Piece of furniture and adjusting assembly, in particular for adjusting a back of a chair

Abstract

The present invention relates to a piece of furniture comprising at least one adjustable use portion, in particular an office chair having an adjustable seat and/or an adjustable backrest. The present invention further relates to an adjusting assembly that can be used, for example, for a piece of furniture of said type.

Claims

1. Piece of furniture comprising at least one adjustable use portion having a drive unit comprising an electric motor, an adjustment device driven by the drive unit for adjusting a height or tilt of the use portion, and a coupling arranged between the drive unit and the adjustment device, which coupling introduces driving force from the drive unit into the adjustment device when in a closed state and stops force being transmitted between the drive unit and adjustment device when in an open state, wherein the coupling comprises a first coupling element, which is associated with the drive unit, and a second coupling element, which is associated with the adjustment device, the first coupling element and the second coupling element being connected for conjoint rotation when the coupling is closed and the first coupling element and the second coupling element being separated when the coupling is open.

2. Piece of furniture according to claim 1, wherein, when the coupling is open, the adjustment device can be adjusted manually by exerting a force on the use portion.

3. Piece of furniture according to claim 1, wherein the adjustment device comprises a resilient spring means which biases the adjustment device in an adjustment direction, at least when the coupling is open.

4. Piece of furniture according to claim 1, wherein the adjustment device comprises a force conversion mechanism which exerts a rotational force on the second coupling element when the user exerts an operating force on the use portion, the force conversion mechanism limiting this rotational force to a predefined maximum rotational force, and the predefined maximum rotational force being smaller than a turn-over force of the drive unit in the passive state.

5. Piece of furniture according to claim 4, wherein the adjustment device comprises a threaded spindle drive which is rotated when the coupling is open by the user exerting an operating force on the use portion and which enters a self-locking state when the coupling is closed.

6. Piece of furniture according to claim 1, wherein the coupling comprises an actuator that moves the coupling between the open position and closed position on the basis of an electrical signal, the actuator preferably consuming electrical energy substantially only for the operation for switching the coupling between the open position and the closed position, and the coupling being designed to maintain set position without consuming electrical energy.

7. Piece of furniture according to claim 1, wherein the piece of furniture is an office chair that comprises: a base, a seat, a chair column that extends in the vertical direction between the base and the seat, and a backrest, and the adjustable use portion including the seat and/or the backrest and/or an armrest.

8. Piece of furniture according to claim 1, wherein the adjustment device is a first adjustment device of a plurality of adjustment devices, and in that a second adjustment device is also provided for adjusting an additional positional parameter of the use portion and/or for adjusting the height or tilt of an additional use portion of the piece of furniture, a gearing being arranged between the drive unit and the first adjustment device, which gearing is designed to introduce driving force from the drive unit into the second adjustment device such that the two adjustment devices can be driven by a common drive unit.

9. Adjusting assembly for a use portion of a piece of furniture, comprising: a drive unit having an electric motor, an adjustment device driven by the drive unit, and a coupling arranged between the drive unit and the adjustment device, which coupling introduces driving force from the drive unit into the adjustment device when in a closed state and stops force being transmitted between the drive unit and adjustment device when in an open state, wherein the coupling comprises a switch element that can be moved by means of magnetic force in order to switch the coupling between the closed state and the open state, wherein the coupling comprises a first coupling element, which is associated with the drive unit, and a second coupling element, which is associated with the adjustment device, the first coupling element and the second coupling element being connected for conjoint rotation when the coupling is closed, and the first coupling element and the second coupling element being separated when the coupling is open, and the switch element being formed by the first or second coupling element.

10. Adjusting assembly according to claim 9, wherein the coupling comprises an actuator that moves the coupling between the open position and the closed position on the basis of an electrical signal, the actuator preferably consuming electrical energy substantially only for the operation for switching the coupling between the open position and the closed position, and the coupling being designed to maintain set position without consuming electrical energy.

11. Adjusting assembly according to claim 10, wherein the actuator comprises an electromagnet, which generates an electromagnetic field for moving the switch element on the basis of the electrical signal.

12. Adjusting assembly according to claim 9, wherein the coupling is held in the open position or in the closed position by the force of at least one permanent magnet, in particular a first permanent magnet being provided to hold the coupling in the closed position, and a second permanent magnet being provided to hold the coupling in the open position.

13. Piece of furniture, comprising an adjusting assembly including at least one adjustable use portion having a drive unit comprising an electric motor, an adjustment device driven by the drive unit for adjusting a height or tilt of the use portion, and a coupling arranged between the drive unit and the adjustment device, which coupling introduces driving force from the drive unit into the adjustment device when in a closed state and stops force being transmitted between the drive unit and adjustment device when in an open state, wherein the coupling comprises a switch element that can be moved by means of magnetic force in order to switch the coupling between the closed state and the open state, wherein the coupling comprises a first coupling element, which is associated with the drive unit, and a second coupling element, which is associated with the adjustment device, the first coupling element and the second coupling element being connected for conjoint rotation when the coupling is closed, and the first coupling element and the second coupling element being separated when the coupling is open, and the switch element being formed by the first or second coupling element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a transparent side view of an office chair according to an embodiment of the present invention,

(2) FIGS. 2a and 2b are functional views of an actuation device of the embodiment of the invention in a position with the coupling open (FIG. 2a) and the coupling closed (FIG. 2b).

DETAILED DESCRIPTION

(3) An office chair denoted in general by 10 in FIG. 1 is an embodiment of a piece of furniture according to the present invention, which will be described below in more detail. The office chair 10 comprises a seat 12, a base 14, a chair column 16 extending in the vertical direction between the seat 12 and the base 14, and a backrest 18. As is common for office chairs, the chair column 16 is provided as the single central column for connecting the base 14 and the seat 12. One or more support elements, for example in the form of chair casters 20, can be provided on the base 14 for support against the floor. The seat 12 can have upholstery 22, which can be held on a seat shell 24. The backrest 18 can also have upholstery (not shown). Preferably, the seat 12 is mounted so as to be freely rotatable with respect to the base 14 about the vertical axis of the chair column 16, as is also known per se for office chairs.

(4) The backrest 18 is attached to the seat 12 and held in a pivotable manner on a preferably horizontal pivot pin 28 so as to be able to adjust a tilt of the backrest 18 relative to the seat 12. In the embodiment shown, a bracket 30 that has a hinge portion 32 and is rigidly connected to the seat 12, in particular to the seat shell 24, is provided, on which bracket the pivot pin 28 of the backrest 18 is mounted. A spring element 34 is provided on the pivot pin 28 such that the backrest 18 is biased into an upright position or in a direction towards the seat 12. The spring force direction of the spring element, which is preferably formed as a torsion spring about the pivot pin 28, is indicated in FIG. 1 by an arrow A.

(5) The office chair comprises an adjustment device 36 for adjusting a tilt of the chair back 18, and an electric-motor drive unit 38, which is coupled to the adjustment device 36 such that the backrest 18 can be adjusted by the force of the drive unit. In the process, the drive unit 38 can comprise an electric motor 40 and an energy source 42, which is preferably formed by a rechargeable or non-rechargeable battery. Alternatively, the electric motor can be supplied with energy by a power grid.

(6) The adjustment device 38 comprises a threaded drive assembly having a threaded spindle 44, which comprises an external thread that engages in an internal thread of a threaded cylinder 46. If the threaded spindle 44 and the threaded cylinder 46 are rotated relative to one another by the force of the electric motor 40, the axial length of the threaded drive assembly is lengthened or shortened. This linear actuation movement is transmitted to the backrest 18 via a joint 48, the joint 48 being provided at a distance from the pivot pin 28 such that the linear actuation movement of the threaded drive assembly can be converted into a pivot movement of the backrest 18. To integrate the adjustment device 36 in the region of the seat 12 in an inconspicuous manner, the stop 48 of the backrest 18 is advantageously below the pivot pin 28. Alternative gearing elements are conceivable for converting the actuation movement of the threaded drive assembly into a pivot movement of the backrest, for example by gearwheel transmission, belt or chain transmission, or the like.

(7) According to the invention, a coupling 50 is arranged between the adjustment device 36 and the drive unit 38, which coupling introduces driving force from the drive unit 38, i.e. a rotational force from the electric motor 40, into the adjustment device 36 when in the closed state, i.e. in particular causes one of the two elements out of the threaded spindle 44 and threaded cylinder 46 to rotate relative to the other, whilst transmission of force is stopped between the drive unit 38 and the adjustment device 36 when the coupling is in the open state. The design and action of a preferred example of a coupling 50 of this type will be explained in more detail below with reference to FIGS. 2a and 2b.

(8) The coupling 50 preferably comprises a first coupling element 52 on the drive side, which is connected for conjoint rotation to an output shaft 54 of the electric motor 40, and a second coupling element 56, which is connected for conjoint rotation to the adjustment device 36. In this embodiment, the adjustment device 36 comprises the threaded drive assembly and the second coupling element 56 is, for example, connected for conjoint rotation to the threaded spindle 44.

(9) The first coupling element 52 and the second coupling element 56 can be displaced relative to one another in the axial direction of the motor output shaft 54 such that they can be adjusted between a state with the coupling open according to FIG. 2a, in which the first coupling element 52 and the second coupling element 56 are spaced apart from one another, so no rotational force is transmitted between the coupling elements 52 and 56, and a state with the coupling closed according to FIG. 2b, in which the coupling elements 52, 56 are brought towards one another and connected for conjoint rotation, so rotational force can be transmitted between the coupling elements 52, 56. In the embodiment shown, this adjustability of the coupling 50 is produced, for example, by the second coupling element 56 comprising a pin 58 that has an axial serration 60 which engages in a corresponding serration (not shown) of the threaded spindle 44, and so the second coupling element 56 is coupled to the threaded spindle 44 for conjoint rotation but so as to be axially displaceable. Alternatively, the second coupling element 56 could be mounted on its pin 58 for conjoint rotation but so as to be axially displaceable.

(10) The movement of the second coupling element 56 into the closed state is limited by the second coupling element 56 coming into contact with the first coupling element 52. Movement of the second coupling element 56 in the opposite direction towards the open state is limited by a coupling opening stop 62, which is preferably arranged around the pin 58 of the second coupling element 56 as a coaxial disc. Preferably, the coupling opening stop 62 is arranged so as to be rotatable about the pin 58 together with the second coupling element 56, yet is held so as to be axially immovable relative to the first coupling element 52. When the coupling is open, the second coupling element 56 and the coupling opening stop 52 thus abut one another and rotate together.

(11) In the embodiment shown, the coupling 50 is moved between the open state and closed state by means of magnetic force. For this purpose, the first coupling element 52 preferably comprises a permanent magnet and the coupling opening stop 62 also comprises a permanent magnet. The second coupling element 56 can then be made of a magnetic material, for example a steel, so it is held robustly in both coupling states by the magnetic force of the stop body 52 or 62 in each case. To move the second coupling element 56 out of these positions, an electromagnet 64, for example in the form of a coaxial coil winding, is also provided on the first coupling element 52 and on the coupling opening stop 62. Each of the electromagnets of the first coupling element 52 and of the coupling opening stop 62 can be powered by a power supply device (not shown) and activated in such a way that it generates an electromagnetic field that is directed in the opposite direction to the magnetic field of each permanent magnet, and so the attractive force from this magnet is limited to the second coupling element or is even reversed into a repulsive force. If the second coupling element 56 is in contact with the coupling opening stop 62, for example in the position shown in FIG. 2a, and the electromagnet of the coupling opening stop 62 is operated such that it cancels out the field of the permanent magnet of the coupling opening stop 62, the second coupling element 56 lifts off the coupling opening stop 62 under the action of the attractive force of the permanent magnet of the first coupling element 52 and moves towards the first coupling element 52 until it comes into contact with said element and the coupling passes into the closed state according to FIG. 2b. Alternatively or additionally, this movement can be caused or supported by the electromagnet 64 of the first coupling element 52 being actuated accordingly and/or can be caused or assisted by the electromagnet of the coupling opening stop 62 being energised accordingly strongly in the sense of repelling the second coupling element 56.

(12) To switch the coupling 50 from the closed position into the open position, on the other hand, the electromagnet 64 of the first coupling element 52 can be activated such that the electromagnetic field thereof cancels out the magnetic field of the permanent magnet of the first coupling element 52, and so the second coupling element 56 is moved towards the coupling opening stop 62 by the force of the permanent magnet of the coupling opening stop 62 (and/or possibly by a force of the appropriately wired electromagnet of the coupling opening stop 62).

(13) After each switching operation, the energy supply to the electromagnets can be switched off, and the second coupling element 56 remains in the set coupling position owing to the force of the respective permanent magnet, meaning that electrical energy only has to be expended for the switching operation. The electrical energy can be provided by the energy source 42 that also powers the electric motor 40.

(14) Regardless of the specific design of the coupling 50, the decoupling according to the invention of the drive unit 38 and the adjustment device 36 enables a free-rocking function in the backrest 18. For this purpose, a thread pitch of the threaded spindle 44 or threaded cylinder 46 is selected such that, in a state with the coupling open (FIG. 2a), the second coupling element 56 is rotated when a force is exerted on the backrest 18 by the user in a direction counter to the arrow A and the threaded drive assembly is thus compressed, and in the process the coupling opening stop 62 in particular also rotates therewith. The thread pitch is also selected such that, when the backrest 18 is relieved of load, the force of the spring element 34 is sufficient to extend the threaded drive assembly, rotating the second coupling element 56 accordingly. When the coupling 50 is open, the backrest 18 can thus be manually pivoted backwards and forwards.

(15) If, on the other hand, the coupling 50 is closed, a rotational force of the second coupling element 56, caused by the user actuating the backrest 18 or by the spring element 34, is introduced into the electric motor 40 via the coupling 50. When the electric motor is switched off (passive drive unit), the electric motor 40 opposes a rotation introduced therein by a predefined turn-over force. Advantageously, the thread pitch of the threaded drive assembly 44, 46 is now selected such that, when force is input into the backrest 18 by the user or by the spring element 34, and specifically with the coupling 50 open, the second coupling element 56 is rotated and thus the backrest 18 is adjusted. However, when the coupling 50 is closed, the rotational force acting on the second coupling element 56 is smaller than the turn-over force of the electric motor 40, and so the rotation is blocked and in particular so too is adjustment of the threaded drive assembly 44, 46 and thus adjustment of the backrest 18. This state is referred to as self-locking, caused by the gearing speed reduction of the threaded assembly between the threaded spindle 44 and the threaded cylinder 46. A person skilled in the art would ascertain the suitable thread pitch for a particular specific adjustment system in a simple manner, for example by simple investigations by reducing the pitch of the thread of the threaded drive assembly 44, 46 in steps, starting from a very steep thread (high pitch), in which adjustment of the backrest 18 by the user exerting a manual force leads to the motor 40 turning over when the coupling is closed, until adjustment of the backrest 18 can no longer be adjusted or can only be adjusted by exerting an unusually high force on the backrest 18. As a measurement for ascertaining the suitable thread pitch, the automatic adjustment owing to the spring element 34 can also be applied. Therefore, when the coupling is open, free rocking is possible against the force of the spring element 34, while locking occurs when the coupling is closed and adjustment of the backrest 18 requires actuation of the electric motor.

(16) It should be noted at this juncture that the motor 40 can comprise an additional gearing 66, which reduces or increases the speed of the motor to a speed of the output shaft 54. The gearing 66 can in particular also influence the turn-over force of the motor 40. Even though the gearing 66 can also be provided to be largely separate from a stator of the motor 40, it may be considered to be a part of the motor 40 for illustrative purposes in the context of the present application.

(17) It can also be seen in FIG. 1 that, in addition to the adjustment device 36 of the backrest 18, the drive unit 38 can also drive a second adjustment device 68 for adjusting a height of the seat 12 over the base 14. The second adjustment device 68 can also comprise a threaded drive assembly having a threaded spindle 70 and a threaded cylinder 72, it being possible for the threaded drive assembly to be inserted into the chair column 16 coaxially in the vertical direction such that rotation of the threaded spindle 70 into or out of the threaded cylinder 72 leads to compression or expansion of the threaded drive assembly and thus to the height of the seat 12 being adjusted. The rotational force necessary for adjusting the threaded drive assembly 70, 72 can be introduced from the electric motor 40 into the second adjustment device 68 via a bevel gear transmission, in order to make an angle possible between the axes of rotation of the first adjustment device 36 and the second adjustment device 68. For this purpose, a first bevel gear 74 can be drivable by the electric motor 40 and can mesh with a second bevel gear 76, which is connected to the threaded spindle 70 or the threaded cylinder 72 for conjoint rotation.

(18) Furthermore, a change gear may also be provided for alternately and optionally transmitting the force of the motor 40 to the first adjustment device 36 to adjust the backrest 18 or to the second adjustment device 68 to adjust the seat height. In a simple variant of a change gear of this type, the output shaft 54 of the electric motor can be displaceable in the axial direction, and can be engaged, via an axial serration (not shown), with either the first coupling element 52 or the first bevel gear 74 for conjoint rotation but so as to be axially displaceable. To adjust the backrest 18, the motor output shaft 54 is then, for example, inserted into an axially toothed central opening in the coupling element 52 in order to rotationally drive the first coupling element 52, while the motor output shaft 54 is then retracted from the first bevel gear 74. The electric motor 40 then only drives the adjustment device 36 of the backrest 18. Conversely, the motor output shaft 54 can be displaced axially into an opening in the bevel gear 74 provided with a corresponding axial toothing, such that said shaft drives the first bevel gear 74 and thus the second adjustment device 68 in order to adjust the height of the seat 12, while the motor output shaft is then disengaged from the first coupling element 52 and thus does not rotationally drive the first coupling element 52.

(19) As can be seen in FIG. 1, the drive unit 38 (optionally including batteries 42), the coupling 50 and important parts of the adjustment device 36 and change gear can be housed in the seat 12 of the office chair 10, and so effective use is made of the space therein. At the same time, an essential part of the adjustment device 68 can advantageously be housed in the chair column 16.

(20) An operating unit 78 can also be provided on the seat 12 or on another element of the office chair 10, or can be provided separately from the office chair 10 and connected by means of cables or wireless communication, which unit converts manual inputs from the user into corresponding control signals for actuating the drive unit 38, the coupling 50 and optionally the change gear. The operating unit 78 can be formed by a smartphone on which a suitable program code is stored for transmitting control signals to a wireless receiver unit (not shown) of the office chair 10, the drive unit 38 and/or the coupling 50 being actuated on the basis of signals received by the wireless receiver unit from the smartphone.