Pressure side integrated air filter and filtering networks for engines

A pressure side integrated air filter assembly for a turbocharged engine includes an air filter carrier which is designed and arranged to receive an air filter element and which is adapted to mount to the intake manifold of the turbocharged engine. The air filter carrier which receives an air filtering element is disposed within the intake manifold and the intake manifold cover serves as the air filter cover. A peripheral flange on the air filter carrier is used to support the air filter assembly by being clamped between the intake manifold cover and the intake manifold. This peripheral flange substitutes for the intake manifold gasket. The air filter carrier and the air filter element each have a trapezoidal shape in cross section as a way to conserve space within the intake manifold. The air filter element is a single panel of filtering media which is fan-folded with a first series of folds disposed adjacent the intake manifold cover and an alternating second series of folds disposed at the outlet side of the air filter carrier. The integrated air filter assembly is mounted within the intake manifold and may be used as a security filter with a cannister filter positioned upstream from the turbocharger or with a precleaner air filter disposed upstream from the turbocharger.

BACKGROUND OF THE INVENTION 
The present invention relates in general to vehicle air filters and to the 
overall theory of air filtration for an internal combustion engine. More 
specifically the present invention relates to high-efficiency air filters, 
air filters which are incorporated into the engine block and the use of a 
combination of filters in a filtering network to provide cleaner intake 
air to the engine. 
Traditionally, automotive air filters have been designed as separate, 
add-on components to the engine air intake system. One result or this 
design philosophy has been the evolution of cannister-type air filters. 
However, these air filters are bulky and must be utilized in combination 
with external connecting conduits involving several assembly steps as well 
as several components. The outcome is typically an air filter installation 
which is prone to leakage. Another potential problem is that these bulky, 
cannister filters may admit dust to the engine when the air intake system 
is being service. A still further potential problem for the manufacturer 
of the air filter is the integrity of the installation which will be 
performed by the purchaser--OEM. Since system responsibility rests with 
the OEM, the quality of each installation can vary and there is no fixed 
or standard quality level. 
The present invention addresses these concerns in a number of ways by the 
filter designs and filter system arrangements which are disclosed and 
described herein. The present invention provides a high-efficiency 
precleaner filter which may be arranged in alternative forms. Also 
included as part of the present invention is a barrier filter which is 
incorporated directly into the engine block (intake manifold) in order to 
trap any remaining dust which is not trapped by whatever filter 
arrangement may be installed upstream from the engine block. This 
integrated filter also helps to protect the engine from dust in any 
original or replacement air intake plumbing or components. 
Part of the theory embodied in the present invention as it relates to 
diesel engines can be explained in the following manner. Since diesel 
engines are turbocharged, the air on the pressure side of the turbocharger 
has a greater density, and thus a smaller filter can be used to achieve 
the same dust-holding capacity. It is a well established fact that 
reducing the "face velocity" of flow through a given area of filtering 
medium allows a higher dust holding capacity to be realized. The increased 
air density in effect reduces the velocity of flow through the medium and 
provides that benefit. Secondly, since the thermodynamic "work" associated 
with pumping a gas volume (assumed incompressible) across a restriction is 
equal to the volume times the restriction, then the maximum allowable 
restriction (termination restriction level) for a pressure side integrated 
air filter is larger since the volume of gas is smaller due to increased 
density. Specifically, assuming equal air temperatures, for equal "work" 
and hence engine performance, the termination restriction for a pressure 
side integrated air filter is equal to the conventional "upstream of 
turbo" termination restriction level (usually 25 in H.sub.2 O for turbo 
diesels) multiplied by the turbo boost ratio (usually around 2.5 for turbo 
diesels). Simply put, a filter on the pressure side of the turbocharger 
can be "plugged" to a higher degree since the pumping energy remains lower 
due to the lower volume flow. Consequently, a filter placed downstream of 
a turbocharger can hold more dust than a naturally-aspirated filter with 
the same pressure drop. Combining with filter with a suitable precleaner 
will significantly lengthen the service interval for the engine. Another 
advantage of an integrated filter system, such as that disclosed herein, 
is that it allows the engine manufacturer to carefully control the air 
filtration quality and this is expected to reduce warranty claims directed 
to dust which is ingested by the engine during servicing. 
The integrated air filter which is housed in the engine block (intake 
manifold) requires very little space due to its geometry and does not 
require any housing. When this integrated air filter is used as a primary 
air filter, an upstream, inertial precleaner (or similar precleaner) is 
needed to protect the turbocharger. However, this integrated air filter 
could simply be used as a safety filter without regard to what type of 
upstream filtration system is in place. In this approach, this "safety" 
filter would provide advantages to the end-user in terms of fail-safe 
engine protection. 
Improvement efforts for air filters and air filtration systems have been 
ongoing for a number of years. Some of these efforts have resulted in 
issued United States patents. A representative sample of such patents is 
listed below and while each may possess certain elements of novelty, as 
its time of issue, none are believed to be particularly close to the 
teachings of the present invention: 
______________________________________ 
U.S. Pat. No. 
Patentee Issue Date 
______________________________________ 
3,884,658 Roach May 20, 1975 
4,204,848 Schulmeister et al. 
May 27, 1980 
4,347,068 Cooper Aug. 31, 1982 
4,373,940 Petersen Feb. 15, 1983 
4,482,365 Roach Nov. 13, 1984 
4,673,503 Fujimoto Jun. 16, 1987 
4,702,756 Yajima Oct. 27, 1987 
5,125,940 Stanhope et al. 
Jun. 30, 1992 
______________________________________ 
SUMMARY OF THE INVENTION 
A pressure side integrated air filter assembly for a turbocharged engine 
which includes an intake manifold according to one embodiment of the 
present invention comprises an air filter carrier designed and arranged to 
mount to the intake manifold, a portion of the air filter carrier being 
disposed within the intake manifold and the air filter carrier including 
an exit aperture for the exit flow of filtered air, an air filter element 
having an inlet side and an outlet side and being loaded into the air 
filter carrier and positioned across the exit aperture and an air filter 
cover designed and arranged to mount to the intake manifold over the air 
filter element, the air filter cover having an air inlet aperture to 
introduce air into the air filter element. 
According to another embodiment of the present invention a filtering 
network is disclosed in combination with a turbocharged internal 
combustion engine. The engine includes a turbocharger and an intake 
manifold which is disposed in air flow communication with the 
turbocharger. The air filter network includes a precleaner air filter 
positioned upstream from the turbocharger and a pressure side air filter 
assembly disposed within the intake manifold and enclosed by an intake 
manifold cover. 
One subject of the present invention is to provide an improved pressure 
side integrated air filter assembly. 
Another object of the present invention is to provide an improved air 
filter network for a turbocharged internal combustion engine. 
Related objects and advantages of the present invention will be apparent 
from the following description.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
For the purposes of promoting an understanding of the principles of the 
invention, reference will now be made to the embodiment illustrated in the 
drawings and specific language will be used to describe the same. It will 
nevertheless be understood that no limitation of the scope of the 
invention is thereby intended, such alterations and further modifications 
in the illustrated device, and such further applications of the principles 
of the invention as illustrated therein being contemplated as would 
normally occur to one skilled in the art to which the invention relates. 
Referring to FIG. 1 there is illustrated a conventional engine air intake 
system 20 which represents the starting point for a discussion and 
explanation of the present invention. System 20 includes a conventional 
cannister air filter 21, turbocharger 22, charge air cooler 23 and intake 
manifold 24. Filter inlet 25 is connected to rubber bellows 26 which in 
turn seals to the hood inlet (not illustrated). Conduit 27 and elbows 28 
and 29 form the connection and air flow path from filter outlet 30 to the 
turbocharger 22. The incoming air to filter 21 has a density which is 
approximately 0.075 lb/ft.sup.3 (0.0047 Kg/m.sup.3). The maximum 
restriction at the outlet 30 is 25 inches of water and the charge air 
entering the intake manifold has a density which is approximately 0.177 
lb/ft.sup.3 (0.011 Kg/m.sup.3). As discussed, there may be some concern 
over sealing of the connections from the air filter 21 to the turbocharger 
22. The two elbows 28 and 29 each create two locations where sealing is 
critical. These four locations include the connection interfaces between 
outlet 30 and elbow 28, elbow 28 and conduit 27, conduit 27 and elbow 29 
and elbow 29 and turbocharger 22. 
Referring now to FIG. 2 there is illustrated a pressure side, integrated 
air filter system 34 according to one embodiment of the present invention. 
System 34 is similar in some respects to system 20 in that there is still 
a turbocharger 35, charge air cooler 36 and intake manifold 37. However, 
any truly substantive similarities end here. The differences include 
replacement of air filter 21 with precleaner 38 and integrating an air 
filter 39 into the intake manifold. Precleaner 38 may be arranged with an 
electrical scavenger blower 40 which is the embodiment illustrated in FIG. 
2 or with a sealed dust bin (see FIGS. 13 and 13A), or with a pressure 
driven ejector as illustrated in FIG. 5. 
System 34 includes bellows 41 and an outer sleeve 42 as part of precleaner 
38 which connects to the air intake duct 43 of turbocharger 35 for 
directly to the turbocharger. The density of the incoming air is not 
changed and the charge air density entering the intake manifold remains 
0.177 lb/ft.sup.3 (0.11 Kg/m.sup.3). A more detailed explanation of the 
structure and operation of a precleaner such as precleaner 38 will be 
provided hereinafter in connection with the discussion of FIGS. 12 and 
12A. Additionally, there is an alternative style of precleaner illustrated 
in FIGS. 13 and 13A and that will also be discussed as there are several 
options for the specific design and style of a precleaner as part of the 
filtering system according to the present invention. A more detailed 
explanation of the structure and operation of the pressure side integrated 
air filter 39 will also be provided hereinafter. 
Referring to FIG. 3 there is illustrated a pressure side, in-line air 
filter system 47 according to one embodiment of the present invention. 
System 47 is virtually identical to the present invention illustrated in 
FIG. 2 except that the integrated air filter 39 (of FIG. 2) has been 
removed from within the intake manifold 49 and replaced by in-line filter 
48. In those situations where pressure side filtering and/or safety 
filtering is designed, but where an integrated filter (installed into the 
intake manifold) is not desired, system 47 may be used. 
The pressure side in-line filter 48 is designed using a coiled or spiral 
wrapped corrugated filtering medium. The beginning configuration of the 
corrugated filtering medium 50 is illustrated in FIG. 3A as it is being 
coiled. Each inside channel 51 is sealed at one end along edge 52 while 
the opposite end of each channel remains open. The alternating troughs 53 
are open along edge 52 while the opposite end of each trough is sealed 
closed in the coiled configuration along edge 52a. In FIG. 3B the 
assembled in-line filter 48 is illustrated in greater detail. The air flow 
pattern is illustrated by the arrows wherein the inlet side of the coiled 
corrugated filtering medium corresponds to edge 52. The entering air flows 
into the open face of each trough 53 along edge 52. Since the alternating 
channels 51 are closed (by sealant or crimping) along edge 52, air is not 
allowed to flow in. However, along the opposite edge 52a the reverse 
configuration of what is open and what is closed is present and as 
indicated is just the opposite from edge 52. Along the opposite edge 52a 
the troughs are closed and the channels are open. As a consequence, the 
entering air flow is thereby force to flow through the filtering medium 
from the troughs to the adjacent channels. 
Referring to FIG. 4 there is illustrated a pressure side, integrated air 
filter system 57 according to a still further embodiment of the present 
invention. In system 57 a precleaner 54 is used upstream from the 
turbocharger 55. The charge air cooler 36 and intake manifold 37 conform 
generally with the structure and operation of those same components as 
illustrated in FIG. 2. An integrated air filter 56 is positioned within 
the intake manifold 37 as has been described in the context of FIG. 2. 
Referring to FIG. 5, the design of precleaner 54 involves the placement of 
a swirl vane arrangement 58 at the inlet 59 for intake air. Configuration 
64 which is attached to precleaner 54 is typically referred to as a 
pressure ejector nozzle with a venturi. The swirl vane arrangement 58 
incorporates 12 vanes each with a 43 degree exit angle. This creates a 
swirling air flow pattern with a clean air core which is routed through 
conduit 60 and out through outlet aperture 61 which is in direct flow 
communication with the inlet to the turbocharger 55 (see FIG. 4). While a 
specific swirl vane arrangement has been illustrated, a number of 
variations are possible and have been used successfully. 
Line 62, which may be oriented on either side of module 64a, is connected 
at one end 63 to the downstream side of the turbocharger 55 before the 
charge air cooler 36 and at the opposite end 62a to venturi module 64a. 
Line 62 has been placed on the left side of module 64a as opposed to the 
right side in FIG. 4 simply for drawing clarity. The venturi module in 
turn is connected to and become a part of the precleaner 54. Approximately 
one percent of the charge air bleeds off and is routed (by pressure 
difference) through line 62 to the venturi module 64a so as to create a 
venturi effect that draws off the larger particulate or "dirty" air which 
is swirled to and against the inside surface 65 of conduit 66 of 
precleaner 54. The collected particulate is disposed outside of conduit 60 
and downstream from the conduit inlet 67 and thus can be easily drawn off 
with the venturi module placed at that location. There is also little risk 
that the separated particulate can reenter the core of clean air due to 
the continuing swirling air flow. 
As illustrated in FIG. 4, a check valve 62b is placed in line 62 between 
module 64a and end 63. Check valve 62b is provided to prevent backflow 
during zero boost conditions. A zero boost condition would occur during a 
downhill run. 
Referring to FIG. 6, the design of integrated air filter 71 is illustrated. 
The drawing also includes a diagrammatical illustration of the air flow 
path through the filter and intake manifold 37. Air filter 71 (represented 
schematically in FIGS. 2 and 4 as reference items 39 and 56) represents 
the preferred embodiment of the present invention for the air filter which 
is to be integrated into the intake manifold. The orientation of FIG. 6 is 
turned end for end 180 degrees from the left to right flow direction which 
was used for FIGS. 1 through 4. 
The charge air enters the manifold cover 72 via inlet tube 73 (shown in 
broken line form). Manifold cover 72 doubles as an air filter cover. 
Filter 71 is mounted and sealed such that the entering air is forced to 
flow through the fan-folded filtering media 74. Enclosure 75 constitutes a 
filter carrier and the outer flange 76 is clamped beneath the manifold 
cover by a series of bold 77 which are threadedly received by the intake 
manifold. The peripheral flange 76 of the filter carrier (enclosure) 
replaces the manifold cover gasket. 
The air filter 72 as styled and configured in FIG. 6 has a trapezoidal 
shape (in cross section) as a means to conserve space and to fit within 
the space which is available within the intake manifold 37. A 
parallelogram shape could also be used for filter 71. With the illustrated 
trapezoidal shape (in cross section) the filtering media 74 is a single 
panel of material which has a first series of folds 74a adjacent cover 72 
and an opposite and alternating second series of folds 47b adjacent the 
rear wall 78 of carrier 75. 
The rear wall 78 is open or slotted to enable the filtered air to exit and 
flow to manifold aperture 79 which coincides with the intake port 
(passageway 80) disposed in head 81. The head 81, valve cover 82, valve 
83, piston 84 and rod 85 are each diagrammatically illustrated in broken 
line form since their design is not critical and since they do not 
comprise a part of the new invention. Passageway 86 is the oil rile and 
passageway 87 is the water jacket. 
One alternative to the design of the FIG. 6 filter 71 and the intake 
manifold 37 is to provide an air deflector at the rear of the air filter 
91 as is illustrated in FIG. 7. As illustrated, this air deflector 92 is 
integral with an extends up from lower edge 93 of filter carrier 
(enclosure 94) at an angle so as to not interfere with the flow of 
filtered air. While deflector 92 directs the exiting air flow in a more 
vertical path, one of the primary benefits of deflector 92 is as a heat 
shield. By providing a physical barrier in the manner illustrated by 
deflector 92, the exiting filtered air remains close to the filter 91 and 
spaced from the hotter portions of the intake manifold 37. The deflector 
92 also serves as a heat shield to help reduce and hopefully preclude any 
noticeable re-heating of the exiting air as can otherwise occur when the 
air is allowed to contact the block wall. 
One concern to be addressed with any integrated filter design which is 
installed into an enclosed space is the ease of removal and replacement 
with a new filter. Can maintenance time be reduced while still keeping the 
overall packaging concept simple and reliable? Ideally there would be a 
quick and convenient structural arrangement for opening the filter 
compartment of the intake manifold and removing the old filter. To this 
end four different packaging arrangement are illustrated in FIGS. 8 
through 11. 
Referring to FIG. 8 part of a typical intake manifold 98 and a 
representative or generic air filter 99 are illustrated. The filter 
compartment 100 is enclosed by cover 101. Cover 101 is hinged along one 
side edge 102 by pin 103. The cover 101 is notched to allow easy assembly 
of the cover as well as hinged movement. 
Along the opposite (upper) edge 104 of the cover a securing stud 105 is 
used in combination with latch 106. The latch is designed so as to pivot 
as illustrated in broken line form to a point which is beyond or 
"over-center" so that it will stay in the stowed position. A notch 107 in 
stud 105 allows the latch to slide off or out which in turn permits 
removal of cover 101. A single angular gasket 108 seals both the filter 99 
and the cover 101. 
Referring to FIG. 9 there is illustrated a representative intake manifold 
111 which includes a filter compartment 11, a filter carrier 113 and a 
cover conduit 114. An air filter 115 is assembled into the filter carrier 
113 by loading it into the interior-most end 116 of carrier 113 where an 
inwardly-directed lip 117 is used as an abutment surface for the filter. A 
silicone adhesive 118 is applied between the outer end of the filter and 
the carrier 113. The cover conduit is assembled to the carrier an in turn 
to the intake manifold by a series of threaded studs 119 which are 
anchored into the intake manifold. These studs provide a simple and quick 
alignment for the assembled air filter 115 as well as for cover conduit 
114. Hex nuts 120 are used to complete the assembly. 
Referring to FIG. 10 there is illustrated a representative intake manifold 
124 which includes a filter compartment 125 and cover 126. An air filter 
127 is assembled into the filter compartment 125 and an annular gasket 128 
is used to establish the seal between the air filter, the intake manifold 
and the cover. 
There are spaced locations in the intake manifold 124 surrounding the air 
filter 127 which are internally threaded at 129. Corresponding threaded 
bolts 130, each with an enlarged handle portion 131, extend through 
bracket 132 and are threaded into the internally threaded holes at 129. As 
these bolts are tightened the bracket is drawn up against the cover 
thereby holding the cover and filter in position. 
In the FIG. 11 arrangement the studs 136 are similar to what was 
illustrated in the FIG. 9 arrangement for studs 119. Wing nuts 137 replace 
the previously used bolt 130. In virtually all other respects the FIG. 10 
and 11 arrangements are the same. 
In FIGS. 12 and 12A and in FIGS. 13 and 13A a couple of specific designs 
are illustrated for a suitable precleaner which may be used in the system 
configurations of FIGS. 2 and 3. Although similar in a number of respects, 
precleaner 140 as illustrated in FIGS. 12 and 12A includes a scavenger 
blower 141 which is driven by a 12 volt DC motor 142. In contrast, 
precleaner 143 as illustrated in FIGS. 13 and 13A includes a sealed dust 
bin 144 disposed below the array of vortex tubes 145. 
With reference more specifically to FIGS. 12 and 12A, precleaner 14 
includes an inlet 150, outlet 151, water separation/flow distribution 
screen 152 and a panel of acoustical foam 153 which is bonded to the outer 
wall of the precleaner. Disposed between inlet 150 and outlet 151 and 
above the scavenger blower 141 is an array 154 of evenly spaced, vortex 
tubes 155. A total of 132 vortex tubes 155 are positioned in the array 154 
and each vortex tube has a first end 159 mounted into inlet plate 160 and 
an opposite, second end 161 mounted into outlet plate 162. The actual 
number of vortexing tubes 155 will vary with engine size. 
With reference more specifically to FIGS. 13 and 13A, precleaner 143 
includes an inlet 170, outlet 171, water separation/flow distribution 
screen 172 and a panel of acoustical foam 173 bonded to the inside surface 
of the outer wall of the precleaner. Disposed between the inlet 170 and 
outlet 171 above the dust bin 144 is an array 174 of evenly spaced, vortex 
tubes 145. A total of 78 vortex tubes 145 are positioned in the array 174 
and each tube has a first end 179 mounted into inlet plate 180 and an 
opposite, second end 181 mounted into outlet plate 182. Here again, the 
actual number of vortex tubes 145 will vary with engine size. 
Vortex tubes 155 and 145 are each variations of a basic vortex tube 
inertial separator. Such vortex tubes rely strictly on inertial separation 
of particulate in a spinning (vortex) flowstream of gas. The two different 
designs are really not much different (other than in size) from the 
"single-tube" precleaner shown in FIG. 6. The gas enters the front end of 
the tube and encounters the helical swirl vanes, item 163 in FIGS. 12 and 
12A and item 183 in FIGS. 13 and 13A, which impart a swirl to the gas 
flow. The particles then migrate toward the wall and are exhausted through 
a dust outlet slot or port cut in the tube wall. The particle depleted 
core of swirling air is stripped off by the smaller concentric diameter 
sleeve within the tube body. The smaller concentric diameter sleeve is 
item 184 in FIGS. 12 and item 185 in FIGS. 13. 
The basic difference between the two vortex tube designs is primarily 
diameter, but there are some additional subtle design differences such a 
the slightly flared body of the vortex tubes shown in FIG. 13. The 
operation of the larger slightly flared design of FIG. 13 has better 
performance when zero scavenge flow is used as with a sealed dust bin. 
The primary advantage of the multi-tube design (array) over the single-tube 
design shown in FIG. 5 is of increased separation efficiency. For a given 
vortex tube air inlet velocity (and corresponding restriction), the 
inertial separative force on the particles is inversely proportional to 
the tube radius. Therefore, using many small tubes rather than one large 
tube yields higher efficiency and better protection for the turbocharger 
as well as longer air filter life. 
While the invention has been illustrated and described in detail in the 
drawings and foregoing description, the same is to be considered as 
illustrative and not restrictive in character, it being understood that 
only the preferred embodiment has been shown and described and that all 
changes and modifications that come within the spirit of the invention are 
desired to be protected.