Electric storage unit for a motor vehicle with a battery and an active cooling system

Abstract

An electrical storage unit (1) for a motor vehicle comprising several battery cells (3) of a battery (2) arranged in a housing (4) of the storage unit (1) on a housing base (7) and a cooling device for cooling the battery cells (3) in the housing (4), wherein the cooling device is designed to be connectable to a line system (11) for circulating a coolant, wherein the storage unit (1) is equipped on an outer wall surface (9) of the housing (4) facing away from the battery cells (3) below the battery cells (3) with a cooling element (10) through which the coolant flows, wherein the housing base (7) has a heat exchanger surface (18) impermeable to the coolant, characterized in that the cooling element (10) is designed as an open molded part with recesses (13) and at least one integrated inlet channel (14) and / or outlet channel (15), which has a circumferential,The outer wall surface (9) of the housing (4) has a sealingly connected edge area (16), wherein the molded part is open on one side, so that a closed piping system (11) is created by the connection with the outer wall surface (9), in which the coolant flows along the outer wall surface (9) of the housing (4).

Description

[0001] The invention relates to an electrical storage unit for a motor vehicle with a battery comprising several battery cells arranged in a housing of the storage unit on a housing base and with a cooling device for cooling the battery cells in the housing, wherein the cooling device is designed to be connectable to a line system for circulating the coolant and wherein the storage unit is equipped on an outer wall surface of the housing facing away from the battery cells below the battery cells with a cooling element through which the coolant flows, wherein the housing base has a heat exchanger surface that is impermeable to coolant.

[0002] Electrical energy storage units for motor vehicles, especially those with high-capacity batteries such as high-capacity lithium-ion batteries, are characterized by significant heat generation during control or normal operation.

[0003] Since batteries can only provide their optimal performance within a certain temperature range, it is usually necessary to provide an active cooling device that ensures a desired operating temperature and prevents the battery from overheating.

[0004] Under unfavorable conditions, one or more cells of a battery can be driven into a thermal runaway, also known as "thermal runaway" of the battery cell or the battery as a whole. This can be caused, for example, by excessive and potentially self-reinforcing heat production within a battery cell. To prevent or mitigate this adverse effect, the most efficient possible heat dissipation is necessary.

[0005] A commonly used cooling system in batteries utilizes a circulating coolant to cool the battery cells. The coolant is pumped from a heat exchanger (which regulates the coolant's temperature) through a pipe system and used to cool the battery cells. If increased cooling capacity is required, the pump can increase the coolant flow rate to enhance heat transfer within the battery.

[0006] A generic electrical storage unit for a motor vehicle is already known from DE 10 2012 209 306 A1, which describes a cooling system for battery cells. A temperature control system with a heat transfer medium serves to dissipate the waste heat from the battery via an existing air conditioning system, with the cooling elements being located outside the battery housing. The battery cells and / or the battery itself rest on a thermally conductive material, which can simultaneously serve as the housing wall.

[0007] US Patent 2014 / 0023906A1 relates to a power supply device for a hybrid or electric vehicle. In this device, the battery cells are stacked on an inner surface of an inner housing, which is cooled by a cooling plate. For this purpose, the cooling plate, containing a refrigerant circulating in a flat cooling tube, comes into contact with the base plate of the inner housing and is thermally coupled to the battery cells of the battery cell stack.

[0008] From DE 10 2010 042 460 A1, a battery enclosed in a housing is known, comprising several battery cells arranged within the housing and an active cooling device for cooling the battery cells. For this purpose, a coolant circulates in a pipe system, wherein a valve for the regulated and / or controllable evaporation of coolant from the pipe system is arranged in the pipe system to prevent the formation of overpressure in the pipe system. After opening the valve, coolant from the pipe system can evaporate. At the same time, this ensures heat transfer from the battery despite impaired pump function.

[0009] DE 10 2010 001 033 A1 relates to a battery comprising a plurality of battery cells, between each of which a heat storage plate is arranged, the material of which is essentially ceramic. The battery is associated with a cooling system, essentially designed as a base plate, with channels for the flow of a coolant, the cooling channels of the heat storage plate and the base plate advantageously being interconnected. The heat storage plates and the base plate are fluidly and mechanically coupled in a piping system.

[0010] Furthermore, a battery temperature control system is known from WO 2011 / 153 362 A1. In this system, a base comprises a fluid channel for a heat transfer fluid and a battery cell mounted on the base to change the temperature of the battery cell in response to a change in the temperature of the base. A base plate includes an internal cavity for an insulating material to reduce heat loss and ensure a uniform temperature distribution across the base plate, as well as one or more fluid flow or heat absorption channels.

[0011] A disadvantage of the known storage units is that, for example, due to accidental or wear-related damage, leaks can occur in the coolant circuit, especially in the piping system, and the coolant can come into contact with the battery cells, which can lead to a short circuit.

[0012] Furthermore, condensation on the wiring system leads to fluid residue inside the housing. This has already resulted in short circuits in the vehicle's electrical system in practice.

[0013] Efforts have already been made to counteract this adverse effect. These are based on measures such as oversizing the cooling system or improving the connections of the piping system.

[0014] Against this background, the invention is based on the objective of achieving optimal heat transfer.

[0015] This problem is solved with an electrical storage unit according to the features of claim 1. The dependent claims relate to particularly advantageous further developments of the invention.

[0016] According to the invention, an electrical storage unit is proposed in which the cooling element is designed as an open molded part with recesses and at least one integrated inlet and / or outlet channel, which has a circumferential edge region that is sealed to the outer wall surface of the housing. The molded part is open on one side, so that a closed piping system is created by the connection with the outer wall surface, in which the coolant flows along the outer wall surface of the housing. This makes the cooling element particularly easy to manufacture, as it is designed simply as a shell-like molded part with several recesses, for example, embossings. Because this molded part is open on one side, a closed piping system is only created by the connection with the outer wall surface.The coolant thus flows along the outer wall surface of the housing, so that optimal heat transfer can be achieved.

[0017] This design involves arranging the cooling element, and thus the entire active, liquid-flow-through cooling system, externally from the housing. Specifically, the cooling element, as a separate component, is thermally connected to the housing below its lower outer wall surface. This effectively prevents any escaping coolant from entering the housing and potentially causing damage, particularly a short circuit, in the electrical system. Instead, the escaping coolant is discharged into the environment. A sensor can, of course, be provided to detect the leak, for example, by monitoring a drop in the coolant level in a reservoir within the cooling system.

[0018] Furthermore, the cooling performance achievable in practice can be easily adjusted by replacing the cooling element without any changes to the housing, so that, for example, the climatic conditions at the vehicle's place of use can be taken into account accordingly.

[0019] It is particularly advantageous if the cooling element is equipped with thermal insulation on the side facing away from the housing. This prevents unwanted heating of the cooling element due to external influences and thus ensures optimal transfer of cooling power to the housing. Furthermore, the thermal insulation also serves as mechanical protection for the housing, effectively acting as a kind of underride guard.

[0020] The cooling element could be designed as a die-cast aluminum part with integrated cooling channels. However, it can also be manufactured particularly easily by using plastic, at least in part. This allows for greater design freedom in shaping the cooling element, enabling optimal adaptation of the cooling channels to the shape of the housing, as well as to the thermal requirements and temperature distribution.

[0021] Preferably, the cooling element is connected to the outer wall surface of the housing, in particular by an adhesive connection, so that they form an inseparable unit.

[0022] The housing can, in principle, have almost any shape. However, it is particularly practical if the housing is designed to protect against external influences by means of a lid and a seal, and in particular if it can be hermetically sealed, so that air exchange between the inside of the housing and the environment is prevented.

[0023] Furthermore, it proves particularly practical if the housing is made of sheet metal, at least in sections, preferably in the area of ​​the cooling element. This significantly improves thermal conductivity and thus heat transfer. In addition, the housing can be equipped with a suitable mounting bracket that allows for quick and reliable attachment of the cooling element to the housing.

[0024] Preferably, the housing may be made of a material comprising a polymer, a metal, a metal sheet or aluminum.

[0025] The cooling element can be easily adapted in shape and dimensions to different housings. It is also particularly advantageous if, according to a preferred modification, the cooling element is modularly expandable, so that the cooling capacity can be increased and adapted to specific requirements by adding one or more additional cooling elements. Preferably, the cooling elements can be connected directly to each other without additional connecting lines.

[0026] The invention allows for numerous embodiments. To further illustrate its basic principle, one of these is shown in the drawing and described below. This shows in Fig. 1 an electrical storage unit according to the invention in an exploded view; Fig. 2 a perspective view of a cooling element of the storage unit; Fig. 3 A cutaway side view of the electrical storage unit.

[0027] An electrical storage unit 1 according to the invention for a motor vehicle (not shown) is described below with reference to the Fig. 1, Fig. 2 to Fig. 3 explained in more detail. In it, it shows Fig. Figure 1 shows an exploded view of the essential structural and functional components of the storage unit 1, the central component of which is a battery 2 with several battery cells 3. These are enclosed by a housing 4 of the storage unit 1, which can be closed by means of a seal 5 with a lid 6 having cover insulation 17 and is thus protected against environmental influences. The battery cells 3 are arranged on a housing base 7 of the housing 4 and separated by partitions 8. On an outer wall surface 9 of the housing base 7 facing away from the battery cells 3, a cooling element 10 through which a coolant flows is provided below the battery cells 3 and is connected to a pipe system 11 for this purpose. The cooling element 10 is covered on its side facing away from the housing 4 by thermal insulation 12. The in Fig. The housing base 7 shown in Figure 3 thus simultaneously forms a heat exchanger surface 18 for the coolant, enabling efficient cooling of the battery cells 3. As shown in Figure 3, the housing base 7 also forms a heat exchanger surface 18 for the coolant, enabling efficient cooling of the battery cells 3. Fig.As can be seen in Figure 2, the cooling element 10 is designed as an open-topped molded part, with the coolant guided in several recesses 13. These recesses 13 are connected to an inlet channel 14 and an outlet channel 15 in such a way that almost the entire surface of the cooling element 10 can be exposed to the coolant. Along a circumferential edge 16 of the cooling element 10, it is sealed to the outer wall surface 9 of the housing 4 by means of a sealant (not shown), thus effectively preventing any unwanted leakage of coolant. In the event of deformation, for example due to an accident, and a resulting leakage, the battery 2 is separated from the coolant by the housing 4. In particular, this prevents the coolant from coming into contact with current-carrying parts of the battery cells 3. Reference symbol list 1 storage unit 2 batteries 3 battery cells 4 cases 5 Seal 6 lids 7 Case bottom 8 Partition wall 9 Exterior wall area 10 cooling elements 11. Piping system 12 Insulation 13. Shaping 14 Inlet channel 15 Outlet channel 16 Edge area 17 Cover insulation 18 heat exchanger surface area

Claims

[1] Electrical storage unit (1) for a motor vehicle comprising several battery cells (3) of a battery (2) arranged in a housing (4) of the storage unit (1) on a housing base (7) and a cooling device for cooling the battery cells (3) in the housing (4), wherein the cooling device is designed to be connectable to a piping system (11) for circulating a coolant, wherein the storage unit (1) is equipped on an outer wall surface (9) of the housing (4) facing away from the battery cells (3) below the battery cells (3) with a cooling element (10) through which the coolant flows, wherein the housing base (7) has a heat exchanger surface (18) that is impermeable to the coolant, characterized by, that the cooling element (10) is designed as an open molded part with recesses (13) and at least one integrated inlet channel (14) and / or outlet channel (15), which has a circumferential edge area (16) that is sealed to the outer wall surface (9) of the housing (4), wherein the molded part is open on one side, so that the connection with the outer wall surface (9) creates a closed piping system (11) in which the cooling fluid flows along the outer wall surface (9) of the housing (4). [2] Storage unit (1) according to claim 1, characterized by , that the cooling element (10) is equipped with thermal insulation (12) on its side facing away from the housing (4). [3] Storage unit (1) according to claim 1 or 2, characterized by , that the cooling element (10) is made of plastic at least in sections. [4] Storage unit (1) according to at least one of the preceding claims, characterized by, that the cooling element (10) is thermally connected to the outer wall surface (9) of the housing (4) by an adhesive connection. [5] Storage unit (1) according to at least one of the preceding claims, characterized by , that the housing (4) is designed to be protected against external influences by means of a cover (6) and a seal (5). [6] Storage unit (1) according to at least one of the preceding claims, characterized by , that the housing (4) is made at least partially of sheet metal. [7] Storage unit (1) according to at least one of the preceding claims, characterized by , that the cooling element (10) is designed to be modularly expandable.

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