Traditionally, in known oven hatch structures manufactured from cast iron or the like material, the hinging is arranged individually for each hatch in an integral manner so that the hinge comprises a hinge pin, for which a counter surface is made in the cast by means of drilling. In practice, however, drilling in cast iron tends to cause problems in such a res- pect that a certain inexactness usually appears, which ac- cording to prior art will be transferred as such to the hinge structure. Thus, a certain error usually will build up re- garding the mutual position of the parts, which error makes the assembling of the parts more difficult and has a negative impact on the hinge's function. In practice, the quality of such a product is rather irregular, which cannot be accepte.

According to modern standardization oven hatch doors should be self-closing. This can be achieved i. a. so that a spring is integrated in the hinge structures, by means of which the hatch is forced to move into a shut position. In this respect another problem resides in the prior art therein that the adjustment of the closing springs adapted to such hinge struc- tures is rather difficult and, in practice, sometimes im- possible.

Another drawback related to a prior art hinge. structure inte- grated as such in castings is that it usually permits the use of only one kind of arrangement, in which case an alteration of the hinge type always also requires corresponding alterations in the castings. Thus, alternative hinge structure arrangements also require alternative castings, which i. a. increases the number of molds.

The present inventive arrangement has been developed in order to solve these problems related to known oven hatch struc- tures. The characteristics of the arrangement are evident from the appended claims. Thus the oven hatch arrangement according to the present invention is characterized in that said body part and said pin part constitute a separate hinge element comprising at least two mutually pivotable portions, each of said portions, respectively, connecting by means of adjoining surfaces to corresponding adjoining surfaces formed in said castings or the like pieces to be connected. The inventive method is characterized by providing in a hinge element and in said castings, correspondingly, mutually essentially congruent adjoining surfaces which extend essentially in the direction of the hinge axis, wherein the mutually pivotable parts of the hinge element are attached to the corresponding hatch struc- ture portions by means of transverse elements which extend through said adjoining surfaces.

The invention will now be described in more detail with refe- rence to a favorable embodiment disclosed in the appended drawings, wherein Figure 1 partly in section discloses the hinge side of an oven door, seen from the end of said door, Figure 2 discloses the structure according to Figure 1 in a section through A-A, Figure 3, correspondingly, discloses the structure according to Figure 1 in a section through B-B, Figure 4, correspondingly, discloses the structure according to Figure 1 in a section through C-C, Figure 5 partly in section discloses an hinge structure ac- cording to a favorable embodiment of the invention, and Figures 6a to 6d disclose parts of the hinge structure ac- cording to Figure 5.

According to Fig. 1, an oven hatch structure generally indi- cated by the reference 1 comprises an actual hatch door 3 usually made of cast iron or the like material, which hatch door most often is pivotally attached to an immuration or masonry frame 2 or the like structure made of a corresponding material or another material and attached in an essentially fixed manner to the oven (not shown). Said hatch door 3 is connected, by means of a hinge having the general reference 4, to said immuration frame 2 or the like so that said hatch door 3 can be pivoted, around a pivot axis D-D defined by hinge pins 5,5', in relation to said immuration frame 2.

According to the invention the hinge arrangement 4 comprises, in distinction to prior art in this field, a separate hinge element 4a of which one embodiment best can be seen in Fig. 5.

According to the invention said hinge element comprises suitably separately manufactured external adjoining surfaces 6,6a, 6b which interact with adjoining surfaces 7,7a manu- factured in said immuration frame 2 and said door 3, res- pectively, as can be seen in more detail in Figs. 2 and 3.

Correspondingly, Fig. 4 discloses a section of a special struc- ture wherein said hinge elements 4a are used also for at- taching a separate cover piece, i. e. a side piece 8, from the back side by means of said adjoining surfaces 6b and 7b, res- pectively, which piece covers said hinges, so that the actual hinge element 4a remains hidden behind said side piece 8.

According to one favorable embodiment of the invention said adjoining surfaces 6,6a, 6b, 7,7a and 7b extend at least partially in the direction of said axis D-D of said hinge element 4a. In this case a part 9 or 10, respectively, of said hinge element 4a is attached, by means of transverse elements 11 extending through said element 4a, to said immuration frame 2, and a second part 10 or 9, respectively, is attached in a corresponding manner to the door portion 3, favorably so that said transverse elements 11 extend essentially perpendicularly in relation to said adjoining surfaces 6,6a, 6b, 7,7a, 7b.

Said transverse elements 11 are favorably bolts or the like attachment elements known per se, which suitably extend through holes 12,12a, 12b extending through the hinge element 4a. Said bolts 11 or the like are attached to corresponding holes 13 made in the cast iron pieces 2,3 and 8, said holes suitably comprising a threading or the like.

Thus, said transverse elements 11 will press together said adjoining surfaces 6,7; 6a, 7a and 6b, 7b, respectively, of said hinge piece 4a and said castings 2,3 and 8. Thus, the mutual alignment of said hinge element 4a and said castings 2, 3,8 has been shifted from being an axial alignment to being a transverse alignment, with respect to said axis D-D, wherein the management of any possible inexactnesses is considerably easier. If the quality level of the casting is reasonable and the surface of the hinge element, correspondingly, is reasonably even, the hinge element 4a can be attached to the casting 2,3,8 or the like without any other finishing or machining operations than the forming and adapting of said holes 13 for said transverse elements 11. In this manner the invention saves a considerable amount of work. Generally the required precision level for the adjoining surfaces is ob- tained already in connection with a casting process having an ordinary level of quality. Correspondingly, the evenness of the outer surface of the hinge element usually is sufficient if the element is manufactured of e. g. a drawn rod material of a suitable dimension.

In relation to a usual known hinge structure the general ex- tent of the present fitting still remains in the axial di- rection, but its actual functional direction is, in difference to prior art, transversal in relation to the axis. In this manner the influence of drilling errors or the like related to a usual hinge can, in practice, be eliminated using adjoining surfaces in the casting, which surfaces simply are pressed against each other by said transverse elements 11, such as bolts or the like. At the same time a structure has been achieved, wherein the assembling is considerably easier, in relation to prior art, since the precision requirements set by the fitting are lower.

In a corresponding manner the surfaces of the hinge element can be left unmachined, if the evenness of the element's outer surface is sufficient. This can be achieved, as discussed above, e. g. so that as the material for the manufacturing is chosen a material having such dimensional and surface quality properties which render a separate machining generally un- necessary. In the favorable embodiment disclosed in the drawings said hinge element 4a constitutes an essentially cylindrical piece, the adjoining surfaces 6,6a, 6b of which connect to lateral adjoining surfaces 7,7a, 7b formed in the casting of said immuration frame 2 and said hatch door struc- ture 3, respectively.

If necessary, one or both of the opposite adjoining surfaces 6,7; 6a, 7a; 6b, 7b, and usually especially the adjoining surfaces 7,7a, 7b made in said castings 2,3 and 8 can further be separately machined, whereby this additional treat- ment provides an adjoining surface, which has a sufficiently even surface. Correspondingly, the hinge element's 4a adjoining surfaces can further be separately machined. Thereby the surfaces 6,7; 6a, 7a; 6b, 7b which will be arranged towards each other, will have shapes whose range of ex- tensional variation is restricted, i. e. their relatively exact mutual extension hardly varies, at least at that point where the surfaces are arranged face to face.

In a hinge arrangement arranged to be integral with the castings, according to prior art, said castings are, in prac- tice, usually connected to each other so that they cannot be replaced, at least not with castings of another type. Thus, forming different variations requires a large number of dif- ferent molds as well as the manufacturing and storage of a large number of different castings. Compared to this, a hinge element 4a and, correspondingly, the castings 2,3 and 8 con- nectable thereto in accordance with the present invention are of a modular structure having a good mutual interchangeability between the parts. Thus, the adaptation of a specific hinge type to different door assemblies and, correspondingly, ex- changing the hinge type in accordance, e. g., with the require- ments on different markets is easy to perform without any complicated modifications in the actual castings.

In an arrangement according to the present invention the hinge element 4a is also easily replaced, e. g., in case of a pos- sible breakdown or, for example, if a more sophisticated hinge has been introduced on the market. Correspondingly, the same hinge element 4a can be used in different hatch structures, and in the same structure individual parts, such as doors 3, frames 2 etc. can be exchanged. According to a preferred em- bodiment the general dimensions of said hinges 4,4a and the hatch lock mechanisms, and especially the shape of their ad- joining surfaces 6,6a, 6b are arranged to be essentially identical, whereby these parts too, and thus also the handed- ness and/or the mounting direction of the hatch door 3 can be exchanged by mutually interchanging the hinge elements 4a and the locking. In the same way a hinge element of the same type can be used in connection with many different types of hatch structures, and the hinge structure can be developed ir- respectively of the hatch structures.

A favorable hinge element structure is accomplished in the manner disclosed in more detail in Figures 6a to 6d so that there further is a spring assembly 16 arranged in the hinge element 4a between the pin part 14 thereof and the body part 15 connected thereto. Due to the spring assembly the hinge element is inherently urged into a specific position, i. e. so as to press the hatch door 3 against said immuration frame 2, i. e. into a closed position. Said spring assembly 16 comprises an adjustment bushing 17 (Fig. 6b) to which tension suitably can be applied and which affects the mutual pivoting positions of said body part 15, said pin part 14 and said closing spring 18 arranged therebetween (Fig 6c) around the hinge element's 4a pivotal axis, i. e. around said pin 5. This structure is favorably formed of three machined parts and a spring, and it permits a stepless adjustment of said spring 18 as well as a releasing of said spring 18 or totally omitting the spring.

Said adjustment bushing 17 is preferably lockable in relation to said pin part 14, the opposite end of said closing spring 18 being arranged in said body part 15 in a torsionally stiff manner. Alternatively, said adjustment bushing 17 is lockable in relation to said body part 15, whereby the opposite end of said closing spring 18 is arranged in a torsionally stiff manner at said pin part 14. In the embodiment disclosed in the Figures said pin part 14 can be locked, by means of said trans- verse elements 11 and via said adjoining surfaces 6, to said adjoining surfaces 7 at said immuration frame 2. Corresponding- ly, said body part 15 of the hinge element 4a will be locked, at it's adjoining surfaces 6a, to the adjoining surfaces 7a at the door 3, and thus said spring 18, in practice, will function between said body part 15 attached to the door 3 and said pin part attached to the immuration frame 2, and close the door 3. A second hole 12a in the body part 15 of the hinge makes it possible, on the other hand, to attach said side piece 8 in an easy manner to be movable along with the door 3.

Even though mainly such embodiments have been discussed above, wherein both the oven hatch door and the immuration frame rather are made as castings, it is clear that a corresponding arrangement can be utilized also in connection with pieces made of another material such as, e. g., sheet metal. It is also clear that one of the pieces, e. g., said oven hatch door may be made of cast iron while the immuration frame can be of another material. The arrangement can also be adapted in such structures wherein there is no actual immuration frame, but where the oven hatch door is connected directly, e. g., to the structure of a ready made oven hearth structure or, e. g., to an oven front surface cast of a mass material. In such a case a hinge element provided with respective transverse elements can be attached also, e. g., directly into the casting.

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.