Abstract:
A fitting for an item of seating furniture and item of seating furniture. 
     The fitting includes a pivotable leg support segment, wherein the fitting has a separate spring which serves to secure the leg support segment in a storage position while not being used.

Description:
FIELD OF APPLICATION AND PRIOR ART 
     This application claims the priority of the German patent application No. 10 2012 214 541.9. The whole disclosure of this prior application is herewith incorporated by reference into this application. 
     The invention relates to a fitting for an item of seating furniture and to an item of seating furniture having such a fitting. 
     Such a fitting for an item of seating furniture comprises the following components: It has a base for a fixed in position arrangement or an arrangement rotatably movable around a vertical axis on a ground. It comprises a support part to which the seating surface of the item of seating furniture is attached according to the designated purpose, wherein said support part is movable relative to the aforementioned base between a front end relative position and a rear end relative position with respect to a furniture longitudinal axis. For the purpose of said relative movability of the support part, it comprises furthermore a front and a rear rigid bracket, wherein the front bracket is pivotable relative to the base about a first axis fixed in position to the base and to the first bracket and relative to the support part about a second axis fixed in position to the support part and the front bracket. The rear bracket is pivotable relative to the base about a third axis fixed in position to the base and to the rear bracket and relative to the support part about a fourth axis fixed in position to the support part and the rear bracket. Furthermore, the fitting comprises a leg support part for attaching a leg support, which part can be pivoted between a storage position underneath the base and a functional position in front of the base and the relative position thereof to the base is forcedly-coupled to the relative position of the support part relative to the base such that the leg support part takes the functional position when the support part is arranged in its rear end relative position and takes the storage position when the support part is arranged in its front end relative position. 
     Furthermore, such a fitting also comprises a first spring between a first and a second coupling point at the support part and the base part, which spring causes a force application to the support part in the direction of its front end position. 
     Such items of furniture are known at least from the internal prior art. The base is that part which is preferably arranged fixed in position and, at the most, rotatably on a ground, i.e. a floor area. According to the invention, it is connected to a furniture foot or comprises said foot. The support part, which in the assembled state of the fitting supports the seating surface, is movable relative to the base, wherein that is effected via the aforementioned front and rear bracket. In this case, usually provision is made for in each case a plurality of front and rear brackets, which are pivotable around identical pivot axis. As far as reference is made to the front or to the rear bracket, respectively, in connection with the present document, that shall also refer to a plurality of such brackets. 
     By means of the support part, the base and the front and the rear bracket, a system of four segments is formed, which in a closed catenary are movable relative to one another due to the four axes parallel to one another. Said movability serves to displace the support part of the seating surface backwards if a person sits on the respective item of seating furniture. Said displacement of the support part backwards is connected to a displacement of the aforementioned leg support part, which as a result is pivoted from a storage position into the functional position. The aforementioned catenary of four segments results in that the base part can only move along a defined path relative to the base. To each position of the support part is assigned a pivot angle of the support part determined by the length of the brackets. 
     The first spring which is usually present in such items of furniture and which is preferably also present in the item of seating furniture according to the invention and the fitting thereof pushes the support part in the direction of its front end relative position, what pushes the leg support part in the direction of its storage position due to the forced coupling to the leg support part. Said spring serves to dampen the displacement of the support part from its front end relative position into its rear end relative position, when in particular a heavy person sits on the respective item of seating furniture. Said spring usually provided in items of furniture known from the prior art is generally configured comparatively softly. 
     Although said spring generally acts in such a way that the support part is pushed in the direction of its front end relative position and as a result the leg support part is pushed in the direction of its storage position, said spring is not sufficient to keep the leg support part reliably in the storage position. Especially if said leg support part is provided with a massive upholstering, the first spring cannot ensure a reliable reaching of the storage position. 
     In the abovementioned prior art known at least internally it is provided that exterior to the fitting, that is to say exterior to the left and right side walls of the base part, further springs are provided, which act between base and leg support part and which pull the leg support part continuously into the direction of its storage position, wherein in the course of the transfer of the leg support part into its functional position, a dead center position is surpassed so that said springs are also suitable to secure the functional position of the leg support part. 
     However, the problem regarding such known springs is that they would be very much expanded in the case of great pivot angles of the leg support part, so that expansion forces would be required in order to ensure the desired functioning, which at the same time would cause a sluggishness in the transfer of the leg support part into its functional position. Furthermore, the aforementioned springs usually provided externally of the side walls are problematic since they are arranged almost horizontally just as the first spring and thus need to be adjusted specifically to the first spring. In the case of a change of individual components of the fitting or of the furniture comprising the fitting, significant adjustments would be required. Thus, for example, a change of the upholstering and of the weight of the upholstering can result in that the first spring or the known additional springs acting on the leg support need to be re-configured. 
     Object and Solution 
     Thus, the object of the invention is to develop such a furniture fitting further such that said fitting is capable of securing the leg support segment in its storage position. 
     According to the invention, that is achieved in that a second spring is provided which on the one hand is coupled to a third coupling point, which is spaced apart from the first coupling point and the second coupling point, at the support part and on the other hand to a fourth coupling point at the base part and which spring acts between the support part and the base part, when the leg support part approaches its storage position, such that the leg support part is applied with a force into the direction of its storage position. 
     Thus, according to the invention, besides the first spring which is to effect the above described dampening effect, a second spring specifically provided therefor is to be attached to the fitting, which second spring serves for securing the storage position of the leg support part. Said spring is to be attached to coupling points differing from the coupling points of the first spring and thus acts geometrically different. In contrast to known designs, it does not directly act on the leg support part but between the base part and the support part and uses the forced coupling of their relative position to the position of the leg support part. As a result of such a specific second spring, which can be arranged such that it causes a relevant effect only in the region of the storage position of the leg support part by means of measures yet to be explained in the following, the storage position of the leg support part can reliably be secured. 
     The second spring is preferably provided in a front region of the fitting, i.e. in the region of the front bracket. At said front part also the leg support part is provided, which is preferably connected such that it is always pivoted together with the front bracket in the same direction. 
     It is particularly advantageous if the second spring is arranged such that it causes the desired effect when the leg support part approaches the storage position, but that it does not cause an adverse effect and in particular preferably performs energetically almost neutral if the leg support part has a greater distance to its storage position. 
     It turned out that this can be achieved when the distance of the coupling points of the second spring relative to the first and the second axis are subject to certain principles. 
     Thus, it is particularly advantageous when the third coupling point of the second spring, i.e. the coupling point at the base part, is spaced apart from the second axis, i.e. the pivot axis of the front bracket. Preferably, said spacing is between 5 mm and 50 mm. In analogy, with respect to the fourth coupling point of the second spring, i.e. the coupling point of the base, and the first axis, i.e. the base-sided axis of the front bracket, it is provided that here a spacing is provided which is preferably between 5 mm and 40 mm. 
     In connection with said geometric data, the following information is relevant for a better understanding: The measures according to the invention can well be explained by means of an analysis of the fitting as a two-dimensional fitting. Unless otherwise provided in the following, the respective indications regarding the spacing of axis and coupling points refer to a projection of the fitting to a plane which is spanned by the furniture vertical direction and the furniture longitudinal direction. The aforementioned axes extend in the furniture transverse direction, i.e. orthogonally to said projection plane. 
     By means of the proposed spacing between the first axis and the fourth coupling point and between the second axis and the third coupling point it is achieved that the indirect effect of the second spring on the leg support part can change over the pivot distance between the storage position and the functional position. However, by means of the but small spacing, it is achieved that the second spring during the aforementioned transfer from the storage position of the leg support part to the functional position is only slightly expanded, which is advantageous with respect to the simple arrangeability of the second spring. 
     In order to achieve the effectiveness of the spring in a particularly advantageous manner, when the leg support part is close to its storage position, and in order to achieve the neutralization of the second spring, when the distance of the leg support part to its storage position is comparatively great, the relative arrangement of the third and of the fourth coupling point as well as of the first and second axes can advantageously be configured as follows. 
     Firstly, it is advantageous if a first connection straight in the aforementioned projection plane, which extends between the first axis and the second axis, includes an angle with a second connection straight extending between the third and the fourth coupling point that is greater in the front end relative position of the support part and thus in the storage position of the leg support part than in the rear relative position of the support part and thus in the functional position of the leg support part. Said greater angle results in that in the storage position of the leg support part, the effect of the second spring extending into the direction of the second connection straight is particularly important, since the respective force vector in the direction orthogonal relative to the first connection straight becomes comparatively great. As a result of the smaller angle included in the functional position of the leg support part, the respective force vector in the functional position is essentially smaller and thus the effect of the second spring is significantly reduced. 
     The aforementioned connection straights include an angle of &gt;10°, in particular of &gt;15°, in the front end relative position of the support part and thus in the storage position of the leg support part. In the opposite rear end relative position of the support part and thus the functional position of the leg support part, said angle is preferably less than 10°, in particular preferably less than 5°. 
     With respect to a pivot movement of the leg support part, it is of particular advantage when starting from a storage position of the leg support part, the pivot movement of the leg support part in the direction of its functional state results in a continuous decrease of the angle between the two connection straights during the first 30° of said movement, mainly within the first 15°. 
     With respect to the storage position of the leg support part, it is of particular advantage when the second spring is configured such and adjusted to the position of the third and of the fourth coupling point that the spring force of the second spring is at least 20 N. By means of that, the storage position of the leg support part can well be ensured. 
     Even though a plurality of second springs may be provided, which have identical coupling points with respect to the aforementioned projection plane, it is of advantage that only one such spring is provided which is in particular preferably arranged between two external side wall parts of the base. Thus, in the assembled state of the fitting the spring is hardly visible from the exterior so that the aesthetic appearance of the respective furniture is not interfered. 
     Preferably, the spring is a helical spring, wherein in particular preferably the length of said helical spring in the relaxed state does not surpass 200 mm, in particular preferably 150 mm. 
     Besides to the fitting, the invention also relates to an item of seating furniture equipped with such a fitting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and aspects of the invention result from the claims as well as from the following description of a preferred exemplary embodiment of the invention, which is explained by means of the drawings. Here: 
         FIGS. 1 and 2  show a furniture fitting according to the invention in a storage position and in a functional position, and 
         FIGS. 3A to 3H  show the fitting of  FIGS. 1 and 2  each in a perspective view and in a sectional side view during the transfer from the functional position of  FIGS. 3A and 3B  into the storage position of  FIGS. 3G and 3H . 
     
    
    
     DETAILED DESCRIPTION 
     At first, by means of the  FIGS. 1 and 2  the essential elements of the fitting and the two positions shown are explained. 
     The fitting  10  shown comprises a base  20  and front brackets  30  and rear brackets  40  pivotably coupled to said base about a first axis  1  and a third axis  3 , respectively. The respective opposite ends of the brackets  30 ,  40  are pivotably coupled to a support part  50  around a second axis  2  and a fourth axis  4 , respectively. 
     The base is intended to be provided with a furniture foot which allows fixed in position arrangement of the base relative to a ground or the rotatable arrangement of the base relative to a ground. The support part  50  serves for fixation of the seat surface. The base  20 , the support part  50 , as well as the front brackets  30  and the rear brackets  40  together form a closed catenary of four segments, which are connected to one another via the aforementioned axis  1 ,  2 ,  3 ,  4 . By means of the front and the rear brackets  30 ,  40 , a movability of the support part  50  is given, which becomes clear by means of the two positions of  FIGS. 1 and 2 . 
     The support part may take a front end position with respect to a furniture longitudinal axis  100 , as shown in  FIG. 1 , and a rear relative end position as shown in  FIG. 2 . In this case, due to the different lengths of the front and the rear brackets  30 ,  40 , the support part is pivoted. In its rear relative end position of  FIG. 2 , it is tilted by approximately 12° relative to its orientation in the front end relative position of  FIG. 1 . 
     A leg support part  70  pivotably coupled around a pivot axis  5  is adjacent to a front end of the base  20 . As can be seen from  FIGS. 1 and 2 , said leg support part  70  is in a storage position, which is shown in  FIG. 1 , when the support part  50  is in its front end position. If the support part  50  is in its rear end position, as shown in  FIG. 2 , the leg support part is in a functional position. In an upholstered form, it may serve as a support for the legs of a person sitting on the item of furniture. 
     The movement of the leg support part  70  together with the movement of the support part  50  is forced-coupled relative to the base  20 . That is achieved in that the leg support part  70  is not only coupled to the base  20  pivotably about the pivot axis  5 , but also to the support part  50  by means of an additional bracket  60 . 
     The fitting  10  comprises a first spring  80 , the rear first coupling point  81  of which is provided on the support part  50  and the front second coupling point  82  of which is provided to a traverse  22  associated to the base  20 . In this context, it is to be noted that due to limitations of the graphical software with which the figures were produced, the first spring  80  seems to be not hooked into its rear coupling point. However, this is true for the assembled state of the fitting. 
     The first spring  80  is expanded as illustrated in  FIGS. 1 and 2 , when the support part  50  is displaced into its rear end relative position. Said spring serves to not turn the force application to the support part  50  into an immediate and abrupt transfer of the fitting from the state of  FIG. 1  into the state of  FIG. 2  as a result of a person sitting down on the seating surface. Instead, said transfer is to be dampened. The first spring  80  is configured to that end. Although the first spring  80  acts such that force is applied to the support part  50  in the direction of its front relative end position of  FIG. 1  and that is to cause the pivoting of the leg support part  70  into the storage position of  FIG. 1  due to the forced-coupling, the spring force of the first spring  80  is not sufficient to retain the leg support part  70  in the position of  FIG. 1 . However, a stronger first spring  80  would prevent the functioning of the fitting as a whole. 
     Therefore, a second spring  90  is provided which extends between a third coupling point  93  on the support part  50  and a fourth coupling point  94  on the traverse  22  of the base part  20 . The second spring  90  is arranged centrally with respect to a furniture transverse axis  102 , so that it is not visible when the fitting  10  is integrated in a furniture. The aforementioned second spring  90  serves to pull the leg support part  70  in the storage position of  FIG. 1 . In order to permit that, without—as a result—causing the undesired effect that the second spring  90  aggravates the transfer of the fitting  10  and in particular of the leg support part  70  into its functional position of  FIG. 2 , a design of the relevant geometrical relations is provided which is explained by means of the lower side illustration of  FIGS. 3A and 3B . 
     Said lower illustration shows the projection plane mentioned above already, which plane is defined by the furniture vertical axis  104  and the furniture longitudinal axis  100 . In  FIGS. 3A and 3B  the first and the second axis  1 ,  2  as well as the third coupling point  93  and the fourth coupling point  94  of the second spring  90  are indicated. For a better understanding, the second spring  90  is not shown as in  FIGS. 3C to 3H . 
     Since both the second axis  2  and the third coupling point  93  are provided at the support part  50 , they are spaced from one another in the projection plane of  FIGS. 3A and 3B , at the bottom, in an unchanged manner, in this case by almost 40 mm. Since also the first pivot axis  1  and the fourth coupling point  94  are provided at a common component, namely the base  20 , they are also spaced apart from one another at a constant distance, in this case by approximately 25 mm. 
     In the embodiment of  FIGS. 3A and 3B , in which the leg support part  70  is in its functional state and the support part  50  is in its rear relative end position relative to the base part  20 , a first connection straight  111  which crosses the first and second axis  1 ,  2  and thus represents the orientation of the front bracket  30 , is almost parallel to a second connection straight  112  which crosses the coupling points  93 ,  94  and thus represents the extension of the second spring  90 . The angle included between the two straights  111 ,  112  is significantly smaller than 10°. 
     Said small angle results in the spring force almost not causing any effect since its force vector parallel to the first connection straight  11  is almost identical to its resulting force vector. The orthogonal force vector actually resulting in an effective force application to the support part  50  relative to the base  20  is comparatively very small. 
     If starting from said starting position of  FIGS. 3A and 3B , a transition into the end state of  FIGS. 3G and 3H  is effected, the leg support part  70  is pivoted at the same time, with respect to  FIGS. 3A and 3B  at the bottom, counterclockwise, while the support part  50  is displaced forwards with respect to the furniture longitudinal axis  100 . 
       FIGS. 3C to 3F  show that this does not result in an increase of the angle included between the connection straights  111 ,  112  over the major part of the pivot distance of the leg support part  70 . Indeed, the included angle gets smaller, at first. However, if the movement of the leg support segment in the direction of its storage position of  FIGS. 3G and 3H  is continued, said angle gets greater again until reaching its maximum in the storage state of the leg support part  70  in  FIGS. 3G and 3H . In said state, the angle is 17°, so that a relevant part of the spring force provided by the second spring  90  is available in the form of a force vector orthogonal to the first connection straight  111 . In the state of  FIGS. 3G and 3H , said effective part of the spring force of the spring  90  pulls down the support part  50  in the region of its front end, whereby due to the described forced coupling the leg support part  70  is pushed in the direction of the storage position of  FIGS. 3G and 3H  and is thus reliably secured in said storage position. 
     In the case that the transition from the storage position of  FIGS. 3G and 3H  into the functional position of the leg support part  70  of  FIGS. 3A and 3B  is desired in the opposite direction, the second spring  90  causes a significant effect but over a very small pivot angle of the leg support part  70  of approximately 15°. Upon leaving said pivot region, what approximately corresponds to the state of  FIGS. 3E and 3F , the spring  90  performs energetically almost neutral due to the present almost parallel orientation relative to the connection straights  111 ,  112  and thus does not interfere with the transfer of the leg support part into the functional state of  FIGS. 3A and 3B .