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Publication numberUS3369840 A
Publication typeGrant
Publication dateFeb 20, 1968
Filing dateJul 22, 1966
Priority dateJul 23, 1965
Also published asCA806983A, DE1297306B
Publication numberUS 3369840 A, US 3369840A, US-A-3369840, US3369840 A, US3369840A
InventorsDufton Ronald
Original AssigneeDare Inglis Products Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Chair tilting mechanism
US 3369840 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

1 Feb. 20, 1968 R. DUFTON v 3,369,840

CHAIR TILTING MECHANISM Filed July 22, 1966 2 Sheets-Sheet 1 y 764 55 40 M a /5@ I nvenlor Ronald Dufton MISEGADES 8c DOUGLAS Attorney United States Patent 3,369,840 CHAIR TILTING MECHANISM Ronald Dufton, Bushey Heath, England, assignor to Dare-Inglis Products Limited, Harrow, Middlesex, England, a British company Filed July 22, 1966, Ser. No. 567,209 Claims priority, application Great Britain, July 23, 1965, 31,603/ 65 7 Claims. (Cl. 297-303) ABSTRACT OF THE DISCLOSURE A chair tilting mechanism comprising a base portion, a seat portion, a back-rest portion pivotally connected to the base portion, an elongated leaf spring mounted transversely of the pivot axis between the base and back-rest portions to resist pivotal movement therebetween; a tension adjustment device connecting the forward end of the leaf spring to the base portion, the rearward end of the leaf spring engaging the back-rest portion; an abutment pivotally mounted on the base portion engaging the leaf spring substantially at the center thereof to effect bowing of the leaf spring.

This invention concerns a chair tilting mechanism.

The principal object of the invention is the provision of an improved chair tilting mechanism which is robust and occupies less vertical space and may thus be housed conveniently beneath the seat portion of the chair.

Such chair tilting mechanisms have theretofore comprised structures employing a leaf spring having a free end and about whose other end the spring bends to provide the necessary resilience for the structure.

The improved chair tilting mechanism of the present invention differs in structure and action from such leaf spring structures as have heretofore been known in that the resiliency of the mechanism is produced by bowing the leaf spring at its center. Thus either end of the spring is completely free and so there is less tendency for the spring to fracture and the mechanism occupies less vertical space.

According to the present invention there is provided a chair tilting mechanism comprising a base portion, a seat portion, a back-rest portion, means connected to the backrest portion, means pivotally connecting the back-rest portion to the base portion, an elongated leaf spring mounted transversely of the pivot axis between the base and backrest portions and adapted to resist pivotal movement therebetween, a tension adjustment device for varying the residual tension in the spring, the forward end of the leaf spring being connected to the base portion by way of the tension adjustment device, the rearward end of the leaf spring engaging the means connected to the back-rest portion, and an abutment pivotally mounted on the base portion which engage the leaf spring substantially at the center thereof to effect bowing of the leaf spring.

The seat portion and back-rest portion may be pivotally connected as a unit to the base portion.

Alternatively the seat and back-rest portions may be pivotally connected to the base portion in such a way as to permit the back-rest portion to be pivoted with respect to the base portion to a greater extent than the seat portion. Thus the locus of movement of the back-rest portion may have a smaller radius than that of the locus of movement of the seat portion.

The base portion may comprise a cradle which is rotatably mounted on a pillar. The back-rest portion is preferably pivotally connected to the cradle about an axis disposed to the rear of the pillar.

The seat portion may be pivotally connected to the "ice cradle forwardly of the pillar and is connected by linkage means to the back-rest portion.

The invention is illustrated; namely by way of example, in the accompanying drawings, in which:

FIGURE 1 is a part-sectional elevation of a chair according to the present invention,

FIGURE 2 is a part-sectional elevation of part of the chair shown in FIGURE 1,

FIGURE 3 is a part-sectional elevation of a modified form of chair according to the present invention,

FIGURE 4 is a view similar to FIGURE 3 with the components in a different relative position, and

FIGURE 5 is a part cut-away perspective view of part of the chair shown in FIGURES 3 and 4.

In FIGURE 1 there is shown an ofiice chair comprising a seat portion 11 and a back-seat portion 12 attached to the seat portion 11. The seat portion 11 is provided, on its underside and somewhat to the rear of the centre thereof, with brackets 13. The brackets 13 are pivoted by a common pivot 14 to a cradle 15 which is rotatably mounted on the central stem 16 of a pillar type base for the chair, the cradle 15 and stem 16 forming the base portion of a tilting mechanism permitting tilting of the back-rest 12. As will be seen, the pivot 14 is disposed somewhat to the rear of the stem 16. Attached to an extension arm 17 of the cradle is a tension adjustment device 18, shown in more detail in FIGURE 2, which cooperates with the forward end 19 of a laminated leaf spring 20. The leaf spring 20 is elongate, the forward end 19 of the leaf spring 20 being adjacent a pivot pin 21 at the extreme forward end of cradle 15, while the rearward end 22 of the leaf spring 20 engages a pivot pin 23 adjacent the rear of the seat portion 11. The leaf spring 20 is thus mounted transversely of the pivot 14 which forms the pivot axis between the back-rest portion 12 and the cradle 15. The pivot pin 23 is attached to bosses 24 on the underside of the seat portion 11 adjacent its rear end.

An abutment 25, which is pivoted to the cradle 15 on a pivot 26, bears against the underside of the leaf spring 20 adjacent its centre between the ends 19, 22 to elfect bowing of the leaf spring 20.

It will be appreciated that, when not in use, the leaf spring 20 will be almost linear with the seat portion 11 positioned substantially horizontally. In use, however, the

seat portion 11 and back-rest portion 12 will tilt rearwardly about the pivot 14 to the position shown, for example, in FIGURE 1, and will effect flexing of the leaf spring 20 by engagement between the pivot 23 and the rearward end 22 of the leaf spring 20. The leaf spring 20 will bow in the manner shown, since it is effectively fixed with respect to the cradle 15, due to tension adjustment device 18 or, if device 18 is slack, due to pivot pin 21, and the abutment 25 will resist movement of the leaf spring 20, but will permit bowing thereof, such that the tensioning of the leaf spring 20 will resist the tilting action of the chair. It will be appreciated that the back-rest portion 12 will tilt with the seat portion 11 and to the same extent.

Referring now to FIGURE 2., the tension adjustment device 18 is shown in more detail. It will be seen that the forward end 19 of the leaf spring 20 is provided with a central aperture 27 within which there is disposed a screwthreaded bolt 28, the head 29 of which is too large to pass through the aperture 27 and thus rests on the upper surface of the leaf spring 20. The screw threaded bolt 28 passes through an aperture 30 in the arm 17 and is provided on the underside of the arm 17 with a nut 31 having an axial projection 32 which engages the undersurface of the arm 17, so that rotation of the nut 31 adjusts the position of the head 29 of the bolt 28. Thus by rotating the nut 31, the head 29 of the bolt 28 can be moved vertically so as to draw the end 19 of the leaf spring 20 into the broken-line position indicated at 19' to thereby pre-tension the leaf spring 20 so that it provides greater resistance to tilting action of the chair. Thus the tension in the leaf spring 20 can be adjusted to suit the weight of the person using the chair. When the tension adjustment device 18 is very slack, the pivot pin 21 provides the restraining force on the upper side of the end 19 of the leaf spring 20 during tilting of the chair. At other times, the head 29 provides the restraining force.

Referring now to the embodiment shown in FIGURES 3 to 5, there is shown a somewhat modified and preferred form of chair which provides a tilting action similar to that provided by the arrangement of FIGURE 1, but also provides for relative movement between the back-rest and seat portions. In view of the similarity between the construction of FIGURES 3 to and that of FIGURES 1 and 2, similar components have been allocated similar reference numerals with the addition of the reference letter a.

Referring to FIGURES 3 to 5, it will be seen that seat portion 11a is pivoted to cradle a at 21a and not at 14a, and thus is pivoted thereto forwardly of the stem 16. Back-rest 12a is connected at 34- to two integral arms 35, 36 which are disposed on opposite sides of cradle 15a and are pivoted thereto by the pivot 14a. Arms 35, 36 are pivoted intermediate the ends thereof to links 40, 41 respectively which in turn are pivoted to the seat portion 11a at opposite ends of the pivot 23a. Thus the rearward end of the leaf spring a controls the position of the back-rest portion 12a by engaging the pivot 23a which is connected to the back-rest portion 12a by the links 40, 41 and the arms 35, 36.

It will be appreciated that the back-rest portion 12a is adapted to pivot about pivot 14a and, as clearly indicated in FIGURE 3, the are x which defines the locus of movement of the back-rest portion 12a has a smaller radius than the arc y which defines the locus of the movement of the seat portion 11a. Thus, upon pivotal movement of seat portion 11a from the position indicated in FIGURE 3, to the position indicated in FIGURE 4, a pivotal movement of the seat portion 11a through an angle a will result in pivotal movement of the back-rest 12a through an angle a-i-B, where ,8 is the angle between the seat portion 11a and the arms 35, 36.

The use of an elongate resilient leaf spring 20 in the tilting mechanism allows the latter to be made very compact so as to save height.

Although shown as a multi-leaf spring, the leaf spring 20 can, of course, be a single leaf. It will be appreciated that, in the embodiments of both FIGURES l and 2 and FIGURES 3 to 5, the forward end 19 of the leaf spring will be acted upon by the pivot pin 21 (or 21a) when the tension adjustment device 18, 18a is slackened off, but, whether the pivot pin 21, 21a or tension adjustment device 18, 18a acts on the end 19 of the spring, the end 19 of the spring can still be considered as being fixed relative to the cradle 15 of the base portion of the seat.

In the particular embodiments described above, the seat portion 11, or 11a and the back-rest portion 12 or 12a are upholstered. It will, however, be appreciated that the terms seat portion and back-rest portion can refer, and are intended to include within their scope, the frames only for the seat and back-rest, i.e. as shown in FIGURE 4. The frame for the seat portion, moreover, may be removable without such removal affecting the operating of the tilting mechanism.

I claim:

1. A chair tilting mechanism comprising a base portion, a seat portion, a back-rest portion, means connected to the back-rest portion, means pivotally connecting the back-rest portion to the base portion, an elongated leaf spring mounted transversely of the pivot axis between the base and back-rest portions and adapted to resist pivotal movement therebetween, a tension adjustment device for varying the residual tension in the spring, the forward end of the leaf spring being connected to the base portion by way of the tension adjustment device, the rearward end of the leaf spring engaging the means connected to the back-rest portion, and an abutment pivotally mounted on the base portion which engages the leaf spring substantially at the center thereof to effect bowing of the leaf spring.

2. A mechanism as claimed in claim 1 in which the seat portion and back-rest portion are pivotally connected as a unit to the base portion.

3. A mechanism as claimed in claim 1 in which the seat and back-rest portions are both pivotally connected to the base portion to permit the back-rest to be pivoted with respect to the base portion to a greater extent than the seat portion.

4. A mechanism as claimed in claim 3 in which the locus of movement of the back-rest portion has a smaller radius than that of the locus of movement of the seat portion.

5. A mechanism as claimed in claim 3 in which the base portion comprises a cradle which is rotatably mounted on a pillar.

6. A mechanism as claimed in claim 5 in which the back-rest portion is pivotally connected to the cradle about an axis disposed to the rear of the pillar.

'7. A mechanism as claimed in claim 5 in which the seat portion is pivotally connected to the cradle forwardly of the pillar and is connected by linkage means to the back-rest portion.

References Cited UNITED STATES PATENTS 2,313,559 3/1943 Larsen et al 297302 2,528,223 10/1950 Fox 297301 2,818,911 l/1958 Syak 297303 X 2,956,619 10/1960 Scherer 297303 3,290,091 12/1966 Goodman 297302 BOBBY R. GAY, Primary Examiner.

DAVID J. WILLIAMOWSKY, Examiner.

G. O. FINCH, Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2313559 *Jun 28, 1940Mar 9, 1943Heywood Wakefield CoChair
US2528223 *Nov 29, 1946Oct 31, 1950Seng CoChair iron
US2818911 *Nov 5, 1954Jan 7, 1958Trumbull Dev CorpTiltable office chair
US2956619 *Oct 3, 1958Oct 18, 1960Cramer Posture Chair Company ITilt back chair
US3290091 *Jan 14, 1966Dec 6, 1966Goodman RobertChairs with tiltable portions
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3603641 *Sep 12, 1969Sep 7, 1971La Z Boy Chair CoOffice-type chair
US4077596 *Jun 18, 1975Mar 7, 1978Bliss & Laughlin Industries, IncorporatedLow silhouette chair tilting control assembly
US4773706 *Jul 6, 1987Sep 27, 1988Dr. Ing. H.C.F. Porsche AktiengesellschaftChair, particularly an office chair
US5267777 *Jan 15, 1992Dec 7, 1993Lavaco Industries, Inc.Resilient chair support
US5725277 *Jul 18, 1996Mar 10, 1998Steelcase Inc.Synchrotilt chair
US6250715Jan 20, 1999Jun 26, 2001Herman Miller, Inc.Chair
US6367876Apr 11, 2001Apr 9, 2002Herman Miller, Inc.Chair
US6688688 *Jan 16, 2002Feb 10, 2004Peter RoederChair
US6692075 *Sep 25, 2001Feb 17, 2004Armin SanderChair having a synchronously adjustable seat and backrest
US6817668May 16, 2003Nov 16, 2004Steelcase Development CorporationSeating unit with variable back stop and seat bias
US6880886Jun 5, 2003Apr 19, 2005Steelcase Development CorporationCombined tension and back stop function for seating unit
US6991291Feb 1, 2005Jan 31, 2006Steelcase Development CorporationBack construction for seating unit having spring bias
US7004543Aug 24, 2004Feb 28, 2006Herman Miller, Inc.Chair
US7040709Feb 1, 2005May 9, 2006Steelcase Development CorporationBack construction for seating unit having inverted U-shaped frame
US7114777Sep 21, 2004Oct 3, 2006Steelcase Development CorporationChair having reclineable back and movable seat
US7131700Feb 1, 2005Nov 7, 2006Steelcase Development CorporationBack construction for seating unit
US7165811Jun 5, 2003Jan 23, 2007Steelcase Development CorporationControl mechanism for seating unit
US7237841Feb 1, 2005Jul 3, 2007Steelcase Development CorporationBack construction with flexible lumbar
US7427105Sep 18, 2006Sep 23, 2008Steelcase Inc.Back construction for seating unit
US7458637Jun 10, 2004Dec 2, 2008Steelcase Inc.Back construction with flexible lumbar
US7540465Oct 4, 2005Jun 2, 2009Miller Charles AShock absorbing motor mount for vibratory belt drive
US7806478 *Jan 4, 2007Oct 5, 2010Sava CvekTask chair with dual tilting capabilities
US7922248Apr 12, 2011Herman Miller, Inc.Seating structure and methods for the use thereof
US8210611Apr 11, 2011Jul 3, 2012Herman Miller, Inc.Seating structure and methods for the use thereof
US8262162 *Sep 11, 2012Herman Miller, Inc.Biasing mechanism for a seating structure and methods for the use thereof
US8419133Apr 16, 2013Herman Miller, Inc.Seating structure with independently adjustable back
US8714645Jan 28, 2011May 6, 2014Sava CvekPivoting mechanism with gross and fine resistance adjustment
US20030193227 *May 16, 2003Oct 16, 2003Dekraker LarrySeating unit with variable back stop and seat bias
US20040245839 *Jun 5, 2003Dec 9, 2004Bodnar David A.Combined tension and back stop function for seating unit
US20050017557 *Aug 24, 2004Jan 27, 2005Herman Miller, Inc.Chair
US20050046254 *Sep 21, 2004Mar 3, 2005Knoblock Glenn A.Chair having reclineable back and movable seat
US20050127729 *Feb 1, 2005Jun 16, 2005Knoblock Glenn A.Back construction for seating unit having spring bias
US20050179292 *Feb 1, 2005Aug 18, 2005Knoblock Glenn A.Back construction for seating unit having inverted U-shaped frame
US20050231013 *Feb 1, 2005Oct 20, 2005Knoblock Glenn ABack construction for seating unit
US20050275263 *Jun 10, 2004Dec 15, 2005Norman Christopher JBack construction with flexible lumbar
US20050275264 *Feb 1, 2005Dec 15, 2005Norman Christopher JBack construction with flexible lumbar
US20070024098 *Sep 18, 2006Feb 1, 2007Knoblock Glenn ABack construction for seating unit
US20090044820 *Jan 29, 2008Feb 19, 2009Anastasia SoareStencils and gauging device for aesthetically pleasing eyebrow shaping
US20110241399 *Oct 6, 2011Castro Jr Elindo GBiasing mechanism for a seating structure and methods for the use thereof
DE3101692A1 *Jan 21, 1981Aug 19, 1982Dauphin F W Buerositzmoebel"sitzmoebel, insbesondere drehbarer buerostuhl"
DE3638273A1 *Nov 10, 1986Apr 21, 1988Thonet Geb GmbhPiece of seating furniture
EP0242140A2 *Apr 10, 1987Oct 21, 1987Steelcase Inc.Integrated chair and control
EP1342432A2 *Feb 24, 2003Sep 10, 2003Eckhard Dipl.-Ing. HansenChair
EP1419718A1 *Sep 25, 2003May 19, 2004Hodry Metallwarenfabrik R.Hoppe Ges.m.b.H & Co. KGMounting for television chair
EP1449462A1 *Jan 22, 2004Aug 25, 2004Eckhard Dipl.-Ing. HansenChair
WO1993013695A1 *Jan 13, 1993Jul 22, 1993Lavaco Industries, Inc.Resilient chair support
WO1993019644A1 *Mar 18, 1993Oct 14, 1993Martin Stoll GmbhChair
WO2014166804A1 *Apr 3, 2014Oct 16, 2014Johann Burkhard SchmitzMechanical subassembly for a chair and chair having such a mechanical subassembly
WO2014166808A1 *Apr 3, 2014Oct 16, 2014Johann Burkhard SchmitzMechanical subassembly for a chair and chair having such a mechanical subassembly
Classifications
U.S. Classification297/300.1, 297/303.1
International ClassificationA47C1/032, A47C7/44
Cooperative ClassificationA47C1/03277, A47C1/03255, A47C1/03266
European ClassificationA47C1/032C2, A47C1/032C6, A47C1/032B