Noise reduction technique for snowmobiles
An air intake that reduces the transmission of noise from an internal combustion engine while maintaining high air intake flow rates. The air intake has a duct for delivering air to an internal combustion engine, and resonator volumes in communication with the inside of the duct, to selectively attenuate engine noise at certain frequencies and across certain frequency ranges.
The invention relates to air intake systems for recreational vehicles such as snowmobiles, all terrain vehicles (ATVs), and other similar vehicles. More particularly, the invention relates to air intake systems that reduce the transmission of noise from the engines of such vehicles.
BACKGROUNDSnowmobiles are popular land vehicles used as transportation vehicles or as recreational vehicles in cold and snowy conditions. Snowmobiles typically employ an internal combustion engine to drive an endless track to provide propulsion. Noise generated by snowmobile engines can be emitted from either the exhaust or the air intake of the engine, detracting from the enjoyment of the user, as well as potentially creating an environmental nuisance. Methods of addressing exhaust noise are known in the art. Methods of reducing air intake noise exist, but such methods tend to reduce air flow to the engine, thereby reducing engine efficiency and hence performance. Further, such methods do not adequately address the need to suppress noise energy at particular frequencies associated with snowmobile engines. Therefore, a need exists to reduce the amount of engine noise that is emitted from the air intake of snowmobile engines, particularly at certain frequencies, while maintaining a high amount of air flow to the engine to maximize engine performance.
BRIEF SUMMARY OF THE INVENTIONSome embodiments of the invention provide an air intake for a snowmobile that incorporates frequency selective noise attenuation while maintaining high air flow to the snowmobile engine.
BRIEF DESCRIPTION OF THE DRAWINGS
The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings depict selected embodiments and are not intended to limit the scope of the invention. It will be understood that embodiments shown in the drawings and described above are merely for illustrative purposes, and are not intended to limit the scope of the invention as defined in the claims that follow.
A snowmobile 10 in accordance with some embodiments of the invention is shown in
The chassis front portion 14 may be suitable for mounting the pair of steerable skis 24 and supporting the body assembly 26. The body assembly 26 may contain the engine 18. A steering post 30 is operatively connected to the pair of skis 24. Means for rotating the steering post 30 to effect steering may be provided, and the means for rotating may be supported by the steering post 30. In some embodiments, the means for rotating may include a steering control, such as handlebars 32, supported by the steering post 30.
Two of the resonator volumes can form Helmholtz resonators for the air intake duct 100 by providing fluid communication through openings 120, 130 (see
In some embodiments, such as the one shown in
FIGS. 8(a) and 8(b) are two views of Helmholtz resonator opening 120. Similarly, FIGS. 9(a) and 9(b) provide views of Helmholtz resonator opening 130. For illustrative purposes only, the relative lengths of the openings 120, 130 is shown. The longer “neck” portion of opening 120 (relative to opening 130) would tend to make the Helmholtz resonator associated with opening 120 attenuate noise energy at lower frequencies than the Helmholtz resonator associated with opening 130, assuming other factors (such as the volume of the respective resonator volumes 150, 154, and the diameter of openings 120, 130) are held constant.
Thus, embodiments of the Noise Reduction Technique For Snowmobiles are disclosed. One skilled in the art will appreciate that the technique can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the invention is limited only by the claims that follow.
Claims
1. An air intake for an internal combustion engine, comprising:
- a duct for directing air intake flow through an interior space in the duct towards an engine for use in internal combustion, the duct having an inlet and an outlet;
- a housing surrounding the duct and defining an enclosed space between the duct and the housing; and
- baffle plates extending outwardly from the duct to the housing and dividing the enclosed space into a plurality of resonator volumes, the duct having openings in walls of the duct, the openings establishing fluid communication paths between the interior space of the duct and the resonator volumes to form at least two Helmholtz resonators to attenuate sound pressure energy emanating from the internal combustion engine, the at least two Helmholtz resonators being insulated from each other.
2. The air intake of claim 1, wherein the at least two Helmholtz resonators are separated by at least one of the resonator volumes to insulate the at least two Helmholtz resonators from each other.
3. The air intake of claim 1, wherein a portion of the duct is perforated, the perforations establishing fluid communication paths between the interior space of the duct and at least one of the resonator volumes to form at least one sleeve resonator to attenuate sound pressure energy emanating from the internal combustion engine.
4. The air intake of claim 3, wherein the at least one sleeve resonator is positioned between the at least two Helmholtz resonators to insulate the at least two Helmholtz resonators from each other.
5. The air intake of claim 1, wherein the at least two Helmholtz resonators attenuate sound of different wavelengths.
6. The air intake of claim 1, wherein the at least two Helmholtz resonators attenuate sound under 1000 Hz.
7. The air intake of claim 1, wherein at least one of the openings for the at least two Helmholtz resonators faces in a different direction.
8. An air intake for an internal combustion engine, comprising:
- a duct for directing air intake flow through an interior space in the duct towards an engine for use in internal combustion, the duct having an inlet and an outlet;
- the duct having openings in walls of the duct, the openings establishing fluid communication paths between the interior space of the duct and enclosed resonator volumes to form two separate Helmholtz resonators to attenuate sound pressure energy emanating from the internal combustion engine, the two Helmholtz resonators being insulated from each other.
9. The air intake of claim 8, wherein the two Helmholtz resonators are separated by another resonator volume to insulate the two Helmholtz resonators from each other.
10. The air intake of claim 8, wherein a portion of the duct is perforated, the perforations establishing fluid communication paths between the interior space of the duct and at least one of the resonator volumes to form at least one sleeve resonator that attenuates sound pressure energy emanating from the internal combustion engine.
11. The air intake of claim 10, wherein the at least one sleeve resonator is positioned between the two Helmholtz resonators to insulate the two Helmholtz resonators from each other.
12. The air intake of claim 8, wherein the two Helmholtz resonators are spaced apart a sufficient distance to insulate the two Helmholtz resonators from each other.
13. The air intake of claim 8, further including a housing at least partially surrounding the duct and forming the enclosed resonator volumes between the duct and the housing.
14. The air intake of claim 8, wherein the enclosed resonator volumes forming the two Helmholtz resonators are formed in part by the outside surface of the duct.
15. The air intake of claim 1, wherein each of the at least two Helmholtz resonators is adapted to attenuate sound pressure energy at or around a particular frequency.
16. The air intake of claim 15, wherein two or more baffle plates extend between the wall of the duct and the housing, dividing the enclosed space between the wall of the duct and the housing into three resonator volumes, and wherein the air intake includes two Helmholtz resonators.
17. The air intake of claim 16, wherein the two Helmholtz resonators include a first resonator volume located nearest the air intake inlet and a third resonator volume located nearest the air intake outlet.
18. The air intake of claim 17, further comprising at least one perforated area in the wall of the duct, wherein the at least one perforated area places the duct in fluid communication with a second resonator volume positioned between the first and third resonator volumes, forming a perforated sleeve resonator adapted to attenuate sound pressure energy emanating from the internal combustion engine over a range of frequencies.
19. The air intake of claim 17, wherein the two Helmholtz resonators are adapted to attenuate sound pressure energy emanating from the internal combustion engine at frequencies at or around 125 hertz and 250 hertz.
20. The air intake of claim 18, wherein the perforated sleeve resonator comprises two or more perforated areas.
21. The air intake of claim 18, wherein the duct and the housing form a continuous air intake flow path for maximizing air flow and improving engine efficiency.
22. The air intake of claim 18, wherein the two Helmholtz resonators are adapted to attenuate sound pressure energy emanating from the internal combustion engine at frequencies at or around 125 hertz and 250 hertz.
23. The air intake of claim 22, wherein the Helmholtz resonator adapted to attenuate sound pressure energy at frequencies at or around 125 hertz includes the first resonator volume and the Helmholtz resonator adapted to attenuate sound pressure energy at frequencies at or around 250 hertz includes the third resonator volume.
24. The air intake of claim 23, wherein the perforated sleeve resonator is adapted to attenuate sound pressure energy emanating from the internal combustion engine over a frequency range from about 275 hertz to about 1000 hertz.
25. The air intake of claim 23, wherein the perforated sleeve resonator is adapted to attenuate sound pressure energy emanating from the internal combustion engine over a frequency range from about 300 hertz to about 600 hertz.
26. A snowmobile having skis, an endless track propulsion mechanism, a steering column for turning the skis, an internal combustion engine for driving the endless track, and an air intake system for delivering air to the internal combustion engine, the air intake system comprising:
- a duct for directing air intake flow through an interior space in the duct towards an engine for use in internal combustion, the duct having an inlet and an outlet;
- a housing surrounding the duct and defining an enclosed space between the duct and the housing; and
- baffle plates extending outwardly from the duct to the housing and dividing the enclosed space into a plurality of resonator volumes, the duct having openings in walls of the duct, the openings establishing fluid communication paths between the interior space of the duct and at least two of the resonator volumes to form at least two Helmholtz resonators to attenuate sound pressure energy emanating from the internal combustion engine, the duct further having a perforated portion establishing fluid communication between the interior space of the duct and at least one of the resonator volumes to form at least one sleeve resonator that attenuates sound pressure energy emanating from the internal combustion engine, wherein the at least two Helmholtz resonators are insulated from each other by the at least one sleeve resonator.
Type: Application
Filed: Aug 12, 2004
Publication Date: Feb 16, 2006
Inventor: James Vizanko (Warroad, MN)
Application Number: 10/916,719
International Classification: F01N 1/08 (20060101);