JP3939792B2 - ENERGY ABSORBING TUBE AND VEHICLE IMPACT ABSORBING DEVICE PROVIDED WITH THE ENERGY ABSORBING TUBE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an energy absorbing tube and an impact absorbing device including the same, and more particularly to an energy absorbing tube suitable for a vehicle impact absorbing device.
[0002]
[Prior art]
As a vehicle impact absorbing device, an impact absorbing steering device is known and widely used. This imparts energy absorbing characteristics to the steering device itself to alleviate the impact on the steering wheel, and devices of various structures are employed. For example, a ball-type shock-absorbing steering with a ball interposed between the outer column and inner column of the steering device, a mesh-type shock-absorbing steering using a metal mesh structure for the steering column, and silicon rubber sealed in the lower tube Silicon rubber-type shock absorbing steering and the like configured such that silicon rubber is ejected from the slit when the tube enters is used. Also, in a bumper support device for a vehicle, for example, a shock absorber unit in which a pipe body is filled with hydraulic pressure or silicon rubber is interposed between the bumper and the body.
[0003]
[Problems to be solved by the invention]
However, all of the above-described shock absorbing steering devices have a complicated structure. For example, in the case of ball-type shock absorbing steering, the inner column is stored in the outer column as it is when absorbing the shock. To do. Moreover, the weight is large and the cost is high. Further, the shock absorbing bumper support device described above also requires a storage stroke that is the same length as the absorption stroke as described above, has a complicated structure, is heavy, and is expensive.
[0004]
Accordingly, an object of the present invention is to provide an energy absorption tube that has a simple structure and is small, light, and inexpensive.
[0005]
Another object of the present invention is to provide a shock absorber for a vehicle to which a small, light and inexpensive energy absorbing tube is applied with a simple structure.
[0006]
[Means for Solving the Problems]
To achieve the above object, the energy absorbing tube of the present invention, as described in claim 1, to a metal tube to form a large diameter portion at one end of the tube body, large-diameter A portion where the tube diameter gradually decreases from the portion toward the other end of the tube, bends the inside of the large-diameter portion to form an overlapped portion where the bent portion expands outward, and the polymerization The tube diameter gradually decreases toward the one end side of the tubular body at a rate that is a gentler slope than the gradually decreasing rate of the tubular diameter of the overlapped portion in the large-diameter portion continuously to the portion, and is substantially the same diameter as the tubular body. A connecting portion that bends to the other end side of the tubular body is formed at the position.
[0008]
The energy absorption tube may be arranged in a steering device of a vehicle, and an impact on the steering device may be applied to both ends of the energy absorption tube to be absorbed.
[0009]
Further, the energy absorbing tube may be disposed in a bumper supporting device of a vehicle, and an impact on the bumper supporting device may be applied to both ends of the energy absorbing tube to be absorbed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention having the above configuration will be described with reference to the drawings. FIG. 1 shows a part of an energy absorption tube 1 according to an embodiment, and a large-diameter portion 3 (inner diameter Da) is formed on one end 1a side (lower side in FIG. 1) of a metal tube. A portion from the large-diameter portion 3 to the raw tube portion 2 (inner diameter Do, where Do <Da) of the tubular body is bent inside the large-diameter portion 3, and the bent portion 4 expands outward. Thus, the superposed part 5 is formed. Thus, the overlapping portion 5 is formed so that the tube diameter gradually decreases from the bent portion 4 toward the one end 1a side of the tubular body, and the gradually decreasing ratio of the tube diameter of the overlapping portion 5 continues to the overlapping portion 5. The pipe diameter gradually decreases toward the one end 1a side of the tube body at a different rate, for example, with a gentler gradient than the overlapping portion 5, and on the other end 1b side of the tube body at a position where the tube diameter is approximately the same as that of the raw tube portion 2. The connecting portion 6 is formed by bending. Thereby, in the large diameter part 3, the bending part 7 is formed between the raw pipe part 2 and the connection part 6 as shown in FIG.
[0011]
The energy absorption tube 1 having the above-described configuration can be manufactured by various methods. As one form, there is a manufacturing method including the steps shown in FIG. First, a metal base pipe Bp is arranged (A), and in the pipe expansion process B, the base pipe Bp is expanded by, for example, bulge forming. That is, the one end 1a side of the raw tube Bp is expanded to form the large diameter portion 3, and the tube diameter gradually decreases from the large diameter portion 3 toward the raw tube portion 2 on the other end 1b side of the raw tube Bp. The diameter is relatively reduced to form a reduced diameter portion 2c. In the bending step C, when the axial pressing force Po is applied to the open end of the raw tube portion 2 as indicated by an arrow in FIG. 4, the reduced diameter portion 2 c is placed inside the large diameter portion 3. The overlapping portion 5 is formed by bending, and the connecting portion 6 is formed toward the one end 1a. For example, as shown in an enlarged view in FIG. 5, the overlapping portion 5 is formed into a shape in which the bent portion 4 expands outward.
[0012]
In the pipe expansion step B, as shown in FIG. 9, if the inner diameter Dc of the portion of the raw pipe portion 2 continuous to the overlapping portion 5 is set to be larger than the inner diameter Do on the other end 1b side, In the bending process C, the bending operation is smoothly performed without applying a large load to the bent portion 4. That is, when the raw tube portion 2 is pressed by the pressing force Po and moves downward in FIG. 4, a component force is generated in the direction in which the tube is expanded with respect to the large diameter portion 3 (left and right direction in FIG. 9). For this reason, while the pressing force Po is appropriately distributed to the large diameter portion 3, the reduced diameter portion 2 c and the raw tube portion 2 are appropriately bent inside the large diameter portion 3.
[0013]
Thus, when the energy absorption tube 1 is formed as shown in FIG. 1 and the load Pd is applied in the axial direction in the normal state (N) shown on the left side of FIG. 3, the displacement-load shown in FIG. Deformation is performed according to the characteristics, and the state (D) shown on the right side of FIG. In other words, when the energy absorbing tube 1 is pressed in the axial direction, the generated load becomes substantially equal to the absorbing stroke immediately after the start of deformation, so that the energy is appropriately absorbed and a good shock absorbing ability is obtained. In addition, when the raw tube portion 2 is deformed, it is guided to the large diameter portion 3, so that predetermined deformation is reliably performed without bending during the deformation, and a stable shock absorbing structure is obtained. Further, in the present embodiment, since the tube portion 2 is supported in a stable state by the overlapping portion 5 when the tube portion 2 is deformed, the large-diameter portion 3 accompanying the deformation of the tube portion 2 even when the thickness of the tube body is thin. There is also no risk of causing deformation.
[0014]
FIG. 6 shows, as a comparative example with respect to the present embodiment, before and after deformation of a general tubular body having a uniform inner diameter, that is, a raw tube Bp. When the load Pd is applied in the axial direction of the raw tube Bp, the deformation is caused according to the displacement-load characteristic shown by the broken line in FIG. 2, and the bent portion Bpx shown on the right side of FIG. 6 is formed. Note that a straight line rising to the right indicated by a one-dot chain line in FIG. 2 is a displacement-load characteristic of an elastic member (not shown). In (N) and (D) of FIG. 3, each portion 1 a to 1 e of the energy absorption tube 1 indicates a portion corresponding to each other, the absorption stroke is represented by (k), and the storage stroke is represented by (s). . As can be seen from the figure, the storage stroke (s) is half of the absorption stroke (k) (s = k / 2), so the length of the large diameter portion 3 is made shorter than that of the conventional device. be able to.
[0015]
Next, an example in which the energy absorbing tube 1 in the above embodiment is applied to an impact absorbing device for a vehicle will be described with reference to the drawings. FIG. 7 shows an application of the energy absorption pipe 1 shown in FIG. 1 to a vehicle bumper support device. The bumper 10 is supported by the frame 20 via the energy absorption pipe 1. That is, the raw tube portion 2 is joined to the bumper 10, and the large diameter portion 3 is joined to the frame 20 via the brackets 11 and 12. Thus, when an impact force exceeding a predetermined limit is applied to the bumper 10, the energy absorbing tube 1 is deformed as described above, and the impact force is appropriately absorbed. The arrangement of the energy absorbing tube 1 may be reversed from that shown in FIG. 7, and other support structures may be employed instead of the brackets 11 and 12.
[0016]
FIG. 8 shows an application of the energy absorption tube 1 shown in FIG. 1 to a vehicle steering apparatus. A steering wheel 50 is connected to a steering mechanism (not shown) via a steering shaft 30 and a lower tube 40. . The steering shaft 30 is supported so as to be axially movable relative to the lower tube 40, and when an impact force exceeding a predetermined limit is applied to the steering wheel 50, the steering shaft 30 enters the lower tube 40. Is configured to do. The energy absorbing tube 1 is disposed so as to surround the steering shaft 30 and the lower tube 40, and the raw tube portion 2 is supported by a vehicle body (not shown) via a breakaway bracket 60. Further, the raw tube portion 2 is formed in a long shape, and the tip thereof is fixed to the steering shaft 30, and the tip of the large diameter portion 3 is fixed to the lower tube 40.
[0017]
Thus, when an impact force exceeding a predetermined limit is applied to the steering wheel 50, the steering shaft 30 enters the lower tube 40, and the energy absorption tube 1 is deformed as described above. Absorbed. The arrangement of the energy absorbing tube 1 may be reversed from that shown in FIG. 8, and further, silicon rubber is sealed in the lower tube 40 and silicon rubber is ejected from a slit (not shown) when the steering shaft 30 enters. May be. The energy absorbing tube of the present invention is not limited to the above-described vehicle shock absorbing device, and can be applied to shock absorbing structures in various fields.
[0018]
【The invention's effect】
Since this invention is comprised as mentioned above, there exists an effect as described below. In other words, the energy absorption tube of the present invention has a large diameter portion formed on one end side of a metal tube body, and the other end side of the tube body is one end of the tube body in the large diameter portion. So that the tube diameter gradually decreases toward one end of the tube and forms a connecting portion that bends to the other end of the tube at a position that is substantially the same diameter as the tube. Since it is configured, it is possible to appropriately absorb an impact force with a simple structure, and the shock absorption characteristic is always equal to the absorption stroke, resulting in an ideal shock absorption structure. In addition, since the storage stroke is half of the absorption stroke, it can be made compact. Furthermore, it can be configured to be lighter and less expensive than conventional products. In particular, a superposed portion in which the bent portion expands outward is formed, and the tubular body has a gentler slope than the gradually decreasing rate of the superposed portion in the large-diameter portion continuously from the superposed portion. The tube diameter gradually decreases toward one end of the tube, and a connecting part that is bent to the other end of the tube is formed at a position where the tube is approximately the same diameter as the tube, so even if the tube is thin There is no risk of causing deformation of the large-diameter portion at the time of bending, and the impact force can be absorbed appropriately.
[0020]
In addition, according to the vehicle steering device provided with the energy absorbing tube, the impact absorbing force to the steering device can be appropriately absorbed by the energy absorbing tube, and a small, lightweight and inexpensive shock absorbing device with a simple structure can be obtained. Can be provided.
[0021]
Further, according to the vehicle bumper support device provided with the energy absorption tube, the impact absorption force to the bumper support device can be appropriately absorbed by the energy absorption tube, and the impact absorption with a simple structure, small size, light weight and low cost. An apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view of an energy absorption tube according to an embodiment of the present invention.
FIG. 2 is a graph showing displacement-load characteristics of an energy absorption tube according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view showing before and after deformation of an energy absorption tube according to an embodiment of the present invention.
FIG. 4 is a process diagram showing a manufacturing process of an energy absorption tube according to an embodiment of the present invention.
FIG. 5 is an enlarged cross-sectional view of a superposed portion of an energy absorption tube according to an embodiment of the present invention.
FIG. 6 is a cross-sectional view showing before and after deformation of a general tubular body having a uniform inner diameter.
FIG. 7 is a cross-sectional view showing a state in which an energy absorption tube according to an embodiment of the present invention is applied to a vehicle bumper support device.
FIG. 8 is a cross-sectional view showing a state in which an energy absorption tube according to an embodiment of the present invention is applied to a vehicle steering device.
FIG. 9 is a cross-sectional view showing a part of the energy absorbing tube in another example of the expanding step of the energy absorbing tube according to the embodiment of the present invention.
[Explanation of symbols]
Bp Elementary pipe 1 Energy absorption pipe 2 Elementary pipe part 3 Large diameter part 4 Bending part 5 Superposition part 6 Coupling part 7 Bending part 10 Bumper 20 Frame 30 Steering shaft 40 Lower tube 50 Steering wheel

Claims (3)

For a metal tube, a large diameter portion is formed on one end side of the tube body, and a portion where the tube diameter gradually decreases from the large diameter portion toward the other end side of the tube body, Folded inward to form an overlapped portion where the bent portion expands outward, and in the large diameter portion continuous with the overlapped portion, a gentler slope than the gradually decreasing rate of the tube diameter of the overlapped portion An energy absorption tube formed by forming a connecting portion that gradually decreases toward the one end side of the tube body at a ratio and that bends to the other end side of the tube body at a position that is substantially the same diameter as the tube body. . The energy absorbing pipe according to claim 1, wherein arranged in the steering system of a vehicle, the impact vehicle you characterized by being configured to absorb by applying an impact to said steering device to both ends of the energy absorbing tube Absorber. The energy absorbing pipe according to claim 1, wherein arranged in the bumper support device for a vehicle, characterized in that the impact against the bumper support device and configured to absorb is applied to both ends of the energy absorbing tube vehicle Shock absorber.

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