Battery Housing

Abstract

The invention relates to a battery housing (1) comprising a first housing part (2) and a second housing part (3) connected to one another by a number of screws (5), the second housing part (3) having through holes for the screws (5) and the other housing part (2) having a thread. The battery housing according to the invention is characterized in that the thread is formed in the form of a threaded bush (7) which is connected to the one housing part (2) by means of a screwing or form-locking and has a thread (9) for receiving the screws (5), the threaded bush (7) being at least partially made of a material (10) which melts, softens or decomposes in the event of a thermal event.

Description

[Technical field]

[0001] The present invention relates to a battery housing of the type as precisely defined in the preamble of claim 1, comprising a housing lower part and a housing cover. [Background technology]

[0002] Battery housings for traction batteries which provide electric drive power for at least partially electrically driven vehicles are basically known from the prior art. To allow maintenance of the battery inside the battery housing, these battery housings usually consist of at least two housing parts which are threadedly connected to one another, for which one housing part is provided with a through-hole and the other housing part is provided with a thread, for example for appropriately screwing a housing cover to a housing lower part or to a component which is indirectly connected to the housing lower part.

[0003] In such housings, safety for the battery always plays an important role. In the event of a so-called thermal event, for example, where one or more single battery cells in the battery housing overheat and, as a result, hot gases and / or combustible particles are ejected, it must be possible to release the overpressure in the battery housing, for example by means of a rupture disk or a relief valve. In this connection, purely by way of example, reference can be made to US Pat. No. 5,399,433, which shows a diaphragm for venting the battery housing together with a relief valve. Generally, the hot gases that occur are appropriately directed via this relief valve to areas where only minor damage can occur. This entire process in a thermal event, also called thermal runaway, is generally referred to by the term venting to expel the gases.

[0004] In the case of screwed battery housings, the problem can arise that the screw connections of the housing parts loosen in such a thermal event, with the result that gas is released uncontrollably into the surroundings. This applies in particular to the screw connections which screw the battery cover to the corresponding elements inside the battery housing, for example in order to stabilize the battery cover over its entire surface. In the event of extreme overpressure, the screw connections can be destroyed, with the result that leakage occurs in the area of ​​the through-holes, even if sealing screws are generally used. If gas, in particular flammable gas, escapes here, in the worst case scenario, the corresponding through-holes will burst further or open further under the influence of heat, whereby even more gas will reach the surroundings in an uncontrolled manner. This must be avoided. Further, for another prior art reference can be made to US Pat. No. 5,399,633, which shows a two-part thermoplastic threaded bushing that can be used for any threaded connection. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] DE102019100094A1 [Patent Document 2] DE102007060081B4 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to provide a battery housing according to the preamble of claim 1 which ensures increased safety and prevents the above-mentioned disadvantages, in particular with regard to potential leakage in the area of ​​the screw connections. [Means for solving the problem]

[0007] According to the invention, this problem is solved by a battery housing having the features of claim 1, and here in particular the features recited in the characterizing part of claim 1. Advantageous embodiments and developments emerge from the dependent claims which rely thereon.

[0008] The battery housing according to the invention comprises two housing parts which are connected to each other by a number of screws. These housing parts can be, for example, a housing lower part and a housing cover which is screwed onto it. One housing part, in particular the housing lower part in the above-mentioned embodiment, has threads for receiving screws which protrude from the through-holes of the other housing part, i.e. in this case in particular the housing cover. According to the invention, these threads are configured in the form of threaded bushes. These threaded bushes are connected to the one housing part by means of a screw or a form-lock and have threads for receiving the screws. The threaded bushes are then at least partially made of a material which melts or decomposes in the event of a thermal event occurring in the spatial vicinity. That is to say, the material of the threaded bushes can be configured so that in the event of a thermal event occurring in the spatial vicinity of the threaded connection, this threaded connection breaks consistently or at least partially. In this way, a target breaking point is created, so that the threaded connection is separated from its threads, but the through-holes and the threaded connection are not affected. This allows the situation to be created where the cover as a whole comes off the other housing part, especially in the central area, but the through-openings remain closed, since the screw connections do not move any further, so that the battery housing as a whole remains hermetically sealed. The housing cover, as one housing part, which loses some of its central screw fastenings and may even bulge, then also serves to relieve the pressure increase in the battery housing due to the resulting increase in the internal volume of the battery housing, so that the corresponding safety elements, such as rupture disks, have enough time to react in order to properly direct the gases to the exhaust channel.

[0009] In this case, the threaded bush itself can preferably be formed from two materials, and according to a very advantageous development of the battery housing according to the invention, the threaded bush has a metallic material and a thermoplastic material. This combination of metal and thermoplastic, for example a thermoplastic polymer, allows for simple and efficient production, for example by loading the inner part of the metallic threaded bush into an injection molding machine and overmolding it accordingly with the other parts of the threaded bush. In the event of a thermal event, the thermoplastic material decomposes or melts accordingly, or at least softens to such an extent that this part of the threaded bush can no longer withstand the forces and the threaded connection breaks in the desired manner as a target breaking point.

[0010] Now, according to a very advantageous development of the battery housing according to the invention, the metallic material can provide the thread for the screw and the thermoplastic material can provide the connection to the other housing part. This construction is particularly efficient. The screw can engage into the metallic part of the threaded bush, so that the screw and possibly the seal between the threaded bush and the screw or the seal between the screw head and the housing part remain in place. That is to say, the relative position of the screw to the metallic part of the threaded bush does not change even if the target breaking point reacts, so that the through-hole of the housing part remains reliably blocked by the screw. Since the thermoplastic material cannot absorb as many forces as the metallic material and cannot withstand high temperatures, the connection to the other housing part via the thermoplastic material breaks above a certain temperature and / or a certain pressure. The target breaking point can thus be moved directly to the joining area with the second housing part, so that the break occurs exactly in the desired area.

[0011] In this case, the connection between the threaded bush and the second housing part can be made by a positive lock, so that the threaded bush is integrated into the so-called housing part and held therein by a bead of thermoplastic material or the like which passes between the two elements with a corresponding positive lock, which is sufficient to transmit the forces occurring in normal operation and to cause a corresponding desired break as a target break point in the event of a thermal event.

[0012] Alternatively, according to a further embodiment of the battery housing according to the invention, the connection can also be configured as a thread, which has the advantage that the threaded bush can be manufactured independently of the lower or second part of the battery housing, so that the threaded bush can be screwed into the thread of this second housing part and then the other housing part can be placed and screwed onto the threaded bush and thus indirectly onto the other housing part by means of screws.

[0013] In this case, according to a very advantageous development of the battery housing according to the invention, the screw itself can be configured as a sealing screw for the housing part with the through-hole, as already mentioned above. As a supplement to this, or in principle as an alternative, in the battery housing according to the invention, a seal can also be provided between the screw and the threaded bush, which seal is made of a heat-resistant material and therefore can maintain its functionality even in the event of a thermal event and is not melted or decomposed.

[0014] A further highly preferred embodiment of the battery housing according to the invention can be provided in such a way that a flange of the threaded bush is formed on the side facing the through hole. If the seal described on the basis of the previous embodiment is present, this seal can be accommodated between the housing part and this flange and reliably seals the structure. Furthermore, if the threaded bush is formed in such a way that its metallic material is provided with a thread for the screw, this part also includes the flange accordingly, so that such a seal is reliably held between the housing part and the threaded bush even in the event of reaction of the target breaking point, and thus reliably seals the through hole even in the event of reaction of the target breaking point.

[0015] In this case, the housing part with the through hole can preferably, but not necessarily, be a housing cover, and the housing part with the thread can be formed as a housing lower part, which has this thread, for example, on the outer periphery of a flange or in the center of a corresponding tension anchor against the surface of the thread lower part, and the tension anchor protrudes through a battery module in the battery housing or is at least indirectly held by such a battery module.

[0016] Further advantageous embodiments of the battery housing according to the invention are evident from the exemplary embodiment which is described in detail below with reference to the drawings. [Brief description of the drawings]

[0017] [Figure 1] 13A-13C are views of threaded connections between housing parts of a battery housing in an embodiment according to the invention. [Diagram 2] FIG. 2 shows a view of the screw connection according to FIG. 1 after a thermal event has occurred. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 1 shows a relevant cross-section of a battery housing 1 in a possible embodiment according to the invention, with a first housing part 2 configured as a housing lower part and a second housing part 3 realized here as a housing cover 3. The housing cover 3 has a through-hole 4 for a screw 5 for screwing the housing cover 3 to the housing lower part 2. The screw 5 is configured as a so-called sealing screw, which ensures the tightness of the through-hole 4 between the screw head and the housing cover 3 by means of a peripheral seal 6.

[0019] The thread for fastening the screw 5 in the housing lower part 2 is designed in the form of a threaded bush 7, which in the embodiment shown here consists of an inner part 8 made of metallic material with a through-drilled hole and a thread, here indicated with 9, for receiving the screw 5 or the thread of the screw 5.

[0020] The threaded bush 7 furthermore comprises an outer part, designated 10, which is manufactured from a thermoplastic resin, for example by overmolding the inner part 8 of the threaded bush 7 with the thermoplastic resin. The adhesion of the thermoplastic resin to the inner part 8 can here be purely by adhesion or gluing. However, form-locking connecting elements, not shown here, could also be provided. The outer circumference of the thermoplastic outer part 10 is formed with a thread 11, which is appropriately screwed into the thread of the second housing part 2. This construction ensures a good seal and at the same time a sufficient fastening of the housing cover 3 to the housing lower part 2.

[0021] In order to further improve the sealing of the through hole 4, a seal 12 can also be provided to seal this area, preferably sandwiched between the housing cover 3 and a flange 13 of the threaded bush 7, which flange 13 is preferably formed as part of the inner part 8 of the threaded bush 7 and therefore from a metal material.

[0022] If a thermal event occurs in the battery housing 1 around the described threaded connection, the battery housing 1 will experience an increase in pressure on the one hand and an increase in temperature on the other hand. After a certain time or after a certain limit pressure, the overpressure and harmful, possibly combustible gases are appropriately vented to a selected area around, typically by opening a rupture disk or the like. In order to prevent an undesirable escape of gases, in particular via the through-hole 4 in the battery cover 3, the described structure of the threaded bush 7 is provided. The thermoplastic material 10 of the threaded bush 7 is a so-called target break point in the event of an overpressure, which occurs in particular in combination with a high temperature due to a thermal event. The thermoplastic material 10 melts or decomposes or softens. The melted or softened material then can no longer withstand the pressure between the battery lower part 2 and the battery cover 3, and an outer area of ​​the threaded bush 7 breaks off, and the threaded bush 7 comes off the housing lower part 2. In FIG. 2, the structure shown in FIG. 1 is illustrated in the event of such a break of the thermoplastic material 10 of the threaded bush 7. This causes the battery cover 3 to rise slightly, thereby increasing the internal volume of the battery housing 1 and making it possible to relieve the pressure build-up. However, in particular in the event of such a thermal event and / or overpressure, a suitable break in the area of ​​the threaded bush 7 ensures that the screw 5 is located above the cover 3 and therefore that the through hole 4 also remains reliably sealed, so that no gas can escape here.

[0023] The seal 12 remains sandwiched between the flange 13 of the heat-resistant inner part 8 of the threaded bush 7 and the housing cover 3, the screw 5 remains in place, and the seal 6 in addition to the seal 12 reliably seals the through hole 4. However, the entire housing cover 3 is lifted from the housing bottom due to the breakage of the thermoplastic material 10 of the threaded bush 7. If these threaded connections are used, for example, with a cover plate, the latter will rise up and the effect already mentioned above is achieved. In all cases, such a type of threaded connection with the special threaded bush 7 therefore makes it possible to prevent the escape of undesirable gases and possibly flames through the through hole 4 of the threaded connection.

[0024] The reference numbers given to the components in Fig. 2 are the same as those given to the identical components in Fig. 1. The ascent of the structure consisting of the cover 3, the inner part 8, the threaded bush 7 and the screw 5 relative to the housing lower part 2 is correspondingly indicated by an arrow. The thermoplastic material 10 of the threaded bush 7 is still partly adhered to the inner part 8 of the threaded bush and still partly remains in the region of the thread 11. For the sake of clarity, this thermoplastic material is here referenced 10 in both positions.

Claims

1. A battery housing (1) comprising a first housing part (2) and a second housing part (3) connected to each other by a plurality of screws (5), the second housing part (3) having through holes for the screws (5) and the other housing part (2) having a screw thread, The battery housing (1), wherein the thread is configured in the form of a threaded bush (7) which is connected to one of the housing parts (2) by screwing or a form-locking and has a thread (9) for accommodating the screw (5), the threaded bush (7) being at least partially made of a material (10) which melts, softens or decomposes in the event of a thermal event.

2. 2. Battery housing (1) according to claim 1, characterized in that the threaded bush (7) comprises a metallic material (9) and a thermoplastic material (10) in a concentric arrangement.

3. 3. A battery housing (1) according to claim 2, characterized in that the metallic material comprises the threads (9) for the screws (5) and the thermoplastic material forms the connection to the housing part (2).

4. 4. The battery housing (1) according to claim 3, characterized in that the connection is designed as a form-locking connection.

5. 4. The battery housing (1) according to claim 3, characterized in that the connection is configured as a screw thread (11).

6. 6. The battery housing (1) according to claim 1, wherein the screw (5) is configured as a sealing screw (5) for the housing part (3) having the through hole (4).

7. 6. The battery housing (1) according to claim 1, wherein a seal (12) made of a heat-resistant material is arranged between the threaded bush (7) and the housing part (3) having the through hole (4) so ​​as to surround the through hole (4).

8. The battery housing (1) according to any one of claims 1 to 5, characterized in that the threaded bush (7) has a flange (13) on the side facing the housing part (3) having the through hole (4).

9. 6. The battery housing (1) according to claim 1, wherein the housing part (3) having the through hole (4) is configured as a housing cover (3).

10. 6. A battery housing (1) according to any one of the preceding claims, characterized in that the housing part (2) with the screw thread (11) forms a lower housing part (2).

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