U.S. patent application number 11/764762 was filed with the patent office on 2007-10-18 for exhaust manifold flange.
Invention is credited to Darryl C. Bassani.
Application Number | 20070240409 11/764762 |
Document ID | / |
Family ID | 35423672 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070240409 |
Kind Code |
A1 |
Bassani; Darryl C. |
October 18, 2007 |
EXHAUST MANIFOLD FLANGE
Abstract
An exhaust header having a recessed sealing surface that
receives an annular graphite gasket for affecting a fluid tight
seal. The exhaust header further includes one or more exhaust head
pipe flanges and one or more exhaust head pipes. Each exhaust head
pipe flange is fixedly attached to one of the exhaust head pipes to
form a passageway through the exhaust header. During installation,
each exhaust head pipe flange is aligned with a passageway from an
exhaust port of an internal combustion engine. A one to one
registration between the exhaust head pipe flanges and the exhaust
ports is achieved. The gasket circumscribes the exhaust port when
the exhaust header is aligned with the surface of the internal
combustion engine. Torquing of one or more fasteners compresses the
gasket against the surface of the internal combustion engine to
form the fluid tight seal between the passageways of the exhaust
port and the exhaust header.
Inventors: |
Bassani; Darryl C.; (Yorba
Linda, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
35423672 |
Appl. No.: |
11/764762 |
Filed: |
June 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10787063 |
Feb 25, 2004 |
7231762 |
|
|
11764762 |
Jun 18, 2007 |
|
|
|
Current U.S.
Class: |
60/323 |
Current CPC
Class: |
F01N 13/10 20130101;
F01N 2450/24 20130101; F01N 13/1805 20130101; F01N 13/1827
20130101 |
Class at
Publication: |
060/323 |
International
Class: |
F01N 7/10 20060101
F01N007/10 |
Claims
1. An exhaust header for collecting exhaust gases from one or more
exhaust ports of an internal combustion engine, the header
comprising: a plurality of flanges, each having a passageway
extending therethrough and further comprising; a recessed seal
surface configured so as to support therein a gasket in a manner
such that at least a portion of the gasket is exposed to gas
flowing out the exhaust port, wherein the seal surface is
configured to circumscribe a single exhaust port; a web connecting
at least two of the plurality of flanges so as to inhibit relative
movement between the connected flanges; and a plurality of graphite
gaskets, each located on the seal surface and configured to form a
seal between the internal combustion engine and each flange.
2. The exhaust header of claim 1, wherein at least one of the
plurality of flanges is made of metal.
3. The exhaust header of claim 2, wherein the metal is iron.
4. The exhaust header of claim 1, wherein at least one of the
plurality of flanges comprises two bolt holes.
5. The exhaust header of claim 1, wherein the seal surface is
recessed approximately 0.1 inches.
6. The exhaust header of claim 1, wherein the seal surface has a
substantially annular shape.
7. The exhaust header of claim 1, wherein the seal surface has a
substantially rectangular shape.
8. The exhaust header of claim 1, wherein a cross-sectional area of
the passageway varies.
9. The exhaust header of claim 8, wherein the cross-sectional area
increases.
10. An exhaust header for collecting exhaust gases from a plurality
of exhaust ports from an internal combustion engine, the plurality
of exhaust ports being disposed in a surface of the engine, the
header comprising: a plurality of flanges, each having a passageway
extending therethrough and further comprising a plurality of bolt
holes, the plurality of bolt holes being disposed so as to receive
a fastener in a direction substantially perpendicular to the
surface of the engine, and a recessed seal surface configured so as
to support therein a gasket in a manner such that at least a
portion of the gasket is open to the passageway, the recessed seal
surface being configured to circumscribe a single exhaust port; a
web connecting two of the plurality of flanges so as to inhibit
relative movement between the connected flanges; and a graphite
gasket configured to be positioned against the seal surface and
form a seal between the internal combustion engine and the
flange.
11. The apparatus of claim 10, wherein at least one of the
plurality of flanges is made of metal.
12. The apparatus of claim 11, wherein the metal is iron.
13. The apparatus of claim 10, wherein the seal surface is recessed
approximately 0.1 inches.
14. An exhaust header for collecting exhaust gases from an internal
combustion engine, the engine having a mating surface through which
a plurality of exhaust ports expel exhaust gases, the exhaust
header comprising: a plurality of flanges configured to be
compressed toward the mating surface, each having a recessed
sealing surface configured to circumscribe one of the plurality of
exhaust ports, the recessed sealing surface being disposed so as to
support therein a gasket; a web connecting at least two of the
plurality of flanges so as to inhibit relative movement between the
connected flanges; and a plurality of gaskets comprising graphite
and configured to contact the mating surface, each being located in
the recessed sealing surface and configured to form separate seals
between each flange and the mating surface around one of the
plurality of exhaust ports.
15. The exhaust header of claim 14, wherein the web connects two
adjacent flanges.
16. The exhaust header of claim 14, wherein the web is configured
to contact the mating surface at least when the exhaust header is
attached to the engine.
17. The exhaust header of claim 14 further comprising at least two
bolt holes, wherein one of the two bolt holes is open to an edge of
the flange.
18. The exhaust header of claim 14, wherein the recessed sealing
surface has a substantially circular shape.
19. The exhaust header of claim 14, wherein the recessed sealing
surface has a substantially rectangular shape.
20. The exhaust header of claim 19, wherein the graphite gasket
comprises metal reinforcement.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of copending patent
application Ser. No. 10/787,063, filed Feb. 25, 2004, and titled
EXHAUST MANIFOLD FLANGE, the disclosure of which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to exhaust systems. More
particularly, the invention relates to an exhaust header for an
internal combustion engine.
[0004] 2. Description of the Related Art
[0005] Within the exhaust system of an engine, gaskets are used to
seal the interfaces between the connecting flanges of exhaust
pipes, or between an exhaust header flange or other exhaust
manifold and the cylinder head. In basic construction, these
gaskets are conventionally formed from a sheet consisting of one or
more layers of material. A plurality of apertures are formed in the
sheet for registration with the passageways of the exhaust pipes or
cylinder head and manifold. Bolts or other fasteners typically are
employed to develop compressive forces within the interface for
securing the assembly into an air tight joint.
[0006] Gaskets located between the header flange and the cylinder
head may further include metallic material such as copper, steel,
aluminum, or the like. Such a combination of a soft material along
with a metallic material provides additional rigidity to the
gasket. However, such conventional gaskets over time and under
repeated thermal cyclings, may have a tendency to develop a
compression set which, in turn, may result in a loss of torque
within the fasteners and a loosening of the joint. Moreover, as no
positive means typically is provided to limit or otherwise control
the compression of the gasket, the gaskets may be overcompressed
during an installation or maintenance which again leads to the
development of a compression set within the gasket.
SUMMARY OF THE INVENTION
[0007] One aspect is an exhaust header for collecting exhaust gases
from an internal combustion engine. The exhaust header comprises a
plurality of flanges, each having a recessed sealing surface that
is configured to circumscribe an exhaust port on an internal
combustion engine and a plurality of graphite gaskets, each located
in the recessed sealing surface and configured to form separate
seals between each flange and the engine around the exhaust port.
The exhaust header further comprises a plurality of head pipes in
flow communication with the plurality of flanges and configured to
route exhaust gases from the plurality of flanges and a collector
having a plurality of inlet ports connected to the plurality of
head pipes.
[0008] Another aspect is an apparatus configured to attach an
exhaust pipe to an engine head to form an exhaust header for
collecting exhaust gases from one or more exhaust ports from a
cylinder of an internal combustion engine. The apparatus comprises
a flange having a passageway extending therethrough, the flange
further comprises a mating surface configured for attachment to a
surface of the internal combustion engine. The flange further
comprises a seal surface recessed below the mating surface, wherein
the mating surface and the seal surface are configured to
circumscribe a single exhaust port, and wherein the mating surface
circumscribes the seal surface and a graphite gasket located on the
seal surface and configured to form a seal between the surface of
the internal combustion engine and the flange.
[0009] Another aspect is a method for installing an exhaust header
to a substantially flat surface of a multi-cylinder engine, the
exhaust header having a plurality of exhaust pipes, each exhaust
pipe being configured to collect exhaust gas from a cylinder of the
multi-cylinder engine. The method comprises providing an exhaust
header having a plurality of flanges, each flange having a mating
surface and a sealing surface, the sealing surface being recessed
below the mating surface, wherein the mating surface and the
sealing surface circumscribe an exhaust port from the cylinder and
placing a graphite gasket against each sealing surface in the
plurality of flanges. The method further comprises abutting each
graphite gasket against a substantially flat surface of the
multi-cylinder engine and individually compressing each graphite
gasket against the substantially flat surface of the engine so as
to form a plurality of separate seals between the plurality of
substantially flat surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of an internal combustion
engine and an exhaust header component of the exhaust system
attached thereto in accordance with the preferred embodiment of the
present invention.
[0011] FIG. 2A is a side view of an exhaust head pipe flange that
is a component of the exhaust header shown in FIG. 1.
[0012] FIG. 2B is a side view of the exhaust head pipe flange that
is a component of the exhaust header shown in FIG. 1.
[0013] FIG. 2C is a back view of the exhaust head pipe flange taken
from a location downstream of the exhaust head pipe flange.
[0014] FIG. 2D is a side view of the exhaust head pipe flange.
[0015] FIG. 2E is a front view of the exhaust head pipe flange
taken from a location upstream of the exhaust head pipe flange.
[0016] FIG. 2F is a side view of the exhaust head pipe flange
illustrating the flow direction of the exhaust gas through the
exhaust pipe flange.
[0017] FIG. 3A is a front view of a gasket that is a component of
the exhaust header shown in FIG. 1.
[0018] FIG. 3B is a cross-section view through the gasket shown in
FIG. 3A.
[0019] FIG. 4 is a front view of the exhaust head pipe flange
connected to an exhaust head pipe and farther comprising the gasket
shown in FIG. 3A located against the seal surface shown in FIG.
2E.
[0020] FIG. 5 is a section view of the assembled exhaust head pipe
flange, exhaust pipe, and gasket from FIG. 4 being aligned with an
exhaust port for attachment to the cylinder head with
fasteners.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] The preferred embodiments of the present invention will now
be described with reference to the accompanying figures, wherein
like numerals refer to like elements throughout. The terminology
used in the description presented herein is not intended to be
interpreted in any limited or restrictive manner simply because it
is being utilized in conjunction with a detailed description of
certain specific preferred embodiments of the present
invention.
[0022] User customization of exhaust components (such as headers)
is common in the after-market. Customization allows the user to
optimize the characteristics of their vehicle so as to maximize
their own satisfaction. A successful customization leads to
personal satisfaction of accomplishment and a feeling of attachment
to the vehicle. Such customization is achieved by replacement of a
component made by the original equipment manufacturer (OEM) with an
after-market component. In the case of exhaust systems,
incorporation of after-market components, for example, exhaust
pipes, headers, mufflers, catalytic converters, crossover pipes, or
other parts of the exhaust system, require the after-market
component to integrate with an OEM component. For example, the
replacement of an OEM exhaust manifold with an after-market exhaust
header requires the after-market exhaust header to interface with a
surface of the internal combustion engine of the vehicle. This
surface may include certain design features, for example, steps,
grooves, and attachment points, which impact the design of the
after-market exhaust header.
[0023] FIG. 1 is a perspective view of an internal combustion
engine 200 and an exhaust header component 202 of an exhaust system
attached thereto. The internal combustion engine 200 comprises,
among other components known to one having ordinary skill in the
art, a plurality of cylinders (not shown), with each cylinder
having an intake port and an exhaust port. Air and fuel enter each
cylinder through the intake port to form a mixture. After
combustion of the mixture occurs, the combustion by-products are
exhausted from the cylinder through the exhaust port. The
combustion by-products or exhaust gases then enter an exhaust
system. The exhaust system routes the exhaust gases a desired
distance before expelling the exhaust gases from the vehicle.
[0024] In the embodiment of the invention shown in FIG. 1, the
internal combustion engine 200 comprises eight cylinders in two
banks of four cylinders each. The banks of cylinders are arranged
in a V-configuration. Each of the cylinder banks is associated with
and has fixedly attached a cylinder head 204. For ease of
description, only the cylinder head 204 on the right or passenger
side of the internal combustion engine 200 is described herein.
However, as would be obvious to one having ordinary skill in the
art, the following description equally applies to the left or
driver side of the internal combustion engine 200. Moreover,
features of the present invention can be used with internal
combustion engines with different numbers of cylinders and
different configurations of cylinders, or even rotary engines.
[0025] Returning to FIG. 1, the cylinder head 204 and the four
cylinders together form four combustion chambers within the engine.
Cylinder head 204 incorporates at least one intake port and at
least one exhaust port for ingress and egress to each of the four
cylinders. Each intake and exhaust port may include one or more
valves which control the timing of flow into and out of the
cylinders.
[0026] The geometry of the exhaust port opening at an exit plane of
the exhaust ports can be, for example, oval, square, rectangular,
round, or a combination thereof. Preferably, the inner geometry of
the mating surfaces on the exhaust head pipe flanges are selected
to match the geometry of the exhaust port at the exit plane. In
this way, exhaust recirculation, backpressure, and thermal stresses
induced by hot gas flow can be reduced. The exit angle of the
exhaust gases leaving the exhaust ports relative to the exit plane
of the exhaust ports can also be matched to the entrance angle into
the exhaust header 202 to improve engine performance.
[0027] The exhaust header 202 comprises exhaust head pipe flanges
214, 216, 218, 220, exhaust head pipes 206, 208, 210, 212, webs
232, 234, 236 and collector 224. Located between the exhaust head
pipe flanges 214, 216, 218, 220 and the cylinder head 204 are
gaskets. The gaskets are described with reference to FIGS. 3-5. The
exhaust header 202 provides individual passageways for the exhaust
gases exiting the exhaust ports. The exhaust header 202 for the
right or passenger side of the internal combustion engine 200
illustrated in FIG. 1 provides four individual passageways. Each
passageway is formed by one exhaust head pipe flange 214, 216, 218,
220 and one exhaust head pipe 206, 208, 210, 212. In the embodiment
of FIG. 1, the exhaust head pipe flange 214 is fixedly attached to
the exhaust head pipe 206. The exhaust head pipe flange 216 is
fixedly attached to exhaust head pipe 208. The exhaust head pipe
flange 218 is fixedly attached to the exhaust head pipe 210. The
exhaust head pipe flange 220 is fixedly attached to the exhaust
head pipe 212.
[0028] The downstream ends of the exhaust head pipes 206, 208, 210,
212 are joined at collector 224. The collector 224 receives pulses
of the exhaust gases from the internal combustion engine 200, then
combines the pulses. Depending on the relative lengths of the four
passageways through the exhaust header 202 and the timing of the
exhaust valves, one or more pulses may arrive at the collector 224
together or as a series of pulses. The collector 224 provides the
pulses to the portion of the exhaust system (not shown) that is
downstream of the exhaust header 202. For example, the portion of
the exhaust system that is downstream of the exhaust header 202 may
include a pre-catalytic converter, a main catalytic converter, one
or more mufflers, resonators, and exhaust pipes connecting
therebetween.
[0029] The exhaust system may be in flow communication with exhaust
pulses from the second bank of cylinders of the internal combustion
engine 200. In such a configuration, the exhaust is combined via a
crossover pipe or other such means to allow the combined pulses
from one bank of cylinders to communicate with the combined pulses
from a second bank of cylinders downstream of.the collector 224.
For simplicity purposes, the exhaust system downstream of the
collector 224 is not shown.
[0030] The internal combustion engine 200 further comprises a valve
cover 226 which forms a housing for one or more valve train
components which are associated with the intake and/or exhaust
ports in the cylinder head 204.
[0031] As illustrated in FIG. 1, the exhaust header 202 interfaces
with the cylinder head 204 along surface 606. Each of the head pipe
flanges 214, 216, 218, 220 independently interfaces with the
surface 606. Webs 232, 234, 236 are located between each adjacent
exhaust head pipe flange 214, 216, 218, 220. The web 232 connects
the exhaust head pipe flange 214 with the exhaust head pipe flange
216. The web 234 connects the exhaust head pipe flange 216 with the
exhaust head pipe flange 218. The web 236 connects the exhaust head
pipe flange 218 with the exhaust head pipe flange 220. The webs
232, 234, 236 provide additional structural rigidity to the exhaust
header 202. However, the webs 232, 234, 236 are not required to
practice the invention. Alternatively, more than one web can be
used to connect adjacent head pipe flanges 214, 216, 218, 220.
[0032] The pulses of exhaust gas exiting the cylinder head 204
enter the exhaust head pipes 206, 208, 210, 212 via the exhaust
head pipe flanges 214, 216, 218, 220. The exhaust head pipes 206,
208, 210, 212 are preferably made from a metallic material, for
example, aluminum or steel. For example, the exhaust head pipes
206, 208, 210, 212 can be made from 14-gauge steel with an outside
diameter of 1 and 5/8 inches.
[0033] The collector 224 is made from a metallic material and is
fixedly attached to the exhaust pipes 206, 208, 210, 212 by welding
or other means know in the art.
[0034] FIGS. 2A through 2F illustrate an exhaust head pipe flange
214, 216, 218, 220 which is a component of the exhaust header 202
shown in FIG. 1. In the embodiment illustrated in FIG. 1, the
exhaust header 202 comprises four exhaust head pipe flanges 214,
216, 218, 220. However, one who is skilled in the art will
appreciate that the exhaust header 202 can incorporate more or less
exhaust head pipe flanges depending on the number of cylinders in
the cylinder bank. For example, in a multi-cylinder engine that
comprises a total of six cylinders with three cylinders arranged in
two opposing banks, the exhaust header 202 would comprise three
exhaust head pipe flanges. Moreover, additional head pipe flanges
can be incorporated into the exhaust header 202 when the
multi-cylinder engine comprises more than eight cylinders.
[0035] FIGS. 2A and 2B are side views of an exemplary exhaust head
pipe flange 214. The exhaust head pipe 206 which forms a passageway
together with the exhaust head pipe flange 214 is not shown in
FIGS. 2A-2F. The following description applies equally to the
exhaust head pipe flanges 216, 218, 220.
[0036] Preferably, the inner dimensions or shape of the passageway
through the exhaust head pipe flange 214 is selected depending on
the shape of the exhaust port at the exit plane of the cylinder
head 204 and the inside diameter of the exhaust head pipe 206 that
is fixedly attached to the exhaust head pipe flange 214. The shape
of the passageway may increase or decrease along the length of the
exhaust head pipe flange 214. In this way, the inner dimensions or
shape can provide a smooth transition between the exhaust port and
the inside diameter of the exhaust head pipe 206.
[0037] Moreover, the shape may increase in one dimension along the
length of the exhaust head pipe flange 214 while a second dimension
decreases along the length of the exhaust head pipe flange 214. For
example, the exhaust head pipe flange 214 illustrated in FIGS.
2A-2F transitions or adapts a rectangular exit port to a circular
exhaust head pipe 206. As illustrated in FIGS. 2A and 2B, a first
inner dimension of the exhaust head pipe flange 214 increases along
axis 222 in a downstream or exhaust flow direction. A second inner
dimension measured perpendicular to the axis 222 decreases in a
downstream direction. Even though the shape of the passageway
through the embodiment illustrated in FIGS. 2A-2F varies along its
length, the shape of the passageway through the exhaust head pipe
flange 214 is not required to increase or decrease to practice the
invention. An alternate embodiment of the exhaust head pipe flange
214 has a conical inner shape which connects a circular exhaust
port to a larger circular exhaust head pipe 206.
[0038] FIG. 2C is a back view of the exhaust head pipe flange 214
taken from a location downstream of the exhaust head pipe flange
214. During fabrication of the exhaust header 202, the exhaust head
pipe 206 is fixedly attached to the exhaust head pipe flange 214 on
surface 312. Inside diameter 304 is selected to be equal to or less
than the inside diameter of the exhaust head pipe 206 to prevent
the exhaust head pipe 206 from protruding into the exhaust gas flow
path 302 (see FIG. 2F). In this way, the inside diameter of the
exhaust head pipe 206 and the inside diameter of the exhaust head
pipe flange 214 form a smooth transition therebetween. In the
preferred embodiment illustrated in FIG. 2C, the inside diameter of
the exhaust head pipe flange 214 and the inside diameter of the
surface 312 are 1.5 inches. The outside diameter of the surface 312
is 1.65 inches. In such a configuration, the exhaust head pipe 206
has a wall thickness of approximately 0.15/2=0.075 inches. As shown
in FIGS. 2A and 2D, the surface 312 can be approximately 0.75
inches from the upstream surface of the exhaust head pipe flange
214.
[0039] FIG. 2E is a front view of the exhaust head pipe flange 214
and illustrates a rectangular seal surface 306 which receives a
gasket (not shown). However, the invention is not so limited. The
seal surface 306 can have other shapes, for example, oblong, round
or elliptical. The shape of the seal surface can be selected
depending upon the exhaust port geometry of the cylinder head
204.
[0040] The seal surface 306 circumscribes the exhaust port of the
cylinder head 204 (see FIG. 1). In the preferred embodiment, the
seal surface 306 is recessed or inset into the exhaust head pipe
flange 214. For example, as illustrated in FIG. 2F, the seal
surface 306 is recessed a distance X from a mating or outer surface
of the exhaust head pipe flange 214. Dimension X is selected
depending on the thickness of the gasket that is placed against the
seal surface 306. For example, dimension X can be selected so that
when the gasket is placed against the seal surface 306 the gasket
will protrude above the mating surface of the exhaust head pipe
flange 214. In one embodiment, the dimension X is approximately
0.08 inches.
[0041] FIG. 2F is a side view of the exhaust head pipe flange
illustrating the flow direction of the exhaust gas through the
exhaust head pipe flange 214. The exhaust head pipe flange 214
further comprises bolt holes 308, 310. In the embodiment shown in
FIG. 2C, the bolt holes 308, 310 are located on different sides of
axis 222. Alternatively, more or less bolt holes could be
incorporated in the exhaust head pipe flange 214 depending on the
mating configuration of the surface 606 of the cylinder head 204.
Moreover, one or more bolt holes could be further incorporated in
the webs 232, 234, 236 (see FIG. 1) if corresponding bolt holes
were provided in the cylinder head 204.
[0042] FIG. 3A is a front view of a gasket 400 that is a component
of the exhaust header 202 shown in FIG. 1. Each exhaust head pipe
flange 214, 216, 218, 220 is associated with its own gasket 400.
Thus, the exhaust header 202 illustrated in FIG. 1 includes four
gaskets 400. Each gasket 400 is placed against the seal surface 306
on each of the exhaust head pipe flanges 214, 216, 218, 220 prior
to attaching the exhaust header 202 to the internal combustion
engine 200. Once the exhaust header 202 is attached to the internal
combustion engine 200, each gasket 400 is compressed between the
exhaust head pipe flanges 214, 216, 218, 220 and the cylinder head
204.
[0043] As illustrated in FIG. 3B, the gasket can have a rectangular
cross-sectional shape that matches the geometry of the seal surface
306. The gasket 400 is made from a graphite material or graphite
composite. An exemplary gasket can be obtained from Seal Systems
located in Santa Fe Springs, Calif., Part No. 4603IN. One
embodiment of the gasket 400 comprises metal-reinforced graphite
with a 0.093 inch minimum thickness. Alternatively, the gasket 400
can have a cylindrical cross-sectional shape while still
maintaining the overall rectangular shape as illustrated in FIG.
3A.
[0044] Dimension E in FIG. 3B illustrates the thickness of the
gasket 400. Dimension E is selected to be greater than dimension X
as illustrated in FIG. 2F. In this way, when the gasket 400 is
placed against the seal surface 306 prior to attachment to the
cylinder head 204, the gasket 400 will protrude above the mating or
outer surface of the exhaust head pipe flange 214. During
installation of the exhaust header 202 against the cylinder head
204, the gasket 400 is compressed sufficiently to provide a seal
between the cylinder head 204, the gasket 4005 and the seal surface
306. For example, the gasket 400 can be compressed approximately
0.010-0.015 inches by applying a torque of approximately 15-18
foot-lbs. to bolts 602, 604 during installation.
[0045] In a preferred embodiment, dimension E is 0.093 inches thick
with the exhaust head pipe flange 214 dimension X being 0.080
inches deep. Advantageously, recessing a portion of the gasket 400
below the outer surface of the exhaust head pipe flange 214, 216,
218, 220 limits the amount of compression applied to the gasket 400
during installation. Limiting compression reduces the chance that
the gasket 400 becomes pinched or non-uniformly deformed.
[0046] FIG. 4 is a view looking downstream from the cylinder head
204 showing the gasket 400 placed against the seal surface 306 of
the exhaust head pipe flange 214. The exhaust head pipe 206 is
further shown attached to the downstream side of the exhaust head
pipe flange 214.
[0047] FIG. 5 is a cross-section view from FIG. 4 showing the
exhaust head pipe flange 214, the exhaust head pipe 206, and gasket
400 prior to mating with the interface surface 606 of the cylinder
head 204. Casket 400 is disposed between the interface surface 606
of the cylinder head 204 and the seal surface 306 of the exhaust
head pipe flange 214 with the gasket 400 opening in general coaxial
registration with the corresponding exhaust gas passageway from the
internal combustion engine 200.
[0048] As illustrated in FIG. 5, the gasket 400 protrudes beyond
the outer or mating surface of the exhaust head pipe flange 214.
Bolts or fasteners 602, 604 are used to apply a compressive load
between the exhaust head pipe flange 214 and the cylinder head 204.
Upon the tightening of the bolts 602, 604 to a predetermined
torque, the gasket 400 is compressed between the interface surface
606 to a thickness that is less than the original thickness of the
gasket 400. The compressive load forms a seal between the gasket
400 and the cylinder head 204 as well as between the gasket 400 and
the seal surface 306. In this regard, as the gasket 400 of the
present invention is compressed under the torque of the bolts or
other fastening members, it affects a fluid tight seal of the
corresponding fluid passageways of the exhaust head pipe flange and
cylinder head. That is, the gasket 400 exhibits a reduced-yield
stress as compared to the exhaust head pipe flange 214 and,
accordingly, is deformable for conforming to any irregularities
between the interface surfaces of the cylinder head 204. As a given
compressive load is applied by the tightening of the bolts 602, 604
which fasten the interface surfaces of the exhaust head pipe flange
214, an increased bearing stress is provided about the fluid
passageways of the cylinder head 204 by virtue of the reduced
surface area contact of the gasket 400 on the interface surface 606
of the cylinder head 204.
[0049] Additionally, defined within the interface surface 606 are a
plurality of bores, two of which are referenced at 608, 610 for
exhaust head pipe flange 214. Each of the bores of each exhaust
head pipe flange 214, 216, 218, 220 is aligned with a corresponding
bore or bolt hole in the cylinder head 204 to define a hole
configured to receive an associated bolt or fastening member. The
associated fasteners are illustrated as a threaded bolts 602, 604.
Bolts 602, 604 connect the exhaust head pipe flange 214, 216, 218,
220 and are tightened to a predetermined torque to affect the
compression of gasket 400 in a sealing engagement between the
interface surface 606 and the exhaust head pipe flange. The two
threaded bolts associated with one exhaust head pipe flange can be
torqued independent of the threaded fasteners associated with the
other exhaust head pipe flanges. Alternatively, the threaded bolts
associated with a plurality of exhaust head pipe flanges are
torqued in series to evenly distribute the compressive load across
the entire exhaust header 202.
[0050] The various embodiments of the exhaust header and techniques
described above thus provide a number of ways to provide a fluid
tight and releasable seal between the exhaust header and an engine.
The combination of separate gaskets, individual recesses, and
graphite material provides a more robust seal between the engine
block and the exhaust header. For example, the recesses provide
additional lateral support to the gaskets. The recesses further
limit the amount of compression experienced by the gaskets during
assembly of the exhaust manifold to the engine. This additional
support and the limits on compression allow a gasket material that
has limited flexibility to be utilized.
[0051] For example, these features enhance the longevity of a
graphite gasket located within the recess. Without the additional
lateral support, a substantial core material may need to be
incorporated into the graphite gasket to help the graphite gasket
maintain its shape under high exhaust gas pressure. However, a
substantial core material may expand at a different rate than the
graphite material and lead to degradation of the seal over
time.
[0052] The use of multiple gaskets for the exhaust header allows
each gasket to be individually seated against the engine. Movement
or shifting during assembly or engine operation does not affect
adjacent gaskets of the exhaust header. In this way, the location
of each gasket can be individually optimized during assembly and
engine operation to provide a more robust seal between all of the
gaskets of the exhaust header and the engine.
[0053] Of course, it is to be understood that not necessarily all
such objectives or advantages may be achieved in accordance with
any particular embodiment using the exhaust systems described
herein. Thus, for example, those skilled in the art will recognize
that the systems may be developed in a manner that achieves or
optimizes one advantage or group of advantages as taught herein
without necessarily achieving other objectives or advantages as may
be taught or suggested herein. In addition, the techniques
described may be broadly applied for use with a variety of engines
and exhaust systems.
[0054] Furthermore, the skilled artisan will recognize the
interchangeability of various features from different embodiments.
Although these techniques and systems have been disclosed in the
context of certain embodiments and examples, it will be understood
by those skilled in the art that these techniques and systems may
be extended beyond the specifically disclosed embodiments to other
embodiments and/or uses and obvious modifications and equivalents
thereof. Thus, it is intended that the scope of the systems
disclosed herein disclosed should not be limited by the particular
disclosed embodiments described above.
* * * * *