APPARATUS FOR ADJUSTING AND LOCKING THE BACK REST IN A CHAIR

Abstract: Apparatus for adjusting and locking the back rest of a chair, wherein the seat and the back rest are pivotally engaged to each other and the back rest is pivotally engaged to the chair frame or equivalent, so that the seat rests against the chair frame and the inclination of the back rest can be adjusted into a desired position by aid of the apparatus of the invention. The apparatus comprises a control shaft (1), a lock device (2) and a locking member (3). The control shaft (1) of the apparatus is an elongate member which at one end (1a) is attached to the seat (9). The other end (1b) of the control shaft (1) remains free. The lock device (2) is provided with an aperture (5), whereinto the control shaft (1) is fitted. The lock device (2) is attached to the chair frame. The locking member (3) is coupled to the lock device (2) by aid of threadings. By revolving the locking member (3) into one direction by aid of a lever (4), the control shaft (1) is released to move freely along the aperture (5) of the lock device, and simultaneously there are also released the seat (9) and the back rest, which can both be adjusted into a desired position, whereafter by revolving the locking member (3) by aid of the lever (4) into the opposite direction, the control shaft (1) is again locked into the aperture (5) of the lock device, and the seat (9) and the back rest are accordingly locked into place.

Description: APPARATUS FOR ADJUSTING AND LOCKING THE BACK REST IN A CHAIR The present invention relates to an apparatus for locking and * adjusting the back rest in a chair, the seat and back rest - ■ * whereof are pivotally attached to each other and the back rest * is pivotally attached to the frame or equivalent of the chair, so that the seat rests supported by the chair frame and the inclination of the back rest can be adjusted and the back rest can be locked into a desired position by aid of the apparatus of the invention. In the prior art there are known several chairs, particularly rest chairs, where the position of the back rest is adjustable. One such adjustable rest chair is introduced for instance in the Finnish publication of application 20 829, where in between the seat and the back rest there is fitted a spring arrangement and a locking machinery which, by means of the spring arrangement, prevent the back rest from rising up, but allows the back rest to be lowered down against the pressure of the spring arrangement. Such adjusting and locking devices must be attached to the frame of the seat and the back rest before providing upholstery for the chair in question. Consequently, owing to the covering upholstery, the maintenance and repair of the said devices is troublesome. Moreover, these devices are relatively complicated in construction and therefore costly to manufacture. The purpose of the present invention is to achieve a simple and reliable device for adjusting and locking the back rest in a chair. This is achieved by aid of the characteristic novel features of the invention which are presented in the appended patent claims. Among the advantages of the present invention, there are pointed out the following. The apparatus is simple in structure, i.e. it comprises very few separate elements, wherefore it is economical to manufacture. The apparatus can be applied in both upholstered and non-upholstered chairs; it . 2 is installed under the seat where it doesn't catch the eye, and most advantageously on top or outside of the possible upholstery. The installation of the apparatus does not by any means make the upholstery work difficult, because all elements are located outside the upholstery. The height of the seat can be maintained- constant irrespective of the inclination of the back rest, so that the apparatus can be employed in couches, where the separate seats can be adjusted either separately or together. The motional path of the seat in the vertical direction can be chosen by means of changing the shape of the control rail to be installed. The adjusting and locking the back rest of the chair is easily carried out by aid of the lever included in the apparatus, because the said lever is well In hand also when the back rest is nearly flat in the lying position and because the necessary adjusting motion of the lever is comparatively slight. From the point of view of a furniture designer, an important advantage of the apparatus of the invention is that the designer has free hands as regards the design. The apparatus takes up only a small amount of space, it is easily installable to an otherwise ready-made chair, and it can also be used in chair constructions which don't include such elements, for instance arm rests, that are located at the sides. Moreover, the chair can be delivered to the consumer in elements, because the existence of the adjusting and locking apparatus does not make the assembling of the chair considerably more difficult. In the following the invention is explained in more detail with reference to the appended drawings, wherein Figure 1 illustrates a rest chair which is provided with the apparatus of the invention, so that the back rest of the said chair has two adjustable positions: the upright position 1A and the rest position IB; Figure 2 illustrates, in partial side-view elevation, the apparatus of the invention as attached to the rest chair of figure 1; Figure 3A shows the essential parts of the apparatus of the Invention in a broken-up elevation seen from the top, and Figure 3B shows the same essential parts in a broken-up front- view elevation; Figure 4 illustrates the guide to be attached onto the bottom surface of the seat, which guide in figure 4A is arched and in figure 4B is wave-like. The rest chair of figure 1 comprises the seat 9, the back rest 10 and the frame 11. The frame 11 is formed of two elements located on both sides of the seat and the back rest, i.e. of the interconnected leg 13 and arm rest 14, which are attached to each, other by aid of the front support 12. The seat 9 and the back rest 10 are pivotally engaged to each other so that they can be turned with respect to each other. The back rest 10 is at its edges turnably attached to the frame 11 at the attaching point 21, above the pivotal juncture 20 of the seat and the back rest. The seat 9 rests freely on top of the frame 11, in this particular embodiment on top of the front support 12 of the frame, so that it can be moved forward and backward while adjusting the inclination of the back rest. The apparatus for adjusting and locking the back rest is installed in between the frame 11 and the seat 9. The apparatus of the invention for adjusting and locking the back rest comprises, as is seen in figure 2, the control shaft 1, the lock device 2 and the locking member 3. The control shaft 1 is an elongate member, one end la whereof is attached to the seat 9. The other end lb of the control shaft 1 is left free. The lock device 2 of the apparatus is provided with at least one aperture 5, slot or equivalent, whereinto the control shaft 1 is fitted. The lock device 2 is attached to the chair frame, for instance to the front support 12 of the frame, or to a member permanently connected to the frame. The locking member 3 is connected to the lock device 2 so that by means of the locking member 3, the control shaft 1 can be released to move along the aperture 5 of the lock device 2, whereby the seat 9 and the back rest 10 can be released and adjusted to the desired position, whereafter the control shaft 1 can again be locked, by aid of the locking member 3, to the aperture 5 in the lock device so that the seat 9 and the back rest 10 are also locked into place therealong. In short, the locking member 3 is employed for pressing the control shaft 1 into place in the lock device 2 and for releasing the shaft therefrom. Tn cross-section, the control shaft 1 can be for instance round, elliptical or square, or a flat rectangle, and it can be composed of several elements. The length of the shaft is defined according to the structure of the seat so that the control shaft 1 remains in the aperture 5 of the lock device and moves freely along this aperture 5 while the inclination of the back rest is being adjusted within the predetermined limits. The first end la of the control shaft 1 is attached to the seat 9 so that the control shaft is free to move at least in the vertical direction with respect to the seat and thus to conform to the movements of the seat. Accordingly, the control shaft can be attached to the seat pivotally, for example by means of a trunnion coupling 22. The control shaft 1 may be either a straight member, as is illustrated in figures 1 and 2, or an arched member. In some cases a straight control shaft may touch the bottom structures of the seat, which can be avoided when using an arched control shaft. The locking member 3 is coupled to the lock device 2 advantageously by aid of threadings. By winding the locking member into one direction, the control shaft 1 can be released to move along the aperture 5 of the lock device 2, and* by winding the locking member into the opposite direction, the control shaft 1 can again be locked into place in the aperture 5. The lock device 2 can easily be realized so that within the said lock device, there is arranged, at least nearly vertically against the aperture 5, the hole 6 provided with female threadings 7. Into the hole 6 there is fitted the locking member 3 provided with corresponding male threadings 8. The threadings 7, 8 are advantageously comparatively high-pitched, so that by revolving the locking member 3 for half a circle at the most, the control shaft 1 can be locked into the aperture 5 of the lock device 2 or released therefrom. The pitch of the threadings 7, 8 can be for instance between 0,5 - 4 mm, in which case the revolving of the locking member for three quarters of a circle leads to a shift of 0,12 - 1 mm of the locking member with respect to the lock device 2, i.e. to a constriction of the aperture 5 or equivalent. The matching of the control shaft 1 and the aperture 5 of the lock device corresponds to the said shift so that the control shaft 1 is, by aid of the locking member 3, jammed into place in the aperture 5 of the lock device 2. The end of the locking member 3, which end is connected to the lock device 2, can be coarsened or it can be provided with a separate piece whereby the aperture 5 can be effectively constricted, and for instance the friction surface between the control shaft 1 and the aperture 5 can be increased. The aperture 5 of the lock device 2 is conical-so that it is at least in one direction narrower in the middle than on the front and/or back surface of the lock device as is seen in figures 3A and 3B. The conical shape in the longitudinal direction, i.e. on the vertical plane against the seat, secures that the control shaft 1 can easily conform to the movements of the seat 9. If the aperture 5 is conical also in the horizontal direction, i.,e. the aperture 5 and the control shaft 1 are tightly matched only in a relatively narrow area, the apparatus of the invention is easily installed into place in the -chair. In that case it is not necessary to install the control shaft 1 vertically against the lock device 2, but the installation can be carried out within wider limits, for instance at an angle between 5° - 15°. The lock device 2 is advantageously manufactured of one single, uniformly thick piece of metal having a regular shape, such as a rectangle, square or polygon, or a circle, so that in the middle of the said piece, there is cut an aperture 5 for the control shaft 1 (cf. figures 3A and 3B) . Across the piece, advantageously vertically or nearly vertically against the aperture 5 and particularly its narrowest spot, there is drilled the hole 6, which is provided with threadings 7. The lock device 2 is provided with perforations 23 so that it can be attached, for instance by aid of screws, into the chair frame. The lock device 2 can naturally also be manufactured in some other way, for example out of a separate sleeve provided with the aperture 5 and coupled to the housing of the lock device 2. The lock device 2 can be realized so that the housing is formed of a for example sheath-like or U-shaped construction, inside which construction the end of the locking member 3 extends. * On one side of the lock device there is located a hole provided with threadings, and the locking member 3 is fitted into the hole." The end thereof can be provided with a suitable back stop. The control shaft is pressed into the aperture located in between the back stop and the other side of the frame, and respectively released therefrom. In the preferred embodiment of figure 1, the lock device 2 is attached to the front support 12 of the chair frame. In addition to this, the support is provided with the hole 15 wherethrough the shaft 1 can unhindered be brought into the aperture 5 of the lock device 2. The control shaft 1 can be attached, apart from the front edge of the seat 9 of the chair, as in the rest chair of figure 1, also to the center or to some other spot in the seat. ' The location of the chosen spot of engagement depends on the structure of the chair and for instance on the fact to which particular spot in the frame the lock device 2 can be attached. There are several alternatives for attaching both the control shaft 1 and the lock device 2 to the chair. Advantageously the locking member 3 is a straight rod of a desired length, the first end thereof being provided with threadings 8 as is illustrated in figure 3. The locking member 3 can also be provided for instance with the lever 4, which is placed at an angle with respect to the locking member 3 proper. The locking member 3 is revolved by winding the lever 4. The locking member 3 can also be realized so that no threadings are used - neither there nor in the lock device 2. Such a locking member is attached or fitted into the lock device so that neither the distance, nor the position between them changes. At the end of the locking member there is provided a conical member which is revolved along with the locking member, the said conical member being for instance a straight wedge, a cone, a wobbler etc. This is fitted into the aperture 5 of the lock device 2 so that while the locking member is revolved with respect to the lock device, the conical member is also wound or revolved, so that the locking' member is in a way lengthened, thus closing part of the aperture 5 and pressing the control shaft 1 against the other end of the aperture 5, and consequently locking the control shaft into place. Respectively, by revolving the locking member into the opposite direction, the conical member is wound outward and releases the control shaft to move within the aperture 5. It is advantageous to place a counterscrew (not illustrated in the drawings) on the opposite side of the aperture 5 or equivalent opening, i.e. opposite with respect to the locking member 3. By winding this screw, the size of the aperture 5 can be suitably adjusted so that by aid of a slight shift of the locking member, the control shaft 1 is securely locked into place. In between the seat 9 and the frame 11 or equivalent part such as the front support 12, there can be installed a member for diminishing friction, for instance a roller or a slide 16, or a sliding guide 17. One or several slides, which are for instance made of nylon, are attached to suitable spots in the frame, in between the seat and the frame. The sliding guide or guides 17 are attached at the bottom surface of the seat 9, at spots corresponding to the slides 16 or, if slides are not employed, for instance at regular intervals from both edges of the seat 9. In structure the guide 17 is advantageously a relatively narrow, elongate member, which is made of a hard, sliding material, such as steel. The length of the guide 17 is such that the seat 9 and respectively the back rest 10 can be shifted supported by it within the limits of the adjusting range. The guide 17 can be straight in the lengthwise direction as is illustrated in figure 2. On the other hand, the guide 17 can also be wave-like in shape, so that the guide rises from the front edge of the seat towards the rear edge, as is illustrated in figure 4A. Such a rising guide has the advantage that the height of the seat is maintained constant also when the back rest is adjusted at a wide angle or lowered almost flat into the lying position. In that case the rear edge 17a suitably lifts the front edge of the seat 9. The guide 17 can also be wave-like, as is illustrated in figure 4B. By aid of a wave-like guide, the seat position can be adjusted in soft steps. The adjusting and locking apparatus of the invention can be employed for setting limits for the back and forth movements of the seat, and similarly to the adjusting range of the inclination of the back rest. This can be realized in two ways: the stoppers for stopping the movement of the seat 9 can be installed either in connection with the control shaft 1 and/or in connection with the guide 17. In connection with the control shaft 1, the stoppers 18 are separate members, a desired number of which can be placed at the first end la and/or at the second end lb of the control shaft 1. They can be for example annular in shape, as is illustrated in figure 2, but they can also be for instance sleeves, trunnions etc. The adjusting range of the seat is defined on the basis of the free' length of the control shaft 1 left in between the stoppers 18 and/or for instance the juncture 22 of the first end la. Either or both ends of the guide 17 can also be alternatively provided with a limiting member, i.e. a stopper 19. In that case the the back and forth movement of the seat is arrested by means of such a stopper. In the above specification, the invention is mainly explained with reference to a rest chair, but it is clear that it can be applied in other adjustable chairs as well, such as ordinary chairs, armchairs, auditorium chairs, couches, convertible sofas and garden chairs.

Claims: PATENT CLAIMS 1. An apparatus for adjusting and locking the back rest in a chair, wherein the seat and the back rest are pivotally engaged to: each other and the back rest is pivotally engaged to the frame or equivalent structure of the chair, and the said seat (9) rests supported by the chair frame (11) and the inclination of; the said back rest can be adjusted and the back rest can be locked into a desired position by means of the apparatus, c h a ra c t e r i z e d in that the apparatus comprises a eontϊGl sha£t~ ti) f a look άevioe {I) and a locking member (3), the control shaft (1) of the said apparatus being an elongate member which is attached, at one end (la), to the seat (9), the other end (lb) remaining free; that the lock device (2) of the said apparatus is provided with an aperture (5) or similar opening whereinto the control shaft (1) is fitted and the said lock device (2) is attached to the chair frame or to an element permanently^ connected thereto; and that the locking member (3) is connected to the lock device (2) so that by means of the locking member (3), the control shaft (1) can be released to move freely along the aperture (5) of the lock device, wherealong there are also released the seat (9) and the back rest (10), which can be adjusted into a desired position, whereafter the control shaft (1) is again locked, by employing the said locking member (3), into the aperture (5) of the lock device, and accordingly the seat (9) and the back rest *(10) are Locked into place. 2 " The apparatus of claim 1, c h a r a c t e r i z e d in that the locking member (3) is connected to the lock device (2) by aid of threadings (7, 8) so that by revolving the locking member (3) into one direction, the control shaft (1) can be released to move along the aperture (5) of the lock device (2), and that simultaneously there are released both the seat (9) and the back rest (10), which can be adjusted into a desired position, whereafter, by revolving the locking member (3) into the opposite direction, the control shaft (1) can again be locked into the aperture (5) of the lock device and accordingly into place. 3. The apparatus of claim 1 or 2, c h a r a c t e r i z e d in that in the lock device (2), there is provided a hole (6) located at least roughly at right angles against the aperture (5), the said hole (6) being provided with threadings (7), and that into the said hole (6) there is fitted a locking member (3) also provided with threadings (8), the said threadings being advantageously comparatively high-pitched so that by revolving the locking member (3) for half a circle at the most, the control shaft (1) can be locked into the aperture (5) of the lock device (2) or released therefrom. 4. The apparatus of claim 2 or 3, c h a r a c t e r i z e d in that the locking member (3) comprises a lever (4), and that the locking member (3) is revolved by winding the said lever (4). 5. The apparatus of claim 2, 3 or 4, c h a r a c t e r i ¬ z e d in that the aperture (5) of the lock device (2) is conical in such a manner that at least in one direction it is narrower in the middle than on the front and/or back surface of the lock device (2). 6. The apparatus of any of the preceding claims, c h a - r a c t e r i z e d in that in between the seat (9) and the frame (11) or equivalent, there is installed a member (-16; 17) which diminishes friction. 7. The apparatus of claim 6, c h a r a c t e r i z e d in that on the bottom surface of the seat (9) there is arranged at least one elongate, sliding guide (16; 17), supported by which the seat (9) can be moved within the limits of the adjusting range. 8. The apparatus of claim 7, c h a r a c t e r i z e d in that the guide (16) is arched in shape advantageously so that the guide rises from the front edge of the seat towards the rear edge. 9. The apparatus of any of the preceding claims, c h a ¬ r a c t e r i z e d in that in connection with the control shaft (1), there are arranged stoppers (18) for limiting the movements of the seat (9) and the back rest (10), and simultaenously for limiting the adjusting range. 10. The apparatus of claim 9, c h a r a c t e r i z e d in that the stoppers (18) are single separate members, a desired number of which can be installed at the first (la) or second (lb) end of the control shaft (1).

Inventors: SAARAINEN JORMA, SAARAINEN, JORMA
Applicants: SAARAINEN JORMA, SAARAINEN, JORMA
Application year: 1986
Main classification: A47C1
IPC codes: A47C1