A spin-on type filter assembly for lubricating oil includes a cast aluminum housing which contains a replaceable annular filter element. The filter element is resiliently retained in the housing by compressing a gasket thereon with a threaded end cap which closes one end of the housing. The housing includes a unitary front end wall with a plurality of inlet ports surrounding an axially positioned outlet port. In order to provide a secure coupling with the engine, an externally and internally threaded steel stud is threadably mounted in the outlet port for threadably coupling with the engine.

FIELD OF THE INVENTION 
The present invention relates to rebuildable spin-on filters. More 
particularly, the present invention relates to rebuildable spin-on filters 
for lubricating oil. 
BACKGROUND OF THE INVENTION 
Most internal combustion engines utilized in automotive vehicles and the 
like are lubricated by circulating lubricating oil. The lubricating oil 
entrains solid contaminant particles resulting from engine wear, dirt 
entering the engine during operation and products of combustion. In order 
to prolong engine life, it is necessary to remove these contaminant 
particles. This is done by circulating the lubricating oil through a 
filter medium which in most cases is in the form of corrugated filter 
paper retained in a metal canister. As time passes, the filter paper 
becomes clogged. Engine manufacturers strongly suggest that the filter 
assembly, which includes the filter paper medium, be replaced after 
several thousand miles. The used filter assemblies must then be disposed 
of. Since the filter assemblies necessarily contain oil trapped in both 
the filter canister and in the filter medium, each used filter assembly is 
a potential source of pollution if disposed of in a conventional manner by 
deposit in a land fill. Since oil filters are usually replaced at least 
two to three times per year, used oil filters placed in land fills can 
contaminant ground water. 
In order to protect the ground water, a number of states have now passed 
ordinances prohibiting disposing of used, canister-type, lubricating oil 
filters in landfills. This development has resulted in a need to 
reconfigure oil filters to accommodate these new regulations. 
SUMMARY OF THE INVENTION 
It is a feature of the present invention to provide an oil filter assembly 
which facilitates disposal of used oil filters while minimizing the 
environmental impact of such disposal. 
In view of this feature and other features, the present invention is 
directed to a filter assembly useful for filtering lubricating oil 
circulated through internal combustion engines wherein the filter assembly 
includes a housing formed about an axis. The housing has a front end and a 
rear end with an end wall at the front end extending radially with respect 
to the axis. A plurality of inlet ports are positioned in the end wall and 
communicate with the interior of the housing. The inlet ports are 
distributed around the axis of the housing in spaced relation to the axis. 
An outlet port in the end wall is aligned with the axis of the housing and 
a removable end cap is secured to the rear end of the housing. An annular 
filter element is retained within the housing and has a hollow core 
surrounded by an annular filter medium with an outer cylindrical surface 
and an inner cylindrical surface disposed between front and rear end 
supports. The annular filter element is removably disposed within the 
housing with the inner surface of the filter medium isolated from the 
outer surface, wherein fluid flowing into the inlet ports passes through 
the filter medium and out through the outlet port. Since the filter 
element structure is readily separable from the housing, it can be 
separately disposed of, significantly reducing the amount of used 
lubricating oil which is disposed of by being trapped in or with the 
filter element.

DETAILED DESCRIPTION 
Referring now to FIG. 1, there is shown a first embodiment of a rebuildable 
spin-on filter assembly, filter assembly 10, configured in accordance with 
the principles of the present invention for use with internal combustion 
engines (not shown). The filter assembly 10 includes an annular filter 
element 11 retained within an aluminum housing 13 which is concentric with 
an axis 14. The filter element 11 includes a pleated filter media 12 
retained between a radially open front end support 15 and a radially 
closed rear end support 16, which supports extend radially from a unitary 
annular core support 18 having circular holes 20 therethrough which 
communicate with a hollow core 21. In a preferred embodiment, the filter 
medium 12 is configured of pleated paper having exterior and interior 
surfaces with the interior surfaces being in communication with the holes 
20 in the core support 18 and the exterior surfaces being in communication 
with a space 22 provided in the assembly 10. As will be explained further 
hereinafter, oil in the space 22 flows through the pleated filter media 12 
and the holes 20 in the core support 18 to emerge in a filtered state in 
the hollow core 21. 
Referring now to FIG. 2, it is seen that the filter element 11 is a 
discrete, integral unit which is separable from the filter assembly 10. In 
accordance with the principles of the present invention, when the oil in 
the engine is changed, the filter element 11 is disposed of separately 
instead of being disposed of with the entire assembly 10. Since the filter 
element 11 has a hollow core 21, oil in the hollow core 12 is separated 
from the filter element when the filter element is removed from the 
assembly. Accordingly, the only oil remaining is the residue of oil 
coating the surfaces of the filter element 11 and the residue remaining 
within the material forming the pleats of the filter media 12. 
A suggested method of disposing of the used filter elements 11 is 
incineration the filter elements at very high temperatures in order to 
minimize air pollution and then to dispose of the ash in a conventional 
environmentally safe manner. 
Another method might be to wash the filter elements with detergent solution 
to separate the oil therefrom and then to separate the oil from the 
solution for environmentally safe disposal. The cleaned filter elements 11 
are then disposed of, or recycled, in an environmentally safe manner. 
In order to facilitate separation of the filter element 11 from the 
assembly 10, the filter element is slidably received within the aluminum 
housing 13 which is used in place of the conventional disposable canister. 
The housing 13 comprises a first end 31 and a second end 32. The structure 
of the first end 31 is best seen in FIGS. 1 and 3 wherein a unitary end 
wall 33 includes a first annular groove 34 (FIG. 1) and a second annular 
groove 35 (FIG. 1). The annular groove 34 seats a first annular gasket 36 
while the second annular groove 35 seats a second annular gasket 38 which 
is spaced from and concentric with the first annular groove. A recessed 
portion 39 formed in the end wall interiorly of the gaskets 36 and 38 
includes six inlet ports 40 and an internally threaded outlet port 42. 
The internally threaded outlet port 42 is defined by either the steel 
mounting stud 50 of FIG. 4 or the steel mounting stud 52 of FIG. 5 which 
differ slightly from one another in that the mounting stud 50 has a 
shoulder 54 thereon. The studs 50 and 52 have internal threads 56 and 58, 
respectively, for threading with an inlet tube of the engine (not shown) 
and external threads 60 and 62 for threading with internal threads 64 (see 
FIG. 1) in the end wall 33. 
As is seen in FIG. 6, the housing 13 includes a barrel portion 70 which is 
unitary with and extends from the end wall 33. The barrel portion 70 
defines the space 22 into which oil flows from the input ports 40. The 
second end of the cylindrical housing 32 includes internal threads 72 and 
a groove 74 with an axially facing gasket 76. 
Referring now primarily to FIGS. 7 and 8, a threaded end cap 80 having 
radially extending flange 82 and a plug portion 84 which is externally 
threaded with threads 86, threads into the rear end 32 of the housing 13 
to close and seal the rear end of the housing. In order to facilitate 
attaching and removing the end cap 80, a square recess 88 is formed 
through the outer surface 90 of the end cap. The recess 88 receives 
non-rotatably the head of a tool (not shown) so that the end cap 80 may be 
rotated in order to be screwed into or unscrewed from the barrel portion 
70 of the housing 13. The outer surface 90 and the inner surface 91 of the 
end cap 80 are preferably substantially planar in a radial direction with 
respect to the axis 14 of the filter assembly 10, thus configuring the end 
cap as a disk and minimizing the axial length of the filter assembly. 
Preferably the barrel portion 70 and end cap 80 are both fabricated by 
being cast of aluminum while the mounting studs 50 and 52, which couple 
directly with the engine are made of steel. 
Referring again to FIG. 1, in order to facilitate retaining the filter 
element 11 tightly within the barrel portion 70 of the housing 13, an 
annular spacing gasket 100 of resilient material is disposed between the 
rear end plate 16 of the filter element and the end cap 80. The spacing 
gasket 100 has a radial width greater than its axial thicknesses. A coil 
spring 102 is disposed within a spring steel up-front bypass valve 104. 
The up-front bypass valve 104 is configured to allow the filter element 11 
to be bypassed if the filter media 12 becomes clogged. The up-front bypass 
valve 104 bears against a molded anti-drainback valve 106 which closes to 
seal the inlet ports 40 when the engine (not shown) on which the filter 
assembly 10 is mounted is not running. 
In the present embodiment, up-front bypass valve 104 and anti-drainback 
valve 106 are components which are slidably received in the housing 13 and 
are slidably removed from the housing so as to be disposed of when the 
filter element 11 is changed. These retaining elements are furnished as a 
kit and are replaced each time the filter assembly 10 is "rebuilt" with a 
fresh filter element 11. Preferably, the spacing gasket 100 is integral 
with the filter element 11 and is disposed of and introduced each time the 
filter element 11 is changed. 
When it is necessary to change the filter element 11, lubricating oil 
within the housing 13 (including the oil in hollow core 21) is drained 
into a container (not shown) upon removing the rear end cap 80. 
Consequently, the bulk of the oil within the oil filter assembly 10 is 
recycled in the same manner as oil drained from the engine block. 
Accordingly, the only oil which must be disposed of by an approach other 
than the usual recycling, is residual oil coating the filter element 11 
and suspended in the material of the filter media 12. 
Referring now to FIGS. 9 and 10, there is shown a second embodiment, filter 
assembly 110, of the invention which is similar to the first embodiment. 
The second embodiment 110 differs from the first embodiment 10 of FIG. 1 
in that the bypass valve 120 of the second embodiment 110 is disposed 
between the threaded end cap 80 and a coil spring 122 instead of between 
the filter element 11' and an anti-drainback valve, as is the case with 
the bypass valve 104 of FIG. 1. In the embodiment of FIGS. 9 and 10, the 
spacing gasket 100 is not used because the assembly is biased together 
with coil spring 122. 
As is seen in FIG. 10, the bypass valve 120 is a separate component with an 
internal coil spring 124 which biases a valve plate 126 to its closed 
position. When pressure in the housing 10 exceeds a predetermined level, 
the force exerted by the spring 124 is exceeded pushing the valve plate to 
an open position so that the lubricating oil flows through the bypass 
valve into the hollow core 21' of the filter element 11'. The bypass valve 
120 and coil spring 122 are separate from the filter element 11 so that 
when the filter element is disposed of, the bypass valve 120, coil spring 
122 and filter element (which includes the oil soaked filter media 12) are 
disposed of (or perhaps recycled) separately. 
In the embodiment of FIG. 9, the filter element 11' has an end plate 16' 
which is annular so that the bypass valve 120 seats in the hollow core 21' 
of the filter element. The force of the coil spring 122 bearing on the 
bypass valve 120 urges the filter element 11' against an annular filter 
element support 128, which in turn seats against the end wall 33 at the 
first end 31 of the aluminum housing 13. The aluminum housing 13 is 
therefore useable with either the first embodiment of the invention (FIG. 
1) or the second embodiment of the invention 110 (FIG. 9). 
From the foregoing description, one skilled in the art can easily ascertain 
the essential characteristics of this invention, and without departing 
from the spirit and scope thereof, can make various changes and 
modifications of the invention to adapt it to various usages and 
conditions.