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  Fuel tank venting systemThe Patent Description & Claims data below is from USPTO Patent Application 20060157117. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This is a continuation-in-part patent application taking priority from a utility patent application having Ser. No. 10/846,296 filed on May 14, 2004. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to venting fuel tanks and more specifically to a fuel tank venting system, which may be located in a fuel cap or in a wall of the fuel tank. [0004] 2. Discussion of the Prior Art [0005] Fuel tanks used with small engines usually allow fuel vapors to continually vent to the atmosphere. Sometimes check valves are incorporated in the gas cap to prevent the escape of fuel vapors. Some types of check valves seal well under high pressure, but allow fuel vapor seepage under low pressure. With marine fuel tanks, a thumb screw in the fuel cap is used to seal the marine fuel tank, when not in use. The thumb screw is opened in most cases to run the engine. During the time when the engine is running, fuel vapors are vented to the atmosphere. Some users may never tighten the thumb screw for the sake of convenience, allowing the escape of fuel vapors from the marine fuel tank, at all times. [0006] Accordingly, there is a clearly felt need in the art for a fuel tank venting system to prevent fuel vapors from being vented to the atmosphere, while allowing atmospheric air to enter the fuel tank for the purpose of fuel flow. SUMMARY OF THE INVENTION [0007] The present invention provides a fuel tank venting system for the purpose of providing fuel flow to an engine. The fuel tank venting system includes a fuel cap, a vent diaphragm and a vent disc. An air filter is preferably disposed in a top of the fuel cap. A threaded bore is formed in a bottom of the fuel cap to threadably receive a fuel tank fill spout. A valve cavity with a substantially concave bottom is formed adjacent the threaded bore. The vent disc preferably includes a disc flange and a diaphragm projection. At least one air passage is formed through the disc flange. A disc counter bore is formed in a bottom of the fuel cap, adjacent the valve cavity to receive the disc flange of the vent disc. A substantially convex surface is preferably formed on a top of the diaphragm projection. The vent diaphragm is retained between the substantially concave bottom of the valve cavity and the substantially convex surface of the diaphragm projection. The vent diaphragm is fabricated from a flexible material with memory. When air is needed for fuel flow, a vacuum within the fuel tank pulls the perimeter of the vent diaphragm downward, which breaks a seal with the substantially concave bottom. Air flows around the unsealed perimeter of the vent diaphragm through the at least one air passage. When the vacuum ceases, the vent diaphragm returns to its original sealing position, which does not allow fuel vapors into the atmosphere. [0008] A second embodiment of the fuel tank venting system includes a vent body, the vent diaphragm and the vent disc. An air filter is preferably disposed in a top of the vent body. A body opening is preferably formed in a wall of a fuel tank that is sized to receive an outer perimeter of the vent body. A valve cavity with a substantially concave bottom is formed in a bottom of the vent body. A disc counter bore is formed in a bottom of the vent body to receive the disc flange of the vent disc. The vent diaphragm is first inserted into valve cavity. The vent disc is then inserted into the disc counter bore. The vent diaphragm is retained between the substantially concave bottom of the valve cavity and the substantially convex surface of the diaphragm projection. [0009] When air is needed for fuel flow, a vacuum contained in the fuel tank pulls the perimeter of the vent diaphragm downward, which breaks a seal with the substantially concave bottom. Air flows around the unsealed perimeter of the vent diaphragm through the at least one air passage. When the vacuum ceases, the vent diaphragm returns to its original sealing position, which does not allow fuel vapors into the atmosphere. [0010] A third embodiment of the fuel tank venting system includes a fuel vent body, the vent diaphragm and the vent disc. An air filter is preferably disposed in a top of the fuel vent body. A clearance opening is preferably formed in a wall of a fuel tank that is sized to allow air flow through the vent disc. A valve cavity with a substantially concave bottom is formed in a bottom of the fuel vent body. A disc counter bore is formed in a bottom of the vent body to receive the disc flange of the vent disc. The vent diaphragm is first inserted into valve cavity. The vent disc is then inserted into the disc counter bore. The vent diaphragm is retained between the substantially concave bottom of the valve cavity and a substantially convex surface of the diaphragm projection. [0011] A fuel pass through is also formed in the fuel vent body. Preferably, a first fuel bore is formed in a bottom of the fuel vent body and a second fuel bore is formed in a side of the fuel vent body. The first fuel bore communicates with the second fuel bore to allow the flow of fuel therethrough. A first fuel tube is inserted into the first fuel bore and a second fuel tube is inserted into the second fuel bore. One end of a first fuel hose is terminated with a fuel filter and the other end is secured over the first fuel tube. One end of a second fuel hose is secured over the second fuel tube and the other end is connected to an internal combustion engine. [0012] When air is needed for fuel flow, a vacuum contained in the fuel tank pulls the perimeter of the vent diaphragm downward, which breaks a seal with the substantially concave bottom. Air flows around the unsealed perimeter of the vent diaphragm through the at least one air passage. When the vacuum ceases, the vent diaphragm returns to its original sealing position, which does not allow fuel vapors into the atmosphere. [0013] Accordingly, it is an object of the present invention to provide a fuel tank venting system to prevent fuel vapors from being vented to the atmosphere, while allowing atmospheric air to enter the fuel tank for the purpose of fuel flow to an engine. [0014] These and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification. BRIEF DESCRIPTION OF THE DRAWINGS [0015] FIG. 1 is a cross sectional view of a fuel tank venting system contained in a fuel cap, the fuel cap is retained on a fuel spout of a fuel tank in accordance with the present invention. [0016] FIG. 2 is a bottom view of a fuel cap of a fuel tank venting system contained therein in accordance with the present invention. [0017] FIG. 3 is a cross sectional view of a second embodiment of a fuel tank venting system retained in a wall of the fuel tank in accordance with the present invention. [0018] FIG. 4 is a cross sectional view of a third embodiment of a fuel tank venting system retained adjacent a wall of the fuel tank in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0019] With reference now to the drawings, and particularly to FIG. 1, there is shown a cross sectional view of a fuel tank venting system 1. With reference to FIG. 2, the fuel tank venting system 1 preferably includes a fuel cap 10, a vent diaphragm 12 and a vent disc 14. A filter cavity 16 is preferably formed in a top of the fuel cap 10 to receive an air filter 18. A threaded bore 20 is preferably formed in a bottom of the fuel cap 10 to threadably receive a fuel tank fill spout 102 of a fuel tank 100. A valve cavity 22 with a substantially concave bottom 24 is formed adjacent the threaded bore 20. A flow passage 19 is formed through the filter cavity 16 to the substantially concave bottom 24. The vent disc 14 preferably includes a disc flange 26 and a diaphragm projection 28. A disc counter bore 29 is formed in a bottom of the fuel cap, adjacent the valve cavity 22 to receive the disc flange 26. The vent disc 14 is retained in the disc counter bore 29 with a force fit, adhesive or any other suitable method. At least one air passage 30 is formed through the disc flange 26, but may be formed through the diaphragm projection 28. A substantially convex surface 32 is preferably formed on a top of the diaphragm projection 28. A seal gasket 33 may be retained, adjacent a bottom of the disc flange 26. Continue reading... Full patent description for Fuel tank venting system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Fuel tank venting system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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