JP7381327B2 - vehicle frame structure - Google Patents

Description

The present invention relates to a vehicle frame structure.

Conventionally, a vehicle is known that includes a chassis frame, a cab attached to the chassis frame, and a loading platform attached to the chassis frame behind the cab (for example, see Patent Document 1).

JP 2019-151199 Publication

In the above vehicle, input from the front wheels and rear wheels and the support loads of the cab and cargo bed may be applied to the chassis frame in different directions and sizes. Therefore, reinforcement is applied between the front wheels and the rear wheels in the frame to improve the rigidity characteristics.

Here, for example, if the assumed design value of the load applied to the pair of left and right side rails in the frame structure differs depending on how the vehicle is used at the destination, multiple reinforcing members are used for each assumed load value. If you use them properly, the number of specifications will increase. As a result, various costs may increase and productivity may deteriorate.

An object of the present invention is to provide a frame structure for a vehicle in which the rigidity characteristics of a side rail can be changed without using different reinforcing members.

A vehicle frame structure according to one aspect of the present invention includes a first bottom plate that intersects in the vehicle width direction and a pair of first side plates that stand up from both ends of the first bottom plate in the vehicle vertical direction and face each other. A frame structure for a vehicle in which a pair of side rails are installed side by side in the vehicle width direction, and the side rails are attached to the first bottom plate so as to be located in the space within the frame between the pair of first side plates, and are arranged in a predetermined direction in the longitudinal direction of the vehicle. The reinforcing member includes a second bottom plate fixed to the first bottom plate, and a pair of second side plates that stand up from both ends of the second bottom plate in the vehicle vertical direction and face each other. , and on at least one side of the reinforcing member in the vehicle longitudinal direction, the second side plate is not fixed to the first side plate but is spaced apart from the first side plate at a predetermined interval, and the predetermined interval is in the vehicle vertical direction. A predetermined severe condition is an interval at which the side rail can be deformed within an elastic range within the extension length in the longitudinal direction of the vehicle when an expected load is applied to the side rail.

In the vehicle frame structure according to one aspect of the present invention, on at least one side of the reinforcing member in the vehicle longitudinal direction, the second side plate is not fixed to the first side plate but is spaced apart from the first side plate at a predetermined interval. . The predetermined interval is an interval at which the side rail can be deformed within an elastic range within the extended length in the longitudinal direction of the vehicle when a predetermined severe input expected load in the vertical direction of the vehicle acts on the side rail. Therefore, when a severe condition input expected load acts on the side rail, the first side plate and the second side plate may come into contact with each other due to bending elastic deformation of the side rail in a plane along the first bottom plate. When the first side plate and the second side plate come into contact, force can be substantially transmitted between the first side plate and the second side plate at the contact point, and the rigidity characteristics of the side rail change. Therefore, according to the frame structure of the vehicle, it is possible to change the rigidity characteristics of the side rail without using different reinforcing members.

In one embodiment, the frame structure of the vehicle includes a third bottom plate that is arranged in a space within the frame and intersects in the vehicle width direction, and a pair of third side plates that stand up from both ends of the third bottom plate in the vehicle vertical direction and face each other. The vehicle further includes an inner rail extending in the longitudinal direction of the vehicle. The third side plate may be joined to the surface of the first side plate on the frame inner space side. In this case, the inner rail further improves the bending rigidity in the plane along the first bottom plate.

In one embodiment, the second side plate extends in the vehicle width direction and reaches between the third side plates, and may not be fixed to the third side plate but may be spaced apart from the third side plate at a predetermined interval. In this case, when the expected severe condition input load acts on the side rail, the second side plate and the third side plate come into contact with each other due to the bending elastic deformation of the side rail in the plane along the first bottom plate. Stiffness properties can be changed.

In one embodiment, the side rails include a front side rail that is arranged on the front side in the longitudinal direction of the vehicle and supports the front wheels and the cab, and a front side rail that is connected to the front side rail and arranged on the rear side in the longitudinal direction of the vehicle to support the rear wheels. and a rear side rail, and the reinforcing member may be attached to a connection location between the front side rail and the rear side rail. In this case, it is possible to change the rigidity characteristics of the side rails at connection points where stress due to the support loads of the front wheels, cab, and rear wheels tends to concentrate.

In one embodiment, on the front side of the reinforcing member in the vehicle longitudinal direction, the second side plate is not fixed to the first side plate of the front side rail and is spaced apart from the first side plate, and the second side plate is spaced apart from the first side plate of the front side rail. On the rear side, the second side plate may be fixed to the first side plate of the rear side rail. In this case, the first side plate and the third side plate of the front side rail are in contact with each other, so that the rigidity characteristics of the side rail can be changed.

According to the present invention, it is possible to change the rigidity characteristics of the side rail without using different reinforcing members.

FIG. 1 is a schematic plan view of a frame structure of a vehicle according to an embodiment. 2 is a schematic side view of the frame structure of the vehicle of FIG. 1. FIG. FIG. 2 is a side view of a connecting portion of the frame structure of the vehicle shown in FIG. 1; (a) is a diagram showing a cross section taken along line AA in FIG. 3. (b) is a diagram showing a cross section taken along line BB in FIG. 3. (c) is a diagram showing a cross section taken along line CC in FIG. 3. FIG. 2 is a side view of a reinforcing member in the frame structure of the vehicle shown in FIG. 1; FIG. 6 is a bottom view of the reinforcing member of FIG. 5; FIG. 3 is a diagram illustrating changes in rigidity characteristics.

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, the front-back direction, the left-right direction, and the up-down direction mean the vehicle traveling direction, the vehicle width direction, and the vehicle up-down direction, respectively. In each figure, direction F corresponds to the front, direction L corresponds to the vehicle width direction (left side in the vehicle traveling direction), and direction U corresponds to upward.

FIG. 1 is a schematic plan view of a vehicle frame structure 10 according to an embodiment. FIG. 2 is a schematic side view of the vehicle frame structure 10. As shown in FIGS. 1 and 2, the vehicle 1 includes a vehicle frame structure 10. As shown in FIGS. The frame structure 10 of the vehicle includes a pair of side rails 11 that extend in the longitudinal direction of the vehicle and are provided side by side in the vehicle width direction, and a plurality of cross members 12 that extend in the vehicle width direction and connect the left and right side rails 11. A frame structure 100 is provided. The pair of side rails 11 have substantially symmetrical shapes on the left and right sides.

The pair of side rails 11 are provided with a front wheel 2 located on the front side in the longitudinal direction of the vehicle, and a rear wheel 3 located on the rear side in the longitudinal direction of the vehicle, via a suspension device (not shown) such as a leaf spring, for example. is installed. The side rail 11 is a long metal member, and is made of steel, for example. The side rail 11 has a front side rail 20 on the front side in the vehicle longitudinal direction and a rear side rail 30 on the rear side in the vehicle longitudinal direction. The front side rail 20 is arranged on the front side in the longitudinal direction of the vehicle and supports the front wheels 2 and the cab 4. The rear side rail 30 is arranged on the rear side in the longitudinal direction of the vehicle and supports the rear wheel 3. The rear end portion of the front side rail 20 and the front end portion of the rear side rail 30 are connected to each other at a connection point 13 and are integrated.

FIG. 3 is a side view of the connection point 13 of the vehicle frame structure 10. FIG. 4(a) is a diagram showing a cross section taken along line AA in FIG. FIG. 4(b) is a diagram showing a cross section taken along line BB in FIG. FIG. 4(c) is a diagram showing a cross section taken along line CC in FIG. The pair of side rails 11 have substantially symmetrical shapes on the left and right sides, and in FIGS. 3 and 4, the connection point 13 on the right side in the vehicle traveling direction is illustrated. The connection point 13 on the left side in the vehicle traveling direction can have a symmetrical configuration with respect to the center of the vehicle, so a detailed description thereof will be omitted (the same applies in FIGS. 5 and 6).

As shown in FIGS. 3 and 4, the side rail 11 includes a first bottom plate 11a that intersects in the vehicle width direction, and a pair of first side plates that stand up from both ends 11b of the first bottom plate 11a in the vehicle vertical direction and face each other. 11c.

Specifically, the front side rail 20 includes a first bottom plate 21 that intersects in the vehicle width direction, and a pair of first side plates 23 that stand up from both ends 22 of the first bottom plate 21 in the vehicle vertical direction and face each other. are doing. The pair of first side plates 23 are, for example, formed in the same shape and stand vertically from the first bottom plate 21 . As a result, the front side rail 20 has a substantially U-shape (substantially U-shape) in cross section perpendicular to the longitudinal direction. The front side rail 20 can be formed, for example, by bending a flat steel plate in the width direction. The front side rail 20 has a thickness of, for example, about 4 to 5 mm. For example, the front side rail 20 is oriented to open inward in the vehicle width direction (IN direction in the figure) when viewed as a single unit, and an intraframe space S is formed between the pair of first side plates 23.

Further, the rear side rail 30 includes a first bottom plate 31 that intersects in the vehicle width direction, and a pair of first side plates 33 that stand up from both ends 32 of the first bottom plate 31 in the vehicle vertical direction and face each other. The pair of first side plates 33 are formed, for example, in the same shape, and stand upright from the first bottom plate 21 . As a result, the rear side rail 30 has a substantially U-shape (substantially U-shape) in cross section perpendicular to the longitudinal direction. The rear side rail 30 can be formed, for example, by bending a flat steel plate in the width direction. The rear side rail 30 has a thickness of, for example, about 4 to 5 mm. For example, the rear side rail 30 is oriented to open inward in the vehicle width direction (IN direction in the figure) when viewed as a single unit.

An inner rail 50 is arranged in a frame interior space S surrounded by the front side rails 20. The inner rail 50 has a third bottom plate 51 that intersects in the vehicle width direction, and a pair of third side plates 53 that stand up from both ends 52 of the third bottom plate 51 in the vehicle vertical direction and face each other, and extend in the vehicle longitudinal direction. There is. The inner rail 50 is open outward in the vehicle width direction, for example. The third bottom plate 51 includes an inclined part 51a that extends in a direction opposite to the upright direction of the third side plate 53 as it approaches both ends 52 in the vehicle vertical direction, except for a rear part in the longitudinal direction of the vehicle. Since the third bottom plate 51 is offset toward the center of the intra-frame space S by the inclined portion 51a, the space outside the third bottom plate 51 can be used as a space for, for example, wiring a harness or the like. The third side plate 53 is joined to the surface 23a of the first side plate 23 on the frame inner space S side. The inner rail 50 can be formed, for example, by press-molding a steel plate. The inner rail 50 has a thickness of, for example, about 3 to 4 mm. For example, the inner rail 50 is oriented to open outward in the vehicle width direction (in the direction opposite to IN in the figure) when viewed as a single unit.

As shown in FIG. 3, the vehicle frame structure 10 includes a reinforcing member 40 attached to the side rail 11. In this embodiment, the reinforcing member 40 is attached to the connection point 13 between the front side rail 20 and the rear side rail 30. The reinforcing member 40 extends with a predetermined length in the longitudinal direction of the vehicle. The reinforcing member 40 is attached to the first bottom plate 11a of the side rail 11 so as to be located in the frame internal space S.

FIG. 5 is a side view of the reinforcing member 40 in the frame structure 10 of the vehicle. FIG. 6 is a bottom view of the reinforcing member 40. A reinforcing member 40 attached to the right side rail 11 is shown in FIGS. 5 and 6. Note that the reinforcing member 40 attached to the left side rail 11 has a substantially symmetrical shape in the vehicle width direction compared to the reinforcing member 40 in FIGS. 5 and 6.

As shown in FIGS. 5 and 6, the reinforcing member 40 has a second bottom plate 41 fixed to the first bottom plate 21 of the front side rail 20, and a second bottom plate 41 that stands up from both ends 42 of the second bottom plate 41 in the vehicle vertical direction. A pair of opposing second side plates 43 are included. The pair of second side plates 43 stand vertically from the second bottom plate 41. As a result, the reinforcing member 40 has a substantially U-shape (substantially U-shape) in cross section perpendicular to the longitudinal direction. The second side plate 43 extends in the vehicle width direction. The reinforcing member 40 has a thickness of, for example, about 4 to 5 mm. For example, the reinforcing member 40 is attached to the first bottom plate 21 of the front side rail 20 so as to open inward in the vehicle width direction (IN direction in the figure) when viewed as a single unit.

The reinforcing member 40 here improves the bending rigidity of the front side rail 20 in a plane along the first bottom plate 21 by being attached to the first bottom plate 21 of the front side rail 20. For example, the reinforcing member 40 includes a plurality of nuts 44 joined to the second bottom plate 41. The reinforcing member 40 is attached to the first bottom plate 21 by screwing the bolt 45 into the nut 44 (see FIGS. 4(b) and 4(c)). For example, the reinforcing member 40 has a plurality of through holes 46 formed in the second bottom plate 41. The through hole 46 exposes the first bottom plate 21 of the front side rail 20. The reinforcing member 40 is attached to the first bottom plate 21 by fillet welding the inner edge of the through hole 46 and the first bottom plate 21 (see FIG. 4(a)). The number and arrangement of the nuts 44 and the number and arrangement of the through holes 46 can be determined depending on the bonding strength of the front side rail 20 with the first bottom plate 21, for example, by a design method using simulation.

For example, the reinforcing member 40 has notches 47 formed at the front and rear ends of the second bottom plate 41 in the vehicle longitudinal direction. The reinforcing member 40 is attached to the first bottom plate 21 by fillet welding the edge of the notch 47 at the front end and the first bottom plate 21 of the front side rail 20. The reinforcing member 40 is attached to the first bottom plate 31 by fillet welding the edge of the notch 47 at the rear end and the first bottom plate 31 of the rear side rail 30 . The shape and arrangement of the notch 47 are determined by a design method using simulation, for example, depending on the bonding strength between the front side rail 20 and the first bottom plate 21 and the bonding strength between the rear side rail 30 and the first bottom plate 31. be able to.

Note that the fillet welding here may be performed prior to the screwing of the nut 44 and the bolt 45, for example, in order to effectively exert the axial force of the screwing.

As shown in FIGS. 4A to 4C, in the frame structure 10 of the vehicle, the second bottom plate 41 of the reinforcing member 40 is attached to the first bottom plate 21 of the front side rail 20 so as to run along it. On the front side of the connection point 13 in the longitudinal direction of the vehicle, the third side plate 53 of the inner rail 50 extends in the vehicle width direction and reaches between the first side plates 23 of the front side rail 20 . On the rear side of the connection point 13 in the longitudinal direction of the vehicle, the third side plate 53 of the inner rail 50 extends in the vehicle width direction and extends between the first side plate 23 of the front side rail 20 and the first side plate 33 of the rear side rail 30. has reached.

Further, the second side plate 43 of the reinforcing member 40 extends in the vehicle width direction and reaches between the third side plates 53 of the inner rail 50. The second side plate 43 of the reinforcing member 40 and the third side plate 53 of the inner rail 50 overlap in their respective distal end portions in the vehicle width direction when viewed in cross section. In such a configuration, the inner rail 50 is attached to the front side rail 20 after the reinforcing member 40 is attached to the front side rail 20. The third side plate 53 of the inner rail 50 is inserted between the first side plate 23 of the front side rail 20 and the second side plate 43 of the reinforcing member 40, and is attached to the surface 23a of the first side plate 23 on the frame inner space S side. Joined. Therefore, the reinforcing member 40 will be accommodated in the frame internal space S.

As shown in FIGS. 3 and 5, on the rear side of the reinforcing member 40 in the longitudinal direction of the vehicle, the width dimension (dimension in the vertical direction of the vehicle) that intersects with the longitudinal direction of the reinforcing member 40 is the width dimension of the pair of front side rails 20. The distance is approximately equal to the distance between the first side plates 23. The second side plate 43 is fixed to the first side plate 33 of the rear side rail 30 on the rear side of the reinforcing member 40 in the longitudinal direction of the vehicle. As shown in FIG. 4B, at the connection point 13, the front side rail 20 and the rear side rail 30 are connected, and the rear end portion of the reinforcing member 40 is also connected. At the connection point 13, in order from the center side of the frame internal space S, the second side plate 43 of the reinforcing member 40, the third side plate 53 of the inner rail 50, the first side plate 23 of the front side rail 20, and the first side plate of the rear side rail 30. The side plates 33 are stacked on top of each other and are fastened to each other by rivets inserted into through holes coaxially formed in each member.

As shown in FIG. 3, on the front side of the reinforcing member 40 in the longitudinal direction of the vehicle, the width dimension (dimension in the vertical direction of the vehicle) that intersects with the longitudinal direction of the reinforcing member 40 is the width of the first side plate of the pair of front side rails 20. 23 is set smaller than the distance between each other. On the front side of the reinforcing member 40 in the longitudinal direction of the vehicle, the width dimension that intersects with the longitudinal direction of the reinforcing member 40 is smaller than the distance between the pair of third side plates 53 of the inner rail 50 (the distance between the surfaces 53a). ing. That is, in a state where the reinforcing member 40 is attached to the first bottom plate 21, the second side plate 43 is not fixed to the first side plate 23 of the front side rail 20 on the front side of the reinforcing member 40 in the longitudinal direction of the vehicle. 11c, and is not fixed to the third side plate 53 of the inner rail 50, but is spaced apart from the third side plate 53.

As shown in FIGS. 3, 4(a) and 4(c), on at least one side (here, the front side) in the vehicle longitudinal direction of the reinforcing member 40, the first side plate 23 of the front side rail 20 and the reinforcing The second side plate 43 of the member 40 is spaced apart from each other at a predetermined interval. This predetermined interval is an interval at which the side rail 11 can be deformed within an elastic range within the extended length in the longitudinal direction of the vehicle when a predetermined severe condition input assumed load in the vehicle vertical direction acts on the side rail 11. The expected severe condition input load is an expected value of a design load that can be input to the side rail 11 and is assumed to be likely to occur under severe conditions. Severe conditions mean severe design conditions for the side rails 11. For example, considering the state of road maintenance and how the vehicle 1 is used (for example, the risk of being used in an overloaded state), when comparing the expected input load from the road surface while driving, Vehicle 1 for emerging countries is more likely to fall under the severe condition. The severe condition input expected load may be a load that is increased by a certain percentage from the expected input load to the side rail 11 in the vehicle 1 for developed countries, taking into account the above-mentioned severity.

With this configuration, in the vehicle frame structure 10, the rigidity characteristics of the side rails change depending on the magnitude of the load input to the side rails 11. FIG. 7 is a diagram illustrating changes in rigidity characteristics. The horizontal axis in FIG. 7 indicates the load input to the side rail 11. The vertical axis in FIG. 7 indicates the rigidity of the side rail 11. The input of load to the side rail 11 here corresponds to, for example, a bending load (bending stress) on the front side rail 20 within the plane of the first bottom plate 21. The rigidity of the side rail 11 means, for example, the bending rigidity of the front side rail 20 in a plane along the first bottom plate 21.

As shown in FIG. 7, when the magnitude of the load input to the side rail 11 increases from a load smaller than the input F1 to the input F1, the rigidity of the side rail 11 is approximately constant at the rigidity G1. This change in rigidity corresponds to the fact that the second side plate 43 and the third side plate 53 are not yet in contact even with bending elastic deformation of the side rail 11 in the plane along the first bottom plate 11a.

On the other hand, when the magnitude of the load input to the side rail 11 increases from a load greater than input F1 to input F2, the rigidity of the side rail 11 increases from rigidity G1 to rigidity G2. This change in rigidity is caused by the bending elastic deformation of the side rail 11 in the plane along the first bottom plate 11a, which causes the second side plate 43 and the third side plate 53 to start contacting each other, causing elasticity of each member near the contact point. This corresponds to the transition of deformation until it reaches an equilibrium state. After that, when the magnitude of the load input to the side rail 11 increases to a load greater than or equal to the input F2, the rigidity of the side rail 11 becomes a substantially constant rigidity G2. This change in rigidity corresponds to a state in which force can be substantially transmitted between the second side plate 43 and the third side plate 53, which are in an equilibrium state at the contact point.

[Action and effect]
As described above, in the vehicle frame structure 10 according to the present embodiment, on at least one side (front side) of the reinforcing member 40 in the longitudinal direction of the vehicle, the second side plate 43 of the reinforcing member 40 is connected to the first side plate 11c of the side rail 11 ( It is not fixed to the first side plate 23) of the front side rail 20. Further, the second side plate 43 of the reinforcing member 40 extends in the vehicle width direction and reaches between the third side plates 53 of the inner rail 50, and is not fixed to the third side plate 53 of the inner rail 50. 53 at a predetermined interval. This predetermined interval is an interval at which the side rail 11 can be deformed within an elastic range within the extended length in the longitudinal direction of the vehicle when a predetermined severe condition input assumed load in the vehicle vertical direction acts on the side rail 11. Therefore, when a severe condition input expected load acts on the side rail 11, the second side plate 43 and the third side plate 53 may come into contact with each other due to the bending elastic deformation of the side rail 11 in the plane along the first bottom plate 11a. When the second side plate 43 and the third side plate 53 come into contact, force can be substantially transmitted between the second side plate 43 and the third side plate 53 at the contact location, and the rigidity characteristics of the side rail 11 change. Therefore, according to the vehicle frame structure 10, it is possible to change the rigidity characteristics of the side rail 11 without using different reinforcing members 40.

The frame structure 10 of the vehicle includes a third bottom plate 51 disposed in the frame interior space S and intersecting in the vehicle width direction, and a pair of third side plates 53 that stand up from both ends 52 of the third bottom plate 51 in the vehicle vertical direction and face each other. The vehicle further includes an inner rail 50 that extends in the longitudinal direction of the vehicle. The third side plate 53 is joined to the surface 23a of the first side plate 11c on the frame inner space S side. Such inner rail 50 further improves the bending rigidity in the plane along the first bottom plate 11a.

Note that the front side rail 20 is oriented to open inward in the vehicle width direction (IN direction in the figure) when viewed as a single unit. The reinforcing member 40 is attached to the first bottom plate 21 of the front side rail 20 so as to open inward in the vehicle width direction (IN direction in the figure) when viewed as a single unit. The inner rail 50 is attached to the first side plate 23 of the front side rail 20 in such a direction that it opens outward in the vehicle width direction (the direction opposite to IN in the figure) when viewed as a single unit. In such a configuration, the third side plate 53 of the inner rail 50 is inserted between the first side plate 23 of the front side rail 20 and the second side plate 43 of the reinforcing member 40, and the third side plate 53 of the inner rail 50 is inserted into the frame of the first side plate 23. It is joined to the surface 23a on the space S side. Therefore, after the reinforcing member 40 is attached to the front side rail 20, the inner rail 50 can be easily attached to the front side rail 20. As a result, if there is a destination that does not require the reinforcing member 40 due to rigidity characteristics, for example, the frame structure 100 to which the reinforcing member 40 is attached and the frame structure to which the reinforcing member 40 is not attached, It is possible to standardize the installation process of the inner rail 50.

In the frame structure 10 of the vehicle, the side rail 11 is connected to a front side rail 20 that is disposed on the front side in the vehicle longitudinal direction and supports the front wheels 2 and the cab 4, and is connected to the front side rail 20, and is connected to the front side rail 20 on the rear side in the vehicle longitudinal direction. A rear side rail 30 is arranged to support the rear wheel 3. The reinforcing member 40 is attached to the connection point 13 between the front side rail 20 and the rear side rail 30. Thereby, the rigidity characteristics of the side rail 11 at the connection point 13 where stress due to the support loads of the front wheel 2, cab 4, and rear wheel 3 are likely to be concentrated can be changed.

In the vehicle frame structure 10, on the front side of the reinforcing member 40 in the vehicle longitudinal direction, the second side plate 43 is not fixed to the first side plate 23 of the front side rail 20 but is spaced apart from the first side plate 23. The second side plate 43 is fixed to the first side plate 33 of the rear side rail 30 on the rear side of the reinforcing member 40 in the longitudinal direction of the vehicle. Thereby, the first side plate 23 and the third side plate 53 of the front side rail 20 come into contact with each other, so that the rigidity characteristics of the side rail 11 can be changed.

Note that in the frame structure 10 of the vehicle, the reinforcing member 40 is housed in the intra-frame space S. Therefore, for example, compared to the size of the external shape of the front side rail 20 and inner rail 50 when the reinforcing member 40 is not provided, the size of the external shape of the front side rail 20 and the inner rail 50 when the reinforcing member 40 is provided is can be maintained. As a result, it is possible to suppress the influence of whether or not the reinforcing member 40 is attached on the mountability of auxiliary equipment, exhaust equipment, etc. that are attached along the outer shapes of the front side rail 20 and the inner rail 50.

[Modified example]
Although the embodiments according to the present invention have been described above, the present invention is not limited to the embodiments described above.

In the above embodiment, the second side plate 43 of the reinforcing member 40 and the third side plate 53 of the inner rail 50 have overlapping tip portions in the cross-sectional view in the vehicle width direction, but the present invention is not limited to this. Not done. For example, the second side plate 43 of the reinforcing member 40 may extend in the vehicle width direction to such an extent that it does not reach between the third side plates 53 of the inner rail 50. In other words, the second side plate 43 of the reinforcing member 40 and the third side plate 53 of the inner rail 50 do not have to have their respective distal end areas overlapping in the vehicle width direction when viewed in cross section. In this case, the second side plate 43 of the reinforcing member 40 may be spaced apart from the first side plate 23 of the front side rail 20 at a predetermined interval instead of the third side plate 53 of the inner rail 50.

In the above embodiment, the inner rail 50 is attached to the front side rail 20 and constitutes the side rail 11 together with the front side rail 20, but the inner rail 50 may be omitted.

In the above embodiment, the pair of first side plates 23 of the front side rail 20 are formed to have the same shape, but the present invention is not limited thereto. Although the pair of first side plates 33 of the rear side rail 30 are formed in the same shape, the present invention is not limited thereto. Further, although the rear side rail 30 is disposed outside the front side rail 20, the present invention is not limited thereto. In short, the reinforcing member 40 is disposed immediately inside the side rail 11 (inner rail 50, front side rail 20, or rear side rail 30), and the second side plate 43 of the reinforcing member 40 The third side plate 53, the first side plate 23 of the front side rail 20, or the first side plate 33 of the rear side rail 30 may be spaced at a predetermined interval.

In the above embodiment, the pair of side rails 11 have a substantially symmetrical shape on the left and right sides, but may be asymmetrical.

In the embodiment described above, the side rail 11 includes a front side rail 20 on the front side in the longitudinal direction of the vehicle and a rear side rail 30 on the rear side in the longitudinal direction of the vehicle, which are integrated at the connection point 13. However, the front and rear side rails 11 may be integrated without being divided into front and rear sections. In this case, a reinforcing member 40 may be provided at a location corresponding to the connection location 13.

In the above embodiment, the second side plate 43 of the reinforcing member 40 is fixed to the first side plate 33 of the rear side rail 30 on the rear side of the reinforcing member 40 in the longitudinal direction of the vehicle. but not limited to. The reinforcing member 40 may be fixed at the front side in the longitudinal direction of the vehicle, or at the center in the longitudinal direction of the vehicle. In short, on at least one side of the reinforcing member 40 in the vehicle longitudinal direction, the second side plate 43 of the reinforcing member 40 is not fixed to the first side plate 11c of the side rail 11, but is spaced apart from the first side plate 11c at a predetermined interval. All you have to do is stay there.

DESCRIPTION OF SYMBOLS 1... Vehicle, 2... Front wheel, 3... Rear wheel, 4... Cab, 10... Frame structure, 11... Side rail, 11a, 21, 31... First bottom plate, 11b, 22, 32, 42, 52... Vehicle vertical direction Both ends, 11c, 23, 33...First side plate, 13...Connection point, 20...Front side rail (side rail), 23a...Surface, 30...Rear side rail (side rail), 40...Reinforcement member, 41...Second bottom plate , 43... Second side plate, 50... Inner rail (side rail), 51... Third bottom plate, 53... Third side plate, S... Frame internal space.

Claims (5)

A pair of side rails are provided in the vehicle width direction and extend in the vehicle longitudinal direction and have a first bottom plate that intersects in the vehicle width direction and a pair of first side plates that stand up from both ends of the first bottom plate in the vehicle vertical direction and oppose each other. A frame structure of a vehicle that is
a reinforcing member attached to the first bottom plate so as to be located in a space within the frame between the pair of first side plates, and extending in a predetermined length in the longitudinal direction of the vehicle;
The reinforcing member is
a second bottom plate fixed to the first bottom plate;
a pair of second side plates standing up from both ends of the second bottom plate in the vehicle vertical direction and facing each other;
The second side plate is fixed to the first side plate on either the front side, the rear side, or the center part of the reinforcing member in the longitudinal direction of the vehicle,
On at least one side of the reinforcing member in the longitudinal direction of the vehicle, the second side plate is not fixed to the first side plate and is spaced apart from the first side plate at a predetermined interval;
The predetermined interval is an interval at which the side rail can be deformed within an elastic range within the extension length in the vehicle longitudinal direction when a predetermined severe condition input expected load in the vehicle vertical direction acts on the side rail. the law of nature,
The load acting on the side rail causes bending elastic deformation in the side rail and the reinforcing member in a plane along the first bottom plate with reference to a position where the second side plate is fixed to the first side plate. It is a load along the vertical direction of the vehicle,
With the first bottom plate of the side rail and the second bottom plate of the reinforcing member fixed, a load acting on the side rail causes the first side plate and the second side plate to approach each other in the space within the frame. deformed so that
When the load acting on the side rail is less than the expected severe condition input load, the first side plate and the second side plate, which are close to each other, do not come into contact with each other,
A frame structure of a vehicle, wherein the first side plate and the second side plate, which are close to each other, come into contact when a load acting on the side rail is equal to or higher than the expected severe condition input load. The third bottom plate is arranged in the frame interior space and extends in the vehicle longitudinal direction, and includes a third bottom plate that intersects in the vehicle width direction, and a pair of third side plates that stand up from both ends of the third bottom plate in the vehicle vertical direction and face each other. Additionally equipped with an inner rail,
The third side plate is joined to a surface of the first side plate on the frame inner space side ,
When the load acting on the side rail is less than the severe condition input expected load, the first side plate and the third side plate that are close to each other do not contact,
2. The vehicle frame structure according to claim 1, wherein the first side plate and the third side plate, which are close to each other, come into contact when the load acting on the side rail is equal to or higher than the expected load input in the severe condition. The second side plate extends in the vehicle width direction and reaches between the third side plates, and is not fixed to the third side plate and is spaced apart from the third side plate at the predetermined interval. The frame structure of the vehicle according to item 2. The side rail is
a front side rail that is disposed on the front side of the vehicle in the longitudinal direction and supports the front wheels and the cab;
a rear side rail connected to the front side rail, disposed on the rear side in the longitudinal direction of the vehicle, and supporting a rear wheel;
4. The vehicle frame structure according to claim 1, wherein the reinforcing member is attached to a connection point between the front side rail and the rear side rail. On the front side of the reinforcing member in the longitudinal direction of the vehicle, the second side plate is not fixed to the first side plate of the front side rail and is spaced apart from the first side plate;
5. The vehicle frame structure according to claim 4, wherein the second side plate is fixed to the first side plate of the rear side rail on the rear side of the reinforcing member in the longitudinal direction of the vehicle.

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