JP2003201839A - Exhaust system of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust system of an engine which is compactly laid out and also allows the whole engine to be compactly laid out. <P>SOLUTION: The exhaust system of the engine equipped with an exhaust manifold 20 having exhaust ports 23a-d provided independently corresponding to the number of cylinders is composed of a first converging part 24a where the exhaust ports 23a and 23d positioned at the two ends of the engine in its longitudinal direction converge and a second converging part 24b where the exhaust ports 23b and 23c positioned elsewhere converge, wherein the second converging part 24b is located above the first 24a. A convergence port 25 is provided where the first 24a and second converging parts 24b are integrated, and the outside diameter of the first port 23a farthest from the convergence port 25 and the second port 23b second farthest is made greater than the outside diameter of the other ports 23c and 23d. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine exhaust system.

[0002]

2. Description of the Related Art Usually, an exhaust system of a vehicle has a catalyst device connected to an exhaust manifold so that C is a harmful component in exhaust gas.
Purifying O, HC and NO _x . In order to effectively utilize the catalyst, it is necessary to raise the catalyst temperature to the activation temperature quickly. Therefore, the exhaust manifold upstream of the catalyst device may be formed of a member having a small heat capacity.

Since the exhaust manifold causes hot exhaust gas to flow inside, the surface of the exhaust manifold has a considerably high temperature. Therefore, it is necessary to attach a heat shield plate or heat insulating material to the exhaust manifold to prevent heat damage to other parts. is there. In addition, the engine mounting bracket and the like adjacent to the exhaust manifold may suffer heat damage due to the heat radiated from the exhaust manifold, resulting in a decrease in durability.

Hereinafter, a conventional engine exhaust system according to the prior art will be described in more detail with reference to the drawings. FIG. 6 is a front view showing an arrangement configuration of an engine 1 ′ according to a conventional technique, and FIG. 7 is a side view of FIG. As shown in the figure, the engine 1'is mainly equipped with oil pans 5a, 5b,
It is composed of a cylinder block 2, a cylinder head 3, and a cylinder head cover 4, and is mounted on a vehicle body frame (not shown) with an intake manifold 10 mounted above the engine 1'main body and an exhaust manifold 20 'mounted below. Has been done.

Known exhaust manifolds for vehicles are a single port type in which exhaust is collected at one location and a dual port type in which exhaust interference is avoided. In the example shown in FIG. 7, the exhaust manifold 20 ′ has four exhaust ports 23.
A dual port type including a, 23b, 23c, and 23d, in which the first exhaust port 23a and the fourth exhaust port 23d are assembled by the first collecting portion 24a, and the second exhaust port 23b and the third exhaust port 23c are assembled. The second collecting unit 24b collects them, and finally, the collecting port 25 collects all of them. In this case, the second collecting portion 24b is arranged below the first collecting portion 24a, and the mount rubber bush (elastic body) 31 of the engine mount bracket 30 is arranged below the second collecting portion 24b. However, the second collecting unit 2
Since the mount rubber bush 31 is arranged directly below 4b, the mount rubber bush 31 may be damaged by heat from the exhaust manifold 20 ', and the durability may be reduced. Therefore, in the conventional technique, the mount rubber bush 3 is used.
In order to prevent the deterioration of durability of No. 1, it was necessary to keep the mount rubber bush 31 away from the exhaust manifold 20 '. However, when the mount rubber bush 31 is arranged apart from the exhaust manifold 20 ′, it becomes difficult to configure the engine 1 ′ compactly.

[0006] As a prior art relating to an engine exhaust system, utility model registration No. 2543434, Japanese Patent Laid-Open No. Hei 9
There are those disclosed in JP-A-88579 and JP-A-2001-3743. Utility model registration No. 2543
In the exhaust pipe structure of the engine disclosed in Japanese Patent No. 434,
The fitting portion between the exhaust pipe collecting portion formed by collecting a plurality of upstream exhaust pipes and the one end side of the connecting cylinder has a circular cross section, and the other end side of the connecting cylinder has the axial center of the connecting cylinder. It is formed so as to be inclined with respect to the axial center on one end side, and the direction and position of the other end side of the connection pipe is set to the downstream side exhaust pipe by setting and tilting the rotational position of the connection pipe with respect to the exhaust pipe collecting portion. Corresponding. In the exhaust system for an engine disclosed in Japanese Patent Laid-Open No. 9-88579, an engine arranged such that an output shaft extends in the front-rear direction of a vehicle and an engine mount located in an intermediate portion in the front-rear direction of the engine are provided above the engine mount. And a precatalyst arranged so as to extend in the front-rear direction, and the precatalyst is arranged in a space below the exhaust manifold and above the engine mount bracket. In the exhaust system for an engine disclosed in Japanese Unexamined Patent Publication No. 2001-3743, an exhaust system for an engine mounted on a vehicle is connected to the propulsion shaft driven by the engine in parallel with the exhaust system. Expanded part is provided in the middle part,
The catalyst is housed in the expanded diameter portion, and the expanded diameter portion is provided so as to be oriented in the vehicle width direction and the outward direction.

[0007]

As described above, although various improvements have been made to the exhaust system of the engine, the layout of the entire engine including the layout of the exhaust manifold and the engine mount bracket is not taken into consideration. . In the exhaust system for an engine disclosed in Japanese Utility Model Registration No. 2543434, even if the arrangement of the downstream side exhaust pipe is changed, the other end side of the connecting cylinder corresponds to the changed downstream side exhaust pipe. Therefore, the degree of freedom in connecting the exhaust pipe is increased. Further, in the engine exhaust device disclosed in Japanese Patent Laid-Open No. 9-88579, the precatalyst is arranged in the space below the exhaust manifold and above the engine mount bracket. Isolated from
The only effect is to suppress the effect of cooling by the outside air as much as possible and to maintain the catalytic effect in a good state. In the engine exhaust device disclosed in Japanese Patent Laid-Open No. 2001-3743, the enlarged diameter portion of the exhaust device for accommodating the catalyst is oriented in the vehicle width direction and the outward direction,
The only effect is to cool the catalyst efficiently by ensuring good wind contact with the expanded diameter portion during traveling.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an exhaust system for an engine, which allows a compact layout of the exhaust system for the engine and a compact layout of the entire engine.

[0009]

In order to achieve the above object, the invention according to claim 1 is an engine exhaust system provided with an exhaust manifold having independent exhaust ports for the number of cylinders. A first collecting portion that collects exhaust ports located at both ends in the direction and a second collecting portion that collects exhaust ports that are not located at both ends in the longitudinal direction of the engine are provided, and the second collecting portion is formed from the first collecting portion. Is also located above. With such a configuration, by arranging the two collecting parts constituting the exhaust manifold in the vertical direction, the exhaust device can be compactly assembled, the layout property in the engine room can be improved, and the layout property of the entire engine can be improved. Improve.

The invention described in claim 2 is the same as claim 1.
In the exhaust system for an engine described in, the first collecting portion is located below the horizontal direction when the engine is mounted, and the second collecting portion is located above the horizontal direction when the engine is mounted. Is characterized by. With such a configuration, a compact exhaust device with less protrusion in the engine width direction can be formed, so that adjacent engine mounts can be laid out at optimum positions.

The invention according to claim 3 is the exhaust system for an engine according to claim 1 or 2, wherein:
The number of cylinders is 4, a collecting port that integrates the first collecting portion and the second collecting portion is provided, and the outer diameters of the exhaust port farthest away from the collecting port and the exhaust port second farthest away from the collecting port are set. The outer diameter of the remaining two exhaust ports is larger than that of the other two exhaust ports. With such a configuration, it is possible to improve the strength only in a necessary portion of the exhaust port, to compact the exhaust device, and to reduce the weight of the entire engine.

The engine exhaust system according to the present invention is basically constructed as described above, but the number of cylinders is not limited to four. For example, when the number of cylinders is 6, the first, second, and third exhaust ports are gathered at the first gathering portion,
The fourth, fifth, and sixth exhaust ports may be combined at the second collecting portion. Then, the first collecting portion and the second collecting portion are arranged in the vertical direction to make the exhaust device compact.

[0013]

While the novel features of the invention are set forth with particularity in the appended claims, the invention will be more apparent from the following detailed description in conjunction with the drawings. Hereinafter, an engine exhaust system according to an embodiment of the present invention will be described with reference to FIGS. In order to facilitate understanding, the same members as those according to the related art shown in FIGS. 6 and 7 will be described using the same reference numerals.

FIG. 1 shows a front view of an engine 1 according to an embodiment of the present invention. A side view corresponding to the figure is shown in FIG. As can be understood from both figures, the engine 1 mainly includes the cylinder block 2 and the cylinder head 3.
Composed of and. Further, the engine 1 is provided with oil pans 5a and 5b below, and a lubrication mechanism (not shown) for pumping the oil in the oil pans 5a and 5b to an appropriate place in the engine 1 by an oil pump (not shown). Constitute.
Further, as shown in the figure, the engine 1 is mounted in an engine room E while being inclined. This assumes, for example, a case where the engine 1 needs to be arranged while suppressing the overall height in a limited space E under the floor of the vehicle. In the illustrated embodiment, the engine 1 is mounted with a tilt of about 60 degrees, but the tilt angle may be changed.

An intake manifold 10 is provided above the engine 1, an exhaust manifold 20 is provided below the engine 1, and a catalyst device (not shown) is provided downstream of the exhaust manifold 20.

In the drawings, reference numerals 12, 13, 14, 15
Indicate a timing belt cover, a crank pulley, a water pump pulley, and an alternator pulley, respectively.
At this time, in the timing belt cover 12, the valve mechanism (not shown) of the engine 1 and the crankshaft 13a are synchronized by using a belt mechanism (not shown) or a chain mechanism (not shown). Drive it. Further, via the water pump pulley 14 and the alternator pulley 15, the crankshaft 13 a, the water pump and the alternator are synchronously driven using the belt mechanism 16. Further, in the illustrated engine 1, the mount bracket 30 is used to support the engine 1 from below.
Further, in the embodiment according to the present invention, as shown in FIG. 1, a plurality of exhaust ports 23 forming the exhaust manifold 20 are arranged in the vertical direction, and a mount rubber bush (elastic body) at the tip of the mount bracket 30 is arranged. I try not to contact 31.

Further, in the embodiment according to the present invention, in order to meet the high output demand of the engine 1, the exhaust manifold 20 is of a dual port type to avoid exhaust interference of each cylinder. That is, as shown in FIG. 2, a first collecting portion 24a that collects the first exhaust port 23a and the fourth exhaust port 23d located at both ends in the longitudinal direction of the engine 1 and a central portion in the longitudinal direction of the engine 1 are also located. The second collecting portion 2 that collects the second exhaust port 23b and the third exhaust port 23c
4b, and at this time, the second collecting portion 24b is connected to the first collecting portion 2
It is arranged above 4a. Furthermore, each collective port 24
The a and 24b are vertically arranged to be compactly arranged so as to avoid layout interference with the mount rubber bush 31 on the mount bracket 30.

Here, the exhaust device according to the embodiment of the present invention will be described in more detail with reference to FIGS. As shown in FIG. 3, the exhaust gas discharged from the cylinder of the engine 1 is introduced into the exhaust ports 22a to 22d formed in the mounting flange 21a of the exhaust manifold 20 and diverted in the exhaust ports 23a to 23d. Flow. The exhaust gas split into the exhaust ports 23a to 23d is collected at the collecting port 25 and attached to the mounting flange 21b.
Enters the catalyst device (not shown) from the
O, HC and NO _x are purified. Incidentally, as shown in FIG. 4, after the exhaust ports 23a to 23d are assembled, the collecting port 25 is partially reduced in diameter and mounted on the mounting flange 21b. Further, as shown by reference numeral 26 in FIG. 3, an O ₂ sensor mounting boss is provided on a side portion of the collecting port 25.

As shown in FIG. 3, in the embodiment according to the present invention, in the exhaust manifold 20 consisting of four exhaust ports 23a to 23d, the first exhaust port 23a and the fourth exhaust port 23d are connected to the first collecting portion. 24a, and the second exhaust port 23b and the third exhaust port 23c are assembled by the second collecting portion 24b. At this time, as shown in FIG. 4, the exhaust ports are extended in parallel to allow the exhaust gas inside to flow smoothly, and as shown in FIGS. 4 and 5, the first exhaust port 24a is provided above the first collecting portion 24a. By disposing the two collecting portions 24b, the entire exhaust system is compactly assembled.

Further, as can be seen from FIG. 5, the first
The first collecting portion 24a that collects the exhaust port 23a and the fourth exhaust port 23d is arranged below the horizontal direction H when the engine is mounted, and the second collecting portion that collects the second exhaust port 23b and the third exhaust port 23c. 24b is arranged above the horizontal direction H when the engine is mounted. On this occasion,
If the angle formed by the first exhaust port 23a and the fourth exhaust port 23d with respect to the horizontal direction H is A1, and the inclination angle between the second exhaust port 23b and the third exhaust port 23c is A2, then A1 and A2 are preferably equal. . Further, the length of the first exhaust port 23a and the fourth exhaust port 23d is L1, and the length of the second exhaust port 2 is
When the lengths of 3b and the third exhaust port 23c are L2, L1 and L2 are preferably equal. With such a configuration, the exhaust device according to the embodiment of the present invention does not project in the engine width direction in the engine room E (see FIG. 1).
), Can be laid out compactly. Therefore, as shown in FIG. 1, the exhaust device according to the embodiment of the present invention includes a chassis frame F and an exhaust manifold 2.
A clearance C can be secured between the end portion of 0 and the end portion. Further, the exhaust manifold 20 does not come into direct contact with the mount rubber bush 31. Therefore, in the embodiment of the present invention, since the exhaust manifold 20 and the mount rubber bush 31 do not interfere with each other by compacting the exhaust system, heat damage to the mount rubber bush 31 can be reduced. Further, in the embodiment according to the present invention, it is not necessary to increase the distance between the exhaust manifold 20 and the mount rubber bush 31 more than necessary to increase the layout of the entire engine 1.

Then, referring again to FIG. 3, the outer diameter D1 of the first exhaust port 23a farthest from the collecting port 25.
With the outer diameter D2 of the second farthest second exhaust port 23b, the remaining two third exhaust port 23c and the fourth exhaust port 2
The diameter is set to be larger than the outer diameters D3 and D4 of 3d. In other words,
The outer diameter of the first exhaust port 23a is D1, and the second exhaust port 2 is
The outer diameter of 3b is D2, the outer diameter of the third exhaust port 23c is D
When the outer diameter of the third and fourth exhaust ports 23d is D4, the outer diameter D1 and the outer diameter D2 are preferably the same diameter, and the outer diameter D3 and the outer diameter D are the same.
4 has the same diameter, and the outer diameters D1 and D2 are the outer diameters D3 and D4.
Configured to a larger diameter than. That is, (D1 = D2)> (D3
= D4). This is the long first exhaust port 2
3a and the second exhaust port 23b to the third exhaust port 2
The diameters of 3c and the fourth exhaust port 23d are made small, and the attachment strength of each exhaust port 23a to 23d is improved only at a necessary portion so as to compensate for the unequal length of each exhaust port 23a to 23d. There is. Therefore, it is possible to lay out a compact sheet metal dual exhaust manifold for achieving both exhaust gas performance and output performance.

[0022]

As described above, in the vibration reducing member of the present invention, according to the invention described in claim 1, the exhaust device is made compact by vertically arranging the two collecting portions constituting the exhaust manifold. In summary, it is possible to improve the layout of the engine room and the layout of the engine as a whole.

According to the invention described in claim 2,
In addition to the effect of the invention described in claim 1, since it is possible to form a compact exhaust system with less protrusion in the engine width direction, it is possible to lay out adjacent engine mounts at optimal positions.

According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, the strength of only the necessary portion of the exhaust port is improved, and the exhaust device is compactly assembled. It is possible to reduce the weight of the entire engine.

[Brief description of drawings]

FIG. 1 is a front view showing an arrangement configuration of an engine according to an embodiment of the present invention.

FIG. 2 is a side view showing the arrangement configuration of the engine according to the embodiment of the present invention.

FIG. 3 is a plan view showing an exhaust device according to an embodiment of the present invention.

FIG. 4 is a side view showing an exhaust device according to an embodiment of the present invention.

FIG. 5 is a front view showing an exhaust device according to an embodiment of the present invention.

FIG. 6 is a front view showing an arrangement configuration of an engine according to a conventional technique.

FIG. 7 is a side view showing an arrangement configuration of an engine in the related art.

[Explanation of symbols]

1 engine 10 intake manifold 20 exhaust manifold 23a-23d exhaust port 24a, 24b Assembly section 25 Assembly port 30 engine mount bracket 31 Mount rubber bush (elastic body)

Claims (3)

[Claims] 1. An exhaust system for an engine, comprising an exhaust manifold having independent exhaust ports corresponding to the number of cylinders, a first collecting portion for collecting exhaust ports located at both longitudinal ends of the engine, and a longitudinal direction of the engine. A second collecting portion that collects exhaust ports that are not located at both ends in the direction is provided.
Further, the engine exhaust system is characterized in that the second collecting portion is arranged above the first collecting portion. 2. The first collecting portion is located below the horizontal direction when the engine is mounted, and the second collecting portion is located above the horizontal direction when the engine is mounted. The exhaust system for an engine according to Item 1. 3. The number of cylinders is 4, a collecting port that integrates the first collecting portion and the second collecting portion is provided, and an exhaust port farthest from the collecting port and an exhaust gas farthest from the collecting port. The exhaust system for an engine according to claim 1 or 2, wherein the outer diameter of the port is larger than the outer diameters of the remaining two exhaust ports.