Undercover
The undercover's angled through holes with rectifying walls address the inefficiency of heat dissipation and stability issues by optimizing gas flow velocity and direction, enhancing heat dissipation and stability.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NIFCO INC
- Filing Date
- 2025-12-05
- Publication Date
- 2026-07-23
AI Technical Summary
Existing vehicle undercovers do not efficiently dissipate heat through their through holes, which are orthogonal to the vehicle's front-rear direction, leading to suboptimal heat dissipation and potential stability issues.
The undercover features through holes that intersect at an angle other than orthogonal with the vehicle's front-rear direction, equipped with rectifying walls that protrude downward from the edges of these holes, forming a flow path that enhances gas flow velocity and directionality, thereby improving heat dissipation and stability.
The solution increases the efficiency of heat dissipation from the vehicle's interior by enhancing gas flow velocity and aligning it with the vehicle's travel direction, thereby improving driving stability and reducing temperature fluctuations.
Smart Images
Figure JP2025042439_23072026_PF_FP_ABST
Abstract
Description
Undercover
[0001] The present disclosure relates to an undercover attached to a vehicle body of an automobile.
[0002] An example of an undercover for a vehicle is formed from a resin panel member. The undercover for a vehicle has one or more through holes penetrating the panel member. The through holes are formed in the panel member such that the longitudinal direction of the through holes intersects at an angle other than orthogonal with respect to the front-rear direction of the automobile to which the undercover for a vehicle is assembled (see, for example, Patent Document 1).
[0003] Japanese Patent Application Laid-Open No. 2020-82939
[0004] In the undercover for a vehicle, it is required that heat dissipation through the through holes communicating the inside and outside of the vehicle body be performed more efficiently.
[0005] In one aspect, the undercover is attached to the lower surface of the vehicle body included in the automobile. The undercover includes a main body portion having a plate shape, a through hole penetrating the main body portion along the vertical direction of the vehicle body and communicating the inside and outside of the vehicle body, the through hole extending along an extending direction intersecting the left-right direction of the vehicle body, and a rectifying wall protruding downward from the vehicle body from a side edge of the through hole extending along the extending direction.
[0006] Figure 1 is a plan view showing an under cover of one embodiment attached to the underside of a vehicle body. Figure 2 is a perspective view showing the structure of the under cover shown in Figure 1. Figure 3 is a plan view showing the two through holes of the under cover shown in Figure 2, along with a pair of rectifying walls protruding from the edges of the through holes. Figure 4 is a cross-sectional view showing the structure along the line IV-IV shown in Figure 3. Figure 5 is a cross-sectional view showing the structure along the line V-V shown in Figure 3. Figure 6 is a plan view showing the structure of the under cover of Test Example 1. Figure 7 is a plan view showing the structure of the under cover of Test Example 2. Figure 8 is a plan view showing the structure of the under cover of Test Example 3. Figure 9 is a graph showing the results of measuring the temperature inside the vehicle body to which the under cover of Test Example 1 was attached. Figure 10 is a graph showing the results of measuring the temperature inside the vehicle body to which the under cover of Test Example 2 was attached. Figure 11 is a graph showing the results of measuring the temperature inside the vehicle body to which the under cover of Test Example 3 was attached.
[0007] An embodiment of the under cover will be described with reference to Figures 1 to 11. [Under cover] As shown in Figure 1, the under cover 10 is attached to the underside BB of the vehicle body B of the automobile. When the under cover 10 is attached to the vehicle body B, at least a part of the under cover 10 is located below the engine. The under cover 10 is attached, for example, to an under cover bracket provided on the vehicle body B.
[0008] As shown in Figure 2, the under cover 10 comprises a main body portion 10A having a plate shape, through holes 10B, and a pair of flow-straightening walls 10C for each through hole 10B. In this embodiment, the main body portion 10A has a substantially rectangular flat plate shape. The main body portion 10A may have a plate shape that is partially curved, or a plate shape that is partially projecting downward.
[0009] The through-hole 10B formed in the main body portion 10A penetrates the main body portion 10A in the thickness direction of the main body portion 10A and extends along the extension direction within the main body portion 10A. Therefore, when the under cover 10 is attached to the vehicle body B, the through-hole 10B penetrates the main body portion 10A along the vertical direction of the vehicle body B, thereby connecting the inside of the vehicle body B with the outside of the vehicle body B. Also, when the under cover 10 is attached to the vehicle body B, the through-hole 10B extends along the extension direction that intersects with the left-right direction of the vehicle body B. In this embodiment, the through-hole 10B has a rectangular shape that extends along the extension direction. Also, in this embodiment, the under cover 10 has a plurality of through-holes 10B. When the under cover 10 has a plurality of through-holes 10B, the number of through-holes 10B may be even.
[0010] The under cover 10 of this embodiment is provided with four through holes 10B. It is possible to set an axis of symmetry that passes through the center of the main body 10A in the left-right direction and extends along the front-rear direction. In this case, of the four through holes 10B, the two through holes 10B located at the ends are line-symmetric with respect to the axis of symmetry. Also, the two through holes 10B located in the center, sandwiched between the two through holes 10B located at the ends, are line-symmetric with respect to the axis of symmetry. In the left-right direction, the four through holes 10B are arranged at approximately equal intervals.
[0011] Figure 3 is a plan view showing the leftmost and second-to-left through-holes 10B of the four through-holes 10B provided in the under cover 10, together with the flow straightening wall 10C.
[0012] As shown in Figure 3, a pair of straightening walls 10C corresponding to a single through-hole 10B are spaced apart in the left-right direction. Each straightening wall 10C protrudes from the edge 10BE of the through-hole 10B that extends along the direction of extension of the through-hole 10B. When the under cover 10 is attached to the vehicle body B, each straightening wall 10C protrudes downward from the vehicle body B. Each straightening wall 10C extends along the edge that extends along the direction of extension. Viewed from a viewpoint opposite to the plane where the main body 10A extends, it is possible to set a plane of symmetry that is determined by the direction of extension and the vertical direction of the through-hole 10B, and is located in the center between the pair of straightening walls 10C in a direction perpendicular to the direction of extension. In this case, the pair of straightening walls 10C are symmetrical with respect to the plane of symmetry. As a result, a flow path extending along the direction of extension is formed between the pair of straightening walls 10C.
[0013] The under cover 10 of this disclosure is provided with a pair of flow-straightening walls 10C that protrude from a pair of edges 10BE of the through hole 10B that extend along the direction of the through hole 10B. As a result, gas flowing from the through hole 10B to the outside of the vehicle body B flows between the flow-straightening walls 10C along the direction of the through hole 10B. This increases the gas flow velocity below the through hole 10B compared to when the under cover 10 is not provided with flow-straightening walls 10C, making it easier for gas to flow from inside the vehicle body B to outside the vehicle body B. As a result, the efficiency of dissipating heat from inside the vehicle body B can be increased.
[0014] The angle formed by the extending direction of the through-hole 10B and the longitudinal direction of the vehicle body B may be between 0° and 45°. That is, the angle formed by the extending direction of the through-hole 10B and the lateral direction of the vehicle body B may be between 45° and 90°. In this case, the gas flowing from the through-hole 10B out of the vehicle body B is more likely to flow towards the rear of the vehicle body B along the extending direction of the through-hole 10B. As a result, the gas flows in line with the direction of travel of the vehicle, thereby improving driving stability.
[0015] From the standpoint of improving driving stability, the angle formed by the extending direction of the through-hole 10B and the longitudinal direction of the vehicle body B is preferably 20° or less, and more preferably 15° or less.
[0016] When viewed from a viewpoint facing the lower surface BB of the vehicle body B, the extending direction of the through-hole 10B may have an inclination such that the distance between the center of the main body 10A and the through-hole 10B in the left-right direction increases as it moves towards the rear. In this embodiment, the extending direction of the through-hole 10B has an inclination such that the distance between the center of the main body 10A and the through-hole 10B in the left-right direction increases as it moves towards the rear.
[0017] Because the pair of rectifier walls 10C extend along the direction of extension, the direction of fluid flow from the front to the rear of the vehicle body B tends to follow the pair of rectifier walls 10C. As a result, heat is more easily dissipated from inside the vehicle body B compared to the case where the pair of rectifier walls 10C extend along the longitudinal direction.
[0018] The inclination in the extension direction relative to the front-to-back direction may be the same for all through holes 10B, or it may differ for each through hole 10B. In this embodiment, of the four through holes 10B, the inclinations of the two through holes 10B located at the left-right ends are equal to each other, and the inclinations of the two through holes 10B sandwiched between the two through holes 10B located at the left-right ends are also equal to each other. Furthermore, of the four through holes 10B, the inclination of the two through holes 10B located at the left-right ends is greater than the inclination of the two through holes 10B sandwiched between the two through holes 10B located in the center.
[0019] Gas flows into the vehicle body B from components located in front of the under cover 10. Gas also flows into the vehicle body B through, for example, through holes in the front grille. The gas that flows into the vehicle body B tends to flow outwards as it moves away from the center of the vehicle body B in the left-right direction. In this respect, the inclination of the through holes 10B located at the left-right ends is greater than the inclination of the two through holes 10B located in the center, which makes it easier for gas to flow from inside the vehicle body B to outside the vehicle body B.
[0020] The maximum value of the distance D10C between the pair of rectifier walls 10C in the left-right direction may be less than the distance D10. Distance D10 is the distance between a member other than the pair of rectifier walls 10C corresponding to one through hole 10B and the rectifier wall 10C of the pair that is closer to the member. The member other than the pair of rectifier walls 10C corresponding to one through hole 10B is positioned so as to overlap with at least one of the pair of rectifier walls 10C in the vertical direction.
[0021] For example, in the example shown in Figure 3, the members other than the pair of rectifier walls 10C are rectifier walls 10C rising from the edges 10BE of other through holes 10B adjacent to each other in the left-right direction. Alternatively, the members other than the pair of rectifier walls 10C may be, for example, parts within the main body 10A that protrude downward toward the vehicle body B.
[0022] The distance D10C between a pair of straightening walls 10C rising from the edge 10BE of one through-hole 10B is smaller than the distance between other members and the straightening walls 10C. This makes it possible to make the flow velocity of the gas flowing out of one through-hole 10B to the outside of the vehicle body B and then flowing between the straightening walls 10Cs higher than the flow velocity of the gas flowing between other members and the straightening walls 10Cs.
[0023] Figure 4 shows the cross-sectional structure of the undercover 10 along the line IV-IV in Figure 3. That is, Figure 4 shows the cross-sectional structure of the undercover 10 along a plane determined by the opposing direction of a pair of rectifying walls 10C flanking a single through-hole 10B, and the vertical direction.
[0024] As shown in Figure 4, in a cross-sectional view in a plane determined by the opposing directions and vertical direction of the pair of rectifier walls 10C, each rectifier wall 10C may have a curvature such that the distance D10C between the pair of rectifier walls 10C narrows downwards at its base end connected to the main body 10A. This makes it easier for gas to flow along the base end of the rectifier wall 10C compared to the case where each rectifier wall 10C rises perpendicular to the main body 10A. In other words, the amount of gas that collides with the base end of the rectifier wall 10C is reduced. As a result, heat inside the vehicle body B is more easily discharged to the outside of the vehicle body B along with the gas inside the vehicle body B.
[0025] Each rectifier wall 10C comprises a curved portion 10CA and a straight portion 10CB. The curved portion 10CA is connected to the main body portion 10A and has a curvature such that its center of curvature is located outside the space between the pair of rectifier walls 10C. The straight portion 10CB is connected to the end of the curved portion 10CA opposite to the end connected to the main body portion 10A and extends along the vertical direction.
[0026] Each rectifier wall 10C may have an inclination at its base end connected to the main body 10A such that the distance D10C between a pair of rectifier walls 10C narrows downwards. In this case, each rectifier wall 10C may have an inclined portion that is inclined with respect to the main body 10A at a predetermined angle instead of a curved portion 10CA.
[0027] Figure 5 shows the cross-sectional structure of the under cover 10 along the line V-V in Figure 3. That is, Figure 5 shows the cross-sectional structure of the under cover 10 along the plane determined by the extending direction and vertical direction of the through hole 10B.
[0028] As shown in Figure 5, each rectifier wall 10C has an inclined surface 10CC at its front end. The inclined surface 10CC has an inclination such that the width of the rectifier wall 10C along the vertical direction increases in the direction from the front to the rear of the vehicle body B. As a result, compared to the case where the front end of the rectifier wall 10C has a vertical surface rising perpendicular to the main body 10A, the rectifier wall 10C is less likely to collide with curb blocks or the ground when the vehicle is moving forward. Furthermore, even if the rectifier wall 10C does collide with curb blocks or the ground, the rectifier wall 10C is less likely to be damaged.
[0029] The under cover 10 in this embodiment is formed from, for example, a metal plate. The through holes 10B in the under cover 10, and the rectifying walls 10C rising from the edges 10BE of each through hole 10B, are formed by press working on the metal plate. The under cover 10 may also be formed from synthetic resin. In this case, the under cover 10 is formed, for example, by injection molding, press molding, or stamping molding using synthetic resin.
[0030] Furthermore, if the under cover 10 is formed from a metal plate, as shown in Figure 3, at each end of the through hole 10B in the extending direction, cuts may be formed on both the left and right sides that extend outward from the pair of fold lines for forming the pair of rectifying walls 10C. This makes it possible to improve the bending accuracy at the base end of the rectifying wall 10C.
[0031] [Test Examples] Test examples will be described with reference to Figures 6 to 11. [Test Example 1] As shown in Figure 6, the under cover 100 of Test Example 1 comprises a main body 100A, through holes 100B, and inclined pieces 100C. The main body 100A has a plate shape. The through holes 100B penetrate the main body 100A along the vertical direction of the vehicle body B. The under cover 100 has three through holes 100B arranged in the right column and three through holes 100B arranged in the left column. The extending direction of each through hole 100B intersects the left-right direction and has an inclination such that the distance from the center of the main body 10A in the left-right direction becomes smaller towards the rear.
[0032] The under cover 100 is provided with one inclined piece 100C corresponding to each through hole 100B. The inclined piece 100C rises from the edge of the through hole 100B that extends along the extending direction and is located forward, and covers the through hole 100B. The inclined piece 100C has an inclination such that the distance between the inclined piece 100C and the main body 100A in the vertical direction increases towards the rear.
[0033] [Test Example 2] As shown in Figure 7, the under cover 10 of Test Example 2 differs from the under cover 10 of the embodiment described above in the following respects. Specifically, in the under cover 10 of Test Example 2, the extension direction of the through holes 10B is along the front-to-back direction. As a result, the pair of flow-straightening walls 10C provided by each through hole 10B also extend along the front-to-back direction. In the left-to-right direction, the four through holes 10B are arranged at equal intervals.
[0034] [Test Example 3] As shown in Figure 8, in the under cover 10 of Test Example 3, similar to the under cover 10 of the embodiment described above, the extending direction of the through holes 10B is inclined with respect to the front-rear direction. The extending direction of each through hole 10B has an inclination such that the distance between the center of the main body 10A and the through hole 10B in the left-right direction increases as it moves towards the rear.
[0035] [Evaluation Method] In each test example, the undercovers 10 and 100 were attached to the vehicle body B, thereby positioning the undercovers 10 and 100 below the engine. Two thermocouples were placed in the space between the undercovers 10 and 100 and the engine. In test examples 2 and 3, the first thermocouple was placed between the leftmost through-hole 10B and the second through-hole 10B from the left, as viewed from a viewpoint opposite to the plane where the main body 10A extends. In test examples 2 and 3, the second thermocouple was placed between the second through-hole 10B from the left and the third through-hole 10B from the left. In test example 1, the two thermocouples were placed in the same position as in test examples 2 and 3, within the space between the undercover 100 and the engine. In test examples 2 and 3, the two thermocouples were positioned such that the distance between the second thermocouple and the third through-hole 10B from the left was smaller than the distance between the first thermocouple and the second through-hole 10B from the left in the left-right direction.
[0036] Vehicles equipped with undercovers 10 and 100 for each test example were driven on a circuit under the same driving conditions, and the detected values of the first and second thermocouples were monitored. [Evaluation Results] For each test example, the detection results of the first and second thermocouples were as shown in Figures 9 to 11. Figure 9 shows the detection results for the vehicle equipped with undercover 100 in Test Example 1, Figure 10 shows the detection results for the vehicle equipped with undercover 10 in Test Example 2, and Figure 11 shows the detection results for the vehicle equipped with undercover 10 in Test Example 3. In Figures 9 to 11, the detected value of the first thermocouple is shown by a dashed line, and the detected value of the second thermocouple is shown by a solid line.
[0037] As shown in Figure 9, in the vehicle equipped with the under cover 100 of Test Example 1, it was observed that the detected value of the first thermocouple increased from approximately 45°C to approximately 50°C as the vehicle's operating period lengthened. Furthermore, it was observed that the detected value of the second thermocouple increased from approximately 50°C to approximately 60°C as the vehicle's operating period lengthened.
[0038] As shown in Figure 10, in the vehicle equipped with the under cover 10 of Test Example 2, it was observed that the detected value of the first thermocouple remained at approximately 55°C even when the vehicle was driven for an extended period. Furthermore, it was observed that the detected value of the second thermocouple increased from approximately 35°C to approximately 60°C as the vehicle's driving period lengthened. However, in Test Example 2, compared to the vehicle equipped with the under cover 100 of Test Example 1, multiple downward-convex peaks were observed in the detected value of the second thermocouple. In other words, in the vehicle equipped with the under cover 10 of Test Example 2, compared to the vehicle equipped with the under cover 100 of Test Example 1, the detected value of the second thermocouple dropped significantly in accordance with the vehicle's braking. Therefore, it can be said that the under cover 10 of Test Example 2 facilitates the outflow of gas from inside the vehicle body B to outside the vehicle body B compared to the under cover 100 of Test Example 1, and as a result, the efficiency of heat dissipation from inside the vehicle body B to outside the vehicle body B is increased.
[0039] As shown in Figure 11, in the vehicle equipped with the under cover 10 of Test Example 3, it was observed that the detected value of the first thermocouple remained at approximately 50°C even when the vehicle was driven for an extended period. Furthermore, it was observed that the detected value of the second thermocouple remained between approximately 35°C and approximately 45°C even when the vehicle was driven for an extended period. Moreover, in the vehicle equipped with the under cover 10 of Test Example 3, it was observed that the detected value of the second thermocouple dropped more significantly in accordance with the vehicle's braking compared to the vehicle equipped with the under cover 10 of Test Example 2. Therefore, it can be said that the under cover 10 of Test Example 3 facilitates the outflow of gas from inside the vehicle body B to outside the vehicle body B, and as a result, the efficiency of heat dissipation from inside the vehicle body B to outside the vehicle body B is increased.
[0040] As described above, according to one embodiment of the under cover, the following effects can be obtained. (1) Since the under cover 10 includes the fairing wall 10C, the gas flowing out of the vehicle body B from the through hole 10B flows between the fairing walls 10C along the extending direction of the through hole 10B. As a result, the flow velocity of the gas increases below the through hole 10B, making it easier for the gas to flow from inside the vehicle body B to the outside of the vehicle body B. As a result, the efficiency of discharging the heat inside the vehicle body B can be enhanced.
[0041] (2) When the angle formed by the extending direction and the front-rear direction is 0° or more and 45° or less, the gas flowing out of the vehicle body B from the through hole 10B easily flows toward the rear of the vehicle body B along the extending direction of the through hole 10B. As a result, since the gas flows along the traveling direction of the automobile, the traveling stability can be enhanced.
[0042] (3) The extending direction of the through hole 10B may have an inclination such that the distance between the center of the main body portion 10A in the left-right direction and the through hole 10B increases toward the rear. In this case, since the pair of fairing walls 10C extends along the extending direction, the flow direction of the fluid flowing from the front to the rear of the vehicle body B easily follows the pair of fairing walls 10C. As a result, heat is more easily discharged from inside the vehicle body B than when the pair of fairing walls 10C extends along the front-rear direction.
[0043] (4) The distance D10C between the pair of fairing walls 10C rising from the edge 1 of one through hole 10B may be smaller than the distance between the other member and the fairing wall 10C. In this case, the flow velocity of the gas flowing out of the vehicle body B from one through hole 10B and then flowing between the fairing walls 10C can be made higher than the flow velocity of the gas flowing between the other member and the fairing wall 10C.
[0044] (5) When each fairing wall 10C has a curvature such that the distance between the pair of fairing walls 10C narrows downward at the base end connected to the main body portion 10A, the gas easily flows along the base end of the fairing wall 10C. Therefore, the heat inside the vehicle body B is easily discharged to the outside of the vehicle body B together with the gas inside the vehicle body B.
[0045] Incidentally, the above-described embodiments can be implemented with the following modifications. [Rectifying wall] - The base end of each rectifying wall 10C may have a shape that rises perpendicular to the main body portion 10A. Even in this case, a pair of rectifying walls 10C facing each through-hole 10B rise from a side extending along the extending direction among the edges 10BE of the through-hole 10B, whereby the effects according to the above-described (1) can be obtained.
[0046] - As described above, the extending direction of each through-hole 10B may be a direction along the front-rear direction. That is, the extending direction may be parallel to the front-rear direction. Alternatively, the extending direction may have an inclination such that the distance between the center of the main body portion 10A in the left-right direction and the through-hole 10B becomes smaller toward the rear. Even in any case, a pair of rectifying walls 10C facing each through-hole 10B rise from a side extending along the extending direction among the edges 10BE of the through-hole 10B, whereby the effects according to the above-described (1) can be obtained.
[0047] - The angle formed by the extending direction of the through-hole 10B and the front-rear direction of the vehicle body B may be greater than 45° and less than 90°. Even in this case, a pair of rectifying walls 10C facing each through-hole 10B rise from a side extending along the extending direction among the edges 10BE of the through-hole 10B, whereby the effects according to the above-described (1) can be obtained.
[0048] - The under cover 10 may include only one rectifying wall 10C for one through-hole 10B. In this case, for example, the under cover 10 may include only the rectifying wall 10C that rises from the left side among the sides extending along the extending direction, or may include only the rectifying wall 10C that rises from the right side. Alternatively, the under cover 10 may include both the rectifying wall 10C that rises from the left side and the rectifying wall 10C that rises from the right side among the sides extending along the extending direction.
[0049] Even if the under cover 10 is equipped with only one straightening wall 10C for each through-hole 10B, the gas flowing from the through-hole 10B out of the vehicle body B flows along the direction of extension of the through-hole 10B. As a result, the gas flow velocity below the through-hole 10B is higher than when the under cover 10 is not equipped with a straightening wall 10C, making it easier for gas to flow from inside the vehicle body B to outside the vehicle body B. Consequently, the efficiency of dissipating heat from inside the vehicle body B can be increased.
Claims
1. An under cover configured to be attached to the underside of the body of an automobile, comprising: a main body having a plate shape; a through hole that penetrates the main body along the vertical direction of the vehicle body and communicates the inside of the vehicle body with the outside of the vehicle body, the through hole extending along an extending direction that intersects the left-right direction of the vehicle body; and a flow-straightening wall projecting downward toward the vehicle body from a first edge of the edge of the through hole that extends along the extending direction.
2. The under cover according to claim 1, wherein the angle formed by the extending direction of the through hole and the longitudinal direction of the vehicle body is 0° or more and 45° or less.
3. The under cover according to claim 2, as viewed from a viewpoint opposite to the lower surface of the vehicle body, the extending direction of the through hole has an inclination such that the distance between the center of the main body and the through hole in the left-right direction increases as it moves towards the rear.
4. The under cover according to any one of claims 1 to 3, wherein the through hole is a first through hole among a plurality of through holes, the straightening wall is a first straightening wall, and each through hole further comprises a second straightening wall projecting downward toward the vehicle body from a second side of the edge of the through hole that extends along the extending direction, and the first straightening wall and the second straightening wall are spaced apart in the left-right direction.
5. The undercover according to claim 4, wherein the maximum value of the distance between the first and second flow straightening walls in the left-right direction is smaller than the distance between a member other than the first and second flow straightening walls, which is positioned to overlap with at least one of the first and second flow straightening walls in the up-down direction, and the flow straightening wall of the first and second flow straightening walls that is closer to the member.
6. The under cover according to claim 4, wherein, in a cross-sectional view in a plane determined by the opposing directions in which the first and second rectifying walls face each other and the vertical direction, each rectifying wall has a curvature or inclination at its base end connected to the main body such that the distance between the first and second rectifying walls narrows toward the downward direction of the vehicle body.