Improvements in or relating to tube couplings

Abstract: The disclosure relates to a tube coupling comprising a coupling body (10) having a throughway (11) open at one end (12) to receive an end portion of a tube (13) and having an internal cam surface (29) tapering towards the open end in which a collet (25) is located for locking the tube in the coupling body by engagement with the tapered cam surface, and having stop means (19) to limit entry of the collet into the throughway. The coupling body having a main body (10a) the throughway of which receives the end of a tube and contains said stop means to limit insertion of the collet and an end cap (10b) in screwthreaded engagement with the main body containing said open end (12) to the throughway and the tapered cam surface (24), Indexing means (24,30,31,33) between the end cap and main body to define different positions of rotational adjustment in the first of which a tube can be inserted and, by depressing the collet into the coupling body, released from the coupling body and in the second of which the collet is engaged with the stop means to prevent the collet being depressed into the coupling body to release the tube.

Description: This invention relates to tube couplings. Our "Speedfit" tube connector (UK Patent No. 1520742 and others) has a coupling body with a throughway open at one end and a tapered cam surface in the open end to receive a collet for locking a tube in the coupling. the collet is compressed against the tube by a slight withdraw of the tube and collet from the coupling body which locks the tube in the coupling body. the collet can be depressed into the body to release the tube. Our "Superseal" tube coupling design (UK Patent No. 2167147) has a separate sleeve screwed into the open end of the coupling body in which the tapered cam is formed. By screwing the sleeve into the coupling body the gripping action of the collet on the tube is increased. Also the collet becomes locked up in the coupling body and cannot be depressed to release the tube. The extent to which the sleeve is screwed into the coupling body can be determined visually but this can only be regarded as an approximate indication of the state of the coupling. DE-A-19625687 discloses a plug-in coupling for pipes comprising a sleeve body and a retaining means for connecting a pipe end to the sleeve body. The plug-in coupling is intended to make possible operationally correct handling at low cost during installation and obviates as far as possible the danger of installation errors. An entrainment member is arranged in the sleeve body which is axially displaceable. Upon reaching a predetermined insertion depth of the pipe end the entrainment member abuts against a counter-surface whereupon an acoustic signal and/or an oscillation signal is generated. EP-A-0694724 discloses a coupling for a plastic tube comprising a body having a seal, a compression bush for the seal, a ring for clamping the tube in the body and a nut for screwing on to the body which acts on both the seal compression bush and the clamping ring. The bush includes a ridge releasably engaged in a recess formed in the clamping ring to hold the ring in an enlarged state to allow the tube to be inserted through the ring and the seal without forcing it until the tube engages an axial shoulder in the body. The nut is then screwed fully on to the body causing the bush to compress the seal against the tube and at the same time tightening the clamping ring against the tube to hold the tube in the coupling body. An object of the present invention is to provide a tube coupling which can readily be adjusted manually between one state in which a tube can be locked in and released from the coupling body and a second state in which a tube is locked first and cannot be released. This invention provides a tube coupling comprising a coupling body having a throughway open at one end to receive an end portion of a tube, an internal cam surface tapering towards the open end in which a collet is located for locking the tube in the coupling body by engagement with the tapered cam surface, and stop means to limit entry of the collet into the throughway, the coupling body consisting of a main body the throughway of which receives the end of a tube and contains said stop means to limit insertion of the collet and an end cap in screwthreaded engagement with the main body containing said open end to the throughway and the tapered cam surface; wherein indexing means are provided between the end cap and main body to define different positions to which the cap can be screwed onto the body in a first of which a tube can be inserted into the throughway to be held by the collet and, by depressing the collet into the coupling body, released and from which the cap cannot be unscrewed and in a second of which, reached by screwing the cap further onto the body the collet is engaged with the stop means to prevent the collet being depressed into the coupling body to release the tube. Preferably the end cap has an internally threaded sleeve portion encircling and in screwthreaded engagement with an external thread on the main body. In the latter case said indexing means may be provided between the mouth of the sleeve and portion of the main body beyond said threaded portion. More specifically the indexing means may comprise a radially inwardly directed projection at the mouth of the sleeve and a plurality of cam means disposed around the main body beyond the screwthreaded to define said first and second positions of rotational adjustment of the cap with respect to the sleeve. In one particular arrangement according to the invention the first cam means on the main body may have an inclined cam face engaged by the projection on the sleeve to provide an increasing resistance to relative rotation when the projection encounters the cam in screwing the body parts together and may have a radial face beyond the inclined face with which the projection is engageable to resist unscrewing of the cap from the main body. Furthermore a second cam means may be located on said main body adjacent the first cam means to provide a recess to receive said projection on the sleeve to define said one position of rotation of adjustment of the body parts. Preferably the second cam means has an inclined face opposite the first cam means to lift the projection on the sleeve part over the second cam means as the cap is screwed further onto the main body together towards said second position of the cap/main body. In addition third cam means may be provided on the main body having an inclined face on the side adjacent the first step means to provide a resistance for the projection to define the said second position relative rotation of the body parts. The following is a description of some specific embodiments of the invention, reference being made to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a tube coupling in accordance with the invention including a tube inserted in the coupling; Figure 2 is a sectional view through the coupling of Figure 1 along the line II-II; Figure 3 is a perspective view of the two parts of the coupling body of the coupling of Figure 1; and Figures 4 and 5 are similar views to Figures 3 and 1 showing the coupling in a second locking condition; Figures 6 to 10 are similar views of Figures 1 to showing a first modified arrangement; Figure 11 shows a second modified arrangement; Figures 12 and 13, 14 and 15 show further modified arrangements. Referring firstly to Figure 1 of the drawings, there is shown a tube coupling body indicated generally by reference numeral 10 having a throughway 11 open at one end 12 to receive an end portion of a tube 13. The coupling body comprises a main body 10a and a cap 10b screwed onto the main body as described below. At a location spaced from the open end, the throughway in the main body has a first increase in diameter at a step 14 to provide an enlarged bore 15 in which the end of the tube 13 is a close sliding fit with the end of the tubing engaging the step 14. The throughway has a further increase in diameter at a step 16 to form an enlarged bore 17 in which an 'O' ring seal 18 is located against the step followed by a spacer washer or compression ring 19. The main body 10a of the coupling has an external screw-threaded section 20 extending from the end of the body part followed by a cam section indicated at 21 followed in turn by an encircling radial flange 22. The cap 10b of the coupling body encircles the main body and has an internal screw-threaded section 23 which mates with the screw-thread 20 on the main body. The open end of the cap has a cam section 24 which cooperates with the cam section 21 on the main body as described later. A collet indicated at 25 is mounted in the open end of the coupling body comprising an annular member 26 and resilient arms 27 projecting from the annular member into the throughway of the coupling body and terminating in heads 28. The heads of the collet engage in a tapered cam surface 29 converging towards the end of the coupling body to be compressed against the tube 13 by engagement of the heads with the cam surface to lock the tube in the coupling body. In the position shown in Figure 1, the cap 10a is partially screwed onto the main body 10b and there is a gap between the heads 28 of the collet and the spacer washer 19 in the main body of the coupling which allows the collet to be depressed into the coupling body for release of the tube. Referring now to Figure 2 of the drawings, the cam section 21 of the main body between the thread 20 and the flange 22 is formed with first and second cams 30 and 31 located close together with a gap 32 between the cams. A further, third cam 33 is position at 90° around the main body from the first and second cams. The cams are engaged by an abutment 34 on the inside of the enlarged end of the cap to define two different rotational positions of the cap with respect to the main body. The cam 30 has a shallow incline 40 with which the projection 34 is engageable as the cap is screwed onto the main body. On the other side of the cam there is a radial face 41 which forms an end stop engageable with the projection 34 to resist reverse movement of the cap. If the cap is forced and the abutment 34 is damaged, that will be evident and indicate misuse of the fitting. Spaced opposite the face 41 of the cam 30 is the second cam 31 which has an inclined face 42 adjacent face 41 over which projection 34 can ride when the cap is rotated further from said first position. The cam 33 has angled ramps 43 and 44 on either side thereof. As the cap is rotated towards a quarter of a turn from the first position, the projection 34 engages the first ramp 43 which provides a resistance to further movement as the projection rides up over the cam. When the projection rides just over the peak of the cam, the end of the cap engages the flange 22 as shown in Figure 4. In this position the collet is drawn into the mouth of the main body of the coupling to close up the gap between the collet arms and spacer washer and to firmly clamp the arms of the collet against the tube 13. In this position the collet cannot be depressed into the coupling body to release the tube as will be apparent from Figure 4. When it is required to release the tube from the coupling body, the cap is rotated back through a quarter turn until the projection on the cap engages between the first and second cams on the main body and then the collet can be depressed into the coupling body to release the tube. The function of the cams will best be appreciated from the following description, of events from assembling the cap onto the body to releasing the cap from the "SuperSeal" position. The assembly operator assembles the cap onto the body. The clockwise face of cam 31 offers little resistance and the operator stops rotating the cap once the clockwise face of cam 32 provides resistance. The cap is now in the "Speedfit" condition, and will remain here until the customer/end user wants to change this. The counter-clockwise face of the cam 30 precludes easy removal of the cap from the body. In fact this face will be damaged if the cap is removed thereby providing evidence of tampering. If the user decides to adjust the fitting he/she turns the cap past the nominal resistance of the clockwise face of cam 31 and continues to rotate the cap through a quarter turn past the slight interference of the clockwise face of cam 33. The cap has now compressed the collet, spacer washer and 'O' ring together - thereby creating extra grip and sealing as a "SuperSeal" connection. In addition, any free play in the tube connection is removed and the collet cannot be released accidentally. To release the fitting, the user must first turn the cap counter-clockwise past cam 33 and the slight interference afforded by the counter-clockwise face of cam 31, and hence back to the "Speedfit" position. The tube can now be removed by releasing the collet in the usual way provided by the "Speedfit" coupling. Referring now to a first modified arrangement shown in Figures 6 to 11, the first cam 30 on the main body is replaced by an obliquely angled flexible leg 50 performing the same function as the solid cam 30. The solid cam 31 and 33 may also be replaced by obliquely angled flexible legs. The arrangement is otherwise the same as that of Figures 1 to 5 and operates in the same way. The arrangement shown in Figure 12 is a further modification in which the positions of the cams on the body and cap are reversed. On the tube coupling body, a single obliquely angled leg 51 is formed which could, equally, be a cam of the form 24 provided on the cap of the arrangements of Figures 1 to 5. The cap is formed with a pair of closely spaced cams 52, 53 equivalent to cams 30 and 31 of the arrangement of Figures 1 to 5 and a further circumferentially spaced cam 54 equivalent to cam 33 on the body of arrangement Figures 1 to 5. The arrangement of cams on the cap and resilient leg on the coupling body will define first and second positions of rotation of the cap with respect to the coupling body as previously described. Figures 12 and 13 show a further arrangement in which the cams 30, 31 and 33 (not shown) on the body are engaged by an axially extending flexible leg 55 on the cap to define first and second positions of rotation of the cap on the coupling body as before. Figure 14 shows a further variant in which the coupling body is formed with a flange 60 having raised cams 61 (only one of which can be seen) having a shallow angle ramp 62 at one end and a perpendicular face 63 at the other end. A resilient leg 64 on the cap is engageable with the cams riding up over the ramp and cam with clockwise rotation of the cap and dropping down to the flange 60 beyond face 63 to resist return movement. A similar cam is provided at a spaced location around the flange to provide a second position in which the cap is located with respect to the coupling body. Figure 15 shows yet a further arrangement in which the cap has windows 70 (only one of which can be seen) spaced around the cap and with which an outwardly angled flexible leg 71 on the coupling body is engageable to define the two spaced positions of rotation of the cap with respect to the body.

Claims: A tube coupling comprising a coupling body (10) having a throughway (11) open at one end (12) to receive an end portion of a tube (13), an internal cam surface (29) tapering towards the open end in which a collet (25) is located for locking the tube in the coupling body by engagement with the tapered cam surface, and stop means to limit entry of the collet into the throughway, the coupling body consisting of a main body (10a) the throughway of which receives the end of a tube and contains said stop means to limit insertion of the collet and an end cap (10b) in screwthreaded engagement with the main body containing said open end to the throughway and the tapered cam surface; characterised in that indexing means (24, 30, 31, 33) are provided between the end cap and main body to define different positions to which the cap can be screwed onto the body in a first of which a tube can be inserted into the throughway to be held by the collet and, by depressing the collet (25) into the coupling body, released and from which the cap cannot be unscrewed and in a second of which, reached by screwing the cap further onto the body the collet is engaged with the stop means to prevent the collet being depressed into the coupling body to release the tube. A tube coupling as claimed in claim 1, characterised in that the end cap (10b) has an internally threaded sleeve portion encircling (23) and in screw-threaded engagement with an external thread (20) on the main body (10a). A tube coupling as claimed in claim 2, characterised in that said indexing means (24, 30, 31, 33) are provided between the mouth of the cap and a portion of the main body (10a) beyond said threaded portion (20) on the body. A tube coupling as claimed in claim 3, characterised in that the indexing means comprise a radially inwardly directed projection (24) at the mouth of the cap (10b) and a plurality of cam means (30, 31, 32, 42, 40; 33, 43, 44) disposed around the main body (10a) beyond the screw-thread to define said first and second positions of rotational adjustment of the cap with respect to the sleeve. A tube coupling as claimed in claim 4, characterised in that the first cam means on the main body (10a) has an inclined cam face (40) engaged by the projection (25) on the cap to provide an increasing resistance to relative rotation when the projection encounters the cam in screwing the body parts together and has a radial face (32) beyond the inclined face with which the projection is engageable to resist unscrewing of the cap from the main body. A tube coupling as claimed in claim 4 or claim 5, characterised in that a second cam means is located on said main body (10a) adjacent the first cam means to provide a recess to receive said projection on the sleeve to define said one position of rotation of adjustment of the body parts. A tube coupling as claimed in claim 6, characterised in that said second cam means has an inclined face (43) to lift the projection (24) on the cap part (10b) over the second cam means as the cap is screwed further onto the main body towards said second position of the cap/main body. A tube coupling as claimed in claim 7, characterised in that a third cam means are provided on the main body having an inclined face on the side adjacent the second cam means to provide a resistance for the projection on the cap or vice versa to define the said second position relative rotation of the body parts.

Inventors: GUEST JOHN DEREK, GUEST, JOHN DEREK
Applicants: JOHN GUEST LTD, JOHN GUEST LIMITED
Application year: 1999
Main classification: F16L37
IPC codes: F16L21, F16L37