Under protector

Abstract

We offer a lightweight under protector that provides high load-bearing capacity. [Solution] An underprotector 1 made of an aluminum alloy extruded material comprising a rear flange 31, a collision surface flange 32, an upper web 41, a lower web 42, and an intermediate web 43, wherein at least one web is configured as a thickness-variable web with three regions having different thicknesses: a rear side region 51, a collision surface side region 52, and an intermediate region 53 between them, the rear side region 51 having the thickest thickness and the intermediate region 53 having the thinnest thickness.

Description

Technical Field

[0001] The present invention relates to an under protector mounted on a vehicle.

Background Art

[0002] An under protector (intrusion prevention device) is mounted on a large vehicle such as a truck to prevent a collided passenger car or the like from getting under the large vehicle.

[0003] The under protector is required to have a load-bearing performance for preventing intrusion during a collision, and is also required to be lightweight for increasing the loading capacity and improving the fuel efficiency.

[0004] Patent Document 1 proposes an under protector that can achieve a predetermined impact load while reducing the weight by making the thickness of the uppermost web thicker than the thickness of the web below it and suppressing the deformation of the uppermost web.

[0005] Patent Document 2 proposes an under protector that can efficiently improve the rigidity while suppressing an increase in weight by increasing the plate thickness on the vehicle body frame side of the web.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, while the under protector shapes proposed in references 1 and 2 achieve weight reduction while maintaining the required strength compared to those with a cross-sectional shape of uniform thickness throughout, further weight reduction is required to increase load capacity and improve fuel efficiency.

[0008] The objective of this invention is to provide an under protector that is lightweight while possessing high load-bearing capacity. [Means for solving the problem]

[0009] To solve the above problems, the present invention comprises the following means.

[0010] [1] An under protector made of an aluminum alloy extruded material, The device comprises a rear flange erected on the vehicle side, a collision surface flange erected at a distance from the rear flange, an upper web connecting the upper part of the rear flange and the collision surface flange, a lower web connecting the lower part of the rear flange and the collision surface flange, and an intermediate web connecting the rear flange and the collision surface flange at a height between the upper web and the lower web. At least one of the upper web, the intermediate web, and the lower web comprises three regions: a rear-side region located on the rear flange side, an impact-side region located on the impact-side flange side, and an intermediate region located between these, and is configured as a thickness-variable web with different thicknesses in each of these three regions. An underprotector characterized in that, in the aforementioned thickness-variable web, the thickness of the back side region is the thickest, and the thickness of the intermediate region is the thinnest.

[0011] [2] The under protector according to item 1 above, wherein the thickness of the intermediate region is 2 mm or more and the length is 5 mm or more.

[0012] [3] The underprotector according to paragraph 1 or 2, wherein the length of the back side region is 35% to 45% of the total length of the thickness-changing web.

[0013] [4] The underprotector according to any one of paragraphs 1 to 3 above, wherein the length of the intermediate region is 25% to 35% of the total length of the thickness-changing web.

[0014] [5] The under protector according to any one of paragraphs 1 to 4 above, wherein the rear side region, the collision surface side region, and the intermediate region are each composed of a constant thickness. [Effects of the Invention]

[0015] According to the under protector described in the previous section [1], by dividing at least one web into three regions with different thicknesses as a thickness-variable web and setting the thickness according to its influence on the strength (maximum load) in each region, it is possible to reduce weight while obtaining high load-bearing performance. Specifically, the thickness of the rear region, which is adjacent to the rear flange fixed by the bracket and therefore experiences the greatest deformation and the highest stress load, is made the thickest, thus preventing buckling in the rear region and obtaining high load-bearing performance. Furthermore, the thickness of the intermediate region, which experiences almost no deformation and has a low stress load under the P2 load directly above the bracket fixing part, is made the thinnest, thus reducing weight without lowering the P2 load. In addition, by providing the thinnest portion in the intermediate region, a small deformation is induced in that portion, suppressing excessive deformation in the rear region and reducing the load on the rear region, thereby improving load-bearing performance from this point as well.

[0016] According to the under protector described in the previous section [2], even in the thinnest intermediate region, it has a wall thickness of 2 mm or more and a length of 5 mm or more, thus enabling stable extrusion molding.

[0017] According to the underprotector described in the previous section [3], the thickness of the back side region is increased in the area of ​​the web from the back flange to a length of 35% to 45% of the total length of the web, which is prone to buckling, thus providing high load-bearing capacity.

[0018] According to the under protector of the preceding item [4], since the length of the intermediate region with the thinnest wall thickness is suppressed to 25% - 35% of the total length of the wall thickness change web, it is possible to achieve weight reduction while suppressing the occurrence of buckling at this part.

[0019] According to the under protector of the preceding item [5], since the rear side region, the collision surface side region, and the intermediate region are each composed of a certain wall thickness, it is possible to avoid the occurrence of stress concentration within each region.

Brief Description of the Drawings

[0020] [Figure 1] It is a side cross-sectional view showing an under protector according to an embodiment of the present invention. [Figure 2] It is a side view showing the mounting position relationship of the under protector to the vehicle. [Figure 3] It is a plan view showing the mounting position relationship of the under protector to the vehicle. [Figure 4] It is a schematic diagram of a load test on the under protector.

Modes for Carrying Out the Invention

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] FIG. 1 is a side cross-sectional view of an under protector according to an embodiment of the present invention. FIG. 2 is a side view showing the mounting position relationship of the under protector to the vehicle, and FIG. 3 is a plan view thereof.

[0023] The under protector 1 is mainly mounted on large vehicles such as trucks, and prevents a collided passenger car or the like from getting under the large vehicle.

[0024] As shown in FIGS. 2 and 3, the under protector 1 is attached so as to be positioned below the vehicle body frame 20 by brackets 2, 2 at two positions on the left and right in the vehicle width direction.

[0025] The under protector 1 according to the present invention can be applied to both a rear under protector mounted on the rear of the vehicle body and a front under protector mounted on the front of the vehicle body.

[0026] As shown in the side cross-sectional view of Figure 1, the under protector 1 according to this embodiment has a substantially rectangular outer shape.

[0027] The under protector 1 is required to be lightweight as well as having load-bearing capacity. For this reason, the under protector 1 according to this embodiment is formed from a lightweight aluminum alloy extruded material.

[0028] For the aluminum alloy material, the common 6000 series or 7000 series can be used.

[0029] The under protector 1 according to this embodiment, as shown in the side cross-sectional shape of Figure 1, comprises a rear flange 31 erected on the vehicle side, a collision surface flange 32 erected at a distance from the rear flange, an upper web 41 connecting the upper part of the rear flange 31 and the upper part of the collision surface flange 32, a lower web 42 connecting the lower part of the rear flange 31 and the collision surface flange 32, and an intermediate web 42 connecting the rear flange 31 and the collision surface flange 32 at a height position between the upper web 41 and the lower web 42.

[0030] In this embodiment, the rear flange 31 and the impact surface flange 32 have the same length (height) and are arranged parallel to each other.

[0031] The top web 41, the middle web 43, and the bottom web 42 have the same length (depth, length in the left-right direction in Figure 1), are arranged parallel to each other, and the distance between the top web 41 and the middle web 43 is the same as the distance between the middle web 43 and the bottom web 42.

[0032] In this embodiment of the underprotector 1, the upper web 41 and the lower web 42 are configured as a thickness-changing web having regions with different thicknesses.

[0033] In other words, the upper web 41 and the lower web 42 have three regions: a rear side region 51 located on the rear flange 31 side, an impact surface side region 52 located on the impact surface flange 32 side, and an intermediate region 53 located between these two regions, and the thickness of these rear side region 51, impact surface side region 52, and intermediate region 53 are all different.

[0034] The thickness t1 of the rear side region 51 is the thickest of the three regions, the thickness t3 of the intermediate region 53 is the thinnest, and the thickness t2 of the collision surface side region 52 is in between these thicknesses, resulting in the relationship t1>t2>t3.

[0035] The thinnest intermediate region 52 has a wall thickness t3 of 2 mm or more.

[0036] The wall thicknesses t1, t2, and t3 within each region 51, 52, and 53 are constant, except for a small portion at the edge of each region where the wall thickness changes continuously between adjacent regions.

[0037] The range of the rear side region 51 is defined as extending from the position corresponding to the inner surface of the rear flange 31 to the central position of the small portion where the wall thickness changes continuously between it and the intermediate region 53, and its length is shown as L1 in Figure 1.

[0038] The impact surface side region 52 extends from the position corresponding to the inner surface of the impact surface flange 32 to the central position of the small portion where the wall thickness changes continuously between it and the intermediate region 53, and its length is shown as L2 in Figure 1.

[0039] The intermediate region 53 extends from the central position of the small portion where the thickness changes continuously between it and the rear side region 51, to the central position of the small portion where the thickness changes continuously between it and the collision surface side region 52, and its length is shown as L3 in Figure 1.

[0040] The length L1 of the back side region 51 is set to 35% to 45% of the total length L (=L1+L2+L3) of the thickness-changing web.

[0041] The length L3 of the intermediate region 53 is set to 25% to 35% of the total length L of the thickness-changing web, ensuring a length of 5 mm or more.

[0042] The length L2 of the impact surface region 52 is the remaining length after the length L1 of the back surface region 51 and the length L3 of the intermediate region 53, and is 20% to 40% of the total length L of the thickness-changing web.

[0043] Figure 4 is a schematic diagram of the load test on the under protector.

[0044] The under protector is required to have a certain strength in various collision scenarios in order to prevent a passenger car from getting stuck under a large vehicle, such as a truck, when the under protector 1 is installed in a collision with the passenger car.

[0045] The under protector 1 is connected to the vehicle frame 20 via two brackets 2,2 on the left and right sides. Strength requirements are defined for loads P1 on the vehicle ends outside the bracket mounting positions, loads P2 directly above the bracket mounting positions, and loads P3 on the central part of the vehicle midway between the two bracket mounting positions.

[0046] When loads P1, P2, or P3 are applied to the underprotector 1, the underprotector 1 will buckle at one of its points at a predetermined load, and thereafter the load will decrease. The load at which this buckling occurs is the maximum load, and loads P1, P2, and P3 are required to have a predetermined maximum load.

[0047] When a vehicle equipped with Under Protector 1 collides with another vehicle, a load is applied to the collision surface flange 32 of Under Protector 1.

[0048] At this time, since the under protector 1 is supported by brackets 2,2 on the left and right sides, the load is concentrated near the area of ​​the rear flange 31 that is supported by brackets 2,2, causing the rear flange 31 to deform.

[0049] Therefore, in each web 41, 42, and 43, the deformation is greatest in the region adjacent to the rear flange 31, resulting in a high stress load in that area and a strong influence on the maximum load.

[0050] In this embodiment of the under protector 1, the upper web 41 and the lower web 42 are made of webs with varying thickness, and the area adjacent to the rear flange 31 is designated as the rear side region 51 and has the thickest thickness, thereby preventing buckling of the rear side region 51 and obtaining high load-bearing performance.

[0051] When a load is applied to the under protector 1, the stress load is high in the region from the back flange 31 to 35% to 45% of the total length of the web in each web 41, 42, and 43, making buckling likely.

[0052] In the under protector 1 according to this embodiment, the length L1 of the back side region 51 of the upper web 41 and lower web 42 is set to 35% to 45% of the total length L of the thickness-changing web, thereby preventing buckling of the back side region 51 and obtaining high load-bearing performance.

[0053] When a P2 load is applied to the under protector 1 directly above the fixing points by brackets 2,2, a load is applied near the load application point that widens the angle of the corner portion where the rear flange 31 and each web 41, 42, 43 are connected, making it prone to cracking in the inner R portion.

[0054] Similarly, when the P2 load is applied, a load is also applied to the collision surface flange 32 side in a direction that widens the angle of the corner portions connected to each web 41, 42, and 43, making it prone to cracking in the inner R portion.

[0055] On the other hand, the intermediate regions 53 of each web 41, 42, and 43 are separated from the rear flange 31 and the collision surface flange 32, and do not have corner sections, so they hardly deform, and the stress load in those areas is low.

[0056] In the underprotector 1 according to this embodiment, the upper web 41 and lower web 42 have the area adjacent to the collision surface flange 32 designated as the collision surface side region 52, ensuring a thickness second only to the rear side region 51, while the thickness of the intermediate region 53, where the stress load is low, is made the thinnest. Therefore, weight reduction can be achieved without reducing the P2 load.

[0057] While the intermediate region 53 experiences low stress loads, a larger thin-walled region may lead to buckling.

[0058] In the underprotector 1 according to this embodiment, the length of the intermediate region 53, which has the thinnest thickness, is limited to 25% to 35% of the total length of the thickness-changing web, thereby enabling weight reduction while suppressing buckling in that area.

[0059] Furthermore, by providing the thinnest portion in the intermediate region 53, minute deformation is induced in that portion, suppressing excessive deformation of the rear region 51 and reducing the load on the rear region 51. This also contributes to improving load-bearing performance.

[0060] Furthermore, in the under protector 1 according to this embodiment, a wall thickness of 2 mm or more and a length of 5 mm or more are ensured even in the thinnest intermediate region 53, thus enabling stable extrusion molding.

[0061] Furthermore, according to the underprotector 1 of this embodiment, since the back side region 51, the collision surface side region 52, and the intermediate region 53 are each composed of a constant thickness, it is possible to avoid stress concentration occurring within each region.

[0062] Thus, according to the under protector 1 of this embodiment, the upper web 41 and the lower web 42 are divided into three regions with different thicknesses as thickness-variable webs, and the thickness is set according to the influence on the strength (maximum load) in each part, thereby achieving weight reduction while obtaining high load-bearing performance.

[0063] In the above embodiment, an example was shown in which the upper web 41 and the lower web 42 were thickness-changing webs. However, it is sufficient that at least one of the upper web, intermediate web, and lower web is a thickness-changing web. It is also possible that only one of these three webs is a thickness-changing web, or that all three webs are thickness-changing webs, or that the intermediate web 43 and the upper web 41, or the intermediate web 43 and the lower web 42, are two thickness-changing webs.

[0064] Furthermore, although the above embodiment shows an example where the outside of the under protector 1 is flat, it may also have outward protrusions.

[0065] Furthermore, although the above embodiment shows an example where the outer shape of the under protector 1 is approximately rectangular, the angle between the flange and the web does not have to be 90 degrees. [Examples]

[0066] Under Protector 1 was manufactured using an aluminum alloy.

[0067] The material used was an aluminum alloy consisting of Si: 1.05 mass%, Fe: 0.20 mass%, Cu: 0.40 mass%, Mg: 0.75 mass%, Ti: 0.04 mass%, Zr: 0.15 mass%, other impurities, and aluminum.

[0068] A billet with a circular cross-section and a diameter of 370 mm was produced from this alloy by continuous casting. The obtained billet was subjected to a homogenization treatment at 570°C for 9 hours. After that, the billet was reheated to 500°C and hot extruded. A die quenching process was performed on the high-temperature material immediately after extrusion to obtain as-extruded material. The obtained as-extruded material was subjected to artificial aging treatment at 180°C for 6 hours to obtain extruded material.

[0069] The cross-sectional shape of the extruded material was set to a height of 150 mm and a width (depth) of 125 mm.

[0070] In the embodiment with a web of varying thickness, the length of the back side region was L1 = 45 mm, the length of the impact side region was L2 = 35 mm, and the length of the intermediate region was L3 = 35 mm, with the thickness of each region as shown in Table 1.

[0071] A simulation simulating a P2 load test was performed using the obtained extruded material to determine the maximum load at which buckling would occur in any part of the material. The results are shown in Table 1.

[0072] [Table 1]

[0073] The evaluation was based on Comparative Example 1, in which the thickness of all flanges and webs was 5 mm. Products that were lighter than Comparative Example 1 (17.7 kg) and capable of handling loads of 130 kN or more (similar to the load of Comparative Example 1, 132 kN) were judged as OK, while products that did not meet even one of these conditions were judged as NG.

[0074] In the embodiments of the present invention equipped with a thickness-changing web in which the thickness t1 of the back side region 51, the thickness t2 of the collision surface side region 52, and the thickness t3 of the intermediate region 53 are in the relationship t1>t2>t3, a weight reduction of 3% or more was achieved compared to Comparative Example 1, and the decrease in load compared to Comparative Example 1 was limited to 1.5% or less, demonstrating that weight reduction was achieved while obtaining high load-bearing performance. [Explanation of Symbols]

[0075] 1 Under Protector 2 brackets 20 Body frame 31 Rear flange 32 Impact surface flange 41 Top web 42 Bottom web 43 Intermediate Web 51 Back area 52 Collision surface side area 53 Intermediate area

Claims

1. An under protector made of aluminum alloy extruded material, The device comprises a rear flange erected on the vehicle side, a collision surface flange erected at a distance from the rear flange, an upper web connecting the upper part of the rear flange and the collision surface flange, a lower web connecting the lower part of the rear flange and the collision surface flange, and an intermediate web connecting the rear flange and the collision surface flange at a height between the upper web and the lower web. At least one of the upper web, the intermediate web, and the lower web comprises three regions: a rear-side region located on the rear flange side, an impact-side region located on the impact-side flange side, and an intermediate region located between these, and is configured as a thickness-variable web with different thicknesses in each of these three regions. An underprotector characterized in that, in the aforementioned thickness-variable web, the thickness of the back side region is the thickest, and the thickness of the intermediate region is the thinnest.

2. The under protector according to claim 1, wherein the thickness of the intermediate region is 2 mm or more and the length is 5 mm or more.

3. The underprotector according to claim 1 or 2, wherein the length of the back side region is 35% to 45% of the total length of the thickness-changing web.

4. The underprotector according to claim 1 or 2, wherein the length of the intermediate region is 25% to 35% of the total length of the thickness-changing web.

5. The under protector according to claim 1 or 2, wherein the rear side region, the collision surface side region, and the intermediate region are each composed of a constant thickness.

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