Battery pack connecting structure and connecting method

Abstract

The invention provides a battery pack connecting structure and a connecting method.The connecting structure is used for fixing a lower shell and an upper box cover of a battery pack and comprises a bolt, a sleeve, a first nut and a second nut, a first through hole is formed in the lower shell, a second through hole is formed in the upper box cover, one end of the bolt is used for penetrating through the first through hole and the second through hole, and the other end of the bolt is used for penetrating through the sleeve. The first nut and the second nut are locked; the bolt is sleeved with the sleeve, and the sleeve is configured to be capable of being melted so as to be embedded into the bolt. The sleeve is sleeved with the second nut; a melting hole is formed in the side wall of the second nut and used for allowing a laser beam to enter so that the laser beam can melt the sleeve. The bolt is matched with the first nut and the second nut so that the lower shell and the upper box cover can be pressed together, meanwhile, the sleeve is melted when the bolt is pushed into the sleeve through heat generated by friction of the bolt and heating of laser beams, the sleeve is embedded into the bolt, the first nut and the second nut, and the strength and stability of connection between the lower shell and the upper box cover are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery packs, and in particular to a battery pack connection structure and a connection method. Background Art

[0002] All-aluminum battery packs are widely used in current pure electric vehicles due to their relatively light weight and relatively high strength. They provide energy and store energy for vehicle operation. The all-aluminum battery pack mainly includes a lower shell and an upper box cover. The battery cell module, tray and 200MS integrated components are integrated in the lower shell. The upper box cover is closed on the lower shell and sealed and fixed to form a complete battery.

[0003] In the prior art, there are two main ways to fix the lower shell and the upper box cover. One is to fix the upper box cover to the lower shell by welding. Although the connection strength is relatively high and stable, welding is prone to deformation and high temperature is easily generated during welding. Therefore, a connecting skirt needs to be set to increase the stability of welding, which significantly increases the cost and welding difficulty. In addition, when using the welding fixing method, if the battery cell module needs to be replaced, the battery box needs to be replaced at the same time, which makes the later maintenance cost high. Another way to fix the lower shell and the upper box cover is to fix them by traditional bolt matching. However, since the battery tray needs to carry a heavy battery cell module, the bolts connecting the lower shell and the upper box cover need to withstand a large impact force, making the bolt connection unstable. At this time, additional anti-loosening measures need to be set, such as using a latch or a series steel wire to achieve the purpose of anti-loosening. However, in actual use, it is still easy to cause a gap between the lower shell and the upper box cover due to slight loosening, which increases the relative displacement between the lower shell and the upper box cover, posing a safety hazard. Therefore, how to improve the connection stability of the battery pack while maintaining relatively low maintenance costs is an urgent problem that needs to be solved. Summary of the invention

[0004] One of the purposes of the present invention is to provide a battery pack connection structure and connection method to solve the problem of unstable connection between the lower shell and the upper box cover of the battery pack in the prior art, so as to reduce the maintenance cost of the battery pack.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A battery pack connection structure, used to fix the lower shell and upper cover of the battery pack to each other, comprising:

[0007] A bolt, a sleeve and a first nut and a second nut, a first through hole is formed on the lower shell body, a second through hole is formed on the upper box cover, one end of the bolt passes through the first through hole and the second through hole, and is locked with the first nut; the sleeve is sleeved on the bolt, and one end abuts against the first nut, and the sleeve is configured to be melted to fit with the bolt; the second nut is sleeved on the sleeve, and one end abuts against the first nut; a melting hole is formed on the side wall of the second nut, and the melting hole is used for the laser beam to be injected so that the laser beam can melt the sleeve.

[0008] According to the above technical means, the bolt and the first nut and the second nut cooperate with each other to press the lower shell and the upper box cover together. At the same time, the friction heat generated by the bolt and the laser beam heating are used to melt the sleeve when the bolt is pushed into the sleeve, so that the sleeve can be quickly melted and engaged with the bolt, the first nut and the second nut, thereby preventing the bolt, the first nut and the second nut from loosening and causing the connection between the lower shell and the upper box cover to loosen, thereby increasing the strength and stability of the connection between the lower shell and the upper box cover, reducing the maintenance frequency, and reducing the maintenance cost.

[0009] Furthermore, a first threaded portion, a friction portion and a second threaded portion are sequentially formed on the bolt, the friction portion is used to rub the sleeve to melt the inner wall of the sleeve; the first threaded portion is used to engage with the melted inner wall of the sleeve; the second threaded portion is formed at one end of the bolt close to the first nut, and is used to lock with the first nut.

[0010] According to the above-mentioned technical means, the friction portion can make the bolt generate sufficient friction with the sleeve during the screwing process, which is beneficial to the melting of the sleeve. The first threaded portion is embedded in the melted sleeve to form a tight and firm connection, so that the entire connection structure can withstand strong tensile and shear forces, thereby improving the stability of the connection between the lower shell and the upper box cover; the second threaded portion and the first nut are locked together, and the installation is simple and quick.

[0011] Furthermore, the first threaded portion includes a first thread segment and a second thread segment, and the first thread segment and the second thread segment have opposite thread directions.

[0012] According to the above technical means, since the first thread segment and the second thread segment have opposite thread rotation directions, when the bolt is engaged with the melted sleeve, they can respectively generate opposite torque effects on the cooled inner wall of the sleeve, which is beneficial to further tighten the connection between the bolt and the sleeve, thereby improving the stability of the connection.

[0013] Furthermore, a limiting portion is formed on the outer side wall of the other end of the sleeve, and after the sleeve passes through the first through hole and the second through hole, the limiting portion abuts against the lower shell or the upper box cover.

[0014] According to the above technical means, the limiting portion provides stable support and limiting for the sleeve, ensuring that the sleeve can limit its position after passing through the first through hole and the second through hole, which is beneficial to prevent the sleeve from shifting during subsequent assembly or use, and increases the installation accuracy of the sleeve.

[0015] Furthermore, it also includes a heating ring, which is embedded in the inner side of the second nut, and the laser beam can heat the heating ring through the melting hole, and further melt the limiting part through the heating ring.

[0016] According to the above technical means, the laser beam heats the heating ring to evenly transfer heat to the sleeve through the heating ring, which is beneficial to reducing thermal stress concentration and deformation when the laser beam melts the sleeve, thereby improving the melting efficiency; and the heating ring can also prevent the melted sleeve from leaking and flowing out of the melting hole, thereby ensuring the integrity of the sleeve.

[0017] Furthermore, the sleeve is made of aluminum alloy; the heating ring is made of one of tungsten, ceramic, and titanium alloy, so that the melting point of the heating ring is higher than that of the sleeve.

[0018] According to the above technical means, the melting point of the heating ring is higher than that of the sleeve. During the laser beam heating process, the heating ring can remain in a solid state and will not melt or deform due to high temperature, thereby ensuring that the heating ring maintains stability and reliability during the melting process of the sleeve and preventing the loss of the melted sleeve.

[0019] The present invention also provides a connection method based on the above battery pack connection structure, comprising the following steps:

[0020] S1, fit the first through hole of the lower shell and the second through hole of the upper cover, and pass the sleeve embedded with the heating ring through the first through hole and the second through hole, so that the limiting part abuts against the lower shell or the upper cover;

[0021] S2, preheating: applying torque and thrust to the bolt synchronously, rotating and pushing the bolt into the sleeve, and making the friction part rub against the inner wall of the sleeve to melt the inner wall of the sleeve by frictional heat generation; at the same time, emitting a laser beam into the melting hole to heat the heating ring, further making the heating ring transfer heat to the limiting part, so that the limiting part begins to melt;

[0022] S3, filling: reducing the power of the laser beam, increasing the torque and thrust on the bolt, so that the bolt moves to the melted limiting portion, and squeezes the melted limiting portion to fill the first through hole and / or the second through hole;

[0023] S4, tightening: when the spacing between the second threaded portion and the first nut is 2 mm to 5 mm, while keeping the bolt able to continue to be pushed into the sleeve, the thrust applied to the bolt is rapidly reduced, and the rotation speed of the bolt and the power of the laser beam are reduced until the second threaded portion and the first nut are locked with each other.

[0024] According to the above technical means, the inner wall of the sleeve and the limiting portion are quickly melted by combining frictional heat generation and laser beam heating. When the bolt is screwed into the sleeve, the melted sleeve can be squeezed into the first through hole, the second through hole and the gap between the second nut and the sleeve, thereby enhancing the strength and stability of the connection between the lower shell and the upper box cover. At the same time, after the melted limiting portion is filled into the first through hole and the second through hole, a tight sealing structure can be formed between the lower shell and the upper box cover, which is beneficial to prevent leakage of liquid or gas inside the battery pack and improve the safety and reliability of the battery pack.

[0025] Furthermore, in the step S2, the rotation speed of the bolt is 4500 r / min to 9000 r / min, the thrust applied to the bolt is 1500 N to 3500 N, and the power of the laser beam is 2000 W to 4800 W.

[0026] According to the above technical means, the rotation speed and thrust of the bolt act together on the inner wall of the sleeve, and the sleeve is quickly melted by frictional heat generation. Within the set rotation speed and thrust range, it can ensure that the heat generated by friction is sufficient to melt the inner wall of the sleeve, while avoiding material splashing or deformation caused by overheating; within the power range of 2000W to 4800W, the laser beam can be efficiently transmitted to the heating ring and the sleeve, thereby achieving rapid and uniform melting of the sleeve.

[0027] Furthermore, in step S3, the bolt rotation speed is 6000r / min~10000r / min, which is more than 20% higher than that in step S2; the thrust applied to the bolt is 1800N~5000N; the power of the laser beam is not less than 1600W, which is 10%~20% lower than that in step S2.

[0028] According to the above-mentioned technical means, increasing the rotation speed of the bolt can speed up the advancement speed of the bolt in the sleeve, so that the melted limiting portion can be more fully filled into the first through hole and the second through hole under the extrusion action of the bolt, which is beneficial to reduce the problem of insufficient filling or gap caused by cooling and solidification of the sleeve, and ensure the strength and reliability of the connection.

[0029] Furthermore, in the step S4, when the spacing between the second threaded portion and the first nut is 2 mm to 5 mm, the rotation speed of the bolt is reduced to 60 r / min to 200 r / min, and the power of the laser beam is reduced to 600 W to 800 W until the second threaded portion is locked with the first nut.

[0030] According to the above technical means, reducing the rotation speed of the bolt is conducive to reducing the vibration and impact force generated by high-speed rotation, making the engagement between the bolt and the sleeve smoother and tighter, helping to avoid loosening or damage of the thread due to vibration, thereby improving the quality of thread locking.

[0031] The beneficial effects of the present invention are:

[0032] 1. The bolt and the first nut and the second nut cooperate with each other to press the lower shell and the upper box cover together. At the same time, the sleeve is melted by utilizing the friction heat of the bolt and the heating of the laser beam when the bolt is pushed into the sleeve, so that the sleeve can be quickly melted and then engaged with the bolt, the first nut and the second nut, thereby preventing the bolt, the first nut and the second nut from loosening and causing the connection between the lower shell and the upper box cover to loosen, thereby increasing the strength and stability of the connection between the lower shell and the upper box cover, reducing the maintenance frequency, and reducing the maintenance cost.

[0033] 2. By utilizing a combination of frictional heat generation and laser beam heating, the inner wall of the sleeve and the limiting portion are quickly melted, so that when the bolt is screwed and pushed into the sleeve, the melted sleeve can be squeezed into the first through hole, the second through hole and the gap between the second nut and the sleeve, thereby enhancing the strength and stability of the connection between the lower shell and the upper box cover; at the same time, after the melted limiting portion is filled into the first through hole and the second through hole, a tight sealing structure can be formed between the lower shell and the upper box cover, which is beneficial to prevent leakage of liquid or gas inside the battery pack and improve the safety and reliability of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 is a schematic diagram of the overall structure of the connection structure in an embodiment of the present invention;

[0036] Figure 2 is a schematic diagram of the structure of a bolt in an embodiment of the present invention;

[0037] Figure 3 is a schematic diagram of the structure of the bolt being initially rotated and pushed into the sleeve in an embodiment of the present invention;

[0038] Figure 4 is a schematic diagram of the structure in which a bolt is rotated and pushed into the middle of a sleeve in an embodiment of the present invention;

[0039] Figure 5 is a schematic diagram of a structure in which a bolt and a second nut are locked in an embodiment of the present invention;

[0040] Figure 6 1 is a step diagram of a battery pack connection method in an embodiment of the present invention. Description of the drawings:

[0042] 100, lower shell; 200, upper box cover; 300, bolt; 310, first threaded portion; 311, first threaded section; 312, second threaded section; 320, friction portion; 330, second threaded portion; 340, nut; 400, sleeve; 410, limit portion; 500, first nut; 600, second nut; 610, melting hole; 700, heating ring. DETAILED DESCRIPTION

[0043] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. The accompanying drawings are only used for exemplary description and cannot be understood as limiting the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0044] like Figures 1 to 5 As shown, this embodiment provides a battery pack connection structure for fixing the lower shell 100 and the upper box cover 200 of the battery pack to each other, including:

[0045] Bolt 300, sleeve 400 and first nut 500 and second nut 600, a first through hole is formed on the lower shell 100, and a second through hole is formed on the upper box cover 200, one end of the bolt 300 is used to penetrate the first through hole and the second through hole, and be locked with the first nut 500; the sleeve 400 is sleeved on the bolt 300, and one end abuts against the first nut 500, the sleeve 400 is configured to be melted to fit with the bolt 300; the second nut 600 is sleeved on the sleeve 400, and one end abuts against the first nut 500; the side wall of the second nut 600 is formed with a melting hole 610, and the melting hole 610 is used for the laser beam to be injected so that the laser beam can melt the sleeve 400.

[0046] The bolt 300 and the first nut 500 and the second nut 600 cooperate with each other to press the lower shell 100 and the upper box cover 200 together. At the same time, the friction heat generated by the bolt 300 and the laser beam heating are used to melt the sleeve 400 when the bolt 300 is pushed into the sleeve 400, so that the sleeve 400 can be quickly melted and interlocked with the bolt 300, the first nut 500 and the second nut 600, thereby preventing the bolt 300, the first nut 500 and the second nut 600 from loosening and causing the connection between the lower shell 100 and the upper box cover 200 to loosen, thereby increasing the strength and stability of the connection between the lower shell 100 and the upper box cover 200, reducing the maintenance frequency, and reducing the maintenance cost.

[0047] like Figure 2 As shown, in this embodiment, the bolt 300 is sequentially formed with a first threaded portion 310, a friction portion 320 and a second threaded portion 330. The friction portion 320 is used to rub the sleeve 400 to melt the inner wall of the sleeve 400. The first threaded portion 310 is used to fit with the melted inner wall of the sleeve 400. The second threaded portion 330 is formed at one end of the bolt 300 close to the first nut 500 and is used to lock with the first nut 500. The friction portion 320 can make the bolt 300 generate sufficient friction with the sleeve 400 during the screwing process, which is conducive to the melting of the sleeve 400. The first threaded portion 310 fits with the melted sleeve 400 to form a tight and firm connection, so that the entire connection structure can withstand strong tension and shear force, thereby improving the stability of the connection between the lower shell 100 and the upper cover 200. The second threaded portion 330 is locked with the first nut 500, and the installation is simple and quick.

[0048] Preferably, if Figure 2 As shown, in this embodiment, a nut 340 is formed at one end of the bolt 300 away from the second thread. When the bolt 300 is rotated and pushed into the sleeve 400 and locked with the second nut 600, the nut 340 abuts against the lower shell 100 or the upper box cover 200.

[0049] like Figure 2As shown, in this embodiment, the first threaded portion 310 includes a first threaded segment 311 and a second threaded segment 312, and the first threaded segment 311 and the second threaded segment 312 have opposite threaded directions. Since the first threaded segment 311 and the second threaded segment 312 have opposite threaded directions, when the bolt 300 is engaged with the melted sleeve 400, they can respectively generate opposite torques with the inner wall of the cooled sleeve 400, which is conducive to further tightening the connection between the bolt 300 and the sleeve 400, thereby improving the stability of the connection.

[0050] like Figure 1 As shown, in this embodiment, the outer side wall of the other end of the sleeve 400 forms a limiting portion 410, and when the sleeve 400 passes through the first through hole and the second through hole, the limiting portion 410 abuts against the lower shell 100 or the upper case cover 200. The limiting portion 410 provides stable support and limiting for the sleeve 400, ensuring that the position of the sleeve 400 can be limited after passing through the first through hole and the second through hole, which is beneficial to prevent the sleeve 400 from being offset during subsequent assembly or use, and increases the installation accuracy of the sleeve 400.

[0051] It is worth mentioning that when the connection structure of the present embodiment is used to connect the lower housing 100 and the upper housing cover 200, the sleeve 400 may be passed through the first through hole and the second through hole in sequence, and after the position-limiting portion 410 abuts against the lower housing 100, the bolt 300 is rotated and pushed into the sleeve 400 from one side of the upper housing cover 200; or the sleeve 400 may be passed through the second through hole and the first through hole in sequence, and after the position-limiting portion 410 abuts against the upper housing cover 200, the bolt 300 is rotated and pushed into the sleeve 400 from one side of the lower housing 100. In the present embodiment, it is preferred that the sleeve 400 is connected by passing through the first through hole and the second through hole in sequence.

[0052] like Figure 1 As shown, in this embodiment, a heating ring 700 is further included, and the heating ring 700 is embedded in the inner side of the second nut 600, and the laser beam can heat the heating ring 700 through the melting hole 610, and further melt the limiting portion 410 through the heating ring 700. The laser beam heats the heating ring 700 to evenly transfer heat to the sleeve 400 through the heating ring 700, which is conducive to reducing the thermal stress concentration and deformation when the laser beam melts the sleeve 400, and improves the melting efficiency; and the heating ring 700 can also prevent the melted sleeve 400 from leaking and flowing out of the melting hole 610, thereby ensuring the integrity of the sleeve 400.

[0053] In this embodiment, the sleeve 400 is made of aluminum alloy; the heating ring 700 is made of one of tungsten, ceramic, and titanium alloy, so that the melting point of the heating ring 700 is higher than that of the sleeve 400. The melting point of the heating ring 700 is higher than that of the sleeve 400. During the laser beam heating process, the heating ring 700 can remain solid and will not melt or deform due to high temperature, ensuring that the heating ring 700 maintains stability and reliability during the melting of the sleeve 400, and preventing the melted sleeve 400 from being lost.

[0054] It is worth mentioning that the heating ring 700 is not limited to the use of the above-mentioned materials. It is only necessary to make the melting point of the heating ring 700 higher than that of the sleeve 400. When the laser beam is used to heat the heating ring 700, the sleeve 400 can be melted while the heating ring 700 remains solid, thereby preventing the melted sleeve 400 from flowing out of the melting hole 610 to maintain the integrity of the sleeve 400.

[0055] Preferably, in this embodiment, two melting holes 610 are formed on the second nut 600 .

[0056] In other embodiments, more than two melting holes 610 may be formed on the second nut 600 so as to selectively utilize one or more laser beams to melt the limiting portion 410 in a time-controlled manner.

[0057] like Figure 6 As shown, this embodiment also provides a connection method based on the above battery pack connection structure, comprising the following steps:

[0058] S1, fit the first through hole of the lower shell 100 and the second through hole of the upper cover 200, and pass the sleeve 400 embedded with the heating ring 700 through the first through hole and the second through hole, so that the limiting part 410 abuts against the lower shell 100 or the upper cover 200;

[0059] S2, preheating: applying torque and thrust to the bolt 300 synchronously, rotating and pushing the bolt 300 into the sleeve 400, and making the friction part 320 rub against the inner wall of the sleeve 400 to melt the inner wall of the sleeve 400 by frictional heat generation; at the same time, emitting a laser beam into the melting hole 610 to heat the heating ring 700 to make the limiting part 410 begin to melt;

[0060] S3, filling: reducing the power of the laser beam, increasing the torque and thrust of the bolt 300, so that the bolt 300 is pushed into the melted limiting portion 410, and the melted limiting portion 410 is squeezed and filled into the first through hole and / or the second through hole;

[0061] S4. Tightening: When the spacing between the second threaded portion 330 and the first nut 500 is 2 mm to 5 mm, the bolt 300 can continue to be pushed into the sleeve 400 while rapidly reducing the thrust applied to the bolt 300, and reducing the rotation speed of the bolt 300 and the power of the laser beam until the second threaded portion 330 and the first nut 500 are locked with each other.

[0062] By utilizing a combination of frictional heat generation and laser beam heating, the inner wall of the sleeve 400 and the limiting portion 410 are melted quickly, and when the bolt 300 is screwed and pushed into the sleeve 400, the melted sleeve 400 can be squeezed into the first through hole, the second through hole and the gap between the second nut 600 and the sleeve 400, thereby enhancing the strength and stability of the connection between the lower shell 100 and the upper box cover 200; at the same time, after the melted limiting portion 410 is filled into the first through hole and the second through hole and cooled, a tight sealing structure can be formed between the lower shell 100 and the upper box cover 200, which is beneficial to prevent leakage of liquid or gas inside the battery pack and improve the safety and reliability of the battery pack.

[0063] In this embodiment, in step S2, the rotation speed of the bolt 300 is 4500r / min to 9000r / min, the thrust on the bolt 300 is 1500N to 3500N, and the power of the laser beam is 2000W to 4800W. The rotation speed and thrust of the bolt 300 act together on the inner wall of the sleeve 400, and the sleeve 400 is quickly melted by frictional heat generation. Within the set rotation speed and thrust range, it can be ensured that the heat generated by friction is sufficient to melt the inner wall of the sleeve 400, while avoiding material splashing or deformation caused by overheating; within the power range of 2000W to 4800W, the laser beam can be efficiently transmitted to the heating ring 700 and the sleeve 400, so as to achieve rapid and uniform melting of the sleeve 400.

[0064] In this embodiment, in step S3, the rotation speed of the bolt 300 is 6000r / min to 10000r / min, which is greater than 20% of the rotation speed of the bolt 300 in step S2; the thrust force on the bolt 300 is 1800N to 5000N; the power of the laser beam is not less than 1600W, which is 10% to 20% lower than the power of the laser beam in step S2. Increasing the rotation speed of the bolt 300 can speed up the advancement speed of the bolt 300 in the sleeve 400, so that the melted limiter 410 can be more fully filled into the first through hole and the second through hole under the extrusion of the bolt 300, which is conducive to reducing the problem of insufficient filling or gaps caused by cooling and solidification of the sleeve 400, and ensuring the strength and reliability of the connection.

[0065] In this embodiment, in step S4, when the spacing between the second threaded portion 330 and the first nut 500 is 2 mm to 5 mm, the rotation speed of the bolt 300 is reduced to 60 r / min to 200 r / min, and the power of the laser beam is reduced to 600 W to 800 W, until the second threaded portion 330 is locked with the first nut 500. Reducing the rotation speed of the bolt 300 is conducive to reducing the vibration and impact force generated by high-speed rotation, making the engagement between the bolt 300 and the sleeve 400 more stable and tight, and helping to avoid loosening or damage of the thread due to vibration, thereby improving the quality of thread locking.

[0066] In other embodiments, in order to avoid chemical reaction between metal and gas in the air during the process of the bolt 300 rubbing the sleeve 400 and the laser beam heating the heating ring 700, an inert gas, such as nitrogen, argon, helium and other inert gases, can be filled into the connection between the lower shell 100 and the upper box cover 200 during the connection process. The inert gas can play a refining and protective role (the inert gas forms bubbles in the metal melt, and these bubbles will absorb the slag in the melt during the rising process and bring it out of the melt, thereby achieving a refining effect) to ensure the strength and stability of the connection between the lower shell 100 and the upper box cover 200.

[0067] Considering that the maintenance frequency of the battery pack is low, when the battery pack needs to be maintained, it is only necessary to use an external tool to forcibly unscrew the bolt 300, and then remove the sleeve 400 and the second nut 600 installed on the sleeve 400.

[0068] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A battery pack connection structure, used to fix a lower shell (100) and an upper box cover (200) of a battery pack to each other, characterized in that: include: A bolt (300), a sleeve (400), a first nut (500) and a second nut (600), wherein a first through hole is formed on the lower shell (100), and a second through hole is formed on the upper cover (200), one end of the bolt (300) passes through the first through hole and the second through hole, and is locked with the first nut (500); the sleeve (400) is sleeved on the bolt (300), and one end of the sleeve abuts against the first nut (500), and the sleeve (400) is configured to be melted so as to fit with the bolt (300); the second nut (600) is sleeved on the sleeve (400), and one end of the sleeve abuts against the first nut (500); A melting hole (610) is formed on the side wall of the second nut (600), and the melting hole (610) is used for the laser beam to enter so that the laser beam can melt the sleeve (400).

2. A battery pack connection structure according to claim 1, characterized in that: The bolt (300) is sequentially formed with a first threaded portion (310), a friction portion (320) and a second threaded portion (330); the friction portion (320) is used to rub the sleeve (400) to melt the inner wall of the sleeve (400); the first threaded portion (310) is used to fit with the melted inner wall of the sleeve (400); the second threaded portion (330) is formed at one end of the bolt (300) close to the first nut (500) and is used to be locked with the first nut (500).

3. A battery pack connection structure according to claim 2, characterized in that: The first threaded portion (310) comprises a first threaded segment (311) and a second threaded segment (312), and the threaded directions of the first threaded segment (311) and the second threaded segment (312) are opposite.

4. A battery pack connection structure according to claim 3, characterized in that: The outer wall of the other end of the sleeve (400) forms a limiting portion (410), and after the sleeve (400) passes through the first through hole and the second through hole, the limiting portion (410) abuts against the lower shell (100) or the upper box cover (200).

5. A battery pack connection structure according to claim 4, characterized in that: It also includes a heating ring (700), which is embedded in the inner side of the second nut (600), and the laser beam can heat the heating ring (700) through the melting hole (610), and further melt the limiting portion (410) through the heating ring (700).

6. A battery pack connection structure according to claim 5, characterized in that: The sleeve (400) is made of aluminum alloy; the heating ring (700) is made of one of tungsten, ceramic, and titanium alloy materials, so that the melting point of the heating ring (700) is higher than that of the sleeve (400).

7. A connection method based on the battery pack connection structure according to claim 6, characterized in that: The following steps are involved: S1, fitting the first through hole of the lower shell (100) and the second through hole of the upper box cover (200), and passing the sleeve (400) embedded with the heating ring (700) through the first through hole and the second through hole, so that the limiting portion (410) abuts against the lower shell (100) or the upper box cover (200); S2, preheating: applying torque and thrust to the bolt (300) synchronously, rotating and pushing the bolt (300) into the sleeve (400), and making the friction portion (320) rub against the inner wall of the sleeve (400) to melt the inner wall of the sleeve (400) by frictional heat generation; at the same time, emitting a laser beam into the melting hole (610) to heat the heating ring (700), further making the heating ring transfer heat to the limiting portion (410), so that the limiting portion (410) begins to melt; S3, filling: reducing the power of the laser beam, increasing the torque and thrust of the bolt (300), so that the bolt (300) moves to the melted limiting portion (410), and squeezes the melted limiting portion (410) to fill the first through hole and / or the second through hole; S4, tightening: when the spacing between the second threaded portion (330) and the first nut (500) is 2 mm to 5 mm, the thrust applied to the bolt (300) is rapidly reduced while the bolt (300) is allowed to continue to be pushed into the sleeve (400), and the rotation speed of the bolt (300) and the power of the laser beam are reduced until the second threaded portion (330) and the first nut (500) are locked with each other.

8. A battery pack connection method according to claim 7, characterized in that: In the step S2, the rotation speed of the bolt (300) is 4500 r / min to 9000 r / min, the thrust force applied to the bolt (300) is 1500 N to 3500 N, and the power of the laser beam is 2000 W to 4800 W.

9. A battery pack connection method according to claim 7, characterized in that: In step S3, the rotation speed of the bolt (300) is 6000 r / min to 10000 r / min, which is an increase of more than 20% compared with the rotation speed of the bolt (300) in step S2; the thrust force applied to the bolt (300) is 1800 N to 5000 N; and the power of the laser beam is not less than 1600 W, which is a decrease of 10% to 20% compared with the power of the laser beam in step S2.

10. A battery pack connection method according to claim 7, characterized in that: In the step S4, when the spacing between the second threaded portion (330) and the first nut (500) is 2 mm to 5 mm, the rotation speed of the bolt (300) is reduced to 60 r / min to 200 r / min, and the power of the laser beam is reduced to 600 W to 800 W until the second threaded portion (330) is locked with the first nut (500).

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