JPH06200828A - Intake system of engine - Google Patents

Abstract

PURPOSE:To deliver an adequate air-fuel mixture by always stabilizing the pressure in the float chamber of a carbureter of an automobile. CONSTITUTION:In the intake system of an engine in which an air cleaner 1 and a carbureter 2 are connected through a pipe 3, and the inside of the float chamber 5 in the carbureter 2 and the opening of the outlet side of the pipe 3 are connected through an air vent pipe 8, the passage end of the connection at the outlet side of the pipe 3 is expanded, and an air passage by the air vent pipe 8 is opened at the inlet side from the passage end. Although a colamnar vibration is generated in the pipe 3 connected to the outlet side of the air cleaner 1 by the intake stroke of the engine, a node A of the colamnar vibration is formed at the passage end, and the position at the input side of the node A where the influence of the colamnar vibration is little, and the float chamber 5 are to be communicated, so as to reduce the pressure variation in the float chamber 5. Since an air-fuel mixture with an adequate air-fuel ratio can be fed, the fuel consumption and the running feel can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air intake system for an automobile engine, and more particularly to an air intake system for an engine in which the carburetor functions efficiently.

[0002]

2. Description of the Related Art Generally, an air intake system for an automobile engine takes in outside air from an air cleaner and changes the amount of air by a carburetor to send an appropriate air-fuel mixture. In many engine bodies, an air cleaner and a carburetor are integrally attached. As shown in FIG.
The carburetor 2 and the carburetor 2 are connected to each other via a pipe 3 having a narrowed diameter on the output side and aligned with each other. An air cleaner element 4 is mounted inside the air cleaner 1.

Further, as shown in FIG. 5, a carburetor 2 is provided with a float chamber 5, in which a float 6 and a needle valve 7 are mounted. This float chamber 5
The inside of the valve and the output side opening of the pipe 3 are communicated with each other by an air vent pipe 8 so that the float chamber 5 is communicated with the outside air and the vapor of the fuel due to this is not discharged to the outside.

[0004]

By the way, the intake air pulsation due to the operation of the engine may cause air column vibration in the pipe 3. At this time, if the opening of the air vent pipe 8 is located at the output side opening of the pipe 3, the pressure applied to the air vent pipe 8 becomes smaller (or larger) only at a certain value of the engine speed, and the float chamber 5 Since the internal pressure also changes, the air-fuel mixture becomes lean (or rich), making it difficult to stably send an appropriate air-fuel mixture.

Therefore, the length of the pipe 3 is made variable,
As disclosed in Japanese Patent Laid-Open No. 62-70649, there is a structure in which two air vent pipes are arranged so as not to affect the pressure in the float chamber, but both have complicated structures. Therefore, the workability is poor and the cost is high.

It is an object of the present invention to provide an intake system for an engine which has a simple structure and which suppresses fluctuations in pressure inside the float chamber.

[0007]

In order to achieve the above object, the present invention has an air cleaner and a carburetor connected in series through a pipe, and the inside of a float chamber provided in the carburetor and the opening on the output side of the pipe. In an intake device for an engine, which communicates with a portion by an air vent pipe, a passage end of the output side connecting portion of the pipe or the air cleaner is expanded, and an air passage by the air vent pipe is opened on the input side from the passage end. .

[0008]

Since the present invention is configured as described above, air column vibration is generated in the pipe connected to the output side of the air cleaner due to the intake stroke of the engine. Nodes are formed. On the input side of this node, the influence of air column vibration is small, and this portion communicates with the float chamber, and pressure fluctuations in the float chamber are reduced.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the air cleaner 1 and the carburetor 2 are connected via a pipe 3, and an air vent pipe 8 extends inside the pipe 3. In this case, since the output side pipe diameter of the pipe 3 is larger than the input side pipe diameter of the carburetor 2 and the passage is sharply narrowed, a node A for air column vibration is formed at this connection point, and the air vent pipe is formed. 8 extending length is pressure stable, node A
Make the length so that it opens at a position beyond.

Therefore, the vibration of the air column generated in the pipe 3 causes the inlet end of the carburetor 2 to be the node A, and the air vent pipe 8 opens at a stable position of the air, so that the pressure inside the float chamber 5 is reduced. Fluctuation becomes small, the proper mixture can always be sent, and the efficiency of the engine can be improved.

Next, a case where the output side passage of the air cleaner 1 is expanded at the connecting portion between the air cleaner 1 and the pipe 3 will be described with reference to FIG. In this case, the passage connected to the air vent pipe 8 extends to a position facing the inside of the air cleaner 1. That is, the tubular passage 9 is formed inside the pipe 3 (see FIG. 3), and the air vent pipe 8 is formed.
A nipple 10 for connecting to the tubular passage 9 is provided on the pipe side, and an extension pipe 11 for connecting to the tubular passage 9 is fixed in the air cleaner 1. Therefore, during assembly, the air vent pipe 8 is communicated with the extension pipe 11 in the air cleaner 1, and the interior of the air cleaner 1 and the float chamber 5 are communicated with each other.

With the above-mentioned structure, the air column vibration generated in the pipe 3 forms the node A at the connecting portion of the air cleaner 1, and the opening end of the extension pipe 11 is located on the upstream side where the air column vibration is generated. Therefore, the fluctuation of the pressure applied to the air vent pipe 8 becomes small, and the fluctuation of the pressure inside the float chamber 5 also becomes small. As a result, the proper mixture can be stably sent, and the efficiency of the engine can be improved.

[0013]

Since the present invention is configured as described above, since the location where the pressure does not fluctuate much due to air column vibration communicates with the float chamber, the pressure fluctuation in the float chamber can be reduced. Since the air-fuel mixture having an appropriate mixing ratio can be constantly supplied, the fuel consumption and the traveling feel can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of an intake system for an engine according to an embodiment of the present invention.

FIG. 2 is a side sectional view of an intake device for an engine of another embodiment.

FIG. 3 is a sectional view taken along line BB of the intake device shown in FIG.

FIG. 4 is a side sectional view of a conventional engine intake device.

5 is a cross-sectional view of an essential part on the carburetor side shown in FIG.

[Explanation of symbols]

 1 Air cleaner 2 Carburetor 3 Pipe 5 Float chamber 8 Air vent pipe Section A

Claims (1)

[Claims] 1. An air intake system for an engine, wherein an air cleaner and a carburetor are connected through a pipe, and an inside of a float chamber provided in the carburetor and an opening on an output side of the pipe are connected by an air vent pipe. An intake device for an engine, wherein a passage end of a pipe or an output side connecting portion of an air cleaner is expanded, and an air passage by an air vent pipe is opened on an input side from the passage end.