Patent Application
20220235891
This disclosure relates to connectors used in conduit systems for conveying refrigerants in air conditioning systems, and more particularly to a connector having multiple seals to reduce refrigerant leakage.
It is highly desirable to reduce leakage of refrigerants from air conditioning systems to reduce emissions of greenhouse gases into the environment, to maintain the cooling capacity and functionality of the air conditioning systems, and to reduce maintenance. Moreover, the more environmentally friendly tetrafluoropropene (R1234yf) refrigerant, which is mandated for all NAFTA vehicles by the model year 2021, has a higher flammability rating than currently used refrigerants such as tetrafluoroethane (R134a), creating an additional incentive for preventing refrigerant leakage. Further, there are incentives to reduce refrigerant emissions in order to gain government issued carbon credits.
Connectors used in motorized vehicle applications typically comprise male and female connector blocks that are fastened together. These connectors typically employ a single fastener to simplify assembly and reduce time and labor. Such connectors are sometimes referred to as cantilevered conduit connectors because the fastener extends through a passage at an end of the connector opposite an end of the connector wherein the conduit passage is located, resulting in a non-uniform distribution of forces between the mating surfaces of the connector blocks. The uneven distribution of forces can cause the mating surfaces of the connector blocks to develop gaps that could allow an undesirable leakage around seals.
Disclosed is a dual plane seal connector designed to provide highly leak resistant engagement between tubular fluid conduits, while employing a single fastener. The connector includes a female connector block including a generally planar face having a conduit receiving passage in fluid communication with a second fluid conduit, and a male connector block having a generally planar face for abutting the generally planar face of the female connector. A counter-bored conduit passage is provided in the generally planar face of the male connector block. The counter-bored conduit passage includes a first cylindrical bore having a first diameter and a first depth and a second cylindrical bore coaxial with the first cylindrical bore. The second cylindrical bore has a second diameter greater than the first diameter and a second depth less than the first depth. A tubular fluid conduit extends through the conduit passage. A circumferential groove is defined in a portion of the tubular fluid conduit that protrudes outwardly from the conduit passage and away from the generally planar face of the male connector block and into the conduit receiving passage of the female connector block. A sealing ring is located in the groove to provide a radial seal, and a seal washer is located in the second cylindrical bore to provide an axial seal.
Together, these features provide a simple, inexpensive design that provides easy assembly, and reduced leakage due at least in part to the use of two independent seals, and at least in part to reduced opportunity for gaps between the mating faces of the connector blocks because the sealing washer is recessed into the face of the male connector.
Shown in
Optionally, a protuberance 34 can be provided on the generally planar face 16 of male connector block 12 to further reduce cantilever when male connector block 12 and female connector block 20 are fastened together. While protuberance 34 can be developed by machining the entire face 16 of block 12, protuberance 34 is preferably created by stamping or coining the face 16 adjacent to a fastener passage 36 to raise a predetermined amount of material to project away from face 16 (i.e., to the right in
Tubular fluid conduit 14 is provided with a circumferential groove 44 on a portion of conduit 14 that protrudes outwardly from conduit passage 22 (i.e., to the right of face 16 in
Located within circumferential groove 44 is a sealing ring 46 (e.g., an elastomeric O-ring). Sealing ring 46 includes an outward circumferential surface 48 contacting a surface of a conduit receiving passage 49 in female connector block 20, and an inward circumferential surface 50 sealingly contacting groove 44. Sealing ring 46 provides a radial seal between tubular fluid conduit 14 and conduit receiving passage 49 in female connector block 20.
As shown in
A single fastener can be used for forming a sealed connection between conduit 14 secured to male connector block 12 and a conduit 56 secured to female connector block 20. In the illustrated embodiment, female block 20 is provided with an integral threaded stud 42 that is adapted to pass through fastener passage 36. A nut 58 is used for compressing surfaces 16 and 18 together to form a fluid-tight connection. Fastener passage 36 is located between conduit passage 22 and protuberance 34.
Sealing ring 46 is preferably made of an elastomeric material. A preferred elastomeric material for sealing ring 46 is hydrogenated nitrile butadiene rubber (HNBR). Sealing ring 46 is preferably lubricated, such as with polyalkylene glycol (PAG oil) or silicon oil to allow sealing ring 46 to more easily slide along surfaces of conduit receiving passage 49 to avoid pinching and undesirable deformation of sealing ring 46 during assembly of a leak resistant connection. Alternatively, or additionally, sealing ring 46 can be provided with a polytetrafluoroethylene coating to eliminate or reduce unwanted pinching and other deformation of ring 46.
Seal washer 32 is preferably comprised of a metal (e.g., aluminum or steel) washer portion 32A that has a thickness approximately equal to the difference between the depth of counter bore 28 and the longitudinal thickness of crimped section 30, and an elastomeric portion 32B that can be made of the same elastomeric material used to make sealing ring 46, but is more preferably comprised of a different elastomer. In a particularly preferred embodiment, seal washer 32 is made of ethylene propylene diene monomer (EPDM) rubber. Having two different elastomeric materials used for washer 32 and ring 46, such as EPDM for washer 32 and HNBR for ring 46, provides better overall performance, especially under extreme conditions, such as extreme temperatures. For example, EPDM has better low temperature sealing capability and HNBR has better high temperature sealing capability. The metal washer portion 32A and elastomeric portion 32B can be mechanically joined such as with splines at interface 32C. Alternatively, or additionally, the washer portion and elastomeric portion of seal washer 32 can be chemically joined (e.g., with an adhesive material). The elastomeric portion 32B of seal washer 32 can have a tear-drop-like cross-sectional profile as shown in
Conduit receiving passage 49 preferably has walls defined by a truncated conical shape, which leads sealing ring 46 into passage 46 with reduced pinching. As an example, the half angle of the truncated conical shape can be from about 5 degrees to 25 degrees, such as 10 degrees to 20 degrees, 15 degrees to 20 degrees, or about 18 degrees.
The combination of features provides a non-cantilever seal, wherein leakage past the O-ring 46 can be blocked by seal washer 32.
Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope of the invention should be determined with reference to the appended claims along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur, and that the disclosed systems and methods will be incorporated into such future embodiments. In summary, it should be understood that the invention is capable of modification and variation.
