Housing cover for energy storage module and method for assembling an energy storage module

Abstract

The present invention relates to a housing cover for a housing (4) for an energy storage module (1), which is provided for accommodating an arrangement of a plurality of energy storage cells (3), preferably prismatic energy storage cells or pouch energy storage cells, preferably lithium-ion energy storage cells, electrically interconnected via cell connectors (2), wherein the cell connectors (2) are connected to the terminals (302) of the respective energy storage cells (3) at contact points (303) by means of laser welding. According to the invention, at least one welding window (410) is provided in the housing cover (402) in the region of a contact point (303).

Description

The present invention relates to a housing cover for a housing for an energy storage module according to claim 1 and to a method for mounting an energy storage module with a corresponding housing cover according to claim 15.Technological BackgroundThe energy store is of substantial importance in the development of electrically driven means of transport, for example electric vehicles. For this purpose, energy storage modules with a high power and energy density are required. Energy storage modules can form an energy storage unit individually or also in a plurality of interconnected energy storage modules. Energy storage modules usually consist of a plurality of individual energy storage cells (e.g. lithium-ion battery cells) which are electrically connected to one another. Energy storage modules generally require temperature management in order to ensure their operation in an optimized temperature range. Energy storage cells typically have a narrow operating temperature range (e.g., between + 15° C. and +45° C.). The functional safety, service life and cycle stability of the energy storage cell and thus also the functional safety of the entire energy storage device depend on the energy storage cell not leaving this region. If the temperature exceeds a critical mark, a so-called "thermal runaway" can occur. In a thermal runaway, an intermittent chain reaction is initiated. In this case, the temperature rises extremely within milliseconds and the energy stored in the energy storage cell is released abruptly. Temperatures up to 400° C. can thus be formed. The contents of the energy store become gaseous and a fire occurs which is difficult to extinguish using conventional means. The risk of a thermal runaway begins from a specific temperature (e.g. 60° C.) and becomes extremely critical from a further temperature threshold (e.g. 100° C.). As a result, in energy stores, in particular energy stores for electric vehicles, an energy store management system is used, with which not only the charging and discharging behavior of the energy store cells is controlled or regulated, but measures are also taken with regard to temperature management and emergency management in the case of a thermal runaway. In order to ensure a targeted emission of gases during a thermal runaway, the energy storage cells sealed in a gas-tight manner have degassing openings. The degassing openings can be designed, for example, as predetermined breaking points which allow gases to escape from the interior of the energy storage cell to the environment starting from a certain internal pressure. The emerging gases may contain electrolytes which can react with water to give hydrofluoric acid. In order to reduce the risk for surrounding components and / or persons, such gases must be discharged in a controlled and targeted manner.For the electrical connection of the energy storage cells, energy storage modules have, as cell contacting elements, so-called cell connectors which, depending on the circuit type (serial or parallel), electrically connect two or more poles of two or more energy storage cells to one another. In the case of a series connection, for example, the anode of one energy storage cell is connected to the cathode of another energy storage cell. Energy storage modules can also have so-called module connectors as cell contacting elements, which serve to electrically connect individual energy storage modules to one another. In order to be able to monitor and regulate the state of charge of each energy storage cell, each cell connector can be electrically connected to the control and / or regulation electronics of the energy storage module. As a result, the cell voltage of each individual energy storage cell can be measured and the state of charge of the respective energy storage cell can be derived via the cell voltage. Furthermore, sensors, for example temperature sensors for monitoring the surface temperature of the energy storage cells, can also be provided, which are connected to the control and / or regulation electronics. The control and / or regulation electronics are located in an independent assembly in previous solutions.Moreover, for safety reasons, the cell connectors must be provided with contact protection against unintentional contact of the cell connectors with the hand.Background ArtDE 10 2019 213 450 B3 relates to a housing cover for an energy storage module according to the preamble of claim 1. For the electrical connection of the individual battery modules, a high-voltage connector is provided in each case, which is screwed or welded to the terminals of the respective battery module. The connecting region of the high-voltage connector to the terminal of the battery module is covered by a housing in order to avoid contact. Recesses are made in the housing for the passage of a welding tool.DE 20 2023 100 128 U1 teaches bus bar assembly for a battery pack, wherein the bus bar assembly comprises a bus bar and a bus bar holder, wherein the bus bar has a welding portion for welding to a terminal of a battery cell, and wherein the bus bar is mounted in the bus bar holder such that the welding portion is exposed from the bus bar holder. The welding can be carried out, for example, by laser welding.EP 3 660 945 B1 discloses a power supply device in which hot gases which emerge from degassing openings in the individual energy storage cells are discharged in a targeted manner along a degassing surface of individual energy storage cells via a degassing duct. This is achieved by a circuit board which is arranged opposite the individual degassing openings and running at a distance from them along the degassing surface. For protection from the hot gases, the circuit board is provided with a multi-layer heat protection layer.DE 10 2019 211 907 A1 describes a battery module having a housing formed from plastic, in which a fiber composite element is arranged circumferentially inside or outside the housing, wherein the fiber composite element is accommodated in a receptacle of end plates. The fiber composite element must be cured by means of the action of heat or UV radiation. A housing cover is screwed on the upper side of the housing. The interior of the housing is sealed fluid-tightly from the environment.DE 10 2020 135 026 B3 discloses a battery having a plurality of cells which are connected to one another via a first electrical cell connector and a second electrical cell connector. Furthermore, the battery has a battery inlet and a battery outlet for a temperature control medium. In this case, the first and second electrical cell connectors are directly in contact with the temperature control medium. Therefore, the temperature control medium is electrically insulating, so that the cells are not discharged via the temperature control medium.Object of the present inventionThe object of the present invention is to provide a housing cover for a housing of an energy storage module, which makes it possible to complete an energy storage module in a simple manner from a production standpoint.Solution of the ProblemThe above object is achieved by the features of claim 1 and claim 15. Practical embodiments of the present invention are claimed in the dependent claims.On account of the invention, cell contact elements, namely cell connectors, can be connected to the terminals of the respective energy storage cells in a simple manner at contact points by means of laser welding, since in each case at least one welding window for the passage of a laser beam through the welding window in the region of a contact point is provided in the housing cover. The housing cover can serve as a cell contacting system. This creates for the first time the possibility of carrying out a welding of the cell connectors to the terminals of the energy storage cells when the housing cover has already been mounted. As a result, the housing cover can advantageously already be fitted with further components to form a prefabricated mounting unit.The housing cover itself advantageously ensures the protection against contact of the electrical contacts and thus performs a dual function. For this reason, no separate assembly steps need to be taken to ensure contact protection. This allows the production process of an energy storage module to be considerably simplified.The at least one welding window is preferably dimensioned such that it is not possible to pass through it by means of a human finger or by means of a corresponding test finger.Because not only one but several welding windows are provided in the area of the respective contact point, on the one hand, an effective contacting by means of laser welding can be achieved, on the other hand, an improved contact protection for a contact point can be achieved compared to a single welding window with the same, i.e. corresponding, total passage area by the possible reduction of the dimension of the several welding windows.With regard to the contact protection, it is particularly advantageous if the welding windows are slit-shaped.Likewise particularly advantageous with regard to the contact protection, it is if the welding windows are designed to extend in a curved manner.Because the welding windows form a through-channel tapering from the top side toward the bottom side of the housing cover, the laser beam reflecting from the surface of the cell connector can emerge upward again through the welding window without components of the housing cover being damaged by the reflecting laser beam during the welding process.The taper angle is preferably defined depending on the process. It is preferably at least 20°, preferably at least 22.5°.By arranging a plurality of welding windows along a circular path or oval path, it can be achieved that the forces caused by the welding are distributed more uniformly and no substantial load peaks occur.Preferably, the welding windows have a width that ensures contact protection (by means of a finger of a hand). Preferably, the width is less than 2 mm.The welding windows can be arranged in the housing cover laterally, preferably on the outside, to the degassing channel and / or to the cooling channel. The degassing duct and / or the respective cooling duct is or are thus respectively located between rows of welding windows running along the energy storage module.According to a further embodiment, viewed in the cross section of the housing cover, the welding windows can be arranged between a first step or a first offset of the housing cover and the outer edge. The first step or the first offset creates a storage space on the inner side of the housing cover, which can be used to accommodate further functional components. This makes it possible, for example, for the respective welding window to be arranged in the immediate vicinity of the cell connector or module connector, even if a degassing duct or at least a portion thereof and / or at least one cooling duct is integrated into the housing cover.Viewed in the cross section of the housing cover, the welding windows can be arranged between a first step or the first offset of the housing cover and the outer edge.Viewed in the cross section of the housing cover, an air gap can be arranged between the upper side of the cell connectors and the opposite lower side of the welding window. Damage to the underside of the housing cover during the welding process is thereby avoided.Preferably, on the underside of the housing cover, contact projections can be formed laterally with respect to the welding windows, which contact projections rest on the cell connector. As a result, an air gap can be formed between the upper side of the cell connectors or module connectors and the opposite lower side of the housing cover.The housing preferably comprises a housing base body, which is in particular designed as a plastic molded part and forms an interior space, which is open in particular on one side, for accommodating energy storage cells, in particular lithium ion storage cells, and a housing cover, which is in particular designed as a plastic molded part and closes the open side of the interior space.The invention furthermore relates to a method for mounting an energy storage module having a housing according to at least one of Claims 1 to 12. According to the method according to the invention, the cell connectors are connected to the terminals of the respective energy storage cells at the contact points by means of laser welding after the housing cover has been placed on the housing base body filled with the energy storage cells. The laser beam for the laser welding of the cell connectors runs through the respective welding window. This makes it possible to simplify the manufacturing method of energy storage cells considerably by virtue of prefabricated mounting modules including the housing cover being able to be used.The laser beam can be directed perpendicularly to the cell connector during laser welding.Furthermore, during laser welding, the laser beam can be moved in sections along a circular path or oval path, wherein circular or oval path-running welding lines are produced.Before laser welding, the housing cover is positioned and / or fixed relative to the housing base body by means of holding means integrated into the latter in a specific position. As a result, the welding windows can be positioned or aligned exactly with respect to the respective contact points or welding positions before the laser welding takes place. This can be effected, for example, by the housing cover latching to the housing base body, for example when being lowered vertically onto the housing base body. This both simplifies the assembly and achieves the required quality of the laser welding of the cell connectors.Advantageously, the housing cover and the cell connectors can be provided as a prefabricated mounting unit.The prefabricated mounting unit can additionally comprise the following functional parts:at least one cooling channel, preferably two cooling channels, wherein the at least one cooling channel or the preferably two cooling channels are connected in particular integrally to the cell connectors and / or in particular integrally to the current tap or are made up as a module; and / orat least one degassing duct or constituents delimiting at least one degassing duct, and / orprotrusions as hold-downs for a printed circuit board and / ora current tap of the energy storage module, and / orat least one, preferably a plurality of, fastening lugs for fastening the energy storage module to a fastening substrate, and / orLatching means for ensuring a latching connection between the housing cover and the housing base body.DESCRIPTION OF THE INVENTION WITH REFERENCE TO EMBODIMENTSPractical embodiments of the present invention are explained in more detail with reference to drawing figures. Repeating features are provided with a reference numeral only once for the sake of clarity. The following are shown: FIG. 1 is a perspective view showing an example of an energy storage module having a case lid according to the present invention; FIG. 2 shows a simplified sectional illustration of the energy storage module in FIG. 1 ; FIG. 3 shows a perspective illustration of the housing base body of the housing of the embodiment according to FIG. 1 ; FIG. 4 shows a perspective illustration of the bracing strap injection-molded into the housing base body according to FIG. 3 ; FIG. 5 ashows a perspective illustration of an arrangement of a cooling channel comprising a plurality of cell contacting elements according to the energy storage module of FIG. 1 from above; FIG. 5 bshows a perspective illustration of the arrangement according to FIG. 5 afrom below; FIG. 6 is an enlarged sectional view of a part of the housing cover according to FIG. 1 ; FIG. 7 shows a perspective illustration of the cooling channel according to FIG. 5 abefore the introduction of the cell contact-making elements; FIG. 8 shows a perspective illustration of a cell contact-making element configured as a cell connector according to a first exemplary embodiment according to FIG. 1 ; FIG. 9 shows a perspective illustration of a cell contact-making element configured as a module connector according to a first exemplary embodiment according to FIG. 1 ; FIG. 10 shows a sectional view of a second exemplary embodiment of a cell contact element; FIG. 11 shows a sectional view of the arrangement according to FIG. 5 awith a cell contacting element according to the second exemplary embodiment according to FIG. 10 ; FIG. 12 shows an enlarged perspective illustration of a part of the housing cover according to the energy storage module of FIG. 1 in the region of the welding windows; FIG. 13 shows a plurality of welding windows of a contact point arranged along a circular path in plan view; FIG. 14 shows an enlarged illustration of a part of the housing cover in the region of the welding windows in a sectional illustration, and FIG. 15 shows an illustration of the course of the laser cone for laser welding through the welding windows of FIG. 13.FIG. 1 shows an example of a housing 4 for an energy storage module 1 for prismatic energy storage cells or so-called pouch energy storage cells. For example, these are lithium-ion energy storage cells. Such energy storage modules are used, for example, for electrically operated vehicles, e.g. electric cars. Usually, in an electrically driven vehicle, a plurality of energy storage modules 1 are used, which are electrically interconnected to one another.According to the invention, the housing 4 comprises a housing base body 401 and a housing cover 402 fastened to the upper side of the housing base body 401. The housing base body 401 and the housing cover 402 are designed as plastic molded parts (injection molded parts) in order to ensure the lowest possible weight of the energy storage module 1.The housing 4 of the energy storage module 1 has an elongate, cuboidal shape. Along the housing cover 402, a plurality of connecting means are provided on both sides of the housing cover 402, respectively. These serve to mechanically connect the housing cover 402 to the housing base body 401. Preferably, the connecting means can each be a snap connection 408. Furthermore, a plurality of welding windows 410 are also located on both sides of the housing cover 402, the significance of which will be described below.A printed circuit board 7 projects in the end-face region of the energy storage module 1, by means of which printed circuit board signals from sensors can be provided for a battery management system (BMS) (not shown in FIG. 1 ). In the energy storage module 1, there is a degassing duct 5 and two cooling ducts 6, which are each arranged below the housing cover 402. The direction of degassing within the scope of a critical situation in which gases escape from the interior of an energy storage cell as a result of an overpressure which arises is reproduced by way of example with the two arrows marked in FIG. 1.In the end-face region of the energy storage module 1, a transition (not shown in the drawing figure) can be provided between the two laterally located cooling channels 6. The lateral cooling channels 6 are each connected via a connection channel 612 to a cooling channel of a further energy storage module (not shown) or to a cooling system (likewise not shown). A cooling medium from the cooling system can be supplied to the energy storage cell 1 by means of the cooling duct 6.On the housing base body 401, protruding laterally, through-openings 411 with tubular hole amplifiers located therein for fastening the energy storage module 1 on a base plate (not shown in FIG. 1 ) are formed integrally into the housing base body 401. As a result, the completed energy storage module 1 can be mounted on a base plate, for example by means of a screw connection. Reference numeral 223 denotes a current tap of a module connector 220.FIG. 2 shows a sectional view through the internal structure of the energy storage module 1 according to FIG. 1 Inside the housing 4 of the energy storage module 1 there is a plurality of energy storage cells 3, which are equipped with respective terminals 302 in the region of the upper side illustrated in FIG. 2. On the top side of the terminals 302 are the respective cell contacting elements in the form of cell connectors 2 which connect adjacent energy storage cells 3 of an energy storage module 1 to one another.Degassing openings 301 indicated in FIG. 2 are provided in the energy storage cells 3. These are specially designed openings which open automatically when an overpressure builds up in the interior of the energy storage cell 3 is exceeded and allow hot gas to escape. In order to prevent the hot gas from being able to pass into the interior of the passenger compartment, a degassing duct 5 is provided, via which the escaping hot gas can be directed away in two directions, as illustrated for example by the arrows in FIG. 1. Furthermore, at the end of an energy storage module 1, a main collecting duct (not shown in the drawings) can be located, through which the hot gas can be discharged in a targeted manner to the vehicle outer side.The energy storage module 1 or its housing cover 402 preferably forms a fluid-tight interface with such a main collecting channel. If two energy storage modules 1 are coupled to one another, the hot gas can also be conducted via the degassing duct 5 of the adjacent energy storage module 1 to a main collecting duct. The degassing openings 301 of the individual energy storage cells 3 form a degassing surface on the upper side of the arrangement of the energy storage cells 3, which degassing surface lies opposite the housing cover 402 at a distance, such that the cavity between the housing cover 402 and the degassing surface of the individual energy storage cells 3 forms the degassing duct 5. By completing the housing cover 402 on the housing base body 401, which is open on one side and filled with the energy storage cells 3, the degassing channel 5 can thus also be formed simultaneously in a simple manner.Due to the construction, the housing cover 402 can be provided in the region of the degassing duct 5 in a simple manner with a lining 407 made of a heat-resistant and / or flame-resistant material. The lining 407 can expediently extend as far as the degassing surface of the energy storage cells 3. The lining 407 can either be adhesively bonded into the housing cover 402 or fastened to the latter by means of welding. Alternatively, the housing cover 402 can also be a multi-component injection molded part, in which the lining 407 is introduced as an injection molded component immediately during the production process or a corresponding insert is injection molded.A cooling channel 6 is located laterally with respect to the degassing channel 5, The cooling channel 6 can have a U-shaped configuration and dips with its open side positioned upward into a groove-shaped, underside recess 406 of the housing cover 402. The respective cooling channel 6 serves to cool the cell connectors 2 by means of a cooling fluid located therein, which is supplied as a feed line via a connection channel 612. The housing cover 402 can thus also be designed with corresponding cooling channels 6 as a prefabricated component. When the housing cover is assembled, the cooling channels 6 are thus advantageously also integrated into the energy storage module 1 at the same time.The respective cell connector 2 extends horizontally into the region of the respective cooling channel 6, such that the cooling fluid exerts a cooling effect on the part of the cell connector 2 extending into the region of the cooling channel 6 and thus on the cell connector 2 as such. The cell connector 2 can be arranged here, as shown in FIG. 2, so as to extend into the lower wall of the U-shaped cooling channel 6. Alternatively, it can also extend directly into the cavity of the cooling channel 6 through which cooling medium flows (cf. FIG. 11 ).Below the respective cooling channel 6 there is a printed circuit board 7, by means of which signals can be provided for a battery management system (BMS) (not shown in FIG. 1 ). Signals from sensors (e.g. temperature sensors, gas sensors, pressure sensors) (not shown in the figures) for the battery management system (BMS) or for a control unit can be provided, for example, via the printed circuit board 7. According to FIG. 1, the printed circuit board 7 protrudes somewhat on the narrow end face of the energy storage module 1, so that data or signal tapping can take place there. The printed circuit board 7 is loosely inserted and is held in position by underside projections 608 of the cooling channel 6. The printed circuit board 7 can preferably be a flexible printed circuit board (i.e. a so-called flex conductor).Furthermore, as can be seen in FIG. 1, the current tap 223 of the energy storage module 1 protrudes on the narrow end face of the energy storage module 1 as part of the module connector 220 (FIG. 9 ). The current tap 223 is located between a fastening tab 420 and the through-opening 411. Via the current tap 223, the energy storage module 1 can be connected to further energy storage modules, not shown, or to an electrical load, not shown, for example an electric motor of an electric vehicle.According to FIG. 2, the housing cover 402 has a respective first step 403 laterally with respect to the degassing channel 5, so that the housing cover 402 is located laterally with respect to the region of the cooling channel 6 with the respective cell connector 2 in the region of the terminals 302. Offset inwardly relative to the first step 403 is a web 405 which, together with the first step 403, forms a groove-shaped recess 406 for receiving the cooling channel 6. The two webs 405 also form a contact surface for the lateral regions of the lining 407 and delimit the degassing channel 5 laterally.Furthermore, the housing cover 402 can have a second step 404 laterally with respect to the first step 403, such that the housing cover 402 engages laterally around the outer region of the respective cell connector 2. Furthermore, a vertically extending projection 409 and a circumferential edge 418, which engages laterally vertically, can be provided in the edge region of the housing cover 402, said projections positioning or centering the housing cover 402 in its position with respect to the housing base body 401.The above-described construction of the energy storage module 1 ensures a considerable simplification of the production-related assembly in comparison with previously known energy storage modules.FIG. 3 shows the structure of the housing base body 401 as an independent part of the invention. The housing base body 401 is a housing base body 401, which is designed as a plastic molded part and has a substantially rectangular shape. A bracing strap 8 comprising a plurality of fibers (not shown in FIG. 3 ) extends within the housing base body 401, said strap serving to absorb bracing forces of the energy storage cells 3. The bracing strap 8 is injection-molded in the housing base body 401. The injection molding of the bracing strap 8 results in a replacement-free omission of individual parts for the purpose of holding the same. The bracing strap 8 prevents the housing base body 401 from being widened during cell breathing (so-called swelling).The bracing strap 8 extends between a side wall 417 and inside retaining webs 413, 414 of the housing base body 401, which are located along the entire circumference of the housing base body 401. According to FIG. 2, the bracing strap 8 can be located in an inner recess 412 of the side wall 417. The retaining webs 413, 414 extend from an upper side of the housing base body 401 to the lower side thereof and are provided on all four sides. The retaining webs 413, 414 define the exact position where the energy storage cells 3 are used. Each energy storage cell 3 abuts, for example, a lateral retaining web 413.The retaining webs 414 located in the end face region are wedge-shaped. After the energy storage cells have been inserted into the housing base body 401, a loose clamping wedge 415 can be driven in along the wedge-shaped retaining webs 414 for clamping between the arrangement of the energy storage cells 3 and the housing base body 401, and thus ensures clamping of the clamping wedge 415 in the z direction or in the direction of the housing top side. In the side region, latching hooks 416 are located as part of the connecting means or snap connection 408 described at the beginning. The housing base body 401 and the housing cover 402 consist of a thermoplastic material.FIG. 4 shows the tensioning belt 8 as a prefabricated component, in which fibers (not shown) as continuous fibers are wound multiple times around the circumference of the tensioning belt 8. For example, the bracing band 8 can be designed as a pre-fixed, frame-like insert-molded component containing the fibers. For this purpose, the bracing tape 8 is produced, for example, by means of a tape laying process or by means of a winding process, for example as a unidirectional tape.FIGS. 5 aand 5 b show an arrangement 9 with a plurality of cell contact-making elements configured as cell connector 2, a cell contact-making element configured as module connector 220 and the cooling duct 6. The cell connector 2 serves for the electrical contacting of two energy storage cells (not shown in FIGS. 5 aand 5 b) via a first contact surface 212 and a second contact surface 213. The module connector 220 serves for the electrical contacting of an energy storage cell (not shown in FIGS. 5 aand 5 b ) arranged at an end-side end of the energy storage module 1 via a contact surface 222. The module connector 220 comprises the current tap 223.FIG. 6 shows an enlarged sectional illustration of a part of the housing cover 402 according to FIG. 1 with the arrangement 9, in which the cell contacting element 2, 220 is embedded or embedded within a lower wall 607 of the cooling channel 6.It can be seen from FIGS. 5 a- 6 that the cell contact elements 2, 220 are connected to the cooling channel 6 or embedded therein via a melting region 613. The cell contact-making elements 2, 220 each comprise a first side 215, 225 (not shown in FIGS. 5 aand 5 b) and a second side 216, 226, wherein only the first side 215, 225 of the cell contact-making elements 2, 220 is connected to the cooling duct 6 at least in regions or is embedded therein at least in regions. In this case, the first side 215, 225 of the cell contact-making elements 2, 220 according to the first exemplary embodiment of the arrangement 9, cf. FIG. 6, is embedded in a lower wall 607 of the cooling duct 6. In this case, the cell contact-making elements 2, 220 do not project into the interior of the cooling duct 6. In this case, the cell contact-making elements 2, 220 do not have to be protected against a corrosive and / or electrically conductive cooling fluid. Alternatively, the first side 215, 225 of the cell contact-making elements 2, 220 can also project through a first side wall 605 of the cooling duct 6 into the interior of the cooling duct 6, cf. FIG. 11.Advantageously, the cooling channel 6 and the cell contact elements 2, 220 can thereby be connected to form a common assembly which can be mounted as a prefabricated assembly in an assembly step in each case on the housing cover 402, in particular bonded at joints 609, cf. FIG. 6 or 11.The first side wall 605, a second side wall 604 and the lower wall 607 of the cooling channel 6 can be seen in FIGS. 5 a- 7. In the upper region, the cooling channel 6 has an opening 606 which extends along the entire cooling channel 6. In this case, the cooling channel 6 has a U-shaped cross section open towards the top. Alternatively, the cooling channel 6 may include an upper wall instead of the upper side opening 606, such that the cooling channel 6 has a closed quadrangular cross section.The cooling channel 6 has a plurality of projections 608 on the bottom wall 607, cf. FIGS. 5 band 6. The printed circuit board 7 is arranged below the projections 608. The printed circuit board 7 can be pressed against a substrate by the projections 608 and can thereby be held in position. This has the advantage that, by assembling the components, the cooling channel 6 fixes the circuit board 7 in its position and, as a result, a further assembly step can be saved.As can be seen from FIGS. 5 a- 7, the cooling channel 6 additionally comprises a first end-face opening 601 and a second end-face opening 602. The first opening 601 and the second opening 602 each have a round flow cross section. The cooling channel 6 can be connected via the first opening 601 and the second opening 602 to a cooling system, not shown, via the connection channel 612, cf. FIG. 1.The cooling channel 6 is preferably glued to the housing cover 402 in a fluid-tight manner at the joints 609. In this case, the housing cover 402, in the case of a U-shaped profile of the cooling duct 6, simultaneously forms the upper wall of the cooling duct 6 and closes the opening 606. For this purpose, two joints 609 preferably extend along the complete longitudinal extent of the cooling channel 6. As a result, the first side wall 605 and the second side wall 604 are bonded at their respective end sides to the housing cover 402. Thus, the preferably fluid-tight adhesion at the joints 609 ensures that no cooling fluid enters from the cooling channel 6 into the interior of the housing 4.FIG. 8 shows a perspective view of the cell contact element configured as a cell connector 2. The cell connector 2 comprises an electrically conductive base body 211 designed as a flat material or as a stamped part. The base body 211 comprises the first contact surface 212 for electrically contacting a terminal 302 of the energy storage cell 3 and the second contact surface 213 for electrically contacting a terminal (not shown in the figures) of a second energy storage cell (not shown in the figures). In this case, the first and the second contact surfaces 212, 213 are connected, in particular welded, to the terminal 302 of the first energy storage cell 3 or to the terminal of the second energy storage cell. The first side 215 of the cell connector 2 comprises a region connecting the contact surfaces 212, 213.The first and the second contact surface 212, 213 are separated from one another by a recess 219. As a result, the current flow is shifted in the direction of the first side 215. Since the first side 215 may be arranged in the cooling channel 6, the cell connector 2 may be cooled particularly effectively.The cell contact element designed as a module connector 220 comprises an electrically conductive base body 221 according to FIG. 9. The base body 221 comprises the contact surface 222 for electrically contacting a terminal (not shown in the figures) of an energy storage cell (not shown in the figures) preferably arranged at an end-face end of the energy storage module 1. The contact surface 222 is connected, in particular welded, to the terminal. In addition, the module connector 220 comprises the current tap 223 with a through hole 229 for fastening the current tap 223, for example via a screw connection, to the housing 4.According to a first exemplary embodiment, the base bodies 211, 221 of the cell contact-making elements 2, 220 are a bare, in particular uncoated, body. In this case, the electrically conductive base body 211, 221 of the respective cell contact-making element 2, 220 can be in direct contact with a wall of the cooling duct 6. In addition, when using a non-electrically conductive cooling fluid, the electrically conductive base body 211, 221 of the respective cell contacting element 2, 220 can project into the cooling channel 6. This achieves an effective cooling effect.FIG. 10 shows a cross section of the cell contact elements 2, 220 according to a second exemplary embodiment. According to the second exemplary embodiment, a partial region 214, 224 of the cell contact-making elements 2, 220 or of the respective base bodies 213, 223 is coated with a planar coating 217, 227, wherein the partial region 214, 224 extends over the entire first side 215, 225 of the cell contact-making elements 2, 220.FIG. 11 shows a sectional view of the coated cell contacting element 2, 220 according to the second exemplary embodiment according to FIG. 10 in an arrangement 9. The cooling fluid thus flows around coated partial region 214, 224 of cell contact element 2, 220. This can ensure direct cooling of the cell contacting element 2, 220.It is particularly advantageous in this case if the coating 217, 227 is a thermally conductive, electrically insulating material, in particular a thermally conductive, electrically insulating plastic. As a result, the cell contact-making element 2, 220 is insulated by the coating 217, 227, wherein electrically conductive cooling fluid can also be used. The coating 217, 227 preferably additionally has adhesion-supporting properties, such that the respective cell contact-making elements 2, 220 can adhere directly to the cooling duct 6 or its wall without additional adhesive.The coating 217, 227 has in particular a thickness 218, 228 of less than 0.5 mm, preferably less than 0.4 mm, particularly preferably less than 0.3 mm.The cell contact elements 2, 220 are permanently connected to one another with the cooling channel 6 without additional fastening means to form a one-piece assembly. This can be a method in which the wall of the cooling channel 6 is brought into a plastic state in some areas by targeted heating, so that the cell contacting element 2, 220 is pushed through the wall or an opening of the wall. The heating can be effected, for example, by a laser beam or by ultrasonic oscillations.When the wall of the cooling channel 6 is heated by means of ultrasound, an ultrasonic vibration is introduced into at least one subregion of the cooling channel 6 and the latter is heated up to its melting point. Expediently, the partial region is provided on the first side wall 605 or on the bottom wall 607. In this case, the at least one partial region is arranged in particular at the positions at which a cell contacting element 2, 220 is to be positioned in each case. As a result, only that portion of the cooling channel 6 is heated and melted at which a cell contacting element 2, 220 is to be connected to the cooling channel 6. In the case of a plurality of cell contact-making elements 2, 220, a plurality of subareas of the cooling channel 6 are provided in particular, into which the ultrasonic vibration is introduced.The ultrasonic vibration is expediently introduced into the partial region of the cooling channel 6 via the cell contacting elements 2, 220, such that only the contact region of the cooling channel 6 through which a cell contacting element 2, 220 is intended to be introduced into the cooling channel 6 is melted.Alternatively, the ultrasonic vibration, in particular at the positions predetermined for the cell contacting elements 2, 220, can be introduced into the cooling channel 6 by an ultrasonic vibration transmitter, e.g. a sonotrode.The cell contacting elements 2, 220 are introduced into the cooling channel 6 after the respective partial region of the cooling channel 6 has been heated. In this case, for example, the heated first side wall 605 is pierced by the cell contact-making element 2, 220. Alternatively, the cell contacting element 2, 220 is pushed into the heated lower wall 607 of the cooling channel 6. The fused partial region in this case merges the corresponding cell contact element 2, 220. Subsequently, the introduction of the ultrasonic vibration is ended and the partial region of the cooling channel 6 solidifies. This forms the melting region 613 running around the respective cell contact elements 2, 220. The melting region 613 ensures a fluid-tight connection, so that no cooling fluid can enter from the cooling channel 6 into the interior of the housing 4 at the melting region 613.Alternatively, in each case either in the first side wall 605 or in the bottom wall 607, a recess is provided in the cooling channel 6 at the predetermined position for the respective cell contacting element 2, 220, into which recess the corresponding cell contacting element 2, 220 can be pushed. In this case, in particular only the edge regions of the recesses are melted. The melted edge regions of the recesses then remelt the cell contact elements 2, 220 pushed into the respective recesses and form the melting region 613 after solidification. The cell contact-making elements 2, 220 preferably project through the first side wall 605 into the interior of the cooling channel 6.Alternatively, instead of a recess, a through opening, preferably of somewhat smaller dimensions in comparison to the respective cell contacting element 2, 220, can also be provided in the region of the first side wall 605, the edge region of which is melted in the manner described above and in this case also the cell contacting elements 2, 220 extend through the first side wall 605 into the interior of the cooling channel 6.As an alternative to the ultrasonic method, the cell contacting elements 2, 220 can be injection molded with the cooling channel 6 as an injection molded part during the production of the cooling channel 6. By injection molding around the cell contacting elements 2, 220, a fluid-tight connection is formed between the cell contacting elements 2, 220 and the cooling channel 6.FIG. 12 shows a part of the housing cover 402 of the energy storage module 1 in the region of the welding windows 410 in an enlarged illustration. The welding windows in the housing cover 402 represent an independent contribution of the invention. In the embodiment shown in FIG. 12, a plurality (e.g. four) of welding windows 410 are provided per contact point 303, respectively. The welding windows 410 are arranged on each side of the housing cover 402 between the first step 403 or the first offset and the outer edge region of the housing cover 402 in the longitudinal direction of the energy storage module 1, preferably at a constant distance from one another.Furthermore, FIG. 12 also shows the second step 404 or the second offset, the molding for ensuring the snap connection 408 and the fastening tab 420. The fastening tab 420 is located at the position on the housing cover 402, which corresponds to the position of the through-opening 411 on the housing base body 401. The energy storage module 1 can be fixed via the fastening tab 420 on a mounting surface, not shown in the figures, for example by means of a screw (not shown). In the example of an energy storage module 1 shown in FIG. 4, a total of four fastening tabs 420 are provided in the end-face region of the housing cover 402.The welding windows 410 are arranged in the housing cover 402 laterally along the degassing channel 5 and laterally with respect to the cooling channels 6 in a row in each case.As can be seen from FIG. 13, the individual welding windows 410 preferably have a gap-shaped form, are designed to extend in a curved manner and lie along a circular path 425. The width of the welding windows 410 is preferably less than 2 mm.The welding windows 410 form a through channel tapering from the top side toward the bottom side of the housing cover 402, as can be seen from FIG. 14. As a result, after the laser beam enters, the laser beam reflecting from the surface of the cell connector can emerge upward again through the welding window 410 without components of the housing cover 402 being damaged by the reflecting laser beam during the welding process.Preferably, the taper angle relative to the perpendicular is at least 20°, preferably at least 22.5°. The tapering takes account of the fact that the laser beam is reflected at the surface of the cell connectors 2 during a perpendicular passage through the welding window 410, which is expressed by the illustration according to FIG. 15. The illustration therein shows the cone-like shape of the reflected laser beam 10 and the respective range of movement 101 of the laser beam 10 along a circular path for carrying out the laser welding in the embodiment of the welding windows according to FIG. 13, FIG. 15 shows the reflection of the laser beam 10 on the reflecting surface of the cell connector 2 described above.As an alternative to a circular path, a plurality of welding windows can also be arranged along an oval path at a contact point 303. By arranging a plurality of welding windows along a circular path or oval path, it is achieved that the forces caused by the welding are distributed more uniformly and no substantial load peaks occur.As can be seen from FIG. 14, an air gap 423 is located between the upper side of the cell connectors 2 and the opposite underside of the welding window 410, which air gap prevents damage to the underside of the housing cover 402 during the welding process. To ensure the air gap 423, contact projections 424 are formed on the underside of the housing cover 402, laterally with respect to the welding windows 410, which contact projections rest on the cell connector (not shown in FIG. 14 ). As a result, the air gap 423 can be formed between the upper side of the cell connectors and the opposite lower side of the housing cover 402.The measure of using welding windows 410 in the housing cover 402 enables an advantageous method for mounting the energy storage module 1, wherein the cell connectors 2 are connected to the terminals 302 of the respective energy storage cells 3 at the contact points 303 by means of laser welding after the housing cover 402 has been placed on the housing base body 401 filled with the energy storage cells 3, wherein the laser beam 10 for the laser welding runs through the respective welding window 410. The laser beam 10 is directed perpendicularly onto the cell connectors 2 or module connectors 220.The snap connection 408 between the housing cover 402 and the housing base body 401 enables a simple-to-manipulate fixing of the housing cover 402 on the housing base body 401 and at the same time a prealignment of the welding windows 410 with respect to the relevant contact points 303.The aforementioned procedure makes it possible to provide the housing cover 402 and the cell connectors as a prefabricated mounting unit.In addition, the prefabricated mounting unit, which comprises the housing cover 402 and the cell connectors 2 or module connectors 220, can additionally comprise functional components, such as, for example, the following functional components: at least one cooling duct 6, preferably two cooling ducts 6, wherein the at least one cooling duct 6 or the preferably two cooling ducts 6 can be connected in particular integrally to the cell connectors 2, as illustrated in FIGS. 5 a, 5 b, and preferably integrally to the module connector 220. In addition, the degassing duct 5 or at least components lining the degassing duct, such as the lining 407, can be a component of the prefabricated assembly unit. By means of the module connector 220, the current tap 223 of the energy storage module 1 can also be part of the prefabricated mounting unit; the same applies to the fastening tabs 420 for fastening the energy storage module 1 on a fastening substrate (not shown). In addition, holding means such as, for example, latching means can be provided on the housing cover 402 in order to ensure a snap connection between the housing cover 402 and the housing base body 401.All in all, the use of welding windows offers considerable advantages with regard to carrying out the assembly sequence of an energy storage module 1.The present invention thus makes a considerable contribution to the relevant field of technology.LIST OF REFERENCE CHARACTERS1 Energy storage module 2 Cell connector 211 Base body 212 Contact surface 213 Contact surface 214 Partial region 215 First side 216 Second side 217 Coating 218 Thickness 219 Cutout 220 Module connector 221 Base body 222 Contact surface 223 Current tap 224 Partial region 225 First side 226 Second side 227 Coating 228 Thickness 229 Through hole 3 Energy storage cell 301 Degassing opening 302 Terminal 303 Contact point 4 Housing 401 Housing base body 402 Housing cover 403 First step 404 Second step 405 Web 406 Recess 407 Lining 408 Snap connection 409 Projection 410 Welding window 411 Through opening 412 Recess 413 Retaining web 414 Retaining web 415 Clamping wedge 416 Latching hook 417 Side wall 418 Edge 419 Wall slope 420 Fastening tab 421 Central part 422 Web 423 Air gap 424 Contact projection 425 Circular path 5 Degassing channel 6 Cooling channel 601 Opening 602 Opening 604 Side 605 Side 606 Opening 607 bottom 608 projection 609 joint 612 connection channel 613 melting region 7 printed circuit board 8 clamping band 9 arrangement 10 laser beam 101 movement region laser beam 13 degassing opening B width welding window

Claims

Housing cover for a housing (4) for an energy storage module (1), which is provided for accommodating an arrangement of a plurality of energy storage cells (3) electrically interconnected via cell connectors (2), preferably prismatic energy storage cells or pouch energy storage cells, preferably lithium ion energy storage cells, characterized in that the cell connectors (2) are connected to one another at contact points (303) by means of laser welding to the terminals (302) of the respective energy storage cells (3), and wherein at least one welding window (410) is provided in the housing cover (402) in the region of a contact point (303).Housing cover according to claim 1, characterised in that the housing cover (402) forms, in the region of the respective contact point (303), a contact protection against accidental contact of the contact point when the housing (4) is closed.Housing cover according to Claim 1 or 2, characterized in that a plurality of welding windows (410) are provided in the region of the respective contact point (303).Housing cover according to at least one of the preceding claims, characterized in that the welding windows (410) are gap-shaped.Housing cover according to at least one of the preceding claims, characterized in that the welding windows (410) are designed to extend in a curved manner.Housing cover according to at least one of the preceding claims, characterized in that the welding windows (410) form a through-channel which narrows from the upper side towards the lower side of the housing cover (402).Housing cover according to claim 6, characterised in that the taper angle is defined depending on the process, preferably at least 20°, particularly preferably at least 22.5°.Housing cover according to at least one of the preceding claims, characterized in that a plurality of welding windows (410) are arranged along a circular path or oval path.Housing cover according to Claim 6, characterized in that the welding windows (410) have a width B which ensures contact protection.Housing cover according to at least one of the preceding claims, characterized in that the welding windows (410) in the housing cover (402) are arranged laterally along a degassing duct (5) and / or laterally along at least one cooling duct (6).Housing cover according to at least one of the preceding claims, characterized in that, viewed in the cross section of the housing cover (402), the welding windows (410) are arranged between a first step (403) of the housing cover (402) and the outer edge.Housing cover according to at least one of the preceding claims, characterized in that, viewed in the cross section of the housing cover (402), an air gap (423) is arranged between the upper side of the cell connectors (2) and the opposite underside of the welding window (410).Housing cover according to at least one of the preceding claims, characterized in that contact projections (424) are provided on the underside of the housing cover (402) laterally with respect to the welding windows (410), said contact projections resting on the cell connector (2).Housing cover according to at least one of the preceding claims, characterized in that the housing (4) encloses the arrangement of the energy storage cells (3), in particular with formation of a compressive stress on the arrangement of the energy storage cells, wherein the housing (4) comprises a housing base body (401), which is in particular formed as a plastic moulded part and forms an interior space for receiving the energy storage cells (3), and a housing cover (402), which is in particular formed as a plastic moulded part and closes an open side of the interior space.Method for mounting an energy storage module (1) with a housing cover according to at least one of the preceding claims, characterized in that the cell connectors (2) are connected to the terminals (302) of the respective energy storage cells (3) at the contact points (303) by means of laser welding after the housing cover (402) has been placed on the housing base body (401) filled with the energy storage cells (3), wherein the laser beam (10) for the laser welding runs through the respective welding window (410).Method according to claim 15, characterised in that the laser beam (10) is directed perpendicularly to the cell connector (2).Method according to claim 16, characterised in that the laser beam (10) is moved in sections along a circular path or oval path.Method according to at least one of Claims 15 to 17, characterized in that the housing cover (402) latches to the housing base body (401) when it is lowered vertically onto the housing base body (401).Method according to at least one of Claims 15 to 18, characterized in that the housing cover (402) and the cell connectors (2), preferably the housing cover (402), the cell connectors (2) and the module connectors (220), are provided as a prefabricated mounting unit.Method according to Claim 19, characterized in that the prefabricated mounting unit additionally comprises the following: at least one cooling duct (6), preferably two cooling ducts (6), wherein the at least one cooling duct (6) or the preferably two cooling ducts are connected in particular integrally to the cell connectors (2) and / or in particular integrally to the power tap (223); and / or at least one degassing duct (5) or at least one constituents delimiting a degassing duct (5), and / or projections (608) as hold-downs for a printed circuit board (7) and / or a power tap (223) of the energy storage module (1), and / or at least one, preferably a plurality of, fastening lugs (420) for fastening the energy storage module (1) on a fastening base, and / or latching means for ensuring a latching connection between housing cover (402) and the housing base body (401).

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