JP5482510B2 - Underfloor structure of the vehicle - Google Patents

Description

  The present invention relates to an under floor structure for a vehicle having a tunnel portion extending in a vehicle front-rear direction along an exhaust system extending in a vehicle front-rear direction at a vehicle width direction central portion behind an engine room.

  Generally, in the under floor portion of a vehicle, a phenomenon occurs in which air that has moved from the engine room to the rear of the vehicle enters the tunnel portion (floor tunnel) when the vehicle is traveling. This air usually has a lower flow velocity than the traveling wind that flows under the under floor when the vehicle is traveling, and therefore causes the following problems.

  Specifically, when the air in the engine room enters the tunnel portion, when the air collides with the traveling wind, a vortex of air is generated at the front portion of the tunnel portion due to a difference in flow velocity between the air and the traveling wind. Occur. The vortex generated in this way causes the aerodynamic performance (CD value) to deteriorate, and as a result, deteriorates the running performance of the vehicle.

  Therefore, in order to improve the running performance of the vehicle, it is conceivable to cover the entire tunnel portion so that the air in the engine room does not interfere with the running wind. However, this is not preferable because the heat in the engine room is trapped in the tunnel, particularly when the vehicle is stopped.

  By the way, what provided the undercover which can open and close the lower part of a tunnel part conventionally is proposed (refer the following patent document 1). In the following Patent Document 1, when the temperature in the tunnel portion is a predetermined high temperature, the under cover is opened to cool the inside of the tunnel portion. On the other hand, when the vehicle speed exceeds a predetermined vehicle speed, the under cover is closed to aerodynamic performance. It is configured to improve.

  Conventionally, there has been proposed one provided with an under cover in which a plurality of slits as heat radiating holes are formed at the lower portion of the tunnel portion and a slide cover for opening and closing the slit (see Patent Document 2 below). In Patent Document 2 below, when the aerodynamic performance is improved by lowering the air resistance of the vehicle, the effective opening area of the slit is reduced, while the temperature rise near the exhaust pipe (in the tunnel portion) is prevented. The inside of the tunnel is cooled by increasing the effective opening area of the slit.

JP-A-4-143175 JP-A-7-215074

  However, none of the conventional techniques disclosed in Patent Documents 1 and 2 discloses suppression of vortices generated at the front part of the tunnel part.

  In the prior arts disclosed in Patent Documents 1 and 2, both cover the lower part of the tunnel part over substantially the entire vehicle longitudinal direction, and open and close the under cover over almost the entire vehicle longitudinal direction. It has a configuration.

  For this reason, when the under cover is closed in order to improve the aerodynamic performance, heat is trapped in the tunnel portion, and in each of the conventional technologies described above, it has been impossible to achieve both aerodynamic performance improvement and cooling performance improvement in the tunnel portion.

  Further, in the conventional techniques disclosed in Patent Documents 1 and 2, since the under cover is opened and closed over substantially the entire vehicle longitudinal direction, not only a driving source having a large driving force is required, The weight of the under floor is also heavy, and it is not always efficient from the viewpoint of cost and vehicle weight.

  An object of the present invention is to provide an underfloor structure for a vehicle that can efficiently improve the aerodynamic performance and the cooling performance in the tunnel portion by suppressing the vortex generated at the front portion of the tunnel portion.

  The underfloor structure of the vehicle according to the present invention is a suspension cross that connects a left and right suspension to a tunnel portion extending in the vehicle front-rear direction along an exhaust system extending in the vehicle front-rear direction at the center in the vehicle width direction behind the engine room. An under floor structure for a vehicle having a member, wherein an under cover for covering a front portion of the tunnel portion is provided at a rear portion of the suspension cross member.

  According to this configuration, the undercover can suppress the air in the engine room from flowing downward between the rear portion of the suspension cross member and the front portion of the tunnel portion, and the air and the front of the vehicle. Interference with the traveling wind can be suppressed. Thereby, it is possible to prevent the vortex from being generated at the front portion of the tunnel portion due to the interference between the traveling wind having a high flow velocity and the air in the engine room having a low flow velocity. Therefore, the turbulence of the air below the under floor portion of the vehicle can be suppressed, and the aerodynamic performance of the vehicle can be improved.

In particular, by providing an under cover at the front part of the tunnel part where the vortex is likely to occur, air turbulence below the under floor part of the vehicle can be obtained without covering the entire lower part of the tunnel part. It can be effectively suppressed.
Here, by disposing the under cover only on the front part of the tunnel part, the rear part of the tunnel part can be always opened. Thereby, the cooling performance in a tunnel part can be improved, covering a tunnel front part efficiently.

  Therefore, the undercover can achieve both aerodynamic performance improvement and cooling performance improvement in the tunnel portion. Furthermore, since it is not necessary to open and close the lower part of the tunnel part, the aerodynamic performance and the cooling performance in the tunnel part can be improved efficiently.

  In one embodiment of the present invention, the under cover is provided with an opening that allows air to move between the lower side of the vehicle body and the engine room.

  According to this configuration, when the vehicle is stopped, air outside the vehicle can be introduced into the engine room and the tunnel part via the opening, and the cooling performance of the engine room and the tunnel part when the vehicle is stopped is improved. Can do.

  In one embodiment of the present invention, the opening is a slit formed so as to extend in the vehicle width direction.

  Since traveling wind during vehicle travel generally flows in the vehicle front-rear direction, when the slit is formed so as to extend in the vehicle front-rear direction along the traveling wind, the traveling wind is generated in the engine room or tunnel portion. However, by forming the slits to extend in the vehicle width direction, it is possible to suppress the flow of the driving wind into the engine room and the tunnel, thereby aerodynamics. Performance can be ensured.

  In one embodiment of the present invention, the front edge of the opening has a shape extending upward.

  According to this configuration, since the front edge portion of the opening portion has a shape extending upward, the opening in which air that is about to flow into the tunnel portion from the engine room extends upward is formed. It is suppressed that it flows into a tunnel part by the front edge part of a part.

  In an embodiment of the present invention, the opening is provided in a position corresponding to the rear portion of the engine room in the under cover.

  According to this configuration, air outside the vehicle can be easily introduced into the engine room when the vehicle is stopped.

  In one embodiment of the present invention, the opening area of the opening is set to about 30% of the entire area of the undercover.

  According to this configuration, aerodynamic performance and cooling performance can be more reliably achieved.

  In one embodiment of the present invention, a substantially flat tunnel reinforcing member is connected to the rear portion of the under cover.

  According to this configuration, the aerodynamic performance can be further improved by the cooperation of the undercover and the tunnel reinforcing member. And the tunnel reinforcement member can also suppress the deformation of the tunnel part due to the vibration of the floor panel or the vehicle collision when the vehicle is running.

  According to this invention, it is possible to suppress the air in the engine room from flowing between the rear portion of the suspension cross member and the front portion of the tunnel portion to the outside below the tunnel portion, and the traveling wind having a high flow velocity, It is possible to prevent the vortex from being generated at the front portion of the tunnel portion due to the interference with the air in the engine room having a low flow velocity. Therefore, the turbulence of the air below the under floor portion of the vehicle can be suppressed, and the aerodynamic performance of the vehicle can be improved.

  In particular, by providing an under cover at the front part of the tunnel part where the vortex is likely to occur, air turbulence below the under floor part of the vehicle can be obtained without covering the entire lower part of the tunnel part. It can be effectively suppressed. And the cooling performance in a tunnel part can be improved, covering a tunnel front part efficiently.

  Therefore, the undercover can achieve both aerodynamic performance improvement and cooling performance improvement in the tunnel portion. Furthermore, since it is not necessary to open and close the lower part of the tunnel part, the aerodynamic performance and the cooling performance in the tunnel part can be improved efficiently.

The bottom view which shows a vehicle provided with the under floor structure which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. The bottom view which shows the principal part of FIG. FIG. 4 is a cross-sectional view taken along line B-B in FIG. 3. Explanatory drawing for demonstrating the flow of the driving | running | working wind at the time of vehicle travel, and the air of an engine room. Explanatory drawing for demonstrating the flow of the external air at the time of a vehicle stop.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a bottom view showing a vehicle V having an under floor structure according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a main portion of FIG. FIG. The vehicle V according to the present embodiment includes a dash panel 1 at the front portion thereof as shown in FIGS. The dash panel 1 is disposed so as to rise from a floor panel 3 that forms the bottom surface of the passenger compartment 2 (see FIG. 2), and partitions the engine room E and the passenger compartment 2 as shown in FIG. In the drawing, the arrow (F) indicates the front of the vehicle body, and the arrow (R) indicates the rear of the vehicle body.

  Further, at the lower part of the vehicle V, the front end portion is connected to the dash panel 1 at the center in the vehicle width direction of the dash panel 1 and the floor panel 3 and from the floor panel 3 toward the vehicle interior 2 on the vehicle body inner side. A protruding tunnel portion (floor tunnel) 4 is provided.

  As shown in FIGS. 1 and 2, the tunnel portion 4 extends in the vehicle front-rear direction along an exhaust system 5 that is disposed behind the engine room E so as to extend in the vehicle width direction center portion in the front-rear direction. .

  As shown in FIGS. 1 and 2, the exhaust system 5 includes an exhaust pipe 6 mainly connected to an exhaust manifold (not shown) that constitutes an exhaust side of the engine, two catalytic converters 7 and 8, a pre-silencer. 9 and the like, and the exhaust system 5 is accommodated in a recessed space of the tunnel portion 4 (hereinafter referred to as the tunnel portion 4).

  Among these, behind the catalytic converter 7 on the front side of the vehicle, a mounting bracket 10 is attached to the exhaust pipe 6 as shown in FIG. 1, and a rubber hanger rubber 11 is attached via the mounting bracket 10. . Further, a rod-like connecting member 12 extending in the vehicle width direction is attached to the exhaust pipe 6 between the catalytic converter 8 and the pre-silencer 9 on the rear side of the vehicle, and the connecting bracket 12 is shown in FIG. A pair of left and right rubber hanger rubbers 13 and 13 are attached. The exhaust system 5 is attached to the tunnel portion 4 via the above-described hanger rubbers 11, 13, and 13 and is elastically supported.

  Although illustration is omitted, in the tunnel part 4, in addition to the exhaust system 5 and the hanger rubbers 11 and 13, for example, a cable for connecting a parking brake and a brake device for wheels, and the cable are covered. A harness or the like that has a tube and a rubber sheath and electrically connects various electrical devices of the vehicle V is routed. Depending on the vehicle model, a change cable for connecting the power train and the change lever arranged in the engine room E and a rubber tube covering the same are routed in the tunnel, as in the FR vehicle. The

  Further, the floor panel 3 is provided with a pair of left and right floor frames 14 and 14 extending in the vehicle front-rear direction, and a front end of the pair of left and right front side frames 15 and 15 extending in the vehicle front-rear direction in the engine room E. Connected to the rear end.

  Further, the floor panel 3 and the floor frames 14 and 14 described above are covered with a floor under cover 16 having a plate shape. Here, the floor under cover 16 is divided into right and left at a substantially central portion in the vehicle width direction, and the lower portion of the tunnel portion 4 is thereby opened. In this embodiment, the under floor part is mainly comprised by the floor panel 3 of the compartment 2, the tunnel part 4, and the floor under cover 16 which covers the lower part of the floor panel 3. FIG.

  A reinforcement 17 is disposed between the tunnel portion 4 and the floor frame 14 at the connection portion X between the rear end portion of the dash panel 1 and the front end portion of the floor panel 3. Further, a torque box 18 is disposed at the connection portion X on the outer side in the vehicle width direction of the floor frame 14.

  In addition, a suspension cross member (hereinafter referred to as a suspension cross) 19 for connecting the left and right suspensions (not shown) for the front wheels is disposed at the front side of the vehicle V at a position corresponding to the engine room E. Yes. The suspension cross 19 has a pair of left and right vertical members 19A and 19A mainly extending in the vehicle longitudinal direction, and a horizontal member 19B extending in the vehicle width direction and connecting the vertical members 19A and 19A.

  Each of the members 19A and 19B constituting the suspension cross 19 as described above is a tubular frame in which a closed cross section 19C is formed by joining the upper and lower panels 19a and 19b like the lateral member 19B shown in FIG. It is a member.

  At a position corresponding to the connecting portion X in the vehicle front-rear direction, a tunnel under cover 20 that covers the front portion of the tunnel portion 4 from below is disposed at the rear portion of the suspension cross 19.

  4 is a cross-sectional view taken along line B-B in FIG. 3. The tunnel undercover 20 has a substantially flat plate shape as shown in FIGS. 1 to 4, and the peripheral edge thereof is fastened to various peripheral members. For example, the front end portion of the tunnel under cover 20 is fastened to the lower surface portion (lower panel 19b) of the lateral member 19B constituting the suspension cross 19 by a fastening member 30 such as a bolt or a nut. Further, at both left and right ends of the tunnel undercover 20, the front part is fastened to the lower surface part of the vertical member 19A constituting the suspension cross 19 by the fastening member 31, while the rear part is fastened to the floor undercover by the fastening member 32. 16 is fastened inside the front end. Further, the rear end portion of the tunnel under cover 20 is fastened to the lower surface of the front end portion of the plate member 40 described later by a fastening member 33.

  Further, a plurality of slits 21, 21,... For communicating between the engine room E and the vehicle body lower side are formed on the surface of the tunnel undercover 20 so as to extend in the vehicle width direction. The plurality of slits 21 are arranged so as to be aligned in the vehicle front-rear direction, and are arranged at positions corresponding to the rear part of the engine room E in the tunnel under cover 20 that covers the front part of the tunnel part 4.

  And each slit 21 has the extension part 21a extended toward upper direction in the front edge part, as shown to FIG. 3, FIG.

  In addition, as shown in FIGS. 1 and 3, the tunnel under cover 20 is formed with a notch 22 corresponding to the position of the hanger rubber 11 and partially cut away so as to avoid interference with the hanger rubber 11. Yes. In the tunnel undercover 20, the plurality of slits 21, 21,... And the notch 22 form an opening that communicates the engine room E with the lower part of the vehicle body. In this embodiment, the opening area of the opening in the tunnel under cover 20, that is, the area occupied by each slit 21 and the notch 22 in the tunnel under cover 20 is set to about 30% of the entire tunnel under cover 20. Has been.

  On the surface of the tunnel under cover 20, a plurality of beads 23, 23,... Projecting upward are formed as shown in FIGS. These beads 23, 23,... Extend in the vehicle front-rear direction on the surface of the tunnel undercover 20.

  Further, in this embodiment, a flat plate member 40 is disposed at the rear portion of the tunnel under cover 20 so as to close the front portion of the tunnel portion 4, and the tunnel under cover 20 and the plate member 40 are fastened together. Both form a substantially continuous plane as shown in FIG.

  Furthermore, the plate member 40 has both ends in the vehicle width direction joined to the left and right lower surface portions of the tunnel portion 4, thereby connecting the lower portions of the front portion of the tunnel portion 4 in a substantially straight line.

  Further, the plate member 40 is formed with holes 41, 42, and 42 on both the left and right sides of the substantially central portion and the rear portion, and the weight of the parts is reduced by the holes 41, 42, and 42. Among these, when looking at the hole portions 42 and 42 in particular, the hole portions 42 and 42 are formed corresponding to the positions of the hanger rubbers 13 and 13, whereby the hanger rubbers 13 and 13 and the plate member are formed. Interference with 40 is avoided.

  The plate member 40 is formed with beads 43, 44, 45 protruding upward, and the rigidity of the plate member 40 is ensured by the beads 43 to 45. Of these, the beads 43, 43,... Extend obliquely so as to intersect at the hole 41, while the beads 44, 45 extend in the vehicle width direction at the vehicle front of the hole 42 and at the rear end of the plate member 40. ing.

  By the way, when the vehicle V travels, the traveling wind flows substantially straight from the front of the vehicle toward the rear under the floor under cover 16 and the tunnel under cover 20. At this time, particularly under the tunnel portion 4, the traveling wind flowing from below the suspension cross 19 is moved rearward below the vehicle body as indicated by the solid line arrow α in FIG. It flows almost straight toward you.

  On the other hand, the air heated by the engine flows into the tunnel portion 4 from the engine room E as shown by a broken line arrow β in FIG. 2, and further from the rear portion of the suspension cross 19 to the front portion of the tunnel portion 4. , Trying to flow to the outside below. However, in the present embodiment, the air is guided by the tunnel under cover 20 and the plate member 40, so that downward movement is prevented.

  In particular, in the slit 21 of the tunnel undercover 20, although the engine room E communicates with the lower part of the vehicle body, the extension part 21a extends upward at the front edge part thereof. The air is prevented from moving downward as indicated by a two-dot chain line arrow β ′ in FIG.

  As a result, the traveling wind flowing under the floor under cover 16, the tunnel under cover 20, and the plate member 40 and the air flowing into the tunnel portion 4 from the engine room E collide with each other in the vertical direction as shown in FIG. There is no flow in the rear in a substantially parallel manner.

  As described above, in the present embodiment, the tunnel under cover 20 that covers the front portion of the tunnel portion 4 is provided at the rear portion of the suspension cross 19, so that the air in the engine room E is transferred to the rear portion of the suspension cross 19 and the front portion of the tunnel portion 4. It is possible to prevent the air from flowing to the outside below and to interfere with the air and the traveling wind from the front of the vehicle. As a result, the vortex as shown by the two-dot chain line arrow γ in FIG. It can be prevented from occurring. Accordingly, air turbulence below the under floor portion of the vehicle V can be suppressed, and the aerodynamic performance of the vehicle V can be improved.

  In particular, the tunnel under cover 20 is provided at the front part of the tunnel part 4 where the vortex is likely to be generated, so that the lower part of the tunnel V is not covered all over the lower part of the under floor part of the vehicle V. The air turbulence can be effectively suppressed.

  Here, by disposing the tunnel under cover 20 only in the front part of the tunnel part 4, the rear part of the tunnel part 4 can be always opened. Thereby, the cooling performance in the tunnel part 4 can be improved, covering the front part of the tunnel part 4 efficiently.

  Therefore, in this embodiment, the tunnel undercover 20 can achieve both aerodynamic performance improvement and cooling performance improvement in the tunnel portion 4. Furthermore, since it is not necessary to open and close the lower part of the tunnel part 4, the aerodynamic performance and the cooling performance in the tunnel part 4 can be improved efficiently.

  Further, in this embodiment, the engine room E communicates with the lower part of the vehicle body by the opening including the slit 21 and the notch 22 of the tunnel undercover 20 and the holes 41 and 42 of the plate member 40. The air can be moved between the two. For this reason, when the vehicle V stops, air outside the vehicle can be introduced into the engine room E and the tunnel portion 4 via the slit 21, the notch 22, and the holes 41 and 42 described above. The cooling performance of the engine room E and the tunnel part 4 at the time of a stop of V can be improved.

  For example, in the slit 21 of the tunnel under cover 20, when the vehicle V is stopped, the air outside the vehicle is guided in the engine room E and the tunnel part 4 by the guide of the extension part 21a as indicated by the solid line arrow δ in FIG. Can be introduced.

  Here, regarding the slit 21 of the tunnel undercover 20, it is conceivable to form it so as to extend in the vehicle front-rear direction. However, since the traveling wind generally flows in the longitudinal direction of the vehicle, as described above, when the slit is formed to extend in the longitudinal direction of the vehicle along the traveling wind, the traveling wind is generated in the engine room E or This may easily flow into the tunnel portion 4 and may adversely affect aerodynamic performance. In the present embodiment, the slit 21 is formed so as to extend in the vehicle width direction, thereby suppressing the traveling wind from flowing into the engine room E or the tunnel portion 4, thereby ensuring aerodynamic performance. Is possible.

  Moreover, in this embodiment, the slit 21 has the extension part 21a in the front edge part, Therefore The air which is going to flow into the tunnel part 4 from the engine room E extends upwards. The extended portion 21 a is prevented from flowing into the tunnel portion 4.

  Further, by arranging the slit 21 at a position corresponding to the rear portion of the engine room E in the tunnel under cover 20, when the vehicle V stops, the air outside the vehicle can be easily put into the engine room E as shown in FIG. Can be introduced.

  Further, as a result of earnest research, the inventor has developed an aerodynamic performance when the opening area of the opening in the tunnel undercover 20 is set to about 30% of the entire tunnel undercover 20. It was found that both cooling performance and cooling performance can be demonstrated. Therefore, as in this embodiment, the aerodynamic performance and the cooling performance can be more reliably achieved by setting the opening area of the opening in the tunnel under cover 20 to about 30% of the entire tunnel under cover 20. Can do.

  Further, by fastening the plate member 40 to the rear portion of the tunnel under cover 20, the aerodynamic performance can be further improved by the cooperation of the tunnel under cover 20 and the plate member 40. And the deformation | transformation of the tunnel part 4 accompanying the vibration of a floor panel 3, a vehicle collision, etc. at the time of vehicle travel can also be suppressed with the plate member 40. FIG.

  The tunnel under cover 20 described above mainly plays a role of guiding the traveling wind below the vehicle V, while the plate member 40 plays a role of suppressing the vibration of the floor panel 3 in addition to the role of guiding the traveling wind. It also plays a role of suppressing deformation of the tunnel portion 4 and improving vehicle body rigidity against torsion of the vehicle body. Therefore, as shown in FIGS. 2, 5, and 6, the rigidity (plate thickness) of the plate member 40 itself is set larger (thicker) than the rigidity (plate thickness) of the tunnel undercover 20.

  In the above-described embodiment, the tunnel under cover 20 is only formed with an opening including the slit 21 and the notch 22, but, for example, a louver member that opens and closes the opening may be provided. In this case, the louver member may be operated according to the traveling state or the stopped state of the vehicle V. For example, the louver member may be used for detection results of various sensors that detect the operating state of the engine, the state of the ignition switch, or the like. It may be electrically controlled based on this.

  Further, the change lever and the louver member may be connected by a cable or the like, and the louver member may be operated in conjunction with a shift operation of the change lever. In this case, the louver member may be opened when the occupant shifts the change lever to the parking range position.

  Further, the parking brake and the louver member may be connected by a cable or the like, and the louver member may be operated in conjunction with the operation of the parking brake. In this case, the louver member may be opened when the occupant raises the parking brake.

  In the embodiment described above, the notch 22 is formed in the tunnel under cover 20 in order to avoid interference with the hanger rubber 11, but the present invention is not limited to this, and a hole similar to the slit 21 may be formed. Good.

In correspondence between the configuration of the present invention and the above-described embodiment,
The under cover of the present invention corresponds to the tunnel under cover 20,
Similarly,
The opening corresponds to the slit 21 and the notch 22,
The tunnel reinforcing member corresponds to the plate member 40,
The present invention is not limited only to the configuration of the above-described embodiment, and many embodiments can be obtained.

4 ... Tunnel part 5 ... Exhaust system 19 ... Suspension cross member 20 ... Tunnel under cover 21 ... Slit 22 ... Notch part 40 ... Plate member E ... Engine room

Claims (7)

A tunnel portion extending in the vehicle front-rear direction along the exhaust system extending in the vehicle front-rear direction in the vehicle width direction at the rear of the engine room;
An under floor structure of a vehicle having a suspension cross member connecting left and right suspensions,
An under floor structure for a vehicle, in which an under cover for covering a front portion of the tunnel portion is provided at a rear portion of the suspension cross member. 2. The underfloor structure for a vehicle according to claim 1, wherein the under cover is provided with an opening that allows air to move between a lower portion of a vehicle body and the engine room. The under floor structure for a vehicle according to claim 2, wherein the opening is a slit formed to extend in the vehicle width direction. The under floor structure for a vehicle according to claim 2 or 3, wherein the opening portion has a shape in which a front edge portion extends upward. The under floor structure for a vehicle according to any one of claims 2 to 4, wherein the opening is provided at a position corresponding to a rear portion of the engine room in the under cover. The underfloor structure for a vehicle according to any one of claims 2 to 5, wherein an opening area of the opening is set to about 30% of an entire area of the undercover. The underfloor structure for a vehicle according to any one of claims 1 to 6, wherein a substantially flat tunnel reinforcing member is connected to a rear portion of the undercover.

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