BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to a vehicle substructure.

2. Description of Related Art

[0002] Heretofore, a structure that discharges high temperature air behind a radiator or in an engine room to the outside of a vehicle has been proposed. Japanese Patent Application Publication No. 2006-347385 (JP 2006-347385 A) discloses a technique in which a duct is disposed behind a radiator disposed in a vehicle front part and high temperature air from the radiator is sent to an opening part disposed to an undercover and discharged outside of a vehicle. '

[0003] However, according to a structure of JP 2006-347385 A, the high temperature air discharged from the duct collides with air that flows along an underfloor part of a vehicle and an air current is disturbed in the underfloor part of a vehicle.

SUMMARY OF THE INVENTION

[0004] The present invention provides a vehicle substructure in which stability of an air current under a floor of a vehicle is improved.

[0005] A vehicle substructure according to embodiments of the present invention includes an opening part opened from a vehicle lower side to the outside of the vehicle, and a guide part that has a guide surface that inclines toward a vehicle rear lower side, has an angle formed with a vehicle base that becomes smaller from a vehicle front side toward a rear side, and guides air in the vehicle to the opening part.

[0006] According to the vehicle substructure having the structure described above, the guide surface of the guide part that guides air in a vehicle to the opening part inclines toward a vehicle rear lower side and has an angle formed with a horizontal direction that becomes smaller from a vehicle front side toward a rear side. Therefore, the air in the vehicle proceeds toward a vehicle rear lower side and, as approaching the opening part, is guided in a direction near a horizontal direction and discharged from the opening.

[0007] According to the vehicle substructure having the structure described above, the stability of an air current under the floor of a vehicle can be improved by smoothly converging air that is discharged from the opening part and air that flows under the floor of a vehicle. ·

[0008] The vehicle substructure according to the embodiments of the present invention may include the guide surface that has a lower side guide surface that guides air from the inside of the vehicle to the opening part after the air passed through a lower side of the guide part, and an upper side guide surface that guides air from the inside of the vehicle to a rear side than the lower side guide surface of the opening after the air passed through an upper side of the guide part.

[0009] According to the vehicle substructure of the structure described above, the air passes a lower side and an upper side of the guide part and flows to the opening. Due to the pressure difference between the upper and lower side at that time, a down force can be generated.

[0010] The vehicle substructure having the structure described above can improve the stability of vehicle travel by generating the down force by an air current that passes the guide part.

[0011] The vehicle substructure according to the embodiments of the present invention may include a folded back part that inclines upwardly in a vehicle rear at a rear lower end of the guide part.

[0012] According to the vehicle substructure of the structure described above, air guided to the opening part along the guide surface and a flow under the floor of a vehicle are directed rear upward at the folded back part. Therefore, air discharged from the opening part flows along a floor surface of a vehicle.

[0013] According to the vehicle substructure having the structure described above, since the air discharged from the opening part and a flow under the floor of a vehicle are directed rear upward at the folded back part and flow along a floor surface of a vehicle, the air discharged from the opening part and air that flows under the floor of a vehicle are more smoothly converged, and the stability of the air current under the floor of a vehicle can be improved thereby.

[0014] The vehicle substructure according to the embodiments of the present invention is disposed along an underfloor part of a vehicle and may include an installation part that is installed to the underfloor part of the vehicle and joint parts that are formed at both ends in a vehicle width direction of the guide part and join the installation part and the guide part. '

[0015] According to the vehicle substructure having the structure described above, the guide part can be stably installed to the underfloor part of a vehicle via the installation part.

[0016] Since the vehicle substructure having the structure described above has the joint part and the installation part, the guide part can be stably installed to the underfloor part.

[0017] The vehicle substructure according to the embodiments of the present invention may have a vehicle front side of the installation part installed to a suspension member on a vehicle front side and a vehicle rear side of the installation part installed to the underfloor part of the vehicle.

[0018] According to the vehicle substructure having the structure described above, since the suspension member in the vehicle front side and the underfloor part of the vehicle are joined by the installation part, a force that moves the suspension member in a vehicle width direction during turning of a vehicle and the like can be supported' by the underfloor part of a vehicle. Therefore, the steering stability can be improved.

[0019] The vehicle substructure having the structure described above can improve the steering stability.

[0020] The vehicle substructure according to the embodiments of the present invention may have a plurality of the guide parts disposed so as to line up in a vehicle longitudinal direction, and lower ends of the guide parts on the vehicle rear side, which are disposed on a vehicle upper side than lower ends of the guide parts on the vehicle front side.

[0021] According to the vehicle substructure having the structure described above, since, in the guide parts that are plurally lined-up, lower ends of the guide parts on the vehicle rear side are disposed on a vehicle upper side than lower ends of the guide parts on the vehicle front side, the air that is guided along the guide parts on the vehicle front side and discharged from the opening part and the air that is guided along the guide parts on the vehicle rear side and discharged from the opening part can smoothly be converged.

[0022] The vehicle substructure having the structure described above can smoothly converge the air that is guided along the guide parts on the vehicle front side and discharged from the opening part and the air that is guided along the guide parts on the vehicle rear side and discharged from the opening part. Therefore, the stability of the air current under the floor of a vehicle can be improved.

[0023] The vehicle substructure according to the embodiments of the present invention may have the opening part disposed in a vehicle lower side of an engine room.

[0024] According to the vehicle substructure having the structure described above, the air that flows to a vehicle lower side from the inside of the engine room proceeds to a vehicle rear lower side by the guide part and discharged from the opening part. Therefore, an dir current under a floor can be suppressed from being disturbed.

[0025] The vehicle substructure having the structure described above . can suppress the air current under the floor from being disturbed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a bottom view that shows a vehicle substructure according to a first embodiment; FIG. 2 is a perspective view that shows a rectification member according to the first embodiment and an installation position thereof;

FIG. 3 is a side cross-sectional view of the rectification member according to the first embodiment;

FIG. 4 is a perspective view that shows a rectification member according to a modification example of the first embodiment;

FIG. 5 is a perspective view that shows a rectification member according to another modification example of the first embodiment;

. FIG. 6 is a perspective view that shows a rectification member according to a second embodiment;

FIG. 7 is a side cross-sectional view of the rectification member according to the second embodiment;

FIG. 8A is a perspective view that shows a rectification member according to a third embodiment, and FIG. 8B is a bottom view thereof;

FIG. 9 is a side cross-sectional view of a rectification member according to a third embodiment;

FIG. 10 is a perspective view that shows a rectification member according to a fourth embodiment;

FIG. 11 is a side cross-sectional view of the rectification member according to the fourth embodiment;

FIG. 12A is a perspective view that shows a rectification member according to a fifth embodiment, FIG. 12B is a side cross-sectional view thereof, and FIG. 12C is a side cross-sectional view of a modification example of a rear guide piece;

FIG. 13 is a bottom view that shows a vehicle substructure showing a variation of an installation position of the rectification member;

FIG. 14 is a bottom view that shows a vehicle substructure according to a sixth embodiment;

FIG. 15 is a side cross-sectional view of a rectification member according to the sixth embodiment; FIG. 16 is a cross-sectional view that shows an installation state of the rectification member and a floor under member according to the sixth embodiment;

FIG. 17 is a bottom view that shows a vehicle substructure according to a modification example 1 of the sixth embodiment; and

FIG. 18 is a bottom view that shows a vehicle substructure according to a modification example 2 of the sixth embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0027] Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. For the sake of description convenience, in the respective drawings, optionally shown arrow marks UP, FR and W respectively show a vehicle upper direction, a vehicle forward direction and a vehicle width direction.

[0028] <First Embodiment Firstly, a vehicle substructure 10 according to a first embodiment will be described. As shown in FIG. 1, on a lower front side of a vehicle, a front undercover 12 is disposed. The front undercover 12 is extended from a front end of the vehicle to a rear side of front wheels 11 so as to cover a lower side of an. engine room (not shown in the drawing) of the vehicle and forms a bottom of the vehicle.

[0029] In the rear side of the front undercover 12, a floor panel 14 that forms a part of a vehicle body is disposed. The floor panel 14 is formed into a plate, and, at a center in a vehicle width direction, a tunnel part 14A is formed in a concave configuration to a lower direction of a vehicle. The tunnel part 14A is provided with an exhaust system 16 such as an exhaust tube and a catalyst converter. The engine room is open to the tunnel part 14A.

[0030] As shown in FIG. 2, on a lower side of a front end of the tunnel part 14A, a rectification member 20 is disposed. The rectification member 20 includes an installation part 22, joint parts 26 and a guide part 30.

[0031] The installation part 22 is formed into a rectangular plate frame, and inside of the frame, a front opening part 24 that is a rectangular opening is formed. Both ends in a longitudinal direction of the installation part 22 are taken as short side parts 22A, a vehicle front side among both end parts in a short-dimension direction is taken as a front long side part 22B, and a vehicle rear side is taken as a rear long side part 22C. The installation part 22 is disposed such that the short side parts 22 A run along a vehicle longitudinal direction. Each of the short side parts 22A is provided with installation holes 22H. Two installation holes 22H are formed for each of the short side parts 22A so as to be aligned in a vehicle longitudinal direction.

[0032] As shown also in FIG. 3, the guide part 30 is formed into a plate shape that curves in a round shape, and a round convex surface side is disposed to be directed downward. A surface on the convex side of the guide part 30 is called hereinafter as "a lower side guide surface 32" and a surface on the concave side is called hereinafter as "an upper side guide surface 34". The lower side guide surface 32 and the upper side guide surface 34 incline towards the vehicle rear lower side, and an angle formed with a lower surface of the floor panel 14 (an angle formed with a horizontal direction) is formed into a round shape that becomes gradually smaller from a vehicle front side to a vehicle rear side. The guide part 30 has a rear end side that is integrally formed with the rear long side part 22C.

[0033] The joint parts 26 are formed at both ends in a longitudinal direction of the front opening part 24. The joint part 26 is formed into a plate, a plate surface is disposed along a short-dimension direction of the front opening part 24, and is formed in a standing manner in the installation part 22. An upper side end of the joint part 26 is formed into a round shape along a side end surface of the guide part 30. The joint part 26 joins an end part in a vehicle width direction and the installation part 22 of the guide part 30.

[0034] The guide part 30 and the joint parts 26 are disposed in the tunnel part 14A and the installation parts 22 are fixed to a lower surface of the floor panel 14. The rectification member 20 is fixed to the floor panel 14 by inserting bolts 27 into the installation holes 22H and fixing with nuts 28.

[0035] On the vehicle front side of the guide part 30 and the joint parts 26, an inlet port 36 that is open to the inside of a vehicle and allows air in a vehicle to flow in. The air flowed to the inlet port 36 flows along a lower side guide surface 32 and is discharged outside of a vehicle from the front opening part 24.

[0036] A vehicle rear side of the rear long side part 22C forms a rear opening part 25. The rear opening part 25 is opened to the outside of a vehicle, and an air current that flows along an upper side guide surface 34 of the guide part 30 from the inside of a vehicle is discharged from the rear opening part 25.

[0037] The rectification member 20 can be formed from various materials. For example, when formed from iron, aluminum, carbon or the like, stiffness of a vehicle lower part can be improved and can contribute to the steering stability of a vehicle. Further, when formed from resin fiber, noise can be absorbed and the vehicle exterior noise can be made smaller thereby.

[0038] Next, effects of the vehicle substructure of the present embodiment will be described.

[0039] When the vehicle is running, an air current under the floor of a vehicle flows backward, as shown in FIG. 3, along an underfloor part of a vehicle (air current Al). On the other hand, when an air current from the inside of a vehicle reached the rectification member 20 by flowing to a vehicle, rear side, an air current A2 that passes a lower side than the guide part 30 flows in an inlet port 36, flows backward along a lower side guide surface 32, and is discharged from the front opening part 24. Further, an air current A3 that passes an upper side than the guide part 30 flows backward along the upper side guide surface 34, is sent backward along the tunnel part 14A and discharged from the rear opening part 25.

[0040] According to the present embodiment, the lower side guide surface 32 and the upper side guide surface 34 of the guide part 30 incline to a vehicle rear lower side and form a round shape such that an angle formed with a lower surface of the floor panel 14 becomes smaller toward a rear side from a vehicle front side. Therefore, the air currents A2 and A3 discharged from the front opening part 24 and the rear opening part 25 are discharged at an angle along the front undercover 12 and a lower surface of the floor panel 14. Thus, the air currents A2 and A3 from the inside of a vehicle and the air current Al that flows under the floor of the vehicle are smoothly converged and the stability of the air current under the floor of the vehicle can be improved.

[0041] Further, according to the present embodiment, since an air current passes both of upper and lower surfaces (lower side guide surface 32 and upper side guide surface 34) of the guide part 30, a down force can be generated and the steering stability of a vehicle can be improved. Further, since one guide part 30 can guide a lot of air, an air amount and an air direction can be more stabilized.

[0042] According to the present embodiment, although a structure in which openings (front opening part 24 and rear opening part 25) are disposed on both sides of each of rear and front sides of a vehicle and an air current passes both of the lower side guide surface 32 and the upper side guide surface 34 was formed, it is not necessarily required to form into the present structure. A structure in which the opening is formed on only one of front and rear sides of the guide part 30 and the air current passes only one surface of the guide part can be formed.

[0043] Further, according to the present embodiment, although the installation part 22 of the rectification member 20 was formed into a frame, the installation part 22 is not necessarily formed into a frame, as shown in FIG. 4, a structure that does not have the front long side part 22B may be formed. By removing the front long side part 22B, mass of the rectification member 20 can be reduced, and also a production cost can be suppressed low thereby. Further, since a dimension of the rectification member 20 in a vehicle longitudinal direction can be made smaller, a freedom at the time of installation to a vehicle can be improved.

[0044] Further, as shown in FIG. 5, in the circumference of the inlet port 36 of the rectification member 20, a frame 37 may be disposed. By disposing the frame 37, when the rectification member 20 is produced by a press process of metal, the inlet port 36 can be readily formed.

[0045] Further, according to the present embodiment, the joint part 26 was disposed. However, the joint part 26 is not necessarily required. By disposing the joint part 26 like the present embodiment, the strength of the guide part 30 can be improved. [0046] Still further, according to the present embodiment, the lower side guide surface 32 and the upper side guide surface 34 were formed into a round shape. However, these surfaces are not necessarily formed into a round shape, that is, a structure in which a plurality of flat planes are arranged such that an angle formed with a lower surface of the floor panel 14 becomes smaller toward a rear side from a vehicle front side can be used.

[0047] <Second Embodiment Next, a second embodiment of the present invention will be described. In the present embodiment, the same reference numerals are imparted to the same parts as the first embodiment, and detailed descriptions thereof are omitted.

[0048] A vehicle substructure of the present embodiment includes a rectification member 40. The rectification member 40 has the same structure as the rectification member 20 of the first embodiment and further includes a front folded-up part 42 and a rear folded-up part 44. An installation position and an installation method of the rectification member 40 to a vehicle are the same as the first embodiment. Further, modification examples and material selection applied to the first embodiment can also be applied similarly to the present embodiment.

[0049] As shown in FIG. 6, the front folded-up part 42 is formed along a front opening part 24 side of a front long side part 22B. The front folded-up part 42 projects so as to incline to a vehicle rear upper side from a front long side part 22B. As shown in FIG. 7, to the front folded-up part 42, an upper surface 42A of a vehicle upper side and a lower surface 42B of a vehicle lower side are provided.

[0050] The rear folded-up part 44 is formed along the front opening part 24 side of the rear long side part 22C. The rear folded-up part 44 projectes so as to incline from the rear long side part 22C to a vehicle rear upper side. An upper surface 44A on a vehicle upper side of the folded-up part 44 and a lower surface 44B on a vehicle lower side are formed.

[0051] Next, effects of the vehicle substructure of the present embodiment will be described. [0052] When the vehicle is running, an air current under the floor of a vehicle flows, as shown in FIG. 7, toward a rear side along an underfloor part of a vehicle (air current Al). Further, an air current from the inside of a vehicle is divided into air currents A2 and A3 and the air currents A2 and A3 are discharged respectively from the front opening part 24 and the rear opening part 25. In the present embodiment, on a vehicle front side of the front opening part 24 the front folded-up part 42 is formed. Therefore, an eddying current Rl that winds up backward in the proximity of the backward side of the front folded-up part 42 is generated. Further,, on a vehicle front side of the rear opening part 25, the rear folded-up part 44 is formed. Therefore, an eddying current R2 that winds up backward in the proximity of the backward of the rear folded-up part 44 is generated. Due to these eddying currents Rl and R2, the air currents Al, A2 and A3 are pulled up upward in the backward. Thus, the air currents A2 and A3 discharged from the front opening part 24 and the rear opening part 25 are suppressed from proceeding downward, and the air currents A2 and A3 can be smoothly converged with the air current Al and the stability of the air current under a floor of a vehicle can be improved.

[0053] <Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. 8 and FIG. 9. In the present embodiment, the same reference numerals are imparted to the same parts as the first and second embodiments, and detailed descriptions thereof are omitted.

[0054] The vehicle substructure of the present embodiment includes a rectification member 50. The rectification member 50 has the same structure as the rectification member 20 of the first embodiment, and, as shown in FIGs. 8A and 8B, further includes rectification projections 52. The installation position and the installation method of the rectification member 50 to a vehicle are the same as the first embodiment. Further, modification examples and material selection applied to the first and second embodiments can also be applied similarly to the present embodiment.

[0055] Three rectification projections 52 are disposed at a rear end of the upper side guide surface 34 of the guide part 30. The three rectification projections 52 are disposed separated by a distance in a vehicle width direction. The rectification ,

. 12

projections 52 are formed such that a longitudinal direction goes along a vehicle longitudinal direction, and as goes from an end part to a center side in a longitudinal direction, a width dimension in a vehicle width direction gradually expands. As shown in FIG. 9, the rectification projection 52 is lowest in a projection height from the upper side guide surface 34 in a vehicle front side end, becomes higher in the projection height as goes toward the center, and further inclines backward from the center part toward a rear lower side.

[0056] Next, effects of the vehicle substructure of the present embodiment will be described.

[0057] During vehicle running, an air current under a floor of a vehicle flows backward along an underfloor part of a vehicle (air current Al). Further, an air current from a front side in a vehicle is divided into air currents A2 and A3, and the air currents A2 and A3 are discharged respectively from the front opening part 24 and the rear opening part 25.

[0058] According to the present embodiment, since the rectification projections

52 are disposed on the upper side guide surface 34, in the air current A3 that is discharged along the upper side guide surface 34, by passing the rectification projections 52, as shown in FIG. 9, an eddying current R3 (vertical vortex) is generated. Due to the eddying current R3, in a rear side from the rear opening part 25, the air currents Al, A2 and A3 are pulled toward a floor surface side of a vehicle. Thus, the air currents Al, A2 and A3 are guided so as to go along an underfloor part of a vehicle and the stability of an air current under the floor of a vehicle can be improved.

[0059] Further, as shown with an arrow mark D of FIG. 8B, the air currents Al, A2 and A3 can be suppressed from expanding outside in a vehicle width direction (an expanded state is indicated with arrow marks W).

[0060] <Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG. 10 and FIG. 11. In the present embodiment, the same parts as the first to third embodiments, and detailed descriptions thereof are omitted. [0061] The vehicle substructure of the present embodiment includes, as shown in FIG. 10, a rectification member 60. The rectification member 60 is formed by arranging three rectification members 20 of the first embodiment in a vehicle longitudinal direction. In the present embodiment, sequentially from the guide part 30 disposed on a vehicle front side, the guide parts are differentiated as guide parts 30A, 30B and 30C. The shapes of the guide parts 30A, 30B and 30C are the same as that of the guide part 30 of the first embodiment.

[0062] The rectification member 60 has an installation part 62. The installation part 62 is formed into a long plate shape extending in a vehicle longitudinal direction, and is disposed on both outsides in a vehicle width direction of the guide parts 30A, 30B and 30C. In the installation part 62, installation holes 62H are formed. On a vehicle front end side of the installation part 62, a front long side part 22B is formed in a vehicle width direction.

[0063] At both ends of the guide part 30A in a vehicle width direction, joint parts 26A are formed. The joint parts 26A have the same structure as that of the joint parts 26 of the first embodiment. In a front side of the guide part 30A and the joint parts 26A, an inlet port 36A that is opened to the inside of the vehicle and allows air in the vehicle to flow in is formed. On a lower side of the guide part 30A, a first front opening part 64A that communicates with outside of the vehicle from the inlet port 36A is formed.

[0064] As shown also in FIG. 11, the guide part 30B has a front upper end 30BF that is disposed on a vehicle upper side of a rear lower end 30AR of the guide part 30A. Further, a rear lower end 30BR is disposed on a vehicle upper side than a rear lower end 30AR of the guide part 30A. As shown in FIG. 10, at both end parts of the guide part 30B in a vehicle width direction, joint parts 26B are formed. The joint parts 26B are erected from the installation part 62 and join the guide part 30B and the installation part 62. The joint part 26B has a lower part longer in a vertical direction than the joint part 26A and an upper side than a rear lower end 30BR has the same shape as the joint part 26A. On a front side of the guide part 30B and the joint parts 26B, the inlet port 36B that is opened to the inside of a vehicle and allows air in the vehicle to flow in is formed. On a lower side of the guide part 30B, a second front opening part 64B that communicates with the outside of the vehicle from the inlet port 36B is formed.

[0065] The guide part 30C has a front upper end 30CF that is disposed on a vehicle upper side position of a rear lower end _\ 30BR of the guide part 30B. Further, a rear lower end 30CR is disposed on a vehicle upper side than a rear lower end 30BR of the guide part 30B. At both end parts of the guide part 30C in a vehicle width direction, joint parts 26C are formed. The joint parts 26C are erected from the installation part 62 and join the guide part 30C and the installation part 62. The joint part 26C has a lower part longer in a vertical direction than the joint part 26A and an. upper side than a rear lower end 30CR has the same shape as the joint part 26A. On a front side of the guide part 30C and the joint parts 26C, the inlet port 36C that is opened to the inside of a vehicle and allows air in the vehicle to flow, in is formed. On a lower side of the guide part 30C, a third front opening part 64C that communicates from the inlet port 36C to the outside of the vehicle is formed, and on a vehicle backward of the guide part 30C, a rear opening part 25 is formed.

[0066] Now, the installation position and an installation method of the rectification member 60 to a vehicle are the same as that of the first embodiment. Further, modification examples and material selection applied to the first to third embodiments can also be applied similarly to the present embodiment. .

[0067] Next, effects of the vehicle substructure of the present embodiment will be described.

[0068] When the vehicle is running, an air current under a floor of a vehicle, as shown in FIG. 11 , flows backward along an underfloor part of a vehicle (air current Al). Further, an air current from the vehicle inside is divided into air currents A4, A5, A6 and A7 and these air currents are discharged respectively from a first front opening part 64A, a second front opening part 64B, a third front opening part 64C and the rear opening part 25. According to the present embodiment, since rear lower ends 30AR, 30BR, and 30CR of the guide parts 30A, 30B and 30C are disposed sequentially on the vehicle upper side as goes backward, the air current discharged from each of the openings and the air current from the front side are suppressed from colliding with each other. Therefore, the air currents Al, A4, A5, A6 and A7 can smoothly be converged and the stability of the air current under the floor of the vehicle can be improved.

[0069] In the present embodiment, an example in which three of the guide parts 30 are arranged was described. However, the guide parts 30 may be two or four or more.

[0070] <Fifth Embodiment Next, a fifth embodiment of the present invention will be described. In the present embodiment, the same reference numerals are imparted to the same parts as the first to fourth embodiments, and detailed descriptions thereof are omitted.

[0071] A vehicle substructure of the present embodiment includes a rectification member 70. As shown in FIG. 12 A, the rectification member 70 has the same structure as the rectification member 20 of the first embodiment and further includes the installation part 22 that is extended further longer vehicle backward than the rear long side part 22C. On a vehicle rear side of the rear long side part 22C, a second opening part 72 is formed in the same manner as the front opening part 24, and on a vehicle rear side of the second opening part 72 a second rear long side part 22D is formed. In an end side on a vehicle front side of the second rear long side part 22D, a rear guide piece 74 is formed along the second opening part 72. As shown also in FIG. 12B, the rear guide piece 74 is formed into a plate that curves in a round shape and projected to a vehicle front upper side from the second rear long side part 22D such that a round shaped convex surface side directs forward and downward. The rear guide piece 74 is disposed in front of a joining member 78 disposed to the tunnel part 14A.

[0072] In the present embodiment, even when the joining member 78 that disturbs a flow of the air current A3 is disposed on a vehicle rear side of the guide part 30, the air current A3 is guided by the rear guide piece 74 and discharged from the inside of a vehicle. Therefore, by smoothly converging with the air current Al that flows under the floor of the vehicle, the stability of the air current under the floor of the vehicle can be improved.

[0073] In the above, the guide piece 74 was formed into a plate that curves in a round shape. However, as shown in FIG. 12C, a flat rear guide piece 76 may be formed. [0074] Further, in the first to fifth embodiments described above, although the rectification member was installed to the floor panel 14 on a lower side of a front end of the tunnel part 14A, it may be installed to other position of an underfloor part of a vehicle. For example, as shown in FIG. 13, it may be installed backward (displayed by a reference numeral 20-R) distanced from the front undercover 12. Further, it may be installed to a lower surface of the front undercover 12 in a front lower side of the engine room (displayed by a reference numeral 20(F)) Or may be installed to a lower surface of the undercover 12 in a lower center part of the engine room (displayed by reference numeral 20(M)). In this case, in order to secure the opening part, an opening OP is formed in the front undercover 12, and the front opening part 24 and the rear opening part 25 are secured thereby.

[0075] Further, in the first to fifth embodiments described above, on the outside in a vehicle width direction of the tunnel part 14A, a tunnel part reinforcement convexed to a vehicle lower direction is disposed, and the rectification member may be installed to an apex of the tunnel part reinforcement. Further, outside in a vehicle width direction of the tunnel part 14A, the undercover may be disposed.

[0076] <Sixth Embodiment Next, a sixth embodiment of the present invention will be described. In the present embodiment, the same reference numerals are imparted to the same parts as the first to fifth embodiments, and detailed descriptions thereof are omitted.

[0077] In FIG. 14 to FIG. 16, the vehicle substructure has a rectification member 80. The rectification member 80 includes the first front opening part 64A and the second front opening part 64B that are an example of the opening part, and the installation part 22. The first front opening part 64A, the second front opening part 64B and the rear opening part 25 are disposed in a vehicle lower direction of the engine room 82. Further, the first front opening part 64A and the second front opening part 64B are disposed in plural in a vehicle width direction. In the illustrated example, two of each of the first front opening part 64A and the second front opening part 64B are disposed bisymmetrically with respect to a center in a vehicle width direction. Two first front opening parts 64 A are distanced from each other in a vehicle width direction. Similarly, two second front opening parts 64B are distanced from each other in a vehicle width direction.

[0078] To the first front opening part 64A and the second front opening part 64B, the guide parts 30A and 30B, and the joint parts 26A and 26B (see FIG. 10) are disposed. As a structure in the proximity of the first front opening part 64A and the second front opening part 64B, without restricting to a structure described in FIG. 15, the structures described in the respective embodiments described above can be optionally applied.

[0079] Under a floor of a vehicle, a floor undermember 84 is disposed. The floor undermember 84 extends in a vehicle longitudinal direction, is joined respectively with both sides in a vehicle width direction of the tunnel part 14A in a lower side of the floor panel 14 and forms a closed cross-section. Further, in a vehicle lower direction of the engine room 82, a suspension member 86 on a vehicle front side is disposed.

[0080] A vehicle front side of the installation part 22 of the rectification member 80 is installed to the suspension member 86 (FIG. 15). Further, a vehicle rear side of the installation part 22 is installed to the floor undermember 84 that is an example of an underfloor member of a vehicle (FIG. 16). The installation part 22 is installed by fixing with a bolt 27 and a nut 28 (FIG. 15, FIG. 16), by clippimg (not shown in the drawing), or the like.

[0081] A shape of the rectification member 80 is different between a front half part 80A and a rear half part 80B. Specifically, while a width of the rear half part 80B (a dimension in a vehicle width direction) is substantially constant, a width of the front half part 80A becomes narrower equally bisymmetrically as goes toward a vehicle front. Therefore, the front long side part 22B of the installation part 22 is shorter than the rear long side part 22C. A boundary between the front half part 80A and the rear half part 80B is set in the proximity of a boundary between the first front opening part 64A and the second front opening part 64B, for example. Accompanying this, the first front opening part 64A is formed into, for example, a near trapezoid, and the second front opening part 64B is formed into, for example, a near rectangle.

[0082] In FIG. 15, in a vehicle upper direction of the first front opening part 64A and the second front opening part 64B, an exhaust system 16 is disposed. In a vehicle upper direction of the exhaust system 16, the floor panel 14 and a dash panel 88 are disposed. The dash panel 88 is a wall that partitions the engine room 82 and, a vehicle chamber 90. A lower end of the dash panel 88 is joined with a front end of the floor panel 14.

[0083] As shown in FIG. 15, an air current under a floor of a vehicle during vehicle running flows backward along an underfloor part of a vehicle (air flow Al). Further air that flows toward a vehicle lower direction from the inside of the engine room 82 proceeds toward a vehicle rear lower side by the guide parts 30A and 30B, is divided into air currents A4, A5 and A7, and these air currents are discharged respectively from the first front opening part 64A, the second front opening part 64B, and the rear opening part 25. Therefore, air currents Al, A4, A5 and A7 can be smoothly converged. As a result, an air current under a floor can be suppressed from being disturbed.

[0084] Further, according to the vehicle substructure, the suspension member 86 and the floor panel 14 (under the floor of vehicle), which are on a vehicle front side are joined by the installation part 22 of the rectification member 80. Therefore, a force that moves the suspension member in a vehicle width direction such as during turning of a vehicle and the like can be supported by the underfloor part of the vehicle. Therefore, the steering stability can be improved.

[0085] Although a vehicle front side of the installation part 22 of the rectification member 80 was installed to the suspension member 86, without restricting to this, the vehicle front side of the installation part 22 may be installed in other site. Further, although the opening parts (the first front opening part 64A, the second front opening part 64B, and the rear opening part 25) were disposed in a vehicle lower direction of the engine room 82, without restricting to this, the opening part may be disposed in a vehicle backward than the engine room 82. A vehicle lower side of the suspension member 86 may be covered further with a separate floor cover (not shown in the drawing).

. [0086] <Modification Example 1> In FIG. 17, on a vehicle rear side of the second front opening part 64B in the rectification member 80, the third front opening part 64C may be disposed. In the illustrated example, a width of the third front opening part 64C in a vehicle width direction is shorter than a width of the second front opening part 64B in a vehicle width direction. Positions of outside ends of the third front opening part 64C in a vehicle width direction are arranged to positions of outside ends in a vehicle width direction of the second front opening part 64B.

[0087] According to the modification example 1, the same as the fifth embodiment, air that flows from the inside of the engine room 82 to a vehicle lower direction is discharged also from the third front opening part 64C and can be smoothly converged with the air current Al of the underfloor part of the vehicle (see air current A6 in FIG. 11).

[0088] <Modification Example 2> In FIG. 18, the front opening part 24 is disposed at a rear end of the rectification member 80, and a vehicle rear side thereof may be made the rear opening part 25. The front opening part 24 is the same as the first embodiment. Two of the front opening parts 24 are bisymmetrically disposed with respect to a center in a vehicle width direction. The two front opening parts 24 are distanced with each other in a vehicle width direction. The front opening part 24 is provided with the guide part, 30 and the joint parts 26 (see FIG. 2). As a structure in the proximity of the front opening part 24, without restricting to the structure described in FIG. 18, structures described in the respective embodiments described above can optionally be used.

[0089] According to the modification example 2, air that flows from the inside of the engine room 82 to a vehicle lower direction, in the same manner as the first embodiment, is discharged from the front opening part 24 and the rear opening part 25 and can smoothly be converged with the air current Al of the underfloor part of the vehicle (see FIG. 3).

[0090] Further, it is also possible that the respective embodiments and the respective modification examples can optionally be combined.