The present invention relates to a slot valve of the kind comprising a valve hood and a valve damper which latter is surrounded by the hood, and a control means with a control knob for moving the valve between an open and a closed posit¬ ion. Slot valves are intended to open or close an air flow through narrow slots in the upper portion of a window frame. With the passage of time such valves received more or less complicated and successful designs, but it is a disadvantage of the previous known valves that the sliding surface areas of moving members are so small that wear may cause sloppy contact and, thus, leakage and undesirable draught. Another disadvantage may be complicated and time consuming mounting operations of several, possibly, small members which must fit together in a certain manner. Additionally, it may be time consuming reguire a number of operations to manufacture the separate members. It is, thus, an object of the. present in¬ vention to develop a sturdy and hard-wearing slot valve which is readily mounted. This is achieved by the fact that the control knob of the slot valve has a control means on the outside of the elongated valve hood. The size of bearing sur¬ faces is then only a question of design, and experience will show how large the faces must be for the materials selected for control knob and valve hood. The control knob has a void with an inwards open inclined groove on both sides of said void for guiding a tightening member which by movement of the control knob is moved in one or the other direction across the longitudinal direction of the slot valve, and thus, the valve damper of said slot valve is moved from a closed to an open position or vice versa.

By utilizing essential portions of the volume of the control knob, it is also possible to choose more freely as regards details for controlling the movement of said tensioning member, e.g. as regards dimensioning αuide grooves, coulisse means, and control pins, a design that is, indeed, made possible by the fact that the control knob fits on the outside of the

valve hood. In this manner it is possible to avoid the limitat¬ ions arising when larger or smaller portions of the control knob projects inside the valve hood to cooperate with, e.g. the edge of an aperture that was stamped out of the valve hood.

The invention is characterized by the features stated in the claims and it will be disclosed below with reference to the drawing, wherein

Figure 1 shows a portion of a slot valve with a control knob in an embodiment according to the invention shown in a side elevation, Figure 2 shows the same as Figure 1, but as seen from one end and with one end member removed, Figure 3 is -a side view of one half of a control knob at a larger scale, Figure 4 is a section through said control -knob along line IV,

IV in Figure 3 , arid Figures 5 and 6. show a tensioning member, as seen in a side view and an end view, respectively.

Figure 1 shows part of a valve hood 1 with a control knob 2. On both sides valve hood 1 has longitudinal grooves 3 , as clearly shown in Figure 2, and due to said grooves longitudinal projecting edges 4 are formed for cooperation with control knob 2 due to the fact that said control knob is provided with inwards opening grooves 5 at its lower end, as clearly shown in Figures 3 and 4. In this manner control knob wi ^" ll have steer¬ ing contact all over its length on the projecting edges 4, and its movement will be soft and comfortable, especially when the valve hood is an extruded aluminium member and the control knob consists of a suitable plastic material.

To be able to adjust valve damper 6 of the slot valve (Figure 2) control knob 2 is connected with the damper by the aid of a tightening member 7. Movement of control knob 2 in one direction along valve hood 1 in Figure 1 will cause tightening

member 7 to move downwards in Figure 2 , and cause damper 6 to move into contact with the window frame about the valve slot. Movement of the control knob in the opposite direction will cause tightening member 7 to move up into the knob to move valve damper 6 from the window frame and, thus, to open for an air flow through the slot. Said movement is achieved by the fact that control knob consists of two members 2, 2', in the shape of two halves fitting together. One half 2' is shown in Figure 3 and comprises a void 8 with an inclined groove opening towards said void. As will appear from Figure 2, tightening member 7 projects into said void and a control stud 10 (Figures 5 and 6) on each side of the tightening member projects into the mutually opposed grooves 9 in void 8. Grooves 9 are inclined and this will cause said movement of tightening member 7 and, thus, the damper 6 between an open and a closed position by moving control knob 2,2' . In Figure 3 the top end of tightening member 7. with a control stud 10 is shown in dotted lines to illustrate the mode of operation.

For locking the valve damper either in a closed position or in an open position groove 9 at each end goes over into a straight portion 11 which will bar movement of control stud 10 across the longitudinal direction of the slot valve.

Damper 6 may also have an undercut groove for receiving the edge 12 of a foot 13 at the lower end of tightening member, whereas the remaining tightening member projects upwards through the valve hood in an aperture stamped out to this end.

Halves 2,2' of the control knob may be assembled in any suit¬ able manner, e.g. by the aid of apertures in one half and pins on the other for mutual engagement, but there are other possibilities as well, and that goes for the attachment of tightening member 7 on the damper 6 as well. Such attachment may obviously be achieved in another manner than shown.