Vehicle subframe

Abstract

The present invention provides a vehicle subframe (1), wherein the first side beam has a first extension portion that deflects and extends toward the outside of one side of the width direction as it goes from the rear side to the front side, the second side beam has a second extension portion that deflects and extends toward the outside of the other side of the width direction as it goes from the rear side to the front side, and the vehicle subframe also has a second cross beam that is opposite to the first cross beam on the front side and connects a portion of the first extension portion that is deflected more toward the outside of the one side of the width direction and a portion of the second extension portion that is deflected more toward the outside of the other side of the width direction.

Description

Technical Field

[0001] The present invention relates to a vehicle subframe, and more particularly to a vehicle subframe that is mounted on a vehicle such as an automobile and supports a drive source such as an internal combustion engine or an electric motor, a suspension arm, and the like. Background Art

[0002] In recent years, various external force applying components such as suspension arms, stabilizers and other suspension-related components, steering-related components such as steering gear boxes, and mounting-related components of drive source / gear mechanism systems are mounted on subframes mounted on vehicles such as automobiles.

[0003] Therefore, it is required that the subframe be mounted on the vehicle body in a manner that its strength and rigidity are further increased while improving its productivity and the like.

[0004] Furthermore, in a typical frontal collision of a vehicle to which the subframe is mounted, the subframe is required to deform in a desired deformation mode, that is, to exhibit a desired collision performance, in order to absorb a portion of the kinetic energy received by the vehicle during the collision.

[0005] In this situation, Japanese Patent Gazette No. 2001-30949 relates to the front body structure of a vehicle, and discloses that a suspension cross beam 20 comprises: a pair of left and right front-rear direction members 21, 22, which extend in the front-rear direction of the vehicle and have a bending portion in the middle; a connecting member 23, which extends in the vehicle width direction at the front ends of the front-rear direction members 21, 22 to connect the front ends of each front-rear direction member; and a suspension arm support portion 24, which is respectively arranged on the side of each front-rear direction member 21, 22. The suspension cross beam 20 is composed of a butt-welded material with thick plates 21A, 22A in the front portion, thin plates 21B, 22B in the middle portion, and thick plates 21C, 22C in the rear portion. Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, according to the research of the inventors, in the structure of Japanese Patent Gazette No. 2001-30949, by setting intermediate thin plate portions 21B, 22B on a pair of left and right front-rear directional members 21, 22, and connecting the front ends of the front-rear directional members with a connecting member 23, it is intended that in an offset collision, the front-rear directional member 21 on the collision side absorbs the impact energy in the front-rear direction, and the front-rear directional member 22 on the other side absorbs the impact energy converted in the vehicle width direction. However, there is no disclosure or revelation of a specific structure for suppressing unnecessary deformation during a vehicle collision and reliably deforming fragile portions such as the intermediate thin plate portions 21B, 22B, thereby exerting the desired collision performance, when a pair of side beams such as the front-rear directional members 21, 22 are connected by a cross beam that can set a suspension arm support portion and an intermediate vehicle body mounting portion.

[0008] The present invention has been completed after the above research, and an object of the present invention is to provide a vehicle subframe which can suppress unnecessary deformation of a side member during a frontal collision of the vehicle and can thereby exhibit a desired collision performance.

[0009] Means for solving problems

[0010] In order to achieve the above-mentioned object, a first aspect of the present invention is a vehicle subframe, which is installed on a vehicle body and comprises: a first side beam, which is extended in the front-rear direction of the vehicle body and is provided with a first front vehicle body mounting portion on the front side in the front-rear direction and a first rear vehicle body mounting portion on the rear side in the front-rear direction; a second side beam, which is extended in the front-rear direction of the vehicle body and is arranged opposite to the first side beam in the width direction of the vehicle body and is provided with a second front vehicle body mounting portion on the front side and a second rear vehicle body mounting portion on the rear side; and a first cross beam, which is extended in the width direction and connects the first side beam and the second side beam. The first side beam has a first extension portion that deflects and extends toward the outside of one side of the width direction as it goes from the rear side to the front side, and the second side beam has a second extension portion that deflects and extends toward the outside of the other side of the width direction as it goes from the rear side to the front side, and the vehicle subframe also includes a second cross beam that is opposite to the first cross beam on the front side and connects a portion of the first extension portion that is deflected more toward the outside of the one side of the width direction and a portion of the second extension portion that is deflected more toward the outside of the other side of the width direction.

[0011] In addition, a second aspect of the present invention is that, based on the first aspect, a connecting portion of the second cross beam connected to the first side beam has a first expansion portion, and the length of the first expansion portion in the front-to-back direction increases as it goes to the one side of the width direction, and a connecting portion of the second cross beam connected to the second side beam has a second expansion portion, and the length of the second expansion portion in the front-to-back direction increases as it goes to the other side of the width direction.

[0012] In addition, the third aspect of the present invention is that, on the basis of the first or second aspect, in the first expansion portion, at least one of the wall portion on the front direction side and the wall portion on the rear direction side of the first expansion portion extends in the front-to-back direction, and in the second expansion portion, at least one of the wall portion on the front direction side and the wall portion on the rear direction side of the second expansion portion extends in the front-to-back direction.

[0013] In addition, a fourth aspect of the present invention is that, on the basis of any one of the first to third aspects, it further comprises: a first vehicle body mounting component, which is protrudingly arranged on one side in the width direction toward the upper side in the up-down direction of the vehicle body relative to the first side beam and the cross beam, and is provided with a first middle vehicle body mounting portion between the first front vehicle body mounting portion and the first rear vehicle body mounting portion in the front-rear direction; and a second vehicle body mounting component, which is protrudingly arranged on the other side in the width direction toward the upper side relative to the second side beam and the cross beam, and is provided with a second middle vehicle body mounting portion between the second front vehicle body mounting portion and the second rear vehicle body mounting portion in the front-rear direction, the connecting portion of the second cross beam connected to the first side beam being configured to be closer to the first front vehicle body mounting portion than the first middle vehicle body mounting portion, and the connecting portion of the second cross beam connected to the second side beam being configured to be closer to the second front vehicle body mounting portion than the second middle vehicle body mounting portion.

[0014] Effects of the Invention

[0015] According to the structure of the first aspect of the present invention, the first side beam has a first extension portion that deflects and extends toward the outer side of one side in the width direction as it goes from the rear side to the front side, and the second side beam has a second extension portion that deflects and extends toward the outer side of the other side in the width direction as it goes from the rear side to the front side, and also includes a second cross beam, which is opposite to the first cross beam on the front side and connects a portion of the first extension portion that deflects more toward the outer side of the one side in the width direction and a portion of the second extension portion that deflects more toward the outer side of the other side in the width direction. Therefore, in a so-called offset collision, when a frontal collision load that deflects to one side of the vehicle to the left or right is applied to one of the first side beam and the second side beam, unnecessary deformation of the side beam of the one side toward the outer side in the width direction can be suppressed, and the collision load can be transmitted to the other side beam to be dispersed.

[0016] In addition, according to the structure of the second aspect of the present invention, the connecting portion of the second cross beam connected to the first side beam has a first enlarged portion, and the length of the first enlarged portion in the front-to-rear direction increases as it goes to the one side in the width direction, and the connecting portion of the second cross beam connected to the second side beam has a second enlarged portion, and the length of the second enlarged portion in the front-to-rear direction increases as it goes to the other side in the width direction. As a result, unnecessary deformation of the side beam to which the collision load is applied toward the outer side in the width direction can be reliably suppressed, and the collision load can be reliably dispersed.

[0017] In addition, according to the structure of the third aspect of the present invention, in the first enlarged portion, at least one of the wall portion on the front direction side and the wall portion on the rear direction side of the first enlarged portion extends in the front-to-rear direction, and in the second enlarged portion, at least one of the wall portion on the front direction side and the wall portion on the rear direction side of the second enlarged portion extends in the front-to-rear direction. As a result, the side beam can be reliably connected in accordance with the freedom of layout around the subframe, unnecessary deformation of the side beam to which the collision load is applied toward the outside in the width direction can be more reliably suppressed, and the collision load can be more reliably dispersed.

[0018] In addition, according to the structure of the fourth aspect of the present invention, it also includes: a first vehicle body mounting component, which is protruded on one side in the width direction relative to the first side beam and the cross beam toward the upper side in the up-down direction of the vehicle body, and a first middle vehicle body mounting portion is set between the first front vehicle body mounting portion and the first rear vehicle body mounting portion in the front-rear direction; and a second vehicle body mounting component, which is protruded on the other side in the width direction relative to the second side beam and the cross beam toward the upper side, and a second middle vehicle body mounting portion is set between the second front vehicle body mounting portion and the second rear vehicle body mounting portion in the front-rear direction, the connecting portion of the second cross beam connected to the first side beam is configured to be closer to the first front vehicle body mounting portion than the first middle vehicle body mounting portion, and the connecting portion of the second cross beam connected to the second side beam is configured to be closer to the second front vehicle body mounting portion than the second middle vehicle body mounting portion, thereby improving the mounting strength and rigidity of the subframe to the vehicle body, further suppressing unnecessary deformation of the side beam toward the outside in the width direction, and further dispersing the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a plan view showing the structure of a vehicle subframe in the embodiment of the present invention.

[0020] Figure 2 It is a bottom view showing the structure of the vehicle subframe according to the present embodiment.

[0021] Figure 3 It is a left side view showing the structure of the vehicle subframe according to the present embodiment.

[0022] Figure 4A yes Figure 1 AA section view, Figure 4B yes Figure 1 BB cross-sectional view.

[0023] Figure 5A yes Figure 3 CC cross-sectional view, Figure 5B yes Figure 3FF cross-sectional view, Figure 5C yes Figure 3 GG cross-sectional view.

[0024] Fig. 6A 1 is a left partial enlarged side view showing the structure of a crash box of a vehicle subframe according to the present embodiment, Figure 6B 1 is a left partial enlarged side view showing the structure of the side beam of the vehicle subframe of the present embodiment, and the position is equivalent to Figure 3 .

[0025] Fig. 7A The vehicle subframe of the present embodiment is deformed by a collision load applied from the front side to the rear side during a frontal collision of the vehicle. Figure 3 A rather schematic left side view, Figure 7B The diagram schematically shows how the load applied to the vehicle subframe of the present embodiment changes with respect to the deformation amount in the front-rear direction of the vehicle subframe when the vehicle subframe deforms due to a collision load applied from the front to the rear during a frontal collision of the vehicle.

[0026] Fig. 8A is a partial top view of a vehicle subframe in this embodiment, Figure 8B It is a partial bottom view of the vehicle subframe in the present embodiment.

[0027] Explanation of symbols

[0028] 1: Subframe;

[0029] 10: beam;

[0030] 12: lateral upper part;

[0031] 14: upper wall;

[0032] 16: anterior longitudinal wall;

[0033] 18: posterior longitudinal wall;

[0034] 20: extension;

[0035] 21: through hole;

[0036] 22: lateral lower part;

[0037] 24: Bottom wall;

[0038] 26: anterior longitudinal wall;

[0039] 28: posterior longitudinal wall;

[0040] 30: extension;

[0041] 31: through hole;

[0042] 35: left opening end;

[0043] 36: left supporting member;

[0044] 38: longitudinal wall;

[0045] 40: flange portion;

[0046] 41: through hole;

[0047] 42: nut;

[0048] 43: through hole;

[0049] 45: right opening end;

[0050] 46: right supporting member;

[0051] 48: longitudinal wall;

[0052] 50: flange portion;

[0053] 51: through hole;

[0054] 52: nut;

[0055] 53: through hole;

[0056] 60: left mounting component;

[0057] 62: left rear part;

[0058] 63: wall;

[0059] 64: left front part;

[0060] 65: Bottom wall;

[0061] 66: anterior longitudinal wall;

[0062] 67: Left longitudinal wall;

[0063] 68: inclined wall portion;

[0064] 69: upper wall;

[0065] 70: through hole;

[0066] 80: right mounting part;

[0067] 82: right rear part;

[0068] 83: wall;

[0069] 84: right front part;

[0070] 85: Bottom wall;

[0071] 86: anterior longitudinal wall;

[0072] 87: right longitudinal wall;

[0073] 88: inclined wall portion;

[0074] 89: upper wall;

[0075] 90: through hole;

[0076] 110: left beam;

[0077] 112: upper left component;

[0078] 114: upper wall;

[0079] 116: left side wall;

[0080] 118: right side wall;

[0081] 119, 120: through holes;

[0082] 121: upper left deflection unit;

[0083] 121a: upper left deflection increasing portion;

[0084] 122: inclined portion;

[0085] 123: anterior curvature;

[0086] 124: posterior curvature;

[0087] 126: concave part;

[0088] 132: lower left part;

[0089] 134: Bottom wall;

[0090] 136: left side wall;

[0091] 138: right side wall;

[0092] 139, 140: through holes;

[0093] 141: left lower deflection unit;

[0094] 141a: lower left deflection increase portion;

[0095] 142: inclined portion;

[0096] 143: anterior curvature;

[0097] 144: posterior curvature;

[0098] 145: Steeply inclined part;

[0099] 146: concave part;

[0100] 147, 148 and 149: through holes;

[0101] 150: right beam;

[0102] 152: upper right part;

[0103] 154: upper wall;

[0104] 156: right side wall;

[0105] 158: left side wall;

[0106] 159, 160: through holes;

[0107] 161: upper right deflection unit;

[0108] 161a: upper right deflection increase portion;

[0109] 162: inclined portion;

[0110] 163: anterior curvature;

[0111] 164: posterior curvature;

[0112] 166: concave part;

[0113] 172: lower right part;

[0114] 174: Bottom wall;

[0115] 176: right side wall;

[0116] 178: left side wall;

[0117] 179, 180: through holes;

[0118] 181: right lower deflection unit;

[0119] 181a: right lower deflection increase portion;

[0120] 182: inclined portion;

[0121] 183: anterior curvature;

[0122] 184: posterior curvature;

[0123] 185: Steeply inclined part;

[0124] 186: concave part;

[0125] 187, 188 and 189: through holes;

[0126] 210: rear upper beam;

[0127] 211, 212: nuts;

[0128] 213, 214, 215, 216, 217: through holes;

[0129] 218: groove;

[0130] 225, 226, 227: through holes;

[0131] 230: rear lower beam;

[0132] 233, 234: through holes;

[0133] 240: front crossbar;

[0134] 242: lateral upper part;

[0135] 244: upper wall;

[0136] 246: anterior longitudinal wall;

[0137] 248: posterior longitudinal wall;

[0138] 249: through hole;

[0139] 252: lateral lower part;

[0140] 254: Bottom wall;

[0141] 256: anterior longitudinal wall;

[0142] 258: posterior longitudinal wall;

[0143] 259: through hole;

[0144] 260: left collision energy absorption box;

[0145] 261: fixed parts;

[0146] 262: upper left component;

[0147] 264: upper wall;

[0148] 265: concave part;

[0149] 266: left side wall;

[0150] 268: right side wall;

[0151] 272: lower left part;

[0152] 273: front end components;

[0153] 274: Bottom wall;

[0154] 275: concave part;

[0155] 276: left side wall;

[0156] 278: right side wall;

[0157] 280: right collision energy absorption box;

[0158] 281: fixed parts;

[0159] 282: upper right part;

[0160] 284: upper wall;

[0161] 285: concave part;

[0162] 286: right side wall;

[0163] 288: left side wall;

[0164] 292: lower right part;

[0165] 293: front end components;

[0166] 294: Bottom wall;

[0167] 295: concave part;

[0168] 296: right side wall;

[0169] 298: left side wall;

[0170] A1: first body mounting part;

[0171] A2: Second body mounting part;

[0172] A3: The third body mounting part;

[0173] A4: Fourth body mounting part;

[0174] A5: Fifth body mounting part;

[0175] A6: Sixth body mounting part;

[0176] A7: Steering gearbox left mounting part;

[0177] A8: Steering gearbox right mounting part;

[0178] A9: Mounting part installation;

[0179] A10: Stabilizer left mounting part;

[0180] A11: Stabilizer right mounting part;

[0181] S1: first supporting portion;

[0182] S2: second supporting portion;

[0183] S3: third supporting portion;

[0184] S4: fourth supporting portion;

[0185] J1: left connection;

[0186] J2: right connection;

[0187] E1: left enlargement;

[0188] E2: right enlargement. DETAILED DESCRIPTION

[0189] Below, refer to Figure 1 7, the vehicle subframe in the embodiment of the present invention is described in detail. In the figure, the x-axis, y-axis and z-axis constitute a three-axis orthogonal coordinate system. In addition, the positive direction of the x-axis is the right direction of the vehicle body, the positive direction of the y-axis is the front direction of the vehicle body, and the positive direction of the z-axis is the upper direction of the vehicle body. In addition, the direction of the x-axis is sometimes referred to as the width direction or the lateral direction, the direction of the y-axis is referred to as the front-rear direction, and the direction of the z-axis is referred to as the up-down direction.

[0190] Figures 1 to 3 The diagrams are respectively a top view, a bottom view, and a left side view showing the structure of the vehicle subframe according to the present embodiment. Figure 4A and Figure 4B yes Figure 1 The AA sectional view and the BB sectional view are both longitudinal sectional views cut by a plane parallel to the yz plane formed by the y-axis and the z-axis. Figure 5A , Figure 5B as well as Figure 5C yes Figure 3 The CC sectional view, FF sectional view and GG sectional view are all longitudinal sectional views cut along a plane parallel to the xz plane formed by the x-axis and the z-axis. Fig. 6A 1 is a left partial enlarged side view showing the structure of a crash box of a vehicle subframe according to the present embodiment, Figure 6B 1 is a left partial enlarged side view showing the structure of the side beam of the vehicle subframe of the present embodiment, and the position is equivalent to Figure 3 .in addition, Fig. 7A The vehicle subframe in this embodiment is deformed by a collision load (impact force) applied from the front side to the rear side during a frontal collision of the vehicle. Figure 3 A rather schematic left side view, Figure 7B This is a schematic diagram showing the change in the load (vertical axis) applied to the vehicle subframe relative to the deformation amount (horizontal axis) of the vehicle subframe in the front-to-back direction when the vehicle subframe in this embodiment is deformed by a collision load applied from the front side to the rear side during a frontal collision of the vehicle. Figure 7BIf the deformation is easy to increase during deformation (large time change), the load inclination becomes smaller, and if the deformation is difficult to increase before and after deformation (small time change), the load inclination becomes larger. Fig. 8A is a partial top view of a vehicle subframe in this embodiment, Figure 8B FIG. 1 is a partial bottom view of a vehicle subframe in this embodiment. Figure 3 , Figure 4B , FIG. 5A to FIG. 5C , Fig. 6A , Figure 6B as well as Fig. 7A In the figure, for convenience, one of the reference numerals of the components on the left and the reference numerals of the components on the right is indicated by parentheses. Figure 3 and Fig. 7A In the figure, for convenience, a part of the vehicle body is represented by an imaginary line B. Figure 5A In the diagram, the imaginary line C is used to schematically show Figure 3 The outlines of the DD and EE section views. FIG. 5A to FIG. 5C The cross section in is typically a rectangular cross section, and the dimensions of h1, H1, etc. are expressed as the dimensions between the plates for convenience.

[0191] like Figure 1 As shown in FIG. 7 , the subframe 1 is mounted on a vehicle body such as a front side frame extending in the front-rear direction in a housing chamber that houses one or both of an internal combustion engine and an electric motor as a driving source of a vehicle such as an automobile, and a transmission and a speed reducer required therefor, and supports the driving source, the transmission and speed reducer, the necessary components, the suspension arm, etc. (all omitted from the illustration). The subframe 1 typically has a shape that is bilaterally symmetrical (plane symmetrical) about a plane that is parallel to the yz plane and passes through a center line extending in the front-rear direction at the center of the width direction of the vehicle body.

[0192] In the subframe 1, six locations are set as the parts to be installed on the vehicle body, namely, a first vehicle body mounting portion A1, a second vehicle body mounting portion A2, a third vehicle body mounting portion A3, a fourth vehicle body mounting portion A4, a fifth vehicle body mounting portion A5 and a sixth vehicle body mounting portion A6, and four locations are set as the parts to support the suspension arm, namely, a first supporting portion S1, a second supporting portion S2, a third supporting portion S3 and a fourth supporting portion S4, all of which will be described in detail later.

[0193] In addition, in the subframe 1, mounting portions for mounting various external force applying components are set. As the above-mentioned various mounting portions, there can be listed a steering gear box left mounting portion A7, a steering gear box right mounting portion A8, a plurality of mounting parts mounting portions A9 for mounting required components of a drive source, a transmission and a reducer, a stabilizer left mounting portion A10 and a stabilizer right mounting portion A11, all of which are described in detail later.

[0194] Specifically, the subframe 1 mainly includes: a cross beam 10, which continuously forms a closed cross section in the width direction and is arranged to extend in the width direction; a left mounting member 60, which is connected to the cross beam 10 and the like and is arranged on the left end side thereof; a right mounting member 80, which is connected to the cross beam 10 and the like and is arranged on the right end side thereof; a left side beam 110 and a right side beam 150 as a pair of side beams, which are connected to the cross beam 10, the left mounting member 60, the right mounting member 80 and the like and extend in the front-rear direction and are arranged opposite to each other in the width direction; a rear upper beam 210, which is connected to the cross beam 10, the left mounting member 60, the right mounting member 80, the left side beam 110, the right side beam 150 and the like and is arranged on the rear side of the cross beam 10; a rear lower The beam 230 is connected to the cross beam 10, the left mounting member 60, the right mounting member 80, the left side beam 110, the right side beam 150 and the rear upper beam 210, and is disposed on the lower side of the rear upper beam 210 in the vertical direction and opposite to the rear upper beam 210; the front cross beam 240 extends in the width direction, is disposed on the front side of the cross beam 10 in the front-rear direction, and connects the left side beam 110 and the right side beam 150; the left crash box 260 is connected to the front end of the left side beam 110 and is disposed extending forward from the front end of the left side beam 110; and the right crash box 280 is connected to the front end of the right side beam 150 and is disposed extending forward from the front end of the right side beam 150. These components are typically formed by stamping a flat plate member such as a steel plate, and are integrated by welding by plug welding, arc welding, etc. in a state where the overlapping portions and the butted portions are correspondingly abutted, so that the subframe 1 has a substantially closed cross-sectional shape. In addition, these components may be components obtained by casting metal materials such as aluminum casting materials. In addition, the rear upper beam 210, the rear lower beam 230, the left crash box 260, and the right crash box 280 may be appropriately and selectively omitted when they are not necessary in terms of component layout, strength including during a collision, etc. However, in this embodiment, a structure including these components is used as an example for explanation.

[0195] The cross beam 10 includes: a transverse upper member 12 extending in the width direction; and a transverse lower member 22 disposed on the lower side of the transverse upper member 12, facing the transverse upper member 12 in the vertical direction and extending in the width direction, and abutting against the transverse upper member 12 and typically integrated by arc welding or the like. In addition, the cross beam 10 continuously forms a closed cross section (longitudinal closed cross section) in a plane parallel to the yz plane in the width direction by the transverse upper member 12 and the transverse lower member 22 integrated with each other.

[0196] Specifically, the lateral upper member 12 is typically formed of a single plate member such as a steel plate, is a plate member having a shape that is basically convex in the upward direction, and has an upper wall portion 14, a front longitudinal wall portion 16, and a rear longitudinal wall portion 18 that is opposite to the front longitudinal wall portion 16 in the front-rear direction on the rear side of the front longitudinal wall portion 16. The upper wall portion 14 is provided over the entire length of the lateral upper member 12 in the width direction, but the front longitudinal wall portion 16 and the rear longitudinal wall portion 18 may have a portion where a part of the lateral upper member 12 in the width direction disappears.

[0197] The upper wall 14 connects the front vertical wall 16 and the rear vertical wall 18 and has an extension 20 extending forward in the middle of the width direction. A through hole 21 penetrating the upper wall 14 is formed in the width direction portion of the upper wall 14 corresponding to the extension 20.

[0198] The lateral lower member 22 is typically formed of a single plate member such as a steel plate, and is a plate member that is substantially convex in a downward direction, and includes a bottom wall portion 24, a front vertical wall portion 26, and a rear vertical wall portion 28 that is opposed to the front vertical wall portion 26 in the front-rear direction on the rear side of the front vertical wall portion 26. The bottom wall portion 24, the front vertical wall portion 26, and the rear vertical wall portion 28 are provided over the entire length of the lateral lower member 22 in the width direction, but the front vertical wall portion 26 and the rear vertical wall portion 28 may have a portion where a part of the lateral lower member 22 in the width direction disappears.

[0199] The bottom wall portion 24 has an extension portion 30 extending forward in a manner corresponding to the extension portion 20 of the lateral upper member 12 at a middle portion in the width direction thereof. A through hole 31 penetrating the bottom wall portion 24 is formed in the bottom wall portion 24 at a portion in the width direction corresponding to the extension portion 30, corresponding to the through hole 21 of the lateral upper member 12. A cylindrical member made of metal, i.e., a collar member (not shown) is typically fixedly provided inside the horizontal beam 10 in correspondence with these through holes 21 and 31.

[0200] Here, a left opening end 35 for mounting a left suspension component (not shown) is provided at the left end side of the cross beam 10, and a right opening end 45 for mounting a right suspension component (not shown) is provided at the right end side of the cross beam 10. That is, the left opening end 35 and the right opening end 45 are set at both end sides of the cross beam 10 in the width direction.

[0201] At the left end of the cross member 10, the front longitudinal wall portion 16 and the rear longitudinal wall portion 18 of the transverse upper member 12, and the front longitudinal wall portion 26 and the rear longitudinal wall portion 28 of the transverse lower member 22 are substantially eliminated, so that a left open end portion 35 is formed as an open end portion in a rectangular shape when viewed from the left side, which is surrounded by the upper wall portion 14 of the transverse upper member 12, the bottom wall portion 24 of the transverse lower member 22, the longitudinal wall portion 38 of the left support member 36, and the left front member 64 of the left mounting member 60. At the left open end portion 35, the longitudinal wall portion 38 of the left support member 36 and the left front member 64 of the left mounting member 60 are both flat plate portions and face each other in the front-rear direction, and a through hole 41 penetrating the longitudinal wall portion 38 is formed in the longitudinal wall portion 38 on one side facing each other, and a nut 42 is fixedly provided in the through hole 41 in a manner of standing from the longitudinal wall portion 38 toward the front direction. A through hole 43 is formed in a portion of the left front member 64 of the left mounting member 60 that is opposed to the longitudinal wall portion 38 in the front-rear direction, and passes through the portion, corresponding to the through hole 41 of the longitudinal wall portion 38. The left support member 36 is typically formed of a single plate member such as a steel plate, and has the longitudinal wall portion 38 and a flange portion 40 that is bent from the longitudinal wall portion 38 at least on the upper and lower sides, and the flange portion 40 overlaps and abuts on the lower side of the upper wall portion 14 of the lateral upper member 12 and the upper side of the bottom wall portion 24 of the lateral lower member 22 in the cross member 10, and is typically integrated by welding corresponding to them by arc welding or the like.

[0202] The structure associated with the right open end portion 45 formed at the right end portion of the cross beam 10 is left-right symmetrical with respect to the structure associated with the left open end portion 35 about a plane that is parallel to the yz plane and passes through a center line extending in the front-rear direction at the center in the width direction of the vehicle body, so its detailed description is omitted, but the right open end portion 45 is surrounded by the upper wall portion 14 of the upper transverse member 12, the bottom wall portion 24 of the lower transverse member 22, the vertical wall portion 48 of the right support member 46 and the right front member 84 of the right mounting member 80, and has a through hole 51, a nut 52 and a through hole 53 corresponding to the through hole 41, the nut 42 and the through hole 43 in the left open end portion 35, and is an open end portion that is rectangular when viewed from the right side. The right support member 46 is typically a member formed from a single plate member such as a steel plate, and has a longitudinal wall portion 48 and a flange portion 50 bent from the longitudinal wall portion 48 at least on the upper side and the lower side. The flange portion 50 overlaps and abuts against the lower side of the upper wall portion 14 of the transverse upper member 12 and the upper side of the bottom wall portion 24 of the transverse lower member 22 in the cross beam 10, and is typically integrated by corresponding welding thereof by arc welding or the like.

[0203] A pair of mounting members, namely, a left mounting member 60 and a right mounting member 80 for mounting the subframe 1 to the vehicle body, are disposed on both left and right end sides of the cross member 10 in the width direction so as to correspond to the left opening end 35 and the right opening end 45 .

[0204] The left mounting member 60 includes: a left rear member 62 that protrudes substantially upward and is disposed on the left end side of the cross beam 10; and a left front member 64 that protrudes substantially upward and is disposed on the left end side of the cross beam 10, and is disposed on the front side relative to the left rear member 62. The left rear member 62 and the left front member 64 are each typically a member obtained by stamping a flat plate member such as a steel plate, and they are welded to each other by arc welding or the like, and are integrated in a manner of closing the mutually opened portions, so that the left mounting member 60 has a closed cross-sectional shape. In addition, although the formability becomes complicated, the left rear member 62 and the left front member 64 may be formed from a single plate member such as a steel plate instead of two separate plate members such as steel plates, as required.

[0205] Specifically, the left front member 64 includes a bottom wall portion 65, a front vertical wall portion 66, a left vertical wall portion 67, an inclined wall portion 68, and an upper wall portion 69 as respective wall portions on the lower side, the front side, the left side, the right side, and the upper side thereof. The bottom wall portion 65 is in contact with the upper side of the bottom wall portion 24 of the lateral lower member 22 of the cross member 10 and is welded thereto by plug welding, arc welding, or the like. The front longitudinal wall portion 66 is connected to the bottom wall portion 65, the left longitudinal wall portion 67, the inclined wall portion 68, and the upper wall portion 69. The lower portion of the front longitudinal wall portion 66 is formed as a flat plate portion that is opposed to the flat plate portion having the through hole 41 formed in the longitudinal wall portion 38 of the left support member 36 in the front-rear direction and has the through hole 43. The portion of the front longitudinal wall portion 66 that is above the through hole 43 abuts against the upper wall portion 14 of the upper lateral member 12 of the cross beam 10 and the left upper member 112 of the left side beam 110, respectively, and is welded by arc welding or the like. The left longitudinal wall portion 67 is connected to the bottom wall portion 65, the front longitudinal wall portion 66, and the upper wall portion 69. The inclined wall portion 68 is connected to the front longitudinal wall portion 66 and the upper wall portion 69, and its lower portion abuts against the upper wall portion 14 of the lateral upper member 12 of the cross member 10, the left side member 110 (at least one of the left upper member 112 and the left lower member 132), and the left front end portion of the rear upper member 210, and is welded by arc welding or the like. A through hole 70 is formed in the upper wall portion 69 for inserting a vehicle body mounting bolt (not shown). That is, the left front member 64 is integrated with the cross member 10, the left side member 110, and the rear upper member 210. Furthermore, when the subframe 1 is deformed by a collision load applied from the front side to the rear side during a head-on collision of the vehicle, in order to allow the left mounting member 60 to shift downward, a force is applied from a bolt inserted through the through hole 70 and in a tightened state to the upper wall portion 69 around the through hole 70 to deform it, and in order to allow the bolt to be disengaged from the through hole 70, the hole shape of the through hole 70 may be set to a shape other than a circle, such as an ellipse, a square, or a droplet shape, or a cutout shape may be formed in the peripheral wall of the through hole 70.

[0206] The left rear member 62 includes a wall portion 63 that abuts against each wall portion of the left front member 64 on the rear side of the left front member 64 and is respectively welded by arc welding or the like. In the wall portion 63, further, the lower end portion of the wall portion 63 abuts against the overlapping portion of the bottom wall portion 24 of the lateral lower member 22 of the cross member 10 on the upper side and is welded by arc welding or the like, and the portion that abuts against the left upper member 112 of the left side member 110 and the left front end portion of the rear upper member 210 at a position higher than the lower end portion thereof is respectively welded by arc welding or the like, and the left rear member 62 is integrated with the cross member 10, the left side member 110, and the rear upper member 210.

[0207] The structure associated with the right mounting component 80 arranged on the right end side of the cross beam 10 is symmetrical with respect to the structure associated with the left mounting component 60 about a plane parallel to the yz plane and passing through a center line extending in the front-to-rear direction at the center of the width direction of the vehicle body, so its detailed description is omitted. The right mounting component 80 has a right rear component 82, a wall portion 83, a right front component 84, a bottom wall portion 85, a front longitudinal wall portion 86, a right longitudinal wall portion 87, an inclined wall portion 88, an upper wall portion 89 and a through hole 90 corresponding to the left rear component 62, the wall portion 63, the left front component 64, the bottom wall portion 65, the front longitudinal wall portion 66, the left longitudinal wall portion 67, the inclined wall portion 68, the upper wall portion 69 and the through hole 70 in the left mounting component 60.

[0208] The left side beam 110 includes: a left upper member 112 as a plate member, which is substantially in a convex shape protruding upward, abuts against the upper wall portion 14 of the lateral upper member 12 of the lateral beam 10 on the lower side, and extends in the front-rear direction on the left side; and a left lower member 132 as a plate member, which is arranged to face the left upper member 112 in the upper-lower direction, substantially in a convex shape protruding downward, abuts against the bottom wall portion 34 of the lateral lower member 22 of the lateral beam 10 on the upper side, and extends in the front-rear direction. The left upper member 112 and the left lower member 132 are integrated by correspondingly welding, typically by arc welding, in a state where the overlapping portions and the butted portions are correspondingly abutted. In the left side member 110 , although the formability becomes complicated, the left upper member 112 and the left lower member 132 may be formed from a single plate member such as a steel plate or a tubular member instead of two separate plate members such as steel plates, as required.

[0209] Specifically, the upper left member 112 includes an upper wall portion 114, a left side wall portion 116, and a right side wall portion 118 that is opposite to the left side wall portion 116 in the width direction on the right side of the left side wall portion 116. The upper wall portion 114 connects the left side wall portion 116 and the right side wall portion 118, and has a through hole 119 at its front end portion and a through hole 120 at its rear end portion. The upper left member 112 includes an upper left deflecting portion 121 and an inclined portion 122 between the front end portion and the rear end portion. The left upper deflection portion 121 is a middle portion extending in the front-rear direction from the rear end portion having the through hole 120 toward the front end portion having the through hole 119 in the left upper member 112, where the left side wall portion 116 and the right side wall portion 118 and the upper wall portion 114 accompanying them are deflected to the left relative to the front-rear direction, and particularly, the left side wall portion 116 and the upper wall portion 114 accompanying them have a left upper deflection increasing portion 121a in which the degree of deflection to the left side is increased (when the left side wall portion 116 is a curved surface, the curvature R thereof is reduced, and when the left side wall portion 116 is a folded surface, the folding angle thereof relative to the front-rear direction is increased) at a position closer to the front side than the third vehicle body mounting portion A3 set on the left mounting member 60. However, in the right side wall portion 118, even in the left upper deflection increasing portion 121a, the degree of deflection to the left side is not increased compared with the left side wall portion 116. When viewed from the side, the inclined portion 122 is an intermediate portion between the front end portion and the rear end portion of the upper left member 112, the front end portion having the through hole 119 and extending in the front-back direction without being inclined, and the rear end portion having the through hole 120 and extending in the front-back direction without being inclined. That is, the inclined portion 122 is an intermediate portion of the upper wall portion 114 that descends in the rear direction and extends in a straight line in a manner that begins to descend at the front curved portion 123 and ends to descend at the rear curved portion 124, and the inclination angle α of the inclined portion 122 relative to the front-back direction is typically set to a constant value of 15° or less and greater than 0°. The upper left member 112 has a recessed portion 126 that spans the rear curved portion 124 and a predetermined portion on the front side of the rear curved portion 124 in the inclined portion 122, and is recessed in a manner that the general portion G of the upper wall portion 114 protrudes toward the lower left member 132 in a direction A' perpendicular to the extending direction (inclined direction) A in which the inclined portion 122 extends at the inclination angle α.The recessed portion 126 is set to extend along the inclined direction A at the rear end of the inclined portion 122 by a predetermined length. The position of the end of the recessed portion 126 on the rear curved portion 124 side, i.e., the rear end, is set so that the distance from the rear end to the rear curved portion 124 is shorter than the distance from the rear end to the front curved portion 123. Typically, it is set to coincide with the position of the rear curved portion 124 (the position of the folding line when the rear curved portion 124 is a curved portion, and the position within the curved range when the rear curved portion 124 is a curved portion). However, the changing surface between the general portion G of the upper wall portion 114, which is not recessed, and the recessed portion 126 may extend to the rear end side of the left upper member 112 beyond the rear curved portion 124. In addition, when the recessed portions 126 and 146, which will be described in detail later, are crushed in the front-rear direction, the inclination angle α is preferably set to a constant value of 10° or less from the viewpoint of stably causing the crushing.

[0210] The left lower member 132 includes a bottom wall portion 134, a left side wall portion 136, and a right side wall portion 138 that is opposite to the left side wall portion 136 in the width direction on the right side of the left side wall portion 136. The bottom wall portion 134 connects the left side wall portion 136 and the right side wall portion 138, and has a through hole 139 at its front end portion and a through hole 140 at its rear end portion. The left lower member 132 includes a left lower deflection portion 141 and an inclined portion 142 between the front end portion and the rear end portion. When viewed from above, the lower left deflection portion 141 is, in the lower left component 132, an intermediate portion extending in the front-to-rear direction from the rear end portion having the through hole 140 toward the front end portion having the through hole 139, wherein the left side wall portion 136, the right side wall portion 138 and the bottom wall portion 134 accompanying them are deflected to the left relative to the front-to-rear direction, particularly at a position closer to the front side than the third vehicle body mounting portion A3 set on the left mounting component 60. Similar to the left side wall portion 116, the right side wall portion 118 and the upper wall portion 114 accompanying them of the upper left component 112, the left side wall portion 136 and the bottom wall portion 134 accompanying them have a lower left deflection increasing portion 141a in which the degree of deflection to the left is increased (when the left side wall portion 136 is a curved surface, its curvature R becomes smaller, and when the left side wall portion 136 is a folded surface, its folding angle relative to the front-to-rear direction becomes larger). However, in the right side wall portion 138, even in the lower left deflection increasing portion 141a, the degree of lateral deflection in the left direction is not increased compared to the left side wall portion 136. When viewed from the side, the inclined portion 142 is an intermediate portion between the front end portion and the rear end portion of the lower left member 132, the front end portion having the through hole 139 and extending in the front-to-back direction without being tilted, and the rear end portion having the through hole 140 and extending in the front-to-back direction without being tilted. That is, the inclined portion 142 is an intermediate portion that descends in the rear direction parallel to the inclined direction A at an inclined angle α in the bottom wall portion 134 in a manner that starts descending at the front curved portion 143 and ends descending at the rear curved portion 144 and extends in a straight line. However, the inclined portion 142 may also include a steeply inclined portion 145 that is continuously connected to the front curved portion 143 in the rear direction and descends at an inclined angle greater than the inclined angle α. The left lower member 132 has a recessed portion 146 which is arranged across the rear curved portion 144 and a predetermined portion on the front side of the rear curved portion 144 in the inclined portion 142 and is recessed in the direction A' so that the general portion G of the bottom wall portion 134 protrudes toward the left upper member 112. The recessed portion 146 is opposed to the recessed portion 126 of the left upper member 112 in the direction A', that is, the portion of the recessed portion 146 where the bottom wall portion 134 is recessed and the portion of the recessed portion 126 of the left upper member 112 where the upper wall portion 114 is recessed are typically in a positional relationship parallel to each other and overlap in a manner that they have the same contour shape when viewed in the direction A' and do not protrude. The bottom wall portion 134 has through holes 147, 148, and 149 between the rear curved portion 144 and the through hole 140 in the front-rear direction.The through holes 139 and 140 are arranged on the lower side of the through holes 119 and 120 of the upper left component 112 so as to be vertically opposed to them, and a through hole (not shown) is formed on the upper side of the through holes 147, 148 and 149 so as to be vertically opposed to them, and a through hole (not shown) is formed in the upper left component 112, and a cylindrical shaft ring component (not shown) which is typically made of metal is fixedly provided inside the left side beam 110 corresponding to these through holes.

[0211] In the left side member 110, when the subframe 1 is deformed by a collision load applied from the front side to the rear side during a frontal collision of the vehicle, the front curved portions 123 and 143, the rear curved portions 124 and 144, and the recessed portions 126 and 146 function as fragile portions. Specifically, by the application of the collision load, the recessed portions 126 and 146 begin to be crushed in the front-to-back direction. When they are crushed in the front-to-back direction to a length of, for example, 20% to 30% of the initial full length of the recessed portions 126 and 146 in the front-to-back direction, the front curved portions 123 and 143, the rear curved portions 124 and 144, and the recessed portions 126 and 146 function as fragile portions. If the length of the upper left part 112 and the lower left part 132 is shortened to less than 30%, it becomes substantially completely crushed, and the front curved parts 123 and 143 begin to bend and deform convexly upward, and the rear curved parts 124 and 144 begin to bend and deform convexly downward with the concave parts 126 and 146 that are compressed and shortened as the starting point of the bending. When the collision load is applied, the two sides formed by the bending of the front curved parts 123 and 143 and the rear curved parts 124 and 144 are close to each other. Here, typically, the material and plate thickness of the upper left part 112 and the lower left part 132 are set to the same material and plate thickness. If the comparison is made, Figure 5B The cross-sectional area of ​​the longitudinal section of the front curved portion 123 and 143 shown, Figure 5C The cross-sectional area of ​​the longitudinal section of the rear curved portions 124 and 144 indicated by the imaginary line G in FIG. Figure 5CAs shown in the cross-sectional area of ​​the longitudinal section of the recesses 126 and 146 , the cross-sectional area of ​​the recesses 126 and 146 is set to be the smallest, and the recesses 126 and 146 extend by a predetermined length in the inclined direction A, so the depression of the recesses 126 and 146 starts first. Next, regarding the front curved portions 123 and 143 and the rear curved portions 124 and 144 arranged in sequence in the front-to-back direction via the inclined portions 122 and 142, in the longitudinal section of the front curved portions 123 and 143, the width (length in the width direction) b1 is much wider than the width b2 in the longitudinal section of the rear curved portions 124 and 144, but in order to make the bending strength of the front curved portions 123 and 143 equal to that of the rear curved portions 124 and 144, the height (length in the up-down direction) h1 is set to be lower than the height h2 in the longitudinal section of the rear curved portions 124 and 144 by a specified length, so that the bending deformation of the front curved portions 123 and 143 convex to the upward side and the bending deformation of the rear curved portions 124 and 144 convex to the downward side start substantially at the same time. At this time, the portion that becomes the starting point of the bending so that the rear curved portions 124 and 144 bulge downward is the concave portions 126 and 146 that are compressed to a predetermined length and shortened in the longitudinal section lower in height than the longitudinal section of the rear curved portions 124 and 144 and are located in front of the rear curved portions 124 and 144 adjacent to the rear curved portions 124 and 144. In addition, when the inclined portion 142 and the front curved portion 143 continuously include the steeply inclined portion 145, the bending deformation of the front curved portions 123 and 143 bulging upward is further promoted. In addition, the material and plate thickness of the upper left member 112 and the lower left member 132 may be different as needed.

[0212] In addition to being welded to the left mounting member 60, the left side beam 110 is integrated with the cross beam 10 by welding the left upper member 112 to the front longitudinal wall portion 16 of the cross upper member 22 of the cross beam 10 from the front direction side, typically by arc welding, and by abutting the left lower member 132 on the upper direction side of the bottom wall portion 24 of the cross lower member 22 of the cross beam 10 and welding it by plug welding, arc welding, etc. In addition, the left side beam 110 is integrated with the rear upper beam 210 and the rear lower beam 230 by abutting the left upper member 112 against the left rear end portion of the rear upper beam 210 and welding it by arc welding, etc., and by abutting the left lower member 132 against the left end portion of the rear lower beam 230 and welding it by arc welding, etc. In addition, the left upper member 112 and the left lower member 132 are composed of a single plate member such as a steel plate, but can also be composed by connecting a plurality of plate members such as steel plates divided in the middle of the front-rear direction as needed. Furthermore, the plurality of plate members may have different plate thicknesses.

[0213] The structure of the right side beam 150 disposed on the right side of the left side beam 110 and opposite to the left side beam 110 in the width direction is symmetrical with respect to the structure of the left side beam 110 about a plane parallel to the yz plane and passing through a center line extending in the front-rear direction at the center of the width direction of the vehicle body, so its detailed description is omitted, but the left upper member 112, the upper wall portion 114, the left side wall portion 116, the right side wall portion 118, the through holes 119, 120, the left upper deflection portion 121, the left upper deflection increasing portion 121a, the inclined portion 122, the front curved portion 123, the rear curved portion 124, the recessed portion 126, the through holes 127, 128 and 129, the left lower member 132, the bottom wall portion 134, the left side wall portion 136, the right side wall portion 138, the through holes 139, 140, the left lower deflection portion 141, the left lower deflection increasing portion 141a, inclined portion 142, front curved portion 143, rear curved portion 144, steeply inclined portion 145, recess 146, through holes 147, 148 and 149 respectively have a right upper component 152, an upper wall portion 154, a right side wall portion 156, a left side wall portion 158, through holes 159, 160, a right upper deflection portion 161, a right upper deflection increasing portion 161a, an inclined portion 162, a front curved portion 163, a rear curved portion 144, a steeply inclined portion 145, a recess 146, a through hole 147, 148 and 149 respectively have a right upper component 152, an upper wall portion 154, a right side wall portion 156, a left side wall portion 158, a through hole 159, 160, a right upper deflection portion 161, a right upper deflection increasing portion 161a, an inclined portion 162, a front curved portion 163, a rear curved portion The curved portion 164, the recess 166, the through holes 167, 168 and 169, the lower right part 172, the bottom wall portion 174, the right side wall portion 176, the left side wall portion 178, the through holes 179, 180, the lower right deflection portion 181, the lower right deflection increasing portion 181a, the inclined portion 182, the front curved portion 183, the rear curved portion 184, the steeply inclined portion 185, the recess 186, the through holes 187, 188 and 189.

[0214] The rear upper beam 210 is a plate member whose front end middle portion extending in the width direction overlaps with the rear end portion of the upper wall portion 14 of the lateral upper member 12 of the cross beam 10 from the upper side, whose left end portion overlaps with the left rear member 62 and the left front member 64 of the left mounting member 60 from the upper side, whose right end portion overlaps with the right rear member 82 and the right front member 84 of the right mounting member 80 from the upper side, and whose left and right ends extending in the front-rear direction overlap with the upper wall portion 114 of the left upper member 112 of the left side beam 110 and the upper wall portion 154 of the right upper member 152 of the right side beam 150 from the upper side. In this way, the ends of the overlapping portions of the rear upper beam 210 are correspondingly welded by arc welding or the like, whereby the rear upper beam 210 is integrated with the cross beam 10, the left mounting member 60, the right mounting member 80, the left side beam 110, and the right side beam 150. In addition, the rear end portion of the rear upper beam 210 extending in the width direction is typically welded to the rear lower beam 230 by arc welding or the like so as to be integrated therewith.

[0215] Specifically, nuts 211 and 212 that stand upward are fixedly provided at the left and right ends of the front end portion extending in the width direction of the rear upper beam 210, corresponding to the rear direction sides of the left mounting member 60 and the right mounting member 80. The nuts 211 and 212 are used to correspondingly mount one of a plurality of fixing portions of a steering gear box (not shown), and through holes 213 and 214 are formed in the rear upper beam 210 corresponding to the nuts 211 and 212. In the rear upper beam 210, through holes 215, 216, and 217 are formed on the upper side of the through holes 147, 148, and 149 of the left lower member 132 of the left side beam 110, and are opposed to each other in the vertical direction. A groove 218 is formed between the through holes 215 and 216 in the width direction. The groove 218 is formed by recessing a part of the rear upper beam 210 downward, and allows a stabilizer bar (not shown) to be inserted freely in the width direction. Similarly, in the rear upper beam 210, through holes 225, 226, and 227 are formed on the upper side of the through holes 187, 188, and 189 of the right lower member 172 of the right side beam 150, and are opposed to each other in the vertical direction. The groove 218 between the through holes 215 and 216 extends continuously in the width direction.

[0216] The rear lower beam 230, which is vertically opposed to the rear upper beam 210 on the lower side of the rear upper beam 210, is a plate member whose front end portion extending in the width direction overlaps with the rear end portion of the bottom wall portion 24 of the lateral lower member 22 of the cross beam 10 from the lower side in the vertical direction, and whose left and right ends extending in the front-rear direction overlap with the right end portion of the bottom wall portion 134 of the left lower member 132 of the left side beam 110 and the left end portion of the bottom wall portion 174 of the right lower member 172 of the right side beam 150 in the vertical direction, and through holes 233 and 234 are formed on the lower side of the through holes 213 and 214 of the rear upper beam 210 and are vertically opposed to them. In addition, the ends of the overlapping portion of the rear lower beam 230 are correspondingly welded by arc welding or the like, thereby integrating the rear lower beam 230 with the cross beam 10, the left side beam 110, and the right side beam 150. In addition, the rear end portion of the rear lower beam 230 extending in the width direction is in contact with the rear end portion of the rear upper beam 210, and is typically welded by arc welding or the like, thereby integrating the rear lower beam 230 with the rear upper beam 210. In addition, the portion surrounded by the cross beam 10, the left side beam 110, the right side beam 150, the rear upper beam 210, and the rear lower beam 230 forms a closed space.

[0217] The left side of the front cross beam 240 abuts against the left side beam 110 between the front curved portions 123 and 143 and the recessed portions 126 and 146 in the front-rear direction of the left side beam 110, and is typically welded to the left side beam 110 by arc welding or the like to be integrated, and the right side of the front cross beam 240 abuts against the right side beam 150 between the front curved portions 163 and 183 and the recessed portions 166 and 186 in the front-rear direction of the right side beam 150, and is typically welded to the right side beam 150 by arc welding or the like to be integrated. The front cross beam 240 includes: a lateral upper member 242 extending in the width direction; and a lateral lower member 252 disposed on the lower side of the lateral upper member 242 facing the lateral upper member 242 in the vertical direction and extending in the width direction, and abutting against the lateral upper member 242 and typically welded to the lateral upper member 242 by arc welding or the like to be integrated. In addition, the front cross member 240 forms a closed cross section (longitudinal closed cross section) in a plane parallel to the yz plane continuously in the width direction by the mutually integrated upper cross member 242 and lower cross member 252 .

[0218] Specifically, the lateral upper member 242 is typically formed of a single plate member such as a steel plate, and is a plate member that is substantially convex in an upward direction, and includes an upper wall portion 244, a front longitudinal wall portion 246, and a rear longitudinal wall portion 248 that is opposed to the front longitudinal wall portion 246 in the front-rear direction on the rear side of the front longitudinal wall portion 246. The upper wall portion 244 connects the front longitudinal wall portion 246 and the rear longitudinal wall portion 248, and has a plurality of through holes 249. In the lateral upper member 242, the left end portion of the upper wall portion 244 abuts against the upper wall portion 114 of the left upper member 112 of the left side beam 110, and the left ends of the front longitudinal wall portion 246 and the rear longitudinal wall portion 248 abut against the right side wall portion 118 of the left upper member 112 of the left side beam 110, and are typically welded to these by arc welding or the like to form an integrated left connecting portion J1.

[0219] The lateral lower member 252 is typically formed of a single plate member such as a steel plate, and is a plate member that is substantially convex downward, and includes a bottom wall portion 254, a front vertical wall portion 256, and a rear vertical wall portion 258 that is opposed to the front vertical wall portion 256 in the front-rear direction on the rear side of the front vertical wall portion 256. The bottom wall portion 254 connects the front vertical wall portion 256 and the rear vertical wall portion 258, and has a plurality of through holes 259 that are opposed to the through holes 249 of the lateral upper member 242 in the upper and lower directions corresponding to the through holes 249. The lateral lower member 252 has a left end portion of the bottom wall portion 254 abutting against the bottom wall portion 134 of the left lower member 132 of the left side beam 110 in the left lower deflection increasing portion 141a of the left side beam 110, and a left end portion of each of the front longitudinal wall portion 256 and the rear longitudinal wall portion 258 abutting against the right side wall portion 138 of the left lower member 132 of the left side beam 110, and is typically welded to them by arc welding or the like to form an integrated left connecting portion J1 similarly to the lateral upper member 242. Here, from the viewpoint of increasing the contact area of ​​the left connecting portion J1 of the front cross beam 240 with the left side beam 110, it is preferred that the lateral upper member 242 and the lateral lower member 252 of the front cross beam 240 cooperate to have a left enlarged portion E1 in which the width (length) w of the front cross beam 240 increases as the width (length) w of the front cross beam 240 increases from the center portion in the width direction toward the left side. Specifically, the front cross member 240 is formed from the center in the width direction toward the left side, and at least one of the pair of front longitudinal wall portions 246, 256 and the pair of rear longitudinal wall portions 248, 258 is deflected toward the front direction side in the case of the pair of front longitudinal wall portions 246, 256, and toward the rear direction side in the case of the pair of rear longitudinal wall portions 248, 258, and accordingly, the upper wall portion 244 and the bottom wall portion 254 form a left enlarged portion E1 extending toward at least one of the front direction side and the rear direction side. In addition, from the viewpoint of improving the connection strength of the left side member 110, it is preferable that the left connection portion J1 is set closer to the through hole 119 of the left upper member 112 and the through hole 139 of the left lower member 132 of the left side member 110 than to the through hole 70 of the upper wall portion of the left mounting member 60. In addition, in the front cross member 240, although the formability becomes complicated, the upper lateral member 242 and the lower lateral member 252 may be formed of a single plate member such as a steel plate or a tube member instead of two separate plate members such as steel plates, as required. In addition, in the front cross member 240, the connection structure connected to the right side member 150 is bilaterally symmetrical with respect to the connection structure connected to the left side member 110 about a plane parallel to the yz plane and passing through a center line extending in the front-rear direction at the center of the width direction of the vehicle body, so the detailed description thereof is omitted, but the right connection part J2 and the right enlarged part E2 are provided corresponding to the left connection part J1 and the left enlarged part E1.

[0220] The left crash energy absorbing box 260 includes: a fixing member 261, which is typically welded to the rear end of the left crash energy absorbing box 260 by arc welding or the like, and is fastened to the front end of the left side beam 110 by bolts or the like whose reference numerals are omitted; a left upper member 262, which extends in the front-to-rear direction; a left lower member 272, which is disposed on the lower side of the left upper member 262 in the up-down direction opposite to the left upper member 262 and extending in the front-to-rear direction, and is integrated by abutting against the left upper member 262 and being welded to the left upper member 262 by arc welding or the like; and a front end member 273 as a flat plate member, which is typically welded to the front ends of the upper left member 262 and the lower left member 272 by arc welding or the like. The left crash energy absorbing box 260 is a cylindrical member whose front end is blocked by the front end member 273. In addition, in the left crash box 260, although the formability becomes complicated, the upper left member 262 and the lower left member 272 may be formed of a single plate member such as a steel plate or a tube member instead of two separate plate members such as steel plates, as required. In addition, typically, the material and plate thickness of the upper left member 262 and the lower left member 272 are set to the same material and plate thickness. In addition, the material and plate thickness of each of them may be different as required.

[0221] In detail, the upper left member 262 is typically formed of a single plate member such as a steel plate, and is a plate member that is basically shaped to protrude upward, and includes an upper wall portion 264, a left side wall portion 266, and a right side wall portion 268 that is opposite to the left side wall portion 266 in the width direction on the right side of the left side wall portion 266. The upper wall portion 264 connects the left side wall portion 266 and the right side wall portion 268, and has a plurality of recesses 265 between its front end portion and its rear end portion in the front-rear direction, and the plurality of recesses 265 are recessed and provided in a manner that protrudes downward at the general portion G indicated by the imaginary line in the upper wall portion 264. The lengths of the plurality of recesses 265 in the front-rear direction are typically set such that the length L1 in the front-rear direction of the recess 265 provided on the most front side is longer than the length Ln in the front-rear direction of the recess 265 provided on the rear side.

[0222] The lower left component 272 is typically formed from a single plate component such as a steel plate, and is a plate component that is basically shaped to protrude downward, and has a bottom wall portion 274, a left side wall portion 276, and a right side wall portion 278 that is opposite to the left side wall portion 276 in the width direction on the right side of the left side wall portion 276. The bottom wall portion 274 connects the left side wall portion 276 and the right side wall portion 278, and in the front-to-back direction, between its front end portion and its rear end portion, has a plurality of recesses 275 that are opposite to the plurality of recesses 265 of the upper left component 262 in the upper and lower directions in correspondence with them. The plurality of recesses 275 are recessed in the general portion G indicated by the imaginary line in the bottom wall portion 274 in a manner that protrudes upward. The lengths of the plurality of recesses 275 in the front-to-back direction are similar to the lengths of the plurality of recesses 265 of the upper left member 262, and are typically set such that the length L1 of the recess 275 disposed on the most forward direction side is longer than the length Ln of the recess 275 disposed on the rearward direction side thereof. The plurality of recesses 265 and 275 function as fragile portions, and the length L1 of the recesses 265 and 275 disposed on the most forward direction side is set to be longer than the length Ln of the recesses 265 and 275 disposed on their rearward direction sides. Therefore, the plurality of recesses 265 and 275 begin to collapse in the front-to-back direction starting from the recesses 265 and 275 disposed on the most forward direction side. In addition, as Figure 5A As shown, by setting the height H1 of the recesses 265 and 275 disposed on the frontmost direction side to be lower than the height Hn of the recesses 265 and 275 disposed on their rearward direction sides (indicated by the imaginary line C), the multiple recesses 265 and 275 can more reliably begin to collapse in the front-to-back direction with the recesses 265 and 275 disposed on the frontmost direction side as the starting point.

[0223] Typically, the material and thickness of the left upper member 262 and the left lower member 272 of the left crash box 260 are set to be the same as the material and thickness of the left upper member 112 and the left lower member 132 of the left side beam 110, or to be weaker and thinner than them. Figure 5A The cross-sectional area of ​​the longitudinal section of the plurality of recesses 265 and 275 shown is set to be greater than Figure 5B The cross-sectional area of ​​the longitudinal section in the front curved portion 123 and 143 shown, Figure 5C The cross-sectional area of ​​the longitudinal section of the rear curved portions 124 and 144 indicated by the imaginary line G, and Figure 5C The cross-sectional area of ​​the longitudinal section of the recessed portions 126 and 146 shown is small. Therefore, when the subframe 1 is deformed by a collision load applied from the front side to the rear side during a frontal collision of the vehicle, the recessed portions 126 and 146 begin to collapse first.

[0224] The structure of the right crash box 280 disposed on the right side of the left crash box 260 and opposite to the left crash box 260 in the width direction is symmetrical with respect to the structure of the left crash box 260 about a plane parallel to the yz plane and passing through a center line extending in the front-rear direction at the center of the width direction of the vehicle body, so the detailed description thereof is omitted. However, the fixing member 261, the left upper member 262, the upper wall portion 264, and the recessed portion 266 of the left crash box 260 are 5. The left side wall portion 266, the right side wall portion 268, the lower left component 272, the front end component 273, the bottom wall portion 274, the recess 275, the left side wall portion 276 and the right side wall portion 278 correspondingly have a fixing component 281, an upper right component 282, an upper wall portion 284, a recess 285, the right side wall portion 286, the left side wall portion 288, the lower right component 292, the front end component 293, the bottom wall portion 294, the recess 295, the right side wall portion 296 and the left side wall portion 298.

[0225] In addition, for the subframe 1 having the above structure, when a collision load from the front side to the rear side is applied to the subframe 1 during a frontal collision of the vehicle, a deformation mode of the subframe 1 is described in detail. Here, the deformation mode of the subframe 1 is that among the components on the left side, the left crash box 260 and the left side beam 110 are deformed in this order, and the left side beam 110 is bent and deformed after the crushing is completed, and among the components on the right side, the right crash box 280 and the right side beam 150 are deformed in this order, and the right side beam 150 starts to bend and deform after the crushing is completed. In order to realize this deformation mode, a structure that reflects the mechanical characteristics that define these deformation characteristics, such as the material, plate thickness, cross-sectional shape, and cross-sectional area of ​​these components is set in advance, and the mechanical characteristics of the components on the left side of the subframe 1 and the mechanical characteristics of the components on the right side of the subframe 1 are mutually symmetrical structures, and are set to be the same mechanical characteristics. In addition, it is typically assumed that the collision load is applied rapidly and with equal magnitude to two locations at the front end portions (front end members 273 and 293) of the left crash box 260 and the right crash box 280, and therefore, the following description will be mainly focused on the components on the left side of the subframe 1.

[0226] First, when the collision load is applied, in the early deformation mode, when the left crash box 260 disposed at the frontmost side among the components on the left side of the subframe 1 is slightly elastically deformed in the front-to-rear direction and the deformation amount becomes D1, that is, the front end member 273 of the left crash box 260 is displaced from the initial position before the collision load is applied to the rear side in the front-to-rear direction to the length D1 and the displacement amount becomes D1, the subframe 1, that is, the left crash box 260 receives the load F1 transmitted toward the rear side, and the left upper member 262 of the left crash box 260 is deformed slightly elastically in the front-to-rear direction and the deformation amount becomes D1. The recessed parts 265 and 275 of the left lower member 272 disposed on the most forward side begin to be crushed in the front-to-back direction toward the rear side. When the displacement of the front end member 273 reaches D3 (> D1), the recessed parts 265 and 275 on the rear side thereof are completely crushed. When the recessed parts 265 and 275 are crushed to a length of, for example, less than 20% to 30% of the initial total length of the left crash box 260 in the front-to-back direction and shortened, the recessed parts 265 and 275 are substantially completely crushed. The crushing ends here, and the left side beam 110 receives the load F3 (> F1) transmitted toward the rear side. Thus, in the early deformation mode until the displacement of the front end member 273 changes from zero to D3, the load transmitted to the left crash box 260 changes from zero to F3, and the crushing ends after the recessed parts 265 and 275 start, and the deformation of the left crash box 260 in the front-to-back direction reaches D3. In addition, the displacement of the front end component 273 is D2 (D3>D2>D1), and the load borne by the subframe 1 is temporarily increased to F2 (F3>F2>F1). The maximum value of the load borne by the subframe 1 is obtained during the period from the beginning to the end of the crushing of the recesses 265 and 275. A part of the load is considered to be borne by the left side beam 110 without deformation, but this load F2 can be considered to be the maximum value of the load borne by the recesses 265 and 275 in practical terms.

[0227] Next, during the application of the collision load, in the mid-term deformation mode, the load F3 transmitted to the left side beam 110 causes the left side beam 110 to undergo transitional elastic deformation, and the displacement of the front end component 273 of the left crash box 260 in the front-to-rear direction reaches D4 (>D3). The recesses 126 and 146 of the left side beam 110 receive the load F4 (>F3) at this time, and the recesses 126 and 146 begin to be crushed in the inclined direction A. At the subsequent displacement D5 (>D4), the maximum value F5 (>F4) of the load borne by the subframe 1 during the period from the beginning to the end of the crushing of the recesses 126 and 146 is obtained. When the displacement of the front end member 273 reaches D6 (> D5), the recesses 126 and 146 are substantially completely crushed and the crushing is substantially terminated, and the front curved portions 123 and 143 and the rear curved portions 124 and 144 of the left side beam 110 receive the load F6 (> F5) at this time.

[0228] Next, during the application of the collision load, in the late deformation mode, the load F6 borne by the front curved portions 123 and 143 and the rear curved portions 124 and 144 of the left side beam 110 causes the front curved portions 123 and 143 to begin to bend and deform convexly toward the upward direction, and with the recessed portions 126 and 146 where the crushing is substantially completed as the starting point of the bending, the rear curved portions 124 and 144 begin to bend and deform convexly toward the downward direction, thereby presenting a bending state in which the two sides formed by the bending of the front curved portions 123 and 143 and the rear curved portions 124 and 144 are respectively close to each other. Accompanied by this, the bolts fastened to the vehicle body B through the through hole 70 of the upper wall portion 69 of the left mounting component 60 deform the through hole 70 and detach from the through hole 70, and the third vehicle body mounting portion A3 in the left center falls off from the vehicle body B, and the left mounting component 60 moves downward together with the left side beam 110 in the bending deformation. Then, thereafter, the two sides formed by bending the front curved portions 123 and 143 and the rear curved portions 124 and 144 are bent so as to approach each other. Here, in the above-mentioned early deformation mode to the late deformation mode, the front cross beam 240 suppresses the left beam 110 and the right beam 150 from deforming outwards and deviating from each other, thereby suppressing the generation of an unnecessary deformation mode.

[0229] In the above structure, the first vehicle body mounting portion A1 on the left front, which is the various parts of the vehicle body to which the subframe 1 is mounted, corresponds to the through hole 119 provided in the left upper member 112 of the left side beam 110, the through hole 139 provided in the left lower member 132 of the left side beam 110, and the collar member provided corresponding to them and not shown in the figure; the second vehicle body mounting portion A2 on the right front, which corresponds to the through hole 159 provided in the right upper member 152 of the right side beam 150, the through hole 179 provided in the right lower member 172 of the right side beam 150, and the collar member provided corresponding to them and not shown in the figure; the third vehicle body mounting portion A3 on the left middle, which corresponds to the through hole 159 provided in the right upper member 152 of the right side beam 150, the through hole 179 provided in the right lower member 172 of the right side beam 150, and the collar member provided corresponding to them and not shown in the figure; The through hole 70 of the upper wall portion 69, as the fourth vehicle body mounting portion A4 in the middle right, corresponds to the through hole 90 provided in the upper wall portion 89 of the right mounting member 80, and the fifth vehicle body mounting portion A5 in the rear left corresponds to the through hole 120 provided in the left upper member 112 of the left beam 110, the through hole 140 provided in the left lower member 132 of the left beam 110, and the collar member provided corresponding to them and not shown in the figure, and the sixth vehicle body mounting portion A6 in the rear right corresponds to the through hole 160 provided in the right upper member 152 of the right beam 150, the through hole 180 provided in the right lower member 172 of the right beam 150, and the collar member provided corresponding to them and not shown in the figure. In addition, these parts are typically fastening parts using fastening members such as bolts. In addition, as these parts, an example of a rigid structure without a subframe mounting member is assumed.

[0230] In addition, among various parts of the subframe 1 that respectively support the inner pivot part of the suspension arm, the first support part S1 as the left front corresponds to the through hole 41 and the nut 42 provided in the left support member 36, and the left open end part 35 having the through hole 43 provided in the left mounting member 60. The second support part S2 as the right front corresponds to the through hole 51 and the nut 52 provided in the right support member 46, and the right open end part 45 having the through hole 53 provided in the right mounting member 80. The third support part S3 as the left rear corresponds to the through hole 149 provided in the left lower member 132 of the left side beam 110, the through hole 217 provided in the rear upper beam 210, and the collar member provided corresponding to them and not shown in the figure. The fourth support part S4 as the right rear corresponds to the through hole 189 provided in the right lower member 172 of the right side beam 150, the through hole 227 provided in the rear upper beam 210, and the collar member provided corresponding to them and not shown in the figure. In addition, these parts are typically fastened parts using fastening parts such as bolts. In addition, as the suspension arm suitable for these parts, an example of using an L-shaped lower arm is envisioned, but an A-shaped lower arm or two I-shaped lower arms may also be used. In addition, in the left front first support part S1 and the right front second support part S2, an example of fastening the inner tube of the insulating bushing part (not shown) is envisioned, and in the left rear third support part S3 and the right rear fourth support part S4, although the illustration is omitted, an example of fastening the bracket and installing the insulating bushing part on the bracket is envisioned.

[0231] In addition, among the various mounting portions for mounting various external force applying components on the subframe 1, the left mounting portion A7 of the steering gear box corresponds to the nut 211 and the through hole 213 provided on the rear upper beam 210, and the through hole 233 provided on the rear lower beam 230; the right mounting portion A8 of the steering gear box corresponds to the nut 212 and the through hole 214 provided on the rear upper beam 210, and the through hole 234 provided on the rear lower beam 230; and the mounting member mounting portion A9 corresponds to the through hole 21 provided on the upper lateral member 12 of the cross member 10, the through hole 31 provided on the lower lateral member 22, and the through hole 32 provided on the upper lateral member 242 of the front cross member 240. The hole 249, the through hole 259 provided in the lateral lower member 252, and the collar member provided corresponding to them and not shown in the figure, as the left stabilizer mounting portion A10, correspond to the through holes 147 and 148 provided in the left lower member 132 of the left side beam 110, the through holes 215 and 216 provided in the rear upper beam 210, and the collar member provided corresponding to them and not shown in the figure, and as the right stabilizer mounting portion A11, correspond to the through holes 187 and 188 provided in the right lower member 172 of the right side beam 150, the through holes 225 and 226 provided in the rear upper beam 210, and the collar member provided corresponding to them and not shown in the figure. In addition, these parts are typically fastened parts using fastening members such as bolts. In addition, in the steering gear box left mounting part A7 and the steering gear box right mounting part A8, an example of correspondingly fastening the left and right mounting seats of the steering gear box body is envisioned, and in the mounting part mounting part A9, an example of fastening a bracket (not shown) for installing the required components of the drive source, transmission and reducer is envisioned, and in the stabilizer left mounting part A10 and the stabilizer right mounting part A11, although both are omitted from the illustration, an example of fastening the brackets respectively and installing the stabilizer bar on the brackets via the bushing parts is envisioned.

[0232] In the subframe 1 of the present embodiment described above, the first side member 110 has the first extension portions 121, 141 that are deflected and extended toward the outer side of one side in the width direction as it goes from the rear direction side to the front direction side, the second side member 150 has the second extension portions 161, 181 that are deflected and extended toward the outer side of the other side in the width direction as it goes from the rear direction side to the front direction side, and further includes a second cross member 240 that is opposed to the first cross member 10 on the front direction side and deflects the deflected portions 161, 181 that are deflected and extended toward the outer side of one side in the width direction in the first extension portions 121, 141. The portions 121a, 141a with a greater degree of deflection are connected to the portions 161a, 181a with a greater degree of deflection that are deflected toward the outside of the other side in the width direction in the second extension portions 161, 181, so that, in a so-called offset collision, when a frontal collision load that is offset to the left or right side of the vehicle is applied to one of the first side beam 110 and the second side beam 150, unnecessary deformation of the side beam 110, 150 on the one side toward the outside in the width direction can be suppressed, and the collision load can be transmitted to the other side beam 150, 110 and dispersed.

[0233] In addition, in the subframe 1 of the present embodiment, the connection portion J1 of the second cross beam 240 connected to the first side beam 110 has a first enlarged portion E1 whose length in the front-to-rear direction increases as it goes to one side in the width direction, and the connection portion J2 of the second cross beam 240 connected to the second side beam 150 has a second enlarged portion E2 whose length in the front-to-rear direction increases as it goes to the other side in the width direction. As a result, it is possible to reliably suppress unnecessary deformation of the side beams 110, 150 to which the collision load is applied toward the outer sides in the width direction, and it is possible to reliably disperse the collision load.

[0234] In addition, in the subframe 1 of the present embodiment, in the first enlarged portion E1, at least one of the wall portion on the front side and the wall portion on the rear side of the first enlarged portion E1 extends in the front-to-rear direction, and in the second enlarged portion E2, at least one of the wall portions 16, 26 on the front side and the wall portions 18, 28 on the rear side of the second enlarged portion E2 extends in the front-to-rear direction. As a result, the side beams 110, 150 can be reliably connected in accordance with the degree of freedom of layout around the subframe 1, and unnecessary deformation of the side beams 110, 150 to which the collision load is applied toward the outer side in the width direction can be more reliably suppressed, and the collision load can be more reliably dispersed.

[0235] In addition, the subframe 1 of the present embodiment further comprises: a first vehicle body mounting member 60, which is provided on one side in the width direction to protrude upward in the vertical direction of the vehicle body relative to the first side beam 110 and the cross beam 10, and is provided with a first middle vehicle body mounting portion A3 between the first front vehicle body mounting portion A1 and the first rear vehicle body mounting portion A5 in the front-rear direction; and a second vehicle body mounting member 80, which is provided on the other side in the width direction to protrude upward in the vertical direction relative to the second side beam 150 and the cross beam 10, and is provided with a second front vehicle body mounting portion A2 and a second middle vehicle body mounting portion A3 between the first front vehicle body mounting portion A1 and the first rear vehicle body mounting portion A5 in the front-rear direction. The second middle body mounting portion A4 between the second rear body mounting portion A6, the connecting portion J1 of the second cross beam 240 connected to the first side beam 110 is configured to be closer to the first front body mounting portion A1 than the first middle body mounting portion A3, and the connecting portion J2 of the second cross beam 240 connected to the second side beam 150 is configured to be closer to the second front body mounting portion A2 than the second middle body mounting portion A4, thereby more reliably connecting the side beams 110, 150, thereby more reliably suppressing unnecessary deformation of the side beams 110, 150 to the outside in the width direction.

[0236] In addition, the types, shapes, arrangements, numbers, etc. of the components of the present invention are not limited to the above-mentioned embodiments, and can of course be appropriately changed without departing from the gist of the invention, for example, the components can be appropriately replaced with elements having equivalent effects.

[0237] Industrial Applicability

[0238] As described above, the present invention can provide a vehicle subframe that can suppress unnecessary deformation of a side member during a frontal collision of the vehicle and thereby exhibit desired collision performance. Therefore, due to its general and universal nature, it is expected to be widely used in the field of subframes of mobile bodies such as vehicles.

Claims

1. A vehicle subframe, mounted on a vehicle body, comprising: A first side member extending in the front-rear direction of the vehicle body and having a first front vehicle body mounting portion on the front side in the front-rear direction and a first rear vehicle body mounting portion on the rear side in the front-rear direction; a second side member extending in the front-rear direction of the vehicle body and arranged opposite to the first side member in the width direction of the vehicle body, and having a second front vehicle body mounting portion on the front side and a second rear vehicle body mounting portion on the rear side; and a first cross beam extending in the width direction and connecting the first side beam and the second side beam, The first side beam has a first extension portion that deflects and extends toward one outer side in the width direction as it goes from the rear direction side to the front direction side. The second side beam has a second extension portion that deflects and extends toward the outer side in the other direction of the width direction as it goes from the rear direction side to the front direction side. The vehicle subframe further includes a second cross member that is opposed to the first cross member on the front side and connects a first portion of the first extension portion that is deflected more toward the outer side in the one direction of the width direction and a second portion of the second extension portion that is deflected more toward the outer side in the other direction of the width direction. The first side beam has a first front curved portion on the front side that is bent and deformed in a manner that is convex to the upward direction side when the vehicle is hit head-on, and has a first rear curved portion on the rear side that is bent and deformed in a manner that is convex to the downward direction side when the vehicle is hit head-on. The second side beam has a second front curved portion on the front side that is bent and deformed in a manner that is convex to the upward direction side during the head-on collision, and has a second rear curved portion on the rear side that is bent and deformed in a manner that is convex to the downward direction side during the head-on collision. The second cross beam is connected to the first portion between the first front curved portion and the first rear curved portion of the first side beam, and is connected to the second portion between the second front curved portion and the second rear curved portion of the second side beam, The first side beam comprises an upper part and / or a lower part, wherein: The upper member comprises: an inclined portion, which is provided between the front end portion and the rear end portion of the upper member and is an intermediate portion of the upper wall portion of the upper member that descends toward the rear direction in a manner that begins to descend at the first front curved portion and ends to descend at the first rear curved portion and extends in a straight line; and a recessed portion that spans the first rear curved portion and a predetermined portion on the front side of the inclined portion of the upper member. The lower component comprises: an inclined portion, which is provided between the front end portion and the rear end portion of the lower component and is an intermediate portion in the bottom wall portion of the lower component that descends toward the rear direction and extends in a straight line in a manner starting to descend at the first front curved portion and ending to descend at the first rear curved portion; and a recessed portion that spans the first rear curved portion in the inclined portion of the lower component and a specified portion that is closer to the front direction than the first rear curved portion.

2. The vehicle subframe according to claim 1, wherein: The connection portion of the second beam connected to the first portion includes a first enlarged portion, the length of the first enlarged portion in the front-rear direction increasing as it goes toward the one side in the width direction. The connection portion of the second beam connected to the second portion includes a second enlarged portion whose length in the front-rear direction increases as it goes toward the other side in the width direction.

3. The vehicle subframe according to claim 2, wherein: In the first enlarged portion, at least one of the wall portion on the front side and the wall portion on the rear side of the first enlarged portion extends in the front-rear direction. In the second enlarged portion, at least one of a wall portion on the front direction side and a wall portion on the rear direction side of the second enlarged portion extends in the front-rear direction.

4. The vehicle subframe according to any one of claims 1 to 3, wherein: The vehicle subframe includes: a first vehicle body mounting member, which is provided on one side in the width direction and projects upwardly in the up-down direction of the vehicle body relative to the first side member and the first cross member, and has a first intermediate vehicle body mounting portion between the first front vehicle body mounting portion and the first rear vehicle body mounting portion in the front-rear direction; and a second vehicle body mounting member, which is provided on the other side in the width direction and projects upwardly in the up-down direction relative to the second side member and the first cross member, and has a second intermediate vehicle body mounting portion between the second front vehicle body mounting portion and the second rear vehicle body mounting portion in the front-rear direction, The connection portion of the second cross member connected to the first portion is arranged closer to the first front vehicle body mounting portion than to the first middle vehicle body mounting portion. A connection portion of the second cross member connected to the second portion is arranged closer to the second front vehicle body mounting portion than to the second middle vehicle body mounting portion.

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