Motor vehicle with a traction battery

Abstract

Motor vehicle (1) with a traction battery (2), wherein the traction battery (2) is accommodated in a motor vehicle body (3) comprising a body shell (4) and an underbody (5), and wherein the traction battery (2) is designed for an electric drive (11), and wherein a cooling system (12) is provided for cooling the electric drive (11), characterized in that, for cooling the traction battery (2), which is arranged in a cavity (7) formed between the body shell (4) and the underbody (5), an underbody element (14) of the underbody (5) has a passage opening (15) which can be opened or closed by means of a closing element (17), wherein air can flow into the cavity (7) via the passage opening (15), and can flow around the traction battery (2) for cooling by convection.

Description

[0001] The invention relates to a motor vehicle with a traction battery according to the preamble of claim 1.

[0002] Motor vehicles with traction batteries are known. Typically, the vehicle has an electric drive in the form of an electric motor, which is powered by the traction battery. The traction battery, for example, has an energy storage system in the form of a multitude of battery modules, each containing a plurality of battery cells. The plurality of battery cells are bundled into a battery module, with several battery modules being housed in a battery casing of the traction battery. The traction battery is housed in a compartment within the vehicle body. Typically, the traction battery and the electric motor, both of which generate heat during operation, are cooled by means of a cooling system.

[0003] In motor vehicles with an electric drive, which can therefore be described as battery-electric vehicles, the traction battery is constantly under load during operation, causing it to heat up. A cooling system is provided to ensure reliable operation of the drive components at all temperatures.

[0004] The traction battery's cooling system requires energy for its operation, which is generated by the traction battery itself. Therefore, a lower energy requirement for heating or cooling the traction battery directly corresponds to an increase in the energy available for operating the vehicle. In other words, a lower energy requirement for heating or cooling the traction battery results in a greater vehicle range.

[0005] German patent application DE 10 2019 001 391 A1 discloses an electric vehicle with an underfloor traction battery, wherein an adjustable air intake opening is provided in the front area of ​​the electric vehicle by means of an adjustable control flap. The airflow flowing in through the air intake opening is used to cool the underfloor traction battery.

[0006] German patent application DE 10 2016 210 266 A1 describes an electric vehicle with a traction battery located on the underbody. The traction battery is completely separated from the road surface by a base plate to create an air-insulating layer. Air circulation is facilitated by flaps and / or valves, which are located above the base plate and extend along the vertical axis of the electric vehicle.

[0007] From the patent application DE 10 2011 018 553 A1, a motor vehicle with a passenger compartment and a battery is known, wherein the passenger compartment and the battery are fluidically connected to a first, permanently open air inlet opening and the battery is additionally connected to a second air inlet opening controllable by a flap.

[0008] Patent EP 2 199 133 B1 discloses a hybrid vehicle with an underfloor battery, wherein an airflow is directed to the underfloor battery via a box profile body for cooling the underfloor battery, wherein the airflow is adjustable by means of an adjusting valve.

[0009] DE 10 2019 102 781 A1 shows a high-voltage battery for an electric vehicle, with a battery module comprising several interconnected battery cells and a heat sink thermally coupled to the battery module to absorb heat emitted by the battery module.

[0010] In DE 10 2018 211 559 B4 a vehicle with an air conditioning device for the interior air conditioning of electric vehicles is disclosed.

[0011] The object of the present invention is to provide an improved motor vehicle with a traction battery.

[0012] This problem is solved according to the invention with a motor vehicle having a traction battery with the features of claim 1. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the respective dependent claims.

[0013] A motor vehicle according to the invention comprises a traction battery housed within a vehicle body comprising a body shell and an underbody. The traction battery is designed for an electric drive. A cooling system is provided for cooling the electric drive. According to the invention, for cooling the traction battery, which is arranged in a cavity formed between the body shell and the underbody, an underbody element has a passage opening that can be opened or closed by means of a closing element, allowing air to flow into the cavity through the passage opening and circulate around the traction battery for cooling via convection.Simply opening the through-hole allows for easy cooling of the traction battery via convection, as air can flow through the opening above the underbody and thus into the vehicle body where the traction battery is housed. This supplements the cooling of the traction battery by convection, thereby reducing the energy the battery expends on cooling itself.

[0014] Preferably, the closing element is controllable so that cooling can be actively achieved through convection. With the help of the controllable closing element on the underbody, waste heat from the traction battery can be dissipated convectively during driving, thus saving cooling capacity. Naturally, the closing element could also be self-regulating, for example, in the form of a check valve that uses negative pressure to open or close the passage opening; however, reliable cooling, especially when the traction battery is under load, would then not be guaranteed.

[0015] Advantageously, the closing element is designed in the form of a flap, wherein the closing element is in particular designed in the form of a pivotably mounted flap, which is preferably pivotably arranged on the underside.

[0016] To create an air cushion insulation between the traction battery and the body shell and / or underbody, an air gap is formed between the traction battery and the body shell and / or underbody. When the vehicle is stationary, the air between the body shell and / or underbody can thus provide insulation. During driving, the air, particularly when an air gap exists between the underbody and the body shell, can flow around the traction battery, at least along the vertical axis of the vehicle body (top and bottom), thus providing preferential cooling by convection. An insulating effect when stationary reduces the influence of the environment, i.e., cooling or heating via the body shell.

[0017] The through-opening can be positioned upstream or downstream in the direction of travel and / or in an area of ​​the underbody element covered by the traction battery. In other words, it does not necessarily have to be located upstream of the traction battery, i.e., in front of the traction battery in the direction of airflow. However, this is the preferred position for the through-opening, as it allows air to flow directly onto the traction battery against the direction of travel without any additional aids.

[0018] Preferably, the locking element is designed to have a NACA profile so that the aerodynamic performance of the motor vehicle is not, or at least not significantly, affected by the locking element.

[0019] Overall, a motor vehicle with a traction battery has been realized which has an increase in an effectively usable electric range, since part of the necessary cooling power is replaced by the measures described above.

[0020] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figure alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. The single figure shows a general representation of a motor vehicle according to the invention with a traction battery.

[0021] A motor vehicle 1 according to the invention has a traction battery 2, which is configured to drive an electric motor (not shown in detail). The motor vehicle 1 has a body 3, which comprises a body shell 4 and an underbody 5, wherein the underbody 5 at least partially separates the body shell 4 from a road surface 6. A cavity 7 is formed between the body shell 4 and the underbody 5, in which the traction battery 2 is arranged. In the present embodiment, the cavity 7 is formed between a front 8 of the motor vehicle body 3 and a rear 9 of the motor vehicle body 3, in a so-called central area 10 of the motor vehicle body 3. The central area 10 lies within the passenger compartment of the motor vehicle body 3.

[0022] The traction battery 2 is designed to supply energy to the electric motor. It comprises a battery module with a plurality of battery cells and is permanently connected to the vehicle body 3.

[0023] To cool an electric drive 11 comprising the traction battery 2 and the electric motor, a cooling system 12 with a cooling circuit 13 is provided, wherein the cooling circuit 13 can have two independently configured sub-circuits so that the traction battery 2 can be cooled independently of the electric motor and vice versa. The cooling circuit 13 can be routed through the body shell 4 to utilize the body shell 4 as a heat sink.

[0024] According to the invention, the motor vehicle body 3 of the motor vehicle 1, which is designed in the form of an electric vehicle, has a passage opening 15 on an underbody element 14 of the underbody 5, through which air can flow into the cavity 7.

[0025] In the present embodiment, the through-opening 15 is designed to extend along a longitudinal axis 16 of the vehicle body 3 and, viewed in the direction of travel, upstream of the traction battery 2. It could equally be located downstream of the traction battery 2 or in an area of ​​the underbody element 14 covered by the traction battery 2. Air flows through the through-opening 15 into the cavity 7 and can circulate around the traction battery 2 for cooling via convection.

[0026] To control the cooling of the traction battery 2 using the air flowing through the opening 15, the opening 15 can be closed with a closing element 17, preferably in the form of a flap. It could also be designed as a sliding element or a fully closable cover; however, the flap-shaped closing element 17 has the advantage of providing airflow guidance, as can be seen in the figure with the help of the airflow lines 18. Preferably, if the closing element 17 is designed as a flap, it opens towards the body shell 4 and is pivotably attached to the underbody element 14 about a pivot axis 21.

[0027] If the closing element 17 is positioned in a position that completely closes the passage opening 15, the air flows along the underbody 5 between the underbody 5 and the floor 6 without entering the cavity 7. However, if the closing element 17 is positioned in a position that partially or completely opens the passage opening 15, the air can flow through the passage opening 15 into the cavity 7 and flow around the traction battery 2 for heat dissipation.

[0028] The closing element 17 is preferably open during the driving operation of the motor vehicle 1, since in this state of the motor vehicle 1 a preferential flow of air into the cavity 7 can be achieved.

[0029] The air could be released downstream of the traction battery 2 through another opening, not shown in detail, back into an environment 19.

[0030] Furthermore, an air gap 20 formed between the body shell 4 and the traction battery 2, which is designed to preferably allow complete airflow around the traction battery 2, makes it possible to form an air cushion, particularly when the vehicle 1 is stationary, which acts as insulation against the body shell 4. The air gap 20 is also present between the underbody element 14 and the traction battery 2. The insulating effect when stationary reduces the influence of the surrounding environment 19 on cooling or heating via the body shell 4.

[0031] In a further embodiment, not shown in detail, the closing element 17 has an aerodynamic profile in the form of an airfoil profile, in particular in the form of a so-called NACA profile, so that, especially when the passage opening 15 is open, the air resistance of the vehicle body 3 is not negatively affected, or in other words, increased or at least not significantly increased. Reference symbol list 1 motor vehicle 2 traction batteries 3 Motor vehicle body 4 Shell construction 5 Underbody 6. Driving surface 7 Cavity 8 Front 9 Rear 10 Middle range 11 Electric drive 12 Cooling system 13 Cooling circuit 14 Underfloor element 15 Passage opening 16 Longitudinal axis 17 Locking element 18 Airflow line 19 surroundings 20 air gap 21 Swivel axis

Claims

Motor vehicle (1) with a traction battery (2), wherein the traction battery (2) is accommodated in a motor vehicle body (3) comprising a body shell (4) and an underbody (5), and wherein the traction battery (2) is designed for an electric drive (11), and wherein a cooling system (12) is provided for cooling the electric drive (11), characterized in that, for cooling the traction battery (2), which is arranged in a cavity (7) formed between the body shell (4) and the underbody (5), an underbody element (14) of the underbody (5) has a passage opening (15) which can be opened or closed by means of a closing element (17), wherein air can flow into the cavity (7) via the passage opening (15), and can flow around the traction battery (2) for cooling by convection. Motor vehicle (1) according to claim 1 , characterized in that the locking element (17) is controllable. Motor vehicle (1) according to claim 1 or 2, characterized in that the closing element (17) is designed in the form of a flap. Motor vehicle (1) according to 3, characterized in that the closing element (17) is designed in the form of a pivotably mounted flap. Motor vehicle (1) according to claim 3 or 4, characterized in that the locking element (17) is pivotably arranged on the underbody (5). Motor vehicle (1) according to one of the preceding claims, characterized in that an air gap (20) is formed between the traction battery (2) and the body shell (4). Motor vehicle (1) according to one of the preceding claims, characterized in that an air gap (20) is formed between the traction battery (2) and the underbody (5). Motor vehicle (1) according to one of the preceding claims, characterized in that the passage opening (15) is arranged in the direction of travel upstream or downstream and / or in an area of ​​the underbody element (14) covered by the traction battery (2). Motor vehicle (1) according to one of the preceding claims, characterized in that the locking element (17) is designed having a NACA profile.

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