Vehicle undercarriage

Abstract

To provide a vehicle lower part structure that prevents hot wind from a fan from being guided to an upper part of a heating element and cools the heating element to the upper surface thereof with underfloor wind during normal running of a vehicle and meanwhile allows the wind of the fan to be guided to the heating element without the underfloor wind and cools the heating element when the vehicle is stopped.SOLUTION: A vehicle lower part structure includes a fan 14 configured to generate wind that cools a heat source member 13 on the front side of a heating element 42 and travels rearward toward a space 53 between an undercover 50 and a floor panel 16. The undercover 50 includes: a hole portion 54 through which travel wind below the undercover 50 is guided from a position forward of the heating element 42 during traveling of a vehicle; and a slop portion 55 extending upward from a front end portion 54a of the hole portion 54 toward the rear side. In a region in a front-rear direction where the slop portion 55 is disposed, a wall member 56 is disposed overlapped with an upper portion of the heating element 42 in vehicle front view. A space portion 57 allowing for the inflow of wind from the fan 14 is provided between an upper end portion of the slope portion 55 and a lower end of the wall member 56.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a vehicle underbody structure in which a heat generating element provided below a floor panel of a vehicle is cooled by airflow from a fan or airflow while the vehicle is running under the floor. [Background technology]

[0002] Conventionally, a vehicle understructure has been known in which a heating element such as a DC-DC converter (direct current voltage converter) is provided below the floor panel of the vehicle, an undercover fixed to the vehicle body is provided below the heating element, and a fan (see radiator fan) is provided in front of the heating element to cool a heat source component such as a radiator and generate airflow toward the rear of the vehicle in the space between the undercover and the floor panel.

[0003] When the vehicle is stopped, such as when idling, the wind from the fan can adequately cool the heat-generating body. However, for example, when towing a leisure boat or the like to the rear of the vehicle via a trailer hitch, the load increases while the vehicle is moving, and the wind generated by the fan becomes hot, making it difficult to cool the heat-generating body with this hot air.

[0004] Therefore, as disclosed in Patent Document 1, a structure has already been invented in which a hole is formed in the undercover and the underfloor airflow flowing in through the hole is used to cool the heat generating element.

[0005] However, in the conventional structure disclosed in Patent Document 1, the hot air generated by the fan flowing toward the rear of the vehicle blocks (i.e., blocks) the underfloor airflow flowing in through the hole, making it impossible to introduce the underfloor airflow up to the top of the heat-generating element, and therefore failing to sufficiently cool the heat-generating element. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-58383 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, this invention aims to provide an undercarriage structure for a vehicle that, when the vehicle is running normally, prevents hot air from the fan from being directed toward the top of the heat-generating element, allowing the heat-generating element to be cooled down to its upper surface by the airflow from under the floor when the vehicle is running, and, when the vehicle is stopped, allows the air from the fan to be directed toward the heat-generating element to cool the heat-generating element even when there is no airflow from under the floor. [Means for solving the problem]

[0008] The present invention relates to a vehicle undercarriage including a heating element provided below a floor panel of the vehicle, an undercover fixed to a vehicle body and provided below the heating element, and a fan in front of the heating element that cools a heat source member and generates airflow in a rearward direction in a space between the undercover and the floor panel, wherein the undercover has a hole that introduces airflow from under the undercover from a position forward of the heating element when the vehicle is traveling, and a slope that slopes upward from the front end of the hole toward the rear, and a wall member that is provided in a vehicle longitudinal direction region where the slope is provided, overlapping an upper portion of the heating element in a front view of the vehicle, and a space that allows airflow from the fan to flow in between an upper end of the slope portion and a lower end of the wall member. The upper end of the slope portion and the center of the heating element in the vehicle vertical direction overlap in a front view of the vehicle, and the slope portion is located on an extension line of the wall member in a side view of the vehicle. The vehicle undercarriage is characterized by:

[0009] The heating element may be, for example, an electric control part such as a DC-DC converter (direct current to direct current converter) or a drive system part such as a differential. Furthermore, the heat source member may be, for example, an air-cooling element of an internal combustion engine such as a radiator, or in the case of an electric vehicle, an air-cooling element of a motor.

[0010] With this invention, when the vehicle is running normally, the wall member prevents the wind (hot air) from the fan from being directed to the top of the heating element, and the underfloor running wind is guided from the hole along the underside of the slope section to the top of the heating element, thereby cooling not only the underside of the heating element but also the top of the heating element.

[0011] On the other hand, when the vehicle is stopped, the air from the fan that flows in from the space hits the heat generating element, so the heat generating element can be cooled even without wind from running. The sloped portion allows the outside air to be drawn in without disturbing the flow of wind generated when the vehicle is traveling under the floor, due to the viscosity of the air flowing along the underside of the sloped portion.

[0012] As an aspect of the present invention, an opening suppression portion may be provided extending upward from a rear end portion of the hole portion. According to this invention, the opening prevention portion prevents water kicked up from the road surface by the wheels and moisture contained in muddy water from entering through the hole, thereby preventing the heating element from becoming wet.

[0013] As an aspect of the present invention, the rear end of the slope portion and the front end of the opening suppression portion may be disposed at substantially the same position in the vehicle front-rear direction. According to this invention, the opening area of the hole can be minimized while preventing the water from getting in.

[0014] As an aspect of the present invention, a connecting wall portion that connects the slope portion and the opening suppression portion may be provided on both sides of the hole in the vehicle width direction. With this invention, the connecting wall portion can block water or muddy water from entering from both sides of the hole in the vehicle width direction, and the connecting wall portion also guides the wind from under the floor, allowing for even better cooling of the heat-generating element.

[0015] As an aspect of the present invention, the opening suppression portion may be inclined upward toward the front of the vehicle. According to this invention, the opening prevention portion having the above-mentioned inclined structure can block the intrusion path of water and muddy water.

[0016] As an aspect of the present invention, the slope portion may be formed in a shape that widens toward the rear of the vehicle in a plan view. According to this invention, the area where the hole is provided can be minimized, and a structure that does not impede the under-cover function can be achieved, while still ensuring an air guide shape that more effectively cools the heat generating element.

[0017] In one aspect of the present invention, wall portions may be provided on the sides of the hole and on both sides of the heating element in the vehicle width direction, and the wall portions may be provided in the longitudinal region where the slope portion is provided. With this invention, when the vehicle is running normally, the wall portion prevents the wind (hot air) from the fan from being directed toward the heat-generating element, and the underfloor running wind (cooling air) guided from the hole along the underside of the slope portion can be concentrated toward the heat-generating element. [Effects of the Invention]

[0018] According to this invention, when the vehicle is running normally, hot air from the fan is prevented from being directed onto the top of the heat-generating element, and the heat-generating element can be cooled down to its upper surface by the airflow from under the floor.On the other hand, when the vehicle is stopped, the air from the fan can be directed onto the heat-generating element even if there is no airflow from under the floor, so that the heat-generating element can be cooled. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. [Figure 2] Cross-sectional view taken along line AA in Figure 1. [Figure 3] FIG. 2 is a cross-sectional view of a main part taken along line BB in FIG. 1 . [Figure 4] FIG. 2 is a cross-sectional view of a main part taken along line CC in FIG. 1 . [Figure 5] A cross-sectional view of the left side of the vehicle along line DD in Figure 1. [Figure 6] FIG. 2 is a bottom view of the main part of the vehicle undercarriage with the undercover removed. [Figure 7] FIG. 4 is a top perspective view showing the undercover structure in the vicinity of the heat generating element. [Figure 8] 5 is an explanatory diagram illustrating the flow of underfloor running air and hot air relative to the heating element; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] a heat generating element provided below a floor panel of the vehicle, an undercover fixed to the vehicle body and provided below the heat generating element, and a fan that cools a heat source member and generates a rearward-flowing airflow in a space between the undercover and the floor panel in front of the heat generating element, for the purposes of preventing hot air from the fan from being directed toward an upper part of a heat generating element during normal vehicle driving, and allowing the heat generating element to be cooled up to its upper surface by underfloor airflow while the vehicle is stopped, even without underfloor airflow; the undercover has a hole that introduces airflow from under the heat generating element from a position forward of the heat generating element when the vehicle is running, and a slope that slopes upward from the front end of the hole toward the rear, and a wall member that is provided in a vehicle longitudinal direction region where the sloped portion is provided, the wall member being provided so as to overlap with an upper part of the heat generating element in a front view of the vehicle, and a space portion that allows an inflow of air from the fan between the upper end of the sloped portion and the lower end of the wall member The upper end of the slope portion and the center of the heating element in the vehicle vertical direction overlap in a front view of the vehicle, and the slope portion is located on an extension line of the wall member in a side view of the vehicle. This was realized by the following configuration. [Example]

[0021] An embodiment of the present invention will be described in detail below with reference to the drawings. The drawings show the undercarriage of a vehicle, with Figure 1 being a bottom view showing the undercarriage of the vehicle, Figure 2 being a cross-sectional view taken along line AA in Figure 1, Figure 3 being a cross-sectional view of a key part taken along line BB in Figure 1, Figure 4 being a cross-sectional view of a key part taken along line CC in Figure 1, and Figure 5 being a cross-sectional view of the left side of the vehicle taken along line DD in Figure 1.

[0022] 6 is a bottom view of the main part showing the undercarriage of the vehicle with the undercover removed, and FIG. 7 is a top perspective view showing the undercover structure in the vicinity of the heating element. This invention can also be applied to electric vehicles, but in the following embodiments, we will explain the structure adopted in a vehicle with an engine mounted at the front of the vehicle that drives the rear wheels, i.e., a front engine rear wheel drive (FR) type vehicle.

[0023] As shown in Fig. 2, a dash lower panel 3 (dash panel) is provided to separate an engine compartment 1 from a passenger compartment 2 in the longitudinal direction of the vehicle. A dash cross member 4 is joined and fixed to the lower front part of the dash lower panel 3, and a cowl reinforcement 5 is joined and fixed to the upper front part of the dash lower panel 3. A dash cross closed section 6 extending in the vehicle width direction is formed between the front surface of the dash lower panel 3 and the dash cross member 4.

[0024] The dash lower panel 3 described above is spanned between a pair of left and right hinge pillars 7, 7 extending in the vertical direction of the vehicle, and is provided with a pair of left and right front side frames 8, 8 extending forward of the vehicle from the dash lower panel 3. A pair of left and right apron reinforcements 9, which are vehicle body strength members, are provided above each of the front side frames 8 and on the outer sides in the vehicle width direction.

[0025] A suspension housing 10 is provided between the apron reinforcement 9 located above and the front side frame 8 located below. The front end of the apron reinforcement 9 and the front end of the front side frame 8 are connected in the vertical direction by a connecting member 11. A heat exchanger unit 12 for cooling the engine air is disposed at the front end of the engine compartment 1.

[0026] The heat exchanger unit 12 includes a radiator 13 as a heat source member, a radiator fan 14 as a fan, and a radiator cowling 15. The radiator 13 is a heat exchanger that uses wind generated by running the vehicle and wind from the radiator fan 14 to air-cool engine coolant. The radiator fan 14 is provided at the rear of the radiator 13, and is a fan that cools the radiator 13 as a heat source member in front of a DC-DC converter 42 as a heat generating element, which will be described later, and generates wind that flows rearward in a space 53 (see FIG. 2) between undercovers 49 to 52 and the front floor panel 16.

[0027] Meanwhile, a front floor panel 16 serving as a floor panel is provided at the lower rear end of the dash lower panel 3. This front floor panel 16 extends rearward from the lower rear end of the dash lower panel 3, and forms the floor surface of the passenger compartment 2. A tunnel portion 17 that extends in the longitudinal direction of the vehicle and protrudes toward the passenger compartment 2 is formed integrally or integrally with the front floor panel 16 at the center of the vehicle width direction, as shown in Figures 1 and 5 .

[0028] As shown in Figures 2 and 5, a tunnel side frame 18 extending in the fore-and-aft direction of the vehicle is provided at the corner between the lower end of the tunnel section 17 and the inner end of the front floor panel 16 in the vehicle width direction, and a tunnel side closed cross section 19 extending in the fore-and-aft direction of the vehicle is formed between the corner and the tunnel side frame 18.

[0029] 3 and 4, an upwardly rising bent portion 16a is integrally formed at the rear end of the front floor panel 16, and a kick-up member 20 is attached to this bent portion 16a. This kick-up member 20 has a kick-up portion 20a that extends in the vertical direction and a rearward extending portion 20b that extends rearward from the upper end of the kick-up portion 20a.

[0030] A cross member 21 (so-called No. 3 cross member) is joined and fixed between the lower end of the kick-up portion 20a and the rearward extension portion 20b of the kick-up member 20, and a cross member closed cross section 22 extending in the vehicle width direction is formed between the kick-up member 20 and the cross member 21.

[0031] 2, seat mounting brackets 23, 24 are provided at a distance in the front-to-rear direction in the vehicle front-to-rear direction intermediate portion of the front floor panel 16. A cross member 25 (a so-called No. 2.5 cross member) extending in the vehicle width direction is joined and fixed to the upper portion of the front floor panel 16 in the vehicle front-to-rear direction intermediate portion between the seat mounting bracket 24 on the vehicle rear side of the seat mounting brackets 23, 24 and the kick-up portion 20a of the kick-up member 20.

[0032] As shown in Figures 3, 4, and 5, a cross-member closed cross section 26 extending in the vehicle width direction is formed between the above-mentioned cross member 25 and the front floor panel 16, and is configured to improve the rigidity of the lower body.

[0033] 1 to 5, side sills 27, which serve as vehicle body rigidity members extending in the longitudinal direction of the vehicle, are provided on both left and right ends in the vehicle width direction of the front floor panel 16. The side sills 27 are formed by joining a side sill outer 28 shown in Fig. 1 with a side sill inner 29 shown in Figs. 2 to 5, and have a side sill closed cross section extending in the longitudinal direction of the vehicle.

[0034] As shown in Fig. 5, the side sill inner panel 29 includes an inner wall 29a located on the inside in the vehicle width direction, an upper wall 29b and a lower wall 29c extending outward in the vehicle width direction from both upper and lower end portions of the inner wall 29a, an upper joint flange portion 29d extending upward from the outer end of the upper wall 29b in the vehicle width direction, and a lower joint flange portion 29e extending downward from the outer end of the lower wall 29c in the vehicle width direction. For ease of explanation, an area E29 of the side sill inner panel 29 in the vehicle up-down direction is indicated by an arrow in Figs. 5 and 4. Also, as shown in Fig. 5, a joint member 30 is provided in the middle portion of the side sill inner panel 29 in the vehicle front-rear direction.

[0035] As shown in Figure 5, a seat mounting bracket 31 is provided straddling the upper inner side of the cross member 25 in the vehicle width direction and the skirt portion of the tunnel portion 17, and a seat mounting bracket 32 is provided straddling the upper outer side of the cross member 25 in the vehicle width direction and the upper wall 29b of the side sill inner 29.

[0036] As shown in Figures 3 and 5, a floor frame 33 is provided that extends in the fore-and-aft direction of the vehicle, spanning the outer underside of the front floor panel 16 in the vehicle width direction and the inner wall 29a of the side sill inner 29, and a floor frame closed cross section 34 that extends in the fore-and-aft direction of the vehicle is formed between the floor frame 33 and the front floor panel 16.

[0037] The above-mentioned floor frame 33 has a bottom wall 33a, an inner wall 33b and an outer wall 33c rising upward from both inner and outer ends of the bottom wall 33a in the vehicle width direction, and a joining flange portion 33d extending inward in the vehicle width direction from the upper end of the inner wall 33b, and is formed with an approximately U-shaped cross section. As shown in FIG. 5, a joining flange portion 33d of the floor frame 33 is joined and fixed to the underside of the front floor panel 16, and an outer wall 33c of the floor frame 33 is joined and fixed to an inner wall 29a of the side sill inner 29.

[0038] As shown in Figure 1, a pair of left and right front wheels 35, 35 are suspended from the vehicle body via front suspension arms. A front mudguard 36 and a rear mudguard 37 are provided on the front wheel-facing surface of a wheelhouse that surrounds and separates the upper half of the front wheels 35.

[0039] As shown in FIG. 1, a front side under cover 38 having a generally triangular shape in bottom view is provided on the front side of the lower end of the front mudguard 36 and protruding forward of the vehicle. In the drawing, 39 is a rear floor panel and 40 is a rear wheel.

[0040] As shown in FIG. 5, a DC-DC converter (direct current voltage converter) 42 as a heating element is provided below the front floor panel 16 of the vehicle via a heating element support bracket 41.

[0041] 5 and 6, the heating element support bracket 41 has a length in the vehicle width direction that extends between the bracket attachment portion 18a of the tunnel side frame 18 located on the inner side in the vehicle width direction and the bottom wall 33a of the floor frame 33 located on the outer side in the vehicle width direction. The heating element support bracket 41 has attachment portions 41a, 41b for attachment to the vehicle body at both inner and outer ends in the vehicle width direction.

[0042] 5 and 6, an attachment portion 41a on the inner side in the vehicle width direction of the heating element support bracket 41 is fixed to the bracket attachment portion 18a of the tunnel side frame 18 using fastening members such as bolts 43 and nuts. An attachment portion 41b on the outer side in the vehicle width direction of the heating element support bracket 41 is fixed to the bottom wall 33a of the floor frame 33 using fastening members such as bolts 44 and nuts 45.

[0043] As shown in FIGS. 2, 3 and 4, the heating element support bracket 41 is provided below the front floor panel 16 so as to be positioned between the cross member 25 and the kick-up member 20. A DC-DC converter 42 serving as a heating element is attached to the bracket body 41c of the heating element support bracket 41 using a plurality of sets of fastening members 46 such as bolts and nuts.

[0044] As shown in FIGS. 1 and 2, a plurality of undercovers 47 to 52 are provided under the vehicle body. The under cover 47 covers the area from directly below the heat exchanger unit 12 to below the middle part of the engine room 1 in the fore-and-aft direction of the vehicle, and in the width direction of the vehicle, the front part of the cover covers the area between the front side under covers 38, 38, and the rear part of the cover is a front under cover that covers the area between the front side frames 8, 8.

[0045] The under cover 48 is an intermediate under cover that covers the area from the lower middle part of the engine compartment 1 to the lower part of the dash lower panel 3 in the longitudinal direction of the vehicle, and in the width direction of the vehicle, the front part of the cover covers the area between the front side frames 8, 8, and the rear part of the cover covers the area between the rear mudguards 37, 37.

[0046] The undercover 49 is a first undercover that covers from the lower portion of the dash lower panel 3 to the lower middle portion of the front floor panel 16 in the fore-and-aft direction of the vehicle, and in the width direction of the vehicle, covers from the lower middle portion of the tunnel portion 17 in the width direction of the vehicle to the lower portion of the side sill inner 29 on the left side of the vehicle.

[0047] The under cover 50 is a second under cover that covers from the lower middle part of the front floor panel 16 to the lower rear part of the rear floor panel 39 in the vehicle longitudinal direction, and from the lower part of the tunnel side frame 18 to the lower part of the side sill inner 29 on the left side of the vehicle in the vehicle width direction.

[0048] The under cover 51 is a third under cover that covers from the lower portion of the dash lower panel 3 to the lower middle portion of the front floor panel 16 in the fore-and-aft direction of the vehicle, and in the width direction of the vehicle, covers from the lower middle portion of the tunnel portion 17 in the width direction of the vehicle to the lower portion of the side sill inner 29 on the right side of the vehicle.

[0049] The under cover 52 is a fourth under cover that covers from the lower middle part of the front floor panel 16 to the lower rear part of the rear floor panel 39 in the vehicle longitudinal direction, and from the lower part of the tunnel side frame 18 to the lower part of the side sill inner 29 on the right side of the vehicle in the vehicle width direction.

[0050] As shown in FIGS. 1 and 2, the undersides of the under-covers 47 to 52 are formed to be substantially flat, and the under-covers 47 to 52 are fixed to the vehicle body. 2, the second undercover 50 of the undercovers 47 to 52 is provided below the DC-DC converter 42, which is a heat generating element. In addition, a space 53 is formed between the first to fourth undercovers 49 to 52 and the front floor panel 16, for allowing the radiator fan 14 and wind generated by the vehicle traveling to flow rearward.

[0051] That is, in this embodiment, a radiator fan 14 is provided in front of the DC-DC converter 42 of the vehicle as a fan that cools the radiator 13 and generates rearward airflow in the space 53 between the undercovers 49 to 52 and the front floor panel 16. Of the above-mentioned first to fourth under-covers 49 to 52, the second under-cover 50 is configured as shown in FIGS.

[0052] That is, the second under-cover 50 includes an under-cover main body 50a whose lower surface is formed in a substantially flat shape, a vertical wall portion 50b that rises upward from the outer end of the under-cover main body 50a in the vehicle width direction and extends in the vehicle front-rear direction, and an upper wall portion 50c that extends outward in the vehicle width direction from the upper end of the vertical wall portion 50b. For ease of explanation, in Figures 3 and 4, an area E50 of the second under-cover 50 in the vehicle up-down direction is indicated by an arrow.

[0053] In addition, the undercover main body 50a of the second undercover 50 described above is integrally formed with a plurality of ribs 50d that rise upward from the undercover main body 50a and extend in any direction, thereby improving the rigidity of the second undercover 50. Furthermore, as shown in FIGS. 1 and 7, an opening 50e is formed in the front part of the under-cover body 50a of the second under-cover 50 and at a position close to the tunnel portion 17.

[0054] As shown in Fig. 4, the second under-cover 50 has a hole 54 formed therein that introduces, while the vehicle is running, running wind under the second under-cover 50, i.e., underfloor running wind e1 (see Fig. 8), from a position forward of the DC-DC converter 42, which is a heat-generating element. For ease of explanation, an area E54 of the hole 54 in the fore-and-aft direction of the vehicle is indicated by an arrow in Fig. 4.

[0055] The second under-cover 50 is provided with a sloped portion 55 that slopes upward toward the rear from the front end 54a of the hole 54. In this embodiment, the sloped portion 55 has an inclination angle of 25 degrees, but the value of the inclination angle is not limited to this.

[0056] Furthermore, in the vehicle longitudinal direction region where the above-mentioned slope portion 55 is provided (i.e., within the longitudinal range of the slope portion 55), a wall member 56 is provided that overlaps with the upper part of the DC-DC converter 42 when viewed from the front of the vehicle.

[0057] In this embodiment, the wall member 56 is formed in an inclined shape so as to slope downward toward the front from the front end of the bracket body 41c of the heat generating element support bracket 41. In other words, the wall member 56 is formed integrally with the heat generating element support bracket 41.

[0058] Here, the wall member 56 is formed with a low front and high rear shape at an inclination angle of approximately 60 degrees relative to the bracket body 41c of the heat generating element support bracket 41, but is not limited to this numerical value of the inclination angle. As shown in FIG. 5, the wall member 56 is provided so as to overlap substantially the entire upper portion of the DC-DC converter 42 in the vehicle width direction when viewed from the front of the vehicle.

[0059] Furthermore, as shown in FIG. 4, a space 57 that allows the inflow of wind from the radiator fan 14 is provided between the upper inclined end of the slope portion 55 and the lower inclined end of the wall member 56.

[0060] In short, the second under-cover 50 described above has a hole 54 that introduces the wind generated by running underneath the second under-cover 50 from a position forward of the DC-DC converter 42 when the vehicle is running, and a slope 55 that slopes upward from a front end 54a of the hole 54 toward the rear, and is provided with a wall member 56 that is provided in the vehicle longitudinal direction region where the slope 55 is provided, overlapping with the upper part of the DC-DC converter 42 in a front view of the vehicle, and is provided with a space 57 between the upper end of the slope 55 and the lower end of the wall member 56 that allows the inflow of wind from the radiator fan 14.

[0061] As a result, as shown in Figure 8, when the vehicle is running normally, the wall member 56 prevents the wind (hot air) e2 from the radiator fan 14 from being guided to the top of the DC-DC converter 42, and the underfloor running wind e1 is guided from the hole 54 of the second under-cover 50 along the underside of the slope portion 55 to the top of the DC-DC converter 42, thereby cooling not only the bottom surface of the DC-DC converter 42 but also the top surface of the DC-DC converter 42.

[0062] On the other hand, when the vehicle is stopped (in this embodiment, when the engine is idling with no load), the wind from the radiator fan 14 flowing in from the space 57 hits the DC-DC converter 42, so that the DC-DC converter 42 can be cooled even without underfloor running wind e1.

[0063] 4, a water shielding plate 58 is provided as an opening suppressing portion, extending upward from the rear end 54b of the hole 54. In this embodiment, the water shielding plate 58 is formed so as to be inclined upward toward the front of the vehicle.

[0064] Specifically, the water shielding plate portion 58 is inclined at an angle of approximately 25 degrees relative to the under-cover main body 50a of the second under-cover 50 in a front-high, rear-low configuration. The front end of the water shielding plate portion 58 is formed at a position lower than the rear end position of the slope portion 55, and an underfloor traveling wind introduction hole 59 is formed between the rear end of the slope portion 55 and the front end of the water shielding plate portion 58. The value of the inclination angle of the water shielding plate portion 58 is not limited to the exemplified value of 25 degrees.

[0065] In this way, by providing a water shielding plate portion 58 as an opening suppression portion extending upward from the rear end portion 54b of the above-mentioned hole portion 54, the water shielding plate portion 58 is configured to suppress the intrusion of water kicked up from the road surface by the front wheel 35 shown in Figure 1 and moisture e3 contained in muddy water (see Figure 8) from the above-mentioned hole portion 54 into the DC-DC converter 42 side, thereby suppressing the DC-DC converter 42 from being wetted.

[0066] Moreover, the water blocking plate portion 58 is configured to be inclined upward toward the front of the vehicle, thereby blocking the intrusion path of water and muddy water. 4, the inclined rear end of the slope portion 55 and the inclined front end of the water shielding plate portion 58 are disposed at approximately the same position in the vehicle front-rear direction. This minimizes the opening area of the hole 54 while suppressing water from reaching the DC-DC converter 42.

[0067] Furthermore, as shown in FIGS. 3 and 7, connecting walls 60, 61 that connect the slope portion 55 and the water shielding plate portion 58 are provided on both the left and right sides of the hole portion 54 in the vehicle width direction.

[0068] The connecting wall portion 60 on the slope portion 55 side is formed in the shape of a right triangle when viewed from the side of the vehicle, with its base connected to the undercover main body 50a at the front edge of the hole portion 54, its hypotenuse connected to the vehicle width direction end of the slope portion 55, and its opposite side connected to the opposite side of the connecting wall portion 61 on the water barrier plate portion 58 side.

[0069] The connecting wall portion 61 on the water shielding plate portion 58 side is formed in the shape of a right triangle when viewed from the side of the vehicle, with its base connected to the undercover main body 50a at the rear edge of the hole portion 54, its hypotenuse connected to the vehicle width direction end of the water shielding plate portion 58, and its opposite side connected to the opposite side of the connecting wall portion 60 on the slope portion 55 side.

[0070] As a result, the connecting walls 60, 61 block water and muddy water from entering from both sides of the hole 54 in the vehicle width direction, and the left and right connecting walls 60, 61 guide the underfloor traveling wind e1, thereby cooling the DC-DC converter 42 even more effectively.

[0071] 5 and 7, the slope portion 55 is formed in a shape that widens toward the rear of the vehicle in a plan view of the vehicle. That is, the slope portion 55 is formed so that the dimension in the vehicle width direction at the front end is relatively small and the dimension in the vehicle width direction becomes relatively large toward the rear end.

[0072] This minimizes the area for providing the above-mentioned hole 54, and while the structure does not impede the under-cover function, it is configured to ensure an air guide shape for more effectively cooling the DC-DC converter 42 as a heat-generating element.

[0073] 5 to 7, vertical walls 62 are provided as wall portions on both sides of the hole 54 in the vehicle width direction in front of the DC-DC converter 42. In this embodiment, as shown in Fig. 7, a pair of left and right vertical walls 62, 62 are provided on both left and right sides of the underfloor running-wind introduction hole 59 in the vehicle width direction so as to extend inward and outward in the vehicle width direction from the boundary between the front connecting wall portion 60 and the rear connecting wall portion 61. The vertical wall 62 is provided in the front-rear direction region where the slope portion 55 is provided.

[0074] As a result, when the vehicle is running normally, the above-mentioned vertical wall 62 prevents the wind (hot air) from the radiator fan 14 from being guided to the DC-DC converter 42, and the underfloor running wind (cooling air) e1 (see Figure 8) guided from the hole portion 54 along the underside of the slope portion 55 is concentrated on the above-mentioned DC-DC converter 42.

[0075] FIG. 8 is an explanatory diagram showing the flow of underfloor traveling air e1 and air (hot air) e2 from the radiator fan 14 relative to the DC-DC converter 42 as a heat generating element. The operation of the vehicle undercarriage structure constructed as above will be described below with reference to FIG.

[0076] When the vehicle is running normally, the wind (hot air) e2 from the radiator fan 14 flows from the front of the vehicle to the rear of the vehicle through the space 53, and this wind (hot air) e2 is prevented from being guided to the top of the DC-DC converter 42 by the wall member 56 integrated with the heating element support bracket 41.

[0077] Therefore, the air (hot air) e2 from the radiator fan 14 flows upward and rearward along the wall member 56, and then flows above the heating element support bracket 41 toward the rear of the vehicle. In particular, when towing a boat or the like to the rear of the vehicle via a trailer hitch, the engine load during driving becomes even greater and the wind generated by the radiator fan 14 becomes hot air. Therefore, by using the wall member 56 to divert the hot air e2 above the heating element support bracket 41, the thermal impact on the DC-DC converter 42 can be reduced.

[0078] During normal vehicle driving as described above, underfloor traveling wind e1 is generated, and this underfloor traveling wind e1 is introduced from hole 54 of second under-cover 50 through the underside of slope portion 55 and underfloor traveling wind introduction hole 59 into the arrangement space of DC-DC converter 42.

[0079] The underfloor traveling airflow e1 introduced from the underfloor traveling airflow introduction hole 59 into the space in which the DC-DC converter 42 is arranged is divided into air flowing above the DC-DC converter 42 and air flowing below the DC-DC converter 42, as shown by the arrows in Figure 8, thereby enabling the DC-DC converter 42 to be cooled from its lower surface to its upper surface.

[0080] On the other hand, when the vehicle is stopped, no underfloor traveling wind e1 is generated. When the vehicle is stopped, the wind from radiator fan 14 hits DC-DC converter 42 through space 53 between under-covers 49 to 52 and front floor panel 16, and through space 57 between the upper end of slope portion 55 and the lower end of wall member 56, thereby cooling DC-DC converter 42.

[0081] When the front wheels 35 kick up water or moisture e3 contained in muddy water from the road surface while the vehicle is running as described above, the water or moisture e3 flows rearward along the underside of the second under-cover 50 together with the underfloor traveling wind e1, but the water or moisture e3 flowing rearward and upward from the area where the hole 54 is formed hits the water shielding plate 58 once, as shown by the arrow in Figure 8, and then bounces off the water shielding plate 58 downward. This makes it possible to prevent the DC-DC converter 42 from being exposed to water.

[0082] In the figure, arrow F indicates the front of the vehicle, arrow R indicates the rear of the vehicle, arrow IN indicates the inside in the vehicle width direction, arrow OUT indicates the outside in the vehicle width direction, and arrow UP indicates the top of the vehicle.

[0083] As described above, the vehicle undercarriage according to the above embodiment is a vehicle undercarriage comprising: a heating element (DC-DC converter 42) provided below a floor panel (front floor panel 16) of the vehicle; an undercover (second undercover 50) fixed to the vehicle body and provided below the heating element (DC-DC converter 42); and a fan (radiator fan 14) in front of the heating element (DC-DC converter 42) that cools a heat source member (radiator 13) and generates a rearward airflow in a space 53 between the undercover (second undercover 50) and the floor panel (front floor panel 16). The second under-cover 50) has a hole 54 that introduces airflow from under the under-cover (second under-cover 50) from a position forward of the heat generating element (DC-DC converter 42) when the vehicle is moving, and a slope 55 that slopes upward from a front end 54a of the hole 54 toward the rear, and is provided with a wall member 56 that is provided in the vehicle longitudinal direction region where the slope 55 is provided so as to overlap with an upper portion of the heat generating element (DC-DC converter 42) in a front view of the vehicle, and is provided with a space 57 between the upper end of the slope 55 and the lower end of the wall member 56 that allows airflow from the fan (radiator fan 14) to flow in (see FIGS. 2, 4, and 8).

[0084] With such a vehicle undercarriage structure, when the vehicle is running normally, the wall member 56 prevents the wind (hot air) e2 from the fan (radiator fan 14) from being guided to the top of the heat generating element (DC-DC converter 42), and the underfloor running wind e1 is guided from the hole portion 54 along the underside of the slope portion 55 to the top of the heat generating element (DC-DC converter 42), thereby cooling not only the underside of the heat generating element (DC-DC converter 42) but also the top surface of the heat generating element (DC-DC converter 42).

[0085] On the other hand, when the vehicle is stopped, the wind from the fan (radiator fan 14) flowing in from the space 57 hits the heat generating element (DC-DC converter 42), so that the heat generating element (DC-DC converter 42) can be cooled even without wind from running. The slope portion 55 allows the outside air to be drawn in without disturbing the flow of the underfloor traveling wind e1 due to the viscosity of the air flowing along the underside of the slope portion 55.

[0086] The vehicle undercarriage structure also includes an opening suppression portion (water shielding plate portion 58) extending upward from the rear end portion 54b of the hole portion 54 (see FIG. 4). With such a vehicle undercarriage structure, the opening prevention portion (water barrier portion 58) prevents water kicked up from the road surface by the wheels (front wheels 35) and moisture contained in muddy water from entering through the hole portion 54, thereby preventing the heating element (DC-DC converter 42) from becoming wet.

[0087] Furthermore, in this vehicle undercarriage structure, the rear end of the slope portion 55 and the front end of the opening suppression portion (water shielding plate portion 58) are disposed at approximately the same position in the vehicle front-rear direction (see FIG. 4). According to such a vehicle undercarriage structure, the opening area of the hole 54 can be minimized while preventing the heat generating element (DC-DC converter 42) from being exposed to water.

[0088] Furthermore, in the undercarriage structure of such a vehicle, connecting wall portions 60, 61 are provided on both sides of the hole portion 54 in the vehicle width direction, connecting the slope portion 55 and the opening suppression portion (water barrier portion 58) (see Figures 3 and 7). With such a vehicle undercarriage structure, the connecting walls 60, 61 can block water and muddy water from entering from both sides of the hole 54 in the vehicle width direction, and the connecting walls 60, 61 guide the underfloor running wind e1, thereby allowing the heat-generating element (DC-DC converter 42) to be cooled even more effectively.

[0089] Additionally, in such a vehicle undercarriage structure, the opening suppression portion (water shielding plate portion 58) is inclined upward toward the front of the vehicle (see FIG. 4). According to such a vehicle undercarriage structure, the opening suppressing portion (water blocking plate portion 58) having the above-mentioned inclined structure can block the intrusion path of water and muddy water.

[0090] In addition, in such a vehicle undercarriage structure, the slope portion 55 is formed in a shape that widens toward the rear of the vehicle in a plan view (see FIGS. 5 and 7). According to such a vehicle undercarriage structure, the area for providing the hole 54 can be minimized, and the structure does not impede the function of the under-cover 50, while ensuring an air guide shape for more effectively cooling the heat-generating element (DC-DC converter 42).

[0091] Furthermore, in the undercarriage of such a vehicle, walls (vertical walls 62) are provided on the sides of the hole 54 and on both sides of the heating element (DC-DC converter 42) in the vehicle width direction, and the walls are provided in the fore-and-aft region where the slope portion 55 is provided (see Figure 7).

[0092] With such a vehicle undercarriage structure, during normal vehicle driving, the wall portion (vertical wall 62) prevents the wind (hot air) e2 from the fan (radiator fan 14) from being guided toward the heat generating element (DC-DC converter 42), and the underfloor running wind (cooling air) e1 guided from the hole portion 54 along the underside of the slope portion 55 can be concentrated toward the heat generating element (DC-DC converter 42).

[0093] In the configuration of this invention and the correspondence with the above-mentioned embodiment, The heat source member of the present invention corresponds to the radiator 13 of the embodiment. Similarly, The fan is compatible with radiator fan 14, The floor panel corresponds to the front floor panel 16, The heating element corresponds to a DC-DC converter 42, The undercover corresponds to the second undercover 50, The opening suppression portion corresponds to the water shielding plate portion 58, The wall portion corresponds to the vertical wall 62, The present invention is not limited to the configurations of the above-described embodiments.

[0094] For example, in the above embodiment, the DC-DC converter 42, which is an electric control part, is used as an example of the heating element, but the heating element may be a differential, which is a drive system part.

[0095] Furthermore, in the above embodiment, the radiator 13, which is an air-cooling element of an internal combustion engine, is exemplified as the heat source member, but when the present invention is applied to an electric vehicle, the heat source member may be a motor. [Industrial Applicability]

[0096] As described above, the present invention is useful for a vehicle undercarriage that includes a heating element provided below a floor panel of the vehicle, an undercover that is fixed to the vehicle body and provided below the heating element, and a fan in front of the heating element that cools a heat source member and generates airflow in a rearward direction in the space between the undercover and the floor panel. [Explanation of symbols]

[0097] 13...Radiator (heat source component) 14...Radiator fan (fan) 16...Front floor panel (floor panel) 42...DC-DC converter (heating element) 50...Second undercover (undercover) 53…Space 54...Hole 55...Slope section 56...Wall components 57…Space part 58...Water shielding plate section (opening prevention section) 60, 61...Connecting wall section 62...Vertical wall (wall section)

Claims

1. a heating element provided below a floor panel of the vehicle; an undercover fixed to the vehicle body and provided below the heating element; a fan in front of the heat generating element that cools a heat source member and generates a rearward airflow in a space between the undercover and the floor panel, The above under cover is a hole portion that introduces airflow from under the undercover from a position forward of the heating element when the vehicle is traveling; a slope portion extending upward from the front end of the hole toward the rear, a wall member provided in a vehicle front-rear direction region where the slope portion is provided, the wall member being provided so as to overlap an upper portion of the heating element in a front view of the vehicle; a space portion that allows airflow from the fan to flow in is provided between an upper end of the slope portion and a lower end of the wall member, an upper end of the slope portion and a central portion of the heating element in the vehicle vertical direction overlap each other in a front view of the vehicle; The slope portion is located on an extension line of the wall member when viewed from the side of the vehicle. Vehicle undercarriage.

2. an opening suppression portion extending upward from the rear end of the hole portion; The vehicle undercarriage according to claim 1 .

3. The rear end of the slope portion and the front end of the opening suppression portion are disposed at approximately the same position in the vehicle front-rear direction. The vehicle undercarriage according to claim 2.

4. a connecting wall portion that connects the slope portion and the opening suppression portion on both sides of the hole in the vehicle width direction; 4. The vehicle undercarriage structure according to claim 2 or 3.

5. The opening suppression portion is inclined upward toward the front of the vehicle. The vehicle underbody structure according to any one of claims 2 to 4.

6. The slope section is formed in a shape that widens towards the rear of the vehicle when viewed from above. The vehicle underbody structure according to any one of claims 1 to 5.

7. Wall portions are provided on the sides of the hole and on both sides of the heating element in the vehicle width direction, and the wall portions are provided in a front-rear direction region where the slope portion is provided. The vehicle underbody structure according to any one of claims 1 to 6.

Images