COOLING DEVICE FOR ELECTRIC OR HYBRID AUTOMOBILE BATTERIES

Abstract

The invention relates to a battery (130) for an electric or hybrid vehicle. The battery (130) comprises an air duct (110) and a battery cell frame (120). The air duct (110) has a heat exchange surface (112) in contact with the battery cell frame (120). The air duct has an air inlet having a first section (110A) and an air outlet having a second section (110B). The air duct (110) has a reduced cross-section configured to accelerate an airflow (F) between the first section (110A) and the second section (110B). In addition, the air duct may also have projections (113) promoting the creation of turbulence in the airflow (F). By these means, the airflow (F) efficiently cools the battery (130). Figure 1

Description

Title of the invention: COOLING DEVICE FOR BATTERIES OF ELECTRIC OR HYBRID AUTOMOBILES

[0001] The invention relates to electric vehicles, that is to say, those equipped with at least one battery for storing electrical energy intended for their propulsion. This includes vehicles with a single means of electric propulsion, as well as hybrid vehicles incorporating at least one mode of electric propulsion.

[0002] It is known from the prior art that batteries heat up during vehicle operation. Thus, patent application CN114824564 describes a cooling device for a battery tray of an electric motor vehicle. The battery tray comprises rows of batteries separated by gaps. The device includes an air injection reservoir with an air inlet and an air outlet. The air outlet has a vent open to the battery tray. An airflow is introduced into the air inlet, circulates through the air injection reservoir, and exits through the vent. In this way, the air injection reservoir injects the airflow into the battery tray. In particular, the airflow circulates between the gaps in the batteries. In this way, the airflow cools the battery tray by thermal convection. Furthermore, a surface of the air injection reservoir is inclined.The inclined surface accelerates the airflow. This allows the airflow to cool the battery tray more effectively through thermal convection. However, the airflow is accelerated in the air injection reservoir, not in the battery tray. Therefore, the airflow slows down as it travels between the injection reservoir and the battery tray. Furthermore, the outgoing airflow is limited by the air outlet grille. In addition, the airflow passes through the gaps between the batteries in the battery tray, further slowing it. For these reasons, the airflow cools the battery tray less effectively.

[0003] The objective of the present invention is to remedy these drawbacks and improve the cooling performance of the electric vehicle battery.

[0004] To achieve this objective, the invention proposes an electric or hybrid vehicle battery, the battery having a longitudinal axis, the battery comprising an air duct and a battery cell chassis, the air duct having an air inlet having a first section, the air duct having an air outlet having a second section, the air duct being configured to circulate an airflow from the first section to the second section, the air duct having a exchange surface fixed to the battery cell chassis, the surface of the first section is larger than the surface of the second section.

[0005] This accelerates the airflow. Consequently, the airflow cools the heat exchange surface, and by extension, the battery, more effectively. Furthermore, this method of airflow cools the battery more evenly. As a result, the battery benefits from improved performance and durability.

[0006] Advantageously, the air duct comprises a wall opposite the exchange surface, the wall having an angle between 20 and 60 degrees with respect to the longitudinal axis.

[0007] This provides a simple air duct geometry that is easy to manufacture and assemble. Furthermore, this angle allows for greater control over the acceleration of the airflow. Thus, the airflow efficiently cools the battery.

[0008] Advantageously, the surface of the first section has a surface area 2 to 5 times larger than the surface area of ​​the second section.

[0009] The reduced cross-section also allows for better control of the airflow acceleration. Thus, the airflow efficiently cools the battery, resulting in improved battery performance and durability.

[0010] Advantageously, the air duct has projections.

[0011] The protrusions promote the creation of turbulence in the airflow within the duct. This turbulence improves the heat dissipation capacity of the airflow. Thus, the airflow cools the battery even more effectively. Furthermore, the length of the protrusions can be determined so that their overall length does not exceed half the cross-section of the air duct, thereby preventing excessively long protrusions.

[0012] Advantageously, the projections are rows of flat-shaped fins.

[0013] The projections arranged in this way allow the airflow to be directed in a more controlled manner. Furthermore, the fins of this shape significantly increase the surface area in contact with the airflow. Thus, heat transfer is greater. As a result, the airflow cools the battery more effectively.

[0014] Advantageously, the projections have an angle of 20 to 45 degrees with respect to the longitudinal axis.

[0015] The inclination of the projections allows the turbulence to be directed in a more controlled manner, thus improving the heat dissipation capabilities of the airflow.

[0016] Advantageously, the projections are arranged downstream of the airflow.

[0017] This maximizes the effect of the turbulence created by the protrusions, making heat exchange even more efficient, and allowing the heat from the battery to be dissipated effectively.

[0018] Advantageously, the battery cell chassis comprises a first stage and a second stage, the space between the first stage and the second stage defining an internal passage comprising the air duct, the battery cell chassis having a first longitudinal end and a second longitudinal end, the first longitudinal end comprising the first section and the second longitudinal end comprising the second section, the exchange surface being fixed to the first stage.

[0019] Thus, the air duct passes inside the battery. This allows for more even cooling of the battery. Indeed, with this configuration, the formation of hot spots inside the battery cell chassis is more easily avoided.

[0020] Advantageously, the battery includes an additional duct, the internal passage comprising the additional duct, the additional air duct having an air inlet having a first additional section, the additional air duct having an air outlet having a second additional section, the additional air duct being configured to circulate the airflow from the first additional section to the second additional section, the first longitudinal end comprising the first additional section and the second longitudinal end comprising the second additional section, the additional air duct comprising an additional exchange surface fixed to the second stage.

[0021] This allows for the addition of extra exchange surfaces with the battery cell chassis. In this way, battery cooling is more efficient.

[0022] The invention also relates to an electric or hybrid vehicle comprising a battery as defined above.

[0023] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: - [Fig.1] schematically illustrates a longitudinal cross-sectional view of a battery, according to a first embodiment of the invention; - [Fig.2] schematically illustrates a longitudinal cross-sectional view of a battery comprising a battery cell chassis through which two air ducts pass, according to a second embodiment of the invention.

[0024] Figure 1 illustrates a battery 130 for an electric or hybrid vehicle comprising an air duct 110 and a battery cell frame 120 according to a first embodiment of the invention. The battery 120 has a longitudinal axis X. The air duct 110 is attached to the battery cell frame 120. The air duct 110 is affixed to the battery cell frame 120. Thus, the air duct 110 has an exchange surface 112 defining the surface where the air duct 110 and the frame of Battery cells 120 are in contact. Furthermore, the exchange surface 112 has a flat shape contained in a longitudinal plane parallel to the longitudinal axis X.

[0025] The air duct 110 is configured to circulate an airflow F. The airflow F cools the exchange surface 112 by thermal convection. By extension, the airflow F cools the battery 130.

[0026] The air duct 110 extends between a first section 110A and a second section 110B. The first section 110A connects to an air passage. In this way, the air passage injects a flow of air into the air duct. The second section 110B connects to an air exhaust. In this way, the air exhaust discharges the airflow outside the vehicle. The first section 110A is an air inlet. The second section 110B is an air outlet. Thus, the airflow F can circulate in the air duct 110. In particular, the airflow F flows from the first section 110A to the second section 110B.

[0027] In the following, the terms "upstream" and "downstream" are defined with respect to the direction of the airflow F. Thus, upstream refers to the side from which the airflow F originates, i.e., the side of the air passage. Conversely, downstream refers to the side toward which the airflow F is directed, i.e., the side of the air exhaust. Thus, the airflow F flows from upstream to downstream of the air duct 110.

[0028] The first section 110A and the second section 110B are perpendicular to the longitudinal axis X. According to one variant, the first section or the second section may be arranged obliquely to the longitudinal axis X. In this case, the first section 110A or the second section 110B forms an angle with respect to the longitudinal axis of between 0 degrees and 90 degrees excluded.

[0029] The battery cell frame 120 extends along the longitudinal axis X. The battery cell frame 120 comprises a first longitudinal end 120A arranged upstream and a second longitudinal end 120B arranged downstream. The first longitudinal end 120A lies in a first plane perpendicular to the longitudinal axis X. The second longitudinal end 120B lies in a second plane perpendicular to the longitudinal axis X. The first section 110A is arranged in the first plane. The second section 110B is arranged in the second plane. Thus, the heat exchange surface 112 extends along the entire length of the battery cell frame 120 along the longitudinal axis X. Consequently, the ratio between the heat exchange surface 112 and the length of the air duct is maximized. In this way, the airflow F efficiently cools the 130 battery relative to the size of the 130 battery.

[0030] According to one embodiment, the first section 110A is arranged in a third plane perpendicular to the longitudinal axis X. The third plane is located further downstream of the longitudinal axis X than the first plane. According to another embodiment, the first section 110A is arranged in a fourth plane perpendicular to the longitudinal axis X. The fourth plane is located further upstream of the longitudinal axis X. In both cases, the battery cell chassis 120 has a portion that is not in contact with the air duct 110. This further minimizes the size of the air duct 110.

[0031] The battery cell frame 120 comprises battery cells. Furthermore, the battery cells 130 are separated by gaps. Preferably, the battery cell frame is made of aluminum. In addition, the heat exchange surface 112 hermetically seals the battery cell frame 120. In this way, the airflow F does not pass through the gaps. Consequently, this avoids the need to filter or dry the airflow F.

[0032] Furthermore, the cells of the battery 130 are immersed in a dielectric fluid. The dielectric fluid helps to homogenize the temperature of the cells of the battery 130. In particular, this prevents temperature differences between the cells of the battery 130, which lead to uneven performance and premature aging of the cells of the battery 130. Moreover, the dielectric fluid reduces the risk of short circuits between the cells of the battery 130. Thus, the dielectric fluid adds additional safety to the battery 130 and improves its durability and performance.

[0033] As seen previously, during vehicle operation, the battery cells generate a certain amount of heat. In particular, some of the generated heat is received by the heat exchange surface 112. As it flows through the air duct 110, the airflow F extracts the generated heat by convection from the heat exchange surface 112.

[0034] The airflow F cools the heat exchange surface 112. By extension, the dielectric fluid is cooled. The dielectric fluid homogenizes the cooling within the battery cell frame 120. In this way, the battery cell frame 120 and, consequently, the battery 130 are cooled. Thus, the heat exchange surface 112 defines a heat exchange surface between the airflow F and the battery cell frame 120.

[0035] Due to heat exchange, the airflow F heats up along the longitudinal axis X. The heated airflow F is then exhausted through the air outlet. Thus, the amount of heat generated is dispersed outside the battery 130.

[0036] The first section 110A and the second section 110B have a first surface and a second surface, respectively. The first surface is twice as large as the second section. Thus, the air duct 110 necessarily has at least one reduction in cross-section between the first section 110A and the second section 110B. The air duct has a wall 111 forming, in a cross-sectional view, a first angle with respect to the longitudinal axis X. The wall has a The wall 111 is flat. It extends between the first section 110A and the second section 110B. Furthermore, the wall is located opposite the heat exchange surface 112. In an axial view defined by the longitudinal axis X and a plane transverse to the longitudinal axis X, the wall 111 forms a second angle with respect to the longitudinal plane. The first angle is approximately 30 degrees, and the second angle is approximately 0 degrees. The first angle allows for better control of the temperature differential between the upstream and downstream sides of the airflow. The second angle allows for improved control over the parts of the battery requiring more cooling.

[0037] According to one embodiment, the first angle is between 20 degrees and 60 degrees, and the second angle is substantially 0 degrees. According to another embodiment, the reduction in cross-section has a concave shape in cross-section and the second angle is 0 degrees. The concave shape allows for better control of the acceleration of the airflow in the air duct 110.

[0038] Thanks to the reduced cross-section, the airflow F reaches a higher velocity downstream than upstream. As a result, the temperature of the airflow F is more uniform throughout the air passage. Consequently, the airflow F cools the battery 130 more evenly. In general, the battery 130 is subjected to less thermal stress. As a result, the battery benefits from a longer service life and increased energy efficiency.

[0039] Also, thanks to the reduced cross-section, the airflow F cools the battery 130 more efficiently, because the heat transfer downstream of the exchange surface is greater. Thus, the amount of heat generated and extracted from the battery 130 is greater. Of course, other variations can be considered in which the first surface is three, four, or even five times larger than the second surface. In this case, the two aforementioned effects of the reduced cross-section will be even more pronounced.

[0040] In one embodiment, the airflow F exhibits laminar flow. In another embodiment, the airflow F exhibits turbulent flow. Turbulent flow allows for higher heat transfer compared to laminar flow. Thus, the turbulent flow of the airflow F cools the battery 130 more efficiently.

[0041] The air duct 110 may have projections 113. The projections may be rows of fins. The projections 113 are arranged downstream of the wall 111. In cross-section, the projections form a projection inclination angle with respect to the longitudinal axis X. The projection inclination angle is between 20 and 45 degrees with respect to the longitudinal axis X. The rows of fins have a length between 5 cm and 15 cm. According to one embodiment, the projections 113 are arranged on the wall 111. The projections 113 disrupt the flow of the airflow F. Thus, the projections promote the creation of turbulence in the airflow F. As a result, the projections contribute to improving the cooling of the battery 130 by the airflow F.

[0042] According to one embodiment, the heat exchange surface 112 can be envisaged to have projections parallel to the longitudinal axis X. The fins increase the heat exchange surface 112 and do not obstruct the airflow F. Thus, the airflow F cools the battery 130 more efficiently.

[0043] In the second embodiment shown in [Fig. 2], the battery cell chassis 220 comprises a first stage 220' and a second stage 220”. The battery 230 comprises a first air duct 210' and a second air duct 210”. The first air duct 210' and the second air duct 210” pass through the battery 230. The first air duct 210' and the second air duct 210” have, respectively, an air inlet having a first section 210A', 210A” and an air outlet having a second section 210B', 210B”. Thus, the first longitudinal end 220A', 220A” and the second longitudinal end 220B', 220B” respectively comprise the first section 210A', 210A” and the second section 210B', 210B”. In this way, the first air duct 210' has a first exchange surface 212' in contact with the first stage 220'.The second air duct 210” has a second heat exchange surface 212” in contact with the second stage 220”. In this way, the battery 230 has additional heat exchange surfaces. Consequently, the battery cooling is more efficient.

[0044] According to an unillustrated embodiment, an air duct passes through the battery cell frame. Thus, the first longitudinal end comprises the first section. Similarly, the second longitudinal end comprises the second section. The heat exchange surface can be in contact with either the first or second stage. The heat exchange surface is a thermal exchange surface between the air duct and the battery cell frame. In this way, the space between the first and second stages of the battery is minimized.

[0045] In a third, unillustrated embodiment, a first air duct and a second air duct may be considered passing through the battery cell frame, as seen in the second embodiment. In this case, the first and second air ducts share a first exchange surface with the first stage and a second exchange surface with the second stage of the battery cell frame, respectively. In addition, a third air duct may be attached to the first stage. Consequently, the third air duct shares a third exchange surface with the first stage of the battery frame. In this way, the available exchange surfaces with the battery. Thus, the airflow F cools the battery even more effectively. In one variant, the third air duct can of course be attached to the second stage of the battery chassis.

Claims

Demands

1. Battery (130, 230) of an electric or hybrid vehicle, the battery (130, 230) having a longitudinal axis (X), the battery (130, 230) comprising an air duct (110, 210', 210”) and a battery cell frame (120, 220), the air duct (110, 210', 210”) having an air inlet having a first section (110A, 210A', 210A”), the air duct (110, 210', 210”) having an air outlet having a second section (110B, 210B', 210B”), the air duct (110, 210', 210”) being configured to circulate an airflow (F) from the first section (110A, 210A', 210A”) to the second section (110B, 21 OB', 210B”), the air duct (110, 210', 210”) having an exchange surface (112, 212', 212”) fixed to the battery cell chassis (120, 220), the battery (130, 230) being characterized in that the surface of the first section (110A, 210A', 210A”) is larger than the surface of the second section (110B, 210B', 210B”).

2. Battery (130, 230) according to claim 1, characterized in that the air duct (110, 210', 210”) has a wall (111, 211', 211”) opposite the exchange surface (112, 212', 212”), the wall (111, 211', 211”) having an angle (a) between 20 and 60 degrees with respect to the longitudinal axis (X).

3. Battery (130, 230) according to any one of claims 1 to 2, characterized in that the surface of the first section (110A, 210A', 210A”) has a surface 2 to 5 times larger than the surface of the second section (110B, 21 OB', 210B”).

4. Battery (130, 230) according to any one of claims 1 to 3, characterized in that the air duct (110, 210', 210”) has projections (113, 213', 213”).

5. Battery (130, 230) according to claim 4, characterized in that the projections (113, 213', 213”) are rows of flat-shaped fins.

6. Battery (130, 230) according to claim 5, characterized in that the projections (113, 213', 213”) have an angle (|3) of 20 to 45 degrees with respect to the longitudinal axis (X).

7. Battery (130, 230) according to any one of claims 4 to 6, characterized in that the projections (113, 213', 213”) are arranged downstream of the airflow (F).

8. Battery (230) according to any one of claims 1 to 7, characterized in that the battery cell frame (220) comprises a first stage (220') and a second stage (220”), the space between the first stage (220') and the second stage (220”) defining an internal passage comprising the air duct (210'), the battery cell frame (220) having a first longitudinal end (220A', 220A”) and a second longitudinal end (220B', 220B”), the first longitudinal end (220A') comprising the first section (210A') and the second longitudinal end (220B') comprising the second section (210B'), the exchange surface (212') being fixed to the first stage (220').

9. Battery (230) according to claim 8, characterized in that the battery (230) comprises an additional duct (210”), the internal passage comprising the additional duct (210”), the additional air duct (210”) comprising an air inlet having a first additional section (210A”), the additional air duct (210”) comprising an air outlet having a second additional section (210B”), the additional air duct (210”) being configured to circulate the airflow (F) from the first additional section (210A”) to the second additional section (210B”), the first longitudinal end (220A”) comprising the first additional section (210A”) and the second longitudinal end (220B”) comprising the second additional section (210B”), the additional air duct (210”) comprising an additional exchange surface (212”) fixed to the second stage (220”).

10. Electric or hybrid vehicle comprising an electric vehicle battery (130, 230) according to any one of claims 1 to 9.

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