Patent Application
20200386132
The present disclosure relates generally to sound attenuation devices for use with various types of engines, and, more specifically, the present disclosure relates to a muffler that is consistently effective over a broad range of frequencies and operating conditions.
Engines, including internal combustion engines and gas turbine engines, produce exhaust gases that must be vented from the engine system. Typically, the exhaust gases travel from the engine through an exhaust system before being expelled to the atmosphere. As the exhaust gases travel at high velocities through exhaust pipes and other system components, the gases produce noise emissions that can reach high decibel (dB) levels. In work machine applications, such as excavators, track type tractors, and the like, exhaust sounds can result in significant noise levels in an operator cab, which may be not only distracting, but also dangerous. It is well known that exposure to high decibel noise over extended periods of time can permanently damage an individual's hearing.
To reduce noise levels, exhaust systems typically include attenuation devices, such as mufflers. Currently, each machine type has its own unique exhaust system or muffler design, since machines typically have different operating conditions, engine speeds, sound testing points, engine back pressure restrictions, and other limitations. For example, current mufflers are typically tuned to a single frequency or a narrow range of frequencies, depending on the application. A typical muffler installed in a work machine, for instance, may utilize resonator chambers to help attenuate noise in the high frequency band. Enlarging resonator chambers, however, results in a larger muffler overall and may elevate a surface temperature of the muffler.
Utilizing an incorrect muffler design can directly affect engine performance. If the muffler design causes an increase in back pressure, and the resulting back pressure is too high, the “breathing ability” and subsequent performance of the engine could be negatively impacted. Generally, increased back pressure results in lower fuel efficiency, decreased performance, and even a limited altitude range for a given engine, among other disadvantages.
Prior attempts to improve muffler sound attenuation have been directed to various geometric arrangements for directing flow of exhaust gas through various chambers within the muffler housing. For example, U.S. Pat. No. 4,359,135 discloses a muffler that utilizes an input tube and an output tube, with solid partitions to create a number of chambers within the muffler housing. One partition, between a flow chamber and a large resonator chamber, includes two apertures, which permit a limited amount of exhaust gas to travel from the input tube to the large resonator chamber. The system also utilizes a conversion-divergent nozzle, which is installed in the exhaust output tube to reflect a portion of the sound waves attempting to enter the output tube back into the flow chamber.
Designing and producing a different muffler system for each machine application can be both expensive and time consuming. Sometimes, mufflers are not tuned well or their noise reduction capability drops with changes in operating conditions and temperatures. There is consequently a need for a compact, cost-efficient sound attenuation device that performs consistently at both low and high frequencies, over a broad range of operating conditions, and manages sound reduction and back pressure requirements for a broad range of machines.
In accordance with one aspect of the present disclosure, an engine system is disclosed. The engine system may comprise an engine having at least one cylinder, each one having a combustion chamber, a piston, and an exhaust valve configured to release exhaust gases. The engine system may also include an exhaust system in fluid communication with the engine, including an exhaust pipe, as well as an exhaust muffler. The muffler may have a housing including an exterior wall, a concentric interior wall, a first end cap and a second end cap opposite the first end cap. Proximate the first end cap may be a first perforated end plate, and proximate the second end cap may be a second perforated end plate. Positioned between the first perforated end plate and the second perforated end plate may be a plurality of perforated baffles. The muffler may also include an inlet pipe in fluid communication with the exhaust pipe, and an outlet pipe. The inlet pipe may be disposed within the interior wall and extend through the first end cap, through the first end plate, and through the plurality of perforated baffles. A portion of the inlet pipe may be perforated. The outlet pipe may be disposed within the interior wall and extend through the second end cap, through the second end plate, and through the plurality of perforated baffles. A portion of the outlet pipe may also be perforated.
In accordance with another aspect of the present disclosure, an exhaust muffler for use with an internal combustion engine is disclosed. The exhaust muffler may comprise a housing including an exterior wall, a concentric interior wall, a first end cap and a second end cap opposite the first end cap. Disposed within the housing may be a plurality of partitions that may define a plurality of chambers. The muffler may also include an inlet pipe disposed within the interior wall and extending through the first end cap, through the plurality of partitions, and through the second end cap. A portion of the inlet pipe may be perforated. The muffler may further include an outlet pipe disposed within the interior wall and extending through the second end cap, through the plurality of partitions, and through the first end cap. A portion of the outlet pipe may be perforated.
In accordance with yet another aspect of the present disclosure, an exhaust muffler for an internal combustion engine is disclosed. The exhaust muffler may include a housing with an exterior wall, a concentric interior wall, a first end cap and a second end cap opposite the first end cap. Disposed within the housing may be a plurality of partitions, defining a plurality of chambers. The chambers may include a first resonator chamber proximate the first end cap, a second resonator chamber proximate the second end cap, and a cross-flow chamber positioned between the first resonator chamber and the second resonator chamber. An inlet pipe may be disposed within the interior wall and extend through the first end cap, through the first resonator chamber, through the cross-flow chamber and into the second resonator chamber. A portion of the inlet pipe within the cross-flow chamber may be perforated. An outlet pipe may be disposed within the interior wall and extend through the second end cap, through the second resonator chamber, through the cross-flow chamber and into the first resonator chamber. A portion of the outlet pipe within the cross-flow chamber may be perforated.
These and other aspects and features of the present disclosure will be better understood upon reading the following detailed description, when taken in conjunction with the accompanying drawings.
Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts.
The present muffler 20 may be generally cylindrical, flat oval, oval or rectangular in shape and includes a housing 22, which may be constructed from sound damping materials, ferrous or other metallic materials, or anti-corrosion materials. Example materials may include ferrous alloys, aluminum, aluminized steel, titanium alloys, and ceramics. Ferrous materials may be particularly resistant to the heat expelled by the engine system. Anti-corrosion materials may prevent rust or other corrosion, which may be caused by any combination of water, salt, or other environmental conditions placed on the engine system and muffler 20. Further, the housing 22 may be coated in a heat-resistant material, such as a heat-resistant paint.
A mounting base plate 24 may be fixed to an exterior surface 26 of the housing 22, for example, by welding, with adhesives, or by any other means that preserve the structural integrity of the housing. Fixed to the mounting base plate 24 is a mounting bracket 28 having a plurality of apertures 30. The mounting bracket 28 may be fixed to the mounting base plate 24, for example, by welding, with adhesives, or by any other means that preserve the structural integrity of the housing 22. The mounting bracket 28 may be dimensioned to allow for installation of a bracket 32, or other mechanism that supports or stabilizes a machine part installed in the engine system near the muffler 20. Supporting and stabilizing the machine part may not only reduce vibration of the machine part, but may also protect the muffler 20 from damage caused by excess vibrations or erratic movement of the machine (not shown). The exemplary arrangement in
Referring now to
Referring to
The end plates 50, 52 and the baffle plates 54 may be dimensioned to fit within an interior wall 62, which may be disposed within the housing 22. Insulation material 64 may be installed or packed between the interior wall 62 and the exterior wall 42, to provide thermal insulation and additional sound attenuation within the muffler 20. Insulation material 64 may also be installed or packed between the first end plate 50 and the first end cap 44, as well as between the second end plate 52 and the second end cap 46. The insulation material 64 may be formed from one or a combination of sound and heat absorbing materials, such as fiberglass, or other fibrous material. The interior wall 62 may contain perforated regions 66, or its entire surface may be perforated, to encourage sound attenuation and heat absorption. Typical small or compact mufflers require use of a heat shield disposed within or around the body of the muffler, since they typically include little-to-no insulating material. The present muffler 20, however, utilizes a layer of insulation material 64 that is thick enough to negate the need for a heat shield or other heat barrier. The thickness of the insulation material 64 may be approximately 2 inches. Other thicknesses, however, are also contemplated.
The muffler 20 may also include an inlet pipe 68, disposed within the housing 22, and configured for fluid communication with the exhaust pipe 13 of the exhaust system, such that exhaust gases and sound waves are directed through the muffler. More specifically, the inlet pipe 68 includes an inlet 70, through which the exhaust gases and sound waves enter the muffler 20. The inlet pipe 68 may be positioned within the interior wall 62, and may extend through the first end cap 44, through each of the plurality of partitions 50, 52, 54 and chambers 56, 58, 60, and through the second end cap 46. More specifically, an end 74 of the inlet pipe 68 opposite the inlet 70 may extend beyond the exterior surface 26 of the housing 22. An inlet plug member 72 may be inserted in the end 74 of the inlet pipe 68 to seal the end of the inlet pipe, and to prevent flow of the exhaust gas from the inlet pipe to the atmosphere. The inlet plug member 72 may be positioned such that it is radially aligned with the layer of insulation material 64 installed between the second end plate 52 and the second end cap 46.
With specific reference to
The muffler 20 of the present disclosure may further include an outlet pipe 82 (
The outlet pipe 82 may include the outlet 84, through which the exhaust gases and sound waves exit the muffler 20. The outlet pipe 82 may extend through the second end cap 46, through each of the plurality of partitions 50, 52, 54 and chambers 56, 58, 60, and through the first end cap 44. More specifically, the end 86 of the outlet pipe 82 opposite the outlet 84 may extend beyond the exterior surface 26 of the housing 22. An outlet plug member 88 may be inserted in the end 86 of the outlet pipe 82 to seal the outlet pipe, and to prevent flow of the exhaust gas from the end 86 of the outlet pipe to the atmosphere. The plug member 88 may be positioned such that it is radially aligned with the layer of insulation material 64 installed between the first end plate 50 and the first end cap 44.
With specific reference to
Another embodiment of the present muffler 20 is shown in
As shown in
As illustrated in
The muffler 20 of the present disclosure may further include an outlet pipe 110 (
The outlet pipe 110 may include the outlet 112, through which the exhaust gases and sound waves exit the muffler 20. The outlet pipe 110 may be positioned within the interior wall 62, and may extend through the second end cap 46, through the second end plate 52, and through each of the plurality of baffle plates 122, into the first resonator chamber 94. The open end 114 of the outlet pipe 110 opposite the outlet 112 may extend into the first resonator chamber 94. As illustrated in
In practice, the teachings of the present disclosure may find applicability in many industries including, but not limited to, construction and earth moving equipment. For example, the present disclosure may be beneficial to medium wheel loaders, motor graders, track-types tractors, and other machines with diesel engine systems. The present disclosure provides an exhaust muffler with interchangeable inlet and outlet pipes, insulation material for thermal insulation and high frequency attenuation, reduced back pressure, and overall noise attenuation in both low frequency and mid-high frequency broadband flow noise, which is enhanced compared to previous mufflers designed for these applications throughout the industry.
Internal combustion engines provide power to various machines, such as, but not limited to, earth moving equipment, on-highway trucks or vehicles, off-highway trucks or machines, locomotives, generators, pumps, and other mobile and stationary applications. During operation, an internal combustion engine produces sound waves from the repeated opening of exhaust valves and the expulsion of exhaust gases as the sound waves propagate through the exhaust gas flow. The muffler 20 of the present disclosure is configured to reduce noise at both high and low frequencies and fulfill back pressure requirements from different machine applications with similar engine applications. It has been designed such that it will perform consistently over a broad frequency range, and, for example, handle various engine frequency firing orders. The present muffler 20 is also compatible with machines that have no aftertreatment system, as well as those that have an aftertreatment system. For example, the muffler 20 of the present disclosure may be installed onto a preexisting exhaust system to add additional sound attenuation, if necessary. This situation may be most applicable if the machine is located in a country that regulates exhaust noise levels (e.g. the United States, Australia, European countries) in order to comply with changing regulations.
In accordance with a first embodiment of the present disclosure, the inlet pipe 68 of the muffler 20 may be coupled to the exhaust pipe 13 of an internal combustion engine (not shown). The flow of exhaust gas may be directed through the inlet pipe 68. When the flow of exhaust gas impacts the inlet plug member 72, the exhaust gas and sound waves are dispersed through the perforated portion 76 of the inlet pipe into the second chamber 58. Some sound waves may be absorbed by the insulation material 64 through the perforated regions 66 of the interior wall 62 and the perforated second end plate 52, while other sound waves may be reflected and cancelled, thereby allowing for sound attenuation.
The exhaust gas flow continues from the second chamber 58 through the perforated baffle plates 54 and middle chamber 60 and into the first chamber 56. Sound waves continuing to propagate within the exhaust gas flow may be absorbed by the insulation material 64 through the perforated regions 66 of the interior wall 62 and through the perforated first end plate 50, or may be scattered and undergo further reflection and cancelling in the first chamber 56 or the middle chamber 60. Finally, the exhaust gas flow may enter the outlet pipe 82 through the perforations 92 in the perforated region 90. The exhaust gas and sound waves, now trapped within the solid connective portion 93 of the outlet pipe 82, exits the muffler 20 to the atmosphere via the exhaust output pipe 14. In this embodiment, the perforated region 76 of the inlet pipe 68 may be positioned at an end of the muffler that is opposite the perforated region 90 of the outlet pipe 82. This arrangement creates a long, tortious path for the exhaust gas and sound waves, which enables dissipation of the sound waves, thereby maximizing sound attenuation.
In accordance with another embodiment of the present disclosure, the inlet pipe 100 of the muffler 20 is coupled to the exhaust pipe 13 of an internal combustion engine (not shown). The flow of exhaust gas is directed through the inlet pipe 100. As the flow of exhaust gas reaches the open end 104 of inlet pipe 100, a majority of the exhaust gas and sound waves are dispersed through the perforated region 106 of the inlet pipe into the cross-flow chamber 98, and directly into the outlet pipe 110 via the perforations 118 in the perforated region 116 of the outlet pipe. The sound waves continue into the second resonator 96, where some sound waves are absorbed by the insulation material 64 through the perforated regions 66 of the interior wall 62 and the perforated second end plate 52, and other sound waves are reflected and cancelled thereby allowing for sound attenuation. Exhaust gas and any remaining sound waves that enter the outlet pipe 110 through the perforations 118 in the perforated region 116 of the outlet pipe is forced toward the outlet 112, and exits the muffler 20 to the atmosphere via the exhaust output pipe 14. In this embodiment, the perforated region 106 of the inlet pipe 100 may be positioned within the same chamber 98 as the perforated region 116 of the outlet pipe 110, but the open end 104 of the inlet pipe 100 may be in fluid communication with the second resonator 96, and the open end 114 of the outlet pipe 110 may be in fluid communication with the first resonator 94. With the first resonator 94 being larger in volume than the second resonator 96, and with both resonators being positioned proximate each other, sound attenuation of resonant low frequencies is achieved.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and assemblies without departing from the scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
