JP2803473B2 - Car underfloor structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underfloor structure capable of improving brake cooling performance of an automobile.

[0002]

2. Description of the Related Art In an underfloor structure of an automobile,
For example, as shown in Japanese Utility Model Laid-Open Publication No. 3-120280, an undercover disposed at a front portion of a vehicle with a lower portion of an engine room closed is provided, and a traveling wind is directed toward a front brake at an inner central portion of traveling wheels. Is known in which a guide portion for converging is provided.

[0003]

Since the traveling wind from the front of the traveling wheels is blocked by the traveling wheels, it is hardly introduced into the central portion inside the traveling wheels, and the traveling wind is converged by the guide portion of the undercover. Even if part of the wind is introduced inside the running wheel, the underwind is lower than the center of the running wheel, so the running wind will be introduced into the lower area inside the running wheel. , Not enough brake cooling effect can be expected.

Accordingly, the present invention is to provide an underfloor structure of an automobile in which a sufficient cooling air can be introduced into a central portion on the inner side of a traveling wheel and a brake cooling effect can be further enhanced.

[0005]

According to a first aspect of the present invention, there is provided a structure in which an undercover having a flat area at least in front of the traveling wheel is provided below a front portion of the vehicle. An air introduction section is provided on a flat portion in front of the vehicle, in a front extension area between the traveling wheel and the vehicle body-side attachment point of the suspension arm, and a portion where the underfloor flow of air from the front of the vehicle is reattached, The air introduction portion includes an inclined wall which is concavely formed upward from the lower surface of the under cover and is inclined toward the rear of the vehicle, and both side walls which extend from the inclined wall toward the rear of the vehicle and extend toward the rear of the vehicle so as to expand in the vehicle width direction. On the other hand, while having a duct structure, behind the air introduction portion, in the range of the inclination angle of the inclined wall, and in a region surrounded by an extension of both side walls, the rear end is inclined backward from the inside end to the outside end. , Air guide plate for directing the inner central portion of the running wheel upon receiving an air flow flowing out of the air introducing portion are disposed a.

According to a second aspect of the present invention, a wedge-shaped guide is provided on the upper surface of the under cover immediately after the duct opening of the air introduction portion, and the inclination angle of the guide surface of the guide is set to the inclination angle of the inclined wall of the air introduction portion. It is set to be almost the same as the angle.

According to a third aspect of the present invention, a rectifier having a plurality of partition walls in the vehicle width direction is provided on the upper surface of the under cover so as to be continuous with the duct opening of the air introducing portion.

According to a fourth aspect of the present invention, a notch is formed in a portion of the under cover corresponding to the wheel house for accommodating the traveling wheel, and an extension of the notch extends into the fork of the suspension arm. A part is formed, and a baffle plate is integrally formed with the extended part. According to the fifth aspect, the air guide plate is integrally provided on the front arm portion of the forked suspension arm.

[0009]

According to the first aspect, when the vehicle is running, the under-floor flow of the air that hits the front end of the vehicle and separates at the lower edge of the front end and goes under the undercover is generated at the reattached portion of the undercover. At the top of the undercover, it is trapped by the introduction section, flows out laminarly backward with the angle between the inclined wall and the side walls widening, and is deflected by hitting the baffle plate behind the air introduction section and inside the traveling wheel. Introduced in the center.

According to the second aspect, the airflow flowing out of the duct opening of the air inlet is deflected upward by the guide as a whole, so that the airflow is directed to the inner central portion of the traveling wheel having a higher ground height than the undercover. Is further improved.

According to the third aspect, since the airflow flowing out of the duct opening of the air introduction portion in a laminar flow state is rectified by the rectifier, the airflow is prevented from being diffused backward and can be intensively introduced into the baffle plate. Therefore, the effect of guiding air to the inner central portion of the traveling wheel can be further improved. According to the fourth aspect, since the air guide plate is formed integrally with the under cover, the number of parts is not increased, which is advantageous in cost.

According to the fifth aspect, since the air guide plate is provided on the front arm portion of the bifurcated suspension arm, it is effective when the layout of the air guide plate is difficult, and it is possible to reduce the number of running wheels as much as possible. It can be arranged close to the inner central part.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 16 and 17 show the internal structure of the running wheel 1 at the front of the vehicle, 2 is a hub that supports the running wheel 1, 3 is a brake rotor, 4 is a tire, 5 is a front strut, and 6 is a front strut. A suspension arm, 7 is a lower ball joint of the suspension arm 6, 8 is an axle housing, and 9 is a baffle plate holding the brake rotor 3.

The brake cooling is mainly due to the ventilation effect of the cooling air passing through the passage 3a in the brake rotor 3, and this cooling air is introduced from the annular opening area 9A at the center of the baffle plate 9 shown in FIG. The air
It is performed by flowing in the circumferential direction through the passage 3a in the brake rotor 3 as shown by the arrow f. Therefore, in order to increase the cooling effect of the brake, the area 9
A, that is, it is important to positively introduce cooling air from the outside to the center of the inside of the running wheel 1.

1 to 3 show an underfloor structure around the traveling wheel 1. Reference numeral 20 denotes an undercover which is disposed so as to close a lower side of an engine room E / R. In this embodiment, the undercover 20 is provided. It is formed entirely flat, and cutouts 21 are formed at portions corresponding to the front wheel house 10 on both sides thereof.

Considering the underfloor flow of air flowing along the underside of the undercover 20 from the front of the vehicle when the vehicle is running, as shown in FIG.
In the area C in front, the flow velocity is reduced due to the effect of the air flow being interrupted by the traveling wheels 1, and in the area B slightly shifted from the C area to the center of the vehicle, the influence of the traveling wheels 1 is reduced. Is relatively fast, and the flow velocity is the fastest in the region A at the center of the vehicle. This region A has a large effect on the aerodynamic characteristics of the vehicle, that is, the drag and lift.

Therefore, in front of the traveling wheel 1 of the undercover 20, there is little effect on the aerodynamic characteristics of the vehicle, and the region indicated by B in which the flow velocity is relatively high, specifically, the traveling wheel 1 and the suspension arm 6 vehicle body side mounting point 6a
An air introduction section 22 is provided on the front extension of the area D sandwiched between the front cover and the area where the underfloor air flow from the front of the vehicle is reattached to the undersurface of the undercover 20.

The air inlet 22 is provided with the under cover 20.
A duct structure comprising an inclined wall 23 that is recessed upward from the lower surface of the vehicle and is inclined toward the rear of the vehicle, and both side walls 24 that are connected to the inclined wall 23 and extend toward the rear of the vehicle and expand in the vehicle width direction. When the vehicle travels, it hits the front end of the vehicle and circulates downward, and re-adheres to the lower surface of the undercover 20 and flows the air of the underfloor flow into the lower duct opening 22.
a, and flows out rearward from the duct opening 22b on the rear side of the upper surface of the undercover 20 with the angle of formation of the inclined wall 23 and the side walls 24 being widened.

Here, considering the flow of air at the front end of the vehicle when the vehicle is running, as shown in FIG.
Traveling wind hits the front end portion, and flow to the top of the vehicle indicated by the arrow F _1, shunted to flow to the bottom of the vehicle indicated by the arrow F _2.

The flow F ₂ flowing downward from the vehicle once separates from the vehicle body surface at the corner UC of the lower edge of the front end of the vehicle, that is, at the front end of the under cover 20, and the streamline F ₂ is caused to flow by the main flow. the lower surface substantially parallel to bent, adhered abuts against the lower surface of the under cover 20 again, the flow in the vicinity of the front end portion of the under cover 20 to form a region F _2a closed flow vortices and backflow occurs.

The uniquely determined by the distance L is a function of the Reynolds number of the separation point at the corner portion U · C of the stream line F ₂ to the under cover 20 the lower surface of the reattachment point F _2b, is more than 380 Reynolds number in since L is a constant value, if the Reynolds number at the time of traveling as a vehicle is the fifth power of 10, the distance L from the separation point of the stream line F ₂ to reattachment point F _2b regardless of the vehicle speed substantially By setting the lower duct opening 22a at the lower side of the air introduction section 22 at the reattachment point _F2b , the air introduction section 22 efficiently captures the underfloor flow below the undercover 20 at the reattachment point F2b. It can be introduced to the upper surface side of the undercover 20.

The reattachment point F _2b of the streamline F ₂ is also affected by the shape of the corners U and C at the lower edge of the front end of the vehicle. 6, by forming a concave portion 20a near the front end of the undercover 20, the reattachment point _F2b can be moved to the front end side of the undercover 20. By adjusting the reattachment point F _2b in consideration of the above structure, it can be set at an arbitrary position in the front extension region D without being restricted by space.

On the other hand, behind the air introduction part 22, the air flow flowing out of the duct opening 22b on the rear side of the upper surface of the under cover 20 of the air introduction part 22 receives the air flow and directs the air toward the inner central part of the traveling wheel 1. A baffle 25 is provided.

The underfloor flow of the undercover 20 is caught by the duct opening 22 a of the air inlet 22, flows into the air inlet 22 in a turbulent state, and moves vertically along the inclined surface of the inclined wall 23. As it spreads, it spreads in the vehicle width direction along the wall surfaces of both side walls 24 and flows out rearward from the duct opening 22b, so that the pressure of the air flowing out from the duct opening 22b decreases and becomes laminar.

Therefore, the air guide plate 25 is connected to the duct opening 22b.
By arranging in the flow of laminar air flowing out of the vehicle, cooling air can be efficiently introduced into the brake-related parts at the central portion inside the traveling wheel 1.

Specifically, in order to efficiently introduce cooling air into the inner central portion of the traveling wheel 1, the air guide plate 25
In a range E within the range of the inclination angle θ of the inclined wall 23 of the air introduction part 22 and the extension of the side walls 24, 24.
In addition, it is disposed so as to be inclined backward from the inner end to the outer end.

The inclination angle of the baffle plate 25 is desirably set as shown in FIG.
, A straight line passing through the center of the air introduction part 22 is represented by L ₂ ,
The center point P of the brake rotor 3 at the inner center of the running wheel 1
, And a straight line connecting the straight line L ₂ and the intersection Q of the baffle plate 25 is L ₃ , the angle β ₁ between the baffle plate 25 and the straight line L ₂ ,
If the angle β ₂ between the air guide plate 25 and the straight line L ₃ is set to be substantially the same angle, the air flow flowing out of the air introduction section 22 in a laminar flow state is received by the air guide plate 25 and travels. It can be deflected to the wheel 1 side and can be positively introduced as cooling air to the target inner central portion of the running wheel 1.

In this embodiment, the baffle plate 25 is formed with an extended portion 21a projecting into the fork of the suspension arm 6 substantially at the center of the edge of the cutout portion 21 of the undercover 20. Is bent at the above-mentioned angle at the front edge.

The air guide plate 25 may be formed continuously with one of the side walls 24 of the air introducing portion 22, as shown in FIG. 7, in order to reinforce and improve the air guide effect. Good.

[0031] According to the above embodiment structure, running wind sneaks to the vehicle lower side when the front end of the vehicle B · F when the vehicle running becomes the underfloor flow of the undercover 20 as shown by F ₂ in FIG. 3, At the reattachment point F _2b of the under cover 20, the air is trapped in the lower duct opening 22a of the air inlet 22.

The inclined wall 23 of the air introduction section 22
And spreads out in the vertical direction and the vehicle width direction along the surface and both side walls 24, flows out as laminar flow from the rear side of the duct opening 22 b on the upper surface side of the under cover 20, and flows through the air guide plate 25 behind the duct opening 22 b. , And is deflected toward the traveling wheel 1, and is introduced into the inner central portion of the traveling wheel 1.

Therefore, since the cooling air can be positively sent to the central portion of the brake rotor 3 at the inner central portion of the running wheel 1, the ventilation effect by the cooling air passing through the passage 3a in the brake rotor 3 can be enhanced. The cooling effect of the brake can be further enhanced.

FIG. 8 shows an experimental result showing a change in wind speed near the brake rotor 3 due to actual running of the vehicle.
The line a represents the case of a vehicle equipped with the under cover 20 provided with the air introduction part 22 and the air guide plate 25 shown in the above-described embodiment, and the line b represents the general overall structure without the air introduction part 22 and the air guide plate 25. A vehicle having a flat undercover is shown in the figure. As is clear from the results of the measurement of the wind speed around the brake rotor 3, the specifications that do not have these structures due to the setting of the air introduction part 22 and the baffle plate 25. Cooling air can be introduced into the inner central portion of the traveling wheel 1 at a wind speed about five times as large as that of the first embodiment.

The cooling performance of the brake will be described in more detail. Generally, the cooling performance of the brake is evaluated based on the amount of heat radiated from the brake rotor 3.

Since the change in the amount of heat radiation corresponds to the change in the average heat transfer coefficient of the brake rotor 3, it can be estimated from the change in the Nusselt number (Nu number). For simplicity, assuming that the brake rotor 3 is a flat plate that is uniformly perpendicular to the flow of the cooling air, the Nu number is represented by a Reynolds number of R.
Assuming that _e , Nu = 0.3Re ^{0 · 5} + 0.083R _e ^{0 · 67} (1) Here, since Re is a linear function of the brake cooling air velocity u, Nu is given by Nu = 0.3u ^{0 · 5} + 0.083u ^{0 · 67} ‥‥‥ (2), which can be expressed as a function of the brake cooling air velocity.

Therefore, from the above equation (2), when the brake wind speed u becomes five times as described above, Nu becomes approximately three times, and the heat radiation amount of the brake rotor 3 is proportional to this Nu number. The amount of heat radiation can be reduced by about 3
It will be doubled.

FIGS. 9 and 10 show a second embodiment of the present invention, in which a wedge-shaped guide 26 is provided on the upper surface of the under cover 20 immediately after the duct opening 22b of the air inlet 22. FIG.

The angle θ ₂ of the guide surface of the guide 26 is set to be substantially the same as the angle of inclination θ of the inclined wall 23 of the air inlet 22.

Therefore, according to this embodiment, the air inlet 2
The air flow flowing out of the second duct opening 22b is
6, the cooling air can be more effectively introduced into the central portion of the inside of the traveling wheel 1 having a higher ground height than the undercover 20.

The embodiment shown in FIG. 11 has the wind guide plate 25 integrally provided on the front arm of the bifurcated suspension arm 6, and is effective when the layout of the wind guide plate 25 is difficult.

In the embodiment shown in FIGS. 12 and 13, a rectifier 27 having a plurality of partition walls 27a in the vehicle width direction is provided on the upper surface of the under cover 20 so as to be continuous with the duct opening 22b of the air introducing portion 22. It is.

According to this embodiment, the air flow flows out of the duct opening 22b of the air introduction part 22 in a laminar flow state. However, the air flow is rectified by the rectifier 27 to suppress the diffusion to the rear. Since the air can be intensively introduced into the wind guide plate 25, the effect of guiding the air into the inner central portion of the traveling wheel 1 can be further improved. In particular, the guide 26 of the embodiment shown in FIGS. It is more effective if combined with the above structure.

In any of these embodiments, as described above, it is possible to improve the cooling performance of the brake rotor 3 by increasing the cooling air velocity into the inside central portion of the traveling wheel 1, but this cooling air velocity is As shown by the line a in FIG. 8, in a region where the vehicle speed is high, the increase in the wind speed becomes a saturated state.

This is mainly due to the front wheel house 1
This is because the pressure in 0 is increasing, and FIG.
It is effective to reduce the pressure rise in the front wheel house 10 by making the inside of the running wheel 1 in the front wheel house 10 communicate with the outside as shown in FIGS.

In this embodiment, openings 13 and 14 are provided in the upper part of the front fender 11 and the upper part of the inner protector 12 of the front wheel house 10, and the decorative louver 15 is provided in the opening 13 of the front fender 11.
Is provided to allow the inside portion of the traveling wheel 1 in the front wheel house 10 to communicate with the outside.

Therefore, according to this embodiment, even when the vehicle is running at a high speed, the pressure rise in the front wheel house 10 can be suppressed to a low level.
Due to the wind guiding effect of 2 and the wind guide plate 25, the cooling wind speed to the inner central portion of the running wheel 1 can be increased, and the brake cooling effect can be maintained high up to the high speed range of the vehicle.

In each of the above-described embodiments, the structure for introducing the cooling air to the running wheels 1 at the front of the vehicle has been described. However, the structure can be applied to the structure for introducing the cooling air to the running wheels at the rear of the vehicle.

[0049]

As described above, according to the present invention, the air introduction portion provided on the under cover at the front of the vehicle and the air guide plate provided behind the air introduction portion act to guide the inner center of the traveling wheel. Since sufficient cooling air can be introduced into the section, there is an advantage that the cooling effect of the brake disposed in the central portion inside the traveling wheel can be further enhanced.

In particular, a wedge-shaped guide is provided on the upper surface of the undercover immediately after the duct opening of the air introduction section,
If the angle of inclination of the guide surface of the guide is set to be substantially the same as the angle of inclination of the inclined wall of the air introduction section, the airflow flowing out of the duct opening of the air introduction section can be entirely deflected upward by the guide. Therefore, the effect of introducing the cooling air to the inner central portion of the traveling wheel having a higher ground height than the undercover can be further improved.

Further, if a rectifier having a plurality of partition walls in the vehicle width direction is provided on the upper surface of the under cover and continuous with the duct opening of the air introducing portion, the air flow flowing out of the duct opening in a laminar flow state. Is rectified by the rectifier, so that the rearward diffusion can be suppressed and the air can be intensively introduced into the wind guide plate, so that the effect of guiding the wind to the inner central portion of the traveling wheel can be further improved.

If the air guide plate is formed integrally with the extended portion protruding from the cutout portion of the undercover, it is possible to avoid an increase in the number of parts and to obtain an advantage in cost.

Further, if the air guide plate is provided on the front arm portion of the bifurcated suspension arm, even if layout of the air guide plate on the undercover is difficult, the air guide plate is located as close as possible to the inner central portion of the traveling wheel. Can be arranged.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a half showing an embodiment of the present invention.

FIG. 2 is a side view of the under cover of the embodiment.

FIG. 3 is a schematic perspective explanatory view of the embodiment.

FIG. 4 is an explanatory plan view showing an arrangement relationship between an air introduction unit and a baffle plate of the embodiment.

FIG. 5 is an explanatory view of the under cover, which shows the under-floor flow of air below the under cover, as viewed from below.

FIG. 6 is a schematic side view illustrating the flow of air at the front of the vehicle.

FIG. 7 is a perspective view showing a different example of the under cover.

FIG. 8 is a graph showing a relationship between a vehicle speed and a wind speed of a brake rotor cooling wind.

FIG. 9 is a schematic perspective explanatory view showing a second embodiment of the present invention.

FIG. 10 is a side view of the under cover of the embodiment.

FIG. 11 is a schematic perspective explanatory view showing a third embodiment of the present invention.

FIG. 12 is a schematic perspective explanatory view showing a fourth embodiment of the present invention.

FIG. 13 is a side view of the under cover of the embodiment.

FIG. 14 is a perspective view of a vehicle provided with a fifth embodiment of the present invention.

FIG. 15 is a schematic sectional explanatory view taken along the line AA of FIG. 14;

FIG. 16 is a cross-sectional view showing a structure of a traveling wheel at a front portion of a vehicle to which the present invention is applied.

FIG. 17 is an enlarged view of a main part of FIG. 16;

[Explanation of symbols]

1 ... running wheel 6 ... suspension arm 20 ... undercover 22 ... air introducing portion 23 ... inclined wall 24 ... side walls 25 ... air guide plate 26 ... Guide 27 ... Rectifier 27a ... partition wall F ₂ ... underfloor flow F _2b ... reattachment point

Continuation of the front page (56) References Japanese Utility Model Sho 63-145715 (JP, U) Japanese Utility Model Sho 59-38176 (JP, U) Japanese Utility Model Sho 58-115472 (JP, U) Japanese Utility Model Sho 58-164976 (JP) , U) Actually open 55-163448 (JP, U) Actually open 2-130887 (JP, U) Actually open 1-73471 (JP, U) Actually open 3-120280 (JP, U) (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 25/20

Claims (5)

(57) [Claims] 1. A structure in which an undercover having a flat area at least in front of a traveling wheel is provided below a front portion of a vehicle, wherein the running wheel is provided on a flat portion of the undercover ahead of the traveling wheel. An air introduction section is provided in a front extension area between the suspension arm and the vehicle body side attachment point, and at a portion where the underfloor flow of air from the front of the vehicle is reattached, and the air introduction section is directed upward from the under cover lower surface. A duct structure consisting of a recessed inclined wall inclined toward the rear of the vehicle and both side walls extending from the inclined wall toward the rear of the vehicle and diverging in the vehicle width direction, while having a duct structure, Receiving an air flow that inclines rearward from the inside end to the outside end in a range of the inclination angle of the inclined wall and is surrounded by the extension of the both side walls, and flows out from the air introduction part. An underfloor structure for an automobile, wherein a wind guide plate is provided to be directed toward the center of the inside of the running wheel. 2. A wedge-shaped guide is provided on the upper surface of the under cover immediately after the duct opening of the air introduction portion, and the inclination angle of the guide surface of the guide is set to be substantially the same as the inclination angle of the inclined wall of the air introduction portion. The underfloor structure of an automobile according to claim 1, wherein 3. A rectifier having a plurality of partition walls in a vehicle width direction is provided on an upper surface of the under cover so as to be continuous with a duct opening of an air introduction part.
The underfloor structure of the vehicle as described. 4. The undercover has a notch at a portion corresponding to a wheel house for accommodating a traveling wheel, and an extended portion protruding into a fork of a suspension arm is formed at an edge of the notch. 4. An underfloor structure for an automobile according to claim 1, wherein said extension portion is integrally formed with a baffle plate. 5. The underfloor structure of an automobile according to claim 1, wherein the air guide plate is provided integrally on a front arm portion of the bifurcated suspension arm.