Integrated and separable EGR distribution manifold

An exhaust gas recirculation (EGR) manifold received within an intake manifold. The EGR manifold includes a plurality of holes for delivery of recirculated exhaust gas within the flowpath of the intake manifold. Both linear and round shapes are contemplated for the EGR manifold.

BACKGROUND OF THE INVENTION 
The present invention relates to improvements in exhaust gas recirculation 
manifolds for internal combustion engines, although some applications may 
be outside of this field. 
Since the mid 1970s, it has been appreciated that the recirculation of 
exhaust gas into the inducted air of the intake manifold produces certain 
benefits in terms of reduced emissions. Typically, a small amount of 
exhaust gas is taken from the exhaust manifold, passed in appropriate 
plumbing to a controlling component such as a valve, and then introduced 
through a fitting into the intake manifold. Various designs relate to this 
area, including: 
______________________________________ 
Patent No. Patentee Issue Date 
______________________________________ 
5,490,488 Aversa et al. 2/13/96 
4,870,941 Hisatomi 10/3/89 
4,072,133 McWhirter 2/7/78 
5,490,488 Aversa et al. 2/13/96 
3,717,130 Thornburgh 2/20/73 
3,717,131 Chana et al. 2/20/73 
5,492,104 Elder et al. 2/20/96 
5,609,144 Seizew et al. 3/11/97 
3,892,026 Thornburgh 7/1/75 
5,425,347 Zinke, II 6/20/95 
5,542,711 Vaudry 8/6/96 
5,329,912 Matsumoto et al. 
7/19/94 
4,609,009 Tisone 9/2/86 
2,034,144 Lauret 3/17/86 
5,427,080 Maeda et al. 6/27/95 
4,276,865 Hamai 7/7/81 
5,474,102 Lopez 12/12/95 
______________________________________ 
Many of these designs tend to produce less than adequate distribution of 
recirculated exhaust gas among multiple cylinders, especially when there 
is a single entry point for the recirculated exhaust gas, or when the 
recirculated exhaust gas is cooled or introduced in large flow rates. 
Cooling of the exhaust gas results in another problem of condensation of 
an acidic and corrosive mixture. 
What is needed is an improved exhaust gas recirculation (EGR) manifold, 
which the present invention proposes in a novel and unobvious way. 
SUMMARY OF THE INVENTION 
One aspect of the present invention provides an apparatus for an internal 
combustion engine comprising an intake manifold and a removable exhaust 
gas recirculation manifold. The intake manifold includes a cavity for 
receiving the exhaust gas recirculation manifold. The exhaust gas 
recirculation (EGR) manifold is insertable in the cavity of the intake 
manifold. The EGR manifold defines a plurality of holes for delivery of 
exhaust gas to the intake manifold. In another aspect of the present 
invention the EGR manifold is removable from the intake manifold without 
the need to detach the intake manifold from the engine. 
One object of the present invention is to provide an improved EGR manifold 
for an internal combustion engine. Related objects of the present 
invention will be apparent from the Description of the Preferred 
Embodiment.

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 embodiments 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. 
FIG. 1 is a cross sectional, front elevational view of an internal 
combustion engine incorporating a first embodiment of the present 
invention. A cast intake manifold 20 is shown attached through attachment 
boss 22 to a cylinder head 24 of the engine. Head 24 is attached to an 
engine block 26 that includes one or more cylinders 27. A piston assembly 
28 is located in each cylinder 27. Also attached to head 24 is exhaust 
manifold 30. Intake valve 32 and exhaust valve 34 permit supply and 
removal respectively, of a gaseous mixture into cylinder 27. 
Intake manifold 20 incorporates an inlet 36 through which inducted air is 
provided. This mixture flows into internal flowpath 38 of manifold 20 and 
into intake port 40 when intake valve 32 is open. The mixture is combusted 
within cylinder 27, and flows as exhaust gas into exhaust port 41 and into 
exhaust manifold 30 when exhaust valve 34 is open. A portion of this 
exhaust gas is provided in a manner not shown to a separable and removable 
exhaust gas recirculation (EGR) manifold 42 received within first cavity 
44a of intake manifold boss 46, providing recirculated exhaust gas for 
mixing with the inducted air within flowpath 38. 
FIG. 2A is a side elevational view of the exhaust gas recirculation 
manifold of the first embodiment of the present invention. EGR manifold 42 
includes a hollow, generally cylindrical body 48 defining internal volume 
49 and incorporating a plurality of outlet holes 50. Exhaust gas flows 
into internal volume 49 which is in fluid communication with delivery 
holes 50. EGR manifold 42 incorporates flange 52 which defines inlet 54 of 
body 48, as shown in FIG. 2B. A pair of holes 56a in flange 52 are useful 
for fastening of EGR manifold 42 to intake manifold 20. End 53 of EGR 
manifold 42 incorporates a second inlet 55 that is in fluid communication 
with internal volume 49. Recirculated exhaust gas generally flows as 
indicated by arrow 57 (See FIG. 1). 
FIG. 3A is a top plan view of the FIG. 1 engine as taken along line 3A--3A 
in FIG. 1. The assembly includes EGR manifold 42 which has been inserted 
within intake manifold 20, with a first supply of exhaust gas delivered 
via conduit 62 and a second supply of exhaust gas delivered via conduit 64 
to different ends of intake manifold 20. First conduit 62 is attached to a 
flange boss 58 of manifold 20 through flange 52 of EGR manifold 42, and is 
in fluid communication with inlet 54. The second conduit 64 is attached to 
another flange boss 58 of manifold 20 through flange fitting 66 and is in 
fluid communication with inlet 55. The present invention is useful for 
exhaust gas recirculation systems in which one of the supply conduits 62 
or 64 provides exhaust gas that is essentially uncooled, and the other 
supply provides exhaust gas that is cooled through a heat exchanger (not 
shown). The cooled supply is typically at least 100 degrees Fahrenheit 
cooler than the uncooled supply. 
The present invention also contemplates an alternative intake manifold 
assembly which incorporates EGR manifold 42' in place of EGR manifold 42 
as shown in FIG. 3B. EGR manifold 42' has a single inlet 54 for exhaust 
gas, with end 53' being closed. The present invention contemplates that 
single inlet 52' can be in fluid communication with a single exhaust gas 
supply conduit 62 or 64, or as another alternative, single inlet 52' can 
be in fluid communication with a controlling device such as a valve that 
can alternately provide exhaust gas from either supply conduit 62 or 64. 
FIG. 4 is a side elevational view of the FIG. 3 assembly as taken along 
line 4--4 in FIG. 3A. EGR manifold 42 is supported by flange bosses 58 and 
received within cavities 44a and 44b of support bosses 46a and 46b, 
respectively, of intake manifold 20. It is preferable that support bosses 
46a and 46b be cast integrally into intake manifold 20, although 
separately attachable support bosses are within the scope of the present 
invention. Flange bosses 58 are of a conventional two fastener variety, 
though the present invention contemplates other methods of supporting EGR 
manifold 42. For example, one or more support bosses 46 could support 
manifold 42 along its length and intermediate of its ends. 
It is preferable but not necessary that the means for supporting manifold 
42 be compatible with the casting of intake manifold 20 in a casting tool 
that has received within it the EGR manifold prior to casting. It is 
preferable that the means for supporting manifold 42 allow for 
differential thermal growth between manifolds 42 and 20. The present 
invention contemplates fabrication of an exhaust gas recirculation 
manifold that is fabricated from a material different than the material of 
the intake manifold. In addition, the EGR manifold may be at a temperature 
different than the intake manifold. The difference in materials and 
temperatures may result in one manifold expanding or contracting a 
different amount than the other. Those of ordinary skill in the art 
understand various attachment methods for accommodating differential 
thermal growth. 
FIG. 5 is an end elevational view of the FIG. 3 assembly as taken along 
line 5--5 in FIG. 3A. A flange boss 58 is cast integrally into intake 
manifold 20. The surface of flange boss 58 is generally flat. A pair of 
blind fastener holes 59a located within boss 58 are generally aligned with 
holes 56a of flange 52. The surface of flange boss 58 is generally 
perpendicular to cavity 44a which receives one end of EGR manifold 42. 
FIG. 6A is a cross sectional view of a portion of the FIG. 3A assembly as 
taken along line 6A--6A in FIG. 3A. FIG. 6B is an exploded view of the 
portion of the FIG. 3A assembly shown in FIG. 6A. A flange fitting 66 is 
shown in contact with intake manifold 20. Fitting 66 includes a flange 
generally in the shape of boss 58. Fitting 66 also includes a short 
cylindrical section 67 received within second cavity 44b. End 53 of EGR 
manifold 42 slidably fits within the inner diameter of section 67. End 53 
is supported by cavity 44b through section 67. Differential thermal growth 
between intake manifold 20 and EGR manifold 42 is accommodated by sliding 
of end 53 within section 67. Second supply of exhaust gas 64 is attached 
to boss 58 through flange fitting 66. Exhaust gas is thus presented to 
second inlet 55 of EGR manifold 42. Alternative EGR manifold 42' includes 
a boss 46b' with a blind cylindrical cavity 44b' for slidably supporting 
closed end 53' as shown in FIG. 6C. 
FIGS. 7A and 7B are cross sectional views of FIG. 1 taken along line 7--7. 
FIG. 7A depicts alternative EGR manifold 42a inserted into intake manifold 
20, and FIG. 7B depicts alternative EGR manifold 42b inserted into intake 
manifold 20. FIGS. 7A and 7B show the present invention as applied to an 
in-line 6-cylinder internal combustion engine with 2 intake valves and 2 
exhaust valves per cylinder. The engine of FIG. 7A includes siamesed 
intake ports 40a-c, whereas the engine of FIG. 7B includes separate intake 
ports 40u-z for each cylinder. One skilled in the art will appreciate that 
the present invention is also applicable to engines with a different 
number of cylinders or valves per cylinder. Also, the present invention is 
applicable to engines other than in-line engines, including for example 
V-type engines. 
EGR manifold 42a in FIG. 7A includes an arrangement of EGR delivery holes 
50 in groupings 51a, 51b, and 51c. These groupings 51a, 51b, and 51c are 
arranged to flow predetermined proportions of exhaust gas into intake 
ports 40a, 40b, and 40c. Each grouping includes a number of delivery holes 
50 equal to or greater than the number of intake valves 32 at the 
respective intake port. 
EGR manifold 42b in FIG. 7B includes an arrangement of EGR delivery holes 
50 in groupings 51u, 51v, 51w, 51x, 51y, and 51z. These groupings 51u, 
51v, 51w, 51x, 51y, and 51z are arranged to flow predetermined proportions 
of exhaust gas into intake ports 40u, 40v, 40w, 40x, 40y, and 40z. Each 
grouping includes a number of delivery holes 50 equal to or greater than 
the number of intake valves 32 at the respective intake port. 
One of ordinary skill in the art will recognize that the predetermined flow 
of exhaust gas into intake ports 40 may be achieved with either less than 
or more than one hole 50 per intake valve. In addition, delivery holes 50 
in EGR manifolds 42, 42a, or 42b need not be equidistant or equal in size. 
One skilled in the art will appreciate that knowledge of the optimum 
placement and size of delivery holes 50 or groupings 51 may require use of 
computational fluid dynamics (CFD) or routine experimentation. For 
example, it may be advantageous to place some of delivery holes 50 near 
areas of high local air velocity within flowpath 38 so as to expose hole 
50 to low static pressure. One skilled in the art will also recognize that 
alternative manifolds 42a and 42b are compatible with the single source 
concept of alternative manifold 42'. 
FIG. 8 is a cross sectional front elevational view of an internal 
combustion engine incorporating a second embodiment of the present 
invention. It is understood that usage of numbers that are the same as 
numbers used to describe the first embodiment denote a feature or element 
that is substantially the same. A separable exhaust gas recirculation 
manifold 142 is shown accommodated within support boss 146 of intake 
manifold 120. Support 146 defines a cavity 144 proximate to intake 
manifold inlet 136. Exhaust gas recirculation manifold 142 is received 
within cavity 144 of support 146. Recirculation manifold 142, inlet 136, 
and boss 146 are generally round in shape. 
Exhaust gas recirculation manifold 142 include an outer wall 147 and an 
inner wall 151 which form between them annular volume 149. Exhaust gas is 
provided from exhaust manifold 30 to volume 149. This exhaust gas is 
recirculated into flowpath 138 of intake manifold 120 through a plurality 
of delivery holes 150 in wall 151. 
FIG. 9 is a side elevational view of the FIG. 8 engine including an EGR 
manifold as taken along line 9--9 in FIG. 8. Recirculation manifold 142 is 
retained atop intake manifold 120 in a manner not shown but obvious to 
those of ordinary skill in the art. For example, a bolted or clamped 
retention method can be used. Recirculation manifold 142 incorporates a 
flange fitting 152 which is in fluid communication with annular volume 149 
through tubular connection 159. A first supply of exhaust gas via conduit 
62 is provided to inlet 154 of flange 152. 
FIG. 10 is a cross sectional view of the FIG. 9 EGR manifold as taken along 
line 10--10. Exhaust gas supply conduit 62 is in fluid communication with 
inlet 154 of EGR manifold 142. Recirculated exhaust gas flows into inlet 
154, into annular volume 149, and into flowpath 138 through delivery holes 
150 as depicted generally by arrow 157. 
FIG. 11 is a view similar to that of FIG. 10 showing an alternate EGR 
manifold. EGR manifold 142' is similar to manifold 142, except that 
manifold 142' also incorporates a second inlet 155 which is in fluid 
communication with second supply of exhaust gas via conduit 64. 
Recirculation manifold 142 is suitable for internal combustion engines 
using two different supplies of exhaust gas for recirculation into 
flowpath 138. 
Delivery holes 150 are sized and located to provide a predetermined flow of 
exhaust gas into each intake port 40. One of ordinary skill in the art 
will recognize that the predetermined flow of exhaust gas into intake 
ports 40 may be achieved with an arrangement of delivery holes 150 that 
are not equidistant or equal in size. One skilled in the art will 
appreciate that knowledge of the optimum placement and size of delivery 
holes 150 in wall 151 may require use of computational fluid dynamics 
(CFD) or routine experimentation. In addition, delivery holes 50 and 150 
can be non circular openings. It may also be helpful to incorporate a 
feature that promotes mixing of the recirculated exhaust gas and the 
inducted air, such as a boundary layer trip downstream of holes 150. One 
of ordinary skill in the art will also recognize that EGR manifolds 142 
and 142' are applicable to a variety of types of internal combustion 
engines, including for example both in-line and V-type. 
The present invention includes apparatus and methods for providing a 
predetermined distribution of recirculated exhaust gas to the inducted air 
of an internal combustion engine by a separable EGR manifold integrated 
into the intake manifold. It is well known in the art that providing 
recirculated exhaust gas to the inducted air results in lower peak 
combustion temperature, with a subsequent reduction in the formation of 
nitrous oxides during combustion. It is also appreciated in the art that 
it may be advantageous under some conditions to cool the recirculated 
exhaust gas prior to mixing with the inducted air. However, the present 
invention includes the discovery that it is difficult to achieve good 
mixing of cooled recirculated exhaust gas with the charge of inducted air 
in the intake manifold. For example, if the cooled recirculated exhaust 
gas is introduced to the intake manifold at a single location, the cooled 
exhaust gas shows an affinity for the walls of the intake manifold and 
tends to stay near the walls. In this example of single point introduction 
of cooled exhaust gas there is a maldistribution of the recirculated 
exhaust gas among the various cylinders, with some cylinders receiving 
other than the predetermined percentage of exhaust gas. 
This problem of maldistribution may be worse in a diesel engine as compared 
to a spark ignition engine. A diesel engine typically has a higher 
pressure in the intake manifold than a spark ignition engine because the 
diesel engine operates in an unthrottled state. Because the recirculated 
exhaust gas flows as a result of a driving pressure differential between 
the recirculation manifold and the intake manifold, the higher intake 
manifold pressures of a diesel engine decreases this driving pressure 
differential and cause the recirculated exhaust gas to exit the 
recirculation manifold at lower velocities. The low velocity of the 
recirculated exhaust gas does not adequately discourage the affinity of 
the cooled exhaust gas for the walls of the intake manifold. 
The problem of a low driving pressure differential between the 
recirculation manifold and the intake manifold is further heightened by 
the use of a turbocharger. A turbocharger increases the pressure within 
the intake manifold and can result in a reversal of the driving pressure 
differential, such that the intake charge could flow into the 
recirculation manifold. The driving pressure differential can be restored 
such that recirculated exhaust gas flows into the intake manifold by the 
use of a separate pump to increase the pressure of the recirculated 
exhaust gas or by the use of a smaller turbine for the turbocharger, such 
that the pressure in exhaust manifold 30 increases. The present invention 
is useful with both an exhaust gas pump and also with a smaller turbine 
for a turbocharger. 
It is further appreciated within the art that cooling of recirculated 
exhaust gas results in creation of a corrosive medium. For example, water 
vapor within the exhaust gas condenses to liquid water if cooled 
sufficiently. This liquid water combines with other gases in the exhaust 
gas, such as sulphur dioxide, to form corrosive compounds such as 
sulphuric acid. The exhaust gas recirculation manifold should be capable 
of operation after repeated exposure to these corrosive mixtures. With the 
present invention, it is preferable that EGR manifolds 42, 42', 42a, 42b, 
142, and 142' be fabricated from a relatively inert material, such as a 
corrosion resistant stainless steel. 
Construction of EGR manifold 42, or any of its' alternatives, may be 
constructed from a corrosion resistant material with a relatively high 
melting point permits economical fabrication of the EGR manifold within 
the intake manifold. For example, body 48 can be fabricated from tubing 
stock or rolled from sheet stock. Flange 52 can be welded or otherwise 
suitably attached to body 48. Intake manifold 20 is typically fabricated 
from a castable, lower melting point material, such as an organic compound 
or aluminum. Since the melting point of such intake manifold materials is 
sufficiently lower than the melting point of the EGR manifold material, 
the finished assembly 42 can optionally be inserted into the casting tool 
used to cast intake manifold 20. Intake manifold 20 can be cast around the 
finished EGR manifold 42. A suitable material for EGR manifolds 42 and its 
alternatives is 304 stainless steel, as an example only. Examples of 
suitable materials for intake manifold 20 and 120 include A380 aluminum, 
AZ91E or AZ91D magnesium, 6/6 nylon, and Amodel A-1133. 
In addition, it is preferable that the recirculation manifold be removable 
and separable from the internal combustion engine with minimal removal of 
other components. The present invention contemplates removal of the 
exhaust gas recirculation manifolds 42 and 142 and their alternatives 
without the need to remove the intake manifold from the engine, such as 
for cleaning purposes. 
The present invention is useful with other components within the exhaust 
gas recirculation system. For example, a heat exchanger cooled by air, 
water, or other means, can be used to cool the exhaust gas prior to 
introduction into the recirculation manifolds. The linear shape of dual 
inlet manifold 42 provides a benefit to packaging of the EGR manifold and 
heat exchanger under the hood of a vehicle, particularly if the heat 
exchanger has a linear shape. It is understood that the present invention 
does not require the use of cooled exhaust gas. 
Also, the present invention is useful with one or more valves that regulate 
the supply of recirculated exhaust gas. Having such valves relatively 
close to the recirculation manifolds, combined with the relatively low 
internal volume of recirculation manifolds 42 and 142 and their 
alternatives, can result in improved transient response of the engine. It 
is known in the art that driveability of an internal combustion engine, 
especially during quick changes in load, can be improved by quick turnoff 
and purging of the EGR manifold. The present invention is useful with a 
quick responding exhaust gas recirculation control system by incorporating 
relatively low internal volume 49 and annular volume 149 within EGR 
manifolds 42 and its' alternatives, and manifold 142 and its' 
alternatives, respectively. It is preferrable, but not necessary, if 
internal volumes 49 and 149 are less than about twice the volume inducted 
by a piston 28 stroking within cylinder 27. 
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.