Device for opening and closing the roof hatch of a vehicle
BACKGROUND OF THE INVENTION 
     The present invention relates to an opening and closing device according to the preamble of claim 1 for a roof hatch. 
     Roof hatches are primarily used in buses for ventilation and as emergency exits. The devices for opening and closing them must be easy to use, require as little space as possible, and, of course, be easy to install. 
     The known devices for opening and closing roof hatches are manually operated mechanical devices or remote-controlled pneumatic devices. Mechanical devices take a great deal of space and increase the total height of the vehicle. The tubes of pneumatic devices are inconvenient to install and therefore considerably increase the installation costs. 
     GB patent 1 350 844, for example, discloses a mechanical device in which the opening and closing movement of the roof hatch is effected by means of a lever system connected to a bar and by means of a vertical member articulated to the lever system and the hatch. The said vertical member increases the height of the construction in the closed position, and additionally it requires considerable special attachments to enable the vertical member and the roof hatch to move in relation to each other during the lifting and lowering movement of the roof hatch. Each corner of the roof hatch can be moved independently of the other corners, but only to the open position or the closed position, and not to any intermediate position. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a roof hatch opening and closing device which is of a maximally simple construction, takes as little space as possible, does not increase the height of the roof hatch construction, and can be opened steplessly in the horizontal direction or tilted forwards or backwards in the drive direction. 
     This is achieved with the opening and closing device according to the invention by giving it the characteristics according to claim 1. 
     The bar of the opening and closing device according to the preamble of claim 1 is thus, according to the invention, provided with a thread so that in one half of it, in the longitudinal direction, the thread is, for example, an S-shaped thread, and in the other half the thread is in the opposite direction. When the bar is rotated, the moving ends of the longer arms of both lever systems thus move in opposite directions over a distance which depends on the number of revolutions rotated by the bar. While the end secured movably to the bar moves along the bar, the opposite end, which is articulated to the roof hatch, is raised or lowered, thereby raising or lowering the roof hatch. Since each of the lever systems is made up of three arms of equal length, that end of the longer arm which is secured to the roof hatch moves in the vertical direction when the bar is rotated. Since, furthermore, the lever systems connected to the same bar are identical, but are installed as mirror images of each other, and the thread of the bar in each half longitudinally is identical, the corresponding side of the roof hatch remains horizontal throughout movement in the vertical direction. 
     To the roof edge surrounding the aperture in the roof there is preferably fixedly fitted two bars, one to the front side, in relation to the drive direction, and the other to the rear side. Both bars with their lever systems can be used independently of each other, and the corresponding sides of the roof hatch move respectively independently of each other. The roof hatch may have only one bar with its lever system, in which case only the side guided by it will be raised and lowered. 
     The rotating of the bars is preferably by an electric motor, which enables the bus driver, a passenger or anyone to adjust, open or close the roof hatch by pressing a button either in the dashboard of the bus or close to the hatch. The rotating of the bars may, of course, also be effected in some other manner, for example by manual cranking. 
     Since the opening and closing device is of plastic or some corresponding resilient material, it yields, if necessary, if one side is raised higher than the other. 
     The advantages of the opening and closing device according to the invention are obvious. Its construction is very simple, consisting of simple structural parts known per se. The device itself and the necessary electric wiring are easy to install. The device takes very little space and fits, for example, in a groove, covered by the hatch, between the roof aperture and the hatch. It can be adjusted steplessly. An emergency trigger is easy to install in it, on both the inside and the outside, or on only one side. The device may, for example, be fastened to the frame of the roof hatch by a dovetail joint secured by a cotter. In a case of emergency the cotter is removed, whereupon the joint can be undone by pushing the construction loose from the frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention is described below in greater detail in the form of a preferred embodiment of the invention, with reference to the accompanying figures, in which 
     FIG. 1 depicts a roof hatch with its opening and closing device, installed in the roof of a vehicle, as seen from the front and in the open position, 
     FIG. 2 depicts the same as FIG. 1, but as seen from the side and with only the front side of the hatch opened, 
     FIG. 3 depicts the same as FIG. 1, but with the hatch in the closed position, and 
     FIG. 4 depicts the opening and closing device in detail and with the roof hatch removed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the figures, the same parts are indicated with the same reference numerals. The roof hatch is indicated by numeral 1, the roof of the bus by 2, the electric motor of the opening and closing device by 3, the threaded bar by 4, the long arm of the toggle lever system by 5, and the short arm by 6. That end of the longer arm 5 which moves along the bar 4 is indicated by 5a and the end fastened to the roof hatch by 5b. That end of the shorter arm 6 which is fastened to the bar is indicated by 6b. Numeral 7 indicates the central pivot point of the lever system. 
     FIGS. 1-3 depict an opening and closing device according to the invention, fitted to a vehicle roof aperture and roof hatch, in different positions of the roof hatch. In FIG. 1 the hatch is in the open position, in FIG. 2 with only the front side raised, and in FIG. 3 the hatch is closed. One end of the shorter arm 6 of the toggle lever system is connected to pivot point 7 of the lever system between the ends of arm 5, and its other end is fastened stationarily, but pivotably, to pivot point 6b. The length of the shorter arm 6, which is articulated at pivot point 7 to the middle of the longer arm 5, is one-half of the length of the longer arm 5. The lower end of the longer arm 5 of the toggle lever system is connected movably to the bar at pivot point 5c and its upper end is connected pivotably to the roof hatch at point 5d. The distances of all the three pivot points 5c, 5d and 6b from the central pivot point 7 are equal. Owing to this, the line between pivot point 5d and pivot point 6b is always vertical. The threaded bar 4 comprises two halves being of a continuous structure which rotate uniformly. Since the thread of the threaded bar 4 is similar on both halves of the bar 4, the pitch being the same, but in opposite direction in relation to each other, the movements of the two lever systems are symmetrical and the moving front side and/or rear side of the hatch is horizontal. 
     The roof hatch is very easy to operate using the opening and closing device according to the invention. Both the front side and the rear side of the hatch have each an electric-motor control button, and the respective side can be raised or lowered by pressing the button. It is possible to raise only one side or both of them, independently of each other. The roof hatch may also have only one bar with its lever system, in which case the hatch can be opened only to a tilted position. 
     The opening and closing device according to the invention can, of course, vary in many ways within its protective scope. Instead of an electric motor, for example, it may be rotated manually.