JPH0819851B2 - Multi-cylinder engine intake system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake device for a multi-cylinder engine in which a surge tank is provided in an intake passage.

[Prior Art] It is well known that in a multi-cylinder engine, pressure wave supercharging is performed by utilizing the inertial effect or resonance effect of the intake system to improve the charging efficiency.

Here, the pressure wave supercharging due to the inertia effect means that a volume portion is provided in the upstream portion of the independent intake passage of each cylinder, and the negative pressure wave generated in the intake port when the intake valve of each cylinder is opened causes Reciprocating in the independent intake passage between the
At this time, the phenomenon in which the negative pressure wave is inverted into the positive pressure wave in the volume portion is used to push the intake air into the combustion chamber by this positive pressure wave, and this effect depends on the pipe length of the independent intake passage. Due to restrictions, it has the characteristic of becoming higher at relatively high rotation speeds.

On the other hand, the pressure wave supercharging due to the resonance effect means that a cylinder group composed of cylinders whose ignition timings are not continuous is formed, and the independent intake passages of the cylinders belonging to this cylinder are gathered in one common intake passage in the upstream portion. , A volume portion is provided at a predetermined position of this common intake passage, and a pressure wave of each cylinder that propagates back and forth between each cylinder and the volume portion is resonated, and is larger than the pressure vibration generated in each individual cylinder. A steady pressure wave having an amplitude and a natural frequency determined by the dimensions of the volume and the intake passage is generated so that a larger supercharging effect can be obtained. Since the wave propagation path length is longer than in the case of the inertial effect described above, it has a characteristic that the effect is exhibited in a relatively low rotation range.

By the way, in such a pressure wave supercharging system by the resonance effect, attention is paid to the fact that the phases of the pressure waves in the intake system between the two cylinder groups are opposite to each other. By providing a communicating portion that communicates the passages, and utilizing the phenomenon that the pressure in the communicating portion is uniformly maintained by the mutual interference action of the pressure waves of both cylinder groups, the communicating portion has the same function as the volume portion. It has been proposed to make the intake system simpler. (See, for example, Japanese Utility Model Publication No. 56-120315 and Japanese Utility Model Publication No. 58-175121).

Focusing on the two characteristics of pressure wave supercharging as described above, pressure wave supercharging is performed by the resonance effect in a predetermined low rotation range of the engine, while pressure waves are generated by the inertia effect in a predetermined high rotation range. It has been proposed that supercharging is performed to improve the supercharging effect in the entire rotation range. As one of the methods, for example, as shown in FIG. 5, a surge tank 31 having a predetermined volume is provided in the intake system, and both side surfaces extending in the longitudinal direction of the surge tank 31 are respectively ignited. The independent intake passages 32 of the cylinder group composed of cylinders which are not consecutive are connected to each other, and the communication portion 33 extending in the arrangement direction of the independent intake passages 32 is provided at the center of the surge tank 31. An on-off valve 36 that connects or disconnects the two space portions 34 and 35, which are respectively connected to one cylinder group, is provided, and when the engine speed is low, the on-off valve 36 is closed to establish a communication passage.
The pressure wave is supercharged by the resonance effect with 33 as the pressure reversal part, while the open / close valve 36 is opened at high speed to surge tank.
It has been proposed that 31 acts as a single volume to perform pressure wave supercharging by the inertial effect (see, for example, Japanese Patent Application No. 60-183530).

However, in this conventional one, even if the on-off valve is opened, the space portions on both cylinder group sides in the surge tank communicate with each other only through the narrow communication portion of the portion provided with the on-off valve. The surge tank does not completely function as a volume portion having a sufficient volume, and there is a problem in that the efficiency of the inertia effect at the time of high rotation decreases.

[Object of the Invention] The present invention has been made in view of the above conventional problems, and a surge tank is provided in the intake system to perform both pressure wave supercharging due to the inertia effect and pressure wave supercharging due to the resonance effect. It is an object of the present invention to provide an intake system for a multi-cylinder engine in which high supercharging efficiency is obtained and engine output is improved in the entire rotation range of the engine in the multi-cylinder engine.

In order to achieve the above object, the present invention has an intake device for a multi-cylinder engine in which a surge tank having a predetermined volume is provided in an intake passage, and each side wall extending in the longitudinal direction of the surge tank is provided with a side wall. While connecting the independent intake passages of the cylinders whose ignition orders are not continuous to each other, a plurality of on-off valves extending in the longitudinal direction of the surge tank are provided in the surge tank at predetermined intervals in a direction intersecting the longitudinal direction. When the plurality of on-off valves are closed, a communication passage is formed between adjacent ones of the on-off valves to connect the space on one side wall side and the space on the other side wall side, and the plurality of on-off valves are opened. Provided is an intake system for a multi-cylinder engine, characterized in that the on-off valve is arranged so as to obtain a sufficient surge tank capacity when it is opened.

[Effect of the Invention] According to the present invention, if each on-off valve is closed in a predetermined low rotation range, a communication passage extending between the adjacent on-off valves in the surge tank over substantially the entire length thereof in the longitudinal direction of the surge tank. Is formed, and this communication passage functions as a resonance tube having a resonance effect having a sufficient length and a pressure reversal portion, so that a high resonance effect can be obtained with a compact structure utilizing a limited space.

On the other hand, if each on-off valve is opened in a predetermined high rotation range, there is no substantial obstruction to the flow of intake air or the propagation of pressure waves in the direction intersecting the longitudinal direction of the surge tank, and the surge tank has a sufficient volume. It can function as a single volume with. In this case, the negative pressure wave propagating upstream in each independent intake passage is almost completely pressure-reversed in the surge tank and returns to each cylinder as a strong positive pressure wave. Efficiency or engine power is increased.

[Examples] Examples of the present invention will be specifically described below.

FIG. 1 and FIG. 2 are a partial sectional plan view and a partial sectional elevation view of an intake device around a surge tank showing an embodiment of the present invention.

As shown in these drawings, two side walls 2 extending in the longitudinal direction of a long and slender hollow surge tank 1 disposed in the upper portion of a 6-cylinder reciprocating engine (not shown).
Of the p and 2q, the first side wall 2p has a side end 1t (hereinafter referred to as a rear end 1t) from the intake inflow side end 1s (hereinafter referred to as a front end 1s) side of the surge tank 1 to the other side end 1t. In the order of, the first, third, and fifth cylinders whose ignition order is not continuous (not shown,
Hereinafter, these are referred to as the first cylinder group)
The third and fifth independent intake passages 3a, 3c, 3e (hereinafter referred to as the first independent intake passage group 3p) are connected, while the second side wall 2q extends from the front end 1s side toward the rear end 1t side. The second, fourth, and sixth independent intake passages 3b, 3d communicating with the second, fourth, and sixth cylinders (not shown, but hereinafter referred to as the second cylinder group) whose ignition order is not continuous. , 3f (hereinafter referred to as the second independent intake passage group 3q)
Is connected.

The surge tank 1 extends through the rear wall 2t of the surge tank 1 at a position closer to the center in the direction orthogonal to the longitudinal direction (hereinafter referred to as the transverse direction) in the space inside the surge tank 1. A first on-off valve 6 mounted on a first valve shaft 5 extending in the direction of most of its entire length.
With respect to the first valve shaft 5, the second side wall 2q side is kept at a predetermined distance from the first valve shaft 5, and the rear wall 2t of the surge tank 1 is penetrated. Further, the top wall 2u and the bottom wall 2w of the surge tank 1 A second on-off valve attached to a second valve shaft 8 that penetrates a part of the rear partition wall 7 connected to the longitudinal direction thereof and extends in the longitudinal direction of the surge tank 1 over most of its entire length. 9 and are provided. Since the rear partition wall 7 is not formed in front of the front end portion 7h, the space inside the surge tank 1 is not partitioned at this portion.

When the first on-off valve 6 is closed as shown in FIGS. 1 and 2, the first on-off valve 6 and the upper wall 2u
And a front partition wall 11 connected to the bottom wall 2w cooperate with each other to partition the space in the surge tank 1 in the transverse direction except for the first communication portion 12 that does not cover the first opening / closing valve 6. In addition,
Since the front partition wall 11 is not formed behind the rear end portion 11h, the space inside the surge tank 1 is not partitioned at this portion. A first chamber 14 that communicates directly with the first independent intake passage group 3p and also communicates with the first common intake passage 13 to which intake air is supplied is defined between these and the first side wall 2p. Similarly, when the second opening / closing valve 9 is closed, the second opening / closing valve 9 and the rear partition wall 7 cooperate with each other so that the space inside the surge tank 1 is not covered by the second opening / closing valve 9. It is partitioned in the transverse direction except the communication portion 15, and the second side wall 2q is directly communicated with the second independent intake passage group 3q, and the second common intake passage 16 is supplied with intake air. A second chamber 17 that communicates is defined.

When the first on-off valve 6 and the second on-off valve 9 are closed, the space defined between them is the first
The communication part 12 communicates with the first chamber 14 and the second communication part 15
In the above, a communication passage 18 is formed which communicates with the second chamber 17 and which is elongated in the longitudinal direction of the surge tank 1.

On the other hand, when the first opening / closing valve 6 and the second opening / closing valve 9 are opened, the one that intercepts the space in the surge tank 1 in the transverse direction is substantially the same in area as the rear partition wall 7 and the front partition wall. Only the partition wall 11 is provided, and the space within the surge tank 1 forms a single volume having substantially the entire volume of the surge tank 1.

The first opening / closing valve 6 and the second opening / closing valve 9 have a link mechanism 21.
The actuator 22 is opened and closed at the same timing via the. However, when both the first opening / closing valve 6 and the second opening / closing valve 9 are opened, as shown in FIG. 3, they interfere with each other. The mounting position of the second valve shaft 8 is set in the vertical direction with an offset of a length d corresponding to the thickness of the first and second on-off valves 6 and 9.

 The operation of this embodiment will be described below.

The engine speed N is a predetermined speed N ₀ as shown in FIG.
In the smaller low speed range, actuator 22
Both the first and second on-off valves 6 and 9 are closed. At this time, as described in detail in the prior art example of the present application, the first cylinder group 3p and the second cylinder group 3q respectively have the communication passage 18 through the mutual interference of the pressure waves of the intake systems of both cylinders 3p and 3q. Pressure wave supercharging is performed by the resonance effect of the pressure equalizing portion, that is, the pressure wave inverting portion. The characteristic of the output (torque) of the engine when the pressure wave supercharging due to the resonance effect is performed is the fourth characteristic.
It becomes like a curve G ₁ in the figure, and reaches a maximum at a predetermined rotation speed smaller than N ₀ , and on the higher rotation side than this, it sharply decreases as the rotation speed increases.

Therefore, in the high speed range where the engine speed N is N ₀ or more,
The actuator 22 opens both the first and second on-off valves 6 and 9 to perform pressure wave supercharging by the inertial effect that is effective in a high rotation range. At this time, since the space inside the surge tank 1 is substantially a single volume as described above, the space inside the surge tank 1 is different in each cylinder as described in the related art. Pressure wave supercharging is performed by the inertial effect of the volume. The characteristic of the engine output when the pressure wave supercharging by the inertial effect is performed is as shown by a curve G _{3 in} FIG. 4, and becomes maximum at a predetermined rotation speed higher than N ₀ . In the present proposal, the space inside the surge tank 1 becomes a volume having a sufficient volume, and the negative pressure wave propagating from each independent intake passage is almost completely inverted to the positive pressure wave, so that the supercharging effect is enhanced. For example, the engine output is significantly improved as compared with the conventional one as shown by the curve G ₂ in FIG.

In this way, according to the present invention, by opening and closing the on-off valve in the surge tank, strong pressure wave supercharging is performed by the resonance effect in the low rotation range and the inertial effect in the high rotation range. The engine output can be improved.

In this embodiment, two on-off valves are provided in the surge tank. However, even if the number of on-off valves is increased to make a plurality of communication passages, the same action and effect as in this embodiment can be obtained. Of course.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are a partial sectional plan view and a partial sectional elevation view of an intake device around a surge tank showing an embodiment of the present invention, respectively. FIG. 3 is a cross-sectional explanatory view taken along the line BB of FIG. FIG. 4 is a diagram showing the characteristic of the output (torque) of the engine according to the present invention with respect to the engine speed. FIG. 5 is an explanatory view showing a conventional surge tank provided internally with a communication passage acting as a pressure equalizing portion for resonance effect. 1 ... surge tank, 3a, 3b, 3c, 3d, 3e, 3f ... first to sixth independent intake passages, 6 ... first opening / closing valve, 9 ... second opening / closing valve, 14 ... first chamber , 17 …… Second room, 18 …… Communication passage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masanori Kotoku, No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) References JP-A-62-41922 (JP, A) Jikkouhei 7- 17783 (JP, Y2)

Claims (1)

[Claims] 1. An intake system for a multi-cylinder engine in which a surge tank having a predetermined volume is provided in an intake passage, and a side wall extending in the longitudinal direction of the surge tank is provided with cylinders whose ignition sequences are not continuous with each other. While connecting the independent intake passages, a plurality of on-off valves extending in the longitudinal direction of the surge tank are provided in the surge tank at a predetermined interval in a direction intersecting the longitudinal direction, and the on-off valves are closed. Occasionally, a communication passage that connects the space on one side wall side and the space on the other side wall side is formed between the adjacent open / close valves, and a sufficient surge tank capacity is obtained when the plurality of open / close valves are opened. An intake device for a multi-cylinder engine, in which the on-off valve is arranged as described above.