WHISTLE REDUCTION FEATURE

RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 62/049,040, filed September 11, 2014.

BACKGROUND OF THE INVENTION

[0002] The present invention generally relates to tuning tube and exhaust tube assembly.

[0003] Vehicle exhaust systems include silencers to reduce noise that is generated by a vehicle's powertrain. In one example configuration, a silencer includes an outer housing having an exhaust inlet and an exhaust outlet. An exhaust gas flow pipe extends through the outer housing from the inlet to the outlet. A side branch tuning tube, such as a Helmholtz tube for example, is connected to the exhaust gas flow pipe within the outer housing to further facilitate reducing noise.

[0004] One disadvantage with this configuration is that a whistling noise can be generated at the connection interface between the exhaust gas flow pipe and the side branch tuning tube. Further improvements are needed to reduce or eliminate this whistling noise.

SUMMARY OF THE INVENTION

[0005] According to one exemplary embodiment, a vehicle exhaust system component includes an exhaust tube defining an exhaust gas flow path, a side branch tuning tube connected to the exhaust tube at an interface, and a porous structure associated with the exhaust tube to reduce noise generated at the interface.

[0006] In a further embodiment of the above, the porous structure comprises a portion of the exhaust tube, and wherein the side branch tuning tube has an inlet end that is fixed to the portion of the exhaust tube.

[0007] In a further embodiment of any of the above, the exhaust tube includes a perforated orifice that comprises the porous structure, and wherein the side branch tuning tube has an open inlet end that at least partially overlaps the perforated orifice. [0008] In a further embodiment of any of the above, the porous structure comprises a portion of the exhaust tube that is formed from microperforated material and wherein the side branch tuning tube has an inlet end that is fixed to the portion of the exhaust tube that is formed from microperforated material.

[0009] In a further embodiment of any of the above, the side branch tuning tube has an inlet end and an outlet end, and wherein the exhaust tube includes an opening at the interface that is associated with the inlet end of the side branch tuning tube, and wherein the porous structure comprises a sleeve that covers the opening.

[0010] In a further embodiment of any of the above, the porous structure comprises a microperforated structure, perforated structure, wire mesh structure, or woven metal structure.

[0011] In a further embodiment of any of the above, the porous structure has a predefined overall area and wherein approximately at least 40% of the predefined overall area is an open area.

[0012] In a further embodiment of any of the above, an outer housing that surrounds the exhaust tube and side branch tuning tube.

[0013] In another exemplary embodiment, a vehicle exhaust system component includes an outer housing defining an open internal cavity, wherein the outer housing includes at least one exhaust gas inlet and at least one exhaust gas outlet, and an exhaust tube positioned within the open internal cavity to define an exhaust gas flow path through the outer housing. The exhaust tube includes an inlet end coupled to the exhaust gas inlet and an outlet end coupled to the exhaust gas outlet, and wherein the exhaust tube includes a perforated orifice at a location between the inlet and outlet ends. A tuning tube is fixed to the exhaust tube, wherein the tuning tube includes a tuning tube inlet that overlaps the perforated orifice and a tuning tube outlet that is open to the internal cavity.

[0014] In a further embodiment of any of the above, the tuning tube outlet is non- concentric with the exhaust tube.

[0015] In a further embodiment of any of the above, the perforated orifice comprises a plurality of discrete holes extending through a wall thickness of the exhaust tube, and wherein the plurality of discrete holes are only located at an interface between the exhaust tube and the turning tube. [0016] These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 shows a schematic representation of a vehicle exhaust system.

[0018] Figure 2A is a perspective view of one example embodiment of a silencer.

[0019] Figure 2B is an end view of the silencer of Figure 2A.

[0020] Figure 3 is a side view of an exhaust tube and tuning tube assembly as enclosed within the silencer of Figures 2A-2B.

[0021] Figure 4 is a top view of a silencer, exhaust tube and tuning tube assembly incorporating one example embodiment of the subject invention.

[0022] Figure 5 is a side view showing the exhaust tube and tuning tube positioned within the silencer.

[0023] Figure 6A is a perspective view of one example of a mesh sleeve.

[0024] Figure 6B is an end view of the mesh sleeve positioned within the exhaust tube.

[0025] Figure 7 is a top view of another example of a silencer, exhaust tube and tuning tube assembly incorporating one example embodiment of the subject invention.

[0026] Figure 8 is a perspective view of a wire mesh screen.

[0027] Figure 9 is a top view of another example of a silencer, exhaust tube and tuning tube assembly incorporating one example embodiment of the subject invention.

[0028] Figure 10 is a top view of a mesh patch.

[0029] Figure 11 is a schematic view of an internally mounted mesh patch.

[0030] Figure 12 is a schematic view of an externally mounted mesh patch.

[0031] Figure 13 is a top view of another example of a silencer, exhaust tube and tuning tube assembly incorporating one example embodiment of the subject invention.

[0032] Figure 14 is a schematic view of an interface between the tuning tube and exhaust tube of Figure 13.

[0033] Figure 15 is a top view of another example of a silencer, exhaust tube and tuning tube assembly incorporating one example embodiment of the subject invention.

[0034] Figure 16A is a side view of the exhaust tube of Figure 15. [0035] Figure 16B is an enlarged view of a portion of the exhaust tube as identified in Figure 16 A.

DETAILED DESCRIPTION

[0036] A vehicle exhaust system 2 conducts hot exhaust gases generated by an internal combustion engine 4 through various downstream exhaust components 6 to reduce emissions and control noise as known. The exhaust components can include diesel oxidation catalysts (DOC), selective catalytic reduction (SCR) catalysts, particulate filters, mufflers, resonators, exhaust pipes, etc. These components can be mounted in various different configurations and combinations dependent upon vehicle application and available packaging space. Exhaust gases pass through the components and are subsequently directed to the external atmosphere via a tailpipe 8, for example.

[0037] Figures 2A-2B and 3-5 show one example of a vehicle muffler or silencer 10 for a vehicle exhaust system that includes an outer housing 12 that defines an open internal volume 14. The outer housing 12 includes at least one exhaust gas inlet 16 and at least one exhaust gas outlet 18. An exhaust tube 20 defines an exhaust gas flow path F through the silencer 10 from the exhaust gas inlet 16 to the exhaust gas outlet 18. The exhaust tube 20 has an inlet end 22 associated with the exhaust gas inlet 16 and an outlet end 24 associated with the exhaust gas outlet 18. In one example, the inlet end 22 is coupled to the exhaust gas inlet 16 and an outlet end 24 is coupled to the exhaust gas outlet 18 such that the exhaust tube 20 forms the sole exhaust gas flow path through the silencer 10.

[0038] A side branch tuning tube 30 is attached to the exhaust tube 20 at a location between the inlet 22 and outlet 24 ends. The side branch tuning tube 30 is connected to the exhaust tube 20 at an interface 32. In one example, the side branch tuning tube 30 comprises a Helmholtz tube. The side branch tuning tube 30 has an inlet end 34 and an outlet end 36 that is non-concentric with the exhaust tube 20. The inlet end 34 is fixed to the exhaust tube 20 and the outlet end 36 is unsupported and spaced apart from the exhaust tube 20. Thus, the exhaust tube 20 carries the exhaust flow through the silencer 10 and the side branch tuning tube 30 is a non-flow pipe that opens into the empty internal volume 14 at the outlet end 36 to facilitate noise reduction. [0039] A porous structure 40 is associated with the exhaust tube 20 to reduce noise generated at the interface 32. The porous structure 40 can be comprised of various different features or configurations and can be formed from different types of material. For example, the porous structure can comprise microperforated material, standard perforated material, wire mesh material, or woven metal material. Other porous materials that could be utilized include eglass, steel wool, and basalt for example. The porous structure can be formed as part of the exhaust tube 20 itself, or can be formed as a separate structure that is attached to the exhaust tube 20.

[0040] In one example, the porous structure 40 has a predefined overall area wherein approximately at least 40% of the predefined overall area is an open area. Test results have shown that 40% open area is a minimum area in which the low frequency Helmholtz tuning will not degrade significantly (less than 2 dB). In one example, the porous structure that defines the 40% open are includes openings that are at least 5 mm in size, for example.

[0041] In the example shown in Figures 4-6, the porous structure 40 comprises a sleeve 42 that is made from a wire mesh or woven metal material, for example. In the example, the exhaust tube 20 includes an opening 44 that is associated with the inlet end 34 of the side branch tuning tube 30. The opening 44 that is associated with the inlet end 34 of the side branch tuning tube 30 is determined by the size of the tube 30.

[0042] The sleeve 42 is positioned to cover the opening 44. The sleeve 42 can be positioned internally (Figure 6B) within the exhaust tube 20 to cover the opening 44, or the sleeve 42 could surround an outer surface of the exhaust tube 20 (Fig ures 4-5) to cover the opening 44. The sleeve 42 can be fixed in place by any of various attachment methods such as welding or brazing, for example.

[0043] The side branch tuning tube 30 is attached to the exhaust tube 20 at the interface 32, which is at the opening 44. The side branch tuning tube 30 can be attached using any of various attachment methods including welding or brazing for example.

[0044] In another example, the porous structure 40 comprises a patch 50 (Figures 9-12) that covers the opening 44. The patch 50 can be internally (Figure 9) or externally (Figure 12) mounted to cover the opening 44. The patch (Figure 10) can be formed as a wire mesh or steel wool patch, for example. [0045] In another example, the porous structure 40 is positioned within the exhaust tube 20 immediately upstream or downstream of the opening 44 (Figure 7). For example, the porous structure 40 could be a sleeve 42 or patch 50 that is mounted internally within the exhaust tube 20 at an upstream or downstream location relative to the opening 44.

[0046] In the examples discussed above, the sleeve 42 or patch 50 is comprised of a single layer of porous material. However, the sleeve or patch could also be formed from multiple layers of material such as a steel wool or fiber layer in combination with an expanded metal (microperforated material), wire mesh, or perforated sheet of material.

[0047] In another example, the porous structure 40 comprises a portion 60 of the exhaust tube 20 that is formed as microperforated material (Figures 13-14). This type of material has a high density of very small openings extending through the tube wall. This material is discussed in greater detail in applicant's application number PCT/US2014/032302 filed on March 31, 2014, and which is herein incorporated by reference.

[0048] The inlet end 34 of the side branch tuning tube 30 is fixed to the portion 60 of the exhaust tube 20 that is formed from microperforated material. This configuration has the advantage that a separate piece of material is not required to be attached to the exhaust tube 20. Further, while the portion 60 could be formed as microperforated material, the portion 60 could include standard pipe perforations dependent upon the level of noise control desired.

[0049] Such an example is shown in Figures 15 and 16A-16B. As discussed above, the outer housing 12 defines an open internal cavity 14 and includes at least one exhaust gas inlet 16 and at least one exhaust gas outlet 18. The exhaust tube 20 is positioned within the open internal cavity 14 to define an exhaust gas flow path through the outer housing 12. The inlet end 22 of the exhaust tube 20 is coupled to the exhaust gas inlet 16 and an outlet end 24 is coupled to the exhaust gas outlet 18. In this example, the exhaust tube 20 includes a perforated orifice 70 at a location between the inlet 22 and outlet 24 ends. The tuning tube 30 is fixed to the exhaust tube 20 such that a tuning tube inlet 72 overlaps the perforated orifice 70 and a tuning tube outlet 74 is open to the internal cavity 14.

[0050] In one example, the perforated orifice 70 comprises a plurality of discrete holes 76 extending through a wall thickness of the exhaust tube 20. The plurality of discrete holes 76 are only located at an interface between the exhaust tube 20 and the turning tube 30. [0051] The subject invention uses a porous structure or feature at a large orifice interface wherein the porous structure is comprised of a plurality of openings each having at least a 5 mm diameter at the overlap between an exhaust pipe and a tuning pipe. By using a perforated orifice, or by using a porous structure upstream or downstream of the interface 32 or opening, or by using a mesh sleeve or patch to cover the opening, the fluid boundary layer is disturbed such that organized vertical structures cannot form across the interface/opening. As such, standing waves are not produced, which therefore reduces or eliminates whistling noise at this location.

[0052] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.

[0053] Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.