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An improved oil filler cap is presented, designed to support the reintroduction of super clean oil from a bypass oil filter attached to a gasoline or diesel engine. The improved filler cap is designed to be shorter in height than state-of-the-art bypass filler caps, removing an unneeded structure supporting the nozzle receiving the super clean oil. This invention is directed towards vehicles with low hood clearance in their engine compartments.

Meddock, Mark (Oceanside, CA, US)
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Primary Examiner:
Attorney, Agent or Firm:
STEVEN W. WEBB (Oceanside, CA, US)
What is claimed is

1. an improved engine oil filler cap, the engine oil filler cap comprised of a filler cap, an O-ring, a swivel plug, a snap ring, a swivel nozzle, and an oil filler cap gasket, the filler cap possessing a cylindrical hole through its center, the cylindrical hole lined with a cylindrical hole gasket on its circumference, the swivel plug possessing a cylindrical receptacle threaded with screw threads, the swivel nozzle possessing an input and a cylindrical lower part covered with screw threads.

2. A method of assembling an engine oil filler cap as in claim 1, the method comprised of the steps of inserting an O-ring into the circumference of the cylindrical hole in the filler cap, fitting the swivel plug into the cylindrical hole of the filler cap until it seats, inserting the snap ring above the swivel plug under the rim of the cylindrical hole, screwing the swivel nozzle into the cylindrical receptacle of the swivel plug until it seats, inserting the oil filler cap gasket into the underside of the filler cap, screwing the entire assembly onto an oil filler opening.

3. A method of using the engine oil filler cap as in claim 1, comprised of the steps of assembling the oil filler cap as in claim 2, attaching the output from a bypass oil filter, an oil cooler, or both to the input of the swivel nozzle.



The present invention relates generally to lubrication fluid filtration and fluid temperature control components and systems for internal combustion engines, gasoline, diesel, and compressed natural gas (CNG) and more particularly to a means for conveniently flowing the lubricating fluid back into the engine.


There are generally two methods of fluid filtration used to clean the lubricating oil for internal combustion engines. One method, which is used by virtually all internal combustion engines, is commonly referred to within the industry as full flow filtration. Full flow filters receive oil under pressure from the engine oil pump, direct the oil under the same pressure to flow through the filtering element and then under pressure to flow through the engine's internal oil passageways to all the lubricated components. The oil, then under zero or very low pressure will flow by gravity back to the oil sump for the cycle to repeat.

The other method of fluid filtration is to add to the engine full flow lubricating system a secondary filter with a much denser filtering media for the purpose of filtering the oil to a much cleaner level than is possible with full flow filtration only This secondary filter is commonly referred to as a bypass filter.

Typically, bypass filters are separate devices and are plumbed to receive oil under pressure from a pressurized port on the engine and return the oil to the sump under zero or very low pressure. Bypass filters typically receive only about 5-10% of the volume of oil that flows through the full flow filter and are generally effective to “superclean” the oil.

The larger truck and bus type diesel and CNG engines usually are provided by their manufacturer with one or more oil pressure ports and non-pressurized oil return ports. These are typically utilized for the installation of a bypass filter. The smaller diesel engines, such as those used for pick-up trucks, small delivery vans, and passenger automobiles as well as most automotive gasoline engines are not usually equipped with a pressurized oil port and even more rarely with a non-pressurized port to receive the return flow from a bypass filter or an aftermarket oil cooler.

This invention pertains to the return of oil from the bypass filtration unit to the lubrication system of internal combustion engines.

In applications where there is need to return the superclean oil from a bypass filter and a non-pressurized port is not available, it has become common practice to modify the oil filler cap to receive a fitting that the oil return hose can be connected to. While this makes it possible to return the oil to an engine that does not otherwise have a non-pressurized port, it is still inconvenient because the hose connection must first be loosened in order to twist or unscrew the oil filler cap to remove it in order to add engine oil. Oil return from an oil cooler can also be directed to the oil filler cap, and the present invention addresses this need as well.

The inconvenience of having to loosen the hose connection has been addressed in prior art devices where a swiveling hose connection fitting is available to be retrofitted to an oil filler cap. While nominally solving one problem, these swivel devices tend to add additional height to the oil filler cap that sometimes interferes with the hood closure on certain vehicles with low profile engine compartment hoods.

The present invention addresses a specific requirement for some vehicle engines that need a low-profile engine oil filler cap with an input swivel mount that is short enough to fit under stock engine compartment hoods.


It is an object of the present invention to provide an after-market oil filler cap to meet the requirements for fitting under the engine compartment hood for specific gasoline and diesel vehicles.

It is an object of the present invention to provide such an oil filler cap in an improved, screw-and-lock-down version.

It is an object of the present invention to provide such an oil filler cap with a swivel nozzle for connection to the bypass oil filter output or oil cooler output.

It is an object of the present invention to provide this invention in a low-cost implementation.


The present invention provides a shorter swiveling pipe fitting on the top of an after market oil filler cap, compatible with bypass filter outflows from dual flow oil filters, from separate bypass filters operating alongside standard full-flow-oil filters, or from oil coolers. The present invention is also compatible with OEM connector methodology, designed to mate with all available connecting methods for filler nozzles.

The invention provides a substantially shorter swiveling pipe fitting than do state of the art swivel designs for oil filler caps. The swiveling pipe fitting is mated into the body of the oil filler cap without the extender that is provided by the state of the art system. The present invention eliminates the need for a swivel body supporting the pipe fitting, providing a substantially shorter swiveling pipe fitting.

Another important feature of the present invention is that it brings the center of gravity of the oil filler cap swiveling pipe fitting down and conveys greater rigidity to the structure by virtue of a shorter lever arm for forces to act on. With a swiveling pipe fitting extending above the oil filler cap several inches less, the oil filler cap can be used in vehicles with low hood clearance, such as the Ford Motor Company 2003 and subsequent year Crown Victoria and Mercury Marquis. Other vehicles can be serviced by this oil filler cap as well.

There are definite advantages to adding an auxiliary filter to an engine, plus an auxiliary compatible oil filler cap after market. The present invention confers many of these advantages


FIG. 1. Prior art filler cap side view

FIG. 2. Prior art filler cap cross section

FIG. 3. Side view of the invention alternate embodiment

FIG. 4. Cross-section view of the invention

FIG. 5. Exploded view of the invention


As shown in FIG. 1 and FIG. 2, the prior art oil filler cap 100 compatible with a bypass filter output possess an oil filler cap 105, an O-ring 102, a swivel plug 101, a retaining ring 104, and an oil filler cap gasket 103. There is an oil filler cap swivel mount 107 that rests in an oil filler cap bore hole 108. The swivel mount 107 serves as a base for the swivel holder 101 and swivel nozzle 109 that connects to a hose leading from the bypass output of the oil filtration system (not shown).

The length of the swivel mount 107 forces the swivel nozzle 109 several inches above the top of the oil filler cap 105. This distance prevents the use of the prior art device in certain vehicles due to clearance under the engine compartment hood when the hood is closed.

In FIG. 4 and FIG. 5, the present invention 120 is shown to possess similar features as follows: an oil filler cap 125, an O-ring gasket 122, a snap ring 124, and an oil filler cap gasket 123. The present invention 120 does not possess a swivel mount 107 as does the state of the art device. Rather, a cylindrical hole 128 has been provided and an O-ring gasket 122 is placed around the circumference of the swivel holder 130 which is fitted into the oil filler cap 125, held in place by the snap ring 124 and the swivel nozzle 129 screwed into the swivel holder 130. Removing the swivel mount 107 and replacing it with a direct connection between the oil filler cap 125 and the swivel holder 130 shortens the invention 120 compared to the prior art device 100, permitting its use in a larger number of vehicles with low hood clearances.

In FIG. 3 and FIG. 5, the lock-down screw slot 132 is shown, whereby the cap can be locked down onto the oil filler opening (not shown) when such a feature is available on the vehicle oil filler opening.

This invention has other applications, potentially, and one skilled in the art could discover these. The explication of the features of this invention does not limit the claims of this application; other applications developed by those skilled in the art will be included in this invention.