.Iadd.This application is a continuation of Ser. No. 08/086,047, filed Jun. 30, 1993, now abandoned, which is a reissue of Ser. No. 07/910,415, filed on Jul. 8, 1992, now U.S. Pat. No. 5,207,811. .Iaddend.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to air filters and, more particularly, to heavy duty air filters including a gasket mounted thereon to prevent the flow of unfiltered air about the filter.
2. Summary of Related Art
Air filters are well known devices wherein air is drawn or forced into a housing and caused to pass through a filter unit having a full flow filter media to remove the dirt and dust particles carried in the air. Substantially clean air is thereby passed to the point of usage, such as an internal combustion engine. Large, heavy duty air filters are utilized on heavy equipment, such as trucks and earth movers. Such air filters have heretofore generally included an annular foamed rubber gasket bonded to the substantially flat end cap of the filter unit with an adhesive. The gasket seals the inlet from the outlet of the housing, so that no air will pass through the outlet without first having passed through the filter unit. Typically, the gasket is compressed between the end cap of the filter unit and the end wall of the housing by the manual tightening of a bolt which urges the filter unit into sealing engagement against the end wall of the housing.
While the mounting of the foamed rubber gasket to the end cap by means of an adhesive is almost universally practiced, and has been for many years, this construction has a number of disadvantages, the significance of which were not heretofore appreciated. Thus, the gasket, which in air filters is generally formed of a foamed rubber material, tends to lose its stability and concentricity as the filter unit is forced against the housing end wall. Further, it is believed that users often overtighten the bolt, thereby subjecting the gasket to excessive compressive forces and potentially causing permanent deformation of the gasket. As a result, the integrity of the seal provided by the gasket is often compromised. Finally, the bonding of the gasket to the housing end cap makes it difficult if not impossible to remove and replace the gasket. Replaceability of the gasket is desirable if, for example, the filter unit is of the type which is cleaned and reused.
SUMMARY OF THE INVENTION
The present invention relates to an air filter assembly comprising a filter housing having opposing end walls and a side wall between the end walls. The housing has an air inlet and an air outlet formed therein. A filter media is mounted within the housing and is interposed between the inlet and outlet of the housing. An end cap is mounted to one end of the filter media, the end cap having an annular groove formed therein. A gasket formed of a resilient, pliable material is mounted within the groove. The assembly is provided with means for urging the end cap against an adjacent end wall of the housing to compress the pliable gasket therebetween, thereby sealing the inlet from the outlet so that no air can pass out of the outlet without having first passed through the filter media.
The novel construction of the present invention is advantageous in that the side walls of the groove protect the gasket from sliding and collapsing, ensuring the stability and concentricity of the gasket. Furthermore, the walls defining the groove serve to limit the amount of potentially damaging compressive force which may be applied to the gasket through the manual tightening of the bolt. As the gasket is retained with a groove, the need to use an adhesive to permanently bond the gasket to the end cap is eliminated, facilitating replacement of the gasket.
While somewhat similar grooves have been used in conjunction with the sealing gasket on spin-on oil filters for many years, there are many important distinctions between oil filters and air filters which presumably have not led others to employ a structure similar to the present invention on air filters. Such distinctions include the widely differing temperature and pressure conditions experienced by oil filters and air filters. Oil filters typically operate at much higher temperatures and pressures than do air filters. Thus, the gaskets for oil filters are generally formed of a rigid, relatively hard rubber material, while the gaskets for air filters are formed of a resilient, pliable foamed rubber material. Air filter gaskets are thus much more susceptible to deformation and loss of concentricity than are oil filter gaskets. In view of the different environments, the advantages of the present invention were not heretofore appreciated.
BRIEF DESCRIPTION OF THE DRAWINGS
The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:
FIG. 1 is a longitudinal sectional view of the an air filter in accordance with the present invention;
FIG. 2 is an enlarged view of a portion of the air filter of FIG. 1 after tightening;
FIG. 3 is an enlarged sectional view of one embodiment of the housing end cap and gasket of the present invention;
FIG. 4 is an enlarged sectional view of a second embodiment of the housing end cap and gasket;
FIG. 5 is an enlarged sectional view of a third embodiment of the housing end cap and gasket;
FIG. 6 is an end view of a fourth embodiment of the housing end cap and gasket; and
FIG. 7 is an enlarged sectional view taken along
line 7--7 of FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, there is illustrated in FIG. 1 an air filter assembly in accordance with the present invention including a housing generally designated 10 having a filter unit generally designated 12 mounted therein. The
housing 10 is formed of an
upper portion 14 and a
lower portion 16 which are held together by any appropriate means, such as by a
clamping ring 18. The
side wall 20 of the
upper portion 14 is provided with an
inlet 22 near the top thereof, and the top or
end wall 24 of the
housing 10 is provided with an
outlet 26. The bottom of the housing is closed by a
bottom wall 28.
The
filter unit 12 is comprised of a
filter media 30 which is typically made of pleated paper which may or may not be treated with a moisture resistant material. The pleated
paper filter media 30 is protected by
inner tube 32 and
outer tube 34, both formed of a foraminous material, such as perforated metal.
The
filter unit 12 is further provided with an
end cap 36, typically formed of a suitable metal, at the lower end thereof. The
end cap 36 has an
outer flange 38 which abuts the lower end of the
outer tube 34 and an
inner flange 40 which abuts the lower end of the
inner tube 32 to retain the
outer tube 34,
inner tube 32 and
filter media 30 in position. The inner portion of the
end cap 36 extends upwardly and inwardly to form a dome-
like structure 42 within the
inner tube 32. This dome-
like structure 42 is provided with a substantially
fat center portion 44 having an
opening 46 therein. A
spider 48 is mounted at the
outlet 26, extending downwardly and inwardly therefrom to fixedly engage the end of a
bolt 50 which extends through the
opening 46. The
bolt 50 is provided with an associated
wing nut 52 and sealing
washer 54, with the
washer 54 engaging the
flat center portion 44 of the
end cap 36 to retain the
filter unit 12 in position within the
housing 10.
As best seen in FIG. 2 the upper end of the
filter unit 12 is likewise provided with an
end cap 56, also typically formed of a suitable metal. The
end cap 56 includes an
outer flange 58 which abuts the upper end of the
outer tube 34, and an
inner flange 60 which abuts the upper end of the
inner tube 32. The
upper end cap 56 is sealed to the upper end of the pleated
paper filter media 30 by any suitable means such as by means of an adhesive.
A
gasket 62 formed of a suitable pliable material preferably foamed rubber, is mounted in a
groove 64 formed in the
end cap 56. The
groove 64 is preferably formed by providing a pair of radially spaced
annular projections 66 extending from the
end cap 56 away from the
filter media 30. The base of the
groove 64 thus remains coplanar with the remainder of the
end cap 56, abutting the end of the
filter media 30. The
end cap 56 may be formed on a stamping press from a single sheet of metal by employing various dies to form the
end cap 56 and
groove 64.
The
gasket 62 is compressed between the
end cap 56 of the
filter unit 12 and the
top wall 24 of the
housing 10 by tightening the
wing nut 52 on the
bolt 50, which forces the
filter unit 12 against the
top wall 24 of the
housing 10. The
gasket 62 thus provides a seal between the
upper end cap 56 and the
end wall 24 of the
housing 10, thereby sealing the
inlet 22 to the
housing 10 from the
outlet 26 and insuring that air passing through the
outlet 26 must first pass through the
filter media 30 of the
filter unit 12.
The
projections 66 forming the
groove 64 support the
gasket 62 laterally and prevent it from sliding and collapsing upon tightening of the
wing nut 52 on the
bolt 50, thereby ensuring the stability of the
gasket 62. Retaining the
gasket 62 in the
concentric groove 64 also virtually eliminates any loss of concentricity which would otherwise be experienced by the
gasket 62 during use of the filter assembly.
When properly tightened, the
gasket 62 is generally compressed from about 20 to 25 percent. However overtightening is not uncommon, and potentially results in permanent deformation of the
gasket 62. The tightening of the
wing nut 52 on the
bolt 50 urges the
filter unit 12 towards the
top wall 24 of the
housing 10, compressing the
gasket 62 between the
end cap 56 of the
filter unit 12 and the
top wall 24 of the
housing 10. The
projections 66 forming the
groove 64 serve to limit the amount of potentially damaging compressive force which may be applied to the
gasket 62 through the manual tightening of the
bolt 50. No additional compressive force is applied to the
gasket 62 once the
projections 66 contact the
top wall 24 of the
housing 10. Thus, the height of the
projections 66 controls the extent to which the
gasket 62 may, at a maximum, be compressed.
Furthermore, while FIG. I shows the air filter mounted vertically, in some applications the space available requires that the filter be mounted horizontally. In such applications, the weight of the
filter unit 12 tends to cause the outer end of the unit to sag. With the prior art filter gaskets, this subjected the bottom portion of the gasket to additional compressive forces while reducing the compressive force against the upper portion of the gasket to the point where the seal was not effective. User response was typically to further tighten the wing nut on the bolt, often resulting in failure of the gasket. With the present invention, the
projections 66 contact the
top wall 24, providing rigidity and preventing any gravity induced sagging of the
filter unit 12 about the
bolt 50, thereby eliminating the problems associated with mounting the prior an filters horizontally.
As the
gasket 62 is retained within
groove 64, the need for an adhesive to permanently bond the
gasket 62 to the
end cap 56 is eliminated, greatly enhancing the replaceability of the
gasket 62. Preferably, a means is provided for retaining the
gasket 62 within the groove
In one embodiment of the invention, illustrated in FIG. 3, a gasket 62' is retained within the groove by angling the inner wall of each of the projections 66' towards the center of the groove. In this embodiment, the gasket 62' is preferably provided with a bevel cut so that the gasket 62' tapers away from, the end cap 56'. The pliable gasket 62' is compressed and inserted into the groove, where the gasket 62' expands to meet the inner walls of the projections 66'. The gasket 62' is thus retained within the groove by frictional forces.
In the alternate embodiment illustrated in FIG. 4, the gasket . .62.!. .Iadd.62" .Iaddend.is retained within the
groove 64 by forming the gasket . .62.!. .Iadd.62" .Iaddend.so at its inner diameter is somewhat less than the inner diameter of the
groove 64. The gasket . .62.!. .Iadd.62" .Iaddend.must be stretched outwardly to allow insertion of the same into the
groove 64. The gasket . .62.!. .Iadd.62" .Iaddend.thus exerts a force on the inner wall of the
inner projection 66, retaining the gasket . .62.!. .Iadd.62" .Iaddend.within the
groove 64.
Similarly, in a third embodiment illustrated in FIG. 5, the gasket . .62.!. .Iadd.62" .Iaddend.is retained within the
groove 64 by forming the gasket . .62.!. .Iadd.62" .Iaddend.so that its outer diameter is somewhat greater than the outer diameter of the
groove 64. The gasket . .62.!. .Iadd.62" .Iaddend.must be compressed inwardly to allow insertion of the same into the
groove 64. The gasket . .62.!. .Iadd.62" .Iaddend.exerts a force on the inner wall of the
outer projection 66, retaining the gasket . .62.!. .Iadd.62" .Iaddend.within the
groove 64.
In the most preferred embodiment, illustrated in FIGS. 6 and 7, the groove is provided with a plurality of altering inwardly-projecting
indentations 68 formed on the opposing inner walls of the
projections 66" forming the groove. The plurality of
indentations 68 frictionally retains the
gasket 62 within the groove. The
indentations 68 also facilitate insertion of the
gasket 62 into the groove .Iadd.in the
end cap 56" .Iaddend.by allowing the air beneath the
gasket 62 to escape as the
gasket 62 is inserted into the groove. The
indentations 68 are preferably struck from the side walls of the
projections 66".
In accordance with the provisions of the patent statues, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.