Patent Application
20200392880
The present disclosure relates to a vehicle exhaust system. More particularly, the present disclosure relates to damping of sound generated by the vehicle exhaust system.
A vehicle exhaust system directs exhaust gas generated by an internal combustion engine to external environment. The exhaust system may include various components, such as pipes, converters, catalysts, filters, and the like. During operation of the exhaust system, as a result of resonating frequencies, the components may generate undesirable noise. Different methods have been employed in various applications to address this issue.
For example, the components, such as mufflers, resonators, valves, and the like, have been incorporated into the exhaust system to attenuate certain resonance frequencies generated by the exhaust system. However, such additional components are expensive and increase weight of the exhaust system. Also, adding new components into the exhaust system introduce new sources of undesirable noise generation.
A well-known sound attenuating method is a Standing Wave Management (SWM) technology. The SWM includes an opening provided on an exhaust pipe. The opening provides a secondary exhaust leak path for sound to exit the exhaust pipe and minimizes leakage of the exhaust gas through the opening. The SWM utilizes a series of holes to allow sound waves to exit the exhaust pipe while limiting leakage of the exhaust gas. In some instances, the holes may be covered with a microperforated material to dampen the noise. In order to achieve a desired noise attenuation, the holes have to be relatively large in size.
However, the microperforated material is very thin and is not as structurally sound as a solid pipe wall of the exhaust pipe. As such, creating holes in the microperforated material may adversely affect durability of the microperforated material. Additionally, if relatively larger holes are cut into the exhaust pipe and covered with the microperforated material, durability of the exhaust pipe may also be adversely affected. Another concern is with grazing flow that may occur across a surface of the microperforated material. The acoustic properties of the microperforated material may change when the exhaust gas flows across the surface of the microperforated material. This may often reduce an ability of an acoustic wave to propagate through the micro perforations, which may limit the damping effect.
Additionally, the SWM has a well-known failure mode when debris, such as salt or mud, may plug the opening. The SWM may include multilayer parts where the debris may accumulate behind the multilayer parts and result in premature failure of the SWM. Also, for efficient functioning of the SWM, a desired diameter size of each of the series of holes may have to be less than 1 millimeter (mm). However, conventional manufacturing methods make it difficult to produce a 1 mm diameter hole in a material thicker than 1 mm. More specifically, durability of the component may be compromised if component thickness may be limited to 1 mm. Hence, there is a need for an improved vehicle exhaust system for such applications.
In an example, a U.S. Patent describes a vehicle exhaust system including an exhaust component having an outer surface and an inner surface that defines an internal exhaust component cavity. At least one hole is formed in the exhaust component to extend through a wall of the exhaust component from the outer surface to the inner surface. A member is formed from a resistive material and is configured to overlap the at least one hole. At least one spacer is configured to space the member away from the inner or outer surface of the exhaust component to create an open cavity between the member and the exhaust component. In one example, an actuator is configured to cover and uncover the member dependent upon an operating characteristic to vary damping.
In another example, a U.S. Patent describes a device for preventing shock excitation of an acoustic enclosure. The device includes a pressure anti-nodal point comprising a mechanical oscillator. The mechanical oscillator is exposed to the acoustic enclosure at the anti-nodal point. The mechanical oscillator is also tuned to resonate at a frequency for which the anti-nodal point is the pressure anti-node.
Given description covers one or more above mentioned problems and discloses a method and a system to solve the problems.
In an aspect of the present disclosure, a vehicle exhaust system is provided. The vehicle exhaust system includes a tubular component having an inner surface and an outer surface. The inner surface defines a primary exhaust gas flow path. The tubular component defines a central axis extending between an inlet end and an outlet end of the tubular component. The vehicle exhaust system also includes at least one opening defined by the tubular component. The at least one opening provides a secondary exhaust gas flow path. The at least one opening extends through each of the inner surface and the outer surface. The vehicle exhaust system further includes a patch adapted to cover the at least one opening. The patch includes a first portion extending parallel to the central axis. The first portion defines a plurality of pores. The first portion covers the at least one opening. The patch also includes a second portion extending away from the first portion. The first portion has a first thickness and the second portion has a second thickness.
In another aspect of the present disclosure, a tubular component for a vehicle exhaust system is provided. The tubular component includes an inner surface and an outer surface. The inner surface defines a primary exhaust gas flow path. The tubular component defines a central axis extending between an inlet end and an outlet end of the tubular component. The tubular component also includes at least one opening. The at least one opening provides a secondary exhaust gas flow path. The at least one opening extends through each of the inner surface and the outer surface. The tubular component further includes a patch adapted to cover the at least one opening. The patch includes a first portion extending parallel to the central axis. The first portion defines a plurality of pores. The first portion covers the at least one opening. The patch also includes a second portion extending away from the first portion. The first portion and the second portion together form an integral structure. The first portion has a first thickness and the second portion has a second thickness. The patch also includes at least one wire mesh insert. The at least one wire mesh insert is coupled with the first portion to cover at least one of the plurality of pores. The at least one wire mesh insert further includes an integrated retention system for coupling with the first portion of the patch.
In yet another aspect of the present disclosure, a patch adapted to cover at least one opening in a tubular component of a vehicle exhaust system is provided. The patch includes a plurality of pores. The patch also includes at least one wire mesh insert. The at least one wire mesh insert is coupled with the patch to cover at least one of the plurality of pores. The at least one wire mesh insert includes a first head portion, a second head portion, and an intermediate portion. The intermediate portion extends between each of the first head portion and the second head portion. Each of the first head portion and the second head portion is adapted to couple the at least one wire mesh insert with the patch. The intermediate portion is adapted to be disposed in at least one of the plurality of pores.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts. Referring to
The system 100 includes a number of downstream exhaust components 104 fluidly coupled to the engine 102. The exhaust components 104 may include a number of systems/components (not shown), such as a Diesel Oxidation Catalyst (DOC), a Diesel Exhaust Fluid (DEF) unit, a Selective Catalytic Reduction (SCR) unit, a particulate filter, an exhaust pipe, and the like. The exhaust components 104 may be mounted in various different configurations and combinations based on application requirements and/or available packaging space. The exhaust components 104 are adapted to receive the exhaust gas from the engine 102 and direct the exhaust gas to the external atmosphere via a tailpipe 106. The exhaust components 104 are adapted to reduce emissions and control noise.
The system 100 also includes an acoustic damping member, such as a muffler 108. The muffler 108 is provided in fluid communication with the exhaust components 104 and the tailpipe 106. In the illustrated embodiment, the muffler 108 is disposed downstream of the exhaust components 104 and upstream of the tailpipe 106. In other embodiments, the muffler 108 may be disposed in any sequence with respect to each of the exhaust components 104 and/or the tailpipe 106, based on application requirements. The muffler 108 is adapted to dampen resonance frequencies generated during operation of the engine 102 and the system 100.
Referring to
The tubular component 202 also includes an opening 212. In the illustrated embodiment, the tubular component 202 includes a single opening 212. In other embodiments, the tubular component 202 may include multiple openings, based on application requirements. The opening 212 extends through each of the inner surface 204 and the outer surface 206. In the illustrated embodiment, the opening 212 has a substantially rectangular configuration. In other embodiments, the opening 212 may have any other configuration, such as circular, triangular, elliptical, and the like. The opening 212 provides a secondary exhaust gas flow path in association with the primary exhaust gas flow path.
The system 100 also includes a patch 214 coupled to the tubular component 202. More specifically, the patch 214 is disposed adjacent to the opening 212 in order to cover the opening 212. Referring to
The patch 214 includes a first portion 302. The first portion 302 has a substantially flat configuration defining a first thickness “T1” (shown in
Referring to
Referring to
For example, in some embodiments, the patch 214 may include only the pores 304 (as described with reference to
Referring to
More specifically, in the illustrated embodiment, the second portion 310 includes a first rib 312, a second rib 314, a third rib 316, a fourth rib 318, and a central rib 320. Each of the first rib 312, the second rib 314, the third rib 316, the fourth rib 318, and the central rib 320 defines a frame of the patch 214. In the illustrated embodiment, each of the first rib 312, the second rib 314, the third rib 316, and the fourth rib 318 is disposed in a manner to form the rectangular configuration of the patch 214. Also, the central rib 320 is disposed between each of the first rib 312 and the third rib 316 in order to provide structural rigidity to the patch 214. In other embodiments, the second portion 310 may include any number of ribs arranged in any configuration, based on application requirements.
It should be noted that a configuration of the second portion 310 including each of the first rib 312, the second rib 314, the third rib 316, the fourth rib 318, and the central rib 320 described herein is merely exemplary and may vary based on application requirements. For example, referring to
The patch 214 further includes one or more wire mesh inserts 322. Each of the wire mesh inserts 322 is coupled with the first portion 302 in order to cover each of the pores 308. The pores 308 are similar in configuration to the configuration of the pores 306 as described with reference to
Referring to
It should be noted that the integrated retention system described herein is merely exemplary and may vary based on application requirements. For example, in other embodiments, the wire mesh insert 322 may be press fitted into one or more of the pores 304, 306, 308. In other embodiments, the wire mesh insert 322 may be snap fitted into one or more of the pores 304, 306, 308. In yet other embodiments, the wire mesh insert 322 may be integral with respect to the first portion 302 of the patch 214. Accordingly, based on a coupling method, an overall configuration of the wire mesh insert 322 may also vary.
Referring to
It should be noted that a density and/or material of the wire mesh 324 may vary based on application requirements. For example, in some situations, based on a relatively higher level of required sound damping, a high density material may be employed for the wire mesh 324. As such, due to the high density material of the wire mesh 324, escaping of the exhaust gas from the tubular component 202 through each of the pores 308 may also reduce substantially. Additionally, or alternatively, a higher number of wire mesh inserts 322 may be disposed on the first portion 302 of the patch 214 in any of the pores 304, 306, 308.
In other situations, based on a relatively lower level of required sound damping, a low density material may be employed for the wire mesh 324. Additionally, or alternatively, a lower number of wire mesh inserts 322 may be disposed on the first portion 302 of the patch 214 in any of the pores 304, 306, 308. As such, based on the number of wire mesh inserts 322 and/or material of the wire mesh 324, the patch 214 may be selectively tuned for different levels of sound damping, based on application requirements. Additionally, or alternatively, a number of patches 214 may be provided on the tubular component 202 along a length and/or diameter of the tubular component 202 in order to tune the tubular component 202 for different levels of sound damping.
It should be noted that the wire mesh insert 322 and the wire mesh 324 described herein is merely exemplary and optional. For example, in some embodiments, referring to
In yet other embodiments (not shown), the patch (not shown) may include a combination of the slots 338 and/or one or more of the pores 304, 306, 308 with or without the wire mesh inserts 322 and the wire mesh 324. Each of the slots 338 defines a thickness “T3”. The thickness “T3” may be sized in a manner to allow escaping of the sound waves while simultaneously reducing escaping of the exhaust gas through the slots 338. In some embodiments (not shown), wire mesh inserts (not shown) with wire mesh (not shown) may be disposed in one or more of the slots 338. In such a situation, the wire mesh inserts and the wire mesh may be configured in accordance with an overall configuration of the slot 338.
Referring to
Further, the patch 502 includes a thermal expansion joint 510. In the illustrated embodiment, the thermal expansion joint 510 is provided on the first portion 302. More specifically, in the illustrated embodiment, the thermal expansion joint 510 is disposed around each of the pores 506. The thermal expansion joint 510 has a substantially raised configuration relative to the first portion 302 of the patch 502. The thermal expansion joint 510 may be made of a material similar to the material of the first portion 302, such as a metal, an alloy, and the like. The thermal expansion joint 510 provides thermal expansion of the first portion 302 during operation of the system 100, in turn, limiting thermal stress and thermal failure of the patch 502.
The patch 214, 326, 336, 502, including the first portion 302 and the second portion 310, 328, may be made of any metal, alloy, or polymer, such as aluminum, tin, steel, brass, bronze, high temperature plastic, and the like. Each of the patch 214, 326, 336, 502 and the wire mesh insert 322 may be made using any manufacturing process, such as Metal Injection Molding (MIM) process. In such a situation, the patch 214, 326, 336, 502 may be manufactured as a single piece component, such that the first portion 302 and the second portion 310, 328 may together form an integral structure. Also, the wire mesh insert 322 may be manufactured as a single piece component, such that the first head portion 402, the second head portion 404, and the intermediate portion 406 may together form an integral structure.
The patch 214, 326, 336, 502 provides a simple and effective method for damping sound generated by the exhaust gas flowing through the tubular component 202. More specifically, the patch 214 includes the wire mesh inserts 322 provided in one or more of the pores 304, 306, 308. The wire mesh 324 of the wire mesh inserts 322 provides damping of sound as the sound may exit through one or more of the pores 304, 306, 308. Additionally, the wire mesh 324 limits leakage of the exhaust gas from the tubular component 202 through one or more of the pores 304, 306, 308.
The patch 214, 326, 336, 502 and/or the wire mesh insert 322 is manufactured using the MIM process. As such, one or more of the pores 304, 306, 308, 506 having the diameter “D” less than or approximately equal to 1 mm can be formed with reduced complexity on the first portion 302 having the first thickness “T1” approximately equal to or higher than 1 mm. Further, the second portion 310, 328 provides increased structural rigidity to the patch 214, 326, 336, 502. Also, the MIM process provides integral manufacturing of the first portion 302 and the second portion 310, 328, in turn, improving product durability. Additionally, the MIM process provides manufacturing the patch 214, 326, 336, 502 in three-dimensional (3D) configuration, such as with the curvature similar to the curvature of the tubular component 202.
The MIM process also provides ease of manufacturing relatively small diameter pores on a relatively higher thickness surface. The wire mesh insert 322 provides reduced accumulation of debris, such as salts, mud, dust, and the like, around one or more of the pores 304, 306, 308, in turn, reducing premature failure of the system 100. The patch 214, 326, 336, 502 with or without the wire mesh inserts 322 may be easily incorporated into existing systems with little or no modification to the existing system, in turn, providing improved product compatibility.
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 methods without departing from the spirit and 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
