A middle rail synchronization structure for a slide rail

Abstract

This invention discloses a middle rail synchronization structure for a slide rail, belonging to the field of slide rail technology. The slide rail includes an outer rail, an inner rail, and a middle rail. The inner rail has a first retraction point and a first extension point relative to the middle rail, and the middle rail has a second retraction point and a second extension point relative to the outer rail. The middle rail synchronization structure further includes: a first spring piece, fixedly installed on the inner side of the middle rail, with its free end at least partially passing through a first slot on the middle rail and positioned on the outer side of the middle rail; the first spring piece also has at least one guide block; a second spring piece, fixedly installed on the inner rail and located in the gap between the inner rail and the middle rail; the second spring piece also has a slot corresponding to the guide block; and a limiting guide structure disposed on the outer rail. Through the locking and unlocking mechanism of the first and second spring pieces, automatic synchronization between the middle rail and the inner rail can be achieved during the slide rail pull-out process, with stable synchronization action.

Description

Technical Field

[0001] This invention relates to the field of slide rail technology, and in particular to a middle rail synchronization structure for a slide rail. Background Technology

[0002] In data center environments, servers are typically mounted on racks within server enclosures using sliding rails. With the continuous development of server technology and the increasing density of servers, the demands for server maintenance efficiency are also rising. Against this backdrop, three-section sliding rails, with their advantage of allowing for a larger travel distance, have gained widespread use in server racks.

[0003] In traditional three-section slide rail designs, to achieve synchronous extension of the middle and inner rails, ball joint mechanisms, slider control mechanisms, and gear transmission devices are commonly used. However, these traditional designs have several drawbacks. First, their structures are relatively complex, containing a large number of parts. This not only increases the difficulty and cost of the manufacturing process but also makes assembly cumbersome, requiring specialized tools and technicians. Second, due to the large number of parts, wear and loosening are prone to occur during long-term use, resulting in low durability and high maintenance difficulty and cost.

[0004] Therefore, the market needs a sliding rail center rail synchronization structure that is simple in structure, easy to install, and has stable synchronous operation. Summary of the Invention

[0005] This invention provides a middle rail synchronization structure for a slide rail to solve the problems in the prior art.

[0006] The present invention adopts the following technical solution: a middle rail synchronization structure for a slide rail, the slide rail including an outer rail, an inner rail, and a middle rail located between the outer rail and the inner rail, the middle rail being slidably connected to the outer rail, the inner rail being slidably connected to the middle rail, the inner rail having a first retraction point and a first extension point relative to the middle rail, and the middle rail having a second retraction point and a second extension point relative to the outer rail; characterized in that the middle rail synchronization structure further includes: a first spring piece, fixedly installed on the inner side of the middle rail, and the free end of the first spring piece at least partially passing through a first groove provided on the middle rail and placed on the outer side of the middle rail, the first spring piece also being provided with at least one guide block; a second spring piece, fixedly installed on the inner rail and located in the gap between the inner rail and the middle rail, the... The second spring is also provided with a slot corresponding to the guide block; and a limiting guide structure is provided on the outer rail; when the inner rail is at the first retraction point and the middle rail is at the second retraction point, the guide block is embedded in the slot to achieve relative locking of the first spring and the second spring, and the free end of the first spring elastically abuts against the inner side of the outer rail; the middle rail slides outward relative to the outer rail so that when the free end of the first spring is facing the limiting guide structure, it reaches the second extension point of the middle rail; as the middle rail continues to extend, the free end of the first spring moves away from the middle rail under the action of the limiting guide structure until the free end of the first spring elastically abuts against the outer side of the outer rail or the side of the limiting guide structure away from the middle rail, so that the guide block disengages from the slot.

[0007] Preferably, the inner rail has a stop at its front end; when the inner rail is at the first retraction point and the middle rail is at the second extension point, the stop abuts against the front end of the middle rail, and the guide block is directly opposite the slot; then the inner rail is pushed, and the stop moves the middle rail toward the second retraction point, and the free end of the first spring gradually detaches from the limiting guide structure and elastically resets toward the middle rail, so that the guide block is embedded in the slot.

[0008] Preferably, the free end of the first spring piece is configured as a recessed step structure; the limiting and guiding structure includes a limiting groove disposed on the outer rail and a guide block located in the limiting groove and connected to the outer rail, the guide block having a first plane and a first inclined surface on the side away from the middle rail, the first inclined surface connecting the first plane and the outer surface of the outer rail; when the middle rail is at the second extension point, the free end of the first spring piece is at least partially embedded in the limiting groove; as the middle rail continues to extend, the free end of the first spring piece moves at least partially along the first inclined surface to the outer surface of the outer rail, so that the guide block disengages from the slot.

[0009] Preferably, the free end of the first spring piece is also provided with a first arc-shaped surface; when the middle rail moves from the second extension point to the second retraction point, one side of the limiting groove contacts and squeezes the first arc-shaped surface, so that the free end of the first spring piece abuts against the inner side of the outer rail again.

[0010] Preferably, the guide block is provided with a first guide ramp; when the middle rail is at the second extension point and the inner rail moves from the first extension point to the first retraction point, the first guide ramp contacts and pushes the free end of the second spring piece to move elastically, so that the guide block is completely located between the first spring piece and the second spring piece, until the inner rail moves to the first retraction point, at which point the guide block is facing the slot.

[0011] Preferably, a first wall is provided on the inner rail, and the free end of the second spring sheet elastically abuts against the first wall in the direction close to the middle rail.

[0012] Preferably, two guide blocks are configured.

[0013] The above-described at least one technical solution adopted in the embodiments of the present invention can achieve the following beneficial effects: Firstly, this application primarily utilizes a first spring, a second spring, and a limiting guide structure to achieve synchronization between the middle rail and the inner rail. Compared to traditional ball-bearing linkage mechanisms, slider control mechanisms, and gear transmission devices, this method involves fewer parts and a simpler overall structure. Due to its simple structure and fewer required parts, the manufacturing and assembly processes are relatively easy, effectively reducing production costs. Furthermore, the simple structure makes installation more convenient and faster, requiring no complex operations or specialized tools, thus meeting the need for tool-free rapid installation and disassembly.

[0014] Secondly, the locking and unlocking mechanism of the first and second springs enables automatic synchronization between the middle and inner rails during the slide rail extension process. This stable synchronization reduces the occurrence of asynchronous extensions. The simplified structure reduces friction and interference between parts, lowers the probability of jamming, and ensures smooth slide rail deployment. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a three-dimensional structural diagram of the present invention when the inner rail is at the first retraction point and the middle rail is at the second retraction point. Figure 2 This is a front view of the present invention when the inner rail is at the first retraction point and the middle rail is at the second retraction point; Figure 3 for Figure 2 A three-dimensional structural sectional view of section AA in the middle; Figure 4 This is an exploded view of the slide rail of the present invention; Figure 5This is a front view of the present invention with the inner rail at the first retraction point and the middle rail at the second extension point; Figure 6 for Figure 5 A three-dimensional structural sectional view of section BB in the middle section; Figure 7 This is a front view of the first spring piece of the present invention with its free end abutting against the outer side of the outer rail; Figure 8 for Figure 7 A three-dimensional structural sectional view of the CC section; Figure 9 For the explosion of the first and second fragments of the present invention Figure 1 ; Figure 10 For the explosion of the first and second fragments of the present invention Figure 2 .

[0016] Figure Labels 1-Outer rail; 11-Limiting and guiding structure; 12-Limiting groove; 13-Guide block; 131-First plane; 132-First inclined plane; 2-Inner rail; 21-Blocking point; 22-First wall; 3-Middle rail; 31-First slot; 4-First spring clip; 41-Guide block; 411-First guide ramp; 42-First arc-shaped surface; 43-First part; 44-Second part; 45-Third part; 46-First rounded corner; 47-Second rounded corner; 5-Second spring sheet; 51-Card slot; 52-Main sheet structure; 53-Pressure plate; 54-Third rounded corner. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] In server rooms, servers are mounted on racks using sliding rails. With increasing demands for server density and maintenance efficiency, three-section sliding rails have become widely used in server racks. As an existing technology, three-section sliding rails consist of an inner rail, a middle rail, and an outer rail. The inner rail and middle rail are slidably connected, as are the middle rail and outer rail. In this type of rail, the inner rail 2, middle rail 3, and outer rail 1 must achieve stable and smooth extension and retraction. In existing technologies, common methods to achieve synchronized extension of the middle rail 3 and inner rail 2 include ball joint mechanisms, slider control mechanisms, and gear transmission devices. While these designs can partially achieve synchronization, they are structurally complex, have high manufacturing and assembly costs, numerous parts, low durability, and inconvenient maintenance. Furthermore, asynchronous extension or jamming is prone to occur during repeated use.

[0020] Reference Figures 1 to 9 As shown, an embodiment of the present invention provides a middle rail synchronization structure for a slide rail. The slide rail includes an outer rail 1, an inner rail 2, and a middle rail 3 located between the outer rail 1 and the inner rail 2. The middle rail 3 is slidably connected to the outer rail 1, and the inner rail 2 is slidably connected to the middle rail 3. The inner rail 2 has a first retraction point and a first extension point relative to the middle rail 3, and the middle rail 3 has a second retraction point and a second extension point relative to the outer rail 1. The middle rail synchronization structure further includes a first spring 4, a second spring 5, and a limiting and guiding structure 11 disposed on the outer rail 1.

[0021] The first spring plate 4 is fixedly installed on the inner side of the middle rail 3, and the free end of the first spring plate 4 passes through at least part of the first slot 31 provided on the middle rail 3 and is placed on the outer side of the middle rail 3. The first spring plate 4 is also provided with at least one guide block 41; the second spring plate 5 is fixedly installed on the inner rail 2 and is located in the gap between the inner rail 2 and the middle rail 3. The second spring plate 5 is also provided with a slot 51 corresponding to the guide block 41; when the inner rail 2 is at the first retraction point and the middle rail 3 is at the second retraction point (e.g. Figures 1 to 4 The guide block 41 is embedded in the slot 51 to achieve relative locking of the first spring 4 and the second spring 5, and the free end of the first spring 4 elastically abuts against the inner side of the outer rail 1; the middle rail 3 slides outward relative to the outer rail 1 so that when the free end of the first spring 4 is directly facing the limiting guide structure 11, it reaches the second extension point of the middle rail 3 (e.g., Figure 6 ); as the middle rail 3 continues to extend (such as Figure 8 The free end of the first spring piece 4 moves away from the middle rail 3 under the action of the limiting guide structure 11 until the free end of the first spring piece 4 elastically abuts against the outer side of the outer rail 1 or the side of the limiting guide structure 11 away from the middle rail 3, so that the guide block 41 disengages from the slot 51.

[0022] When the inner rail 2 is at the first retraction point and the middle rail 3 is at the second retraction point, the guide block 41 on the first spring 4 engages with the slot 51 of the second spring 5, achieving relative locking between the first spring 4 and the second spring 5. Simultaneously, the free end of the first spring 4 elastically abuts against the inner side of the outer rail 1 (at this time, the elastic force of the first spring 4 points away from the middle rail 3). At this point, the inner rail 2 and the middle rail 3 are in a locked synchronized state. At this time, the server is in a state of complete retraction within the cabinet.

[0023] When the server is pulled outward, since the server is fixed on the inner rail 2, the inner rail 2 will move with the server. Due to the locking of the first spring 4 and the second spring 5, the inner rail 2 will drive the middle rail 3 to slide outward relative to the outer rail 1, achieving synchronous extension of the inner rail 2 and the middle rail 3. When the middle rail 3 slides outward relative to the outer rail 1, so that the free end of the first spring 4 is directly facing the limiting guide structure 11, the middle rail 3 reaches the second extension point. As the middle rail 3 continues to extend, the free end of the first spring 4 moves away from the middle rail 3 under the action of the limiting guide structure 11, until the free end of the first spring 4 elastically abuts against the outside of the outer rail 1 or the side of the limiting guide structure 11 away from the middle rail 3 (at this time, the elastic force of the first spring 4 points towards the middle rail 3). At this time, the guide block 41 can be disengaged from the slot 51, the locking between the inner rail 2 and the middle rail 3 is released, and the inner rail 2 can slide out or slide back independently. It should be noted that there are generally two guide blocks 41, which can increase the stability of locking. Similarly, there are also two corresponding slots 51, each corresponding to one of the two guide blocks 41.

[0024] In summary, this application primarily utilizes the first spring 4, the second spring 5, and the limiting guide structure 11 to achieve synchronization between the middle rail 3 and the inner rail 2. Compared to traditional ball-bearing linkage mechanisms, slider control mechanisms, and gear transmission devices, this method involves fewer parts and a simpler overall structure. Due to its simple structure and fewer required parts, the manufacturing and assembly processes are relatively easy, effectively reducing production costs. Furthermore, the simple structure makes installation more convenient and faster, requiring no complex operations or specialized tools, thus meeting the need for tool-free rapid installation and disassembly.

[0025] Furthermore, the locking and unlocking mechanism of the first spring 4 and the second spring 5 enables automatic synchronization between the middle rail 3 and the inner rail 2 during the slide rail extension process. This stable synchronization reduces the occurrence of asynchronous extensions. The simple structure reduces friction and interference between parts, lowers the probability of jamming, and ensures smooth slide rail deployment.

[0026] In some practical applications, refer to Figure 1As shown, the inner rail 2 has a stop point 21 at its front end; when the inner rail 2 is at the first retraction point and the middle rail 3 is at the second extension point, the stop point 21 abuts against the front end of the middle rail 3, and the guide block 41 is directly opposite the slot 51; then the inner rail 2 is pushed, and the stop point 21 drives the middle rail 3 to move towards the second retraction point, and the free end of the first spring piece 4 gradually disengages from the limiting guide structure 11 and elastically resets towards the middle rail 3, so that the guide block 41 is embedded in the slot 51.

[0027] Pulling the inner rail 2 outward causes the first spring piece 4 and the second spring piece 5 to lock together, causing the inner rail 2 to slide outward relative to the outer rail 1, achieving synchronous extension. The outward sliding of the middle rail 3 brings the free end of the first spring piece 4 directly opposite the limiting guide structure 11, reaching the second extension point. Continuing to extend the middle rail 3, the free end of the first spring piece 4 moves away from the middle rail 3 under the action of the limiting guide structure 11, the guide block 41 disengages from the slot 51, the locking between the inner rail 2 and the middle rail 3 is released, and the inner rail 2 can move independently.

[0028] When the inner rail 2 is retracted, it slides relative to the middle rail 3, so that the inner rail 2 is at the first retraction point and the middle rail 3 is at the second extension point. At this time, the stop 21 at the front end of the inner rail 2 abuts against the front end of the middle rail 3, and the guide block 41 is aligned with the slot 51. When the inner rail 2 is pushed, the stop 21 moves the middle rail 3 toward the second retraction point. The free end of the first spring piece 4 gradually disengages from the limiting guide structure 11 and elastically resets toward the middle rail 3. The guide block 41 then re-enters the slot 51, and the inner rail 2 and the middle rail 3 return to the locked synchronous state, retracting inward together, while also preparing for the next synchronous extension of the inner rail 2 and the middle rail 3.

[0029] In this embodiment, the inner rail 2 and the middle rail 3 can move synchronously during both the extension and retraction of the server, making user operation more convenient. During retraction, the setting of the stop point 21 naturally enables the inner rail 2 to retract along with the middle rail 3, eliminating the need for additional complex operations to realign and lock the inner rail 2 and the middle rail 3.

[0030] In some practical applications, based on any of the above implementation methods: Refer to Figure 3 , Figure 4 , Figure 6 and Figure 8As shown, the free end of the first spring piece 4 is configured as a recessed step structure; the limiting guide structure 11 includes a limiting groove 12 disposed on the outer rail 1, and a guide block 13 located in the limiting groove 12 and connected to the outer rail 1. The guide block 13 has a first plane 131 and a first inclined surface 132 on the side away from the middle rail 3. The first inclined surface 132 connects the first plane 131 and the outer surface of the outer rail 1. When the middle rail 3 is at the second extension point, the free end of the first spring piece 4 is at least partially embedded in the limiting groove 12. As the middle rail 3 continues to extend, the free end of the first spring piece 4 moves at least partially along the first inclined surface 132 to the outer surface of the outer rail 1, so that the guide block 41 disengages from the slot 51.

[0031] When the inner rail 2 is at the first retraction point and the middle rail 3 is at the second retraction point, the guide block 41 on the first spring 4 is embedded in the slot 51 of the second spring 5, and the free end of the first spring 4 (i.e., the recessed step structure) elastically abuts against the inner side of the outer rail 1, locking the inner rail 2 and the middle rail 3 synchronously. During the outward sliding of the middle rail 3, when it reaches the second extension point, the free end (recessed step structure) of the first spring 4 is at least partially embedded in the limiting groove 12 on the outer rail 1. At this time, the guide block 41 is still in the slot 51, and the inner rail 2 and the middle rail 3 remain relatively locked.

[0032] As the middle rail 3 continues to extend, the recessed step structure of the free end of the first spring piece 4 moves at least partially along the first inclined surface 132 of the guide block 13. Because the first inclined surface 132 connects the first plane 131 and the outer side of the outer rail 1, the free end of the first spring piece 4 will gradually move away from the middle rail 3 until it reaches the outer side of the outer rail 1, so that the free end of the first spring piece 4 elastically abuts against the outer side of the outer rail 1 in a direction closer to the middle rail 3. During this process, the guide block 41 disengages from the slot 51, the lock between the inner rail 2 and the middle rail 3 is released, and the inner rail 2 can slide out or slide back relative to the middle rail 3 independently.

[0033] When the inner rail 2 retracts, as it returns to the first retraction point and the middle rail 3 is at the second extension point, the stop point 21 at the front end of the inner rail 2 abuts against the front end of the middle rail 3, and the guide block 41 faces the slot 51. Pushing the inner rail 2 causes the stop point 21 to move the middle rail 3 toward the second retraction point. During this movement, the free end of the first spring piece 4 elastically resets itself along the first inclined surface 132 and the first plane 131 toward the middle rail 3 under the action of elastic force. The guide block 41 re-embeds into the slot 51, and the inner rail 2 and the middle rail 3 return to their locked synchronous state, retracting inward together.

[0034] In this embodiment, the recessed step structure at the free end of the first spring piece 4 cooperates with the first inclined surface 132 in the limiting guide structure 11, making the unlocking process smoother. The inclined surface design provides a gradual guide for the movement of the free end of the first spring piece 4, reducing the possibility of jamming and wear, and further improving the smoothness and durability of the slide rail.

[0035] The limiting groove 12 provides accurate positioning for the free end of the first spring piece 4, ensuring that when the middle rail 3 reaches the second extension point, the first spring piece 4 can accurately engage with the first plane 131 and the first inclined plane 132 in the limiting guide structure 11. This helps improve the accuracy and stability of the unlocking action, ensuring that the inner rail 2 and the middle rail 3 can reliably achieve synchronization and separation.

[0036] Furthermore, the design of the sunken step structure and the limiting guide structure 11 allows for complex functions to be achieved within a limited space, making the entire slide rail structure more compact. This is highly advantageous for applications with high space requirements, such as server racks.

[0037] Specifically, the free end of the first spring piece 4 is also provided with a first arc-shaped surface 42; when the middle rail 3 moves from the second extension point to the second retraction point, one side of the limiting groove 12 contacts and presses the first arc-shaped surface 42, so that the free end of the first spring piece 4 abuts against the inner side of the outer rail 1 again. This design facilitates the free end of the first spring piece 4 (i.e., the recessed step structure) to smoothly disengage from the limiting groove 12 and abut against the inner side of the outer rail 1 again.

[0038] In some practical applications, refer to Figure 9 As shown, the guide block 41 is provided with a first guide ramp 411. When the middle rail 3 is at the second extension point and the inner rail 2 moves from the first extension point to the first retraction point, the first guide ramp 411 contacts and pushes the free end of the second spring 5 to move elastically, so that the guide block 41 is completely located between the first spring 4 and the second spring 5, until the inner rail 2 moves to the first retraction point, at which point the guide block 41 is directly facing the slot 51. Since the server slide rail has strict volume requirements, the design space must be minimized as much as possible. Therefore, by setting the first guide ramp, when the first spring and the second spring contact, the first guide ramp can squeeze the free end of the second spring to achieve a mutual locking effect, so as to utilize the minimum space between the inner rail and the middle rail to achieve synchronous movement of the inner rail and the middle rail. Relatively speaking, this is also the most cost-effective method.

[0039] In some practical applications, the inner rail 2 is provided with a first wall 22 (e.g. Figure 3The free end of the second spring piece 5 elastically abuts against the first wall 22 in the direction closer to the middle rail 3. The first wall 22 on the inner rail is designed to limit the free end of the second spring piece when it elastically deforms towards the middle rail in advance, so as to prevent friction between the free end of the second spring piece and the middle rail element.

[0040] In summary, in some practical applications, refer to Figure 10 As shown, the first spring piece 4 includes a first part 43 and a second part 44 distributed in staggered layers. The first part and the second part are connected by a third part 45. The connection between the first part and the third part is configured with a first rounded corner 46, and the connection between the second part and the third part is configured with a second rounded corner 47. The end of the first part away from the third part is fixed on the outer rail. The guide block 41 is installed on the first part.

[0041] The back side of the second rounded corner 47 is the first arc-shaped surface 42; at least part of the structure of the second part, the third part, and the first part is the sunken step structure described above. At the same time, when the third part is inside the limiting groove 12, the guide block 13 blocks the third part, which can prevent the middle rail from continuing to extend forward relative to the outer rail when the inner rail continues to extend, thus limiting the middle rail.

[0042] In some practical applications, the second spring includes a main sheet structure 52 and a pressure plate 53 formed by bending the end of the main sheet structure upward; the connection between the pressure plate and the main sheet structure is configured with a third rounded corner 54.

[0043] The part where the second spring 5 contacts the first wall 22 is the pressure plate; the drop between the third rounded corner and the pressure plate should be increased according to the actual situation (not specifically shown in the figure), so that the guide block on the first spring can extend more into the corresponding slot, increasing the locking stability between the two.

[0044] To minimize the overall size of the slide rail, the gap between the inner rail 2 and the middle rail 3 should be minimized. This results in the first and second spring pieces mutually restricting or blocking each other during relative sliding between the inner and middle rails. Therefore, by setting a first rounded corner and a third rounded corner, such as... Figure 3As shown, when the second spring piece moves closer to the first spring piece from the left, even if the gap between the inner rail and the middle rail decreases, only the first rounded corner and the third rounded corner will contact each other. Under the action of the first and third rounded corners, the first and second spring pieces can overcome the elastic deformation respectively, allowing them to continue to move relative to each other. Ultimately, the guide block is embedded in the slot, achieving the synchronous retraction of the inner rail and the middle rail again. It should be noted that the smoothness of the relative sliding between the inner rail and the middle rail can be ensured by further increasing the radius of the first rounded corner and / or the third rounded corner. Under certain circumstances, the change in the radius of the two rounded corners can further reduce the gap between the inner rail and the middle rail, making the entire slide rail structure more compact.

[0045] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A middle rail synchronization structure of a slide rail, the slide rail comprising an outer rail, an inner rail and a middle rail located between the outer rail and the inner rail, the inner rail having a first retraction point and a first extension point relative to the middle rail, the middle rail having a second retraction point and a second extension point relative to the outer rail; characterized in that, The intermediate-track synchronization structure also includes: The first spring is installed inside the middle rail, and the free end of the first spring passes through at least part of the first slot provided on the middle rail and is placed outside the middle rail. The first spring is also provided with a guide block. The second spring is installed on the inner rail and located in the gap between the inner rail and the middle rail. The second spring is also provided with a slot corresponding to the guide block; and a limiting guide structure is provided on the outer rail. When the inner rail is at the first retraction point and the middle rail is at the second retraction point, the guide block is embedded in the slot to achieve relative locking of the first and second spring pieces, and the free end of the first spring piece elastically abuts against the inner side of the outer rail; the middle rail slides outward relative to the outer rail so that when the free end of the first spring piece is facing the limiting guide structure, the second extension point of the middle rail is reached; as the middle rail continues to extend, the free end of the first spring piece moves away from the middle rail under the action of the limiting guide structure until the free end of the first spring piece elastically abuts against the outer side of the outer rail or the side of the limiting guide structure away from the middle rail, so that the guide block disengages from the slot; The inner rail is provided with a stop at its front end; when the inner rail is at the first retraction point and the middle rail is at the second extension point, the stop abuts against the front end of the middle rail, and the guide block is directly opposite the slot; then the inner rail is pushed, and the stop moves the middle rail toward the second retraction point, and the free end of the first spring gradually detaches from the limiting guide structure and elastically resets toward the middle rail, so that the guide block is embedded in the slot; The free end of the first spring is configured as a recessed step structure; the limiting guide structure includes a limiting groove disposed on the outer rail and a guide block located in the limiting groove and connected to the outer rail. The guide block has a first plane and a first inclined surface on the side away from the middle rail. The first inclined surface connects the first plane and the outer surface of the outer rail. When the middle rail is at the second extension point, the free end of the first spring piece is at least partially embedded in the limiting groove; as the middle rail continues to extend, the free end of the first spring piece moves at least partially along the first inclined surface to the outer side of the outer rail, so that the guide block disengages from the slot. The first spring includes a first part and a second part that are staggered and connected by a third part; the end of the first part away from the third part is fixed to the outer rail; the guide block is mounted on the first part.

2. The middle rail synchronization structure of a slide rail according to claim 1, characterized in that, The free end of the first spring piece is also provided with a first arc-shaped surface; when the middle rail moves from the second extension point to the second retraction point, one side of the limiting groove contacts and squeezes the first arc-shaped surface, so that the free end of the first spring piece abuts against the inner side of the outer rail again.

3. The middle rail synchronization structure of a slide rail according to claim 1, characterized in that, The guide block is provided with a first guide slope; when the middle rail is at the second extension point and the inner rail moves from the first extension point to the first retraction point, the first guide slope contacts and pushes the free end of the second spring piece to move elastically, so that the guide block is completely located between the first spring piece and the second spring piece, until the inner rail moves to the first retraction point, at which point the guide block is facing the slot.

4. The middle rail synchronization structure of a slide rail according to claim 1, characterized in that, The inner rail is provided with a first wall, and the free end of the second spring piece elastically abuts against the first wall in the direction closer to the middle rail.

5. The middle rail synchronization structure of a slide rail according to claim 1, characterized in that, There are two guide blocks.

6. The middle rail synchronization structure of a slide rail according to claim 1, characterized in that, The connection between the first part and the third part is configured with a first rounded corner, and the connection between the second part and the third part is configured with a second rounded corner.

7. A middle rail synchronization structure for a slide rail according to claim 4 or 6, characterized in that, The second spring includes a main sheet structure and a pressure plate formed by bending the end of the main sheet structure upward; the connection between the pressure plate and the main sheet structure is configured with a third rounded corner.

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