JPH0754092B2 - Engine intake system - Google Patents

Description

The present invention relates to an intake device for an engine.

(Prior Art) Conventionally, two intake ports are provided in one cylinder, and independent intake passages are connected to the intake ports, respectively, and one intake port is operated during low-speed low-load operation in which the intake demand of the engine is small. It is said that the intake air is introduced from both intake passages at the same time during high-speed, high-load operation when the intake demand of the engine is high, and the intake filling efficiency is increased during high-speed, high-load operation to increase the engine output. The technical idea is known (for example, JP-A-55-25
(See Japanese Patent No. 550).

However, this known example attempts to increase the intake charging efficiency by increasing the passage area of the intake passage, and therefore the intake air pressure cannot be increased above atmospheric pressure (ie Therefore, there is a limit to the improvement of intake charging efficiency.

(Object of the Invention) The present invention is intended to solve the problems pointed out in the above-mentioned prior art, and in any one of the high-speed operating region, the high-load operating region, and the high-speed high-load operating region of the engine. Makes it possible to obtain a high level of intake charging efficiency throughout the engine operating range by effectively acting on the supercharging effect of intake air and effectively operating the intake inertial effect in operating areas other than the above operating areas. An object is to provide an intake device for an engine.

(Means for Achieving the Purpose) As a means for achieving the above object, the present invention provides a single cylinder with a front-closed intake port and a rear-closed intake port having different closing timings, and the plurality of intake ports. Independent intake passages that communicate with each other are provided, and the closed intake air is provided between the plurality of intake passages in any one of the high-speed operation region, the high-load operation region, and the high-speed high-load operation region of the engine. The plurality of intake passages are located at a position where the compression wave of the intake air generated by the closing operation of the first-closed intake port can be propagated to the intake air on the rear-closed intake port side between the closing timings of the port and the rear-closed intake port. A communication passage is formed to communicate between the intake passage and the intake passage on the side of the previously closed intake port in the operating region of the engine excluding the operating region. Is provided with an appropriate intake flow control means that functions to prevent intake from the rear closed intake port into the working chamber via the communication passage.

(Operation) According to the present invention, the following effects can be obtained by the above means.

(1) In the low-speed operation region, low-load operation region, low-speed low-load operation region, etc. of the engine, a part of the intake air on the first closed intake port side is passed through the communication passage by the intake flow control means provided in the communication passage. Since the flow is divided into the closed intake port side and is prevented from being introduced into the working chamber from the post-closed intake port side, a decrease in the intake flow velocity on the front closed intake port side is prevented in advance, and the inertia of the intake air is reduced accordingly. The effect will work effectively.

(2) In a high-speed operation region, a high-load operation region, a high-speed high-load operation region of an engine, etc., a compression wave generated during intake on the side of the first-closed intake port due to the closing operation of the first-closed intake port passes through the communication passage. Since it propagates to the rear-closed intake port side before the closing timing, the intake air is forcibly pushed into the working chamber by the wave energy of the compression wave on the rear-closed intake port side, and the intake charge is filled by the supercharging effect. Efficiency is improved.

(Effects of the Invention) Therefore, according to the intake system for an engine of the present invention, in the high-speed operating region, the high-load operating region, or the high-speed high-load operating region of the engine, due to the intake supercharging effect, and in the other operating regions. With the intake air inertial effect, the intake air charging efficiency is increased, so that it is possible to obtain a higher level of output torque throughout the entire operating range of the engine.

(Embodiment) A preferred embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

I: Structure FIG. 1 shows a four-cylinder engine for an automobile according to an embodiment of the present invention. In the figure, reference numeral 1 is four cylinders 1.
It is the engine body with 1,11 ... Each of the cylinders 11, 11, ... Of the engine body 1 has two intake ports, that is, a first intake port 12A and a second intake port 12B, and two intake ports, that is, a first exhaust port 13A and a second exhaust port. Has 13B and.

As shown in FIG. 2, the two intake ports 12A and 12B are provided with a predetermined difference in the closing timing so that the first intake port 12A closes earlier than the second intake port 12B. Has been. Therefore, in this embodiment, the first
The intake port 12A corresponds to the first closed intake port in the claims, and the second intake port 12B corresponds to the second closed intake port in the claims.

On the end surface 1a on the intake port forming side of the engine body 1, mutually independent intake passages connected to the first intake port 12A and the second intake port 12B of the cylinders 11, 11 ,.
That is, the intake manifold 2 is installed in which four first intake passages 21A and four second intake passages 21B are alternately arranged. First intake passage formed for each cylinder
Between the first intake passage 21A and the second intake passage 21B,
When the passage area between the second intake passage 21B and the passage area of the second intake passage 21B is set to be larger than the passage area of 21A, and the operating state of the engine is in an operating region other than the high-speed and high-load operating region In order to obtain the intake inertia effect in each of the intake passages 21A, 21B (that is, the negative pressure wave generated in each of the intake passages 21A, 21B by the opening operation of the intake ports 12A, 12B is reversed in the surge tank 4). The passage length is set so that it can reach the intake ports 12A and 12B as a positive pressure wave immediately before the closing timing and push the intake air into the working chamber.

A communication passage 22 is formed between the first intake passage 21A and the second intake passage 21B so that the two intake passages can communicate with each other. Each intake port 12A, 12B of the communication passage 22
The formation position and the passage area thereof are set according to the closing operation phase of the pair of intake ports 12A, 12B, the propagation velocity of the compression wave of air, and the like.

That is, the formation position and the passage area of the communication passage 22 are such that when the first intake port 12A is closed and the compression wave of the intake air is generated in the first intake passage 21A in the high-speed and high-load operation region of the engine, as described later in detail. , The compressed wave propagates to the second intake passage 21B side through the communication passage 22 and near the closing timing of the second intake port 12B, in other words, between the closing timings of both the intake ports 12A and 12B. Is set as appropriate.

Further, each of the above-mentioned communication passages 22, 22 provided for each cylinder has an on-off valve 2 for controlling the opening and closing of each communication passage 22, 22 ,.
3,23 ... are installed. These on-off valves 23, 23 ...
Is opened and closed simultaneously by an actuator 25 which operates in response to a control signal from the computer 9. Particularly, in this embodiment, the present invention is applied to the high speed and high load operation range of the engine as shown in FIG. The operating mode is set so that the valve opens only at. In this embodiment, the open / close valve 23 corresponds to the intake air flow control means in the claims.

An injector 24 is attached to the first intake passage 21A at a position upstream of the communication passage 22 at the intake side. The injection characteristics (injection amount and injection timing) of the injector 24 are controlled by a control signal from the computer 9.

A surge tank 4 having an appropriate volume is formed at the intake upstream end of the intake manifold 2, and an air cleaner 5, an air flow meter 6, and a throttle valve 7 are provided on the upstream side of the surge tank 4 from the intake upstream side. They are installed sequentially toward the downstream side of intake air. Also, the throttle valve 7
The opening degree of is detected by the throttle opening sensor 10.

On the other hand, the end surface 1b of the engine body 1 on the side where the exhaust ports 13A and 13B are formed has the mutually independent exhaust passages connected to the exhaust ports 13A and 13B, that is, the first exhaust port.
An exhaust manifold 3 in which four sets of 13A and a second exhaust port 13B are formed is connected, and a catalytic converter 8 is mounted on the exhaust downstream side of the exhaust manifold 3.

II: Operation and Action Next, the operation and action of this intake device will be described.

When the engine is operated, intake air is normally open in the first intake passage 21.
The first intake port 12A through both A and the second intake passage 21B
And the second intake port 12B are introduced into the working chamber with a predetermined phase difference, and are mixed with fuel injected from the injector 24 to form a mixture, which is burned in the working chamber.

By the way, when the operating state of the engine is in an operating region other than the high speed and high load operating region, the intake demand of the engine is smaller than in the high speed and high load operating region. For this reason,
When the first intake passage 21A and the second intake passage 21B communicate with each other through the communication passage 22, from the first intake passage 21A on the first intake port 12A side that opens before the second intake port 12B. A part of the introduced intake air is branched to the second intake passage 21B side, and as a result, the flow velocity of the intake air flowing through the first intake passage 21A side is reduced, and the intake inertia effect is impaired. or,
The injector 2 is installed on the side of the first intake passage 21A where the intake flow velocity is high.
Although it is intended to promote the vaporization and atomization of the fuel by providing 4, the fuel vaporization and atomization action decreases from the place where the intake flow velocity decreases, and the combustibility deteriorates.

However, in this embodiment, the present invention is applied as described above, and in such an engine operating region, the opening / closing valve 23 provided in the communication passage 22 is closed to close the first intake passage 21A and the second intake passage 21A. Since the intake passage 21B is isolated from each other, deterioration of the intake charging efficiency due to the decrease in the intake inertia effect as described above and the accompanying decrease in the engine output, and the decrease in the fuel atomization and atomization action in the engine body It is possible to prevent the deterioration of the combustion characteristics of the engine and improve the engine output characteristics and the combustion characteristics at the same time.

On the other hand, in the high-speed / high-load operation region of the engine that requires high output, the on-off valve 23 is held open, and the first intake passage 21A and the second intake passage 21B are connected to each other via the communication passage 22. To be Therefore, the first intake port that is closed first
When 12A is closed and a compression wave due to the intake inertia is generated in the first intake passage 21A, this compression wave is propagated to the intake air on the second intake passage 21B side through the communication passage 22 and is closed after the second intake passage 21B. In the vicinity of the closing timing of the intake port 12B, the intake air in the second intake passage 21B is forcibly pushed into the working chamber.
That is, the supercharging action of the intake air using the compression wave of the intake air is realized. Therefore, as compared with the case where such a supercharging action does not work, the intake charging efficiency is significantly increased, and the engine output is increased accordingly.

That is, in the intake system of this embodiment, the intake charging efficiency is improved by the supercharging effect of the intake in the high speed and high load operating range of the engine and by the inertia effect of the intake in the other operating range. It is something.

In the above description, an engine of the type in which both the first intake port 12A and the second intake port 12B are opened and closed throughout the entire operating range of the engine is used as the engine, and in this case, the high speed and high load operating range of the engine is used. The open / close valve 23 is used as the intake flow control means for preventing a part of the intake air on the first intake passage 21A side from being introduced into the working chamber from the second intake port 12B side in the operating regions other than the above. The present invention is not limited to this. For example, the second intake port 12B can be opened / closed only in the high speed / high load operation region, and the second intake port 12B can be opened / closed in other operation regions.
It can also be applied to an engine equipped with an appropriate port control means (for example, a valve selector) that acts so as to keep 12B closed. In this case, the port control means functions as the above-mentioned intake flow control means, The same effect as that of the above-described embodiment can be obtained.

Further, the present invention is of course applicable not only to a reciprocating engine that opens and closes an intake port with an intake valve, but also to a rotary piston engine that opens and closes the intake port.

Further, the on-off valve 23 may be opened in the high speed operation area or the high load operation area.

[Brief description of drawings]

FIG. 1 is a transverse cross-sectional view of an essential part of an engine equipped with an intake device according to an embodiment of the present invention, and FIG. 2 is an operational characteristic diagram of a first intake port and a second intake port of the engine shown in FIG. FIG. 3 is an operating region diagram of the on-off valve in the engine shown in FIG. 1 ... Engine body 2 ... Intake manifold 3 ... Exhaust manifold 4 ... Surge tank 11 ... Cylinder 12A ... First intake port (first closed intake port) 12B ... Second intake port (rear closed intake port) 21A, 21B …… Intake passage 22 …… Communication passage 23 …… Open / close valve

Claims (1)

[Claims] 1. A single cylinder is provided with a first-closed intake port and a second-closed intake port whose closing timings are different from each other, and mutually independent intake passages communicating with the plurality of intake ports. In each of the high-speed operation region, the high-load operation region, and the high-speed high-load operation region of the engine, the above-mentioned first-closed intake air is introduced between the closing timings of the first-closed intake port and the second-closed intake port. A communication passage communicating between the plurality of intake passages is formed at a position where the compression wave of the intake air generated by the closing operation of the port can be propagated to the intake air on the side of the post-closing intake port, and the communication passage further includes: In the operating region of the engine excluding the operating region, the intake air on the side of the first closed intake port is sucked into the working chamber from the rear closed intake port through the communication passage. An intake system for an engine, wherein a suitable air flow control means for as action is provided to prevent the that.