JPH04252819A - Intake manifold for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a suction tube extension structure for internal combustion engine capable of attaining both inertia charging effect in medium to low speed operating zone and intake resistance reducing effect in high speed operating zone without increasing the volume of a surge tank by employing a structure in which the intake tube extension of a curved shape is extended into the surge tank to obtain the length of the intake tube required for the inertia supercharging. CONSTITUTION:An intake extension tube 7 is formed so that it has a flow passage cross-sectional shape of enlarged inside curvature radius R1, a line connecting at least one point on its open end plane 8 to the center of a connection port 5 is included in the flow passage, and the flow passage cross-sectional area at the curved portion R1 is greater than the area at the open end 8 or at the connecting port 5.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an intake manifold for an internal combustion engine, and more particularly, the invention relates to an intake manifold for an internal combustion engine, and more particularly, it has a curved intake pipe extension protruding inside a surge tank in order to obtain the intake pipe length required for inertial supercharging. Regarding the structure of the intake manifold.

0002

2. Description of the Related Art A technique is known that improves the intake air filling efficiency of an engine by appropriately setting the length and diameter of the intake pipe to produce an inertial supercharging effect in a specific operating range. In these technologies, the length of the intake pipe is determined by the engine type and operating conditions in order to obtain an inertial supercharging effect, and cannot be set freely. For this reason, various ideas have been devised to ensure a predetermined intake pipe length within the limited mounting space. An intake manifold structure is disclosed in which intake pipes from each cylinder protrude into the tank.

The intake manifold of the above-mentioned publication has the intake pipe extension protruding into the surge tank to ensure the required intake pipe length without increasing the mounting space, and the shape of the intake pipe extension protruding into the surge tank. By changing the length, etc., the length of the intake pipe can be adjusted to suit different types of engines.

0004

[Problem to be solved by the invention] In the intake manifold structure in which the intake pipe extension protrudes into the surge tank, it is necessary to secure the required length of the intake pipe extension in the limited space inside the surge tank. Typically, the intake pipe extension within the surge tank is curved to increase the length of the flow path. However, the surge tank itself is required to be downsized mainly due to mounting space issues, and the internal volume of the surge tank is often set to be small. In these cases, the intake pipe extension in the surge tank is formed into a complicated curved shape (for example, a spiral shape), and the curvature of the curved part is made as small as possible to achieve the required intake pipe length.

However, when the intake pipe is curved with a small radius of curvature as described above, intake resistance increases due to the bending. For this reason, if the length of the intake pipe extension is set to produce an inertial supercharging effect in the engine's mid- to low-speed rotation range, the pressure loss of the intake air will become large, especially in the high-speed range, and the engine output will decrease in the high-speed range. A problem arises. To prevent this, if we attempt to reduce the intake resistance by increasing the curvature of the intake pipe extension, the surge tank must be made larger, resulting in problems such as poor responsiveness and increased installation space due to the increased volume of the intake system. occurs. For this reason, when the intake pipe extension is configured to protrude into the surge tank, good engine performance may not be obtained in all operating ranges. The present invention solves the above problems and provides an intake manifold for an internal combustion engine that can achieve a good inertial supercharging effect in medium and low speed ranges and a reduction in intake resistance in high speed ranges without increasing the size of the surge tank. The purpose is to

[0006]

[Means for Solving the Problems] The present invention does not make the intake pipe extension a flow path with an equivalent cross-sectional area as in the past, but expands the flow path toward the inner diameter at the curved portion to form a straight line from the inlet of the extension to the outlet. It is characterized by ensuring a flow path. A surge tank disposed in an intake passage of an internal combustion engine, an intake pipe connecting the surge tank and an intake port of each cylinder, and an intake extension pipe protruding into the surge tank and having a curved shape of the intake pipe. In the intake manifold of an internal combustion engine, the curved intake extension pipe has an inner diameter side of the curved part so as to include a straight line connecting at least one point in the open end opening of the intake extension pipe and the center of the surge tank wall connection port. Provided is an intake manifold for an internal combustion engine, characterized in that the flow path has an enlarged cross-sectional shape, and the cross-sectional area of the flow path at the curved portion is larger than the open end opening area and the connection port area. .

[0007]

[Operation] A straight flow path connecting the extension inlet and outlet is formed on the inner diameter side of the curved part of the intake extension pipe, so in the high-speed operation region where the intake flow rate is high, the intake air flows straight from the inlet to the outlet, reducing intake resistance. Decrease. On the other hand, in the medium and low speed region where inertial supercharging is performed, the intake flow velocity is low and the intake pulsation is large, so the intake flow flows along the outer diameter pipe wall of the curved part of the extension pipe, making it impossible to maintain the same flow path length as before. , it is possible to obtain an inertial supercharging effect.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings. FIG. 5 is a diagram showing a surge tank and an intake extension pipe of an intake manifold to which the present invention is applied. In the figure, 1 indicates a surge tank provided in the intake passage. The surge tank 1 is a tank made of resin or cast metal that is provided to prevent harmful pulsation of the intake air flow and mutual interference of cylinder intake pipe pressure fluctuations, and is connected to the air cleaner side intake passage on one side. The intake inlet 3 is open. Further, reference numerals 5a to 5d in the figure indicate connection ports to which intake pipes from the intake ports of each cylinder are connected.

In this embodiment, the connection ports 5a to 5d have an intake extension pipe 7 inside the surge tank that projects into the surge tank.
a to 7d are attached and the intake pipes to each cylinder are connected to the connection ports 5a to 5d.
5d and each intake pipe to form an intake passage that reaches each cylinder intake port.

As mentioned above, the intake extension pipes 7a to 7d are provided for the purpose of adjusting the length of the intake passage leading to each cylinder in order to obtain a good inertial supercharging effect in the medium and low speed range. In order to obtain length, it is shaped like a spiral curve inside the surge tank. 1 and 2 are enlarged views showing the difference in shape between the intake extension pipe 7 of this embodiment and the conventional intake extension pipe 7'. The shape of an example intake extension pipe 7 is shown. Also, Figure 1(A)
is a front view, and FIG. 1(B) is a side view.

FIGS. 2A, 2B, and 2C are cross-sectional shapes of the intake extension pipe 7 of this embodiment taken along lines A-A, B-B, and C-C in FIG. 1B, respectively. (solid line) and A'-A'
, B'-B', and the cross-sectional shape (dotted line) of the conventional intake extension pipe 7' along lines C'-C'.
The upper left arc portions of each cross-sectional view are displayed so as to overlap. As can be seen from FIGS. 1 and 2, in the conventional intake extension pipe 7', each cross section along the flow path is A'-A', B'-B', C'-C'.
In contrast, in this embodiment, the cross-sectional area of the flow path is kept approximately equal at the curved part of the intake extension pipe 7 (Fig. 1(B)).
)R1 part) is enlarged, and each cross section A-A, B-B
, C-C have different flow path cross-sectional areas. Expansion of the flow path at the R1 portion described above is performed when a straight line (for example, X-Y in FIG. 1) connecting at least one point on the end surface of the open end opening 8 of the intake extension pipe 7 and the center of the connection port 5 is inserted into the flow path. As a result, the cross-sectional area of the flow path near the curved portion is larger than the cross-sectional area of the opening 8 and the connection port 5. Point Z on FIGS. 2(A), 2(B), and 2(C) indicates the passing position of the X-Y straight line in FIG. 1 in each cross section. The intake extension pipe 7 of this embodiment has other parts, such as the outer diameter side of the curved part that defines the effective length of the intake extension pipe (see FIG.
(B) R2 portion), the shape of the open end 8, and the dimensions of the connection port 5 are substantially the same as those of the conventional one.

FIG. 6 is a reference diagram showing a state in which conventional intake extension pipes 7a' to 7b' are installed in the surge tank 1. As is clear from a comparison with FIG. 5, the intake extension pipe 7 of this embodiment has the above shape, so that it can be installed in a surge tank that uses a conventional intake extension pipe 7' without changing the shape of the surge tank. It is.

Next, the state of the intake air flow in the intake extension pipe 7 of this embodiment during operation will be explained in comparison with the conventional intake extension pipe 7'. 3 and 4 show the state of the intake air flow in the intake extension pipe of this embodiment and the conventional shape, respectively.
Figure 4 (A) is a front view corresponding to Figure 1 (A), Figure 3 (B)
, FIG. 4(B) is a side view corresponding to FIG. 1(B). In addition, the white arrows in the figure indicate the intake air flow when the engine is operating at medium and low speeds, and the hatched arrows indicate the intake air flow when the engine is operating at high speeds.

[0014] During medium and low speed operation, this embodiment (Fig. 3)
In both the conventional example (Fig. 4), the flow from the opening end 8 (8') to the connection port 5 (5') flows along the outer diameter side of the curved part that defines the effective intake pipe length, There is no big difference in the flow situation compared to the example. This is because during medium-low speed operation, the intake flow velocity is relatively low, the intake pulsation is relatively large, and the intake flow repeats acceleration and deceleration.
This is because the flow tends to follow the curved shape of the outer diameter side of the intake extension pipe.

On the other hand, when the engine is operating at high speed, the intake flow velocity increases due to the increase in engine speed, and the above-mentioned intake pulsation also becomes relatively small, so that the intake flow is caused by the opening end 8.
It begins to flow from (8') with a large straight speed. In the conventional intake extension pipe 7' (Fig. 4), this straight intake air flow is largely bent near the inner diameter side of the curved part before flowing out from the connection port 5', so the intake resistance becomes large at this part and it is not enough. It is not possible to obtain a sufficient amount of intake air (see the diagonal arrow in FIG. 4).

In contrast, the intake extension pipe 7 (FIG. 3) of this embodiment has a straight flow path (X
-Y), the inner diameter side of the flow path is enlarged at the curved part, so that the straight intake air flows into the intake pipe of each cylinder from the connection port 5 without being bent at this part. Can be done. Therefore, compared to the conventional shape, intake resistance during high-speed operation is significantly reduced, and a sufficiently large intake flow can be ensured.

That is, in the intake extension pipe 7 of this embodiment, when the engine is operating at medium and low speeds, the effective intake pipe length equivalent to that of the conventional shape can be ensured by allowing the intake flow to flow along the outer diameter side of the curved part. It is possible to obtain a good inertial supercharging effect as in the case of the shape of , and when the engine is running at high speed, the intake air can flow linearly from the opening 8 toward the connection port 5, which reduces intake resistance. This makes it possible to secure a sufficient amount of intake air.

[0018]

[Effects of the Invention] The intake manifold of the present invention has the intake extension pipe shaped as described above, and uses a surge tank of the same capacity as the conventional one, thereby achieving a good inertial supercharging effect during medium and low speed operation. This has an excellent effect of simultaneously reducing intake resistance during high-speed operation.

[Brief explanation of the drawing]

[Fig. 1] A front view (Fig. 1 (A)) and a side view (Fig. 1 (B)) showing a comparison of the shapes of the intake extension pipe of the present invention and a conventional intake extension pipe.
)).

[Figure 2] A-A (A'-A'), B-B (B'-
B'), CC (C'-C') is a cross-sectional view of the intake extension pipe flow path along line C-C (C'-C').

FIG. 3 is a diagram showing the flow state of intake air in the intake extension pipe of the present invention.

FIG. 4 is a diagram showing the flow state of intake air in a conventional intake extension pipe.

FIG. 5 is a diagram showing a state in which the intake extension pipe of the present invention is installed in a surge tank.

FIG. 6 is a diagram showing a state in which a conventional intake extension pipe is installed in a surge tank.

[Explanation of symbols]

1...Surge tank 5…Connection port 7...Intake extension pipe 8...Open end

Claims (1)

[Claims] 1. A surge tank disposed in an intake passage of an internal combustion engine, an intake pipe connecting the surge tank and an intake port of each cylinder, and an intake extension having a curved shape of the intake pipe protruding into the surge tank. In the intake manifold for an internal combustion engine, the curved intake extension pipe includes a straight line connecting at least one point in the open end opening of the intake extension pipe and the center of the surge tank wall connection port. An intake for an internal combustion engine, characterized in that the cross-sectional shape of the flow passage is enlarged on the inner diameter side of the curved part, and the cross-sectional area of the flow passage at the curved part is larger than the open end opening area and the connection port area. manifold.