Known combustion air feeding i. e. draught regulation arrange- ments usually comprise arrangements having aligning combustion air apertures arranged in superimposed discs or the like. Said superimposed discs having a flat or other shape can be moved in mutual relationship so that the alignment of said apertures can be changed, and thus the amount of combustion air flowing through said apertures can be controlled.

The most essential drawback in such regulating arrangements is the fact that the total effective opening constituted by the sum of the apertures, in order to facilitate also a completely closed mode for said apertures, still must be less than 50 percent of the available area even when the regulation opening is open to a maximum. Such structures also have the usual drawback of a certain play, due to which the passage of air through the structure cannot be totally shut off. Such struc- tures comprising multiple openings like holes or slits always also induce air turbulence and hence guiding of the air is complicated to manage. If, e. g., an air scavenging is to be achieved on the hatch's glass by means of such a structure one must, in a prior art arrangement, construct a vertical array of holes to feed the air, wherein the air, on the other hand, will have a twisted flow which renders the management of the air streams and of the combustion process more difficult.

Flap structures arranged for the regulation of air feed are also known, wherein a flap is arranged in an open channel, which flap closes off said channel. One essential drawback in such a structure is the large space needed for such an open channel, due to which such structures are badly suited for use, e. g., in oven hatches or the like structures having an essentially flat shape, and where there is very little space available for the air flow control arrangements.

One object of the present invention is to dispose of the draw- backs described above. According to the present invention this object is achieved as disclosed in the appended claims. Thus, the arrangement according to the present invention is charac- terized in that it comprises a closing element extending in an air slit essentially in the direction of a surface structure, said element being pivotable around it's longitudinal axis and comprising a suitably oblong channel extending through the element. The method according to the present invention is characterized by forming opposite air slit portions at two corresponding edges of a frame, for co-operation with a closing element extending essentially in the direction of said edges, and arranging a closing element to be pivotable around a rotational axis directed in the direction of said edges, said closing element comprising at least one radial slit ex- tending through said element in the direction of the air slit.

An oven hatch in accordance with the present invention is characterized in that it comprises an air slit extending es- sentially in the direction of the edge of a frame of said hatch, a closing element being arranged in said air slit and comprising a radial aperture, wherein said closing element is pivotable around an axis extending in the longitudinal di- rection of said air slit.

The invention will now be described in more detail with refe- rence to a favorable embodiment which is disclosed in the appended drawings, wherein Figure 1 discloses a general view of a half of a closing ele- ment in accordance with the present invention, seen in a through-going direction, Figure 2 discloses a section of the half of the element ac- cording to Figure 1, seen in a closing direction, Figure 3 discloses a section of the hatch frame, to which a closing element in accordance with the present in- vention is arranged, wherein said element is shown in it's open position, Figure 4, in the manner of Figure 3, discloses a section of said hatch frame at the location of a guide pin for said closing element, Figure 5 discloses a complete section of an oven hatch struc- ture according to one embodiment of the present in- vention, Figure 6 discloses a fastening element for said closing ele- ment in accordance with one favorable embodiment of the present invention, Figure 7 discloses a section of the fastening element ac- cording to Figure 6, and Figure 8 discloses a section of the hatch door frame at a point located outside the closing element, wherein the end of the closing element and a fastener for said element can be seen.

Referring to Figure 1 a closing element 1 according to the present invention is favorably constituted of an oblong es- sentially cylindrical rotational body 2, through which an air channel 3 extends, said air channel also being oblong and extending in the direction of the rotational axis of said rotational body 2. Favorably said channel 3 extends through said closing element 1 as separate portions 3,3a so that suitably relatively narrow guiding collars 4,4a having a full cylindrical shape remain between said portions and at the end of the element, as best can be seen in Figure 2.

Referring to Figure 3 the closing element 1 according to the present invention is suitably arranged at a frame 5 of a hatch door, favorably between said hatch door frame 5 and an im- muration or masonry frame 6 so that said closing element 1 fills up a space between said hatch door frame 5 and said immuration frame 6, said space simultaneously constituting an air slit 7 connecting the inner space of the oven with the outside. Especially favorably the air regulating arrangement with its closing element 1 at this point also constitutes a part of a sealing arrangement between the hatch door and said immuration frame 6.

Figure 3 discloses how said air channel 3 in accordance with a favorable embodiment of the present invention extends in said air slit 7 between said hatch frame 5 and said immuration frame 6 when the closing element is in a position"fully open". In a position"fully closed"said closing element is turned about 90°, by means of an operating pin 12 disclosed, e. g., in Figure 4, whereby intact portions 8 of said closing element 1 essentially totally prevent air from flowing through said air slit 7 from the outside into the oven. Thus, the closing ability of the structure according to the present invention is established by an axial pivoting of an essential- ly cylindrical guiding means and therefore the structure does not need any prior art counter piece, which until now has been inevitable in connection with the use of arrays of holes.

Thus, a structure according to the present invention renders possible a significantly larger amount of air compared to a prior art opening of the same size and especially in relation to its length. On the other hand, the use of a counter piece might be motivated in some embodiments of the present in- vention, especially so that a special directional air guidance may be achieved thereby.

Suitably, said closing element 1 is freely pivotable between said two positions. Said air slit 7 is favorably arranged so that the air stream flows into the oven at least partially in the direction of a glass 9 which may be arranged in the oven hatch door and along the surface of said glass. The air flow is then, due to the structure of the arrangement according to the invention, essentially straight without any bends, whereby the air flow remains consistent and the glass remains clean and relatively cool. According to another embodiment the air slit may be directed straight into the interior space of the oven, whereby, e. g., an especially effective horizontal flow into the embers can be achieved.

According to one embodiment (not shown) of the present in- vention a second air slit is also arranged through the hatch door frame 5 so that the flow of air can be guided also in other ways, whereby several"extreme positions"for the closing element also are possible. According to another embodi- ment (not disclosed) said closing element 1 is arranged wholly in an air slit arranged within the oven hatch frame structure 5. In case of solid glassless doors said air slit or air slits 7,7a, 7b and their closing elements 4a in accordance with the invention may also be arranged, e. g., centrally in the door.

Said closing element 1 suitably comprises one or several sur- face portions 11, lla of said intact portion 8, which surface portions co-operate with a corresponding sealing element 10, 10a arranged at said air slit 7, favorably so that one of said surface portions 11 co-operates with a sealing 10 located at the hatch door or at its frame 5b, and the other surface portion lla co-operates with a sealing 10a at said immuration frame 6, whereby said air slit 7 suitably is formed there- between.

In practice, machined sliding surfaces are favorably made in said air slit portions 5 and 6 for the closing element's 1 guiding collars 4,4a, and sealing portions 10,10a extending in the direction of the edge of the frame are arranged at least at the intermediate portions thereof so that said sealing portions 10,10a from opposite directions co-operate with the sealing surfaces 11, lla of a closing element 1 ar- ranged therebetween.

Further, an oven hatch according to the present invention is favorably arranged so that there is at least two air slots 7 provided with closing elements 1 and extending in the di- rection of the edge of the door frame, favorably so that one 7 of said air slits and its closing element 1 is located at the upper edge of the door and the other air slit 7a and its closing element la correspondingly is arranged at the lower edge of the door, as disclosed in Figure 5. Since the main extent of a regulation arrangement in accordance with the present invention is in one direction only, the arrangement can be utilized clearly more freely, compared to prior art, e. g., so that air slits 7 are freely arranged at such positions at the oven structure where an air feed is ap- propriate with respect to the combustion and to the oven's other properties. Thus, one individual hatch door may also comprise several air slits 7 having adjustable closing ele- ments 4a.

According to one favorable embodiment of the present invention said closing element 1 is attached to the hatch door frame 5 by means of a fastening element 15 comprising an essentially half-arched portion 13 and a suitably two-part clamping edge 14,14a. Herein said half-arched portion 13 aligns the closing element 1 and keeps it against the door frame 5, while said clamping edges 14,14a simultaneously press the door's one or more glass portions 9 against said frame 5. Suitably, said fastening element 15 is manufactured of a relatively thin sheet metal or the like material, whereby the fastening ele- ment 15 provides a certain flexibility against thermal ex- pansion of the door frame 5. Simultaneously, said fastening element 15 suitably forms a casing which is sealed against the draught control arrangement i. e. against said closing element 1. Said casing controls the axial pivoting movement of the closing element and keeps its end sealing in place. In an arrangement comprising at least two separate glass portions (not shown) said fastening element 15 is favorably attached at such a location at the hatch door frame 5 that one and the same fastening element retains both glass portions in place. A general manner for attaching said fastening element 15, favorably with only one screw, is especially disclosed in Figure 8, which also discloses that the door frame 5 at a portion not comprising a closing element 1 in accordance with the present invention will be positioned directly against the sealing 10a arranged in the immuration frame favorably by means of a special edge rib 16. A fastener effected in this manner is rapid and easy to attach and simultaneously it saves operative steps at the assembling.

Even though the present invention has been described above mainly with reference to such an oven structure wherein the closing element is located between an immuration frame and a hatch door frame it is clear that the general arrangement according to the present invention also can be utilized in door structures so that an air slit and its closing element is located only in the door, only in the immuration frame, in both of them and/or between them. Further, the location of such closable air slits is not restricted only to the center of a door, but such slits can also be located, e. g., at both horizontal portions of an angled door, and in certain cases also at vertical portions. An air control arrangement ac- cording to the present invention can also be accomplished as a structure which is separate from the hatch door structure and arranged at a suitable location in the vicinity of the door or totally apart therefrom.

Above some favorable embodiments of the present invention have been disclosed, but for the expert in this field it is clear that the invention can be modified in many other ways within the scope of the appended claims.