Battery pack

Abstract

The utility model discloses a battery pack which comprises a battery cell group, a pre-tightening belt, an air cylinder, a first end plate and a second end plate, the first end plate abuts against one end of the battery cell group, the second end plate and the other end of the battery cell group are arranged in a spaced mode to form an adjusting gap, and the pre-tightening belt is wound on the peripheral wall of the first end plate and the peripheral wall of the second end plate. A shell of the air cylinder is fixedly installed on the second end plate, and the piston end of the air cylinder penetrates through the adjusting gap to abut against the battery cell set. The first end plate and the second end plate at the two ends of the battery cell group are fastened through the pre-tightening belt, an adjusting gap formed by the second end plate and the battery cell group in a spaced mode provides space for displacement of a piston of the air cylinder, the thickness of the battery cell group is gradually increased along with circulation or deepened aging in the whole life cycle of the battery cell group, and therefore the pre-tightening force of the pre-tightening belt is gradually increased, and the service life of the battery cell group is prolonged. At the moment, the air cylinder drives the piston to retract so as to release overlarge pressure applied by the pre-tightening belt, and damage to the battery cell group caused by overlarge pre-tightening force is avoided.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery packs. Background Technology

[0002] While lithium batteries offer advantages such as high energy density and long cycle life, they still face stringent requirements regarding cycle life and safety in practical applications. During module assembly, to reduce internal resistance and ensure tight electrode adhesion, end plates and steel strips are typically used to apply a fixing preload. However, this rigid preload fluctuates with changes in cell thickness during charging and discharging, and gradually increases due to the volume expansion of active materials with increasing cycle count. This phenomenon can easily lead to a mismatch between the preload and cell expansion, causing mechanical fatigue and interface degradation, thereby shortening battery life and affecting performance stability. Utility Model Content

[0003] To address the aforementioned technical problems, this utility model proposes a battery pack that uses a cylinder to drive a piston to retract, thereby releasing excessive pressure applied by the pre-tensioning band and preventing damage to the battery cell assembly caused by excessive pre-tensioning force.

[0004] The technical solution adopted by this utility model is as follows: A battery pack includes a cell assembly, a pre-tensioning band, a cylinder, a first end plate, and a second end plate. The first end plate abuts against one end of the cell assembly, and the second end plate is spaced apart from the other end of the cell assembly to form an adjustment gap. The pre-tensioning band is wrapped around the outer peripheral walls of the first end plate and the second end plate. The housing of the cylinder is fixedly installed on the second end plate, and the piston end of the cylinder passes through the adjustment gap and abuts against the cell assembly.

[0005] Optionally, the piston end of the cylinder is provided with a pressure plate, the area of ​​which is consistent with the area of ​​the battery cell assembly facing the pressure plate.

[0006] Optionally, it also includes a housing, in which the battery cell assembly, pretension band, first end plate, and second end plate are all located. The cylinder is connected to a high-pressure gas cylinder via an air pipe. The air pipe is equipped with an exhaust valve, an intake valve, and a pressure acquisition device. The intake end of the intake valve is connected to the high-pressure gas cylinder, and the outlet end of the intake valve is connected to the cylinder. The intake end of the exhaust valve is connected to the cylinder, and the outlet end of the exhaust valve is connected to the inside of the housing, or the outlet end of the exhaust valve is connected to the outside of the housing. The pressure acquisition device is used to collect the pressure of the cylinder.

[0007] Optionally, the moving distance of the piston end of the cylinder is 1% to 10% of the thickness of the battery cell assembly.

[0008] Optionally, the high-pressure gas cylinder is installed at the bottom of the housing and is located below the cylinder. The high-pressure gas cylinder and the cylinder are connected by the gas pipe along the inner wall of the housing.

[0009] Optionally, the gas stored in the high-pressure gas cylinder is an inert gas, such as nitrogen or argon, and the pressure resistance of the high-pressure gas cylinder is greater than 2 MPa.

[0010] Optionally, the exhaust valve outlet is provided with a muffler for reducing exhaust noise.

[0011] Optionally, the pretensioning band is a plurality of parallel steel strips, which are evenly distributed circumferentially along the first end plate and the second end plate.

[0012] The beneficial effects of this utility model are: the first end plate and the second end plate at both ends of the battery cell assembly are fastened by a pre-tightening band. The adjustment gap formed by the second end plate and the battery cell assembly provides space for the displacement of the cylinder piston. Throughout the entire life cycle, as the cycle progresses or aging deepens, the thickness of the battery cell assembly gradually increases, so the pre-tightening force of the pre-tightening band gradually increases. At this time, the cylinder drives the piston to retract to release the excessive pressure applied by the pre-tightening band, thus avoiding damage to the battery cell assembly caused by excessive pre-tightening force. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the battery pack structure proposed in an embodiment of the present invention;

[0014] Figure 2 This is a schematic diagram of the air intake valve and air exhaust valve of the battery pack according to an embodiment of the present invention.

[0015] The labels in the attached figures are as follows: 1. Battery cell assembly; 2. Pre-tensioning belt; 3. Cylinder; 4. First end plate; 5. Second end plate; 6. Pressure plate; 7. Air pipe; 8. High-pressure gas cylinder; 9. Exhaust valve; 10. Inlet valve; 11. Air pressure acquisition instrument; 12. Silencer. Detailed Implementation

[0016] The present application will now be described in further detail with reference to the accompanying drawings and embodiments.

[0017] like Figure 1 and 2As shown, this embodiment discloses a battery pack, including a cell assembly 1, a pretensioning band 2, a cylinder 3, a first end plate 4, and a second end plate 5. The first end plate 4 abuts against one end of the cell assembly 1, and the second end plate 5 is spaced apart from the other end of the cell assembly 1 to form an adjustment gap. The pretensioning band 2 is wrapped around the outer peripheral walls of the first end plate 4 and the second end plate 5. The housing of the cylinder 3 is fixedly installed on the second end plate 5, and the piston end of the cylinder 3 passes through the adjustment gap and abuts against the cell assembly 1. The first end plate 4 and the second end plate 5 at both ends of the cell assembly 1 are fastened by the pretensioning band 2. The adjustment gap formed between the second end plate 5 and the cell assembly 1 provides space for the displacement of the piston of the cylinder 3. Throughout the entire life cycle, as the cycle progresses or aging deepens, the thickness of the cell assembly 1 gradually increases, so the pretensioning force of the pretensioning band 2 gradually increases. At this time, the cylinder 3 drives the piston to retract to release the excessive pressure applied by the pretensioning band 2, avoiding damage to the cell assembly 1 caused by excessive pretensioning force.

[0018] like Figure 1 As shown, the piston end of the cylinder 3 is provided with a pressure plate 6, and the area of ​​the pressure plate 6 is consistent with the area of ​​the end of the battery cell assembly 1 facing the pressure plate 6. This ensures that the pressure applied by the cylinder 3 is evenly distributed across the entire end face of the battery cell assembly 1, avoiding local stress concentration that could damage the battery cell structure, while also improving the control accuracy of the preload force.

[0019] like Figure 2As shown, it also includes a housing (not shown in the figure). The battery cell assembly 1, pretension band 2, first end plate 4, and second end plate 5 are all located inside the housing. The cylinder 3 is connected to a high-pressure gas cylinder 8 via an air pipe 7. The air pipe 7 is equipped with an exhaust valve 9, an intake valve 10, and a pressure sensor 11. The intake end of the intake valve 10 is connected to the high-pressure gas cylinder 8, and the outlet end of the intake valve 10 is connected to the cylinder 3. The intake end of the exhaust valve 9 is connected to the cylinder 3, and the outlet end of the exhaust valve 9 is connected to the inside of the housing, or the outlet end of the exhaust valve 9 is connected to the outside of the housing. The pressure sensor 11 is used to collect the pressure of the cylinder 3. The air pressure acquisition device 11 collects the air pressure of cylinder 3. Cylinder 3 is connected to the battery cell assembly 1 via a pressure plate 6 at the piston end. The pressure of cylinder 3 is the pre-tightening pressure of battery cell assembly 1. If the thickness of the battery cell increases, the pre-tightening pressure increases. When the air pressure acquisition device 11 receives a signal, the exhaust valve 9 opens, releasing a certain amount of gas from cylinder 3 into or outside the battery pack (casing). The piston end of cylinder 3 retracts, restoring the pressure of cylinder 3 to the normal range. When the exhaust valve 9 releases a certain amount of gas from cylinder 3 into the casing, the volume inside the battery pack is relatively large compared to cylinder 3, and the amount of gas released from cylinder 3 is insufficient to significantly affect the internal air pressure of the battery pack. When the exhaust valve 9 releases a certain amount of gas from cylinder 3 outside the casing, the frame needs to be equipped with an exhaust opening. The air pressure acquisition device 11 collects air pressure information and transmits it to the battery management system (BMS) via electrical signals to achieve real-time pressure monitoring. After recognizing the pressure signal, it outputs a pressurization or depressurization signal to the intake valve 10 or the exhaust valve 9, thereby adjusting the pre-tightening pressure on the battery pack by regulating the air pressure in the cylinder 3. The exhaust valve 9 is an intake precision proportional valve and the exhaust valve 9 is an outlet precision proportional valve. The air pressure acquisition device 11 has a signal output function.

[0020] In this embodiment, the moving distance of the piston end of the cylinder 3 is 1% to 10% of the thickness of the battery cell assembly 1. The thickness of the battery cell assembly 1 is defined as the dimension of the battery cell assembly 1 along the piston axis of the cylinder 3. Limiting the moving distance of the piston end of the cylinder 3 can effectively compensate for the dimensional changes caused by the expansion of the battery cell, and avoid the cylinder 3 becoming too large or the adjustment response lagging due to excessive piston end stroke, thus ensuring a balance between the compactness of the module structure and the adjustment efficiency.

[0021] like Figure 1 As shown, the high-pressure gas cylinder 8 is installed at the bottom of the housing and is located below the cylinder 3. The high-pressure gas cylinder 8 and the cylinder 3 are connected by the gas pipe 7 along the inner wall of the housing. The cylinder 3 is installed on the second end plate 5 with screws, and the high-pressure gas cylinder 8 is located below the cylinder 3, thereby saving module space and facilitating the arrangement of the gas path.

[0022] In this embodiment, the gas stored in the high-pressure gas cylinder 8 is an inert gas, specifically nitrogen or argon, and the pressure resistance of the high-pressure gas cylinder 8 is greater than 2 MPa. Using an inert gas (nitrogen / argon) prevents the gas system from igniting due to gas leakage or high temperatures, thus improving safety. The design of the high-pressure gas cylinder 8 with a pressure resistance greater than 2 MPa ensures a stable gas supply capacity for the cylinder 3 under high-pressure conditions.

[0023] like Figure 2 As shown, the exhaust valve 9 is equipped with a muffler 12 at its outlet to reduce exhaust noise. This muffler 12 is existing technology.

[0024] like Figure 1 As shown, the pretensioning band 2 consists of multiple parallel steel strips evenly distributed along the circumference of the first end plate 4 and the second end plate 5. This design of evenly distributed parallel steel strips ensures that the pretensioning force is uniformly transmitted along the circumference of the first end plate 4 and the second end plate 5, preventing uneven force distribution at a single point from causing end plate deformation or tilting of the battery cell assembly 1, thus improving the overall structural stability.

[0025] It is understood that the specific embodiments described above are merely for explaining the relevant utility model and not for limiting the utility model. It should also be noted that, for ease of description, only the parts related to the utility model are shown in the accompanying drawings. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contradict or conflict with each other. All equivalent structural transformations made based on the content of this utility model specification and drawings, directly or indirectly applied to other related technical fields, are similarly included within the protection scope of this utility model.

Claims

1. A battery pack, characterized by, The device includes a battery cell assembly, a pre-tensioning band, a cylinder, a first end plate, and a second end plate. The first end plate abuts against one end of the battery cell assembly, and the second end plate is spaced apart from the other end of the battery cell assembly to form an adjustment gap. The pre-tensioning band is wrapped around the outer peripheral walls of the first and second end plates. The housing of the cylinder is fixedly installed on the second end plate, and the piston end of the cylinder passes through the adjustment gap and abuts against the battery cell assembly.

2. The battery pack according to claim 1, characterized in that, The piston end of the cylinder is provided with a pressure plate, and the area of ​​the pressure plate is consistent with the area of ​​the battery cell assembly facing the pressure plate.

3. The battery pack according to claim 1, characterized in that, It also includes a housing, and the battery cell assembly, pretension band, first end plate, and second end plate are all located inside the housing. The cylinder is connected to a high-pressure gas cylinder via an air pipe. The air pipe is equipped with an exhaust valve, an intake valve, and a pressure acquisition device. The intake end of the intake valve is connected to the high-pressure gas cylinder, and the outlet end of the intake valve is connected to the cylinder. The intake end of the exhaust valve is connected to the cylinder, and the outlet end of the exhaust valve is connected to the inside of the housing, or the outlet end of the exhaust valve is connected to the outside of the housing. The pressure acquisition device is used to collect the air pressure of the cylinder.

4. The battery pack according to claim 1, characterized in that, The moving distance of the piston end of the cylinder is 1% to 10% of the thickness of the battery cell assembly.

5. The battery pack according to claim 3, characterized in that, The high-pressure gas cylinder is installed at the bottom of the housing and is located below the cylinder. The high-pressure gas cylinder and the cylinder are connected by the gas pipe along the inner wall of the housing.

6. The battery pack according to claim 3, characterized in that, The gas stored in the high-pressure gas cylinder is an inert gas, which is either nitrogen or argon, and the pressure resistance of the high-pressure gas cylinder is greater than 2 MPa.

7. The battery pack according to claim 3, characterized in that, The exhaust valve outlet is equipped with a muffler to reduce exhaust noise.

8. The battery pack according to claim 1, characterized in that, The pretensioning band consists of multiple parallel steel strips, which are evenly distributed circumferentially along the first and second end plates.

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