1. A vehicle body lower portion structure is provided with:

a rocker disposed at a lateral lower portion of the vehicle body and extending in a vehicle body front-rear direction;

a power source disposed alongside the rocker;

an energy absorbing member that is hollow and located below the rocker;

a sleeve that penetrates the upper plate of the energy absorbing member, has an upper end abutting against the rocker, and has a lower end abutting against the lower plate of the energy absorbing member, and is welded to the upper plate,

the energy absorbing member includes: a first vertical plate, a second vertical plate and a third vertical plate which connect the upper plate and the lower plate; and a diagonal brace which is arranged on the upper portion of the frame,

the first vertical plate, the second vertical plate, and the third vertical plate are arranged in this order in the vehicle width direction,

the sleeve passes between the first longitudinal plate and the second longitudinal plate,

the inclined strut connects a first inner angle formed by the second longitudinal plate and the upper plate in a crossed manner and a second inner angle formed by the third longitudinal plate and the lower plate in a crossed manner,

the ratio of the thickness of the upper plate to the thickness of the sleeve is 0.5 to 2.0.

2. The vehicle body lower structure according to claim 1,

in the upper plate, a thickness under a weld joint joining the sleeve and the upper plate, that is, a thickness under the weld joint is thicker than a thickness of a portion separated from the weld joint,

the ratio of the thickness under the weld to the thickness of the sleeve is 0.5 to 2.0.

3. The vehicle body lower structure according to claim 1 or 2,

the power source is supported by the energy absorbing member.

4. The vehicle body lower portion structure according to any one of claims 1 to 3,

the rocker and the energy absorbing member are joined together with a bolt passing through the bushing.

Background

In an electric vehicle, a power supply for supplying electric power to a motor for traveling is sometimes disposed near a rocker. The power source is a battery, a fuel cell, or the like. The rocker is a frame extending in the front-rear direction of the vehicle body at the lateral lower portion of the vehicle body. Rocker beams are also sometimes referred to as rocker panels.

In order to protect the power supply from an impact of a side collision, a member (energy absorbing member) that absorbs energy of the impact may be disposed along the rocker. In japanese patent laid-open publication No. 2018-75939, an example of an energy absorbing member is disclosed. An energy absorbing member described in japanese patent application laid-open No. 2018-75939 extends in the front-rear direction of a vehicle body and is in contact with the lower side of a rocker. In order to achieve both the function of absorbing energy and the strength, the energy absorbing member is hollow and has a reinforcing plate inside. Hereinafter, for simplicity of explanation, the Energy Absorbing member is referred to as an EA member (Energy Absorbing member).

Disclosure of Invention

In order to secure a gap between the rocker and the EA member, a sleeve (tube) is sometimes used. The sleeve penetrates the upper plate of the EA member, and the upper end abuts the rocker and the lower end abuts the lower plate of the EA member. The sleeve is welded to the upper plate of the EA member. In addition to such a structure, in order to improve the strength of the EA member, a reinforcing plate is provided inside the EA member. If the reinforcing plate is concentrated in the vicinity of the welding point between the sleeve and the upper plate, a large amount of heat during welding may be diffused to the reinforcing plate, and the sleeve may not be firmly welded to the upper plate.

In the vehicle body lower portion structure disclosed in the present specification, the EA member is a hollow beam, and includes first, second, and third vertical plates that connect the upper plate and the lower plate. The first, second, and third vertical plates are arranged in this order along the vehicle width direction. The sleeve passes between the first longitudinal plate and the second longitudinal plate. The EA member further includes a diagonal brace. The diagonal brace connects a first inner angle formed by the second longitudinal plate and the upper plate and a second inner angle formed by the third longitudinal plate and the lower plate. The diagonal bracing improves the strength of the EA member. On the other hand, the upper end of the diagonal brace is connected to a first inner corner (a corner formed by the intersection of the upper plate and the second vertical plate) near the sleeve. Therefore, heat generated when the sleeve and the upper plate are welded is diffused to the stay, and the welding strength between the sleeve and the upper plate may be insufficient. To cope with this problem, the ratio of the thickness of the first vertical plate located on the opposite side of the diagonal brace with the sleeve interposed therebetween to the thickness of the upper plate is set to 0.5 to 2.0.

In the case of welding two intersecting plates, if the ratio of the thicknesses of the two plates is 0.5 or more and 2.0 or less, the heat of welding is uniformly diffused to the two plates, and uniform welding is achieved. Namely, a higher welding strength is obtained. In the vehicle body lower portion structure disclosed in the present specification, the grommet is passed between the first longitudinal plate and the second longitudinal plate, and the stay is provided in the vicinity of the second longitudinal plate. Although there is a possibility that the welding strength between the upper plate and the sleeve may decrease in the vicinity of the second vertical plate, the upper plate and the sleeve can be welded at a high strength in the vicinity of the first vertical plate, and therefore the decrease in the welding strength in the vicinity of the second vertical plate can be compensated for. As a result, sufficient welding strength is ensured between the sleeve and the upper plate.

The ratio of the thickness of the upper plate to the thickness of the first vertical plate at the portion welded to the sleeve may be 0.5 to 2.0 as described above. By reducing the thickness of the upper plate at the portion separated from the welded portion, the EA member can be reduced in weight. In particular, it is preferable to reduce the thickness of the upper plate at a portion located further to the outside in the vehicle width direction than the sleeve in the vehicle width direction and apart from the welded portion.

The diagonal brace is effective for preventing deformation of the EA member in a structure in which the power source is supported by each of the pair of EA members. The rocker and the EA member may also be joined together with bolts passing through the sleeves. Further, a partition wall may be disposed as a reinforcement inside the rocker. In this case, the rocker, the partition wall, and the EA member are preferably joined together by bolts.

Details and further improvements of the technology disclosed in the present specification are described in the following "detailed description of the preferred embodiments".

Drawings

Fig. 1 is a perspective view of a vehicle body.

Fig. 2 is a cross-sectional view of the vehicle body taken along plane II of fig. 1.

Fig. 3 is an enlarged view of a range surrounded by a broken line III of fig. 2.

Fig. 4 is a top view around a sleeve of an upper plate of an EA member.

Detailed Description

A vehicle body lower portion structure 3 of the embodiment will be explained with reference to the drawings. In fig. 1, a perspective view of a vehicle body 2 is shown. The "left" of the coordinate system of fig. 1 indicates the "left" when the front is viewed from the rear of the vehicle. In the following figures, the meaning of "left" of the coordinate system is the same.

The vehicle body 2 includes a pair of rocker beams 10. The pair of rocker beams 10 are disposed at respective lateral lower portions of the vehicle body 2 in the vehicle width direction. The rocker 10 is an elongated beam, and extends in the front-rear direction of the vehicle body 2. The lower end of the center pillar 51 is connected to the substantial center of each rocker 10 in the longitudinal direction. The pair of rocker beams 10 and the center pillar 51 are one type of frame that ensures the strength of the vehicle body 2. The rocker 10 is manufactured by press working of a metal plate (typically, a steel plate).

The battery pack 40 and the floor panel 50 are disposed between the pair of rocker beams 10. In the battery pack 40, a plurality of battery cells are included. The plurality of battery cells are connected in series, and are capable of outputting a high voltage. The battery pack 40 (battery cell) supplies electric power to a not-shown traveling motor.

The floor panel 50 corresponds to the floor of the vehicle compartment. Both ends of the floor panel 50 in the vehicle width direction are fixed to the pair of rocker beams 10, respectively. The battery pack 40 is disposed under the floor panel 50. As will be described in detail later, an energy absorbing member (not shown in fig. 1) is disposed along the rocker, and the battery pack 40 is supported by the pair of rockers 10 via the energy absorbing member. The battery pack 40 may be supported by the rocker 10 via the energy absorbing member and may be supported by the rocker 10 via the floor panel 50.

The energy absorbing members are arranged at both sides of the battery pack 40 in the vehicle width direction. As described above, for convenience of description, the Energy Absorbing member is referred to as an EA member (Energy Absorbing member).

In fig. 2, a cross section cut at plane II of fig. 1 is shown. Fig. 2 shows a vehicle body lower portion structure 3 at the left side of the vehicle body 2. As described above, the battery pack 40 is fixed to the rocker 10 via the EA member 20 (energy absorbing member 20) at the lower right and lower left of the vehicle, respectively. The vehicle body 2 is bilaterally symmetrical, and the structure of the lower portion on the right side of the vehicle body 2 is also the same as that of fig. 2. That is, the vehicle body lower portion structure 3 of the embodiment includes a pair of rocker beams 10 and a pair of EA members 20, and each EA member 20 is disposed along the corresponding rocker beam 10. Hereinafter, a structure of a lower portion on the left side of the vehicle body 2 will be explained.

The battery pack 40 includes a lower case 41, an upper case 42, and a plurality of battery cells 43. A container is formed by the lower case 41 and the upper case 42, and a plurality of battery cells 43 are housed therein. The lower casing 41 and the upper casing 42 are respectively provided with flanges, which are joined to each other, and the lower casing 41 and the upper casing 42 constitute a container.

The rocker 10 is composed of a rocker inner panel 11 and a rocker outer panel 12. The rocker inner panel 11 has a side-facing angular U-shape (groove shape), and has a lower flange 11a and an upper flange 11 b. The lower flange 11a extends downward from the lower edge of the U-shape facing the side surface of the rocker inner panel 11, and the upper flange 11b extends upward from the upper edge of the U-shape facing the side surface of the rocker inner panel 11. The rocker outer panel 12 also has the same shape as the rocker inner panel 11, and has a lower flange 12a and an upper flange 12b that are opposed to the lower flange 11a and the upper flange 11b of the rocker inner panel 11, respectively. The lower flanges 11a, 12a are welded, and the upper flanges 11b, 12b are welded, thereby completing the lower side beam which is a hollow square beam. In fig. 2, the rocker outer panel 12 is depicted as being separated from the rocker inner panel 11 to facilitate understanding.

A bulkhead 60 is disposed inside the rocker 10. The bulkhead 60 is a reinforcement that improves the strength of the rocker 10. The bulkhead 60 is attached to the inner side of the rocker inner panel 11 before the rocker inner panel 11 and the rocker outer panel 12 are joined. The bulkhead 60 is fixed to the rocker inner panel 11 by welding or bolts (not shown). The nut 32 is fixed to the inside of the spacer 60. The nut 32 is fixed to the rocker inner panel 11 by welding.

The EA member 20 is composed of a first EA member 21 and a second EA member 22. The first EA member 21 is disposed below the rocker 10. The second EA member 22 is disposed between the first EA member 21 and the battery pack 40. The first EA member 21 is fixed to the rocker 10. The second EA member 22 is coupled to the first EA member 21 and also coupled to the battery pack 40.

The EA member 20 (the first EA member 21 and the second EA member 22) is a hollow square beam. The EA member 20 extends in the front-rear direction of the vehicle along the rocker 10. The EA member 20 absorbs energy at the time of a vehicle side collision and protects the battery pack 40. The EA member 20 is crushed in the vehicle width direction by the impact of the collision, and absorbs the collision energy. Although the rocker also contributes to the absorption of the impact energy, the impact energy cannot be completely absorbed only by the rocker 10. Therefore, the hollow EA member 20 is disposed along the rocker.

The support plate 44 extends from the lower surface of the battery pack 40 toward the outer side in the vehicle width direction. The support plates 44 are also coupled together with the first EA member 21 by the bolts 31 and the nuts 32, and are fixed to each other. By fixing the support plate 44 extending from the battery pack 40 to the first EA member 21, the battery pack 40 is firmly fixed to the EA member 20.

A coupling structure of the first EA member 21 and the second EA member 22 will be described. A flange 26 extends from an end edge of the upper plate of the first EA member 21 toward the vehicle center. The second EA member 22 is fixed to the flange 26 of the first EA member 21 by a bolt 33 and a nut 34. A support plate 44 extending from the battery pack 40 is also fixed to the second EA member 22 by the bolt 33. The second EA member 22 is sandwiched and fixed by the flange 26 of the first EA member 21 and the support plate 44 of the battery pack 40. The second EA member 22 is bonded on the side of the lower case 41 of the battery pack 40. The battery pack 40 and the second EA member 22 are firmly joined together by the adhesive and the bolts 33.

The EA member 20 is divided into a first EA member 21 fixed to the rocker 10 and a second EA member 22 bonded to the battery pack 40. The second EA member 22 is attachable to and detachable from the first EA member 21. The EA member 20 can cope with a variety of automobiles of different vehicle widths by adjusting the combination of the first EA member 21 and the second EA member 22.

The strength of the EA member 20 is predetermined by a simulation experiment or the like to effectively absorb collision energy. The internal space of the first EA member 21 is divided into several cell spaces CS by a plurality of vertical plates 25 connecting the upper plate 23 and the lower plate 24. Diagonal braces 27 extending diagonally within the rectangular cell space are provided within the several cell spaces. The strength of the first EA member 21 can be adjusted by adjusting the number and thickness of the vertical plates 25 and the diagonal braces 27. The strength of the EA member 20 is set at least lower than that of the battery pack 40. However, the EA member 20 has sufficient strength to support the battery pack 40.

The advantages achieved by the provision of the diagonal brace 27 will be explained. As shown in fig. 2, the battery pack 40 is supported by the EA member 20, and the EA member 20 is fixed to the rocker 10 by a bolt 31. The weight of the battery 40 is applied at the side of the EA member 20 near the battery 40. Therefore, a vertical shear force is applied between the battery pack 40 and the bolt 31 to the first EA member 21. The first EA member 21 is deformed by the shear force. The stay 27 suppresses deformation of the first EA member 21.

In addition, the shearing force becomes large between the battery 40 and the bolt 31, and is smaller at the side farther from the battery pack 40 than the bolt 31. Therefore, no brace is provided in the cell space CS on the side farther from the battery pack 40 than the bolt 31.

As described above, the first EA member 21 is disposed below the rocker 10, and the rocker 10 includes the flange 11a (12a) extending downward from the floor panel 13. The first EA member 21 should be arranged in such a manner as to avoid interference with the lower flange 11a (12 a). If the first EA member 21 is divided into a portion on the inner side (vehicle center side in the vehicle width direction) and a portion on the outer side of the lower flange 11a (12a), the structure of the EA member becomes complicated. In the vehicle body lower portion structure 3 of the embodiment, a collar (tubular) 30 is disposed between the first EA member 21 and the rocker 10 so as to avoid interference of the first EA member 21 with the lower flange 11a (12 a). By disposing the first EA member 21 below the lower flange 11a (12a), a first EA member having a simple shape and extending outward in the vehicle width direction from the lower flange 11a (12a) can be realized.

The sleeve 30 is a metal cylinder. In other words, the sleeve 30 is a spacer for ensuring a gap between the rocker 10 and the first EA member 21. As shown in fig. 2, the height h1 of sleeve 30 above first EA member 21 is greater than the height h2 of lower flange 11a (12 a). A gap of a distance h1 is ensured between the bottom plate 13 of the rocker 10 and the upper plate 23 of the first EA member 21 by the bushing 30. Since the height of the lower flange 11a (12a) is h2 (< h1), the lower flange 11a (12a) does not interfere with the first EA member 21. Therefore, a simple square beam shape can be adopted as the shape of the first EA member 21, and the manufacturing cost can be suppressed.

The structure around the sleeve 30 will be explained. The sleeve 30 passes through a hole provided on the upper plate 23 of the first EA member 21. The upper end of the sleeve 30 abuts against the lower surface of the bottom plate 13 of the rocker 10. The lower end of the sleeve 30 abuts the upper surface of the lower plate 24. The sleeve 30 is welded to the upper plate 23. A weld 39 is formed at a portion where the sleeve 30 and the upper plate 23 intersect.

The first EA member 21, the rocker 10, and the bulkhead 60 are collectively joined by a bolt 31 and a nut 32 that pass through the inside of the sleeve 30, and are fixed to each other.

When the battery pack 40 vibrates up and down during running, the sleeve 30 also vibrates up and down, and a vibration load in the up-down direction is applied to the rocker 10. Since the bottom plate 13 and the partition wall 60 are sandwiched between the sleeve 30 and the nut 32, the rocker 10 is less likely to be deflected by vibrations in the vertical direction of the sleeve 30.

The structure around the sleeve is explained in more detail. In fig. 3, an enlarged view of the range of the dashed rectangle III of fig. 2 is shown. As described above, the first EA member 21 is a hollow square beam and has several vertical plates 25 inside. The vertical plate 25 is coupled to the upper plate 23 and the lower plate 24 of the first EA member 21. The vertical plate 25 extends in the front-rear direction of the vehicle body 2 in the first EA member 21. The internal space of the first EA member 21 is divided into a plurality of cell spaces CS by a plurality of vertical plates 25. The cell space CS is also rectangular, and is provided with diagonal braces 27 extending in diagonal directions of the rectangle in several cell spaces. The stay 27 also extends in the front-rear direction of the vehicle body 2 in the first EA member 21.

The vertical plate 25 adjacent to the right side in the drawing of the sleeve 30 is referred to as a first vertical plate 25a, and the vertical plate 25 adjacent to the left side in the drawing of the sleeve 30 is referred to as a second vertical plate 25 b. The vertical plate 25 adjacent to the left side of the second vertical plate 25b in the drawing is referred to as a third vertical plate 25 c. In other words, the first vertical plate 25a, the second vertical plate 25b, and the third vertical plate 25c are arranged in this order from the outer side in the vehicle width direction toward the vehicle center. The sprag 27 provided in the cell space CS between the second vertical plate 25b and the third vertical plate 25c is referred to as a sprag 27 a.

The sleeve 30 passes through the cell space CS between the first vertical plate 25a and the second vertical plate 25 b. An inclined strut 27a is provided between the first vertical plate 25b and the third vertical plate 25 c. The diagonal brace 27a connects a first inner corner 28a formed by the second vertical plate 25b and the upper plate 23 intersecting with each other and a second inner corner 28b formed by the third vertical plate 25c and the lower plate 24 intersecting with each other.

The sleeve 30 and the upper plate 23 are welded together as previously described. A weld 39 is formed around the sleeve 30 on the upper plate 23. The thickness T2 below the weld 39 of the upper plate 23 is substantially equal to the thickness T1 of the sleeve 30 (the thickness T1 of the barrel of the sleeve 30) or slightly thinner than the thickness T1. The ratio of the thickness T2 of the upper plate 23 to the thickness T1 of the sleeve 30 may be 0.5 to 2.0.

In the case of welding the two plates (the upper plate 23 and the sleeve 30) that intersect each other, it is preferable that the two plates have substantially the same thickness. If the thickness is greatly different, the heat of welding is diffused in the plate having a large thickness, so that the temperature rise of the plate becomes slow as compared with the plate having a small thickness. Therefore, the temperature of the thin plate is higher than that of the plate having a large thickness at the time of welding. Therefore, in the case of a plate having a large thickness, there is a possibility that a plate having a small thickness may melt before the welding material melts. If the sheet of lower thickness melts, the strength of the welded portion will decrease. If the welding is terminated before the thin plate is melted, the thick plate cannot be sufficiently melted, and the strength of the welded portion is still reduced. If the ratio of the thickness of the two intersecting plates is 0.5 or more and 2.0 or less, the two plates are heated equally, and the best welding strength can be obtained.

A brace 27a is connected to a first inner corner 28a formed by the intersection of the second vertical plate 25b and the upper plate 23. The heat generated when the sleeve 30 and the upper plate 23 are welded is also diffused toward the diagonal brace 27 a. On the side close to the second vertical plate 25b, the sleeve 30 and the upper plate 23 may not be appropriately welded. However, since the brace is not provided on the side close to the first vertical plate 25a, the sleeve 30 and the upper plate 23 can be firmly welded.

Further, the first vertical plate 25a and the second vertical plate 25b are joined to the upper plate 23 below the weld 39. The heat of welding is also diffused to the first vertical plate 25a and the second vertical plate 25 b. Accordingly, the thickness T2 of the upper plate 23 is preferably the same as or less than the thickness T1 of the sleeve 30. That is, the thickness T2 of the upper plate 23 is preferably 0.5 times or more and 1.0 times or less (0.5T 1. ltoreq. T2. ltoreq. T1) the thickness T1 of the sleeve 30.

In fig. 4, a top view around the sleeve 30 of the upper plate 23 of the first EA member 21 is shown. The weld 39 surrounds the sleeve 30. In fig. 4, the weld 39 is shown in gray for ease of understanding. A weld 39 joins the sleeve 30 and the upper plate 23. As described above, since the brace 27a is connected to the inner corner 28a (see fig. 3) where the upper plate 23 and the second vertical plate 25b intersect, there is a possibility that the welding strength around the second vertical plate 25b is insufficient. In fig. 4, a region 39b shown by lighter gray indicates a region where the welding strength may be insufficient. On the other hand, the sleeve 30 and the upper plate 23 are firmly welded at a portion apart from the second vertical plate 25 b. In fig. 4, a region 39a shown in darker gray indicates a region where the sleeve 30 and the upper plate 23 are firmly welded. Since the half turn or more of the sleeve 30 is firmly welded to the upper plate 23, a sufficient welding strength can be secured between the sleeve 30 and the upper plate 23.

The thickness of the upper plate 23 will be explained. As described above, under the weld 39, the thickness of the upper plate 23 is T2, and the thickness T2 is 1/2 times or more and 2 times or less the thickness T1 of the sleeve. On the other hand, the thickness T3 of the upper plate 23 at the position away from the weld 39 is thinner than the thickness T2 below the weld 39. In addition, the thickness of the upper plate 23 is constant in the front-rear direction of the vehicle body 2, and has two thicknesses (thickness T2 and thickness T3) in the vehicle width direction. That is, the thickness T3 of the upper plate 23 at the position apart from the weld bead 39 is thinner than the thickness T2 in the vehicle width direction. The ratio of the thickness T2 of the upper plate 23 to the thickness T1 of the sleeve 30 is set to 0.5 or more and 2.0 or less below the weld 39. On the other hand, at a position apart from the weld bead 39 in the vehicle width direction, the thickness T3 of the upper plate 23 is made thinner than the thickness T2. With this structure, the sleeve 30 and the upper plate 23 can be firmly welded, and the first EA member 21 can be reduced in weight.

Likewise, with respect to the lower plate 24, the thickness T2 of the lower plate 24 around the sleeve 30 is the same as the thickness T2 of the upper plate 23, and the thickness T3 of the lower plate 24 at a position distant from the sleeve 30 in the vehicle width direction is thinner than the thickness T2. The lower plate 24 and the end of the sleeve 30 are coupled by a bolt 31. The thickness T2 of the lower plate 24 is increased around the sleeve 30 and the thickness T3 of the lower plate 24 is reduced at a location away from the sleeve 30. With this structure, the first EA member 21 can be made lightweight while increasing the strength of the region to be joined by the bolt 31.

Attention associated with the technique described in the embodiment will be described. In the EA member 20 (the first EA member 21, the second EA member 22), the sectional shape cut at a plane intersecting with the vehicle front-rear direction is the same regardless of the position in the vehicle front-rear direction. The EA member 20 (the first EA member 21 and the second EA member 22) is manufactured by extrusion molding of metal (typically, aluminum).

A spacer 60 is fixed to the rocker 10 by a bolt 31. A spacer plate 60 may also be fixed to the rocker 10 using a plurality of bolts. The bushing 30 may be inserted with a plurality of bolts that fix one spacer 60, and each bolt may fix the EA member 20 to the rocker 10 via the bushing 30. It is also possible to have one support plate 44 be commonly joined by a plurality of bolts with respect to one partition plate 60.

The battery pack 40 is an example of a power source. The battery pack 40 includes a plurality of battery cells. The power source disposed between the pair of rocker beams 10 is not limited to a battery pack, and may be a device housing a fuel cell or a capacitor.

The upper plate 23 of the EA member is preferably thicker between a pair of vertical plates (the first vertical plate 25a and the second vertical plate 25b) adjacent to the bolt 31 than the outer sides of the pair of vertical plates. By reducing the thickness of the upper plate 23 at a position away from the bolt 31, the amount of heat diffused to the upper plate 23 during welding can be suppressed.

Although specific examples of the present invention have been described above in detail, these are merely examples and are not intended to limit the technical scope. The techniques described in the claims include modifications and changes to the specific examples described above. The technical elements described in the present specification or the drawings are those which exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of application. Further, the techniques illustrated in the present specification or the drawings can achieve a plurality of objects at the same time, and achieving one of the objects has technical usefulness by itself.