This invention relates generally to the field of seal fittings. In particular, this invention relates to a frusto-conical seal fitting designed for low permeation of pressurized fluids such as refrigerants.
In certain systems such as air conditioning systems in automobiles, it is necessary to provide a pathway for pressurized fluid such as Freon or other refrigerants. These pathways are commonly constructed of metal tubing and include numerous fittings as a way of linking sections of tubing together, linking componentry and simplifying construction of the pathways. The sizes and shapes of these parts may be adjusted as required.
However, the fittings may become vulnerable to leaks and other structural weaknesses in the pathway. This can result in a loss of some pressurization, or xe2x80x9cpermeation,xe2x80x9d and reduces the amount of fluid in the system. The loss of pressurization reduces the efficiency of the system and can lead to further damage to the system.
Many different techniques have been utilized to reduce the permeation of gas or fluid out of a closed system utilizing fittings. These techniques reduce permeation in a limited fashion, but it is desirable to reduce permeation even further. U.S. Pat. No. 3,368,832, for example, discloses a conduit and tube coupling for use in a system containing pressurized fluid or gas. The conduit and tube coupling consists of three separate components and an o-ring to complete the seal. An area is provided within the interior of the outer piece such that when the two inner pieces are secured together, one of the inner pieces expands outwardly into the open area of the outer piece. The o-ring seals the space between one inner piece and the outer piece. The expansion of the inner piece and the o-ring act to create a seal in the coupling and to prevent pressurized gas or fluid from escaping. However, the o-ring used in this invention is relatively thin. The thin material can allow some pressurized gas or fluid to permeate slowly from the system over time.
As another example of the prior art, U.S. Pat. No. 5,082,243 discloses a coupling for a gas container utilizing a metallic washer and a sloped surface. The washer contacts the sloped surface and provides a seal for a fitting in a system containing pressurized gas. The fitting consists of three components: a male component, a female component and a washer having a conical shape. A nut is positioned over the outside of the female component to hold the components together. The washer is positioned between a sloped surface of the female component and a sloped surface of the male component. The metal washer does not allow gas or fluid permeation over the life of the system. However, metal washers necessitate a near perfect fit, and are not forgiving to imperfections in the surfaces of the components. This creates an extra expense due to the complexity of the manufacturing process.
Other patents have also addressed the permeation problem in this type of system. For example, Italian Pat. No. 571178 illustrates a conical seal similar to the ""243 patent. A thick conical seal is shown between two smooth sloped mating surfaces, once again increasing the path necessary for permeation. French Pat. No. 889.819 also illustrates a similar concept, except that the conical seal is even longer, increasing the permeation path to a greater extent.
French Pat. No. 1.463.952 illustrates a fitting similar to the ""832 patent. An area of one component of the fitting is expanded into an open area in another component to complete the seal. Steps are defined in the open areas of the female component that create a tighter seal once the interior component is expanded. A separate sealing piece is not used in this design.
Russian Pat. No. 974,016 illustrates the use of a component with steps on its exterior surface. The component is mated with a union nipple having annular inclined elements in the shape of a comb and corresponding to the steps in the piece. The annular elements contact the steps and provide a metal-to-metal seal. Again, the metal-to-metal seal necessitates extremely precise manufacturing.
All of these inventions improve the efficiency of a system containing pressurized gas or fluid. However, it is still desirable to improve the efficiency of this type of fitting.
In one embodiment of the present invention, a seal fitting includes a generally frusto-conical male component with a plurality of annularly stepped portions on its exterior surface and an annularly extending groove defined on one end. A frusto-conical elastomeric seal is also provided in contact with the stepped portions on the male component and a female component is provided that has a frusto-conical opening adapted to receive the male component and compress the frusto-conical seal between the male and female components.
In another embodiment of the present invention, a seal fitting includes a generally frusto-conical male component with a plurality of annularly stepped portions on its exterior surface and an axially extending passage defined within the male component. A frusto-conical seal is provided to substantially cover the exterior surface and the stepped portions on the male component. A female component is provided with a frusto-conical opening defined in its interior to receive the male component. The female component also has an axial passage defined within its interior.
In yet another embodiment of the present invention, a seal fitting includes a generally frusto-conical male component having a first end, a second end and an exterior surface. A frusto-conical seal adapted to cover at least a portion of the male component is provided along with a female component having a first and a second end. A frusto-conical opening is defined in axially within the female component and a plurality of stepped portions extend from at least one of the male and female components.
The invention may also be embodied in a method for preventing the permeation of pressurized fluid from a fitting. The method includes the steps of providing a male component having a generally frusto-conical exterior surface with a plurality of annularly extending steps on its exterior surface and an axially extending passage defined therein and a female component with a frusto-conical opening on one end and a passage extending axially therein. The method also includes the step of placing a seal adapted to conform to the exterior surface of the male component over the male component and inserting the male component into the frusto-conical opening of the female component so that the seal is compressed between the components.