JPH01190917A - Intake device for engine - Google Patents

Abstract

PURPOSE:To improve the engine output by a supercharge action according to the proper vibration of an intake system by installing a plurality of intake collection parts which communicate to a plurality of cylinders and making different each characteristic frequency of a plurality of intake collection parts which communicate to the cylinders. CONSTITUTION:The first port 3 of each cylinder 2 of the first and second banks 1A and 1B is collected for the mutual communication by the intake collecting parts 13a and 13b of the first branched passages 7a and 7b. Similarly, the second intake ports 4 are collected for the mutual communication by the intake collecting parts 14a and 14b of the second branched passages 8a and 8b. Each length of the independent parts 15a and 15b is formed longer than each length of the independent parts 16a and 16b, and each characteristic frequency is made different. Therefore, the engine output can be improved in a wide range by the supercharge action according to the proper vibration of an intake system.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine that performs supercharging by utilizing the natural vibration of the intake system.

(Prior Art) Conventionally, there has been an intake system that utilizes the pressure fluctuations that occur in the intake passage between the cylinders of a multi-cylinder engine to increase the pressure at the intake port in the latter half of the intake stroke to obtain a supercharging effect. Various proposals have been made. In addition, in this intake system, the supercharging effect can be obtained in a group of cylinders with little overlap in the intake stroke, and the natural frequency corresponding to the shape of the intake passage and the engine rotation speed, that is, the excitation frequency of the piston are aligned. In order to obtain a supercharging effect over a wider range, it is necessary to set multiple resonance points. A valve, a control valve for changing the volume of the volume portion, and the like are provided (for example, see Japanese Utility Model Publication No. 198324/1983).

(Problem to be Solved by the Invention) However, in the above-mentioned intake system, since a variable mechanism such as a control valve is installed to obtain multiple resonance points, the operating state such as engine speed etc. This requires a control mechanism to drive the variable mechanism in response to changes in the variable temperature.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, it is an object of the present invention to provide an engine intake system that can obtain a plurality of resonance points without using a variable mechanism such as a control valve.

(Means for Solving the Problems) In order to achieve the above object, an intake system of the present invention includes a plurality of intake collecting portions each communicating with at least two or more intake passages communicating with each cylinder of a multi-cylinder engine, The intake passage on the upstream side of the intake air collecting portion is made independent at least up to the pressure inversion portion, and at least two or more intake air collecting portions are arranged to communicate with each cylinder, and the intake air collecting portion communicating with each cylinder and its intake air The structure is such that a plurality of resonance points are obtained by varying the natural frequencies up to the pressure inversion section on the upstream side.

(Function) In the engine intake system as described above, each cylinder is arranged so that at least two or more intake collecting parts communicate with each other, and the natural frequency between the intake collecting part communicating with each cylinder and the pressure reversal part is adjusted. Each one is different, and configured to obtain multiple resonance points, ensuring a supercharging effect at each resonance point, and a supercharging effect that corresponds to the natural vibration of the intake system over a wide range without using a variable mechanism. The aim is to improve engine output by obtaining

(Example) Hereinafter, each embodiment of the present invention will be described along with the drawings.

Embodiment 1 This embodiment is shown in FIG. 1 and is an example of a V-type six-cylinder engine.

The engine body 1 has a first bank I arranged with three cylinders each.
A and a second bank IB, and two intake ports, a first intake port 3 and a second intake port 4, are open to each cylinder 2.

The intake passage 5 that supplies intake air to each cylinder 2 of both banks IA and IB is branched into a first intake passage 7 and a second intake passage 8 at the downstream side of the surge tank 6. The first intake passage is connected to banks IA and IB on both sides from the pressure inversion part 1°.
The first branch passages 7a and 7b are connected to the first intake ports 3 of the three cylinders 2 of the banks IA and 1B on both sides, respectively. Also, the second
The intake passage 8 extends from the pressure inversion part 12 on the downstream side of the control valve 11 to second branch passages 8a and 8 for banks IA and IB on both sides.
b, and each branch passage 8a, 8b connects the bank IA on both sides.
, IB are in communication with the second intake boats 4 of the three cylinders 2, respectively.

That is, the first intake ports 3 of each cylinder 2 of the first and second banks IA, IB are connected to each other by the intake collecting portions 13a, 13b of the first branch passages 7a, 7b, and are similarly connected to the second intake boat. 4 are connected to each other by the second branch passages 8a and sb and the intake collecting portions 14a and 14b. First branch passages 7a, 7b and second branch passage 8a on both sides.

Reference numeral 8b indicates the respective intake air gathering portions 13a and 13b.

The intake passages on the upstream side of the intake air of 14a and 14b are independent parts 15a, 15b, 16. a, 16b and are connected to the pressure reversing parts 1o, 12, respectively, and due to the above-mentioned intake passage structure, each cylinder 2 has two intake collecting parts 13a, 14a or 13b, 14b.
are configured so that they communicate.

The pressure reversal section 10.12 has banks IA and IB on both sides.
Due to the phase difference in the intake stroke at this point, pressure fluctuations with opposite phases occur, and the pressure wave acts to reverse and return at this portion.

And, the intake collecting portion 13a of the first branch passages 7a, 7b,
Independent parts 15a, 15b from 13b to pressure reversal part 1o
The length of the intake collecting portion 14a of the second branch passages 8a and 8b is
, 14b to the pressure reversing part 12, independent parts 16a, 16
It is formed to be longer than the length of b, and is provided so that each natural frequency is different. In this case, the independent part 15a
, 15b, the first intake passage 7 having a longer length has a lower natural frequency and resonates in the low speed region of the engine rotation speed, and the second intake passage 8 has a higher natural frequency and resonates in the high speed side, causing switching. The basic structure is set to obtain a supercharging effect at each resonance point without any control.

The control valve 11 installed in the second intake passage 8 is operated to open and close in a rotation range lower than the resonance point of the first intake passage 7, and when the control valve 11 is closed, the second intake passage 8 is opened and closed.
The intake air gathering portions 14g and 14b of the intake passage 8 constitute a closed volume portion that communicates with each cylinder 2, and due to the increase in the volume, the natural frequency becomes lower speed side, and the control valve 11 increases in response to engine rotational fluctuations. By opening and closing, the resonance point is shifted and a supercharging effect can be obtained over a wide range.

Further, as shown in FIG. 2, if the valve timing (2) of the second intake boat 4 is set to close earlier than the valve timing I of the first intake boat 3, the first and second intake passages 7, 8 independent parts 15a, 15b, 16a
, close the respective intake boats 3 and 4 when the pressure is high corresponding to the transmission time of the pressure wave corresponding to the length of 16b,
This allows a sufficient resonance supercharging effect to be obtained.

According to this embodiment, each cylinder 2 has two cylinders with different natural frequencies.
four intake air collecting parts 13a, 13b, 14a.

14b, the resonance excess is caused in multiple regions so that the engine output increases at the resonance points R1*R2 corresponding to each natural frequency, as shown in FIG. The effect of supplying energy can be obtained without any switching operation. Also, at low speed, the control valve 11
By closing the valves, a supercharging effect in the low speed range can be obtained, and by setting the valve timing, the supercharging effect is ensured at the respective resonance points R1 and R2.

Embodiment 2 This embodiment is shown in FIG. 4, and shows an example of an in-line three-cylinder engine.

Two intake ports, a first and second intake boat 3.4, are opened in each cylinder 2 of the engine main body 21, and the first intake port 3 of each cylinder 2 is connected to the intake port 22 of the first intake passage 22.
Similarly, the second intake boats 4 are connected to each other by an intake collecting portion 23a of the second intake passage 23. The first intake passage 22 is connected to the surge tank 22 from the intake air collecting section 22a through a long independent section 22b.
1; and the second intake passage 23 is connected from the intake collecting part 23a to the pressure reversing part 23C for the surge tank 24 via a short independent part 23b, thereby forming an intake passage 25.

Note that the pressure reversing portion 22 c r 23 c in this example is such that pressure waves are inverted and reflected at the open end with respect to the surge tank 24 . The reversing portions 22c and 23c may be constructed of other components having a predetermined volume, such as an air cleaner.

Due to the above-mentioned intake passage structure, each cylinder 2 has two intake collecting portions 22a having different natural frequencies.

23a are configured to communicate with each other. Note that, as in the previous example, a control valve (not shown) that closes at low speeds may be interposed in the second intake passage 23 having a high natural frequency. Further, the valve timing at which the first intake port 3 closes may be set to close later than the second intake port 4 in accordance with its natural frequency. Furthermore, even if the number of cylinders is increased, such as in an in-line four-cylinder engine, it is sufficient to configure the engine in the same manner as the three-cylinder engine.

In this example as well, the first intake passage 22 with the longer length of the independent portion 22b has a lower natural frequency and resonates in the low engine speed region, while the second intake passage 23 has a higher natural frequency and resonates on the high speed side. The basic structure allows the supercharging effect to be obtained at each resonance point without any switching control.

Embodiment 3 This embodiment is shown in FIG. 5 and shows an example of a single-intake boat with an in-line three-cylinder engine.

A single intake boat 32 is provided for each cylinder 2 of the engine body 31.
is opened, and the first intake passage 22 and second intake passage 23 similar to the previous example are connected together to the intake boat 32 of each cylinder 22, and each cylinder 2 is connected to the intake boat 32 of each cylinder 22.
a and the intake air collecting portion 23a of the second intake passage 23. The first intake passage 22 is connected to an intake collecting section 22.
The second branch passage 23 is connected from the intake gathering part 23a to the pressure reversal part 23c for the surge tank 24 via the short independent part 23b from the intake collecting part 23a, and is connected to the pressure reversal part 23c for the surge tank 24 through the long independent part 22b. A passage 33 is configured. Due to this intake passage structure, each cylinder 2 is communicated with two intake collecting portions 22a and 23a having different natural frequencies.

Further, the opening/closing timing of the intake port 32 is made variable by a known variable mechanism, and the intake port closing timing is changed according to the characteristics shown in FIG. First, the resonance point R1 of the first intake passage 22 occurs on the low speed side and the resonance point R2 of the second intake passage 23 occurs on the high speed side due to the intake passage structure with respect to the engine rotation speed. The closing timing is changed to be delayed as the pressure increases, and the closing timing is adjusted so that the intake port 32 closes when the pressure is highest.

Note that when transitioning from the zone of the first resonance point R1 to the zone of the second resonance point R2, the change is made in steps, but this may be changed continuously.
``The change characteristics (inclination) of the closing timing with respect to rotational fluctuations may be changed depending on the resonance zone, and these are appropriately set in accordance with the intake passage structure.

In this embodiment, each cylinder 2 has an intake passage structure in which it communicates with two intake collecting parts 22a and 23a having different natural frequencies through a common intake port 32, so that each cylinder 2 can reach its resonance point without performing switching control. In addition to obtaining a supercharging effect,
By changing the closing timing of the intake port 32, a high supercharging effect can be obtained over a wide range.

In addition, in the above-mentioned Examples 1 and 2, the above-mentioned Example 3
A variable valve timing mechanism may be provided as shown in the figure below, and the closing timing of the intake port may be changed to become later as the engine speed increases near each resonance point.

Furthermore, in each of the above embodiments, the natural frequencies are made to differ by changing the length of the intake passage in the independent section, but it is also possible to configure an intake system with a different natural frequency by changing the passage diameter, etc. You may also do so.

(Effects of the Invention) According to the present invention as described above, a plurality of intake collecting portions communicating with a plurality of cylinders are provided, at least two or more intake collecting portions are arranged to communicate with each cylinder, and each cylinder is provided with a plurality of intake collecting portions communicating with each other. By making the natural frequencies of the plurality of connected intake air collection parts different to obtain a plurality of resonance points, it is possible to obtain the supercharging effect at each resonance point without using a variable mechanism. It is possible to improve engine output over a wide range by supercharging the natural vibration of the intake system.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an engine intake system according to the first embodiment of the present invention, Fig. 2 is a characteristic diagram showing an example of valve timing settings, and Fig. 3 is an output performance due to the resonance effect on engine speed. FIG. 4 is a schematic configuration diagram of the engine intake system in the second embodiment, FIG. 5 is a schematic configuration diagram of the engine intake system in the third embodiment, and FIG. 6 is a schematic diagram of the engine intake system in the third embodiment. FIG. 3 is a characteristic diagram showing variable characteristics of intake valve closing timing in an example. 1.21.31...Engine body, 2...
...Cylinder, 3.4.32...Intake port, 5,
25.33...Intake passage, 7,22...
・First intake passage, 8, 23... Second intake passage,
10, 12, 22c, 23c...---Pressure reversal section, 13a, 13b, 14a, 114 b, 22 a
, 23 a... Intake gathering part. Fig. 2 Fig. 3 Ethic ω-electronic arm

Claims (1)

[Claims] (1) In an engine equipped with a plurality of cylinders, a plurality of intake collecting parts each communicating with at least two or more of the intake passages communicating with the cylinders are provided, and the intake passage on the upstream side of the collecting part is connected to at least a pressure reversing part. At least two or more intake collecting parts are arranged so as to communicate with each cylinder, and the natural frequencies of the intake collecting part communicating with each cylinder and the pressure reversal part on the upstream side of the intake air are made different. An engine intake system characterized by: