JPS59218357A - Suction noise damping device for internal-combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To damp the pulsation of outlet pressure of a supercharger ample enough with a samll-sized surge tank and reduce a suction noise to the lowest possible extent, by installing a pre-chamber being smaller in displacement than the surge tank jointly in a suction passage between the surge tank and the supercharger. CONSTITUTION:When an engine E is operated, a supercharger 11 is driven by dint of output of the engine E. Likewise, when a bypass 18 is clased by a bypass valve 19, the air cleaned at an air cleaner 12 is pressurized by the supercharger 11 and turned into an air-fuel mixture by way of a pre-chamber 10, a surge tank 9 and a carburetor 8, then charged into a combustion chamber of the engine E. Stemming from an intermittent surpercharging action of the displacement type supercharger 11, if outlet pressure of the superchargre 11 becomes pulsated, this pulsatory motion is damped by the small displacement pre-chamber 10, while the residual pulsation run past the pre-chamber is, in turn, damped by the large displacement surge tank 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air noise reduction device for an internal combustion engine equipped with a positive displacement supercharger in an intake passage.

Since positive displacement superchargers perform supercharging intermittently, the outlet pressure of the supercharger pulsates during operation, and the vibration of the air column in the intake passage due to this pulsation contributes to air supply noise. . In order to reduce such intake air noise, it is conventionally known to install a surge tank in the intake path downstream of the turbocharger to dampen the pulsation of the turbocharger outlet pressure. In order to sufficiently attenuate outlet pressure pulsations, the volume of the surge tank must be considerably increased, but increasing the size of the surge tank causes the intake system to expand in the radial direction, making it difficult to fit into narrow engine rooms such as automobiles. In this case, the problem arises that interference occurs with adjacent equipment.

The present invention was proposed in view of such problems, and consists of a pre-chamber having a smaller volume than the surge tank in the air intake path between the surge tank and the supercharger, thereby making the surge tank extra large. It is an object of the present invention to provide the above-mentioned device which can sufficiently attenuate the pulsation of the outlet pressure of the supercharger and reliably reduce the intake air noise even without the use of a supercharger.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. An internal combustion engine E has a cylinder head 1 having an air intake.

Suction and exhaust ports 4.5 opened and closed by exhaust valves 2 and 3
These suction and exhaust boats 4 and 5 have suction.

Exhaust passages 6 and 7 are connected to each other.

A variable venturi carburetor 8, a surge tank 9, a prechamber 10, a positive displacement supercharger 11 consisting of a vane pump, and an air cleaner 12 are provided in the intake passage 6 in this order from the downstream side, that is, from the intake port 4 side. That is, prechamber 1
0 is placed between the surge tank 9 and the supercharger 11, and the volume of the prechamber 10 is that of the surge tank 9. The carburetor 8 is located between the surge tank 9 and the supercharger 11.
This intake passage 13 has a central venturi portion 13.
Throttle valve 14 on the downstream side across α, choke valve 15 on the upstream side
will be installed. In addition, a float chamber 1 is located directly below the intake passage 13.
6 is provided, and the fuel stored in the chamber 16 is transferred to a nozzle 17.
The liquid is ejected through the venturi section 13a.

The supercharger 11 is connected to the engine E via a suitable transmission device (not shown).
A bypass 18 that bypasses this supercharger 11 is connected to the intake passage 6, and this bypass 18 is equipped with a bypass valve 1 that can open and close it as needed.
9 will be installed.

Next, the operation of this embodiment will be explained.

When the engine E is operated, the supercharger 11 is driven by the output of the engine E. If the bypass 18 is closed by the bypass valve 19 during this drive, the air purified in the air cleaner 12 will be pressurized by the supercharger 11, and will pass through the prechamber 10 and surge tank 9 in order to the carburetor 8.
The mixture is mixed with the fuel ejected from the nozzle 17 to form an air-fuel mixture, and the flow rate of this air-air mixture is adjusted by the throttle valve 14, and the air-fuel mixture is charged into the combustion chamber of the engine E from the intake boat 4.

In this way, the charging efficiency of the engine E can be improved, and its output can be increased.

During this time, if the outlet pressure of the supercharger 11 pulsates due to the intermittent supercharging 6 action of the positive displacement supercharger 11, the pulsation is first attenuated by the small volume prechamber 10 and passes through it. This residual pulsation is damped by the large volume surge tank 9. In this way, the pulsations are effectively damped in two stages.

If the bypass valve 19 is opened while the engine E is running, the bypass 18 becomes conductive and the supercharger 110 is operated.

Since the outlets are short-circuited, the air that has passed through the air cleaner 12 is sucked into the carburetor 8 side through the bypass 18, and the supercharger 11 only idles, stopping its supercharging action. Such non-supercharging control is performed when the engine E is idling, under low load, and when the engine E is running at full speed.

As described above, according to the present invention, the pulsation of the outlet pressure of the positive displacement supercharger is attenuated in two stages by the prechamber and the surge tank, so the prechamber only needs to have a smaller volume than the surge tank. Of course, the pulsation can be sufficiently attenuated without significantly increasing the volume of the surge tank, achieving a significant reduction in air supply noise. Moreover, since the prechamber and surge tank do not excessively expand the intake system in the radial direction, the intake system can be easily laid out even in a narrow engine room without interfering with adjacent equipment.

[Brief explanation of drawings]

The drawing is a longitudinal sectional side view of a supercharged internal combustion engine according to an embodiment of the present invention. E... Internal combustion engine, 6... Intake path, 8... Carburetor, 9... Surge tank, 10... Bure chamber, 11... Supercharger, 12
・・・Air cleaner

Claims (1)

[Claims] In a supply air noise reduction device for a turbocharged internal combustion engine that has a surge tank installed in the intake path downstream of a positive displacement turbocharger,
A supply air noise reduction device for an internal combustion engine with a supercharger, characterized in that a pre-chamber having a smaller volume than the surge tank is interposed in the intake path between the surge tank and the supercharger.