JP7544287B2 - Body frame - Google Patents

Description

This disclosure relates to a vehicle body frame.

In vehicles such as automobiles, in order to improve the safety of passengers in the vehicle cabin during a rear-end collision, a vehicle body frame has been proposed that deforms the rear of the vehicle during a collision to absorb collision energy (see, for example, Patent Document 1).

For example, Patent Document 1 proposes a vehicle body frame in which a pair of side frames extending in the fore-and-aft direction of the vehicle at the rear of the vehicle are each provided with a first deformation promoting portion and a second deformation promoting portion.

JP 2018-39313 A

However, in the conventional configuration shown in Patent Document 1, the cross member is provided to connect a pair of side frames in the range where the first deformation promoting portion and the second deformation promoting portion are provided, so deformation of the points where the cross member is connected in the range where the first deformation promoting portion and the second deformation promoting portion of the pair of side frames are provided is hindered, impairing energy absorption performance in the event of a rear-end collision. One method of reducing the range where deformation of the side frames is hindered by the cross member in the event of a rear-end collision would be to reduce the width of the cross member in the fore-and-aft direction of the vehicle, but in this case it would be difficult to ensure sufficient strength and rigidity of the cross member.

This disclosure has been made in consideration of the above-mentioned problems, and aims to provide a vehicle body frame that can ensure sufficient strength and rigidity of the cross member while also improving energy absorption performance during a rear-end collision.

In order to achieve the above-mentioned objective, the vehicle body frame of the present disclosure comprises a pair of side frames spaced apart in the vehicle width direction and extending along the vehicle fore-and-aft direction, and a cross member connecting the pair of side frames to each other at the rear end of the vehicle, the pair of side frames having a first region extending across the vehicle fore-and-aft direction at the rear end of the vehicle and a second region extending from a front end of the first region to the front side of the vehicle, the first region being formed to have a smaller deformation strength in the vehicle fore-and-aft direction than the second region, and the cross member having a front leg portion extending in the vehicle width direction and connected to the second region, and a rear leg portion disposed away from the front leg portion toward the rear of the vehicle, extending in the vehicle width direction and connected to the first region.

According to the vehicle body frame disclosed herein, the cross member is connected to a pair of side frames at two points spaced apart in the vehicle longitudinal direction, so that the width of the cross member in the vehicle longitudinal direction at each connection point can be reduced. In addition, the rear side of each connection point is connected to a first region with low deformation strength, and the front side of the vehicle is connected to a second region, so that the width of the cross member connected to the first region in the vehicle longitudinal direction can be reduced, and the amount of deformation inhibition of the side frames by the cross member during a rear-end collision of the vehicle can be reduced. As a result, the collision energy during a rear-end collision is effectively absorbed by the first region, so that the energy absorption performance during a rear-end collision can be improved.

FIG. 2 is a perspective view showing a vehicle body frame according to the embodiment; 2 is a plan view showing details of a rearmost portion in the vehicle front-rear direction of the body frame shown in FIG. 1 . FIG. 2 is a rear view showing details of the rearmost part in the vehicle front-rear direction of the body frame shown in FIG. 1 . FIG. 2 is a side view showing details of a rearmost portion in the vehicle front-rear direction of the body frame shown in FIG. 1 as viewed from the inside in the vehicle width direction. FIG. FIG. 2 is a perspective view showing details of the cross member shown in FIG. 1 . 11 is a perspective view showing a mounting bracket for connecting a cross member to an area of the side frame other than the low strength area. FIG. FIG. 2 is a diagram showing a spare tire supported by a vehicle body frame.

Hereinafter, a vehicle rear body structure according to an embodiment will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described as the embodiment or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples.

[Overall configuration of vehicle body frame 1]
As shown in FIG. 1, the body frame 1 of the embodiment is a ladder frame (ladder-shaped frame) that includes a pair of side frames 2, 2 spaced apart in the vehicle width direction and extending along the front-to-rear direction of the vehicle, and a number of cross members 31-36, 4 that connect the pair of side frames 2, 2 to each other.

Each pair of side frames 2, 2 is constructed by connecting multiple frames 21, 22, 23 in order from the front of the vehicle. For example, the side frame 2 shown in FIG. 1 is constructed of three frames 21, 22, 23. The multiple frames 22, 23 include inner frames 221, 231 provided on the inside in the vehicle width direction and outer frames 222, 232 provided on the outside in the vehicle width direction and combined with the inner frames 221, 231, and the multiple frames 22, 23 are constructed by joining the inner frames 221, 231 and the outer frames 222, 232. For example, the inner frames 221, 231 and the outer frames 222, 232 are each constructed of a folded plate-like body (e.g., a steel plate). The connection point between the inner frames 221 and 231 is provided at a different location in the vehicle front-rear direction from the connection point between the outer frames 222 and 232.

The multiple cross members 31-36, 4 are spaced apart in the vehicle longitudinal direction, and each cross member 31-36, 4 connects a pair of side frames 2, 2 to each other. For example, the cross members 31-36, 4 are made of solid members or hollow members molded into a grooved or cylindrical shape.

[Configuration of Main Parts of Body Frame 1]
Each of the pair of side frames 2, 2 according to the embodiment has a first region 2A provided in the vehicle longitudinal direction at the rear end of the vehicle, and a second region 2B provided from the front end of the first region 2A to the vehicle front side, and the first region 2A is formed so that the deformation strength in the vehicle longitudinal direction is smaller than that of the second region 2B. The deformation strength refers to the strength or rigidity in a certain direction. Hereinafter, the first region 2A will be referred to as the low strength region 2A, and the second region 2B will be referred to as the high strength region 2B. In this embodiment, the first region 2A is provided in the rear side frame, that is, in a part of a portion extending rearward from the rear end of a kick-up portion provided on the side frame 2, 2, which is inclined upward and rearward of the vehicle.

In this embodiment, the side frame 2 includes a first frame 23 extending forward from the rear end of the vehicle, and a second frame 22 extending forward from the front end of the first frame. The plate thickness of the inner frame 231 and the outer frame 232 constituting the first frame 23 is made thinner than the plate thickness of the inner frame 221 and the outer frame 222 constituting the second frame 22, thereby reducing the deformation strength of the first frame 23 in the longitudinal direction of the vehicle, and the first frame 23 is made a low-strength region 2A, and the second frame 22 is made a high-strength region 2B. In this embodiment, the connection point between the inner frames 231 and 221 is located forward of the connection point between the outer frames 232 and 222, and in such a case, the rear side of the connection point between the outer frames 232 and 222 is defined as the low-strength region 2A. In addition, as shown in Figures 2 and 7, recesses 231a, 232a are provided along the vehicle height direction in the inner frame 231 and the outer frame 232 that constitute the first frame 23, thereby further reducing the deformation strength of the first frame 23 in the vehicle fore-and-aft direction.

The method of forming the low-strength region 2A is not limited to the above embodiment. The first frame 23 may be made into the low-strength region 2A by making the cross-sectional area of the first frame 23 smaller than that of the second frame 22, or by making the material of the first frame 23 a material with a lower compressive strength than that of the material of the second frame 22. In addition, the thickness of the inner frame 231 and the outer frame 232 constituting the first frame 23 is not different from the thickness of the inner frame 221 and the outer frame 222 constituting the second frame 22, and weak parts such as recesses and holes along the vehicle height direction or vehicle width direction are arranged in a row over the entire vehicle front-rear direction of the first frame 23, thereby reducing the deformation strength of the first frame 23 in the vehicle front-rear direction, and the first frame 23 may be made into the low-strength region 2A. In addition, the low-strength region 2A may be formed only in the rear part of the first frame 23.

It is desirable that the low-strength region 2A is provided further rearward than the passenger space of the vehicle (e.g., in the luggage compartment). It is also desirable that the high-strength region 2B is provided in the passenger space of the vehicle. In this way, the low-strength region 2A, which has a small deformation strength and is easily compressed, deforms like an accordion during a rear-end collision, but since the low-strength region 2A is located rearward of the passenger space of the vehicle, the passenger space is protected.

2 and 3, each of the pair of side frames 2, 2 has a first member 24 that protrudes outward in the vehicle width direction from the rearmost part of the low strength area 2A. The first member 24 is, for example, a cab mount bracket 25 for mounting a body (cabin) on the vehicle frame 1, and is formed by bending a plate-like body (for example, a steel plate) into an L-shape, with one side of the L-shape joined to the outer surface of the outer frame 232 in the vehicle width direction. Note that the first member 24 is not limited to the cab mount bracket 25.

A hook 26 is attached to the cab mount bracket 25 (see FIG. 1). The hook 26 is used to tow other vehicles, and is constructed by attaching a rod-shaped member 262 bent into a J-shape to a plate-shaped body 261 (e.g., a steel plate), and is attached to the outer frame 232 with the cab mount bracket 25 in between.

As shown in Figure 1, the cross member 4 at the rear end of the vehicle (the cross member as defined in the claims, hereafter simply referred to as "cross member 4") has a front leg 41 and a rear leg 42 spaced from the front leg 41 toward the rear of the vehicle so as to be connected to each of a pair of side frames 2, 2 at two connection points spaced apart in the fore-and-aft direction of the vehicle. The front leg 41 is connected to the high strength region 2B, and the rear leg 42 is connected to the low strength region 2A.

In this embodiment, the front legs 41 are inclined toward the rear of the vehicle from both outer sides in the vehicle width direction toward the inside, and the rear legs 42 are inclined toward the front of the vehicle from both outer sides in the vehicle width direction toward the inside (see FIG. 6). Furthermore, the cross member 4 has a connection part 43 that connects the front legs 41 and the rear legs 42 on the inner side in the vehicle width direction (see FIG. 6). As a result, the cross member 4 is approximately X-shaped in a plan view.

As shown in Figure 6, the front leg 41 is connected to the vehicle rear end of the second frame 22, which is the high strength region 2B, and the rear leg 42 is connected to the vehicle rear end of the first frame 23, which is the low strength region 2A. The front leg 41 has a mounting bracket 5 that connects the front leg 41 to the side frame 2. The mounting bracket 5 is provided from the second frame 22 to the first frame 23. In detail, the mounting bracket 5 is connected to the side frame 2 from the rear end of the inner frame 221 to the front end of the inner frame 231, and the front leg 41 is connected to a portion of the mounting bracket 5 that overlaps with the inner frame 221 in the vehicle fore-and-aft direction (when viewed from the vehicle width direction).

As shown in Figure 2, the rear leg 42 is connected to the first frame 23 so as to overlap with the first member 24 in the vehicle front-rear direction (as viewed in the vehicle width direction). For example, as shown in Figure 2, the rear end of the inner frame 231 of the first frame 23 is located further forward of the rear end of the outer frame 232, and as shown in Figures 3 and 4, the rear leg 42 is joined to the inner side surface of the outer frame 232 in the vehicle width direction behind the rear end of the inner frame 231.

5, the dimension H (height) of the front leg 41 and the rear leg 42 in the vehicle height direction is greater than the dimension W (width) in the vehicle front-rear direction. For example, the front leg 41 and the rear leg 42 include vertical walls 41a, 42a extending in the vehicle height direction, and a pair of horizontal walls 41b, 41c, 42b, 42c extending in the vehicle front-rear direction from the upper and lower ends of the vertical walls 41a, 42a, respectively. The dimension (height) of the vertical wall 41a (42a) is greater than the dimension (width) of the pair of horizontal walls 41b, 41c (42b, 42c).

For example, the pair of horizontal walls 41b, 41c of the front leg 41 extend rearward from the upper and lower ends of the vertical wall 41a, respectively, and the pair of horizontal walls 42b, 42c of the rear leg 42 extend forward from the upper and lower ends of the vertical wall 42a, respectively. That is, the front leg 41 is formed with a U-shaped cross section that opens toward the rear of the vehicle, and the rear leg 42 is formed with a U-shaped cross section that opens toward the front of the vehicle. The connection portion 43 is inserted into the openings of the front leg 41 and the rear leg 42 and joined to the front leg 41 and the rear leg 42, respectively, to connect the front leg 41 and the rear leg 42.

As shown in Figure 6, the cross member 4 has a support portion 431 for supporting the spare tire ST in the vehicle widthwise center portion of the cross member 4. The support portion 431 is provided, for example, in the connection portion 43. Note that the support portion 431 does not need to be located exactly in the center in the vehicle width direction. The vehicle widthwise center portion is a range having a width in the vehicle width direction that allows the spare tire ST to fit between a pair of side frames 2, 2.

According to the vehicle body frame 1 of the above embodiment, the cross member 4 is connected to each of the pair of side frames 2, 2 at two connection points spaced apart in the vehicle longitudinal direction, so that the width in the vehicle longitudinal direction at each connection point can be made smaller than that of a conventional cross member in which the pair of side frames 2, 2 are connected at one point. That is, the cross member needs to have a certain degree of strength and rigidity to cope with the twisting of the vehicle body, and one method of achieving this is to increase the width in the vehicle longitudinal direction. According to this embodiment, the desired strength and rigidity can be ensured by the sum of the widths in the vehicle longitudinal direction at the two connection points spaced apart in the vehicle longitudinal direction, so that the width in the vehicle longitudinal direction at each connection point can be made smaller than that of a conventional cross member in which the pair of side frames 2, 2 are connected at one point. In addition, the rear side of the cross member 4 is connected to the low strength region 2A, and the front side is connected to the high strength region 2B, so that the width in the vehicle longitudinal direction of the cross member 4 connected to the low strength region 2A can be made smaller than that of a conventional cross member. This reduces the amount of deformation inhibition of the low strength region 2A by the cross member 4 during a rear-end collision of the vehicle. Therefore, the collision energy during a rear-end collision is effectively absorbed by the low strength region 2A, improving the energy absorption performance during a rear-end collision. In addition, since the front side of the connection points is connected to the high strength region 2B, the load that twists the vehicle body input to the low rigidity region of the side frame 2 is transmitted to the front side of the vehicle through the rear side of the connection points and can be received by the high strength region 2B, ensuring the torsional rigidity of the vehicle.

In addition, the connection points at the rear of the vehicle overlap with the portion of the low-strength region 2A where the first member 24 is provided in the fore-and-aft direction of the vehicle, so that the portion of the low-strength region 2A where deformation is hindered in the fore-and-aft direction of the vehicle by the cross member 4 and the portion of the low-strength region 2A where deformation is hindered in the fore-and-aft direction of the vehicle by the first member 24 overlap in the fore-and-aft direction of the vehicle, making it possible to reduce the amount of deformation hindrance in the low-strength region 2A compared to when they are dispersed in the fore-and-aft direction of the vehicle.

In addition, when the first member 24 is a cab mount bracket 25, the connection point on the rear side of the vehicle overlaps with the cab mount bracket 25 in the fore-and-aft direction of the vehicle, so that the cross member 4 can suppress vibration of the cab mount bracket 25 and can also suppress vibration of the body (cabin) mounted on the cab mount bracket 25.

In addition, the connection points on the vehicle rear side are joined to the vehicle width direction inner surface of the outer frame 232, and the first member 24 is joined to the vehicle width direction outer surface of the outer frame 232, so that the connection points on the vehicle rear side can reinforce the location where the first member 24 of the outer frame 232 is attached.

In addition, because the dimension of the rear leg 42 in the vehicle height direction is greater than the dimension in the vehicle front-rear direction, the deformation strength in the vehicle height direction can be greater than the deformation strength in the vehicle front-rear direction. This makes it possible to make the rear leg 42 less susceptible to deformation in the vehicle up-down direction and easier to deform in the front-rear direction, so that the amount of deformation inhibition of the low-strength region 2A by the cross member 4 during a rear-end collision of the vehicle can be reduced while ensuring the torsional rigidity of the pair of side frames 2, 2.

In addition, the front leg 41 has a vertical wall 41a extending in the vehicle height direction and a pair of horizontal walls 41b, 41c extending from the upper and lower ends of the vertical wall 41a toward the rear of the vehicle, and the rear leg 42 has a vertical wall 42a and a pair of horizontal walls 42b, 42c extending from the upper and lower ends of the vertical wall 42a toward the front of the vehicle. In other words, the cross section of the front leg 41 opens toward the rear of the vehicle, and the cross section of the rear leg 42 opens toward the front of the vehicle, so that the deformation strength in the vehicle height direction can be made greater than the deformation strength in the vehicle longitudinal direction. In addition, since there are vertical walls at the front end of the front leg 41 and the rear end of the rear leg 42, there are vertical walls at both ends of the connection point between the side frame 2 and the cross member 4 in the vehicle longitudinal direction, and torsional rigidity can be ensured.

However, the method of making the deformation strength of the rear leg 42 in the vehicle height direction greater than the deformation strength in the vehicle front-rear direction is not limited to these. For example, the cross section of the rear leg 42 may be a closed cross section structure with dimensions in the vehicle height direction and the vehicle front-rear direction approximately equal, and a bead or recess extending in the vehicle height direction may be provided on the vertical wall facing the vehicle front-rear direction. Also, when the front leg 41 and the rear leg 42 are open cross sections, the cross section of the front leg 41 may open to the front of the vehicle and the cross section of the rear leg 42 may open to the rear of the vehicle, or the front leg 41 and the rear leg 42 may have an I-shaped cross section that opens on both sides in the vehicle front-rear direction.

In addition, by making the plate thickness of the first frame 23 thinner than that of the second frame 22, the deformation strength in the fore-and-aft direction of the vehicle is reduced, making it easy to provide the low-strength region 2A. In addition, the mounting bracket 5 is provided from the second frame 22 to the first frame 23 and connects the front leg 41 to the second frame 22, so that in the event of a rear-end collision, the side frame 2 is prevented from breaking at the connection portion between the second frame 22 and the first frame 23, and the low-strength region 2A can be deformed stably.

In addition, the cross member 4 has a generally X-shape in plan view, with the front legs 41 inclined from both outer sides in the vehicle width direction toward the rear of the vehicle inward, and the rear legs 42 inclined from both outer sides in the vehicle width direction toward the front of the vehicle inward. Therefore, for example, when the vehicle body twists, a load input to one side of the rear legs 42 in the vehicle width direction can be efficiently received by the other side of the front legs 41 in the vehicle width direction, thereby improving torsional rigidity.

In addition, because the spare tire ST is supported at the connection between the front legs 41, which incline toward the rear of the vehicle from both outside sides in the vehicle width direction toward the inside, and the rear legs 42, which incline toward the front of the vehicle from both outside sides in the vehicle width direction toward the inside, the cross member 4 can stably bear the load generated when the spare tire ST tries to move relative to the vehicle body. In this case, if the deformation strength of the rear legs 42 in the vehicle height direction is greater than the deformation strength in the vehicle fore-and-aft direction, the spare tire ST can be supported more stably.

The present invention is not limited to the above-described embodiment, but also includes modifications to the above-described embodiment and appropriate combinations of these embodiments. For example, the present invention is applicable not only to frame vehicles, but also to monocoque vehicles. Furthermore, the cross member 4 is not limited to being approximately X-shaped in plan view, but may be, for example, approximately H-shaped in plan view, with the front leg 41 and rear leg 42 extending straight in the vehicle width direction.

1 Vehicle body frame 2 Side frame 2A First region (low strength region)
2B Second area (high intensity area)
21 Frame 22 Second frame 221 Inner frame 222 Outer frame 23 First frame 231 Inner frame 232 Outer frame 24 First member 25 Cab mount bracket 26 Hook 3 Cross member 31, 32, 33, 34, 35, 36 Cross member 4 Cross member at rear end of vehicle 41 Front leg portion 42 Rear leg portion 43 Connection portion 431 Support portion 5 Mounting bracket ST Spare tire

Claims (9)

A pair of side frames provided at an interval in a vehicle width direction and extending along a front-rear direction of the vehicle;
A plurality of cross members are arranged at intervals in the vehicle front-rear direction and connect the pair of side frames to each other;
Equipped with
The pair of side frames have a first region provided in a rear portion of the vehicle across the vehicle front-rear direction, and a second region provided from a front end of the first region to a front side of the vehicle,
The first region is formed to have a smaller deformation strength in the vehicle front-rear direction than the second region,
Among the multiple cross members, the cross member arranged at the rearmost part of the vehicle has a front leg portion extending in the vehicle width direction and connected to the second region, a rear leg portion provided at a distance from the front leg portion toward the rear of the vehicle and extending in the vehicle width direction and connected to the first region, and a connection portion connecting the front leg portion and the rear leg portion at a center portion in the vehicle width direction.
Body frame. The side frame includes a first member protruding outward in a vehicle width direction in the first region,
The rear leg portion is joined to the side frame so as to overlap with the first member in the vehicle front-rear direction.
The vehicle body frame according to claim 1 . The first member is a cab mount bracket for mounting a body on the vehicle body frame.
The vehicle body frame according to claim 2 . The side frame includes an inner frame provided on an inner side in a vehicle width direction, and an outer frame provided on an outer side in the vehicle width direction and combined with the inner frame,
The rear leg portion is joined to an inner surface of the outer frame in a vehicle width direction,
The first member is joined to an outer surface of the outer frame in a vehicle width direction.
4. A vehicle body frame according to claim 2 or 3. The rear leg portion has a deformation strength in a vehicle height direction greater than a deformation strength in a vehicle front-rear direction.
A vehicle body frame according to any one of claims 1 to 4. The front leg portion and the rear leg portion are formed to have a U-shaped cross section that opens in the vehicle front-rear direction and includes a vertical wall extending in the vehicle height direction and a pair of horizontal walls extending in the vehicle front-rear direction from upper and lower ends of the vertical wall,
The front leg has a cross section that opens toward the rear of the vehicle,
The rear leg portion has a cross section that opens toward the front of the vehicle.
The vehicle body frame according to claim 5. the side frame includes a first frame provided in the first region and a second frame provided in the second region and connected to the first frame,
the first frame and the second frame are each formed of a folded plate-like body,
A plate thickness of the first frame is made thinner than a plate thickness of the second frame, so that a deformation strength in a vehicle front-rear direction of the first region is made smaller than that of the second region,
The front legs are connected to the pair of side frames via mounting brackets,
The mounting bracket is provided across the first frame and the second frame.
A vehicle body frame according to any one of claims 1 to 6. The front legs are inclined toward the rear of the vehicle from both outer sides toward the inside in the vehicle width direction, and the rear legs are inclined toward the front of the vehicle from both outer sides toward the inside in the vehicle width direction.
A vehicle body frame according to any one of claims 1 to 7. The vehicle body frame according to claim 8, wherein the connection portion has a support portion for supporting a spare tire.

Images