Tube couplings

Abstract: The disclosure relates to a tube coupling comprising a coupling body (11), having a throughway (12) open at one end (13) to receive a tube (50). A first collet (24) is mounted in the throughway to grip the tube and resist extraction of the tube from the throughway. A cap (32) is mounted to extend over the open end of the coupling body to house second collet (36) arranged head to head with the first collet. The second collet is engageable with an annular abutment (51) on the tube to retain the tube in the coupling body. A single release means in the form of plunger elements (42) is provided on the cap to act on the collets to allow release of the tube from the coupling body.

Description: This invention relates to tube couplings and particularly, though not exclusively applicable to couplings for metal tubing such as in fuel or brake fluid lines as used in motor vehicles. EP-A-0255368 discloses a tube coupling comprising a body having a throughway open at one end to receive a tube, a tapered surface in the throughway reducing towards said one end, and a collet extending into the throughway through said one end having resilient fingers engaging with the cam surface to grip and hold a tube in the throughway. An end cap is fitted to the coupling body extending over the open end of the throughway having a device for engaging the end of the collet projecting from the throughway to press the collet into the throughway and release the gripping action of the resilient fingers on the tube. US-A-5161834 discloses a fluid connector system comprising a housing having a fluid port, a cartridge permanently insertable in the fluid port, a conduit detachably inserted in the cartridge , the cartridge comprising a housing insertable in the fluid port and having an opening therethrough communicable with the fluid port, and a retainer disposed in the opening and cooperable with the conduit for detachably securing the conduit in the cartridge in a coupling condition therewith when the conduit is inserted in the opening, a release member mounted in the cartridge housing and cooperable with the retainer for releasing the conduit to allow it to be removed from the cartridge into an uncoupling condition. FR-A-2217627 shows a further fluid connector system for locking a conduit in a housing. EP-A-0546511 discloses a still further arrangement for locking a tube in a housing. This invention provides a tube coupling for releasably gripping a tube comprising a coupling body having a throughway open at one end to receive a tube and tube gripping means disposed in the throughway to grip and hold the tube and to resist extraction of the tube from the throughway and a release means on the coupling body for releasing the tube gripping means to allow a tube to be extracted from the coupling body; wherein separate detent means are mounted in the coupling body adjacent to the tube gripping means for engaging an annular abutment on the tube to retain the tube in the coupling body, and said release means is a common release means disposed on the coupling body for releasing both the detent means and the tube gripping means to enable the tube to be extracted from the tube coupling. Preferably the tube gripping means includes grip relieving means projecting from the open end of the throughway for releasing the tube gripping means by being depressed into the throughway. It is also preferred that the coupling body has an enclosure for the open end of the coupling body, said enclosure having an aperture through which a tube extends when it is inserted into the throughway, that the detent means are located in the enclosure, and in that said common release means is disposed on the enclosure. In the latter arrangement the detent means may comprise a collet which is axially moveably disposed between an end wall of the enclosure and an end of the coupling body, the collet having an annular head engageable with said grip relieving means projecting from the coupling body, said collet including radially resilient fingers which project towards the end wall of the enclosure and which snap over the annular abutment on a tube when the tube is inserted into the coupling body. More specifically the end wall of the enclosure may have an inwardly facing abutment surface with which the ends of the fingers are engageable to hold the fingers against radial outward movement and thereby to lock the tube in the coupling body, whereby the action of pulling the tube in a direction outwardly of the coupling body draws the grip relieving means outwardly of the coupling body until the tube gripping means grips and holds the tube and the resulting movement of the collet with the grip relieving means causes the radially resilient fingers to engage with the abutment surface. Further, the common release means may comprise means to move the collet into engagement with the grip relieving means to disengage the ends of the radially resilient fingers from the inwardly facing abutment surface and to move the grip relieving means inwardly into the tube coupling body to enable a tube to be extracted from the coupling body. In either of the latter arrangements the inwardly facing abutment surface may extend around the enclosure aperture. In accordance with a further feature of the invention the annular head may have an encircling angled ramp face on the side of the collet which is disposed away from the coupling body, a plurality of depressable plunger elements disposed on the enclosure, said plunger elements having angled cam faces engageable with the angled ramp face to move the collet towards the coupling body upon depression of the plunger elements. In the latter arrangement the plunger elements may be formed integrally with flexible webs which are disposed on a wall of the enclosure. In any of the above arrangements said tube gripping means/grip relieving means may comprise a second collet having a head disposed outside the coupling body and a plurality of resilient fingers projecting into the coupling body and the throughway has an internal cam surface which tapers towards the open end of the throughway, the resilient fingers being engageable with the internal cam surface whereby the fingers are depressed radially inwardly to engage and grip a tube upon movement of the second collet outwardly of the throughway and to release the tube upon movement of the second collet inwardly of the throughway. In the latter construction an annular cam element may be disposed in the throughway of the coupling body, the ends of the resilient fingers of the second collet engaging the annular cam element when the second collet is depressed into the throughway to thereby expand the resilient fingers and release the tube. In yet a further arrangement according to the invention the tube gripping means may comprise a grab ring mounted in the throughway and a sleeve extending from the grab ring through the open end of the throughway whereby depression of the sleeve causes the grab ring to cease gripping and holding the tube. 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 sectional view through a tube coupling; and Figures 2 to 5 illustrate step by step insertion, engagement and release of a tube in the coupling; Referring to Figure 1 of the drawings there is shown a tube coupling indicated generally at 10 comprising a moulded coupling body 11 having a throughway 12 which has an open end 13 to receive a tube to be secured and sealed in the body. The coupling body includes a central portion 14 the internal diameter 15 of which corresponds generally to the outer diameter of the tube to be secured in the coupling body. The central portion 14 terminates in an annular shoulder 16 facing towards the open end of the body with which an end of a tube to be located in the body is engageable. The central portion 14 of the body gives way to an enlarged diameter portion 17 and a step 18 in which a pair of O-ring seals 19 are located with a washer 20 disposed between the seals to seal with the outer surface of the tube to be located in the body. The enlarged diameter portion 17 of the body gives way to a further increase diameter portion 21 having an open end 22 in which a separate moulded annular insert 23 is secured which provides the end opening 13 to the throughway referred to above. A collet 24 is mounted in the open end of the throughway comprising an annular head 25 disposed outside the throughway and a plurality of resilient fingers 26 projecting into the throughway and terminating in heads 27. The collet is moulded in plsatics and the heads 27 have metal barbs 28 projecting through the heads to bear against and grip the surface of a tube extending through the collet. The annular insert 23 is formed with an internal tapered cam surface 29 converging towards the open end 13 provided by the insert with which the heads 27 of the collet are engageable when the collet is drawn in a direction outwardly of the throughway to cause the heads to be pressed inwardly into gripping engagement with a tube passing through the collet. Conversely, displacement of the collet inwardly into the throughway releases the heads from the tapered cam surface to release the gripping action of the heads on the tube. To facilitate release of the heads from the tube a ring 30 is mounted in the enlarged part of the coupling body formed with an external tapered cam surface 31 facing toward the heads of the collet. Displacement of the collet into the throughway causes the heads to engage the cam face 31 to expand the heads outwardly away from the surface of the tube to facilitate release of the tube from the coupling body. The coupling body 11 has a cap or enclosure 32 comprising an annular wall 33 secured to the enlarged diameter portion 21 of the coupling body and an end wall 34 spaced from the end of the coupling body 11. The end wall 34 has an aperture 35 through which a tube to be engaged in the coupling body is inserted. The enclosure 32 contains a second collet 36 having an annular head 37 and resilient fingers 38 projecting from the head. The second collet is mounted head-to-head with the first collet so that the resilient fingers 38 of the second collet project away from the coupling body towards the end wall 34. The ends of the resilient fingers 36 of the second collet have inturned heads 39 which are engageable with a bevel 40 formed around the aperture 35 of the inside of the end wall 34 so that when the heads 40 are engaged with the bevel, they are prevented from expanding radially. The side of the head 37 of the second collet facing towards the end wall 34 has an angled cam face 41 facing towards the end wall 34. The encircling wall 33 of the enclosure is formed with apertures at diametrically opposite locations in the enclosure and plunger elements 42 are connected integrally with the wall of the enclosure by flexible webs 43 to project into the enclosure. The plunger elements have angled faces 44 engageable with the cam face 41 on the head 37 so that depressing the plungers radially inwardly deflects the second collet towards the head of the first collet releasing the heads 39 of the second collet from the bevel 40 on the end wall of the enclosure to allow the fingers to expand. Once the clearance between the heads of the collets has been taken up, continuing to depress the plungers 42 causes the first collet to be driven into the throughway to release the fingers of the first collet from a tube passing through the collet as described earlier. Thus the plunger 42 provides one release means for both the first and second collets. Referring now to Figures 2 to 5 of the drawings, there is shown the sequence of operations of the coupling when a tube to be gripped in the coupling is to be inserted. The tube is indicated at 50 and it should be noted that the tube has an integral rounded encircling abutment 51 formed part-way from the end of the tube specifically for engageable by the second collet of the coupling. In Figure 2, the end of the tube is shown inserted through the aperture 35 of the enclosure on the coupling body and through the tube collet. As can be seen, the heads 27 of the collet within the coupling body have separated to accommodate the tube and are engaged with the tapered cam surface 29 so that the end of the tube is already gripped at this stage and any attempt to draw the tube would be resisted by the collet. Figure 3 shows the tube further inserted into the coupling body so that the end of the tube is located in the first of the O-ring seals 19. Figure 4 shows the tube fully inserted into the coupling body with the end of the tube in the central portion 14 of the coupling body. The tube is in fact inserted until the end of the tube engages the shoulder 16. When the annular abutment 51 on the tube engages the heads 40 of the second collet, the second collet will be displaced from the position shown in Figure 3 until the collets come head-to-head as shown in Figure 4 and the collets are moved inwardly together until the heads 39 of the second collet are clear of the bevel 40 and the heads can then separate to allow the abutment 51 on the tube to pass through. Once the abutment has passed through, the heads close around the abutment 51 as shown in Figure 4. A small movement of the tube outwardly of the coupling body as indicated by the gap between the shoulder 16 and end of the tube illustrated in Figure 4 draws the first collet outwardly of the coupling body sufficiently to cause the heads 27 of the collet to be deflected inwardly by the tapered cam surface 29 into positive gripping engagement with the tube and at the same time the heads 39 of the second collet are engaged in the bevel face 40 on the end wall of the enclosure to lock the heads firmly inwardly against the abutment 51. The tube is therefore doubly locked to the coupling body. To release the tube from the coupling body, the plungers 42 on the enclosure are depressed inwardly as illustrated in Figure 5 to draw the first collet towards the coupling body thereby releasing the heads 39 from the bevel face 40 and at the same time to depress the first collet inwardly into the coupling body to engage the heads 27 of the collet with the annular cam face 31 to release the heads from the tube which can then be extracted from the coupling body. The arrangement thus provides a coupling for a tube which is effected simply by pushing the tube into the coupling body which grips, clips and seals the tube in place so that even if the main gripping collet in the coupling body should fail for any reason, the tube will still be held by the second collet in sealed engagement in the coupling body. At the same time, the tube can readily be extracted from the coupling body by simply depressing the plungers on the enclosure which enable both collets to be released from the tube. In a modification of the above arrangement the collet 25 and tapered cam surface 29 are replaced by a grab ring mounted in the throughway to receive and grip a tube with a sleeve extending from the grab ring through the open end of the sleeve depressing of which by the head 37 of the second collet depresses the sleeve into the throughway to release the grab ring and thereby allow extraction of the tube.

Claims: A tube coupling for releasably gripping a tube comprising a coupling body (11) having a throughway (12) open at one end (13) to receive a tube (50) and tube gripping means (24) disposed in the throughway to grip and hold the tube and to resist extraction of the tube from the throughway and a release means (42) on the coupling body for releasing the tube gripping means to allow a tube to be extracted from the coupling body; wherein separate detent means (36) are mounted in the coupling body adjacent to the tube gripping means (24) for engaging an annular abutment (51) on the tube to retain the tube in the coupling body, and said release means (42) is a common release means disposed on the coupling body (11) for releasing both the detent means (36) and the tube gripping means (24) to enable the tube to be extracted from the tube coupling. A tube coupling as claimed in claim 1, characterised in that the tube gripping means (24) includes grip relieving means (25) projecting from the open end of the throughway (12) for releasing the tube gripping means by being depressed into the throughway. A tube coupling as claimed in claim 1 or claim 2, characterised in that the coupling body (11) has an enclosure (32) for the open end of the coupling body, said enclosure having an aperture (35) through which a tube extends when it is inserted into the throughway, in that the detent means (36) are located in the enclosure, and in that said common release means (42) is disposed on the enclosure. A tube coupling as claimed in claim 3, characterised in that the detent means (36) comprises a collet (37,38) which is axially moveably disposed between an end wall (34) of the enclosure and an end (23) of the coupling body, the collet having an annular head (37) engageable with said grip relieving means (25) projecting from the coupling body, said collet including radially resilient fingers (38) which project towards the end wall of the enclosure and which snap over the annular abutment (57) on a tube (50) when the tube is inserted into the coupling body. A tube coupling as claimed in claim 4, characterised in that the end wall (34) of the enclosure has an inwardly facing abutment surface (40) with which the ends (39) of the fingers (38) are engageable to hold the fingers against radial outward movement and thereby to lock the tube in the coupling body, whereby the action of pulling the tube in a direction outwardly of the coupling body draws the grip relieving means outwardly of the coupling body until the tube gripping means grips and holds the tube and the resulting movement of the collet with the grip relieving means causes the radially resilient fingers to engage with the abutment surface. A tube coupling as claimed in claim 5, characterised in that the common release means (42) comprises means (44) to move the collet (32) into engagement with the grip relieving means (25) to disengage the ends of the radially resilient fingers from the inwardly facing abutment surface and to move the grip relieving means inwardly into the tube coupling body to enable a tube to be extracted from the coupling body. A tube coupling as claimed in claim 5 or claim 6, characterised in that the inwardly facing abutment surface extends around the enclosure aperture. A tube coupling as claimed in claim 6 or claim 7, characterised in that the annular head has an encircling angled ramp (41) face on the side of the collet which is disposed away from the coupling body, a plurality of depressable plunger elements disposed on the enclosure, said plunger elements having angled cam faces engageable with the angled ramp face to move the collet towards the coupling body upon depression of the plunger elements. A tube coupling as claimed in claim 8, characterised in that the plunger elements (42) are formed integrally with flexible webs (43) which are disposed on a wall of the enclosure (32). A tube coupling as claimed in any of the preceding claims, characterised in that said tube gripping means and said grip relieving means comprise a second collet (26) having a head (25) disposed outside the coupling body (11) and a plurality of resilient fingers (27) projecting into the throughway (12) which has an internal cam surface (29) which tapers toward its open end, the resilient fingers being engageable with the internal cam surface whereby the fingers are depressed radially inwardly to engage and grip a tube upon movement of the second collet outwardly of the throughway and to release the tube upon movement of the second collet inwardly of the throughway. A tube coupling as claimed in claim 10, characterised in that an annular cam element (30,31) is disposed in the throughway (12) of the coupling body, the ends of the resilient fingers of the second collet engaging the annular cam element (30) when the second collet is depressed into the throughway to thereby expand the resilient fingers and release the tube. A tube coupling as claimed in any of claims 1 to 9, characterised in that the tube gripping means comprises a grab ring mounted in the throughway and a sleeve extending from the grab ring through the open end of the throughway whereby depression of the sleeve causes the grab ring to cease gripping and holding the tube.

Inventors: GUEST JOHN DEREK, GUEST, JOHN DEREK
Applicants: GUEST JOHN D, GUEST, JOHN DEREK
Application year: 1993
Main classification: F16L37
IPC codes: F16L37