JP7164871B2 - automotive cross member - Google Patents

Description

The present invention relates to cross members for motor vehicles.

A member having a shape extending in the vehicle width direction called a cross member is used when a wheel is attached to the vehicle body of an automobile. For example, Patent Document 1 has a chassis frame having a shape extending in the vehicle width direction and a pair of curved arms provided at the left and right ends of the chassis frame. The arm protrudes upward from the chassis frame, is curved at one point in the middle of the arm, and has a shape in which the distal end faces outward in the vehicle width direction.

The tip portion of the arm has a shape of a crushed pipe, and the tip portion has a through hole. When attaching the chassis frame to the vehicle body, the chassis frame is screwed to the vehicle body using the through holes at the tip portion. Both ends of the chassis frame of Cited Document 1 have a structure in which wheels are supported via support members for the wheels.

Patent Document 2 describes a chassis frame including a pair of side members extending in the longitudinal direction of the vehicle and a rear cross member bridged between the side members. The end of the side member is shaped like a crushed pipe, and has a through hole at the tip. When attaching the chassis frame to the vehicle body, the chassis frame is screwed to the vehicle body using the through holes at the tip portion. Both ends of the chassis frame of Cited Document 2 have a structure in which wheels are supported via support members for the wheels.

WO2012/147921A1 publication JP-A-10-324269

The chassis frames of Patent Documents 1 and 2 have a structure in which the wheels are attached to the vehicle body via the chassis frame. In these chassis frames, the chassis frame is attached to the vehicle body by fixing the distal end portion of the tubular arm to the vehicle body. If the rigidity of the arm is low, the tip portion of the arm will be displaced together with the chassis frame when a load during running is input from the wheels. As mentioned above, the wheel support members are connected to the chassis frame, so the steering characteristics change each time the tip of the arm is displaced, making it difficult to achieve the designed steering characteristics. be.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cross member in which the rigidity of a mounting arm is increased so that the distal end portion of the mounting arm is less likely to be displaced when a load is input from a wheel.

A cross member to which a wheel support member is connected, wherein the cross member has a shape extending in the vehicle width direction, and includes mounting portions for the wheel support member arranged at both ends thereof and a pair of mounting arms. The mounting arm is composed of a hollow tube, has a proximal end fixed to the cross member, and a distal end serving as a mounting portion to the vehicle body. The cross member for automobiles having a portion in which the outer diameter in the direction perpendicular to the vehicle length direction is larger than the outer diameter in the vehicle length direction in the cross section of the plane perpendicular to the tube axis direction of the empty tube, solve the problem.

According to the automobile cross member described above, it is possible to increase the rigidity of the mounting arm. For example, when a load is input from the wheel while the automobile is running, the amount of displacement of the tip portion of the mounting arm can be reduced. becomes possible. As a result, it is possible to prevent the handling characteristics from significantly changing when a load is input from the wheels.

In the automobile cross member described above, it is preferable that the mounting arm is formed of a hollow tube having a first curved portion and a second curved portion. As described above, in the hollow pipe having a portion in which the outer diameter in the direction perpendicular to the vehicle length direction is larger than the outer diameter in the vehicle length direction, the shape having the first curved portion and the second curved portion By adopting , it is possible to balance the rigidity in the vehicle length direction, the vehicle width direction, and the vehicle height direction, and exhibit the rigidity against loads from various directions.

According to the present invention, it is possible to provide a cross member in which the rigidity of the mounting arm is increased so that the distal end portion of the mounting arm is less likely to be displaced when a load is input from the wheel.

1 is a perspective view showing an embodiment of a cross member for an automobile as seen from the back side; FIG. FIG. 2 is a perspective view showing a state in which the automobile cross member of FIG. 1 is attached to the vehicle body, viewed from the lower front side of the vehicle body; FIG. 3 is a front view showing the state of FIG. 2 as viewed from the front of the vehicle body; FIG. 2 is a rear view showing an enlarged part of the automobile cross member. FIG. 7 is a cross-sectional view taken along line AA of FIGS. 4 and 6; FIG. 2 is an enlarged view of a tip portion of a mounting arm of the automobile cross member of FIG. 1; It is an explanatory view showing the direction in which a load is applied to the mounting arm. FIG. 11 is a rear view showing an automobile cross member according to Test Example 2; FIG. 9 is a cross-sectional view of the BB portion of FIG. 8;

One embodiment of a cross member for automobiles will be described with reference to the drawings.

As shown in FIG. 1, an automobile cross member 1 (hereinafter referred to as a cross member) of this embodiment has a shape extending in the vehicle width direction, and wheel support members (illustrated ) and a pair of mounting arms 12 .

The cross member 1 has a first protrusion 13 and a second protrusion 14 at its left and right ends. A space between the first convex portion 13 and the second convex portion 14 on each of the left and right sides is recessed toward the center of the vehicle. A concave portion between the first convex portion 13 and the second convex portion 14 can be used as a space for housing components of the suspension system. Similarly, between the left and right first convex portions 13, 13 and between the left and right second convex portions 14, 14 are also recessed. The recesses between the left and right first protrusions 13, 13 and the recesses between the left and right second protrusions 14, 14 can also be used as spaces for accommodating other parts. In the cross member 1, a first protrusion 13 having a mounting portion 11 for a wheel support member is arranged on the front side of the vehicle body, and a second protrusion 14 is arranged on the rear side of the vehicle body.

The cross member 1 is a hollow horizontally long member and includes an upper member and a lower member. The upper member 8 includes a top plate 81 and sidewalls 82 extending downward from the ends of the top plate 81, as shown in FIG. The lower member 9 includes a lower plate 91 and sidewalls 92 extending upward from ends of the lower plate 91 . The upper member 8 and the lower member 9 are joined by welding side walls 82 of the upper member and side walls 92 of the lower member. Therefore, the cross member 1 has a hollow structure, which contributes to weight reduction of the vehicle body. The structure of the cross member is not limited to this, as long as it can connect the mounting arm and the wheel support member.

As shown in FIG. 2 , the left and right second projections 14 of the cross member 1 are screwed to the side frames 71 of the vehicle body 7 . More specifically, a through hole is arranged at the tip portion of the second protrusion 14 . A screw is inserted so as to communicate with the through hole of the second projection 14 and the through hole of the side frame of the vehicle body 7 and screwed. The side frame 71 has a shape bent in two steps in the vehicle length direction, and the bent shape is used to form a space for accommodating the suspension system. The mounting arm 1 of the cross member 1 is fixed to the side frame 71 at a high position, and the second projection 14 is fixed to the side frame 71 at a low position. The side frame 71 of the vehicle body and the second protrusion 14 may be fixed to each other by welding. The configuration for connecting the cross member 1 to the member on the vehicle body side is not limited to the second protrusion 14, and the second protrusion may be omitted. A cross member 1 shown in FIG. 2 is an example of a front cross member fixed to the front wheel side of a vehicle body. The cross member may be a rear cross member fixed to the rear wheel side of the vehicle body.

The first projection 13 of the cross member 1 is provided with a pair of support plates 111 as mounting portions 11 for supporting members of the wheels 6 . The support plate 111 is provided with a through hole 112 for fixing a shaft extending in the longitudinal direction of the vehicle body. The vehicle body shown in FIG. 2 employs a strut-type suspension system. For this reason, the through hole 112 is connected to the shaft of the base end of the lower arm (not shown). The lower arm is in a state capable of swinging in the vertical direction of the vehicle body about the shaft. A knuckle (not shown) is connected to the tip of the lower arm. A hub (not shown) is connected to the knuckle. The configuration of the attachment portion of the wheel support member is not limited to this, and can be changed as appropriate depending on the configuration of the wheel support member.

In the above example, a strut-type suspension system is shown as an example. The wheel support member is not particularly limited, but includes a lower arm, a multi-link arm, a knuckle, a hub, a spring, or a damper. The shape of the cross member is also not particularly limited, and can be changed according to the layout of the members of the suspension system.

As shown in FIG. 1, the base ends of the pair of mounting arms 12 are fixed to the cross member 1, and the tip ends of the mounting arms 12 are mounted to the vehicle body. The base end portion of the mounting arm is not particularly limited as long as it is fixed to the cross member 1 . In the cross member 1 shown in FIG. 1, the cross member 1 and the mounting arm 12 are fixed by welding in a state in which the base end of the cross member 1 passes through the upper plate 81 and the lower plate 91 of the cross member 1. As shown in FIG. In the cross member 1 of this embodiment, the base end portion of the mounting arm 12 is connected to the mounting portion 11 side of the support member of the wheel 6 . The nearness of the mounting portion 11 means that the linear distance between the base end portion of the mounting arm 12 and the mounting portion 11 of the wheel support member is the connection portion to the vehicle body provided at the base end portion of the mounting arm 12 and the second convex portion 14. Shorter than the straight line distance between

The shape of the tip portion of the mounting arm is not particularly limited as long as the shape is such that the mounting arm can be fixed to the vehicle body. As shown in FIG. 6, the cross member 1 shown in FIG. 1 has a shape obtained by clamping and crushing the tip of a pipe having a circular cross section. A flat portion 121 is formed in the middle of the tip portion, and the flat portion 121 has a shape extending in a substantially horizontal direction. Both ends of the flat portion 121 are shaped to have surplus portions 122 extending downward. The surplus portion 122 is formed by bending downward a region where pressure is not applied directly when the pipe is crushed. The surplus portion 122 functions as a reinforcing portion that improves the rigidity of the tip portion of the pipe. The pipe may be a square pipe.

As shown in FIG. 1, a through hole 125 is arranged in the flat portion 121 of the mounting arm 12 . The mounting arm 12 is attached to the side frame 71 of the vehicle body 7 as shown in FIGS. Fixed. The attachment arm 12 and the vehicle body 7 may be fixed by welding instead of screwing. By providing the flat portion 121 at the tip of the mounting arm 12, the mounting arm 12 can be stabilized by contacting the flat portion 121 with a member on the vehicle body side.

In the cross member 1 of this embodiment, the base ends of the mounting arms 12 are fixed to the cross member 1 . Therefore, the load input to the cross member 1 via the wheel 6 and the wheel support member is transmitted to the mounting arm 12 . If the rigidity of the mounting arm 12 is not sufficient, the positions of the cross member 1 and the supporting member of the wheel connected thereto will be displaced greatly according to the input load. In other words, when the mounting arm is displaced, the position of the wheel is also changed, which disturbs the pre-designed handling characteristics.

When the vehicle is running, a load is input to the cross member via the wheels due to unevenness of the road surface, acceleration of the vehicle, deceleration of the vehicle, turning motion of the vehicle, or the like. In particular, a large load often acts in the height direction of the vehicle, and if the rigidity of the mounting arm 12 is insufficient in the height direction, the handling characteristics are significantly affected.

In the cross member 1 of the present embodiment, the mounting arm 12 is composed of a hollow tube, and as shown in FIG. and has a shape. By constructing the mounting arm from a hollow tube, it is possible to contribute to weight reduction of the vehicle body. The first curved portion 123 and the second curved portion 124 are arranged between the distal end portion and the proximal end portion of the mounting arm 12 . As shown in FIG. 5, the shape of the mounting arm 12 is such that when the cross section of the mounting arm 12 is taken, the outer diameter A in the vehicle length direction is compared to the outer shape B has a larger portion. A cross section refers to a cross section of a plane perpendicular to the axial direction of the hollow tube. That is, since the mounting arm 12 is arranged so that the direction in which the outer diameter of the hollow tube increases is aligned with the direction in which the load for bending the mounting arm 12 is input, the section modulus of the hollow tube increases. . In this specification, the vehicle length direction means the longitudinal direction of the vehicle body. Since the cross member 1 of this embodiment uses a round pipe, the portion where the outer diameter B is larger than the outer diameter A is the portion where the outer diameter of the ellipse is larger. The shape of the portion may be, for example, a rectangular shape.

By shaping the mounting arm as described above, the amount of displacement of the mounting arm in the vehicle length direction, vehicle width direction, and vehicle height direction can be reduced in a well-balanced manner. Although the position where the portion where the outer diameter B is larger than the outer diameter A is provided is not particularly limited, it is preferably provided continuously between the first curved portion 123 and the second curved portion 124, for example.

In the cross member 1 of this embodiment, the mounting arm 12 protrudes from the upper surface of the cross member 1 in the height direction of the vehicle body, and is bent outward in the vehicle width direction by the first curved portion 123 and the second curved portion 124, It has a shape in which the tip protrudes substantially horizontally. The place where the mounting arm is provided is not particularly limited, but it is preferably provided on the upper surface of the cross member. The angle formed by the base end portion and the tip end portion of the mounting arm 12 is not particularly limited, but is preferably 60 to 130°, for example. The direction in which the mounting arm is bent by the first curved portion 123 and the second curved portion 124 and protrudes is not limited to the outside in the vehicle width direction, and may be in the vehicle length direction or the like.

The mounting arm 12 described above can be manufactured, for example, by bending a pipe having a circular cross section a plurality of times. The tip of the mounting arm 12 can be formed by clamping and squeezing the tip of the pipe and bending the ends of the tip. When the pipe is bent in a single bending process, the constituent materials of the pipe are compressed inside the radius and the constituent materials of the pipe are stretched outside the radius. By bending the pipe at a plurality of points, it is possible to reduce the decrease in rigidity of the pipe due to tension or compression. Further, in the hollow pipe having a portion in which the outer diameter in the direction perpendicular to the vehicle length direction is larger than the outer diameter in the vehicle length direction, a shape having the first curved portion 123 and the second curved portion 124 is used. By adopting it, it becomes possible to balance the rigidity in the vehicle length direction, the vehicle width direction, and the vehicle height direction, and exhibit the rigidity against loads from various directions.

The material of construction of the mounting arm or cross member is not particularly limited, but metal such as carbon steel, for example, can be used.

[Test Example 1]
The two points at the proximal end of the mounting arm 12 used in the cross members of FIGS. 1-6 are fully constrained as shown in FIG. A load of 1000 N was applied in each direction and Z direction, and how much the point M was displaced was examined based on the state before the load was applied. This is referred to as Test Example 1. The shape of the mounting arm used in Test Example 1 is identical to that of FIGS. That is, the mounting arm of Test Example 1 is composed of a hollow tube having a first curved portion and a second curved portion. , has a portion where the outer diameter in the direction orthogonal to the vehicle length direction is large. The X direction corresponds to the vehicle length direction of the vehicle body, the Y direction corresponds to the vehicle width direction, and the Z direction corresponds to the vehicle height direction.

[Test Examples 2 to 4 ]
For comparison, the mounting arm 42 according to Test Example 2, the mounting arm according to Test Example 3, and the mounting arm according to Test Example 4 shown in FIGS. 8 and 9 were also loaded under the same conditions. , X direction, Y direction, or Z direction. As shown in FIGS. 8 and 9, the mounting arm 42 of Test Example 2 has a perfect circular cross-sectional shape at the B portion. is bent at an angle of 90°. That is, the mounting arm 42 of Test Example 2 has a shape that does not include the first curved portion and the second curved portion.

The mounting arm according to Test Example 3 has a first curved portion and a second curved portion in the same manner as shown in FIG. 4, but has a perfect circular cross-sectional shape corresponding to part A in FIG. . The mounting arm according to Test Example 4 has an elliptical cross-sectional shape corresponding to the cross-section of portion A in FIG. 4 similar to that in FIG. It is bent so that the angle between the tip and the tip is 90°. That is, the mounting arm of Test Example 4 has a shape in which the outer diameter in the direction perpendicular to the vehicle length direction is larger than the outer diameter of the hollow pipe in the vehicle length direction. It is a shape that does not have a curved portion.

Table 1 summarizes the displacement results. In Table 1, with the displacement amount of Test Example 2 as the reference (100%), the rate of increase or decrease in each displacement amount in the X direction, Y direction, or Z direction for Test Examples 1, 3, and 4 is shown. Expressed as a percentage.

As shown in Table 1, the mounting arm is composed of a hollow tube having a first curved portion and a second curved portion. It can be seen that the mounting arm according to Test Example 1, which has a portion with a larger outer diameter in the direction orthogonal to the longitudinal direction, has significantly improved rigidity in the height direction (Z direction) of the vehicle. Rigidity in the vehicle length direction (X direction) and vehicle width direction (Y direction) is also well balanced. Further, as is clear from the comparison between Test Example 4 and Test Example 1, the rigidity in the vehicle length direction (X direction) decreased due to the shape (ellipse) of the hollow tube that was crushed in the vehicle length direction. is compensated for by adopting a shape having a first curved portion and a second curved portion.

1 Automobile cross member 12 Mounting arm 11 Mounting portion 123 for supporting member of wheel 1st curved portion 124 Second curved portion

Claims (1)

A cross member to which a wheel support member is connected,
The cross member has a shape extending in the vehicle width direction, and has a mounting portion for a wheel support member arranged at both ends thereof, and a pair of mounting arms,
The mounting arm is composed of a hollow tube, has a proximal end fixed to the cross member, and a distal end serving as a mounting portion to the vehicle body,
The mounting arm has a portion in which the outer diameter in the direction perpendicular to the vehicle length direction is larger than the outer diameter in the vehicle length direction in a plane cross section perpendicular to the tube axis direction of the hollow tube. and
A cross member for an automobile, wherein the mounting arm comprises a hollow tube having a first curved portion and a second curved portion.

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