JP5045207B2 - Vehicle front structure - Google Patents

Description

  The present invention relates to a front structure of a vehicle, and in particular, a front portion of a vehicle in which an engine is disposed horizontally in an engine room at the front of the vehicle, an intake pipe is disposed in front of the engine, and an exhaust pipe is disposed behind the engine. Concerning structure.

  Conventionally, in general vehicles, a front engine / front drive system (hereinafter referred to as FF system) is often employed in order to secure as much cabin space as possible. At this time, since the engine output shaft and the drive shaft are positioned in parallel in terms of driving efficiency, the engine is normally disposed horizontally (a position where the cylinder row faces in the vehicle width direction).

  In recent years, in order to reduce exhaust gas emissions, many vehicles adopt a rear exhaust layout in which an exhaust pipe is arranged on the rear side of the engine to shorten the distance from the exhaust port to the catalyst. Yes.

  For example, Patent Document 1 below discloses a vehicle that employs a rear exhaust layout in which an exhaust pipe is disposed behind an engine in an FF vehicle that is installed horizontally on the engine.

JP-A-11-198663

  By the way, in order to increase the exhaust efficiency of the engine and increase the engine output, it is desirable to lay out the exhaust pipe so as to extend as straight as possible.

  However, the exhaust pipe of the vehicle described in Patent Document 1 described above has a dash panel located rearward, so that it bends downward from the upper part of the engine in the vertical direction, and at the lower end thereof in the horizontal direction on the rear side. It is laid out in a substantially crank shape so as to be bent.

Therefore, in the engine of a vehicle described in Patent Document 1, the exhaust pipe complicatedly bent, it is impossible to increase the exhaust efficiency, it is impossible to increase the engine output to the charge amount.

  Further, if the exhaust pipe is laid out behind the engine, the exhaust pipe presses the dash panel due to the retreat of the engine at the time of a vehicle collision, and there is a possibility that deformation of the dash panel toward the rear side is increased.

  As a method for solving such a problem, a tunnel enlarged portion having a large internal space is formed at the center position in the vehicle width direction of the dash panel, and the exhaust pipe is extended so as to extend obliquely downward on the vehicle rear side substantially linearly in the tunnel enlarged portion. Can be laid out.

  However, if the tunnel enlargement portion is too large, the front space of the passenger compartment is affected, and there is a problem that the passenger compartment space is narrowed.

  In particular, in order to eliminate exhaust interference between the cylinders, when a plurality of exhaust pipes extending from each cylinder are once assembled into two and then assembled into one, the two exhaust pipes are Since it is necessary to lay out in the tunnel enlargement part, it may be particularly large.

Here, if two exhaust pipes are arranged side by side in the vertical direction, the two exhaust pipes are offset in the vertical direction in relation to the cylinder rows arranged in the vehicle width direction. substantially linear effort to increase the exhaust efficiency by arranging the as-mentioned effects shake not obtained to the charge amount of problems.

  Therefore, the present invention provides a vehicle front structure in which an engine is disposed horizontally in an engine room at the front of the vehicle, an intake pipe is disposed in front of the engine, and an exhaust pipe is disposed behind the engine. An object of the present invention is to provide a vehicle front structure capable of increasing the exhaust efficiency of the exhaust pipe as much as possible and increasing the engine output while arranging the book in the tunnel portion.

The vehicle front structure according to the present invention is a vehicle in which an engine is disposed horizontally in an engine room at the front of the vehicle, an intake pipe is disposed in front of the engine, and an exhaust pipe is disposed behind the engine. A tunnel structure that is a front structure and that protrudes toward the vehicle interior side and extends in the vehicle front-rear direction is provided at the center in the vehicle width direction of the connecting portion between the dash panel and the floor panel constituting the front wall of the vehicle interior. A tunnel enlarged portion that protrudes greatly toward the vehicle interior side is formed at a front portion of the engine, and the exhaust pipe includes a plurality of independent exhaust pipes connected to each cylinder of the engine, and a downstream side of the independent exhaust pipe. A collective exhaust pipe that collects two independent exhaust pipes, and the two collective exhaust pipes are arranged in parallel in the vehicle width direction at a position corresponding to the tunnel enlarged portion, and the rear of the vehicle in the tunnel enlarged portion An upper wall surface that is inclined downward on the side is provided. An exhaust port of the engine is set at a position below the inclined extension line, the exhaust pipe is formed so as to extend downward from the exhaust port on the upper side of the vehicle to the vehicle rear side, and further a catalyst that constitutes a part of the collective exhaust pipe Is disposed at a position corresponding to the tunnel enlarged portion, and a flexible tube is disposed behind the catalyst .

According to the above configuration, the two collective exhaust pipes are arranged in parallel in the vehicle width direction at a position corresponding to the tunnel enlarged portion, so that the two collective exhaust pipes can be laterally offset without being vertically offset. It can be laid out in a substantially straight line shape.
For this reason, since the two collective exhaust pipes can be arranged substantially linearly in a side view, the exhaust efficiency of the engine can be increased.

In addition, since the catalyst constituting a part of the collective exhaust pipe is arranged at a position corresponding to the tunnel enlarged portion, a catalyst with a large occupied space can be laid out using the space in the tunnel enlarged portion. Will do.
Therefore, it is not necessary to install a catalyst with a large occupied space between the engine and the dash panel, and collision safety can be improved.
Moreover, since the air (hot air) around the catalyst to be heated can be discharged to the vehicle rear side using the tunnel portion extending in the front-rear direction, heat damage around the catalyst can be prevented.

In one embodiment of the present invention, a propeller shaft that transmits the driving force of the engine to the rear wheels is provided, and the propeller shaft is disposed below the two collective exhaust pipes.
According to the above configuration, by arranging the propeller shaft below the collective exhaust pipe, the propeller shaft is not obstructed, and the collective exhaust pipe can be arranged by effectively using the space above the propeller shaft. it can.
For this reason, the two collective exhaust pipes can be arranged substantially linearly without being restricted by the propeller shaft.
Therefore, even in a four-wheel drive vehicle having a propeller shaft, the exhaust efficiency of the engine can be increased.

In one embodiment of the present invention, a collecting portion for collecting the exhaust pipes is provided behind the two collecting exhaust pipes, and the collecting portion is disposed on the side of the propeller shaft.
According to the above configuration, by arranging the collecting portion that collects the exhaust pipes in one side to the side of the propeller shaft, the space occupied by the exhaust pipe is reduced, and the propeller shaft is avoided and the vehicle rear side It can arrange | position so that it may extend diagonally downward.
Therefore, without increasing the tunnel enlarged section in the vehicle width direction, the exhaust pipe, to avoid the propeller shaft, Ru can be laid in a substantially linear shape.

In one embodiment of the present invention, a steering mechanism for steering the front wheels is arranged on the vehicle front side of the catalyst.
According to the above configuration, since the steering mechanism is arranged on the vehicle front side of the catalyst, it is difficult for hot air around the catalyst to flow through the steering mechanism while the vehicle is traveling.
Therefore, the heat damage by the catalyst to the steering mechanism can be suppressed, and the durability of the steering mechanism can be enhanced.

In one embodiment of the present invention, the engine is inclined so that the upper part of the engine is located on the vehicle rear side.
According to the said structure, a space can be ensured in the engine upper part front and the engine lower part rear by the engine being inclined and arranged (slant arrangement) on the vehicle rear side. Further, the position of the exhaust port of the engine can be lowered.
For this reason, the arrangement space of the intake pipe arranged in front of the engine can be expanded. Further, the front differential disposed behind the engine can be disposed on the vehicle front side. Furthermore, since the position of the exhaust port is lowered, the exhaust pipe can be more easily laid out in a straight line, and the engine exhaust efficiency can be increased. In addition, since the distance to the catalyst can be shortened, early activation of the catalyst can be achieved.
Therefore, the performance of the intake / exhaust system of the rear exhaust engine can be enhanced by tilting the engine to the rear, and the amount of overhanging of the vehicle can be reduced, so that the vehicle steering performance can also be enhanced.

According to the present invention, since the two collective exhaust pipes can be arranged substantially linearly in a side view, the exhaust efficiency of the engine can be increased.
Therefore, in the front structure of a vehicle in which the engine is disposed horizontally in the engine room in the front of the vehicle, the intake pipe is disposed in front of the engine, and the exhaust pipe is disposed in the rear of the engine, the two exhaust pipes are arranged in the tunnel section. The engine output can be increased by increasing the exhaust efficiency of the exhaust pipe as much as possible.

Hereinafter, the vehicle front structure of the present embodiment will be described with reference to the drawings.
First, the overall structure of the front structure of the vehicle will be described with reference to FIGS. 1 is a perspective view showing a characteristic part of a vehicle front structure, FIG. 2 is an overall side view of the vehicle front structure, FIG. 3 is an overall front view excluding an engine, and FIG. 4 includes a body frame and the like. FIG. 5 is an overall bottom view including a vehicle body frame and the like.

  As shown in FIG. 2, the front portion of the vehicle includes an engine room ER in which the engine 7 is disposed and a vehicle room CR formed behind the engine room ER.

Engine room ER is defined by the hood 1 extending in the longitudinal direction of the vehicle the upper before falling, partitioned by the front grille 2 and the front vans path 3 located front upper and lower, further dash panel extending aft vertically It is divided into 4 parts.

  The vehicle compartment CR has an upper portion defined by a roof panel (not shown), a front portion defined by the dash panel 4 described above, a lower portion a floor panel 5 extending in the vehicle longitudinal direction, and a tunnel portion 6 extending in the vehicle longitudinal direction. It is divided and configured.

Among these, an in-line four- cylinder I-type engine 7 is disposed horizontally in the engine room ER. That is, the I-type engine 7 cylinder bank is arranged so as to extend in the vehicle width direction with four cylinders. The engine 7 is arranged to be inclined (slant) to the rear side so that the engine upper portion 7a is located slightly on the rear side. This inclination angle α is set to about 15 °.

  Further, an intake manifold 8 that introduces intake air into each cylinder is installed in front of the engine upper portion 7a, and an exhaust manifold 9 that exhausts exhaust gas from each cylinder is installed behind the engine upper portion 7a.

  The intake manifold 8 is curved so as to surround the surge tank 10 extending in the cylinder row direction, and each has a predetermined intake passage length.

  On the other hand, the exhaust manifold 9 is formed so as to extend obliquely downward on the vehicle rear side in a substantially straight line from the exhaust port 11 on the rear surface of the engine upper portion 7a inclined rearward.

Further, as shown in FIG. 4, a transmission 12 is disposed on one side of the engine 7 (the left side in FIG. 4). A front differential 13 is disposed at the rear of the transmission 12. Further, a transfer device 30 is arranged on the other side of the front differential 13 (the right side of the drawing in FIG. 4). The transfer device 30 is configured to transmit a driving force to a rear wheel (not shown) via a propeller shaft 31.
The transmission 12 is a so-called lateral type transmission 12 in which an input shaft and an output shaft (not shown) extend in the vehicle width direction, and without changing the direction of the driving force of the engine 7, a helical gear or the like (spur gear). Is transmitted to the front differential 13.

  The front differential 13 is configured to transmit the output from the transmission 12 to the left and right front wheels 14 and 14, and defines the output position of a drive shaft (not shown). The drive shaft extends in the vehicle width direction and transmits driving force to the front wheels 14 and 14 installed on both sides of the vehicle.

  The transfer device 30 is configured to transmit a driving force to the propeller shaft 31 using a direction changing gear such as a bevel gear via a transfer shaft (not shown). The propeller shaft 31 is disposed so as to extend in the vehicle front-rear direction in the tunnel portion 6 and is configured to transmit a driving force to a rear wheel (not shown). In this embodiment, the vehicle is configured as a four-wheel drive vehicle by transmitting the driving force to the front wheels 14 and 14 and the rear wheels.

  As shown in FIG. 2, a radiator 15 is installed in front of the engine room ER in front of the engine 7. A steering rack 16 of a steering mechanism for steering the front wheels 14 is installed behind the engine lower portion 7b.

As shown in FIG. 3, the dash panel 4 that constitutes the front wall of the passenger compartment is formed of a panel body that extends in the vertical direction and in the entire region in the vehicle width direction. A tunnel opening 17 connected to the tunnel portion 6 is provided in the center of the vehicle width of the dash panel 4.

As shown in FIG. 1, the floor panel 5 constituting the passenger compartment floor surface extends from the lower end of the dash panel 4 to the vehicle rear side and extends in the vehicle width direction. Further, side sills 18 and 18 which are vehicle body skeleton members extend in the vehicle front-rear direction at both side ends of the floor panel 5 (see FIG. 5).

At the center of the floor panel 5 in the vehicle width direction, as shown in FIG. 1, a tunnel portion 6 is formed that protrudes upward (in the vehicle interior) in a substantially hat shape and extends in the vehicle front-rear direction. The width W in the vehicle width direction and the height H in the vertical direction of the tunnel portion 6 are such that one exhaust pipe (rear exhaust pipe 19) and the propeller shaft 31 can be disposed inside (outside the cabin) as a whole. It is set.

At the front part of the tunnel part 6, a tunnel expansion part 20 that protrudes further upward and in the vehicle width direction is formed. The tunnel enlargement portion 20 is formed large and high in the interior (outside the passenger compartment) so that the components of the exhaust system and the propeller shaft 31 extending rearward from the exhaust manifold 9 can be laid out.

  That is, corresponding to the inclination of the exhaust manifold 9 described above, the upper wall surface 20a extending inclined from the upper part of the dash panel 4 to the rear of the vehicle, and corresponding to the plurality of exhaust manifolds 9 and inclined toward the center side toward the rear of the vehicle. The side wall surfaces 20b and 20c extending to form a tunnel expansion portion 20 with a large internal space S, and in the internal space S of the tunnel expansion portion 20, the direct catalyst 21A, 21B, the Y-shaped exhaust pipe 22 and the like The exhaust system components and the propeller shaft 31 extending in the vehicle front-rear direction are laid out.

Among these, the components of the exhaust system will be described in detail.
As shown in FIG. 4, an exhaust manifold 9 (9a, 9b, 9c, 9d) is disposed behind the engine 7. The exhaust manifold 9 is configured such that four exhaust manifolds 9a, 9b, 9c, and 9d are temporarily gathered into two to avoid exhaust interference. That is, since the combustion timing is set as the first cylinder E1, the third cylinder E3, the fourth cylinder E4, and the second cylinder E2, the exhaust manifold 9a of the first cylinder E1 and the exhaust manifold of the fourth cylinder E4 at both ends. 9d and the exhaust manifold 9b of the center second cylinder E2 and the exhaust manifold 9c of the third cylinder E3 are assembled together.

  Corresponding to the assembled exhaust manifolds 9a, 9b, 9c, 9d, two substantially cylindrical direct catalysts 21A, 21B are provided side by side in the vehicle width direction. Specifically, the first catalyst 21A is provided corresponding to the pipe in which the exhaust manifold 9a of the first cylinder E1 and the exhaust manifold 9d of the fourth cylinder E4 are assembled, and the exhaust manifold 9b of the second cylinder E2 and the three A second catalyst 21B is provided corresponding to the pipe in which the exhaust manifold 9c of the numbered cylinder E3 is assembled.

  In this way, by arranging the two direct catalysts 21A, 21B in the vehicle width direction in parallel, the exhaust from the exhaust manifolds 9a, 9b, 9c, 9d aligned in the vehicle width direction is offset in the vertical direction, respectively. There is no smooth discharge to the downstream side.

The direct catalysts 21A and 21B are constituted by a three-way catalyst, but mainly at this position in order to purify HC (hydrocarbon) and CO (carbon monoxide) during cold. It is installed.

  Behind this, a substantially Y-shaped Y-shaped exhaust pipe 22 that collects two pipe lines into one is provided. When the exhaust gas passes through the direct catalysts 21A and 21B, it is difficult to be affected by the exhaust interference. Therefore, the exhaust system is assembled at this position.

  Further, a substantially cylindrical flexible joint 23 is provided on the rear side, and the roll vibration of the engine 7 and the like are absorbed by the flexible joint 23. For this reason, the exhaust system to the flexible joint 23 swings together with the engine 7.

The rear of the flexible joint 23 is provided with a substantially cylindrical Ann Duff Tsu DOO Catalyst 24. The Ann Duff Tsu DOO Catalyst 24 also has constituted a three-way catalyst, mainly, in order to purify NOx (nitrogen oxides), placed in this position.

The rear (downstream), the rear exhaust pipe 19 of the one, the tunnel portion 6 is formed so as to extend in the vehicle rear, is provided a silencer (not shown) to the rear end, the exhaust gas in the rear of the vehicle It is configured to discharge.

  Among the components of the exhaust system configured as described above, as shown in FIG.

  As described above, this is because the exhaust manifold 9 is formed so as to extend obliquely downward from the exhaust port 11 of the engine upper portion 7a in a straight line when viewed from the side. This is because they are arranged so as to extend obliquely downward corresponding to the above arrangement.

  Thus, the exhaust efficiency of the engine 7 can be increased by arranging the exhaust systems so as to be arranged in a substantially straight line.

  Thus, by forming the large tunnel enlargement portion 20 at the front portion of the tunnel portion 6, it becomes possible to lay out the components of the exhaust system in a substantially linear shape.

The positional relationship between the components of the exhaust system and the propeller shaft 31 in the tunnel enlargement unit 20 will be described in more detail with reference to FIGS. 6 and 7. FIG. 6 is a detailed side sectional view in the vicinity of the enlarged portion of the tunnel, and FIG. 7 is a sectional view taken along line AA in FIG.

  As shown in FIG. 6, the upper wall surface 20a of the tunnel expanding portion 20 is formed so as to incline downward from the vicinity of the upper portion 4a of the dash panel 4 with a predetermined inclination angle β (for example, β = 20 °). This inclination angle β is set to a value almost the same as the inclination angle γ (for example, γ = 20 °) of the direct catalyst 21. This is to make it easier for the exhaust system to sink into the tunnel portion 6 along the upper wall surface 20a in the event of a vehicle collision, as will be described later.

  Further, the exhaust port 11 is set to be positioned below the extended line L of the inclination angle β of the upper wall surface 20a. This is to make it easier to guide the exhaust manifold 9 into the space 6A of the tunnel portion 6 when the vehicle collides, and to lay out the components of the exhaust system more linearly.

  Moreover, the direct catalystists 21A and 21B arranged in the tunnel expansion portion 20 are set so that two extend in the vehicle front-rear direction in parallel with each other in the vehicle width direction. And the propeller shaft 31 is arrange | positioned under the direct catalystists 21A and 21B.

  As shown in FIG. 7, the two direct catalysts 21A and 21B installed in the internal space S of the tunnel expansion unit 20 are composed of a first catalyst 21A and a second catalyst 21B, and are respectively in the same vertical position. They are laid out side by side.

  By laying out in this way, as described above, the first catalyst 21A and the second catalyst 21B are not offset in the vertical direction, so that all the components of the exhaust system can be laid out in a substantially linear shape in a side view. This makes it possible to increase the exhaust efficiency.

In addition, by laying out the propeller shaft 31 below the direct catalysts 21A and 21B, the layout freedom of the two direct catalysts 21A and 21B is not hindered, and the internal space S of the tunnel expanding portion 20 is not disturbed. The upper part can be effectively used as a layout space for the direct catalyst lists 21A and 21B.

  As shown in FIG. 6, one flexible joint 23 is provided behind the direct catalysts 21 </ b> A and 21 </ b> B via a Y-shaped exhaust pipe 22. The flexible joint 23 is disposed so as to be larger than the inclination of the direct catalyst 21A, 21B, and is disposed just to the side of the propeller shaft 31.

  As shown in FIG. 8, by laying out the flexible joint 23 on the side of the propeller shaft 31, the propeller shaft 31 can be avoided at a portion where the exhaust pipes are gathered into one, and the propeller shaft 31 and the exhaust system This prevents an increase in the width of the tunnel portion 6 in the intersection region.

  Next, the behavior at the time of a vehicle collision will be described with reference to FIG.

  FIG. 9 is an explanatory view showing the behavior at the time of a vehicle collision in a side view, in which (a) shows the initial stage of the collision, (b) shows the middle stage of the collision, and (c) shows the late stage of the collision.

  As shown in FIG. 9A, when a collision load F acts from the front of the vehicle, the engine 7 moves backward and the exhaust manifold 9 also moves backward. At this time, since the upper wall surface 20a of the tunnel expanding portion 20 is inclined, the direct catalyst 21 and the like come into contact with the upper wall surface 20a and the exhaust system components (9, 21, 22, 23, 24) are moved downward. Will be guided to.

At this time, since the flexible joint 23 behind the direct catalyst 21 is relatively fragile, bending occurs in this portion, and more exhaust system components (9, 21, 22, 23, 24) are expanded in the tunnel. It becomes easy to sink into the internal space S of the part 20 and the internal space 6A of the tunnel part 6.

As shown in (b) of FIG. 9, in the middle of the collision, the direct catalyst 21 is guided downward by the upper wall surface 20 a of the tunnel expanding portion 20. As a result, the upper portion 7a of the engine 7 is further rotated rearward, and the exhaust system components (9, 21, 22, 23, 24) are further connected to the internal space S of the tunnel expansion portion 20 and the tunnel portion 6. It becomes easy to dive into the internal space 6A .

As shown in FIG. 9 (c), in the later stage of the collision, almost all the exhaust system components (9, 21, 22, 23, 24) of the engine 7 sink into the tunnel expansion part 20 and the tunnel part 6. Thus, the exhaust system components (9, 21, 22, 23, 24) do not affect the dash panel 4 at all.

  Further, since the propeller shaft 31 disposed below is provided with a collision safety mechanism by a drop-off mechanism on a center bearing support (not shown), the propeller shaft 31 is dropped downward from the tunnel portion 6 as shown in the figure. However, the collision safety of the vehicle is enhanced without preventing the engine 7 from moving backward.

  In addition, the collision safety mechanism of the propeller shaft 31 may be a so-called collapse mechanism configured such that the shaft contracts when a compressive force is applied in the axial direction.

  Thus, even if the two direct catalysts 21A and 21B are arranged side by side in the vehicle width direction, the propeller shaft 31 drops downward, so that the downward movement of the two direct catalysts 21A and 21B is not hindered. The collision safety of the vehicle can be ensured.

Next, the effect of this embodiment is demonstrated.
The vehicle front structure of this embodiment is provided with a tunnel portion 6 that protrudes toward the vehicle interior side and extends in the vehicle front-rear direction at the center in the vehicle width direction between the dash panel 4 and the floor panel 5. A tunnel expansion portion 20 that protrudes greatly toward the vehicle interior side is formed at the front of the vehicle, and two direct catalystists 21A and 21B in which exhaust manifolds 9 are assembled are located at positions corresponding to the tunnel expansion portion 20 in the vehicle. They are arranged in parallel in the width direction.

As a result, the two direct catalysts 21A and 21B can be laid out in a substantially linear shape in a side view without being offset in the vertical direction.
For this reason, since the two direct catalystists 21A and 21B can be arranged substantially linearly in a side view, the exhaust efficiency of the engine 7 can be increased.

  Therefore, in the front structure of the vehicle in which the engine 7 is disposed horizontally in the engine room ER at the front of the vehicle, the intake manifold 8 is disposed in front of the engine 7, and the exhaust manifold 9 is disposed behind the engine 7. While arranging the two catalyst players 21A and 21B in the tunnel expansion portion 20, the exhaust efficiency of the exhaust system can be increased as much as possible to increase the engine output.

Moreover, in this embodiment, the propeller shaft 31 which transmits the driving force of the engine 7 to a rear wheel is provided, and this propeller shaft 31 is arrange | positioned under the two direct catalystists 21A and 21B.
Thereby, the propeller shaft 31 does not get in the way, and the direct catalyst 21A, 21B can be freely arranged by effectively using the space above the propeller shaft 31.
For this reason, the direct catalysts 21 </ b> A and 21 </ b> B can be arranged substantially linearly without being restricted by the propeller shaft 31.
Therefore, even in a four- wheel drive vehicle having the propeller shaft 31, the exhaust efficiency of the engine 7 can be increased.

Further, in this embodiment, a flexible joint 23 in which exhaust systems are gathered together is provided behind the two direct catalysts 21 </ b> A and 21 </ b> B, and the flexible joint 23 is disposed on the side of the propeller shaft 31.
Accordingly, the space occupied by the exhaust system can be reduced, and the propeller shaft 31 can be avoided and the vehicle can be arranged to extend obliquely downward on the vehicle rear side.
Therefore, the components (9, 21, 22, 23, 24) of the exhaust system are substantially straightened while avoiding the propeller shaft 31 without enlarging the tunnel portion 6 and the tunnel enlarged portion 20 in the vehicle width direction. Can be laid out.

In this embodiment, the direct catalyst lists 21A and 21B are arranged at positions corresponding to the tunnel enlargement unit 20.
Thereby, the direct catalyst list 21 with a large occupation space can be laid out by using the internal space S of the tunnel enlargement unit 20.
Therefore, it is not necessary to install the direct catalyst 21 having a large occupied space between the engine 7 and the dash panel 4, and the direct catalyst 21 does not press the dash panel 4 by the retreat of the engine 7, so that collision safety is further improved. Can increase the sex.
Further, since air (hot air) around the heated direct catalyst 21 can be discharged to the vehicle rear side using the tunnel portion 6 extending in the front-rear direction, heat damage around the catalyst can be prevented. it can.

In this embodiment, a flexible joint 23 is provided at a position behind the direct catalyst 21.
For this reason, the weakness of this flexible joint 23 can be utilized to make it easier for the components of the exhaust system to be deformed downward, and to promote the dive into the tunnel enlarged portion 20 at the time of a vehicle collision.

In this embodiment, a steering rack 16 for steering the front wheels 14 is disposed on the vehicle front side of the direct catalyst 21 (see FIGS. 2 and 5).
As a result, hot air around the direct catalyst 21 is less likely to flow through the steering rack 16 during traveling of the vehicle.
Therefore, the heat damage by the direct catalyst 21 with respect to the steering rack 16 can be suppressed, and the durability of the steering rack 16 can be enhanced.

Further, in this embodiment, the engine 7 is inclined so that the engine upper portion 7a is located on the vehicle rear side (see FIG. 2).
As a result, a space can be secured in front of the engine upper portion 7a and behind the engine lower portion 7b. Further, the position of the exhaust port 11 of the engine 7 can be lowered.
For this reason, the arrangement space of the intake manifold 8 arranged in front of the engine 7 can be expanded. Further, the front differential 13 disposed behind the engine 7 can be disposed on the vehicle front side. Furthermore, since the position of the exhaust port 11 is lowered, the exhaust system components (9, 21, 22, 23, 24) can be more easily laid out in a substantially straight line, and the exhaust efficiency of the engine 7 can be increased. In addition, since the distance to the direct catalysts 21A and 21B can be shortened, early activation of the catalyst can be achieved.
Therefore, by arranging the engine 7 to be inclined rearward, the performance of the intake / exhaust system of the rear exhaust engine can be improved, and the amount of overhang of the vehicle can be reduced, so that the vehicle's driving performance can also be improved. .

As a reference example , a vehicle front structure as shown in FIG. 10 is also conceivable. That is, two flexible joints 123A and 123B are arranged immediately after the exhaust manifold 9 (only one is shown in the drawing), and a Y-shaped exhaust pipe 122 is arranged behind the two flexible joints 123A and 123B, and behind the two flexible joints 123A and 123B. The catalyst 124 is configured to be arranged, and among these, the two flexible joints 123A and 123B are arranged side by side in the vehicle width direction in the tunnel enlarged portion 20 and laid out.

As described above, by laying out the flexible joints 123A and 123B in the tunnel expanding portion 20, the reference space also uses a relatively large space (internal space S) in the tunnel expanding portion 20 to occupy a large space. The flexible joints 123A and 123B can be easily laid out.

  Further, since the flexible joints 123A and 123B are arranged in parallel in the vehicle width direction, the components of the exhaust system can be laid out in a substantially straight line without being offset in the vertical direction, as in the above-described embodiment. Efficiency can be increased.

  Therefore, even if the two flexible joints 123A and 123B are arranged immediately after the exhaust manifold 9, the exhaust efficiency of the engine 7 can be increased and the engine output can be improved.

The configuration of the invention of this, in correspondence with the embodiment described above,
The intake pipe of the present invention corresponds to the intake manifold 8 and the surge tank 10,
Hereinafter, similarly, the exhaust pipe corresponds to the exhaust manifold 9, the direct catalyst 21A, 21B, the Y-shaped exhaust pipe 22, the flexible joint 23, and the underfoot catalyst 24,
The plurality of independent exhaust pipes correspond to the exhaust manifolds 9a, 9b, 9c, 9d,
The steering mechanism corresponds to the steering rack 16,
The present invention is not limited to the above-described embodiment, but includes any vehicle front structure embodiment.

In the present embodiment it has been described in the general vehicle provided with a transmission 12, but it may also be carried out in the front structure of a hybrid vehicle having a motor generator's.

  Further, the combination of exhaust manifolds to be assembled is not limited to that of the above-described embodiment. Further, the number of exhaust manifolds to be collected is not limited to two, and may be three or four. Also good.

The perspective view which showed the characteristic part of the front part structure of a vehicle. The whole side view of the front part structure of a vehicle. The whole front view except an engine. The whole top view including a body frame etc. The whole bottom view including the body frame etc. The detailed side sectional view of the tunnel enlarged portion vicinity. AA arrow directional cross-sectional view. BB sectional view taken on the line. It is explanatory drawing which showed the behavior at the time of the vehicle collision in a side view, (a) is the early stage of a collision, (b) is the middle stage of a collision, (c) is the figure which showed the late stage of a collision. Overall side view showing a reference example of the front structure of the vehicles.

ER ... Engine room CR ... Car compartment 4 ... Dash panel 5 ... Floor panel
6 ... Tunnel 7 ... Engine 8 ... Intake manifold (intake pipe)
9 ... Exhaust manifold
9a, 9b, 9c, 9d ... exhaust manifold (independent exhaust pipe)
11 ... Exhaust port
16. Steering rack (steering mechanism)
20 ... Tunnel expansion part
20a ... Upper wall surface 21A, 21B ... Direct catalyst (catalyst)
23 ... Flexible joint (flexible tube)
24 ... Anne Duff Tsu door Catalyst 31 ... propeller shafts door

Claims (5)

A vehicle front structure in which an engine is disposed horizontally in an engine room at the front of the vehicle, an intake pipe is disposed in front of the engine, and an exhaust pipe is disposed behind the engine,
In the vehicle width direction center of the connecting portion between the dash panel and the floor panel constituting the front wall of the passenger compartment, a tunnel portion that protrudes toward the vehicle interior side and extends in the vehicle front-rear direction is provided.
A tunnel enlarged portion that protrudes greatly toward the vehicle interior side is formed at the front of the tunnel portion, and the exhaust pipe includes a plurality of independent exhaust pipes connected to each cylinder of the engine, and a downstream of the independent exhaust pipe A collective exhaust pipe that collects two independent exhaust pipes on the side,
The two collective exhaust pipes are arranged in parallel in the vehicle width direction at a position corresponding to the tunnel enlarged portion ,
An upper wall surface inclined downward on the rear side of the vehicle is provided in the tunnel enlarged portion,
Set the exhaust port of the engine at a position below the extended line of the upper wall slope,
The exhaust pipe is formed so as to extend downward from the exhaust port at the top of the engine to the vehicle rear side,
Further, the catalyst constituting a part of the collective exhaust pipe is disposed at a position corresponding to the tunnel enlarged portion,
A vehicle front structure in which a flexible tube is arranged behind the catalyst . Propeller shaft that transmits the driving force of the engine to the rear wheels,
The vehicle front structure according to claim 1, wherein the propeller shaft is disposed below the two collecting exhaust pipes. A collecting portion for collecting the exhaust pipes into one behind the two collective exhaust pipes;
The vehicle front structure according to claim 2, wherein the collecting portion is disposed on a side of the propeller shaft. Wherein the vehicle front side of the catalytic converter, the vehicle front structure of <br/> claim 1, wherein placing the steering mechanism to steer the front wheels. The vehicle front structure according to any one of claims 1 to 4, wherein the engine is disposed so that an upper portion of the engine is positioned on a vehicle rear side .

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