JP2010280267A - Grille structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grille structure which can prevent generation of abnormal sound by air current and reduce manufacturing cost. <P>SOLUTION: In the grille structure, a step surface 11 is formed on an outer peripheral surface 8G of a fin 8. The step surface 11 is directed to an upstream side of the air current flowing toward the fin 8 to prevent the generation of abnormal sound by the air current. The fin 8 is molded by a molding die, and the step surface 11 is formed by a divided surface of the molding die to form a mold parting line S. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a grill structure provided with fins.

The grill structure is provided in an automobile, a motorcycle, and other moving bodies, and air flows around the fins as they travel.
Conventionally, in the grill structure described above, as shown in FIGS. 9 and 10, the outer periphery of the fin 8 is in a state where the step surface 11 forming the parting line S of the fin 8 faces the downstream side of the airflow (the vehicle rear side Rr). 9 is a cross-sectional view in a direction perpendicular to the longitudinal direction of the fin, and FIG. 10 is an enlarged cross-sectional view of a portion D in FIG. It is a figure).
However, according to this structure, there is a problem that abnormal noise such as wind noise due to airflow is likely to occur as described below.

  That is, as shown in FIG. 10, the boundary layer 14 is generated on the outer peripheral surface 8 </ b> G of the fin 8 that is in contact with the air flow, and the vortex 15 is generated inside the boundary layer 14. Then, when the vortex 15 inside the boundary layer 14 passes through a region where the pressure of the airflow changes abruptly, such as the stepped portion 16 of the fin 8 or the rear end of the fin 8, the vortex 15 is collapsed. Abnormal noise and pressure waves are generated. In addition, the pressure wave is transmitted to the upstream side (the vehicle front side Fr), the generation of the vortex 15 is promoted, and the vortex 15 is generated / collapsed again. Will occur. 9 and 10, the symbol A is the direction in which the airflow flows.

  In order to solve this problem, as disclosed in Patent Document 1, there has been a grill structure in which the dividing lines of the fins are formed in the longitudinal direction of the fins in the vehicle longitudinal direction. Thereby, the generation position of the vortex is shifted in the front-rear direction of the fin, and the effect of canceling the vortex is increased to prevent the generation of abnormal noise due to the airflow.

Japanese Patent No. 3575189

However, according to the technique of the above-mentioned patent document 1, since the dividing line of the fin is formed by shifting the fin in the longitudinal direction of the vehicle in the longitudinal direction of the vehicle, the structure of the fin is complicated and the manufacturing cost is high. .
An object of the present invention is to provide a grill structure that can prevent the generation of abnormal noise due to airflow and can reduce the manufacturing cost.

The feature of the present invention is that
A grill structure in which a step surface is formed on the outer peripheral surface of the fin,
The step surface is directed to the upstream side of the airflow flowing toward the fins to prevent abnormal noise due to the airflow. (Claim 1)

That is, as shown in FIGS. 4 and 5, since the step surface 11 facing the upstream side of the airflow is formed on the outer peripheral surface (surface) 8G of the fin 8, the airflow is received by the step surface 11 and the airflow The direction of the main stream is bent in the direction away from the outer peripheral surface 8G of the fin 8 (outside). In FIG. 5, symbol A is the direction in which the airflow flows.
At this time, the shape of the boundary layer 14 of the airflow collapses and swells away from the outer peripheral surface 8G, so that the vortex 15 inside the boundary layer 14 cannot maintain the shape. The broken line in FIG. 5 shows a state in which the shape of the vortex 15 changes and swells away from the outer peripheral surface 8G.
That is, the vortex 15 receives a force from the step surface 11 toward the upstream side of the airflow, and the length (diameter) of the vortex 15 in the direction in which the airflow flows is short and the vortex 15 in the direction orthogonal to the direction in which the airflow flows. The length (diameter) is longer.
As a result, the vortex 15 inside the boundary layer 14 tends to disappear before the position where the vortex flow 15 moves away from the outer peripheral surface 8G or reaches the region where the pressure of the airflow rapidly changes such as the rear end of the fin 8. It is difficult to generate abnormal noise. In this way, the generation of noise due to the airflow is prevented by the step surface 11.
In addition, it is not necessary to shift the fin parting line in the longitudinal direction of the vehicle in the longitudinal direction of the fin. Compared to the conventional structure in which the fin parting line is shifted in the longitudinal direction of the fin in the longitudinal direction of the vehicle, The structure can be simplified and the manufacturing cost can be reduced.

In the present invention,
The fin is molded with a mold;
If the step surface is formed by a dividing surface of the mold to form a parting line, the following effect can be obtained. (Claim 2)

  The structure of the mold can be simplified as compared with the structure formed by shifting the fin parting line in the longitudinal direction of the grille in the longitudinal direction of the vehicle as in the prior art. In addition, the step surface that forms the parting line is configured as a step surface that faces the upstream side of the airflow, and this step surface prevents the generation of noise due to the airflow. Compared with the case of forming on the outer peripheral surface of the fin, the structure of the mold can be simplified. As a result, the manufacturing cost can be reduced. (Claim 2)

In the present invention,
The fin portion on the upstream side of the airflow with respect to the step surface is formed in a taper shape spreading toward the downstream side of the airflow in a cross section in a direction orthogonal to the longitudinal direction of the fin,
The step surface is substantially orthogonal to the direction in which the airflow flows,
If the fin portion on the downstream side of the airflow with respect to the step surface is formed in a rectangular shape along the direction in which the airflow flows in the cross section in the direction perpendicular to the longitudinal direction of the fin, the following effects are exhibited. Can do. (Claim 3)

The fin portion on the upstream side of the airflow from the step surface is formed in a taper shape that extends toward the downstream side of the airflow in a cross section perpendicular to the longitudinal direction of the fin. The boundary layer of the airflow formed on the outer peripheral surface (surface) of the fin portion can be easily aligned with the outer peripheral surface of the fin portion.
Since the step surface is substantially orthogonal to the direction in which the airflow flows, for example, the airflow is more reliably generated at the step surface than when the step surface is inclined with respect to the direction in which the airflow flows. The direction of the main stream of the airflow can be easily bent in the direction away from the outer peripheral surface (surface) of the fin (outside).
Thereby, the shape of the boundary layer of the airflow can be easily broken so that the vortex inside the boundary layer cannot maintain the shape. The vortex inside the boundary layer can be easily extinguished before reaching the region where the pressure of the airflow changes abruptly, such as the rear end of the fin, and noise can be made less likely to occur. (Claim 3)

In the present invention,
With the grill structure according to any one of claims 1 to 3 provided in a front bumper of an automobile, it is possible to prevent the generation of abnormal noise that occurs as the automobile travels. (Claim 4)

According to the present invention,
It was possible to provide a grille structure that can prevent the generation of abnormal noise due to airflow and that can reduce the production cost.

The perspective view which shows the front part structure of a vehicle Enlarged perspective view of part B in FIG. AA sectional view of FIG. Fin longitudinal section FIG. 5 is an enlarged cross-sectional view of a portion C in FIG. Longitudinal section showing fins and mold Sectional drawing which shows 1st another embodiment Sectional drawing which shows 2nd another embodiment Diagram showing conventional technology FIG. 10 is an enlarged cross-sectional view of a portion D in FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 3, an upper grill 4 and a lower grill 5 are separately attached to a pair of upper and lower outside air introduction openings 2 and 3 of a front bumper 1 to constitute a grill structure of an automobile.

  The lower outside air introduction opening 3 of the front bumper 1 is formed in a horizontally long rectangular shape in the lower half of the front bumper 1, and the upper outside air introduction opening 2 is formed in a horizontally long rectangular shape in the upper half of the front bumper 1. Is formed. The left and right ends of the lower half and the upper half of the front bumper 1 are bent toward the vehicle rear side Rr, and the upper half of the front bumper 1 is positioned on the vehicle rear side Rr as it is above the lower half. It is bent and inclined.

  The upper half of the front bumper 1 has a pair of left and right headlamp mounting notches 6 located on both sides of the upper outside air introduction opening 2, and the lower half of the front bumper 1 has each headlamp. It has a pair of left and right fog lamp mounting holes 7 located below the mounting notch 6.

  As shown in FIG. 2, the upper grill 4 is configured by combining fins 8 extending in the vehicle width direction and fins 8 extending in the vehicle vertical direction in a lattice pattern, and the lower grill 5 is open to the vehicle rear side Rr. The character-shaped members 9 are combined in a lattice shape. The upper grill 4 and the lower grill 5 are each attached to the front bumper 1 with screws.

  As shown in FIG. 6, the fin 8 is a resin molded product molded by a molding die 10 including a front die 12 and a rear die 13. The upstream side (vehicle front side Fr) of the airflow flowing toward the fin 8 is directed to the center in the vehicle longitudinal direction of the outer peripheral surface 8G of the fin 8 (fin 8 along the vehicle width direction and fin 8 along the vehicle vertical direction) A step surface 11 for preventing the generation of abnormal noise due to airflow is formed over the entire circumference of the outer peripheral surface 8G.

  The step surface 11 is formed by a dividing surface 12M (corresponding to a dividing surface of the molding die) of the front mold 12 that is abutted against the dividing surface 13M of the rear mold 13 to form a parting line S. In the present embodiment, the length (height) L of the step surface 11 in the cross section in the direction orthogonal to the longitudinal direction of the fin 8 is 0.2 mm (not limited to this value). Since the length (height) L (see FIG. 5) of the step surface 11 is a small value such as 0.2 mm, it is possible to suppress the step surface 11 from being a resistance to travel of the automobile.

  The fin portion 8A on the upstream side of the airflow from the step surface 11 (hereinafter referred to as “front fin portion 8A”) is downstream of the airflow (the vehicle rear side) in the cross section in the direction perpendicular to the longitudinal direction of the fin 8. Rr) is formed in a tapered shape that gently spreads toward the front, and the end portion of the vehicle front side Fr is formed in an arc shape (an arc shape in cross section). The step surface 11 is substantially orthogonal to the direction in which the airflow flows (vehicle longitudinal direction).

Further, the fin portion 8B on the downstream side of the airflow from the step surface 11 (hereinafter referred to as “rear fin portion 8B”) follows the direction in which the airflow flows in the cross section in the direction orthogonal to the longitudinal direction of the fin 8. The outer peripheral surface 8G of the fin portion 8B on the rear side extends in a straight line from the outer peripheral edge of the step surface 11 (the outer peripheral edge forming the parting line S) to the vehicle rear side Rr. The front fin portion 8A and the rear fin portion 8B have substantially the same length in the vehicle front-rear direction.
A boundary portion between the outer peripheral surface 8G of the front fin portion 8A and the rear fin portion 8B is formed at a substantially central position in the vehicle front-rear direction of the outer peripheral surface 8G, and is behind the outer peripheral surface 8G of the front fin portion 8A. The outer peripheral surface 8G of the fin portion 8B protrudes outward, so that a step portion is formed at the boundary portion. The step portion is formed along the width direction of the vehicle or the longitudinal direction of the fin 8 and the step is about 0.2 mm as described above. On the front fin portion 8A side of the step portion, a step surface 11 is disposed continuously to the outer peripheral surface 8G of the front fin portion 8A.
The step surface 11 is effective to be a surface substantially perpendicular to the airflow direction, but is not limited to a surface perpendicular to the airflow direction. A surface inclined with respect to the flow direction of the air flow may be used as long as it is peeled off from 8G or increases the pressure in front of the stepped portion (upstream side of the air flow). In addition, in consideration of moldability in manufacturing, it is desirable to form a step portion at a substantially central position in the vehicle front-rear direction of the outer peripheral surface 8G. Setting the length of the fin portion 8B on the rear side is also effective in preventing the generation of abnormal noise that occurs as the automobile travels.

  By the way, as shown in FIG. 9, the stepped surface 11 forming the parting line S of the fin 8 is formed on the outer peripheral surface 8G (front surface) of the fin 8 so as to face the downstream side of the airflow (vehicle rear side Rr). However, the conventional grill structure has a problem that abnormal noise such as wind noise due to airflow is likely to occur as described below.

  That is, as shown in FIG. 10, the boundary layer 14 of the airflow flowing along the outer peripheral surface 8G is generated on the outer peripheral surface 8G of the fin 8 in contact with the air current, and the vortex 15 is generated inside the boundary layer 14. Then, when the vortex 15 inside the boundary layer 14 passes through a region where the pressure of the airflow changes abruptly, such as the stepped portion 16 of the fin 8 or the rear end of the fin 8, the vortex 15 collapses and simultaneously with the collapse of the vortex 15. Abnormal noise and pressure waves are generated. Further, the pressure wave is transmitted to the upstream side (the vehicle front side Fr), the generation of the vortex 15 is promoted, the vortex 15 is generated / collapsed again, and the phenomenon that the abnormal noise and the pressure wave are generated is repeated and the abnormal noise is intermittently generated. Will occur.

On the other hand, according to the present invention, as shown in FIGS. 4 and 5, the step surface 11 facing the upstream side of the airflow is formed on the outer peripheral surface (surface) 8 </ b> G of the fin 8. It is received by the surface 11 and the pressure of the airflow at the part increases, and the direction of the mainstream of the airflow is bent in the direction away from the outer peripheral surface 8G of the fin 8 (outside). In FIG. 5, symbol A is the direction in which the airflow flows.
At this time, the shape of the boundary layer 14 of the airflow collapses and swells away from the outer peripheral surface 8G, so that the vortex 15 inside the boundary layer 14 cannot maintain the shape. The broken line in FIG. 5 shows a state in which the shape of the vortex 15 changes and swells away from the outer peripheral surface 8G.
That is, the vortex 15 receives a force from the step surface 11 toward the vehicle front side Fr (upstream side of the airflow), the length (diameter) of the vortex 15 in the vehicle front-rear direction (airflow direction) is short, and the vehicle The length (diameter) of the vortex 15 in the direction orthogonal to the front-rear direction (the direction in which the airflow flows) is long.
As a result, the vortex 15 inside the boundary layer 14 tends to disappear before reaching the region where the pressure of the airflow changes abruptly (the pressure decreases) such as the rear end of the fin 8 and cannot reach the region. , Noise is less likely to occur. In this way, the generation of noise due to the airflow is prevented by the step surface 11.
The inventor has confirmed by experiments that abnormal noise is less likely to occur if the length L of the stepped surface 11 in the longitudinal section is 0.1 mm to 1 mm.

[Another embodiment]
(1) As shown in FIG. 7, the stepped portion 16 having the stepped surface 11 may be formed in a flange-like shape at the intermediate portion in the longitudinal direction of the fin 8. The fin portion 8B on the rear side is formed in a rectangular shape along the direction in which the airflow flows in the cross section in the direction orthogonal to the longitudinal direction of the fin 8. Further, in the cross section in the direction perpendicular to the longitudinal direction of the fin 8, the thickness of the rear fin portion 8B is thinner than the thickness of the front fin portion 8A (thickest portion).
As a result, the fin 8 can be reduced in weight as compared with the structure in which the thickness of the rear fin portion 8B is thicker than the thickness of the front fin portion 8A (thickness of the thickest portion). Cost can be reduced.

(2) As shown in FIG. 8, a plurality of the step surfaces 11 may be provided at intervals in the airflow direction.
The fin portion 8A on the upstream side of the airflow with respect to the step surface 11 on the front side Fr of the vehicle has a taper that gradually spreads toward the downstream side (vehicle rear side Rr) of the airflow in a cross section in a direction orthogonal to the longitudinal direction of the fins 8. The end portion of the vehicle front side Fr is formed in an arc shape (an arc shape in cross section).
The fin portion 8C in the middle in the vehicle longitudinal direction is formed in a rectangular shape along the direction in which the airflow flows in the cross section in the direction perpendicular to the longitudinal direction of the fin 8, and the outer peripheral surface 8G of the fin portion 8C in the middle in the vehicle longitudinal direction is A straight line extends from the outer peripheral edge of the step surface 11 on the vehicle front side Fr to the vehicle rear side Rr.
The fin portion 8B on the vehicle rear side Rr is formed in a rectangular shape along the direction in which the airflow flows in the cross section in the direction orthogonal to the longitudinal direction of the fin 8, and the outer peripheral surface 8G of the fin portion 8B on the vehicle rear side Rr is A straight line extends from the outer peripheral edge of the step surface 11 on the vehicle rear side Rr to the vehicle rear side Rr.

(3) In the above embodiment, the fins 8 are formed long in the vehicle width direction or the vehicle up-down direction. However, the fins 8 may be formed long in a direction inclined with respect to the horizontal direction.

(4) In the above embodiment, the automobile grill structure has been described as an example. However, the present invention is not limited to the automobile grill structure, and is also applied to a grill structure of a moving body such as a motorcycle, a ship, and a water bike. You can also.

DESCRIPTION OF SYMBOLS 1 Front bumper 8 Fin 8A Fin part 8B of the upstream side of an airflow rather than a step surface Fin part 8G of the downstream side of an air flow rather than a step surface Fin outer peripheral surface 10 Mold 11 Step surface 12M Mold split surface S Mold dividing line

Claims (4)

A grill structure in which a step surface is formed on the outer peripheral surface of the fin,
The said step surface faces the upstream of the airflow which flows toward the said fin, The grille structure which prevents generation | occurrence | production of the noise by the said airflow. The fin is molded with a mold;
The grill structure according to claim 1, wherein the step surface is formed by a dividing surface of the mold to form a parting line. The fin portion on the upstream side of the airflow with respect to the step surface is formed in a taper shape spreading toward the downstream side of the airflow in a cross section in a direction orthogonal to the longitudinal direction of the fin,
The step surface is substantially orthogonal to the direction in which the airflow flows,
The grill according to claim 1 or 2, wherein the fin portion on the downstream side of the airflow from the step surface is formed in a rectangular shape along a direction in which the airflow flows in a cross section in a direction perpendicular to the longitudinal direction of the fin. Construction   The grill structure as described in any one of Claims 1-3 provided in the front bumper of a motor vehicle.

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