Plastic retainer for fluid coupling

Abstract: A plastic retainer (26) has a pair of axially spaced cylindrical rings (28,30). Retainer arms (32) for retaining an upset portion (33) of a tube (22) within a housing bore extend from said rear ring (30), and a plurality of webs (46) connect the front and rear cylindrical rings (28,30) of the retainer (26). When a tube (22) is initially inserted into the housing bore, it contacts an inner periphery of the arms (32). The retainer (26) then moves axially forwardly within the bore for a small distance until the forward ring (28) abuts a seal package (36) within the housing (24). Further movement of the retainer (26) is then prevented, and the upset portion (33) of the tube (22) causes the arms (32) to flex radially outwardly at a flex point in the rear ring (30). The upset portion (33) may then move axially beyond the arms (32) into a fully connected position within the housing (24).

Description: This invention relates to a fluid coupling comprising a retainer that securely retains a tube within a housing. Various types of quick connect fluid couplings are known wherein a plastic retainer has two arms which extend radially inwardly to secure a radially greater upset portion of a tube within a housing bore. Generally, the upset portion of the tube is forced inwardly of the housing bore such that it causes the arms to flex radially outwardly. The upset portion then moves axially beyond the arms. The arms move back radially inwardly, and abut the upset portion, preventing tube removal. WO-A-89/09361 discloses a fluid coupling according to the preamble of claim 1, comprising in particular a retainer having a cylindrical axially inner ring at a first axial position and a cylindrical axially outer ring at a second axial position spaced axially outwardly from said first axial position. A pair of arms extend axially inwardly from said outer ring, for engagement of an enlarged diameter portion of a tube. The outer ring and hence the arms extending therefrom are located in fixed relationship with respect to a housing by engagement of formations on the outer ring with corresponding formations on the housing. Correct functioning of the retainer to retain the tube in the housing depends on the accurate location of the outer ring of the retainer with respect to the housing. In this type of quick connect fluid coupling, several competing goals must be met. First, it is desirable that the arms securely retain the tube within the housing, and that a very high force be required to cause the retainer to fail and allow the tube to be removed. To this end, it is desirable to increase the number of arms which abut the upset portion of the tube. Merely increasing the number of arms is not a satisfactory solution, however, because it becomes difficult to ensure that the arms are all positioned at proper axial positions relative to each other. If the arms are misaligned they may not all abut the upset portion of the tube. Further, it becomes difficult to ensure that the retainer body is properly positioned within the housing bore. Because of these reasons the number of arms has typically been limited and plastic retainers have not been utilised in higher pressure connections. To overcome these drawbacks, the present invention proposes a coupling according to claim 1. In a disclosed embodiment of the present invention a plastic retainer retains a tube within a housing bore. The retainer comprises a pair of axially spaced cylindrical rings with a plurality of circumferentially-spaced connecting webs extending between the two rings. Resilient arms are circumferentially-spaced between the webs, and extend from a rear flex ring. The arms abut the upset portion of a tube, and prevent tube removal. The tube is inserted into the bore, and eventually abuts the inner periphery of the arms. The retainer then moves axially forwardly for a relatively small distance until a forward ring abuts a seal package within the housing bore. The forward ring ensures that the retainer is properly orientated and positioned within the housing bore as the tube moves beyond the resilient arms. Further movement of the retainer is prevented, and the upset portion of the tube flexes the resilient arms radially outwardly about the rear flex ring, and moves axially beyond the arms. Since the arms flex at the rear flex ring, and are all interconnected by the rear flex ring, it is ensured that the arms are all properly positioned relative to each other. Thus, the arms all abut the upset portion, preventing tube removal and increasing the strength of the retainer. Due to the improved positioning of the retainer achieved by the spaced forward and rear rings, the inventive retainer can effectively use four arms. The retainer can thus be used in higher pressure applications. Most preferably, the rear flex ring extends for a relatively small radial extent compared to the radial thickness of the arms at a position connected to the rear ring. This improves the flexing of the arm relative to the rear ring. In a most preferred embodiment of the present invention the arm extends radially outwardly of the radially outermost portion of the rear flex ring. These and other objects of the present invention can be best understood from the following specification and drawings, of which the following is a brief description. Figure 1 is an exploded view of an inventive fluid coupling. Figure 2 is a cross-sectional view through an assembled coupling. Figure 3 is a partial end view of a coupling. Figure 4 is a perspective view of a retainer used in a fluid coupling. Figure 5 is an end view of the retainer illustrated in Figure 4; and Figure 6 is a cross-sectional view along line 6-6 as shown in Figure 4. Figure 1 illustrates a fluid coupling 20 for securing a tube 22 within a housing 24. A retainer 26 includes a forward ring 28 and a rear flex ring 30. A bore 29 is formed in forward ring 28. A plurality of arms 32 entered from flex ring 30 and abut a radially greater, or upset portion 33 of tube 22. Retainer 26 has a conical outer surface to facilitate insertion into housing 24. A seal 34 and a steel seal retainer or spacer 36 are positioned in housing 24 axially inwardly of retainer 26. Seal retainer 36 has a flared axially outer end 38. As shown in Figure 2, a plurality of arms 32 abut upset portion 33 to prevent tube removal. Forward ring 28 abuts an axially outer end of flared outer end 38, and a generally conical inner portion 39 of forward ring 28 extends axially inwardly of flared outer end 38. As tube 22 is inserted within housing 24, upset portion 33 contacts an inner peripheral surface on arms 32. Arms 32 have an inner peripheral surface which extends radially inwardly along a direction axially inwardly from flex ring 30. That is, the inner periphery of arms 32 is spaced from a centre axis X of housing 24 by a greater distance at an axial location adjacent flex ring 30 than it is spaced from the same axis at an axially inner end of arms 32. Once upset portion 33 contacts the inner periphery of arms 32, retainer 26 may move further axially inwardly for a relatively small amount until forward ring 28 contacts flared outer end 38 of seal retainer 36. Further axial movement of retainer 26 is now prevented. There is a small axial clearance between housing 24 and retainer 26 to allow for the axial movement of retainer 26, and the outward flexing of arms 32. As tube 22 continues to be inserted, upset portion 33 will cause arms 32 to flex radially outwardly approximately about a point 42 in rear flex ring 30. Upset portion 33 will eventually move axially beyond arms 32. Arm 32 flex back radially inwardly and tube 22 is fully connected within retainer 26. Since forward ring 28 positions retainer 26 by being forced against seal package 36, it is ensured that retainer 26 is properly orientated and positioned within housing 24. Further, since rear flex ring 30 connects each arm 32, it is ensured that the arms 32 are all properly axially positioned relative to the other, and that they all abut upset portion 33. Rear ring 30 is cylindrical and extends axially outwardly of an entrance bore 43 in housing 24. Arms 32 are spaced from an inner wall 44 that defines bore 43. Thus, rear ring 30 and arms 32 do not abut any portion of housing 24, or have a positioning function. Figure 3 is a view looking inwardly of housing 24 prior to the insertion of tube 22. As shown, arms 32 extend radially inwardly of bore 43 to housing 24. Rear flex ring 30 is received within bore 43, and bore 29 in forward ring 28 for receiving the axially inner end of tube 22 is positioned axially inwardly of bore 43. Figure 4 is a perspective view of plastic retainer 26. As shown, a plurality of webs 46 extend axially between forward ring 28 and rear flex ring 30, connecting the two. Arms 32 are integrally formed with rear ring 30, such that arms 32 flex about point 42. Arms 32 extend radially outwardly from the radially innermost portion of ring 30, and beyond the radially outermost portion of ring 30. Arms 32 are solid. As shown in Figure 5, webs 46 extend over a smaller circumferential extent at the radial inner portions than they do at radially outer portions. Arms 32 have a curved inner periphery such that they conform to the outer surface of tube 22. Figure 6 is a cross sectional view along line 6-6 as shown in Figure 4. Arms 32 extend radially beyond the radially outermost portion of rear flex ring 30, and then extend radially inwardly. In a most preferred embodiment of this invention, the plastic retainer was formed of a material available under the trade mark Carilon™, Code P1000, which is a product available from Shell Chemical. Its generic name is aliphatic polyketone, or APK.

Claims: A fluid coupling (20) comprising a housing (24) defining a bore with an axis extending inwardly into said bore from an entrance (43) to said bore; a seal package (36) positioned within said bore; a retainer (26) having a cylindrical axially inner ring (28) at a first axial position, and a cylindrical axially outer ring (30) at a second axial position spaced axially outwardly from said first axial position, a plurality of arms (32) extending axially inwardly from said outer ring (30), said arms (32) having an inner periphery spaced by a greatest radial distance from said axis at a location adjacent said outer ring (30), and each said arm inner periphery extending radially inwardly to an axially inner end spaced from said axis by a radial dimension that is less than said greatest radial dimension; and a tube (22) received within said bore, said tube (22) having a first outer diameter over the majority of an axial length, and a greater diameter portion (33) formed at one axial position of said tube (22), said greater diameter portion (33) being spaced axially inwardly of said arms (32) such that said arms (32) retain said tube (22) within said bore; said coupling being characterised in that said housing entrance (43) is of a first inner diameter at a position leading into said bore, said outer ring (30) having an outer diameter slightly less than said first diameter of said entrance (43), and said outer ring (30) extending axially outwardly of said entrance (43), the outer ring (30) defining a flex ring to which said arms (32) are flexibly attached, the arms (32) having an outer periphery adjacent the outer ring (30) which extends radially outwardly of said first inner diameter when the inner ends of the arms (32) engage said first outer diameter of the tube (22). A fluid coupling (20) according to claim 1, characterised in that a plurality of circumferentially, spaced webs (46) extend axially between said inner and outer rings (28,30) to connect said rings. A fluid coupling (20) according to claim 1 or 2, characterised in that there are at least four of said arms (32). A fluid coupling (20) according to any one of the preceding claims, characterised in that said retainer (26) is formed of a plastic material. A fluid coupling (20) according to claim 4, characterised in that said plastic material is an aliphatic polyketone. A fluid coupling (20) according to any one of the preceding claims, characterised in that said outer ring (30) is of a first radial thickness, and said arms (32) are of a greater radial thickness than said first radial thickness at a location axially adjacent said outer ring (30). A fluid coupling (20) according to any one of the preceding claims, characterised in that a conically tapered portion (39) extends from said inner ring (28) in a direction away from said outer ring (30).

Inventors: MCNAUGHTON JAMES, WALKER DONALD C, MCNAUGHTON, JAMES, WALKER, DONALD C.
Applicants: BUNDY CORP, BUNDY CORPORATION
Application year: 1992
Main classification: F16L37
IPC codes: F16L37