JP6744731B2 - refrigerator - Google Patents

Description

The present invention relates to a refrigerator, and relates to a defrosting operation for removing frost attached to an evaporator.

A conventional refrigerator is disclosed in Patent Document 1. This refrigerator is provided with a glass tube heater (indirect heating means) arranged below the evaporator and a sheath heater (direct heating means) arranged in contact with the evaporator for defrosting the evaporator. ing. Then, a sensor (detection means) for detecting the temperature at the top, bottom, left, right, center, etc. of the evaporator is attached, and on/off and output control of the glass tube heater and the sheath heater is performed based on the detection signal from the sensor. Is going.

Since the glass tube heater and the sheath heater are controlled on the basis of detection signals from temperature sensors arranged at a plurality of locations in the evaporator, it is possible to make the temperature of the evaporator uniform.

Japanese Patent Laid-Open No. 2000-121233

However, in the case of the refrigerator described in Patent Document 1, a plurality of sensors and a plurality of heating means are used, and the temperature in the vicinity of the portion detected by the sensors is raised to uniformly heat the evaporator. Therefore, many sensors are required, the configuration is complicated, and the cost is increased. Further, since the configuration is such that the outputs of the plurality of heating means are adjusted or ON/OFF is controlled based on the detection signals from the plurality of sensors, the control is complicated and required by the control circuit. Ability to improve. This causes an increase in the cost of the refrigerator.

Therefore, it is an object of the present invention to provide a refrigerator having a simple configuration, capable of efficiently performing a defrosting operation for removing frost formation on an evaporator and reducing power consumption.

In order to achieve the above object, the present invention is a refrigerator that cools a storage chamber with air cooled by an evaporator, comprising: a first temperature measuring unit that measures a temperature of an upper portion of the evaporator; A second temperature measuring part for measuring the temperature of the lower part, a first heating device arranged below the evaporator for indirectly heating the evaporator, and at least an upper part of the evaporator for direct heating. A second heating device, and a control that acquires the first temperature measured by the first temperature measurement unit and the second temperature measured by the second temperature measurement unit and controls the operations of the first heating device and the second heating device. The control unit starts the operation of the second heating device when the second temperature is higher than the second threshold value, and the operation of the second heating device when the first temperature is higher than the first threshold value. The control is performed in the first heating mode that ends the.

According to this structure, the lower part of the evaporator having a large amount of frost is heated by the first heating device, and the upper part having a small amount of frost is heated by the second heating device. Then, after the heating by the first heating device is started, the heating of the second heating device is performed with a delay, so that in the first heating device in the upper part of the evaporator, the portion that is difficult to heat is also heated. As a result, uneven heating of the evaporator can be suppressed, and reliable defrosting is possible. Further, the evaporator can be uniformly heated in a short time as compared with the case of heating only by the first heating device, and energy saving can be achieved. Further, only by controlling the operation of the second heating device based on the temperature of the upper part and the temperature of the lower part of the evaporator, it is possible to uniformly heat the evaporator with simple control.

In the above configuration, the control unit may perform control to stop the first heating device when the second temperature reaches a third threshold value higher than the second threshold value. By doing so, even if the evaporator is in a frosted state which is different from usual or unexpected, it is possible to suppress excessive heating of the lower portion. As a result, useless power consumption can be suppressed and energy can be saved.

In the above configuration, in the first heating mode, the control unit may start the operation of the second heating device later than the start of the operation of the first heating device.

In the above-described configuration, the control unit may perform the operation stop of the first heating device after the operation stop of the second heating device in the first heating mode.

In the above configuration, the control unit can control in a second heating mode in which the first heating device is operated and the second heating device is stopped, and the control unit calculates the frost formation amount of the evaporator by calculation. It has acquired, and the said control part may switch the said 1st heating mode and the said 2nd heating mode based on the said amount of frost formation. With such a configuration, it is possible to perform an efficient defrosting operation regardless of the frosted state of the evaporator. Thereby, a stable energy saving effect can be obtained over a long period of time.

According to the present invention, it is possible to provide a refrigerator having a simple configuration, capable of efficiently performing defrosting operation for removing frost formation on an evaporator, and reducing power consumption.

It is a schematic front view of an example of the refrigerator concerning this invention. It is a cross-sectional view of the refrigerator shown in FIG. It is a block diagram of the refrigerator shown in FIG. It is a figure which shows schematic structure of an evaporator. It is a flow chart showing the defrosting operation of the refrigerator concerning the present invention. It is a timing chart which shows operation of a glass tube heater and a sheath heater. It is a flowchart at the time of performing a defrosting operation. 7 is a timing chart of a modified example of the timing chart shown in FIG. 6. It is a graph which shows the relationship between the measured value of a 1st temperature sensor, the measured value of a 2nd temperature sensor, and the amount of frost formation of an evaporator. It is a flow chart of the defrosting operation of the refrigerator concerning the present invention.

Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic front view of an example of a refrigerator according to the present invention. FIG. 2 is a cross-sectional view of the refrigerator shown in FIG. FIG. 3 is a block diagram of the refrigerator shown in FIG. In the following description, the front-back direction, the up-down direction, the left-right direction, and the like may be shown, but in this case, the state shown in FIG. 1 is used as a reference. Further, when describing the front side (front side) and the back side (rear side), the state shown in FIG. 2 is used as a reference, and in FIG. 2, the left side is the front side (front side) and the right side is the back side (rear side). As described below. The arrows in FIGS. 1 and 2 indicate the flow of cool air.

As shown in FIGS. 1 and 2, the refrigerator Rf has a heat insulating box 100 which is open on the front side and is surrounded by a wall body filled with a foam heat insulating material. The heat insulating box 100 is provided with a partition shelf 101 that partitions the inside into upper and lower parts. Further, a machine room 102 is provided on the rear side of the lower part of the heat insulating box 100. The machine room 102 is separated from the space of the heat-insulating box 100 for storing the articles and the wall body filled with the foam heat insulating material. A part of a cooling device for cooling each storage room of the refrigerator Rf is arranged in the machine room 102. In the refrigerator Rf, a compressor Comp and a control unit Cont (see FIG. 3) are arranged. In addition, devices other than these may be arranged.

The partition shelf 101 is filled with a foamed heat insulating material, like the other wall bodies, and divides the space of the heat insulating box 100 for storing the articles into upper and lower parts. In addition, here, the lower side of the partition shelf 101 is the first space 1 and the upper side is the second space 2. In the refrigerator Rf, the first space 1 is provided with a storage room that is maintained at a temperature (for example, −18° C. or lower) that can surely freeze the article. The second space 2 is provided with a storage chamber that is maintained at a temperature lower than that of the outside and at a temperature at which the article is hard to freeze (for example, about 0° C. to about 8° C.).

As shown in FIGS. 1 and 2, the first space 1 is provided with a lower freezing compartment 11, an upper freezing compartment 12, and an ice making compartment 13. The lower stage freezing chamber 11 and the upper stage freezing chamber 12 are storage chambers for storing stored materials in a frozen state (for example, storing at −18° C. or lower). The ice making chamber 13 is a storage chamber for producing and storing ice. In the refrigerator Rf, the lower freezing compartment 11, the upper freezing compartment 12 and the ice making compartment 13 are one heat insulating area.

As shown in FIG. 1, the lower freezer compartment 11 is provided in the lower portion of the first space 1. The lower freezing compartment 11 includes a first storage case 111, a second storage case 112, a third storage case 113, and a door 114. The door 114 is a drawer door that opens and closes by moving back and forth. The first storage case 111 is a storage case having the largest capacity in the lower freezing compartment 11, and is arranged at the bottom of the lower freezing compartment 11. The first storage case 111 moves integrally with the door 114. The second storage case 112 is arranged above the first storage case 111, and the third storage case 113 is arranged above the second storage case 112.

When the door 114 is opened, the second storage case 112 and the third storage case 113 are movable in the front-rear direction independently of the first storage case 111. In the lower freezer compartment 11, when the door 114 is opened and closed, the second storage case 112 and the third storage case 113 move together with the first storage case 111.

The upper part of the lower freezing chamber 11 of the first space 1 is divided into left and right parts, the divided right side is the upper freezing chamber 12, and the left side is the ice making chamber 13. The upper freezer compartment 12 includes a door 121 and a storage case 122. The door 122 is a drawer door that opens and closes by moving back and forth. The storage case 122 moves integrally with the door 121.

The ice making chamber 13 includes a door 131, a storage case 132, and an ice making machine 133. The door 131 is a drawer door that opens and closes by moving back and forth. The storage case 132 moves integrally with the door 131. The ice maker 133 is a device that freezes water supplied from a water tank (not shown) to produce ice. The ice making machine 133 is arranged above the storage case 132, and the produced ice falls into the storage case 132.

As shown in FIG. 2, a partition wall 14 is provided on the inner side of the first space 1. Between the partition wall 14 and the wall surface on the back side of the first space 1, a cold air flow path 3 through which cold air for cooling the lower freezing chamber 11, the upper freezing chamber 12 and the like flows is provided. As shown in FIG. 1, the first space 1 of the heat insulating box 100 is provided with a groove extending vertically in the central portion, and the partition wall 14 covers the front surface of the groove. The gap between the partition wall 14 and the groove is the cold air passage 3.

The cold air passage 3 is divided into front and rear by a partition member 30. The rear side of the partition member 30 is the cool air generating portion 31, and the front side is the cool air duct 32. The cool air generator 31 is provided with an evaporator 5 which is a cooler of the refrigerator Rf and a freezing fan 33. The evaporator 5 cools the surrounding air by removing heat from the surrounding air when the refrigerant evaporates inside. Details of the evaporator 5 will be described later. The freezing fan 33 is a blower that generates a flow of air (airflow) in the cold air passage 3. The freezing fan 33 is arranged above the evaporator 5. By operating the refrigerating fan 33, an ascending airflow is generated in the cold air generating unit 31. That is, by operating the freezing fan 33, the air flow passes through the evaporator 5. In the refrigerator Rf, the freezing fan 33 operates while the cooling device is performing the cooling operation.

The cool air generating part 31 is connected to the cool air duct 32 at the upper part. The cold air generated by the cold air generating unit 31 flows into the cold air duct 32. The cold air duct 32 is an air passage for supplying cold air to the lower freezing compartment 11 and the upper freezing compartment 12. The cold air duct 32 is provided with discharge ports 321, 322, 323 and 324 which are through holes formed in the partition wall 14. The discharge ports 321, 322, 323 are provided at positions where cold air flows into the first storage case 111, the second storage case 112, and the third storage case 113 of the lower freezer compartment 21, respectively. Further, the discharge port 324 is provided at a position where the discharge port 324 flows into the upper freezing chamber 12. In the refrigerator Rf, the cold air is made to flow into the ice making chamber 13 from the upper freezing chamber 12, but a discharge port for making the cold air flow into the ice making chamber 13 may be provided.

The cold air that has flowed into the lower freezing chamber 11 and the upper freezing chamber 12 and has cooled the inside of the first space 1 returns to the cold air generating unit 31 via the freezing return duct 34. The freezing return duct 34 is provided below the first storage case 111, and is connected to the cool air generating unit 31 below the evaporator 5. That is, the cold air that has cooled the lower freezing chamber 11, the upper freezing chamber 12, and the ice making chamber 13 passes through the return duct 34 and returns to the cold air generating unit 31. The cool air returning to the return duct 34 may be referred to as freezing return cold air.

As shown in FIGS. 1 and 2, the second space 2 is provided with a refrigerating chamber 21, a chilled chamber 22, and a vegetable chamber 23 from the top. The refrigerating chamber 21 is maintained at a low temperature (for example, 3°C to 5°C) that can suppress deterioration of the article. Further, the chilled chamber 22 is lower than the refrigerating chamber 21 and is maintained at a temperature (for example, 0° C. to 1° C.) at which the article is unlikely to freeze. The vegetable compartment 23 is maintained at a temperature (for example, 7° C. to 8° C.) that suppresses deterioration of freshness of vegetables. It should be noted that these storage chambers and their maintenance temperatures are examples, and may be in a temperature range in which the article does not freeze easily, or may be provided with a storage chamber having a temperature different from these.

The front side of the second space 2 is open, and a refrigeration door 27 is provided on the front side so as to be openable and closable. The refrigerating door 27 is pivotally supported by the heat insulating box 100 and rotates about a support shaft to open and close the opening of the second space 2. The refrigerating door 27 may be one that can close the opening of the second space 2 with one member (door), or one that can be closed with two or more members (door). Good. Here, the refrigerating door 27 is capable of closing the opening of the second space 2 with one sheet.

In the refrigerator Rf, by opening the refrigerating door 27, articles can be stored in the refrigerating compartment 21, the chilled compartment 22, and the vegetable compartment 23, or the stored articles can be taken out. Inside the refrigerating door 27, there is provided a door pocket 271 for storing articles such as bottles, cans, and paper packs that are to be stored in an upright position.

The refrigerating room 21 is provided with a movable shelf 24 that can divide the space into upper and lower parts. As shown in FIGS. 1 and 2, three movable shelves 24 are provided. The movable shelf 24 is used as a shelf by engaging with a convex portion (not shown) protruding from the inner wall of the refrigerating chamber 21. The movable shelf 24 can change its position in the refrigerating chamber 21 in the height direction. By changing the position of the movable shelf 24, a wide variety of articles having different shapes (for example, size, height) can be stored. A fixed shelf 25 fixed to the inner wall of the heat insulating box 100 is attached to the lowest stage of the refrigerating chamber 21.

Further, a fixed shelf 26 fixed to the inner wall of the heat insulating box 100 is attached below the fixed shelf 25 with a constant space. The portion sandwiched between the fixed shelves 25 and the fixed shelves 26 is the tilt chamber 22, and the portion sandwiched between the fixed shelves 26 and the partition shelf 101 is the vegetable compartment 23. The chilled chamber 22 includes a storage case 221. The storage case 221 is provided so as to be slidable back and forth. A front door 222 that opens and closes the front surface of the chilled chamber 22 is provided on the front surface of the storage case 221. A packing is provided on at least one of the inner surface of the front door 222 or the chilled chamber 22. When the storage case 221 is stored in the back, the front door part 222 closes the opening on the front surface of the chilled chamber 22. Further, the chilled chamber 22 has a restricted air flow, and has a temperature different from that of the refrigerating chamber 21.

The vegetable compartment 23 also has the same configuration as the chilled compartment 22, and includes a storage case 231 and a front door 232. Unlike the chilled chamber 22, the vegetable chamber 23 has a gap that allows air to flow in. Thereby, the cold air which has cooled the refrigerating chamber 21 and the chilled chamber 22 described later can be flowed into the vegetable chamber 23. A return opening 441 of a refrigeration return duct 44, which will be described later, is provided on the back side of the vegetable compartment 23. The cool air flowing from the return opening 441 flows into the refrigeration return duct 44.

As shown in FIG. 2, a partition 28 is provided at the back of the second space 2. Between the partition wall 28 and the wall surface on the inner side of the second space 2, the cold air flow path 4 through which cold air for cooling the refrigerating compartment 21, the chilled compartment 22 and the vegetable compartment 23 flows is provided. As shown in FIG. 1, the second space 2 of the heat insulating box 100 is provided with a groove extending vertically in the central portion, and the partition wall 28 covers the front surface of the groove. Then, the gap between the partition wall 28 and the groove becomes the cold air flow path 4.

The cold air flow path 4 includes a damper 41, a refrigeration fan 42, a discharge port 43, and a refrigeration return duct 44. The damper 41 opens and closes the through hole 103 provided in the partition shelf 101 as needed to adjust the inflow of cold air from the cold air passage 3. The refrigerating fan 42 is a blower for pushing away the cool air that has flown in by opening the damper 41. The operation of the refrigerating fan 42 causes the cool air to rise in the cool air passage 4. The discharge port 43 is a through hole provided in the partition wall 28. The refrigerator Rf is provided with five discharge ports 43, but the number is not limited to this, and may be more or less. It may be provided at least at a position where cold air flows into the refrigerating chamber 21 and the chilled chamber 22.

The cold air flowing through the cold air flow path 4 flows into the refrigerating chamber 21 and the chilled chamber 22 via the discharge port 43. The vegetable compartment 23 has a higher storage temperature than the refrigerating compartment 21 and the chilled compartment 22. Therefore, the vegetable compartment 23 is cooled by inflowing the cold air that has been heated in the refrigerator compartment 21 and the chilled compartment 22 by taking heat from the articles. The cold air that has cooled the vegetable compartment 23 passes through the refrigeration return duct 44 and is returned to the cold air generating unit 31 provided with the evaporator 5. The cold air that has cooled the vegetable compartment 23 and flowed into the refrigeration return duct 44 may be referred to as refrigeration return cold air.

The refrigeration return duct 44 extends downward from the back side of the vegetable compartment 23 to the back side of the first space 1. The refrigeration return duct 44 includes a return opening 441 and a return opening 442. The refrigeration return duct 44 is formed in the space sandwiched between the groove and the partition wall 28, like the cold air passage 4. The return opening 441 is a through hole that penetrates the partition wall 28. The refrigerated cold air that has flowed in from the return opening 441 flows downward in the refrigerated return duct 44. Then, as shown in FIG. 1, from the lower right side of the evaporator 5, it returns to the cool air generating portion 31 of the cool air passage 3.

The cooling device of the refrigerator Rf according to the present invention is configured to cool all the storage chambers with one evaporator 5. The cold air passage 3 and the cold air passage 4 are communicated with each other through the through hole 103 of the partition shelf 101, and the opening and closing of the damper 41 adjusts the inflow amount of the cold air generated in the cold air passage 3 into the cold air passage 4. Has been done. That is, when the cooling device is operating with the damper 41 closed, the cool air generated in the cool air generating unit 31 circulates in the first space 1. Further, when the damper 41 is opened and the cooling device is operating, the cold air circulates in both the first space 1 and the second space 2. That is, the damper 41 is opened only when the refrigerating compartment 21, the chilled compartment 22 and the vegetable compartment 23 are cooled.

The cooling device of the refrigerator Rf will be described. The cooling device uses a refrigeration cycle. The refrigeration system has a configuration in which a compressor Comp, a condenser (not shown), an expander (not shown), and an evaporator 5 are connected by pipes (not shown), and the inside thereof is filled with a refrigerant. There is. In a refrigeration system, a compressor compresses a refrigerant and a condenser condenses it. The condensed refrigerant is expanded by the expander and then evaporated by the evaporator 5. Then, the heat of vaporization due to the evaporation of the refrigerant is removed from the air to generate cold air. Since the cooling device uses a well-known technique, its details are omitted.

Next, the evaporator 5 will be described with reference to the drawings. FIG. 4 is a diagram showing a schematic configuration of the evaporator. As shown in FIG. 4, the evaporator 5 includes a pipe 51 and fins 52. As shown in FIG. 4, the pipe 51 has an inflow part and an outflow part into which the refrigerant flows. The pipe 51 meanders to the left and right toward the bottom, folds back at the lower end in a direction intersecting the meandering direction (the depth direction of the paper in FIG. 4), and again meanders to the top and left and right.

The fin 52 is a flat plate. A plurality of fins 52 are provided and arranged in parallel in the lateral direction. The pipe 51 penetrates the fin 52, and the pipe 51 and the fin 52 are connected. The pipes 51 and the fins 52 are made of a material having a high thermal conductivity (for example, a metal material such as aluminum or copper). The air flowing between the fins 52 is heat-exchanged with the refrigerant flowing inside the pipe 51 to become cool air.

As described above, the cool air generated in the evaporator 5 returns to the cool air generating unit 31 provided with the evaporator 5 after cooling each storage chamber of the refrigerator Rf. When the returned cold air is referred to as return cold air, the return cold air cools the inside by receiving heat from the articles and the air in each storage chamber of the refrigerator Rf. Therefore, the temperature of the returned cool air is higher than that when it is generated in the cool air generation unit 31. Then, the returned cold air is cooled again when passing through the evaporator 5, and is sent to each storage chamber as cold air.

For example, if the door is fully opened for a long time, or if an article having a high temperature or water that easily evaporates water is stored, the humidity of the returning cold air increases. Then, when the cool air having high humidity is cooled by the evaporator 5, the moisture contained in the return cool air adheres as frost on the surface of the evaporator 5. Due to the adhesion of frost, the fins 52 are blocked, and it becomes difficult for air to flow between the fins 52, and the cooling efficiency is reduced. Therefore, in the refrigerator Rf, the defrosting operation of heating the evaporator 5 to melt the frost is performed.

Next, the configuration required for the defrosting operation will be described. In order to perform the defrosting operation, a first temperature sensor 61 that measures the temperature of the evaporator 5, a second temperature sensor 62, a glass tube heater 7 that indirectly heats the evaporator 5 during the defrosting operation, and an evaporator. A sheath heater 8 for directly heating the container 5 is provided. The first temperature sensor 61 is provided above the evaporator 5. The second temperature sensor 62 is provided below the evaporator 5. In addition, the cool air is returned to the evaporator 5 from below.

If the cool air is blown directly to the second temperature sensor 62, it is difficult to detect the accurate temperature of the evaporator 5. Therefore, it is preferable that the second temperature sensor 62 measure the temperature at a position displaced upward from the lower end of the evaporator 5.

The glass tube heater 7 is arranged below the evaporator 5. The glass tube heater 7 heats the surrounding air and the evaporator 5 with radiant heat when an electric current is passed. When the frost attached to the evaporator 5 is melted by the defrosting operation, water drops downward. If the water directly adheres to the glass tube heater 7, it may cause failure or damage. Therefore, a heater cover for avoiding water is provided above the glass tube heater 7. Further, below the glass tube heater 7, a defrost water receiver 53 for receiving water generated during the defrosting operation is provided. The defrost water is collected by the defrost water receiver 53 and then flows into an evaporation tray (not shown).

Further, when the second temperature sensor 62 is provided at the lower end, the heat of the glass tube heater 7 may be directly detected, and in this case also, it is difficult to accurately measure the temperature of the evaporator 5. .. From this also, it is preferable that the second temperature sensor 62 measure the temperature at a position displaced upward from the lower end of the evaporator 5. Further, in the case of the lower end portion, the returning cold air and the water in which the frost is melted also flow down, so that they are easily affected by these. From these points as well, it is better not to be the lower end.

As shown in FIG. 4, a sheathed heater 8 meandering like the pipe 51 through which the refrigerant flows is attached to the evaporator 5 in contact with the fins 52. The sheath heater 8 is provided above the position where the second temperature sensor 62 of the evaporator 5 is attached. The sheathed heater 8 arranges an electric wire inside a heat transfer pipe made of a metal such as aluminum or copper having a high thermal conductivity, and generates Joule heat generated when an electric current is passed through the electric wire through the heat transfer pipe. The contact-type heating device heats the fins 52. In the present invention, the heater has a shape in which electric wires are arranged inside the heat transfer pipe. However, the present invention is not limited to this, and the evaporator 5 can be connected to the evaporator 5 without restricting the flow of the air flow. A configuration for heating by contact with the fin, such as a heater for heating by applying an electric current to a flat plate electrode, or a heater for heating the fin 52 by heating the metal plate in contact with the fin 52 by induction heating. It is possible to widely employ a heater configured to contact 52 and heat directly.

Next, the electrical configuration of the refrigerator Rf will be described. As shown in FIG. 3, in the refrigerator Rf according to the present invention, the damper 41, the refrigerating fan 42, the freezing fan 33, the first temperature sensor 61, the second temperature sensor 62, the glass tube heater 7, the sheath heater 8 and the compressor Comp. Is connected to the control unit Cont. The storage unit Mem and the clock unit CL are connected to the control unit Cont. The control unit Cont can always access the storage unit Mem, can store information in the storage unit Mem, and can read information from the storage unit Mem. The storage unit Mem has a configuration including a semiconductor memory such as a ROM or a RAM. In addition to these, a portable memory such as a flash memory or a hard disk may be used. In addition, the control program may be stored in the storage unit Mem, and a necessary control program may be activated as needed to perform control.

The clock unit CL is a circuit that measures time. The clock unit CL can measure the current time, the elapsed time from a predetermined time point, and the like. The control unit Cont can access the clock unit CL and can acquire the measured time information.

The control unit Cont controls each part to perform the defrosting operation. In the defrosting operation, the evaporator 5 is heated to a temperature higher than the temperature at which ice melts to melt the frost attached to the evaporator 5. Therefore, the control unit Cont stops the compressor Comp during the defrosting operation to suppress the evaporation of the refrigerant in the evaporator 5. Further, the air around the evaporator 5 is also warmed during the defrosting operation. Therefore, the control unit Cont stops the refrigerating fan 42 and the freezing fan 33 and closes the damper 41. This limits the inflow of warmed air into each storage chamber, and suppresses the temperature rise in each storage chamber.

In the refrigerator Rf, the defrosting operation is performed at regular intervals in order to secure a stable cooling capacity for a long period of time. Further, if the fins 52 are clogged due to frost, the heat exchange efficiency of the evaporator 5 is reduced, and thus the cooling of each storage chamber may be deteriorated, that is, the temperature may not be easily reduced. The defrosting operation may be performed when the temperature of the storage chamber does not drop even though the refrigeration system is operating (the compressor Comp is operating). In the following description, it is assumed that the control unit Cont regularly performs the defrosting operation.

Since the refrigerating-return cold air and the freezing-return cold air return to the evaporator 5 from the lower part, frost adheres to the evaporator 5 from the lower part. When the amount of frost is large, frost is attached to the lower portion of the evaporator 5, and when the amount of frost is large, frost is also attached to the upper portion of the evaporator 5. Although the glass tube heater 7 has a large amount of heat, since it is provided below the evaporator 5, it is effective for heating the lower portion of the evaporator 5. Since the glass tube heater 7 is heated by radiant heat, not only the lower portion of the evaporator 5 but also the upper portion thereof is heated. The sheath heater 8 is provided on the upper portion of the evaporator 5 and heats the upper portion.

Therefore, in the refrigerator Rf according to the present invention, when the amount of frost formed on the evaporator 5 is large, it is assumed that both the upper part and the lower part of the evaporator 5 are frosted, and the glass tube heater 7 and the sheath heater 8 are operated. The evaporator 5 is heated in the 1 heating mode. Thereby, the defrosting time can be shortened and the evaporator 5 can be prevented from being heated more than necessary. Further, when the amount of frost formed on the evaporator is small, it is determined that frost is formed on the lower portion of the evaporator 5, and the evaporator 5 is heated in the second heating mode in which only the glass tube heater 7 operates.

In the refrigerator Rf according to the present invention, the amount of frost formed on the evaporator 5 is calculated by the control unit Cont. Here, a method of calculating the amount of frost will be described. In the refrigerator Rf, in the refrigerator Rf, the amount of frost formed on the evaporator 5 changes depending on the usage state (outside air temperature, door opening/closing frequency, etc.). The control unit Cont uses various sensors provided in the refrigerator Rf to measure the outside temperature, the frequency of opening and closing the door, the temperature of the refrigerating compartment 21, the temperature of the lower freezing compartment 11 (upper freezing compartment 12), and the continuation of the compressor Comp. Information such as operating time, measured temperature of the first temperature sensor 61, and measured temperature of the second temperature sensor 62 is acquired. Then, these pieces of information are stored in the storage unit Mem. The storage unit Mem is provided with a table for obtaining the amount of frost formed on the evaporator 5, in addition to the storage area of these pieces of information.

For example, although the temperature of the refrigerating compartment 21 or the temperature of the lower freezing compartment 11 is unlikely to drop, it is determined that the amount of frost on the evaporator 5 is large when the continuous operation time of the compressor Comp is long. In the refrigerator Rf, it is possible to prepare a table with the temperature change of the refrigerating room 21 or the temperature change of the lower freezing room 11 and the continuous operation time of the compressor Comp as parameters, and prepare the table in the storage unit Mem in advance. Is. Further, since the outside air temperature and the door opening/closing frequency are also information related to changes in the amount of frost, a table including these pieces of information as parameters may be created. One table may include many parameters, or a plurality of types of tables may be provided.

The control unit Cont calls the information stored in the storage unit Mem and the table from the storage Mem, and calculates the frost formation amount of the evaporator 5 by calculation. For example, the control unit Cont acquires, from the storage unit Mem, the temperature change (the temperature change amount per unit time) of the lower freezer compartment 11 during a predetermined time period from the current time and the continuous operation time of the compressor Comp. .. Then, the control unit Cont refers to the table and calculates the frost formation amount of the evaporator 5 from the temperature change of the lower stage freezing compartment 11 and the continuous operation time of the compressor Comp. If there is a table that uses other information as parameters, the frost formation amount of the evaporator 5 is calculated based on that information.

Next, details of the defrosting operation will be described with reference to the drawings. FIG. 5 is a flowchart showing the defrosting operation of the refrigerator according to the present invention. The control unit Cont acquires information on each unit of the refrigerator Rf at predetermined intervals (for example, once every several tens of seconds) while the cooling device is performing the cooling operation.

The control unit Cont confirms that it is time to start defrosting (step S101). After that, the control unit Cont calculates the frost formation amount D1 of the evaporator 5 based on the table and the information of the refrigerator Rf necessary for calculating the frost formation amount of the evaporator 5 stored in the storage unit Mem (step S102). The control unit Cont confirms whether the frost formation amount D1 is larger than the threshold Th1 (step S103).

When the frost formation amount D1 is larger than the threshold Th1 (Yes in step S103), the control unit Cont determines that the frost formation amount is large and operates both the glass tube heater 7 and the sheath heater 8 in the first heating. The defrosting operation is started in the mode (step S104). In the first heating mode, the entire evaporator 5 is heated. Therefore, when the first temperature h1 of the first temperature sensor 61 that measures the temperature of the upper portion of the evaporator 5 becomes higher than a predetermined temperature a1 that is determined in advance, the defrosting operation ends.

Therefore, the control unit Cont confirms whether or not the first temperature h1 measured by the first temperature sensor 61 exceeds a predetermined temperature a1 (step S105). The control unit Cont continues to heat the evaporator 5 by the glass tube heater 7 and the sheath heater 8 until the first temperature h1 of the first temperature sensor 61 exceeds the predetermined temperature a1 (until Yes in step S105). .. When the first temperature h1 of the first temperature sensor 61 exceeds the predetermined temperature a1 (Yes in step S105), the control unit Cont ends the first heating mode and ends the defrosting operation (step S106). ).

When the frost formation amount D1 is less than or equal to the threshold Th1 (No in step S103), the control unit Cont determines that the frost formation amount is small, that is, the lower part of the evaporator 5 is mainly frosted. After that, the defrosting operation is performed in the second heating mode. However, if the defrosting operation is performed only in the second heating mode, the heating (defrosting) of the upper portion of the evaporator 5 is insufficient, and frost is gradually formed. .. Therefore, when the frost formation amount D1 is equal to or less than the threshold Th1 (No in step S103), the control unit Cont confirms whether or not all the latest three defrosting operations have been heated in the second heating mode (step S107). ). When all the last three defrosting operations are in the second heating mode (Yes in step S107), the control unit Cont starts the defrosting operation in the first heating mode (step S104). Thus, when the defrosting in the second heating mode continues for a predetermined number of times (here, three times), the frost adhering to the evaporator 5 is effectively removed by forcibly switching to the first heating mode. It is possible. The subsequent operation is as described above and will be omitted.

When at least one of the latest three defrosting operations is not in the second heating mode (No in step S107), the control unit Cont starts the defrosting operation in the second heating mode (step S108). In the second heating mode, the lower part of the evaporator 5 is heated. Therefore, when the second temperature h2 of the second temperature sensor 62 that measures the temperature of the lower portion of the evaporator 5 becomes higher than a predetermined temperature a2 that is determined in advance, the defrosting operation ends.

Therefore, the control unit Cont confirms whether the second temperature h2 measured by the second temperature sensor 62 exceeds the predetermined temperature a2 (step S109). The control unit Cont continues to heat the evaporator 5 by the glass tube heater 7 until the second temperature h2 of the second temperature sensor 62 exceeds the predetermined temperature a2 (until Yes in step S109). When the second temperature h2 of the second temperature sensor 62 exceeds the predetermined temperature a2 (Yes in step S109), the control unit Cont ends the second heating mode and ends the defrosting operation (step S110). ).

Although it is assumed that the first temperature sensor 61 and the second temperature sensor 62 constantly measure temperature at regular intervals, the present invention is not limited to this. The control unit Cont recognizes the next defrosting start time in advance, and may start the measurement from a time a certain time before the defrosting start time. For example, assuming that the defrosting operation is performed once every 24 hours, the measurement is performed by the first temperature sensor 61 and the second temperature sensor 62 at regular intervals (for example, 30 seconds) after 23 hours have passed since the previous defrosting operation. The temperatures h1 and h2 may be measured.

Regarding the threshold value Th1, the predetermined temperature a1, and the predetermined temperature a2, the refrigerator Rf is operated under several conditions, the frosted state on the evaporator 5 under each condition, and the defrosting when the defrosting operation is performed. It is a value determined by observing the frost condition. The predetermined temperature a1 and the predetermined temperature a2 may be different temperatures or the same temperature.

In the refrigerator according to the present invention, when the amount of frost formed on the evaporator 5 is large, the defrosting operation is performed in the first heating mode in which the evaporator 5 is heated by both the glass tube heater 7 and the sheath heater 8. Thereby, the heating time can be shortened as compared with the case where the heating is performed only by the glass tube heater 7. This can prevent the temperature of the lower portion of the evaporator 5 from rising too much. From this, it is possible to reduce the load when the cooling device is cooled, and it is possible to reduce power consumption. Moreover, since the defrosting operation time can be shortened and the temperature rise of the evaporator 5 can be suppressed, the temperature rise of each storage of the refrigerator Rf can be suppressed. This makes it possible to provide a refrigerator Rf capable of energy saving for a long period of time without impairing reliability.

(Second embodiment)
Another example of the refrigerator according to the present invention will be described with reference to the drawings. In the present embodiment, the power consumption is suppressed and the excessive temperature rise of the evaporator 5 is suppressed by adjusting the operation timings of the glass tube heater 7 and the sheath heater 8. The basic configuration of the refrigerator Rf is the same as that of the first embodiment. Therefore, description of the configuration of the refrigerator Rf will be omitted, and the names and reference numerals of the respective parts will be those used in the first embodiment.

The evaporator 5 re-cools the refrigeration return cold air and the freezing return cold air to generate cold air for cooling each storage chamber. Refrigerant-return cold air often contains water at a high temperature, so when the cold air returns to the evaporator 5, the contained water forms frost on the surface of the evaporator 5. In addition, frost may be formed even with the cold air returned from freezing. The refrigerated return cold air and the frozen return cold air enter the evaporator 5 from the lower part and are cooled when rising between the fins 52. Therefore, the amount of frost formed on the evaporator 5 is larger in the lower portion than in the upper portion.

Frost is the same as solid water, ie, ice, and requires latent heat of fusion when it melts from a solid to a liquid. Since the amount of frost formed on the lower portion is larger than that on the upper portion, the lower portion of the evaporator 5 is heated first, and then the upper portion is heated. This heating operation will be described with reference to the drawings. FIG. 6 is a timing chart showing the operation of the glass tube heater and the sheath heater, and FIG. 7 is a flow chart when performing the defrosting operation.

As shown in FIGS. 6 and 7, immediately after the start of the defrosting operation, the control unit Cont turns on the glass tube heater 7 (step S201). The heat from the glass tube heater 7 melts the frost attached to the lower portion of the evaporator 5. As described above, the evaporator 5 has a smaller amount of frost on the upper portion than on the lower portion. Therefore, when the glass tube heater 7 and the sheath heater 8 are simultaneously operated, the upper part of the evaporator 5 may be heated more than necessary, or defrosting of the lower part may be insufficient.

Therefore, the control unit Cont determines the frosted state of the lower portion of the evaporator 5 from the second temperature h2 of the second temperature sensor 62 that measures the temperature of the lower portion of the evaporator 5. That is, the control unit Cont confirms whether the second temperature h2 is higher than the second threshold value b2 (step S202). When the second temperature h2 is equal to or lower than the second threshold value b2 (No in step S202), heating by the glass tube heater 7 is continued.

When the second temperature h2 is higher than the second threshold value b2 (Yes in step S202), the control unit Cont determines that the frost in the lower portion of the evaporator 5 has melted to some extent and starts the operation of the sheath heater 8 ( Step S203).

Next, the control unit Cont confirms the defrosting state of the upper portion of the evaporator 5 by the sheath heater 8. Therefore, the control unit Cont confirms whether the first temperature h1 measured by the first temperature sensor 61 provided on the evaporator 5 is higher than the first threshold value b1 (step S204). When the first temperature h1 is equal to or lower than the first threshold value b1 (No in step S204), heating by the glass tube heater 7 and the sheath heater 8 is continued.

When the first temperature h1 is higher than the first threshold value b1 (Yes in step S204), the control unit Cont determines that the frost on the upper portion of the evaporator 5 has melted to some extent, and stops the sheath heater 8 (step S205). ). The control unit Cont confirms the end time of the defrosting time, and turns off the glass tube heater 7 after the end time (step S206) (step S207). By continuing to operate the glass tube heater 7 after stopping the sheath heater 8, the ice adhered to the defrost water receiver 53 can be melted.

In this way, by operating the sheath heater 8 after the operation of the glass tube heater 7, the lower part of the evaporator 5 having a large amount of frost is heated first and the upper part is heated later. As a result, the entire evaporator 5 can be heated without excess or deficiency after the completion of defrosting, and power consumption can be suppressed. Moreover, since it is possible to suppress an excessive temperature rise, it is possible to reduce the load when the cooling device is cooled. This also makes it possible to reduce power consumption. In the present embodiment, by switching between the first heating mode in which the glass tube heater 7 and the sheath heater 8 operate and the second heating mode in which the glass tube heater 7 operates, power consumption is suppressed and excess vaporization of the evaporator 5 is suppressed. The temperature rise is suppressed.

(Modification)
A modified example of the present embodiment will be described with reference to the drawings. FIG. 8 is a timing chart of a modified example of the timing chart shown in FIG. In the refrigerator Rf of the present embodiment, after the glass tube heater 7 is operated, the seeds heater 8 is operated after a certain time has elapsed. This is based on the knowledge that in the evaporator 5, the lower frost formation amount is larger than the upper frost formation amount. However, the deviation of the frost formation position may differ depending on the operating conditions.

For example, when the front surface of the evaporator 8 is uniformly or almost uniformly frosted, the temperature of the lower portion of the evaporator 5 heated by the glass tube heater 7 becomes too high only by the control of the above-mentioned flowchart. Therefore, the control unit Cont monitors the second temperature h2, which is the temperature of the lower portion of the evaporator 5, and when the second temperature h2 exceeds the third threshold value b3, turns off the glass tube heater 7 (FIG. 8). reference). Then, when the second temperature h2 becomes sufficiently lower than the fourth threshold value b4, the glass tube heater 7 is turned on again (see FIG. 8). As a result, it is possible to prevent the lower portion of the evaporator 5 from being excessively heated. The fourth threshold value b4 when turning on the glass tube heater 7 again is lower than the third threshold value b3.

In addition, there are cases where the accurate temperature cannot be detected under special circumstances, such as when only the surroundings of the first temperature sensor 61 or the second temperature sensor 62 are frosted or not frosted. In such a case as well, the control unit Cont operates the sheathed heater 8 after operating the glass tube heater 7 according to the timing chart as shown in FIG. 6 or 8. As for the delay timing of the operation start, a time delay based on the data at the time of defrosting that has been performed so far may be performed, or a predetermined time delay may be performed. Similarly, at the time of termination, even if the operation of the sheathed heater 8 is not terminated under the condition of the first temperature sensor 61 or the second temperature sensor 62, the sheathed heater 8 is terminated before the glass tube heater 7 is terminated. It may be allowed to. The timing of ending the sheath heater 8 at this time may be determined based on the data so far, or may be determined in advance.

(Third Embodiment)
Still another example of the refrigerator according to the present invention will be described. In this embodiment, the amount of frost formed on the evaporator 5 is different from that of the first embodiment. The basic configuration of the refrigerator Rf is the same as that of the first embodiment. Therefore, the description of the configuration of the refrigerator Rf will be omitted, and the names and reference numerals of the respective parts will be those used in the first embodiment.

FIG. 9 is a graph showing the relationship between the measured value of the first temperature sensor, the measured value of the second temperature sensor, and the amount of frost formed on the evaporator. In FIG. 9, the horizontal axis shows the amount of frost and the vertical axis shows the temperature. The first temperature h1 measured by the first temperature sensor 61 is shown by a broken line, and the second temperature h2 measured by the second temperature sensor 62 is shown by a solid line.

As shown in FIG. 9, both the first temperature h1 and the second temperature h2 become lower as the amount of frost increases. Then, the lowering rate is higher at the second temperature h2 than at the first temperature h1. That is, as can be seen from FIG. 9, the difference value d2 (=|h2-h1|) between the first temperature h1 and the second temperature h2 becomes smaller as the frost formation amount increases.

In the present embodiment, this is utilized to control the glass tube heater 7 and the sheath heater 8 during the defrosting operation. FIG. 10 is a flowchart of the defrosting operation of the refrigerator according to the present invention. FIG. 10 shows the state after the start of defrosting.

As shown in FIG. 10, the control unit Cont acquires the first temperature h1 and the second temperature h2 (step S301). The control unit Cont calculates the difference value d2 (=|h2-h1|) between the first temperature h1 and the second temperature h2 (step S302).

The control unit Cont determines the operation of the glass tube heater 7 and the sheath heater 8 by comparing the two types of first comparison value Cm1 and second comparison value Cm2 (Cm1>Cm2) with the difference value d2. First, the control unit Cont confirms whether the difference value d2 is larger than the first comparison value Cm1 (step S303). When the difference value d2 is larger than the first comparison value Cm1 (Yes in step S303), the control unit Cont determines that the amount of frost formed on the evaporator 5 is small, and uses only the glass tube heater 7 in the first mode. Is selected (step S304). The method of heating the evaporator 5 is the same as the second heating mode shown in the first embodiment. Therefore, details are omitted.

When the difference value d2 is less than or equal to the first comparison value Cm1 (No in step S303), the control unit Cont checks whether the difference value d2 is larger than the second comparison value Cm2 (step S305). When the difference value d2 is larger than the second comparison value Cm2 (Yes in step S305), the control unit Cont determines that the amount of frost is medium. Therefore, the control unit Cont operates the glass tube heater 7 and selects the second mode in which the sheath heater 8 operates after a lapse of time (step S306). In the second mode, the glass tube heater 7 and the sheath heater 8 are controlled similarly to the operation of the second embodiment. Therefore, details are omitted.

When the difference value d2 is equal to or smaller than the second comparison value Cm2 (No in step S305), the control unit Cont has a large amount of frost attached to the evaporator 5 or an unexpected frosting state. Then, the third mode in which both the glass tube heater 7 and the sheath heater 8 are simultaneously operated is selected (step S307). In the third mode, the sheath heater 8 is operated based on the first temperature h1 and the glass tube heater 7 is operated based on the second temperature h2 (step S308).

As described above, by controlling the operations of the glass tube heater 7 and the sheath heater 8 on the basis of the temperatures of the upper and lower portions of the evaporator 5, there are places where the evaporator 5 cannot be defrosted due to insufficient heating, It is possible to suppress the formation of a portion where the temperature of the evaporator 5 is excessively increased due to an excessive amount.

(Modification)
In the example described above, the frost formation amount of the evaporator 5 is calculated based on the difference value d2 between the first temperature h1 and the second temperature h2, and the defrost mode is switched based on the frost formation amount. This method can perform accurate defrosting operation when the evaporator 5 is uniformly frosted, that is, when the first temperature h1 and the second temperature h2 vertically overlap with each other in the graph shown in FIG.

On the other hand, the defrosting state (defrosting amount) between the upper portion and the lower portion may be different from the expected one depending on the operating method of the refrigerator Rf, the items to be stored, and the opening/closing frequency. For example, when the amount of frost on the upper part is large and the amount of frost on the lower part is small, the difference value d2 between the first temperature h1 and the second temperature h2 is large, but the amount of frost on the upper part is large. In order to handle such a case, the control unit Cont calculates the frost formation amount from each of the first temperature h1 and the second temperature h2. As a calculation method, for example, a table as shown in FIG. 9 may be used.

In this way, since the frost formation amount is calculated from each of the first temperature h1 and the second temperature h2, it is possible to detect partial frost formation on the evaporator 5. As a result, the evaporator 5 can be heated without excess or deficiency, and the defrosting operation can be reliably performed.

Although the embodiment of the present invention has been described above, the present invention is not limited to this content. The embodiments of the present invention can be modified in various ways without departing from the spirit of the invention.

The refrigerator mentioned above

Rf Refrigerator 100 Insulation box 101 Partition shelf 102 Machine room 103 Through hole Comp Compressor 1 First space 2 Second space 11 Lower freezing chamber 111 First storage case 112 Second storage case 113 Third storage case 114 Door 12 Upper freezing Chamber 121 Door 122 Storage Case 13 Ice Making Room 131 Door 132 Storage Case 133 Ice Making Machine 14 Partition 21 Refrigerating Room 22 Chilled Room 221 Storage Case 222 Front Door Section 23 Vegetable Room 231 Storage Case 232 Front Door 24 Movable Shelf 25, 26 Fixed Shelf 27 Refrigeration door 271 Door pocket 28 Partition wall 3 Cold air passage 30 Partition member 31 Cold air generation part 32 Cold air duct 321, 322, 323, 324 Discharge port 33 Freezing fan 34 Freezing return duct 4 Cold air flow path 41 Damper 42 Refrigeration fan 43 Discharge port 44 Refrigeration Return duct 441 Return opening 442 Return port 5 Evaporator 51 Pipe 52 Fin 61 First temperature sensor 62 Second temperature sensor 7 Glass tube heater 71 Heater cover Cont Control section Mem Storage section CL Clock section

Claims (5)

A refrigerator that cools a storage room with air cooled by an evaporator,
A first temperature measuring unit for measuring the temperature of the upper part of the evaporator;
A second temperature measuring part for measuring the temperature of the lower part of the evaporator;
A first heating device disposed below the evaporator to indirectly heat the evaporator;
A second heating device for heating directly in contact with at least the upper part of the evaporator;
A first temperature measuring unit and a control unit that controls the operation of the first heating device and the second heating device while acquiring the second temperature measured by the second temperature measuring unit;
The control unit starts the operation of the second heating device when the second temperature is higher than a second threshold value while the first heating device is operating, and the first temperature is higher than the first threshold value. Then, the refrigerator is controlled in the first heating mode in which the operation of the second heating device is ended. The control unit, when the second heating device is operating,
Stopping the first heating device when the second temperature reaches a third threshold higher than a second threshold;
When the second heating device is operating and the first heating device is not operating, the first heating device is operated when the second temperature is lower than a fourth threshold value lower than the third threshold value. The refrigerator according to claim 1, which is controlled. The said control part is a refrigerator of Claim 1 or Claim 2 in which the operation start of the said 2nd heating device is performed behind the operation start of the said 1st heating device in the said 1st heating mode. 4. The control unit according to claim 1, wherein in the first heating mode, the operation stop of the first heating device is performed later than the operation stop of the second heating device. refrigerator. The control unit is controllable in a second heating mode in which the first heating device is operated and the second heating device is stopped,
The control unit acquires the amount of frost formed on the evaporator from the first temperature and the second temperature ,
Wherein, when it is determined that the frost formation amount is large, the first controlled by the heating mode, wherein when it is determined that the frost quantity is small claims 1 to control in the second heating mode Item 5. The refrigerator according to any one of Items 4.

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