JPH0123656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an internal combustion engine, particularly to an improvement in an intake system for a supercharged internal combustion engine in which a supercharger is interposed in an intake passage upstream of a throttle valve.

(Prior art) As a conventional intake system for an internal combustion engine with a supercharger,
For example, the one described in Japanese Patent Application Laid-open No. 14915/1983 is known. This intake system has a supercharger installed upstream of the throttle valve in the intake passage, and the flow rate of the intake air taken in through the air cleaner is measured with a hot wire airflow meter, and then compressed by the supercharger. After that, supercharging is carried out into each cylinder from the intake manifold via the throttle valve.

However, in such conventional intake devices, the intake passage between the air cleaner and the supercharger was formed by an intake pipe with a substantially uniform cross-sectional area, so it was necessary to operate the throttle valve during supercharging. When it closes suddenly,
The compressed air between the throttle valve and the turbocharger flows back into the intake passage on the upstream side of the turbocharger, producing an abnormal noise, which is then diffused outside from the air intake port of the air cleaner, causing discomfort. In addition to the noise generated, there was a problem that the air flow meter installed upstream of the supercharger incorrectly measured the amount due to the backflow of air. Furthermore, for example, in an engine mounted on a vehicle such that the longitudinal direction of the engine body is arranged parallel to a direction perpendicular to the direction of vehicle travel, it is generally necessary to prevent the fuel supply system from being damaged in the event of a vehicle collision. For this purpose, the intake device, which is adjacent to the fuel supply system, is arranged at the rear of the vehicle than the engine main body, and the exhaust device is arranged at the front of the vehicle from the engine main body. When a supercharger is attached to such an engine, the supercharger is disposed on the exhaust system side, so the intake system upstream of the supercharger has to be disposed on the exhaust system. As a result, heat from the exhaust system is transferred to the intake system, heating the intake air, making it impossible to obtain the desired intake air filling efficiency, resulting in a problem in that the engine output cannot be improved.

(Object of the Invention) The present invention provides a predetermined silencer in the intake passage upstream of the turbocharger and downstream of the intake state detection means, and suppresses an increase in intake resistance while suppressing the throttle during operation of the turbocharger. The purpose of this invention is to prevent noise generation due to backflow of pressurized air when the valve is fully closed, prevent erroneous metering by intake state detection means, and further improve engine output.

(Structure of the Invention) In order to achieve the above object, the present invention provides an intake system for an internal combustion engine in which a supercharger and an intake state detection means are interposed in an intake passage upstream of a throttle valve. In the intake passage located downstream of the intake state detection means, there is an expansion chamber having a larger cross-sectional area than the intake passage, and an inner diameter that communicates with the intake passage upstream of the expansion chamber and projects into the expansion chamber is tapered. a cylindrical upstream pipe; and a cylindrical downstream pipe that communicates with the intake passage downstream of the expansion chamber, projects into the expansion chamber, and has an upstream end opening having approximately the same diameter as the downstream end opening of the upstream pipe. A muffler is provided and the muffler is disposed between the exhaust system of the engine and the radiator cooling fan.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

1 to 5 show an embodiment of the present invention, in which FIG. 1 is a schematic diagram showing the entire intake system, FIG. 2 is a sectional view of a silencer, and FIG. −
4 is a plan view showing the shaft state of the intake device mounted on a vehicle, and FIG. 5 is a view taken along the V arrow in FIG. 4.

In FIG. 1, 1 indicates an engine body, 2 an intake system, 3 an exhaust system, and 4 a turbocharger. The intake device 2 is constructed by connecting an intake manifold 6, a throttle chamber 7, an impeller housing 8, a body 9 of a hot wire air flow meter, and an air cleaner 10 in this order from the intake port 5 side, and the intake air formed inside these is connected. Intake air is supplied into each cylinder 12 through a passage 11. In addition, 13 is a throttle valve installed in the throttle chamber 7, 14 is an impeller installed in the impeller housing 8, and 1 is an impeller installed in the impeller housing 8.
Reference numeral 5 indicates a hot wire air flow meter built into the body 9. Further, the cross-sectional area of the portion of the intake passage 11 excluding the air cleaner 10 and the impeller housing 8 is approximately uniformly circular. Here, a muffler 20 is interposed in the intake passage 11 on the upstream side of the impeller 14 and downstream of the air flow meter 15. This silencer 2
0 has a large capacity (having a cross-sectional area larger than the cross-sectional area of the intake passage 11) due to the cylindrical housing 21 made of resin, as shown in detail in FIGS. 2 and 3.
An expansion chamber 22 is defined, and an upstream tube 23 having a tapered inner diameter and a cylindrical shape and a downstream tube 2 having a cylindrical shape are disposed within the expansion chamber 22.
4 are protruding and facing each other. The upstream end of the upstream pipe 23 is connected to the body 9 of the air flow meter via an elastically deformable tube 25, and the downstream end of the downstream pipe 24 is connected to the impeller housing 8 via a similarly flexible tube 26.
It is connected to the. i.e. upstream pipe (inlet pipe)
23 is the intake passage 11 on the upstream side of the muffler 20;
Furthermore, the downstream pipes (outlet pipes) 24 are connected to the intake passages 11 on the downstream side of the muffler 20, respectively. In addition, these upstream pipes 23 and downstream pipes 24
are arranged coaxially and face each other at a predetermined interval L in the expansion chamber 22. That is, each opening 23A, 24A into the expansion chamber 22 to the upstream pipe 23 and the downstream pipe 24 (the downstream end opening 23 of the upstream pipe 23
A and the upstream end opening 24A of the downstream pipe 24 are opposed to each other by a predetermined distance L, and this distance L is the diameter of these circular openings 23A and 24A (these diameters D ₀ and D ₁ are approximately equal). ) D ₀ and D ₁ are set to be approximately the same (D ₀ ≒D ₁ ≒L). Note that the inner diameter of the end of the upstream pipe 23 protruding into the expansion chamber 22 has an inclination of a predetermined angle θ and becomes continuously smaller (it tapers toward the downstream side). Further, the axes of the upstream pipe 23 and the downstream pipe 24 are made to coincide with the axis of the housing 21. Further, a heat shield plate 30 made of metal, for example, is attached to the outside of the silencer 20 by a support boss 21A so as to cover the outer surface of the resin housing 21, and this heat shield plate 30 is shown in FIG. As shown, it is fixed to the housing 21 with a predetermined distance from the outer surface so as to cover about 1/4 of the outer surface of the housing 21 in the circumferential direction. If the muffler 20 is made of resin as in this embodiment, it can be made lighter.

FIG. 4 and FIG. 5 show the installed state of the intake device. The engine main body 1 is mounted on a vehicle so that the longitudinal direction of the engine main body is arranged parallel to a direction perpendicular to the vehicle traveling direction. The intake device 2 is disposed at the rear of the engine body 1, the exhaust device 3 is disposed at the front of the engine body 1, and the supercharger 4 is interposed in the exhaust device 3. The silencer 20 is arranged on the front side of the supercharger 4,
As shown in FIG. 4, the heat shield plate 30 is connected to the silencer 2 so as to block radiant heat from the exhaust device 3 such as the supercharger 4.
It covers the outer surface of the lower rear side of 0. Further, an electric fan 31 is disposed in front of the muffler 20 to blow cold air from a radiator 32 onto the muffler 20 and guide it to the space between the heat shield plate 30 and the outer surface of the housing 21.

In addition, 35 in Fig. 1 indicates the turbine wheel.
6 indicates a swing valve (exhaust bypass valve).

Next, the effect will be explained.

During supercharging operation of the engine 1, the impeller 14 of the turbocharger 4 rotates at high speed (for example,
100000r.pm) to compress the intake air and compress cylinder 12.
supercharge. At this time, if the throttle valve 13 is suddenly closed (such as during sudden braking), the impeller 1
The high-pressure air in the intake passage 11 on the downstream side of the impeller 14, which has a low pressure (approximately atmospheric pressure), expands and flows backward into the intake passage 11 on the upstream side of the impeller 14, which has a low pressure (approximately atmospheric pressure).
generates noise. This noise cannot be muffled in a conventional air intake system using only an air cleaner and is dissipated to the outside, but in the present invention, it can be muffled by the muffler 20. That is, the high-pressure air that flows backward flows into the expansion chamber 22 and its pressure is reduced, and at the same time, it resonates in a predetermined frequency range and is therefore muffled.
In particular, the upstream pipe 23 and the downstream pipe 24 as the muffler 20
Since the above-mentioned structure is used, in which the above-mentioned and the above-mentioned electrodes penetrate oppositely into the expansion chamber 22, it is possible to muffle the sound over a wide range from 200 Hz to 2 kHz. In the case of the above-mentioned muffler 20, since the downstream end of the upstream pipe 23 is formed to have a tapered inner diameter, the flow velocity of the intake air increases and the air flows through the opposing downstream pipe 2 without being diffused.
4, and the increase in suction resistance is extremely small. Moreover, since air does not flow backward in the air flow meter 15, the air flow meter 15 does not erroneously measure the amount. Further, the heat shield plate 30 prevents radiant heat from the exhaust device 3 such as the supercharger 4 from reaching the muffler 20 . moreover,
The electric fan 31 cools the muffler 20 during operation. In addition to directly colliding with the muffler 20, the cold air is introduced into the gap between the heat shield plate 30 and the outer surface of the housing 21, so that the cooling effect is improved.

(Effects) As explained above, according to this invention,
To suppress an increase in intake resistance, to prevent noise generation due to backflow of pressurized air when the throttle valve is fully closed during turbocharger operation, to prevent incorrect metering by an intake state detection means, and to further improve engine output. Can be done.

[Brief explanation of drawings]

1 to 5 show an embodiment of an intake system for an internal combustion engine according to the present invention, FIG. 1 is a schematic overall configuration diagram thereof, FIG. 3 is a view in the direction of the - arrow in FIG. 2, FIG. 4 is a plan view of the device when mounted on a vehicle, and FIG. 5 is a view in the direction of the arrow in FIG. 4. 3... Exhaust device, 4... Supercharger, 11... Intake passage, 13... Throttle valve, 14... Impeller, 15
... Air flow meter, 20 ... Silencer, 31 ...
...Electric fan.

Claims (1)

[Claims] 1. In an intake system for an internal combustion engine in which a supercharger and an intake state detection means are interposed in an intake passage upstream of a throttle valve, the intake passage is located upstream of the supercharger and downstream of the intake state detection means. An expansion chamber having a larger cross-sectional area than the intake passage, an upstream tube having a tapered inner diameter and a cylindrical shape that communicates with the intake passage upstream from the expansion chamber and projects into the expansion chamber, and an intake passage downstream from the expansion chamber. A cylindrical downstream pipe that communicates with and projects into the expansion chamber and has an upstream end opening having approximately the same diameter as the downstream end opening of the upstream pipe is provided, and the silencer is connected to an engine exhaust system and a radiator cooling fan. An intake device for an internal combustion engine, characterized in that it is disposed between.