The present invention relates to a connector.

In particular, it relates to a connector with a screw thread which will engage with a second part having a complimentary screw thread to hold the two together.

Such connectors may, for example, be a nut and bolt connection or a tubular connection with a male screw thread for engagement with a complementary component with a female screw thread for example in pipe work used in plumbing.

With any such screw threaded connection of this type, the intention is commonly to screw the two components together, usually with the application of a tool such as a wrench or spanner, in order to engage the components as tightly as possible so that the friction between the engaging threads is sufficient to prevent relative rotation of the components in a sense which will tend to undo the threaded connection.

We are developing a connector with a screw threaded connection which is specifically designed to be tightened only be hand (i.e. without the application of a tool such as a wrench). Such a connection cannot be made as tightly as a connection which requires the use of a tool and therefore there is a possibility of the connection working loose over time.

The present invention addresses this problem.

According to the present invention that was provided a connector according to claim 1.

By providing at least one deformable interference element which causes an increase in the local profile of the screw thread, and which interferes with the other thread, the present invention provides enhanced frictional grip between the two screw threads. Further, this is a frictional fit mechanism which does not rely entirely on the conventional engagement between the screw threads in which the flanks of adjacent threads are held against one another when the threaded connection has been tightened by a tool. The projecting annular shoulder and stop arrangement limit the extent to which the two components can approach one another in the axial direction thereby avoiding placing undue stress on the threads. The interference element allows the required frictional fit to be achieved even through the threads are not as tightly engaged as the might otherwise be.

The present invention bears some superficial similarity to our own earlier EP0448361. This discloses a screw threaded joint in which a deformable material is provided between the threads. However, this material is provided to create a seal between the threads and has nothing to do with a threaded joint in which the degree of axial movement between the components is limited by a stop.

The reference to axial direction refers to the orientation in the vicinity of the coupling. The connector body can have a non-axial shape behind the coupling. For example, it can have an elbow or T shape.

Preferably the connector further comprises a resilient annular seal positioned axially between the male thread and the first shoulder, and around the first connector body, wherein the stop limits the maximum compression of the resilient annular seal in the axial direction. As well as the overtightening protection above, the addition of a seal provides a seal between the interface of the two shoulders. As compared with EP0448361 , this decouples the sealing function from the connection function which is carried out by the screw threads and interference element. As such, the seal can be made more effective as it is away from any variations in geometry caused by the screw threads and forms an annular which is compressed to a controlled extent in a axial direction.

Under these circumstances, the at least one deformable interference element is preferably integral with the resilient annular seal. Thus, the at least one deformable interference element is put in place simply by the act of placing the annular seal around the first connector body. This facilitates the manufacturing process and also provides resistance against dislodging the annular seal with the connection is made up. The annular seal may also be provided with external lugs which align the annular seal with respect to the first connector body. These lugs will only align once the seal is seated. With the addition of the at least one deformable interference element to the seal, this can align the seal with respect to the first connector body as soon as the seal is placed on the first connector body thereby making it more straight forward to align at an earlier stage. There may be a single deformable interference element which is positioned between adjacent threads of the male or female thread. However, preferably, there are a plurality of deformable interference elements arranged across a plurality of adjacent turns of the thread. The deformable interference elements may be circumferentially staggered with respect to one another. However, preferably, the plurality of deformable interference elements are circumferentially aligned. This facilitates the manufacturing process.

The at least one deformable interference element may be moulded feature moulded when the first or second connector body is moulded. In this case, it may be moulded of the same material as the majority of the first or second connector body. Alternatively, it may be made of a different material in a co-moulding process.

As a further possibility, the at least one deformable interference element may be formed as a separate component which is fitted to the first or second connector body.

For example, if the connector further comprises a seal or a washer, the at least one deformable interference element may be formed as part of the seal or washer and assembled onto the first or second connector body.

If the deformable interference element is a separate component, it may be fitted over the crests of the thread. Alternatively, the thread may be provided with a groove to receive the at least one deformable interference element.

The connector may be any suitable material. However, as mentioned above, the connector is particularly intended to be made up with only hand pressure. As such, it is particularly applicable to a material which might be damaged by overtightening, such as cast metal. However, most preferably at least one of the first and second connector bodies is preferably formed of a plastics material.

This grooved arrangement in a connector made of plastics material forms a second aspect of the present invention which provides a connector according to claim 12. This provides a simple way of providing an interference element which is particularly suited to a plastics connector. Further, at least one of the first and second connector bodies is devoid of opposing flat surfaces on its outer wall. This is particularly applicable for the component that is intended to be screwed onto the other components as this makes it difficult for a user to gain purchase by applying a tool.

This forms a third aspect of the present invention which is a connector according to claim 13. Such a connector combines the deformable interference element and a connector body which is devoid of opposing flat surfaces. The lack of opposing flat surfaces limits the extent to which the two components can be tightened on to one another, while the deformable interference element compensates for lack of tightness by providing an enhanced interference fit. In EP0448361 , only the screw threads are illustrated such that there is no information derivable on the geometry of the first and second connector bodies. However, given that this reference is attempting to provide an enhanced seal between the screw threads, there is no reason for the components to be devoid of opposing flat surfaces as the formation of a hand tight joint is not a consideration in this reference.

Examples of connectors in accordance with the present invention will now be described with reference to the accompanying drawings in which:

Fig. 1 A is a perspective view of the first connector body and seal with deformable interference elements in a disassembled configuration;

Fig. 1 B is a view similar to Fig. 1 A in a partially assembled configuration which also depicts the second connector body;

Fig. 1 C is a view similar to Fig. 1 A with the seal in place on the first connector body;

Figs. 2A to 2C are views similar to Figs. 1A to 1 C showing a second connector (although Fig. 2B does not show the second connector body);

Fig. 3 is a perspective view of a third connector body;

Fig. 3A shows a detail of the thread of Fig. 3;

Fig. 4 is a perspective view of a fourth connector body; Fig.4A shows a detail of the thread of Fig. 4;

Fig. 5 is a perspective view of a fifth connector body;

Fig. 5A shows a detail of the thread of Fig. 5;

Fig. 6 is a perspective view of a sixth connector body; and Fig. 6A shows a detail of the thread of Fig. 6.

The connector comprises a first connector body 1 and a second connector body 2. The second connector body 2 is a cap which has a female screwed thread 3, the second connector body 2 is common to all of the subsequently described examples and will therefore not be described separately in relation to each example. It should be noted that the modifications described below in relation to the thread of first connector body can instead be made on the second connector body.

Returning to the first connector body 1 as shown in Fig 1 A, this has a tubular threaded portion 4 with a male screw thread 5 that is complimentary to the female screw thread 3.

The connector body has a main body portion 6 which has a conventional construction. A central bore 7 extends fully through the first connector body 1. An outwardly projecting annular shoulder 8 is positioned between the tubular threaded portion 4 and the main body portion 6. The annular shoulder 8 is provided with an annular recess 9 for receiving an elastomeric seal 10 provided with a pair of radially projecting lugs 1 1 which fit into complementary recesses 12 in the annular recess 9 to locate the seal 10 with respect to the first connector body 1.

The seal 10 is provided with a pair of resiliently deflectable rods 13 which are initially in the same plane as the seal as shown in Fig. 1 A. The male screw thread 5 is provided with a pair of diametrically opposed axial slots 14 (only one of which is visible in the drawings, but the other has the same configuration and is spaced 180° from, the slot depicted in the drawings). In order to assemble the seal 10 onto the first connector body 1 , the seal 10 is presented to the first connector body in the position shown in Fig. 1A in which the rods 13 are aligned with the slots 4. Pushing of the seal 10 onto the first connector body 1 causes the rods 13 to deflect outwardly as shown in Fig. 1 B such that they align with the slots 14 allowing the seal to be slid, while maintaining the same orientation, to the fully engaged position shown in Fig. 1 C in which the rods 13 now lie in the corresponding slots 14. As will be appreciated from Fig. 1 C, the rods 13 project radially outwardly beyond parts of the adjacent thread.

The rods 13 project well above the roots of the thread and may even project to a radial extent beyond the crests of the threads.

When the second connector body 2 is screwed onto the first connector body 1 by engaging the female 3 and male 5 screw threads, the rods 13 will be in the path being followed by the crests of the female screw thread 3 and will be compressed by the crests of the female screw thread 3. The second connector body 2 is fully engaged with the first connector body 1 when the end of the first connector body 2 meets the annular shoulder 8 thereby preventing over tightening of the two components. In this position, the rods 13 will provide a small resilient force between the first 1 and second 2 connector bodies at multiple location on either side of the connector. These engagements increase the frictional resistance between the two components in addition to the conventional friction force between the flanks of adjacent threads. The additional engagement with rods 13, however, provides enhanced protection against accidental undoing of the threaded connection, particularly when the connection has only been made with hand tight pressure. This has been found sufficient to prevent accidental uncoupling of the threaded connection as a result of the forces encountered in use which might otherwise dislodge the connection such as vibrations and cyclic thermal loads.

The second connector body 2 can bear against the seal 10 before being fully located against the annular shoulder 8. Any further rotation of the second connector body 2 in this situation causes a rotary force to be applied to the face of the seal 10. However, the engagement between the lugs 1 1 and recesses 12 as well as the engagement between the rods 13 and slots 14 will resist this rotational movement of the seal 10 thereby preventing the seal from being dislodged.

A second example is shown in Fig. 2. This uses the same first connector body 1 and second connector body 2 as in the first example, although the recesses 12 are absent. The rods 13A are separate from the seal 10A. Once this seal is in place as shown in Fig. 3B, the seal rods 13A are placed in the slots 14 and are held in place by a combination of a friction fit in the slot 14 and by being held at one end by the seal 10A. The attachment of the second connector body 2 is the same as the disclosed in relation to the first example above.

Fig. 3 showed a third example of a connector body. In this case, instead of having the rods 13 and slots 14, the first connector body 1 is moulded with axially extending wall 30 which extends for substantially the full length of the tubular threaded portion 4. As shown in Fig. 3A, the depth of this wall 30 is the same as the depth of the grooves such that the top of the wall 30 is level with the crests 31 of the screw thread.

It should be noted that the wall 30 does not need to extend for the full axial length of the tubular threaded portion 4. Further, there is no reason the wall 30 needs to extend axially as shown in Fig. 3. Instead it could be circumferentially staggered from one turn of the thread to the next. In the Fig. 3 example there is a second wall diametrically opposed to the first wall. Flowever, there could be just one wall, or more than two walls.

When the second connector body 2 is threaded onto the first connector body the crests of the female screw threads 3 of the second connector body 2 will cut into the wall 30 thereby deforming it. In the fully assembled position, this provides enhanced frictional engagement with the female screw threads 3 and the wall 30. The wall 30 may be of a resilient material in which case it deforms resiliently when the threads are assembled. Alternatively, it may be moulded of the same material as is used for the first connector body 12 in which case it may be plastically deformable.

The fourth example shown in Figs. 4 and 4A are similar to the third example except that the wall 40 now finishes short of the crests 41 of the male threads 5. Otherwise, this operates in the same way. It is also possible that the wall is made to extend for a short distance above the crests of the male screw thread.

The fifth example shown in Figs. 5 and 5A is similar to the fourth example. The only difference is that the feature 50 within the tubular threaded portion 4 is a different shape. The features 50 extends to a greater circumferential extent than the walls 30, 40 such that these spread the fictional load between the screw threads over a longer circumferential portion.

The sixth example of Figs. 6 and 6A shows the feature in the form of a ridge 60 which runs up to the crests 61 of the male screw. The ridge 60 may be a resilient component which is co-moulded with the main part of the first connector body 1 or may be made of the same material as the main connector body 2. As will be appreciated from Fig. 6A, the shape of the ridge 60 means that it will engage with a greater portion of the depth of the flanks of the female screw thread 3 and requires less deformation of the material of the ridge 60.