DE102021108516A1 - PROCESS FOR FILLING A BATTERY CASE WITH A FLUID AND MANUFACTURING PLANT FOR MANUFACTURING A BATTERY - Google Patents

Abstract

The invention relates to a method for filling a battery housing (106) of a battery (102) with a fluid (116). The method includes: determining a volume (VG) of the battery case (106) in a pressure measurement method; determining an amount of fluid with which the battery case (106) is to be filled from the volume (VG) of the battery case (106); and generating a control signal (112) for controlling a filling device (114) for filling the battery housing (106) with the fluid (116) based on the amount of fluid.

Description

technical field

The present invention relates to a method for filling a battery housing of a battery with a fluid. Furthermore, the invention relates to a production plant, a computer program and a computer program product for carrying out the method mentioned.

State of the art

In the production of a drive battery, it is often necessary to fill a battery housing of the drive battery with a fluid, for example for cleaning purposes, for inerting, for electrical and/or thermal insulation and/or for cooling.

The filling process usually only takes place when the battery housing is already closed. In addition, the finished battery housing can have a more or less fissured geometry, which can vary from battery housing to battery housing within tolerances due to production. These circumstances can lead to inaccurate dosing in connection with a filling according to the specified filling level. Furthermore, the determination of the correct fill level can be relatively complex and error-prone, particularly in the case of large-area battery housings, due to housing and positional tolerances.

For example, in vehicle transmissions, it is common to evacuate the transmission case prior to filling with oil to avoid air pockets that could result in an erroneous level measurement. Filling is often done simply with the help of a dipstick or a viewing window.

Description of the invention

It is an object of the invention to improve the manufacture of a battery. In particular, the object of the invention is to improve the filling of a battery housing of a battery with a fluid.

This object is solved by the subject matter of the independent claims. Advantageous developments of the invention are specified in the dependent claims, the description and the accompanying figures. In particular, the independent claims of a claim category can also be developed analogously to the dependent claims of another claim category.

The approach described below is essentially based on the fact that an actual volume of a battery housing can be measured in a pressure measurement method and the battery housing can be filled with a fluid depending on this measured volume. In comparison to the filling by level measurement mentioned above, such a volumetric dosing is simpler, faster and more accurate. In particular, the fluid can thus be dosed individually for each battery case.

It is also advantageous that means which are generally available anyway can be used to carry out the method described here and below, for example to check the battery housing for leaks. The production costs for the battery can thus be reduced.

A first aspect of the invention relates to a method for filling a battery housing of a battery with a fluid. The method comprises at least the following steps: determining a volume of the battery housing in a pressure measurement method; determining an amount of fluid with which to fill the battery case from the volume of the battery case; and generating a control signal for controlling a filling device for filling the battery housing with the fluid based on the amount of fluid.

For example, the method can be performed automatically by a manufacturing facility for manufacturing the battery.

The battery can be, for example, a high-voltage battery with a nominal voltage of at least 120V, in particular at least 300V.

For example, the battery may be a traction battery for an electric vehicle such as an electric car, electric truck, electric bus, or electric two-wheeler. An electric vehicle can also be understood to mean a vehicle with a hybrid drive, for example in the form of a pure hybrid or a plug-in hybrid. However, other applications of the battery are also possible.

In particular, the battery can be designed as a lithium-ion accumulator, lithium-polymer accumulator or lithium-iron phosphate accumulator. A different cell chemistry of the battery is also conceivable.

A plurality of battery cells can be arranged in the battery housing. In addition, at least one other component of the battery can be arranged in the battery housing, for example have a sensor system for measuring a voltage, a current and/or a temperature of the battery cells and/or control electronics for influencing a voltage, a current and/or a temperature of the battery cells.

A battery cell can generally be understood as a galvanic cell for converting chemical and electrical energy. The battery cells can be designed, for example, as cylindrical cells, prismatic cells and/or as so-called pouch cells with a bag-like or pocket-like outer shell. The battery cells can be connected to one another in series and/or in parallel.

It is possible for the battery to be composed of a plurality of cell modules. In this case, each cell module can comprise a plurality of battery cells and, in addition, a cell module housing for accommodating the battery cells. In this case, a battery housing can also be understood to mean, for example, such a cell module housing. Alternatively, a battery housing can also be understood to mean a larger housing for accommodating a plurality of cell module housings. The cell modules can be connected to one another in series and/or in parallel.

The fluid can be a gas and/or a liquid. For example, the fluid can be an inert gas or an oil, such as a cooling oil. Such a cooling oil can be filled into the battery housing to cool the individual battery cells.

A quantity of fluid can be understood to mean a dosing volume of the fluid. For example, the amount of fluid can be determined according to a predetermined ratio of the volume of the battery case. It can also be that the amount of fluid is additionally or alternatively determined based on a defined residual air volume.

In short, the method described here and below can be used to determine the volume, for example online in the production process, using a gas pressure test. In this case, for example, a gas, z. B. air, from a gas container with a known reference volume at a known reference pressure in the battery case. Finally, the volume of the battery housing can be determined from the total pressure that occurs in combination with the known values of reference volume and reference pressure. In this way, inaccuracies, such as those that can occur when measuring the filling quantity using a level sensor due to housing or position tolerances, can be avoided.

The method described here and below can be carried out, for example, after a leak test of the battery housing. This avoids inaccuracies in determining the volume of the battery housing, for example as a result of a leak in the battery housing. It is also advantageous that the same measuring equipment can be used to check for leaks and to determine the volume of the battery housing. The manufacturing effort can thus be reduced.

A second aspect of the invention relates to a manufacturing system for manufacturing a battery. The manufacturing facility is configured to carry out the method according to an embodiment of the first aspect of the invention. For this purpose, the production system includes a measuring device for determining the volume of the battery housing in the pressure measurement method and a control device for determining the amount of fluid from the volume of the battery housing and for generating the control signal for controlling the filling device based on the amount of fluid.

The control signal can also be generated in a computing unit in which, for example, the volume is determined. The computing unit can be part of the control unit or separate from it.

The production facility can include a processor for executing a computer program, the execution of which causes the execution of the method, a memory for storing the computer program and/or data communication interfaces for data communication with peripheral devices. At least one of the components mentioned can be a hardware and/or software component of the measuring device, for example a computing unit of the measuring device, and/or the control device.

Features of the method according to an embodiment of the first aspect of the invention can also be features of the production plant and vice versa.

A third aspect of the invention relates to a computer program with instructions that cause the manufacturing system according to an embodiment of the second aspect of the invention to carry out the method according to an embodiment of the first aspect of the invention. The manufacturing facility may include at least one processor, the instructions ver cause to carry out the method according to an embodiment of the first aspect of the invention.

A fourth aspect of the invention relates to a computer-readable medium on which the computer program according to an embodiment of the third aspect of the invention is stored. The computer-readable medium can be volatile or non-volatile data storage. For example, the computer-readable medium can be a hard drive, USB storage device, RAM, ROM, EPROM, or flash memory. The computer-readable medium can also be a data communication network such as the Internet or a data cloud (cloud) enabling a download of a program code.

Features of the method according to an embodiment of the first aspect of the invention can also be features of the computer program and/or the computer-readable medium and vice versa.

Possible features and advantages of embodiments of the invention can be considered, among other things, and without limiting the invention, as being based on the ideas and insights described below.

According to one embodiment, the pressure measurement method comprises at least the following steps, which can preferably be carried out in the order given: introducing a gas from a gas container into the battery housing, the gas container having a reference volume and being filled with a reference pressure; measuring a resulting final pressure of the gas in the battery case and/or the gas container; Determining the volume of the battery case from the reference volume, the reference pressure and the resulting ultimate pressure.

The battery housing and the gas container fluidically connected to the battery housing can be viewed as a fluidic system. The resulting final pressure can be understood to mean a constant gas pressure in the fluidic system, which is established after a certain time when the gas is introduced from the gas container into the battery housing.

A reference pressure can be understood to mean a known initial pressure of the gas stored in the gas container before the gas is introduced into the battery housing. A reference volume can be understood to mean a known volume of the gas container and/or a known volume of the gas stored in the gas container.

The volume of the battery housing can be calculated, for example, using a mathematical function from the reference volume, the reference pressure and the resulting end pressure, as will be described in more detail below. Alternatively, the volume of the battery housing can also be determined by selecting a corresponding value from a lookup table.

For example, the battery housing can be closed in a fluid-tight manner, except for an opening for introducing the gas. The opening for introducing the gas can be specially designed for connecting the gas container, i. H. for measuring the volume of the battery case, may be provided on the battery case. However, it is also possible for the gas to be introduced and the fluid to be filled via one and the same opening in the battery housing.

This embodiment enables a dead volume of the battery housing to be determined precisely with relatively little measuring effort.

According to one embodiment, the volume of the battery case is determined with: $$V_G=\frac{p_{\text{ref}}\cdot V_{\text{ref}}}{p_{\text{total}}}-V_{\text{ref}}.$$

V _G stands for the volume of the battery housing, V _Ref for the reference volume, p _Ref for the reference pressure and p _Ges for the resulting final pressure of the entire system. In this way, the volume of the battery housing can be determined with relatively little computing effort. As mentioned above, the volume of the battery housing can also be taken from a lookup table, for example, as an alternative to the aforementioned calculation. Such a lookup table can be stored, for example, in a memory of the measuring device of the production plant.

According to one embodiment, the method further comprises: determining whether or not the amount of fluid is sufficient by comparing the amount of fluid to a minimum amount of fluid; if it has been determined that the amount of fluid is sufficient: generating the control signal based on the amount of fluid; and/or if it has been determined that the amount of fluid is insufficient, determining a corrected amount of fluid by correcting the amount of fluid and generating the control signal based on the corrected amount of fluid. For example, the amount of fluid can be corrected by a fixed or variable correction value to determine the corrected amount of fluid. The correction value can, for example, depend on the particular Be specified volume of the battery case and / or depending on a deviation of the particular volume of the battery case from a target volume of the battery case. It is possible, for example, that the control signal is not generated if the deviation from the target volume of the battery housing is outside a specified tolerance range. This embodiment can ensure that the battery housing is always filled with a sufficient amount of fluid, provided its volume is within the tolerance range.

That is, according to one embodiment, the method includes: determining whether the amount of fluid is sufficient or not by comparing the amount of fluid to a minimum amount of fluid. generating the control signal based on the determined amount of fluid if the amount of fluid is determined to be sufficient. determining a corrected amount of fluid by calculating a difference between the determined amount of fluid and the minimum amount of fluid when the amount of fluid is determined to be insufficient. The control signal can then be generated based on the corrected amount of fluid.

According to one embodiment, the battery housing is part of a high-voltage battery for supplying electrical energy to an electric drive motor of a vehicle, for example an electric, hybrid or plug-in hybrid vehicle. Such a high-voltage battery (see also above) can have a relatively large area. With this embodiment, a correspondingly large battery housing of the high-voltage battery can be filled easily and precisely.

According to one embodiment, the control signal is generated to fill the battery case with an oil as the fluid. The oil can be a cooling oil, for example. However, other heat transfer media for filling the battery housing are also conceivable. In this way, thermal and/or electrical decoupling can be achieved between battery components arranged in the battery housing.

According to one embodiment, the control signal is generated to fill the battery case with an inert gas as the fluid. As a result, reactive and potentially explosive gases can be displaced or sufficiently diluted from inside the battery housing.

According to one embodiment, the measuring device comprises a gas container for introducing a gas into the battery housing, the gas container having a reference volume and being filled with a reference pressure; a pressure sensor system for measuring a resulting final pressure of the gas in the battery housing and/or the gas container; a computing unit for determining the volume of the battery housing from the reference volume, the reference pressure and the resulting end pressure. The pressure measurement method can be carried out automatically by the computing unit, for example. The computing unit can include hardware and/or software components. The pressure sensor system can include one or more pressure sensors, which can be arranged in the gas container, the battery housing and/or a gas line fluidically connecting the gas container to the battery housing. It is possible for the measuring device to be configured to carry out a leak test of the battery housing in addition to determining the volume of the battery housing, for example using a differential pressure measurement method.

According to one specific embodiment, the production facility also includes a filling device for filling the battery housing with the fluid by processing the control signal. The filling device can include, for example, a fluid container, a fluid line connected to the fluid container, for example in the form of a hose or snout, and a dosing device for controlled delivery of the fluid from the fluid container via the fluid line into the battery housing. The metering device may be configured to process the control signal such that the amount of fluid determined by the controller is delivered into the battery housing. This enables accurate volumetric dosing of the fluid.

character list

• 1 eine schematische Darstellung einer Fertigungsanlage gemäß einem Ausführungsbeispiel der Erfindung;
• 2 ein Flussdiagramm eines Verfahrens gemäß einem Ausführungsbeispiel der Erfindung.

An advantageous exemplary embodiment of the invention is explained below with reference to the accompanying figures. Show it:

• 1 a schematic representation of a production plant according to an embodiment of the invention;
• 2 a flowchart of a method according to an embodiment of the invention.

The figures are only schematic representations and only serve to explain the invention. Elements that are the same or have the same effect are provided with the same reference symbols throughout.

Detailed description

1 shows schematically a manufacturing system 100 for manufacturing a battery 102. The Batte rie 102 comprises a plurality of electrically conductively connected battery cells 104 and a battery housing 106 in which the battery cells 104 are arranged.

The battery 102 can be a high-voltage battery, in particular a drive battery for an electric vehicle. The battery 102 can be designed as a lithium-ion accumulator, for example. The battery cells 104 can be designed as cylindrical, prismatic and/or pouch cells. However, other embodiments of battery 102 or battery cells 104 are also possible.

The manufacturing system 100 includes a measuring device 108 which is configured to determine a volume V _g of the battery housing 106 in a pressure measuring method. Furthermore, the production system 100 includes a control device 110 which is configured to generate a control signal 112 for controlling a filling device 114 of the production system 100 based on the volume V _g . Controlling the filling device 114 by means of the control signal 112 can cause the battery housing 106 to be filled with a defined quantity of a fluid 116 .

Fluid 116 can be a gas, for example an inert gas for rendering battery 102 inert, an oil, for example cooling oil for cooling battery 102, a cleaning liquid, for example for cleaning an interior of battery 102, or a combination of at least two of the examples mentioned .

In this example, the measuring device 108 is designed with a gas tank 118 , a pressure sensor system 120 and a computing unit 122 . The gas tank 118 holds a defined reference volume V _Ref of a gas 124 and is filled with a defined reference pressure p _Ref .

The gas 124 can be, for example, air, nitrogen, a forming gas or another suitable gas or another suitable gas mixture.

To carry out the aforementioned pressure measurement method, the gas container 118 can be opened in a step 210 (see 2 ) are fluidically coupled to the battery case 106 . The gas 124 flows through a corresponding housing opening 126 in the battery housing 106 into the interior of the battery housing 106. With the exception of the housing opening 126, the battery housing 106 can be sealed in a fluid-tight manner. After a certain time, a specific final pressure p _Ges is established in the fluidic system formed by the battery housing 106 and the gas container 118 .

In a step 220 the final pressure p _Ges is measured using the pressure sensor system 120 .

An example is the pressure sensor system 120 in 1 placed inside the gas tank 118 . Alternatively, the pressure sensor system 120 can also be placed at other points in the fluidic system. For example, the pressure sensor system 120 can also include a plurality of pressure sensors, which can be placed at different points in the fluidic system.

In a step 230, the measured end pressure p _Ges together with the known reference volume V _Ref and the known reference pressure p _Ref is suitably processed by the computing unit 122 . As a result of this processing, the arithmetic unit 122 outputs the volume V _G of the battery case 106 , which acts as an input to the controller 110 .

It is possible for steps 210, 220 and 230 to be performed following a leak test of the battery housing 106. The leak test can have been carried out, for example, using the measuring device 108 .

The volume V _G of the battery housing 106 can be calculated in step 230, for example, in the following way by the computing unit 122: $$V_G=\frac{p_{\text{ref}}\cdot V_{\text{ref}}}{p_{\text{total}}}-V_{\text{ref}}.$$

However, it is also possible for a corresponding value for the volume V _G based on the final pressure p _Ges to be read from a lookup table stored in the computing unit 122 .

Then, in a step 240, the control device 110 determines an amount of fluid with which the battery housing 106 is to be filled. The amount of fluid can be determined as a function of the measured volume V _G according to a predetermined ratio. For example, the amount of fluid can be 30, 60 or 90 percent of the volume V _G . However, any other ratios are also possible.

In an optional step 250, the amount of fluid may be further compared to a minimum amount of fluid by the controller 110 to determine whether the amount of fluid is sufficient or not.

The fluid quantity can be compared with the minimum fluid quantity, for example, taking into account a specific tolerance range.

If the amount of fluid corresponds at least to the minimum amount of fluid, then in a step 260 the control signal 112 can be generated in order to fill the battery housing 106 with the amount of fluid.

On the other hand, if the fluid quantity is below the minimum fluid quantity, a corrected fluid quantity can be determined in an optional step 270 . For this purpose, the amount of fluid can be increased by a specific correction value, for example. Accordingly, the control signal 112 may be generated at step 260 to fill the battery case 106 with the corrected amount of fluid.

As in 1 shown as an example, the filling device 114 can be designed with a fluid container 128, a fluid line 130 and a dosing device 132 for the controlled delivery of the fluid 116 from the fluid container 128 via the fluid line 130 into the battery housing 106. For this purpose, the fluid line 130 can be fluidically coupled to the housing opening 126 of the battery housing 106, for example. In this case, the dosing device 132 can be controlled by means of the control signal 112 .

For example, the battery housing 106 can still be sealed in a fluid-tight manner after it has been filled with the fluid 116 .

Since the devices and methods described in detail above are exemplary embodiments, the devices and methods can be modified to a large extent in the usual manner by a person skilled in the art without departing from the scope of the invention. In particular, the mechanical arrangements and the size ratios of the individual elements to one another are merely exemplary.

Reference List

100

manufacturing plant

102

battery

104

battery cell

106

battery case

108

measuring device

110

control device

112

control signal

114

filling device

116

Fluid

118

gas tank

120

pressure sensors

122

unit of account

124

gas

126

case opening

128

fluid container

130

fluid line

132

dosing device

210

Step of introducing a gas into the battery case

220

step of measuring a resultant ultimate pressure

230

Step of determining a volume of the battery case

240

Step of determining an amount of fluid

250

Step of determining whether the amount of fluid is sufficient or not

260

step of generating a control signal

270

Step of determining a corrected amount of fluid

ptotal

resulting final pressure

pRef

reference pressure

VG

Battery case volume

VRef

reference volume

Claims (12)

Method for filling a battery case (106) of a battery (102) with a fluid (116), the method comprising: determining a volume (V _G ) of the battery case (106) in a pressure measurement method; determining an amount of fluid to fill the battery case (106) from the volume (V _G ) of the battery case (106); and generating a control signal (112) for controlling a filling device (114) for filling the battery housing (106) with the fluid (116) based on the amount of fluid. procedure after claim 1 , wherein the pressure measurement method comprises: introducing a gas (124) from a gas container (118) into the battery housing (106), wherein the gas container (118) has a reference volume (V _Ref ) and is filled with a reference pressure (p _Ref ); Measuring a resulting final pressure (p _Ges ) of the gas (124) in the battery housing (106) and/or the gas container (118); Determining the volume (V _G ) of the battery housing (106) from the reference volume (V _Ref ), the reference pressure (p _Ref ) and the resulting final pressure (p _Ges ). procedure after claim 2 , where the volume (V _G ) of the battery case (106) is determined by: $$V_G=\frac{p_{\text{ref}}\cdot V_{\text{ref}}}{p_{\text{total}}}-V_{\text{ref}}.$$

where V _G stands for the volume (V _G ) of the battery housing (106), V _Ref for the reference volume (V _Ref ), p _Ref for the reference pressure (p _Ref ), p _Ges for the resulting final pressure (p _Ges ). A method according to any one of the preceding claims, further comprising: determining whether or not the amount of fluid is sufficient by comparing the amount of fluid with a minimum amount of fluid; if it is determined that the amount of fluid is sufficient: generating the control signal (112) based on the amount of fluid; and or if it has been determined that the amount of fluid is insufficient: determining a corrected amount of fluid by correcting the amount of fluid; generating the control signal (112) based on the corrected amount of fluid. Method according to one of the preceding claims, wherein the battery housing (106) is part of a high-voltage battery (106) for supplying an electric drive motor of a vehicle with electrical energy. A method according to any one of the preceding claims, wherein the control signal (112) is generated to fill the battery case (106) with an oil as the fluid (116). Procedure according to one of Claims 1 until 5 , wherein the control signal (112) is generated to fill the battery case (106) with an inert gas as the fluid (116). Manufacturing plant (100) for manufacturing a battery (102), the manufacturing plant (100) being configured to carry out the method according to any one of the preceding claims, the manufacturing plant (100) comprising: a measuring device (108) for determining the volume (V _G ) the battery case (106) in the pressure measurement process; and a controller (110) for determining the amount of fluid from the volume (V _G ) of the battery case (106) and for generating the control signal (112) based on the amount of fluid. Manufacturing plant (100) according to claim 8 , wherein the measuring device (108) comprises: a gas container (118) for introducing a gas (124) into the battery housing (106), wherein the gas container (118) has a reference volume (V _Ref ) and is filled with a reference pressure (p _Ref ). is; a pressure sensor system (120) for measuring a resulting final pressure (p _Ges ) of the gas (124) in the battery housing (106) and/or the gas container (118); a computing unit (122) for determining the volume (V _G ) of the battery housing (106) from the reference volume (V _Ref ), the reference pressure (p _Ref ) and the resulting final pressure (p _Ges ). Manufacturing plant (100) according to claim 8 or 9 , further comprising: a filling device (114) for filling the battery housing (106) with the fluid (116) by processing the control signal (112). Computer program comprising instructions that cause the manufacturing system (100) according to one of Claims 8 until 10 the procedure according to one of the Claims 1 until 7 executes Computer-readable medium on which the computer program claim 11 is saved.

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