This present invention relates to vent-valve assemblies and, particularly, to a pressure-relief and vacuum-relief valve subassembly for a fuel tank filler neck cap. More particularly, the present invention relates to a self-contained pressure-relief and vacuum-relief valve subassembly which is designed for insertion into a filler neck cap.
Conventional pressure-relief and vacuum-relief valves are generally well-known items and are currently in widespread use. See, for example, U.S. Pat. No. 4,498,493 to Harris and U.S. Pat. No. 4,779,755 to Harris. Although pressure-relief and vacuum-relief valves are currently in widespread use, it would be desirable to provide an alternative assembly that is simpler to assemble and to install into a fuel cap.
More and more vehicles are subjected to extreme fluctuations in pressure and vacuum conditions within their fuel tanks and thus need filler neck caps having a pressure-relief and vacuum-relief valve provided therein. It is sometimes difficult to install conventional pressure-relief and vacuum-relief valves into the caps during assembly. A pressure-relief and vacuum-relief valve subassembly that is self-contained and which is readily inserted into a housing of a filler neck cap would be a welcome improvement over conventional pressure-relief and vacuum-relief valves. What is needed is a self-contained vent-valve assembly that is easily inserted into a filler neck cap during assembly.
According to the present invention, a self-contained vent-valve assembly is provided for use in a filler neck cap. The vent-valve assembly includes a valve housing and means for channeling ambient air and fuel vapor through the valve housing. The channeling means includes a vacuum-relief valve subassembly which is spring-biased within the housing and a pressure-relief valve subassembly which rides upon the vacuum-relief valve subassembly. The valve housing and channeling means cooperate to form an easy-to-assemble, self-contained, vent-valve assembly.
In preferred embodiments of the present invention, the vacuum-relief valve subassembly includes a vacuum-relief valve and a vacuum-relief spring. The vacuum-relief valve itself includes a valve member which rests upon the vacuum-relief spring and guide legs which depend from the valve member around the vacuum-relief spring. The vacuum-relief valve is retained in the valve housing by flanges or feet which extend out from the guide legs and engage the valve housing. Illustratively, the vacuum-relief valve includes three guide legs that are arranged in spaced-apart relation about the circumference of the valve member.
Furthermore, the pressure-relief valve subassembly is mounted within the housing to lie above the vacuum-relief valve subassembly. The pressure-relief valve subassembly includes a pressure-relief spring, an annular valve plate, and a pressure-relief valve which is coupled to the annular valve plate. Following assembly, the pressure-relief spring applies a biasing force to urge the pressure-relief valve downwardly against a circular lip provided in the housing and the underlying spring-loaded vacuum-relief valve.
The housing itself has a body that is tubular in shape and has an inner end, an outer end, and an air passageway extending therethrough. This tubular body further includes the circular lip and a valve brace. Illustratively, the lip extends into the air passageway for engagement with the flanges of the guiding legs to spring-bias the vacuum-relief valve within the valve housing. Furthermore, the valve brace includes three downwardly depending L-shaped legs which are arranged in spaced-apart relation about the circumference of the lip to provide a mount for the vacuum-relief spring. Thus, both the vacuum-relief valve subassembly and the pressure-relief valve subassembly are positioned within the air passageway of the tubular housing and are ready for easy installation into a fuel cap.
The initial development was undertaken to create a high vacuum flow valve. Due to the spring required to meet the flow specifications, it was necessary to create a means of retaining the vacuum valve and spring to the housing prior to the assembly of the pressure-relief valve.
The function of the vacuum valve is to allow atmospheric air into the tank during vacuum conditions. The sub-assembly of the vacuum valve to the housing is necessary to hold the valve in place prior to the assembly of the pressure-relief valve. This is accomplished by fingers with snaps extending from the body of the valve radially which snap into the housing and retain the spring and vacuum valve during assembly. The valve assembly in accordance with the present invention allows for an easier assembly by retaining the vacuum valve and spring prior to the installation of the pressure-relief valve.
It is quite simple to put together a vent-valve assembly in accordance with the present invention. The user must only extend the vacuum-relief spring through the outer end of the valve housing and place it upon the valve brace. Once in place, the vacuum-relief spring is released so that it extends in an upward direction past the lip. At this time, the user places the vacuum-relief valve upon the spring and presses it in the downward direction toward the brace until the flanges snap past the lip. The snapping sound serves as an indication to the user that the vacuum-relief valve subassembly is securely locked within the valve housing to form a convenient self-contained vent-valve subassembly.
Once the vacuum-relief valve assembly is secured within the housing, the user simply fastens the pressure-relief valve and the annular valve plate together and places them into the outer end of the valve housing so that the pressure-relief valve sits upon the vacuum-relief valve. The user completes the construction of the vent-valve assembly by inserting the pressure-relief spring through the outer end of the valve housing and placing it upon the annular lip. Illustratively, the self-contained vent-valve assembly is inserted into one of a variety of available fuel caps to regulate the flow of ambient air and fuel vapors into and out of a fuel tank filler neck.
A user of the vent-valve assembly in accordance with the present invention will find that the vacuum-relief valve which is coupled for movement within the valve housing before installation of the pressure-relief valve therein makes the vent-valve assembly easier to assemble and use than traditional vacuum-relief and pressure-relief valves.
Additional objects, features, and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.