JP2020040610A - Vehicle undercarriage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the reduction of the rectification effect of a rear under cover behind the rear suspension member even if the cover under the rear suspension member is omitted. A battery under cover covers a bottom surface of a battery pack. The rear under cover 10 extends from the lower rear portion of the rear suspension member 30 to the lower end of the rear bumper guard 60. The rear end of the battery under cover 40 and the front end of the rear under cover 10 are separated from each other, and the rear suspension member 30 is exposed to the road surface in the separated region. A bottom surface 11 of the rear under cover 10 facing the road surface is a curved surface that is convex downward. Due to the curved shape of the bottom surface 11, a so-called Coanda effect occurs, and the streamline of the air follows the bottom surface of the rear under cover 10. [Selection diagram]

Description

  In the present specification, a vehicle lower structure including an undercover on a vehicle bottom surface is disclosed.

  As disclosed in Patent Literature 1 and the like, an under cover is provided on a vehicle bottom surface in order to improve aerodynamic characteristics of the vehicle. By providing the undercover, the vehicle bottom surface becomes flat, and turbulence of the air flowing through the vehicle bottom surface is suppressed as compared with the case where air is received on the surface of a vehicle component such as an engine or an exhaust pipe provided under the vehicle.

  For example, the undercover is provided from the front end to the rear end of the vehicle bottom surface. FIG. 5 illustrates a bottom view of the rear of the vehicle. FIG. 5 illustrates a bottom view of the electric vehicle in which the battery pack 200 is mounted below the floor panel of the vehicle.

  The undercover includes a battery undercover 202 provided below the battery pack 200, a rear suspension undercover 203 provided below the rear suspension member 201, and a rear undercover 204 connected to the rear end of the rear suspension undercover 203. It consists of. The rear end of the rear under cover 204 is connected to a rear bumper guard 206 at the rear end of the vehicle.

  As illustrated by the stream line L3 in FIG. 6, the air flowing under the vehicle flows along the lower surfaces of the battery undercover 202, the rear suspension undercover 203, and the rear undercover 204. By providing the undercover in this manner, formation of an air vortex under the vehicle, separation of air from the vehicle bottom surface, and the like are suppressed, so that the aerodynamic characteristics of the vehicle are improved.

JP 2010-13051 A

  By the way, the rear suspension under cover 203 is arranged close to the rear wheel 207 in the vehicle width direction, so that foreign matter wound around the rear wheel 207 easily enters the upper surface of the cover. For example, mud or snow rolled up by the rear wheel 207 enters the upper surface of the rear suspension undercover 203. If the foreign matter that has entered the upper surface accumulates, the weight of the foreign object may cause the rear suspension under cover 203 to fall off.

  Therefore, it is conceivable to expose the rear suspension member 201 without mounting the rear suspension under cover 203 on the vehicle from the beginning. However, in this case, as illustrated by the streamline L4 in FIG. 7, the air that has passed through the battery undercover 202 hits the front wall 204A of the rear undercover 204 to form an air vortex or separates from the rear undercover 204. For example, the rectification effect of the rear under cover 204 may not be obtained.

  Therefore, an object of the present invention is to provide a vehicle lower structure capable of suppressing a reduction in a rectifying effect of a rear undercover behind the rear suspension member even when a cover under the rear suspension member is omitted.

  The vehicle lower structure disclosed in this specification includes a battery pack, a rear suspension member, a rear bumper guard, a battery under cover, and a rear under cover. The battery pack is installed below the floor panel. The rear suspension member is provided behind the battery pack in the vehicle length direction, and supports a rear wheel suspension mechanism. The rear bumper guard is provided at the rear end of the vehicle. The battery under cover covers a bottom surface of the battery pack. The rear under cover extends from a lower rear portion of the rear suspension member to a lower end of the rear bumper guard. The rear end of the battery undercover and the front end of the rear undercover are separated from each other, and the rear suspension member is exposed to the road surface in the separated area. The bottom surface of the rear under cover facing the road surface is a curved surface that is convex downward.

  According to the above configuration, the streamline of the air along the bottom surface of the battery undercover separates from the rear end of the battery undercover. Due to the Coanda effect, the streamlines of the air follow the bottom surface of the rear undercover.

  According to the vehicle lower structure disclosed in this specification, even when the cover under the rear suspension member is omitted, it is possible to suppress the reduction of the rectifying effect of the rear under cover behind the rear suspension member.

FIG. 3 is a bottom view illustrating a bottom surface behind the vehicle. It is a figure which illustrates the AA section of FIG. It is the figure which added the streamline of the air to the AA cross section of FIG. It is a figure explaining a Coanda effect. It is a bottom view which illustrates the bottom surface of the conventional vehicle back. FIG. 6 is a diagram illustrating a BB cross section of FIG. 5. FIG. 6 is a cross-sectional view taken along line BB of FIG. 5, showing a streamline of air when a rear suspension undercover is removed.

  FIG. 1 illustrates a bottom view of the vehicle lower structure according to the present embodiment. FIG. 2 illustrates an AA cross-sectional side view of FIG. 1. FIG. 3 illustrates a cross-sectional view of FIG. 2 in which air streamlines are added.

  1 to 3, the vehicle length direction (vehicle front-rear direction) is indicated by an axis represented by a symbol FR, the vehicle width direction is indicated by an axis represented by a symbol RW, and the vehicle height direction is indicated by a symbol UP. The axis is shown. The vehicle longitudinal axis FR assumes the forward direction of the vehicle as the positive direction. The right width direction of the vehicle width axis RW is defined as a positive direction. In addition, the vehicle height axis UP assumes that the upward direction is the positive direction. These three axes are orthogonal to each other.

  The vehicle illustrated in FIGS. 1 to 3 is an electric vehicle using a rotating electric machine as a driving source and a battery pack 20 as a power source. As illustrated in FIGS. 1 and 2, the rear end of the vehicle bottom surface is covered with a rear under cover 10 over the entire width in the vehicle width direction, and has a structure without an exhaust pipe.

  The vehicle lower structure according to the present embodiment includes a battery pack 20, a rear suspension member 30, a rear bumper guard 60, a battery undercover 40, and a rear undercover 10.

  1 to 3, the battery pack 20 is installed under the floor, that is, under the floor panel. Battery pack 20 is relatively large, and has an area occupying most of the area under the floor of the passenger compartment. For example, the battery pack 20 extends from a front suspension member (not shown) to a rear suspension member 30 shown in FIGS.

  The battery pack 20 includes a pack cloth (not shown) which is a frame member extending on the lower surface thereof, for example, in a vehicle width direction. ) Are fastened by bolts and nuts. Thus, the battery pack 20 is suspended and supported by the vehicle.

  A rear suspension member 30 is provided behind the battery pack 20 in the vehicle length direction. The rear suspension member 30 is a ladder-like reinforcing member extending in the vehicle width direction, and includes a front cross 31, a rear cross 32, and a pair of side rails 33. The front cross 31 extends in the vehicle width direction, and the rear cross 32 is provided behind the front cross 31 in the vehicle length direction and extends in the vehicle width direction. The pair of side rails 33 extend in the vehicle length direction and connect the front cross 31 and the rear cross 32.

  The rear suspension member 30 supports a rear suspension mechanism that is a suspension mechanism for the rear wheel 70. For example, the rear suspension mechanism is a double wishbone rear suspension, and a lower arm 80 which is a typical part thereof is illustrated in FIG.

  The inner end of the lower arm 80 in the vehicle width direction is supported by the rear suspension member 30. The support portion is a rotation support portion 81, and the lower arm 80 is rotatable around the rotation support portion 81 in the vehicle height direction (vertical direction).

  Further, both ends in the vehicle width direction of the rear suspension member 30 are fastened and supported by rear side members 85 which are frame members of the vehicle. For example, outer ends of the front cross 31 and the rear cross 32 on the vehicle width direction are fastened to the rear side member 85.

  A vehicle rear end portion behind the rear suspension member 30 in the vehicle length direction is a vehicle rear end portion, and a rear bumper guard 60 is provided at the rear end portion. The rear bumper guard 60 is made of, for example, a resin material such as an ABS resin.

  2, rear bumper guard 60 is connected at its lower end to bottom surface 62 extending substantially horizontally (RW-FR plane) and to the rear end of bottom surface 62 in the vehicle length direction and in the vehicle height direction. The vehicle has a substantially L-shaped cross-section including a vehicle rear end surface 61 that extends from the vehicle. The rear bumper guard 60 is provided so as to surround the bumper reinforce 50, for example. The bumper reinforcement 50 is a reinforcing member connected to the rear end of the rear side member 85 and extending in the vehicle width direction. Referring to FIG. 1, a rear fog lamp mechanism 90 is provided at the center of the rear bumper guard 60 in the vehicle width direction of the rear end face 61 of the vehicle.

  The vehicle bottom is covered with an undercover. The undercover includes a battery undercover 40 and a rear undercover 10.

  The battery under cover 40 is provided below the battery pack 20 and covers the bottom surface of the battery pack 20. As illustrated in FIG. 1, the rear end of the battery undercover 40 may have a tapered shape such that the width of the vehicle becomes shorter toward the rear in the vehicle length direction. Further, the rear end may overlap a part of the rear suspension member 30, for example, a part of the front cloth 31 when viewed from below.

  As illustrated in FIG. 2, the battery under cover 40 has a boat-shaped structure, and has a bottom surface 41 extending along a horizontal plane (RW-FR plane), and is connected to a rear end of the bottom surface 41 and substantially in a vehicle height direction. And a rear side surface 43 that extends from the rear side. Further, the rear end portion 41A of the bottom surface 41 may have an inclined cross-sectional shape such that the rear end portion 41A is lifted up (raised) toward the rear in the vehicle length direction.

  The rear under cover 10 extends from a lower rear portion of the rear suspension member 30 to a lower end of the rear bumper guard 60. Referring to FIG. 1, for example, a rear undercover 10 is configured to include a pair of cover pieces 10A and 10B that are divided at a center in the vehicle width direction as a boundary. In such a configuration, when one of the pair of cover pieces 10A and 10B is removed from the vehicle body, a rear fog valve (shown in the drawing) provided as a light bulb part of the rear fog lamp mechanism 90 and provided on the inside (back side) of the rear bumper guard 60 in the vehicle. Can be exchanged.

  Referring to FIG. 2, the rear end in the vehicle length direction of bottom surface 11 of rear undercover 10 is connected to the front end of bottom surface 62 of rear bumper guard 60. Further, the front end of the rear under cover 10 may be installed so as not to overlap the rear cross 32 which is a rear member of the rear suspension member 30 when viewed from below. Referring to FIG. 1, the front end of rear undercover 10 is formed to have a tapered shape in which the vehicle width direction becomes narrower, for example, as going forward in the vehicle length direction.

  1 and 2, the vehicle lower structure according to the present embodiment has a structure in which an undercover, for example, a rear suspension undercover is not provided between the battery undercover 40 and the rear undercover 10. Therefore, the rear side surface 43, which is the rear end of the battery undercover 40, and the front side surface 12, which is the front end of the rear undercover 10, are separated from each other, and the rear suspension member 30 is exposed to the road surface in the separated area.

  As shown by the dashed line in FIG. 2, the front end of the bottom surface 11 of the rear under cover 10 facing the road surface is longer than the extension line extending rearward in the vehicle length direction from the rear end portion 41A of the battery under cover 40. It is provided above in side view. With such a positional relationship, the air separated from the rear end portion 41 </ b> A of the battery undercover 40 is prevented from colliding with the front side surface 12 of the rear undercover 10.

  Further, the bottom surface 11 of the rear under cover 10 is formed so as to have a downwardly curved surface. For example, the bottom surface 11 of the rear under cover 10 has a curved surface shape that gradually lifts (rises) from the front end to the rear end, and is formed so that the curved surface is convex downward.

  By providing such a downwardly convex curved surface shape, the Coanda effect occurs, and air flows along the bottom surface 11. FIG. 4 is a diagram illustrating the Coanda effect. In general, a fluid has a property of flowing along a curved surface 100 having a convex cross section (Coanda effect). For example, with respect to the streamline L2 in FIG. 4, the fluid tends to proceed in a linear direction as indicated by a broken arrow due to its inertia. At this time, the pressure in the region 102 surrounded by the ellipse beside the broken arrow becomes relatively low. Due to this pressure difference, the fluid is pulled toward the low pressure area 102 side. As a result, the fluid flows along the curved surface 100.

  The bottom surface 11 of the rear under cover 10 according to the present embodiment has a downwardly convex curved shape utilizing such a Coanda effect in the vehicle lower part structure. Referring to FIG. 3, air flowing along the bottom surface 41 of the battery under the battery under cover 40 in a region rearward in the vehicle length direction from the rear end portion 41A as indicated by a stream line L1. Peeled off from However, thereafter, the air that has reached the rear undercover 10 flows along the bottom surface 11 (having a downwardly curved surface) of the rear undercover 10 due to the Coanda effect described above.

  As described above, in the vehicle lower structure according to the present embodiment, even when the cover under the rear suspension member is omitted, it is possible to suppress a reduction in the rectifying effect of the rear under cover behind the rear suspension member.

Reference Signs List 10 rear under cover, 11 bottom surface of rear under cover, 20 battery pack, 30 rear suspension member, 40 battery under cover, 50 bumper reinforce, 60 rear bumper guard, 70 rear wheel, 80 lower arm, 85 rear side member.

Claims (1)

A battery pack installed under the floor panel,
A rear suspension member provided rearward in the vehicle length direction of the battery pack and supporting a rear wheel suspension mechanism;
A rear bumper guard provided at the rear end of the vehicle,
A battery undercover that covers a bottom surface of the battery pack;
A rear undercover extending from a lower rear portion of the rear suspension member to a lower end of the rear bumper guard;
A vehicle lower structure comprising:
A rear end of the battery under cover and a front end of the rear under cover are separated, and the rear suspension member is exposed to a road surface in a separation area thereof,
The bottom surface of the rear under cover facing the road surface is a curved surface that is convex downward.
Vehicle lower structure.

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