Automatic cooling air ring

Abstract

An automatic cooling air ring includes an air ring body and an air chamber, wherein an annular cavity and an annular first air duct are formed inside the air ring body, two sets of temperature control devices with semiconductor refrigeration plates are respectively arranged on the upper and lower sides of the annular cavity, one end of the temperature control device is arranged at the air inlet of the air ring body, the air inlet is connected to the air chamber, and the other end is connected to the annular first air duct. After the air in the air chamber enters from the air inlet, it passes through the cooling labyrinth air duct formed between the two sets of temperature control devices and is cooled, and then discharged to the annular first air duct, and finally the film bubble is cooled. The present invention finally realizes the cooling function of the film bubble through the cooperation between various parts. Compared with the prior art, when a part of the film bubble is thicker, the temperature of the wind cooling the part can be adjusted by the semiconductor refrigeration plate, and no heating work is required, so the cooling efficiency of the film bubble can be greatly improved.

Description

Technical Field

[0001] The invention relates to an air ring, in particular to an automatic cooling air ring, belonging to the field of cooling equipment. Background Art

[0002] Plastic film is a common plastic product. It can be produced by calendering, extrusion, blow molding and other process methods. Blown film is to melt the plastic raw materials through an extruder to extrude the raw materials into a thin tube, and then blow it up with compressed air while it is hot. After cooling and shaping, the film product is obtained. Nowadays, the processing and production of plastic film is generally completed by film blowing machines. As an important component of film blowing machines, the air ring is mainly responsible for cooling and shaping the inflated film bubbles. During the cooling process, if a part of the film bubble is thicker than other parts, the cooling speed of this part of the film bubble will be faster. Under the same cooling conditions, the hardness of this part of the film bubble will be higher than that of other parts and it cannot be blown up. In order to solve this technical problem, the air ring currently used on the market is a wind temperature type air ring, that is, a wind ring that regulates the temperature of the cold air by artificial heating. The method adopted to solve the above technical problem is that when it is found that the thickness of the film bubble is large, the cold air cooling this part of the film bubble is artificially heated to increase the temperature of the cold air, thereby avoiding the cooling speed of this part of the film bubble too fast. However, the purpose of the air ring itself is to cool the film bubble with cold air. Heating the cold air is undoubtedly contrary to the purpose of cooling, and actually sacrifices the cooling efficiency. In addition, this wind temperature type air ring needs to manually adjust the temperature continuously according to the cooling situation of the film bubble, so the range of controllable temperature difference is small and the overall efficiency is not high. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides an automatic cooling air ring with high cooling efficiency and large controllable temperature difference.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an automatic cooling air ring, including an air ring body and an air chamber, an annular cavity and an annular first air duct are formed inside the air ring body, two sets of temperature control devices with semiconductor refrigeration plates are respectively arranged on the upper and lower sides of the annular cavity, one end of the temperature control device is arranged at the air inlet of the air ring body, the air inlet is connected to the air chamber, and the other end is connected to the annular first air duct. After the air in the air chamber enters from the air inlet, it passes through the cooling maze air duct formed between the two sets of temperature control devices and is cooled, and then is discharged to the annular first air duct, finally cooling the membrane bubble.

[0005] Preferably, an air inlet nozzle is provided on the outer side of the air chamber.

[0006] Preferably, the temperature control device includes a semiconductor refrigeration plate, a first heat sink and a heat dissipation structure, one side of the semiconductor refrigeration plate is connected to the first heat sink, and the other side is connected to the heat dissipation structure. The wind in the wind chamber passes through the cooling maze air duct formed between the first heat sinks of the two sets of temperature control devices, and is temperature-controlled by the semiconductor refrigeration plate. At the same time, the heat dissipation structure continues to dissipate heat from the semiconductor refrigeration plate after absorbing heat, so that the semiconductor refrigeration plate can work normally.

[0007] Preferably, the first heat sinks of the two sets of temperature control devices are interconnected to form a diverter with a hollow interior, which is used to increase the contact area between the wind and the refrigeration fins and enhance the exchange between them, while allowing the air to evenly and smoothly enter the cooling maze air duct for cooling.

[0008] Preferably, the heat dissipation structure is a heat exchanger and a liquid refrigerant, one side of the heat exchanger is connected to the semiconductor refrigeration plate, and the other side is connected to the liquid refrigerant.

[0009] Preferably, the heat exchanger is a water storage chamber, and the liquid refrigerant is a water circulation component. Through the action of the water circulation component, the water in the water storage chamber can be continuously cooled so that it can be circulated.

[0010] Preferably, the heat dissipation structure comprises a second heat sink and an air heat dissipation component, one side of the second heat sink is connected to the semiconductor refrigeration plate, and the other side is provided with an air heat dissipation component.

[0011] Preferably, heat-conducting medium is provided on both sides of the semiconductor refrigeration plate.

[0012] Preferably, the first heat sink and the heat exchanger are respectively connected to the semiconductor refrigeration plate via a heat conducting medium.

[0013] Preferably, the first heat sink and the second heat sink are respectively connected to the semiconductor refrigeration sheet via a heat conducting medium.

[0014] Preferably, the heat conducting medium is heat conducting glue.

[0015] Preferably, the wind ring main body includes an upper wind cover, an wind ring seat, a support member, an air outlet dividing ring and a wind protection ring. The air inlet is arranged at the lower end of the upper wind cover. The upper wind cover is respectively connected to the wind ring seat and the support member, and an annular cavity is formed inside after the connection. The wind ring seat is connected to the air outlet dividing ring, and after the connection, an annular first air duct is formed with the support member. The wind protection ring is connected to the support member in a liftable manner.

[0016] Preferably, the support member includes an intermediate support assembly and a movable adjustment ring, the intermediate support assembly is connected to the upper wind cover, and the upper and lower sides of the movable adjustment ring are respectively provided with lifting adjustment structures, the intermediate support assembly is connected to the movable adjustment ring through the lifting adjustment structure on the lower side, and the wind protection ring is connected to the movable adjustment ring through the lifting adjustment structure on the upper side.

[0017] Preferably, the lifting and lowering adjustment structures on both sides of the movable adjustment ring are threads.

[0018] Preferably, the intermediate support assembly is connected to the movable adjustment ring via a thread on the lower side, and the thread can adjust the height of the movable adjustment ring, thereby adjusting the air volume and wind speed.

[0019] Preferably, the threads on the upper sides of the movable adjustment ring and the wind protection ring are connected to the movable adjustment ring, and the threads can adjust the height of the wind protection ring to adapt to film bubbles with different blowing ratios.

[0020] Preferably, a handle is provided on the movable adjustable ring.

[0021] Preferably, the wind protection ring is provided with a first air leakage hole, and an adjustment ring is also provided at a corresponding position of the wind protection ring, and the adjustment ring is provided with a second air leakage hole. By rotating the position of the adjustment ring, the overlap degree of the first air leakage hole and the second air leakage hole can be controlled, thereby adjusting the size of the wind leaking from the first air leakage hole and the second air leakage hole, thereby adjusting the size of the lifting force to avoid shaking or other instability problems of the membrane bubble.

[0022] Preferably, it also includes a downwind duct plate arranged on the vent separation ring, the vent separation ring is provided with ventilation holes, and an annular second duct is formed between the downwind duct plate and the vent separation ring, and a part of the wind in the annular first duct enters the annular second duct from the ventilation holes, thereby pre-cooling the membrane bubble.

[0023] Preferably, it further comprises a positioning ring, wherein the positioning ring is connected to the air ring seat, and the temperature control device on the lower side of the annular cavity is arranged on the positioning ring.

[0024] Preferably, it also includes a heat insulation sheet, which is arranged on the inner wall of the annular cavity, and the temperature control device is connected to the heat insulation sheet.

[0025] Preferably, the cooling labyrinth air duct is a single-arc cooling labyrinth air duct.

[0026] Preferably, the cooling labyrinth air duct is a multi-S-shaped cooling labyrinth air duct.

[0027] Preferably, the cooling labyrinth air duct is a straight cooling labyrinth air duct.

[0028] Preferably, the cooling maze air duct is a triangular cooling maze air duct.

[0029] The present invention realizes the cooling function of the membrane bubble through the coordination between various parts. Compared with the prior art, when a part of the membrane bubble is thicker, the temperature of the wind cooling this part can be adjusted by the semiconductor refrigeration plate, and no heating work is required. Therefore, the cooling efficiency of the membrane bubble can be greatly improved; because the semiconductor refrigeration plate is automatically controlled, the range of controllable temperature difference is large and the accuracy is high; in addition, since the thermal inertia of the semiconductor refrigeration plate is very small and the cooling speed is fast, the maximum temperature difference can be achieved after power-on for a moment when the hot end dissipates heat well and the cold end is unloaded. Compared with the ordinary wind temperature type air ring operated manually, the overall adjustment response speed is faster; on the other hand, by adjusting the lifting and lowering adjustment structures on the upper and lower sides of the movable adjustment ring, the air volume and wind speed of the air ring can be adjusted, thereby forming different sizes of lifting forces in the air ring, so as to adapt to membrane bubbles of different specifications, so the overall applicability is stronger. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the assembly of the present invention.

[0031] Figure 2 yes Figure 1 Top view of the .

[0032] Figure 3 yes Figure 1 Bottom view of .

[0033] Figure 4 It is a schematic diagram of the movement direction of membrane bubbles.

[0034] Figure 5 It is a schematic cross-sectional view of the first embodiment of the present invention.

[0035] Figure 6 It is a schematic diagram of the heat dissipation structure including a water storage chamber and water circulation components.

[0036] Figure 7 It is a schematic diagram of a cooling labyrinth air duct that is a single arc cooling labyrinth air duct.

[0037] Figure 8 The cooling labyrinth air duct is a schematic diagram of a multi-S-shaped cooling labyrinth air duct.

[0038] Fig. 9 It is a schematic diagram showing that the cooling labyrinth air duct is a straight cooling labyrinth air duct.

[0039] Fig.10 It is a schematic diagram of a cooling maze air duct which is a triangular cooling maze air duct.

[0040] Fig.11 It is a schematic diagram of the adjustment of the middle support assembly, the movable adjustment ring and the wind protection ring.

[0041] Fig.12 It is a structural schematic diagram of the upper wind cover.

[0042] Fig.13 It is a schematic diagram of the structure of the wind protection circle.

[0043] Fig.14 It is a schematic diagram of the structure of the adjustment ring.

[0044] Fig.15 It is a schematic cross-sectional view of a second embodiment of the present invention.

[0045] Fig.16 It is a structural schematic diagram of the tuyere separation ring.

[0046] Fig.17 It is a structural schematic diagram of the downwind duct plate.

[0047] Fig.18 It is a schematic cross-sectional view of a third embodiment of the present invention.

[0048] Fig.19 It is a structural diagram of the diverter.

[0049] Fig. 20 It is a schematic diagram of a heat dissipation structure consisting of a second heat sink and an air heat dissipation component.

[0050] Fig.21 It is a schematic diagram of the wind flow direction when the present invention is in operation.

[0051] In the figure, 1-air chamber; 2-air inlet nozzle; 3-annular first air duct; 4-semiconductor refrigeration plate; 5-air inlet; 6-cooling labyrinth air duct; 7-membrane bubble; 8-upper air cover; 9-air ring seat; 10-middle support assembly; 11-air outlet separation ring; 12-wind protection ring; 13-movable adjustment ring; 14-handle; 15-first air leakage hole; 16-adjustment ring; 17-second air leakage hole; 18-first heat sink; 19-water storage chamber; 20-water circulation component; 21-thermal conductive glue; 22-positioning ring; 23-lower air duct plate; 24-ventilation hole; 25-annular second air duct; 26-second heat sink; 27-air heat dissipation component; 28-top cover; 29-lower cover; 30-thermal insulation plate; 31-connection end; 32-hole; 33-diverter. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Figure 1-Figure 14A first embodiment of the present invention is shown; Figure 1-Figure 14 As shown: an automatic cooling air ring, comprising an air ring body and an air chamber 1, an air inlet 2 is arranged on the outside of the air chamber 1 (the air inlet 2 can be connected to the air supply device of the film blowing machine, and the air supply device supplies air to the air chamber. The air supply device belongs to the prior art and will not be described in detail in this article), an annular cavity and an annular first air duct 3 are formed inside the air ring body, two sets of temperature control devices with semiconductor cooling plates 4 are respectively arranged on the upper and lower sides of the annular cavity, one end of the temperature control device is arranged at the air inlet 5 of the air ring body, and the air inlet 5 is connected to the air chamber 1 The air in the air chamber 1 enters through the air inlet 5, passes through the single arc cooling labyrinth air duct 6 formed between the two sets of temperature control devices (the shape of the cooling labyrinth air duct 6 can be modified to multiple S-shaped, straight, triangular or other shapes according to the cooling efficiency of the membrane bubble 7. The thicker the membrane bubble 7 is, the longer the path of the cooling labyrinth air duct 6 needs to be arranged, and the greater the overall curvature), and is cooled, and then discharged to the annular first air duct 3, and finally the membrane bubble 7 located at the center of the air ring body is cooled. The air ring body includes an upper air cover 8, an air ring seat 9, a support, an air outlet separation ring 11 and an air protection ring 12. The lower end of the upper air cover 8 is provided with an air inlet 5. The upper air cover 8 is respectively connected to the air ring seat 9 and the support, and an annular cavity is formed inside after the connection. The air ring seat 9 is connected to the air outlet separation ring 11, and after the connection, the annular first air duct 3 is formed with the support. The air protection ring 12 is connected to the support in a lifting manner. It also includes a top cover 28 and a lower cover 29. The top cover 28 is fixed above the upper wind cover 8, and the lower cover 29 is fixed below the wind ring seat 9. The support member includes an intermediate support component 10 and a movable adjustment ring 13. The intermediate support component 10 is connected to the upper wind cover 8. The upper and lower sides of the movable adjustment ring 10 are respectively provided with a thread, and the movable adjustment ring 10 is also provided with a grippable handle 14. The intermediate support component 10 is connected to the movable adjustment ring 10 through the lower thread. By holding the handle 14 and rotating it, the height of the movable adjustment ring 10 can be adjusted, thereby adjusting the air volume and wind speed. The wind protection ring 12 is connected to the movable adjustment ring 10 through the upper thread. The height of the wind protection ring 12 can be adjusted through the thread to adapt to the membrane bubble 7 with different blowing ratios (the direction of lifting and lowering adjustment is as shown in FIG. 1 ). Fig.11As shown, the thread is not drawn in this figure, and the thread can also be replaced by other structures that can realize the lifting and lowering adjustment function. This belongs to the prior art and will not be described in detail in this article). The wind protection ring 12 is provided with a first air leakage hole 15, and an adjustment ring 16 is also sleeved on the corresponding position of the wind protection ring 12, and the adjustment ring 16 is provided with a second air leakage hole 17 (the first air leakage hole 15 can be arranged in multiple rows on the wind protection ring 12 according to the specific situation of the membrane bubble 7, and the adjustment ring 16 can also be arranged in multiple rows accordingly. By rotating the adjustment ring 16, the overlap between the first air leakage hole 15 and the second air leakage hole 17 can be adjusted. The greater the overlap, the less air leaks, and the greater the lifting force). The temperature control device includes a semiconductor refrigeration sheet 4, a first heat sink 18 and a heat dissipation structure, the heat dissipation structure is a water storage chamber 19 and a water circulation component 20, the first heat sink 18 is arranged on one side of the semiconductor refrigeration sheet 4 through a thermally conductive adhesive 21, and the water storage chamber 19 is arranged on the other side of the semiconductor refrigeration sheet 4 through a thermally conductive adhesive 21 (the thermally conductive adhesive 21 can also be replaced with other heat-conducting media according to actual conditions, which belongs to the prior art and will not be described in detail in this article), the top cover 28 and the lower cover 29 are both provided with a hole 32, and the connection end 31 of the water storage chamber 19 passes through the hole 32 and is connected to the water circulation component arranged outside the air ring body The components 20 are interconnected. When the wind in the air chamber passes through the cooling labyrinth air duct 6 formed between the first heat sinks 18 of the two sets of temperature control devices, the semiconductor refrigeration sheet 4 will cool it. During operation, the temperature of the semiconductor refrigeration sheet 4 gradually rises. At this time, the water in the water storage chamber 19 absorbs heat from the semiconductor refrigeration sheet 4, and the water circulation component 20 circulates and cools the water after the heat absorption, so that it can continuously cool the semiconductor refrigeration sheet 4, so that the semiconductor refrigeration sheet 4 can work normally (the water circulation component can be a water pump or other component that can play a water circulation function, which belongs to the prior art and will not be described in detail in this article). It also includes a positioning ring 22 and a heat insulation sheet 30. The positioning ring 22 is connected to the air ring seat 9. The temperature control device on the lower side of the annular cavity is arranged on the positioning ring 22, which is used to support and position the temperature control device. The heat insulation sheet 30 is arranged on the inner wall of the annular cavity, and the temperature control device and the heat insulation sheet 30 are interconnected.

[0054] Figure 5-Figure 17 The second embodiment of the present invention is shown; compared with the first embodiment, the difference is that it also includes a downwind plate 23, which is arranged below the air outlet dividing ring 11, and the air outlet dividing ring 11 is correspondingly provided with ventilation holes 24, and an annular second air duct 25 is formed between the downwind plate 23 and the air outlet dividing ring 11, and a part of the wind of the annular first air duct 3 enters the annular second air duct 25 from the ventilation holes 24, thereby pre-cooling the membrane bubble 7.

[0055] Figure 18-19The third embodiment of the present invention is shown; compared with the second embodiment, the difference is that the first heat sinks 18 of the two sets of temperature control devices are interconnected to form an internal hollow diverter 33, and the diverter 33 can increase the contact area between the wind and the semiconductor refrigeration plate 4, enhance the exchange between them, and at the same time enable the air to evenly and smoothly enter the cooling maze air duct 6 for cooling.

[0056] Fig. 20 The fourth embodiment of the present invention is shown; compared with the third embodiment, the difference is that the heat dissipation structure of the temperature control device is a second heat sink and an air heat dissipation component, the first heat sink 18 is arranged on one side of the semiconductor refrigeration sheet 4 through the thermal conductive adhesive 21, the second heat sink 26 is arranged on the other side of the semiconductor refrigeration sheet 4 through the thermal conductive adhesive 21, and an air heat dissipation component 27 is correspondingly arranged near the second heat sink 26 (the air heat dissipation component 27 can be a heat dissipation fan or other air-cooled components with similar functions, which belongs to the prior art and will not be elaborated in this article), through the air heat dissipation component 27, the semiconductor refrigeration sheet 4 after absorbing heat can be continuously cooled.

[0057] The working process and principle of the present invention are roughly as follows: when the film bubble is extruded from the die of the machine head, it is first cooled by the cooling air ring, and then the film pulling work is completed by the traction mechanism (the machine head and the traction mechanism are other components of the film blowing machine, which belong to the prior art and will not be described in detail in this article). When the film bubble gradually moves upward from the bottom of the air ring body, the air supply device supplies air to the air chamber through the air inlet nozzle. This wind will flow into the cooling maze air duct from the air inlet at the lower end of the upper air cover. After being cooled by the semiconductor refrigeration plates of the temperature control devices on the upper and lower sides, the wind is discharged from the annular first air duct (part of the wind will flow into the annular second air duct through the ventilation holes and be discharged from the annular second air duct. The direction of the wind is as follows Fig.21 As shown), the exhausted wind will cool the membrane bubble. When the blowing ratio of the membrane bubble to be cooled is different, the required lifting force is also different. At this time, the lifting force can be changed by adjusting the movable adjustment ring, the wind protection ring or the adjustment ring (the adjustment principle belongs to the prior art and will not be elaborated in this article) to avoid shaking or other unstable problems of the membrane bubble, so that the cooling work can proceed normally. At the same time, the heat absorbed by the semiconductor refrigeration plate will be dissipated through the heat dissipation structure, so that the semiconductor refrigeration plate can continuously cool the wind sent into the wind chamber.

[0058] It should be noted that the terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present application. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field. The words "first", "second" and similar words used in the specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Unless otherwise specified, the words "inside", "outside", "upper", "lower" and the like are only for the convenience of explanation and are not limited to a position or a spatial orientation.

[0059] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. An automatic cooling air ring, characterized in that: It comprises an air ring body and an air chamber, wherein an annular cavity and an annular first air duct are formed inside the air ring body, two sets of temperature control devices with semiconductor refrigeration sheets are respectively arranged on the upper and lower sides of the annular cavity, one end of the temperature control device is arranged at the air inlet of the air ring body, the air inlet is connected to the air chamber, and the other end is connected to the annular first air duct, after the wind of the air chamber enters from the air inlet, it passes through the cooling maze air duct formed between the two sets of temperature control devices, and is cooled, and then is discharged to the annular first air duct, and finally the film bubble is cooled down; the temperature control device comprises a semiconductor refrigeration sheet, a first heat sink and a heat dissipation structure, one side of the semiconductor refrigeration sheet is connected to the first heat sink, and the other side is connected to the heat dissipation structure, the wind of the air chamber passes through the cooling maze air duct formed between the first heat sinks of the two sets of temperature control devices, and is temperature-controlled by the semiconductor refrigeration sheet, and at the same time, the heat dissipation structure cools the film bubble after absorbing heat. The semiconductor refrigeration plate continuously dissipates heat; the air ring body includes an upper air cover, an air ring seat, a support, an air outlet separation ring and an air protection ring, the air inlet is arranged at the lower end of the upper air cover, the upper air cover is respectively connected to the air ring seat and the support, and an annular cavity is formed inside after the connection, the air ring seat is connected to the air outlet separation ring, and after the connection, an annular first air duct is formed with the support, and the air protection ring is connected to the support in a liftable manner; the support includes an intermediate support assembly and a movable adjustment ring, the intermediate support assembly is connected to the upper air cover, and lifting and adjusting structures are respectively provided on the upper and lower sides of the movable adjustment ring, the intermediate support assembly is connected to the movable adjustment ring through the lifting and adjusting structure on the lower side, and the air protection ring is connected to the movable adjustment ring through the lifting and adjusting structure on the upper side; it also includes a positioning ring, the positioning ring is connected to the air ring seat, and the temperature control device on the lower side of the annular cavity is arranged on the positioning ring.

2. The automatic cooling air ring according to claim 1, characterized in that: The first heat sinks of the two sets of temperature control devices are interconnected to form a hollow diverter, which is used to increase the contact area between the wind and the refrigeration fins and enhance the exchange between them, while allowing the air to evenly and smoothly enter the cooling maze air duct for cooling.

3. An automatic cooling air ring according to claim 1 or 2, characterized in that: The heat dissipation structure comprises a heat exchanger and a liquid refrigerant. One side of the heat exchanger is connected to a semiconductor refrigeration sheet, and the other side is connected to the liquid refrigerant.

4. An automatic cooling air ring according to claim 1 or 2, characterized in that: The heat dissipation structure comprises a second heat sink and an air heat dissipation component. One side of the second heat sink is connected to the semiconductor refrigeration plate, and the other side is provided with an air heat dissipation component.

5. The automatic cooling air ring according to claim 1, characterized in that: It also includes a lower air duct plate arranged on the air outlet separation ring, the air outlet separation ring is provided with ventilation holes, and an annular second air duct is formed between the lower air duct plate and the air outlet separation ring. A part of the wind in the annular first air duct enters the annular second air duct from the ventilation holes, thereby pre-cooling the membrane bubble.

6. An automatic cooling air ring as claimed in claim 5, characterized in that: The cooling labyrinth air duct is a single arc cooling labyrinth air duct.

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