CN107031735B

CN107031735B - Vehicle body structure

Info

Publication number: CN107031735B
Application number: CN201611207299.3A
Authority: CN
Inventors: 中村邦彦; 藤森胜哉; 有马哲宽; 滨野阳一郎
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2016-01-19
Filing date: 2016-12-23
Publication date: 2019-12-13
Anticipated expiration: 2036-12-23
Also published as: JP6218050B2; JP2017128175A; CN107031735A

Abstract

The invention provides a vehicle body structure with a sub-frame, which enables the sub-frame to easily fall off when a vehicle collides. The vehicle body structure has: a base frame (10) disposed at the center in the front-rear direction of the vehicle body; a sub-frame (30) disposed on one side of the base frame (10) in the front-rear direction of the vehicle body and below a side frame (20) extending in the front-rear direction of the vehicle body; a connecting member (50) that connects the base frame (10) and the side frames (20); and a fixing member (60) that fixes the connection member (50) and the subframe (30). A contact wall (15) that contacts the connection member (50) from below is formed on the base frame (10), an opening (15h) that opens in the vertical direction is formed in the contact wall (15), and an opposing portion (35a) that faces the contact wall (15) from below is formed at the end of the subframe (30) on the base frame (10) side. The fixing member (60) is coupled to the connecting member (50) and the facing portion (35a) through the opening (15 h).

Description

vehicle body structure

Technical Field

The present invention relates to a vehicle body structure.

Background

in the related art, there is known a vehicle body structure having a front side frame extending in a vehicle body front-rear direction at a vehicle body front portion, and a subframe disposed below the front side frame and supporting an engine, a transmission, a suspension, and the like. In the vehicle body structure, the subframe is configured to fall down when the vehicle collides in the front direction. Accordingly, the interference between the sub-frame and the power transmission system arranged in front of the sub-frame is avoided, and the influence on the carriage space is avoided.

For example, patent document 1 discloses a coupling mechanism for coupling a subframe to a mounted portion of a front side frame, the coupling mechanism including a nut provided so as to surround an opening formed in the mounted portion and a bolt screwed to the nut through the opening, and a cutout being formed in an edge of the opening in the mounted portion.

In patent document 2, a fastening base bracket for fastening a rear fastening portion of a subframe is disposed between a rear end portion of a front side frame and a front end portion of a tunnel frame, and a crack promoting hole is formed in the fastening base bracket.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 5278105

Patent document 2: japanese patent laid-open publication No. 5460684

However, in patent document 1, in order to detach the subframe with a predetermined load, it is necessary to determine the arrangement position of the notch, such as the fixing position of the nut and the positional relationship in the circumferential direction of the formation position of the top portion of the notch.

in patent document 2, it is necessary to determine the arrangement position of the crack promoting holes, such as the separation distance between the center of the fastening hole and the crack promoting holes.

therefore, in patent documents 1 and 2, the attachment structure of the subframe is complicated, and the subframe is less likely to fall off in the event of a frontal collision.

Disclosure of Invention

Therefore, an object of the present invention is to make a subframe easily come off in a vehicle body structure having the subframe when a vehicle collision occurs.

as a solution to the above problem, the invention described in claim 1 is characterized in that a vehicle body structure (for example, a vehicle body structure 1 in the embodiment) includes: a base frame (e.g., base frame 10 in the embodiment) disposed at the center in the front-rear direction of the vehicle body; a subframe (e.g., a subframe 30 in the embodiment) disposed on one side of the base frame in the vehicle body front-rear direction and disposed below a side frame (e.g., a front side frame 20 in the embodiment) extending in the vehicle body front-rear direction; a connecting member (e.g., the connecting member 50 in the embodiment) that connects the base frame and the side frame; and a fixing member (e.g., a fixing member 60 in the embodiment) that fixes the connection member and the subframe. A contact wall (e.g., a contact wall 15 in the embodiment) that contacts the connection member from below is formed on the base frame, an opening (e.g., an opening 15h in the embodiment) that opens in the vertical direction is formed on the contact wall, and an opposing portion (e.g., an opposing portion 35a in the embodiment) that faces the contact wall from below is formed at the end portion of the subframe on the base frame side. The fixing member is coupled to the coupling member and the facing portion through the opening portion.

The invention described in claim 2 is characterized in that the fixing member includes: a tubular bushing (for example, a bushing 61 in the embodiment) that is coupled to the subframe and that abuts against the connection member inside the opening portion; and a bolt (e.g., a bolt 62 in the embodiment) and a nut (e.g., a nut 63 in the embodiment) that fix the connecting member and the facing portion via the boss.

the invention described in claim 3 is characterized in that the connecting member includes: a bottom wall (e.g., bottom wall 51 in the embodiment) that abuts against the abutting wall from above; and a peripheral wall (e.g., the peripheral wall 52 in the embodiment) formed separately from the bottom wall.

The invention described in claim 4 is characterized in that the base frame has an overlapping portion (for example, an overlapping portion 17 in the embodiment) that overlaps with the peripheral wall in the thickness direction of the peripheral wall.

The invention described in claim 5 is characterized by further comprising: a tunnel cross member (e.g., tunnel cross member 6 in the embodiment) that supports a tunnel portion (e.g., tunnel portion 4a in the embodiment) at the vehicle width direction center of a floor panel (e.g., floor panel 4 in the embodiment) and has an inverted U-shape as viewed from the vehicle body front-rear direction. The peripheral wall has a connecting recess portion (e.g., connecting recess portion 55a in the embodiment) that is recessed inward in the vehicle width direction and extends along the vehicle width direction outer side portion of the tunnel cross member, and is connected to the tunnel cross member.

the invention described in claim 6 is characterized in that the peripheral wall has a ridge line portion (for example, 53a in the embodiment) which is continuous with a ridge line (for example, 20a in the embodiment) of the side frame and which is recessed inward of the peripheral wall.

The invention described in claim 7 is characterized in that the base frame has an inclined surface (for example, a front inclined surface 12a in the embodiment) which is inclined so as to be located more downward toward the center in the vehicle body longitudinal direction from an outer peripheral edge of the abutment wall (for example, a rear end 15e of the abutment wall 15 in the embodiment) as a starting point.

The invention described in claim 8 is characterized in that a vertical wall (for example, a vertical wall 19 in the embodiment) is provided in the base frame, and the vertical wall protrudes upward from a portion of the inclined surface on the side opposite to the abutment wall.

The invention described in claim 9 is characterized in that a lower arm support portion (for example, a lower arm support portion 71 in the embodiment) that supports a lower arm (for example, a lower arm 70 in the embodiment) of a suspension is provided between the sub frame and the side frame on the opposite side of the base frame of the connection member in the vehicle body front-rear direction.

The invention described in claim 10 is characterized in that the subframe includes: a first connecting portion (for example, a first connecting portion 41 in the embodiment) that is connected to an end portion of the side frame on the opposite side from the base frame in the vehicle body front-rear direction; a second connecting portion (e.g., a second connecting portion 42 in the embodiment) connected to the side frame between the first connecting portion and the facing portion; and a bent portion (e.g., a bent portion 43 in the embodiment) bent downward between the first connection portion and the second connection portion.

According to the invention described in claim 1, the base frame is provided with the abutment wall which abuts against the connection member from below, the abutment wall is provided with the opening which is opened in the vertical direction, the end portion of the subframe on the side of the base frame is provided with the facing portion which faces the abutment wall from below, and the fixing member is coupled to the connection member and the facing portion through the opening. This can provide the following effects. Hereinafter, the time when the vehicle collides in the vehicle body front-rear direction is referred to as "the time when the vehicle collides". When a load is applied downward to the opposing portion at the time of a vehicle collision, the connecting member is pressed by the contact wall (specifically, the outer peripheral portion of the opening portion). At this time, a reaction force directed upward acts on the connecting member. Therefore, stress is concentrated on the connecting member along the peripheral edge of the opening portion. Accordingly, the connecting member is cracked and broken inside the opening. Then, the breaking portion of the connecting member drops through the opening together with the fixing member. Therefore, the subframe can be easily detached when the vehicle collides.

According to the invention described in claim 2, the fixing member includes: a tubular bushing coupled to the subframe and abutting against the connection member on an inner side of the opening portion; and a bolt and a nut that fix the connecting member and the facing portion via the boss. This can provide the following effects. Since the sleeve can be sandwiched between the connection member and the facing portion, and the facing portion can be spaced apart from the opening portion, stress tends to concentrate on the connection member along the peripheral edge of the opening portion. Therefore, the connecting member can be easily broken. In addition, since the fixing member may be a bushing, a bolt, and a nut, which are common components, the fixing structure of the subframe can be simplified.

According to the invention described in claim 3, the connecting member includes: a bottom wall which abuts against the abutting wall from above; and a peripheral wall formed separately from the bottom wall. This can provide the following effects. Since the bottom wall and the peripheral wall can be formed of different materials and thicknesses from each other, the degree of freedom of design corresponding to the required specifications can be improved. For example, the bottom wall may be formed of a material having low strength, in order to facilitate the breakage of the connection member. On the other hand, the thickness of the bottom wall can be increased from the viewpoint of improving the support rigidity of the subframe.

According to the invention described in claim 4, the base frame has an overlapping portion that overlaps the peripheral wall in the thickness direction of the peripheral wall. Accordingly, since the rigidity can be ensured by the overlapping portion, the thickness of the peripheral wall can be reduced, and the weight can be reduced.

according to the invention recited in claim 5, the peripheral wall has a connecting recessed portion that is recessed inward in the vehicle width direction, extends along an outer side portion of the tunnel cross member in the vehicle width direction, and is connected to the tunnel cross member. This can provide the following effects. Since the load applied from the subframe can be received by the tunnel cross member via the connecting recess, the rigidity of the periphery of the subframe mounting portion (e.g., the facing portion, the connecting member, and the like) can be improved.

according to the invention described in claim 6, the peripheral wall has the ridge line portion that is continuous with the ridge line of the side frame and that is recessed inward of the peripheral wall. This can provide the following effects. When a vehicle collision occurs (including an offset collision), a load applied from the side frame can be transmitted from the ridge line of the side frame to the base frame via the ridge line portion of the peripheral wall.

According to the invention described in claim 7, the base frame has the inclined surface that is inclined so as to be located more downward toward the center in the front-rear direction of the vehicle body, with the outer peripheral edge of the abutment wall as a starting point. This can provide the following effects. When a vehicle collision occurs, the opposing portion can be brought into contact with the inclined surface and can be slid downward along the inclined surface, so that a downward load can be easily applied to the opposing portion. Therefore, the connecting member can be easily broken.

according to the invention described in claim 8, the base frame is provided with a vertical wall that protrudes upward from a portion of the inclined surface on the side opposite to the abutment wall. This can provide the following effects. When a vehicle collision occurs, the opposing portions can slide downward along the inclined surfaces, and then the subframe can be rotated downward using the lower end of the vertical wall as a fulcrum according to the "lever principle". Therefore, the downward load can be efficiently generated in the fixing member. Therefore, the breakage of the connection member can be facilitated.

According to the invention recited in claim 9, a lower arm support portion that supports a lower arm of a suspension is provided between the sub frame and the side frame on the side opposite to the base frame of the connection member in the vehicle body front-rear direction. This can provide the following effects. The degree of freedom in design of the lower arm can be increased, and the connecting member can be disposed at one end of the base frame in the front-rear direction of the vehicle body.

According to the invention described in claim 10, the subframe includes: a first connecting portion connected to an end portion of the side frame opposite to the base frame in a vehicle body front-rear direction; a second connecting portion connected to the side frame between the first connecting portion and the facing portion; and a bent portion bent downward between the first connection portion and the second connection portion. This can provide the following effects. In the vehicle collision, the subframe is bent downward with the bent portion as a starting point, and therefore, the subframe can be rotated downward with the bent portion as a fulcrum according to the "lever principle". Therefore, the downward load can be efficiently generated in the fixing member. Therefore, the connecting member can be more easily broken.

Drawings

fig. 1 is a perspective view of a vehicle body structure according to an embodiment of the present invention, as viewed obliquely from below.

Fig. 2 is a perspective view showing a peripheral structure of the tunnel cross member as viewed obliquely from below in a state where the subframe is removed.

Fig. 3 is a sectional perspective view of the connection structure of the subframe and the connection member as viewed obliquely from below.

Fig. 4 is a bottom view showing a connection structure of the base frame and the connection member.

Fig. 5 is a side view showing a connection structure of the subframe and the front side frame.

Fig. 6 is a bottom view showing the lower arm support portion.

Fig. 7 is a view for explaining the subframe falling due to the action of the opening portion in the base frame.

Fig. 8 is a view for explaining the subframe falling, which follows fig. 7.

Fig. 9 is a diagram for explaining breakage of the connection member due to the action of the front inclined surface and the vertical wall in the base frame.

Description of the reference numerals

1: a vehicle body structure; 4: a base plate; 4 a: a channel portion; 6: a channel beam; 6 a: a vehicle width direction outer side portion of the tunnel cross member; 10: a base frame; 12 a: a front inclined surface (inclined surface); 15: an abutment wall; 15 e: the rear end of the abutment wall (the outer periphery of the abutment wall); 15 h: an opening part; 17: an overlapping portion; 19: a longitudinal wall; 20: a front side frame (side frame); 20 a: a ridge line; 30: an auxiliary frame; 35 a: an opposing portion; 41: a first connection portion; 42: a second connecting portion; 43: a bending section; 50: a connecting member; 51: a bottom wall; 52: a peripheral wall; 53 a: a ridge line portion; 55 a: a connecting recess; 60: a fixing member; 61: a shaft sleeve; 62: a bolt; 63: a nut; 70: a lower arm; 71: the lower arm support portion.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment of the present invention, an example in which a vehicle body structure is applied to the front portion side of a vehicle will be described. Unless otherwise specified, the directions such as front, rear, left, and right in the following description are the same as the directions of the vehicle to which the present invention is applied. In the drawings used in the following description, arrow FR indicating the front of the vehicle, arrow LH indicating the left of the vehicle, and arrow UP indicating the upper side of the vehicle are shown at appropriate positions.

< vehicle body Structure >

Fig. 1 is a perspective view of a vehicle body structure 1 viewed obliquely from below. In fig. 1, a framework of a vehicle front portion in a vehicle body structure 1 is mainly shown.

as shown in fig. 1, a vehicle body structure 1 includes: a base frame 10 disposed at the center in the front-rear direction of the vehicle body; a pair of left and right front side frames 20 (side frames) that are positioned in front of the vehicle, disposed on both sides in the vehicle width direction, and extend in the vehicle body front-rear direction; a subframe 30 disposed on the front side of the base frame 10 and below the front side frame 20; a connecting member 50 connecting the base frame 10 and the front side frame 20; and a fixing member 60 fixing the connecting member 50 and the subframe 30.

referring to fig. 1 and 2 together, the vehicle body structure 1 further has: a dashboard lower member 5 that partitions the vehicle compartment 2 and the engine room 3 in front of the vehicle compartment; and a tunnel cross member 6 that supports a tunnel portion 4a facing the center in the vehicle width direction of the floor 4 in the vehicle compartment 2 and has an inverted U-shape as viewed from the front-rear direction of the vehicle body.

in the drawings, reference numeral 7 denotes a reinforcement member 7, and the reinforcement member 7 extends in the vehicle width direction and has a flange portion joined to a front lower portion of the dash lower member 5.

< basic frame >

As shown in fig. 1, the base frame 10 has: a pair of left and right floor frames 11 disposed on the rear side of the front side frame 20 and on both sides in the vehicle width direction, and extending in the vehicle body front-rear direction; a pair of left and right center frames 12 disposed between the left and right floor frames 11 in the vehicle width direction and extending in the vehicle body front-rear direction; the pair of left and right side members 13 are disposed further to the outside in the vehicle width direction (specifically, the vehicle width direction outer ends of the base frame 10) than the left and right floor frames 11, and extend in the vehicle body front-rear direction.

The floor frame 11 and the center frame 12 have U-shaped cross sections that open upward. The side member 13 has a U-shaped cross section that opens inward in the vehicle width direction. Flange portions 11f, 12f joined to the lower surfaces of the floor panel 4 and the dashboard lower 5 are formed respectively on the open cross-sectional upper portions of the floor frame 11 and the center frame 12. Accordingly, the floor frame 11 and the center frame 12 constitute a continuous closed cross section extending in the vehicle body front-rear direction.

Referring to fig. 3 and 4 together, the center frame 12 has formed at its front end portion: an abutting wall 15 abutting against the connecting member 50 from below; and a side wall 16 that is connected to the abutment wall 15 and abuts against the link member 50 from the front and the inside in the vehicle width direction. The abutting wall 15 has a thickness in the up-down direction, and has a shape extending substantially in the horizontal direction.

An opening 15h that opens in the vertical direction is formed in the contact wall 15. In the plan view of fig. 4, the opening 15h is located at the center in the front-rear direction and the center in the vehicle width direction of the abutment wall 15. In the plan view of fig. 4, the opening 15h has a circular shape larger than the outer diameter of the seat portion 63b of the nut 63 in the fixing member 60.

as shown in fig. 3, the center frame 12 includes: a front inclined surface 12a that is inclined so as to be located more downward toward the center (i.e., more rearward) in the vehicle body front-rear direction, with an outer peripheral edge (i.e., a rear end 15e) of the abutment wall 15 as a starting point; a horizontal surface 12b connected to the front inclined surface 12a and extending substantially horizontally in the front-rear direction of the vehicle body; and a rear inclined surface 12c that is connected to the horizontal surface 12b and extends obliquely upward and rearward. Here, the front inclined surface 12a corresponds to an "inclined surface" described in claims. The front inclined surface 12a is continuous with the rear end 15e of the abutment wall 15, and extends gently obliquely from the rear end 15e of the abutment wall 15 to the front end of the horizontal surface 12b so as to be located lower toward the rear side.

as shown in fig. 4, the center frame 12 has an overlapping portion 17, and the overlapping portion 17 overlaps the peripheral wall 52 of the connecting member 50 in the thickness direction of the peripheral wall 52. The overlapping portion 17 has: an inner overlapping portion 17a that is continuous with a front end of a flange portion 12f of the center frame 12 on the vehicle width direction inner side and extends along an outer surface of an inner wall portion 55 of the peripheral wall 52; and an outer overlapping portion 17b that is continuous with a front end of the flange portion 12f of the center frame 12 on the vehicle width direction outer side and extends along an outer surface of the rear wall portion 54 on the peripheral wall 52.

As shown in fig. 3, a reinforcement plate 18 is connected to the center frame 12, and the reinforcement plate 18 extends along the front inclined surface 12a, the horizontal surface 12b, and the rear inclined surface 12c, and has a plate shape along the inner peripheral wall surface of the center frame 12. The front end of the reinforcement plate 18 is apart rearward and downward from the rear end 15e of the abutment wall 15. Specifically, the front end of the reinforcement plate 18 is positioned slightly forward of the front-rear middle portion of the front inclined surface 12a and slightly above the vertical middle portion of the front inclined surface 12 a.

The center frame 12 is provided with a vertical wall 19, and the vertical wall 19 protrudes upward from a portion of the front inclined surface 12a opposite to the abutment wall 15 (i.e., a portion on the rear side of the front inclined surface 12 a). The vertical wall 19 is disposed above the front-rear middle portion of the horizontal surface 12b on the center frame 12. In the sectional view of fig. 3, the vertical wall 19 is L-shaped. The vertical wall 19 has: a lower wall portion 19a that abuts against a lower wall of the reinforcing plate 18 (i.e., a portion of the reinforcing plate 18 that overlaps the horizontal surface 12b in the vertical direction) from above and is coupled to the reinforcing plate 18; and a rising wall portion 19b that is continuous with the lower wall portion 19a and rises upward from the front end of the lower wall portion 19 a.

< front side frame >

In the side view of fig. 5, the front side frame 20 has: a front side frame body 21 extending substantially horizontally from the front to the rear of the vehicle; and a front side frame rear end portion 22 that is connected to the front side frame main body 21 and extends obliquely so as to be located lower toward the rear side from the rear end of the front side frame main body 21 toward the front end portion of the base frame 10.

Referring to fig. 1 and 2 together, both side portions in the vehicle width direction of a dash panel for supporting a radiator, not shown, are attached to the front end portions of the left and right front side frame bodies 21. The front side frame body 21 has a closed cross-sectional structure having a rectangular cross section. The front frame rear end portion 22 has a U-shaped cross section that opens upward. A flange portion 22f joined to the bottom plate 4 and the lower surface of the dash lower member 5 is formed at the upper portion of the open cross section of the front side frame rear end portion 22. Accordingly, the front side frame rear end portion 22 forms a closed cross section that is continuous in the vehicle body front-rear direction.

The rear end of the front side frame rear end 22 extends rearward and is coupled to the front end of the floor frame 11. Further, the vehicle width direction outer side portion of the front side frame rear end portion 22 is connected to the front end portion of the side member 13 via an outrigger 23 which is a frame member having a U-shaped cross section that opens upward. A through hole 22h that is opened in the vertical direction and is circular in plan view is formed in the lower end portion of the front-rear intermediate portion of the front-side frame rear end portion 22.

< subframe >

As shown in FIG. 1, the subframe 30 is in the form of a well. The subframe 30 includes: a subframe main body 31 having a flat shape extending in the vehicle width direction; a pair of left and right side members 32 disposed on both sides in the vehicle width direction and extending forward in an expanded shape from the front end of the subframe main body 31 and both side portions in the vehicle width direction; a front cross member 33 extending in the vehicle width direction so as to straddle between front portions of the left and right side members 32; and a pair of left and right tie braces 34 that are disposed on both sides in the vehicle width direction and protrude rearward from both side portions in the vehicle width direction of the subframe main body 31.

For example, the subframe body 31 is cast from an aluminum alloy or the like. A long hole 31h that opens in the vertical direction and extends in the vehicle width direction is formed in the vehicle width direction center at the rear portion of the subframe main body 31. As shown in fig. 6, a plurality of reinforcing ribs 31a are formed on the subframe main body 31. This can improve the weight reduction and rigidity of the subframe main body 31.

As shown in fig. 1, the left and right side members 32 are press-formed of light alloy, steel, or the like. The left and right side members 32 extend gently obliquely in the vehicle longitudinal direction so as to be positioned further inward in the vehicle width direction toward the rear side in the vehicle longitudinal direction.

The front cross member 33 is formed in a gentle U shape that opens rearward (i.e., is convex forward) and extends in the vehicle width direction. Both ends of the front cross member 33 in the vehicle width direction are joined to front lower surfaces of the left and right side frames 32.

The left and right joint supports 34 are located at the end portions (i.e., rear end portions) of the subframe 30 on the base frame 10 side. As shown in fig. 3, the left and right link supports 34 are formed with facing portions 35a that face the abutment walls 15 of the center frame 12 from below.

Referring to fig. 1 and 3 together, the joint supporter 34 has a hollow structure extending in the front-rear direction of the vehicle body. The connection support 34 has: top plates 35 connected to upper ends of both vehicle-width-direction side portions of the subframe main body 31 and extending in the vehicle body front-rear direction; a bottom plate portion 36 that is continuous with the lower ends of both vehicle-width-direction side portions of the subframe main body 31, is spaced downward from the top plate portion 35, and extends in the vehicle body front-rear direction; and a side plate portion 37 extending in the vehicle body front-rear direction and the vertical direction so as to be continuous with the outer peripheral edges of the top plate portion 35 and the bottom plate portion 36.

The top plate 35 is spaced downward from the lower surface of the center frame 12. The ceiling portion 35 extends with a gentle inclination in the vehicle body longitudinal direction so as to extend along the abutment wall 15, the front inclined surface 12a, and the horizontal surface 12b of the center frame 12. A curved wall portion 35b is formed at the rear end portion of the top plate portion 35, and the curved wall portion 35b is curved and extended rearward and downward at a position overlapping with the front-rear intermediate portion of the horizontal surface 12b in the vertical direction, and then is curved downward.

The top plate 35 is formed with an upper insertion hole 35h, and the upper insertion hole 35h is vertically opened at a position overlapping the opening 15h of the contact wall 15. In plan view, the upper insertion hole 35h has a circular shape smaller than the inner diameter of the opening 15h of the contact wall 15 and larger than the insertion hole 51h of the connection member 50.

The bottom plate portion 36 extends in the vehicle body longitudinal direction below the top plate portion 35. The vertical separation distance between the top plate 35 and the bottom plate 36 gradually decreases toward the rear side. A protruding wall portion 36a is formed at the rear end portion of the bottom plate portion 36, and the protruding wall portion 36a protrudes upward at a position overlapping the curved wall portion 35b of the top plate portion 35 and forward of the curved wall portion 35b in the vertical direction.

The bottom plate portion 36 is formed with a lower insertion hole 36h, and the lower insertion hole 36h is opened in the vertical direction at a position overlapping the upper insertion hole 35h of the top plate portion 35 in the vertical direction. In a plan view, the lower insertion hole 36h has a circular shape smaller than the inner diameter of the upper insertion hole 35h and larger than the insertion hole 51h of the connection member 50. The bottom plate portion 36 has a through hole 36j that is opened in the vertical direction and is circular in plan view, formed in front of the lower insertion hole 36 h.

A cylindrical connection boss 38 is connected to a front-rear intermediate portion of the connection support 34, and the connection boss 38 extends vertically so as to connect the top plate portion 35 and the bottom plate portion 36 vertically. A plurality of (for example, 2 in the present embodiment) connection bosses 38 are provided at intervals in the vehicle body longitudinal direction so as to be arranged in the front-rear direction with a through hole 36j interposed therebetween.

A reinforcing member 39 is connected to the rear end portion of the joint stay 34, and the reinforcing member 39 extends along the top plate portion 35, the bottom plate portion 36, and the protruding wall portion 36a, and has a plate shape along the inner circumferential wall surface of the joint stay 34. In the sectional view of fig. 3, the reinforcing member 39 has a U-shaped cross section that opens forward. This can improve the rigidity of the joint supporter 34.

Referring to fig. 3 and 6 together, a connecting plate 40 is provided at the vehicle width direction outer side portion of the link stay 34, and the connecting plate 40 extends in the front-rear direction along the vehicle width direction outer side surface of the link stay 34, and has an L-shaped cross section that opens upward and inward in the vehicle width direction. An upper flange portion 40f is formed at an upper portion of the open cross section of the connecting plate 40, and the upper flange portion 40f is joined to the front end portion of the center frame 12 and the lower surface of the connecting member 50. A lower flange portion 40g is formed at the vehicle width direction inner side end of the open cross section of the connecting plate 40, and this lower flange portion 40g is joined to the lower end portion of the vehicle width direction outer side portion of the connecting stay 34.

as shown in fig. 5, the subframe 30 further includes: a first connecting portion 41 connected to an end portion (i.e., a front end portion) of the front side frame 20 on the opposite side from the base frame 10 in the vehicle body front-rear direction; a second connecting portion 42 connected to the front side frame 20 between the first connecting portion 41 and the facing portion 35 a; and a bent portion 43 bent downward between the first connection portion 41 and the second connection portion 42.

The first connecting portion 41 projects upward from the front end portion of the side member 32 and is attached to a lower portion of the front end portion of the front side frame body 21. The first connecting portion 41 extends vertically so as to connect between the front end portion of the side member 32 and the front end portion of the front side frame body 21, and is formed in a tubular shape having a rectangular cross section.

The second connecting portion 42 is attached to the rear end portion of the front side frame body 21 (specifically, the lower portion of the bulging portion 21a bulging downward from the rear end portion of the front side frame body 21) so as to project upward and outward in the vehicle width direction from the front portion and the vehicle width direction side portion of the subframe body 31. The second connection portion 42 is configured to: when a vehicle collision occurs, it separates from the left and right front side frames 20 earlier than the first connecting portion 41.

The second connection portion 42 has: an arm portion 42a that protrudes and extends upward and outward in the vehicle width direction from the subframe main body 31; and a connecting bracket 42b that connects the upper end portion of the arm portion 42a and the bulging portion 21a of the front side frame main body 21. The upper end of the arm portion 42a is fixed to the connecting bracket 42b by a plurality of (for example, 2 in the present embodiment) bolts 42c aligned in the front-rear direction.

The connection bracket 42b is formed with a hole (not shown) for inserting the bolt 42c and a notch 42h for opening a part of the hole downward. Therefore, when the arm portion 42a receives a load that is pulled downward at the time of a vehicle collision, the arm portion 42a and the bolt 42c break the notch portion 42h in a state where the connecting bracket 42b is retained on the front side frame 20 side. The arm portion 42a is separated downward from the connecting bracket 42b, and is allowed to be displaced downward of the subframe 30.

In the side view of fig. 5, the bent portion 43 is bent to be convex downward at the front-rear middle portion of the side member 32. The upper surface of the side member 32 extends gently obliquely in the vehicle body longitudinal direction so as to be located more downward toward the bent portion 43 side. The bent portion 43 is not bent at all in general, but when a collision load in the front-rear direction equal to or greater than a predetermined value is applied to the vehicle, the side member 32 serves as a starting point at which the front-rear intermediate portion is bent downward.

In the drawings, reference numeral 25 denotes a wheel house member, reference numeral 26 denotes a front wheel house, and reference numeral 27 denotes a front inner lower pillar.

< connecting part >

As shown in fig. 3 and 4, the connecting member 50 includes: a bottom wall 51 that abuts the abutment wall 15 of the center frame 12 from above; and a peripheral wall 52 formed separately from the bottom wall 51.

The bottom wall 51 has a thickness in the vertical direction and has a shape extending in the vehicle width direction. A front flange 51f is formed at the front end of the bottom wall 51, and the front flange 51f rises upward from the front end of the bottom wall 51 and is joined to the lower end of the front wall 53 of the peripheral wall 52. A rear flange 51g is formed at the rear end portion of the bottom wall 51, and the rear flange 51g extends obliquely rearward and upward from the rear end of the bottom wall 51 and is joined to the lower end portion of the rear wall portion 54 in the peripheral wall 52.

The bottom wall 51 is formed with insertion holes 51h, which are opened in the vertical direction and through which the bolts 62 of the fixing member 60 are inserted, and the insertion holes 51 h. In the bottom view of fig. 4, the insertion hole 51h is located at the center in the front-rear direction and the center in the vehicle width direction of the bottom wall 51. In the bottom view of fig. 4, the insertion hole 51h is formed in a circular shape slightly larger than the outer diameter of the shaft portion 62a (see fig. 3) of the bolt 62 and smaller than the inner diameter of the opening 15 h.

The peripheral wall 52 has a shape rising upward from the outer peripheral edge of the bottom wall 51 and opening upward and outward in the vehicle width direction. The peripheral wall 52 has: a front wall portion 53 extending in the vertical direction; a rear wall portion 54 that extends obliquely in the vehicle body longitudinal direction so as to be located further upward toward the rear side at a position that is rearward away from the front wall portion 53; and an inner wall portion 55 extending vertically so as to connect the vehicle width direction inner end of the front wall portion 53 and the vehicle width direction inner end of the rear wall portion 54 between the front and rear.

Referring to fig. 2 and 4 together, a front flange portion 53f is formed on the outer periphery of the front wall portion 53 of the peripheral wall 52, and this front flange portion 53f extends while being bent outward of the peripheral wall 52 and is joined to the lower surfaces of the floor panel 4 and the dash lower member 5 and the vehicle width direction inner side surface of the front side frame rear end portion 22. A rear flange portion 54f is formed on the outer periphery of the rear wall portion 54 of the peripheral wall 52, and this rear flange portion 54f extends in a curved manner to the outside of the peripheral wall 52 and is joined to the lower surfaces of the floor panel 4 and the dash lower member 5 and the vehicle width direction inner side surface of the front side frame rear end portion 22.

The peripheral wall 52 further has: a connecting recessed portion 55a that is connected to the tunnel cross member 6 so as to be recessed inward in the vehicle width direction and extend along the vehicle width direction outer side portion of the tunnel cross member 6; and a ridge line portion 53a that is continuous with the ridge line 20a of the front side frame 20 and is recessed inward of the peripheral wall 52.

The connection recess 55a is formed in the peripheral wall 52 at a front-rear intermediate portion of the inner wall portion 55. The connecting recess 55a is recessed inward in the vehicle width direction along the vehicle width direction outer side portion 6a of the tunnel cross member 6, and extends obliquely in the vertical direction so as to be located inward in the vehicle width direction as it goes upward.

The ridge line portion 53a is formed at the lower and vehicle width direction outer side portion of the front wall portion 53 on the peripheral wall 52. The ridge line portion 53a extends at a gentle slope in the vehicle width direction from the ridge line 20a of the front side frame 20 toward the front end of the center frame 12 via the vehicle width direction outer side portion of the front flange portion 53 f.

< fixing part >

As shown in fig. 3, the fixing member 60 is inserted through the opening 15h of the contact wall 15 in the center frame 12 and coupled to the connecting member 50 and the facing portion 35 a. The fixing member 60 includes: a cylindrical boss 61 coupled to the sub-frame 30 and abutting against the connection member 50 on the inner side of the opening 15 h; and a bolt 62 and a nut 63 that fix the connecting member 50 and the facing portion 35a via the boss 61. In fig. 3, for convenience of explanation, the bolt 62 is removed from the nut 63 and is separated from the lower portion of the lower insertion hole 36 h.

The sleeve 61 has: a cylindrical tube portion 61a extending vertically; and an enlarged diameter portion 61b that is enlarged in diameter from the upper end of the cylindrical portion 61a to the outside in the radial direction. The lower end of the tube portion 61a is coupled to the outer peripheral portion of the lower insertion hole 36h in the bottom plate portion 36 of the subframe 30. The outer peripheral surface of the enlarged diameter portion 61b is joined to the inner peripheral edge of the upper insertion hole 35h in the top plate portion 35 of the subframe 30. The upper end of the enlarged diameter portion 61b passes through the opening 15h of the abutment wall 15 in the center frame 12 and is coupled to or in abutment with the lower surface of the bottom wall 51 in the connection member 50.

the bolt 62 has: a shaft portion 62a having a male screw portion 62c screwed to the female screw portion 63c of the nut 63 and extending vertically; and a head portion 62b coupled to a lower end of the shaft portion 62 a.

The shaft portion 62a has an outer diameter slightly smaller than the inner diameter of the insertion hole 51h in the bottom wall 51 of the connection member 50, as viewed in a direction extending along the axis C1 of the boss 61 (i.e., in plan view). The head portion 62b has an outer diameter larger than the inner diameter of the lower insertion hole 36h in the bottom plate portion 36 of the subframe 30 as viewed in the direction along the axis C1 (i.e., in the bottom view of fig. 6).

the nut 63 has: a cylindrical portion 63a having an internal thread portion 63c and having a cylindrical shape extending vertically; and a seat portion 63b that expands radially outward from a lower end of the cylindrical portion 63 a. The nut 63 is, for example, a weld nut.

The cylindrical portion 63a has an inner diameter slightly smaller than the inner diameter of the insertion hole 51h in the bottom wall 51 of the connection member 50 as viewed in the direction along the axis C1. The seat portion 63b is formed in a circular shape having an outer diameter larger than the inner diameter of the insertion hole 51h in the bottom wall 51 of the link member 50 and smaller than the inner diameter of the opening portion 15h of the abutment wall 15 in the center frame 12, as viewed in the direction along the axis C1 (i.e., in the bottom view of fig. 4). The seat 63b is vertically coupled to the upper surface of the bottom wall 51 at a position overlapping the outer periphery of the insertion hole 51h in the bottom wall 51 of the connection member 50.

< lower arm support >

As shown in fig. 6, a lower arm support portion 71 that supports a lower arm 70 of the suspension is provided between the subframe 30 and the front side frame 20 on the opposite side of the connecting member 50 from the base frame 10 (i.e., on the front side of the connecting member 50) in the vehicle body front-rear direction. In the bottom view of fig. 6, the lower arm 70 has: a lower arm body 70a extending in the vehicle width direction and having a Y shape that opens inward in the vehicle width direction; and a cylindrical supported boss portion 70b that protrudes rearward from a rear end portion of the lower arm main body 70a on the vehicle width direction inner side. In fig. 6, reference numeral 75 denotes a front wheel on the left side of the vehicle.

The lower arm support portion 71 includes: a lower arm support portion main body 71a disposed between the connection stay 34 of the subframe 30 and the front side frame rear end portion 22 in the vehicle width direction in front of the connection member 50; an inner bracket 71b that protrudes inward in the vehicle width direction from the lower arm support portion main body 71a and is connected to the linking stay 34; and an outer bracket 71c that protrudes outward in the vehicle width direction from the lower arm support portion main body 71a and is connected to a lower end portion of a front-rear intermediate portion of the front side frame rear end portion 22.

Referring to fig. 3 and 6, the inner bracket 71b is coupled to the upper end of the connection boss 38 projecting upward from the top plate 35 of the connection support 34, and is fastened to the bottom plate 36 of the connection support 34 by a bolt 72 and a nut not shown through the through hole 36j of the bottom plate 36 of the connection support 34. Referring to fig. 2 and 6 together, the outer bracket 71c is fastened to the lower end portion of the front-rear intermediate portion of the front-side frame rear end portion 22 by bolts 73 and nuts not shown through the through holes 22h of the lower end portion of the front-rear intermediate portion of the front-side frame rear end portion 22.

< Effect of opening in base frame >

Next, an example in which the subframe 30 falls down due to the action of the opening portion 15h in the base frame 10 will be described.

As shown in fig. 7, when a load is applied downward (in the direction of arrow V1) to the opposing portion 35a of the subframe 30 during a vehicle collision, the bottom wall 51 of the connecting member 50 is pressed against the contact wall 15 of the center frame 12 (specifically, the outer peripheral portion of the opening portion 15 h). At this time, a reaction force directed upward (arrow V2) acts on the bottom wall 51 of the connecting member 50. Therefore, stress is concentrated on the bottom wall 51 of the connecting member 50 along the peripheral edge of the opening 15 h.

Accordingly, bottom wall 51 of connecting member 50 is cracked and broken inside opening 15 h. Thus, as shown in fig. 8, the broken portion of the bottom wall 51 of the connecting member 50 passes through the opening 15h and drops together with the fixing member 60. In fig. 7 and 8, a portion of the bottom wall 51 that overlaps the peripheral edge of the opening 15h in the vertical direction is indicated by a broken line.

< Effect of inclined surface and vertical wall in base frame >

Next, an example in which the connecting member 50 is broken by the action of the front inclined surface 12a and the vertical wall 19 in the base frame 10 will be described.

As shown in fig. 3, when a load is applied to the subframe 30 in the rearward direction at the time of a vehicle collision, the opposing portion 35a of the subframe 30 contacts the front inclined surface 12a of the base frame 10. Thus, the opposing portion 35a of the subframe 30 slides downward along the front inclined surface 12 a. When the opposing portion 35a slides downward along the front inclined surface 12a, it abuts against the lower end of the vertical wall 19.

Thus, as shown in fig. 9, the subframe 30 rotates downward, specifically, counterclockwise (in the direction of arrow V3) about the fulcrum P1, according to the "lever principle" with the lower end of the vertical wall 19 as the fulcrum P1. Therefore, a downward load is effectively applied to the fixing member 60, and the bottom wall 51 of the connecting member 50 is cracked and broken inside the opening 15 h. Thus, the broken portion of the bottom wall 51 of the connecting member 50 passes through the opening 15h and drops together with the fixing member 60. In fig. 9, for convenience of explanation, the position of the nut 63 before the bottom wall 51 is broken (i.e., in a normal state) is indicated by a broken line.

As described above, the vehicle body structure 1 according to the above embodiment includes: a base frame 10 disposed at the center in the front-rear direction of the vehicle body; a subframe 30 disposed on one side of the base frame 10 in the vehicle body front-rear direction and disposed below the front side frame 20 extending in the vehicle body front-rear direction; a connecting member 50 connecting the base frame 10 and the front side frame 20; and a fixing member 60 fixing the connecting member 50 and the subframe 30. The base frame 10 is provided with an abutment wall 15 that abuts against the connection member 50 from below, the abutment wall 15 is provided with an opening 15h that opens in the vertical direction, and an opposing portion 35a that faces the abutment wall 15 from below is provided at an end of the subframe 30 on the base frame 10 side. The fixing member 60 is coupled to the coupling member 50 and the facing portion 35a through the opening 15 h.

According to this structure, when a downward load is applied to the opposing portion 35a during a vehicle collision, the connecting member 50 is pressed by the contact wall 15 (specifically, the outer peripheral portion of the opening portion 15 h). At this time, a reaction force directed upward acts on the connecting member 50. Therefore, stress concentrates on the connection member 50 along the peripheral edge of the opening portion 15 h. Accordingly, the connecting member 50 is cracked and broken inside the opening 15 h. Then, the breaking portion of the connecting member 50 passes through the opening 15h and drops together with the fixing member 60. Therefore, the subframe 30 can be easily detached when the vehicle collides. Further, the deformation stroke of the front side frame 20 can be increased to absorb the collision energy.

In the above embodiment, the fixing member 60 includes: a tubular boss 61 coupled to the sub-frame 30 and abutting against the connection member 50 on the inner side of the opening 15 h; and a bolt 62 and a nut 63 that fix the connecting member 50 and the facing portion 35a via the boss 61. This can provide the following effects. Since the boss 61 can be sandwiched between the connection member 50 and the facing portion 35a can be separated from the opening 15h, stress can be easily concentrated on the connection member 50 along the peripheral edge of the opening 15. Thereby enabling the connection member 50 to be easily broken. Further, since the fixing member 60 can employ the boss 61, the bolt 62, and the nut 63 as common components, the fixing structure of the subframe 30 can be simplified.

In the above embodiment, the connecting member 50 includes: a bottom wall 51 that abuts against the abutting wall 15 from above; and a peripheral wall 52 formed separately from the bottom wall 51. This can provide the following effects. Since the bottom wall 51 and the peripheral wall 52 can be formed of different materials and thicknesses from each other, the degree of freedom of design corresponding to the required specifications can be improved. For example, the bottom wall 51 may be formed of a material having low strength, from the viewpoint that the connecting member 50 is easily broken. On the other hand, the thickness of the bottom wall 51 can be increased from the viewpoint of improving the support rigidity of the subframe 30.

In the above embodiment, the peripheral wall 52 has the overlapping portion 17, and the overlapping portion 17 overlaps the base frame 10 in the thickness direction of the peripheral wall 52. Accordingly, since the rigidity can be ensured by the overlapping portion 17, the thickness of the peripheral wall 52 can be reduced, and weight reduction can be achieved.

In the above embodiment, the peripheral wall 52 has the connecting recess 55a, and the connecting recess 55a is recessed inward in the vehicle width direction, extends along the vehicle width direction outer side portion of the tunnel cross member 6, and is connected to the tunnel cross member 6. This can provide the following effects. Since the load applied from the subframe 30 can be received by the tunnel cross member 6 via the connection recess 55a, the rigidity of the periphery of the subframe 30 mounting portion (e.g., the facing portion 35a and the connection member 50) can be improved.

in the above embodiment, the peripheral wall 52 has the ridge line portion 53a, and the ridge line portion 53a is continuous with the ridge line 20a of the front side frame 20 and is recessed inward of the peripheral wall 52. This can provide the following effects. When a vehicle collision occurs (including an offset collision), the load applied from the front side frame 20 can be transmitted from the ridge line 20a of the front side frame 20 to the base frame 10 via the ridge line portion 53a of the peripheral wall 52. In the present embodiment, since the base frame 10 includes the floor frames 11 and the center frame 12 arranged in plural in the vehicle width direction, the load applied can be dispersed and transmitted to the floor frames 11 and the center frame 12.

In the above embodiment, the base frame 10 has the front inclined surface 12a, and the front inclined surface 12a is inclined so as to be located more downward toward the center in the vehicle body front-rear direction with the outer peripheral edge of the contact wall 15 as a starting point. This can provide the following effects. When a vehicle collision occurs, since the opposing portion 35a can be brought into contact with the front inclined surface 12a and can be slid downward along the front inclined surface 12a, a downward load can be easily applied to the opposing portion 35 a. Therefore, the connecting member 50 can be easily broken.

In the above embodiment, the base frame 10 is provided with the vertical wall 19, and the vertical wall 19 protrudes upward from the portion of the front inclined surface 12a opposite to the abutment wall 15. This can provide the following effects. When a vehicle collision occurs, the opposing portion 35a can slide downward along the front inclined surface 12a, and then the subframe 30 can be rotated downward by the "lever principle" using the lower end of the vertical wall 19 as a fulcrum P1. Therefore, the downward load can be efficiently generated in the fixing member 60. Therefore, the connection member 50 can be more easily broken.

In the above embodiment, the lower arm support portion 71 that supports the lower arm 70 of the suspension is provided between the sub frame 30 and the front side frame 20 on the side opposite to the base frame 10 of the connection member 50 in the vehicle body front-rear direction. This can provide the following effects. The connecting member 50 can be disposed at one end of the base frame 10 in the front-rear direction of the vehicle body while increasing the degree of freedom in designing the lower arm 70.

In the above embodiment, the subframe 30 includes: a first connecting portion 41 connected to an end portion of the front side frame 20 opposite to the base frame 10 in the vehicle body front-rear direction; a second connecting portion 42 connected to the front side frame 20 between the first connecting portion 41 and the facing portion 35 a; and a bent portion 43 bent downward between the first connection portion 41 and the second connection portion 42. This can provide the following effects. In the event of a vehicle collision, the subframe 30 is bent downward from the bent portion 43 as a starting point, and therefore, the subframe 30 can be rotated downward using the bent portion 43 as a fulcrum in accordance with the "lever principle". Therefore, the downward load can be efficiently generated in the fixing member 60. Therefore, the connection member 50 can be more easily broken.

The technical scope of the present invention is not limited to the above-described embodiments, and includes embodiments in which various modifications are made to the above-described embodiments within a scope not departing from the gist of the present invention. That is, the configuration and the like described in the above embodiment are merely examples, and can be modified as appropriate.

For example, in the above embodiment, the side frame is taken as the front side frame 20 as an example, but the present invention is not limited thereto. For example, the side frames may be rear side frames. At this time, the subframe 30 may be disposed at the rear side of the base frame 10 and below the rear side frame. That is, the vehicle body structure 1 may be applied to the rear side of the vehicle.

In the above embodiment, the fixing member 60 has been described as having the bolt and the nut, but the present invention is not limited thereto. For example, the fixing member 60 may be a fastener, a rivet, or the like.

In addition, the components in the above-described embodiments may be replaced with known components as appropriate without departing from the scope of the present invention.

Claims

1. A vehicle body structure characterized in that,

Comprising:

A base frame disposed at the center in the front-rear direction of the vehicle body;

a sub-frame disposed on one side of the base frame in a vehicle body front-rear direction and disposed below a side frame extending in the vehicle body front-rear direction;

A connecting member connecting the base frame and the side frame; and

A fixing member that fixes the connection member and the subframe,

An abutting wall that abuts the connecting member from below is formed on the base frame,

An opening portion opened in the vertical direction is formed in the abutting wall,

An opposing portion that faces the abutting wall from below is formed at an end portion of the subframe on the side of the base frame,

The fixing member is coupled to the coupling member and the facing portion through the opening portion.

2. The vehicle body structure according to claim 1,

The fixing member has: a tubular bushing coupled to the subframe and abutting against the connection member on an inner side of the opening; and a bolt and a nut that fix the connecting member and the facing portion via the boss.

3. The vehicle body structure according to claim 1,

The connecting member has: a bottom wall abutting against the abutting wall from above; and a peripheral wall formed separately from the bottom wall.

4. The vehicle body structure according to claim 2,

5. The vehicle body structure according to claim 3,

The base frame has an overlapping portion that overlaps with the peripheral wall in a thickness direction of the peripheral wall.

6. The vehicle body structure according to claim 4,

7. The vehicle body structure according to claim 3,

Further comprises a tunnel cross member supporting a tunnel portion at the center in the vehicle width direction of the floor panel and having an inverted U-shape as viewed from the front-rear direction of the vehicle body,

The peripheral wall has a connecting recess portion that extends along a vehicle width direction outer side portion of the tunnel cross member while being recessed inward in the vehicle width direction, and is connected to the tunnel cross member.

8. The vehicle body structure according to claim 4,

9. The vehicle body structure according to claim 5,

10. The vehicle body structure according to claim 6,

11. The vehicle body structure according to any one of claims 3 to 10,

The peripheral wall has a ridge line portion that is continuous with the ridge line of the side frame and that is recessed inward of the peripheral wall.

12. The vehicle body structure according to claim 1,

the base frame has an inclined surface that is inclined so as to be located more downward toward the center in the front-rear direction of the vehicle body, starting from the outer peripheral edge of the abutment wall.

13. The vehicle body structure according to claim 12,

The base frame is provided with a vertical wall that protrudes upward from a portion of the inclined surface on the side opposite to the abutment wall.

14. the vehicle body structure according to claim 1,

A lower arm support portion that supports a lower arm of a suspension is provided between the sub frame and the side frame on the opposite side of the base frame of the connection member in the vehicle body front-rear direction.

15. The vehicle body structure according to claim 1,

the subframe has: a first connecting portion connected to an end portion of the side frame opposite to the base frame in a vehicle body front-rear direction; a second connecting portion connected to the side frame between the first connecting portion and the facing portion; and a bent portion bent downward between the first connection portion and the second connection portion.