Battery cooling liquid leakage test system and test method

Abstract

The invention relates to a battery cooling liquid leakage testing system and method, and relates to the technical field of electric vehicle battery testing, the battery cooling liquid leakage testing system comprises a liquid adding box, an electronic scale, a liquid adding pipe, a liquid pump, a controller and a closed housing, a battery pack is placed in the housing, a cooling liquid pipeline in the battery pack is damaged, and the liquid pump is electrically connected with the controller. The liquid adding box is placed on the electronic scale, one end of the liquid adding pipe is communicated with the liquid adding box, the other end of the liquid adding pipe is communicated with a cooling liquid inlet of the battery pack through a liquid pump, a cooling liquid outlet of the battery pack is communicated with the interior of the housing, the housing is provided with an exhaust valve, the air outlet end of the exhaust valve is connected with an inflation pipe, and the other end of the inflation pipe is communicated with a cylinder body. The end, away from the inflation pipe, of the cylinder body is open, and a piston is slidably arranged in the cylinder body. By quantitatively filling the cooling liquid into the battery pack at a constant speed, the precision is higher, the failure and even out-of-control critical state of the battery pack can be conveniently found, repeated testing is avoided, and the time and labor cost is reduced.

Description

Technical Field

[0001] This application relates to the technical field of tram battery testing, and in particular to a battery coolant leakage testing system and a testing method. Background Art

[0002] In a tram, the battery is the component with the highest safety risk. Not only does it require a large number of structural and circuit designs to increase safety, but also a variety of tests need to be carried out to evaluate the safety performance of the battery in various situations. The power battery of a tram will significantly increase in temperature under long-term and high-power charge and discharge. Therefore, some trams are equipped with a liquid cooling circulation system to dissipate heat from the battery. For the coolant leakage test, the test needs to find the boundary conditions of safety failure phenomena such as battery insulation failure and thermal runaway.

[0003] The existing invention patent application with the publication number CN110244232A discloses a method for testing the reliability of coolant leakage in a power battery liquid cooling system, including the following steps: transformation of the power battery liquid cooling system; construction of the test platform: fixing the power battery system to the tabletop of the flipping test machine, connecting the low-voltage wire harness of the power battery system to the CAN communication information acquisition system, debugging the communication information acquisition system of the power battery system on the console, and real-time monitoring of the temperature and voltage of the single cells of the power battery system; inspection after the test: testing the insulation resistance value of the power battery system, checking the communication status of the power battery system, and unpacking and inspecting the key components of the power battery system. Before the test, adjust the flow rate of the constant flow pump and inject 5L of coolant into the power battery system from the inlet of the liquid cooling plate.

[0004] Regarding the above related technologies, the conventional coolant leakage test only fills a fixed amount of coolant at one time, and can only determine the safety status of the current amount. If the boundary conditions need to be found, repeated tests are required, which is time-consuming, laborious and costly. Summary of the Invention

[0005] This application provides a battery coolant leakage testing system and a testing method, which can quantitatively and at a constant speed inject coolant into the battery pack with higher precision, facilitating the search for the critical state of battery failure or even out-of-control, avoiding repeated tests, and reducing time and labor costs.

[0006] A battery coolant leakage testing system provided by this application adopts the following technical solutions: Battery coolant leakage test system, including a liquid filling tank, an electronic scale, a liquid filling pipe, a liquid pump, a controller, and an enclosed housing. The battery pack is placed inside the housing, and the coolant pipeline inside the battery pack is damaged. The liquid pump is electrically connected to the controller. The liquid filling tank is placed on the electronic scale. One end of the liquid filling pipe is connected to the liquid filling tank, and the other end of the liquid filling pipe is connected to the coolant inlet of the battery pack through the liquid pump. The coolant outlet of the battery pack is connected to the inside of the housing. The housing is equipped with an exhaust valve, and the outlet end of the exhaust valve is connected to a charging pipe. The other end of the charging pipe is connected to a cylinder body, and the end of the cylinder body away from the charging pipe is open. A piston is slidably arranged inside the cylinder body.

[0007] By adopting the above technical solution, the battery pack is in a continuous charging or discharging state. The controller controls the operation of the liquid pump to quantitatively and at a constant speed fill the battery pack with coolant, record the coolant flow rate, and at the same time weigh the total weight of the liquid filling tank and the coolant inside it through the electronic scale for recording. When the air in the housing expands, the gas will enter the cylinder body through the charging pipe to push the piston to move, and the position of the piston is used to judge the gas expansion amount or increase amount in the housing.

[0008] Optionally, both the cylinder body and the liquid filling tank are made of transparent materials. The cylinder body is located beside the liquid filling tank, and the internal cross-sectional dimensions of the cylinder body and the liquid filling tank are the same.

[0009] By adopting the above technical solution, through the transparent cylinder body, it is convenient to observe the height position of the piston, and through the transparent liquid filling tank, it is convenient to observe the height position of the liquid level in the liquid filling tank. When the air expansion amount in the housing is small, the volume of coolant input into the battery pack is basically equal to the volume of gas discharged from the housing. As the liquid level in the liquid filling tank drops, the height position of the piston also drops, and the dropped distance is basically the same, providing a reference for the staff on the safe and stable state of the battery pack.

[0010] Optionally, the cylinder body is vertically arranged, and the open end of the cylinder body is located at the bottom end of the cylinder body.

[0011] By adopting the above technical solution, the gravity of the piston offsets most of the resistance for the piston to move downward, making the piston move smoothly downward.

[0012] Optionally, a guide rod is relatively fixed to the cylinder body, and the guide rod passes through the piston and is slidably connected to the piston.

[0013] By adopting the above technical solution, the piston slides stably through the guide rod, avoiding the piston from tilting and jamming.

[0014] Optionally, a liquid flowmeter is installed on the liquid filling pipe, a smoke alarm is installed inside the housing, and a pressure gauge is installed on the housing, and the detection end of the pressure gauge is located inside the housing.

[0015] By adopting the above technical solution, the coolant flow rate input into the battery pack is monitored by a liquid flow meter for recording, and the air pressure inside the housing is monitored by a barometer.

[0016] Optionally, a one-way valve is installed on the liquid filling pipe, and the one-way conduction direction of the one-way valve is from the liquid filling tank towards the liquid pump.

[0017] By adopting the above technical solution, the one-way valve is used to prevent the coolant from flowing back.

[0018] Optionally, a connecting rod is slidably arranged vertically on the liquid filling tank. One end of the connecting rod is located inside the liquid filling tank and is fixed with a floating block, and the other end of the connecting rod is fixed with an alarm switch. The alarm switch is located below the piston and is used to be pressed by the piston.

[0019] By adopting the above technical solution, the floating block floats on the surface of the coolant inside the liquid filling tank. The height position of the connecting rod rises and falls with the height of the liquid level inside the liquid filling tank. After the liquid level drops, the height position of the alarm switch also decreases, and the distance required for the piston to move downward and press the alarm switch increases, thereby increasing the alarm threshold for the piston to move downward. When a large amount of gas accumulates in the cylinder body, the piston moves downward to press the alarm switch to warn the staff.

[0020] Optionally, a volumetric flow meter I is installed at the coolant outlet of the battery pack, and a volumetric flow meter II is installed on the charging pipe.

[0021] By adopting the above technical solution, the amount of gas vented from inside the battery pack and inside the housing is observed and recorded based on the values of the volumetric flow meter I and the volumetric flow meter II, thereby evaluating the sealing performance of the outer wall of the battery pack.

[0022] In a second aspect, the present application provides a method for testing battery coolant leakage, adopting the following technical solution: The method for testing battery coolant leakage uses the above battery coolant leakage test system, and includes the following steps: Step S1: The battery pack is in a continuous charging or discharging state. The liquid pump is controlled by a controller to operate, and coolant is quantitatively and constantly added to the inside of the battery pack. The coolant flow rate is recorded. At the same time, the total weight of the liquid filling tank and the coolant inside it is weighed by an electronic scale for recording. At the same time, the air pressure value inside the housing and the insulation value of the battery pack are recorded; Step S2: As the test time continues, the recorded parameters form a corresponding relationship along the time axis; Step S3: Observe the external state of the battery pack, and at the same time in combination with a smoke alarm, stop the test when the battery pack is in a dangerous state; Step S4: According to the records, find the boundary conditions for the safety failure phenomenon of the battery pack.

[0023] By adopting the above technical solution, as the test time continues, the recorded parameters form a corresponding relationship along the time axis. By quantitatively and steadily injecting the coolant into the battery pack, the accuracy is higher, which is convenient for finding the critical state of battery pack failure or even out-of-control, avoiding repeated tests, and reducing time and labor costs.

[0024] In summary, the present application includes at least one of the following beneficial technical effects: 1. By quantitatively and steadily injecting the coolant into the battery pack, the accuracy is higher, which is convenient for finding the critical state of battery pack failure or even out-of-control, avoiding repeated tests, and reducing time and labor costs; 2. Through the cylinder block and the piston, it is convenient to observe the volume increase in the housing and make a comparison, thereby providing a reference for whether the battery pack operates safely; 3. Through the first volume flowmeter and the second volume flowmeter, the gas outflow amounts in the battery pack and the housing can be observed and recorded, thereby evaluating the outer wall sealing performance of the battery pack. Description of the Drawings

[0025] Figure 1 is a system diagram of a battery coolant leakage test system according to an embodiment; Figure 2 is Figure 1 a partial enlarged view of

[0026] Description of the reference numerals: 1. Liquid filling tank; 11. Electronic scale; 2. Liquid filling pipe; 21. Liquid pump; 3. Housing; 4. Battery pack; 22. Check valve; 23. Liquid flowmeter; 31. Smoke alarm; 32. Pressure gauge; 33. Exhaust valve; 5. Inflation pipe; 6. Cylinder block; 61. Piston; 34. Vent valve; 62. Guide rod; 7. Connecting rod; 71. Floating block; 72. Alarm switch; 41. First volume flowmeter; 51. Second volume flowmeter. Detailed Embodiments

[0027] The following further describes the present application in detail with reference to the drawings.

[0028] Embodiment 1

[0029] Referring to Figure 1 and Figure 2 , this embodiment discloses a battery coolant leakage test system, including a liquid filling tank 1, an electronic scale 11, a liquid filling pipe 2, a liquid pump 21, a controller, and a housing 3 that is enclosed. The battery pack 4 is placed inside the housing 3. The housing 3 is preferably made of a transparent material for easy observation. The housing 3 is provided with a door or a lid for opening and closing. After the housing 3 is closed, it is sealed through a sealing strip.

[0030] The coolant pipeline inside the battery pack 4 is damaged. The liquid pump 21 is electrically connected to the controller. The liquid filling tank 1 is placed on the electronic scale 11. One end of the liquid filling pipe 2 is connected to the liquid filling tank 1, and the other end of the liquid filling pipe 2 is connected to the coolant inlet of the battery pack 4 through the liquid pump 21. The coolant outlet of the battery pack 4 is connected to the inside of the housing 3. In the coolant leakage test of this application, the coolant does not circulate, and the coolant input into the battery pack 4 seeps between the battery components or onto the circuit through the damaged position, thereby simulating the scenario of coolant leakage inside the battery pack 4.

[0031] A one-way valve 22 is installed on the liquid filling pipe 2. The one-way conduction direction of the one-way valve 22 is from the liquid filling tank 1 towards the liquid pump 21, and the one-way valve 22 prevents the coolant from flowing back. A liquid flowmeter 23 is installed on the liquid filling pipe 2. The liquid flowmeter 23 monitors the coolant flow rate input into the battery pack 4 and records it at the same time.

[0032] A smoke alarm 31 is installed inside the housing 3. The housing 3 is equipped with a pressure gauge 32, and the detection end of the pressure gauge 32 is located inside the housing 3. If the battery pack 4 enters a dangerous state and generates smoke, when the smoke concentration reaches the set value, the smoke alarm 31 issues an alarm; the pressure inside the housing 3 is monitored through the pressure gauge 32.

[0033] An exhaust valve 33 is installed on the housing 3. The outlet end of the exhaust valve 33 is connected to an inflation pipe 5. The other end of the inflation pipe 5 is connected to a cylinder block 6. The end of the cylinder block 6 away from the inflation pipe 5 is open. A piston 61 is slidably arranged inside the cylinder block 6. The piston 61 establishes a sliding seal with the inner wall of the cylinder block 6 through its rubber outer wall. The cylinder block 6 is vertically arranged, and the open end of the cylinder block 6 is located at the bottom end of the cylinder block 6. The gravity of the piston 61 offsets most of the resistance to the downward movement of the piston 61. When the air in the upper part of the cylinder block 6 increases, the air pressure drives the piston 61 to move downward.

[0034] It should be noted that as the air in the housing 3 expands or increases, the air enters the inside of the cylinder block 6 through the exhaust valve 33 and the inflation pipe 5, and the gas is still restricted within the closed space. The gas inside the housing 3 is not connected to the outside atmosphere. The exhaust valve 33 is a one-way structure. After the air inside the housing 3 passes through the exhaust valve 33, it will not reverse and enter the housing 3.

[0035] The cylinder block 6 and the liquid filling tank 1 are both made of transparent materials. The cylinder block 6 is located beside the liquid filling tank 1, and the internal cross-sectional dimensions of the cylinder block 6 and the liquid filling tank 1 are the same. Through the transparent cylinder block 6, it is convenient to observe the height position of the piston 61. Through the transparent liquid filling tank 1, it is convenient to observe the height position of the liquid level in the liquid filling tank 1. The cylinder block 6 and the liquid filling tank 1 are both cylindrical, and their inner diameters are the same. With such a setting, when the air expansion amount in the housing 3 is small, the volume of the coolant input into the battery pack 4 is basically equal to the volume of the gas discharged from the housing 3. That is, as the liquid level in the liquid filling tank 1 drops, the height position of the piston 61 also drops, and the dropping distances are basically the same, providing a reference for the staff on the safe and stable state of the battery pack 4.

[0036] The housing 3 is also connected and installed with a ventilation valve 34. The outer end of the ventilation valve 34 is connected to the atmosphere, and the ventilation valve 34 is an electromagnetic valve. At the start of the test, when the temperature of the battery pack 4 rises, the staff can open the ventilation valve 34 to discharge the expanded air in the housing 3 through the ventilation valve 34, and then close the ventilation valve 34 to reduce the influence of the heat generated by the normal operation of the battery pack 4 on air expansion and reduce the error of the piston 61 movement.

[0037] The cylinder block 6 is relatively fixed with a guide rod 62. Specifically, the cylinder block 6 and the guide rod 62 are respectively fixed to the frame. The guide rod 62 passes through the piston 61 and is slidably connected to the piston 61. The guide rod 62 penetrates into the cylinder block 6 from below the cylinder block 6. The piston 61 establishes a sliding seal with the outer wall of the guide rod 62 through the inner hole wall made of rubber material. Through the guide rod 62, the sliding state of the piston 61 is stable, avoiding the piston 61 from tilting and jamming.

[0038] The liquid filling tank 1 is slidably provided with a connecting rod 7 in the vertical direction, and the connecting rod 7 is also slidably connected to the frame. The connecting rod 7 is bent in an S shape. One end of the connecting rod 7 is located in the liquid filling tank 1 and is fixed with a floating block 71, and the other end of the connecting rod 7 is fixed with an alarm switch 72. The alarm switch 72 is located below the piston 61 and is used for the piston 61 to press. The floating block 71 floats on the surface of the coolant in the liquid filling tank 1. The height position of the connecting rod 7 rises and falls with the height of the liquid level in the liquid filling tank 1. After the liquid level drops, the height position of the alarm switch 72 also decreases, and the distance required for the piston 61 to move downward and press the alarm switch 72 increases, increasing the alarm threshold for the piston 61 to move downward and avoiding false alarms caused by excessive input of coolant.

[0039] A volume flowmeter one 41 is installed at the coolant outlet of the battery pack 4, and a volume flowmeter two 51 is installed on the charging pipe 5. Both the volume flowmeter one 41 and the volume flowmeter two 51 are in electronic form and can display and record the flow rate and the volume of the passing gas. The gas passing through the volume flowmeter one 41 in the battery pack 4 enters the housing 3.

[0040] If the battery pack 4 is working properly, the volume of the coolant input into the battery pack 4 should be basically equal to the volume flowing through recorded by the volume flowmeter 1 - 41. If the values differ significantly, the gas expansion volume in the cooling pipeline inside the battery pack 4 can be judged through the data. If the outer wall of the battery pack 4 has good sealing and the outer wall temperature remains stable, the volume flowing through shown by the volume flowmeter 1 - 41 should be basically equal to the volume flowing through shown by the volume flowmeter 2 - 51. If the values differ significantly, the expansion volume of the external air of the battery pack 4 and the sealing integrity of the outer wall of the battery pack 4 can be judged through the data. If the value shown by the volume flowmeter 1 - 41 is close to zero and the value shown by the volume flowmeter 2 - 51 is large, it means that most of the air inside the battery pack 4 leaks out through the outer wall of the battery pack 4, and there are significant defects in the sealing integrity inside and outside the battery pack 4.

[0041] Embodiment 2

[0042] A method for testing battery coolant leakage, using the battery coolant leakage test system of Embodiment 1, includes the following steps: Step S1: The battery pack 4 is in a continuous charging or discharging state, and the test voltage is a small voltage, such as 13.5V. The liquid pump 21 is controlled by the controller to run, and the coolant is filled into the battery pack 4 quantitatively and at a constant speed. The coolant flow rate is recorded. At the same time, the total weight of the liquid filling tank 1 and the coolant inside it is weighed by the electronic scale 11 and recorded. At the same time, the air pressure value inside the housing 3 and the insulation value of the battery pack 4 are recorded.

[0043] It should be noted that within 5 - 10 minutes after the start of the test, the vent valve 34 is opened to allow the expanded air inside the housing 3 to be discharged from the housing 3 after the temperature of the battery pack 4 rises normally, and then the vent valve 34 is closed. The initial height position of the piston 61 is close to the height position of the liquid level inside the liquid filling tank 1.

[0044] Step S2: As the test time continues, the recorded parameters form a corresponding relationship along the time axis. The weight reduction measured by the electronic scale 11 is the weight of the coolant input into the battery pack 4.

[0045] The entire test time can last for several days.

[0046] Step S3: Observe the external state of the battery pack 4, and at the same time, in combination with the smoke alarm 31, stop the test when the battery pack 4 is in a dangerous state.

[0047] The operator can observe the height position of the piston 61 and the liquid level in the liquid filling tank 1. When the piston 61 is close to the liquid level, it indicates that the air expansion in the housing 3 is not large and the temperature of the battery pack 4 is in a safe state. When the height position of the piston 61 further expands relative to the liquid level until the piston 61 presses the alarm switch 72, it means that the air in the housing 3 expands significantly due to excessive temperature, or a large amount of gas is generated inside the battery pack 4 through chemical reactions, and it is in a dangerous state. At this time, the test is also stopped, and the vent valve 34 is opened to exhaust gas.

[0048] Step S4: Find the boundary conditions for the safe failure phenomenon of the battery pack 4 according to the records. These boundary conditions include the coolant leakage amount, duration, etc. inside the battery pack 4.

[0049] The above are all the preferred embodiments of the present application, and the protection scope of the present application is not limited thereby. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. Battery coolant leakage test system, characterized by: The invention comprises a liquid adding box (1), an electronic scale (11), a liquid adding pipe (2), a liquid pump (21), a controller, and a closed cover (3). A battery pack (4) is placed in the cover (3). The cooling liquid pipeline inside the battery pack (4) is damaged. The liquid pump (21) is electrically connected to the controller. The liquid adding box (1) is placed on the electronic scale (11). One end of the liquid adding pipe (2) is connected to the liquid adding box (1). The other end of the liquid adding pipe (2) is connected to the cooling liquid inlet of the battery pack (4) through the liquid pump (21). The cooling liquid outlet of the battery pack (4) is connected to the inside of the cover (3). The cover (3) is equipped with an exhaust valve (33). The exhaust end of the exhaust valve (33) is connected to an air charging pipe (5). The other end of the air charging pipe (5) is connected to a cylinder (6). The cylinder (6) is open at the end away from the air charging pipe (5). A piston (61) is slidably arranged in the cylinder (6).

2. The battery coolant leakage test system according to claim 1, characterized in that: The cylinder body (6) and the liquid adding box (1) are both made of transparent materials; the cylinder body (6) is located next to the liquid adding box (1); and the internal cross-sectional dimensions of the cylinder body (6) and the liquid adding box (1) are the same.

3. The battery coolant leakage test system according to claim 1, characterized in that: The cylinder body (6) is arranged vertically, and the open end of the cylinder body (6) is located at the bottom end of the cylinder body (6).

4. The battery coolant leakage test system according to claim 1, characterized in that: A guide rod (62) is relatively fixed to the cylinder body (6), and the guide rod (62) passes through the piston (61) and is slidably connected to the piston (61).

5. The battery coolant leakage test system according to claim 1, characterized in that: A liquid flow meter (23) is installed on the liquid adding pipe (2), a smoke alarm (31) is installed in the housing (3), and a barometer (32) is installed in the housing (3), wherein a detection end of the barometer (32) is located in the housing (3).

6. The battery coolant leakage test system according to claim 1, characterized in that: A one-way valve (22) is installed on the liquid adding pipe (2), and the one-way conducting direction of the one-way valve (22) is the direction from the liquid adding tank (1) toward the liquid pump (21).

7. The battery coolant leakage test system according to claim 1, characterized in that: The liquid adding tank (1) is provided with a connecting rod (7) which is slidable in the vertical direction. One end of the connecting rod (7) is located in the liquid adding tank (1) and is fixed with a floating block (71). The other end of the connecting rod (7) is fixed with an alarm switch (72). The alarm switch (72) is located below the piston (61) and is used for the piston (61) to press down.

8. The battery coolant leakage test system according to claim 1, characterized in that: The coolant outlet of the battery pack (4) is equipped with a volume flow meter 1 (41), and the inflation pipe (5) is equipped with a volume flow meter 2 (51).

9. A battery coolant leakage test method, characterized in that: The battery coolant leakage test system according to any one of claims 1 to 8 is used, comprising the following steps: Step S1: The battery pack (4) is in a continuous charging or discharging state. The controller controls the operation of the liquid pump (21) to add coolant into the battery pack (4) at a constant rate and in a quantitative manner. The coolant flow rate is recorded. At the same time, the total weight of the liquid adding tank (1) and the coolant therein is weighed and recorded by an electronic scale (11). At the same time, the air pressure value in the housing (3) and the insulation value of the battery pack (4) are recorded. Step S2: As the test time continues, the recorded parameters form a corresponding relationship along the time axis; Step S3: Observe the external state of the battery pack (4) and simultaneously activate the smoke alarm (31), and stop the test when the battery pack (4) is in a dangerous state; Step S4: Find the boundary conditions of the safety failure phenomenon of the battery pack (4) according to the records.

Images