Lithium battery pack with temperature control function for electric bicycle

Abstract

The invention provides an electric bicycle lithium battery pack with a temperature control function, which comprises a shell, a sealing cover and a lithium battery core bracket, the lithium battery core bracket is arranged in the inner cavity of the shell, the sealing cover is arranged at the upper end of the shell and is provided with a battery protection plate, a plurality of lithium battery core groups are arranged on the lithium battery core bracket, and the plurality of lithium battery core groups are assembled into a lithium battery pack. Conducting pieces are arranged on the two sides of each lithium battery core set, a temperature sensing element is arranged in the middle of the lithium battery pack, a plurality of temperature control switches are arranged on the outer side of the lithium battery pack, and the lithium battery pack and the temperature control switches are connected into a charging and discharging loop in series. When the temperature of the middle part and the outer side of the lithium battery pack reaches a threshold value, power-off protection can be carried out in time, relatively comprehensive temperature monitoring on the interior and the periphery of the lithium battery pack is realized, power-off protection operation is carried out in time according to the temperature information, a thermal runaway phenomenon of the lithium battery pack can be effectively avoided, and good safety performance is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery packs, and in particular to a lithium battery pack for an electric bicycle with a temperature control function. Background Art

[0002] The lithium-ion battery pack of an electric bicycle is its primary energy source, 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 weight and safety requirements have been imposed. Electric bicycles equipped with traditional lead-acid batteries fail to meet these requirements. Lithium-ion batteries, on the other hand, offer high energy density, compact size, light weight, safety, and environmental friendliness. Their application in electric bicycles can reduce the overall weight of electric bicycles. Currently, lithium-ion batteries are subject to thermal runaway. This occurs when the battery temperature reaches a critical point, typically starting around 60°C-80°C, and a series of irreversible exothermic reactions occur within the battery, causing a rapid temperature increase and potentially leading to smoke, fire, and even explosion. However, existing electric bicycles cannot control the lithium-ion battery pack's temperature based on the ambient temperature, posing a significant safety hazard. The safety performance of existing lithium-ion battery packs remains to be improved. Summary of the Invention

[0003] The purpose of the present invention is to address the deficiencies in the above-mentioned technologies and to propose a lithium battery pack for electric bicycles with a temperature control function, aiming to solve the above-mentioned problems.

[0004] The present invention provides a lithium battery pack for an electric bicycle with a temperature control function, comprising a shell, a cover and a lithium battery cell holder, the lithium battery cell holder being installed in the inner cavity of the shell, the cover being installed at the upper end of the shell and being provided with a battery protection board, the battery protection board being provided with an integrated control circuit, a plurality of lithium battery cell groups being installed on the lithium battery cell holder, the plurality of lithium battery cell groups being assembled into a lithium battery pack, each of the lithium battery cell groups comprising a plurality of lithium battery cells, conductive sheets connected to electrodes thereof being provided on both sides of each lithium battery cell group, the plurality of conductive sheets being used to connect the plurality of lithium battery cell groups in series, a temperature sensing element being provided in the middle of the lithium battery pack, a plurality of temperature controlled switches being provided on the outside of the lithium battery pack, the lithium battery pack, the temperature sensing element and the plurality of temperature controlled switches being electrically connected to the battery protection board, the lithium battery pack being connected to a charge and discharge circuit of the electric bicycle through the battery protection board, and the plurality of temperature controlled switches being respectively connected in series with the charge and discharge circuit.

[0005] Preferably, a flexible circuit board is provided on the outer shell for electrically connecting the battery protection board, the lithium battery pack, the temperature sensing element and several of the temperature control switches. Several of the temperature control switches arranged in a vertical direction are respectively provided on both sides of the lithium battery pack. Both ends of the flexible circuit board are provided with extensions bent downward along both sides of the lithium battery pack, and the extensions are electrically connected to several of the temperature control switches respectively.

[0006] Preferably, the lithium battery cell bracket includes a front bracket and a rear bracket, and the front bracket and the rear bracket are both provided with a plurality of installation slots arranged at intervals, and the installation slots are used for the battery cell ends to be plugged in.

[0007] Preferably, the temperature sensing element is fixed to the side of the lithium battery cell located in the middle of the lithium battery pack by means of thermally conductive adhesive, and a plurality of the temperature control switches are fixed to both sides of the lithium battery pack by means of thermally conductive adhesive.

[0008] Preferably, each of the conductive sheets is provided with a plurality of fuse sheets for connecting to electrodes.

[0009] Preferably, the fuse piece 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 on 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, a heat insulation board is provided on the shell, and the heat insulation board is used to separate the inner cavity of the shell from the top cover. The heat insulation board is provided with a plurality of holes for the wires to pass through.

[0012] Preferably, the gap between the heat insulation board and the shell is fixed by gluing, and several holes are sealed by gluing after the wires pass through them.

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

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

[0015] By cooperating with the integrated control circuit on the battery protection board and the temperature sensor element, the temperature information of the middle position of the lithium battery pack is detected in real time. When the temperature reaches the threshold, the integrated circuit promptly cuts off the charge and discharge circuit for power-off protection. By connecting several temperature control switches arranged on the four sides of the outside of the lithium battery pack in series to the charge and discharge circuit, when the outside temperature of the lithium battery pack reaches the threshold for triggering the temperature control switch, the temperature control switch is triggered and disconnects the charge and discharge circuit to perform power-off protection in time. That is, on the basis of achieving temperature control protection for the main heating area in the middle of the lithium battery pack, further temperature control protection is performed on the four sides of the lithium battery pack, which can effectively avoid thermal runaway due to abnormal temperature in the outer area of ​​the lithium battery pack where the temperature sensor element in the middle cannot detect the temperature, thereby achieving comprehensive temperature control protection for the lithium battery pack and improving the safety performance of the lithium battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 A schematic diagram of the external structure of an embodiment of the present invention;

[0018] Figure 2 is a cross-sectional view of an embodiment of the present invention;

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

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

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

[0022] Figure 6 This is a structural diagram of a rear end bracket and a lithium battery cell assembly in one embodiment of the present invention;

[0023] Figure 7 Schematic diagram of the structure of the conductive piece and the fuse piece in an embodiment of the present invention.

[0024] In the figure, 1-housing; 11-heat insulation board; 2-cover; 21-battery protection board; 22-power interface; 23-information collection port; 3-lithium battery cell bracket; 31-front bracket; 32-rear bracket; 4-lithium battery cell group; 5-conductive sheet; 6-lithium battery pack; 61-temperature sensor element; 62-temperature control switch; 7-flexible circuit board; 71-extension part; 8-mounting slot; 9-fuse piece; 91-rectangular piece; 92-strip piece. DETAILED DESCRIPTION

[0025] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0026] Example 1:

[0027] Reference Figures 1 to 7 The present invention provides a lithium battery pack for an electric bicycle with a temperature control function, comprising a shell 1, a cover 2 and a lithium battery holder 3, the lithium battery holder 3 is installed in the inner cavity of the shell 1, the cover 2 is installed at 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, a plurality of lithium battery cell groups 4 are installed on the lithium battery holder 3, and the plurality of lithium battery cell groups 4 are assembled into a lithium battery group 6, each lithium battery group 4 includes a plurality of lithium battery cells, and each lithium battery cell group 4 is provided with conductive sheets 5 connected to its electrodes on both sides, and the plurality of conductive sheets 5 are used to connect the plurality of lithium battery cell groups 4 in series, a temperature sensing element 61 is provided in the middle of the lithium battery group 6, and a plurality of temperature control switches 62 are provided on the outside of the lithium battery group 6, the lithium battery group 6, the temperature sensing element 61 and the plurality of temperature control switches 62 are all electrically connected to the battery protection board 21, the lithium battery group 6 is connected to the charging and discharging circuit of the electric bicycle through the battery protection board 21, and the plurality of temperature control switches 62 are respectively connected in series with the charging and discharging circuit.

[0028] The integrated control circuit on the battery protection board 21 cooperates with the temperature sensor element 61 to detect the temperature information of the middle position of the lithium battery pack 6 in real time. When the temperature reaches the threshold, the integrated circuit promptly cuts off the charge and discharge circuit for power-off protection. By connecting a plurality of temperature control switches 62 arranged on the four sides of the outside of the lithium battery pack 6 in series to the charge and discharge circuit, when the outside temperature 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 charge and discharge circuit, and power-off protection is promptly performed. That is, on the basis of achieving temperature control protection for the main heating area in the middle of the lithium battery pack, further temperature control protection is performed on the surrounding areas of the lithium battery pack, which can effectively avoid thermal runaway due to abnormal temperature in the outer area of ​​the lithium battery pack where the temperature sensor element 61 in the middle cannot detect the temperature, thereby achieving comprehensive temperature control protection for the lithium battery pack and improving the safety performance of the lithium battery pack.

[0029] The temperature sensing element 61 is an NTC thermistor, and the temperature control switch 62 is a double-ceramic temperature control switch 62 made of ceramic materials with different expansion coefficients.

[0030] Specifically, the outer shell 1 is provided with a flexible circuit board 7 for electrically connecting the battery protection board 21, the lithium battery pack 6, the temperature sensor element 61 and a plurality of temperature control switches 62. A plurality of temperature control switches 62 arranged in a vertical direction are respectively 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 downward along both sides of the lithium battery pack 6. The extensions 71 are respectively electrically connected to the plurality of temperature control switches 62.

[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 sensor element 61, respectively. The extensions 71 at both ends of the flexible circuit board 7 are bent downward along both sides of the lithium battery pack 6, so that the temperature control switches 62 on both sides of the lithium battery pack 6 can be electrically connected to the extensions 71 respectively. That is, the extensions 71 are connected in sequence to several temperature control switches 62 arranged vertically along both sides of the lithium battery pack 6, which simplifies the wiring method, reduces wiring operations and wiring errors, and provides operational convenience for wiring personnel.

[0032] As an explanation of this embodiment, without the use of the extension portion 71 structure, the temperature control switches 62 at various locations need to be wired together to the battery protection plate 21 at the top of the lithium battery pack 6. This wiring method easily causes the wiring of multiple temperature control switches 62 to be centrally connected, which can easily lead to wiring errors due to wire confusion. The wiring operator must constantly sort out the wires before wiring, which is difficult and labor-intensive. However, using the extension portion 71 structure that aligns with multiple temperature control switches 62, the wiring operation can be performed at the installation location of each temperature control switch 62, improving the wiring structure, reducing wire entanglement, and providing operational convenience for the wiring operator.

[0033] A mounting support plate may 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 Combined with the technical solution of Example 1, in this embodiment, the lithium battery cell bracket 3 includes a front end bracket 31 and a rear end bracket 32. The front end bracket 31 and the rear end bracket 32 ​​are both provided with a plurality of spaced mounting grooves 8, and the mounting grooves 8 are used for plugging the ends of the battery cells.

[0036] Specifically, the temperature sensing element 61 is fixed to the side of the lithium battery cell located in the middle of the lithium battery pack 6 by means of thermal conductive adhesive, and a plurality of temperature control switches 62 are fixed to both sides of the lithium battery pack 6 by means of thermal conductive adhesive.

[0037] When installing the lithium battery pack 4, several lithium battery cells are inserted into the rear end bracket 32. During the installation of the lithium battery cells, the temperature sensor element 61 is fixed to the outside of the corresponding lithium battery cell at the middle position of the rear end bracket 32 ​​by using thermal conductive glue, and the wire of the temperature sensor element 61 is led out to the top position of the lithium battery pack 6. The other lithium battery cells are installed on the rear end bracket 32 ​​one by one, and then the front end bracket 31 is covered and plugged into several lithium battery cells respectively to complete the assembly of the lithium battery pack 6.

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

[0039] Example 3:

[0040] Reference Figures 1 to 7 Combining the technical solutions of Example 1 and Example 2, in this embodiment, each conductive sheet 5 is provided with a plurality of fuse sheets 9 for connecting to the electrodes.

[0041] By providing 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 charge and discharge circuit, thereby preventing the lithium battery cell from continuing to heat up and affecting the operation of other lithium battery cells, thereby improving safety performance.

[0042] Specifically, the fuse piece 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 on 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] Fuse link 9 is composed of a larger rectangular piece 91 and a smaller strip piece 92. Strip piece 92, due to its smaller cross-sectional area, is more likely to fuse. As the primary fuse, it provides immediate protection against abnormal electrical temperature rise. The larger rectangular piece 91 effectively increases the connection area between the fuse link 9 and the electrode. Furthermore, compared to the smaller strip piece 92, the larger rectangular piece 91 is easier to weld, facilitating the welding process.

[0044] Example 4:

[0045] Reference Figures 1 to 7 In combination with the technical solutions of Examples 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 mainly uses the MCU as the core and cooperates with the current detection module, voltage detection module and protection control module to realize the detection and control of the lithium battery pack. Among them, the current monitoring module and the voltage detection module cooperate with the integrated control circuit to realize the detection of current and voltage through the voltage divider resistor, shunt resistor, amplifier and ADC. The use of voltage divider resistor, shunt resistor, amplifier and ADC to realize the detection of current and voltage belongs to the existing current and voltage detection technology and will not be repeated in this application. The protection control module cooperates with the integrated control circuit to control the on and off of the charge and discharge circuit through each MOSFET switch controlled by the integrated circuit based on the current and voltage information detected by the current detection module and the voltage detection module, thereby performing overcharge, over-discharge, overcurrent, short circuit and other protection actions.

[0047] When the centralized control circuit cooperates with the temperature sensor element 61 to monitor that the temperature in the middle of the lithium battery pack reaches the threshold, the protection control module disconnects the charge and discharge circuit to achieve power-off protection;

[0048] When the current detection module and voltage detection module in the integrated control circuit detect an abnormality in the charge and discharge circuit, they can cooperate with the control protection module to disconnect the charge and discharge circuit to achieve power-off protection; among them, when the fuse 9 at a certain lithium battery cell melts, 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 operating abnormally in a non-rated working environment.

[0049] Example 5:

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

[0051] Specifically, the gap between the heat insulation board 11 and the shell 1 is fixed by gluing, and several holes are sealed by gluing after the wires pass through them.

[0052] The heat insulation board 11 is installed by gluing to separate the lithium battery pack 6 inside the shell 1 from the battery protection board 21 at the cover 2, which can reduce the impact of the heat generated by the lithium battery pack 6 on the battery protection board 21 and use the battery protection board 21 to monitor and manage the lithium battery pack 6 normally.

[0053] Specifically, the cover 2 is provided with a power interface 22 and an information collection port 23, which are electrically connected to the battery protection board 21. The power interface 22 connects the entire lithium battery pack to the charging and discharging circuit of the electric bicycle. The information collection port 23 connects to a dedicated information collector to collect operating status information of the entire lithium battery pack, facilitating further testing and monitoring of the lithium battery pack.

[0054] The structure shown in the drawings of the present application comprises nine lithium battery cells connected in parallel to form a lithium battery cell group 4 and four lithium battery cell groups 4 connected in series to form a lithium battery group 6 .

[0055] The above are only preferred embodiments of the present invention and are not intended to limit the present invention in any form. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, use the above technical content to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any changes, modifications, equivalent changes and modifications made to the above embodiments based on the technology of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the present technical solution.

Claims

1. A lithium battery pack for electric bicycle with temperature control function, characterized in that: It includes a shell, a cover and a lithium battery cell holder, the lithium battery cell holder 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, a plurality of lithium battery cell groups are installed on the lithium battery cell holder, and the plurality of lithium battery cell groups are assembled into a lithium battery group, each of the lithium battery cell groups contains a plurality of lithium battery cells, and each of the lithium battery cell groups is provided with conductive sheets connected to its electrodes on both sides, and the plurality of conductive sheets are used to connect the plurality of lithium battery cell groups in series, a temperature sensor element is provided in the middle of the lithium battery group, and a plurality of temperature control switches are provided on the outside of the lithium battery group, the lithium battery group, the temperature sensor element and the plurality of 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, and the plurality of temperature control switches are respectively connected in series with the charging and discharging circuit.

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

3. The lithium battery pack for electric bicycle with temperature control function according to claim 1, characterized in that: The lithium battery cell bracket includes a front bracket and a rear bracket. The front bracket and the rear bracket are both provided with a plurality of installation slots arranged at intervals. The installation slots are used for inserting the ends of the battery cells.

4. The lithium battery pack for an electric bicycle with a temperature control function according to claim 1, characterized in that: The temperature sensing element is fixed to the side of the lithium battery cell located in the middle of the lithium battery pack by means of thermal conductive adhesive, and a plurality of temperature control switches are fixed to both sides of the lithium battery pack by means of thermal conductive adhesive.

5. The lithium battery pack for electric bicycle with temperature control function according to claim 1, characterized in that: Each of the conductive sheets is provided with a plurality of fuse sheets for connecting with electrodes.

6. The lithium battery pack for electric bicycle with temperature control function according to claim 5, characterized in that: The fuse piece is composed of a rectangular piece and a strip piece connected together. The cross section of the rectangular piece is larger than that of the strip piece. The rectangular piece is used to be welded on 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 with temperature control function for an electric bicycle according to any one of claims 1 to 6, characterized in that: The integrated control circuit includes a current detection module, a voltage detection module and a protection control module.

8. The lithium battery pack for electric bicycle with temperature control function according to claim 1, characterized in that: The shell is provided with a heat insulation board, and the heat insulation board is used to separate the inner cavity of the shell from the top cover. The heat insulation board is provided with a plurality of holes for the wires to pass through.

9. The lithium battery pack with temperature control function for electric bicycle according to claim 1, characterized in that: The gap between the heat insulation board and the shell is fixed by gluing, and a plurality of holes are sealed by gluing after the wires pass through them.

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

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