U.S. patent application number 11/765520 was filed with the patent office on 2007-11-08 for motorcycle dynamic exhaust system.
This patent application is currently assigned to Harley-Davidson Motor Company Group, Inc.. Invention is credited to Alexander J. Bozmoski, Michael P. Christopherson, Anthony L. Coffey, Timothy R. Osterberg, William P. Pari, Richard G. Pierson, Michael R. Richter, Michael A. Selwa, Stacy L. Smith.
Application Number | 20070256673 11/765520 |
Document ID | / |
Family ID | 35508207 |
Filed Date | 2007-11-08 |
United States Patent
Application |
20070256673 |
Kind Code |
A1 |
Bozmoski; Alexander J. ; et
al. |
November 8, 2007 |
MOTORCYCLE DYNAMIC EXHAUST SYSTEM
Abstract
The present invention provides a method of operating a dynamic
exhaust system of a motorcycle engine. The method includes
providing a valve in the exhaust system that is movable to direct
exhaust gases between a first flow path through the exhaust system
and a second flow path through the exhaust system. The method
includes actuating the valve at a first speed to redirect exhaust
gases from the first flow path to the second flow path and
actuating the valve at a second speed greater than the first speed
to redirect exhaust gases from the second flow path to the first
flow path.
Inventors: |
Bozmoski; Alexander J.;
(Brookfield, WI) ; Osterberg; Timothy R.;
(Hubertus, WI) ; Christopherson; Michael P.;
(Waukesha, WI) ; Coffey; Anthony L.; (Cedarburg,
WI) ; Pari; William P.; (Waukesha, WI) ;
Richter; Michael R.; (East Troy, WI) ; Smith; Stacy
L.; (Oconomowoc, WI) ; Pierson; Richard G.;
(New Berlin, WI) ; Selwa; Michael A.; (Oconomowoc,
WI) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH LLP
100 E WISCONSIN AVENUE
Suite 3300
MILWAUKEE
WI
53202
US
|
Assignee: |
Harley-Davidson Motor Company
Group, Inc.
3700 West Juneau Avenue
Milwaukee
WI
53208
|
Family ID: |
35508207 |
Appl. No.: |
11/765520 |
Filed: |
June 20, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10881189 |
Jun 30, 2004 |
|
|
|
11765520 |
Jun 20, 2007 |
|
|
|
Current U.S.
Class: |
123/568.11 |
Current CPC
Class: |
F01N 2410/10 20130101;
F01N 13/14 20130101; F01N 13/08 20130101; F01N 1/166 20130101; F01N
1/083 20130101; F01N 1/24 20130101; F01N 2470/02 20130101; F01N
13/0097 20140603; F01N 1/084 20130101; F02D 9/04 20130101; F01N
2470/24 20130101; F01N 13/011 20140603; F01N 3/2885 20130101; F01N
2590/04 20130101; F01N 13/087 20130101; F01N 2470/18 20130101 |
Class at
Publication: |
123/568.11 |
International
Class: |
F01N 7/08 20060101
F01N007/08 |
Claims
1. A method of operating a dynamic exhaust system of a motorcycle
engine, the method comprising: directing exhaust gases along a
first flow path through the exhaust system to operate the engine at
a first torque characteristic; actuating a valve in the exhaust
system in a crossover region of the first torque characteristic and
a second torque characteristic; and redirecting the exhaust gases
from the first flow path to a second flow path through the exhaust
system to operate the engine at the second torque
characteristic.
2. The method of claim 1, further comprising: actuating the valve
in a second crossover region of the first torque characteristic and
the second torque characteristic; and redirecting the exhaust gases
from the second flow path to the first flow path to operate the
engine at the first torque characteristic.
3. The method of claim 1, wherein actuating the valve includes one
of opening and closing the valve.
4. The method of claim 1, wherein actuating the valve occurs when
the engine is operating at least about 75 percent of full
throttle.
5. The method of claim 1, further comprising triggering an actuator
to actuate the valve.
6. The method of claim 5, wherein an engine control unit
selectively triggers the actuator.
7. The method of claim 1, wherein the crossover region is a range
of engine speeds over which the first torque characteristic and the
second torque characteristic are substantially equal.
8. The method of claim 7, further comprising monitoring the engine
speed with an engine control unit, wherein the valve is selectively
actuated by the engine control unit.
9. A motorcycle comprising: an exhaust system defining a first flow
path and a second flow path; a valve positioned in the exhaust
system, the valve operable to direct exhaust gases between the
first flow path and the second flow path; an airbox positioned
remotely from the exhaust system; and an actuator supported by the
airbox and operatively coupled to the valve to move the valve
between a first position, in which exhaust gases are directed along
the first flow path, and a second position, in which exhaust gases
are directed along the second flow path.
10. The motorcycle of claim 9, further comprising a cable
operatively coupling the actuator and the valve.
11. The motorcycle of claim 8, further comprising an engine control
unit adapted to trigger the actuator to move the valve between the
first and second positions.
12. The motorcycle of claim 11, further comprising an engine
operable over a range of engine speeds, the engine exhibiting a
first torque characteristic when exhaust gases are directed through
the first flow path, the engine further exhibiting a second torque
characteristic when exhaust gases are directed through the second
flow path.
13. The motorcycle of claim 12, wherein the engine control unit is
configured to selectively trigger the actuator based on engine
speed.
14. The motorcycle of claim 13, wherein the engine control unit is
configured to selectively trigger the actuator at an engine speed
within a crossover region, in which the first torque characteristic
is substantially equal to the second torque characteristic.
15. The motorcycle of claim 9, wherein the exhaust system includes
a muffler, and wherein the valve is located inside of the
muffler.
16. The motorcycle of claim 9, wherein the exhaust system includes
a first muffler and a second muffler, wherein the valve directs
exhaust gases through the first muffler along the first flow path,
and wherein the valve substantially prevents exhaust gases from
entering the first muffler along the second flow path.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. patent application
Ser. No. 10/881,189, filed on Jun. 30, 2004, the entire contents of
which are incorporated by reference.
BACKGROUND
[0002] This invention relates generally to motorcycles, and more
particularly to dynamic exhaust systems for motorcycles.
[0003] Various designs of motorcycle dynamic exhaust systems are
known in the art. Typically, dynamic exhaust systems are utilized
to alter the performance of the motorcycle's engine and/or the
noise emissions from the motorcycle's engine. In a conventional
dynamic exhaust system for a motorcycle, a valve is positioned in a
muffler to define a restrictive flow path through the muffler,
which may be utilized when it is desirable to decrease the noise
emissions of the engine, and a less restrictive flow path, which
may be utilized when it is desirable to increase the performance of
the engine. The valve is typically moved to direct exhaust gases
from the engine through either of the restrictive or less
restrictive flow paths. An actuator that is responsive to engine
vacuum is commonly utilized to actuate the valve, such that when
engine vacuum is high, the actuator actuates the valve to direct
the exhaust gases through the restrictive flow path of the muffler
to quiet the engine. Also, when the engine vacuum is low, the
actuator actuates the valve to direct the exhaust gases through the
less restrictive flow path of the muffler to increase the
performance of the engine.
SUMMARY
[0004] The present invention provides a method of operating a
dynamic exhaust system of a motorcycle engine. The method includes
providing a valve in the exhaust system that is movable to direct
exhaust gases between a first flow path through the exhaust system
and a second flow path through the exhaust system. The method
includes actuating the valve at a first speed to redirect exhaust
gases from the first flow path to the second flow path and
actuating the valve at a second speed greater than the first speed
to redirect exhaust gases from the second flow path to the first
flow path.
[0005] The method includes, in another aspect, actuating the valve
in the exhaust system in a crossover region of first and second
torque characteristics of the first and second flow paths,
respectively.
[0006] The present invention provides, in yet another aspect, a
motorcycle including a valve and an actuator supported by an
airbox. The actuator is operatively coupled to the valve to move
the valve between a first position, in which exhaust gases are
directed along the first flow path, and a second position, in which
exhaust gases are directed along the second flow path.
[0007] Other features and aspects of the present invention will
become apparent to those skilled in the art upon review of the
following detailed description, claims and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] In the drawings, wherein like reference numerals indicate
like parts:
[0009] FIG. 1 is a cross-sectional view of a first construction of
a dynamic exhaust system embodying the present invention,
illustrating exhaust gases flowing through a first flow path of the
exhaust system.
[0010] FIG. 2 is a cross-sectional view of the dynamic exhaust
system of FIG. 1, illustrating exhaust gases flowing through a
second flow path of the exhaust system.
[0011] FIG. 3 is a partial cross-sectional view of a second
construction of a dynamic exhaust system embodying the present
invention, illustrating exhaust gases flowing through a first flow
path of the exhaust system.
[0012] FIG. 4 is a partial cross-sectional view of the dynamic
exhaust system of FIG. 3, illustrating exhaust gases flowing
through a second flow path of the exhaust system.
[0013] FIG. 5 is a cutaway perspective view of a third construction
of a dynamic exhaust system embodying the present invention,
illustrating exhaust gases flowing through a first flow path of the
exhaust system.
[0014] FIG. 6 is a cutaway perspective view of the dynamic exhaust
system of FIG. 5, illustrating exhaust gases flowing through a
second flow path of the exhaust system.
[0015] FIG. 7 is a perspective view of a motorcycle including the
dynamic exhaust system of FIGS. 5 and 6, illustrating an actuator
positioned remotely from the exhaust system.
[0016] FIG. 8 is a graph illustrating a first torque characteristic
of a motorcycle engine representative of exhaust gases flowing
through the first flow path of the exhaust system of FIGS. 5 and 6,
and a second torque characteristic of the motorcycle engine
representative of exhaust gases flowing through the second flow
path of the exhaust system of FIGS. 5 and 6.
[0017] Before any features of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangements
of the components set forth in the following description or
illustrated in the drawings. The invention is capable of other
embodiments and of being practiced or being carried out in various
ways. Also, it is understood that the phraseology and terminology
used herein is for the purpose of description and should not be
regarded as limiting. The use of "including", "having", and
"comprising" and variations thereof herein is meant to encompass
the items listed thereafter and equivalents thereof as well as
additional items. The use of letters to identify elements of a
method or process is simply for identification and is not meant to
indicate that the elements should be performed in a particular
order.
DETAILED DESCRIPTION
[0018] FIGS. 1 and 2 illustrate a first construction of a
motorcycle dynamic exhaust system 10 embodying the present
invention. The exhaust system 10 includes a muffler 14 coupled to
an exhaust pipe 18 in a conventional manner. Although not shown,
the exhaust system 10 may incorporate a second exhaust pipe and a
second muffler.
[0019] The muffler 14 incorporates a valve assembly 22a to direct
the flow of exhaust gases through the muffler 14. In the
illustrated construction, the valve assembly 22a includes a valve
housing 26 defining a central passageway 30. A shaft 34 is
rotatably supported by the valve housing 26, and a butterfly valve
38 is coupled to the shaft 34. The butterfly valve 38 is positioned
in the central passageway 30 to selectively restrict the flow of
exhaust gases through the passageway 30, as discussed in more
detail below. The shaft 34 extends through an outer shell 42 of the
muffler 14, and a quadrant or a lever 46 is coupled to the shaft 34
to receive a cable 50 for pivoting or rotating the shaft 34 and the
butterfly valve 38.
[0020] The muffler 14 also includes an inlet tube 54 coupled to the
valve housing 26 at an inlet end of the valve housing 26, and an
outlet tube 58 coupled to the valve housing 26 at an outlet end of
the valve housing 26. The inlet tube 54 is supported in the outer
shell 42 of the muffler 14 by a tube support member 62. The muffler
14 further includes a catalyst 66 located within a catalyst tube
70, which is coupled to the inlet tube 54 via a transition sleeve
74. A first sleeve 78 surrounds the inlet tube 54 and is coupled
between the tube support member 62 and the transition sleeve 74. A
plug 82 is positioned within the inlet tube 54 such that
unobstructed flow of exhaust gases through the entire length of the
inlet tube 54 is restricted.
[0021] With continued reference to FIGS. 1 and 2, the muffler 14
includes a second sleeve 86 surrounding the outlet tube 58, such
that opposite ends of the second sleeve 86 are pinched into contact
with the outer surface of the outlet tube 58. The muffler 14 also
includes a third sleeve 90 surrounding the second sleeve 86, with
one end of the third sleeve 90 being coupled to the tube support
member 62 and the opposite end being in abutting contact with the
outer shell 42.
[0022] As a result of the above-identified internal components of
the muffler 14, the muffler 14 generally defines a plurality of
chambers through which exhaust gases may flow. More particularly,
the space bounded by the catalyst tube 70, the transition sleeve
74, and a portion of the inlet tube 54 upstream of the plug 82
defines a first chamber 94, while the space bounded by the first
sleeve 78, the inlet tube 54, the transition sleeve 74, and the
tube support member 62 defines a second chamber 98. In addition,
the space bounded by a portion of the inlet tube 54 downstream of
the plug 82 and the closed butterfly valve 38 defines a third
chamber 102, and the space bounded between the second sleeve 86,
and the third sleeve 90, and the tube support member 62 defines a
fourth chamber 106. Further, the space bounded by the second sleeve
86 and the outlet tube 58 defines a fifth chamber 110, while the
space bounded by the closed butterfly valve 38 and the outlet tube
58 defines a sixth chamber 114.
[0023] With reference to FIG. 1, a first flow path of exhaust gases
is shown through the muffler 14 by a sequence of arrows. The
butterfly valve 38 is shown pivoted to an open position, in which
unobstructed flow of exhaust gases is allowed through the
passageway 30 in the valve housing 26. More particularly, exhaust
gases exiting the exhaust pipe 18 enter the first chamber 94 of the
muffler 14 and encounter the plug 82, which redirects the ehxuast
gases into the second chamber 98 via a plurality of first apertures
118 formed in the inlet tube 54. The exhaust gases are then
directed into the third chamber 102 via a plurality of second
apertures 122 formed in the inlet tube 54. From the third chamber
102, the exhaust gases may pass unobstructed through the passageway
30 of the valve housing 26 and enter the sixth chamber 114, thereby
bypassing the fourth and fifth chambers 106, 110 of the muffler 14.
From the sixth chamber 114, the exhaust gases may exit the muffler
14.
[0024] With reference to FIG. 2, a second flow path of exhaust
gases is shown through the muffler 14 by a sequence of arrows. The
butterfly valve 38 is shown pivoted to a closed position, in which
exhaust gases are not allowed to flow through the passageway 30 in
the valve housing 26. More particularly, exhaust gases pass through
the first, second, and third chambers 94, 98, 102 as described
above with reference to FIG. 1. However, since the butterfly valve
38 is closed, exhaust gases in the third chamber 102 are directed
into the fourth chamber 106 via the plurality of second apertures
122. From the fourth chamber 106, the exhaust gases are directed
into the fifth chamber 110 via a plurality of third apertures 126
formed in the second sleeve 86. Further, the exhaust gases in the
fifth chamber 110 are directed into the sixth chamber 114 via a
plurality of fourth apertures 130 formed in the outlet tube 58.
From the sixth chamber 144, the exhaust gases may exit the muffler
14.
[0025] FIGS. 3 and 4 illustrate a second construction of a
motorcycle dynamic exhaust system 134 of the present invention. The
exhaust system 134 is a dual exhaust system 134 including a first
muffler 138 and a second muffler 142. In the illustrated
construction, the first muffler 138 is a conventional multi-chamber
muffler 138 while the second muffler 142 is a high-performance
single chamber muffler 142. However, alternate constructions of the
exhaust system 134 may utilize two high-performance single chamber
mufflers 142 or two conventional multi-chamber mufflers 138.
[0026] In the illustrated construction, a valve 22b is positioned
in the exhaust system 134 upstream of the second muffler 142. The
valve 22b is substantially similar to the valve 22a shown in FIGS.
1 and 2. As shown in FIGS, 3 and 4, the exhaust system 134 also
includes a first exhaust pipe 146 coupled to the first muffler 138,
and a second exhaust pipe 150 coupled to and merged with the first
exhaust pipe 146. The first and second exhaust pipes 146, 150 may
be connected to respective ehxuast ports of a motorcycle engine
(e.g., a V-twin engine, not shown) to receive exhaust gases. The
exhaust system 134 further includes a third exhaust pipe 154
coupled to and merged with the second exhaust pipe 150. The third
exhaust pipe 154 is also coupled to the valve 22b, which, in turn,
is coupled to the second muffler 142.
[0027] With reference to FIG. 3, a first flow path of exhaust gases
is shown through the exhaust system 134 by a sequence of arrows.
The butterfly valve 38 is shown pivoted to an open position, in
which unobstructed flow of exhaust gases is allowed through the
valve 22b. More particularly, exhaust gases may be redirected from
the second exhaust pipe 150 to the third exhaust pipe 154, thereby
utilizing both of the first and second mufflers 138, 142.
[0028] With reference to FIG. 4, a second flow path of exhaust
gases is shown through the exhaust system 134 by a sequence of
arrows. The butterfly valve 38 is shown pivoted to a closed
position, in which exhaust gases are not allowed to flow through
the valve 22b. More particularly, exhaust gases may not be
redirected from the second exhaust pipe 150 to the second muffler
142, thereby only utilizing the first muffler 138 in the exhaust
system 134.
[0029] FIGS. 5 and 6 illustrate a third construction of a
motorcycle dynamic exhaust system 158 of the present invention. The
exhaust system 158 includes a muffler 162 coupled to an exhaust
pipe (not shown) in a conventional manner. Although not shown, the
motorcycle may include a dual exhaust system utilizing a second
exhaust pipe and a second muffler.
[0030] Like the muffler 14 of FIGS. 1 and 2, the muffler 162
incorporates a valve 22c therein to direct the flow of exhaust
gases through the muffler 162. The valve 22c is substantially
similar to the valve 22a shown in FIGS. 1 and 2. As shown in FIGS.
5 and 6, the valve 22c is coupled to a first or inlet tube 166 of
the muffler 162. The inlet tube 166 is supported by a first wall
170 and a second wall 174, which divide the interior space of the
muffler 162 as bounded by an outer shell 178 into a first chamber
182, a second chamber 186, and a third chamber 190. The muffler 162
also includes a second or connecting tube 194 supported by the
first and second walls 170, 174 that communicates the first and
third chambers 182, 190. Further, the muffler 162 includes a third
or outlet tube 198 supported by the first and second walls 170, 174
that communicates the third chamber 190 with the atmosphere.
[0031] With reference to FIG. 5, a first flow path of exhaust gases
is shown through the exhaust system 158 by a sequence of arrows.
The butterfly valve 38 is shown pivoted to an open position, in
which unobstructed flow of exhaust gases is allowed through the
valve 22c. As such, exhaust gases from the inlet tube 166 are
allowed to discharge directly into the third chamber 190 (i.e.,
bypassing the first chamber 182), where the exhaust gases may flow
through the outlet tube 198 and exit the muffler 162.
[0032] With reference to FIG. 6, a second flow path of exhaust
gases is shown through the exhaust system 158 by a sequence of
arrows. The butterfly valve 38 is shown pivoted to a closed
position, in which exhaust gases are not allowed to flow through
the valve 22c. As such, exhaust gases are directed to the first
chamber 182 via the inlet tube 166, and to the third chamber 190
via the connecting tube 194. From the third chamber 190, the
exhaust gases may flow through the outlet tube 198 and exit the
muffler 162.
[0033] With reference to FIG. 7, a motorcycle 202 is shown that
incorporates the dynamic exhaust system 158 of FIGS. 5 and 6. FIG.
7 schematically illustrates the valve 22c positioned toward the
bottom of the motorcycle 202. However, in a motorcycle configured
to receive the exhaust systems 10, 134, the valves 22a, 22b may be
positioned relative to the motorcycle in a location appropriate
with the configuration of the respective exhaust systems 10, 134.
As such, the position of the valve 22c as shown in FIG. 7 is for
illustrative purposes only.
[0034] The illustrated motorcycle 202 is configured with an airbox
(the location of which is designated by reference numeral 206) in a
location on the motorcycle 202 typically associated with a fuel
tank. The airbox 206 houses conventional air intake components
(e.g., an air filter, not shown) for the engine. The airbox 206 is
also configured to receive an actuator 210 for opening and closing
the valve 22c of the exhaust system 158. The actuator 210 may be
mounted on top of the airbox 206 and protected by a cover (not
shown) covering the airbox 206.
[0035] The actuator 210 may be a conventional servo-motor having a
quadrant or lever 214 for pulling or releasing the cable 50. The
cable 50 is schematically illustrated as extending from the upper
portion of the motorcycle 202 to the bottom portion of the
motorcycle 202. However, the cable 50 may extend in any direction
on the motorcycle 202 depending on the location of the valve 22c in
the exhaust system 158. The cable 50 may also be substantially
hidden from view by routing the cable 50 through frame members of
the motorcycle 202 and/or hidden from view behind one or more
fairings or body panels of the motorcycle 202.
[0036] The actuator 210 is electrically connected to an engine
control unit 218 ("ECU") of the motorcycle 202. In addition to
controlling other functions of the motorcycle 202 (e.g., fuel
injection, engine timing, etc.), the ECU 218 is configured to
control operation of the actuator 210. In addition, a second cable
may be utilized to actuate a second valve.
[0037] Any of the dynamic exhaust systems 10, 134, 158 of FIGS. 1-6
may be utilized to alter the performance of the motorcycle's engine
and/or alter the noise emission characteristics of the motorcycle's
engine. With reference to FIG. 8, the engine's torque output is
shown as a function of engine speed (measured in revolutions per
minute, or RPM). More particularly, curve A illustrates the
engine's torque output when the exhaust gases are routed through
the first flow path of the exhaust system 158, in which the valve
22c is opened. Likewise, curve B illustrates the engine's torque
output when the exhaust gases are routed through the second flow
path of the exhaust system 158, in which the valve 22c is
closed.
[0038] As shown in FIG. 8, the engine's torque output may be
increased by opening the valve 22c during low engine speeds and
during high engine speeds. However, maintaining the valve 22c open
during mid-range engine speeds may also cause a decrease in torque
output compared to the engine's output when the valve 22c is
closed. Such a decrease in torque output may be caused by reversion
of the exhaust gases in the exhaust system 158.
[0039] The engine exhibits different operating characteristics, or
"torque characteristics," depending on the position (e.g., open or
closed) of the valve 22c. For example, when the valve 22c is in an
open position, the engine may exhibit a first torque characteristic
defined by curve A. Likewise, when the valve is in a closed
position, the engine may exhibit a second torque characteristic
defined by curve B. Selective actuation of the valve 22c between
open and closed positions may allow the engine to exhibit a third
torque characteristic defined by curve C that takes advantage of
the increase in torque output provided by the first operating
characteristic during low engine speeds and high engine speeds,
while also taking advantage of the torque output provided by the
second operating characteristic during mid-range engine speeds to
reduce the effects of the above-described reversion phenomena.
[0040] More particularly, for the engine to exhibit the third
torque characteristic and follow curve C, the valve 22c is
selectively controlled according to engine speed to cause the
engine to switch or transition between exhibiting the first torque
characteristic and exhibiting the second torque characteristic. For
example, the valve 22c may be actuated from an open position to a
closed position in a first crossover region, designated R1 in FIG.
8. The first crossover region R1 may be centered about a first
intersection or crossover point (designated P1) of curve A and
curve B. Crossover point P1 correlates with the engine speed at
which the engine outputs substantially the same amount of torque
whether it is exhibiting the first torque characteristic or the
second torque characteristic. As shown in FIG. 8, crossover point
P1 occurs at about 3800 RPM, and the crossover region R1 may extend
between about 3600 RPM and about 4000 RPM. However,
differently-configured engines may exhibit different torque
characteristics than those defined by curve A and curve B. As such,
crossover point P1 may occur at a higher or a lower engine speed
than 3800 RPM, and the crossover region R1 may be wider (i.e.,
encompass a greater range of engine speeds) or more narrow) i.e.,
encompass a smaller rang of engine speeds) than that illustrated in
FIG. 8.
[0041] For the engine to continue exhibiting the third torque
characteristic and following curve C, the valve 22c is actuated
from the closed position back to the open position in a second
crossover region, designated R1 in FIG. 8. The second crossover
region R2 may be centered about a second intersection or crossover
point (designated P2) of curve A and curve B. As shown in FIG. 8,
crossover point P2 occurs at about 5300 RPM, and the crossover
region R2 shown in FIG. 8, crossover point P2 occurs at about 5300
RPM, and the crossover region R2 may extend between about 5100 RPM
and about 5500 RPM. However, differently-configured engines may
exhibit different torque characteristics than those defined by
curve A and curve B. As such, crossover point P2 may occur at a
higher or a lower engine speed than 5100 RPM, and the crossover
region R2 may be wider (i.e., encompass a greater range of engine
speeds) or more narrow (i.e., encompass a smaller range of engine
speeds) than that illustrated in FIG. 8.
[0042] More particularly, the ECU 218 may be configured to trigger
the actuator 210, which in turn may actuate the valve 22c, when the
engine speed reaches the crossover points P1, P2 in the respective
crossover regions R1, R2. However, with respect to the crossover
region R1, the ECU 218 may trigger the actuator 210 at an engine
speed within the crossover region R1 but at a lower speed or a
higher speed than the crossover point P1. Likewise, with respect to
the crossover region R2, the ECU 218 may trigger the actuator 210
at an engine speed within the crossover region R2 but at a lower
speed or a higher speed than the crossover point P2.
[0043] The ECU 218 may also trigger the actuator 210 slightly
before the engine speed reaches the crossover point P1, or slightly
before the engine speed reaches the crossover point P2 to take into
account the mechanical lag associated with the actuator 210, cable
50, and valve 22c. In addition, the ECU 218 may be configured to
automatically make slighter corrections to the engine speed when
the valve 22c is actuated based upon input received by the ECU 218
from various engine or motorcycle sensors. Further, one or more
conditions may need to be satisfied in order for the ECU 218 to
trigger the actuator 210. For example, a condition that the engine
must be operating at 75% of full throttle or more may need to be
satisfied in order for the ECU 218 to trigger the actuator 210.
[0044] The ECU 218 may also be configured to trigger the actuator
210, and thus the valve 22c, according to the speed of the
motorcycle 202. It may be desirable to trigger the actuator 210
according to the speed of the motorcycle 202 to alter the noise
emission characteristics of the engine. For example, it may be
desirable to operate the engine below a pre-determined sound level
during mid-range cruising speeds (e.g., between 10 miles per hour
and 50 miles per hour, or MPH). As a result, the ECU 218 may be
configured to actuate the valve 22c from the open position to the
closed position at about 10 MPH. In the closed position, the valve
22c directs exhaust gases along a second flow path longer than the
first flow path to provide additional muffling of the sound pulses
of the exhaust gases. At about 50 MPH, the ECU 218 may be
configured to actuate the valve 22c back to the open position from
the closed position. In the open position, the valve 22c directs
exhaust gases along the first flow path to decrease the amount of
muffling of the sound pulses of the exhaust gases. The ECU 218 may
also be configured to trigger the actuator 210 at other motorcycle
speeds depending on the desired sound levels or noise emission
characteristics of the engine.
[0045] Various aspects of the invention are set forth in the
following claims.
* * * * *