JP2024032207A - Heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating apparatus that can efficiently cool heated components.

SOLUTION: A heating apparatus includes a first heating portion, a first element unit that drives the first heating portion, a first heat sink disposed in the first element unit, a fan that blows air, an air path unit that forms the direction of air from the fan, a casing that accommodates the first heating portion, the first element unit, the first heat sink, and the air path unit, and has an exhaust port at the rear of the apparatus, and the air path unit includes a first air path 35 that guides air from the fan, and a second air path 36 that intersects with the first air path and extends toward the rear, and the first heat sink is disposed in the second air path.

SELECTED DRAWING: Figure 6

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to heating equipment.

Patent Document 1 discloses a heating cooker that cools a plurality of inverter boards. This heating cooker includes a plurality of heating coils, an inverter board equipped with an inverter circuit that supplies alternating current to each heating coil, and a cooling intake fan for taking in air from an intake port formed at the rear. Equipped with. According to this heating cooker, the air taken in by the intake fan from the intake port is blown directly to the inverter board, thereby cooling the inverter board that has generated heat.

Japanese Patent Application Publication No. 2008-59985

The present disclosure provides a heating device that can efficiently cool heating components.

The heating device according to the present disclosure includes a first heating section, a first element unit that drives the first heating section, a first heat sink disposed in the first element unit, a fan for blowing air, and the fan. A casing that accommodates an air channel unit that forms a direction of airflow from the device, the first heating section, the first element unit, the first heat sink, and the air channel unit, and has an exhaust port at the rear of the device. The air path unit includes a first air path that guides air from the fan, and a second air path that intersects the first air path and extends toward the rear. The first heat sink is disposed in the second air passage.

According to the heating device of the present disclosure, the air sent from the fan is sent to the second air path that intersects with the first air path and extends rearward via the first air path of the air path unit. Since the air is brought into contact with the first heat sink provided in the second air path and then sent to the rear exhaust port, the first heat sink can be efficiently cooled.

A perspective view of an IH cooker in Embodiment 1 Top view of the inside of the IH cooker in Embodiment 1 Top view of the inside of the IH cooker in Embodiment 1 Electrical configuration diagram of the control board inverter circuit section for left and right coils in Embodiment 1 Top view of the inside of the IH cooker in Embodiment 1 Top view of the inside of the IH cooker in Embodiment 1

Hereinafter, embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of well-known matters or redundant explanations of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art.

The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

(Embodiment 1)
Embodiment 1 will be described below using FIGS. 1 to 6.

[1-1. composition]
[1-1-1. Overall configuration of IH cooker]
Hereinafter, the terms "front", "back", "left", and "right" used in the text refer to the positional relationship with respect to the front of the device body.

In FIG. 1, the IH cooker is comprised of a top unit 1 and a main unit 2. The top unit 1 includes a glass plate 3, a frame 4, and an operation interface 5. The glass plate 3 has a rectangular shape and is made of heat-resistant glass such as crystallized glass. The glass plate 3 is arranged on the top surface of the IH cooker, and a cooking container such as a pot is placed on the top surface. Further, the frame 4 is used to connect the glass plate 3 to the main unit 2. This frame 4 is made of a metal material and surrounds the outer periphery of the glass plate 3. Furthermore, the operation interface 5 is arranged in front of the top unit 1 and accepts heating operations of the IH cooker. The operation interface 5 is appropriately selected from mechanical switches, electrostatic switches, touch switches, touch liquid crystals, and the like.

With further reference to FIG. 2, the main unit 2 includes an upper housing 6, a lower housing 7, a left coil unit 8 that is a second heating section, a right coil unit 9 that is a first heating section, and a second heating section. It includes a rear coil unit 10 which is three heating parts, a fan 11, a control board 12 for left and right coils, a control board 13 for rear coils, and an air passage unit 14. The upper housing 6 houses a left coil unit 8, a right coil unit 9, a rear coil unit 10, a fan 11, a control board 12 for left and right coils, a control board 13 for rear coils, and an air path unit 14. do. This upper housing 6 has a box shape with a hollow interior and is made of a metal material. On the other hand, the lower housing 7 also has a hollow box shape, is made of a metal material, and is fixed to the upper housing 6 with screws or the like. This lower housing 7 accommodates a grill unit 15 (FIG. 1). The grill unit 15 is disposed biased to either the left or right side within the housing. In this embodiment, they are arranged biased to the left when viewed from the front of the drawing. That is, the center of the lower housing 7 in the left-right direction is located to the left of the center of the IH cooker in the left-right direction. This grill unit 15 is equipped with a heater, and performs heating cooking using the heater. Although the grill unit 15 is disposed biased to the left side when viewed from the front in this embodiment, the grill unit 15 is not limited to this, and may be disposed biased to the right side when viewed from the front. It may be arranged in the central part within the housing.

The left coil unit 8, right coil unit 9, and rear coil unit 10 each heat a pot placed on the glass plate 3 by induction heating. The left coil unit 8 is arranged on the front left side when viewed from the top. The right coil unit 9 is arranged on the front right side when viewed from the top. The rear coil unit 10 is arranged at the rear between the left coil unit 8 and the right coil unit 9 when viewed from the top. Although not particularly shown, the left coil unit 8, right coil unit 9, and rear coil unit 10 are each equipped with a coil, a ferrite, a case that accommodates the ferrite and the coil, and a temperature sensor, similarly to the known technology. The left and right coil control board 12 controls heating of the left coil unit 8 and the right coil unit 9. The left and right coil control board 12 is disposed below the left coil unit 8 and right coil unit 9, and is biased to the left when viewed from the top. Note that the specific configuration of the left and right coil control boards 12 will be described later. Further, the rear coil control board 13 controls heating of the rear coil unit 10. After this, the coil control board 13 is the left and right coil control board 12 when viewed from the top.
It is located on the right side of the fan 11 and behind the fan 11.

The fan 11 cools the left coil unit 8, the right coil unit 9, the rear coil unit 10, the left and right coil control board 12, and the rear coil control board 13. This fan 11 is placed in front of the right side when viewed from the top. The air passage unit 14 guides the wind generated from the fan 11. This air passage unit 14 is arranged on the left side of the fan 11 when viewed from the top. The air passage unit 14 is provided with a plurality of inner walls within the unit so that the air from the fan 11 can be branched. The cooling air generated by this fan 11 cools various parts, flows from the front to the back of the housing, and is discharged through the exhaust port 16 arranged at the rear of the housing. The exhaust port 16 has a first exhaust port 17 and a second exhaust port 18, the first exhaust port 17 is located at the rear right when viewed from the top, and the second exhaust port 18 is located at the rear right when viewed from the top. is placed at the rear left.

[1-1-2. Configuration of control board for left and right coils]
As shown in FIG. 3, the left and right coil control board 12 includes a rectifier section 19, a left coil unit control section 20, and a right coil unit control section 21. Further, an electrical configuration diagram of the left and right coil control board 12 is shown in FIG. The rectifier section 19, the left coil unit control section 20, and the right coil unit control section 21 each include a first heat sink 22, a second heat sink 23, and a third heat sink 24. Note that the heat sink is used to radiate heat accumulated in components that generate heat during induction heating. The rectifier section 19 includes a first diode bridge 25 and a third heat sink 24 . The amount of heat generated by the rectifier section 19 is smaller than the amount of heat generated by each of the first element unit and the second element unit, which will be described later. The first diode bridge 25 rectifies the AC power supply of 200V and converts it into DC. The first diode bridge 25 is located in the center of the left and right coil control board 12, and is arranged on the side surface of the third heat sink 24. The third heat sink 24 is arranged at the center of the left and right coil control board 12.

The right coil unit control section 21 controls a first IGBT 26, a second IGBT 27, a first heat sink 22, a first coil 28 as a first coil component, and a plurality of right capacitors 29 for the right coil unit 9. Be prepared. Note that the IGBT is a switching element used to drive an inverter circuit. The first IGBT 26 and the second IGBT 27 are used to convert input power into high frequency power. Here, the first IGBT 26 and the second IGBT 27 constitute a first element unit. A first heat sink 22 is attached to the first IGBT 26 and the second IGBT 27, and accumulated heat is radiated through the first heat sink 22. The first heat sink 22 is arranged on the right side of the left and right coil control board 12 and on the left side of the fan 11.

The first heat sink 22 is divided into a front side and a rear side, and a space is formed between the front side and the rear side. The first IGBT 26 is attached to the right side of the first heat sink 22 on the front side, and the second IGBT 27 is attached to the right side of the first heat sink 22 on the rear side. The first IGBT 26 and the second IGBT 27 are arranged on the right side of the first heat sink 22 so as to be separated from the third IGBT 30 and the fourth IGBT 31. The first coil 28 is used for noise removal and is arranged at the back right of the first heat sink 22. The plurality of right capacitors 29 are used as smoothing/resonant capacitors and are arranged on the right side of the first heat sink 22 .

The left coil unit control section 20 includes a third IGBT 30 for the left coil unit 8, a fourth IGBT 31, a second heat sink 23, a second coil 32, and a plurality of left capacitors 33. Here, the third IGBT 30 and the fourth IGBT 31 constitute a second element unit. The second coil 32, which is a second coil component, is used for noise removal. Since the functions and structures common to the right coil unit control section 21 are the same, their explanations will be omitted. The second heat sink 23 is arranged on the left side of the first heat sink 22 and on the right side of the third heat sink 24.

The second heat sink 23 is divided into a front side and a rear side, and a space is formed between the front side and the rear side. The third IGBT 30 is attached to the left side of the second heat sink 23 on the front side, and the fourth IGBT 31 is attached to the left side of the second heat sink 23 on the rear side. The second coil 32 is provided on the downstream side of the first heat sink 22 in the direction in which the air is blown from the fan 11 , and is located closer to the first heat sink 22 than the first coil 28 . The fan 11 is disposed on the upstream side in the direction of the wind blowing from the fan 11. That is, the first heat sink 22, the second coil 32, and the first coil 28 are provided in this order from the upstream side to the downstream side in the air blowing direction of the second air path 36. That is, the second coil 32 is disposed immediately downstream of the first heat sink 22 and closer to the first heat sink 22 than the first coil 28 . The plurality of left capacitors 33 are arranged on the left side of the second heat sink 23 or on the right side of the third heat sink 24.

Note that the third coil 34 is placed at the back left of the board and is used for noise removal.

[1-1-3. Configuration of control board for rear coil]
As shown in FIG. 5, the rear coil control board 13 includes a second diode bridge 50, a fourth heat sink 51 for the second diode bridge 50, a fifth IGBT 52, a sixth IGBT 53, a fifth IGBT 52, and a fourth heat sink 51 for the second diode bridge 50. It includes a fifth heat sink 54 for the six IGBTs 53, a fourth coil 55, a fifth coil 56, and a plurality of rear capacitors 57.

The arrangement of each component is as follows: the second diode bridge 50 is attached to the left side of the fourth heat sink 51. The fifth coil 56 is arranged in front of the left side of the rear coil control board 13, and the fourth heat sink 51 is arranged behind the fifth coil 56. The fifth IGBT 52 and the sixth IGBT 53 are attached to the right side of the fifth heat sink 54. The fifth heat sink 54 is arranged at the front center of the rear coil control board 13, and a plurality of rear capacitors 57 are arranged on the right side thereof. The fourth coil 55 is arranged on the left rear side of the rear coil control board 13.

[1-1-4. Configuration of air channel unit]
In FIG. 6, the air passage unit 14 includes a housing structure having a plurality of inner walls, and includes a first air passage 35, a second air passage 36 branching from the first air passage 35, and a second air passage 36 branching from the first air passage 35. A third air path 37, a fourth air path 38 and a fifth air path 39 branching from the first air path 35 are formed.
Next, each air path will be explained.

The first air passage 35 is directly connected to the outlet of the fan 11 and sends the air from the fan 11 horizontally from right to left. That is, the first air path 35 is provided in a linear shape from the right side, which is one end of the apparatus body, toward the center of the apparatus body, along the direction of the air blown out from the outlet of the fan 11.
The second air path 36, the third air path 37, the fourth air path 38, and the fifth air path 39 are directed from the upstream side to the downstream side in the direction of the wind moving in the first air path 35. , are formed to gradually branch off from the first air path in this order. First of all, the first inner wall 40 in the air passage unit 14 branches the second air passage 36 from the first air passage 35 . Next, the third air path 37 branches from the first air path 35 due to the second inner wall 41 of the first air path 35 whose width is narrowed. Further, the third inner wall 42 of the first air passage 35 whose width is further narrowed allows the first air passage 35 to branch into a fourth air passage 38 and a fifth air passage 39.

In addition, each inner wall (first inner wall 40, second inner wall 41, third inner wall 42) in each air passage (second air passage 36 to fifth air passage 39) and the opposing inner surface on the front side of the air passage unit 14 The distance between the air passages is made smaller from the upstream side to the downstream side in the air blowing direction, and the width of each air passage is set. Specifically, the distance between the first inner wall 40 and the opposing inner surface in the first air path 35 is larger than the distance between the second inner wall 41 and the opposing inner surface in the first air path 35; The distance between the second inner wall 41 and the opposing inner surface in the first air path 35 is set larger than the distance between the third inner wall 42 and the opposing inner surface in the first air path 35.

Furthermore, each air path will be explained.
The second air passage 36 crosses the first air passage 35 to send wind backward, and the first heat sink 22 is disposed within the second air passage 36.

Further, the third air passage 37 is provided apart from the fan 11 with respect to the second air passage 36, and is arranged on the left side of the second air passage 36. This third air path 37 intersects with the first air path 35 to send wind backward, and the second heat sink 23 is disposed within this third air path 37.

Furthermore, the fourth air passage 38 is provided apart from the fan 11 with respect to the third air passage 37, and is arranged on the left side of the third air passage 37. A third heat sink 24 is arranged within this fourth air passage 38 .

Finally, the fifth air passage 39 is provided apart from the fan 11 with respect to the fourth air passage 38, and sends air to the back left of the housing.

Note that, as shown in FIG. 5, a sixth air path 58 may be formed on the back side of the fan 11 in the air path unit 14. Specifically, the sixth air passage 58 is provided with an air outlet on the surface corresponding to the rear coil control board 13 of the air passage unit 14, and air is blown toward the rear coil control board 13 through this air outlet. . Inside the sixth air path 58, each component of the rear coil control board 13 (the second diode bridge 50, the fourth heat sink 51, the fifth IGBT 52, the sixth IGBT 53, the fifth heat sink 54, the fourth coil 55, and the fifth A coil 56 and a plurality of rear capacitors 57) are arranged.

[1-2. motion]
The operation based on the above configuration will be explained below.
Here, the operation of the cooling air during induction heating using the left and right coil control board 12 will be explained. The inverter circuit on the left and right coil control board 12 is driven to generate a high frequency magnetic field from the heating coil. Then, a pot placed on the top surface of the glass plate 3 is heated by electromagnetic induction. At this time, each element component (IGBT, coil, capacitor) on the left and right coil control board 12 generates heat as a result of the heating operation. Note that heat is transmitted from the IGBT that generates heat, and the heat sink also generates heat.

At this time, the first air passage 35 blows air from the outlet of the fan 11 in a horizontal direction from right to left, as described above. The wind sent into the first air path 35 is gradually branched into a second air path 36, a third air path 37, a fourth air path 38, and a fifth air path 39 by the air path unit 14. sent.

In the second air path 36, the air sent from the first air path 35 connects the first IGBT 26 disposed in the second air path 36 and the second The IGBT 27, the first heat sink 22, the second coil 32, the first coil 28, and the plurality of right capacitors 29 are cooled.

In the third air path 37, the air sent from the first air path 35 connects the third IGBT 30 disposed in the third air path 37 and the fourth IGBT 30 from the upstream side to the downstream side in the air blowing direction. The IGBT 31 and the second heat sink 23 are cooled.

Further, in the fourth air path 38, the air sent from the first air path 35 causes a first diode bridge 25 arranged in the fourth air path 38 from the upstream side to the downstream side in the air blowing direction, The third heat sink 24 and the plurality of left capacitors 33 are cooled.
Further, in the fifth air path 39, the third coil 34 disposed in the fifth air path 39 is cooled by the air sent from the first air path 35.

In this case, the components of the right coil unit control section 21 (the first IGBT 26, the second IGBT 27, the first heat sink 22, the first coil 28, and the plurality of right capacitors 29) are not connected to the fan 11. By arranging them all in the second air passage 36, relatively fresh cooling air can be supplied, and a cooling effect can be expected.

On the other hand, the components of the left coil unit control section 20 (the third IGBT 30, the fourth IGBT 31, the second heat sink 23, the second coil 32, and the plurality of left capacitors 33) are connected to the right coil with respect to the fan 11. It is arranged at a distance from the component parts of the unit control section 21, and is not arranged in the same air path.
By distributing and arranging the air passages in the second air passage 36, the third air passage 37, and the fourth air passage 38, cooling is performed separately in each air passage.

Then, the wind passing through the second air passage 36, the third air passage 37, and the fourth air passage 38 cools each component, and then flows to the first exhaust port 17 at the back right of the casing, and exits the casing. is discharged. After cooling the coil 34, the wind passing through the fifth air passage 39 flows to the second exhaust port 18 at the back left of the housing, and is discharged outside the housing.

Here, the operation of the cooling air during induction heating using the rear coil control board 13 will also be explained. Similarly to the left and right coil control board 12, each component (second diode bridge 50, fourth heat sink 51, fifth IGBT 52, sixth IGBT 53, fifth heat sink 54, fourth coil 55) is , the fifth coil 56, and the plurality of rear capacitors 57) generate heat.

In this sixth air path 58, the air sent from the air outlet causes each component (second diode bridge 50, second diode bridge 50, The fourth heat sink 51, the fifth IGBT 52, the sixth IGBT 53, the fifth heat sink 54, the fourth coil 55, the fifth coil 56, and the plurality of rear capacitors 57) are cooled. After the wind passing through the sixth air passage 58 cools each of the above-mentioned components, it flows to the first exhaust port 17 at the back right of the housing and is discharged to the outside of the housing.

[1-3. effect]
According to the IH cooker of the present disclosure, the air sent from the fan 11 is transferred to each of the first air passage 35 to the fifth air passage 39 that intersect with the first air passage 35 of the air passage unit 14 and extend rearward. By sending it into the air passages, it comes into contact with the components placed in each air passage and cools them, and then it is sent to the rear exhaust port, which has the effect of efficiently cooling each component placed on each air passage. .

Furthermore, the cooling effect when a pot is inductively heated by the left coil unit 8 using the IH cooker of the present disclosure will be described. When heating with this left coil unit 8, the third IGBT 30 for the left coil unit 8 of the left coil unit control section 20, the fourth IGBT 31, the second heat sink 23, the second coil 32, and a plurality of left The capacitor 33 generates heat.

Here, if all the components are arranged in the same air path, the heat accumulated after cooling the third IGBT 30, the fourth IGBT 31, the second heat sink 23, and the plurality of left capacitors 33 will be However, it comes into contact with the second coil 32 located at the rear, which is the downstream side in the air blowing direction, and there is a possibility that the second coil 32 cannot be sufficiently cooled. On the other hand, according to the IH cooker of the present disclosure, the second coil 32 is arranged in the second air path 36, while the third IGBT 30, the fourth IGBT 31, the second heat sink 23, Since the plurality of left capacitors 33 are distributed in the third air passage 37, the cooling air moving in the second air passage 36 comes into contact with the second coil 32, and the third IGBT 30, the fourth IGBT 31, and the third IGBT 31 are connected to each other. Since the cooling air moving in the third air passage 37 comes into contact with the second heat sink 23 and the plurality of left capacitors 33, each component can be cooled individually, and the overall cooling efficiency is expected to be improved.

(Other embodiments)
In the first embodiment, a configuration including a control board for left and right coils and a control board for a rear coil has been described, but the present invention is not limited to this, and can also be applied to a configuration including only a control board for left and right coils, for example.
The present disclosure is not limited to IH heating cookers, but can also be applied to other heating devices.
Note that the above-described embodiments are for illustrating the technology of the present disclosure, and therefore various changes, substitutions, additions, omissions, etc. can be made within the scope of the claims or equivalents thereof.

The present disclosure is applicable to heating devices such as induction heating cookers.

1 Top unit 2 Main unit 3 Glass plate 4 Frame 5 Operation interface 6 Upper housing 7 Lower housing 8 Left coil unit 9 Right coil unit 10 Rear coil unit 11 Fan 12 Left and right coil control board 13 Rear coil control board 14 Wind Channel unit 15 Grill unit 16 Exhaust port 17 First exhaust port 18 Second exhaust port 19 Rectifier section 20 Left coil unit control section 21 Right coil unit control section 22 First heat sink 23 Second heat sink 24 Third heat sink 25 First Diode bridge 26 1st IGBT
27 Second IGBT
28 First coil 29 Plural right capacitors 30 Third IGBT
31 Fourth IGBT
32 Second coil 33 Plural left capacitors 34 Third coil 35 First air path 36 Second air path 37 Third air path 38 Fourth air path 39 Fifth air path 40 First inner wall 41 Second inner wall 42 Third inner wall 50 Second diode bridge 51 Fourth heat sink 52 Fifth IGBT
53 Sixth IGBT
54 Fifth heat sink 55 Fourth coil 56 Fifth coil 57 Multiple rear capacitors 58 Sixth air path

Claims (10)

a first heating section; a first element unit that drives the first heating section;
a first heat sink disposed in the first element unit;
A fan for blowing air,
an air path unit that forms the direction of air from the fan;
A casing that accommodates the first heating section, the first element unit, the first heat sink, and the air path unit and has an exhaust port at the rear of the device,
The air path unit is
comprising a first air path that guides air from the fan, and a second air path that intersects with the first air path and extends toward the rear,
A heating device characterized in that the first heat sink is arranged in the second air path. a second heating section;
a second element unit that drives the second heating section;
a second heat sink disposed in the second element unit;
The air path unit is
a third air path that intersects with the first air path and extends toward the rear, and is provided apart from the fan with respect to the second air path;
The heating device according to claim 1, wherein the second heat sink is arranged in the third air path. Equipped with a rectifier that rectifies AC power and converts it to DC.
The air path unit is
a fourth air path that intersects with the first air path and extends toward the rear, and is provided apart from the fan with respect to the third air path;
The heating device according to claim 2, wherein the rectifier is arranged in the fourth air path. The heating device according to claim 3, wherein the rectifier has a smaller calorific value than each of the first element unit and the second element unit. The first heating section includes a first coil component, the second heating section includes a second coil component,
The heating device according to claim 2, wherein the second coil component is arranged in the second air path, and is provided on the downstream side of the first heat sink in the direction in which the air is blown from the fan. The first coil component is arranged in the second air path, and is provided on the downstream side in the air blowing direction with respect to the first heat sink, and on the downstream side in the air blowing direction with respect to the second coil component. is,
The first heat sink, the second coil component, and the first coil component are provided in this order from the upstream side to the downstream side in the air blowing direction of the second air path. Heating equipment as described. The second air path is provided branching from the first air path,
3. The third air path is provided to branch from the first air path on the downstream side in the blowing direction of the branch position of the second air path in the first air path. heating equipment. The air passage unit is provided with a first inner wall that branches air in the first air passage and guides it to the second air passage, and is provided on the downstream side of the first inner wall in the air blowing direction, and a second inner wall that branches air in the passage and guides it to the third air passage;
The heating device according to claim 2, wherein a distance between the second inner wall and the opposing inner surface in the first air path is smaller than a distance between the first inner wall and the opposing inner surface in the first air path. The first heating section includes a first coil component, the second heating section includes a second coil component,
The distance between the first heating section and the fan is smaller than the distance between the second heating section and the fan,
The first element unit, the first heat sink, and the first coil component of the first heating section are arranged in the second air path,
Claim 2, wherein the second element unit and the second heat sink of the second heating section are arranged in the third air path, and the second coil component of the third heating section is arranged in the second air path. Heating equipment as described. The first heating section includes a first coil component, the second heating section includes a second coil component,
A grill is provided inside the housing, the fan is disposed on a different side of the interior of the housing with respect to the grill, and the distance between the first heating section and the grill is equal to the distance between the second heating section and the grill. greater than the distance between
The first element unit, the first heat sink, and the first coil component of the first heating section are arranged in the second air path,
Claim 2, wherein the second element unit and the second heat sink of the second heating section are arranged in the third air path, and the second coil component of the third heating section is arranged in the second air path. Heating equipment as described.

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