JP2010002071A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerator capable of improving accuracy in forecasting a frosting amount, and reducing power consumption in defrosting. <P>SOLUTION: This refrigerator includes a cooler temperature sensor 35 for determining completion of defrosting, and a temperature sensor 37 for defrosting disposed on an upper cover 53 to forecast the frosting amount. The temperature sensor 37 for defrosting is mounted on a top face of a metallic cover member of the upper cover 53 disposed between a lower part of a cooler 7 and a defrosting heater 22 while thermally kept into contact therewith. When the frosting amount is small, the amount of defrosting water dropping on the cover member is small, thus a temperature detected by the temperature sensor 37 for defrosting after the lapse of a prescribed time from the start of defrosting, is increased. As the amount of defrosting water dropping on the cover member is much when the frosting amount is much, a state of the temperature detected by the temperature sensor 37 for defrosting lower in comparison with the case when the frosting amount is small, is continued long by being cooled by the defrosting water. Accordingly, the frosting amount can be forecasted based on the temperature detected by the temperature sensor 37 for defrosting, and a temperature for determining completion of defrosting is switched according to a result of forecasting. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a defrosting operation for removing frost grown on a refrigerator cooler.

  Frost grows in the cooler due to evaporation of water from food stored in the refrigerator and intrusion of outside air when the refrigerator door is opened and closed. When frost grows on the fin surface of the cooler, the ventilation resistance gradually increases, so that heat cannot be sufficiently exchanged, resulting in a decrease in cooling performance. Therefore, it is not easy to improve the heat exchange performance on the air side by narrowing the pitch of the fins. However, there is a high need for refrigerators that can achieve both energy saving and compact and large capacity refrigerators. Higher performance of coolers by improving defrosting efficiency (shortening defrosting time, reducing frost formation, etc.) It is important in developing a refrigerator.

The conventional defroster of the cooler uses a defrost heater (for example, a glass tube heater) provided on the lower side of the cooler, and the temperature of the cooler temperature sensor installed in the cooler is constant regardless of the amount of frost formation. Continue heating to above temperature, eg, 10 ° C. This method is characterized in that there is little unmelted frost because the air in the cooler housing chamber and the periphery of the cooler are heated to defrost.
However, other than the cooler, for example, the parts around the cooler such as the fan guard of the internal fan (corresponding to the blower in the present invention) and the interior of the cooler are heated at the same time. When there is little, the ratio of the energy spent for defrosting among input energy will become small, and it will become easy to cause the temperature rise in the room | chamber interior of a refrigerator.

Since all the energy that has not been used for defrosting becomes a heat load in the cabinet, it leads to an increase in the recooling operation time after the completion of the defrosting, leading to an increase in power consumption. Therefore, in order to reduce the power consumption during defrosting, it is necessary to set the defrosting operation time according to the frosting amount in addition to reducing the frosting amount and improving the heat transfer performance during defrosting. There is.
As a method for predicting the amount of frost formation during operation of the refrigerator, for example, a method using the number of times the door is opened and closed in a certain time, the cumulative operation time of the compressor, the outside temperature, etc. is a general method used for estimating the amount of frost formation. There are also examples that are already applied to products.

In Patent Document 1, the amount of frost formation is predicted according to the number of doors opened and closed. If the amount of frost formation is smaller than the reference value of the number of doors open and closed, it is determined that the amount of frost formation is small, The defrosting time is shortened to reduce the power consumption. Moreover, in patent document 2, in order to optimize a defrost cycle, the amount of frost formation is estimated from a temperature gradient by measuring the temperature of the cooler in defrost. When the amount of frost formation is large, it takes time from the start of defrosting until the frost starts to melt, so the temperature gradient becomes gentle. Conversely, when the amount of frost formation is small, the temperature gradient becomes steep. Therefore, when the temperature gradient of the cooler during defrosting is gentle, the amount of frost formation is large, and the defrosting interval is optimized by making it shorter than the current defrosting interval.
JP-A-8-261629 JP-A-8-94234

As described above, in the conventional defrosting of refrigerators, there are many cases where the amount of frost formation is predicted based on the number of times the door is opened and closed and the cumulative operation time of the compressor. There are many cases where the defrosting completion determination temperature is set to a high value to prevent the frost from remaining undissolved so as not to cause a problem in actual use. In such a case, when there is actually less frost than expected, it is often the case that the defrost heater is energized even after all the frost has melted, and the temperature of the cooler is often increased, which increases the power consumption. It was.
The present invention has been made to solve the problems of the related art, and is to provide a refrigerator capable of improving the prediction accuracy of the amount of frost formation and reducing the power consumption during defrosting. .

  The refrigerator according to claim 1 of the present invention includes a refrigeration cycle in which a compressor, a condenser, a throttle, and a cooler are sequentially connected by a refrigerant pipe, a blower that circulates air cooled by the cooler, and the cooler In the refrigerator provided with the defrosting heater provided below, a defrosting temperature sensor is provided between the cooler and the defrosting heater.

  According to invention of Claim 1, since the temperature sensor for defrosting is provided between the said cooler and the said defrost heater, the defrost which the frost adhering to the cooler by a defrost heater melt | dissolved was formed. It becomes possible to detect the temperature change around the defrosting temperature sensor due to water.

  The refrigerator of the invention described in claim 2 of the present invention is provided with a cover member that covers the top of the defrost heater in addition to the configuration of the invention described in claim 1, and the temperature sensor for defrost is the cover. It is attached so that the temperature of a member may be detected.

  Since the cover member receives dripping of defrost water from the cooler at the time of defrosting, detecting the temperature of the cover member with the temperature sensor for defrosting allows the amount of frost formation on the cooler at the beginning of the defrosting operation. It is possible to detect a change in the amount of defrost water due to the progress of the defrosting operation from the temperature detected by the defrosting temperature sensor.

  The refrigerator of the invention described in claim 3 of the present invention is characterized in that, in addition to the configuration of the invention described in claim 2, the defrost heater is attached so as to be in thermal contact with the cover member. .

  Since the cover member receives dripping water from the cooler during defrosting, the cover member directly detects the temperature of the cover member with the temperature sensor for defrosting, thereby frosting the cooler at the beginning of the defrosting operation. It becomes possible to detect a change in the amount of defrost water due to the amount of the amount and the progress of the defrosting operation from the temperature detected by the defrosting temperature sensor.

  ADVANTAGE OF THE INVENTION According to this invention, the prediction accuracy of the amount of frost formation can be improved, and the refrigerator which can aim at reduction of the power consumption at the time of defrost can be provided.

An embodiment of a refrigerator according to the present invention will be described with reference to the drawings.
FIG. 1 is a front external view of a refrigerator according to the present embodiment, and FIG. 2 is an XX longitudinal sectional view in FIG. 1 showing a configuration inside the refrigerator. FIG. 3 is a front view illustrating a configuration inside the refrigerator, and is a diagram illustrating the arrangement of the cold air duct and the outlet.
As shown in FIG. 1, the refrigerator 1 of this embodiment is comprised from the upper part from the refrigerator compartment 2, the ice making room 3, the upper freezer compartment 4, the lower freezer compartment 5, and the vegetable compartment 6. As shown in FIG.

The refrigerating room 2 includes front and rear refrigerating room doors 2a and 2b which are divided into left and right sides, and the ice making room 3, the upper freezing room 4, the lower freezing room 5, and the vegetable room 6 are respectively drawer-type ice making room doors. 3a, an upper freezer compartment door 4a, a lower freezer compartment door 5a, and a vegetable compartment door 6a. Hereinafter, the refrigerator compartment doors 2a and 2b, the ice making compartment door 3a, the upper freezer compartment door 4a, the lower freezer compartment door 5a, and the vegetable compartment door 6a are simply referred to as doors 2a, 2b, 3a, 4a, 5a, and 6a.
The refrigerator 1 includes a door sensor (not shown) that detects the open / closed state of each door of the doors 2a, 2b, 3a, 4a, 5a, and 6a, and a state determined to be the door open state for a predetermined time, for example, 1 minute. When the operation is continued, an alarm (not shown) for notifying the user, a temperature setting unit (not shown) for setting the temperature of the refrigerator compartment 2 and the temperature of the upper freezer compartment 4 and the lower freezer compartment 5 are provided.

As shown in FIG. 2, the outside of the refrigerator 1 and the inside of the refrigerator are separated by a heat insulating box 10 formed by filling a foam heat insulating material (foamed polyurethane). The heat insulating box 10 of the refrigerator 1 has a plurality of vacuum heat insulating materials 25 mounted thereon.
The refrigerator compartment 2 is separated from the refrigerator compartment 2 by the heat insulating partition wall 28, and the upper freezer compartment 4 and the ice making chamber 3 (see FIG. 1, the ice making chamber 3 is not shown in FIG. 2). The lower freezer compartment 5 and the vegetable compartment 6 are separated.
A plurality of door pockets 32 are provided on the inner side of the doors 2a and 2b (see FIG. 1, the refrigerator compartment door 2b is not shown in FIG. 2). The refrigerator compartment 2 is partitioned into a plurality of storage spaces in the vertical direction by a plurality of shelves 36.

  As shown in FIG. 2, the upper freezer compartment 4, the lower freezer compartment 5, and the vegetable compartment 6 are integrated with doors 3a, 4a, 5a, 6a provided in front of the respective compartments, and storage containers 3b, 4b, 5b. , 6b are provided, and the storage containers 4b, 5b, 6b can be pulled out by placing a hand on a handle portion (not shown) of the doors 4a, 5a, 6a and pulling it out to the front side. Similarly, the ice making chamber 3 shown in FIG. 1 is provided with an unillustrated storage container (indicated by (3b) in FIG. 2) integrally with the door 3a. The container 3b can be pulled out by pulling it out.

As shown in FIG. 2, the cooler 7 is provided in a cooler storage chamber 8 provided substantially at the back of the lower freezing chamber 5, and an internal fan (blower) 9 provided above the cooler 7. The air cooled by heat exchange with the cooler 7 (cold air, hereinafter, low temperature air cooled by the cooler 7 is referred to as cold air) is a refrigerator compartment air duct 11, a vegetable room air duct (not shown) (not shown). 3), the freezer compartment 2, the vegetable compartment 6, the upper freezer compartment 4, the lower freezer compartment 5, and the ice compartment 3 through the upper freezer compartment air duct 12, the lower freezer compartment air duct 13, and the ice making compartment air duct (not shown). Sent to each room. Air blowing to each room is controlled by opening and closing the refrigerator compartment damper 20 and the freezer compartment damper 50.
Incidentally, the air ducts to the refrigerator compartment 2, the ice making room 3, the upper freezer compartment 4, the lower freezer compartment 5, and the vegetable compartment 6 are provided on the back side of each room of the refrigerator 1 as indicated by broken lines in FIG. Yes.

Specifically, when the refrigerator compartment damper 20 is in the open state and the freezer compartment damper 50 is in the closed state, the cold air is sent to the refrigerator compartment 2 from the air outlets 2c provided in multiple stages via the refrigerator compartment air duct 11. It passes through the vegetable room ventilation duct (refer FIG. 3) branched from the room ventilation duct 11, and is sent to the vegetable room 6 from the blower outlet 6c.
Note that the cold air that has cooled the refrigerator compartment 2 is viewed from the front of the cooler storage compartment 8 (see FIG. 4) through the refrigerator outlet return duct 16 from the return port 2d provided on the lower surface of the refrigerator compartment 2, for example. For example, return to the lower right side. The return air from the vegetable compartment 6 returns to the lower part of the cooler storage compartment 8 through the return opening 6d.

Although the freezer damper 50 is omitted in FIG. 3, when the freezer damper 50 is in an open state, the cold air heat-exchanged by the cooler 7 is not shown in the drawing by an internal fan 9 and an ice making chamber air duct or upper freezer The air is blown from the blowout ports 3c and 4c to the ice making chamber 3 and the upper freezer compartment 4 through the blower duct 12, and is blown from the blowout port 5c to the upper freezer chamber 4 through the lower freezer compartment blower duct 13.
The cold air that has cooled the upper freezer room 4, the lower freezer room 5, and the ice making room 3 returns to the cooler storage room 8 through the freezer return port 17 provided in the lower part of the lower freezer room 5.

Further, a defrost heater 22 is installed below the cooler 7, and in order to prevent the defrost water E (see FIG. 5) from dropping on the defrost heater 22 above the defrost heater 22. An upper cover 53 is provided.
After the defrost water E generated by the frost adhering to the wall of the cooler 7 and the surrounding cooler storage chamber 8 being melted by the defrost flows into the tub 23 provided at the lower part of the cooler storage chamber 8. Then, it reaches the evaporating dish 21 disposed in the machine room 19 to be described later through the drain pipe 27 and is evaporated by the heat of the condenser to be described later.

Further, the cooler 7 has a cooler temperature sensor 35 (in FIG. 3, the cooler temperature sensor 35 does not necessarily indicate an accurate mounting location), and the refrigerating room 2 has the refrigerating room temperature sensor 33 and the lower freezing room 5. Are respectively provided with a freezer temperature sensor 34, the temperature of the cooler 7 (hereinafter referred to as the cooler temperature), the temperature of the refrigerator compartment 2 (hereinafter referred to as the refrigerator temperature), and the lower freezer compartment 5. The temperature (hereinafter referred to as freezer compartment temperature) can be detected.
Incidentally, the refrigerator 1 includes an outside air temperature sensor and an outside air humidity sensor (not shown) that detect a temperature and humidity environment (outside air temperature, outside air humidity) outside the refrigerator. A vegetable room temperature sensor 33 </ b> A may also be arranged in the vegetable room 6.
In the present embodiment, a defrosting temperature sensor 37 (see FIG. 4) is also attached to the upper cover 53. Detailed mounting locations of the cooler temperature sensor 35 and the defrosting temperature sensor 37 will be described later.

A machine room 19 is provided on the lower back side of the heat insulating box 10. The machine room 19 contains a compressor 24 and a condenser (not shown in FIG. 3). The condenser is ventilated.
Incidentally, in this embodiment, isobutane is used as a refrigerant, and the amount of refrigerant enclosed is as small as about 80 g.

  A control board 31 on which a CPU, a memory such as a ROM and a RAM, an interface circuit and the like are mounted is arranged on the upper surface side of the ceiling wall of the refrigerator 1. The temperature sensor 35, the refrigerator temperature sensor 33, the freezer temperature sensor 34, the cooler temperature sensor 35, the defrosting temperature sensor 37, and the open / closed states of the doors 2a, 2b, 3a, 4a, 5a and 6a are detected. Connected to the door sensor described above, a temperature setter (not shown) provided on the inner wall of the refrigerator compartment 2, a temperature setter (not shown) provided on the inner wall of the lower freezer compartment 5, etc. ON / OFF control of the machine 24, control of the respective actuators (not shown) for individually driving the refrigerator compartment damper 20 and the freezer compartment damper 50, the internal fan 9 On / off control or rotational speed control, the outside-compartment blower ON / OFF control and control of the rotational speed control and the like, a control such as an alarm on / off to notify the above-mentioned door open performed.

(Configuration of cooler storage room)
Next, the configuration of the cooler storage chamber 8 will be described with reference to FIGS.
4 is a front partial enlarged view of the cooler and its peripheral part, FIG. 5 is a side partial enlarged view of the cooler and its peripheral part, and FIG. 6 is a detailed perspective view of the defrosting heater.
The cooler 7 is configured by connecting a plurality of units each having a plurality of fins 7b attached to the cooler pipe 7a. In FIG. 4, the cooler 7 has a seven-stage configuration with respect to the flow direction of the cool air returning to the inside of the refrigerator. It is installed on the back of the back side wall 5d (see FIG. 5) of the chamber 5. In the cooler inlet pipe 55, the refrigerant compressed by the compressor 24 (see FIG. 2) is radiated by a condenser (not shown) and connected to a refrigerant pipe through a throttle (not shown), and the cooler outlet pipe 56 is compressed. It is connected to the suction side of the machine 24. In the middle of the cooler outlet pipe 56, a header 57 for adjusting the refrigerant amount is provided.
A compressor 24, a condenser and a throttle (not shown), and a cooler 7 that are sequentially connected by a refrigerant pipe are generally called a refrigeration cycle.

As shown in FIG. 4, the refrigerating chamber return duct 16 is provided on the right side of the cooler housing chamber 8 that houses the cooler 7 via a partition wall, and is indicated by a broken line arrow D from the refrigerating chamber 2 (see FIG. 3). The refrigerating room return air shown flows through the refrigerating room return duct 16 into the cooler 7 from the lower right side as viewed from the front. On the other hand, the ice compartment 3 (see FIG. 3), the upper freezer compartment 4 (see FIG. 3) and the lower freezer compartment 5 (see FIG. 3) are cooled and passed through the freezer return port 17 (see FIG. 3). The return air flows from the lower front part of the cooler 7 as indicated by the solid line arrow C.
As shown in FIG. 5, a defrost heater 22 is provided below the cooler 7 and above the eaves 23 that temporarily receives the defrost water E.

  Returning to FIG. 4, the cooler temperature sensor 35 is attached to the cooler inlet pipe 55 near the unit of the cooler 7 in contact with the cooler inlet pipe 55, and the cooler temperature sensor 35 is connected to the signal line. To the control board 31 (see FIG. 2). The place where the cooler temperature sensor 35 is installed should be in contact with the cooler 7 in the vicinity of the place where frost can be finally melted, and is not necessarily limited to the position of the cooler inlet pipe 55 near the unit of the cooler 7. is not. Preferably, the cooler 7 is installed in thermal contact with the fins 7b in the region B of the uppermost unit of the cooler 7.

  As shown in FIG. 6, the defrosting heater 22 is comprised from the heater part 22a and the radiation fin 22b. For example, a glass tube heater may be used as the heater unit 22a, but a heat radiating fin 22b is provided in order to keep the temperature of the glass tube surface below a certain temperature. Between the defrost heater 22 and the cooler 7, an end member 53 b fixed to both ends of the defrost heater 22, and a reinforcement disposed on the top of the defrost heater 22 so as to be separated in the axial direction of the defrost heater 22. An upper cover 53 including a mountain-shaped cover member 53a supported by the member 53c is provided.

  The upper cover 53 protects the refrigerant from being blown directly onto the high-temperature heater portion 22a even if the refrigerant leaks from the refrigerant pipe so as not to cause a fire. In this embodiment, the cover member 53a For example, it is comprised with the stainless steel plate. Further, when a glass tube heater is used for the heater portion 22a, the defrost water E (see FIG. 5) directly touches the glass tube, and the glass tube may be damaged by thermal shock. Moreover, it also has a role which protects so that the defrost water E may not be dripped directly at the heater part 22a. Therefore, the cover member 53a has a lower projection area substantially the same as the lower projection surface of the cooler 7, and is positioned so as to include the lower projection surface of the cooler 7.

A defrosting temperature sensor 37 is installed on the upper surface of the cover member 53a near the refrigeration chamber return duct 16 (see FIG. 4) and brought into contact with the upper surface of the cover member 53a by the holder 38 made of the same material as the cover member 53a. Has been. Similarly to the cooler temperature sensor 35, the defrosting temperature sensor 37 is also connected to the control board 31 (see FIG. 2) via a signal line.
When heated by the defrost heater 22, the temperature of the cover member 53 a reaches about 140 ° C. at maximum, so that the defrosting temperature sensor 37 needs to use a high temperature type sensor.
The cover member 53a is also a temperature detection member serving as a medium for receiving the defrost water dripped from the cooler 7 during the defrosting operation and causing the defrosting temperature sensor 37 to detect the defrosting progress state. .

Further, the lateral width (left / right width) of the cover member 53a is equal to or greater than the lateral width of the defrost heater 22 (see FIG. 4), and is equal to or greater than the lateral width (left / right width) of the cooler 7. This is the end (see FIG. 4).
Since the cover member 53a is provided between the heater portion 22a and the cooler 7 and the radiating fin 22b is in thermal contact with the reinforcing member 53c, the temperature of the cover member 53a is high immediately after the start of defrosting. For example, the temperature is about 140 ° C.

  By the way, the distribution of the frost that grows in the cooler 7 is that the return air from the refrigerator compartment 2 (see FIG. 3) contains more moisture, so the influence of the inflow of the refrigerator compartment return air is large. It has been empirically known that the amount of frost formation on the side where 16 is installed, that is, the region B on the right side of the cooler 7 is larger than the region A on the left side of the cooler 7 in FIG.

(Temperature detection behavior of defrosting temperature sensor)
Next, the temperature detection of the defrosting temperature sensor 37 when the frost that has grown on the fins 7 b of the cooler 7 is solved by the heat of the defrost heater 22 installed below the cooler 7 with reference to FIG. 5. The behavior will be described.
Immediately after the start of defrosting, the defrost water E does not drip, so that the heat from the defrost heater 22 is transmitted to the cover member 53a by radiation or heat transfer, and further to the defrosting temperature sensor 37 by heat conduction. Therefore, although the cover member 53a is heated and the temperature rapidly rises, the defrost water E is dropped from above the cover member 53a, so that the cover member 53a is cooled. The defrosting proceeds from the cooler pipe 7a and the fin 7b of the lowermost unit of the cooler 7 that is close to the defrosting heater 22, and the frost that has grown on the fin 7b of the uppermost unit of the cooler 7 is finally melted. .

  That is, since the cover member 53a has substantially the same width as the cooler 7, even if the temperature of the defrost water E is not directly measured by the defrosting temperature sensor 37, the cover member 53a must be defrosted water. Since E drops and cools, the cooling effect of the cover member 53a by the defrost water E can be detected by detecting the temperature of the cover member 53a. Therefore, the temperature change of the cover member 53a after the start of the defrosting is detected, and the amount of frost formation is predicted from the temperature at a predetermined time after the start of the defrosting. The detailed operation will be described later in the description of the flowchart of the defrost control in FIG.

(Defrost control)
Next, control of the defrosting operation in this embodiment will be described.
FIG. 7 is a flowchart showing a control flow of the defrosting operation. This control is performed on the control board 31 (see FIG. 2).
In step S1, when the refrigerator 1 is started, IFLAG = 0 is set as an initial condition. This flag indicates whether or not defrosting with a small amount of frosting has been performed in the nearest defrosting operation. If defrosting with a small amount of frosting is performed, IFLAG = 1, otherwise. IFLAG = 0. In step S2, one of the normal cooling operation modes, “freezer cooling operation”, “refrigeration chamber cooling operation”, and “refrigeration chamber / freezer simultaneous cooling operation” is selected according to the temperature of the refrigerator compartment and the temperature of the freezer compartment. Accordingly, the cooling operation is performed by controlling the opening and closing of the refrigerator compartment damper 20 and the freezer compartment damper 50 accordingly.
In step S3, the defrosting start condition is determined by the number of doors 2a, 2b, 3a, 4a, 5a, 6a opened / closed, the cumulative operation time of the compressor 24, the outside temperature, the outside humidity, etc. Whether or not it is established is determined at a predetermined cycle. If it is determined that the defrosting start condition is satisfied (Yes), the process proceeds to step S4. If not, the process returns to step S2 to continue the cooling operation.

In step S4, it is checked whether IFLAG = 1. If IFLAG = 1 (Yes), the process proceeds to step S14. If IFLAG # ≠ 1 (No), the process proceeds to step S5. And the timer t is started (step S5) and it supplies with electricity to the defrost heater 22 (step S6).
Incidentally, when the defrost heater 22 is energized, the compressor 24 and the internal fan 9 are stopped, and the refrigerator compartment damper 20 and the freezer compartment damper 50 are closed.

  Next, in step S7, it is checked whether or not the timer t is equal to or longer than the frost formation amount determination time t1 (t ≧ t1). If the timer t is equal to or longer than the frost amount determination time t1 (Yes), the process proceeds to step S8, and if not (No), the process returns to step S6. In step S8, the timer t is reset, and whether or not the temperature T2 detected by the defrosting temperature sensor 37 (the temperature detected by the defrosting temperature sensor) is equal to or higher than the frosting amount determination temperature Tth (T2 ≧ Tth). Is checked (step S9). If T2 ≧ Tth (Yes), the process proceeds to step S10, and if not, the process proceeds to step S14.

In step S10, it determines with "the amount of frost formation being small", and then sets defrost completion determination temperature TL, for example, 1 degreeC (step S11). In step S12, it is checked whether or not the temperature T1 detected by the cooler temperature sensor 35 (temperature detected by the cooler temperature sensor) is equal to or higher than the defrosting completion determination temperature TL (temperature T1 ≧ TL). If the temperature T1 ≧ TL (Yes), the process proceeds to Step S13. If not (No), Step S12 is repeated to continue defrosting.
In step S13, IFLAG = 1 is set, and then defrosting is terminated (step S18). When the defrosting is completed, the defrosting heater 22 is deenergized, the compressor 24 is turned on, and the cooler 7 and the cooler storage chamber 8 are waited for cooling for a predetermined elapsed time. Then, it returns to step S2 and starts a cooling operation.

In the case of Yes in step S4 or in the case of No in step S9, the process proceeds to step S14, where it is determined that “the amount of frost formation is large”, and then the defrost completion determination temperature TH that is higher than the defrost completion determination temperature TL. For example, 10 ° C. is set (step S15). In step S16, it is checked whether or not the temperature T1 detected by the cooler temperature sensor 35 is equal to or higher than the defrosting completion determination temperature TH (temperature T1 ≧ TH). If temperature T1 ≧ TH (Yes), the process proceeds to step S17. If not (No), step S16 is repeated to continue defrosting.
In step S17, IFLAG = 0 is set, and then defrosting is terminated (step S18). When the defrosting is completed, the defrosting heater 22 is deenergized, the compressor 24 is turned on, and the cooler 7 and the cooler storage chamber 8 are waited for cooling for a predetermined elapsed time. Then, it returns to step S2 and starts a cooling operation.

  Steps S <b> 1 and S <b> 4 to S <b> 18 in the flowchart of the present embodiment constitute “defrost control means”.

FIG. 8 is a diagram showing the transition of the detected temperatures of the cooler temperature sensor 35 and the defrosting temperature sensor 37 after the start of defrosting when the amount of frost formation is large, the horizontal axis is time (min), and the vertical axis is Temperature (° C) is shown. FIG. 9 is a diagram showing the transition of the detected temperature of the cooler temperature sensor 35 and the defrosting temperature sensor 37 after the start of defrosting when the amount of frost formation is small, the horizontal axis is time (min), and the vertical axis is Temperature (° C) is shown.
In FIGS. 8 and 9, the curve x indicates the transition of the temperature detected by the cooler temperature sensor 35, and the curve y indicates the transition of the temperature detected by the defrosting temperature sensor 37. In FIGS. 8 and 9, curves x1, x2, and x3 indicate changes in temperature measured with reference to temperature sensors at the upper, middle, and lower portions at the vertical position of the cooler 7, respectively.

  When the amount of frost formation is large, as shown in FIG. 8, when the defrost heater 22 is energized at time 0, the temperature detected by each temperature sensor rises, but is brought into thermal contact with the cover member 53a indicated by the curve y. The detected temperature of the defrosting temperature sensor 37 rises most rapidly because there is no cooling by the defrosting water E yet. Thereafter, the cover member 53a is cooled by the dripping of the defrost water E, but the tendency is greatly different from the case where the amount of frost formation shown in FIG. 9 is small. Since the amount of frost formation is large, even if the surface frost starts to melt, the temperature (curve x, x1, x2, x3) detected by the temperature sensor fixed to the cooler 7 still shows a temperature rise to 0 ° C. At this stage, the defrost water E is dripped onto the cover member 53a and cooled and there is also a lot of defrost water E. Therefore, the temperature of the cover member 53a shown by the curve y tends to be lower than the case where the amount of frost formation is small. There is a time zone that changes at a stable temperature. Thereafter, when the temperature of the cooler 7 reaches approximately 0 ° C., the curve y starts to gradually increase as the dripping amount of the defrost water E decreases. Thereafter, a temperature state in which the amount of the defrosted water E is substantially equilibrated in a state where the amount of the defrosted water E is less than that in the initial stage continues for a while.

  The temperature T1 (cooler temperature) detected by the cooler temperature sensor 35 rises substantially linearly for a while from the start of defrosting as shown by the curve x in FIG. The temperature is approximately 0 ° C., and the refrigerant temperature in the cooler inlet pipe 55 also rises, and starts rising later than the curves x1, x2, and x3. And finally exceeds the defrosting completion determination temperature TH indicated by the one-dot chain line.

On the other hand, when the amount of frost formation is small, as shown in FIG. 9, when the defrost heater 22 is energized at time 0, the temperature detected by each temperature sensor rises, but the cover member 53a indicated by the curve y The detection temperature T2 of the defrosting temperature sensor 37 brought into thermal contact shows the most rapid increase, and then the dripping of the defrosting water E starts, but since the dripping amount of the defrosting water E is small, the temperature rises gradually. After the change, the equilibrium state is reached at a higher temperature.
The temperature T1 (cooler temperature) detected by the cooler temperature sensor 35 rises substantially linearly for a while immediately after the start of defrosting, as shown by the curve x in FIG. The temperature rises and the temperature of the refrigerant in the cooler inlet pipe 55 also rises, and the temperature rise starts later than the curves x1, x2, and x3. And finally exceeds the defrosting completion determination temperature TL indicated by the one-dot chain line.

  Here, when the frost amount determination time t1 is appropriately set, a large difference occurs in the temperature T2 detected by the defrosting temperature sensor 37 at the time t1, and the temperature T2 at that time is determined in advance by an experiment. Whether the amount of frost formation is small or large is predicted based on whether the temperature is equal to or higher than the temperature Tth, and one of the defrosting completion determination temperatures TL and TH prepared in advance is determined based on the prediction result. Set as.

Assuming that the average usage of the refrigerator 1 at home is assumed, the case where the frost amount is predicted to be large and the case where the frost amount is small are predicted to be approximately half. A frost amount determination temperature Tth is set.
As a result, when it is determined that the amount of frost formation is small, the defrosting completion determination temperature TL having a value smaller than the defrosting completion determination temperature TH is used, so that the defrosting time can be shortened as shown in FIG.

FIG. 10 is a diagram showing the relationship of the defrosting time required for the amount of frost formation. The defrosting time when defrosting completion is determined at the defrosting completion determination temperature TH based on the temperature detected by the cooler temperature sensor 35 is indicated by a circle mark, and the average value curve is indicated by a solid line Y0. . As the frost amount increases, the defrost time increases linearly, and when the frost amount exceeds a certain value, the defrost time tends to increase rapidly.
The air in the peripheral part is heated by the defrost heater 22 and rises in the peripheral part of the cooler 7 to which frost is attached by natural convection. However, as the amount of frost increases, the ventilation resistance increases. This is because convection is suppressed. Further, since the defrosting completion determination temperature TH is the same regardless of the amount of frost formation, when the amount of frost formation is small, the energy consumed for the defrosting is relatively small with respect to the total input energy.

When the amount of frost formation is small according to the flowchart shown in FIG. 7, assuming that the defrosting completion determination temperature value is the defrosting completion determination temperature TL lower than the defrosting completion determination temperature TH, as indicated by the broken line Y1 in FIG. 10. The defrosting time can be shortened.
Regarding the frost formation amount (g) for classifying some cases of frost formation amount, the frost formation determination temperature Tth, and the frost formation determination time t1 for detecting the temperature of the cover member 53a compared with the frost formation determination temperature Tth, It is determined by collecting data through experiments.

  In addition, assuming an average usage situation of the refrigerator 1 at home, the case where it is predicted and determined that the amount of frost formation is large and the case where the determination is determined that the amount of frost formation is small are approximately half. When the frost amount determination temperature Tth is set, the time of the difference between the solid line Y0 and the broken line Y1 is applied to half of the defrosting luck, and the reduction of the defrosting time is great for energy saving of the refrigerator 1. Give effect.

  Further, once defrosting is performed by predicting that the amount of frost formation is small, the flag IFLAG = 1 is set in step S13, and the process proceeds from step S4 to step S14 for the next defrosting. Since the defrosting operation when the amount of frost formation is large is performed, the defrosting operation when the amount of frost formation is small can be repeated to prevent the frost from remaining unmelted.

(Modification of setting method of defrosting completion determination temperature)
Next, the modification of the setting method of the defrost completion determination temperature in this embodiment is demonstrated.
In this embodiment, the setting method of the defrost completion determination temperature is detected at the defrosting amount determination time t1 after the start of defrosting by the defrosting temperature sensor 37, and the detected temperature T2 is detected. Defrosting completion determination is different depending on whether the frost formation amount is low or high depending on whether or not the frost formation determination temperature Tth or higher, and when it is predicted that the frost formation amount is low and when the frost formation amount is high. Although the temperature is set, the present invention is not limited to this.

  For example, the standard defrosting completion determination temperature is set to TH, and a correction in which the defrosting completion determination temperature is decreased from TH as the detection level increases according to the temperature level of the detection temperature T2 at the frosting amount determination time t1. The defrost completion determination temperature may be corrected and calculated using table look-up data so that the minimum defrost completion determination temperature is TL.

  As described above, according to the present embodiment, the cover member 53a, which is a temperature detection member, is configured to have a length substantially equal to the lateral width of the cooler 7, and has a size approximately equal to the downward projection area of the defrost heater 22. is there. Immediately after the start of defrosting, the temperature of cover member 53a (see FIG. 5) rises rapidly due to the heating of defrosting heater 22 (see FIG. 5). Thereafter, when the frost starts to melt and defrosted water E (see FIG. 5) starts to be generated, it drops on the cover member 53a, so that the temperature of the cover member 53a is cooled and the temperature rise gradually becomes milder. Even if the defrosting water E does not drip directly on the defrosting temperature sensor 37 (see FIG. 5), the cover member 53a is cooled by the defrosting water E. The dripping of the defrost water E onto the member 53a can be detected.

  When the amount of frost formation is small, the amount of defrost water E dripping onto the cover member 53a is small, so the temperature detected by the defrosting temperature sensor 37 is high, and the temperature until the temperature of the cover member 53a reaches a predetermined value. The time is short. On the other hand, when the amount of frost formation is large, the amount of defrost water E dripping onto the cover member 53a is large. Therefore, although the temperature detected by the defrost temperature sensor 37 once becomes high, the cover member 53a is defrosted by the defrost water E. Is cooled and the low temperature state continues longer than when the amount of frost formation is small.

  Therefore, the amount of frost formation can be predicted more accurately during defrosting by the cover member 53a. And based on the result which the amount of frost formation was estimated by the temperature sensor 37 for defrosting, and the temperature which the cooler temperature sensor 35 (refer FIG. 4) provided in the periphery of the cooler 7 or the cooler 7 detected. Thus, the completion of defrosting can be determined more accurately.

  Further, since either the defrosting completion determination temperature TL or the defrosting completion determination temperature TH of the cooler temperature sensor 35 is set or the defrosting completion determination temperature is corrected, the cover member 53a and the defrosting temperature sensor 37 are corrected. Is set to a low defrosting completion determination temperature TL, for example, 1 ° C., and when it is predicted that the frosting amount is large, the defrosting completion determination temperature TH is set. High, for example, can be set to 10 ° C. to prevent frost from remaining unmelted, an appropriate defrosting completion determination temperature can be set according to the amount of frost formation, and the energization time of the useless defrosting heater 22 can be reduced. It can be lost. As a result, it can contribute to the energy saving operation of the refrigerator 1.

  Incidentally, the refrigerator compartment return duct 16 (see FIG. 4) side of the cooler 7 is exposed to return air with high humidity, and the amount of frost formation is larger than the side exposed to the freezer compartment return air. And, by providing the defrosting temperature sensor 37 on the refrigerator duct return duct 16 side in the projection surface below the cooler 7, the defrosting temperature sensor 37 substantially unfreezes the frost in the cooler 7. The temperature is unlikely to rise until it is cut, and this is a suitable side for accurately predicting the amount of frost on the cooler 7, so that the prediction accuracy of the amount of frost is improved.

  In the flowchart shown in FIG. 7, the defrosting of the next time when the defrosting temperature sensor 37 determines that the amount of frost formation is small and the defrosting completion determination temperature is set or corrected low to complete the defrosting is the defrosting. By always setting the completion determination temperature to a high value when the amount of frost formation is large and ending the defrosting operation, it is possible to prevent frost from remaining unmelted.

<Modification>
(Modification of the method for attaching the defrosting temperature sensor to the cover member)
Next, a modification of the method for attaching the defrosting temperature sensor 37 to the cover member 53a will be described.
When heated by the defrost heater 22, the temperature of the cover member 53a reaches a maximum of about 140 ° C. Therefore, it is necessary to use a high temperature type sensor for the defrost temperature sensor 37, which may increase the cost. Therefore, in the present modification, the temperature detected by the defrosting temperature sensor 37 is lowered while maintaining the relative temperature relationship between when the amount of frost formation is small and when the amount of frost formation is large.
(First modification)
FIG. 11 shows a first modification of the installation method of the defrosting temperature sensor 37. In the present modification, a holder 38 for bringing the defrosting temperature sensor 37 into thermal contact is attached to the upper surface of the cover member 53a via a heat insulating member 39. About the same structure as embodiment, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
Since the heat insulating member 39 is interposed, the temperature detected by the defrosting temperature sensor 37 can be lower than 140 ° C., and the cost of the defrosting temperature sensor 37 can be reduced.

(Second modification)
FIG. 12 shows a second modification of the installation method of the defrosting temperature sensor 37. In this modification, a holder 38A is used that includes a vertical portion 41a and a flat portion 41b, and has an attachment member 41 in which a plate material is bent in an L shape. And the lower end of the vertical part 41a is fixed to the edge part by the side of the refrigerator compartment return duct 16 of the cover member 53a. The defrosting temperature sensor 37 is brought into thermal contact with the upper surface of the flat portion 41b. In order to lower the temperature detected by the defrosting temperature sensor 37, the flat surface portion 41b is separated from the upper surface of the cover member 53a by a distance h, and a part of the vertical portion 41a is removed to provide an opening 38a. The area of the portion 41a is reduced. With such a structure, the temperature detected by the defrosting temperature sensor 37 can be lowered. Since the area of the vertical portion 41a is reduced, it is possible to prevent an increase in ventilation resistance of the return air from the refrigerator compartment during the cooling operation.

(Third Modification)
FIG. 13 shows a third modification of the installation method of the defrosting temperature sensor 37. In the present modification, a recess 44 is provided on the cover member 53a on the refrigerator return duct 16 side, and a defrosting temperature sensor 37 is disposed therein. The recess 44 has a structure in which a wall is provided on the front side in FIG.
At the time of defrosting, the defrosting water E is dripped at the cover member 53a from the fin 7b etc. of the cooler 7. The cover member 53a is heated by the defrost heater 22 installed on the lower side, but the temperature detected by the defrost temperature sensor 37 installed on the cover member 53a is cooled by the defrost water E accumulated in the recess 44. Therefore, the temperature decreases. Further, since the defrost water E remaining in the concave portion 44 is frozen during the cooling operation, heat is taken away to melt the ice in the concave portion 44 at the next defrosting. Therefore, the temperature detected by the defrosting temperature sensor 37 can be lowered.
Further, a notch 45 is provided to adjust the water surface in the recess 44, so that the defrost water E in the recess 44 rises upward from the recess 44 so that ice does not grow.

  Since the temperature detected by the defrosting temperature sensor 37 differs depending on the installation method of the defrosting temperature sensor 37 of the first to third modifications described above, at least the frosting amount determination temperature Tth is changed to the modification. Decide accordingly.

In the above-described embodiment and the first to third modifications thereof, the cover member 53a, which is a temperature detection member that detects the temperature of the defrosting temperature sensor 37, is assembled integrally with the defrosting heater 22. However, the present invention is not limited to this.
For example, in the cooler storage chamber 8 (see FIG. 2), the upper cover 53 is supported so that the lowermost unit of the cooler 7 suspends the upper cover 53 from above, and below the cooler 7. Thus, the upper cover 53 is arranged separately from the defrosting heater 22 so as to be spaced apart upward from the heater portions 22a and the radiation fins 22b constituting the defrosting heater 22.

It is a front external view of the refrigerator which concerns on embodiment of this invention. It is a longitudinal cross-sectional view showing the structure in the store | warehouse | chamber of a refrigerator. It is a front view showing the structure in the store | warehouse | chamber of a refrigerator. It is a front partial enlarged view of a cooler and its peripheral part. It is a side surface partial enlarged view of a cooler and its peripheral part. It is a detailed perspective view of a defrost heater. It is a flowchart which shows the flow of control of a defrost operation. It is a figure which shows transition of the detected temperature of the cooler temperature sensor after the start of defrosting when there is much frost formation amount. It is a figure which shows transition of the detection temperature of the cooler temperature sensor after the start of defrosting when there is little frost formation amount. It is a figure which shows the relationship of the defrosting time required for it with respect to the amount of frost formation. It is a figure which shows the 1st modification of the method of attaching a cooler temperature sensor to a cover member. It is a figure which shows the 2nd modification of the method of attaching a cooler temperature sensor to a cover member. It is a figure which shows the 3rd modification of the method of attaching a cooler temperature sensor to a cover member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerator 2 Refrigerated room 3 Ice making room 4 Upper stage freezer room 5 Lower stage freezer room 6 Vegetable room 7 Cooler 7a Cooler piping 7b Fin 8 Cooler storage room 9 Blower (blower)
DESCRIPTION OF SYMBOLS 10 Heat insulation box 11 Refrigerating room air duct 12 Upper stage freezer room air duct 13 Lower stage freezer room air duct 16 Refrigerating room return duct 17 Freezer room return port 20 Refrigerating room damper 22 Defrost heater 22a Heater part 22b Radiation fin 24 Compressor 31 Control Substrate 35 Cooler temperature sensor 37 Defrosting temperature sensor 38, 38A Holder 38a Opening 39 Heat insulation member 41 Mounting member 41a Vertical portion 41b Horizontal portion 44 Recess 45 Notch 50 Freezer damper 53 Upper cover 53a Cover member (temperature detection) Element)
53b End member 53c Reinforcing member

Claims (3)

A refrigerator including a refrigeration cycle in which a compressor, a condenser, a throttle, and a cooler are sequentially connected by a refrigerant pipe, a blower that circulates air cooled by the cooler, and a defrost heater provided below the cooler In
A refrigerator having a defrosting temperature sensor provided between the cooler and the defrosting heater. A cover member is provided to cover the top of the defrost heater,
The refrigerator according to claim 1, wherein the defrosting temperature sensor is attached so as to detect a temperature of the cover member.   The refrigerator according to claim 2, wherein the defrost heater is attached so as to be in thermal contact with the cover member.

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