Foldable extension ladder

Abstract

The invention discloses a foldable extension ladder convenient for extension and storage. The foldable extension ladder comprises a platform part, the step ladder part is connected to one end of the platform part in a turnover manner; the step ladder part is provided with an inner ladder and an outer ladder; a plurality of positioning holes at different positions are formed in the left side wall and the right side wall of the inner ladder in the length direction; the outer ladder is provided with a rotary telescopic positioning connection structure, and the rotary telescopic positioning connection structure can be fixedly mounted on the outer ladder and can be operably inserted into the positioning hole, so that the outer ladder can be operably positioned or slidably connected to the outside of the inner ladder, and the outer ladder is positioned and connected to different positions in the extending direction of the inner ladder.

Description

Technical Field

[0001] The present application relates to the field of ladders, and in particular to a rotary telescopic positioning connection structure and a foldable telescopic ladder. Background Art

[0002] Ladder has different meanings such as in steps, stairs, folding ladders of different sizes, rungs, extension ladders, etc. Ladders are used to reach many different heights including changing light bulbs, reaching into tall cabinets, climbing onto the roof of a house, climbing onto a truck or RV, etc.

[0003] Among them, the common heavy-duty truck ladders on the market are generally made of welded steel frames, which take up a lot of space and are not easy to fold and store. Even if a common retractable structure is used, it usually adopts a folding structure. The operator needs to manually fold the ladder at the bottom to the top for fixing, which is time-consuming and labor-intensive, and the operation is very inconvenient. In the case of heavy weight, there is also a certain operational risk. Summary of the invention

[0004] In view of the above-mentioned shortcomings, an object of the present application is to provide a foldable telescopic ladder that is convenient for ladder extension and retraction.

[0005] Another object of the present application is to provide a self-locking foldable telescopic ladder.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions: A foldable telescopic ladder, comprising: Platform part; A step ladder portion is reversibly connected to one end of the platform portion; the step ladder portion has an inner ladder and an outer ladder; the left and right side walls of the inner ladder are provided with a plurality of positioning holes at different positions in the length direction thereof; the outer ladder is provided with a rotary telescopic positioning connection structure, the rotary telescopic positioning connection structure can be fixedly mounted on the outer ladder and can be inserted into the positioning hole in an operable manner, so that the outer ladder can be operably positioned or slidably connected to the outside of the inner ladder, so that the outer ladder is positioned and connected at different positions in the extension direction of the inner ladder; The step ladder part has a flat position placed horizontally with the platform part and a use position with a predetermined angle with the platform part; the foldable telescopic ladder is provided with a self-locking plate; the self-locking plate is rotatably connected to the platform part, and the self-locking plate is also provided with a track hole; the step ladder part (inner ladder) is provided with a guide rod extending into the track hole; when the step ladder part switches between the flat position and the use position, the guide rod moves along the track hole; The track hole includes a movable long hole and a limiting slot hole; during the process of the step ladder part rotating downward from the flat position to the use position, the guide rod moves in the track hole along the movable long hole until it reaches the upper end of the movable long hole; the self-locking plate rotates downward under the action of gravity to limit the guide rod in the limiting slot hole; when the guide rod is limited in the limiting slot hole, the positions of the step ladder part and the platform part are relatively fixed; when the guide rod is located in the movable long hole, the step ladder part is allowed to rotate relative to the platform part.

[0007] As a preferred aspect, the track hole is an L-shaped hole; the limit slot hole is located at the upper end of the movable long hole; when the guide rod is located at the upper end of the movable long hole, the step ladder part is located at the use position, and when the guide rod is located at the lower end of the movable long hole, the step ladder part is located at the flat position.

[0008] As a preferred aspect, the platform portion has a connecting shaft; the self-locking plate is rotatably sleeved on the connecting shaft in a manner of rotating around the axis of the connecting shaft; When the step ladder portion is located at the use position, the center of gravity of the self-locking plate deviates from the plumb line perpendicularly passing through the axis and is located close to one side of the step ladder portion.

[0009] As a preferred aspect, an anti-slip plate is also fixedly provided at the upper end of the outer ladder; A limit stop is also fixedly disposed at the lower end of the inner ladder; when the outer ladder slides down until the anti-slip plate is stopped by the limit stop, it is at the lowest position.

[0010] A rotary telescopic positioning connection structure, the rotary telescopic positioning connection structure is applied to a telescopic ladder structure having an inner ladder and an outer ladder, the left and right side walls of the inner ladder are provided with a plurality of positioning holes at different positions in the length direction thereof; the rotary telescopic positioning connection structure can be fixedly mounted on the outer ladder and operably inserted into the positioning holes, so that the outer ladder can be operably positioned or slidably connected to the outside of the inner ladder, so that the outer ladder is positioned and connected to different positions in the extension direction of the inner ladder; Wherein, the rotary telescopic positioning connection structure comprises: A positioning pin movable in the axial direction, having a positioning position for inserting into the positioning hole and an unlocking position for moving out of the positioning hole; A positioning base that can be fixedly mounted on the outer ladder, and is provided with a positioning protrusion and an elastic member that applies an elastic force to the positioning pin to move toward the positioning position; A locking knob rotatably arranged on the positioning base; the locking knob is connected to the positioning pin; the locking knob is provided with a first positioning groove and a second positioning groove for the positioning protrusion to be embedded; the depth to which the first positioning groove can be embedded by the positioning protrusion is greater than the depth to which the second positioning groove can be embedded; the locking knob has a deep positioning position and a shallow positioning position switched by rotation, and drives the positioning pin to move axially during the rotation switching process; when the locking knob is in the deep positioning position, the positioning protrusion of the positioning base is embedded in the first positioning groove; when the locking knob is in the shallow positioning position, the positioning protrusion of the positioning base is embedded in the second positioning groove.

[0011] As a preferred aspect, the difference in depth between the positioning protrusion embedded in the first positioning groove and the second positioning groove is equal to the axial movement of the positioning pin between the positioning position and the unlocking position.

[0012] As a preferred aspect, the first positioning groove and the second positioning groove are arranged on the edge of the locking knob; the edge track of the locking knob smoothly extends from the bottom of the first positioning groove to the groove opening of the second positioning groove.

[0013] As a preferred aspect, a rising and falling transition curve is formed between the groove bottom of the first positioning groove and the groove opening of the second positioning groove, and the curvature radius of the rising and falling transition curve gradually decreases from the first positioning groove to the second positioning groove.

[0014] As a preferred aspect, the width of the first positioning groove gradually increases from the groove bottom to the groove opening; and the cross-sectional shape of the positioning protrusion matches the shape of the first positioning groove.

[0015] As a preferred aspect, the positioning base is also provided with an axis tube for the positioning pin to pass through; the end of the axis tube close to the locking knob is provided with a push step; the insertion end of the positioning pin is provided with a limit step; the elastic member includes a spring that is sleeved inside the axis tube and outside the positioning pin; the spring is compressed between the push step and the limit step.

[0016] As a preferred aspect, the rotation angle of the locking knob when switching between the deep positioning position and the shallow positioning position is 90 degrees.

[0017] As a preferred aspect, the locking knob is provided with a first positioning groove at both ends along its length direction and two opposite knob side panels are provided between the two first positioning grooves; the second positioning groove is located at the center of the edge of the knob side panel; the locking knob is also provided with a knob portion for receiving force at the top of the knob side panel.

[0018] As a preferred aspect, the center position of the knob portion passes through the connecting end of the positioning pin through a connecting pin rod, thereby fixing the positioning pin and the locking knob together.

[0019] As a preferred aspect, the locking knob has an embedded cavity between the two knob side plates; the locking knob is also provided with a slot inside the embedded cavity; when the locking knob is in the deep positioning position, one end of the shaft tube is inserted into the slot.

[0020] This application has the following beneficial effects: The foldable telescopic ladder provided by the present application adopts a rotary telescopic positioning connection structure to perform a sliding positioning connection of the inner ladder and the outer ladder to form a telescopic ladder structure. The rotary telescopic positioning connection structure can position the outer ladder step by step along the inner ladder, so that the user can form a ladder of a desired length as desired, and when storing, the ladder can be shortened to the shortest by rotating the rotary telescopic positioning connection structure, which is very convenient.

[0021] The foldable telescopic ladder provided in the present application adopts a self-locking plate to self-lock and fix the platform part and the step ladder part to each other, wherein the self-locking plate rotates downward under the action of gravity to limit the guide rod in the limiting slot hole, thereby relatively fixing the positions of the step ladder part and the platform part, which is safe, reliable and very convenient to operate.

[0022] Moreover, the rotary telescopic positioning connection structure is designed with a first and second positioning groove that matches the depth of the positioning protrusion, and the deep and shallow grooves and the positioning protrusion are fitted and embedded in the way of a rotating knob, thereby driving the axial telescopic movement of the positioning pin to achieve the limitation or release of the external ladder. In addition, the design of the deep and shallow positioning grooves can stably limit the external ladder when positioning it, and the locking knob can be weakly positioned in a shallow positioning position when releasing it. In this state, the locking knob can be turned with a little force, which is very convenient.

[0023] With reference to the following description and the accompanying drawings, the specific embodiments of the present invention are disclosed in detail, indicating the manner in which the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope thereby.

[0024] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0025] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 is a three-dimensional structural diagram of a foldable telescopic ladder in one embodiment of the present application in a use state; Figure 2 yes Figure 1 Another view of; Figure 3 yes Figure 1 Side view of Figure 4 yes Figure 1 Switch to the three-dimensional structure diagram in a flat state; Figure 5 yes Figure 4 Another view of; Figure 6 yes Figure 4 Schematic diagram of the self-locking plate state; Figure 7 yes Figure 6 The three-dimensional structure diagram of the self-locking plate; Figure 8 yes Figure 6 Schematic diagram of the position of the self-locking plate in a flat state and in a use state; Fig. 9 It is a schematic diagram of the three-dimensional structure of the rotary telescopic positioning connection structure; Fig.10 yes Fig. 9 Another view of; Fig.11 yes Fig. 9 Schematic diagram of the state in the shallow positioning position; Fig.12 yes Fig. 9 Exploded view of; Fig.13 yes Fig. 9 A cross-sectional view in a shallow positioning position; Fig.14 yes Fig. 9 A cross-sectional view in a deep positioning position; Fig.15 yes Figure 1 A schematic diagram of the installation position of the rotary telescopic positioning connection structure; Fig.16 yes Figure 1 Schematic diagram of the positioning holes.

[0028] Description of reference numerals: 10. Platform part; 20. Step ladder part; 21. Inner ladder; 22. Outer ladder; 24. Handrail; 30. Self-locking plate; 40. Rotary telescopic positioning connection structure; 210, inner ladder rod; 211, first step; 215, positioning hole; 217, right side wall of inner ladder rod; 221, outer ladder rod; 225, second step; 227, right side wall of outer ladder rod; 41. Positioning base; 411. Positioning protrusion; 412. Shaft tube; 413. Upper end of shaft tube; 418. Abutting step; 419. Limiting step; 42, locking knob; 420, embedded cavity; 421, first positioning embedded groove; 422, second positioning embedded groove; 423, lifting transition curve; 429, connecting pin; 45. Insertion end; 46. Positioning pin; 47. Connecting screw; 49. Spring. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0032] like Figures 1 to 16As shown, an embodiment of the present application provides a foldable telescopic ladder, which adopts a self-locking self-locking plate and a rotary telescopic positioning connection structure 40. The self-locking plate self-locks and fixes the platform part 10 and the step ladder part 20 to each other, wherein the self-locking plate 30 rotates downward under the action of gravity to limit the guide rod 25 in the limiting slot, and the positions of the step ladder part 20 and the platform part 10 are relatively fixed, which is safe and reliable, and the operation is very convenient.

[0033] The rotary telescopic positioning connection structure 40 is applied to a telescopic ladder structure having an inner ladder 21 and an outer ladder 22. The left and right side walls of the inner ladder 21 (the right side wall 217 of the inner ladder rod) are provided with a plurality of positioning holes 215 at different positions in the length direction thereof; the rotary telescopic positioning connection structure 40 can be fixedly installed on the outer ladder 22 and can be operably inserted into the positioning holes 215, so that the outer ladder 22 can be operably positioned or slidably connected to the outside of the inner ladder 21, so that the outer ladder 22 is positioned and connected at different positions in the extension direction of the inner ladder 21.

[0034] The rotary telescopic positioning connection structure 40 is applied to extend or shorten a step structure or a rod structure such as a ladder. In this embodiment, the rotary telescopic positioning connection structure 40 is applied to a ladder such as a truck ladder to extend or shorten the step part 20 of the ladder.

[0035] The present embodiment will be described in detail below in conjunction with the overall structure of the heavy-duty truck ladder to facilitate a better understanding of the present invention.

[0036] like Figures 1 to 5 As shown, the truck ladder includes a platform portion 10 and a step portion 20. The step portion 20 is a telescopic ladder structure. One end of the platform portion 10 is hinged to one end of the step portion. The platform portion 10 is horizontally arranged, and the step portion 20 has a flat position (such as Figure 4 , Figure 5 as shown) and a use position with a predetermined angle with the platform portion 10 (as shown Figures 1 to 3 When the step ladder is in the use position, it is placed vertically below the platform 10 as a whole and forms an angle of 100-150 degrees with the platform 10.

[0037] The platform part 10 includes parallel platform frame rods and a tabletop between the platform frame rods. The platform part 10 is generally fixed horizontally or rotatably positioned on the vehicle body, and of course, the whole can be a mobile ladder, which is placed at the target position by the user and positioned horizontally.

[0038] The step ladder part is rotatably connected to one end of the platform part 10, and can be turned up and down at one end of the platform part 10 to switch between a flat position and a use position. The step ladder part includes an inner ladder 21 and an outer ladder 22; a handrail 24 is provided on the outer ladder 22. The outer ladder 22 is operably connected to the outside of the inner ladder 21 in a sliding or positioning manner to extend or shorten the step ladder part. The outer ladder 22 and the inner ladder 21 are slidably connected by a rotary telescopic positioning connection structure 40. The upper end of the inner ladder 21 is rotatably connected to one end of the platform part 10. Specifically, the upper end of the inner ladder 21 is locked and positioned by a self-locking plate 30. When the step ladder part 20 is in the use position, the positions of the step ladder part and the platform part 10 are fixed to each other by the self-locking plate 30, forming a use state with a stable structure, which is convenient for users to use.

[0039] The left and right side walls of the inner ladder 21 are provided with a plurality of positioning holes 215 at different positions in its length direction; the rotary telescopic positioning connection structure 40 can be fixedly mounted on the outer ladder 22 and can be inserted into the positioning holes 215 in an operable manner, so that the outer ladder 22 can be operably positioned or slidably connected to the outside of the inner ladder 21, so that the outer ladder 22 is positioned and connected at different positions in the extension direction of the inner ladder 21.

[0040] It should be noted that the “up, down, left, and right” in the present invention are defined with reference to the orientation of the ladder in use.

[0041] In this embodiment, the inner ladder 21 has parallel inner ladder rods 210 and a plurality of first steps 211 connecting the two inner ladder rods 210; the plurality of first steps 211 are parallel and vertically connected between the two inner ladder rods 210. The outer ladder 22 has parallel outer ladder rods 221 and a plurality of second steps 225 connecting the two outer ladder rods 221. The plurality of second steps 225 are parallel and vertically connected to one side of the two outer ladder rods 221. The first steps 211 and the second steps 225 are parallel. The spacing between the two first steps 211 is equal to the spacing between the two second steps 225. The steps can be a rod body or a plate body. In this embodiment, the first steps 211 are a pedal structure, and the second steps 225 are a rod structure.

[0042] The two outer ladder rods 221 are provided with sliding grooves opposite to each other, and the two inner ladder rods 210 are respectively embedded in the sliding grooves of the two outer ladder rods 221. The outer ladder rod 221 is covered with the outer surface of the inner ladder rod 210 by the sliding groove, and slides along the inner ladder rod 210 by the guidance of the inner ladder rod 210. The second step 225 is fixedly connected to the outer side of the outer ladder rod 221. When the first step 211 and the second step 225 are aligned, the second step 225 is located on the outer side of the first step 211. Of course, the second step 225 can also be slightly lower than the first step 211 to facilitate the user to step on and climb.

[0043] Specifically, the self-locking plate 30 is rotatably connected to the platform portion 10, and the self-locking plate 30 is also provided with a track hole 35; the step ladder portion 20 is provided with a guide rod 25 extending into the track hole 35; when the step ladder portion 20 switches between the flat position and the use position, the guide rod 25 moves along the track hole 35. The guide rod 25 is fixedly installed on the side wall of an inner ladder rod 211. Figure 1 In the embodiment, the guide rod 25 is fixedly connected to the left side wall of the left inner ladder rod.

[0044] like Figure 6 , Figure 7 , Figure 8 As shown, one end of the platform frame rod is hinged to the upper end of the inner ladder rod 211, and a connecting shaft 15 and a guide rod 25 are vertically provided on the side walls of the respective ends. The connecting shaft 15 passes through the connecting hole 31 on the self-locking plate 30 and is limited by a limit nut, so that the self-locking plate 30 is rotatably connected to the connecting shaft 15. Similarly, the guide rod 25 passes through the track hole 35 and is limited by a limit nut.

[0045] The track hole 35 includes a movable long hole 352 and a limiting slot hole 351; during the process of the step ladder part 20 rotating downward from the flat position to the use position, the guide rod 25 moves along the movable long hole 352 in the track hole 35 until it reaches the upper end of the movable long hole 352; the self-locking plate 30 rotates downward under the action of gravity to limit the guide rod 25 in the limiting slot hole 351; when the guide rod 25 is limited in the limiting slot hole 351, the positions of the step ladder part 20 and the platform part 10 are relatively fixed; when the guide rod 25 is located in the movable long hole 352, the step ladder part 20 is allowed to rotate relative to the platform part 10.

[0046] The track hole 35 is an L-shaped hole; the limit slot hole 351 is located at the upper end of the movable long hole 352; the limit slot hole 351 is shorter than the movable long hole 352. The movable long hole 352 is a straight hole, and the guide rod 25 can move along its extension direction. The two ends (upper end and lower end) of the movable long hole 352 can correspond to the horizontal position and the use position respectively. When the guide rod 25 is located at the upper end of the movable long hole 352, the step ladder part 20 is located at the use position, and when it is located at the lower end of the movable long hole 352, the step ladder part 20 is located at the horizontal position.

[0047] The platform portion 10 has a connecting shaft 15. The self-locking plate 30 is rotatably mounted on the connecting shaft 15 in a manner of rotating around the axis of the connecting shaft 15. The connecting shaft 15 is fixed to the platform frame rod of the platform portion 10. Figures 1 to 3 As shown, the connecting shaft 15 is fixed to the left platform frame rod (the end close to the step ladder portion 20), and the guide rod 25 is fixed to the upper end of the left outer ladder rod.

[0048] When the step portion 20 is in the use position, the center of gravity S of the self-locking plate 30 deviates from the plumb line perpendicularly passing through the axis and is located on the side close to the step portion 20. In this way, the self-locking plate 30 can rotate downward by itself under the action of gravity, so that the guide rod 25 enters the limiting slot 351 and is located Figure 8 The upper and lower side walls of the limiting slot 351 respectively limit the forward and backward movement (up and down movement) of the guide rod 25, so that the guide rod 25 is limited in the limiting slot 351. In this way, the step ladder part 20 cannot continue to rotate up or down due to the limitation of the guide rod 25, and is thus fixed in position. When it is necessary to retract the step ladder part 20 to the horizontal position, the self-locking plate 30 is manually lifted around the connecting shaft 15 so that the guide rod 25 enters the moving long hole 352. At this time, the step ladder part 20 can be unlocked so that the step ladder part 20 can be flipped upward until it reaches the horizontal position and enters the horizontal position. Figure 8 Position A in .

[0049] See also Figures 9 to 16 As shown, the rotary telescopic positioning connection structure 40 is fixedly connected to the outer ladder 22. Specifically, the two rotary telescopic positioning connection structures 40 are respectively located on the left and right side walls (a left side wall and a right side wall 227) of the two outer ladder rods 221 of the outer ladder 22.

[0050] The rotary telescopic positioning connection structure 40 includes a positioning pin 46 that can be telescopic along the length direction of the second step 225, a positioning base 41, and a locking knob 42 that can be rotatably arranged on the positioning base 41. Specifically, the rotary telescopic positioning connection structure 40 includes: a positioning pin 46 that can be moved in the axial direction, having a positioning position inserted into the positioning hole 215 and an unlocking position moved out of the positioning hole 215; a positioning base 41 that can be fixedly installed on the outer ladder 22, which is provided with a positioning protrusion 411 and an elastic member that applies an elastic force to the positioning pin 46 to move toward the positioning position; and a locking knob 42 that can be rotatably arranged on the positioning base 41.

[0051] The axial direction of the positioning pin 46 is the length direction of the second step 225, and is perpendicular to the inner and outer ladder rods 221. One end of the positioning pin 46 is a connection end connected to the lock knob 42, and the other end is an insertion end 45. The positioning pin 46 can rotate with the lock knob 42. The lock knob 42 drives the positioning pin 46 to rotate around a rotation axis, and the rotation axis is parallel to the length direction of the second step 225.

[0052] The locking knob 42 is connected to the positioning pin 46; the locking knob 42 is provided with a first positioning groove 421 and a second positioning groove 422 for the positioning protrusion 411 to be embedded; the depth of the first positioning groove 421 that can be embedded by the positioning protrusion 411 is greater than the depth of the second positioning groove 422 that can be embedded. The locking knob 42 has a deep positioning position and a shallow positioning position that can be switched by rotation, and drives the positioning pin 46 to move axially during the rotation switching process. When the locking knob 42 is at the deep positioning position, the positioning protrusion 411 of the positioning base 41 is embedded in the first positioning groove 421; when the locking knob 42 is at the shallow positioning position, the positioning protrusion 411 of the positioning base 41 is embedded in the second positioning groove 422.

[0053] The difference in depth between the positioning protrusion 411 and the first positioning groove 421 and the second positioning groove 422 is equal to the axial movement of the positioning pin 46 between the positioning position and the unlocking position. The first positioning groove 421 and the second positioning groove 422 are arranged at the edge of the locking knob 42; the edge track of the locking knob 42 smoothly extends from the bottom of the first positioning groove 421 to the notch of the second positioning groove 422. The groove width (the distance between the two knob side plates) of the first positioning groove 421 gradually increases from the bottom of the groove to the notch.

[0054] In this embodiment, the positioning base 41 is fixedly connected to the outer ladder rod 221. Fig.12 As shown, the positioning base 41 is fixedly connected to the left side wall or the right side wall 227 of the outer ladder rod 221 by connecting screws 47. The side walls (a left side wall and a right side wall 227) of the two outer ladder rods 221 are also provided with through holes for the positioning pins 46 to pass through.

[0055] The positioning base 41 has positioning protrusions 411 protruding from the left and right side walls of the outer ladder rod 221, and the positioning base 41 extends along the length direction of the outer ladder rod 221. The cross-sectional shape of the positioning protrusion 411 basically matches the cross-sectional shape of the first positioning bezel 421. The cross-sectional shape of the second positioning bezel 422 basically matches the cross-sectional shape of the top portion of the positioning protrusion 411. The edge track of the lock knob 42 smoothly extends from the bottom of the first positioning bezel 421 to the notch of the second positioning bezel 422. Between the bottom of the first positioning bezel 421 and the notch of the second positioning bezel 422 is a lifting transition curve 423, and the curvature radius of the lifting transition curve 423 gradually decreases from the first positioning bezel 421 to the second positioning bezel 422.

[0056] The lock knob 42 has opposite knob side plates, and an inner cavity 420 is formed between the two knob side plates. The inner cavity 420 is formed with first positioning grooves 421 at both ends of the lock knob 42. The knob side plates are provided with second positioning grooves 422. The groove depth of the first positioning groove 421 is greater than that of the second positioning groove 422. The difference between the groove depth of the first positioning groove 421 and the groove depth of the second positioning groove 422 is approximately the telescopic distance of the positioning pin 46.

[0057] Following the above description, the lock knob 42 has a deep positioning position and a shallow positioning position that can be switched by rotation. When the lock knob 42 is in the deep positioning position, the positioning protrusion 411 of the positioning base 41 is embedded in the first positioning groove 421. When the lock knob 42 is in the shallow positioning position, the top of the positioning protrusion 411 of the positioning base 41 is embedded in the second positioning groove 422. The rotation angle of the lock knob 42 switching between the deep positioning position and the shallow positioning position is 90 degrees. When the lock knob 42 is in the shallow positioning position, the force required to disengage the position is small, and the user only needs to use appropriate force to rotate the lock knob 42, which is convenient for the user to operate.

[0058] The inner ladder rod 210 is provided with a plurality of positioning holes 215 along its length. The positioning holes 215 can be provided by the first step 211, and positioning holes 215 of different heights correspond to the first step 211 of different heights. The first step 211 has a step support rod, and the rod end of the step support rod passes through the inner ladder rod 210 and provides the positioning holes 215. The insertion end 45 of the positioning pin 46 can be inserted into the positioning hole 215, and the outer ladder 22 is positioned at the current position by the first step 211 (inner ladder rod 210).

[0059] Of course, the positioning hole 215 can also be staggered with the first step 211 and only opened on the inner ladder rod 210. At this time, the positioning pin 46 is inserted into the positioning hole 215, and the outer ladder 22 is supported and limited by the inner ladder rod 210. The present application is not limited to the illustrated embodiment.

[0060] The positioning base 41 is provided with a through hole for the positioning pin 46 to pass through. A shaft tube 412 is provided on the positioning base 41. The through hole is located in the shaft tube 412. The shaft tube 412 and the positioning base 41 are an integral structure. A top step 418 is provided at the outer end of the shaft tube 412. The elastic member includes a spring 49 located in the through hole; the spring 49 is sleeved outside the positioning pin 46. A limiting step 419 is provided at the insertion end 45 of the positioning pin 46. The spring 49 is compressed between the top step 418 and the limiting step 419, one end of the spring 49 abuts against the top step 418, and the other end abuts against the limiting step 419, thereby applying an elastic force in the insertion direction to the positioning pin 46. Relying on the elastic force of the elastic part, the locking knob 42 can be tightly attached to the positioning base 41 and stably limited to the deep positioning position and the shallow positioning position, and it is not easy to cause unexpected rotation and dislocation. Therefore, the positioning pin 46 can have a stable positioning position, which is convenient for positioning the inner ladder 21 and the outer ladder 22 at the desired telescopic position.

[0061] The upper end of the lock knob 42 is a knob portion, which is located at the top of the two knob side plates. The locating pin 46 and the lock knob 42 are fixedly connected by passing the connecting pin rod 429 through the connecting end of the locating pin 46 at the center position of the knob portion. The lock knob 42 is also provided with a slot located in the middle of the embedded cavity 420 for the upper end 413 (outer end, close to the end of the lock knob 42) of the shaft tube to be inserted and facilitate the locating protrusion 411 to be embedded in the first locating embedded groove 421 to a sufficient depth, so as to position the relative positions of the inner ladder 21 and the outer ladder 22 firmly enough.

[0062] The left and right side walls of the two inner ladder rods 210 are respectively provided with a plurality of left-right aligned positioning holes 215, and the positioning holes 215 are located on the left and right sides of the first step 211. There are corresponding positioning holes 215 on both sides of each first step 211, and the outer ladder 22 can be positioned and connected to the inner ladder 21 step by step by means of the rotary telescopic positioning connection structure 40. The rotary telescopic positioning connection structure 40 is fixedly connected to the upper end of the outer ladder 22, and the left and right rotary telescopic positioning connection structures 40 are rotated together to be located at the deep positioning position or the shallow positioning position at the same time, so as to realize the positioning or sliding of the outer ladder 22 on the inner ladder 21.

[0063] When in use, the locking knob 42 is rotated 90 degrees into a shallow positioning position (such as Fig.11 , Fig.13 As shown in the state position, after the outer frame is unlocked and limited, the outer ladder 22 can slide up and down along the inner ladder 21 to a suitable position, and then rotate 90 degrees again to re-enter the deep positioning position (as shown in the state position). Fig. 9 , Fig.14 In the state position shown), the outer ladder 22 is locked and the step ladder part 20 is structurally fixed and can be used.

[0064] In this embodiment, an anti-slip plate 27 is fixedly provided at the upper end of the outer ladder 22. The anti-slip plate 27 is parallel to the second step. The anti-slip plate 27 can be installed on the front side wall 226 (or the inner side, defined by the state when climbing the ladder, for example: the platform part 10 is located on the front side of the step part 20) of the second step 225. The anti-slip plate 27 and the second step 225 are respectively fixed to the front and rear sides of the outer ladder rod 221, and the first step 211 is located between the two. A limit stop 213 is also fixedly provided at the lower end of the inner ladder 21. When the outer ladder 22 slides down until the anti-slip plate 27 is stopped by the limit stop 213, it is at the lowest position. The limit stop 213 includes a baffle. The limit stop 213 is fixed on the inner side wall of the inner ladder rod 211 and extends forward to the stop end 217. When the anti-slip plate 27 descends, it encounters the stop end 217 and is supported and limited by the stop. The anti-drop plate 27 is located at the upper end of the outer ladder 22 and is at the same height as the uppermost second step 225. The anti-drop plate 27 cooperates with the limit stop 213 to prevent the outer ladder from slipping off and disengaging after the lock knob 42 is unlocked.

[0065] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but should be determined with reference to the appended claims and the full scope of equivalents possessed by such claims. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of the subject matter, nor should it be considered that the inventors did not consider the subject matter to be part of the disclosed inventive subject matter.

Claims

1. A foldable telescopic ladder, characterized in that: include: Platform part; A step ladder portion reversibly connected to one end of the platform portion; The step ladder part has an inner ladder and an outer ladder; The left and right side walls of the inner ladder are provided with a plurality of positioning holes at different positions in the length direction thereof; the outer ladder is provided with a rotary telescopic positioning connection structure, which can be fixedly mounted on the outer ladder and inserted into the positioning holes in an operable manner, so that the outer ladder can be operably positioned or slidably connected to the outside of the inner ladder, so that the outer ladder is positioned and connected at different positions in the extension direction of the inner ladder; The step ladder part has a flat position placed horizontally with the platform part and a use position with a predetermined angle with the platform part; the foldable telescopic ladder is provided with a self-locking plate; the self-locking plate is rotatably connected to the platform part, and the self-locking plate is also provided with a track hole; the upper end of the inner ladder is provided with a guide rod extending into the track hole; when the step ladder part is switched between the flat position and the use position, the guide rod moves along the track hole; The track hole includes a movable long hole and a limiting slot hole; during the process of the step ladder part rotating downward from the flat position to the use position, the guide rod moves in the track hole along the movable long hole until it reaches the upper end of the movable long hole; the self-locking plate rotates downward under the action of gravity to limit the guide rod in the limiting slot hole; when the guide rod is limited in the limiting slot hole, the positions of the step ladder part and the platform part are relatively fixed; when the guide rod is located in the movable long hole, the step ladder part is allowed to rotate relative to the platform part.

2. The foldable telescopic ladder according to claim 1, characterized in that: The track hole is an L-shaped hole; the limit slot hole is located at the upper end of the movable long hole; when the guide rod is located at the upper end of the movable long hole, the step ladder part is located at the use position, and when the guide rod is located at the lower end of the movable long hole, the step ladder part is located at the flat position.

3. The foldable telescopic ladder according to claim 2, characterized in that: The platform portion has a connecting shaft; the self-locking plate is rotatably sleeved on the connecting shaft in a manner of rotating around the axis of the connecting shaft; When the step ladder portion is located at the use position, the center of gravity of the self-locking plate deviates from the plumb line perpendicularly passing through the axis and is located close to one side of the step ladder portion.

4. The foldable telescopic ladder according to any one of claims 1 to 3, characterized in that: The rotary telescopic positioning connection structure comprises: A positioning pin movable in the axial direction, having a positioning position for inserting into the positioning hole and an unlocking position for moving out of the positioning hole; A positioning base that can be fixedly mounted on the outer ladder, and is provided with a positioning protrusion and an elastic member that applies an elastic force to the positioning pin to move toward the positioning position; A locking knob rotatably arranged on the positioning base; the locking knob is connected to the positioning pin; the locking knob is provided with a first positioning groove and a second positioning groove for the positioning protrusion to be embedded; the depth to which the first positioning groove can be embedded by the positioning protrusion is greater than the depth to which the second positioning groove can be embedded; the locking knob has a deep positioning position and a shallow positioning position switched by rotation, and drives the positioning pin to move axially during the rotation switching process; when the locking knob is in the deep positioning position, the positioning protrusion of the positioning base is embedded in the first positioning groove; when the locking knob is in the shallow positioning position, the positioning protrusion of the positioning base is embedded in the second positioning groove.

5. The foldable telescopic ladder according to claim 4, characterized in that: The difference in depth between the first positioning groove and the second positioning groove into which the positioning protrusion is embedded is equal to the axial movement of the positioning pin between the positioning position and the unlocking position.

6. The foldable telescopic ladder according to claim 4, characterized in that: The first positioning groove and the second positioning groove are arranged on the edge of the locking knob; the edge track of the locking knob smoothly extends from the bottom of the first positioning groove to the notch of the second positioning groove; there is a lifting transition curve between the bottom of the first positioning groove and the notch of the second positioning groove, and the curvature radius of the lifting transition curve gradually decreases from the first positioning groove to the second positioning groove; the groove width of the first positioning groove gradually increases from its bottom to its notch; the cross-sectional shape of the positioning protrusion matches the shape of the first positioning groove.

7. The foldable telescopic ladder according to claim 4, characterized in that: The positioning base is also provided with an axis tube for the positioning pin to pass through; the end of the axis tube close to the locking knob is provided with a push step; the insertion end of the positioning pin is provided with a limit step; the elastic member includes a spring sleeved inside the axis tube and outside the positioning pin; the spring is compressed between the push step and the limit step.

8. The foldable telescopic ladder according to claim 4, characterized in that: The rotation angle of the locking knob for switching between the deep positioning position and the shallow positioning position is 90 degrees.

9. The foldable telescopic ladder according to claim 7, characterized in that: The locking knob is provided with a first positioning groove at both ends along its length direction and two opposite knob side plates are provided between the two first positioning grooves; the second positioning groove is located at the center of the edge of the knob side plate; the locking knob is also provided with a knob part for receiving force at the top end of the knob side plate.

10. The foldable telescopic ladder according to claim 9, characterized in that: The center position of the knob part is connected by a connecting pin rod passing through the connecting end of the positioning pin, so that the positioning pin and the locking knob are fixedly connected; the locking knob has an embedded cavity between the two knob side plates; the locking knob is also provided with a slot inside the embedded cavity; when the locking knob is in the deep positioning position, one end of the shaft tube is inserted into the slot.

11. The foldable telescopic ladder according to claim 1, characterized in that: The upper end of the outer ladder is also provided with an anti-slip plate; A limit stopper is also fixedly disposed at the lower end of the inner ladder; when the outer ladder slides down until the anti-slip plate is stopped by the limit stopper, it is at the lowest position.

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