VIEWING WINDOWS, ESPECIALLY FOR HVAC SYSTEMS

Description

[0001] The present invention relates to a viewing window for installation in a viewing opening, in particular in a viewing opening of an air handling unit (AHU), with two spacer frames that can be inserted into the viewing opening from opposite directions and whose end faces abut each other.

[0002] Such viewing windows for installation in viewing openings are known in various forms from the prior art. As a rule, these viewing windows have a two-part structure with one window section inserted into the viewing opening from one side and another window section inserted into the viewing opening from the other side, which are secured in the viewing opening in different ways.

[0003] From EP 3 375 968 A1, for example, a viewing window with two window sections is known. These sections are inserted into the viewing opening from opposite directions and mounted in the opening by screwing them together. The two window sections have appropriately designed screw sections that allow for some compensation of wall thickness, thus enabling the use of these viewing windows even with walls of varying thicknesses. The screw sections extend into the interior of the viewing opening and form a collar covering the inner circumference. Therefore, they serve not only to connect the two window sections but also to prevent any soiling, particularly from insulating material used inside the wall, from entering the viewing window.

[0004] A similar viewing window is known from US Patent 4,525,961 A, in which the two window elements are also inserted into the viewing opening from different directions and connected to each other via a snap-fit ​​mechanism. This snap-fit ​​mechanism also allows for a certain degree of compensation for wall thickness and is arranged on a collar that covers the inner circumference of the viewing opening, thus protecting the interior of this viewing window from contamination from within the wall.

[0005] Furthermore, viewing windows are also known which have a simpler design, adapted to a specific wall thickness, and can be attached to the viewing opening using additional fastening elements, such as screw bolts. To protect the interior of these viewing windows from contamination from within the wall, the window elements inserted into the viewing opening from both sides have a spacer frame inserted into the opening. In the installed position, the end faces of the spacer frames of the two window elements rest against each other, thus also preventing the ingress of contaminants into the interior of the viewing window.

[0006] Although the viewing windows described above have proven their worth and offer reliable protection against penetrating contaminants, in certain applications, fogging may occur due to changing air conditions, moisture present in the wall filler, or similar factors. This can impair visibility.

[0007] To avoid this problem, viewing windows are also known that have two end-faced spacer frames which can be inserted from opposite directions, with the seal being ensured by a circumferential end seal. Examples of this are disclosed in WO2004009943 A1 and US2019055774 A1.

[0008] TaskThe purpose of the present invention is to provide a viewing window in which the risk of impairment of visibility is reduced even under unfavorable conditions and which offers manufacturing advantages.

[0009] This task is accomplished with a viewing window of the type mentioned above by solved that an end seal is provided on the end faces for mutual sealing of the two adjacent spacer frames.

[0010] The end seals on the front faces create an airtight seal between the interior of the viewing window and the outside. This significantly reduces the risk of moisture ingress, for example, due to residual moisture in the filler material from the wall's manufacturing process, and the associated risk of condensation on the viewing window. The risk of impaired visibility is therefore considerably reduced, even under unfavorable conditions.

[0011] Advantageous designs and further developments are the subject of the dependently formulated subclaims.

[0012] According to the invention, the end seals are designed as sealing halves and arranged such that the end seals of the two adjacent spacer frames form a continuous, circumferential seal. In this way, two spacer frames, each having only one sealing half, can be used, the sealing halves of which together form a fully circumferential seal when installed. The end seals and their arrangement can be identical on both spacer frames.

[0013] In this context, it is also a constructive advantage if the end seals extend over half the circumference of the spacer frame.

[0014] Another advantageous embodiment provides that the spacer frames have a substantially rectangular, particularly square, shape, and the end seals are substantially U-shaped. A substantially rectangular or substantially square shape is understood to mean rectangles or squares whose corners are rounded with a certain radius. In such spacer frames, the end seals can be substantially U-shaped. The U-shaped end seals can extend over approximately half of the end face.

[0015] In this context, a further advantageous embodiment provides that the end seals extend along one side of the spacer frame to the midpoint of two adjacent sides of the spacer frame, or by a predetermined amount beyond this point. Essentially, to form a complete circumferential seal, it is sufficient if the two end seals extend to the midpoint of two adjacent sides of the spacer frame. In this case, the seals are butted together in the center when assembled. To improve the sealing properties, it may also be advantageous for the end seals to extend beyond the center by a predetermined amount, for example, 1 mm to 5 mm. In the assembled state, the end seals are then not butted together, but rather have a certain overlap.

[0016] Alternatively, the end seals could extend along two sides of the spacer frame to two corners of the spacer frame, or by a predetermined amount beyond. In this case, the seals would be butted together at the corners when installed, or there would be a certain overlap.

[0017] An advantageous design for achieving a reliable sealing effect provides that the end faces of the spacer frames have a groove for receiving the end seal. The end seal can be reliably positioned in the groove and / or sufficient compression of the end seal can be ensured.

[0018] A particularly advantageous embodiment in this context provides that the arrangement and length of the groove on the end face are adapted to the arrangement and length of the end seal in such a way that a groove is provided only in the area of ​​the end seal, and the remaining areas of the end face are without a groove. In the assembled state, the groove-free areas of the end face can form a counter-sealing surface for contact with the end seal of the opposing spacer frame. This also contributes to a reliable sealing effect.

[0019] A particularly advantageous design from a manufacturing and assembly perspective involves the end seal being integrally bonded to the end face. This one-sided connection of the end seal is especially easy to assemble, as the end seal does not need to be mounted as a separate part. The end seal can, for example, be injection-molded onto the end face using a two-component injection molding process. Alternatively, the end seal can be foamed onto the end face. The end seal can be made of polyurethane (PUR) foam.

[0020] To cover the interior of the wall and protect it from internal contaminants, the spacer frame can have a circumferential collar to conceal the inner edge of the viewing window. This collar prevents filler particles from penetrating the interior of the window. The collar can be made of an opaque material. This can offer aesthetic advantages, as the filler material inside the wall is not visible from the outside through the viewing window or its spacer frame. The depth of both collars can correspond to the thickness of the wall containing the viewing window. The depth of the individual collars on both spacer frames can be identical or different. For example, to cover the interior of a 40 mm thick wall with the collars, the collars on both spacer frames could have a depth of 20 mm.Alternatively, it could be provided, for example, that one of the two frames has a depth of 10 mm and the other of the two frames has a depth of 30 mm.

[0021] Another advantageous embodiment provides that the spacer frames have several spacers distributed around their circumference. The spacers ensure precise mounting within the viewing opening, and their size can be adapted to the wall thickness.

[0022] In this context, an advantageous embodiment further provides that the spacers are designed and arranged in such a way that the spacers of the two spacer frames are in contact with each other.

[0023] In this context, it is also advantageous if the spacers are designed like connectors, with one group of spacers being male and the other female. The two spacer frames can then be plugged together using these spacers. This can offer manufacturing advantages. For example, the manufacturer of an air handling unit could insert the spacer frames into the inspection opening during the production of the unit housing and connect them using the spacers. The interior of the housing wall can then be filled, for example, by injecting a suitable foam. The spacer frames prevent the foam from entering the inspection opening area.

[0024] A particularly advantageous embodiment provides that the two spacer frames are either identical or differ in the depth of their bezels. This keeps manufacturing costs low, as only one tool is required for producing spacer frames that are identical. If the spacer frames differ in bezel depth, a single tool can also be used for their production, featuring a die insert that accommodates the different bezel depths. Bezel depths of 15 mm, 20 mm, and 30 mm have proven advantageous. However, other depths can also be provided and easily produced using a corresponding die insert.

[0025] Another advantageous embodiment provides that a glazing support carrying a viewing window is arranged on each of the spacer frames. The glazing support can be integrally molded onto the spacer frame. Alternatively, the glazing supports can be designed as separate components and connected to the spacer frames. In this case, an intermediate seal can advantageously be provided between the glazing support and the spacer frame, which also prevents moisture from penetrating the interior of the viewing window. The intermediate seal can be designed as a separate component, for example, as a sealing cord or O-ring seal. It is particularly advantageous for the intermediate seal to be integrally molded onto either the spacer frame or the glazing support. For this purpose, the intermediate seal can be injection-molded onto the end face of the spacer frame or the glazing support using a two-component injection molding process.The intermediate seal can also be foamed in place. In this case, the intermediate seal can be made of polyurethane foam. The spacer frame or the glazing carrier can have a groove to accommodate the intermediate seal.

[0026] The glazing units can also have an outer seal to seal them against the wall containing the viewing window. The intermediate seal can be a separate component, for example, a sealing cord or O-ring seal. The outer seal can seal the edge of the viewing window. The outer seal can extend around the entire circumference of the viewing window. Advantageously, the outer seal can also be formed integrally with the glazing unit. In this case, the outer seal can be manufactured together with the glazing unit using a two-component injection molding process or foamed onto it. The outer seal can, in particular, consist of polyurethane foam. The glazing unit can have a groove to accommodate the outer seal.

[0027] In a further advantageous embodiment of the invention, the two spacer frames and the two glazing supports can be detachably attached to the viewing opening by means of fasteners. It is not necessary to attach the spacer frames and the glazing supports separately. Rather, the spacer frames and the glazing supports can be detachably attached to the viewing opening by means of common fasteners. The fasteners can, in particular, be designed such that each spacer frame and each glazing support can be clamped against the wall from opposite sides of the viewing opening.

[0028] In this context, it is particularly advantageous if the fasteners are designed as screws, with one of the washer carriers having through-holes and the other with screw-in holes, which can be designed as screw bosses, to accommodate the fasteners. The use of screws allows for a simple and reliable connection. The end gasket can also be compressed over the screws to achieve the desired sealing effect.

[0029] Another advantageous embodiment provides that some, preferably all, of the fasteners extend through the spacers. When the screws are tightened, the spacers ensure a defined connection. This avoids the risk of bending parts of the viewing window or the wall due to overtightened screws.

[0030] It is further proposed that the disc carrier be fitted with a cover concealing the fasteners. This would also achieve an aesthetically pleasing appearance in the area of ​​the screw heads, concealing them completely. The cover could be attached to the disc carrier without tools, particularly via a snap-fit ​​connection.

[0031] To allow a view through the viewing window of, for example, a machine or system located inside an air handling unit, even under poorly lit conditions, the viewing window may also be equipped with a light source. This light source could, in particular, be an LED element.

[0032] An advantageous embodiment in this context provides that the spacer frames have a lamp holder for the lamp. The lamp can be arranged in a replaceable manner within the lamp holder. In the case of a wirelessly operated lamp, a battery can also be arranged in a replaceable manner within the lamp holder.

[0033] Finally, it is proposed that the lamp holder be located radially outside the end seals, thereby reducing the risk of moisture or dirt entering the lamp area.

[0034] Further details and advantages of the invention are explained below with reference to the accompanying drawings of two exemplary embodiments. These show: Fig. 1 a perspective view of a first embodiment of a viewing window, Fig. 2 an exploded view of the viewing window made of Fig. 1, Fig. 3 an enlarged view of one of the in Fig. 2 The distance frame shown in Fig. 4 is a perspective section view through the viewing window. Fig. 1 , Fig. 5 one of the representations in Fig. 4 corresponding view of the viewing window in a position inserted into a viewing opening, Fig. 6 one of the view in Fig. 5 corresponding side view, Fig. 7 a perspective view of a second embodiment of a viewing window and Fig. 8 an exploded view of the viewing window made of Fig. 7 .

[0035] Fig. 1 shows in perspective view a viewing window 1 for insertion into a viewing opening 101 in a wall 100, see also Fig. 6 The viewing window 1 has an essentially square shape with rounded corners, but could also have a rectangular geometry or a round shape in the style of a porthole.

[0036] The viewing window 1 can be used, in particular in industrial plants, such as air handling units or climate control enclosures, for observing a machine, system, display, etc. located inside them, for example in a wall or a door of the corresponding systems, which are provided with a viewing opening 101 for receiving the viewing window 1.

[0037] How the representation in Fig. 2 As can be clearly seen, the viewing window 1 is constructed from a multitude of individual components. In the central area, the viewing window 1 has two spacer frames 2, which partially project into the interior of the viewing opening 101 and on whose outer sides two pane supports 10, 11, which support the actual viewing pane 9, are arranged. At the in Fig. 2 A cover 13 is also arranged on the left disc carrier 10.

[0038] Essential elements of the viewing window 1 are the two spacer frames 2. In this embodiment, the spacer frames 2 are made of plastic and manufactured using an injection molding process. In this embodiment, the two spacer frames 2 are identical parts and are mounted from opposite directions R1, R2 in the viewing opening 101 of the wall 100. In the mounted position within the viewing opening 101, the two spacer frames 2 are butted together end-to-end.

[0039] The distance frames 2 show, according to the representation in Fig. 3Each of the spacer frames 2 has a glare collar 6 extending around its entire circumference. The glare collar 6 is shaped like a hollow cylinder. The glare collar 6 extends axially from a connection area 18, to which one of the lens supports 10, 11 can optionally be attached, into the interior of the viewing opening 101. The plane of the connection area 18, which extends parallel to the plane of the viewing lens 9, forms a right angle with the glare collar 6.

[0040] At the free end of the visor collar 6, it has a front face 3 against which the opposite spacer frame 2 abuts with its front face 3, see also Fig. 4This results in an arrangement of the two end-to-end baffle collars 6 covering the inside of the viewing opening 101, thereby preventing the entry of contaminants originating from the interior of the wall 100, for example due to a mineral filler 102, into the interior of the viewing window 1; see also the illustration in Fig. 6 . The glare collars 6 are made of an optically opaque material, so that it is not possible to look through the viewing window 1 into the interior of the wall 100.

[0041] In addition to the glare collar 6, the spacer frame 2 has a plurality of spacers 7, 8 which lie against each other in the mounted position, see also the illustration in Fig. 1In the assembled position, the spacers 7, 8 are supported against each other in a pressure-resistant manner. The spacers 7, 8 are arranged radially outside the glare collar 6, so that in the assembled position they are located between the glare collar 6 and the inside of the viewing opening 101.

[0042] The spacers 7, 8 are designed in the manner of connectors and have a through-opening for the insertion of fastening elements 12. The through-opening extends centrally to the axis of the spacers 7, 8. A first group of the spacers 7 is designed in the manner of a male connector, a second group of spacers 8 in the manner of a female connector, as shown in the illustration. Fig. 7 They can be inserted into each other in a form-fitting manner. The spacer frames 2 can therefore be connected to each other using the spacers 7, 8.

[0043] In the axial direction, the spacers 7, 8 terminate at the level of the end face 3 of the baffle collar 6 such that the spacers 7, 8 are inserted into one another when the end faces 3 of the spacer frames 2 are in contact. The opposite end of the spacers 7, 8 terminates at the connecting area 18, which extends transversely to the spacers 7, 8.

[0044] To protect the interior of the viewing window 1 not only from contaminants but also from moisture, which may originate, for example, from the filler 102, an end seal 4 is provided in the area of ​​the end faces 3 of the glare collar 6. The end seals 4 are arranged such that the interior of the viewing window 1 is airtight in the assembled position.

[0045] The end seals 4 do not extend over the entire circumference of the end face 3, but only over half of the end face 3. In the exemplary embodiment, the end seal 4 extends along one side 6.1 of the flashing collar 6 to the midpoint of the two adjacent sides 6.2, 6.4. Due to this arrangement and design of the end seal 4, a continuous seal is formed when the spacer frames 2 are abutting each other, composed of the two end seals 4. To improve the sealing properties, it can also be provided that the two end seals 4 do not end exactly at the midpoint of sides 6.2, 6.4, but cover a predetermined amount further to provide a certain overlap.

[0046] How the representation in Fig. 3As can be further seen, the end face 3 has a groove 5 in the area of ​​the end seal 4, the length and arrangement of which are adapted to the end seal 4. The groove 5 can have an angular, in particular a square, or a rounded, in particular semi-circular or partial circular, cross-section.

[0047] The areas of the end face 3 without a seal do not have a groove 5. In the assembled position, an end seal 4 and an area of ​​the end face 3 without a seal are opposite each other, thus creating a good sealing effect.

[0048] The disc carriers 10, 11 are arranged on the outer sides of the spacer frames 2 in their connection areas 18.

[0049] An intermediate seal 16 is provided between the disc carriers 10, 11 and the spacer frames 2. The intermediate seal 16 can be located either on the spacer frames 2 or on the disc carriers 10, 11. The intermediate seal 16 can be designed as a separate component, for example, as a sealing cord or O-ring seal. Advantageously, the intermediate seal 16 is integrally molded either onto the spacer frame 2 or the disc carriers 10, 11. For this purpose, the intermediate seal 16 can be injection molded using a two-component injection molding process. Alternatively, the intermediate seal 16 can be foamed in place. In this case, the intermediate seal can be made of a polyurethane foam (PUR foam). The spacer frame 2 or the disc carriers 10, 11 can have a groove for receiving the intermediate seal. The groove can be designed analogously to the groove 5 described in connection with the end seal 4.

[0050] While the two spacer frames 2 are designed as identical parts in the exemplary embodiment, the disc carriers 10, 11 are different components.

[0051] In this embodiment, the disc carrier 10 is mounted as an outer part on the outside of the viewing window 1. The disc carrier 10 has several through-openings 10.1 distributed around its circumference. In this embodiment, two through-openings 10.1 are provided on each side. The disc carrier 11 is mounted as an inner part on the inside of the viewing window 1. The disc carrier 11 has several connecting elements designed in the form of screw bosses 11.1.

[0052] How the representation in Fig. 2As can be seen, several fastening elements 12 are provided, corresponding to the arrangement of the through-openings 10.1 and the screw bosses 11.1 arranged in alignment with them. The fastening elements 12 are screws. The fastening elements 12 can be inserted from the outside of the viewing window 1 through the through-openings 10.1 of the glazing support 10, the central openings of the spacers 7, 8 provided on the two spacer frames 2, and screwed into the screw bosses 11.1 of the glazing support 11. In this way, the components arranged on the inside of the viewing window 1 can be braced against the components arranged on the outside and against the wall 100. In this way, the viewing window 1 can be detachably fastened in the viewing opening 101.

[0053] For example, the representation in Fig. 6As can be seen, the disc carriers 10, 11 each have an axially extending plug-in area 10.2, 11.2. The disc carriers 10, 11 can be inserted into the spacer frames 2 via the plug-in areas 10.2, 11.2. The plug-in areas 10.2, 11.2 are formed circumferentially for this purpose. The outer contour of the plug-in areas 10.2, 11.2 is adapted to the inner contour of the cover frames 6 of the spacer frames 6 to form the plug connection.

[0054] Perpendicular to the direction of the axially extending plug-in areas 10.2, 11.2, the glazing supports 10, 11 each have a glazing frame 10.3, 11.3 supporting the viewing window 9. The glazing frame 10.3, 11.3 rests against the wall 100 from the outside. For sealing, an outer seal 17 is provided between the glazing frames 10.3, 11.3 and the wall 100. The outer seal 17 can either be designed as a separate component, for example as a sealing cord or O-ring seal, or be integrally molded onto the glazing supports 10, 11. For this purpose, the outer seal 17 can be injection-molded using a two-component injection molding process. Alternatively, the outer seal 17 can be foamed in place. In this case, the outer seal 17 can, in particular, consist of a polyurethane foam. The glazing supports 10, 11 can have a groove for receiving the intermediate seal. The groove can be designed analogously to the groove 5 described in connection with the end seal 4.

[0055] As the depictions in Fig. 2 and Fig. 6 To further indicate this, a cover 13 is provided on the outside of the viewing window 1. The fastening elements 12 are covered by the cover 13. A corresponding cover is not required on the inside.

[0056] How the representation in Fig. 6This also indicates that the viewing window 1 is designed for a specific wall thickness W of the wall 100 and can only be used with this type of wall thickness W. This is because the glare collars 6 of the spacers 2 are adapted to the wall thickness W of the wall 100 such that their depth a corresponds to half the wall thickness W. In this way, it is ensured that the end faces 3 of the glare collars 6 of the spacer frames 2 abut each other in the middle of the wall 100 and that the end-face seals 4 provided on the end faces 3 experience the necessary compression for an airtight seal of the interior of the viewing window 1.

[0057] To enable the use of the viewing window 1 with different wall thicknesses W, it is necessary to provide a glare collar 6 with a different depth a on the spacer frame 2. Advantageously, an interchangeable insert can be provided for this purpose in the injection mold used to manufacture the spacer frame 2. Different wall thicknesses W can be represented using one or more of these interchangeable inserts without having to change the entire mold. By using appropriate interchangeable inserts, different spacer frames 2 can be manufactured in a simple and cost-effective manner.

[0058] While the spacer frames 2 in the exemplary embodiment are designed as identical parts and their baffle collars 6 have the same depth a, spacer frames 2 can also be used that differ in depth a but are otherwise identical in construction. This allows the spacer frames 2 to be used as pairs for different wall thicknesses W, with their added depths a corresponding to the wall thickness W. Advantageously, the baffle collars 6 can have a depth a of 15 mm, 20 mm, and 30 mm.These depths a allow for the representation of common wall thicknesses W of 30 mm (spacer frames designed as identical parts with a depth a of 15 mm), 35 mm (spacer frames with different depths a of 15 mm and 20 mm), 40 mm (spacer frames designed as identical parts with a depth a of 20 mm), 45 mm (spacer frames with different depths a of 15 mm and 30 mm), 50 mm (spacer frames with different depths a of 20 mm and 30 mm), and 60 mm (spacer frames designed as identical parts with a depth a of 15 mm). However, other depths a may also be advantageous.

[0059] The end seals 4 provided between the spacer frames 2, the intermediate seals 16 provided between the spacer frames 2 and the disc carriers 10, 11, as well as the outer seals 17 provided on the disc carriers 10, 11, can advantageously be arranged in a groove of the respective adjacent component and manufactured in a multi-component injection molding process or by foaming, in particular with PUR foam, onto one of the adjacent components, see also Fig. 4 .

[0060] In the exemplary embodiment according to the Figs. 1 to 6A light source 14 is provided in the lower area of ​​the viewing window 1, which illuminates the viewing area of ​​the viewing window, i.e., the area that can be observed through the viewing window 1. The light source 14 can be an LED. The viewing window 1 has a light source receptacle 15 for receiving the light source 14, which is formed by one side 6.4 of the glare collar 6 and also of the adjacent lens supports 10, 11 being offset radially inwards. A battery or similar device for operating the light source 14 can also be housed in the light source receptacle. The light source 14 can be operated from the outside of the viewing window 1 in the area of ​​the lens support 10 via an operating element 14.1. The operating element 14.1 can be designed as a switch by which the light source 14 can be switched on and off.The control element 14 can also be designed in the manner of a push-button switch such that the light source 14 illuminates for a temporary period of time when the control element 14.1 is actuated and then switches off automatically.

[0061] The light source 14 can be inserted as a mounting unit into an axial opening 15.1 of the receptacle 15 and fastened there by means of fastening elements 14.2.

[0062] In contrast to the design as depicted in the Figs. 1 to 6 The design is based on the Fig. 7 and 8 around a viewing window 1 without a corresponding light source 14. In this embodiment, the opening 15.1 of the light source receptacle 15 is closed by a blanking cap 19. Otherwise, the design corresponds to the Figure 7 and 8 depicted design in all details of the one described Figures 1 to 6 depicted design.

[0063] The viewing window 1 can therefore be operated either with or without light source 14.

[0064] As explained above, the viewing window 1 according to the invention is characterized by a design that is both simple and reliably protected against external contaminants and ingress of moisture. For this purpose, the viewing window 1 has an end seal 3 in the area of ​​the end faces 3 of the glare collars 6 of the spacer frames 2, which seals the spacer frames 2 that extend into the viewing opening 101. According to the invention, the end seal 4 is designed as a half-seal, which makes it possible to use spacer frames 2 that are identical parts or spacer frames 2 that differ only in the depth a of their glare collar 6. Reference symbol:

[0065] 1 Viewing window 2 Spacer frame 3 Front side 4 Front seal 5 Groove 6 Glare collar 6.1 Side 6.2 Side 6.3 Side 6.4 Side 7 Spacer 8 Spacer 9 Viewing lens 10 Lens support 10.1 Through opening 10.2 Plug-in area 10.3 Lens frame 11 Lens support 11.1 Screw boss 11.2 Plug-in area 11.3 Lens frame 12 Fastener 13 Cover 14 Light source 14.1 Control element 14.2 Fastener element 15 Light source holder 15.1 Opening 16 Intermediate seal 17 Outer seal 18 Connection area 19 Blanking cap 100Wall 101Viewing opening 102Filler R1 direction R2 direction Wwall thickness aDepth

Claims

1. Viewing window (1) for installation in a viewing opening (101), in particular a viewing opening (101) of a ventilation and air conditioning system, with two spacer frames (2) that can be inserted into the viewing opening (101) from opposite directions (R1, R2) and are adjacent to each other via their end faces (3), wherein an end seal (4) is provided on the end faces (3) for sealing the two spacer frames (2) against each other, characterized in that the end seals (4) are designed as seal halves and are arranged in such a way that the end seals (4) of the two spacer frames (2) lying against each other form a continuous overall seal.

2. Viewing window according to claim 1, characterized in that the end seals (4) extend over half the circumference of the spacer frame (2).

3. Viewing window according to one of the preceding claims, characterized in that the end seal (4) is connected to the end face (3) in one piece.

4. Viewing window according to one of the preceding claims, characterized in that the spacer frames (2) have several spacers (7, 8) distributed around their circumference.

5. Viewing window according to claim 4, characterized in that the spacers (7, 8) are designed and arranged in such a way that the spacers (7, 8) of the two spacer frames (2) lie against each other.

6. Viewing window according to claim 5, characterized in that the spacers (7, 8) are designed as spacer plugs, wherein a first group of spacers (7) is designed as male spacer plugs and a second group of spacers (8) is designed as female spacer plugs.

7. Viewing window according to one of the preceding claims, characterized in that the two spacer frames (2) are designed as identical parts or in that the two spacer frames (2) differ in the depth (a) of the outer frames (6).

8. Viewing window according to one of the preceding claims, characterized in that a pane carrier (10, 11) carrying a viewing pane (9) is arranged on each of the spacer frames (2).

9. Viewing window according to claim 8, characterized in that the two spacer frames (2) and the two pane carriers (10, 11) are detachably fastened to the viewing opening (101) by fastening means (12).

10. Viewing window according to claim 9, characterized in that the fastening means (12) are designed as screws, whereby one of the pane carriers (10) is designed with through-openings (10.1) and the other pane carrier (11) is designed with screw domes (11.1) for receiving the fastening means (12).

11. Viewing window according to claim 10, characterized in that some, preferably all, of the fastening means (12) extend through the spacers (7, 8).

12. Viewing window according to one of claims 10 or 11, characterized in that the pane support (10) is provided with a cover (13) concealing the fastening means (12).

13. Viewing window according to one of the preceding claims, characterized by a light source (14) for illuminating the viewing area of the viewing window (1).

14. Viewing window according to claim 13, characterized in that the spacer frames (2) have a light source holder (15) for holding the light source (14).

15. Viewing window according to claim 14, characterized in that the light source holder (15) is arranged radially outside the end seals (4).