Piece of rotary seating furniture

Abstract

A piece of seating furniture having a base and a seat unit, wherein the base and the seat unit have provided between them a pivot bearing including a base-side bearing device and a seat-unit-side bearing device, via which the seat unit is rotatable about a vertical axis in relation to the base, and the pivot bearing has a switchable blocking device, via which the rotary movement capability of the bearing devices in relation to one another can be blocked.

Claims

1. A piece of seating furniture having a base; a seat unit; and a pivot bearing provided between the base and the seat unit, the pivot bearing comprising a base-side bearing device and a seat-unit-side bearing device, by which the seat unit can be rotated about a vertical axis in relation to the base; the pivot bearing having a switchable blocking device, by which a rotary movement capability of the bearing devices in relation to one another can be blocked; and the blocking device comprising an encircling blocking surface on a first one of the bearing devices, at least one torsion spring which wraps around the encircling blocking surface and being fastened on a second one of the bearing devices and having an internal diameter which is variable in dependence on a stressing state of the at least one torsion spring, and a switching device by which the at least one torsion spring can be subjected to stressing and relieved of stressing; wherein the at least one torsion spring, in a relieved-of-stressing state, butts against the blocking surface and thus prevents relative rotary movement between the bearing devices.

2. The piece of seating furniture according to claim 1, wherein the at least one torsion spring has two torque-inducing portions, of which a circumferentially directed relative movement can subject the at least one torsion spring to stressing and relieve the at least one torsion spring of stressing.

3. The piece of seating furniture according to claim 2, wherein one of the two torque-inducing portions is fastened on the second one of the bearing devices such that the second one of the bearing devices cannot be moved in a circumferential direction.

4. The piece of seating furniture according to claim 1, wherein the at least one torsion spring wraps around the blocking surface over an angle of at least approximately 360.

5. The piece of seating furniture according to claim 1, wherein the switching device has a switching carriage, which can be moved axially with guidance along the first one or the second one of the bearing devices and which is operatively coupled to the at least one torsion spring such that an axial displacement of the switching carriage gives rise to the at least one torsion spring being subjected to stressing and thus to the blocking devices to being released.

6. The piece of seating furniture according to claim 5, further including a restoring spring, by which the switching carriage is forced permanently in a direction of an end position.

7. The piece of seating furniture according to claim 1, wherein the switching device has a switching lever, which is fitted in a pivotable manner in relation to the first one or the second one of the bearing devices and which is operatively coupled to the at least one torsion spring such that a pivoting movement of the switching lever gives rise to the at least one torsion spring being subjected to stressing and thus to the blocking device being released.

8. The piece of seating furniture according to claim 1, wherein the piece of seating furniture has a standing-up-aiding function, by which a seat surface can be raised, and wherein the blocking device is operatively coupled to the standing-up-aiding function such that the blocking device assumes a blocked state when the standing-up-aiding function is actuated.

9. The piece of seating furniture according to claim 1, wherein the piece of seating furniture has an operating lever for manual actuation, which can be used to switch the blocking device.

10. The piece of seating furniture according to claim 1, wherein the base-side bearing device is formed by the first one of the bearing devices with the encircling blocking surface, and the seat-unit-side bearing device is formed by the second one of the bearing devices with the at least one torsion spring.

11. A fitting for a piece of seating furniture comprising: a base portion for fitting on a base of the piece of seating furniture; a seat portion, on which to fit a seat unit of the piece of seating furniture; and a pivot bearing provided between the base portion and the seat portion, the pivot bearing comprising a base-side bearing device and a seat-unit-side bearing device, by which the seat portion can be rotated about a vertical axis in relation to the base portion; the pivot bearing having a switchable blocking device, by which a rotary movement capability of the bearing devices in relation to one another can be blocked; the blocking device comprising an encircling blocking surface on a first one of the bearing devices, at least one torsion spring which wraps around the blocking surface and is fastened on a second one of the bearing devices and has an internal diameter which is variable in dependence on a stressing state of the at least one torsion spring, and a switching device, by which the at least one torsion spring can be subjected to stressing and relieved of stressing; wherein the at least one torsion spring, in a relieved-of-stressing state, butts against the blocking surface and thus prevents relative rotary movement between the bearing devices.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further aspects and advantages of the invention can be gathered from the claims and from the following description of a preferred exemplary embodiment of the invention, which will be explained with reference to the figures, in which:

(2) FIGS. 1A-1C show a piece of seating furniture according to the invention in a perspective view, in a view from the rear and in a view from the front,

(3) FIG. 2 shows the pivot bearing of the piece of seating furniture according to FIG. 1 together with a blocking device,

(4) FIGS. 3a to 3c show the blocking device in the freed state,

(5) FIGS. 4a to 4c show the blocking device in the blocked state,

(6) FIGS. 5A and 5B show the piece of seating furniture from FIGS. 1a to 1c with the standing-up aid activated, and

(7) FIGS. 6A to 6B show an alternative form of blocking device.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

(8) FIGS. 1a to 1c show a piece of seating furniture according to the invention in the manner of a chair. This piece of seating furniture has a seat unit 10, in this case comprising, in addition to a seat surface 12, which is illustrated in the non-upholstered state, also a backrest 14 and a legrest 16. The seat unit 10 can be rotated as a whole about a vertical axis 2 in relation to a base 20. The base 20 is provided for positioning the piece of seating furniture at a fixed location, but could also be provided, in the manner of office chairs, with rollers, in order to allow the chair to be displaced straightforwardly as a whole.

(9) The rotatability of the seat unit is achieved via a pivot bearing 30, which is arranged directly above the base 20.

(10) Said pivot bearing can be seen in section in FIG. 2. It comprises in particular an inner axial portion 32, which is rotationally fixed in relation to the seat unit 12, and a bearing sleeve 34, which accommodates the axial portion 32 and is a fixed constituent part of the base 20.

(11) The rotatability which said pivot bearing having the components 32, 34 provides for the seat unit 10 in relation to the base 20 can be blocked, in the case of a piece of seating furniture according to the invention, such that rotation can be prevented, or at least made considerably more difficult, in certain cases.

(12) The main components of the blocking device provided for this purpose, with reference to FIGS. 2, 3 and 4, are primarily a blocking surface 40, which is formed by the outer surface of the bearing sleeve 34, and two torsion springs 50a, 50b, each designed in the manner of leg springs. The two leg springs 50a, 50b each have one leg 51a, 51b fitted on the seat unit 12 at a fixed location as seen in relation to a circumferential direction about the axis of rotation 2, whereas the respectively opposite legs 52a, 52b can be moved in principle in relation to the circumferential direction. A circumferentially directed movement of the legs 52a, 52b results in the torsion springs 50a, 50b being subjected to stressing or relieved of stressing.

(13) The torsion springs 50a, 50b enclose the blocking surface 40 by way of their in each case 1.5 windings (corresponding to approximately 540). The torsion springs 50a, 50b here are coordinated with the diameter of the blocking surface 40 such that, in the absence of an external torque acting on the legs, the springs assume a relieved-of-stressing state, in which they are pressed onto the blocking surface 40. This constitutes the blocked state. In the absence, therefore, of any torque which acts to spread apart the legs 52a, 52b, the torsion springs 50a, 50b block a rotary movement of the seat unit 10 in relation to the base 20.

(14) In order to achieve the freeing action, the displaceable legs 52a, 52b have to be spread apart from one another. A switching carriage 60 is provided for this purpose, and said carriage can be displaced in the axial direction depicted by the arrow 4. The switching carriage 60, for this purpose, is provided with a slot 62, through which project two screws 63 which have been screwed into the seat-side bearing device. The switching carriage 60 has two axially offset switching slopes 64a, 64b, which are inclined in opposite directions and against which the spring legs 52a, 52b butt. The switching slopes here have an angle of approximately 45 in relation to the vertical. Although other angles are also conceivable here, in principle, it is nevertheless advantageous if the switching slopes 64a, 64b are angled such that there is no self-locking taking place in either direction of action: it is desired for displacement of the switching carriage 60 to be able to spread apart the spring legs 52a, 52b and for the legs 52a, 52b to be able to initiate an axially acting force in the switching carriage 60, so that the latter can be restored.

(15) FIGS. 3a and 3b show the freed state of the blocking device. This state is achieved when the switching carriage 60 is located in a lower end position, in which the legs 52a, 52b are arranged in each case in the region of the upper ends of the switching slopes 64a, 64b. The legs have thus been spread apart from one another. The windings of the springs 50a, 50b no longer butt with clamping action against the blocking surface 40. The lower end position of the switching carriage 60 is brought about by a transverse crossmember 18 of the seat unit 10, this acting on the switching carriage 60 from above and not allowing the switching carriage to yield upwards in the freed position of FIGS. 3a and 3b.

(16) In the absence of this downwardly directed force activation of the switching carriage 60, the situation shown in FIGS. 4a to 4c is established. The switching carriage 60 is displaced upwards in the direction of the arrow 4a, since the legs 52a, 52b at the end of the torsion springs 50a, 50b attempt to assume their relatively relieved-of-stressing position shown in FIGS. 4a to 4c. Via the switching slopes 64a, 64b, the legs here push the switching carriage 60 upwards. In the state shown in FIGS. 4a to 4c, the windings of the torsion springs 50a, 50b are therefore tighter and butt with clamping action against the blocking surface 40. Rotary movement of the seat unit 10 in relation to the base 20, then, is possible only with great difficulty, if at all.

(17) FIGS. 5a and 5b depict how the blocked state shown in FIGS. 4a to 4c is brought about. The figures show the piece of seating furniture with the standing-up aid activated. This standing-up aid can pivot a multiplicity of components of the seat unit 10 in the manner illustrated. These components also include the aforementioned transverse crossmember 18, which is raised out of its starting position 18, indicated by dashed lines in FIG. 5a, and thus loses contact with the switching carriage 60. Consequently, the latter yields upwards, in the manner already described, and establishes the blocked state of the blocking device. Activation of the standing-up-aiding function thus also gives rise as it were automatically, without any separate switching operation being required, to blocking of the blocking device.

(18) FIGS. 6a and 6b show an alternative form of blocking device. The latter, instead of the carriage 60 having the switching slopes 64a, 64b, has two switching levers 65a, 65b, which are fitted such that they can be pivoted about axes 67a, 67b in relation to the seat-unit-side bearing device 32. The spring legs 52a, 52b of the torsion springs 50a, 50b, said legs acting as torque-inducing portions, are secured at the respectively lower end of said switching levers 65a, 65b. The respectively upper end of the switching levers is provided with a coupling portion 66a, 66b, it being possible for the switching levers 65a, 65b to be pivoted by the force activation of said coupling portion.

(19) In a manner similar to the switching carriage 66 described, the switching levers 65a, 65b are actuated via the transverse crossmember 18. The blocking device is released by virtue of the transverse crossmember 18 being lowered. If the transverse crossmember 18 is raised, then it is possible for the torsion springs 50a, 50b, with the switching levers 65a, 65b being pivoted at the same time, to resume their relatively relieved-of-stressing state, in which they butt against the blocking surface 40 and thus shift the blocking device into the blocked state.