JP5560863B2 - Underfloor structure of vehicle - Google Patents

Description

  The present invention relates to a vehicle underfloor structure in which a vehicle underfloor is covered with an undercover, and drainage means is provided on the undercover.

  Conventionally, as an underfloor structure in which a drainage means is provided in an under cover that covers the underfloor of a vehicle, a recess having a concave bottom surface is provided, and a portion of the drain is applied to a portion of the outer peripheral portion located on the front side of the vehicle body. What provided the hole is known (for example, refer patent document 1).

  In this conventional underfloor structure, the drain hole is an oblong hole elongated in the vehicle front-rear direction, and a recess is formed in which a part of the oblong hole is applied, so that the lower surface of the under cover can be provided during traveling. The flowing air is less likely to flow above the undercover. That is, it aims at providing the undercover provided with the drain hole from which water does not easily enter from the outside.

JP 2001-18852 A

  However, in the conventional underfloor structure, the drain hole is an oblong hole elongated in the vehicle front-rear direction (FIG. 4 of Patent Document 1). For this reason, even if the increase in air resistance can be suppressed, when a large amount of water or muddy water enters the under cover, the water drained from the outside due to the narrow opening area of the drain hole and low drainage capacity. There was a problem that water and muddy water were accumulated in the under cover.

  Furthermore, in the conventional underfloor structure, most of the opening portions of the drain holes are exposed on the cover surface formed along the flow of the running air in the under cover (FIG. 5 of Patent Document 1). For this reason, if the drainage capacity is increased by increasing the opening area of the drain hole, the exposed opening area to the cover surface also increases, so that the traveling wind is taken in from the drain hole and the traveling wind flows around the drain hole. It will cause turbulence and increase air resistance.

  The present invention has been made paying attention to the above-mentioned problem, and can improve the aerodynamic performance of the vehicle as a whole by suppressing the increase in air resistance while securing the drainage capacity from the under cover during traveling. The purpose is to provide an underfloor structure.

To achieve the above object, the present invention covers the floor of the vehicle under a cover, in the underfloor structure of a vehicle provided with drainage means to the undercover, a vehicle forward position than the front tires, the vehicle of the undercover A curved protrusion is disposed at a substantially central part in the vehicle width direction of the front part of the vehicle across the center line, and the drainage means is disposed at a position behind the curved protrusion from the curved protrusion so as to be separated from the curved protrusion .
The drainage means is provided with a front inclined wall and a rear inclined wall.
The front inclined wall is inclined upward from the front side wall end portion extending in the vehicle width direction of the under cover toward the rear of the vehicle, and the drain port is opened through at least a part of the wall.
The rear inclined wall is inclined downward from the bent wall portion connected to the front inclined wall toward the rear side wall end portion extending in the vehicle width direction of the under cover, and the traveling airflow is adjusted on the wall surface. It has a wind rectifying surface.
Then, the hollow shape in the vehicle front-rear direction from the under cover is such that the first inner angle by the front inclined wall is larger than the second inner angle by the rear inclined wall, and the two wall lengths are made different.

In the present invention, considering that the two functions of the drainage function and the rectifying function are compatible, the wall constituting the depression is divided into two, a front inclined wall and a rear inclined wall by bending, and the front inclined wall is drained. A drainage means having a mouth and a running wind rectifying surface on the rear inclined wall was adopted.
For this reason, during traveling, when traveling wind flows into the recess from the front side wall end, the traveling wind received by the traveling wind rectifying surface of the rear inclined wall is arranged so as to draw a smooth streamline, to the rear side wall end And let it flow. At this time, the hollow shape in the vehicle front-rear direction from the undercover is such that the first inner angle by the front inclined wall is larger than the second inner angle by the rear inclined wall, and the two wall surface lengths are made different. Therefore, the traveling wind that has flowed into the recess from the front side wall end reaches the traveling wind rectifying surface while drawing a streamline that gradually moves away from the drain port.
In this way, the drainage opening opens to the front inclined wall where the intake of traveling wind is suppressed even if the opening area is enlarged, and shows the drainage action to quickly drain the water in the cover, so The drainage capacity is secured. On the other hand, the traveling wind rectifying surface has a rear inclined wall that receives the flow of traveling wind flowing into the depression as it is, and exhibits a rectifying action that adjusts the streamline of the traveling wind flowing through the depression, so that it can smoothly flow along the under cover. Running wind flows through the air, and the increase in air resistance is suppressed.
Accordingly, it is possible to achieve an improvement in the aerodynamic performance of the vehicle as a whole by suppressing an increase in air resistance while ensuring the drainage capacity from the undercover during traveling.

It is the perspective view seen from the slanting lower side of the vehicle which shows the whole under floor of the electric vehicle (an example of a vehicle) to which the under-floor structure of Example 1 is applied. FIG. 3 is a perspective view of the rear under cover in the underfloor structure of the first embodiment when viewed from the diagonally upper front side of the vehicle. FIG. 2 is a perspective view of the rear undercover in the underfloor structure of the first embodiment as viewed from the diagonally upper rear side of the vehicle. It is an expansion perspective view which shows the drainage means provided in the rear undercover in the underfloor structure of Example 1. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4 showing drainage means provided in a rear undercover in the underfloor structure of the first embodiment. FIG. 5 is a cross-sectional view taken along the line B-B in FIG. 4, showing drainage means provided on the rear undercover in the underfloor structure of the first embodiment. It is a pie chart figure showing resistance generation source classification of air resistance in a general passenger car (engine car). FIG. 3 is a traveling wind flow diagram showing a flow of traveling wind flowing under the floor and around the entire tire in the electric vehicle of the first embodiment. It is a driving | running | working wind stream diagram which shows the flow of the driving | running | working wind which flows around the drainage means when the hollow of the drainage means is seen from the side in the vertical cross section in the electric vehicle to which the underfloor structure of Example 1 is applied. It is a driving | running | working wind stream diagram which shows the flow of the driving | running | working wind which flows around the drainage means when the hollow of a drainage means is seen from right under in the electric vehicle to which the underfloor structure of Example 1 is applied.

  Hereinafter, the best mode for realizing the under-floor structure of a vehicle of the present invention will be described based on Example 1 shown in the drawings.

First, the configuration will be described.
FIG. 1 is a perspective view showing the entire under floor of an electric vehicle (an example of a vehicle) to which the under-floor structure of the first embodiment is applied. Hereinafter, the entire underfloor structure will be described with reference to FIG.

  As shown in FIG. 1, the overall underfloor structure of the electric vehicle EV of the first embodiment is a pair of left and right front tires 1L and 1R, a pair of left and right rear tires 2L and 2R, a front under cover 3, and a motor room rear under cover. 4, a first battery under cover 5, a second battery under cover 6, a rear under cover 7 (under cover), a pair of left and right front deflectors 8L and 8R, and a pair of left and right rear deflectors 9L and 9R. I have.

  The pair of left and right front tires 1L and 1R are steering wheels and drive wheels, and are elastically supported by the vehicle body via a front suspension link (not shown).

  The pair of left and right rear tires 2L, 2R are elastically supported by the vehicle body via a rear suspension (not shown) such as a trailing suspension.

  The front under cover 3 is a member that covers a front underfloor region from the flange portion 11a of the front bumper facer 11 to a front suspension member (not shown). The cover surface of the front under cover 3 is formed into a smooth folded surface by an inclined portion 3a inclined downward toward the rear of the vehicle and a horizontal portion 3b continuous to the inclined portion 3a. The inclined portion 3a is formed with a curved protrusion 31 having a major axis in the vehicle width direction, and the horizontal portion 3b has four protrusions 32 extending in the vehicle front-rear direction, two drain holes 33 and 34, Is formed. Further, the front under cover 3 has inclined side surfaces 35 and 35 whose width is gradually reduced toward the rear of the vehicle.

  The motor room rear under cover 4 is a member that covers a central front lower floor region from a front suspension member (not shown) to the motor room rear. The cover surface of the motor room rear under cover 4 is formed in a horizontal plane at the same position as the horizontal portion 3 b of the front under cover 3. The motor room rear under cover 4 includes four protrusions 41 extending in the vehicle front-rear direction, two drain holes 42 and 43 having a small opening area on the front side of the vehicle, and one having a large opening area on the vehicle rear side. A drain port 44 is formed.

  The first battery under cover 5 and the second battery under cover 6 are members that cover the central rear lower floor region from the rear of the motor room to the rear end of the battery unit (not shown) by connecting them together. The cover surfaces of the battery undercovers 5 and 6 are formed in a horizontal plane at the same position as the cover surface of the motor room rear undercover 4. The two battery undercovers 5 and 6 are formed with four protrusions 51 and 61 extending in the vehicle front-rear direction. The motor room rear under cover 4 and the battery under covers 5 and 6 are connected to each other to form a center under cover as a whole.

  The rear under cover 7 is a member that covers a rear lower floor region from a rear suspension member (not shown) to a flange portion 13 a of the rear bumper fascia 13. The cover surface 7a of the rear under cover 7 has a diffuser structure formed on a curved inclined surface that gently inclines upward from the position of the same horizontal plane as the second battery under cover 6 toward the rear of the vehicle. The rear under cover 7 is arranged between the four straightening ridges 71 extending in the longitudinal direction of the vehicle and gradually increasing in height toward the rear of the vehicle, and between the straightening ridges 71 and at the entrance position of the diffuser structure. The three drain holes 72, 73, 74 thus formed are formed.

  The pair of left and right front deflectors 8L and 8R are provided so as to protrude downward from the front positions of the pair of left and right front tires 1L and 1R, and adjust the flow of traveling wind that flows around the front tires 1L and 1R during traveling.

  The pair of left and right rear deflectors 9L and 9R are provided so as to protrude downward from the front positions of the pair of left and right rear tires 2L and 2R, and adjust the flow of traveling wind flowing around the rear tires 2L and 2R during traveling.

  2 and 3 are perspective views showing the rear under cover 7 in the underfloor structure of the first embodiment. Hereinafter, the configuration of the rear under cover 7 will be described with reference to FIGS. 2 and 3.

  As shown in FIGS. 2 and 3, the rear under cover 7 of Example 1 has a tray shape that covers the rear lower floor area and collects water, muddy water, and the like, and is integrally formed by press molding using a synthetic resin as a raw material. Manufactured. The rear under cover 7 is formed with four straightening ridges 71, 71, 71, 71 extending in the vehicle front-rear direction and gradually increasing in height toward the rear of the vehicle. And there are provided drainage means D, D, D in which three drain holes 72, 73, 74 arranged between the straightening ridges 71, 71, 71, 71 and arranged at the inlet position of the diffuser structure are opened. It is done.

  The rear under cover 7 is formed with a rising portion 7b around the cover excluding the rear end portion overhanging the flange portion 13a of the rear bumper fascia 13. A flange portion 7c is formed on the entire circumference including the rising portion 7b, and a plurality of bolt holes 7d are opened in the flange portion 7c. And the rear under cover 7 is attached under the rear floor by inserting and tightening bolts not shown in the plurality of bolt holes 7d.

  4-6 is a figure which shows the drainage means D provided in the rear undercover 7 (an example of an undercover) in the underfloor structure of Example 1. FIG. It should be noted that the drain ports 33 and 34 formed in the front under cover 3, the drain ports 42, 43 and 44 formed in the motor room rear under cover 4, and the drain port 72 formed in the rear under cover 7. , 73, 74 are open to the drainage means D having the same configuration. Hereinafter, based on FIGS. 4 to 6, the drainage port 73 of the rear under cover 7 among the plurality of drainage ports is taken as a representative example, and the configuration of the drainage means D in which the drainage port 73 is opened will be described.

  As shown in FIGS. 4 to 6, the drainage means D according to the first embodiment includes a front inclined wall 21, a rear inclined wall 22, a left side wall 23, a right side wall 24, a water drain port 73, and traveling wind. And a rectifying surface 25. That is, a hollow space surrounded by the front inclined wall 21, the rear inclined wall 22, the left side wall 23, and the right side wall 24 is formed in the rear under cover 7. The front inclined wall 21 has a drain port 73, and the rear inclined wall 22 has a traveling wind rectifying surface 25.

  As shown in FIG. 5, the front inclined wall 21 is inclined upward from the front side wall end portion 26 extending in the vehicle width direction of the rear under cover 7 toward the rear of the vehicle, and penetrates at least a part of the wall. The drain port 73 is opened. The drain port 73 is opened in a rectangular shape substantially conforming to the outer peripheral shape of the front inclined wall 21, and the opening front edge 73 a is set in the region of the front side wall end portion 26 where the front inclined wall 21 starts to be inclined upward. doing.

  As shown in FIG. 5, the rear inclined wall 22 is inclined downward from a bent wall portion 27 connected to the front inclined wall 21 toward a rear side wall end portion 28 extending in the vehicle width direction of the rear under cover 7. The wall has a running air rectifying surface 25 for adjusting the flow of the running wind. As the traveling wind rectifying surface 25, the wall surface of the rear inclined wall 22 is used as it is. The traveling wind rectifying surface 25 is smoothly connected to the cover surface 7a of the rear undercover 7 in the region of the flat surface 25a from the bent wall portion 27 toward the rear side wall end portion 28 and the rear side wall end portion 28. Arc surface 25b.

  As shown in FIG. 6, the left side wall 23 has a pair of triangles formed facing each other in the vehicle width direction by recessing a front side inclined wall 21 and a rear side inclined wall 22 bent from the rear under cover 7. Of the shape space, the left space is provided.

  As shown in FIG. 6, the right side wall 24 has a pair of triangles formed facing each other in the vehicle width direction by recessing a front side inclined wall 21 and a rear side inclined wall 22 bent from the rear under cover 7. It is provided so as to block the right side space in the shape space.

  Here, as shown in FIG. 4, the left side wall 23 and the right side wall 24 gradually decrease in width W due to the two wall surfaces 23 a and 24 a facing in the vehicle width direction from the front of the vehicle toward the rear of the vehicle. It is set to do.

A hollow shape in the vehicle front-rear direction from the rear undercover 7 by the front inclined wall 21 and the rear inclined wall 22 will be described.
A hollow shape in the vehicle front-rear direction from the rear under cover 7 is formed by the wall surface 21a of the front inclined wall 21, the wall surface of the rear inclined wall 22 (running wind rectifying surface 25), and the cover surface 7a of the rear under cover 7. As shown in FIG. 5, it is set as the triangular hollow shape which made two wall surface length L1, L2 differ. That is, the first interior angle θ1 formed by the wall surface 21a of the front inclined wall 21 with respect to the cover surface 7a of the rear under cover 7 is the running wind rectifying surface 25 of the rear inclined wall 22 with respect to the cover surface 7a of the rear under cover 7. Is set larger than the second interior angle θ2. Thereby, when the wall length of the front inclined wall 21 is L1, the wall length of the rear inclined wall 22 is L2, and the recess length connecting the front side wall end portion 26 and the rear side wall end portion 28 is L3, The length relationship of L1 <L2 <L3 is set. That is, the wall surface length L1 of the front inclined wall 21 that opens the drainage port 73 is shortened, and the wall surface length L2 of the rear inclined wall 22 serving as the traveling wind rectifying surface 25 is increased.

  Here, the first interior angle θ1 is set to an angle larger than the inflow angle of the traveling wind entering from the front side wall end portion 26 of the rear under cover 7. For example, when the design value of the inflow angle is 30 °, the first interior angle θ1 is an angle larger than 30 ° (for example, 45 ° to 90 °). Set to

  The second interior angle θ2 is set to an angle that suppresses the deflection of the streamline of the traveling wind that passes from the traveling wind rectifying surface 25 to the rear side wall end portion 28 of the rear undercover 7. The angle that suppresses the deflection of the streamline of the traveling wind refers to an angle that secures the flow of the traveling wind that suppresses the occurrence of separation, and is set to an angle of 5 ° to 15 °, for example.

Next, the operation will be described.
First, “about the air resistance of the vehicle” will be described. Subsequently, the actions in the underfloor structure of the electric vehicle EV of Example 1 are “the aerodynamic performance improving action by the underfloor and the whole tire”, “the drainage action by the drainage means and the running wind rectifying action”, “the drainage capacity securing action by the drainage means” ”And“ Suppressing the increase in running resistance by the drainage means ”.

[Vehicle air resistance]
The air resistance D (N) of the vehicle is
D = CD × 1/2 × ρ × u ² × A (1)
Where CD: Air resistance coefficient (Dimensionless)
ρ: Air density (kg / m ³ )
u: Relative speed between air and vehicle (m / sec)
A: Front projection area (m ² )
It is defined by the formula of
As is clear from the above equation (1), the air resistance D is proportional to the air resistance coefficient CD (abbreviation of Constant Drag), and the relative speed u between the air and the vehicle (= running wind speed, for example, when there is no wind) Is a value proportional to the square of the vehicle running speed).

To reduce this air resistance D,
(a) How far does the air resistance coefficient CD deviate from the target?
(b) Where is the cause of the deviation from the target?
(c) How close will it be to the goal if the cause is eliminated?
This is a series of processes. Of these, (a) and (c) can be known from the air resistance coefficient CD calculated by accurate computational fluidics, but in order to accurately identify (b), the speed calculated from computational fluidics Or pressure alone is difficult.

  Regarding the air resistance D, FIG. 7 shows a resistance generation source classification of air resistance in a general passenger car (engine car). As shown in FIG. 7, the largest resistance generation source is the vehicle outer shape. However, the second largest source of resistance is under the floor and tires, exceeding the air resistance caused by engine room ventilation. In other words, it cannot be asserted that the air resistance D depends only on the external styling of the vehicle, and consideration must be given to resistance generation sources such as the underfloor, tires, and engine room ventilation (motor room ventilation in the case of an electric vehicle). I understand that.

  On the other hand, aerodynamic performance improvement for reducing the air resistance D has been made mainly by paying attention to the external styling of the vehicle. However, for example, in the case of a vehicle that needs to ensure the comfortability of the rear seat, even if the aerodynamic performance is improved by styling the outer shape of the vehicle, there is a limit due to the design restriction of securing the rear seat living space. In other words, when the desired aerodynamic performance is set at a high level in order to extend the cruising distance, the improvement to reach the desired aerodynamic performance cannot be desired only by improving the external styling of the vehicle.

  In particular, in the case of an electric vehicle equipped with a battery in a limited space under the floor, it can be said that how long the cruising distance is extended with a battery capacity determined by full charging. In this electric vehicle, when the aerodynamic performance improvement by vehicle styling is at the limit, reducing the air resistance by the underfloor and the whole tire as much as possible means that the reduction of the air resistance of the electric vehicle as a whole extends the cruising distance as it is. This is a very important technical issue.

  In order to effectively reduce the air resistance of the underfloor and the entire tire, it is effective to provide an undercover for lowering the air resistance coefficient CD under the floor. The undercover is provided with drainage means so as to have drainage properties, but it is necessary to suppress an increase in air resistance due to the drainage means while ensuring the drainage capacity of the drainage means.

[Aerodynamic performance improvement effect under the floor and the entire tire]
As described above, in an electric vehicle, reducing the air resistance caused by the underfloor and the entire tire as much as possible is important in extending the cruising distance. Hereinafter, the aerodynamic performance improvement effect by the whole under the floor and the tire in the electric vehicle EV of Example 1 reflecting this will be described.

  As shown in FIG. 8, the electric vehicle EV covers almost the entire area under the floor except for tires and the like with undercovers 3, 4, 5, 6, and 7. As a result, a continuous smooth surface without unevenness is ensured from the front end of the vehicle to the rear end of the vehicle, and the main stream line bundle FMAIN passing through the center under the floor centering on the vehicle center line CL is formed by the traveling wind flowing from the front of the vehicle. The For this reason, the traveling wind flowing in from the front of the vehicle passes through the undercovers 3, 4, 5, 6, and 7 and smoothly exits to the rear of the vehicle. In particular, since the rear under cover 7 that covers the lower part of the rear floor has a diffuser structure, the action of promoting the escape of traveling wind to the rear of the vehicle is also added. Thus, the airflow D in the center area under the floor is lowered by the traveling wind flowing in an orderly and smoothly manner in the center area under the floor from the vehicle front end to the vehicle rear end.

  As shown in FIG. 8, the electric vehicle EV is provided with a pair of left and right front deflectors 8L and 8R in front of the pair of left and right front tires 1L and 1R. Thereby, during traveling, the flow of the traveling wind flowing around the front tires 1L and 1R is adjusted so as to suppress the flow of traveling wind around the front tires 1L and 1R. As a result, the air resistance D in the peripheral region of the front tires 1L and 1R is reduced by suppressing the flow of the traveling wind into the peripheral region of the front tires 1L and 1R, which is a main cause for increasing the air resistance.

  As shown in FIG. 8, the electric vehicle EV is provided with a pair of left and right rear deflectors 9L and 9R in front of the pair of left and right rear tires 2L and 2R. As a result, the flow of the traveling wind is adjusted so as to detour around the rear tires 2L, 2R during traveling. As a result, the air resistance D in the peripheral region of the rear tires 2L and 2R is reduced by the traveling wind that bypasses around the rear tires 2L and 2R.

  As shown in FIG. 8, the electric vehicle EV is provided with a curved protrusion 31 for controlling the flow velocity of the traveling wind on the front under cover 3. This suppresses the spread of the traveling wind that flows from the front of the vehicle during traveling, and forms the mainstream line bundle FMAIN that passes through the center part under the front floor centered on the vehicle center line CL. As a result, the traveling wind flowing from the front end of the vehicle is collected in the central region under the front floor, and the air resistance D in the central region under the front floor is reduced.

  As described above, the electric vehicle EV of Example 1 employs an underfloor structure aimed at improving the aerodynamic performance of these underfloor and tires as a whole. For this reason, the air resistance D under the floor of the electric vehicle EV and the entire tire is reduced, and the overall aerodynamic performance that extends the cruising distance of the electric vehicle EV can be achieved.

[Draining action and running wind rectification action by drainage means]
As mentioned above, in an electric vehicle, in order to effectively reduce the air resistance of the underfloor and the entire tire, it is necessary to suppress the increase in air resistance while ensuring the drainage capacity by the drainage means set in the under cover It is. Hereinafter, the drainage action and running wind rectification action by the drainage means D provided on the rear under cover 7 of the first embodiment reflecting this will be described.

  In Example 1, as described above, a configuration was adopted in which almost the entire area under the floor except for the tires and the like was covered with the undercovers 3, 4, 5, 6, and 7. This is because the undercover has an effect of lowering the air resistance coefficient CD under the floor of the vehicle and improving the aerodynamic performance of the entire vehicle. However, since the shape of the undercover is a tray shape that collects water, muddy water, and the like that has entered from the outside, a draining means is required, and it is generally performed with a drain hole exposed on the cover surface. If the opening area of the drain hole is reduced, the increase in air resistance can be suppressed, but the drainage capacity is reduced by limiting the drainage flow rate per unit time. On the other hand, when the opening area of the drain hole is increased, the drainage capacity is increased, but the air resistance is increased by the running wind being taken into the drain hole. Thus, ensuring the drainage capacity and suppressing the increase in air resistance are in a trade-off relationship that is difficult to achieve at the same time.

  On the other hand, in Example 1, considering that the two functions of the drainage function and the rectifying function are compatible, the wall constituting the depression is divided into two, a front inclined wall 21 and a rear inclined wall 22 by bending. The drainage means D having the drainage port 73 in the front inclined wall 21 and the traveling wind rectifying surface 25 in the rear inclined wall 22 is employed.

  For this reason, during traveling, the traveling wind flowing along the cover surface 7 a of the rear under cover 7 flows into the recess from the front side wall end portion 26 extending in the vehicle width direction of the rear under cover 7. Then, when the traveling wind flows into the depression, as shown in FIG. 9, the traveling wind rectifying surface 25 of the rear inclined wall 22 receives and deflects the received traveling wind flow by a gradual change in angle, thereby rectifying the traveling wind. It is arranged to draw a smooth streamline along the surface 25. Then, the rear side wall end portion 28 extending in the vehicle width direction of the rear under cover 7 passes smoothly without being peeled off, and again flows out to the cover surface 7 a of the rear under cover 7.

  At this time, the vehicle interior longitudinal direction recess shape of the rear under cover 7 is such that the first inner angle θ1 formed by the wall surface 21a of the front inclined wall 21 with respect to the cover surface 7a is the wall surface 22a of the rear inclined wall 22 with respect to the cover surface 7a. Is defined as a triangular depression shape having an angle larger than the second inner angle θ2 formed by the two and having two wall surfaces of different lengths. Therefore, the traveling wind that has flowed into the depression from the front side wall end portion 26 reaches the traveling wind rectifying surface 25 while drawing a streamline that gradually moves away from the drain port 73, as shown in FIG.

  As described above, since the drain port 73 is opened in the front inclined wall 21 that can suppress the intake of the traveling wind even if the opening area is enlarged, as shown by an arrow E in FIG. Even if there is a large amount of water or muddy water that has entered from the water, it shows the drainage action of draining it quickly. That is, the drainage capacity from the rear under cover 7 is ensured.

  On the other hand, the travel wind rectifying surface 25 is provided on the rear inclined wall 22 that receives the flow of the travel wind flowing into the depression as it is, so that the flow velocity of the travel wind flowing through the depression is high as shown by the streamline F in FIG. Also shows a rectifying action to arrange a streamline without causing separation or turbulence. That is, the traveling wind flows smoothly along the rear under cover 7 and the increase in air resistance is suppressed.

  As described above, the drainage means D of the first embodiment has two walls of the front inclined wall 21 and the rear inclined wall 22 formed by bending to form a recess, and the drainage port 73 is formed in the front inclined wall 21. And a running wind rectifying surface 25 is provided on the rear inclined wall 22. The shape of the recess is such that the first inner angle θ1 due to the front inclined wall 21 is larger than the second inner angle θ2 due to the rear inclined wall 22, and the two wall lengths are made different. For this reason, the improvement of aerodynamic performance as the whole vehicle can be achieved as a result of suppressing an increase in air resistance while ensuring the drainage capacity from the rear undercover 7 during traveling.

[Ensuring drainage capacity by drainage means]
The drainage means needs to secure the drainage capacity required for rainy road traveling or the like in order to protect the parts covered by the undercover from the influence of water. Hereinafter, the drainage capacity ensuring action by the drainage means D provided on the rear undercover 7 of the first embodiment reflecting this will be described.

  As described above, generally, when the opening area of the drain hole is reduced, the increase in air resistance is suppressed, but the drainage capacity is reduced by limiting the drainage flow rate per unit time by the small opening area. Thus, ensuring the drainage capacity and suppressing the increase in air resistance are incompatible with each other.

On the other hand, in Example 1, the following configurations (A), (B), and (C) were adopted.
(A) The first inner angle θ <b> 1 due to the front inclined wall 21 is set to be larger than the inflow angle of the traveling wind entering from the front side wall end portion 26 of the rear under cover 7.
(B) The drain port 73 opens in a rectangular shape along the outer peripheral shape of the front inclined wall 21, and the front end edge 73 a of the front side wall end portion 26 where the front inclined wall 21 starts to tilt upward. Set to.
(C) The width W of the wall surface 23a of the left side wall 23 and the wall surface 24a of the right side wall 24 facing in the vehicle width direction is set to be gradually narrowed from the front of the vehicle toward the rear of the vehicle.

  The operation of the configuration (A) will be described. The drain port 73 is opened to the front inclined wall 21 inclined by the first inner angle θ1. And 1st interior angle (theta) 1 is set to an angle larger than the inflow angle of the driving | running | working wind which enters into a hollow. Therefore, the traveling wind that has flowed into the depression from the front side wall end portion 26 has an effect of reaching the traveling wind rectifying surface 25 while drawing a streamline that gradually moves away from the drain port 73 as shown in FIG. In other words, the drainage port 73 is separated from the flow of the traveling wind, and the opening area of the drainage port 73 is allowed to expand.

  The operation of the configuration (B) will be described. With the configuration in which the drain port 73 is opened in a rectangular shape along the outer peripheral shape of the front inclined wall 21, a wider drain opening area can be ensured as compared with the case where only a part of the front inclined wall 21 is opened. Further, by setting the opening front end edge 73a of the drain port 73 in the region of the front side wall end portion 26, water or the like that is about to flow out from the front of the vehicle through the drain port 73 can be smoothly discharged from the front end edge 73a. Shows the action of discharging to the outside.

  The operation of the configuration (C) will be described. Since both wall surfaces 23a and 24a facing in the vehicle width direction have a tapered nozzle structure, the flow velocity of the traveling wind flowing along the traveling wind rectifying surface 25 is reduced toward the rear of the vehicle, as shown by the streamline in FIG. It gets faster and faster as you go. And the pressure of the exit area | region G of the drain port 73 falls with the increase in the flow velocity of driving | running | working wind, and a pressure difference generate | occur | produces inside and the outside of the drain port 73. This pressure difference shows the action of sucking out water or the like from the drain port 73 as indicated by an arrow E in FIG.

  As described above, the drainage means D of the first embodiment sets the drainage port 73 so as to be separated from the flow of the traveling wind, and aims to secure the drainage capacity from the drainage port 73 (A). The configuration of (B) and (C) was adopted. For this reason, during traveling, the drainage capacity corresponding to the demand can be ensured without affecting the rectifying action of the traveling wind.

[Inhibition of running resistance increase by drainage means]
An increase in running resistance due to the drainage means leads to an increase in air resistance D due to the underfloor and the entire tire, and therefore it is necessary to suppress an increase in running resistance due to the drainage means. Hereinafter, the traveling resistance increase suppressing action by the drainage means D provided on the rear under cover 7 of the first embodiment reflecting this will be described.

  As described above, in general, when the opening area of the drain hole is increased, the drainage capacity is increased, but when the running wind is taken into the drain hole, the flow of the traveling wind is disturbed around the drain hole, and the vortex The air resistance increases due to the structure. Thus, ensuring the drainage capacity and suppressing the increase in air resistance are incompatible with each other.

On the other hand, in Example 1, the following configurations (A), (D), and (E) were adopted.
(A) The first inner angle θ <b> 1 due to the front inclined wall 21 is set to be larger than the inflow angle of the traveling wind entering from the front side wall end portion 26 of the rear under cover 7.
(D) The second interior angle θ2 by the rear inclined wall 22 is set to an angle that suppresses the deflection of the streamlines of the traveling wind that passes from the traveling wind rectifying surface 25 to the rear side wall end portion 28 of the rear undercover 7.
(E) The traveling wind rectifying surface 25 is a wall surface of the rear inclined wall 22 having a flat surface 25a and an arc surface 25b.

  As described in [Effect of securing drainage ability by drainage means], the action of the above configuration (A) is that the drainage port 73 is separated from the flow of the running wind and the drainage port 73 is provided to the rectifying action of the running wind. The influence is suppressed and the degree of freedom in designing the rectifying structure is increased.

  The operation of the configuration (D) will be described. By setting the second interior angle θ2 to an angle that suppresses the deflection of the streamline of the traveling wind that passes through the rear side wall end portion 28, the flow of the traveling wind that passes through the rear side wall end portion 28 is subjected to separation or turbulence that becomes traveling resistance. It shows the effect of suppressing the occurrence.

  The operation of the configuration (E) will be described. By using the traveling wind rectifying surface 25 as the wall surface of the rear inclined wall 22 having the flat surface 25a and the circular arc surface 25b, the streamlines of the traveling wind passing to the rear side wall end portion 28 are disturbed as shown in FIG. It shows the effect that it can be drawn smoothly.

  As described above, the drainage means D of the first embodiment sets the drain port 73 at a position separated from the flow of the traveling wind, and aims to suppress the increase in air resistance (A), ( The configuration of D) and (E) was adopted. For this reason, it is possible to suppress a rise in air resistance to a minimum level while ensuring high drainage capacity through the water drain port 73.

  In addition, each effect | action in Example 1 is demonstrated about the drainage means D which opens the drainage port 73 provided in the rear under cover 7, and the other drainage ports 33, 34, 42, 43, 44, 72, and 74 are demonstrated. The explanation of the action of each drainage means that opens is omitted. However, each drainage means that opens the other drainage ports 33, 34, 42, 43, 44, 72, 74 also exhibits the same action as the above action.

Next, the effect will be described.
In the underfloor structure of the electric vehicle EV of the first embodiment, the effects listed below can be obtained.

(1) In a vehicle underfloor structure in which the under floor of the vehicle is covered with an under cover (rear under cover 7) and drainage means D is provided in the under cover (rear under cover 7).
The drainage means D is
A front-side slope in which the under cover (rear under cover 7) is inclined upward from the front side wall end portion 26 extending in the vehicle width direction toward the rear of the vehicle and penetrates at least a part of the wall to open the drain port 73. Wall 21;
The bent wall portion 27 connected to the front inclined wall 21 is inclined downward toward the rear side wall end portion 28 extending in the vehicle width direction of the under cover (rear under cover 7), and the flow of traveling wind is applied to the wall surface. A rear inclined wall 22 having a running wind rectifying surface 25 to be arranged;
With
The hollow shape in the vehicle front-rear direction from the under cover (rear under cover 7) is such that the first inner angle θ1 by the front inclined wall 21 is larger than the second inner angle θ2 by the rear inclined wall 22, and the two wall lengths L1 and L2 were made different.
For this reason, the aerodynamic performance of the vehicle as a whole can be achieved by suppressing the increase in air resistance while securing the drainage capacity from the undercover (rear undercover 7) during traveling.

(2) The first interior angle θ1 is set to be larger than the inflow angle of the traveling wind entering from the front side wall end portion 26 of the under cover (rear under cover 7).
For this reason, in addition to the effect of (1), the drainage port 73 is reliably cut off from the flow of the traveling wind, and even if the opening area of the drainage port 73 is enlarged, the influence on the rectifying action of the traveling wind is suppressed. Can do.

(3) The second interior angle θ2 is set to an angle that suppresses the deflection of the streamlines of the traveling wind passing from the traveling wind rectifying surface 25 to the rear side wall end portion 28 of the under cover (rear undercover 7).
For this reason, in addition to the effect of (1) or (2), it is possible to suppress the occurrence of separation or turbulent flow that causes running resistance in the flow of the running wind that passes to the rear side wall end portion 28.

(4) The drain port 73 has an opening front end edge 73a opened in the front inclined wall 21 set in a region of the front side wall end portion 26 where the front inclined wall 21 starts to tilt upward.
For this reason, in addition to the effects (1) to (3), it is possible to ensure the drainage ability to smoothly discharge water and the like from the drain port 73.

(5) The traveling wind rectifying surface 25 is a wall surface of the rear inclined wall 22, and includes a flat surface 25a from the bent wall portion 27 toward the rear side wall end portion 28, and the under cover (rear under cover 7). And a circular arc surface 25b that smoothly connects to the cover surface 7a.
For this reason, in addition to the effects (1) to (4), it is possible to smoothly draw the streamlines of the traveling wind that escapes to the rear side wall end portion 28 with a simple configuration without any disturbance.

(6) The drainage means D is a pair of triangles formed facing each other in the vehicle width direction by recessing the front inclined wall 21 and the rear inclined wall 22 from the under cover (rear under cover 7). A left side wall 23 and a right side wall 24 provided so as to close the shape space,
The left side wall 23 and the right side wall 24 are set so that the width W of the two wall surfaces 23a, 24a facing each other in the vehicle width direction is gradually narrowed from the front of the vehicle toward the rear of the vehicle.
For this reason, in addition to the effects of (1) to (5), the nozzle structure that increases the flow rate of the flow through the depression can provide a high drainage capacity with the action of sucking out water and the like from the drain port 73.

(7) The under cover (rear under cover 7) is a rear under cover 7 having a diffuser structure, and the drainage means D is disposed at an inlet position of the diffuser structure.
For this reason, in addition to the effects of (1) to (6), the diffuser structure that speeds up the flow velocity flowing backward along the cover surface 7a of the under cover (rear under cover 7) allows water or the like to be discharged from the drain port 73. A high drainage capacity with the action of sucking out can be obtained.

  As described above, the underfloor structure of the vehicle according to the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and the invention according to each claim of the claims is described. Design changes and additions are allowed without departing from the gist.

  In the first embodiment, the vehicle front-rear direction depression shape from the rear under cover 7 is such that the first inner angle θ1 due to the front inclined wall 21 is larger than the second inner angle θ2 due to the rear inclined wall 22, and the two wall lengths are An example of a different triangular depression shape was shown. However, as in the first embodiment, the front inclined wall and the rear inclined wall are not flat wall shapes, and if the angle condition and the wall length condition are satisfied, even if it is a quadratic curved wall shape or a cubic curved wall shape, good. That is, for example, the shape of the depression in the vehicle front-rear direction may be an asymmetric dome depression.

  In the first embodiment, the first interior angle θ1 is set larger than the inflow angle of the traveling wind entering from the front side wall end portion 26 of the rear under cover 7 and is set to an angle of about 50 ° in consideration of manufacturability by press molding. An example is shown. However, the setting angle of the first interior angle θ1 is not limited to about 50 °, and is set to an angle smaller than 50 ° or an angle larger than 50 °, for example, according to the design value of the inflow angle of the traveling wind. As an example. Furthermore, if there is no problem in manufacturing, it is preferable that the first inner angle θ1 is closer to 90 ° because the front inclined portion is separated from the flow of the traveling wind.

  In the first embodiment, the second interior angle θ2 is set to be about 13 °, which can suppress the deflection of the streamline of the traveling wind passing from the traveling wind rectifying surface 25 to the rear side wall end portion 28 of the rear undercover 7 and can be designed. An example of setting the angle is shown. However, the setting angle of the second interior angle θ2 is not limited to about 13 °. For example, it is set to an angle smaller than 13 ° or an angle larger than 13 ° according to the target value for suppressing the increase in running resistance. As an example. Furthermore, if there is no problem in design, the flow of the traveling wind can flow more smoothly as the second interior angle θ2 is closer to 0 °.

  In the first embodiment, the drainage port 73 is opened almost entirely along the shape of the front inclined wall 21 in consideration of manufacturability by press molding, and the opening front end edge 73a opened in the front inclined wall 21 is defined as the front side wall. The example set to the area | region of the edge part 26 was shown. However, the drain port may be an example that opens to a part of the front inclined wall 21 according to the required drainage capacity. Moreover, it is good also as an example which sets the opening front-end edge of a drain opening to an upper area | region rather than the front side wall edge part.

  In the first embodiment, the traveling wind rectifying surface 25 is the wall surface of the rear inclined wall 22, and the flat surface 25 a from the bent wall portion 27 toward the rear side wall end portion 28 and the cover surface 7 a of the rear under cover 7 are smooth. The example which has the circular arc surface 25b connected to is shown. However, the traveling wind rectifying surface may be obtained by providing a rectifying member as a separate member on the rear inclined wall 22 and obtaining it by the surface of the rectifying member. The traveling wind rectifying surface may be a flat surface, an arc surface, a curved surface, or a combination surface thereof.

  In the first embodiment, the drainage means D includes a left side wall 23 and a right side wall 24, and the width W of the two wall surfaces 23a, 24a facing each other in the vehicle width direction is gradually narrowed from the front of the vehicle toward the rear of the vehicle. An example of setting is shown. However, the drainage means may be an example in which there is no clear left side wall and right side wall by connecting the front side slope wall and the rear side slope wall to the under cover by a gentle curved surface change in the vehicle width direction. Furthermore, it is good also as an example which sets in the parallel surface which maintains the width W by two wall surfaces 23a, 24a uniformly, or makes the width W by the two wall surfaces 23a, 24a gradually wide toward the vehicle rear.

  In Example 1, the example which has arrange | positioned the drainage means D in the entrance position of the diffuser structure which the rear undercover 7 has was shown. However, the drainage means of the present invention may be provided in another under cover, such as the front under cover of the first embodiment.

  In the first embodiment, an example in which the underfloor structure of the present invention is applied to an electric vehicle EV is shown. However, the present invention can be applied to an underfloor structure of an electric vehicle such as a hybrid vehicle and a fuel cell vehicle as well as an underfloor structure of an engine vehicle. In addition, when applied to an electric vehicle equipped with a battery such as an electric vehicle EV, an improvement in power consumption performance can be achieved. In addition, when applied to an engine vehicle, fuel efficiency can be improved.

EV electric vehicle (electric vehicle, example of vehicle)
1L, 1R A pair of left and right front tires 2L, 2R A pair of left and right rear tires 3 Front under cover 31 Curved projection 33 Drain port 34 Drain port 4 Motor room rear under cover 42 Drain port 43 Drain port 44 Drain port 5 1st battery under cover 6 2nd battery under cover 7 Rear under cover (under cover)
7a Cover surface 71 Straightening ridge 72 Drain port 73 Drain port 73a Open front edge 74 Drain port 8L, 8R A pair of left and right front deflectors 9L, 9R A pair of left and right rear deflectors D Drainage means 21 Front inclined wall 21a Wall surface 22 Rear Side inclined wall 23 Left side wall 23a Wall surface 24 Right side wall 24a Wall surface 25 Rectifying surface 25a Flat surface 25b Arc surface 26 Front wall end portion 27 Bending wall portion 28 Rear side wall end portion CL Vehicle centerline θ1 First inner angle θ2 Second inner angle L1 Wall length L2 of front inclined wall 21 Wall length L3 of rear inclined wall 22 Depression length W Width by two wall surfaces 23a and 24a
FMAIN Mainstream flux of running wind

Claims (7)

Covering the under floor of the vehicle with an under cover, and in the under floor structure of the vehicle provided with drainage means in the under cover,
A curved protrusion is disposed at the vehicle front position from the front tire, at a substantially central portion in the vehicle width direction of the vehicle front portion across the vehicle center line of the under cover,
The drainage means is arranged at a position behind the curved protrusion from the curved protrusion so as to be separated from the curved protrusion ,
The drainage means is
A front inclined wall that inclines upward from the front side wall end portion extending in the vehicle width direction of the under cover toward the rear of the vehicle, and that penetrates at least a part of the wall and opens a drainage port;
Rear side having a traveling wind rectifying surface that slopes downward from a bent wall portion connected to the front inclined wall toward an end portion of a rear side wall extending in the vehicle width direction of the under cover, and adjusts a flow of traveling wind on the wall surface An inclined wall,
With
The hollow shape in the vehicle front-rear direction from the under cover is characterized in that the first inner angle by the front inclined wall is larger than the second inner angle by the rear inclined wall, and the two wall lengths are different. Under-floor structure of a vehicle. The vehicle underfloor structure according to claim 1,
The underfloor structure of a vehicle, wherein the first interior angle is set to be larger than an inflow angle of traveling wind entering from an end portion of a front side wall of the under cover. In the under-floor structure of the vehicle according to claim 1 or 2,
The underfloor structure of a vehicle, wherein the second interior angle is set to an angle that suppresses deflection of streamlines of traveling wind passing from the traveling wind rectifying surface to a rear side wall end portion of the under cover. In the underfloor structure of the vehicle according to any one of claims 1 to 3,
The underdrain structure for a vehicle, wherein the drain port has an opening front end edge opened in the front inclined wall set in a region of the front side wall end portion where the front inclined wall starts to tilt upward. In the underfloor structure of the vehicle according to any one of claims 1 to 4,
The running wind rectifying surface is a wall surface of the rear inclined wall, a flat surface from the bent wall portion toward the rear side wall end, an arc surface smoothly connected to the cover surface of the under cover, A vehicle under-floor structure characterized by comprising: In the underfloor structure of the vehicle according to any one of claims 1 to 5,
The drainage means includes a left side wall provided to close a pair of triangular spaces formed opposite to each other in the vehicle width direction by recessing the front inclined wall and the rear inclined wall from the under cover. A right side wall, and
An underfloor structure for a vehicle, wherein the left side wall and the right side wall are set so that a width by two wall surfaces facing each other in the vehicle width direction is gradually narrowed from the front of the vehicle toward the rear of the vehicle. In the underfloor structure of the vehicle according to any one of claims 1 to 6,
The under cover is a rear under cover having a diffuser structure, and the drainage means is disposed at an entrance position of the diffuser structure.

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