key formations in the form of outwardly directed radial ridges 24 located at the opening of the body. In figure 2 the key formations comprises chamfered ridges 26 located slightly away from the opening of the body. The internal circumference of the opening of the passageway is tapered 28 as shown, at approximately the same angle as that of the teeth 34 of the grip ring 30.

In figures 1a-c, the gripping means comprises a single grip ring 30 located at the end of a short sleeve 32. The teeth 34 of the grip ring are angled radially inwardly, in the direction in which the pipe is to be inserted. Integral securing means is provided in the form of four keyhole slots 36 which slidably engage the key ridges 24 located about the opening of the body 10. The wide section 38 of the slots is dimensioned to receive the key ridges 24 and once engaged, a quarter rotation of the sleeve moves the ridge into the narrow transverse slot 40, maintaining the gripping means firmly engaged to the body. An additional securing means in the form of a cover sleeve may be employed (as shown in figures 4 and 5, but this is not necessary.

In figures 2a-c, the gripping means again comprises a single grip ring 30 at the end of a short sleeve 32 and the teeth 34 are angled in the same way as in figure 1. In this form however, the key formations on the body 10 comprise chamfered ridges 26 as described above. The ridges are chamfered on three sides, both longitudinal sides 26a and one transverse end 26b being angled to facilitate sliding the grip ring sleeve 32 over the ridges. To further assist in this process the grip ring sleeve 32 includes one or more

longitudinal expansion slots 42. The chamfer at one end 26b only allows the grip ring to be rotated in one direction only to slide the ridges into keyhole slots 44 and lock the grip ring in place without requiring a cover sleeve.

Turning now to figure 3, an alternative form of grip ring 30 is shown. It may be used with a body having the outwardly directed radial ridges 24 shown in figure 2. The grip ring is slided into place between the ridges 24 and rotated by a quarter turn for the feet 46 to engage the undersides of the ridges 24, locking the grip ring in place.

In figure 4, the grip ring has a similar construction to that shown in figure 2 except that the grip ring comprises a circlip, being split at 48 to enable the ring to slidingly engage the body of the coupling and for the chamfered ridges 26 to engage the keyhole slots 44. A cover sleeve 50 may be provided as additional securing means.

In figure 5, an alternative push-fit external pipe coupling 60 is shown to comprise a body 62, double grip circlip 64 and a cover sleeve 66.

The body 62 comprises an open-ended passageway 68 and includes a flange 70 at is midpoint and a groove 72 adjacent the flange. The body includes an internal flange 74 which acts as a stopper for the pipe end 76 which is to be inserted into the coupling. An internal radial groove 78 is provided toward the open end of the body, with a sealing ring 80 (for example an O-ring or banded ring) located therein.

On the right hand side "A" of the flange 70, the pipe 76 has not yet been fitted and the coupling is not fully assembled while on the left hand side "B", the pipe has been pushed into the assembled coupling.

The double-grip circlip 64 comprises stainless steel and includes two sets of radially and axially directed teeth 82, 84. The first set of teeth 82 engage the body of the coupling and specifically the groove 72, while the second set of teeth 84 engage the pipe 76 (as shown at 86). The first set of teeth 82 are typically shorter than those of the

second set 84 to cater for the difference in external diameter of the body 64 and the pipe 76 which is slided into the body.

In use, the coupling is assembled by locating the gripping circlip 64 with teeth 82 in the groove 72. Cover sleeve 66 is located over the circlip. The cover sleeve includes a circumferential lip 86 defining an internal diameter slightly larger than that of the pipe to be fitted.

Once the coupling is assembled, a pipe is push-fitted into the body 62 until the end of the pipe abuts the flange 74. This interposes the pipe between the grip circlip 64 and the body 62. Any attempt to remove the pipe results in teeth 84 engaging the pipe to , oppose the pulling force, while teeth 82 engage the groove 72 of the body to also oppose the pulling force and any resultant pressure on teeth 84. This arrangement has been successfully tested as high pressures with copper, polycop and aluminium-lined pipes.

In figure 6, a push-fit pipe coupling 90 is shown to comprise a body 92, double grip circlip 94 and a cover sleeve 96.

The body 92 comprises an open-ended passageway 98 includes a flange 100 at is midpoint and a ridge 102 a short distance therefrom, with a sealing ring 104 (for example an O-ring or banded ring) located in a groove toward the open end thereof.

On the right hand side "A" of the flange 100, the pipe 106 has not yet been fitted and the coupling is not fully assembled while on the left hand side "B", the pipe has been pushed into the assembled coupling.

The double-grip circlip 94 comprises stainless steel and includes two sets of radially and axially directed teeth 108, 110. The first set of teeth 108 engage the body of the coupling and specifically the ridge 102, while the second set of teeth 110 engage the pipe 106 (as shown at 112). The first set of teeth 108 are typically longer than those of the second set 110 to cater for the difference in external diameter of the body 94 and the pipe 106 which is slided onto the body.

In use, the coupling is assembled by locating the gripping circlip 94 with teeth 108 in the groove defined by the flange 100 and the ridge 102. Cover sleeve 96 is located over the circlip. The cover sleeve includes a circumferential lip 104 defining an internal diameter slightly larger than that of the pipe to be fitted.

Once the coupling is assembled, a pipe is push-fitted over the body 92 until the end of the pipe abuts the ridge 102. This interposes the pipe between the grip circlip 94 and the body 92. Any attempt to remove the pipe results in teeth 110 engaging the pipe to oppose the pulling force, while teeth 108 engage the ridge 102 of the body to also oppose the pulling force and any resultant pressure on teeth 110., This arrangement has been successfully tested as high pressures with copper, polycop and aluminium-lined pipes.

In figure 7, a slightly different version of the coupling is shown which enables fitting of pipes of two different diameters. In this form, the body 92 comprises what is known as a multi-stage coupler and includes portions 116 and 118 having different external diameters. Different - sized sealing rings 104 and 120 are also provided.

The principle of operation is identical to the version shown in figure 6.