Collapsible ladder

Abstract

A collapsible ladder includes two vertical stiles with rungs disposed therebetween. Each stile is formed by a plurality of telescopically collapsible columns. Each collapsible column has a bottom opening, an inner wall and a cover to cover the bottom opening. The cover has a small cylindrical portion and a large cylindrical portion with a peripheral surface located under the small cylindrical portion. The small cylindrical portion is inserted into the bottom opening of a column The large cylindrical portion is exposed outside of the column and inserted inside of a next lower column. A sealing ring is disposed inside a annular groove and touches the inner wall of the next lower column when the stile is extending or collapsing. One or more air ducts are provided in the cover. A first air opening iarranged above the large cylindrical portion in correspondence with an opening in a lower wall part of the column.

Claims

1. A collapsible ladder comprising: two vertical stiles with a plurality of rungs disposed between the two vertical stiles, a stile of the two vertical stiles being formed by a plurality of telescopically collapsible columns; wherein one or more of the plurality of telescopically collapsible columns has a bottom opening and an inner wall; a cover configured to be received at the bottom opening of a respective column of the one or more of the plurality of telescopically collapsible columns to cover the bottom opening; wherein the cover has a small cylindrical portion and a large cylindrical portion with a peripheral surface located under the small cylindrical portion; the small cylindrical portion is inserted into the bottom opening of the respective column and is positioned inside the respective column, while the large cylindrical portion is exposed outside of the respective column and inserted inside of a next lower column of the one or more of said plurality of telescopically collapsible columns; an annular groove is formed on the peripheral surface of the large cylindrical portion; a sealing ring is disposed inside the annular groove, with the sealing ring touching the inner wall of the next lower column when the stile is extending or collapsing, said sealing ring forming a frictional seal for the next lower column and dividing the next lower column into an upper part above the sealing ring and a lower part below the sealing ring; and wherein one or more air ducts are provided in the cover, each air duct having a first air opening and a second air opening, the first air opening disposed above the large cylindrical portion of the cover and within an opening defined between a lower wall part of the respective column receiving the cover and the interior of the upper part of the next lower column, whereby the first air opening faces the inside or the interior of the upper part of the next lower column, and the second air opening facing a bottom part of the cover and the inside or the interior of the lower part of the next lower column, thereby enabling air to exit from the upper part to the lower part of the next lower column.

2. A collapsible ladder according to claim 1, wherein an elastic or elastomeric seal or film is provided below the bottom part of the cover and secured to the bottom part of the cover, said seal extending beneath the second air openings facing the bottom part of the cover.

3. A collapsible ladder according to claim 2, wherein the elastic or elastomeric seal or film is secured to the bottom part of the cover and extending beneath the second air openings so as to cover the second air openings.

4. A collapsible ladder according to claim 2, wherein the elastic or elastomeric seal or film is secured to the bottom part of the cover for sealing the second air openings when the stile is collapsed by having the upper column being collapsed into the next lower column, and for unsealing the second air openings when the stile is extended by extending the upper column outwards or upwards from the next lower column.

5. A collapsible ladder according to claim 1, wherein an auxiliary sealing ring is disposed between the bottom of the small cylindrical portion of the cover and the inner wall of the column.

6. A collapsible ladder according to claim 1, wherein at least one protruding ring part is formed in each or at least part of the plurality of telescopically collapsible columns, wherein the outer diameter of the at least one protruding ring part is larger than the outer diameter of a column in which the at least one protruding protruding ring part is formed, and smaller than the inner diameter of a next lower column.

7. A collapsible ladder according to claim 6, wherein at least two protruding ring parts of the at least one protruding part are formed in each or at least part of the plurality of telescopically collapsible columns.

8. A collapsible ladder according to claim 6, wherein the one or more of said plurality of telescopically columns having the at least one protruding ring part have a locking hole for receiving a locking pin, and wherein a first protruding ring part of the at least one protruding ring part is formed above said locking hole.

9. A collapsible ladder according to claim 8, wherein a second protruding ring part of the at least one protruding ring part is formed below said locking hole.

10. A collapsible ladder according to claim 6, wherein the at least one protruding ring part is formed in a column by a rolling process.

11. A collapsible ladder according to claim 1, wherein one or more of said plurality of columns have a locking hole for receiving a locking pin, and wherein the bottom cover has a sloped nose or protruding part extending from the bottom of the cover and arranged so as to push a locking pin received in a locking hole of the next lower column.

12. The collapsible ladder according to claim 2, wherein a centre part of the elastic or elastomeric seal or film is secured to a centre part of the bottom part of the cover.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of an extendable ladder in accordance with an embodiment of the present disclosure when the columns are extended,

(2) FIG. 2a is a sectional perspective view of parts of an extendable ladder in accordance with an embodiment of the present disclosure when the columns are extending,

(3) FIG. 2b is a sectional perspective view of the ladder parts illustrated in FIG. 2a when the columns are collapsing, and

(4) FIG. 3 illustrates the arrangement of a cover at the bottom of a column according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

(5) FIGS. 1 to 3 show preferred embodiments of the present disclosure. The extendable ladder of FIG. 1 comprises two vertical stiles with a plurality of rungs 6 disposed between two stiles, each stile being formed by a plurality of telescopically collapsible columns 1a, 1b, each column 1a, 1b being connected to the corresponding rung 6 via a connecting sleeve 7; a plug or locking pin is disposed inside the connecting sleeve 7, which can move horizontally and transversely with respect to the connection sleeve 7 and be exposed outside to lock the column 1a together with the next lower column 1b; a spring disposed inside the connection sleeve 7, which can keep the plug pin in the trend of being exposed outside; a locking hole 10 is provided in the column 1a, 1b for receiving the plug or locking pin, and a push button 8 or release lever may be provided which can drive the plug pin to move transversely to lock or unlock a column 1a, 1b into a next lower column 1a, 1b.

(6) The foregoing shows the conventional structure of an extendable ladder. According to an embodiment of the present disclosure and illustrated in FIGS. 1, 2a, 2b and 3, there is provided an extendable ladder for which: each or at least part of the collapsible columns 1a, 1b, 21, 22 has a bottom opening and an inner wall and receives a cover 23 at the bottom opening to cover the bottom opening; the cover 23 has a small cylindrical portion 24 and a large cylindrical portion 25 with a peripheral surface located under the small cylindrical portion 24; the small cylindrical portion 24 is inserted into the bottom opening of a column 21 and is positioned inside the column 21, while the large cylindrical portion is exposed outside of the column and inserted inside of a next lower column 22; an annular groove 26 is formed on the peripheral surface of the large cylindrical portion 25; a sealing ring 27 is disposed inside the annular groove 26, with the sealing ring 27 touching the inner wall of the next lower column 22 when the stile is extending or collapsing, whereby the sealing ring 27 forms a frictional seal for the next lower column 22 and dividing the next lower column 22 into an upper part 28 above the sealing ring and a lower part below the sealing ring 29; one or more, such as two air ducts 30a, 30b are provided in the cover 23, where each air duct 30a, 30b has a first air opening 31 and a second air opening 32, with the first air opening 31 arranged above the large cylindrical portion 25 and in correspondence with an opening 36 in a lower wall part of the column 21 receiving the cover 23, whereby the first air opening 31 faces the inside or the interior of the upper part 28 of the next lower column 22, and with the second air opening 32 facing a bottom part of the cover 23 and the inside or the interior of the lower part 29 of the next lower column 22, thereby enabling air to exit from the upper part 28 to the lower part 29 of the next lower column 22.

(7) It is preferred that an elastic or elastomeric seal or film 34 is provided at the bottom of the cover 23 and secured to a bottom part of the cover, where the seal 34 extends beneath the second air openings 32 facing the bottom of the cover 23. The elastic or elastomeric seal or film 34 may be secured to the bottom part of the cover 23 and extend beneath the second air openings 32 so as to possible cover the second air openings 32. The elastic or elastomeric seal or film 34 is secured to the bottom part of the cover for sealing the second air openings 32 when the stile is collapsed by having the upper column 21 being collapsed into the next lower column 22, and for unsealing the second air openings 32 when the stile is extended by extending the upper column 21 outwards or upwards from the next lower column 22. An auxiliary sealing ring 35 may be disposed between the bottom of the small cylindrical portion 24 of the cover 23 and the inner wall of the column 21.

(8) For ladders of the present invention having columns 21 provided with a bottom cover 23, then FIG. 2a shows a sectional cut through view of parts of the extendable ladder, when the columns 1a, 1b, 21, 22 are extending, and FIG. 2b shows the same cut through view when the columns 1a, 1b, 21, 22 are collapsing. FIG. 3 is not a cut through view of the bottom cover 23, but illustrates the arrangement of the cover 23 at the bottom of a column 1a, 21. The bottom cover of FIG. 3 is also provided with a sloped nose or protruding part 37 extending from the bottom of the cover 23 and arranged so as to push a locking pin received in a locking hole 10 of the next lower column 1b, 22.

(9) During the collapsing of the upper column 21 into the next lower column 22, the seal 34 is moved slides upward relatively to the bottom of the cover 23, thereby closing the second air openings 32 of the air ducts 30a, 30b, and air is not passed through the air ducts 30a, 30b, so the collapsing of the column 21 is slowed down due to resistance of air inside the closed spaced at the interior 29 of the next lower column 22. Due to the slowed collapsing, a person may have enough reaction time to withdraw his/her fingers in time even through the fingers are just in an inappropriate position. In addition, since the speed of the collapsing of the ladder is slowed down, the force applied to the fingers is quite small even if the fingers are crushed. Therefore, the purposes of preventing finger injury and eliminating potential safety hazards are achieved. In addition, when the columns move upward while the extendable ladder is extending for use, the seal 34 is moved downwards thereby opening the second air openings 32, and air can exit without resistance through the air ducts 30a, 30b from the upper part 28 to the lower part 29 of the next lower column 22.

(10) The present disclosure also covers embodiments of a collapsible ladder, wherein at least one protruding ring part 9a, 9b is formed in each or at least part of the collapsible columns 1a, 1b, 21, 22, wherein the outer diameter of the ring part 9a, 9b is larger than the outer diameter of the column 1a, 1b, 21, 22 in which the ring part 9a, 9b is formed, and smaller than the inner diameter of a next lower column. This is illustrated in FIG. 1 where two protruding ring parts 9a, 9b are shown on the next lower column 1b. A lowermost protruding ring part 9b is also shown on the inner column 21 in FIG. 3. It is preferred that at least part of the collapsible columns 1a, 1b, 21 provided with one or more protruding ring parts 9a, 9b have a bottom opening and an inner wall and receives a cover 23 at the bottom opening to cover the bottom opening. The present invention also covers embodiments for which the outer diameter of the cover 23 is smaller than the outer diameter of the protruding ring part 9a, 9b. The cover 23 may have a small cylindrical portion 24 and a large cylindrical portion 25 with a peripheral surface located under the small cylindrical portion 24, and the small cylindrical portion may be inserted into the bottom opening of a column 21 and positioned inside the column, while the large cylindrical portion may be exposed outside of the column and inserted inside of a next lower column 22. Here, an auxiliary sealing ring 35 may be disposed between the bottom of the small cylindrical portion 24 of the cover and the inner wall of the column 21. One or more of the collapsible columns 1a, 1b, 21, 22 having a protruding ring part 9a, 9b have a locking hole 10 for receiving a locking pin, and it is preferred that a first protruding ring part 9a is formed above the locking hole 10. It is also preferred that a second protruding ring part 9b is formed below the locking hole 10, and the second protruding ring part 9b may be arranged with a distance to the locking hole 10 being larger than the distance to the bottom of the column 1b. The column 1a, 1b may be made of Aluminium and the protruding ring part(s) 9a, 9b may be formed in the Aluminium by a rolling process.

(11) The present disclosure also covers embodiments of a collapsible ladder wherein one or more columns 1a, 1b have a locking hole 10 for receiving a locking pin, and wherein the bottom cover 23 has a sloped nose or protruding part 37 extending from the bottom of the cover 23 and arranged so as to push a locking pin received in a locking hole of the next lower column. Such a sloped nose or protruding ring part 37 is shown at the cover 23 of FIG. 3.

(12) By having one or more, such as two, protruding rings parts 9a, 9b formed in the collapsible columns 1a, 1b there is provided a solution for a collapsible ladder having guiding parts for guiding the a first upper column into a next lower, second column, which guiding part is not easily worn out.