Abstract:
A counterbalanced window operator includes a housing in which a rotatable lead screw, rotated by a crank handle or electric power unit, cooperates with a non-rotatable nut member to axially displace the nut member and move pivoting arms to open and close the window.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an operator unit for opening and closing a window and, more particularly, to a counterbalanced window operator. 
     Operators are known for moving a window between closed and open positions, for example, a window having a stationary main frame mounted in a roof of a house or other building, especially a sloped roof, and a sash hinged to the main frame at the top of the sash for pivoting toward and away from the main frame. Such operators are typically mounted on a bottom member of the main frame and connected to a bottom member of the sash for pushing the sash away from the main frame and drawing the sash into engagement with the main frame. When the window operator is actuated to move the window in an opening direction, it must overcome a component of the weight of the window, especially when the window is mounted in a roof. In order to overcome this difficulty, counterbalancing devices employing springs have been provided to counteract the weight component of the window and, thereby, reduce the force which must be applied to the operator, either by hand or by a power unit. Counterbalanced window operators are disclosed in U.S. Pat. Nos. 5,097,629 to Guhl et al. and 2,698,173 to Rydell. 
     SUMMARY OF THE INVENTION 
     The construction according to the present invention offers the advantage that a very compact design of high stability and functional reliability is obtained so that, in the closed condition of the window, the moving means of the operating member between the sash and the main frame may be completely accommodated in a fairly small housing mounted on the bottom of the main frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a first embodiment of a window operator according to the present invention; 
     FIG. 2 is a schematic view of a second embodiment of a window operator according to the present invention; 
     FIG. 3 is a schematic view of a third embodiment of a window operator according to the present invention; 
     FIG. 4 is a side schematic view of a fourth embodiment of a window operator according to the present invention; 
     FIG. 5 is a schematic view of a fifth embodiment of a window operator according to the present invention; 
     FIG. 6 is a cross section of a portion of a window sash to which the operator according to the present invention is connected; 
     FIG. 7 is a schematic view of a sixth embodiment of a window operator according to the present invention; 
     FIG. 8 is a right side view of the window operator of FIG. 7; 
     FIG. 9 is a schematic view of the window operator of FIG. 3 to which an electric drive unit, rather than a handle, is connected; and 
     FIG. 10 is a schematic view of a window having a rectangular main frame and a rectangular sash mounted for pivoting movement relative to the main frame and employing the window operator according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Common features of the embodiments of the counterbalanced window operator according to the present invention which are shown in FIGS. 1-5, 7 and 8 are that a connection between a sash of a window and an operator housing 1, 11, 21, respectively, which is mounted, e.g., at a bottom member of the main frame of the window, is provided by two pivoting arms 2-3, 12-13, 22-23, respectively, one end of each of which is pivotally journaled about a pivot point in the housing 1, 11, 21. The other end of each pivoting arm is pivotally connected with a bottom member S of the sash by means of slide shoes 2a-3a, 12a-13a, 22a-23a, respectively, slidably displaceable in the longitudinal direction of that member in tracks of a track member T secured on the bottom member S, as can be seen from FIG. 6. 
     The drive member for the opening movement is a non-rotatable nut member 4, 14, 24, respectively, engaged by the rotatable lead screw 5, 15, 25, respectively, operated by cranking the handle 6, 16, 26, respectively. A thrust bearing B1, B2, B3, respectively, is provided in the housing 1, 11, 21 to support the lead screw 5, 15, 25 for rotation and to withstand axial forces imposed on the lead screw. In the embodiment of FIGS. 7 and 8, thrust bearings B4 and B5 are used with a worm member 15a. 
     The connection between the nut member 4, 14, 24 and the pivotal arms 2-3, 12-13, 22-23 is provided by a symmetrical pair of links 7, 17, 27, respectively, having one end pivotally connected with the non-rotatable nut member 4, 14, 24 and another end pivotally connected with the respective arm 2-3, 12-13, 22-23 in a point 2b-3b, 12b-13b, 22b-23b, respectively, located at some distance from the end of the arm pivotally journaled in the housing 1, 11, 21. In the embodiment of FIGS. 7 and 8, a symmetrical pair of links 17a each has one end pivotally connected with a ratchet block 14a and another end connected with a respective arm 12-13 in a point 12b-13b located at some distance from the end of the arm pivotally journaled in the housing 11. 
     In each illustrated embodiment, a symmetrical arrangement of a counterbalancing spring mechanism is provided to facilitate the opening movement of the window by compensating for the weight of the window. 
     In FIG. 1, the counterbalancing mechanism comprises on each side a compression spring 8, such as a coil spring, pivotally connected at one end to the bottom member of the main frame outside the housing 1 and pivotally connected at an opposite end to the above-mentioned respective point 2b-3b at the respective arm 2-3 through a rigid bar member 9. Although a compression spring 8 is shown only on the right side of FIG. 1, it is understood that a like spring is connected to the rigid bar 9 on the left side of FIG. 1. As an alternative, tension springs can be used in place of the compression springs 8. 
     In the embodiment of FIG. 2, a tension spring 8a has been substituted for the compression spring 8. A similar tension spring (not illustrated) is connected to the rigid bar 9a on the left side of FIG. 2. The bracket member connected with the main frame of the window is located at the end of the spring 8a adjacent to the pivot arm 3, whereas the rigid bar 9a is connected with the opposite end of the spring 8a distal to the pivot arm 3. 
     In FIG. 3, the counterbalancing mechanism comprises a torsion spring 18 with two fingers 19 each curved around and engaging one of the pivoting arms 12-13, the torsion spring being mounted on a stationary pin 20 in the housing 11. 
     The embodiment of FIG. 4 is a modification of the embodiment of FIG. 3 in which links 17b between the non-rotatable nut member 14 and the arms 12, 13 allow the arms 12, 13 to pivot about an axis perpendicular to the axis of the rotatable lead screw 15. The connection between the links 17b and the pivot arms 12, 13, as well as between the links 17b and the non-rotatable nut member 14, comprise spherical joints, or ball-and-socket joints, 17c in the embodiment illustrated. Such joints permit the pivot arms 12, 13 to follow the opening movement of the bottom of the sash S as it pivots about the axis of the hinges at the top of the sash by which the sash is mounted on the main frame. The axis of the lead screw 15 is adjustable with respect to the main frame of the window by means of a slide member 20a, which is slidable in a curved slot 20b in a bracket 20c connected to the main frame and arrestable by means of arresting screws 20d. 
     In FIG. 5, the counterbalancing mechanism is provided by a laminated leaf spring 28 engaging and fixed at one wall 29 of the housing 21 and engaging the nut member 24. 
     As can be seen from FIGS. 7 and 8, which are views corresponding to the views of FIGS. 3 and 4, there is a different modification of the embodiment of FIGS. 3 and 4 by which the worm member 15a has been substituted for the threaded spindle or shaft 15 forming the screw member in FIG. 3. The non-rotatable nut member comprises in this case, not a head portion surrounding a threaded spindle, but rather two ratchet blocks 14a engaging the worm member 15a at diametrically opposite sides thereof. The ratchet blocks 14a are provided with tooth-like projections 14b engaging the worm member 15a. As can be seen in FIG. 8, this arrangement allows the axis of the screw member 15a to be inclined with respect to the ratchet blocks 14a, which are confined by guide members 14c, 14d to displacement in a plane parallel to the two arms 12, 13. 
     FIG. 9 shows an electric drive unit M connected to the lead screw 15 to drive the lead screw, instead of using the handle 16. The electric drive unit M can also be connected to the lead screws 5 and 25 of the other illustrated embodiments of the present invention rather than using the handles 6 and 26. 
     As can be seen from FIG. 10, the operator according to the present invention is for opening a window 30 having a generally rectangular main frame 32 and a generally rectangular sash 34 mounted for pivoting movement relative to the main frame about a pivot axis P generally parallel to a pair of opposed sides of the sash. 
     It will be apparent to those skilled in the art and it is contemplated that variations and/or changes in the embodiments illustrated and described herein may be made without departure from the present invention. For example, although the non-rotatable member has been described as a non-rotatable nut member 4, 14, 24, other members having threaded openings can be employed, and still other changes may be made. Accordingly, it is intended that the foregoing description is illustrative only, not limiting, and that the true spirit and scope of the present invention will be determined by the appended claims.