GB2174468A - Quick connect fitting - Google Patents

Abstract

A push-in style fitting incorporates an annular piston disposed intermediately of a collet and a seal member within a bore of the fitting. The piston includes a radial surface for pressing against the seal, and includes a cammed bearing surface engageable with a mating cammed bearing surface on the collet. After a tubular member has been inserted into the fitting, axially extending parabolically-shaped projections integral to the internal circumference of collet bite into the tubular member, whereby whenever the tubular member is subjected to an axial pull tending to remove the member from the fitting, the collet will bear against the piston thereby pressing the radial surface thereof against the seal. This action will tend to axially constrict the seal between the piston and an internal wall of the fitting to balloon the seal radially inwardly against the tubular member with a force proportional to the amount of the axial pull on the tubular member. The result is the enhancement rather than the deterioration of sealing effectiveness whenever the tubular member is subjected to an axial load. <IMAGE>

Description

SPECIFICATION Quick connect fitting Background of the invention This invention relates to quick connect fittings for tubular members made of plastics and other synthetic resins. More particularly, the invention relates to improvements of push-in style fittings for resilient tubular members subjected to axial loads.

Numerous prior art fittings of the push-in style include collets disposed for gripping and retaining resilient tubular members inserted into the fittings.

Such fittings also include sealing media for prevention of leakage of gases and liquids conveyed through the members. However, prior art fittings have not contained adequate safeguards against leakage of associated sealing members whenever axial loads are imposed upon the resilient tube fitting assemblies. When such resilient tubular members are subjected to axial loads, they tend to momentarily undergo elastic reduction in wall thickness, or what is commonly referred to as "necking down". To the extent that there is no compensating factor for such wall thickness reduction, leakage tends to occur around the sealing media which, depending on circumstances, can have costly ramifications.

Summary of the invention The present invention provides a built-in compensation for the necking down phenomenon which occurs when a resilient tubular member is subjected to an axial pulling force.

In a preferred form, the present invention includes an annular piston disposed intermediately of a collet and an elastomeric seal member, the piston including a radial surface disposed for contacting and pressing against the seal. The piston also includes a cammed bearing surface engageable with a like mating surface on the collet, whereby when the tubular member is subjected to an axial pulling force, the collet will bear against the piston which in turn will press against the seal to cause same to balloon into the tubular member body. Also in the preferred form, the piston and the seal are both piloted within a single one of several stepped bores within the fitting, and thus the seal is at all times circumferentially retained within the same bore as the piston for greater effectiveness.

Also in a preferred form, the collet includes a plurality of integral teeth circumferentially spaced apart about the interior surface of the collet. Each tooth defines an axially oriented parabolicallyshaped body which projects inwardly and terminates in a semi-circular planar surface. Each of the latter tooth surfaces faces the direction of insertion of the tubular member for counteracting forces tending to remove the tube from the fitting. In one preferred form, the planar surfaces are disposed in at least two planes.

Brief description of the drawings Figure 1 is a cross sectional view of a preferred embodiment of the quick connect fitting of the present invention; Figure 2 is a full end view of an annular collet utilized in the preferred embodiment of Figure 1; Figure 3 is a view of the collet taken along lines 3-3 of Figure 2; and Figure 4 is a cross sectional view of an alternate preferred embodiment of the quick connect fitting of the present invention.

Detailed description of preferred embodiments A quick connect fitting 10 of the push-in style is shown generally in Figure 1. The fitting includes a first annular body 12, and a second annular body 14 mateable with the first. In the presently preferred embodiment, the second annular body defines a nut threadably engageable with the first annular body 12. The body 12 and nut 14 share a common center line, as shown at "a-a", which is broken to depict the view of the fitting 10 prior to insertion of a tubular member 16 in the top half, and a post-insertion view in the bottom half. The tubular member 16 is made of a resilient material, preferably of a plastic or other synthetic resin. The quick connect fitting 10 incorporates a conventional eyelet 18 having a bell 19 forming its innermost insertion extremity 21.The fitting 10 also includes a collet 20 which contains front and rear axially oriented teeth 22 and 24, which are integral with the collet. The annular body 12 has a multiply stepped bore defining four individual bores 30, 32, 34 and 36, having successively reduced diameters from the outermost bore 30 to the innermost bore 36. The outermost bore 30 contains an elastomeric O-ring seal 26 and an annular piston 28, the latter of which is intermediately positioned between the collet 20 and the seal 26.

The interface between the bores 30 and 32 comprises a first shoulder against which an insertion limit of the piston 28 is effected. The bores 32 and 34 comprise a second shoulder 40 at their interface which provides an end-wall against which rests the collet 20. It will be appreciated by those skilled in the art that (referring to the top half of Figure 1), upon insertion in the direction "A", the tubular member 16 will slide through the nut 14 over the eyelet 18 past the seal 26, beyond the piston 28, and over the outwardly facing portions of the teeth 22 and 24. However, upon application of an axial force to the tubular member 16 in direction opposite the direction "A", semi-circular planar surfaces 56 (Figure 2) on the teeth 22 and 24 will bite into the exterior surface of the tubular member 16, to counteract the axial force on the member 16.

Moreover, it will be seen that such an effort will tend to pull the collet 20 outwardly or opposite the inward direction "A", wherein a mating cam surface 52 defining the internal circumference of the annular piston 28 will engage a cam surface 54 on the external circumference of the collet, whereby the collet will bear against the piston urging a radial surface 50 on the piston to contact and press against the seal 26 compressing the seal against an interior inwardly facing wall 48 on the nut 14.

Referring to the lower half of Figure 1, to the ex tent that after insertion of the member 16 there will be no available expansion volume for distention of the 0-ring, the latter will be forced to balloon radially against the exterior wall of the resilient member 16. The net result is that for a given axial force tending to pull the tubular member 16 out of the fitting 10, the collet and piston members will operate in concert to effect a directly proportional ballooning of the seal 26 to more effectively seal the tubular member during the afore-described necking down phenomenon. This presents a significant contrast to prior art fittings for resilient tubular members, which tend to leak under application of cyclical axial pulling forces.

The lower half of Figure 1 also depicts an optional washer retainer member 42 which may be made of a stainless steel or other inert material.

The member 42 is positioned between the end-wall 40 and the collet 20, and offers an optional additional retention means beyond that afforded by the teeth 22 and 24 of the collet 20 for selected heavy duty applications. In a preferred form, the member 42 contains radially inwardly extending fingers 43 angularly disposed in the direction "A".

Referring now more particularly to Figures 2 and 3, a preferred embodiment of the collet 20 is shown in greater detail. The collet 20 has an annular body which includes a circumferentially extending interior surface 60 from which the rear and front teeth 22 and 24 extend. In the preferred form as depicted in Figures 2 and 3, the teeth 22 and 24 are an integral part of the collet body, which is of a tough synthetic resin material. Referring specifically to Figure 3, it will be apparent that each tooth is circumferentially spaced apart from adjacent teeth, and defines an axially-oriented parabolicallyshaped body which projects radially inwardly (Figure 2), and terminates in a semi-circular planar surface 56.As was previously noted, the inwardly directed planar surfaces 56 on the teeth are arrayed in two distinct planes, 62 and 64 (Figure 3), the teeth 24 coterminous with the former, teeth 22 with the latter As also noted, the semi-circular planar surfaces face inwardly, or in the direction "A" for effectively biting into the exterior surface of the tubular member 16 for counteracting axial forces tending to remove the member 16 from the fitting 10.

In a preferred form, the collet (Figure 2) includes a gap 58 which permits it to be sized to tightly engage the next-to-outermost bore 32. The piston 28 may optionally also be of a split construction, however, although the latter is not the case in the presently preferred embodiment.

The interface between the innermost bore 36 and the next-to-innermost bore 34 comprises a third shoulder 44 which provides an insertion limit for the extremity 21 of the eyelet 18, by providing a pilot surface for the bell 19 thereof. The fitting 10 also includes a nipple 46 at its leftward end which has a threaded exterior for coupling to an operational member, not shown, such as an air brake control valve assembly.

Finally, Figure 4 represents an alternate preferred embodiment of a quick-connect fitting 10' which contains a second annular body 14' mated to the first annular body 12'. In the embodiment of Figure 4, the second annular body 14' is a clip-on type of fitting instead of the conventional screw-on type of nut 14 as utilized in the fitting 10 of Figure 1. The clip-on fitting 14' includes a plurality of barbs 70 which extend circumferentially thereabout and clip into a mating plurality of recesses 72 within the body 12'. The clip-on fitting 14' is made of a stamped brass or steel construction, and includes an interior wall 48' which is analagous to the interior wall 48 of the embodiment of Figure 1.

The fitting 10' also includes a stamped brass or steel annular piston member 28', also analagous to the machined or cast piston member 28 of Figure 1. Similarly, the annular piston 28' includes a cammed surface 52' against which the collet 20' may bear to urge same into the O-ring seal 26'. In all other respects, the embodiment of the fitting 10' of Figure 4 is similar to the fitting 10 of Figure 1.

Although only two generally preferred embodiments have been described and shown herein, the following claims are envisioned to cover other numerous alternative embodiments which fall within the spirit and scope of the present invention.

Claims (18)

1. In a push-in style fitting provided for locking insertion of one end of a resilient tubular member, said fitting including an annular body, an eyelet disposed within said body, a nut threadably engageable with said body, said nut including a radially extending internal wall, a collet including means for retaining said tubular member within said fitting, and an annular elastomeric seal supported against said internal wall; an improvement comprising: an annular piston disposed intermediately of said collet and said seal, said piston having a radial surface thereon disposed for pressing against said seal, said piston having a cammed bearing surface engageable with a mating cammed surface on said collet, whereby when said tubular member is subjected to an axial force tending to remove same from said fitting, said collet bears against said piston urging said radial surface of said piston against said seal to press said seal between said piston and said internal wall thereby displacing said seal radially inwardly against said tubular member with a radial force directly proportional to the amount of said axial force.

2. The fitting of Claim 1 wherein said annular body further comprises multiple stepped bores therethrough, wherein both said piston and said seal are piloted in a single one of said bores.

3. The fitting of Claim 2 wherein said bores become smaller in the direction of insertion of said tubular member, and wherein said single bore in which said piston and seal are piloted comprises the largest and outermost bore in said body, wherein said outermost bore and said next-adjacent bore define a shoulder at the interface thereof, said shoulder comprising an innermost axial insertion limit for said piston.

4. The fitting of Claim 3 wherein said means for retaining said tubular member comprises a plurality of teeth circumferentially spaced apart about the internal circumference of the collet, each of said teeth defining an individual axially extending parabolically-shaped projection, each projection extending radially inwardly and terminating in a semi-circular planar surface facing the direction of insertion.

5. The fitting of Claim 4 wherein said tubular member comprises a plastic resin material.

6. The fitting of Claim 5 wherein said parabolically-shaped projections are arranged in at least two planes within said collet.

7. The fitting of Claim 6 wherein said collet defines a gap in one portion of the annular body thereof.

8. A fitting disposed for locking insertion ofsone end of a resilient tubular member, said fitting comprising a first annular body including multiple stepped bores therethrough, an eyelet piloted within a first bore of said first annular body, a retention collet including means for retaining said tubular member positioned within a second bore of said first annular body, a second annular body rigidly affixed to said first annular body, said second annular body including a radially extending internal wall, and an annular elastomeric seal supported against said internal wall, an annular piston disposed intermediately of said collet and said seal, said seal and piston sharing a third bore of said first annular body, said piston including a radial surface disposed for pressing against said seal, said piston having a cammed bearing surface engageable with a mating cammed bearing surface on said collet, said second bore of said collet and said. third bore of said piston comprising an interface defining a shoulder effective to limit axial movement of said piston in the direction of said insertion of said tubular member.

9. The fitting of Claim 8 wherein said second bore of said collet comprises an end-wall, said fitting further comprising a washer retainer member interjacent said collet and said end wall, said washer retainer including radially inwardly extending fingers angularly disposed in the direction of insertion of said tubular member.

10. The fitting of Claim 9 wherein said tubular member is of a resilient synthetic resin material.

11. The fitting of Claim 10 wherein said collet includes a radially extending gap through the body thereof.

12. The fitting of Claim 11 wherein said collet defines a plurality of axially extending parabolically-shaped projections circumferentially arranged about the internal diameter of said collet, each of said projections extending radially inwardly and terminating in a semi-circular planar surface facing the direction of insertion of said tubular member.

13. In a push-in style fitting provided for locking insertion of one end of a resilient tubular member, said fitting including an annular body, an eyelet disposed within said body, a nut threadably engageable with said body, said nut including a radially extending internal wall, and an annular elastomeric seal supported against said internal wall; an improvement comprising: means disposed circumferentially about said eyelet for retaining said tubular member within said fitting, and means acting in concert with said retention means for bearing against said seal to press said seal against said internal wall thereby displacing said seal radially inwardly against said tubular member with a force directly proportional to an axial force tending to remove said tubular member from said fitting.

14. A fitting disposed for locking insertion of one end of a resilient tubular member, said fitting comprising a first annular body, a second annular body adapted for mating engagement with said first annular body, said first annular body including a collet comprising a plurality of integral teeth circumferentially spaced apart about the interior thereof, each tooth defining an axially oriented parabolically-shaped body which projects inwardly and terminates in a semi-circular planar surface.

15. The fitting of Claim 14 wherein said teeth are arranged in at least two planes within said collet.

16. The fitting of Claim 15 wherein said collet comprises a synthetic resin material.

17. The fitting of Claim 16 wherein said collet defines a radially extending gap through one portion thereof.

18. A fitting substantially as described herein with reference to, and as shown in, the accompanying drawings.