Motor vehicle having a battery temperature-controlled by an ultrasonic generator

Abstract

The invention relates to a motor vehicle, comprising an electric drive motor (10), which is fed by Li-ion cells (16a-16e), and a controller (12), which has a charging circuit (14) with a fast charging mode for the Li-ion cells (16a-16e), the Li-ion cells (16a-16e) being arranged in a battery housing (20). According to the invention, a liquid immersion medium (24) is arranged in the battery housing (20) and at least partially surrounds the Li-ion cells (16a-16e). An ultrasonic generator (38a-38e), which is connected to the electrical controller (12), is arranged in connection with the immersion medium (24). The motor vehicle has a cooling device (32) for the immersion medium (24), and the electrical controller (12) is designed to at least temporarily activate the ultrasonic generator (38a-38e) at least in the fast charging mode. The invention allows quicker and more battery-friendly charging of Li-ion batteries in motor vehicles.

Description

[0001] Mercedes-Benz Group AG

[0002] motor vehicle

[0003] The invention relates to a motor vehicle comprising at least one electric drive motor powered by lithium-ion cells and an electrical control unit that includes a charging circuit with a fast-charging mode for the lithium cells, wherein the lithium cells are arranged in a battery housing. This is the standard configuration of modern electric cars. A critical aspect of using electric cars is recharging the batteries, especially on long journeys. Charging lithium-ion cells takes time, and even fast-charging methods have limitations, particularly considering that fast charging often generates significant heat in the cells, which can negatively impact their lifespan.

[0004] The object of the invention is therefore to create a motor vehicle that can be charged faster and more gently in fast-charging mode.

[0005] This problem is solved by a motor vehicle according to claim 1. Advantageous further developments of the invention are the subject of the dependent claims.

[0006] According to the invention, a liquid immersion medium is arranged in the battery housing, which at least partially surrounds the lithium-ion cells. An ultrasonic generator is arranged in conjunction with the immersion medium and is connected to the electrical control unit or its charging circuit. The vehicle also has a cooling device for the immersion medium, and the electrical control unit is configured to activate the ultrasonic generator, at least temporarily, at least in fast-charging mode.

[0007] The invention offers several advantages. Firstly, it improves both the battery's fast-charging capability and its overall performance because the introduction of ultrasound during fast charging enhances the dynamics of charge transport by the lithium ions within the cells. This is achieved by utilizing a "cavitation effect" generated by the ultrasound in the liquid. This cavitation involves the rapid formation and disintegration of vapor bubbles within the liquid, caused by the oscillating pressure of the ultrasonic elements. The disintegration of these vapor bubbles creates small microcurrents that enhance the energy of the lithium ions in the electrolyte and allow for faster mass transfer. In summary, the dynamics of lithium ion transport, and thus the performance of the lithium-ion cells, are significantly improved.

[0008] By using ultrasound during cell operation, lithium concentration gradients in the electrolyte can be homogenized, thereby improving cell performance, especially at high charging rates and low temperatures. Furthermore, ultrasound can reduce the internal resistance of the cells, which can contribute to higher charging currents. The immersion medium serves both to transmit the ultrasound to the cell and to cool the cells, particularly in fast-charging mode, where significant heat generation can occur. The solution according to the invention thus combines optimal cell cooling with optimal sound transmission. Cell venting paths are not blocked if a cell rupture disc is located in the cell base. Heat conduction paths between the cell and the cooling device are not affected by the invention.

[0009] In an advantageous embodiment of the invention, the electrical control unit is configured to activate the ultrasonic generator and / or the cooling device depending on a temperature sensor connected to the control unit for the immersion medium and / or the lithium-ion cells. This has the advantage that the operation of the ultrasonic generator and the cooling device can be coordinated in such a way as to enable optimal fast-charging operation.

[0010] Furthermore, the ultrasound injection ensures a more homogeneous temperature distribution in the immersion medium, which also has a positive effect on the charging dynamics of the cells.

[0011] Preferably, the electrical control unit is connected to a device for sensing the power output of the lithium-ion cells and is configured to activate the ultrasonic generator depending on the power output. If the electrical control unit detects that a high power output is being drawn from the lithium-ion cells, it can activate the ultrasonic generator to improve the cells' performance and thus enhance power output.

[0012] Preferably, the cooling device is arranged at a different location on the battery housing than the ultrasonic generator. This has the advantage that the ultrasonic generator does not impair the cooling effect of the cooling device, particularly in conjunction with the immersion medium.

[0013] According to an advantageous embodiment of the invention, a cell contacting system, e.g., internal wiring for contacting the Li-ion cells, is provided. This is arranged in the immersion medium, which also cools the connecting leads. This reduces their internal resistance and also positively influences the fast-charging capability.

[0014] Preferably, the immersion medium is oil. This has the advantage that the immersion medium can also be used in electrically conductive sections, such as the cell contacting system, because it is an electrical insulator. Furthermore, this immersion medium provides protection against environmental influences. While the use of water would be more effective in terms of thermal conductivity, it has the disadvantage of being electrically conductive and therefore, for safety reasons, not as suitable for use with battery cells.

[0015] Preferably, the ultrasonic generator is formed by a plurality of ultrasonic elements in contact with the immersion medium. This allows the ultrasound to be introduced more uniformly into the battery housing and thus into the cells over a larger area, resulting in more homogeneous sound transmission and therefore a more consistent improvement in performance across all battery cells. Preferably, the ultrasonic elements are formed by piezoelectric elements. Piezoelectric elements are a proven technology for use as ultrasonic elements, are resistant to higher temperatures, and have a long service life.

[0016] In an advantageous embodiment of the invention, the ultrasonic elements are arranged on the lid and / or the bottom of the battery housing. This allows them to irradiate the cells uniformly from above and / or below with ultrasound, resulting in homogeneous ultrasound distribution. If the ultrasonic elements are arranged only on one side, i.e., on the lid or the bottom, the other side can be used to locate other elements, such as a cooling and / or heating device for the cells or for the immersion medium.

[0017] Preferably, a portion of the lithium-ion cells immersed in the immersion medium is separated from the portion not immersed in the immersion medium by a barrier plate within the battery housing. By positioning this barrier plate at a desired height, the size of the cell immersed in the immersion medium can be determined. The portion of the cells not immersed in the battery housing can then be used for other components, such as wiring, cooling or heating elements, temperature sensors, etc.

[0018] Preferably, the vehicle has a heating device for the immersion medium, and the electrical control unit is configured to activate the heating device based on a temperature sensor for the immersion medium and / or the lithium-ion cells connected to the control unit. In this way, the performance of the lithium-ion cells can be improved even at low temperatures, in which case the cells are heated via the immersion medium and simultaneously exposed to ultrasound. This significantly improves the performance of the lithium-ion cells at high temperatures, at low temperatures, and during fast charging.

[0019] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment 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.

[0020] The invention is described below, for example, in the schematic drawing. In this drawing: Fig. 1 shows a schematic representation of a battery with Li-ion cells of an electrical

[0021] Control unit with charging circuit and a drive motor of a motor vehicle.

[0022] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0023] Fig. 1 shows an electric drive motor 10 of a motor vehicle connected to an electrical control unit 12, which has a charging circuit 14 for the lithium-ion cells 16a to 16e of a battery 18. The battery 18 comprises a battery housing 20 in which the lithium-ion cells 16a to 16e are arranged vertically. A horizontal barrier plate 22 is arranged between the cells 16a to 16e in the battery housing 20. Above the barrier plate 22, the interior of the battery housing around the top of the lithium-ion cells 16a to 16e is flooded with an immersion medium 24, in particular oil. The immersion medium thus surrounds the contacts 26 of the lithium-ion cells 16a to 16e located at the top and a contacting system, such as wiring 28, which connects the cells 16a to 16e to the electrical control unit 12.On the upper part 25 of the battery housing 20, which is permeated by the immersion medium, a temperature sensor 30 for the immersion medium, connected to the electrical control unit 12, a cooling device 32, and a heating device 34 for the immersion medium, also connected to the control unit 12, are arranged. In the cover 36 of the battery housing, ultrasonic elements 38a to 38e in the form of piezoelectric elements are arranged above each of the Li-ion cells 16a to 16e. These elements radiate into the immersion medium 24 and, via the immersion medium, onto the Li-ion cells 16a to 16e. A fast-charging connector 40 is also connected to the electrical control unit 12, i.e., to its charging circuit 14.

[0024] Any activity related to charging or fast-charging the battery 18 is controlled by the vehicle's electrical control unit 12 or by the charging circuit 14. The individual ultrasonic elements 38a to 38e form an ultrasonic generator, which emits the ultrasound uniformly over the entire surface of the battery. It is understood that the battery 20 extends beyond the plane of the drawing. The lithium-ion cells are therefore arranged three-dimensionally in rows and columns within the battery housing 20. When the fast-charging plug 40 is connected to a fast-charging station and the charging process begins, the charging current, which is introduced into the lithium-ion cells 16a to 16e via the cell contacting system 28, is controlled by the charging circuit.To improve the dynamics, especially the ion transfer of the cells, the electrical control 14 activates the ultrasound generator, i.e. the ultrasound elements 38a to 38e, in order to increase the efficiency of the cells during charging by introducing ultrasound.

[0025] Similarly, the ultrasonic generator 38a to 38e is activated when a very high power output is required from the Li-ion cells 16a to 16e to the motor 10. By monitoring the temperature of both the immersion medium with the temperature sensor 30 and the temperature of the Li-ion cells using a second temperature sensor 42 in conjunction with the cooling device 32 and the heating device 34, the electrical control unit, in conjunction with its charging circuit 14, can set an optimal temperature in the immersion medium for operation, in order to operate the cells 16a to 16e within an optimal temperature range and thus increase their efficiency and service life.

[0026] The use of the ultrasound cells 38a to 38e arranged in the immersion medium according to the invention thus considerably improves both the charging behavior and the power output of the cells.

[0027] The invention is not limited to the described embodiment, but can instead be varied within the scope of protection of the attached claims.

[0028] Reference symbol list

[0029] 10. Motor vehicle drive motor

[0030] 12. Electrical control of the motor vehicle

[0031] 14 Charging circuit of the electrical control

[0032] 16a-d Li-ion cells

[0033] 18 battery cases

[0034] 20 Wall of the battery housing

[0035] 22 Barrier plate between the part of the battery housing permeated by the immersion medium and the part not permeated by it

[0036] 24 Immersion medium

[0037] 25 Part of the battery housing permeated by the immersion medium

[0038] 26 contacts on the head of the Li-ion cells

[0039] TI: Part of the battery casing not penetrated by the immersion medium

[0040] 28 Contacting system / wiring of the Li-ion cells

[0041] 30 Temperature sensor for the immersion medium

[0042] 32 Cooling device for the immersion medium

[0043] 34 Heating device for the immersion medium

[0044] 36. Battery housing cover to which the ultrasonic elements are attached

[0045] 38a-d the ultrasonic elements forming the ultrasonic generator

[0046] 40 fast charging plugs for quick charging of Li-ion cells

[0047] 42 optional temperature sensor on the Li-ion cells

Claims

Mercedes-Benz Group AG Patent claims 1. Motor vehicle comprising at least one electric drive motor (10) powered by Li-ion cells (16a - 16e) and an electrical control unit (12) having a charging circuit (14) with a fast-charging mode for the Li-ion cells (16a - 16e), wherein the Li-ion cells (16a - 16e) are arranged in a battery housing (20), wherein a liquid immersion medium (24) is arranged in the battery housing (20) which at least partially surrounds the Li-ion cells (16a - 16e), that an ultrasonic generator (38a - 38e) is arranged in conjunction with the immersion medium (24) and is connected to the electrical control unit (12), that the motor vehicle has a cooling device (32) for the immersion medium (24), and that the electrical control unit (12) is configured to activate the ultrasonic generator (38a - 38e) at least temporarily, at least in the fast-charging mode, thereby characterizedthat the motor vehicle has a heating device (34) for the immersion medium (24), and that the electrical control (12) is configured to activate the heating device (34) depending on a temperature sensor (30) for the immersion medium (24) and / or the Li-ion cells (16a - 16e) connected to the control (12).

2. Motor vehicle according to claim 1, characterized in that the electrical control is configured to activate the ultrasonic generator (38a - 38e) and / or the cooling device (32) depending on a temperature sensor connected to the control (12) for the immersion medium (24) and / or the Li-ion cells (16a - 16e).

3. Motor vehicle according to claim 1 or 1, characterized in that the electrical control (12) is connected to a device for detecting the power delivered by the Li-ion cells (16a - 16e) and is configured to activate the ultrasonic generator (38a - 38e) depending on the power.

4. Motor vehicle according to one of the preceding claims, characterized in that the cooling device (32) is arranged at a different location on the battery housing (20) than the ultrasonic generator (38a - 38e).

5. Motor vehicle according to one of the preceding claims, characterized in that a cell contacting system (28) for the Li-ion cells (16a - 16e) is arranged in the immersion medium (24).

6. Motor vehicle according to one of the preceding claims, characterized in that the ultrasonic generator (38a - 38e) is formed by a plurality of ultrasonic elements which are in contact with the immersion medium (24).

7. Motor vehicle claim 6, characterized in that the ultrasonic elements (38a - 38e) are formed by piezoelectric elements.

8. Motor vehicle according to claim 5 or 6, characterized in that the ultrasonic elements (38a - 38e) are arranged on the lid (36) and / or bottom of the battery housing (20).

9. Motor vehicle according to one of the preceding claims, characterized in that in the battery housing (20) a part (25) wetted by the immersion medium (24) is separated from a part (27) not wetted by the immersion medium (24) by a barrier plate (22).

Images