Stabilizing structure with connecting rods for stepladder

Abstract

A stabilizing structure with connecting rods for a stepladder, characterized in that the stabilizing structure comprises a cross tube (2) and two connecting rod structures, wherein the two connecting rod structures are articulated between two ladder bodies of the stepladder and are arranged symmetrically in the front-rear direction, wherein the connecting rod structures comprise a first connecting rod (4) and a second connecting rod (5), wherein the opposite ends of the first connecting rod (4) and the second connecting rod (5) are articulated to the two ladder bodies of the stepladder, wherein a connecting sleeve (6) is firmly mounted on the other end of the first connecting rod (4), wherein a pin (7) is slidably connected to the connecting sleeve (6), wherein one end of the pin (7) slidably penetrates the first connecting rod (4), protrudes from the connecting sleeve (6), and has an arcuate section,wherein the other end of the second connecting rod (5) is rotatably connected to the connecting sleeve (6) and the first connecting rod (4) by a spindle, wherein an insertion hole (8) is provided in the second connecting rod (5) into which the end of the pin (7) protruding from the connecting sleeve (6) can be inserted, wherein the cross tube (2) is connected between the two connecting sleeves (6) and is in communication with the two connecting sleeves (6), and wherein a drive structure is provided in the cross tube (2) and the two connecting sleeves (6), which drive structure is used to drive the simultaneous retraction of the two pins (7) into the connecting sleeves (6) and to generate springback forces on the pins (7).

Description

Technical area

[0001] The invention relates to the technical field of ladders, in particular to a stabilizing structure with connecting rods for a stepladder. State of the art

[0002] A stepladder is a device used to assist a builder when working overhead. Currently, a stepladder typically consists of two ladder sections hinged together at the top. When not in use, the two ladder sections are folded together for easier storage. When in use, the two ladder sections are unfolded, forming an angle between the two, with the lower ends of the ladder sections in contact with the floor. This allows the stepladder to remain upright during use without the need for manual support or any aids.

[0003] However, since the included angle between the two conductor bodies is not limited, if one leg of the conductor slips, it could be increased due to vibration and dangerous fluctuation of the telescopic conductor bodies could occur.

[0004] Therefore, in the prior art, two stabilizing structures arranged symmetrically in the left-right direction are typically connected between the two ladder bodies. The stabilizing structure typically consists of two connecting rods. The opposite ends of the connecting rods are hinged to the two ladder bodies, and the opposite ends of the connecting rods are hinged to each other. Examples include a Model A11 safe folding household ladder, a Model A0113-104 household ladder, a Model 33-4 insulated fiber-reinforced plastic ladder, etc.

[0005] The stabilizing structures are folded or unfolded together with the stepladder. The stabilizing structures serve both to limit the unfolded angle of the stepladder to prevent instability due to an excessively large unfolded angle, and to increase the stability of the stepladder when the worker is standing on the stepladder. Since the two connecting rods are not connected to each other when the stepladder is unfolded without a worker, the stepladder has poor stability, resulting in a risk of the stepladder tipping over if a part near the bottom of the stepladder is accidentally touched. For example, if the stepladder is unfolded without a worker, the stabilizing structures serve to limit the stability of the stepladder.If a worker unfolds the stepladder and falls down in an accident while climbing the stepladder and presses the part near the bottom of the stepladder, the stepladder would be rotated and folded at a certain angle, so that the stepladder can no longer stand stably on the floor and could tip over and even fall on the worker.

[0006] In summary, the stabilizing structure in the current technology can only play a stabilizing role when the worker is standing on the stepladder and exerting their weight on it. When no worker is standing on the stepladder, the stabilizing structure only serves to limit the unfolded angle of the stepladder without improving the stability of the stepladder.

[0007] Therefore, the invention presents a technical solution to solve the above problem that the stepladder has poor stability when no worker is standing on it. Contents of this utility model

[0008] In view of the disadvantage of the prior art, an object of the invention is to provide a stabilizing structure with connecting rods for a stepladder, in which a first connecting rod and a second connecting rod are automatically fastened upon full deployment of the stepladder, thereby locking the connecting rod structures. Even when no user is standing on the stepladder, the connecting rod structure can increase the stability of the stepladder. Furthermore, the two connecting rod structures can be unlocked simultaneously with a single operation, which has the following technical effect of enabling quick and convenient unlocking of the connecting rod structures without compromising the efficiency of assembling the stepladder.

[0009] A stabilizing structure with connecting rods for a stepladder comprises a cross tube and two connecting rod structures. The two connecting rod structures are hinged between two ladder bodies of the stepladder and arranged symmetrically in the front-to-back direction. The connecting rod structures comprise a first connecting rod and a second connecting rod. The opposite ends of the first connecting rod and the second connecting rod are hinged to the two ladder bodies of the stepladder. A connecting sleeve is fixedly mounted on the other end of the first connecting rod. A pin is slidably connected to the connecting sleeve. One end of the pin slidably penetrates the first connecting rod, protrudes from the connecting sleeve, and has an arcuate section. The other end of the second connecting rod is rotationally connected to the connecting sleeve and the first connecting rod by a spindle.The second connecting rod has an insertion hole into which the end of the pin protruding from the connecting sleeve can be inserted. The cross tube is connected between the two connecting sleeves and communicates with them. A drive structure is provided in the cross tube and the two connecting sleeves. This drive structure is used to drive the simultaneous retraction of the two pins into the connecting sleeves and generate rebound forces on the pins.

[0010] With the above technical solution, the first connecting rod and the second connecting rod in the connecting rod structure rotate with the relative rotation between the two ladder bodies of the stepladder. When the stepladder is unfolded, the connecting rod structures also unfold, and the included angle between the first and second connecting rods gradually increases until the included angle between the first connecting rod and the second connecting rod reaches 180°. During the rotation and unfolding of the connecting rod structures, the second connecting rod presses the end of the pin, which has an arcuate cross-section and protrudes from the connecting sleeve, so that under the pressure of the second connecting rod, the pin is retracted into the connecting sleeve and actuates the drive structure. The drive structure generates a rebound force on the pin.When the included angle between the first connecting rod and the second connecting rod is 180°, the pin is aligned with the insertion hole. Under the action of the springback force, the pin is returned, and the end of the pin protruding from the connecting sleeve is inserted into the insertion hole to establish the fastening between the first connecting rod and the second connecting rod. Thus, after the stepladder is unfolded, the connecting rod structures are automatically locked. When the stepladder is to be folded, the pins are simultaneously retracted into the connecting sleeve under the drive of the drive structure, thus unlocking the connecting rod structures. When the stepladder is folded, the connecting rod structures are automatically folded.After the invention is mounted on a stepladder, the first connecting rod and the second connecting rod can be automatically secured when the stepladder is fully deployed, thereby locking the connecting rod structures. Even when no user is standing on the stepladder, the connecting rod structure can increase the stability of the stepladder. Furthermore, the two connecting rod structures can be unlocked simultaneously with a single operation, resulting in quick and convenient unlocking of the connecting rod structures and not compromising the efficiency of the stepladder assembly.

[0011] According to the invention, it is further provided that a positioning plate for positioning the second connecting rod is formed in one piece on an outer side wall of the connecting sleeve.

[0012] With the above technical solution, the rotation and deployment of the first connecting rod and the second connecting rod cannot continue when the second connecting rod is brought into contact with the positioning plate. The included angle between the first connecting rod and the second connecting rod is exactly 180°, and the pin is precisely aligned with the insertion hole. The provision of the positioning plate ensures precise alignment of the pin with the insertion hole.

[0013] According to the invention, the drive structure comprises a first push button, a push rod, and two first drive assemblies located in the two connecting sleeves and arranged symmetrically in the front-to-back direction. The first drive assembly comprises a push block, a fixing sleeve, and a movable block. The fixing sleeve is fixed in the connecting sleeve. One end of the pin slidably enters the fixing sleeve, and a first spring is fixedly connected between this end and an inner lower wall of the fixing sleeve. The movable block is located in the connecting sleeve and is externally fitted onto the pin. A first bevel is provided on the movable block. The push block is located in the connecting sleeve. A first sliding groove extending in the left-right direction and a second bevel matching the first bevel are provided on the push block.The push block is movable in the left-right direction along the inner side wall of the connecting sleeve and is slidably mounted on the pin from the outside through the first sliding groove. The push rod is movable in the left-right direction along an inner side wall of the cross tube. A front end and a rear end of the push rod enter the two connecting sleeves and are firmly connected to the two push blocks. One end of the first push button is firmly connected to the push rod, and the other end of the first push button slidably protrudes from the cross tube.

[0014] With the above technical solution, the first push button is pressed when the drive structure requires the two pins to be retracted into the connecting sleeve simultaneously. The first push button moves the push rod along the inner side wall of the cross tube. The push rod moves the two push blocks simultaneously. The push block moves along the inner side wall of the connecting sleeve and along the pin through the first sliding groove. The second bevel is pressed against the first bevel. The force exerted on the first bevel can be decomposed into force components, one of which moves the first bevel toward the fastening sleeve. Under the action of this force component, the movable block displaces the pin toward the interior of the pin. Thus, the pin is pulled out from the insertion hole and returned to the connecting sleeve. At the same time, the first spring is compressed to generate a springback force.

[0015] According to the invention, it is further provided that a first auxiliary spring is firmly connected between the ends of the pin and the inner side walls of the two connecting sleeves.

[0016] With the above technical solution, the first auxiliary spring is pressed to generate a rebound force when the push rod is moved along the inner wall of the cross tube. The first auxiliary spring, in combination with the first spring, ensures that the drive structure and pins can reset after the first push button is released.

[0017] According to the invention, it is further provided that the drive structure comprises a second push button, a fastening bushing, a mounting block, and two second drive assemblies. The fastening bushing is firmly mounted from the outside on a central part of the cross tube. A first opening, which communicates with the interior of the fastening bushing, is provided in an outer side wall of the fastening bushing. A second opening, which communicates with the interior of the cross tube and corresponds to the first opening, is provided in the cross tube. The mounting block is fastened in the cross tube. In a side of the mounting block facing the second opening, two mounting grooves are provided that are arranged symmetrically in the front-rear direction. A second sliding groove is provided in each of the two mounting grooves, opposite groove walls.One end of the second push button is located outside the mounting sleeve, and the other end of the second push button slidably enters the mounting sleeve through the first opening. The two second drive assemblies correspond to the two mounting grooves and are arranged symmetrically in the front-rear direction. The second drive assembly includes a push rod, a pivot block, and a slide rod. One end of the push rod is fixedly connected to the second push button, and the other end of the push rod is pivotally connected to the pivot block. The other end of the pivot block is rotatably connected between an upper groove wall and a lower groove wall of the mounting groove by a pivot shaft and is integrally formed with two spaced-apart rotary plates. A round plate is integrally formed at each end of the two rotary plates facing away from the pivot block. One end of the slide rod slidably enters the second slide groove.A second spring is firmly connected between the groove bottoms of the second sliding grooves. The other end of the sliding rod protrudes from the second sliding groove, to which a transition rod is attached. A movable rod is attached to the other end of the transition rod. The sliding rod, the transition rod, and the movable rod are arranged concentrically and coaxially. The cross-sectional areas of the sliding rod and the movable rod are larger than those of the transition rod. The transition rod penetrates the gap between the two round plates. The opposite sides of the sliding rod and the movable rod rest against the outer side walls of the round plates. The two movable rods correspond to the two pins. One end of the movable rod facing away from the transition rod slidably protrudes from the mounting block, enters the connecting sleeve, and is firmly connected to the pin.

[0018] With the above technical solution, when the drive structure requires the two pins to be retracted into the connecting sleeve at the same time, the second push button is pressed. The second push button moves the push rod. The push rod rotates the rotary block. The rotary block rotates the rotary plate. The rotary plate rotates the round plate. The round plate pushes the slide rod. The slide rod enters the second slide groove, so that the second spring is pressed to generate a rebound force. The slide rod, under the drive of the transition rod, moves the movable rod, so that it is returned to the cross tube. Thus, the pin is pulled out from the insertion hole under the drive of the movable rod and returned to the connecting sleeve.

[0019] According to the invention, it is further provided that a second auxiliary spring is fastened between the two mounting grooves at an end of the mounting block facing the second opening and the other end of the second auxiliary spring is firmly connected to the second push button.

[0020] With the above technical solution, the second auxiliary spring is compressed to generate a rebound force when the second push button is pressed. The second auxiliary spring, combined with the second spring, ensures that the drive structure and pins can reset after the second push button is released.

[0021] According to the invention, it is further provided that the drive structure consists of two third drive assemblies arranged symmetrically in the front-rear direction. The third drive assembly comprises a mounting sleeve, a sliding block, a third sliding groove, and a pull rod. The mounting sleeve is fixed in the cross tube. One end of the pull rod slidably enters the mounting sleeve, and a third spring is fixedly connected between this end and an inner lower wall of the mounting sleeve. The other end of the pull rod protrudes from the mounting sleeve and is fixedly connected to the pin. The third sliding groove is arranged in an outer side wall of the cross tube, and the third sliding groove extends transversely to the front-rear direction and communicates with the interior of the cross tube. The sliding block slides along the third sliding groove in the front-rear direction. A lower end of the sliding block is fixedly connected to the pull rod.An upper end of the sliding block protrudes from the cross tube through the third sliding groove.

[0022] With the above technical solution, the two sliding blocks are moved toward each other when the drive structure is to retract the two pins simultaneously into the connecting sleeve. The sliding block slides along the third sliding groove. The sliding block sets the pull rod in motion toward the interior of the mounting sleeve. The pin is retracted into the connecting sleeve under the drive of the pull rod. The third spring is compressed to generate a rebound force.

[0023] According to the invention, it is further provided that a sliding plate for covering the third sliding groove is formed in one piece at the upper end of the sliding block and a vertical plate is formed in one piece at an upper end of the sliding plate.

[0024] With the above technical solution, the provision of the vertical plate facilitates the movement of the sliding plate, and the arrangement of the sliding plate allows the third sliding groove to be covered. This prevents the penetration of dust, rainwater, and the like from the outside into the cross pipe.

[0025] Compared with the prior art, the present invention has the following advantageous effects: A stabilizing structure with connecting rods for a stepladder is provided. After the invention is mounted on a stepladder, when the stepladder is fully deployed, the first connecting rod and the second connecting rod can be automatically fastened, thereby locking the connecting rod structures. Even when no user is standing on the stepladder, the connecting rod structure can increase the stability of the stepladder. Furthermore, the two connecting rod structures can be unlocked simultaneously with a single operation, resulting in quick and convenient unlocking of the connecting rod structures and not compromising the efficiency of the stepladder assembly. Short description of the characters Fig. 1 is a schematic structural view of a stabilizing structure with connecting rods according to Embodiment 1 after assembly on a stepladder; Fig. 2 is a schematic structural view of the stabilizing structure with connecting rods according to Embodiment 1; Fig. 3 is a partial section of the stabilizing structure with connecting rods according to embodiment I in a plan view; Fig. 4 is an enlarged view at location A of Fig. 3; Fig. 5 is a schematic partial structural view of a first connecting rod, a second connecting rod, a pin, a push rod, and a first drive assembly according to Embodiment 1; Fig. 6 is a schematic structural view according to Embodiment II; Fig. 7 is a partial section according to embodiment II in a plan view; Fig. 8 is an enlarged view at location B of Fig. 7; Fig. 9 is an enlarged view at location C of Fig. 7; Fig. 10 is a schematic partial structural view of a second push button and a second drive assembly according to Embodiment II; Fig. 11 is a schematic structural view according to Embodiment III; Fig. 12 is a partial section according to Embodiment III in a side view; Fig. 13 is an enlarged view at location D of Fig. 12; and Fig. 14 is an enlarged view at location E of Fig. 12. List of reference symbols:

[0026] 1. Stepladder; 2. Cross tube; 3. Mounting plate; 4. First connecting rod; 5. Second connecting rod; 6. Connecting sleeve; 7. Pin; 8. Insert hole; 9. First push button; 10. Push rod; 11. Push block; 12. Fixing sleeve; 13. Movable block; 14. First spring; 15. First bevel; 16. First sliding groove; 17. Second bevel; 18. First auxiliary spring; 19. Positioning plate; 20. Second push button; 21. Fixing sleeve; 22. Mounting block; 23. First opening; 24. Second opening; 25. Mounting groove; 26. Second sliding groove; 27. Push rod; 28. Pivot block; 29. Sliding rod; 30. Pivot plate; 31. Round plate; 32. Second spring; 33. Transition rod; 34. Movable rod; 35. second auxiliary spring; 36. mounting sleeve; 37. sliding block; 38. third sliding groove; 39. tie rod; 40. third spring; 41. sliding plate; 42. vertical plate. Specific embodiments

[0027] The technical solutions according to the invention are described clearly and comprehensively below with reference to the drawings in the exemplary embodiment of the invention. Naturally, the described exemplary embodiment does not represent all of the exemplary embodiments of the invention, but only a portion. Based on the exemplary embodiment in the present invention, other exemplary embodiments that can be obtained by a person skilled in the art without inventive step are intended to fall within the scope of the invention. Example I:

[0028] As in Fig. 1 to Fig. 5, a stabilizing structure with connecting rods for a stepladder comprises a cross tube 2 and two connecting rod structures. The two connecting rod structures are hinged between two ladder bodies of the stepladder and arranged symmetrically in the front-rear direction. The connecting rod structures comprise a first connecting rod 4 and a second connecting rod 5. The opposite ends of the first connecting rod 4 and the second connecting rod 5 are hinged to the two ladder bodies of the stepladder. A connecting sleeve 6 is fixedly fitted on the other end of the first connecting rod 4. In the connecting sleeve 6, a pin 7 is slidably connected thereto. One end of the pin 7 slidably penetrates the first connecting rod 4, protrudes from the connecting sleeve 6, and has an arcuate section.The other end of the second connecting rod 5 is rotatably connected to the connecting sleeve 6 and the first connecting rod 4 by a spindle. An insertion hole 8 is provided in the second connecting rod 5, into which the end of the pin 7 protruding from the connecting sleeve 6 can be inserted. The cross tube 2 is connected between the two connecting sleeves 6 and communicates with the two connecting sleeves 6. A drive structure is provided in the cross tube 2 and the two connecting sleeves 6, which drive structure is used to drive the simultaneous retraction of the two pins 7 into the connecting sleeves 6 and generate rebound forces on the pins 7.

[0029] The drive structure includes a first push button 9, a push rod 10, and two first drive assemblies. The two first drive assemblies are located in the two connecting sleeves 6 and are arranged symmetrically in the front-rear direction. The first drive assembly includes a push block 11, a fixing sleeve 12, and a movable block 13. The fixing sleeve 12 is fixed in the connecting sleeve 6. One end of the pin 7 slidably enters the fixing sleeve 12, and a first spring 14 is fixedly connected between this end and an inner bottom wall of the fixing sleeve 12. The movable block 13 is located in the connecting sleeve 6 and is externally fitted onto the pin 7. A first bevel 15 is provided on the movable block 13. The push block 11 is located in the connecting sleeve 6.The push block 11 is provided with a first sliding groove 16 extending in the left-right direction and a second slope 17 matching the first slope 15. The push block 11 is movable in the left-right direction along the inner side wall of the connecting sleeve 6 and is slidably fitted onto the pin 7 from the outside through the first sliding groove 16. The push rod 10 moves in the left-right direction along an inner side wall of the cross tube 2. A front end and a rear end of the push rod 10 enter the two connecting sleeves 6 and are fixedly connected to the two push blocks 11. One end of the first push button 9 is fixedly connected to the push rod 10, and the other end of the first push button 9 slidably projects from the cross tube 2. A first auxiliary spring 18 is firmly connected between the ends of the pin 10 and the inner side walls of the two connecting sleeves 6.

[0030] Additionally, a positioning plate 19 for positioning the second connecting rod 5 is integrally formed on an outer side wall of the connecting sleeve 6. The rotation and unfolding of the first connecting rod 4 and the second connecting rod 5 cannot continue when the second connecting rod 5 is brought into contact with the positioning plate 19. At this time, the included angle between the first connecting rod 4 and the second connecting rod 5 is exactly 180°, and the pin 7 is precisely aligned with the insertion hole 8. The provision of the positioning plate 19 ensures precise alignment of the pin 7 with the insertion hole 8.

[0031] It should be noted that in this embodiment, by directly linking the first connecting rod 4 and the second connecting rod 5 to a step or ladder tube of the stepladder, or to a plastic part between adjacent ladder tubes, the first connecting rod 4 and the second connecting rod 5 can be linked to the ladder bodies of the stepladder. In addition, two mounting plates 3 may also be provided. Each of the mounting plates 3 is linked between a left end and a right end of one of the connecting rod structures. Then, the mounting plate 3 is attached to the step of the stepladder by screws. The operation is as follows:

[0032] The first connecting rod 4 and the second connecting rod 5 in the connecting rod structures rotate with the relative rotation between the two ladder bodies of the stepladder 1.

[0033] When the stepladder 1 is to be folded, the first push button 9 is first pressed. The first push button 9 sets the push rod 10 in motion along the inner side wall of the cross tube 2. The first auxiliary spring 18 is pressed to generate a rebound force. The push rod 10 sets the two push blocks 11 in motion simultaneously.

[0034] The push block 11 is moved along the inner side wall of the connecting sleeve 6 and through the first sliding groove 16 along the pin 7. The second bevel 17 is pressed against the first bevel 15. The force exerted on the first bevel 15 can be decomposed into force components, one of which moves the first bevel toward the fastening sleeve 12. Under the action of this force component, the movable block 13 displaces the pin 7 toward the interior of the pin 12. Thus, the pin 7 is pulled out from the insertion hole 8 and returned to the connecting sleeve 6. At the same time, the first spring 14 is compressed to generate a spring-back force. The connecting rod structures are thereby unlocked and automatically folded when the stepladder 1 is folded.After the first push button 9 is released, the interaction of the first auxiliary spring 18 and the first spring 14 ensures that the drive structure and the pins 7 can be reset.

[0035] When the stepladder 1 is unfolded, the connecting rod structures are also unfolded, and the included angle between the first connecting rod 4 and the second connecting rod 5 gradually increases until the included angle between the first connecting rod 4 and the second connecting rod 5 reaches 180°. During the rotation and unfolding of the connecting rod structures, the second connecting rod 5 presses the end of the pin 7, which has an arcuate cross-section and protrudes from the connecting sleeve 6, so that under the pressure of the second connecting rod 5, the pin 7 is retracted into the connecting sleeve 6, and a rebound force is generated by the first spring 14. When the included angle between the first connecting rod 4 and the second connecting rod 5 is 180°, the pin 7 is aligned with the insertion hole 8.Under the action of the recoil force of the first spring 14, the pin 7 is returned, and the end of the pin 7 protruding from the connecting sleeve 6 is inserted into the insertion hole 8 to complete the fastening between the first connecting rod 4 and the second connecting rod 5. Thus, the connecting rod structures are automatically locked after the stepladder 1 is deployed.

[0036] After the invention is mounted on a stepladder 1, upon full deployment of the stepladder 1, the first connecting rod 4 and the second connecting rod 5 can be automatically secured, thereby locking the connecting rod structures. Even when no user is standing on the stepladder 1, the connecting rod structure can increase the stability of the stepladder 1. Furthermore, the two connecting rod structures can be unlocked simultaneously with one operation, resulting in quick and convenient unlocking of the connecting rod structures and not compromising the efficiency of assembling the stepladder 1. Example II:

[0037] This embodiment differs from embodiment I in that the drive structure no longer includes the first push button 9, the push rod 10 and the two first drive assemblies. As in Fig. 6 to Fig. 10, the drive structure instead comprises a second push button 20, a fastening bushing 21, a mounting block 22, and two second drive assemblies. The fastening bushing 21 is fixedly mounted from the outside on a central part of the cross tube 2. A first opening 23 is provided in an outer side wall of the fastening bushing 21, which communicates with the interior of the fastening bushing. A second opening 24 is provided in the cross tube 2, which communicates with the interior of the cross tube and corresponds to the first opening 23. The mounting block 22 is fastened in the cross tube 2. In a side of the mounting block 22 facing the second opening 24, two mounting grooves 25 are provided, arranged symmetrically in the front-rear direction. A second sliding groove 26 is provided in each of the opposite groove walls of the two mounting grooves 25. One end of the second push button 20 is located outside the fastening bushing 21.The other end of the second push button 20 slidably enters the mounting bushing 21 through the first opening 23. The two second drive assemblies correspond to the two mounting grooves 25 and are arranged symmetrically in the front-rear direction. The second drive assembly includes a push rod 27, a pivot block 28, and a slide rod 29. One end of the push rod 27 is fixedly connected to the second push button 20. The other end of the push rod 27 is pivotally connected to the pivot block 28. The other end of the pivot block 28 is pivotally connected by a pivot shaft between an upper groove wall and a lower groove wall of the mounting groove 25 and is integrally formed with two spaced-apart rotary plates 30. A circular plate 31 is integrally formed at each end of the two rotary plates 30 facing away from the pivot block 28. One end of the slide rod 29 slidably enters the second slide groove 26.A second spring 32 is firmly connected between the groove bottoms of the second sliding grooves 26. The other end of the sliding rod 29 protrudes from the second sliding groove 26, to which a transition rod 33 is attached. A movable rod 34 is attached to the other end of the transition rod 33. The sliding rod 29, the transition rod 33, and the movable rod 34 are arranged concentrically and coaxially. The cross-sectional areas of the sliding rod 29 and the movable rod 34 are larger than those of the transition rod 33. The transition rod 33 snugly penetrates the gap between the two round plates 31. The opposite sides of the sliding rod 29 and the movable rod 34 rest against the outer side walls of the round plates 31. The two movable rods 34 correspond to the two pins 7.An end of the movable rod 34 facing away from the transition rod 33 slidably protrudes from the mounting block 22, enters the connecting sleeve 6, and is fixedly connected to the pin 7. At an end of the mounting block 22 facing the second opening 24, a second auxiliary spring 35 is attached between the two mounting grooves 25. The other end of the second auxiliary spring 35 is fixedly connected to the second push button 20.

[0038] When the stepladder 1 is to be folded, the second push button 20 is pressed. The second auxiliary spring 35 is pressed to generate a rebound force. The second push button 20 moves the push rod 27. The push rod 27 rotates the rotary block 28. The rotary block 28 rotates the rotary plate 30. The rotary plate 30 rotates the round plate 31. The round plate 31 pushes the slide rod 29. The slide rod 29 enters the second slide groove 26, so that the second spring 32 is pressed to generate a rebound force. The slide rod 29, under the drive of the transition rod 33, moves the movable rod 34 so that it is returned to the cross tube 2. Thus, the pin 7 is pulled out from the insertion hole 8 under the drive of the movable rod 34 and returned to the connecting sleeve 6.The connecting rod structures are thereby unlocked and automatically folded when the stepladder 1 is folded. After the second push button 20 is released, the interaction of the second auxiliary spring 35 and the second spring 32 ensures that the drive structure and the pins 7 can be reset.

[0039] When the stepladder 1 is unfolded, the connecting rod structures are also unfolded, and the included angle between the first connecting rod 4 and the second connecting rod 5 gradually increases until the included angle between the first connecting rod 4 and the second connecting rod 5 reaches 180°. During the rotation and unfolding of the connecting rod structures, the second connecting rod 5 presses the end of the pin 7, which has an arcuate cross-section and protrudes from the connecting sleeve 6, so that under the pressure of the second connecting rod 5, the pin 7 is retracted into the connecting sleeve 6, and the movable rod 34 is driven by the pin 7 to be retracted into the cross tube 2.The movable rod 34 displaces the sliding rod 29 through the transition rod 33, causing it to enter the second sliding groove 26, and the second spring 32 is pressed to generate a rebound force. When the included angle between the first connecting rod 4 and the second connecting rod 5 is 180°, the pin 7 is aligned with the insertion hole 8. Under the action of the rebound force of the second spring 32, the pin 7 and the drive structure are returned, and the end of the pin 7 protruding from the connecting sleeve 6 is inserted into the insertion hole 8 to complete the fastening between the first connecting rod 4 and the second connecting rod 5. Thus, the connecting rod structures are automatically locked after the stepladder 1 is deployed. Example III:

[0040] This embodiment differs from embodiment I in that the drive structure no longer includes the first push button 9, the push rod 10 and the two first drive assemblies. As in Fig. 11 to Fig.14, the drive structure consists of two third drive assemblies arranged symmetrically in the front-rear direction. The third drive assembly includes a mounting sleeve 36, a sliding block 37, a third sliding groove 38, and a pull rod 39. The mounting sleeve 36 is fixed in the cross tube 2. One end of the pull rod 39 slidably enters the mounting sleeve 36, and a third spring 40 is fixedly connected between this end and an inner lower wall of the mounting sleeve 36. The other end of the pull rod 39 protrudes from the mounting sleeve 36 and is fixedly connected to the pin 7. The third sliding groove 38 is arranged in an outer side wall of the cross tube 2. The third sliding groove 38 extends transversely to the front-rear direction and communicates with the interior of the cross tube 2. The sliding block 37 slides along the third sliding groove 38 in the front-rear direction. A lower end of the sliding block 37 is firmly connected to the pull rod 39.An upper end of the sliding block 37 protrudes from the cross tube 2 through the third sliding groove 38 and is integrally formed with a sliding plate 41 for covering the third sliding groove 38. A vertical plate 42 is integrally formed at the upper end of the sliding plate 41.

[0041] When the stepladder 1 is to be folded, the user kneads the two vertical plates 42 so that the two vertical plates 42 are moved towards each other. In this way, the two sliding blocks 37 are moved towards each other by means of the sliding plate 41. The sliding block 37 slides along the third sliding groove 38. The sliding block 37 sets the pull rod 39 in motion toward the interior of the mounting sleeve 36. The pin 7 is returned into the connecting sleeve 6 under the drive of the pull rod 39. The third spring 40 is pressed to generate a rebound force. The connecting rod structures are thereby unlocked and automatically folded when the stepladder 1 is folded. After the vertical plates 42 are released, the drive structure and the pins 7 can be returned under the rebound force of the third spring 40.

[0042] When the stepladder 1 is unfolded, the connecting rod structures are also unfolded, and the included angle between the first connecting rod 4 and the second connecting rod 5 gradually increases until the included angle between the first connecting rod 4 and the second connecting rod 5 reaches 180°. During the rotation and unfolding of the connecting rod structures, the second connecting rod 5 presses the end of the pin 7, which has an arcuate cross-section and protrudes from the connecting sleeve 6, so that under the pressure of the second connecting rod 5, the pin 7 is retracted into the connecting sleeve 6, and the tension rod 39 is set in motion by the pin 7 toward the interior of the mounting sleeve 36. The third spring 40 is pressed to generate a rebound force.When the included angle between the first connecting rod 4 and the second connecting rod 5 is 180°, the pin 7 is aligned with the insertion hole 8. Under the action of the rebound force of the third spring 40, the pin 7 and the drive structure are returned, and the end of the pin 7 protruding from the connecting sleeve 6 is inserted into the insertion hole 8 to complete the fastening between the first connecting rod 4 and the second connecting rod 5. Thus, the connecting rod structures are automatically locked after the stepladder 1 is deployed.

[0043] It should be noted that the direction or positioning designated by the terms "top", "bottom", "inside", "outside", "top / bottom", etc., is used in relation to the direction or positioning shown in the respective figure, solely to describe the application and, where appropriate, to simplify the description. These terms do not implicitly or explicitly suggest the positioning, design, or operation of the device or element in question in a predetermined position, and therefore do not constitute a limitation of the application. Furthermore, the terms "first" and "second" are used solely for descriptive purposes, without implicitly or explicitly indicating relative importance.

[0044] When describing the invention, it should also be noted that, unless otherwise stated, the terms "attach", "provide", "attach", "connect", etc. should be understood in a broad sense when explaining the present invention. For example, "connect" can refer to a fixed connection, a detachable connection, or a one-piece connection. It can be either a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection via a medium, and can also be a connection between the insides of two elements. A person skilled in the art can understand the specific meaning of the above terms in the invention depending on the context.

[0045] It should be clear to those skilled in the art that the invention is not intended to be limited to the details of the embodiments described above by way of example. The invention may also be embodied in other specific forms without departing from the essence and spirit of the invention. Therefore, the embodiments should be considered as exemplary, but not restrictive. The scope of the invention should not be defined by the above description, but by the appended claims, and therefore all changes which have the same meanings and scopes as equivalent elements in the claims are intended to be included in the invention. No reference numeral should be construed as limiting the claims concerned.

[0046] It should be further understood that, although the description follows the embodiments for clarity, an embodiment may include more than one independent technical solution. It should be clear to those skilled in the art that the description should be considered as a whole, and that the technical solutions in the embodiments may, through appropriate combinations, represent other embodiments understandable to those skilled in the art.

Claims

[1] Stabilizing structure with connecting rods for a stepladder, characterized bythat the stabilizing structure comprises a cross tube (2) and two connecting rod structures, wherein the two connecting rod structures are articulated between two ladder bodies of the stepladder and are arranged symmetrically in the front-rear direction, wherein the connecting rod structures comprise a first connecting rod (4) and a second connecting rod (5), wherein the mutually opposite ends of the first connecting rod (4) and the second connecting rod (5) are articulated to the two ladder bodies of the stepladder, wherein a connecting sleeve (6) is firmly mounted on the other end of the first connecting rod (4), wherein a pin (7) is slidably connected in the connecting sleeve (6), wherein one end of the pin (7) slidably penetrates the first connecting rod (4), protrudes from the connecting sleeve (6) and has an arcuate section,wherein the other end of the second connecting rod (5) is rotatably connected to the connecting sleeve (6) and the first connecting rod (4) by a spindle, wherein an insertion hole (8) is provided in the second connecting rod (5) into which the end of the pin (7) protruding from the connecting sleeve (6) can be inserted, wherein the cross tube (2) is connected between the two connecting sleeves (6) and is in communication with the two connecting sleeves (6), and wherein a drive structure is provided in the cross tube (2) and the two connecting sleeves (6), which drive structure is used to drive the simultaneous retraction of the two pins (7) into the connecting sleeves (6) and to generate springback forces on the pins (7). [2] Stabilising structure with connecting rods for a stepladder according to claim 1, characterized bythat a positioning plate (19) for positioning the second connecting rod (5) is formed in one piece on an outer side wall of the connecting sleeve (6). [3] Stabilising structure with connecting rods for a stepladder according to claim 2, characterized byin that the drive structure comprises a first push button (9), a push rod (10) and two first drive assemblies located in the two connecting sleeves (6) and arranged symmetrically in the front-rear direction, wherein the first drive assembly comprises a push block (11), a fastening sleeve (12) and a movable block (13), wherein the fastening sleeve (12) is fastened in the connecting sleeve (6), wherein one end of the pin (7) slides into the fastening sleeve (12) and a first spring (14) is firmly connected between this end and an inner lower wall of the fastening sleeve (12), wherein the movable block (13) is located in the connecting sleeve (6) and is placed externally on the pin (7), wherein a first bevel (15) is provided on the movable block (13), wherein the push block (11) is located in the connecting sleeve (6), wherein a first sliding groove (16),which extends in the left-right direction, and a second slope (17) which matches the first slope (15) are provided, wherein the push block (11) is movable along the inner side wall of the connecting sleeve (6) in the left-right direction and is slidably mounted on the pin (7) from the outside through the first sliding groove (16), wherein the push rod (10) is movable along an inner side wall of the cross tube (2) in the left-right direction, wherein a front end and a rear end of the push rod (10) enter the two connecting sleeves (6) and are fixedly connected to the two push blocks (11), and wherein one end of the first push button (9) is fixedly connected to the push rod (10) and the other end of the first push button (9) slidably protrudes from the cross tube (2). [4] Stabilising structure with connecting rods for a stepladder according to claim 3, characterized bythat a first auxiliary spring (18) is firmly connected between the ends of the pin (10) and the inner side walls of the two connecting sleeves (6). [5] Stabilising structure with connecting rods for a stepladder according to claim 2, characterized bythat the drive structure comprises a second push button (20), a fastening bushing (21), a mounting block (22), and two second drive assemblies, wherein the fastening bushing (21) is firmly mounted from the outside on a central part of the cross tube (2), wherein a first opening (23) is provided in an outer side wall of the fastening bushing (21), which is in communication with the interior of the fastening bushing, wherein a second opening (24) is provided in the cross tube (2), which is in communication with the interior of the cross tube and corresponds to the first opening (23), wherein the mounting block (22) is fastened in the cross tube (2), wherein in a side of the mounting block (22) facing the second opening (24), two mounting grooves (25) are provided symmetrically arranged in the front-rear direction, wherein a second sliding groove (26) is provided in each of the opposite groove walls of the two mounting grooves (25),wherein one end of the second push button (20) is located outside the mounting bushing (21) and the other end of the second push button (20) slidably enters the mounting bushing (21) through the first opening (23), wherein the two second drive assemblies correspond to the two mounting grooves (25) and are arranged symmetrically in the front-rear direction, wherein the second drive assembly comprises a push rod (27), a rotary block (28), and a slide rod (29), wherein one end of the push rod (27) is fixedly connected to the second push button (20) and the other end of the push rod (27) is hinged to the rotary block (28), wherein the other end of the rotary block (28) is rotatably connected by a rotary shaft between an upper groove wall and a lower groove wall of the mounting groove (25) and is formed integrally with two spaced-apart rotary plates (30),wherein a round plate (31) is formed in one piece at each of the ends of the two rotary plates (30) facing away from the rotary block (28), wherein one end of the sliding rod (29) slides into the second sliding groove (26), wherein a second spring (32) is firmly connected between the groove bottoms of the second sliding grooves (26), wherein the other end of the sliding rod (29) protrudes from the second sliding groove (26), to which a transition rod (33) is fastened, wherein a movable rod (34) is fastened to the other end of the transition rod (33), wherein the sliding rod (29), the transition rod (33), and the movable rod (34) are arranged concentrically and coaxially, wherein the cross-sectional areas of the sliding rod (29) and the movable rod (34) are larger than those of the transition rod (33), wherein the transition rod (33) snugly penetrates the gap between the two round plates (31),wherein the opposite sides of the sliding rod (29) and the movable rod (34) abut the outer side walls of the round plates (31), wherein the two movable rods (34) correspond to the two pins (7), and wherein an end of the movable rod (34) facing away from the transition rod (33) projects slidably from the mounting block (22), enters the connecting sleeve (6) and is firmly connected to the pin (7). [6] Stabilising structure with connecting rods for a stepladder according to claim 5, characterized by that at one end of the mounting block (22) facing the second opening (24) a second auxiliary spring (35) is fastened between the two mounting grooves (25) and the other end of the second auxiliary spring (35) is fixedly connected to the second push button (20). [7] Stabilising structure with connecting rods for a stepladder according to claim 2, characterized bythat the drive structure consists of two third drive assemblies arranged symmetrically in the front-rear direction, wherein the third drive assembly comprises a mounting sleeve (36), a sliding block (37), a third sliding groove (38) and a pull rod (39), wherein the mounting sleeve (36) is fastened in the cross tube (2), wherein one end of the pull rod (39) slidably enters the mounting sleeve (36) and a third spring (40) is fixedly connected between this end and an inner lower wall of the mounting sleeve (36), wherein the other end of the pull rod (39) protrudes from the mounting sleeve (36) and is fixedly connected to the pin (7), wherein the third sliding groove (38) is arranged in an outer side wall of the cross tube (2) and the third sliding groove (38) extends transversely to the front-rear direction and is in communication with the interior of the cross tube (2), wherein the sliding block (37) is arranged along the third sliding groove (38) slides in the front-to-back direction,wherein a lower end of the sliding block (37) is fixedly connected to the pull rod (39), and wherein an upper end of the sliding block (37) protrudes from the cross tube (2) through the third sliding groove (38). [8] Stabilising structure with connecting rods for a stepladder according to claim 7, characterized by that a sliding plate (41) for covering the third sliding groove (38) is formed integrally at the upper end of the sliding block (37) and a vertical plate (42) is formed integrally at an upper end of the sliding plate (41).

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