JPS6321473A - Defroster for refrigerator - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a defrosting device for a refrigerator that controls the temperature inside a storage chamber by controlling the rotation speed of a compressor in a refrigeration cycle.

(b) Conventional technology Modern refrigerators use compressor rotation speed control, which stabilizes storage room temperature and reduces power consumption due to frequent startup and shutdown, compared to the conventional compressor ON-OFF control system. The method is beginning to be adopted. For example, this is JP-A-60-263
As disclosed in Japanese Patent No. 070, the number of revolutions of the compressor is changed according to the temperature of the storage chamber to quickly respond to temperature fluctuations.

Conventionally, defrosting of a cooler in a refrigeration cycle is based on the assumption that the amount of frost formed with respect to the operation of the compressor per unit time is approximately constant. The device was configured to perform defrosting at a constant rate. This is because defrosting can be performed with a certain amount of frost.

However, as mentioned above, when the rotation speed of the compressor is changed, the speed of frost formation on the cooler also changes, so the amount of frost formed per predetermined operating time of the compressor is not constant, and proper frost formation cannot be achieved. Unable to start defrosting due to volume.

In order to solve this problem, Japanese Patent Application Laid-Open No. 147083/1983 prepares a charge storage element, applies an input proportional to the rotational speed of the compressor to the element, and starts defrosting when a predetermined amount of charge is accumulated. There is.

(c) Problems to be Solved by the Invention In devices using charge storage elements such as those described above, the defrosting start timing can be changed according to the speed of frost formation on the cooler, so defrosting starts with a constant amount of frost formation. However, such a charge storage element is expensive and has the problem of insulation deterioration due to aging, resulting in a defrosting device with low reliability.

(d) Means for Solving the Problems The present invention has been achieved in order to solve these problems, and the present invention will be described in detail below with reference to Examples.

Microcomputer (25) of control electric circuit (24)
) is the operating frequency of the electric compressor (20) (
The temperature (T, ) is controlled by changing the rotation speed). The cooler (10) of the refrigeration cycle is operated by the electric compressor (20).
), which is removed by the heater (42). The microcomputer (25) has a time limit means (50) as its function, and the time limit means (50) consists of an oscillation means (51), a counter (52), and a frequency divider (53), and the time limit means (50) consists of an oscillation means (51), a counter (52), and a frequency divider (53). A defrosting start command (S) is issued upon integration of , and the microcomputer (25) energizes the heater (42).At this time, the microcomputer (25) determines that the operating frequency of the electric compressor (20) is 30Hz. When it is higher, input the foHz pulse of the oscillation means (51) to the counter (52), 30)! Below z (excluding when stopped), f, via the frequency divider (53)
Input a Hz pulse.

(E) Function According to the present invention, the operating period until the counter completes the integration can be changed in accordance with the rotational speed of the electric compressor.

(F) Embodiment An embodiment will be explained with reference to the drawings. FIG. 2 shows a refrigerator-freezer (1) as an example. (2) is an insulated box body, and the inside of the refrigerator is divided into upper and lower sections by an insulating partition wall (3), with a freezer compartment (F) serving as the first compartment at the top and a refrigerating compartment (R) serving as the second compartment at the bottom. ) are partitioned. (
6) and (7) are heat insulating doors that separately open and close the front openings of the freezer compartment (F) and the refrigerator compartment (R). A cooling chamber (8) is formed within the partition wall (3),
A cooler (10) included in the refrigeration cycle can be housed and installed within this. A duct (11) that communicates with the cooling chamber (8) and both chambers (F) and (R) is formed behind the cooler (10), and a blower (
At step 12), the air cooled by the cooler (10), that is, cold air, is sucked in and forcibly blown out into the duct (11). (
12M) is a motor that drives the blower <12). The cold air blown into the duct (11) is blown into the freezing compartment (F) through the discharge port (14) and into the refrigerator compartment (R) through the discharge port (15). (17) is the discharge port (15)
A gas-filled damper thermostat installed in the refrigerator compartment (R) to open and close the discharge port (15) with a baffle plate (18) based on the temperature in the refrigerator compartment (R). ) is controlled, for example, between +7°C and +3°C to an average of +5°C. (19) is the insulation cover of the damper thermostat (17). Also, (20) is the electric compressor installed in the machine room (21) at the bottom of the refrigerator-freezer (1) and included in the refrigeration cycle. Machine room (21)
Inside, a condenser (22), which is also included in the refrigeration cycle, and a blower (23) for cooling the condenser (22) and the electric compressor (20) described above can be installed. Furthermore, (5
〉 is an operation panel attached to the front of the door (6).

FIG. 1 shows the control electrical circuit (24) of the present invention.

(25) is a microcomputer, which includes A/D converters (26), (27) and (28) and a microphone r:y CP
Has U (30) (7) functions. (31) is the freezer compartment (
F) is a sensor that detects the temperature (TF) of A/D
The signal is input to the micro CPU (30) via the converter (26). (32) is a sensor that detects the temperature (T7) of the cooler (10), and its output is similarly input to the micro CPU (30) via the A/D converter (27). (33) is a setting switch for setting the temperature of the freezer compartment (F), which can be input to the micro CPU (30) via the A/D converter (28).
)'s output passes through a D/A converter (36) and an inverter circuit (37) to control the rotational speed of a three-phase synchronous motor (20M>) for driving the electric compressor (2o).
The output of the PU (30) passes through a D/A converter (38) and controls the motor (12M) by a driver circuit (39). Furthermore, the output of the micro CPU (30) can be input to the driver circuit (41) via the D/A converter (40), and this driver circuit (41) controls the defrosting heater (42) of the cooler (10). The heater (42) is provided to be thermally conductive with the cooler (10).

FIG. 3 shows a refrigerant circuit diagram of the refrigeration cycle of the refrigerator-freezer (1). The high-temperature, high-pressure refrigerant discharged from the electric compressor (20) radiates heat in the condenser (22), is decompressed in the pressure reducer (47), and flows into the cooler (10), where it evaporates and releases heat of vaporization. It is taken from the surrounding area and then sucked into the electric compressor (20).

Next, referring to the graph showing the relationship between the operating frequency of the electric compressor (20) and the temperature (1'F) of the freezer compartment (F) in FIG. 4, CPU (3
The operation of 0) will be explained. If the temperature (T, ) of the freezer compartment (F) that can be set with the setting switch (33) is (rs) (here, it can be set from -12°C to -22°C), the operating frequency is normally set as shown by the solid line in the figure. change. That is, the temperature (T, ) sensed by the sensor dimension - (31〉) is currently high < (
TS+4), the inverter circuit sets the operating frequency of the electric compressor (20) to the maximum rotation speed of 120 t. As a result, the temperature (T, ) of the freezer compartment (F) rapidly decreases. As a result, when (TF) reaches (Ts+4), the current state is maintained for, for example, 3 minutes from that point, and then the operating frequency is lowered to 90H2. This slows down the rate of decrease in temperature (TF). When (TF) further reaches (I', +2) from this state, the current state is similarly maintained for 3 minutes from that point, and then the frequency is lowered to 60 Hz. This further slows down the rate of decrease in temperature (TA). After that, when (T, ) is reached, the operating frequency is similarly lowered to 30H2 3 minutes after that point. In this way, the temperature (TF) approaches the set temperature (T, ), and so-called overshoot can be reduced.

Conversely, when the temperature (T,) increases from the operating frequency of 30H2 and reaches (T,), the current state is similarly maintained for 3 minutes from that point, and then the temperature is raised to eonz. Furthermore (Ts
+z), it accelerates to 90H2 3 minutes after reaching (Ts"2). Similarly, it increases to 120Hz 3 minutes after reaching <XS+4). In this way, the micro CPU (30 ) is the temperature (T, ) is (T,
+4), (TS+2>, (T,), a command to change the operating frequency is generated internally, but from that point on, the frequency will not be changed for 3 minutes as described above. The same applies even if the frequency to be changed to Frequent changes in the operating frequency can be prevented, and deterioration of the motor (20M) and expansion of noise can be prevented.

Ideally, the capacity of each device should be set so that the temperature (T,) can be maintained at the set temperature (T, ) by 30H2 operation, but the load in the freezer compartment (F) is small, and the refrigerator-freezer (1) In situations where the ambient temperature is low, the temperature (T, ) decreases even during 30H2 operation. In this case, the motor (20t') is stopped when it reaches (Ti-z>. This prevents overcooling in the freezer compartment (F). Then, the temperature (
When T, ) rises and reaches ('rs-z), it remains stopped for 5 minutes from that point, and then the electric compressor (20)
Start up and set it to 30H2. This prevents deterioration of the electric compressor (20) due to frequent startup and stoppages. As mentioned above, since the operating frequency of the electric compressor (20) is successively changed depending on the difference between the temperature (TF) and the set temperature, the temperature (TF)
) is substantially stably controlled to a set temperature (TS) (for example, -18°C). In addition, the blower (12) is an electric compressor (20
) will continue to operate while it is in operation. Furthermore, the frequency change does not always take place in the steps shown in Figure 4; for example, the temperature (TF) may suddenly rise from the current temperature (T5) due to reasons such as leaving the door (6) open for a long period of time. In this case, the frequency will change to 120H2 3 minutes after the frequency change command is issued inside the micro CPU (30).
Increase the operating frequency towards

Next, the cooler (10) is controlled by the microcomputer (25).
) defrosting control will be explained. Figure 5 shows the timer means (5) that the microcomputer (25) has as its function.
0) is shown. (51) is, for example, the frequency f. This is an oscillation means that outputs an oscillation pulse of Hz, and the oscillation pulse is input to the input terminal (52a) of the counter (52) via an analog switch (SWI). The output of the oscillation means (51) is further input to the frequency divider (53) to set the frequency to foHz, and then the analog switch (S
Wt) to the input terminal (52a) of the counter (52)
is input. The counter (52) is an input terminal (52a)
The oscillation pulses input from the counter (52b) are counted, and the integration is finished at a predetermined integrated value, and a defrosting start command (S>) is generated from the output terminal (52b). ) is used to reset the input streak counter (52) to the reset terminal (52c) of the input terminal (52c).The counter (52) is reset for example 8 hours from the start of integration when pulses of frequency f. are continuously input to the input terminal (52g). The integration shall end at .

Next, the operation will be explained. The microcomputer (25) makes all the analog switches (SW l ) (SW x ) non-conductive while the electric compressor (20) is stopped. Moreover, when the operating frequency of the electric compressor (20) is higher than 30Hz,
That is, during periods of 60 Hz, 90 Hz, and 120 Hz, only the analog switch (SWI> is conductive, and 3
At 0Hz, only the analog switch (SWt) is conductive. Since the counter (52) counts when the oscillation pulses are inputted, the counter (52) performs the counting operation only while the electric compressor (20) is operating. i.e. electric compressor (20)
The driving time will be accumulated. In addition, electric compressor (2
If the operating frequency of 0) is 60Hz, 90) 1z or 120Hz, the analog switch (SWI
) is continuously conducted, so the electric compressor (20)
When the operating time reaches 8 hours, the counter (52) generates the above-mentioned defrosting start command (S). The microcomputer (25) stops the electric compressor (20) when the command (S) is issued, and the driver (41) turns on the heater (
42) Start energizing. As defrosting progresses, the cooler (10
) rises to the predetermined defrosting end temperature, the microcomputer (25)
Upon sensing the deflection, the heater (42) is energized and the electric compressor (20) is again put into an operable state.

On the other hand, when the electric compressor (20) is continuously operated at, for example, 30Hz, only the analog switch (SWt> is turned on, and the counter (52) can input all the 3A foHz oscillation pulses, so the counter (52) It will take 16 hours, twice as long as before, to complete the integration.In other words, at this time, when the electric compressor (20) has been operating for 16 hours, the defrost start command (S) is issued, and the defrost will be started.

Also, the electric compressor (20) was operated continuously for m, but the operating frequency was changed midway through, for example, it was operated at 60 Hz for 3 hours from the start of the integration of the counter (52), and then at 30 Hz for 4 hours.
Hz, and if the operation is continued for 3 hours at 60 Hz, the frequency of the oscillation pulse that can be input to the counter (52) becomes f, as shown in FIG. from Hz to foHz and again f
. As a result, the counter (52) completes the integration after 10 hours.

The frosting speed on the cooler (10) is determined by the electric compressor (20).
It is considered that the rotation speed of the electric compressor (20) is approximately proportional to the cooling capacity of the refrigeration cycle, so when the rotation speed of the electric compressor (20) is high, defrosting starts in a short operating period, and when the rotation speed is low, it starts defrosting for a long period of time. By changing the operating period, it becomes possible to start defrosting the cooler (10) with a substantially constant amount of N, which prevents the temperature inside the refrigerator from rising due to wasteful defrosting, and also prevents abnormalities. It is possible to prevent a decrease in cooling efficiency due to an increase in the amount of frost formed. Moreover, at this time, there is no need for a charge storage element, etc., and this is achieved by the timer (50) as a function of the microcomputer (25), so that the cost can be reduced and a highly reliable defrosting device is constructed. .

(G) Effects of the Invention According to the present invention, in a refrigerator that controls the rotation speed of the compressor to adjust the temperature inside the storage room, the operating period of the compressor until the time when defrosting of the cooler starts is reduced. Since it changes according to the rotation speed, even if the cooling capacity of the refrigeration cycle is variously changed by changing the rotation speed of the compressor, it is possible to defrost the cooler with a constant amount of frost at all times, eliminating unnecessary defrosting. It is possible to prevent a rise in temperature within the storage room due to frost and a decrease in cooling capacity due to abnormal frost formation.

Further, at this time, there is no need for a conventional charge storage element, etc., and the defrosting device can be configured with a timer consisting of an oscillation function and an integration function, and is highly reliable and can be reduced in cost. .

[Brief explanation of the drawing]

Each figure shows an embodiment of the present invention. Figure 1 is a control electric circuit diagram, Figure 2 is a side sectional view of a refrigerator-freezer, Figure 3 is a refrigerant circuit diagram, and Figure 4 is an electric compressor diagram. FIG. 5 is a functional block diagram of the timer as a function of the microcomputer, and FIG. 6 is a diagram showing one form of the integration operation of the timer. (F)... Freezer, (10)... Cooler, (2
0)...Electric compressor, (25)...Microcomputer, (37)...Inverter circuit, (42)...
)... Heater, (50)... Timing means, (51
)...Oscillation means, (52)...Counter, (53
)...Frequency divider. Applicant: Sanyo Electric Co., Ltd. and one other representative Patent attorney Takuji Nishino and one other person Go to Figure 3 and Figure 5 n 2 g S g. ? Riyo Tora exhibition group early figure 6

Claims (1)

[Claims] 1. Adjust the temperature inside the storage chamber by controlling the rotation speed of the compressor of the refrigeration cycle, and defrost the cooler of the refrigeration cycle with a defrost start command by a timer that integrates the operating time of the compressor. In the refrigerator to carry out the frost,
The time limit means has an integration means that performs an integration operation of periodic oscillation output, and generates the defrosting start command at a predetermined integrated value of the integration means, and also outputs the defrosting start command according to the rotation speed of the compressor. A defrosting device for a refrigerator characterized by changing the oscillation cycle of oscillation output.