JPH0247235Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention is an intake system for a multi-cylinder internal combustion engine, in particular, the length and shape of the intake passage are substantially variable depending on the engine operating conditions, and the dynamic inertia of the intake system is reduced. The present invention relates to an intake system for a multi-cylinder internal combustion engine that improves the volumetric efficiency of the engine by utilizing the effects.

BACKGROUND ART As an inertial supercharging device for a multi-cylinder internal combustion engine, a second damping volume with a built-in gate valve is connected to an intake pipe downstream of a first damping volume, and the gate valve is controlled to open and close according to the engine speed. There is a system that attempts to obtain a large inertial supercharging effect both at low speed when the valve is closed and at high speed when the valve is opened (Japanese Utility Model Publication No. 116726/1982).

However, even with the above-mentioned device, it is insufficient to obtain good inertial supercharging over the entire operating range of the engine, and in order to improve this, the applicant first set up multiple intake air intakes downstream of the surge tank. The pipes are arranged close to each other, the intake pipes of the closely arranged portions are connected to each other, and a control valve is provided in this communication part, and when the rotation speed is low, the control valve is closed to cut off the communication, and when the rotation speed is high, the control valve is closed. We have proposed an intake system for a multi-cylinder internal combustion engine in which the communication portion is communicated with the control valve by opening it (Japanese Patent Application No. 18458/1982).

Problems to be Solved by the Invention In general, in internal combustion engines, engine performance, especially in high-speed ranges, is greatly influenced by the magnitude of intake resistance. For this reason, various considerations must be taken when designing the intake system, and in order to minimize the flow resistance of the intake pipe, it is desirable that the intake pipe be straight and have no irregularities on its wall. However, in many cases, the intake pipe has to be a curved pipe due to vehicle mounting restrictions. In this case, in view of the state of the intake air flow, special consideration must be given so that the flow resistance on the outer peripheral side of the curved portion of the intake pipe does not increase.

On the other hand, in the above-mentioned type of intake system in which a communication part is provided in the middle of each intake pipe and the opening/closing control is controlled to increase the inertial supercharging effect, there is a step in the communication part of each intake pipe. It is unavoidable that this occurs, and this step increases the intake resistance. If the intake pipe is a curved pipe, the curved passage and the presence of the step further increase the flow resistance of the intake air.

This invention aims to reduce intake resistance even when the intake passages are curved in an intake system in which each intake passage of a multi-cylinder engine is connected by a communication passage, thereby improving engine performance. It is.

Means for Solving the Problems According to the present invention, in order to solve the above problems, a plurality of intake passages curved in the same direction are arranged in parallel on the downstream side of the surge tank, and each intake passage is A communication passage opening in each intake passage is provided so as to communicate with each other, and this communication passage is arranged at a position such that both an upstream side and a downstream side of each intake passage are curved toward the communication passage when viewed from the opening. and the opening portion is located on the inner peripheral side of the curved portion of each intake passage,
The communication passage is provided with a control valve that controls the opening and closing of each intake passage, and this control valve is controlled to be closed in the high load/low and medium speed rotation range of the engine and open in other operating ranges of the multi-cylinder internal combustion engine. An intake device is provided.

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

1 and 2, 1 is a main body of a multi-cylinder internal combustion engine, 2 is an intake manifold, 3 is a surge tank, 4 is an intake duct, and 5 is a throttle valve provided in the intake duct 4.

Intake air flowing in from an air cleaner (not shown) is metered by an air flow meter (also not shown), and enters the surge tank 3 through the intake duct 4. The surge tank 3 has a volume that appropriately damps intake pulsation. The downstream side of the surge tank 3 is an intake passage 2 that leads to each cylinder of the engine body 1.
Intake manifold 2 with a, 2b, 2c, 2d
is connected. Each intake passage 2a, 2b, 2c, 2
d are arranged as close as possible to each other on the side of the surge tank 3. In addition, each intake passage 2a, 2
b, 2c, and 2d are all curved toward the outside of the engine body 1, as shown in FIG.
Further, each intake passage 2a, 2b, 2c, 2d communicates with one horizontal communication pipe 6 at its intermediate portion, and each intake passage 2a, 2b, 2
Intake control valves 7a, 7b, 7c, and 7d are provided for opening and closing between the communication pipe 6 and the communication pipe 6. Further, as shown in FIG. 2, the communication pipe 6 is located so as to open particularly toward the inner circumferential side of the curved portion of each intake passage 2a, 2b, 2c, and 2d.

In this embodiment having the above configuration, when the intake control valves 7a, 7b, 7c, and 7d are closed, they have the same effect as if there were no communication pipe 6, and these intake control valves 7a, When 7b, 7c, and 7d are opened, each intake passage 2a, 2 is opened via the communication passage 6.
b, 2c2d communicate with each other, and the intake pulsations of each cylinder interfere with each other to reduce pressure fluctuations.

The opening/closing control of each intake control valve 7a, 7b, 7c, and 7d is such that it is closed in a high-load, low-to-medium-speed rotation range of the engine, and opened in other operating ranges. FIG. 3 graphically shows the relationship between the opening and closing of this intake control valve and the engine load and speed. Note that the settings of the engine load and rotational speed when the intake control valve is opened and closed vary depending on various design factors, such as the length, cross-sectional area, shape, etc. of the intake passage.

FIG. 4 shows changes in volumetric efficiency when the intake control valve is controlled to open and close. In the figure, the change in volumetric efficiency when the intake control valve is closed is shown by a dashed-dotted line, and the change in volumetric efficiency when it is opened is shown by a broken line. In the low and medium speed range of the engine, when the intake control valve is closed, the damping effect due to the interference of the intake pulsation does not occur, and therefore the volumetric efficiency using the intake pulsation increases (peak A). Conversely, in a high-speed range, opening the intake control valve allows more active use of the interference effect of intake pulsation, so the volumetric efficiency can be made higher than when it is closed (peak B). Therefore, according to this embodiment, the volumetric efficiency shown by the solid line can be obtained by controlling the opening and closing of the intake control valve in accordance with changes in engine speed.

When performing the above-mentioned intake control, in this embodiment, since the intake passages 2a, 2b, 2c, and 2d are arranged in a curved manner, the communication pipe 6 that connects these intake passages is particularly designed. Since the curved portion is located so as to open on the inner circumference side, most of the air in each intake passage flows along the inner wall on the outer circumference side of each intake passage due to the centrifugal force. It is not affected by changes in the shape of the inner wall of each intake pipe due to Therefore, each intake passage 2a,
Even if 2b, 2c, and 2d are curved, the intake resistance will not be particularly increased.

Effects of the invention According to the invention, not only can high volumetric efficiency be obtained over a wide operating range of the engine, but even if each intake passage is arranged in a curved state, the communication pipes of these intake passages can be Since it is located so as to open on the inner circumference side of the curved portion, the inner wall surface on the curved outer circumference side of each intake passage does not change in shape due to the installation of the communication pipe, and most of the intake air can flow along the inner wall surface on the outer circumferential side of this curved portion, and therefore, an increase in intake resistance can be prevented in the intake system of this type of multi-cylinder internal combustion engine.
This results in high engine output.

Further, by arranging the communication pipes inside each intake passage, the entire intake device becomes compact and is advantageous in terms of installation in a vehicle.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is a side sectional view of the same embodiment, and FIG. 3 is a diagram showing the relationship between opening and closing of the intake control valve and engine load and speed.
FIG. 4 is a diagram showing how the volumetric efficiency changes due to the opening/closing control of the intake control valve. 1... Engine body, 2a, 2b, 2c, 2d...
Intake passage, 3...Surge tank, 6...Communication pipe,
7a, 7b, 7c, 7d... Intake control valve.

Claims (1)

[Scope of utility model registration request] A plurality of intake passages curved in the same direction are arranged in parallel on the downstream side of the surge tank, and a communication passage opening in each intake passage is provided so that the intake passages communicate with each other. The upstream and downstream sides of each intake passage are both curved toward the communication passage when viewed from above, and the opening is located on the inner circumferential side of the curved part of each intake passage, and A control valve for controlling the opening and closing of each intake passage is provided in the passage, and the control valve is controlled to be closed in a high load/low to medium speed rotation range of the engine and opened in other operating ranges. .