A test method for evaluating the anti-collision capability of battery pack bottom

Abstract

The present invention relates to the field of battery pack testing, and specifically to a method for evaluating the anti-collision ability of the bottom of a battery pack, comprising the following steps: A. Battery pack pretreatment: measuring the voltage and insulation resistance of the battery pack; B. Test sample preparation: fixing the battery pack on a lifting platform, determining the position of the weak point of the collision at the bottom of the battery pack and marking it on the bottom of the battery pack, and randomly selecting the collision point if there is no obvious weak point; C. Collision equipment preparation: connecting the punch to the collision equipment; D. Bottom collision test: adjusting the position of the punch, driving the cylinder to drive the punch upward after starting the test, and the punch collides with the bottom of the battery pack; E. Standing observation: the battery pack after the collision is standing for more than 120 minutes to observe whether there is smoke, fire, etc.; F. Safety inspection after the test: measuring the voltage and insulation resistance of the battery pack, and performing a sealing performance test. This scheme can verify whether the design of the bottom protection structure of the battery pack meets the design requirements.

Description

Technical Field

[0001] The present invention relates to the field of battery pack testing, and in particular to a test method for evaluating the anti-collision capability of a battery pack bottom. Background Art

[0002] Power batteries are the core components of electric vehicles, and their safety is directly related to the safety of the entire vehicle. Failure of power batteries may lead to thermal runaway or even fire accidents. The battery pack of electric vehicles is usually installed at the bottom of the vehicle. In actual use, when the wheels pass over pits, protrusions or stone roads, the bottom of the battery pack is very susceptible to impact and scratches. If the structural strength is insufficient, it is very likely to cause safety hazards. The mechanical reliability test and evaluation methods for battery packs mainly include vibration, mechanical shock, simulated collision and extrusion methods. Among them, the extrusion test and simulated collision are mainly based on GB / T31467.3-2015 or GB 38031-2020 and some domestic and foreign enterprise standards. The battery pack is subjected to simulated collision tests. GB / T31498-2015 stipulates the safety requirements for electric vehicles after collision. However, there is currently a lack of collision test methods for the Z direction of the bottom of the vehicle or battery pack. In order to verify whether the anti-collision strength of the battery bottom meets the design requirements, it is necessary to study the battery bottom impact method. Summary of the invention

[0003] The present invention aims to provide a test method for evaluating the anti-collision capability of the bottom of a battery pack, so as to verify whether the design of the protective structure at the bottom of the battery pack meets the design requirements.

[0004] To achieve the above object, the present invention adopts the following technical solution: A battery pack bottom anti-collision ability evaluation test method, comprising the following steps:

[0005] A. Battery pack pretreatment: measure the voltage and insulation resistance of the battery pack. The insulation resistance value should be ≥100Ω / V. Adjust the SOC state of the battery through the charging equipment.

[0006] B. Test sample preparation: Fix the battery pack after adjusting the SOC on the lifting platform, determine the location of the weak point of the battery pack bottom collision according to the bottom structure of the battery pack and mark it on the bottom of the battery pack. If there is no obvious weak point, randomly select the collision point;

[0007] C. Preparation of collision equipment: Select a punch that meets the requirements, connect the punch to the collision equipment, and perform functional debugging;

[0008] D. Bottom collision test: adjust the punch position on the collision equipment so that the punch corresponds vertically to the marked position on the bottom of the battery pack. Set the collision energy according to the test conditions. The collision energy can be continuously adjusted between 20-500J. After starting the test, drive the cylinder to drive the punch upward, and the punch collides with the bottom of the battery pack.

[0009] E. Stand still for observation: After the collision, the battery pack should be left still for more than 120 minutes to observe whether there is any smoke or fire.

[0010] F. Safety check after the test: Measure the voltage and insulation resistance of the battery pack. When the insulation resistance value is ≥100Ω / V, perform a sealing performance test. If the airtightness requirements are met, the test passes.

[0011] The principle and advantage of this scheme are as follows: during the collision test on the bottom of the battery pack, the battery pack is lifted up by a lifting platform and fixed on the lifting platform, and then the collision equipment is placed under the battery pack. The collision equipment drives the punch to move upward quickly and impact the bottom of the battery pack, thereby realizing the collision of the bottom of the battery pack and simulating the collision in the Z direction of the bottom of the battery pack. It can evaluate whether the structural strength of the bottom of the battery pack meets the design requirements of the anti-collision capacity, and provide a new set of methods and processes for the anti-collision capacity test of the bottom of the battery pack. According to this method, the actual collision conditions of the bottom of the car can be simulated to evaluate the mechanical safety performance of the product.

[0012] Preferably, as an improvement, in step A, the state of charge of the battery pack is adjusted within the range of 0%-100%. Thus, by adjusting the state of charge of the battery pack, collision tests can be performed on battery packs with different states of charge.

[0013] Preferably, as an improvement, in step B, it is necessary to determine whether the battery pack has a liquid cooling system, and if so, the battery pack is filled with coolant and sealed. Thus, a collision test is performed on a battery pack with coolant.

[0014] Preferably, as an improvement, the punch can be hemispherical, mushroom-shaped or square; the punch is made of steel, copper or concrete. Thus, punches of different shapes and materials can be selected according to different test requirements.

[0015] Preferably, as an improvement, in step D, the test information includes: collision energy, collision time, collision deformation and collision force.

[0016] Preferably, as an improvement, the collision device includes a shell and a driving cylinder for driving the punch to impact, and the driving cylinder is connected to an air source; a vertical sliding rod is fixedly connected to the shell, a sliding block is vertically slidably connected to the sliding rod, the punch is detachably connected to the sliding block, and the sliding block is connected to the cylinder rod of the driving cylinder.

[0017] Thus, the driving cylinder drives the sliding block to slide on the sliding rod, and the sliding block drives the punch to collide and impact the bottom of the battery pack. The setting of the sliding rod can guide the vertical movement of the sliding block, thereby limiting the collision and impact path of the punch.

[0018] Preferably, as an improvement, an anti-backlash elastic stopper is rotatably connected to the shell, the free end of the anti-backlash elastic stopper is tilted downward, the anti-backlash elastic stopper is elastic, and the free end of the anti-backlash elastic stopper can be against the sliding block.

[0019] In this scheme, the punch is driven by the driving cylinder to collide with the bottom of the battery pack. After the driving cylinder drives the punch to move upward to collide with the bottom of the battery pack for the first time, the punch will be bounced back by the bottom of the battery pack and move downward. At the same time, the gas inside the driving cylinder is not discharged so quickly, so the piston in the driving cylinder will still bounce upward after moving downward and move upward. The piston reciprocates in the driving cylinder, and the punch will bounce up and down several times under the action of external impact force before stopping. In this way, the punch will cause multiple impacts on the bottom of the battery pack, and the impact effect of the test under the preset impact force and impact speed of the punch cannot be achieved.

[0020] In this solution, after the punch hits the bottom of the battery pack, it bounces back downwards. During the downward movement of the sliding block, it contacts the anti-rebound elastic block. The anti-rebound elastic block reduces the kinetic energy of the sliding block moving downwards. At the same time, because the anti-rebound elastic block is elastic, the anti-rebound elastic block bends downwards under the push of the sliding block. The anti-rebound elastic block does not block the sliding block from moving downwards, and the sliding block moves downwards to the bottom of the anti-rebound elastic block. After the sliding block moves downwards to the limit position, the sliding block will still bounce upwards. At this time, the anti-rebound elastic block continues to block the upward movement of the sliding block. The sliding block with reduced kinetic energy stops under the blockage of the anti-rebound elastic block, thereby preventing the punch from moving upwards and hitting the bottom of the battery pack for a second time, which is conducive to achieving the impact effect of the punch on the bottom of the battery pack under the preset impact force and impact speed.

[0021] The anti-backlash elastic block in the present solution is tilted downward and has a certain elasticity, so that when the sliding block moves downward, the anti-backlash elastic block can bend downward so that the sliding block can smoothly move downward to the bottom of the anti-backlash elastic block, avoiding the anti-backlash elastic block from being unable to bend smoothly and blocking the sliding block, so that the sliding block directly bounces upward to hit the bottom of the battery pack after colliding with the anti-backlash elastic block. In addition, the anti-backlash elastic block is tilted, so that when the sliding block moves to the bottom of the anti-backlash elastic block and then bounces upward, compared with the anti-backlash elastic block bending downward, the anti-backlash elastic block is not easy to bend upward significantly, thereby ensuring the blocking effect on the sliding block, avoiding the anti-backlash elastic block from bending upward significantly so that the sliding block rushes out of the anti-backlash elastic block and hits the bottom of the battery pack.

[0022] In addition, since the anti-backlash elastic block is rotatably connected to the shell, when the sliding block rebounds from the bottom of the anti-backlash elastic block and moves upward, when the anti-backlash elastic block contacts the sliding block, the anti-backlash elastic block swings upward to a certain extent under the push of the sliding block, thereby avoiding a hard collision between the anti-backlash elastic block and the sliding block, having a certain buffering effect on the upward movement of the sliding block, reducing the frontal impact on the sliding block and the anti-backlash elastic block, and helping to increase the service life of the sliding block and the anti-backlash elastic block.

[0023] Preferably, as an improvement, a buffer is installed on the shell, and the buffer includes a shell, a rotating shaft, a driving gear and a driven gear. The driving gear is coaxially fixedly connected to the rotating shaft, the driven gear is meshed with the driving gear, the driven gear and the rotating shaft are both rotatably connected in the shell, and a torsion spring is connected between the driven gear and the shell; the rotating shaft and the anti-rebound elastic block are fixedly connected. Therefore, when the sliding block rebounds from the bottom of the anti-rebound elastic block and moves upward, the anti-rebound elastic block swings to a certain extent under the push of the sliding block, the anti-rebound elastic block drives the rotating shaft to rotate, the rotating shaft drives the driving gear to rotate, the driving gear drives the driven gear to rotate, and the driven gear rotates to store force in the torsion spring, so that when the sliding block stops moving upward and retreats downward, the driven gear rotates in the opposite direction under the action of the torsion spring, the driven gear drives the driving gear to rotate in the opposite direction, and the driving gear drives the anti-rebound elastic block to swing through the rotating shaft and resets to the initial tilted downward state. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the battery pack bottom collision test.

[0025] Figure 2 This is a schematic diagram of the structure of the collision device.

[0026] Figure 3 This is a schematic diagram of the structure of the anti-backlash elastic stopper, sliding block and punch.

[0027] Figure 4 A cross-sectional view of the buffer. DETAILED DESCRIPTION

[0028] The following is further described in detail through specific implementation methods:

[0029] The figure marks in the drawings of the specification include: battery pack 1, punch 2, collision device 3, lifting platform 4, ground 5, limit plate 6, slide rod 7, acceleration sensor 8, buffer 9, sliding block 10, shell 11, anti-rebound elastic stopper 12, driven gear 13, driving gear 14, torsion spring 15, rotating shaft 16, fixing part 17.

[0030] The embodiment is basically as shown in the attached Figure 1-Figure 4 As shown: A battery pack bottom anti-collision ability evaluation test method, comprising the following steps:

[0031] A. Pretreatment of battery pack 1: measure the voltage and insulation resistance of battery pack 1, the insulation resistance value is ≥100Ω / V, and adjust the SOC state of the battery through the charging equipment; the charge state of battery pack 1 is adjusted within the range of 0%-100%.

[0032] B. Test sample preparation: It is necessary to determine whether the battery pack 1 has a liquid cooling system. If it has a liquid cooling system, fill the battery pack 1 with coolant and seal it. Fix the battery pack 1 after adjusting the SOC on the lifting platform 4 through the fixing member 17 (the fixing member 17 can be a fixing belt or a fixing frame), determine the position of the weak point of the collision at the bottom of the battery pack 1 according to the bottom structure of the battery pack 1 and mark it on the bottom of the battery pack 1. If there is no obvious weak point, randomly select the collision point.

[0033] C. Preparation of collision device 3: Select a punch 2 that meets the requirements, connect the punch 2 to the collision device 3, and perform functional debugging; the punch 2 can be hemispherical, mushroom-shaped or square; the punch 2 is made of steel, copper or concrete.

[0034] D. Bottom collision test: adjust the position of the punch 2 on the collision device 3 so that the punch 2 corresponds vertically to the marked position on the bottom of the battery pack 1, set the collision energy according to the test conditions, and the collision energy can be continuously adjusted between 20-500J; after starting the test, drive the cylinder to drive the punch 2 to move upward, and the punch 2 collides with the bottom of the battery pack 1; the test information includes: collision energy, collision time, collision deformation and collision force.

[0035] E. Stand still for observation: After the collision, the battery pack 1 is left to stand for more than 120 minutes to observe whether there is any smoke or fire.

[0036] F. Safety check after the test: Measure the voltage and insulation resistance of the battery pack 1. When the insulation resistance value is ≥100Ω / V, perform a sealing performance test. If the airtightness requirements are met, the test passes.

[0037] The collision device 3 in this embodiment is provided with rolling wheels on the bottom, so that the collision device 3 can move on the ground 5. The collision device includes a housing 11 and a driving cylinder for driving the punch 2 to impact, and the driving cylinder is connected to an air source. The air source is a pressure tank, and the pressure tank is connected to a pressure sensor, so that the air pressure in the pressure tank can be detected, which is convenient for adjusting the air pressure in the pressure tank.

[0038] Two vertical slide bars 7 are welded on the housing 11 or fixedly connected by screws or bolts, and a slide block 10 is vertically slidably connected to the slide bar 7. The specific sliding method is: vertical through holes are provided on the left and right ends of the slide block 10, and the slide bar 7 passes through the vertical through holes. The punch 2 is detachably connected to the upper side of the slide block 10 by screws or bolts, and the slide block 10 and the cylinder rod of the driving cylinder are connected or clamped by bolts. An acceleration sensor 8 is installed on the slide block 10, so that the moving speed of the slide block 10 can be detected. A limit plate 6 is installed on the top of the slide bar 7 by bolting or welding.

[0039] The housing 11 is rotatably connected with an anti-rebound elastic stopper 12, the free end of which is tilted downward, and is elastic. The anti-rebound elastic stopper 12 can be made of resin, rubber or other materials, and the free end of the anti-rebound elastic stopper 12 can abut against the upper and lower sides of the sliding block 10. The housing 11 is provided with a buffer 9 by bolts, and the buffer 9 is provided by the housing 11. Figure 4 As shown, the buffer 9 includes a housing, a rotating shaft 16, a driving gear 14 and a driven gear 13. The rotating shaft 16 is rotatably connected in the housing through a bearing, the driving gear 14 is coaxially fixedly connected to the rotating shaft 16 through a flat key, the driven gear 13 is meshed with the driving gear 14, and the gear shaft of the driven gear 13 is rotatably connected in the housing through a bearing. A torsion spring 15 is connected between the driven gear 13 and the housing; the rotating shaft 16 and the anti-recoil elastic block 12 are fixedly connected by screws.

[0040] The specific implementation process is as follows: lift the battery pack 1 upwards by the lifting platform 4, lift the battery pack 1 to a certain height, and then place the collision device 3 under the battery pack 1. Initially, the sliding block 10 is located below the anti-rebound elastic block 12. At this time, the end of the anti-rebound elastic block 12 is manually bent downward, and the end of the anti-rebound elastic block 12 is bent downward. The anti-rebound elastic block 12 will not block the upward movement of the sliding block 10. Then start the driving cylinder, and the air source fills the driving cylinder with gas. The driving cylinder drives the sliding block 10 to move upward along the slide rod 7. The sliding block 10 drives the punch 2 to move upward quickly and impact the bottom of the battery pack 1, thereby realizing a collision with the bottom of the battery pack 1 and simulating a collision in the Z direction on the bottom of the battery pack 1.

[0041] After the punch 2 is launched upward, the anti-rebound elastic stopper 12 is released, and the anti-rebound elastic stopper 12 is reset to the position as shown in FIG. Figure 3 In the inclined state shown, the punch 2 hits the bottom of the battery pack 1 and then bounces back downward. The sliding block 10 resists against the anti-recoil elastic block 12 during its downward movement. The anti-recoil elastic block 12 initially reduces the kinetic energy of the sliding block 10 moving downward. At the same time, since the anti-recoil elastic block 12 is elastic, the anti-recoil elastic block 12 bends downward under the push of the sliding block 10. The anti-recoil elastic block 12 will not hinder the downward movement of the sliding block 10, and the sliding block 10 moves downward to below the anti-recoil elastic block 12.

[0042] Since the speed at which the gas inside the driving cylinder is discharged is not that fast during the downward movement of the sliding block 10, the piston in the driving cylinder will still eject upward and move upward after moving downward to the limit position. Therefore, after the sliding block 10 in this embodiment moves downward to the limit position, it will still eject upward. At this time, the anti-recoil elastic block 12 continues to hinder the upward movement of the sliding block 10. The sliding block 10 stops under the obstruction of the anti-recoil elastic block 12, thereby preventing the punch 2 from moving upward and causing a secondary impact on the bottom of the battery pack 1, which is beneficial for the test to achieve the impact effect under the preset impact force and impact speed of the punch 2 on the bottom of the battery pack 1.

[0043] At the same time, since the anti-backlash elastic block 12 is rotatably connected to the housing 11, when the sliding block 10 rebounds from the bottom of the anti-backlash elastic block 12 and moves upward, when the anti-backlash elastic block 12 contacts the sliding block 10, the anti-backlash elastic block 12 swings to a certain extent under the push of the sliding block 10, and the anti-backlash elastic block 12 drives the rotating shaft 16 to rotate, the rotating shaft 16 drives the driving gear 14 to rotate, the driving gear 14 drives the driven gear 13 to rotate, and the driven gear 13 rotates to store force in the torsion spring 15. Since the anti-backlash elastic block 12 swings from bottom to top, it can avoid the anti-backlash elastic block 12 from hard collision with the sliding block 10, has a certain buffering effect on the upward movement of the sliding block 10, reduces the frontal impact on the sliding block 10 and the anti-backlash elastic block 12, and is conducive to improving the service life of the sliding block 10 and the anti-backlash elastic block 12.

[0044] After the sliding block 10 stops moving upwards under the blocking action of the anti-backlash elastic block 12, the gas in the driving cylinder is also discharged, and the sliding block 10 moves downward under the action of its own gravity. The sliding block 10 moves downward away from the anti-backlash elastic block 12, and the driven gear 13 rotates in the opposite direction under the action of the torsion spring 15. The driven gear 13 drives the driving gear 14 to rotate in the opposite direction, and the driving gear 14 drives the anti-backlash elastic block 12 to swing through the rotating shaft 16 and reset to the initial tilted downward state.

[0045] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A test method for evaluating the anti-collision capability of a battery pack bottom, characterized in that: The following steps are involved: A. Battery pack pretreatment: measure the voltage and insulation resistance of the battery pack. The insulation resistance value should be ≥100Ω / V. Adjust the SOC state of the battery through the charging equipment. B. Test sample preparation: Fix the battery pack after adjusting the SOC on the lifting platform, determine the location of the weak point of the battery pack bottom collision according to the bottom structure of the battery pack and mark it on the bottom of the battery pack. If there is no obvious weak point, randomly select the collision point; C. Preparation of collision equipment: Select a punch that meets the requirements, connect the punch to the collision equipment, and perform functional debugging; D. Bottom collision test: adjust the punch position on the collision equipment so that the punch corresponds vertically to the marked position on the bottom of the battery pack. Set the collision energy according to the test conditions. The collision energy can be continuously adjusted between 20-500J. After starting the test, the cylinder drives the punch to move upward, and the punch collides with the bottom of the battery pack. After the collision, the sliding block moves downward to the bottom of the anti-recoil elastic block. E. Stand still for observation: After the collision, the battery pack should be left still for more than 120 minutes to observe whether there is any smoke or fire. F. Safety check after the test: Measure the voltage and insulation resistance of the battery pack. When the insulation resistance value is ≥100Ω / V, perform a sealing performance test. If the airtightness requirements are met, the test passes. The collision device comprises a housing and a driving cylinder for driving the punch to impact, the driving cylinder is connected to an air source; a vertical sliding rod is fixedly connected to the housing, a sliding block is vertically slidably connected to the sliding rod, the punch is detachably connected to the sliding block, and the sliding block is connected to the cylinder rod of the driving cylinder; An anti-rebound elastic stopper is rotatably connected to the housing, the free end of the anti-rebound elastic stopper is tilted downward, the anti-rebound elastic stopper is elastic, and the free end of the anti-rebound elastic stopper can abut against the sliding block; A buffer is installed on the shell, and the buffer includes a shell, a rotating shaft, a driving gear and a driven gear. The driving gear is coaxially fixedly connected to the rotating shaft, the driven gear is meshed with the driving gear, the driven gear and the rotating shaft are both rotatably connected in the shell, and a torsion spring is connected between the driven gear and the shell; the rotating shaft is fixedly connected to an anti-recoil elastic block.

2. A battery pack bottom anti-collision capability evaluation test method according to claim 1, characterized in that: In step A, the state of charge of the battery pack is adjusted within the range of 0%-100%.

3. A battery pack bottom anti-collision capability evaluation test method according to claim 1, characterized in that: In step B, it is necessary to determine whether the battery pack is equipped with a liquid cooling system. If so, the battery pack is filled with coolant and sealed.

4. A battery pack bottom anti-collision capability evaluation test method according to claim 1, characterized in that: The punch can be in the shape of a hemisphere, a mushroom head or a square; the punch is made of steel, copper or concrete.

5. A battery pack bottom anti-collision capability evaluation test method according to claim 1, characterized in that: In step D, the test information includes: collision energy, collision time, collision deformation and collision force.

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