Motor vehicle on which a vehicle engine is mounted

A motor vehicle (100) on which a vehicle engine (1) is mounted is described, the vehicle engine (1) including: an exhaust purification system (70) housing a GPF device (73) for purifying exhaust gas; and an EGR passage (52) connected to a portion of the exhaust purification system located downstream of the GPF device, and the engine is mounted in an engine compartment (R) defined in a front portion of a vehicle body. The exhaust purification system is located forward of a dash panel (103) constituting the engine compartment, and is positioned to extend toward a tunnel portion (T) of the dash panel. An upstream end portion (52c) of the EGR passage is connected to a lower portion of the exhaust purification system in a vertical direction of the vehicle.

TECHNICAL FIELD

The present disclosure relates to a motor vehicle on which a vehicle engine is mounted.

BACKGROUND ART

Patent Document 1 discloses, as an example of a vehicle engine, an engine including a purification unit (three-way catalyst) that purifies exhaust gas, and an EGR passage (EGR passage) that branches off from a portion of an exhaust passage downstream of the purification unit to be connected to an intake passage.

In the engine configured in this manner, burned gas returns to the intake passage after passing through the purification unit, and thus, a deposit component in external EGR gas can be reduced.

CITATION LIST

Patent Document

SUMMARY OF THE INVENTION

Technical Problem

When the engine described in Patent Document 1 is mounted in a front portion of a vehicle body, at least part of its exhaust passage is located at a rear portion of the engine compartment. In this case, if the engine is a rear exhaust engine, in particular, the purification unit connected to the exhaust passage is also located at the rear portion of the engine compartment.

On the other hand, as described above, the EGR passage branches off from the exhaust passage downstream of the purification unit. Thus, an upstream end portion of the EGR passage becomes close to the rear end of the engine compartment because the purification unit is located at the rear portion of the engine compartment. Therefore, the upstream end portion becomes close to a vehicle structure including a partition wall (e.g., a dash panel) that serves as a rear surface of the engine compartment, in particular, a tunnel portion of the partition wall.

In recent years, when an elaboration is made to the configuration of the engine to downsize the engine, for example, the EGR passage is required to be positioned as far as possible from the vehicle structure.

In view of the foregoing background, an object of the present disclosure is to provide a vehicle engine which is downsized and in which an EGR passage and a vehicle structure are positioned apart from each other.

Solution to the Problem

The present disclosure relates to a motor vehicle on which a vehicle engine is mounted, the vehicle engine including: an exhaust purifier housing a purification unit that purifies exhaust gas; and an EGR passage connected to a portion of the exhaust purifier located downstream of the purification unit, the vehicle engine being mounted in an engine compartment defined in a front portion of a vehicle body.

The exhaust purifier is positioned forward of a partition wall in a longitudinal direction of a vehicle, and extends toward a tunnel portion extending rearward from the partition wall in the longitudinal direction of the vehicle, the partition wall defining a rear portion of the engine compartment, and an upstream end portion of the EGR passage is connected to a lower portion of the exhaust purifier in a vertical direction of the vehicle.

According to this configuration, the exhaust purifier that houses the purification unit is positioned in front of the tunnel portion of the partition wall, which is a vehicle structure, to extend toward the tunnel portion, without being inserted into the tunnel portion. Therefore, compared to the configuration in which the exhaust purifier is inserted into the tunnel portion, the dimension of the engine in the longitudinal direction of the vehicle can be shortened, and by extension, the engine can be downsized.

The tunnel portion is generally formed by a ceiling surface that projects upward. Then, connecting the EGR passage to the lower portion of the exhaust purifier as described above can further block the upstream end portion of the EGR passage from approaching the ceiling surface as compared to the case where the EGR passage is connected to an upper portion of the exhaust purifier, for example.

This can downsize the engine, and can position the EGR passage and the vehicle structure apart from each other.

The partition wall may have an inclined portion inclined downward toward a rear side in the longitudinal direction of the vehicle. The upstream end portion of the EGR passage may be connected to a rear end portion of the exhaust purifier in the longitudinal direction of the vehicle. The upstream end portion of the EGR passage may be positioned below an upper end of the inclined portion in a vehicle height direction when viewed from the side of the vehicle.

According to this configuration, the upstream end portion of the EGR passage can be positioned in front of the inclined portion. Taking the rearward inclination of the inclined portion into account, the upstream end portion of the EGR passage can be positioned apart from the partition wall in accordance with the inclination angle.

The upstream end portion of the EGR passage may be positioned to overlap with the tunnel portion when viewed from the front side or rear side of the vehicle.

According to this configuration, if the engine is moved immediately behind upon collision of the vehicle, for example, the upstream end portion of the EGR passage goes back to fit in the tunnel portion.

Further, the exhaust purifier may be provided with a delivering portion to which the upstream end portion of the EGR passage is connected, and the delivering portion may be configured to project outward in a vehicle width direction.

This configuration advantageously makes the delivering portion apart from the partition wall, and by extension, an inner wall surface of the tunnel portion.

Specifically, for example, if the delivering portion projects upward in the vehicle height direction, the delivering portion becomes close to the ceiling surface described above, i.e., projects in a direction toward the partition wall, which is disadvantageous.

On the other hand, if the delivering portion projects downward in the vehicle height direction, the delivering portion is spaced apart from the partition wall, and also from the ceiling surface. In this case, however, moisture contained in the burned gas is accumulated at the lower end of the delivering portion. This configuration is also disadvantageous because the moisture may contain components that cause corrosion of metals.

The delivering portion can be configured to project rearward in the longitudinal direction of the vehicle. However, this configuration may bring the delivering portion closer to the partition wall. In addition, the distance between the delivering portion and the EGR passage increases in the longitudinal direction of the vehicle, which is disadvantageous also from the viewpoint of the downsizing of the engine.

In another configuration, the delivering portion can be configured to project forward in the longitudinal direction of the vehicle. However, this configuration may increase the curvature of a passage from the casing to the delivering portion, depending on the shape of the casing in which the purification unit is housed. This may be disadvantageous from the viewpoint of reduction of a flow path resistance.

Therefore, as described above, the delivering portion, projecting outward in the vehicle width direction, can be blocked from approaching the partition wall without causing the aforementioned disadvantages. This is advantageous in securing a wide space between the delivering portion and the partition wall.

The delivering portion may project opposite in the vehicle width direction to a passage portion of the exhaust purifier positioned upstream from the purification unit, and the passage portion and the delivering portion may be both configured to guide gas from one side toward the other side in the vehicle width direction.

According to this configuration, the gas can be guided more smoothly from the passage portion to the delivering portion, as compared to the configuration in which the delivering portion and the passage portion are both disposed on the right side. This can reduce the deterioration of the flow path resistance as much as possible, while keeping the delivering portion and the partition wall apart from each other.

Further, the exhaust purifier may be connected to a cylinder head via an exhaust manifold. The exhaust manifold may include branch passages, each of which is connected to an associated one of cylinders through an exhaust port of the cylinder head, and a meeting portion at which the branch passages meet together to be connected to the exhaust purifier. The meeting portion may be located on one side in a cylinder bank direction of the branch passages, and extends downward on the one side. The exhaust purifier may be positioned on the other side in the cylinder bank direction relative to a lower end portion of the meeting portion.

According to this configuration, the exhaust purifier positioned toward the other side in the cylinder bank direction can ensure a space on the one side in the cylinder bank direction. This is advantageous in keeping the exhaust purifier apart from the vehicle structure including the partition wall.

Advantages of the Invention

As can be seen, according to the motor vehicle on which a vehicle engine is mounted described above, the EGR passage and the vehicle structure can be positioned apart from each other.

DESCRIPTION OF EMBODIMENTS

Embodiments of a motor vehicle on which a vehicle engine is mounted will be described in detail with reference to the drawings. The following description is only an example.FIG. 1is a diagram showing a front portion of a motor vehicle (vehicle)100on which a power train unit P to which a vehicle exhaust system disclosed herein is applied is mounted.FIG. 2is a diagram showing the power train unit P as viewed from behind, andFIG. 3is a vertical cross-sectional view showing the configuration of an exhaust passage50.

(Schematic Configuration of Power Train Unit)

First, a schematic configuration of the power train unit P will be described.

The power train unit P includes an engine1, and a transmission2connected to the engine1. The engine1is a four-stroke gasoline engine, and is configured to be able to execute both of spark ignition combustion and compression ignition combustion. The transmission2is configured as a manual transmission, for example, and transmits the output of the engine1to drive a drive shaft3to rotate.

The motor vehicle100, on which the power train unit P is mounted, is configured as a front-engine, front-drive four-wheel vehicle. That is, the power train unit P, the drive shaft3, and driving wheels (i.e., front wheels) connected to the drive shaft3are positioned in a front portion of the motor vehicle100. The motor vehicle100is configured as a so-called right-hand drive vehicle, and is provided with a driver's seat on the right side in a vehicle width direction.

A vehicle body of the motor vehicle100includes a plurality of frames. In particular, a front vehicle body includes a pair of right and left side frames101provided on both sides in the vehicle width direction and extending in a longitudinal direction of the motor vehicle100, and a front frame102disposed between the front ends of the pair of side frames101.

An engine compartment R is defined in the front portion of the vehicle body, in which the power train unit P is mounted. The engine compartment R includes, a bonnet (not shown) positioned above the power train unit P, and is configured to extend upward as it goes rearward from the front, and a dash panel103positioned behind the engine1as shown inFIG. 1to separate the engine compartment R from a cabin accommodating the passengers. The dash panel103is an example of a “partition wall” because it is positioned behind the engine1, and defines a rear portion of the engine compartment R. The partition wall is not limited to the dash panel103, and may be made of at least one of a plurality of members, such as a cowl (not shown) positioned above the dash panel103and a floor panel (not shown).

As shown inFIG. 1, a tunnel portion T is formed at a center portion of the dash panel103in the vehicle width direction to extend rearward from the dash panel103in the longitudinal direction of the vehicle. A duct for guiding exhaust gas to a muffler may be positioned in the tunnel portion T, or wind blowing out from the engine compartment R when the vehicle is traveling is caused to flow through the tunnel portion T.

Specifically, the tunnel portion T is formed by a ceiling surface103awhich extends in the longitudinal direction of the vehicle and projects upward. More specifically, as shown inFIG. 11, the ceiling surface103ahas a substantially trapezoidal cross section increasing in width from the top to the bottom and having an open bottom, and extends in the longitudinal direction of the vehicle. Although not shown in detail, a floor panel constituting the cabin together with the dash panel103also has a tunnel portion T which is formed by a ceiling surface having a similar shape, and is connected to the tunnel portion of the dash panel103.

As shown inFIG. 1andFIGS. 11 to 13, portions of the ceiling surface103a, which respectively form lower corner portions of the substantially trapezoidal shape, constitute inclined portions103beach of which is inclined downward toward the rear side in the longitudinal direction of the vehicle as it goes downward from the top as shown inFIG. 12. As can be seen fromFIG. 13, when viewed from below, each inclined portion103bforms an inclined surface which is tilted inward (inward in the vehicle width direction) as it goes rearward.

As described above, the motor vehicle100is configured as a right-hand drive vehicle. Therefore, a brake unit B to be operated by the driver is provided in front of a right portion of the dash panel103.

The engine1includes four cylinders11positioned in line and is configured as a so-called in-line four-cylinder transverse engine including four cylinders11positioned along the vehicle width direction. In this embodiment, a longitudinal direction of the engine, along which the four cylinders11are positioned (cylinder bank direction), substantially agrees with the vehicle width direction, while an engine width direction substantially agrees with the longitudinal direction of the vehicle.

In an in-line multi-cylinder engine, the cylinder bank direction coincides with the direction of a center axis of a crankshaft16serving as an engine output shaft (engine output shaft direction). In the following description, all of these directions are referred to as a “cylinder bank direction” (or a vehicle width direction).

Hereinafter, unless otherwise noted, the term “front” means one side in the engine width direction (the front in the longitudinal direction of the vehicle), and the term “rear” means the other side in the engine width direction (the rear in the longitudinal direction of the vehicle). The term “left” means one side in the longitudinal direction of the engine (the cylinder bank direction), i.e., the left in the vehicle width direction, the rear side of the engine, and toward the transmission2of the power train unit P, and the term “right” means the other side in the longitudinal direction of the engine (the cylinder bank direction), i.e., the right in the vehicle width direction, the front side of the engine, and toward the engine1of the power train unit P.

In the following description, the term “upper,” “top,” or “above” means the upper side in the vehicle height direction when the power train unit P is mounted on the motor vehicle100(hereinafter also referred to as an “in-vehicle mounted state), and the term “lower,” “bottom,” or “below” means the lower side in the vehicle height direction in the in-vehicle mounted state.

The transmission2is attached to a left side surface of the engine1, and is adjacent to the engine1in the cylinder bank direction. As shown inFIG. 2, the transmission2has a smaller dimension in the height direction than the engine1.

An engine cover4covering the engine1is provided above the engine1(specifically, above a cylinder head14). As shown inFIG. 3, a rear end portion of the engine cover4is directed obliquely downward toward the rear side, so that wind flowing along a lower surface of the rear end portion when the vehicle is traveling is guided to the exhaust passage50(specifically, to an exhaust manifold60).

(Schematic Configuration of Engine)

Next, a schematic configuration of the engine1constituting the power train unit P will be described.

In this exemplary configuration, the engine1is a front-intake rear-exhaust engine. Specifically, the engine1includes: an engine body10having the four cylinders11; an intake passage30provided to the front of the engine body10and communicating with the cylinders11via intake ports18; and an exhaust passage50provided to the rear of the engine body10and communicating with the cylinders11via exhaust ports19.

The intake passage30passes the gas (fresh air) introduced from the outside and supplies the gas to each cylinder11of the engine body10. In this exemplary configuration, the intake passage30constitutes an intake system in which a plurality of passages for guiding the gas and a device such as a supercharger or an intercooler are combined together in the front portion of the engine body10.

The engine body10combusts an air-fuel mixture of gas and fuel supplied from the intake passage30in the cylinders11. Specifically, the engine body10includes, from the bottom to the top, an oil pan12, a cylinder block13attached above the oil pan12, and a cylinder head14placed above the cylinder block13. Power generated by combusting the air-fuel mixture is delivered to the outside through the crankshaft16provided in the cylinder block13.

The four cylinders11are provided inside the cylinder block13. The four cylinders11are positioned in line along the central axis of the crankshaft16(along the cylinder bank). Each of the four cylinders11is formed like a tube. The central axes of the cylinders11(hereinafter referred to as “cylinder axes”) extend parallel to each other, and perpendicularly to the cylinder bank direction. The four cylinders11shown inFIG. 1may be hereinafter referred to as a first cylinder11A, a second cylinder11B, a third cylinder11C, and a fourth cylinder11D in this order from the right along the cylinder bank.

The cylinder head14has two intake ports18provided for each cylinder11(only those for the first cylinder11A is shown). The two intake ports18are adjacent to each other along the cylinder bank and communicate with the cylinder11.

The cylinder head14also has two exhaust ports19provided for each cylinder11. The two exhaust ports19communicate with the cylinder11.

The exhaust passage50is a passage through which exhaust gas produced through combustion of the air-fuel mixture is discharged from the engine body10. Specifically, the exhaust passage50is positioned behind the engine body10, and communicates with the exhaust ports19of the cylinders11. The exhaust passage50is provided with an exhaust manifold60and an exhaust purification system70positioned in this order from the upstream side in the flow direction of the exhaust gas. The exhaust purification system70houses therein a gasoline particulate filter (GPF) device73which functions as a gasoline particulate filter for purifying the exhaust gas. Note that the exhaust purification system70is an example of an “exhaust purifier,” and the GPF device73is an example of a “purification unit.”

In this exemplary configuration, the exhaust passage50constitutes an exhaust system in which a plurality of passages for guiding the gas such as the exhaust manifold60is combined with a device such as the exhaust purification system70.

Referring back toFIG. 1, the intake passage30and the exhaust passage50are respectively connected to a front surface and rear surface (an outer surface14adescribed later) of the engine body10. An EGR passage52which connects the intake passage30and the exhaust passage50together to constitute an external EGR system is connected to the outside (the left side in the drawing) of the engine body10. The EGR passage52allows part of the burned gas to flow back to the intake passage30. An upstream end of the EGR passage52is connected to a portion (delivering portion71cto be described later) of the exhaust purification system70located downstream of the GPF device73. A downstream end of the EGR passage52is connected to a portion of the intake passage30downstream of a throttle valve (not shown).

The EGR passage52is provided with a water-cooled EGR cooler53. The EGR cooler53cools the burned gas. The EGR cooler53receives heat only by an amount of heat used to cool the external EGR gas. Therefore, the EGR cooler53that received the heat can be used as a heat source.

Next, the configuration of the exhaust passage50of the engine1will be described in detail.

FIG. 4is a perspective view illustrating an overall configuration of the exhaust passage50.FIG. 5illustrates the exhaust passage50as viewed from behind, andFIG. 6illustrates the exhaust passage50as viewed from above.FIG. 7illustrates the exhaust purification system70as viewed from above, andFIG. 8is a cross-sectional view illustrating an internal structure of the exhaust purification system70.FIGS. 11 and 12are diagrams illustrating a relative positional relationship between the exhaust purification system70and the dash panel103as viewed from behind, and the left, respectively.FIG. 13is a diagram illustrating the relative positional relationship between the exhaust purification system and the tunnel portion T as viewed from below.

Each of the components of the exhaust passage50is connected to the engine body10, in particular, to a rear outer surface14aof the cylinder head14. As described above, the exhaust passage50is comprised of a combination of the exhaust manifold60and the exhaust purification system70. In particular, the exhaust purification system70is connected to the cylinder head14via the exhaust manifold60.

First, the configuration of the exhaust manifold60will be described.

The exhaust manifold60is positioned below an upper end portion of the cylinder head14as shown inFIG. 5, and is configured as a duct having branch passages61each of which is connected to an associated one of the cylinders11via the exhaust ports19of the cylinder head14, and a meeting portion62at which the branch passages61meet together to be connected to the exhaust purification system70as shown inFIG. 6.

The branch passages61are substantially in the shape of W when viewed from the rear side. Specifically, when the branch passages61are divided into three portions along the cylinder bank, a portion curved to bulge downward (see section I1), a portion curved to bulge upward (see section I2), and a portion curved to bulge downward again (see section I3) are positioned in this order from the left end to the right end (seeFIG. 6).

The branch passages61include a first branch passage61A connected to the first cylinder11A, a second branch passage61B connected to the second cylinder11B, a third branch passage61C connected to the third cylinder11C, and a fourth branch passage61D connected to the fourth cylinder11D.

As shown inFIG. 7, the first branch passage61A extends substantially rearward from the outer surface14aof the cylinder head14when viewed from above. When viewed from above, the second to fourth branch passages61B to61D extend obliquely rearward to the right from the outer surface14aof the cylinder head14, and merge with the first branch passage61A.

The meeting portion62is located on one side in the cylinder bank direction of the branch passages61(specifically, near the first cylinder11A and on the right in the vehicle width direction), and extends downward on this side.

Specifically, the meeting portion62is positioned at substantially the same position as the first cylinder11A in the cylinder bank direction, and extends downward from a downstream end (rear end) of the first branch passage61A. That is, an upstream end (upper end) of the meeting portion62is connected to the downstream end of the branch passage61. In contrast, a downstream end (lower end) of the meeting portion62is open to the left, to which the upstream end of a casing71constituting the exhaust purification system70is connected.

Next, the configuration of the exhaust purification system70will be described.

From the viewpoint of the relative positional relationship with the power train unit P, or the vehicle body of the motor vehicle100, the exhaust purification system70is positioned immediately behind the cylinder block13, located at approximately the center of the engine1in the vertical direction, and slightly shifted to the left in the vehicle width direction (or to the right relative to the entire power train unit P including the transmission2). As indicated by region R shown inFIG. 11, the exhaust purification system70is positioned to overlap with the tunnel portion T of the dash panel103when viewed from the rear side of the vehicle.

As shown inFIGS. 3, 12, and 13, the exhaust purification system70is located in front of the dash panel103constituting the engine compartment R in the longitudinal direction of the vehicle, and is supported to extend toward the tunnel portion T of the dash panel103.

From the viewpoint of the relative positional relationship with the exhaust manifold60, the exhaust purification system70is located below the branch passage61, and is positioned on the other side in the cylinder bank direction (specifically, near the fourth cylinder11D and on the left side in the vehicle width direction) of the lower end portion of the meeting portion62.

Further, as shown inFIG. 12, in the vehicle height direction, the exhaust purification system70is located at the upper end of the inclined portion103b(specifically, a corner portion of the dash panel103bent toward the rear side). Although not shown in the drawings, the exhaust purification system70is positioned at substantially the same level as the brake unit B described above.

Specifically, the exhaust purification system70includes a substantially L-shaped casing71, and a catalyst converter72and a GPF device73housed in the casing71.

As shown inFIG. 7, the casing71is a pipe substantially in the shape of L positioned with its horizontal bar extending in the vehicle width direction and a vertical stem extending from the bar toward the rear side of the motor vehicle100(in particular, an L-shape inverted in the longitudinal direction of the vehicle).

A portion of the casing71corresponding to the horizontal bar of the letter L (hereinafter referred to as a “bar portion” denoted by reference character “71a”) has a right end that opens toward the right. The right end serves as an upstream end of the casing71, and by extension, of the entire exhaust purification system70, and is directly connected to the downstream end of the meeting portion62as described above. The bar portion71a, including the right end serving as the upstream end of the casing71, is positioned immediately below the exhaust manifold60(specifically, the branch passage61). On the other hand, a left end of the bar portion71ais connected to a front end of a portion of the casing71corresponding to the vertical stem of the letter L (hereinafter referred to as a “stem portion” denoted by reference character “71b”).

As can be seen fromFIGS. 5 to 8, when the bar portion71ais divided into two sections aligned in the cylinder bank direction, a downstream one of the sections on the left (section I4) is vertically aligned with the portion of the branch passage61curved to bulge downward (section I1).

An upstream one of the two sections of the bar portion71aon the right (section I5) is vertically aligned with the portion of the branch passage61curved to bulge upward (section I2).

As shown inFIGS. 5, 7, and 8, the stem portion71bof the casing71projects toward the rear side of the motor vehicle100(in particular, toward the tunnel portion T of the dash panel103). A rear end of the stem portion71bserves as a downstream end of the casing71, and by extension, of the entire exhaust purification system70, and is positioned behind the exhaust manifold60, and opens rearward. An upstream end of an exhaust duct59is connected to the opening. The exhaust duct59is drawn out of the engine compartment R via the tunnel portion T described above, and is connected to a muffler (not shown) at the rear portion of the motor vehicle100.

The EGR passage52is connected to the casing71. In particular, an upstream end portion52cof the EGR passage52disclosed herein is connected to a lower portion of the exhaust purification system70in the vertical direction of the vehicle. Specifically, as shown inFIGS. 11 to 13, the upstream end portion52cis connected to a lower one of halves (see the chain line H inFIGS. 11 and 12) of the exhaust purification system70(specifically, the casing71) obtained by dividing the system70in the vehicle width direction, and to a left one of halves of the casing71obtained by dividing the casing71in the vertical direction of the vehicle.

More specifically, as shown inFIG. 12, the upstream end portion52cof the EGR passage52is connected to the rear end of the lower portion of the exhaust purification system70, and is positioned below the upper end of the inclined portion103bin the vehicle height direction. Therefore, the upstream end portion52cof the EGR passage52is positioned in front of the inclined portion103b.

As described above, the exhaust purification system70is positioned to overlap with the tunnel portion T of the dash panel103when viewed from the rear side of the vehicle. In this arrangement, the upstream end portion52cof the EGR passage52also overlaps with the tunnel portion T.

Specifically, in a lower half (and a left half thereof) of the stem portion71blocated downstream of the GPF device73, a delivering portion71cis provided to deliver the burned gas out of the casing71, and the upstream end portion52cof the EGR passage52is connected to the delivering portion71c.

The delivering portion71cis configured to deliver the gas through the opening cut through the bottom of the rear left end of the stem portion71b, and projects in a direction away from the dash panel103.

Specifically, the delivering portion71caccording to this exemplary configuration projects outward (specifically, to the left) in the vehicle width direction. A left end of the delivering portion71copens toward the front, and the upstream end portion52cof the EGR passage52is connected to the opening. Thus, the upstream end portion52cconnected to the delivering portion71cextends substantially forward as shown inFIG. 7, for example.

Further, as shown inFIG. 8, the delivering portion71cprojects from the side opposite in the vehicle width direction to a portion (passage portion) of the bar portion71acorresponding to the section I5. Taking the arrangement of the passage portion and the delivering portion71csandwiching the GPF device73in the longitudinal direction of the vehicle into account, the passage portion and the delivering portion71care positioned to face each other in the cross section shown inFIG. 8. The passage portion and the delivering portion71care both configured to guide the gas from the right side to left side in the vehicle width direction.

As shown inFIG. 13, the casing71of the exhaust purification system70is offset to the right in the vehicle width direction with respect to the tunnel portion T. Therefore, the delivering portion71cand the upstream end portion52cconnected to the delivering portion71care also offset to the right. Both of the delivering portion71cand the upstream end portion52care positioned in the left half of the casing71, but are spaced apart from the left side surface of the ceiling surface103aby the amount of the offset toward the right as can be seen fromFIG. 13.

Since the motor vehicle100is a right-hand drive vehicle as described above, the brake unit B is positioned on the right portion of the dash panel103. Therefore, as schematically shown inFIG. 1, the upstream end portion52cof the EGR passage52is positioned opposite to (i.e., on the left of) the brake unit B with the casing71interposed therebetween.

As shown inFIG. 8, the catalyst converter72is a two-bed catalyst converter having two catalysts, namely, first and second honeycomb catalysts72aand72b, positioned in series in a catalyst container. The first honeycomb catalyst72aincludes a honeycomb carrier supporting a first catalyst thereon. The second honeycomb catalyst72bincludes a honeycomb carrier supporting a second catalyst thereon.

The first catalyst is active in an oxidation reaction of unsaturated high hydrocarbon (HC), such as toluene, at a low temperature compared to the second catalyst. The second catalyst is active in an oxidation reaction of saturated low hydrocarbon (HC), such as isopentane, at a low temperature compared to the first catalyst.

The two honeycomb catalysts72aand72b, each of which is substantially formed in a short tube, are housed in an upstream portion (see section I5), which is a right portion, of the bar portion71aof the casing71. Accordingly, the two honeycomb catalysts72aand72bare vertically aligned with the portion of the branch passage61curved to bulge upward (see section I2). The portion of the branch passage61corresponding to the section I2is spaced apart upward from the two honeycomb catalysts72aand72bby the height of the upward bulge (see also distances A and B inFIG. 5).

A downstream portion (see section I4), which is a left portion, of the bar portion71ais a hollow portion. Therefore, the hollow portion is vertically aligned with the portion of the branch passage61curved to bulge downward (see section I1). The portion of the branch passage61corresponding to the section I1approaches the hollow portion below it by the height of the downward bulge.

A downstream portion (see section I4), which is a left portion, of the bar portion71ais a hollow portion. Therefore, the hollow portion is vertically aligned with the portion of the branch passage61curved to bulge downward (see section I1). The portion of the branch passage61corresponding to the section I1approaches the hollow portion below it by the height of the downward bulge.

The GPF device73includes a catalyst-carrying filter73ahoused in a filter container. The catalyst-carrying filter73aincludes a ceramic filter body made of an inorganic porous material, and the second catalyst supported thereon. Although not shown in the drawings, the catalyst-carrying filter73ahas a honeycomb structure, and includes a large number of cells extending parallel to each other.

The GPF device73is formed in a substantially tubular shape, and is housed in the stem portion71bof the casing71. In view of the relative positional relationship between the stem portion71band the exhaust manifold60, the GPF device73is positioned behind the branch passage61and the meeting portion62.

(Configuration of External EGR System)

FIG. 9illustrates an external EGR system as viewed from the left, andFIG. 10illustrates the external EGR system as viewed from above. InFIGS. 9 and 10, the transmission2is not shown.

As illustrated inFIG. 9, the EGR passage52branches off from the exhaust passage50with the catalyst purification system70disposed therein, and has a downstream end portion connected to the intake passage30.

As described above, the EGR cooler53is disposed in the EGR passage52to cool the gas passing through the EGR passage52. Hereinafter, of the EGR passage52, a portion connecting the exhaust passage50and the EGR cooler53will be referred to as an upstream EGR passage52a, and a portion connecting the EGR cooler53and the intake passage30will be referred to as a downstream EGR passage52b. An upstream end of the upstream EGR passage52ais the upstream end portion52cdescribed above.

Specifically, as illustrated inFIGS. 9 and 10, the upstream EGR passage52aextends obliquely upward and forward along the left part of the casing71, and then turns left not to interfere with the left part of the engine body10. Then, the upstream EGR passage52aextends obliquely upward and forward again to reach the EGR cooler53. The upstream end of the upstream EGR passage52ais connected to the delivering portion71cof the casing71in the exhaust purification system70, and the downstream end (front end) of the upstream EGR passage52ais connected to the upstream end (rear end) of the EGR cooler53, as described above.

The EGR cooler53is shaped into a square tube slightly angled with respect to the longitudinal direction. At least when the engine is mounted on the vehicle, the EGR cooler53is positioned so that its openings at both ends are obliquely oriented toward the front and rear sides in the longitudinal direction at substantially the same location of the exhaust manifold60in the vertical direction (i.e., above the exhaust purification system70). The upstream end of the EGR cooler53is directed obliquely downward and rearward, and is connected to the downstream end of the upstream EGR passage52aas described above. Meanwhile, the downstream end (front end) of the EGR cooler53is directed obliquely upward and forward, and is connected to the upstream end (rear end) of the downstream EGR passage52b.

The downstream EGR passage52bextends upward as it goes from the upstream to the downstream along the flow direction of the gas. Specifically, as illustrated inFIGS. 9 and 10, the downstream EGR passage52bextends obliquely upward and forward along the left part of the engine body10, and turns substantially forward. The upstream end (rear end) of the downstream EGR passage52bis connected to the downstream end of the EGR cooler53as described above. On the other hand, the downstream end (front end) of the downstream EGR passage52bis connected to a rear portion of the intake passage30.

(Configuration Related to Collision of Motor Vehicle)

As shown inFIG. 1, when the engine1is mounted on the front portion of the vehicle body, at least part of the exhaust passage50is located at a rear portion of the engine compartment R. In this case, if the engine is a rear exhaust engine, in particular, the GPF device73connected to the exhaust passage50is also located at the rear portion of the engine compartment R.

On the other hand, as described above, the EGR passage52branches off from the exhaust passage50downstream of the GPF device73. Thus, the upstream end portion52cof the EGR passage52becomes close to the rear end of the engine compartment R because the GPF device73is located at the rear portion of the engine compartment as shown inFIG. 8and other drawings. Therefore, the upstream end portion52cbecomes close to a vehicle structure including the dash panel103(in particular, the tunnel portion T of the dash panel).

According to another possible configuration, the GPF device73may be inserted into the tunnel portion T of the dash panel103, together with the delivering portion71c. However, when such a configuration is adopted, the dimension of a passage from the engine1to the GPF device73is elongated in the longitudinal direction of the vehicle, which is not preferable in terms of the downsizing of the engine1.

In recent years, when an elaboration is made to the configuration of the engine to downsize the engine, for example, the EGR passage52is required to be positioned as far as possible from the vehicle structure.

In contrast, as shown inFIGS. 12 and 13, the exhaust purification system70which houses the GPF device73is positioned in front of the tunnel portion T to extend toward the tunnel portion T, without being inserted into the tunnel portion T. This can shorten the dimension in the longitudinal direction of the vehicle, and by extension, can downsize the engine1.

As shown inFIG. 11, the tunnel portion T is generally formed by the ceiling surface103athat projects upward. Thus, as shown inFIG. 12, connecting the EGR passage52to the lower half of the casing71of the exhaust purification system70can make the upstream end portion52cfurther apart from the ceiling surface103aas compared to the case where the EGR passage52is connected to the upper half of the casing71, for example. This can block the upstream end portion52cof the EGR passage52from approaching the ceiling surface103aof the tunnel portion T.

In this way, the engine1can be downsized, and the EGR passage52and the vehicle structure can be positioned apart from each other.

Further, as shown inFIG. 12, when viewed from the side of the vehicle, the upstream end portion52cof the EGR passage52is disposed below the upper end of the inclined portion103b. Thus, the upstream end portion52cof the EGR passage52is positioned in front of the inclined portion103b. Taking the rearward inclination of the inclined portion103binto account, the upstream end portion52cof the EGR passage52can be positioned apart from the dash panel103in accordance with the inclination angle.

As shown inFIG. 11, the upstream end portion52cof the EGR passage52is positioned to overlap with the tunnel portion T when viewed from the rear side of the vehicle. In this arrangement, if the engine1is moved immediately behind upon collision of the vehicle, for example, the upstream end portion52cof the EGR passage52goes back to fit in the tunnel portion T.

Further, as shown inFIG. 13, projecting the delivering portion71cin the direction away from the dash panel103advantageously allows the delivering portion71cto be positioned apart from the dash panel103, and by extension, from the inner wall surface of the tunnel portion T.

Moreover, as shown inFIG. 13, the delivering portion71cis configured to project toward the left in the vehicle width direction. Here, for example, if the delivering portion71cprojects upward in the vehicle height direction, the delivering portion71cbecomes close to the ceiling surface103adescribed above, i.e., projects in a direction toward the dash panel103, which is disadvantageous.

On the other hand, if the delivering portion71cprojects downward in the vehicle height direction, the delivering portion71cis spaced apart from the dash panel103, and also from the ceiling surface103a. In this case, however, moisture contained in the burned gas is accumulated at the lower end of the delivering portion71c. This configuration is also disadvantageous because the moisture contains components that cause corrosion of metals, such as sulfuric acid.

The delivering portion71ccan be configured to project rearward in the longitudinal direction of the vehicle. However, this configuration may bring the delivering portion71ccloser to the dash panel103. In addition, the distance between the delivering portion71cand the EGR passage52increases in the longitudinal direction of the vehicle, which is disadvantageous also from the viewpoint of downsizing of the engine1.

In another configuration, the delivering portion71ccan be configured to project forward in the longitudinal direction of the vehicle. However, this configuration may increase the curvature of a passage from the casing71to the delivering portion71c, depending on the shape of the casing71in which the GPF device73is housed. This may be disadvantageous from the viewpoint of reduction of a flow path resistance.

Therefore, as shown inFIG. 13, projecting the delivering portion71ctoward the left in the vehicle width direction can block the delivering portion71cfrom approaching the dash panel103without causing the aforementioned disadvantages.

Further, if the delivering portion71cprojects to the left, the delivering portion71cis positioned opposite to (i.e., on the left of) the brake unit B with the casing71interposed therebetween as shown inFIG. 1.

Further, as shown inFIG. 8, the delivering portion71cand a portion (passage section) of the bar portion71acorresponding to the section I5are positioned to face each other in the cross section shown inFIG. 8. In this arrangement, the gas can be guided more smoothly from the passage portion to the delivering portion71c, as compared to the configuration in which the delivering portion71cand the passage portion are both disposed on the right side. This can reduce the deterioration of the flow path resistance as much as possible, while keeping the delivering portion71cand the dash panel103apart from each other.

Moreover, as shown inFIG. 13, the exhaust purification system70positioned to the right in the vehicle width direction can ensure a space on the left side of the exhaust purification system70. This is advantageous in blocking the exhaust purification system70from approaching the vehicle structure including the dash panel103.

Other Embodiments

In the foregoing embodiment, an in-line four-cylinder engine has been described as an example, but the present disclosure is not limited thereto. For example, the engine may be an in-line six-cylinder engine. In addition, the form of the exhaust manifold60may be appropriately changed depending on the number of cylinders.

In the foregoing embodiment, the transverse engine1has been described as an example, but the present disclosure is not limited thereto. For example, the engine may be a longitudinal engine. If the longitudinal engine is adopted, the exhaust manifold is positioned on either the left or right side of the engine, but the exhaust purification system70is positioned behind the engine similarly to the case where the transverse engine1is used. Therefore, the longitudinal engine also has the same advantages as the transverse engine.

In the foregoing embodiment, the upstream end portion52cof the EGR passage52is positioned to overlap with the tunnel portion T when viewed from the rear side of the vehicle. However, the upstream end portion52cmay be positioned to overlap with the tunnel portion T when viewed from the front side of the vehicle. Even in this arrangement, the above-described advantages can be obtained.

DESCRIPTION OF REFERENCE CHARACTERS