JPH0451748B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a frost detection device for a refrigerator, and in particular, it is capable of starting the removal of frost on a cooler of a refrigerator at an optimal time, and reducing the power consumption related to defrosting. Aiming to reduce
This invention relates to a frost detection device for a refrigerator.

[Prior art]

When you operate a refrigerator (refrigerator-freezer, refrigerator, and freezer are collectively referred to as a refrigerator), the air inside the refrigerator is replaced by opening and closing the door and air entering and exiting through the small gap between the door gasket and the main unit.
Moisture in the air forms frost on the cooler, gradually reducing cooling performance. For this reason, once a certain amount of frost has formed, it is necessary to remove it. If defrosting is started too late, too much frost will form, leading to a decline in cooling performance, and the defrosting time will take too long, causing the temperature inside the refrigerator to rise, which will impede food preservation. Come. Furthermore, defrosting more frequently than necessary increases power consumption. Therefore, in order to maintain high cooling performance and operate economically,
It is necessary to start defrosting at the optimal time.

Conventionally, a simple method for determining when to start defrosting the frost that has adhered to the cooler is to use a timer to total the operating time of the compressor, and to start defrosting when this cumulative value reaches a certain set value. An integrated timer method is generally adopted.

However, this integration timer method had the following drawbacks.

(1) This integral timer type refrigerator has a cooler that ensures reliable cooling performance even under extremely severe operating conditions that rarely occur under normal operating conditions. The drawback was that defrosting was performed uniformly twice a day at an ambient temperature of 30°C and once a day at an ambient temperature of 15°C, almost regardless of the amount of frost formed.

(2) In particular, defrosting using this integral timer method has problems in defrosting at low temperatures. This will be explained using FIG. 1.

FIG. 1 is a chart showing how the amount of frost formed on a cooler changes over time in a power consumption test stipulated by JIS. In FIG. 1, the vertical axis represents the amount of frost formation, and the horizontal axis represents the elapsed time. Further, D indicates a time range in which the door is opened and closed a specified number of times, and J indicates a time period during which frost adhering to the cooler is heated by a defrosting heater to defrost. Also, ○

Claims (1)

[Claims] 1. Frost formation on the cooler in a refrigerator in which the air cooled by the cooler is circulated by a blower driven by a fan motor to cool the inside of the refrigerator. A defrosting circuit equipped with a defrosting heater is operated based on the detected value of the amount of frost formation at which the cooling performance of the cooler begins to deteriorate, and the frost is removed by heating by the defrosting heater. In the frost detection device for a refrigerator, a temperature detection element and a wind speed detection element are installed in an air path that leads to a cooler and where air flow resistance increases and wind speed tends to decrease as the cooler becomes frosted. a temperature detection circuit that detects the temperature of the air in the air passage with a temperature detection element; and a temperature detection circuit that is activated after the temperature detected by the temperature detection circuit drops to a reference temperature level, a frost detection circuit that detects the amount of frost on the cooler by detecting the wind speed with a wind speed detection element; A frost detection device for a refrigerator, comprising a drive circuit configured to operate a frost circuit. 2. A current detection device for detecting the current of the fan motor is connected to the frost detection device, and the frost detection device is activated only when a current detection signal indicating that the fan motor has started is received from the current detection device. A frost detection device for a refrigerator according to claim 1, characterized in that: 3. The temperature detection circuit includes a temperature detection section that outputs an electric signal whose magnitude changes proportionally depending on the temperature;
A first reference electrical signal generating section outputs an electrical signal with a magnitude corresponding to the reference temperature level; and a second reference electrical signal generation section that outputs an electrical signal of a magnitude corresponding to the reference wind speed level, and the electrical signal from the temperature detection section of the temperature detection circuit and the first reference electrical signal generation section. and a temperature comparator capable of outputting a matching signal when the two electrical signals match, and activating the frost detection circuit based on the matching signal, the frost detection circuit Comparing the electrical signal from the wind speed detection section and the electrical signal from the second reference electrical signal generation section, outputting a matching signal when both electrical signals match, and activating the drive circuit by this matching signal. The frost detection device for a refrigerator according to claim 1, further comprising a wind speed comparator capable of detecting a wind speed. 4 By integrating the temperature detection circuit and the frost detection circuit,
It is characterized by a temperature/frost detection circuit that can detect temperature and wind speed with the same temperature/wind speed detection element, and a voltage switching circuit that switches the voltage level applied to the temperature/frost detection circuit into two high and low levels. A frost detection device for a refrigerator according to claim 1. 5. Claim 3, characterized in that the second reference electric signal generation section of the frost detection circuit uses a reference wind speed element having the same temperature characteristics as the wind speed detection element used in the wind speed detection section. Refrigerator frost detection device as described. 6 The temperature/frost detection circuit includes a temperature/wind speed detection section that outputs an electrical signal whose magnitude changes proportionally depending on the temperature and wind speed, and a second section that outputs an electrical signal whose magnitude corresponds to the reference temperature level. a reference electrical signal generator, which compares the temperature-related electrical signal from the temperature/wind speed detector with the electrical signal from the first reference electrical signal generator, and generates a matching signal when both electrical signals match. A temperature comparator is provided which can output a matching signal and activate a voltage switching circuit in response to the coincidence signal to apply a high voltage to the temperature/frost detection circuit, The electrical signal is compared with the electrical signal from the second reference electrical signal generator, and when the two electrical signals match, a matching signal is output, and the driving circuit can be activated by this matching signal. The frost detection device for a refrigerator according to claim 4, further comprising a wind speed comparator. 7. A patent characterized in that a flip-flop is provided between the wind speed comparator and the drive circuit, which is activated by a coincidence signal from the wind speed comparator and stopped by a defrost end signal from the defrosting circuit. A frost detection device for a refrigerator according to claim 3 or 5. 8. A patent characterized in that a flip-flop is provided between the wind speed comparator and the drive circuit, which is activated by a coincidence signal from the wind speed comparator and stopped by a defrosting end signal from the defrosting circuit. A frost detection device for a refrigerator according to claim 4 or 6. 9. The frost detection device for a refrigerator according to claim 4 or 8, characterized in that a delay circuit is provided between the second reference electric signal generating section and the voltage switching circuit.