JP2011219042A - Underfloor structure of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underfloor structure of an electric vehicle which can improve aerodynamic performance as a whole vehicle by suppressing increase in air resistance while preventing a battery unit disposed in the underfloor from wetting.SOLUTION: In the underfloor structure of the electric vehicle EV, wherein a battery unit 16 disposed in the underfloor of the vehicle is covered with under covers 4, 5, 6 the battery under covers 4, 5, 6 include a motor room rear under cover 4 which covers a front extended region from a first battery under cover 5 and includes water draining means D1, D1 and D2. The draining means D1, D1 and D2 include a front side inclined wall 21 having drain ports 42, 43, 44 opened and a rear side inclined wall 22 having a traveling wind flow rectifying surface 25. A dent shape in a longitudinal direction of the vehicle from the motor room rear under cover 4 is formed such that a first interior angle θ1 by the front side inclined wall 21 is made larger than a second interior angle θ2 formed by the rear side inclined wall 22 and the lengths of two wall surface are made different.

Description

  The present invention relates to an underfloor structure for an electric vehicle in which a battery unit provided under a vehicle floor is covered with a battery under cover, and drainage means is provided on the battery under cover.

  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 which water cannot penetrate easily 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 it is possible to suppress an increase in air resistance, when a large amount of water or muddy water enters the under cover, the water that has entered from the outside can be reduced 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.

  It is assumed that this conventional underfloor structure is applied to a battery under cover that entirely covers a battery unit installed under the floor of an electric vehicle. In this case, water traveling from the road surface to the battery can be received by the battery under cover during traveling. However, when water enters the battery under cover from a motor room or the like, water exceeding the drainage capacity is collected in the tray-shaped battery under cover. Then, the water accumulated in the battery under cover moves to wet the battery unit.

  The present invention has been made paying attention to the above problems, and achieves an improvement in the aerodynamic performance of the vehicle as a whole by suppressing an increase in air resistance while preventing the battery unit placed under the floor from getting wet while traveling. An object of the present invention is to provide an underfloor structure for an electric vehicle that can perform the above.

In order to achieve the above object, in the under-floor structure of an electric vehicle according to the present invention, the battery unit provided under the under-floor of the vehicle is covered with a battery under cover.
In the underfloor structure, the battery under cover includes a battery cover portion that covers a planar projection region of the battery unit, and a front cover portion that covers a front extension region extending from the battery cover portion toward the front of the vehicle.
The front cover portion is provided with drainage means for draining water that has entered the cover from the outside toward the road surface.
The drainage means is inclined upward toward the rear of the vehicle, has a front inclined wall penetrating at least a part of the wall and opening a drain opening, is inclined downward from the front inclined wall, and runs on the wall surface. And a rear inclined wall having a traveling wind rectifying surface that regulates the flow of wind.
The hollow shape in the vehicle front-rear direction from the front cover portion 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.

In the present invention, when water or the like enters the front cover part, to prevent water accumulation in the front cover part and prevent the battery unit placed under the floor from getting wet, the drainage means provided in the front cover part can be used promptly. It is necessary to drain. On the other hand, in order to suppress an increase in air resistance despite the provision of the drainage means, it is necessary to smoothly flow the traveling wind along the front cover portion.
On the other hand, the drainage means opened a drain port in the front inclined wall with the first inner angle (> second inner angle). Even if the opening area of the drainage port is enlarged so that the traveling wind that flows into the depression draws a streamline that gradually moves away from the drainage port, the front side inclined wall captures the traveling wind and the battery unit from the road surface. It has an inclination angle (first interior angle) that suppresses the intake of water toward the. For this reason, the drainage effect | action which drains water in a cover rapidly from a drain port toward a road surface is shown.
On the other hand, the drainage means has a traveling wind rectifying surface on the rear inclined wall by the second interior angle (<first interior angle). The rear inclined wall has an inclination angle (second interior angle) that moderates the deflection of the flow of the traveling wind. For this reason, the running wind received by the running wind rectifying surface is adjusted so as to draw a smooth streamline, and the rectifying action for smoothly flowing the running wind from the depression to the cover surface is shown.
As described above, the aerodynamic performance of the vehicle as a whole can be achieved by suppressing the increase in air resistance while preventing the battery unit disposed under the floor from getting wet 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 an electric vehicle) to which the under-floor structure of Example 1 is applied. FIG. 4 is a perspective view of the motor room rear undercover in the underfloor structure of the first embodiment as viewed from the front side obliquely above the vehicle. It is the perspective view seen from the diagonally upper back side of the vehicle which shows the motor room rear part undercover in the underfloor structure of Example 1. FIG. It is a vertical side view which shows the vehicle body structure of the area | region in which the motor room rear part undercover was provided in the underfloor structure of Example 1. FIG. It is the figure seen from under the floor which shows the drainage means provided in the motor room rear under cover in the under floor structure of Example 1. It is the sectional view on the AA line of FIG. 5 which shows the drainage means provided in the motor room rear part undercover in the underfloor structure of Example 1. FIG. FIG. 6 is a cross-sectional view taken along the line B-B in FIG. 5, showing drainage means provided in the motor room 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. The flow of the driving | running | working wind which flows around the drainage means in which the drain hole 44 was opened in the electric vehicle to which the underfloor structure of Example 1 is applied, the flow of the drainage from a motor room, the flow of the water which goes to the battery from a road surface are shown. It is an operation explanatory view. In the electric vehicle to which the underfloor structure of the first embodiment is applied, the flow of running wind that flows around the drainage means in which the drainage opening 43 and the drainage opening 44 are opened, the flow of the drainage from the front suspension member, the drainage from the motor room It is effect | action explanatory drawing which shows the flow of water and the flow of the water which goes to the battery from a road surface. It is an effect explanatory view showing the flow of running wind to the drainage means provided in the motor room rear undercover in the underfloor structure of Example 1.

  Hereinafter, the best mode for realizing an underfloor structure of an electric vehicle according to 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 an electric 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 (front cover part), first battery under cover 5 (battery cover part), second battery under cover 6 (battery cover part), rear under cover 7, and a pair of left and right front deflectors 8L and 8R (rectification) Structure) and a pair of left and right rear deflectors 9L and 9R.

  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 fascia 11 to the front suspension member 14 (front suspension member: see FIG. 4). 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 protruding portion 31 (rectifying structure) 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 and two drain openings 33. , 34 are 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 the front suspension member 14 (see FIG. 4) to the rear part of the motor room 15 (see FIG. 4). A cover surface 4 a of the motor room rear under cover 4 is formed on 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 connected to each other in the central rear lower floor region from the rear part of the motor room 15 (see FIG. 4) to the rear end part of the battery unit 16 (see FIG. 4). It is the member which covers by doing. 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 battery undercovers 5 and 6 connect the front cover portion 4 that covers the planar projection area of the battery unit 16 (see FIG. 4) and covers the front extension area extending forward of the vehicle. That is, the motor room rear undercover 4 and the battery undercovers 5 and 6 are connected to each other, and the three undercovers 4, 5 and 6 are combined to constitute the battery undercover of the first embodiment.

  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 motor room rear undercover 4 in the underfloor structure of the first embodiment. Hereinafter, the configuration of the motor room rear undercover 4 will be described with reference to FIGS. 2 and 3.

  As shown in FIG. 2 and FIG. 3, the motor room rear under cover 4 has a tray shape that covers the central front underfloor region and collects water, muddy water, etc., and is integrated by press molding using a synthetic resin as a raw material. To be manufactured. The motor room rear under cover 4 is formed with four protrusions 41 extending in the vehicle front-rear direction. And the 1st drainage means D1, D1 (drainage means) which opened two drain holes 42 and 43 with a small opening area in the vehicle front side right-and-left position between the two protrusions 41 and 41 of the center part. Is provided. Moreover, the 2nd drainage means D2 (drainage means) which opened the one drainage port 44 with a large opening area in the vehicle rear side center position among the two protrusions 41 and 41 of a center part is provided. The motor room rear under cover 4 has a cover connecting groove 4b formed in the vehicle width direction at the rear end portion for connecting and connecting with the first battery under cover 5. Moreover, the bolt hole 4c is opened in the outer periphery position etc. The motor room rear under cover 4 is attached to the bottom of the center front floor by inserting and tightening bolts (not shown) into the plurality of bolt holes 4c.

  4-7 is a figure which shows the 1st drainage means D1 and D1 and the 2nd drainage means D2 which were provided in the motor room rear part undercover 4 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 draining means having the same configuration. Hereinafter, based on FIGS. 4-7, the structure of the 1st drainage means D1 and D1 in which the drain holes 42 and 43 were opened, and the 2nd drainage means D2 in which the drain hole 44 was opened is demonstrated.

  As shown in FIG. 4, the vehicle body structure in the region where the motor room rear under cover 4 is provided includes a motor room rear under cover 4, a front suspension member 14, a battery unit 16, a dash panel 17, and a floor panel. 18.

  The motor room rear under cover 4 is disposed between the front suspension member 14 and the battery unit 16, and has first drainage means D1 and D1 in which drain holes 42 and 43 are opened, and a drain hole 44 is opened. It has the 2nd drainage means D2.

  The front suspension member 14 is formed in a square shape with a closed cross-section beam structure, and elastically supports a pair of left and right suspension links.

  The battery unit 16 is configured by loading a battery cell stack, wiring, circuit board, and the like inside a battery case having a highly rigid structure and having a sealing property.

  The dash panel 17 is disposed in the vehicle width direction above the front suspension member 14 in the vehicle width direction, and the dash panel 17 is integrally connected to a floor panel 18 that constitutes a floor surface in the vehicle compartment extending rearward of the vehicle. The A motor room rear space that communicates with a motor room 15 in which a traveling motor (not shown) is installed is formed between the dash panel 17 and the floor panel 18 and the front suspension member 14.

  Here, since the 1st drainage means D1, D1 and the 2nd drainage means D2 are the same structures, below, the 2nd drainage means D2 is made into a representative example, and the detailed structure is demonstrated based on FIGS. .

  As shown in FIGS. 5 to 7, the second drainage means D2 includes a front inclined wall 21, a rear inclined wall 22, a left side wall 23, a right side wall 24, a drainage port 44, and a running wind rectifier. And a surface 25. That is, a recessed 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 at a position immediately before the battery unit 16 in the motor room rear under cover 4. The front inclined wall 21 has a drain hole 44, and the rear inclined wall 22 has a traveling wind rectifying surface 25.

  As shown in FIG. 6, 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 rear cover 4 of the motor room toward the rear of the vehicle, and penetrates at least a part of the wall. Thus, the drain port 44 is opened. The drainage port 44 opens in a rectangular shape that substantially conforms to the outer peripheral shape of the front inclined wall 21, and the opening front edge 44 a is set in a region of the front side wall end portion 26 where the front inclined wall 21 starts to tilt upward. is doing.

  As shown in FIG. 6, the rear inclined wall 22 faces 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 motor room rear undercover 4. It has a running air rectifying surface 25 that is inclined and adjusts the flow of the running wind on its wall surface. 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 smooth with respect to the cover surface 4a of the motor room rear undercover 4 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. And a circular arc surface 25b to be connected.

  As shown in FIG. 7, the left side wall 23 is formed in a pair facing the vehicle width direction by recessing the front inclined wall 21 and the rear inclined wall 22 bent from the motor room rear under cover 4. The triangular space is provided so as to close the left space.

  As shown in FIG. 7, the right side wall 24 is formed as a pair formed facing the vehicle width direction by recessing the front inclined wall 21 and the rear inclined wall 22 that are bent from the motor room rear under cover 4. Is set to close the right space.

  Here, as shown in FIG. 5, the left side wall 23 and the right side wall 24 are gradually narrowed in width W by two wall surfaces 23a, 24a facing each other in the vehicle width direction from the front of the vehicle toward the rear of the vehicle. is doing.

A hollow shape in the vehicle front-rear direction from the motor room rear undercover 4 by the front inclined wall 21 and the rear inclined wall 22 will be described.
The shape of the depression in the vehicle front-rear direction from the motor room rear under cover 4 is determined by the wall surface 21 a of the front inclined wall 21, the wall surface of the rear inclined wall 22 (running wind rectifying surface 25), and the cover surface 4 a of the motor room rear under cover 4. It is formed. And as shown in FIG. 6, it is set as the triangular hollow shape by which two wall surface length L1, L2 of the front side inclination wall 21 and the rear side inclination wall 22 was varied. 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 4a of the motor room rear undercover 4 is the travel of the rear inclined wall 22 with respect to the cover surface 4a of the motor room rear undercover 4. It is larger than the second inner angle θ2 formed by the wind rectifying surface 25. 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 length L1 of the front inclined wall 21 that opens the drainage port 44 is shortened, and the wall length L2 of the rear inclined wall 22 having 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 cover surface 4a of the motor room rear under cover 4. 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 °). Determined.

  Further, 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 cover surface 4a of the motor room rear undercover 4. The angle that suppresses the deflection of the streamlines of the traveling wind refers to an angle that secures the flow of traveling wind that suppresses the occurrence of separation, and the smaller the angle, the better. However, the second interior angle θ2 is determined to be, for example, an angle of 5 ° to 15 ° in consideration of the layout design because it is necessary to increase the length of the hollow in the vehicle front-rear direction as the angle becomes smaller.

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 this air resistance D, FIG. 8 shows a resistance 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 to a high level with the aim of extending the cruising distance, the improvement to reach the desired aerodynamic performance cannot be desired only by improving the vehicle styling.

  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 reduce the air resistance of the entire floor and tires, and to protect the battery in the case of an electric vehicle equipped with a battery unit under the floor, it is effective to provide an under cover that lowers the air resistance coefficient CD under the floor. It is. The undercover is provided with a drainage means to provide drainage, and the air resistance due to the provision of the drainage means while preventing the battery unit from getting wet by ensuring the drainage capacity of the drainage means. It is necessary to suppress the rise of

[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. 9, the electric vehicle EV covers almost the entire area under the floor excluding 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 underfloor center part underfloor region is reduced by the orderly and smooth running wind flowing through the underfloor center part underfloor region from the vehicle front end to the vehicle rear end.

  As shown in FIG. 9, 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. 9, 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. 9, the electric vehicle EV includes a curved protrusion 31 that controls 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 in from the front end of the vehicle is collected in the central underfloor area under the front floor, and the air resistance D in the central underfloor area 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 EV, 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 provided in the under cover It is. Hereinafter, the drainage action and the traveling wind rectifying action by the first drainage means D1, D1 and the second drainage means D2 provided in the motor room rear undercover 4 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 under cover is a tray shape that collects water or muddy water that has entered from the outside, a draining means is required, and is generally performed by 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 first drainage means D1, D1 and the second drainage means D2 having the drainage port 73 in the front inclined wall 21 and the traveling wind rectifying surface 25 in the rear inclined wall 22 are employed.

  For this reason, during traveling, the traveling wind flowing along the cover surface 4a of the motor room rear under cover 4 flows into the recess from the front side wall end portion 26 extending in the vehicle width direction of the motor room rear under cover 4. Then, when the traveling wind flows into the depression, as shown in FIG. 10, the traveling wind rectifying surface 25 of the rear inclined wall 22 receives and the received traveling wind flow is deflected by a gradual angle change, and the traveling wind rectification is performed. It is arranged to draw a smooth streamline F along the surface 25. Then, the rear side wall end portion 28 extending in the vehicle width direction of the motor room rear under cover 4 passes smoothly without being peeled off, and is again caused to flow out to the cover surface 4 a of the motor room rear under cover 4.

  At this time, the shape of the depression is defined by a first inner angle θ1 formed by the wall surface 21a of the front inclined wall 21 with respect to the cover surface 4a and a second inner angle θ2 formed by the wall surface 22a of the rear inclined wall 22 with respect to the cover surface 4a. It was a big angle and the two wall lengths were different. 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 F that gradually moves away from the drain port 44 as shown in FIG.

  As described above, even if the opening area of the drainage port 44 is enlarged, the intake of traveling wind is suppressed, and the intake of water from the road surface to the battery unit 16 is suppressed as shown by the arrow H in FIG. The front inclined wall 21 is opened. For this reason, as shown by an arrow E in FIG. 10, even if a large amount of water, muddy water, or the like has entered the motor room rear under cover 4 from the outside of the cover, the drainage action is to drain quickly. That is, the drainage capacity from the motor room rear under cover 4 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. For this reason, as shown by the streamline F in FIG. 10, even if the flow velocity of the traveling wind flowing through the depression is high, the rectifying action is arranged so as to draw a streamline that does not cause separation or turbulent flow. That is, the traveling wind smoothly flows along the motor room rear under cover 4 and the increase in air resistance is suppressed.

  As described above, the first drainage means D1 and D1 and the second drainage means D2 of the first embodiment have the front inclined wall 21 having the drain ports 42, 43, and 44 and the traveling wind rectifying surface 25. And a side inclined wall 22. The shape of the recess in the vehicle longitudinal direction is a shape in which 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 different. For this reason, while driving | running | working, as a result of suppressing the raise of air resistance, ensuring the drainage capability from the motor room rear part undercover 4, the improvement of the aerodynamic performance as the whole vehicle can be achieved.

[Ensuring drainage capacity by drainage means]
In order to protect the battery unit covered by the under cover from the influence of water, the drainage means needs to ensure the drainage capacity required for rainy road traveling or the like. Hereinafter, the drainage capacity ensuring action by the first drainage means D1, D1 and the second drainage means D2 provided in the motor room rear undercover 4 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. In addition, in order to protect the battery unit 16 from getting wet, the motor room rear under cover 4 has a drainage capacity for quickly draining water entering from the motor room 15 and water entering over the front suspension member 14. Is required.

On the other hand, in Example 1, the following configurations (A), (B), (C), and (D) were adopted.
(A) The first inner angle θ1 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 motor room rear undercover 4.
(B) The drainage opening 44 opens in a rectangular shape along the outer peripheral shape of the front inclined wall 21, and the opening front end edge 44 a is a region of the front side wall end portion 26 where the front inclined wall 21 starts to tilt upward. Set to.
(C) The drainage means includes first drainage means D1 and D1 disposed immediately after the front suspension member 14, and second drainage means D2 disposed immediately before the battery unit 16. And the drainage opening area of the 2nd drainage means D2 was set wider than the drainage opening area of the 1st drainage means D1 and D1.
(D) The drainage means is disposed in the area of the main stream line bundle FMAIN of the traveling wind passing through the center part under the floor centering on the vehicle center line CL in the motor room rear under cover 4.

  The operation of the configuration (A) will be described. The drain port 44 is opened to the front inclined wall 21 that is 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. For this reason, the traveling wind that has flowed into the depression from the front side wall end portion 26 has an action of reaching the traveling wind rectifying surface 25 while drawing a streamline F gradually moving away from the drain port 44 as shown in FIG. In other words, the drainage port 44 is disconnected from the flow of the traveling wind, and the opening area of the drainage port 44 is allowed to expand.

  The operation of the configuration (B) will be described. With the configuration in which the drainage port 44 is opened in a rectangular shape along the outer peripheral shape of the front inclined wall 21, a wider drain opening area can be secured as compared with the case where only a part of the front inclined wall 21 is opened. In addition, by setting the front opening edge 44a of the drainage port 44 in the region of the front side wall end portion 26, water or the like that flows from the front of the drainage flow vehicle through the drainage port 44 is smoothly discharged to the outside. Shows the effect of

The operation of the configuration (C) will be described. As shown in FIG. 11, water entering the motor room rear under cover 4 from the outside has a low flow rate of water E1 entering over the front suspension member 14, and water E2 having a high flow rate of entering from the motor room 15. There is. If this intrusion water is to be drained by a single draining means, a draining means having a wide opening area of the drain port is provided at the center of the motor room rear undercover 4 in the vehicle front-rear direction. However, in this case, the depth of the recess from the motor room rear under cover 4 is increased, which is disadvantageous in terms of running resistance. Further, the water that has entered the position immediately before the battery unit 16 cannot be drained, which is disadvantageous in terms of water protection performance that protects the battery unit 16 from getting wet.
On the other hand, the drainage of the water E1 having a small flow rate entering the front suspension member 14 is shared by the first drainage means D1 and D1, and the drainage of the water E2 having a large flow rate entering from the motor room 15 is It was made to share in 2 drainage means D2. For this reason, compared with the case where it is going to drain with one discharge means, when draining with the 1st drainage means D1, D1 and the 2nd drainage means D2, the hollow depth from motor room rear part undercover 4 becomes shallow. This is advantageous in terms of running resistance. Further, the water E1 that has entered at the position immediately after the front suspension member 14 is drained by the first drainage means D1 and D1, and the water E2 that has entered at the position immediately before the battery unit 16 is drained by the second drainage means D2. At this time, the drain opening area of the drain port 44 of the second drainage means D2 is set wider than the total drain opening area of the drain ports 42 and 43 of the first drain means D1 and D1. Therefore, the 1st drainage means D1, D1 and the 2nd drainage means D2 show the double drainage effect | action of draining with the drainage capability corresponding to the different flow volume of the water E1 and E2 which permeate.

The operation of the configuration (D) will be described. The underfloor structure of the first embodiment collects traveling wind flowing in from the front end of the vehicle in the central underfloor region, and as a rectifying structure for guiding it to the motor room rear undercover 4, a pair of left and right front deflectors 8L and 8R, and a curved protrusion 31 It is equipped with. For this reason, the flow velocity of the traveling wind is the fastest in the region of the main stream line bundle FMAIN of the traveling wind passing through the center part below the floor centering on the vehicle center line CL.
Therefore, as shown by the streamline in FIG. 12, the pressure in the outlet region G of the drain holes 42, 43, 44 decreases with the high flow velocity of the traveling wind, and the inside of the drain holes 42, 43, 44 There is a pressure difference between the outside and the outside. This pressure difference shows the action of sucking out water and the like from the drain port 44 as indicated by an arrow E in FIG.

  As described above, the first drainage means D1, D1 and the second drainage means D2 of the first embodiment set the drainage ports 42, 43, 44 so as to be separated from the flow of the traveling wind, and the drainage port. The above configurations (A), (B), (C), and (D) were adopted with the aim of securing drainage capacity from 42, 43, and 44. 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, a description will be given of the traveling resistance increase suppressing action by the first drainage means D1, D1 and the second drainage means D2 provided in the motor room rear undercover 4 of the first embodiment reflecting this.

  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), (E), and (F) were adopted.
(A) The first inner angle θ1 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 motor room rear undercover 4.
(E) 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 cover surface 4a of the motor room rear undercover 4.
(F) 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 [Effects for securing drainage capacity by drainage means], the action of the above configuration (A) is that the drain holes 42, 43, 44 are separated from the flow of the traveling wind, and the drainage is given to the rectifying action of the traveling wind. The influence of the presence of the ports 42, 43, 44 is suppressed, and the degree of freedom in designing the rectifying structure is increased.

  The operation of the configuration (E) will be described. Since the second interior angle θ2 is set 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 that travels through the cover surface 4a of the rear under cover 4 of the motor room becomes a running resistance separation. And the action of suppressing the occurrence of turbulence.

  The operation of the configuration (F) 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 streamline of the traveling wind passing to the rear side wall end portion 28 is shown by the streamline F in FIG. As described above, the effect of being able to draw smoothly without disturbance is shown.

  As described above, the first drainage means D1, D1 and the second drainage means D2 of the first embodiment set the drainage ports 42, 43, 44 at positions separated from the flow of the traveling wind, and The above-mentioned configurations (A), (E), and (F) were adopted with the aim of suppressing the rise in air resistance. For this reason, it is possible to suppress the increase in air resistance to a minimum level while ensuring high drainage capacity through the drain ports 42, 43, 44.

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 an underfloor structure of an electric vehicle in which a battery unit 16 mounted under the vehicle floor is covered with a battery under cover,
The battery under cover includes a battery cover portion (first battery under cover 5 and second battery under cover 6) that covers a planar projection region of the battery unit 16, and the battery cover portion (first battery under cover 5 and second battery cover 16). A front cover portion (motor room rear under cover 4) covering a front extension region extending from the battery under cover 6) to the front of the vehicle,
Drainage means (first drainage means D1, D1, second drainage means D2) for draining the water that has entered the cover from the outside toward the road surface is provided in the front cover part (motor room rear undercover 4). ,
The drainage means (the first drainage means D1, D1, the second drainage means D2) are inclined upward toward the rear of the vehicle and pass through at least a part of the wall to open the drain holes 42, 43, 44. The front inclined wall 21 and the rear inclined wall 22 which has a traveling wind rectifying surface 25 which is inclined downward from the front inclined wall 21 and regulates the flow of traveling wind on the wall surface thereof,
The hollow shape in the vehicle front-rear direction from the front cover part (motor room rear under cover 4) 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. Two wall lengths were varied.
For this reason, the improvement of the aerodynamic performance of the entire vehicle can be achieved by suppressing the increase in air resistance while preventing the battery unit 16 disposed under the floor from getting wet while traveling.

(2) The first interior angle θ1 is set to be larger than the inflow angle of the traveling wind entering from the cover surface 4a of the front cover part (motor room rear under cover 4).
For this reason, in addition to the effect of (1), the drainage ports 42, 43, 44 are reliably separated from the flow of the traveling wind, and even if the opening area of the drainage ports 42, 43, 44 is enlarged, The influence on the rectifying action can be suppressed.

(3) The second interior angle θ2 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 cover surface 4a of the front cover portion (motor room rear undercover 4).
For this reason, in addition to the effect of (1) or (2), the flow of the traveling wind passing through the cover surface 4a of the front cover part (motor room rear under cover 4) may cause separation or turbulent flow that becomes traveling resistance. Can be suppressed.

(4) The front cover portion (motor room rear under cover 4) is a cover portion that covers a region from the vehicle rear position of the front suspension member (front suspension member 14) to the vehicle front position of the battery unit 16,
The drainage means includes first drainage means D1 and D1 disposed immediately after the front suspension member (front suspension member 14) in the front cover portion (motor room rear undercover 4), and the battery unit 16. Second drainage means D2 disposed at the immediately preceding position.
For this reason, in addition to the effects of (1) to (3), the double drainage action corresponding to the water intrusion route ensures a high drainage capacity without collecting water in the front cover (motor room rear undercover 4). can do.

(5) The drainage means sets the drainage opening area of the second drainage means D2 wider than the drainage opening area of the first drainage means D1 and D1.
For this reason, in addition to the effect of (4), the water entering the front cover (motor room rear under cover 4) can be efficiently drained by setting the drain opening area corresponding to the flow rate for each water intrusion route. Can do.

(6) A rectifying structure (front deflectors 8L and 8R, curved protrusion 31) that collects the traveling wind flowing in from the front end of the vehicle in a central underfloor region and guides it to the front cover (motor room rear undercover 4),
The drainage means (first drainage means D1, D1 and second drainage means D2) are traveling winds that pass through the center part below the floor centered on the vehicle center line CL in the front cover part (motor room rear undercover 4). Placed in the area of the mainstream flux FMAIN.
For this reason, in addition to the effects of (1) to (5), drainage means (first drainage means D1, D1, second drainage means D2) in the area of the mainstream line bundle FMAIN through which traveling wind flows at the fastest flow velocity under the floor. ) Is provided, it is possible to obtain a high drainage capacity to which an action of sucking out water or the like from the drain ports 42, 43, 44 is added.

  As mentioned above, although the underfloor structure of the electric vehicle of this invention has been demonstrated based on Example 1, it is not restricted to this Example 1 about a concrete structure, The invention which concerns on each claim of a claim Design changes and additions are permitted without departing from the gist of the present invention.

  In the first embodiment, the shape of the recess in the vehicle front-rear direction from the motor room rear under cover 4 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 An example of triangular depressions with different thicknesses 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 larger than the inflow angle of traveling wind entering from the front side wall end portion 26 of the motor room rear undercover 4 and is set to an angle of about 50 ° in consideration of manufacturability by press molding. An example of setting 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 is possible to suppress the deflection of the streamline of the traveling wind passing from the traveling wind rectifying surface 25 to the cover surface 4a of the rear under cover 4 of the motor room and possible in design 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 ports 42, 43, 44 are 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 opened to the front inclined wall 21 The example which sets 44a to the area | region of the front side wall 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 running 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 4 a of the motor room rear undercover 4 are provided. The example which has the circular arc surface 25b connected smoothly with respect to was 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 includes the left side wall 23 and the 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 was given. 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 the first embodiment, as the battery under cover, the battery cover part is divided into two parts, the first battery under cover 5 and the second battery under cover 6, and the front cover part is divided into three as the motor room rear under cover 4. Indicated. However, the battery cover part may be divided into two parts as one battery under cover and the front cover part as one motor room rear under cover 4. Furthermore, it is good also as an example made into an integrated battery under cover, without dividing a battery cover part and a front cover part.

  In the first embodiment, the first drainage means D1 and D1 are disposed at the vehicle front position of the motor room rear undercover 4 and the second drainage means D2 is disposed at the vehicle rear position (of the battery unit 16 of the motor room rear undercover 4). An example of arrangement at the immediately preceding position) is shown. However, if one or more drainage means of the present invention are provided in the front cover part in order to protect the battery unit from the influence of water, the number of drainage means, the layout, the opening area setting of the drainage port, The present invention is not limited to those shown in the first embodiment.

  In the first embodiment, an example using the front deflectors 8L and 8R and the curved protrusion 31 is shown as a rectifying structure that collects the traveling wind flowing in from the front end of the vehicle in the central under floor area and guides it to the rear under cover 4 of the motor room. However, the rectifying structure is not limited to this as long as the traveling wind flowing in from the front end of the vehicle is collected in the central underfloor region. For example, only the front deflector or only the curved protrusion is used. It is also possible to use a structure using another rectifying structure, or using another rectifying combination structure.

  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 also be applied to an underfloor structure of an electric vehicle in which a battery (secondary battery) is mounted under the floor such as a hybrid vehicle or a fuel cell vehicle. In addition, when applied to an electric vehicle equipped with a battery such as an electric vehicle EV, the cruising distance is extended, and an improvement in power consumption performance can be achieved.

EV electric vehicle (an example of an electric 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 protrusion (rectifying structure)
33 Drain port 34 Drain port 4 Motor room rear under cover (front cover)
4a Cover surface 42 Drain port 43 Drain port 44 Drain port 5 First battery under cover (battery cover part)
6 Second battery under cover (battery cover)
7 Rear under cover 7a Cover surface 71 Straightening ridge 72 Drainage port 73 Drainage port 73a Open front edge 74 Drainage ports 8L, 8R A pair of left and right front deflectors (rectification structure)
9L, 9R A pair of left and right rear deflectors D1 first drainage means (drainage means)
D2 Second drainage means (drainage means)
21 Front side 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 side wall end portion 27 Bending wall portion 28 Rear side wall end portion CL Vehicle centerline θ1 1st interior angle (theta) 2 2nd interior angle L1 Wall surface length L2 of the front side inclination wall 21 Wall surface length L3 of the back side inclination wall 22 Depression length W Width by two wall surfaces 23a and 24a
FMAIN Mainstream flux of running wind

Claims (6)

In the underfloor structure of an electric vehicle in which the battery unit installed under the vehicle floor is covered with a battery under cover,
The battery under cover includes a battery cover portion that covers a planar projection region of the battery unit, and a front cover portion that covers a front extension region extending forward from the battery cover portion to the vehicle front,
The front cover portion is provided with drainage means for draining water that has entered the cover from the outside toward the road surface,
The drainage means is inclined upward toward the rear of the vehicle, has a front inclined wall penetrating at least a part of the wall and opening a drain opening, is inclined downward from the front inclined wall, and runs on the wall surface. A rear inclined wall having a running wind rectifying surface that regulates the flow of wind,
A hollow shape in the vehicle front-rear direction from the front cover portion 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 for electric vehicles. In the underfloor structure of the electric vehicle according to claim 1,
The underfloor structure of an electric vehicle, wherein the first interior angle is set to be larger than an inflow angle of traveling wind entering from a cover surface of the front cover portion. In the underfloor structure of the electric vehicle according to claim 1 or 2,
The under-floor structure of an electric vehicle, wherein the second interior angle is set to an angle that suppresses deflection of a stream line of traveling wind passing from the traveling wind rectifying surface to a cover surface of the front cover portion. In the underfloor structure of the electric vehicle according to any one of claims 1 to 3,
The front cover portion is a cover portion that covers a region from a vehicle rear position of the front suspension member to a vehicle front position of the battery unit,
The drainage means includes: a first drainage means disposed immediately after the front suspension member in the front cover portion; and a second drainage means disposed immediately before the battery unit. Underfloor structure for electric vehicles. In the underfloor structure of the electric vehicle according to claim 4,
An underfloor structure for an electric vehicle, wherein the drainage means has a drainage opening area of the second drainage means wider than a drainage opening area of the first drainage means. In the underfloor structure of the electric vehicle according to any one of claims 1 to 5,
Collecting the traveling wind flowing in from the front end of the vehicle in a central lower floor area, and having a rectifying structure that leads to the front cover part,
An underfloor structure for an electric vehicle, wherein the drainage means is disposed in a region of a mainstream line bundle of traveling wind passing through a center portion below the floor centering on a vehicle center line in the front cover portion.

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