JP2001090763A - Striking energy absorbing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce weight of a striking energy absorbing device, and to stabilize/increase stable breaking stress. SOLUTION: In a striking energy absorbing device 1 having a cylindrical striking energy absorbing member 2 and a trigger 3 and having the trigger 3 having an inserting part 4 fitted to an opening part on one end of the cylindrical member 2 and an expansive width part 5 being integrally molded with the inserting part and having a diameter being larger than a diameter of the inserting part and becoming large as a distance separates from the inserting part, the trigger 3 is hollow and is made of resin, and a recess/projection is arranged at least in a part of either one surface of mutually contacting surfaces of the trigger 3 and the cylindrical member 2. The trigger 3 can have a rib 8 extending in the axial direction on the inside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact energy absorbing device applied to, for example, a steering column and a steering shaft of a vehicle steering apparatus, or a propeller shaft, a bumper stay, an instrument panel column, a shift lever, and the like.

[0002]

2. Description of the Related Art Heretofore, there has been known an impact energy absorbing device in which a trigger (crush element) is provided at one end of a cylindrical impact energy absorbing member. This device is sandwiched between parts such as a car that may receive an impact, and when an impact load is applied from one of the parts, the trigger enters the inside of the shock energy absorbing member and the trigger To reduce the impact load transmitted to the other component. As an example of such an impact energy absorbing device, see JP-A-10-30669.
The publication discloses a shock-absorbing member made of a fiber-reinforced plastic having a cylindrical shape, an insertion portion to be inserted into an opening at one end of the member, and a diameter which is concentric with the insertion portion and concentric with the insertion portion. A metal trigger having a widened portion is described.

The basic characteristics required of an impact energy absorbing device include: 1) stable destruction of an impact energy absorbing member. 2) The specific shape and precision of the part. For example, the shape and dimensional accuracy of the widened portion (also referred to as a curved portion or R portion) of the trigger that comes into contact with the cylindrical impact energy absorbing member when the member is broken. 3) Since the trigger needs to maintain its shape even when a stress (load) is applied to break the impact energy absorbing member, the trigger itself must not be deformed. And the like.

In order to satisfy the above requirements, a high-precision die-casting method using a highly rigid metal (aluminum or zinc) is used for molding the trigger. However, the trigger made of metal is naturally heavy, and this poses a problem particularly when the weight of a vehicle to which the trigger is applied is reduced. In addition, metal products have a limited degree of freedom in design.

Furthermore, the R portion of the conventional trigger and the inner surface of the cylindrical impact energy absorbing member are smooth, and the utilization of frictional stress between the trigger and the cylindrical member has been insufficient. Therefore, when the trigger enters the tubular member, the trigger slips with respect to the member, and the trigger does not often advance stably.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an impact energy absorbing device having a cylindrical impact energy absorbing member and a metal trigger, which is lightweight and has stable and increased stable fracture stress. It is. Note that the stable fracture stress is a fracture stress that continues to be generated with a relatively constant strength immediately after the initial fracture stress generated immediately after an impact is applied to the device until the end of the destruction.

[0007]

The object of the present invention is to provide a structure in which a trigger is made of resin and has a hollow structure, and irregularities are provided on one of the surfaces of the trigger and the cylindrical impact energy absorbing member which are in contact with each other. Achieved.

That is, the impact energy absorbing device of the present invention is a shock energy absorbing device having a cylindrical impact energy absorbing member and a trigger, and the trigger is fitted into an opening at one end of the tubular member. An impact energy absorbing device comprising: an insertion portion having a diameter; and a widened portion integrally formed with the insertion portion and having a diameter larger than the diameter of the insertion portion and having a larger diameter as the distance from the insertion portion increases. The trigger and the cylindrical impact energy absorbing member are provided with irregularities on at least a part of at least one of the surfaces that are in contact with each other.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the impact energy absorbing device of the present invention, and FIG. 2 is a sectional view of the device.

As shown in FIGS. 1 and 2, the cylindrical impact energy absorbing member 2 which is the main member of the impact energy absorbing device 1 of the present invention is usually cylindrical. This tubular member is a member that breaks to absorb impact energy, and is preferably made of resin from the viewpoint of weight reduction.

The cylindrical impact energy absorbing member 2 shown in the figure mainly has a function of breaking and deforming itself while absorbing the compressive stress applied in the axial direction.
The trigger 3 stabilizes the pattern of the strain applied to the impact energy absorbing member 2 by the stress in terms of energy absorption efficiency. The impact energy absorbing member 2 preferably causes delamination as shown in FIG. By this delamination, it is possible to suppress accumulation of excessive strain in the curved wall of the member 2 and to consume energy due to frictional resistance generated between the delaminated layers. Examples of the impact energy absorbing member 2 that performs such delamination include those manufactured by laminating a plurality of uncured thermosetting resin sheets (prepregs) containing reinforcing fibers and curing the laminated sheets. And those manufactured by injection molding while controlling the orientation of a thermoplastic resin having a strong orientation.

As described above, examples of the method of manufacturing the cylindrical impact energy absorbing member include injection molding of a thermoplastic resin and a method using fiber reinforced plastic (FRP). In the case of a method using FRP as a material, for example, a prepreg obtained by impregnating a thermosetting resin such as an unsaturated polyester resin or an epoxy resin into a glass fiber base cloth or a carbon fiber base cloth is wound around a mandrel (metal cylinder) to form a cylinder. Forming
This is cured by heating. After curing, the resin cylindrical body can be obtained by passing through the mandrel.

On the other hand, as a method for manufacturing a cylindrical impact energy absorbing member using a thermoplastic resin, for example, a method using a thermotropic liquid crystal polymer is disclosed in
The method proposed in JP-A-11-13806 can be employed. That is, this is achieved by using a thermotropic liquid crystal polymer, for example, a thermotropic liquid crystal polyester, as the resin to be injection-molded, and injecting this resin into a cavity formed by the inner core and the outer mold, and simultaneously rotating the inner core to form the cylinder. This is an injection molding method of a rotary core type for molding a cylindrical member.

Next, a trigger 3 for crushing the cylindrical impact energy absorbing member 2 is provided with an insertion portion 4 and a widened portion 5 as shown in a cross section in FIG. 6 may be provided. The insertion portion 4 of the trigger is a cylinder having an outer diameter substantially equal to the inner diameter of the tubular member 2 and is fitted into an opening at one end of the tubular member 2 before an impact is applied in the axial direction (FIG. 2 (a)). On the other hand, the widening portion 5 is outside the tubular member 2 before the impact is applied (FIGS. 1 and 2 (a)), and the diameter of the widening portion 5 is larger than the diameter of the insertion portion 4 and separates from the insertion portion. And continuously increases. The change in the diameter of the widened portion 5 is not limited to the linear taper shape shown in FIG.
It may be curved as shown in FIG.

The impact energy absorbing device 1 of the present invention
As shown in FIG. 2, when an impact is applied in the axial direction as shown in FIG. 2, the widened portion 5 of the trigger 3 enters the hollow interior of the tubular member 2 to break the member 2, thereby absorbing the impact energy.

The trigger is required to have fitting accuracy and shape retention in order to fulfill the above-mentioned functions. So, in general,
Manufactured from metal with good shape accuracy and stiffness, this ultimately makes the overall shock energy absorbing device bulky. This problem can be solved by replacing the metal trigger with a resin and one with a hollow structure.However, the trigger obtained by hollow molding for manufacturing a general hollow structure molded product has a fitting accuracy and rigidity. It is not enough on both sides.

Further, the impact energy absorbing member is disclosed in JP-A-11-13806, JP-A-11-13807, JP-A-11-13807.
1-82588, JP-A-11-182604, and the like, when a mold member forming an inner surface of an impact energy absorbing member is manufactured by an injection molding apparatus that rotates in a circumferential direction, a trigger of the obtained absorbing member is obtained. Since the inner surface in contact with the trigger is smooth, the amount of impact energy consumed by the resistance related to the "friction" with the trigger shown in FIG. 2 tends to be small. Further, in an impact energy absorbing member made of an oriented liquid crystal polymer described in the patent publication,
The broken wall pushed outward in the outer peripheral direction by the trigger does not cause minute cracks and breakage unlike the wall of the thermosetting resin impact energy absorbing member, so it is involved in "friction" between the trigger and the wall The amount of energy consumed by the resistance tends to be small.

It is possible to increase the resistance to "friction" by providing the metal trigger with irregularities on the side surface of the widened portion by a known method. However, the method of providing the unevenness generally has a problem that a complicated process is required. In particular, it is difficult to form unevenness evenly on the curved side surface.

However, if the trigger 3 is formed of a resin as in the present invention, it is possible to easily form the widened portion of the trigger 3 by transfer by providing irregularities on the surface of the mold constituting the side surface of the widened portion 5. 5 can be formed on the side surface.

The trigger according to the present invention is designed to reduce the weight.
It is a hollow body and made of resin. However, since the trigger directly destroys the tubular member, it is preferable to have one or more ribs 8 extending in the axial direction in the hollow as shown in FIG. 2 so as not to deform itself. As a method for manufacturing the trigger, injection molding of a thermoplastic resin is preferable.

The present invention is characterized in that at least one of the surfaces of the trigger and the cylindrical impact energy absorbing member that are in contact with each other is provided with irregularities (roughened). And The surfaces that come into contact with each other are the side surface of the insertion portion and the side surface of the widened portion in the trigger, and the inner wall surface in the cylindrical member. But,
Since it is difficult to provide irregularities on the inner wall surface of the cylindrical member due to the manufacturing method, the irregularities are usually formed on the contact surface of the trigger 3, preferably on the entire side surface of the insertion portion 4 and the widening portion 5, as shown by dots in FIG. Provide.

With the use of the impact energy absorbing device of the present invention, the applied impact energy is consumed by the resistance relating to the "friction" generated when the absorbing member 2 is destroyed, so that the impact energy per unit traveled distance of the trigger 3, that is, the impact energy is absorbed. The amount of impact energy absorbed per breaking distance of the energy absorbing member 2 can be increased. This effect can be confirmed by the fact that the stress value of the stable stress portion of the stress-displacement characteristic curve at the time of fracture increases.

Next, a method of forming the irregularities will be described. When it is desired to form irregularities on the trigger, a trigger with irregularities can be formed by using a mold having irregularities on the inner surface (cavity forming surface). Of course, after molding only the trigger body, the contact surface can be formed with irregularities by sandblasting, wire brushing, sandpaper or the like.

When it is desired to form irregularities on the inner surface of the cylindrical member, the prepreg is wound around a mandrel having irregularities on the outer surface by sandblasting or the like to obtain a cylindrical member having irregularities on the inner surface. Of course, if possible, after manufacturing only the cylindrical member main body, the inner surface thereof can be made uneven by sandblasting or the like.

The blast method is a type of spraying, and is a method in which an abrasive containing particles of an appropriate size is beaten to the surface of a metal or resin to form irregularities on the surface. In the blast method, depending on the type of particles to be sprayed,
There are a sand blast method using sand, a shot blast method using steel grains, a grit blast method using crushed steel granules (grit), and the like. Further, there are a dry type, a warm type, a hydraulic type, and the like, depending on a method of ejecting particles. The spraying method using high-pressure water is also called a liquid honing method.

In addition, non-slip processing can be performed by using an etching method. This is a so-called matte finish or matte finish in which metal is made uneven to prevent slippage.

The degree of unevenness (roughness) may be such that it is usually formed on the surface when metal or plastic is subjected to non-slip processing.

[0028]

Example 1 An impact energy absorbing device of the present invention was manufactured as follows. First, a cylindrical impact energy absorbing member
It was manufactured by a rotary core type injection molding apparatus shown in FIG.
In the figure, 11 is an injection machine, 12 is a sprue of molten polymer, 13 is a runner, 14 is a rotating core, 15 is an outer mold, and 16 is a forming part of a cylindrical body formed by the rotating core 14 and the outer mold 15. (Cavity). 17 is the core 14
, A chain for driving the core 14, a motor 19, and a projecting pin 20.

The molten resin is injected from the injection machine 11 and passes through the sprue 12 and the runner 13 to form the cavity 16.
It is injected into. The rotation speed of the rotating core 14 is 100 to 40
0 rpm, preferably in the range of 200 to 400 rpm. The molten resin injected into the cavity follows the rotating wall surface of the core 14 and is oriented at an angle to the axis of the cylindrical body to be molded. If the bearing 17 is made of an elastic material, there is little risk of seizure during rotation of the core.

The resin used was a thermotropic liquid crystal copolyester resin having a repeating unit derived from phthalic acid / isophthalic acid / 4-hydroxybenzoic acid / 4,4-dihydroxydiphenyl, respectively, in a molar ratio of each. Is 0.75 / 0.25 / 3/1. When this resin was observed for optical anisotropy using a polarizing microscope equipped with a hot stage, it showed optical anisotropy in a molten state at 340 ° C. or higher.

Using a composition containing 30% by weight (based on the whole composition) of glass fiber in this resin, a pipe-shaped cylindrical impact energy absorber having an outer diameter of 32 mm and an inner diameter of 25 mm was obtained by the apparatus shown in FIG. The parts were injection molded. The injection time was about 5 seconds and the cooling time was about 10 seconds, which required a total of about 15 seconds. Observing each of the outer surface and the inner surface of the obtained cylindrical body and confirming the direction of the resin flow from the flow mark, the direction of the resin flow on the outer surface almost coincides with the axial direction of the cylindrical body. The direction of the resin flow on the inner surface was inclined about 33 ° with respect to the axial direction of the cylindrical body.

On the other hand, a resinous trigger was produced by injection-molding the same thermotropic liquid crystal copolyester resin composition used in the molding of the cylindrical body. That is, the molten resin is injected from the sprue 22 of the three-part mold 21 shown in FIG. 4 and filled into the divided cavities 24 and 25 via the sub-sprue 23 to form the divided bodies 26 and 27 constituting a desired trigger. Was molded. Next, after the movable mold 28 is separated from the center slide mold 29 while holding the divided body upper part 26, the slide mold 29 is slid upward together with the divided body lower part 27, and the divided body upper part 26 and the divided body lower part 27 are separated. The two dies 28 and 29 were again assembled so that the dies faced each other (FIG. 5). At this time, the opposing surfaces of the divided bodies were fused together, and the internal rib pieces were firmly joined. This time, the same molten resin is injected from the sprue 22, filled into the joining groove 31 on the outer periphery of the divided body via the sub-sprue 30, and the upper part 26 and the lower part 27 of the divided body are fused and fixed, so that the resin trigger I got

The diameter of the obtained trigger 3 was 24.5 mm at the insertion portion 4, 35 mm at the head 6, and the curvature of the widening portion 5 was R = 7 mm. In addition, since irregularities were formed by sandblasting on the surface of the inner surface of the slide mold 29 facing the surface of the widening portion 5, the irregularities were transferred to the surface of the widening portion 5 of the obtained trigger.

Finally, the resin trigger having the unevenness was inserted into the opening of the cylindrical impact energy absorbing member to complete the impact energy absorbing device of the present invention.

Comparative Example 1 An impact energy absorbing device was manufactured in the same manner as in Example 1 except that the trigger 3 was solid and made of aluminum and no irregularities were formed.

Test Example The impact energy absorbing devices of Example 1 and Comparative Example 1 were subjected to a crush test by lowering a trigger into a cylindrical member at a constant crush speed of 5 mm / min. The load with respect to the displacement was measured, and the result is shown in FIG.

FIG. 6 shows that the impact energy absorbing device of Example 1 has a higher stable fracture stress and is more stable than the device of Comparative Example 1.

[0038]

Since the impact energy absorbing device of the present invention has a hollow trigger and is made of resin, it is suitable for use in a vehicle such as a vehicle requiring light weight. Also,
Since the trigger is made of resin, the degree of freedom of design is large, so that various forms of impact energy absorbing devices can be manufactured using the trigger. In particular, the trigger having the structure as shown in FIG. 2 is excellent in dimensional accuracy and strength because the internal ribs prevent the deformation in the vertical direction and the patch structure prevents the deformation in the horizontal direction.

Further, in the device of the present invention, since one of the surfaces of the trigger and the cylindrical member that are in contact with each other is provided with irregularities, a high frictional resistance is generated between the two members when a load is applied. As a result, the stable fracture stress increases. In addition, since one of the contact surfaces has irregularities, the trigger does not slip and tilt with respect to the cylindrical member when entering the cylindrical member, so that the fracture stress increases and is stabilized.

Particularly, in the case of a cylindrical member having a high inner surface smoothness, for example, a cylindrical impact energy absorbing member manufactured by using a mold having a rotating core, the effect of increasing the frictional stress due to the formation of unevenness is remarkable.

Further, as compared with the R surface of the metal trigger, the R surface of the resin trigger has an advantage that it is easy to provide irregularities and the cost is low. In addition, the ribs are provided inside the aerial trigger and reinforced, so there is little deformation of the trigger.

[Brief description of the drawings]

FIG. 1 is a perspective view of an impact energy absorbing device of the present invention.

FIG. 2 is a partial cross-sectional view of the device.

FIG. 3 is a partial sectional view of a rotary core injection molding apparatus.

FIG. 4 is a sectional view of a molding die for a trigger according to the present invention.

FIG. 5 is a sectional view of a molding die for a trigger according to the present invention.

FIG. 6 is a stress-displacement curve in a test example.

[Explanation of symbols]

1: Impact energy absorbing device, 2: Cylindrical impact energy absorbing member, 3: Trigger, 4: Insertion part, 5: Widening part, 6: Head, 7: Joint, 8: Rib, 11: Injector,
12: sprue, 13: runner, 14: rotating core, 1
5: outer mold, 16: cavity, 17: bearing, 18:
Chain, 19: motor, 20: protruding pin, 21:
Three-part mold, 22: sprue, 23, 30: sub-sprue, 24, 25: split cavity, 26, 27: trigger split body, 28: movable mold, 29: slide mold.

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[Procedure amendment]

[Submission date] July 18, 2000 (2007.1.
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

Change

SUMMARY OF THE INVENTION The object of the present invention is to provide a trigger having a hollow structure made of resin and having no opening, and having one of the surfaces of the trigger and the cylindrical impact energy absorbing member which are in contact with each other. This is achieved by providing irregularities.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

That is, the impact energy absorbing device of the present invention is a shock energy absorbing device having a cylindrical impact energy absorbing member and a trigger, and the trigger is fitted into an opening at one end of the tubular member. An impact energy absorbing device, comprising: an insertion portion that is formed integrally with the insertion portion; and a widened portion that is formed integrally with the insertion portion and has a diameter larger than the insertion portion and having a larger diameter as the distance from the insertion portion increases. The trigger and the cylindrical impact energy absorbing member are provided with irregularities on at least a part of at least one of the surfaces that are in contact with each other. It is characterized by the following.

Claims (2)

[Claims] 1. An impact energy absorbing device comprising a cylindrical impact energy absorbing member and a trigger, wherein the trigger is inserted into an opening at one end of the tubular member and the inserting portion. An impact energy absorbing device having a widened portion integrally formed with the insertion portion and having a diameter larger than a diameter of the insertion portion and having a larger diameter as the distance from the insertion portion increases, wherein the trigger is hollow and made of resin, and An impact energy absorbing device, wherein at least a part of one surface of the cylindrical impact energy absorbing member that is in contact with each other is provided with irregularities. 2. The impact energy absorbing device according to claim 1, wherein the trigger has an axially extending rib in the hollow.