Technical field

[0001] The present invention relates generally to a chair with a tiltable and lockable seat cushion according to the preamble of patent claim 1.

Background art

[0002] For chairs it is known to arrange the seat cushion tiltable in all directions. Such tiltable seat cushions are for example useable on chairs comprising a centrally placed support leg, such as regular office chairs, stools or so called saddle chairs. A tiltable seat cushion provides a correct seating position for the user, because it adapts to the motions of the user. A certain instability in the seat cushion also activates certain muscles of the user, which may contribute to an increased muscle strength and decreased ache in the back and neck.

[0003] In patent application W01996024274 it is for example disclosed a stool where the seat cushion is attached to a support leg comprising a semi-spherical foot resting on the ground. The seat and support leg pendulate around the ground contact surface of the support leg.

[0004] In US6209958 another solution is disclosed where the seat cushion rests on a spherical joint arranged in the top part of the support leg, which make a pendulating motion of the seat cushion possible in all directions. The tilting motion inertia is determined by an elastomeric spring arranged concentrically around the support leg. The seat cushion is also lockable in all positions by pressing the elastomeric spring towards the spherical joint.

[0005] During certain circumstances it may be desirable to be able to lock the seating cushion in a basic position where the main seat surface is horizontal.

Summary of invention

[0006] An object of the present invention is to provide a chair which makes a pendulating seat cushion motion in all directions possible and which is easy to maneuver and lock in a basic position. [0007] The above mentioned object is according to the invention met by a chair according to the characterizing part of patent claim 1. The inventive chair comprises a seat cushion and an essentially centrally below the seat cushion arranged support leg. It also comprises a joint comprising a first joint part fixedly connected to the seat cushion and a second joint part fixedly connected to the support leg and a spring arranged concentrically around the support leg , acting between the seat cushion and a, in the support leg attached, spring support. The spring is adapted to straighten the seat cushion up to an essentially horizontal basic position and to provide a counter force to the tilting. The invention is characterized in that the first joint part comprises a through-going locating hole in which a pin is moveably arranged, where the pin has a first end which is arranged to be vertically moved into a locking hole arranged essentially concentrically with the center axle of the support leg to lock the seat cushion in an essentially horizontal basic position.

[0008] When using this construction the chair may easily be locked in an essentially horizontal basic position. Since the pin rotates with the first joint part when it is not in the locked position, the tilting of the seat cushion is not prevented. Additionally, no sitting forces act directly on the pin. Instead they are absorbed in the spherical joint. This makes it possible to lock the position of the chair also when a person is seated on the chair.

Brief description of drawings

[0009] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

[0010] Fig. 1 shows a chair with a tiltable seating cushion [0011] Fig. 2 shows a cut view of the inventive chair comprising a locking pin. [0012] Fig. 3a-c shows locking pin in three different locked positions. [0013] Fig. 4 shows an alternative embodiment of the locking pin. Description of embodiments

[0014] In the following, a detailed description of invention is disclosed.

[00 5] Fig. 1 shows a chair 1 comprising a seat cushion 2 and an essentially centrally below the seat cushion 2 arranged support leg 3. A spring 4 is arranged essentially concentrically around the support leg 3. The spring 4 rests in its lower end on a spring support 5 and acts in its upper end on a support plate 6 which the seat cushion 2 is firmly attached to. The spring is adapted to straighten the seat cushion 2 up to a basic position, which means an essentially horizontal position on the support plate 6 when no one uses the chair, and to provide a counter force to the tilting when a person is seated on the seat cushion 2. .The support leg 3 of the chair may extend all the way to the ground, but it is also possible that it may be attached to a frame part, resting on the ground, comprising for example one or more, not disclosed, legs, wheels or other support arrangements.

[0016] In the support leg it may be arranged a height adjustment arrangement 13 adapted to adjust the length of the support leg. Preferably, the height adjustment device 13 is a gas spring or a similar arrangement where the pressure can be adjusted by adjustment of a valve position 14.

[0017] Figure 2 shows a cut view of the chair and its seat cushion 2. The seat cushion 2 is attached to the support plate 6, which in turn is connected to a joint 8. The joint 8 comprises a first joint part 8a fixedly connected to the support plate 6 and a second joint part 8b fixedly connected to the spring support 5, which in turn is attached to the support leg 3. The first joint part 8a has a cut spherical shape with a ring shaped convex sliding surface 8a'. The second joint part 8b, which is fixedly connected to the spring support 5, has a cylindrical shape with an essentially horizontally arranged inner ring shaped concave sliding surface 8b'. The sliding surfaces 8a', 8b' are arranged to slide against each other.

[0018] The first joint part 8a also comprises a through-going locating hole 9 in which a pin 10 is moveably arranged. The pin 10 has a first end 0a, which is adapted to be moved vertically into a locking hole 11 arranged essentially concentrically with the center axle z of the support leg 3. In order to decrease the stress on the first joint part 8a, a guide sleeve 12 is inserted into the locating hole 9. This guiding sleeve 12 is attached to the support plate 6.

[0019] The pin 10 is connected to an adjustment arrangement 7, having the shape of a lever (see also fig. 1 and 3a-c), by which the vertical position of the pin 10 is adjusted in relation to the locating hole 9. The lever 7 is articulatedly connected to the second end 10b of the pin and is rotatable around a point z, located between the two ends of the lever 7. This point z may be an attachment attached to the support plate 6. By moving the lever 7 upwards and downwards, respectively, the pin is moved in the opposite direction.

[0020] The pin 10 can be locked in at least two positions with one or several spring supported pegs 15, which interconnect with cavities 16 in the pin 10.

[0021] In figure 3a-c three locked positions of the pin 0 is shown; a first position where the pin 10 is free from the locking hole 11 , a second position where the pin

10 is inserted into the locking hole 11 a first distance s1 and a third position where the pin 10 is inserted into the locking hole 11 a second further distance s2 and is therefore interacting with the height adjustment device 13. It is also possible to adjust the height of the chair in other ways. Then the pin 10 has only two locked positions; one first position where the pin 10 is free from the locking hole 11 and a second position where the pin 0 is inserted into the locking hole 1 .

[0022] Figure 4 shows an alternative embodiment of the locking arrangement comprising the pin 10 and the locking hole 11. 1 this embodiment the locking hole

11 has a conical opening which decreases in diameter in a direction away from the pin 10. At the same time the pin 10 has a conical first end 10a which is inserted into the locking hole 11. By using a conical shape on the hole 11 and the pin 10, the locking of the chair in the upright basic position is facilitated since the conical surfaces guide the pin into the hole

[0023] In figure 4, the adjustment device 7, by with the vertical position of the pin 10 is adjusted, comprises a through-going hole in which a separate first activation part 7 is moveably arranged, which is adapted to act on a one in the pin arranged moveable second activation part 18, which in turn actuate the height adjustment device 13.

[0024] The invention is not limited to the described embodiments, but can be freely varied within the scope of the patent claims. The features described in the different embodiments may be combined unless it is directly contradictory.

[0025] The expression "chair" includes all types of seating arrangements comprising a seat and one under this, essentially centrally arranged, support leg, such as regular office chairs, stools or so called saddle chairs. The support leg does not necessary need to extend all the way to the ground, but can instead be attached in one, on the ground resting, frame part comprising for example several legs, wheels or other support arrangements.

[0026] The expression "seating cushion" comprises arrangements in one or several pieces which may be hard or soft, i.e. the expression includes a seating cushion in one or several pieces of hard plastic as well as a seating cushion with a hard support unit and one thereupon arranged soft cushion.