JPH02161281A - Refrigerator - Google Patents

Abstract

PURPOSE:To efficiently remove remaining liquid refrigerant in an accumulator during defrosting and defrost the periphery of the accumulator and to defrost without remaining ice by providing defrosting time operating means for temporarily operating a compressor during the defrosting. CONSTITUTION:When a time t1 is elapsed after defrosting is started, a compressor is operated for a time t2. At the time point immediately before the start of this operation the pressures at the discharge port and suction port sides of the compressor are substantially balanced at approx. 2kg/cm<2>(gauge pressure). When the compressor is operated in this state for the t2 (e.g., 20 - 30sec), remaining liquid refrigerant in an accumulator 3 is sucked to the suction port side of the compressor, and the remaining liquid refrigerant is substantially removed from the accumulator 3. In this case, the remaining liquid refrigerant in a condenser flows into a cooler 1, but since the cooler 1 is subsequently heated by a defrosting heater 4 so that a large thermal load is applied. The introduced liquid refrigerant is evaporated in the sections of the cooler 1 so as not to arrive at the accumulator 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Statement of the Invention] (Industrial Application Field) The present invention relates to a refrigerator that determines when to end a defrosting operation based on a temperature detected by a defrosting temperature sensor.

(Prior art) Conventionally, this type of refrigerator has been equipped with a defrost heater near the cooler, and a defrost temperature sensor installed in the accumulator located on the refrigerant outlet side of the cooler, which is the part where defrosting takes the longest. At the time of installation and defrosting operation, defrosting is terminated when the detected temperature of this defrosting temperature sensor rises to a set temperature. The reason why the defrosting of the area around the accumulator is delayed the most is that liquid refrigerant remains in the accumulator, and the residual liquid refrigerant evaporates during defrosting to continue cooling the area around the accumulator.

(Problem to be Solved by the Invention) By the way, during the defrosting operation, the defrosting heater continues heating, so as the defrosting time elapses, the ambient temperature around the cooler and eventually the ambient temperature around the defrosting temperature sensor gradually decreases. In particular, if there is a large amount of residual refrigerant in the accumulator, the temperature detected by the defrosting temperature sensor may exceed the set temperature due to the surrounding atmospheric temperature before the area around the accumulator is sufficiently defrosted. There were times when I exceeded it.

In this case, defrosting ends with residual water remaining around the accumulator, causing residual ice.

The present invention has been made in consideration of these circumstances, and an object thereof is to provide a refrigerator that can efficiently defrost the area around the cooler and accumulator and eliminate residual ice.

[Structure of the Invention] (Means for Solving the Problems) The refrigerator of the present invention includes a cooler that cools the inside of the refrigerator by receiving refrigerant supplied from a compressor, a defrosting heater that defrosts the cooler, and a defrosting heater that defrosts the cooler. and a defrosting temperature sensor that detects an external ambient temperature of an accumulator located on the refrigerant outlet side of the cooler, and the end timing of the defrosting operation by the defrosting heater is determined based on the temperature detected by the defrosting temperature sensor. The defrosting operating means for temporarily operating the compressor during the defrosting operation is provided.

(Function) Defrosting is performed by causing a defrosting heater to generate heat after the compressor has stopped, thereby melting and removing the Japanese water that has accumulated around the cooler and accumulator. During this defrosting operation,
The compressor is operated temporarily, thereby drawing refrigerant into the residual B in the accumulator toward the compressor, and substantially removing the residual liquid refrigerant from within the accumulator. Therefore, defrosting of the area around the accumulator, where defrosting has conventionally been delayed, is performed efficiently, and defrosting is performed without residual ice.

(Example) Hereinafter, one example of the present invention will be described based on the drawings. First, in FIG. 2, reference numeral 1 denotes a cooler installed at the back of a freezer compartment (not shown), and its refrigerant inlet la side is connected to a compressor 2 (first On the other hand, the refrigerant outlet lb side communicates with the suction port of the compressor 2 via the accumulator 3. A defrosting heater 4 made of, for example, a glass tube heater is disposed near the bottom of the cooler 1. Further, a defrosting temperature sensor 5 is attached to the accumulator 3.

On the other hand, in Fig. 1 showing the (& configuration) of the operation control circuit, 6
is a temperature sensor for the freezer compartment provided to detect the temperature inside the freezer compartment (not shown), and this temperature sensor for the freezer compartment 6
The defrosting temperature sensor 5 and the defrosting temperature sensor 5 are composed of, for example, a thermistor having negative resistance temperature characteristics. 7 is a voltage dividing circuit that generates a reference voltage vl corresponding to the set temperature of the freezer compartment; 8 is a comparator that compares the detected temperature signal V" outputted from the freezer compartment temperature sensor 6 with the reference voltage vl; Vj >Vl, a high level signal (cooling operation No. 1) is output.The output signal of this comparator 8 is given to one input terminal of an OR circuit 9, and the output signal of this OR circuit 9 is It is applied to the base of the transistor 10. When the transistor 10 is turned on, the relay drive coil 11 is energized and the relay contact 11a is turned on, thereby starting the compressor 2.

On the other hand, 12 is a voltage dividing circuit that generates a reference voltage (2) corresponding to the set temperature at the end of the defrosting operation, and 13 is a voltage dividing circuit that generates the detected temperature signal Vt output from the defrosting temperature sensor 5 to the reference 7u voltage (2).
A comparator for detecting the end of defrosting compared with 2, Vt
>High level signal (defrosting end signal) when it reaches V2
Output.

On the other hand, 14 is a timer counter for accumulating the operating time of the compressor 2, and its clock terminal CK
The output terminal of the AND circuit 15 is connected to. The output signal (cooling operation signal) of the comparator 8 and the output signal (clock signal) of the clock signal generation circuit 16 are input to both input terminals of this AND circuit 15, so that the AND circuit 15 simultaneously starts operating the compressor 2. circuit 15
A clock signal is output from the timer/counter 14, and the timer/counter 14 starts timing operation. When the time integrated value of this timer counter 14 reaches a set value (for example, 8 hours), a high level signal (defrosting start signal) Va is output from the output terminal Q of this timer counter 14, and the high level signal V +1 is two transistors 17.1
Given to the base of 8. When one transistor 17 is turned on, the relay drive coil 19 is turned on and the relay contact 19a is turned on, thereby energizing the defrosting heater 4 and starting defrosting.

Further, the collector of the other transistor 18 is connected to the output signal line 6a of the temperature sensor 6 for the freezer compartment, and when the transistor 18 is turned on, the collector of the transistor 18 for the freezer compartment 6 is connected to the output signal line 6a.
The output voltage (sensed temperature signal Vr) is forcibly lowered to zero level, the output of comparator 8 is forcibly lowered to low level, and the compressor 2 is operated at fA II-.

Note that the output signal of the comparator 13 for detecting the end of defrosting is given to the reset terminal R of the timer counter 14, and when the output signal is inverted to high level (when the end of defrosting is detected), the timer counter 14 integrated values are reset.

20 is a defrosting operation circuit which is a defrosting operation means for temporarily operating the compressor 2 during the defrosting operation;
This configuration will be explained below.

21 is a total of 1 (:t
in order to【! This is a timer counter for timekeeping, and its clock terminal CK is connected to the output terminal of a three-manufactured AND circuit 22. The three input terminals of this AND circuit 22 are supplied with defrosting start signals V+1, . A clock signal from the clock signal generation circuit 16 and an output signal Vc from an inverter circuit 23 (described later) (a high level signal at the start of defrosting) are input, so that the AND circuit 22 is activated at the same time as the start of defrosting.
A clock signal is output from the timer/counter 21, and the timer/counter 21 starts its time counting operation. When the time integrated value of the timer counter 21 reaches tl, a high level signal (operation start signal) Vb is output from the output terminal Q of the timer counter 21, and the high level signal ? No.v
b is applied to the - input terminal of the AND circuit 24.

The output signal Vc of the inverter circuit 23 (high level signal at time tl) is applied to the other input terminal of the AND circuit 24. Therefore, after t1 has elapsed after the start of defrosting, the output V+1 of the AND circuit 24 is inverted to a high level, and the high level signal Vd is inputted to the OR circuit 9 as an operation start signal, thereby increasing the output of the OR circuit 9. The configuration is such that the level is reversed to high and the operation of the compressor 2 is started. In addition, the reset terminal R of the timer counter 21
is given the output signal of the comparator 13 for detecting the end of defrosting, and when the output signal is inverted to high level (
When the end of defrosting is detected), the integrated value of the timer counter 21 is reset.

On the other hand, 25 is the operating time 1 of the compressor 2 during defrosting operation.
t for timing 1 (e.g. 20 to 30 seconds)
This is a timer counter for two clocks, and its clock terminal CK is connected to the output terminal of a three-person type AND circuit 26. The three input terminals of this AND circuit 26 have t1
Operation start signal vb from timer counter 21 for time measurement,
The clock signal from the clock signal generation circuit 16 and the output signal Vc from the inverter circuit 23 (a high level signal when the compressor 2 starts operating) are input, so that the clock signal is output from the AND circuit 26 at the same time as the compressor 2 starts operating. The signal is output and timer counter 2
5 starts the timing operation. When the time integrated value of the timer counter 25 reaches tl, a high level signal (operation stop signal) Vc is output from the output terminal Q of the timer counter 25, and the high level signal vc is passed through the inverter circuit 23 to a low level. Level signal Ve
The signal is inverted and applied to one input terminal of the AND circuit 24. Therefore, the output Vd of the AND circuit 24 is inverted to low level, and the low level signal Vd is inputted to the OR circuit 9 as an operation stop signal.
The output of the compressor 2 is reversed to a low level, and the operation of the compressor 2 is stopped. Furthermore, timer counter 2
The output signal of the comparator 13 for detecting the end of defrosting is given to the reset terminal -J'H of 5, and when the output signal is inverted to high level (when the end of defrosting is detected)
Then, the integrated value of the timer counter 25 is reset.

Although not shown in the figure, this embodiment has a configuration in which the cold air in the freezer compartment is cooled by circulating it by a fan, and the operation of this fan is prohibited during defrosting operation (No. 4). (see figure). Incidentally, FIG. 3 is a voltage waveform diagram of the main parts in the circuit.

Next, the operation of the above configuration will be explained. During cooling operation, the operating time of the compressor 2 is accumulated by the timer counter 14, and when the accumulated value reaches a predetermined value,
A high-level defrosting start signal Va is output from the output terminal Q of the timer counter 14, thereby turning on both transistors 17 and 18. When one transistor 17 is turned on, the relay drive coil 19 is energized and the relay contact 19a is turned on, thereby energizing the defrosting heater 4 and starting defrosting. At this time, by turning on the other transistor 18, the output voltage of the freezer compartment temperature sensor 6 (detected temperature signal ■r) is forcibly lowered to zero level, and the output of the J comparator 8 is forcibly lowered to the low level. , operation of the compressor 2 is prohibited.

At the same time as the start of such defrosting operation, the above-mentioned defrosting starts/J No. V
a is also applied to the AND circuit 22, and as a result, a clock signal is output from the AND circuit 22 at the same time as defrosting starts, and the timer counter 21 starts timing operation. Then, when the time integrated value of the timer counter 21 reaches ti, a high level signal (operation start signal) vb is output from the output terminal Q of the timer counter 21, and the high level signal vb is sent to the AND circuit 24. given to one input terminal. Therefore, the output Vd of the AND circuit 24 is inverted to a high level, and the high level signal Vd is inputted to the OR circuit 9 as an operation start signal, whereby the output of the OR circuit 9 is inverted to a high level. Along with this, the transistor 10 is turned on, the relay drive coil 11 is energized, the relay contact 11a is turned on, and the compressor 2 starts operating. At this time, power supply to the defrosting tank 4 is continued.

Simultaneously with the start of operation of the compressor 2, the above operation start rf+LVb is also applied to the AND circuit 26, and as a result, a clock signal is output from the AND circuit 26 at the same time as the start of operation 1511, and the timer counter 25 starts timing operation. . When the time product 37rfi of the timer counter 25 reaches tz, a high level No. 13 (operation stop signal) Ve is output from the output terminal Q of the timer counter 25, and the high level signal ve is sent to the inverter circuit. The low level signal V (inverted to 3 and applied to one input terminal of the AND circuit 24 via 23).

Therefore, the output Vd of the AND circuit 24 is inverted to low level, and the low level signal Vd is inputted to the OR circuit 9 as an operation stop signal, thereby inverting the output of the OR circuit 9 to low level, and the transistor lO is turned off and the operation of the compressor 2 is stopped.

In this way, after the start of defrosting, tl (for example, 5 minutes to 1
0 minutes)! l! At that point, turn compressor 2 on to ttcIA.
For example, the compressor 2 is operated for 20 to 30 seconds), but at the time just before the start of operation, that is, about 5 to 10 minutes after the start of defrosting, the pressure on the discharge port side and the suction port side of the compressor 2 decreases. is in a nearly balanced state at approximately 2 kg/cj (cage pressure). In this state, when the compressor 2 is operated for tz (for example, 20 to 30 seconds), the residual fk refrigerant in the accumulator 3 is sucked into the suction port side of the compressor 2, and almost all the residual liquid refrigerant is removed from the accumulator 3. removed. At this time, the residual liquid refrigerant in the condenser flows into the cooler 1, but since this cooler 1 is continuously heated by the defrosting heater 4 and a large thermal load is applied, the inflow liquid refrigerant flows into the cooler 1. It evaporates in various parts and does not reach the inside of the accumulator 3. Therefore, after the compressor 2 is operated, the accumulator 3
Almost no liquid refrigerant remains in the tank.

After the compressor 2 is stopped, only the defrosting heater 4 is energized to continue the defrosting operation. In this case, most of the residual liquid refrigerant in the accumulator has been removed, so
The inconvenience that the area around the accumulator 3 is cooled by the residual liquid refrigerant is eliminated, and defrosting of the area around the accumulator 3, which conventionally tends to be delayed, is efficiently performed.

After that, as defrosting progresses, the accumulator 3
As the outside ambient temperature rises, the resistance value of the defrosting temperature sensor 5 decreases and the detected temperature rises), and the temperature detection t increases accordingly.
The voltage level of No. a Vt increases. When the defrosting of cooler 1 and accumulator 3 is completed,
The temperature detection signal RCT becomes higher than the base N/I voltage v2 of the voltage dividing circuit 12, and the output of the comparator 13 changes to a high-level defrosting end signal, and the defrosting end signal becomes 3.
It is applied to each reset terminal R of the timer counters 14, 21, and 25, and inverts the output of each timer counter 15, 21.25 to a low level. As a result, the transistor 17 is turned off, the defrosting unit 4 is cut off, and defrosting is completed, and the transistor 18 is also turned off, so that the temperature detection signal V' of the freezer compartment temperature sensor 6 returns to the normal state. Thereafter, the operation and stop of the compressor 2 is controlled based on this temperature detection signal V'', and the inside of the freezing chamber is cooled to the set temperature.

In this case, by temporarily operating the compressor 2 during the defrosting operation, most of the residual liquid refrigerant in the accumulator 3 can be removed, so the area around the accumulator 3 is cooled by the residual liquid refrigerant. This problem can be solved, and the area around the accumulator 3, where defrosting has traditionally been delayed, can be efficiently defrosted, and ice can be removed (defrosted).

In the above embodiment, the compressor 2 starts operating 5 to 10 minutes after the start of defrosting, but the start time may be set to 5 minutes or less or 10 minutes or more depending on the model. The operating time is also 20 seconds or more as in the above example.
The time is not limited to 30 seconds, and may be 20 seconds or less or 30 seconds or more.

〔Effect of the invention〕

As is clear from the above description, the present invention is provided with a defrosting operation means for temporarily operating the compressor during defrosting operation, so that almost all the residual liquid refrigerant in the accumulator can be removed during defrosting operation. This eliminates the inconvenience of having the sides of the accumulator cooled by the residual liquid refrigerant, making it possible to efficiently defrost the area around the accumulator, resulting in an excellent effect of being able to defrost without remaining ice. play.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an electric circuit diagram showing an operation control circuit, FIG. 2 is a front view showing the arrangement relationship of a cooler 6, a defrosting heater, and an accumulator, and FIG.
The figure is a 7[i positive waveform diagram of the main part of the operation control circuit, and FIG. 4 is a time chart showing the operating status of the compressor 5 fan and the defrosting heater. In the drawing, 1 is a cooler, 2 is a compressor, 3 is an accumulator, 4 is a defrosting heater, 5 is a defrosting temperature sensor, 6
is for the freezer/! ! temperature sensor, 14 is a timer counter for accumulating compressor operating time, 16 is a clock signal generation circuit, 20 is a defrosting operation circuit (defrosting operation means), 21 is a timer counter for t1 timing, 25 is for t2 timing is a timer counter. Figure 4

Claims (1)

[Claims] 1. A cooler that receives refrigerant from the compressor to cool the inside of the refrigerator, a defrost heater that defrosts the cooler, and a defrost heater that detects the outside ambient temperature of the accumulator located on the refrigerant outlet side of the cooler. a defrosting temperature sensor, and determining when to end the defrosting operation by the defrosting heater based on the temperature detected by the defrosting temperature sensor, wherein the compressor is temporarily turned off during the defrosting operation. A refrigerator characterized in that it is provided with a means for operating during defrosting.