Microfluidic burner for microscopic optical diagnostic tests

Abstract

The application provides a micro-fluidic burner for microscopic optical diagnosis experiment, and belongs to the technical field of online combustion diagnosis. The burner comprises a mounting assembly for fixing the micro-fluidic burner, a cavity assembly for connecting with an experimental gas path, a nozzle connected with the gas path in the cavity assembly for realizing ignition combustion, a nozzle fixing assembly for fixing the nozzle on the cavity assembly, and a light window for transmitting laser and weak scattering signals of optical diagnosis to observe combustion. The cavity assembly comprises a sealingly connected upper cavity and lower cavity. The micro-fluidic burner can ignite methane, acetylene, ethylene and other gas flames, has the characteristics of small volume and replaceable nozzle, realizes positioning and fitting of the combustion nozzle by adopting a conical surface structure, can replace combustion nozzles with different structures according to actual research needs, can be used for microscopic diagnosis in the optical aspect, and can be particularly applied to in-situ microscopic Raman spectrum diagnosis of combustion carbon deposition.

Description

Technical Field

[0001] This application belongs to the field of online combustion diagnostic technology, specifically relating to a microjet burner for microscopic optical diagnostic testing. Background Technology

[0002] Aero engines are the heart of aircraft, a vital national asset, and the crown jewel of manufacturing. Aviation fuel serves as the engine's pacemaker and power source. The main combustion chamber is one of the three core components of an aero engine (compressor, combustion chamber, and turbine). The combustion chamber is a high-temperature, high-pressure environment where intense physical and chemical reactions occur, easily leading to coking and carbon buildup that endangers the safe operation of the aero engine and pollutes the environment.

[0003] Current research on combustion carbon deposits mostly employs offline, indirect measurement methods to analyze the microscopic morphology and properties of the carbon deposits. For high-resolution optical diagnostics, a microjet burner needs to be designed to provide flame and carbon deposit conditions that match microscopic techniques. Summary of the Invention

[0004] The purpose of this application is to provide a microjet burner that can ignite gas flames such as methane, acetylene, and ethylene, and features small size and replaceable nozzles. It can be used for optical microscopic diagnosis, especially for in-situ microscopic Raman spectroscopy diagnosis of burning carbon deposits.

[0005] To achieve the above objectives, this application provides the following technical solution: a microjets burner for microscopic optical diagnostic experiments, the burner comprising a mounting assembly for fixing the microjets burner, a cavity assembly for connecting to a test gas path, a nozzle connected to the gas path within the cavity assembly for ignition and combustion, a nozzle fixing assembly for fixing the nozzle to the cavity assembly, and a light window for allowing laser light and weak scattered signals for optical diagnostics to pass through to observe the combustion.

[0006] The cavity assembly includes a sealed upper cavity and a lower cavity.

[0007] The microjet burner for microscopic optical diagnosis provided in this application also has the following features: the mounting assembly includes multiple countersunk through holes for fixing the burner, threaded holes for mounting and fixing the lower cavity, and raised edges for positioning the lower cavity; the mounting assembly also has a hollow structure for the mounting plate.

[0008] The microjet burner for microscopic optical diagnosis provided in this application also has the feature that the upper cavity and the lower cavity are sealed together by a large sealing ring.

[0009] The microjet burner for microscopic optical diagnostics provided in this application also has the following features: the lower cavity includes a lower cavity through hole and a lower cavity bottom plate edge that are installed and cooperate with the mounting assembly; a lower cavity circular tube connected to the test gas path; an upper lower cavity through hole for fixing the lower cavity to the upper cavity; a lower cavity sealing ring mounting position for placing a large sealing ring; and a lower cavity sealing ring mounting position groove for removing the large sealing ring.

[0010] The microjet burner for microscopic optical diagnosis provided in this application also has the following features: the upper cavity has a square structure, the upper cavity includes a bottom through hole for mounting and cooperating with the lower cavity, a circular tube for the upper cavity connected to the test gas path, a first sealing ring mounting position for placing a large sealing ring, a sealing ring mounting position groove for removing the large sealing ring, and an inclined surface for the upper cavity to cooperate and seal with the nozzle fixing assembly.

[0011] The microjet burner for microscopic optical diagnosis provided in this application also has the following features: the upper cavity and the nozzle are sealed together by a small sealing ring; the upper cavity further includes a second sealing ring mounting position for placing the small sealing ring, a pressure cap for pressing the small sealing ring, and a threaded hole for installing the pressure cap.

[0012] The gland includes a gland protrusion for pressing the small sealing ring, a through hole for screw installation that mates with the threaded hole of the upper cavity sealing ring, and a gland central hole for the nozzle to pass through.

[0013] The microjets burner for microscopic optical diagnostics provided in this application also features that the nozzle fixing assembly includes a microporous plate placed on the upper cavity and a top cover fixed on the upper cavity.

[0014] The microporous plate has a beveled surface for placing the microporous plate on the upper cavity and a conical hole for placing the nozzle. The beveled surface is positioned and engaged with the upper cavity, and the conical hole is positioned and engaged with the nozzle.

[0015] The top cover has a square structure and includes a top cover through hole for fixing the top cover to the upper cavity and a top cover protrusion groove for placing the light window.

[0016] The microjet burner for microscopic optical diagnostics provided in this application also has the following features: the nozzle is provided with a nozzle cone surface that is positioned and engaged with the nozzle fixing assembly, a nozzle bottom tube that passes through the upper cavity for outputting gas from the lower cavity to the upper space, and a replaceable nozzle irregular top.

[0017] The microjet burner for microscopic optical diagnostics provided in this application also has the feature that the nozzle top profile includes one selected from a conical nozzle top and an arched nozzle top.

[0018] The microjets burner for microscopic optical diagnostics provided in this application also features a rectangular optical window mounted on the nozzle fixing assembly. The optical window is equipped with a quartz plate and a window purging structure, which is used to purge carbon soot deposited on the optical window.

[0019] The light window purging structure includes a first light window purging structure component and a second light window purging structure component. The first light window purging structure component is provided with a first light window purging structure component inclined surface, and the second light window purging structure component is provided with a second light window purging structure component inclined surface. The first light window purging structure component inclined surface and the second light window purging structure component inclined surface are assembled to form a slit for ejecting purging gas.

[0020] Beneficial effects

[0021] The microjet burner for microscopic optical diagnosis provided in this application can ignite gas flames such as methane, acetylene, and ethylene. It features small size and replaceable nozzles. The conical structure is used to achieve the positioning and matching of the combustion nozzle. The combustion nozzles with different structures can be replaced according to actual research needs. It can be used for optical microscopic diagnosis, especially for in-situ microscopic Raman spectroscopy diagnosis of burning carbon deposits.

[0022] The microjets burner for microscopic optical diagnosis provided in this application has a square structure and is equipped with a light window with good light transmittance, which facilitates the transmission of laser and light scattering signals for microscopic optical diagnosis. Furthermore, the burner can achieve precise positioning for repeated installation and can completely observe the combustion state from the start of ignition. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a structural diagram of the microjet burner for microscopic optical diagnostics provided in the embodiments of this application;

[0025] Figure 2 This is a cross-sectional view of the microjet burner for microscopic optical diagnostics provided in the embodiments of this application;

[0026] Figure 3 This is an assembly diagram of the microjets burner for microscopic optical diagnostics provided in the embodiments of this application;

[0027] Figure 4 This is an assembly diagram showing the sealing structure between the upper cavity and the lower cavity in an embodiment of this application.

[0028] Figure 5 This is an assembly diagram showing the sealing structure between the upper cavity, orifice plate, and nozzle in an embodiment of this application.

[0029] Figure 6 These are cross-sectional views of two types of nozzles in the embodiments of this application;

[0030] Figure 7 This is a diagram of the light window assembly structure in an embodiment of this application;

[0031] Figure 8 This is a schematic diagram of the optical window purging structure in an embodiment of this application;

[0032] Figure 9 This is a schematic diagram of an experiment using the burner described in this embodiment to perform in-situ Raman spectroscopy diagnosis of combustion deposits;

[0033] Figure 10 for Figure 9 The experimental results of the experiment are shown in the figure.

[0034] The components include: 1. Mounting plate; 11. Countersunk through hole; 12. Threaded hole in mounting plate; 13. Raised edge; 14. Hollowed-out structure of mounting plate; 2. Lower cavity; 21. Lower cavity round tube; 22. Edge of lower cavity bottom plate; 23. Lower cavity through hole; 24. Upper through hole of lower cavity; 25. Lower cavity sealing ring mounting position; 251. Large sealing ring; 26. Lower cavity sealing ring mounting position groove; 3. Upper cavity; 31. Upper cavity 32. Bottom through hole of upper cavity; 33. Upper through hole of upper cavity; 34. First sealing ring mounting position of upper cavity; 35. Sealing ring mounting groove of upper cavity; 36. Second sealing ring mounting position of upper cavity; 361. Small sealing ring; 37. Threaded hole of sealing ring gland of upper cavity; 371. Gland; 3711. Gland protrusion; 3712. Through hole of gland; 3713. Middle hole of gland; 38. Inclined surface of upper cavity; 4. Microporous plate; 41. Microporous plate inclined surface; 42. Microporous plate conical hole; 5. Top cover; 51. Top cover through hole; 52. Top cover raised groove; 6. Nozzle; 61. Nozzle conical surface; 62. Nozzle bottom circular tube; 63. Nozzle irregular top; 631. Conical nozzle top; 632. Arched nozzle top; 7. Light window; 71. Quartz plate; 72. Light window purging structure; 721. First light window purging structure component; 7211. First light window purging structure component inclined surface; 722. Second light window purging structure component; 7221. Second light window purging structure component inclined surface; 8. Long working distance objective lens; 90. Backfire prevention valve; 91. First oxygen mass flow controller; 92. First nitrogen mass flow controller; 93. Second oxygen mass flow controller; 94. Second nitrogen mass flow controller; 95. Fuel mass flow controller. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be noted that these embodiments are not intended to limit the present application. Equivalent transformations or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present application.

[0036] In the description of the embodiments of this application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the creation of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the creation of this application.

[0037] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0038] The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0039] like Figures 1-8 As shown, a microjets burner for microscopic optical diagnostic tests is provided. The burner includes a mounting assembly for fixing the microjets burner, a cavity assembly for connecting to a test gas path, a nozzle 6 connected to the gas path inside the cavity assembly for ignition and combustion, a nozzle fixing assembly for fixing the nozzle 6 to the cavity assembly, and a light window 7 for allowing laser and weak scattering signals for optical diagnostics to pass through to observe the combustion. The cavity assembly includes an upper cavity 3 and a lower cavity 2 that are sealed together.

[0040] The burner provided in the above embodiments can achieve precise positioning for repeated installation and can completely observe the combustion state from the start of ignition.

[0041] In some embodiments, the mounting assembly includes a mounting plate 1, multiple countersunk through holes 11 for fixing the burner, a mounting plate threaded hole 12 for mounting and fixing the lower cavity 2, and a raised edge 13 for positioning the lower cavity 2. The mounting assembly also has a mounting plate hollow structure 14.

[0042] In the above embodiment, screws are used to fix the mounting plate 1 to other structures through the countersunk holes 11, providing a stable support for the burner. Multiple screws are used to fix the lower cavity 2 to the mounting plate 1 through the threaded holes 12 of the mounting plate. The lower cavity 2 is aligned with the raised edge 13 to achieve precise positioning. The hollow structure 14 of the mounting plate reduces the overall weight of the mounting edge.

[0043] In some embodiments, the upper cavity 3 and the lower cavity 2 are sealed together by a large sealing ring 251.

[0044] In some embodiments, the lower cavity 2 includes a lower cavity through hole 23 that mates with the mounting assembly, a lower cavity bottom plate edge 22, a lower cavity circular tube 21 connected to the test gas path, an upper lower cavity through hole 24 for mounting and fixing the lower cavity 2 to the upper cavity 3, a lower cavity sealing ring mounting position 25 for placing the large sealing ring 251, and a lower cavity sealing ring mounting position groove 26 for removing the large sealing ring 251.

[0045] In the above embodiment, the lower cavity bottom plate edge 22 is aligned with the raised edge 13 of the mounting plate to achieve accurate positioning. The lower cavity through hole 23 is used to install the lower cavity 2 into the threaded hole 12 of the mounting plate by passing screws through the lower cavity through hole 23. The upper through hole 24 of the lower cavity is used for installation with the upper cavity 3. The lower cavity sealing ring mounting position 25 is used to place the large sealing ring 251. The lower cavity sealing ring mounting position groove 26 facilitates the removal of the large sealing ring 251 from the lower cavity sealing ring mounting position 25.

[0046] During the test, if it is necessary to disassemble the burner, first remove the screws in the upper through hole 24 of the lower cavity and the threaded hole 12 of the mounting plate, and keep the mounting plate 1 in the installation state of the test chamber table or tabletop.

[0047] In some embodiments, the upper cavity 3 has a square structure. The upper cavity 3 includes a bottom through hole 32 that is installed and cooperates with the lower cavity 2, an upper through hole 33 that is installed and cooperates with the nozzle fixing assembly, an upper cavity circular tube 31 that is connected to the test gas path, an upper cavity first sealing ring mounting position 34 for placing the large sealing ring 251, an upper cavity sealing ring mounting position groove 35 for removing the large sealing ring 251, and an upper cavity inclined surface 38 for sealing in cooperation with the nozzle fixing assembly.

[0048] In the above embodiment, the bottom through hole 32 of the upper cavity is used for installation with the lower cavity 2, and the installation method is to fix it with screws and nuts. The upper through hole 33 of the upper cavity is used for installation with the top cover 5. The first sealing ring mounting position 34 of the upper cavity is used to place the large sealing ring 251. The sealing ring mounting groove 35 of the upper cavity facilitates the removal of the large sealing ring 251 from the first sealing ring mounting position 34 of the upper cavity. The inclined surface 38 of the upper cavity is used to achieve a mating seal with the inclined surface 41 of the microporous plate.

[0049] In some embodiments, the upper cavity 3 and the nozzle 6 are sealed together by a small sealing ring 361. The upper cavity 3 also includes an upper cavity second sealing ring mounting position 36 for placing the small sealing ring 361, a pressure cap 371 for pressing the small sealing ring 361, and an upper cavity sealing ring pressure cap threaded hole 37 for installing the pressure cap 371. The pressure cap 371 includes a pressure cap protrusion 3711 for pressing the small sealing ring 361, a pressure cap through hole 3712 for screw installation in conjunction with the upper cavity sealing ring pressure cap threaded hole 37, and a pressure cap central hole 3713 for the nozzle 6 to pass through.

[0050] In the above embodiment, the second sealing ring mounting position 36 of the upper cavity is used to place the small sealing ring 361. The threaded hole 37 of the upper cavity sealing ring gland is used to install the gland 371. The gland protrusion 3711 is used to press the small sealing ring 361. The gland through hole 3712 is used to fix the gland 371 to the threaded hole 37 of the upper cavity sealing ring gland with screws. The gland central hole 3713 is used to pass through the bottom circular tube of the nozzle.

[0051] In some embodiments, the nozzle fixing assembly includes a microporous plate 4 placed on the upper cavity 3 and a top cover 5 fixed on the upper cavity 3.

[0052] The microporous plate 4 is provided with a microporous plate inclined surface 41 for placing the microporous plate 4 on the upper cavity 3 and a microporous plate conical hole 42 for placing the nozzle 6. The microporous plate inclined surface 41 is positioned and engaged with the upper cavity 3, and the microporous plate conical hole 42 is positioned and engaged with the nozzle 6.

[0053] The top cover 5 has a square structure and a hollow structure. It has a square through hole with a side length of 40 mm in the middle. The top cover 5 includes a top cover through hole 51 for fixing the top cover 5 to the upper cavity 3 and a top cover protrusion groove 52 for placing the light window 7.

[0054] In some embodiments, the nozzle 6 is provided with a nozzle cone surface 61 that is positioned and engaged with the nozzle fixing assembly, a nozzle bottom circular tube 62 that passes through the upper cavity 3 to output gas from the lower cavity 2 to the upper space, and a replaceable nozzle irregular top 63.

[0055] In some embodiments, the nozzle asymmetry tip 63 includes one selected from a conical nozzle tip 631 and an arched nozzle tip 632. For example... Figure 6 The image shows a cross-sectional view of two different newly installed nozzles.

[0056] In some embodiments, the light window 7 is a rectangular structure and is mounted on the nozzle fixing assembly. The side length of the light window is approximately 40mm. One side of the light window is a light-transmitting plate with a quartz plate 71, approximately 3mm thick, made of a highly transparent material. The other three sides are opaque metal surfaces. A light window purging structure 72 is provided below the quartz plate 71. The light window purging structure 72 uses gas to purge the light window 7, preventing carbon soot from depositing on the light window 7 and affecting observation. The light window purge structure 72 includes a first light window purge structure component 721 and a second light window purge structure component 722. The first light window purge structure component 721 is provided with a first light window purge structure component inclined surface 7211, and the second light window purge structure component 722 is provided with a second light window purge structure component inclined surface 7221. The first light window purge structure component inclined surface 7211 and the second light window purge structure component inclined surface 7221 are assembled to form a slit for ejecting purge gas, and the slit width is approximately 0.2 mm.

[0057] To verify the compatibility of the microjets burner with the combustion carbon deposit optical diagnostic system, an acetylene flame was ignited using the microjets provided in any of the aforementioned embodiments. Specific experiments were conducted as follows: Figure 9 As shown, a micro Raman spectrometer with a long working distance objective lens 8 was used to detect combustion carbon deposits. The large sealing ring 251 and the small sealing ring 361 were made of graphite. The light window 7 was made of quartz, capable of withstanding high temperatures and achieving high light transmittance, with a side length of approximately 40 mm and a thickness of approximately 3 mm. The nozzle's irregularly shaped top 63 was a conical nozzle top 631. The upper chamber's circular tube 31 was connected to a first oxygen mass flow controller 91 and a first nitrogen mass flow controller 92, providing accompanying gas to the burner. The lower chamber's circular tube 21 was connected to a second oxygen mass flow controller 93 and a second nitrogen mass flow controller 94, which, via a backfire preventer 90, were connected to a fuel mass flow controller 95 to provide fuel gas for in-situ detection of combustion carbon deposits. The experimental results are as follows... Figure 10 As shown, the characteristic peaks D and G of carbon can be detected. This indicates that the aforementioned microjet burner can be used in conjunction with a microspectrometer to achieve in-situ diagnosis of combustion carbon deposits.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above description is merely a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A microjet burner for microscopic optical diagnostic experiments, characterized in that, The burner includes a mounting assembly for fixing the microjet burner, a cavity assembly for connecting to the test gas path, a nozzle (6) connected to the gas path inside the cavity assembly for ignition and combustion, a nozzle fixing assembly for fixing the nozzle (6) on the cavity assembly, and a light window (7) for allowing laser and weak scattered signals for optical diagnosis to pass through to observe the combustion. The cavity assembly includes a sealed upper cavity (3) and a lower cavity (2). The nozzle (6) is provided with a nozzle cone surface (61) that is positioned and engaged with the nozzle fixing assembly, a nozzle bottom tube (62) that passes through the upper cavity (3) to output gas from the lower cavity (2) to the upper space, and a replaceable nozzle irregular top (63). The light window (7) has a square cylindrical structure and is installed on the nozzle fixing assembly. The light window (7) is provided with a quartz plate (71) and a light window purging structure (72). The light window purging structure (72) is used to purge the carbon soot deposited on the light window (7). The light window purge structure (72) includes a first light window purge structure component (721) and a second light window purge structure component (722). The first light window purge structure component (721) is provided with a first light window purge structure component inclined surface (7211), and the second light window purge structure component (722) is provided with a second light window purge structure component inclined surface (7221). The first light window purge structure component inclined surface (7211) and the second light window purge structure component inclined surface (7221) are assembled to form a slit for ejecting purge gas. The nozzle top (63) includes one selected from a conical nozzle top (631) and an arched nozzle top (632).

2. The microjet burner for microscopic optical diagnostic experiments according to claim 1, characterized in that, The mounting assembly includes a mounting plate (1), multiple countersunk through holes (11) for fixing the burner, threaded holes (12) for mounting and fixing the lower cavity, and a raised edge (13) for positioning the lower cavity. The mounting assembly also includes a perforated mounting plate structure (14).

3. The microjet burner for microscopic optical diagnostic experiments according to claim 1, characterized in that, The upper cavity (3) and the lower cavity (2) are sealed together by a large sealing ring (251).

4. The microjets burner for microscopic optical diagnostic tests according to claim 3, characterized in that, The lower cavity (2) includes a lower cavity through hole (23) that mates with the mounting assembly and an edge (22) of the lower cavity bottom plate, a lower cavity circular tube (21) that connects to the test gas path, an upper lower cavity through hole (24) for mounting and fixing the lower cavity (2) and the upper cavity (3), a lower cavity sealing ring mounting position (25) for placing the large sealing ring (251), and a lower cavity sealing ring mounting position groove (26) for removing the large sealing ring (251).

5. The microjet burner for microscopic optical diagnostic testing according to claim 3, characterized in that, The upper cavity (3) has a square structure. The upper cavity (3) includes a bottom through hole (32) that is installed and cooperates with the lower cavity (2), an upper through hole (33) that is installed and cooperates with the nozzle fixing assembly, an upper cavity round tube (31) that is connected to the test gas path, an upper cavity first sealing ring mounting position (34) for placing the large sealing ring (251), an upper cavity sealing ring mounting position groove (35) for removing the large sealing ring (251), and an upper cavity inclined surface (38) for sealing in cooperation with the nozzle fixing assembly.

6. The microjets burner for microscopic optical diagnostic tests according to claim 5, characterized in that, The upper cavity (3) and the nozzle (6) are sealed together by a small sealing ring (361). The upper cavity (3) also includes an upper cavity second sealing ring mounting position (36) for placing a small sealing ring (361), a pressure cap (371) for pressing the small sealing ring, and an upper cavity sealing ring pressure cap threaded hole (37) for installing the pressure cap (371). The gland (371) includes a gland protrusion (3711) for pressing the small sealing ring (361), a gland through hole (3712) for screw installation in conjunction with the upper cavity sealing ring gland thread hole (37), and a gland central hole (3713) for the nozzle (6) to pass through.

7. The microjet burner for microscopic optical diagnostic experiments according to claim 1, characterized in that, The nozzle fixing assembly includes a microporous plate (4) placed on the upper cavity (3) and a top cover (5) fixed on the upper cavity (3). The microporous plate (4) is provided with a microporous plate inclined surface (41) for placing the microporous plate (4) on the upper cavity (3) and a microporous plate conical hole (42) for placing the nozzle (6). The microporous plate inclined surface (41) is positioned and engaged with the upper cavity (3), and the microporous plate conical hole (42) is positioned and engaged with the nozzle (6). The top cover (5) has a square structure and includes a top cover through hole (51) for fixing the top cover (5) to the upper cavity (3) and a top cover protrusion groove (52) for placing the light window (7).

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