JPS6363834B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigerator in which frost adhering to an evaporator is defrosted using a defrosting heater.

Generally, after the defrosting heater is used as a control means in such refrigerators, the pressure in the refrigeration system becomes extremely high, so instead of starting the compressor immediately and restarting cooling operation, A time is set for the internal pressure to drop below a predetermined value, and after defrosting is completed, the device is activated after this set time has elapsed.

The above setting time is set to enable the compressor to start in a limited number of areas with poor power supply voltage supply conditions, so it is not possible to start the compressor in areas with normal voltage, which is the majority of the usage frequency. The setting time becomes long, which causes the temperature inside the refrigerator to rise. Also, if you want to shorten the setting time, increase the starting torque of the compressor,
Countermeasures such as increasing the number of starting electrical components were necessary.

The present invention solves the above-mentioned conventional drawbacks and starts the compressor by changing the set time according to the power supply voltage.

An embodiment of the present invention will be described below based on the drawings.

Reference numeral 1 is a pulse source configured to generate pulses, and its output is connected to one input of an AND circuit 2 and the respective clock inputs of compressor start-up wait timers 3 and 4. 5 is a freezer compartment temperature detection circuit of a refrigerator (not shown), which includes a comparator 6;
It consists of resistors R ₁ , R ₂ , R ₃ and thermistor TH ₁ . This temperature detection circuit 5 uses a resistor _R1 and a thermistor for the potential at point B determined by resistors _R2 and _R3 .
When the potential at point A, which changes depending on the temperature of TH ₁ , is high, the output of the comparator 6 is "1", and when it is low, it is "0". The output of this comparator 6 is connected to the input of a logic block 7. Logic block 7 is connected to the input of AND circuit 8. The output of AND circuit 8 is inverter 20
is connected to send a start signal to a compressor (not shown) via the compressor.

9 is a defrosting end temperature detector; comparator 10;
It is constructed in the same way as the freezer room temperature detector 5 with resistors R ₄ , R ₅ , R ₆ and a thermistor TH ₂ installed near the evaporator, and when the potential at point C is higher than the potential at point D, the comparator The output of 10 is “1”,
If it is low, it operates to become "0". The output of comparator 10 is connected to send a reset signal to defrost timer 11 and R-S flip-flop 12. Q of R-S flip-flop 12
The output sends a signal to a defrosting heater (not shown) provided in the evaporator via the inverter 13, and also sends a signal to the R
-S flip-flops 14 and 15 are connected to send a reset signal, and via inverters 21 and 22, the start wait timers 3 and 4 are connected to send a reset signal. The output of the defrosting timer 11 is connected to an RS flip-flop 12, and the output of the startup wait timer 4 is connected to an RS flip-flop 15 so as to send a set signal. The output of the startup wait timer 3 is connected to one input of the AND circuit 16, and the AND circuit 16 performs an AND operation with the output signal of the power supply voltage detector 17 supplied to the compressor.
-S is connected to send a set signal to the flip-flop 14. This power supply voltage detector 17 outputs "1" when the power supply voltage V is above the set value _V1 , and outputs "0" when it is below. R-S flip-flop 1
Each Q output of 4 and 15 is OR circuit 18
The result is ORed and connected to the AND circuit 8 via an inverter 19. The output of the AND circuit 8 is connected to send a start signal to the compressor via the inverter 20 as described above, and is also connected to one input of the AND circuit 2.

Next, the relationship between the set times of the startup wait timers 3 and 4 and the balance pressure within the refrigeration system will be explained with reference to FIG. Here, let P ₁ be the set pressure when the power supply voltage V is at a normal level, that is, the set value V ₁ or more, and P ₂ be the set pressure when the power supply voltage supply situation is bad and the set value V ₁ or less. Since the startup wait time of the former is short, the setting time of startup wait timer 3 is
Since the _latter requires a long activation waiting time, the setting time of the activation waiting timer 4 is t ₂ . In this case, if the power supply voltage V is _V1 or more, the compressor is started with a startup waiting time of _t1 , and if it is _V1 or less, the compressor is started with a startup wait time of _t2 .

Next, the operation of the circuit configured as described above will be explained.

During normal operation, when the temperature inside the freezer is high, the resistance value of the thermistor _TH1 decreases and the A potential becomes higher than the B potential, so the output of the comparator 6 becomes "1". On the other hand, when the temperature is low, it becomes "0", and a signal is sent to start or stop the compressor depending on the temperature inside the freezer. On the other hand, the output of the defrosting end temperature detector 9 is a thermistor because the evaporator temperature is low.
The resistance value of TH ₂ is high, and the C potential becomes lower than the D potential, resulting in a "0" state, which causes the defrost timer 11 to integrate, and a reset signal is sent to the R-S flip-flop 12, so the defrost heater is activated. is not sending an energization signal. The defrost timer 11 integrates the number of pulses sent from the pulse power source 1 in response to the compressor start signal output from the freezer room temperature detector 5, and when this integrated time reaches a set value (e.g. 8 hours), R - Sends a set signal to the S flip-flop 12 and sends an energization signal to the defrosting heater.
At the same time, a reset signal is sent to the R-S flip-flops 14 and 15 to stop the compressor. As defrosting progresses and the evaporator temperature rises to exceed the set temperature, the output of the defrost end temperature detector 9 becomes "1", the defrost timer 11 is reset and integration is restarted, and the R-S flip-flop is activated. 12 and stop supplying electricity to the heater. At the same time, startup wait timers 3 and 4 are reset, and each timer starts integration. When the set time _t1 of the startup wait timer 3 has elapsed, if the power supply voltage V detected by the power supply voltage detector 17 is higher than the set voltage _V1 , a compressor startup signal is issued and the compressor is operated. However, if the set voltage V ₁ is lower than V 1, the startup wait timer 4 continues to integrate, and the set times t ₂ and t ₁
Because the length is longer, the balance pressure P in the system decreases as shown in Figure 2, so a start signal is sent to the set voltage after the set time _t2 regardless of the height of the power supply voltage V, which is low, and compression is easily performed. The machine starts. In this way, the startup waiting time can be selected depending on the power supply voltage.

As is clear from the above explanation, according to the present invention, when starting the compressor after defrosting is completed, the waiting time for starting the compressor can be selected depending on the power supply voltage supply situation, thereby causing unnecessary temperature rise inside the refrigerator. This has many effects, such as preventing this and reducing the starting torque.

[Brief explanation of drawings]

FIG. 1 is a logic circuit diagram of a refrigerator control section showing an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between balance pressure P in the refrigeration system of the refrigerator and startup waiting time t. 3...Start wait timer, 4...Start wait timer, 5...Freezer room temperature detector (temperature detection device),
9... Defrost end temperature detector (defrost end detection device),
11... Defrost timer, 14, 15... R-S flip-flop (means), 17... Detector.

Claims (1)

[Claims] 1. A temperature detection device that detects the temperature inside the refrigerator and controls the compressor, a defrost timer that integrates the operating time of the compressor and issues a defrost signal at a predetermined accumulated time, and a defrost that issues a defrost end signal. an end detection device; a startup wait timer that starts integration in response to a signal from the defrost end detection device and issues a startup signal for the compressor after a predetermined startup wait time; and a detector that detects a supply voltage of the compressor. and means for changing the startup wait time set by the startup wait timer according to the power supply voltage detected by the detector.