Chair with variable inclination of the seat and backrest

Claim 2

A chair, comprising: a bearing block; a seat supported on the bearing block for pivotal movement about a horizontal pivot axis located in a front region of the seat, the seat having a variable inclination defined by a pivot position of the seat relative to the bearing block; a backrest having a variable inclination corresponding to the variable inclination of the seat and pivotable upon a pivotal movement of the seat to a greater degree than the seat; a pair of spaced rocking levers for pivoting the backrest upon the pivotal movement of the seat and having, respectively, first ends for supporting the backrest on the bearing block and second ends pivotally supported on the bearing block for pivotal movement about a common axis located in a variable position relative to the pivot axis of the seat, the rocking levers being pivotally connected to the seat at a location spaced from a rear end of the seat; a return spring located between the bearing block and sections of the rocking levers extending between the second ends thereof and the location, at which the rocking levers are connected to the seat, for automatically returning the seat and the backrest from a working position to a neutral position upon removal of weight applied to the seat by acting on the rocking lever sections; and means for changing in the neutral position of the seat in which no weight is applied to the seat, a position of the return spring relative to the horizontal pivot axis of the seat for changing a returning torque applied by the return spring to the seat.

Claim 3

A chair according to claim 1, wherein the position changing means comprises a longitudinal guide opening, which is formed in the sections of the rocking levers extending between the second ends thereof and the location, at which the rocking levers are connected to the seat, and wherein the return spring has one end thereof secured to the bearing block and another end thereof located in the guide opening for displacement therealong.

Claim 4

A chair according to claim 1, further comprising means for limiting a return movement of the rocking levers so that the rocking levers would not contact a bottom side of the seat.

Claim 5

A chair, comprising: a bearing block; a seat supported on the bearing block for pivotal movement about a horizontal pivot axis located in a front region of the seat, the seat having a variable inclination defined by a pivot position of the seat relative to the bearing block; a backrest having a variable inclination corresponding to the variable inclination of the seat and pivotable upon a pivotal movement of the seat to a greater degree than the seat; a pair of spaced rocking levers for pivoting the backrest upon the pivotal movement of the seat and having, respectively, first ends for supporting the backrest on the bearing block and second ends pivotally supported on the bearing block for pivotal movement about a common axis located in a predetermined position relative to the pivot axis of the seat, the rocking levers being pivotally connected to the seat at a location spaced from a rear end of the seat; a return spring located between the bearing block and sections of the rocking levers extending between the second ends thereof and the location, at which the rocking levers are connected to the seat, for automatically returning the seat and the backrest from a neutral position to a working position upon removal of weight applied to the seat by acting on the rocking lever sections; means for changing a position of the return spring relative to the common axis for changing a returning torque applied by the return spring to the seat; and means for limiting a return movement of the rocking levers so that the rocking levers would not contact a bottom side of the seat; wherein the chair comprises linkage means for pivotally connecting the rocking levers with the seat, and wherein the limiting means comprises an elongate guide hole formed in a bottom of the linkage means and a pin secured to the bearing block and extending into the guide hole.

Claim 6

A chair, comprising: a bearing block; a seat supported on the bearing block for pivotal movement about a horizontal pivot axis located in a front region of the seat, the seat having a variable inclination defined by a pivot position of the seat relative to the bearing block; a backrest having a variable inclination corresponding to the variable inclination of the seat and pivotable upon a pivotal movement of the seat to a greater degree than the seat; a pair of spaced rocking levers for pivoting the backrest upon the pivotal movement of the seat and having, respectively, first ends for supporting the backrest on the bearing block and second ends pivotally supported on the bearing block for pivotal movement about a common axis located in a predetermined position relative to the pivot axis of the seat, the rocking levers being pivotally connected to the seat at a location spaced from a rear end of the seat; a return spring located between the bearing block and sections of the rocking levers extending between the second ends thereof and the location, at which the rocking levers are connected to the seat, for automatically returning the seat and the backrest from a neutral position to a working position upon removal of weight applied to the seat by acting on the rocking lever sections; means for changing a position of the return spring relative to the common axis for changing a returning torque applied by the return spring to the seat; and means for limiting a return movement of the rocking levers so that the rocking levers would not contact a bottom side of the seat; wherein the chair comprises linkage means for pivotally connecting the rocking levers with the seat, and wherein the limiting means comprises an elongate guide hole formed in a bottom of the linkage means and a pin secured to the bearing block and extending into the guide hole.