Conformal transverse muffler

Embodiments in accordance with the present disclosure may provide a conformal transverse muffler including an enclosure shaped to fit around a bottom and a side of a feature of a vehicle. The enclosure may include a mid section fittable below the feature, and two side sections fittable in opposite locations only radially outside of a circumference of the spare tire well. The side sections may be thicker than the mid section and may have a vertical center above a vertical center of the mid section.

FIELD

The present application relates generally to vehicle exhaust noise attenuation, including a conformal transverse muffler shaped to fit around a bottom and a side of vehicle features, such as a spare tire well.

BACKGROUND AND SUMMARY

The repeated expulsion of exhaust gas from an engine may cause pulsed rapid movement of the gas through one or more exhaust pipes and out of one or more tail pipes. The pulsed rapid movement may create compression waves and objectionable noise, vibration and harshness (NVH). Exhaust mufflers have been used to reduce the noise. They typically serve to damp the noise, and/or to bounce the compression waves against partitions inside the muffler to create wave interference patterns to reduce the overall amplitude of the waves. Mufflers typically have an elongated oval shape, and an inlet at one longitudinal end and an outlet at the opposite end.

Tubing length and muffler volume can both help reduce noise. However, both parameters are often constrained by package limitations, especially in modern vehicles. At the same time, modern boosting techniques push more mass flow through the engine and exhaust system, potentially increasing exhaust noise.

One effort to reduce the proportion of space occupied by the vehicle muffler and exhaust tubing is disclosed in U.S. Pat. No. 4,760,894 to Harwood et al. Harwood discloses an exhaust muffler configured to accommodate a greater proportion of the available space on the vehicle. Harwood's approach recognizes a greater availability of transverse pockets of space available under the vehicle, which can require large bend tubing. To avoid large bend radius tubing, Harwood proposes a muffler with an internal configuration such that the exhaust pipe, or the tailpipe, may enter the muffler at an angle with the longitudinal axis of the muffler.

The inventors herein have recognized a number of problems with this approach. For example, the approach disclosed proposes a muffler having a substantially monolithic shape, and the resulting exhaust configuration still does not make significantly efficient use of the pockets of space under the vehicle.

Embodiments in accordance with the present disclosure may provide a conformal transverse muffler including an enclosure shaped to fit around a bottom and a side of a spare tire well of a vehicle. The enclosure may include a mid section fittable below the spare tire well, and two side sections fittable in opposite locations only radially outside of a circumference of the spare tire well. The side sections may be thicker than the mid section and may have a vertical center above a vertical center of the mid section. In this way, the available space under the vehicle may be effectively used by conforming the muffler shape to available space, thus enabling increased muffler volume within available packaging, such as for boosted engines. Further, in one example, this positioning and shaping of the muffler enables increased size of the vehicle trunk.

In one example, internal tubing may be coupled within a conformal muffler, such as described herein, and span transversely across the width to enable longer exhaust tailpipe lengths due to the wider lengths accommodated, thus meeting noise targets while also addressing backpressure issues. Such an approach is especially beneficial with dual exhaust tailpipes, since both may traverse the muffler's width in opposite directions to reduce package requirements.

Still another potential advantage is that the muffler may operate as an aerodynamic shield on the bottom of the vehicle due to its relative position under the spare tire, thus enabling improved fuel economy without requiring an additional shield, if desired.

Note that the conformal muffler may apply to single exhaust pipe systems, dual exhaust pipe systems, or systems having more exhaust pipes, as well as combinations thereof. For example, the conformal muffler may have a single exhaust inlet and a single exhaust outlet, multiple exhaust inlets and a single exhaust outlet, a single exhaust inlet and multiple exhaust outlets, duel inlets and duel outlets, or still further variations.

FIGS. 2-13are drawn approximately to scale, although other relative dimensions may be used.

DETAILED DESCRIPTION

Referring toFIG. 1, internal combustion engine10, comprising a plurality of cylinders, one cylinder of which is shown inFIG. 1, is controlled by electronic engine controller12. Engine10includes combustion chamber30and cylinder walls32with piston36positioned therein and connected to crankshaft40. Engine10may include a turbocharger in one example to boost intake air entering the engine. Combustion chamber30is shown communicating with intake manifold44and exhaust manifold48via respective intake valve52and exhaust valve54. Each intake and exhaust valve may be operated by an intake cam51and an exhaust cam53. Alternatively, one or more of the intake and exhaust valves may be operated by an electromechanically controlled valve coil and armature assembly. The position of intake cam51may be determined by intake cam sensor55. The position of exhaust cam53may be determined by exhaust cam sensor57.

Intake manifold44is also shown intermediate of intake valve52and air intake zip tube42. Fuel is delivered to fuel injector66by a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). The engine10ofFIG. 1is configured such that the fuel is injected directly into the engine cylinder, which is known to those skilled in the art as direct injection. Fuel injector66is supplied operating current from driver68which responds to controller12. In addition, intake manifold44is shown communicating with optional electronic throttle62with throttle plate64. In one example, a low pressure direct injection system may be used, where fuel pressure can be raised to approximately 20-30 bar. Alternatively, a high pressure, dual stage, fuel system may be used to generate higher fuel pressures. Additionally or alternatively fuel may be injected upstream of intake valve52via a fuel injector (not shown), which is known to those skilled in the art as port injection.

Ignition system88provides an ignition spark to combustion chamber30via spark plug92in response to controller12. Universal Exhaust Gas Oxygen (UEGO) sensor126is shown coupled to exhaust manifold48. Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor126.

Various components such as a convertor, acoustic attenuation devices (e.g., resonator, muffler), etc., may be in fluidic communication with exhaust manifold48. The convertor and acoustic attenuation devices may be included in a dual-flow exhaust system. Therefore, it will be appreciated that engine10may include a second exhaust manifold coupled to another combustion chamber. The dual-flow exhaust system is discussed in greater detail herein with regard toFIGS. 2A and 2B.

FIGS. 2A and 2Bare respective top and bottom perspective views illustrating a portion of an example dual, or dual flow, exhaust system200in accordance with the present disclosure. It will be understood that a dual-flow exhaust system200includes a first exhaust conduit, passage, or first exhaust pipe202, and a second exhaust conduit, passage, or second exhaust pipe204for directing exhaust gases away from an engine. As discussed above with regard toFIG. 1the intake system may include a throttle62, intake manifold44, etc. Thus, the intake system may be configured to provide air to the engine for combustion. It will be appreciated that additional systems may be included in example vehicles which are not depicted inFIG. 2. For example, an exhaust gas recirculation (EGR) system and/or boosting system (e.g., supercharger, turbocharger) may be provided in other embodiments.

The engine may include a number of cylinders, for example six cylinders in two cylinder banks. It will be appreciated that the engine may include an alternate number of cylinders, and/or banks, in other embodiments. The cylinders may be divided into a first cylinder bank and a second cylinder bank. Furthermore, the cylinders may be in a V type of configuration, in which the central axes of each opposing cylinder intersect at a non-straight angle. However, other cylinder configurations may be utilized in other embodiments, such as a flat or inline cylinder configuration. The engine's displacement may be for example 3.7 liters. However, other displacements may be used. The cylinders included in both of the cylinder banks may be coupled to the example dual-flow exhaust system200illustrated. The dual-flow exhaust system200may include a first exhaust pipe202coupled to a first cylinder bank. Specifically, the first exhaust pipe202may includes an input exclusively coupled to the first cylinder bank. Likewise the second exhaust pipe204may be coupled to a second cylinder bank. Specifically, the second exhaust pipe204may include an input exclusively coupled to the second cylinder bank. The dual-flow exhaust system200may further include a resonator and/or emission control sub-system206coupled to the first and second exhaust conduits. The sub-system206may include one or more devices, such as particulate filters, convertors, resonator, etc. In one example, the emission control system may include a convertor including multiple catalyst bricks. In another example, multiple emission control devices, each with multiple bricks, can be used. It will be appreciated that exhaust conduits (i.e., the first and second exhaust pipes202and204) may be fluidically separated in the emission control sub-system206. In other words, mixing of the exhaust gases from the first and second exhaust conduits may be inhibited in the emission control sub-system to maintain separated exhaust streams. It should be noted that this muffler may be used with single exhaust systems as well, and is not limited to systems with two or more exhaust pipes.

Various example embodiments may use a muffler as indicated in the figures, or one or more mufflers modified in accordance with the present disclosure that may be used with a single inlet/single outlet, single inlet/dual outlet, dual inlet/single outlet, or dual inlet/dual outlet configurations. Some example embodiments may use a single outlet configuration wherein the outlet may be placed on the left side or on the right side of the vehicle. One example may place the outlet substantially in the center of the vehicle. Some embodiments may provide various levels of flexibility by enabling an inlet, or an outlet to be plugged, and/or sealed. Internal baffling, and/or routing may be rearranged, or otherwise modified on some cases.

As discussed above combustion may be implemented via intake and exhaust valve actuation. Consequently, pulses of high pressure exhaust gases may be generated in the exhaust stream, thereby generating sound waves propagating downstream in the dual-flow exhaust system. It will be appreciated that the frequency and amplitude of the sound waves generated in the exhaust streams may depend upon the valve timing, fuel injection timing, engine speed, engine displacement, etc. It may be desirable to decrease and in some cases eliminate at least a portion of the sound waves generated in the engine and propagated through the dual-flow exhaust system to reduce noise pollution generated by the vehicle and provide the driver with a more agreeable driving experience. Therefore, muffler210may also be included in the dual-flow exhaust system200. The muffler210may be configured to attenuate a desired audible frequency or range of audible frequencies within the exhaust system200via, for example, destructive interference within an enclosure of the muffler210. In this way, noises generated via the engine may be reduced.

It will be appreciated that the exhaust system200, and the muffler210described herein may also, or instead, be used with any number of other engine types, and/or configurations. For example the muffler210, or variations thereof, could be applied to a Wankel (Rotary) engine, an Atkinson cycle engine, a Diesel cycle engine, or other internal combustion engine that may be employed in a various vehicles.

FIG. 3is a sectional view of a sample muffler210in accordance with the present disclosure shown located in an example position within a vehicle220, part of which is shown with dashed lines. Embodiments may include a conformal transverse muffler210which may include an enclosure having two side sections224and mid section222formed therebetween. The mid section may have a height less than a height of either of the side sections. In some cases the enclosure may be configured to fit around a bottom and a side of one or more vehicle features. Example vehicle features may include, but may not be limited to: one or more batteries, various storage compartments, a spare tire well, and a driveline. In one example the mid section may be fitable below a spare tire well. For example, a hybrid-electric vehicle may include an engine and exhaust system such as described herein, and may house batteries in a selected location below a vehicle trunk. As such, it may be advantageous to apply the conformal muffler approach to fit around a battery well including a plurality of batteries.

Some embodiments may include a conformal transverse muffler210which may include an enclosure212shaped to fit around a bottom214and a side216of a spare tire well218of the vehicle220. The enclosure212may include a mid section222fittable below the spare tire well218. The enclosure212may also include two side sections224fittable in opposite locations only radially outside of a circumference of the spare tire well218. The side sections224may be thicker than the mid section222and may have a vertical center226above a vertical center228of the mid section222as indicated by a first distance230shown longer than a second distance232from a common reference datum234. A tire235is shown in dashed lines in the spare tire well218. In some embodiments the side sections224may be at least partially coplanar with the spare tire well218.

The muffler210and the spare tire well218may have a space236therebetween. The space236may provide, for example thermal, or acoustical, insulation between the muffler210and the vehicle220. With some examples the enclosure includes a number of surfaces having corrugated contours237.

Referring also again toFIGS. 2A and 2Bwherein the mid section222of the muffler210may include two inlets238each respectively configured to be coupled with dual exhaust pipes202and204for exhausting gas from two respective banks of cylinders of a combustion engine. In addition, each side section224may include two outlets240each respectively configured to be coupled with tailpipes pipes242and244.

FIG. 4is a bottom view of a top portion250, or top shell, of the example muffler210in accordance with the present disclosure.FIG. 5is a top view of a bottom portion252, or bottom shell, of the muffler210.FIG. 6is a front view of the muffler210illustrating the top portion250coupled with the bottom portion252; andFIG. 7is a side view of the muffler210. The top portion250, and the bottom portion252may have a preselected depth as indicated by dimension290inFIG. 5. With at least one example embodiment this dimension may be approximately 400 mm. Other dimensions may be used. When the top portion250and the bottom portion are coupled together the muffler210may have a preselected height, at least at a first end thereof as indicated by dimension292inFIG. 6. With at least one example embodiment dimension292may be approximately 175 mm. Other dimensions may be used. In some cases the mid section222may have a preselected height, as indicated by dimension295inFIG. 6. With at least one example embodiment dimension295may be, for example, approximately 55 to 60 mm. Other dimensions may be used. A height of second end thereof may be indicated by dimension293inFIG. 7. With at least one example embodiment dimension293may be approximately 150 mm. Other dimensions may be used. A nominal distance between opposite inner sides of the side volumes224may be indicated by dimension294inFIG. 6. With at least one example embodiment dimension294may be approximately 755 mm. Other dimensions may be used. The overall width of the muffler210may be indicated with dimension296inFIG. 6. With at least one example embodiment dimension296may be approximately 1360 mm. Other dimensions may be used. An internal volume of the muffler210may be for example 40 liters, although other volumes may be used.

The relatively higher side surfaces274may define the top of the muffler210. The location of the top of the muffler210may be defined by a rear rail structure of the vehicle220. The bottom273of the muffler210may be defined by a ground clearance plane. The bottom273of the muffler210may be defined by other, or additional, considerations as well. For example, the bottom surface of the muffler may be defined by any aerodynamic shaping. As previously mentioned, the muffler210may operate as an aerodynamic shield on the bottom of the vehicle. This may enable improved fuel economy without requiring an additional shield. In this way costs may be reduced.

FIG. 8is a top view of the bottom portion of the muffler210illustrating a number of partitions254arranged to form two example expansion chambers256, an example balance passage258, and two example tailpipe extensions260. The outlet port240in each of the side sections224may be located at a downstream end of each respective tailpipe extension260. The two outlet ports240may be configured to pass exhaust to two respective tailpipes244via the two respective tailpipe extensions260. The balance passage258, or balance tube, may fluidically inter-couple the side sections224. The balance passage258may serve to equalize exhaust pulses and allow sounds waves to communicate between both banks of the engine. This may tend to produce a deeper less objectionable tone from the engine noise.

Embodiments may include two spaced apart inlets238, or inlet ports238located at a side of the mid section222and configured to receive exhaust from an internal combustion engine. wherein a first and a second of the partitions254may each include a first portion262positioned to extend from the side264of the mid section222adjacent each respective entry port238in a first direction away from the side264, and a second portion266positioned to extend in a second direction toward the side section224to direct the exhaust to each of the respective side sections224.

Various embodiments may provide a muffler210including an enclosure212. The enclosure212may include a relatively thin volume222, fittable under a one or more preselected features of a vehicle220. The one or more preselected features may be, for example, a spare tire well, or the like. The enclosure212may also include at least one relatively thick volume224fittable alongside the preselected feature, for example the spare tire well218. The enclosure212may include an exhaust gas entry port238, a tailpipe exit port240, and partitions254within the thin volume22. The partitions254may form an expansion chamber256at the entry port238, and a tail pipe extension260at the exit port240. The expansion chamber256may be formed just downstream from the entry port238.

In some embodiments at least one relatively thick volume224is two relatively thick volumes224fluidically coupled to the thin volume222on opposite sides thereof. Both relatively thick volumes224may be configured to fit alongside the spare tire well218. The entry port238may be two entry ports238. The expansion chamber256may be two expansion chambers256that may be disposed directly downstream from the respective two entry ports238. In addition to, or as an alternative to, allowing gas from the exhaust pipes202and204to expand, the expansion chamber256may also be configured to direct the stream into the respective two relatively thick volumes224. The partitions254may also form a balance tube258within the relatively thin volume222which may fluidically coupling the two relatively thick volumes224.

The enclosure212may be formed from a top shell250coupled with a bottom shell252. The bottom shell252may be tub shaped. The top shell250may include wide approximately U shaped side walls and three top surfaces270including a lower middle surface272and two relatively higher side surfaces274. With some examples the top shell250and the bottom shell252may be molded plastic shells. With some other examples the top shell250and the bottom shell252may be formed from one or more stamping operations. In one example, a single stamping may be used.

Various embodiments may provide a dual exhaust system200. The dual exhaust system200may include at least two exhaust passages202,204in fluidic communication with respective two banks of combustion chambers of an internal combustion engine. The exhaust system200may include first and second resonator chambers224in fluidic communication with the two respective exhaust passages202,204. At least two tailpipe passages260may be in fluidic communication with the first and second resonator chambers224. A balance passage258may fluidically inter-couple the first and second resonator chambers224. A portion of the each of the two exhaust passages202,204, a portion of the each of the two tailpipe passages260, and the balance passage258may all be co-located within a middle volume222included in an enclosure212. The first and second resonator chambers224may be located in the enclosure212on opposite sides of the middle volume222.

In some examples the first and second resonator chambers224may occupy relatively thick volumes and the middle volume222may occupy a relatively thin volume. The enclosure212may have a cross-sectional shape approximating a wide square U shape.

The dual exhaust system200may include, or, be coupled with, or located adjacent to a spare tire wheel well218. The enclosure212may fit around the spare tire wheel well218. The first and second resonator chambers224may be located at a height in a vehicle220approximately at a height of a spare tire235, and only radially outside of a circumference of the spare tire well218. The middle volume222may be located below the spare tire well218.

The middle volume222may include a first and a second partition254extending from respective sides of inlet holes238forming respective first and second expansion chambers256at ends of exhaust pipes202,204between a top surface280and a bottom surface282(FIG. 3) of the middle volume222and between a side wall264(FIG. 8) of the enclosure212and the first and second partitions254. A third partition254may be at a spaced apart distance from the first and second partitions254and may form the balance passage258between the top and bottom surfaces280,282of the middle volume222and the third partition254and the first and second partitions254. A fourth partition254may be located at a second spaced apart distance from the third partition254forming a first tailpipe extension260on a first side of the fourth partition254between the top and bottom surfaces280,282of the middle volume222, and a second tailpipe extension260on a second side of the fourth partition254between the top and bottom surfaces280,282of the middle volume222.

Referring now toFIGS. 9-13, and in some cases where indicated below, referring also to figures previously discussed, another example embodiment is illustrated in accordance with the present disclosure. The expansion chamber256may be formed at one or more entry ports238, and in one example may be a configured as a change in cross sectional area of the path along which the exhaust may travel. In some cases the path into the expansion chamber256may be unobstructed. In other cases the path may include one or more baffles, partitions254, or other object or the like. Baffles or walls and/or the partitions254may be integrated anywhere in the enclosure210. In this way various tuning volumes may be formed within the enclosure212.

One or more of the partitions254may have alternative preselected lengths selected in accordance with preselected criteria to tune the resonance and/or the sound produced by the muffler. Various embodiments may include adjustable partitions configurable in alternative lengths that may accordingly vary respective lengths, and/or sizes of the expansion chamber(s)256, tailpipe extension(s)260, and one or more balance passages258.

In some examples the tailpipe extensions260may be tubular members located within the enclosure. The tubular members may be integral with portions of the tailpipes242,244located external to the muffler. Various combinations may be used which may be determined based on, for example, manufacturer preferences, and/or manufacturing techniques and/or procedures. The tailpipe extension260may be two or more tailpipe extensions260that may have substantial rectangular cross sections. The muffler210may also include substantial rectangular end-forms302to mate the two or more tailpipe extensions260to respective two or more tailpipes242,244.

In some embodiments the partitions254may be positioned to form a first balance passage304located adjacent and substantially parallel (e.g., within 5%) with a forward wall306of the enclosure212, and a second balance passage308located adjacent and substantially parallel with a rearward wall310of the enclosure212(FIG. 11). In some embodiments one tailpipe extension260may located a spaced apart distance from the forward wall306of the enclosure212. A second tailpipe extension260may be located another spaced apart distance from the rearward wall310of the enclosure212. Each spaced apart distance may be substantially equal (e.g., within 5%), or may be different.

The three top surfaces270, including transition portions271(FIG. 6) may together define a top surface contour275(FIGS. 6 & 13) in the top portion250of the muffler210. A substantially circular center depression276(FIG. 13) may be formed in the top surface contour275defined by the spare-tire well218. Defined by the spare-tire well218may refer to, for example, locating and sizing the center depression276, which may also be referred to as a center cut, in accordance with the location and size of the spare tire well218for use with a particular make and model, and/or configuration of a vehicle.

In some embodiments one or more of the partitions254may include tabs disposed substantially perpendicular to a substantially vertical face thereof. The tabs may be fixed to a top and/or a bottom inner face of the enclosure212. The tabs may be bent portions of the partitions formed to protrude past a majority of an edge of the partitions254. The tabs may be formed integral with each partition in, for example, a stamping operation or the like. They may be bent in a separate operation. The tabs may be tack welded to the bottom surface282, and/or to the top surface280of the enclosure212. The tabs may serve to allow access to spot-weld the tabs to the inner bottom surface282of the bottom shell252. Then tabs may be projection welded to the upper shell250upon assembly. The partitions254may be made from sheet metal, or the like, or some other material. In some embodiments the partitions254may include opposite scalloped edges configured to fit adjacent to, or in contact with, the corrugated contours237of the respective top portion250and bottom portion252of the muffler210.

In one example, where the exhaust system includes exactly two exhaust pipes, the exhaust system carries exhaust from two respective banks of cylinders to the muffler. The muffler may include balance tubes, or crossover pipes, that may fluidically couple the tubes and provide some mixing of the sound waves from both banks. This may create a deeper more mellow tone from the engine, and may also tend to improve engine torque at lower rpm ranges.

It should be understood that the systems and methods described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are contemplated. Accordingly, the present disclosure includes all novel and non-obvious combinations of the various systems and methods disclosed herein, as well as any and all equivalents thereof.