Electric vehicle battery

Abstract

Battery of an electric vehicle, comprising at least one battery cell (28), a battery housing (18) which defines an interior housing space (19) in which the battery cell (28) is arranged, and a water detection unit (30) for detecting a water accumulation in the interior housing space (19), wherein the water detection unit (30) comprises a water sensor (321, 322, 323, 324) arranged in the interior housing space (19) and an evaluation unit (34), wherein the water sensor (321, 322, 323, 324) and the evaluation unit (34) are designed such that a water accumulation is detected by means of a change in electrical conductivity, wherein an enrichment unit (44) is provided which is designed to enrich the gas within the interior housing space (19) with electrically conductive particles, wherein the electrically conductive particles are soluble in the water accumulation.

Description

[0001] The invention relates to a battery of an electric vehicle, comprising at least one battery cell, a battery housing which defines an interior housing space in which the battery cell is arranged, and a water detection unit for detecting a water accumulation in the interior housing space, wherein the water detection unit comprises a water sensor arranged in the interior housing space and an evaluation unit, wherein the water sensor and the evaluation unit are designed such that a water accumulation is detected by means of a change in electrical conductivity.

[0002] Such batteries are generally known from the prior art and are used in particular as traction batteries for electric vehicles. Due to the sensitive internal battery cells, the battery must be fluid-tight from the external environment in its final assembled state. If water accumulates in the battery during subsequent normal operation or during assembly, there is a risk of battery failure, especially a short circuit. To detect such a failure, a water sensor connected to a control unit can be installed inside the battery. If a predefined threshold is exceeded, water accumulation in the battery is detected, and appropriate measures are initiated accordingly.The water sensor can be designed, for example, to measure electrical conductivity, allowing the evaluation unit to detect a fault based on this measurement. In particular, an increase in electrical conductivity can indicate water accumulation, as water, which typically contains dissolved ions or conductive particles such as magnesium, calcium, chlorine, nitrogen, and sulfur salts, has a higher electrical conductivity than gas, especially air. Resistance is the inverse of electrical conductivity, so the water sensor can also be designed as a resistance sensor. This type of sensor also functions based on the measurement of electrical conductivity.

[0003] The problem is that condensation can cause water to accumulate inside the housing. Because condensation contains relatively few electrically conductive substances or particles, the electrical conductivity does not change significantly due to the condensation, or at least not enough for the water sensor to reliably detect the accumulation of water inside the housing. However, such condensation can still lead to malfunctions at a later time.

[0004] From CN 2 17 788 508 U and CN 1 14 335 777 A, a battery is known which has a dehumidification device and a humidity sensor, wherein the dehumidification device contains, for example, calcium chloride as a water-absorbing material.

[0005] Furthermore, DE 10 2017 004 296 A1 discloses a battery with a sensor device which has a layer designed to receive a liquid and an electrical conductor connected to a measuring device of the sensor device, wherein the measuring device is designed to detect a change in the electrical resistance of the layer depending on the presence of liquid in the layer.

[0006] The object of the invention is to provide a battery in which water accumulation in the battery can be reliably detected.

[0007] The problem is solved by the features of claim 1.

[0008] According to the invention, an enrichment unit is provided which is designed to enrich the gas within the housing interior with electrically conductive particles, wherein the electrically conductive particles are soluble in the water collection. The electrically conductive particles are formed, for example, by magnesium, calcium, chlorine, nitrogen, and sulfur salts.

[0009] The electrically conductive particles enrich the gas or air inside the housing. These particles settle at the bottom of the housing and dissolve in any condensation that may be present or formed, thus increasing the electrical conductivity of the condensation. This increased electrical conductivity allows the water detection unit to detect any accumulation of water or condensation. Based on this detection, appropriate measures, such as a warning message or battery shutdown, can be initiated. If no condensation is present, the concentration of electrically conductive particles in the gas or air is so low that the electrical conductivity is not increased sufficiently to trigger a false water detection signal.

[0010] This allows for the reliable detection of water accumulation in the battery. In particular, water accumulation caused by condensation can also be reliably detected.

[0011] Preferably, the water sensor is located at the lowest point of the housing interior. Water collects at this lowest point due to gravity. By positioning the water sensor at this lowest point, water accumulation can be detected at a relatively early stage. The lowest point of the housing interior is, in particular, the bottom surface of the battery housing.

[0012] In a preferred embodiment, a cooling unit is arranged on a housing wall forming the base surface, thereby deliberately causing condensation on the base surface. The water sensor is located directly on the base surface.

[0013] In a preferred embodiment, the water detection unit has several water sensors distributed across a base area of ​​the housing interior. This allows water accumulation to be detected across the entire width and depth of the housing interior.

[0014] Preferably, a pressure equalization unit is arranged on a housing wall of the battery housing, and the enrichment unit has an enrichment element. The enrichment element is arranged in the pressure equalization unit such that the air flowing into the housing interior via the pressure equalization unit is enriched with electrically conductive particles. A pressure equalization unit essentially serves to equalize the pressure between the external environment and the housing interior. Air flows from the external environment into the housing interior and from the housing interior back into the external environment. The enrichment element is designed to contain electrically conductive particles, i.e., it stores the electrically conductive particles that are carried into the housing interior by the air flowing from the external environment into the housing interior.The electrically conductive particles, carried along by the airflow, settle on a surface inside the housing. This causes the particles to dissolve in any condensation that may be present, thereby increasing the electrical conductivity of that condensation. This increased electrical conductivity allows the water detection unit to detect any accumulation of water or condensation. Alternatively, the enrichment unit can include an enrichment module located inside the housing. In this case, the electrically conductive particles are carried along, for example, by an airflow circulating within the housing.

[0015] An embodiment of the invention is explained in more detail with reference to the drawing. Fig. Figure 1 schematically shows a battery in longitudinal section.

[0016] Fig.Figure 1 shows a battery 10 of an electric vehicle, which is designed in particular as a traction battery and serves to supply an electric traction machine of the electric vehicle with electrical energy.

[0017] The battery 10 comprises a battery housing 19, which has several side housing walls 22, 24, a top housing wall 20, and a bottom housing wall 26. The housing walls 20, 22, 24, 26 define an interior housing space 19, which, in the fully assembled state of the battery 10, is essentially fluid-tight and separated from the external environment. A cooling plate or cooling unit 60 is arranged on the bottom housing wall 26, by which the battery 10 is cooled during operation.

[0018] A pressure equalization unit 40 is arranged on the housing wall 24, which has a gas-permeable and water-impermeable membrane 42 through which pressure equalization takes place between the outside environment and the housing interior 19. This prevents, in particular, overpressure in the housing interior 19.

[0019] The battery 10 also comprises several battery cells 28, which are arranged in the interior of the housing 19. The battery cells 28 and the electrical busbars connecting the battery cells 28 (not shown) are designed such that if water accumulates in the interior of the housing 19, which may occur during operation or assembly, there is a risk of a short circuit and thus a failure.

[0020] To reliably detect such water accumulation in the housing interior 19, the battery 10 includes a water detection unit 30. The water detection unit 30 comprises several water sensors 321, 322, 323, 324 and an evaluation unit 34. The water sensors 321, 322, 323, 324 are arranged on one side of the battery cells 28 facing the housing wall 26 and distributed over the entire depth and width of the housing interior 19. The water sensors 321, 322, 323, 324 are designed as resistance sensors and are connected to the evaluation unit 34 via a signal. If a change in the electrical conductivity is detected based on the sensor signals of at least one of the water sensors 321, 322, 323, 324, water accumulation is inferred.

[0021] The problem is that, due to the lack of or greatly reduced electrically conductive substances or particles in the condensate, a water accumulation in the interior of the housing 19 does not result in a sufficiently high change in electrical conductivity despite the condensate accumulation, so that a condensate accumulation cannot be reliably detected.

[0022] To reliably detect water accumulation due to condensation, an enrichment unit 44 is provided, which includes an enrichment element 441. The enrichment element 441 is integrated into the pressure equalization unit 40 in such a way that, in particular, an airflow flowing into the housing interior 19 carries electrically conductive particles along with it from the enrichment element 441, thereby enriching the airflow with these electrically conductive particles. The entrained particles settle on the bottom surface of the housing interior 19 or on the housing wall 26, causing them to dissolve in any condensation that may be present or formed. This increases the electrical conductivity of the accumulated condensation to such an extent that water accumulation or condensation can be reliably detected by the water detection unit 30.Based on this, appropriate measures, such as a warning message or the shutdown of battery 10, can be initiated. Alternatively, the enrichment unit can include an enrichment module 442, which is arranged in the interior of the housing 19 and enriches the air in the interior of the housing 19 with electrically conductive particles.

Claims

[1] Battery of an electric vehicle, with at least one battery cell (28), a battery housing (18) which defines an interior housing space (19) in which the battery cell (28) is arranged, and a water detection unit (30) for detecting a water accumulation in the housing interior (19), wherein the water detection unit (30) comprises a water sensor (321, 322, 323, 324) arranged in the housing interior (19) and an evaluation unit (34), wherein the water sensor (321, 322, 323, 324) and the evaluation unit (34) are designed such that a water accumulation is detected by means of a change in electrical conductivity, characterized by , that an enrichment unit (44) is provided which is designed to enrich the gas inside the housing interior (19) with electrically conductive particles, wherein the electrically conductive particles are soluble in the water collection, such that the electrical conductivity of the water collection is increased by electrically conductive particles and the electrical conductivity of the water collection is detected by the water sensor (321, 322, 323, 324). [2] Battery according to claim 1, characterized by , that the water sensor (321, 322, 323, 324) is located at the lowest point of the housing interior (19). [3] Battery according to claim 1 or 2, characterized by , that the water detection unit (30) has several water sensors (321, 322, 323, 324) which are distributed around a bottom area of ​​the housing interior (19). [4] Battery according to any one of the preceding claims, characterized by, that a cooling unit (60) is arranged on a housing wall (26) forming the bottom surface. [5] Battery according to any one of the preceding claims, characterized by , that a pressure equalization unit (40) is arranged on a housing wall (24) of the battery housing (18) and the enrichment unit (44) has an enrichment element (441), wherein the enrichment element (441) is arranged in the pressure equalization unit (40) such that the air flowing into the housing interior (19) via the pressure equalization unit (40) is enriched with the electrically conductive particles. [6] Battery according to any one of claims 1 to 4, characterized by , that the enrichment unit (40) has an enrichment module (442) which is arranged inside the housing interior (19).

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