JPS61241418A - Suction device for multicylinder engine - Google Patents

Abstract

PURPOSE:To improve the extent of efficiency yet better, by specifying the length and sectional area of a pipe interconnecting surge tanks in each suction pipe all the time, in case of an engine which interlocks these independent suction pipes of two cylinder groups via a throttle valve and improves a degree of charging efficiency by a resonance effect. CONSTITUTION:Two cylinder groups 21 and 22 forming such cylinders as being unadjoined in suction sequence into one group charges air to surge tanks 71 and 72 at each cylinder group via a manifold 9, split passages 81 and 82 and throttle valves 101 and 102, while air charging takes place for each cylinder separately from these surge tanks. An interval between these surge tanks 71 and 72 are interconnected with a resonance pipe to be normally interconnected and an on-off valve 13 to open at high speed. When pipe length of these split passages 81 and 82 is set to l and the pipe diameter to (d) while half length of the resonance pipe 11 to L and the pipe diameter to D, respectively, they are set up so as to satisfy the condition of d/l<1/2D/L<1/2>. With this constitution, if the valve 13 is being closed at low speed, suction air resonates with the resonance pipe 11 being relatively large in diameter whereby it comes to have no relation with the split passage so that there is not influence of these throttle valves 101 and 102.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for a multi-cylinder engine, and more particularly to an intake system for an engine that utilizes the resonance effect of the intake system to increase the amount of intake air.

(Prior art) In recent years, in automobile engines, attempts have been made to improve the intake air filling rate by using dynamic effects such as inertia effects and resonance effects. An example of a device that utilizes this is an engine intake device disclosed in Japanese Utility Model Application Laid-Open No. 59-148425.

As shown in Fig. 3, the six cylinders 11 to 16 in the engine 1 are grouped into two cylinder groups, including those that are not adjacent in the intake order, that is, the first to third cylinders 11 to 13. group and a cylinder group consisting of the fourth to sixth cylinders 14 to 16, and the first to third cylinders 11 to 13 are connected to the first resonance passage 31 via independent passages 21 to 23. , the fourth to sixth cylinders 14 to 16 are connected to the second resonance passage 32 via independent passages 24 to 26, and both resonance passages 31 and 32 are further merged at the upstream end to form a merging passage led from the air cleaner 4. 5. And the above 1. When the intake air in the second resonance passage 31.32 resonates in a predetermined engine rotation range corresponding to its natural frequency, a large positive pressure wave is generated in both the resonance passages 31.32 and in each of the independent passages 21 to 26. This causes the action of pushing intake air into each of the cylinders 11 to 16 at the end of the intake stroke. The intake device disclosed in the above publication is provided with an on-off valve 8 that opens and closes the communication hole 7 formed in the gap 16 that partitions the first and second resonance passages 31 and 32. By changing the natural frequencies of the resonance passages 31 and 32 by opening and closing, resonance effects can be obtained in a plurality of engine rotation ranges.

By the way, in the above-mentioned intake device, the first. Since the throttle valves 91 and 92 are respectively disposed in the second resonance passages 31 and 32, especially when the communication hole 7 in the partition wall 6 is closed by the on-off valve 8, both resonance passages 3
When the positive pressure waves generated by the resonance of the intake air in 1.32 propagate in both passages 31 and 32, they are reflected by the throttle valves 91 and 92, or are absorbed and attenuated, and as a result, each of the above The pushing action of intake air into the cylinders 11 to 16 becomes insufficient, and an effective resonance effect cannot be obtained. In that case, when the positive pressure wave is not attenuated by an obstacle such as a throttle valve, an output torque characteristic as shown by the solid line (A) in Figure 4 is obtained due to the effective resonance effect. When the positive pressure wave is attenuated, the output torque characteristic becomes as shown by the chain line (b) in the same figure, and the output torque decreases especially near the engine speed 01 where the output torque peaks due to the resonance effect. . In addition, to prevent such a situation,
A throttle valve may be provided upstream of the confluence A at the upstream end of both resonance passages 31 and 32, but in this case, the passage length from the throttle valve to each cylinder 11 to 16 becomes long; Therefore, a problem arises in that the responsiveness of adjusting the intake air flow rate to each cylinder 11 to 16 by the throttle valve deteriorates.

(Object of the Invention) The present invention is directed to an engine that improves the intake air filling rate by utilizing the resonance effect in the intake system, and in particular, an engine that uses the resonance effect in the intake system to improve the intake air filling rate. Two intake collecting parts are provided, and two divided passages each having a throttle valve are connected to these two intake collecting parts. In a cylinder engine, a passage that acts as a resonance pipe is newly provided in addition to the two divided passages. As a result, when the two divided passages are used as a resonance pipe, the throttle valve becomes an obstacle and a sufficient resonance effect cannot be obtained, and this prevents the situation where a sufficient resonance effect cannot be obtained. The purpose is to improve filling efficiency.

(Structure of the Invention) In order to achieve the above object, the present invention is characterized by the following structure. That is, two intake collecting parts each communicate with the intake ports of two cylinder groups that are not adjacent in the intake order, and one intake collecting part connected to these two intake collecting parts respectively on the upstream side.
In an intake system for a multi-cylinder engine, which is provided with two divided passages that merge into one another and are each provided with a throttle valve, a resonance pipe is provided that communicates the two intake air collection parts. This resonance tube does not have any obstructive parts inside the tube, and the length and diameter of the resonance tube are 1/2 of the total length of the two divided passages. For length 1 and pipe diameter d, d /√l<D/V""r
It is set to satisfy the condition (I). In this way, if the two divided passages are elongated compared to the resonance tube based on the above formula (I), the resonance effect will mainly occur in the resonance tube, and the above two
No resonance of intake air occurs in the two divided passages.

(Effects of the Invention) As described above, according to the present invention, there are two intake collecting sections provided corresponding to two cylinder groups whose intake orders are not adjacent to each other, and an air intake collecting section provided on the upstream side of these two intake collecting sections. In an intake system for a multi-cylinder engine, the intake system has two divided passages each connected to a throttle pulp and each having a throttle pulp.
A resonance tube is provided which communicates the above two intake air gathering parts and has no obstructing part inside the tube, and the resonance effect is obtained by the resonance tube, so that the resonance effect is obtained by the above-mentioned divided passage. In this case, the resonance effect will not be degraded due to failure of the throttle valve or the like, and the desired resonance effect or intake air filling efficiency improvement effect can be reliably obtained.

(Example) Embodiments of the present invention shown in the drawings will be described below.

In this embodiment, the intake system according to the present invention is applied to a type 2 engine.

As shown in FIG. 1, the V-type engine 1 has a first bank 21
and a second bank 22, and the first to third cylinders 31 to 33 formed in the first bank 21 and the fourth to sixth cylinders 34 to 36 formed in the second bank 22 have an intake order, respectively. They are configured so that they are not adjacent to each other. That is, the intake order is, for example, first cylinder 31 → fourth cylinder 34 → second cylinder 32 → fifth cylinder 35 → third cylinder 33 → sixth cylinder 36,
In other words, the two banks of 21.220 cylinders perform intake strokes alternately without overlapping.

On the other hand, the intake device 4 that supplies intake air to each of the cylinders 31 to 36 has independent intake passages 61 to 66 whose downstream ends are connected to the intake boats 51 to 56 of the air intakes 113t to 36, respectively, and a first
A first surge tank 71 to which the upstream ends of the independent intake passages 61 to 63 in the bank 21 are connected, a second surge tank 72 to which the upstream ends of the independent intake passages 64 to 66 in the second bank 22 are connected, and both surge tanks. 71 and 72 and whose upstream ends are merged. A second divided passage 81, 82 and a first divided passage 81, 82 leading from an air cleaner (not shown). Merging part (branching part) of second divided passage 81.82
and a merging passage 9 connected to the first. The second divided passages 81 and 82 each have a first throttle valve 1 and a second throttle valve 1.
01.102 is provided.

However, the above 1. On the downstream side of the second surge tank 71.72, a communication passage 11 is provided that communicates both tanks 71.72. This communication path 11 has no obstructing portion within the path, and the first. The length L and diameter of each of the second passages 111 and 112 are the same as those of the first passage. Length 1 of the second divided passage 81.82
and the pipe diameter d are set so as to satisfy the conditions of d/Anr and the D/C port. Here, the first. The second passage 111°112 and the first passage. The second divided passage 81.82 has a natural frequency corresponding to the foil pipe diameter/√lT), and resonates when this natural frequency and the frequency of the intake air in the passage match,
The resonance mainly occurs in the thicker and longer passage, that is, the communication passage 11.
．． A communication hole 12a is formed in the partition wall 12 that partitions the second surge tank 71, 72, and an on-off valve 13 for opening and closing the eye hole 12a is provided in the communication hole 12a.

Next, the operation of the above embodiment will be explained.

When the engine 1 is operating, intake air taken in from an air cleaner (not shown) flows from the merging passage 9 on the upstream side of the intake device 4 to the first. They are distributed into the second divided passages 81 and 82, and the first divided passages are respectively introduced into the second divided passages 81 and 82. The first throttle valve passes through the second throttle valve 101 and 102. It flows into the second surge tank 71,72. This intake air passes through the independent intake passages 61 to 63 from the first surge tank 71 to the first to third banks in the first bank 21.
It is distributed and supplied to the third cylinders 31 to 33 and from the second surge tank 72 to the fourth to sixth cylinders 34 to 36 in the second bank 22 through independent intake passages 64 to 66. In that case, the three cylinders 31 to 33 in the first bank 21 are not adjacent in the intake order, and the three cylinders in the second bank 22 are
Since the intake orders of the two cylinders 34 to 36 are not adjacent to each other, between the cylinders 31 to 33fil of the first bank 21 and the cylinders 34 to 36 of the second bank 22, the intake boats 51 to 53 or 54 to 56 are When the pressure waves generated due to the opening and closing of the first . Intake vibration occurs in the second surge tank 71, 72 at a frequency corresponding to the engine speed. When the communication hole 12a formed in the partition wall 12 between the second surge tanks 71 and 72 is closed by the on-off valve 13, the first passage 111 in the first surge tank 71 and the communication passage 11 and the second surge Second passage 1 in tank 72 and communication passage 11
12 become two mutually independent resonance spaces X,
In a predetermined rotational range of the engine 1, these resonance air aX, In that case, the first. The second passages 111 and 112 are the first passages 111 and 112, respectively. Since it is sufficiently thick and short compared to the second divided passage 81.82, the communicating passage 11 forms a resonant space, and the elongated first and second divided passages 81.82 form the resonant space. The resonance phenomenon in X and X is not inhibited. Further, since there are no obstacles such as a throttle valve in the communication path 11, for example, the first. Unlike in the case where the second divided passages 81 and 82 form resonance spaces, the problem that large positive pressure waves generated by resonance are attenuated by the throttle valves 101 and 102 does not occur. Therefore, the above-mentioned resonance space rix.

The large positive pressure wave generated at
3 and 34 to 36, respectively, and as a result, as shown by the arrow X in the output torque characteristic (c) of FIG. will be effectively increased. The peak of the output torque on the high engine rotation side shown by the arrow V in the output torque characteristic (c) of FIG. 2 is obtained by the inertial effect of the intake air in each of the independent intake passages 61 to 66.

In addition, 1st. Communication hole 12 between second surge tanks 71 and 72
When the on-off valve 13 provided in the engine a is opened, the natural frequency of the resonant space becomes high, and an output torque characteristic having a peak 2 on the high engine speed side is obtained as shown by reference numeral (d) in FIG. Therefore, if the opening/closing valve 13 is controlled to open/close at engine speeds N1 and N2 where the two characteristics (c) and (d) intersect,
As shown by the thick line in FIG. 2, it is possible to obtain high output torque over a wide operating range.

[Brief explanation of the drawing]

1st. FIG. 2 shows an embodiment of the present invention, FIG. 1 is a cutaway plan view of essential parts of an engine intake device, and FIG. 2 is an output torque characteristic diagram of the intake device. Further, FIG. 3 is a schematic configuration diagram of an intake device showing a conventional example, and FIG. 4 is an output torque characteristic diagram of the intake device showing problems of the conventional example. 1... Engine, 31-33. 34-36... Cylinder group, 4... Intake device, 51-56... Intake port,
71.72...Intake gathering part (surge tank), 81.
82...Divided passage, 101.102...Throttle valve, 11...Resonance tube (communication passage). 2nd M Engine 0g Senmoku Moan Figure 3 41i Mouth Engine Mouth Maki-

Claims (1)

[Claims] (1) Two intake collecting parts each communicating with the intake ports of two cylinder groups whose intake orders are not adjacent to each other, each connected to these two intake collecting parts and merging into one on the upstream side, and a throttle valve. 2. An intake system for a multi-cylinder engine having two divided passages each having a
A resonance pipe is provided that communicates the two intake collecting parts and has no obstructing part inside the pipe, and the length L and the pipe diameter D, which are half of the length of the resonance pipe, are the total length of the two divided passages. 1/2 of
An intake system for a multi-cylinder engine, characterized in that the length l and the pipe diameter d are set to satisfy the following condition: d/√l<D/√L.