[0001] The object of the invention is a swivel mechanism for the seat of an upholstered piece of furniture, facilitating the adoption of the correct anatomical position for a seated person, in particular for the lordosis section of the spine subject to degeneration.

[0002] A rotary mechanism is known from European patent description EP1000569. The mechanism consists of two profiled plates moving horizontally relative to each other through friction-reducing bearing balls. Introduction into motion is by means of a handle mounted on a conical wedge, and movement takes place about a central axis concentrically aligning the lower and upper plates. The disadvantage of this solution is the additional element in the form of the handle, which must be offset from the seat of the furniture, which reduces the visual quality of the furniture. The second disadvantage is the use of bearing balls set close to the axis of rotation, which implies the use of only seats with specific dimensions. The use of larger sized seats causes the whole mechanism to sway.

[0003] Also known from Japanese patent description JP2009142364 is a mechanism based on a rotating conus mechanism. The conus, as the main supporting and rotational axis, is coupled by means of turnbuckles or actuators to the raised seat. Rotation of the seat is carried out by means of applied human force with the help of guide wheels located at the bottom. As in the previous solution, the disadvantage is the central pivot that prevents proper seating of the seat springs. The main disadvantage of this design is the visible components of the mechanism.

[0004] Also known from the Polish utility model description Ru.062376 is a mechanism slightly modified in comparison with the invention EP1000569A1 consisting of two plates separated by bearing balls. The upper plate and the lower plate are axially fixed to each other at the intersection of the symmetry axes of both plates. As in Japanese description JP2009142364, the disadvantage is the central axis of rotation preventing proper seating of the seat springs, which will increase the acoustics of the furniture under the pressure of the user. An additional disadvantage is the inability to use larger sized seats as this results in a loss of stability of the mechanism, causing additional friction in the mechanism.

[0005] From the Polish patent description PL216214 is known a mechanism that also consists of two plates, but compared to the previous solutions the axis of rotation is located outside the symmetry axes of both plates. The main advantage is the displacement outside the center of rotation, which makes it possible to reduce the size of the seat foam and upholstery. However, the main disadvantage, as before, is the plate against which, under the pressure of the user, the springs will strike, increasing the acoustics of the furniture. Additionally, this solution lacks the possibility of locking in extreme positions, which is extremely important when using the furniture.

[0006] The seat swivel mechanism for upholstered furniture consists of a rectangular top frame and a bottom frame. Two sliders, one for each arm respectively, are attached to the rectangular upper frame on two adjacent arms on their bottom surface. The sliders have longitudinal ball-shaped cavities along their entire length at the bottom. On one of the other arms of the top frame there is a rectangular projection in the plane of the top frame, to the lower surface of which tabs with sliders are attached.

[0007] The base frame has five arms and has two broader arms at right angles to each other and two narrower arms at acute angles to each other, connected by a fifth arm. On the arms at right angles to each other there are fixed on their upper surfaces linear guides of L-shaped cross-section with longitudinal tabs of circular profile. On the wider arms of the base frame there are two curved guides, one for each arm respectively. In addition, on the wider arms of the base frame, there are two oval windows, one for each arm respectively.

[0008] Preferably, a pin is attached to the slider of the upper frame.

[0009] Preferably, between the pin and the upper frame there is a sliding sleeve aligned axially with the pin. [0010] Preferably, between the tabs of the upper frame and the curved guides of the lower frame there are rubber dampers.

[0011] Preferably, the longitudinal ball-shaped cavities of the upper frame slider have a greater clearance in relation to the longitudinal linear tabs of the guides.

[0012] The lower frame is fixed to the furniture and the upper frame is fixed to the seat.

[0013] The top frame, which is open on the inside, facilitates the assembly and use of the seat springs, so that the seat springs bend freely without unnecessarily increasing the acoustics of the furniture.

[0014] The rectangular upper frame moves parallel to the lower frame in a reciprocating motion along a circular path with an angle of 90°. The movement of the upper frame is determined on one side by sliders which move along linear guides of "L" cross-section with longitudinal insets of circular profile. The opposite part of the upper frame is locked by sliders from below and by insets from above, clasping against two curved guides. The longitudinal ball-shaped cavities of the top frame slider have greater clearance than the longitudinal linear insets of the guides, allowing slight rotation of the sliders, which are fixed to the top frame, while the opposite part of the top frame with insets moves along a track in the shape of a an oval section. The movement of the insets in the horizontal position is unlimited parallel to the base frame. The movement of the insets in the vertical position is restricted both from above and below. Restriction from above is provided by two curved guides. The bottom frame movement is limited from below by means of glides screwed to the insets. All movement of this part of the upper frame is carried out by the movement of the glides on the lower frame. However, in extreme settings of the swivel joint (0° and 90° angle) with the axis of rotation outside the central axis, through the windows into which the sliders fall, under the influence of gravity resulting from the seat, the foams, the user and the assembly of elements itself, the swivel mechanism is blocked.

[0015] The swivel mechanism allows the upper frame to rotate by 90°, occupying two extreme positions relative to the stationary lower frame. In one extreme position the user is in a semi-recumbent/reclining position, in the other extreme position the user is in a sitting position. In both extreme positions, the mechanism locks by gravity under the influence of the weight of the foams and the user. According to the state of the art, in most cases the axis of rotation of the mechanism runs perpendicular to the point of intersection of the axes of symmetry. This creates a central axis, inside the mechanism, around which the points of the mechanism move along a track of constant radius. In the present invention, thanks to the applied new construction of the rotary mechanism, the momentary axis of rotation is remote from the set of elements, which allowed to reduce the dimensions of the upholstered seat screwed to the mechanism. This also made it possible to use a top frame open from the center, which implies a reduction in the acoustics of the seat springs hitting the top plane of the mechanism.

[0016] The object of the invention in the embodiment is shown in the drawing where Fig. 1 shows the mechanism in top view, Fig. 2 shows the mechanism responsible for blocking the movement in vertical position in side view, Fig. 3 shows the cross-section of the mechanism responsible for the movement of the slider in straight line in side view, Fig. 4 shows the detail of the tabs blocking the upper frame in vertical movement, Fig. 5 shows the rotary mechanism in perspective view.

[0017] The seat swivel mechanism of an upholstered furniture consists of a rectangular upper frame 1 and a lower frame 2. To the rectangular upper frame 1, on two adjacent arms, on their lower surface, two sliders 10 are fixed, respectively, one for each arm. The sliders 10 along their entire length are provided with longitudinal ball-shaped cavities 10a at the bottom. On one of the other arms of the upper frame 1 there is a rectangular protrusion 13 in the plane of the upper frame 1, to the lower surface of which there are fixed insets 13a with sliders 14.

[0018] The bottom frame 2 is five-armed and has two wider arms perpendicular to each other and two narrower arms positioned towards each other at an acute angle, connected by a fifth arm. On the arms positioned towards each other at acute angles, linear guides 5 and 6 of L- shaped cross-section with longitudinal insets 8 of circular profile are mounted on their upper surfaces. On the wider arms of the base frame 2 there are two curved guides 3 and 4 respectively, one for each arm. Furthermore, on the wider arms of the base frame 2 there are two oval windows 15 respectively one for each arm. The longitudinal ball-shaped cavity 10a of the slider 10 of the upper frame 1 have greater clearance with respect to the longitudinal inset 8 of the linear guides 5 and 6. The lower frame 2 is fixed to the furniture and the upper frame 1 is fixed to the seat.

[0019] Upper frame 1 open from the inside facilitates the installation and use of the seat springs, so that the seat springs bend freely without unnecessarily increasing the acoustics of the furniture.

[0020] The rectangular upper frame 2 moves parallel to the lower frame 1 in reciprocating motion in a track of circular section, with an angle of 90°. The movement of the upper frame 2 is fixed on one side by sliders 10, which move along linear guides 5 and 6 of "L" cross- section with longitudinal insets 8 of circular profile. The opposite part of the upper frame 1 is locked by sliders 14 from below, and by insets 13a from above, clasping against two curved guides 3 and 4. The longitudinal ball-shaped cavities 10a of the slider 10 of the upper frame 1 have a greater clearance with respect to the longitudinal insets 8 of the linear guides 5 and 6 which allows a slight rotation of the sliders 10, which are fixed to the upper frame 1. On the other hand, the opposite part of the upper frame 1 with the insets 13a moves along a track in the shape of an oval section. The movement of the insets 13a in the horizontal position runs without restriction parallel to the bottom frame 2, while the movement of the insets 13a in the vertical position is restricted both from above and from below. Restriction from above is realized by two curved guides 3 and 4. The bottom plate 2, by means of sliders 14 screwed to the insets 13a, restricts movement of the upper frame 1 from below. All movement of this part of the upper frame 1 is carried out through the movement of the sliders 14 along the lower frame 2. However, in the extreme settings of the swivel joint (angles 0° and 90°) with the axis of rotation outside the central axis, through the windows 15 into which the sliders 14 fall, under the influence of gravity resulting from the seat, the foams, the user and the assembly of elements itself, the swivel mechanism is blocked.

[0021] An "L"-shaped linear rail 6 is attached by its lower surface 7 through bolts 9 to the flat bottom frame 2. Similarly, the rail 5 is a mirror image of the rail 6. The slider 10 is made in a larger tolerance around the inset 8 which allows the slack and the pin 11 attached to the slider 10 to establish a quasi-concentric position by a spherical selection 10a of the slider 10 against the inset 8 reducing friction during movement of the top frame 1 relative to the bottom frame 2. The pin 11 of the slider 10 is connected to the top plate 1 by means of a nut 18. In addition, in order to eliminate free spaces and friction between the pin 11 and the top frame 1, a sliding sleeve 17 is used. The sliding sleeve 17 is axially aligned with the pin 11. The sliders 10 fix one part of the upper frame 1, the insets 13a determine the movement of the opposite part of the upper frame 1. The insets 13a move by means of sliders 14 fixed to the insets 13a by means of screws 9 along the bottom plate 2. The upward movement of the insets 13a is limited by means of guides 3 and 4 forming an oval-shaped path. In order to avoid excessive acoustics between the insets 13a and the guides 3 and 4, rubber dampers 16 are used. In order to lock the end positions (0° and 90° angles of the movement path), oval cut-outs 15 in the bottom frame 2 are used. During the movement of the sliders 14 along the bottom frame 2 and when reaching the end position, the sliders 14 slide into the free space of the window 15 and remain there restrained by the raised plane of the bottom frame 2. The mechanism is locked in the end position until the upper frame 1 is mechanically positioned back on the sliders 14 on the plane of the lower frame 2. The lower frame 2 is connected to the furniture by nuts 19, and the upper frame 1 is connected to the seat through holes 12