JP2021138163A - Vehicular lower vehicle body structure - Google Patents

Abstract

To improve the aerodynamic performance by suppressing occurence of a vortex flow at the rear side of a front wheel under a floor.SOLUTION: A pair of right and left front side floor under covers 19a is provided which extends in the back-and-forth direction at the back side from the position of a front wheel 12 in the vehicle back-and-forth direction, and which forms a part of the lower surface of a vehicle body. A protrusion 61 which extends in the vehicle back-and-forth direction and which protrudes downwardly is formed at a position that divides a region straight-backwardly relative to the front wheel 12, and a rear region located inwardly in the vehicle widthwise direction relative to the front wheel 12 in each front side floor under cover 19a. The protrusion 61 is caused to function as a divider for a slow running wind B that flows straight-backwardly from the front wheel 12 and a fast running wind A that flows along each front side floor under cover 19a, thereby suppressing occurrence of a vortex flow that deteriorates the aerodynamic performance.SELECTED DRAWING: Figure 6

Description

The present invention relates to a vehicle lower body structure such that the aerodynamic performance is good.

The aerodynamic performance at the bottom of the vehicle is improved by rectifying the running wind between the vehicle body and the road surface to reduce resistance.

In Patent Document 1 below, vertical walls projecting downward are provided on the straightening vanes provided on the left and right sides of the floor tunnel in the center of the vehicle width direction, and the traveling wind under the vehicle body is positively converged in the center of the vehicle width direction. A structure for improving aerodynamic performance is disclosed. The shape of the vertical wall is composed of an inclined portion that recedes toward the inside from the outside in the vehicle width direction toward the inside, and an inclined portion that inclines more steeply from the inner end of the inclined portion in the vehicle width direction.

In this structure, since the traveling wind is converged in the center in the vehicle width direction, it is possible to suppress the traveling wind from flowing out to the side of the vehicle body, and as a result, the aerodynamic performance is improved.

Japanese Unexamined Patent Publication No. 2006-298312

However, while the speed of the running wind under the undercover provided on the left and right sides of the floor tunnel is high, the speed is slower behind the front wheels. Therefore, as shown in FIG. 7, a part X1 of the traveling wind X under the undercover 101 flows out to the side due to the influence of the traveling wind Y behind the front wheels 102, and the vortex Z is generated in the portion where the speed difference is present. It may occur and deteriorate the aerodynamic performance.

Therefore, the main object of the present invention is to suppress the generation of vortices behind the front wheels under the floor and improve the aerodynamic performance.

The means for that purpose includes an undercover that extends in the front-rear direction from the position of the front wheels in the front-rear direction of the vehicle to form a part of the lower surface of the vehicle body, and the undercover is fixed to the vehicle body side at the outer end in the vehicle width direction. It is a lower body structure of a vehicle having a fixed edge portion to be formed and a flat plate-shaped main body plate portion located inside the fixed edge portion in the vehicle width direction and below the fixed edge portion. A projecting portion extending in the front-rear direction of the vehicle and projecting downward is formed at the outer edge portion in the vehicle width direction, and the projecting portion projects downward from the lower surface of the main body plate portion at a position closer to the front wheels. It is a lower body structure of a vehicle having a peak portion having the highest protrusion height and being formed so that the protrusion height becomes lower toward the rear from the peak portion.

In this configuration, the projecting portion acts as a partition to prevent a part of the running wind under the undercover from flowing out to the side behind the front wheels. The peak portion having the highest protrusion height among the projecting portions is located closer to the front wheels, and effectively suppresses the air flow that tends to flow out to the side behind the front wheels away from the front wheels.

In one aspect of the present invention, the lower surface of the extension portion extending rearward from the peak portion in the projecting portion is formed in a straight line, and the undercover is in a state where the lower surface of the extension portion is viewed from the side surface of the vehicle. It is preferable to have a fixed configuration so as to be substantially horizontal.

In this configuration, as described above, the aerodynamic performance of the projecting portion is improved, and the lower surface of the extension portion of the projecting portion forming a straight line is horizontal, so that the silhouette of the lower end of the undercover visible from the side surface of the vehicle. (Outline / outer shape) looks horizontal, improving the appearance.

In one aspect of the present invention, it is preferable that the front end portion of the projecting portion is formed with an inclined portion that inclines upward toward the front.

In this configuration, the running wind that hits the front end of the main body plate portion of the undercover is smoothly flowed around the projecting portion by the inclined portion, and the air resistance is reduced.

In one aspect of the present invention, the undercover has a fixed surface portion located above the main body plate portion and fixed to the vehicle body at the front end portion on the outer side in the vehicle width direction, and the fixed surface portion and the main body plate portion. It is preferable that a vertical wall portion is provided to connect the vertical wall portions, and the projecting portion is formed behind the vertical wall portion.

In this configuration, the height of the vertical wall portion standing in front of the projecting portion is suppressed, the increase in air resistance is suppressed, and the appearance can be improved.

According to the present invention, since the protruding portion is provided on the outer edge portion of the main body plate portion in the vehicle width direction, it is possible to suppress the generation of a vortex behind the front wheels under the floor and improve the aerodynamic performance.

Bottom view showing the lower body structure of the vehicle. A perspective view showing a main part. A perspective view showing a main part. Side view of the lower body structure of the vehicle. FIG. 2 is a cross-sectional view taken along the line EE of FIG. A partially enlarged view of FIG. 1 showing an operating state. Bottom view showing the prior art.

An embodiment for carrying out the present invention will be described below with reference to the drawings.

FIG. 1 shows a bottom view of the lower body structure 11 of the vehicle looking up from below, and FIGS. 2 and 3 show perspective views of the main parts thereof. FIG. 2 shows a state in which the lower vehicle body structure 11 is viewed diagonally upward from the rear, and FIG. 3 shows a state in which it is viewed diagonally upward from the front to the rear. The white arrows in the figure are for helping the understanding of the drawing, and "Rr", "Fr", "R", and "L" in the arrows are "rear", "front", and "front" of the vehicle, respectively. Represents "right" and "left". Therefore, the direction connecting "Rr" and "Fr" is the vehicle front-rear direction, and the direction connecting "R" and "L" is the vehicle width direction. The same applies to other figures.

As shown in these figures, the lower vehicle body structure 11 includes a plurality of undercovers that cover the lower surface of the vehicle body and form the lower surface of the vehicle body.

It is the engine undercover 13 that covers the bottom of the engine room (not shown) between the pair of left and right front wheels 12. The rear end of the engine undercover 13 is fixed to the front end of the front subframe 16 connecting the left and right suspensions 15 in front of the floor tunnel 14. The floor tunnel 14 extends in the front-rear direction of the vehicle and accommodates the exhaust system 17.

Behind the front subframe 16, a tunnel undercover 18 and a pair of left and right floor undercovers 19 as undercovers of the present invention are provided.

The tunnel undercover 18 is located in the center in the vehicle width direction and covers only the lower part of the front end portion having the inclined portion 14a (see FIG. 4 which is a side view of the lower body structure 11) in the floor tunnel 14, and the tunnel undercover 18 is covered. The rear end portion 18a is set at a position corresponding to the rear of the inclined portion 14a.

The rear end portion 18a of the tunnel undercover 18 has a pair of left and right fixed surface portions 31 fixed to both ends in the vehicle width direction of the floor tunnel 14, a rear surface wall portion 32 extending upward between the fixed surface portions 31, and a rear surface wall portion. A pair of connecting surface portions 33 for connecting the 32 and the fixed surface portion 31 are provided.

The fixed surface portion 31 is located above the main body portion 34 to be covered and has a flat plate shape. The portion of the main body 34 connected to the front end of the fixed surface portion 31 is composed of an inclined portion 35 that rises diagonally upward toward the rear.

The rear wall portion 32 is located in front of the fixed surface portion 31 in the front-rear direction of the vehicle, and extends upward from the rear end of the main body portion 34. The height of the rear wall portion 32 is set in consideration of the exhaust system 17 provided in the floor tunnel 14. The upper end edge of the rear wall portion 32 has a linear shape having a continuous continuity without unevenness or steps.

The plan view shape of the rear wall portion 32 is a substantially arc shape in which the inner portion in the vehicle width direction is located in front of the rear portion. More specifically, the inner portion in the vehicle width direction located in the front is close to a straight line, and the two side portions in the vehicle width direction are steeper toward the rear.

In the rear wall portion 32 having such a plan view shape, the fixed surface portion 31 is located above the main body portion 34 and has the inclined portions 35 in front of the fixed surface portion 31, so that both ends in the vehicle width direction are formed. , A triangular portion 32a having a substantially triangular shape when viewed from the front of the vehicle is formed. These triangular portions 32a have a shape in which the height increases toward the outside in the vehicle width direction.

The connecting surface portion 33 has a substantially triangular shape on the side surface of the vehicle that connects the triangular portion 32a, which is the outer end portion of the rear surface wall portion 32 in the vehicle width direction, and the fixed surface portion 31.

The ridgeline portion between the connecting surface portion 33 and the fixed surface portion 31, that is, the corner portion extending in the vehicle front-rear direction located inside the fixed surface portion 31 and the inclined portion 35 in the vehicle width direction, is a bead 36 for reinforcement protruding downward. Is formed.

The floor undercover 19 extends in the front-rear direction from the position of the front wheel 12 in the front-rear direction and rearward of the vehicle, and covers both the left and right sides sandwiching the floor tunnel 14. The floor undercover 19 that covers the area between the front wheels 12 and the rear wheels 21 is composed of a front floor undercover 19a that covers a portion close to the front wheels 12 and a rear floor undercover 19b that covers a portion close to the rear wheels 21. Has been done. The rear floor undercover 19b covers the area under the rear seat (not shown) where the fuel tank (not shown) is provided, and is in the front-rear direction of the vehicle as compared with the front floor undercover 19a. The length is short.

The front floor undercover 19a and the rear floor undercover 19b have a fixed edge 51 fixed to the vehicle body side at the outer end in the vehicle width direction and a fixed edge 51 inside the vehicle width direction from the fixed edge 51. It has a flat plate-shaped main body plate portion 52 located below. A plurality of through holes are formed in the fixed edge portion 51, and the fixing edge portion 51 is fixed to the vehicle body side by a fastener.

Further, between the fixed edge portion 51 and the main body plate portion 52, a hanging wall 53 extending in the vertical direction is formed, and the front floor undercover 19a is also formed with the fixed edge portion 54 at the inner end portion in the vehicle width direction. Therefore, the approximate cross-sectional shape of the front floor undercover 19a is an inverted hat type as shown in FIG. 5A and 5B are cross-sectional views taken along the line EE of FIG. 2, in which 25 is an inner member of a side sill, 26 is a floor panel, and 27 is a reinforcing frame for reinforcing the lower end of the floor tunnel 14. The fixed edge 51 on the outer side of the front floor undercover 19a in the vehicle width direction is attached to the inner member 25 of the side sill, and the fixed edge 54 on the inner side in the vehicle width direction is attached to the reinforcing frame 27.

In addition to the fixed edge portions 51 and 54, the front side floor undercover 19a and the rear side floor undercover 19b are appropriately formed with fixing portions necessary for fixing to the vehicle body side. In the figure, 55 is one of them, and is a fixed recess formed at the front end portion of the front floor undercover 19a.

The fixed recess 55 is formed diagonally from the front end to the rear of the front floor undercover 19a, is directly fixed to the vehicle body side by the fastener 56, and has a rod shape bridged with the front subframe 16. It is also fixed with the fixture 57. The fixed recess 55 is inclined outward in the vehicle width direction toward the rear in the front-rear direction of the vehicle.

Of the front end surface of the front floor undercover 19a, the portion 58 inside the vehicle width direction from the fixed recess 55 is hidden behind the front subframe 16, so that the inclination does not have to be lowered as much as the vehicle front-rear direction rearward. .. On the other hand, since the portion 59 outside the fixed recess 55 in the vehicle width direction is a portion directly exposed to the traveling wind, it has a low resistance surface having an inclination that decreases downward toward the rear in the front-rear direction of the vehicle in order to reduce air resistance. doing.

The above-mentioned hanging wall 53 extending in the vertical direction extends straight along the vehicle front-rear direction, and its position in the vehicle width direction is from the inner surface position 12a of the front wheel 12 as shown by the auxiliary line L1 in FIG. Is also inside. That is, the hanging wall 53 exists at a position that separates the region directly behind the front wheels 12 and the rear region inside the front wheels 12 in the vehicle width direction. The outer end of the fixed edge 51 on the outer side in the vehicle width direction is located at a position substantially corresponding to the inner surface position 12a of the front wheel 12.

A projecting portion 61 extending downward in the vehicle front-rear direction at the outer edge portion in the vehicle width direction of the main body plate portion 52 forming the inner side in the vehicle width direction from the hanging wall 53 and forming the lower surface of the front floor undercover 19a. Is formed. The outer side surface of the projecting portion 61 in the vehicle width direction is flush with the hanging wall 53. In other words, there is an outer side surface of the projecting portion 61 in the vehicle width direction on the extension of the hanging wall 53, and there is no such thing as a step between the hanging wall 53 and the projecting portion 61 that distinguishes the two from the appearance. ..

The projecting portion 61 has a shape capable of obtaining a step for suppressing lateral movement of air flowing along the surface (lower surface) of the main body plate portion 52, and the cross-sectional shape of the lower end portion thereof is formed in an arc shape. Has been done. The width of the projecting portion 61 is appropriately set so that the height required for the projecting portion 61 can be obtained.

Since the position of the hanging wall 53 in the vehicle width direction on the inner side surface of the projecting portion 61 in the vehicle width direction is inside the inner surface position 12a of the front wheel 12, as shown by the auxiliary line L2 in FIG. It will be located inside the inner surface position 12a of the front wheel 12.

The projecting portion 61 is not formed from the front end of the front floor undercover 19a, but is formed from a position slightly retracted rearward in the front-rear direction of the vehicle. That is, it is located at the front end portion of the front floor undercover 19a on the outer side in the vehicle width direction and is located inside the hanging wall 53 in the vehicle width direction, above the main body plate portion 52, and is fixed to the vehicle body. A fixed surface portion 62 is provided, and a vertical wall portion 63 that connects the fixed surface portion 62 and the main body plate portion 52 is provided. The vertical wall portion 63 exists in a manner of narrowing the width of the above-mentioned low resistance surface (the portion 59 outside the vehicle width direction from the fixed recess 55) in the vehicle width direction, and the vehicle width direction is closer to the rear in the vehicle front-rear direction. It is gently curved so that it goes out. Regarding the shape of the vertical wall portion 63 vehicle in the vertical direction, it is inclined inward in the vehicle width direction toward the lower side. Behind such a vertical wall portion 63, a projecting portion 61 is formed continuously from the vertical wall portion 63.

The projecting portion 61 has an inclined portion 64 at the front end portion, which is inclined upward toward the front. In other words, the inclined portion 64 has a shape that lowers downward as it goes backward, and may be linear or curved. Behind the inclined portion 64, a peak portion 65 having the highest protruding height protruding downward from the lower surface of the main body plate portion 52 is formed. The portion from the inclined portion 64 to the peak portion 65 is gently continuous.

The shape of the projecting portion 61 may be such that the heights of the main portions are the same and there is no height difference, but the projecting portion 61 in this example has the peak portion 65 as described above. The peak portion 65 is formed at a position closer to the front wheel 12 in the vehicle front-rear direction of the protrusion portion 61, and the extension portion 66 extending rearward from the peak portion 65 in the protrusion portion 61 is formed so that the protruding height is low. Has been done.

The formation position of the peak portion 65 is a position not too close to the front wheel 12 and not too far from the front wheel 12, and the traveling wind flowing along the lower surface of the front floor undercover 19a travels behind the front wheel 12 having a slow speed. It is set to a position where it bends sideways under the influence of the wind.

Specifically, the position of the peak portion 65 in the vehicle front-rear direction is slightly rearward of the position corresponding to the upper end of the low resistance surface, which is the portion 59 outside the fixed recess 55 in the vehicle width direction (virtual in FIG. 1). Line circled P). The peak portion 65 may have an appropriate range in the front-rear direction of the vehicle.

Further, the lower surface 66a of the extension portion 66 behind the peak portion 65 in the projecting portion 61 is formed in a straight line. The rear end of the extension 66 is located at the rear end of the front floor undercover 19a.

As shown in FIG. 4, the front floor undercover 19a having such a configuration is fixed so that the lower surface 66a of the extension portion 66 is substantially horizontal when viewed from the side surface of the vehicle. Here, "substantially horizontal" means including horizontal.

That is, although it is exaggerated in FIG. 4, when the front floor undercover 19a is attached, the main body plate portion 52 is tilted downward toward the rear of the vehicle (α), and the extension portion 66 of the projecting portion 61 is tilted (α). The lower surface 66a of the vehicle is made horizontal when viewed from the side of the vehicle.

On the other hand, the rear floor undercover 19b is fixed so that the main body plate portion 52 is horizontal.

By such fixing of the front side floor undercover 19a and the rear side floor undercover 19b, most of the parts constituting the lower end position of the side view of the floor undercover 19 can be visually recognized horizontally.

Further, by tilting the rear portion of the main body plate portion 52 of the front floor undercover 19a downward, the position of the rear floor undercover 19b is positioned even slightly lower than when the front floor undercover 19a is horizontal. Will be done. That is, the position of the rear floor undercover 19b can be lowered while maintaining the continuity of the front floor undercover 19a and the rear floor undercover 19b connected to each other in the side view, and the large capacity of the fuel tank can be reduced. Contribute to the conversion.

In the lower body structure 11 having the tunnel undercover 18 and the floor undercover 19 as described above, the portion below the floor tunnel 14 behind the rear wall portion 32 of the tunnel undercover 18 is open.

In the lower body structure 11 configured as described above, the aerodynamic performance is improved as follows.

As shown by the arrows in FIG. 6, the traveling wind A flowing under the floor undercover 19 along the floor undercover 19 is faster than the speed of the traveling wind B behind the front wheels 12, so that the traveling wind behind the front wheels 12 Due to the influence of B, a part of A1 tries to blow out toward the outside in the vehicle width direction. At this time, the projecting portion 61 functions as a partition between the traveling wind A2 under the floor undercover 19 and the traveling wind B behind the front wheels 12, and a part of the traveling wind A1 under the floor undercover 19 It suppresses the outflow to the side behind the front wheel 12. Therefore, it is possible to suppress the generation of vortices behind the front wheels 12 under the floor and improve the aerodynamic performance.

The peak portion 65 of the projecting portion 61 is located closer to the front wheel 12, and flows along the low resistance surface of the portion 59 outside the fixed recess 55 in the vehicle width direction and behind the front wheel 12 away from the front wheel 12. Effectively suppresses the flow of air that is about to flow out to the side.

Moreover, since the inclined portion 64 that inclines upward toward the front is formed at the front end portion of the protruding portion 61, the traveling wind that hits the front end of the front floor undercover 19a is smoothly flowed around the protruding portion 61. Therefore, air resistance can be suppressed, which is effective in improving aerodynamic performance.

Similarly, a vertical wall portion 63 for connecting the fixed surface portion 62 and the main body plate portion 52 is provided in front of the projecting portion 61 in the vehicle direction, but the height of the vertical wall portion 63 is suppressed and smoothly. Since it can be made continuous with the front end of the projecting portion 61, air resistance can be suppressed from this point as well.

That is, although the aerodynamic performance is improved by providing the projecting portion 61, the desired effect can be obtained by forming the projecting portion 61 by reducing the air resistance in the front end portion of the projecting portion 61 and its vicinity as much as possible. The aerodynamic performance is effectively improved so that it will not be diminished.

Further, the projecting portion 61 is located at the outer end of the main body plate portion 52 in the vehicle width direction, and the lower surface 66a of the extension portion 66 behind the peak portion 65 in the projecting portion 61 is linear. Since the front floor undercover 19a is fixed so that the lower surface 66a is horizontal when viewed from the side surface of the vehicle, there is an advantage that the appearance can be improved in addition to the improvement of aerodynamic performance. That is, since the lower surface 66a of the extension portion 66 forming the contour / outer shape of the lower end in the side view of the front floor undercover 19a is horizontal, it is more beautiful than the case where it is tilted.

Moreover, since the rear floor undercover 19b, which also forms the contour and outer shape of the lower end in the side view, is fixed horizontally, a beautiful straight silhouette can be obtained with continuity with the front floor undercover 19a. Good aesthetics can be obtained as a whole.

In addition, as described above, the position of the rear floor undercover 19b can be lowered to increase the height of the area for accommodating the fuel tank, which contributes to increasing the size of the fuel tank.

A fixed surface 62 is formed in front of the projecting portion 61 in the vehicle front-rear direction, but since the projecting portion 61 is formed behind the vertical wall portion 63 rising from the fixed surface portion 62, this portion is also formed. A beautiful appearance can be obtained, which contributes to improving the appearance.

In addition, a rear wall portion 32 is formed at the rear end portion 18a of the tunnel undercover 18 provided so as to be sandwiched between the front end portions of the left and right floor undercovers 19. This also contributes to the improvement of the aerodynamic performance described above.

That is, when the vehicle is traveling, the air in the engine room flows in the floor tunnel 14 toward the rear of the vehicle along the floor tunnel 14. Since the inclined portion 14a is provided at the front end portion of the floor tunnel 14 as described above, the air flow is directed diagonally downward.

The air flow subsequently flows backward along the tunnel undercover 18 that blocks the lower part of the floor tunnel 14, but since the running wind flowing under the tunnel undercover 18 is faster, the tunnel undercover A phenomenon may occur in which air is blown downward at the rear end portion 18a of 18. When the air in the floor tunnel 14 blows downward, a vortex is generated there and not only the aerodynamic performance is deteriorated, but also the turbulence of the air flow at the rear end 18a of the tunnel undercover 18 is caused to the outer part in the vehicle width direction. May also affect.

However, since the rear wall portion 32 is formed at the rear end portion 18a of the tunnel undercover 18 as described above, the direction of the air flow is controlled to suppress the attempt to blow out downward. As a result, a smooth air flow can be realized as shown by arrows C in FIGS. 2 and 3.

In this way, the tunnel undercover 18 can also suppress the air flow that can deteriorate the aerodynamic performance, and can improve the aerodynamics more effectively.

The above configuration is a form for carrying out the present invention, and the present invention is not limited to the above-mentioned configuration, and other configurations can be adopted.

For example, the projecting portion 61 may be formed over the entire longitudinal direction of the floor undercover 19.

Further, the undercover of the present invention does not have to be a pair of left and right floor undercovers 19.

11 ... Lower body structure 12 ... Front wheels 19 ... Floor undercover 19a ... Front floor undercover 51 ... Fixed edge 52 ... Main body plate 61 ... Protruding part 62 ... Fixed surface part 63 ... Vertical wall part 64 ... Inclined part 65 ... Peak Part 66 ... Extension 66a ... Bottom surface

Claims (4)

A fixed edge portion that includes an undercover that extends in the front-rear direction from the position of the front wheel in the front-rear direction of the vehicle and forms a part of the lower surface of the vehicle body, and the undercover is fixed to the vehicle body side at an end portion on the outer side in the vehicle width direction. It is a lower body structure of a vehicle having a flat plate-shaped main body plate portion located inside the fixed edge portion in the vehicle width direction and below the fixed edge portion.
A projecting portion extending in the front-rear direction of the vehicle and projecting downward is formed on the outer edge portion of the main body plate portion in the vehicle width direction.
The projecting portion has a peak portion having the highest protruding height protruding downward from the lower surface of the main body plate portion at a position closer to the front wheel, and the protruding height is lower toward the rear from the peak portion. The lower body structure of the vehicle formed so as to be. The lower surface of the extension portion extending rearward from the peak portion in the projecting portion is formed in a straight line.
The lower body structure of a vehicle according to claim 1, wherein the undercover is fixed so that the lower surface of the extension portion is substantially horizontal when viewed from the side surface of the vehicle. The lower vehicle body structure of the vehicle according to claim 1 or 2, wherein an inclined portion that inclines upward toward the front is formed at the front end portion of the protruding portion. A fixed surface portion located above the main body plate portion and fixed to the vehicle body and a vertical wall portion connecting the fixed surface portion and the main body plate portion are provided at the front end portion of the undercover on the outer side in the vehicle width direction. Be,
The lower body structure of a vehicle according to any one of claims 1 to 3, wherein the projecting portion is formed behind the vertical wall portion.

Images