Domestic hydraulic step ladder characterized by steplessly variable height of steps and platforms

Abstract

The invention relates to a domestic hydraulic step ladder, comprising a large-area table-board platform for standing and working at levels at different heights from the floor, said platform being divided from the middle into two halves, each half being mounted on two multi-stage telescopic hydraulic cylinders, all of the four telescopic hydraulic cylinders are carried on a common base and are connected by means of a three-position hydraulic valve to a small conventional air preloading hydropneumatic accumulator equipped with a mini-air pump for air preloading control, in order to manually climb the step ladders, the four telescopic hydraulic cylinders are connected by means of a three-position hydraulic valve to the small conventional air preloading hydropneumatic accumulator, and the four telescopic hydraulic cylinders are connected by means of a three-position hydraulic valve to the small conventional air preloading hydropneumatic accumulator. When the two halves are at the same level at the lowest point of the step ladder, a person climbs up the platform by placing one foot on each of the two platform halves, then operating the three-position hydraulic valve, and by maintaining a suitable posture on the platform, effecting raising / standing / lowering of the platform.

Description

Technical Field

[0001] The present invention relates to a step ladder commonly used in domestic interiors for climbing by an individual to reach a level from which the individual can reach and work on a task horizontally up to the ceiling while standing on a provided platform.

[0002] The present invention falls within the category of step ladders, essentially because the user actually climbs steps formed by one or the other split half of a platform which, when not bearing a load, is in a position to automatically rise to a higher level and is raised relative to the other stationary, load-bearing platform half, and when the two platform halves are at the same level and locked in place, the user can reach any desired higher level and can comfortably stand with both feet at the same level on the wide modular platform to perform any task at the higher level. Background Art

[0003] Almost all existing and available step ladders have only one platform that is long and wide enough without any obstructions, at a fixed level, where a person can comfortably stand with both legs at the same level and position the body in any of the four directions to complete any necessary task. For example, a 3-foot step ladder has the above-mentioned platform type only at a fixed level of 3 feet, similarly, a 4-foot step ladder has the above-mentioned platform type at a fixed level of 4 feet, and so on. Even if some types of step ladders do not have narrower steps, but they are provided with wider steps, which are almost the same size as the provided platform (patent US2017 / 032813125A1) and are mistaken for additional platforms, they do not function as platforms as explained earlier in this paragraph, because these steps must be staggered one after another (to avoid the step ladder occupying a large floor area).

[0004] Thus, when a person stands on a lower wide step, the next higher wide step will create an obstacle, and only the uppermost step / platform will function as a true platform as explicitly mentioned above.

[0005] It can be further explained here that a good functional platform will have a large area on which the user can stand without any hindrance, which provides the user with a higher degree of safety and stability when working above the ground, whereby there is less worry or less concern about falling from the step ladder and getting injured, because being on a platform that more closely simulates working on the ground, the risk of falling and getting injured there is no more or less than what the user normally experiences in daily activities on the ground.

[0006] Therefore, the problem we have with all the existing and available stair ladders is that they fail to serve the purpose most of the time because people come to different heights and they need to do different tasks at different times and at different heights which requires the platforms to be at different heights, because of this, in all the currently existing stair ladders, in 95% of the cases, the user has to stand dangerously on the "rungs" of these stair ladders to perform various tasks and also considering people of different ages and different body shapes, they may not only find it difficult but also risk injuring themselves to lift their legs 8 to 12 inches and climb up the currently existing and available stair ladders.

[0007] It has long been known to use hydro-pneumatic accumulators, in which a hydraulic fluid is kept under pressure by means of compressed air which acts on a membrane separating the hydraulic fluid and compressed air sections, and the pressurized hydraulic fluid is used through a hydraulic valve to actuate an extendable and retractable "single" piston in a hydraulic cylinder.

[0008] The above mentioned arrangement is adopted in a number of patents associated with height adjustable dentist chairs / stools and the like, as shown by the list of patent examples given below;

[0009] US2,218,963 (1940), US3,147,946 (1964),

[0010] US 3,339,873 (1967),

[0011] US3,711,054 (1973), US4,220,307 (1980),

[0012] US6,494,124 (2002).

[0013] In all of the above, the height adjustment range is limited and only a “single” large-size piston-cylinder combination is used.

[0014] The main reason why a "multi-stage hydraulic telescopic arrangement" has never been used in conjunction with a hydropneumatic accumulator for applications similar to the above mentioned is that no arrangement has hitherto been available which ensures a strictly progressive extension and retraction of the different stages, especially when the piston and cylinder diameters are small.

[0015] There are some patents covering progressive extension and retraction in the case of large diameter telescopic cylinders (these telescopic cylinders are operated by a hydraulic pump that supplies hydraulic fluid at very high pressure and volume) and contain complex valve mechanisms (occupying a large area inside the cylinder), such as US3,259,027 (1966), US5,584,645 (1996).

[0016] Therefore, based on the above situation, there is an urgent need for a novel step ladder. Summary of the invention

[0017] The object of the present invention is to create a new advanced domestic step ladder which solves and overcomes all the disadvantages and all the problems (explained above) faced by every domestic step ladder user.

[0018] Another object of the invention is to create a domestic step ladder that meets all requirements with a comfortable and functional platform, having a built-in arrangement where the user, while on the step ladder, decides the height of the steps and decides at which level he or she wants to be on the comfortable and functional platform to perform the specific task at hand and keep both legs at the same level:

[0019] In addition to the above, another major advantage of the present invention is that it has a 50% smaller footprint than all existing and available home step ladder options, allowing it to be used more efficiently in confined spaces.

[0020] Another advantage of the present invention is the safety factor, because the user's center of gravity shifts only a small amount when climbing when compared to all existing domestic step ladders, because climbing is achieved by side steps rather than front steps as in currently available step ladders.

[0021] Another object of the present invention is that it will be the first solution to date to use the hydro-pneumatic accumulator device mentioned above to operate a multi-stage piston-cylinder combination, which is commonly known as a "multi-stage telescopic hydraulic cylinder arrangement structure", although in this case the diameter of the piston and cylinder is relatively small, but has multiple stages.

[0022] Another object of the present invention is that it employs for the first time the hydro-pneumatic accumulator explained above accompanied by a multi-stage telescopic hydraulic arrangement which operates on the basis of a low pressure and low volume hydraulic section, the multi-stage telescopic hydraulic arrangement using small piston and cylinder diameters and still ensuring strictly progressive extension and retraction through a unique sliding valve arrangement.

[0023] Another object of the present invention is that it utilizes the principle of "hydraulic lock" of the piston in the cylinder when a load is applied to the piston at any stage (because the fluid is incompressible), and hydraulic fluid cannot be added to or removed from the closed chamber formed between the piston and the cylinder.

[0024] Another object of the present invention is to provide the above-mentioned "hydraulic lock" which supports the weight of a person climbing up and standing on the platform of the step ladder of the present invention.

[0025] Another object of the present invention is to make the "hydraulic lock" principle effective in a multi-stage telescopic hydraulic cylinder only by strictly ensuring that only the largest cylinder is supplied with pressurized hydraulic fluid first and its piston is extended almost to the end of the stroke, and only after that the next smaller cylinder should be supplied with hydraulic fluid, and this sequence should be continued for all stages of the multi-stage telescopic hydraulic cylinder. In the present invention, the above-mentioned necessary requirements are effectively achieved by the unique sliding valve arrangement structure adopted in the sealing assembly of the piston of the different stages of the multi-stage telescopic hydraulic cylinder.

[0026] As used herein, references to "the present invention" or the "invention" refer to exemplary embodiments, and not necessarily every embodiment encompassed by the appended claims.

[0027] A household step ladder comprises a large-area combined platform in the shape of a table top, and the platform is divided into two halves from the middle, and each half is respectively installed on one or preferably two multi-stage telescopic hydraulic cylinders, and the telescopic cylinders are connected to a hydraulic pneumatic accumulator through a pressure oil pipeline equipped with a three-position hydraulic valve and a necessary hydraulic check valve.

[0028] The invention falls within the category of step ladders, essentially because the user actually climbs steps formed by one or the other split half of a platform which, when not bearing a load, is in a position to be automatically raised to a higher level and is raised upwards and outwards relative to the other stationary, loaded platform half by a pair of multi-stage telescopic hydraulic cylinders attached to the half due to internal hydraulic pressure generated by pressurized oil supplied from a hydro-pneumatic accumulator through a pressure oil line equipped with a three-position hydraulic valve and a non-return valve, all during the climbing phase, and when the two platform halves are at the same level and locked in place (by using the cut-off or neutral position of the three-position hydraulic valve mentioned above), the user reaches any desired higher level and is able to comfortably stand on the wide modular platform with both feet at the same level and with the feet facing in any direction and to perform any task up to the level of the house ceiling by facing any of the four directions or working at any angle of 360 degrees.

[0029] After completing the task, all the person has to do is operate the foot lever provided to select the third position of the three-position hydraulic valve, which will bring the person back to the starting position at the low level, while all the hydraulic fluid in the 4 telescopic cylinders mentioned above will flow back into the hydro-pneumatic accumulator (under the pressure of the weight of the user descending from the higher level to the lower level and this potential energy will be stored in the hydro-pneumatic accumulator in the form of re-compressed compressed air in the air chamber for later use), and before leaving the platform, bring the foot lever back to select the cut-off / neutral position of the three-position hydraulic valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 are perspective views of a step ladder 1 at different stages, wherein: Figure 1 a shows the step ladder 1 before it is positioned for climbing, wherein the pre-step 13 is still located within the base unit assembly 2, and Figure 1 b. Figure 1 c. Figure 1 d represents the initial stage of climbing, showing platforms 20a and 20b at different heights from the floor at different stages;

[0031] Figure 2 Also a perspective view of a step ladder 1 in different stages, wherein Figure 2 a. Figure 2 b. Figure 2 c. Figure 2 d indicates the final stage of a possible climb;

[0032] Figure 3 is a graphical representation of a user on a step ladder 1 at different levels from floor level;

[0033] Figure 4 is a larger perspective view of the step ladder 1, with its main components clearly numbered;

[0034] Figure 5 is a perspective exploded view showing the various components of a step ladder;

[0035] Figure 6 is a perspective view of the step ladder 1 at its highest position, wherein one of the enclosures 25B is cut away to clearly show a pair of multi-stage telescopic hydraulic cylinders 15C and 15D therein;

[0036] Figure 7 is a perspective view of the step ladder 1 in its highest position, wherein the two enclosures 25A and 25B are removed, showing the multi-stage telescopic hydraulic cylinders 15A, 15B, 15C and 15D;

[0037] Figure 8 A cross-sectional view showing a single multi-stage telescopic hydraulic cylinder 15 (15C), showing its four stages 15Ca, 15Cb, 15Cc, 15Cd, seal assemblies 16A, 16B, 16C, spool valves 16Aa, 16Ba, and valve operating chains 17A, 17B attached to the spool valves 16Aa and 16Ba;

[0038] Fig. 9 express Figure 8 An enlarged cross-sectional view of the portion marked by dashes and dots in order to clearly show the seal assembly 16 and its various subcomponents 16Aa, 16Ba and the valve operating chains 17A, 17B;

[0039] Fig.10 A cross-sectional view showing a close-up portion of the details of the seal assembly 16A, with the spool valve assembly 16Aa in a closed state, not allowing hydraulic fluid to pass;

[0040] Fig.11 express Fig.10 perspective drawing;

[0041] Fig.12 A cross-sectional view showing a close-up portion of the details of the seal assembly 16A, with the spool valve assembly 16Aa in an open state, allowing hydraulic fluid to pass therethrough;

[0042] Fig.13 express Fig.12 perspective drawing;

[0043] Fig.14 A perspective view showing a separated portion of the two platform halves 20a and 20b together with the sliding bearing 21;

[0044] Fig.15 A perspective view showing two platform halves 20a and 20b in combination with a sliding bearing 21 assembled together;

[0045] Fig.16 is a perspective view of the enclosure 14 of the base unit assembly;

[0046] Fig.17 showing a perspective view of the base unit assembly 2 with the surrounding cover of the base unit assembly removed to show the internal components;

[0047] Fig.18 The representation shows a perspective view of the bottom part of the step ladder 1 when it is at its maximum height, giving a clear illustration of the three-position valve 8 and the mounting bases for the four multi-stage telescopic hydraulic cylinders and the four supporting legs 10 of the base plate 3;

[0048] Fig.19 Representation and Fig.18 The same perspective view as shown in , but since the pre-step 13 is pushed back to its normal position within the base unit assembly 2 when the step ladder 1 is not being used for climbing etc., the four retractable swivel wheel assemblies within the four support legs 10 are now extended from these support legs and are in their normal working position for moving the step ladder across the floor of a house;

[0049] Fig. 20 A schematic diagram showing some of the various components of the step ladder 1 and their connections using standard symbols;

[0050] Fig.21A perspective view showing another possible step ladder embodiment using only one multi-stage telescoping hydraulic cylinder to support each of the two split platforms and a pair of base mounted platform guides and supporting handrail arrangements for the step ladder.

[0051] Reference numerals list

[0052] 1-Complete hydraulic step ladder.

[0053] 2- Base unit assembly.

[0054] 3- Bottom plate.

[0055] 4-Hydraulic-pneumatic accumulator.

[0056] 4a - Hydraulic fluid chamber of the accumulator.

[0057] 4b-Air chamber of the accumulator.

[0058] 4c - Flexible membrane of the accumulator.

[0059] 4d - Air valve for accumulator.

[0060] 4e - hydraulic fluid channel of accumulator 4 to or from 4a.

[0061] 5-Mini air pump that runs on rechargeable batteries.

[0062] 5a- Compressed air line, which connects 5 with 4 and 7.

[0063] 6-Battery compartment.

[0064] 6a - Rechargeable battery.

[0065] 7-Mini air pump operation and display panel.

[0066] Pressure display on 7a-7.

[0067] 8-Three-position hydraulic valve.

[0068] 9-One-way check valve in the pipeline, 4 numbers (9A, 9B, 9C, 9D).

[0069] 10-Support legs under the base plate, 4 numbers (10A, 10B, 10C, 10D).

[0070] 11-Retractable swivel caster assembly, 4 numbered (11A, 11B, 11C, 11D).

[0071] 12-Lever operated retractable wheel assembly, 2 numbered (12A, 12B).

[0072] 13 - Built-in pre-step (inside 2) with pull-out and push-in capabilities (resulting in operation of levers 12A and 12B and operation of levers 11B and 11D).

[0073] 14 - Enclosure for base assembly (2).

[0074] 15-Multi-stage telescopic hydraulic cylinder, 4 numbers (15A, 15B, 15C, 15D).

[0075] 15C - Telescopic hydraulic cylinder stage, 4 numbers - 15Ca, 15Cb, 15Cc, 15Cd.

[0076] 16-Seal assembly, on the piston of each stage telescopic hydraulic cylinder 15C, 3 numbers (similar but not the same) - 16A, 16B, 16C.

[0077] Spring operated slide valve (in seal assemblies 16A and 16B), 2 pcs. Nos. - 16Aa, 16Ba.

[0078] 17- Valve operating chain for slide valves 16Aa and 16Ba, 17A, 17B

[0079] 18- Collapsed chain 17B, housed in a cylindrical chamber on the sealing assembly 16a.

[0080] 19- Collapsed chain 17A, housed in a cylindrical chamber at the bottom of stage 15Ca.

[0081] 20-Combined platform, when both platform halves are at the same level.

[0082] 20a - Left split half of a split but modular platform.

[0083] 20b - Right split half of a split but modular platform.

[0084] 21- Sliding bearings connecting the two platform halves, 2 numbers - 21A, 21B.

[0085] The foot lever on 22-20b is used to operate the three-position hydraulic valve 8.

[0086] 23 - Cable and socket mechanism for operating the three-position hydraulic valve 8 in the base unit 2 using the lever 22 on the platform half 20b.

[0087] 24 - switch for releasing the air pressure in the air chamber 4b of 4.

[0088] 25 - Enclosure (telescopic), for each pair of multi-stage telescopic hydraulic cylinders (15A and 15B) and (15C and 15D), 2 numbers - 25A, 25B.

[0089] 26-Supporting handrails, 2 numbers - 26A, 26B. DETAILED DESCRIPTION

[0090] The hydraulic step ladder 1 comprises a large-area modular platform in the shape of a table top, and the platform is divided into two halves in the middle, and each half acts as a step of the step ladder when it is at a different level and acts as a modular platform 20 of the step ladder when they are at the same level, which is achieved by each platform half 20a and 20b being respectively mounted on one or preferably two (as in the embodiment described herein) multi-stage telescopic hydraulic cylinders 15.

[0091] All four telescopic hydraulic cylinders 15A, 15B, 15C, 15D are connected to a hydraulic-pneumatic accumulator 4 having two flexible chambers, one for hydraulic fluid 4a and the other for compressed air 4b, the two flexible chambers being separated by a flexible membrane 4c so that compressed air can pressurize the hydraulic fluid and vice versa.

[0092] A rechargeable battery-operated mini air pump 5 (a mini version of the widely available rechargeable battery-operated air pumps for inflating car and bicycle tires) is provided together with its operating and display panel 7 and a battery compartment 6 for accommodating batteries 6a in order to increase or reduce the compressed air pressure in the air chamber 4b of the aforementioned hydropneumatic accumulator 4 when necessary.

[0093] The hydraulic pressurized fluid connection between the aforementioned hydropneumatic accumulator and the four multi-stage telescopic cylinders 15A, 15B, 15C, 15D is via a three-position hydraulic valve 8 .

[0094] The first position of the three-position hydraulic valve 8 is used to allow the pressurized hydraulic fluid to flow from the hydropneumatic accumulator 4 to each of the four multi-stage telescopic hydraulic cylinders mentioned above, which are arranged in two pairs of multi-stage telescopic hydraulic cylinders, and the fluid lines leading to each pair of multi-stage telescopic hydraulic cylinders are provided with separate one-way check valves 9A and 9B (see also the attached figure). Fig. 20 Schematic diagram of the ).

[0095] The second position of the three-position hydraulic valve 8 would be a standby and shut-off position for shutting off flow in both directions.

[0096] The third position of the three-position hydraulic valve 8 is used to return the hydraulic fluid from the two pairs of multi-stage telescopic hydraulic cylinders mentioned above to the hydraulic-pneumatic accumulator through a line bypassing the check valves 9A and 9B mentioned above, but the line is provided with two different check valves 9C and 9D to avoid cross flow between the two pairs of multi-stage telescopic hydraulic cylinders.

[0097] In order to climb up the step ladder to perform a specific task at a specific location at a higher level from the floor of the house, the person first rolls the step ladder (which will usually be placed on its four spring-loaded retractable swivel castors 11) to the specific location and pulls out the pre-step 13 with his or her legs, which causes (operation of the lever 12) the four spring-loaded retractable swivel castors 11 to retract into the four supporting legs 10 under the base plate 3 and now places the step ladder firmly and directly on the floor; preventing the possibility of lateral movement of the step ladder when the user climbs up and down or stands on the step ladder at a level higher than the ground and performs any task at that level.

[0098] Once the step ladder is properly positioned as explained above, he or she would ascend the modular platform 20 (which is formed by two platform halves 20a and 20b, which are at the same lowest level from the floor) by utilizing the pre-step 13 and by placing one foot on each platform half 20a and 20b respectively, and then operate the foot lever 22 provided on 20b, which in turn would operate the three-position hydraulic valve 8 mentioned above from the standby cut-off position to the first position, and then when the person lifts one leg and releases the load on one half of the platform 20, that half of the platform would begin to rise slowly until the foot load is transferred back to that half of the platform (how long or how slowly the user applies the foot load results in the stepless variable height of the step and platform 20), or it reaches the preset limit of 4 inches and is locked in this higher position due to the "hydraulic lock" principle caused by the one-way check valve arrangement structure provided, the "hydraulic lock" principle has been explained in detail in paragraph 0019 above.

[0099] The person then raises himself / herself by lifting his / her other leg and releasing the load from the other platform half to transfer his / her weight to the higher positioned platform half, which will now begin to rise and come to a level with the first mentioned platform half and lock itself in this position when a load is applied to the other platform half, and this process can be repeated until both platform halves are in a horizontal position at the desired height, and then by operating the foot lever, the second position of the three-position valve can be selected, which second position will be a cut-off or neutral position, after which both legs can be placed in any position on the modular platform to assume a comfortable posture and perform any task facing any of the four directions and facing all angles in 360 degrees up to the level of the room ceiling.

[0100] After completing the task, all the person has to do is operate the foot lever 22 and bring it to its third position, which in turn selects the third position of the three-position hydraulic valve located in the base unit assembly 2 at the underside of the base plate 3, which brings the person back to the low-level starting position, while all the hydraulic fluid in the four multi-stage telescopic hydraulic cylinders mentioned above flows back into the hydraulic-pneumatic accumulator (under the weight pressure of the user descending from the higher level to the lower level, and this potential energy is stored in the hydraulic-pneumatic accumulator in the form of re-compressed compressed air in the air chamber for later use), and before leaving the platform, bring the foot lever 22 back to the starting position, selecting the cut-off / neutral position of the three-position hydraulic valve 8.

[0101] The invention falls within the category of step ladders, essentially in that the user actually climbs steps formed by one or the other split half of a platform which, when not bearing a load, is in a position to be automatically raised to a higher level, being raised upwards and outwards relative to the other stationary, load-bearing platform half by a pair of multi-stage telescopic hydraulic cylinders attached to the half due to internal hydraulic pressure generated by pressurized oil supplied from a hydro-pneumatic accumulator through a pressure oil line equipped with a three-position hydraulic valve and a non-return valve, and all of the above occurs during the climbing phase.

[0102] When the two platform halves are at the same level and locked in place (by using the cut-out or neutral position of the three-position hydraulic valve as explained above), the user reaches any desired higher level and can comfortably stand on the wide modular platform with both feet at the same level.

[0103] In this case, the user feels like standing on flat ground and can perform any task facing any of the four directions or at any angle of 360 degrees with both feet facing in any direction, the climbing down process has been explained.

[0104] The main components of the present invention are:

[0105] The base unit assembly 2 comprises a base plate 3 for mounting two pairs of multi-stage telescopic hydraulic cylinders 15, a small capacity hydraulic pneumatic accumulator 4, a three-position hydraulic valve 8, a hydraulic fluid line, said hydraulic fluid line connecting all of the above through a suitably positioned check valve 9. The base plate 3 has four supporting legs 10 (10A, 10B, 10C, 10D) at its bottom side with non-slip footing for resting on the floor during use of the step ladder for climbing etc. In addition to the mentioned four supporting legs, the base plate is also provided with four spring-loaded retractable swivel caster wheel assemblies 11 arrangement structures (built into the above mentioned legs) for raising and supporting the weight of the entire assembly of the present invention so as to easily move the entire assembly back and forth on the floor of the house.

[0106] The base unit assembly 2 also has a built-in pre-step 13 arrangement to facilitate any user to step onto the modular platform 20 of the step ladder at its lowest position when starting to climb the step ladder.

[0107] After the user has rolled the step ladder and placed it at the desired location, in order to climb to perform any task at a level higher than the floor level, the user first pulls the provided pre-step 13 out into place with his or her legs.

[0108] The above-mentioned action of the user causes the retractable swivel caster assembly 11 to retract, and the step ladder is placed directly and firmly on the floor, without the possibility of lateral movement of the step ladder when the user climbs and works on the step ladder.

[0109] When the pre-step is pulled out, it will also trigger the limit switch to send a signal to the mini air pump operation and display panel 7 to ensure that the air pressure in the air chamber 4b of the hydraulic-pneumatic accumulator 4 has a preset pressure by controlling the operation of the mini air pump 5 as required.

[0110] After use of the step ladder is completed, the user uses his or her legs to push the pre-step 13 back to its original position within the base unit assembly 2, and this in turn pushes the retractable swivel castor arrangement 11A, 11B, 11C, 11D back to its original working position, allowing the step ladder to be comfortably rolled on the floor and moved anywhere in the house.

[0111] The base unit assembly 2 also includes the already mentioned rechargeable battery-operated mini air pump 5 (a mini version of the widely available rechargeable battery-operated air pumps for inflating car and bicycle tires), which is connected to the compressed air chamber 4b of the above-mentioned hydraulic-pneumatic accumulator 4, and the mini air pump 5 is provided with an operating and display panel 7 as mentioned above and is also provided with a mountable and removable and rechargeable battery device, which includes a battery compartment 6 for accommodating a rechargeable battery 6a for operating the air pump when required.

[0112] Multi-stage telescopic hydraulic cylinder arrangement structure 15:

[0113] Two pairs of multi-stage telescopic hydraulic cylinders (one pair is 15A and 15B and the other pair is 15C and 15D) extend outward and upward from the base unit assembly 2, and each pair of multi-stage telescopic hydraulic cylinders is enclosed in their own separate telescopic enclosure 25A for enclosing 15A and 15B and enclosure 25B for enclosing 15C and 15D, one pair of the mentioned multi-stage telescopic hydraulic cylinders 15A and 15B is installed in the split half 20a of the modular platform 20, and the other pair of multi-stage telescopic hydraulic cylinders 15C and 15D is installed on the other split half 20b of the modular platform 20.

[0114] Multi-stage telescopic hydraulic cylinder 15: The stages and details of only one multi-stage telescopic hydraulic cylinder 15C are explained below.

[0115] In any telescopic hydraulic cylinder with multiple stages, the first stage is the largest cylinder in the cylinders, and the piston of this stage, after reaching its maximum forward movement stroke, will serve as the cylinder of the next stage, and this applies to all stages in a continuous order until the last stage. In the present invention, even if the cylinder size / diameter is relatively small, the above-mentioned operation sequence is also applied to its work.

[0116] The present invention ensures that hydraulic fluid is supplied only to the piston of the largest cylinder first and extends it almost to its end stroke position and only thereafter is hydraulic fluid supplied to the next smaller cylinder and this sequence continues through all stages, all of which is achieved through the operation of the slide valve arrangement structure included in the present invention.

[0117] The spool valve arrangement comprises spool valves 16Aa and 16Ab (contained in a sealing assembly forming the bottom portion of each piston of the multi-stage telescopic hydraulic cylinder 15C and which valve acts as a conventional one-way spring-operated hydraulic check valve with override capability) which are held in a normally closed position by springs, the spool valve of a particular piston of a particular stage being brought to its open position when it has almost reached the end of its travel.

[0118] The automatic opening of the slide valve and the admission of hydraulic fluid to the next stage occurs by providing a chain arrangement of fixed length, which is attached to the top part of the sealing assembly of the mentioned slide valve and the previous stage cylinder in the case of the second stage 15Cb of the multi-stage telescopic hydraulic cylinder 15C, and to the bottom of the cylinder in the case of the second stage 15Ca of the multi-stage telescopic hydraulic cylinder 15C, the fixed chain length being a few millimeters shorter than the maximum stroke of the piston mentioned above, whereby the now tightened chain actually pulls and opens the slide valve by counteracting the spring pressure used to keep the valve normally closed.

[0119] It can be explained here that the sealing assembly 16A at the bottom of the first-stage piston and the bottom mounting portion of the first-stage cylinder of the present invention is provided with "barrel-shaped" chambers 18 and 19.

[0120] The "barrel" chambers mentioned above have sufficient volume to safely contain a collapsed chain (the chain will collapse into a heap but still maintain the aforementioned connection) when the pistons of each stage are in their retracted bottom positions in their respective cylinders.

[0121] A split tabletop platform arrangement with a modular platform 20.

[0122] As already explained before, the "platform" is an important and critical part of the step ladder, which ensures comfort and safety when standing and working on the step ladder. Domestic housework tasks in various occasions and situations and to be performed by people of different heights require the platform to be at a stepless level above the ground.

[0123] In the present invention, the split countertop platform arrangement structure has one platform half of each of the two platform halves, which acts as a step of the step ladder for the user to climb to a higher level, because each half has the ability to automatically and slowly rise when not under load through the provided hydraulic arrangement structure, whereby when the user stands on each platform half of the platform half with one foot respectively, lifts one of his / her feet off the first platform half 20a, the first platform half will begin to rise slowly until the user steps on the first platform half and applies some load or the first platform half reaches the set height for the steps of the step ladder. 4 inch maximum height limit, it is locked at this level due to the "hydraulic lock" principle, when the user raises himself by transferring all his weight to the now raised first platform half 20a, and once the other half 20b has been unlocked, the other half begins to rise until the other half comes to a level with the raised first platform half and locks in place, resulting in both platform halves being at the same level, resulting in a full width platform (of the combined two platform halves), whereby the user decides the height increment of the platform by deciding the step height that is most comfortable for that user, the user repeats this process to reach his or her desired combined platform height.

[0124] The second split half 20b of the platform described above would be the one having the appropriate position for the foot-operated lever 22 for properly positioning the three-position valve within the base unit assembly 2, and the second split half 20b also having a switch for controlling the air pressure in the air chamber 4b of the hydro-pneumatic accumulator 4 when required.

[0125] The two split halves 20a and 20b of the platform are interconnected by a sliding bearing 21A and 21B arrangement to improve stability by preventing any possible lateral movement between the two halves when they are raised or lowered relative to each other (see the drawings).

[0126] Hydropneumatic accumulator4.

[0127] The present invention comprises a small capacity (e.g. 3 to 4 liter capacity) hydropneumatic accumulator, which preferably has 50% of the volume for a hydraulic fluid chamber and the remaining 50% of the volume for compressed air, the oil chamber being connected to four multi-stage telescopic hydraulic cylinders 15A, 15B, 15C, 15D via a hydraulic pressure line via a three-position hydraulic valve 8 and a plurality of hydraulic check valves 9 positioned in said line.

[0128] The compressed air chamber 4b of the hydropneumatic accumulator 4 is connected to a mini air pump 5 (explained in detail in the description) together with its operating and display panel connection 7, which is arranged to control the compressed air pressure in the compressed air chamber 4b of the hydropneumatic accumulator 4 when necessary for the normal operation of the invention (see also the attached Fig. 20 Schematic diagram of the ).

[0129] Seal assembly 16: Three numbers - similar but not identical.

[0130] Each hydraulic piston in each of the 4 multi-stage telescopic hydraulic cylinders included in the present invention, which together form different stages of cylinders, will have a sealing assembly on the bottom, which sealing assembly is appropriately composed of a piston guide and a piston seal. The sealing assembly will have a "sliding piston assembly" in the middle (explained in detail in the accompanying drawings) and at the top the sealing assembly is provided with a "barrel-shaped" chamber for accommodating the collapsed valve operating chain when the pistons are at the bottom of their stroke in their cylinders. These can be more clearly understood from the drawings and the description attached thereto.

[0131] Three-position hydraulic valve 8:

[0132] The three-position hydraulic valve 8 is provided in the hydraulic circuit between the hydropneumatic accumulator 4 and the four multi-stage telescopic hydraulic cylinders 15A, 15B, 15C and 15D.

[0133] The multi-stage telescopic hydraulic cylinders 15A, 15B, 15C and 15D are arranged in pairs, one pair consisting of 15A and 15B and the other pair consisting of 15C and 15D. The first position of the three-position hydraulic valve 8 is used to allow the pressurized hydraulic fluid to flow from the hydropneumatic accumulator through the one-way check valves 9A and 9B (these two valves do not allow reverse flow and are such valves that contribute to the "hydraulic lock" arrangement structure, which supports the weight of the person climbing up and standing on the step ladder platform in the present invention, explained in detail in paragraph 0019) to each of the above-mentioned pairs; the second position will be a standby and neutral position for cutting off the supply; and the third position is used to return the hydraulic fluid from the above-mentioned 4 telescopic hydraulic cylinders to the hydropneumatic accumulator through a path bypassing the above-mentioned check valves 9A and 9B, but the line is provided with two different check valves 9C and 9D to avoid cross flow between the two pairs of multi-stage telescopic hydraulic cylinders (see attached Fig. 20 Schematic diagram of the ).

[0134] The three positions of the three-position hydraulic valve 8 located in the base unit assembly 2 can be selected by a foot-operated lever 22 mechanism set at an appropriate position on the second split half 20b of the platform, and the foot-operated lever is connected to the three-position hydraulic valve 8 located in the base unit assembly 2 through a flexible cable and sleeve mechanism arrangement structure 23 (similar to the commonly used bicycle clutch cable).

[0135] The operation of selecting the three different positions of the three-position hydraulic valve 8 located inside the base assembly 2 and on the bottom side of the base plate 3 is performed by selecting the three different positions of the foot lever 22 arranged on the split platform 20b on the right side, wherein the foot lever 22 is linked to the three-position hydraulic valve 8 through the flexible pull wire and sleeve mechanism 23 provided (this is not clearly shown in the submitted drawings).

[0136] In a preferred embodiment, a household hydraulic step ladder is characterized in that the heights of the steps and the platform can be changed steplessly, and the step ladder comprises: a large-area combined platform, which is divided into two platform halves; wherein the platform halves act as steps of the step ladder at different levels, and the platform halves act as a combined platform of the step ladder at the same level; one or more multi-stage telescopic hydraulic cylinders connected to the platform halves, wherein the multi-stage telescopic hydraulic cylinder can raise the platform half that is not loaded to a higher level relative to the other platform half that is loaded; a base unit assembly, wherein the base unit assembly includes a base plate having four legs for being placed on the floor; wherein the multi-stage telescopic hydraulic cylinder is mounted on the base unit assembly, wherein each platform half is mounted on the multi-stage telescopic hydraulic cylinder.

[0137] In one embodiment, each pair of multi-stage telescopic hydraulic cylinders carries a platform half, wherein the modular platform has the ability to independently move each platform half relative to the other platform half, wherein the platform halves are interconnected by a pair of sliding bearings.

[0138] In one embodiment, the multi-stage telescopic hydraulic cylinder is connected to a small-capacity hydraulic-pneumatic accumulator located in the base unit assembly through a hydraulic pressure line passing through a three-position hydraulic valve and a plurality of check valves, and two pairs of multi-stage telescopic hydraulic cylinders extend upward and outward from the base unit assembly, and each pair of multi-stage telescopic hydraulic cylinders carries a platform half, and the modular platform of the step ladder acts as a large-area modular platform when the two platform halves are at the same level, so as to enable a user to stand comfortably at a higher level from the floor and perform any task.

[0139] In one embodiment, the base unit assembly includes a mini, rechargeable battery-operated air pump together with an electrical panel having a compressed air pressure display and multiple control switches for operating the air pump, which is in turn connected to the air chamber of the hydro-pneumatic accumulator via an air line and is thereby used to regulate the pressure of the compressed air in the air chamber of the hydro-pneumatic accumulator.

[0140] In one embodiment, the base plate of the base unit assembly has four support legs with non-slip feet for resting on the floor when the step ladder is used for climbing and working by standing on the modular platform, wherein the base plate includes four spring-loaded retractable swivel caster assemblies built into the support legs for raising and supporting the weight of the step ladder for easy movement back and forth on the floor.

[0141] In one embodiment, a pre-step is built into the base unit assembly for allowing the user to conveniently step onto the platform of the step ladder at the lowest position of the platform of the step ladder when starting to climb the step ladder. After the user rolls the step ladder and places it in the desired position for climbing, the user first pulls the provided pre-step out into position with his or her legs. During this action of the user, a combination of a lever and roller arrangement structure provided in the base assembly automatically operates to retract the retractable swivel caster assembly, and thereby directly and firmly places the step ladder on the four supporting legs on the floor, so that when the user climbs and works on the step ladder, there is no possibility of lateral movement of the step ladder; wherein, after the use of the step ladder is completed, the user pushes the pre-step back to its original position in the base assembly with his or her feet, and this in turn automatically brings the retractable swivel caster assembly back to its initial position, allowing the step ladder to roll and move comfortably on the floor.

[0142] In one embodiment, a slide valve arrangement comprises a slide valve contained in a sealing assembly forming the bottom portion of each stage of a multi-stage telescopic hydraulic cylinder to ensure a strictly progressive extension and retraction of the different stages even if the multi-stage telescopic hydraulic cylinder is of small diameter and operates with a low pressure and low volume hydraulic section, wherein the slide valve acts as a conventional one-way spring-operated hydraulic check valve with an override function capability, the slide valve being held in a closed position by a spring and the slide valve of the piston of a particular stage being automatically brought into an open position after it has almost reached the end of its stroke, allowing hydraulic fluid to enter the next stage via a chain arrangement of a fixed length connected to the slide valve of the piston and the bottom of the cylinder of the particular stage, the fixed chain length being a few millimeters shorter than the maximum stroke of the piston, wherein the tightened chain actually pulls and opens the slide valve by counteracting the spring pressure holding the slide valve closed.

[0143] In one embodiment, the seal assembly at the bottom of each piston is provided with a cylindrical chamber of sufficient volume to safely contain the chain when the piston of each stage is in its retracted bottom position in the cylinder of each stage (wherein the chain collapses into a pile and remains connected).

[0144] In one embodiment, a three-position hydraulic valve is located in a hydraulic circuit between a hydro-pneumatic accumulator and two pairs of multi-stage telescopic hydraulic cylinders, wherein a first position of the three-position hydraulic valve is used to allow pressurized hydraulic fluid to flow from the hydro-pneumatic accumulator through a one-way check valve into each pair of multi-stage telescopic hydraulic cylinders, wherein a second position is a standby and neutral position for cutting off the flow of hydraulic fluid in both directions, and wherein a third position is used to allow pressurized hydraulic fluid to return from the two pairs of multi-stage telescopic hydraulic cylinders to the hydro-pneumatic accumulator through a path bypassing the one-way check valve, wherein the third position is selected when a user needs to return to a low-level starting position.

[0145] In one embodiment, a built-in system is provided for a step ladder user to determine the height of the steps and platforms based on his or her posture and movement when standing on the platform of the step ladder.

[0146] In a preferred embodiment, the method for operating a household hydraulic step ladder according to claim 1 includes the following steps: a user climbs the steps formed by one or the other platform half of the modular platform; automatically raises the platform half to a higher level relative to the other stationary load-bearing platform half by a multi-stage telescopic hydraulic cylinder attached to the platform half; during climbing, the multi-stage telescopic hydraulic cylinder is raised upward and outward due to the pressure in the telescopic cylinder, the pressure being created by the following pressurized hydraulic fluid, which is supplied to the telescopic hydraulic cylinder from a hydraulic-pneumatic accumulator through a pressure hydraulic fluid line equipped with a three-position hydraulic valve and a check valve; and when the two platform halves are at the same level, the user selects the second (flow cut-off) position of the three-position hydraulic valve to lock into a horizontal position.

[0147] In one embodiment, the platform half is brought back to the starting position at the lower level by the user operating the foot lever 22 and bringing the foot lever to its third position, wherein the foot lever selects the third position of the three-position hydraulic valve, wherein the third position of the hydraulic valve is used to return the hydraulic fluid from the multi-stage telescopic hydraulic cylinder to the hydro-pneumatic accumulator located in the base unit assembly 2 at the underside of the floor 3. The potential energy under the weight pressure of the user descending from the upper level to the lower level is stored in the hydro-pneumatic accumulator in the form of re-compressed compressed air in the air chamber for later use, and the user brings the foot lever 22 back to the starting position, selecting the cut-off / neutral position of the three-position hydraulic valve 8 before leaving the platform.

[0148] In one embodiment, the method includes the steps of raising one of the platform halves of the modular platform as a step when not under load, locking it at this level once a user steps on the platform half and applies a load, wherein the step and platform 20 have an infinitely variable height that is caused based on how soon or how slowly the user applies a foot load, wherein a built-in maximum possible step height is 4 inches, and when the user transfers weight to the raised platform half and unloads the load from the other platform half, raising the other platform half until it comes to a level with the raised platform half and locks in place, causing the two platform halves to be at the same level, thereby creating a large area modular platform; and wherein the height increments of the platform halves are determined by the user, and the user repeats the process to achieve a modular platform height that can perform desired tasks at any level in a comfortable and safe manner.

[0149] In one embodiment, the user is at a desired high level and is able to comfortably stand on a wide modular platform with both feet at the same level, similar to standing on flat ground, and with both feet facing in any direction, and in a position on the platform to perform any task by facing in any of four directions or working at all angles of 360 degrees.

Claims

1. A household hydraulic step ladder, characterized in that: The height of the steps and platforms can be changed steplessly, and the step ladder comprises: A large modular platform with step ladders, the modular platform is divided into two platform halves; wherein the platform halves act as steps of a step ladder at different levels, and the platform halves act as a combined platform of a step ladder at the same level; one or more multi-stage telescopic hydraulic cylinders connected to the platform halves, wherein the multi-stage telescopic hydraulic cylinders are capable of raising the unloaded platform half to a higher level relative to the other loaded platform half; a base unit assembly, the base unit assembly including a base plate having four legs for resting on a floor; Among them, the multi-stage telescopic hydraulic cylinder is installed on the base unit assembly. Each platform half is mounted on a multi-stage telescopic hydraulic cylinder.

2. The household hydraulic step ladder according to claim 1, wherein: Each of the pairs of multi-stage telescopic hydraulic cylinders carries a platform half, wherein the modular platform has the ability to independently move each platform half relative to the other platform half, wherein the platform halves are interconnected by a pair of sliding bearings.

3. The household hydraulic step ladder according to claim 1, wherein: The multi-stage telescopic hydraulic cylinder is connected to a small-capacity hydraulic-pneumatic accumulator located in the base unit assembly through a hydraulic pressure line passing through a three-position hydraulic valve and a plurality of check valves, and two pairs of the multi-stage telescopic hydraulic cylinders extend upward and outward from the base unit assembly, and each pair of the multi-stage telescopic hydraulic cylinders carries a platform half, and the combined platform of the step ladder acts as a large-area combined platform when the two platform halves are at the same level, so as to enable a user to stand comfortably at a higher level from the floor and perform any task.

4. The household hydraulic step ladder according to claim 1, wherein: The base unit assembly includes a mini, rechargeable battery-operated air pump together with an electrical panel with a compressed air pressure display and multiple control switches for operating the air pump, which is in turn connected to the air chamber of the hydro-pneumatic accumulator via an air line and is therefore used to regulate the pressure of the compressed air in the air chamber of the hydro-pneumatic accumulator.

5. The household hydraulic step ladder according to claim 1, wherein: The base plate of the base unit assembly has four support legs with non-slip feet for resting on the floor when the step ladder is used for climbing and working by standing on the modular platform, wherein the base plate includes four spring-loaded retractable swivel caster assemblies built into the support legs for raising and supporting the weight of the step ladder for easy movement back and forth on the floor.

6. The household hydraulic step ladder according to claim 1, wherein: A pre-step is built into the base unit assembly for enabling the user to conveniently step onto the platform of the step ladder at the lowest position of the platform of the step ladder when starting to climb the step ladder. After the user rolls the step ladder and places it in the desired position for climbing, the user first pulls the pre-step into place with his or her legs. During this action of the user, a combination of a lever and roller arrangement structure provided in the base assembly automatically operates to retract the retractable swivel caster assembly and thereby place the step ladder directly and firmly on the floor on the four supporting legs. When the user climbs and works on the step ladder, there is no possibility of lateral movement of the step ladder. Therein, after use of the step ladder is completed, the user uses his or her foot to push the pre-step back to its original position within the base assembly, and this in turn automatically brings the retractable swivel caster assembly back to its initial position, allowing the step ladder to roll and move comfortably on the floor.

7. The household hydraulic step ladder according to claim 1, wherein: The slide valve arrangement comprises a slide valve contained in a sealing assembly forming the bottom portion of each stage of the multi-stage telescopic hydraulic cylinder to ensure a strictly progressive extension and retraction of the different stages even though the multi-stage telescopic hydraulic cylinder is small in diameter and operates with low pressure and low volume hydraulic parts, Therein, the slide valve acts as a conventional one-way spring-operated hydraulic check valve with an override function capability, the slide valve being held in a closed position by a spring and the slide valve of the piston of a particular stage being automatically brought into an open position after it has almost reached the end of its stroke, allowing the hydraulic fluid to enter the next stage via a chain arrangement of a fixed length connected to the slide valve of the piston and the bottom of the cylinder of the particular stage, the fixed chain length being a few millimeters shorter than the maximum stroke of the piston, wherein the taut chain actually pulls and opens the slide valve by counteracting the spring pressure holding the slide valve closed.

8. The household hydraulic step ladder according to claim 3, wherein: The seal assembly at the bottom of each piston is provided with a cylindrical chamber of sufficient volume to safely contain the chain when the piston of each stage is in its retracted bottom position in the cylinder of each stage (wherein the chain collapses into a pile and remains connected).

9. The household hydraulic step ladder according to claim 1, wherein: A three-position hydraulic valve is located in the hydraulic circuit between the hydro-pneumatic accumulator and the two pairs of multi-stage telescopic hydraulic cylinders, wherein a first position of the three-position hydraulic valve is used to allow pressurized hydraulic fluid to flow from the hydro-pneumatic accumulator through the one-way check valve into each pair of multi-stage telescopic hydraulic cylinders, wherein a second position is a standby and neutral position for cutting off the flow of hydraulic fluid in both directions, and The third position is used to return the pressurized hydraulic fluid from the two pairs of multi-stage telescopic hydraulic cylinders to the hydraulic pneumatic accumulator through a path bypassing the one-way check valve, wherein the third position is selected when the user needs to return to a low-level starting position.

10. The household hydraulic step ladder according to claim 1, wherein: There is a built-in system for the step ladder user to determine the height of the steps and platforms based on his or her posture and movement when standing on the platform of the step ladder.

11. A method for operating a domestic hydraulic step ladder, the domestic hydraulic step ladder being the domestic hydraulic step ladder according to claim 1, the method comprising the following steps: Climbing by a user of steps formed by one or the other platform half of a modular platform; The platform halves are automatically raised to a higher level relative to the other stationary, load-bearing platform half by means of multi-stage telescopic hydraulic cylinders attached to the platform halves; During climbing, the multi-stage telescopic hydraulic cylinder is raised upward and outward due to the pressure within the telescopic cylinder, the pressure being created by a pressurized hydraulic fluid supplied to the telescopic cylinder from a hydro-pneumatic accumulator through a pressurized hydraulic fluid line equipped with a three-position hydraulic valve and a check valve; and When the two platform halves are at the same level, the second (flow shutoff) position of the three-position hydraulic valve is selected by the user to lock into a horizontal position.

12. A method for operating a domestic hydraulic step ladder according to claim 11, wherein: The platform half is brought back to the low-level starting position by the user operating the foot lever 22 and bringing it to its third position, wherein the foot lever selects the third position of the three-position hydraulic valve, wherein the third position of the hydraulic valve is used to return hydraulic fluid from the multi-stage telescopic hydraulic cylinder to the hydro-pneumatic accumulator located in the base unit assembly 2 on the underside of the base plate 3.

13. A method for operating a domestic hydraulic step ladder according to claim 12, wherein: The potential energy under the weight pressure of the user descending from the higher level to the lower level is stored in the hydro-pneumatic accumulator in the form of re-compressed compressed air in the air chamber for later use, and the user brings the foot lever 22 back to the starting position, selecting the cut-off / neutral position of the three-position hydraulic valve 8 before leaving the platform.

14. A method for operating a domestic hydraulic step ladder, the domestic hydraulic step ladder being the domestic hydraulic step ladder according to claim 1, the method comprising the following steps: One of the platform halves of the modular platform is raised to serve as a step when not bearing load. Once the user steps onto half of the platform and applies a load, it is locked at this level. Therein, the step and platform 20 has a continuously variable height based on how long or how slowly the user applies the foot load, with a built-in maximum possible step height of 4 inches. When the user transfers weight to the raised platform half and unloads the other platform half, the other platform half is raised until it comes to one level with the raised platform half and locks into place, causing the two platform halves to be at the same level, thereby creating a large-area modular platform; and Therein, the height increments of the platform halves are determined by the user, and the user repeats the process to achieve a height of the modular platform that allows the desired task to be performed at any level in a comfortable and safe manner.

15. The method for operating a domestic hydraulic step ladder according to claim 11, wherein: The user is at a desired high level and can comfortably stand on the wide modular platform with both feet at the same level, similar to standing on flat ground, and with both feet facing in any direction, and in one position on the platform to perform any task by facing in any of the four directions or working at all angles of 360 degrees.

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