Lithium battery pack with temperature control function for electric bicycle

Abstract

This utility model provides a lithium battery pack for electric bicycles with temperature control function, including a shell, a cover, and a lithium battery cell bracket. The lithium battery cell bracket is installed inside the shell cavity, the cover is installed on the upper end of the shell and has a battery protection plate, and several lithium battery cell groups are installed on the lithium battery cell bracket. The several lithium battery cell groups are assembled into a lithium battery pack. Each lithium battery cell group has conductive plates on both sides, a temperature sensing element is provided in the middle of the lithium battery pack, and several temperature control switches are provided on the outside of the lithium battery pack. The lithium battery pack and the several temperature control switches are connected in series to the charging and discharging circuit. Through the temperature sensing element and the several temperature control switches on the outside of the lithium battery pack, when the temperature in the middle and outside of the lithium battery pack reaches the threshold, the power-off protection can be performed in time. This achieves relatively comprehensive temperature monitoring of the inside and outside of the lithium battery pack, and timely power-off protection operation can be performed based on the temperature information, which can effectively avoid thermal runaway of the lithium battery pack and has good safety performance.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery pack technology, specifically to a lithium battery pack for electric bicycles with temperature control function. Background Technology

[0002] The lithium battery pack is the primary energy source for electric bicycles, storing enough electrical energy to power the vehicle. Currently, most electric bicycles use lead-acid batteries. However, with the promulgation of new national standards for electric bicycles, higher requirements have been placed on weight and safety. Electric bicycles equipped with traditional lead-acid batteries cannot meet these new standards in terms of weight, safety, and environmental friendliness. Lithium-ion batteries, on the other hand, have advantages such as high energy density, small size, light weight, safety, and environmental friendliness. Applying lithium-ion battery packs to electric bicycles can reduce the overall weight of the bicycles. Currently, lithium batteries still exhibit thermal runaway. When the battery temperature rises to a critical point (typically around 60℃-80℃), a series of irreversible exothermic reactions occur internally, leading to a rapid increase in temperature, smoke, fire, or even explosion. However, existing electric bicycles cannot control the lithium battery pack based on the ambient temperature, posing a significant safety hazard. The safety performance of existing lithium battery packs still needs improvement. Utility Model Content

[0003] The purpose of this invention is to address the shortcomings of the aforementioned technologies by proposing a lithium battery pack for electric bicycles with temperature control function, thereby solving the problems described above.

[0004] This utility model provides a lithium battery pack for electric bicycles with temperature control function, including a shell, a cover, and a lithium battery cell bracket. The lithium battery cell bracket is installed in the inner cavity of the shell. The cover is installed on the upper end of the shell and is provided with a battery protection board. The battery protection board is provided with an integrated control circuit. Several lithium battery cell groups are installed on the lithium battery cell bracket. The several lithium battery cell groups are assembled into a lithium battery pack. Each lithium battery cell group contains several lithium battery cells. Each lithium battery cell group has conductive plates on both sides connected to its electrodes. The several conductive plates are used to connect the several lithium battery cell groups in series. A temperature sensing element is provided in the middle of the lithium battery pack. Several temperature control switches are provided on the outside of the lithium battery pack. The lithium battery pack, the temperature sensing element, and the several temperature control switches are all electrically connected to the battery protection board. The lithium battery pack is connected to the charging and discharging circuit of the electric bicycle through the battery protection board. The several temperature control switches are connected in series with the charging and discharging circuit respectively.

[0005] Preferably, the outer casing is provided with a flexible circuit board for electrically connecting the battery protection board, the lithium battery pack, the temperature sensing element and a plurality of temperature control switches. A plurality of temperature control switches arranged vertically are respectively provided on both sides of the lithium battery pack. Both ends of the flexible circuit board are provided with extensions that bend downward along both sides of the lithium battery pack, and the extensions are electrically connected to the plurality of temperature control switches respectively.

[0006] Preferably, the lithium battery cell support includes a front support and a rear support, and both the front support and the rear support are provided with a plurality of spaced mounting slots for inserting the battery cell end.

[0007] Preferably, the temperature sensing element is attached to the side of the lithium cell located in the middle of the lithium battery pack using thermally conductive adhesive, and several temperature control switches are attached to both sides of the lithium battery pack using thermally conductive adhesive.

[0008] Preferably, each conductive sheet is provided with a plurality of fuses for connection with the electrode.

[0009] Preferably, the fuse is composed of a rectangular piece and a strip piece connected together, the cross-section of the rectangular piece is larger than the cross-section of the strip piece, the rectangular piece is used to be welded to the electrode of the lithium battery cell, and the strip piece is used to connect the rectangular piece and the conductive piece.

[0010] Preferably, the integrated control circuit includes a current detection module, a voltage detection module, and a protection control module.

[0011] Preferably, the outer casing is provided with a heat insulation plate, which is used to separate the inner cavity of the outer casing from the top cover, and the heat insulation plate is provided with a plurality of holes for wires to pass through.

[0012] Preferably, the heat insulation plate is fixed to the gap between it and the outer shell by applying adhesive, and the holes are sealed by applying adhesive after the wires pass through them.

[0013] Preferably, the cover is provided with a power interface and an information collection port that are electrically connected to the battery protection board.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] By combining the integrated control circuit and temperature sensing element on the battery protection board, the temperature information of the middle part of the lithium battery pack is detected in real time. When the temperature reaches the threshold, the integrated circuit cuts off the charging and discharging circuit in time to provide power-off protection. By connecting several temperature control switches set around the outside of the lithium battery pack in series to the charging and discharging circuit, when the temperature on the outside of the lithium battery pack reaches the threshold that triggers the temperature control switch, the temperature control switch is triggered and disconnects the charging and discharging circuit, providing timely power-off protection. This not only provides temperature control protection for the main heat-generating area in the middle of the lithium battery pack, but also provides temperature control protection for the perimeter of the lithium battery pack. This effectively prevents thermal runaway caused by abnormal temperature in the outer area of ​​the lithium battery pack where the temperature sensing element in the middle of the lithium battery pack cannot detect the temperature, achieving comprehensive temperature control protection for the lithium battery pack and improving the safety performance of the lithium battery pack. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the external structure of a certain embodiment of the present utility model;

[0018] Figure 2 This is a cross-sectional view of one embodiment of the present utility model;

[0019] Figure 3 This is a schematic diagram of the rear structure of the flexible circuit board and lithium battery pack in a certain embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the front-end structure of the flexible circuit board and lithium battery pack in a certain embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the lithium battery pack in one embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the structure of the rear support and lithium battery cell assembly in a certain embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of the structure of the conductive sheet and the fuse sheet in a certain embodiment of the present invention.

[0024] In the diagram, 1-outer shell; 11-heat insulation board; 2-cover; 21-battery protection board; 22-power interface; 23-information acquisition port; 3-lithium battery cell bracket; 31-front end bracket; 32-rear end bracket; 4-lithium battery cell assembly; 5-conductive sheet; 6-lithium battery pack; 61-temperature sensing element; 62-temperature control switch; 7-flexible circuit board; 71-extension section; 8-mounting groove; 9-fuse; 91-rectangular piece; 92-strip piece. Detailed Implementation

[0025] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0026] Example 1:

[0027] Reference Figures 1 to 7 This utility model provides a lithium battery pack for electric bicycles with temperature control function, including a shell 1, a cover 2, and a lithium battery cell bracket 3. The lithium battery cell bracket 3 is installed in the inner cavity of the shell 1. The cover 2 is installed on the upper end of the shell 1 and is provided with a battery protection board 21. The battery protection board 21 is provided with an integrated control circuit. Several lithium battery cell groups 4 are installed on the lithium battery cell bracket 3. The several lithium battery cell groups 4 are assembled into a lithium battery pack 6. Each lithium battery cell group 4 contains several lithium battery cells. Each lithium battery cell group 4 has conductive plates 5 connected to its electrodes on both sides. The several conductive plates 5 are used to connect the several lithium battery cell groups 4 in series. A temperature sensing element 61 is provided in the middle of the lithium battery pack 6. Several temperature control switches 62 are provided on the outside of the lithium battery pack 6. The lithium battery pack 6, the temperature sensing element 61, and the several temperature control switches 62 are all electrically connected to the battery protection board 21. The lithium battery pack 6 is connected to the charging and discharging circuit of the electric bicycle through the battery protection board 21. The several temperature control switches 62 are connected in series with the charging and discharging circuit respectively.

[0028] The integrated control circuit on the battery protection board 21 works in conjunction with the temperature sensing element 61 to detect the temperature information in the middle of the lithium battery pack 6 in real time. When the temperature reaches the threshold, the integrated circuit promptly cuts off the charging and discharging circuit for power-off protection. By connecting several temperature control switches 62 arranged around the outside of the lithium battery pack 6 in series to the charging and discharging circuit, when the temperature on the outside of the lithium battery pack 6 reaches the threshold for triggering the temperature control switch 62, the temperature control switch 62 is triggered and disconnects the charging and discharging circuit, thus providing timely power-off protection. This not only achieves temperature control protection for the main heat-generating area in the middle of the lithium battery pack, but also provides temperature control protection for the periphery of the lithium battery pack. This effectively prevents thermal runaway caused by abnormal temperature in the outer area of ​​the lithium battery pack where the temperature sensing element 61 in the middle of the lithium battery pack cannot detect the temperature, achieving comprehensive temperature control protection for the lithium battery pack and improving the safety performance of the lithium battery pack.

[0029] Among them, the temperature sensing element 61 is an NTC thermistor, and the temperature control switch 62 is a dual ceramic plate temperature control switch 62 made of ceramic materials with different expansion coefficients.

[0030] Specifically, the outer casing 1 is provided with a flexible circuit board 7 for electrically connecting the battery protection board 21, the lithium battery pack 6, the temperature sensing element 61 and several temperature control switches 62. Several temperature control switches 62 arranged vertically are provided on both sides of the lithium battery pack 6. Both ends of the flexible circuit board 7 are provided with extensions 71 that bend downwards along both sides of the lithium battery pack 6. The extensions 71 are electrically connected to several temperature control switches 62 respectively.

[0031] A flexible circuit board 7 is placed on top of the lithium battery pack 6. The flexible circuit board 7 is electrically connected to the battery protection board 21, the lithium battery pack 6, and the temperature sensing element 61. The extensions 71 at both ends of the flexible circuit board 7 that bend downwards along both sides of the lithium battery pack 6 facilitate the electrical connection of the extensions 71 of the temperature control switches 62 located on both sides of the lithium battery pack 6. That is, the extensions 71 are connected sequentially to several temperature control switches 62 arranged vertically along both sides of the lithium battery pack 6, simplifying the wiring method, reducing wiring operations and wiring errors, and providing operational convenience for wiring personnel.

[0032] As an explanation of this embodiment, without the extension section 71 structure, the temperature control switches 62 at each location need to be wired together to the battery protection board 21 at the top of the lithium battery pack 6. This wiring method easily leads to the wires of multiple temperature control switches 62 being wired together, which can easily result in wire tangling and wiring errors. Wiring personnel need to constantly untangle the wires before proceeding, making the wiring operation difficult and labor-intensive. However, by using the extension section 71 structure aligned with several temperature control switches 62, wiring can be performed at the installation position of each temperature control switch 62, improving the wiring structure, reducing wire tangling, and providing operational convenience for wiring personnel.

[0033] A support plate can be attached to the middle of the flexible circuit board 7 to support the entire flexible circuit board 7, making it easier to place the flexible circuit board 7 at the end of the lithium battery pack 6 for wiring operations.

[0034] Example 2:

[0035] Reference Figures 1 to 7 In conjunction with the technical solution of Embodiment 1, in this embodiment, the lithium battery cell support 3 includes a front support 31 and a rear support 32. Both the front support 31 and the rear support 32 are provided with a plurality of spaced mounting slots 8, which are used for inserting the battery cell end.

[0036] Specifically, the temperature sensing element 61 is attached to the side of the lithium battery cell located in the middle of the lithium battery pack 6 with thermally conductive adhesive, and several temperature control switches 62 are attached to both sides of the lithium battery pack 6 with thermally conductive adhesive.

[0037] When installing the lithium battery cell pack 4, insert several lithium battery cells into the rear bracket 32. During the installation of the lithium battery cells, fix the temperature sensing element 61 to the outside of the corresponding lithium battery cell at the middle position of the rear bracket 32 ​​with thermally conductive adhesive. Lead the wire of the temperature sensing element 61 to the top position of the lithium battery pack 6. Install the other lithium battery cells one by one onto the rear bracket 32. Then cover the front bracket 31 and insert it into several lithium battery cells respectively to complete the assembly of the lithium battery pack 6.

[0038] Several conductive sheets 5 are connected to the two ends of several lithium cells on the lithium battery pack 6 respectively. The electrodes and conductive sheets 5 are connected by welding. Due to the limiting effect of the electrode sheets, the lithium cells are not easy to separate from the front support 31 and the rear support 32, which plays a certain role in fixing the entire lithium battery pack 6.

[0039] Example 3:

[0040] Reference Figures 1 to 7 In combination with the technical solutions of Embodiment 1 and Embodiment 2, in this embodiment, each conductive sheet 5 is provided with a plurality of fuses 9 for connection with the electrode.

[0041] By installing a fuse 9 at each lithium battery cell, when an abnormal temperature rise occurs at a lithium battery cell, the fuse 9 at that location will melt and remove the lithium battery cell from the charging and discharging circuit, thus preventing the continuous temperature rise of that lithium battery cell from affecting the operation of other lithium battery cells and improving safety performance.

[0042] Specifically, the fuse 9 is composed of a rectangular piece 91 and a strip piece 92 connected together. The cross-section of the rectangular piece 91 is larger than the cross-section of the strip piece 92. The rectangular piece 91 is used to be welded to the electrode of the lithium battery cell, and the strip piece 92 is used to connect the rectangular piece 91 and the conductive piece 5.

[0043] The fuse element 9 is composed of a large rectangular piece 91 and a small strip piece 92. The strip piece 92, due to its small cross-sectional area, is easier to melt and serves as the main fuse element, providing timely protection in case of abnormal electrical temperature rise. The rectangular piece 91, with its larger overall area, effectively increases the connection area between the fuse element 9 and the electrode. Compared to the small strip piece 92, the large rectangular piece 91 is easier to weld, facilitating the welding process.

[0044] Example 4:

[0045] Reference Figures 1 to 7 In conjunction with the technical solutions of embodiments 1-3, in this embodiment, the integrated control circuit includes a current detection module, a voltage detection module, and a protection control module.

[0046] The integrated control circuit, primarily based on an MCU, collaborates with current detection, voltage detection, and protection control modules to detect and control the lithium battery pack. The current and voltage detection modules, working in conjunction with the integrated control circuit, utilize voltage divider resistors, shunt resistors, amplifiers, and an ADC to detect current and voltage. This use of voltage divider resistors, shunt resistors, amplifiers, and an ADC for current and voltage detection is existing technology and will not be elaborated upon further in this application. The protection control module, based on the current and voltage information detected by the current and voltage detection modules, uses integrated circuit-controlled MOSFET switches to control the on / off state of the charging and discharging circuits, thereby executing overcharge, over-discharge, overcurrent, and short-circuit protection actions.

[0047] When the centralized control circuit, in conjunction with the temperature sensing element 61, detects that the temperature in the middle of the lithium battery pack has reached the threshold, it disconnects the charging and discharging circuit through its protection control module to achieve power failure protection.

[0048] When the current detection module and voltage detection module in the integrated control circuit detect an abnormality in the charging and discharging circuit, they can work with the control protection module to disconnect the charging and discharging circuit and achieve power-off protection. Specifically, when the fuse 9 at a certain lithium battery cell blows, the current detection module will detect the current change and cut off the power in time, which can effectively prevent the entire lithium battery pack from malfunctioning in non-rated working environments.

[0049] Example 5:

[0050] Reference Figures 1 to 7 In conjunction with the technical solutions of embodiments 1-4, in this embodiment, a heat insulation plate 11 is provided on the outer shell 1. The heat insulation plate 11 is used to separate the inner cavity of the outer shell 1 from the top cover. The heat insulation plate 11 is provided with a number of holes for wires to pass through.

[0051] Specifically, the heat insulation plate 11 is fixed to the outer shell 1 by applying glue, and several holes are sealed by applying glue after the wires pass through them.

[0052] By installing the heat insulation plate 11 by applying adhesive, the lithium battery pack 6 inside the outer casing 1 is separated from the battery protection plate 21 at the cover 2, which can reduce the impact of the heat generated by the lithium battery pack 6 on the battery protection plate 21, and the battery protection plate 21 can be used to monitor and manage the lithium battery pack 6 normally.

[0053] Specifically, the cover 2 is equipped with a power interface 22 and an information acquisition port 23 that are electrically connected to the battery protection board 21. The entire lithium battery pack is connected to the charging and discharging circuit of the electric bicycle through the power interface 22, and a dedicated information acquisition device can be connected through the information acquisition port 23 to collect the working status information of the entire lithium battery pack, which is beneficial for further detection and monitoring of the lithium battery pack.

[0054] The structure shown in the attached drawings of this application consists of nine lithium-ion cells connected in parallel to form a lithium-ion cell group 4, and four lithium-ion cell groups 4 connected in series to form a lithium-ion battery pack 6.

[0055] The above description is merely a preferred embodiment of this utility model and does not constitute any limitation on this utility model. Any person skilled in the art can make many possible variations and modifications to the technical solution of this utility model, or modify it into equivalent embodiments, without departing from the scope of the technical solution of this utility model. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technology of this utility model without departing from the scope of the technical solution of this utility model shall fall within the protection scope of this technical solution.

Claims

1. A lithium battery pack for an electric bicycle with temperature control function, characterized in that, The device includes a housing, a cover, and a lithium battery cell support. The lithium battery cell support is installed inside the housing. The cover is installed on the upper part of the housing and has a battery protection board. The battery protection board has an integrated control circuit. Several lithium battery cell groups are installed on the lithium battery cell support. The several lithium battery cell groups are assembled into a lithium battery pack. Each lithium battery cell group contains several lithium battery cells. Each lithium battery cell group has conductive plates on both sides connected to its electrodes. The conductive plates are used to connect the several lithium battery cell groups in series. A temperature sensing element is provided in the middle of the lithium battery pack. Several temperature control switches are provided on the outside of the lithium battery pack. The lithium battery pack, the temperature sensing element, and the several temperature control switches are all electrically connected to the battery protection board. The lithium battery pack is connected to the charging and discharging circuit of an electric bicycle through the battery protection board. The several temperature control switches are connected in series with the charging and discharging circuit.

2. The lithium battery pack for electric bicycles with temperature control function according to claim 1, characterized in that: The outer casing is provided with a flexible circuit board for electrically connecting the battery protection board, the lithium battery pack, the temperature sensing element and a plurality of temperature control switches. A plurality of temperature control switches are respectively provided on both sides of the lithium battery pack and arranged in a vertical direction. Both ends of the flexible circuit board are provided with extensions that bend downward along both sides of the lithium battery pack, and the extensions are electrically connected to the plurality of temperature control switches respectively.

3. A lithium battery pack for electric bicycles with temperature control function according to claim 1, characterized in that: The lithium battery cell support includes a front support and a rear support. Both the front support and the rear support are provided with a number of spaced mounting slots for inserting the battery cell end.

4. A lithium battery pack for electric bicycles with temperature control function according to claim 1, characterized in that: The temperature sensing element is attached to the side of the lithium cell located in the middle of the lithium battery pack using thermally conductive adhesive, and several temperature control switches are attached to both sides of the lithium battery pack using thermally conductive adhesive.

5. A lithium battery pack for electric bicycles with temperature control function according to claim 1, characterized in that: Each of the conductive sheets is provided with a number of fuses for connection with the electrodes.

6. A lithium battery pack for electric bicycles with temperature control function according to claim 5, characterized in that: The fuse is composed of a rectangular piece and a strip piece connected together. The cross-section of the rectangular piece is larger than the cross-section of the strip piece. The rectangular piece is used to be welded to the electrode of the lithium battery cell, and the strip piece is used to connect the rectangular piece and the conductive piece.

7. A lithium battery pack for electric bicycles with temperature control function according to any one of claims 1-6, characterized in that: The integrated control circuit includes a current detection module, a voltage detection module, and a protection control module.

8. A lithium battery pack for electric bicycles with temperature control function according to claim 1, characterized in that: The outer casing is provided with a heat insulation plate, which is used to separate the inner cavity of the outer casing from the top cover. The heat insulation plate is provided with a number of holes for wires to pass through.

9. A lithium battery pack for electric bicycles with temperature control function according to claim 1, characterized in that: The heat insulation plate is fixed to the outer shell by applying adhesive, and the holes are sealed by applying adhesive after the wires pass through them.

10. A lithium battery pack for electric bicycles with temperature control function according to claim 1, characterized in that: The cover is equipped with a power interface and an information collection port that are electrically connected to the battery protection board.

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