Vehicle understructure

Abstract

By directing the airflow under the floor undercover downwards from the rear suspension system, air resistance is reduced not only from the airflow escaping to the sides of the vehicle but also from being swirled around the rear wheels and their suspension system. [Solution] A vertical wall portion 33 is formed in the floor under cover 13 at the inner side in the vehicle width direction, adjacent to the deflector 21, with the rear side lowered to guide the airflow on the underside of the floor under cover 13 downward. The vertical wall portion 33 consists of an inner vertical wall portion 33a on the inner side in the vehicle width direction and an outer vertical wall portion 33b on the outer side in the vehicle width direction. The inclination of the inner vertical wall portion 33a with respect to the horizontal is gentler than that of the outer vertical wall portion 33b, and the fast airflow generated in the inner vertical wall portion 33a draws in the airflow passing through the outer vertical wall portion 33b, suppressing turbulence around the rear wheels 12.

Description

Technical Field

[0001] This invention relates to a vehicle's underbody structure considering aerodynamic performance.

Background Art

[0002] In vehicles, improvement of aerodynamic performance is required from the viewpoints of fuel efficiency, driving stability, comfort, etc. In the lower part of the vehicle, that is, under the floor, a smooth structure is adopted to reduce the air resistance in the front-rear direction.

[0003] In front of the rear wheels under the floor, since the driving wind hitting the rear wheels increases air resistance, a deflector is generally provided to reduce this. The deflector is for blocking the driving wind, and is formed in a plate shape that spreads in the vehicle width direction in front of the rear wheels and hangs downward, and is fixed to the floor frame. Since this deflector deflects the flow of the driving wind, the influence of disturbance can be weakened compared to the case where the flow directly hits the rear wheels.

[0004] Patent Document 1 below discloses a floor under cover having a deflecting surface portion that directs the driving wind to the front surface of the deflector. That is, on the outer surface in the vehicle width direction of the deflector in the floor under cover, which is inside the vehicle width direction of the deflector and in front of the deflector, a deflecting surface portion inclined toward the inner end in the vehicle width direction of the deflector is formed. By the deflecting surface portion directing the driving wind outward in the vehicle width direction, the driving wind received by the deflector is guided outward in the vehicle width direction, so that the aerodynamic performance can be maintained even if the outer end in the vehicle width direction of the deflector is located inward in the vehicle width direction from the outer end in the vehicle width direction of the rear wheel.

[0005] However, since the deflecting surface portion guides the driving wind outward in the vehicle width direction, there is a possibility that the driving wind guided in front of the deflector flows out to the side surface of the vehicle and has a negative impact on the aerodynamic performance. In addition, the deflecting surface portion not only directs the driving wind outward in the vehicle width direction, but also cannot be formed vertically or vertically long in the vertical direction, so there was a considerable amount of flow that was卷入 around the suspension device beyond the deflecting surface portion. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 7451933 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, the main objective of this invention is to reduce air resistance by directing the airflow under the floor under cover downwards, thereby suppressing not only the airflow that exits to the sides of the vehicle but also the turbulence around the rear wheels and their suspension system. [Means for solving the problem]

[0008] The vehicle's understructure for achieving this objective has the following configuration: In a vehicle understructure where a deflector is provided in front of the rear wheels beneath the vehicle's floor, a vertical wall section is formed in the area of ​​the floor under cover that is aligned with the deflector and on the inside in the vehicle width direction, with the rear side lowered to guide the airflow flowing on the underside of the floor under cover downwards. The vertical wall section is composed of an inner vertical wall section on the inside in the vehicle width direction and an outer vertical wall section on the outside in the vehicle width direction, with the inclination of the inner vertical wall section relative to the horizontal being gentler than that of the outer vertical wall section.

[0009] In this configuration, the inclination of the inner vertical wall creates a fast downward flow, attracting the flow adjacent to the outer vertical wall and directing the airflow under the floor under cover downward and inward in the vehicle width direction. At this time, a gentler inclination of the inner vertical wall reduces energy loss.

[0010] The aforementioned inner vertical wall section should be formed in a position corresponding to the trailing arm that extends forward from the support member of the suspension system supporting the rear wheels and connects to the vehicle body. Even in the movable range of the suspension system, which is difficult to cover with a cover, it becomes possible to efficiently cover it by incorporating a configuration that directs the airflow downwards.

[0011] When forming the inner vertical wall portion in a position corresponding to the trailing arm, it is preferable to form the inner vertical wall portion in a position that covers the area below the base of the trailing arm, and to position the rear end of the inner vertical wall portion forward of the rear end of the outer vertical wall portion, thereby forming a curved recess behind the inner vertical wall portion that allows for the presence of the trailing arm. This allows for more efficient covering and suppression of airflow entering the area around the suspension system.

[0012] Regarding the inner vertical wall section described above, it is preferable to form it in a shape that narrows towards the bottom. This directs the flow passing through the inner vertical wall section downwards, thereby increasing the effect of attracting the flow that comes into contact with the outer vertical wall section. In this case, if the outer edge in the vehicle width direction is sloped inward towards the vehicle width direction towards the bottom, the direction of the flow can be further directed inward in the vehicle width direction.

[0013] For the inner vertical wall section described above, it is preferable to form a wall-like rib that protrudes from the wall surface at the outer end of the inner vertical wall section in the vehicle width direction. The wall-like rib restricts the flow in the inner vertical wall section, creating a smoother flow and enhancing the effect of attracting the flow in contact with the outer vertical wall section.

[0014] Regarding the outer longitudinal wall portion described above, it is preferable that the outer end in the vehicle width direction is located outside the inner end in the vehicle width direction of the rear wheel. In the vehicle width direction, the outer longitudinal wall portion overlaps with the rear wheel, which can suppress the airflow flowing on the inside of the rear wheel in the vehicle width direction from being drawn into the rear wheel and its suspension system.

[0015] For the outer vertical wall section described above, it is preferable to form a flow-straightening rib at the top that extends in the front-to-back direction and bulges downward. The flow-straightening rib will smooth the flow that comes into contact with the outer vertical wall section, making it easier for the flow passing through the inner vertical wall section to pull it in. At the same time, the corners of the floor under cover will be reinforced, thereby creating rigidity and ensuring the effectiveness of the vertical wall section.

[0016] The floor undercover mentioned above should ideally be made of non-woven fabric. This will help reduce weight.

[0017] Regarding the above-mentioned deflector, it is preferably provided with an inclination such that the outer side in the vehicle width direction is positioned forward. This can suppress the running wind from exiting to the side of the vehicle.

[0018] Regarding the above-mentioned floor under cover, an extension portion extending rearward is formed in a portion inside the vehicle width direction rather than the vertical wall portion, and the rear end edge of the extension portion is preferably close to the suspension under cover provided on the lower surface of the suspension device that supports the rear wheels. The extension portion actively suppresses the entrainment of the running wind around the suspension device.

Advantages of the Invention

[0019] According to this invention, a vertical wall portion for guiding the running wind downward is provided, and a configuration is adopted in which the vertical wall portion is divided into the inside and outside in the vehicle width direction to more effectively direct the running wind downward. Therefore, the flow exiting to the side of the vehicle and the flow entrained around the rear wheels and their suspension device can be reduced. As a result, the aerodynamic performance can be improved.

Brief Description of the Drawings

[0020] [Figure 1] Perspective view of the lower structure of the vehicle. [Figure 2] Bottom view of the lower structure of the vehicle. [Figure 3] Enlarged view of the main part in FIG. 2. [Figure 4] Front view of the main part when viewing the vertical wall portion and the deflector from the front to the rear of the vehicle. [Figure 5] Side view of the main part.

Mode for Carrying Out the Invention

[0021] One embodiment for carrying out this invention will be described below with reference to the drawings.

[0022] Figure 1 shows a perspective view of the vehicle's understructure 11, specifically the rear wheels 12 and their front portion, viewed from the lower left. The white arrows in the figure indicate the vehicle's orientation to facilitate understanding of the drawing, and the letters inside the arrows indicate the direction. "Fr" indicates the front, "Rr" indicates the rear, "L" indicates the left, and "R" indicates the right. The same applies to Figure 2, which is a bottom view of the vehicle's understructure 11. Therefore, in Figures 1 and 2, the left side indicates the front of the vehicle, and the right side indicates the rear of the vehicle.

[0023] The vehicle's understructure 11 is comprised of a pair of left and right floor undercovers 13 located below the floor panel of the vehicle body. The rear end corners 13a on the outer side in the vehicle width direction of the left and right floor undercovers 13 are identical in structure and are symmetrical in shape. In Figure 2, the center line CL is a line indicating the midpoint in the vehicle width direction of the vehicle body.

[0024] First, I will explain the general structure of the vehicle's undercarriage 11, and then I will explain the floor under cover 13.

[0025] The structure of the vehicle body's floor and the rearward portion is the same as that of existing models. As shown in Figure 3, which is an enlarged view of the main part of Figure 2, the floor portion has side sills 14 arranged on both sides in the vehicle width direction and extending in the longitudinal direction, a floor frame 15 arranged on the inside of the side sills 14 in the vehicle width direction and extending in the longitudinal direction, and floor panels (not shown) that form the inner surface of the floor frame 15 in the vehicle width direction. A floor under cover 13 is fixed to the underside of these. The portion rearward from the floor portion consists of a rear frame 16 extending from the floor frame 15, a rear cross member (not shown), a rear floor panel (not shown), etc., and a suspension system 17 that supports the rear wheels 12, i.e., a rear suspension, is provided.

[0026] In this example, the suspension system 17 consists of a trailing arm type suspension. Specifically, for example, it is a so-called E-type multi-link suspension, in which the rear end of the trailing arm 17c is connected to the inside in the vehicle width direction of the support member 17b that rotatably supports the hub 17a to which the rear wheel 12 is fixed. The front end of the trailing arm 17c, which extends in the longitudinal direction, is fixed to the fixing part 15a on the lower surface of the floor frame 15.

[0027] Multiple suspension undercovers 18 are provided on the underside of the suspension device 17. These suspension undercovers 18 are positioned beneath the complexly shaped suspension device 17 to create a smooth structure beneath the suspension device 17, and they serve to suppress the intrusion of airflow around the suspension device 17 and reduce air resistance.

[0028] The rear fender 19, which surrounds the upper part of the rear wheel 12, is located at the rear end of the side sill 14, and a deflector 21 is provided at the front lower end of the rear fender 19, in front of the rear wheel 12. The deflector 21 is a flat plate that hangs vertically downwards from the vehicle and is fixed via a bracket 22 to a position corresponding to the outer plate member 14b side of the pair of inner plate members 14a and outer plate members 14b that make up the side sill 14 (see Figure 4, which is a view of the main part from the front to the rear of the vehicle).

[0029] The width dimension of the deflector 21 in the vehicle width direction is narrower than the width dimension of the rear wheel 12, and the outer edge of the deflector 21 in the vehicle width direction is located inward from the outer edge of the rear wheel 12 in the vehicle width direction. The deflector 21 is oriented parallel to the vehicle width direction, but may also have an appropriate inclination with respect to the vehicle width direction. In this example, as shown in Figure 2, it is provided with an inclination that positions the outer edge in the vehicle width direction forward. The inclination angle α should be a few degrees to about 5 degrees with respect to the vehicle width direction, preferably 4 degrees.

[0030] Next, I will explain the floor under cover 13.

[0031] As described above, the floor under cover 13, which is fixed to the underside of the floor portion of the vehicle body, is a three-dimensional tray shape with an appropriate depth and is formed by molding synthetic resin or nonwoven fabric. Similar to the suspension under cover 18, a smooth surface 31 is formed on the underside, which has an appropriate inclined surface, curved surface, groove, etc., extending in the front-rear direction, in order to reduce air resistance by forming a smooth structure. In addition, flanges 32 are formed on the periphery of the floor under cover 13, except for the outer end in the vehicle width direction, to improve shape retention. The outer edge in the vehicle width direction of the floor under cover 13 without flanges 32 is the part that is fixed directly or indirectly to the underside of the inner plate member 14a of the side sill 14, as shown in Figures 3 and 4, and the contour line of the edge is straight.

[0032] The rear end corner 13a on the outer side in the vehicle width direction, including the outer edge in the vehicle width direction, is located on the inner side in the vehicle width direction of the deflector 21, as can be seen in Figures 2 and 4. A vertical wall portion 33 is formed in this portion, that is, in the portion of the floor under cover 13 that is aligned with the deflector 21 and on the inner side in the vehicle width direction, with the rear side lowered to guide the airflow flowing on the underside of the floor under cover 13 downwards. The area in which the vertical wall portion 33 is formed is from the vicinity of the trailing arm 17c to the entire outer side in the vehicle width direction.

[0033] The vertical wall section 33 is divided into two parts, an inner and an outer section, in the vehicle width direction. The inner section is the inner vertical wall section 33a, and the outer section is the outer vertical wall section 33b, and their inclination angles with respect to the horizontal are different. Specifically, the inclination of the inner vertical wall section 33a with respect to the horizontal is set to be gentler than the inclination of the outer vertical wall section 33b. If the inclination angle β of the inner vertical wall section 33a is too steep, energy loss will be large, so as shown in Figure 5, it is good to set it to, for example, 30 degrees or less, preferably slightly less than 20 degrees to 25 degrees or around 21 degrees. The inclination angle γ of the outer vertical wall section 33b varies depending on conditions such as the vertical depth of the floor under cover 13, the molding material, and the draft angle during molding, but it is formed to be approximately 65 to 75 degrees.

[0034] As mentioned above, the outer edge of the floor under cover 13 in the vehicle width direction is fixed to the inner plate member 14a of the side sill 14, so as shown in Figure 4, the outer edge of the outer vertical wall portion 33b in the vehicle width direction is located outside the inner edge of the rear wheel 12 in the vehicle width direction. Furthermore, since the outer edge of the outer vertical wall portion 33b in the vehicle width direction is close to the inner edge of the deflector 21 in the vehicle width direction, the outer vertical wall portion 33b and the deflector 21 have a high degree of functional unity. The outer vertical wall portion 33b is positioned slightly forward of the inner edge of the deflector 21 in the vehicle width direction in the longitudinal direction of the vehicle.

[0035] The boundary between the inner vertical wall portion 33a and the outer vertical wall portion 33b is set on the outside in the vehicle width direction of the trailing arm 17c. In other words, the inner vertical wall portion 33a is formed at a position corresponding to the trailing arm 17c.

[0036] Since the inclination angle of the inner vertical wall portion 33a is gentler than that of the outer vertical wall portion 33b, the lengths in the front-rear direction differ for vertical wall portions 33 of the same depth. For this reason, the inner vertical wall portion 33a and the outer vertical wall portion 33b are offset front-rear, so that the rear end position of the inner vertical wall portion 33a is positioned forward of the rear end position of the outer vertical wall portion 33b. As described above, the inner vertical wall portion 33a is formed in a position corresponding to the trailing arm 17c, so the inner vertical wall portion 33a is formed in a position that covers the lower part of the front end of the trailing arm 17c, and a curved recess 34 that allows the presence of the trailing arm 17c is formed behind the inner vertical wall portion 33a. In plan view, the curved recess 34 is U-shaped with one side (outer side in the vehicle width direction) slightly open.

[0037] Of the inner vertical wall portion 33a and outer vertical wall portion 33b arranged side by side, the outer edge of the inner vertical wall portion 33a in the vehicle width direction, that is, the edge on the outer vertical wall portion 33b side, slopes inward in the vehicle width direction as it goes down, so that the inner vertical wall portion 33a is formed to become narrower towards the bottom. Even though it becomes narrower towards the bottom, the lower end of the inner vertical wall portion 33a is open and not closed. Therefore, the plan view shape of the inner vertical wall portion 33a is roughly like a long, narrow right triangle with its smallest angle cut off parallel to the opposite side.

[0038] In addition to the shape of the inner vertical wall portion 33a, there is also a draft angle, so the outer vertical wall portion 33b is conversely wider towards the bottom. Furthermore, the partition wall 35 that extends forward from the inside in the vehicle width direction of the outer vertical wall portion 33b and forms the boundary with the inner vertical wall portion 33a is tilted so as to lean inward in the vehicle width direction.

[0039] Between the partition wall 35 and the inner vertical wall portion 33a, that is, at the outer end of the inner vertical wall portion 33a in the vehicle width direction, a wall-like rib 36 is formed in a straight line extending from end to end, rising from the wall surface of the inner vertical wall portion 33a. The height of the wall-like rib 36 is the same from the upper end to the lower end, but it may be varied.

[0040] The inner vertical wall section 33a, which has a gentle slope relative to the horizontal, is formed with a flat wall surface, while the outer vertical wall section 33b, which has a steep slope, has a stepped section 37 and a flow-straightening rib 38. Specifically, in the middle of the outer vertical wall section 33b in the vertical direction, a stepped section 37 is formed that protrudes forward on the upper side, and above this stepped section 37, a flow-straightening rib 38 is formed that extends in the front-rear direction and bulges downward.

[0041] An extension 39 extending to the rear is formed in the portion of the vehicle width direction that is inward from the vertical wall portion 33. The length of the extension 39 in the front-rear direction is such that its rear end edge 39a is close to the suspension under cover 18.

[0042] The flange 32 is integrally formed with the vertical wall portion 33 on the outer side in the vehicle width direction, including this extension 39.

[0043] From the viewpoint of weight reduction, the floor under cover 13 having the above configuration is more preferably made of nonwoven fabric. The nonwoven fabric is manufactured by compression molding. The nonwoven fabric used is, for example, made of synthetic resin fibers such as polyethylene terephthalate and heat-meltable binder fibers.

[0044] The functions and effects of the vehicle's understructure 11, as described above, are explained below.

[0045] The airflow under the floor under cover 13 flows smoothly towards the rear due to the smooth surface 31, and at the rear end corner 13a located in front of the rear wheels 12, the airflow is directed downward, and moreover, downward below the suspension system 17 of the rear wheels 12. That is, as shown by the filled arrows in Figure 1, the airflow on the inside in the vehicle width direction of the airflow towards the vertical wall 33 is smoothly guided downward by the inner vertical wall 33a, which has a gentler slope than the outer vertical wall 33b. Since the inner vertical wall 33a covers the front end of the trailing arm 17c, the airflow is guided downward below the suspension system 17.

[0046] The inner vertical wall portion 33a is narrower towards the bottom, and combined with the presence of a wall-like rib 36 at the outer end in the vehicle width direction, the airflow through the inner vertical wall portion 33a is constricted and its speed increases. Furthermore, since the lower part of the inner vertical wall portion 33a is biased inward in the vehicle width direction, it creates airflow at a position further inward in the vehicle width direction than the rear wheels 12.

[0047] The fast flow in the inner vertical wall 33a, as shown by the thick arrows in Figures 1 and 3, pulls the airflow through the outer vertical wall 33b inward in the vehicle width direction. On the other hand, the outer vertical wall 33b is positioned so that its outer end in the vehicle width direction is outside the inner end of the rear wheel 12 in the vehicle width direction, and is formed to overlap with the rear wheel 12 in the vehicle width direction. Therefore, the outer vertical wall 33b itself makes it less likely for the flow passing through the outer vertical wall 33b to hit the inner side of the rear wheel 12 in the vehicle width direction. Furthermore, the flow passing through the outer vertical wall 33b is straightened by the rectifying rib 38 and flows downward, and as described above, is pulled inward in the vehicle width direction, thus being guided more efficiently inward in the vehicle width direction.

[0048] Even if the airflow along the outer vertical wall 33b is drawn inward in the vehicle width direction, the rearward-shaped recess 34 of the inner vertical wall 33a minimizes the exposure of the trailing arm 17c, and the extension 39 extends close to the suspension under cover 18, suppressing the intrusion of airflow into the interior. As a result, it is possible to suppress airflow from being drawn into the wheel well as around the suspension system.

[0049] At the rear corner 13a of the floor under cover 13, the airflow under the vehicle is guided downwards and further directed inward along the width of the vehicle, while the deflector 21 blocks the airflow that would otherwise hit the rear wheels 12. At the same time, because it is positioned with an inclination that positions the outer side in the width of the vehicle forward, it actively suppresses the airflow under the vehicle from escaping to the side of the vehicle along the vertical wall 33.

[0050] In this way, the airflow passing over the rear corner 13a on the underside of the floor undercover 13 can be prevented from being swept around the rear wheels 12 and the suspension system 17. Furthermore, the airflow passing over the underside of the floor undercover 13 can also be prevented from flowing out to the sides of the vehicle. As a result, air resistance can be reduced and aerodynamic performance can be improved.

[0051] Moreover, the rear end corner 13a of the floor under cover 13 is configured to cover the front end of the trailing arm 17c of the suspension device 17 while also providing the aforementioned effect. In other words, even in the movable range portion of the suspension device 17, which is generally difficult to cover with a cover, it is possible to efficiently cover it while incorporating a configuration that directs the airflow downwards, thereby suppressing the intrusion of airflow around the suspension device 17.

[0052] Furthermore, although the floor under cover 13 is preferably manufactured from nonwoven fabric as described above, even in this case, rigidity can be provided to the rear end corner portion 13a of the floor under cover 13, resulting in high morphological stability. Specifically, the rear end corner portion 13a has a vertical wall portion 33 and a flange 32 with different shaped parts, and the outer vertical wall portion 33b has a stepped portion 37 and a flow-straightening rib 38, while the inner vertical wall portion 33a has a wall-like rib 36. As a result, these uneven three-dimensional shapes ensure that the shape is maintained even when weight reduction is achieved, and the desired function is reliably performed.

[0053] The above configuration is one embodiment for carrying out this invention, and this invention is not limited to the above configuration; other configurations can be adopted.

[0054] For example, the floor under cover 13 may not be composed of a pair of left and right members, but rather of a single member. In this case, vertical wall portions 33 are formed at the rear end corners on both the left and right sides. [Explanation of symbols]

[0055] 11…Understructure of the vehicle 12... Rear wheel 13... Floor under cover 17...Suspension device 17b...Support member 17c... Trailing arm 18... Suspension under cover 21... Deflector 33...Vertical wall part 33a...Inner vertical wall part 33b…Outer vertical wall part 34…Bay-shaped recess 36... Wall-like ribs 38... Flow straightening ribs 39...Extension part 39a...rear edge

Claims

1. A vehicle understructure in which a deflector is provided in front of the rear wheels beneath the vehicle floor, A vertical wall portion is formed in the part of the floor under cover that is aligned with the deflector and on the inside in the vehicle width direction, with the rear side lowered to guide the airflow flowing on the underside of the floor under cover downwards. The aforementioned vertical wall portion is composed of an inner vertical wall portion on the inside in the vehicle width direction and an outer vertical wall portion on the outside in the vehicle width direction. The inclination of the inner vertical wall portion with respect to the horizontal is gentler than that of the outer vertical wall portion. The undercarriage of the vehicle.

2. The aforementioned inner vertical wall portion is formed at a position corresponding to the trailing arm that extends forward from the suspension system supporting the rear wheel and is connected to the vehicle body. The undercarriage structure of the vehicle according to claim 1.

3. The inner vertical wall portion is formed in a position that covers the lower part of the front end of the trailing arm, The rear end position of the inner vertical wall portion is positioned forward of the rear end position of the outer vertical wall portion. A curved recess is formed behind the inner vertical wall portion to allow for the presence of the trailing arm. The undercarriage structure of the vehicle according to claim 2.

4. The aforementioned inner vertical wall portion is formed in a shape that becomes narrower towards the bottom. The undercarriage structure of a vehicle according to claim 1 or claim 2.

5. A wall-like rib is formed at the outer end of the inner vertical wall portion in the vehicle width direction, protruding from the wall surface. The undercarriage structure of a vehicle according to claim 1 or claim 2.

6. The outer end of the outer vertical wall portion in the vehicle width direction is located further out than the inner end of the rear wheel in the vehicle width direction. The undercarriage structure of a vehicle according to claim 1 or claim 2.

7. A flow-straightening rib is formed on the upper part of the outer vertical wall portion, extending in the front-rear direction and bulging downward. The undercarriage structure of a vehicle according to claim 1 or claim 2.

8. The aforementioned floor under cover is made of nonwoven fabric. The undercarriage structure of a vehicle according to claim 1 or claim 2.

9. The deflector is provided with an inclination such that the outer side in the vehicle width direction is positioned forward. The undercarriage structure of a vehicle according to claim 1 or claim 2.

10. An extension portion extending to the rear is formed in the portion of the floor under cover that is inward in the vehicle width direction from the vertical wall portion. The rear end edge of the extension is close to the suspension under cover provided on the underside of the suspension system that supports the rear wheel. The undercarriage structure of a vehicle according to claim 1 or claim 2.

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