U.S. patent application number 11/544156 was filed with the patent office on 2008-04-10 for passive throttling valve outside of muffler.
This patent application is currently assigned to Arvin Technologies, Inc.. Invention is credited to Kwin Abram, Joseph Callahan, Robin Willats.
Application Number | 20080083218 11/544156 |
Document ID | / |
Family ID | 39273977 |
Filed Date | 2008-04-10 |
United States Patent
Application |
20080083218 |
Kind Code |
A1 |
Abram; Kwin ; et
al. |
April 10, 2008 |
Passive throttling valve outside of muffler
Abstract
An exhaust system includes an exhaust tube for conveying a
heated exhaust flow from an engine. A valve is mounted at least
partially within the exhaust tube for noise attenuation. The valve
includes a bias member mounted outside of the engine exhaust tube
within a heat transfer environment to maintain the bias member at a
low temperature. The bias member biases the valve against the heat
exhaust flow toward a predetermined position. The valve is mounted
within a section of the tube having a smaller cross-sectional area
and pivots into a larger cross-sectional area section of the
exhaust tube to avoid interference with tube walls and provide a
relatively large range of movement.
Inventors: |
Abram; Kwin; (Columbus,
IN) ; Callahan; Joseph; (Greenwood, IN) ;
Willats; Robin; (Columbus, IN) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD, SUITE 350
BIRMINGHAM
MI
48009
US
|
Assignee: |
Arvin Technologies, Inc.
|
Family ID: |
39273977 |
Appl. No.: |
11/544156 |
Filed: |
October 6, 2006 |
Current U.S.
Class: |
60/324 |
Current CPC
Class: |
F01N 1/165 20130101 |
Class at
Publication: |
60/324 |
International
Class: |
F01N 7/00 20060101
F01N007/00 |
Claims
1. An exhaust system comprising: an exhaust tube for conveying a
heated exhaust flow; a valve disposed at least partially within the
exhaust tube; and a bias member mounted outside of the exhaust
tube, the bias member biasing the valve against the heated exhaust
flow toward a predetermined position.
2. The exhaust system as recited in claim 1, wherein the bias
member is mounted within an ambient airflow heat transfer
environment that removes heat from the bias member to maintain the
bias member at a temperature below a threshold temperature.
3. The exhaust system as recited in claim 1, wherein the valve
includes a valve plate coupled to the bias member, and wherein the
exhaust tube includes a tube wall having a slot therein, and the
valve is mounted within the slot such that the valve plate is
within the exhaust tube.
4. The exhaust system as recited in claim 1, wherein the valve is
moveable between a plurality of positions including the
predetermined position, and the bias member comprises a spring rate
that varies between the plurality of positions.
5. The exhaust system as recited in claim 1, wherein the exhaust
tube includes a first section having a first cross-sectional area
adjacent a second section having a second cross-sectional area that
is larger than the first cross-sectional area.
6. The exhaust system as recited in claim 5, wherein the valve
includes a valve plate that is mounted at least partially within
the first section and is pivotable between a plurality of
positions, and in at least one of the plurality of positions, the
valve plate pivots into the second section.
7. The exhaust system as recited in claim 1, wherein the valve
includes a valve plate within the exhaust tube that is pivotable
between a minimum flow position and a maximum flow position,
wherein the valve plate permits the heated exhaust flow through the
exhaust tube in each of the minimum flow position and the maximum
flow position.
8. The exhaust system as recited in claim 1, wherein the valve
includes a valve plate within the exhaust tube that is pivotable
about a pivot axis that is located at an outer perimeter of the
valve plate.
9. The exhaust system as recited in claim 1, wherein the valve
includes a linkage connecting the valve and the bias member, the
linkage comprising a first link having one end pivotally secured
for rotation about a pivot axis of the valve, a second link having
an end pivotally secured for rotation about a pivot axis of the
bias member, and a third link that connects another end of the
first link to another end of the second link.
10. The exhaust system as recited in claim 9, wherein the first
link comprises a first nominal length, and the second link
comprises a second nominal length that is longer than the first
nominal length.
11. An exhaust system comprising: an exhaust tube for conveying a
heated exhaust flow, the exhaust tube comprising a first section
having a first cross-sectional area adjacent a second section
having a second cross-sectional area that is larger than the first
cross-sectional area; a valve mounted at least partially within the
first section, the valve operative to move between a plurality of
positions in response to a force exerted on the valve from the
heated exhaust flow, and wherein in one of the plurality of
positions, the valve extends into the second section.
12. The exhaust system as recited in claim 11, further comprising a
bias member that biases the valve toward a predetermined position
among the plurality of positions.
13. The exhaust system as recited in claim 12, wherein the
plurality of positions includes a minimum flow position where the
valve is generally perpendicular to a direction of the heated
exhaust gas flow through the exhaust tube, and a maximum flow
position where the valve is oriented 90.degree. relative to the
valve in the minimum flow position.
14. The exhaust system as recited in claim 13, wherein the
predetermined position comprises the minimum flow position.
15. The exhaust system as recited in claim 12, wherein the bias
member comprises a spring having a spring rate that varies between
the plurality of positions.
16. The exhaust system as recited in claim 11, wherein the valve
includes a pivot shaft having a pivot axis, and a valve plate
coupled to the pivot shaft for movement about the pivot axis,
wherein the valve plate is at least partially within the exhaust
tube.
17. The exhaust system as recited in claim 16, wherein the pivot
shaft is entirely outside of the exhaust tube.
18. A method of controlling a valve for use in an exhaust system,
comprising the steps of: mounting the valve within a first section
of an exhaust tube, the first section having a first
cross-sectional area; and moving the valve such that the valve
extends at least partially into a second section of the exhaust
tube having a second cross-sectional area that is larger than the
first cross-sectional area to avoid interference between the valve
and the second section.
19. The method recited in claim 18, further including biasing the
valve toward a predetermined position that is about perpendicular
to a direction of an exhaust gas flow through the first
section.
20. The method recited in claim 19, further including passively
moving the valve with a force provided by the exhaust flow to an
orientation that is about 90.degree. relative to the valve
predetermined position such that the valve extends into the second
section.
21. The method recited in claim 18, further including mounting a
bias member of the valve outside of the exhaust tube in an air flow
to maintain a temperature of the bias member below a temperature of
an exhaust gas flow through the exhaust tube.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to vehicle exhaust systems and, more
particularly, to a passive noise attenuation valve for use with an
exhaust tube of the vehicle exhaust system.
[0002] Exhaust systems are widely known and used with combustion
engines. Typically, the exhaust system includes exhaust tubes that
convey hot exhaust gases from the engine to a muffler. The muffler
includes acoustic chambers that cancel out sound waves carried by
the exhaust gases. Although effective, mufflers are often
relatively large in size and provide limited nose attenuation.
[0003] It has been proposed to utilize a valve within the exhaust
tubes to provide noise attenuation. However, the proposed valves
have numerous drawbacks that limit widespread use. For example, the
temperature of the hot exhaust gas is approximately 1000.degree.
C., and therefore the valve requires actuation mechanisms that
utilize special materials, that are relatively expensive, to
withstand the severe temperatures. Moreover, since the valves are
located within the exhaust tubes, they obstruct the flow of the
exhaust gases and thereby limit effectiveness of the valve for
noise attenuation. Therefore, there is a need for a more effective
noise attenuation valve that additionally improves exhaust flow.
This invention addresses those needs while avoiding the
shortcomings and drawbacks of the prior art.
SUMMARY OF THE INVENTION
[0004] In one aspect, an exhaust system includes an exhaust tube
for conveying a heated exhaust flow from an engine. A valve is
mounted at least partially within the exhaust tube for noise
attenuation. The valve includes a biasing member mounted outside of
the engine exhaust tube within a heat transfer environment to
maintain the biasing member at a low temperature. The biasing
member biases the valve against the heated exhaust flow toward a
predetermined position.
[0005] In one particular example, the valve is mounted within a
section of the exhaust tube having a reduced cross-sectional area
and is pivotable into a larger cross-sectional area section of the
exhaust tube to avoid interference with tube walls and provide a
relatively large range of movement.
[0006] In another example, the valve includes a four-bar linkage
that connects a valve plate of the valve to the biasing member. The
four-bar linkage varies an amount of force necessary to compress
the biasing member. In one example, the biasing member s a spring,
and the four-bar linkage varies a spring constant of the spring at
different rotational positions of the valve plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The various features and advantages of this invention will
become apparent to those skilled in the art from the following
detailed description of the currently preferred embodiment. The
drawings that accompany the detailed description can be briefly
described as follows.
[0008] FIG. 1 is a schematic view of an example exhaust system.
[0009] FIG. 2A is a perspective view of an example noise
attenuation device for use in the exhaust system.
[0010] FIG. 2B is a perspective view of an example valve within the
noise attenuation device.
[0011] FIG. 3 is a perspective view of an example exhaust tube for
mounting the valve.
[0012] FIG. 4 is a perspective view of an example noise attenuation
device having a valve plate in an open position.
[0013] FIG. 5 is a schematic view of an example linkage for
obtaining a variable spring constant within an example valve.
[0014] FIG. 6 is a schematic view of the example linkage of FIG. 5
in a rotated position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] FIG. 1 schematically illustrates selected portions of an
example exhaust system 20. In this example, the exhaust system 20
includes an engine 22, such as a gas combustion engine for use in a
vehicle. The engine 22 is connected to one or more exhaust tubes 24
for conveying hot exhaust gases from the engine 22 to a muffler 26.
A noise attenuation device 28 is associated with the exhaust tube
24 for reducing sound carried by the exhaust gases. Although, the
illustrated example includes the muffler 26, the noise attenuation
device 28 can be used without the muffler 26, or instead of the
muffler 26.
[0016] FIG. 2A illustrates a perspective view of one example noise
attenuation device 28. In this example, the noise attenuation
device 28 includes an exhaust tube section 40 connected to the
exhaust tube 24 from the engine 22 for conveying the heated exhaust
gases. A valve 42 is disposed at least partially within the exhaust
tube section 40 to attenuate noise carried by the exhaust
gases.
[0017] In one example, the engine 22 produces pressure pulses, or
acoustic waves, associated with combustion cycles of firing one or
more pistons. Noise is caused by the release of the pressure
pulses. The valve 42 of the noise attenuation device 28 reduces the
noise by reflection. The acoustic waves are reflected back and
forth within the exhaust system 20. At each reflection, the sound
waves lose energy. As result, only a fraction of the noise leaves
the exhaust system 20.
[0018] Referring to an isolated view of the valve 42 in FIG. 2B,
the valve 42 includes a valve plate 44 connected to a pivot shaft
46. The pivot shaft 46 extends through a frame 48, which supports
bushings 50 for pivotally supporting the pivot shaft 46. In this
example, a threaded member 52 is secured over an end of the pivot
shaft 46 that extends from the frame 48. A bias member 54, a spring
in this example, is received over the threaded member 52 and the
end of the pivot shaft 46 (for convenience of showing the threaded
member 52, the bias member 54 is not shown assembled in FIG. 2B).
Alternatively, the end of the pivot shaft 46 is threaded instead of
using the threaded member 52.
[0019] The bias member 54 includes a first extended portion 56a
that abuts a first arm 58a that extends from the frame 48. A second
extended portion 56b extends from the other end of the bias member
54 and abuts a second arm 58b that extends from a fastener 60 that
is received onto the threaded member 52.
[0020] In the illustrated example, the valve plate 44 extends into
the exhaust tube section 40 (FIG. 2A). In this example, the valve
plate 44 is contoured in an airfoil shape, to reduce resistance of
exhaust gas flow over a surface of the valve plate 44.
[0021] Referring to FIG. 3, the exhaust tube section 40 includes a
first section 70a and a second section 70b. In this example, the
first section 70a and second section 70b are generally round in
cross-section. The first section 70a includes a first
cross-sectional area associated with a diameter D.sub.1 of the
first section 70a. The second section 70b includes a second
cross-sectional area associated with the diameter D.sub.2 of the
second section 70b. In this example, the cross-sectional area of
the second section 70b is larger than the cross-sectional area of
the first section 70a.
[0022] The first section 70a includes a slot 72 for mounting the
valve 42. The slot 72 is near a transition section 74 between the
first section 70a and the second section 70b. The slot 72 includes
notches 76 at each corner of the slot 72 for receiving
corresponding portions of the frame 48. In this example, the frame
48 fits within the notches 76 to secure the valve 42 in place.
Optionally, the frame 48 is welded or secured in another known
manner to the exhaust tube section 40 to lock the valve 42 in
place. Alternatively, the valve 42 is mounted to walls of the
exhaust tube section 40 in a known manner without the slot 72. In
one example, the valve 42 is mounted within the first section 70a
of the exhaust tube section 40 before the first section 70a is
secured to the second section 70b. In another example, the first
section 70a is formed, such as by stamping, with a suitable
mounting portion for attaching the valve 42. Given this
description, one of ordinary skill in the art will recognize other
suitable designs for mounting the valve 42.
[0023] In this disclosed example, the bias member 54 biases the
valve plate 44 toward a predetermined, minimum flow position, such
as the position shown in FIG. 2A, wherein the valve plate 44 is
generally perpendicular to the flow of exhaust gases through the
exhaust tube section 40. In the disclosed example, the valve plate
44 is smaller than a cross-section of the exhaust tube section 40
such that in the minimum flow position, the valve plate 44 permits
the hot exhaust gases to flow through the exhaust tube section
40.
[0024] The bias member 54 is located outside of the exhaust tube
section 40. In this example, the bias member 54 is within a heat
transfer environment H that removes heat to maintain the bias
member 54 below a threshold temperature. For example, the exhaust
gas conveyed through the exhaust tube section 40 is approximately
1000.degree. C. A portion of the heat from the exhaust gas is
transferred through the valve plate 44 to the bias member 54. In
this example, the heat transfer environment H provides a
surrounding ambient airflow that removes and transfers the heat
away to maintain the bias member 54 at a lower temperature than the
exhaust gas. In one example, the lower temperature permits the bias
member 54 to be made from standard types of materials rather than
expensive, specialized materials for withstanding elevated
temperatures. In one example, the heat transfer environment H is a
relatively uncontained volume around the exhaust tube section 40,
such as an ambient airflow adjacent an undercarriage of a
vehicle.
[0025] Operationally, the valve 42 functions as a passive throttle
within the exhaust tube 24 to attenuate acoustic waves carried by
the exhaust gases. The valve plate 44 reflects a portion of the
acoustic waves to attenuate noise as described above. The valve
plate 44 pivots with the pivot shaft 46 about an axis A in response
to a force exerted on a valve plate 44 from the flow of the exhaust
gas. The valve plate 44 pivots between the minimum flow position
and a maximum flow position (FIG. 4) wherein the valve plate 44 is
oriented about 90.degree. relative to the minimum flow position to
permit the exhaust gas to flow through the exhaust tube 24.
[0026] Rotation of the pivot shaft 46 causes the threaded member 52
and fastener 60 to also rotate. Rotation of the fastener 60 moves
the second arm 58b against the second extended portion 56b of the
bias member 54. The first extended portion 56a of the bias member
54 presses against the first arm 58a and provides resistance to
rotation. Thus, movement of the valve plate 44 acts against the
biasing force provided by the bias member 54.
[0027] The flow of exhaust gases tends to move the valve plate 44
from the minimum flow position shown in FIG. 2 toward the maximum
flow position shown in FIG. 4. The difference in the
cross-sectional areas of the first section 70a and a second section
70b of the exhaust tube section 40 permits the valve plate 44 to
move to the maximum flow position without interfering with walls of
the second section 70b. In the minimum flow position, the valve
plate 44 is entirely within the first section 70a. When the valve
plate 44 pivots from the minimum flow position to the maximum flow
position, the valve plate 44 pivots into the second section 70b. In
the maximum flow position, the valve plate 44 is almost entirely
out of the flow path of the exhaust gases, approximately 90.degree.
from perpendicular. The unobstructed movement of the valve plate 44
and pivoting the valve plate 44 about axis A near a perimeter of
the exhaust tube section 40 (e.g., rather than about a central
pivot through the valve plate 44) provides the benefit of
minimizing obstruction of the exhaust gases through the exhaust
tube section 40. Additionally, as can be appreciated from the above
description, the valve 42 has relatively few moving parts, which
enhances durability of the valve 42.
[0028] FIG. 5 shows a schematic view of an alternative bias member
54. In this example, the arrangement includes a linkage 86, such as
a type of linkage commonly known in kinematics as a four-bar
linkage, that connects a valve plate 44' to the bias member 54'.
The valve plate 44' is pivotally connected about axis 0 to a first
link 88a. A second link 88b includes one end that is pivotally
secured for rotation about a pivot shaft 46', which is concentric
with the bias member 54' similar to as described above, such that
rotation of the pivot shaft 46' compresses the bias member 54'. A
third link 88c is pivotally connected with the other ends of the
first link 88a and the second link 88b.
[0029] Operationally, the first link 88a pivots with movement of
the valve plate 44' due to the force of the exhaust gas. Movement
of the first link 88a moves the third link 88c, which in turn
rotates the second link 88b against the bias force of the bias
member 54'.
[0030] In this example, the bias member 54' includes a spring
having a spring constant associated with the amount of force
necessary to compress the bias member 54' a given amount. In the
position shown in FIG. 5, a relatively large amount of force is
necessary to move the valve plate 44' against the bias force of the
bias member 54'. However, as shown in FIG. 6, as the first link 88a
and the second link 88b rotate counterclockwise in response to the
force of the exhaust gases, less force is needed to move the first
link 88a against the biasing force of the bias member 54'.
[0031] The amount of force and the spring constant can be
determined in a known manner at various rotational positions of the
valve plate 44' and depends on the length of the links 88a, 88b,
and 88c, angles between the links 88a, 88b, and 88c, angular
velocity, angular acceleration, and inertia of a given example. As
a result of the varying amount of force required to pivot the valve
plate 44', the spring constant is effectively changed over the
rotation of the valve plate 44'. Varying the effective spring
constant provides the benefit of tailoring the response of the
valve 42 in a desired manner over the rotational position of the
valve plate 44' based upon an expected exhaust gas flow.
[0032] Although a preferred embodiment of this invention has been
disclosed, a worker of ordinary skill in this art would recognize
that certain modifications would come within the scope of this
invention. For that reason, the following claims should be studied
to determine the true scope and content of this invention.
* * * * *