JP5733128B2 - Vehicle lower structure - Google Patents

Description

  The present invention relates to a vehicle lower structure having a subframe.

  A technique for cooling a cab-over type engine is known by causing running air flowing from an inlet formed at the front end of the suspension frame to flow out from an outlet formed at the rear end of the suspension frame (see, for example, Patent Document 1). .

JP 2002-25983 A

  By the way, in the vehicle, there is room for improvement in terms of improving aerodynamic performance.

  An object of the present invention is to obtain a vehicle lower structure that contributes to an improvement in the aerodynamic performance of a vehicle.

The vehicle lower structure according to the first aspect of the present invention is elongated in the vehicle longitudinal direction and has a closed cross-sectional structure, and includes a side rail that constitutes a subframe, and an opening on the vehicle front side that is formed in the side rail. The traveling wind that flows in and flows backward in the closed cross section of the side rail is guided by the guide portion toward the vehicle rear side opening formed on the side rail in the vehicle width direction outward , And an air guide structure that allows the vehicle to flow out from the opening on the vehicle rear side only toward the vehicle rear side of the wheel in the wheel house.
According to a second aspect of the present invention, the vehicle lower structure is elongated in the vehicle front-rear direction and has a closed cross-sectional structure, and forms a side rail and a wheel house that form a subframe, and the wheel in the wheel house is formed. A fender apron having a window portion facing the rear space, and a guide wind that flows from the opening on the front side of the vehicle formed in the side rail and flows in the closed cross section of the side rail toward the rear of the vehicle. To guide the vehicle toward an opening on the vehicle rear side formed on the laterally outward side wall of the side rail, and to guide the air out of the vehicle rear side opening into the wheel house only through the window. And a structure.

In the vehicle lower structure according to claim 1 , the traveling wind that has flowed into the side rail from the opening on the front side of the side rail that constitutes the subframe flows as a duct in the side rail of the closed cross-section structure, and Out of the side opening. Since this traveling wind flows out to the rear side of the vehicle with respect to the wheels in the wheel house, for example, turbulent flow (drag flow) caused by rotation of the wheels is suppressed.

Thus, the vehicle lower structure according to claims 1 and 2 contributes to the improvement of the aerodynamic performance of the vehicle.

Further, in the vehicle lower structure according to claims 1 and 2, the traveling direction of the traveling wind flowing toward the rear of the vehicle using the side rail as a duct is converted outward in the vehicle width direction by the guide portion. That is, the traveling wind is guided in the outflow direction from the rear opening, and efficiently flows out behind the wheels in the wheel house.

According to a third aspect of the present invention, in the lower vehicle structure according to the first or second aspect, the guide portion is formed integrally with the side rail.

  In the vehicle lower structure according to the third aspect, the guide portion is formed by projecting a part of the wall portion of the side rail into the closed cross section. For this reason, at the time of a frontal collision of the vehicle, the formation part of the guide part at the rear part of the side rail tends to be a deformation starting point of the subframe, and an effect of absorbing collision energy is obtained.

  The vehicle lower structure according to a fourth aspect of the invention is the vehicle lower structure according to any one of the first to third aspects, wherein the side rail has a vehicle front end side on the vehicle upper side than an intermediate portion in the vehicle longitudinal direction. The vehicle has a slope formed between the vehicle front end side and the intermediate portion, and the front opening is formed in the bottom wall of the slope of the side rail.

  In the vehicle lower structure according to the fourth aspect, since the opening on the front side is formed in the bottom wall of the side rail facing the front and the lower side of the vehicle, the traveling wind efficiently flows into the side rail.

  As described above, the vehicle lower structure according to the present invention has an excellent effect of contributing to the improvement of the aerodynamic performance of the vehicle.

(A) is a side view showing an automobile to which a vehicle lower part structure according to an embodiment of the present invention is applied, and (B) is a vehicle lower part according to an embodiment of the present invention along 1B-1B in FIG. 1 (A). It is a plane sectional view showing the important section of a structure. It is the perspective view looked up from the lower part which shows the sub-frame which comprises the vehicle lower part structure which concerns on embodiment of this invention. It is the perspective view which looked up from the lower part which shows the guide member which comprises the vehicle lower part structure which concerns on embodiment of this invention. It is the perspective view looked up from the downward direction which shows the modification of the guide member which comprises the vehicle lower part structure which concerns on embodiment of this invention.

  A vehicle lower structure 10 according to an embodiment of the present invention will be described with reference to FIGS. The arrow FR, arrow UP, and arrow OUT that are appropriately described in each figure indicate the front direction, the upward direction, and the outside in the vehicle width (left and right) direction of the vehicle V to which the vehicle lower structure 10 is applied, respectively. In the following description, when only the vertical direction and the vehicle width direction are shown, they correspond to the directions of the arrows.

  FIG. 1A shows a side view of an automobile V to which the vehicle lower structure 10 is applied, and FIG. 1B shows a cross section taken along line 1B-1B in FIG. The figure is shown schematically. As shown in these drawings, the vehicle lower structure 10 is applied to the front lower portion of the automobile V. The vehicle lower structure 10 is basically symmetrical with respect to the front-rear direction center line passing through the center in the vehicle width direction. Therefore, in the following description, the structure on one side mainly in the vehicle width direction will be described. To do.

(overall structure)
As shown in FIG. 1B, the vehicle lower structure 10 includes a subframe (also referred to as a suspension member) 12. As shown in FIG. 2, the subframe 12 includes a pair of left and right side rails 14 that are elongated in the longitudinal direction of the vehicle, and a front cross 16 and a rear cross 18 that bridge between the front and rear ends of the left and right side rails 14. It is configured as the main part. Thereby, the sub-frame 12 is a so-called well-shaped frame having a substantially rectangular frame shape in plan view.

  At the rear end of the side rail 14, a coupling portion 14J that is rigidly or elastically coupled to a kick portion (not shown) of a front side member that is a vehicle body skeleton is provided near the lower end of the dash panel. . Further, the front end portion 14F of the side rail 14 or the center portion 14C in the front-rear direction is rigidly or elastically coupled to a front side member front portion positioned above the front rail member via a bracket (not shown). ing.

  Although not shown in the drawings, the subframe 12 coupled to the vehicle body skeleton as described above supports a power unit including at least one of an engine and an electric motor, for example. Further, the sub-frame 12 supports the lower arm constituting the front suspension for suspending the front wheel 20 with respect to the vehicle body so that the left and right side rails 14 can swing up and down.

  The side rail 14 constituting the subframe 12 has a front end portion 14F positioned above the central portion 14C, and an inclined portion 14K is formed between the front end portion 14F and the central portion 14C. That is, the side rail 14 is configured such that the rear end of the front end portion 14F and the front end of the central portion 14C are continuous via the inclined portion 14K.

  The side rail 14 has a hollow closed cross-sectional structure. More specifically, as shown in FIG. 2, the side rail 14 includes an upper panel 22 having a substantially “U” -shaped cross section that opens downward, and a lower panel 24 having a substantially “U” -shaped cross section that opens upward. Have. The upper panel 22 and the lower panel 24 are joined by overlapping the opening end sides of the side walls 22S and 24S in the vehicle width direction, thereby forming the side rail 14 having a substantially rectangular closed sectional structure (middle structure). Yes. In this state, the left and right side walls 22S, 24S face each other in the vehicle width direction, and the top wall 22T and the bottom wall 24B face each other vertically.

  Further, as shown in FIG. 1B, the front wheel 20 as a wheel can be steered in a wheel house 26 formed in a substantially “U” shape that opens outward in the vehicle width direction in a plan view. Has been placed. The wheel house 26 is formed on a fender apron 25 that is a vehicle body panel, and is protected against stepping stones and the like by a fender liner 28 that is a resin part provided on the inner periphery thereof. The fender liner 28 can also be regarded as a member that covers the front wheel 20 from above (and front and rear). In FIG. 1B, the member disposed in front of the front cross 16 of the sub-frame 12 is a bumper cover 29 constituting a front bumper.

(Wind guide structure)
As shown in FIG. 1B, in the vehicle lower structure 10, the side rail 14 of the subframe 12 is used as a duct to guide the traveling wind to the space 26R behind the front wheels 20 in the wheel house 26. A wind structure 30 is provided. This will be specifically described below.

  As shown in FIG. 2, the air guide structure 30 has an inlet 32 as an opening on the front side that guides traveling air into the side rail 14. The inflow port 32 is formed in a portion of the bottom wall 24 </ b> B of the lower panel 24 that constitutes the inclined portion 14 </ b> K of the side rail 14. That is, the inflow port 32 is opened in the inclined surface which faces both the front and the bottom in the bottom wall 24B of the lower panel 24.

  Further, the air guide structure 30 has an outlet 34 as an opening on the rear side through which the traveling wind flows out from the side rail 14. The outflow port 34 is formed behind the inflow port 32 and facing outward in the vehicle width direction. More specifically, the outlet 34 is formed across the side walls 22S, 24S of the side rail 14 on the outer side in the vehicle width direction of the upper panel 22 and the lower panel 24. That is, the outflow port 34 includes a notch on the side wall 22S having a substantially “U” -shaped edge that opens downward, and a notch on the side wall 24S having an approximately “U” -shaped edge that opens upward. Are formed in combination. Note that the upper and lower cutouts constituting the inflow port 32 and the outflow port 34 are formed in a process of forming the upper panel 22 and the lower panel 24 by press working, respectively.

  Further, the air guide structure 30 includes a guide member 36 that guides the traveling wind that flows in from the inlet 32 and flows mainly backward in the side rails 14 to the outlet 34 side. As shown in FIG. 1 (B), the guide member 36 has a guide portion 36G that is curved so that the inner end in the vehicle width direction is located on the front side of the outer end and is concave forward and outward in plan view. And a flange portion 36F fixed to the side rail 14. As shown in FIG. 3, the guide member 36 in this embodiment is fixed to the top wall 22T at the flange portion 36F. In this state, the lower end of the guide portion 36G reaches the bottom wall 24B (illustrated). (Omitted).

  Furthermore, the rear end position of the guide portion 36G is substantially coincident with the position of the rear edge of the outflow port 34. The guide portion 36G of the guide member 36 described above converts the flow direction of the traveling wind that has flown rearward in the side rail 14 into a flow direction outward (inclusive of components) in the vehicle width direction. Yes.

  The outlet 34 communicates with a space 26 </ b> R behind the front wheel 20 in the wheel house 26 through a window portion 25 </ b> W formed in the fender apron 25. More specifically, the window portion 25W is formed to face a space 26R between the front wheel 20 and a rear portion 28R that covers the front wheel 20 of the fender liner 28 from the rear.

  As described above, the air guide structure 30 causes the traveling wind flowing into the side rail 14 from the inlet 32 to pass between the front wheel 20 and the rear portion 28R of the fender liner 28 in the wheel house 26 through the outlet 34 and the window 25W. It is configured to flow out (blow out) into the space 26R.

  Next, the operation of the embodiment will be described.

  When the vehicle V to which the vehicle lower structure 10 having the above configuration is applied travels, the traveling wind F flows into the side rail 14 from the inlet 32 of the side rail 14 constituting the subframe 12. The traveling wind F flows rearward as a duct in the side rail 14, and flows out from the outlet 34 outward in the vehicle width direction while being guided by the guide portion 36G. The traveling wind F that has flowed outward in the vehicle width direction from the outlet 34 flows out into the space 26R between the front wheel 20 and the rear portion 28R of the fender liner 28 in the wheel house 26 through the window portion 25W.

  In the wheel house 26, a turbulent flow is likely to occur due to an air flow that flows into the wheel house 26 from below at the rear of the front wheel 20 so as to be dragged by the front wheel 20 that rotates as the automobile V travels.

  Here, in the vehicle lower structure 10, the traveling wind F flows out behind the front wheel 20 in the wheel house 26, so that a drag flow accompanying the rotation of the front wheel 20 that causes turbulent flow in the wheel house 26 is generated. Is suppressed. In other words, the drag flow accompanying the rotation of the front wheel 20 is prevented from flowing into the wheel house 26 from below by the traveling wind F flowing into the wheel house 26 from the inner side in the vehicle width direction.

  Thereby, since the generation | occurrence | production of the turbulent flow in the wheel house 26 is suppressed, compared with the comparative example which is not provided with the vehicle lower structure 10, the aerodynamic performance of the motor vehicle V to which the vehicle lower structure 10 is applied is improved.

  In particular, since the vehicle lower structure 10 includes the guide member 36 that guides the traveling wind F toward the outlet 34, the traveling wind F that has flowed into the side rail 14 can be efficiently discharged toward the wheel house 26. Can do. That is, the traveling wind F can be stably discharged toward the wheel house 26 while suppressing the generation of vortices.

  Moreover, since the inflow port 32 is disposed at a portion of the bottom wall 24B constituting the inclined portion 14K, in other words, since the inflow port 32 is opened forward, the traveling wind F can be efficiently transmitted to the side rail 14. Introduced in. In particular, since the inflow port 32 is disposed in the inclined portion 14K that is located away from the bumper cover 29 in the front-rear direction, the traveling wind flows to the bumper cover 29 as compared with the configuration in which the inflow port is provided in the front end portion 14F. Easy to flow smoothly without being blocked. In addition, since the high-level difference in the vertical direction of the flow path of the traveling wind is small as compared with the configuration in which the inflow port is provided in the front end portion 14F, the traveling wind flowing into the side rail 14 flows smoothly. Accordingly, in the vehicle lower structure 10, the traveling wind F can be efficiently discharged into the wheel house 26 while using the side rails 14 of the subframe 12 as ducts.

  Further, in the case of a frontal collision of the automobile V, a collision load is applied to the subframe 12 backward via a vehicle body skeleton such as a front side member. Here, the sub-frame 12 in which the outflow port 34 is formed is deformed starting from the outflow port 34 due to the above-described collision load. That is, the outflow port 34 functions as a weakened portion or a deformation promoting portion in the subframe 12 and contributes to acceleration of absorption of impact energy. By absorbing the collision energy due to the deformation of the subframe 12, the acceleration (load) acting on the protected portion (vehicle compartment or the like) of the automobile V is reduced as compared with the comparative example in which the outlet 34 is not formed. . That is, the vehicle lower structure 10 also contributes to occupant protection during a frontal collision.

  Next, a modified example of the guide portion that guides the traveling wind F that flows rearward in the side rail 14 toward the outlet 34 will be described.

  FIG. 4 shows an upper portion 40U of a guide portion 40 according to a modification provided in place of the guide member 36. As shown in this figure, the upper portion 40U of the guide portion 40 is integrated with the upper panel 22 by denting the top wall 22T and the left and right side walls 22S of the upper panel 22 inwardly (inside the closed cross section of the side rail 14). Is formed. Although not shown, the lower portion of the guide portion 40 is integrally formed with the lower panel 24 so as to be vertically symmetrical with the upper portion 40U. And by joining the upper panel 22 and the lower panel 24, the upper part and the lower part are faced up and down, and the guide part 40 is formed.

  In the configuration including the guide portion 40, both the outlet 34 and the guide portion 40 function as a weakening portion or a deformation promoting portion of the subframe 12. For this reason, it is easy to set a load that causes the subframe 12 to be deformed by a frontal collision. For example, as compared with the configuration including the guide member 36, the subframe 12 can be deformed with a lower load. Further, for example, as compared with the configuration provided with the guide member 36, the dimensional shape of the outlet 34 is made to be suitable for the outflow of the traveling wind F to the wheel house 26 while maintaining the load for deforming the subframe 12. Can be.

  In the above-described embodiment, an example in which the vehicle lower structure 10 includes the guide member 36 or the guide portion 40 has been described, but the present invention is not limited to this. Also in this configuration, since the rear portion of the side rail 14 is closed, at least a part of the air flow flowing out from the outflow port 34 flows outward in the vehicle width direction.

  In the above-described embodiment, the outlet 34 and the window 25W may be connected by a duct member or the like.

  Further, in the above-described embodiment, the example in which the inflow port 32 faces the front side by being arranged in the inclined portion 14K of the side rail 14 is shown, but the present invention is not limited to this. For example, the inflow port 32 may be formed at the front end of the side rail 14, or an aerodynamic member that introduces the traveling wind F to the inflow port 32 that opens downward may be used.

  Furthermore, in the above-described embodiment, an example in which the vehicle lower structure 10 is applied to the front portion of the automobile V has been described. However, the present invention is not limited thereto, and includes, for example, a rear-side subframe and a rear wheel. And may be applied to the rear portion of the automobile V.

  Thus, the present invention can be implemented with various modifications without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Vehicle lower structure 12 Sub frame 14 Side rail 14K Inclined part 14F Front end part (front end side)
14C Central part 20 Front wheel (wheel)
22S side wall 24S side wall 24B bottom wall 26 wheel house 30 air guide structure 32 inflow port (opening on the vehicle front side)
34 Outlet (Vehicle rear opening)
36G guide part 40 guide part

Claims (4)

A side rail that is elongated in the vehicle longitudinal direction and has a closed cross-sectional structure, constituting a subframe;
Running wind that flows in from the opening on the front side of the vehicle formed in the side rail and flows backward in the closed cross section of the side rail is formed on the side rail of the side rail outward in the vehicle width direction by the guide portion. A wind guide structure that guides toward an opening on the rear side of the vehicle , and flows out from the opening on the rear side of the vehicle toward only the vehicle rear side of the wheel in the wheel house,
Vehicle lower structure equipped with. A side rail that is elongated in the vehicle longitudinal direction and has a closed cross-sectional structure, constituting a subframe;
A fender apron that forms a wheel house and has a window portion facing the space behind the wheel in the wheel house;
Running wind that flows in from the opening on the front side of the vehicle formed in the side rail and flows backward in the closed cross section of the side rail is formed on the side rail of the side rail outward in the vehicle width direction by the guide portion. A wind guide structure that guides toward the opening on the rear side of the vehicle , and flows into the wheel house only through the window portion from the opening on the rear side of the vehicle;
Vehicle lower structure equipped with . The vehicle lower structure according to claim 1 , wherein the guide portion is formed integrally with the side rail. The side rail has an inclined portion formed between the vehicle front end side and the intermediate portion so that the vehicle front end side is located on the vehicle upper side than the intermediate portion in the vehicle front-rear direction.
The vehicle lower structure according to any one of claims 1 to 3, wherein the opening on the front side is formed in a bottom wall of an inclined portion of the side rail.

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