Device for measuring charge-discharge expansion displacement of battery cell by using fixing force

Abstract

The utility model discloses a device for measuring charging and discharging expansion displacement of a battery cell by using fixing force, which comprises a bottom plate, a fixed plate, a movable frame, a pressure sensor, a pressure generating device, a movable pressing plate, a displacement sensor and the like, according to the device provided by the utility model, constant pressure can be applied to the battery cell through the pressure generating device and the pressure sensor, during testing, the distance change between the horizontal plate and the movable pressing plate is measured through the compression amount of the detection end of the displacement sensor, and the distance change is the thickness change of the battery cell, namely the expansion displacement amount of the battery cell. The device provided by the utility model can be used for testing the expansion displacement of the battery cell under the condition that constant pressure is applied to the battery cell, an assembly mode beneficial to prolonging the service life of the battery cell can be selected through a plurality of sample tests, and data support is provided for battery system product development.

Description

Technical Field

[0001] This utility model belongs to the field of battery charging testing, specifically relating to a device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force. Background Technology

[0002] As the power source for new energy vehicles, lithium-ion batteries experience increased internal expansion pressure during charging and discharging due to the coupled effects of stress changes caused by lithium insertion / extraction, thermal expansion, and lithium plating. Furthermore, the cells expand during charging and contract during discharging; this phenomenon is commonly known as battery breathing.

[0003] To demonstrate that breathing space directly affects cell lifespan degradation, PP and foam spacers were used to assemble modules between cells for cycle life testing. PP spacers were considered to have no breathing space, while foam spacers were considered to have breathing space. Under the same pressure and testing conditions, after 1200 cycles, the foam spacer module retained approximately 90% of its capacity, while the PP spacer module retained approximately 76%. This demonstrates that breathing space has a significant impact on cell lifespan. However, spacer contraction and expansion are inherent characteristics of the product and cannot be precisely controlled, thus lacking sufficient data support.

[0004] Conventional expansion force testing typically involves limiting the expansion displacement of the battery cell to test the expansion force generated by the cell itself, or installing a pressure sensor in the module to test the actual expansion of the battery cell. Both of these testing methods test the actual expansion force generated by the battery cell, and cannot apply constant pressure to the battery cell to test the expansion displacement. Furthermore, they cannot measure the impact of different expansion displacements caused by different pressures on the battery cell life test results, and cannot provide more data for separator selection. Summary of the Invention

[0005] Therefore, the technical problem to be solved by this patent is to overcome the fact that there is currently no tooling that can test the expansion displacement of the battery cell under constant pressure. It can select the assembly method that is beneficial to the extension of battery cell life through multiple sample tests, and provide data support for the development of battery system products.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] A device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force, comprising:

[0008] The base plate is used to place the battery cells;

[0009] A fixing plate is fixed vertically above the base plate and arranged parallel to the base plate;

[0010] The movable frame is located between the base plate and the fixed plate and can move vertically relative to the base plate.

[0011] The pressure sensor is fixed to the top of the movable frame, with the sensing end of the pressure sensor facing upwards;

[0012] A pressure generating device is fixed on a fixed plate, and the actuator of the pressure generating device abuts against the detection end of the pressure sensor; preferably, the pressure generating device is a hydraulic cylinder;

[0013] The movable pressure plate is located between the base plate and the movable frame, and can move vertically relative to the base plate.

[0014] A displacement sensor is fixed above the movable pressure plate, with its detection end abutting against the top surface of the movable pressure plate.

[0015] In a further embodiment, the displacement sensor is fixed above the movable pressure plate by a displacement reference frame. The displacement reference frame includes support legs vertically fixed to the base plate and a horizontal plate fixed to the top of the support legs. The displacement sensor is fixed to the horizontal plate. Fixing the displacement sensor to the horizontal plate of the displacement reference frame facilitates the installation and positioning of the displacement sensor.

[0016] In a further embodiment, the displacement sensor is fixed to a horizontal plate using a mounting plate, an elastic sheet, and bolts. The mounting plate is fixed to the horizontal plate. The two opposite sidewalls of the displacement sensor have grooves extending along the Z-axis. Each end of the elastic sheet has an elastic hook that can be inserted into the groove; the elastic hooks have serrations. Through holes are provided at both ends of the elastic sheet, and threaded blind holes are provided on the mounting plate. Bolts passing through the through holes and threaded blind holes can fix the elastic sheet to the mounting plate, and the serrations press the displacement sensor firmly, thus fixing the displacement sensor to the horizontal plate. This embodiment, by using a mounting plate, elastic sheet, and bolts to fix the displacement sensor to the horizontal plate, facilitates the assembly of the displacement sensor.

[0017] In a further embodiment, a helical spring is fitted around the displacement sensor. The bottom of the helical spring is fixed to the top of the movable pressure plate, and the top of the helical spring is fixed to the bottom of the movable frame. The helical spring provides a uniform upward thrust to the movable pressure plate, thereby ensuring that the compression of the displacement sensor detection end at each position is balanced.

[0018] In a further embodiment, the base plate and the fixing plate are fixedly connected by several vertically arranged cylindrical shafts. The base plate is fixed to the bottom of the cylindrical shafts, and the fixing plate is fixed to the top of the cylindrical shafts. Connecting the base plate and the fixing plate together by cylindrical shafts can improve the overall stability of the device, and the structure is simple and easy to manufacture.

[0019] In a further embodiment, the movable frame includes an upper sliding plate and a lower sliding plate arranged parallel to the base plate, and a first linear bearing for connecting the upper and lower sliding plates; the upper sliding plate, the lower sliding plate, and the first linear bearing are all sleeved on a cylindrical shaft and slidably connected to the cylindrical shaft. The first linear bearing, in cooperation with the cylindrical shaft, provides precise linear guidance for the movement of the movable frame.

[0020] In a further embodiment, the movable pressure plate has a mounting hole, in which a second linear bearing is fixed. The movable pressure plate is slidably connected to the cylindrical shaft through the second linear bearing. The second linear bearing is sleeved outside the cylindrical shaft, and through the cooperation between the second linear bearing and the cylindrical shaft, precise linear guidance is provided for the movement of the movable pressure plate.

[0021] This utility model has the following beneficial effects:

[0022] This invention provides a device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force. The device includes a base plate, a fixed plate, a movable frame, a pressure sensor, a pressure generating device, a movable pressure plate, and a displacement sensor. The device applies a constant pressure to the battery cell using the pressure generating device and the pressure sensor. During testing, the change in distance between the horizontal plate and the movable pressure plate is measured by detecting the compression at the displacement sensor's detection end. This distance change represents the change in the battery cell's thickness, i.e., the expansion displacement. This device can test the expansion displacement of a battery cell under constant pressure. Multiple sample tests can be used to select an assembly method that extends battery cell life, providing data support for battery system product development. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of this patent or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this patent. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 A schematic diagram of the overall device provided by this utility model (without battery cells placed);

[0025] Figure 2 for Figure 1 Enlarged diagram of section A in the middle;

[0026] Figure 3 A schematic diagram showing the installation of the mounting plate, elastic sheet, and bolts;

[0027] Figure 4 A schematic diagram of the overall device provided by this utility model (when placing the battery cell);

[0028] Explanation of reference numerals in the attached drawings: 1-Base plate; 2-Modible pressure plate; 21-Mounting hole; 3-Modible frame; 31-Upper slide plate; 32-First linear bearing; 33-Lower slide plate; 4-Helical spring; 5-Pressure generating device; 6-Fixed plate; 7-Pressure sensor; 8-Displacement sensor; 81-Groove; 9-Displacement reference frame; 91-Horizontal plate; 92-Support foot; 10-Cylindrical shaft; 20-Second linear bearing; 30-Battery cell; 911-Mounting plate; 911a-Threaded blind hole; 40-Elastic sheet; 401-Elastic hook; 402-Serge serration; 403-Through hole; 50-Bolt. Detailed Implementation

[0029] The technical solution of this patent will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this patent, not all of them. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this patent.

[0030] In the description of this patent, it should be noted that the terms "upper," "lower," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this patent and for simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. "Sliding connection" refers to two parts connected together and capable of relative movement. For those skilled in the art, the specific meaning of the above terms in this patent can be understood according to the specific circumstances.

[0032] Furthermore, the technical features involved in the different embodiments of this patent described below can be combined with each other as long as they do not conflict with each other.

[0033] refer to Figures 1 to 4This patent provides a device for measuring the expansion displacement of a lithium battery during charging and discharging using a fixed force, comprising a base plate 1, a cylindrical shaft 10, a movable pressure plate 2, a movable frame 3, several helical springs 4, a pressure generating device 5, a fixed plate 6, a pressure sensor 7, several displacement sensors 8, and a displacement reference frame 9.

[0034] All cylindrical shafts 10 are fixed at their upper and lower ends to the fixed plate 6 and the base plate 1, respectively. The movable frame 3 and the movable pressure plate 2 are slidably connected to the cylindrical shafts 10. The movable pressure plate 2 is located between the movable frame 3 and the base plate 1. The displacement reference frame 9 includes a horizontal plate 91 and a support foot 92. The bottom end of the support foot 92 is fixed to the base plate 1, and the horizontal plate 91 is fixed to the top end of the support foot 92. The movable frame 3 is located below the fixed plate 6. The non-detection ends of several displacement sensors 8 are fixed to the horizontal plate 91. The detection ends of the displacement sensors 8 face downwards. The displacement sensors 8 pass through the horizontal plate 91 and the bottom of the movable frame 3 from top to bottom. The detection ends of the displacement sensors 8 abut against the top surface of the movable pressure plate 2. A pressure sensor 7 is fixed to the top surface of the movable frame 3. The detection end of the pressure sensor 7 faces upwards. A pressure generating device 5 is fixed on the fixed plate 6. The actuator of the pressure generating device 5 can pass downwards through the fixed plate 6. The actuator of the pressure generating device 5 can abut against the detection end of the pressure sensor 7.

[0035] During testing, the battery cell 30 is first placed between the movable pressure plate 2 and the base plate 1 (so that the thickness direction of the cell 30 is aligned with the Z-axis direction). Then, the pressure generating device 5 is turned on, causing the actuator of the pressure generating device 5 to extend downward and press against the detection end of the pressure sensor 7, applying pressure to the detection end of the pressure sensor 7. This causes the movable frame 3 to slide down. When the cell 30 is placed under the movable pressure plate 2, since the movable pressure plate 2 is slidably mounted on the cylindrical shaft 10, the movable pressure plate 2 passively slides upward, causing the detection end of the displacement sensor 8 to retract. Then, the battery cell 30 is charged and discharged. The battery cell 30 expands in the thickness direction (Z-axis direction), causing the movable pressure plate 2 to slide further upward. The detection end of the displacement sensor 8 further contracts. After the movable pressure plate 2 slides upward to a certain extent, it abuts against the upper movable frame 3, driving the movable frame 3 to rise. This reaction acts on the pressure generating device 5. The change in distance between the horizontal plate 91 and the movable pressure plate 2 is measured by the compression amount detected by the displacement sensor 8. This change in distance is the change in the thickness of the battery cell 30, which is the expansion displacement of the battery cell 30.

[0036] Several evenly distributed helical springs 4 are arranged between the bottom of the movable pressure plate 2 and the movable frame 3. The bottom end of the helical springs 4 is fixed to the top surface of the movable pressure plate 2, and the helical springs 4 are sleeved on the outside of the displacement sensor 8. In this patent, the main function of the helical springs 4 is to provide a uniform upward thrust for the movable pressure plate 2. Because the uneven expansion of the surfaces of the battery cell 30 during charging and discharging can cause the movable pressure plate 2 to tilt when sliding upward, the helical springs 4 effectively compensate for this uneven expansion defect, so that the movable pressure plate 2 moves horizontally upward when it moves upward, ensuring that the compression of the detection end of the displacement sensor 8 at each position is balanced.

[0037] For example, before testing, cell 30 has a preload of 100kN, and the initial pressure of pressure generating device 5 is set to 100kN. Thus, the initial pressure of pressure generating device 5 replaces the cell's preload. After the battery undergoes charge-discharge cycles, it generates a 10kN expansion force. Pressure generating device 5 still maintains a 100kN thrust. Cell 30, through movable pressure plate 2 and spring, pushes movable frame 3 upward, pushing pressure sensor and hydraulic cylinder upward. This continues until cell 30 expands and the expansion pressure decreases, stopping when a 100kN thrust is maintained between movable pressure plate 2 and cell 30. Measuring the displacement change between movable pressure plate 2 and horizontal plate 91 at this point represents the thickness change of cell 30, i.e., the expansion displacement.

[0038] In order to test battery cells 30 of different thicknesses, the displacement sensor 8 can be adjusted in position along the Z-axis on the horizontal plate 91. When it is necessary to test a thicker battery cell 30, the position of the displacement sensor 8 can be raised, and when it is necessary to test a thinner battery cell 30, the position of the displacement sensor 8 can be lowered.

[0039] The displacement sensor 8 is fixed to the horizontal plate 91 by a mounting plate 911, an elastic sheet 40, and bolts 50. Specifically, the mounting plate 911 is fixed to the horizontal plate 91. The displacement sensor 8 has two opposing sidewalls with grooves 81 extending along the Z-axis. Each end of the elastic sheet 40 has an elastic hook 401, which can be inserted into the two grooves 81 respectively. Each elastic sheet 40 has through holes 403 at both ends. The mounting plate 911 has threaded blind holes 911a. The elastic hooks 401 of the elastic sheet 40 extend into the grooves 81. The bolts 50 pass through the through holes 403 and then into the threaded blind holes 911a, with the tail of the bolts 50 threadedly connected to the threaded blind holes 911a. The elastic hooks 401 have serrations 402. When the bolts 50 are tightened, the serrations 402 will press the displacement sensor 8 tightly.

[0040] Specifically, the movable frame 3 includes an upper sliding plate 31, four first linear bearings 32, and a lower sliding plate 33. Each cylindrical shaft 10 has a corresponding first linear bearing 32 fitted on its exterior. The upper end of each first linear bearing 32 is fixed to the upper sliding plate 31, and the lower end of each first linear bearing 32 is fixed to the lower sliding plate 33. The first linear bearings 32 cooperate with the cylindrical shafts 10 to provide precise linear guidance for the movement of the movable frame 3.

[0041] Mounting holes 21 are provided at the four corners of the movable pressure plate 2. A second linear bearing 20 is fixed in each mounting hole 21. The second linear bearing 20 is sleeved outside the cylindrical shaft 10. The second linear bearing 20 and the cylindrical shaft 10 cooperate with each other to provide precise linear guidance for the movement of the movable pressure plate 2.

[0042] The pressure generating device 5 in this patent can be a hydraulic cylinder.

[0043] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this patent.

Claims

1. A device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force, characterized in that, include: Base plate; A fixing plate is fixed vertically above the base plate and arranged parallel to the base plate; The movable frame is located between the base plate and the fixed plate and can move vertically relative to the base plate; A pressure sensor is fixed to the top of the movable frame, with the sensing end of the pressure sensor facing upwards; A pressure generating device is fixed on a fixed plate, and the actuator of the pressure generating device abuts against the detection end of the pressure sensor; A movable pressure plate is located between the base plate and the movable frame, and can move vertically relative to the base plate; A displacement sensor is fixed above the movable pressure plate, with its detection end abutting against the top surface of the movable pressure plate.

2. The device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force according to claim 1, characterized in that, The displacement sensor is fixed above the movable pressure plate by a displacement reference frame. The displacement reference frame includes a support foot that is vertically fixed to the base plate and a horizontal plate that is fixed to the top of the support foot. The displacement sensor is fixed on the horizontal plate.

3. The device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force according to claim 2, characterized in that, The displacement sensor is fixed to a horizontal plate by a mounting plate, an elastic sheet, and bolts. The mounting plate is fixed to the horizontal plate. The two opposite sidewalls of the displacement sensor have grooves extending along the Z-axis. Each end of the elastic sheet has an elastic hook that can be inserted into the groove. The elastic hook has serrations. Both ends of the elastic sheet are provided with through holes. The mounting plate is provided with threaded blind holes. The elastic sheet can be fixed to the mounting plate by bolts passing through the through holes and threaded blind holes, and the displacement sensor can be pressed and fixed by the serrations.

4. The device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force according to claim 1, characterized in that, The displacement sensor is fitted with a helical spring, the bottom of which is fixed to the top of the movable pressure plate, and the top of which is fixed to the bottom of the movable frame.

5. A device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force, as described in any one of claims 1 to 4, characterized in that, The base plate and the fixing plate are fixedly connected by a plurality of vertically arranged cylindrical shafts. The base plate is fixed to the bottom of the cylindrical shafts, and the fixing plate is fixed to the top of the cylindrical shafts.

6. The device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force according to claim 5, characterized in that, The movable frame includes an upper sliding plate and a lower sliding plate arranged parallel to the base plate, and a first linear bearing for connecting the upper sliding plate and the lower sliding plate; the upper sliding plate, the lower sliding plate and the first linear bearing are all sleeved on the cylindrical shaft and slidably connected to the cylindrical shaft.

7. The device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force according to claim 5, characterized in that, The movable pressure plate has a mounting hole, and a second linear bearing is fixed in the mounting hole. The movable pressure plate is slidably connected to the cylindrical shaft through the second linear bearing.

8. A device for measuring the expansion displacement of a battery cell during charging and discharging using a fixed force, as described in any one of claims 1 to 4, characterized in that, The pressure generating device is a hydraulic cylinder.

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