BACKGROUND

The invention relates to a folding chair with a height adjustable seat part, comprising a frame having front legs and rear legs, said seat part having a first seating surface and an opposite second seating surface, which seat part is attached to the frame so as to be rotatable from a first position, in which the first seating surface is in a position of use, to a second position, in which the second seating surface is in a position of use, and vice versa. Such a folding chair is known from International patent application WO 2005/004674 to Applicant. The seating height of the chair may be adjusted by adjusting the position of the seat part relative to the frame. The seat may be locked into a high position to prevent rotation of the seat part when pressure is applied on the front edge of the seat. However, no measures are taken to prevent accidental rotation of the seat part when it is in a low position.

French Patent 74 07280 shows a locking mechanism for a rotatable seat of a chair, said locking mechanism directly engaging the axle of rotation. Both the axle and the locking mechanism must be sufficiently strong to withstand the torque exerted on the point of engagement between the axle and the locking mechanism. It is an object of the present invention to provide a folding chair with a height adjustable seat said chair comprising a locking mechanism of a simpler construction for locking the seat part into a number of different positions.

SUMMARY OF THE INVENTION

To this end, according to a first aspect, the present invention provides a folding chair with a height adjustable seat part, comprising a frame having front legs and rear legs, wherein the rear legs are hingeably connected to the front legs, and pivotable around an axis outside of the front legs between a folded position wherein the rear legs are substantially parallel to the front legs, and an unfolded position wherein the rear legs are at an angle to the front legs, said seat part having a first seating surface and an opposite second seating surface, which seat part is attached to the frame so as to be rotatable from a first position, in which the first seating surface is in a position of use, to a second position, in which the second seating surface is in a position of use, and vice versa, wherein the folding chair comprises two rotatable plates fixedly connected to opposing sides of the seat part, wherein each plate is connected to an axle extending from or into its proximate front leg, said axles being located outside of the plane of the seat part and defining an axis of rotation for the seat part, said rotatable plates being provided with a first abutment element and a second abutment element, wherein the rear legs are each provided with a lower stop adapted for abutment with the first abutment element when the seat part is in the first position, and an upper stop adapted for abutment with the second abutment element when the seat part is in the second position, wherein the folding chair is provided with a locking mechanism adapted for engaging the rotatable plate, i.e. at least one of said rotatable plates, at a distance from the axles for locking the seat part into the first and second positions. The same locking mechanism is thus adapted for locking the seat part in either the first or the second position. When the seat part abuts the lower or upper stops in the first or second positions, the force exerted on the locking mechanism during normal use, i.e. when a load is balanced on the seat and not placed on an edge thereof, will be small as the load is substantially supported by the axles and the upper or lower stops. Moreover, as the locking mechanism is adapted for engaging at least one of the rotatable plates at a distance from the axles instead of at the axles, the force exerted by the load on the locking mechanism will be relatively small. The axles are substantially free from torque when the seating part is in use.

In an embodiment the locking mechanism is further adapted for engaging said at least one of the rotatable plates for locking the seat part in a third position in which the first seating surface is substantially parallel to the front legs. When the rear legs of the chair are folded and the seat part is locked in the third position, the folding chair takes up substantially less space than when the seat part is in the first or second position. Transport and/or storage of the chair is thus facilitated.

In an embodiment the locking mechanism is comprised in the front legs, preferably on a side opposite to the rotatable plate. The locking mechanism can thus be easily reached by a person standing in front of the chair. Moreover, when the locking mechanism is placed in the front legs, the distance of the locking mechanism to the axis of rotation is constant, allowing the locking mechanism to be used independent of the position of the rear legs.

In an embodiment the folding chair is further provided with a first blocking mechanism comprising a first protrusion on the rear leg and a first blocking element on the rotatable plate, said first blocking element adapted for blocking hinging movement of the rear leg from an unfolded position to a folded position when the seat part is in the first position. Folding of the chair when the seat part is in the first position is thus prevented, especially when the seat part is locked in the first position.

In an embodiment the folding chair is further provided with a second blocking mechanism comprising a second protrusion on the rear leg and a second blocking element on the rotatable plate, said second blocking element adapted for blocking hinging movement of the rear leg from an unfolded position to a folded position when the seat part is in the second position. Folding of the chair when the seat part is in the second position is thus prevented, especially when the seat part is locked in the second position. Preferably the chair comprises a first and/or second blocking mechanism on both sides of the seat, i.e. on both the left side and right side when facing the chair in a position of use from the front. Alternatively, the first blocking mechanism may be provided on one side of the seat, e.g. the right side, and the second blocking mechanism may be provided on another side, e.g. the left side of the chair .

In an embodiment the rear- and front legs are adapted for keeping the chair in an upright position when in the folded position. Multiple such chairs may thus be conveniently stored standing next to each other.

In an embodiment the lower stop and the upper stop are formed as a single element arranged in line with the axis of rotation of the rear legs, preferably as a bolt forming part of a hinge between the front and rear legs. The upper and lower stops may thus conveniently be mounted to the chair during manufacture of the chair.

In an embodiment the rear legs comprise an abutment surface for abutting a side of the front legs when the chair is in the unfolded position, providing additional stability.

In an embodiment the locking mechanism comprises a locking element arranged for locking the rotatable plate for locking the seat part into the first and second positions. The same locking element is thus used for locking one of the two rotatable plates for locking the seat part into the first position, and for locking the seat part into the second position.

In an embodiment each of front legs comprises a locking mechanism, preferably such that both locking mechanisms have to be operated simultaneously for unlocking the seat part from the first, second or this position. Thus two hands are needed to operate the locking mechanisms, avoiding accidental pivoting of the seat part, especially when someone is sitting on the seat.

In an embodiment the locking mechanism comprises a slidable pin in line with the axis of rotation of the rotatable plate and provided on one side with a button or handle, and provided on another side with an engagement arm for engaging the rotatable plate, i.e. at least one of the rotatable plates, to lock it in the first, second or third position, said engagement arm being rotationally fixed with respect to the front leg, and said slidable pin at least partially extending through a through passage in the front leg. Preferably the engagement arm and/or the pin axle is pre-tensioned for engaging the rotatable plate. The locking mechanism may thus be integrated in an axle, without actually engaging the axle for locking the seat part in the first or second position. In a preferred embodiment the locking mechanism is provided in a recessed portion of the front legs. The chairs can thus be stacked with front legs directly abutting.

In an embodiment the rotatable plate is provided with a first set of holes for engagement with the engagement arm when the rotatable plate is in the first or second position, and a second set of holes for engagement with the engagement arm when the rotatable plate is in the third position. Preferably both sets comprise holes spaced symmetrically around the axis of rotation of the seat part and rotatable plate. In an embodiment the locking mechanism comprises a slidable pin slidable parallel to and outside of the axis of rotation of the rotatable plate and provided with an engagement arm adapted for locking engagement with the rotatable plate. In this embodiment no further measures have to be taken to ensure that the engagement arm and/or axle are rotationally fixed with respect to the front leg.

In an embodiment the slidable pin and/or engagement arm is pre-tensioned for engaging the rotatable plate, said rotatable plate preferably comprising guidance means for guiding the engagement arm to engagement positions, such as holes, on the rotatable plate. Such guidance means preferably comprise surfaces in the rotational plate sloping towards a point of engagement in the plate. The seat can thus be locked into the first, second or third position more conveniently.

In an embodiment the axles are adapted for substantially supporting a load on the seat part when in the first position, wherein the upper stops and the axles to which the rotatable plates are connected are adapted for substantially supporting a load on the seat part when in the second position. Substantially no force is thus exerted on the locking mechanism. Preferably, the locking mechanism is adapted for locking the seat part in the first or second position while allowing a small degree of mechanical clearance such that, when the seat part is subjected to a load in a normal manner, the load is substantially supported by the axles or by the axles and the upper stops. Additionally, by allowing some clearance in locking the seat part in the first and/or second position, a person sitting on the edge of the seat will be warned by a slightly tilting movement of the seat part. A small degree of clearance preferably comprises a clearance or 3 mm or less, more preferably a clearance or 2 mm or leas, most preferably a clearance of 1 mm or less between the locking means and the rotatable plate.

Alternatively, the locking mechanism may be adapted for supporting a substantial part of the load, increasing the load capacity of the chair and/or removing some of the load from the axles.

According to a second aspect the present invention provides a folding chair with a height adjustable seat part, comprising a frame having front legs and rear legs, wherein the rear legs are hingeably connected to the front legs, and pivotable around an axis outside of the front legs between a folded position wherein the rear legs are substantially parallel to the front legs, and an unfolded position wherein the rear legs are at an angle to the front legs, said seat part having a first seating surface and an opposite second seating surface, which seat part is attached to the frame so as to be rotatable from a first position, in which the first seating surface is in a position of use, to a second position, in which the second seating surface is in a position of use, and vice versa, wherein the folding chair comprises two rotatable plates fixedly connected to opposing sides of the seat part, wherein each plate is connected to an axle extending from or into its proximate rear leg, said axles being located outside of the plane of the seat part and defining an axis of rotation for the seat part, said rotatable plates being provided with a first abutment element and a second abutment element, wherein the front legs are each provided with a lower stop adapted for abutment with the first abutment element when the seat part is in the first position, and an upper stop adapted for abutment with the second abutment element when the seat part is in the second position, wherein the folding chair is provided with a locking mechanism adapted for engaging the rotatable plate, i.e. at least one of the rotatable plates, at a distance from the axles for locking the seat part into the first and second positions. Preferably the locking mechanism is further adapted for locking the seat part into a third position wherein the seat part is substantially flush with the front legs or with the rear legs.

In summary the invention provides a folding chair comprising a height adjustable seat part, front legs, and rear legs foldable with respect to the front legs, wherein the seat part is connected on either side to a rotatable plate and rotatable around axles defining an axis of rotation outside of a plane of the seat part, wherein the rear legs are provided with stops for stopping movement of the seat part when the rear legs are unfolded and the seat part is in a first or second position of use, wherein the folding chair is provided with a locking mechanism adapted for engaging the rotatable plate at a distance from the axles for locking the seat part into the first and second positions .

The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications .

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which:

Figures 1A and IB show an isometric view of a chair according to the present invention with the rear legs in an unfolded and folded position respectively,

figures 2A, 2B and 2C show a longitudinal cross- sectional view of the chair of figure 1A, with the seat part in locked the first position, locked in the second position and locked in the third position respectively,

figures 3A and 3B show a locking mechanism for a chair according to the present invention in more detail,

figures 4A and 4B show an alternative locking mechanism for a chair according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

Figure 1A shows an isometric view of a foldable chair 1 according to the invention. The chair comprises a frame having front legs 21,22 and rear legs 31,32. The front legs 21,22 and rear legs 31,32 are connected to each other through metal plates 41,42 (shown in figure IB) which are rotationally fixed with respect to the front legs 21,22 and pivotably connected to the rear legs 31,32. A substantial part of the metal plate 41,42 is accommodated within the front legs 21,22 and the rear legs 31,32. A backrest 27 extends between an upper side of the front legs 21, 21 and connects these in a rotationally fixed manner. On a lower side the front legs 21,22 are connected to each other through steps 23,24 which extend between the front legs 21,22 and provide structural integrity to the chair as well as a foot rest and/or mounting step for a person using the chair for sitting or as a stepstool. A beam 28 extends between the rear legs 31 and 32, providing further structural integrity to the rear legs 31,32 and keeping these rotationally fixed with respect to each other. The rear legs 31,32 are pivotable with respect to the front legs 21,22 about hinges 35,36 which define an axis R around which the rear legs are pivotable relative to the front legs, said axis R not intersecting the front legs 21,22. Though the front legs 21,22 and rear legs 31,32 are shown here in an unfolded position, in which the rear legs 31,32 are at an angle a to the front legs 21,22, the rear legs can be placed in an folded position in which the rear legs are aligned substantially parallel to the front legs. The chair 1 comprises a seat part 10, with a first seating surface 11 on one side, and a second seating surface 12 on an opposing side. The seat part 10 is rotatable around an axis S, such the seat part can be placed in a first position in which the first seating surface 11 is in a position of use, and in a second position in which the second seating surface 12 is in a position of use. The axis of rotation S of the seat part 10 lies outside of the plane of the seat part 10, such that when the first seating surface 11 is in a position of use a different seating height results than when the second seating surface 12 is in a position of use. Besides lying outside of the plane of the seat part, the axis of rotation S is also outside of the volume bounded by first seating surface 11 and second seating surface 12.

The front legs 21,22 are each provided with a locking mechanism 65,66 on sides of respective front legs 21,22 opposed to the seating part 10. The locking mechanism 65, 66 is adapted for locking the seat part 10 into the first, second and third positions and is shown in greater detail in figures 3A and 3B. To operate the locking mechanism 65, 66, in particular to unlock the seat part 10 from the first, second or third position, both locking mechanisms 65, 66 must be unlocked, preferably using two hands. It is thus prevented that hands get caught between the seat plate 10 and the front legs 21,22 or rear legs 31,32.

Figure IB shows the same chair with the rear legs 31,32 in a folded position and the seating part 10 in a third position wherein the second seating surface 12 is substantially flush with the front legs 21,22. Sides 37,38 of the rear legs 31,32 and of sides 25,26 of the front legs 21,22 facing each other substantially abut. The folded chair 1 is placed in an upright position, with the centre of mass of the chair substantially within the area spanned by the front legs 21,22 and rear legs 31,32 supporting the chair on the ground. Though the steps 23,24 extend somewhat past the front legs 21,22, multiple chairs can be stacked with the front legs 21,22 of one chair abutting rear legs 31,32 of another chair.

Figure 2A schematically shows a longitudinal cross-section of the chair 1 of figure 1A. The seat part 10, which extends between the front legs 21,22 is shown in the first position, with the first seating surface 11 in a position of use. The seat part 10 is connected on opposing sides to metal rotatable plates 51,52, of which only rotatable plate 51 is shown here. The rotatable plate 51 is adapted for rotating about the axis of rotation S defined by axles 53,54, wherein the rotation of the rotatable plates from the first position to the second position or vice versa results in an height adjustment of the seat part 10 with respect to the frame 21,22,31,32. The axles 53,54 extend from their corresponding plates 51,52 into their proximate front legs 21,22. The plate 51 is provided with a first abutment element 55, in this case a recessed portion along the outer edge of the rotatable plate 51, which abuts a lower stop 37 formed by a portion of rear-leg hinge 35 extending through the rear leg 31. Thus, when weight on the seat part 10 is shifted towards the front legs 21,22, clockwise rotation of the seat part 10 is blocked by the lower stop 37. The rotatable plate 51 is further provided with a second abutment element 57 formed by a similarly formed recessed portion in the plate on an opposite side of axle 53. The plate 51 comprises a number of holes 59, 61, 63, for locking engagement with locking mechanism 65. As can be seen, when the locking mechanism 65 engages hole 59, the seat part 10 is locked in the first position. Thus when weight on the seat part 10 is shifted both clockwise and counter clockwise rotation of the seat part 10 is locked.

To prevent accidental folding of the rear legs 31,32 when the seat part 10 is in the first position, the chair 1 is provided with a first blocking mechanism 67,69. The first blocking mechanism comprises a first blocking element 67 in the form of a nib in the rotatable plate 51, said first blocking element 67 extending from a side of the plate facing the rear leg 31, as well as a first protrusion 69 from the rear leg 31 which faces the rotatable plate 51. When the seat part 10 is in the first position, the first protrusion 69 is arranged at a greater distance from the axis of rotation S of the seating part than the first blocking element 67, and placed abutting or nearly abutting said element. In order to fold the rear leg 31 towards the front leg 21, the first protrusion 69 must be free to move closer to the axis of rotation S of the seat part 10. However, when the seat part 10 is in the first position, such movement is blocked. Thus, when the seat part is in the first position, especially when locked therein, folding of the rear legs 31,32 is blocked. Figure 2A shows in greater detail that the most proximate upper corner of the rear leg has a radius, allowing smooth rotation of the rear leg to a folded position when the seat part is 10 not in the first or second position.

Figure 2B shows a longitudinal cross-section of the chair 1 of figure 1A, however with the seat part 10 locked in the second position. Both clockwise and counterclockwise rotation of the seat part 10 is blocked by engagement of the locking mechanism 65 with hole 61 of the rotatable plate 51, while counter clockwise rotation of the seat part is further blocked by upper stop 39 formed by an upward facing portion of rear-leg hinge 35 extending through the rear leg 31. A second blocking mechanism 71,73 prevents folding movement of the rear leg 31 when the seat part 10 is in the second position. The second blocking mechanism comprises a second blocking element 71 on a side of the rotatable plate 51 facing the rear leg 31, and a second protrusion 73 from the rear leg 31, said second protrusion facing the rear leg. For the rear leg to fold, the second protrusion 73 must move towards the seat part 10. Such movement is however blocked by the second blocking element 71 when the seat part 10 is in the second position, thus preventing folding movement of the rear leg 31.

Figure 2C shows a longitudinal cross-section of the chair 1 of figure 1A, with the seat part 10 locked in the third position, in which position the chair may conveniently be stored or transported. The second seating surface 12 of seat part 10 is substantially flush with the front legs 21,22, and the rear legs 31,32 are folded such that they are arranged substantially parallel to the front legs .

Figures 3A and 3B schematically show the locking mechanism 65 in greater detail when viewed from line IIIA of figure 2A. The locking mechanism comprises a slidable pin 80 slidable parallel to and outside of the axis of rotation S of the rotatable plate 51. The distal end of the slidable 80 pin closest to the rotatable plate 51 forms engagement arm 81 adapted for locking engagement with holes in the rotatable plate, thus locking the seat part in the first, second or third position. The pin is pre-tensioned by a spring 83 to engage the rotatable plate. The locking mechanism further comprises a handle 82 hingeably connected to the slidable pin 80 and to the front leg 21. The locking mechanism is shown in a locked position in figure 3A. By turning the handle 82 in direction A the engagement arm 81 of the pin 80 is moved out of hole 59 of the plate which is then free to rotate, as shown in figure 3B.

Figure 4A shows a side view of an alternative locking mechanism 165 for use in a chair according to the invention. Rotatable plate 151 is provided with a first set of holes 159,161 for engagement with the locking mechanism 165 for locking the seat part 10 into the first or second position, and a second set of holes 163,163a for locking the seat part 10 in the third position.

Figure 4B shows view of the alternative locking mechanism from line IV-A in figure 4A. The locking mechanism 165 comprises a housing 184, which is fixed to the front leg 21 by means of screws 190 and which extends from an outer side of the front leg 21 to an inner side thereof. At least partially within the housing 184 a slidable pin 180 is provided in line with the axis of rotation S of the rotatable plate 51. The pin is thus effectively slidable through at least part of a through passage from the outer side of the front leg 21 to the inner side thereof. Near the inside of the front leg the pin is provided with an engagement arm for engaging the rotatable plate. The rotatable plate 51 is rotatable around an axle 53 which is also part of the housing 184. The pin is provided with ribs 185 and the housing 184 is provided with corresponding grooves (not shown) , such that the slidable pin 180 and engagement arm 181 are substantially rotationally fixed with respect to the housing 184. Near the outer side of the front leg 21, the pin 180 is provided with button 182 for manually sliding the pin. The locking mechanism 165 is provided with a spring 183 for pre-tensioning the pin 180 and the arm 181 connected thereto to engage the rotatable plate at tapered holes 59 and 61 for locking the seat part in the first and/or second position. The tapering of the holes 59,61 and ends of the arm 181 help in guiding the ends of the arm 181 towards the holes. When the button 182 is pressed towards the front leg 21, the engagement arm 181 is no longer in contact with the rotatable plate 51 which is then free to rotate .

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the spirit and scope of the present invention .