Abstract:
The invention relates to a swivel connection for a flexible dryer duct. The swivel connection is comprised of two sleeves, one of which can slide within the other. Each of the sleeves can be connected to a section of duct. The inner sleeve has an outwardly projecting flange that can engage an inwardly projecting flange on the outer sleeve, preventing the sleeves from being pulled apart, but allowing relative rotational movement between the sleeves.

Description:
This appln claims benefit of Prov. No. 60/137,811 filed Jun. 4, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to flexible, expandable, duct for use with household appliances, especially clothes dryers. The invention relates more particularly to a duct having one or more torque-relieving swivel connections having a simplified configuration to facilitate cost-effective construction and assembly. 
     2. Related Art 
     Flexible helical duct is widely used to direct the exhaust air of household appliances, such as clothes dryers. The flexible helical duct is typically made from a thin metal having a continuous helical ridge, separated by a continuous helical valley. The longitudinal expansion or contraction of the duct causes a rotation of the duct about its longitudinal axis. The rotation generates a torque that causes twisting and buckling of the duct. It is known to use a swivel connection at one or both ends of the duct to relieve the torque to reduce or eliminate the twisting and buckling of the duct. The known swivel connections employ a relatively complex rotary joint, which requires multiple manufacturing steps, thereby increasing the cost. Cost is an important consideration in the market success of flexible ducts. Because of the relatively large volumes and the fungible nature of competing products, a small cost advantage can provide a substantial competitive advantage. Therefore, there is always a strong desire and need to reduce cost. 
     Swivel connections are also found on non-longitudinally expanding duct, such as a plastic duct with a helical ridge. One such swivel connection comprises a collar that is threaded onto an end of the plastic duct and a sleeve mounted to the end of a different duct and which slidably receives and retains the collar. Other instances of prior teaching call for the threaded attachment of the end of the duct to the swivel connection. This requires complex manufacturing and assembly steps not needed with the present invention. 
     SUMMARY OF THE INVENTION 
     The invention relates to a swivel connection for connecting two ducts to each other, end-to-end, so that they are rotatable relative to each other. In one aspect of the invention, the swivel connection includes a pair of sleeves, one of which is slidable within the other. A first sleeve has a first end, a second end, and a flange spaced from the first end and extending outwardly from the sleeve. The second sleeve has a first end, a second end, and a shoulder spaced from the first end and extending inwardly from the sleeve. Both the flange and the shoulder extend a sufficient distance so that at least a portion of the flange and the shoulder abut each other upon slidable insertion of the first sleeve into the second sleeve. When thus inserted, the flange and the shoulder will prevent separation of the first and second sleeves from each other and an axial direction while permitting the first and second ducts to rotate relative to each other. 
     Preferably, the sleeves each have a circular cross section and the flange and shoulder will be annular and continuous. In one embodiment, the flange and shoulder are each located adjacent to the first end of the respective sleeve. 
     The flange and shoulder can each be formed of a rolled edge, a lip, or a simple protruding projection. Preferably, the sleeves are formed of thin metal, but they also can be formed of integrally molded plastic. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described with reference to the drawings wherein: 
     FIG. 1 is a cross-sectional view of a first embodiment of a duct with a swivel connection in accordance with the present invention; 
     FIG. 2 is an enlarged cross section of a portion of the swivel connection in the duct of FIG. 1; 
     FIG. 3 is a cross-sectional view of a second embodiment of a duct with a swivel connection in accordance with the present invention; 
     FIG. 4 is an enlarged cross section of a portion of the swivel connection in the duct of FIG. 3; 
     FIG. 5 is a cross-sectional view of a third embodiment of a duct with a swivel connection in accordance with the present invention; and 
     FIG. 6 is an enlarged cross section of a portion of the swivel connection in the duct of FIG.  5 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings and to FIGS. 1 and 2 in particular, a first embodiment of a dryer duct assembly is shown and comprises a first portion of thinwalled, metal, helical duct  10  and a second portion of thin-walled, metal, helical duct  12 , connected by a swivel connection assembly  16 . Said duct is formed by conventional methods whereby the thin wall is provided with helical convolutions producing a plurality of alternating ridges  20  and valleys  22  when viewed in cross section as in FIG.  1 . In reality, a single continuous helical ridge and a single contiguous helical valley define the shape of the duct. The apexes of the ridges  20  and valleys  22  act as integral joints providing for the expansion and contraction of the duct under corresponding tensile and compressive loads, respectively. 
     The swivel connection assembly  16  comprises a female sleeve  30  and a male sleeve  40 , each having an end fixedly connected to the corresponding helical duct  10 ,  12 . Toward the other end of each sleeve is a projection formed by rolled flanges  32 ,  42 , respectively, which cooperate to rotatably connect the sleeves  30 ,  40  and, thus, the ducts  10 ,  12 . Each projection is in the form of an inwardly projecting shoulder or an outwardly projecting flange. 
     Each sleeve of the first embodiment is shown to be of a cylindrical shape, constructed of metal with a wall thickness corresponding with that of the helical metal duct and terminating in its rolled flange. The female sleeve  30  is shown adjacent to and overlapping the first portion of the duct  10 . The inner diameter  31  of the female sleeve  30  is preferably larger than the outer diameter of the duct  14 , which is equal to the diameter of the ridges  20 , to permit the duct  14  to be received within the female sleeve  30 . Correspondingly, the male sleeve  40  is shown adjacent and interior to the second duct portion  12 . The outer diameter  41  of the male sleeve  40  is somewhat smaller than the inner diameter of the duct  16 , which corresponds to the diameter of the valleys  22 , to permit the male sleeve  40  to be received within the duct  12 . 
     The female sleeve flange  32  is rolled inwardly and the male sleeve flange  42  is rolled outwardly. Preferably, the inner diameter of the female sleeve  30  is slightly larger than the diameter of the male sleeve flange  42 . The outer diameter of the male sleeve  40  is smaller than the diameter of the female flange  32 . The assembly of these two pieces is accomplished by sliding an unrolled or plain end  44  of the male sleeve  40  through an unrolled or plain end  34  of the female sleeve  30  until the rolled flanges contact one another. Thus, the outwardly rolled flange  42  is longitudinally retained in position by abutting contact with the inwardly rolled flange  32 . Thus, the sleeves are fittingly retained in a slideable axial relationship that permits rotary movement relative to one another. 
     To assemble the duct assembly, the male sleeve  40  is inserted into the unrolled end of the female sleeve  30  until at least a portion of the unrolled end of the male sleeve  40  extends beyond the flange  32  of the female sleeve. The unrolled end of both sleeves is then affixed to the corresponding duct. Preferably, the sleeves are attached to the duct portions by fasteners  50 ,  52 , that leave as smooth a surface as possible on the inside of the duct in order to minimize places for lint to catch. Such fasteners include self-piercing rivets or clinch locks. Of course, other fasteners such as selftapping screws or “pop” rivets can be used with less effect, as well as other methods such as spot welds or the like. Attachment of the female sleeve  30  to the first duct portion  10  is accomplished by preferably screwing a plurality of self-tapping screws through the female sleeve  30  and into an adjacent ridge  20  or ridges of the duct. Similarly for the male sleeve  40 , except that the fastener penetrates the valley  22  of the second duct portion  12  before attaching to the sleeve  40 . For the application of aluminum rivets or screws that are not self-tapping, holes must first be drilled or punched through the sleeve and duct to receive the fastener. 
     Although one of the sleeves is illustrated having a diameter sized to be received within a duct and the other sleeve is illustrated as being sized to receive a duct, it is within the scope of the invention for each sleeve to be sized to be received within a duct or to receive a duct. Depending on the selected sleeve diameter, it may be necessary to shape the duct or alter the collars to obtain an abutting relationship between the collars. 
     A second embodiment of a duct assembly is shown in FIGS. 3-4 and is comprised of thin-walled, metal, helical duct as previously described in combination with a new swivel connection  58 . Since the flexible duct and fasteners are common between the first and second embodiments, they are not shown or described in detail. The swivel connection assembly  58  shown in FIG. 3 is comprised of a female sleeve  60  and a male sleeve  70 . Both sleeves shown are to be of a cylindrical shape, constructed of injection molded plastic and terminating in a protruding projection. The female sleeve  60  has a shoulder or projection  62  that protrudes inwardly and an opposing plain end  64 . The male sleeve  70  has a flange or projection  72  that is protrudes outwardly and an opposing plain end  74 . Preferably, the inner diameter of the female sleeve  60  is slightly larger than the diameter of the projection  72  of the male sleeve  70 . Likewise, the outer diameter of the male sleeve  70  should have a diameter corresponding to the smaller diameter of the projection  62  of the female sleeve  60 . 
     The assembly of these two sleeves is generally the same as for the first embodiment. The plain end  74  of the male sleeve  70  extends through the plain end  64  of the female sleeve  60  until the protruding projections contact one another. Thus, the outwardly protruding projection  72  of the male sleeve  70  is retained in position by the interior diameter  61  and the inwardly protruding projection  62  of the female sleeve  60 . The female sleeve is restricted in movement by the end of the second duct portion  12  when said duct is attached to the male sleeve as will be depicted shortly. These two sleeves are thereby fittingly retained in a slideable axial relationship that permits rotary movement relative to one another. 
     The female sleeve  60  is shown adjacent to and overlapping the first portion of the duct  10 . The inner diameter  61  of the female sleeve  60  is somewhat larger than the outer diameter of the duct  14 , which is equal to the diameter of the ridges  20 . Correspondingly, the male sleeve  70  is shown adjacent and interior to the second portion of the duct  12 . The outer diameter  71  of the male sleeve  70  is somewhat smaller than the inner diameter of the duct  16 , which corresponds to the diameter of the valleys  22 . 
     The sleeves are attached to the duct portions by fasteners  50  and  52 . Attachment of the female sleeve  60  to the first duct portion  10  is accomplished by preferably screwing a plurality of self-tapping screws through the female sleeve  60  and into an adjacent ridge  20  or ridges of the duct. Similarly for the male sleeve  70 , except that the fastener penetrates the valley  22  of the second duct portion  12  before attaching to the sleeve  70 . For the application of aluminum rivets or screws that are not self-tapping, holes must first be drilled or punched through the sleeve and duct to receive the fastener. 
     A third embodiment of the dryer duct assembly is shown in FIGS. 5 and 6, comprising a flexible helical duct in combination with a new swivel connection. Like numerals will be used to describe like parts of the various embodiments. 
     The swivel connection assembly  78  shown in FIGS. 5 and 6 is comprised of a female sleeve  80  and a male sleeve  90 . Both sleeves shown are to be of a cylindrical shape, constructed of thin-walled metal or injection-molded plastic and terminating in a lip that extends at an angle acute to a radius of the sleeves. However, it is within the scope of the invention for the lip to extend radially from the sleeve. The female sleeve  80  has a shoulder or lip  82  that is directed inwardly and an opposing plain end  84 . The male sleeve  90  has a flange or lip  92  that is directed outwardly and an opposing plain end  94 . Preferably, the inner diameter of the female sleeve  80  is slightly larger than the diameter of the outwardly directed lip  92  of the male sleeve  90 . Likewise, the outer diameter of the male sleeve  90  should have a diameter corresponding to the smaller diameter of the inwardly directed lip  82  of the female sleeve  80 . 
     The assembly of the sleeves is accomplished by sliding the plain end  94  of the male sleeve  90  through the plain end  84  of the female sleeve  80  until the complimentary lips  82 , 92  contact one another. Thus, the outwardly directed lip  92  of the male sleeve  90  is retained in position by the interior diameter  81  and the inwardly directed lip  82  of the female sleeve  80 . The female sleeve is restricted in movement by the end of the second duct portion  12  when said duct is attached to the male sleeve as will be depicted presently. The sleeves are thereby fittingly retained in a slideable axial relationship that permits rotary movement relative to one another. 
     The female sleeve  80  is shown adjacent to and overlapping the first portion of the duct  10 . The inner diameter  81  of the female sleeve  80  is somewhat larger than the outer diameter of the duct  14 , which is equal to the diameter of the ridges  20 . Correspondingly, the male sleeve  90  is shown adjacent and interior to the second portion of the duct  12 . The outer diameter  91  of the male sleeve  90  is somewhat smaller than the inner diameter of the duct  16 , which corresponds to the diameter of the valleys  22 . 
     The sleeves are attached to the duct portions by fastening means  50  and  52 , as disclosed previously. 
     Any features in the foregoing embodiments can be selectively incorporated into other embodiments. For example, female sleeve  30  can accommodate male sleeve  70  or  90  as discussed relative to the inner and outer diameters of each sleeve. All possible derivations known to those having ordinary skill in the art with the present disclosure before them are likewise contemplated for use. For example, non-metal helical duct such as wire reinforced vinyl, will also have a tendency to twist as it is expanded, although perhaps to a lesser degree. Sleeves having shapes other than a right circular cylinder can be used in lieu of the embodiments described. Nevertheless, it is within the scope of the invention to incorporate the swivel embodiments described into any segmented duct where a swivel connection is desired. 
     Additionally, it is envisioned that a plurality of swivel connections can be used to connect multiple duct segments. The swivel connections can be of the same type or can include any combination of the various embodiments described above. Moreover, these connections may be located at a standard distance, whereas different lengths of swivel duct would be comprised of varying numbers of standard length sections of duct with a swivel connection between each section. The swivel connections can also be used to connect various connectors, such as elbows, to other connectors or to other ducts. 
     While particular embodiments of the invention have been shown, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. Reasonable variation and modifications are possible within the scope of the foregoing invention disclosure, without departing from the spirit of the invention.