Vehicle undercarriage

Abstract

This provides a vehicle understructure that can more effectively prevent changes in seat posture. [Solution] The vehicle understructure comprises a pair of side members 10, a seat cross member 20 whose ends in the vehicle width direction are connected to each of the pair of side members 10, a seat frame 26 attached to the seat cross member 20 via an outer mounting point 30o and an inner mounting point 30i located inward in the vehicle width direction from the outer mounting point 30o, and a cross bulk 52 attached to the seat cross member 20 closer to the inner mounting point 30i than the outer mounting point 30o, to locally reinforce the seat cross member 20.

Description

Technical Field

[0001] This specification discloses a vehicle underbody structure having a pair of side members and a seat cross member to which a seat frame is fastened.

Background Art

[0002] Generally, in a vehicle, two seats functioning as a driver's seat and a passenger seat are arranged side by side in the vehicle width direction. The frame of such a seat is attached to a skeletal member called a seat cross member. The seat cross member is a skeletal member extending in the vehicle width direction, and both ends thereof are fastened to a skeletal member called a side member. Usually, two seat cross members are arranged at intervals in the vehicle front-rear direction.

[0003] The left and right ends on the front side of the seat frame are attached to the front seat cross member, and the left and right ends on the rear side of the seat frame are attached to the rear seat cross member. Therefore, usually, the four corners of the seat frame are attached to the seat cross member via four attachment points.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventionally, the rigidity at each of these four attachment points was significantly different from each other. Specifically, the rigidity at the attachment points located on the outer side in the vehicle width direction was significantly higher than the rigidity at the attachment points located on the inner side in the vehicle width direction. As a result, when a load is applied to the vehicle, the periphery of the attachment points on the inner side in the vehicle width direction is more likely to deform than the periphery of the attachment points on the outer side in the vehicle width direction. And thereby, there was a problem that the posture of the seat changed and the comfort of the occupant was impaired.

[0006] Furthermore, Patent Document 1 discloses a structure in which a reinforcing member called a bulkhead is placed at the vehicle width direction end of the cross member. According to this technology, the impact force during a side collision is effectively absorbed by the bulkhead and the center cross member. However, in the case of the technology of Patent Document 1, the rigidity at the vehicle width direction end of the cross member differs greatly from the rigidity at the center in the vehicle width direction. Due to this difference in rigidity, the center of the cross member changes more than the ends when the vehicle is in motion. As a result, the posture of the seat attached to the cross member is more likely to change.

[0007] Therefore, we disclose a vehicle understructure that can more effectively prevent changes in seat posture. [Means for solving the problem]

[0008] The vehicle understructure disclosed herein is characterized by comprising: a pair of side members; a seat cross member whose ends in the vehicle width direction are coupled to each of the pair of side members; a seat frame attached to the seat cross member via an outer mounting point and an inner mounting point located inward in the vehicle width direction from the outer mounting point; and a cross bulk attached to the seat cross member closer to the inner mounting point than the outer mounting point, to locally reinforce the seat cross member.

[0009] This configuration increases the rigidity around the inner mounting point, reducing the difference in rigidity between the inner and outer mounting points. As a result, the roll of the seat is effectively suppressed.

[0010] Furthermore, the device may have a battery pack positioned below the sheet cross member, the battery pack comprising a battery case having an upper case and a lower case, cell modules housed within the battery case, and a resin board filled between the upper surface of the cell modules and the upper case and bonded to both the cell modules and the upper case, the sheet cross member may be fixed to the upper case.

[0011] By placing a resin board inside the battery case, the surface rigidity of the upper case, which functions as the floor of the vehicle's interior, is improved. This, in turn, improves the overall rigidity of the seat cross member, suppressing the seat's tilt in the roll direction.

[0012] Furthermore, the seat cloth comprises a front seat cloth and a rear seat cloth located behind the front seat cloth, and the front seat cloth and the rear seat cloth each have an outer mounting point, an inner mounting point, and a bulkhead for the cloth, and the rigidity of the bulkhead for the cloth of the rear seat cloth may be higher than the rigidity of the bulkhead for the cloth of the front seat cloth.

[0013] This configuration reduces the difference in rigidity between the front and rear mounting points, further suppressing the movement of the seat.

[0014] Furthermore, the seat cross member has an upper flange coupled to the upper surface of the side member and a lateral flange coupled to the inner surface of the side member in the vehicle width direction, and the coupling force between the lateral flange and the side member may be less than the coupling force between the upper flange and the side member.

[0015] By reducing the bonding force of the lateral flange, the rigidity against vertical loads at the outer mounting point is lowered, and the difference in rigidity between the outer and inner mounting points is reduced. As a result, the rolling of the sheet is suppressed. [Effects of the Invention]

[0016] According to the structure disclosed herein, variations in rigidity in the seat cross member are suppressed, thereby more effectively preventing changes in the posture of the seat frame attached to the seat cross member, and consequently, the seat itself. [Brief explanation of the drawing]

[0017] [Figure 1] This is a perspective view of the main components of the underside of the vehicle. [Figure 2] This is a cross-sectional view of AA in Figure 1. [Figure 3] Figure 2 is a cross-sectional view of BB. [Figure 4] This is a schematic diagram showing the movement of the sheet when a cross-type bulkhead is present. [Figure 5] This is a schematic diagram showing the movement of the seat when there is no bulkhead for crossing. [Figure 6] This is a perspective view of the area around the joint between the seat cross member and the side member. [Modes for carrying out the invention]

[0018] Hereinafter, the vehicle underbody structure will be described with reference to the drawings. FIG. 1 is a perspective view of the main elements of the vehicle underbody. Also, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a cross-sectional view taken along line B-B in FIG. 2. This vehicle has two seats arranged in the vehicle width direction. In FIG. 1, only the seat frame 26 that supports each seat is shown. Below the seat frame 26, the vehicle frame is arranged. Specifically, the vehicle has a pair of side members 10 and a plurality of cross members 12, 14, 20. The side member 10 is a skeletal member that is long in the vehicle front-rear direction. The front ends of each of the pair of side members 10 are connected by the front cross member 12. Also, the rear ends of each of the pair of side members 10 are connected by the rear cross member 14. These side members 10, front cross member 12, and rear cross member 14 are all hollow members having a substantially rectangular cross section. The side members 10, front cross member 12, and rear cross member 14 may be formed by, for example, extrusion molding, or may be formed by joining a plurality of panel members. The area surrounded by these side members 10, front cross member 12, and rear cross member 14 is the floor area 15 that functions as the floor surface of the passenger compartment.

[0019] Between the front cross member 12 and the rear cross member 14, a front seat cross member 20F and a rear seat cross member 20R are provided. Hereinafter, when the front seat cross member 20F and the rear seat cross member 20R are not distinguished, they are referred to as "seat cross member 20". The front seat cross member 20F and the rear seat cross member 20R are arranged at intervals in the vehicle front-rear direction. Both ends in the vehicle width direction of the front seat cross member 20F are joined to the pair of side members 10. Both ends in the vehicle width direction of the rear seat cross member 20R are also joined to the pair of side members 10. These two seat cross members 20 are also hollow members having a substantially rectangular cross section and are formed, for example, by extrusion molding or by joining a plurality of panel materials.

[0020] A seat frame 26 is attached above the seat cross member 20. The seat frame 26 is roughly divided into a main body 27 that supports the seat cushion and the seat back, and a seat rail 28 that slidably holds the main body 27. One seat frame 26 has a pair of seat rails 28 spaced apart in the vehicle width direction. Near the front end of each seat rail 28 is attached to the front seat cross member 20F, and near the rear end of each seat rail 28 is attached to the rear seat cross member 20R.

[0021] Hereinafter, the location where the seat rail 28 is attached to the seat cross member 20 will be referred to as the "attachment point 30". Also, when viewed from one seat frame 26, the attachment point 30 on the outer side in the vehicle width direction is called the "outer attachment point 30o", and the attachment point 30 on the inner side in the vehicle width direction is called the "inner attachment point 30i". Therefore, one seat frame 26 is attached to the seat cross member 20 via four attachment points 30, that is, the front inner attachment point 30i, the front outer attachment point 30o, the rear inner attachment point 30i, and the rear outer attachment point 30o. Here, the attachment form of the seat rail 28 to the seat cross member 20 is not particularly limited. For example, the seat rail 28 may be attached to the seat cross member 20 via a fastening member such as a bolt, or may be attached to the seat cross member 20 by welding.

[0022] A battery pack 36 is arranged below the frames 10, 12, 14, 20. The battery pack 36 stores the electric power required for the vehicle to run. As shown in FIG. 2, the battery pack 36 has a cell module 46, a battery case 38, and a resin board 48. The cell module 46 is a component in which a plurality of battery cells are modularized. The battery cell is a rechargeable secondary battery, for example, a lithium-ion secondary battery. The cell module 46 is configured by connecting a plurality of battery cells in series or in parallel. The number of cell modules 46 included in one battery pack 36 may be one or more. In the illustrated example, a plurality of cell modules 46 are arranged inside the battery case 38 so as to line up in four columns in the vehicle width direction.

[0023] The battery case 38 is a container that houses multiple cell modules 46. The battery case 38 is broadly divided into a lower case 44 and an upper case 40. The lower case 44 is roughly box-shaped with an opening facing upwards. The cell modules 46 are arranged in the internal space of this lower case 44. The upper case 40 is a lid member that covers the upper end opening of the lower case 44 from above. Flanges 40F and 44F are formed on the periphery of the lower case 44 and the periphery of the upper case 40, respectively, that protrude horizontally outwards. The flange 40F of the upper case 40 is superimposed on the flange 44F of the lower case 44 and bonded to the flange 44F of the lower case 44. The upper and lower superimposed flanges 40F and 44F are screwed and fastened to the bottom surfaces of the side member 10, the front cross member 12, and the rear cross member 14 via fastening members such as bolts.

[0024] Here, the external shape of the battery pack 36 is approximately the same as the external shape of the floor area 15 enclosed by the pair of side members 10, the front cross member 12, and the rear cross member 14. Therefore, when the battery pack 36 is fastened to the side members 10 and the cross members 12 and 14, the floor area 15 is covered by the battery pack 36. In this example, the upper case 40 of the battery pack 36 is used as the floor panel of the vehicle compartment.

[0025] A resin board 48 is further provided between the cell module 46 and the upper case 40. The resin board 48 is a board member made of resin. This resin board 48 is joined to both the top surface of the cell module 46 and the bottom surface of the upper case 40. The resin board 48 is provided to protect the cell module 46 while ensuring the rigidity of the upper case 40. In other words, in this example, as described above, the upper case 40 is used as a floor panel. Therefore, various loads act on the top surface of the upper case 40. If these loads are transmitted to the cell module 46, it will lead to deterioration or damage to the cell module 46. Therefore, a resin board 48 is provided between the cell module 46 and the upper case 40 to improve the surface rigidity of the upper case 40.

[0026] A patch 50 is joined to the upper surface of the upper case 40 at a position corresponding to the seat cross member 20. The patch 50 is a member that interposes between the seat cross member 20 and the upper case 40 and connects the two. Specifically, the patch 50 is a panel member in which only the ends are joined to the upper case 40, and the central part is raised above the ends. The bottom surface of the seat cross member 20 is screwed or welded to the upper surface of the patch 50, thereby fixing the seat cross member 20 to the upper case 40. Of course, the seat cross member 20 may also be fixed directly to the upper case 40 without the patch 50.

[0027] As is clear from Figures 2 and 3, a cross bulk 52 is positioned inside the seat cross member 20. The cross bulk 52 is a member that locally reinforces the seat cross member 20. In this example, the cross bulk 52 has a top surface that is joined to the upper wall of the seat cross member 20, and a pair of legs that extend downward from both ends of the top surface in the vehicle's longitudinal direction. The lower ends of the legs are joined to the lower wall of the seat cross member 20. As shown in Figure 2, the cross bulk 52 is provided in a position closer to the inner mounting point 30i than to the outer mounting point 30o. The reason for providing such a cross bulk 52 will be explained with reference to Figures 4 and 5.

[0028] Figure 5 is a schematic diagram showing the movement of the seat when the cross bulkhead 52 is absent. When the vehicle is in motion, vibrations caused by unevenness in the road surface are transmitted to the side member 10, causing the side member 10 to vibrate vertically. In this case, when the cross bulkhead 52 is absent, the area around the inner mounting point 30i deforms more significantly than the area around the outer mounting point 30o. This is because the area around the inner mounting point 30i has lower rigidity than the area around the outer mounting point 30o. In other words, the outer mounting point 30o is closer to the connection point with the side member 10 than the inner mounting point 30i, and the area around the outer mounting point 30o is reinforced in strength by the side member 10. Therefore, when the cross bulkhead 52 is absent, the rigidity differs significantly between the area around the inner mounting point 30i and the area around the outer mounting point 30o. As a result, when the side member 10 vibrates, the area around the inner mounting point 30i of the seat cross member 20 deforms more significantly than the area around the outer mounting point 30o.

[0029] If the deformation at the inner mounting point 30i and the outer mounting point 30o differs significantly, the seat frame 26 attached to the seat cross member 20, and consequently the occupant seated in the seat, will swing in the roll direction, as shown by the solid line in Figure 5. This significantly impairs occupant comfort.

[0030] On the other hand, in this example, as described above, a cross bulk 52 is provided around the inner mounting point 30i so that the rigidity of the inner mounting point 30i is approximately the same as the rigidity of the outer mounting point 30o. As a result, when vibration is input to the side member 10, the amount of deformation around the inner mounting point 30i and the amount of deformation around the outer mounting point 30o can be made approximately the same. This effectively suppresses the swaying of the seat frame 26, and consequently the occupant, in the roll direction, as shown by the solid line in Figure 4. As a result, a high level of occupant comfort can be maintained.

[0031] Typically, a larger load is more likely to be applied to the rear seat crossmember 20R than to the front seat crossmember 20F. This is because the load from the occupant's buttocks is more easily transmitted to the rear seat crossmember 20R. Therefore, in the absence of the cross bulkhead 52, the area around the inner mounting point 30i of the rear seat crossmember 20R is more prone to deformation than the area around the inner mounting point 30i of the front seat crossmember 20F. To suppress this difference in deformation, the rigidity of the cross bulkhead 52 attached to the rear seat crossmember 20R may be made higher than that of the cross bulkhead 52 attached to the front seat crossmember 20F. For example, the plate thickness or width of the rear cross bulkhead 52 may be made greater than that of the front cross bulkhead 52. Alternatively, the rear seat crossmember 20R may have more cross bulkhead 52 than the front seat crossmember 20F. For example, the front seat cross member 20F may have a cross bulk 52 placed only directly below the inner mounting point 30i, while the rear seat cross member 20R may have cross bulk 52 placed on both sides in the vehicle width direction, flanking the inner mounting point 30i. In any case, by using the cross bulk 52 to suppress variations in rigidity at the four mounting points 30, the tilt of the seat frame 26 and, consequently, the occupant's posture can be suppressed, thereby improving occupant comfort.

[0032] Furthermore, in this example, the battery pack 36 is positioned below the seat cross member 20, and the seat cross member 20 is fixed to the upper case 40. In addition, a resin board 48 is placed between the upper case 40 and the cell module 46 to improve the surface rigidity of the upper case 40. As a result, the rigidity of the seat cross member 20 is reinforced by the upper case 40 and the resin board 48. This effectively suppresses local deformation of the seat cross member 20. Consequently, the oscillation of the seat frame 26, and thus the tilting of the occupant's posture, can be suppressed more effectively.

[0033] By the way, in the explanation so far, the rigidity around the inner mounting point 30i is increased by using the cross bulk 52. However, in addition to this configuration, the rigidity variation may be suppressed by reducing the rigidity around the outer mounting point 30o. For example, in order to reduce the rigidity around the outer mounting point 30o, the bonding force between the sheet cross member 20 and the side member 10 may be reduced. Figure 6 is a perspective view of the area around the joint between the sheet cross member 20 and the side member 10. The cross marks in Figure 6 indicate welding points. As shown in Figure 6, the sheet cross member 20 has an upper flange 54 that is superimposed on and bonded to the upper surface of the side member 10, and a lateral flange 56 that is superimposed on and bonded to the inner surface of the side member 10 in the vehicle width direction. Normally, the upper flange 54 is susceptible to loads in the longitudinal direction, and the lateral flange 56 is susceptible to loads in the vertical direction.

[0034] In the example shown in Figure 6, the bonding force between the lateral flange 56 and the side member 10 is made smaller than the bonding force between the upper flange 54 and the side member 10. Specifically, the number of welding points between the lateral flange 56 and the side member 10 (2 in the illustrated example) is made smaller than the number of welding points between the upper flange 54 and the side member 10 (4 in the illustrated example). As a result, the bonding force between the seat cross member 20 and the side member 10 is reduced, making the seat cross member 20 more mobile in the vertical direction. In other words, the rigidity of the end of the seat cross member 20, i.e., around the outer mounting point 30o, is reduced. Consequently, variations in rigidity in the seat cross member 20 are suppressed, and local deformation of the seat cross member 20, and consequently the tilting of the occupant's posture, are effectively suppressed.

[0035] As described above, a single seat frame 26 has four mounting points 30. By suppressing variations in rigidity at each of these four mounting points 30, local deformation of the seat cross member 20, and consequently the tilting of the occupant's posture while seated, is effectively suppressed. This improves occupant comfort. It should be noted that the configurations described so far are all examples, and other configurations may be modified as appropriate, as long as the configuration of claim 1 is met. For example, in the above description, the upper case 40 of the battery pack 36 is used as a floor panel. However, a separate panel material that functions as a floor panel may be provided in addition to the battery pack 36. In that case, the panel material that functions as a floor panel is joined to the side member 10, the front cross member 12, and the rear cross member 14. Also, the seat cross member 20 is fixed to the floor panel instead of the upper case 40. Furthermore, the vehicle may have a configuration without a battery pack 36. Therefore, the vehicle may be an engine-powered automobile that does not have a motor and runs on engine power. Furthermore, the shape and number of the cross bulk 52 may be changed as appropriate, provided that it is positioned closer to the inner mounting point 30i than to the outer mounting point 30o. Also, the cross bulk 52 may be mounted on the outside of the sheet cross member 20, not just inside, as long as it provides localized reinforcement to the sheet cross member 20. [Explanation of Symbols]

[0036] 10 Side members, 12 Front cross members, 14 Rear cross members, 15 Floor area, 20F Front seat cross members, 20R Rear seat cross members, 26 Seat frame, 27 Main body, 28 Seat rails, 30i Inner mounting point, 30o Outer mounting point, 36 Battery pack, 38 Battery case, 40 Upper case, 44 Lower case, 46 Cell module, 48 Resin board, 50 Patch, 52 Cross bulk, 54 Upper flange, 56 Side flange.

Claims

1. A pair of side members, Both ends in the vehicle width direction are connected to the respective pair of side members, and A seat frame is attached to the seat cross member via an outer mounting point and an inner mounting point located inward in the vehicle width direction from the outer mounting point, A cross bulk is attached to the seat cross member at a position closer to the inner mounting point than the outer mounting point, and locally reinforces the seat cross member. A vehicle understructure characterized by having the following features.

2. The vehicle understructure according to claim 1, further, It has a battery pack located below the aforementioned seat cross member, The aforementioned battery pack is A battery case having an upper case and a lower case, The cell module housed in the aforementioned battery case, A resin board is filled between the upper surface of the cell module and the upper case and bonded to both the cell module and the upper case, The seat cross member is fixed to the upper case, A vehicle understructure characterized by the following features.

3. The vehicle understructure according to claim 1, It has a front seat cloth and a rear seat cloth located behind the front seat cloth, The front seat cloth and the rear seat cloth each have the outer mounting point, the inner mounting point, and the bulk for the cloth, The rigidity of the bulkhead for the rear seat cloth is higher than that of the bulkhead for the front seat cloth. A vehicle understructure characterized by the following features.

4. The vehicle understructure according to claim 1, The seat cross member has an upper flange coupled to the upper surface of the side member and a lateral flange coupled to the inner surface of the side member in the vehicle width direction. The bonding force between the lateral flange and the side member is less than the bonding force between the upper flange and the side member. A vehicle understructure characterized by the following features.

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