Limiting stop for the swinging angle of a pivoted arm
BACKGROUND OF THE INVENTION 
     The invention relates to a limiting stop for the swinging angle of an arm which is movable around a bearing axis wherein one end of a strut is pivoted to the structural part which carries the bearing axis and wherein the other end of the strut is pivoted to the arm at a distance from the bearing axis. 
     Such limiting stops are frequently required for example in the development field of building fittings. They are used for example to limit the opening angle of open-out arms for windows and doors relative to the stationary frame and/or to the closure member. 
     The installation space which is available for the accommodation of such limiting stops is frequently relatively small. It is, however, important that the limiting stops durably and reliably fulfill their intended function. 
     According to the invention, there is provided a limiting stop of this type which requires relatively little installation space and has high functional reliability and is of a structurally simple design. Such a limiting stop is distinguished in that the strut consists of two structurally similar links, each having a longitudinal slot and a stop tongue which extends laterally from the plane of the link. the stop tongue of each link is slidably engaged for lengthwise movement in the elongated slot of the other link. The elongated slot of each link has a stop end which lies adjacent to its top tongue. The end of each stop tongue has laterally projecting supporting flanges which can enter the slot through an enlarged end of the slot which is distant from the stop end of the slot, and can be brought into supporting engagement with the longitudinal edges of the slot. The relative displacement of the links is less than the distance between the stop end and the enlarged end of the elongated slot of each link. 
     In accordance with one embodiment of the invention, the outwardly facing end of one link is pivoted on the structural part which carries the bearing axis. The outwardly facing end of the other link is pivoted on the arm. In another embodiment of the invention, the links of the strut consist of strip material with flat-rectangular cross section. 
     It is obvious that the links for forming a limiting stop in accordance with the invention can be easily and simply fabricated as punched and bent parts and that two of these links can be assembled through simple plug coupling connections into a strut which serves as a limiting stop which is adjustable lengthwise within given limits. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The subject matter of the invention is represented in the drawing in an exemplified embodiment in which: 
     FIG. 1 a top view of a limiting stop in operative connection with a carrying and guiding system for the closure member of a window, of a door or the like, the limit stop being shown in the operative stoping position, and 
     FIG. 2 a longitudinal cross section through the limiting stop mechanism of FIG. 1 but shown in the contracted or non-stoping position. 
    
    
     In FIG. 1 of the drawing, the stationary frame 1 of a window, of a door or the like, is shown in diagrammatically simplified presentation, that is, by means of a dot-dash line a planar closure member 3 is suspended within the frame and is swingably movable relative to the frame. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The carrying and guiding system which is generally indicated by the reference numeral 2 includes arm 4 which is suspended for swinging movement about a pivot pin axis 5 at a stationary frame 1. Two guide levers 8 and 9 are pivotally connected to the supporting arm 4 by means of two pivot pins 6 and 7 respectively. The levers 8 and 9 are of equal length. The guide levers 8 and 9 are, in turn, connected by pivot pins 10 or 11, respectively to a guide rail 12. The guide rail 12 is parallel with and secured to the closure member 3. The portion of the supporting arm 4 which lies between the pivot pins 6 and 7 forms, with the two guide levers 8 and 9 as well as with the guide rail 12, a guide parallelogram which is generally indicated by the reference numeral 13 Parallelogram 13 connects the closure member 3 with the stationary frame 1 The movement of the guide parallelogram 13 is affected through a control guide lever 14. One end of the control guide lever 14 is swingably suspended at the stationary frame at a bearing axis 5. The other end of the lever 14 is pivotally connected by a pivot pin 16 to the guide lever 8 at a point between the pivot pins 6 and 10. The control guide lever 14 affects the movement of the guide parallelogram 13 so that the closure member 3 is guided on its opening and closing motion along a path which is at least approximately limited by circular curves around a latent hinge axis which lies in the proximity of the side edge of the wing 3 adjacent to the bearing site. 
     In order to avoid injuries at the window or at the door as well as on the support and guide element system 2 it is necessary to limit the swinging angle for the supporting arm 4 around its bearing axis 5, for example to 90° to the plane of the stationary frame 1. A strut 17 functions as a limit stop for the swinging angle of the supporting arm 4. One end of the strut 17 is swingably suspended at a bearing axis 18 to the stationary frame 1. The other end of strut 17 engages the supporting arm 4, for example, through the hinge pin 6 at a point which is spaced from the bearing axis 5. 
     The strut 17 comprises two structurally similar overlapping links 19a and 19b. Each of the links 19a and 19b has an elongated slot and a stop tongue at one end of the link which extends at an angle to the plane of the link. The link 19a has a slot 20a and a stop tongue 21a. The link 19b has a slot 20b and a stop tongue 21b. The stop tongue of each link engages the elongated slot of the other link for lengthwise movement along the slot. The end of the elongated slot of each link which is nearest the stop tongue of the link acts as a stop end for the tongue of the other link. The slot 20a of link 19a has a stop end 22a and the slot 20b of the link 19b has a stop end 22b. In the fully extended position of the strut 17 as shown from FIG. 1, the distance between the pivot pins 6 and 18 is limited to the distance which is indicated by the reference numeral 23. When the strut 17 is in this extended position, the stop tongue 21a of the link 20a engages the stop end 22b in the elongated slot 20b of the link 19b, while the stop tongue 21b of the link 19b engages the stop end 22a in the elongated slot 20a of the link 19a as may clearly be seen in FIG. 1. 
     In order that the links 19a and 19b which form the strut 17 can be assembled and held together in a simple manner, each stop tongue 21a and 21b has, at its free end, a laterally projecting retaining flange. The stop tongue 21a has retaining flanges 24a and the stop tongue 21b has retaining flanges 24b. The retaining flanges 24a and 24b of each tongue are brought into supporting and holding engagement with the longitudinal edges of the elongated slot of the other link through an enlarged end at the end of the elongated slot which is remote from the stop end of the slot. Slot 20a has an enlarged end 25a and slot 20b has an enlarged end 25b. 
     In the contracted position as shown in FIG. 2, the distance between the axis 16 and 18 is indicated by the reference numeral 26. The difference between the distance 23 and 26 represents the relative displacement of the links 19a and 19b. The relative displacement of the links 19a and 19b between the extended position shown in FIG. 1 and the contracted position of FIG. 2 is less than the distance between the stop end and the enlarged end of the slot. A undesired and automatic uncoupling of the lashings 19a and 19b forming the strut 17 is thereby avoided in a simple manner. 
     The two links 19a and 19b are identical and can therefore be fabricated with the same tool, as punched and bent parts out of strip material of flat-rectangular cross section. It is important that the stop tongues 21a and 21b of the two links 19a and 19b respectively engage for lengthwise movement within their assigned elongated slots 20b and 20a respectively while the free ends of the strut 17 are held on the pivot pins 6 and 18 for lengthwise movement. 
     The utilization of the strut 17 as a limiting stop for the swinging angle of an arm which is movable around a bearing axis is not necessarily limited to the support and guide system 2 as shown in FIG. 1. The limiting stop which is formed through the strut 17 can be used wherever the object is to limit the swinging angle for an arm which is movable around a bearing axis relative to the structural part which carries a bearing axis. 
     after assembly of the links 19a and 19b into the strut 17, it is also possible to press into the enlarged ends 25a and 25b of the elongated slots 20a and 20b filler pieces, e.g. of plastics, in a detent-like manner in order to prevent undesired decoupling of the links. 
     SUMMARY OF THE INVENTION 
     A limit stop for the swinging angle of an arm 4 which is movable around a pivot pin 5, such as is used for example as open-out arm between the closure member 3 and the stationary frame of a window or a door. The limit stop requires only a small installation space , has high functional reliability and is of a structurally simple construction. For this purpose, one end of a strut 17 is fastened through a pivot pin 18 on the structural part which also carries the pivot pin 5. The other end of the strut 17 is pivotally connected by a pivot pin 6 to the arm 4 at a distance from the pivot pin 5. The strut 17 consists of two structurally-similar links 19a, 19b. Each link has an elongated slot and a stop tongue which is spaced from the stop tongue of the other link and which is also bent off from the plane of the links. The stop tongue of each link 19a, 19b is, in each case, inserted for lengthwise movement in the elongated slot of the other link. The stop end 22b  or 22a of the elongated slot of each link lies adjacent the stop tongue of the link. The end of each stop tongue has laterally projecting retaining flanges (24a,24b) which can be brought into supporting engagement with the longitudinal edges of the elongated slots of the links (25a,25b) which is spaced from the stop end of the elongated slot. The relative displacement of the links 19a and 19b can be limited to a length which is less than the distance between the stop end 22a or 22b and the enlarged end 25a or 25b of the elongated slots 20a or 20b of each link 19a or 19b.