JPH0519538Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an engine exhaust system.

(Prior Art) The exhaust manifold of a normal engine, for example, an in-line four-cylinder engine, has a first exhaust passage 52 that leads out exhaust from two cylinders located on one side in the cylinder arrangement direction, as shown in FIGS. 7 and 8. and a second exhaust passage 53 that guides exhaust gas from the two cylinders located on the other side, respectively, extend toward the center in the cylinder arrangement direction, and are curved downward into a substantially V-shape. It is made up of a collection.

By the way, in an exhaust manifold having such a configuration, especially an exhaust manifold applied to an engine equipped with a turbo supercharger, the thermal expansion is large due to the large amount of exhaust heat, and there is a large amount of heat inside the exhaust manifold along the above-mentioned exhaust passages 52 and 53. Compressive force P directed toward the exhaust gas collecting portion 54 side and tensile force Q acting in the direction of extending the exhaust gas collecting portion 54 outward are generated, and this excessive thermal deformation force causes the corner portions of the exhaust gas collecting portion 54 to Cracks may occur.

As a means to suppress the occurrence of cracks due to thermal stress in the exhaust manifold, for example,
As disclosed in Publication No. 60-50217, a pair of left and right exhaust passages of an exhaust manifold is arranged such that when the amount of thermal deformation of the exhaust passages reaches a certain amount or more, they come into contact with each other to suppress further thermal contraction. It is known that a stopper is provided to prevent excessive stress concentration from occurring in the exhaust gas collecting section.

However, in this conventional example, the pair of left and right stoppers are spaced apart from each other, so although it is effective against compressive force due to thermal expansion, it is not effective against tensile force. It has almost no effect, and therefore, when looking at the exhaust manifold as a whole, it cannot be said that crack countermeasures have been taken sufficiently.

(Technical background of the invention) In order to effectively suppress such thermal deformation of the exhaust manifold (both due to compressive force and due to tensile force), it is necessary to reduce the compressive and tensile forces that act between the left and right exhaust passages. In order to effectively counteract both, reinforcing ribs may be provided between the two exhaust passages to integrally connect the two exhaust passages.

However, when reinforcing ribs are provided like this,
Although the thermal deformation force is distributed and transmitted to both the exhaust passage section itself and the reinforcing ribs by the reinforcing ribs, in this case, the sharing ratio of the thermal deformation force between the exhaust passage section and the reinforcing ribs, in other words, If the ratio of cross-sectional performance between the two is not set appropriately,
In some cases, an excessive thermal deformation force is intensively applied to the reinforcing rib side, and there is a fear that cracks may occur in the reinforcing rib itself (Phenomenon 1).

On the other hand, as a result of experiments and structural analysis, the present inventors clarified the generation of thermal deformation force when reinforcing ribs are provided between a pair of left and right exhaust passages of an exhaust manifold. In the case of the exhaust manifold 1 of a four-cylinder engine as shown in the figure, the compressive force of the thermal stress is distributed and transmitted to both the exhaust passages 2 and 3 and the reinforcing rib 10 as shown by the arrow P, whereas the tensile force Power is arrow Q
Most of the force acts concentratedly on the reinforcing ribs 10, as shown in FIG. It was also found that the distribution state of the compressive force P and the tensile force Q in the reinforcing rib 10 is a lopsided distribution state in which both of them gradually increase toward the outer end edge 10c side of the reinforcing rib 10. Therefore, the compressive force P and the tensile force Q are reduced by the reinforcing ribs 10.
Reinforcement rib 1 by compressive force P that effectively receives
In order to suppress thermal deformation of the collective passage section 5 of 0,
It is necessary to extend the reinforcing ribs 10 to the front surfaces of the exhaust passages 2 and 3 at the joints with the exhaust passages 2 and 3 (Phenomenon 2).

The inventors of this application have considered the above (phenomenon 1) and (phenomenon 2), and as a result,
In order to suppress the occurrence of cracks in the exhaust passage section and the reinforcing ribs and to effectively suppress the thermal deformation of the collective passage section, (1) the reinforcing rib 10 is connected to the exhaust passage sections 2 and 3 located at both ends in the width direction; At the joint part, it extends from the mounting flange part 4 to the front surface of each exhaust passage part 2, 3, and at the center part in the width direction, it is intended to prevent excessive compressive force from being applied to the reinforcing rib 10. It is necessary to make the cross-sectional performance lower than that of both ends (that is, to make the cross-sectional area smaller), and in that case,
Considering the distribution state of compressive force and tensile force, one way to make the cross-sectional performance of the central part in the width direction of the reinforcing rib 10 lower than that of both ends is to use the outer edge of the reinforcing rib 10, which has a large load per unit area. The idea was that if the cross-sectional performance of the portion 10c side is lowered, the above objective can be achieved more effectively with smaller shape changes (for example, shape changes such as forming a notch or reducing the rib thickness). It is.

(Purpose of the invention) The present invention is an attempt to solve the problems pointed out in the above section of the prior art. It is an object of the present invention to provide an engine exhaust system which prevents the occurrence of cracks and improves its durability.

(Means for Achieving the Object) As a means for achieving the above object, the present invention provides a first exhaust passage portion for guiding exhaust gas from a group of cylinders located on one side in the cylinder arrangement direction, and a first exhaust passage portion on the other side. A second exhaust passage portion for guiding exhaust gas from a group of cylinders located in the second cylinder group extends from the mounting flange portion to the cylinder head side end toward the center in the cylinder arrangement direction, and both exhaust passage portions are connected to the cylinder In an engine exhaust system including an exhaust manifold assembled in a substantially V-shape below an exhaust passage opening position on a head side end face, a first exhaust passage part and a second exhaust passage part of the exhaust manifold are arranged in a substantially V-shaped manner. A substantially flat reinforcing rib is provided at a position near the gathering portion of the first exhaust passage and the second exhaust passage, and extends in a direction substantially parallel to the cylinder arrangement direction. The outer edge of the reinforcing rib located on the opposite side of the mounting flange extends to near the front edge of each of the exhaust passages, and the cross-sectional performance of the reinforcing rib is lower in the center than in both ends in the direction along the cylinder arrangement direction. Furthermore, the outer end edge portion is set to be lower than the mounting flange side portion in the direction orthogonal to the cylinder arrangement direction.

(Function) According to the engine exhaust system of the present invention, (1) Since the reinforcing ribs are provided between the left and right exhaust passages, both compressive force and tensile force generated by thermal deformation are transferred to the exhaust manifold body. Since the thermal stress is distributed and transmitted to both of the reinforcing ribs, there is less concentration of thermal stress at the gathering part of the exhaust passage, and the occurrence of cracks in the exhaust passage or the reinforcing ribs is suppressed accordingly. (2) Exhaust passage of the exhaust manifold Since both ends of the reinforcing ribs connected to the parts extend from the mounting flange part to the front surface of the exhaust passage part, thermal deformation of the gathering part of the exhaust passage part due to the tensile force applied to the reinforcing ribs is effective. (3) Since the cross-sectional performance at the center of the reinforcing rib in the width direction is set lower than the cross-sectional performance at both ends,
The effective cross-sectional performance of the reinforcing rib against compressive force due to thermal deformation of the exhaust manifold is defined by the cross-sectional performance of the central portion of the reinforcing rib, and therefore, the cross-sectional performance of the reinforcing rib is set to be the same throughout its width direction. Compared to the case where the compressive force is applied to the reinforcing ribs, the following effects can be obtained.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. 1 to 6.

(First Embodiment) FIGS. 1 to 3 show an exhaust manifold 1 applied to an in-line four-cylinder automobile engine according to a first embodiment of the present invention. This exhaust manifold 1 includes a first exhaust passage section 2 for guiding exhaust gas from two cylinders located on one side in the cylinder arrangement direction among the four cylinders of the engine main body 40, and a first exhaust passage section 2 for guiding exhaust gas from two cylinders located on one side in the cylinder arrangement direction, and two cylinders located on the other side. A second exhaust passage section 3 for guiding exhaust gas from the two cylinders is extended from the mounting flange section 4 toward the center in the cylinder arrangement direction, and is curved downward into a substantially V-shape to form a collective passage section. It is composed of 5.

Further, in this embodiment, the present invention is applied to a position directly upstream of the collective passage 5 of the exhaust manifold 1, extending approximately between the first exhaust passage 2 and the second exhaust passage 3. A reinforcing rib 10 extending in the horizontal direction is formed. In addition, this reinforcing rib 1
0, as shown in FIGS. 2 and 3, at both ends 10a and 10b, the mounting flange 4 and the front surface 2 of each exhaust passage 2 and 3 are connected to each other.
It is formed to extend to a and 3a. In addition, the front edge 1 of the reinforcing rib 10 is located on the side opposite to the mounting flange 4.
0c is recessed in an arc shape from approximately the center in the width direction (cylinder arrangement direction) toward the mounting flange portion 4 side. Therefore, when considering the cross-sectional performance of this reinforcing rib 10 in two directions, the width direction and the depth direction (direction orthogonal to the cylinder arrangement direction), first of all, in the width direction, the performance is The cross-sectional performance is gradually decreasing. On the other hand, in the depth direction of the reinforcing rib 10, the cross-sectional performance of the front end edge 10d side is lower than that of other parts.

Furthermore, the substantial cross-sectional performance of the reinforcing rib 10 against the compressive force P is defined by the central portion 10d, which has the lowest cross-sectional performance. From this,
In this embodiment, when determining the cross-sectional performance of the reinforcing rib 10, the compressive force P is
The cross-sectional properties of the exhaust passage portions 2 and 3 are taken into consideration so that they can be relatively set so that they can be dispersed at a suitable ratio both on the side and on the reinforcing rib 10 side.

According to the exhaust manifold 1 configured in this way, the exhaust manifold 1 thermally expands under the influence of high-temperature exhaust gas discharged from each cylinder of the engine, and compressive force and tensile force are generated as thermal deformation force inside the exhaust manifold 1. occurs respectively. Of this thermal deformation force, the compressive force is indicated by the arrow P in Figures 1 to 3, respectively.
As shown, the compression force applied to the collective passage part 5 side of the exhaust manifold 1 along the first exhaust passage part 2 and the second exhaust passage part 3, and the compression force applied to the reinforcing rib 10 side, respectively. The force is distributed and transmitted in two directions. Therefore, due to the synergistic effect of increased rigidity of the exhaust manifold 1 due to the provision of the reinforcing ribs 10 and the dispersion effect of the compressive force P, thermal deformation of the collective passage section 5 of the exhaust manifold 1 and the resulting stress concentration can be minimized. As a result, the occurrence of cracks in the collecting passage section 5 is prevented.

Furthermore, in this embodiment, the reinforcing rib 10
The part with the largest load distribution in the depth direction,
That is, by cutting out the front edge 10c of the reinforcing rib 10 as well as the central part 10d in the width direction, the substantial cross-sectional performance of the reinforcing rib 10 can be adjusted appropriately without impairing the tensile force performance (described later) of the reinforcing rib 10. Since the load ratio of the compressive force P to the reinforcing rib 10 and the exhaust passage sections 2 and 3 is adjusted by reducing the compression force P to the reinforcing rib 10 or the exhaust manifold 1 to There is no significant stress concentration, and the occurrence of cracks in these parts is effectively prevented.

On the other hand, in a state where the reinforcing ribs 10 are not provided, as shown in FIG. However, by providing the reinforcing rib 10 between the exhaust passage portions 2 and 3 as in this embodiment, the above-mentioned tensile force is applied to the reinforcing rib 10 portion as shown by the arrow Q in FIGS. 1 to 3. Moreover, it acts in a direction to pull out the reinforcing rib 10 forward (that is, it is supported by the reinforcing rib 10), and in that case,
Since both ends 10a and 10b of the reinforcing rib 10 are formed to extend to the front surface of each exhaust passage section 2 and 3 where the load distribution is the largest, deformation of the collective passage section 5 due to the tensile force Q is effectively prevented. It will be done.

Therefore, occurrence of cracks in various parts of the exhaust manifold 1 is effectively prevented, and its durability is improved.

(Second Embodiment) FIGS. 4 to 6 show an exhaust manifold 1 applied to an in-line four-cylinder automobile engine according to a second embodiment of the present invention. This exhaust manifold 1 has the same basic configuration as the exhaust manifold 1 of the first embodiment,
Therefore, the same functions and effects as those of the first embodiment can be obtained, but especially in this embodiment, in addition to this, the exhaust passages 2 and 3 of the reinforcing rib 10 are , that is, the reinforcing rib 10
The load applied to both ends 10a, 10b of the reinforcing rib 10 is further dispersed in multiple directions to improve the strength of this portion. , vertical ribs 11, 11 are additionally formed, which extend vertically from both ends 10a, 10b to the respective exhaust passages 2, 3, respectively. As a result, the load applied to the reinforcing rib 10 is further distributed and transmitted in two directions at both ends 10a, 10b in the width direction, so that stress concentration at both ends 10a, 10b is further reduced, and the occurrence of cracks is prevented. This will be prevented.

It should be noted that other members shown in FIGS. 4 to 6 are given the same reference numerals corresponding to the members shown in FIGS. 1 to 3, respectively, and their explanations will be omitted.

(Effects of the invention) The present invention has a first exhaust passage section that guides exhaust gas from a cylinder group located on one side in the cylinder arrangement direction, and a second exhaust passage section that leads exhaust gas from a cylinder group located on the other side. Exhaust passage portions extend from the mounting flange portions on the cylinder head side end toward the center in the cylinder arrangement direction, and both exhaust passage portions are located approximately below the exhaust passage opening position on the cylinder head side end surface. In an exhaust system for an engine including an exhaust manifold assembled in a V-shape, a substantially flat reinforcing rib is provided at a position near a joint of a first exhaust passage portion and a second exhaust passage portion of the exhaust manifold. The reinforcing rib is provided across the first exhaust passage portion and the second exhaust passage portion and extends in a direction substantially parallel to the cylinder arrangement direction, while the reinforcing rib is provided on the outer side located on the opposite side of the mounting flange portion. The edge extends close to the front edge of each exhaust passage, and its cross-sectional performance is lower at the center than at both ends in the direction along the cylinder arrangement direction, and in the direction perpendicular to the cylinder arrangement direction. The outer edge portion is set to be lower than the mounting flange side portion.

Therefore, according to the engine exhaust system of the present invention, (1) Since the reinforcing ribs are provided between the left and right exhaust passages, both compressive force and tensile force generated by thermal deformation are transferred to the exhaust manifold main body. Since the thermal stress is distributed and transmitted to both of the reinforcing ribs, there is less concentration of thermal stress at the gathering part of the exhaust passage, and the occurrence of cracks in the exhaust passage or the reinforcing ribs is suppressed accordingly. (2) Exhaust passage of the exhaust manifold Since both ends of the reinforcing ribs connected to the parts extend from the mounting flange part to the front surface of the exhaust passage part, thermal deformation of the gathering part of the exhaust passage part due to the tensile force applied to the reinforcing ribs is effective. (3) Since the cross-sectional performance at the center of the reinforcing rib in the width direction is set lower than the cross-sectional performance at both ends,
The effective cross-sectional performance of the reinforcing rib against compressive force due to thermal deformation of the exhaust manifold is defined by the cross-sectional performance of the central portion of the reinforcing rib, and therefore, the cross-sectional performance of the reinforcing rib is set to be the same throughout its width direction. The compressive force applied to the reinforcing ribs is reduced compared to the case where the reinforcing ribs are cracked, and the occurrence of cracks in the reinforcing ribs is effectively prevented, thereby improving the durability of the exhaust manifold. .

[Brief explanation of drawings]

FIG. 1 is a front view of an exhaust manifold applied to an engine exhaust system according to a first embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of FIG. 1, and FIG. 3 is a longitudinal sectional view of FIG. 4 is a front view of an exhaust manifold applied to an engine exhaust system according to a second embodiment of the present invention, and FIG. 5 is a view shown in FIG. 4.
FIG. 6 is a longitudinal sectional view, FIG. 6 is a view taken along the - arrow in FIG. 4, FIG. 7 is a front view of a conventional exhaust manifold, and FIG. 8 is a view taken along the - arrow in FIG. DESCRIPTION OF SYMBOLS 1... Exhaust manifold, 2... First exhaust passage section, 3... Second exhaust passage section, 4... Mounting flange section, 5... Collective passage section, 10... Reinforcement rib,
11... Vertical rib, 40... Engine body, 41
...Cylinder head.

Claims (1)

[Scope of utility model registration request] A first exhaust passage section that leads out exhaust gas from a cylinder group located on one side in the cylinder arrangement direction, and a second exhaust passage section that leads out exhaust gas from a cylinder group located on the other side.
Exhaust passage portions extend from the mounting flange portions on the cylinder head side end toward the center in the cylinder arrangement direction, and both exhaust passage portions are located approximately below the exhaust passage opening position on the cylinder head side end surface. An exhaust system for an engine equipped with an exhaust manifold assembled in a V-shape, the exhaust manifold having a substantially flat plate located near a gathering part of a first exhaust passage part and a second exhaust passage part. A reinforcing rib extends between the first exhaust passage section and the second exhaust passage section and extends in a direction substantially parallel to the cylinder arrangement direction, and the reinforcing rib is located on the side opposite to the mounting flange section. The outer edge of the exhaust passage extends close to the front edge of each of the exhaust passages, and its cross-sectional performance is lower at the center than at both ends along the cylinder arrangement direction. An exhaust system for an engine, wherein the outer end edge portion is set to be lower than the mounting flange side portion in a direction perpendicular to the arrangement direction.