Driving device of extensible ladder

Abstract

The present invention is characterized by comprising: an outer support unit in which a plurality of first foothold frames are provided at a predetermined interval from each other; an inner support unit which is provided inside the outer support unit and in which a plurality of second foothold frames are provided at a predetermined interval from each other; a rack gear provided on the outer surface of the inner support unit in the longitudinal direction of the inner support unit; a pinion gear connected to the rack gear and rotatably provided on the inner surface of the outer support unit; a power transmission unit which transmits rotary power to the pinion and is connected to a rotary tool; and an overload protection unit provided in the power transmission unit and preventing the power transmission unit from being damaged when an overload occurs in the process of lifting the inner support unit.

Description

Drive mechanism of a telescopic ladder

[0001] The present invention relates to a driving device for a telescopic ladder configured to enable a user to easily adjust the overall height of the ladder using a power source such as an electric tool or a battery.

[0002] In general, a ladder is a device that allows people to use their feet to climb up or down high or low places, and can be divided into work ladders and traffic ladders.

[0003] Conventional ladders can be divided into the 'H'-type ladder shown in Fig. 1 and the 'A'-type ladder shown in Fig. 2.

[0004] The 'H'-shaped ladder illustrated in Fig. 1 may be configured to include a pair of vertical braces (10) spaced apart from each other at a certain distance, and a plurality of horizontal steps (20) spaced apart from each other at a certain distance vertically between the pair of vertical braces (10).

[0005] The 'A'-shaped ladder illustrated in FIG. 2 may be configured to include a pair of front braces (30) spaced apart from each other at a predetermined interval, and a rear brace (30') that is rotatably connected to the front braces (30) and is positioned at a predetermined angle of inclination with the front braces (30).

[0006] In addition, the 'A' type ladder may further include an upper brace (40) that is inserted into the interior of the front brace (30) and the rear brace (30') and can be pulled out upward from the interior of the front brace (30) and the rear brace (30').

[0007] The conventional 'A' type ladder has a configuration in which a fixed handle (80) for fixing the height of the upper brace (40) when it is pulled out is provided on the front brace (30) and the rear brace (30').

[0008] Accordingly, the user can fix the height of the ladder by inserting the fixing handle (80) into the fixing hole (70) formed in the upper brace (40) via the front brace (30) or the rear brace (30').

[0009] In addition, the conventional 'A' type ladder has a structure that stops the rotation of the hinge (50) by using a fixed handle (60) provided at the top of the upper brace (40) as a way to fix the angle between the front brace (30) and the rear brace (30').

[0010] Accordingly, when performing high-altitude work, the user must press the fixed handle (60) to widen the gap between the front brace (30) and the rear brace (30') at a certain angle, and then lift the upper brace (40) from the front brace (30) and the rear brace (30'). Then, when the upper brace (40) is raised to the height desired by the user, the user presses the fixed handle (60) to stop the rotation of the hinge (50), and then uses the fixed handle (80) to fix the height of the upper brace (40).

[0011] Since the above series of processes must be performed every time the height of the upper support (40) is changed, there is a problem of reducing work efficiency, and since the user must repeatedly perform the action of climbing up and down the ladder every time the height of the upper support (40) is changed, there is also a problem of causing safety accidents.

[0012] In addition, the conventional 'A' type ladder has the problem of being difficult for women or the elderly to use because the process of adjusting the height of the upper support (40) is difficult and cumbersome.

[0013] Accordingly, the applicant of the present invention has developed the present invention to solve the above-mentioned problems, and related prior art documents include "Automatic ladder with adjustable length using an electric driver" of Korean Patent No. 10-1767014 and "Ladder with adjustable tray height" of Korean Patent No. 10-2099306.

[0014] The present invention is intended to solve the above-mentioned problems, and the purpose of the present invention is to provide a driving device for a telescopic ladder configured to enable a worker to easily and conveniently raise and lower an inner support portion on an outer support portion constituting the ladder using a power source such as an electric tool or a battery, thereby easily adjusting the overall height of the ladder.

[0015] A telescopic ladder may include an outer support portion having a plurality of first step frames provided at a predetermined interval from each other; and an inner support portion provided inside the outer support portion and having a plurality of second step frames provided at a predetermined interval from each other; a rack gear provided on an outer surface of the inner support portion along a longitudinal direction of the inner support portion; a pinion connected to the rack gear and rotatably provided on the inner surface of the outer support portion; and a power transmission portion that transmits rotational power to the pinion and is connected to a rotating tool.

[0016] In addition, the power transmission unit may include a first shaft that is arranged on one outer surface of the outer support and rotates by receiving power from the rotating tool; a worm provided on the first shaft; a first gear that is connected to a worm wheel gear that meshes with the worm; and a second shaft that rotates by receiving rotational force generated from the first gear and is arranged parallel to the first foot plate frame or the second foot plate frame.

[0017] Additionally, the first shaft may be arranged in a direction intersecting the first foothold frame or the second foothold frame.

[0018] In addition, the second shaft may be provided inside the first foothold frame, which is positioned at the uppermost end of the outer support portion among the plurality of first foothold frames, and may be positioned along the longitudinal direction of the first foothold frame.

[0019] In addition, a second gear connected to the first gear may be provided at one longitudinal end of the second shaft, and a third gear may be provided at the other longitudinal end of the second shaft to transmit rotational power to the pinion rotatably provided on the other inner surface of the outer support portion.

[0020] In addition, the power transmission unit may include an overload protection unit that prevents the power transmission unit from being damaged when an overload occurs during the process of the inner support unit being raised or lowered.

[0021] In addition, the overload protection unit may include a body rotatably provided on the first shaft and connected to the worm; a ball that contacts a stepped surface formed on a portion of the outer circumference of the first shaft through a screw hole formed in the body; an elastic member inserted into the screw hole, one longitudinal end of which contacts the ball; and an adjusting screw that presses the other longitudinal end of the elastic member and is fastened to the screw hole.

[0022] In addition, if an overload occurs during the process of raising and lowering the inner support, the overload protection unit and the worm are in a stopped state, and the first shaft can rotate idly.

[0023] In addition, it may further include a fine adjustment member rotatably connected to the first shaft and connected to the body.

[0024] Additionally, the power transmission unit may be connected to an output shaft of a drive motor connected to a battery.

[0025] In addition, the teeth formed by the worm have different heights, and are manufactured in a form in which the height gradually decreases from the teeth arranged at the longitudinal ends of the worm toward the teeth arranged in the middle, so that the worm can have the shape of a drum.

[0026] The drive device of the flexible ladder according to the present invention provides a structure that allows a worker to easily raise and lower an inner support part on an outer support part using an electric tool or a motor, thereby enabling the worker to perform high-altitude work safely and comfortably.

[0027] In addition, the drive device of the telescopic ladder according to the present invention has a large reduction ratio corresponding to the maximum rotation speed of the rotating tool due to the characteristics of the worm gear, so that the inner support part can be raised and lowered while amplifying the force on the output shaft of the worm wheel gear by the amount of reduction, and further, even if a load is applied to the inner support part, the inner support part can be prevented from moving downward unintentionally due to the reduction brake function of the worm and worm wheel gear.

[0028] In addition, since the drive device of the flexible ladder according to the present invention is provided with a fixing lever that stops the raising and lowering motion of the inner support part on the outer support part, the inner support part that is raised and lowered on the outer support part can be firmly fixed at a height desired by the user, thereby preventing the phenomenon of unintentional movement due to external force.

[0029] In addition, the drive device of the flexible ladder according to the present invention can slowly and safely reduce the ascending and descending speed of the inner support part, since the high-speed rotational force generated from the electric tool or motor can be reduced by the worm and worm wheel gear and transmitted to the first gear.

[0030] In addition, the drive device of the flexible ladder according to the present invention forms a tool insertion groove into which a hexagonal driver bit or hexagonal wrench can be inserted at one end of the first shaft, thereby enabling the rotational power of an electric tool or a rotary tool to be accurately transmitted to the first shaft.

[0031] In addition, the driving device of the flexible ladder according to the present invention enables an operation process of raising and lowering the inner support part even when the worker stands in front of the outer frame, thereby enabling the worker to perform high-altitude work even in narrow spaces.

[0032] In addition, the drive device of the flexible ladder according to the present invention can protect the power transmission components used to raise and lower the inner support from the overload even if an overload is unintentionally generated during the process of raising and lowering the inner support, thereby preventing damage to each component.

[0033] In addition, the driving device of the flexible ladder according to the present invention can easily set the allowable load of the tray provided on the upper part of the inner support part by adjusting the degree of compression of the elastic member constituting the overload protection part, and can stop the raising and lowering operation of the inner support part according to the load applied to the tray.

[0034] In addition, the drive device of the flexible ladder according to the present invention can prevent interference with the worker's work by not exposing the power transmission components used to raise and lower the inner support part to the outside, and can also provide the worker with a simple product image in appearance.

[0035] Figure 1 is a perspective view showing the configuration of a conventional 'H'-shaped ladder.

[0036] Figure 2 is a perspective view showing the configuration of a conventional 'A' type ladder.

[0037] Figure 3 is a perspective view of a telescopic ladder to which a driving device according to one embodiment of the present invention is applied.

[0038] Fig. 4 is a perspective view showing the inner support portion illustrated in Fig. 3 raised above the outer support portion.

[0039] Fig. 5 is a side view of the interior of the power transmission unit illustrated in Figs. 3 and 4.

[0040] Figure 6 is a front view of an outer support according to one embodiment of the present invention.

[0041] Figure 7 is a side view of the outer frame of the outer support according to one embodiment of the present invention, viewed from the outside.

[0042] Figure 8 is a plan view from above of the upper end of an outer support according to one embodiment of the present invention.

[0043] A cross-sectional view showing the configuration of an overload protection unit according to one embodiment of the present invention of FIG. 9.

[0044] Fig. 10 is a drawing showing the operation of a fixed lever according to one embodiment of the present invention.

[0045] Fig. 11 is a drawing showing the shape of a worm according to another embodiment of the present invention.

[0046] The advantages and features of the present invention and the methods for achieving them will become clear with reference to the embodiments described in detail below together with the accompanying drawings.

[0047] However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and these embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform a person having ordinary skill in the art to which the present invention pertains of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0048] Hereinafter, the driving device of the flexible ladder according to the present invention will be described in detail with reference to FIGS. 3 to 10. In describing the present invention, specific descriptions of related known functions or configurations are omitted to avoid obscuring the gist of the invention.

[0049] FIG. 3 is a perspective view of a telescopic ladder to which a driving device according to an embodiment of the present invention is applied, FIG. 4 is a perspective view showing a state in which the inner support shown in FIG. 3 is raised above the outer support, FIG. 5 is a side view of the inside of the power transmission unit shown in FIGS. 3 and 4 as viewed from the side, FIG. 6 is a front view of the outer support according to an embodiment of the present invention, FIG. 7 is a side view of the outer frame of the outer support according to an embodiment of the present invention as viewed from the outside, FIG. 8 is a plan view of the upper end of the outer support according to an embodiment of the present invention as viewed from above, FIG. 9 is a cross-sectional view showing the configuration of an overload protection unit according to an embodiment of the present invention, FIG. 10 is a view showing an operation of a fixing lever according to an embodiment of the present invention, and FIG. 11 is a view showing a shape of a worm according to another embodiment of the present invention.

[0050] As illustrated in FIGS. 3 and 4, a driving device of a telescopic ladder according to one embodiment of the present invention may be provided in a telescopic ladder (100) including an outer support portion (200) in which a plurality of first step frames (220) are provided at predetermined intervals from each other; and an inner support portion (300) provided inside the outer support portion (220) and in which a plurality of second step frames (320) are provided at predetermined intervals from each other.

[0051] The driving device provided in the above-described flexible ladder (100) may include, as illustrated in FIGS. 1 and 2, a rack gear (R1, R2) provided along the longitudinal direction of the inner support portion (300) on the outer surface of the inner support portion (300); a pinion (P1, P2) connected to the rack gear (R1, R2) and rotatably provided on the inner surface of the outer support portion (200); a power transmission unit (400) that transmits rotational power to the pinion (P1, P2) and is connected to a rotating tool; and an overload protection unit (500) provided in the power transmission unit (400) to prevent the power transmission unit (400) from being damaged when an overload occurs during the process of raising and lowering the inner support portion (300).

[0052] The above outer support member (200) may include a pair of outer frames (210) that are arranged to face each other at a predetermined interval, and a plurality of first footrest frames (220) that connect the pair of outer frames (210) to each other.

[0053] The outer frame (210) of the outer support member (200) may be referred to as a channel-shaped frame. That is, the outer frame (210) may be manufactured in a shape having a 'ㄷ' cross-section in order to accommodate the inner frame (310) of the inner support member (300) to be described later.

[0054] The first footrest frame (220) of the outer support member (200) is a component that a worker steps on and can be placed on the front of the outer frame (210). That is, the longitudinal end of the first footrest frame (220) can be fixedly mounted on the front of the outer frame (210).

[0055] Additionally, the first foothold frame (220) can be arranged in multiple pieces at a predetermined interval along the longitudinal direction of the outer frame (210).

[0056]

[0057] The inner support member (300) may include a pair of inner frames (310) that are arranged to face each other at a predetermined interval, and a plurality of second footrest frames (320) that connect the pair of inner frames (310) to each other.

[0058] The inner frame (310) of the inner support (300) can be manufactured in a shape having a ‘ㄷ’ or ‘I’ cross-section.

[0059] The second footrest frame (320) of the inner support member (300) is a component that a worker steps on and can be placed on the inner side of the inner frame (310). That is, the longitudinal end of the second footrest frame (320) can be fixedly mounted on the inner surface of the inner frame (310).

[0060] Additionally, the second foothold frame (320) can be arranged in multiple pieces at a predetermined interval along the length of the inner frame (310).

[0061] The inner support member (300) configured as described above can be placed in the space between a pair of outer frames (210), as shown in FIG. 3.

[0062] Additionally, the inner support (300) may be raised above a pair of outer frames (210) by rotational power as shown in FIG. 4 and exposed to the upper portion of the outer frames (210).

[0063]

[0064] The above rack gear (R1, R2) can be provided on a pair of inner frames (310) formed by the inner support member (300), as shown in FIGS. 6 and 7.

[0065] That is, the rack gear (R1) may be provided on the outer surface of the inner frame (310) disposed on one side among the pair of inner frames (310). At this time, the rack gear (R1) may be provided along the longitudinal direction of the inner frame (310). In addition, the rack gear (R2) may be provided on the outer surface of the inner frame (310) disposed on the other side among the pair of inner frames (310). At this time, the rack gear (R2) may also be provided along the longitudinal direction of the inner frame (310). Here, the outer surface of the inner frame (310) may be referred to as a surface facing the inner surface of the outer frame (210).

[0066]

[0067] The above pinion (P1, P2) may be provided on a pair of outer frames (210) formed by the outer support member (200), as illustrated in FIG. 8.

[0068] That is, the pinion (P1) can be rotatably mounted on the inner surface of the outer frame (210) disposed on one side among the pair of outer frames (210). In addition, the pinion (P2) can be rotatably mounted on the inner surface of the outer frame (210) disposed on the other side among the pair of outer frames (210). Here, the inner surface of the outer frame (210) can be referred to as a surface facing the outer surface of the inner frame (310).

[0069]

[0070] The power transmission unit (400) may be mounted on the outer surface of an outer frame (210) disposed on one side of a pair of outer frames (210) constituting the outer support unit (200), as illustrated in FIGS. 5 to 9.

[0071] The power transmission unit (400) may include a first shaft (410) that receives power from the rotating tool and rotates; a worm (420) provided on the first shaft (410); a first gear (430) connected to the worm (420); and a second shaft (440) that receives rotational force generated from the first gear (430) and rotates and is arranged parallel to the first foot frame (220) or the second foot frame (320).

[0072] The above first shaft (410) can be said to be a component directly connected to a rotating tool (t). That is, a tool insertion groove (412) can be formed at one end in the longitudinal direction of the first shaft (410).

[0073] The first shaft (410) may be arranged in a direction intersecting the first footrest frame (220) of the outer support member (200) or the second footrest frame (320) of the inner support member (300). Accordingly, the tool insertion groove (412) may be exposed to the front side of the outer support member (200), as illustrated in FIGS. 3 and 4.

[0074] For reference, the rotary tool (t) combined with the tool insertion groove (412) may include various known tools such as an electric driver, a screwdriver, and a wrench.

[0075] The above worm (420) can be rotatably mounted on a longitudinal portion of the first shaft (410).

[0076] The above first gear (430) rotates in conjunction with the rotation of the worm (420), can be rotatably mounted on a casing mounted on the outer surface of the outer frame (210), and can rotate in conjunction with a worm wheel (421) directly connected to the worm (420).

[0077] Additionally, the second shaft (440) can rotate in conjunction with the first gear (430).

[0078] As shown in FIGS. 6 and 8, the second shaft (440) is provided inside the first foothold frame (220) positioned at the top of the outer frame (210) among the plurality of first foothold frames (220) constituting the outer support member (200), and can be rotated inside the first foothold frame (220).

[0079] That is, the second shaft (440) can be arranged along the length of the first foothold frame (220) inside the first foothold frame (220) so as not to interfere with the movement of the worker.

[0080] Therefore, among the plurality of first foothold frames (220), it is preferable that the first foothold frame (220) placed at the top of the outer frame (210) has a hollow shape with an empty interior, as shown in FIGS. 6 to 8.

[0081] One longitudinal end of the second shaft (440) may be exposed to the outer surface of an outer frame (210) disposed on one side of a pair of outer frames (210), as shown in FIGS. 6 and 8.

[0082] Additionally, the longitudinal other end of the second shaft (440) may be exposed to the outer surface of the outer frame (210) disposed on the other side among the pair of outer frames (210), as shown in FIGS. 6 and 8.

[0083] Meanwhile, as shown in FIGS. 5, 6 and 8, a second gear (450) that is connected to and rotates with the first gear (430) may be provided at one end of the longitudinal direction of the second shaft (440).

[0084] The above second gear (450) can be said to be a component that transmits the rotational force generated from the first gear (430) to the second shaft (440).

[0085] Therefore, when the first gear (430) rotates, the second gear (450) and the second shaft (440) can rotate.

[0086] As illustrated in Fig. 8, a third gear (460) may be provided at the longitudinal end of the second shaft (440). The third gear (460) may be a component that transmits rotational power to a pinion (P2) provided on an outer frame (210) disposed on the other side of a pair of outer frames (210).

[0087] The third gear (460) may be connected to the fourth gear (470) to transmit rotational power to the pinion (P2).

[0088] The fourth gear (470) is rotatably mounted on the outer frame (210) positioned on the other side of the pair of outer frames (210), and can be positioned on the outer surface of the outer frame (210).

[0089] In addition, it can be said that the fourth gear (470) shares the same rotational axis with the pinion (P2). In other words, the pinion (P2) may be provided at one end of the rotational axis while being arranged on the inner surface of the outer frame (210), and the fourth gear (470) may be provided at the other end of the rotational axis while being arranged on the outer surface of the outer frame (210).

[0090] Therefore, when the third gear (460) rotates, the fourth gear (470) and the pinion (P2) can rotate simultaneously.

[0091] When the pinion (P2) provided on the outer frame (210) positioned on the other side among a pair of outer frames (210) rotates, the rack gear (R2) provided on the inner frame (310) positioned on the other side among a pair of inner frames (310) can mesh with the pinion (P2).

[0092] In addition, the rack gear (R1) of the inner frame (310) arranged on one side among a pair of inner frames (310) can mesh with the pinion (P1) of the outer frame (210) arranged on one side.

[0093] As above, when the pinion (P1, P2) and the rack gear (R1, R2) mesh with each other, the inner support (300) can be raised or lowered on the outer support (200).

[0094] For example, when a worker rotates the electric driver in one direction while inserting the tip of the electric driver into the tool insertion groove (412) formed at the longitudinal end of the first shaft (410), the worm (420) can rotate in one direction in conjunction with the rotation of the first shaft (410).

[0095] Then, the first gear (430) that shares the same rotation axis as the worm wheel (421) that is directly connected to the worm (420) can rotate in one direction.

[0096] Next, as the second gear (450) meshed with the first gear (430) rotates in one direction, the second shaft (440) connected to the second gear (450) also rotates in one direction.

[0097] When the second shaft (440) is rotated, the third gear (460) provided at the longitudinal end of the second shaft (440) and the fourth gear (470) connected to the third gear (460) can be rotated sequentially.

[0098] Then, the pinion (P2) sharing the same rotation axis as the fourth gear (470) can rotate and mesh with the rack gear (R2).

[0099] When the above state is achieved, the inner support (300) can be raised upward on the outer support (200).

[0100] Conversely, when the worker rotates the electric driver in the other direction while inserting the tip of the electric driver into the tool insertion groove (412) formed at the longitudinal end of the first shaft (410), the inner support (300) that was raised above the outer support (200) can be lowered and returned to its original state.

[0101] Meanwhile, the worm (420) may be manufactured so that its teeth have different heights, as illustrated in FIG. 11. For example, the worm (420) may be manufactured so that the height gradually decreases from the teeth positioned at the longitudinal ends toward the teeth positioned in the middle.

[0102] Accordingly, the above worm (420) may have the shape of a drum.

[0103] The worm (420) in the shape of a drum has the advantage of not only smoothly transmitting power due to the increased contact area with the worm wheel (421), but also of high durability. Therefore, the worm (420) has the advantage of maintaining durability and smoothly transmitting power even when manufactured from plastic materials as well as metal, thereby reducing manufacturing costs.

[0104]

[0105] The above overload protection unit (500) may include, as illustrated in FIGS. 5 and 9, a body (510) that is rotatably provided on the first shaft (410) and connected to the worm (420); a ball (520) that contacts a stepped surface (411) formed on a portion of the outer circumferential surface of the first shaft (410) via a screw hole formed in the body (510); an elastic member (530) that is inserted into the screw hole and has one longitudinal end in contact with the ball (520); and an adjusting screw (540) that presses the other longitudinal end of the elastic member (530) and is fastened to the screw hole.

[0106] The above body (510) can be fixedly connected to one end of the longitudinal direction of the worm (420). Therefore, when the worm (420) rotates, the body (510) can also rotate.

[0107] The above ball (520) is made of metal and can come into contact with the step surface (411) of the first shaft (410) through a screw hole formed in the body (510).

[0108] For reference, a groove or hole may be formed on the step surface (411) of the first shaft (410) into which a portion of the ball (520) can be inserted and seated.

[0109] The elastic member (530) is positioned inside a screw hole formed in the body (510) and can be compressed or tensioned by the adjusting screw (540). For reference, the elastic member (530) can be implemented as an elastic spring, as illustrated in FIG. 9.

[0110] The above adjusting screw (540) can be inserted into a screw hole formed in the body (510) to pressurize the longitudinal other end of the elastic member (530). Then, the elastic member (530) is compressed inside the screw hole of the body (510), and in conjunction with this, the ball (520) presses the step surface (411) of the first shaft (410).

[0111] The overload protection unit (500) configured as described above can rotate together with the first shaft (410) when no load is applied to the inner support unit (300). That is, the ball (520) can rotate together with the first shaft (410) while pressing the step surface (411) of the first shaft (410).

[0112] Conversely, if an overload occurs during the process of raising and lowering the inner support member (300), the overload protection member (500) and the worm (420) are in a stopped state.

[0113] That is, if the overload generated in the inner support member (300) is greater than the elastic pressing force of the elastic member (530) that presses the ball (520) toward the step surface (411) of the first shaft (410), the first shaft (410) may not rotate together with the overload protection member (500) and the worm (420) and may idle alone.

[0114] In detail, the body (510), ball (520), elastic member (530) and adjusting screw (540) of the overload protection unit (500) are in a state of being stopped at a certain position based on the rotation center of the first shaft (410), and only the first shaft (410) can rotate.

[0115] Accordingly, even if an overload occurs during the process of raising and lowering the inner support member (300), only the first shaft (410) rotates, so that power transmission against the overload is not performed, and thus damage to the first gear (430), second shaft (440), second gear (450), third gear (460), fourth gear (470), pinion (P1, P2), and rack gear (R1, R2) can be prevented. In addition, the safety of the user can also be ensured.

[0116] In addition, the overload protection unit (500) can stop the lifting operation of the inner support unit (300) even if the power tool or the driving motor (M, see Fig. 5) is operated when the inner support unit (300) reaches the lifting limit or lowering limit during the lifting process, and can also prevent the power transmission unit (400) from being damaged even if an overload occurs due to an item exceeding the allowable load being loaded on the tray.

[0117]

[0118] Meanwhile, the driving device of the flexible ladder according to one embodiment of the present invention may further include a fine adjustment member (600), as illustrated in FIG. 5.

[0119] The above fine adjustment member (600) can be said to be a component that is rotatably connected to the first shaft (410).

[0120] The above fine adjustment member (600) is a component that allows a worker to manually adjust the height of the inner support member (300) raised or lowered on the outer support member (200). It can be said to be a component used when a worker needs to directly finely adjust the degree of elevation of the inner support member (300).

[0121] For example, when the first shaft (410) is rotated using an electric driver, it is very difficult to accurately control the elevation height of the inner support member (300) by the rotation speed of the electric driver. At this time, the worker can accurately control the elevation height of the inner support member (300) by rotating the fine adjustment member (600) provided on the first shaft (410) in one or the other direction.

[0122] Although specific embodiments of the present invention have been described so far, it is obvious that various modifications are possible within the scope of the present invention.

[0123] For example, in one embodiment of the present invention, the first shaft (410) is rotated using a rotary tool (t) such as an electric driver, an auxiliary handle, a driver, etc., but the present invention is not limited thereto, and as illustrated in FIG. 5, the first shaft (410) may be rotated by connecting the output shaft of the drive motor (M) connected to the battery to the longitudinal other end of the first shaft (410). At this time, it is preferable that a clutch (C) be provided between the drive motor (M) and the first shaft (410).

[0124] In addition, as illustrated in FIGS. 3 and 4, the outer support member (200) may further be provided with an auxiliary frame (230). That is, an auxiliary frame (230) may be provided rotatably on the rear surface of each of the pair of outer frames (210) constituting the outer support member (200).

[0125] Accordingly, the support capacity and safety of the flexible ladder (100) can be further increased by the auxiliary frame (230).

[0126] And, as illustrated in Fig. 10, a fixed lever (700) may be provided on the outer support member (200). The fixed lever (700) has a configuration that rotates in one direction or the other, and serves to prevent the inner support member (300) raised on the outer support member (200) from unintentionally moving due to an external force.

[0127] For example, when the fixed lever (700) is rotated in one direction, the inner support member (300) can be maintained in a fixed state on the outer support member (200). Conversely, when the fixed lever (700) is rotated in the other direction, the inner support member (300) can be changed to a state in which it can be raised or lowered. For reference, the locking structure of the fixed lever (700) by rotating in one or the other direction is a configuration that can be easily implemented by those skilled in the art, and therefore, in the specification of the present invention, a detailed description of the configuration is omitted so as not to obscure the gist of the invention.

[0128] Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the claims described below, but also by equivalents of the claims.

[0129] The present invention can be sold and used in various industrial fields that require ladders.

Claims

1. An outer support member in which a plurality of first foothold frames are provided at a predetermined interval from each other; and A telescopic ladder is provided, including an inner support provided inside the outer support and a plurality of second step frames provided at a predetermined interval from each other; A rack gear provided along the longitudinal direction of the inner support on the outer surface of the inner support; A pinion connected to the above rack gear and rotatably provided on the inner surface of the outer support; and A drive device for a telescopic ladder, comprising a power transmission unit that transmits rotational power to the above pinion and is connected to a rotating tool.

2. In paragraph 1, The above power transmission unit, A first shaft arranged on one outer surface of the outer support and rotated by receiving power from the rotating tool; A worm provided on the first shaft; A first gear sharing the same rotation axis as the worm wheel directly connected to the worm; and A drive device for a telescopic ladder, characterized in that it includes a second shaft that is rotated by receiving rotational force generated from the first gear and is arranged parallel to the first step frame or the second step frame.

3. In paragraph 2, A drive device for a telescopic ladder, characterized in that the first shaft is arranged in a direction intersecting the first step frame or the second step frame.

4. In paragraph 3, A drive device for a telescopic ladder, characterized in that the second shaft is provided inside the first step frame arranged at the uppermost end of the outer support part among a plurality of first step frames, and is arranged along the longitudinal direction of the first step frame.

5. In paragraph 2, A second gear connected to the first gear is provided at one end of the longitudinal direction of the second shaft; A drive device for a telescopic ladder, characterized in that a third gear is provided at the longitudinal other end of the second shaft to transmit rotational power to the pinion rotatably provided on the other inner surface of the outer support.

6. In paragraph 2, A driving device for a telescopic ladder, characterized in that it includes an overload protection unit provided in the power transmission unit and preventing the power transmission unit from being damaged when an overload occurs during the process of raising and lowering the inner support unit.

7. In paragraph 6, The above overload protection unit, A body that is rotatable on the first shaft and connected to the worm; A ball that comes into contact with a stepped surface formed on a portion of the outer surface of the first shaft through a screw hole formed in the body; An elastic member inserted into the screw hole and having one longitudinal end in contact with the ball; and A driving device for a telescopic ladder, characterized in that it includes an adjusting screw that presses the longitudinal end of the elastic member and is fastened to the screw hole.

8. In paragraph 7, A drive device for a telescopic ladder, characterized in that when an overload occurs during the process of raising and lowering the inner support, the overload protection unit and the worm are in a stopped state and the first shaft rotates idle.

9. In paragraph 7, A drive device for a telescopic ladder, characterized in that it further includes a fine adjustment member rotatably connected to the first shaft and connected to the body.

10. In paragraph 1, A drive device for a flexible ladder, characterized in that the power transmission unit is connectable to a drive motor connected to a battery.

11. In paragraph 2, The teeth formed by the above worms have different heights, A driving device for a telescopic ladder characterized by having a shape of a waist drum, manufactured in a form in which the height gradually decreases from the teeth arranged at the longitudinal end of the worm toward the teeth arranged in the middle.

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