JP5130492B2 - Underrun protector for vehicles with excellent buckling resistance - Google Patents

Description

  The present invention relates to an underrun protector provided at the front lower part or rear rear part of a vehicle for preventing one vehicle from entering under the other vehicle at the time of collision between the vehicle and the vehicle.

  In a rear-end collision between a truck and a passenger car or a frontal collision accident, the passenger car may sink into the front or rear lower part of the truck, causing serious damage to passengers on the passenger car side. Against this background, in Europe, the development of an underrun protector to be installed on the truck side was started to reduce the damage to passengers due to collisions. After that, a full-scale study was promoted toward legalization, and from 2003, large and medium trucks were required to be equipped with underrun protectors. On the other hand, underrun protectors are also being studied in Japan, and in the fall of 2011, front underrun protector (FUP) equipment that prevents passenger cars from entering the bottom of a truck during a frontal collision was legalized. The equipment of the rear underrun protector (RUP) that prevents passenger cars from entering the rear of the truck during rear-end collisions is regulated by law.

  The underrun protector is located at the lower part of the front or rear of the truck at a height that wraps with the side member or frame of the passenger car. This is a device that prevents this. Therefore, underrun protectors are effective in reducing damage to passenger cars and improving loading efficiency. In particular, the development of underrun protectors that satisfy both impact strength and weight reduction is essential. .

As shown in FIG. 6, the conventional underrun protector includes an underrun protector main body 11 that is arranged extending in the vehicle width direction at the front lower part or rear lower part of the vehicle, the underrun protector main body 11 and the vehicle body. It is comprised with the bracket 13 which connects the flame | frame 12. As shown in FIG. The bracket 13 is fastened to the non-load side surface of the underrun protector body 11. A conventional underrun protector is required to have a high buckling strength because it bears a collision load. For this performance requirement, in Europe, as shown in FIG. 7, a load mode at the time of a vehicle collision is simulated, and a predetermined distance (for example, 200 mm from the side surface of the tire 21) is set at a predetermined position inside the vehicle. A test is performed to load a load P ₁ (for example, 25% of the vehicle weight). When such a load is applied to the underrun protector main body 11, a moment is generated around the fastening portion S between the underrun protector main body 11 and the bracket 13 (arrow M in FIG. 7). There is a problem that stress concentrates on the fastening portion S on the non-load side of the main body 11, the underrun protector main body 11 easily buckles, and the specified collision strength cannot be obtained.

  As a method for increasing the buckling resistance of conventional underrun protectors, addition of reinforcing parts such as reinforcement and gusset has been proposed (for example, Patent Documents 1 to 4). Since the weight of the protector increases, it is not easy to achieve both improvement in buckling strength and weight reduction.

On the other hand, high-strength steel sheets are being applied to vehicle body frame parts as a solution in order to satisfy vehicle weight reduction and collision safety at the same time in passenger cars. However, in underrun protectors, it is necessary to optimize the entire design through parts design, materials, and processing methods in order to select the optimal material and thickness from various strength classes and reduce the weight without impairing the impact performance. Yes, it is not easy to optimize compared to the case of using a lot of conventional mild steel sheets, and there has been no example of applying high-strength steel sheets to underrun protectors.
JP 2004-243984 A JP 2005-225326 A JP 2006-36071 A JP 2008-62838 A

  In view of the above, the present invention has an object to provide an underrun protector that is lightweight and has excellent buckling resistance.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that an underrun protector body that is disposed at the front or rear part of the vehicle and extends in the vehicle width direction, and a reinforcement that is a reinforcement part of the underrun protector body. And a bracket for fixing the underrun protector body to the body frame and a gusset that is a reinforcing part of the bracket. By optimizing these structures, the underrun is lightweight and has excellent buckling resistance. -The present invention was completed by finding that a protector was obtained. Further, the present inventors further use a high-strength steel plate having a tensile strength of at least one member among the constituent members of the underrun protector in the range of 590 to 1450 MPa. It has been found that the weight can be reduced and the buckling resistance can be improved.

The gist of the present invention is as follows.
(1) An underrun protector body that is disposed at the front or rear of the vehicle and extends in the vehicle width direction, and the underrun protector body is fixed to a vehicle body frame of the vehicle, and the underrun protector body A pair of brackets spaced apart along the vehicle width direction and a reinforcing part of the underrun protector main body, the non-load of the underrun protector main body along the longitudinal direction of the underrun protector main body And the bracket, wherein the longitudinal dimension is set to be longer than the length between the pair of brackets , and the positions of the ends at both ends in the longitudinal direction are located outside the pair of brackets , Ri Na comprises a, and gussets to reinforce the connection portion of the underrun protector body, wherein When the length between the pair of brackets is L _B [mm], the longitudinal dimension of the reinforcement is in the range of 1.4 L _{B to} 1.8 L _B [mm]. Vehicle underrun protector .
( 2 ) At least one member of the underrun protector body, the reinforcement, the bracket, and the gusset has a high tensile strength of a material in a range of 590 MPa class or more and 1450 MPa class or less. The underrun protector having excellent buckling resistance according to (1) , which is made of a high strength steel plate.
( 3 ) The underrun protector body includes a load portion that receives a load, a non-load portion that is disposed on the opposite side of the load portion, and a pair of connection portions that connect the load portion and the non-load portion. It is composed of a sectioned hollow cylindrical member, and the reinforcement is folded at both ends of the reinforcement main body and the reinforcement main body to be joined to the non-loading portion of the underrun protector main body. A pair of reinforcements that are bent and joined to the connecting portion of the underrun protector body, and the reinforcement body portion is connected to the underrun protector body and the bracket at the connection portion between the underrun protector body and the bracket. characterized in that it is disposed between the run-protector body and said bracket (1) to to any one of (2) Underrun protector with excellent buckling resistance of the mounting.
( 4 ) The bracket includes a bracket body that connects the body frame and the underrun protector body, and a bracket reinforcement body that reinforces the bracket body, and is bent at both lateral ends of the bracket body. (1) to ( 3 ) characterized in that a concave portion is formed in the bracket body by providing a portion, and the bracket reinforcing body is fitted into the concave portion to form a closed cross-sectional shape. The underrun protector excellent in buckling resistance according to any one of the above.
( 5 ) Any one of (1) to ( 4 ), wherein the gusset is a substantially triangular plate member and is provided between the underrun protector body and the bracket. The underrun protector with excellent buckling resistance as described in the item.

  ADVANTAGE OF THE INVENTION According to this invention, the underrun protector which was lightweight and excellent in buckling resistance can be provided.

Hereinafter, the present invention will be described in detail.
The underrun protector is located at the lower part of the front or rear of the truck, at a height that wraps with the side member or frame of the passenger car. It is a device that prevents the dive.
Therefore, underrun protectors are effective in reducing damage to passenger cars and improving loading efficiency. In particular, development of underrun protectors that satisfy both impact strength and weight reduction is indispensable. Here, the underrun protector according to the present invention, which is lightweight and has excellent buckling resistance, is studied in detail with respect to the conventional shape of FIG. 6 as an underrun protector, and the result is reflected in the improvement of the underrun protector. The process of completing is described in detail.

  First, in order to fix the underrun protector main body 11 to the vehicle frame 12 and the underrun protector main body 11 composed of a square pipe made of a 400 MPa class high strength steel plate having a thickness of 4.5 mm as a conventional underrun protector. Deformation modes and reaction force characteristics of the underrun protector composed of the bracket 13 made of a 440 MPa class high-strength steel plate will be described with reference to FIGS. 6 shows the structure of a conventional underrun protector, FIG. 7 is a diagram showing the input position of a collision load and the moment generated thereby, and FIG. 1 shows the deformation mode and strain state of the underrun protector with respect to the input load. FIG. 1A is a schematic diagram illustrating a state before deformation, and FIG. 1A is a schematic diagram illustrating a state after deformation.

As the strength requirement for the underrun protector, there is a strength requirement for replacing a collision with a static load and defining a displacement amount with respect to the load. For example, in Europe, as shown in FIG. 7, the displacement / rotation of the vehicle frame 12 is constrained, and as shown in FIG. 1A, the load element (P ₁ ) At a constant speed. Again, following the European evaluation test, the relationship between reaction force acting on the loader and displacement was examined.

  The reaction force of the loader increases monotonously with the penetration of the loader, but when the load exceeds the buckling strength of the underrun protector main body 11, the maximum value is observed, and then starts to decrease. This is because the moment M centered on the fastening portion S between the underrun protector body 11 and the bracket 13 is generated, and stress concentrates on the fastening portion S on the non-load side of the underrun protector body 11 as shown in FIG. This is because buckling occurs as shown in b). In addition, the residual distortion of about 0.02 exists in the deformation | transformation part after buckling. From such a point of view, the inventors have considered the deformation mechanism of the underrun protector and conceived that reinforcement of the fastening portion S between the underrun protector body 11 and the bracket 13 is effective for improving the buckling resistance. did.

  In order to reinforce the fastening portion S, it is effective to arrange a reinforcement along the longitudinal direction of the underrun protector main body 11. However, the reinforcement of the underrun protector can increase the weight of the underrun protector as a whole. Therefore, here, the shape of the reinforcement that effectively improves the buckling resistance performance while suppressing the increase in weight as much as possible was examined.

The optimization of the reinforcement part by reinforcement is demonstrated using FIG. 2 and FIG.
Here, the underrun protector body 1 made of a square pipe made of a 1.4 mm thick 980 MPa class high strength steel plate is provided with a reinforcement 4 made of a 1.4 mm thick 980 MPa class high strength steel plate and having a different overall length. The reaction force characteristics and deformation modes with respect to mounting and loader input were analyzed. FIG. 3 shows the relationship between the weight of the underrun protector body 1 plus the reinforcement 4 and the bracket 3 and the member deformation reaction force.

The symbol h in FIGS. 2 and 3 is an example without reinforcement in which the reinforcement 4 is not attached to the underrun protector body 1.
The symbol a is an example in which the reinforcement 4 surrounding both the load side and the non-load side of the underrun protector body 1 is attached to the fastening portion between the underrun protector body 1 and the bracket. This is an example in which a reinforcement 4 having a length twice that of the case a is attached to the fastening portion between the run protector body 1 and the bracket 3, and the reference c is an underrun protector body 1 and the bracket 3. This is an example in which a reinforcement 4 having a length three times that in the case of the symbol a is attached to the fastening portion.
Further, symbol d is an example in which a reinforcement 4 having the same length as that of symbol a is attached to the non-load side of the fastening portion between the underrun protector main body 1 and the bracket. This is an example in which the reinforcement 4 having the same length as that of the symbol a is attached to the load side of the fastening portion of the bracket.
Further, the symbol f is an example in which the reinforcement 4 is attached to the non-load side of the underrun protector main body 1, and the symbol g is a rain force 4 longer than the symbol f on the non-load side of the underrun protector main body 1. It is the example which attached. In addition, the total length of the reinforcement 4 with the symbol f is 1.2 times the distance between the brackets, and the overall length of the reinforcement 4 with the symbol g is 1.6 times the distance between the brackets.

As shown by reference signs a to f in FIG. 3, when the reinforcement region by the reinforcement 4 is expanded, the reaction force characteristics are improved, but the buckling point Z transitions outside the reinforcement as shown in FIG. 2. On the other hand, if it reinforce | strengthens like the code | symbol g, it will buckle within the reinforcement by the reinforcement 4, and the reaction force characteristic will improve significantly compared with the code | symbol f.
Further, it has been clarified that the reaction force characteristic is improved by reinforcing only the non-load side as indicated by symbol e rather than reinforcing only the load side as indicated by symbol d.
As mentioned above, by optimizing the reinforcing parts, buckling performance can be improved while minimizing weight increase. Between the underrun protector body on the non-load side and the bracket, the length between the left and right brackets is 1. It has been found that it is optimal to reinforce within the range of 4 to 1.8 times.

Next, the underrun protector that is lightweight and excellent in buckling according to the present invention will be specifically described with reference to FIGS. 4 and 5. FIG.
As shown in FIGS. 4 and 5, the underrun protector of the present embodiment includes an underrun protector main body 1, a pair of brackets 3 that fix the underrun protector main body 1 to a vehicle body frame 2, and an underrun protector. The reinforcement 4 includes a reinforcement 4 that is a reinforcing part of the run protector main body 1, and a gusset 5 that reinforces a connection portion of the bracket 3 and the underrun protector main body 1.

  The underrun protector main body 1 is disposed at the front or rear portion of the vehicle and extends in the vehicle width direction. The underrun protector body 1 is made of a high strength steel plate having a tensile strength of 980 MPa, for example, having a thickness of 1.4 mm. The underrun protector main body 1 is formed by forming this high-strength steel plate into a square pipe shape. The underrun protector main body 1 is a load portion 1a that receives a load, a non-load portion 1b that is disposed on the opposite side of the load portion 1a, and a load portion. A partition is formed by a pair of connecting parts 1c that connect 1a and the non-loading part 1b.

The pair of brackets 3 are for fixing the underrun protector main body 1 to the vehicle body frame 2 of the vehicle, and are spaced apart from each other along the vehicle width direction of the underrun protector main body 1.
The bracket 3 includes a bracket body 3a that connects the vehicle body frame 2 and the underrun protector body 1, and a bracket reinforcing body 3b that reinforces the bracket body 3a. Bending portions 3c are provided at both ends of the bracket main body 3a in the short direction, thereby forming recesses 3d in the bracket main body 3a. The bracket reinforcing body 3b is provided with bent portions 3e at both ends in the longitudinal direction. And the closed cross-sectional shape enclosed by the bending part 3c of the bracket main body 3a and the bending part 3e of the bracket reinforcement body 3b is formed by fitting the bracket reinforcement body 3b in the recessed part 3d.
Moreover, the bracket main body 3a and the bracket reinforcement body 3b are made of a high-strength steel plate having a tensile strength of 780 MPa, for example, having a thickness of 3.5 mm.

Next, the reinforcement 4 is a reinforcing component of the underrun protector main body 1 and is attached to the non-load side of the underrun protector main body 1 along the longitudinal direction of the underrun protector main body 1. Reinforce 4 is made of, for example, a high-strength steel plate having a tensile strength of 980 MPa having a thickness of 1.4 mm.
The reinforcement 4 includes a reinforcement body 4a that is joined to the non-load portion 1b of the underrun protector body 1 and a connecting portion of the underrun protector body 1 that is bent at both ends in the short direction of the reinforcement body 4a. It is comprised from a pair of reinforcement part 4b joined to 1c, and this reinforcement 4 is engage | inserted by the non-load side of the underrun protector main body 11. FIG. In addition, a reinforcement main body portion 4 a is disposed between the underrun protector main body 1 and the bracket 3 at a connection portion between the underrun protector main body 1 and the bracket 3.

Further, the longitudinal dimension of the reinforcement 4 is preferably set longer than the length L _B between the pair of brackets 3, the total length of the reinforcement 4, the length L _B between the pair of brackets 3 1.4 It is more preferable to set it in the range of double to 1.8 times. The total length of the reinforcement 4 With 1,4 times the length L _B between the bracket 3, can be buckled in the reinforcement, it increased the strength of the underrun protector body 1. Further, by making the total length of the reinforcement 4 and less 1,8 times the length L _B between the bracket 3, it can be suppressed weight increase due to reinforcement 4.

  Further, the gusset 5 reinforces the connection portion between the bracket 3 and the underrun protector body 1, and the gusset 5 is formed as a substantially triangular plate, and is hung between the underrun protector body 1 and the bracket 3. Provided. The gusset 5 is made of, for example, a 3.5 mm thick 780 MPa class high strength steel plate. By providing the gusset 5, the underrun protector body 1 can be further reinforced.

  Further, at least one member of the underrun protector main body 1, the reinforcement 4, the bracket 3, and the gusset 5 has a high strength in the range of 590 MPa or higher and 1450 MPa or lower in terms of the tensile strength of the material. It is preferable to be comprised with the steel plate. Moreover, since the underrun protector main body 1 and the reinforcement 4 are relatively large members, the plate thickness is preferably in the range of 1.2 to 3.2 mm. On the other hand, since the bracket 3 and the gusset 5 are smaller members than the underrun protector body 1 and the reinforcement 4, there is no possibility of preventing weight reduction even if the plate thickness is increased. It is preferable to be in the range of .5 mm. Thereby, the improvement of buckling resistance and weight reduction of an underrun protector can be achieved simultaneously.

FIG. 5 shows the relationship between the weight of the underrun protector and the member reaction force. The dotted line in FIG. 5 shows the target performance of the reaction force.
In FIG. 5, the symbol n is an example of the conventional underrun protector shown in FIG. 6 in which all of the constituent members are made of 400 MPa class steel plates having a thickness of 4.5 mm, and the reaction force is 25 kN. The weight is as large as 22.5kg.
Next, the symbol i in FIG. 5 is an example having the same configuration as the underrun protector shown in FIG. 6 and all the constituent members are made of 980 MPa class steel plates having a thickness of 1.4 mm. In this example, although the weight is 10 kg or less, the reaction force is greatly reduced.
Next, the symbol j in FIG. 5 is obtained by replacing only the bracket of the underrun protector shown in FIG. 6 with the bracket shown in FIG. 4, and the bracket is a 3.5 mm thick 780 MPa class high strength steel plate. This is an example in which all other constituent members are made of a 980 MPa class steel plate having a thickness of 1.4 mm. In this example, the reaction force is improved as compared with the symbol i by the bracket having the closed cross-sectional structure, but it is not sufficient yet.

Next, reference numeral k in FIG. 5, of the underrun protector shown in FIG. 6, replacing the bracket showing the bracket in FIG. 4, further attaching a reinforcement of 1.4 times the total length of the bracket distance L _B, The bracket is composed of a 3.5 mm thick 780 MPa class high strength steel plate, the reinforcement is composed of a 1.4 mm thick 980 MPa class high strength steel plate, and all other components are composed of a 1.4 mm thick 980 MPa class steel plate. This is a configured example. In this example, the reaction force is further improved by the bracket having a closed cross-sectional structure and the reinforcement as compared with the symbol i, but it is not sufficient.

  Next, reference numeral 1 in FIG. 5 is an example in which all the constituent members are made of a 980 MPa class steel plate having a thickness of 2.3 mm, which has the same configuration as the underrun protector shown in FIG. In this example, the reaction force almost reaches the target value (25 kN), but the weight is about 13 kg, and the weight reduction is not sufficient.

Next, the symbol m in FIG. 5 replaces the bracket of the underrun protector shown in FIG. 6 with the bracket shown in FIG. 4, and further attaches a reinforcement having a total length of 1.4 times the distance L _B between the brackets. In addition, a gusset as shown in FIG. 4 is attached, the bracket and the gusset are composed of a 780 MPa class high strength steel plate having a thickness of 3.5 mm, and all other constituent members are composed of a 980 MPa class steel plate having a thickness of 1.4 mm. Yes, this corresponds to the underrun protector of the present embodiment shown in FIG. In this example, the reaction force is improved to 28 kN, the weight is also 12.2 kg, and it can be seen that weight reduction has been achieved.

  As described above, according to the present invention, a high-strength steel plate having an optimum tensile strength is selected, and the reinforcement and underrun protector provided along the longitudinal direction of the underrun protector body are fixed to the body frame. By optimizing the bracket material and structure, it is possible to obtain an underrun protector that is lightweight and has excellent buckling resistance.

  In addition to the optimal placement of high-strength steel plates on the underrun protector body 1 and the bracket 3, the bracket 3 is closed, the underrun protector body 1 is reinforced on the non-load side, and the bracket 3 is provided with a gusset 5. An underrun protector with excellent weight reduction and buckling resistance can be obtained by adding a buckling strength.

FIG. 1 is a schematic diagram showing a deformation mode and strain distribution with respect to an input load of an underrun protector. FIG. 2 is a schematic diagram showing the reinforcement arrangement and the deformation mode of the underrun protector. FIG. 3 is a graph showing the weight and buckling strength of the underrun protectors of FIGS. 4A and 4B are diagrams showing an underrun protector according to an embodiment of the present invention, where FIG. 4A is a perspective view and FIG. 4B is a plan view. FIG. 5 is a graph showing the relationship between the weight of the underrun protector and the buckling strength. FIG. 6 is a partially enlarged view showing an appearance of a conventional underrun protector. FIG. 7 is a schematic diagram showing the input position of the collision load of the underrun protector and the moment generated thereby.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Underrun protector main body, 1a ... Load part, 1b ... Non-load part, 1c ... Connection part, 2 ... Body frame, 3 ... Bracket, 3a ... Bracket main body, 3b ... Bracket reinforcement body, 3c ... Bending part, 3d ... recess, 4 ... reinforce, 4a ... reinforce body part, 4b ... reinforce bent part, 5 ... gusset.

Claims (5)

An underrun protector body disposed in the front or rear of the vehicle and extending in the vehicle width direction;
A pair of brackets for fixing the underrun protector main body to a vehicle body frame of the vehicle and spaced apart along the vehicle width direction of the underrun protector main body,
The underrun protector main body is a reinforcing part and is attached to the non-load side of the underrun protector main body along the longitudinal direction of the underrun protector main body, and its longitudinal dimension is longer than the length between the pair of brackets. Is also set long, the position of the ends of both ends in the longitudinal direction is located outside the pair of brackets ,
Ri Na comprises a, and gussets to reinforce the connection portion of the bracket and the underrun protector body,
When the length between the pair of brackets is L _B [mm], the longitudinal dimension of the reinforcement is in the range of 1.4 L _{B to} 1.8 L _B [mm]. Excellent underrun protector for vehicles. At least one member of the underrun protector body, the reinforcement, the bracket, and the gusset is a high-strength steel plate having a tensile strength of a material in a range of 590 MPa to 1450 MPa. The underrun protector excellent in buckling resistance according to claim 1 , wherein the underrun protector is configured. The underrun protector body is defined by a load portion that receives a load, a non-load portion that is disposed on the opposite side of the load portion, and a pair of connection portions that connect the load portion and the non-load portion. A hollow cylindrical member,
The reinforce is joined to the unloaded portion of the underrun protector main body, and the connecting portion of the underrun protector main body is bent at both ends in the short direction of the reinforce main body. The reinforcement main body portion is disposed between the underrun protector main body and the bracket at the connecting portion between the underrun protector main body and the bracket. underrun protector having excellent buckling resistance according to any one of claims 1 to 2, characterized in that it is. The bracket is composed of a bracket body that connects the body frame and the underrun protector body, and a bracket reinforcing body that reinforces the bracket body, and bent portions are provided at both ends in the short direction of the bracket body. recess is formed in the bracket body by being any of claims 1 to 3 that is characterized in that characterized in that said bracket reinforcing member is fitted into in the recess closed section is formed The underrun protector with excellent buckling resistance according to claim 1. The said gusset is made into the substantially triangular-shaped board | plate material, and is provided across the said underrun protector main body and the said bracket, It is any one of Claim 1 thru | or 4 characterized by the above-mentioned. Underrun protector with excellent buckling resistance.

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