This invention concerns in general the office chairs with arm rests, and refers in particular to a height regulating device of the arm rests of such chairs.
Office chairs with arm rests whose height can be regulated and fixed according to the requirements of the user in order to make the seating position more comfortable and cosy are already known.
In the same way, various solutions have been put forward to change the position in height of the arm rests of such chairs.
For example, document FR-A-2 275 762, which correspond to the preamble of claim 1, discloses a blocking device for a movable element on a fixed guide element which has a cutaway with rack cutting along one side. The blocking device includes a pushbutton which can move crossways in relation to the guide element and is equipped with a latch suitable to be moved between a block position, where the latch engages the teeth of the guide element, and a release position which enables the movable element to slide on the guide element.
As described, the pushbutton includes a manoeuvring head with two wings separated by a crosspiece which forms the latch and which is integral with a blade spring suitable to maintain the pushbutton in the blocked position. The two wings of the pushbutton are positioned on opposite sides of the guide element inside the movable element.
The pushbutton, made in this way is however very complex and cumbersome and its shape occupies a significant section of the movable element where it requires to be inserted.
According to another construction described in the document US-A-6 299 253, the blocking device between two telescopic elements is made up of a means of stopping associated with a spring, where, however, the stopping means and the spring are distinctive and separate elements.
It is however an object of this invention to provide a device to regulate the height of a chair arm rest which is particularly simple and efficient, made up of a minimum number of components, thus being practical to make and to assemble, besides being economic.
Another object of the invention is to provide a regulating device of height of an arm rest in which a component carries out two functions at the same time: a means of stopping and a spring.
Another object of the invention is to achieve an arm rest for chairs extendible in height housing a simple, functional regulating device which is also limited in size due to the fact that there are few components.
These objects and the consequent advantages are reached, according to the invention, using a regulating device in compliance with claim 1.
The invention, however, will be described below making reference to the indicative but not limitative drawings, in which:
As shown, an arm rest 10 comprises essentially a bottom fixed element 11 to be attached to one side of the seat ― not shown ― and a movable top element 12 connected with the first element and bearing an arm 13. The fixed 11 and movable 12 elements can be tubular and coupled telescopically one to the other, have any shape cross section and be made of any appropriate material.
The regulating device is located between the fixed 11 and movable 12 elements, allowing the latter to move upwards with respect to the former and allowing it to be blocked at different heights.
On one side of the fixed element 11 there is a recess acting as a groove 14, which extends in upwards and has two vertical parallel sides one of which 15 is straight and the other on the opposite side has a rack 16, the teeth off which face the other side. Two horizontal slots 17, transversally facing and opposite the groove 14 in the fixed element 11, have been provided on the same side of the movable element.
This groove 14 houses a means of positioning and blocking 18 driven by a pulling member 19 and working in conjunction and at the same time with the straight side 15 and with the rack 16.
More precisely, the blocking device is made up a flat-shaped part 20 having on one side, one, two or more teeth 21, on the opposite side two flexible v - shaped arms 22 and, in the middle section, a pair of holes 23. The teeth 21 are facing towards, and interact with, the rack 16. The flexible arms 22, integral parts of the flat-shaped part 20, rest against the straight side 15 of the groove 14 so as to push said part 20 towards the rack 16 to engage with the latter. The two pins 24 protruding from the pulling member 19, passing through and sliding into the slots 17 on the side of the movable element 12 of the arm rest , will click under pressure unto the two holes. Therefore, the pulling member 19 and blocking device 18 are locked to the movable element 12 of the arm rest 10 and move with it when moving upwards, but can also move horizontally thanks to the slots 17 placed crosswise to the groove 14 in the fixed element 11 of the arm rest.
As one can appreciate when observing Fig. 2, the blocking device 18 also acts at the same time as a spring. In fact the flexible arms 22 continuously hold the teeth 21 of said blocking device engaged with the rack 16 making sure in this way that the movable element 12 remains locked to the fixed element 11 of the arm rest at the height required each time.
In order to change the height of the arm rest simply oppose the action of the flexible arms 22 using the pulling member 19, in order to disengage the teeth 21 from the blocking device 18 from the rack 16 so as to be able to move the movable element of the arm rest along the fixed element as needed. On releasing the pulling member 19, the blocking device 18, under the pressure from the flexible arms 22, then returns to engage the teeth of the rack holding the arm rest in the new position.