Patent Description:
The use of turbochargers in internal combustion engines is well known. Turbochargers increase the mass of air supplied to the engine thereby enabling the increase of the power output of the engine. In addition, the efficiency of the engine is increased by the turbocharger's utilization of the thermal energy contained in the engine's exhaust gases.

The connection between a turbocharger and the engine, however, may pose various design challenges. For the engine to operate at optimum efficiency, the engine must transfer as much energy as possible from the exhaust gases of the engine to a turbine of the turbocharger, thereby maximizing the boost provided by the turbocharger. Energy, however, is lost as the exhaust gases flow through the exhaust manifold and from the exhaust manifold into the turbocharger. Thus, the design of the exhaust passage in both the exhaust manifold and the turbine portion of the turbocharger are important to minimizing these energy losses.

Furthermore, as modem engines and engine systems become more complex and include more components, constraints on spacing between components on engines and constraints on the amount of space available for an engine in the engine compartment of work machines also increase. Thus, design challenges also exist regarding spacing constraints and assembly constraints.

<CIT> discloses a conventional prior art exhaust manifold outlet flange design that includes two generally rectangular ports separated by a dividing wall. <CIT> further discloses an alternative exhaust manifold outlet flange having two exhaust ports separated by a divider wall where the configuration of the pair of ports and divider wall resembles a bow tie. This configuration allows the ports to have the same area and the flange to maintain the same bolt pattern as the conventional rectangular port design while reducing the thermal inertia and stiffness of the surrounding constraining material of the flanges, thereby improving transient response and reducing thermal stress.

<CIT>, <CIT> and <CIT> show other examples of turbochargers having a turbine housing having an exhaust passage, an exhaust inlet port in fluid communication with the exhaust passage, and an exhaust inlet flange surrounding the exhaust inlet port, the exhaust inlet flange including a plurality of bolt holes arranged in a trapezoid-shaped bolt pattern. Furthermore, <CIT> Alrelates to a turbine housing having a housing body which is configured to accommodate a turbine wheel and which includes an inlet section forming an inlet flow passage for guiding exhaust gas to the turbine wheel, and an outlet section forming an outlet flow passage for discharging the exhaust gas from the turbine wheel; and at least one sleeve disposed along an inner wall surface of at least one of the inlet section or the outlet section of the housing body. The at least one sleeve includes a plurality of sections divided along a flow direction of the exhaust gas.

The present invention, relates to a turbocharger according to claim <NUM>.

Further features and advantages will be evident from the following illustrative embodiment which will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawings, in which:.

While the present disclosure describes certain embodiments of a turbocharger and exhaust manifold for an internal combustion engine, the present disclosure is to be considered exemplary and is not intended to be limited to the disclosed embodiments. Also, certain elements or features of embodiments disclosed herein are not limited to a particular embodiment, but instead apply to all embodiments of the present disclosure.

Referring to <FIG>, an exemplary embodiment of an internal combustion engine <NUM>, such as a diesel engine, is shown. The engine <NUM> may provide power to various types of applications and/or machines. For example, the engine <NUM> may power a machine such as an off-highway truck, a railway locomotive, an earth-moving machine, such as a wheel loader, excavator, dump truck, backhoe, motor grader, material handler, or the like. The term "machine" can also refer to stationary equipment like a generator that is driven by the engine <NUM> to generate electricity.

The engine <NUM> includes one or more cylinders <NUM> implemented therein. In the illustrated embodiment, the engine <NUM> includes six cylinders <NUM>. In other embodiments, however, the engine <NUM> may include more or less than six cylinders <NUM>. The engine <NUM> may be of an in-line type, as illustrated, a V-type, a rotary type, or other types known in the art. Each of the cylinders <NUM> may be configured to slidably receive a piston (not shown) therein.

Each of the cylinders <NUM> includes one or more intake ports <NUM>, each having an intake valve (not shown) and one or more exhaust ports <NUM>, each having an exhaust valve (not shown). The intake valve and the exhaust valve are configured to regulate fluid communication into and out of the cylinders <NUM> via the one or more intake ports <NUM> and the one or more exhaust ports <NUM>, respectively. The engine <NUM> includes an intake manifold <NUM> in fluid communication with one or more cylinders <NUM> and with an intake line <NUM> and an exhaust manifold <NUM> in fluid communication with the one or more cylinders <NUM> and with an exhaust line <NUM>. Intake air enters the one or more intake ports <NUM> from the intake line <NUM> via the intake manifold <NUM> and exhaust enters the exhaust line <NUM> from the one or more exhaust ports <NUM> via the exhaust manifold <NUM>. The exhaust manifold <NUM> is configured to mount onto one or more cylinder heads (not shown) on the engine <NUM>. In the illustrated embodiments, the exhaust manifold <NUM> and the one or more cylinder heads (not shown) are connected by a plurality of bolts <NUM> (<FIG>). However, other connection devices may be used, such as a plurality of studs and nuts.

The engine <NUM> includes a turbocharger <NUM> having an exhaust turbine portion <NUM> and an intake air compressor portion <NUM>. The compressor portion <NUM> includes an air inlet <NUM> and an air outlet <NUM>. The air outlet <NUM> is in fluid communication with the intake line <NUM>. The exhaust turbine portion <NUM> has an exhaust inlet <NUM> (<FIG>) and an exhaust outlet <NUM>. The exhaust outlet <NUM> is in fluid communication with the exhaust line <NUM>.

The exhaust inlet <NUM> of the turbocharger <NUM> includes an exhaust inlet flange <NUM> (i.e., the turbine foot) surrounding an exhaust inlet port <NUM>. The exhaust inlet flange <NUM> is configured to connect to an exhaust manifold outlet flange <NUM> on the exhaust manifold <NUM>. In the illustrated embodiment, the exhaust inlet flange <NUM> of the turbocharger <NUM> and the exhaust manifold outlet flange <NUM> of the exhaust manifold <NUM> are connected by a plurality of bolts <NUM> (<FIG>). However, other connection devices may be used, such as a plurality of studs and nuts. In the illustrated embodiment, a gasket <NUM> is positioned between the exhaust manifold outlet flange <NUM> and the exhaust inlet flange <NUM>. The gasket <NUM> has bolt holes (not shown) in the same bolt pattern as the exhaust manifold outlet flange <NUM> and the exhaust inlet flange <NUM>, which is described below in more detail.

Referring to <FIG>, the turbine portion <NUM> of the turbocharger <NUM> has a turbine housing <NUM> having one or more outer surfaces <NUM> and one or more inner surfaces <NUM>. The inner surfaces <NUM> define the exhaust inlet port <NUM> and a spiralling exhaust passage <NUM> (i.e., a volute) in fluid communication with the exhaust inlet port <NUM> and extending from the exhaust inlet port <NUM> to the exhaust outlet <NUM>. As shown in <FIG>, the exhaust passage <NUM> spirals about a central axis Y and the turbine housing <NUM> has a radius R that decreases as the exhaust passage <NUM> spirals inward.

In the illustrated embodiment, the inner surfaces <NUM> bounding the exhaust passage <NUM> are integral with and transition smoothly into the exhaust inlet flange <NUM> such that the exhaust passage <NUM> smoothly transitions into the exhaust inlet port <NUM>. The exhaust inlet flange <NUM> includes a planar end face <NUM>, an exterior surface <NUM> opposite the end face <NUM>, and a peripheral edge <NUM> connecting the end face <NUM> to the exterior surface <NUM>. As shown in <FIG>, the plane P defined by the planar end face <NUM> is a distance B1 from the central axis Y. The distance B1 represents the shortest distance between the plane P and the central axis Y. In some exemplary embodiments, the exhaust inlet flange <NUM> is in a tucked configuration. As used in this disclosure, an exhaust inlet flange <NUM> is "tucked" when the distance B1 is less than, or equal to, the radius R along the same radial line. An "extended" configuration is when the distance B1 is greater than the radius R along the same radial line (i.e., exhaust inlet flange <NUM> extends beyond the turbine housing <NUM>).

In some exemplary embodiments, the distance B <NUM> is less than <NUM>% of the radius R along the same radial line, or is less than <NUM>% of the radius R along the same radial line, or is less than <NUM> % of the radius R along the same radial line. In one exemplary embodiment, the exhaust inlet flange <NUM> is a distance B <NUM> in the range of <NUM>% to <NUM>% of the radius R along the same radial line.

In the illustrated embodiment, the peripheral edge <NUM> includes a first outer edge <NUM>, a second outer edge <NUM> parallel to and opposite the first outer edge <NUM>, a third outer edge <NUM> extending between the first outer edge <NUM> and the second outer edge <NUM>, and a fourth outer edge <NUM> parallel to and opposite the third outer edge <NUM> and extending between the first outer edge <NUM> and the second outer edge <NUM>. With respect to the direction that the exhaust passage <NUM> spirals, the first outer edge <NUM> is at an inner side <NUM> of the turbine housing <NUM> and the second outer edge <NUM> is at an outer side <NUM> of the turbine housing <NUM>.

The second outer edge <NUM> transitions to the third outer edge <NUM> via a first rounded corner <NUM> and transitions to the fourth outer edge <NUM> via a second rounded corner <NUM>. The first outer edge <NUM> transitions to the third outer edge <NUM> via a third rounded corner <NUM> and transitions to the fourth outer edge <NUM> via a fourth rounded corner <NUM>. The third rounded corner <NUM> and the fourth rounded corner <NUM> extend laterally outward of the third outer edge <NUM> and the fourth outer edge <NUM>, respectively.

The exhaust inlet flange <NUM> includes a plurality of bolt holes for mounting the turbocharger <NUM> to the exhaust manifold <NUM>. In the illustrated embodiment, a first hole <NUM> is positioned adjacent the first rounded corner <NUM>, a second hole <NUM> is positioned adjacent the second rounded corner <NUM>, a third hole <NUM> is positioned adjacent the third rounded corner <NUM>, a fourth hole <NUM> is positioned adjacent the fourth rounded corner <NUM>. The first hole <NUM> is centered on a first axis <NUM> that extends perpendicular to the end face <NUM>, the second hole <NUM> is centered on a second axis <NUM> that extends perpendicular to the end face <NUM>, the third hole <NUM> is centered on a third axis <NUM> that extends perpendicular to the end face <NUM>, and the fourth hole <NUM> is centered on a fourth axis <NUM> that extends perpendicular to the end face <NUM>.

In the illustrated embodiment, the third axis <NUM> is a first distance D1 from the fourth axis <NUM>, the first axis <NUM> is a second distance D2 from the second axis <NUM>, the first axis <NUM> is a third distance D3 from the third axis <NUM>, and the second axis <NUM> is a fourth distance D4 from fourth axis <NUM>. In the exemplary embodiment, the first distance D1 is greater than the second distance D2 and the third distance D3 is equal to the fourth distance D4. In the exemplary embodiment, a first line intersecting the first axis <NUM> and the second axis <NUM> is parallel to a second line intersecting the third axis <NUM> and the fourth axis <NUM>. Thus, the bolt pattern for the exhaust inlet flange <NUM> takes the shape of a trapezoid.

In one exemplary embodiment, the first distance D1 is in the range of <NUM> to <NUM>, or <NUM> and the second distance D2 is in the range of <NUM> to <NUM>, or <NUM>. Thus, the ratio of the first distance D1 to the second distance D2 is in the range of <NUM> to <NUM>, or <NUM>. The third distance D3 and the fourth distance D4 are in the range of <NUM> to <NUM>, or <NUM>.

In an exemplary embodiment, the exhaust inlet port <NUM> is a single, open port that is symmetric about a central axis A. Thus, the exhaust inlet port <NUM> is not divided into two ports by a dividing wall and is the sole exhaust inlet port for the turbocharger <NUM>. In other embodiments, however, the exhaust inlet port <NUM> may not be symmetric about the central axis A. The exhaust inlet port <NUM> includes a first linear portion <NUM>, a second linear portion <NUM> spaced apart from and parallel to the first linear portion <NUM>, a third linear portion <NUM> perpendicular to and extending between the first linear portion <NUM> and the second linear portion <NUM>, and a fourth linear portion <NUM> parallel to the third linear portion <NUM> and perpendicular to and extending between the first linear portion <NUM> and the second linear portion <NUM>.

The first linear portion <NUM> transitions to the third linear portion <NUM> via a first inner rounded corner <NUM> and transitions to the fourth linear portion <NUM> via a second inner rounded corner <NUM>. The second linear portion <NUM> transitions to the third linear portion <NUM> via a first angled portion <NUM> positioned between a pair of first shallow curved portions <NUM> and transitions to the fourth linear portion <NUM> via a second angled portion <NUM> positioned between a pair of second shallow curved portions <NUM>. In some exemplary embodiments, the first angled portion <NUM> forms an angle relative to the second linear portion <NUM> in the range of <NUM> degrees to <NUM> degrees, or <NUM> degrees to <NUM> degrees, or <NUM> degrees.

The first linear portion <NUM> has a first length L1, the second linear portion <NUM> has a second length L2, the third linear portion <NUM> has a third length L3, and the fourth linear portion <NUM> has a fourth length L4. In the exemplary embodiment, the third length L3 is equal to the fourth length L4. Further, as a result of the first angled portion <NUM> and the second angled portion <NUM>, the second length L2 is less than the first length L1. Thus, with respect to the direction that the exhaust passage <NUM> spirals, the linear portion of the exhaust inlet port <NUM> adjacent the inner side is longer than the linear portion of the exhaust inlet port <NUM> adjacent the outer side. In one exemplary embodiment, the ratio of the first length L1 to the second length L2 is in the range of <NUM> to <NUM> or <NUM>.

The one or more outer surfaces <NUM> of the turbine housing <NUM> may be configured to avoid interference between the turbine housing <NUM> and an installation tool, such as for example, a socket for installing the bolts <NUM>, and provide enough clearance to make attaching of the turbocharger <NUM> to the exhaust manifold <NUM> easier for an installer. Referring to <FIG>, in one exemplary embodiment, the one or more outer surfaces <NUM> of the turbine housing <NUM> may include one or more recessed, concave, or indented surface areas adjacent to one or more of the first axis <NUM>, the second axis <NUM>, the third axis <NUM>, and the fourth axis <NUM>. For example, the turbine housing <NUM> may have portions of its outer surface <NUM> that are recessed, such as for example, one or more grooves. The recessed portions may extend along a portion of the outer surfaces <NUM> parallel to one or more of the first axis <NUM>, the second axis <NUM>, the third axis <NUM>, and the fourth axis <NUM>.

In the exemplary embodiment, the turbine housing <NUM> includes a first recessed portion <NUM> adjacent the first hole <NUM>, a second recessed portion <NUM> adjacent the second hole <NUM>, a third recessed portion <NUM> adjacent the third hole <NUM>, and a fourth recessed portion <NUM> adjacent the fourth hole <NUM>. Each of the holes <NUM>, <NUM>, <NUM>, <NUM> has an assembling clearance defined as the closest radial distance between the central axis of the hole and a surface of the turbine housing at a position along the central axis that is exterior to the hole. In other words, the assembling clearance is associated with the clearance between the turbine housing and an installation tool, such as a socket or socket extension, used to drive the bolts <NUM> to attach the turbocharger <NUM> to the exhaust manifold <NUM>.

As shown in <FIG>, the first hole <NUM> has a first assembling clearance C1, the second hole <NUM> has a second assembling clearance C2, the third hole <NUM> has a third assembling clearance C3, and the fourth hole <NUM> has a fourth assembling clearance C4. In the illustrated embodiments, the assembling clearances C1-C4 (i.e., the closest radial distance between the central axis of each of the holes and a surface of the turbine housing) are at the recessed portions <NUM>, <NUM>, <NUM>, <NUM> for each of the holes <NUM>, <NUM>, <NUM>, <NUM>. In other embodiments, however, one or more of the assembling clearances may be at other portions of the turbine housing <NUM>. In some exemplary embodiments, each of the assembling clearances C1-C4 is greater than <NUM>, or greater than <NUM>, or greater than <NUM>.

Referring to <FIG>, in the illustrated embodiment, the exhaust manifold <NUM> has a central manifold portion <NUM> in fluid communication with a first pair of the cylinders <NUM>, a first lateral manifold portion <NUM> in fluid communication with a second pair of the cylinders <NUM>, and a second lateral manifold portion <NUM> opposite the first lateral manifold portion <NUM> and in fluid communication with a third pair of the cylinders <NUM>.

Referring to <FIG>, the central manifold portion <NUM> of the exhaust manifold <NUM> has a generally cylindrical, tubular body <NUM> having an outer surface <NUM> and an inner surface <NUM> defining an exhaust outlet port <NUM> and an exhaust passage <NUM> in fluid communication with the exhaust outlet port <NUM>.

In the illustrated embodiment, the inner surface <NUM> bounding the exhaust passage <NUM> is integral with and transition smoothly into the exhaust manifold outlet flange <NUM> such that the exhaust passage <NUM> smoothly transitions into the exhaust outlet port <NUM>. The exhaust manifold outlet flange <NUM> includes a planar end face <NUM>, an exterior surface <NUM> opposite the end face <NUM>, and a peripheral edge <NUM> connecting the end face <NUM> to the exterior surface <NUM>. In the illustrated embodiment, the peripheral edge <NUM> includes a first outer edge <NUM>, a second outer edge <NUM> parallel to and opposite the first outer edge <NUM>, a third outer edge <NUM> extending between the first outer edge <NUM> and the second outer edge <NUM>, and a fourth outer edge <NUM> opposite the third outer edge <NUM> and extending between the first outer edge <NUM> and the second outer edge <NUM>.

The second outer edge <NUM> transitions to the third outer edge <NUM> via a first rounded corner <NUM> and transitions to the fourth outer edge <NUM> via a second rounded corner <NUM>. The first outer edge <NUM> transitions to the third outer edge <NUM> via a third rounded corner <NUM> and transitions to the fourth outer edge <NUM> via a fourth rounded corner <NUM>.

The exhaust manifold outlet flange <NUM> includes a plurality of bolt holes for mounting the turbocharger <NUM> to the exhaust manifold <NUM>. In the illustrated embodiment, a first hole <NUM> is positioned adjacent the first rounded corner <NUM>, a second hole <NUM> is positioned adjacent the second rounded corner <NUM>, a third hole <NUM> is positioned adjacent the third rounded corner <NUM>, and a fourth hole <NUM> is positioned adjacent the fourth rounded corner <NUM>. The first hole <NUM> is centered on a first axis <NUM> that extends perpendicular to the end face <NUM>, the second hole <NUM> is centered on a second axis <NUM> that extends perpendicular to the end face <NUM>, the third hole <NUM> is centered on a third axis <NUM> that extends perpendicular to the end face <NUM>, and the fourth hole <NUM> is centered on a fourth axis <NUM> that extends perpendicular to the end face <NUM>.

In the illustrated embodiment, the first axis <NUM> is a first distance E1 from the second axis <NUM>, the third axis <NUM> is a second distance E2 from the fourth axis <NUM>, the first axis <NUM> is a third distance E3 from the third axis <NUM>, and the second axis <NUM> is a fourth distance E4 from fourth axis <NUM>. In the exemplary embodiment, the first distance E1 is less than the second distance E2 and the third distance E3 is equal to the fourth distance E4. In the exemplary embodiment, a first line intersecting the first axis <NUM> and the second axis <NUM> is parallel to a second line intersecting the third axis <NUM> and the fourth axis <NUM>. Thus, the bolt pattern for the exhaust manifold outlet flange <NUM> takes the shape of a trapezoid. Likewise, the third outer edge <NUM> and the fourth outer edge <NUM> taper inward from the first outer edge <NUM> to the second outer edge <NUM>; thus, the outer edges of the exhaust manifold outlet flange <NUM> also take the shape of a trapezoid.

In one exemplary embodiment, the first distance E1 is in the range of <NUM> to <NUM>, or <NUM> and the second distance E2 is in the range of <NUM> to <NUM>, or <NUM>. Thus, the ratio of the first distance E1 to the second distance E2 is in the range of <NUM> to <NUM>, or <NUM>. The third distance E3 and the fourth distance E4 are in the range of <NUM> to <NUM>, or <NUM>.

In an exemplary embodiment, the exhaust outlet port <NUM> is a single, open port that is symmetric about a central axis B. Thus, the exhaust outlet port <NUM> is not divided into two ports by a dividing wall and is the sole exhaust outlet port for the exhaust manifold <NUM>. In other embodiments, however, the exhaust outlet port <NUM> may not be symmetric about the central axis B. The exhaust outlet port <NUM> includes a first linear portion <NUM> and a second linear portion <NUM> collinear to the first linear portion <NUM> and separated from the first linear portion <NUM> by a first inward curved portion <NUM>. The exhaust outlet port <NUM> further includes a third linear portion <NUM> opposite and parallel to the first linear portion <NUM> and a fourth linear portion <NUM> opposite and parallel to the second linear portion <NUM>. The third linear portion <NUM> is collinear to the fourth linear portion <NUM> and separated from the fourth linear portion <NUM> by a second inward curved portion <NUM>.

The exhaust outlet port <NUM> further includes a fifth linear portion <NUM> perpendicular to and extending between the first linear portion <NUM> and the third linear portion <NUM>, and a sixth linear portion <NUM> parallel to the fifth linear portion <NUM> and perpendicular to and extending between the second linear portion <NUM> and the fourth linear portion <NUM>.

The first linear portion <NUM> transitions to the fifth linear portion <NUM> via a first inner rounded corner <NUM> and the second linear portion <NUM> transitions to the sixth linear portion <NUM> via a second inner rounded corner <NUM>. The third linear portion <NUM> transitions to the fifth linear portion <NUM> via a first angled portion <NUM> and the fourth linear portion <NUM> transitions to the sixth linear portion <NUM> via a second angled portion <NUM>.

The central manifold portion <NUM> includes one or more cylinder head mounting flanges for mounting the central manifold portion <NUM> to the one or more cylinder heads (not shown) of the engine <NUM>. In the illustrated embodiment the central manifold portion <NUM> includes a first cylinder head mounting flange <NUM> and a second cylinder head mounting flange <NUM>. The first cylinder head mounting flange <NUM> includes a planar end face <NUM>, an exterior surface <NUM> opposite the end face <NUM>, and a peripheral edge <NUM> connecting the end face <NUM> to the exterior surface <NUM>. The first cylinder head mounting flange <NUM> further includes a first end <NUM> and a second end <NUM> opposite the first end <NUM>.

The first cylinder head mounting flange <NUM> includes a pair of bolt holes for mounting the central manifold portion <NUM> to a cylinder head (not shown). In the illustrated embodiment, a first hole <NUM> is positioned adjacent at the first end <NUM> and a second hole <NUM> is positioned adjacent the second end <NUM>. The first hole <NUM> is centered on a first axis <NUM> that extends perpendicular to the end face <NUM> and the second hole <NUM> is centered on a second axis <NUM> that extends perpendicular to the end face <NUM>.

The second cylinder head mounting flange <NUM> is substantially similar to the first cylinder head mounting flange <NUM>. The second cylinder head mounting flange <NUM> includes a planar end face <NUM>, an exterior surface <NUM> opposite the end face <NUM>, and a peripheral edge <NUM> connecting the end face <NUM> to the exterior surface <NUM>. The second cylinder head mounting flange <NUM> further includes a first end <NUM> and a second end <NUM> opposite the first end <NUM>.

The second cylinder head mounting flange <NUM> includes a pair of bolt holes for mounting the central manifold portion <NUM> to a cylinder head (not shown). In the illustrated embodiment, a first hole <NUM> is positioned adjacent at the first end <NUM> and a second hole <NUM> is positioned adjacent the second end <NUM>. The first hole <NUM> is centered on a first axis <NUM> that extends perpendicular to the end face <NUM> and the second hole <NUM> is centered on a second axis <NUM> that extends perpendicular to the end face <NUM>.

As shown in <FIG>, the planar end face <NUM> of the exhaust manifold outlet flange <NUM> extends at an angle α relative to the planar end face <NUM> of the second cylinder head mounting flange <NUM>. In the illustrated embodiment, the angle is in the range of <NUM> degrees to <NUM> degrees, or <NUM> degrees. In other embodiments, however, the angle may be greater than <NUM> degrees or less than <NUM> degrees.

The outer surface <NUM> of the central manifold portion <NUM> may be configured to avoid interference between the central manifold portion <NUM> and an installation tool, such as for example, a socket for installing the bolts <NUM>, and provide enough clearance to attach of the central manifold portion <NUM> to one or more cylinder heads (not shown) easier for an installer. Referring to <FIG> and <FIG>, in one exemplary embodiment, the outer surface <NUM> of the central manifold portion <NUM> may include one or more recessed, concave, or indented surface areas adjacent to one or more of the first axes <NUM>, <NUM> and/or one or more of the second axis <NUM>, <NUM>. In one exemplary embodiment, the outer surface <NUM> cylindrical, tubular body <NUM> of the central portion includes one or more recessed, concave, or indented surface portions.

In the exemplary embodiment, the central manifold portion <NUM> includes a first recessed portion <NUM> adjacent the first hole <NUM> of the first cylinder head mounting flange <NUM>, a second recessed portion <NUM> adjacent the second hole <NUM> of the first cylinder head mounting flange <NUM>, a third recessed portion <NUM> adjacent the first hole <NUM> of the second cylinder head mounting flange <NUM>, and a fourth recessed portion <NUM> adjacent the second hole <NUM> of the second cylinder head mounting flange <NUM>. Each of the holes <NUM>, <NUM>, <NUM>, <NUM> has an assembling clearance defined as the closest radial distance between the central axis of the hole and an outer surface of the central manifold portion <NUM> or an outer surface of the turbine housing <NUM> when assembled to the central manifold portion <NUM>, at a position along the central axis that is exterior to the hole. In other words, the assembling clearance is associated with the clearance between the central manifold portion <NUM> or turbine housing <NUM> and an installation tool, such as a socket or socket extension, used to drive the bolts <NUM> to attach the central manifold portion <NUM> to the one or more cylinder heads (not shown).

As shown in <FIG>, the first hole <NUM> of the first cylinder head mounting flange <NUM> has a first assembling clearance D1, the second hole <NUM> of the first cylinder head mounting flange <NUM> has a second assembling clearance D2, the first hole <NUM> of the second cylinder head mounting flange <NUM> has a third assembling clearance D3, and the second hole <NUM> of the second cylinder head mounting flange <NUM> has a fourth assembling clearance D4. In the illustrated embodiments, the assembling clearances D1-D4 (i.e., the closest radial distance between the central axis of each of the holes and a surface of the central manifold portion) are at the recessed portions <NUM>, <NUM>, <NUM>, <NUM> for each of the holes <NUM>, <NUM>, <NUM>, <NUM>. In other embodiments, however, one or more of the assembling clearances may be at other portions of the central manifold portion <NUM>. In some exemplary embodiments, each of the assembling clearances D1-D4 is greater than <NUM>, or greater than <NUM>, or greater than <NUM>.

Engines utilizing the turbocharger and exhaust manifold of the present disclosure can be used in a variety of applications, such as for example, to provide power to an off-highway truck, a railway locomotive, an earth-moving machine, an engine-driven generator or pumping system, or other engine-powered applications. The disclosed turbocharger and exhaust manifold are particularly well-suited for applications where spacing for the turbocharger and the exhaust manifold is constrained. For example, the turbocharger may include a tucked exhaust inlet flange which provides more compact spacing between the turbocharger and the exhaust manifold.

A more compact turbocharger and the exhaust manifold arrangement, however, can present challenges with assembly. For example, a conventional rectangular exhaust inlet flange may result in interference between an installation tool, such as a socket and a socket extension, and an exterior surface of the turbine housing and/or the exhaust manifold.

The turbocharger and the exhaust manifold of the present disclosure may include one or more features preventing interference between an installation tool and an exterior surface of the turbine housing and/or the exhaust manifold. For example, the turbine exhaust inlet flange may have novel configuration including a four hole, non-square bolt pattern with a narrower spacing between bolts on the outer side of the exhaust inlet flange, with respect to the direction that the exhaust passage spirals. The narrower spacing of the outer edge bolt holes provides additional clearance for access when bolting the turbocharger to the exhaust manifold.

The exhaust inlet port is configured to accommodate narrower spacing of the outer edge bolt holes while still being of sufficient size and design for adequate exhaust flow to the turbine. For example, the linear portion of the exhaust inlet port adjacent the inner side may be longer than the linear portion of the exhaust inlet port adjacent the outer side. Thus, the exhaust inlet port is wider adjacent the inner side than adjacent the outer side.

In addition, the recessed portions in the outer surfaces of the turbine housing and the outer surfaces of the exhaust manifold provide additional space for a socket or socket extension to engage and drive the bolts attaching the exhaust manifold to the cylinder heads and attaching the turbocharger to the exhaust manifold.

Claim 1:
A turbocharger (<NUM>), comprising:
a turbine housing (<NUM>) having an outer surface (<NUM>) and an inner surface (<NUM>) defining an exhaust passage (<NUM>);
an exhaust inlet port (<NUM>) in fluid communication with the exhaust passage (<NUM>); and
a tucked exhaust inlet flange (<NUM>) surrounding the exhaust inlet port (<NUM>), the exhaust inlet flange (<NUM>) including a plurality of bolt holes (<NUM>) arranged in a trapezoid-shaped bolt pattern, wherein the tucked exhaust inlet flange (<NUM>) has a planar end face (<NUM>) defining a first plane (P) and the turbine housing (<NUM>) circumscribes a central axis (Y), and wherein a shortest distance (B1) between the first plane (P) and the central axis (Y) along a first line is less than, or equal to, a radius (R) of the turbine housing (<NUM>) along the first line
wherein the tucked exhaust inlet flange (<NUM>) comprises an outer side (<NUM>) having a first bolt hole (<NUM>) centered on a first axis (<NUM>) and a second bolt hole (<NUM>) centered on a second axis (<NUM>) and an inner side (<NUM>) having third bolt hole (<NUM>) centered on a third axis (<NUM>) and a fourth bolt hole (<NUM>) centered on a fourth axis (<NUM>), wherein the third axis (<NUM>) is a first distance (D1) from the fourth axis (<NUM>) and the first axis (<NUM>) is a second distance (D2) from the second axis (<NUM>), and wherein the first distance (D1) is greater than the second distance (D2), and
wherein the exhaust inlet port (<NUM>) includes a first linear portion (<NUM>) adjacent the inner side (<NUM>) and a second linear portion (<NUM>), parallel to the first linear portion (<NUM>), and adjacent the outer side (<NUM>), wherein the first linear portion (<NUM>) has a first length (L1) and the second linear portion (<NUM>) has a second length (L2) that is less than the first length (L1)