Abstract:
The present invention comprises a breather system and a method of using the system. The assembly has a breather tube, a baffle system at least partially located within the breather tube and a drain back tube connected to the breather tube. The baffle system has a plurality of baffles designed to prevent lubricant from escaping a housing while still allowing air to pass into and out of the housing.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a breather system and a method of using the breather system. More particularly, the present invention relates to a breather system for a housing, for example a vehicle drive axle housing and a method of using the breather system with the housing. 
     BACKGROUND OF THE INVENTION 
     Breather assemblies for axle housings, transmission housings and other housings having rotatable elements therein and/or non-rotatable elements therein are well known for venting the interior of the housing to the atmosphere. The operation of the rotatable elements within these housings typically generates a certain amount of heat. The lubricant within the housings, used to facilitate the rotation of the rotatable elements, receives this heat. The heat increases the vapor pressure of the lubricant and the air, or gas, within the housing. If this pressure is not expelled from the housing, the lubricant will be undesirably forced through whatever sealing means are in place. 
     Various breather assemblies for the housings described above have been patented. For example, U.S. Pat. No. 2,880,744 provides for a housing vent that includes a tubular vent body with a separate baffle disk mounted within the vent body. 
     U.S. Pat. No. 3,145,582 teaches a breather assembly having a single pair of baffle plates therein. The baffle plates are designed to collect any lubricant spray that may enter the breather and return to the case. The plates are also designed to also allow gas to escape from the case. The baffle plates have gas openings that are not aligned with one another to reduce the likelihood that fluid will go through both and escape through the assembly. The plates are described and depicted as located within a stand pipe of the assembly. 
     U.S. Pat. No. 4,794,942 teaches an air breather plug assembly having a cylindrical plug body and a cup-shaped baffle plate fixedly coupled within an inner end portion of the plug body. The baffle plate has a pair of radially spaced semi-circular slots formed therein. The slots are designed to permit only a small amount of lubricant into the plug body. A resilient seal member, located above the baffle plate, has a slit that opens only if the pressure within the assembly exceeds a pre-determined amount. The resiliency of the seal member generally keeps the slit closed, thus maintaining the small amount of lubricant located within the plug body. 
     The above-described breather assemblies suffer from several disadvantages. First, the prior art breather assemblies have to be located above the lubricant level in the housing. Second, these breather assemblies have to be located at specific angles with respect to the housings to function properly. Third, despite their designs, the breather assemblies are known to allow lubricant, sometimes a significant quantity, to escape from the housing. Fourth, the prior art designs lack means to prevent a lubricant seal from forming against the base of the breather assembly thus blocking air from entering into and escaping from the housing. In light of the disadvantages of the prior art, a breather system that can be installed anywhere on a housing, at any angle, that significantly reduces, or prevents, lubricant from escaping from the housing, yet allows air into and out of the housing, is needed. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward a breather system having a breather tube, a baffle system and a drain back tube. The baffle system is located substantially within one end of the hollow interior of the breather tube. The baffle system has a first end partially closed by a first baffle, a second end partially closed by a second baffle and a third baffle positioned between the first baffle and the second baffle. The drain back tube has a plurality of legs and it is connected to the breather tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description when considered in the light of the accompanying drawings in which: 
         FIG. 1  is an exploded view of a preferred embodiment of the breather system of the present invention; 
         FIG. 2  is a perspective view of a preferred embodiment of an interior of the baffle system of the present invention; 
         FIG. 3  is a perspective view of a preferred embodiment of the baffle system of the present invention; 
         FIG. 4  is a perspective view of a preferred embodiment of the drain back tube of the present invention; and 
         FIG. 5  is a side view of the present invention depicting a preferred embodiment of the assembled breather system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions, directions or other physical characteristics relating to the embodiments disclosed are not to be considered as limiting, unless the claims expressly state otherwise. 
     Referring now to  FIG. 1 , a preferred embodiment of the breather system  10 , comprising a breather tube  12 , a baffle system  14  and a drain back tube  16 , of the present invention is depicted. The breather tube  12  has a body portion  18  having an upper portion  20  and a lower portion  22 . The upper portion  20  has a structure  24 , such as a bolt head, having a plurality of flats  26 , such as wrench flats or socket flats. The lower portion  22  has a set of threads  28  integrally formed therewith. The lower portion  22  also has a reduced outside diameter section  30  that terminates in a bottom edge  32  having a substantially circular opening  34 . Preferably, the reduced outside diameter section  30  has a circumferential groove  36 . 
     The body portion  18  has a substantially hollow interior portion  38 . Preferably, the interior portion  38  is generally cylindrical in shape and extends from the circular opening  34  to approximately the bolt head  24 . 
     Between the set of threads  28  and the bolt head  24 , a tube connector  40  preferably extends in a substantially horizontal direction with respect to the body portion  18 . The tube connector  40  is generally cylindrical and may be integrally formed at a first end  42  with the body portion  18  or separately formed therefrom and joined to the body portion  18 . Preferably, the tube connector  40  has a hollow interior  44  in fluid communication with the hollow interior  38  of the body portion  18 . 
     The tube connector  40  preferably also has a second end  46 . The second end  46  terminates in a generally circular opening  48 . A fitting  50  is preferably located on an exterior surface  52  of the tube connector  40  adjacent the second end  46 . The fitting  50  may be a set of threads, a series of alternating ridges and grooves and/or one or more barbs. The fitting  50  accepts a tubular hose (not shown), which is well known to those skilled in the art. 
     The breather tube  12  may be metallic, such as, for example, steel or brass; however, it is well within the scope of the present invention to construct the breather tube  12  from plastic materials and/or elastomeric materials. The breather tube  12  may also be constructed of any combination of the above-mentioned materials. For example, the upper portion  20  and some of the lower portion  22  of the breather tube  12  is preferably constructed from brass and the reduced diameter section  30  is injection molded onto the lower portion  22 . 
       FIG. 1  also depicts a preferred embodiment of the baffle system  14  of the present invention. Preferably, the baffle system is constructed of plastic. By way of example only, the plastic may be such as an acrylonitrile-butadiene-styrene copolymer (ABS). Other materials such as rubber, synthetic rubber, nylon or similar materials are also within the scope of the present invention. 
     The baffle system  14  is preferably substantially tubular in overall shape; however, the baffle system  14  is not limited to merely tubular shapes. The baffle system  14  may be any shape that is complementary to the hollow interior portion  38  of the lower portion  22  of the body portion  18 . Preferably, the baffle system  14  has an interior  51  that is at least partially hollow. 
     In a preferred embodiment, the baffle system  14  has a first portion  54  and a second portion  56 , as shown in  FIG. 2 . Preferably, the first portion  54  comprises half of the tubular shape of the baffle system  14  and the second portion  56  comprises the other half of the tubular shape, however, the first portion  54  and the second portion  56  may comprise any percentage of the tubular shape. 
     The first portion  54  and the second portion  56  are preferably joined by at least one hinge  58  and more preferably the portions  54 ,  56  are joined by two hinges  58 . The hinges  58  are integrally formed with the first portion  54  and the second portion  56 , although the present invention functions equally well without the hinges  58 . Preferably, the hinges  58  are formed of a flexible material. 
     Preferably, the baffle system  14  has a first end  60  and a second end  62 , as best seen in  FIGS. 1 and 3 . The first end  60  has a circumferential radially extending edge  64 . In the preferred embodiment, the radially extending edge  64  is located at the terminus  66  of the first end  60 . The radially extending edge  64 , however, may be located anywhere on the first end  60  of the baffle system  14 . 
     The first end  60  of the baffle system  14  also has an opening  68  therein. In the depicted preferred embodiment, the opening  68  is semi-circular. Those skilled in the art will appreciate, however, that the opening  68  can be of any shape or design and it is not limited to being semi-circular in shape. The remaining portion of the first end  60  is closed by a first baffle  70 . 
     The first baffle  70  may be a solid plate or wall designed to deflect, check, regulate and/or limit the flow of lubricant from a housing, described in more detail below. The first baffle  70  may also be a porous, or mesh, plate or wall also designed to deflect, check, regulate and/or limit the flow of lubricant from the housing. The above description and function of the first baffle  70  applies to a second baffle  72  and a third baffle  74  which are described below. Those skilled in the art will appreciate that one or more of the baffles  70 ,  72 ,  74  may be solid or one or more of the baffles  70 ,  72 , or  74  may be porous, all in the same baffle system  14 . 
     Preferably, the first baffle  70 , the second baffle  72  and the third baffle  74  are located in the baffle system  14  substantially orthogonal with a vertical axis  76  of the baffle system  14 , as seen in  FIGS. 1 and 3 . The present invention, however, is not limited to locating the baffles  70 ,  72 ,  74  in strictly an orthogonal orientation. Instead, one or more of the baffles  70 ,  72 ,  74  may be located anywhere between 45 degrees to 135 degrees with respect to the vertical axis  76  of the baffle system  14 . 
     The second end  62  of the baffle system  14  has an opening  78  therein, as shown in  FIGS. 1 and 3 . Preferably, the opening  78  is semi-circular in shape, however, the opening  78  can be of any shape or design and it is not limited to being semi-circular in shape. The remaining portion of the second end  62  is closed by the second baffle  72 . 
       FIG. 1  depicts the preferred embodiment of the present invention where the first baffle  70  and the second baffle  72  are substantially axially aligned with, but axially offset from, one another. Preferably, the first baffle  70  and the second baffle  72  are substantially axially aligned with one another, however, it is within the scope of the present invention for the first and second baffles  70 ,  72  to have deviations in their alignment. 
       FIGS. 1 and 2  depict a third baffle  74  in the baffle system  14  located between the first baffle  70  and the second baffle  72 . Preferably, the third baffle  74  is located substantially equidistant from the first baffle  70  and the second baffle  72 , however, it is well within the scope of the present invention to locate the third baffle  74  anywhere between the first baffle  70  and the second baffle  72 . 
     In the preferred embodiment, the third baffle  74  defines a substantially semi-circular opening  80  with the tubular wall  82  of the baffle system  14 , as shown in  FIG. 1 . The opening  80  defined by the third baffle  74  may be any shape or design and it is not limited to only a semi-circular shape. 
     Preferably, the third baffle  74  is positioned within the baffle system  14  in a staggered, or alternating, relationship with respect to at least one other baffle  70  or  72 , as best seen in  FIG. 1 . In a most preferred embodiment, the third baffle  74  is axially staggered with both the first baffle  70  and the second baffle  72 . In this staggered orientation, the third baffle  74  may or may not at least partially axially overlap the first  70  and/or the second baffle  72 . It is preferred that the third baffle  74  be, at least partially, in an axially overlapping relationship with the first opening  68  and the second opening  78 . 
     Regardless of the orientation of the first baffle  70 , the second baffle  72  or the third baffle  74  with respect to one another, it is preferred that the baffles  70 ,  72 ,  74  are positioned so that a continuous air passageway  84 , as shown in  FIG. 1 , is present through the baffle system  14 . 
     Referring now to  FIGS. 1 and 4 , a preferred embodiment of the drain back tube  16  of the present invention is depicted. The drain back tube  16  is substantially tubular in shape and has a hollow interior portion  86 . Preferably, the drain back tube  16  has an upper portion  88  and a lower portion  90 . Preferably, the upper portion  88  has a slightly larger inside diameter  92  as compared to the reduced outside diameter section  30  of the breather tube  12 . 
     An inside surface  94  of the upper portion  88  preferably has a circumferential lip  96  that has a complementary shape to the circumferential groove  36  of the reduced diameter section  30  of the breather tube  12 . 
     The lower portion  90  of the drain back tube  16  has a plurality of legs  98 . Preferably, the legs  98  taper away from the upper portion  88 , however, those skilled in the art will appreciate that they may be any shape. As shown in  FIGS. 1 and 4 , the lower portion  90  preferably has four tapered legs  98 . The present invention, however, is not limited to four legs  98  as any number of legs  98 , greater or fewer than four, may be used without departing from the scope of the present invention. 
     The preferred embodiment also has one of at least two types of recesses extending upwardly into the drain back tube  16  between each of the legs  98 , as best seen in  FIG. 1 . A first type of recess  99 A extends almost to the upper portion  88 . A second type of recess  99 B does not extend as far upwardly into the drain back tube  16  as the first type of recess  99 A. Although the present invention describes and depicts two types of recesses  99 A,  99 B, it is within the scope of the present invention to have recesses having multiple depths and shapes and which are located in any order between the legs  98 . 
     A preferred method of using the above-described invention includes locating the baffle system  14  into the lower portion  22  of the breather tube  12 . Preferably, before this step, the first portion  54  and second portion  56  of the baffle system  14 , as shown in  FIG. 2 , are brought together. The first portion  54  and the second portion  56  are folded so that they are adjacent one another by virtue of the hinge  58 , or hinges, as the case may be. 
     Those skilled in the art will appreciate that the baffle system  14 , including the hinge  58  and the baffles  70 ,  72 ,  74 , can be molded or cast as a single piece, or as two joined pieces as shown in  FIG. 2 . By molding or casting the baffle system  14 , the first portion  54  can have integrally formed therewith any number of baffles  70 ,  72 , or  74 , as can the second portion  56 . The present invention, however, is in no way limited to only forming the baffle system  14  by molding or casting. 
     The baffle system  14  is then inserted into the breather tube  12  until the radially extending edge  64  on the first end  60  of the baffle system  14  engages the bottom edge  32  of the lower portion  22  of the breather tube  12 , as shown in  FIG. 5 . The drain back tube  16  is attached to the breather tube  12  by locating the circumferential lip  96  of the drain back tube  16  into the circumferential groove  36  in the breather tube  12 . Preferably, the drain back tube  16  has an interior ledge  100  that abuts the radially extending edge  64  of the baffle system  14 . Based upon this description and  FIG. 5 , it can be understood that when assembled the drain back tube  16  overlaps the radially extending edge  64  of the baffle system  14  and reduced diameter section  30  of the breather tube  12 . 
     Those skilled in the art will appreciate that the drain back tube  16  can be a separately formed, individual piece that is manually or automatically secured to the breather tube  12 . In the preferred embodiment, however, the drain back tube  16  is injection molded about the lower portion  22  of the breather tube  12 . 
     The drain back tube  16  may be constructed of plastic, rubber, synthetic rubber or similar products. In a preferred embodiment, the drain back tube  16  is constructed of nylon. By way of example only, the drain back tube  16  may be constructed of BASF Ultramid nylon. 
     The breather system  10 , including the breather tube  12 , the baffle system  14  and the drain back tube  16  are then installed in a housing  102 , as shown in  FIG. 5 . The breather system  10  may be located anywhere on the housing  102 , and at any angle with respect to the housing  102 . In the preferred embodiment depicted in  FIG. 5 , the breather system  10  is inserted into the housing  102  in a substantially perpendicular position. 
     An aperture  104  extends completely through the housing  102 . The aperture  104  includes a complementary set of threads  106  to those on the breather tube  12 . The breather system  10  is inserted into the aperture  104  in the housing  102  and rotated so that the two sets of threads  28 ,  106  engage with one another. The breather system  10  may be rotated by hand, with a manual tool, such as a wrench, or a powered tool, such as an air driven wrench. Preferably, the breather system  10  is located into the housing  102  until the two sets of threads  28 ,  106  are fully engaged and/or until a fluid tight seal is formed between the breather system  10  and the housing  102 . 
     It can now be appreciated that the air within an interior portion  108  of the housing  102  is in communication with the atmosphere outside of the housing  102  by virtue of the breather system  10 . Air within the interior portion  108  can flow past the first baffle  70 , past the second baffle  72  and past the third baffle  74  of the baffle system  14  into the breather tube  12 . The air may then continue through the interior portion  38  of the breather tube  12 . The air will then move from the interior portion  38  of the breather tube  12  to the interior  44  of the tube connector  40  where it eventually reaches the atmosphere. Air moving into the housing  102  from the atmosphere simply follows the above-described path in reverse. 
     Although air is allowed to freely move from the interior portion  108  of the housing  102  to the atmosphere, fluid within the housing  102 , such as a lubricant  110 ,is prevented from doing so by virtue of the baffle system  14  and the drain back tube  16 . The tapered plurality of legs  98  of the drain back tube  16  prevent a significant quantity, if not all, of the lubricant  110  that is being splashed or thrown against them from entering into the upper portion  88  of the drain back tube  16 . The legs  98  are also a highly variable surface that makes it very difficult for the lubricant  110  to form an airtight seal against. Additionally, the variability of the recesses  99 A,  99 B between the legs  98  prevents, or reduces the likelihood of, the lubricant  110  forming an airtight seal in the drain back tube  16 . Those skilled in the art can appreciate that the formation of a lubricant seal in the breather system  10  can create a vacuum within the breather system  10  thus reducing the effectiveness of the breather system  10 , if not disabling it. 
     All of, or the majority of, any lubricant  110  which is splashed or thrown against the breather system  10 , or which otherwise comes in contact with the breather system  10 , is also prevented escaping as it is blocked by the first baffle  70 . In the unlikely event that lubricant  110  escapes past the first baffle  70 , the third baffle  74 , located in the axially staggered location described above, blocks the lubricant  110  from moving further into the baffle system  14 . Should the lubricant  110  move past the third baffle  74 , the second baffle  72 , staggered axially from the third baffle  74  would prevent the lubricant  110  from advancing further. 
     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiments. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.