Cylindrical lithium battery pack thermal runaway explosion suppression device

Abstract

The application relates to a cylindrical lithium battery pack thermal runaway explosion suppression device, which comprises a trigger mechanism, an electromagnetic valve and a gas storage tank, the gas storage tank is connected with a one-way valve of the trigger mechanism through a high-pressure gas pipe I, the one-way valve is communicated with a pressure relief cavity of a box body through a high-pressure gas pipe II; the electromagnetic valve is in a normally closed state and is connected with a thermal runaway alarm detection device in the battery pack; the thermal runaway alarm detection device judges that thermal runaway occurs in the battery pack and sends an alarm signal. The application comprehensively considers the release of flammable gas after battery runaway, the suppression of flammable gas explosion and the avoidance of greater destructive power caused by flammable gas deflagration, so that single cell runaway does not cause surrounding cell runaway.

Description

TECHNICAL FIELD

[0001] The present application relates to a power battery, in particular to a cylindrical lithium battery pack thermal runaway explosion suppression device. BACKGROUND

[0002] With the development of electric vehicles, the requirements for the endurance mileage and cycle life of lithium batteries of battery vehicles are gradually increasing. In order to improve the capacity and cycle life of single batteries, the nickel content of lithium batteries is gradually increased, but the thermal stability is getting worse, and the thermal runaway phenomenon is more likely to occur.

[0003] When the lithium battery loses control, a large amount of flammable gas is released, including carbon monoxide, hydrogen and small molecule combustible hydrocarbon substances, which together form a flammable mixed gas, and the temperature of the battery runaway gas exceeds 600℃, and the initial pressure exceeds 0.6Mpa. Under this condition, the explosion limit of the flammable mixed gas is 10% to 70%, so the flammable mixed gas released after the high-nickel system lithium battery loses control is extremely easy to explode, which in turn causes continuous explosion of the surrounding cells.

[0004] In order to solve the problem of lithium battery explosion after losing control, the battery pack needs to consider the explosion of flammable gas released after the battery loses control in the structural design, and the thermal runaway protection design is carried out to ensure that a single cell does not cause the surrounding cells to lose control after losing control, and to avoid causing greater damage.

[0005] The existing power battery system usually considers four aspects of early warning, heat dissipation, pressure relief and protection when designing safety. The heat dissipation mechanism adopts natural cooling, liquid cooling circulation and other ways, the pressure relief mechanism adopts explosion-proof valve opening and other ways, and the protection mechanism adopts flame-retardant material heat insulation and other ways. However, when the lithium battery loses control, a large amount of high-temperature and high-pressure flammable gas will be produced, which will produce deflagration when meeting air, and the deflagration time lasts less than 0.8s, the instantaneous maximum temperature of deflagration gas exceeds 1200℃, and the instantaneous maximum pressure exceeds 1bar. Therefore, the deflagration of flammable gas will cause greater damage to the power battery system. The heat dissipation and pressure relief mechanisms in the battery system have not been reacted, and the deflagration process has already ended. These protection mechanisms can only protect the power battery system after deflagration. SUMMARY

[0006] To solve the above problems, the present application provides a cylindrical lithium battery pack thermal runaway explosion suppression device, which releases flammable gas to suppress the explosion of flammable gas and effectively avoids greater damage caused by deflagration of flammable gas, thereby realizing that a single cell does not cause the surrounding cells to lose control after losing control.

[0007] The technical scheme adopted by the present application is: a cylindrical lithium battery pack thermal runaway explosion suppression device, characterized in that: comprising a trigger mechanism, an electromagnetic valve and a gas storage tank, the gas storage tank is connected with a one-way valve of the trigger mechanism through a high-pressure gas pipe I, the one-way valve is communicated with a pressure relief cavity of a box through a high-pressure gas pipe II; the electromagnetic valve is in a normally closed state and is connected with a thermal runaway alarm detection device in the battery pack;

[0008] The thermal runaway alarm strategy of the thermal runaway alarm detection device is as follows:

[0009] a) BPS monitors the peak pressure P in the pressure relief cavity max When P exceeds P1, the pressure sharp change rate exceeds ΔP1;

[0010] b) NTC monitors the peak temperature T in the pressure relief cavity max When T exceeds T, the temperature sharp change rate exceeds ΔT1, and lasts for t;

[0011] c) The voltage sharp change rate of any single battery exceeds ΔU;

[0012] When conditions a and c are met at the same time, or conditions b and c are met at the same time, the thermal runaway alarm detection device determines that thermal runaway occurs in the battery pack, and sends an alarm signal.

[0013] As a preferred, P1 is 110 kpa, and ΔP1 is 2 Mpa / s.

[0014] As a preferred, T is 80℃, ΔT1 is 1℃ / s, and the duration t is 3s.

[0015] As a preferred, ΔU is 25%.

[0016] As a preferred, the thermal runaway alarm detection device sends a thermal runaway alarm signal, opens the electromagnetic valve, and activates the trigger device, and the total time t1 required is not more than 0.5s, and the dry ice and high-pressure nitrogen gas injection time t2 in the gas storage tank is not more than 0.15ms.

[0017] As a preferred, the trigger mechanism comprises a bracket I, a reset spring, a bracket II, a positioning pin shaft, a support rod and a one-way valve, the one-way valve and the high-pressure gas pipe I form a normally closed gas path, the one-way valve end is attached to a spherical locking pin and is arranged beside the gas storage tank; the lower end of the bracket I is fixed with the box, and the upper end is hinged with one end of the support rod through the positioning pin shaft; the other end of the support rod is provided with the one-way valve above and the electromagnetic valve below; the electromagnetic valve is powered on to attract the magnet block on the surface of the support rod, and the one-way valve is communicated with the high-pressure gas pipe I and the high-pressure gas pipe II; the bracket II is arranged in the middle of the support rod, and the reset spring is arranged between the support rod and the bracket I.

[0018] As preferred, the one-way valve end is attached to a ball-type locking pin, which is welded on the surface of the support rod and moves with the support rod.

[0019] As preferred, the reset spring is arranged between the support rod and the bracket I and is in a stretched state, and the spring stiffness is not less than 10 KN / mm.

[0020] As preferred, the maximum size of the gas tank is not more than 82 mm, the weight of the dry ice stored in the tank is 2.0 kg, the maximum diameter of the dry ice particles is not more than 5 microns, the pressure of the high-pressure nitrogen gas is 3.6 Mpa, and the dry ice spraying completion time is not more than 0.15 ms.

[0021] As preferred, the box and the battery tray form a pressure relief chamber, the net volume of the pressure relief chamber is 6.1 L, the effective pressure relief area of the pressure relief port is 3900 mm 2 The flow resistance from the gas outlet of the high-pressure gas pipe II to the pressure relief chamber to the explosion-proof valve is less than 4 kpa.

[0022] The present application has the following advantages:

[0023] (1) When the battery pack thermal runaway alarm detection device (BMS) detects that a certain cell is out of control, the electromagnetic valve opens the ball-type lock, the one-way valve opens, and the high-pressure nitrogen gas in the gas tank sprays the superfine powder dry ice into the pressure relief chamber of the battery pack, the original air in the pressure relief chamber is discharged into the atmosphere through the explosion-proof valve of the battery pack, the air volume ratio in the pressure relief chamber of the battery pack is limited to below 20%, which is beyond the explosion limit range of the mixed flammable gas, and plays a role in inhibiting explosion;

[0024] (2) After the BMS detects thermal runaway, the response time of the trigger mechanism is less than 0.5 s, and the time interval from the battery determining out of control to releasing mixed flammable gas is more than 3 s, so the trigger mechanism can ensure that the trigger action is completed before the battery releases mixed flammable gas; the high-pressure nitrogen gas stored in the gas tank can be sprayed in 0.15 ms, the dry ice spraying rate is more than 90%, and the dry ice can fill the entire pressure relief chamber of the battery pack in 10 ms; the spray pipe openings of the high-pressure gas pipe are distributed on the left and right sides of the pressure relief chamber and are opposite to the explosion-proof valve of the battery pack, so that the dry ice and nitrogen gas can quickly fill the entire pressure relief chamber of the battery pack, and the original air in the pressure relief chamber can be quickly discharged;

[0025] (3) The electromagnetic valve is only powered on after the BMS detects thermal runaway, and is in a power-off state in other states, so the function loss is minimized;

[0026] (4) The gases for inhibiting mixed combustible gas explosion are dry ice and nitrogen, and will not cause environmental pollution when leaking and releasing. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structural schematic diagram of the present application;

[0028] Figure 2 is a structural schematic diagram of the thermal runaway device arranged in the battery pack;

[0029] Figure 3 is Figure 2 A-A sectional view of the present application;

[0030] Figure 4 is a thermal runaway alarm strategy of the thermal runaway alarm detection device;

[0031] In the figure: 1, gas storage tank; 2, high-pressure gas pipe I; 3, support I; 4, reset spring; 5, support II; 6, positioning pin shaft; 7, support rod; 8, one-way valve; 9, electromagnetic valve; 10, high-pressure gas pipe II; 11, box body; 12, battery tray; 13, fixed threaded hole; 14, cylindrical battery cell; 15, foaming glue; 16, BDU; 17, thermal runaway alarm detection device; 18, cross beam; 19, explosion-proof valve. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] As Figures 1-4As shown, the cylindrical lithium battery pack thermal runaway explosion suppression device of the present application comprises a gas storage tank 1, a high-pressure gas pipe I 2, a support I 3, a return spring 4, a support II 5, a positioning pin shaft 6, a support rod 7, a one-way valve 8, a solenoid valve 9, a high-pressure gas pipe II 10, and a thermal runaway alarm detection device 17 (BMS), etc. The gas storage tank 1, the high-pressure gas pipe I 2 and the high-pressure gas pipe II 10 are used to store dry ice and high-pressure nitrogen, and are arranged on one side of the battery pack which is not a module. The trigger mechanism is composed of the support I 3, the return spring 4, the support II 5, the positioning pin shaft 6, the support rod 7 and the one-way valve 8, etc. The one-way valve 8 and the high-pressure gas pipe I 2 form a normally closed gas path, and the end of the one-way valve 8 is attached to the spherical locking pin and arranged beside the gas storage tank 1. The solenoid valve 9 is arranged below the support rod 7 and is in an energized state only under abnormal conditions to attract the magnet block on the surface of the support rod 7. The gas storage tank, the trigger mechanism, the solenoid valve and other components together form the explosion suppression device, which is placed in the box 11. The two gas outlet pipes of the high-pressure gas pipe II 10 pass through the cross beam 18 and are arranged in the pressure relief chamber of the box 11.

[0034] The gas storage tank 1 is connected with the one-way valve 8 of the trigger mechanism through the high-pressure gas pipe I 2, and the one-way valve 8 is communicated with the pressure relief chamber of the box 11 through the high-pressure gas pipe II 10. The solenoid valve 9 is in a normally closed state and is connected with the thermal runaway alarm detection device 17 in the battery pack. In combination with Figure 4 As shown, the thermal runaway alarm strategy of the thermal runaway alarm detection device 17 is as follows:

[0035] a) BPS monitors the peak pressure P in the pressure relief chamber max When P exceeds P1 and the pressure sharp change rate exceeds ΔP1; wherein P1 is 110 kpa and ΔP1 is 2 Mpa / s;

[0036] b) NTC (temperature sensor) monitors the peak temperature T in the pressure relief chamber max When T exceeds T and the temperature sharp change rate exceeds ΔT1 for t; wherein T is 80℃, ΔT1 is 1℃ / s, and t is 3s;

[0037] c) The voltage sharp change rate of any one single battery exceeds ΔU, and ΔU is 25%;

[0038] When conditions a and c are met at the same time, or conditions b and c are met at the same time, the thermal runaway alarm detection device determines that thermal runaway occurs in the battery pack, and an alarm signal is sent.

[0039] In this embodiment, the thermal runaway alarm detection device 17 sends a thermal runaway alarm signal, opens the solenoid valve 9, and the total time t1 required to activate the trigger device does not exceed 0.5s, and the dry ice and high-pressure nitrogen in the gas storage tank are sprayed for a time t2 of not more than 0.15ms.

[0040] In this embodiment, the trigger mechanism includes support I3, reset spring 4, support II 5, positioning pin shaft 6, support rod 7 and one-way valve 8, one-way valve 8 and high-pressure gas pipe I2 form a normally closed gas path, the end of one-way valve 8 is attached to the spherical locking pin, and is arranged beside the gas storage tank; the lower end of support I3 is fixed with the box body 11, and the upper end is hinged with one end of support rod 7 through positioning pin shaft 6; the other end of support rod 7 is provided with one-way valve 8 above and electromagnetic valve 9 below; electromagnetic valve 9 is powered to attract the magnet block on the surface of support rod 7, and one-way valve 8 connects high-pressure gas pipe I2 and high-pressure gas pipe II 10; support II 5 is arranged in the middle of support rod 7, and reset spring 4 is arranged between support rod 7 and support I3.

[0041] In this embodiment, the end of one-way valve 8 is attached to the spherical locking pin, and the spherical locking pin is welded on the surface of support rod 7 and moves with support rod 7.

[0042] In this embodiment, reset spring 4 is arranged between support rod 7 and support I3 and is in a stretched state, and the spring stiffness is not less than 10KN / mm.

[0043] In this embodiment, the maximum external dimension of the gas storage tank 1 is not more than 82mm, the weight of dry ice stored in the tank is 2.0kg, the maximum diameter of dry ice particles is not more than 5 microns, the pressure of high-pressure nitrogen gas is 3.6Mpa, and the dry ice spraying completion time is not more than 0.15ms.

[0044] In this embodiment, the box body 11 and the battery tray 12 form a pressure relief chamber, the net volume of the pressure relief chamber is 6.1L, the effective pressure relief area of the pressure relief port is 3900mm 2 The flow resistance from the gas outlet of high-pressure gas pipe II to the pressure relief chamber to the explosion-proof valve is less than 4kpa.

[0045] In this embodiment, the pipe joint of one-way valve 8 and high-pressure gas pipe I2 is a taper thread joint, and double sealing ring structure is used near the joint.

[0046] In this embodiment, the thermal runaway alarm detection device 7 (BMS) is composed of three parts of pressure sensor (BPS), temperature sensor (NTC) and voltage signal (U).

[0047] When the BMS detects that a certain battery cell is out of control, the electromagnetic valve 9 opens the ball-type lock, the one-way valve 8 opens, and the high-pressure nitrogen gas in the gas tank 1 sprays the superfine dry ice into the pressure relief cavity of the battery pack, the response time of the trigger mechanism is less than 0.5s, and the time interval from the determination of the battery pack being out of control to the release of the mixed combustible gas is more than 3s, so the trigger mechanism can ensure that the trigger action is completed before the battery pack releases the mixed combustible gas when it is out of control; the high-pressure nitrogen gas stored in the gas tank 1 can be sprayed in 0.15ms, the dry ice spraying rate is more than 90%, and the dry ice can fill the entire pressure relief cavity of the battery pack in 10ms; the spray pipe openings of the high-pressure gas pipe II are distributed on the left and right sides of the pressure relief cavity and opposite the explosion-proof valve of the battery pack, so the dry ice and nitrogen gas can quickly fill the entire pressure relief cavity of the battery pack and quickly discharge the original air in the pressure relief cavity, so that the volume ratio of the air in the pressure relief cavity of the battery pack is limited to less than 20%, which is beyond the explosion limit range of the mixed combustible gas, thereby playing a role in inhibiting explosion.

[0048] Finally, it should be pointed out that the above embodiments are only more representative examples of the present application. Obviously, the present application is not limited to the above embodiments, and there can be many variations. Any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments shall be considered to be within the protection scope of the present application.

Claims

1. A device for suppressing thermal runaway and explosion of a cylindrical lithium battery pack, characterized in that: It includes a triggering mechanism, a solenoid valve (9) and a gas storage tank (1). The gas storage tank (1) is connected to the one-way valve (8) of the triggering mechanism through a high-pressure gas pipe I (2). The one-way valve (8) is connected to the pressure relief chamber of the housing (11) through a high-pressure gas pipe II (10). The solenoid valve (9) is normally closed and is connected to the thermal runaway alarm detection device (17) in the battery pack. The thermal runaway alarm strategy of the thermal runaway alarm detection device (17) is as follows: a) BPS monitors the peak pressure in the pressure relief chamber. The pressure change rate exceeds ΔP1; P1 is 110 kPa, and ΔP1 is 2 MPa / s. b) NTC monitoring of peak temperature within the pressure relief chamber When the temperature exceeds T, the rate of temperature change exceeds ΔT1 and lasts for t; when T is 80℃, ΔT1 is 1℃ / s and lasts for t for 3s. c) The voltage sag rate of any single cell exceeds ΔU, where ΔU is 25%; When conditions a and c are met simultaneously, or conditions b and c are met simultaneously, the thermal runaway alarm detection device (17) determines that thermal runaway has occurred in the battery pack and issues an alarm signal. The thermal runaway alarm detection device (17) sends out a thermal runaway alarm signal, opens the solenoid valve (9), and activates the triggering device. The total time required is... The time interval between the battery pack's determination of runaway and the release of the mixed flammable gas exceeds 3 seconds, and the triggering mechanism can ensure that the triggering action is completed before the battery releases the mixed flammable gas due to runaway; the dry ice and high-pressure nitrogen injection time in the gas storage tank (1) Within 0.15ms, the dry ice ejection rate exceeds 90%, and the dry ice can fill the entire pressure relief chamber of the battery pack within 10ms.

2. The cylindrical lithium battery pack thermal runaway suppression device according to claim 1, characterized in that: The triggering mechanism includes bracket I (3), a return spring (4), bracket II (5), a positioning pin (6), a support rod (7), and a one-way valve (8). The one-way valve (8) and the high-pressure air pipe I (2) form a normally closed air circuit. The end of the one-way valve (8) is attached to a ball-shaped locking pin and is located next to the air tank (1). The lower end of the bracket I (3) is fixed to the box body (11), and the upper end is hinged to one end of the support rod (7) through the positioning pin (6). The other end of the support rod (7) is provided with a one-way valve (8) above and a solenoid valve (9) below. When the solenoid valve (9) is energized, it attracts the magnet block on the surface of the support rod (7). The one-way valve (8) connects the high-pressure air pipe I (2) and the high-pressure air pipe II (10). The bracket II (5) is located in the middle of the support rod (7), and a return spring (4) is provided between the support rod (7) and the bracket I (3).

3. The cylindrical lithium battery pack thermal runaway suppression device according to claim 2, characterized in that: The end of the one-way valve (8) is fitted with a ball-shaped locking pin, which is welded to the surface of the support rod (7) and moves with the support rod (7).

4. The cylindrical lithium battery pack thermal runaway suppression device according to claim 2, characterized in that: The reset spring (4) is arranged between the support rod (7) and the bracket I (3) and is in a stretched state, with a spring stiffness of not less than 10KN / mm.

5. The cylindrical lithium battery pack thermal runaway suppression device according to claim 1, characterized in that: The maximum external dimensions of the gas storage tank (1) are no more than 82 mm, the weight of the dry ice stored in the tank is 2.0 kg, the maximum diameter of the dry ice particles is no more than 5 micrometers, the pressure of the high-pressure nitrogen is 3.6 MPa, and the dry ice spraying time is no more than 0.15 ms.

6. The cylindrical lithium battery pack thermal runaway suppression device according to claim 1, characterized in that: The housing (11) and the battery tray (12) together form a pressure relief chamber with a net volume of 6.1L and an effective pressure relief area of ​​3900mm². 2 The flow resistance from the outlet of the high-pressure air pipe II (10) to the pressure relief chamber to the explosion-proof valve is less than 4 kPa.

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