Extension ladder

Abstract

The invention relates to an extension ladder which comprises an extension ladder section and ladder foot sections, the extension ladder section comprises at least two stages of ladder frames in telescopic fit, each ladder frame pipe comprises a first arc side plate, a straight side plate and a second arc side plate, one end of each straight side plate is connected with the corresponding first arc side plate, and the other end of each straight side plate is connected with the corresponding second arc side plate. A first arc angle is formed at the joint of the straight side plate and the first arc side plate, and a second arc angle is formed at the joint of the straight side plate and the second arc side plate, so that a ladder frame pipe with a bread-shaped cross section is defined; the surfaces of the stepping sticks are arc surfaces convenient to tread, and the sizes of the stepping sticks of the telescopic ladder sections are increased along with the increase of the sizes of the ladder frame pipes. The cross section of the ladder frame pipe is in a bread shape, and a stable structure is formed through combination of the first arc side plate, the straight side plate and the second arc side plate. According to the structure, the torsion resistance of the ladder frame pipe is obviously improved, and the stability and the safety of the ladder are ensured.

Description

Technical Field

[0001] The present invention relates to a telescopic ladder. Background Art

[0002] A telescopic ladder is a common tool product, widely used in households, engineering and other fields. Its portability and adjustable length make it an ideal choice for high-altitude operations, repairs, cleaning and other work. However, the telescopic ladders currently sold on the market still have some technical limitations, which affect their performance, safety and user experience.

[0003] The side frames of existing telescopic ladders usually adopt round tube designs. Although this design simplifies the production process to a certain extent, due to the weak torsional resistance of round tubes, the ladder is prone to deformation or shaking during use, affecting its stability and safety.

[0004] The sizes of each step bar of existing telescopic ladders are the same, and most of them adopt flat designs. This structure not only provides poor comfort when stepping on, but also limits the load-bearing capacity of the step bar. Especially during high-intensity operations, there may be potential safety hazards.

[0005] Traditional telescopic ladders mostly adopt a step-by-step folding method, and some products support one-key folding. However, the one-key folding speed is relatively fast, and it is easy to cause accidental injuries such as pinching hands due to the rapid contraction of the ladder frame tubes during the operation process, resulting in insufficient safety. Summary of the Invention

[0006] The purpose of the present invention is to provide a telescopic ladder that enhances the torsional resistance of the ladder frame and improves the user's stepping comfort.

[0007] The purpose of the present invention is achieved as follows:

[0008] A telescopic ladder includes telescopic ladder sections and ladder foot sections. The telescopic ladder sections include at least two levels of ladder frames that are telescopically fitted. Each level of ladder frame includes step bars, brackets and ladder frame tubes. The brackets are provided with insertion channels that penetrate up and down. Connecting heads are provided on the side parts of the brackets. At least four mating bumps are spaced apart on the inner wall of the insertion channels. An inward flange extending towards the center of the insertion channel is provided at the upper port of the insertion channel;

[0009] The upper end of each ladder frame tube passes through the lower port of the insertion channel and is inserted into the insertion channel of the corresponding bracket and abuts against the inward flange, realizing the connection between the ladder frame tube and the bracket. The mating bumps reduce the mating gap between the ladder frame tube and the insertion channel of the bracket. A descending device is provided at the lower end of each ladder frame tube;

[0010] The step bars are placed between the ladder frame tubes, and the ends of the step bars are respectively connected to the corresponding connecting heads;

[0011] The ladder frame tube of the upper-level ladder frame is sleeved inside the ladder frame tube of the lower-level ladder frame, and a folding mechanism is provided between the upper-level ladder frame and the lower-level ladder frame, and the folding mechanism locks or releases the unfolded state between the upper-level ladder frame and the lower-level ladder frame;

[0012] The ladder foot section includes tread bars, brackets and ladder foot tubes. The brackets are arranged on the ladder foot tubes, the tread bars are placed between the ladder foot tubes, and the ends of the tread bars are respectively connected to the connecting heads of the corresponding brackets;

[0013] The ladder frame tube of the last-level ladder frame is sleeved inside the ladder foot tube of the ladder foot section;

[0014] The size of the ladder frame tube of the upper-level ladder frame is smaller than the size of the ladder frame tube of the lower-level ladder frame, and the size of the ladder frame tube of the last-level ladder frame is smaller than the size of the ladder foot tube;

[0015] The ladder frame tube includes a first arc side plate, a straight side plate and a second arc side plate. One end of the straight side plate is connected to the first arc side plate, and the other end of the straight side plate is connected to the second arc side plate. Moreover, a first arc angle is formed at the connection between the straight side plate and the first arc side plate, and a second arc angle is formed at the connection between the straight side plate and the second arc side plate, thus enclosing a ladder frame tube with a "bread-like" cross-section;

[0016] The surface of the tread bar is an arc surface for easy stepping, and the size of the tread bar of the telescopic ladder section increases as the size of the ladder frame tube increases.

[0017] The ladder frame tube adopts a design with a "bread-like" cross-section. Through the combination of the first arc side plate, the straight side plate and the second arc side plate, a stable structure is formed. Compared with the traditional round tube design, this structure significantly improves the anti-torsion ability of the ladder frame tube, ensures the stability and safety of the ladder, especially performs more excellently under high-load working conditions.

[0018] A descending device is provided at the lower port of each ladder frame tube. By effectively controlling the contraction speed of the ladder frame, the risk of pinching hands caused by the too fast speed during the traditional one-key folding process is avoided. At the same time, at least four mating convex blocks are added to the inner wall of the insertion channel of the bracket. The mating convex blocks reduce the mating gap between the ladder frame tube and the insertion channel of the bracket, further improving the safety. Moreover, this optimized design effectively improves the anti-torsion ability and assembly quality of the ladder frame and extends the service life of the product.

[0019] The surface of the tread bar is designed as an arc shape, increasing the comfort of foot contact and reducing the fatigue during long-term use. At the same time, the size of the tread bar increases step by step as the size of the ladder frame tube increases. The tread bars of different sizes are configured corresponding to different ladder frame tubes, improving the load-bearing capacity and ensuring safety at different use heights.

[0020] Through optimizing the structural design, this telescopic ladder is not only applicable to general household operations but also capable of meeting the high-intensity operation requirements in professional engineering. The improvement in anti-torsion ability, load-bearing capacity, and safety performance enables it to adapt to more complex scenarios, enhancing the applicability of the product.

[0021] The object of the present invention can also be solved by the following technical measures:

[0022] Further, the tread bar includes an arc panel, a right-angle plate, and an inclined side plate. One end of the arc panel is connected to the right-angle plate, and the other end of the arc panel is connected to the inclined side plate, thus enclosing a tread bar with a "T-shaped" cross-section. The surface of the arc panel is the arc surface, and the arc surface is provided with concave and convex anti-slip ribs at intervals.

[0023] The tread bar adopts a "T-shaped" cross-section design, where the surface of the arc panel is set to be arc-shaped, conforming to the sole structure and providing a more comfortable stepping experience. By setting the concave and convex anti-slip ribs, the anti-slip performance of the tread bar surface is effectively increased, reducing the risk of slipping when used in a slippery environment.

[0024] Tread bars of corresponding sizes are equipped for different ladder frame tubes, and the width of the tread bar increases step by step with the size of the ladder frame tube, enhancing the load-bearing capacity of each level of the tread bar. This design better meets the load-bearing performance requirements when the height of the ladder increases, thus making the operation of climbing up and down the ladder safer and more stable, suitable for a variety of working scenarios.

[0025] The arc-shaped stepping surface not only conforms to the sole structure but also reduces the pressure on the feet during long-term operations, significantly enhancing the comfort of the user. This design is particularly suitable for high-altitude working scenarios that require long-term standing or climbing.

[0026] By setting the concave and convex anti-slip ribs at intervals on the arc panel, the operation safety of the user in various complex environments is effectively improved, especially significantly reducing the risk of slipping in rainy days or on oily sites. In addition, the combined structure of the arc surface, right-angle plate, and inclined side plate provides a more stable support effect, further enhancing the overall safety.

[0027] The design of tread bars with different widths and sizes can not only meet the needs of household use but also cope with professional scenarios with higher requirements such as engineering construction. As the size of the ladder frame increases, the width of the tread bar increases synchronously, providing stable support for the user when operating at different heights and significantly improving the versatility of the ladder.

[0028] Further, the descent control device includes a bottom cover, the bottom cover is arranged at the lower port of the ladder frame tube, and the bottom cover is provided with air holes.

[0029] By setting a bottom cover with air holes at the lower port of the ladder frame tube, the descent control device can effectively regulate the air flow speed, thereby slowing down the speed of the ladder frame tube during the contraction process and avoiding the problems of pinching hands or impacts caused by too fast contraction speed. This design significantly improves the safety of using the ladder, especially suitable for scenarios that require frequent folding and unfolding.

[0030] The setting of the bottom cover plays a protective role for the ladder frame tube, avoiding edge wear or deformation caused by frequent use. At the same time, the air hole design reduces the impact of air resistance on the ladder frame tube, further protecting the mating part of the ladder frame tube and the bracket, and extending the service life of the overall device.

[0031] The addition of the descent control device makes the folding process of the ladder frame tube smoother and more controllable. Users don't need to worry too much about the discomfort or danger caused by too fast folding speed. This smooth folding experience enhances users' confidence and satisfaction in using the product, suitable for both household and professional use scenarios.

[0032] The design of opening air holes on the bottom cover has a certain degree of adjustability. By adjusting the size or quantity of the air holes, it can flexibly adapt to the requirements of ladder frame tubes of different models and sizes, thus increasing the versatility and applicability of the product.

[0033] During the folding process of the ladder frame tube, the descent control device slows down the air flow speed through the air hole design, avoiding the impact noise that may occur during rapid contraction. This improvement not only enhances the comfort during use but also provides a quieter working environment for users.

[0034] Furthermore, an inward flanging extending towards the center direction of the insertion channel is provided at the upper port of the insertion channel. The ladder frame tube is provided with a blocking block. The ladder frame tube of the upper-level ladder slides along the inner cavity of the ladder frame tube of the lower-level ladder until the blocking block abuts against the inward flanging, and the ladder frame tubes of the upper-level and the lower-level are in a fully unfolded state.

[0035] The inner wall of the insertion channel of the bracket is provided with an inward flanging, which is used in cooperation with the blocking block on the ladder frame tube, effectively restricting the sliding range of the ladder frame tube of the upper level. When the blocking block abuts against the inward flanging, the ladder frame tubes of each level of the ladder are in a fully unfolded state. This design enhances the stability of the ladder after unfolding and prevents the ladder frame tube from detaching.

[0036] The cooperation between the inward flanging and the blocking block can not only stabilize the unfolded state of the ladder frame tube but also effectively prevent the ladder frame tube from accidentally detaching due to external forces, significantly improving the safety of using the ladder, especially more reliable during high-altitude operations.

[0037] The design of the inward flanging and the blocking block has high versatility, can adapt to ladder frame tubes of different sizes, and has a simple structure, which is easy for modular production and assembly. This optimized design reduces the production cost and at the same time improves the market adaptability of the product.

[0038] The innovative design of the inward flanging and the blocking block effectively solves the problems of easy slippage and instability during the unfolding process of traditional ladders, significantly improving the safety and usability of the ladders.

[0039] Furthermore, it also includes a shim with good toughness and wear resistance. The shim is arranged on the side wall of the ladder frame tube, and the shim forms the blocking block.

[0040] By arranging a shim with good toughness and wear resistance on the side wall of the ladder frame tube to form a blocking block, it can effectively prevent the ladder frame tube from slipping out during the stretching process. When the shim touches the inward flanging of the bracket of the next-level ladder frame, the ladder frame tube automatically stops stretching, realizing a reliable anti-slip function, greatly improving the safety performance of the ladder, especially being prominent in high-frequency usage scenarios.

[0041] The direct anti-slip structure of the traditional ladder frame tube is prone to wear due to frequent use, increasing the cost of replacing components. By using a wear-resistant shim as the anti-slip structure, not only the service life of the ladder frame tube is extended, but also the wear risk is reduced, thereby reducing the subsequent maintenance cost and improving the durability of the ladder.

[0042] The setting of the shim can eliminate part of the gap between the upper-level ladder frame tube and the lower-level ladder frame tube, reducing the shaking or noise problems caused by looseness. This gap optimization design improves the overall stability of the ladder, making it more stable and safe during use.

[0043] The shim plays a stable guiding role during the stretching process of the ladder frame tube, preventing the ladder frame tube from shifting or jamming, making the stretching of the ladder smoother and more efficient.

[0044] The shim with good toughness can, while preventing slippage, flexibly adapt to stretching actions of different intensities, and has strong wear resistance and is not easily damaged due to environmental changes (such as temperature or humidity). This design ensures that the ladder can maintain stable performance in a variety of complex usage environments.

[0045] The dual-functional design of the shim not only provides a protective effect but also takes into account the guiding and gap optimization functions, achieving multiple uses with one object. This design not only improves the functionality of the ladder but also further optimizes the overall structure, reflecting the efficiency and innovation of the design.

[0046] Furthermore, the center positions of the first arc-shaped side plate and the second arc-shaped side plate are on the same straight line. The radius of the first arc-shaped side plate is greater than the radius of the second arc-shaped side plate, and the radii of the first arc angle and the second arc angle are the same.

[0047] The ladder frame tube adopts a bread-shaped cross-section design, where the centers of the large arcs of the first arc side plate and the small arcs of the second arc side plate are on the same straight line, and the radii of the first arc angle and the second arc angle are the same. Such a structural design can effectively limit the relative rotation angle of the ladder frame tube, significantly enhance the anti-torsion ability of the ladder, and make it more stable and reliable during use.

[0048] The cross-section design of the bread-shaped tube is composed of two straight sides, arcs of different sizes, and four increasing rounded corners. This not only optimizes the stress distribution of the ladder frame tube but also reduces local stress concentration, thereby enhancing the overall load-bearing capacity and meeting the usage requirements of more complex working conditions.

[0049] The design of the large arc side, small arc side, and rounded corners of each ladder frame tube follows an increasing pattern, making the fitting clearance more precise. The reduction of the fitting clearance effectively reduces the looseness and wobbling that may occur during use, improving the usage accuracy and comfort of the ladder.

[0050] The arc side and rounded corner design of the ladder frame tube cross-section not only helps with anti-torsion but also improves the sliding smoothness between the ladder frame tubes. When users stretch or retract the ladder, they can enjoy a smoother operation experience while reducing jamming or blocking phenomena.

[0051] The design of the bread-shaped tube is unique, combining streamlined arc sides and rounded corners. This not only makes the appearance of the ladder more beautiful but also adds a sense of technology and professionalism to the product. Such a design better meets the aesthetic needs of users and further enhances the market attractiveness of the product.

[0052] The ladder frame tube with a bread-shaped cross-section can better resist deformation or damage that may occur during use through optimized structural design, extending the product life. At the same time, due to the improvement of anti-torsion ability and durability, the use and maintenance costs of the ladder are effectively reduced.

[0053] The unique bread-shaped cross-section design is significantly different from the common round tube structures on the market. It not only performs well in anti-torsion ability and load-bearing performance but also can adapt to more complex environments and professional application scenarios, further enhancing the market competitiveness of the product and the user experience.

[0054] Furthermore, the inner wall of the insertion channel of the bracket is provided with the mating convex blocks at the positions facing the first arc angle, the second arc angle, the first arc side plate, and the second arc side plate.

[0055] The inner wall of the insertion channel of the bracket is provided with mating bumps at the positions of the first arc angle, the second arc angle, the first arc side plate and the second arc side plate, making the fit between the bracket and the ladder frame tube closer. This multi-point fit design effectively disperses the torsional moment, further enhancing the anti-torsion ability of the ladder frame tube during use and ensuring that the ladder is more stable and reliable.

[0056] The reasonable distribution of the mating bumps at the key stress-bearing parts of the ladder frame tube can evenly disperse the pressure between the ladder frame tube and the bracket, avoiding wear or deformation caused by excessive local stress, thereby extending the service life of the ladder and reducing the daily maintenance cost.

[0057] By adding mating bumps at the positions of the first arc angle, the second arc angle and the arc side plate, the fit gap between the bracket and the ladder frame tube is effectively reduced, making the ladder free of shaking or deviation.

[0058] The multi-point mating bump design makes the ladder frame tube more stable when bearing lateral or torsional forces, reducing deformation or loosening problems caused by external forces. This design significantly improves the safety performance of the ladder, especially in high-load or high-frequency use scenarios.

[0059] The bumps are distributed at specific positions of the first arc angle, the second arc angle and the side plate, reflecting the refinement and scientific nature of the ladder design. This meticulous fit design improves the technical content of the product, making the ladder more competitive in the market.

[0060] The improvement of the mating bumps of the bracket enables the ladder to adapt to more complex working environments, including high-intensity construction scenarios or work occasions that require frequent stretching and retracting, providing users with a more stable and reliable use experience.

[0061] Compared with the traditional bracket design, this innovative design not only enhances the anti-torsion ability but also optimizes the overall structural stability and durability, making the product stand out among similar products and further enhancing the market competitiveness and user recognition.

[0062] Further, there are seven of the said mating bumps.

[0063] The mating bumps of the bracket are increased to seven, significantly improving the contact area and contact strength between the bracket and the ladder frame tube. The seven newly designed distributed mating bumps evenly cover the key parts, effectively restricting the relative rotation angle of the ladder frame tube and greatly enhancing the anti-torsion performance of the ladder.

[0064] Making the installation of the bracket more firm, reducing the fit gap, and at the same time enhancing the stability and reliability of the ladder under complex working conditions, suitable for a variety of high-intensity operation scenarios.

[0065] The matching protrusions of the bracket are reasonably distributed, and the force is evenly transmitted through seven matching points, avoiding assembly deformation problems caused by uneven force, and further improving the overall quality and durability of the product.

[0066] The newly added matching bumps are distributed in the key stress-bearing areas of the bracket, making the stress more uniform, reducing the wear rate between the ladder frame tube and the bracket, extending the service life of the ladder, and reducing the user's maintenance cost.

[0067] By adding matching protrusions, the bracket provides more stable support for the ladder frame tube, which can effectively reduce the risk of shaking caused by excessive gaps, especially when the ladder is fully extended, further improving the overall safety performance of the ladder.

[0068] The seven-point coordination design significantly improves the technical content of the ladder. It not only enhances the anti-torsion ability, but also optimizes the stability and service life, making it more competitive among similar products and meeting users' needs for high-performance ladders.

[0069] Furthermore, the connector of each bracket has a built-in accommodating cavity, each bracket is provided with a protrusion facing the upper ladder frame, and each ladder frame tube and ladder foot tube has a socket;

[0070] The folding mechanism includes an automatic folding mechanism and a manual folding mechanism. The penultimate step of the ladder foot section is provided with the manual folding mechanism, and the remaining ladder frames are provided with the automatic folding mechanism.

[0071] The manual folding mechanism includes a second lock pin, a second spring and a button, wherein the second lock pin is placed in the accommodating cavity of the penultimate bracket of the ladder foot section, the second spring is sleeved on the second lock pin, one end of the second spring abuts against the second lock pin, and the other end of the second spring abuts against the inner wall of the accommodating cavity, the second spring constitutes a reset mechanism for the second lock pin, and the button is connected to the second lock pin;

[0072] The elastic force of the second spring pushes the second locking pin through the bracket to be inserted into the sockets of the ladder foot tube and the last ladder frame tube in sequence, thereby locking the last ladder frame tube and the ladder foot tube in a telescopic state;

[0073] The automatic folding mechanism comprises a first lock pin, a first spring and a lever, wherein the first lock pin is placed in a receiving cavity of the bracket of the remaining ladder frame, the first spring is sleeved on the first lock pin, one end of the first spring abuts against the first lock pin, and the other end of the first spring abuts against the inner wall of the receiving cavity, the first spring constitutes a reset mechanism for the first lock pin, one end of the lever is connected to the first lock pin, and the other end of the lever extends out of the step to form a toggle portion;

[0074] The elastic force of the first spring pushes the first locking pin through the bracket and inserts into the sockets of the two adjacent ladder frame tubes in sequence, thereby locking the telescopic state of the two adjacent ladder frame tubes;

[0075] The button is pressed, and the button overcomes the elastic force of the second spring to drive the second lock pin to move, and the second lock pin moves away from the socket of the last ladder frame tube and the ladder foot tube, so that the last ladder frame tube and the ladder foot tube are in a free state;

[0076] The last ladder frame tube slides into the inner cavity of the ladder foot tube under the action of gravity;

[0077] At the same time, under the action of gravity, the toggle part of the upper ladder frame of the telescopic ladder section touches the raised part of the lower ladder frame, and the toggle part overcomes the elastic force of the first spring to drive the toggle rod to move, and the movement of the toggle rod drives the first locking pin to move away from the socket of the two adjacent ladder frame tubes, so that the two adjacent ladder frame tubes are in a free state;

[0078] The ladder frame tube of the upper level slides into the inner cavity of the ladder frame tube of the lower level under the action of gravity, and so on, to complete the stacking of the ladder frames of the telescopic ladder section, and an anti-pinch gap greater than the thickness of the palm is formed between the treads of the ladder frame of the upper level and the treads of the ladder frame of the lower level.

[0079] Users only need to press a button to activate the manual folding mechanism, and the ladder can be automatically folded without complicated operations, which simplifies the usage steps and greatly improves the user experience and operational convenience.

[0080] The telescopic ladder section achieves step-by-step stacking of the ladder frames through an automatic folding mechanism, using gravity to push the ladder frame tube to automatically slide into the ladder frame tube of the next level, eliminating the trouble of manual adjustment and significantly improving the folding efficiency.

[0081] During the folding process, the toggle portion of the upper ladder frame touches the raised portion of the lower ladder frame, automatically forming an anti-pinch gap that is larger than the thickness of the palm, effectively preventing the user's hands from being pinched and improving the safety performance of the ladder.

[0082] Both manual and automatic folding mechanisms are designed. The last ladder frame of the telescopic ladder section is stacked through the manual folding mechanism of the ladder foot section, ensuring that the user can accurately control the initial start-up; the remaining ladder frames are automatically stacked through the automatic folding mechanism, which has the advantages of both precision and efficiency.

[0083] The first locking pin and the second locking pin are both equipped with independent spring return mechanisms to ensure that when folded or unfolded, the locking pins can quickly return to their original positions and lock the ladder frame tube, thereby ensuring the stability and safety of the ladder.

[0084] The ladder fully utilizes gravity drive when folding, and the user does not need to manually push the ladder frame tube, which reduces the labor intensity of the user and is more suitable for scenes that are frequently used or require quick folding.

[0085] This design is suitable for a variety of scenarios such as home use and engineering construction, especially work environments that require frequent folding and unfolding, meeting users' comprehensive needs for convenience, safety and high efficiency.

[0086] By integrating manual and automatic folding mechanisms, anti-pinch gap design, and efficient operation processes, this innovative design significantly improves the technical level and user experience of telescopic ladders.

[0087] Furthermore, a handle is provided at the bottom of the second-to-last rung of the ladder foot section, the buttons are arranged on both sides of the handle, and both the rung of the first ladder frame and the second-to-last rung of the ladder foot section are provided with binding straps.

[0088] The contact area of the buttons is increased, making them easier to press compared to traditional designs, reducing the pressure on the hand when pressing, making user operation more relaxed and labor-saving, and further enhancing the user experience.

[0089] The newly added handle at the bottom of the second-to-last rung of the ladder foot section not only protects the buttons from external damage. In addition, the handle is convenient for users to grip when carrying, enhancing the portability and practicality of the ladder.

[0090] Binding straps are provided on both the rung of the first ladder frame and the second-to-last rung of the ladder foot section. After the ladder is folded, users can use the binding straps to fix the ladder to avoid a loose state, improving the neatness and safety of storage.

[0091] The handle design provides a convenient gripping point, making it more labor-saving for users to carry the ladder and reducing the risk of the ladder slipping due to lack of a gripping point, which is particularly suitable for scenarios where frequent movement and use are required.

[0092] The integrated design of the buttons and the handle, as well as the provision of binding straps, enables efficient and convenient operation from the use of the ladder to its folding and then to storage, greatly optimizing the user experience.

[0093] The addition of the handle and binding straps plays a good protective role during use and storage, preventing the buttons or ladder frames from being damaged due to impact or friction, and extending the service life of the ladder.

[0094] Combined with the increased button area, the handle design that protects the buttons, and the convenient binding straps, this design further enhances the functionality of the product and the user experience, making it more attractive in the highly competitive ladder market.

[0095] The handle and binding straps enable the ladder to provide more convenient operation and safe storage in various scenarios such as outdoor work, home storage, and transportation, significantly improving its adaptability.

[0096] The beneficial effects of the present invention are as follows:

[0097] In the present invention, the ladder frame tube adopts a "bread-shaped" cross-section design, and a stable structure is formed by the combination of a first arc side plate, a straight side plate and a second arc side plate. Compared with the traditional round tube design, this structure significantly improves the torsion resistance of the ladder frame tube, ensures the stability and durability of the ladder, and performs better under particularly high-load operating conditions.

[0098] In the present invention, the surface of the step is designed to be arc-shaped, which increases the comfort of foot contact and reduces fatigue during long-term use. At the same time, the size of the step increases step by step with the increase of the size of the ladder frame tube. Different ladder frame tubes are equipped with steppers of corresponding sizes, which improves the load-bearing capacity and ensures safety at different use heights.

[0099] The present invention forms a blocking block by arranging a tough and wear-resistant blocking piece on the side wall of the ladder frame tube, which can effectively prevent the ladder frame tube from falling out during the stretching process. When the blocking piece hits the inner flange of the bracket of the next ladder frame, the ladder frame tube automatically stops stretching, realizing a reliable anti-falling function, greatly improving the safety performance of the ladder, especially in high-frequency use scenarios.

[0100] In the present invention, the inner wall of the insertion channel of the bracket is provided with matching protrusions at the positions of the first arc angle, the second arc angle, the first arc side plate and the second arc side plate, so that the bracket and the ladder frame tube are more closely matched. This multi-point matching design effectively disperses the torsional moment, further enhances the anti-twisting ability of the ladder frame tube during use, and ensures that the ladder is more stable and reliable.

[0101] In the present invention, during the folding process, the toggle portion of the upper ladder frame touches the raised portion of the lower ladder frame, automatically forming an anti-pinch gap greater than the thickness of a palm, effectively preventing the user's hands from being pinched, and improving the safety performance of the ladder.

[0102] The present invention allows the user to simply press a button to activate the manual folding mechanism, and the telescopic ladder sections can be stacked step by step through the automatic folding mechanism. Gravity is used to push the ladder frame tube to automatically slide into the ladder frame tube of the next step, thus eliminating the trouble of manual adjustment and significantly improving the folding efficiency. The ladder can be automatically folded without complicated operations, thus simplifying the use steps and greatly improving the user experience and operational convenience.

[0103] In the present invention, the upper "bread-shaped" ladder frame tube is inserted into the lower "bread-shaped" ladder frame tube through the insertion channel of the bracket, and seven matching protrusions form multi-point support and constraints for the ladder frame tube. The distribution of the matching protrusions is adapted to the shape of the ladder frame tube, providing comprehensive anti-torsion constraints. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 Schematic diagram of a telescopic ladder (folded state).

[0105] Figure 2Another perspective view of the retractable ladder (folded state).

[0106] Figure 3 Front view of the retractable ladder (folded state).

[0107] Figure 4 For Figure 3 Enlarged view of part A of

[0108] Figure 5 For Figure 3 Enlarged view of part B of

[0109] Figure 6 For Figure 3 Cross-sectional view of

[0110] Figure 7 Schematic diagram of the retractable ladder (extended state).

[0111] Figure 8 Another perspective view of the retractable ladder (extended state).

[0112] Figure 9 Front view of the retractable ladder (extended state).

[0113] Figure 10 Cross-sectional view of the retractable ladder.

[0114] Figure 11 For Figure 10 Enlarged view of part C of

[0115] Figure 12 For Figure 10 Enlarged view of part D of

[0116] Figure 13 Schematic diagram of the ladder frame.

[0117] Figure 14 Assembly drawing of the ladder frame.

[0118] Figure 15 Cross-sectional schematic diagram of the ladder frame tube.

[0119] Figure 16 Cross-sectional schematic diagram of the tread bar.

[0120] Figure 17 Schematic diagram of the bracket.

[0121] Figure 18 Another perspective view of the bracket.

[0122] Figure 19 Schematic diagram of the bracket.

[0123] Figure 20 Another perspective view of the bracket.

[0124] Figure 21 Another perspective schematic diagram of the bracket. Specific implementation manner

[0125] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0126] Embodiment, in combination with Figures 1 to 21 As shown, a telescopic ladder includes a telescopic ladder section 1 and a ladder foot section 2. The telescopic ladder section 1 includes at least two levels of telescopically cooperating ladder frames 3. Each level of ladder frame 3 includes a tread bar 4, a bracket 5, and a ladder frame tube 6.

[0127] The bracket 5 is provided with an insertion channel 52 that penetrates up and down. A connection head 55 is provided on the side of the bracket 5. At least four mating bumps 51 are spaced apart on the inner wall of the insertion channel 52. The upper port of the insertion channel 52 is provided with an inwardly turned edge 53 that extends towards the center of the insertion channel 52.

[0128] The upper end of each ladder frame tube 6 passes through the lower port of the insertion channel 52 and is inserted into the insertion channel 52 of the corresponding bracket 5 and abuts against the inwardly turned edge 53 to realize the connection between the ladder frame tube 6 and the bracket 5. The mating bumps 51 reduce the mating gap between the ladder frame tube 6 and the insertion channel 52 of the bracket 5. The lower end of each ladder frame tube 6 is provided with a slow-down device.

[0129] The tread bar 4 is placed between the ladder frame tubes 6, and the ends of the tread bar 4 are respectively connected to the corresponding connection heads 55.

[0130] The ladder frame tube 6 of the upper-level ladder frame 3 is sleeved inside the ladder frame tube 6 of the lower-level ladder frame 3, and a closing mechanism is provided between the upper-level ladder frame 3 and the lower-level ladder frame 3. The closing mechanism locks or releases the unfolded state between the upper-level ladder frame 3 and the lower-level ladder frame 3.

[0131] The ladder foot section 2 includes a tread bar 4, a bracket 5, and a ladder foot tube 21. The bracket 5 is provided on the ladder foot tube 21. The tread bar 4 is placed between the ladder foot tubes 21, and the ends of the tread bar 4 are respectively connected to the connection heads 55 of the corresponding brackets 5.

[0132] The ladder frame tube 6 of the last-level ladder frame 3 is sleeved inside the ladder foot tube 21 of the ladder foot section 2.

[0133] The size of the ladder frame tube 6 of the upper-level ladder frame 3 is smaller than the size of the ladder frame tube 6 of the lower-level ladder frame 3, and the size of the ladder frame tube 6 of the last-level ladder frame 3 is smaller than the size of the ladder foot tube 21.

[0134] The ladder frame tube 6 includes a first arc side plate 61, a straight side plate 62 and a second arc side plate 63. One end of the straight side plate 62 is connected to the first arc side plate 61, and the other end of the straight side plate 62 is connected to the second arc side plate 63. Moreover, a first arc angle 64 is formed at the connection between the straight side plate 62 and the first arc side plate 61, and a second arc angle 65 is formed at the connection between the straight side plate 62 and the second arc side plate 63, thus enclosing the ladder frame tube 6 with a "bread-shaped" cross-section.

[0135] The surface of the tread bar 4 is an arc surface 411 for easy stepping, and the size of the tread bar 4 of the telescopic ladder section 1 increases as the size of the ladder frame tube 6 increases.

[0136] Further, the tread bar 4 includes an arc panel 41, a right-angle plate 42 and an inclined side plate 43. One end of the arc panel 41 is connected to the right-angle plate 42, and the other end of the arc panel 41 is connected to the inclined side plate 43, thus enclosing the tread bar 4 with a "T-shaped" cross-section. The surface of the arc panel 41 is the arc surface 411, and the arc surface 411 is provided with concave and convex anti-slip ribs 412 at intervals.

[0137] Further, the descent control device includes a bottom cover 7. The bottom cover 7 is arranged at the lower port of the ladder frame tube 6, and the bottom cover 7 is provided with air holes.

[0138] Further, an inward flanging 53 extending towards the center direction of the insertion channel 52 is provided at the upper port of the insertion channel 52 of the bracket 5. The ladder frame tube 6 is provided with a blocking block. The ladder frame tube 6 of the upper-level ladder frame 3 slides along the inner cavity of the ladder frame tube 6 of the lower-level ladder frame 3 until the blocking block abuts against the inward flanging 53, and the upper-level ladder frame tube 6 and the lower-level ladder frame tube 6 are in a fully extended state.

[0139] Further, it further includes a flap 300 with good toughness and wear resistance. The flap 300 is arranged on the side wall of the ladder frame tube 6, and the flap 300 forms the blocking block.

[0140] Further, the center positions of the first arc side plate 61 and the second arc side plate 63 are on the same straight line. The radius of the first arc side plate 61 is greater than the radius of the second arc side plate 63, and the radii of the first arc angle 64 and the second arc angle 65 are the same.

[0141] Further, the inner wall of the insertion channel 52 of the bracket 5 is provided with the mating convex blocks 51 at the positions facing the first arc angle 64, the second arc angle 65, the first arc side plate 61 and the second arc side plate 63.

[0142] Further, there are seven mating convex blocks 51.

[0143] Furthermore, the connector 55 of each bracket 5 has a built-in accommodating cavity 551, each bracket 5 is provided with a protrusion 54 facing the upper ladder frame 3, and each ladder frame tube 6 and ladder foot tube 21 has a socket;

[0144] The folding mechanism includes an automatic folding mechanism 8 and a manual folding mechanism 9. The penultimate step 4 of the ladder foot section 2 is provided with the manual folding mechanism 9, and the remaining ladder frames 3 are provided with the automatic folding mechanism 8;

[0145] The manual folding mechanism 9 includes a second lock pin 91, a second spring 92 and a button 93. The second lock pin 91 is placed in the accommodating cavity 551 of the penultimate bracket 5 of the ladder foot section. The second spring 92 is sleeved on the second lock pin 91. One end of the second spring 92 abuts against the second lock pin 91, and the other end of the second spring 92 abuts against the inner wall of the accommodating cavity 551. The second spring 92 constitutes a reset mechanism for the second lock pin 91. The button 93 is connected to the second lock pin 91.

[0146] The elastic force of the second spring 92 pushes the second locking pin 91 through the bracket 5 and sequentially inserts into the sockets of the ladder foot tube 21 and the last ladder frame tube 6, thereby locking the last ladder frame tube 6 and the ladder foot tube 21 in a telescopic state;

[0147] The automatic folding mechanism 8 comprises a first lock pin 81, a first spring 82 and a lever 83. The first lock pin 81 is placed in the accommodating cavity 551 of the bracket 5 of the remaining ladder frame 3. The first spring 82 is sleeved on the first lock pin 81. One end of the first spring 82 abuts against the first lock pin 81. The other end of the first spring 82 abuts against the inner wall of the accommodating cavity 551. The first spring 82 constitutes a reset mechanism for the first lock pin 81. One end of the lever 83 is connected to the first lock pin 81. The other end of the lever 83 extends out of the step 4 to form a toggle portion 831.

[0148] The elastic force of the first spring 82 pushes the first locking pin 81 through the bracket 5 and inserts into the sockets of the two adjacent ladder frame tubes 6 in sequence, thereby locking the telescopic state of the two adjacent ladder frame tubes 6;

[0149] Press the button 93, the button 93 overcomes the elastic force of the second spring 92 to drive the second lock pin 91 to move, and the second lock pin 91 moves away from the insertion of the last ladder frame tube 6 and the ladder foot tube 21, so that the last ladder frame tube 6 and the ladder foot tube 21 are in a free state;

[0150] The last ladder frame tube 6 slides into the inner cavity of the ladder foot tube 21 under the action of gravity;

[0151] At the same time, under the action of gravity, the toggle portion 831 of the upper ladder frame 3 of the telescopic ladder section 1 touches the protruding portion 54 of the lower ladder frame 3, and the toggle portion 831 overcomes the elastic force of the first spring 82 to drive the toggle rod 83 to move, and the movement of the toggle rod 83 drives the first locking pin 81 to move away from the sockets of the two adjacent ladder frame tubes 6, so that the two adjacent ladder frame tubes 6 are in a free state;

[0152] The ladder frame tube 6 of the upper level slides into the inner cavity of the ladder frame tube 6 of the lower level under the action of gravity, and so on, completing the stacking of the ladder frames 3 of the telescopic ladder section 1, and forming an anti-pinch gap 10 larger than the thickness of a palm between the treads 4 of the ladder frame 3 of the upper level and the treads 4 of the ladder frame 3 of the lower level.

[0153] Furthermore, a handle 100 is provided at the bottom of the penultimate rung 4 of the ladder foot section 2, the buttons 93 are provided on both sides of the handle 100, and the rung 4 of the first ladder frame 3 and the penultimate rung 4 of the ladder foot section 2 are both provided with binding belts 200.

[0154] The "bread-shaped" ladder frame tube 6 has the following significant advantages:

[0155] The "bread-like" design of the ladder frame tube 6 makes its appearance rounded and has no sharp edges, which is not only more beautiful, but also reduces potential harm to users during use, thereby improving safety and user experience.

[0156] The "bread-shaped" cross section of the ladder frame tube 6 is composed of a first arc side plate 61, a second arc side plate 63 and a straight side plate 62. The overall shape is symmetrical and the structure is compact. The arc distribution of the arc side plate increases the torsional rigidity of the tube, can effectively disperse the torque and avoid deformation of the tube.

[0157] The straight side plates 62 connect the arc side plates on both sides to form a solid supporting structure, thereby improving the bending strength of the ladder frame tube 6 and being able to withstand a higher load.

[0158] The arc surface design of the first arc side plate 61 and the second arc side plate 63 increases the contact area between the bracket 5 and the ladder frame tube 6, improves the matching stability, and reduces the shaking and displacement caused by the gap.

[0159] The design combining the curved surface and the straight edge enables the ladder frame tube 6 to resist the torsional force and the bending force at the same time, thus avoiding the instability caused by a single force mode during use.

[0160] Distribution characteristics of the mating protrusions 51:

[0161] The inner wall of the insertion channel 52 of the bracket 5 is provided with seven matching protrusions 51 at the key stress-bearing positions (the first arc angle 64, the second arc angle 65, the first arc side plate 61 and the second arc side plate 63) of the ladder frame tube 6. These protrusions are evenly distributed and precisely match the "bread-like" structure of the cross section of the ladder frame tube 6.

[0162] The mating relationship between the ladder frame tube 6 and the bracket 5:

[0163] The ladder frame tube 6 of this stage is inserted into the insertion channel 52 of the corresponding bracket 5 to realize the connection between the ladder frame tube 6 and the bracket 5. The seven mating bumps 51 form multi-point support and restraint on the ladder frame tube 6, and the distribution of the mating bumps 51 is adapted to the shape of the ladder frame tube 6, providing comprehensive anti-torsion restraint.

[0164] Reasons for enhanced anti-torsion ability:

[0165] The seven mating bumps 51 provide more contact points, which can more effectively limit the rotational freedom of the ladder frame tube 6 compared with traditional designs.

[0166] The mating bumps 51 cover the key parts of the arc corners and side plates, dispersing the torque to multiple support points and avoiding deformation or loosening caused by concentrated stress.

[0167] The mating bumps 51 are closely fitted with the ladder frame tube 6, reducing the assembly clearance and further enhancing the structural stability and anti-torsion performance.

[0168] The combination of the seven mating bumps 51 of the bracket 5 and the "bread-shaped" ladder frame tube 6 gives full play to the advantages of multi-point support and shape matching, greatly improving the anti-torsion ability of the ladder frame 3 and ensuring the stability and durability of the ladder frame 3 during use. Structural features of the tread bar 4:

[0169] Tread bars 4 of corresponding sizes are equipped for different ladder frame tubes 6. The width of the tread bar 4 increases step by step with the size of the ladder frame tube 6, enhancing the load-bearing capacity of each level of the tread bar 4. This design better meets the requirements for load-bearing performance when the height of the ladder increases.

[0170] Thus, the operation of going up and down the ladder is safer and more stable, suitable for a variety of working scenarios.

[0171] The arc-shaped tread surface not only fits the sole structure but also reduces the pressure on the feet during long-term operation, significantly improving the comfort of the user. This design is especially suitable for high-altitude working scenarios that require long-term standing or climbing.

[0172] By arranging concave and convex anti-slip ribs 412 at intervals on the arc-shaped panel 41, the operation safety of the user in various complex environments is effectively improved, especially significantly reducing the slipping risk in rainy days or oily sites.

[0173] Benefits of the handle 100:

[0174] The handle 100 not only protects the button 93 from external damage. In addition, the handle 100 is convenient for the user to grip during handling, enhancing the portability and practicality of the ladder.

[0175] Benefits of the increased contact area of the button 93:

[0176] The increased contact area of the button 93 makes it easier to press compared to traditional designs, reducing the pressure on the hand when pressing, making user operation more relaxed and labor-saving, and further enhancing the user experience.

[0177] Benefits of the tie strap 200:

[0178] Tie straps 200 are provided on both the tread bar 4 of the first-stage ladder frame 3 and the second-to-last tread bar 4 of the ladder foot section 2. After the ladder is folded, users can use the tie straps 200 to fix the ladder, preventing it from becoming loose, and improving the neatness and safety of storage.

[0179] Benefits of using the retaining piece 300:

[0180] By setting a retaining piece 300 with good toughness and wear resistance on the side wall of the ladder frame tube 6 to form a blocking block, when the retaining piece 300 touches the inward flange 53 of the bracket 5 of the next-stage ladder frame 3, the ladder frame tube 6 automatically stops stretching, achieving a reliable anti-disconnection function, greatly enhancing the safety performance of the ladder, especially prominent in high-frequency usage scenarios.

[0181] Using the wear-resistant retaining piece 300 as an anti-disconnection structure not only extends the service life of the ladder frame tube 6 but also reduces the wear risk, thereby reducing subsequent maintenance costs and improving the durability of the ladder.

[0182] The setting of the retaining piece 300 can eliminate part of the gap between the upper-stage ladder frame tube 6 and the lower-stage ladder frame tube 6, reducing the shaking or noise problems caused by looseness. This gap optimization design improves the overall stability of the ladder, making it more stable and safe during use.

[0183] The retaining piece 300 plays a stable guiding role during the stretching process of the ladder frame tube 6, preventing the ladder frame tube 6 from shifting or jamming, and making the ladder stretching smoother and more efficient.

[0184] Method for the unfolding operation of the extendable ladder

[0185] Check the ladder status

[0186] Place the ladder horizontally or stand it against the wall, untie the tie strap 200 that fixes the ladder, ensure that the ladder frame 3 and the ladder foot section 2 are not damaged, and that the button 93 and the locking pin are in normal working condition.

[0187] Gradually unfold the ladder frame 3

[0188] Starting from the ladder foot section 2, pull the last-stage ladder frame 3 upward so that the ladder frame tube 6 slides out of the inner cavity of the ladder foot tube 21.

[0189] When the ladder frame tube 6 moves upward to the limit position of the inner flange 53 of the bracket 5, the blocking block abuts against the inner flange 53 to ensure that the ladder frame 3 is fully unfolded.

[0190] At the same time, the second locking pin 91 is inserted into the sockets of the ladder foot tube 21 and the ladder frame tube 6 under the elastic force of the second spring 92 to lock the telescopic state.

[0191] Expand other ladder frames 3 in sequence

[0192] Lift the upper ladder frame pipe 6 step by step so that it can slide out from the lower ladder frame pipe 6.

[0193] When each ladder frame tube 6 moves to the limit position of the bracket 5, the blocking block abuts against the inner flange 53, and the first locking pin 81 is automatically inserted into the sockets of the two adjacent ladder frame tubes 6 under the elastic force of the first spring 82 to complete the locking.

[0194] Checking deployment stability

[0195] Confirm that each ladder frame 3 has been fully unfolded and locked, check whether the rungs 4 are stable, and ensure the safety of the ladder.

[0196] Adjust the use angle

[0197] Adjust the placement angle of the ladder foot section 2 as needed to keep the ladder in a stable state to ensure safe use.

[0198] Folding operation method of telescopic ladder

[0199] Start the manual folding mechanism 9

[0200] The buttons 93 arranged on both sides of the handle 100 are pressed to overcome the elastic force of the second spring 92, so that the second locking pin 91 is moved out from the sockets of the last ladder frame tube 6 and the ladder foot tube 21, thereby releasing the locking state.

[0201] Under the action of gravity, the last ladder frame tube 6 slowly slides into the inner cavity of the ladder foot tube 21 .

[0202] Triggering the automatic folding mechanism 8

[0203] When the last ladder frame 3 slides into the inner cavity of the ladder foot tube 21 , its moving portion 831 touches the protruding portion 54 of the bracket 5 connected to the penultimate step 4 of the ladder foot section 2 .

[0204] An anti-pinch gap 10 greater than the thickness of a palm is formed between the penultimate step 4 of the ladder foot section 2 and the step 4 of the last step ladder frame 3 to ensure safety.

[0205] The shifting portion 831 overcomes the elastic force of the first spring 82, drives the shifting rod 83 to move, and moves the first locking pin 81 out of the sockets of the two adjacent ladder frame tubes 6 to release the lock.

[0206] Step-by-step folding of ladder frame 3

[0207] Under the action of gravity, the penultimate ladder frame tube 6 slowly slides into the inner cavity of the last ladder frame tube 6 .

[0208] The above process is repeated, and the ladder frame tubes 6 are slid in step by step to complete the stacking of all the ladder frames 3.

[0209] Ensure anti-pinch safety

[0210] When the moving part 831 of each ladder frame 3 touches the raised part 54 of the ladder frame 3 of the next step, a safety anti-pinch gap 10 is formed to avoid pinching fingers during operation.

[0211] Complete the folding and fixing

[0212] After all the ladder frame tubes 6 are completely folded, the treads 4 of the first ladder frame 3 and the penultimate tread 4 of the ladder foot section 2 are fixed with the binding belt 200 to ensure that the ladder will not become loose during transportation or storage.

[0213] Check whether the handle 100 and the button 93 of the ladder are in normal condition.

Claims

1. A telescopic ladder, comprising a telescopic ladder section and a ladder foot section, wherein the telescopic ladder section comprises at least two levels of telescopic ladder frames, characterized in that: Each ladder frame comprises a step, a bracket and a ladder frame tube, the bracket is provided with a plug-in channel which passes through from top to bottom, a connector is provided on the side of the bracket, at least four matching protrusions are provided at intervals on the inner wall of the plug-in channel, and an upper end of the plug-in channel is provided with an inner flange extending toward the center of the plug-in channel; The upper end of each ladder frame tube passes through the lower port of the plug-in channel and is inserted into the plug-in channel of the corresponding bracket and abuts against the inner flange to achieve the connection between the ladder frame tube and the bracket. The matching protrusion reduces the matching clearance of the plug-in channel between the ladder frame tube and the bracket. The lower end of each ladder frame tube is provided with a slow-down device; The steps are placed between the ladder frame tubes, and the ends of the steps are connected to corresponding connectors respectively; The ladder frame tube of the upper ladder frame is sleeved in the ladder frame tube of the lower ladder frame, and a folding mechanism is provided between the upper ladder frame and the lower ladder frame, and the folding mechanism locks or releases the unfolded state between the upper ladder frame and the lower ladder frame; The ladder foot section includes a step rod, a bracket and a ladder foot tube, wherein the bracket is arranged on the ladder foot tube, the step rod is arranged between the ladder foot tubes, and the ends of the step rod are respectively connected to the connectors of the corresponding brackets; The ladder frame pipe sleeve of the last ladder frame is arranged in the ladder foot pipe of the ladder foot section; The size of the ladder frame tube of the upper ladder frame is smaller than the size of the ladder frame tube of the lower ladder frame, and the size of the ladder frame tube of the last ladder frame is smaller than the size of the ladder foot tube; The ladder frame tube comprises a first arc side plate, a straight side plate and a second arc side plate, one end of the straight side plate is connected to the first arc side plate, and the other end of the straight side plate is connected to the second arc side plate, and the connection between the straight side plate and the first arc side plate forms a first arc angle, and the connection between the straight side plate and the second arc side plate forms a second arc angle, thereby forming a ladder frame tube with a "bread-shaped" cross section; The surface of the step is an arc surface that is convenient for stepping on, and the size of the step of the telescopic ladder section increases as the size of the ladder frame tube increases.

2. The telescopic ladder according to claim 1, characterized in that: The pedal comprises an arc panel, a right-angle plate and a bevel plate, one end of the arc panel is connected to the right-angle plate, and the other end of the arc panel is connected to the bevel plate, thereby forming a pedal with a "T-shaped" cross-section, the surface of the arc panel is the arc surface, and the arc surface is provided with concave and convex anti-slip ribs at intervals.

3. The telescopic ladder according to claim 1, characterized in that: The slow-descent device comprises a bottom cover, which is arranged at the lower end of the ladder frame tube and has air holes.

4. The telescopic ladder according to claim 1, characterized in that: The ladder frame tube is provided with a blocking block, and the ladder frame tube of the upper ladder frame slides along the inner cavity of the ladder frame tube of the lower ladder frame until the blocking block abuts against the inner fold edge, and the ladder frame tube of the upper ladder frame and the ladder frame tube of the lower ladder frame are in a fully expanded state.

5. The telescopic ladder according to claim 4, characterized in that: It also includes a baffle with good toughness and wear resistance, which is arranged on the side wall of the ladder frame tube and forms the baffle block.

6. The telescopic ladder according to claim 1, characterized in that: The center position of the first arc side plate and the center position of the second arc side plate are on the same straight line, the radius of the first arc side plate is greater than the radius of the second arc side plate, and the radius of the first arc angle is the same as the radius of the second arc angle.

7. The telescopic ladder according to claim 1, characterized in that: The inner wall of the insertion channel of the bracket is provided with the matching protrusions at the position of the first arc angle, the position of the second arc angle, the position of the first arc side plate and the position of the second arc side plate.

8. The telescopic ladder according to claim 7, characterized in that: There are seven matching protrusions.

9. The telescopic ladder according to claim 1, characterized in that: Each bracket connector has a built-in accommodating cavity, each bracket is provided with a protrusion facing the upper ladder frame, and each ladder frame tube and ladder foot tube has a socket; The folding mechanism includes an automatic folding mechanism and a manual folding mechanism. The penultimate step of the ladder foot section is provided with the manual folding mechanism, and the remaining ladder frames are provided with the automatic folding mechanism. The manual folding mechanism includes a second lock pin, a second spring and a button, wherein the second lock pin is placed in the accommodating cavity of the penultimate bracket of the ladder foot section, the second spring is sleeved on the second lock pin, one end of the second spring abuts against the second lock pin, and the other end of the second spring abuts against the inner wall of the accommodating cavity, the second spring constitutes a reset mechanism for the second lock pin, and the button is connected to the second lock pin; The elastic force of the second spring pushes the second locking pin through the bracket to be inserted into the sockets of the ladder foot tube and the last ladder frame tube in sequence, thereby locking the last ladder frame tube and the ladder foot tube in a telescopic state; The automatic folding mechanism comprises a first lock pin, a first spring and a lever, wherein the first lock pin is placed in a receiving cavity of the bracket of the remaining ladder frame, the first spring is sleeved on the first lock pin, one end of the first spring abuts against the first lock pin, and the other end of the first spring abuts against the inner wall of the receiving cavity, the first spring constitutes a reset mechanism for the first lock pin, one end of the lever is connected to the first lock pin, and the other end of the lever extends out of the step to form a toggle portion; The elastic force of the first spring pushes the first locking pin through the bracket and inserts into the sockets of the two adjacent ladder frame tubes in sequence, thereby locking the telescopic state of the two adjacent ladder frame tubes; The button is pressed, and the button overcomes the elastic force of the second spring to drive the second lock pin to move, and the second lock pin moves away from the socket of the last ladder frame tube and the ladder foot tube, so that the last ladder frame tube and the ladder foot tube are in a free state; The last ladder frame tube slides into the inner cavity of the ladder foot tube under the action of gravity; At the same time, under the action of gravity, the toggle part of the upper ladder frame of the telescopic ladder section touches the raised part of the lower ladder frame, and the toggle part overcomes the elastic force of the first spring to drive the toggle rod to move, and the movement of the toggle rod drives the first locking pin to move away from the socket of the two adjacent ladder frame tubes, so that the two adjacent ladder frame tubes are in a free state; The ladder frame tube of the upper level slides into the inner cavity of the ladder frame tube of the lower level under the action of gravity, and so on, to complete the stacking of the ladder frames of the telescopic ladder section, and an anti-pinch gap greater than the thickness of the palm is formed between the treads of the ladder frame of the upper level and the treads of the ladder frame of the lower level.

10. The telescopic ladder according to claim 9, characterized in that: A handle is arranged at the bottom of the penultimate step of the ladder foot section, the buttons are arranged on both sides of the handle, and the step of the first ladder frame and the penultimate step of the ladder foot section are both provided with binding belts.

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