Patent Grant
10724410
The present disclosure relates to exhaust systems for internal combustion engines associated with marine propulsion devices.
U.S. Pat. No. 9,359,981 discloses an outboard motor including a system for enhancement of a first subset of sounds having a desired frequency, and a method for modifying sounds produced by an air intake system for an internal combustion engine powering the outboard motor. The method includes collecting sounds emitted in an area proximate a throttle body of the engine. A first subset of the collected sounds, which have frequencies within desired frequency range, is then amplified. The amplified first subset of sounds is then transmitted to an area outside a cowl covering the engine.
U.S. Pat. No. 9,376,195 discloses an outboard motor comprising an engine having an exhaust gas discharge opening, a midsection housing coupled below and supporting the engine, and an exhaust pipe having an exhaust inlet in fluid communication with the exhaust gas discharge opening. The exhaust pipe extends downwardly to a primary exhaust outlet. An idle relief port in the exhaust pipe is located in a fluid path between the exhaust inlet and the primary exhaust outlet. A sound-attenuating plenum chamber has an interior that is in fluid communication with an interior of the exhaust pipe by way of the idle relief port. The plenum chamber is a separate component that is exterior to the midsection housing, and exhaust gas flows from the interior of the exhaust pipe to the interior of the plenum chamber without first flowing through the midsection housing.
U.S. Pat. No. 9,944,376 discloses exhaust systems for outboard marine engines that are configured to propel a marine vessel in a body of water. An intermediate exhaust conduit is configured to receive the exhaust gas from the primary exhaust conduit. A primary muffler receives the exhaust gas from a intermediate exhaust conduit. A secondary muffler receives the exhaust gas from the primary muffler. An idle relief outlet discharges the exhaust gas from the secondary muffler to atmosphere. A bypass valve is positionable into an open position wherein the exhaust gas is permitted to bypass the secondary muffler and flow from the primary muffler to the idle relief outlet and into a closed position wherein the exhaust gas is not permitted to bypass the secondary muffler and instead flows from the primary muffler to the idle relief outlet via the secondary muffler.
U.S. Pat. No. 10,180,121 discloses an outboard motor including an internal combustion engine and a cowl covering the engine. An air vent allows intake air into the cowl, an air intake duct routes the intake air from the air vent to the engine, and a throttle body meters flow of the intake air from the air intake duct into the engine. A sound enhancement device is located proximate the throttle body. A sound duct is provided, and has an inlet end located proximate the sound enhancement device and an outlet end located proximate an outer surface of the cowl. The sound enhancement device is tuned to amplify a first subset of sounds having a desired frequency that are emitted from the throttle body, and the sound duct transmits the amplified sounds to an area outside the cowl. A method for modifying sounds produced by an air intake system of an outboard motor is also provided.
U.S. Pat. No. 9,909,545 discloses an outboard motor including an internal combustion engine powering the outboard motor and a cowl covering the engine and having a vent allowing air under the cowl. A throttle body meters flow of the air into the engine and an intake structure downstream of the throttle body delivers the metered airflow to one or more combustion chambers in a cylinder block of the engine. A sound enhancement assembly in acoustic communication with the intake structure collects sounds emitted by the engine. The sound enhancement assembly is configured to amplify a subset of the collected sounds that have frequencies within a desired frequency range. A method for modifying sounds produced by an air intake system of an internal combustion engine powering an outboard motor is also disclosed. The method includes positioning a sound enhancement assembly in acoustic communication with an air intake passageway located downstream of the engine's throttle body.
The above patents and patent applications are hereby incorporated by reference herein in their entireties.
This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
One example of the present disclosure includes a marine propulsion device comprising an internal combustion engine powering the marine propulsion device and an engine compartment containing the engine. A primary exhaust passageway routes exhaust gas away from the engine and out of the engine compartment. A sound enhancement assembly communicates with the primary exhaust passageway. The sound enhancement assembly includes a sound enhancement device tuned to amplify exhaust sounds of a predetermined frequency and a sound duct downstream of the sound enhancement device that transmits the amplified exhaust sounds to an area outside the engine compartment. The sound enhancement device isolates the sound duct from the exhaust gas.
According to another example of the present disclosure, a method for modifying sounds produced by an exhaust system of an internal combustion engine powering a marine propulsion device is disclosed. The method comprises providing a sound enhancement device proximate a primary exhaust passageway that routes exhaust gas away from the engine; routing the exhaust gas from the primary exhaust passageway to the sound enhancement device; and configuring the sound enhancement device to amplify exhaust sounds of a predetermined frequency. The method also includes routing a sound duct from the sound enhancement device to an area outside an engine compartment containing the engine such that the amplified exhaust sounds can be transmitted as sound pressure pulses through the sound duct to the area outside the engine compartment. The method also includes preventing the exhaust gas from flowing through the sound duct.
The present disclosure is described with reference to the following Figures. The same numbers are used throughout the Figures to reference like features and like components.
In the present description, certain terms have been used for brevity, clarity and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed.
Product noise requirements and/or expectations of a given marine propulsion device can vary greatly depending on the application. For example, performance boaters may desire a louder and/or more powerful exhaust sound quality than recreational boaters. However, expectations for sound quality and refinement are universal, and dictated in some geographical areas by law, regardless of the noise level expectations of the customer. The system and method of the present disclosure enhance the powerful, desirable sound characteristics of a marine propulsion device without sacrificing the requirements and/or expectations for refinement of unpleasant sound. For example, because at above-idle engine speeds exhaust sounds are usually muffled as they pass through the gearcase cavity C and underwater outlet D, the present inventors have developed a system and method for amplifying exhaust sounds in a controllable manner at mid to high engine speeds, with minimal impact on engine performance. The present inventors have also developed a system and method that allow for tuned amplification of exhaust sounds when the engine is at idle or near-idle speeds, in contrast to the muffled system shown in
The present inventors have determined through research and development that conventional exhaust systems for marine propulsion devices do not adequately allow an operator to actively tune the sound emanating from the exhaust system A. More specifically, the present inventors have determined that it would be desirable to provide actively tunable exhaust systems for marine propulsion devices, wherein the operator is given the ability to select between a variety of exhaust sounds and to amplify the selected sounds. The present disclosure is a result of the inventors' research and experimentation directed towards providing the operator of a marine propulsion device with the ability to select a particular sound quality of the exhaust system. By way of the present system and method, an operator is able to increase the exhaust noise contribution throughout the entire engine speed range, rather than suppress it during idle/low speed operation as does a muffler E in a traditional idle relief circuit.
A sound enhancement assembly 18 communicates with the primary exhaust passageway 16. The sound enhancement assembly 18 includes a sound enhancement device 20 tuned to amplify exhaust sounds of a predetermined frequency, as will be described further herein below. The sound enhancement assembly 18 also includes a sound duct 22 downstream of the sound enhancement device 20 that transmits the amplified exhaust sounds to an area outside the engine compartment 14, such as outside the cowl for an outboard or outside the hull for a stern drive. The sound enhancement device 20 isolates the sound duct 22 from the exhaust gas in the primary exhaust passageway 16, as will also be described further herein below. A sound control valve 24 upstream of the sound enhancement device 20 controls provision of the exhaust gas to the sound enhancement device 20. In one example, the sound control valve 24 is a butterfly valve, as shown here. The sound enhancement assembly 18 also includes a drive pipe 26 that connects the sound control valve 24 to the sound enhancement device 20. In this example, the sound control valve 24 is connected directly to the primary exhaust passageway 16.
More specifically, the sound enhancement assembly 18 communicates via the sound control valve 24 with a lower portion 16a of the primary exhaust passageway 16 that carries exhaust gas that has been cooled by cooling water, which is sprayed into the primary exhaust passageway 16 itself and/or surrounds the primary exhaust passageway 16 in a water jacket. The exhaust gas in the lower portion 16a is sometimes referred to as “cooled” or “wet” exhaust, in contrast to the “hot” or “dry” exhaust present in an upper portion 16b of the primary exhaust passageway 16. Note that although the former may be called “wet” exhaust, the inlet to the sound enhancement assembly 18 may be placed in a location where the exhaust that enters it does not actually have water droplets in it, in order to maintain the structural and functional integrity of the sound enhancement assembly 18.
As shown, the membrane housing 20a has an open interior 20b, which in this example is cylindrical. A flexible membrane 20c extends transversely across the open interior 20b of the membrane housing 20a and isolates the sound duct 22 from the exhaust gas in the drive pipe 26. The sound enhancement device 20 is tuned to amplify exhaust sounds of a predetermined desired frequency that are caused by pulsations of exhaust gas within the exhaust system 11. The sound duct 22 transmits the amplified exhaust sounds to an area outside the engine compartment 14. The sound duct 22 can be made of plastic or another material that is suitable for a marine environment. The sound duct 22 can have a cross-sectional shape of a circle (as shown), an oval, a rectangle, or another type of polygon, according to the desired sound effect and design constraints imposed by the remainder of the marine propulsion device 10. Several different characteristics, structures, and designs for the sound duct 22 are available. For instance, the shape and diameter of the sound duct 22 can be selected specifically to achieve desired enhancement of sound.
The sound enhancement device 20 acts as a passive speaker that is tuned to amplify exhaust sounds of the predetermined frequency. The sound enhancement device 20 adjusts the spectral frequency (sound amplitude vs. frequency) of sounds having the predetermined frequency without the use of active components such as, for example, electronic amplifiers. This predetermined frequency can be defined in any way desired by the manufacturer, installer, or operator of the marine propulsion device 10. For example, the predetermined frequency may include sounds that produce what might be considered a pleasant “rumble” that conveys the power of the engine 12 to the operator of the vessel. The sound enhancement device 20 can be tuned to amplify this pleasant rumble such that the operator can hear it better. Of note is that the primary exhaust passageway 16 is separate and distinct from the passageway defined by the sound duct 22. The primary exhaust passageway 16 conducts exhaust gas, while the sound duct 22 conducts sound pressure pulses to the area outside the engine compartment 14. The sound enhancement device 20 separates these two passageways from one another, and does not allow air to pass between the two passageways. Rather, it is sound that is transmitted by the sound duct 22. Thus, the sound enhancement assembly 18 can be provided as an add-on or aftermarket feature that does not affect or interfere with the primary exhaust flow. The present arrangement is therefore different from a through-cowl (for an outboard) or through-hull (for a stern drive) exhaust system, in that exhaust sounds can be provided to the atmosphere without exhaust gas also being provided to the atmosphere.
In one example, the sound enhancement device 20 comprises the membrane 20c that extends generally transversely across the open interior 20b of the membrane housing 20a. In another example, the membrane 20c can extend across an aperture within a single pipe that defines both the drive pipe 26 and the sound duct 22. The membrane 20c can have any sort of shape that will fill the cross-sectional shape of the membrane housing 20a, and its outer edges can be sealed along an inner perimeter of the open interior 20b so as to isolate the sound duct 22 from contact with exhaust gas. Thus, as noted, the sound duct 22 is not a functional part of the exhaust system 11 and does not supply exhaust to the atmosphere. Retaining rings can be provided on one or both sides of the membrane 20c to hold it within the open interior 20b, which can be provided with an inner flange to hold the retaining rings.
The membrane 20c may be made out of any sort of flexible or elastomeric substance, and in one example is a disc made out of rubber. A stiffness of the membrane 20c can be changed (tuned) in order to provide a desired amount of amplification of sounds having the predetermined frequency and/or to change the frequency of sounds that will be amplified. The stiffness of the membrane 20c can be varied by stretching the membrane 20c tighter or allowing the membrane 20c to be looser as it spans the open interior 20b. Another way in which the acoustic flexure properties of the membrane 20c may be tuned or adjusted is by varying the thickness (and therefore mass and stiffness) of the membrane 20c. Additionally, the composition of the membrane 20c itself and/or products that are applied to the membrane 20c can cause it to exhibit different characteristics upon application of sound waves. Because the sound enhancement assembly 18 (including drive pipe 26, sound duct 22, and sound enhancement device 20) is passive, it relies on acoustic excitation of components of the sound enhancement device 20 by exhaust sounds to provide amplification. As noted above, the inlet to the sound enhancement assembly 18 may be along the path of cooled exhaust; this prevents the membrane 21c from being compromised by heat, which is helpful in the instance where the membrane 21c is made from rubber.
In alternative embodiments, the sound enhancement device 20 includes a membrane 21c made of plastic or of a thin metal sheet attached to a spring that can be tuned (by selection of the spring or by adjusting the spring constant by way of an electrical current from a controller 35, as will be described herein below) to achieve amplification of exhaust sounds having the desired predetermined frequency. The sound enhancement device 20 may have components alternative to the membrane 21c, such as a trumpet or a flexible bellows with an end cap.
An outlet end 72 of the sound duct 22 is located outside of the engine compartment 14, such as outside the chaps (lower cowl) on a fore side of an outboard motor, or outside the vessel hull for a stern drive, so as to deliver the amplified exhaust sounds to an area that is closest to the operator. In one example, the entire sound enhancement assembly 18 except for the outlet end 72 is placed underneath the chaps (lower cowl) of an outboard motor, thus hiding it from view and also avoiding packaging/space conflicts with powerhead components in the upper cowl area. In contrast, exhaust gas exiting the idle relief outlet 52 can be directed to a side or the rear of the marine propulsion device 10, as an operator would not want exhaust gas emitted in his/her direction. Non-amplified exhaust sounds, which have frequencies other than within the predetermined frequency range, will also be emitted via the idle relief outlet 52. In fact, in the instance where an idle relief muffler 34 is included (see
As alluded to, the exhaust systems 9, 11 (and 13, 15,
Note that components of the sound enhancement assembly 18 described with respect to
Returning to
In other examples, instead of including a sound control valve 24, the sound enhancement assembly 18 may include a moveable contact member supported by and within the membrane housing 20a, such as an arm or disc, which can be moved into or out of contact with the membrane 20c, thereby limiting or preventing or allowing movement of the membrane 20c, respectively. When the contact member is in contact with the membrane 20c, movement or elastic deformation (and hence amplification of sound) is limited or prevented. This feature provides an alternative way to turn the sound amplification on or off, as the contact member may also be in communication with the operator input device 31 and/or the controller 35.
The noted controller 35 can be programmable and include a processor and a memory. The controller 35 can be located anywhere in the system and/or located remote from the system and can communicate with various components of the marine vessel via wired and/or wireless links. In certain examples, the controller 35 is an engine control unit (ECU) that is also configured to control the internal combustion engine and/or other components of the marine propulsion device 10. Although
The controller 35 can be programmed to automatically tune the sound enhancement device 20 with or without an initial input from the operator input device 31. For example, the controller 35 may open the sound control valve 24 to increasingly more open positions as the speed of the engine 12 or the marine vessel increases. Alternatively, the controller 35 may open the sound control valve 24 only when the engine speed is within a specific RPM range predefined and saved in the memory. In the example in which a contact member is provided for contacting the membrane 21c, the controller 35 may move the contact member out of contact with the membrane 21c when the engine 12 is operated in the RPM range. In these ways, the sound enhancement device 20 can be designed as an actively tunable device that controls the amount of sound amplification as function of engine and/or vessel speed.
The controller 35 may additionally or alternatively be programmed to change physical characteristics of the sound enhancement device 20 by way of signal communication therewith. The controller 35 can change the device's physical characteristics, for example, as a function of engine or vessel speed or in response to input via the operator input device 31. By way of non-limiting examples, the controller 35 may be in electrical communication with a shape memory alloy wire running through or along the spring in the example in which the sound enhancement device 20 is a spring/mass system, wherein provision of different electrical currents through the wire change the stiffness of the spring and thus the spectral frequency of exhaust sound that will be amplified. In another example, in the example in which the sound enhancement device 20 has a flexible bellows-like housing, the controller 35 may provide a current to a shape memory alloy wire or to a mechanical device that causes the bellows to lengthen or contract, thereby changing the spectral frequency of exhaust sound that will be amplified. Other mechanical or electrical devices may be provided that change the tautness of the membrane 21c across the membrane housing 21a. In these exemplary ways, not only is tuning of the amount of amplification of the sound enhancement assembly 18 possible by way of the sound control valve 24 and/or contact member, but tuning of the frequency range that will be amplified is also possible.
Optionally, an indicator device 33 can be provided that is configured to indicate to the operator a current position of the sound control valve 24 or contact member. The operator input device 31 and/or indicator device 33 can be located remotely from the marine propulsion device 10, for example at the helm of the marine vessel, or even remotely from the marine vessel. The type of indicator device 33 can vary. In certain non-limiting examples, the indicator device 33 can include a video or touch screen, and/or flashing lights, and/or the like. The indicator device 33 can be electronically controlled by the controller 35 to indicate to the operator the current position of the sound control valve 24 or contact member.
Via the operator input device 31, the exemplary system shown in
In this example, the sound enhancement assembly 18 communicates with the primary exhaust passageway 16 via the idle relief assembly 40. More specifically, the primary muffler 44 has an inlet 54 coupled to the primary exhaust passageway 16 by way of upstream end 48 of intermediate exhaust conduit 42. The sound enhancement assembly 18 is connected to the primary muffler 44 via the sound control valve 24, and the sound control valve 24 controls provision of the exhaust gas from the primary muffler 44 to the sound enhancement assembly 18. The intermediate exhaust conduit 42 is also coupled to an outlet 56 of the primary muffler 44 and includes a second downstream end 60 that leads to the idle relief outlet 52 configured to discharge the exhaust gas to the area outside the engine compartment. An idle relief control valve 58 controls flow of the exhaust gas from the muffler outlet 56 through the second downstream end 60 of the intermediate exhaust conduit 42 to the idle relief outlet 52.
The idle relief control valve 58 is coupled to and/or positioned in the intermediate exhaust conduit 42 and is positionable into an open position, shown in
In certain examples, the idle relief control valve 58 is also positionable into one or more intermediate position(s) wherein, compared to the open position, at an idle speed of the internal combustion engine, a reduced amount of exhaust gas is permitted to bypass the secondary muffler 46 and flow from the primary muffler 44 to the idle relief outlet 52. In other words, at an idle speed of the internal combustion engine, in the intermediate position(s), a portion of the exhaust gas is permitted to bypass the secondary muffler 46 and a portion of the exhaust gas is forced to flow through the secondary muffler 46. Both portions are discharged via the idle relief outlet 52. In certain examples, the idle relief control valve 58 is located at the second downstream end 60 of the intermediate exhaust conduit 42 at a location that is on an opposite side of an adapter plate 62 of the marine propulsion device relative to the primary and secondary mufflers 44, 46, although such positioning is not shown herein.
When the idle relief control valve 58 is in the closed position, the exhaust system 13 forms a dual muffler circuit, and when the idle relief control valve 58 is in the open position, the exhaust system 13 forms a single muffler circuit. The exhaust system 13 operates in a “quiet mode” when the idle relief control valve 58 is in the closed position and the exhaust gas is routed through the more restrictive dual muffler circuit. The exhaust system 13 operates in a relatively louder “sport mode” when the idle relief control valve 58 is in the open position and the exhaust gas is routed through the less restrictive single muffler circuit.
Note that the idle relief control valve 58 can also be controlled by an operator input device, which can be the same as or distinct from the operator input device 31 described with respect to
Placement of the sound enhancement assembly 18 in this location means that the combined sound and idle relief control valve 64 controls not only the release of air through the idle relief assembly 40 in the “quiet mode” or the “sport mode”, but also controls the sound pressure level entering the sound enhancement assembly 18 at the same time. When the combined sound and idle relief control valve 64 is closed, as shown in
In contrast, when the combined sound and idle relief control valve 64 is open, as shown in
As shown at box 104, the method includes configuring the sound enhancement device 20 to amplify exhaust sounds of a predetermined frequency. This may include any or all of configuring the size, shape, and/or mechanical properties of the sound enhancement device 20, as described hereinabove. The method also includes routing a sound duct 22 from the sound enhancement device 20 to an area outside an engine compartment 14 containing the engine 12 such that the amplified exhaust sounds can be transmitted as sound pressure pulses through the sound duct 22 to the area outside the engine compartment 14, as shown at box 106. As shown at box 108, the method also includes preventing the exhaust gas from flowing through the sound duct 22. This can be done by way of, for example, ensuring that the membrane 20c provides a fluid-tight seal across the open interior 20b of the membrane housing 20a.
The method may also include providing an idle relief assembly 40 in communication with the primary exhaust passageway 16, wherein the idle relief assembly 40 routes the exhaust gas from the primary exhaust passageway 16 to the sound enhancement device 20. The idle relief assembly 40 may comprise a muffler 44 having an inlet 54 coupled to the primary exhaust passageway 16, and the sound control valve 24 may control provision of the exhaust sounds from the muffler 44 to the sound enhancement device 20. The idle relief assembly 40 may further comprise an intermediate exhaust conduit 42 coupled to an outlet 56 of the muffler 44 and leading to an idle relief outlet 52 configured to discharge the exhaust gas to the area outside the engine compartment 14.
The method may also include selecting a level of amplification of the exhaust sounds by way of providing a sound control valve 24, 64 upstream of the sound enhancement device 20 that controls provision of the exhaust gas to the sound enhancement device 20. An operator input device 31 can be provided via which an operator can control the sound control valve 24, 64. In one example, the sound control valve is a combined sound and idle relief control valve 64 that controls flow of the exhaust gas from the muffler 44 through the intermediate exhaust conduit 42 to the idle relief outlet 52, and the method further comprises connecting the sound enhancement device 20 to the intermediate exhaust conduit 42 downstream of the combined sound and idle relief control valve 64. See
In the above description, certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. The different systems and method steps described herein may be used alone or in combination with other systems and methods. It is to be expected that various equivalents, alternatives and modifications are possible within the scope of the appended claims. Each limitation in the appended claims is intended to invoke interpretation under 35 U.S.C. § 112(f), only if the terms “means for” or “step for” are explicitly recited in the respective limitation.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1824737 | Johnson et al. | Sep 1931 | A |
| 3967446 | Harralson et al. | Jul 1976 | A |
| 4522602 | Okazaki | Jun 1985 | A |
| 4601666 | Wood | Jul 1986 | A |
| 4668199 | Freund et al. | May 1987 | A |
| 4734070 | Mondek | Mar 1988 | A |
| 4778029 | Thornburgh | Oct 1988 | A |
| 4846300 | Boda | Jul 1989 | A |
| 4887692 | Outani et al. | Dec 1989 | A |
| 4952182 | Curtis et al. | Aug 1990 | A |
| 5083538 | Hubbell | Jan 1992 | A |
| 5348500 | Lassanske | Sep 1994 | A |
| 5954554 | Bates | Sep 1999 | A |
| 6299496 | Griffiths | Oct 2001 | B1 |
| 6647956 | Sharpton | Nov 2003 | B1 |
| 6722467 | Kusche et al. | Apr 2004 | B1 |
| 6732509 | Shiga | May 2004 | B2 |
| 6830024 | Kodweiss et al. | Dec 2004 | B2 |
| 6932189 | Helber et al. | Aug 2005 | B2 |
| 7021262 | Belter et al. | Apr 2006 | B1 |
| 7188703 | Hofmann et al. | Mar 2007 | B2 |
| 7299783 | Broman et al. | Nov 2007 | B1 |
| 7350496 | Nakayama et al. | Apr 2008 | B2 |
| 7353791 | Sasaki | Apr 2008 | B2 |
| 7448353 | Shinada et al. | Nov 2008 | B2 |
| 7506626 | Sasaki et al. | Mar 2009 | B2 |
| 7621370 | Abe et al. | Nov 2009 | B2 |
| 7845466 | Kostun et al. | Dec 2010 | B2 |
| RE42490 | Takeuchi et al. | Jun 2011 | E |
| 7967106 | Ross et al. | Jun 2011 | B2 |
| 8011469 | Olson | Sep 2011 | B2 |
| 8127888 | Mah | Mar 2012 | B1 |
| 8322486 | Ohta et al. | Dec 2012 | B2 |
| 8384528 | McCarthy | Feb 2013 | B2 |
| 8579077 | Ahn et al. | Nov 2013 | B2 |
| 8651906 | Morton | Feb 2014 | B1 |
| 8666088 | Khami et al. | Mar 2014 | B2 |
| 8684132 | Muller et al. | Apr 2014 | B2 |
| 8776755 | Muller et al. | Jul 2014 | B2 |
| 8876566 | Hilbert et al. | Nov 2014 | B1 |
| 8905187 | Schorn et al. | Dec 2014 | B2 |
| 9025786 | Luecking et al. | May 2015 | B2 |
| 9051041 | Litjens et al. | Jun 2015 | B2 |
| 9359981 | Waisanen | Jun 2016 | B1 |
| 9365273 | Davis et al. | Jun 2016 | B2 |
| 9376191 | Jaszewski | Jun 2016 | B1 |
| 9376194 | Jensen | Jun 2016 | B1 |
| 9376195 | Jaszewski et al. | Jun 2016 | B1 |
| 9386366 | Koch et al. | Jul 2016 | B2 |
| 9422843 | Barrett et al. | Aug 2016 | B2 |
| 9429117 | Takahashi et al. | Aug 2016 | B2 |
| 9462363 | Wirth et al. | Oct 2016 | B2 |
| 9677438 | Holbrook | Jun 2017 | B2 |
| 20050121254 | Hofmann | Jun 2005 | A1 |
| 20050121255 | Hofmann | Jun 2005 | A1 |
| 20050133300 | Hofmann | Jun 2005 | A1 |
| 20070054569 | Murai et al. | Mar 2007 | A1 |
| 20070261387 | Maybeck | Nov 2007 | A1 |
| 20070292281 | Sasaki et al. | Dec 2007 | A1 |
| 20090078497 | Ishizuka et al. | Mar 2009 | A1 |
| 20110147116 | Olson | Jun 2011 | A1 |
| 20140055258 | Grosse-Budde | Feb 2014 | A1 |
| 20170350287 | Pompucci | Dec 2017 | A1 |
| Number | Date | Country |
|---|---|---|
| 1358400 | Nov 2003 | EP |
| 2006069277 | Mar 2006 | JP |
| Entry |
|---|
| K.C. Colwell, Faking It: Engine-Sound Enhancement Explained, Car and Driver Website, Apr. 2012, available at http://www.caranddriver.com/features/faking-it-engine-sound-enhancement-explained-tech-dept, 7 pages. |
| Waisanen et al., Outboard Motor With Sound Enhancement Device and Method for Modifying Sounds Produced by Air Intake System of an Outboard Motor, Unpublished U.S. Appl. No. 15/091,007, filed Apr. 5, 2016. |
| Waisanen et al., “Actively Tunable Exhaust Systems for Outboard Marine Engines,” Unpublished U.S. Appl. No. 15/088,656, filed Apr. 1, 2016. |
| Waisanen et al., “Outboard Motor With Sound Enhancement Device and Method for Modifying Sounds Produced by Air Intake System of an Outboard Motor,” Unpublished U.S. Appl. No. 15/219,617, filed Jul. 26, 2016. |
