Fluid coupling having stepped synchronised threads

Abstract: A fluid coupling is disclosed having a first pipe member (12) and a second pipe member (14). The first pipe member (12) has an externally threaded end (22) with synchronised thread portions (24,26). The second pipe member (14) is configured to be received within the first pipe member (12). The coupling further includes a nut (20) slidably and rotatably fitted around the circumference of the second pipe (14). The nut (20) is internally threaded with a pair of synchronised threaded portions (42,44) for mating engagement with the threaded portions (24,26) of the first pipe member (12).

Description: The present invention relates generally to fluid couplings. More particularly, the present invention relates to a fluid coupling for joining two pipe members, the coupling including a swivel nut having stepped, synchronised threads. Many different types of fluid couplings are known for joining together two pipe members through which a fluid flows. Spring lock couplings are one known type in which a radial spring disposed within a cage assembly securely holds one pipe member to a second. O-rings typically seal the connection between the pipes to prevent leaking. Another type of coupling involves placing a flared end of one pipe member into a second and threading the pipes together with a male nut/female nut assembly. In this known coupling, the female nut is threaded over the male nut and rotated a number of times until tightened. The female nut can be secured directly to the pipe and then rotated to secure the connection, or the nut can rotate freely about the pipe so that the nut alone rotates. However, in this type of coupling, a large number of revolutions or turns of the nut must be made to securely tighten the pipes together. In the ever-decreasing engine compartment of an automobile, it may be difficult to rotate the nut many times. Furthermore, the ergonomics of rotating the nut a large number of times is undesirable. Therefore, it would be advantageous to provide a coupling which overcomes the above-described problems. It is an object of the present invention to provide a coupling which reduces the number of rotations required to secure two pipe members together leak-free and still provide adequate holding strength between the pipes. The patent specification CH 352 888A describes a method of coupling two pipes of synthetic material including forcing a tapered ring co-axially into one end of each of the pipes to cause the pipes to expand and present an external shoulder. The ends of the pipes are then inserted into a coupling piece and held in place by internally threaded nuts that mate with external threads on the coupling piece. The nuts press against the external shoulder on each pipe to hold it in place within the coupling piece. The patent specification DE 24 864 C describes a pipe coupling in which a pipe member has an end portion that is externally threaded over two sections. The two sections are of different diameter and the outermost section is of the lesser diameter. An internally threaded nut engages the larger diameter section of the pipe and a second pipe is threaded onto the lesser diameter section. The patent specification US-A-2 006 520 describes a casing joint that includes inter-fitting tubular members of which one is externally threaded and the other is internally threaded. The joint is made by threading one of the tubular members into the other. A first section of the threads is of larger diameter than the other. According to the present invention, there is now provided a fluid coupling comprising a first pipe member having an externally threaded end portion, said threaded end portion having a first externally threaded portion of predetermined diameter extending a predetermined distance and a second externally threaded portion having a predetermined diameter greater than the diameter of said first threaded portion and extending axially adjacent thereto so as to form a stepped portion, the threaded portion extending further from the pipe member than the threaded portion; a second pipe member having a first end portion of predetermined length and diameter and configured to be received within said first pipe member and a stepped portion disposed a predetermined distance from said first end portion, the stepped portion of said second pipe having a diameter greater than that of said first end portion; and a nut loosely and rotatably fitted around the circumference of said second pipe and having an internally threaded portion for mating engagement with the externally threaded portion of said first pipe member, said internally threaded portion having a first internally threaded portion and a second internally threaded portion, the first internally threaded portion being of a smaller diameter than the second internally threaded portion, said first and second internally threaded portions being synchronised in the axial direction, whereby said first and second pipe members are joined together by simultaneously engaging the external threads of the first and second externally threaded portions of the first pipe member with the internal threads of the first and second internally threaded portions respectively of the nut and rotating said nut over said end portion of said first pipe to draw the threads of the threaded end portion of the first pipe member into the threads of the nut. It is an advantage of the present invention that the pipe members can be joined together with fewer rotations of the nut member and still provide an appropriate amount of holding force to keep the pipes together. It is an additional advantage that the coupling includes a rotatable nut member having synchronised threads which allow the pipe member to remain fixed while the nut is rotated to couple the members The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a coupling structured in accord with the principles of the present invention, Figure 2 is an exploded view of the coupling of Figure 1, and Figure 3 is a cross-sectional view of the coupling of Figure 1 taken along line 3-3 thereof. Referring now to the drawings, Figure 1 is a perspective view of the fluid coupling assembly 10 of the present invention. The coupling 10 has particularly utility in fluid transport in automotive applications, such as air conditioning refrigerant lines, fuel lines, brake and power steering fluid lines and the like. The present invention works equally as well in other applications and the present invention is not meant to be solely limited to automotive applications. The coupling 10 includes a first pipe member 12 and a second pipe member 14 connected together by a joint assembly 16. The joint assembly 16 includes a male nut portion 18 engageable with a female nut portion 20. Referring to Figures 2 and 3, the first pipe member 12 includes an externally threaded end portion 22. This portion 22 includes a first externally threaded portion 24 and a second externally threaded portion 26. These threaded portions 24, 26 can be formed integrally as part of the pipe member 12 or, as shown, be formed on a male nut member 18 which has been secured to the pipe member 12. The threads formed into each of the externally threaded portions 24, 26 are identical in thread pitch. Also, the threaded portions are aligned to be axially synchronised, the importance of which will be described below. As shown in Figure 2, the threaded portion 24 extends further from the pipe member 12 than the threaded portion 26 and has a diameter less than that of the second threaded portion 26 to form a stepped configuration. This allows for easy alignment and insertion into the female nut member 20. The second pipe member 14 is a generally elongated tubular member having a first end 30 and a second portion 32. The first portion has a predetermined length defined by shoulder 34 and a predetermined diameter. The diameter of first portion 30 is chosen so that the first portion 30 is received within the first pipe member 12 for fluid connection. The second portion 32 of second pipe member 30 has a greater diameter that the first portion. This also defines a stepped configuration. A female nut 20, such as a swivel nut or sleeve nut, is slidably and rotatably disposed around the exterior surface of the second pipe member 32. The nut 20 is configured to matingly engage with male nut portion 18 such that a leak tight coupling is made when the portions are rotatably secured together. The nut 20 includes an internally threaded portion 40 which matingly engages the externally threaded portion of male nut 18. The internally threaded portion 40 of nut 20 includes a first internally threaded portion 42 and a second internally threaded portion 44. These internally threaded portions have identical thread pitch and are synchronised in the axial direction. Further, the first 42 and second 44 internally threaded portions are axially aligned. The first internally threaded portion extends a predetermined distance further in the nut than does the second internally threaded portion 44. To join the first and second pipe members together, the pipe members 12, 14 are brought together such that the first end of the second pipe 14 is placed in the opening of the first pipe 12. The female nut 20 is slid over the male nut 18 so that the threaded portions all simultaneously engage. Specifically, the female nut 20 is slid over male nut 18 such that the first external threads 24 matingly engage the first internal threads 42 while at the same time, the second external threads 26 engage with the second internal threads 44. The female nut 20 is rotated and all threads engage simultaneously. The male nut 18 is drawn into the female nut 20 by this rotation until the end of the male nut reaches the shoulder 34. By using a thread arrangement as described with a rotatable swivel nut, less rotation of the nut is required for an equal force to be achieved with a conventional nut arrangement. Additionally, the swivel nut allows for easy installation in many tight or hard to reach places since the nut is rotated about the pipe, and the pipe does not have to be rotated. To prevent fluid leaks, a sealing device, such as 0-ring 48 can be used at the shoulder 34 of the second pipe member 14. A circumferential upset may be formed in the second pipe member as well to prevent axially movement of the swivel nut beyond a predetermined maximum distance. Many other variations of the present invention will no doubt, occur to those skilled in the art. For example, the materials used in forming the pipe members or nut members can be steel, aluminium, or others. Furthermore, the number of threads formed in the nut members will depend on the amount of force required for a specific application.

Claims: A fluid coupling comprising: a first pipe member (12) having an externally threaded end portion (22), a second pipe member (14) having a first end portion (30) of predetermined length and diameter and configured to be received within said first pipe member (12) and a stepped portion (32) disposed a predetermined distance from said first end portion (30), the stepped portion (32) of said second pipe (14) having a diameter greater than that of said first end portion (30); and a nut (20) loosely and rotatably fitted around the circumference of said second pipe (14) and having an internally threaded portion (40) for mating engagement with the externally threaded portion (22) of said first pipe member (12), characterised by said threaded end portion (22) having a first externally threaded portion (24) of predetermined diameter extending a predetermined distance and a second externally threaded portion (26) having a predetermined diameter greater than the diameter of said first threaded portion (24) and extending axially adjacent thereto so as to form a stepped portion, the first threaded portion (24) extending further from the pipe member (12) than the second threaded portion (26); said internally threaded portion (40) having a first internally threaded portion (42) and a second internally threaded portion (44), the first internally threaded portion (42) being of a smaller diameter than the second internally threaded portion (44), said first and second internally threaded portions (42,44) being synchronised in the axial direction, whereby said first and second pipe members (12,14) are joined together by simultaneously engaging the external threads of the first and second externally threaded portions (24,26) of the first pipe member (12) with the internal threads of the first and second internally threaded portions (42,44) respectively of the nut (20) and rotating said nut over said end portion (22) of said first pipe (12) to draw the threads of the threaded end portion (22) of the first pipe member (12) into the threads of the nut (20). A fluid coupling as claimed in claim 1, wherein the first and second externally threaded portions (24,26) of said first pipe member (12) are synchronised in the axial direction. A fluid coupling as claimed in claim 1 or 2, wherein said externally threaded end portion (22) of said first pipe member (12) comprises a male nut (18) secured to said first pipe member (12). A fluid coupling as claimed in claim 1, 2 or 3, further including a circumferential upset (34) on said second pipe member (14), said upset being configured to prevent axial movement of the internally threaded nut (20) therepast, and seal means (48) disposed at said upset (34). A fluid coupling as claimed in claim 4, wherein said seal means is an 0-ring (48).

Inventors: NADER JR JOSEPH, SCHROEDER FRED GEORG, ZENG ZHONG PING, NADER JR., JOSEPH, SCHROEDER, FRED GEORG, ZENG, ZHONG PING
Applicants: FORD MOTOR CO, FORD MOTOR COMPANY
Application year: 1999
Main classification: F16L19
IPC codes: F16L19, F16L15