US 3858935 A
The present invention relates to a chair, for example an office chair for typists, which comprises a seat part, a back rest part, and an adjustment mechanism associated with each part adapted to permit relative adjustment between the parts and a pillar arrangement interconnecting the parts, the seat and backrest parts each being of hollow monocoque form and defining a cavity within which the associated adjustment mechanism is located and concealed.
Claims available in
Description (OCR text may contain errors)
United States Patent 1191' lPask 1 Jan. 7, 1975  IR 3,526,430 9/1970 Eldon 297/353 3,539,142 11/1970 Morand 248/410 x  Inventor i:; 3,722,954 3/1973 Rey et a1 297/452  Filed Oct 24 1 FOREIGN PATENTS OR APPLICATIONS  Foreign Application Priority Data Assistant Examiner-Williamli. Lyddane Oct. 22, 1971 Great Britain 49289/71 Attorney Agent & Kruger  US. Cl 297/353, 248/410, 297/383  ABSTRACT  Int. Cl. A47c 3/00 The 9 present InventIon relates to a chaIr, for example [5 8] held of Search d ig f glg fi an office chair for typists, which comprises a seat part,
l a back rest part, and an adjustment mechanism associated with each part adapted to permit relative adjust-  References C'ted ment between the parts and a pillar arrangement inter- UNITED STATES PATENTS connecting the parts, the seat and backrest parts each 2,281,038 4/1942 Jones 297/353 being of hollow monocoque form and defining a cavity 2,662,586 12/1953 am 297/383 X within which the associated adjustment mechanismis Fisher X located and concealed 3,115,368 12/1963 Springer et al. 297/451 3,173,723 3/1965 Hoven et a1. 297/451 12 Claims, 4 Drawing Figures 13a 14a ,3 id v i o 6a 4a L IF 1 l [V i IT/ ====1 1 3 7c 1 HA 11 A I 15 12 24a 1 1.- 1 2 5 2.3 A 9 :25 A
C H a H 9], H 0 11 i? Appl. No.: 299,904
5/1962 Great Britain 297/455 Primary Examiner-Paul R. Gilliam PATENTEU JAN 7 I975 SHEET 2 [IF 2 CHAIR The present invention relates to chairs, and in particular to adjustable commercial, contract or industrial chairs, for example, typists chairs or the like.
Such chairs usually incorporate a seat part, a backrest part, and an adjustment mechanism by means of which the position of the backrest part may be adjusted and locked relative to the seat part. Heretofore, the ad justment mechanism has been external and exposed, so that it is visible and detracts fromthe general appearance of the chair.
From one aspect, the present invention consists in a chair comprising a seat part, a backrest part, and an adjustment mechanism to permit relative adjustment between the parts, at least one of said parts defining a cavity within which at least a major proportion of the ad justment mechanism is located and concealed.
From another aspect, the invention consists in a chair including a seat part having a transversely extending support surface at least partly bounded by aperipheral rim formed therein with at least one laterally outwardly opening recess arranged to receive an anchor member associated with'a seat cover when the seat cover is assembled to the seat part, to retain the cover secured to the seat part.
The invention also consists in a chair or seat having a hollow seat part formed from two shell-like mouldings of synthetic plastics material, secured together and formed, internally of the seat part, with ribs.
In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which:
FIG. 1 is a plan view of a seat part of a typists chair embodying the invention, prior to assembly of the top moulding of the seat part;
FIG. 2 is a vertical section through the typists chair, on the line A-A of FIG. 1, after assembly of the top moulding, and with the backrest part omitted;
FIG. 3 is a section on the line B-B of FIG. 1 after assembly of the top moulding; and
FIG. 4 is a vertical section through the backrest part of the chair shown inFIGS. l to 3.
Referring to the drawings, the chair basically comprises a seat part 1 carried by a pedestal 2, a backrest part 3 (FIG. 4) attached by a double pillar arrangement 4 to the seat part 1, and armrest parts 5 (FIG. 2) secured to the seat part by pillars 6. The seat, backrest,
and armrest parts 1, 3 and 5 are moulded from a syn-- thetic plastics material, for example, from a high impact polystyrene such as acrylonitrile-butadienestyrene, whilst the pillars 4 and 6 are formed from metal tubes, for example, circular section, chromiumplated, mild steel tubing, or stainless steel tubing.
The pillars 4 are both bent from a common length of tubing folded back onto itself, the U-fold joining the pillars being located within the backrest part 3. The pillars 4 are mutually parallel and, intermediate their opposite ends which extend into the parts 1 and 3, are
curved as shown in FIG. 4. Both the seat part 1 and the backrest part incorporate an adjustment mechanism, which will be described hereinafter, to permit sliding adjustment to be effected between the upper generally upright ends of the pillars 4 and the backrest part 3, and between the generally horizontally extending lower ends 4a of the pillars 4 and the seat part I.
Referring to FIGS. 2 and 3, it will be seen that the seat part 1 comprises a bottom shell or moulding 7 and a top shell or moulding 8, each comprising an expansive surface bounded by peripheral rim flanges 7a and 80 respectively. The mouldings, when secured together, define therebetween a cavity within which an adjustment mechanism, indicated generally at 9, is mounted. The bottom moulding 7 is provided with a pair. of circular openings 7b (FIG. I) in the rear part of the rim flange 7a, spaced apart by a distance equal to the distance between the lower ends 4a of the pillars 4. The expansive surfaces of the top and bottom mouldings are formed with pairs of parallel internal longitudinal ribs 10 and 11 respectively :in alignment with the openings 7b, the ribs of the top and bottom parts being spaced apart vertically, as shown in FIG. 3, so as to define two parallel guide channels 12 for slidably receiving the lower, horizontally extending, parallel ends 4a when inserted through the openings 7b. The ends of the ribs 10 and '11 adjacent the openings 7b are relieved as shown at 100 and 11a to facilitate'insertion of the lower ends 4a into their respective channels 12.
Referring in particular to FIG. 1, the adjustment mechanism 9 includes a wedging element comprising a pair of substantially rigid, cranked strips 9a, formed for example from steel or spring steel plates. The adjacent or inner ends of the strips 9a are provided with cutaway s or semi-circular recesses which engage in an annular channel 9b in acylindrical push button formed, for example, from a synthetic plastics material. The opposite or outer ends of the strips are rockably located in slots 13a in ribs 13 integral with the bottom moulding 7.
An opening 9d is formed in each strip, each aligned with its associated channel 12, and being slightly larger in diameter than the external diameter of the pillars 4. To prevent the strips'9a from becoming inadvertently separated from the push button 9c in the absence of the pillars 4, each strip is provided with a raised shoulder 9e which is engageable with an adjacent inner rib ltlof the top moulding.
The push button 90 includes an outer manually depressible part which projects through an opening 7c in the rim flange of the bottom moulding 7. The push button also includes an inner reduced diameter guide part 9f surrounded by a compression spring 14, one end of the spring being located against a shoulder of the push button adjacent the annular channel 9b, and the other end of the spring being located against a washer which abuts a transverse rib 15 formed integrally with the bottom moulding. The reduced, diameter part of the push button extends through a guide aperture in the rib l5, and is fitted with a retainer, such. as a circlip 9g which serves to limit the extent of the sliding displacement of the push button under the action of the spring 14.
It will thus be apparent that, in the free state of the adjustment mechanism, the spring 14 tends to urge the push button, and the inner ends of the strips 9a, rearwardly, thus increasing the inclination of the outer cranked ends of the strips relative to the transverse plane of the channels 12. By manually depressing the push button against the action of the spring, the strips are rocked-about the slotted ribs 13 reducing the inclination of the said outer ends.
. The adjustment mechanism just described possesses the advantage that the strips 9a are, to a certain extent, free to move toward and away from each other upon tively locate, but permit horizontal sliding movement of, the ends 4a of the pillars. Upon release of the push button, the inclination of the outer ends of the strips is increased by the action of the spring 14, causing the sides of the openings 9d in these ends to wedgingly engage the lower ends 4a of the pillars, thus preventing unintentional displacementof the pillars 4 relative to the seat part 1. When it is desired to adjust the position of the pillars, and therefore the backrest part, relative to the seat part, the button 9c is depressed to unlock the pillars.
It will be apparent from FIGS. 1, 2 and 3 that the top and bottom mouldings 7 and 8 are provided with numerous additional internal integral ribs to stiffen and strengthen the seat part and to enable its connection to the pedestalj2. The peripheral rim flanges 7a and 8a of the mouldings, when assembled together, define an outwardly opening, laterally extending recess 16.
Referring now to FIG. 4, the backrest part 3 is of sim- When the arm rests are provided, the tube portion 6a is additionally secured to the seat top moulding by screws 25c which extend downwardly through pillars 8b and are threaded into apertures 6b in the tube portion 6a rearwardly of stirrups 24b. The rear zones of the seat top and bottom mouldings are thus interconnected via the tube portion 6a, whilst the mouldings are also secured together'at other zones by suitable means, such as further screws. When the top and bottom mouldings are thus secured together, they form a very strong and rigid box or monocoque structure, and by virtue of the previously described anchorage of the tube portion 6a any tendency for the tube portion 6a to distort or crack the seat mouldings, when loads are placed on the arm rest parts during normal use of the chair, is reduced or eliminated.
ilar basic construction to the seat part l,'and will not,
therefore, be described in detail.
Briefly, the backrest part comprises front and rear mouldings 17 and -18, provided with pairs of parallel ribs 19 and 20 forming guide channels for the pillars 4, and with an adjustment mechanism 21 equivalent to the mechanism 9. Since the pillars 4 are, as previously mentioned, joined by a U-fold located within the backrest part, the rib portions 20a and the opposed portions of the ribs 19 are reduced in height on the side of the transverse rib 22 remote from the adjustment mechanism to accommodate the said fold without inhibiting the sliding movement of the pillars 4 within the channels between the ribs 19 and 201. i
The backrest part 3 also includes a peripheral outwardly opening and laterally extending recess23, similar to the recess 16 of the seat part.
Referring to FIG. 2, the arm rest parts 5 are of similar 2-part construction to the backrest and seat parts, although they do not incorporate any adjustment mechanisms equivalent to the mechanisms 9 or 21.Each arm rest part receives and is secured to a flattened generally horizontal upper end of pillar 6 formed from a single length of tube. The central lower V-shaped portion 6a (FIG. 1) of the tube is located in stirrups 24a and 24b, integral with the internal surface of the seat bottom moulding 7, prior to assembly of the seat top moulding, and is securely held in place by the latter and by screws 25a, 25b. The tube portion 6a is inclined downwardly towards the front of the seat part, as clearly shown in HO. 2, so that, adjacent the stirrup 240 this portion 6a will be disposed below the horizontally extending lower ends 4a of the pillar 4, whilst the depth of the slots 7d in the seat bottom moulding peripheral rim flange 7a, through which the tube portion 6a passes, will be minimised. The slots 7d may be produced by breaking away weakened portions of the flange 7a, these portions being left in tact to eliminate the slots in the chair if the chair is, alternatively, not to be provided with armrests.
The provision of the outwardly opening peripheral recesses 16 and 23 in the seat and back rest parts, and corresponding recesses in the arm rest parts, serve to enable upholstery to be readily attached to some or all of the various parts if requiredfFor example, as shown in FIG. 2, the seat part is provided with an upholstery cover 26 having a beading containing an elastic anchor member, such as a helical spring wire loop 26a which is stretched overthe flange 7a and snaps into the recess 16, thus holdingthe cover firmly anchored to the seat part. A layer of padding 26b, such as a layer of resilient foam or other upholstery material, may be located between the seat part and the cover, retained in place by the latter. Upholstery may thereby be rapidly and simply'attached to the seat part and removed and-replaced if necessary. The backrest and arm rest parts may be upholstered in a similar manner.
From the foregoing description, itwill be seen that there is provided a particularly advantageous design of adjustablechair embodying hollow rigid monocoque seat and backrest partswithin which are substantially entirely mounted, andconcealed, adjustment mechanisms by means of which the position of the backrest part, and the seat rest-part, relative to the pillars 4, may be easilyand efficiently slidably adjusted, and positively locked in any desired adjusted position. The adjustment mechanisms incorporate the minimum of components, are reliable and simple, and may be readily assembled during manufacture of the seat. Furthermore, due, to the particular configuration of the backrest supporting pillars, for the purposes of storage or transport, the bulk of the chair may be substantially reduced by withdrawing these pillars from the seat part, inverting the pillars so that the backrest part extends downwardly, and reinserting the pillars so that the backrest part is nested adjacent the chair pedestal.
It will be understood the various modifications may be made without departing from the scope of the present invention. For example, the strips forming part of the adjustment mechanism 9 in the seat part and/or the equivalent strips in the backrest part, may be formed from synthetic plastics material or other rigid, resilient or flexible material, instead of from metal. The strips may be straight instead of cranked, and may be joined together, and/or to the push button, for example by a hinge or hinges. The strips may be moulded integrally with the push button when the button and strips are formed from a plastics material. Alternatively, the or each adjustment mechanism may be replaced by other forms of mechanism located within a cavity or recess in the seat and/or backrest part, for example by a ratchet and pawl mechanism. The arm rest and/or seat part may incorporate adjustment mechanisms to permit adjustment of the arm rest parts. Alternatively, some or all of the adjustment mechanisms may be omitted.
From a consideration of the various adjustment mechanisms shown, it will be seen that the locking or wedging force exerted by the inclined strips of the mechanisms will tend to increase upon application of a force tending to press the pillars further into the seat or backrest parts, but will tend to decrease upon application of a force tending to withdrawn the pillars from the seat or backrest parts. To minimise the possibility of unintentional withdrawal of the pillars relative to, and possibly completely from, the seat part, for example if the chair is lifted by the pillars, the spring 14 should be as strong as possible, consistent with ease of operation of the adjustment mechanism. To facilitate operation of the adjustment mechanism particularly if a spring is employed which could not easily be compressed by direct manual pressure on the push button, the push button or its equivalent may be positioned internally of the seat part, and may be actuated indirectly by a system possessing improved mechanical advantage, such as a lever system, or rotary or sliding cams operable by a rotatable external knob or lever. For example, a rotatable knob may have an inwardly directed inclined cam surface cooperable with an oppositely inclined cam surface of the push button or equivalent.
The withdrawal of the pillars relative to the backrest part may be used to advantage, for example by employing in its adjustment mechanism a sufficiently weak spring (corresponding to the spring 14) to enable the backrest part to be drawn up the pillars for height adjustment purposes without depressing the associated push button. In this event a tension spring may be connected to the U-fold or equivalent member joining the pillars 4 within the backrest part, and to an internal part of the backrest part adjacent the top thereof, i.e. remote from the adjustment mechanism, which tension spring will tend to bias the backrest part downwardly on the pillars and supplement the weak locking action created by the adjustment mechanism spring. Thus, the
backrest part will, in spite of this weak locking action,
not move up the pillars unless positively raised, and will not move down the pillars unless the push button is depressed. Alternatively, the said additional tension spring may be connected between the U-fold or equivalent and a point within the backrest part adjacent the adjustment mechanism so as to assist upward adjustment of the backrest part on the pillars.
The seat and/or backrest and/or arm rest parts may be formed from plastics materials other than acrylonitrile butadiene-styrene, or may be cast from metal, for example a light metal as alloy such as aluminium alloy.
The adjustment means, and the method of attachment of the covers are not restricted to chairs or seats, such as contract, domestic, industrial or commercial chairs or seats, and may be applied to other furniture.
1. A chair including a seat part and a backrest part, both said seat part and said backrest part being formed from two shell-like mouldings of synthetic plastics material, each shell-like moulding comprising an expansive surface at least partly bounded by a peripheral rim portion, the mouldings being secured together with their rim portions directed towards each other to form a cavity therebetween, the chair further including a pillar arrangement supporting the backrest part fromthe seat part, and having a generally upright portion extending into the cavity within the backrest part and cooperating directly with the shell-like mouldings of said part to permit sliding adjustment of said backrest part relative to the upright'portion in the longitudinal direction of the upright portion, a first adjustment mechanism located and substantially entirely concealed within the cavity in the backrest part, enclosed by the expansive surfaces of the two-shell-like mouldings of said part, and carried directly by the shell-like mouldings of said part, said mechanism being releasably cooperable with said upright portion to lock the backrest part in selected adjusted positions relative to the upright portion, the pillar arrangement also having a generally horizontal portion extending into the cavity within the seat part and cooperating directly with the shell-like mouldings of the seat part to permit sliding adjustment of the horizontal portion relative to the seat part in the longitudinal direction of the horizontal portion, and a second adjustment mechanism located and substantially entirely concealed within the cavity in the seat part, enclosed by the expansive surfaces of the two shell-like mouldings of the seat part, and carried directly by the shell-like mouldings of the seat part, said second adjustment mechanism being releasably cooperable with said horizontal portion to lock the latter in selected adjusted positions relative to the seat part.
2. A chair as claimed in claim 1, wherein the shelllike mouldings of each part are fbrmed within the associated cavity with a plurality of ribs which stiffen the shell-like mouldings, at least some of said ribs slidably supporting, guiding and locating the associated portion of the pillar arrangement.
3. A chair as claimed in claim 2, wherein the first and second adjustment mechanisms are substantially identical, and each adjustment mechanism is located and supported within itsassociated part by cooperation with internal members integral with the shell-like mouldings of its associated part.
4. A chair as claimed in claim 3, wherein each adjustment mechanism includes an element wedgingly coop erable with the pillar arrangement within the cavity in the'associated part, to normally lock the pillar arrange ment against sliding movement relative to said associated part, the mechanism further including a manually actuable member disposed externally of said associated part and being cooperable with the wedging element upon manual actuation ofsaid member to displace the wedging element to a position in which its wedging action on the pillar arrangement is released, said member being the sole component of the mechanism not concealed within the cavity.
5. A chair as claimed in claim 4, wherein the pillar arrangement comprises two transversely spaced, genen ally parallel, tube portions interconnected within the backrest part, the tube portions slidably extending through openings in the rim portion of one moulding of each of the seat and backrest parts and through aligned openings in the wedging element of the associated adjustment mechanism, said wedging element being dis placeable, upon manual actuation of said member, from a wedging position in which the plane of each opening in the element is inclined with respect to a transverse plane of the associated tube portion and the edge of the opening wedgingly cooperates with the said tube portion, to a non-wedging position in which the inclination of the plane of said opening with respect to the transverse plane of said tube portion is reduced.
6. A chair as claimed in claim 5, wherein the wedging element of each adjustment mechanism comprises a pair of rigid plate-like strips, the two strips having inner mutually adjacent ends cooperating with the manually actuable member, and outer ends spaced from said inner ends, each of said outer ends being provided with one of said openings, the strips being mounted within the cavity in the associated part for rocking movement about an axis disposed generally normal to the direction of relative sliding movement between the associated part and tube portions.
7. A chair as claimed in claim 6, wherein the manually actuable member comprises one end of a push button mounted in the associated part for sliding movement generally parallel to the direction of relative sliding movement between the pillar arrangement and said associated part, the head projecting through an opening in the rim portion of the moulding and disposed centrally between the openings therein which receive the tube portions of the pillar arrangement, and the push button being spring biased towards a position, corresponding to the wedging position of the wedging element, in which the head extends from its opening, and wherein the inner ends of the strips are cooperable within a recess in the push button, each strip being rockably mounted in a slot in a rib formed within the associatedcavity at a position spaced from the inner end of that strip by the opening therein.
8. A chair as claimed in claim 4, wherein each wedging element is formed from metal, and, when in its 8 wedging position, is operable to positively lock the pillar arrangement against sliding movement in a direction into the associated part whilst permitting sliding movement in the reverse direction.
9. A chair as claimed in claim 1, wherein the shelllike mouldings of each part are formed within the associated cavity with pairs of parallel opposed ribs which define therebetween longitudinal channels which guide and locate the pillar arrangement relative to the part.
10. A chair as claimed in claim 1, including armrest parts mounted on tubular pillars, the lower ends of which project generally horizontally into the cavity within the seat part mouldings through a rim portion thereof, each lower end being secured to the uppermost of the seat part mouldings at a position adjacent the rim portion thereof, and to the lowermost of the mouldings'at a position spaced along said lower end from the rim portion by the first mentioned position.
11. A chair as claimed in claim 1, wherein at least the seat part is formed with a peripheral laterally outwardly opening recess, and the seat part is fitted with an upholstery cover including an anchor member which is enand seat part.