JP2020104650A - Cross member for automobile - Google Patents

Abstract

To provide a cross member for automobile improved in the rigidity of a mount arm to make a tip portion of the mount arm less likely to be deformed when load is input from a wheel.SOLUTION: A cross member, to which support members for wheels are connected and which has a shape extending in a vehicle width direction, comprises: a mount section for the support members for the wheels disposed at both end of it; and a pair of mount arms. Each mount arm is composed of a hollow tube, a basal end portion of it is fixed to the cross member and a tip portion of it serves as a portion mounted on a vehicle body. The mount arm has, in a cross-section of a plane perpendicular to the axial direction of the hollow tube, a portion increasing in outside diameter in a direction orthogonal to a vehicle length direction with respect to outside diameter in the vehicle length direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cross member for an automobile.

When attaching wheels to the body of an automobile, a member called a cross member having a shape extending in the vehicle width direction is used. 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 place in the middle of the arm, and has a shape in which a tip portion faces the outer side in the vehicle width direction.

The above-mentioned arm has a shape in which the tip portion is formed by crushing a pipe, and has a through hole at the tip portion. When the chassis frame is attached to the vehicle body, the chassis frame is screwed to the vehicle body using the through hole at the tip portion. Both ends of the chassis frame of the cited document 1 have a structure in which wheels are supported via supporting members for the wheels.

Patent Document 2 describes a chassis frame including a pair of side members extending in the vehicle length direction and a rear cross member bridged between the side members. The end portion of the side member has a shape obtained by crushing a pipe, and has a through hole at its tip. When the chassis frame is attached to the vehicle body, the chassis frame is screwed to the vehicle body using the through hole at the tip portion. At both ends of the chassis frame of the cited document 2, the wheels are supported via support members for the wheels.

WO2012/147921A1 JP, 10-324269, A

The chassis frames of Patent Document 1 and Patent Document 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 traveling is input from the wheels. As described above, since the wheel frame supporting member is connected to the chassis frame, the steering characteristic changes each time the tip portion of the arm is displaced, which makes it difficult to exhibit the designed steering characteristic. is there.

An object of the present invention is to provide a cross member in which the rigidity of the mounting arm is increased and the tip 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 supporting member for a wheel is connected, wherein the cross member has a shape extending in the vehicle width direction, and includes a mounting portion for the supporting member for the wheel arranged at both ends thereof and a pair of mounting arms. The mounting arm comprises a hollow tube, a base end portion is fixed to the cross member, and a tip end portion is a mounting portion to a vehicle body. In the cross section of the plane perpendicular to the pipe axis direction of the empty pipe, the cross member for an automobile having a portion in which the outer diameter in the direction orthogonal to the vehicle length direction is larger than the outer diameter in the vehicle length direction is Solve the problem.

According to the above-mentioned automobile cross member, it is possible to increase the rigidity of the mounting arm. For example, when the load is input from the wheels during traveling of the automobile, the displacement amount of the tip portion of the mounting arm can be reduced. Will be possible. As a result, it is possible to prevent the handling characteristics from largely 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 a hollow pipe having a portion in which the outer diameter in the direction orthogonal to the vehicle length direction is larger than the outer diameter in the vehicle length direction, a shape having a first curved portion and a second curved portion By adopting, it becomes possible to balance the rigidity in the vehicle length direction, the vehicle width direction, and the vehicle height direction, and to exert 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 and the tip portion of the mounting arm is less likely to be displaced when a load is input from the wheel.

It is a perspective view showing a state where one embodiment of a cross member for vehicles is seen from the back side. It is the perspective view which showed the state which attached the vehicle cross member of FIG. 1 to the vehicle body from the front lower side of the vehicle body. It is a front view which shows the state of FIG. 2 seen from the front of the vehicle body. It is the rear view which expanded and showed a part of cross member for vehicles. It is sectional drawing in the AA part of FIG. 4 and FIG. It is the figure which expanded and showed the front-end|tip part of the attachment arm of the cross member for vehicles of FIG. It is explanatory drawing which shows the direction which applies a load to a mounting arm. 6 is a rear view showing an automobile cross member according to Test Example 2. FIG. It is sectional drawing in the BB part of FIG.

An embodiment of an automobile cross member 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 the present embodiment has a shape extending in the vehicle width direction, and a wheel supporting member (illustrated in the drawings) disposed at both ends thereof. (Not shown), and a pair of mounting arms 12.

The cross member 1 has a first convex portion 13 and a second convex portion 14 at the 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 has a shape recessed toward the center of the vehicle. The concave portion between the first convex portion 13 and the second convex portion 14 can be used as a space for accommodating the components of the suspension device. Similarly, the space between the left and right first protrusions 13, 13 and the space between the left and right second protrusions 14, 14 are also recessed. The concave portion between the left and right first convex portions 13 and 13 and the concave portion between the left and right second convex portions 14 and 14 can also be used as a space for accommodating other components. In the cross member 1, a first convex portion 13 having a mounting portion 11 for a support member for a wheel is arranged on the front side of the vehicle body, and a second convex portion 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. As shown in FIG. 1, the upper member 8 includes an upper plate 81 and a side wall 82 extending downward from an end portion of the upper plate 81. The lower member 9 includes a lower plate 91 and a side wall 92 extending upward from an end portion of the lower plate 91. The upper member 8 and the lower member 9 are joined by welding the side wall 82 of the upper member and the side wall 92 of the lower member. Therefore, the cross member 1 has a hollow structure and contributes to weight reduction of the vehicle body. The structure of the cross member is not limited to this, and may be any structure as long as the mounting arm and the support member of the wheel can be connected.

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

The first convex portion 13 of the cross member 1 is provided with a pair of support plates 111 as mounting portions 11 for supporting members of the wheel 6. The support plate 111 is provided with a through hole 112 for fixing a shaft extending along the front-rear direction of the vehicle body. The vehicle body shown in FIG. 2 employs a strut type suspension device. Therefore, the shaft of the base end portion of the lower arm (not shown) is connected to the through hole 112. The lower arm is swingable in the vertical direction of the vehicle body about the axis. 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 appropriately changed depending on the configuration of the wheel support member.

In the above example, the strut type suspension device is shown as an example. The supporting member for the wheel is not particularly limited, and examples thereof include a lower arm, a multi-link arm, a knuckle, a hub, a spring, a damper, and the like. The shape of the cross member is not particularly limited, and can be changed according to the layout of the members of the suspension device.

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 mounting parts to the vehicle body. The base end of the mounting arm has only to be fixed to the cross member 1, and its configuration is not particularly limited. In the cross member 1 of FIG. 1, the cross member 1 and the mounting arm 12 are fixed by welding in a state in which the base end portion thereof penetrates the upper plate 81 and the lower plate 91 of the cross member 1. In the cross member 1 of the present embodiment, the base end portion of the mounting arm 12 is connected to the support member of the wheel 6 near the mounting portion 11. The vicinity 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 supporting member is a connection portion to the vehicle body provided on the base end portion of the mounting arm 12 and the second convex portion 14. It is shorter than the straight line distance between.

The tip of the mounting arm may have any shape as long as the mounting arm can be fixed to the vehicle body, and the configuration thereof is not particularly limited. In the cross member 1 of FIG. 1, the tip has a shape obtained by clamping and crushing the tip of a pipe having a circular cross section, as shown in FIG. 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. At both ends of the flat portion 121, a spare portion 122 extending downward is arranged. The extra portion 122 is formed by bending a region to which pressure is not directly applied when the pipe is crushed and bent downward. The extra 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, the flat portion 121 of the mounting arm 12 is provided with a through hole 125. By screwing the through hole 125 and the through hole of the side frame 71 of the vehicle body in communication with each other, the mounting arm 12 is attached to the side frame 71 of the vehicle body 7 as shown in FIGS. 2 and 3. Fixed. The mounting 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 portion 12 can be stabilized by the flat portion 121 coming into contact with the member on the vehicle body side.

In the cross member 1 of the present embodiment, the base end of the mounting arm 12 is fixed to the cross member 1. Therefore, the load input to the cross member 1 via the wheel 6 and the wheel supporting 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 members of the wheels connected thereto are largely displaced depending on the input load. That is, when the mounting arm is displaced, the positions of the wheels are also changed, and the predesigned handling characteristics are disturbed.

When the vehicle is traveling, 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 is often applied 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. 4, the first bending portion 123 and the second bending portion 124 are viewed from the viewpoint along the vehicle length direction. It has a shape having and. 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 tip end portion and the base end portion of the mounting arm 12. As shown in FIG. 5, the shape of the mounting arm 12 has an outer shape B in a direction orthogonal to the vehicle length direction with respect to an outer diameter A in the vehicle length direction when a cross section of the mounting arm 12 is taken. Has a larger part. The cross section means a cross section of a plane perpendicular to the tube axis 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 increases with respect to 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 is the front-back direction of the vehicle body. In the cross member 1 of this embodiment, since the round pipe is used, the portion where the outer diameter B is larger than the outer diameter A is the elliptical outer diameter where the outer diameter is large. The shape of the portion may be, for example, a rectangular shape.

By configuring the mounting arm as described above, the amount of displacement of the mounting arm in the vehicle length direction, the vehicle width direction, and the vehicle body height direction can be reduced in a well-balanced manner. The position where the portion where the outer diameter B is larger than the outer diameter A is provided is not particularly limited, but 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 the present embodiment, the mounting arm 12 projects from the upper surface of the cross member 1 in the height direction of the vehicle body, and is bent outward by the first curved portion 123 and the second curved portion 124 in the vehicle width direction. The tip portion thereof has a shape protruding 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 and the tip of the mounting arm 12 is not particularly limited, but is preferably 60 to 130°, for example. The mounting arm is bent by the first curved portion 123 and the second curved portion 124, and the protruding direction is not limited to the outer side in the vehicle width direction, and may be the vehicle length direction or the like.

The mounting arm 12 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 crushing the tip of the pipe and bending both ends of the tip. When the pipe is bent by a single bending process, the constituent material of the pipe is compressed inside the radius and the constituent material of the pipe is pulled outside the radius. By bending the pipe at a plurality of locations, it is possible to reduce deterioration in rigidity of the pipe due to tension or compression. In addition, in a hollow pipe having a portion in which the outer diameter in the direction orthogonal to the vehicle length direction is larger than the outer diameter in the vehicle length direction, a hollow pipe having a shape including a first curved portion 123 and a second curved portion 124 By adopting this, it becomes possible to balance the rigidity in the vehicle length direction, the vehicle width direction, and the vehicle height direction, and to exert the rigidity against loads from various directions.

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

[Test Example 1]
As shown in FIG. 7, two points at the base end of the mounting arm 12 used for the cross member of FIGS. 1 to 6 are completely restrained as shown in FIG. A load of 1000 N was applied in each of the Z direction and the Z direction, and how much the M point was displaced was examined based on the state before the load was applied. This is designated as Test Example 1. The shape of the mounting arm used in Test Example 1 is the same as the shape of the mounting arm in FIGS. 4 and 5. 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, and the mounting arm has a transverse sectional shape with respect to an outer diameter in the vehicle length direction. , Has a portion having a large outer diameter in a direction orthogonal to the vehicle length direction. 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 body height direction.

[Test Examples 2 to 3]
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. , The X direction, the Y direction, or the displacement amount in the Z direction was examined. As shown in FIGS. 8 and 9, the mounting arm 42 has a perfect circular cross section at the portion B, and the angle formed between the base end portion and the tip end portion is 90° by one bending process. The shape is bent so that 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.

Although the mounting arm according to Test Example 3 includes the first curved portion and the second curved portion, as in the case shown in FIG. 4, the cross-sectional shape corresponding to the portion A in FIG. 4 is a perfect circle. .. The mounting arm according to Test Example 4 has a cross-sectional shape corresponding to the cross section of the portion A in FIG. 4 that is an elliptical shape similar to that in FIG. 5, and, as in the case shown in FIG. The shape is bent so that the angle formed by the portion and the tip portion is 90°. That is, the mounting arm of Test Example 4 has a shape in which the outer diameter of the hollow pipe in the direction orthogonal to the vehicle length direction is larger than the outer diameter of the hollow pipe in the vehicle length direction. The shape does not include a curved portion.

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

As shown in Table 1, the mounting arm is composed of a hollow pipe having a first curved portion and a second curved portion, and the mounting arm has a transverse cross-sectional shape with respect to an outer diameter in the vehicle longitudinal direction. It can be seen that in the mounting arm according to Test Example 1 having the portion where the outer diameter in the direction orthogonal to the longitudinal direction is large, the rigidity in the vehicle height direction (Z direction) is significantly improved. The rigidity in the vehicle length direction (X direction) and the vehicle width direction (Y direction) is also balanced. Further, as is clear from the comparison between Test Example 4 and Test Example 1, the reduction in rigidity in the vehicle length direction (X direction) due to the hollow tube being crushed in the vehicle length direction (elliptical shape) It can be seen that is compensated by adopting the shape having the first curved portion and the second curved portion.

DESCRIPTION OF SYMBOLS 1 Automobile cross member 12 Mounting arm 11 Mounting portion for a wheel supporting member 123 First curved portion 124 Second curved portion

Claims (2)

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 of a wheel supporting member arranged at both ends thereof, and a pair of mounting arms.
The mounting arm is composed of a hollow tube, the base end is fixed to the cross member, the tip is a mounting portion to the vehicle body,
The vehicle having a portion in which the mounting arm has a larger outer diameter in a direction orthogonal to the vehicle length direction than an outer diameter in the vehicle length direction in a cross section of a plane perpendicular to the pipe axis direction of the hollow pipe. For cross member. The automobile cross member according to claim 1, wherein the mounting arm is formed of a hollow tube having a first curved portion and a second curved portion.

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