JP2002115609A - Suction structure for multicylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently reduce suction pulsation in a multicylinder engine, if larger, in a compact structure. SOLUTION: This suction structure for the multicylinder engine with aftercoolers 13a-13c and turbochargers 10a-10c comprises a plurality of suction manifolds 6a-6b independently mounted in a plurality of cylinders, respectively, and the aftercoolers 13a-13c provided in the suction manifolds 6a-6c, respectively, wherein upstream side chambers 15a in suction paths parted with the aftercoolers 13a-13c communicate with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake structure for a multi-cylinder engine.

[0002]

2. Description of the Related Art In a large-sized multi-cylinder engine, a turbocharger is used in an intake structure to improve the charging efficiency of intake air in order to obtain good performance such as torque characteristics. This turbocharger is used for each of a plurality of cylinder heads provided for each cylinder, for example, one for each intake manifold provided for every three cylinder heads. For this reason, in the case of a V-type 18-cylinder diesel engine in which cylinders are arranged in series in nine cylinders on one side, three intake manifolds on one side are provided independently, and the inlet side (upstream side) of each intake manifold is provided. Each of the ducts of the turbocharger is connected.

In such an intake structure of a large-sized multi-cylinder engine, one intake manifold is provided for every three cylinders and a turbocharger connected to the intake manifold, and the intake manifolds of nine cylinders arranged in series are provided. Since the order is not continuous, the intake pressure fluctuates among the intake manifolds independently provided corresponding to three cylinders. Also, in a turbocharger driven by exhaust gas from a cylinder, since the order of explosion of the cylinder is not continuous, the exhaust energy that enters the turbocharger varies, and the supercharging pressure varies for each intake manifold.

[0004] In order to solve such a problem, as disclosed in Japanese Utility Model Registration No. 2593149, there is a configuration in which the intake manifolds are intermittently communicated with each other.

[0005] In the above-mentioned conventional technique, the intake manifold can be communicated with each other or cut off in accordance with the rotational speed of the engine to improve the charging efficiency of the intake system in accordance with the rotational speed. .

[0006]

However, when an aftercooler is provided in the intake manifold, the configuration in which the intake manifolds are simply connected to each other as in the prior art described above can eliminate variations in intake pressure. could not.

In this case, due to variations in the exhaust energy entering the turbocharger and variations in the performance of each turbocharger, etc., the intake pressure between the ventilation passages provided independently of each other in the aftercooler and the intake manifold is reduced. Variations are possible. Therefore, if the other intake manifolds communicate with each other only in the downstream chamber of the aftercooler of the intake manifold between the intake passages, the flow of this communicating portion becomes substantially perpendicular to the main intake flow between the passages. In addition, a flow velocity distribution is generated between the cylinders, and the intake air amount varies. Also, due to the discontinuity of the intake order by each cylinder, in each intake passage,
A pulsation of the intake pressure occurs.

The present invention has been made in view of the above, and has been made in consideration of the above. In an intake structure of an engine using a plurality of intake manifolds and incorporating an aftercooler inside each of the intake manifolds, an intake structure between the intake manifolds is provided. It is an object of the present invention to provide an intake structure of a multi-cylinder engine capable of equalizing an air flow rate and preventing pulsation of intake pressure due to discontinuous intake order of cylinders.

[0009]

To achieve the above object, a first invention of an intake structure for a multi-cylinder engine according to the present invention is directed to a multi-cylinder engine having an aftercooler and a turbocharger. In the intake structure, one intake manifold is independently installed for each of a plurality of cylinders, an aftercooler is provided in each intake manifold, and the upstream side chambers of each intake passage partitioned by the aftercooler communicate with each other. Has become.

According to the first aspect of the present invention, since the upstream chambers of the intake manifold having the aftercooler are communicated with each other, the scattered pressure from each turbocharger flowing into the connected upstream chambers is uniform. Be transformed into Also, the intake air flow disturbed by the flow from the communication passages communicating with each other passes through the after cooler with a rectifying effect located downstream of the intake air flow, so that the flow is made uniform.

According to a second aspect of the present invention, in the intake structure of a multi-cylinder engine provided with a turbocharger with an aftercooler, a plurality of one intake manifolds are independently mounted for each of a plurality of cylinders, and the after manifold is provided in each intake manifold. A cooler is provided, and the upstream chamber and the downstream chamber of each intake manifold partitioned by the aftercooler are configured to communicate with each other between the upstream chambers and between the downstream chambers among the plurality of intake manifolds.

According to the second aspect of the present invention, not only the downstream chamber of the intake manifold partitioned by the aftercooler but also the upstream chamber communicates with each of the other intake manifolds. Since the aftercooler has a rectifying effect, the flow velocity distribution of the intake air in each intake manifold is made uniform, and the intake flow rate between the intake passages can be made uniform.

Also, due to the discontinuity of the intake sequence, the pulsation of the intake pressure generated in each intake passage can be reduced by communicating with the downstream side of the after cooler of each intake manifold.

From these facts, even in a large cylinder engine, the pulsation of the intake air can be efficiently reduced with a compact configuration, the volumetric efficiency can be increased, and the supercharging efficiency can be improved.

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows a V in which the apparatus of the present invention is to be implemented.
FIG. 1 shows an example of a multi-cylinder, for example, a V-type 18-cylinder diesel engine, and FIG.

In FIG. 2, cylinders 1a, 1b, 1
C, 1d, 1e, 1f, 1g, 1h, and 1i are arranged in series on each side, each having nine units, and a unit injector (fuel injection device) 2 and a fuel hole (see FIG. And a cylinder head 5 having an intake passage 4 and the like communicating with the respective intake ports of the cylinders 1a to 1i.
a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i
Is stuck. Then, as shown in FIG. 1, three cylinder heads 5a to 5
One intake manifold 6a, 6b, 6c is fixed to each side surface of c, 5d-5f, 5g-5i. In FIG. 1, the numbers shown on the cylinders 1a to 1i corresponding to the cylinder heads 5a to 5i indicate the order of the explosion in two rotations (720 degrees) of the crankshaft.

As shown in FIGS. 1 and 2, each of the intake manifolds 6a to 6c is provided with a duct 11a, 11b, 10c in a respective turbocharger 10a, 10b, 10c.
11c, and is provided between the intake manifolds 6a to 6c and the after cooler covers 12a, 12b, 12c formed at the distal ends of the ducts 11a to 11c.
There is interior decoration. Each of these after coolers 13a to 13
c is supported between the intake manifolds 6a to 6c and the after-cooler covers 12a to 12c with a flange 14 sandwiched therebetween, and the intake manifolds 6a to 6c are upstream at the flanges 14 of the after-coolers 13a to 13c. Partitioned into a side chamber 15a and a downstream chamber 15b, the entire amount of intake air from each of the ducts 11a to 11c is rectified by the after coolers 13a to 13c and flows into the cylinder head.

As shown in FIG. 1, the upstream chambers 15a of the three intake manifolds 6a, 6b, 6c are connected to each other by a communication pipe 16a on the upstream side, and the downstream chambers 15b are connected to each other on the downstream side. The communication pipes 16b communicate with each other.

According to this configuration, each aftercooler 13
The upstream chambers 15a and the downstream chambers 15b of the respective intake manifolds 6a, 6b, 6c partitioned by the flanges 14a to 13c communicate with each other, so that the pressure between the chambers on each side is equalized.

Since the upstream chambers of the intake manifold are communicated with each other, the scattered pressure from each turbocharger flowing into each of the connected upstream chambers is equalized. Further, the intake air flow disturbed by the flows from the communication pipes 16a and 16b is connected to the downstream after-coolers 13a to 13a.
Since it passes through 13c, its flow is made uniform.

Further, since the downstream side chambers of the intake manifold are also communicated with each other, the pulsation of the intake pressure in each intake passage due to the discontinuity of the intake sequence is reduced.

The present inventors examined the volumetric efficiency (ηv:%) of the intake system at a place where a plurality of intake manifolds communicated with each other and at a place where the plurality of intake manifolds did not communicate. Table 1 shows the results.

[0023]

[Table 1]

In Table 1, the first example is a case where there is no communication between a plurality of intake manifolds, the second example is a case where there is no communication between upstream chambers and the case where there is communication between downstream chambers, and the third example is In the case where there is communication between the upstream chambers and no communication between the downstream chambers, the fourth example is a case where the upstream chambers and the downstream chambers are each connected.

According to the results of this experiment, as is clear from the table, the volume efficiency of the intake system is improved when the intake manifolds are connected to each other, but compared to the case where only the downstream chambers are connected to each other (second example). The volume efficiency is better when only the upstream chambers communicate with each other (third example), and the volume efficiency when the upstream chamber and the downstream chamber communicate with each other (fourth example) is further improved. I understand.

FIG. 3 shows pressure changes in the upstream chamber and the downstream chamber of the intake manifold in the above configuration. The horizontal axis in the figure is the rotation angle of the crankshaft, and the explosion order of nine cylinders during this period is NO1 (1a), NO2 (1b)
NO4 (1d), NO6 (1f), NO8 (1h), N
O9 (1i), NO7 (1g), NO5 (1e), NO
3 (1c), each of which is performed every 80 degrees. At this time, the pressure change in the upstream chamber of the intake manifold is as shown by a thick line (upper side) in the figure, and the pressure change in the downstream chamber is as shown by a thin line (lower side). In the intake system at this time, while the rotation angle of the crankshaft over 720 degrees ranges from 180 degrees to 410 degrees (230 degrees), A is N
O5 cylinder intake valve open period, from 500 degrees to 10
B is the intake valve open period of the NO4 cylinder during the period (230 degrees), and C is the intake valve open period of the NO6 cylinder during the period from 580 degrees to 90 degrees (230 degrees).

This pressure measurement is performed when the plurality of intake manifolds are not connected to each other at all (first example), when only the downstream chambers are connected to each other (second example), and when the upstream chambers and the downstream chambers are connected. A case in which they communicate with each other (fourth example) was performed.

As a result, the pressure in the upstream chamber and the pressure in the downstream chamber in the first example are shown by dotted lines, in the second example are shown by chain lines, and in the fourth example are shown by solid lines.
In this measurement result, the height of the unevenness of the wavy line indicating each measurement result is larger in the first example (dotted line) and smaller in the second example (dashed line) in both the upstream chamber and the downstream chamber.
Further, the irregularities of the fourth example (solid line) are smaller than those of the first and second examples, and the fourth example, that is, each of the cases where the upstream chambers of the plurality of intake manifolds and the downstream chambers communicate with each other are connected. It can be seen that the pressure in the chamber was made uniform.

In FIG. 3, part a is a part where the pressure drops due to the suction of the fifth exploding cylinder, and part b is a part where the pressure is affected by the suction of the fourth exploding cylinder. Is a part where the pressure decreases due to the effect of the cylinder that explodes sixth.

In the above embodiment, an example is shown in which a turbocharger is provided for each intake manifold. However, the present invention can be applied to a case where one common turbocharger is used for a plurality of intake manifolds.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of an engine to which the present invention is applied.

FIG. 3 is a diagram showing a pressure change of an intake manifold during two rotations of a crankshaft.

[Explanation of symbols]

1a to 1i: cylinder, 2: unit injector, 4
... intake passages, 5a-5i ... cylinder heads, 6a-6c
... intake manifolds, 10a to 10c ... turbochargers, 11a to 11c ... ducts, 12a to 12c ... after cooler covers, 13a to 13c ... after coolers, 14 ... flanges, 15a ... upstream chambers, 15b ... downstream chambers, 16a, 16b ... Communication pipe

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 35/10 311 F02M 35/10 301P

Claims (2)

[Claims] In an intake structure of a multi-cylinder engine provided with an aftercooler (13a to 13c) and a turbocharger (10a to 10c), one intake manifold (6a to 6c) is provided for each of a plurality of cylinders.
b) are independently mounted, and aftercoolers (13a-13) are installed in each intake manifold (6a-6b).
c), wherein the upstream chambers (15a) of each intake passage partitioned by aftercoolers (13a to 13c) communicate with each other. 2. In an intake structure of a multi-cylinder engine provided with a turbocharger (10a to 10c) with an aftercooler (13a to 13c), one intake manifold (6a to 6c) is provided for each of a plurality of cylinders.
c) are independently mounted, and aftercoolers (13a-13) are installed in each intake manifold (6a-6c).
c), and the upstream chamber (15a) of each intake manifold (6a-6c) partitioned by the after cooler (13a-13c).
A plurality of intake manifolds (6a to 6c) communicate with each other between the upstream chambers (15a) and between the downstream chambers (15b). .