JPH1030669A - Energy absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effect approximate coincidence of an energy curve with an ideal curve, to increase an energy absorption load, and to perform higher energy absorption compared with a conventional type. SOLUTION: An energy absorbing member 1 comprises an approximate cylindrical FRP pipe 10; and a trigger 20 inserted in the FRO pipe 10. The trigger 20 is provided with an insertion part 21 insertable in the opening part on one side of the FRP pipe 10 and an expansion part 22 formed integrally with the insertion part 21 and having a concentrically expanded diameter. The expansion part 22 is provided with first and second inclination parts 23 and 24. Provided an inclination angle between the first inclination part 23 and the central axis O of the FRP pipe 10 is γ1 , and an inclination angle between the second inclination part 24 and the central axis of the FRP pipe 10 is γ2 , an inclination angle is changed in a stepped manner such that a relation of γ1 <γ2 is established.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art For example, in an energy absorbing member used between two members having high rigidity on which an impact load acts,
As one means for absorbing an impact load, see, for example,
Energy absorbing members such as those described in JP-A-13041 and JP-A-4-15332 are known.

As illustrated in FIG. 11, a conventional energy absorbing member 60 has a substantially cylindrical FRP pipe 61 made of glass fiber impregnated and cured with a thermosetting resin.
A slit-shaped notch 64 is provided at a peripheral edge 63 of a tip 62 of the pipe 61, and a first pipe portion 65 that can be inserted inside the peripheral edge 63 as shown in FIG.
The first pipe section 65 is configured by inserting the first pipe section 65 of the inclined tubular pipe 68 as a trigger including the second pipe section 67 having a larger diameter than the first pipe section 65 into the FRP pipe 61.

[0004]

The initial destruction and energy absorption performance of the conventional energy absorbing member 60 depends on the inclination angle θ which is the angle between the central axis of the FRP pipe 61 and one of the inclined portions 66. Will be done. In this case, a slit-shaped notch 64 is provided on the peripheral edge 63 of the tip 62 of the FRP pipe 61 to reduce the initial breaking load. However, if the inclination angle θ is too large, the FRP pipe 61 buckles and breaks when an axial impact load is applied to the inclined tubular pipe 68 as a trigger, so that the inclination angle θ is relatively small. There is a drawback that the energy absorption load must be set low, and the total energy absorption amount as the energy absorption member is low.

Accordingly, an object of the present invention is to provide a large energy absorption amount regardless of the presence or absence of a slit-like notch formed at the peripheral edge of the tip of the FRP pipe, and to make the energy absorption curve closer to an ideal curve; An object of the present invention is to provide an energy absorbing member capable of increasing an energy absorbing load.

[0006]

In order to solve the above problems and achieve the object, an energy absorbing member according to the present invention comprises a pipe made of FRP formed into a substantially cylindrical shape,
The pipe has a substantially cylindrical insertion portion that can be inserted into one end side opening of the pipe, and has a side surface that increases in diameter integrally with the insertion portion and continuously to the insertion portion.
A trigger having a widened portion whose angle with the central axis of the P pipe increases stepwise or continuously as the distance from the insertion portion increases, and the insertion portion of the trigger is inserted into the opening of the FRP pipe. It is constituted by that.

[0007] The energy absorbing member of the present invention sets the inclination angle mainly related to energy absorption separately from the inclination angle mainly related to the initial fracture of the FRP pipe.
Since a desired initial destruction performance can be obtained and a tilt angle related to energy absorption can be increased, it is possible to increase the amount of energy absorption as compared with the related art.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The energy absorbing member 1 shown in FIG. 1 is formed by impregnating and curing a large number of glass fibers or the like with a thermosetting resin and molding the glass fiber into a substantially cylindrical shape.
An FRP pipe 10 made of iber Reinforced Plastics (fiber reinforced plastic) and a trigger 20 inserted into the FRP pipe 10 are provided. The energy absorbing member 1 is provided between a pair of members (members for transmitting a load) not shown.

The FRP pipe 10 is formed by an appropriate manufacturing method such as a well-known filament winding method or a drawing method in accordance with specifications such as required mechanical strength.

The trigger 20 includes a substantially cylindrical insertion portion 21 that can be inserted into an opening on one end side of the FRP pipe 10, and a side surface 22 a that is integral with the insertion portion 21 and has a diameter that expands concentrically with the insertion portion 21. The widened portion 22 is provided.

The widened portion 22 in the illustrated example has a first inclined portion 23 and a second inclined portion 24 formed continuously with the insertion portion 21, and the side surface of the first inclined portion 23 and the FRP The first inclination angle θ1 which is an angle between the central axis O of the pipe 10 and the side surface of the second inclined portion 24 and the FRP pipe 1
A second inclination angle θ2, which is an angle between the center axis O and the center axis O, is θ
The angle is formed stepwise so that the inclination angle gradually increases as the distance from the insertion portion 21 increases so that 1 <θ2. When the first inclined section 23 is press-fitted into the FRP pipe 10, the inclined section 23 having the above-mentioned inclination angle θ1 causes an initial breakage at the opening end of the FRP pipe 10 as if it were a “wedge”. Therefore, in order to minimize the difference with the energy absorption load described later, it is desirable that θ1 is a relatively small angle of 90 degrees or less. For example, the inclination angle θ
If 1 exceeds 90 degrees, FRP will occur at the stage of initial destruction.
The pipe 10 is broken due to buckling or the like, and the difference from the subsequent energy absorbing load becomes large, so that the shock absorbing effect is greatly reduced. Therefore, θ1 is set to an angle smaller than 90 degrees. On the other hand, the inclination angle θ2 is desirably a relatively large angle (for example, about 90 degrees) in order to maximize the energy absorption load.

The FRP pipe 10 is formed in a straight tubular shape so that the inner diameter and the outer diameter are substantially constant in the axial direction of the pipe 10, respectively. However, when the strength of the FRP pipe 10 itself and the combination of the inclination angle θ1 and the inclination angle θ2 are also taken into consideration, the graph of the energy absorption curve 30 shown in FIG. Become. Here, FIG. 6 schematically shows an energy absorption curve of the energy absorbing material of the present embodiment.

Further, the peak of the initial breaking load 31 is further reduced. In other words, in order to make the initial breaking load 31 and the energy absorbing load 32 equal, FIG.
The shape of the open end of the FRP pipe 10, that is, the shape of the peripheral portion 12 of the tip 11 on the side where the trigger 20 is inserted may be changed as shown in FIG.

FIG. 2 shows an example in which a slit-shaped notch 13 is provided in a peripheral portion 12 of the tip 11 of the FRP pipe 10 on the trigger insertion side in the axial direction of the pipe (Claim 2). An example in which a tapered portion 14 whose thickness changes so that the inner diameter is constant and the outer diameter gradually decreases as the tip 11 is moved, is provided on the peripheral edge portion 12 of the tip 11 on the trigger insertion side. ).

The trigger 20 is desirably a solid metal material. However, the trigger 20 can maintain sufficient rigidity against the initial breaking load 31 and the energy absorbing load 32 of the FRP pipe 10 shown in FIG. If there is, a hollow insertion portion 21 and inclined portions 23 and 2 as in a trigger 20 shown in FIG.
4 may be used.

The operation of the energy absorbing member 1 shown in FIG. 1 when absorbing an impact will be described below. As shown in FIG. 5A, when an impact load 40 is applied from at least one of the trigger 20 side and the FRP pipe 10 side, the trigger load 20 is further applied to the FRP pipe 10
Acts in the direction of entering. 26 is a trigger 20
Shows the center of gravity. The trigger 20 is provided with the impact load 40
The first inclined portion 23
Causes a widening force 41 to expand the tip 11 of the FRP pipe 10 in the circumferential direction of the FRP pipe 10.

The widening force 41 is applied to the FRP pipe 1
When the strength in the circumferential direction exceeds 0, the tip 11
Cracks occur in the periphery. In this specification, the load acting on the center of gravity 26 of the trigger 20 when the crack occurs is referred to as an initial breaking load 31 shown in FIG. When the trigger 20 is further pushed in the direction of the pipe 10 and the second inclined portion 24 comes into contact with the tip 11 of the pipe 10, FIG.
As shown in (B), the second inclined portion 24 acts in a direction to further expand the peripheral portion 12 of the tip 11, and the FRP pipe 10 is radially divided from the tip 11. The load acting on the center of gravity 26 of the trigger 20 at the time of the division is referred to as an energy absorbing load 32 shown in FIG.

According to the energy absorbing member 1 of the above embodiment, the inclination angle θ1 is set to a relatively small angle, and the slit-shaped notch 13 is provided if necessary.
6 can be made relatively low, and the energy absorption load 32 shown in FIG. 6 can be made relatively large by setting the inclination angle .theta.2 to a relatively large angle.

The results of an impact load test conducted to confirm the operation of the energy absorbing member 1 of the above embodiment will be described below with reference to FIGS. FIG. 7 is a diagram showing the form of the trigger used in this experiment.
7A shows a conventional trigger, and FIG. 7B shows a trigger according to the present invention. 7 (A) shows a conventional product having an inclination angle θ of about 45 degrees, and FIG. 7 (B) shows an inclination angle θ1 of the first inclination section 23 of about 45 degrees and an inclination angle of the second inclination section 24. θ2 is approximately 90 degrees. Each of the FRP pipes used had a glass content of 67% by weight.

FIG. 8 is a view showing an energy absorbing member used in this experiment. FIG. 8A shows a comparative example 1 in which a conventional trigger is set to an FRP pipe without a notch,
FIG. 8B shows a comparative example 2 in which a conventional trigger is set in a notched FRP pipe, and FIG. 8C shows a trigger according to the present invention set in a notched FRP pipe. FIG. 9 is a diagram showing the results of this experiment.

As shown in FIG. 9, as a result of this experiment, the effect of the trigger shape on the energy absorption load is first determined. In the present invention, the inclination angle θ2 mainly relating to energy absorption is reduced by about the inclination angle θ of Comparative Example 2. By making it twice, the energy absorption load becomes about 1.5 times. Also, as shown in Comparative Example 1, unless a slit-shaped notch is provided at the periphery of the tip of the FRP pipe, the initial breaking load is very large, and an ideal energy absorption curve cannot be obtained. Approximately 4
This is because the angle is set to a relatively large angle of 5 degrees. In this case, a notch is required in the FRP pipe. On the other hand, in the product of the present invention, even if the first inclination angle θ1 involved in the initial fracture is reduced to 45 degrees or less, the total energy absorption can be increased by the presence of the second inclination angle θ2. Since it is possible, an ideal energy absorption curve can be obtained regardless of the presence or absence of the slit notch.

The energy absorbing member shown in the embodiment including the above-mentioned experimental example includes the following modified examples of the trigger. The trigger 50 shown in FIG. 10 has a substantially columnar insertion portion 51 that can be inserted into the one end side opening of the FRP pipe 10 similarly to the first embodiment, and is integrated with the insertion portion 51 and provided in the insertion portion 51. Widening portion 5 whose diameter is continuously increased concentrically
Three. However, the widened portion 53 is a curved inclined portion 52. The inclined portion 52 is a rotating body having an arc of about a quarter of a circle. The inclined angle θ3, which is the angle between the tangent of the inclined portion 52 and the central axis O of the FRP pipe, gradually increases as the distance from the insertion portion 51 increases. To change continuously. In the modified example of the trigger 50 having such a widened portion 53, the FRP pipe 10
Because the inclination angle mainly involved in the initial fracture can be made relatively small and the inclination angle mainly involved in the energy absorption can be made relatively large, the rise of the initial fracture load becomes gentle and the total Energy can be increased.

As described above, with respect to the initial load of the energy absorbing member and the inclination angle of the trigger which controls the energy absorbing load, the inclination angle mainly relating to the initial fracture and the inclination angle mainly relating to the energy absorption are separately set. Because you can
The first inclination angle mainly involved in the initial fracture is set to a relatively small angle, and the initial fracture load can be kept relatively low.The second inclination angle mainly involved in the energy absorption is set to a relatively large angle. It is possible to increase the energy absorption load.

[0024]

The energy absorbing member of the present invention is mainly composed of F
The inclination angle that affects the initial fracture of the RP pipe and the inclination angle that mainly affects the energy absorption can be set separately. Regardless of whether or not a slit-shaped notch is formed at the tip periphery, the initial fracture load can be suppressed, buckling of the FRP pipe can be prevented, and the inclination angle mainly involved in energy absorption is relatively large. Therefore, it is possible to realize a higher energy absorption load than before. Therefore, the energy absorption curve can be made closer to the ideal curve.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along an axial direction of an energy absorbing member according to an embodiment of the present invention.

FIG. 2 is a side view showing the vicinity of an end of the FRP pipe.

FIG. 3 is a side view showing a modification of the end of the FRP pipe.

FIG. 4 is a sectional view showing a modified example of the trigger according to the embodiment of the present invention.

FIG. 5 is a sectional view showing a direction of a load applied to the trigger of the embodiment shown in FIG. 1 and the like;

FIG. 6 is a diagram schematically showing an energy absorption curve of an energy absorbing member.

FIG. 7 is a side view of a trigger used in an impact load test.

FIG. 8 is a side view of a part of the energy absorbing member used in the impact load test.

FIG. 9 is a diagram showing an energy absorption curve obtained by an impact load test on the product of the present invention and a comparative example.

FIG. 10 is a side view showing a modification of the trigger.

FIG. 11 is a side view showing a conventional energy absorbing member.

FIG. 12 is a sectional view taken along the line XII-XII in FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Energy absorption member 10 ... FRP pipe 20 ... Trigger 21 ... Insertion part 22 ... Widening part 23 ... First inclination part 24 ... Second inclination part θ1 ... First inclination angle θ2 ... Second inclination angle

Claims (3)

[Claims] 1. An energy absorbing member provided between a pair of members for reducing an impact load transmitted to a member on the other side when an impact load is applied from one side, comprising: an FRP formed in a substantially cylindrical shape; A pipe having a substantially columnar insertion portion that can be inserted into one end side opening of the FRP pipe, and a side surface having a diameter that is integral with the insertion portion and that continuously increases in diameter to the insertion portion. And a trigger having a widened portion in which the angle between the central axis of the FRP pipe and the insertion portion increases stepwise or continuously as the distance from the insertion portion increases, and the insertion portion of the trigger is inserted into the opening of the FRP pipe. An energy absorbing member having been inserted. 2. The energy absorbing member according to claim 1, wherein a slit-shaped notch is provided along a periphery of the opening of the FRP pipe on the trigger insertion side along the axial direction of the FRP pipe. 3. The FRP pipe according to claim 1, wherein a tapered portion whose inner diameter is substantially constant and whose outer diameter gradually decreases toward the tip of the pipe is provided at a peripheral edge of the opening on the trigger insertion side of the FRP pipe. The energy absorbing member as described in the above.