CORRUGATED PIPE CONNECTOR

Abstract: A connector for corrugated pipes or rods comprises a housing (2) having an open end (3) for insertion of a pipe or rod into a bore (5). A pair of resilient locking members or fingers (9) are formed in the housing wall and include projec­ tions (10) which extend into the bore (5). The projections are so shaped as to lock into a single valley of the pipe or rod cor­ rugations to prevent withdrawal of the pipe or rod. Also disclosed are methods of moulding the connector in which the fingers (9) are held and/or forced outwardly from the mould during withdrawal of a central core which forms the bore (5) to avoid damage of the fingers by the core.

Description: The present invention relates to a connector for corrugated piping or conduit or piping having a ridge located adjacent its end (US-A-4575133 or EP-A-46616). With other existing corrugated flexible conduit for drainage or electrical work, available methods of joining involve encasing the joint and gluing to ensure an adequate join. This type of joint must be left, so that the glue or adhesive sets, to ensure a successful join. This takes the tradesman additional time, and the chemistry of the glue weakens the conduit and the connector cannot be reused. The present invention furnishes a push-on connector which provides a connection without the aid of adhesives, which is reusable and adjustable during installation, and in which operation of a locking means is enhanced. In broad form the invention provides a one-piece plastics connector, for affixing to a conduit having a ridge located adjacent to its end, comprising: a body open at one end to receive a conduit in a bore communicating with said open end; locking means located in said body so as to project into the said bore so as to lock onto the ridge of said conduit in said bore, so as to hold in said bare said conduit wherein said locking means comprises an axially extending resilient finger, having a projection, located at its free end being remote from the open end and which projects into the bore; and a line of weakness formed as a recess moulded in said finger or in the body of the connector, said recess enhancing the operation of said locking means. A sealing means can be provided to form a fluid tight seal between the connector and the conduit. This can be in the form of a resiliently deformable seal which is located in the bore to seal against (or adjacent the end,) of the conduit pushed into the bore, or at the open end of the bore where the recess is seated from said bore by flexible membranes joining the finger to the recess walls. However, preferably, the sealing means is a tapered section of said bore which cooperates so as to both axially and radially compress the flexible conduit pushed into said bore. The connector of the present invention can be utilized with any form of fittings, such as elbows, junctions, Y and T pieces, terminators, junction boxes, or fittings joining corrugated piping to rigid piping or corrugated piping to corrugated piping. The present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 illustrates a perspective view of a connector according to an embodiment of the present invention; Figure 2 illustrates a schematic sectional view of the connector illustrated in Figure 1 with a corrugated conduit connected therein - for clarity sake, a gap is shown between the conduit and the tapered portion 6 and the shoulder 7 of the bore; Figures 3a, 3b and 3c are part sectional schematic views illustrating steps in one method of moulding of the locking means of the embodiment shown in Figure 1; Figure 4 illustrates a schematic section view of another embodiment of a connector showing a corrugated conduit connected therein; One embodiment of the present invention is illustrated in Figures 1 to 3 of the accompanying drawings. The connector 1 comprises a housing 2 having an open end 3 for insertion of the corrugated piping or piping having a single ridge to effect connection thereto. The other end 4 is shown for threaded connection to a junction box or the like. However, this end could be designed for any type of connection or fitting. The bore 5 (Figure 2) is chosen so as to be slightly oversize to the outer diameter of the corrugated or threaded tubing or rod. The bore 5 as shown in Figure 2 has a tapered section 6 located, remote from the end 3 and terminating in an annular shoulder 7, with a smaller diameter bore 8, in communication therewith. The diameter of the bore 8 and the internal diameter of the conduit being substantially similar. The shoulder could be of any desirable width. Located intermediate the ends of the bore, in the substantially constant diameter section, are two resilient locking members or fingers 9 formed in the walls of said bore 5, and having projections 10 which extend into the bore 5. Thus, in clamping the connector 1 to a corrugated flexible piping as shown in Figure 2, the piping is pushed into the bore 5; the projection 10 being so shaped that the corrugations bear on the ramp 11 and force the projection 10 back out of the bore as shown in ghosting. The piping is then pushed into the tapered section 6 where it may abut against the annular shoulder 7. As the piping is forced further into the tapered section 6, the piping may be radially compressed by the increasingly narrowing diameter of the tapered section, to form a fluid tight seal therewith, and is also axially compressed. Both the projections 10 lock into a single valley of the corrugations of the piping, such that the face 12 of the projection abuts up against a ridge of the corrugations, to prevent the piping from being withdrawn from the bore 5; the ridges, in this example, being in a fluid tight seal against the walls of the tapered section. In another preferred form of the invention the tapered section of the bore could be replaced by a resilient seal which abuts against the end of the conduit or against its walls to form a fluid tight seal or the resilient seal could be utlized as well as the tapered section described before. To assist in the working of the locking members or fingers 9, the fingers 9 have a line of weakness 28, located internally as shown in figure 4, or externally (not shown), or a recess 13 as shown in Figures 1 and 2 which produces a thin walled section joining the locking members to the connector. This greatly increases the flexibility of the locking member, and produces a hinge at the end of or along the resilient member opposite the engagement tooth to increase the forcing of the tooth into engagement with the corrugations when a withdrawal force is exerted on said conduit held in said connector. The line of weakness could be of any desirable shape or size such as an arc or a straight line. Additionally with the recess 13 as shown in figure 1 and 2 the centre of rotation of this hinge is moved further outwardly from the tooth or projection point, where the tooth engages the ridge in the conduit, thus increasing the length of the moment arm and enhancing the 'over centre' action, such that, if the conduit has been longitudinal compressed on insertion or it is attempted to be removed, the force of the corrugations on the face 12 produces a bending moment on the locking member, or finger, drawing the projection 10 deeper into engagement with the ridge of the conduit, to resist withdrawal of the conduit from the connector. Preferably as shown in Figure 2 the leading face 12 of the projection 10 is angled inwardly away from the open end of the connector to prevent the projection 10 "riding" up the ridge of the corrugations, if a withdrawal force is applied to the conduit. This relief or inclination is equal to or greater than the maximum angle of inward bending of the finger. With the above described locking means, the corrugated piping may be released by means of a suitable tool inserted in the opening 14 or inserted along the recess 13 to engage on the ramp 23, to force the projections out of the bore 5. The position of the projection 10 in said bore and its relationship with the tapered surface or resident seal or abutment is so chosen that it traps preferably between two to five compressed corrugations. This compression provides a back force to drag the projection 10 into engagement. Further this also allows for accommodation of a variety of styles or profiles or pitches of corrugations. Also, the use of two opposed fingers having their respective projections, which fall into the same valley of corrugations, together with axial compression and where a tapered 6 is utilized, radial compression, allows for accommodation of varied pitches of corrugations, and dimensional tolerance of component parts. The present invention may be made from any suitable materials such as PVC or nylon, polypropolene, ABS, and can be used with pipes of varying sizes or types, for example, flexible plastic corrugated electrical conduit. The connector, as described above, can be utilised to form any desired connector, and could have any desired number of locking means as required. The connector of the present invention could be moulded to a wall or a portion of a junction box, which wall or portion is releasably held in fluid tight relationship with the junction box, i.e. a groove and mating projection, or be able to be connected to a recess in a junction box by any suitable means, such as tapered swaged fit. Because the connector is a unitary plastics moulding, a special method of moulding was developed to allow for the formation of the locking members 9. This method will now be described by way of example with reference to Figures 3a, 3b and 3c, which shows a part sectional view of one embodiment of the connector in the area of the locking member during moulding. The external mould 15 comprises a separately movable side mould 16 or an integral projection 16 which forms the U-shaped cut-out or recess 17, as shown in Figure 1. This projection mates with a recess in the internal mandrel or core 19, as shown in Figure 3a, to form the locking member or finger 9. In profile as shown in Figure 3a, the projection 10 extends into the bore 5 beyond the wall thickness 21, with the ramp 11 tapering back beyond the wall thickness, and rising again to the apex 22 at the level of the wail thickness 21, where it forms a ramp 25 which slopes to the recess 13 (not shown). When the material of the thus moulded connector has sufficiently solidified, the external mould 15 and its projection 16 (which can be integral therewith or move independentally) are withdrawn as shown in Figure 3b. The finger 9 has an undercut 26 as shown in Figure 1 which is engaged by the core pin 19 to retain the finger 9 in position. As the core pin 19 is withdrawn in the direction of arrow A as shown in Figure 3b, the ridge 23 as it bears on the ramp 24 forces the locking member outwardly from the bore 5, such that when the ridge 23 of the core pin 19 bears on the apex 22, the projection 10 is well clear of the core pin 19. Engagement of the ridge 23 with the slope 25 of the locking member as shown in Figure 3c prevents the projection 10 from interfering with the core pin 19 as it is removed from the bore 5. This thereby ensures that the leading edge 27 of the projection 10 is not damaged by the core pin 19. The recess 13 (shown in Figure 1) allows the retraction of the ridge 23 of the core pin 19 without distortion of the bore diameter. The locking member or finger 9 can then return to its original "as moulded" position by "plastics memory" or can be forced mechanically back to this position. In fact the finger 9 can be shaped so as to be angled into the bore. Rather than use the undercut 26 as shown in Figure 1, the undercut could be a recess located on the ramp surface 11 of the projection 10. To facilitate production of the dies the meeting surface 27 between the die projection 16 and the central cover 19 is formed as a plane in a chord of the diameter of the central core 19. It shall be obvious to people skilled in the art that the present invention could be used with corrugated conduit of any profile or could be used with non-corrugated pipes or rods having a ridge or a thread running around the pipe at a suitable distance from the end. The connector has applications for connection of electrical insulation piping, pool filtration and vacuum connections, vacuum cleaners, irrigation corrugated piping and lawn mower cable protection, drainage and waste water systems, plumbing and fluid reticulation systems, or optical fibre connection systems.

Claims: A one-piece plastics connector (1), for affixing to a conduit having a ridge located adjacent to its end, comprising: a body (2) open at one end (3) to receive a conduit in a bore (5) communicating with said open end; and locking means located in said body (2) so as to project into the said bore (5) so as to lock onto the ridge of said conduit in said bore (5), so as to hold in said bore (5) said conduit wherein said locking means comprises an axially extending resilient finger (9), having a projection (10), located at its free end being remote from the open end (3) and which projects into the bore (5); characterised in that a line of weakness (13, 28) formed as a recess is moulded in said finger (9) or in the body of the connector (2), said recess enhancing the operation of said locking means. A connector according to claim 1 characterised in that said recess is an axially extending recess (13) located in said bore (5), extending from the base of said finger (9) to the open end (3). A connector according to claim 2 characterised in that said recess (13) has a width substantially equal to that of the finger (9). A connector according to claim 1 characterised in that there is a laterally extending recess (28) on the outer surface of said finger (9). A connector according to any one of claims 1 to 4 characterised in that there is provided sealing means, in said bore (5), remote from said open end (3), which are adapted to seal against, in a liquid tight manner, the conduit pushed into the said bore (5). A connector according to claim 5 characterised in that said sealing means comprises a tapered section (6) of said bore (5) remote from said open end (3) whereby said conduit which is pushed into said bore (5) is compressed against and seals against the tapered section (6) in a liquid tight manner. A connector according to claim 5 characterised in that said sealing means is a resiliently deformable seal adapted to abut against the end of the conduit in a liquid tight manner. A connector according to any one of the preceding claims characterised in that the finger (9) has on its underside a ramp (25) rising adjacent the projection (10) from the finger (9) to an apex (22), intermediate the ends of the finger. A connector according to claim 8 characterised in that the apex (22) extends into the bore (5) a lesser distance than the projection (10). A connector according to any one of the preceding claims characterised in that said projection (10) has a substantially planar face (12), extending substantially radially to the bore (5) and facing away from the open end (3) of the body (2). A connector according to claim 10 characterised in that said substantially planar face (12) extends at an angle inwardly away from the open end (3) of the body (2).

Inventors: MCNEILL, SANDY, PETTY, JOHN
Applicants: ELCONNEX PTY. LIMITED
Application year: 1988
Main classification: F16L37
IPC codes: B29L23, G02B6, B29C65, F16L33, F16L37, B29C45, B29C33, B29C37