Power battery unit, battery pack comprising power battery unit and working machine

Abstract

The disclosure relates to a power battery unit. The power battery unit (100) comprises a housing (10), and at least two electric cores (3) accommodated in the housing. The power battery unit further comprises at least one heat-conducting element (4) arranged between two adjacent electric cores (3). The heat-conducting element comprises a portion in contact with the surfaces, facing each other, of the two adjacent electric cores, and also a portion in contact with the housing (10). The disclosure also relates to a battery pack comprising the power battery unit and a working machine comprising the battery pack.

Description

[0001]Description POWER BATTERY UNIT, BATTERY PACK COMPRISING POWER BATTERY UNIT AND WORKING MACHINE Technical Field The disclosure relates to a power battery, in particular thermal management thereof. Background A power battery is an important component of an electric vehicle, and its performance directly determines the power, safety and economical efficiency of the vehicle. The charging and discharging efficiency as well as the service life of a power battery are highly relevant with the temperature. Too high or too low temperature directly affects the efficiency, service life and safety of a power battery unit. Take the lithium-ion power battery as an example, the change of temperature will cause the change of electrochemical performance, thus affecting the service performance and life of the battery. With the increase of temperature, the electrochemical reaction rate increases, which intensifies battery capacity attenuation. Also, low temperature environment will result in battery performance attenuation, the migration ability of lithium ions in active materials of the electrode will be weakened, and the charge / discharge capacity will decrease rapidly. In addition, too high or too low temperature will accelerate battery aging and impact battery life. Especially in the case of charging / discharging at high rates, the temperature has a more significant effect on the battery life. Therefore, battery thermal management is one of the key technologies for developing high-performance power battery systems. A power battery can be constructed in the form of the battery pack (or battery package), which can comprise a plurality of battery units (or battery modules), and each battery unit comprises a battery unit housing and at least one electric core packaged in the battery unit housing. In the current structure of power battery unit, the heat generated by the electric core will be transferred to the housing of the power battery unit, and then to the heat dissipation device for the batteries (for example, the heat dissipation plate shared by a plurality of power battery units located outside the power battery unit). However, the current structure does not allow the electric core to work at a uniform temperature quickly. In addition, in a low temperature state, it is impossible to efficiently heat the power battery unit to the economical working temperature. Therefore, there is a need for an improved power battery unit structure. Summary The concept of the disclosure is based on the fact that electric cores will generate heat during the working process, and the inventors found that when more than one electric core is packaged in the same battery unit housing, the heat will generally concentrate in the middle portion of the electric cores, especially in a central portion between two adjacent electric cores. Therefore, the disclosure proposes improved thermal management measures. According to one aspect of the disclosure, there is provided a power battery unit, which comprises a housing and at least two electric cores accommodated inside the housing. The power battery unit further comprises at least one heat-conducting element arranged between two adjacent electric cores, wherein the heat-conducting element comprises a portion in contact with surfaces, facing each other, of the two adjacent electric cores, and also a portion in contact with the housing. Optionally, the heat-conducting element is an L-shaped heat pipe. Optionally, the L-shaped heat pipe comprises an elongated extending section and a bending section bent relative to the extending section, wherein the extending section is arranged between two adjacent electric cores to abut the each other opposite surfaces of the two electric cores, and the bending section is arranged between the bottom of an electric core and the bottom of the housing so as to abut the housing. Optionally, the housing consists of a first and a second housing parts. Optionally, the first housing part is configured as the form of a cover, and the second housing part is configured as a hollow body with an opening at one end, wherein the hollow body has a cavity for accommodating the electric core. The opening can be closed by the first housing part. Optionally, the power battery unit further comprises electrodes provided on the first housing part. Optionally, a plurality of heat pipes are provided between the two adjacent electric cores, wherein the plurality of heat pipes are arranged side by side in the length direction of the electric cores. Optionally, the bent portions of the plurality of heat pipes are alternately arranged, in the length direction of the electric cores, between the bottom of one or the other of the two adjacent electric cores and the bottom of the housing. According to another aspect of the disclosure, there is also provided a battery pack comprising the power battery unit as described above. According to yet another aspect of the disclosure, there is also provided a working machine which comprises the aforementioned battery pack. According to the novel design of the power battery unit of the disclosure, the heat-conducting element can directly conduct the heat generated by electric cores from the vicinity of the inner center of the power battery unit to the housing thereof, and dissipate it through the housing, thus realizing rapid, effective and sufficient drop in temperature. When the temperature of the power battery unit needs to be raised, the heat pipe will transfer the heat from the housing of the power battery unit to the electric cores, so as to realize efficient, in-depth and relatively uniform temperature rising. The disclosure will be described in detail by way of non-limiting embodiments with reference to the attached drawings, in which: Fig. 1 is a schematic perspective view of a power battery unit of the disclosure, and is a schematic exploded view of the power battery unit in of Embodiments The power battery unit according to the disclosure will be described below with reference to the drawings. In the following description many specific details are illustrated in order to make those skilled in the art fully understand the disclosure. However, it will be apparent to those skilled in the art that the disclosure may be carried out without some of these specific details. Furthermore, it should be understood that the disclosure is not limited to the specific embodiments described. On the contrary, any combination of the following features and elements can be considered to embody the disclosure, regardless of whether they are described with respect to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustration only and should not be regarded as elements or limitations of the claims unless explicitly stated in the claims. Figs. 1 and 2 schematically show one embodiment of the power battery unit of the disclosure. As shown in Figs. 1 and 2, the power battery unit 100 comprises a housing 10, which may consist of a first housing part 1 and a second housing part 2. The first housing part 1 may be configured in the form of a cover. The second housing part 2 may be configured as a hollow body with an opening at one end. The hollow body may have a cavity for accommodating electric cores 3, and the opening can be closed by the first housing part 1 in the form of a cover. It may be conceived that the housing 10 may also have other forms / configurations. For example, in another embodiment, not shown, the housing may be formed with two substantially identical or mirror-image symmetrical half-housings. As shown in Fig. 2, electrodes 5 may be provided on the first housing part 1. The power battery unit 100 further comprises electric cores 3 accommodated inside the housing 10. Although two electric cores 3 are shown in this embodiment in Fig. 2, in another embodiment which is not shown, the power battery unit may comprise more than two electric cores. The power battery unit 100 may further comprise at least one heat- conducting element 4 arranged between two adjacent electric cores 3. The heat- conducting element 4 may have a portion in contact with the surfaces of the two adjacent electric cores, which surfaces may face each other, and also have another portion in contact with the housing 10. The heat-conducting element 4 may be a heat pipe. In the technical field of battery thermal management, heat pipes are very advantageous in heat dissipation / heating rate and in temperature uniformity of a battery pack. The heat pipe may be made of metal (such as copper or aluminum) that is good at heat conducting. According to this embodiment, the heat pipe may be generally L- shaped, as shown in Fig. 2. Specifically, the heat pipe may comprise an elongated extending section 41 and a bending section 42 bent / angled relative to the extending section 41, in particular extending perpendicularly relative to the extending section 41. The extending section 41 may be arranged between two adjacent electric cores 3 to abut the surfaces of the two electric cores facing each other. The bending section 42 may be arranged between the bottom of the electric core 3 and the bottom of the housing 10 (i.e., the bottom surface of the housing 10 in the cavity), in contact with the housing 10. That is, the L-shaped heat pipe can be arranged in such a way as to abut a side surface of the electric core 3 and a bottom surface thereof adjacent to the side surface, and since the bottom surface of the electric core 3 faces and is supported by the bottom of the housing 10, the portion of the L-shaped heat pipe abutting the bottom surface of the electric core 3 is also close to and in contact with the bottom of the housing 10. Thus, the heat pipe enables the heat generated by the electric core 3 to be directly and efficiently conducted to the housing 10 from the vicinity of the inner center of the power battery unit 100, and dissipated through the housing 10; and vice versa, when the temperature of the power battery unit 100 needs to be raised, the heat pipe will transfer heat from the housing 10 to the electric core 3, in particular to a position of the electric core near the central inside of the power battery unit 100. In this embodiment, a plurality of L-shaped heat pipes (four pipes are shown in Fig. 2) are provided between two adjacent electric cores 3, and these heat pipes are arranged side by side in the length direction of the electric cores 3. As shown in Fig. 2, the bending sections 42 of a plurality of heat pipes are alternately arranged between the bottom of one or the other of two adjacent electric cores 3 and the bottom of the housing 10 in the length direction of the electric cores 3. That is, the bending sections 42 of every two adjacent heat pipes are angled towards the respective bottoms of different electric cores 3, so that in general, these heat pipes can uniformly transfer heat between each electric cores 3 and the housing 10. It may be conceived that in another embodiment not shown, four or more L-shaped heat pipes can be arranged in pairs, so that the bending sections 42 of a first pair of adjacent and parallel heat pipes are both bent towards the bottom of one electric core 3, while a second pair of adjacent and parallel heat pipes are oppositely bent, that is, their bending sections 42 are both bent towards the bottom of the other electric core 3. Industrial Applicability According to the novel design of a power battery unit 100 of the disclosure, at least one heat-conducting element 4, such as heat pipe, is set between adjacent electric cores 3. The heat pipe is configured such that at least a portion thereof (e.g., an elongated extending section 41) is in contact with the surfaces, facing each other, of the two electric cores 3 of the power battery unit 100, and one end thereof (e.g., a bent portion 42 extending perpendicularly to the extending section 41) is in contact with the bottom surface in the cavity of the housing 10 of the power battery unit 100. When the power battery unit 100 is working, the heat pipe can directly conduct the heat generated by the electric core 3 from near the center inside the power battery unit 100 to the housing 10 thereof, and dissipate it through the housing 10, thus resulting in rapid, effective and sufficient cooling. And vice versa, when the temperature of the power battery unit 100 needs to be raised, the heat pipe will transfer the heat from the housing 10 of the power battery unit 100 to the electric core 3 for efficient, in-depth and relatively uniform heating. Therefore, the novel power battery unit according to the disclosure allows the electric core can work at a uniform temperature. In addition, under the condition of low ambient temperature, the power battery unit can be efficiently heated to an appropriate and economical working temperature. It can be understood by those skilled in the art that the above- described embodiments are all exemplary and can be improved by those skilled in the art, and the structures described in various embodiments can be freely combined without conflict in structure or principle. With the preferred embodiments of the disclosure set forth in detail, it will be clear to those skilled in the art that various changes and modifications can be made without departing from the scope and spirit of the appended claims, and the disclosure is not limited to the implementation of the exemplary embodiments recited in the description.

Claims

Claims 1. A power battery unit (100) comprising: a housing (10); and at least two electric cores (3) accommodated in the housing; wherein the power battery unit further comprises at least one heat- conducting element (4) arranged between two adjacent electric cores (3), and wherein the heat-conducting element comprises a portion in contact with surfaces, facing each other, of the two adjacent electric cores, and also a portion in contact with the housing (10).

2. The power battery unit according to claim 1, wherein the heat-conducting element (4) is an L-shaped heat pipe.

3. The power battery unit according to claim 2, wherein the L-shaped heat pipe comprises an elongated extending section (41) and a bending section (42) bent relative to the extending section, and wherein the extending section (41) is arranged between two adjacent electric cores (3) to abut the surfaces of the two electric cores facing each other, and the bending section (42) is arranged between the bottom of the electric core (3) and the bottom of the housing (10) so as to abut the housing.

4. The power battery unit according to claim 1, wherein the housing (10) consists of a first housing part (1) and a second housing part (2).

5. The power battery unit according to claim 4, wherein the first housing part (1) is configured as the form of a cover, and the second housing part (2) is configured as a hollow body with an opening at one end, and wherein the hollow body has a cavity for accommodating the electric cores (3), and the opening can be closed by the first housing part (1).

6. The power battery unit according to claim 4 or 5, further comprising an electrode (5) provided on the first housing part (1).

7. The power battery unit according to any one of claims 3 to 5, wherein a plurality of heat pipes are provided between two adjacent electric cores (3), and wherein the plurality of heat pipes are arranged side by side in the length direction of the electric cores.

8. The power battery unit according to claim 7, wherein the bending sections (42) of the plurality of heat pipes are alternately arranged, in the length direction of the electric cores, between the bottom of one or the other of the two adjacent electric cores and the bottom of the housing (10).

9. A battery pack comprising a power battery unit according to any one of claims 1 to 8.

10. A working machine comprising a battery pack according to claim 9.

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