Frame structure of vehicle

Abstract

A frame structure of a vehicle according to one embodiment of the present invention includes: a pillar having a hollow structure extending in a vertical direction of the vehicle; a side rail having a hollow structure extending in a front-rear direction of the vehicle; a cross member having a hollow structure extending in a width direction of the vehicle; and a linking plate. The side rail includes: an inner plate disposed on an inner side in the width direction; an outer plate disposed on an outer side in the width direction; an upper plate connecting an upper end of the inner plate and an upper end of the outer plate; and a lower plate connecting a lower end of the inner plate and a lower end of the outer plate, and has a rectangular cross-sectional shape with a cavity therein. The inner plate of the side rail has a slit extending in the vertical direction. The linking plate is inserted into the slit such that at least a part of the linking plate is disposed in the cavity in a state in which a thickness direction of the linking plate is directed in the front-rear direction. The side rail is welded to the linking plate along the slit, the cross member is welded to the linking plate, and the pillar is welded to the side rail or the linking plate.

Description

Vehicle Frame Structure

[0001] The present disclosure relates to a vehicle frame structure.

[0002] From the perspective of occupant protection, it is desirable to suppress deformation of the vehicle frame when a load is input to the vehicle from the side. As a technique for suppressing deformation of a vehicle, Patent Document 1 discloses a vehicle body structure including a pair of roof rails extending in the front-rear direction at an upper portion of the vehicle, a roof bow extending in the vehicle width direction at the upper portion of the vehicle and connecting the pair of roof rails, a cross member extending in the vehicle width direction at a lower portion of the vehicle and connecting the pair of roof rails, and a pair of pillars extending in the vertical direction on the left and right sides of the vehicle. A central reinforcing member having an upper end coupled to an upper end of the pillar and a lower end coupled to the cross member is provided inside the pillar. At the upper end of the central reinforcing member, a front-rear reinforcing member extending in the vehicle length direction and fixed to the roof rail is provided. A bulkhead disposed adjacent to the front-rear reinforcing member is fixed to the roof rail.

[0003] Japanese Unexamined Patent Publication No. 2020-83268

[0004] The above-described vehicle structure includes the central reinforcing member, the front-rear reinforcing member, and the bulkhead, so as to reinforce the connecting portions of the pillars, the roof rails and the roof bow, and suppress deformation of the vehicle during rollover. However, in this vehicle structure, large components such as the central reinforcing member, the front-rear reinforcing member and the bulkhead are added, which increases the manufacturing cost of the frame. In addition, the addition of these large components causes an increase in the weight of the vehicle.

[0005] Accordingly, an object of the present disclosure is to improve the strength of a vehicle frame structure with a simple configuration.

[0006] A vehicle frame structure according to one embodiment comprises a hollow pillar extending in the vertical direction of the vehicle, a hollow side rail extending in the longitudinal direction of the vehicle, a hollow cross member extending in the width direction of the vehicle, and a connecting plate. The side rail includes an inner plate positioned on the inside in the width direction, an outer plate positioned on the outside in the width direction, an upper plate connecting the upper end of the inner plate and the upper end of the outer plate, and a lower plate connecting the lower end of the inner plate and the lower end of the outer plate, and has a rectangular cross-section with a cavity inside. The inner plate of the side rail has a slit extending in the vertical direction, and the connecting plate is inserted into the slit such that at least a part of the connecting plate is positioned within the cavity with its thickness direction oriented in the longitudinal direction. The side rail is welded to the connecting plate along the slit, the cross member is welded to the connecting plate, and the pillar is welded to the side rail or the connecting plate.

[0007] When a vehicle rolls over, if a load is applied to the side rails or cross members, stress may concentrate on the side rails at the connection points, causing the side rails to lose their cross-sectional shape. In this case, the shape of the vehicle's frame structure may be distorted, potentially leading to a loss of survival space within the vehicle. In contrast, in the vehicle frame structure according to this embodiment, the side rails, cross members, and pillars are connected via connecting plates, thereby improving the overall strength of the frame. In particular, with the thickness direction of the connecting plate oriented in the front-rear direction, a portion of the connecting plate is positioned within the cavity of the side rail through a slit, so the side rail is reinforced by the connecting plate, suppressing deformation of the side rail's cross-section. As a result, distortion of the entire frame is suppressed, improving the strength and rigidity of the frame structure. This ensures occupant survival space and enhances the vehicle's crash safety. In other words, this frame structure allows for improved frame structure strength with a simple configuration using connecting plates, without the need to add large components.

[0008] The side rail is a roof rail connected to the upper end of the pillar, and the cross member is a roof cross member that supports the roof panel of the vehicle. The connecting plate has a first end face that extends in the width direction when viewed from the front-rear direction, and a second end face that extends in the vertical direction when viewed from the front-rear direction and is connected to the first end face. The first end face is welded to the lower plate within a cavity, and the second end face may be exposed from the roof cross member through a slit and welded to the end face of the roof cross member. In this case, since the roof rail and the roof cross member are welded to each other via the connecting plate, the strength of the connection can be increased and localized stress concentration can be prevented. In addition, welding along the first and second end faces of the connecting plate makes it easier to position the roof rail and roof cross member, and allows for more accurate welding, thus contributing to a reduction in manufacturing costs.

[0009] Viewed from the front and rear, the connecting plate has a rectangular shape with one corner cut out, and the connecting plate has a third end face extending vertically from the end of the first end face when viewed from the front and rear, a fourth end face extending horizontally from the end of the second end face when viewed from the front and rear, and a fifth end face extending in a direction inclined with respect to the width between the third and fourth end faces when viewed from the front and rear, and the third, fourth, and fifth end faces do not have to be welded to the roof rail. In this embodiment, since the third, fourth, and fifth end faces are not welded to the roof rail, the manufacturing efficiency of the frame structure can be increased.

[0010] The side rail is a floor rail connected to the pillar, the cross member is a floor cross member that supports the floor of the vehicle, the floor rail has a first slit which is a slit, and a second slit formed in at least one of the upper plate and the lower plate and extending in the width direction from the end of the first slit, the floor cross member has a third slit extending in the width direction from the end face of the floor cross member in the width direction, the pillar has a fourth slit extending vertically from the end face of the pillar in the vertical direction, the connecting plate includes a main body disposed in a cavity, a first rib protruding inward in the width direction from the main body through the first slit, and a second rib protruding vertically from the main body through the second slit, the first rib is inserted into the third slit, the second rib is inserted into the fourth slit, the floor rail is welded to the main body along the first and second slits, the floor cross member is welded to the first rib along the third slit, and the pillar is welded to the second rib along the fourth slit. In this case, the floor rail, floor cross member, and pillar are welded to each other via a connecting plate, thereby increasing the strength of the connection. Furthermore, welding each component along the first, second, and third slits makes it easier to position the floor rail, floor cross member, and pillar, and allows for more accurate welding, thus contributing to a reduction in manufacturing costs.

[0011] The vehicle may be a bus. In this embodiment, distortion of the bus's frame structure during a rollover can be suppressed.

[0012] According to various aspects of the present invention, the strength of the frame structure can be improved with a simple configuration.

[0013] This is a side view showing the frame structure of a vehicle according to one embodiment. This is a schematic diagram showing the annular frame. This is a perspective view showing the upper connecting part of the frame structure as seen from the outside of the vehicle. This is a cross-sectional view showing the upper connecting part of the frame structure. This is a perspective view showing the inner roof rail and two connecting plates in an exploded view. This is a perspective view showing the connected inner roof rail and two connecting plates. This is a perspective view showing the upper connecting part as seen from the inside of the vehicle. This is a perspective view showing the lower connecting part of the frame structure. This is a cross-sectional view showing the lower connecting part of the frame structure. This is a perspective view showing the upper pillar, lower pillar, floor rail and floor cross member in an exploded view. This is a perspective view showing the welding position between the floor rail and the connecting plate.

[0014] Embodiments of the present disclosure will be described below with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant descriptions will not be repeated.

[0015] Figure 1 is a side view showing a vehicle frame structure according to one embodiment. The vehicle frame structure 1 shown in Figure 1 is applied, for example, to a bus. In the following description, the three mutually orthogonal axial directions will be described as the "X direction," "Y direction," and "Z direction," respectively. The X direction is the left-right direction when viewing the vehicle from the rear, i.e., the width direction of the vehicle. The Y direction is the forward and backward direction of the vehicle, i.e., the longitudinal direction of the vehicle. The Z direction is the up-down direction of the vehicle.

[0016] As shown in Figure 1, the frame structure 1 comprises pillars 2, roof rails 3, roof cross members 4, floor rails 5, and floor cross members 6. The pillars 2, roof cross members 4, and floor cross members 6 form a gate-shaped annular frame 10 when viewed from the Y direction. Figure 2 is a schematic diagram of the annular frame 10. As shown in Figure 1, the frame structure 1 comprises a plurality of annular frames 10 arranged at intervals in the Y direction.

[0017] Pillars 2 are provided on the left and right sides of the vehicle and extend in the Z direction. The frame structure 1 includes a plurality of pillars 2 arranged at intervals in the Y direction. Pillars 2 have a hollow structure with a rectangular cross-section. Some of the plurality of pillars 2 may include upper pillars 2A and lower pillars 2B. The upper pillars 2A extend in the Z direction above the floor rails 5. The lower pillars 2B extend in the Z direction below the floor rails 5. The upper pillars 2A and lower pillars 2B are connected to each other via the floor rails 5.

[0018] The roof rails 3 are located on the upper part of the vehicle and extend in the Y direction. The roof rails 3 constitute side rails that extend in the front-rear direction of the vehicle. The frame structure 1 is equipped with a pair of roof rails 3 located on the left and right sides of the vehicle. The roof rails 3 are connected to the upper ends of a plurality of pillars 2. The roof rails 3 have a hollow structure with a rectangular cross-section.

[0019] The roof cross member 4 is located on the upper part of the vehicle and extends in the X direction. The roof cross member 4 constitutes a cross member that extends in the width direction of the vehicle. The frame structure 1 has a plurality of roof cross members 4 arranged at intervals in the Y direction. The plurality of roof cross members 4 support the roof panel of the vehicle. The roof cross member 4 has a hollow structure with a rectangular cross section. Both ends of the roof cross member 4 are connected to a pair of roof rails 3.

[0020] The floor rail 5 is located at the bottom of the vehicle and extends in the Y direction. The floor rail 5 constitutes the side rails that extend in the longitudinal direction of the vehicle. The frame structure 1 is equipped with a pair of floor rails 5 located on the left and right sides of the vehicle. The floor rail 5 is connected to the lower ends of a plurality of pillars 2 or upper pillars 2A. The upper end of the lower pillar 2B is connected to the floor rail 5 at a position corresponding to the lower end of the upper pillar 2A. The floor rail 5 has a hollow structure with a rectangular cross-section.

[0021] The floor cross member 6 is located at the bottom of the vehicle and extends in the X direction. The floor cross member 6 constitutes a cross member that extends in the width direction of the vehicle. The frame structure 1 has a plurality of floor cross members 6 arranged at intervals in the Y direction. The plurality of floor cross members 6 support the floor of the vehicle. The floor cross member 6 has a hollow structure with a rectangular cross section. Both ends of the floor cross member 6 are connected to a pair of floor rails 5.

[0022] The pillar 2, roof rail 3, and roof cross member 4 are connected at the upper connecting portion C1. Figure 3 is a perspective view showing the upper connecting portion C1. Figure 4 is a cross-sectional view showing the upper connecting portion C1. As shown in Figures 3 and 4, the pillar 2, roof rail 3, and roof cross member 4 are connected via one or more connecting plates. In the embodiments shown in Figures 3 and 4, the frame structure 1 is provided with two connecting plates 20 as one or more connecting plates.

[0023] As shown in Figure 3, the roof rail 3 has a rectangular cross-section with a cavity 3c inside and includes an inner plate 11, an outer plate 12, an upper plate 13, and a lower plate 14. The inner plate 11 is located on the inside of the vehicle in the X direction. The outer plate 12 is located on the outside of the vehicle in the X direction and faces the inner plate 11 in the X direction. The upper plate 13 connects the upper end of the inner plate 11 and the upper end of the outer plate 12. The lower plate 14 connects the lower end of the inner plate 11 and the lower end of the outer plate 12. The upper plate 13 and the lower plate 14 face each other in the Z direction.

[0024] The roof rail 3 may include an inner roof rail 3a and an outer roof rail 3b. The inner roof rail 3a has a substantially L-shaped cross-section and is located on the inside of the vehicle in the X direction. The inner roof rail 3a provides the inner plate 11 and the lower plate 14 of the roof rail 3. The outer roof rail 3b has a substantially L-shaped cross-section and is located on the outside of the vehicle in the X direction. The outer roof rail 3b provides the outer plate 12 and the upper plate 13 of the roof rail 3. The inner roof rail 3a and the outer roof rail 3b may each have flanges 15a and 15b extending in the X direction when viewed from the Y direction, and flanges 16a and 16b extending in the Z direction when viewed from the Y direction. The flanges 15a and 15b are connected to each other, and the flanges 16a and 16b are connected to each other, thereby forming a roof rail 3 with a rectangular cross-section.

[0025] Figure 5 is an exploded perspective view showing the inner roof rail 3a and the two connecting plates 20. As shown in Figure 5, the inner plate 11 of the inner roof rail 3a has a slit 11s extending in the Z direction. The slit 11s is a through hole that penetrates the inner plate 11 in its thickness direction. In the Y direction, the slit 11s has a width slightly wider than the thickness of the connecting plate 20. In the embodiment shown in Figure 5, the inner plate 11 has two slits 11s that are arranged side by side in the Y direction and extend in the Z direction parallel to each other.

[0026] The connecting plate 20 is a rigid plate. The connecting plate 20 is made of a metal such as high-tensile steel, iron, or aluminum alloy. The connecting plate 20 may have a polygonal planar shape. For example, as shown in Figure 5, the connecting plate 20 has a shape in which one corner of a rectangle is cut off, and has a pentagonal planar shape.

[0027] In the embodiment shown in Figure 5, the connecting plate 20 has a first end face 21, a second end face 22, a third end face 23, a fourth end face 24, and a fifth end face 25. The first end face 21 and the fourth end face 24 extend in the X direction when viewed from the Y direction. The second end face 22 and the third end face 23 extend in the Z direction when viewed from the Y direction. The fifth end face 25 extends in a direction inclined with respect to the X and Z directions when viewed from the Y direction. The first end face 21 and the second end face 22 intersect perpendicularly at one corner of the connecting plate 20. The first end face 21 and the third end face 23 intersect perpendicularly at another corner of the connecting plate 20. The second end face 22 and the fourth end face 24 intersect perpendicularly at yet another corner of the connecting plate 20. The fifth end face 25 intersects non-perpendicularly with the third end face 23 and the fourth end face 24.

[0028] The two connecting plates 20 are inserted into two slits 11s formed in the inner plate 11 of the roof rail 3, with their thickness directions oriented in the Y direction. That is, each of the two connecting plates 20 is positioned along the XZ plane. Here, as shown in Figure 6, the second end face 22 of the connecting plate 20 is exposed from the roof rail 3 through the slits 11s. The first end face 21, third end face 23, fourth end face 24, and fifth end face 25 of the connecting plate 20 are positioned within the cavity 3c of the roof rail 3. That is, at least a portion of the connecting plate 20 is positioned within the cavity 3c. As shown in Figure 3, the fifth end face 25 may be positioned spaced apart from the inner plate 11, outer plate 12, upper plate 13, and lower plate 14 of the roof rail 3.

[0029] As shown in Figure 6, the connecting plate 20 is welded to the inner surface of the lower plate 14 of the roof rail 3 via a weld joint W1. The weld joint W1 indicates the welding location between the connecting plate 20 and the lower plate 14 and extends in the X direction along the first end face 21 within the cavity 3c. That is, the first end face 21 of the connecting plate 20 is welded to the lower plate 14 within the cavity 3c. The connecting plate 20 is also welded to the inner surface of the inner plate 11 of the roof rail 3 via a weld joint W2. The weld joint W2 indicates the welding location between the connecting plate 20 and the inner plate 11 and extends in the Z direction along the slit 11s within the cavity 3c. On the other hand, the third end face 23, the fourth end face 24, and the fifth end face 25 are not welded to the roof rail 3. In the manufacturing process of the frame structure 1, after welding the inner roof rail 3a and the connecting plate 20, the inner roof rail 3a and the outer roof rail 3b are joined together. As a result, as shown in Figure 3, the connecting plate 20 is housed within the cavity 3c of the roof rail 3.

[0030] Figure 7 is a perspective view of the upper connecting portion C1 as seen from inside the vehicle. As shown in Figure 7, the connecting plate 20 is welded to the end face 4a of the roof cross member 4 via a weld W3. The weld W3 indicates the welding location between the connecting plate 20 and the roof cross member 4 and extends in the Z direction along the slit 11s. That is, the second end faces 22 of the two connecting plates 20 are welded to the end face 4a of the roof cross member 4 along the slit 11s. In this way, the roof rail 3 and the roof cross member 4 are connected via the connecting plate 20. In addition, the end face 4a and a part of the upper surface of the roof cross member 4 may be welded to the outer surface and flange 15a of the inner plate 11 of the roof rail 3 via welds W4 and W5.

[0031] The upper end surface 2a of the pillar 2 is welded to the outer surface of the lower plate 14 of the roof rail 3 via a weld W6. A portion of the side surface of the pillar 2 may be welded to the flange 16a of the roof rail 3 via a weld W7.

[0032] In one embodiment, as shown in Figure 4, the frame structure 1 may include a gusset 18. The gusset 18 has a substantially triangular planar shape when viewed from the Y direction. The gusset 18 is joined to the pillar 2 and the roof cross member 4 at the upper connecting portion C1. By arranging the gusset 18 between the pillar 2 and the roof cross member 4, the rigidity of the frame structure 1 at the upper connecting portion C1 is increased.

[0033] When a load is applied to the roof rail 3 or roof cross member 4 during a vehicle rollover, stress concentrates on the roof rail 3 at the upper connection C1, potentially causing the cross-sectional shape of the roof rail 3 to collapse. In this case, the vehicle's frame structure 1 may distort, potentially leading to a loss of survival space within the vehicle. In contrast, in the frame structure 1 described above, the roof rail 3 and roof cross member 4 are connected via a connecting plate 20, thus distributing stress and improving the overall strength of the frame structure 1. In particular, with the thickness direction of the connecting plate 20 oriented in the Y direction, a portion of the connecting plate 20 is positioned within the cavity 3c of the roof rail 3, reinforcing the roof rail 3 with the rigidity of the connecting plate 20. This suppresses the collapse of the cross-section of the roof rail 3 when a load is applied to it. As a result, the joint rigidity of the pillar 2, roof rail 3, and roof cross member 4 is improved, distortion of the frame structure 1 is suppressed, and the strength and rigidity of the frame structure 1 are improved. This ensures occupant survival space and enhances the vehicle's crash safety.

[0034] Furthermore, in frame structure 1, the roof rails 3 and roof cross members 4 are connected via connecting plates 20, which allows for increased rigidity of frame structure 1 with a simple configuration. Since rigidity can be increased without adding large parts, the weight of the vehicle can be reduced. In addition, since the roof rails 3 and connecting plates 20 are welded along the first end face 21, and the roof cross members 4 and connecting plates 20 are welded along the second end face 22, the positioning of the roof rails 3 and roof cross members 4 becomes easier, and the manufacturing efficiency of frame structure 1 can be increased.

[0035] Next, the connection of the pillar 2, floor rail 5, and floor cross member 6 will be described. The pillar 2, floor rail 5, and floor cross member 6 are connected at the lower connecting section C2. Figure 8 is a perspective view showing the lower connecting section C2. Figure 9 is a cross-sectional view showing the lower connecting section C2. As shown in Figures 8 and 9, the frame structure 1 is provided with a connecting plate 30. At the lower connecting section C2, the pillar 2, floor rail 5, and floor cross member 6 are connected via the connecting plate 30. In the embodiment shown in Figure 8, the pillar 2 includes an upper pillar 2A and a lower pillar 2B.

[0036] Figure 10 is a disassembled perspective view showing the upper pillar 2A, lower pillar 2B, floor rail 5, and floor cross member 6. As shown in Figure 10, the floor rail 5 has a rectangular cross-section with a cavity 5c inside and includes an inner plate 41, an outer plate 42, an upper plate 43, and a lower plate 44. The inner plate 41 is located on the inside of the vehicle in the X direction. The outer plate 42 is located on the outside of the vehicle in the X direction and faces the inner plate 41 in the X direction. The upper plate 43 connects the upper end of the inner plate 41 and the upper end of the outer plate 42. The lower plate 44 connects the lower end of the inner plate 41 and the lower end of the outer plate 42. The upper plate 43 and the lower plate 44 face each other in the Z direction.

[0037] As shown in Figure 10, the inner plate 41 of the floor rail 5 has a slit 41s (first slit) extending in the Z direction. The outer plate 42 has a slit 42s extending in the Z direction. The length of slit 42s is shorter than the length of slit 41s. The upper plate 43 has a slit 43s (second slit) extending in the X direction. The lower plate 44 has a slit 44s (second slit) extending in the X direction. Slit 43s is connected to one end of slit 41s and one end of slit 42s. One end of slit 44s is connected to the other end of slit 41s. The other end of slit 42s and the other end of slit 44s are not connected and are spaced apart.

[0038] The upper pillar 2A has a slit 2As (fourth slit) extending in the Z direction. The slit 2As extends in the Z direction from the lower end surface 2Aa of the upper pillar 2A to an intermediate position in the longitudinal direction of the upper pillar 2A. The slit 2As may be formed on each of a pair of side walls of the upper pillar 2A that are opposite in the X direction. The lower pillar 2B has a slit 2Bs (fourth slit) extending in the Z direction. The slit 2Bs extends in the Z direction from the upper end surface 2Baa of the lower pillar 2B to an intermediate position in the longitudinal direction of the lower pillar 2B. The slit 2Bs may be formed on each of a pair of side walls of the lower pillar 2B that are opposite in the X direction.

[0039] The floor cross member 6 has a slit 6s (third slit) extending in the X direction. The slit 6s extends in the X direction from the end face 6a of the floor cross member 6 to an intermediate position on the floor cross member 6. The slit 6s may be formed on each of a pair of side walls of the floor cross member 6 that are opposite each other in the Z direction.

[0040] The connecting plate 30 is a rigid plate. The connecting plate 30 is made of a metal such as high-tensile steel, iron, or aluminum. The connecting plate 30 has a thickness that allows it to pass through the slits 2As, 2Bs, 6s, 41s, 42s, 43s, and 44s. The connecting plate 30 includes a main body 31, a first rib 32, a second rib 33, and a third rib 34. The main body 31 has a substantially rectangular shape. The first rib 32 protrudes from the main body 31 toward the inside of the vehicle in the X direction. The second rib 33 protrudes upward (Z direction) from the main body 31. The third rib 34 protrudes downward (Z direction) from the main body 31.

[0041] The connecting plate 30 is arranged along the XZ plane. The main body 31 of the connecting plate 30 is inserted into the slit 41s formed in the inner plate 41 of the floor rail 5, with the thickness direction of the connecting plate 20 facing the Y direction. As a result, the main body 31 is positioned in the cavity 5c formed within the floor rail 5. The main body 31 may also have a seating portion 35 that is inserted into the slit 42s and sits on the outer plate 42 of the floor rail 5. The seating portion 35 is supported by the floor rail 5.

[0042] As shown in Figure 11, the main body portion 31 is welded to the floor rail 5 via a welded portion W11. The welded portion W11 extends along the slits 41s, 42s, 43s, and 44s. By welding the main body portion 31 and the floor rail 5 along the slits 41s, 42s, 43s, and 44s, the connection plate 30 and the floor rail 5 are connected.

[0043] The first rib 32 protrudes inward in the vehicle width direction through the slit 41s. The first rib 32 is inserted into the slit 6s formed in the floor cross member 6. Thereby, the first rib 32 is disposed in the cavity 6c inside the floor cross member 6. As shown in Figure 8, the first rib 32 is welded to the floor cross member 6 via a welded portion W12. The welded portion W12 extends along the slit 6s. By welding the first rib 32 and the floor cross member 6 along the slit 6s, the connection plate 30 and the floor cross member 6 are connected.

[0044] The second rib 33 protrudes upward through the slit 43s formed in the upper plate 43. The second rib 33 is inserted into the slit 2As formed in the upper pillar 2A. Thereby, the second rib 33 is disposed in the cavity 2Ac of the upper pillar 2A. As shown in Figure 8, the second rib 33 is welded to the upper pillar 2A via a welded portion W13. The welded portion W13 extends along the slit 2As. By welding the second rib 33 and the upper pillar 2A along the slit 2As, the connection plate 30 and the upper pillar 2A are connected.

[0045] The third rib 34 protrudes downward through the slit 44s formed in the lower plate 44. The third rib 34 is inserted into the slit 2Bs formed in the lower pillar 2B. Thereby, the third rib 34 is disposed in the cavity 2Bc of the lower pillar 2B. As shown in Figure 8, the third rib 34 is welded to the lower pillar 2B via a welded portion W14. The welded portion W14 extends along the slit 2Bs. By welding the third rib 34 and the lower pillar 2B along the slit 2Bs, the connection plate 30 and the lower pillar 2B are connected.

[0046] As shown in Figure 9, the frame structure 1 may be provided with a gusset 48. The gusset 48 has a substantially triangular planar shape when viewed in the Y direction. The gusset 48 is joined to the upper pillar 2A and the floor cross member 6 at the lower connecting portion C2. By arranging the gusset 48 between the upper pillar 2A and the floor cross member 6, the rigidity of the frame structure 1 at the lower connecting portion C2 is enhanced.

[0047] In the frame structure 1 described above, since the upper pillar 2A, the lower pillar 2B, the floor rail 5 and the floor cross member 6 are connected via the connecting plate 30, stress is dispersed, and the strength of the lower connecting portion C2 of the frame structure 1 can be improved. In particular, since a part of the connecting plate 30 is arranged in the cavity 5c of the floor rail 5 with the thickness direction of the connecting plate 30 oriented in the Y direction, the floor rail 5 is reinforced by the rigidity of the connecting plate 30. Thereby, collapse of the cross section of the floor rail 5 when a load is applied to the floor rail 5 is suppressed. As a result, the coupling rigidity of the upper pillar 2A, the lower pillar 2B, the floor rail 5 and the floor cross member 6 is improved, distortion of the frame structure 1 is suppressed, and the strength and rigidity of the frame structure 1 are improved. Thereby, the survival space for occupants is secured, and the collision safety of the vehicle can be enhanced.

[0048] Further, in the frame structure 1, since the upper pillar 2A, the lower pillar 2B, the floor rail 5 and the floor cross member 6 are connected via the connecting plate 30, the rigidity of the frame structure 1 can be increased with a simple configuration. In addition, since the rigidity can be increased without adding large-sized components, the weight of the vehicle can be suppressed.

[0049] Furthermore, the main body portion 31 is inserted into the slits 41s, 42s, 43s, 44s of the floor rail 5, the first rib 32 is inserted into the slit 6s of the floor cross member 6, the second rib 33 is inserted into the slit 2As of the upper pillar 2A, and the third rib 34 is inserted into the slit 2Bs of the lower pillar 2B. This facilitates the positioning of the upper pillar 2A, the lower pillar 2B, the floor rail 5 and the floor cross member 6, and allows welding operations to be performed accurately, so that the manufacturing efficiency of the frame structure 1 can be improved.

[0050] Although various embodiments of the vehicle frame structure 1 have been described above, various modified forms can be constructed without being limited to the embodiments described above, and without changing the gist of the invention.

[0051] For example, in the examples shown in Figures 8 to 11, the pillar 2 includes an upper pillar 2A and a lower pillar 2B, but the lower end of the pillar 2 may be connected to the floor rail 5 and the floor cross member 6. In this case, the connecting plate 30 does not need to have a third rib 34. In this case, the second rib 33 may be inserted into a slit extending along the Z direction from the lower end surface of the pillar 2 and welded to the pillar 2 along the slit.

[0052] 1...frame structure, 2...pillar, 2A...upper pillar, 2B...lower pillar, 2As, 2Bs...slit (fourth slit), 3...roof rail (side rail), 3c...hollow, 4...roof cross member, 4a...end face, 5...floor rail (side rail), 5c...hollow, 6...floor cross member, 6s...slit (third slit), 11, 41...inner plate, 12, 42...outer plate, 13, 43...upper plate, 14, 44...lower plate, 11s...slit, 20, 30...connecting plate, 21...first end face, 22...second end face, 23...third end face, 24...fourth end face, 25...fifth end face, 31...main body, 32...first rib, 33...second rib, 34...third rib, 41s...slit (first slit), 43s...slit (second slit).

Claims

1. A vehicle frame structure comprising: a hollow pillar extending in the vertical direction of the vehicle; a hollow side rail extending in the longitudinal direction of the vehicle; a hollow cross member extending in the width direction of the vehicle; and a connecting plate, wherein the side rail includes an inner plate positioned on the inside in the width direction, an outer plate positioned on the outside in the width direction, an upper plate connecting the upper end of the inner plate and the upper end of the outer plate, and a lower plate connecting the lower end of the inner plate and the lower end of the outer plate, and has a rectangular cross section with a cavity inside; the inner plate of the side rail has a slit extending in the vertical direction; the connecting plate is inserted into the slit such that at least a part of the connecting plate is positioned in the cavity with its thickness direction oriented in the longitudinal direction; the side rail is welded to the connecting plate along the slit; the cross member is welded to the connecting plate; and the pillar is welded to the side rail or the connecting plate.

2. The frame structure for a vehicle according to claim 1, wherein the side rail is a roof rail connected to the upper end of the pillar, the cross member is a roof cross member that supports the roof panel of the vehicle, the connecting plate has a first end face extending in the width direction when viewed from the front-rear direction, and a second end face extending in the vertical direction when viewed from the front-rear direction and connected to the first end face, the first end face is welded to the lower plate within the cavity, and the second end face is exposed from the roof cross member through the slit and welded to the end face of the roof cross member.

3. The frame structure of a vehicle according to claim 2, wherein, when viewed from the front-rear direction, the connecting plate has a rectangular shape with one corner cut out, the connecting plate has a third end face extending in the vertical direction from the end of the first end face when viewed from the front-rear direction, a fourth end face extending in the width direction from the end of the second end face when viewed from the front-rear direction, and a fifth end face extending in a direction inclined with respect to the width direction between the third end face and the fourth end face when viewed from the front-rear direction, and the third end face, the fourth end face and the fifth end face are not welded to the roof rail.

4. The side rail is a floor rail connected to the pillar, the cross member is a floor cross member supporting the floor of the vehicle, the floor rail has a first slit which is the slit, and a second slit formed in at least one of the upper plate and the lower plate and extending in the width direction from the end of the first slit, the floor cross member has a third slit extending in the width direction from the end face of the floor cross member in the width direction, the pillar has a fourth slit extending in the vertical direction from the end face of the pillar in the vertical direction, the connecting plate includes a main body disposed in the cavity, a first rib protruding inward in the width direction from the main body through the first slit, and a second rib protruding in the vertical direction from the main body through the second slit, the first rib is inserted into the third slit, the second rib is inserted into the fourth slit, and the floor rail is welded to the main body along the first and second slits. The frame structure of a vehicle according to claim 1, wherein the floor cross member is welded to the first rib along the third slit, and the pillar is welded to the second rib along the fourth slit.

5. A frame structure for a vehicle according to any one of claims 1 to 4, wherein the vehicle is a bus.

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