JPH02303980A - Under floor structure of automobile - Google Patents

Abstract

PURPOSE:To obtain strong down force with vortex generated in a recessed part by forming the recessed part, in which an edge part is placed in a diagonal direction for the direction of air stream line at the time of running of an automobile, in a lower surface of an under floor for covering a lower surface of the automobile. CONSTITUTION:A lower surface of a car body 3 in an automobile 1 is coated with an under floor 5, further it is flatly formed, while each opening 12, 14, which respectively communicates with each wheel house 11, 13 of front and rear wheels 7, 9, is formed. A recessed part 17 is formed between the opening 12 for the front wheel 7 and both sides in a front apron 15, in the lower surface of the under floor 5. While an under floor 17a of the recessed part 17 is arranged in the upper of a lower end 15a in the front apron 15, and an edge part of the recessed part 17 is formed by this lower end 15a. Further both side parts of the front apron 15 are formed in a curved surface shape while so as to provide a predetermined tilt angle alpha for an advancing direction of the automobile.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention J (Field of Industrial Application) This invention relates to an underfloor structure of an automobile for improving the steering stability of the automobile.

(Prior Art) Conventionally, as an underfloor structure of an automobile that actively incorporates aerodynamic improvements, for example, Japanese Patent Application Laid-Open No. 62-28307
Figures 14 and 15 similar to those described in Publication No. 5
There is something like the one shown in the figure.

The underfloor structure of this car is underfloor 1.
01 is formed substantially flat, and the inner portions of the left and right front wheels 103 are formed by a curved convex shape portion IQ5, which reduces the air resistance of the vehicle during driving and also increases the shape of the shape portion 105. The aim is to generate aerodynamic force (hereinafter referred to as downforce) that presses the vehicle against the road surface through the action of the diffuser.

(Problem to be Solved by the Invention) However, in such a conventional underfloor structure, downforce is obtained by the action of the diffuser of the shaped portion 105.
It was not possible to expect sufficient downforce.

Therefore, the object of the present invention is to provide an underfloor structure for an automobile that can apply a strong downforce to an automobile traveling at RB speed and dramatically improve the steering stability during high-speed driving.

[Structure 1 of the Invention (Means for Solving Problem 01) In order to achieve the above object, the present invention covers the lower surface of an automobile with an underfloor, forms this underfloor substantially flat, and provides a A recessed portion is formed whose edge is diagonal to the air flow direction during travel.

(Function) According to the above configuration, a vortex is generated in the concave portion of the underfloor of an automobile traveling at high speed, and a strong downforce acts on the lower surface of the underfloor from the negative pressure caused by this vortex.

(Example) Examples of the present invention will be explained below based on the drawings.

FIG. 1 shows a perspective view of a vehicle having an underfloor structure according to an embodiment of this invention, as viewed from the 1 side.

First, to explain the structure, the lower surface of the vehicle body 3 of the Hakujinshi 1 has an underfloor 5-Q'm made of steel plates, etc., and this underfloor 5 is formed almost flat, and the front wheels 7 and the rear wheels 9 An opening 12. which communicates with the Φ-wheel house 11.13.
It is equipped with 14.

On the underside of Shinki Under 70A5, there is 17 of IYi ring 7 river.
Between 1D12 and both sides of the front apron 15,
A recess 17 as shown in FIGS. 2 and 3 is provided. The underfloor 17a of this concave portion 17 is located above the lower GW 15a of the front nib [15] T=fi10v. Therefore, the lower end 15a of the goblon 15 constitutes the edge of the recess 17.

The apron 15 has curved sides on both sides in the vehicle width direction, and is configured such that the average inclination angle of the tangent or the inclination angle of the tangent at the central part in the width direction is α with respect to the traveling direction of the automatic rn1. .

Next, the effects of the above to actual examples will be explained.

No. 4fj4 shows an enlarged view of the area around the grooved underfloor 178. Since Jt3, the flow line direction a of the air around this grooved underfloor 17a is generally along the traveling direction of the automobile 1. has a slight angle Iα). On the other hand, since the front end of the recessed underfloor 17a has an average inclination angle α with respect to the streamline direction a, the air flowing through the recessed underfloor 17a has a spiral shape as shown in FIG. A vortex is formed.

This spiral swirl is formed as follows.

In other words, (as shown in Figure 82I5), (as shown in ω, the air flow in the !+1 underfloor front end region 1i119 in the vehicle width direction passes under both sides 115a of the front apron 15 and crosses over the front end region 1419. This is due to the fact that the flow that has overcome the step tries to flow along the object again. Therefore, the region 21 on the streamline extension line is compared to This is a small negative pressure area.

On the other hand, the IyJ end region 19 of the recess underfloor 17a
For example, the air flow in the rear end outer peripheral area Liff 123 of the recessed underpants 1]a 17a is
5, the area 41 is a relatively thick negative pressure area because it has just gotten over the lower end 15a.

Therefore, the air on the surface of the region 21 on the streamline extension line where the pressure is relatively high is drawn toward the surface of the region 23 outside the intrusion edge, and the air flows as if being drawn in there. Therefore, the air flow (
In combination with the flow following the streamline direction a), a spiral flow b is formed.

The spiral vortex thus formed in the recessed underfloor 17a has a strong negative pressure and provides a large downforce to the surface of the recessed underfloor 17a.

FIG. 6 shows experimental data comparing aerodynamic characteristics that vary depending on the shape of the underfloor of the front portion of an automobile using the front wheel lift coefficient CL[=.

However, as shown in Fig. 7(a), 8 shown in Fig. 6 is a case where a flat underfloor 5 is provided at the front part, and no vortex is formed at all, and the front wheel lift coefficient CLF
is positive, and no downforce is generated. B shown in Fig. 6 is a case where there is no underfloor in the front part as shown in Fig. 7 (b). It is not formed and becomes a stagnation area, and the front wheel lift coefficient CLF becomes mica, but no downforce can be expected.

On the other hand, C shown in FIG. 6 is a case where a recessed underfloor 17a is formed in the front part as shown in FIG. The coefficient Ctr becomes significantly negative, and a strong downforce acts.

Therefore, the downforce acting on the underpants [1a 17], that is, the downforce acting on the vehicle, increases the ground contact force of the vehicle traveling at high speed, thereby making it possible to steadily improve the maneuverability of the vehicle. Furthermore, since the ground contact force on the front wheel side is relatively increased, reliable driving force can be obtained with front wheel drive. There is no complicated curved part unlike when configuring a diffuser, and manufacturing is easy. In particular, since the coplon 15 is used to form the edge of the recess 17 in the flon 1, the structure is further simplified.

According to this embodiment, for example, as shown in FIG. 8, in contrast to a so-called front spoiler that obtains downforce by lowering the ground height of the apron 15, the apron 15 can be lowered without lowering the ground height as shown in FIG. Since the force can be obtained, the possibility of interference with the road surface can be reduced1.Also, when adjusting downforce, it is common to adjust the ground height using a movable front spoiler. , as shown by D in FIG. 9, when adjusting the height T of the movable front spoiler, the downforce changes greatly with a single Kt of 11111, whereas according to the underfloor structure according to this embodiment, the downforce changes significantly with Ir11. The downforce can be easily adjusted by changing the height of the apron 15 relative to the lower end 15a as shown by F in FIG.

FIG. 10 is a perspective view of an automobile equipped with an underfloor structure according to another embodiment of the present invention, viewed from below. Note that the same elements as those in the above-described embodiments are given the same reference numerals and their explanations will be omitted.

In this embodiment, as shown in FIGS. 11 and 12,
The recessed portion 27 is disposed on the inner side in the vehicle width direction of one night sill on both sides of the vehicle body 3, approximately within a range from the center of the vehicle body 3 in the longitudinal direction to the intrusion end. Underfloor 27a of this recess 27
is located several tens of degrees above the lower surface of the underfloor 5 in the crotch area. .

Next, the effects of this embodiment will be discussed.

FIG. 13 shows an enlarged view of the area around the recess 27, and the air flow around the recess 27 is in a streamline direction a that goes from the outside of the vehicle 1 in the vehicle width direction to the inside diagonally rearward. This is true for vehicles with low minimum ground clearance when traveling at high speeds)
[This is because the air on the lower surface of 1A is exhausted and the pressure in this area is lower than that on the side of the Φ body, so the air on the side comes around to the lower surface of the floor. In contrast, the edge 27 of the recess 27
b is formed at an inclination angle β with respect to the streamline direction a. In this way, the edge 2
When 7b is formed to have a deep color β, the air flowing through the recess 27 will have a spiral vortex as shown in FIG. 131, based on the same principle as in the previous embodiment.

The spiral vortex formed in the recessed underfloor 27 in this manner exerts a strong negative pressure, giving a large downforce to the surface of the recessed underfloor 27a.

Therefore, as in the case of the second embodiment, it is possible to increase the tire ground contact force of an automobile traveling at high speed and improve the steering stability. In addition, since the ground contact force on the rear wheel 9 side is relatively increased, the rear wheel drive
Reliable drive can be obtained in J cars.

In this embodiment, the direction of the edge 27b of the recess 27 is parallel to the traveling direction of the automobile 1, but if the direction is oblique to the streamline direction a of the air, the direction of the edge 27b of the recessed portion 27 is parallel to the traveling direction of the automobile 1. It may have a deep color.

[Effects of the Invention] As is clear from the explanation of the twins, according to the structure of the present invention, a large downforce is applied to a car traveling at high speed by generating a vortex flow, thereby reducing the speed of the vehicle during high speed driving. This significantly improves handling stability.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an automobile equipped with an underfloor drawing according to an embodiment of the present invention viewed from below, FIG. 2 is a view of the front half of the underfloor viewed from below, and FIG. Fig. 2 is a sectional view taken along the line ■-■; Fig. 4 is an enlarged view of the area around the recess;
Figure e), (ω is an explanatory diagram showing the air flow in the recess, Figure 6 is a diagram showing experimental data comparing the aerodynamic characteristics that change depending on the shape of the underfloor of the front section of automatic 11 using the front wheel lift coefficient, Figure 7 Figures (a); (b) and (c) show the shape of the underpants [17] in the front part of an automobile, Figure 8 is a schematic diagram of a front spoiler, and Figure 9 is a front spoiler and an embodiment of the present invention. 10 is a perspective view of an automatic 11 equipped with an underfloor hM"L according to another embodiment of the present invention, viewed from below, and FIG. Figure 12 is a view of the rear half of
A sectional view, FIG. 13 is an enlarged view of the area around the recess, FIG. 14 is a view of the front half of the underfloor according to the conventional example as seen from F, and FIG. 15 is a sectional view taken along the line Xv-Xv in FIG. 14. be. 1... Own) J car 3... Mid-term rest 5... Underfloor 15... Nib [1 n 17.27...
Concave Agent Patent Attorney Hide Miyoshi 7.27...Flyer Figure 1 Figure 2 Ward 3 $4 Figure 5 (o) Figure 5 (bl + Figure 6 Figure 8 Portion 10) Figure 12 Figure 13 Figure 15

Claims (3)

[Claims] (1) The lower surface of the automobile is covered with an underfloor, the underfloor is formed substantially flat, and the lower surface of the underfloor is provided with a recess whose edge is diagonal to the direction of air flow lines during driving. Characteristic underfloor structure of automobiles. (2) The underfloor structure of an automobile according to claim 1, wherein the recessed portion is provided on the rear side of both sides of the front apron having an oblique angle with respect to the direction of movement of the automobile, and the edge portion is provided on the rear side of both sides of the front apron. An underfloor structure of an automobile characterized by being composed of. (3) The underfloor structure of an automobile according to claim 1, characterized in that the recess is provided on the inner side of the side sill surface in the vehicle width direction in a range from approximately the center in the longitudinal direction of the vehicle body to the rear end. Automotive underfloor structure.