JP2502621B2 - Engine intake system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for a multi-cylinder engine, and more particularly,
The present invention relates to an intake passage in which an inertial supercharging phenomenon of intake air is generated to perform intake supercharging.

(Prior Art) Conventionally, there have been known various ones in which the filling efficiency is increased by a dynamic effect of intake air taken into a combustion chamber in a cylinder of an engine to increase the output torque of the engine. As an example thereof, for example, in the one disclosed in Japanese Patent Laid-Open No. 61-116019, in a multi-cylinder engine, in the intake passage communicated with the intake port of each cylinder from the surge tank,
The communication passages communicating with each other are branched and connected, and an opening / closing valve is provided in the connection portion of the communication passages. For example, in the low speed rotation range of the engine, the opening / closing valve is closed and the intake stroke occurs in each cylinder. By propagating the negative pressure wave of intake air to the upstream side of the intake passage, reflecting and inverting it to the positive pressure wave in the surge tank, and returning the positive pressure wave to the downstream side to act at the end of the intake stroke of the same cylinder. , While increasing the intake pressure at the end of the intake stroke and inertially supercharging the intake air, in the high speed rotation range of the engine, the on-off valve is opened and the negative pressure wave toward the intake passage upstream side in the intake stroke is increased by the surge. Reflection and inversion at the branch connection part with the connecting path on the downstream side of the tank,
In addition, the positive pressure wave obtained at the end of the intake stroke of the other cylinder is acted on at the end of the intake stroke through the communication passage, so that the combined effect of two types of positive pressure waves due to these inertial effect and resonance effect is obtained. By increasing the intake pressure at the end of the intake stroke to supercharge the engine, a good intake supercharging effect is exerted over a wide engine speed range from low speed to high speed, and its output is improved. It is suggested to.

(Problems to be solved by the invention) However, in the proposal, pressure propagation that reverses the negative pressure wave generated in the intake stroke of the cylinder to the positive pressure wave and returns to the end of the intake stroke of the same cylinder, Pressure propagation, in which the positive pressure wave obtained at the end of the intake stroke of each cylinder acts on the end of the intake stroke of another cylinder via the communication passage, is performed in the same intake passage. For this reason, there is a possibility that the original intake supercharging effect may be impaired due to mutual interference of the pressure propagations, and there is room for further improvement.

The present invention has been made in view of the above points, and an object thereof is, as described above, to reverse a negative pressure wave of intake air to a positive pressure wave and return it to the end of the intake stroke of the same cylinder, and Measures are taken to prevent interference between the positive pressure wave in the cylinder and the pressure propagation that acts at the end of the intake stroke of other cylinders, and the intake inertia supercharging effect and the pressure reversal part that require the pressure reversal part are set. It is to ensure that the effect of resonance supercharging between cylinders that is not required can be exhibited more reliably.

(Means for Solving the Problems) In order to achieve this object, the solution means of the present invention divides the intake passage downstream of the surge tank into two types of intake passages, a first and a second type, one of which is provided for each cylinder. The passage for exclusive use of resonance supercharging that causes the positive pressure wave obtained at the end of the intake stroke of to act on the end of the intake stroke of other cylinders.

That is, specifically, the present invention is premised on an intake system for a multi-cylinder engine having an intake passage extending from a surge tank and connected to an intake port of each cylinder of the engine.

The intake passage is composed of first and second intake passages, and the downstream end of the first intake passage is connected to the intake port and the upstream end thereof is connected to the surge tank.

On the other hand, the downstream end of the second intake passage is connected to the intake port, and the upstream ends of the second intake passage are assembled at predetermined equal intervals in a cylinder group in an intake stroke.

(Operation) With the above configuration, in the present invention, the pressure propagation returning to the end of the intake stroke of the same cylinder after the negative pressure wave generated in the intake stroke of each cylinder is inverted into the positive pressure wave with the operation of the engine It is performed in the first intake passage using the surge tank as a pressure reversal unit.

On the other hand, pressure propagation in which the positive pressure wave obtained at the end of the intake stroke of each cylinder acts at the end of the intake stroke of the other cylinder is performed in the second intake passage separate from the first intake passage.

In this way, the pressure propagation for the inertial supercharging of the intake air by the pressure reversing unit and the pressure propagation for the inter-cylinder resonance supercharging that does not require the pressure reversing unit are performed in different intake passages, so that these pressure propagation The original intake supercharging effect is not impaired by the interference of, and therefore the intake charge amount of the engine can be effectively increased.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows the overall construction of an embodiment of the present invention, in which 1 is a fuel injection type in-line 4-cylinder engine having four cylinders 2a to 2d arranged in series. 2a
The ignition order of ~ 2d is 1st cylinder 2a, 3rd cylinder 2c, 4th cylinder 2d
And the order of the second cylinder 2b is set. Each cylinder above
2a to 2d have two first and second intake ports 3 and 4 and one exhaust port (not shown). Reference numeral 5 is an intake passage for supplying intake air into each of the cylinders 2a to 2d, and the intake passage 5 includes an intake supply passage 7 formed in an intake pipe 6,
The surge tank 8 is connected to a downstream end of the intake air supply passage 7.
A collective intake passage 9 formed inside, and an independent intake passage 1 connected to each cylinder 2a to 2d from the collective intake passage 9 and formed in an intake manifold 10 as an intake passage in the present invention.
., And the upstream end of the intake air supply passage 7 is connected to an air cleaner 12. An air flow meter 13 for measuring the amount of intake air is provided in the intake supply passage 7.
And the throttle valve 14 on the downstream side of the air flow meter 13.
And are arranged.

Further, as a feature of the present invention, the independent intake passages 11 extending from the surge tank 8 and connected to the intake ports 3 and 4 of the cylinders 2a to 2d of the engine 1 are the first and second intake passages 15. , 16 and both of the intake passages 15, 16 are in communication with each other at their downstream end portions. The downstream end of the first intake passage 15 is connected to the first intake port 3 and the upstream end is connected to the surge tank 8. The effective length L ₁ of each first intake passage 15 is shown in FIG. In the low speed rotation range of the engine 1, the cylinders 2a to 2d (first cylinder 2a in the figure
The negative pressure wave of the intake air generated in the intake stroke propagates to the upstream end of the intake passage 15 and is reflected and inverted by the surge tank 8 into the positive pressure wave. It is set so as to correspond to the pressure wave reciprocating time Δto before returning to and acting on the same cylinder 2a to 2d at the end of the intake stroke.

On the other hand, the downstream end of the second intake passage 16 is connected to the second intake port 4, and the upstream end thereof has an intake stroke at equal crank angle intervals of, for example, 180 ° (in this case, a cylinder group). Are assembled together in all cylinders 2a-2d). Then, two second intake passages 16 that connect the cylinders 2a to 2d (for example, the first cylinder 2a and the third cylinder 2c) that have intake strokes at equal intervals of 180 ° with the crank angle of the engine 1, As shown in the figure, the effective length L _{2 of} 16 is, for example, a positive pressure wave obtained at the end of the intake stroke of the first cylinder 2a in the high-speed rotation range of the engine 1 and the two second intake passages 16 described above. , 1
It is set so as to correspond to the pressure wave propagation time Δt ₁ through 6 through the action at the end of the intake stroke of the second cylinder 2c.

Further, an opening / closing valve 17 for opening / closing the second intake passage 16 is disposed at the downstream end of each of the second intake passages 16, and these four opening / closing valves 17, 17, ... Are shown in FIG. As shown in (b), the engine 1 is opened and closed in synchronization with each other in accordance with the engine speed so as to open in the low speed rotation range of the engine 1. In FIG. 1, reference numeral 18 is an injector for injecting and supplying fuel to the first intake passage 15 in each of the independent intake passages 11.

Therefore, in the above embodiment, the on-off valves 17, 17, ... Are closed all at once in the low speed rotation range of the engine 1. By closing each of the on-off valves 17, as shown in the upper part of FIG. 3, the negative pressure wave of the intake air generated in the intake stroke of each cylinder 2a to 2d is generated in the first intake passage 15 in the independent intake passage 11. It propagates to the upstream side and is reflected and inverted by the surge tank 8 into a positive pressure wave,
The positive pressure wave returns to the downstream side and enters the inertia supercharging state of intake air that acts at the end of the intake stroke of the same cylinder 2a to 2d. Therefore, the combined pressure wave of the negative pressure wave and the positive pressure wave due to the inversion becomes the maximum pressure at the end of the intake stroke of the cylinders 2a to 2d as shown by the broken line in FIG. The amount of intake air is increased by the pushing action by the engine, and a good inertia supercharging effect of the intake air can be obtained. As shown by the solid line in FIG. 2 (a), the output torque of the engine 1 in the low speed rotation range is increased. Can be increased.

Then, when the engine speed increases and enters the high speed rotation range, the on-off valves 17 are opened. Since the second intake passage 16 is opened as the opening / closing valve 17 is opened, the cylinders 2a
The positive pressure wave (maximum pressure) at the end of the intake stroke of the cylinders 2a to 2d due to the combination of the negative pressure wave and the positive pressure wave in the first intake port 3 of (Shown)
Cylinders 2a to 2d (first cylinder 2a in the figure) from the intake port 3 to the next intake stroke cylinders 2a to 2d (third cylinder 2c)
Of the positive pressure wave propagated through the two second intake passages 16, 16 corresponding to each of the first intake ports 3 of FIG. And its cylinder
The positive pressure wave obtained by the inertia supercharging effect in 2a to 2d is combined to form a higher positive pressure wave, and the pushing action due to the increase of the intake pressure increases the filling amount of the intake air. A good resonance supercharging effect can be obtained, and the output torque in the high speed rotation range of the engine 1 can be increased as shown by the chain line in FIG. That is, as described above, the output torque can be increased over a wide rotation range of the engine 1 from low speed to high speed simply by opening / closing each open / close valve 17 according to the engine speed. In FIG. 2 (a), the characteristic indicated by the broken line is the characteristic in the standard state without the inertia supercharging effect and the resonance supercharging effect of the intake air as described above.

In this case, in the high speed rotation range of the engine 1, the pressure propagation for the inertia supercharging of the intake air by the surge tank 8 is the first.
Of the first intake passage 15 and the second intake passage 16 different from the first intake passage 15 described above. Are prevented from interfering with each other, and the original supercharging effect is not impaired, so that the intake charge amount of the engine 1 can be effectively increased.

The present invention is not limited to the above embodiment,
Various other embodiments are included. For example, FIG. 4 shows an example thereof, and in the above embodiment, the second intake passage 16 is arranged substantially parallel to the side of the first intake passage 15, while in this embodiment, The intake passage 16 'is connected to the intake manifold 10'.
It is integrally formed in the lower side of the first intake passage 15 ', and the downstream end of the second intake passage 16' is formed together with the first intake passage 15 'in one intake port 3 of each cylinder 2a-2d. It is connected to the ‘ Even in this case, it is possible to obtain the same effects as those of the above embodiment.

Further, in the above embodiment, the on-off valve 17 provided in each of the second intake passages 16 is selectively opened and closed according to the engine speed. However, each of the on-off valves 17 is changed in the engine speed. The passage diameter of the second intake passage 16 may be variably controlled by opening and closing in proportion to the above. In this case, the smaller the passage diameter of the intake passage 16 is, the larger the propagation resistance of the pressure wave becomes, and the longer it takes for the propagation of the pressure wave. It is also possible to do so.

Further, it goes without saying that the present invention can be applied to a multi-cylinder engine other than the in-line 4-cylinder engine.

(Effect of the Invention) As described above, according to the present invention, the intake passage from the surge tank to each cylinder is divided into two types of intake passages,
One of them is a passage dedicated to resonance supercharging that causes a positive pressure wave obtained at the end of the intake stroke of each cylinder to act at the end of the intake stroke of other cylinders, so that the inertial supercharging of intake air by the pressure reversal unit is increased. And pressure propagation for inter-cylinder resonance supercharging that does not require a pressure reversal part are performed in different intake passages, and the original intake supercharging effect due to mutual interference of these pressure propagations is diluted. It is possible to effectively suppress the increase in the intake air charge amount of the engine.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a schematic plan view showing the entire structure thereof, FIG. 2 is a characteristic diagram showing characteristics of engine output change with opening / closing of an on-off valve, and FIG. It is explanatory drawing which shows the fluctuation characteristic of the intake pressure near a port. FIG. 4 is a schematic side view showing another embodiment. 1 ... Engine, 2a-2d ... Cylinder, 3,3 ', 4 ... Intake port, 8 ... Surge tank, 11 ... Independent intake passage, 15,1
5 '... first intake passage, 16,16' ... second intake passage,
17 …… Open / close valve.

Claims (1)

(57) [Claims] 1. An intake system for a multi-cylinder engine having an intake passage extending from a surge tank and connected to an intake port of each cylinder of the engine, wherein the intake passage has a downstream end in an intake port and an upstream end. A first intake passage connected to the surge tank and a downstream end connected to an intake port,
An intake device for an engine, wherein an upstream end is configured with a second intake passage that is assembled with each other in a cylinder group having an intake stroke at equal intervals.