JPH0530966B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Industrial Application Field The present invention relates to an exhaust manifold for collecting exhaust gas from each cylinder of a five-cylinder engine and guiding it to an exhaust pipe, and in particular, the present invention relates to an exhaust manifold for collecting exhaust gas from each cylinder of a five-cylinder engine and guiding it to an exhaust pipe. The present invention relates to an exhaust manifold for a 5-cylinder engine to prevent this.

(2) Conventional technology The cylinder block of a multi-cylinder engine is connected to an exhaust manifold that collects exhaust gas from each cylinder and guides it to the exhaust pipe. Various forms are used.

In an inline 5-cylinder engine, #1~ from one end side.
It has five cylinders #5, and the ignition is set to occur in the order of #1 → #2 → #4 → #5 → #3.

5a and 5b show a conventional exhaust manifold M used in the above-mentioned five-cylinder engine, and the example in FIG. 5a shows five single pipes extending from each cylinder arranged in the cylinder block 1. S1
~S5 are assembled into one in front of the joining flange 2, and this joining flange 2 is connected to an exhaust pipe 4 having a muffler 3. Furthermore, in the example shown in FIG. 5b, a single pipe S1 extending from the #1 cylinder to the joining flange 2 is merged with single pipes S2 to S5 extending from the #2 to #5 cylinders, respectively. These exhaust manifold M
Since the five single pipes S1 to S5 are assembled into one in front of the joining flange 2, it is called a 5-1 assembly type (see, for example, Japanese Utility Model Application No. 118511/1983).

In the example shown in FIG. 6a, three single pipes S1, S3, and S4 extending from cylinders #1, #3, and #4 are combined into a first collecting pipe D1 in the middle, and #2,
Two single pipes S2 and S5 extending from the #5 cylinder are combined into a second collecting pipe D2 in the middle, and these two collecting pipes D1 and D2 are connected to a joining flange 2. Also, in the example of FIG. 6b, #1,
The single pipes S1, S2, and S5 of the #2 and #5 cylinders are combined into a first collecting pipe D1 in the middle, and
Two single pipes S3 extending from #3 and #4 cylinders,
S4 are combined into a second collecting pipe D2 in the middle, and these two collecting pipes D1 and D2 are connected to a joining flange 2. These exhaust manifold M
It is called a 5-2 collection type because the five single pipes S1 to S5 are gathered into two collecting pipes D1 and D2 in the middle and then connected to the joining flange 2.

In the example of FIG. 7, two single pipes S2 and S5 extending from cylinders #2 and #5 are combined into a first collecting pipe D1 in the middle, and two single pipes S3 and S5 extending from cylinders #3 and #4 are combined into a first collecting pipe D1 in the middle. 2nd with S4 in the middle
These two collecting pipes D1 and D are combined into a collecting pipe D2.
2 and a single pipe S1 extending from the #1 cylinder are connected to the joining flange 2. This exhaust manifold M is called a 5-3 set type because the five single pipes S1 to S5 are combined into three and connected to the joint flange 2.

(3) Problems to be Solved by the Invention In general, in internal combustion engines, considerable pressure fluctuations occur in the exhaust pipe as exhaust is blown out, so this pressure fluctuation can be used to promote air intake into the cylinder. A method is being taken.

Figure 8 shows the exhaust pipe pressure versus crank angle θ°.
It shows the fluctuation of Pex. As is clear from the figure, the pressure in the exhaust pipe reaches its maximum immediately after bottom dead center BCD, and becomes the minimum near top dead center TDC, and in this region where the pressure in the exhaust pipe is small, the opening period E of the exhaust valve and the intake valve A so-called valve weight period O is set in which the opening periods I of the valves overlap. During this valve weight period, the low pressure inside the exhaust pipe propagates into the cylinder to promote intake and improve volumetric efficiency.

Figure 9 shows the pressure inside the exhaust pipe during the valve weight period.
This shows the relationship between volumetric efficiency ηv and PPexo.
As is clear from the figure, it is understood that the smaller the pressure inside the exhaust pipe during the valve weight period, the more the volumetric efficiency improves.

By the way, in a multi-cylinder engine, the intake and exhaust action of a certain cylinder may be significantly inhibited by the exhaust blowing of other cylinders. In other words, during the valve weight period of a certain cylinder, a positive pressure wave of the exhaust blowing of another cylinder may occur. is propagated through the exhaust manifold, which increases the pressure in the exhaust pipe during the valve weight period when the pressure should be low, reducing the volumetric efficiency. Exhaust interference as described above is particularly likely to occur between two cylinders where the ignition order is consecutive and the length of the interconnecting exhaust manifold is short.

As is clear from the above explanation, sections 5a and 5b
The conventional 5-1 exhaust manifolds shown in the figures all have the advantage of being simple and lightweight in structure, but have the disadvantage that exhaust interference occurs between all cylinders.

Furthermore, if the conventional 5-2 exhaust manifold shown in Figures 6a and 6b is used, most exhaust interference between cylinders is prevented, but the ignition order is continuous and the exhaust gases are connected to each other. Two cylinders with short manifold length, i.e. No. 6a
The problem is that exhaust interference occurs between cylinders #1 and #3 in the example shown in the figure, and between cylinders #1 and #2 in the example shown in Figure 6b.

Furthermore, the conventional 5-3 exhaust manifold shown in Fig. 7 has the advantage of preventing exhaust interference between all cylinders, but it requires three pipes to be connected to the joint flange. Therefore, there are problems in that the structure is complicated and the weight increases.

The present invention was made in view of the above-mentioned circumstances, and is an exhaust gas that can prevent exhaust interference between all cylinders in a 5-cylinder engine, has a simple structure around the joining flange, and can be lightweight. The purpose is to provide manifolds.

B. Structure of the Invention (1) Means for Solving the Problems In order to solve the above-mentioned object, the present invention provides a method for solving the problems by using any three cylinders among the five cylinders arranged in one direction on the cylinder block. The three single pipes extending from the cylinder are combined into the first collecting pipe, and the two single pipes extending from the remaining two cylinders are combined into the second collecting pipe.
In an exhaust manifold for a 5-cylinder engine in which the first and second collecting pipes are combined into a collecting pipe and connected to a joint flange, two pipes extending from two cylinders that are ignited in succession among the three cylinders. The first feature is that either one of the single pipes is connected to the middle part of the first collecting pipe in a shifted manner.

In addition to the above features, the present invention also provides first and second features.
Combine the collecting pipes into a third collecting pipe in front of the joining flange, and connect the staggered and connected single pipes to the intermediate part of the first collecting pipe, and connect the two single pipes to the second collecting pipe. A second feature is that the parts are located at different distances from the third collecting pipe.

(2) Effect According to the first feature of the present invention, the firing order of two of the three cylinders connected to the first collecting pipe is consecutive, and the single pipe extending from both cylinders is common. Since it is connected to the first collecting pipe, it is easy to cause exhaust interference, but either one of the single pipes extending from these two cylinders is connected to the middle part of the first collecting pipe in a shifted manner. This causes attenuation and a time delay when the positive pressure wave caused by the exhaust gas from the cylinder that is ignited later propagates to the cylinder that is ignited first, and prevents the pressure in the exhaust pipe from increasing during the valve weight period of this cylinder. Ru.

Also, according to the second feature, since the first and second collecting pipes are combined into the third collecting pipe at a position in front of the joining flange, in addition to the above-mentioned exhaust interference of the two cylinders, the staggered connection a cylinder having a single tube, and a second cylinder in continuous ignition relationship with this cylinder.
A new problem of exhaust interference arises in one of the two cylinders on the collecting pipe side. However, the connecting portion of the staggered connected single pipes to the intermediate portion of the first collecting pipe and the connecting portion of the two single pipes to the second collecting pipe are located at different distances from the third collecting pipe. This causes attenuation and a time delay when the positive pressure wave caused by the exhaust air blowing from the cylinder that is ignited later propagates to the cylinder that is ignited first, which prevents the pressure in the exhaust pipe from rising during the valve weight period of this cylinder. be done.

(3) Embodiments Hereinafter, embodiments of the exhaust manifold for a five-cylinder engine according to the present invention will be described based on the drawings.

FIG. 1 shows a first embodiment of the present invention.
This is an improved version of the conventional 5-2 exhaust manifold shown in FIG. 6a.

As shown in Fig. 1, among the five cylinders #1 to #5 arranged in series in the cylinder block 1, two single pipes S extend from the #3 and #4 cylinders.
3 and S4 are combined into a first collecting pipe D1 in the middle, and the two single pipes S2 and S5 extending from the #2 and #5 cylinders are combined into a second collecting pipe D2 in the middle, and these two collecting pipes are combined into a second collecting pipe D2 in the middle. It is connected to the joining flange 2. Single pipe S extending from the remaining #1 cylinder
1 is connected to the intermediate part of the first collecting pipe D1, and its connection part A is located a distance L from the connection part B of the two single pipes S3 and S4 extending from the #3 and #4 cylinders. are doing. The joining flange 2 is connected to an exhaust pipe 4 having a muffler 3 in the middle to guide exhaust gas to the outside.

Next, the operation of the first embodiment of the exhaust manifold for a five-cylinder engine according to the present invention having the above-described configuration will be described.

Figure 2 shows the single pipe S of the #3 cylinder which is subject to exhaust interference due to the exhaust blowing of the #1 cylinder in Figure 1.
FIG. 3 is a diagram showing fluctuations in the exhaust pipe internal pressure Pex at point P in No. 3; The dashed-dotted line A in the figure shows the pressure inside the exhaust pipe due to the connection of the single pipe S1 of the conventional #1 cylinder (L=0; that is, the conventional example in Figure 6a), which is also shown by the dashed-dotted line in Figure 1. This shows that there is significant exhaust interference due to the high peak value of the exhaust pipe internal pressure Pexo during the valve weight period.

The solid line B in FIG. 2 is #1 according to the present invention.
This shows the case where the connection part of the single pipe S1 of the cylinder to the first collecting pipe D1 is displaced by a distance L = 1, and the peak value of the exhaust pipe internal pressure Pexo during the valve weight period decreases, and there is a delay in the peak position. It is understood that the exhaust interference has been reduced by this.

Moreover, the broken line C in FIG. 2 indicates the distance L as L1.
This shows the case where L2 is larger than , and the decrease in the peak value of the exhaust pipe pressure Pexo during the valve weight period and the delay in the peak position become even more noticeable.
This shows that even greater effects were obtained.

FIG. 3 shows a modification of the embodiment shown in FIG. 1, in which instead of connecting the single pipe S1 of the #1 cylinder to the middle of the first collecting pipe D1, the single pipe S1 of the #3 cylinder is connected to the middle of the first collecting pipe D1.
3 is connected to the middle of the first collecting pipe D1. Even with this configuration, there is no substantial difference in the relative connection relationship between the single pipe S1 of the #1 cylinder and the single pipe S3 of the #3 cylinder, and the same effect as that in Fig. 1 can be obtained. That is clear.

FIG. 4 shows a second embodiment of the present invention, and a third embodiment of the present invention.
This figure shows a 5-2-1 collective exhaust manifold that is a further improvement of the modified example of the first embodiment of the present invention shown in the figure.

That is, this exhaust manifold M is one in which the first and second collecting pipes D1 and D2 in the modification of the previous embodiment are combined into a third collecting pipe D3 at a position in front of the joining flange 2. This is intended to simplify the connection part of the collecting pipe. This 5-2-1
In the collective exhaust manifold, in addition to the above-mentioned exhaust interference between the #1 and #3 cylinders, a new problem arises: exhaust interference between the #5 and #3 cylinders whose ignition order is consecutive. For this purpose, in this example,
The first collecting pipe D of the single pipe S3 extending from the #3 cylinder
The connection part A to the intermediate part of No. 1 and the connection part C to the second collecting pipe D2 of the single pipes S2 and S5 extending from the #2 and #5 cylinders are at a distance H from the starting end D of the third collecting pipe D3.
are placed at different distances.

With this configuration, attenuation and time delay occur when the positive pressure wave caused by the exhaust air blowing from the #3 cylinder, which is ignited with a delay, propagates to the #5 cylinder. Pressure build-up is prevented.

Although the embodiments of the exhaust manifold for a five-cylinder engine according to the present invention have been described in detail above, the present invention is not limited to the above embodiments, and without departing from the scope of the present invention as set forth in the claims. , it is possible to make various minor design changes.

For example, the method of dividing five cylinders into three connected to the first collecting pipe and two connected to the second collecting pipe is not limited to the above example;
It is also possible to do as shown in figure b. Further, the firing order of the cylinders is not limited to that of the above embodiment, but can be set as appropriate depending on the classification of the cylinders.

Further, the distance L in the first embodiment and its modification and the distance H in the second embodiment are not limited to predetermined values, but may vary depending on the characteristics of various five-cylinder engines to which the present invention is applied. It should be determined appropriately through experiments, etc., depending on the situation.

C. Effects of the Invention As described above, the exhaust manifold for a five-cylinder engine of the present invention has a predetermined positional relationship on the exhaust manifold between the single pipes extending from two cylinders whose ignition order is consecutive and which easily cause exhaust interference. Since they are connected together, it is possible to attenuate the positive pressure wave generated by the exhaust air blowing from the cylinder that is ignited later, and furthermore, it is possible to propagate this positive pressure wave with a time delay. This effectively prevents the positive pressure wave from propagating during the valve weight period of the cylinder and causing exhaust interference. Therefore, a decrease in volumetric efficiency due to exhaust interference is prevented, and it is possible to increase engine output.

Further, the number of pipes connected to the joining flange may be one or two, which can contribute to improved space efficiency and weight reduction.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of an exhaust manifold for a five-cylinder engine according to the present invention, FIG. 2 is an explanatory diagram of its operation, and FIG. 3 is a diagram showing a modification of the first embodiment. Fig. 4 shows a second embodiment of the exhaust manifold for a five-cylinder engine according to the present invention, Figs. 5a and 5b show a conventional 5-1 collective exhaust manifold, and Figs. 6a and 6b show a conventional 5-cylinder exhaust manifold. 5
- A diagram showing a 2-set type exhaust manifold, Figure 7 is a diagram showing a conventional 5-3 set type exhaust manifold,
FIG. 8 is a diagram showing the fluctuation of the exhaust pipe internal pressure with respect to the crank angle, and FIG. 9 is a diagram showing the relationship between the volumetric efficiency and the exhaust pipe internal pressure during the valve weight period. D1-D3...Collecting pipe, M...Exhaust manifold, S1-S5...Single pipe, #1-#5...Cylinder, 1...Cylinder block, 2...Joining flange, 3...Muffler, 4... ...Exhaust pipe.

Claims (1)

[Scope of Claims] 1 Among the five cylinders (#1 to #5) arranged in one direction in the cylinder block 1, three single pipes extending from any three cylinders are
At the same time, the two single pipes extending from the remaining two cylinders were collected into a second collecting pipe D2, and these first and second collecting pipes D1 and D2 were connected to the joint flange 2. In the cylinder engine exhaust manifold; either one of the two single pipes extending from two cylinders that are ignited consecutively among the three cylinders is connected to the middle part of the first collecting pipe D1 in a shifted manner. Exhaust manifold for 5-cylinder engines. 2. The first and second collecting pipes D1 and D2 are combined into a third collecting pipe D3 in front of the joining flange 2, and a connection part to the intermediate part of the first collecting pipe D1 of the single pipe connected in a staggered manner; 5. 5 according to claim 1, characterized in that the connecting portion of the single pipe to the second collecting pipe D2 is located at a different distance from the third collecting pipe D3.
Exhaust manifold for cylinder engines.