HEIGHT-ADJUSTABLE STOOL

Description

[0001] The invention relates to a height-adjustable stool according to the preamble of claim 1.

[0002] Such stools are known, for example, from US Pat. No. 2,780,277 A. They are primarily used in offices and are intended to facilitate back-friendly sitting at a desk. Stools of the type mentioned above are known that have a gas spring to adjust their height to the user's height, allowing the length of the connecting part between the base and the seat to be varied. However, this height adjustment is limited to a few centimeters, so adjusting the height of the stool is generally not sufficient for sitting at a height-adjustable desk. Height-adjustable stools are also known whose height can be adjusted within a significantly larger range.In these stools, the inner tube, which is slidably guided in the outer tube, is provided with circumferential grooves at constant intervals, into which a locking element mounted on the outer tube can engage. The locking element is axially movable between a locking position and a release position. The locking element has an inwardly projecting, circumferential rib which engages in the corresponding groove of the inner tube in the locking position and which disengages from the groove when the locking element is moved against a restoring force into the release position. The latter stools, however, have the disadvantage that, if operated incorrectly, there is a risk that the user will suddenly and deliberately slide unbraked from the highest sitting position to the lowest sitting position if the locking mechanism is accidentally released. Other height-adjustable stools are known, for example, from US 3,952,987 A and DE 873 609 C.

[0003] It is therefore an object of the invention to further develop a stool of the type mentioned at the outset in such a way that its height adjustment can be handled more safely.

[0004] This object is achieved according to the invention by a height-adjustable stool having the features of claim 1. Advantageous developments of the invention are the subject of the dependent claims.

[0005] The invention is based on the idea that the locking mechanism is difficult to release when a person sits on the seat and places a significant portion of their weight on it. The more the seat is pressed downward toward the foot, the more the inner tube, with the edge of the opening into which the hook engages, exerts pressure on the hook, inhibiting its movement out of the opening. Releasing the locking mechanism then requires considerable force, which is rarely applied unintentionally.

[0006] It is preferred that the hook has a locking surface facing away from the second lever arm, which, when the hook engages in one of the engagement openings, is inclined radially inwards in a direction away from the end of the inner tube protruding from the outer tube. In the preferred embodiment, according to which the inner tube is connected to the seat part and the outer tube to the foot, this means that the locking surface is inclined radially inwards and downwards. In this embodiment, not only does the frictional force acting between the edge of the engagement opening and the hook prevent the locking from being released, but the locking surface must also be moved upwards a short distance against the weight of the person sitting on the seat acting on it via the inner edge of the engagement opening in question.

[0007] The hook advantageously has a ramp facing away from the locking surface. When the hook engages one of the engagement openings, this ramp is preferably inclined to the horizontal at a greater angle than the locking surface. This feature allows the stool's height to be increased by pulling the inner tube out of the outer tube without necessarily having to release the locking mechanism by operating the second lever arm. If a user stands on the base of the stool and pulls upwards on the seat, the force exerted by the edge of the respective engagement opening on the ramp may be sufficient to release the locking mechanism.

[0008] The locking mechanism advantageously comprises an additional locking lever of identical construction to the locking lever, and the inner tube comprises additional engagement openings that correspond in number and arrangement to the engagement openings. This measure reinforces the locking action and further minimizes the risk of accidentally actuating the locking mechanism to release the locking, since both locking levers must be actuated for this purpose. It is preferred that the locking lever and the additional locking lever, on the one hand, and the engagement openings and the additional engagement openings, on the other hand, are diametrically opposite each other in pairs.Furthermore, it is preferred that the locking lever and the further locking lever are pivotable independently of one another about their respective pivot axes, i.e. that they are not coupled in their movement, so that the release of the locking by one of the two locking levers does not cause the release of the locking by the other locking lever.

[0009] The second lever arm of the locking lever and, if applicable, of the further locking lever is expediently longer than the first lever arm. A user must then perform a relatively large pivoting movement of the second lever arm in order to move the hook out of the engagement opening, thus further reducing the risk of unintentional incorrect operation. Furthermore, the invention provides that the inner tube and the outer tube each have a circular cross-section. In order to prevent undesired twisting of the inner tube within the outer tube, which would cause the engagement openings to be twisted out of the effective range of the hook, a positioning element protrudes radially from the inner tube and is slidably received in a groove running in the axial direction on the inside of the outer tube. The groove can also end at an upper and a lower stop surface for the positioning element, so that the latter has only limited displacement.This measure prevents the inner tube from being pulled out of the outer tube accidentally.

[0010] According to an advantageous development, the inner tube is connected to a sleeve, which rests against the inside of the outer tube, forming a frictional connection. Due to the frictional connection, the sleeve acts as a type of brake, preventing the foot from falling uncontrollably when the seat part is lifted and the locking mechanism is released. The frictional connection counteracts such an uncontrolled fall with a frictional force, which can, however, be easily overcome by pressing down the foot and pulling up the seat part. In particular, it can be provided that the positioning element is a pin arranged on the sleeve.

[0011] The sleeve expediently has a shoulder protruding from the end of the inner tube received in the outer tube and resting against the inside of the outer tube. It is preferred that the inner tube be held at a distance from the inside of the outer tube over its entire length by means of the shoulder and a guide element arranged at the end of the outer tube facing the seat part. When the inner tube is moved relative to the outer tube, the two tubes then do not rub against each other. The sleeve is expediently made of plastic, at least in the area of ​​the shoulder.

[0012] The frictional connection is advantageously achieved by means of at least one friction element provided on the sleeve, which is pressed against the inside of the outer tube by an elastic force. The friction element can be a ring made of an elastomer material that surrounds the sleeve. However, it is also possible for the sleeve to contain two diametrically opposed friction elements, each of which passes through a hole in the inner tube and is pressed away from each other by a spring toward the inside of the outer tube.

[0013] The invention will be explained in more detail below with reference to an embodiment shown schematically in the drawing. Fig. 1 a height-adjustable stool in side view in section; Fig. 2a, 2b Detailed views A and B from Fig. 1 ; Fig. 3 the stool according to Fig. 1 in cutaway perspective view and Fig. 4a, 4b Detailed views A and B from Fig. 3 .

[0014] The stool 10 shown in the drawing has a base 12 with a convexly curved base surface 14 on the underside for placement on a floor, and a seat part 16 with an upper seat surface 18. The base 12 and the seat part 16 are connected to one another by means of a connecting part 20, which has an outer tube 22 firmly connected to the base 12 and an inner tube 24 firmly connected to the seat part 16, which is received in the inner tube 22 for longitudinal movement and protrudes from the outer tube 22 with an upper end 26. The outer tube 22 and the inner tube 24 each have a circular cross-section. The seat part 16 can be arranged at different heights relative to the base 12 by displacing the inner tube 24 relative to the outer tube 22, by locking the inner tube 24 relative to the outer tube 22 in a number of different positions by means of a locking mechanism 28.

[0015] The locking mechanism 28 has a locking lever 30a and a further locking lever 30b diametrically opposite the locking lever 30a, each of which is pivotally mounted on the outer tube 22 about a pivot axis 32. The locking lever 30a and the further locking lever 30b are identical in construction and each have a first lever arm 34 extending upwards from the pivot axis 32 and having a hook 38 at its free end 36, as well as a second lever arm 40 extending downwards from the pivot axis 32 and protruding obliquely from the outer tube 22, which second lever arm 40 is longer than the first lever arm 34. Pivoting the second lever arm 40 radially inward, combined with pivoting the first lever arm 34 outward, occurs against the force of a return spring (not shown in detail in the drawing) which is supported on the outer tube 22.The inner tube 24 has a series of equally spaced engagement openings 42a extending in the axial direction, into which the hook 38 of the locking lever 30a engages to fix the inner tube 24 to the outer tube 22. Diametrically opposite each of the engagement openings 42a is a further engagement opening 42b, into which the hook 38 of the further locking lever 30b engages. When the hooks 38 each engage one of the engagement openings 42a and one of the further engagement openings 42b, the first lever arm 34 of the locking lever 30a and of the further locking lever 30b each protrudes obliquely inward, while the second lever arm 40 protrudes obliquely outward from the outer tube 22. The hooks 38 each have a locking surface 44 on their upper side facing away from the respective pivot axis 32, which is inclined radially inwards and downwards when engaging in one of the engagement openings 42a or one of the further engagement openings 42b.Facing away from the locking surface 44, the hooks 38 each have a run-up slope 46 which, when the respective hook 38 engages in one of the engagement openings 42a or in one of the further engagement openings 42b, is inclined radially inwards and upwards, wherein its angle of inclination relative to the horizontal is then greater than the angle of inclination of the opposite locking surface 44 relative to the horizontal.

[0016] At the lower end 48 of the inner tube 24 located in the outer tube 22, there is a sleeve 50 which is received in the inner tube 24 over most of its length. While the outer tube 22 and the inner tube 24 are made of metal, the sleeve 50 has a base body made of plastic. It has a shoulder 52 protruding from the lower end 48 of the inner tube 24, which also has a circular cross-section, but whose diameter is larger than the outer diameter of the inner tube 24 and, minus a small amount of play, corresponds to the inner diameter of the outer tube 22, so that it rests against the inner side 54 of the outer tube. Together with a guide element 56 arranged at the upper end of the outer tube 22 facing away from the base 12 and resting against the inner tube 24, the inner tube 24 is always held at a distance from the inner side 54 of the outer tube 22.The sleeve 50 also has two pin-shaped friction elements 58 that extend through diametrically opposed holes 60 in the inner tube 24 and bear against the inner side 54 of the outer tube 22. A compression spring 62, designed as a helical spring, is arranged between the two friction elements 58 and presses the friction elements 58 away from each other against the inner side 54 of the outer tube 22 to create a frictional connection. In addition, a pin-shaped positioning element 64 projects radially from the sleeve 50 and engages in a groove in the outer tube 22 (not shown in detail in the drawing), so that the inner tube 24 is held in the outer tube 22 in a rotationally fixed manner. The groove is delimited at the top and bottom by a stop surface each, so that the positioning element 64 can only be moved to a limited extent between the stop surfaces and prevents the inner tube 24 from being completely pulled out of the outer tube 22.

[0017] In summary, the following can be stated: The invention relates to a height-adjustable stool 10 with a base 12 for placing on a floor, with a seat part 16 having an upper seat surface 18 and with a connecting part 20 connecting the base 12 and the seat part 16, wherein the connecting part 20 has an outer tube 22 and an inner tube 24 slidably received in the outer tube 22, wherein either the outer tube 22 is fixedly connected to the base 12 and the inner tube 24 is fixedly connected to the seat part 16 or the outer tube 22 is fixedly connected to the seat part 16 and the inner tube 24 is fixedly connected to the base 12, and with a locking mechanism 28 for releasably locking the inner tube 24 on the outer tube 22 in a plurality of positions defining different distances of the seat part 16 from the base 12.According to the invention, the locking mechanism 28 has a two-armed locking lever 30a which is pivotally connected to the outer tube 22 about a pivot axis 32 and which has a hook 38 at the free end 36 of its first lever arm 34 and whose second lever arm 40 projects obliquely outwards from the pivot axis 32 and can be pivoted radially inwards against the force of a return spring, and that the inner tube 24 has a number of engagement openings 42a arranged at a distance from one another in a row for the hook 38. Additionally or alternatively, the invention provides that the inner tube 24 is connected to a sleeve 50 which bears against the inner side 54 of the outer tube 22 to form a frictional connection.

Claims

1. Height-adjustable stool having a foot (12) for placing on a floor, having a seat part (16) having an upper seating surface (18), and having a connecting part (20) which connects the foot (12) to the seat part (16), wherein the connecting part (20) has an outer tube (22) and an inner tube (24) which is received so as to be displaceable in the outer tube (22), one of said tubes being fixedly connected to the foot (12) and the other being fixedly connected to the seat part (16), and having a blocking mechanism (28) for releasably blocking the inner tube (24) on the outer tube (22) in a plurality of positions that define different spacings of the seat part (16) from the foot (12), wherein the blocking mechanism (28) has a two-armed blocking lever (30a) which is pivotably articulated on the outer tube (22) so as to be pivotable about a pivot axis (32), and on the free end (36) of its first lever arm (34) has a hook (38), and the second lever arm (40) thereof, proceeding from the pivot axis (32), projects obliquely outwards and is pivotable radially inwards counter to the force of a restoring spring, and wherein the inner tube (24) has a number of engagement openings (42a) for the hook (38) that are disposed so as to be mutually spaced apart in a row, wherein the inner tube (24) and the outer tube (22) each have a circular cross section, and characterized in that a positioning element (64) projects radially from the inner tube (24), said positioning element (64) being received so as to be displaceable in a channel that runs in the axial direction on the inside (54) of the outer tube (22).

2. Stool according to Claim 1, characterized in that the hook (38) has a blocking face (44) which faces away from the second lever arm (40) and during an engagement of the hook (38) in one of the engagement openings (42a) is inclined, in an oblique radially inward manner, in a direction away from the end (26) of the inner tube (22) that protrudes from the outer tube (22).

3. Stool according to Claim 2, characterized in that the hook (38) has a ramp (46) which faces away from the blocking face (44) and in relation to the horizontal is preferably inclined by a larger angle than the blocking face (44) when the hook (38) engages in one of the engagement openings (42a).

4. Stool according to one of the preceding claims, characterized in that the blocking mechanism (28) has a further blocking lever (30b) which is identical to the blocking lever (30a) in terms of construction, and in that the inner tube (24) has further engagement openings (42b) for the hook (38) of the further blocking lever (30b) that in terms of number and arrangement correspond to the engagement openings (42a), wherein the blocking lever (30a) and the further blocking lever (32b), on the one hand, and the engagement openings (42a) and the further engagement openings (42b), on the other hand, are preferably diametrically opposite in pairs, and wherein the blocking lever (30a) and the further blocking lever (30b) are in particular pivotable about their respective pivot axis (32) in a mutually independent manner.

5. Stool according to one of the preceding claims, characterized in that the second lever arm (40) of the blocking lever (30a), and optionally of the further blocking lever (30b), is longer than the first lever arm (34).

6. Stool according to one of the preceding claims, characterized in that the channel terminates at an upper and a lower detent face for the positioning element (64).

7. Stool according to one of the preceding claims, characterized in that the inner tube (24) is connected to a sleeve (50) which, while forming a friction fit, rests on the inside (54) of the outer tube (22).

8. Stool according to Claim 7, characterized in that the positioning element (64) is a pin disposed on the sleeve (50).

9. Stool according to one of Claims 7 or 8, characterized in that the sleeve (50) has a shoulder (52) which protrudes from that end (48) of the inner tube (24) that is received in the outer tube (22) and rests on the inside (54) of the outer tube (22).

10. Stool according to Claim 9, characterized in that the inner tube (24) by means of the shoulder (52) and of a guiding element (56) which is disposed on that end of the outer tube (22) that faces the seat part (16) is held at a spacing from the inside (54) of the outer tube (22) over the entire length of said inner tube (24).

11. Stool according to one of Claims 7 to 10, characterized in that the sleeve (50) has at least one friction element (58) which by means of an elastic force is pressed against the inside (54) of the outer tube (22).

12. Stool according to Claim 11, characterized in that the friction element (58) is a ring, made of an elastomer material, which encircles the sleeve (50).

13. Stool according to Claim 11, characterized in that the sleeve (50) has two friction elements (58) which are mutually diametrically opposite and engage in each case through a hole (60) in the inner tube (24), and by means of a spring (62) are pressed away from one another towards the inside (54) of the outer tube (22).