Exhaust runner collar

Methods and systems are provided for a collar welded to a runner to manage stress in an exhaust manifold. In one example, a system may include welding a collar to a runner and a flange with an air gap located between the collar, the runner, and the flange.

FIELD

The present description relates generally to systems for an exhaust runner collar.

Engine performance may be increased by disabling exhaust gas communication between cylinders. This may be accomplished by an exhaust manifold comprising individual exhaust tubes (e.g., exhaust runners) for each cylinder. The exhaust runners remain separated, and therefore the exhaust gas remains separated before coming together at a collector. A longer separation can minimize exhaust pulse overlap and enable optimized valve timing.

However, exhaust runners are often longer with significant mass away from the engine in a cantilever configuration. Thus, the longer exhaust runners are prone to higher stress through a bending moment than other manifolds (e.g., cast iron log style exhaust manifolds). The higher stress increases a likelihood of degradation (e.g., single overload or fatigue cracking) at a junction between the exhaust runner and an inlet flange coupling the runner to the engine.

Other attempts to address stress in long exhaust runners include casting cores and adding brackets. Stress can also be managed through a welding geometry. One example approach is shown by Roussel et al. in U.S. Pat. No. 4,832,383. Therein, exhaust runners are welded to a flange of an engine in a circumferential direction via a chamfered weld. The weld allows the exhaust runner to more accurately fit into the inlet flange.

However, the inventors herein have recognized potential issues with such systems. As one example, the weld is unable to flex and/or bend under high engine vibration energy. Thus, the exhaust runner(s) are still prone to high stress generated via combustion and may result in a fatigue failure at the welded joint.

In one example, the issues described above may be addressed by a method for a runner having a runner wall interfacing with an inlet flange of a cylinder head and a collar positioned at the interface forming an annular air gap around an exterior of the runner. In this way, the collar may be able to flex in response to stresses generated by operating a vehicle and be less susceptible to a fatigue fracture and thus increase a longevity of the exhaust runner.

As one example, the collar is formed with a single wall extending from the inlet flange to the exhaust runner at respective positions spaced away from a corner of the interface. A geometry of the collar (e.g., L-shaped, I-shaped, square cross-section, and triangular cross-section) may increase stress load sharing via a spring-like flexibility of the collar. The air gap is interruptedly sealed at the respective positions via weld beads such that there are openings leading to the air gap from the engine or an ambient atmosphere. The air gap extends uninterruptedly fully around an outer circumference of the outer surface of the runner wall in one example. It will be appreciated by someone skilled in the art that the air gap may also be segmented (e.g., interrupted) according to a shape of the collar. In one embodiment, the collar may be welded to only a single runner of a plurality of runners in order to manage the stress across the runners. The single runner may be the shortest runner of the plurality of runners or a runner closest to a rear of a vehicle. Additionally or alternatively, the single runner may comprise a most acute bend or highest cantilever of the plurality of runners. In this way, the single runner, without the collar, may have a greatest likelihood of degradation compared to the plurality of runners. By welding the collar to the single runner, the collar may distribute a stress load received by the single runner such that the likelihood of degradation for the single runner is decreased.

DETAILED DESCRIPTION

The following description relates to a system for a collar coupled to an exhaust runner and an inlet flange. The collar is coupled to the inlet flange adjacent to an exhaust side of a combustion chamber of an engine, as shown inFIG. 1. An exhaust manifold ofFIG. 1comprising the collar is shown in more detail inFIG. 2. A close-up the collar coupled to the exhaust runner is shown inFIG. 3. A cross-section of the collar and the exhaust runner is shown inFIG. 4. A side-on two-dimensional view illustrating an air gap and shape of the collar is shown inFIGS. 5 and 6.

FIGS. 1-6show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example.

Turning now toFIG. 1, aspects of an example engine10are shown. Multi-cylinder engine10may be included in a propulsion system of an automobile. In the present example, engine10is shown in a V6 configuration, however further examples may include V8, V12, I4, I6, boxer, rotary, and additional engine configurations. Engine10may be a spark ignition engine or compression ignition engine (i.e., sparkless diesel engine).

Engine10may be controlled at least partially by a control system12including controller14and by input from sensors16and/or a vehicle operator18via an input device20. In this example, input device20includes an accelerator pedal (e.g., the input device20) and a pedal position sensor22for generating a proportional pedal position signal PP. Controller14outputs signals and commands to actuators24to control the operation of engine10and related systems.

A plurality of combustion chambers (cylinders)26is included in engine10, each including combustion chamber walls with a piston positioned therein. Engine10includes an engine block28coupled to cylinder heads30and32, the combustion chamber walls defined by the engine block28, first cylinder head30, and second cylinder head32. Each piston may be coupled to crankshaft34so that reciprocating motion of each piston is translated into rotational motion of the crankshaft34. Crankshaft34may be coupled to at least one drive wheel of a vehicle via an intermediate transmission system. Further, a starter motor may be coupled to crankshaft34via a flywheel to enable a starting operation of engine10.

Each combustion chamber26may receive intake air from an intake manifold via an intake passage (not shown) and may exhaust combustion gases via an exhaust manifold38. The intake manifold and exhaust manifold38can selectively communicate with combustion chambers26via respective intake valves and exhaust valves (not shown). In some embodiments, one or more of the combustion chambers26may include two or more intake valves and/or two or more exhaust valves. Engine intake valves and engine exhaust valves may be mechanically actuated (e.g., by an overhead cam), electro-magnetically actuated (e.g., EVA) or some combination of the two. Further, engine10may include port injection or direct injection in one or more of the plurality of combustion chambers26.

In the present example, a first exhaust manifold38is only coupled to a first cylinder bank of first cylinder head30. A second exhaust manifold (e.g., coupled to a second cylinder bank included in second cylinder head32) is not shown for the sake of simplicity. However, a second exhaust manifold in a “V” configuration engine may be provided. Furthermore, the second exhaust manifold coupled to the second cylinder head32may be substantially identical to the first exhaust manifold38or it may be substantially different in packaging or architecture. The first exhaust manifold38is coupled to exhaust system100. The second exhaust manifold may comprise a second exhaust system substantially similar to exhaust system100. In one example, the exhaust manifold38may be a fabricated tubular header style manifold. In another example, the exhaust manifold38may be a cast log style manifold.

Exhaust manifold38includes an inlet flange50between first ends of a plurality of runners48and the first cylinder head30. The exhaust runners48may be welded together to form the exhaust manifold38. The inlet flange50is physically coupled to the first ends of the runners48on a first side (e.g., side facing the exhaust manifold38). The inlet flange50is physically coupled to an exhaust side of the first cylinder head30via a second side, opposite the first side of the inlet flange50. The inlet flange50fluidly couples the runners48to corresponding combustion chambers26such that exhaust gas expelled from the combustion chambers26flows into one of the corresponding exhaust runners48.

Each of the runners48corresponds to an opening (e.g., an exhaust opening) of one of the cylinders26. In other words, the first cylinder head30having a plurality of cylinder openings, wherein at least one of the cylinder openings corresponds to at least one of the exhaust runners48. Each of the exhaust runners48of each of the cylinders26is separated from one another before leading to a common junction at a chamber (e.g., a collector)36. The collector36of the exhaust manifold38may include a cast housing. The housing may include an alloy of iron (e.g., nodular, ductile, etc), carbon, and a number of additives such as Si, Al, Cr, Mo, Ni, and Sn.

A second end of the runners48is physically coupled to the chamber36of the exhaust manifold38. The first end of the runners48is higher (e.g., above in the axial direction) than the second end of the runners48. In other words, for a vehicle placed on a flat surface, the first end of the runners48is axially higher than the second end of the runners48. In this way, the runners48may curve near the first end in order to decrease packaging constraints of the runners48. However, the runners48are susceptible to degradation (e.g., cracks) near the first end due to the curvature, length of installation, and mass supported by manifold flange56, as described above.

Each of the runners48may curve in a different manner toward the chamber36. Furthermore, each runner may also have a different length to achieve optimum engine performance through exhaust pressure wave tuning. Runners48may be a different length, such that the chamber36is proximal a first runner and distal to a last runner. In this way, the first runner may be increasingly curved compared to the last runner. Thus, the first runner may be more prone to degradation than the last runner, specifically if significant mass is supported at manifold flange56and the last runner is geometrically closest to manifold flange56. Alternatively, the first runner may be more prone to fatigue degradation due to its position relative to the dynamic excitation and supported mass.

Exhaust manifold38further includes a collar52located at a junction between one of the runners48and the inlet flange50. The collar52is welded via a weld to the first end of one the runners48and the inlet flange50. In one example, the exhaust manifold38comprises exactly one collar52coupled to exactly one of the runners48, where other runners do not have a welded collar. In this way, the collar52may be physically coupled to the runner48directly upstream of the bend/curvature at an exhaust side of the first cylinder head30. The collar52circumferentially surrounds the first end of one of the runners48and thus is circularly coupled to the inlet flange50. Additional details of the structure and function of the collar52will be described in greater detail below.

It will be appreciated by someone skilled in the art that one or more of the runners48may be coupled to a corresponding collar. Additionally or alternatively, all of the runners48may be coupled to a corresponding collar. In this way, a number of collars may be equal to a number of runners48. Additionally or alternatively, the collars of the one or more runners48may be structurally equivalent or inequivalent. If each of the collars is unequal, then the collars may be designed such that they increase a stress balance across all of the runners of the exhaust manifold.

It will also be appreciated by someone skilled in the art that the collar may not be a complete circumferential ring. The collar may be a series of gussets or partial rings spaced apart from one another around a circumference of the exhaust runner in order to distribute a stress load. Additionally the geometry of the collar may be a variety of cross sections including “I”, “L”, square, or triangular.

Combustion gas expelled from the combustion chambers26located in the first cylinder head30may be exhausted toward the runners48before being directed to the chamber36, where exhaust gas from each of the cylinder26merges and flows through an outlet passage54. The outlet passage54is distal from the runners48on an opposite side of the chamber36. In the present example, outlet passage54is parallel to the longitudinal axis. Additionally, the outlet passage54terminates with a manifold flange56. In the present example, a turbocharger casing flange41of turbocharger40is coupled to the manifold flange56to receive exhaust gas from the exhaust manifold38.

In the present example, turbocharger40is coupled to the exhaust manifold38at manifold flange56via turbocharger casing flange41. Turbocharger40includes a compressor (not shown) arranged along the intake passage and which may be at least partially driven by a turbine74(e.g., via a shaft) arranged in exhaust passage76. The compressor may also be at least partially driven by the engine (e.g., via crankshaft34) and/or an electric machine. Turbocharger40includes a bypass passage78with an inlet coupled downstream the turbocharger casing flange41and upstream of the turbine74. An outlet of the bypass passage78is coupled downstream of the turbine74and upstream of the aftertreatment system42. A wastegate80is disposed within the bypass passage78. The amount of compression provided to one or more cylinders26of the engine via turbocharger40may be varied by controller14through, for example, control of wastegate80. For example, the wastegate80may be actuated to a more closed position via signals sent from controller14to actuators24in order to provide a greater amount of compression.

In the present example, exhaust gas that passes through bypass passage78or turbine74flows to exhaust aftertreatment system42. Exhaust aftertreatment system42is disposed in exhaust passage76and may include a three-way catalyst (TWC), diesel oxidation catalyst, particulate filter (PF), selective catalytic reduction (SCR) catalyst, nitrogen oxide trap, sulfur oxide trap, hydrocarbon trap, or combinations thereof. Further examples of engine10may include one or both of a low pressure (LP) and a high pressure (HP) exhaust gas recirculation (EGR) loop, along with corresponding valves and sensors.

In one embodiment, additionally or alternatively, the turbocharger40, turbine74, and wastegate78may be omitted. The engine10may include only a compressor (e.g., a supercharger) coupled to one or more of a crankshaft and an auxiliary energy storage unit. In this way, exhaust gas may flow directly to exhaust aftertreatment system42without flowing through the turbine74or the wastegate78. Alternatively, the engine10may be a naturally-aspirating engine.

FIG. 1depicts a general schematic for an engine coupled to an exhaust manifold with various components located along an exhaust pathway.FIG. 2depicts a collar coupled to an inlet flange and an exhaust runner, which may be used in the engine system ofFIG. 1.

In an embodiment, exhaust runners with runner walls interfacing with an inlet flange may be adjacent a cylinder head. A collar may be positioned adjacent the interface between a shortest runner and the flange. The collar may form an annular gap around an exterior (e.g., the runner wall) of the runner. The collar may be formed with a single wall extending from the flange to the runner at respective positions spaced away from a corner of the interface, with no further walls exterior to the single wall of the collar. The annular gap may be sealed completely at the respective positions and there are no openings leading to the annular gap from an engine or an ambient environment. In another example, the annular gap may be sealed for a portion at the respective positions, where the annular gap is in fluid communication with the ambient environment. There may be only a single annular gap contained between the collar and an exterior surface of the runner wall. The annular gap extends uninterruptedly fully around an outer circumference of the outer surface of the runner wall. Alternatively, the collar may be segmented such that the annular gap extends interruptedly around the outer circumference of the outer surface of the runner wall.

The embodiment may further comprise, additionally or alternatively, a second, longer runner with another runner wall interfacing with the flange. The second runner does not comprise a collar. In this way, an overall stress caused by a weight and dynamic excitation of the exhaust runners is decreased compared to all the exhaust runners comprising a collar.

Turning now toFIG. 2, an exhaust system200comprising a portion of an exhaust manifold202is illustrated. The exhaust manifold202comprises an inlet flange204, holes206, exhaust runners207, a collar216, and a collector218. Exhaust runners207include a fourth exhaust runner208, a third exhaust runner210, a second exhaust runner212, and a first exhaust runner214. In one example, the fourth exhaust runner208may be a last exhaust runner, wherein the last exhaust runner is an exhaust runner furthest away from a front of a vehicle.

As described above, the inlet flange204is located between an exhaust side of a cylinder head and each of the runners207. The inlet flange204is physically coupled to the cylinder head via stud bolts extending through corresponding holes206. The stud bolts may be threaded through the holes206and into corresponding holes of the cylinder head in order to fasten the inlet flange204to the cylinder head. In this way, the inlet flange204is in face-sharing contact with and fixed to the cylinder head. In one example, there may be no intervening components located between the inlet flange204and the cylinder head. In another example, there may be a gasket for at least sealing between the inlet flange204and the cylinder head. Additionally or alternatively, coolant passages may be located in the cylinder head adjacent the inlet flange204.

Runners207extend through corresponding orifices matched in size to cylinder head ports of the inlet flange204and are fluidly coupled to corresponding cylinders. In this way, an engine (such as engine10shown inFIG. 1) coupled to the inlet flange204comprises at least four cylinders. In one example, the engine comprises exactly four cylinders. In another example, the engine comprises exactly eight cylinders, where four cylinders are in a first cylinder bank and the remaining four cylinders are in a second cylinder bank. Thus, as described above, there may be two inlet flanges with runners207, a first inlet flange with runners coupled to the first bank and a second inlet flange with runners coupled to the second bank.

Exhaust gas exiting combustion chambers of the engine may flow through the inlet flange204and into runners207. For example, a first cylinder may correspond to the first exhaust runner214. In this way, the exhaust gas from the first exhaust cylinder flows to only the first runner214and does not flow to the second, third, or fourth exhaust runners212,210, and208, respectively. Additionally, a second cylinder may correspond to the second exhaust runner212, a third cylinder may correspond to the third exhaust runner210, and a fourth cylinder may correspond to the fourth exhaust runner208, where exhaust gas from a respective cylinder flows to only a corresponding exhaust runner. As shown, the fourth exhaust runner208is the shortest of all runners of the manifold/engine, with the third runner210being the second shortest, the second runner212being the third shortest, and the first runner214being the longest. The fourth exhaust runner208may be increasingly prone to degradation due to thermal stress. Increased temperatures may cause the runners207to expand. However, shorter runners are not able to expand as effectively as longer runners (e.g., the expansion is distributed over a shorter length). As a result, the collar216is located on the highest stress runner (e.g., fourth exhaust runner208). In one example, the collar216is welded to only one of the plurality of exhaust runners (e.g., the fourth exhaust runner208of the plurality of exhaust runner207) in order to balance the stress across an entire exhaust manifold202.

In one example, the first exhaust runner214may be closest in proximity to a front of a vehicle. In this way, the fourth exhaust runner208may be the farthest from the front of the vehicle (e.g., closest to a rear of the vehicle).

Additionally or alternatively, a collar, such as collar216, may be located on an exhaust runner with a greatest curve (e.g., a most obtuse bend) or most cantilevered weight, both of which can lead to high stress. In this way, the exhaust manifold202may comprise one or more collars with each collar being differently installed with a different length and/or shape. A collar is located on the shortest exhaust runner and/or the runner with the greatest bend. In an alternative example, each of the runners207may be coupled to a collar such as collar216.

The collar216is welded to a surface of the inlet flange204. A cross-section of the weld between the collar216and the inlet flange204is triangular. The collar216is also welded to an outer circumference of the fourth runner208. The collar216is able to help the fourth runner208have a parallel (e.g., directed) path for stress that prevents overload or fatigue failure of fourth runner208. For example, the collar216receives a portion of stress directed toward the fourth runner208and redirects the stress in a linear direction parallel to a direction of the fourth runner208.

An entire circumference of the collar216may be uninterruptedly welded to an entire circumference of the fourth runner208and a surface of the inlet flange204. Alternatively, half of the entire circumference of the collar216may be uninterruptedly welded to the fourth runner208and a surface of the inlet flange204. Alternatively, the collar216may be interruptedly welded to the fourth runner208and the inlet flange204, such that welds are separated from one another. In one example, a weld may be a radian or less than a radian apart from an adjacent weld. Thus, the collar216may be in fluid communication with an ambient environment. As described above, degradation may occur at the junction between the inlet flange204and the fourth runner208due to the engine firing and the resulting dynamic excitation. By welding the collar216at the junction, the likelihood of degradation decreases due to the collar216being able to absorb a portion of stress experienced by the fourth runner208since a larger cross sectional area is available at a substantially equal stress level. The collar216is also able to bend and flex, similar to a leaf spring, due to an annular air gap located within the collar216. The above described flexible structure of the collar216further balances stress between the collar216and the fourth runner208. The structure of the collar216and the air gap will be described in greater detail below, such as with regard toFIGS. 3-5.

As the cylinders of the engine combust, both kinetic energy and thermal energy are transferred to the exhaust runners207. The collar216distributes the kinetic energy and thermal energy received by the fourth exhaust runner208in order to extend a longevity of the last exhaust runner208. The collar216distributes the kinetic motion by being able to flex due to the air gap. The collar216may retain its structural fidelity as thermal energy may not cross the air gap. For example, a shortest exhaust runner, similar to the last exhaust runner208, without a collar (e.g., collar216) may degrade after 75,000 engine cycles. The degradation may include cracks and/or holes, which may lead to exhaust leakage from the degraded runner. However, by welding the collar216to the shortest exhaust runner (e.g., the fourth exhaust runner208), the shortest exhaust runner may degrade after 500,000 engine cycles. Thus, the collar216extends the longevity of the shortest exhaust runner by over six fold.

Exhaust gas expelled from the engine cylinders flows through the exhaust runners207before flowing to the chamber220. The chamber220is coupled to each of the exhaust runners207via the collector218. In this way, exhaust gas from each cylinder of the engine is maintained separate in each of the exhaust runners207until the exhaust gas flow through the collector218and into the chamber220. Therefore, exhaust gas from each of the exhaust runners207mixes in the chamber220before flowing through an exhaust system (e.g., exhaust system100).

FIG. 2depicts an exhaust side of an inlet flange with a single exhaust runner physically coupled to a collar.FIG. 3depicts a more detailed illustration of the collar being welded to the single exhaust runner and the inlet flange.

Turning now toFIG. 3, a system300comprising an inlet flange302, an exhaust runner308, and a collar310is depicted. The inlet flange302, the exhaust runner308, and the collar310may be used as the inlet flange204, the fourth exhaust runner208, and the collar216in the embodiment ofFIG. 2and/or inlet flange50, the shortest of the runners48, and collar52of the embodiment ofFIG. 1, respectively.

The inlet flange302comprises an orifice matched to cylinder head port area, where the orifice is directly below a nut306. The orifice is threaded to receive the nut306in order to fasten the inlet flange302to a cylinder head (e.g., cylinder head30or cylinder head32). In this way, the inlet flange302is coupled to the exhaust side of the cylinder head. Thus, the inlet flange302experiences the vibrations and temperature changes created by the engine during combustion, which may also be experienced by the runner308.

In one embodiment, additionally or alternatively, a coolant jacket may be positioned between the inlet flange302and the cylinder head. Coolant in the coolant jacket may not flow to the inlet flange302. A stud bolt (e.g., nut306) may extend through an entirety of the coolant jacket and into a receiving hole of the cylinder head. In this way, the inlet flange302may be physically coupled to the coolant jacket and the cylinder head without receiving coolant from the coolant jacket.

The runner308is fluidly coupled to an exhaust pathway of a single cylinder of the cylinder head via the inlet flange302. The runner308is coupled to the inlet flange302. Thus, the runner308receives combustion products from the single cylinder of the engine and directs the combustion products to a remainder of an exhaust system (e.g., exhaust system100).

As described above, the runner308may be used as the fourth exhaust runner208ofFIG. 2. Thus, the runner308may be the shortest runner of a plurality of exhaust runners. Collar310is welded to the runner308and the inlet flange302to increase a longevity of the runner308. The collar310is depicted with an indentation in order to accommodate the nut306and its corresponding orifice. The collar310may comprise of one or more suitable materials capable of withstanding thermal energy and kinetic motion generated by operation of a vehicle. For example, the collar310may comprise of stainless steel, iron, copper, titanium alloys, nickel alloys, or other suitable compounds.

The collar310has an “L-shape” cross-section, as depicted. All of a portion of the collar310welded to the exhaust runner308extends annularly in an axial direction, perpendicular to a surface of the inlet flange302. All of a portion of the collar310welded to the inlet flange302extends annularly in a longitudinal direction, perpendicular to the exhaust runner308. A central portion312of the collar310is spaced away from a junction where the exhaust runner308and the inlet flange302are coupled. An annular air gap is located between an entire circumference of the junction and the collar310directly below the central portion312. The air gap may extend in the axial and longitudinal directions, similar to the collar310, however, to a lesser degree. In one embodiment, the air gap may be in fluid communication with an ambient environment such that air or other gases may flow in and out of the air gap freely. For example, the collar310may be open to the ambient environment near the nut306. The collar310may not be welded to the inlet flange302or the runner308at portions of the collar310in fluid communication with the ambient environment. The air gap will be described in further detail below with respect toFIG. 5.

FIG. 3depicts a close-up view of a collar welded to both a runner and an inlet flange.FIG. 4depicts a cross-section of the collar, the exhaust runner, and the inlet flange along the axial axis.

Turning now toFIG. 4, a cross-section400comprising an exhaust runner408being physically coupled to an inlet flange402by an interior weld404is illustrated. The cross-section is taken along the axial axis such that an interior of the inlet flange402, the runner408, and the collar410are depicted. An annular gap412is also depicted. The inlet flange402, nut406, runner408, and collar410may be used as inlet flange302, nut306, runner308, and collar310in the embodiment ofFIG. 3, respectively.

As described above, the inlet flange402is fastened to an exhaust side of a cylinder head via nut406. One or more stud bolts, including nut406, may be used to fasten the inlet flange402to the cylinder head.

The runner408extends into and is welded to the inlet flange402via the interior weld404. The interior weld404is located within an exhaust passage at a junction between an end of the runner408and an interior surface of the inlet flange402. The interior weld404is annular and welded to an entire circumference of the runner408and the interior surface of the inlet flange402. The interior weld404is beveled such that it does not alter an exhaust gas flow. The interface may be described as a corner (e.g., a 90° angle) created by inserting the runner408into a respective hole of the inlet flange402.

The collar410is a single wall extending from the inlet flange402and the runner408at first and second positions respectively. The first and second positions are spaced away from the runner408. The collar410extends around an entire circumference of the outer surface of the runner408. Weld beads414are used to weld portions of the collar410to portions of the first and second positions. The weld beads414are spaced apart such that the annular gap412, between the collar410, the runner408, and the inlet flange402, may remain in fluid communication with a surrounding ambient environment. Additionally, the collar410may maintain a degree of flexibility while being welded to both the runner408and the inlet flange402.

The weld beads414may be located around an entire circumference of the collar410, welded to both the runner408and the inlet flange402. The weld beads414coupled to the collar410and the runner408are not coupled to the inlet flange402. Likewise, weld beads414coupled to the collar410and the inlet flange402are not coupled to the runner408. Thus, there are two sets of weld beads414. Weld beads414may be spherical, triangular, rectangular, contoured, or other suitable shapes capable of welding the collar410to the runner408and the inlet flange402.

The annular gap412is annular and surrounds an entire circumference of the outer surface of the runner408. The annular gap412extends uninterruptedly around fully around the runner408. As described above, the annular gap412may be in fluid communication with the surrounding ambient environment. In this way, hotter gas from the ambient environment may flow out of the annular gap412and be replaced by cooler gas from the ambient environment. Cut-out416shows a region of the collar410contoured to accommodate the nut406. The collar410is spaced vertically away from the inlet flange402at a location of the cut-out416. Therefore, the cut-out may be an example of a location where the annular gap412is in fluid communication with the ambient environment. The cut-out416will be described in more detail with respect toFIG. 6.

The annular gap412may allow the collar410to flex and/or bend in response to stress. For example, as the engine combusts, kinetic motion may be transferred to the inlet flange402, the runner408, and the collar410. The collar410is designed to absorb a portion of stress received by the inlet flange402and the collar410by increasing the cross sectional area and acting as a spring (e.g., a leaf spring) in order to decrease a likelihood of degradation at the interface. The collar410may flex and/or bend between its first and second respective positions toward and away from the annular gap412.

As another example, thermal energy may be transferred to the inlet flange402, the runner408, and the collar410. The thermal energy may cause the inlet flange402, the runner408, and/or the collar410to thermally expand, which may lead to degradation. The collar410may be cooler than the inlet flange402and the runner408due to the annular gap412. In this way, the collar410, the runner408, and the inlet flange402may undergo heat transfer with the annular gap412in order to decrease a temperature increase due to combustion. By decreasing a temperature of the collar410, the runner408, and the inlet flange402, a life-expectancy of the aforementioned components may be increased. As described above, the increase may be five-fold.

FIG. 4depicts a three-dimensional cross-section of a collar welded to both an exhaust runner and an inlet flange.FIG. 5depicts a two dimensional cross-section of the collar, the runner, and the inlet flange along a longitudinal axis.

Turning now toFIG. 5, a side-on cross-section500of an inlet flange502, a runner504, a collar506, and an annular gap510are illustrated. The inlet flange502, the runner504, the collar506, and the annular gap510may be used as the inlet flange402, the runner408, the collar410, and the annular gap412in the embodiment ofFIG. 4.

The collar506is a single wall welded to a first point on an outer surface of the inlet flange502. Likewise, the collar506is welded to a second point on an outer surface of the runner504. As described above, the collar506is annular and surrounds an outer circumference of the runner504. As shown, a thickness of the runner wall504is thicker than a thickness of the collar506.

The collar506resembles a saddle-shape and is smoothly welded to the first and second points. For example, the collar506is beveled near the first and second points such that an acute angle is formed between the first point and the collar506and the second point and the collar506. Said another way, the collar506has convex and concave exterior surfaces to from a smooth connection between the runner504and the flange502. As a result, the collar506may be flexible.

The collar506comprises weld beads508A and508B near the first and second points, respectively. The weld bead508A couples the collar506to the flange502and the weld bead508B couples the collar506to the runner504. The weld beads508A and508B physically couple the collar506at the first and second points, respectively, while allowing the collar506flex and/or bend along a central portion adjacent the air gap510in order to dissipate a stress load created during engine operation.

Additionally or alternatively, the collar506may be a different geometrical cross-sections, including L-shaped, triangular, I-shaped, square, arched, contoured, and other suitable shapes. Furthermore, the collar506may not fully extend in a circumferential direction around the runner504. In one example, the collar506may be a plurality of segmented portions evenly or unevenly circumferentially spaced around the circumference of the runner504. In this way, a plurality of interrupted annular gaps510, equal to a number of collars506, may exist.

The annular gap510is located between the collar506, the inlet flange502, and the runner504. The annular gap510may be similarly shaped to the collar506. The annular gap510may be coupled to a greater area of the outer surface of the runner504compared to inlet flange502.

Turning now toFIG. 6, a side-on cross-section600of a flange602, a runner604, a collar606, an annular bead608, an annular gap610, a nut612, and a cut-out614is shown illustrating an open space. The inlet flange602, the runner604, the collar606, and the annular bead608may be used as flange502, runner504, collar506, and annular bead508A in the embodiment ofFIG. 5, and in this exampleFIGS. 5 and 6show the same components but at different cross-sections axially around the central axis of the runner.

The collar606is physically coupled to the flange602via the bead608. However, the collar606is not physically coupled to the runner604. The collar606is vertically spaced away from the runner604along the axial axis in order to accommodate the nut612. The collar606accommodates the nut612via the cut-out614. The annular gap610is in fluid communication with an ambient environment as a result of the cut-out614. The cut-out614may be defined by edges parallel to the axial axis or oblique to the axial axis. In this way, a collar spaced away from a corner of an interface between a flange and a runner may decrease a likelihood of degradation. An annular gap is located between the collar, the flange, and the runner, which may allow the collar to bend in response to absorbing a portion of a stress load at the interface. By doing this, the stress load received by the runner may be more evenly distributed. By coupling the collar to only a single runner of a plurality of runners, a weight load of the runners is decreased compared to a collar being coupled to all of the plurality of runners. The technical effect of coupling a collar to a single runner of a plurality of runners at an interface between a wall of the single runner and the flange is to decrease a likelihood of degradation.

BothFIGS. 5 and 6illustrate various faces of components directly contacting one another an in face-sharing contact (e.g., the bottom surface of506and the top surface of504at a crossectional location away from the nut), as well as certain surfaces not directly contacting one another (e.g., the bottom surface of606not contacting the top surface of604at the particular cross-sectional location at the nut612.

In a first example, the present application contemplates an exhaust system comprising a runner having a runner wall interfacing with an inlet flange of a cylinder head and a collar positioned at the interface forming an annular air gap around an exterior surface of the runner.

In a first embodiment, the exhaust system of the first example may include where the air gap is narrower along the wall of the runner than along the exhaust flange.

In a second embodiment, which optionally includes the first embodiment, the exhaust system of the first example may form the collar with a single wall extending from the flange to the runner at respective positions spaced away from a corner of the interface, with no further walls exterior to the single wall.

In a third embodiment, which optionally includes the first and second embodiments, the air gap may be sealed completely at the respective positions and there are no openings leading to the air gap from the engine or the ambient environment.

In a fourth embodiment, which optionally includes one or more of the first through third embodiments, the exhaust system of the first example further comprises an interior weld coupling the runner and the flange in an exhaust passage and not contacting the collar.

In a fifth embodiment, which optionally includes one or more of the first through fourth embodiments, the exhaust system of the first example further comprises a cylinder head having a coolant jacket therein, where no coolant of any coolant jacket in the cylinder head is fluidically coupled with the air gap.

In a sixth embodiment, which optionally includes one or more of the first through fifth embodiments, there is only a single air gap contained between the collar and the exterior surface of the runner wall.

In a seventh embodiment, which optionally includes one or more of the first through sixth embodiments, the collar has convex and concave exterior surfaces to form a smooth connection between the wall and the flange.

In an eighth embodiment, which optionally includes one or more of the first through seventh embodiments, the air gap extends uninterruptedly fully around an outer circumference of the exterior surface of the runner wall.

In a ninth embodiment, which optionally includes one or more of the first through eighth embodiments, a thickness of the collar wall is less than a thickness of the runner wall.

In a tenth embodiment, which optionally includes one or more of the first through ninth embodiments, the exhaust system of the first example further comprising another runner wall of another runner interfacing with the inlet flange, the another runner not having a collar and not having an air gap.

In an eleventh embodiment, which optionally includes one or more of the first through tenth embodiments, the another runner is longer in length leading to a junction at a collector than the runner.

In a twelfth embodiment, which optionally includes one or more of the first through eleventh embodiments, the exhaust system of the first example further comprises a cylinder head having a plurality of cylinder openings, wherein each exhaust runner of each cylinder is separated from one another before leading to a common junction at a collector.

In a thirteenth embodiment, which optionally includes one or more of the first through twelfth embodiments, each runner is bent differently.

In a fourteenth embodiment, which optionally includes one or more of the first through thirteenth embodiments, each runner is welded together with other runners to form an exhaust manifold.

In a second example, the present application contemplates a system comprising an annular collar welded around an entire circumference of an individual exhaust runner of a plurality of exhaust runners and an inlet flange on an exhaust side of a cylinder head, where the collar is spaced away from a corner of an interface between a wall of the exhaust runner and the inlet flange.

In a first embodiment, the system of the second example includes where the system additionally or alternatively includes an annular air gap located between the corner, the inlet flange, the exhaust runner, and the collar.

In a second embodiment, which optionally include the first embodiment, the collar is flexible.

In a third example, the present application contemplate a system comprising a plurality of separate exhaust runners fluidly coupled to respective cylinders via an inlet flange on an exhaust side of a cylinder head, where the plurality of exhaust runners are maintained separate upstream of a collector a collar circumferentially welded to a shortest runner of the plurality of exhaust runners and to the inlet flange, and an air gap located between the collar, the shortest runner, and the inlet flange, where the air gap is interruptedly sealed from an ambient atmosphere and an engine. In a first embodiment, the system of the third example includes where the system additionally or alternatively includes the collar is welded to the plurality of exhaust runners.