Method for manufacturing a traction battery for a motor vehicle and corresponding manufacturing equipment

Abstract

Method for manufacturing a traction battery (2) of a motor vehicle, characterized in that a battery housing (3) of the traction battery (2) is filled with a thermal conductivity comprising at least a first component and a second component, wherein the thermal conductivity is conveyed from a storage container (6) through a fluid line (5) towards a filling device (4) used for filling the battery housing (3), and wherein upstream of the filling device (4) a homogeneity of the thermal conductivity is determined by means of a sensor (8) and if the homogeneity deviates from a target value, the thermal conductivity is supplied to a homogenization device (9), homogenized in this device and subsequently supplied to the filling device (4).

Description

[0001] The invention relates to a method for manufacturing a traction battery for a motor vehicle and to a corresponding manufacturing device.

[0002] For example, German patent application DE 10 2017 128 529 A1 is known from the prior art. This document describes a motor vehicle battery, specifically a traction battery for a motor vehicle, with a battery housing that has an interior compartment partially bounded by a housing frame and a housing base, with several battery modules arranged in the interior compartment, and with at least one first cooling channel formed in the area of ​​the housing base for cooling the battery modules from a first side. The interior compartment is bounded opposite the housing base by a housing top or a housing cover, wherein at least one second cooling channel is formed in the area of ​​the housing top or housing cover for cooling the battery modules from a second side.

[0003] Furthermore, German patent application DE 103 20 186 A1 discloses a thermal paste for the thermal coupling of a power semiconductor device to a heat sink. The thermal paste consists of a base material and at least one filler. The individual components have the following properties: a dynamic viscosity of the base material between 25 and 500 mPa·s, at least one filler consists of metal particles, the filler(s) have a particle size of less than 20 µm, and the thermal paste has a filler content of between 20 and 70%.

[0004] This results in a thermal paste with a specific resistance of less than 100 Ωm and a thermal resistance of 3.4 W / (K·m).

[0005] Document DE 102018 010 115 A1 discloses a method for manufacturing a battery comprising several battery cells for a motor vehicle, in which a thermal paste is applied to the battery cells, via which the battery cells are at least thermally coupled to a cooler for cooling the battery cells, wherein the respective height of the respective battery cell is detected during the application of the thermal paste, and wherein the thermal paste is applied to the respective battery cell depending on the respective detected height.

[0006] The prior art also includes the publication DE 10 2017 116 420 A1.

[0007] The object of the invention is to propose a method for manufacturing a traction battery for a motor vehicle which has advantages over known methods, in particular ensuring good heat conduction between at least one battery cell of the traction battery and a battery housing.

[0008] According to the invention, this is achieved by a method for manufacturing a traction battery with the features of claim 1. It is provided that a battery housing of the traction battery is filled with a thermal conductivity comprising at least one first component and a second component, wherein the thermal conductivity is conveyed from a storage container through a fluid line towards a filling device used for filling the battery housing, and wherein upstream of the filling device, the homogeneity of the thermal conductivity is determined by means of a sensor, and if the homogeneity deviates from a target value, the thermal conductivity is fed to a homogenization device, homogenized therein, and subsequently fed to the filling device.

[0009] The process serves to manufacture the traction battery for a motor vehicle, in particular using the corresponding manufacturing equipment. The traction battery is designed and intended to provide electrical energy to the motor vehicle. The traction battery can be an integral part of the motor vehicle or exist separately. The only important factor is that it serves, or can serve, as a traction battery for the motor vehicle. Within the motor vehicle, the traction battery serves to operate a drive system or drive unit of the motor vehicle, which in turn serves to provide drive torque for propelling the motor vehicle. After the traction battery is mounted on or in the motor vehicle, it is electrically connected to the drive system.

[0010] The traction battery has a battery housing that serves to accommodate at least one cell module of the traction battery. The cell module comprises at least one battery cell, but preferably several electrically interconnected battery cells. Particularly preferably, several such cell modules are arranged in the battery housing after the traction battery has been manufactured.

[0011] During operation of the traction battery, for example during rapid charging or discharging, heat is generated in the cell modules, which must be dissipated to ensure high performance of the traction battery. For this purpose, the battery housing preferably has a cooling device that operates either passively or – preferably – actively. In the former case, a heat sink can be arranged on the battery housing, or the battery housing itself can be designed as a heat sink, at least in part. In the latter case, a coolant line is located on or in the battery housing, through which coolant flows, at least temporarily, during operation of the traction battery.

[0012] In any case, it must be ensured that the heat from the cell module(s) is reliably transferred to the battery housing. For this purpose, the battery housing is at least partially filled with thermal conductivity during the manufacturing of the traction battery. The thermal conductivity is arranged in such a way that, after the cell module is positioned in the battery housing, the thermal conductivity is in contact with both the cell module and the battery housing.

[0013] A multi-component thermal conductivity is used, consisting of at least a first component and a second component. The first component is, for example, a carrier material, and the second component is a filler, with the thermal conductivity of the thermal conductivity being primarily achieved by the filler. Preferably, the filler has a higher thermal conductivity than the carrier material. The thermal conductivity is in the form of a liquid or a paste. The latter is understood to be a solid-liquid mixture, where, for example, the first component is a liquid and the second component is a solid. For example, the second component contains or consists of metal particles. Particularly preferably, the proportion of the second component in the thermal conductivity is at least 50%, at least 60%, at least 70%, or at least 80%.This results in particularly good heat conduction using the thermal conductivity medium.

[0014] The thermal conductivity is processed by being conveyed through the fluid line towards the filling device. The filling device is designed and configured to introduce the thermal conductivity into the battery housing. Therefore, the thermal conductivity exits the fluid line during the filling process. The thermal conductivity is supplied in a reservoir. This reservoir is connected to the fluid line in a fluid-flow-compatible manner. For example, the reservoir contains a quantity of thermal conductivity sufficient for the production of several traction batteries. Preferably, the reservoir is in the form of a drum. In this case, the fluid line is inserted into the drum, for example, through a bung hole, to access the thermal conductivity.

[0015] The storage container contains both the first and second components in a state that is at least partially mixed. Ideally, the components are filled into the storage container in a completely and homogeneously mixed state. The storage container is then connected to the fluid line, and the thermal conductivity is drawn from it and conveyed towards the filling device. However, due to storage and / or transport times, the components of the thermal conductivity can separate within the storage container, resulting in the thermal conductivity no longer being in a completely homogeneous form. For example, the first and second components may separate, with the typically heavier filler settling at the bottom and the typically lighter carrier material rising to the top.

[0016] This can lead to variations in the density, viscosity, and / or thermal conductivity of the thermal interface material within the container. If the thermal interface material is introduced into the battery housing in this state, the thermal conductivity will differ locally between the cell module(s) and the battery housing. This can result in varying temperature loads, potentially reducing the lifespan of the traction battery.

[0017] For this reason, such fluctuations in the homogeneity of the thermal conductivity should be prevented or at least reduced. To this end, a sensor is positioned between the storage container and the filling device to measure the homogeneity of the thermal conductivity at this point. In other words, the sensor serves to determine the homogeneity of the thermal conductivity between the storage container and the filling device. If the measured homogeneity deviates from the target value, the thermal conductivity is not initially fed to the filling device, but rather to the homogenization unit. Here, the thermal conductivity is homogenized to ensure uniform thermal conductivity. After homogenization, the homogenized thermal conductivity is fed to the filling device and used to fill the battery housing.

[0018] The sensor is therefore used in particular to detect the rheological state of the thermal conductivity. The sensor is preferably arranged such that it is in direct contact with the thermal conductivity, in particular that the thermal conductivity flows over and / or onto it. It can be provided that the thermal conductivity is only fed to the homogenization device for homogenization if the measured homogeneity deviates downwards from the target value, i.e., is lower than it. The target value is accordingly defined as a homogeneity threshold, below which the measured homogeneity triggers the homogenization of the thermal conductivity.

[0019] The described procedure ensures that the thermal interface material introduced into the battery housing always exhibits a sufficiently high degree of homogeneity to guarantee uniform thermal conductivity and, consequently, a uniform temperature distribution within the battery housing. This results in consistently good cooling of the cell modules and, therefore, a long service life for the traction battery.

[0020] A further development of the invention provides that a density sensor, in particular a capacitive sensor or an ultrasonic sensor, is used as the sensor. The use of the density sensor enables a particularly simple and reliable determination of homogeneity, especially when the first and second components have different densities. Preferably, the density of the second component deviates significantly from the density of the first component; for example, the density of the second component is greater than the density of the first component by a factor of at least 1.5, at least 2.0, or at least 2.5.

[0021] The density sensor measures the density of the thermal interface material. For example, the homogeneity can be determined from this density and subsequently compared to the target value. Alternatively, the density can be directly compared to the target value, where the target value corresponds to the density of the fully homogenized thermal interface material. The density sensor can be, for example, a capacitive or ultrasonic sensor. In any case, using the density sensor ensures a simple and reliable determination of the density and corresponding homogeneity.

[0022] A further development of the invention provides that a homogenizing device is used that is arranged in a bypass line running parallel to the fluid line in terms of flow direction and / or is fluidically connected to the fluid line via the bypass line. As already explained, the homogenizing device serves to homogenize the thermal conductivity. The thermal conductivity is supplied from the fluid line to the homogenizing device for homogenization, at least temporarily, namely via the bypass line. Accordingly, the homogenizing device is fluidically connected to the fluid line via the bypass line.

[0023] For example, it is possible for the bypass line to branch off from the fluid line at exactly one point and lead to the homogenizing unit. However, it is also possible for the bypass line to run parallel to the fluid line in terms of flow direction, branching off from it at a first point and then rejoining the fluid line at a second point downstream of the first branch. In this case, the bypass line passes over the homogenizing unit.

[0024] In the first case, for example, the thermal conductivity is taken from the fluid line at the first branch and fed to the homogenizing unit. The thermal conductivity is then homogenized in the homogenizing unit and subsequently returned to the fluid line via the bypass line, specifically at the first branch. If both a first and a second branch are present, continuous homogenization can be performed using the homogenizing unit. For this, the thermal conductivity is taken from the fluid line at the first branch and fed to the homogenizing unit via the bypass line for homogenization. After homogenization, the thermal conductivity is returned to the fluid line via the bypass line, specifically at the second branch.This ensures the continuous operation of the manufacturing facility.

[0025] Alternatively, the second branch can, of course, be positioned upstream of the first, particularly upstream of the sensor. This configuration enables particularly reliable operation of the production equipment because the homogenized thermal interface material is again checked for homogeneity deviations using the sensor. Naturally, it is also possible to feed the thermal interface material via the bypass line not back into the fluid line, but rather into the storage container. In this case as well, the homogeneity of the thermal interface material is checked again using the sensor. In any case, the described procedure, combined with a simple design, allows for reliable homogenization of the thermal interface material, should this be necessary.

[0026] The homogenizing device is in no way intended to induce a chemical reaction between the components of the thermal interface material, but solely for homogenization. After homogenization, the components exist in the same chemical form as before homogenization, i.e., in a chemically unchanged form. In particular, the components are chemically separated from each other both before and after homogenization.

[0027] A further development of the invention provides that the homogenization device homogenizes the thermal conductivity medium by means of a static mixer, an agitator, and / or a mixing vessel. The homogenization device thus comprises the static mixer, the agitator, or the mixing vessel. The static mixer is characterized in that the homogenization of the thermal conductivity medium occurs due to the flow motion of the thermal conductivity medium itself. The static mixer therefore has no moving elements. The static mixer is, for example, integrated into the bypass line and is particularly suitable if the bypass line is fluidically connected to the fluid line via both the first branch and the branch. The agitator is understood to be a device for stirring the thermal conductivity medium. The stirring is carried out in such a way that the components of the thermal conductivity medium are mixed.

[0028] Alternatively or additionally to the static mixer and / or the agitator, the homogenization device can include a mixing vessel. The mixing vessel serves to hold a specific quantity of the thermal interface material, which is subsequently homogenized within it, for example, using a mixer. The mixing vessel can be used both when the bypass line is connected to the fluid line via a single branch and when the bypass line is connected to the fluid line via multiple branches. In any case, the described procedure ensures reliable homogenization of the thermal interface material.

[0029] A further development of the invention provides that a specific quantity of the thermal conductivity is first introduced into the mixing container, then homogenization is carried out, and subsequently the thermal conductivity is removed from the mixing container and fed to the filling device. The mixing container is therefore not specifically designed for continuous homogenization. Rather, the specific quantity of thermal conductivity is first added to it.

[0030] Only then is the thermal conductivity fluid present in the mixing vessel homogenized. The homogenized thermal conductivity fluid is then removed from the mixing vessel and fed to the filling device, for example via the bypass line and / or the fluid line. However, it is also possible to feed the thermal conductivity fluid directly from the mixing vessel to the filling device, particularly bypassing the fluid line and / or the bypass line.

[0031] Preferably, the quantity of thermal conductivity introduced into the mixing vessel corresponds to at least 25%, at least 50%, or at least 75% of the quantity of thermal conductivity present in the storage container. Alternatively, the entire quantity of thermal conductivity present in the storage container may be added to the mixing vessel before homogenization. This results in a particularly high degree of homogeneity of the thermal conductivity.

[0032] A further development of the invention provides that the fluid line is connected to the storage container on one side and to the filling device on the other, wherein the sensor is positioned at a distance from the storage container, relative to the flow distance between the storage container and the filling device, of at most 0.25, at most 0.2, at most 0.15, or at most 0.1. In other words, the sensor is arranged as close as possible to the storage container and as far away as possible from the filling device in order to achieve sufficient homogenization of the thermal conductivity along the remaining flow path from the sensor to the filling device. This distance ensures that the thermal conductivity is sufficiently homogenized before it is supplied to the filling device.

[0033] A further development of the invention provides that, if the homogeneity deviates from the setpoint, a switching valve is actuated to supply the heat transfer fluid to the homogenization device. The switching valve is, for example, fluidically connected to or located within the fluid line. Preferably, the switching valve is in the form of a 3 / 2-way valve, which is arranged in the fluid line and additionally connected to the bypass line. In a first switching position of the switching valve, the bypass line is fluidically separated from the fluid line, whereas in a second switching position of the switching valve, a flow connection exists between the fluid line and the bypass line. The use of the switching valve makes it possible, in particular, to perform homogenization only temporarily, namely only when the sensor has measured a deviation in the homogeneity of the heat transfer fluid from the setpoint.This reduces the energy required to operate the manufacturing facility.

[0034] A further development of the invention provides that the thermal conductivity medium is conveyed, at least temporarily, towards the filling device by means of a conveying device, with the sensor downstream of the conveying device determining the homogeneity of the thermal conductivity medium. The conveying device serves to pump the thermal conductivity medium from the storage container through the fluid line towards the filling device. The sensor for measuring the homogeneity of the thermal conductivity medium is now arranged downstream of the conveying device. This has the advantage that a certain degree of homogenization of the thermal conductivity medium has already occurred in the conveying device before it reaches the sensor.

[0035] A further development of the invention provides that a mixture of a carrier material and a filler is used as the thermal conductor, wherein the carrier material has a lower viscosity and / or density than the filler. It has already been mentioned above that the carrier material and the filler together form a paste, wherein the carrier material is, for example, made of plastic and / or the filler is made of metal. Additionally or alternatively, it can be provided that the density of the carrier material is lower than the density of the filler. This enables particularly good thermal conductivity of the thermal conductor.

[0036] The invention further relates to a manufacturing device for producing a traction battery for a motor vehicle, in particular for carrying out the method as described in this description. The manufacturing device is designed and configured to fill a battery housing of the traction battery with a thermal conductivity comprising at least one first component and a second component. The thermal conductivity is conveyed from a storage container through a fluid line towards a filling device used for filling the battery housing. Upstream of the filling device, a sensor determines the homogeneity of the thermal conductivity. If the homogeneity deviates from a target value, the thermal conductivity is fed to a homogenization device, homogenized therein, and subsequently fed to the filling device.

[0037] The advantages of such a design of the manufacturing facility and such a procedure have already been discussed. Both the manufacturing facility and the method for operating it may be further developed as described in this document, and reference is made to that description in this regard.

[0038] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The only embodiment shown is... Figure shows a schematic representation of a manufacturing facility for producing a traction battery for a motor vehicle.

[0039] The figure shows a schematic representation of a manufacturing device 1 used to produce a traction battery 2 for a motor vehicle, which is only indicated here. According to the embodiment shown, the manufacturing device 1 is designed and configured for the simultaneous production of several traction batteries 2. Each traction battery 2 has a battery housing 3 into which a thermal interface material can be filled by means of a filling device 4. The filling device 4 is fluidically connected to a reservoir 6 via a fluid line 5. The thermal interface material is provided in the reservoir 6. In the following, only one of the traction batteries 2, one of the battery housings 3, and one of the filling devices 4 will be discussed. However, the corresponding descriptions are always applicable to all of the elements mentioned.

[0040] With the aid of a conveying device 7, which is designed in particular as a pump, the thermal conductivity is extracted from the storage container 6 and conveyed, at least temporarily, towards the filling device 4. Downstream of the conveying device 7, a sensor 8 is arranged in the fluid line 5, by means of which the homogeneity of the thermal conductivity is determined. If the determined homogeneity deviates from a target value, the thermal conductivity is supplied to a homogenizing device 9, preferably via a bypass line 10. The bypass line 10 branches off from the fluid line 5 at a first branch 11 and rejoins it at a second branch 12. The second branch 12 is arranged in the fluid line 5 downstream of the first branch 11.

[0041] In the embodiment shown here, a switching valve 13 is located at the first branch 11, by means of which the bypass line 10 can be connected to the fluid line 5. For example, the switching valve 13 is designed such that in a first switching position it opens a flow connection through the fluid line 5 and fluidically separates the bypass line 10 from the fluid line 5. In a second switching position, however, the flow connection through the fluid line 5 is interrupted and the bypass line 10 is fluidically connected to the fluid line 5. In the first switching position, the heat transfer fluid flows continuously through the fluid line 5 towards the filling device, whereas in the second switching position the heat transfer fluid flows only through a portion of the fluid line 5 and otherwise through the bypass line 10, which runs parallel to the fluid line 5.

[0042] When the thermal conductivity flows through the homogenization device 9, particularly when the switching valve 13 is in its second position, it is homogenized and subsequently fed back into the fluid line 5 and, accordingly, into the filling device 4. This ensures particularly thorough mixing of the thermal conductivity. REFERENCE MARK LIST: 1 Manufacturing facility 2 traction batteries 3 battery cases 4 Filling device 5 Fluid line 6 storage containers 7 Funding facility 8 Sensor 9 Homogenization unit 10 Bypass lines 11 1st branch 12 2nd branch 13 Switching valve

Claims

[1] Method for producing a traction battery (2) of a motor vehicle, characterized by in that a battery housing (3) of the traction battery (2) is filled with a heat-conducting agent having at least a first component and a second component, wherein the heat-conducting agent is conveyed from a storage container (6) through a fluid line (5) in the direction of a filling device (4) used to fill the battery housing (3), and wherein upstream of the filling device (4) a homogeneity of the heat-conducting agent is determined by means of a sensor (8), and in the event of a deviation of the homogeneity from a target value, the heat-conducting agent is fed to a homogenization device (9), homogenized therein and subsequently fed to the filling device (4). [2] Method according to claim 1, characterized by that a density sensor, a capacitive sensor or an ultrasonic sensor is used as the sensor (8). [3] Method according to one of the preceding claims, characterized by that a homogenization device (9) arranged in a bypass line (10) running fluidically parallel to the fluid line (5) and / or fluidically connected to the fluid line (5) via the bypass line (10) is used as the homogenization device (9). [4] Method according to one of the preceding claims, characterized by that the homogenization device (9) homogenizes the heat-conducting agent by means of a static mixer, an agitator and / or a mixing container. [5] Method according to the preceding claim, characterized by that a certain amount of the heat conducting agent is first introduced into the mixing container, then homogenization is carried out and subsequently the heat conducting agent is removed from the mixing container and fed to the filling device (4). [6] Method according to one of the preceding claims, characterized by that the fluid line (5) is connected on the one hand to the storage container (6) and on the other hand to the filling device (4), wherein the sensor (8) has a fluidic distance from the storage container (6) which, in relation to a fluidic distance between the storage container (6) and the filling device (4), is at most 0.25, at most 0.2, at most 0.15 or at most 0.

1. [7] Method according to one of the preceding claims, characterized by that when the homogeneity deviates from the target value, a switching valve (13) is actuated to supply the heat-conducting agent to the homogenization device (9). [8] Method according to one of the preceding claims, characterized by that the heat-conducting agent is conveyed at least temporarily by means of a conveying device (7) in the direction of the filling device (4), wherein the sensor (8) downstream of the conveying device (7) determines the homogeneity of the heat-conducting agent. [9] Method according to one of the preceding claims, characterized by that a mixture of a carrier material and a filler is used as the thermal conductivity agent, wherein the carrier material has a lower viscosity and / or density than the filler. [10] Manufacturing device (1) for producing a traction battery (2) of a motor vehicle, in particular for carrying out the method according to one or more of the preceding claims, characterized byin that the production device (1) is provided and designed to fill a battery housing (3) of the traction battery (2) with a heat-conducting agent having at least a first component and a second component, wherein the heat-conducting agent is conveyed from a storage container (6) through a fluid line (5) in the direction of a filling device (4) used to fill the battery housing (3), and wherein upstream of the filling device (4) a homogeneity of the heat-conducting agent is determined by means of a sensor (8), and in the event of a deviation of the homogeneity from a target value, the heat-conducting agent is fed to a homogenization device (9), homogenized therein and subsequently fed to the filling device (4).

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