Abstract:
A barrier membrane assembly for sealing a constant velocity joint assembly includes at least one selectively expandable and contractible barrier membrane body. The barrier membrane body has no openings therethrough and may selectively expand and contract in response to operational pressures acting against the barrier membrane body.

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to a barrier assembly, and more particularly, to a selectively expandable and contractible barrier that is permitted to expand in response to pressures within a constant velocity joint assembly. 
     BACKGROUND 
     Constant velocity joints are common components in automotive vehicles. Typically, constant velocity joints are employed where transmission of a constant velocity rotary motion is desired or required. Common types of constant velocity joints include plunging tripods, fixed tripods, plunging ball joints and fixed ball joints. These types of joints currently are used in front wheel drive vehicles or rear wheel drive vehicles, and on the propeller shafts found in rear wheel drive, all wheel drive and four wheel drive vehicles. Constant velocity joints are generally grease lubricated for life and sealed with sealing boots when used on drive shafts. Thus, constant velocity joints are sealed in order to retain grease inside the joint while keeping contaminants and foreign matter, such as dirt and water, out of the joint. To achieve this protection, the constant velocity joint is usually enclosed at the open end of the outer race by a sealing boot made of a rubber, thermoplastic, or silicone material. The opposite end of the outer race generally is enclosed by a dome or cap, known as a grease cap. A monoblock or integral stem and race design style does not use a grease cap, but is sealed by the internal geometry of the outer race. Sealing and protection of the constant velocity joint is necessary because contamination of the inner chamber may cause internal damage and destruction of the joint. Furthermore, once the inner chamber of the joint is lubricated, it is lubricated for life. 
     During operation, the constant velocity joint creates internal pressures in the inner chamber of the joint. The internal pressure is the result of increases in internal or external temperature. These pressures must be vented to the outer atmosphere in order to prevent pressure build-up. If the pressure build-up is allowed to reach a critical state, the boot, which protects the joint from contaminants and water, may deform, crack, deteriorate, or blow out, thus diminishing the life of the boot and losing its ability to properly seal the joint. A constant velocity joint is usually vented by placing a small hole generally in the center of the grease cap or at least one hole around the outer periphery of the boot neck. These methods of venting the pressure build up are sometimes not adequate because if the constant velocity joint is in a static state and not rotating the lubricating grease may settle in the vent hole and block or hinder its venting function and/or evacuate lubricant from the joint. This type of vent may also allow infiltration of contaminants. Once the internal pressure builds up, the joint may fail due to a ruptured boot or other catastrophe. Furthermore, the constant velocity joint, after running for long periods of time, may create very high temperatures along with high pressures which are vented through the current vent holes. However, if the constant velocity joint is submerged or saturated in water or other contaminants, the water will, via a rapid temperature change cause a vacuum, within the joint chamber and draw water into the constant velocity joint, thus contaminating the grease lubricant and reducing the life of the constant velocity joint. 
     Therefore, there is a need for a constant velocity joint that will prevent the build up of internal pressure while eliminating the possible ingress of contaminants from entering the constant velocity joint. 
     SUMMARY 
     A barrier membrane assembly for sealing a constant velocity joint assembly is disclosed. The barrier membrane includes at least one selectively expandable and contractible barrier membrane body. The barrier membrane body has no openings therethrough and may selectively expand and contract in response to operational pressures acting against the barrier membrane body. 
     In one embodiment, the barrier membrane is disposed within a constant velocity joint. In another embodiment, the constant velocity joint includes two barrier membranes, such as illustrated, for example, in  FIGS. 9-14 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention will become apparent from the subsequent description and appended claims, taken in conjunction with the accompanying drawings. 
         FIG. 1  is a cross-sectional view of an embodiment of a constant velocity joint assembly employing a barrier membrane. 
         FIG. 2  is a cross-sectional view of a constant velocity joint assembly of  FIG. 1 , illustrating an alternative method of attaching the barrier membrane to the constant velocity joint. 
         FIG. 3  is a cross-sectional view of a constant velocity joint employing a second barrier membrane. 
         FIG. 4  is a cross-sectional view of a constant velocity joint employing an alternative embodiment of the second barrier membrane. 
         FIG. 5  is a cross-sectional view of a constant velocity joint employing a second alternative embodiment of the second barrier membrane. 
         FIG. 6  is a detailed view of the barrier membrane of  FIG. 1  before operation of the constant velocity joint. 
         FIG. 7  is a detailed view of the barrier membrane of  FIG. 6  at the start of operation of constant velocity joint before the temperature of the joint has reached normal operating level. 
         FIG. 8  is a detailed view of the barrier membrane of  FIG. 6  under hard working conditions when the constant velocity joint is spinning at speed and the joint temperature is high. 
         FIG. 9  is a cross-sectional view of a constant velocity joint assembly employing the barrier membranes illustrated in  FIGS. 1 and 3 . 
         FIG. 10  is a cross-sectional view of a constant velocity joint assembly employing the barrier membranes illustrated in  FIGS. 1 and 4 . 
         FIG. 11  is a cross-sectional view of a constant velocity joint assembly employing the barrier membranes illustrated in  FIGS. 1 and 5 . 
         FIG. 12  is a cross-sectional view of a constant velocity joint assembly employing the barrier membranes illustrated in  FIGS. 2 and 3 . 
         FIG. 13  is a cross-sectional view of a constant velocity joint assembly employing the barrier membranes illustrated in  FIGS. 2 and 4 . 
         FIG. 14  is a cross-sectional view of a constant velocity joint assembly employing the barrier membranes illustrated in  FIGS. 2 and 5 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, an embodiment of a constant velocity joint  10  according to the present invention is shown. It should be noted that any type of constant velocity joint such as a plunging tripod, a fixed tripod, etc. may be used in connection with the present invention. For the convenience of the reader, like elements have been give the same element numbers through the drawings. 
     Referring to  FIG. 1 , the constant velocity joint  10  includes an outer race  12  with an inner race  14  located within the circumference of outer race  12 . Inner race  14  is operably connected to a shaft  16 . At least one rolling element  18  is in contact with both an inner surface of the outer race  12  and an outer surface of the inner race  14 . The rolling element  18  is held in place by a cage  20 . An optional end cap  22  is located on one end of the outer race  12 . While the illustrative embodiment includes end cap  22 , it is understood that end cap  22  is not required and may be eliminated in its entirety for some applications. 
     A selectively expandable and contractible first barrier membrane  50  is mounted to outer race  12 . In one embodiment, first barrier membrane  50  includes a distal outer edge  52  that extends radially outwardly from barrier membrane  50 . At least a portion of distal outer edge  52  is disposed within groove  28 . For example, as shown in  FIG. 1 , a portion of distal outer edge  52  is received within second leg  32  of groove  28  with a portion of distal end  34  of end cap  22 . 
     In another embodiment, as shown in  FIG. 2 , barrier membrane  50  terminates in an outer edge  58 . Outer edge  58  is fixedly attached to inner surface  56  of end cap  22  by bonding or other suitable methods. In this embodiment, a sealing member  36 , such as an o-ring or the like, may be inserted within second leg  32  of groove  28  to assist in retaining end cap  22  within groove  28 . 
     A boot cover  40  is positioned on an opposite end of the outer race  12  from end cap  22 . One end of boot cover  40  is secured to outer race  12  by bonding, crimping or other suitable attachment techniques. In one embodiment, boot cover  40  includes a channel  42  on a periphery thereof. Within the channel  42 , one end  44  of a boot  46  is disposed. In one embodiment, the boot  46  may be made of a neoprene material, however, it should be noted that any other type of soft rubber like or composite material may also be used. The opposite end of the boot  46  is secured to the shaft  16  by a clamp  48  or other available securing mechanism. 
     A selectively expandable and contractible first barrier membrane  50  is mounted to outer race  12 . In one embodiment, first barrier membrane  50  includes a distal outer edge  52  that extends radially outwardly from barrier membrane  50 . At least a portion of distal outer edge  52  is disposed within groove  28 . For example, as shown in  FIG. 1 , a portion of distal outer edge  52  is received within second leg  32  of groove  30  with a portion of distal end  34  of end cap  22 . 
     Another embodiment of second barrier member  60 ′ is shown in  FIG. 4 . Second barrier member  60 ′ is defined by a first end  62 ′ and a second engagement portion  68 . The first end  62 ′ is bonded or otherwise attached to boot cover  40 . The second engagement portion  68  extends along a portion of shaft  16 . Second engagement portion  68  may be frictionally retained on shaft  16  by a clamp  48  or other suitable mechamsm. 
     In one embodiment, barrier membrane  50  extends substantially over the entire first end of constant velocity joint  10 . An expansion space  54  is defined between an inner surface  56  of end cap  22  and barrier membrane  50 . Barrier membrane  50  is designed to be at least substantially abrasion and wear resistant, as well as substantially elastic and impermeable. The barrier membrane  50  may be constructed of a natural or synthetic elastic material, such as neoprene, butylenes, styrene, silicone or other suitable material. Operation and function of barrier membrane  50  will be explained in further detail below. 
     In another embodiment, a second barrier membrane  60  is provided. Second barrier membrane  60  may be mounted on the second end of the constant velocity joint  10  assembly between the cage  20  and the boot  46 . The second membrane may be of identical composition and properties as defined for barrier  48 . An example of such an embodiment is shown in  FIG. 3 . In such an embodiment, barrier membrane  60  is disposed between boot cover  40  and shaft  16 . A first end  62  is fixedly attached to boot cover  40 , by bonding or other suitable methods. A second end  64  of membrane  60  is sealed around shaft  16  by a spring ring  66  or other suitable mechanism. 
     Another embodiment of second barrier member  60 ′ is shown in  FIG. 4 . Second barrier member  60 ′ is defined by a first end  62 ′ and a second engagement portion  68 . The first end  6 ′ is bonded or otherwise attached to boot cover  40 . The second engagement portion  68  extends along a portion of shaft  16 . Second engagement portion  68  may be frictionally retained on shaft  16  by a clamp  48  or other suitable mechanism. 
     Another embodiment of second barrier member  60 ″ is shown in  FIG. 5 . Second barrier member  60 ″ is defined by a first engagement portion  70  and a second engagement portion  72 , with a barrier portion therebetween. The first engagement portion  70  is crimped between a portion of boot cover  40  and outer race  12 . The second engagement portion  72  extends along a portion of shaft  16 . Second engagement portion  72  may be frictionally retained on shaft  16  by a clamp  48  or other suitable mechanism. 
     Referring now to  FIGS. 6-8 , operation of first barrier membrane  50  will be explained in further detail. While  FIGS. 6-8  are discussed with reference to first barrier membrane  50 , it is understood that the principles of operation of first barrier membrane  50  are also applicable to second barrier membrane  60 ,  60 ′,  60 ″. 
     The constant velocity  10  joint is filled with a lubricant to reduce the internal temperature and lubricate the moving parts within the constant velocity joint  10 . In one embodiment the lubricant is grease, which is placed within an inner chamber of the constant velocity joint  10  and is sealed thereafter via the boot cover  40  and end cap  22 . Thus, when first barrier membrane  50  is positioned within the constant velocity joint assembly  10 , it is understood that grease may be confined between barrier membrane  50  and boot cover  40 . In those embodiments that employ a second barrier membrane  60 ,  60 ′,  60 ″, it is understood that grease may be confined between the barrier membranes  50  and  60 ,  60 ′,  60 ″. In this type of configuration, the amount of grease needed to fill the constant velocity joint assembly  10  is reduced. 
     Referring specifically to  FIG. 6 , prior to operation of constant velocity joint  10 , a force (represented by arrows  74 ) from the grease and internal pressures on barrier membrane  50  is relatively moderate. Thus first barrier membrane  50  is in an unflexed state. In such a state, expansion space  54  is at its maximum, spanning a distance D. 
     When the vehicle is operating, the constant velocity joint  10  begins rotating. This rotation causes the grease and pressures to begin to build up along the circumferential edge of the barrier membrane  50 , as seen in  FIG. 7 . 
     Due to flexible nature of the barrier membrane  50  (and second barrier membranes  60 ,  60 ′ and  60 ″), as constant velocity joint  10  continues to rotate at higher speeds and the temperature within the constant velocity joint  10  increases, the grease and pressures continue to build up behind barrier membrane  50 , causing barrier membrane  50  to expand into expansion space  54 , leaving only minimal space D between inner surface  56  of end cap  22  and barrier membrane  50 , as seen in  FIG. 8 . 
     The barrier membrane  50  expands in relation to the pressure and substantially fills expansion space  54 . However, air, water, etc. that may have been present in expansion space  54  is vented through primary orifice  24  and/or secondary orifice  26 . Because the barrier membrane  50  is substantially impermeable, contaminants cannot penetrate the barrier membrane  50  to contaminate the grease. In addition, the grease cannot leak from the constant velocity joint assembly  10  into the end cap  22  and vent through primary orifice  24  and/or secondary orifice  26 . Thus, the grease within the constant velocity joint assembly  10  is conserved. The barrier membrane  50  also prevents grease from interacting with the boot  46 , and thereby degrading and potentially causing premature failure. In addition, the use of such barrier membranes  50 ,  60 ,  60 ′, and/or  60 ″ still enables the constant velocity joint  10  to operate at any angle with no loss of grease. The barrier membranes  50 ,  60 ,  60 ′, and  60 ″ further cooperate to confine the grease to a smaller area within the constant velocity joint  10 . Therefore, the overall amount of grease necessary to lubricate the constant velocity joint is considerably reduced. Use of the barrier membranes  50 ,  60 ,  60 ′, and  60 ″ also permit the constant velocity joint assembly  10  to be used in hostile environments with no detrimental effects. 
     In prior art constant velocity joint assemblies, when the constant velocity joint  10  is spinning at its high speeds, the boot  46  may rupture prematurely because there is no venting of the internal pressure of the joint  10 . This rupture results in failures of the boot  46  and constant velocity joint  10 . Current constant velocity joints tend to use a venting hole in the center of an end cap, which does equalize joint pressure but is insufficient in obstructing water and contaminants from entering the joint. Moreover, the venting hole is also easily plugged by the lubricant within the joint. Therefore, at high pressures and temperatures within the constant velocity joint the vent mechanism must be able to equalize the internal and external pressure differences while stopping the ingress of contaminants from entering the constant velocity joint. 
     In one embodiment of the disclosure, the use of orifices  24  and/or  26  on the end cap  22  allow air to flow freely in both directions to the inside and outside of the constant velocity joint assembly  10 . However, the size of the orifices  24  and  26  on end cap  22  are sized so as to impede any water or contaminants that try to enter the constant velocity joint from the external environment. 
     The present disclosure has been described in an illustrative manner. It is understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present disclosure may be practiced otherwise than as specifically described.