JPH025889B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine exhaust system, and more particularly, to an engine exhaust system having a multi-cylinder engine body of four or more cylinders equipped with an oil pan, and having a plurality of exhaust passages communicating with a plurality of exhaust ports of the main body. The exhaust passage is 2 at the exit.
The present invention relates to an exhaust system for an engine, in which an exhaust manifold is connected to one outlet, and an exhaust pipe is connected to the outlet of the manifold.

Conventionally, exhaust systems for multi-cylinder engines with four or more cylinders use so-called dual manifolds, which combine multiple exhaust passages that communicate with the exhaust ports of each cylinder into two groups. It is known to improve the volumetric efficiency of intake air into the combustion chamber. However, in order to actually produce this dual manifold while taking into account the shape of the engine body and interference with other devices when the engine is mounted on the vehicle body, technology must be solved in order to obtain the exhaust pipe effect. There are many challenges. For example, in front-engine, front-drive vehicles, especially cross-flow type engines, the exhaust manifold extends forward, but since the gap between the front of the engine body and the radiator is small, dual exhaust manifolds are used. It is necessary to make the thickness as thin as possible. Also, while it is preferable to make the exhaust passage as long as possible in order to obtain the exhaust pipe effect,
When casting a dual manifold, an extremely complicated shape is disadvantageous in terms of manufacturing cost and durability. Further, an exhaust pipe is connected to the outlet of the exhaust manifold, and it is important to consider the structure and arrangement of this connection from the viewpoint of ease of assembly and maintenance.

In view of such conventional circumstances, the first object of the present invention is to simplify the structure of an exhaust manifold by having a length sufficient to obtain an exhaust pipe effect, and to minimize the thickness of the exhaust manifold. To provide an engine exhaust device which is thin and has a structure in which a connecting part between an exhaust pipe and an exhaust manifold is easy to assemble and easy to maintain.

In the first invention that achieves the first object, the bottom of the oil pan is formed into a stepped shape with a step above and below, and the exhaust manifold is individually connected to a plurality of exhaust ports on one side of the engine body that are adjacent to each other. A plurality of exhaust passages that are in communication with each other and are substantially parallel are arranged hierarchically along a plurality of exhaust passages that are substantially parallel and communicate with the other plurality of exhaust ports that are adjacent to each other, and the entire length of each exhaust passage is The exhaust pipe extends from the cylinder head to the oil pan pan along the side of the engine body at approximately equal distances, and its outlet is disposed below the upper stage at the bottom of the oil pan, and the exhaust pipe is located below the higher stage. and connected to the outlet.

Here, in an engine exhaust system, the air-fuel ratio may be controlled by detecting the oxygen concentration in the exhaust gas in order to purify the exhaust gas, and in such a case, an oxygen concentration detection sensor is attached to the exhaust manifold. Therefore, it is desirable that the exhaust system as a whole be simplified without becoming complicated even when the oxygen concentration detection sensor is attached.

Therefore, a second object of the present invention is to provide an engine exhaust system that achieves the first object and further has a simple overall external shape and is equipped with an oxygen concentration detection sensor.

In a second invention that achieves the second object, in addition to the configuration of the first invention, an oxygen concentration detection sensor is attached to the side wall of the engine body near the outlet of the exhaust manifold.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, in FIGS. 1 and 2, an engine body E includes a four-cylinder cylinder block 1, a cylinder head 2 connected to the upper part of the cylinder block 1, It consists of a cylinder head cover 3 that covers the upper part of the cylinder head 2 and an oil pan 4 that is fixed to the lower part of the cylinder block 2. The bottom portion 5 of the oil pan 4 is provided with a step in the vertical direction at an intermediate portion along the cylinder arrangement direction of the cylinder block 1, that is, the left-right direction in FIG. The high stage 6 is arranged on the left side of the stage.

The exhaust manifold Mi is molded by casting,
The first to fourth cylinders correspond to each cylinder of the cylinder head 2.
It is connected to the exhaust ports P1 to P4, extends downward along the side of the engine body E, and has an outlet 7 facing below the upper stage 6 of the oil pan 4.

This exhaust manifold Mi is the engine body E
A pair of branch parts 8, 9 on the side, and those branch parts 8,
It consists of a hierarchical part 10 where 9 are joined, and the first to fourth
First to fourth exhaust passages W1 to W4 are provided which individually communicate with exhaust ports P1 to P4. Engine body E
A branch part 8 is connected to one mutually adjacent exhaust port, that is, the first and second exhaust ports P1, P2, and the other mutually adjacent exhaust port, that is, the third and fourth exhaust ports P3, P4.
A branch portion 9 is connected to the branch portion 9 . First and second exhaust passages W1 and W2, which communicate with the first and second exhaust ports P1 and P2 individually, are formed in parallel to each other within the branch portion 8. Further, the third and fourth exhaust passages W3 and W4, which communicate with the third and fourth exhaust ports P3 and P4 individually, are the first and second exhaust passages W.
1 and W2 are formed in parallel in the branch part 9 at the same level.

A first exhaust passage W that moves from the inside of the branching part 8 to the inside of the hierarchical part 10 at the connection position between the branching parts 8 and 9 and the hierarchical part 10
1 is curved so as to be located on the engine body E side adjacent to the fourth exhaust passage W4, and the second exhaust passage W2 is curved so as to be located on the engine body E side adjacent to the third exhaust passage W3. be done. In this way, in the hierarchical section 10, the first and fourth exhaust passages W1, W4, and the second and third exhaust passages W
2 and W3 are adjacent to each other in two layers, and the exhaust passages W1, W4 and W are in two layers.
2 and W3 are mutually parallel.

In FIG. 3, the outlet 7 of the exhaust manifold Mi is provided with a flange 12 at the end of the layered part 10 for joining to the exhaust pipe 11, and this flange 12 has a pair of outlet ports 13 and 14 connected to each other. Drilled adjacent. One outlet 13 has a partition wall 15.
The first and fourth exhaust passages W1 and W4, which are adjacent to each other in two layers, are in common communication with each other through the partition wall 16. Second and third exhaust passages W2, W
3 communicate in common.

In this way, the exhaust manifold Mi is configured as a so-called dual manifold, but each of the exhaust passages W1 to W4 has approximately the same overall length, and the length is set so that the exhaust pipe effect can be fully exerted. has been done. A cylindrical connecting member 17 having a screw hole is fixed in the middle of this exhaust manifold Mi, and a stay 18 fastened to the cylinder block 1 of the engine body E is fastened to this connecting member 17 with a bolt 19. is,
This supports the middle of the exhaust manifold Mi. The side wall 20 on the side of the engine body E near the outlet 7 of the exhaust manifold Mi has the first and fourth
A mounting hole 21 is formed by cutting out partway through the partition wall 20 that partitions the group of exhaust passages W1 and W4 and the group of second and third exhaust passages W2 and W3. A mounting member 23 having a screw hole 22 communicating with is connected. An oxygen concentration detection sensor 24 is screwed and attached to this mounting member 23, so that the detection portion of this oxygen concentration detection sensor 24 can be connected to the first and fourth exhaust passages W1, W4 or the second and third exhaust passages W2, This means that it can be sensitive to the exhaust gas flowing through W3.

The outlet 7 of the exhaust manifold Mi is arranged so as to face downward from the high stage 6 of the oil pan 4, and the exhaust pipe 11 is located in the space below the high stage 6 so as to be connected to the flange of the outlet 7. 12
is combined with In this way, by being able to arrange the exhaust pipe 11 in the space below the higher stage 6,
The exhaust pipe 11 can be placed at a relatively high position. Furthermore, since the higher stage 6 is disposed on one side of the bottom portion 5, the lubricating oil storage capacity of the oil pan 4 can be maintained relatively large, and the lubricating oil in the oil pan 4 can be transferred from the exhaust pipe 11 to the lubricating oil storage capacity of the oil pan 4. The transfer of heat can be prevented as much as possible.

Next, to explain the operation of this embodiment, the exhaust gas discharged according to the operation of the engine is
It flows from the fourth exhaust ports P1 to P4 to the first to fourth exhaust passages W1 to W4. Moreover, the first to fourth exhaust passages W1 to W4 are the first to fourth exhaust passages W
1, W4, and second and third exhaust passages W
2 and W3, and the exhaust passages W1 to W4 are formed to have approximately the same length, so the volumetric efficiency of intake air into the combustion chamber improves equally for each cylinder due to the exhaust pipe effect. do. The oxygen concentration in the exhaust gas flowing out from the exhaust manifold Mi to the exhaust pipe 11 is detected by the oxygen concentration detection sensor 24, and the air-fuel ratio is controlled based on the detected value.

As described above, according to the first aspect of the invention, the exhaust manifold has a plurality of exhaust passages which are arranged in substantially parallel and individually communicated with a plurality of exhaust ports on one mutually adjacent side of the engine main body, and a plurality of exhaust passages in the other mutually adjacent exhaust manifold. The exhaust passages are arranged along a plurality of exhaust passages that are individually connected to the exhaust ports and are approximately parallel to each other, and extend along the side of the engine body from the cylinder head to the oil pan with the entire length of each exhaust passage being approximately equal distances. , the exhaust passages are conveniently grouped into two groups, and the shape is simple, making it possible to suppress an increase in manufacturing costs during casting and improve durability. In addition, since the exhaust passage is only layered into two layers, the thickness of the exhaust manifold does not increase significantly, and it can be effectively used in front-engine and front-drive vehicles with cross-flow type engines. Can be done. Furthermore, the bottom of the oil pan is formed into a step shape with a step above and below, the outlet of the exhaust manifold is arranged below the higher stage at the bottom of the oil pan, and the exhaust pipe is arranged below the higher stage. Since the exhaust pipe is installed and connected to the outlet, the installation position of the exhaust pipe becomes higher, and the ground clearance when mounted on the vehicle can be increased. Furthermore, since the connection position between the exhaust manifold and the exhaust pipe is located on the side of the oil pan, the connection work is easy to perform, which is advantageous in terms of maintenance.

In the second invention, in addition to the configuration of the first invention,
Since the oxygen concentration detection sensor is attached to the side wall of the engine body near the outlet of the exhaust manifold, in addition to the effect of the first invention, oxygen concentration is added to the space between the exhaust manifold and the engine body, which should normally be a dead space. It becomes possible to arrange the concentration detection sensor, and it is possible to achieve the effect of simplifying the overall external shape.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is an overall front view, FIG. 2 is a partially cutaway side view seen from the right side of FIG. 1, and FIG. 3 is an end view taken along the line - in FIG. It is a diagram. 2...Cylinder head, 4...Oil pan, 5
...Bottom, 6...High stage, 7...Exit, 11...
Exhaust pipe, 24...Oxygen concentration detection sensor, E...Engine body, Mi...Intake manifold, P1~
P4...1st to 4th exhaust port, W1 to W4...
First to fourth exhaust passages.

Claims (1)

[Scope of Claims] 1. A multi-cylinder engine body with four or more cylinders equipped with an oil pan has a plurality of exhaust passages individually communicating with a plurality of exhaust ports of the body, and these exhaust passages have two exhaust passages at the exit. In an exhaust system for an engine, in which an exhaust manifold is connected to an outlet, and an exhaust pipe is connected to the outlet of the manifold, the bottom of the oil pan is formed in a step shape with a step above and below; The manifold includes a plurality of exhaust passages arranged in substantially parallel and individually communicating with one plurality of exhaust ports adjacent to each other in the engine main body.
A plurality of exhaust passages are arranged hierarchically in parallel to each other and individually communicate with other plurality of exhaust ports adjacent to each other, and the entire length of each exhaust passage is arranged at approximately equal distance along the side of the engine body. The exhaust pipe extends from the cylinder head to the oil pan, and its outlet is disposed below a high stage at the bottom of the oil pan, and the exhaust pipe is disposed below the high stage and connected to the outlet. An engine exhaust system featuring: 2. A multi-cylinder engine body with four or more cylinders equipped with an oil pan has a plurality of exhaust passages individually communicating with a plurality of exhaust ports of the body, and these exhaust passages are aggregated into two outlet ports at the exit. In an exhaust system for an engine in which an exhaust manifold is connected and an exhaust pipe is connected to the outlet of the manifold, the bottom of the oil pan is formed in a step shape with a step above and below, and the manifold is connected to the engine body. A plurality of exhaust passages that are substantially parallel and individually communicate with one of the plurality of exhaust ports adjacent to each other,
A plurality of exhaust passages are arranged hierarchically along a plurality of exhaust passages that are arranged in parallel to each other and individually communicate with another plurality of exhaust ports adjacent to each other, and the entire length of each exhaust passage is made approximately equal distance, and the exhaust passages are arranged along the side of the engine body. The exhaust pipe extends from the cylinder head to the oil pan, and its outlet is disposed below the high stage at the bottom of the oil pan, and the exhaust pipe is disposed below the high stage and connected to the outlet, and the exhaust pipe is disposed below the high stage at the bottom of the oil pan and is connected to the outlet. On the side wall of the engine body near the outlet of the manifold,
An engine exhaust system characterized in that an oxygen concentration detection sensor is attached.