EP3360443B1 - Height adjustable foot rest - Google Patents

Description

Field of the invention

The invention relates to a footrest for a chair, in particular a height-adjustable footrest, a locking device for a footrest according to the invention, and a chair with a footrest according to the invention.

Background of the invention

Chairs with footrests are known in the art. Especially in the school area chairs with footrests are popular, to allow even smaller students a comfortable sitting on an otherwise too high chair. Furthermore, it is known to make the footrest of a chair height adjustable so that different sized people can use one and the same chair.

In chairs with height-adjustable footpegs, with the footrest located between the two front chair legs, the footrest has two locking pins which engage in locking holes provided on the chair legs. The locking pin is provided in each case an actuating unit with which the respective locking pin can be solved, i. can be pulled out of the respective locking hole.

But this has the disadvantage that a simultaneous extraction of the locking pin from the two locking holes can only be done with both hands.

Another disadvantage is that the two-handed release of the locking pin is not guaranteed that they are solved simultaneously, so that under certain circumstances, the already released side of the footrest is moved up or down, while the locking pin on the other side still in the Locking hole is located. This can lead to damage of the still located in the locking hole locking pin or the locking hole itself.

From the US 390477 A a locking device for a height-adjustable Fußrate a chair is known, wherein the locking device comprises two locking bars which engage in recesses of the chair legs. Both locking rods have radially outwardly guided rod extensions, which are fixedly coupled to a rotatable actuating means. By turning the actuator, the locking rods are moved synchronously in the opposite direction.

From the GB 419 159 A a height-adjustable device is known, which is arranged between two mutually parallel guide rods. The height-adjustable device has two locking bars, which can be brought into engagement with the guide rods. The locking bars have radially outwardly guided rod extensions, the ends of which are designed as gear racks. The gear racks engage in a gear designed as actuating means, so that a rotation of the actuating means causes a synchronous movement of the locking rods in the opposite direction.

Object of the invention

Object of the present invention is therefore to provide solutions that allow a one-handed and at the same time safe and easier height adjustment of a footrest of a chair.

Inventive solution

According to the invention this object is achieved with a locking device for locking a footrest on the chair legs of a chair, a footrest for a chair and a chair according to the independent claims. Advantageous embodiments and further developments of the invention are specified in the respective dependent claims.

• eine erste Sperrstange und eine zweite Sperrstange, und
• ein mit den beiden Sperrstangen zusammenwirkendes Stellmittel aufweist, wobei
• das Stellmittel um eine Drehachse drehbar gelagert ist,
• die beiden Sperrstangen koaxial und beabstandet zueinander und jeweils senkrecht zur Drehachse angeordnet sind,
• die beiden Sperrstangen jeweils mit dem Stellmittel gekoppelt sind, und
• ein Drehen des Stellmittels um die Drehachse bewirkt, dass sich die beiden Sperrstangen synchron in entgegengesetzter Richtung bewegen,

wobei die beiden Sperrstangen an ihren der Drehachse zugewandten Enden jeweils einen Stangenfortsatz aufweisen, der bezogen auf die jeweilige Sperrstange zumindest abschnittweise radial nach außen geführt ist, wobei die radial nach außen geführten Abschnitte der Stangenfortsätze an zwei gegenüberliegenden Seiten der Drehachse verlaufen, und wobei die beiden Sperrstangen über die Stangenfortsätze mit dem Stellmittel gekoppelt sind, und wobei

• die Stangenfortsätze an den radial nach außen geführten Abschnitten jeweils ein Langloch aufweisen, wobei das Langloch im Wesentlichen parallel zur Drehachse verläuft und die Längsachse des Langloches im Wesentlichen senkrecht zur Längsachse der Sperrstangen steht, und
• an dem Stellmittel zwei Zapfen angeordnet sind, wobei der erste Zapfen in das Langloch des ersten Stangenfortsatzes und der zweite Zapfen in das Langloch des zweiten Stangenfortsatzes eingreifen, wobei beim Drehen des Stellmittels um die Drehachse die Zapfen in dem jeweiligen Langloch relativ zum Langloch bewegbar sind.

Accordingly, a locking device is provided for locking a footrest on two chair legs of a chair, wherein the locking device is at least

• a first locking bar and a second locking bar, and
• a co-operating with the two locking rods adjusting means, wherein
• the adjusting means is rotatably mounted about an axis of rotation,
• the two locking rods are arranged coaxially and spaced from one another and in each case perpendicular to the axis of rotation,
• the two locking rods are each coupled to the actuating means, and
• a rotation of the actuating means about the axis of rotation causes the two locking rods to move synchronously in the opposite direction,

wherein the two locking rods each have a rod extension at their ends facing the axis of rotation, which is guided at least in sections radially outwardly relative to the respective locking rod, wherein the radially outwardly guided portions of the rod extensions extend on two opposite sides of the axis of rotation, and wherein the two Locking rods are coupled via the rod extensions with the adjusting means, and wherein

• the rod extensions at the radially outwardly guided sections each have a slot, wherein the slot substantially parallel to the axis of rotation and the longitudinal axis of the elongated hole is substantially perpendicular to the longitudinal axis of the locking bars, and
• on the adjusting means two pins are arranged, wherein the first pin engage in the slot of the first rod extension and the second pin in the slot of the second rod extension, wherein the pins in the respective slot are movable relative to the slot during rotation of the actuating means about the axis of rotation.

This makes it possible in an advantageous manner, both locks to solve simultaneously, especially one-handed.

The adjusting means may have an adjusting disc and a handle portion.

The handle portion may in this case be substantially perpendicular to the adjusting disc.

The two pins are preferably arranged on the adjusting disc. The two pins can be an integral part of the adjusting disc, i. the pins are designed in one piece with the adjusting disc. Alternatively, the pins can also be arranged detachably on the adjusting disc.

The two locking rods and / or the two rod extensions can each be assigned a restoring means, preferably a compression spring. The return means is preferably adapted to move the locking rods away from the axis of rotation.

The locking device may comprise a housing or a cover, wherein the rotational axis facing end portions of the locking rods are disposed within the housing or the cover, wherein the housing or the cover has two edge-side openings, from each of which a locking rod is guided to the outside.

The two edge-side openings may be configured as guide openings, which are adapted to largely prevent rotation of the locking rods about the axis of rotation. On outside of the housing arranged guide means for guiding the locking bars can be dispensed with.

In the housing or in the cover, a substantially cylindrical pin may be arranged, which forms the axis of rotation.

Furthermore provided is a footrest for a chair, which has a locking device according to the invention and two locking elements associated slide elements, wherein the slide elements can be arranged in each case on a chair leg of the chair and along the respective chair leg are displaced.

The carriage elements may each have a guide opening or a guide channel, wherein the guide opening or the guide channel extends transversely to the longitudinal axis of the respective carriage element, and wherein in the guide opening or in the guide channel in each case a free end of the locking bars is received and passed through the guide opening or the guide channel ,

The guide opening or the guide channel can be formed in the carriage element so that they can be brought into a coaxial position with a locking hole formed in the chair leg when the carriage element is displaced along the chair leg.

The footrest may comprise a footrest plate arranged above the locking device, wherein the slide elements each have a fastening means for fastening the footrest plate.

Also provided is a chair with at least two chair legs, which are at least partially substantially rectilinear and parallel to each other, and arranged between the two chair legs locking device according to the invention, wherein the two chair legs each have at least one locking hole, in each case a locking rod of the locking device into engagement can be brought.

On an upper side of the locking device, a footrest plate can be attached, which is displaceable along with the locking device along the chair legs.

Finally, provided is a chair with at least two chair legs, which are at least partially substantially rectilinear and parallel to each other, and arranged between the two chair legs invention footrest, wherein the two carriage elements each on a chair leg of the chair are arranged and are displaceable along the chair leg and wherein the two chair legs each have at least one locking hole, in each of which a locking rod of the locking device can be brought into engagement.

Brief description of the figures

Fig. 1

einen erfindungsgemäß Stuhl in einer perspektivischen Ansicht (Abbildung (a)) und in einer Seitenansicht (Abbildung(b));

Fig. 2

eine Schnittansicht (Abbildung (a)) eines unteren Abschnittes eines Stuhlbeines mit einer daran angeordneten Fußraste (linker Abschnitt) und eine alternative Ausgestaltung eines Schlittenelements (Abbildung (b));

Fig. 3

eine erfindungsgemäße Verriegelungseinrichtung in einer Explosionsansicht (Abbildung (a)), in einer perspektivischen Ansicht im entriegelten Zustand (Abbildung (b)) und in einer perspektivischen Ansicht im verriegelten Zustand (Abbildung (c)); und

Fig. 4

eine erfindungsgemäße Fußraste in einer Explosionsansicht (Abbildung (a)) und in einer perspektivischen Ansicht (Abbildung (b)).

Further details and features of the invention will become apparent from the following description taken in conjunction with the drawings. It shows:

Fig. 1

a chair according to the invention in a perspective view (Figure (a)) and in a side view (Figure (b));

Fig. 2

a sectional view (Figure (a)) of a lower portion of a chair leg with a footrest arranged thereon (left section) and an alternative embodiment of a carriage element (Figure (b));

Fig. 3

an inventive locking device in an exploded view (Figure (a)), in a perspective view in the unlocked state (Figure (b)) and in a perspective view in the locked state (Figure (c)); and

Fig. 4

an inventive footrest in an exploded view (Figure (a)) and in a perspective view (Figure (b)).

Detailed description of the invention

Fig. 1 shows in Figure (a) a chair 5 according to the invention in a perspective view and in Figure (b) the chair shown in Figure (a) in a side view.

The chair 5 is designed here as a cantilever chair. However, the invention can be applied or applied to all types of chairs which have at least two chair legs, at least partially rectilinear and parallel.

The in Fig. 1 shown chair 5 has two front chair legs 70, which each had a substantially rectilinear section 73. The two sections 73 also run parallel to each other. The two sections 73 are substantially perpendicular here - but they can also be inclined, provided they are rectilinear and parallel to each other.

Between the two sections 73 of the chair legs 70, the footrest 1 according to the invention is arranged, which is adjustable in height, as illustrated by the double arrow. The footrest 1 itself has here at the two ends of the chair legs 70 zugten each a slide member 50, which are arranged on the chair legs 70 and along the chair legs, in particular in the region of the two sections 73, are displaceable. On the chair legs 70 and the footrest 1 locking means (locking holes on the chair legs and locking means on the footrest) are provided with which the footrest 1 can be locked or determined at certain heights. On the underside of the footrest plate 60, a handle portion 13b of an actuating means of the locking device according to the invention is shown, with which the lock or release can be solved to move the footrest 1 up or down.

It is important that the lock on both chair legs 70 can be solved with one hand with the handle portion 13b and the footrest 1 can then be adjusted with one hand in their height. As a result, we avoided on the one hand, that when moving the footrest 1 still a lock is unsolved, which can lead to damage to the locking device. On the other hand, a height adjustment of the footrest 1 can do much faster and safer.

Fig. 2 shows in figure (a) the in Fig. 1 , Figure (b) shown section AA of a lower portion of a chair leg 70 with an inventive footrest 1, wherein here the footrest 1 is shown only in sections. The footrest 1 is here in a locked state.

The chair leg 70 is designed here as a hollow profile - but it can also be configured as a solid profile. On the side facing the footrest 1, a plurality of (here three) superimposed and mutually spaced locking holes 71 are provided in the chair leg, which here completely traverse the wall of the chair leg 70. Instead of the locking holes 71 and blind holes can be provided, such as when the chair leg 70 is configured as a solid profile. The locking holes 71 and blind holes should in this case run perpendicular to the longitudinal axes LA2 of the two chair legs.

At the lower end portion of the chair leg 70, a stop 72 or end stop is provided, which projects radially on the chair leg and prevents further lowering of the footrest 1.

On the chair leg 70, a carriage member 50 is arranged, which is designed here as a guide bush (see also Fig. 4 ). The carriage member 50 engages around the chair leg completely and is along the chair leg up and down sliding. In one embodiment of the invention, the carriage member 50 but the chair leg but only partially embrace, as in Figure (b) the Fig. 2 shown. In any case, the carriage member 50 is to be designed so that it is not displaceable in the assembled state of the footrest 1 on the chair only in the axial direction (ie along the longitudinal axis LA2 of the chair tube 70) in the radial direction.

On the side facing the footrest 1, the carriage element 50 has a fastening means 52 for fastening the footrest plate 60 to the carriage element 50 on. The fastening means 52 here consists of two radially extending plates, between which an end portion of the footrest plate 60 is brought into engagement.

Below the fastening means 52, a guide hole 51 and a radial guide channel 51 is also provided on the side facing the footrest 1, in which a locking rod 11a of the locking device 10 is received and can be passed into the interior of the socket, so that the end of the locking bar the inner wall of the socket protrudes. The guide hole 51 and the guide channel 51 are preferably designed coaxially with the locking bar.

The slide element 50 or the guide bushing can be designed in two parts, as in FIG Fig. 4 shown.

On the underside of the footrest plate 60, the locking device 10 according to the invention is arranged, which is fastened here from above with a countersunk screw on the footrest plate 60. On the side wall of the housing 40 and the cover 40, the locking bar 11a out and up to the carriage member 50, where it passes through the guide channel 51 of the carriage member 50 and the lowermost locking hole 71. The locking bar 11a is axially movable in both directions, as shown by the double arrow P2.

By operating the handle portion 13b of the adjusting means 13 of the locking device 10, the locking rod 11a is pulled out of the locking hole 71 to release the lock. After releasing the lock, the carriage element 50 and thus the complete footrest 1 can be moved relative to the chair legs 70 upwards or downwards.

Fig. 3 shows in Figure (a) an inventive locking device 10 in an exploded view, in Figure (b) is a perspective view of the locking device 10 in the unlocked state and in Figure (c) is a perspective view of the locking device 10 in the locked state.

The locking device 10 has a first locking bar 11a, a second locking bar 11b and an adjusting means 13, wherein the adjusting means 13 cooperates with the two locking bars 11a, 11b. With the help of the actuating means, the two locking rods can be moved in the axial direction (indicated by the two double arrows P2) to unlock the footrest 1 and to lock the footrest 1 to the chair legs.

The adjusting means 30 is rotatably mounted about a rotation axis DA, wherein the rotation axis is formed here by a substantially cylindrical pin 41, which is arranged in a housing 40 and in a cover 40. The adjusting means 13 itself here essentially consists of an adjusting disk 13a and of a handle portion 13b arranged on the adjusting disk, which is arranged here perpendicularly to the adjusting disk 13a. The handle portion 13b is designed so that it can be easily grasped with one hand in order to make a one-handed release of the lock as easy as possible. Other embodiments of the handle portion 13b are possible.

Approximately in the middle of the adjusting disc 13a, a borehole is provided, through which the pin 41 (which forms the axis of rotation DA) is passed.

The two locking rods 11a, 11b are arranged coaxially and spaced from each other and each perpendicular to the axis of rotation DA. Thus, the first locking bar 11a is disposed on one side of the pin 41 and the second locking bar 11b is disposed on the opposite side of the pin 41, the two locking bars each being substantially perpendicular to the pin. The position of the two locking rods 11a, 11b relative to the pin 41 is chosen here so that the imaginary extension of the longitudinal axis LA1 of the locking rods passes through the axis of rotation DA.

In an alternative embodiment of the invention, the imaginary extension of the longitudinal axis LA1 of the locking rods but also spaced from the axis of rotation DA extend, which ultimately depends on the specific configuration of the two rod extensions and the arrangement of the locking rods relative to the pin 41. The two locking rods can therefore also be arranged slightly offset in front of or behind the axis of rotation, so that the imaginary extension of the longitudinal axis LA1 of the locking rods passes laterally on the axis of rotation DA.

The adjusting means 13 interacts with the two locking rods 11a, 11b such that a movement, ie a rotation of the actuating means 13 about the rotational axis DA causes the two locking rods 11a, 11b to move in opposite directions, the two locking rods 11a, 1b being synchronous to be moved.

If the handle portion 13b, as shown in Figure (b), pivoted outwardly, both locking rods 11a, 11b are drawn axially to the axis of rotation DA, whereby the lock on both chair legs is released simultaneously.

On the other hand, when the handle portion 13b is pivoted inward as shown in Figure (c), both of the lock rods 11a, 11b move axially away from the rotation axis DA, thereby locking the footrest 1 on both chair legs at the same time.

Both blocking rods 11a, 11b here have a first rod extension 12a and a second rod extension 12b on the end or end portion facing the axis of rotation DA. The two rod extensions 12a, 12b are guided at least in sections radially outwardly with respect to the respective locking rod, wherein the first rod extension 12a of the first locking rod 11a is guided in the opposite direction to the outside as that of the second rod extension 12b of the second locking rod 11b. As a result, the two rod extensions 12a, 12b extend, at least in sections, on two opposite sides of the axis of rotation DA or of the pin 41, so that by rotating the adjusting disc 13a about the axis of rotation both locking rods are moved in the opposite direction.

The two rod extensions 12a, 12b are configured here slightly curved. Other embodiments are possible as long as at least a portion of the respective rod extension extends laterally to the axis of rotation.

The rod extensions can be designed in one piece with the respective locking rod. However, a two-part design of the locking rod and rod extension is possible, wherein the rod extension can also be arranged detachably on the locking rod.

The rod extensions 12a, 12b each have a slot 15 on the sections guided past the axis of rotation. The elongated holes 15 are therefore also arranged radially outside the longitudinal axis LA1 of the locking rods, so that a slot on one side and the other slot on the other side of the axis of rotation DA and the pin 41 is located. The two elongated holes 15 are aligned transversely to the longitudinal axis LA1 of the locking bars, i. the respective longitudinal axis LA3 runs largely transversely to the longitudinal axis LA1 of the locking rods.

On the adjusting disc 13a, two pins 14a, 14b are provided, each associated with a slot 15 and engage in the respective slot and are movable relative to the slot in the respective slot. The adjusting disc 13a is thus coupled via the two pins with the locking rods or with the rod extensions.

The pins 14a, 14b may be configured in one piece with the adjusting disk. Alternatively, the two 14a, 14b can be arranged detachably on the adjusting disc 13a. In a still further alternative embodiment, through holes 13a may be provided in the adjusting disc 13, through which pins may be passed from top to bottom through the adjusting disc 13a.

When rotating the adjusting disc 13a about the axis of rotation DA, the two pins 14a, 14b rotate about the axis of rotation DA, as indicated in the figures (b) and (c) by the arrows P3. At the same time, the elongated holes 15 move parallel to the longitudinal axis LA1 of the locking bars (arrow P4) and the pins 14a, 14b engaging in the slots 15 move radially outwards or inwards (depending on the angle of rotation) relative to the slots. the horizontal distance d between the pins 14a, 14b and the longitudinal axis LA1 of the locking bars increases or decreases.

The two locking rods 11a, 11b and the two rod extensions 12a, 12b are each associated with a restoring means 20a, 20b with which the two locking rods are pushed away in the axial direction from the axis of rotation DA or from the pin 41. That With the return means, the two locking rods are pushed outward. The return means are designed here as compression springs 20a, 20b.

To unlock the footrest 1, the handle portion 13b is rotated outwards, so that the two locking rods 11a, 11b against the spring force of the compression springs 20a, 20b are moved towards the pin 41. Upon release of the handle portion cause the two compression springs that the two locking rods are moved back away from the pin 41, so that the locking rods can engage in the locking holes 71 on the chair legs.

Optionally, the return means can be dispensed with. Then, the handle portion must be manually turned back inside to accomplish locking the footrest 1.

The inner end portions of the lock bars, the rod extensions associated with the inner end portions of the lock bars, the return means and the lock washer are disposed in a housing 40 and a cover 40, respectively. By doing Housing 40 or in the cover 40, the pin 41 is formed, which forms the axis of rotation DA.

On two opposite side walls of the housing 40 and the cover 40 openings are provided through which the locking rods are guided to the outside. These openings serve here simultaneously as a first guide opening 42a for the first locking bar 11a and as a second guide opening 42b for the second locking bar 11b. With the guide openings 42a, 42b, the two locking rods are guided axially and it is prevented that the locking bars laterally tilt away or swing away.

At the bottom of the housing 40 and the cover 40, a nut 31 is provided, which is designed here as a sleeve nut 31, and which cooperates with a guided from the top of the locking device 10 by the locking device screw. Advantageously, the screw is passed through a provided in the pin 41 through hole. With the screw 32 and the sleeve nut 31, the locking device 10 can be fixed to a footrest plate 60, as in Fig. 2 shown.

With the help of a spring washer 30, the adjusting means 13 is secured to the pin 41.

In the locking device shown in Figure (b), this is in a locked state in which the two locking rods protrude from the housing 40 by about 111 mm.

In the locking device shown in Figure (c), this is in an unlocked state in which the two locking rods protrude from the housing 40 by about 119 mm.

The length of the two locking rods depends on the distance between the two chair legs, between which the locking device is to be arranged.

The two locking rods may also have a different length. The locking device 10 or the handle portion 13b is then no longer located centrally between the two chair legs.

Fig. 4 a footrest 1 according to the invention, wherein in Figure (a) the footrest in an exploded view and Figure (b) is shown in a perspective view.

At the two end portions of the footrest plate 60, the two guide bushes 50 are attached. The guide bushes 50 are here designed in two parts.

Between the two mounting plates 52, the footrest plate 60 is inserted into the guide bushes and bolted to the guide bushes. The locking device 10 is disposed on the underside of the Fußrastenplatte 60 and secured by a screw 32 and a sleeve nut 31 on the Fußrastenplatte.

When mounting the locking device 10 on the underside of the footrest plate 60, the housing 40 can remain open at the top, so that the housing essentially forms a cover 40.

Reference numerals:

1

Footrest (locking device 10 and carriage element 50)

5

chair

10

locking device

11a

first locking bar

11b

second locking bar

12a

first rod extension of the first locking bar 11a

12b

second rod extension of the second locking bar 11b

13

actuating means

13a

adjusting disk

13b

handle portion

14a

first pin on the adjusting disc 13a, which engages in the slot 15 of the first rod extension 12a

14b

second pin on the adjusting disc 13a, which engages in the slot 15 of the second rod extension 12b

15

Slot (aligned transversely to the longitudinal axis LA1) in the respective rod extension 12a, 12b

20a

first return means, e.g. compression spring

20b

second return means, e.g. compression spring

30

spring washer

31

Nut, e.g. a sleeve nut

32

screw

40

Housing or cover

41

Spigot that forms the axis of rotation DA

42a

first guide opening for the first locking bar 11a

42b

second guide opening for the second locking bar 11b

50

Slide element (guide bush) for arrangement on a chair leg 70 (displaceable along chair leg 70)

51

A guide channel / guide hole in the side wall of the carriage member 50, which extends transversely to the longitudinal axis LA2 of the carriage member 50

52

Attachment means for attaching the footrest plate 60 to the carriage member 50

60

footrest

70

chair leg

71

Locking holes (vertically spaced from each other) in the chair leg 70th

72

Stop (e.g., radially projecting pin) on chair leg 70

73

largely rectilinear and mutually parallel sections of the chair legs

d

horizontal distance between the pins 14a, 14b and the locking bar 11a, 11b and the longitudinal axis LA1

THERE

axis of rotation

LA1

Longitudinal axis of the locking rods 11a, 11b

LA2

Longitudinal axis of the carriage member 50 and the chair leg 70th

LA3

Longitudinal axis of the slot 15

P1

Arrow - direction of movement (linear movement) of the footrest 1

P2

Arrow - direction of movement (linear movement) of the locking bar 11a, 11b

P3

Arrow - direction of movement (rotational movement) of the pin 14a, 14b

P4

Arrow - direction of movement (linear movement) of the oblong holes 15

Claims (15)

1. An interlocking device (10) for interlocking a footrest (1)with two chair legs (70) of a chair (5), said interlocking device having at least

   - a first locking rod (11a) and a second locking rod (11b), and

   - an adjusting means (13) interacting with the two locking rods (11a; 11b),

   wherein

   - said adjusting means (13) being mounted to rotate about an axis of rotation (DA),

   - the two locking rods (11a; 11b) being disposed coaxially with respect to each other and spaced apart from each other and each being arranged perpendicularly with respect to said axis of rotation (DA),

   - the two locking rods (11a; 11b) being each coupled to the adjusting means (13), and

   - rotation of the adjusting means (13) about the axis of rotation (DA) causing the two locking rods (11a; 11b) to synchronously move in opposite directions,

   said two locking rods (11a; 11b) having each a rod extension (12a; 12b) which is designed so as to extend at least section-wise radially outwardly from the respective locking rod, the sections of the rod extensions (12a; 12b) designed to extend radially outwardly running on two opposite sides of the axis of rotation (DA) and the two locking rods (11a; 11b) being coupled to the adjusting means (13) via said rod extensions (12a; 12b),
   characterised in that

   - the rod extensions (12a; 12b) have each an elongated hole (15) formed on the radially outwardly extending sections, said elongated hole being essentially parallel to the axis of rotation (DA) and the longitudinal axis (LA3) of the elongated hole being essentially perpendicular to the longitudinal axis (LA1) of the locking rods (11a; 11b), and

   - the adjusting means (13) has two pins (14a; 14b) arranged thereon, the first pin (14a) engaging with the elongated hole of the first rod extension (12a) and the second pin (14b) engaging with the elongated hole of the second rod extension (12b), the pins being movable within their respective elongated hole relative to said elongated hole as the adjusting means (13) is turned about the axis of rotation (DA).
2. The interlocking device as claimed in any of the preceding claims, wherein the adjusting means (13) has an adjustment disc (13a) and a handle portion (13b).
3. The interlocking device as claimed in the preceding claim, wherein the handle portion (13b) is essentially perpendicular to the adjustment disc (13a).
4. The interlocking device as claimed in any of the two preceding claims, wherein the two pins (14a; 14b) are disposed on the adjustment disc (13a).
5. The interlocking device as claimed in any of the preceding claims, wherein the two locking rods (11a, 11b) and/or the two rod extensions (12a; 12b) have each a restoring means (20a; 20b), preferably a compression spring, associated therewith which is adapted to move the locking rods (11a; 11b) outwardly and away from the axis of rotation (DA).
6. The interlocking device as claimed in any of the preceding claims, wherein said device has a housing or cover (40), the end portions of the cover locking rods (11a; 11b) turned towards the axis of rotation (DA) being disposed within the housing or cover (40), said housing or cover (40) having two openings (42a; 42b) formed on its edge and through each of which one locking rod (11a; 11b) passes to the outside, respectively.
7. The interlocking device as claimed in the preceding claim, wherein the two openings (42a; 42b) formed on the edge are realised as guide openings which are adapted to substantially prevent the locking rods (11a; 11b) from rotating about the axis of rotation (DA).
8. The interlocking device as claimed in any of the two preceding claims, wherein the housing or cover (40) has a substantially cylindrical pin (41) arranged therein which forms the axis of rotation (DA).
9. A footrest (1) for a chair (5), having an interlocking device (10) as claimed in any of the preceding claims and two sliding elements (50) associated with said interlocking device, said sliding elements being arrangeable each on a chair leg (70) of the chair and capable of sliding along its respective chair leg.
10. The footrest as claimed in the preceding claim, wherein the sliding elements (50) have each a guide opening or guide channel (51), said guide opening or guide channel (51) running transversely to the longitudinal axis (LA2) of the respective sliding element (50), and one free end of the locking rods (11a; 11b) being respectively accommodated in the guide opening or guide channel (51) and designed to pass through said guide opening or guide channel (51).
11. The footrest as claimed in the preceding claim, wherein the guide opening or guide channel (51) is formed within the sliding element (50) in such a manner that it can be brought into a position coaxial with a locking hole (71) formed in the chair leg as the sliding element is displaced along said chair leg (70).
12. The footrest as claimed in any of the preceding claims 9 to 11, wherein the latter has a foot-resting plate (60) disposed above the interlocking device (10) and wherein the sliding elements (50) have each a fastening means (52) for fastening the footrest (60).
13. A chair (5) having at least two chair legs (70) running at least sectionwise in a rectilinear manner and parallel to each other, and having an interlocking device (10) arranged between the two chair legs as claimed in any one of claims 1 to 8, wherein the two chair legs (70) have each at least one locking hole (71) with which a locking rod (11a; 11b) of the interlocking device may be engaged.
14. The chair as claimed in the preceding claim, wherein a foot-resting plate (60) is fastened on an upper side of the interlocking device (10) and can be displaced along the chair legs (70) in conjunction with the interlocking device (10).
15. A chair (5) having at least two chair legs (70) running at least sectionwise in a rectilinear manner and parallel to each other, and having a footrest (1) arranged between the two chair legs as claimed in any one of claims 9 to 12, wherein the two sliding elements (50) are disposed each on one chair leg of the chair and can be displaced along said chair leg, and wherein the two chair legs (70) have each at least one locking hole (71) with which a locking rod (11a; 11b) of the interlocking device may be engaged.

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