Air resistance reduction device

Abstract

To provide an air resistance reduction device with reduced air resistance when a vehicle body receives an air flow having cross wind components.SOLUTION: An air resistance reduction device provided on a vehicle 1 having a wheel house 80 that opens to a lateral face part of a vehicle body and houses a part of the wheel RW has: an intake port 101 which opens to an area adjacent to lateral face parts 41, 72 to be an inner surface part 82 at the back of the wheel house; an air outlet 102 which opens to a part that is a lower part 73 of the vehicle body, a back side of the wheel, and where a position in a vehicle width direction overlaps the wheel; and an air flow passage 100 guiding an air flow introduced from the intake port to the air outlet.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an air resistance reduction device that reduces air resistance when a vehicle is affected by a crosswind.

Background Art

[0002] Among the running resistances of an automobile, the proportion of air resistance is high, and it becomes particularly prominent especially during high-speed running. Therefore, reducing the air resistance of the vehicle is extremely important for improving the fuel efficiency of the automobile. As a technology related to improving the aerodynamic performance of a vehicle, for example, in Patent Document 1, a ventilation pipe is provided that communicates from the vicinity of the inner end in the vehicle width direction at the rear wall portion inside the wheel house to the lower surface side of the vehicle body, and the air in the wheel house is discharged so as to merge with the air flow on the vehicle body floor surface, and a device for reducing air resistance is described. In Patent Document 2, in order to suppress a decrease in handling stability due to air flowing into the wheel house from the side portion of the vehicle, an air flow is passed from a first opening formed in a vertical wall portion connected to an inclined wall portion at the rear of the wheel house and extending upward of the vehicle to a second opening formed under the floor on the rear side of the vehicle of the wheel house. This is described. [[ID=M17]] In Patent Document 3, in order to rectify the air flow flowing in the rear wheel house and reduce air resistance, an air intake port and an air discharge port for guiding the air flowing from the rear side of the vehicle to the outside in the vehicle width direction and the lower side of the vehicle are formed in an under cover provided on the rear side of the rear wheel house. This is described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] The development of the aerodynamic performance of such vehicles is usually focused on improving performance when the vehicle is directly facing the airflow. This condition corresponds to the vehicle traveling in a straight line in a windless environment. However, in reality, vehicles often travel at an angle to the airflow (with a crosswind component), and in such cases, it is known that the vehicle's air resistance increases by, for example, several percent. To improve fuel efficiency during actual vehicle operation, it is desired to reduce air resistance to airflow with crosswind components. In view of the above-mentioned problems, the object of the present invention is to provide an air resistance reduction device that reduces air resistance when a vehicle body is subjected to an airflow having a crosswind component. [Means for solving the problem]

[0005] To solve the above-mentioned problems, an air resistance reduction device according to one aspect of the present invention is an air resistance reduction device provided on a vehicle having a wheelhouse that opens on the side of the vehicle body and houses a part of the wheel, comprising: an intake opening on the inner surface of the rear of the wheelhouse that is adjacent to the side of the vehicle body Bottom surface The air outlet is located on the rear side of the wheel and is opened at a location where its position in the vehicle width direction overlaps with that of the wheel, and the air passage is used to guide the airflow introduced from the intake to the air outlet, wherein the air outlet is opened toward the downward side of the vehicle. Furthermore, the air outlet is positioned adjacent to a region where, when the vehicle body is subjected to an airflow having a crosswind component, the airflow velocity in the lower part of the vehicle body is higher than at a point symmetrical with respect to the left-right centerline of the vehicle body on the rear side of the wheel, which is downwind of the crosswind component, and the airflow blown out from the air outlet promotes the formation of turbulence in the airflow flowing in the lower part of the vehicle body on the rear side of the wheel, which is downwind of the crosswind component. When a vehicle is subjected to airflow with a crosswind component, the amount of airflow entering the wheel well increases on the windward side of the crosswind component, and a region is formed where the airflow velocity of the airflow flowing along the underside of the vehicle toward the rear of the vehicle decreases due to the airflow flowing out of the wheel well behind the wheels. On the other hand, such regions where the flow velocity decreases are less likely to form downwind of a crosswind component. When the airflow around a vehicle becomes asymmetrical in this way, the vehicle's drag coefficient (CD) worsens (increases), leading to increased air resistance. In this regard, according to the present invention, by blowing airflow from the outlet, turbulence is generated in the airflow flowing under the vehicle body behind the wheels on the leeward side of the crosswind component, creating a region where the flow velocity decreases. Furthermore, by promoting the growth of this region and strengthening the turbulence, the airflow around the vehicle can be brought closer to a symmetrical state, thereby reducing the air resistance of the vehicle. Furthermore, by positioning the intake adjacent to the side of the vehicle body, the wind pressure from the relatively high-velocity airflow along the side of the wheels allows a large amount of air to be drawn in through the intake, thereby enhancing the effects described above.

[0006] In the present invention, the wheel can be configured to be a rear wheel. According to this method, by suppressing the left-right difference in airflow behind the rear wheels, where the aforementioned phenomenon tends to be more pronounced compared to the front wheels, it is possible to effectively reduce the vehicle's air resistance.

[0007] In the present invention, the air outlet can be configured to be positioned adjacent to a region below the vehicle body where the airflow velocity is higher than a point symmetrical with respect to the left-right centerline of the vehicle body, on the rear side of the wheel, which is downwind of the crosswind component, when the vehicle body is subjected to an airflow having a crosswind component. According to this, by positioning the air outlet adjacent to the region where the airflow velocity under the vehicle body is higher on the rear side of the wheel on the leeward side of the crosswind component compared to the rear side of the wheel on the windward side, the pressure near the air outlet can be made lower than the surrounding pressure, thereby promoting the outflow of air from the air outlet.

[0008] In the present invention, the airflow blown out from the outlet can be configured to promote the formation of turbulence in the airflow flowing under the vehicle body on the rear side of the wheel, which is downwind of the crosswind component. According to this method, by increasing the turbulence of the airflow behind the wheels on the leeward side of the crosswind component and reducing the flow velocity, the difference in airflow between the left and right sides of the vehicle body can be effectively suppressed.

[0009] In the present invention, in a region adjacent to the air outlet of the air flow path, the inclination with respect to the vertical direction when the line connecting the centroids of the flow path cross-section is viewed from the vehicle width direction can be set to 45° or less. According to this, the downward velocity component of the airflow flowing out from the air outlet can be made higher than the horizontal velocity component, and the above-described effect can be effectively obtained. In the present specification and claims, "vertical" shall mean the vertical when the vehicle is traveling on a flat road surface.

Effects of the Invention

[0010] As described above, according to the present invention, it is possible to provide an air resistance reduction device that reduces air resistance when the vehicle body receives an airflow having a crosswind component.

Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 is a side view of the rear part of a vehicle body having an embodiment of an air resistance reduction device to which the present invention is applied. [Figure 2] FIG. 2 is a view taken in the direction of the arrow II-II in FIG. 1. [Figure 3] FIG. 3 is a schematic external perspective view showing a state where the rear part of the rear wheel of the vehicle according to the embodiment is viewed from below the vehicle. [Figure 4] FIG. 4 schematically shows a state when a vehicle which is a comparative example of the present invention receives an airflow from obliquely forward. [Figure 5] FIG. 5 shows an example of the correlation between the yaw angle of the traveling wind and the air resistance coefficient in the vehicles of the embodiment and the comparative example.

Modes for Carrying Out the Invention

[0012] Hereinafter, an embodiment of an air resistance reduction device to which the present invention is applied will be described. The air resistance reduction device according to the embodiment is provided, for example, in a four-wheel automobile having wheels on the front, rear, left, and right. FIG. 1 is a side view of the rear part of a vehicle body having an air resistance reduction device according to the embodiment. Figure 2 is a sectional view taken along the line II-II of Figure 1. Figure 3 is a schematic external perspective view showing the rear part of the rear wheels of the vehicle according to the embodiment as viewed from below the vehicle.

[0013] The vehicle 1 is, for example, a station wagon type passenger car having a vehicle shape such as a two-box type. The vehicle 1 has a floor 10, side sills 20, rear side doors 30, rear quarter parts 40, a roof 50, a tailgate 60, a rear bumper 70, rear wheel houses 80, and the like. The floor 10 is a panel-shaped part provided in the rear half of the vehicle body and constituting the floor surface part of a passenger compartment (cabin) for accommodating passengers and the like.

[0014] The side sill 20 is a structural member extending in the longitudinal direction of the vehicle along the left and right side ends of the floor 10. The front end of the side sill 20 is disposed adjacent to the rear part of a front wheel house (not shown). The rear end of the side sill 20 is disposed adjacent to the front part of the rear wheel house 80.

[0015] The rear side door 30 is an openable and closable door body used for boarding and alighting of rear seat passengers and the like. The front end of the rear side door 30 is rotatably attached via a hinge to a center pillar (not shown). An elevating rear door glass 31 is provided in the upper half of the rear side door 30.

[0016] The rear quarter part 40 is provided from the rear end of the rear side door 30 to the side end of the tailgate 60, and is a part that constitutes the side surface part at the rear of the vehicle body together with the rear side door 30, the side surface part 72 of the rear bumper 70, and the like. The rear quarter part 40 includes a rear quarter panel 41, a rear quarter glass 42, a rear pillar 43, and the like. The rear quarter panel 41 is a sheet metal exterior member (rear fender) that constitutes a part of a monocoque structure (white body, unpainted body). The rear quarter glass 42 is located above the rear quarter panel 41 and behind the rear door glass 31. The rear pillar (D-pillar) 43 is positioned along the rear edge of the rear quarter glass 42 and is the part that connects the upper part of the rear quarter panel 41 to the roof 50.

[0017] The roof 50 is a sheet metal component that forms the upper surface of the passenger compartment and constitutes part of the monocoque structure. The tailgate 60 is an openable and closable door-like structure located at the rear of the vehicle body. The upper end of the tailgate 60, when closed, is rotatably attached to the rear end of the roof 50 via a hinge.

[0018] The rear bumper 70 is an exterior component located at the lower rear of the vehicle body. The rear bumper 70 has a rear section 71, side sections 72, etc. The rear portion 71 extends in the vehicle width direction along the lower end of the tailgate 60 and is the portion facing the rear of the vehicle. The side portion 72 is the portion that extends forward from the left and right ends of the rear portion 71 along the lower edge of the rear quarter panel 41 towards the front of the vehicle. The rear portion 71 and the side portion 72 are integrally molded from, for example, PP resin. Furthermore, a lower surface portion 73 (see Figure 3) is provided in the area on the inner side in the vehicle width direction at the lower part of the side portion 72 of the rear bumper 70, and is positioned facing downwards of the vehicle.

[0019] The rear wheel well 80 is the space in which the rear wheel RW is housed. The rear wheel arch 80 opens into the rear quarter panel 41 on the outer side in the vehicle width direction. The upper edge of the opening of the rear wheel house 80 in the rear quarter panel 41 is formed as a rear wheel arch 81 that is curved upward and convex. The rear of the rear wheel arch 81 is formed continuously to the front edge of the side portion 72 of the rear bumper 70.

[0020] An inner fender 82 (see Figure 3) is provided inside the rear wheel well 80. The inner fender 82 is a component made of, for example, PP resin that forms the inner wall of the rear wheel well 80. In the area behind the rear wheel RW, the inner fender 82 has a concave surface that curves along the wheel arch 81 when viewed from the vehicle width direction.

[0021] A flap 83 is provided at the front of the rear wheel well 80. The flap 83 is a plate-shaped member that protrudes downward from the floor 10 directly in front of the rear wheel well 80. The flap 83 has the function of suppressing collision of the rear wheel RW with the airflow flowing from the front of the vehicle along the underside of the floor 10, thereby reducing the vehicle's air resistance.

[0022] Vehicle 1 further includes a duct 100, which is an air resistance reduction device according to the embodiment. The duct 100 is an air passage that guides a portion of the airflow (wind) generated around the vehicle body when the vehicle is in motion, from the intake 101 to the outlet 102. The duct 100 is located inside the rear bumper 70 and on the rear side of the rear wheel well 80.

[0023] The intake port 101 is located in the area behind the rear wheel RW of the inner fender 82, opening towards the front of the vehicle. The intake port 101 is positioned near the outer end in the vehicle width direction within the rear wheel house 80, such that its position in the vehicle width direction is adjacent to the side portion 71 of the rear bumper 70.

[0024] The air outlet 102 is positioned in the lower part 73 of the rear bumper 70, which forms part of the underside of the vehicle body, and is opening towards the downward side of the vehicle. The air outlet 102 is located adjacent to the rear end of the rear wheel house 80 and on the rear side of the rear wheel RW. The air outlet 102 is positioned in the vehicle width direction at a location that overlaps with the rear wheel RW in at least part of the way. In a plan view of vehicle 1 from above, the position of the air outlet 102 is such that, when vehicle 1 is in motion and is on the leeward side of a crosswind component, the pressure is relatively low relative to the surroundings due to the flow velocity of the airflow F1 flowing under the vehicle floor, and the area around the intake 101 is at low pressure (negative pressure).

[0025] As shown in Figure 1, the duct 100 is an air passage that guides air (airflow) taken in from the intake 101 by the wind pressure (ram pressure) of the airflow F2 that flows rearward along the side of the vehicle body and rear wheel RW when the vehicle 1 is in motion, to the outlet 102. As shown in Figure 1, in a side view of the vehicle as seen from the vehicle width direction, the angle A that the main flow direction of the airflow F3 ejected from the outlet 102 (for example, the direction in which the flow velocity is highest) makes with respect to the vertical direction is preferably small (close to vertical), and is preferably 45° or less. Therefore, when the vehicle is in a steady state and no unsteady behavior such as pitching is occurring, the line connecting the centroids (centers of gravity) of the cross-sectional flow path of the duct 100 in the region adjacent to the outlet 102 of the duct 100 is configured such that, when viewed from the vehicle width direction, the inclination with respect to the vertical direction is 45° or less. To obtain this airflow angle F3, the duct 100 is formed in a curved shape that is convex towards the rear of the vehicle. The lower part of the duct 100 (the area adjacent to the outlet 102) is positioned along the rear surface of the inner fender 82. The main flow direction of airflow F3 can be, for example, aligned with the vertical direction when viewed from the front or rear of the vehicle, but it is not limited to this and may be inclined with respect to the vertical direction. For example, in a front view from the front or rear of the vehicle, the angle that the main flow direction of the airflow F3 ejected from the outlet 102 makes with respect to the vertical direction is preferably small (close to vertical), and is preferably 45° or less.

[0026] The effects of the embodiments will be described below in comparison with the comparative examples of the present invention described below. Comparative example vehicle 1 has the same configuration as vehicle 1 of the embodiment, except that it does not have a duct 100, which is an air resistance reduction device. Figure 4 is a schematic diagram showing the state of a vehicle, which is a comparative example of the present invention, when it receives airflow from the diagonal front. When vehicle 1 is traveling, if it is moving in a straight line in a windless state, vehicle 1 will receive an airflow (wind W) from the front of the vehicle at a relative speed equivalent to its speed. Furthermore, when vehicle 1 is traveling while being subjected to a crosswind, such a driving wind W includes a velocity component in the vehicle width direction (crosswind component). In the example shown in Figure 4, vehicle 1 is subjected to a driving airflow W which has a crosswind component from the left. In the following explanation, the left side in the vehicle's width direction will be referred to as the "windward side," and the right side as the "leeward side."

[0027] When vehicle 1 is subjected to a crosswind while in motion, an angle θ occurs between the direction of the wind W acting on vehicle 1 and the longitudinal direction of vehicle 1. In other words, vehicle 1 receives the wind W from the diagonal front side. For example, if vehicle 1 is traveling at a speed of, say, 80 km / h and is subjected to a crosswind of 2 m / s, then θ will be approximately 5°. When subjected to crosswinds that cause such a deflection angle θ, the vehicle's air resistance increases compared to when traveling straight without crosswinds (when there is no deflection angle θ).

[0028] In Figure 4, the region where the relative velocity of the airflow to the vehicle body is below a predetermined value (low-velocity region) is indicated by shading. In the following explanation, the windward and leeward rear wheels (RW) will be denoted by the subscripts u and d, respectively. In comparative example vehicle 1, relatively large turbulence occurs behind the left rear wheel RWu, which is on the windward side, and a region R1 with low flow velocity is formed. On the other hand, behind the right rear wheel RWd, which is the downwind side, the turbulence in the airflow is relatively smaller compared to the left side, and the airflow velocity between the underbody and the road surface towards the rear of the vehicle is higher than behind the right rear wheel RWu, which is the upwind side. This phenomenon is caused by the fact that the amount of airflow into the rear wheel well 80 during crosswinds is significantly greater on the windward side. When the airflow around vehicle 1 becomes asymmetrical in this way, it contributes to increased air resistance.

[0029] In contrast, in this embodiment, at the rear of the rear wheelhouse 80 on the leeward side, the airflow flowing along the side F2 of the vehicle body and rear wheel RW, which has a relatively high flow velocity, is taken in from the intake 101 into the duct 100 using its wind pressure, and the airflow is sucked out by the negative pressure generated by the high-velocity airflow F1 along the underside of the floor 10, thereby forming an airflow F3 that is ejected downward from the outlet 102. This induces turbulence in the airflow behind the downwind rear wheel RWd, forming turbulent flow with vortices. This creates a region with reduced flow velocity (for example, region R2 shown as a dashed ellipse in Figure 4), which can then be expanded, and the turbulence within this region can be intensified. Therefore, by making the airflow around vehicle 1 closer to a state of left-right equality, the aerodynamic balance can be improved and the air resistance of vehicle 1 can be reduced. In this embodiment, in order to obtain the effects described above, the air outlet 102 is positioned above a region where the airflow velocity F1 is higher than at a location symmetrical in the vehicle width direction (upwind side) behind the rear wheel RW on the leeward side.

[0030] Furthermore, on the upwind side, the airflow velocity behind the rear wheel RWu is low, making it difficult for the aforementioned negative pressure to form. As a result, no airflow is formed in the duct 100, or if it is formed, the flow rate and velocity are lower than on the downwind side. Therefore, in this embodiment, the above-mentioned effects can be obtained with a simple and passive configuration without controlling the flow rate of the left and right ducts 100 by, for example, an opening and closing mechanism.

[0031] Figure 5 shows an example of the correlation between the angle of airflow deflection and the drag coefficient in the vehicles of the embodiment and comparative example. In Figure 5, the horizontal axis represents the angle of deviation, and the vertical axis represents the drag coefficient C. DThis indicates the amount of increase (deterioration) relative to a state where the argument of the value is 0. The data for the embodiment is shown with solid lines, and the data for the comparative example is shown with dashed lines. As shown in Figure 5, in both the embodiment and the comparative example, the air resistance coefficient C increases with increasing angle θ. D Although it tends to increase, in this embodiment, for example, when the deflection angle θ is 5°, the air resistance coefficient C is compared to the comparative example. D The increase has been suppressed by approximately 10%.

[0032] As described above, the following effects can be obtained according to this embodiment. (1) By blowing airflow F3 downward from the outlet 102 of the duct 100, turbulence is generated in the airflow F1 flowing under the vehicle body behind the rear wheel RWu on the leeward side of the crosswind component, forming a region where the flow velocity decreases. Furthermore, by promoting the growth of this region and strengthening the turbulence of the airflow within this region, the airflow around the vehicle 1 can be brought closer to a symmetrical state, thereby reducing the air resistance of the vehicle 1. Furthermore, by positioning the intake 101 adjacent to the side portion 72 of the rear bumper 70, a large amount of air can be taken in through the intake 101 by the wind pressure of the relatively high-velocity airflow F2 flowing along the side of the vehicle body and the outer surface of the rear wheel RW. This increases the flow velocity and flow rate of the airflow F3 ejected from the outlet 102, thereby promoting the effects described above. (2) By providing the duct 100 at the rear of the rear wheel house 80, the left-right difference in airflow behind the rear wheel RW, which tends to be more pronounced than that behind the front wheel, can be suppressed, thereby effectively reducing the air resistance of the vehicle 1. (3) By positioning the outlet 102 adjacent to a region where the airflow velocity under the vehicle body is higher than on the windward side, on the rear side of the rear wheel RWd on the leeward side of the crosswind component, the pressure near the outlet 102 can be made lower than the surrounding pressure, thereby promoting the outflow of airflow F3 from the outlet 102. (4) The airflow F3 blown out from the outlet 102 promotes the formation of turbulence in the airflow F1 flowing under the vehicle body behind the rear wheel RW, which is on the leeward side of the crosswind component. This increases the region of turbulence behind the rear wheel RWd, which is on the leeward side of the crosswind component, and strengthens the turbulence, thereby reducing the flow velocity and effectively suppressing the difference in airflow between the left and right sides of the vehicle body.

[0033] (modified version) The present invention is not limited to the embodiments described above, and various modifications and changes are possible, all of which fall within the technical scope of the present invention. The configuration of the vehicle and the air resistance reduction device is not limited to the embodiments described above and can be modified as appropriate. For example, the vehicle type and shape, as well as the shape, number, and arrangement of each element constituting the air resistance reduction device, can be changed as appropriate. Furthermore, in this embodiment, the air resistance reduction device is provided at the rear of the wheel well housing the rear wheel, but it may be provided at the rear of the wheel well housing the front wheel, either in place of or together with the air resistance reduction device. [Explanation of Symbols]

[0034] 1 vehicle, 10 floors 20 Side sill 30 Rear side door 31 Rear door glass 40 Rear quarter panel 41 Rear quarter panel 42 Rear quarter glass 43 Rear pillar 50 Roof 60 Tailgate 70 Rear Bumper 71 Rear section 72 Side section 73 Underside 80 Rear wheel well 81 Rear wheel arch 82 Inner fender 83 flaps 100 ducts 101 Inlet 102 Outlet W Driving airflow F1, F2, F3 airflow

Claims

1. An air resistance reduction device provided on a vehicle having a wheel well that opens on the side of the vehicle body and houses a part of the wheel, An intake opening in the inner surface of the rear of the wheelhouse, in a region adjacent to the side surface, An air outlet is provided on the underside of the vehicle body, on the rear side of the wheel, and at a location where the position of the wheel and the vehicle width direction overlap. An air passage that guides the airflow introduced from the intake to the outlet, It has, The aforementioned air outlet is open toward the lower side of the vehicle. The aforementioned air outlet is positioned adjacent to a region below the vehicle body where the airflow velocity is higher than a point symmetrical with respect to the left-right centerline of the vehicle body, on the rear side of the wheels, which is downwind of the crosswind component, when the vehicle body is subjected to an airflow having a crosswind component. The airflow blown out from the aforementioned outlet promotes the formation of turbulence in the airflow flowing under the vehicle body on the rear side of the wheel, which is downwind of the crosswind component. An air resistance reduction device characterized by the following.

2. The aforementioned wheel is a rear wheel. The air resistance reduction device according to claim 1, characterized by the following:

3. In the region of the air passage adjacent to the outlet, the inclination of the line connecting the centroids of the cross-section of the passage with respect to the vertical when viewed from the vehicle width direction is 45° or less. An air resistance reduction device according to claim 1 or claim 2, characterized by the above.

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