Battery coolant leakage test system and test method

Abstract

The present application relates to a battery coolant leakage test system and test method, which relates to the field of electric vehicle battery testing technology. The system includes a liquid filling tank, an electronic scale, a liquid filling pipe, a liquid pump, a controller, and a closed cover. The battery pack is placed in the cover. 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. 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 cover. The cover is equipped with an exhaust valve. The outlet end of the exhaust valve is connected to an inflation pipe. The other end of the inflation pipe is connected to a cylinder body. The cylinder body is open at the end away from the inflation pipe. A piston is slidably arranged in the cylinder body. The present application adds coolant to the battery pack in a quantitative and constant speed, which has higher accuracy and facilitates finding the critical state of battery pack failure or even loss of control, avoiding repeated testing and reducing time and labor costs.

Description

Technical Field

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

[0002] Batteries, as the component with the highest safety risk in electric vehicles, require not only extensive structural and circuit design improvements but also a wide range of tests to assess their safety performance in various scenarios. Electric vehicle batteries heat up significantly during prolonged, high-power charging and discharging cycles, so some electric vehicles are equipped with a liquid cooling system to dissipate heat. Coolant leak testing requires identifying the boundary conditions for safety failures such as battery insulation failure and thermal runaway.

[0003] An existing invention patent application with publication number CN110244232A discloses a method for testing the reliability of coolant leakage in a power battery liquid cooling system. The method includes the following steps: modifying the power battery liquid cooling system; setting up a test platform: securing the power battery system to the table of a rollover tester, connecting the power battery system's low-voltage wiring harness to the CAN communication information acquisition system, debugging the power battery system's communication information acquisition system on a console, and monitoring the power battery system's single cell temperature and single cell voltage in real time; and post-test inspection: testing the power battery system's insulation resistance, checking the power battery system's communication status, and unpacking and inspecting key components of the power battery system. Before testing, adjust the flow rate of the constant-current pump and inject 5L of coolant into the power battery system through the liquid cooling plate inlet.

[0004] Regarding the above-mentioned related technologies, conventional coolant leakage is just a one-time addition of a fixed amount of coolant, which can only determine the safety status of the current amount. If boundary conditions need to be found, repeated testing is required, which is time-consuming, labor-intensive and costly. Summary of the Invention

[0005] The present application provides a battery coolant leakage testing system and testing method, which can add coolant into the battery pack at a quantitative and constant speed, with higher accuracy, making it easier to find the critical state of battery failure or even loss of control, avoiding repeated testing and reducing time and labor costs.

[0006] This application provides a battery coolant leakage test system, which adopts the following technical solutions:

[0007] A battery coolant leakage test system includes a liquid filling tank, an electronic scale, a liquid filling pipe, a liquid pump, a controller, and a closed cover. The battery pack is placed in the cover, 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 cover, the cover is equipped with an exhaust valve, the air outlet end of the exhaust valve is connected to the inflation pipe, the other end of the inflation pipe is connected to a cylinder body, the cylinder body is open at the end away from the inflation pipe, and a piston is slidably arranged in the cylinder body.

[0008] By adopting this technical solution, the battery pack is continuously charged or discharged. A controller controls the operation of the liquid pump, adding coolant to the battery pack at a constant rate and quantity. The coolant flow rate is recorded, and the total weight of the liquid tank and the coolant inside is measured and recorded using an electronic scale. As the air inside the housing expands, it enters the cylinder through the inflation tube, pushing the piston. The piston's position is used to determine the amount of expansion or increase in the gas inside the housing.

[0009] Optionally, the cylinder body and the liquid adding tank are both made of transparent materials, the cylinder body is located next to the liquid adding tank, and the internal cross-sectional dimensions of the cylinder body and the liquid adding tank are the same.

[0010] By adopting this technical solution, the height of the piston can be easily observed through the transparent cylinder, and the height of the liquid level in the liquid tank can be easily observed through the transparent liquid tank. When the air expansion in the housing is small, the volume of coolant input into the battery pack is roughly equal to the volume of gas discharged from the housing. As the liquid level in the liquid tank drops, the height of the piston also drops, and the drop distance is basically the same, providing personnel with a reference for the safe and stable state of the battery pack.

[0011] Optionally, the cylinder body is arranged vertically, and the open end of the cylinder body is located at the bottom end of the cylinder body.

[0012] By adopting the above technical solution, most of the resistance to the downward movement of the piston is offset by the gravity of the piston, so that the piston moves downward smoothly.

[0013] 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.

[0014] By adopting the above technical solution, the sliding state of the piston is stabilized by the guide rod, thereby preventing the piston from tilting and getting stuck.

[0015] Optionally, a liquid flow meter is installed on the liquid adding pipe, a smoke alarm is installed in the cover shell, and a pressure gauge is installed in the cover shell, and a detection end of the pressure gauge is located in the cover shell.

[0016] By adopting the above technical solution, the flow of coolant input into the battery pack is monitored by a liquid flow meter and recorded, and the air pressure inside the cover is monitored by a pressure gauge.

[0017] Optionally, a one-way valve is installed on the liquid adding pipe, and the one-way conducting direction of the one-way valve is the direction from the liquid adding tank to the liquid pump.

[0018] By adopting the above technical solution, the backflow of the coolant is avoided through the one-way valve.

[0019] Optionally, the liquid adding tank is provided with a connecting rod that slides in the vertical direction, one end of the connecting rod is located in the liquid adding tank and is fixed with a float, and the other end of the connecting rod is fixed with an alarm switch, which is located below the piston and is used for the piston to press.

[0020] With this technical solution, the float floats on the surface of the coolant in the tank, and the connecting rod's height rises and falls with the liquid level in the tank. As the liquid level drops, the alarm switch also lowers, increasing the distance the piston needs to move downward to press the alarm switch, raising the alarm threshold for piston downward movement. When a significant amount of gas accumulates in the cylinder, the piston moves downward, pressing the alarm switch to alert personnel.

[0021] Optionally, the coolant outlet of the battery pack is installed with a volume flow meter 1, and the inflation pipe is installed with a volume flow meter 2.

[0022] By adopting the above technical solution, the values ​​of volume flow meter 1 and volume flow meter 2 are used to observe and record the gas outflow in the battery pack and the cover, so as to judge the sealing performance of the outer wall of the battery pack.

[0023] In a second aspect, the present application provides a battery coolant leakage testing method, which adopts the following technical solution:

[0024] The battery coolant leakage test method, using the battery coolant leakage test system described above, includes the following steps:

[0025] Step S1: The battery pack is in a continuous charging or discharging state. The controller controls the operation of the liquid pump to add coolant to the battery pack at a constant rate and a fixed quantity. The coolant flow rate is recorded. At the same time, the total weight of the liquid filling tank and the coolant inside is weighed and recorded using an electronic scale. The air pressure value in the housing and the insulation value of the battery pack are also recorded.

[0026] Step S2: As the test time continues, the recorded parameters form a corresponding relationship along the time axis;

[0027] Step S3: Observe the external state of the battery pack and, in conjunction with the smoke alarm, stop the test when the battery pack is in a dangerous state;

[0028] Step S4: Find the boundary conditions of the battery pack safety failure phenomenon based on the records.

[0029] By employing this technical solution, the recorded parameters form a timeline relationship as the test progresses. By adding coolant to the battery pack at a constant rate and in a fixed quantity, greater accuracy is achieved, making it easier to identify critical states where the battery pack could fail or even lose control, avoiding repeated testing and reducing time and labor costs.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] 1. By adding coolant to the battery pack at a constant rate and in a fixed quantity, the accuracy is higher, making it easier to find the critical state of battery pack failure or even loss of control, avoiding repeated testing and reducing time and labor costs;

[0032] 2. The cylinder and piston make it easy to observe the volume increase inside the housing and compare it, thus providing a reference for whether the battery pack is operating safely;

[0033] 3. Volume flow meter 1 and volume flow meter 2 can be used to observe and record the gas outflow from the battery pack and the cover, thereby judging the sealing performance of the outer wall of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a system diagram of a battery coolant leakage testing system according to an embodiment;

[0035] Figure 2 yes Figure 1 A partial enlarged view of .

[0036] Explanation of the accompanying symbols: 1. Liquid filling tank; 11. Electronic scale; 2. Liquid filling pipe; 21. Liquid pump; 3. Cover; 4. Battery pack; 22. One-way valve; 23. Liquid flow meter; 31. Smoke alarm; 32. Pressure gauge; 33. Exhaust valve; 5. Inflation tube; 6. Cylinder; 61. Piston; 34. Vent valve; 62. Guide rod; 7. Connecting rod; 71. Float; 72. Alarm switch; 41. Volume flow meter one; 51. Volume flow meter two. DETAILED DESCRIPTION

[0037] The present application is further described in detail below with reference to the accompanying drawings.

[0038] Example 1

[0039] Reference Figure 1 and Figure 2This embodiment discloses a battery coolant leakage test system, comprising a liquid filling tank 1, an electronic scale 11, a liquid filling tube 2, a liquid pump 21, a controller, and a sealed housing 3. A battery pack 4 is placed within the housing 3. The housing 3 is preferably made of a transparent material for easy observation. The housing 3 is equipped with a door for opening and closing, or a lid for opening and closing. When the housing 3 is closed, it is sealed with a sealing strip.

[0040] The coolant line inside battery pack 4 is damaged. Liquid pump 21 is electrically connected to the controller. Liquid filling tank 1 is placed on an electronic scale 11. One end of liquid filling tube 2 is connected to liquid filling tank 1, and the other end of liquid filling tube 2 is connected to the coolant inlet of battery pack 4 via liquid pump 21. The coolant outlet of battery pack 4 is connected to the interior of housing 3. In the coolant leakage test of this application, the coolant is not circulated. Instead, the coolant entering battery pack 4 seeps through the damaged area into the battery cells or into the circuitry, thereby simulating a coolant leak inside battery pack 4.

[0041] A one-way valve 22 is installed on the liquid filling pipe 2. The one-way valve 22 conducts from the liquid filling tank 1 toward the liquid pump 21, preventing coolant backflow. A liquid flow meter 23 is installed on the liquid filling pipe 2 to monitor and record the coolant flow entering the battery pack 4.

[0042] A smoke alarm 31 is mounted within the housing 3. A barometer 32 is also mounted within the housing 3. The detection end of the barometer 32 is located within the housing 3. If the battery pack 4 enters a dangerous state and produces smoke, the smoke alarm 31 will sound an alarm when the smoke concentration reaches a set value. The barometer 32 monitors the air pressure within the housing 3.

[0043] The housing 3 is mounted with an exhaust valve 33, the outlet end of which is connected to an air charging tube 5. The other end of the air charging tube 5 is connected to a cylinder 6. The end of the cylinder 6, which is away from the air charging tube 5, is open, and a piston 61 is slidably mounted within the cylinder 6. The piston 61 forms a sliding seal with the inner wall of the cylinder 6 via its rubber outer wall. The cylinder 6 is vertically mounted, with its open end at the bottom. The weight of the piston 61 offsets most of the resistance to its downward movement. When air accumulates in the upper portion of the cylinder 6, the air pressure drives the piston 61 downward.

[0044] It should be noted that as the air in housing 3 expands or increases, it enters cylinder 6 through exhaust valve 33 and inflation tube 5. However, the air remains confined within the enclosed space, and the air in housing 3 is not connected to the outside atmosphere. Exhaust valve 33 is a one-way structure, and after passing through exhaust valve 33, the air in housing 3 cannot enter housing 3 in the opposite direction.

[0045] The cylinder body 6 and the liquid adding tank 1 are both made of transparent materials. The cylinder body 6 is located next to the liquid adding tank 1, and the internal cross-sectional dimensions of the cylinder body 6 and the liquid adding tank 1 are the same. The transparent cylinder body 6 makes it easy to observe the height position of the piston 61, and the transparent liquid adding tank 1 makes it easy to observe the height position of the liquid level in the liquid adding tank 1. The cylinder body 6 and the liquid adding tank 1 are both cylindrical, with the same inner diameter. With this arrangement, when the amount of air expansion in the cover 3 is small, the volume of coolant input into the battery pack 4 is essentially equal to the volume of gas discharged from the cover 3. That is, as the liquid level in the liquid adding tank 1 drops, the height position of the piston 61 also drops, and the drop distance is essentially the same, providing staff with a reference for whether the battery pack 4 is in a safe and stable state.

[0046] The housing 3 is also connected to a solenoid-operated vent valve 34, whose outer end is connected to the atmosphere. At the start of the test, when the temperature of the battery pack 4 rises, the operator can open the vent valve 34 to allow the expanded air within the housing 3 to escape through the valve. The valve can then be closed to reduce the effect of the heat from the normal operation of the battery pack 4 on the expansion of the air and minimize errors in the movement of the piston 61.

[0047] Cylinder body 6 is relatively fixed with a guide rod 62. Specifically, cylinder body 6 and guide rod 62 are respectively fixed to the frame. Guide rod 62 passes through piston 61 and is slidably connected to piston 61. Guide rod 62 penetrates cylinder body 6 from the bottom. Piston 61 forms a sliding seal with the outer wall of guide rod 62 through the inner wall of the rubber material. Guide rod 62 stabilizes the sliding state of piston 61 and prevents piston 61 from tilting and getting stuck.

[0048] The liquid adding tank 1 is provided with a connecting rod 7 that slides in the vertical direction and is also slidably connected to the frame. The connecting rod 7 is bent into an S-shape. One end of the connecting rod 7 is located in the liquid adding tank 1 and is fixed with a float 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 to be pressed by the piston 61. The float 71 floats on the surface of the coolant in the liquid adding tank 1. The height of the connecting rod 7 rises and falls with the height of the liquid in the liquid adding tank 1. When the liquid level drops, the height of the alarm switch 72 also drops. The distance required for the piston 61 to move downward to press the alarm switch 72 increases, thereby increasing the alarm threshold for the downward movement of the piston 61 and avoiding false alarms caused by excessive coolant input.

[0049] The coolant outlet of battery pack 4 is equipped with volume flow meter 1 41 , and the gas charging tube 5 is equipped with volume flow meter 2 51 . Both volume flow meter 1 41 and volume flow meter 2 51 are electronic, capable of displaying and recording the flow rate and volume of gas passing through. Gas from battery pack 4 that passes through volume flow meter 1 41 enters housing 3 .

[0050] If battery pack 4 is operating properly, the volume of coolant entering the pack should be roughly equal to the flow-through volume recorded by volume flowmeter 1 41. If there is a significant difference between the values, the data can be used to assess the expansion of the gas in the cooling circuit within the pack 4. If the outer wall of the pack 4 is well sealed and the outer wall temperature remains stable, the flow-through volume displayed by volume flowmeter 1 41 should be roughly equal to the flow-through volume displayed by volume flowmeter 2 51. If there is a significant difference between the values, the data can be used to assess the expansion of the air outside the pack 4 and the sealing integrity of the outer wall of the pack 4. If the value displayed by volume flowmeter 1 41 is close to zero and the value displayed by volume flowmeter 2 51 is large, this indicates that most of the air within the pack 4 has leaked out through the outer wall of the pack 4, and the sealing integrity of the inside and outside of the pack 4 has been significantly impaired.

[0051] Example 2

[0052] A battery coolant leakage testing method, using the battery coolant leakage testing system of embodiment 1, includes the following steps:

[0053] Step S1: The battery pack 4 is in a continuous charging or discharging state, and the test voltage is a low voltage, such as 13.5V. The controller controls the operation of the liquid pump 21 to add coolant to the battery pack 4 at a constant rate and a fixed quantity. The coolant flow rate is recorded. Simultaneously, the electronic scale 11 is used to weigh the total weight of the liquid tank 1 and the coolant therein. The air pressure within the housing 3 and the insulation value of the battery pack 4 are also recorded.

[0054] It should be noted that within 5-10 minutes of starting the test, the vent valve 34 is opened to allow the battery pack 4 temperature to rise normally, and the expanded air in the housing 3 is discharged from the housing 3. The vent valve 34 is then closed. The initial height position of the piston 61 is close to the height position of the liquid level in the liquid tank 1.

[0055] Step S2: As the test time continues, the recorded parameters form a corresponding relationship along the time axis, and the weight reduction measured by the electronic scale 11 is the weight of the coolant input into the battery pack 4.

[0056] The entire test period can last several days.

[0057] Step S3: Observe the external state of the battery pack 4 and simultaneously activate the smoke alarm 31 . Stop the test when the battery pack 4 is in a dangerous state.

[0058] The operator can observe the position of piston 61 and the liquid level in the liquid tank 1. When piston 61 and the liquid level are close, the air in the housing 3 has not expanded much and the temperature of the battery pack 4 is safe. If the position of piston 61 and the liquid level further expand until piston 61 presses the alarm switch 72, it indicates that the air in the housing 3 has expanded significantly due to excessive temperature, or that a large amount of gas has been generated by a chemical reaction inside the battery pack 4, resulting in a dangerous state. At this time, the test is stopped and the vent valve 34 is opened to vent air.

[0059] Step S4: Find the boundary conditions of the safety failure phenomenon of the battery pack 4 according to the records. The boundary conditions include the amount of coolant leakage inside the battery pack 4, the duration, etc.

[0060] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. Battery coolant leakage test system, characterized by: The invention comprises a liquid adding tank (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); a coolant pipeline inside the battery pack (4) is damaged, and the coolant input into the battery pack (4) penetrates between battery elements or onto the circuit through the damaged position, thereby simulating a scenario in which the coolant inside the battery pack (4) leaks; The liquid pump (21) is electrically connected to the controller, the liquid adding tank (1) is placed on the electronic scale (11), one end of the liquid adding pipe (2) is connected to the liquid adding tank (1), the other end of the liquid adding 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 cover (3), the cover (3) is equipped with an exhaust valve (33), the outlet end of the exhaust valve (33) is connected to the inflation pipe (5), the other end of the inflation pipe (5) is connected to the cylinder (6), the cylinder (6) is open at the end away from the inflation pipe (5), and a piston (61) is slidably arranged in the cylinder (6); The coolant outlet of the battery pack (4) is equipped with a volume flow meter 1 (41), and the inflation tube (5) is equipped with a volume flow meter 2 (51). The volume flow meter 1 (41) and the volume flow meter 2 (51) are capable of displaying and recording the flow rate and the volume of the gas passing through. By comparing the coolant volume input into the battery pack (4), the flow volume displayed by the volume flow meter 1 (41), and the flow volume displayed by the volume flow meter 2 (51), the sealing integrity of the outer wall of the battery pack (4) is tested.

2. The battery coolant leakage testing 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). The internal cross-sectional dimensions of the cylinder body (6) and the liquid adding box (1) are the same.

3. The battery coolant leakage testing 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 testing system according to claim 1, characterized in that: A guide rod (62) is fixed relatively 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 testing 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 pressure gauge (32) is installed in the housing (3), with a detection end of the pressure gauge (32) located in the housing (3).

6. The battery coolant leakage testing 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 testing system according to claim 1, characterized in that: The liquid adding tank (1) is provided with a connecting rod (7) which slides in a 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 the alarm switch (72).

8. A battery coolant leakage testing method, characterized in that: The battery coolant leakage test system according to any one of claims 1 to 7 is used, comprising the following steps: Step S1: The battery pack (4) is in a continuous charging or discharging state, and the controller controls the operation of the liquid pump (21) to add coolant to the battery pack (4) at a constant rate and quantity, and records the coolant flow rate. At the same time, the electronic scale (11) is used to weigh the total weight of the liquid tank (1) and the coolant therein, and records the air pressure value in the housing (3) and the insulation value of the battery pack (4); 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: Finding the boundary conditions of the safety failure phenomenon of the battery pack (4) based on the records.

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