Particle separator for battery pack and battery pack having particle separator

Abstract

The present invention relates to a particle separator (100) which is configured to separate solid particles from a particle-battery gas mixture introduced at an inlet (8) at an overpressure and to relieve the pressure of the battery gas at an outlet (111). The particle separator (100) has a gas channel which is spirally wound along the axial direction z and which connects the inlet (8) fluid to the outlet (111). The gas channel has a particle discharge mechanism (112) which is open in the radial direction y and configured for the passage of particles at the outlet side. The present invention also relates to a battery housing (2) having such a particle separator (100), a battery pack (1) having at least one battery module (3) encapsulated in the battery housing (2), and a motor vehicle which is at least partially powered by the battery pack (1).

Description

Technical Field

[0001] The invention relates to a particle separator for a battery pack according to the preamble of claim 1. The invention also relates to a battery housing having such a particle separator according to the preamble of claim 6, a battery pack comprising such a battery housing with battery modules enclosed therein according to claim 7, and a motor vehicle comprising such a battery pack according to claim 9. Background Art

[0002] Document DE 10 2013 204 585 A1 proposes a battery pack for use, for example, in electric or hybrid vehicles. In the event of degassing of individual battery cells, for example due to overload or thermal overload, gas is released from their interior by an overpressure mechanism, a dedicated free space is provided in the battery pack housing, into which the released gas can be decompressed and at the same time its temperature and pressure can be reduced. The gas is then released from the battery pack housing to the outside via an overpressure relief device. The gas now flows through a particle separator, for example in the form of a cyclone separator or a surface filter with a fiber composite or an open-pored sponge-like structure, which is provided in the overpressure relief device. Particles contained in the gas, such as graphite dust, can be filtered out when flowing through the particle separator in order to reduce the risk of explosion, for example caused by hot particles in the outflowing gas. Summary of the invention

[0003] The present invention is based on the object of specifying an improved particle separator for a battery pack. The present invention is also based on the object of specifying an improved battery housing for a battery pack, an improved battery pack and an improved motor vehicle.

[0004] According to the invention, this object is achieved with respect to the particle separator by a particle separator having the features of claim 1. With respect to the battery housing, the battery pack and the motor vehicle, this object is achieved with respect to the features of claim 6, claim 7 or claim 9.

[0005] Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0006] A particle separator is provided for separating solid particles from a particle-battery gas mixture and has an inlet provided for introducing an over-pressurized particle-battery gas mixture. The particle separator has an outlet provided for depressurizing the battery gas.

[0007] According to the present invention, the particle separator has a gas channel which is spirally wound along the axial direction and connects the inlet with the outlet fluid. At the outlet side, the particle separator has a particle discharge mechanism which is opened in the radial direction, that is, in the direction perpendicular to the axial extension and is set up for particles to pass through.

[0008] Advantageously, the separation of the battery gases from the particles reduces their ignition probability. In particular, it is to be prevented that hot particles, such as graphite particles or metal particles, which are released when a battery cell is thermally overloaded, ignite the battery gases when they escape into the environment.

[0009] Conventional particle-battery gas separators separate the particle-battery gas mixture by acceleration, wherein the heavier particles are not discharged as quickly as the lighter battery gas due to their greater inertia. Here, the particles fall at any point along the acceleration path.

[0010] In comparison, the proposed particle separator has the advantage that the particles are guided together with the battery gas through the spiral gas channel and, in addition to an axial linear velocity component directed in the longitudinal direction of the spiral gas channel, also have an angular velocity component which is oriented tangentially to the spiral shape of the gas channel and exerts a centrifugal force on the moving particle-battery gas mixture. Under the action of the centrifugal force, the heavier particles move radially outward, i.e. perpendicularly to the linear velocity component and perpendicularly to the angular velocity component, and simultaneously displace the lighter battery gas radially inward.

[0011] Through the radial openings of the particle discharge, the particles flow out here and can be collected and contained, while the battery gas can flow out axially and be relieved substantially without deceleration. Advantageously, the flow resistance of the proposed particle separator is reduced compared to the prior art solutions. This makes it possible to achieve a very efficient pressure relief of the particle-battery gas mixture discharged under overpressure through the particle separator.

[0012] In one embodiment of the present invention, the gas channel is formed by a worm arranged in the standpipe. The worm has a worm helix which spirals around an axial worm axis extending in the longitudinal direction of the standpipe.

[0013] The stand pipe has rifling protruding radially inwardly toward the worm shaft and winding in the longitudinal axial direction. The rifling is wound corresponding to the worm helix.

[0014] The standpipe is gas-permeable and sealed with a screen plate on the inlet side and widens in a funnel shape in an outlet bell on the outlet side. The particle discharge is arranged as a radial slot in the circumference of the standpipe in the area of ​​the outlet bell.

[0015] The spiral gas channel can be formed very easily by means of the worm helix and the correspondingly spiral rifling. The worm and the stand pipe can be designed to be detachable from one another. This allows for simple and inexpensive production and installation. Furthermore, the formation of the spiral gas channel by means of the worm offers the advantage that a large clear inner diameter of the stand pipe is available for the flow of the particle-battery gas mixture, thereby achieving good pressure relief through the particle separator.

[0016] In one embodiment, the worm helix and the rifling each have approximately three turns on the inner side of the standpipe circumference. An increase in the number of turns of the worm helix leads to an increase in radial acceleration and thus also to an improved separation of particles from the cell gas, but here the degree of improvement achieved by the additional turns gradually decreases with increasing length of the worm helix. A number of approximately three turns has proven to be the best compromise between a good separation effect of the particle separator and the installation space requirement, which is primarily determined by its axial length.

[0017] In one embodiment, the particle discharge extends over the entire spiral height of the worm spiral and has a radial opening, so that the particles displaced radially outward are ejected as completely as possible and thus a high separation effect of the particle separator is achieved.

[0018] In one embodiment, the screen plate is designed to intercept particles with a cross section of at least 1.5 mm. By intercepting larger, and therefore heavier, particles with a greater inertia, a shorter configuration of the particle separator and an improved passage of the particle-battery gas mixture are allowed. At the same time, sufficiently large screen meshes allow a low flow resistance and thus an efficient pressure relief through the particle separator. Screen meshes with a cross section of approximately 1.5 mm have proven to be a good compromise between an excellent separation action and a low flow resistance.

[0019] The battery housing is designed for hermetically sealing at least one battery module and comprises an insulating lining with at least one opening provided therein, which is designed for fluidly connecting the interior of the battery housing (2) to its environment when a predetermined overpressure limit value is exceeded.

[0020] The particle separator according to the present invention is arranged in the at least one gap. At least one separation chamber is reserved in the insulating liner, and the separation chamber is in fluid communication with the particle discharge mechanism of the at least one particle separator.

[0021] After a battery cell of at least one battery module has been thermally overloaded, the particle-battery gas mixture that forms is discharged through the particle separator when a predetermined overpressure limit value is exceeded. In this process, particles that could still be hot and ignite the battery gas flowing out into the environment are guided by the particle discharge into the smooth-flowing separation chamber. As a result, the ignition probability of the outflowing battery gas is significantly reduced.

[0022] The battery pack comprises a battery housing according to the invention with a particle separator according to the invention, wherein at least one battery module is enclosed in the battery housing. The operating safety of such a battery pack can be improved by preventing ignition of the battery gases that escape in the event of a thermal overload.

[0023] In one embodiment, the at least one battery module comprises at least one lithium-ion battery cell, which has a high energy density and a long service life and emits a particle-battery gas mixture under thermal overload, the ignition probability of which can be effectively reduced by the particle separator of the present invention.

[0024] Furthermore, a motor vehicle, preferably an electric vehicle, is proposed, which is at least sometimes operated and / or powered by such a battery pack. Such a motor vehicle has a high degree of operating safety. In particular, an electric vehicle designed in this way meets the current legal, regulatory and / or standard safety regulations regarding the period between the detection of a thermal overload and the start of battery combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The embodiments of the present invention are explained in detail below with reference to the drawings, wherein:

[0026] Figure 1 Schematically showing a cross section of a battery pack,

[0027] Figure 2 Schematically showing a perspective view of the inlet side of the insulating liner,

[0028] Figure 3 Schematically showing a perspective view of the outlet side of the insulating liner,

[0029] Figure 4 A perspective view schematically showing an axial separator,

[0030] Figure 5 Schematically showing a perspective view of a disassembled axial separator with a riser and a worm,

[0031] Figure 6 A perspective view schematically showing a detail of the riser,

[0032] Figure 7 Schematically showing the outlet side view of the axial separator,

[0033] Figure 8 Shown are computer simulation results with eight hundred particles where the axial separator is inverted. DETAILED DESCRIPTION

[0034] Parts that correspond to one another are provided with the same reference symbols in all the figures.

[0035] Figure 1 The schematic cross-sectional view of a battery pack 1 with a battery housing 2 is shown. The battery housing 2 is gas-tight. A battery module 3 is arranged inside the battery housing 2 .

[0036] In the event of damage to the battery pack 1 or the battery module 3 , battery gases may form, which should be dissipated in a controlled manner to the environment in order to prevent an explosion of the battery pack 1 . The battery gases are discharged from the battery housing 2 along the insulating lining 4 .

[0037] The insulating lining 4 has a gap 5 between the interior of the battery housing 2 and its environment, which is provided for discharging battery gases and is explained below. The gap is sealed airtightly by a fuse diaphragm 6 and / or a diaphragm valve 7. If the overpressure in the battery housing 2 reaches a predetermined limit value, the fuse diaphragm 6 ruptures and / or the diaphragm valve 7 opens. Thus, the pressure relief of the overpressured battery gases can be achieved through the insulating lining 4.

[0038] Figure 2 The insulating lining 4 is schematically shown in a perspective view from the housing interior of the battery housing 2. A ruptured fuse diaphragm 6 or an open diaphragm valve 7 allows the battery gas to be discharged from the inlet 8 in the axial direction z to the external environment of the battery housing 2 through the axial separator 100. The axial separator 100 is arranged in a cylindrical recess 5 through the insulating lining 4. On the inlet side, the axial separator 100 is closed by a screen plate 121. The arrangement and mode of operation of the screen plate 121 will be explained in detail below.

[0039] Figure 3 The insulating lining 4 is schematically shown in a perspective view from the opposite perspective, ie from the surroundings of the battery housing 2. The axial separator 100 has an outlet bell 111 widened in a bell shape on the outlet side, through which the outflowing battery gas is discharged to the surroundings.

[0040] A radial slot-shaped particle discharge mechanism 112 is provided in the outlet bell mouth 111. The particle discharge mechanism 112 is provided for discharging solid particles which are carried by the outflowing battery gas and are small enough to pass through the sieve plate 121 on the inlet side.

[0041] As will be explained in detail below, the particles are guided through the particle exhaust mechanism 112 in the radial direction y, while the battery gas flows out in the axial direction z. The discharged particles are guided into the separation chamber 10 left in the insulating liner 4 through the particle channel 9 designed as a fluid communication mechanism between the particle exhaust mechanism 112 and the separation chamber 10.

[0042] Figure 4 The axial separator 100 is shown in a perspective view from the outside. The battery gas flows through the axial separator 100 in the axial direction z, and the battery gas flows in at the inlet side end of the battery housing 2 closed by the sieve plate 121 and flows out at the outlet side end closed by the outlet bell mouth 111 .

[0043] A cylindrical hollow standpipe 110 is provided between the sieve plate 121 and the outlet bell mouth 111. Figure 4The worm 120 is not visible in the figure. At the sleeve where the outlet bell mouth 111 is connected to the vertical pipe 110, a particle discharge mechanism 112 is reserved in the circumference of the axial separator 100. The particle discharge mechanism 112 extends along the circumference of the axial separator 100 in the form of a long slit, occupying a length of approximately one third to one sixth of the total circumference.

[0044] Within the length range of the particle discharge mechanism 112 , the outer peripheral surface of the outlet bell mouth 111 is retracted and bulges more obviously than the rest of the outlet bell mouth 111 .

[0045] The axial separator 100 is preferably made of a lightweight, extremely heat-resistant and pressure-resistant material. In particular, phenol-formaldehyde resins such as PF 1110.

[0046] Figure 5 The axial separator 100 is shown in a disassembled state, that is, the worm 120 is removed. A locking groove 113 is axially provided at the inlet side end of the standpipe 110, which is designed to correspond to the locking protrusion 122 protruding from the screen plate 121 in the radial direction y.

[0047] The removed worm 120 comprises a worm helix 123 with a worm axis 124 extending in the longitudinal direction of the worm 120, i.e. in the axial direction z. Here, the worm helix 123 has approximately 2.5 full turns. However, it is also possible for the worm helix 123 to have a different number of turns. The worm helix 123 preferably has approximately three turns with an axial extension of approximately 100-120 mm.

[0048] At the inlet side, the worm shaft 124 is fixedly connected to the sieve plate 121 arranged vertically therewith. In the installed state, the locking protrusion 122 of the sieve plate 121 is locked in the locking groove 113 of the stand pipe 110. The worm 120 and the stand pipe 110 together with the particle discharge mechanism 112 are thus fixed together in a relatively rotationally fixed manner in the installed state.

[0049] At the outlet-side end, the worm shaft 124 protrudes beyond the worm 120 in the axial direction.

[0050] Figure 6 The view from the inlet side, i.e. the end opposite to the outlet bell mouth 111, shows the standpipe 110. A spiral rifling 114 is arranged on the inner wall of the standpipe 110. The spiral rifling 114 protrudes radially inward from the inner wall of the standpipe 110. The turns of the rifling 114 are designed to be the same in direction and pitch as the turns of the worm helix 123 of the worm 120. In the locked installation position, i.e., when the locking protrusion 122 of the screen plate 121 is locked in the locking groove 113, the worm helix 123 and the rifling 114 are exactly opposite in the radial direction y.

[0051] A circular arc segment-shaped protrusion 115 is provided at the outlet side end of the outlet bell mouth 111, which protrudes radially inward to the center of the standpipe 110 and contracts to a point. A worm bearing 116 is provided at the contracted inner end of the protrusion 115, and the worm bearing has a hole for accommodating the outlet side protruding end of the worm shaft 124.

[0052] The outer arc of the arc segment-shaped convex piece 115 is connected to the outlet side end of the peripheral surface of the outlet bell mouth 111 and extends approximately on the peripheral surface of the outlet bell mouth 111 to occupy the same angular range (or circumferential portion) as the particle discharge mechanism 112. In other words, the particle discharge mechanism 112 and the convex piece 115 are arranged to be aligned with each other in the axial direction z. The outlet bell mouth 111 is therefore covered in the region of the convex piece 115, that is, on the outlet side of the particle discharge mechanism 112.

[0053] The worm bearing 116 arranged on the lug 115 together with the locking groove 113 ensures that the worm 120 is accommodated in the standpipe 110 in a rotationally fixed manner on both sides. The lug 115 exerts a reverse resistance on the axial flow, which causes a local increase in the flow pressure of the outflowing battery gas in the area between the lug 115 and the particle discharge device 112.

[0054] Figure 7 An outlet side top view of the standpipe 110 is shown with the outlet bell 111 attached and the worm 120 installed.

[0055] The working mode of the axial separator 100 will be explained below. In the event of thermal overload, the battery module 3 may burst and release battery gas and hot particles such as graphite particles or metal particles at the same time, which may form an ignitable mixture. The proposed axial separator 100 separates the particles from the outflowing battery gas and thus reduces the probability of ignition of the mixture.

[0056] Larger particles in the particle-cell gas mixture are intercepted by the screen 121 and do not enter the axial separator 100 and thus remain inside the cell housing 2. The mesh size of the screen 121 is preferably selected in such a way that particles having a diameter of 1.5 mm or more are intercepted.

[0057] Cell gases and particles with a diameter smaller than the aperture size of the sieve plate 121 enter the axial separator 100 and are guided through the axial separator 100 along a spiral path in the axial direction z by the worm helix 123 and the opposing and correspondingly designed rifling 114 at the edge of the standpipe 110 .

[0058] The spiral guidance of the particle-battery gas mixture also creates a vortex on the inlet side of the sieve plate 121. As a result, the separated large particles are guided away from the sieve plate 121 or are dispersed and clogging of the sieve plate 121 is avoided.

[0059] The sieve plate 121 may also be designed to be convex, which helps large particles deposited thereon to be guided away or dispersed.

[0060] Furthermore, the forced spiral flow of the particle-battery gas mixture causes its decomposition, wherein, under the action of centrifugal force, the heavier particles move radially outward, i.e., toward the inner wall of the standpipe 110, and simultaneously displace the lighter battery gas radially inward, i.e., toward the worm shaft 124. The radial decomposition is enhanced in the axial direction z and the separation between the particles flowing at the inner wall of the outlet bell mouth 111 and the battery gas displaced into the outlet bell mouth 111 is achieved to the greatest extent at the outlet bell mouth 111.

[0061] The centrifugal force acting in the radial direction y also causes the particles to flow out in the radial direction through the slot-shaped particle discharge mechanism 112, as shown in FIG. Figure 7 The outflow of the particles is assisted by the increased flow pressure at the particle discharge 112 by means of the fins 115 .

[0062] The discharged particles are pressed into the flow-smoothing region of the separation chamber 10 through the particle channel 9 and collected there. The battery gas mixture purified in this way, which still only contains very small and light particles with a diameter of generally between 10 μm and 100 μm, is depressurized through the outlet bell 111, passes through the downstream fuse diaphragm 6 and / or the downstream diaphragm valve 7 and is discharged to the environment of the battery housing 2. Since the heating time of the particles decreases with their size, the still very small and light particles contained extinguish when flowing out into the environment and can no longer ignite the battery gas.

[0063] It has been shown that when the battery gases are guided out of the battery housing 2 through the axial separator 100 of the present invention, the period between thermal overload of the battery module 3, for example caused by a metal nail piercing the battery pack 1, and battery combustion can be extended. Thus, for example, in a preliminary test without the particle separator of the present invention, it was determined that the battery gases were ignited by particles in less than five minutes. In the test with the particle separator of the present invention, however, no ignition of the battery gases by particles was detected. Instead, the ignition of the battery gases always occurs after more than 5 minutes due to other ignition sources, such as high-voltage spark discharges. A longer period that meets legal regulations and standards is thus provided for warning the user, such as a passenger of an electric vehicle powered by such a battery pack 1. One advantage of the present invention therefore lies in the improved safety of use and the expanded scope of application of the battery pack 1 with the proposed axial separator 100.

[0064] Conventional particle-battery gas separators separate the particle-battery gas mixture by acceleration, where the lighter battery gas is discharged more quickly due to the greater inertia of the heavier particles. Here, the particles fall at any point along the acceleration path. In contrast, one advantage of the present invention is that the particles are collected and finally deposited in the encapsulation area, i.e., the separation chamber 10, so that the occurrence or spread of flames can be easily prevented.

[0065] A computer simulation was performed to test the effectiveness of the axial separator 100. For this purpose, the software StarCCM+ was used and a 3D Eulerian-Lagrangian gas-particle simulation was performed.

[0066] The following boundary conditions were assumed in the computer simulation: static simulation, gas mass flow rate of 25 g / s, gas inlet temperature of 300 °C (worst case scenario), adiabatic wall temperature, initial particle temperature of 1000 °C, particle materials of graphite and NMC (lithium-nickel-manganese-cobalt oxide) and copper, and particle shape of spherical.

[0067] The following results were obtained in the computer simulation: the pressure drop in the axial separator 100 was 340 mbar, the maximum Mach number was 0.54, and the separation rate for particles with a diameter of 50-1000 μm was 100%.

[0068] Figure 8 Schematically show this computer simulation result with eight hundred particles. In this illustration, a part of the axial separator 100 is shown. Here, the axial separator 100 is inverted, that is, the outlet bell mouth 111 is arranged on top, below it is the riser 110, and below the riser is the inlet 8. The separation chamber 10 is located on its left side. The path of the particles is shown in the form of multiple lines (motion trajectory 800), which schematically shows a total of eight hundred motion trajectories simulated in the Euler-Lagrangian gas-particle simulation. From the illustration, it can be seen how the particles enter the axial separator 100 "from below" at a lower speed of less than 3,000m / s, then accelerate "upward" to more than 12,000m / s in the z direction when flowing through the spirally wound gas channel, and finally leave from the axial separator 100 in the y direction and enter the separation chamber 10, where they suddenly decelerate and finally stop, that is, accumulate. As already described above, for particles having a diameter of 50-1000 microns, the separation rate is 100%.

[0069] It should be noted that the installation position of the axial separator 100 in the motor vehicle can be arbitrary, i.e. the axial separator can in principle be in any spatial orientation in the motor vehicle. However, the following limitation applies, namely that in the installation position it should be ensured that the particles accumulated in the separation chamber 10 do not fall back into the axial separator through the slot-shaped particle discharge 112. As a result, almost any installation position means an improvement in the design freedom with regard to the flexible and full utilization of the narrow installation space available in the motor vehicle.

[0070] Reference numerals list

[0071] 1 Battery Pack

[0072] 2 Battery housing

[0073] 3 Battery Module

[0074] 4 Insulation lining

[0075] 5. Gap

[0076] 6. Fuse diaphragm

[0077] 7 Diaphragm valve

[0078] 8 Entrance

[0079] 9 Particle Channels

[0080] 10 Separation chamber

[0081] 100 Axial separator, particle separator

[0082] 110 Riser

[0083] 111 Exit bell, exit

[0084] 112 Particle discharge mechanism

[0085] 113 Locking groove

[0086] 114 Rifling

[0087] 115 Tab

[0088] 116 Worm bearing

[0089] 120 Worm

[0090] 121 Screen Plate

[0091] 122 Locking protrusion

[0092] 123 Worm helix

[0093] 124 Worm shaft

[0094] z-axis

[0095] y Radial

Claims

1. A particle separator (100) which is designed to separate solid particles from a particle-battery gas mixture introduced at an inlet (8) at an overpressure and to relieve the battery gas at an outlet (111), in, The particle separator (100) has a gas channel that is spirally wound in the axial direction (z), and the gas channel connects the inlet (8) to the outlet (111). The gas channel has a particle discharge mechanism (112) that is opened in the radial direction (y) and is set up for particles to pass through at the outlet side end. It is characterized in that the gas channel is formed by a worm (120) provided in a standpipe (110) and having a worm helix (123) spiraling around an axial worm shaft (124), wherein the standpipe (110) has rifling (114) protruding radially inward and spiraling corresponding to the worm helix (123), wherein the standpipe (110) is closed in an air-permeable manner on the inlet side by a sieve plate (121) and widens in a funnel-shaped manner in an outlet bell mouth (111) on the outlet side, and wherein the particle discharge mechanism (112) is arranged as a radial slot in the circumference of the standpipe (110) in the area of ​​the outlet bell mouth (111).

2. The particle separator (100) according to claim 1, characterized in that: The worm helix (123) and the rifling (114) each have three turns.

3. The particle separator (100) according to claim 1 or 2, characterized in that: The particle discharge mechanism (112) is designed to extend through the entire spiral height of the worm spiral (123) and have a radial opening.

4. The particle separator (100) according to claim 1 or 2, characterized in that: The screen plate (121) is designed to intercept particles having a cross-section of at least 1.5 mm.

5. The particle separator (100) according to claim 1 or 2, characterized in that: The sieve plate (121) is configured in a convex shape.

6. A battery housing (2) configured to hermetically seal at least one battery module (3), the battery housing comprising an insulating lining (4) together with at least one notch (5) provided in the insulating lining, the notch being configured to connect the inner cavity fluid to the environment of the battery housing when a prescribed overpressure limit value in the inner cavity of the battery housing (2) is exceeded, characterized in that: A particle separator (100) according to any one of claims 1 to 5 is provided in the at least one notch (5), and at least one separation chamber (10) is reserved in the insulating lining (4) and is fluidically connected to a particle discharge mechanism (112) of the at least one particle separator (100).

7. A battery pack (1) comprising a battery housing (2) according to claim 6 together with at least one battery module (3) enclosed in the battery housing (2).

8. The battery pack (1) according to claim 7, characterized in that: The at least one battery module (3) comprises at least one lithium-ion battery cell.

9. A motor vehicle having a battery pack (1) according to claim 7 or 8, which is designed to supply power and / or drive the motor vehicle.

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