A telescopic sleeve length adjustment device

Abstract

This utility model relates to the field of telescopic sleeves, specifically to a telescopic sleeve length adjustment device. It includes a telescopic sleeve assembly consisting of an outer tube and at least one inner tube. The innermost inner tube has no limiting hole, while at least the second innermost inner tube of the outer sleeve has at least one limiting hole. A control area is provided at the bottom of the inner tube closest to the limiting hole, nested within the sleeve with the limiting hole. A limiting component and a reversing component are provided within this area. The limiting component includes a limiting tongue, a limiting shaft, and a limiting torsion spring, causing the limiting tongue to tend to extend outwards and engage with the limiting hole. The reversing component includes a reversing spring, a reversing shaft, and a reversing torsion spring. The first end of the reversing spring acts on the tail of the limiting tongue to maintain or release the retracted state of the limiting tongue. This device achieves automated telescopic extension and retraction of multiple sleeve sections, solving the problems of low efficiency and inconvenience in existing multi-section telescopic sleeves that require individual operation of each section.

Description

Technical Field

[0001] This utility model relates to the field of telescopic sleeves, specifically to a telescopic sleeve length adjustment device. Background Technology

[0002] In the current field of furniture and mechanical equipment support and adjustment, telescopic sleeve structures are widely used due to their reliable mechanical performance and cost controllability. However, existing technologies suffer from a long-standing core deficiency: the lack of a systematic solution that can automate the sequential extension and retraction of multiple sleeve sections through simple mechanical linkage. Specifically, traditional screw-type adjustment relies on specialized tools, which is cumbersome and poses safety hazards due to exposed holes; while ball-operated structures can achieve tool-free operation, their design inherently limits their application to two-section extension scenarios, severely restricting the adjustment range; hand-cranked screw devices suffer from high failure rates and maintenance costs due to complex transmission components; and pneumatic or hydraulic solutions have inherent problems such as the risk of media leakage and poor environmental adaptability. Particularly noteworthy is that when users need to adjust the length of three or more telescopic sleeve sections, existing technologies require users to perform independent pull-out, positioning, locking, and unlocking operations for each section. The entire process is cumbersome, inefficient, and provides a fragmented user experience, failing to meet the growing demands of modern furniture and equipment for convenience and intelligent operation. Summary of the Invention

[0003] The purpose of this utility model is to provide a telescopic sleeve length adjustment device to solve the problems of low efficiency and inconvenience in the prior art, which requires telescopic sleeves to be operated section by section individually.

[0004] To achieve the above objectives, the following technical solution is adopted.

[0005] A telescopic sleeve length adjustment device includes a telescopic sleeve assembly, the telescopic sleeve assembly including an outer tube as an outer sleeve and at least one inner tube nested inside the outer tube; The innermost inner tube has no limiting hole, the next innermost inner tube has at least one limiting hole, and other outer tubes may be equipped with limiting holes (0, 1 or more). All limiting holes are arranged along the axial direction of the tube and are used to allow the limiting tongue to extend for length positioning. A control area is provided at the bottom of the inner tube closest to the limiting hole, nested inside the tube with the limiting hole. The control area is provided with a limiting component and a reversing component. The limiting assembly includes a limiting tongue, a limiting shaft, and a limiting torsion spring. The limiting tongue and the limiting torsion spring are hinged to the lower part of the inner tube through the limiting shaft. The limiting torsion spring acts on the limiting tongue to make the head of the limiting tongue tend to extend outward from the limiting hole. The reversing assembly includes a reversing spring, a reversing shaft, and a reversing torsion spring. The reversing spring and the reversing torsion spring are hinged to the control area via the reversing shaft. The first end of the reversing spring acts on the tail of the limiting tongue to selectively maintain or release the retracted state of the limiting tongue.

[0006] Optionally, it also includes a middle sleeve and a positioning sleeve. The middle sleeve covers the top inner and outer walls of the outer sleeve except for the innermost inner tube, and the positioning sleeve covers the bottom of the outer wall of the inner tube except for the outer tube. The middle sleeve and the positioning sleeve are clamped together between adjacent inner and outer sleeves to maintain the axial alignment of the sleeves and limit the maximum extension length.

[0007] Optionally, the inner wall of the middle sleeve of the sleeve with the limiting hole is provided with a reversing point. The reversing point is used to squeeze the head of the limiting tongue to rotate inward to a retracted state when the limiting tongue moves upward past its position. The tail of the limiting tongue is provided with a reversing groove; the first end of the reversing spring clip maintains the retracted state of the limiting tongue by engaging with the reversing groove.

[0008] Optionally, the head of the limiting tongue is a wedge-shaped structure, with its outer surface being an arc-shaped transition surface for smooth sliding along the inner wall of the sleeve, and its inner surface being used to be stuck by the edge of the limiting hole.

[0009] Optionally, the inner tube with the control area has an opening at the bottom, and the outer sleeve has a closed tube bottom. The second end of the reversing spring extends downward out of the opening and is squeezed by the tube bottom when the inner tube moves to the bottom of the outer sleeve, thereby releasing the first end of the reversing spring from the retracted state of the limiting tongue.

[0010] Optionally, the inner tube has at least two layers; the telescopic sequence adjustment assembly includes an extension sequence spring pin, a sequence limiting hole, and a retraction sequence spring pin; wherein, the extension sequence spring pin is only located at the bottom of the innermost inner tube; the sequence limiting hole is located at the bottom of all inner tubes; the retraction sequence spring pin is located at the top of the outer sleeves other than the innermost and second innermost inner tubes, and extends into the tube through the sleeve wall.

[0011] Optionally, the top of the innermost sleeve is provided with a connector for connecting furniture legs or mechanical support components.

[0012] Optionally, the telescopic sleeve is a tubular structure or a non-completely enclosed groove structure.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The telescopic sleeve length adjustment device provided by this utility model, by nesting inside a sleeve with limiting holes, has an integrated control area located at the bottom of the inner tube closest to it. Within this area, limiting components and reversing components work in concert, forming the core foundation for automated adjustment. The limiting component, through the action of a torsion spring, always tends to extend outwards, allowing it to automatically engage with the limiting hole of the outer sleeve when the sleeve extends, achieving rapid and reliable step-by-step positioning. The reversing component, through the interaction between a reversing spring and the tail of the limiting tongue, dynamically maintains or releases the retracted state of the limiting tongue according to the sleeve's position, thus achieving intelligent switching of the telescopic function. This basic mechanical structure not only fundamentally changes the way sleeve extension and retraction can be completed with a single lifting or pressing action, completely eliminating the cumbersome process of operating each section of traditional multi-section sleeves, but its modular design also provides a robust and flexible structural platform for multi-section expansion of the system.

[0014] Building upon this foundation, and addressing the complex applications of three-section and multi-section sleeves, a telescopic sequence adjustment assembly consisting of an extension sequence spring pin, a sequence limiting hole, and a retraction sequence spring pin is added. This precisely sets the action sequence of each sleeve layer, ensuring sequential and automated linkage from the outer layer to the inner layer during extension and from the inner layer to the outer layer during retraction. The cooperation between the middle sleeve and the positioning sleeve structurally guarantees the axial alignment and smooth movement of each sleeve layer during relative sliding. The trigger mechanism, consisting of the reversing point on the inner wall of the middle sleeve and the reversing groove at the end of the limiting tongue, enables automatic and reliable switching and resetting of the limit function at specific positions. This series of progressively advanced technical solutions, from basic locking and reversing to motion guidance and stroke limitation, and then to complex sequence control, together constitute a complete, rigorous, and efficient fully automatic sequence control logic. Ultimately, this device makes the length adjustment process of multi-section telescopic sleeves simpler, smoother, and more reliable than ever before, greatly improving the user experience. At the same time, its purely mechanical solution also has significant advantages such as durable structure, controllable cost, and convenient maintenance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a telescopic sleeve length adjustment device according to the present invention; Figure 2 This is a schematic diagram illustrating the failure of the reversing component and the limiting component of the telescopic sleeve length adjustment device of this utility model. Figure 3 This is a schematic diagram illustrating the operation of the reversing component and the limiting component function restoration of the telescopic sleeve length adjustment device of this utility model. Figure 4 This is a schematic diagram of the structure of a three-section telescopic sleeve length adjustment device according to the present invention; Figure 5 This is a schematic diagram illustrating the operation of a furniture height adjustment device based on a telescopic sleeve length adjustment device of this utility model. Figure 6 This is a schematic diagram illustrating the operation of a sunshade angle adjustment device, which is a telescopic sleeve length adjustment device according to this utility model.

[0016] The components include: 1. Outer tube; 12. Limiting hole; 2. Inner tube; 21. First inner tube; 22. Second inner tube; 3. Tube sleeve; 31. Middle layer sleeve; 311. First middle layer sleeve; 312. Second middle layer sleeve; 32. Positioning sleeve; 321. First positioning sleeve; 322. Second positioning sleeve; 4. Limiting assembly; 41. Limiting tongue; 42. Limiting shaft; 43. Limiting torsion spring; 5. Reversing assembly; 51. Reversing spring; 52. Reversing shaft; 53. Reversing torsion spring; 54. Reversing point; 55. Reversing slot; 6. Extension sequence adjustment assembly; 61. Extension sequence spring pin; 62. Sequence limiting hole; 63. Retraction sequence spring pin; 7. Sunshade. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0018] The following detailed description is exemplary and intended to provide further detailed explanation of the present invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to the present invention.

[0019] like Figures 1-6 As shown, this utility model provides a telescopic sleeve length adjustment device. The outermost layer of the sleeve assembly is an outer tube 1, and at least one inner tube 2 is nested inside it. For ease of description, the following will take a three-layer structure including an outer tube 1, a first inner tube 21, and a second inner tube 22 as an example for detailed explanation. However, it should be understood that by increasing the number of inner tubes 2, it can be expanded to more layers, and the basic principle remains the same.

[0020] The outer tube 1 serves as the outermost supporting structure, with its bottom closed to form the outer tube bottom. There is also an inner tube bottom at the bottom of the sleeve with the limiting hole. Within the sleeve with the limiting hole, in the bottom region of the closest nested inner tube 2, a dedicated control area is provided. This control area is an integrated functional unit, housing the core mechanical components that realize the sleeve's extension, retraction, and locking functions—the limiting component 4 and the reversing component 5.

[0021] Based on the required adjustment range and precision, it is determined whether or not a limiting hole 12 is provided along the axial direction of each layer of the telescopic sleeve assembly, and one or more limiting holes 12 are provided. In practice, depending on the required range of telescopic adjustment and the precision requirements of the telescopic sleeve, some sleeves do not need to have limiting holes 12, while others only need to have one or more limiting holes 12. For example, in a portable telescopic basketball hoop composed of four telescopic sleeves, since the height of the basketball hoop is fixed and uniform, only one limiting hole 12 and a closed tube bottom are needed on the upper part of the innermost inner tube, and only a set of limiting components 4 and reversing components 5 are needed on the bottom of the innermost inner tube to meet the height adjustment requirements of the basketball hoop. For example, a three-section height-adjustable desk and chair for primary and secondary school students during lunch break requires multiple equidistant limiting holes 12 on the outer tube 1 to meet the needs of students of different heights for adjusting the desktop height when sitting. The first inner tube 21 only needs to have one limiting hole 12 at the top to meet the needs of students to raise the desktop when lying down. In conjunction with the use of the limiting hole 12, control areas need to be set on both the first inner tube 21 and the second inner tube 22. Each control area has a set of limiting components 4 and reversing components 5.

[0022] The limiting assembly 4 consists of three main parts: a limiting tongue 41, a limiting shaft 42, and a limiting torsion spring 43. The limiting tongue 41 is hinged to the control area at the bottom of the inner tube 2 via the limiting shaft 42, allowing the limiting tongue 41 to rotate within a certain angle around the limiting shaft 42. The limiting torsion spring 43 acts on the limiting tongue 41, providing it with a continuous torque that causes the head of the limiting tongue 41 to extend outward from the sleeve wall. Therefore, in its natural state, the head of the limiting tongue 41 always has a tendency to pop out under the action of the limiting torsion spring 43. When the inner tube 2 slides inside the outer sleeve and the head of the limiting tongue 41 aligns with the limiting hole 12 on the outer sleeve wall, the limiting tongue 41 will quickly pop out and engage with the limiting hole 12, thereby preventing the inner tube 2 from moving downward and achieving reliable locking of this position.

[0023] Working in conjunction with the limiting assembly 4 is the reversing assembly 5. The reversing assembly 5 includes a reversing spring 51, a reversing shaft 52, a reversing torsion spring 53, a reversing point 54, and a reversing slot 55. The reversing spring 51 is hinged within the control area via the reversing shaft 52, and under the action of the reversing torsion spring 53, its first end is always in contact with the tail of the limiting tongue 41 or in a ready-to-access position. The second end of the reversing spring 51 is designed to slope downwards and protrude from the bottom opening of the corresponding inner tube 2 control area. The tail of the limiting tongue 41 is provided with a reversing slot 55, which is used to engage with the first end of the reversing spring 51.

[0024] The reversing point 54 is located on the inner wall of the middle sleeve 31. The reversing point 54 is an inwardly protruding structure. Its function is that when a certain inner tube 2 is pulled upward, the head of its limiting tongue 41 slides past the inner wall of the outer sleeve and finally passes the reversing point 54 of the top of the middle sleeve 31 of the outer sleeve. The reversing point 54 will squeeze the head of the limiting tongue 41, forcing the limiting tongue 41 to rotate inward against the force of its limiting torsion spring 43, causing its head to retract. At this time, if the reversing groove 55 at the tail of the limiting tongue 41 rotates to the position corresponding to the first end of the reversing spring 51, the first end of the reversing spring 51 will quickly engage in the reversing groove 55 under the action of its own reversing torsion spring 53. This engaged state can overcome the elastic force of the limiting torsion spring 43 and stably keep the limiting tongue 41 in the retracted position, thereby temporarily releasing the limiting function of the limiting component 4, so that the inner tube 2 can slide freely up and down in its outer sleeve without being stuck by the limiting hole 12.

[0025] The inner tube 2 has an opening in its bottom control area, through which the second end of the reversing spring 51 extends downwards at an angle. This design aims to achieve automatic reset of the reversing assembly 5. When the inner tube 2 (with the limit function released) moves downwards until its bottom touches the bottom of the inner tube of the outer sleeve (or the bottom of the second innermost inner tube for the innermost inner tube) or the bottom of the outer tube (for the first inner tube 21), the protruding second end of the reversing spring 51 contacts the bottom of the outer sleeve before the bottom of the inner tube. This contact action applies an upward thrust to the reversing spring 51, forcing it to rotate around its reversing axis 52. This rotation causes its first end to disengage from the reversing slot 55 at the tail of the limiting tongue 41. Once disengaged, the limiting tongue 41 quickly ejects outwards under the strong force of the limiting torsion spring 43, restoring its limiting function. This ingenious mechanical design achieves automatic reset of the limiting function, preparing for the next telescopic locking cycle.

[0026] For telescopic sleeves with three or more sections, in order to achieve automated sequential control of layer-by-layer extension from the outside to the inside and layer-by-layer retraction from the inside to the outside, this utility model adds a telescopic sequence adjustment component 6. The telescopic sequence adjustment component 6 consists of three key components: an extension sequence spring pin 61, a sequence limiting hole 62, and a retraction sequence spring pin 63.

[0027] The extension sequence spring pin 61 is only located at the bottom of the innermost inner tube 2. The sequence limiting hole 62 is located at the bottom of all inner tubes 2. The retraction sequence spring pin 63 is located on the upper part of the outer sleeves other than the innermost inner tube 2 and the second innermost inner tube 2, and extends through the sleeve into the tube. Specifically, in a three-section sleeve embodiment, the retraction sequence spring pin 63 is located on the upper part of the outer tube 1, and extends through the outer tube 1 into the interior of the outer tube 1. The first inner tube 21 located in the second outermost layer and the second inner tube 22 located inside the first inner tube are not provided with the retraction sequence spring pin 63.

[0028] A method for adjusting the length of a telescopic sleeve includes the following steps: During the process of adjusting the telescopic sleeve from its shortest state to its longest state, the user only needs to continuously pull the innermost inner tube (e.g., the second inner tube 22). First, the first inner tube 21 is pulled out of the outer tube 1. When the limiting tongue 41 of the first inner tube 21 passes the reversing point 54 of the first middle sleeve 311, the function of the limiting component 4 of the first inner tube 21 is released (the principle is the same as the aforementioned two-section sleeve). Continue to pull the innermost inner tube; at this time, the extension sequence spring pin 61 located at the bottom of the innermost inner tube rises accordingly. When the extension sequence spring pin 61 passes the first middle sleeve 311, it is squeezed by the inner wall of the first middle sleeve 311, thereby exiting the sequence limiting hole 62 at the lower part of the first inner tube 21 where it is currently located.

[0029] Almost simultaneously, the retraction sequence spring pin 63, located on the upper part of the outer tube 1, inserts itself into the sequence limiting hole 62 of the first inner tube 21, which was just exposed due to the withdrawal of the extension sequence spring pin 61. This insertion action locks the first inner tube 21 at its maximum length extended from the outer tube 1.

[0030] Subsequently, the innermost inner tube is pulled up again, and the second inner tube 22 begins to be pulled out of the first inner tube 21. When the second inner tube 22 is pulled out to its maximum length from the first inner tube 21, and stops before its own limiting tongue 41 passes the reversing point 54 of the innermost middle sleeve, it is positioned by its own limiting component 4 and the first inner tube limiting hole 12 on the wall of the first inner tube 21. At this point, the entire telescopic sleeve has completed its sequential elongation from the outside to the inside.

[0031] During the adjustment of the telescopic sleeve from its longest to its shortest state, first, slightly lift the innermost inner tube 22 upwards, causing its limiting tongue 41 to pass the reversing point 54 of the innermost middle sleeve, thereby releasing the function of the limiting component 4 of the innermost inner tube 22. Then, press the innermost inner tube 22, and it and the second positioning sleeve 322 at its bottom will move downwards together, entering the bottom of the secondary inner tube (first inner tube 21). During this process, the second positioning sleeve 322 of the innermost inner tube 22 will push the retraction sequence spring pin 63 on the upper part of the outer tube 1 out of the sequence limiting hole 62 of the first inner tube 21, releasing its locking of the first inner tube 21. When the innermost inner tube 22 descends to touch the bottom of the second innermost inner tube 21, the second end of the reversing spring 51 of the innermost inner tube 22 touches the bottom of the second innermost inner tube 21, causing the reversing spring 51 to move, so that its first end is disengaged from the reversing slot 55 of the limiting tongue 41, and the limiting function of the innermost inner tube 22 is restored.

[0032] Next, continue pressing the innermost inner tube 22. The next innermost inner tube (first inner tube 21) and its first positioning sleeve 321 move downwards and enter the bottom of the outer tube 1. When the bottom of the next innermost inner tube 21 touches the bottom of the outer tube 1, the second end of the reversing spring 51 of the next innermost inner tube 21 touches the bottom of the outer tube 1, causing the reversing spring 51 to move, disengaging its first end from the reversing slot 55 of the limiting tongue 41 of the next innermost inner tube 21, and restoring the limiting function of the next innermost inner tube 21. Finally, the entire sleeve is retracted sequentially from the inside to the outside.

[0033] The head of the limiting tongue 41 is optimized with a wedge-shaped structure. Its outer surface is a smooth arc transition surface, which allows the limiting tongue 41 to slide smoothly along the inner wall of the outer sleeve when it moves upward with the inner tube 2, and to smoothly extend and engage with the limiting hole 12 of the outer sleeve using the inclined surface. When the sleeve is subjected to a downward force, the limiting tongue 41 is firmly locked by the edge of the limiting hole 12 of the outer sleeve, providing reliable load-bearing support and preventing the sleeve from accidentally retracting.

[0034] The reversing slot 55 can be of different shapes, such as a rectangular groove or an arc groove, to ensure stability when engaged and appropriate force when disengaged.

[0035] In terms of material selection, each sleeve can be made of metal (such as aluminum alloy, steel) or high-strength engineering plastics to ensure sufficient structural strength and wear resistance. The limiting torsion spring 43 and the reversing torsion spring 53 need to be calculated and selected according to the specific stress conditions, and appropriate spring steel wire specifications and heat treatment processes need to be selected.

[0036] A connector is typically located at the top of the innermost sleeve. This connector is used to connect the entire telescopic sleeve device to a component that requires height or angle adjustment, such as table or chair legs, or other mechanical support components. The connector can be designed in various forms to suit specific applications, such as threaded joints, flanges, and quick-release couplings, greatly enhancing the device's versatility. Figure 6 As shown, this device can also be used for angle adjustment of the sunshade 7.

[0037] Furthermore, the structure of the telescopic sleeve assembly is not limited to a completely enclosed tubular shape. In some applications, a non-completely enclosed groove structure can be used. Multiple such telescopic sleeve grooves can also be connected laterally in parallel. For example, when used as a telescopic ladder, telescopic sleeve grooves of the same level can be connected laterally at intervals multiple times, which not only increases the stability and safety of the entire ladder, but also allows for setting a suitable step distance, making it convenient for users to climb.

[0038] In terms of manufacturing process, the sleeve needs to be machined to ensure a high degree of smoothness on the inner wall to ensure smooth sliding of the limiting tongue 41 and each spring pin, reducing wear and jamming. The edges of the limiting holes 12 and 13 usually need to be appropriately chamfered or blunted, which facilitates the sliding of the head of the limiting tongue 41 and provides a robust and reliable locking surface for the limiting tongue 41, improving its service life. The machining and assembly precision requirements of all hinge points (such as the limiting shaft 42 and the reversing shaft 52) ​​are high, ensuring that the components can rotate flexibly without excessive gaps or looseness, so as to guarantee the accuracy and consistency of the operation.

[0039] To adapt to different load requirements, key components of the device can be specifically reinforced. For example, for applications requiring the support of greater weight, the size of the limiting tongue 41 can be appropriately increased to enhance its strength, a stronger torsion spring can be used to provide greater locking force, or more wear-resistant and higher-strength materials can be used to manufacture key parts. These design variations based on the same principle are all within the protection scope of this utility model.

[0040] Another significant advantage of this device is its ease of maintenance. Due to its modular and integrated design, when a component fails, it can usually be replaced individually without scrapping the entire device. In particular, the limit assembly 4, reversing assembly 5, and telescopic sequence adjustment assembly 6, all integrated into the control area at the bottom of the inner tube 2, can be inspected or replaced by disassembling the relevant structures at the bottom of the inner tube 2, which greatly reduces subsequent maintenance costs.

[0041] The technical features of the present invention are compared with those of the prior art as follows:

[0042] In summary, this utility model integrates a limiting component 4 and a reversing component 5 within its core control area, and adds a telescopic sequence adjustment component 6 for multi-section sleeves, supplemented by auxiliary structures such as the middle sleeve 31 and the positioning sleeve 32, thus constructing an extremely sophisticated and efficient mechanical linkage system. This system not only perfectly solves the inherent problem of having to operate multi-section telescopic sleeves section by section, achieving fully automatic sequential telescopic movement under a single continuous action, but its purely mechanical solution also endows the device with a series of outstanding advantages such as high reliability, long lifespan, low cost, and easy maintenance. By adjusting the number of layers in the sleeve 2, it can flexibly adapt to different telescopic range requirements; and the diverse connector designs and tubular and grooved structural options enable its wide application in various fields such as furniture, industrial equipment, sports equipment, and outdoor products, demonstrating excellent practical value and broad market prospects.

[0043] As is known from common technical knowledge, this utility model can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the above-disclosed embodiments are merely illustrative in all respects and are not the only ones. All modifications within the scope of this utility model or its equivalents are included in this utility model.

Claims

1. A telescopic sleeve length adjustment device, characterized in that, It includes a telescopic sleeve assembly, which includes an outer tube (1) as an outer sleeve and at least one inner tube (2) nested inside the outer tube (1). The innermost inner tube does not have a limiting hole (12), while the outermost sleeve has at least one limiting hole (12) in the second innermost inner tube. All limiting holes (12) are arranged along the sleeve axis to allow the limiting tongue (41) to extend for length positioning. Inside the sleeve with the limiting hole (12), the bottom of the nearest inner tube (2) is provided with a control area. The control area is provided with a limiting component (4) and a reversing component (5). The limiting component (4) includes a limiting tongue (41), a limiting shaft (42), and a limiting torsion spring (43). The limiting tongue (41) and the limiting torsion spring (43) are hinged to the lower part of the inner tube (2) through the limiting shaft (42). The limiting torsion spring (43) acts on the limiting tongue (41) to make the head of the limiting tongue (41) tend to extend outward into the limiting hole (12). The reversing assembly (5) includes a reversing spring (51), a reversing shaft (52), and a reversing torsion spring (53). The reversing spring (51) and the reversing torsion spring (53) are hinged to the control area through the reversing shaft (52). The first end of the reversing spring (51) acts on the tail of the limiting tongue (41) to selectively maintain or release the retracted state of the limiting tongue (41).

2. The telescopic sleeve length adjustment device according to claim 1, characterized in that, It also includes a middle sleeve (31) and a positioning sleeve (32). The middle sleeve (31) covers the top inner and outer walls of the outer sleeve except for the innermost inner tube, and the positioning sleeve (32) covers the bottom of the outer wall of the inner tube (2) except for the outer tube (1). The middle sleeve (31) and the positioning sleeve (32) are clamped together between adjacent inner and outer sleeves to maintain the axial alignment of the sleeve and limit the maximum extension length.

3. The telescopic sleeve length adjustment device according to claim 1, characterized in that, The inner wall of the middle sleeve (31) of the sleeve with a limiting hole is provided with a reversing point (54). The reversing point (54) is used to squeeze the head of the limiting tongue (41) to rotate inward to the retracted state when the limiting tongue (41) moves upward past its position. The tail of the limiting tongue (41) is provided with a reversing groove (55). The first end of the reversing spring (51) is inserted into the reversing groove (55) to keep the limiting tongue (41) in the retracted state.

4. The telescopic sleeve length adjustment device according to claim 1, characterized in that, The head of the limiting tongue (41) is a wedge-shaped structure, with its outer surface being an arc-shaped transition surface for smooth sliding along the inner wall of the sleeve, and its inner surface being used to be stuck by the edge of the limiting hole (12).

5. The telescopic sleeve length adjustment device according to claim 1, characterized in that, The inner tube (2) with the control area has an opening at the bottom, and the outer sleeve has a closed tube bottom at the bottom. The second end of the reversing spring (51) extends downward out of the opening and is used to be squeezed by the tube bottom when the inner tube (2) moves to the bottom of its outer sleeve, thereby releasing the first end of the reversing spring (51) from the retracted state of the limiting tongue (41).

6. A telescopic sleeve length adjustment device according to any one of claims 1 to 5, characterized in that, The inner tube (2) has at least two layers; the telescopic sequence adjustment assembly (6) includes an extension sequence spring pin (61), a sequence limiting hole (62), and a retraction sequence spring pin (63); wherein, the extension sequence spring pin (61) is only provided at the bottom of the innermost inner tube; the sequence limiting hole (62) is provided at the bottom of all inner tubes (2); the retraction sequence spring pin (63) is provided at the top of the outer sleeves other than the innermost and second innermost inner tubes, and extends into the tube through the sleeve wall.

7. The telescopic sleeve length adjustment device according to claim 1, characterized in that, The top of the innermost sleeve is provided with a connector for connecting furniture legs or mechanical support components.

8. The telescopic sleeve length adjustment device according to claim 1, characterized in that, The telescopic sleeve is a tubular structure or a non-completely enclosed groove structure.

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