WO2019176789A1

WO2019176789A1 - Floor structure

Info

Publication number: WO2019176789A1
Application number: PCT/JP2019/009411
Authority: WO
Inventors: 豊三日月; 中田　匡浩; 栄志磯貝
Original assignee: 日本製鉄株式会社
Priority date: 2018-03-13
Filing date: 2019-03-08
Publication date: 2019-09-19
Also published as: JP7006771B2; CN111819129A; JPWO2019176789A1

Abstract

The present invention provides a floor structure that is provided with: a floor panel that includes a wave-shaped part having ridge line sections parallel to a vehicle width direction or a vehicle length direction; and a side sill that is joined to an end section of the floor panel in the vehicle width direction W. The value of C/√h, where C is the cycle of protruding sections in the floor panel, and h is the height thereof, is less than 60.

Description

Floor structure

The present invention relates to an automobile floor structure.

The floor structure of an automobile includes, for example, a floor panel, a side sill, a floor cross member, and other reinforcing members. In such a floor structure, for example, at the time of a side collision of an automobile, in particular, at the time of a pole side collision, a shock is absorbed mainly by bending deformation of the side sill and crushing deformation of the floor cross member, thereby securing a living space for the occupant. Yes. At this time, the floor panel is required not to be greatly deformed in order to secure the occupant's living space and to support the load from the side sill.

In recent years, a vehicle body layout in which a large-capacity battery is mounted under the floor panel has been adopted for the purpose of increasing the cruising range of an electric vehicle. In the vehicle body having such a layout, it is desired that the impact is surely absorbed by the deformation of the side sill so as not to damage the battery from the viewpoint of electrical safety at the time of a pole side collision. Therefore, it is necessary to enhance the load bearing performance when the side sill is deformed, and the floor panel is required to withstand the high load transmitted from the side sill so that the floor panel does not deform greatly. Note that a member such as a floor panel is greatly deformed so that a load input to the member is smaller than that before the large deformation. However, in this specification, the maximum input load before the member is largely deformed is referred to as “proof strength”.

On the other hand, in an electric vehicle, a driving component called a propeller shaft and an exhaust pipe are not required compared to a conventional vehicle. Therefore, a step shape called a tunnel provided at the center of the floor panel in the vehicle width direction is not required, and the floor panel can be formed into a substantially flat shape. From the viewpoint of processing such as press molding, a substantially flat floor panel can be easily provided with a shape such as emboss as compared with a conventional floor panel.

Conventional floor structures are described in Patent Documents 1 to 3. Patent Document 1 discloses a structure in which a reinforcing member is joined to the lower surface of the center portion in the vehicle width direction of the front portion of the cab floor as a cab over type cab floor reinforcing structure. In the floor structure of Patent Document 1, the reinforcement member is formed with a plurality of bead portions extending in the vehicle length direction, thereby suppressing deformation against external force in the vehicle length direction.

In Patent Document 2, as a vehicle floor structure, a corrugated plate having a ridge line extending in the vehicle length direction is joined to the lower side (vehicle outer side) of the floor panel, and a vehicle plate is connected to the end of the corrugated plate in the vehicle length direction. A structure in which cross members extending in the width direction are joined is disclosed. In the floor structure of Patent Document 2, the upper edge portion of the corrugated plate is joined to the floor panel, the end portion in the vehicle width direction of the corrugated plate is joined to the floor frame, and the end portion in the vehicle length direction of the corrugated plate is on the bottom surface of the cross member. The structure is abutted or joined. By adopting such a floor structure, for example, an input load at the time of an offset frontal collision is distributed to the left and right floor frames.

In Patent Document 3, as a vehicle floor structure, there is a structure having a floor panel, side sills joined to both sides of the floor panel, and cross members arranged between the side sills so as to be orthogonal to the side sills. It is disclosed. In the floor structure of Patent Document 3, concentric arc-shaped beads are formed on the floor panel centering on a portion where the cross member and the side sill intersect, thereby dispersing the input load at the time of a side collision.

JP 2000-135990 A JP 2004-168252 A JP 2006-297966 A

The floor structure is required to have improved proof stress, while light weight is also required to improve fuel efficiency. Therefore, it is required for the floor structure of an automobile to satisfy both of securing of proof stress and weight reduction. For this purpose, it is required to improve the yield strength per unit mass (proof strength / mass), that is, the mass efficiency related to the yield strength. If the mass efficiency can be improved, it is possible to ensure sufficient yield strength even if the plate thickness of the member is reduced to reduce the weight. Further, the floor structure is desired to be a simple structure in order to expand the indoor space or the battery mounting space.

The floor structure of Patent Document 1 is a structure in which a closed section is formed by a floor tunnel and a reinforcing member, and an increase in the number of parts and an increase in mass are caused by combining large-sized members for forming the closed section. Moreover, the floor structure of patent document 1 is a structure which suppresses a deformation | transformation by improving what is called energy absorption performance which transmits a high load, deform | transforming the front center of a cab floor and a reinforcement member in the case of a frontal collision. Therefore, when focusing on the proof stress, the floor structure of Patent Document 1 does not always provide sufficient proof strength.

The floor structure of Patent Document 2 is a structure in which a closed section is formed by a floor panel and a corrugated plate, and an increase in the number of parts and an increase in mass are caused by combining large-sized members for forming the closed section. Further, the floor structure of Patent Document 2 is a structure in which the upper ridge portion of the corrugated plate is joined to the floor panel, and the end portion in the vehicle length direction of the corrugated plate contacts the bottom surface of the cross member. Limited by the height of the cross member. Due to such restrictions, the floor structure of Patent Document 2 has a limit in improving the mass efficiency of yield strength. Furthermore, since the floor structure of Patent Document 2 is a floor structure on the premise that a cross member is provided, it is disadvantageous in terms of expansion of indoor space or battery mounting space.

The floor structure of Patent Document 3 is a structure in which a closed section is formed by a floor panel and a cross member, and as a result of combining large-size members for forming the closed section, an increase in the number of parts and an increase in mass are caused. Further, the bead shape formed on the floor panel functions effectively when it has a cross member, and the mass efficiency of yield strength is greatly reduced in a floor structure in which no cross member is arranged. Moreover, since the floor structure of patent document 3 is a floor structure on the assumption that a cross member is provided, it is disadvantageous from the viewpoint of expansion of an indoor space or a battery mounting space.

The present invention has been made in view of such problems of the prior art, and is (a) a simple structure that does not have a closed cross section formed by a cross member for collision, and (b) relates to strength. An object of the present invention is to provide a floor structure with improved mass efficiency.

In order to solve the above problems, the present inventor conducted a collision simulation simulating a substantially flat floor panel and a side sill, and as a result of earnestly examining the relationship between the behavior of the out-of-plane deformation of the floor panel and the maximum input load, With this knowledge, the present invention was completed. That is, the present inventor gives a corrugated shape having a ridge line portion parallel to the vehicle width direction or the vehicle length direction to the floor panel, and uses the period C and the height h of the convex portion of the floor panel. It has been found that the above problem can be solved when the value of h is less than 60.

Therefore, one aspect of the present invention for solving the above problems is a floor structure, which includes a floor panel having a corrugated portion having a ridge line portion parallel to the vehicle width direction or the vehicle length direction, and the vehicle of the floor panel. A side sill joined to an end portion in the width direction, and a value of C / √h using a height C and a period C of the convex portion of the corrugated portion is less than 60. *

According to the present invention, it is possible to provide a floor structure that has a simple structure that does not have a closed cross-section formed by a cross member for collision, and has improved mass efficiency regarding yield strength.

It is a perspective view showing a schematic structure of a floor structure concerning a 1st embodiment of the present invention. It is a top view showing a schematic structure of a floor structure concerning a 1st embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 3 is a sectional view taken along line BB in FIG. FIG. 3 is a view corresponding to the BB cross-sectional view of FIG. 2 showing an example of the shape of the floor panel. It is a perspective view which shows schematic structure of the floor structure concerning 2nd Embodiment of this invention. It is a figure equivalent to the AA sectional view in Drawing 2 of the floor structure concerning a 2nd embodiment of the present invention. It is a perspective view which shows schematic structure of the floor structure concerning 3rd Embodiment of this invention. It is CC sectional drawing of FIG. It is a figure which shows the joining example of the floor panel and side sill which used the L-shaped bracket. It is sectional drawing when a bracket is seen from the vehicle inside which shows the example of a shape of an L-shaped bracket. It is a figure which shows the example when the period C is not constant. It is a figure which shows the example in case the height h is not constant. It is a figure which shows the example in case the period C and height h are not constant. It is a figure which shows the analysis model in a side collision simulation (A). It is a figure which shows the analysis model in a side collision simulation (A). It is DD sectional drawing of FIG. It is a figure which shows the analysis model in a side collision simulation (A). It is a figure which shows the relationship between the displacement of the pole in a comparative example and an Example, and the input load to a floor panel. In addition, the vertical axis | shaft of this figure is represented by the load ratio which normalized the input load in each analysis model with the maximum input load of the comparative example 1. FIG. It is a figure which shows the state of the out-of-plane deformation of the comparative example 1. It is a figure which shows the state of the out-of-plane deformation | transformation of Example 1. FIG. It is a figure which shows the relationship between the period C and the maximum input load when the height h / period C of the convex part of a floor panel is 0.067. In addition, the vertical axis | shaft of this figure is represented by the maximum load ratio which normalized the maximum input load in each analysis model with the maximum input load of the comparative example 1. FIG. It is a figure which shows the relationship between C / (root) h of the convex part of a floor panel, and the mass efficiency of yield strength in each analysis model.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<First Embodiment>
As shown in FIGS. 1 to 3, the floor structure 1 of the first embodiment includes a floor panel 2 and a side sill 3. The side sill 3 includes a side sill outer 4 and a side sill inner 5.

The side sill outer 4 is a hat-shaped member having a cross section perpendicular to the vehicle length direction L. The side sill outer 4 extends in the vehicle height direction H, and both ends of the top surface portion 4a in the vehicle height direction H extend in the vehicle width direction W. It has the vertical wall part 4b extended inside a vehicle, and the flange part 4c extended perpendicularly | vertically with respect to the said vertical wall part 4b from the front-end | tip part of the vertical wall part 4b. Similarly, the side sill inner 5 is a hat-shaped member having a cross section perpendicular to the vehicle length direction L. The top surface portion 5a extends in the vehicle height direction H, and the vehicle width direction from both ends in the vehicle height direction H of the top surface portion 5a. It has the vertical wall part 5b extended to the vehicle outer side of W, and the flange part 5c extended perpendicularly | vertically with respect to the said vertical wall part 5b from the front-end | tip part of the vertical wall part 5b. The side sill outer 4 and the side sill inner 5 are joined by, for example, spot welding of the flange portion 4c and the flange portion 5c. Note that the hat shape of the side sill outer 4 and the hat shape of the side sill inner 5 include, for example, a substantially hat shape in which the vertical wall portion is inclined with respect to the top surface portion. Further, for example, one of the side sill outer 4 and the side sill inner 5 may be a flat plate member.

As shown in FIG. 4, the floor panel 2 has a corrugated shape having a periodically formed convex portion 10, a bottom surface portion 11, and a ridge line portion 12 that is a corner portion connecting the convex portion 10 and the bottom surface portion 11. It has become. The convex part 10 of the floor panel 2 in the first embodiment includes a top surface part 10a, a side wall part 10b extending in the vehicle height direction H from both ends of the top surface part 10a, and a corner part connecting the top surface part 10a and the side wall part 10b. And a ridge line portion 10c. The ridge lines 10c and 12 are parallel to the vehicle width direction W. That is, the longitudinal direction of the convex portion 10 is parallel to the vehicle width direction W. Moreover, in the floor panel 2 of 1st Embodiment, the length of the top surface part 10a and the bottom face part 11 of the vehicle length direction L is mutually the same. Such a corrugated floor panel 2 is manufactured by imparting a shape to a flat plate by, for example, transfer by a roll or press molding.

As shown in FIG. 3, the end of the floor panel 2 in the vehicle width direction W (hereinafter, “end in the width direction”) is joined in contact with the side sill 3. More specifically, in the state in which the width direction end of the floor panel 2 is in contact with the top surface 5a of the side sill inner 5, the width direction end and the top surface 5a are joined by fillet welding, for example.

The floor structure 1 of the first embodiment is configured as described above. Here, the height from the bottom surface portion 11 of the corrugated portion of the floor panel 2 to the top surface portion 10a is defined as h, and the period of the convex portion 10 of the corrugated portion is defined as C. In the present specification, “period of the convex portion” means an interval from a boundary position between the convex portion 10 and the bottom surface portion 11 to a boundary position between the convex portion 10 adjacent to the convex portion 10 and the bottom surface portion 11. To do. In the case of the shape of the convex portion 10 of the first embodiment, the period C is the interval from the side wall portion 10 b of the first convex portion 10 to the side wall portion 10 b of the second convex portion 10 among the adjacent convex portions 10. is there. Further, as shown in FIG. 5, for example, when the side wall portion 10 b of the convex portion 10 is inclined with respect to the top surface portion 10 a, the period C is equal to the inner surface P ₁ of the side wall portion 10 b of the first convex portion 10. is the spacing from the intersection of the lower surface P ₂ of the bottom portion 11, an inner surface P ₁ of the second side wall portion 10b of the protrusion 10, until the line of intersection of the lower surface P ₂ of the bottom portion 11.

In the floor structure of the first embodiment, for example, out-of-plane deformation occurs in the top surface portion 10a and the bottom surface portion 11 of the floor panel 2 at the time of a side collision of an automobile, but as the period C becomes smaller, each top surface portion 10a and each bottom surface. The length of the portion 11 in the vehicle length direction L is shortened. As a result, the span where bending deformation can occur in each top surface portion 10a and each bottom surface portion 11 is shortened, and out-of-plane deformation is unlikely to occur. As a result, the proof stress of the floor panel 2 is improved. The period C of the convex portion 10 is preferably 15 to 200 mm. On the other hand, with respect to the height h of the convex portion 10, the higher the height h, the higher the bending rigidity against bending deformation with the vehicle length direction L as the rotation axis, so the proof stress of the floor panel 2 is easily improved. The height h of the convex portion 10 is preferably 2 to 20 mm.

When the period C is reduced and the height h is increased, the amount of material used when the floor panel 2 is manufactured increases and the mass of the floor panel 2 increases accordingly. Therefore, the balance between the cycle C and the height h is important from the viewpoint of achieving both yield strength and weight reduction. In this regard, in the floor panel 2 of the first embodiment, the corrugated portion is formed so that C / √h is less than 60. The floor panel 2 in which C / √h is less than 60 has improved proof mass efficiency relative to a floor panel having C / √h of 60 or more. That is, by replacing the conventional floor panel with the floor panel 2 as in the first embodiment, the mass efficiency of yield strength as the floor structure is also improved. In order to further enhance the effect, C / √h is preferably 55 or less, and more preferably 25 or less. In order to further enhance the effect, the floor panel is preferably a steel plate having a tensile strength of 780 MPa or more.

Further, according to the floor structure 1 as in the first embodiment, sufficient strength can be exerted without the floor panel 2 having a closed cross-sectional structure, so that the floor structure is configured without providing a reinforcing member such as a cross member. It is also possible to do. As a result, the indoor space or the battery mounting space can be expanded. However, from the viewpoint of improving the proof stress, the proof strength of the floor structure 1 can be further increased by providing a reinforcing member such as a cross member on the floor structure 1 as in the first embodiment.

Note that the lower limit of C / √h is not particularly limited. For example, the lower limit of the period C is constrained from the viewpoint of formability of the floor panel 2, or the upper limit of the height h is constrained from the viewpoint of securing indoor space or battery mounting space, and the lower limit of C / √h is appropriately determined. C / √h is preferably 3.34 or more.

Second Embodiment
As shown in FIGS. 6 and 7, in the second embodiment, the shape of the end portion in the width direction of the floor panel 2 is different from that in the first embodiment. In the floor panel 2 of the second embodiment, the end in the width direction is a flange portion 13 raised by, for example, bending. And the floor panel 2 and the side sill 3 are joined by spot welding in the state which the bottom face part 11 of the flange part 13 contact | abutted to the top | upper surface part 5a of the side sill inner 5. FIG. Thus, in the floor structure 1 of 2nd Embodiment, the width direction edge part of the floor panel 2 is the flange part 13, Therefore Spot welding can be employ | adopted for joining of the floor panel 2 and the side sill 3. FIG. . As a result, the joining operation between the floor panel 2 and the side sill 3 is facilitated, and the productivity is improved.

In addition, when performing spot welding, it is preferable that the length of the bottom face part 11 of the flange part 13 in the vehicle length direction L is 15 mm or more in order to ensure a sufficient spot hitting space. 6 and 7, the flange portion 13 of the floor panel 2 has a shape that extends upward in the vehicle height direction H, but may have a shape that extends downward.

<Third Embodiment>
As shown in FIGS. 8 and 9, the floor panel 2 of the third embodiment has the same shape as the floor panel 2 of the first embodiment, and the flange portion 13 as in the second embodiment is not formed. In the third embodiment, the end in the width direction of the floor panel 2 is in contact with the top surface portion 5 a of the side sill inner 5, and the floor panel 2 and the side sill 3 are joined via the bracket 6. The bracket 6 is a member extending in the vehicle length direction L and having a L-shaped cross section perpendicular to the vehicle length direction L. In the present specification, the two wall surface portions perpendicular to each other of the bracket 6 are referred to as “first wall surface portion 6a” and “second wall surface portion 6b”, respectively.

In the floor structure 1 of 3rd Embodiment, the bracket 6 is arrange | positioned above the floor panel 2 (vehicle inside), the 1st wall surface part 6a is joined to the top | upper surface part 10a of the floor panel 2, and the 2nd wall surface part 6b. Is joined to the top surface portion 5 a of the side sill inner 5. Although the joining method of members is not specifically limited, For example, spot welding is employ | adopted. When employing spot welding, the length of the top surface portion 10a of the floor panel 2 in the vehicle length direction L is preferably 15 mm or more in order to ensure a sufficient spot hitting space.

According to the floor structure 1 of the third embodiment, it is not necessary to form the flange portion 13 of the floor panel 2 as in the second embodiment, and the manufacturing of the floor panel 2 is facilitated. Furthermore, since spot welding can be adopted for joining the floor panel 2 and the side sill 3, the joining operation of the floor panel 2 and the side sill 3 becomes easy. Thereby, it becomes easy to make the floor structure 1, and productivity can be improved.

When using the bracket 6 of the third embodiment, the bracket 6 may be disposed between the floor panel 2 and the side sill 3 as shown in FIG. In the example shown in FIG. 10, the first wall surface portion 6 a of the bracket 6 is bonded to the lower surface of the bottom surface portion 11 of the floor panel, and the second wall surface portion 6 b is bonded to the upper surface of the top surface portion 5 a of the side sill inner 5. On the other hand, in the example shown in FIG. 10, since a load is first input from the side sill 3 to the bracket 6 in the case of a side collision, the bracket 6 is deformed before the floor panel 2. For this reason, depending on the load input state, the deformation of the floor panel 2 may be induced following the deformation of the bracket 6. Therefore, it is preferable that the bracket 6 is arranged so that the vehicle width direction end of the floor panel 2 abuts against the side sill 3 as in the floor structure 1 shown in FIGS. 8 and 9. Thereby, since a load is directly input to the floor panel 2 from the side sill 3 at the time of a side collision, the proof stress as the floor structure 1 can be improved.

Further, as shown in FIG. 11, the first wall surface portion 6 a of the bracket 6 of the third embodiment may have a corrugated portion similar to the corrugated portion of the floor panel 2. In the example shown in FIG. 11, the convex part 7 is periodically formed in the 1st wall surface part 6a of the bracket 6, and the convex part 7 of the 1st wall surface part 6a and the convex part 10 of the floor panel 2 exist. The bracket 6 and the floor panel 2 are joined so as to contact each other. If the bracket 6 having such a first wall surface portion 6a is used, the joint strength between the bracket 6 and the floor panel 2 can be increased, and the proof stress as the floor structure 1 can be improved.

In addition, in 3rd Embodiment, although the bracket 6 was provided in the upper side (vehicle inner side) of the floor panel 2, you may be provided in the lower side (vehicle outer side) of the floor panel 2. FIG. When the bracket 6 is provided on the lower side (the vehicle outer side) of the floor panel, the first wall surface portion 6 a of the bracket 6 is joined to the lower surface of the bottom surface portion 11 of the floor panel 2, and the second wall surface portion 6 b is connected to the side sill inner 5. Is joined to the top surface portion 5a. In the third embodiment, the shape of the bracket 6 is L-shaped, but other shapes may be used as long as the floor panel 2 and the side sill 3 can be joined.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

For example, the floor panel 2 may not have a wave shape over the entire region in the vehicle length direction L, and may have a wave shape only in a part of the section in the vehicle length direction L. Even in such a floor structure, if C / √h is less than 60 in the portion of the floor panel 2 to which the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. When only a part of the section in the vehicle length direction L is corrugated, the range of the corrugated portion is, for example, 200 mm or more in front of the vehicle length direction L around the collision position of the pole in the pole side collision test, and the rear It is preferable that it is 200 mm or more. In addition, by giving a waveform over the entire region in the vehicle length direction L of the floor panel 2 as in the above embodiment, high proof stress can be exhibited regardless of the load input position at the time of a side collision, and robustness can be achieved. An excellent floor structure can be obtained.

The floor panel 2 may not have a wave shape over the entire region in the vehicle width direction W, and only the end in the width direction may have a wave shape. Even in such a floor structure, if C / √h is less than 60 in the portion to which the corrugation at the end in the width direction is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. In addition, when only the width direction edge part is corrugated, the range of the corrugated part is the width of the floor panel 2 (from one side sill of the vehicle body to the other, starting from the end point in the vehicle width direction W of the floor panel 2. It is preferable that it is 1/4 or more of the length in the vehicle width direction W to the side sill.

As shown in FIG. 12, the period C of the convex part 10 of the floor panel 2 may not be constant. In this case, the “cycle C” is an average value of the cycles C of the convex portions 10. For example, when four convex portions 10 having different periods are provided as shown in FIG. 12, the period of the first convex portion 10 is “C ₁ ”, and the second is located next to the first convex portion 10. Assuming that the period of the convex part 10 is “C ₂ ” and the period of the third convex part adjacent to the second convex part 10 is “C ₃ ”, the period C in this specification is (C ₁ + C _2). + C ₃ ) / 3. Thus, even in a floor structure in which the period C is not constant, if C / √h is less than 60 in a portion to which a wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. If the period C is not constant, C / √h may not be less than 60 over the entire region in the vehicle length direction L. For example, even if the floor panel 2 has a wave shape over the entire region in the vehicle length direction L, the value of C / √h using the average period C and the height h of some sections in the vehicle length direction L If it is less than 60, the mass efficiency of yield strength is improved in the section. Therefore, if attention is paid to the section, the floor structure has a C / √h of less than 60, so it can be said that the floor structure according to the present invention.

As shown in FIG. 13, the height h of the convex portion 10 of the floor panel 2 may not be constant. In this case, the “height h” is an average value of the heights h of the convex portions 10. For example, when four convex portions 10 having different heights are provided as shown in FIG. 13, the height of the first convex portion 10 is “h ₁ ”, which is located next to the first convex portion 10. Assuming that the height of the second convex portion 10 is “h ₂ ” and the height of the third convex portion located next to the second convex portion 10 is “h ₃ ”, the height h in this specification is This is a value calculated by (h ₁ + h ₂ + h ₃ ) / 3. Even in the floor structure where the height h is not constant as described above, if C / √h is less than 60 in the portion where the wave shape is given, the mass efficiency of the proof stress is improved as described in the above embodiment. . Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. When the height h is not constant, C / √h may not be less than 60 over the entire region in the vehicle length direction L. For example, even if the floor panel 2 has a wave shape over the entire region in the vehicle length direction L, the value of C / √h using the average value of the height h and the period C of some sections in the vehicle length direction L If it is less than 60, the mass efficiency of yield strength is improved in the section. Therefore, if attention is paid to the section, the floor structure has a C / √h of less than 60, so it can be said that the floor structure according to the present invention.

Moreover, as shown in FIG. 14, the period C and height h of the convex part 10 of the floor panel 2 do not need to be constant, respectively. The “cycle C” in this case is the average value of the period C of each convex portion 10 as in FIG. 12, and the “height h” is the average of the height h of each convex portion 10 as in FIG. Value. For example, as shown in FIG. 14, when four convex portions 10 having different periods and different heights are provided, the period C is calculated by (C ₁ + C ₂ + C ₃ ) / 3, and the height h Is calculated by (h ₁ + h ₂ + h ₃ ) / 3. In this way, even in a floor structure in which the period C and the height h are not constant, if C / √h is less than 60 in the portion to which the wave shape is given, the mass of the proof stress as described in the above embodiment. Efficiency is improved. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. Note that if the period C and the height h are not constant, C / √h may not be less than 60 over the entire vehicle length direction L. For example, even if the floor panel 2 has a wave shape over the entire region in the vehicle length direction L, C that is the average period of some sections in the vehicle length direction L and h that is the average height of the sections are used. If the value of C / √h is less than 60, the mass efficiency of yield strength is improved in the section. Therefore, if attention is paid to the section, the floor structure has a C / √h of less than 60, so it can be said that the floor structure according to the present invention.

The height h of the convex portion 10 of the floor panel 2 may be different depending on the position in the vehicle width direction W. In this case, the “height h” is an average value of heights different from each other at the position in the vehicle width direction W. Even in such a floor structure, if C / √h is less than 60 in the portion where the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. In addition, when the height h of the convex portion 10 varies depending on the position in the vehicle width direction W, C / √h may not be less than 60 over the entire region in the vehicle width direction W. If √h is less than 60, the yield strength of the floor panel 2 is improved. The range in which C / √h in this case is less than 60 is the width of the floor panel 2 (the vehicle width direction W from one side sill of the vehicle body to the other side sill, starting from the end point of the floor panel 2 in the vehicle width direction W). The length is preferably ¼ or more of the length.

In the above description, the convex portion 10 of the floor panel 2 is configured by the top surface portion 10a, the side wall portion 10b, and the ridge line portion 10c. However, the shape of the convex portion 10 is not particularly limited. The cross-sectional shape perpendicular to the longitudinal direction may be circular. In this case, the “height h” is a height from the bottom surface portion 11 to the farthest position of the convex portion 10. Even in such a floor structure, if C / √h is less than 60 in the portion where the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less.

Further, in the above description, the

ridgeline portions

10c and 12 of the floor panel 2 are parallel to the vehicle width direction W and the floor structure is adapted to the side collision, but the

ridgeline portions

10c and 12 are arranged in the vehicle length direction L of the floor panel 2. It is good also as a floor structure corresponding to front collision or rear collision. Even in such a floor structure, if C / √h is less than 60 in the portion where the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less.

Even when the

ridge portions

10c and 12 are parallel to the vehicle length direction L, the floor panel 2 may not be corrugated over the entire region in the vehicle width direction W, and only a portion of the section in the vehicle width direction W is corrugated. There may be. Even in such a floor structure, if C / √h is less than 60 in the portion of the floor panel 2 to which the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. When only a part of the section in the vehicle width direction W has a wave shape, the range of the wave shape portion is, for example, 200 mm or more from the center position in the vehicle width direction W of the floor panel 2 to the right in the vehicle width direction W, And it is preferable that it is 200 mm or more to the left.

Even when the

ridge portions

10c and 12 are parallel to the vehicle length direction L, the floor panel 2 may not be wavy throughout the vehicle length direction L. The end portion of the vehicle length direction L (hereinafter referred to as “longitudinal direction”). Only the edge ") may be wavy. Even in such a floor structure, if C / √h is less than 60 in the portion to which the corrugation at the end in the longitudinal direction is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. When only the longitudinal end portion is corrugated, the range of the corrugated portion is 1 of the length from the front end to the rear end of the floor panel 2 starting from the end point of the floor panel 2 in the vehicle length direction L. / 4 or more is preferable.

Also when the

ridges

10c and 12 are parallel to the vehicle length direction L, the period C of the convex part 10 of the floor panel 2 may not be constant. In this case, the “cycle C” is an average value of the cycles C of the convex portions 10. Even in such a floor structure, if C / √h is less than 60 in the portion where the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. If the period C is not constant, C / √h may not be less than 60 over the entire region in the vehicle width direction W. For example, even if the floor panel 2 has a wave shape over the entire region in the vehicle width direction W, the value of C / √h using the average period C and the height h of some sections in the vehicle width direction W If it is less than 60, the mass efficiency of yield strength is improved in the section. Therefore, if attention is paid to the section, the floor structure has a C / √h of less than 60, so it can be said that the floor structure according to the present invention.

Also when the

ridge portions

10c and 12 are parallel to the vehicle length direction L, the height h of the convex portion 10 of the floor panel 2 may not be constant. In this case, the “height h” is an average value of the heights h of the convex portions 10. Even in such a floor structure, if C / √h is less than 60 in the portion where the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. When the height h is not constant, C / √h may not be less than 60 over the entire region in the vehicle width direction W. For example, even if the floor panel 2 has a wave shape over the entire region in the vehicle width direction W, the value of C / √h using the average value of the height h and the period C of some sections in the vehicle width direction W If it is less than 60, the mass efficiency of yield strength is improved in the section. Therefore, if attention is paid to the section, the floor structure has a C / √h of less than 60, so it can be said that the floor structure according to the present invention.

Also when the

ridge line portions

10c and 12 are parallel to the vehicle length direction L, the period C and the height h of the convex portion 10 of the floor panel 2 may not be constant. In this case, “period C” is an average value of the periods C of the respective convex portions 10, and “height h” is an average value of the height h of each convex portion 10. Even in such a floor structure, if C / √h is less than 60 in the portion where the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. If the period C and the height h are not constant, C / √h may not be less than 60 over the entire region in the vehicle width direction W. For example, even if the floor panel 2 has a wave shape over the entire area in the vehicle width direction W, C that is the average period of a part of the section in the vehicle width direction W and h that is the average height of the section are used. If the value of C / √h is less than 60, the mass efficiency of yield strength is improved in the section. Therefore, if attention is paid to the section, the floor structure has a C / √h of less than 60, so it can be said that the floor structure according to the present invention.

When the

ridges

10c and 12 are parallel to the vehicle length direction L, the height h of the convex portion 10 of the floor panel 2 may be different depending on the position in the vehicle length direction L. The “height h” in this case is an average value of heights that are different at the position in the vehicle length direction L. Even in such a floor structure, if C / √h is less than 60 in the portion where the wave shape is given, the mass efficiency of yield strength is improved as described in the above embodiment. Also in this case, C / √h is preferably 55 or less, and more preferably 25 or less. In addition, when the height h of the convex portion 10 varies depending on the position in the vehicle length direction L, C / √h may not be less than 60 over the entire region in the vehicle length direction L, and C / only at the longitudinal end portion. If √h is less than 60, the yield strength of the floor panel 2 is improved. In this case, the range in which C / √h is less than 60 may be ¼ or more of the length from the front end to the rear end of the floor panel 2 starting from the end point of the floor panel 2 in the vehicle length direction L. preferable.

<Side collision simulation (A)>
A side impact simulation of the floor structure was conducted assuming a pole side impact. The floor structure of the analysis model used in this simulation is the structure having the flat floor panel shown in FIG. 15 (Comparative Example 1) and the flat floor panel as shown in FIG. This is a structure using a cross-member for joining (comparative example 2) and a corrugated floor panel shown in FIG. Further, regarding the floor structure using the corrugated floor panel, a plurality of analysis models in which the period C and the height h of the convex portion were changed were created and simulations were carried out (Examples 1 to 10). The structure of Example 10 is a structure in which a cross member is joined to a corrugated floor panel. In this simulation, the evaluation is performed by paying attention to the proof stress of the floor panel. Therefore, the side sill is replaced with an elastic plate having a thickness of 6 mm.

Side simulation was performed by placing a 254 mm diameter pole in the center of an elastic plate simulating a side sill and moving the pole by 10 mm at 1 m / s parallel to the vehicle width direction W. The indentation amount (displacement amount) and input load of the pole at that time were recorded, and the input maximum load, that is, the proof stress was measured. Since a material having a strength of 270 to 440 MPa is usually applied to the floor panel, only the floor panel of Comparative Example 2 has a strength of 270 MPa. The other floor panels had a strength of 980 MPa, which was higher than that of a normal one. A material of 590 MPa is usually used for the cross member for pole side collision in Comparative Example 2, but in this simulation, the strength was 980 MPa, which was higher than that of a normal one.

Table 1 below shows the conditions of the analysis model of the side collision simulation and the maximum load ratio (F ₁ / F ₀ ) obtained by normalizing the maximum input load F ₁ of each analysis model with the maximum input load F ₀ of Comparative Example 1. The mass ratio (m ₁ / m ₀ ) obtained by normalizing the mass m ₁ of each analysis model with the mass m ₀ of Comparative Example 1 is also shown.

FIG. 19 shows displacement-load ratio diagrams of Comparative Example 1 and Examples 1 and 2. The load ratio shown in FIG. 19 is a value obtained by normalizing the input load in each analysis model with the maximum input load of Comparative Example 1. As shown in FIG. 19, the input load decreases and changes after the input load reaches the maximum load under any condition. The reason for such transition is that the floor panel undergoes a large deformation after the input load reaches the maximum load. That is, the maximum input load is an input load before the floor panel is largely deformed, and corresponds to a proof stress. Accordingly, FIG. 19 shows that the proof stress of the floor structure of Example 1 is higher than that of Comparative Example 1.

Here, FIG. 20 shows the state of the out-of-plane deformation caused by the simulation of the analysis model of Comparative Example 1. FIG. 21 shows a state of out-of-plane deformation caused by the simulation of the analysis model of the first embodiment. When the pole collides with the side sill, the floor panel receives a compressive load. However, in the case of a flat floor panel as shown in FIG. Deformation has occurred.

On the other hand, as shown in FIG. 21, in the case of the corrugated floor panel of Example 1, the top surface portion 10a and the bottom surface portion 11 of the convex portion are individually deformed out of plane. And the generation | occurrence | production area | region of out-of-plane deformation at the time of seeing as the whole floor panel is narrower than the flat floor panel shown in FIG. The reason why the top surface portion 10a and the bottom surface portion 11 are individually deformed out of plane in this way is that the ridge line portion 10c (FIG. 4) connecting the top surface portion 10a and the side wall portion 10b, and the ridge line connecting the bottom surface portion 11 and the side wall portion 10b. Since the extending direction of the portion 12 (FIG. 4) coincides with the load input direction, a strong resistance is generated against the deformation of the floor panel due to the load input, and each

ridge line portion

10c, 12 serves as a support point at the time of bending deformation. This is because it works. The space between the supporting points is a region where the out-of-plane deformation of the floor panel can occur, but the interval between the supporting points is shortened because the floor panel is corrugated, and the span of bending deformation is changed to a flat floor panel. On the other hand, it becomes shorter. Thereby, in the floor panel of Example 1, resistance to bending deformation is increased, and the proof stress is greater than that of a floor panel that is not corrugated.

Next, when Example 1 and Example 2 are compared in FIG. 19, the maximum load is larger in Example 2 than in Example 1, while the attenuation of the input load after reaching the maximum load is in Example 1. Is smaller. In other words, the maximum load before the large deformation of the floor panel is smaller in the first embodiment than in the second embodiment, but the input load after the large deformation of the floor panel is kept high. Therefore, it can be said that the floor structure of Example 1 is a structure having higher energy absorption performance than that of Example 2, but from the viewpoint of exhibiting high proof strength before large deformation of the floor panel, Is better. This result shows that a floor structure with high energy absorption performance is not necessarily a structure with high yield strength.

FIG. 22 shows the maximum load ratio F ₁ / F obtained by standardizing the convex period C of each analysis model having a corrugated floor panel and the maximum input load F ₁ of each analysis model by the maximum input load F ₀ of Comparative Example 1. The relationship with F ₀ is shown. The plots in FIG. 22 correspond to the results of Comparative Example 5 and Examples 1 to 5 in Table 1 above, and are for the case where h / C is all constant at 0.067. When h / C is constant, the line length of the floor panel in the cross-sectional view as shown in FIG. 4 is constant, and the proof stress can be evaluated under the condition of constant mass.

The result of FIG. 22 shows that the proof stress of the floor panel increases when the period C is made smaller than when the height h of the convex part is made higher under the condition of constant mass. In addition, the plot in the case where the period C in FIG. 22 is 30 mm corresponds to the result of Example 2 of Table 1 above, but according to Table 1 above, the plot is more implemented than Comparative Example 2 which is a floor structure having a cross member. Example 2 has a larger maximum load ratio. From this result, the floor structure of Example 2 shows that the proof stress increases to the extent that the cross member for dealing with the pole side collision can be omitted.

In FIG. 23, C / √h of the convex portion of the floor panel and the maximum load ratio F ₁ / F ₀ of each analysis model are normalized by the mass ratio m ₁ / m ₀ with reference to Comparative Example 1. Show the relationship. The value on the vertical axis in FIG. 23 is the mass efficiency of the yield strength indicating the magnitude of the yield strength per mass, and the higher the value on the vertical axis, the better the balance between the yield strength and the mass.

FIG. 23 shows that the smaller the value of C / √h, the better the mass efficiency. Further, as is clear from FIG. 23 and Table 1 above, even if the floor panel is corrugated, the proof stress mass efficiency may be inferior to that of Comparative Example 1 of a flat floor panel. That is, it is impossible to achieve both yield strength and weight reduction by simply making the floor panel corrugated. In view of the results of this simulation, the floor structure that is superior in mass efficiency of yield strength to Comparative Example 1 is a floor structure in which C / √h is less than 60. Moreover, the mass efficiency of yield strength is greatly improved in the floor structure in which C / √h is 55 or less, and further 25 or less.

In addition, according to the result of Example 10 in Table 1 above, the mass efficiency of yield strength is greatly improved if the cross member is joined to the corrugated floor panel. For this reason, for example, in the case where both improvement in yield strength and weight reduction are prioritized over securing the indoor space and the battery mounting space, it is effective to provide a cross member on the corrugated floor panel.

<Side collision simulation (B)>
Next, a side collision simulation was performed when the floor panel of Example 2 was joined to a side sill via a bracket. The floor structure of the analysis model used in this simulation is a structure in which an L-shaped bracket is arranged on the upper side of the floor panel (inside the vehicle) with the width direction end of the floor panel in contact with the side sill as shown in FIG. Example 11) and a structure (Example 12) in which an L-shaped bracket is arranged between a floor panel and a side sill as shown in FIG. In this simulation, the side sill is replaced with an elastic plate having a thickness of 6 mm in order to pay attention to the influence of the strength of the floor panel due to the difference in the joining position of the L-shaped bracket. The load input conditions are the same as those in the side collision simulation (A) described above.

When the simulation was performed under the above conditions, the maximum input load of Example 11 was 1.56 times the maximum input load of Example 12. That is, when the floor panel and the side sill are joined using the L-shaped bracket, the floor panel is brought into contact with the side sill as shown in FIG. 9 rather than arranging the L-shaped bracket between the floor panel and the side sill as shown in FIG. When the L-shaped bracket is arranged on the floor, the strength as a floor structure is increased.

The present invention can be used as a floor structure attached to a vehicle such as an automobile.

DESCRIPTION OF SYMBOLS 1 Floor structure 2 Floor panel 3 Side sill 4 Side sill outer 4a Side sill outer top surface part 4b Side sill outer vertical wall part 4c Side sill outer flange part 5 Side sill inner 5a Side sill inner top surface part 5b Side sill inner vertical wall part 5c Side sill inner flange part 6 Bracket 6a Bracket 1st wall surface part 6b 2nd wall surface part 7 of bracket 1st wall surface convex part 10 Floor panel convex part 10a Convex part top surface part 10b Convex part side wall part 10c Convex part ridgeline part 11 Bottom face part 12 Ridge Line 13 Flange C of Floor Panel Projection Period H Vehicle Height Direction h Projection Height L Vehicle Length Direction W Vehicle Width Direction

Claims

A floor structure,
A floor panel having a corrugated portion having a ridge portion parallel to the vehicle width direction or the vehicle length direction;
A side sill joined to an end of the floor panel in the vehicle width direction,
The value of C / √h using the period C of the convex portion of the corrugated portion and the height h is less than 60.
In the floor structure according to claim 1,
The value of C / √h is 55 or less.
In the floor structure according to claim 1 or 2,
The ridge line portion is parallel to the vehicle width direction.
In the floor structure according to claim 3,
The floor panel and the side sill are joined via a bracket.
In the floor structure according to claim 4,
The side sill includes a side sill outer and a side sill inner,
The side sill inner has a top surface portion, and a vertical wall portion extending from the top surface portion to the vehicle outer side in the vehicle width direction,
The bracket is L-shaped having a first wall surface portion and a second wall surface portion,
The first wall surface portion is bonded to the floor panel, and the second wall surface portion is bonded to the top surface portion of the side sill inner.
In the floor structure according to claim 5,
An end portion of the floor panel in the vehicle width direction is in contact with the top surface portion of the side sill inner.
The floor structure according to any one of claims 1 to 6,
The floor panel is made of a steel plate having a tensile strength of 780 MPa or more.