Abstract:
A push pull chain is provided with chain links that are connected to each other by respectively one chain joint, designed in a space-efficient manner. The chain joints of a first chain section with their joint axes have a first orientation, whereby the joint axes of the chain joints of a second chain section are arranged in a second orientation that is twisted around the longitudinal axis of the push pull chain or whereby they can be set to this orientation. In addition, a pertaining chain drive is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to foreign European patent application No. EP 14001818.5, filed on May 23, 2014, the disclosure of which is incorporated by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention concerns a push pull chain with chain links that are connected to each other respectively by one chain joint. 
       BACKGROUND 
       [0003]    Push pull chains can be found in diverse forms in the state of the art. In most cases, they are plate-link chains with alternating internal and external chain links that are connected by means of a chain joint. The internal and/or external plate links or special stiffening brackets (links) are shaped in a way that the chain can be made bend-proof in one swivel direction of the chain joint. This is ensured for a lineally guided (straight) chain or slightly over-swiveled chain joints so that thrust powers can be subsequently transmitted. The chain joints can still be swiveled in the other swivel direction and the chain can be guided accordingly, i.e. around a chain wheel. Also the drive of such a chain is generally ensured by means of a chain wheel. Of course, these chains can usually also transmit traction forces. Push pull chains which belong to the class of anti-backbend chains are used, for example, in door locking systems, window lifting systems etc. The use of push pull chains occasionally requires more space especially if the chain is to be rolled up for the purpose of storage or for the drive. In some cases, this space requirement hampers the use of push pull chains. 
       SUMMARY OF THE INVENTION 
       [0004]    Hence, the purpose of the present invention consists of providing a push pull chain of the type mentioned initially, which can be used more flexibly and which allows for a greater storage leeway. 
         [0005]    This problem is solved by the invention due to the condition that the joint axes of chain joints of a first chain section have a first alignment and that the joint axes of the chain joints of a second chain section are installed in a second alignment, that is twisted around a longitudinal axis of the push pull chain, or that they can be set into this twisted alignment. 
         [0006]    Thanks to this distribution, the push pull chain can be divided for example into a driven part and an operational part which are guided towards each other in a different twisting direction in relation to the longitudinal chain axis. Hence, the chain can not only be guided and rolled up in one plane, but be positioned at least in two different planes. The level of flexibility of a push pull chain has been two-dimensional up to present. Through the proposed solution, the level of flexibility of the push pull chain is extended by at least one dimension in a thrust and traction direction. This enables the implementation of complex kinematic structures. The flows of force in these kinematics can be transmitted in traction as well as in thrust directions. Especially the compactness of drives for the push pull chain is extended by one dimension as the storage of the push pull chain in a drive is now independent of the operational direction of the chain. For example, the operational direction could be aligned perpendicularly to the roll-up or insertion plane of the push pull chain in the drive. 
         [0007]    The first chain section and the second chain section are preferably connected to each other by means of a linking piece that predetermines or that can trigger the twist. The linking piece can either predetermine a fixed twisting angle or provide several twisting angles, also in a stepless manner. 
         [0008]    In another design variant, each chain section is planned to comprise internal and external chain links that are interconnected in an alternating way by means of respectively one chain joint, whereby each chain joint shall consist of a chain bolt of the external chain link and a sleeve (bush or bushing) of the internal chain link. This is the most common structure of a link chain. The chain bolts are respectively guided in the sleeves in a rotatable manner. 
         [0009]    The linking piece can conveniently have a first junction point for the connection with the first chain section and a second junction point for the connection with the second chain section and the junction points can twist the first and the second chain section in an angle ranging from 30° to 150°, preferably 60° to 120°, especially 90°, towards each other. Therefore, it can be adapted to the particular drive situation and the suitable angle can be chosen whereby the angle of 90° has a special significance. 
         [0010]    Alternatively, the linking piece can have a first junction point for the connection with the first chain section and a second junction point for the connection with the second chain section, whereby the first and the second junction points are arranged twistably towards each other by means of a rotary joint installed in between. Such a design variant offers the possibility of using the same push pull chain for a variety of drive situations in which different twisting angles are required. In addition, there is the possibility to start twisting only during the guiding process of the push pull chain. 
         [0011]    In another design variant, the linking piece is planned to have two holes as junction points in which there is respectively one chain bolt of the internal chain link. Thereby, the chain bolt maybe pivotably received or fixedly fastened in the holes. This depends essentially on whether the linking piece is also meant to be deflected. In addition, fixedly fastened chain bolts do not require a respective stiffening contour on the linking piece. 
         [0012]    Alternatively or in addition, the linking piece can have a stiffening contour for the first chain section and/or a stiffening contour for the second chain section. This is particularly suitable in cases where the linking piece should be guided relatively closely to the deflection point. 
         [0013]    If a push pull chain is required that also supports more complex kinematic structures, more than two chain sections can be installed out of which at least two are aligned in a twisted position towards each other or can be set to this twisted alignment towards each other. There is a variety of combination possibilities in this context. Either all chain sections can respectively be arranged in a twisted position towards each other or chain sections, that are to be installed separated from each other in the chain sling, can have the same twisting orientation whereas at least one other chain section has an orientation that is twisted in relation to the first one. 
         [0014]    In another design variant, the linking piece is designed to work as a functional component with an additional feature to transmit force in the longitudinal chain direction. This shall refer to features that have an activating or moving effect on elements that are mostly independent of the chain. The linking piece could be used, for instance, as an opening or closing slider for a door or a window. 
         [0015]    Besides, the invention also refers to a chain drive with a push pull chain according to one of the claims  1  to  9 , a drive that meshes with the first chain section and a deflector system that meshes with the second or further chain section and that deflects the second or further chain section. The push pull chain is used as a 3D chain and can consequently be deflected and/or guided in two different spatial planes. This offers the possibility, for example, to arrange the chain section that interacts with the drive in a space-efficient manner so that less voluminous structures are required. This enables, for instance, the installation in a plane that is arranged perpendicularly to the operating direction of a second or further chain section. 
         [0016]    The deflector system can preferably be a chain wheel and/or a guideway and/or a tension rail. This provides a variety of creative margins for a space-efficient installation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    In the following, the invention is explained in greater detail by means of a drawing. It shows: 
           [0018]      FIG. 1  a section of a push pull chain according to the invention, 
           [0019]      FIG. 2  the linking piece from  FIG. 1  in a perspective view, 
           [0020]      FIG. 3  a perspective view of a chain drive according to the invention, 
           [0021]      FIG. 4  the chain drive from  FIG. 3  in a top view, 
           [0022]      FIG. 5  the chain drive from  FIG. 3  in a front view and 
           [0023]      FIG. 6  the chain drive from  FIG. 3  in a lateral view. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The push pull chain  1  shown in  FIG. 1  comprises a first chain section  2  and a second chain section  3  that are connected to each other in a twisted way around the longitudinal axis L of the push pull chain  1  by means of a linking piece  4  installed in between. 
         [0025]    The first and the second chain section  2  and  3  respectively consist of alternatingly interconnected internal and external chain links  5  and  6 . 
         [0026]    Each internal chain link  5  consists of two internal plate links  7  arranged in parallel and two plate links, not shown in the figure, that connect these plate links with each other. A roll  8  is installed rotatably on each of the sleeves. 
         [0027]    Each external chain link  6  consists of external plate links  9  that are arranged in parallel and at a distance to each other and of chain bolts  10 , installed in the spacing division of the chain  1 , that connect these plate links to each other. Therefore, the chain bolts  10  are pressed into the external plate links  9  in appropriate apertures. 
         [0028]    To form a chain joint, a chain bolt  10  of the external chain link  6  extends respectively through a sleeve of the internal chain link  5 . 
         [0029]    Stiffening brackets (stiffening links)  11  are arranged between the internal plate links  7  and the external plate links  9 . Their contour is designed in a way as to encompass a part of the external circumference (approx. 157.5°). The stiffening brackets  11  each have a stop surface  12 . Adjacent stop surfaces  12  come in contact in case of a straight chain guide (this corresponds to a support angle of 0°, but a deviation of up to +5° or −5° is also possible) and hence lead to a stiffening effect in one direction while the respective chain section  2  and  3  can bend in the other direction by up to approx. 45° due to the contour of the stiffening brackets  11 . The first and the second chain section  2 ,  3  are twisted in relation to each other by an angle of 90° so that the pertaining chain bolt axes are also aligned perpendicularly to each other. The chain bolt axes of the first chain section  2  are arranged in parallel to each other and the chain bolt axes of the second chain section  3  are respectively installed in parallel to each other. The external and internal chain links  6 ,  5  are preferably made of a steel material. 
         [0030]    Now, the linking piece  4  shall be explained in greater detail by means of  FIG. 2 . The linking piece  4  has two holes  13  and  14  that are twisted in relation to each other by an angle of 90° and in the spacing division of the chain  1 . A chain bolt  10  of the first chain section  2  extends through the hole  13  and a chain bolt  10  of the second chain section  3  extends through the hole  14 . In the present case, the linking piece is a massive metal piece, e.g. made of steel or aluminum. The width of the linking piece  4  is designed in a way that it aligns with the outer surfaces of the stiffening brackets  11 . The respective front areas are rounded cylindrically. Stop surfaces  15  shall be developed on the linking piece  4  that can come in contact with the respective stop areas  12  of the pertaining stiffening brackets  11 . The respective contact surfaces  15 . 1  and  15 . 2  always extend only from the associated hole  13 ,  14  up to the outside. The contouring on the opposite side is designed in a way that an appropriate bend of the chain  1  continues to be possible. 
         [0031]    In the following, ways of using the push pull chain  1  according to the invention in a chain drive shall be explained in greater detail by means of the  FIGS. 3 to 6 . 
         [0032]    The chain drive  16  comprises two chain wheels  17 ,  18  whose axes are perpendicular to each other and at a distance from each other. Also, each of the chain wheels  17 ,  18  is associated with a U-shaped guiding  19  on the outside. The figures show very clearly that the push pull chain  1  is not only positioned in one plane but in a three-dimensional space. This provides different driving and installation possibilities and the chain can be used both in a thrust as well as in a traction mode. This is particularly advantageous if each chain section  2 ,  3  has a different function. For example, the second chain section  3  can predetermine an operating direction for the chain. Therefore, the second chain section  3  does not have to be led completely around an associated chain wheel  17 , but a 90° deflection could also be sufficient. Due to this, thrust forces in a perpendicular direction to the plane, spread out by the first chain section  2 , can also be applied. The drive function for the entire strand can be attributed to the first chain section. The chain wheel  18  would then be responsible for both the thrust as well as for the traction forces as a drive. This would also come with the possibility of positioning the chain in another plane. For example, the chain could be rolled up in the drive area or stored space-efficiently, i.e. in a straightened way, in the insert. Also here, it could be advantageous to guide the first chain section  2  around the push pull chain wheel  18  by only 90° so that the section of the first chain section  2  guided beyond could then be installed in a storage space perpendicularly to the plane that is spread out by the second chain section  3 . Hence, there are spacing benefits due to the installation possibility in a perpendicular position to the operating direction. 
         [0033]    The linking piece  4  can also be designed in a way that a rotary joint is arranged between the two holes  13 ,  14 , so that any angle position of the two chain sections  2 ,  3  towards each other can be supported. However, there is also the possibility of limiting and/or fixing the twisting effect of the rotary joint. In addition, the linking piece  4  can also be designed as a functional component. This can be ensured, for example, by means of actuating additional elements by the chain drive  16  by means of the linking piece  4 . 
       REFERENCE LIST 
       [0000]    
       
           1  Push pull chain 
           2  First chain section 
           3  Second chain section 
           4  Linking piece 
           5  Internal chain link 
           6  External chain link 
           7  Internal plate links 
           8  Roll 
           9  External plate links 
           10  Chain bolt 
           11  Stiffening bracket 
           12  Stop surface 
           13  Hole 
           14  Hole 
           15 . 1 , 15 . 2  Stop surface 
           16  Chain drive 
           17  Chain wheel 
           18  Chain wheel 
           19  Guiding system