JPH027223Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust manifold for an internal combustion engine, and particularly relates to measures against thermal distortion of the exhaust manifold.

[Prior art]

The exhaust manifold of an internal combustion engine is subjected to a large thermal load, so thermal deformation becomes a problem.

First, it is necessary to pay attention to the flatness of the flange surface that is attached to the internal combustion engine body via the gasket. This is because when the flatness of the flange surface becomes distorted due to thermal distortion, the sealing surface pressure due to the gasket decreases.
This is because there is a risk of gas leakage.

The second factor is the position of the mounting hole provided on the flange surface. If this position becomes incorrect due to thermal deformation as before, it becomes difficult to remove the exhaust manifold from the internal combustion engine body. this is,
This is not preferable in terms of workability.

By the way, the cause of the flatness of the flange surface being out of order is thought to be thermoplastic deformation when the exhaust manifold cools and contracts due to the temperature difference between the highest temperature gathering part and the vicinity of the flange. Furthermore, it is thought that the cause of the bolt hole positioning being out of alignment is thermoplastic deformation when the exhaust manifold expands as it is exposed to the heat of the exhaust gas. However, to date, taking measures against one of the above two points has resulted in adverse effects on the other. For example, if you connect each port flange and provide a bridge that forms part of the gasket mounting surface in order to prevent the position of the bolt mounting hole from going out of alignment, the deviation in flatness of the flange surface will become larger. There is.

Certainly, if you install a bridge like the one above,
It is reinforced against thermal deformation in the cylinder arrangement direction. However, the thermal deformation due to expansion is suppressed too much near the gathering portion, so if it continues to cool down, the vicinity of the gathering portion will contract and plastic deformation will become larger than when no thermal load is applied. This is thought to be the cause of the increased warpage of the flange surface. In the future, it will be necessary to take these points into consideration when making improvements to the durability of exhaust manifolds.

[Purpose of invention]

An object of the present invention is to reduce thermal deformation (warpage) of the entire exhaust manifold by suppressing the occurrence of thermoplastic deformation caused by thermal expansion of the exhaust manifold.

[Structure of the idea]

In order to achieve this objective, the exhaust manifold of the present invention has a first branch port that separates in two directions from the collecting part connected to the exhaust pipe, and a second branch port that separates from the first branch port for each cylinder. In the exhaust manifold, ribs are provided to connect the mutually adjacent second branch ports, and the ribs located closest to the gathering portion are more likely to connect the first branch port to the internal combustion engine than the other ribs. It is characterized by extending a lot towards the main body.

[Effect of invention]

With the above configuration, the surface area of the rib closest to the gathering part is increased by extending the rib closest to the gathering part more from the first branch port toward the internal combustion engine body than other ribs. Since the surface area is larger than that of the other ribs, heat dissipation is enhanced in and around the collecting area where the heat load is highest in the exhaust manifold. As a result,
By minimizing the temperature difference between each part of the exhaust manifold, the thermal stress generated inside the exhaust manifold is reduced.

Furthermore, by lowering the mechanical strength of other ribs compared to the mechanical strength of the rib closest to the gathering area, the rib closest to the gathering area (this rib is Compared to the ribs, it is closer to the collection point with the highest thermal load, so it expands the most.)
, the thermoplastic deformation of the ribs closest to the gathering portion is reduced.

[Effect of idea]

The above action reduces thermal stress generated inside the exhaust manifold, thereby reducing thermal deformation of the exhaust manifold. Furthermore, by providing ribs, thermal deformation is not only suppressed by improving mechanical strength, but also the mechanical strength of other ribs is lower than that of the rib closest to the gathering part. By lowering the strength, the thermoplastic deformation of the ribs closest to the gathering portion is reduced, which reduces thermal cracking at the corners of the exhaust manifold.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing an exhaust manifold of a four-cylinder diesel engine. 1 is a flange for mounting between exhaust gases. Exhaust gases sent out from each cylinder are collected into one at a collecting section 2 and sent to the exhaust pipe. From this gathering part 2, the first cylinder goes in two directions to the first and second cylinders and the third and fourth cylinders.
Branch ports 3 and 4 are connected. Continuing,
Second branch ports 5, 6, 7, and 8 are formed that branch from the first branch ports 3 and 4 according to the number of cylinders. Returning to the original, the above-mentioned gathering portion 2 is set closer to the second branch port 6 of the second cylinder due to the mounting position of the exhaust manifold. 1st
As shown in FIG. 2, the exhaust manifold having the above ports has flanges 9, 10, 11,
At 12, it is fixed with a bolt to a cylinder head (not shown) together with a gasket.

By the way, the exhaust manifold of this embodiment is provided with heat insulator mounting flanges 13, 14, 15, 16 and an EGR valve mounting flange 17. Along with these, flanges 9, 10, 11,
Reinforcement ribs 18, 19, 20, 21 towards 12
is provided. The reinforcing ribs 18, 21 are the first
It is provided along the outermost periphery of the streamline formed by the branch ports 3 and 4 and the second branch ports 5 and 8. Further, the reinforcing ribs 19 and 20 are provided along the center of the streamline formed by the first branch ports 3 and 4 and the second branch ports 6 and 7.

Next, ribs 22, 23, and 24 are provided that extend from the first branch ports 3 and 4 toward the engine body. These ribs 22, 23, 24 are the second
The branch ports 5, 6, 7, and 8 are connected to each other. As shown in FIGS. 1 and 3, the distances a, b, and c from the head mounting surface have the following relationship: b<a≦c. That is, the closer the distance from the collecting portion, the more the ribs 22, 23, 24 extend from the first branch ports 3, 4 toward the cylinder head. By the way, the gathering part with a large heat load is
Thermal expansion is suppressed to the greatest extent by the fixed support of the flanges 9, 10, 11, 12 and the ribs 22, 23, 24. Therefore, the closer to the gathering portion, the more susceptible to thermoplastic deformation due to contraction after cooling. Therefore, depending on the magnitude of this influence, the ribs 22, 23, and 24 are also reinforced to prevent thermoplastic deformation. Therefore, consideration has been given to eliminating as much waste meat as possible from the ribs. Further, the ribs 22, 23, 24 also function as fins, and the ribs 22, 23, 24 function as fins.
Promote the flow of heat towards 3 and 24. Therefore, the thermal load applied to the gathering portion is reduced, and the amount of shrinkage after cooling, which affects the degree of thermoplastic deformation, is reduced.

As described above, if the exhaust manifold with ribs of this embodiment is used, the flanges 9, 1
It is possible to simultaneously reduce the flatness of 0, 11, and 12 and the positional deviation of the bolt holes 25 provided in each flange.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an exhaust manifold according to an embodiment of the present invention, FIG. 2 is a top view showing a flange of an exhaust manifold according to an embodiment of the present invention, and FIG. 3 is a top view of an exhaust manifold according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of the provided fins. 3, 4...first branch port, 5, 6, 7, 8...
...Second branch port, 22, 23, 24...rib.

Claims (1)

[Scope of utility model registration request] In an exhaust manifold consisting of a first branch port that separates in two directions from a collecting part connected to an exhaust pipe, and a second branch port that separates for each cylinder from the first branch port, the mutually adjacent second branch ports The exhaust manifold is characterized in that ribs are provided to connect between the two, and the rib located closest to the gathering part extends further from the first branch port toward the internal combustion engine body than the other ribs. .