JPH01181060A - Ice-making device for refrigerating chamber and the like - Google Patents

Abstract

PURPOSE:To shorten a clear ice-making time and to make ordinary ice in a short time with high efficiency, by a method wherein a vent hole is formed in a heating plate, a temperature sensor is provided in the back space of the heating plate, a partition plate is placed below 8 cooling plate, and first and second ventilation flues are formed. CONSTITUTION:An ambient temperature in an icemaking chamber 22 is detected through a vent hole 26 formed in a heating plate 27 by means of a temperature sensor 28. The starting of energization of a heating device 25 is more delayed than the starting of ice-making until temperature by the temperature sensor attains a predetermined value, and cooling is performed without cooling until the temperature of water is reduced to approximate 0 deg.C. A door body 29 isolates an influence by external atmosphere on the interior of the ice-making chamber 22. Cool air passing through a first ventilation flue 33 cools a cooling plate 13 to make clear ice by using a first ice-making pan 15. When it flows to the rear after flowing back to the interior of a second ventilation flue 34, a second ice-making pan 16 is cooled from its upper surface to perform making of ordinary ice. A thermal influence by water in the second ice-making pan 16 is isolated by a partition plate 32, and the cooling force of the cooling plate 13 is not lowered. Generated steam is also shut off by the partition plate 32, and the cooling force of the cooling plate 13 is prevented from reduction due to frosting and icing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ice-making device that is disposed in a freezer compartment of a refrigerator and is particularly capable of producing transparent ice.

Conventional technology Conventionally, in household refrigerators, etc., an ice making device that stores an ice tray is placed in one section of the freezer compartment, and the water in the ice tray is frozen by the cooling effect of the cold air flowing through the ice making device to make ice. The generation of is carried out uniformly.

However, with this ice generation method, when ice is generated, the water in the ice tray progresses from the contact surface between the ice tray and the water and the contact surface between the cold air and water to the center. As a result, gaseous components and impurities dissolved in the water are trapped in the center of the ice, resulting in opaque ice with a cloudy center, which is sensually suitable for beverages such as whisky. It wasn't.

Therefore, there has been a need for transparent ice since the past, and for example, in 1986,
This method is known from Japanese Patent No. 9779 and is shown in FIGS. 7 to 9.

The basic contents will be explained below with reference to FIGS. 7 to 9.

Reference numeral 1 denotes a refrigerator body, which is divided by a partition wall 2 into a freezing compartment 3 at the top and a refrigerating compartment 4 at the bottom. 5 is a cooler for the refrigeration cycle, and 6 is a blower for forced ventilation, which are connected to the freezer compartment 3, respectively.
is located on the back of the.

7 is an ice making device placed at the bottom of the freezer compartment 3;
A box body 7a is framed, and a first ice-making compartment 8 for producing transparent ice is provided in the upper stage, and a second ice-making compartment 9 for producing normal ice is provided in the lower stage.

The first ice-making chamber 8 is surrounded by a heat insulating material 10 on the outer wall except for the bottom and front surface, and there is an aluminum heating plate 12 on the top surface with a heater 11 on the back surface, and an aluminum heating plate 12 on the bottom surface. Cooling plates 13 made of aluminum are respectively arranged. Reference numeral 14 indicates a ventilation passage formed on the upper part of the cooling plate 13, and reference numeral 15 and 16 indicate a ventilation passage formed in the upper part of the cooling plate 13, and reference numerals 15 and 16 indicate the first ice making compartment 8 and the second ice making compartment 9, respectively.
ice tray and a second ice tray. Further, 17 is a discharge duct for forcing the cold air cooled by the cooler 6 into the ice making device 7 by the blower 6, and the discharge duct 17 is used to forcefully ventilate the cold air cooled by the cooler 6 to the ice making device 7. It communicates with the inside of the second ice making chamber 9. Reference numeral 19 denotes a return duct for returning cold air discharged into the freezer compartment 3 to the cooler 5. Further, reference numeral 2o is a transparent ice making switch, which is configured so that once the switch is turned on, the heater 11 is energized for a predetermined period of time.

In this configuration, the cold air cooled by the cooler 6 is supplied to the freezer compartment 3 and the refrigerator compartment 4 by the forced draft action of the blower 6, and at the same time is supplied to the second ice making device 7 through the discharge port 18 of the discharge duct. It is discharged into the ice making compartment 9 and the ventilation path 14. The cold air guided into the second ice-making compartment 9 directly cools the second ice-making tray 16, and the water inside is sequentially removed from the water surface and the surface of the remaining ice tray that comes into contact with the second ice-making tray 16. Freezes to produce regular ice. However, as mentioned above, the ice produced in this way is cloudy and does not become transparent.

On the other hand, the cold air guided into the ventilation passage 14 cools the cooling plate 13. Therefore, in order to make transparent ice, the user stores the first ice tray 16 filled with water in the first ice making compartment 8 and turns on the ice making switch 2o. 11 starts the heating action via the heating plate 12, and cooling, ie freezing action, starts from the lower surface via the cooling plate 13 by cold air flowing through the ventilation passage 14.

Here, the outer wall of the first ice making chamber 8 is covered with a heat insulating material 1o, so that it is not affected by the cooling effect from the freezing chamber 3, and the freezing action progresses in one direction from the bottom surface to the top surface. Since this freezing effect is indirect cooling via the cooling plate 13 and also includes the heating effect by the heater 11 whose capacity is set in advance, the freezing speed becomes sufficiently slow. Therefore, the speed at which the frozen surface of the ice moves is slower than the upward diffusion speed of the gaseous components in the water, and the dissolved concentration of the gaseous components in the water near the frozen surface becomes diluted, reducing the chance of bubble generation. Even if bubbles still form, the freezing speed is slow, so the bubbles will not be trapped in the water.

In this way, if the freezing rate is controlled to approximately 3 tm/n or less, the gaseous components in the water will be degassed from the surface of the frozen ice to the outside air, and the finally formed ice will contain almost no air bubbles. No clear ice is obtained.

Further, the heater 11 is automatically de-energized after a predetermined time has elapsed, with some margin given to the time required to complete ice making.

Problems to be Solved by the Invention However, this configuration has the following problems.

0) When the heater 11 starts energizing at the same time as the ice making switch 20 is turned on, that is, when the first ice tray 16 filled with water is stored, the water in the first ice tray 16 reaches 0°C. Even during the so-called water state until it reaches 0°C and begins to freeze, the heating action of the schiheater 11 is carried out on the upper surface.
As a result, it takes a longer time to complete ice making, or freezing starts with a very slow cooling effect, so sometimes it takes longer to reach 0.
Even when the temperature reaches ℃, it does not start freezing and remains in the water state.
If a so-called supercooling phenomenon occurs, in which the ice is supercooled to a temperature below b, and if this condition continues for a long time and the return to normal freezing conditions is delayed, air bubbles will disperse and opaque ice will be formed.

(2) Since the front of the first ice-making compartment 8 opens into the freezing compartment 3, the cold air in the freezing compartment 3 acts as a cooling effect on the front part of the stored first ice-making tray 16. Alternatively, instability factors may occur in the freezing conditions for producing transparent ice, such as being affected by outside air heat intrusion due to opening and closing of the door of the freezer compartment 3, resulting in poor transparency.

(3) The cooling plate 13 is cooled by the cold air flowing through the ventilation path 14 to make transparent ice in the first ice tray 16, while the second ice tray 16 is directly cooled to make normal ice at the same time. When the second ice tray 16 is used to make normal ice while the first ice tray 16 is making transparent ice, the temperature of the water in the second ice tray 16 may vary depending on the temperature of the water in the second ice tray 16. Thermal influence affects the cooling plate 13, increasing the temperature of the cooling plate 13 and reducing its cooling capacity, so that the ice-making speed in the first ice-making tray 16 becomes slower than necessary, and the ice-making time becomes longer.

(4) Until the water in the second ice tray 16 freezes, water vapor is generated from the surface of the ice, and the water is transferred to the cooling plate 16.
As a result, the cooling plate 13 is not sufficiently cooled due to frost formation or freezing on the bottom surface of the first ice tray 15.
There was a problem that the ice making time became long.

In addition, problems such as thermal effects on the cooling plate 13 caused by ice making in the second ice tray 16, frost formation, and freezing can be avoided in the ventilation path 1.
4, the cooling plate 13 and the second ice tray 16 are narrow in the height direction.
The closer the distance between the two, the more noticeable it becomes. Therefore, in order to alleviate this tendency, it is possible to make the ventilation passage 14 wider in the height direction, but in this case, the distance between the cooling plate 13 and the second ice tray 16 becomes large, and both can be used simultaneously. It is difficult to cool the ice sufficiently, and both the transparent ice making using the first ice tray 15 and the normal ice making using the second ice tray 16 take a long time.

The present invention solves the above-mentioned problems, and prevents the unnecessary extension of ice-making time and the opacity of ice due to overcooling, and eliminates the influence of the atmosphere outside the ice-making chamber to produce stable, transparent ice. Even if the second ice tray is made, the ice making time of the transparent ice in the first ice tray is not prolonged, and the ice making time of the normal ice in the second ice tray is also prolonged. The aim is to provide ice making equipment that does not require ice making equipment.

Means for Solving the Problems In order to solve the problems, the ice making device such as a refrigerator of the present invention has the following features:
A ventilation hole is formed in a part of the heating plate on the top surface of the ice making chamber where a heating device such as a heater is arranged, and a temperature sensor for controlling the heating device is provided in the space behind the heating plate opposite to this ventilation hole. The front opening of the ice-making compartment is provided with a door that can be opened and closed, and a partition plate is provided below the cooling plate at a predetermined interval, and between the cooling plate and this partition plate, a partition plate is provided that extends from the rear to the front. A first ventilation path is formed between the partition plate and the second ice tray, and a second ventilation path is formed between the partition plate and the second ice tray, communicating with the first ventilation path and flowing from the front to the rear. .

Function According to the above-described configuration, the temperature sensor detects the atmospheric temperature inside the ice-making chamber, which is affected by the water temperature in the ice-making tray, through the ventilation hole provided in the heating plate. Then, for example, the start of energization of the heating device is delayed from the start of ice making until the temperature sensor reaches a predetermined temperature in response to the start of freezing of water. Therefore, cooling is performed without heating until the water reaches approximately 0°C. On the other hand, a door provided at the front opening of the ice-making chamber blocks the influence of external atmosphere into the ice-making chamber. Next, the cold air flowing from the rear to the front in the first ventilation passage cools the cooling plate and makes transparent ice in the first ice tray, and then the second ventilation passage flows from the front to the front. When it is folded back into the road and distributed to the rear, the second ice-making tray is cooled from the top surface to perform normal ice-making. At that time, the second
The heat effect from the water in the ice tray is blocked by the partition plate and does not reach the cooling plate, so the cooling power of the cooling plate does not decrease. In addition, the generated water vapor is blocked by the partition plate and does not directly affect the cooling plate.
The cooling power of the cooling plate does not decrease due to frost formation or freezing.

EXAMPLE Hereinafter, an ice making apparatus such as a refrigerator according to an example of the present invention will be described with reference to FIGS. 1 to 6. Incidentally, the same components as those in the prior art are given the same reference numerals, and detailed explanation thereof will be omitted.

21 is an ice making device provided at the bottom of the freezer compartment 3, and the box body 21
The first one is framed by a and produces transparent ice in the upper layer.
ice making compartment 22, and a second ice making compartment 22 in the lower stage for producing regular ice.
An ice making room 23 is provided.

The first ice-making chamber 22 has an outer wall, except for the bottom and front, surrounded by a heat insulating material 24, and a heater 25 is installed on the back side of the top surface, and a ventilation hole 26 is provided in a section near the center. A heated plate 27 made of aluminum is arranged. 28
A temperature sensor is provided on the back side of the heating plate 27 in a space formed by cutting out a part of the heat insulating plate 24, facing the ventilation hole 26, and controls the energization of the heater 25. 29 is a door provided in the front opening of the first ice making compartment 22 so that it can be opened and closed; 3o is a transparent ice making switch;
31 is a temperature sensor for controlling the temperature of the freezer compartment 3. Reference numeral 32 denotes a partition plate provided below the cooling plate 13 at a predetermined interval, the front end of which is bent upward into an abbreviated shape and abuts against the bottom surface of the cooling plate 13. Reference numeral 33 denotes a first ventilation path formed between the cooling plate 13 and the partition plate 32, and is configured so that cool air flows from the rear to the front of the box body 21&. 34 is the partition plate 23
A second ice tray formed above the second ice tray 16 below the
The first ventilation passage 33 is connected to the first ventilation passage 33 at the front of the box body 21a, and is configured to circulate cold air from the front to the rear. 35 is the first ventilation passage 33 and the second ventilation passage 33;
This is a communication hole formed in front of the partition plate 32 to communicate the ventilation path 34 of the partition plate 32. 36 is the ice making device 2
The duct 17 led to the back side of the first ventilation passage 33
The air supply port 37 is connected to and opens in the second ventilation passage 3.
This is an exhaust port that opens at the rear end of the air conditioner 4 and communicates with the cooler 6. Further, 38 is a compressor of a refrigeration cycle provided at the rear of the lower part of the main body 1.

Next, the electric circuit and control circuit will be explained.

The compressor 38 is connected in parallel with the blower 6 and then connected to a power source via a relay contact 39.

Further, the heater 25 is connected in series with the relay contact 40 and then connected to the power source via the relay contact 39. Next, 41 is a freezing room temperature control device, and temperature sensor 31. Comparison circuit with resistors R1, R2, R3° comparator 42, transistor 43. Relay coil 44
The output of the comparator 42 is connected to the base of a transistor 43. Further, a suction relay coil 44 for opening and closing the relay contact 39 is connected to the collector of the transistor 43. 46 is an ice-making control device, which includes a temperature sensor 2B, a comparison circuit equipped with a R4, R5°R6, =ry parator 46, an ice-making switch 7+30, a tie-q-47, 48, and an AND circuit 4.
9 and transistor 50. Relay coil 51tJfNz
t, and the output of the comparator 46 is connected to the AND circuit 4.
9, the output of the ice making switch 3o is connected to the input of the timer 47, and the output of the timer 47 is connected to the AND circuit 4.
9 is connected to the other input. Here, once the input is applied, the timer 47 becomes Hi after a predetermined time t0 has elapsed.
It is configured to output a signal of gh (hereinafter referred to as "H"). Next, the output of the AND circuit 49 is the timer 48
The reset 7 of the timer 47 is connected to the input of the timer 47 at the same time.
) terminal is also connected. Here, the timer 48 is configured to continue outputting an H'' signal until a predetermined time t has elapsed once the input is applied.

The output of timer 48 is then connected to the vane of transistor 60. Further, a suction relay coil 61 for opening and closing the relay contact 40 is connected to the collector of the transistor 60.

In this configuration, when the temperature of the freezer compartment 3 is higher than a predetermined value, the resistance value RT H1 of the temperature sensor 31 becomes small and the output of the comparator 42 becomes H'', so the transistor 43 turns QN and the relay coil 44 Then, the relay contact 39 is closed, the compressor 38 is operated, and the cooler 6 performs the cooling action.At the same time, the blower 6 is operated, and the cold air cooled by the cooler 6 is sent to the freezer compartment. 3° In addition to being forced to ventilate into the refrigerator compartment 4, it also flows through the discharge duct 17 through the air supply port 36 and into the first ventilation path 33.The cold air flowing through the first ventilation path 33 cools the cooling plate 13. Since the front end of the first ventilation path 33 is closed by bending the partition plate 32 into an oval shape, the cold air flowing forward in the first ventilation path 33 is blocked by the partition plate 32. It flows out downward through the communication hole 36, and the front of the second ventilation path 34,
That is, it flows into the front of the upper surface of the second ice tray 16. While the cold air flows from the front to the rear through the second ventilation path 34, the ice surface of the second ice tray 16 is cooled to produce normal ice. At this time, all of the cold air flowing through the first ventilation path 33 continues to flow through the second ventilation path 34 and is transferred to the second ice tray 1.
6, the cooling power is fully utilized and ice can be made in a short time. In addition, the second ventilation passage 3
The cool air that has flowed through the inside of the cooler 4 is discharged through the exhaust port 37 and returned to the cooler 6. After that, when the freezer compartment 3 is cooled to a predetermined temperature, the resistance value RT)(1 of the temperature sensor 31 increases, and the comparator 42 generates a Low signal (hereinafter referred to as "'L"). Therefore, the transistor 43 ○ FF, conduction to relay coil 44 is cut off, and relay contact 3
9 opens and the compressor 38° blower 6 stops. Thereafter, this action is repeated to perform the normal cooling action, and the cooling plate 13 of the first ice making compartment 22 is also kept sufficiently cooled. In this state, when the user tries to make transparent ice and puts the first ice tray 16 filled with water into the first ice making chamber 22 and turns on the ice making switch 3o at the same time, a 6H'' signal is output and the timer 47 is turned on. The subsequent operation will be explained using the characteristic diagram in FIG. 6.
When the signal is input, an "H" signal is output with a delay of a predetermined time t0, and one input of the AND circuit 49 becomes "H".

At this point, the water filled in the first ice tray 15 is on the cooling plate 1.
This is the process of being cooled down to 0°C by the cooling action of step 3, and when the first ice tray 16 is inserted, the atmospheric temperature inside the first ice making compartment 22 decreases due to the influence of the water temperature (30°C in this case). increases, and the temperature of the temperature sensor 28 also draws a rapid temperature increase curve through the ventilation holes of the heating plate 27 provided on the upper surface. However, this rising curve reaches its peak within a short period of time, and thereafter changes to a temperature decreasing curve as the water temperature falls. Delay time t of timer 47. is set so that the temperature characteristic of the temperature sensor 28 changes to a descending curve, and thereafter, as the water temperature falls, the temperature sensor 28 is also cooled and the resistance value RTH2 increases. When the temperature of the temperature sensor 28 reaches a predetermined temperature Tie corresponding to the water temperature reaching 0°C, the output of the comparator 46 becomes H'', and the other input of the AND circuit 49 also becomes H.
”, and the output of the AND circuit 49 becomes H for the first time at this point.
The ``H'' output of the AND circuit 490 is input to the reset terminal of the timer 47 to reset the contents of the timer 47 in preparation for the next turning on of the ice-making switch 3o.

On the other hand, a predetermined time t input into the timer 48
During this period, the "H" signal continues to be output. and transistor 6
0 is ONL during that time! The J-ray coil 61 becomes conductive, the relay contact 40 closes, and the heater 25 is energized. That is, the heating action from the heating plate 27 on the top surface of the first ice-making compartment 22 is started after the water temperature reaches approximately 0°C, and the o
Wasteful heating of the water until it reaches ℃ can be omitted, and the ice-making time can be shortened accordingly. Furthermore, since the temperature sensor 28 indirectly detects the water temperature and controls the heating start time, it is versatile even when the water temperature changes. Furthermore, since it is possible to avoid slow cooling while heating, the freezing action from water to ice occurs normally at the freezing point of 00°C, and a supercooling phenomenon occurs in which water is supercooled to below 04°C, resulting in an opaque state. There is no risk of ice formation.

And compressor 38. The heater 26 is energized in synchronization with the operation of the blower 6, and the heating effect from the upper heating plate 27 prevents the ice surface from freezing first.
Since the water is frozen in one direction from the bottom to the top by the cooling effect from the ice, when time t has elapsed, the gaseous components contained in the water are degassed from the ice surface, producing transparent ice that contains almost no air bubbles. . Incidentally, the time t is determined by giving a certain margin to the time required for the water to finish freezing. Then, when the time t has elapsed, the output of the timer 48 becomes "
"L", the transistor 50 is turned off, the conduction of the relay coil (V51) is cut off, the relay contact 40 is opened, and the power supply to the heater 26 is stopped.When the power supply to the heater 26 is stopped, the heating action from the heating plate 27 is stopped. The cooling effect from the cooling plate 13 on the lower surface rapidly cools the air.

Next, while the heater 25 is energized at the time t described above, that is, during the process of producing transparent ice, there is an external thermal influence on the inside of the first ice making compartment 22, such as a cooling influence from the freezing compartment 3 or a cooling influence from the freezing compartment 3. The ice making compartment 22 is hardly affected by the effects of heat intrusion from outside air due to the opening and closing of the door, as the bottom opening is closed by the openable and closable door body 29 provided at the front opening of the first ice making compartment 22. The formation of transparent ice can proceed under stable conditions. At the same time, the amount of heat leaking to the outside is smaller than that in the first ice-making compartment 22, and the heating efficiency of the heating plate 27 is increased.As a result, the capacity of the heater 25 can be reduced, and power consumption is also reduced.

On the other hand, the water vapor generated during the freezing process of the water in the second ice tray 16 is blocked by the partition plate 32 and remains at the exhaust port 37.
more excreted. Therefore, the cooling plate 13 is not affected by the heat of the water vapor, and the temperature of the cooling plate 13 does not rise. and,
The cooling power of the cooling plate 13 is not reduced and the time required to make transparent ice is not prolonged. In addition, the moisture in the steam is directly absorbed by the cooling plate 13.
Since no adhesion occurs on the bottom surface of the cooling plate 13, frost or ice does not develop on the bottom surface of the cooling plate 13. Therefore, the cold air flowing through the first ventilation path 33 can directly cool the cooling plate 13 without being hindered by frost or ice.
The cooling power of the cooling plate 13 is not reduced, and the time required to make transparent ice is not prolonged.

Effect of the invention As described above, according to the present invention, the following effects can be obtained.

(1) The time required for water to reach 0°C, the point at which it starts freezing, is shortened, and the time required to make transparent ice can be shortened. or,
It is versatile and can always demonstrate its effectiveness even under different water temperature conditions.

(2) Since it is possible to eliminate the slow cooling state by heating in the cooling section from water to ice, it is possible to prevent the occurrence of supercooling phenomenon and to prevent the mixing of opaque ice.

(3) Since the opening of the ice-making compartment is closed by the door, transparent ice can be produced under stable conditions without being affected by external heat. Furthermore, since the heating efficiency of the heating device, especially the heater, is increased, power consumption can be reduced.

(4) Since the cold air that has cooled the cooling plate of the first ice tray can be used directly to cool the second ice tray, ordinary ice can be made efficiently in a short time.

(6) Transparency caused by the first ice tray means that even if normal ice making is performed using the second ice tray during ice making, frosting and freezing may occur due to the thermal influence of water and generated water vapor during the normal ice making process. Since the influence of the ice tray does not affect the cooling plate of the first ice tray,
It does not take long to make clear ice using the ice cube tray.

[Brief explanation of the drawing]

Fig. 1 is a sectional view in the depth direction of an ice making device such as a refrigerator showing an embodiment of the present invention, Fig. 2 is a sectional view in the vertical direction, and Fig. 3 is a sectional view in the vertical direction.
The figure is a perspective view of the ice making device, Figure 4 is a sectional view of a refrigerator equipped with the same ice making device, Figure 6 is an electric circuit and control circuit diagram of the refrigerator, and Figure 6 is a diagram of how the ice making device makes transparent ice. Figure 7 is a cross-sectional view of a refrigerator equipped with a conventional ice-making device, Figure 8 is a front view of the ice-making device installed in the same refrigerator, and Figure 9 is a characteristic diagram when generating ice.
The figure is a cross-sectional view of the ice making device. 13... Cooling plate, 16... First ice tray,
16... Second ice tray, 21... Ice making device, 21a... Box body, 22... First
Ice making room, 23...Second ice making room, 24...
...Insulating material, 25...Heater (heating means),
26...Vent hole, 27...Heating plate, 2
8... Temperature sensor, 29... Group/door body, 32
...Group/partition plate, 33...First ventilation duct, 34
・Old...Second ventilation duct. Name of agent: Patent attorney Toshio Nakao and 1 other person l3
Figure 6 Figure 7 Section 8 Figure 9

Claims (1)

[Claims] A box body with an open front, a partition plate that partitions the inside of the box body into upper and lower parts, a cooling plate provided above the partition plate at a predetermined interval, and a first ice-making device formed in sections above the cooling plate. a second ice-making compartment partitioned at the bottom of the partition plate;
A first ice-making tray stored in the first ice-making chamber and placed on the cooling plate, and a heating means such as a heater, with a vent hole formed in a part of the top surface of the first ice-making tray. a heating plate provided, a temperature sensor for controlling the heating means provided on the back side of the heating plate opposite to the ventilation hole;
a heat insulating material disposed surrounding the ice-making compartment; a door body provided at the front opening of the first ice-making compartment that can be opened and closed; a second ice-making tray stored in the second ice-making compartment; a first ventilation path formed between the partition plate and the cooling plate and flowing from the rear to the front within the box; and a first ventilation path formed between the partition plate and the second ice tray in the second ice making chamber; An ice making device such as a refrigerator comprising a second ventilation passage communicating with the first ventilation passage and circulating from the front to the rear inside the box.