JP2000257519A - Intake duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent suction of water in an intake system of an engine by arranging a tongue piece for opening/closing by intake negative pressure of the engine in a clearance between a hood and an intake duct. SOLUTION: A clearance 5 is formed between an inner wall surface disposed opposite to an intake port 2a of a hood 2 and an outer wall surface of an intake duct 1, and a tongue piece 5 made of an elastic material is arranged. In the case when an engine is rotated with a low speed, suction force is weak, and thereby, water is not sucked to the intake duct 1. When an acceleration pedal is stepped down and rotation of the engine is increased, intake negative pressure force is increased, the tongue piece 5 is pulled up by negative pressure force, the clearance 4 is closed, and suction of water from the clearance 4 is obstructed. Water invades from the suction port 2a of the hood 2 together with air E, and is centrifugally separated in the hood 2 by flow speed in the suction port 2a of the hood 2. And then, it is stuck as water drops on the inner wall surface of the hood 2, and it is possible to avoid suction of water to the intake duct 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake duct for an engine.

[0002]

2. Description of the Related Art As shown in FIG. 4, an intake duct for an engine in a tilt cab vehicle is provided with an intake duct 1 standing upright on the tilt cab, and a hood 2 having an intake port 2a at the upper end thereof for avoiding rain. At the normal position of the tilt cab, the lower end of the intake duct 1 is connected to an air cleaner 3 fixed to a chassis frame or the like, and is separated from the air cleaner 3 when the tilt cab tilts forward.

[0003]

The upper end of the conventional intake duct 1 is covered with a hood 2 to avoid rain and the like. Splash mist and the like of rainwater together with the air E are supplied to the intake duct 1 according to the flow velocity of the intake port 2a of the hood 2.
The function of the hood 2 is reduced by half.

[0004] It is an object of the present invention to provide an intake duct that prevents water from being sucked into an intake system of an engine.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an upright engine intake duct whose upper end is covered by a hood having an intake port, the side being opposite to the intake port of the hood. A gap is formed between an inner wall surface of the air intake duct and an outer wall surface of the intake duct, and a tongue piece is provided in the gap to open and close the gap by negative pressure of intake air of the engine.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an upright intake duct, the upper end of which is a hood 2 having an intake port 2a.
Covered by

According to the present invention, a gap 5 is formed between the inner wall surface of the hood 2 opposite to the intake port 2a and the outer wall surface of the intake duct 1, and the gap 4 is formed in the gap 4 by the negative pressure of the intake air of the engine. A tongue 5 made of an elastic material such as rubber or soft plastic for opening and closing the gap 4 is provided.

In the embodiment of the present invention shown in FIGS. 1 and 3, the tongue 5 is fixed to the intake duct 1 side, and the tip of the tongue 5 contacts the inner wall surface of the hood 2 on the side opposite to the intake port 2a. Thus, the gap 4 is closed.

Since the present invention has the structure as described above, the tongue 5 opens the gap 4 due to the elastic force when the negative pressure of intake air is low at the time of low rotation of the engine with the accelerator returned.
When the intake negative pressure at the time of low rotation of the engine is low, the suction force of rain mist splash mist and the like is reduced, so that water is not sucked into the intake duct 1.

[0010] However, when the accelerator is depressed to increase the rotation of the engine, the intake negative pressure increases, and the tongue piece 5 is pulled up by the intake negative pressure to close the gap 4, and the gap 4 is closed.
Prevents water from being sucked from.

On the other hand, the air E
At the same time, water invades the water,
The water is centrifuged in the hood 2 by the flow velocity of the part, adheres to the inner wall surface of the hood 2 as water droplets, and suction of water into the intake duct 1 is avoided.

Water droplets adhering to the inner wall surface of the hood 2 gradually fall downward and accumulate in gaps on the tongue pieces 5 closing the gaps 4. When pressed downward, the gap 4 is instantaneously opened, the accumulated water is discharged to the outside, and the gap 4 is closed again by the intake negative pressure.

Also, when the accelerator is returned to reduce the negative pressure of the intake air of the engine, the tongue 5 opens the gap 4 and discharges the stored water to the outside.

In the above-described embodiment, the tongue 5 is fixed to the intake duct 1, and the tip of the tongue 5 contacts the inner wall surface of the hood 2 on the side opposite to the intake port 2 a to close the gap 4. The tongue 5 is attached to the intake port 2 of the hood 2.
The same function can be obtained by a structure in which the tip of the tongue piece 5 is fixed to the inner wall surface on the opposite side to a and contacts the outer wall surface of the intake duct 1 to close the gap 4.

[0015]

As described above, according to the present invention, a gap is formed between the inner wall surface of the hood covering the upper end portion of the upright intake duct and opposite to the intake port of the hood and the outer wall surface of the intake duct. The structure in which the tongues are provided in the gap to open and close the gap by the intake negative pressure of the engine is provided. It is centrifuged in the hood and adheres to the inner wall surface of the hood, causing water droplets to fall into the gap on the tongue of the gap closed by the tongue, so that suction of water into the intake duct is avoided, and the negative pressure of intake air from the gap The tongue automatically opens the gap by reducing the negative pressure of the intake air of the engine by the weight of the water itself and the return of the accelerator, and the accumulated water is smoothly discharged outside. It can be discharged.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a perspective view of an intake duct of a tongue attaching portion.

FIG. 4 is a side view of a conventional intake duct.

[Explanation of symbols]

 Reference Signs List 1 intake duct 2 hood 2a intake port 3 air cleaner 4 gap 5 tongue piece

Claims (1)

[Claims] An upright engine intake duct whose upper end is covered by a hood having an intake port, wherein a gap is provided between an inner wall surface of the hood opposite to the intake port and an outer wall surface of the intake duct. An intake duct formed, wherein a tongue is provided in the gap to open and close the gap by an intake negative pressure of an engine.