JPS5843657Y2 - Internal combustion engine intake system - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an intake device for a small internal combustion engine used in a chain saw or the like.

Conventionally, for the intake system of this type of small internal combustion engine, the carburetor inlet, which is integrally installed in the engine body, and the air cleaner chamber, which is installed independently from the engine body in a vibration-proof manner, have been constructed using a bellows. They are communicated via a soft vibration-isolating tube.

In this case, in a small internal combustion engine where the distance between the air cleaner chamber and the carburetor storage chamber is short, the air flow to the carburetor flows along the bellows-shaped inside surface of the vibration isolation tube, resulting in a turbulent flow! There is a problem in that fuel is sucked into the carburetor during a meeting or the vibration isolating tube is constricted by intake negative pressure, making the atomization state of the fuel in the carburetor unstable and causing fluctuations in engine output.

Additionally, if the strength of the vibration isolating tube is increased, the vibration isolating effect will be insufficient and a large amount of vibration from the engine body will be transmitted to the air cleaner room, resulting in the problem that dust attached to the air cleaner element will flow into the carburetor side. .

In view of the above-mentioned problems, the present invention provides a vibration-isolating tube with a sufficient vibration-isolating effect by arranging a cylindrical insert in the bellows-shaped soft vibration-isolating tube that communicates the carburetor with the air cleaner chamber. The purpose of this is to prevent the vibration isolating tube from being deformed due to intake negative pressure, and to prevent the air flow to the carburetor from becoming turbulent.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An intake system for an internal combustion engine according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 shows a chainsaw using an intake system for an internal combustion engine, which is an embodiment of the present invention. In the figure, numeral 1 is the chainsaw, 2 is the engine body, 3 is the carburetor storage box, 4 is the muffler, and 5 is the saw chain. , 6 is a fan, 7 is an intake pipe, and 8 is a handle.

Here, the engine main body 2 and the carburetor housing box 3 are installed so as to be insulated from vibrations.

This chainsaw 1 is designed to cut wood or the like by driving an engine main body 2 and operating a saw chain 5 using its rotational force.

Next, an embodiment of the present invention will be described with reference to FIGS. 2 and 3.

The carburetor storage box 3 is divided by a partition wall 9 into an upper air cleaner chamber 10 and a lower carburetor storage chamber 11.

In the carburetor housing chamber 11, a carburetor 12, which is attached to the engine body 2 via an intake pipe 7, is housed in a vibration-isolated manner from the carburetor housing box 3.

A bellows-shaped soft vibration isolation tube 14 is attached to the tip of the air suction tube 13 on the inlet side of the carburetor 12, and the vibration isolation tube 14 passes through a through hole 15 formed in the partition wall 9. Further, a flange portion 16 formed at the upper end of the vibration isolating tube 14 is placed on the upper surface of the partition wall 9, so that the carburetor 12 and the air cleaner chamber 10 are communicated with each other.

That is, the carburetor housing box 3 is configured to be able to be displaced relative to the air suction pipe 13 by vibration-proof support.

Front = A cylindrical insert 17 is inserted into the plow tube 14,
A flange 18 formed at the upper end of the cylindrical insert 17 is fixed to the partition wall 9 together with the flange 16 of the vibration isolating tube 14 by screws 19.

The open end of the cylindrical insert 17 is configured to be able to protrude into the air suction pipe 13 when the vibration isolation pipe 14 is contracted.

In the air cleaner chamber 10, an air cleaner element 22 is placed on the partition wall 9 via an intermediate stand 21 having a space 20°20.

The air cleaner element 22 has a partition wall 9 and a lid body 23.
An air suction chamber 25 is formed above the air cleaner element 22.

An air suction gap 26 is formed on one side of the lid body 23, and the air sucked into the air suction chamber 25 through the gap 26 is cleaned of dust and the like by the air cleaner element 22, and then transferred to the space 20. .20 and is sent to the carburetor 12 via a cylindrical insert 17 and an air suction pipe 13.

Reference numeral 30 denotes a hole 31 provided in the lower part of the side wall of the carburetor storage box 3 so that the carburetor 12 can be viewed from the outside.
Reference numeral 33 indicates a cover having a gap 32 that allows air to flow from the outside through the hole 30, and a pin 33 that detachably attaches the cover to the carburetor storage box 3.

In this embodiment, air can flow from the hole 30 to the air cleaner chamber 10 via a through hole 34 provided in the partition wall 9.

Next, to explain the operation of the intake system of the internal combustion engine shown in the figure, while the engine main body 2 is being driven, air A is drawn in through the gap 26.
After dust and the like are removed by the air cleaner element 22, the air is sent into the carburetor 12 via the cylindrical insert 17 and the air suction pipe 13.

At this time, the air flow A does not become turbulent because it flows through the cylindrical insert 17 inserted into the bellows-shaped soft vibration isolating tube 14, and the vibration isolating tube 14 is Even if the cylindrical insert 17 attempts to deform, the deformation is prevented by the cylindrical insert 17.

Therefore, it is possible to select a material for the vibration isolating tube 14 that achieves a sufficient vibration isolating effect, and the air cleaner chamber 10 can be isolated from the vibrations of the engine body 2.

Next, the effects of the intake system for an internal combustion engine according to the present invention will be listed below.

That is, according to the present invention, (1) A cylindrical insert 17 is installed in the bellows-shaped soft vibration-isolating pipe 14 that communicates the air suction pipe 13 on the inlet side of the carburetor 120 connected to the engine main body 2 with the air cleaner chamber 10. Since the air flow A drawn into the carburetor 12 from the air cleaner chamber 10 is turbulent due to the bellows-shaped inner surface of the vibration isolating tube 14 as in the conventional case, or the air flow A is turbulent due to the bellows-shaped inner surface of the vibration isolating tube 14 due to intake negative pressure. The fuel can flow smoothly without pulsation due to deformation, stabilize the atomization state of the fuel in the carburetor, and prevent fluctuations in engine output. and the air cleaner chamber 10 of the carburetor storage box 3, and the bellows-shaped soft vibration-proofing pipe 14.
Since the carburetor storage box 3 is communicated with the air suction pipe 13 through vibration-proof support so that it can be moved relative to the air suction pipe 13, vibration propagation on the engine body 2 side to the air cleaner chamber 10 is minimized. (3) Inside the bellows-shaped soft vibration isolating tube 14, The cylindrical insert 17 fixed to the air cleaner chamber 10 side is fitted coaxially so that its open end can protrude into the air suction pipe 13 when the bellows-shaped soft vibration isolating pipe 14 contracts. There are practical effects such as being able to prevent the vibration isolating tube 14 from swinging in a direction perpendicular to its axis when the vibration isolating tube 14 is contracted.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional plan view of a chainsaw according to an embodiment of the present invention, Fig. 2 is a longitudinal sectional view of an intake system of an internal combustion engine according to an embodiment of the present invention, and Fig. 3 is a sectional view taken along the line ■-■ of Fig. 2. It is. 2... Engine body, 7... Intake pipe, 10... Air cleaner chamber, 12... Carburetor, 13... Air intake pipe, 14... Accordionic soft vibration isolation pipe, 17. ...Tubular insert.

Claims (1)

[Scope of utility model registration request] The carburetor 12 is attached to the engine body 2 via the intake pipe 7, and the air intake pipe 13 on the inlet side of the carburetor 120 is connected to the air cleaner chamber 10 of the carburetor storage box 3 via a bellows-shaped soft vibration-proofing pipe 14. The carburetor housing box 3 is connected to the air suction pipe 13 so as to be movable relative to the air suction pipe 13 by vibration-proof support, and inside the bellows-shaped soft vibration-proof pipe 14 is fixed to the air cleaner chamber 10 side. An intake system for an internal combustion engine, characterized in that a cylindrical insert 17 is fitted coaxially into the air intake pipe 13 so that its open end can protrude into the air intake pipe 13 when the bellows-shaped soft vibration isolating pipe 14 contracts. .