EXTENSION LADDER WITH IMPROVED STRUCTURE
BACKGROUND OF THE INVENTION
Field of the invention The present invention relates to an extension ladder, and more particularly to an extension ladder apparatus, which is assembled easily and securely, providing superior safety.
Description of the Prior Art Accordingly, stepladders have become a requisite tool for casual use. For example, climbing tools such as a ladder or scaffolding enable people to readily process construction or obtain the objects at a high place.
A conventional stepladder 800, as shown in FIG. 1, is assembled by two ladder sections having a footpad respectively to prevent slippage, and is provided with parallel spaced step portions therein. The stepladder appears as an A-frame ladder during usage.
Stepladders are typically large and bulky therefore, it is uneasy and inconvenient to carry them. Moreover, the storage of a folded stepladder may occupy large space, which makes the use of a stepladder inflexible.
Accordingly, the present invention has been invented to solve the above-mentioned problems occurred in the prior art.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an extension ladder with improved structure, which is composed of multi-segment ladder sections, connection kits, locking mechanism, and transverse step portions, providing ease and convenience to fold and take along, store, or unfold and use.
In the extension ladder apparatus according to the present invention, the connection kits and hollow rungs are locked in place, and then stuck and fastened. This prevents these components from loose and disattachment, which serves as another object of the present invention.
The extension ladder apparatus according to the present invention, in which the locking mechanism provided inside the connection kits are wrapped by transverse step portions, and can avoid the damage of rust, which serves as further object of the present invention.
The detailed structure, application principle, function, and effects of the present invention will be more apparent from the following descriptions taken in conjunction with the accompanying drawings.
FIG. 1 is a three-dimensional view of the conventional extension ladder;
FIG. 2 is a three-dimensional view of the present S invention;
FIG. 3 is a three-dimensional view showing the folding and unfolding of the push rod in the present invention;
FIG. 4A is a three-dimensional exploded view showing the ladder section and transverse step portion in the present invention;
FIG. 4B is a three-dimensional assembly view showing the partial construction of the present invention;
FIG. 5 is a three-dimensional assembly view showing the ladder section and transverse step portion in the present invention;
FIG. 6 is a sectional view showing the assembly of the ladder section and transverse step portion in the present invention; and FIG. 7 is a sectional view of the embodiment in the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The extension ladder with improved structure in the present invention, as shown in FIG. 2, wherein the extension ladder 1 is foldable, or unfoldable as shown in FIG. 3, includes a plurality of ladder sections 2, connection kits 3, and transverse step portions 5. The stepladder appears as a rising , S ladder when it is unfolded and used, and can be folded by fitting the ladder sections with different calibers one another.
Referring to FIG. 4 and 5, each ladder section 2 fits each other by providing similar-shaped but smaller internal ladder sections 2a. Said cannular-shaped ladder section 2 is provided with a snap-fit hole 21 and a orientation hole 22 on its upper end, and provided with a through hole 23 and opening 24 on its lower end. Also, a blocking ring 25 is provided on the upper end of said through hole 23 at proper height.
~ The connection kit 3 has a ringlike covering part 31 and a pivotal joint 32. Said ringlike covering part 31 is horizontally provided on the upper end of the ladder section, and affixed to the ladder section by fastening'a screw therein.
A plurality of orientation tenons 34 are provided on the inside of said connection kit for engaging with the snap-fit hole 21 of said ladder section, so that the connection kit can be assembled with the ladder section quickly. Also, the inside wall of said connection kit is provided with an adhesive channel 35, wherein the adhesive are infused into the adhesive-infusing hole 36 on its one end so that the connection kit can be firmly adhered to the ladder section 2. Moreover, a via hole 30 is provided on the connection kit for interconnecting with the internal channel 3? of said pivotal joint 32.
S Said pivotal joint 32 is integrally molded with the ringlike covering part 31, and its internal channel 37 can be passed through. A groove 38 is provided in the end of said channel 37 for loading the locking mechanism 4.
Said locking mechanism 4, as shown in the figure, includes a locking gate 41, a locking bar 42, a spring 43, and a turning rod 44; two wings of said locking gate 41 is provided with a plug plate 411 and 412 respectively, and its center is provided with a sleeve 413. When the plug plate 411 and 412 on said locking gate are inserted into the groove 38 of the pivotal joint, the sleeve 413 is directly in the channel 37 of said pivotal joint. The inside of said sleeve 413 is provided with a spring 43 and a locking bar 42, while one end of said locking bar is firmly against the spring 43 and the other end directly faces the via hole 30 of ringlike covering part and the orientation hole 22 of said ladder section. An axle center 421 with a smaller caliber is provided in the middle of said locking bar, so that the turning rod 44 can be inserted therein and twisted. The tenons 441 on two bottom sides of said turning rod 44 are provided into the predetermined groove of said pivotal joint for orientation. Also, a fork-shaped wiper blade 442 on one end of said turning rod is inserted into said axle center 421 to control the onward and backward movement of said locking bar 42.
When the locking mechanism 4 is installed in the pivotal joint 32, the transverse step portion 5 is then provided onto the outside of said pivotal joint 32. The side wall end of said transverse step portion 5 is provided with a cross hole 51 for the turning rod 44 to extend out forwardly for the twist and control.
In addition, the lower end of the hollow rung 21 is provided with a sleeve-shaped buffering device 6. The upper end of said buffering device, by means of a hooked tip 61 provided thereon, is affixed to the opening 24 of said ladder section 2. The lower-end outside of said buffering device is provided with an elastic seal ring 62 to increase friction when it contacts with the inside of said rung and reduce noise. Also, as shown in FIG. 6, the internal part of said buffering device is provided with a mylar 63 with its surface having a hole, which allows airs to enter the cavity of said mylar 63 when the buffering device 6 moves upward and downward, and thus enhances the cushion effect.
When the assembling has been completed, as shown in the figure, the bottom of the ladder section 2 is provided with a buffering device 6 and an elastic seal ring 62 to increase the friction between the ladder section and the inside wall of internal ladder section, so that the purpose of slowing down the descending can be achieved. Also, the connection kit and the upper end of said ladder section are provided with adhesive channel 35 to infuse the adhesive therein, so that the connection kit and the ladder section can be adhered to each other. Accordingly, the present extension ladder is assembled integrally and securely: Moreover, the provided locking mechani$m 4 is fully covered by the connection kit 3 and the transverse step portion 5, which not only makes it easy and convenient to control the locking mechanism, but also prevents the damage caused by any foreign object.
As shown in FIG. 6, when the internal ladder section 2a and ladder section 2 are extended to use relatively, the blocking ring 2a1 having a larger caliber on the outside of said internal ladder section 2a is firmly against the inwardly protruding ring 311 of said connection kit in the external ladder section. Meanwhile, the through hole 2a2 on the lower end of said internal ladder section 2a is directly located in a route having the orientation hole 22 of said external ladder section, via hole 30 of said connection kit, and locking bar 42 a, which enables the locking bar 42 to be inserted in the fixed position smoothly when it is moved forward.
In the following description and drawings, different reference numerals are used to designate different components.
When a stepladder is folded, as shown in FIG. 7, the first-level turning rod 71 is twisted backward to force the locking bar 72 to withdraw from the through hole of second ladder section 73. Then, the second ladder section 73 falls downward along with the second transverse step portion 74 owing to a lack of any obstruction. Similarly, if the turning rod 75 is twisted backward, the locking rod 77 shall be forced to withdraw from the through hole. Then, the third ladder section 78 together with the third transverse step portion 79 falls down consequently. On the analogy of this, all rung sections and step portions can be folded quickly.
Accordingly, the extension ladder with improved structure in the present invention are integrally assembled securely by providing a snap-fit hole 21, orientation tenon 34, and blocking ring 25 between the connection kit 3 and ladder section 2 for quick and correct orientation. Also, the ladder assembly can be securely by providing with the adhesive channel 35. Furthermore, the locking mechanism 4 is provided on the connection kit 3 for making the assembling more convenient, the control of the ladder easier, and prolonging ladder life.
As described above, the extension ladder apparatus in the present invention certainly enhances appliance safety, and makes folding and using quick.and convenient, which can improve the deficiencies of conventional ladders. Also, the present invention has not yet opened to public, it is then complied with the conditions of allowable patents.
Although the above-mentioned embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.