Dual-mode silencer

Abstract

A silencer assembly for a vehicle exhaust system, comprising a silencer with a primary silencer pipe containing a primary resonator, a secondary silencer pipe with a secondary resonator, and a valve that directs the exhaust flow, depending on the valve's position, through both the primary and secondary silencer pipes or primarily through the secondary silencer pipe. The silencer provides a first level of sound attenuation when the valve is in an open position and a second level of sound attenuation when the valve is in a closed position. The second level of sound attenuation is higher than the first, and therefore the silencer produces a louder exhaust sound when the valve is open and a quieter exhaust sound when the valve is closed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 534,472, filed August 24, 2023. The entire disclosure of the above-referenced application is incorporated herein by reference. AREA

[0002] The present disclosure relates to vehicle exhaust systems and, more particularly, to exhaust system mufflers and methods of manufacturing exhaust system mufflers. BACKGROUND

[0003] The background description provided herein is intended to provide a general context for the disclosure. The work of the above-referenced inventors, to the extent described in this background section, as well as aspects of the description that might not otherwise be prior art at the time of filing, are neither expressly nor by implication admitted to be prior art over the present disclosure.

[0004] Vehicles equipped with an internal combustion engine typically direct the exhaust gas flow produced by the engine through a series of pipes commonly referred to as the vehicle's exhaust system. The exhaust flow through the exhaust system generally increases with increasing engine speed, changing the volume and tone of the noise produced by the exhaust flow as it passes through the exhaust system. Many vehicle exhaust systems use active valves to change the noise level and / or sound characteristics (e.g., pitch) produced by the exhaust system during vehicle operation. Many vehicle manufacturers and exhaust system manufacturers refer to such systems as "sports exhausts" because they are a popular option among motorsport enthusiasts who desire a louder or "sportier" exhaust note. Active valves (e.g.,Electromechanical valves (EVOs) can be installed to direct exhaust flow into different ducts and / or chambers of the exhaust system, making the exhaust noise louder or quieter at the driver's discretion. These active valves are typically controlled by a button or other user interface inside the vehicle. SUMMARY

[0005] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0006] According to one aspect of the present disclosure, a muffler assembly for a vehicle exhaust system is provided, including a muffler having a primary muffler conduit with a primary resonator, a secondary muffler conduit with a secondary resonator, and a valve that directs exhaust flow through both the primary and secondary muffler conduits or only the secondary muffler conduit, depending on the position of the valve. The primary resonator has a primary resonator chamber, and the secondary resonator has a secondary resonator chamber. The primary muffler conduit passes through the primary resonator chamber to define a primary exhaust flow path through the muffler. The secondary muffler conduit extends through at least a portion of the secondary resonator chamber to define a secondary exhaust flow path within the muffler.

[0007] The valve is positioned upstream of the primary resonator and is operable between an open and a closed position. Thus, exhaust flow is permitted through both the primary muffler conduit and primary exhaust flow path and the secondary muffler conduit and secondary exhaust flow path when the valve is in the open position, providing a first mode of operation. The muffler thus provides a first level of sound attenuation in the first mode of operation. In the closed position, the valve restricts exhaust flow through the primary muffler conduit and primary exhaust flow path such that more than 50 percent of the exhaust flow is directed through the secondary muffler conduit and secondary exhaust flow path when the valve is in the closed position, providing a second mode of operation.The muffler thus provides a second level of sound attenuation in the second operating mode. The second level of sound attenuation is greater than the first level of sound attenuation. As a result, the muffler provides a louder exhaust noise (i.e., higher decibels) in the first operating mode and a quieter exhaust noise (i.e., lower decibels) in the second operating mode.

[0008] According to this aspect of the disclosure, the primary resonator has a primary resonator cross-sectional area (A1), and the primary muffler conduit has a primary muffler conduit cross-sectional area (a1) that is smaller than the primary resonator cross-sectional area (A1). The secondary resonator has a secondary resonator cross-sectional area (A2), and the secondary muffler conduit has a secondary muffler conduit cross-sectional area (a2) that is smaller than the secondary resonator cross-sectional area (A2). The sizes of the primary and secondary resonators and the primary and secondary muffler conduit are selected such that a primary area ratio (A1 / a1) of the primary resonator cross-sectional area (A1) divided by the primary muffler conduit cross-sectional area (a1) is smaller than a secondary area ratio (A2 / a2) of the secondary resonator cross-sectional area (A2) divided by the secondary muffler conduit cross-sectional area (a2).This particular design specification allows the muffler's second (quieter) operating mode to reduce the noise level generated by the vehicle's exhaust system at any engine speed (rpm) without significantly affecting the exhaust note (i.e., frequency, pitch, resonance, burble, etc.). Therefore, the acoustic characteristics of the exhaust note remain the same in the first and second operating modes; the exhaust sound is simply quieter (i.e., exhibits lower decibel levels) in the second operating mode.

[0009] According to another aspect of the present disclosure, a muffler assembly for a vehicle exhaust system is provided, including a muffler including a primary muffler conduit having a primary resonator, a secondary muffler conduit having a secondary resonator, and a valve that directs exhaust flow through both the primary and secondary muffler conduits or primarily through the secondary muffler conduit, depending on the position of the valve. The primary muffler conduit, the primary resonator, the secondary muffler conduit, and the secondary resonator are positioned within a muffler housing. In particular, the primary muffler conduit passes through the primary resonator and the muffler housing to define a primary exhaust flow path through the muffler.The secondary muffler duct extends within the muffler body to define a secondary exhaust flow path within the muffler.

[0010] Again, the valve is positioned upstream of the primary resonator and is operable between an open and a closed position. Thus, exhaust flow is permitted through both the primary muffler line and primary exhaust flow path and the secondary muffler line and secondary exhaust flow path when the valve is in the open position, providing a first mode of operation. The muffler thus provides a first level of sound attenuation in the first mode of operation. In the closed position, the valve restricts exhaust flow through the primary muffler line and primary exhaust flow path such that more than 50 percent of the exhaust flow is directed through the secondary muffler line and secondary exhaust flow path when the valve is in the closed position, providing a second mode of operation.The muffler thus provides a second level of sound attenuation in the second operating mode. The second level of sound attenuation is greater than the first level of sound attenuation. As a result, the muffler provides a louder exhaust noise (i.e., higher decibels) in the first operating mode and a quieter exhaust noise (i.e., lower decibels) in the second operating mode.

[0011] According to this aspect of the disclosure, the primary resonator is formed by a first crush can positioned within the muffler housing and over the primary muffler conduit, forming a primary resonator chamber between the primary muffler conduit and the first crush can. The secondary resonator includes a secondary resonator chamber formed between the first crush can and the muffler housing. The secondary muffler conduit is fluidly connected to the first muffler conduit at a second crush can positioned within the muffler housing. The second crush can abuts the first crush can and is positioned over the primary muffler conduit, forming a diffusion chamber between the primary muffler conduit and the second crush can.The primary muffler line includes circumferentially spaced openings that allow the exhaust flow passing through the secondary muffler line and the diffusion chamber in the second squeeze can to enter the primary muffler line with reduced turbulence and flow noise.

[0012] According to another aspect of the disclosure, a method for assembling the muffler assemblies described above is provided. The method includes the steps of assembling a primary resonator by positioning a first compression can over a primary muffler conduit, connecting the secondary muffler conduit to a primary inlet port in an inlet head of a muffler housing, and connecting a secondary muffler conduit to a secondary inlet port in the inlet head of the muffler housing. The method further includes the steps of installing the primary muffler conduit and the secondary muffler conduit within an outer shell of the muffler housing to form a secondary resonator within the muffler housing, and connecting the primary muffler conduit to a single outlet port in an outlet head of the muffler housing.

[0013] The method further includes the steps of positioning a second crush can over the primary muffler conduit to form a diffusion chamber between the primary muffler conduit and the second crush can, positioning the second crush can in abutting arrangement with the first crush can, and securing the second crush can to the first crush can. According to these steps, the diffusion chamber is disposed in fluid communication with the primary muffler conduit through circumferentially spaced openings in the primary muffler conduit. The method further comprises the step of connecting the secondary muffler conduit in fluid communication with a crush can inlet on the second crush can to form a junction between the primary and secondary muffler conduits within the muffler housing.

[0014] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are provided for illustrative purposes only and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present disclosure will be better understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a plan view of an exemplary vehicle exhaust system equipped with muffler assemblies constructed in accordance with the present disclosure; Fig. 2 a cross-sectional view from above of the Fig. 1 illustrated exemplary muffler arrangements; Fig. 3 a partial view of the Fig. 2 illustrated silencer arrangement in cross-section from above; Fig. 4 another cross-sectional view from above of the Fig. 2, in which several welds can be seen in the muffler assembly; Fig. 4A is a top cross-sectional view of an alternative muffler assembly incorporating a connector; Fig. 4B is a top cross-sectional view of another alternative muffler assembly; Fig. 5 is a flowchart illustrating an exemplary method for assembling the Fig. 2 illustrates the exemplary silencer arrangement shown; Fig. 6 is another flowchart illustrating another exemplary method for assembling the Fig. 2 illustrated exemplary muffler arrangement; Fig. 7 is a top cross-sectional view of another exemplary muffler assembly having an active valve shown in an open position such that exhaust flow through the muffler assembly passes through a primary muffler conduit and a secondary muffler conduit, providing a first operating mode with a louder exhaust noise; Fig. 7A is a top cross-sectional view of another exemplary muffler assembly including a connector; Fig. 7B is a top cross-sectional view of another alternative muffler assembly; and Fig. 8 a cross-sectional view from above of the Fig. 7, in which the active valve is shown in a closed position such that exhaust flow through the muffler assembly passes through the secondary muffler conduit and provides a second mode of operation with a quieter exhaust noise.

[0016] Reference numerals may be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0017] Referring to the figures, wherein like reference numerals designate corresponding parts throughout the several views, muffler assemblies 100, 200 for a vehicle exhaust system 10 are disclosed.

[0018] Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0019] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" can also include the plural forms, unless the context clearly indicates otherwise. The terms "comprise," "comprising," "including," and "having" are inclusive and therefore specify the presence of stated features, integers, steps, acts, elements, and / or components, but exclude the presence or addition of one or more other features, integers, steps, acts, elements, components, and / or groups thereof.The procedure steps, processes, and operations described herein should not be construed as necessarily being performed in the order discussed or illustrated, unless expressly identified as such. It is also understood that additional or alternative steps may be used.

[0020] When an element or layer is described as being "on," "engaging," "connected," or "coupled to" another element or layer, it may be directly on, engaged, connected, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, an element described as being "directly on," "directly engaging," "directly connected," or "directly coupled to" another element or layer may have no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted similarly (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items.

[0021] Although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as "first," "second," and other numerical terms, when used herein, do not imply a sequence or order unless clearly indicated by the context.Thus, a first element, component, region, layer, or portion discussed below could be referred to as a second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.

[0022] Spatially relative terms such as "inner," "outer," "beneath," "under," "lower," "above," "upper," and the like may be used herein for ease of description to describe the relationship of one element or feature to one or more other elements or features, as illustrated in the figures. Spatially relative terms may be intended to encompass various orientations of the device in use or operation, in addition to the orientation illustrated in the figures. For example, if the device in the figures is turned over, elements described as being "below" or "below" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an above and below orientation.The device may be oriented differently (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein are interpreted accordingly.

[0023] With reference to Fig. 1 illustrates an exemplary vehicle exhaust system 10. The vehicle exhaust system 10 shown is a motor vehicle exhaust system configured to direct exhaust gases generated by an internal combustion engine from one or more exhaust inlets 12 located at the front of the vehicle exhaust system 10 to one or more exhaust outlets 14 located at the rear of the vehicle exhaust system 10. In Fig. 1, the vehicle exhaust system 10 includes a first exhaust line 16 positioned closer to the right side of the vehicle and a second exhaust line 18 positioned closer to the left side of the vehicle. In Fig. 1, each exhaust line 16, 18 has an inlet 12 and an outlet 14, one or more exhaust pipe sections 20 and a resonator 22. The Fig. The vehicle exhaust system 10 shown in Figure 1 also includes a mixing section 24, such as an X-pipe, that fluidly connects the first and second exhaust tracts 16, 18. It should be noted that the inlets 12 are configured to be connected to the outlets of catalysts, exhaust headers, downpipes, or other components of the exhaust system, and thus receive the exhaust gases and heat generated by the internal combustion engine. The outlets 14 are open to the atmosphere and therefore release the exhaust gases and heat to the environment. Each of the inlets 12 Fig. The exhaust tract 16, 18 shown in Figure 1 includes a resonator 22 located upstream of the mixing section 24 (i.e., located between the inlet 12 and the mixing section 24) and a muffler assembly 100 located downstream of the mixing section 24 (i.e., located between the mixing section 24 and the outlet 14). The muffler assemblies 100 are specifically designed to provide, at any given engine speed (rpm), a first operating mode with a louder exhaust sound and a second operating mode with a quieter exhaust sound, without changing the acoustic characteristics of the exhaust sound (i.e., frequency, pitch, resonance, burble, etc.) other than the noise level (dB).

[0024] The Fig. The vehicle exhaust system 10 shown in Figure 1 is particularly designed for use in motor vehicles equipped with a six-cylinder in-line engine with two turbochargers, one turbocharger receiving the exhaust gases from three of the six cylinders and the other turbocharger receiving the exhaust gases from the other three cylinders. Thus, the downpipe from one of the turbochargers carries the exhaust gases from three cylinders to the inlet 12 of the first exhaust line 16, and the downpipe from the other turbocharger carries the exhaust gases from the other three cylinders to the inlet 12 of the second exhaust line 18. A particular problem faced by the inventors in developing the muffler assemblies 100, 200 described below was to produce a muffler assembly that allows for both a loud and a quiet operating mode without changing the character of the exhaust note when switching between the two different operating modes.A second problem faced by the inventors was the manufacture of such a muffler arrangement that supplies a single outlet 14 per exhaust line 16, 18.

[0025] Although the development of the silencer assemblies 100, 200 described herein is consistent with the Fig. 1 and the associated problems described above, it should be noted that Fig. 1 shows only one exemplary configuration for a vehicle exhaust system 10 and that many other exhaust system configurations are possible, including, without limitation, exhaust system configurations that do not have the Fig. 1 illustrated resonators 22 and / or mixing sections 24, exhaust systems in which each exhaust line 16, 18 has several outlets 14, and exhaust systems which have only one exhaust line instead of the two in Fig. 1. Therefore, the muffler assemblies 100, 200 shown and described herein can be used in a wide variety of vehicle exhaust systems and are not limited in their application to the exhaust systems shown in Fig. 1 shown exemplary vehicle exhaust system 10.

[0026] Still referring to Fig. 1, each muffler assembly 100 includes a muffler 101. The muffler 101 includes a muffler housing 102 having an outer shell 104 having a substantially oval cross-sectional shape and closed at the inlet and outlet ends by an inlet header 106 and an outlet header 108. Each muffler assembly 100 also includes a primary inlet pipe 103 and a secondary inlet pipe 105 connected to the inlet header 106 of the muffler 101, and a single outlet pipe 107 connected to the outlet header 108. The primary and secondary inlet pipes 103, 105 are joined at a joint 109 that places the primary and secondary inlet pipes 103, 105 in fluid communication with the exhaust pipe section 20 in each of the first and second exhaust tracts 16, 18. The primary inlet pipe 103 has a larger diameter than the secondary inlet pipe 105.An active electromechanical valve 111 is positioned in the primary inlet pipe 103 and is operable between an open position in which exhaust gas flow through the primary inlet pipe 103 is permitted, and a closed position in which the active electromechanical valve 111 blocks and thus restricts exhaust gas flow through the primary inlet pipe 103. As will be explained in more detail below, the open position of the active electromechanical valve 111 provides a first mode of operation in which exhaust gas flows into the muffler assembly 100 through both the primary and secondary inlet pipes 103, 105 and in which the sound attenuation provided by the muffler assembly 100 is minimal to produce a loud exhaust noise. The closed position of the active electromechanical valve 111 provides a second mode of operation in which all or a majority of the exhaust gas flow (i.e.more than 50 percent) of which enters the muffler assembly 100 through the secondary inlet pipe 105, resulting in greater sound attenuation by the muffler assembly 100 and a quieter exhaust sound compared to the first operating mode, still maintaining the same exhaust note but at lower decibel (dB) levels.

[0027] With additional reference to Fig. 2, the muffler 101 includes a primary muffler conduit 113 and a secondary muffler conduit 115. The primary muffler conduit 113 extends linearly through the muffler housing 102 from the inlet header 106 to the outlet header 108 (i.e., the primary muffler conduit 113 is a straight tube or conduit). The primary muffler conduit 113 has a primary conduit wall 117 having a tubular shape and including a first set of perforations 118. The primary conduit wall 117 extends linearly between an upstream primary conduit end 119 and a downstream primary conduit end 121. The inlet head 106 includes a primary inlet opening 123 that receives the upstream primary conduit end 119 with a close tolerance fit, and the outlet head 108 includes a single outlet opening 125 that receives the downstream primary conduit end 121 with a close tolerance fit.A downstream end of the primary inlet tube 103 is received within the primary inlet opening 123 and the upstream primary conduit end 119 in a close tolerance fit to form an overlapping joint. An upstream end of the single outlet tube 107 is received within the single outlet tube opening 125 and the downstream primary conduit end 121 in a close tolerance fit to form an overlapping joint. Thus, the primary muffler conduit 113 is disposed in fluid communication with and transports exhaust gas between the primary inlet tube 103 and the single outlet tube 107, thus defining a primary exhaust flow path 127 through the muffler 101.

[0028] The secondary muffler conduit 115 includes a secondary conduit wall 129 having a tubular shape and including a second set of perforations 131. The secondary conduit wall 129 is curved and extends between an upstream secondary conduit end 133 and a downstream secondary conduit end 135. The inlet header 106 includes a secondary inlet opening 137 that receives the upstream secondary conduit end 133 in a close tolerance fit. A downstream end of the secondary inlet tube 105 is received within the secondary inlet opening 137 and the upstream secondary conduit end 133 in a close tolerance fit to form an overlapping joint. Thus, the secondary muffler conduit 115 defines a secondary exhaust flow path 138 through the muffler 101.

[0029] The muffler 101 also includes a primary resonator 139 and a secondary resonator 141 positioned within the muffler housing 102. The primary resonator 139 is formed by a first crush can 143 positioned within the muffler housing 102. More specifically, the first crush can 143 is positioned over the primary muffler conduit 113. The first crush can 143 has a first crush can wall 145 that has a tubular shape and extends linearly between an upstream end of the first crush can 147 and a downstream end of the first crush can 149. Thus, a primary resonator chamber 151 is formed by the space between the primary conduit wall 117 and the first crush can wall 145. The secondary resonator 141 includes a secondary resonator chamber 153 formed by the space between the first crush can 143 and the muffler housing 102.The first set of perforations 118 in the primary conduit wall 117 is arranged in fluid communication with the primary resonator chamber 151 and is configured to allow sound to propagate from the primary muffler conduit 113 into the primary resonator chamber 151. The second set of perforations 131 in the secondary conduit wall 129 is arranged in fluid communication with the secondary resonator chamber 153 and is configured to allow sound to propagate from the secondary muffler conduit 115 into the secondary resonator chamber 153. The primary resonator chamber 151 and / or the secondary resonator chamber 153 may, but are not required to, contain a sound-damping material 155. For example, and without limitation, the sound-damping material 155 may be fiberglass roving configured to absorb and attenuate sound in specific frequency ranges.It should therefore be noted that the primary and secondary resonator chambers 151, 153 in the muffler 101 serve only to attenuate sound and do not themselves define exhaust flow paths within the muffler 101. In other words, the primary and secondary resonator chambers 151, 153 function as enclosed volumes within the muffler 101 and are not equipped with an inlet and outlet for the exhaust flow. Optionally, one or more baffles 157 can be positioned within the secondary resonator chamber 153 to tune resonant frequency ranges within the secondary resonator chamber 153.

[0030] The primary resonator 139 has a primary resonator cross-sectional area A1 defined by the first compression can 143, and the primary muffler conduit 113 has a primary muffler conduit cross-sectional area a1 that is smaller than the primary resonator cross-sectional area A1. The secondary resonator 141 has a secondary muffler cross-sectional area A2 defined by the outer shell 104 of the muffler housing 102, and the secondary muffler conduit 115 has a secondary muffler conduit cross-sectional area a2 that is smaller than the secondary resonator cross-sectional area A2.It should be noted that the primary resonator cross-sectional area A1 and the primary muffler conduit cross-sectional area a1 are substantially perpendicular to the exhaust gas flow through / along the primary exhaust flow path(s) 127, and that the secondary resonator cross-sectional area A2 and the secondary muffler conduit cross-sectional area a2 are substantially perpendicular to the exhaust gas flow through / along the secondary exhaust flow path(s) 138. The primary and secondary resonators 139, 141 and the primary and secondary muffler conduits 113, 115 are sized such that a primary area ratio A1 / a1 of the primary resonator cross-sectional area A1 divided by the primary muffler conduit cross-sectional area a1 is smaller than a secondary area ratio A2 / a2 of the secondary resonator cross-sectional area A2 divided by the secondary muffler conduit cross-sectional area a2.For example, the primary resonator 139 (defined by the first crush can 143) and the primary muffler conduit 113 are sized such that the primary area ratio A1 / a1 of the primary resonator cross-sectional area A1 divided by the primary muffler conduit cross-sectional area a1 can be greater than 1 and less than 4. The secondary resonator 141 (defined by the outer shell 104 of the muffler housing 102) and the secondary muffler conduit 115 are sized such that the secondary area ratio A2 / a2 of the secondary resonator cross-sectional area A2 divided by the secondary muffler conduit cross-sectional area a2 can be greater than 4 and less than 100. This particular geometry allows the second (quieter) operating mode of the muffler 101 to reduce the noise level generated by the vehicle exhaust system 10 at any engine speed (rpm) without having a significant impact on the exhaust note (i.e.the frequency, pitch, resonance, gurgling, etc.). Therefore, the acoustic characteristics of the exhaust sound remain the same in the first and second operating modes; the exhaust noise is just quieter (i.e., has lower decibel values) in the second operating mode.

[0031] With additional reference to Fig. 3, the secondary muffler conduit 115 is fluidly connected to the primary muffler conduit 113 via a second crush can 159 positioned within the muffler housing 102. The second crush can 159 includes a second crush can wall 161 extending between an upstream end of the second crush can 163 and a downstream end of the second crush can 165. The second crush can 159 is positioned over the primary muffler conduit 113, and the upstream end of the second crush can 163 abuts the downstream end of the first crush can 149 in a close tolerance, overlapping sliding fit, forming a diffusion chamber 167 between the primary conduit wall 117 and the second crush can wall 161.The second crimp wall 161 includes a crimp inlet 169 that receives the downstream secondary conduit end 135 in a close tolerance fit to form an overlapping joint.

[0032] The primary muffler conduit 113 includes circumferentially spaced openings 171 in the primary conduit wall 117 that allow the exhaust flow passing through the secondary muffler conduit 115 and the diffusion chamber 167 in the second crush can 159 to enter the primary muffler conduit 113 with reduced turbulence and flow noise. The circumferentially spaced openings 171 in the primary conduit wall 117 are positioned along a limited arc length, leaving an imperforate region 173 in the primary conduit wall 117 that is aligned with the crush can inlet 169 of the second crush can 159.As the exhaust flow exits the downstream secondary conduit end 135 and enters the diffusion chamber 167 in the second pinch can 159, the imperforate region 173 of the primary conduit wall 117 prevents the exhaust flow from directly entering the primary muffler conduit 113 and forces the exhaust flow in the diffusion chamber 167 to spread around a perimeter of the primary conduit wall 117 before entering the primary muffler conduit 113. As a result, the exhaust gas in the diffusion chamber 167 of the second pinch can 159 flows radially inward through the circumferentially spaced openings 171 in the primary conduit wall 117 as the exhaust gases enter the primary muffler conduit 113. This arrangement further reduces turbulence and flow noise.

[0033] As in Fig. 4A, an alternative muffler 101a is shown. Muffler 101a is substantially similar to muffler 101. Accordingly, similar elements are designated by like reference numerals including the suffix "a." The primary, and possibly only, difference between muffler 101a and muffler 101 is a connector 110a that acts as a conduit connecting primary resonator chamber 151a to secondary resonator 153a. It is contemplated that muffler 101a could include a plurality of connectors 110a extending through crush can wall 145a at spaced-apart locations. Alternatively, connector 110a could simply be defined as an opening extending through first crush can 143a without the presence of an additional cylindrical tube.

[0034] Another alternative silencer 101b is in Fig. 4B. Muffler 101b is substantially similar to muffler 101. Therefore, similar elements are identified by like reference numerals including the suffix "b." A primary difference between muffler 101b and muffler 101 is the provision of a secondary outlet opening 126b at the secondary conduit end 135b of the secondary muffler conduit 115b. Note that the secondary conduit wall 129b no longer faces toward the second crush can 159a. The secondary muffler conduit 115a does not encounter the crush can inlet 169 ( Fig. 4) and is not in fluid communication with it. On the contrary, the secondary silencer line 115b may have the shape of a straight, circular hollow cylinder extending along a straight line, as in Fig. 4B.

[0035] The opening previously referred to as the single exhaust port 125 with respect to muffler 101 is now referred to as the primary exhaust port 125b. In this arrangement, the exhaust flow path 127b is not connected to the exhaust flow path 138b downstream of the attenuation volume.

[0036] With further reference to the Fig. 1 to 4, the first and second compression cans 143, 159 may be attached to the primary muffler line 113 in various ways. For example, and without limitation, the first and second compression cans 143, 159 may be attached to the Fig. 4. According to this example, the upstream end of the first crimp can 147 may be welded to the primary conduit wall 117 at the weld joint 175a. Similarly, the downstream end of the first crimp can 149 may be welded to the primary conduit wall 117 at the weld joint 175b. The upstream end of the second crimp can 163 is designed to slide over the downstream end of the first crimp can 149 in a close tolerance overlapping sliding fit and is secured to the first crimp can wall 145 by a weld joint 175c.The upstream end of the second crimp can 163 may be spot welded to the downstream end of the first crimp can 149 to form one or more local welds 175c spaced circumferentially around the first crimp can wall 145, since the overlapping fit between the upstream end of the second crimp can 163 and the downstream end of the first crimp can 149 provides a seal (i.e., the weld(s) 175c may not provide a seal). Finally, the downstream end of the second crimp can 165 may be welded to the primary conduit wall 117 at weld 175d. Although many different welding techniques may be employed, the welds 175a, 175b, and 175c may be formed, for example and without limitation, by pierce welding, spot welding, or roller burning.Alternatively, the welded joints 175a, 175b and 175c could be replaced by Ridge-Lock joints.

[0037] With reference to Fig. 5 illustrates a method for assembling the muffler 101 described above. The method includes step 1A of assembling the primary resonator 139 by positioning the first crimp can 143 over the primary muffler conduit 113 and step 2A of securing the upstream and downstream ends of the first crimp cans 147, 149 to the primary conduit wall 117 by forming welds 175a and 175b.The method then continues with step 3A of positioning / sliding the second crush can 159 over the primary muffler conduit 113 until the upstream end of the second crush can 163 receives the downstream end of the first crush can 149 in a sliding fit and abutment arrangement to form the diffusion chamber 167 between the primary muffler conduit 113 and the second crush can 159, which is disposed in fluid communication with the primary muffler conduit 113 through the circumferentially spaced openings 171 in the primary conduit wall 117.

[0038] Thus, according to the Fig. 5, step 3A of positioning the second crimp can 159 over the primary muffler line 113 until the upstream end of the second crimp can 163 abuts the downstream end of the first crimp can 149 is performed after steps 1A and 2A of assembling the primary resonator 139 by positioning the first crimp can 143 over the primary muffler line 113 and securing the upstream and downstream ends of the first crimp cans 147, 149 to the primary line wall 117. The Fig. 5 continues with step 4A of securing the upstream end of the second crimp can 163 to the first crimp can wall 145 by making a weld 175c and securing the downstream end of the second crimp can 165 to the primary conduit wall 117 by making a weld 175d.

[0039] The Fig. 5 also includes step 5A of connecting the downstream secondary conduit end 135 to the pinch can inlet 169 on the second pinch can 159 to form a junction between the primary and secondary muffler conduits 113, 115 within the muffler housing 102.The method further includes step 6A of connecting the upstream primary conduit end 119 to the primary inlet opening 123 in the inlet head 106, step 7A of connecting the upstream secondary conduit end 133 to the secondary inlet opening 137 in the inlet head 106, step 8A of installing the primary and secondary muffler conduits 113, 115 and the first and second crush cans 143, 159 within the outer shell 104 of the muffler housing 102, which form the secondary resonator 141 within the muffler housing 102, and step 9A of connecting the downstream primary conduit end 121 to the single outlet opening 125 in the outlet head 108. It should be noted that steps 5A-9A may be performed in a different order than that described above and in . Fig. 5 and that one or more of steps 5A-9A may be performed before one or more of steps 1A-4A.

[0040] With reference to Fig. 6 illustrates an alternative method for assembling the muffler 101 described above. This alternative method includes step 1B of positioning / sliding the downstream end of the first crimp can 149 into the upstream end of the second crimp can 163 in a sliding fit to form an abutment arrangement between the first and second crimp cans 143, 159, and step 2B of securing the downstream end of the first crimp can 149 to the upstream end of the second crimp can 163 by forming a spot weld 175c.The method continues with step 3B of positioning / sliding the first and second crush cans 143, 159 over the primary muffler conduit 113 to form the primary resonator 139 and the diffusion chamber 167 between the primary muffler conduit 113 and the second crush can 159 disposed in fluid communication with the primary muffler conduit 113 through the circumferentially spaced openings 171 in the primary conduit wall 117.

[0041] Thus, according to the Fig. 6, step 1B of positioning / sliding the downstream end of the first crimp can 149 into the upstream end of the second crimp can 163 in a sliding fit to form an abutment arrangement between the first and second crimp cans 143, 159, and step 2B of securing the downstream end of the first crimp can 149 to the upstream end of the second crimp can 163 prior to step 3B of positioning / sliding the first and second crimp cans 143, 159 over the primary muffler conduit 113 to form the primary resonator 139 and the diffusion chamber 167. Fig. 6 then continues with step 4B of securing the upstream and downstream ends of the first crimp can 147, 149 and the downstream end of the second crimp can 165 to the primary conduit wall 117 by making welds 175a, 175b and 175d.

[0042] The Fig. 6 also includes step 5B of connecting the downstream secondary conduit end 135 to the pinch can inlet 169 on the second pinch can 159 to form a junction between the primary and secondary muffler conduits 113, 115 within the muffler housing 102.The method further includes step 6B of connecting the upstream primary conduit end 119 to the primary inlet opening 123 in the inlet head 106, step 7B of connecting the upstream secondary conduit end 133 to the secondary inlet opening 137 in the inlet head 106, step 8B of installing the primary and secondary muffler conduits 113, 115 and the first and second crush cans 143, 159 within the outer shell 104 of the muffler housing 102, which form the secondary resonator 141 within the muffler housing 102, and step 9B of connecting the downstream primary conduit end 121 to the single outlet opening 125 in the outlet head 108. It should be noted that steps 5B-9B are performed in a different order than that described above and in . Fig. 6 and that one or more of steps 5B-9B may be performed before one or more of steps 1B-4B.

[0043] With reference to the Fig. 7 and Fig. 8 is another silencer arrangement 200 for the Fig. 1 illustrates the vehicle exhaust system 10. The Fig. 7 and Fig. The silencer assembly 200 shown in Figure 8 has many of the same components as those shown in Fig. 1 to 4, but in the Fig. 7 and Fig. 8, the primary resonator 239 and the secondary resonator 241 of the silencer 201 are separate components separated by a small gap. Rather than repeating the description presented above, the following paragraphs describe the structure and function of the components in the Fig. 7 and Fig. 8, which are new and / or different from those used in connection with the Fig. 1 to 4. It should be noted that the reference numerals in the Fig. 1 to 4 are numbers of the “100s” series (e.g. 100, 102, 104 etc.), while the components in the Fig. 7 and Fig. 8, which are compatible with the components of the Fig. 1 to 4 are identical or similar to the silencer assembly 100 shown, have the same basic reference numerals, but are listed as numbers of the “200” series (e.g., 200, 202, 204, etc.). Therefore, for element 200 in the Fig. 7 and Fig. 8 the same description as for element 100 and so on and so forth.

[0044] The muffler assembly 200 includes a muffler 201 including a primary resonator 239 with a primary resonator chamber 251 and a secondary resonator 241 with a secondary resonator chamber 253. A primary muffler conduit 213 passes through the primary resonator chamber 251 to define a primary exhaust flow path 227 through the muffler 201. A secondary muffler conduit 215 passes through the secondary resonator chamber 253 to define a secondary exhaust flow path 238 through the muffler 201. The primary resonator 239 includes a primary resonator housing 202a, and the secondary resonator 241 includes a secondary resonator housing 202b separate and spaced from the primary resonator housing 202a.Each of the primary and secondary resonator housings 202a, 202b has an outer shell 204a, 204b having a substantially circular cross-sectional shape and closed at the inlet and outlet ends by a primary or secondary inlet head 206a, 206b and a primary or secondary outlet head 208a, 208b, respectively.

[0045] The muffler assembly 200 also includes a primary inlet tube 203 connected to the primary inlet head 206a, a secondary inlet tube 205 connected to the secondary inlet head 206b, a primary outlet tube 207a connected to the primary outlet head 208a, and a secondary outlet tube 207b connected to the secondary outlet head 208b. The primary inlet tube 203 has a larger diameter than the secondary inlet tube 205, and the primary outlet tube 207a has a larger diameter than the secondary outlet tube 207b. The primary and secondary inlet tubes 203, 205 are connected at a first junction 209a located outside and upstream of the muffler 201, thereby fluidly connecting the primary and secondary inlet tubes 203, 205.The primary and secondary outlet pipes 207a, 207b are connected at a second connection point 209b located outside and downstream of the muffler 201, whereby the primary and secondary outlet pipes 207a, 207b are in fluid communication with each other.

[0046] An active electromechanical valve 211 is positioned in the primary inlet pipe 203 and is switchable between an open position (as in Fig. 7) in which the exhaust gas flow is allowed through the primary inlet pipe 203, and a closed position (as shown in Fig. 8), in which the active electromechanical valve 211 blocks and thus restricts the exhaust gas flow through the primary inlet pipe 203. As shown in Fig. 7, the open position of the active electromechanical valve 211 provides a first operating mode in which the exhaust flow into the muffler 201 flows through both the primary inlet pipe and the secondary inlet pipe 203, 205, and in which the sound attenuation provided by the muffler 201 is minimal to produce a loud exhaust noise. As shown in Fig. 8, the closed position of the active electromechanical valve 211 provides a second operating mode in which all or a majority (i.e., more than 50 percent) of the exhaust flow into the muffler 201 is through the secondary inlet pipe 205, resulting in greater sound attenuation by the muffler 201 and a quieter exhaust sound compared to the first operating mode, still maintaining the same exhaust note but at lower decibel (dB) levels.

[0047] Further with reference to the Fig. 7 and Fig. 8, the primary muffler conduit 213 extends linearly through the primary resonator housing 202a from the primary inlet header 206a to the primary outlet header 208a (i.e., the primary muffler conduit 213 is a straight tube or conduit). The primary muffler conduit 213 includes a primary conduit wall 217 having a tubular shape and including a first set of perforations 218. The primary conduit wall 217 extends linearly between an upstream primary conduit end 219 and a downstream primary conduit end 221. The primary inlet header 206a includes a primary inlet opening 223 that receives the upstream primary conduit end 219 in a close tolerance fit, and the primary inlet header 208a includes a primary outlet opening 225a that receives the downstream primary conduit end 221 in a close tolerance fit.A downstream end of the primary inlet tube 203 is received within the primary inlet opening 223 and the upstream primary conduit end 219 in a close tolerance fit to form an overlapping joint. An upstream end of the primary outlet tube 207a is received within the primary outlet opening 225a and the downstream primary conduit end 221 in a close tolerance fit to form an overlapping joint. Thus, the primary muffler conduit 213 is disposed in fluid communication with the primary inlet tube 203 and the primary outlet tube 207a and transports exhaust gas between them to define the primary exhaust flow path 227 through the muffler 201.

[0048] The secondary muffler conduit 215 includes a secondary conduit wall 229 having a tubular shape and including a second set of perforations 231. The secondary conduit wall 229 extends linearly between an upstream secondary conduit end 233 and a downstream secondary conduit end 235 (i.e., the secondary muffler conduit 215 is a straight tube or conduit). The secondary inlet header 206b includes a secondary inlet opening 237 that receives the upstream secondary conduit end 233 in a close tolerance fit. A downstream end of the secondary inlet tube 205 is received within the secondary inlet opening 237 and the upstream secondary conduit end 233 in a close tolerance fit to form an overlapping joint. The secondary outlet head 208b includes a secondary outlet opening 225b that receives the downstream secondary conduit end 235 in a close tolerance fit.An upstream end of the secondary outlet pipe 207b is received within the secondary outlet opening 225b and the downstream secondary conduit end 235 in a close tolerance fit to form an overlapping joint. Thus, the secondary muffler conduit 215 is disposed in fluid communication with the secondary inlet pipe 205 and the secondary outlet pipe 207b and transports exhaust gases between them to define the secondary exhaust flow path 238 through the muffler 201.

[0049] The first set of perforations 218 in the primary conduit wall 217 is arranged in fluid communication with the primary resonator chamber 251 and is configured to allow sound to propagate from the primary silencer conduit 213 into the primary resonator chamber 251. The second set of perforations 231 in the secondary conduit wall 229 is arranged in fluid communication with the secondary resonator chamber 253 and is configured to allow sound to propagate from the secondary silencer conduit 215 into the secondary resonator chamber 253. The primary resonator chamber 251 and / or the secondary resonator chamber 253 may contain a sound-damping material 255, such as fiberglass roving.

[0050] The primary resonator 239 has a primary resonator cross-sectional area A1 as defined by the outer shell 204a of the primary resonator housing 202a, and the primary muffler conduit 213 has a primary muffler conduit cross-sectional area a1 that is smaller than the primary resonator cross-sectional area A1. The secondary resonator 241 has a secondary resonator cross-sectional area A2 as defined by the outer shell 204b of the secondary resonator housing 202b, and the secondary muffler conduit 215 has a secondary muffler conduit cross-sectional area a2 that is smaller than the secondary resonator cross-sectional area A2.It should be noted that the primary resonator cross-sectional area A1 and the primary muffler conduit cross-sectional area a1 are substantially perpendicular to the exhaust gas flow through / along the primary exhaust flow path(s) 227 and that the secondary resonator cross-sectional area A2 and the secondary muffler conduit cross-sectional area a2 are substantially perpendicular to the exhaust gas flow through / along the secondary exhaust flow path(s) 238.

[0051] The primary and secondary resonators 239, 241 and the primary and secondary muffler lines 213, 215 are dimensioned such that a primary area ratio A1 / a1 of the primary resonator cross-sectional area A1 divided by the primary muffler line cross-sectional area a1 is smaller than a secondary area ratio A2 / a2 of the secondary resonator cross-sectional area A2 divided by the secondary muffler line cross-sectional area a2. For example, the primary resonator 239 and the primary muffler line 213 are dimensioned such that the primary area ratio A1 / a1 of the primary resonator cross-sectional area A1 divided by the primary muffler line cross-sectional area a1 can be greater than 1 and less than 4.The secondary resonator 241 and the secondary muffler conduit 215 are sized such that the secondary area ratio A2 / a2 of the secondary resonator cross-sectional area A2 divided by the secondary muffler conduit cross-sectional area a2 can be greater than 4 and less than 100. This particular geometry allows the second (quieter) operating mode of the muffler 201 to reduce the noise level generated by the vehicle exhaust system 10 at any engine speed (rpm) without significantly affecting the exhaust note (i.e., frequency, pitch, resonance, burble, etc.). Therefore, the acoustic characteristics of the exhaust note remain the same in the first and second operating modes; the exhaust sound is simply quieter (i.e., has lower decibel levels) in the second operating mode.

[0052] Another alternative is in Fig. 7A and designated by reference numeral 201'. Muffler 201' is substantially similar to muffler 201. Accordingly, similar elements are designated by like reference numerals suffixed with a prime. Muffler 201' differs from muffler 201 primarily in the provision of a connector 210' that allows fluid communication between primary resonator chamber 251' and secondary resonator chamber 253'. Connector 210' is contemplated as a hollow tube extending through outer shell 204a' and outer shell 204b'. Optionally, additional connectors 210' may also be provided to fluidly connect primary resonator chamber 251' to secondary resonator chamber 253'.

[0053] Fig. 7B shows another alternative muffler with the reference numeral 201". Muffler 201'' is substantially similar to muffler 201, so that similar elements are identified by like reference numerals containing a double-bar suffix. The main difference between muffler 201 and muffler 201'' is the removal of the first connection point 209b, as shown in Fig. 7. In the alternative muffler 201'', the secondary outlet tube 207b'' does not bend toward the primary outlet tube 207a'', but runs straight and remains spaced from the primary outlet tube 207a''. A distal end 212a'' of the primary outlet tube 207a'' defines a primary outlet tube opening 214a''. A distal end 212b'' of the secondary outlet tube 207b'' defines a secondary outlet tube opening 214b''. Similar to the Fig.In the muffler 101b shown in Figure 4B, the exhaust flow path 227'' and the exhaust flow path 238'' remain separate from each other without any physical connection between the exhaust flow paths downstream of the attenuation volumes.

[0054] Many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while remaining within the scope of the appended claims. These foregoing statements should be construed to cover all combinations in which inventive novelty will be utilized. With respect to the methods set forth herein, the order of the steps may vary from the order in which they appear without departing from the scope of the present disclosure and the appended method claims. Moreover, various steps of the method may be performed sequentially or concurrently. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 534,472

[0001]

Claims

[1] Silencer assembly for a vehicle exhaust system, comprising: a silencer including a primary resonator having a primary resonator chamber and a secondary resonator having a secondary resonator chamber; a primary muffler conduit passing through the primary resonator chamber to define a primary exhaust flow path through the muffler; a secondary muffler conduit extending through at least a portion of the secondary resonator chamber to define a secondary exhaust flow path within the muffler; and a valve positioned upstream of the primary resonator, which can be actuated between an open and a closed position, wherein exhaust gas flow is permitted through both the primary muffler conduit and the primary exhaust flow path and the secondary muffler conduit and the secondary exhaust flow path when the valve is in the open position to produce a first level of sound attenuation provided by the muffler in a first operating mode, wherein the valve restricts exhaust flow through the primary muffler conduit and the primary exhaust flow path in the closed position such that more than 50 percent of the exhaust flow is directed through the secondary muffler conduit and the secondary exhaust flow path when the valve is in the closed position to produce a second level of sound attenuation provided by the muffler in a second operating mode that is greater than the first level of sound attenuation provided by the muffler in the first operating mode, wherein the primary resonator has a primary resonator cross-sectional area (A1) and the primary silencer line has a primary silencer line cross-sectional area (a1) which is smaller than the primary resonator cross-sectional area (A1), wherein the secondary resonator has a secondary resonator cross-sectional area (A2) and the secondary silencer line has a secondary silencer line cross-sectional area (a2) which is smaller than the secondary resonator cross-sectional area (A2), wherein the primary and secondary resonators and the primary and secondary silencer lines are dimensioned such that a primary area ratio (A1 / a1) of the primary resonator cross-sectional area (A1) divided by the primary silencer line cross-sectional area (a1) is smaller than a secondary area ratio (A2 / a2) of the secondary resonator cross-sectional area (A2) divided by the secondary silencer line cross-sectional area (a2). [2] The muffler assembly of claim 1, further comprising: a primary inlet pipe arranged in fluid communication with the primary muffler conduit; and a secondary inlet pipe disposed in fluid communication with the secondary muffler conduit and connected to the primary inlet pipe at a first connection point located external to the muffler. [3] The muffler assembly of claim 2, wherein the primary resonator includes a primary resonator housing and the secondary resonator includes a secondary resonator housing separate and spaced from the primary resonator housing. [4] The muffler assembly of claim 3, further comprising: a primary outlet pipe arranged in fluid communication with the primary muffler line; and a secondary outlet pipe arranged in fluid communication with the secondary muffler line and connected to the primary outlet pipe at a second connection point located external to the muffler. [5] The muffler assembly of claim 4, wherein the primary muffler conduit includes a primary conduit wall that is perforated, has a tubular shape, and extends linearly through the primary resonator housing from the primary inlet tube to the primary outlet tube, and wherein the secondary muffler conduit includes a secondary conduit wall that is perforated, has a tubular shape, and extends linearly through the secondary resonator housing from the secondary inlet tube to the secondary outlet tube. [6] The muffler assembly of claim 3, further comprising: a primary outlet pipe disposed in fluid communication with the primary muffler conduit and including a primary outlet pipe opening; and a secondary outlet pipe disposed in fluid communication with the secondary muffler conduit and including a secondary outlet pipe opening spaced from the primary outlet pipe opening. [7] The muffler assembly of claim 6, further comprising: a single outlet pipe arranged in fluid communication with the primary muffler line. [8] A muffler assembly according to claim 4, wherein the primary muffler conduit comprises a primary conduit wall that is perforated, has a tubular shape, and extends linearly through the primary resonator housing from the primary inlet pipe to the single outlet pipe, the primary resonator being formed by a crush can positioned within the muffler housing and over the primary conduit wall such that the primary resonator chamber is formed between the primary conduit wall and the crush can, the secondary muffler conduit comprising a secondary conduit wall that is perforated, has a tubular shape, and extends within the muffler housing from the secondary inlet pipe to a second junction located within the muffler housing where the secondary muffler conduit joins the primary muffler conduit,and wherein the secondary resonator chamber is formed between the crush can and the silencer housing., [9] The muffler assembly of claim 1, wherein the muffler includes a connector that places the primary resonator chamber in fluid communication with the secondary resonator chamber. [10] A muffler assembly according to claim 3, wherein the valve is an active electromechanical valve including an electronic actuator connected to the movable valve element and driving its movement between the open and closed positions. [11] The muffler assembly of claim 1, wherein the primary and secondary muffler conduits are perforated tubes and wherein at least one of the primary resonator chamber and the secondary resonator chamber contains sound-damping material. [12] The muffler assembly of claim 1, wherein the primary resonator cross-sectional area (A1) and the primary muffler conduit cross-sectional area (a1) are substantially perpendicular to the exhaust gas flow through the primary exhaust gas flow path, and wherein the secondary resonator cross-sectional area (A2) and the secondary muffler conduit cross-sectional area (a2) are substantially perpendicular to the exhaust gas flow through the secondary exhaust gas flow path.

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