Fire resistance testing machine and fire resistance testing method

Abstract

This invention provides a fire resistance testing machine and fire resistance testing method that can prevent interference between the fuel pan and the screen during fire resistance testing. [Solution] The fire resistance testing machine 1 comprises a test stand 2 on which the object to be tested T is placed, a fuel pan 4 that is horizontally movable relative to the test stand 2 and on which fuel is ignited, and a screen 6 having a frame 61 and a plurality of firebricks. When the fuel pan 4 is positioned below the test stand 2, the screen 6 is movable horizontally between them and has a lifting mechanism that allows the screen 6 to be raised and lowered vertically.

Description

Technical Field

[0001] The present invention relates to a fire resistance tester and a fire resistance test method for a test object such as an in-vehicle lithium ion battery.

Background Art

[0002] In recent years, the spread of electric vehicles (BEV) and hybrid electric vehicles (HEV) has been rapidly progressing. In these vehicles, lithium ion batteries having a high energy density are widely used as power storage devices for storing power for running.

[0003] While lithium ion batteries have the advantages of being lightweight and having a high capacity, there is a risk of thermal runaway due to vibration, impact, short circuit, overcharge, heating from the outside, etc. (see, for example, Patent Document 1). For this reason, there is a strong demand for ensuring a certain level of safety for lithium ion batteries mounted on vehicles even in abnormal situations.

[0004] From such a background, "UN ECE R100" has been established as an international agreement rule for lithium ion batteries mounted on EVs, etc. This rule describes 10 tests, one of which is a fire resistance test. This fire resistance test is a test for verifying the resistance of a lithium ion battery to exposure to flames from outside the vehicle, and is intended to ensure sufficient time for the driver and passengers to evacuate even in such abnormal situations.

[0005] An outline of an example of the fire resistance test will be described using FIG. 5. This fire resistance test is composed of three stages of the following stages B to D, or four stages of stages A to D. The diagrams of stages A to D in FIG. 5 are cited from the "ECE-R100 Fire Resistance Test Specification" of the Ministry of Land, Infrastructure, Transport and Tourism. Stage A (preheating): Ignite the fuel in the fuel pan at a distance of at least 3 m from the test object, and after preheating for 60 seconds, place the fuel pan under the test object. Stage B (direct exposure to flames): Expose the test object to the flames from the freely burning fuel for 70 seconds. Stage C (Indirect Exposure to Flame): Immediately after completion of Stage B, place the screen between the burning fuel pan and the test object. Expose the test object to this reduced flame for an additional 60 seconds. Stage D (End of Test): Return the fuel pan to the position in Stage A.

[0006] In this fire resistance test, the screen comprises a steel frame and a screen body made of multiple firebricks placed on the frame. The frame has an annular frame and a frame spanning between the frame sections. The screen body is constructed by laying multiple firebricks on the frame of the frame so that there are no gaps between them. In addition, holes are formed in the firebricks that penetrate in the thickness direction. By placing the screen between the fuel pan and the object to be tested, the object to be tested is indirectly exposed to flames through its fire-resistant lens.

[0007] This fire resistance test specifies in detail the dimensions of the fuel pan and the height of the screen. In particular, the screen is specified to be placed 3 cm ± 1 cm above the fuel level (height) of the fuel pan measured before fuel ignition. Therefore, the gap between the screen stand and the fuel pan must be controlled to be small. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2024-150692 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Incidentally, during fire resistance testing, when the screen is moved, a portion of the support structure is directly exposed to the flames. As a result, areas of the support structure become locally hot while areas of relatively low temperature coexist, leading to differences in expansion. Consequently, distortion may occur in the support structure. In particular, the degree of distortion tends to increase as the screen size increases. On the other hand, as mentioned above, there is a small gap between the screen support structure and the fuel pan.

[0010] When the screen's support structure deforms in this way, the screen may interfere with the fuel pan when moving it between the fuel pan and the object under test (when moving from stage B to stage C, and when moving from stage C to stage D), potentially preventing the fire resistance test from being properly conducted.

[0011] This invention has been made in view of these circumstances, and aims to provide a fire resistance testing machine and a fire resistance testing method that can prevent interference between the fuel pan and the screen during a fire resistance test. [Means for solving the problem]

[0012] The fire resistance testing machine of the present invention comprises a test stand on which an object to be tested is placed, a fuel pan that is horizontally movable relative to the test stand and on which fuel is ignited, and a screen having a frame and a plurality of firebricks, wherein the fire resistance testing machine has a lifting mechanism that allows the screen to be moved horizontally between the test stand and the fuel pan when the fuel pan is positioned below the test stand, and that allows the screen to be raised and lowered vertically.

[0013] In one configuration, the lifting mechanism has a lifting cylinder, which is positioned between the upper surface of the screen trolley that moves the screen and the screen's mounting base.

[0014] Furthermore, the frame is supported by the lifting cylinder at a height higher than the height of the lower surface of the frame. In other words, the height of the support surface of the frame supported by the lifting cylinder is higher than the height of the lower surface of the frame.

[0015] Furthermore, multiple lifting cylinders are arranged on each side in relation to the direction of movement of the screen. In addition, the lifting cylinders are air cylinders connected to an air supply device and an air supply pipe, and the air supply pipe extends from the rear side to the front side of the screen and is connected to the air cylinder by folding back at the front end.

[0016] Furthermore, the screen described above has a width dimension perpendicular to the direction of movement of the screen, for example, approximately 1000 mm to 3500 mm.

[0017] The present invention provides a fire resistance testing method that uses a fire resistance testing machine comprising a test stand on which an object to be tested is placed, a fuel pan that is horizontally movable relative to the test stand and on which fuel is ignited, and a screen having a frame and a plurality of firebricks, wherein the fire resistance testing method comprises a direct exposure step in which the object to be tested is directly exposed to the flame with the fuel pan positioned below the test stand, and an indirect exposure step in which the object to be tested is indirectly exposed to the flame with the screen positioned between the test stand and the fuel pan, characterized in that, before the indirect exposure step, the screen is raised and moved horizontally toward the fuel pan, and then the screen is lowered so that the screen is positioned between the test stand and the fuel pan. [Effects of the Invention]

[0018] The fire resistance testing machine of the present invention has a lifting mechanism that allows the screen to be moved horizontally between the fuel pan and the test stand when the fuel pan is positioned below the test stand, and also allows the screen to be raised and lowered vertically. This prevents interference between the fuel pan and the screen that may occur when the screen is moved, and allows the fire resistance test to be performed properly.

[0019] In the above-mentioned lifting mechanism, which has a lifting cylinder positioned between the upper surface of the screen trolley that moves the screen and the screen stand, if the stand is supported by the lifting cylinder at a position higher than the height of the lower surface of the stand, it is easier to stabilize the movement of the screen when lifting a heavy screen, and also easier to stabilize the lifting by the cylinder.

[0020] Furthermore, the lifting cylinder is an air cylinder connected to an air supply device and an air supply pipe. In a configuration where the air supply pipe extends from the rear to the front of the screen and folds back at the front end before connecting to the air cylinder, the air supply device can be fixed in place. By folding back the air supply pipe to create slack, it is possible to prevent the air supply pipe from becoming taut when the screen moves, and to smoothly supply air to the air cylinder. The same applies to hydraulic and electric cylinders.

[0021] Furthermore, in configurations where the screen has a large width dimension perpendicular to the direction of movement of the screen, deformation due to distortion of the frame becomes a greater concern. However, by using the above-described lifting mechanism, interference between the fuel pan and the screen can be prevented, and tests can be carried out smoothly even with large test objects.

[0022] The fire resistance test method of the present invention is a method using a fire resistance testing machine and comprises a direct exposure step in which the object to be tested is directly exposed to the flame with a fuel pan placed below the test stand, and an indirect exposure step in which the object to be tested is indirectly exposed to the flame with a screen placed between the test stand and the fuel pan. Before the indirect exposure step, the screen is raised and moved horizontally toward the fuel pan, and then lowered so that the screen is placed between the test stand and the fuel pan. This prevents interference between the fuel pan and the screen that may occur when the screen is moved in conventional fire resistance test methods, and allows the fire resistance test to be properly conducted. [Brief explanation of the drawing]

[0023] [Figure 1] It is a schematic plan view showing an example of the fire resistance testing machine of the present invention. [Figure 2] It is an enlarged view of the screen of the fire resistance testing machine in FIG. 1. [Figure 3] It is a diagram for explaining the outline of the fire resistance testing machine of the present invention. [Figure 4] It is a diagram for explaining the lifting mechanism in the fire resistance testing machine in FIG. 1. [Figure 5] It is a diagram for explaining the general flow of the fire resistance testing method.

Embodiments for Carrying Out the Invention

[0024] The fire resistance testing machine of the present invention is a testing machine used for the fire resistance test of a test object. Examples of the test object include various lithium-ion batteries mounted on vehicles (such as BEV, PHEV, HEV, etc.).

[0025] An example of the fire resistance testing machine of the present invention will be described based on FIG. 1. FIG. 1 is a schematic plan view of the fire resistance testing machine and shows the arrangement state before the start of the fire resistance test. The fire resistance testing machine 1 has an overall planar shape that is a rectangular shape elongated in one direction (the X-axis direction). In FIG. 1, the X-axis direction and the Y-axis direction are perpendicular to each other.

[0026] As shown in FIG. 1, the fire resistance testing machine 1 mainly includes a test bench 2 for placing the test object T, a fuel pan 4, and a screen 6. The test bench 2, the fuel pan 4, and the screen 6 each have a rectangular planar shape. In FIG. 1, the test bench 2 is arranged in the center, the fuel pan 4 is arranged on one side thereof, and the screen 6 is arranged on the other side. In the state before the test, the test bench 2, the fuel pan 4, and the screen 6 are arranged so as not to overlap each other in the vertical direction.

[0027] In Figure 1, the test stand 2, fuel pan 4, and screen 6 are each movable in the X-axis direction. Specifically, the test stand 2 is mounted on a test stand trolley 3, which moves horizontally with the test stand 2 along a pair of rails R2 extending in the X-axis direction. The fuel pan 4 is mounted on a fuel pan trolley 5, which moves horizontally with the fuel pan 4 along a pair of rails R4 extending in the X-axis direction. The screen 6 is mounted on a screen trolley 7, which moves horizontally with the screen 6 along a pair of rails R6 extending in the X-axis direction.

[0028] Each of the trolleys 3, 5, and 7 has a metal base and wheel section and is strong enough to withstand the weight of the test stand 2, fuel pan 4, screen 6, etc.

[0029] In Figure 1, each rail R2, R4, and R6 is composed of a chain, and the movement of this chain causes the trolley on that rail to move. Each rail R2, R4, and R6 is connected to a drive shaft S at one end in the X-axis direction. Each drive shaft S extends along the Y-axis direction and is rotatable by a motor M connected to it. For example, when the motor M for rail R2 is driven, the drive shaft S connected to it rotates, and the chain connected to the drive shaft S moves, causing the test trolley 3 and the test stand 2 on rail R2 to move.

[0030] In Figure 1, the rail widths of each rail R2, R4, and R6 are as follows: the rail width of test stand 2 is the widest, followed by the rail width of screen 6, and then the rail width of fuel pan 4 (R2 > R6 > R4). In fire resistance testing machine 1, each motor M is located outside of screen 6, that is, away from fuel pan 4. In fire resistance testing machine 1, each part is directly exposed to flames and is in a harsh environment with high temperatures, so the motors M are positioned as far away from the flames as possible.

[0031] Furthermore, the mechanism for moving the test stand 2, fuel pan 4, and screen 6 can employ any known moving mechanism as appropriate, and is not limited to chain drive. In addition, in the fire resistance testing machine 1 of the present invention, it is sufficient that at least the screen 6 is movable horizontally, and either the test stand 2 or the fuel pan 4 may be immovable, i.e., fixed. In that case, the test stand trolley 3 or the fuel pan trolley 5 and their corresponding motors can be omitted, and for example, the test stand 2 or the fuel pan 4 can be fixed to the base frame of the fire resistance testing machine 1.

[0032] As shown in Figure 1, the test stand 2 has a horizontally extending wire mesh 21. The object to be tested T is placed on this wire mesh 21. The size of the wire mesh 21 (length L2, width W2) should be large enough to accommodate the object to be tested T with ample clearance in the X-axis and Y-axis directions. Generally, the length L2 is about 1000mm to 3500mm, and the width W2 is about 1000mm to 3500mm. For example, if the object to be tested T is a relatively large lithium-ion battery for a BEV, the length L2 is about 2500mm to 3500mm, and the width W2 is about 2500mm to 3500mm.

[0033] The fuel pan 4 is a metal container for holding fuel such as oil. The fuel pan 4 has a rectangular bottom and a peripheral wall that rises from the periphery of the bottom, and holds the fuel inside. Before the start of the fire resistance test, the fuel is poured into the fuel pan 4, and the height of the oil level of the poured fuel becomes the fuel level and the reference for dimensional control. When the fuel is ignited at the start of the test, a flame is generated. The size (length, width) of the fuel pan 4 is, for example, slightly larger than the screen 6 in the X and Y directions, and slightly smaller than the wire mesh 21 in the X and Y directions.

[0034] The screen 6 comprises a steel frame 61 and a plate-shaped screen body 62 made of multiple firebricks installed on the frame 61. This screen 6 will be explained in detail with reference to Figure 2. Figure 2 shows a schematic plan view of the screen (mainly the frame) and the screen trolley before the firebricks are laid.

[0035] As shown in Figure 2, the frame 61 of the screen 6 is composed of multiple frames. The frame 61 has a rectangular frame section 61a and multiple bottom frames 61b that are spanned between the frame sections 61a. The frame section 61a is composed of a pair of vertical frame sections arranged along the vertical direction (Y-axis direction) and a pair of horizontal frame sections arranged along the horizontal direction (X-axis direction), which are connected together. The vertical and horizontal frame sections are made of steel (e.g., H-beams) and are long members with a thickness of about 4 to 20 mm.

[0036] The bottom frame 61b is a flat steel plate with a thickness of approximately 3 to 20 mm, and in Figure 2, it extends along the Y-axis. The bottom frame 61b may also be configured to extend along the X-axis, or to extend in both the Y-axis and X-axis directions. The number and width of the bottom frame 61b are determined according to the size of the firebricks placed on top of it.

[0037] In Figure 2, the frame portion 61a is erected relative to the bottom frame 61b, and the interior of the support structure 61 forms a frame structure that constitutes the housing for the screen body. The screen body is constructed by laying multiple firebricks 62a across the bottom frame 61b of the support structure 61 in the X-axis and Y-axis directions.

[0038] The length L6 and width W6 of the screen body are not particularly limited, but for example, if the object T under test is relatively large, the length L6 is approximately 2000mm to 3000mm and the width W6 is approximately 2000mm to 3000mm. In this case, the width of the screen 6 will be 2000mm or more, making it more susceptible to deformation due to heat, etc.

[0039] As shown in Figure 2, the firebricks 62a are block bodies with circular holes formed through them in the thickness direction. These firebricks 62a are arranged so as to straddle the bottom frame 61b. The number and diameter of the circular holes in the firebricks 62a, the distance between the circular holes, and the dimensions of each brick are standardized, and firebricks that conform to the specified standards are used. Note that the firebricks shown in Figure 2 are just one example.

[0040] A screen constructed of refractory bricks is used for indirect exposure in fire resistance tests. Specifically, the screen is moved horizontally between fuel pans placed below the test stand and positioned between them, thereby indirectly exposing the test object to flames through the refractory lens 62a.

[0041] Here, we will explain the outline of the fire resistance testing machine of the present invention using Figure 3. In Figure 3, for convenience, the height positions of each part of the fire resistance testing machine are labeled A, B, C, and D from top to bottom. Height position A indicates the height of the lower surface of the screen after it has been raised, height position B indicates the height of the lower surface of the screen at the reference time (before raising or after lowering), height position C indicates the height of the upper end of the fuel pan, and height position D indicates the height of the fuel in the fuel pan. The lower surface of the screen is composed of the lower surface of the support structure (the lower surface of the frame or the lower surface of the bottom frame), and indicates the lowest height position of the screen. In addition, although the test stand is not shown in Figure 3, it is assumed that the test stand is located above the fuel pan.

[0042] Figure 3(a) shows the screen before it is moved. The fire resistance test standard specifies that the screen should be placed 3 cm ± 1 cm above the fuel height position D in the fuel pan, and it is necessary to control the Δt between height positions BD with a small gap. On the other hand, repeated fire resistance tests may cause deformation such as distortion of the screen frame, and this deformation may cause the height position of a part of the frame to drop, potentially interfering with the top of the fuel pan (height position C).

[0043] In contrast, the fire resistance testing machine of the present invention is equipped with a lifting mechanism that raises and lowers the screen vertically, thereby preventing such interference. Specifically, before moving the screen, the lower surface of the screen is raised to height position A by the lifting mechanism (Figure 3(b)). Then, after moving the screen above the fuel pan with the screen raised (Figure 3(c)), the lower surface of the screen is lowered to height position B (Figure 3(d)). This makes it possible to prevent interference between the screen and the fuel pan while controlling the Δt between height positions B and D.

[0044] The distance the lifting mechanism raises the object (the difference between height position A and height position B) is not particularly limited, but for example, it is between 10mm and 50mm.

[0045] Furthermore, the lifting mechanism can also be used when returning the screen to its initial position after indirect exposure is complete. Specifically, the lower surface of the screen is raised to height position A using the lifting mechanism (Figure 3(c)), then the screen is moved back to its initial position in the raised position (Figure 3(b)), and finally the lower surface of the screen is lowered to height position B (Figure 3(a)). In this way, interference with the fuel pan can be prevented when returning the screen.

[0046] The lifting mechanism will now be explained in detail. In the configuration shown in Figure 2, a lifting cylinder (not shown) is used as the lifting mechanism. The lifting cylinder is positioned between the upper surface 71 of the frame of the screen trolley 7 that moves the screen 6 and the screen stand 61 of the screen 6. More specifically, the horizontal frame of the frame portion 61a of the stand 61 has multiple support portions 61c that partially protrude outwards, and the lifting cylinder is positioned below these support portions 61c.

[0047] In Figure 2, the frame 61 has four support sections 61c on each side in the direction of movement of the screen 6 (X2 direction). Accordingly, four lifting cylinders are also arranged on each side in the direction of movement of the screen 6. The number of lifting cylinders is not particularly limited, but in order to raise and lower the heavy screen 6 while keeping it flat, it is preferable to provide multiple cylinders on each side in the direction of movement of the screen 6.

[0048] The lifting cylinder uses compressed fluid to move a piston in a straight line, and can use, for example, an air cylinder or a hydraulic cylinder. However, considering safety, an air cylinder is preferable. In the following explanation, the lifting cylinder will be described as an air cylinder.

[0049] The air cylinder is connected to an air supply device 9 and an air supply pipe 91. The air supply pipe 91 and other components are installed covered with fire-resistant materials such as fire-resistant wool. The air supply device 9 is mounted, for example, outside the screen 6 and outside the base frame of the fire resistance testing machine. From this air supply device 9, air supply pipes 91 are connected to the screen 6 from the rear on both the left and right sides. The side of the screen 6 closer to the fuel pan is considered the front side, and the side further away is considered the rear side. A more specific connection configuration is shown in Figure 4.

[0050] Figure 4(a) shows a schematic diagram of the screen and screen trolley viewed from the side. The base frame of the screen trolley 7 extends along the X-axis direction, and the lifting cylinders 8 are positioned on its upper surface 71. The lifting cylinders 8 are spaced apart from each other and arranged in a straight line along the X-axis direction.

[0051] As shown in Figure 4(a), the air supply pipe 91 extends from the rear side of the screen 6 toward the front side and is connected to the air cylinder by folding back at the front end of the screen 6. The air supply pipe 91 has a folded portion 91a formed by folding back from the bottom to the top. The air supply pipe 91 is connected to each of the lifting cylinders 8. The screen 6 will move toward the front side (towards the side indicated by the white arrow in the figure), and the air supply pipe 91 is connected in such a way that it has sufficient slack to account for this movement distance.

[0052] As shown in the enlarged view of Figure 4(b), the support portion 61c is constructed with a U-shaped steel member facing downwards. The lifting cylinder 8 is installed in a direction in which the piston 81 moves up and down, and the upper end surface of the piston 81 is in contact with the support portion 61c. The surface on which this support portion 61c contacts the piston 81 is called the support surface 61d. The height position of this support surface 61d on the frame 61 is higher than the height position of the lower surface 61e of the frame 61 (which is also the lower surface of the screen). In other words, the screen 6 is supported by the lifting cylinder 8 at a height position higher than the lower surface 61e of the frame 61.

[0053] When the screen is raised, compressed air is supplied from the air supply device to the lifting cylinder 8 via the air supply pipe, causing the piston 81 to rise and the entire screen to lift. As a result, the height of the lower surface 61e of the screen is raised, and a larger gap can be secured between it and the upper end of the fuel pan.

[0054] Supporting the screen in this way makes it easier to stabilize the movement of the screen when raising or lowering a heavy screen, and also makes it easier to stabilize the raising and lowering by the lifting cylinder 8.

[0055] The fire resistance testing machine has been described above using Figures 1 to 4, but the fire resistance testing machine of the present invention is not limited to the above configuration. For example, the lifting mechanism is not limited to a lifting cylinder, and other lifting mechanisms can be used.

[0056] Furthermore, the fire resistance test method of the present invention will be explained with reference to Figure 1. The fire resistance test method uses a fire resistance testing machine 1 which comprises a test stand 2 on which the object to be tested T is placed, a fuel pan 4 that is horizontally movable relative to the test stand 2 and on which fuel is ignited, and a screen 6 having a frame 61 and a plurality of firebricks.

[0057] This method includes a direct exposure step in which the fuel in the fuel pan 4 is ignited to generate a flame, the fuel pan 4 is moved in the X1 direction and positioned below the test stand 2, and the test object T is directly exposed to the flame for a predetermined time; a screen placement step in which the screen 6 is raised and moved horizontally toward the fuel pan 4, and then the screen 6 is lowered to position the screen 6 between the test stand 2 and the fuel pan 4; and an indirect exposure step in which the test object T is indirectly exposed to the flame for a predetermined time with the screen 6 positioned between the test stand 2 and the fuel pan 4. [Industrial applicability]

[0058] The fire resistance testing machine of the present invention can prevent interference between the fuel pan and the screen during fire resistance testing, allowing for stable fire resistance testing even when the test object is large or when the fire resistance testing machine is used repeatedly over a long period of time. Furthermore, it can be used widely without limitations on the test object. [Explanation of Symbols]

[0059] 1. Fire resistance testing machine 2 Test benches 21 Wire mesh 3 Test trolley 4 Fuel Pan 5 Fuel pan trolley 6 screens 61 mounting base 62 Screen Unit 62a Firebrick 7 Screen Cart 71 Top surface 8. Lifting cylinder 81 Piston 9. Air supply device 91 Air supply pipe M Motor R2, R4, R6 rails S drive shaft T Test object

Claims

1. A fire resistance testing machine comprising a test stand on which an object to be tested is placed, a fuel pan that is horizontally movable relative to the test stand and on which fuel is ignited, and a screen having a frame and a plurality of firebricks, The fire resistance testing machine is characterized in that, with the fuel pan positioned below the test stand, the screen is movable horizontally between them, and the machine has a lifting mechanism that allows the screen to be raised and lowered vertically.

2. The fire resistance testing machine according to claim 1, characterized in that the lifting mechanism has a lifting cylinder, and the lifting cylinder is positioned between the upper surface of the screen trolley that moves the screen and the frame of the screen.

3. The fire resistance testing machine according to claim 2, characterized in that the frame is supported by the lifting cylinder at a position higher than the height of the lower surface of the frame.

4. The fire resistance testing machine according to claim 2 or 3, characterized in that multiple lifting cylinders are arranged on each side with respect to the direction of movement of the screen.

5. The fire resistance testing machine according to claim 2 or 3, characterized in that the lifting cylinder is an air cylinder connected to an air supply device and an air supply pipe, and the air supply pipe extends from the rear side to the front side of the screen and is connected to the air cylinder by folding back at the front end.

6. A fire resistance test method using a fire resistance testing machine comprising a test stand on which an object to be tested is placed, a fuel pan that is horizontally movable relative to the test stand and on which fuel is ignited, and a screen having a frame and a plurality of firebricks, The fire resistance test method is characterized by comprising: a direct exposure step of directly exposing the object to be tested to flames with the fuel pan positioned below the test stand; a screen positioning step of raising the screen, moving it horizontally toward the fuel pan, and then lowering the screen to position it between the test stand and the fuel pan; and an indirect exposure step of indirectly exposing the object to flames with the screen positioned between the test stand and the fuel pan.

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