DEVICE FOR ADJUSTING THE RELATIVE ANGULAR POSITION OF TWO MUTUALLY ARTICULATED STRUCTURES, PARTICULARLY FOR CHAIRS, SEATS OR THE LIKE

Abstract: A device for adjusting the relative angular position of two mutually articulated structures comprising a first and a second element (5, 6) respectively connected to said structures, that rotate mutually around the axis of articulation of said structures and that define two chambers between them whose volume varies inversely as a result of the relative rotation of said elements. Said variable-volume chambers are connected together by conduits (3). The chambers and the conduits are filled with a fluid that flows from one chamber to the other through the conduits as a result of the relative rotation of the two elements around their axis of articulation. Valves are provided for interrupting communication through said conduits (3), so as to prevent the passage of fluid from one chamber to the other and consequently lock the two elements in any relative position to which they have been adjusted.

Description: "Device for adjusting the relative angular position of two mutually articulated structures, particularly for chairs, seats or the like" * * * The present invention concerns a device for adjusting the relative angular position of two mutually articulated structures, suitable for particularly advantageous application to the adjustment of a part of a chair or seat, such as for adjusting the height of the seat of an office swivel chair, or for adjusting the slant of the backrest of a reclining motor car seat. Similar applications can be conceived with reference, for instance, to an adjustment of the inclination of the seat of an office chair, or the adjustment of the armrests, or any other type of adjustment of a moving component of the chair. However, although the description that follows refers in particular to preferred forms of implementation in the field of adjusting the height of a chair, it is important to note that this invention is applicable in general terms to any field in which it is necessary to provide for the possibility to lock two mutually articulated components in any relative angular position. In the specific field of adjusting the position of a mobile component of a chair, e.g. to adjust the height and/or inclination of the seat, or the position of the backrest or of the armrests, devices of various kinds are already known and have been in use for some time. The height adjustment of the seat of office chairs is normally achieved by means of cylinders with gas-assisted springs or the like. Various mechanical devices are also used for adjusting the position of the various components of a chair, such as the backrest or the armrests. The problem that lies behind the present invention is that of developing a device that, as already mentioned, is suitable for general application, but is nonetheless particularly suitable for being applied to the field of chairs, seats or the like, that enables any one adjustable component to be locked in any position along its stroke using an extremely simple, efficient and low-cost solution. For the purpose of solving said problem, the object of the present invention is therefore a device for the adjustment of the relative angular position of two mutually articulated structures, characterized by the fact that it includes: a first and a second element respectively connected to said structures, that mutually rotate around the axis of articulation of said structures and that between them define two chambers, the volume of which varies inversely as a result of the relative rotation of said elements; - conduit elements for connecting said variable- volume chambers together, said conduit elements and said chambers being filled with a fluid, so that said fluid flows from one chamber to the other through said conduit elements as a result of the relative rotation of said first and second elements around their axis of articulation, and valve elements for interrupting the communication through said conduits, so as to prevent the passage of fluid from one chamber to the other and thus lock the two elements in any relative position of adjustment . Preferably, the aforementioned valve elements comprise a normally-closed valve and a valve-opening control device, that can be operated to allow for an adjustment of the relative angular position of aforementioned elements. Said control device can be composed, for instance, of a button or a lever with an flexible return mechanism, that is held by the user in the enabling position in order to be able to manually rotate one element with respect to the other around their axis of articulation until he reaches the required position adjustment, then the control device can be released to interrupt the communication between the two variable-volume chambers and thus lock the structure in the new position it has reached. Preferably, the device is provided with flexible means suitable for returning said elements to their original reciprocal end-of-stroke position. In this way, when the device is released the adjustment is made in one direction with the aid of the aforementioned flexible means and in the opposite direction by opposing the action of said flexible means. As already specified above, the device made according to this invention is suitable for general applications, but is nonetheless particularly suitable for being used in chairs, seats or the like. One form of preferred implementation refers to a chair, particularly an office chair, comprising a seat that is adjustable in height, characterized by the fact that said chair includes a base structure and a seat connected to the base by means of an articulated arm with its two ends attached to the seat and to the base structure on parallel horizontal axes, and by the fact that an adjusting device made according to this invention is provided in line with at least one of said axes of articulation. According to a further preferred characteristic, said articulated arm forms part of a parallelogram connection between the above-mentioned base structure and the seat. The seat of the chair is therefore capable of vertical displacement in that it is connected to the base structure by means of the above- mentioned parallelogram connection. Said parallelogram connection comprises two parallel articulated arms, one of which is fitted with a device made according to this invention at one of its articulating ends. When the device is in the locked condition, the whole system is fixed and the seat of the chair is therefore held at a certain height. Releasing the device allows for the orientation of the parallelogram connection and consequently for the adjustment of the height of the seat, which may be locked again once it has reached the required height by interrupting the communication again between the two variable-volume chambers of the device installed at one end of the aforementioned articulated arm. In a different type of implementation, a single articulated arm is fitted with devices made according to this invention at both ends. In this type of implementation, the first variable-volume chamber of the device at one end of the articulated arm is connected to the first variable-volume chamber of the device at the other end of the articulated arm, while the second variable-volume chamber at said second end of the articulated arm is connected to the second chamber at the first end of the articulated arm by means of the previously-mentioned valves. In this type of implementation, therefore, the locking of the system is achieved by interrupting the communication between two respective chambers at opposite ends of the articulated arm. In both the forms of implementation mentioned above, however, a single valve is capable of controlling the locking of the whole system of adjustable seat support of the chair on the base structure . Clearly, this does not rule out the poss ibil i ty, nonetheless , of providing independent adj ustment devices in l ine with the dif f erent art iculat ions of the structure that connects the seat to the base . Besides , it is perf ectly evident that a device made according to this invent ion is also appl icable to the adj ustment of other components of a chair , such as the forward or backward incl inat ion of the seat of the chair , or the slant of the backrest , or the pos it ion of the armrest . It is equally obvious that a device made according to this invention is also simply and immediately applicable to the adjustment of the reclining backrest of a motor car seat or any other adjustable component of a motor car seat . In such an application, a device made according to this invention of fers the advantage of enabling a continuous adjustment on the one hand and, on the other , of having an extremely straightforward, reliable and low-cost construction . Backrest adjusting devices for motor car seats that enable a continuous adjustment are all relatively complicated and costly, and also involve a relatively lengthy adjustment time . The more straightforward adjustment devices for adj usting the backrest of a motor car seat currently available have the drawback, on the other hand, of only enabling the positioning of the backrest in a series of predetermined positions and therefore allow for a stepping type of adjustment . As already mentioned several times , however , a device made according to this invention can be used successfully in any application where it is necessary to provide for the possibility of a continuous adj ustment to the relative position of two mutually articulated components , with an extremely simple , reliable and low- cost solution . Further characteristics and advantages of this invention will emerge from the description provided in the following pages with reference to the enclosed drawings, provided merely by way of example and in no way restricting the scope of the invention, in which: - Figure 1 is a schematic side view of an office chair using one or more devices made according to this invention, - Figures 2, 3 and 4 are views on an exploded scale and cross-sections of a device made according to this invention in three different operating conditions, - Figure 5 is a cross-section of the first type of implementation of the device made according to this invention, with reference to the height adjustment of the seat of an office chair, Figure 6 illustrates the second type of implementation of the device for adjusting the height of the seat of the chair, - Figure 7 illustrates the type of implementation of shown in Figure 6, in a different operating condition, - Figures 8, 9 and 10 are cross-sections through VIII-VIII, IX-IX, and X-X of Figure 6, and - Figure 11 is a layout of the base structure for an office chair, including the device of Figures 6 and 7. Figure 1 schematically illustrates a chair with a seat that retains its horizontal position even when it is adjusted to a different height. In the same Figure 1, a backrest and an armrest with an adjustable positioning option are also illustrated. Note that the connection of the seat to the vertical supporting element of the load-bearing structure is composed of a combination of two hydraulic devices that form the core element of the present invention. In fact, said application enables an optimal positioning of the seat to be obtained at a variable height. Note that the arrangement of the armrest and backrest illustrated in Figure 1 can be adjusted with corresponding independent adjusting actions. However, said movements can also be adjusted in synchronism with the adjustment of the position of the seat. In Figure 1, reference number 8 indicates the base structure of a chair which, in the example illustrated, is manufactured to a well-known design, comprising a central column provided at the bottom with spokes mounted on castors . Reference number 9 indicates the seat of the chair, that is connected to the base structure 8 by means of an articulated arm 30 the ends of which are attached to the seat 9 and to the base structure 8 by means of adjusting devices 4 made according to the present invention. Similar devices are provided in the articulated joint between the backrest 10 and the seat 9 and in the joint between an armrest 11 and the backrest 10. The operating principle behind the device 4 made according to this invention is schematically illustrated in Figures 2, 3 and 4. Said Figures illustrate a cross-section with respect to the axis of articulation of the device. The two mutually articulated elements (e.g. the base structure 8 and the arm 30 connecting the base structure 8 to the seat 9) are connected respectively to a cylindrical body 4, containing a fixed sector 5 and a moving sector 6, which is guided so that it turns inside the cylindrical body 4. Between the opposite faces of the fixed sector 5 and the mobile sector 6, there are two chambers 1 and 2, the volume of which varies inversely with the relative rotation of the two parts of the articulation. Said chambers, indicated respectively by reference numbers 1 and 2, are placed in communication with each other by means of passages cut through the fixed sector 5 and by means of a flexible external conduit 3. Said conduit and the chambers 1 and 2 are filled with a fluid of any kind, e.g. oil. The fluid tightness of each of the two chambers 1 and 2 is ensured by a deformable diaphragm, la and 2a, sealed to the fixed sector 5 and to the mobile sector 6. Figure 2 illustrates the mobile sector 6 in an intermediate position between its two extreme positions. In this condition, the two chambers 1 and 2 have substantially the same volume. Inside the conduit 3 there is a valve 7 with a shutter on which a spring (not shown in the drawings) comes to bear, that tends to keep the shutter in a closed position. In this condition, communication between the two chambers 1 and 2 is interrupted, so the articulation is locked and it is impossible to turn the two parts of the articulation with respect to each other. By acting on the valve 7 to open the connection through the conduit 3, it becomes possible to perform a continuous adjustment of the relative angular position of the two components of the articulation. Figures 2 and 3 illustrate the two extreme positions of the range of adjustment, in each of which one of the two chambers 1 and 2 reaches its minimum volume while the other chamber reaches its maximum volume. Correspondingly, the diaphragms la and 2a are extended or compressed between the opposing surfaces of the sectors 5 and 6. In the case of the example illustrated, the movement of sector 6 is guided by means of a pin/slot coupling 10,11. It is evident from Figures 2-4 that the fixed body 4 and the fixed sector 5 jointly form a first element, defining a cavity with a ring-shaped sector concentric with the axis of articulation of the device. The second element of the articulation, i.e. element 6, therefore constitutes a sort of piston, that has no parts (e.g. sealing elements) in sliding contact with the walls of the cavity in which it moves, however, because the fluid tightness in chambers 1 and 2 is ensured by the diaphragms la and 2a, each of which folds down, wrapping itself around the corresponding end of sector 6 when it is pressed by said mobile sector (see Figures 3 and 4) . In theory, it would be possible to provide for a device 4 of the kind illustrated in Figure 2 for each articulation of the chair illustrated in Figure 1. This would involve a separate action on each of said devices to obtain the adjustment of the chair in the required position, however. Instead, a synchronized movement of two or more adjustment devices can be obtained by exerting action on a single valve. By way of example, Figure 5 shows a first type of implementation of this solution applied to the two articulations at the end of the oscillating arm 30 that connects the chair's supporting structure 8 to the seat 9. In this case, the two adjustment devices 4 basically have exactly the same structure as the one described with reference to Figures 2-4. However, the two variable-volume chambers of each adjustment device 4 do not communicate directly with each other. In fact, chamber 1 of the adjustment device 4 fitted at the bottom end of the arm 30 is connected by means of a conduit 31 to a chamber 101 of the associated adjustment device 104 at the top end of the arm 30, while the second variable-volume chamber 102 of the device 104 is connected to the second chamber 2 of the associated adjustment device 4 at the bottom end of the oscillating arm 30 by means of a conduit 33 inside which the valve 7 is inserted. In Figure 5, said valve is schematically illustrated as including a conical shutter 34 with a spring 35 that returns it to the position for closing the connection through the conduit 33; the shutter can be opened manually by means of a button 36, which counters the action of the spring 35, moving it to a position that opens the connection through the conduit 33. When said connection is open, the oscillating arm 30 is capable of rotating, thus allowing for an adjustment of the height of the seat 9, while the connection existing through the conduits 31 and 33 ensures a synchronous movement of the two articulations of the arm 30, guaranteeing that the seat 9 is maintained in a position parallel to its original state during the height adjustment. The reference number 37 schematically indicates a spring placed between the base structure 8 and the body of the adjustment device 4 for returning the arm 30 to its raised position. As the drawing clearly shows, the body of the adjustment device 4 is rigidly attached to the articulated arm 30, while the sector 6 of the adjustment device 4 is connected to the base structure 8. At the same time, the arm 30 is rigidly attached to the fixed sector 105 of the adjustment device 104, while the mobile sector 106 of the adjustment device 104 is rigidly attached to the seat 9. The reference numbers la, 2a, 101a and 102a respectively indicate the diaphragms associated with the variable-volume chambers of the two adjustment devices 4 and 104. Figures 6-10 illustrate a preferred type of implementation of a system for connecting the seat of the chair to the corresponding supporting structure using a device made according to this invention. Figures 6 and 7 illustrate the system in the two extreme positions corresponding to the minimum height and the maximum height to which the seat of the chair can be adjusted. In this case, the seat 9 of the chair is connected to the base structure 8 by means of an articulated parallelogram system. In the case of the example illustrated, the base structure 8 includes a forked bracket 80, including two separate parallel plates 81 fitted at the bottom with a pin 8a, which is supported in such a manner as to be able to rotate around its axis (to enable the chair to swivel around a vertical axis) on a supporting structure (of any known type) that is not illustrated (Figure 10) . The two plates 81 support two articulating pins 82 and 83 having axes 82a and 83a (Figure 10) to allow for the articulation of an upper arm 84 and of a lower arm 85 shaped substantially in cross-section like two facing letter "C"s. The opposite end of the two arms 84 and 85 are articulated by means of an upper pin 86 on an axis 86a and two lower side pins 87 (defining an axis 91) on two separate parallel plates 88 of a support 89 with a C-shaped cross-section (Figure 9) to which the seat 9 is attached. Between the two plates 88 of the support 89 there is a body, made of aluminium for instance, indicated by the reference number 90, which rotates freely with respect to the upper pin 86 and, together with the lower arm 85, in line with the axis 91 of the pins 87, defines an adjustment device made according to this invention. In fact, as shown in Figures 6 and 7, the front end of the lower arm 85 comprises two walls 85a and 85b, arranged on radial planes with respect to the axis of articulation 91, which face corresponding plane surfaces of the support 9 which are also radial with respect to the axis 91, so as to define the two variable-volume chambers 1 and 2 of the device. Each of said chambers is associated with a corresponding deformable diaphragm la and lb and they are also placed in communication with each other by means of a passage 93 through the aluminium body 90 which can be intercepted by a ball valve 94 which is held in the closed position by a spring 95 and opened by exerting a manual action on the control button 96. It becomes evident from the previous description that, in this type of implementation, the seat of the chair is connected to the base structure by means of a parallelogram connection, while the adjustment device made according to this invention is provided in line with only one of the axes of articulation of said parallelogram connection. In fact, when the adjustment device provided in line with the axis 91 is locked, any relative rotation between the aluminium body 90 and the lower arm 85 in line with the axis of articulation 91 is prevented, which consequently prevents any movement of the entire parallelogram connection structure. The reference number 37 indicates a spring tending to push the seat back upwards, placed between a body 37a connected in an articulated manner in 37b to a flange 37c of the lower arm 85, while the other end is attached to a tie-rod 110 resting on the supporting element 8. The spring 37 tends to make the articulated parallelogram rotate upwards when the button 96 is operated to enable communication between the two variable-volume chambers 1 and 2. In this condition, therefore, the user can move the seat upwards simply by allowing the return force of the spring 37, or he can move the seat downwards by bringing his own weight to bear on the seat, opposing the force of the spring 37. In the above-described type of implementation, therefore, a single adjustment device in line with one of the axes of articulation of the parallelogram connection can be used to lock the entire parallelogram connection in any given condition coming between its two extreme positions. Moreover, communication between the two variable-volume chambers is achieved by means of passages inside the body 90, and thus without the need for external pipes or conduits of any kind. Obviously, an adjustment system of this kind can be used in any field where it is necessary to provide for the possibility to lock an articulated parallelogram system in any given position. It is evident, moreover, that this invention is also applicable, in principle, to a single axis of articulation between two components, according to the arrangement illustrated in figures 2-4. Naturally, the shape and arrangement of the valves that control communication between the variable-volume chambers and the related operating mechanisms may be of any kind. It is obvious, for instance, with reference to Figures 6 and 7, that the valve 94 must be designed to guarantee the prevent any communication between the two variable-volume chambers even when a considerable force tending to displace the articulated parallelogram system is exerted from the outside. As already mentioned above, particularly advantageous applications of this invention can be conceived in the field of motor car seats, for the adjustment of the slant of the reclining backrest for instance. Figure 11 illustrates the base structure 8 for an office chair incorporating the device of Figures 6 and 7 with the arms 84 and 85 hidden by a cover 200. Thanks to the use of a device made according to this invention, the structure 8 can do without the traditional vertical central supporting column. For instance, spokes 201 can be provided, as illustrated, with castors 203 at one end and with their central ends in a raised position and connected directly to the base of the parallelogram adjustment device. Naturally, without prejudice to the principle of this invention, the manufacturing details and the types of implementation may vary considerably with respect to those described and illustrated here by way of example, without this departing from the context of the present invention.

Claims: CLAIMS 1. Device for the adjustment of the relative angular position of two mutually articulated structures comprising : - a first and a second element (5,6; 85,90) connected respectively to said structures, that rotate mutually around the axis of articulation of said structures and that define two chambers between them (1,2), the volume of which varies inversely with the relative rotation of said elements, - conduit elements (3) connecting said variable- volume chambers (1,2) with each other, said conduits (3) and said chambers (1,2) being filled with a fluid so that said fluid can flow from one chamber to the other through said conduits (3) as a result of the relative rotation of said first and second elements (5,6; 85,90) around their axis of articulation, and valve elements (7) for interrupting communication through said conduits (3), so as to prevent the passage of fluid from one chamber to the other and thus lock the two elements in any relative position to which they have been adjusted. 2. Adjustment device made according to claim 1, characterized by the fact that said valve elements (7) are composed of a normally-closed valve (34) and a control device (36) for opening the valve, which can be operated to enable an adjustment of the relative angular position of the aforesaid elements. 3. Adjustment device made according to claim 2, characterized by the fact that the valve includes a shutter (34) moved by a flexible element (35) towards its closed position, and that said control (36) is designed to push the shutter (34) towards is open position, against the force of said flexible element (35) . 4. Adjustment device made according to any one of the previous claims, characterized by the fact that said device is provided with a flexible element (37) designed to return the aforesaid elements to their reciprocal original extreme positions. 5. Adjustment device made according to claim 1, characterized by the fact that each of said variable- volume chambers (1,2) is fitted with seals comprising a deformable diaphragm (la, 2a) that lines the walls of the chamber and is placed between said mutually articulated elements (5,6) . 6. Adjustment device made according to claim 5, characterized by the fact that the first of said mutually articulated elements (5,6) includes a cavity in the shape of a ring sector concentric with the aforementioned axis of articulation, in which the second element is mobile. 7. Adjustment device made according to claim 6, characterized by the fact that said second element has no part inside it in sliding contact with the walls of said ring-shaped cavity, the fluid tightness of said first and said second chambers (1,2) being ensured by their respective deformable diaphragms. 8. Adjustment device made according to claim 1, characterized by the fact that said first and second elements (85,90) are arranged and articulated together in line with an axis of articulation (91) of a parallelogram connection between a fixed body (8) and a mobile body (9) . 9. Adjustment device made according to claim 1, characterized by the fact that one (5) of said first and second elements (5,6) is also articulated with a third element (106) around a second parallel axis of articulation separate from the first axis of articulation between the first and second elements (5,6) , by the fact that, in line with said second axis of articulation said second and third elements (105,106) define a second pair of chambers of inversely variable volume (101,102), and by the fact that the first chamber (1) associated with the first axis of articulation is connected to a first chamber (101) associated with the second axis of articulation and that the second chamber (102) associated with the second axis of articulation is connected to the second chamber (2) associated with the first axis of articulation by means of valves (7) . 10. Chair, seat or the like, characterized by the fact that it includes an adjustment device made according to any one of the previous claims . 11. Chair, particularly an office swivel chair, comprising a seat (9) that is adjustable in height and characterized by the fact that it includes a base structure (8) and a seat (9) connected to said base structure (8) by means of an articulated arm (85) fixed one end to the seat (9) and the other to the base structure (8), on parallel horizontal axes, and by the fact that in line with at least one of said axes of articulation there is an adjustment device made according to any one of the above claims 1-7. 12. Chair made according to claim 11, characterized by the fact that the above-mentioned seat (9) is connected to the above-mentioned base structure (8) by means of a parallelogram connection, and that the above-mentioned articulated arm (85) is one of the two arms (84,85) forming the aforementioned parallelogram connection. 13. Chair made according to claim 12, characterized by the fact that said articulated arm (85) has a front end connected to the seat (9) of the chair defining two flat walls (85a, 85b) arranged radially with respect to the axis of articulation (91) of said arm to the seat (9) , and that a supporting element (90) is rigidly attached to said seat (9) , defining two flat surfaces lying radially with respect to the previously-mentioned axis of articulation (91) that, together with the above-mentioned radial walls (5a, 85b) define the two variable-volume chambers of the adjustment device, said variable-volume chambers being in communication with each other through passages (93) created in the previously-mentioned body (90) rigidly attached to the seat (9) of the chair. 14. Chair according to claim 13, characterized by the fact that said passages (93) are controlled by a normally-closed valve (95) that can be opened by means of a control button (96) associated with the previously-mentioned body (90) attached to the seat (9) • 15. Chair according to claim 11, comprising a base structure (8) including a number of spokes (201) carrying casters (203) at their outer ends and having their inner ends in a raised position and connected directly to the adjustment device.

Inventors: PEDRINI FABIO, PEDRINI, FABIO
Applicants: PEDRINI FABIO, PEDRINI, FABIO
Application year: 2000
Main classification: A47C3
IPC codes: A47C1, A47C3, F15B7