JP2001280311A - Duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a duct for inhibiting the separation of an air flow at a bent portion and the loss of suction pressure and reducing the noises of the air flow. SOLUTION: The duct 13 having a bent portion 14 comprises a number of dimples 15 provided in the inner face of the bent portion 14 having a smaller radius of curvature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a duct. More specifically, the present invention relates to a duct that prevents fluid separation at a bent portion of a duct having a bent portion such as an intake duct or an exhaust duct of an automobile.

[0002]

2. Description of the Related Art A conventional intake duct 1 for an automobile engine is shown in FIG. In this embodiment, an outlet 2 connected to an intake manifold and an elliptical inlet 3 connected to an air cleaner are connected by a pipe 4 bent at 90 °.

[0003]

In the above-mentioned conventional duct, since the pipe 4 is largely bent, as shown in the intake flow diagram of FIG. 4, the intake flow is separated at the bent portion 5 and the intake is disturbed. In addition, there is a problem that a dead water region of the intake flow is formed, and the intake pressure loss is deteriorated. There is also a problem that airflow noise is generated due to turbulence of intake air.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to realize a duct capable of suppressing separation of an airflow at a bent portion, suppressing an intake pressure loss and reducing an airflow noise.

[0005]

According to a first aspect of the present invention, in a duct having a curved portion, a large number of dimples are provided on an inner surface of the curved portion having a smaller radius of curvature. . A second aspect is characterized in that the dimple 15 is a spherical concave portion.

By adopting this configuration, it is possible to obtain a duct that suppresses separation of airflow at a bent portion, suppresses intake pressure loss, and reduces airflow noise.

[0007]

FIG. 1 is a view showing an embodiment of a duct according to the present invention. FIG. 1 (a) is a front view, and FIG.
FIG. 3C is a cross-sectional view taken along line b, and FIG. In this embodiment, an elliptical inlet 11 is provided at one end of a pipe 10 bent at 90 ° as shown in FIGS. 7A and 7B, and an outlet 12 is provided at the other end. In the duct 13 provided, the inner surface of the bent portion 14 of the pipe 10 having the smaller radius of curvature is provided on the inner surface as shown in FIG.
A large number of dimples (spherical depressions) 15 are provided.

In the present embodiment having the above-described structure, when gas flows from the inlet 11 to the outlet 12, the dimple 1 is formed on the inner surface of the curved portion 14 having the smaller radius of curvature.
By 5, the separation of the airflow is suppressed, and the airflow flows while drawing a smooth streamline. Thereby, the intake pressure loss is suppressed and the airflow noise is also reduced.

[0009]

EXAMPLE As an experimental sample, an inner diameter d = 80 m as shown in FIG.
The length of 90 m bent at 90 °, L ₁ = L ₂ = 150
A polypropylene pipe 16 having a diameter of 5 mm and a depth of about 1 mm is attached to the inner surface of the portion 17 having a smaller curvature radius of 90 ° by using a polypropylene pipe 16 having a diameter of 5 mm and a depth of 1 mm. About 100 concave portions (dimples) 19 were formed at random.

[0010] The above-mentioned sample was subjected to an engine output of 40
2 which is the flow rate of air consumed at 00 to 5000 rpm.
At 25 g / sec, the pressure loss was measured. For comparison, a pipe having the shape shown in FIG. 2 and having no dimple was also measured. The test result shows that the sample having no dimple but having a pressure loss of 179 mmH ₂ O was 1 in the sample of the present invention.
The pressure was 65 mmH ₂ O, and a decrease in pressure loss was confirmed.

[0011]

According to the duct of the present invention, since a large number of dimples are provided on the inner surface having a smaller radius of curvature at a portion bent at 90 °, separation of airflow at a bent portion is suppressed by the dimples. Thus, it is possible to suppress the intake pressure loss and reduce the airflow noise. Note that the present invention can be implemented as long as the duct (pipe) through which fluid flows inside the intake duct for the engine, the duct for the air conditioning, and the other.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a duct of the present invention,
(A) is a front view, (b) is a cross-sectional view taken along line bb of (a), and (c) is an enlarged view of a portion C of (b).

FIG. 2 is a diagram for explaining a sample in an example of the present invention.

FIG. 3 is a perspective view showing a conventional duct.

FIG. 4 is an intake flow diagram of the duct shown in FIG. 3;

[Explanation of symbols]

 10, 16: Pipe 11: Inlet 12: Outlet 13: Duct 14, 17: Bent 15, 19: Dimple 18: Clay

Claims (2)

[Claims] 1. A duct (13) having a bent portion, wherein a large number of dimples (15) are provided on an inner surface of the bent portion (14) having a smaller radius of curvature. 2. The duct according to claim 1, wherein the dimples are spherical recesses.