JP2000038158A - Roof structure of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To weaken the force of the air current colliding with the tip of a back door by providing a step made relatively higher on the roof panel side in the closed state of the back door on the parting section between the roof panel and the back door, and providing a tip low section lower than the rear end of the roof panel at the front end of the back door. SOLUTION: A back door 12 is openably fitted to a roof panel 11 via two hinges on the right and left. A tip low section 15 having a step D only on the parting section between the back door 12 and the roof panel 11 in the closed state is formed. The step D between the roof panel 11 and the tip low section 15 is set to about 3 mm or above in size. This roof structure functions to lift the air current peeled off at the rear end section 11a of the roof panel 11 upward than the position of the tip low position 15 at the front end section 12a of the back door 12. The air current colliding with the tip low section 15 at the front end of the back door 12 is weakened, thus aerodynamic noise (cavity sound) can be reduced and suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roof structure of an automobile, and is particularly suitable for reducing and suppressing aerodynamic noise (cavity sound) generated when the vehicle is running.

[0002]

2. Description of the Related Art In a conventional automobile roof structure, FIG.
As shown in FIG. 13 and the rear end portion 1a of the roof panel 1,
And the front end 2a of the back door 2, which is attached to the roof panel 1 via a hinge so as to be openable and closable, is substantially flush in the vertical direction. In such an automobile, aerodynamic noise may be generated at the back door 2 and the parting portion 3 of the roof panel 1 which are closed during running. This aerodynamic noise is called cavity noise.

[0003]

However, in the above-mentioned conventional roof structure, as shown in FIG. 14, the airflow AC from the front of the vehicle separates from the rear end 1a of the roof panel 1 at the upstream end of the parting portion 3. Then, it collides with the front end surface of the front end portion 2a of the back door 2 at the downstream end, self-excited vibration occurs at the time of the collision, and noise occurs due to resonance in the closed volume 4 (cavity). In particular, when the separated air flow strongly hits the front end face of the front end 2a of the back door 2, and when viewed as a time-averaged flow, when a stagnation point of the air flow AC occurs near the center of the front end face of the front end 2a, noise is generated. There was a problem of becoming large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and has as its object the flow separated from the rear end of a roof panel collides with the front end of a back door. It is an object of the present invention to provide an automobile roof structure capable of reducing and suppressing cavity noise.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to an automobile roof structure in which a back door is attached to a roof panel via a hinge so as to be openable and closable. The roof panel side is provided with a relatively high step when the back door is in a closed state, and the front end of the back door is lower in height than the rear end of the roof panel. May be provided, and the step may be provided only at a parting portion between the roof panel and the back door between the hinges for attaching the back door, and the entire upper surface of the roof panel may be arranged to be wider than the front end of the back door. May be higher. Also,
In the present invention, an upwardly convex portion may be partially provided only at the rear end of the roof panel, or a molding may be partially provided by being raised only at the rear end of the roof panel.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A roof structure of an automobile according to a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing an automobile to which a roof structure according to a first embodiment of the present invention is applied, FIG. 2 is a longitudinal sectional view taken along line AA in FIG. 1, and FIG. It is a longitudinal cross-sectional view along the B line. Car 11 according to this embodiment
The back door 12 is attached to the roof panel 11 via left and right hinges 13 disposed on the upper surface thereof so as to be openable and closable. The back door 12 is provided at a parting portion 14 between the roof panel 11 and the back door 12. In the closed state of 12, the roof panel 11 side is provided with a relatively high step.

The back door 12 has two hinges 1 on the left and right.
It is attached to the roof panel 11 so as to be openable and closable via the third and third ends 13, and in the closed state, the step D is provided only at the parting part 14 between the mounting hinges 13 and 13 of the back door 12 and the roof panel 11. The lower part 15 is formed. Accordingly, as shown in FIG. 3, the back door 12 has no step at the parting portion 14 on the outer side in the vehicle width direction of the hinges 13, 13, and has a front end that is not inclined and faces the rear end of the roof panel 11 in the vertical direction. There is one side part 16. The back door 12 is dimensioned such that the front end is inclined forward and downward, and the step D between the roof panel 11 and the lower end portion 15 between the left and right hinges 13 is about 3 mm or more in a closed state. Have been.

FIG. 4 is a longitudinal sectional view showing a roof structure according to a second embodiment of the present invention. The back door 12 according to the present embodiment forms a hemming portion 18 as a lower end portion which is bent downward at the tip of the front end portion 12a and dropped below the upper surface of the roof panel 11 to be lower. Are dimensioned so that the step D between the lower end surface of the top panel and the upper surface of the roof panel 11 is 3 mm or more.

FIGS. 5 and 6 are side views for explaining aspects of airflow in the case of the roof structure of the automobile according to the above embodiment. During traveling of the vehicle, the airflow AC along the upper surface of the roof panel 11 is applied to the rear end 1 of the roof panel 11.
Peel at 1a. If there is no step between the front end portion 12a of the back door 12 and the rear end portion 11a of the roof panel 11, or if the step is 2 mm or less, the separated air current is generated by the back door 1
By colliding with the front end surface of the front end portion 12a of the second, self-excited vibration occurs, resonates in the closed volume 4, and aerodynamic noise (cavity sound) is generated.

However, in the roof structure shown in FIGS. 5 and 6, the airflow separated at the rear end 11 a of the roof panel 11 is higher than the position of the lower end 15 or the hemming 18 of the front end 12 a of the back door 12. Acts to push up. As a result, the front lower end portion 15 of the front end of the back door 12
Alternatively, the flow colliding with the hemming portion 18 is weakened, and the self-excited vibration energy is reduced. That is, the time variation of the pressure generated at the time of the collision becomes small, and in the case of the roof structure according to the embodiment of the present invention shown by the broken line in FIG. Is 500-1
The sound pressure level (dB) on the vertical axis in the range of K (10 HZ / 3) is significantly reduced.

FIG. 8 is a schematic side view showing a roof structure according to a third embodiment of the present invention. In this embodiment, the entire upper surface of the roof panel 11 in front of the front end 12a of the back door 12 is
And a position higher than the upper surface of the conventional roof panel 11 indicated by a two-dot chain line by a height h, and the front end 12a of the back door 12 is not inclined as in the conventional case. Roof panel 1
1 has a curved plate portion 21 having a radius of curvature R that follows the substantially flat upper plate portion 20, and the curved plate portion 21 has a descending plate portion 22.
The upper plate portion 20 and a part of the curved plate portion 21 are located at a position higher than the front end portion 12 a of the back door 12.

As a result of a numerical simulation during traveling of the vehicle, in terms of time-averaged flow, in the case of the conventional roof structure, the stagnation point of the flow colliding with the front end portion 2a of the back door 2 in FIG. It occurs slightly downward on the tip surface of 2a. That is, in such a case, the time variation of the pressure generated near the stagnation point becomes large, and the pressure variation resonates in the volume section 4 to generate noise.

On the other hand, in the roof structure according to the third embodiment of the present invention, the rear end portion 11 of the roof panel 11 is provided.
This acts to push the flow separated from the upper side upward from the position of the front end surface of the front end portion 12a of the back door 12.
As a result, the flow colliding with the front end surface of the front end portion 12a of the back door 12 is weakened. That is, the time variation of the pressure generated at the time of the collision becomes small, and the cavity noise is reduced. As a result of the numerical simulation, the position of the stagnation point moves upward from the front end surface of the front end portion 12a of the back door 12 in terms of the time average flow. As a result of an experiment, it was found that the noise level dB in the case of the present invention indicated by the broken line in FIG.

FIG. 10 is a schematic side view showing a roof structure according to a fourth embodiment of the present invention. This roof structure is configured by partially providing an upwardly convex portion 25 only on the rear end portion 11a of the roof panel 11. The protrusion 25
The rear surface of the flat upper surface of the roof panel 11 has a gentle inclined surface 26 with an inclination angle θ continuing through a round surface with a radius r, and a curved surface 27 with a radius of curvature R following the gentle inclined surface 26. The highest protruding height h (step D) from the flat upper surface of the roof panel 11 in the vicinity of the connection between the inclined surface 26 and the curved surface 27.
It is formed so that it becomes. Even in this way, the first to first
The same noise reduction effect as in the third embodiment can be obtained.

FIG. 11 is a schematic side view showing a modification of the fourth embodiment. This roof structure is constructed by raising the roof panel 11 only at the rear end 11a and partially providing a resin molding 30. Resin molding 30
Has a gentle inclined surface 31 having an inclined angle θ and a curved surface 32 having a radius of curvature R, and a maximum protruding height from a flat upper surface of the roof panel 11 near a connection portion between the gentle inclined surface 31 and the curved surface 32. H (step D).

The present invention is not limited to the above embodiment, and various modifications and changes can be made. For example, a metal molding or a ceramic molding may be used instead of the resin molding.

[0017]

According to the present invention, there is provided a parting portion between a roof panel and a back door, wherein a relatively high step is provided on the roof panel side when the back door is closed, and a rear end of the roof panel is provided at a front end of the back door. By lowering the tip lower part, the force of the airflow that collides with the tip of the backdoor is reduced (the stagnation point of the airflow is removed from the tip of the backdoor), and the self-excited vibration energy is reduced, thereby reducing the aerodynamics. This produces an effect that noise (cavity sound) can be reduced and suppressed. The same effect can be obtained even if a step is provided only at the parting portion between the roof panel and the back door between the hinges for attaching the back door, and the entire upper surface of the roof panel may be higher than the front end of the back door. An upwardly convex portion may be partially provided only at the rear end of the roof panel, and a molding may be partially provided by being raised only at the rear end of the roof panel. Can be reduced and suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view showing an automobile to which a roof structure according to a first embodiment of the present invention is applied.

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

FIG. 3 is a longitudinal sectional view taken along line BB of FIG. 1;

FIG. 4 is a longitudinal sectional view showing a roof structure according to a second embodiment of the present invention.

FIG. 5 is a schematic side view for explaining aspects of airflow in the case of the roof structure according to the first embodiment.

FIG. 6 is a schematic side view for explaining aspects of airflow in the case of a roof structure according to the second embodiment.

FIG. 7 is a graph showing a noise reduction effect in the case of the roof structure according to the first and second embodiments.

FIG. 8 is a schematic side view showing a roof structure according to a third embodiment of the present invention.

FIG. 9 is a graph showing a noise reduction effect in the case of a roof structure according to a third embodiment of the present invention.

FIG. 10 is a schematic side view showing a roof structure according to a fourth embodiment of the present invention.

FIG. 11 is a schematic side view showing a modification of the roof structure according to the fourth embodiment of the present invention.

FIG. 12 is a side view of an automobile to which a conventional roof structure is applied.

FIG. 13 is a schematic side view drawn by a dashed line in FIG. 12 and showing a main part in a circle.

FIG. 14 is a schematic side view for explaining an aspect of a separated airflow that causes noise in the case of a conventional roof structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Roof panel 11a Rear end part 12 Back door 12a Front end part 13 Hinge 14 Parting off part 15 Low end part 16 Part of surface 18 Hemming part (Low end part) 21 Curved plate part 25 Convex part 26 Slowly inclined surface 27 Curved surface 30 Resin Mall 31 Slightly inclined surface 32 Curved surface

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsuhisa Morikami 300 Takatsukacho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd. F-term (reference) 3D003 AA16 BB03 CA38 DA17

Claims (6)

[Claims] 1. An automobile roof structure wherein a back door is openably and closably attached to a roof panel via a hinge. The roof panel is provided at a parting portion between the roof panel and the back door when the back door is closed. A roof structure for an automobile, wherein a relatively high step is provided on a side. 2. The roof structure of an automobile according to claim 1, wherein a lower end portion lower than a rear end of the roof panel is provided at a front end of the back door. 3. The automobile roof structure according to claim 1, wherein the step is provided only at a part between the roof panel and the back door between the hinges for attaching the back door. . 4. The roof panel according to claim 1, wherein an entire upper surface of the roof panel is higher than a front end of the back door.
The roof structure of an automobile according to claim 1. 5. The roof structure of an automobile according to claim 1, wherein an upwardly convex portion is provided only at a rear end of the roof panel. 6. The roof structure of an automobile according to claim 1, wherein a molding is provided only on a rear end of the roof panel and partially formed.