Resilient Hinging Device For Chairs And The Like

Abstract

In a resilient hinge for chairs and the like, having an upper hinge part to be attached to the seat or back of the chair and pivoted on a bottom hinge part to be fixed to the bottom frame, with a biased spring member acting therebetween for resiliently opposing backward tilting, the spring member is capable of being displaced radially to the pivotal axis for adjusting the biasing torque, the spring member engaging an entraining slide guided in the fixed hinge part. Movement of the entraining slide is caused by operating a handle on a lever pivoted on an upwardly projecting cone on the fixed hinge part and having teeth engaging a rack guided in the fixed hinge part for motion parallel to the hinge axis and carrying studs engaging oblique slots in the entraining member so as to afford a force-increasing transmission of motion from the lever to the spring member. The handle extends substantially to the edge of the seat so as to be easily accessible. The cone is hollow for matching a column in the bottom frame of the chair. The spring member is composed of leaf springs bent into U-shape opening towards the rear and placed one outside the other. They are in mutual contact at the bend and at the ends of the respective inner springs, with the lengths of the springs increasing from the innermost to the outermost. The lower legs of the leaf springs are bifurcated with diverging inner edges and straddle the cone, and the upper legs have a substantially complementary taper.

Description

BACKGROUND OF THE INVENTION

The invention relates to resilient hinging devices for chairs and the like comprising a member adapted to be attached to the seat or back of a chair and mounted for pivotal movement about a horizontal axis of a member adapted to be attached to the bottom frame of the chair, against the action of a spring member acting between these hinge members substantially tangentially to the pivotal axis and biased in a position of the movable hinge member defined by abutments, and in which position the spring member can be displaced by an actuating member in a direction substantially radial to the pivotal axis and transversely of its acting direction, for adjusting the biasing torque. A pivotal hinge of this kind is previously known, for example from the applicant's U. S. Pat. No. 3,284,133 dated Nov. 8, 1966 and has the considerable advantage that an adjustment of the baising torque and hence of the relation between the spring torque and pivotal angle can take place without substantially varying the spring tension or overcoming spring force.

SUMMARY OF THE INVENTION

The present invention has for an object to improve pivotal hinges of the kind referred to, primarily by making it possible to effect the adjustment easily while sitting in the chair. In prior structure described in the said patent this is hardly possible since the adjustment is effected with a screw spindle which is placed in a position difficult to access on the bottom side of the chair and which in the case of a considerable biasing force, which is desirable for affording a sufficient torque in a device of small dimensions, must be turned with a considerable force in order to overcome the friction on the loaded spring member.

An improvement afforded by the present invention in this connection consists in that the actuating member instead comprises a lever which is mounted on one of the hinge members for pivotal motion in a substantially horizontal plane and is connected by a force-increasing mechanism to an entraining member mechanically connected to the spring member and mounted for displacement in the direction of adjustment. The lever may be provided with a handle extending substantially to the edge of the seat of the chair so that the manipulation can take place easily with a long moment arm and the mechanism will nevertheless largely remain concealed, as the lever with the handle may extend closely under the seat and the shape of the handle can be adapted to the shape and dimensions of the seat without changing the remaining mechanism.

The invention also teaches further features which make the manner of operation consistent with a compact design and easy mounting, and further provides a spring member which is adapted to be used in this connection and at the same time is designed for affording the desired resilient action while using a minimum of material and for being made from commercially available spring steel stock.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention will be described more in detail in connection with a preferred embodiment illustrated in the accompanying drawings.

In the drawings the FIGS. 1 to 4 are in half the scale of the remaining FIGS. 5 to 7.

FIG. 1 is an exploded side view of the mechanism partly in section in the central vertical plane.

FIG. 2 is a bottom view of the actuating lever with handle.

FIG. 3 is a top view of the spring member partly in section in the central horizontal plane indicated at III--III in FIG. 6.

FIG. 4 is a bottom view of a sliding rack.

FIG. 5 shows the pivotal hinge as viewed from the front and in section through the pivotal axis as indicated by the line V--V in FIG. 6.

FIG. 6 is a side view of the same in longitudinal section substantially along the line VI--VI in FIG. 7, yet without the spring member being shown in section.

FIG. 7 is a top view of the bottom part of the hinge with the adjusting mechanism inserted.

The device comprises a metallic bottom part or fixed hinge member 1 largely of the shape of a box open at the top and at the rear. From a downwardly offset portion 2 of the box bottom there projects upwards an upwardly tapering open hollow cone 3 adapted to be mounted on a column 4 or the like in the bottom frame of the chair (diagrammatically indicated in FIG. 6). In the side walls 5, 5 there are mounted bearing sleeves 6, 6 for pivotally supporting a transverse hollow shaft 7 which at its extremities outside the bottom part is fixed in downwardly projecting side walls 8 of an upper part or movable hinge member 9 formed with a largely rectangular top plate 10, which for example by means of screws in the corners can be attached to the part 11 to be supported, such as a chair seat, a supporting frame for a chair back or the like.

Slidably supported on the bottom of the fixed member 1 is an entraining slide 12 guided between the walls 5, the slide 12 extending throughout the width of the bottom in front of the cone 3 and being formed with two branches extending on either side of the cone and terminating in upward projections 13, 13 formed by bending the end portions upwards and inwards, whereas the branches at 12 rest on the upper face of the bottom, whereas the branches at the rear rest on ribs 14 projecting from the portion 2 and extending obliquely to either side.

The slide 12 serves as an entraining member for a spring member 15 of the pivotal hinge. As appears from the FIGS. 1, 3, 5 and 6, this member is composed of a plurality, four in the example shown, of leaf springs extending outside each other and bent into U-shape opening towards the rear and having one leg above and one below the shaft 7. In order to make the stress on the spring material as even as possible at all points, the dimensions of the various springs are adapted to the load partly by staggering the length of the leaf springs so that it decreases from the outermost to the innermost and partly by making the effective width of each spring decrease towards the free extremities both in the upper leg and in the lower leg. The radii of curvature in the bend are staggered so that each spring when engaging the bend of the adjacent spring surrounding it exerts an outward pressure on the same at the extremities of its legs. The upward branches taper towards the end and the outermost slidably engages a plane bottom or sliding face 16 on the upper part 9. The lower legs are cut out deeply and symmetrically from the end and project on either side of the cone 3, the outermost leg having U-shaped end portions engaging the projections 13 of the slide 12. The free edges of the upper and lower legs may conveniently have substantially complementary shapes, so that the leaf springs can be stamped practically without loss.

In the slide 12 there are formed two oblique parallel slots 17, 17 into which project studs 18 of correspondingly oblique parallelogram shape from a sliding rack 19 supported in the bottom of the member 1 for displacement parallel to the shaft 7 just in front of the cone 3. On its bottom side the rack 19 is formed with teeth 20 engaging a corresponding toothed wheel segment 21 on a lever 22 pivotally mounted with a circular opening 23 on the root of the cone 3 and substantially concentric to the latter. The lever 22 rests on the bottom of the lowered portion 2 at a distance below the slide 12 and is capable of pivotal movement in the horizontal plane by a suitable angle limited by the ribs 14 forming stops for the lever. The lever 22 projects behind the bottom part 1 and extends further at an obtuse angle towards the right hand side of the hinge. To the free extremity of the lever there is attached a handle 24 of suitable design and length for easy operation by the person sitting in the chair. For arresting the lever in the desired angular position, the lowered bottom portion 2 is, near its rear edge, formed with teeth 25 in its upper face, which are engaged by a tooth 26 (FIG. 2) on the bottom side of the lever 22, which is kept depressed by a leaf spring 26' (partly broken away in FIG. 7) supported in grooves 26 in the ribs 14 and locked against upward movement by engaging the lower ends of ribs 28 on the inner faces of the side walls 5.

Another possibility of arresting the lever 22 in desired angular positions might be to make the slope of the slots 17 in the entraining slide 12 so small that the sliding connection with the studs 18 will be self-arresting.

In the starting position shown, the spring member 15 is biased, the lower legs thereof exerting downward pressure on the projections 13 of the slide 12 and hence via the latter on the ribs 14 in the bottom of the fixed member 1, whereas the upper legs act on the sliding face 16 of the movable member 9 and hence exert a torque on the same in the clockwise direction whereby the top plate of the movable member is pressed against abutments 30, 30 at the upper edges of the forward portions of the side walls 5 of the fixed member at the front. When the seated person then leans backwards, it will be possible for the movable hinge member while increasing the load on the spring member 15 to turn counter-clockwise as viewed in FIG. 6 until its top plate engages abutments 31, 31 on the side walls 5 at the rear. If the person then desires to change the biasing torque, it will be possible in the starting position of the mechanism shown, in which position the sliding face 16 extends largely parallel to the guiding direction for the entraining slide 12, to turn the lever 22 in one direction or the other, whereby the lever via the segment 21 and the teeth 20 will displace the rack 19, which will then by the stud and slot connections 17, 18 cause a displacement of the slide 12 and hence of the spring member 15 forwards or backwards. Hence, the line of action of the resulting spring force will be displaced towards the pivotal axis defined by the shaft 7 so that the spring member will act with an increased or reduced moment arm and its torque will vary correspondingly.

The mounting is extremely simple. At first the lever 22, the retaining spring 26', the sliding rack 19, the entraining slide 12 and the spring member 15 are simply placed in position in the bottom part 1, in which the sleeves 6 have been mounted, and in a suitable jig the whole is compressed together with the upper part 9 until the axial bores of the latter become aligned with the bearing sleeves, whereafter the shaft 7 is forced into position and riveted.

Claims

What I claim is

1. Resilient hinging device for chairs and the like, comprising a first hinge member for attachment to a seat or back of the chair, a second hinge member for attachment to a bottom frame of the chair, abutments on said second hinge member, said first hinge member being supported for pivotal movement about a horizontal axis on said second hinge member, a spring member acting between said first and second hinge members substantially tangentially to the pivotal axis and biased in a starting position of the first hinge member defined by the abutments, in which position the spring member can be displaced by an actuating member in a direction substantially radial to the pivotal axis and transversely of its acting direction for adjusting the biasing torque, characterized in that the actuating member comprises a lever supported on one of said hinge members for pivotal motion in a substantially horizontal plane, a force increasing mechanism, an entraining member mechanically connected to the spring member and supported for displacement in the direction of adjustment and said lever being connected via the force increasing mechanism to the entraining member.

2. Resilient hinging device as claimed in claim 1, characterized in that the lever is, at its inner extremity, in entraining engagement with a slide guided in the direction of the hinge axis and engaging the entraining member for the spring member by a double stud and slot connection.

3. Resilient hinging device as claimed in claim 2, characterized in that the stud and slot connections are self-arresting.

4. Resilient hinging device as claimed in claim 2, characterized in that the lever is formed with a toothed wheel segment and the transversely movable slide with corresponding rack teeth.

5. Resilient hinging device as claimed in claim 1, characterized in that the entraining member is guided in the second hinge member and transmits pressure between the latter and the spring member.

6. Resilient hinging device as claimed in claim 1, in which the second hinge member is provided with a hollow cone for mounting on a column in the bottom frame of the chair, characterized in that the hollow cone projects upwards towards the first hinge member.

7. Resilient hinging device as claimed in claim 6, characterized in that the lever is mounted in the second hinge member on the outside of the hollow cone and with its pivotal axis substantially in the axis of the cone.

8. Resilient hinging device as claimed in claim 7, characterized in that the portion of the spring member acting on the second hinge member is distributed substantially symmetrically on both sides of the cone.

9. Resilient hinging device as claimed in claim 1, characterized in that the spring member is composed of a plurality of leaf springs curved in the plane normal to the hinge axis and placed in mutual engagement one outside the other, the outermost leaf spring engaging the hinge members at its ends.

10. Resilient hinging device as claimed in claim 9, characterized in that the leaf springs have decreasing length and radii of curvature counted from the outermost to the innermost, the individual springs engaging the respective adjacent springs on the outside at their ends and at the bottom of the bends.

11. Resilient hinging device as claimed in claim 9, characterized in that the springs are bent slightly more than 180.degree. and loosely inserted one into the other.

12. Resilient hinging device as claimed in claim 9, characterized in that the effective width of each spring decreases towards both ends thereof.

13. Resilient hinging device as claimed in claim 12, characterized in that the end portions of each spring have mutually complementary shapes.

14. Resilient hinging device as claimed in claim 6, characterized in that the spring member is composed of a plurality of leaf springs curved in the plane normal to the pivotal axis and placed in mutual engagement one outside the other, the outermost leaf spring engaging the hinge members at its ends, that the end portions of the springs at the end engaging the second hinge member are bifurcated with diverging inner edges and straddle said cone, and that their end portions at the opposite end have a substantially complementary taper.