CN110847800A

CN110847800A - Extension ladder

Info

Publication number: CN110847800A
Application number: CN201911296106.XA
Authority: CN
Inventors: 黄崇华
Original assignee: Chonghua Technology Yongkang Co Ltd
Current assignee: Chonghua Technology Yongkang Co Ltd
Priority date: 2019-04-08
Filing date: 2019-12-16
Publication date: 2020-02-28
Also published as: CN111155922A; CN110847800A8; CN109826554A

Abstract

The invention provides a telescopic ladder, which at least comprises: two adjacent ladder sections that can slide relatively, every ladder section includes at least: two vertical sections and a transverse section connected between the two vertical sections; the vertical section of the inner ladder section is slidably arranged on the vertical section of the outer ladder section; the inboard ladder section still includes: the first elastic locking device is arranged on the transverse section of the ladder section on the inner side; the first elastic locking device comprises teeth and a first elastic device which is connected with and controls the teeth to move; the outer ladder sections further comprise: the rack is arranged on the vertical section of the ladder section on the outer side; the rack is meshed with the teeth. The invention adjusts the two adjacent ladder sections to the required height by utilizing the occlusion or locking of the rack and the teeth, thereby realizing the adjustment of the middle position.

Description

Extension ladder

The present application claims application No.: 2019102780068, title of the invention: extension ladder, application date: 2019-04-08.

Technical Field

The invention relates to the field of ladders, in particular to a telescopic ladder, namely a telescopic ladder.

Background

The existing extension ladder is formed by connecting a plurality of sections of ladder sections or ladder units, the extension adjustment is that the adjacent two sections are completely pulled apart or are completely compressed to one section, the distance between the adjacent two sections is only two end values, the position between the adjacent two sections cannot be adjusted to the intermediate value between the complete pulling apart and the complete compression as required, and the adjustment and the use are inconvenient.

In summary, the following problems exist in the prior art: the prior extension ladder can only be completely pulled out or compressed between two adjacent sections, and cannot be adjusted in the middle position between the complete pulling out and the complete compression.

Disclosure of Invention

The invention provides an extension ladder, which aims to solve the problem that the middle position of the existing extension ladder cannot be adjusted.

To this end, the invention proposes an extension ladder comprising at least:

two adjacent ladder sections capable of sliding relatively are respectively an inner ladder section and an outer ladder section,

each ladder section at least comprises: two vertical sections and a transverse section connected between the two vertical sections; the vertical section of the inner ladder section is slidably arranged on the vertical section of the outer ladder section;

the inboard ladder section still includes: the first elastic locking device is arranged on the transverse section of the ladder section on the inner side; the first elastic locking device comprises teeth and a first elastic device which is connected with and controls the teeth to move;

the outer ladder sections further comprise: the rack is arranged on the vertical section of the ladder section on the outer side;

the rack is meshed with the teeth.

Further, in the above-mentioned case,

the rack is arranged on the inner side of the vertical section of the ladder section on the outer side, and the vertical section of the ladder section on the inner side is provided with a first through hole for the tooth and/or the first elastic device to enter and exit; the rack is intersected with an extension line of the through hole and faces the first through hole; the teeth and/or the first elastic device are/is arranged in the first through hole in a telescopic way; or the transverse section of the inner ladder section seals the two vertical sections of the inner ladder section, the bottom surface of the transverse section of the inner ladder section is lower than the bottom surfaces of the two vertical sections of the inner ladder section, a connecting hole for the tooth and/or the first elastic device to enter and exit is formed in the end part of the transverse section of the inner ladder section, and the rack is intersected with the extension line of the connecting hole and faces the connecting hole; the teeth and/or the first elastic device can be arranged in the connecting hole in a telescopic mode. .

Further, the rack is flat or linear.

Further, in the above-mentioned case,

the first elastic locking device specifically comprises: the upper box body 86, the lower box body 85 which is arranged at the bottom of the upper box body 86 and can move up and down relative to the upper box body 86, and a first spring 850 which is arranged between the upper box body 86 and the lower box body 85; the two sides of the upper box body 86 are provided with second through holes 860, the top of the lower box body 85 is provided with a guide part 855 capable of sliding in the upper box body 86, the bottom of the lower box body 85 extends out of the bottom of the upper box body 86, and the top of the lower box body 85 is also provided with a connecting rod telescopic channel communicated with the second through holes 860; the top of the lower box 85 is also provided with an inclined plane 851 connected to the guide 855 and extending obliquely;

the first elastic locking device further comprises: the gear comprises a shell 80, a cavity 800 of the shell, a connecting rod 82 extending into the shell and capable of moving in the cavity 800 of the shell, a sliding part 821 which is arranged at a first end of the connecting rod 82 and capable of sliding on an inclined surface 851, a locking part 81 which is arranged at a second end of the connecting rod 82, is positioned in the cavity 800 of the shell and capable of extending out of the cavity 800 of the shell, and a second spring 820 which is sleeved on the connecting rod 82 and abutted against the locking part 81, wherein the teeth are arranged at the edge of the locking part 81; the connecting rod 82 is arranged in the second through hole 860 and the connecting rod telescopic channel in a telescopic way; wherein, the shell 80 is located at the second end of the connecting rod 82, and the cavity 800 of the shell penetrates through the shell 80; the first elastic locking device further comprises: the fifth spring 84 is positioned in the cavity 800 of the shell, and the fifth spring 84 is arranged between the inner wall of the shell 80 and the locking part 81 and is sleeved on the connecting rod 82;

the horizontal section has a hollow structure for accommodating the upper box body 86, the shell 80 and the connecting rod 82, and a third through hole for the lower box body 85 to stretch or press the lower box body 85 is formed in the bottom of the horizontal section.

Further, the inner ladder section further comprises: a second locking device, the second locking device comprising:

a blind hole 811 provided in the locking portion 81;

a first slider 813 which is arranged in the blind hole 811 and can move up and down in the blind hole;

a first limiting step for limiting the downward movement of the first sliding block 813 is arranged in the blind hole 811;

a positioning column 8131 provided at the bottom of the first slider 813 and capable of entering and exiting in the opening end; the aperture of the positioning column 8131 is smaller than that of the first sliding block 813;

the third spring 812 is tightly propped between the closed end of the blind hole 811 and the first sliding block 813;

a locking sleeve 83 provided in the housing 80 below the locking portion 81; the locking sleeve 83 has a top opening and a bottom opening;

the caliber of the top opening is larger than that of the positioning column 8131; the top opening 830 has a locking position in centered communication with the blind hole 811 and an unlocking position staggered from the blind hole 811;

a button 835 movably disposed in a bottom opening of the locking sleeve 83;

a second limiting step for limiting the upward movement of the button 835 is arranged at the top opening, and the distance between the second limiting step and the top of the top opening is more than 0;

the fourth spring 832 is tightly propped between the limit clamping platform and the button 835.

Further, each vertical section comprises: a first sliding surface 91 and a second sliding surface 92 which are parallel and both of which are flat; the first sliding surface is positioned on the inner side of the second sliding surface, and the second sliding surface of the inner vertical section is positioned on the inner side of the first sliding surface of the outer vertical section; the sliding surface formed between the outside vertical section and the inside vertical section includes: and a plane sliding pair or a plane sliding friction surface formed by the first sliding surface of the outer vertical section and the second sliding surface of the inner vertical section.

Furthermore, the first sliding surface and the second sliding surface are respectively provided with two ends which are respectively a first end and a second end;

each vertical section further comprises: a first mounting surface 93 connected to a first end of the first sliding surface and a first end of the second sliding surface, a second mounting surface 94 connected to a second end of the second sliding surface and a second end of the second sliding surface;

the first sliding surface, the second sliding surface, the first mounting surface and the second mounting surface form a parallelogram and four intersection angles respectively positioned in four quadrants; the four intersection angles are respectively: a first intersection angle M positioned in a first quadrant, a second intersection angle N positioned in a second quadrant, a third intersection angle P positioned in a third quadrant and a fourth intersection angle Q positioned in a fourth quadrant;

a first hook 95 is arranged at the first intersection angle; the first hook includes: the device comprises a first vertical edge 951, a first transverse edge 952 connected with the first vertical edge, and a second vertical edge 953 connected with the first transverse edge, wherein the first vertical edge is parallel to the second vertical edge, the length of the first vertical edge is greater than that of the second vertical edge, and the first transverse edge seals a first end of the first vertical edge and a first end of the second vertical edge; the first vertical edge is arranged close to the first sliding surface and extends towards the direction far away from the second mounting surface, and the outer side of the second vertical edge is flush with the first sliding surface; the first vertical edge 951, the second vertical edge 953 and the first transverse edge 952 form a first L-shaped slide rail;

second intersection angle department is equipped with second draw-in groove 96, and the second draw-in groove includes: a third vertical edge 961, a third transverse edge 962 connecting the third vertical edge; the third perpendicular limit is located the nodical and with first perpendicular limit syntropy extension of first glide plane and first installation face, the second draw-in groove still includes: a fourth transverse edge 963 connected to the third vertical edge and extending in a direction opposite to the first transverse edge, and a fourth vertical edge 964 connected to the fourth transverse edge and extending in the same direction as the third vertical edge, wherein the third transverse edge 962, the third vertical edge 961, the fourth vertical edge 964 and the fourth transverse edge 963 form a first L-shaped sliding slot 967; the first L-shaped sliding groove is matched with the first L-shaped sliding rail in shape.

Further, in the above-mentioned case,

the first hook further includes: a fifth transverse edge 954 connecting the first vertical edges and a fifth vertical edge 955 connecting the fifth transverse edge, the fifth transverse edge being parallel to and extending in the same direction as the first transverse edge, the fifth vertical edge being parallel to and extending in the same direction as the second vertical edge; the fifth transverse edge and the fifth vertical edge form a second L-shaped sliding rail; the second L-shaped slide rail is positioned between the first L-shaped slide rail and the first mounting surface, and the fifth vertical edge is flush with the first sliding surface;

the second card slot further includes: a sixth transverse side 965 connected to the third vertical side and extending in the same direction as the third transverse side, a sixth vertical side 966 connected to the sixth transverse side and extending in the same direction as the fourth vertical side, and a second L-shaped sliding groove 968 formed by the sixth transverse side and the sixth vertical side; the bottom surface of the sixth transverse edge is flush with the top surface of the first mounting surface;

the shape of the second L-shaped sliding groove is matched with that of the second L-shaped sliding rail.

Further, in the above-mentioned case,

the second card slot further includes: a sloping edge 969 extending obliquely from the third transverse edge 962 in a direction away from the third vertical edge 961, wherein a trapezoidal limiting groove 9690 is formed between the sloping edge 969 and the fourth vertical edge 964 and the sixth vertical edge 966, and the minimum width of the limiting groove 9690 is greater than the width of the first vertical edge 951.

Further, in the above-mentioned case,

each vertical section further comprises: the sliding rack comprises a mounting groove 910 recessed from the first sliding surface 91 to the second sliding surface 92 side, and a rack mounted in the mounting groove 910, wherein the thickness of the rack is smaller than that of the mounting groove 910.

Further, in the above-mentioned case,

the mounting groove 910 is rectangular, and the mounting groove 910 includes: two bending sections 913 formed by bending the first sliding surface 91 to one side of the second sliding surface 92, and a groove bottom 911 connected between the two bending sections 913, wherein the two bending sections 913 and the groove bottom 911 form three rectangular sides;

each vertical section further comprises: and the rack limiting plates 912 respectively extend from each bent section 913 to the bent section 913 on the opposite side, the rack limiting plates 912 are parallel to the first sliding surface 91 and the groove bottom 911, and the distance between the groove bottom 911 and the first sliding surface 91 is greater than the distance between the outer edge of the rack limiting plate 912 and the groove bottom 911.

In the invention, in two adjacent ladder sections capable of sliding relatively, the vertical section of the ladder section at the inner side is provided with teeth, and the rack on the vertical section of the ladder section at the outer side can adjust the two adjacent ladder sections to the required height by utilizing the occlusion or locking of the rack and the teeth as required in the process of extension and retraction of the ladder sections or the ladder units, thereby realizing the adjustment of the middle position.

Furthermore, the two adjacent vertical sections of the ladder adopt unilateral sliding or contact, so that the thickness of each vertical section can be the same, and the problem that the strength of the whole ladder is influenced because the ladder section at the top is thinner and has weaker strength in the traditional cylindrical or telescopic structure is solved. In addition, the height of the ladder of the invention can be much smaller than that of the traditional cylinder or telescopic structure after the ladder is compressed or folded, and the ladder is more convenient to carry.

Drawings

Fig. 1 is a schematic perspective view of an extended state of an extension ladder according to a first embodiment of the present invention, wherein the extension ladder has 9 ladder sections or ladder units;

fig. 2 is a perspective view of the telescopic ladder of fig. 1 in a compressed state;

FIG. 3 is a schematic front view of the structure of FIG. 2;

FIG. 4 is a schematic top view of the structure of FIG. 2;

fig. 5 is a front view schematically illustrating the structure of an extension ladder according to a second embodiment of the present invention, wherein the extension ladder has 3 ladder sections or ladder units;

fig. 6 is a perspective view of a telescopic ladder according to a third embodiment of the present invention, wherein the telescopic ladder has 2 ladder sections or ladder units, and a part of the housing or frame in the horizontal and vertical sections is removed;

FIG. 7 is a schematic perspective view of another angle shown in FIG. 6;

FIG. 8 is a schematic perspective view of a first locking device of the present invention;

FIG. 9 is a schematic perspective view of FIG. 8 with the upper case removed;

FIG. 10 is a front view schematic of the structure of FIG. 9;

FIG. 11 is an exploded view of the upper and lower cases of the present invention;

FIG. 12 is a schematic external perspective view of a second locking mechanism of the present invention;

FIG. 13 is a front view schematic of the structure of FIG. 12;

FIG. 14 is a schematic bottom view of the structure of FIG. 12;

FIG. 15 is a cross-sectional view A-A of FIG. 14, wherein the locating posts are offset from the top openings;

FIG. 16 is a cross-sectional view of the alignment post of the present invention aligned with the top opening;

FIG. 17 is a schematic cross-sectional view of the locating post of the present invention entering the top opening;

FIG. 18 is a schematic perspective view of a first angle of a vertical section of the present invention;

FIG. 19 is a perspective view of a second angle of a vertical section of the present invention;

FIG. 20 is a top structural schematic view of a vertical section of the present invention;

FIG. 21 is a top view schematic of the assembled two vertical sections of the present invention;

fig. 22 is a top view of the assembled two vertical sections of the present invention with racks installed.

The reference numbers illustrate:

1. ladder sections (ladder units); 7. a transverse section; 9. a vertical section;

80. a housing; 81. a locking portion; 83. a locking sleeve; 86. an upper box body; 85. a lower box body; 87. an end cap;

850. a first spring; 860. a second perforation; 855. a guide portion; 857. a pressing block; 859. a connecting rod telescopic channel; 800. a cavity; 82. a connecting rod; 851. a bevel; 820. a second spring; 821. a sliding part; 810. teeth; 811. blind holes; 813. a first slider; 8131. a positioning column; 812. a third spring; 830. the top is open; 835. a button; 832. a fourth spring; 84. a fifth spring;

91. a first sliding surface; 92. a second sliding surface; 93. a first mounting surface; 94. a second mounting surface; 95. a first hook; 951. a first vertical edge; 952. a first transverse edge; 953. a second vertical edge;

96. a second card slot; 961. a third vertical edge; 962. a third transverse edge; 963. a fourth transverse edge; 964. a fourth vertical edge; 967. a first L-shaped chute; 960. a sixth transverse edge;

954. a fifth transverse edge; 955. a fifth vertical side; 965. a sixth transverse edge; 966. a sixth vertical side; 968. a second L-shaped chute; 969. a bevel edge; 9690. a limiting groove;

910. mounting grooves; 90. a rack;

913. bending sections; 911. the bottom of the tank;

912. rack limiting plate

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, the present invention will now be described with reference to the accompanying drawings.

As shown in fig. 1, 2, 3, 4, the present invention proposes an extension ladder, which at least comprises:

two adjacent ladder sections 1 (ladder units) capable of sliding relatively are respectively an inner ladder section and an outer ladder section, the inner ladder section is opposite to the outer ladder section, the inner side of the inner ladder section can be provided with more inner ladder sections, the outer side of the outer ladder section can be provided with more outer ladder sections, and in the whole extension ladder, the middle ladder section is an inner ladder section and an outer ladder section, so that the plurality of ladder sections are sequentially arranged from inside to outside from top to bottom to form the extension ladder with the plurality of ladder sections;

the extension ladder of the present invention may be two ladder sections or ladder units in fig. 6 and 7, may also be 3 ladder sections or ladder units in fig. 5, may also be 9 ladder sections or ladder units in fig. 1, 2, 3, 4, and so on, and may also be other number of ladder sections or ladder units not shown in the figure, for example, 4 ladder sections or ladder units, 5 ladder sections or ladder units, 6 ladder sections or ladder units, or 7 ladder sections or ladder units;

as shown in fig. 5, 6 and 7, each ladder section 1 at least comprises: two vertical sections 9 and a transverse section 7 connected between the two vertical sections; the transverse sections 7 are used for climbing and supporting a user, the vertical sections 9 play a role of supporting the transverse sections 7 on one hand and providing a sliding track on the other hand, the vertical section 9 of the inner ladder section is slidably arranged on the vertical section 9 of the outer ladder section, and a sliding surface is arranged between the vertical section 9 of the inner ladder section and the vertical section 9 of the outer ladder section;

as shown in fig. 5, 6, 7, 8, 9 and 10, the inner ladder section 1 further includes: the first elastic locking device is arranged on the transverse section 7 of the ladder section on the inner side; the first elastic locking device comprises teeth 810 and a first elastic device (the first elastic device comprises a spring and a connecting rod connected with the spring, etc.) which is connected with and controls the teeth to move;

the outer ladder sections further comprise: a rack 90 provided on the vertical section 9 of the outside ladder section;

the rack 90 is meshed or meshed with the teeth 810 to form locking (for example, unidirectional locking), the locking between the vertical section 9 of the outer ladder section and the transverse section 7 of the inner ladder section can be formed by meshing the rack 90 with the teeth 810, and the locking between the vertical section 9 of the outer ladder section and the transverse section 7 of the inner ladder section can be positioned to the locking position in the unit of the tooth pitch of the rack according to actual needs by having a plurality of continuous locking positions or intermediate positions. For example, the sliding distance of the vertical section 9 of the inner ladder section relative to the vertical section 9 of the outer ladder section is 30cm to 50cm, and the pitch is 0.5cm to 2cm, so that the locking adjustment of up to 100 intermediate positions can be realized, and the sliding distance of the vertical section 9 of the inner ladder section relative to the vertical section 9 of the outer ladder section is 30cm and the pitch is 1cm, for example, the position adjustment of 1cm between two ladder sections at each time can be realized, and the adjustment precision is improved by dozens of times. Of course, position adjustments of 5cm, 8cm or other values at a time may also be implemented. The rack 90 and the teeth 810 are meshed to form unidirectional locking, namely locking downwards and free upwards, and the unidirectional locking is realized by adjusting the angles of the rack and the teeth; at the locking position, pulling open between two ladder sections can not receive locking device's restraint, can pull open, but, the compression between two ladder sections has been locked, like this, guarantees that the user steps on when horizontal segment (horizontal ladder), and horizontal segment (horizontal ladder) can not move down, guarantees user's safety.

Further, in the above-mentioned case,

each ladder section at least comprises two vertical sections and a transverse section, the two vertical sections and the transverse section form an H shape, and the vertical sections and the transverse section can form a right angle or an angle smaller than 90 degrees; further, as shown in fig. 1, 2, 3, 5 and 7, the topmost ladder section can be arranged with one more transverse section than the other ladder sections to increase the climbing height, such as two vertical sections and two transverse sections in the topmost ladder section, and two vertical sections and one transverse section in the other ladder sections;

fig. 6 and 7 show the internal structure of the ladder section by removing part of the external part, as shown in fig. 6 and 7, the rack 90 is arranged on the inner side of the vertical section 9 of the outer ladder section, and the vertical section 9 of the inner ladder section is provided with a first through hole for the tooth and/or the first elastic device to enter and exit, namely the tooth 810 can pass through the vertical section 9 of the inner ladder section; the rack 90 intersects an extension line of the through hole and faces the first through hole; the teeth 810 are telescopically disposed in the first bore.

Or, do not establish first perforation on the vertical section 9 of inboard ladder section, the horizontal segment of inboard ladder section seals two vertical sections of inboard ladder section, tooth and/or first resilient means stretch out from the horizontal segment of inboard ladder section, like this, can reduce the processing degree of difficulty of vertical section, improve the support intensity of vertical section.

For example, the length of the transverse section of the inner ladder section is greater than or equal to the sum of the distance between the two vertical sections of the inner ladder section and the width of the two vertical sections of the inner ladder section, the bottom surface of the transverse section of the inner ladder section is lower than the bottom surfaces of the two vertical sections of the inner ladder section, a connecting hole for the tooth and/or the first elastic device to enter and exit is formed in the end part of the transverse section of the inner ladder section, and the rack is intersected with the extension line of the connecting hole and faces the connecting hole; the teeth and/or the first elastic device can be arranged in the connecting hole in a telescopic mode.

Further, as shown in fig. 6 and 7, the rack 90 has a flat plate shape or a straight line shape, i.e., a straight rack. For the circular or curved rack, on one hand, the arrangement range of the rack can be reduced, the processing and installation difficulty is reduced, the integral thickness and weight of the vertical section 9 are reduced, and on the other hand, the stability during occlusion can be improved.

Further, as shown in FIGS. 8, 9, 10 and 11,

the first elastic locking device specifically comprises: an upper box body 86 fixed in the transverse section by a rivet or a screw, a lower box body 85 arranged at the bottom of the upper box body 86 and capable of moving up and down relative to the upper box body 86, an end cover 87 arranged at the bottom of the lower box body 85 and connected with the upper box body 86, and a first spring 850 arranged between the upper box body 86 and the lower box body 85; the end cover 87 is used for limiting the lower box body 85 and preventing the lower box body 85 from separating from the upper box body 86;

as shown in fig. 11, the two sides of the upper box body 86 are provided with second through holes 860, the top of the lower box body 85 is provided with a guide 855 capable of sliding in the upper box body 86, the bottom of the lower box body 85 extends out of the bottom of the upper box body 86, and the top of the lower box body 85 is further provided with a link rod telescopic passage 859 communicated with the second through holes 860 so as to accommodate the extension and contraction of the link rod 82; the top of the lower box 85 is also provided with an inclined plane 851 connected to the guide 855 and extending obliquely;

as shown in fig. 12, 13, 14, 15, 16 and 17, the first elastic locking means further includes: the shell 80 fixed on the transverse section 7 by rivets, welding or screws, a cavity 800 of the shell, a connecting rod 82 extending into the shell and capable of moving in the cavity 800 of the shell, a sliding part 821 arranged at a first end of the connecting rod 82 and capable of sliding on the inclined surface 851, a locking part 81 arranged at a second end of the connecting rod 82, positioned in the cavity 800 of the shell and capable of extending out of the cavity 800 of the shell, and a second spring 820 sleeved on the connecting rod 82 and abutted against the locking part 81, wherein the teeth 810 are arranged at the edge of the locking part 81; the connecting rod 82 is telescopically arranged in the second through hole 860 and the connecting rod telescopic channel 859; wherein, the housing 80 may be a cuboid to mount other components and provide support, the housing 80 is located at the second end of the connecting rod 82, and the cavity 800 of the housing penetrates through the housing 80; the first elastic locking device further comprises: the fifth spring 84 is positioned in the cavity 800 of the shell, and the fifth spring 84 plays a role of resetting, is arranged between the inner wall of the shell 80 and the locking part 81 and is sleeved on the connecting rod 82;

As shown in fig. 9, 10 and 11, by pressing the lower box 85, the lower box 85 moves upward, the inclined surface 851 moves upward, the sliding part 821 is moved toward the first spring 850, that is, toward the middle of the upper box 86 or the horizontal section, and is away from the vertical section 9, so that the connecting rod 82, the locking part 81 connected thereto, and the teeth 810 on the locking part 81 are moved toward the middle of the horizontal section, and are away from the vertical section 9, and the teeth 810 of the inner vertical section are thus moved away from the rack 90 on the outer vertical section 9, and are unlocked, and the inner vertical section can thus slide relative to the outer vertical section. Conversely, if the lower box 85 is released, i.e. the lower box 85 is in a free state or is not pressed by a human hand, under the restoring action of the first spring 850, the lower box 85 moves downwards, the inclined surface 851 moves downwards, the sliding part 821 is far away from the first spring 850, i.e. far away from the middle position of the upper box 86 or the transverse section, and is close to the vertical section 9, so that the connecting rod 82, the locking part 81 connected with the connecting rod and the teeth 810 on the locking part 81 are far away from the middle position of the transverse section, and are close to the vertical section 9, the teeth 810 of the inner vertical section are meshed with the racks 90 on the outer vertical section 9 to form locking, and the inner vertical section is fixed or locked relative to the outer vertical section. Thus, the telescopic ladder is locked and can not be compressed to ensure the use safety when the hand is in a release state, namely the lower box body 85 is in a free state or a state not pressed by the hand.

The upper case 86 and the lower case 85 may have a rectangular parallelepiped shape, the guides 855 may have a cylindrical shape, the number of the guides 855 is four, and the four guides 855 form four vertices of a rectangle; the telescopic connecting rod channel 859 is located between the two guide parts 855, so that the guide parts can realize the function of guiding sliding and can also pass through an inclined plane, and the telescopic connecting rod channel 859 also fully utilizes the three-dimensional space of the lower box body 85 through a space which is properly arranged, so that the space is compact, the volume of the first elastic locking device is reduced, and the installation, the manufacture and the operation are convenient.

The first elastic locking device further comprises: the pressing block 857 is connected with the lower box body 85 and extends out of the transverse section from the bottom of the lower box body 85, and the pressing block 857 extends out of the end cover 87 and the transverse section 7 and is exposed out of the bottom of the transverse section 7, so that the pressing and the operation are convenient.

Go up box body 86 and can be located the intermediate position of horizontal segment, for example be located the half of horizontal segment, every first elasticity locking device can include two connecting rods, locking portion and tooth, every lower box body 85 can include the inclined plane that two symmetries set up, two connecting rods, locking portion and tooth, can the symmetry set up in the both sides of last box body 86 with lower box body 85, or say, first elasticity locking device is about (using the direction of horizontal segment to be left and right, use the direction of vertical segment to be upper and lower) symmetry, and like this, can realize two vertical segments in a ladder section and relieve locking or locking simultaneously, realize two vertical segment synchronous sliding, be favorable to the stability and the balance of ladder section. Of course, only one side or one link, a locking portion, and teeth may be provided to perform one-side locking, but the stability and balance performance are inferior.

Further, the inner ladder section further comprises: the second locking device, as shown in fig. 13, 14, 15, 16 and 17, includes:

a blind hole 811 provided in the locking portion 81; the top end of the blind hole 811 is a closed end, and the bottom end is an open end;

a first limiting step for limiting the downward movement of the first sliding block 813 is arranged in the blind hole 811 to prevent the first sliding block 813 from being separated from the blind hole 811;

as shown in fig. 15, 16 and 17, a locking sleeve 83 is provided in the housing 80 below the locking portion 81 by a rivet or a screw; the shell 80 can be a cuboid and is provided with a top wall, a bottom wall and a left side wall, the right side of the shell 80 is provided with an opening for the locking part and the teeth to come in and go out, and the left side wall of the shell 80 is provided with a connecting hole for the connecting rod 82 to come in and go out; the locking sleeve 83 is, for example, a circular sleeve and is arranged on the bottom wall of the housing 80, and the bottom wall of the housing 80 is a flat plate shape and provides a suitable space for processing and installing the locking sleeve 83;

the locking sleeve 83 has a top opening 830 and a bottom opening; top opening 830 and bottom opening are circular, the open end of blind hole is circular, positioning column 8131 can be cylindrical, the diameter of top opening is larger than the outer diameter of positioning column 8131; the top opening 830 has a locking position in centered communication with the blind hole 811 and an unlocking position staggered from the blind hole 811;

fig. 15 shows the offset position of the top opening 830 and the blind hole 811 in alignment, at this time, the positioning post 8131 cannot fall into the top opening 830, and the locking portion 81 and the teeth 810 are not affected by the locking sleeve 83 and can move left and right;

FIG. 16 shows the position of top opening 830 aligned with blind hole 811, and positioning post 8131 aligned with top opening 830, positioning post 8131 being able to drop into top opening 830 by third spring 812;

fig. 17 shows the positioning post 8131 falling into the top opening 830, the locking portion 81 and the teeth 810 are locked and cannot move left and right under the influence of the locking sleeve 83;

a button 835 movably disposed in a bottom opening of the locking sleeve 83; a second limit step for limiting the upward movement of the button 835 is arranged at the top opening to prevent the button 835 from being separated from the locking sleeve 83, and the distance between the second limit step and the top of the top opening is greater than 0, so that the top opening has enough depth to accommodate the downward movement of the positioning column 8131; as shown in fig. 15, 16 and 17, button 835 is located at one end of link 82 near the teeth, i.e., at both ends of cross section 7;

the fourth spring 832 is tightly abutted between the limit clamping platform and the button 835 to ensure that the button 835 cannot easily move upwards without external force.

As shown in fig. 17, when the positioning column 8131 falls into the top opening 830, the positioning column 8131, the locking portion 81 and the teeth 810 are locked, and at this time, by pressing the button 835 upwards, the button 835 overcomes the elastic force of the fourth spring 832, and after rising to a predetermined position, the positioning column 8131 can be ejected out of the top opening 830, so that the locking portion 81 is unlocked, and the locking portion 81 and the teeth 810 approach the vertical section 9 and the rack 90 under the restoring action of the second spring 820 and return to the position shown in fig. 15, so that the teeth 810 lock the rack 90; therefore, the second locking device is an additional locking device on the basis of the first locking device, and not only is the locking safety better guaranteed, but also the adjustment flexibility is improved, and the height adjustment is controlled in time.

Under the condition that only the first elastic locking device is configured, the locking and adjusting process of the invention is as follows:

the pressing block 857 in the middle of the transverse section 7 on the inner side is pressed upwards, the lower box body 85 moves upwards, the inclined plane 851 moves upwards, the sliding part 821 is close to the first spring 850, namely, the sliding part is close to the middle position of the upper box body 86 or the transverse section and is far away from the vertical section 9, therefore, the connecting rod 82, the locking part 81 connected with the connecting rod and the tooth 810 on the locking part 81 are close to the middle position of the transverse section and are far away from the vertical section 9, the tooth 810 of the vertical section on the inner side is far away from the rack 90 on the vertical section 9 on the outer side, locking is released, and the vertical section on the inner side can slide relative to the vertical section on the outer side.

When the vertical section on the inner side slides to a required position relative to the vertical section on the outer side, the pressing block 857 is loosened, the lower box body 85 and the inclined plane 851 are under the restoring action of the spring and move downwards, the sliding part 821 is far away from the first spring 850 and approaches the vertical section 9, the connecting rod 82, the locking part 81 connected with the connecting rod and the tooth 810 on the locking part 81 are far away from the middle position of the transverse section and approach the vertical section 9, the tooth 810 of the vertical section on the inner side accordingly approaches the rack 90 on the vertical section 9 on the outer side and locking is recovered, and the vertical section on the inner side can be locked to a specified height relative to the vertical section on the outer side, so that position adjustment of multiple grades can be realized between two adjacent ladder sections, and continuous and uniform position adjustment can be realized.

The adjustment process can be completed by using the first elastic locking device, namely, the invention can complete the position adjustment of two adjacent ladder sections in multiple grades by only configuring the first elastic locking device, and can realize continuous and uniform position adjustment. Furthermore, in order to better complete adjustment and locking, the reliability of locking is improved, and a second elastic locking device is added. In the case of disposing the first elastic locking device and the second elastic locking device at the same time, as shown in fig. 15, after the two adjacent ladder sections are locked, the pressing block 857 is pressed, as shown in fig. 16 and 17, under the action of the first elastic locking device, the connecting rod 82, the locking portion 81 connected thereto and the teeth 810 on the locking portion 81 are moved closer to the middle position of the horizontal section and away from the vertical section 9, the teeth 810 of the inner vertical section are moved away from the rack 90 on the outer vertical section 9 to be unlocked, the inner vertical section is ready to slide relative to the outer vertical section, but limited by the positioning post 8131 being positioned at the top opening 830, and the inner vertical section cannot slide relative to the outer vertical section immediately. At this time, under the action of the second elastic locking device, the button 835 overcomes the elastic force of the fourth spring 832 by pressing the button 835 upward, and after the button 835 is lifted to a predetermined position, the positioning column 8131 can be pushed out of the top opening 830, so that the locking of the locking portion 81 is realized, and the locking portion 81 and the teeth 810 are close to the vertical section 9 and the rack 90 under the restoring action of the second spring 820, so that the locking of the teeth 810 on the rack 90 is realized. That is, the rack 90 is extended and retracted by the teeth 810 through two-stage locking. Two ladder sections need to be compressed, two locking steps need to be removed, and therefore the safety of the extension ladder is improved.

In the case of configuring the first elastic locking device and the second elastic locking device simultaneously, if only the pressing block 857 is pressed or the first elastic locking device is activated, the teeth 810 of the inner vertical section are far away from the rack 90 on the outer vertical section 9, and are unlocked, the inner vertical section can slide relative to the outer vertical section, and during the sliding of the inner vertical section relative to the outer vertical section, although the button 835 of the second elastic locking device is not pressed, the positioning column 8131 of the second elastic locking device can automatically fall into the top opening 830 under the action of the third spring 812, and is still in a locked state, and the inner vertical section cannot slide relative to the outer vertical section. Only when the pressing block 857 and the button 835 are pressed simultaneously, the two locks are released, the positioning column 8131 is separated from the limitation of the top opening 830, the teeth 810 of the inner vertical section are far away from the racks 90 on the outer vertical section 9, and the inner vertical section can slide relative to the outer vertical section.

In the process that the inner vertical section slides relative to the outer vertical section, the pressing block 857 is released, and if there is no external interference, the lower case 85 moves downward by the restoring force of the first spring 850, the slope 851 moves downward, the sliding part 821 moves away from the first spring 850, i.e., away from the middle of the upper box 86 or the cross section, near the vertical section 9, the connecting rod 82 and the locking portion 81 connected thereto and the teeth 810 on the locking portion 81, away from the middle of the cross section, near the vertical section 9, at the same time, the positioning post 8131 on the locking portion 81 moves laterally toward the top opening 830, when moving above the top opening 830, the positioning column 8131 can automatically fall into the top opening 830 under the action of the third spring 812, so as to realize automatic locking, the teeth 810 of the inner vertical section thus mesh with the toothed rack 90 on the outer vertical section 9, forming a locking, and the inner vertical section is thus fixed or locked relative to the outer vertical section.

Thus, the unlocking operation between the two ladder sections is realized by simultaneously pressing the pressing block 857 and the button 835, after the locking between the two ladder sections is released, the button 835 can be released, and the two ladder sections can continuously slide relatively. The locking operation is to release the pressing block 857. In the relative sliding process of the two ladder sections, the stretching and retracting are not influenced by the releasing button 835, if positioning or locking is required, the automatic locking can be realized by only releasing the pressing block 857 without operating the button 835, and the position between the two ladder sections can be positioned or the height can be adjusted to be accurately controlled.

In all ladder sections, the structure of each horizontal section can be the same, and in addition, the horizontal section of the ladder section in the outside can not establish first locking device and second locking device, because, the ladder section in the outside can't stretch out and draw back again, like this, can simplify the preparation of the ladder section in the outside.

Further, as shown in fig. 18, 19, 20, 21 and 22, each vertical section 9 does not adopt a cylindrical or sleeve-type structure, the sliding surface between two adjacent vertical sections 9 is not a circular surface or a ring surface, each vertical section 9 is a channel steel or an aluminum alloy, an aluminum metal or a bridge-cut aluminum with a rectangular main body, the sliding surface between two adjacent vertical sections 9 is open and not closed, the sliding surface between two adjacent vertical sections 9 is mainly a plane, the sliding surface between two adjacent vertical sections 9 is a fixed value away from the inner vertical section, the vertical section away from the outer vertical section is a fixed value, that is, the sliding surface is only located on the same side of the inner vertical section or on the outer vertical section, for example, the sliding surface between two adjacent vertical sections 9 is located on the right side of the inner vertical section or on the left side of the outer vertical section, which does not form a sleeve or a cylindrical structure, one side of the sliding surface is positioned on the left side of the vertical section on the inner side, and the other side of the sliding surface is positioned on the right side of the vertical section on the inner side; such setting can guarantee that every vertical section 9 is not closed structure, guarantees gliding smooth, under the flexible circumstances of multisection compromise, guarantees that the wall thickness of each vertical section 9 can have sufficient size, because, two adjacent vertical sections 9 are unilateral connection rather than closed or annular connection, therefore guarantee that whole extension ladder's whole thickness is less than the extension ladder of drum formula vertical section. The sum of the widths of the vertical sections of the inner ladder section and the vertical sections of the outer ladder section is equal to or more than 2 times of the width of each vertical section before and after the adjacent two vertical sections 9 stretch out and draw back or in a sliding and locking state.

Each vertical section 9 comprises: a first sliding surface 91 and a second sliding surface 92 which are parallel and both of which are flat; the first sliding surface and the second sliding surface each have two ends, a first end (upper end in fig. 20) and a second end (lower end in fig. 20), respectively; the first sliding surface is positioned on the inner side of the second sliding surface, and the second sliding surface of the inner vertical section is positioned on the inner side of the first sliding surface of the outer vertical section; the sliding surface formed between the outside vertical section and the inside vertical section includes: and a plane sliding pair or a plane sliding friction surface formed by the first sliding surface of the outer vertical section and the second sliding surface of the inner vertical section. The main structure of the vertical section is a rectangular section bar, a groove or a hook arranged at the corner is arranged in an auxiliary mode, the friction between two rectangular planes is mainly between the vertical section at the outer side and the vertical section at the inner side, and the friction is not the annular friction or the closed friction surface of a traditional cylinder or a sleeve. In addition, the height of the ladder of the invention can be much smaller than that of the traditional cylinder or telescopic structure after the ladder is compressed or folded, and the ladder is more convenient to carry.

Two adjacent vertical sections of the present invention can adopt various open type section bar structures which can be mutually matched, for example, one of the forms is as follows: the section structure with rectangular section as main, every vertical section still includes: a first mounting surface 93 connected to a first end of the first sliding surface and a first end of the second sliding surface, a second mounting surface 94 connected to a second end of the second sliding surface and a second end of the second sliding surface;

the first sliding surface, the second sliding surface, the first mounting surface and the second mounting surface form a parallelogram and four intersection angles respectively positioned in four quadrants; the inside of this parallelogram can be the cavity to reduce weight, four crossing angles are respectively: a first intersection angle M positioned in a first quadrant, a second intersection angle N positioned in a second quadrant, a third intersection angle P positioned in a third quadrant and a fourth intersection angle Q positioned in a fourth quadrant;

a first hook 95 is arranged at the first intersection angle; the first hook includes: a first vertical edge 951 connected and extending from the first mounting surface 93, a first transverse edge 952 connected to the first vertical edge, and a second vertical edge 953 connected to the first transverse edge, the first vertical edge being parallel to the second vertical edge, the first vertical edge being longer than the second vertical edge, and the first transverse edge enclosing a first end of the first vertical edge and a first end of the second vertical edge; the first vertical edge is arranged close to the first sliding surface and extends towards the direction far away from the second mounting surface, and the outer side of the second vertical edge is flush with the first sliding surface; the first vertical edge 951, the second vertical edge 953 and the first transverse edge 952 form a first L-shaped slide rail;

Above-mentioned first L type spout forms interlock formula sliding construction with first L type slide rail, provides the direction for sliding, is favorable to the gliding stability between two vertical sections. Each vertical section can be formed into a hollow section structure with a rectangular main body by the first sliding surface, the second sliding surface, the first mounting surface and the second mounting surface, and four corners are respectively provided with a clamping hook or a clamping groove, as shown in fig. 20, each vertical section can be arranged in an up-down symmetrical mode, namely, the horizontal section of each vertical section is arranged in a front-back symmetrical mode, so that the vertical section is convenient to manufacture and is balanced in stress with each vertical section.

Further, in the above-mentioned case,

the first hook 95 further includes: a fifth transverse edge 954 connecting the first vertical edges and a fifth vertical edge 955 connecting the fifth transverse edge, the fifth transverse edge being parallel to and extending in the same direction as the first transverse edge, the fifth vertical edge being parallel to and extending in the same direction as the second vertical edge; the fifth transverse edge and the fifth vertical edge form a second L-shaped sliding rail; the second L-shaped slide rail is positioned between the first L-shaped slide rail and the first mounting surface, and the fifth vertical edge is flush with the first sliding surface;

second card slot 96 also includes: a sixth transverse side 965 connected to the third vertical side and extending in the same direction as the third transverse side, a sixth vertical side 966 connected to the sixth transverse side and extending in the same direction as the fourth vertical side, and a second L-shaped sliding groove 968 formed by the sixth transverse side and the sixth vertical side; the bottom surface of the sixth transverse edge is flush with the top surface of the first mounting surface;

The second L-shaped sliding groove and the second L-shaped sliding rail form an occlusion type sliding structure, so that the stability of sliding between the two vertical sections is improved, the shaking and friction between the two vertical sections are reduced, and the two vertical sections cannot be easily separated in the sliding process.

Further, in the above-mentioned case,

the second card slot further includes: a sloping edge 969 extending obliquely from the third transverse edge 962 in a direction away from the third vertical edge 961, wherein a trapezoidal limiting groove 9690 is formed between the sloping edge 969 and the fourth vertical edge 964 and the sixth vertical edge 966, and the minimum width of the limiting groove 9690 is greater than the width of the first vertical edge 951. The spacing groove 9690 of the vertical section 9 in the outside can be spacing the first vertical edge 951 of the vertical section 9 in the inside, so that most of the transverse edges and the vertical edges of the first clamping hook are spacing by the corresponding transverse edges and vertical edges of the first clamping groove, and the stability of the first clamping groove and the matching of the first clamping hook is improved. In addition, a sixth transverse edge 960 extending towards the third vertical edge 961 may be further disposed at the end of the oblique edge 969, and the oblique edge 969 and the sixth transverse edge 960 may form a hook shape to wrap the first vertical edge 951, thereby facilitating the stability of the sliding of the first vertical edge 951 of the inner transverse segment.

Further, in the above-mentioned case,

each vertical section further comprises: the rack comprises a mounting groove 910 recessed from the first sliding surface 91 to the second sliding surface 92 side, and a rack 90 mounted in the mounting groove 910, wherein the thickness of the rack is smaller than that of the mounting groove 910. Therefore, when two adjacent vertical sections slide relatively, position adjustment and locking can be achieved through the racks.

Further, in the above-mentioned case,

the mounting groove 910 is rectangular so as to mount the plate-shaped or strip-shaped rack 90; the mounting groove 910 includes: two bending sections 913 formed by bending the first sliding surface 91 to one side of the second sliding surface 92, and a groove bottom 911 connected between the two bending sections 913, wherein the two bending sections 913 and the groove bottom 911 form three rectangular sides;

each vertical section further comprises: the rack limiting plates 912 respectively extend from each bending section 913 to the bending section 913 on the opposite side, the rack limiting plates 912 are parallel to the first sliding surface 91 and the groove bottom 911, and the distance between the groove bottom 911 and the first sliding surface 91 is greater than the distance between the outer edge of the rack limiting plate 912 and the groove bottom 911, so that the installation of the rack does not affect the relative sliding of the two adjacent vertical sections. In addition, the second sliding surface 92 is recessed inwardly, i.e., recessed toward the first sliding surface 91, to form a groove having a width greater than the width of the rack, so that the second sliding surface 92 of the inner vertical section does not affect the rack of the outer vertical section during the sliding of the two vertical sections.

The cross section shapes and sizes of the vertical sections of the ladder sections can be completely the same, and the heights of the vertical sections can be completely the same, so that the sliding and the stretching between the vertical sections of the adjacent ladder sections can be realized, the modularization and the standardization of manufacturing and material selection are facilitated, the large-scale manufacturing is facilitated, and the cost is reduced.

The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. In order that the components of the present invention may be combined without conflict, it is intended that all equivalent changes and modifications made by those skilled in the art without departing from the spirit and principles of the present invention shall fall within the protection scope of the present invention.

Claims

1. An extension ladder, characterized in that it comprises at least:

the rack is meshed with the teeth.

2. The extension ladder of claim 1,

the rack is arranged on the inner side of the vertical section of the ladder section on the outer side, and the vertical section of the ladder section on the inner side is provided with a first through hole for the tooth and/or the first elastic device to enter and exit; the rack intersects with an extension line of the first through hole and faces the first through hole; the teeth and/or the first elastic device are/is arranged in the first through hole in a telescopic way; or the transverse section of the inner ladder section seals the two vertical sections of the inner ladder section, the bottom surface of the transverse section of the inner ladder section is lower than the bottom surfaces of the two vertical sections of the inner ladder section, a connecting hole for the tooth and/or the first elastic device to enter and exit is formed in the end part of the transverse section of the inner ladder section, and the rack is intersected with the extension line of the connecting hole and faces the connecting hole; the teeth and/or the first elastic device can be arranged in the connecting hole in a telescopic mode.

3. A telescopic ladder as claimed in claim 1, characterized in that the rack is flat or linear.

4. An extension ladder as claimed in claim 2,

the first elastic locking device specifically comprises: the box comprises an upper box body (86), a lower box body (85) which is arranged at the bottom of the upper box body (86) and can move up and down relative to the upper box body (86), and a first spring (850) which is arranged between the upper box body (86) and the lower box body (85); the two sides of the upper box body (86) are provided with second through holes (860), the top of the lower box body (85) is provided with a guide part (855) capable of sliding in the upper box body (86), the bottom of the lower box body (85) extends out of the bottom of the upper box body (86), and the top of the lower box body (85) is also provided with a connecting rod telescopic channel communicated with the second through holes (860); the top of the lower box body (85) is also provided with an inclined plane (851) which is connected with the guide part (855) and extends obliquely;

the first elastic locking device further comprises: the gear tooth structure comprises a shell (80), a cavity (800) of the shell, a connecting rod (82) extending into the shell and capable of moving in the cavity (800) of the shell, a sliding part (821) arranged at a first end of the connecting rod (82) and capable of sliding on an inclined plane (851), a locking part (81) arranged at a second end of the connecting rod (82), located in the cavity (800) of the shell and capable of extending out of the cavity (800) of the shell, and a second spring (820) sleeved on the connecting rod (82) and abutted against the locking part (81), wherein the gear tooth is arranged at the edge of the locking part (81); the connecting rod (82) is arranged in the second through hole (860) and the connecting rod telescopic channel in a telescopic mode; wherein the shell (80) is positioned at the second end of the connecting rod (82), and a cavity (800) of the shell penetrates through the shell (80); the first elastic locking device further comprises: the fifth spring (84) is positioned in the cavity (800) of the shell, and the fifth spring (84) is arranged between the inner wall of the shell (80) and the locking part (81) and sleeved on the connecting rod (82);

the transverse section is provided with a hollow structure for accommodating the upper box body (86), the shell (80) and the connecting rod (82), and a third through hole for the lower box body (85) to stretch or press the lower box body (85) is formed in the bottom of the transverse section.

5. The extension ladder of claim 4, wherein the inner ladder sections further comprise: a second locking device, the second locking device comprising:

a blind hole (811) provided in the locking portion (81); the top end of the blind hole (811) is a closed end, and the bottom end is an open end;

a first slide block (813) which is arranged in the blind hole (811) and can move up and down in the blind hole;

a first limiting step for limiting the downward movement of the first sliding block (813) is arranged in the blind hole (811);

a positioning column (8131) which is arranged at the bottom of the first sliding block (813) and can enter and exit from the opening end; the aperture of the positioning column (8131) is smaller than that of the first sliding block (813);

the third spring (812) is tightly propped between the closed end of the blind hole (811) and the first sliding block (813);

a locking sleeve (83) disposed in the housing (80) and located below the locking portion (81); the locking sleeve (83) has a top opening (830) and a bottom opening;

the caliber of the top opening is larger than that of the positioning column (8131); the top opening (830) is provided with a locking position which is in centering communication with the blind hole (811) and an unlocking position which is staggered with the blind hole (811);

a button (835) movably disposed in a bottom opening of the locking sleeve (83);

a second limiting step for limiting the upward movement of the button (835) is arranged at the top opening, and the distance between the second limiting step and the top of the top opening is more than 0;

and the fourth spring (832) is tightly propped between the limiting clamping table and the button (835).

6. The extension ladder of claim 1,

each vertical section comprises: a first sliding surface (91) and a second sliding surface (92) which are parallel, wherein the first sliding surface and the second sliding surface are both planes; the first sliding surface of each vertical section is positioned inside the second sliding surface of each vertical section;

the second sliding surface of the inner vertical section is positioned at the inner side of the first sliding surface of the outer vertical section; the sliding surface between the outside vertical section and the inside vertical section includes: and a plane sliding pair or a plane sliding friction surface formed by the first sliding surface of the outer vertical section and the second sliding surface of the inner vertical section.

7. An extension ladder as claimed in claim 6,

the first sliding surface and the second sliding surface are respectively provided with two ends which are respectively a first end and a second end; each vertical section further comprises: a first mounting surface (93) connected to a first end of the first sliding surface and a first end of the second sliding surface, and a second mounting surface (94) connected to a second end of the second sliding surface and a second end of the second sliding surface;

the first sliding surface, the second sliding surface, the first mounting surface and the first mounting surface form a parallelogram and four intersection angles respectively positioned in four quadrants; the four intersection angles are respectively: a first intersection angle M positioned in a first quadrant, a second intersection angle N positioned in a second quadrant, a third intersection angle P positioned in a third quadrant and a fourth intersection angle Q positioned in a fourth quadrant;

a first hook (95) is arranged at the first intersection angle; the first hook includes: the device comprises a first vertical edge (951), a first transverse edge (952) connected with the first vertical edge, and a second vertical edge (953) connected with the first transverse edge, wherein the first vertical edge is parallel to the second vertical edge, the length of the first vertical edge is greater than that of the second vertical edge, and the first transverse edge seals a first end of the first vertical edge and a first end of the second vertical edge; the first vertical edge is arranged close to the first sliding surface and extends towards the direction far away from the second mounting surface, and the outer side of the second vertical edge is flush with the first sliding surface; the first vertical edge (951), the second vertical edge (953) and the first transverse edge (952) form a first L-shaped sliding rail;

second angle of intersection department is equipped with second draw-in groove (96), and the second draw-in groove includes: a third vertical edge (961), a third transverse edge (962) connecting the third vertical edge; the third perpendicular limit is located the nodical and with first perpendicular limit syntropy extension of first glide plane and first installation face, the second draw-in groove still includes: a fourth transverse edge (963) connected with the third vertical edge and extending opposite to the first transverse edge, and a fourth vertical edge (964) connected with the fourth transverse edge and extending in the same direction with the third vertical edge, wherein the third transverse edge (962), the third vertical edge (961), the fourth vertical edge (964) and the fourth transverse edge (963) form a first L-shaped sliding chute (967); the first L-shaped sliding groove is matched with the first L-shaped sliding rail in shape.

8. An extension ladder as claimed in claim 7,

the first hook further includes: a fifth transverse edge (954) connecting the first vertical edges and a fifth vertical edge (955) connecting the fifth transverse edge, the fifth transverse edge being parallel to and extending in the same direction as the first transverse edge, the fifth vertical edge being parallel to and extending in the same direction as the second vertical edge; the fifth transverse edge and the fifth vertical edge form a second L-shaped sliding rail; the second L-shaped slide rail is positioned between the first L-shaped slide rail and the first mounting surface, and the fifth vertical edge is flush with the first sliding surface;

the second card slot further includes: a sixth transverse side (965) connected with the third vertical side and extending in the same direction as the third transverse side, a sixth vertical side (966) connected with the sixth transverse side and extending in the same direction as the fourth vertical side, and a second L-shaped sliding groove (968) is formed by the sixth transverse side and the sixth vertical side; the bottom surface of the sixth transverse edge is flush with the top surface of the first mounting surface;

9. An extension ladder as claimed in claim 7,

each vertical section further comprises: the sliding surface comprises a mounting groove (910) which is recessed from the first sliding surface (91) to the second sliding surface (92) side, and a rack (90) which is mounted in the mounting groove (910), wherein the thickness of the rack is smaller than that of the mounting groove (910).

10. The extension ladder of claim 9,

the mounting groove (910) is rectangular, and the mounting groove (910) includes: the sliding door comprises two bending sections (913) bent from the first sliding surface (91) to one side of the second sliding surface (92) and a groove bottom (911) connected between the two bending sections (913), wherein the two bending sections (913) and the groove bottom (911) form three rectangular sides;

each vertical section further comprises: the rack limiting plate (912) extends from each bending section (913) to the opposite bending section (913), the rack limiting plate (912) is parallel to the first sliding surface (91) and the groove bottom (911), and the distance between the groove bottom (911) and the first sliding surface (91) is larger than the distance between the outer edge of the rack limiting plate (912) and the groove bottom (911).