Vehicle undercover

Abstract

To provide an undercover for a vehicle which can generate a down force with high area efficiency.SOLUTION: An undercover 10 for a vehicle covers at least a part of a bottom part of the vehicle. The undercover comprises: a plurality of horizontal first planes 11a extending in a vehicle width direction; a plurality of horizontal second planes 15a extending in the vehicle width direction at a position higher than the first planes 11a; a plurality of first inclined faces 13a which extend with increasing upward inclination as they go rearward from rear end parts of the first planes 11a, and which are connected to front end parts of the second planes 15a; and a plurality of second inclined faces 17a which extend with increasing upward inclination as they go frontward from front end parts of the first planes 11a, and which are connected to rear end parts of the second planes 15a. A surface shape pattern SP which is constituted of the first planes 11a, the first inclination faces 13a, the second planes 15 and the second inclination faces 17a, which are continuous in a vehicle fore-and-aft direction, are formed on lower faces 10a so as to be repeated in the vehicle fore-and-aft direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle undercover that covers at least a portion of the bottom of a vehicle, and more particularly to a vehicle undercover that generates downforce that presses tires against the ground with good area efficiency. [Background technology]

[0002] Vehicle undercovers (hereinafter simply referred to as "undercovers") that are attached to the vehicle body to cover the bottom of the vehicle have been known for some time to prevent road interference and collisions or intrusion of foreign objects into vehicle parts (such as the engine, suspension, muffler, etc.) located on the bottom of the vehicle.

[0003] Such undercovers not only prevent interference with the road surface and collisions and intrusions of foreign objects, but also have the function of reducing air resistance by rectifying the air flowing under the vehicle (driving wind) by covering the unevenness on the bottom of the vehicle caused by vehicle parts. Recently, various proposals have been made regarding the shape of the undercover to enhance this air resistance reduction function.

[0004] For example, Patent Document 1 discloses an undercover in which concave portions recessed upward from the underside and convex portions protruding downward are alternately formed on the underside of the undercover along the longitudinal direction of the vehicle, the width of each concave portion in the vehicle width direction is set to be approximately the same, and the ridge lines between the concave portions are formed at an angle relative to the longitudinal direction of the vehicle.

[0005] According to Patent Document 1, small turbulences generated inside the recesses of the continuously curved recesses and protrusions create a turbulent layer across the entire underside of the undercover, and this turbulent layer causes the entire air flow to move away from the underside of the undercover, thereby reducing resistance near the underside of the undercover and suppressing the air resistance of the vehicle. Patent Document 1 also states that the air flow velocity increases as it moves away from the underside of the undercover. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-056573 Summary of the Invention [Problem to be solved by the invention]

[0007] It is known that when driving at high speeds, the turbulent layer disrupts the air flow near the undercover, causing the vehicle to wobble and resulting in an unstable ride with a weak sense of contact with the ground. To resolve this decline in the tire's road-following ability and ensure tire grip, thereby improving handling stability, it is effective to press the tire against the ground with an appropriate amount of downforce.

[0008] To efficiently generate downforce, it is conceivable to provide aero parts such as wings, spoilers, diffusers, etc., but these must be compatible with the exterior design and do not offer much freedom in design.In this regard, undercovers offer a high degree of freedom in design, and as mentioned above, they also have the function of rectifying the air flowing under the vehicle, so it is possible to generate downforce using undercovers as well.

[0009] More specifically, when the air flowing near the underside of the undercover increases in speed due to the undercover's air straightening function, according to Bernoulli's theorem (the sum of the energy of a fluid's position, velocity, and pressure is always constant), the pressure near the underside of the undercover decreases (negative pressure is generated), which can generate downforce.

[0010] However, not all vehicles can have an undercover covering a wide area of ​​the bottom, and for many vehicles the area on which an undercover can be installed is limited due to its position relative to the vehicle parts. The smaller the area on which an undercover can be installed, the more a vehicle requires an undercover structure that can generate downforce with greater area efficiency.

[0011] However, with a horizontal undercover that simply covers the unevenness of the bottom of the vehicle, the only thing that can be expected is an increase in air flow velocity through straightening, and the effect of increasing the speed of the air flowing near the underside of the undercover may be insufficient.If the area on which the undercover can be installed is limited, there is a problem that a sufficient downforce effect cannot be obtained.

[0012] Furthermore, in the case of Patent Document 1, the turbulent layer causes the air flow to move away from the underside of the undercover, but even if the flow velocity of the air leaving the underside of the undercover increases, this does not necessarily lead to the generation of negative pressure near the underside of the undercover, so there is still the problem that a sufficient downforce effect cannot be obtained.

[0013] The present invention has been made in consideration of these points, and its purpose is to provide a technology for realizing a vehicle undercover that is capable of generating downforce with high area efficiency. [Means for solving the problem]

[0014] In order to achieve the above-mentioned object, the vehicle undercover of the present invention directs air along a composite surface formed on the underside of the undercover, which is a combination of flat and inclined surfaces, thereby increasing the speed of air flowing near the underside of the undercover and causing separation and reattachment of air at the corners between the flat and inclined surfaces, thereby promoting the generation of vortices that generate negative pressure.

[0015] Specifically, the present invention provides: Has a wheelhouse Bottom of the vehicle Department This is intended for vehicle undercovers that cover the vehicle.

[0016] The vehicle undercover includes a first undercover extending in the vehicle width direction, and a second undercover located rearward of the first undercover and extending in the vehicle width direction, each of the first undercover and the second undercover having a first plane extending horizontally in the vehicle width direction, a first inclined surface extending from a rear end of the first plane at an upward inclination toward the rear, and a second inclined surface extending from a front end of the first plane at an upward inclination toward the front to the same height as the first inclined surface, and a surface shape pattern including at least a surface shape formed by the second inclined surfaces, the first planes, and the first inclined surfaces, which are continuous in the vehicle longitudinal direction, is formed on the underside so as to be repeated in the vehicle longitudinal direction. The surface shape pattern formed on each of the undercovers extends in the vehicle width direction and is located at a position overlapping the wheelhouse in the vehicle longitudinal direction. The vehicle further includes a horizontal second plane extending in the vehicle width direction at a position higher than the first plane, connecting a rear end of each of the first inclined surfaces with a front end of each of the second inclined surfaces located one surface behind the first inclined surfaces, and each of the surface shape patterns is made up of the first plane, the first inclined surfaces, the second plane, and the second inclined surfaces, which are continuous in the vehicle front-rear direction. It is characterized by the following.

[0017] In this configuration, a surface shape pattern including at least a surface shape in which the second inclined surface, the first plane surface, and the first inclined surface are combined in this order is repeatedly formed in the fore-and-aft direction of the vehicle on the underside of the undercover.

[0018] By forming such a surface shape pattern, the air flowing near the underside of the undercover (wind from driving) tends to flow along the second inclined surface, the first flat surface, and the first inclined surface due to the so-called Coanda effect. Therefore, by bending the air flow from the second inclined surface to the first flat surface, the first flat surface to the first inclined surface, and so on, the air speed increases, which makes it possible to reduce pressure (generate negative pressure) near the undercover's underside.

[0019] Furthermore, air flowing diagonally downward along the second inclined surface, which slopes upward toward the front (in other words, slopes downward toward the rear), continues to flow diagonally downward at the corner between the second inclined surface and the first flat surface, separating from the undercover, then immediately reattaching to the undercover and flowing along the horizontal first flat surface. This separation and reattachment generates a vortex with its axis in the vehicle width direction at the corner between the second inclined surface and the first flat surface. Similarly, air flowing rearward along the first flat surface continues to flow rearward at the corner between the first flat surface and the first inclined surface, separating from the undercover, then immediately reattaching to the undercover and flowing along the upward inclined first flat surface. This separation and reattachment also generates a vortex with its axis in the vehicle width direction at the corner between the first flat surface and the first inclined surface. Since the surface shape pattern is repeated in the fore-and-aft direction of the vehicle, the generation of multiple such vortices can generate a relatively large negative pressure near the undercover's underside.

[0020] As described above, by forming the above-described surface shape pattern in the vehicle undercover of the present invention, negative pressure can be generated near the underside of the undercover by increasing the speed of the wind while the vehicle is running, and negative pressure can also be generated near the underside of the undercover by generating vortices, which together enable downforce to be generated with good area efficiency. Therefore, even if the area on which the undercover can be installed is limited, it is possible to press the tire against the ground with an appropriate amount of downforce, thereby improving handling stability.

[0022] In this configuration, a surface shape pattern that combines, in this order, a relatively low horizontal first plane, an upwardly sloping first inclined surface, a relatively high horizontal second plane, and a downwardly sloping second inclined surface is repeatedly formed in the fore-and-aft direction of the vehicle on the underside of the undercover.

[0023] By forming such a surface shape pattern, the air flowing near the underside of the undercover tends to flow along the first plane, first inclined plane, second plane, and second inclined plane due to the Coanda effect. Therefore, by bending the air flow from the first plane to the first inclined plane, the first inclined plane to the second plane, the second plane to the second inclined plane, the second inclined plane to the first plane, and so on, the air speed increases, which makes it possible to generate negative pressure near the underside of the undercover.

[0024] Similarly to the above, vortices with axes in the vehicle width direction are generated at the corners between the second inclined surface and the first flat surface, and at the corners between the first flat surface and the first inclined surface. Since the surface shape pattern is repeated in the fore-and-aft direction of the vehicle, the generation of multiple such vortices can generate a relatively large negative pressure near the underside of the undercover.

[0025] These features work together to generate downforce with high area efficiency, which means that even if the area in which the undercover can be installed is limited, it is possible to press the tires against the ground with moderate downforce, thereby improving handling stability.

[0026] Furthermore, in the vehicle undercover, the angle formed between the second inclined surface and the first plane may be set to be equal to or greater than the angle formed between the first inclined surface and the first plane.

[0027] Because the air flowing rearward hits the second inclined surface, if the angle of the second inclined surface (= the angle between the second inclined surface and the first plane) is close to a right angle, a large negative pressure can be generated, but this will hinder acceleration. On the other hand, if the angle of the second inclined surface is close to 0, neither a large negative pressure nor a significant acceleration can be expected. Therefore, it is preferable that the angle between the second inclined surface and the first plane is relatively large, as long as it does not hinder acceleration.

[0028] In this way, when the angle between the second inclined surface and the first plane is increased, the accelerated air flowing diagonally downward along the second inclined surface continues to flow diagonally downward from the corner between the second inclined surface and the first plane, and becomes detached from the undercover. However, due to the influence of the wind originally flowing rearward, it is easy for the detached air to reattach to the first plane, which extends in the same direction as the flow of the wind, and therefore the generation of vortices is not hindered.

[0029] On the other hand, if the angle between the first inclined surface and the first plane is made too large, the accelerated air flowing rearward along the first plane will continue to flow rearward from the corner between the first plane and the first inclined surface and become detached from the undercover. However, because the traveling wind is originally flowing rearward, it is not easy to make the detached air reattach to the first inclined surface, which extends in a different direction from the flow of the traveling wind.

[0030] In this regard, with this configuration, the angle formed between the second inclined surface and the first plane is set to be equal to or greater than the angle formed between the first inclined surface and the first plane, so the angle formed between the second inclined surface and the first plane becomes relatively large, while the angle formed between the first inclined surface and the first plane becomes relatively small. In this way, the relatively large angle formed between the second inclined surface and the first plane makes it possible to generate a relatively large negative pressure near the underside of the undercover, and the relatively small angle formed between the first inclined surface and the first plane promotes separation and reattachment of air, thereby reliably generating vortices, thereby making it possible to generate downforce with greater area efficiency.

[0031] Furthermore, since it is sufficient that the angle between the second inclined surface and the first plane is equal to or greater than the angle between the first inclined surface and the first plane, it is also possible for the angle between the second inclined surface and the first plane to be equal to the angle between the first inclined surface and the first plane to generate a relatively large negative pressure, and the angle between the first inclined surface and the first plane to generate a vortex.However, in order to reliably generate a relatively large negative pressure and vortex, it is preferable that the angle between the second inclined surface and the first plane be set to be greater than the angle between the first inclined surface and the first plane.

[0032] In the present invention, the surface shape pattern formed on the underside of the undercover, which is repeated in the fore-and-aft direction of the vehicle, repeatedly increases the air speed and generates vortices, thereby generating a relatively large negative pressure near the underside of the undercover.However, if the air flowing rearward spreads too far in the vehicle width direction, the air flow will be disrupted and these effects may be reduced.

[0033] Therefore, the vehicle undercover may further include vertical wall portions extending downward from each of the second planes and the first and second inclined surfaces adjacent to the front and rear of each of the second planes, and the vertical wall portions may be arranged in a row in the fore-and-aft direction of the vehicle.

[0034] According to this configuration, the space extending in the vehicle width direction, which is defined by the virtual plane at the same height as the first plane, the second plane, and the first and second inclined surfaces, is partitioned in the vehicle width direction by the vertical wall portions extending downward from the second plane and the first and second inclined surfaces. Since these vertical wall portions are not provided at random positions in the vehicle width direction but are provided in a row in the vehicle front-rear direction, the surface shape pattern is repeated in the vehicle front-rear direction, and the areas partitioned in the vehicle width direction by the vertical wall portions are lined up in multiple rows in the vehicle width direction.

[0035] In this way, by dividing the area in the vehicle undercover through which air flows into multiple rows of regions aligned in the vehicle width direction, the air flows without spreading too far in the vehicle width direction in each region, which promotes streamlining and thereby enables downforce to be generated with even greater area efficiency. [Effects of the Invention]

[0036] As described above, the vehicle undercover according to the present invention can generate downforce with good area efficiency. [Brief explanation of the drawings]

[0037] [Figure 1]1A and 1B are diagrams showing a vehicle equipped with a vehicle undercover according to a first embodiment of the present invention, in which FIG. 1A is a side view and FIG. 1B is a bottom view. [Figure 2] FIG. 3 is a plan view schematically showing a surface shape pattern formed on the lower surface of the vehicle undercover. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 1 is a diagram for schematically explaining the action and effect of a surface shape pattern. [Figure 5] FIG. 1 is a diagram for schematically explaining the mechanism of increasing the velocity of air. [Figure 6] 5A and 5B are diagrams for explaining a method for determining angles formed between the first and second inclined surfaces and the first plane. [Figure 7] FIG. 10 is a plan view schematically showing a surface shape pattern formed on the lower surface of a vehicle undercover according to a second embodiment of the present invention. [Figure 8] 8A and 8B are diagrams schematically showing a surface shape pattern, where FIG. 8A is a cross-sectional view taken along line VIIIa-VIIIa in FIG. 7, and FIG. 8B is a cross-sectional view taken along line VIIIb-VIIIb in FIG. [Figure 9] FIG. 10 is a diagram for explaining the action and effect of the vertical wall portion. [Figure 10] FIG. 10 is a cross-sectional view that schematically shows a surface shape pattern formed on the lower surface of a vehicle undercover according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, arrow Fw indicates the front side in the longitudinal direction of the vehicle, arrow Rh indicates the right side in the width direction of the vehicle, arrow Lf indicates the left side in the width direction of the vehicle, and arrow Up indicates the up side in the vertical direction.

[0039] (Embodiment 1) 1A and 1B are diagrams schematically illustrating a vehicle 1 equipped with a vehicle undercover 10 according to this embodiment, with FIG. 1A being a side view and FIG. 1B being a bottom view. Note that the number and mounting positions of the vehicle undercovers 10 (hereinafter simply referred to as "undercovers 10") in FIG. 1B are merely examples and are not particularly limited.

[0040] As shown in Fig. 1(b), this vehicle 1 is equipped with five resin undercovers 10A, 10B, 10C, 10D, and 10E attached to the front, center, and rear ends in the longitudinal direction of the vehicle so as to cover vehicle components (not shown) provided on the bottom of the vehicle. These undercovers 10A to 10E not only prevent the vehicle components from interfering with the road surface and from being hit or intruded by foreign objects, but also have the function of reducing air resistance by covering the unevenness of the vehicle components and rectifying the air flowing under the vehicle 1 (driving wind) as indicated by the thick arrows in Fig. 1(a).

[0041] In addition, the undercover 10 also has the function of generating downforce that presses the tires 3, 5 against the ground, as shown by the black arrows in Figure 1(a). However, in this vehicle 1, the area in which the undercover 10 can be attached is limited due to its position relative to the vehicle parts, as shown in Figure 1(b), so an undercover structure that can generate downforce with efficient area utilization is required.

[0042] Hereinafter, the vehicle undercover 10 according to this embodiment, which is capable of generating downforce with good area efficiency even when the area in which the undercover 10 can be attached is small, will be described in detail.

[0043] -Surface shape pattern- Fig. 2 is a plan view schematically showing the surface shape pattern SP formed on the underside 10a of the vehicle undercover 10, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. On the underside 10a of the undercover 10, the surface shape pattern SP as shown in Figs. 2 and 3 is formed so as to be repeated in the longitudinal direction of the vehicle. Each surface shape pattern SP is made up of the underside 11a of the first flat surface portion 11, the underside 13a of the first inclined surface portion 13, the underside 15a of the second flat surface portion 15, and the underside 17a of the second inclined surface portion 17.

[0044] In relation to the claims, the lower surface 11a of the first flat surface portion 11 corresponds to the "first plane" as defined in the present invention, the lower surface 13a of the first inclined surface portion 13 corresponds to the "first inclined surface" as defined in the present invention, the lower surface 15a of the second flat surface portion 15 corresponds to the "second flat surface" as defined in the present invention, and the lower surface 17a of the second inclined surface portion 17 corresponds to the "second inclined surface" as defined in the present invention.

[0045] Therefore, for convenience, in the following, the lower surface 11a of the first flat surface portion 11 will also be referred to as the "first flat surface 11a," the lower surface 13a of the first inclined surface portion 13 will also be referred to as the "first inclined surface 13a," the lower surface 15a of the second flat surface portion 15 will also be referred to as the "second flat surface 15a," and the lower surface 17a of the second inclined surface portion 17 will also be referred to as the "second inclined surface 17a."

[0046] The first flat surface 11 extends in the vehicle width direction, and its lower surface 11a is formed as a horizontal surface extending in the vehicle width direction, as shown in Fig. 2. On the other hand, the second flat surface 15 extends in the vehicle width direction at a position higher than the first flat surface 11, and its lower surface 15a is formed as a horizontal surface extending in the vehicle width direction at a position higher than the lower surface 11a, as shown in Fig. 3. These first flat surface portions 11 and second flat surface portions 15 are provided in plurality and arranged alternately at intervals in the vehicle fore-and-aft direction, and are connected by the first and second inclined surface portions 13, 17.

[0047] 3, the first inclined surface portion 13 extends from the rear end of the first flat surface portion 11 so as to slope upward as it extends rearward, and is connected to the front end of the second flat surface portion 15 located one plane rearward of the first flat surface portion 11. On the other hand, the second inclined surface portion 17 extends from the rear end of the second flat surface portion 15 so as to slope downward as it extends rearward, and is connected to the front end of the first flat surface portion 11 located one plane rearward of the second flat surface portion 15. The inclination angles of the first inclined surface portion 13 and the second inclined surface portion 17 (angles θ1 and θ2 formed between the first inclined surface 13a and the first flat surface 11a and between the second inclined surface 17a and the first flat surface 11a) will be described later.

[0048] In this way, in the undercover 10, a relatively low horizontal first plane 11a, an upwardly sloping first inclined surface 13a, a relatively high horizontal second plane 15a, and a downwardly sloping second inclined surface 17a are combined in this order to form a surface shape pattern SP that is repeated in the fore-and-aft direction of the vehicle.

[0049] In the undercover 10 of this embodiment, the lower surface 11a of the first flat surface 11 is formed at the same height as the lower surface (hereinafter also referred to as the "general surface") of the flat surface (not shown) that has the largest area ratio in the undercover 10. Therefore, in the surface shape pattern SP of this embodiment, a groove portion is formed that is recessed upward from the general surface and is defined by the first inclined surface 13a, the second flat surface 15a, and the second inclined surface 17a.

[0050] -Actions and effects of surface shape patterns- FIG. 4 is a diagram illustrating the action and effect of the surface shape pattern SP. By forming the surface shape pattern SP as described above, air (traveling wind) flowing near the underside 10a of the undercover 10 tends to flow along the first flat surface 11a, the first inclined surface 13a, the second flat surface 15a, and the second inclined surface 17a due to the so-called Coanda effect, which is a phenomenon in which a fluid behaves as if it is in continuous contact with a convex wall surface. Therefore, the air flow is bent from the first flat surface 11a to the first inclined surface 13a, from the first inclined surface 13a to the second flat surface 15a, from the second flat surface 15a to the second inclined surface 17a, and from the second inclined surface 17a to the first flat surface 11a, etc., thereby increasing the speed of the air flowing near the underside 10a of the undercover 10. As a result, the flow velocity of the air flowing near the underside 10a of the undercover 10 is faster downstream (see DS in FIG. 4 ) than upstream (see US in FIG. 4 ).

[0051] Here, we will briefly explain the mechanism by which the speed of air increases when the air flow is bent. Figure 5 is a diagram that schematically explains the mechanism by which the speed of air increases. In Figure 5, air is replaced with water W to make the explanation easier to understand. In the following, for the sake of simplicity, the explanation will be given ignoring changes in potential energy, speed increases due to gravitational acceleration, and friction between plates 30, 31, and 32.

[0052] As shown in Figure 5(a), assume that water W flows at a constant flow rate from faucet 40. If the flow velocity of water W at position A in Figure 5 is V, then the flow velocity of water W at position B, which is a length L below position A, also remains V.

[0053] Thus, as shown in Figure 5(b), even if water W is made to flow along the surface 30a of a plate 30 having a length L and no irregularities in the AB section, if the flow velocity of water W at position A is V, then naturally the flow velocity of water W at position B will also remain V.

[0054] On the other hand, as shown in Figure 5(c), assume that water W is made to flow along the surface 31a of the bent plate 31 in the section AB. In this case, if the flow velocity of water W at position A is V, then naturally the flow velocity of water W at position B will also remain V. However, the flow path length of the surface 31a of the bent plate 31 is longer than the length L. If this is the case, then the flow velocity V' of water W in the section AB must be faster than V for this to make sense. In other words, the flow velocity of water W is transiently increased by flowing through the bent section.

[0055] However, as shown in Figure 5(d), if water W is made to flow along the surface 32a of the plate 32 having the baffle plate 32b, the water W will splash (or, in the case of air, it will peel off), and no transient increase in speed will occur as shown in Figure 5(c).

[0056] The above also applies to air; if the air flow is bent while maintaining contact with the surface shape pattern SP due to the Coanda effect without separating from the undercover 10 (excluding temporary separation and reattachment), the air speed will be increased transiently (while it is in contact with the surface shape pattern SP).

[0057] In this way, with the undercover 10 of this embodiment, the air flow is intentionally bent, thereby increasing the speed of the air flowing along the underside 10a of the undercover 10, thereby reducing the pressure (generating negative pressure) near the underside 10a of the undercover 10. Since the surface shape pattern SP is repeated in the fore-and-aft direction of the vehicle, this increase in the speed of the air is repeated, making it possible to continuously (sustainably) generate negative pressure near the underside 10a of the undercover 10.

[0058] Furthermore, as shown by the hollow arrow in Figure 4, the air flowing diagonally downward along the downwardly sloping second inclined surface 17a continues to flow diagonally downward and separates from undercover 10 at corner 14 between second inclined surface 17a and first plane 11a, and then immediately reattaches to undercover 10 and flows along the relatively low, horizontal first plane 11a. Due to this separation and reattachment, a vortex with its axis in the vehicle width direction is generated at corner 14 between second inclined surface 17a and first plane 11a, as shown by the thick arrow V1 in Figure 4.

[0059] Similarly, as shown by the hatched arrows in Fig. 4, the air flowing rearward along the first flat surface 11a continues to flow rearward and separates from the undercover 10 at the corner 16 between the first flat surface 11a and the first inclined surface 13a, then immediately reattaches to the undercover 10 and flows along the upwardly inclined first inclined surface 13a, and this separation and reattachment also generates a vortex with its axis in the vehicle width direction at the corner 16 between the first flat surface 11a and the first inclined surface 13a, as shown by the thick arrow V2 in Fig. 4. Since the surface shape pattern SP is repeated in the fore-and-aft direction of the vehicle, the generation of multiple such vortices makes it possible to generate a relatively large negative pressure near the undersurface 10a of the undercover 10.

[0060] As described above, by forming the surface shape pattern SP in the vehicle undercover 10 of this embodiment, negative pressure can be generated near the underside 10a of the undercover 10 by increasing the speed of the traveling wind, and negative pressure can be generated near the underside 10a of the undercover 10 by generating vortices, and these together can generate downforce with good area efficiency. Therefore, even if the area in which the undercover 10 can be attached is limited, it is possible to press the tires 3, 5 against the ground with an appropriate downforce, thereby improving handling stability.

[0061] -Inclination angle of the first and second inclined planes- In the vehicle undercover 10 of this embodiment, the angle θ2 formed between the second inclined surface 17a and the first plane 11a is set to be larger than the angle θ1 formed between the first inclined surface 13a and the first plane 11a. The reason for setting the relationship between the angles θ1 and θ2 in this manner will be explained below.

[0062] 6A and 6B are diagrams illustrating a method for determining the angles θ1 and θ2 formed between the first and second inclined surfaces 13a and 17a and the first plane 11a. First, as shown in FIG. 6A, when an aero part 120 is provided hanging down from the undercover 110, a large negative pressure can be generated near the back surface of the aero part 120 (see the hatched area in FIG. 6A). However, this inhibits the increase in air velocity near the undersurface of the undercover 110. Therefore, since the air flowing along the second plane 15a hits the second inclined surface 17a, if the angle formed between the second plane 15a and the second inclined surface 17a (= the angle θ2 formed between the second inclined surface 17a and the first plane 11a) is close to a right angle, a large negative pressure can be generated, but the increase in air velocity will be inhibited.

[0063] On the other hand, as shown in Figure 6(b), in the case of a horizontal undercover 210 in which the angle (= θ2) between the second plane 15a and the second inclined surface 17a is 0, a significant increase in speed or generation of negative pressure cannot be expected for the same reasons as in the case of Figure 5(b).

[0064] For these reasons, it is preferable that the angle formed between the second plane 15a and the second inclined surface 17a (= the angle θ2 formed between the second inclined surface 17a and the first plane 11a) be relatively large within a range that does not hinder acceleration, and it is preferable to set it to, for example, about 45°.

[0065] In this way, when the angle θ2 between the second inclined surface 17a and the first plane 11a is increased, the accelerated air flowing diagonally downward along the second inclined surface 17a continues to flow diagonally downward from the corner 14 between the second inclined surface 17a and the first plane 11a, as shown by the dashed arrow in Figure 6(c), and separates from the undercover 10. However, due to the influence of the wind originally flowing rearward, it is easy for the air that has once separated to reattach to the first plane 11a, which extends in the same direction as the flow of the wind, and therefore the generation of a vortex is not hindered.

[0066] In contrast, as shown in Figure 6(d), if the angle θ1 between the first inclined surface 13a and the first plane 11a is made too large, the accelerated air flowing rearward along the first plane 11a will continue to flow rearward from the corner 16 between the first plane 11a and the first inclined surface 13a, as shown by the dashed arrow in Figure 6(d), and will be separated from the undercover 10. However, because the traveling wind is originally flowing rearward, it is not easy to make the air that has once separated rearward reattach to the first inclined surface 13a, which extends in a direction different from the flow of the traveling wind.

[0067] Therefore, it is preferable that the angle θ1 between the first inclined surface 13a and the first plane 11a is small enough to allow air that has once separated from the corner 16 between the first plane 11a and the first inclined surface 13a to reattach to the first inclined surface 13a, as shown in Figure 6(e), and it is preferable to set it to, for example, about 27°.

[0068] As described above, in the vehicle undercover 10 of this embodiment, the angle θ2 formed between the second inclined surface 17a and the first flat surface 11a is set to be larger than the angle θ1 formed between the first inclined surface 13a and the first flat surface 11a, so the angle θ2 formed between the second inclined surface 17a and the first flat surface 11a is relatively large, while the angle θ1 formed between the first inclined surface 13a and the first flat surface 11a is relatively small. In this way, the relatively large angle θ2 formed between the second inclined surface 17a and the first flat surface 11a makes it possible to generate a relatively large negative pressure near the undersurface 10a of the undercover 10, and the relatively small angle θ1 formed between the first inclined surface 13a and the first flat surface 11a promotes separation and reattachment of air, thereby reliably generating vortices, thereby enabling downforce to be generated with greater area efficiency.

[0069] (Embodiment 2) This embodiment differs from the first embodiment in that a vertical wall portion is provided. The following description will focus on the differences from the first embodiment.

[0070] Fig. 7 is a plan view schematically showing the surface shape pattern SP formed on the underside 10a of the vehicle undercover 10 according to this embodiment, Fig. 8(a) is a cross-sectional view taken along line VIIIa-VIIIa in Fig. 7, and Fig. 8(b) is a cross-sectional view taken along line VIIIb-VIIIb in Fig. 7. Fig. 9 is a diagram schematically illustrating the action and effect of the vertical wall portion 20.

[0071] As explained in embodiment 1, in the undercover 10, the surface shape pattern SP that is repeated in the fore-and-aft direction of the vehicle repeatedly increases the air velocity and generates vortices, thereby generating a relatively large negative pressure near the undersurface 10a of the undercover 10. However, as shown by the thick arrows in Figure 9(a), if the air flowing rearward spreads too far in the vehicle width direction, the air flow will be disrupted and these effects may be reduced.

[0072] Therefore, in this embodiment, in order to divide the area in the vehicle undercover 10 where the air speed increases and vortexes are generated into areas where the air flow does not spread too much in the vehicle width direction, a vertical wall portion 20 is provided as shown in Figure 7.

[0073] As shown in FIG. 8, each vertical wall portion 20 has a pair of side wall portions 21 and a bottom wall portion 23. As shown in FIG. 8(a), the pair of side wall portions 21 extend downward from the second flat surface 15a and the first and second inclined surfaces 13a, 17a adjacent to the front and rear of the second flat surface 15a to the same height as the first flat surface 11a, and are formed in a trapezoidal shape when viewed in the vehicle width direction. The bottom wall portion 23 is at the same height as the first flat surface 11a and connects the lower ends of the pair of side wall portions 21 to each other. In other words, each vertical wall portion 20 is formed in a shape such that the second flat surface 15a and the first and second inclined surfaces 13a, 17a adjacent to the front and rear of the second flat surface 15a are recessed to the same height as the first flat surface 11a. The vertical wall portions 20 formed in this manner are not provided at random positions in the vehicle width direction, but are provided in a plurality of groove portions so as to form a row in the vehicle front-rear direction, as shown in FIG.

[0074] By providing such vertical wall portion 20, a space (groove portion) extending in the vehicle width direction, which is defined by a virtual plane (not shown) at the same height as first plane 11a, second plane 15a, and first and second inclined surfaces 13a, 17a, is partitioned in the width direction. Because vertical wall portion 20 thus serves to partition the groove portion formed by surface shape pattern SP in the width direction, it is preferable that angle θ3 between side wall portion 21 and bottom wall portion 23 be as close to a right angle as possible. In this embodiment, angle θ3 is set to, for example, 85°, taking into account the mold removal angle and other factors when injection molding resin undercover 10.

[0075] Since the vertical wall portions 20 are arranged in rows in the fore-and-aft direction of the vehicle, as shown in Figure 9(b), the surface shape pattern SP is repeated in the fore-and-aft direction of the vehicle, and the areas R partitioned in the vehicle width direction by the vertical wall portions 20 are arranged in multiple rows in the vehicle width direction.

[0076] In this way, by dividing the areas in the vehicle undercover 10 where the air speed increases and vortices are generated into multiple regions R lined up in the vehicle width direction, as shown by the thick arrows in Figure 9(b), the air flows in each region R without spreading too much in the vehicle width direction, which promotes streamlining and allows downforce to be generated with even greater area efficiency.

[0077] The optimum width of the region R is preferably set to 200 mm or less. In other words, if the length of the surface shape pattern SP in the vehicle width direction exceeds 200 mm, it is preferable to provide the vertical wall portion 20 to prevent the air flow from spreading too much in the vehicle width direction.

[0078] (Embodiment 3) This embodiment differs from the first embodiment in that it does not include the second flat portion 15. The following description will focus on the differences from the first embodiment.

[0079] Fig. 10 is a cross-sectional view schematically showing a surface shape pattern SP' formed on the underside 10a' of a vehicle undercover 10' according to this embodiment. On the underside 10a' of the undercover 10', the surface shape pattern SP' as shown in Fig. 10 is formed so as to be repeated in the front-to-rear direction of the vehicle. Each surface shape pattern SP' is made up of the underside 11a of the first flat surface portion 11, the underside 13a' of the first inclined surface portion 13', and the underside 17a' of the second inclined surface portion 17'.

[0080] For convenience, the lower surface 13a' of the first inclined surface portion 13' will also be referred to as the "first inclined surface 13a'", and the lower surface 17a' of the second inclined surface portion 17' will also be referred to as the "second inclined surface 17a'".

[0081] As shown in Fig. 10, the first inclined surface portion 13' extends from the rear end of the first flat surface portion 11 so as to be inclined upward as it extends rearward. On the other hand, the second inclined surface portion 17' extends from the front end of the first flat surface portion 11 so as to be inclined upward as it extends forward to the same height as the first inclined surface portion 13', and its front end is connected to the rear end of the first inclined surface portion 13'. The inclination angles of the first inclined surface portion 13' and the second inclined surface portion 17' (angles θ1 and θ2 formed between the first inclined surface 13a' and the first flat surface 11a and the second inclined surface 17a') are the same as those in the first embodiment.

[0082] In this way, in the undercover 10', a horizontal first plane 11a, an upwardly sloping first inclined surface 13a', and a downwardly sloping second inclined surface 17a' are combined in this order to form a surface shape pattern SP' that is repeated in the fore-and-aft direction of the vehicle.

[0083] By forming such a surface shape pattern SP', air flowing near the lower surface 10a' of the undercover 10' tends to flow along the second inclined surface 17a', the first flat surface 11a, and the first inclined surface 13a' due to the Coanda effect. Therefore, the air flow is bent in the following order: second inclined surface 17a' → first flat surface 11a, first flat surface 11a → first inclined surface 13a', first inclined surface 13a' → second inclined surface 17a', etc., and the speed of the air increases. As a result, negative pressure can be generated near the lower surface 10a' of the undercover 10', as in the first embodiment.

[0084] Furthermore, at a corner 14' between the second inclined surface 17a' and the first flat surface 11a, and at a corner 16' between the first flat surface 11a and the first inclined surface 13a', air separates and reattaches, generating vortices with their axes in the vehicle width direction at these corners 14', 16', just as in embodiment 1. Since the surface shape pattern SP' is repeated in the vehicle fore-and-aft direction, multiple such vortices are generated, which can generate a relatively large negative pressure near the underside 10a' of the undercover 10'.

[0085] (Other embodiments) The present invention is not limited to the embodiments, and can be implemented in various other forms without departing from the spirit or main characteristics thereof.

[0086] In the above-described embodiments, the angle θ2 between the second inclined surface 17a and the first flat surface 11a is set to be larger than the angle θ1 between the first inclined surface 13a and the first flat surface 11a. However, this is not limiting. For example, the angle θ2 between the second inclined surface 17a and the first flat surface 11a, which allows a relatively large negative pressure to be generated, may be the same as the angle θ1 between the first inclined surface 13a and the first flat surface 11a, which allows a vortex to be generated. In other words, the angle θ2 between the second inclined surface 17a and the first flat surface 11a may be set to be larger than the angle θ1 between the first inclined surface 13a and the first flat surface 11a.

[0087] In addition, in each of the above embodiments, the angle θ1 is set to 27°, the angle θ2 is set to 45°, the angle θ3 is set to 85°, and the optimal width of the region R is set to 200 mm or less, but these are merely examples and may be set to values ​​other than these without being limited to these.

[0088] In addition, in each of the above embodiments, the first flat surface 11a is formed at the same height as the general surface, but this is not limiting, and the second flat surface 15a may also be formed at the same height as the general surface. In this way, when the second flat surface 15a is formed at the same height as the general surface, a convex portion is formed that protrudes downward from the general surface and is defined by the second inclined surface 17a, the first flat surface 11a, and the first inclined surface 13a.

[0089] Furthermore, in the above-mentioned embodiment 2, a hollow vertical wall portion 20 is formed, but this is not limited to this, and for example, a solid vertical wall portion extending downward from the second plane 15a and the first and second inclined surfaces 13a, 17a may be formed.

[0090] As such, the above-described embodiments are merely examples in all respects and should not be interpreted as limiting. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0091] According to the present invention, downforce can be generated with high area efficiency, and therefore it is extremely useful when applied to a vehicle undercover that covers at least a portion of the bottom of the vehicle. [Explanation of symbols]

[0092] 1 vehicle 10,10' vehicle undercover 10a,10a' bottom surface 11a Lower surface of the first plane part (first plane) 13a, 13a' Lower surface of the first inclined surface (first inclined surface) 15a Bottom surface of the second plane part (second plane) 17a,17a' Lower surface of the second inclined surface (second inclined surface) 20 Vertical wall section SP, SP' surface shape pattern θ1 Angle between the first inclined surface and the first plane θ2 Angle between the second inclined plane and the first plane

Claims

1. A vehicle undercover that covers the bottom of a vehicle having a wheelhouse, a first undercover extending in the vehicle width direction; a second undercover disposed rearward of the first undercover and extending in the vehicle width direction, The first undercover and the second undercover are a horizontal first plane extending in the vehicle width direction; a first inclined surface extending from a rear end of the first plane to be inclined upward toward the rear; a second inclined surface inclined upward from the front end of the first plane toward the front and extending to the same height as the first inclined surface; Each has multiple a surface shape pattern including at least a surface shape formed by the second inclined surfaces, the first flat surfaces, and the first inclined surfaces, which are continuous in the vehicle longitudinal direction, is formed on the lower surface so as to be repeated in the vehicle longitudinal direction; the surface shape pattern formed on each undercover extends in the vehicle width direction and is disposed at a position overlapping with the wheel house in the vehicle front-rear direction, a horizontal second plane extending in the vehicle width direction at a position higher than the first plane, connecting a rear end of each of the first inclined surfaces to a front end of each of the second inclined surfaces located one surface rearward of each of the first inclined surfaces; a vehicle undercover characterized in that each of the surface shape patterns is composed of the first flat surfaces, the first inclined surfaces, the second flat surfaces, and the second inclined surfaces, which are continuous in the fore-and-aft direction of the vehicle.

2. In the vehicle undercover described in claim 1, The vehicle undercover is characterized in that the angle formed between the second inclined surface and the first plane is set to be equal to or larger than the angle formed between the first inclined surface and the first plane.

3. In the vehicle undercover described in claim 2, The vehicle undercover is characterized in that the angle formed between the second inclined surface and the first plane is set to be larger than the angle formed between the first inclined surface and the first plane.

4. In the vehicle undercover according to claim 1, 2 or 3, The housing further includes vertical wall portions extending downward from the second flat surfaces and the first and second inclined surfaces adjacent to the front and rear of the second flat surfaces, The vehicle undercover is characterized in that the vertical wall portions are provided in a row in the front-rear direction of the vehicle.

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