US 3899207 A
Description (OCR text may contain errors)
United States Patent 1191 Miieller CHAIRS  Inventor: Falk Mueller,Tauberbischofsheim,
Germany  Assignee: VS-Schulmoebel Verwaltungs-Gmbli, Germany  Filed: Dec. 28, 1973  Appl. No.1 429,626
 lForeign Application Priority Data Dec. 20, 1972 Germany 465033[U]  US. Cl 1. 297/239; 297/445  int. Cl. A47C 3/04  Field of Search 297/239, 452, 442, 445, 297/331, 336, 446, 448; 108/91; 248/1889  References Cited UNITED STATES PATENTS 3,159,428 12/1964 Schier 297/239 x 3,203,731 8/1965 Krueger 1 1 297/239 3,236,559 2/1966 Kaufman 297/239 [llllllllllllllllllllllllTlj 1 Aug. 12, 1975 3,734,561 5/1973 Barecki 297/239 3,796,169 3/1974 Bales et a1. 108/91 X FOREIGN PATENTS OR APPLICATIONS 342,710 1/1960 Switzerland 297/239 524,397 8/1940 United Kingdom 297/239 602,218 5/1948 United Kingdom 297/239 Primary ExaminerFranCis K. Zugel Attorney, Agent, or Firm-Brumbaugh, Graves, Donohue & Raymond  ABSTRACT A staclcable chair has a frame which comprises a U- shaped base, open to the front and two lateral supports welded or otherwise secured to the limbs of the base and upstanding therefrom. A seat is attached to a U-shaped seat supporting frame, open to the rear, which is welded or otherwise secured to the supports. A back rest is attached to the upper ends of the supports. The seat and/or the back rest may comprise a blow moulded hollow body.
23 Claims, 7 Drawing Figures PATENTED AUG 1 2 I975 SHEET PATENTED AUG 1 2 I975 SHEET PATENTEDAUB 1 2197s 3, 899.207
y ll -I CHAIRS The invention relates to stackable chairs.
One previously proposed stackable chair has a base formed by two side runners which are joined together in the form of an H. Upstanding lateral supports for the seat and the backrest are outwardly secured to the runners. Thus the connections between the supports and the runners are liable to bend when the chair is tilted on edge. The central part of the H also reduces leg movement. The supports and the central part connecting them comprise separate parts so that a very large number of points of welding is required, or very sharp bending is needed and this precludes the use of tubing or hollow profiles for the manufacturing material.
Another previously proposed stackable chair has a U-shaped base lying on the floor and comprise a single U-shaped piece of steel tubing which is closed at the rear and from the front ends of which two lateral supports are bent upwardly to the two front corners of the seat, pass beneath the seat and in turn are bent upwardly in the rear region to form a support for the back rest.
An advantage of this chair in fact is that its frame can be bent substantially from one piece of tubing without much welding, but it needs a relatively large quantity of material because, on the one hand, the length of its tubing is relatively long and, on the other hand, the tubing must have a very large cross-section or a high quality. The weight of the person using the chair is in fact largely concentrated to the rear portion of the chair, i.e. in precisely that portion where there is no support, and consequently the whole chair is compressed like a spring.
A feature of the invention is, therefore, to produce a a stackable chair on runners which keeps its shape whilst not requiring much material and can be produced simply.
According to the invention, a stackable chair comprises a metal frame having a continuous U-shaped base and two lateral supports which slope backwards and are outwardly attached to the central regions of the two substantially parallel runners formed by the limbs of the U-shaped continuous base which is open at the front and is closed at the rear by a crosspiece, a seat having a U-shaped seat supporting frame attached to the supports, said seat supporting frame being closed at the front and extending round the peripheral region of the seat, and a back rest attached to the upper ends of the supports.
It should be recognised that such a chair needs only four parts for its frame, i.e. the two substantially straight or slightly curved lateral supports and two U- shaped frames. The two U-shaped frames which are preferably welded between the supports create a very sturdy, self-supporting frame to be produced which is very resistant to twisting or buckling especially because of the frame arrangement which is closed at the front at the seat and is closed at the rear at the base. The chair can be readily stacked and saves a great deal of space. Compared with the previous proposal wherein the supports were produced integrally with the base and, by bending, were converted into a section running forwards parallel to the limbs, considerably less and more simple bending is necessary and consequently harder materials may be used.
In one preferred embodiment of the invention the front ends of the limbs of the base are closed by closure members having a lower supporting face. The frame is made preferably from substantially flat oval tubing. What is also meant hereby is a tubing whose crosssectional form consists of two semi-circular arcs and straight lines connecting these arcs. The flat oval tubing has the advantage of being very resistent to bending in the main bending direction which corresponds to the alignment of the flat oval tubing, i.e. in the longitudinal direction of the chair in the case of the supports and in the vertical direction in the case of the base.
in the preferred embodiment of the invention, the two supports in the region of the seat are joined together by means of a seat supporting frame to which the seat is attached and which passes below the seat. This seat supporting frame is preferably welded to the supports and thus serves to achieve a very sturdy chair. It also enables the seat to be made from a less rigid, i.e. not necessarily self-supporting material.
The seat supporting frame may preferably pass round the outer edge of the seat and project a little beyond this outer edge. Besides giving the chair a very good appearance, this frame also protects the material of the seat which is generally made of a softer and less robust material. However, the person using the chair does not normally feel the edge of the seat supporting frame, which only projects a few millimeters, whilst he is sitting.
The seat supporting frame may be made of a metal profile whose underside is constructed so as to accommodate a protective profiled strip made of a resilient adherent material. The structure of the seat supporting frame will preferably be a closed or open square structure. The underside of the seat supporting frame may have an undercut structure which is highly suitable for inserting and holding the protective profiled strip.
The seat and/or the back rest may be made from a hollow body of plastics material. This can be made relatively easily as a substantially closed body by a blow moulding process. It is very sturdy and the parts which are in contact with the occupants body have a relatively small mass so that it does not feed cold. A substantial advantage lies in the fact that the underside of the chair is also closed.
Such a seat may have a recess formed in the region of its outer edge, this recess being so constructed that it at least partially accommodates the seat supporting frame. It is also possible to give the wall forming the underside of the hollow seat a reinforcing structure which, if need be, provides direct support for a load applied to the top of the seat.
The same advantages are produced when the back rest is constructed as a hollow body made of plastics material. It is important for the back wall of the back rest to also be closed, thus giving a very good appearance without the chair becoming heavy thereby. The back rest can advantageously be inserted between the upper ends of the supports, but may also overlap these supports.
A handle-type recess, which does not go through the rear wall of the hollow back rest, may be formed in this wall. This handle-type recess which is important for carrying the chair does not therefore need to be obtained at the expense of an inconvenient cut in the back rest.
The invention is further described, by way of example, with reference to the accompanying drawings, in which:
FIG. i is a perspective view of a chair according to the invention FIG. 2 is a fragmented section along line II-II in FIG. i to a much larger scale.
FIG. 3 is a likewise fragmented section along the line lIl-IIl in FIG. 1, also on a larger scale,
FIG. i is a side view of chairs which have been stacked one on top of the other according to a modified embodiment of the invention.
FIG. 5 is a side view of a chair with the underside of the suspended on a table,
FIG. 6 is a front view of the chair of FIGS. 4 and 5.,
FIG. 7 is a sectional detail of a front or side edge of the seat of the chair of FIGS. 4 to 6.
The chair ii shown in FIGS. i to 3 has a frame 112 made of steel tubing, i.e. from flat oval-sectioned tub ing. The cross-section of this tubing comprises two semicircular arcs and straight lines connnecting these arcs. The frame 12 has a U-shaped base i3 comprising two lateral runners 14, which extend substantially in the longitudinal direction (forwards and backwards) of the chair, and a rear crosspiece 15 which joins the two runners 14 together. The U-shaped base 13 thus formed is curved integrally with relatively large rounded portions at the corners and is open at the front. The front ends are closed by closure members 16 of plastics material which are slipped over the free ends of the runners i4. They also have on their underside a supporting face 17 which serves as a foot to protect the floor from being damaged. Large supporting members 18 are situated in the region of the rear corners. In particular, both these supporting members serve to protect carpeted floors.
The frame 12 also has two lateral upright supports 19 whose lower ends are outwardly joined to the central region (a little in front of the middle) of the runners 114. The joints are thereby subjected to a relatively small leverage. The joints are made by welds 20. The substantially straight, but in the embodiment shown in PEG. 1 slightly forwardly curved supports 19 are welded on to the base frame so that they slope upwardly rearwards. During attachment it should be ensured that the supports 19 are attached to the runners i from the outside in such a way that the base of a chair which is stacked on top can pass between the supports as shown in FIG. 4. If need be, it may therefore be advisable to provide a small intermediate layer between the support 19 and base runner 14 before welding or to weld the support and the base runner together so that there is a gap therebetween. This object can also be achieved, however, by reducing the space between the runners i4 rearwardly of the base 13.
At seat level the supports 1? are joined together by means of a U-shaped seat supporting frame 21 which is closed at the front and open at the rear. This seat supporting frame extends round the outside of a seat 22 and projects a little outwardly of the seat 22. The seat supporting frame 21 is inserted between the supports 19 and connected to these supports by welds 23. It is also important here for the seat of a chair to be able to slide between the supports of an identical chair during stacking.
As can be seen from FIG. 2 the seat supporting frame 21 is made of rectangular section steel tubing which is bent into its U-shape.
The seat 22 is a hollow member made of plastics material which is substantially closed on all sides and is manufactured by a blow moulding process. It has an upper side 24 serving as a seat face and an underside 25 provided with channel like indentations 26 which form a structure to reinforce the underside of the seat. As can be seen, there is only a relatively small gap between the upper side E i and the base of the indentation 2n and this gap can be closed upon deflection of the seat upper side 24 so that the underside then carries part of the weight of the person using the chair. The seat can be very well adapted to this seat form during manufacture. In the region which is enclosed by the seat supporting frame Iii, the periphery of the seat has a recess 27 which is partially adapted to the outer structural form of the scat supporting frame 211 which is rectangular in the present embodiment. A continuous projection 28 on the seat 22 engages beneath the lower face of the seat. supporting frame 21 so that the seat can be slipped from the rear into the seat supporting frame and be guided therein. A sloping stop projection (not shown) may be moulded on a surface of the seat 22 which is in contact with the seat supporting frame 21, this stop projection engaging with a hole in the seat supporting frame and securing the seat in position.
In the peripheral region of the underside 25 of the seat, recesses 29 are formed in which resilient supporting pads 36) can be inserted. These recesses may alternatively be moulded in so that they extend round the underside of the seat and can receive profiled padding. These supporting pads 3d serve to protect the seat face during stacking (cf. FIG. 4) and to protect a table face when the chair is possibly and advantageously suspended on the table whilst the floor is being cleaned, or during a similar process, (of. Fi'G. 5). On advantage of the chair according to the invention is that this type of chair suspension is possibie.
A back rest 31 is also made of a hollow body of plastics material which is manufactured by a blow moulding process. This body is also substantially closed on all sides. FIG. 3 is a central cross-section through the back rest 31.. It is inserted internally between the supports i9. The back rest 33 is secured by means of screws 33. The hollow body may alternatively be of such a shape that it overiaps the upper ends of the supports 29. in the present embodiment, the upper ends of the sup' ports 19 are closed by end pieces 34. The back rest 31 is not thicker than the dimensions of the supports 19 in this direction, its. the longitudinal direction of the chair. It is thereby ensured that the chairs are parallel to each other during stacking and are not pushed forwards like a fan as a result of a thickened or screwedon back rest.
in the rear wali 35 remote from the person using the chair, a handlelike recess 36 is provided, but this does not impair the closed form of the hollow space and the back support face.
FIG. 4 shows principally the advantageous manner of stacking chairs according to the invention. Because the supports 19 are externally located and there is room for the bases 13 and the seats between the supports ilQ, the chairs can be stacked very compactly and very sturdiiy. Because of the substantial paralielism between the upper and lower faces of the seat, a straight stack is formed which does not tilt forwards, as would be the case with sloping undersides for the seats.
The embodiment shown in FIGS. 4 to 7 differs from that shown in FIGS. 1 to 3 in that the supports 19 are completely rectilinear and in that seats 22' made of shaped plywood are used instead of seats made of hollow pieces of plastics material as illustrated particularly in FIGS. 2 and 3. The seat supporting frame 21 which is used thereby, is shown in detail in FIG. 7. It consists of an open steel structure forming an angle with an upper limb and a front limb to which a U-shaped structure 40, which is open towards the bottom but which is slightly undercut, is connected on the underside. A resilient profiled strip 30 of plastics material which serves as a supporting pad is inserted in this U-shaped structure. The seat 22 is made of pre-formed plywood and is connected to the seat supporting frame 21' by means of screws or rivets 37. This seat supporting frame may have the most varied shapes and in particular a closed structure can also be used or a C-shaped structure wherein the structure 30' is inserted in its lower opening.
The seat supporting frame may also have the form of an angular frame which is open towards the top and into which an upholstered seat may be inserted or pushed in from the rear. The cushion can be prevented from falling out by screws, but the entire seat load is transferred directly from the seat to the lower horizontal members of the angular frame. The angular frame may become flatter towards the front from its mounting point to the supports so that there is also an adequate amount of upholstery in the edge region and a person does not sit on the high edge of the angular frame when the upholstery is compressed.
The U-shaped seat supporting frame and the U- shaped base should, in the region of their curves have smaller dimensions between the limbs (in the case of the seat supporting frame) and between the runners (in the case of the base) than at the ends remote from their curves. These ends then slightly diverge in the direction of their free ends in the case of the base or in the direction of their welded ends in the case of the seat supporting frame. This makes stacking easier and also enables, if necessary, the supports to be formed so that they slightly converge towards the top, this possibly being desirable from the point of view of appearance and statics.
1. A stackable chair comprising:
a. a continuous U-shaped metal base having a pair of substantially parallel runners, said U-shaped base being open toward the front of the chair;
b. a pair of lateral supports attached to the outer sides of the central portions of said runners and sloping upwardly towards the rear of the chair;
0. a U-shaped metal seat support attached to said lat- V eral supports, said seat support being open toward the rear of the chair;
d. a seat attached to and peripherally surrounded by said seat support; and
e. a back rest attached to said lateral supports above said seat support.
2. A chair according to claim 1, in which said means attaching said supports to said base and to said seat supporting frame comprises welding.
3. A chair according to claim 1 in which said base and said supports comprise metal tubing.
4. A chair according to claim 3 further comprising closure members closing the front ends of the runners formed by said limbs of the base, each of said closure members being provided with a lower supporting face.
5. A chair according to claim 3 in which said frame is made essentially from flat oval tubing.
6. A chair according to claim 1 in which said seat supporting frame passes around the outer edge of said seat and projects a little beyond such outer edge.
7. A chair according to claim 1 in which said seat supporting frame comprises metal tubing.
8. A chair according to claim 1, in which said seat supporting frame comprises a bent metal profiled bar whose underside is provided with means for accommodating a protective profiled strip of resilient material, and in which a strip of resilient profiled material is received in the last mentioned means.
9. A chair according to claim 8, in which the last mentioned means comprises an undercut profile on the underside of said seat supporting frame.
10. A chair according to claim 1, in which said seat comprises a hollow body of plastics material.
11. A chair according to claim 10 in which said seat, in its outer edge region, has a moulded recess which is shaped to partially accommodate said seat support frame.
12. A chair according to claim 10 in which said hollow body of plastics material has a lower wall forming the underside of the seat, said lower wall having a strengthening profile.
13. A chair according to claim 10, in which said hollow body of plastics material has a lower wall forming the underside of the seat, said lower wall having moulded therein receiving means for supporting pads and in which protective supporting pads are received in said receiving means.
14. A chair according to claim 1, in which said back rest is inserted between the upper ends of said supports and has a thickness no greater than the dimensions of said supports in the longitudinal direction of the chair.
15. A chair according to claim 1, in which said back rest comprises a hollow body of plastics material.
16. A chair according to claim 15, in which said hollow body of plastics material has a rear wall forming the rear of the back rest, said rear wall having therein a handle-like recess which does not pierce said rear wall.
17. A chair according to claim 15 in which said hollow body forming said back rest comprises a substantially closed blow-moulded body.
18. A chair according to claim 10 in which said hollow body forming said seat comprises a substantially closed blow-moulded body.
19. A chair according to claim 1 in which said seat supporting frame is so shaped that said seat can be pushed therein position from the rear.
20. A chair according to claim 10 in which said seat supporting frame is so shaped that said seat can be pushed into seat supporting frame from the rear.
21. A chair according to claim 20 further comprising projection means in the region between the seat and the seat supporting frame for latching said seat in said seat supporting frame.
22. A chair according to claim 21 in which said projection means is formed integrally on said seat and said seat supporting frame has aperture means therein receiving said projecting means.
23. A chair according to claim 1 in which said seat lies on top of said seat supporting frame and in which fastening means extends through said seat to said seat supporting frame to secure the former to the latter.
UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 9 2 7 DATED I 8-.-l275 iN\/"ENTOR(S) Falk Mueller it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
First page item  reference to the German application should be deleted. I
Col. 2, line 4.4, "feed should read -feel Col. 4 line 38, (of. should read (cf and "On" should read One Col. 4, line 51, "not" should read no- Col. 4, line 55, "screwedon should read screwed Col. 6, line 63, "projecting" should read --projection Signed and Sealed this third Day of February 1976 [SEAL] Attest:
RUTH c. MASON C. MARSHALL DANN Arresting Officer Commissioner uj'Patents and Trademarks