JP5757258B2 - Defroster for freezer cooling unit - Google Patents

Description

The present invention relates to a defrosting device for a freezer cooling unit installed in a freezer, located between plate fins in a cooler of the freezer cooling unit, and in contact with the surface of a heat transfer tube to change the temperature by heat conduction. A defrosting-finished thermostat fixture having an L-shaped horizontal cross section, comprising: a heat exchanging plate; and a thermostat installation plate that is integrally formed with the heat exchanging plate and that blocks the air flow perpendicular to the air flow direction. It is the technique which forms and attaches the said heat exchange plate of the said defrost completion | finish thermostat fixture to the said heat exchanger tube above the said cooler.

In the cooler in the cooling unit for the freezer, the low-temperature refrigerant flowing through the heat transfer tubes and the air flowing between the plate fins exchange heat, water vapor in the air condenses, and frost is generated in the plate fins. As the refrigeration operation takes longer, frost grows.
And by the growth of frost formation, heat exchange with a refrigerant | coolant and air worsens in the said cooler, and the operating efficiency of the freezing apparatus which has the said cooling unit for freezers worsens.

Therefore, conventionally, a defrosting heater is provided in the cooler, and the defrosting operation is performed by periodically energizing the defrosting heater.
Conventionally, with regard to the defrosting operation, in order to prevent frost from remaining unmelted and to prevent useless defrosting operation, it is important to accurately finish the defrosting, and various proposals have been made.

Conventionally, as an example of detecting the end of defrosting of the cooler, a refrigerant for detecting the end of defrosting is provided in the refrigerant pipe in the vicinity of the refrigerant outlet of the cooler so that it is likely to be the latest part of the end of defrosting. There is known a defrosting end device that uses a single sensor for detecting the end of defrosting by detecting the temperature of the refrigerant pipe in the vicinity of the outlet (see, for example, Patent Document 1).

JP-A-5-133644 (paragraph 0008, paragraph 0009, FIG. 1)

In the conventional technique described in Patent Document 1, the sensor that detects the end of defrosting detects the temperature of the refrigerant pipe in the vicinity of the refrigerant outlet that is away from the plate fin in the cooler. There was a problem that a delay occurred and a wasteful defrosting operation was performed.
That is, the conventional technique performs a wasteful defrosting operation because a delay occurs in the transfer of the heat of the defrosting heater to the refrigerant pipe provided with the sensor after the defrosting of the cooler is completed. How the frost grows on the cooler is greatly affected by the state of the freezer, especially when the cooler has little frost at the start of the defrosting operation, the defrosting of the cooler is completed in a short time. Nevertheless, there has been a problem that a delay occurs in the transfer of the heat of the defrost heater to the refrigerant pipe provided with the sensor, and it is easy to perform a useless defrost operation.

  An object of the present invention is to provide a defrosting device for a cooling unit for a freezer that can minimize wasteful defrosting operation in the conventional example described in Patent Document 1.

The defroster of the cooling unit for a freezer according to the present invention includes a large number of plate fins standing in parallel at predetermined intervals to form an air flow passage, and a refrigerant that cools air through the large number of plate fins. A cooler composed of a number of heat transfer tubes arranged in multiple rows in the direction of air circulation and in multiple stages in the vertical direction, a defrost heater for defrosting frost adhering to the plate fin, and temperature detection And a defrosting end thermostat that terminates defrosting when the set temperature is reached, a fan that blows during cooling and stops during defrosting, and a housing, the cooler on the air suction side in the housing, In a defrosting device for a freezer cooling unit installed in a freezer in which the fan is housed on the air blowing side in a housing, the refrigerant flows in a plurality of rows of the heat transfer tubes from the air blowing side to the air suction side. In Then, the refrigerant flow direction and the air flow direction in the cooler are opposed to each other, and the defrost heater is formed into a large number of straight pipes and divided into two groups of different numbers, so that a large number of the defrosts are formed. A heater is placed horizontally in contact with the end surface of the plate fin on the air suction side of the cooler, and a small group of the defrost heaters is placed on the lower end surface of the plate fin on the air outlet side of the cooler. Installed horizontally, positioned between the plate fins in the cooler, one end projecting into the housing from the end surface on the air blowing side of the plate fin and contacting the surface of the heat transfer tube A heat exchange plate that changes temperature due to heat conduction, and a thermostat installation plate that is integrally formed with the heat exchange plate and that blocks the air flow perpendicular to the air flow direction. The defrosting end thermostat fixture having an L-shaped horizontal cross section is formed, the heat exchange plate of the defrosting end thermostat fixture is attached to the heat transfer pipe above the cooler, and the temperature of the defrosting end thermostat The detection unit is brought into contact with the opposite surface of the thermostat installation plate of the defrosting end thermostat fixture on the cooler side, and the defrosting end thermostat is attached to the thermostat installation plate.

The defrosting device for a freezer cooling unit of the present invention is configured such that the refrigerant flows in a plurality of rows of the heat transfer tubes from the air blowing side to the air suction side, and the refrigerant flowing direction and the air flowing direction in the cooler. The defrost heater is formed into a number of straight tubes and divided into two groups of different numbers, and the groups of the defrost heaters are divided into the plate on the air suction side of the cooler. The defrosting heater of a small number group is placed in contact with the lower end face of the air blowing side in the cooler and placed horizontally in contact with the end face of the fin, and the cooler in the cooler Located between the plate fins, one end of the plate fin protrudes into the housing from the end surface on the air blowing side of the plate fin, and comes into contact with the surface of the heat transfer tube to change the temperature by heat conduction. A defrosting end thermostat fixture having an L-shaped horizontal cross section is provided, which includes a heat exchange plate and a thermostat installation plate that is integrally formed with the heat exchange plate and that blocks the air flow perpendicular to the air flow direction. The heat exchange plate of the defrosting end thermostat fixture is attached to the heat transfer pipe above the cooler, and the temperature detection part of the defrosting end thermostat is connected to the thermostat installation plate of the defrosting end thermostat fixture Since the defrosting end thermostat is attached to the thermostat installation plate in contact with the opposite surface of the cooler side, the defrosting end thermostat confirms that the frost on the plate fin of the cooler has disappeared without time delay. It can be detected and the defrosting operation can be terminated, preventing unnecessary defrosting operation and minimizing temperature rise in the freezer. It is possible to improve the operation efficiency of the refrigeration apparatus having the cooling unit.

It is a schematic block diagram which shows the cooling unit for freezers which concerns on Embodiment 1 of this invention. It is a perspective view which shows the cooler which attached the defrost completion | finish thermostat fixture which concerns on Embodiment 1 of this invention. It is a perspective view which shows the defrost completion | finish thermostat which concerns on Embodiment 1 of this invention, and its fixture. It is a figure which shows the defrost operation elapsed time and temperature which concern on Embodiment 1 of this invention, (a) is a case where frost formation of a cooler is small, (b) is a case where frost formation of a cooler is large. It is. It is the schematic which shows the cooler which attached the defrost heater which concerns on Embodiment 2 of this invention, (a) is a front schematic diagram, (b) is a side schematic diagram. It is a perspective view which shows the defrost completion | finish thermostat which concerns on Embodiment 3 of this invention, and its fixture. It is a figure which shows the defrost operation elapsed time and temperature which concern on the comparative example which shows a comparison with this invention shown in FIG. 4, (a) is a case where frosting of a cooler is small, (b) is a cooler's This is a case where frost formation is large. It is a figure which shows the modification of the plate fin of the cooling unit for freezers of this invention. It is a perspective view which shows a cooler when the defrost completion | finish thermostat of this invention is attached to a plate fin.

Embodiment 1 FIG.
1 to 4 are drawings according to Embodiment 1 of the present invention, FIG. 1 is a schematic configuration diagram showing a freezer cooling unit, and FIG. 2 is a perspective view showing a cooler to which a defrosting end thermostat fixture is attached. FIGS. 3 and 3 are perspective views showing a defrosting end thermostat and its attachment, and FIG. 4 is a view showing a defrosting operation elapsed time and temperature.
In FIG. 1, reference numeral 1 denotes a freezer cooling unit which is installed outside a freezer and connected to a refrigerator equipped with a compressor, a condenser, a condenser fan, etc., by a refrigerant pipe, electric wiring, etc. It is composed.

The freezer cooling unit 1 includes a housing 2, a cooler 3, a defrost heater 4, a defrost end thermostat 5, a defrost end thermostat fixture 6, a fan 7, and a fan motor 71. It is installed in a freezer and the interior is cooled to minus 30 ° C. or lower to store frozen foods and the like.
The cooler 3 is housed in the air suction side 21 in the housing 2, and the fan motor 71 and the fan 7 are housed in the air blowing side 22 in the housing 2.

As shown in FIG. 2, the cooler 3 includes a large number of plate fins 31 that are arranged in parallel at predetermined intervals to form an air flow passage, and a refrigerant that cools the air through the large number of plate fins 31. Is constituted by a hairpin type heat transfer tube 32 which circulates inside.
The heat transfer tubes 3 are arranged in a staggered manner in a plurality of rows (for example, 6 rows in FIG. 2) in the air flow direction and in multiple stages in the vertical direction.

Further, the refrigerant flows through the plurality of rows of the heat transfer tubes 32 from the air blowing side 22 to the air suction side 21 so that the refrigerant flowing direction and the air flowing direction in the cooler 3 are opposed to each other. .
In the cooler 3, the heat transfer tube 32 is a copper tube, the material of the plate fins 31 is aluminum, the plate thickness is 0.25 mm, and the fin pitch of the plate fins 31 is 6.35 mm.

The defrost heater 4 defrosts frost adhering to the plate fins 31 and is composed of a sheathed heater. As shown in FIG. 1, the defrost heater 4 is formed in a large number (for example, six in FIG. 1) in a straight tube shape. At the same time, it is divided into two groups of different numbers (for example, four and two in FIG. 1), and a large number of the defrost heaters 41 of the plate fins 31 on the air suction side 21 in the cooler 3 are separated. The defrosting heaters 42 of a small group are placed horizontally in contact with the end face, and are placed horizontally in contact with the lower end face of the plate fin 31 on the air blowing side 22 in the cooler 3. .
The defrosting end thermostat 5 is a bimetal switch type, and is turned off when the temperature detection unit reaches a set temperature or higher. The set temperature is set to 2 ° C. to 5 ° C., for example, 3.5 ° C. It is attached to the said defrost completion | finish thermostat fixture 6 shown in FIG.

The defrosting end thermostat fixture 6 is made of the same aluminum as the plate fins 31 and has a plate thickness of 2 mm, and is formed integrally with the heat exchange plate 61 and the heat exchange plate 61 as shown in FIG. In addition, a horizontal section provided with a thermostat installation plate 62 that is perpendicular to the air flow direction and blocks air flow is formed in an L shape.
The heat exchange plate 61 of the defrosting completed thermostat fixture 6 has six rows and four stages of through-holes through which the heat transfer tubes 32 pass so as to match the staggered arrangement of the heat transfer tubes 32 of the cooler 3. 63, and one end portion 64 of the heat exchange plate 61 is formed so as to protrude into the housing 2 from the end surface of the air blowing side 22 of the plate fin 31.

As shown in FIG. 2, the defrosting end thermostat fixture 6 brings the through holes 63 of the heat exchange plate 61 into contact with the heat transfer tubes 32 in six rows and four stages above the center of the cooler 3, The heat exchange plate 61 is attached to the heat transfer tube 32 so as to be positioned between the plate fins 31 in the cooler 3.
The defrosting end thermostat 5 is attached to the thermostat installation plate 62 by bringing the temperature detection unit into contact with the opposite surface 65 of the cooler 3 in the thermostat installation plate 62 of the defrosting end thermostat fixture 6. .

Further, as shown in FIG. 3, the defrosting end thermostat fixture 5 is provided with a plate-like member 66 that partially covers the defrosting end thermostat 6.
The plate-like member 66 includes a first member 67 positioned in the direction in which the heat exchange plate 61 is extended, and is parallel to the thermostat installation plate 62 perpendicular to the air flow direction from the end of the first member 67. The second member 68 is integrally formed.

The attachment of the defrosting end thermostat fixture 6 to which the defrosting end thermostat 5 is attached to the heat transfer tube 32 is simultaneously performed when the plate fin 31 is attached to the heat transfer tube 32.
Next, the operation will be described.

By operating a refrigerator outside the freezer constituting the refrigeration apparatus, the liquid refrigerant is evaporated in the heat transfer pipe 32 in the cooler 3 of the freezer cooling unit 1 installed in the freezer, and the plate fin 31 The air circulated by the fan 7 exchanges heat so that the circulating air is cooled and the inside of the freezer is kept at, for example, minus 30 ° C.
When the freezer cooling unit 1 is refrigerated for a long time, water vapor in the circulating air condenses on the surface of the plate fins 31 and becomes frost, and frost gradually grows.

When the plate fin 31 increases in frost formation, the heat conductivity of the frost is small, and the air flow path between the plate fins 31 is blocked and the circulation air volume by the fan 7 is reduced. The heat exchange with the air becomes worse, and the operating efficiency of the refrigeration system decreases.
Therefore, the monitor of the freezer in which the freezer cooling unit 1 is installed controls the control panel of the freezer so as to start the defrosting operation periodically, for example, every 48 hours according to the storage status of the frozen products in the freezer. The defrosting start timer provided in is set.

When the time set by the defrost start timer is counted, the defrost start timer is activated to stop the operation of the refrigerator, stop the fan 7 of the freezer cooling unit 1, and stop the cooling. The defrosting operation is started by stopping the cooling operation in the vessel 3 and energizing the defrost heater 4.
In the defrosting operation, heat is transferred from the defrosting heater 4 to the end face of the plate fin 31 to melt the frosting of the plate fin 31, and the large number of defrosting heaters 41 have a large heater capacity, Since the plate fin 31 on the air suction side 21 is heated, the frost can be melted even if the plate fin 31 on the air suction side 21 faces a low temperature (for example, minus 30 ° C.) portion in the freezer. I can do it.

In addition, although the minority group of defrosting heaters 42 has a small heater capacity, the fan motor 71 and the fan 7 are housed on the air blowing side 22 of the casing 2, and the air blowing is performed. Since the plate fins 31 on the side 22 are separated from the low temperature part in the freezer, the influence of the cold part in the freezer is small and frost formation can be melted.
And since the said heat exchange plate 61 of the said defrost completion | finish thermostat fixture 6 is not in contact with the said defrost heater 4, the heat of the said defrost heater 4 is not directly heat-transferred, but the said heat exchanger tube 32 The heat exchange plate 61 receives the heat due to the temperature of the heat transfer tube 32 and the radiant heat and convection heat due to the surface temperature of the plate fin 31 around the heat exchange plate 61 through the through hole 63 in contact with the heat exchange plate 61. The temperature of the thermostat installation plate 62 rises due to heat conduction from the heat exchange plate 61.

Since the temperature detection part of the defrosting end thermostat 5 is in contact with the opposite surface 65 of the thermostat installation plate 62 on the cooler 3 side, it detects the temperature of the opposite surface 65.
The opposite surface 65 of the thermostat installation plate 62 on the cooler 3 side is blocked by the thermostat installation plate 62 and the plate-like member 66 from circulating low-temperature circulating air during the freezing operation of the freezer cooling unit 1. In addition, since the air stays, frost is hardly formed, and it is difficult to be exposed to the low temperature in the freezer even during the defrosting operation.

Moreover, since the heat exchange plate 61 of the defrosting-completed thermostat fixture 6 retains air in the same manner as the thermostat installation plate 62, it hardly defrosts and defrosts the heat from the heat transfer tube 32. There is no need to spend on.
Here, the temperature T1 of the temperature detection part of the defrosting end thermostat 5 and the temperature T2 of the plate fin 31 at a position several sheets away from the defrosting end thermostat fixture 6 are plotted on the vertical axis, and the defrosting operation progresses. FIG. 4 shows the results of measurement with the time S as the horizontal axis.

In FIG. 4, the temperature T1 of the temperature detection unit and the temperature T2 of the plate fin 31 at the start of the defrosting operation (elapsed time 0) are substantially the same temperature, which is substantially the same as the temperature in the freezer. Yes.
With the progress of the defrosting operation, both the temperature T1 of the temperature detection unit and the temperature T2 of the plate fin 31 increase, but the heat of the defrosting heater 4 is thicker in the defrosting end thermostat fixture 6. Therefore, it is easy to be transmitted by heat conduction, and the temperature T1 of the temperature detection unit rises faster than the temperature T2 of the plate fin 31.

When the temperature T2 of the plate fin 31 reaches 0 ° C., the heat from the defrost heater 4 becomes the heat of frost melting, maintains 0 ° C., and the frosting of the cooler 3 is a small amount of (a). In this case, the elapsed time for maintaining 0 ° C. is short, and in the case (b) where the frosting of the cooler 3 is large, the elapsed time for maintaining 0 ° C. becomes long.
While the temperature T2 of the plate fin 31 is maintained at 0 ° C., the temperature T1 of the temperature detection unit is such that the heat of the defrost heater 4 is consumed for melting frost and the temperature of the heat transfer tube 32 is Since it is difficult to rise, the temperature rise becomes gradual as shown in (a) and (b).

When the defrosting of the cooler 3 is finished, the temperature T2 of the plate fin 31 rises to the same temperature as the temperature T1 of the temperature detection unit, and even if the defrosting operation is continued, the temperature T1 of the temperature detection unit And the temperature T2 of the plate fin 31 rises at the same temperature.
Therefore, the defrosting operation is performed by setting the set temperature TS at which the defrosting of the defrosting end thermostat 5 is terminated to, for example, 3.5 ° C. at which the temperature T1 of the temperature detecting unit and the temperature T2 of the plate fin 31 are the same. In the elapsed time SE, the defrosting operation is terminated and the useless defrosting operation is prevented.

Further, when the defrosting heater 4 is brought into contact with the defrosting-finished thermostat fixture 6, as shown in the comparative example of FIG. 7, when the frosting of the cooler 3 is a small amount (a), the cooling In the case where the amount of frost on the cooler 3 is large (b), in the defrosting operation elapsed time SE that is the end of the defrosting of the cooler 3, the temperature T1 of the temperature detector and the temperature T2 of the plate fin 31 The temperature difference between the defroster thermostat 5 and the defrosting end thermostat 5 must be set at the temperature at which the defrosting of the cooler 3 is finished, and the defrosting thermostat 5 must be finished at any temperature. It has been found that it is important to prevent the defrosting heater 4 from coming into contact with the defrosting end thermostat fixture 6 because it is unavoidable to perform the operation.
In the first embodiment described above, the defrosting end thermostat fixture 6 is configured to attach the heat exchange plate 61 to the heat transfer tube 32 above the center of the cooler 3, but above the cooler 3. If so, it does not have to be in the center.

Embodiment 2. FIG.
Next, FIG. 5 is a drawing according to Embodiment 2 of the present invention, and is a schematic diagram showing a cooler to which a defrost heater is attached, (a) is a front view of the air blowing side of the cooler, b) is a side view.
The second embodiment is a modification of the defrosting heater in the first embodiment. As shown in FIG. 5, a small number (two) of the defrosting heaters 42 shown in FIG. Instead of being placed horizontally in contact with the lower end surface of the plate fin 31 on the air blowing side 22, a U-shaped defrosting heater 43 is connected to the plate fin 31 on the air blowing side 22 in the cooler 3. It was installed in contact with both sides in the width direction and the lower part.

That is, the defrost heater 4 is divided into a large number of straight tubular majority groups and a U-shape, and the multiple groups of the defrost heaters 41 are arranged on the plate on the air suction side 21 in the cooler 3. The U-shaped defrosting heaters 43 are arranged in contact with the end surfaces of the fins 31 and are horizontally distributed. It was installed in contact with the part.
Note that the heat exchange plate 61 of the defrosting completed thermostat fixture 6 is attached to the heat transfer tube 32 at the upper center in the width direction of the cooler 3 as in the first embodiment. Then, it is not necessary to attach the heat exchange plate 61 to the heat transfer tube 32 in the center in the width direction of the cooler 3, but in this embodiment, since the U-shaped defrost heater 43 is provided, It is necessary for the temperature detection part of the defrosting end thermostat 5 to prevent the thermal effects indicated by the arrows from the left and right sides of the U-shaped defrosting heater 43 from being biased, and the heat exchange plate 61 is connected to the cooler. 3 is attached to the heat transfer tube 32 above the center in the width direction.

The U-shaped defrosting heater 43 forms one sheathed heater in a U-shape, but the unit length is such that the amount of heat generated per unit length is the same as that of the defrosting heaters 41 in a large number of groups. The resistance value per unit is changed.
Further, the U-shaped defrosting heater 43 may have three straight tubes.

Except for the above description, the second embodiment has the same configuration and operation as the first embodiment, and thus the description thereof is omitted.

Embodiment 3 FIG.
Next, FIG. 6 is a drawing according to Embodiment 3 of the present invention, and is a perspective view showing a defrosting end thermostat and its fixture.
This Embodiment 3 is a modification of the defrosting end thermostat fixture in Embodiment 1, and as shown in FIG. 6, six rows through which the heat transfer tubes 32 penetrate the heat exchange plate 61 shown in FIG. 3. Instead of the four-stage through holes 63, three semicircular cutouts 69 that engage with the three uppermost heat transfer tubes 32 of the cooler 3 are formed at the lower end of the heat exchange plate 61a. Yes.

And this Embodiment 3 attaches the said defrost end thermostat fixture 6a which attached the said defrost end thermostat 5 to the said heat exchanger tube 32, when attaching the said plate fin 31 to the said heat exchanger tube 32, Although it is performed simultaneously, the installation position of the defrosting end thermostat fixture 6a in the left and right direction in the cooler 3 can be adjusted at the site where the freezer cooling unit 1 is installed in the freezer and the trial operation is performed.
However, the third embodiment has an advantage that the mounting position of the defrosting-end thermostat fixture 6a can be adjusted, but the semicircular cutout 69 of the heat exchange plate 61a, the heat transfer tube 32, and the like. Therefore, there is a demerit that the amount of heat conduction from the heat transfer tube 32 to the heat exchange plate 61a is smaller than that of the first embodiment.

Modification of Embodiments 1 to 3 In the above Embodiments 1 to 3, the start of the defrosting operation is performed by the defrosting start timer, but the start of various known defrosting operations Of course, means can be adopted.
Moreover, in the above Embodiment 1- Embodiment 3, although the plate-shaped member 66 which partially covers the said defrost end thermostat 5 was provided in the said defrost end thermostat fixtures 6 and 6a, this plate shape The member 66 may be omitted.

In the first to third embodiments described above, the defrosting end thermostat 5 is installed on the defrosting end thermostat fixtures 6 and 6 a, but the plate fin 31 protrudes into the housing 2. The defrosting end thermostat 5 may be installed on the projection of the plate fin 31.
The plate fin 31 in which the protrusion is formed in place of the defrosting end thermostat fixtures 6 and 6a by allowing the defrosting end thermostat 5 to be installed on the protrusion of the plate fin 31. Can be used, and the installation position of the defrosting end thermostat 5 can be moved according to the use environment.

  In Embodiment 1 to Embodiment 3 above, the set temperature at which the defrosting of the defrosting end thermostat 5 is finished is 3.5 ° C., but it may be 2 ° C. to 5 ° C., and frost remains unmelted. If this happens, it will be even higher.

DESCRIPTION OF SYMBOLS 1 Cooling unit 2 for freezer Case 3 Cooler 4 Defrost heater 5 Defrost end thermostat 6, 6a Defrost end thermostat fixture 7 Fan 21 Air suction side 22 Air blowing side 31 Plate fin 32 Heat transfer tube 41 Removal of many groups Frost heater 42 Minority group defrost heater 43 U-shaped defrost heater 61, 61 a Heat exchange plate 62 Thermostat installation plate 63 Through hole 64 One end portion 65 Opposite surface 66 Plate-like member

Claims (5)

A large number of plate fins standing in parallel at predetermined intervals to form an air flow passage, and a plurality of rows in the air flow direction in which the refrigerant that passes through the large number of plate fins and cools the air flows in the vertical direction A cooler composed of a large number of heat transfer tubes arranged in multiple stages,
A defrost heater for defrosting frost adhering to the plate fin;
A defrosting end thermostat that detects the temperature and terminates the defrosting when the set temperature is reached;
A fan that blows during cooling and stops during defrosting;
A defroster for a cooling unit for a freezer installed in a freezer that houses the cooler on the air suction side in the housing and the fan on the air blowing side in the housing,
Refrigerant flows through the heat transfer tubes in a plurality of rows from the air blowing side to the air suction side, and the refrigerant flow direction and the air flow direction in the cooler are set as counterflows,
The defrost heater is formed into a number of straight pipes and divided into two groups of different numbers, and the groups of the defrost heaters are brought into contact with the end surfaces of the plate fins on the air suction side of the cooler. And horizontally installed, a small group of the defrost heater is placed in contact with the lower end surface of the plate fin on the air blowing side in the cooler, and installed horizontally,
Located between the plate fins in the cooler, one end portion projects into the housing from the end surface of the plate fin on the air blowing side and contacts the surface of the heat transfer tube to change the temperature by heat conduction. A defrosting end thermostat fixture having an L-shaped horizontal cross section is provided, which includes a heat exchange plate and a thermostat installation plate that is integrally formed with the heat exchange plate and that blocks the air flow perpendicular to the air flow direction. And
Attach the heat exchange plate of the defrosting completed thermostat fixture to the heat transfer tube above the cooler,
The defrosting end thermostat is attached to the thermostat installation plate by bringing the temperature detection part of the defrosting end thermostat into contact with the opposite surface on the cooler side of the thermostat installation plate of the defrosting end thermostat fixture. A defroster for a freezer cooling unit. A large number of plate fins standing in parallel at predetermined intervals to form an air flow passage, and a plurality of rows in the air flow direction in which the refrigerant that passes through the large number of plate fins and cools the air flows in the vertical direction A cooler composed of a large number of heat transfer tubes arranged in multiple stages,
A defrost heater for defrosting frost adhering to the plate fin;
A defrosting end thermostat that detects the temperature and terminates the defrosting when the set temperature is reached;
A fan that blows during cooling and stops during defrosting;
A defroster for a cooling unit for a freezer installed in a freezer that houses the cooler on the air suction side in the housing and the fan on the air blowing side in the housing,
Refrigerant flows through the heat transfer tubes in a plurality of rows from the air blowing side to the air suction side, and the refrigerant flow direction and the air flow direction in the cooler are set as counterflows,
The defrost heater is divided into a large number of straight tubular majority groups and a U-shape, and the multiple groups of defrost heaters are brought into contact with the end surfaces of the plate fins on the air suction side of the cooler. Installed horizontally distributed, installed the U-shaped defrost heater in contact with the width direction both sides and the lower part at the end face of the air blowing side of the plate fin in the cooler,
Located between the plate fins in the cooler, one end portion protrudes into the housing from the end surface of the plate fin on the air blowing side and contacts the surface of the heat transfer tube to change the temperature by heat conduction. A defrosting end thermostat fixture having an L-shaped horizontal cross section is provided, which includes a heat exchange plate and a thermostat installation plate that is integrally formed with the heat exchange plate and that blocks the air flow perpendicular to the air flow direction. And
Attach the heat exchange plate of the defrosting completed thermostat fixture to the heat transfer tube at the upper center in the width direction of the cooler,
The defrosting end thermostat is attached to the thermostat installation plate by bringing the temperature detection part of the defrosting end thermostat into contact with the opposite surface on the cooler side of the thermostat installation plate of the defrosting end thermostat fixture. A defroster for a freezer cooling unit.   The heat exchange plate of the defrosting-finished thermostat fixture is provided with through-holes that penetrate all the upper rows of the heat transfer tubes of the cooler in the row number direction, and pass through the heat exchange plate. The defrosting device for a cooling unit for a freezer according to claim 1 or 2, wherein a hole is brought into contact with the heat transfer tube, and the heat exchange plate is attached to the heat transfer tube.   The defrosting of the cooling unit for a freezer according to any one of claims 1 to 3, wherein a plate-like member that partially covers the defrosting end thermostat is provided on the defrosting end thermostat fixture. apparatus.   The defrosting device for a cooling unit for a freezer according to any one of claims 1 to 4, wherein a set temperature at which the defrosting of the defrosting end thermostat is terminated is 2 ° C to 5 ° C.

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