1. Field of the Invention
The present invention is generally related to a fuel distribution system and, more particularly, to a fuel distribution system for a marine internal combustion engine in which flexible metallic conduits are used to distribute fuel between a source and a destination.
2. Description of the Prior Art
In certain types of internal combustion engines, particularly in marine applications, it is necessary to provide fuel lines which are not susceptible to leaking when subjected to certain adverse conditions, such as extreme temperatures. For example, paragraph 6.4 of standard SAE J1527 of the Society of Automotive Engineers provides a test which include the steps of filling the hose with fuel, insuring that no air is left in the hose, insuring that the air velocity outside the system does not exceed 0.5 meters per second, pouring heptane into a fuel pan a prescribed distance between the test subject hose, allowing the heptane to burn for 150 seconds, and opening a valve so that fuel can flow through the hose under test. The hose is then subjected to a hydrostatic pressure corresponding to 35.4 inches of fuel and inspected for signs of leakage. This type of testing, and other test procedures, require that a fuel line exhibit a high degree of temperature and pressure resistance under very adverse conditions.
Three known procedures have been used to satisfy the stringent conditions described above. First, rigid metal tubing can be formed to traverse a path between a liquid fuel source, such as a fuel pump, and a liquid fuel destination, such as a fuel rail of a fuel injected system or a carburetor. A second method is to provide a fire sleeve which completely surrounds the fuel line and extends the entire length of the fuel line between the liquid fuel source and the liquid fuel destination. A third procedure is to use coated and braided hose assemblies that have been proven to be sufficiently temperature and abrasion resistant to satisfy the rigorous tests required for fuel lines.
Many types of fire resistant and abrasion resistant conduits are known to those skilled in the art. U.S. Pat. No. 5,142,782, which issued to Martucci on Sep. 1, 1992, discloses a coated braided hose method and assembly. A method is provided for making a lightweight hose assembly including a step of extruding the inner liner. A nonmetallic material is then braided about the exterior of the liner. The inner liner and braided layer are then passed through a reservoir containing a solution of the fluorocarbon polymer. The solvent is then removed, leaving fluorocarbon polymer coating dispersed throughout the braided layer.
U.S. Pat. No. 5,170,011, which issued to Martucci on Dec. 8, 1992, described a hose assembly. The lightweight hose assembly of the type adapted for conveying fuels and other corrosive fluids, is disclosed. The assembly includes a tubular inner liner comprising a polymeric fluorocarbon material resistant to chemical and heat degradation, and is characterized by including an outer liner comprising an expanded polyamide material disposed about the inner lining. The assembly further includes a conductive strip formed along the inner liner for dissipating electrical charges accumulating along the inner liner.
U.S. Pat. No. 5,192,476, which issued to Green on Mar. 9, 1993, describes a method for forming a conduit by pre-coating the conduit prior to braiding. The method described is for forming a hose assembly of the type adapted for carrying fuels and other corrosive fluids. An inner liner of a fluorocarbon material is extruded. The inner liner is then passed through a reservoir containing a dispersion including a fluorocarbon polymer material and a fluid. Glass fibers are then braided about the exterior of the inner liner to form a braided layer having the dispersion thereabout such that the dispersion penetrates the interstitial spaces of the braided layer. Subsequently, the assembly is heated to remove the fluid. The assembly is then sintered to cure the fluorocarbon polymer material into a coating dispersed throughout the braided layer and about the inner liner.
U.S. Pat. No. 3,743,328, which issued to Longfellow on Jul. 3, 1973, describes a gas appliance connector. A flexible metal tubing forms a connector and has a wall thickness of from 0.020 inches to 0.064 inches and is corrugated by two helical corrugations, the coils of which are in alternate arrangement.
U.S. Pat. No. 5,538,294, which issued to Thomas on Jul. 23, 1996, describes a corrugated flexible metal piping assembly. The assembly includes a body with corrugations having spiral or annular configurations. End connections are mounted on the body ends, which can be flanged or male-threaded. A layer of insulating or sealing material can be applied over the body. The end connections can be male-threaded or female-threaded. A bellows configuration is provided with annular corrugations which taper in proximity to the body ends.
U.S. Pat. No. 2,848,254, which issued to Millar on Aug. 19, 1958, discloses end fittings for flexible metal hoses. An end fitting is provided for a corrugated metallic hose having at least one surrounding tubular reinforcement, with the end fitting comprising an annular gripper sleeve having an internally grooved part which receives a plurality of the external corrugations of the end portions of the hose lying therewithin, with the corrugations at the front extremity of said hose projecting forwardly beyond the grooved part of the sleeve.
U.S. Pat. No. 3,549,176, which issued to Contreras on Dec. 22, 1970, describes a flexible flow liner for a bellows joint. The flexible corrugated bellows connects two flanged tubes of a fluid line. A liner is disposed within the bellows and is fabricated of woven wire braid. One end of the liner is fixed to one of the tubes and the other end has a guide which is slidable within the outer tube.
Flexible metallic conduits are available in commercial quantities from Airmo Inc. The flexible metallic conduits are manufactured with cylindrical surfaces that are shaped to comprise a plurality of folds to form a bellows shape which affords a certain degree of flexibility to the resulting tubular structure.
All of the patents described above are hereby explicitly incorporated by reference in the description of the preferred embodiment.