ADJUSTABLE OLEOPNEUMATIC SUPPORT, PARTICULARLY FOR OFFICE CHAIRS WITH CENTRAL COLUMN

Abstract: The present invention concerns an adjustable oleopneumatic support, particularly for the height adjustment of the seat of office chairs with central columns. The oleopneumatic element includes a hollow cylindrical body (2) with a packing member (12) realizing an upper and a lower cavity (22-23, 11), the respective lower end being rigidly linked to the base of the chair, and a coaxial hollow stem (15), the head of which is rigidly linked to the seat of same chair, said hollow coaxial stem (15) being rigidly connected to a piston (20) which defines inside said upper cavity two chambers, an upper and a lower chamber respectively (22, 23) both containing fluid; said hollow coaxial stem (15) being provided inside with valvular coaxial actuation means (33-43) controlling a passage for a hydraulic fluid (40, 41) the respective outlets being placed above and below the piston (20) respectively; said lower cavity (11) being able to contain compressed gas.

Description: Adjustable oleopneumatic support, particularly for office chairs with central column The present invention concerns an adjustable oleopneumatic support, particularly fit for chairs with central column In chairs with central column are commonly used, as adjustable, gas shock-absorber supports that, generally placed in a vertical position inside a guiding telescopic cladding, with the ends respectively connected to the base and the seat of the chair, support in a spring way the load applied. Such well known gas shock-absorbers are mainly constituted of a piston which, at the application of the load, compresses the gas stored inside until its pressure balances the action of the load; in such condition of equilibrium is the same pressure reached by the gas that, acting on the piston, supports the chair and the load applied on it. The height adjustment of the seat can be effected by opening, with predisposed valvular means, an inner passage that make into comunication the chamber in which slides the piston with an adjacent compressed gas chamber. The opening of the passage in condition of load absence causes the gas exit from said chamber which, expanding, lift the piston; vice versa, the contemporary reversal opening condition by application of a sufficiently heavy load, causes the lowering of the piston and the convey of a further quantity of gas into said chamber with the raising of the pressure in its interior. Such well known gas shock-absorbers, though revealing themselves valid from an exluεively pratical point of view, are not free for inconveniences, among which goes principally enumerated the fact that the gas compressed in their interior reaches a very high pressure value, which notoriously entails serious leaking problems, with possible gas escapes and discharge of the shock-absorber, and above all the arising on the material of remarkable solicitations that may cause the yelding, with possible prejudice for the users. In relation to both the stress generated by the high pressure, aiming "bo keep within acceptable limits -the thickness of the components, and to avoid a too high springing run, are generally used small-diameter tubular elements which, however, resulting subject to high load points, do not possess the necessary stability and must be normally assembled in combination with complementary devices, such as guiding telescopic claddings of bigger dimensions. The scope of the present invention is to eliminate the drawbacks above mentioned in well known types of gas shock-absorbers, conceiving an adjustable support in which the height adjustment occurs by fluid shifting from one chamber to the other, without compression, so as "to keep low in every situation the value of the interior pressure and -hat, besides, uses as operating fluid an unco pressable liquid, semplifying appreciably all the problems connected with gasproof at high pressure. In -t 'amhi-t of the .task above exposed, a particular purpose of the invention is to achieve an adjustable oleopneumatic elemerrt which, for its own peculiar structural characteristics, can support with security and without buckling the full stress springing from the loads applied on the chair, so as to be used singularly, without employing complementary devices. An important purpose is to equip the oleopneumatic support with valvular means of adjustment which, besides being extremely functional and reliable, present an encumbrance extremely reduced, so as to be easily lodged inside the same supporting element, without requiring particular constructive complications. Not last is the purpose to conceive a structure of adjustable oleopneumatic support that results easily obtainable starting from elements and materials of common procurement in commerce, in which the components are rapidly assemblable and that, besides, results competitive from an economic point of view. The task above exposed, as well as the already mentioned purposes and others that will better appear later, are reached by an adjustable oleopneumatic support, particularly for chairs with central column, including a hollow cylindrical body, of which lower base is rigidly linkable to the basement of the chair, and a coaxial stem, of which head is rigidly linkable to the seat of the same chair, which, according to the invention, distinguish itself for the fact that said ste is fuently coupled, leak proof, with the upper base of said cylindrical body and with a transversal septum which separates the interior of said cylindrical body in an upper cavity, developing itself in correspondence to said upper base, and in a lower cavity developing itself in the opposite side. Said stem being rigidly associated to a piston which defines inside the upper cavity two chambers, both containing fluid; the shifting of said piston inside said upper cavity causes, through valvular means, the transitory passage of said fluid from one chamber to the other allowing, for the contrast and action of a compressed gas present inside of said lower cavity, the height adjustment of the seat of the chair. Further characteristics and advantages of the invention will result more from the description of a preferred but not exclusive way of execution of the device, illustrated as a non limitative example-in the enclosed drawings, in which: Figure 1 is a side view of the oleopneumatic element, in which the cylindrical body is represented in a longitudinal section; Figure 2 is a longitudinal section that evidences the valvular means in a closed positiion; Figure 3 is a longitudinal section that evidences the valvular means in an opened position; Figure 4 is a perspective view of a chair with central column. With reference to the -drawings, ran adjustable oleopneumatic support, inclusively indicated with reference number 1, includes a hollow cylindrical body 2, opportunely constituted of a first tubular element 3 closed, leak proof, in its own lower base, externally tapered, by a cap 4. The cap 4 is fixed, with a first elastic ring 5 and is then equipped with a first sealing gasket ring 6; in the same way, in other realizable forms; the cap 4 can .directly be fixed to -the first -tubular element 5 by a circumferential welding cord. To the base opposite to the cap 4, on the first tubular element 3 is connected a holed stem guiding plate 7, fixed hydraulic seal for example by an elaεting ring 8, with the interposition of a second sealing gasket ring 9. According to the invention, the inside of the cylindrical body 2 is divided into two cavities, respectively upper 10 and lower 11, by a holed transversal chamber partition septum 12, which is advantageously bound xxr fixed, leak proof, to the first tubular element 3 by a third eleεtic ring 13 and with the interposition of a third sealing gasket ring 14. Coaxially to the cylindrical body 2, the oleopneumatic element 1 includes a stem 15, axially sliding through both the stem guiding plate 7 and the chamber partitium septum 12, according to couplings rendered leak proof by the presence of seal means, respectively advantageously constituted by a first for sliding gasket oilseal rings 16 in said ste guiding plate 7 and a second for sliding gasket oilseal ring 17-18 in said chamber partition septum. To the stem 15 is rigidly fixed, as for example shown in Figures 2 and 3 with the use of stopping ring means 19 of a third for sliding gasket oilseal ring means (e.g.0'RING)21 to relize a piston 20 slidable in the upper cavity or chamber partition 10 of the cylindre 3. The piston divides the upper cavity 10 into two chambers, respectively upward and downward chamber 22 and 23, of which both contain fluid, for example hydraulic oil, for which the shifting of the piston 20, and consequently of the stem 15, is possible only with the opening of appropriate valvular means allowing by holes 40,41 allowing the fluid to move from one chamber to the other and vice versa. Advantageously, as evidenced in the drawings 2 and 3, the valvular means are housed inside the hollow stem 15 advantageouuεly realized in tubular form 24 closed in correspondence of its own head 25, externally tapered by a holed cylindrical shutting element 26, fixed by a first elastic stopping ring 27 and, on the opposite side, by a cap 28 externally bulgy. The cap 28, which developes itself towards the inside of the stem 15, with its own stem 29 having a cylindrical end 30, is opportunately fixed to the tubular stem 24 by a second elastic stopping ring 31 and is equipped, in the bulgy space, of a first sealing ring 32. According to the invention, the valvular' means inside the stem 515, include a shutting block 33, svbstantially cylindrical, which presents, in its own lateral surface, a reduced upper area 34, placed between an upper edge 35 an a middle edge 35, and a reduce ' .lower area 37, placed between * tne middle edge 36 and a lower edge 38. 10 All three edges 35, 36 and 38 are equipped with suitable sealing εlidable gasket rings 39 sealing said reduced upper area e said reduced lower area 34,37 in correspondence of respective holes 40,41 allowing to pass the oil form -the upwards chamber -to -the downwards chamber and viceversa only if the reduced upper area 15 is placed between this ones (stem-rod 42-3 pushed down). More particularly, while the upper edge 35 moves, remaining however always above the first set of holes 40 and the lower edge 38 always below the second set of holes 41, the middle edge 36, in its movement, can overpass the second set of holes 41 2.0 shi ting above and unde . it. On one side of the block 33 is connected the stem-rod 42, coaxial to the stem 15, which protrudes with its own end 43 from the head 25; on the oppoεite εide of the block 33 act instead elastic means, advantageously constituted by a spiral spring ΛΔ 25 abuting -i -correspondent axial bulb-seat protrusion 45. The spirarl sring 44 is compreεεed between an axial protrusion 45 of the block 33 and a seat 46 opportunely obtained on the cylidrical end 30 of the cap 28. The spring 44 presses on the block 33 causing the upward 30 movement until the ,s * topping plate 47, eleεtically fixed in * to a suitable seat presentε in the upper portion of the internal stem-rod 42 efficiently constituent a checking element, goes to engage itself, with the interposition of a rubber ring 48, against the shutting cylindrical element 26; in this position, the middle edge 36 finds itself between the two sets of holes 40 and 41, while the upper edge 35 and the lower edge 38 find themselves respectively above the first set of holes 40 and below the second set of holes 41. Moreover it must be specified that in the cap 4 is present a threaded hole in which can opportunely be mounted a valve, or a shutting sealproof screw 49, which consents the filing of the lower cavity 11 with compressed gas, as for example compressed air; besides, in correspondence to the inside face of the cap 4 there is an end-stroke stopper 50, for example in rubber, which, at the total lowering of the εtem 15, engages itself with the cap 28. From what described, the functioning of the adjustable oleopneumatic support, according to the invention, appears evident and can be resumed in what follows. The lower base of cylindrical body 2 and the head 25 of the εtem 15 are respectively connected, exploiting opportunely the taper, to a basement 51 and to a seat 52 of a chair with central column, as shown simply as an example in drawing 4. In absence of action on the upper end 43, the " spring 44 maintains the stopping plate 47 engaged against the cylindrical shutting element 26, so that the shutter block 33 finds itself in a position correspondent to the positioning of its middle edge 36, between the two sets of holes 40 and 41; with the valvular means in this position no transvasing of oil can abviously occur between the two chambers 22 and 23 and the εtem 15 results blocked and able to support eventual loads acting on the seat 52 of the chair to which is applied (Fig.2). To modify the lenght of the adjuεtable oleopneumatic support and accoimpliεh the height adjuεtmentε of the seat 52 is sufficient to press down the upper end 43 of the inner stem-bar 42, compressing in this way the εpring 44 and moving the shutter 5 block 33 into the position shown in Figure 3 * in such position the recessed upper area 34 puts into co unication the two sets of holes 40 and 41, determining a circumferential passage that allows the " oil to flow from one to the other of the two upwards and downwards chambers 22 and 23, as shown by the arrows in the 10 drawing. If one desires to raise the seat 52, it iε sufficient to keep the end 43 pressed w±thTotit applying loads-to the chair until the stem lifts itself to the poεition desired, pushed by the action 15 exerted on the convex bottom of the cap 28 by the preεεure of the gas inside the lower cavity 11; if, vice versa, one wisheε to lower the seat 42, he muεt εimultaneouεly apply to the chair a light downwards puεh εufficient to win the modeεt gaε presεure to make the εtem 15 go down, inεide the lower cavity 11, aε much 20.aε desired. Accomplished the adjustment, releasing the end 43, the shutter block 33 returnε into the shutting position, blocking the stem 15 at the chosen height. 25 It is obvious that the presence of the upper edge 35 and the lower edge 38 prevent in every εitration the flow of the oil outεide; particularly the lower edge 38, maintains in any case, the area below the shutter block 33, clear, so that the lowering of the same shutter block 33 will not result contrasted by the 30 presence of oil and its-movement always smooth and the pruεh to apply to the end 43 alwayε of a modest intensity It has been so in practice verified that the application of loads, aven considerable, on the chair, is totally transferred from the piston 20 to the oil, which acts as sole supporting element. It is moreover evident that the gas which is inside the lower cavity 11, does not suffer in any way the applied load because it does not bear any supporting function but it is only used to supply the necesεary push to raise the seat during the adjustment; the pressure of the gas will be, for that reason, of a modest va±υe, with all the advantages that derive for what concerns leak proof, safety and reliability of the oleopneumatic εupport. The lower preεsures involved consent moreover to use a cylindrical body 2 of a bigger diameter, which associated with the particular stability of the stem 15, due to the movement through three guiding elements (holed plate 7, septum 12 and piston 20), allow the realization of supporting elements 1 that just by themselves have the necesεary εtability and lift force and make for that reason superfluous the use of auxiliary supporting elements of stabilizing shells. The invention so conceived is εusceptible of many modifications, all re-entering in the ambit of the inventive conception; so for example the valvular means might present modifications in comparison to those illustrated and different might be still the leak proof connections between the various elements and moreover all the details replaceable by other elements technically equivalent. In practice, the materials employed, provided they are compatible with the contingent use and dimensions, might be according to the demand and the technical state.

Claims: CLAIMS 1 An adjuεtable oleopneumatic support, particularly for chairε with central column, including a hollow cylindrical body (2), which lower base is rigidly linkable to the basement of a chair, and a coaxial stem (15) the head of which is rigidly linkable to the seat of said chair, being the second one leak proof axially slidable iside said cylindrical body (2), characterised in that: - said cylindrical body (2) compriseε inεide in an intemediate position a tranεverεal chamber anular partition εeptum (20) which εeparateε the interior of said cylindrical body in an upper cavity (22-23), developing itself in correspondence of said.upper base, and .n a lower cavity (11), developing itself on the other side; - εaid coaxial εtem (15) is hollow in cylindrical shape; - said hollow coaxial stem (15) being rigidly associated to a piston (21) which defines inside εaid upper cavity two chamberε, upawardε chamber and downwardε chamber reεpectively (22,23) both containing fluid; — said .hollow coaxial stem (15) being provided inside of valvular coaxial actuation means (33-43) controlling a passageway oil means (40,41) the respective outlets being placed upwards and downwardε the piεton (20) respectevely; - said lower cavity (11) being able to contain compresεed gaε. mλ. An .adjuεtable oleopneumatic support, according to the claim 1, characterised in that said oil paεεageway with valvular meanε (33) includeε a mobile εhutter block (35) εlidable inεide said coaxial stem (15) presenting, in its own lateral εurface, at last in one εhifted poεition a first reduced anular area (34) connecting said two opposed outlet oil paεεageway meanε (40-41) to link the oppoεed chamberε, and in the opposed shifted position interdiction of said oil paεsageway. 3. Adjustable oleopneumatic support, according to the claim 2, characterised in that said shutter block (35) presents a second reduced anular area (37) adjacent to εaid first reduced area (34), said reduced areas being separated one from the other by a 5 middle circumferential edge (36) and delimiteted externally by outer circumferential edges (35,38), said middle edge and said outer edges coupling themselves fluently, hydraulic seal (39), with the interior wall of said stem (15). 104. An adjustable oleopneumatic support, according to the preceding claim, characterised in that said outer circumferential edges (35,38), are spaced in order to coprise said two opposed outlet oil passageway meanε (40-41). 155. An adjustable oleopneumatic support, according to claim 2., characterised in that said shutter block (35) is connected to a coaxial stem-bar (42) substantially upper protruding (43) from the head of said hollow coaxial stem (15), allowing to move downwards the shutter block (35), being said first reduced 0 anular area (34) placed in upper position to allow interconnection free oil passage between said upwards and downwards opposed chambers (22-23). 6. An adjustable oleopneumatic support, according to claim 2., 5 characterised in that under εaid shutter block (35) elastic means (44) pushing the shutter block (35) upwards are provided. 7. An adjustable oleopneumatic support, according to claim 2., characterised in that said lower cavity (11) in said cylindrical 0 body (2) presents, in correspondence with its own lower base (4), an occludable hole (49) for the filling of said lower cavity with said gas. 8. An ad uεtable oleopneumatic εupport, according to claim 2., characterised in that εaid lower cavity (11) in εaid cylindrical body (2) presents, inside in correspondence with itε own lower baεe (4), an elastic rubber abutment "means (50) to stop the downwards shifting of the respective said hollow coaxial stem (15).

Inventors: MARDOLLO SCIPIONE, MARDOLLO, SCIPIONE
Applicants: LIFTER SRL, LIFTER S.R.L.
Application year: 1987
Main classification: A47C3
IPC codes: A47C3