JPH0716031Y2 - Variable intake system for multi-cylinder internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an intake device for a multi-cylinder internal combustion engine, in which a branch and a control valve are provided downstream of the branch between the intake valve and the branch. The present invention relates to a variable intake device in which a volumetric efficiency is improved by utilizing an inertial effect by opening and closing a control valve according to operating conditions.

[Prior Art] Intake devices for internal combustion engines are roughly classified into those shown in FIG. 6 (hereinafter referred to as type I) and those shown in FIG. 7 (hereinafter referred to as type II).

Type I is multi-cylinder (the figure shows the case of 6 cylinders)
Of each of the cylinders a, b, c, d, e, f of the intake pipe P
It consists of a system in which a, Pb, Pc, Pd, Pe and Pf are connected to one surge tank S, and the surge tank S is connected to an air cleaner A by one duct D. This type is disclosed, for example, in Japanese Utility Model Laid-Open No. 58-116726.

Type II is multi-cylinder (the figure shows the case of 6 cylinders)
Each of the cylinders a, b, c, d, e, f is divided into a cylinder group in which the intake strokes do not overlap with each other, that is, a cylinder group of a, b, c and a cylinder group of d, e, f. , Independent intake pipes connected to cylinders belonging to one cylinder group are collected in one intake pipe, that is, Pa, Pb, Pc are collected in Ta,
Pc, Pd, and Pe are assembled in Tb, and the assembled intake pipes Ta and Tb are further assembled in one duct D and connected to the air cleaner A. A surge tank S may be provided in the collecting portion, or the intake pipes may be simply collected. This type is disclosed, for example, in JP-A-48-725.
No. 09 publication.

From the viewpoint of increasing the volumetric efficiency of the air sucked into the cylinder and improving the output characteristics of the intake device,
Type I and Type II have different inertial effects that affect volumetric efficiency and must be discussed separately.
In the case of Type I, the inertial effect is affected by the pressure reflected wave at the distance l ₁₀ from the intake valve to the surge tank S,
In the surge tank S, pressure fluctuations in each cylinder interfere with each other and are smoothed to give the same effect as opening to the atmosphere, and there is almost no effect upstream from the surge tank S. Therefore, the engine speed ES-
In the volume efficiency ηv characteristic, only one peak affected by l ₁₀ as shown in FIG. 9 appears, whereas in the type II, the inertia effect is from the intake valve to the first collecting portion (the first intake portion). Affected by both the pressure reflected wave of the distance l ₁₀ to the pipe collecting portion) and the pressure reflected wave of the distance l ₁ from the intake valve to the second collecting portion (the second collecting portion of the intake pipe), Engine speed ES-volume efficiency ηv characteristics as shown in Fig. 10
This is because two peaks affected by l ₁₀ and l ₁ appear. In this case, the peak affected by l ₁₀ appears on the higher engine speed side than the peak affected by l ₁ . That is, type I and type II utilize the principle that one peak or two peaks are different, and by utilizing them, the intake system is designed so that the high volumetric efficiency range comes to the usage range.

The present invention is an improvement of those belonging to type II among the above types.

In the type I intake system, in order to obtain high volume efficiency over the widest possible range of engine speed, Japanese Utility Model Publication No. 57-68123 discloses all intake pipes Pa, Pb, Pc,
As shown in FIG. 8, Pd, Pe, and Pf are provided with branches Ba, Bb, Bc, Bd, Be, and Bf between the intake valve and the intake pipe collecting portion to connect the branch with the intake pipe. By installing a control valve on the control valve and opening / closing the control valve according to the engine operating conditions, the peak of l ₁₀ in FIG. 9 is shifted to the large or small side of the engine speed as shown in FIG. What has been done is proposed.

The above is the variable intake system in which the branch and the control valve are provided in the type I, but there is no known document that the type II is provided with the branch and the control valve to control the volumetric efficiency.

[Problems to be Solved by the Invention] However, the conventional variable intake system disclosed in Japanese Utility Model Laid-Open No. 57-68123 has the following problems.

That is, in the type I intake device, as shown in FIG.
_Since only one peak affected by ₁₀ appears, it is necessary to move the range where high volume efficiency can be obtained over the entire range of low, medium and high engine speeds even if the peak is shifted to the left or right. However, it is difficult to obtain high volumetric efficiency characteristics over the entire rotation range.

An object of the present invention is to make it possible to obtain high volume efficiency over a wide range of engine speed in the type II variable intake system.

[Means for Solving the Problems] A variable intake system for a multi-cylinder internal combustion engine according to the present invention for achieving the above object is obtained by dividing each cylinder of the multi-cylinder internal combustion engine into a group of cylinders whose intake strokes do not overlap. Each cylinder belonging to each cylinder group is connected by a plurality of independent first intake pipes connected to the cylinder to a second intake pipe provided one for each cylinder group, and assembled. In the intake system of a multi-cylinder internal combustion engine in which the second intake pipes, one for each cylinder group, are connected to one duct to be assembled, and the ducts are connected to an air cleaner, Each of the plurality of first intake pipes is individually provided with a branch composed of a pipe whose end opposite to the branch from the first intake pipe is closed, and the branch of the branch from the first intake pipe is provided. A control valve that can be opened and closed is installed in the The peak of volumetric efficiency due to the collecting portion of the pipes is matched to the low speed range, and the peak of the volumetric efficiency due to the collecting part of the first intake pipe when the control valve is closed is matched to either the medium speed region or the high speed region, The peak of the volumetric efficiency due to the branch when the control valve is opened is matched with the other of the medium speed range and the high speed range, and the control is performed when the engine speed becomes the other of the medium speed range and the high speed range when the control valve is closed. The control valve is opened and closed according to engine operating conditions so that the valve is opened.

[Operation] In the above variable intake device, when the control valve is opened and the operation of the branch occurs, of the two peaks that appear when the branch does not open, the peak that appears on the high engine speed side is affected by the branch. Shift to the left and right. This peak shifts to the lower side of the engine speed when the branch is short and thin, and shifts to the higher side of the engine speed when the branch is long and thick.

The reason why the peak is shifted to the left and right by providing the branch is that when the branch is short and thin, the natural frequency becomes low and the flow inertial effect strongly appears on the low rotation side, and conversely when the branch is long and thick, This is because the natural frequency becomes high and an effect close to opening to the atmosphere appears, and the inertial effect of the flow becomes strong on the high rotation side.

The intake system is designed so that the two peaks that appear when the branch is not provided are divided into the low speed region and the high speed region. In the intake system, when a short and thin branch is installed, the engine speed becomes the middle speed region. The control valve is opened to switch the volume efficiency characteristic in the engine middle speed range to the characteristic that influences the branch to improve the volume efficiency in the engine middle speed range, and the high volume efficiency is achieved over the entire range of low, medium and high engine speeds. To get

On the other hand, the two peaks that appear when the branch is not installed are relatively close to each other, and in the intake system designed to appear in the low speed range and the medium speed range, a long and thick branch is attached and the engine speed is high. When it becomes, the control valve is opened to improve the volume efficiency in the engine high speed range,
High volume efficiency should be obtained over the whole range of medium and high speed.

In the above, according to the present invention, the intake stroke is divided into cylinder groups that do not interfere with each other, for example, a cylinder group including # 1, # 2, and # 3 cylinders and a cylinder group including # 4, # 5, and # 6 cylinders. In each cylinder group, each first intake pipe is individually provided with a branch, and the control valve of the branch is opened and closed. Therefore, the interference of intake pulsation does not occur, and the intake pulsation in one intake cycle is not generated. And a large inertial effect can be obtained. Therefore, the peak of the volumetric efficiency that appears when the control valve is switched to the open state is high, the high volumetric efficiency is obtained over a wide range of the engine speed, and the desired improvement of the engine output is achieved.

The above can be applied both for gasoline engines and for diesel engines.

[Embodiment] A preferred embodiment of a variable intake system for a multi-cylinder internal combustion engine according to the present invention will be described below with reference to the drawings.

FIGS. 1, 2, and 5 show the configuration of a system according to an embodiment of the present invention, and FIGS. 3 and 4 show characteristics that can be said for the embodiment of the present invention. The intake stroke timing of the cylinder shown in FIG. 12 described in the conventional example is also applied to the embodiment of the present invention.

In FIG. 1, FIG. 2 and FIG. 5, 1 is a multi-cylinder engine (6 cylinders in the figure), and exhaust gas flows out through the exhaust manifold 2.

When the cylinders are ignited in the order of # 1 → # 5 → # 3 → # 6 → # 2 → # 4, the intake stroke of each cylinder is as shown in FIG. 12, and the cylinder groups where the intake strokes do not overlap Is # 1, # 2,
There are a cylinder group including # 3 cylinders and a cylinder group including # 4, # 5, and # 6 cylinders. The cylinders are divided into cylinder groups whose intake strokes do not overlap. Each cylinder group has a first independent
Intake pipes 3a, 3b, 3c and first intake pipes 3d, 3e, 3f are connected to independent surge tanks 4a, 4b, one for each cylinder group. The mutually independent surge tanks 4a, 4b are connected to mutually independent second intake pipes 7a, 7b provided for each cylinder group, respectively. 7b are connected to one duct 8 to be assembled, and the duct 8 is connected to an air cleaner 9. However, the first intake pipe may be directly connected to the second intake pipe without providing the surge tanks 4a and 4b to be assembled. An intake valve is provided at each cylinder inlet of each of the first intake pipes 3a, 3b, 3c, 3d, 3e, 3f and is opened during an intake stroke.

In the middle of the first intake pipes 3a, 3b, 3c and 3d, 3e, 3f provided for each cylinder, the first intake pipes 3a, 3b, 3c, 3
The branches 6a, 6b, 6c, 6d, 6e, 6f, which are pipes whose ends opposite to the branches from d, 3e, 3f are closed, are the first intake pipes 3a, 3b, 3c, 3d, 3e, It is attached to each of the 3f so as to communicate individually, and the branches 6a, 6b, 6c, 6d, 6e, 6f
A control valve 5 that can be opened and closed is provided at a branch portion from the first intake pipes 3a, 3b, 3c, 3d, 3e, 3f.

Engine speed of intake system when branch is not provided
In the intake system where the peak of the ES-volume efficiency ηv characteristic appears in the low speed region and the high speed region of the engine speed, the branches 6a, 6b, 6c, 6d, 6e, 6f are short and thin, and the engine is installed. The control valve 5 is opened when the rotation speed is medium speed. In the intake system where peaks appear in the low speed range and the medium speed range when the branch is not provided, thick and long branches 6a, 6b, 6c, 6d, 6e, 6f are installed, and the engine speed is high. At that time, the control valve 5 is opened. In this control, the engine speed is detected by the engine speed sensor, the engine load is detected by the accelerator opening sensor, etc., and these signals are sent to the CPU for calculation.
The output is used to drive the actuator, and the control valve 5 is opened and closed via the rod.

FIG. 5 shows the system of the present invention in comparison with the conventional system of FIG.

As the control valve 5, a butterfly valve is used so that the valve receives the flow pressure and the open / close control of the valve is not disturbed. In the opening / closing direction of the butterfly valve 5, the valve plate is the first intake pipe 3a, 3b,
3c, 3d, 3e, 3f perpendicular to the flow of the flow through the first intake pipe 3a, 3b, 3c, 3d, 3e, so as not to disturb the flow
It is desirable to install in parallel with the flow in 3f.

Next, the operation of the system of the embodiment of the present invention will be described.

The engine speed sensor and the engine load sensor detect engine operating conditions, and the control valve 5 is simultaneously opened and closed according to the engine operating conditions.

Intake system where peaks appear when the branch is not installed, which are divided into the low speed range and the high speed range. Branches 6a, 6b, 6c, 6
When d, 6e, and 6f are short and thin, the control valve 5 is opened when the engine speed is in the medium speed range, and the others are closed. When the control valve 5 is closed, one of the two peaks appears in the low speed region and the other appears in the high speed region as shown by the curve (X) in FIG. When the control valve 5 is opened, the peak in the high speed range of the two peaks becomes
As shown by the curve (Y) in FIG. 3, it shifts to the low rotation side, and high volume efficiency is obtained even in the medium speed range. As a result, high volumetric efficiency as shown by the curve (Z) in FIG. 3 is obtained over the entire range of low, medium and high engine speeds. That is,
The valley between the two peaks is filled.

In the intake system, the peaks when the branch is not installed appear in the low speed range and the medium speed range, and the branches 6a, 6b, 6c, 6d, 6e,
When a long and thick 6f is used, the control valve 5 is opened when the engine speed reaches the high speed range, and the others are closed. When the control valve 5 is closed, two peaks appear in the low speed region and the medium speed region as shown by the curve (X) in FIG. When the control valve 5 is opened, the peak in the medium speed range of the two peaks shifts to the high rotation side as shown by the curve (Y) in FIG. 4, and high volume efficiency is obtained even in the high speed range. As a result, high volumetric efficiency as shown by the curve (Z) in FIG. 4 can be obtained over the entire range of low, medium and high rotational speeds. That is, the range in which high volumetric efficiency is obtained spreads toward the high speed range.

Here, in the communication of the first intake pipes 3a, 3b, 3c, 3d, 3e, 3f by the surge tanks 4a, 4b or the second intake pipes 7a, 7b of the present invention, the cylinders whose intake strokes do not overlap are communicated with each other. Since the # 1, # 2, and # 3 cylinders are in communication with each other and the # 4, # 5, and # 6 cylinders are in communication with each other, the intake stroke is heavy. There is no reduction in intake negative pressure due to intake pulsation interference between Nau cylinders,
A large inertia effect can be obtained. Therefore, due to the large intake inertia effect, high volume efficiency can be obtained in any rotation range of the engine, and high volume efficiency and improvement of output performance can be obtained over a wide rotation range of low, middle, and high rotation of the engine.

[Advantages of the Invention] According to the variable intake system for a multi-cylinder internal combustion engine of the present invention,
A branch is provided for each of the intake pipes, a control valve is provided at a branch portion from the first intake pipe of the branch, and a peak of volumetric efficiency due to a collecting portion of the second intake pipe is matched with a low speed region, and a control valve is provided. The peak of the volumetric efficiency due to the first collecting portion of the intake pipe when closed is matched with one of the medium speed range and the high speed range, and the peak of the volumetric efficiency due to the branch when the control valve is opened is within the medium speed range and the high speed range. By matching the other of the control valve and the engine speed when the control valve is closed, the medium speed range and the high speed range, so that the control valve is opened, by opening and closing the control valve, By changing the natural frequency of the intake system, it is possible to expand the region where high volume efficiency is obtained to the high rotation side, or to fill the valley of volume efficiency between the low and high rotation regions. , Engine speed low, medium, high It is possible to obtain the maximum inertia supercharging effect over frequency. Moreover, since the cylinders are divided into cylinder groups whose intake strokes do not overlap with each other and the first intake pipe is provided with a branch individually, it is possible to prevent pressure interference in the cylinder pipes.

Moreover, by appropriately selecting the diameter and length of the branch, the peak can be shifted in a desired direction, so that the branch position of the branch can be selected relatively freely, and the degree of freedom in space design is improved.

[Brief description of drawings]

FIG. 1 is a system diagram of a variable intake system for a multi-cylinder internal combustion engine according to an embodiment of the present invention, FIG. 2 is a sectional view of a branch portion of the device of FIG. 1, and FIG. Thus, an engine speed-volume efficiency characteristic diagram for a thin case, FIG. 4 is an engine speed-volume efficiency characteristic diagram for a long and thick branch of the present invention, FIG. 5 is a schematic system diagram of the present invention, and FIG. 6 is Fig. 7 is a system diagram of a conventional type I intake system, Fig. 7 is a system diagram of a conventional type II intake system, Fig. 8 is a system diagram of a conventional variable intake system of type (type I) of Fig. 6, FIG. 9 is a conventional type I volume efficiency characteristic diagram, FIG. 10 is a conventional type II volume efficiency characteristic diagram, FIG. 11 is a conventional variable intake system volume efficiency characteristic diagram of FIG. 8, and FIG. 12 is It is an intake stroke timing diagram between each cylinder. 3a, 3b, 3c, 3d, 3e, 3f ...... First intake pipe 5 ...... Control valve 6a, 6b, 6c, 6d, 6e, 6f ...... Branch 7a, 7b ...... Second intake pipe 8 ...... Duct 9: Air cleaner

Claims (1)

[Scope of utility model registration request] 1. A cylinder of a multi-cylinder internal combustion engine is divided into cylinder groups whose intake strokes do not overlap each other, and each cylinder belonging to each cylinder group is connected to the cylinder by a plurality of independent first intake pipes. The second intake pipes provided for each of the cylinder groups are connected and assembled, and the second intake pipes provided for each cylinder group are connected to one duct to be assembled. In an intake system for a multi-cylinder internal combustion engine in which the duct is connected to an air cleaner, each of the plurality of first intake pipes belonging to each cylinder group is closed at an end opposite to a branch from the first intake pipe. Each branch is made up of
A control valve that can be opened and closed is provided at a branch portion of the branch from the first intake pipe, and a peak of volumetric efficiency due to a collecting portion of the second intake pipe is matched with a low speed region, and the first intake air when the control valve is closed. The peak of the volumetric efficiency due to the collecting portion of the pipes is matched to one of the medium speed range and the high speed range, and the peak of the volumetric efficiency due to the branch when the control valve is opened is matched to the other of the middle speed range and the high speed range, The control valve is opened and closed according to engine operating conditions so that the control valve opens when the engine speed becomes the other of the medium speed range and the high speed range when the control valve is closed. Variable intake system for multi-cylinder internal combustion engine.