Vehicle side sill

Abstract

The present invention provides a side sill for a vehicle, comprising: a first side sill frame; a second side sill frame coupled to the first side sill frame to form a hollow portion together with the first side sill frame; a first reinforcing frame disposed in the hollow portion and having one side joined to the first side sill frame to form a first closed cross section; and a second reinforcing frame disposed in the hollow portion and having one side joined to the first reinforcing frame to form a second closed cross section, wherein the first reinforcing frame and the second reinforcing frame include uneven portions formed continuously along the longitudinal direction of the side sill for the vehicle.

Description

[Technical Field]

[0001] The present invention relates to a side sill for a vehicle. [Background technology]

[0002] It is to be understood that the material set forth in this section is merely provided as background information for the present invention and may not constitute prior art.

[0003] Side sills applied to environmentally friendly vehicles such as electric vehicles protect not only passengers but also the battery located underneath. Because the battery is relatively large compared to other components of the vehicle, the side space of a vehicle equipped with a battery is relatively narrow compared to a vehicle equipped with an internal combustion engine.

[0004] Therefore, the side sills applied to environmentally friendly vehicles must be able to absorb maximum collision energy within a narrow space and have minimum weight to improve the energy efficiency of the environmentally friendly vehicles.

[0005] For this reason, aluminum extrusion materials have been used for the side sills of environmentally friendly vehicles, but there is still a demand for improved collision energy absorption performance and weight reduction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Utility Model Publication No. 20-1998-0043143 Summary of the Invention [Problem to be solved by the invention]

[0007] One aspect of the present invention is to provide a vehicle side sill that can efficiently absorb collision energy and achieve weight reduction.

[0008] SUMMARY OF THE INVENTION One aspect of the present invention is to provide a side sill for a vehicle that can minimize the amount of fluid entering the interior of the vehicle due to a collision and safely protect occupants and a battery, which is a core component. [Means for solving the problem]

[0009] In one aspect to achieve the above object, the present invention provides a vehicle side sill including: a first side sill frame; a second side sill frame coupled to the first side sill frame to form a hollow portion together with the first side sill frame; a first reinforcing frame disposed in the hollow portion and having one side joined to the first side sill frame to form a first closed cross section; and a second reinforcing frame disposed in the hollow portion and having one side joined to the first reinforcing frame to form a second closed cross section, wherein the first reinforcing frame and the second reinforcing frame include uneven portions formed continuously along a length direction of the vehicle side sill.

[0010] At least one of the first side sill frame, the second side sill frame, the first reinforcement frame, and the second reinforcement frame may be made of steel.

[0011] The uneven portion has protruding surfaces and recessed surfaces formed alternately in the longitudinal direction of the side sill, with inclined surfaces formed between the protruding surfaces and the recessed surfaces, and the protruding surfaces, the recessed surfaces, and the inclined surfaces may each be continuously formed on a width-height cross section of the side sill that intersects with the longitudinal direction of the side sill.

[0012] The protruding surface of the first strengthening frame may overlap the protruding surface of the second strengthening frame, and the recessed surface of the first strengthening frame may overlap the recessed surface of the second strengthening frame.

[0013] The recessed surface of the first reinforcement frame may be joined to a first inner surface of the first side sill frame, and the protruding surface of the first reinforcement frame may be spaced apart from the first inner surface of the first side sill frame to form a first buffer space.

[0014] The recessed surface of the first reinforcing frame may have an installation length of 15 to 50 mm in the length direction of the side sill.

[0015] The protruding surface of the second reinforcement frame may be joined to the second inner surface of the second side sill frame, and the recessed surface of the second reinforcement frame may be spaced apart from the second inner surface of the second side sill frame to form a second buffer space.

[0016] The second reinforcing frame may have a protruding surface with an installation length of 15 to 50 mm in the length direction of the side sill.

[0017] The first and second reinforcement frames may have an installation length of 15 to 50 mm such that the protruding surface and the recessed surface have a length in the length direction of the side sill, and a step of 2 to 10 mm may be formed between the protruding surface and the recessed surface.

[0018] The installation width of the first reinforcement frame and the second reinforcement frame may not decrease from the second inner surface of the second side sill frame toward the first inner surface of the first side sill frame.

[0019] The first and second strengthening frames may be formed by bending a single steel plate into multiple stages.

[0020] The first reinforcing frame may have a bending point that protrudes outward from the first closed cross section.

[0021] The bending point of the first reinforcement frame may be formed at a position spaced apart from a first inner surface of the first side sill frame by a distance of about 30 to 70% of an installation width of the first reinforcement frame.

[0022] The first reinforcement frame can include a first section formed by extending toward a first inner surface of the first side sill frame with the bending point as a boundary, and a second section formed by being bent with the bending point as a boundary and extending toward a second inner surface of the second side sill frame, forming a bending angle with the first section within the first closed cross section.

[0023] The first strengthening frame has a bending angle formed inside the first closed cross section, and the bending angle may be in the range of 165 to 175 degrees. [Effects of the Invention]

[0024] According to one embodiment of the present invention, the vehicle side sill has the effect of efficiently absorbing collision energy and achieving a lighter weight.

[0025] According to one embodiment of the present invention, a vehicle side sill has an effect of minimizing the amount of fluid entering the interior of a vehicle due to a collision, and safely protecting passengers and a battery, which is a core component. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a perspective view of a vehicle side sill of a first comparative example to be compared with the vehicle side sill of the present invention. FIG. [Figure 2] 1 is a perspective view of a vehicle side sill according to a first embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along the line II' in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along the line II-II′ of FIG. [Figure 5] FIG. 3 is a cross-sectional view taken along the line III-III′ in FIG. 2. [Figure 6] FIG. 3 is a perspective view of a first reinforcing frame of the vehicle side sill of FIG. 2. [Figure 7] FIG. 3 is a perspective view of a second reinforcing frame of the vehicle side sill of FIG. 2. [Figure 8]3 is a diagram showing the positions of bending points of the vehicle side sill according to the first embodiment of FIG. 2. FIG. [Figure 9a] 10 shows the results of deformation analysis of a vehicle side sill of a first comparative example. [Figure 9b] 10 shows the results of deformation analysis of a vehicle side sill of a first comparative example. [Figure 9c] 10 shows the results of deformation analysis of a vehicle side sill of a first comparative example. [Figure 10a] 4 shows the deformation analysis results of the vehicle side sill of the first embodiment. [Figure 10b] 4 shows the deformation analysis results of the vehicle side sill of the first embodiment. [Figure 10c] 4 shows the deformation analysis results of the vehicle side sill of the first embodiment. [Figure 11] 3 is a load-displacement diagram of a vehicle side sill of a first comparative example in FIG. 1 and a first embodiment in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various different forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those having average knowledge in the art. The shapes and sizes of elements in the drawings may be exaggerated for clarity.

[0028] Hereinafter, the X axis shown in the accompanying drawings is the width direction of the vehicle side sill, the Y axis is the length direction of the vehicle side sill, and the Z axis is the height direction of the vehicle side sill.

[0029] FIG. 1 is a perspective view of a vehicle side sill of a first comparative example to be compared with the vehicle side sill of the present invention.

[0030] The first comparative example differs from the first embodiment described later in that a portion where the uneven portion P is not formed is formed along the length of the side sill.

[0031] In the case of the first comparative example, the deformation of the first reinforcing frame 300 and the second reinforcing frame 400 is not symmetrical in the X-axis direction, and unstable asymmetrical deformation occurs, which can be a major concern in terms of providing stable collision energy absorption performance under various collision environments.

[0032] Hereinafter, the components included in the vehicle side sill according to the first embodiment will be described in detail with reference to FIGS.

[0033] 2 is a perspective view of a vehicle side sill according to a first embodiment of the present invention, FIG. 3 is a cross-sectional view taken along line II' in FIG. 2, FIG. 4 is a cross-sectional view taken along line II-I' in FIG. 2, FIG. 5 is a cross-sectional view taken along line III-II' in FIG. 2, FIG. 6 is a perspective view of a first reinforcing frame 300 of the vehicle side sill of FIG. 2, FIG. 7 is a perspective view of a second reinforcing frame 400 of the vehicle side sill of FIG. 2, and FIG. 8 is a diagram showing the positions of bending points of the vehicle side sill according to the first embodiment of FIG. 2.

[0034] The vehicle side sill according to the first embodiment may include a first side sill frame 100, a second side sill frame 200, a first reinforcing frame 300, and a second reinforcing frame 400.

[0035] The first side sill frame 100 can be disposed on the inner side of the width direction of the side sill in the X-axis direction.

[0036] The second side sill frame 200 may be coupled to the first side sill frame 100 to form a hollow portion S together with the first side sill frame 100. The second side sill frame 200 may be disposed on the outer side of the width direction of the side sill in the X-axis direction. The second side sill frame 200 may be joined to the first side sill frame 100 by welding or the like.

[0037] The first reinforcing frame 300 is disposed in the hollow portion S, and one side thereof is joined to the first side sill frame 100 to form a first closed cross section M1. The first reinforcing frame 300 is joined to the first side sill frame 100 to form the first closed cross section M1, thereby improving the mechanical rigidity of the vehicle side sill.

[0038] The first reinforcing frame 300 can include a first upper flange 310, a pair of first web members 330, and a pair of first lower flanges 350 on the XZ axis cross section of the side sill.

[0039] A first web member 330 may be connected to each of both heightwise ends of the first upper flange 310. The first upper flange 310 may have a serpentine shape in the lengthwise direction of the side sill. Protruding surfaces P1 and recessed surfaces P2 may be alternately formed in the lengthwise direction of the side sill, and an inclined surface P3 may be formed between the protruding surface P1 and the recessed surface P2.

[0040] The first web member 330 may be formed to extend from the first upper flange 310 and extend toward the first inner surface 110 of the first side sill frame 100. The first reinforcing frame 300 may be bent and formed so that the first web member 330 and the first lower flange 350 are arranged to intersect.

[0041] The first lower flange 350 may be joined to the first inner surface 110 of the first side sill frame 100 .

[0042] The second reinforcement frame 400 is disposed in the hollow portion S, and one side thereof is joined to the first reinforcement frame 300 to form a second closed cross section M2. The second reinforcement frame 400 is joined to the first reinforcement frame 300 on one side thereof to form the second closed cross section M2, thereby improving the mechanical rigidity of the vehicle side sill.

[0043] The second reinforcing frame 400 can include a second upper flange 410, a pair of second web members 430, and a pair of second lower flanges 450 on the XZ axis cross section of the side sill.

[0044] The second upper flange 410 may have a serpentine shape in the length direction of the side sill. Protruding surfaces P1 and recessed surfaces P2 may be alternately formed in the length direction of the side sill, and an inclined surface P3 may be formed between the protruding surface P1 and the recessed surface P2. The second upper flange 410 may be flat. This may improve the adhesive strength of the second upper flange 410 when an adhesive or the like is applied to the second upper flange 410 for bonding to the second side sill frame 200, thereby improving the convenience of bonding and assembly operations.

[0045] The second upper flange 410 may have second web members 430 connected to both ends in the height direction.

[0046] The second web member 430 may extend from the second upper flange 410 and may be formed to extend toward the first inner surface 110 of the first side sill frame 100. The second lower flange 450 of the second reinforcement frame 400 may be joined to the first web member 330 of the first reinforcement frame 300.

[0047] The second lower flanges 450 may have a step Q2 formed between the second web members 430, and the spacing between the pair of second lower flanges 450 in the Z-axis direction may be wider than the spacing between the pair of second web members 430 in the Z-axis direction.

[0048] The first reinforcement frame 300 and the second reinforcement frame 400 may include a concave-convex portion P formed continuously along the length direction of the side sill. As an example, the first reinforcement frame 300 and the second reinforcement frame 400 may have the concave-convex portion P formed continuously over the entire length direction of the side sill.

[0049] The uneven portion P has protruding surfaces P1 and recessed surfaces P2 formed alternately in the length direction of the side sill, and an inclined surface P3 may be formed between the protruding surface P1 and the recessed surface P2.

[0050] The vehicle side sill of the present invention can improve rigidity without increasing the thickness of the steel material or the like that constitutes the first reinforcing frame 300 and the second reinforcing frame 400 because the first reinforcing frame 300 and the second reinforcing frame 400 include an uneven portion P.

[0051] The vehicle side sill of the present invention has the effect of being able to stably resist collision energy until the first and second reinforcing frames are sufficiently crushed, since the uneven portions P of the first and second reinforcing frames are continuously formed along the length of the side sill.

[0052] The first reinforcement frame 300 and the second reinforcement frame 400 can have a continuous uneven portion P in the longitudinal direction on a cross section of the side sill, with a protruding surface P1, an inclined surface P3, a recessed surface P2, an inclined surface P3, and a protruding surface P1 repeated.

[0053] For example, the first side sill frame 100 and the first reinforcing frame 300 may be joined by spot welding, the first reinforcing frame 300 and the second reinforcing frame 400 may be joined by laser welding or spot welding, and the second side sill frame 200 and the second reinforcing frame 400 may be joined by adhesive. The first side sill frame 100 and the second side sill frame 200 may be joined by spot welding.

[0054] Of course, various joining methods such as welding or adhesive bonding can be applied to join components such as the first reinforcement frame 300, the second reinforcement frame 400, the first side sill frame 100, and the second side sill frame 200.

[0055] At least one of the first side sill frame 100, the second side sill frame 200, the first reinforcing frame 300, and the second reinforcing frame 400 may be formed by form forming or crush forming a steel plate, which can contribute to reducing manufacturing costs by reducing mold costs, etc.

[0056] The first side sill frame 100, the second side sill frame 200, the first reinforcing frame 300 and the second reinforcing frame 400 may be made of ultra-high strength steel having a tensile strength of 980 MPa or more.

[0057] As an example, the first side sill frame 100 and the second side sill frame 200 may be made of a material including 1470 MART steel, and the first reinforcement frame 300 and the second reinforcement frame 400 may be made of a material including 1180 TRIP steel and 980 DP steel.

[0058] At least one of the first side sill frame 100, the second side sill frame 200, the first reinforcement frame 300, and the second reinforcement frame 400 may be made of steel.

[0059] As an example, the first side sill frame 100, the second side sill frame 200, the first reinforcing frame 300, and the second reinforcing frame 400 may be made of steel, thereby improving the mechanical rigidity of the vehicle side sill.

[0060] The uneven portion P has protruding surfaces P1 and recessed surfaces P2 formed alternately in the length direction of the side sill, and an inclined surface P3 may be formed between the protruding surface P1 and the recessed surface P2.

[0061] The protruding surface P1, the recessed surface P2, and the inclined surface P3 may be formed continuously on a cross section (XZ-axis cross section) of the side sill in the width direction-height direction that intersects with the length direction of the side sill. As an example, the protruding surface P1, the recessed surface P2, and the inclined surface P3 may be formed continuously over the entire cross section (XZ-axis cross section) of the side sill in the width direction-height direction.

[0062] The protruding surface P1, the recessed surface P2, and the inclined surface P3 can each include a "U-shaped" or "V-shaped" cross-sectional portion that is open toward the first inner surface 110 of the first side sill frame 100 on a width-height cross-section (XZ axis cross-section) of the side sill.

[0063] In this case, the size of the cross section in the width direction-height direction (XZ axis cross section) can become smaller toward the protruding surface P1, the inclined surface P3, and the recessed surface P2.

[0064] The vehicle side sill of the present invention has the advantage that the protruding surface P1, the recessed surface P2, and the inclined surface P3 of the first and second reinforcing frames are continuously formed on a cross section (XZ-axis cross section) of the side sill in the width-height direction that intersects with the longitudinal direction of the side sill, thereby enabling the first and second reinforcing frames to stably resist collision energy until they are sufficiently crushed.

[0065] The protruding surface P1 of the first reinforcement frame 300 can overlap the protruding surface P1 of the second reinforcement frame 400, and the recessed surface P2 of the first reinforcement frame 300 can overlap the recessed surface P2 of the second reinforcement frame 400.

[0066] The protruding surfaces P1 of the first reinforcement frame 300 and the second reinforcement frame 400 overlap each other, and the recessed surfaces P2 of the first reinforcement frame 300 and the second reinforcement frame 400 overlap each other, which has the effect of improving the bonding strength between the first reinforcement frame 300 and the second reinforcement frame 400.

[0067] Since the protruding surfaces P1 of the first reinforcing frame 300 and the second reinforcing frame 400 overlap each other and the recessed surfaces P2 of the first reinforcing frame 300 and the second reinforcing frame 400 overlap each other, the joining position of the first reinforcing frame 300 and the second reinforcing frame 400 can be naturally guided, which has the effect of improving the workability of the worker.

[0068] The recessed surface P2 of the first reinforcement frame 300 is joined to the first inner surface 110 of the first side sill frame 100, and the protruding surface P1 of the first reinforcement frame 300 is spaced apart from the first inner surface 110 of the first side sill frame 100 to form a first buffer space R1.

[0069] The recessed surface P2 of the first reinforcing frame 300 may have an installation length Q1 of 15 to 50 mm in the length direction of the side sill.

[0070] The protruding surface P1 of the second reinforcement frame 400 is joined to the second inner surface 210 of the second side sill frame 200, and the recessed surface P2 of the second reinforcement frame 400 is spaced apart from the second inner surface 210 of the second side sill frame 200 to form a second buffer space R2.

[0071] The second reinforcing frame 400 may have an installation length Q1 of 15 to 50 mm in the length direction of the side sill, such that the protruding surface P1 of the second reinforcing frame 400 is 15 to 50 mm.

[0072] The recessed surface P2 of the first reinforcement frame 300 can be joined to the first inner surface 110 of the first side sill frame 100, and the protruding surface P1 of the second reinforcement frame 400 can be joined to the second inner surface 210 of the second side sill frame 200.

[0073] If the recessed surface P2 of the first reinforcing frame 300 and the protruding surface P1 of the second reinforcing frame 400 have an installation length Q1 of less than 15 mm in the longitudinal direction of the side sill, the matching surface for joining the recessed surface P2 and the first inner surface 110 becomes small, which may make joining by laser welding, spot welding, etc. difficult.

[0074] Furthermore, if the recessed surface P2 of the first reinforcement frame 300 and the protruding surface P1 of the second reinforcement frame 400 have an installation length Q1 of more than 50 mm in the longitudinal direction of the side sill, there is a problem in that the uneven portion P cannot fully perform its role of improving rigidity without increasing the thickness of the steel material, etc., that constitutes the first reinforcement frame 300 and the second reinforcement frame 400.

[0075] The first reinforcement frame 300 and the second reinforcement frame 400 have a protruding surface P1 and a recessed surface P2 with an installation length Q1 of 15 to 50 mm in the longitudinal direction of the side sill, and a step Q2 of 2 to 10 mm may be formed between the protruding surface P1 and the recessed surface P2.

[0076] The recessed surface P2 of the first reinforcement frame 300 may be joined to the first inner surface 110 of the first side sill frame 100. The protruding surface P1 of the second reinforcement frame 400 may be joined to the second inner surface 210 of the second side sill frame 200.

[0077] If the first reinforcing frame 300 and the second reinforcing frame 400 have an installation length Q1 of less than 15 mm in the longitudinal direction of the side sill, the matching surface for joining the recessed surface P2 and the first inner surface 110 becomes small, which may make joining by laser welding, spot welding, etc. difficult.

[0078] In addition, when the protruding surface P1 and the recessed surface P2 of the first reinforcement frame 300 and the second reinforcement frame 400 have an installation length of more than 50 mm in the longitudinal direction of the side sill, there is a problem in that the uneven portion P cannot fully perform its role of improving rigidity without increasing the thickness of the steel material, etc., that constitutes the first reinforcement frame 300 and the second reinforcement frame 400.

[0079] The first and second reinforcing frames 300 and 400 have a problem in that if the step Q2 between the protruding surface P1 and the recessed surface P2 is less than 2 mm, the uneven portion P cannot properly perform its role of improving rigidity without increasing the thickness of the steel material, etc., that constitutes the first and second reinforcing frames 300 and 400.

[0080] If the step Q2 between the protruding surface P1 and the recessed surface P2 of the first reinforcement frame 300 and the second reinforcement frame 400 exceeds 10 mm, it may become difficult to form the first reinforcement frame 300 and the second reinforcement frame 400 using high-strength steel of 980 MPa or more, or a forming problem may arise in which forming may become impossible.

[0081] The installation width of the first reinforcing frame 300 and the second reinforcing frame 400 does not need to decrease as it moves from the second inner surface 210 of the second side sill frame 200 toward the first inner surface 110 of the first side sill frame 100 .

[0082] For example, the installation width of the first reinforcement frame 300 and the second reinforcement frame 400 may increase from the first inner surface 110 of the first side sill frame 100 toward the second inner surface 210 of the second side sill frame 200 .

[0083] As another example, the first reinforcement frame 300 and the second reinforcement frame 400 may have an installation width that increases from the first inner surface 110 of the first side sill frame 100 toward the second inner surface 210 of the second side sill frame 200, or may have at least the same installation width but not decrease.

[0084] An impact can be applied in the X-axis direction on the second side sill frame 200 side, and if the installation width of the first and second reinforcing frames increases in the direction away from the point where the impact is applied, the first and second reinforcing frames can easily compress and deform in the direction where the impact is applied, resulting in excellent load-bearing performance.

[0085] The first and second strengthening frames 300 and 400 may be formed by bending a single steel plate into multiple stages.

[0086] The first and second reinforcing frames can be formed by bending a single steel plate in multiple stages. By forming the first reinforcing frame 300 by bending a single steel plate in multiple stages, the first and second reinforcing frames made of a single steel plate behave as a single unit, improving the mechanical rigidity of the vehicle side sill.

[0087] The first strengthening frame 300 may be formed by bending a first steel plate having a first thickness into multiple stages.

[0088] The protruding surface P1 and the recessed surface P2 of the first reinforcement frame 300 have an installation thickness in the longitudinal direction of the side sill that is 10.7 to 35.7 times the first thickness, and the first reinforcement frame 300 may have a step between the protruding surface P1 and the recessed surface P2 that is 1.4 to 7.1 times the first thickness.

[0089] For example, the first strengthening frame 300 may be formed by bending a 1.4 mm steel plate in multiple stages. The first strengthening frame 300 may have a protruding surface P1 and a recessed surface P2 each having an installation length of 15 to 50 mm in the length direction of the side sill, and a step of 2 to 10 mm may be formed between the protruding surface P1 and the recessed surface P2.

[0090] The second strengthening frame 400 may be formed by bending a second steel plate having a second thickness in multiple stages.

[0091] The protruding surface P1 and the recessed surface P2 of the second reinforcement frame 400 have an installation thickness in the longitudinal direction of the side sill that is 12.5 to 41.7 times the second thickness, and the second reinforcement frame 400 may have a step between the protruding surface P1 and the recessed surface P2 that is 1.7 to 8.3 times the second thickness.

[0092] For example, the second reinforcing frame 400 may be formed by bending a 1.2 mm steel plate in multiple stages. The second reinforcing frame 400 may have a protruding surface P1 and a recessed surface P2 each having an installation length of 15 to 50 mm in the length direction of the side sill, and a step of 2 to 10 mm may be formed between the protruding surface P1 and the recessed surface P2.

[0093] The first reinforcing frame 300 may have bending points 370 that protrude outward (in the Z-axis direction) at the first closed cross section M1.

[0094] No. The bending point 370 of the first reinforcing frame 300 may be formed at a position spaced apart from the first inner surface 110 of the first side sill frame 100 by a distance of 30 to 70% of the installation width T of the first reinforcing frame 300 .

[0095] If the position of the bending point 370 is less than 30% or more than 70% of the installation width T of the first reinforcement frame 300 from the first inner surface 110 of the first side sill frame 100, bending guidance will not be performed well at the bending point 370 of the first reinforcement frame 300, and normal crushing may not occur.

[0096] If normal crushing does not occur in the first reinforcing frame 300, tilting deformation may occur, as in the comparative example described above, resulting in a problem of insufficient load-bearing performance. Furthermore, this may be a major concern in terms of the vehicle side sill's ability to stably absorb collision energy under various collision environments.

[0097] The first reinforcing frame 300 may include a first section 331 and a second section 333 .

[0098] The first section 331 may be formed to extend toward the first inner surface 110 of the first side sill frame 100, with the bending point 370 as a boundary. The second section 333 may be bent with the bending point 370 as a boundary, and extend toward the second inner surface 210 of the second side sill frame 200, and may form a bending angle 390 with the first section 331 inside the first closed cross section M1.

[0099] A bending point 370 may be provided at the boundary between the first section 331 and the second section 333. The first reinforcement frame 300 may be bent such that the first section 331 and the second section 333 are bent with the bending point 370 as the boundary.

[0100] A bend angle 390 is formed within the first closed cross section M1 and may be comprised of less than 180 degrees.

[0101] The first strengthening frame 300 has a bending angle 390 formed inside the first closed cross section M1, and the bending angle 390 may be in the range of 165 to 175 degrees. The angle θ formed between the extension line of the first section 331 and the extension line of the second section 333 may be in the range of 5 to 15 degrees.

[0102] The first section 331 and the second section 333 are bent with respect to the bending point 370, so that a bending angle 390 may be formed inside the first closed cross section M1.

[0103] The first strengthening frame 300 has a bending angle 390 in the range of 165 to 175 degrees, so that bending can be stably induced at the bending point 370 while ensuring sufficient rigidity of the first strengthening frame 300.

[0104] If the bending angle 390 of the first reinforcement frame 300 is less than 165 degrees, bending can be induced well at the bending point 370. However, if bending is induced too easily at the bending point 370 of the first reinforcement frame 300, the first reinforcement frame 300 may bend at the bending point 370 before it can achieve its designed load-bearing capacity, which may result in a reduction in its load-bearing capacity.

[0105] The first reinforcing frame 300 may not collapse normally, but may be deformed to tilt as in the comparative example, resulting in insufficient load-bearing capacity. This may also be a major concern in preventing the vehicle side sill from stably absorbing collision energy under various collision conditions.

[0106] If the bending angle 390 exceeds 175 degrees, bending guidance at the bending point 370 may not be performed well, and normal crushing may not occur.

[0107] The first reinforcement frame 300 may not collapse normally, but may be deformed to tilt as in the comparative example, resulting in a problem that the designed load capacity cannot be achieved.

[0108] Below, the results of deformation analysis of the vehicle side sill of the first comparative example and the vehicle side sill of the first embodiment will be described with reference to FIGS. 9a to 10c.

[0109] 9a to 9c show the deformation analysis results of the vehicle side sill of the first comparative example.

[0110] FIG. 9a shows the deformation analysis results for the first comparative example in the early stage of the collision, FIG. 9b shows the deformation analysis results for the first comparative example in the middle stage of the collision, and FIG. 9c shows the deformation analysis results for the first comparative example in the later stage of the collision.

[0111] In the first comparative example, it can be seen that the second side sill frame 200 and the second reinforcing frame 400 are compressively deformed in the X-axis direction at the initial stage of the collision.

[0112] In the first comparative example, it can be seen that in the middle and later stages of the collision, the deformation of the first reinforcing frame 300 and the second reinforcing frame 400 is not symmetrical in the X-axis direction, but unstable asymmetrical deformation occurs.

[0113] This poses a problem in that it can be a major factor in terms of achieving stable collision energy absorption performance under various collision environments.

[0114] 10a to 10c show the results of deformation analysis of the vehicle side sill of the first embodiment.

[0115] FIG. 10a shows the deformation analysis results for the first embodiment at the early stage of the collision, FIG. 10b shows the deformation analysis results for the first embodiment at the middle stage of the collision, and FIG. 10c shows the deformation analysis results for the first embodiment at the late stage of the collision.

[0116] In the first embodiment, it can be seen that the second side sill frame 200 and the second reinforcing frame 400 are compressively deformed in the X-axis direction at the initial stage of a collision.

[0117] In the first embodiment, it can be seen that the deformation of the first reinforcing frame 300 and the second reinforcing frame 400 occurs in a symmetrical shape in the X-axis direction during the middle and later stages of the collision, resulting in stable crush deformation.

[0118] It can be seen that the first and second strengthening frames 300 and 400 are uniformly compressed in the X-axis direction without deformation being biased to one side.

[0119] FIG. 11 is a load-displacement diagram of the vehicle side sill of the first comparative example in FIG. 1 and the first embodiment in FIG.

[0120] The load-displacement value of the vehicle side sill of the first comparative example in FIG. 1 is indicated by a first value L1, and the load-displacement value of the vehicle side sill of the first embodiment in FIG. 2 is indicated by a second value L2.

[0121] First Value L1 and the second value L2 2, it can be seen that the displacement of the vehicle side sill of the first embodiment in FIG. 2 is relatively smaller than that of the vehicle side sill of the first comparative example in FIG. 1 under the same load.

[0122] In the case of the first value L1, the impact absorption capacity drops sharply at a displacement of 90 mm or more, which corresponds to the later stage of the collision, whereas in the case of the second value L2, the impact is absorbed stably even in the later stage of the collision.

[0123] Specifically, the internal energy of the vehicle side sill of the first comparative example is 47.9 KJ, the weight of the vehicle side sill of the first comparative example is 18.7 kg, the internal energy of the vehicle side sill of the first embodiment is 49.3 KJ, and the weight of the vehicle side sill of the first embodiment is 18.9 kg.

[0124] In other words, the vehicle side sill of the first comparative example has an internal energy ratio per kg of 2.56 (KJ / kg), while the vehicle side sill of the first example has an internal energy ratio per kg of 2.62 (KJ / kg), which shows that the first example has a higher internal energy ratio per kg than the first comparative example and therefore has better load performance.

[0125] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it is obvious to those skilled in the art that various modifications and variations are possible within the scope that does not deviate from the technical idea of ​​the present invention described in the claims. [Explanation of symbols]

[0126] 100: First side sill frame 110: First inner surface 200: Second side sill frame 210: Second inner surface 300: First reinforced frame 310: First upper flange 330: First web member 331: First Section 333:Second Section 350: First lower flange 370: Bending point 390: Bending angle 400: Second reinforced frame 410: Second upper flange 430: Second web member 450: Second lower flange M1: 1st closed section M2: 2nd closed section P: Uneven part P1:Protruding surface P2: Concave surface P3: Inclined surface Q1: Installation thickness Q2: Steps R1: 1st buffer space R2: Second buffer space S: Hollow part T: Installation width of the first reinforcement frame U: Position of bending point

Claims

1. a first side sill frame; a second side sill frame coupled to the first side sill frame to form a hollow portion together with the first side sill frame; a first reinforcing frame disposed in the hollow portion, one side of which is joined to the first side sill frame to form a first closed cross section; a second reinforcement frame disposed in the hollow portion, one side of which is joined to the first reinforcement frame to form a second closed cross section; The first reinforcement frame and the second reinforcement frame are The side sill for a vehicle includes a concave-convex portion formed continuously along the length direction thereof, The uneven portion is The side sill for a vehicle has protruding surfaces and recessed surfaces alternately formed in a longitudinal direction thereof, and an inclined surface is formed between the protruding surfaces and the recessed surfaces, The protruding surface, the recessed surface, and the inclined surface are each formed continuously on a cross section of the vehicle side sill in a width direction-height direction intersecting with the length direction of the vehicle side sill, the recessed surface of the first reinforcing frame is joined to a first inner surface of the first side sill frame, The protruding surface of the first reinforcing frame is spaced apart from a first inner surface of the first side sill frame to form a first buffer space.

2. The vehicle side sill according to claim 1 , wherein at least one of the first side sill frame, the second side sill frame, the first reinforcement frame, and the second reinforcement frame is made of steel.

3. 2. The vehicle side sill according to claim 1, wherein the protruding surface of the first reinforcement frame overlaps the protruding surface of the second reinforcement frame, and the recessed surface of the first reinforcement frame overlaps the recessed surface of the second reinforcement frame.

4. 2. The vehicle side sill according to claim 1, wherein the recessed surface of the first reinforcement frame has an installation length of 15 to 50 mm in the length direction of the vehicle side sill.

5. A first side sill frame; a second side sill frame coupled to the first side sill frame to form a hollow portion together with the first side sill frame; a first reinforcing frame disposed in the hollow portion, one side of which is joined to the first side sill frame to form a first closed cross section; a second reinforcement frame disposed in the hollow portion, one side of which is joined to the first reinforcement frame to form a second closed cross section; The first reinforcement frame and the second reinforcement frame are The side sill for a vehicle includes a concave-convex portion formed continuously along the length direction thereof, The uneven portion is The side sill for a vehicle has protruding surfaces and recessed surfaces alternately formed in a longitudinal direction thereof, and an inclined surface is formed between the protruding surfaces and the recessed surfaces, The protruding surface, the recessed surface, and the inclined surface are each formed continuously on a cross section of the vehicle side sill in a width direction-height direction intersecting with the length direction of the vehicle side sill, the protruding surface of the second reinforcing frame is joined to a second inner surface of the second side sill frame, The recessed surface of the second reinforcement frame is spaced apart from a second inner surface of the second side sill frame to form a second buffer space.

6. The vehicle side sill according to claim 5, wherein the second reinforcing frame has a protruding surface with an installation length of 15 to 50 mm in the length direction of the vehicle side sill.

7. The first reinforcement frame and the second reinforcement frame are The protruding surface and the recessed surface have an installation length of 15 to 50 mm in the length direction of the vehicle side sill, 2. The vehicle side sill according to claim 1, wherein a step of 2 to 10 mm is formed between the protruding surface and the recessed surface.

8. The installation width of the first reinforcement frame and the installation width of the second reinforcement frame are: The vehicle side sill according to claim 1, wherein the installation width does not decrease from the second inner surface of the second side sill frame toward the first inner surface of the first side sill frame.

9. The first reinforcement frame and the second reinforcement frame are 2. The vehicle side sill according to claim 1, wherein the side sill is formed by bending a single steel plate into multiple stages.

10. The first reinforcement frame is a first upper flange; a pair of first web members respectively connected to both side ends of the first upper flange in a height direction and extending toward a first inner surface of the first side sill frame; a pair of first lower flanges joined to the first inner surface; The first web member of the first reinforcing frame comprises: The vehicle side sill according to claim 1 , wherein the first closed cross section has a bending point that protrudes outward.

11. The first reinforcing frame is 11. The vehicle side sill according to claim 10, wherein the bending point is formed at a position spaced apart from the first inner surface of the first side sill frame by a distance of 30 to 70% of the installation width of the first reinforcement frame.

12. The first reinforcing frame is a first section formed by extending in a direction toward a first inner surface of the first side sill frame with the bending point as a boundary; a second section that is bent with the bending point as a boundary and extends toward a second inner surface of the second side sill frame, and that forms a bending angle with the first section within the first closed cross section.

13. The first reinforcing frame is 13. The vehicle side sill according to claim 12, wherein the bending angle is formed inside the first closed cross section, and the bending angle has a range of 165 to 175 degrees.

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