JPS5910545Y2 - Cooler frost detection device - Google Patents

Description

[Detailed description of the invention] This invention is a frost detection device for a refrigerator that uses a frost detector attached to the cooler of a refrigerator to detect frost adhering to the cooler at a constant amount of frost and issues a defrosting command. It is related to.

Conventionally, a frost detector for detecting frost that has formed on a cooler such as a refrigerator has been installed on the end plate of a forced draft cooler on the ventilation air suction side, where there is generally a lot of frost formation.

However, the way frost forms on the cooler varies greatly depending on environmental conditions and other factors.

In other words, if stored items are frequently put in and taken out of the refrigerator during hot and humid times such as summer, a large amount of frost will form on the intake side of the ventilation air of the cooler, but only a small amount of frost will form on the discharge side. There will be no frost formation.

Furthermore, when there is little movement of stored items in and out during the low temperature and low humidity winter season, a large amount of frost forms on the ventilated air discharge side of the cooler.

Therefore, even if the unit is installed on the ventilation air suction side of the end plate of the cooler, where there is a lot of frost, there is variation in the amount of frost detected throughout the year, and it is not possible to always issue a defrost command at the optimal time. The drawback was that the efficiency of the device decreased.

SUMMARY OF THE INVENTION The object of the present invention is to provide a frost detection device for a cooler that eliminates the above drawbacks.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 denotes a frost detector, which includes a metal casing 2 with good thermal conductivity, a piezoelectric element 4 attached to a vibrating surface 3 integrally formed through an elastic part 2a of this casing 2,
It consists of a self-heater 5 that removes frost that adheres to the vibrating surface during defrosting.

Reference numeral 6 designates a molding material such as epoxy resin for fixing the heater 5, and 7 designates an airtight plate that airtightly separates the vibrating part where the piezoelectric element 4 is located and the molded part of the heater 5 located below.

8 is a lead wire of the heater 5, and 9 is a lead wire of the piezoelectric element 4.

Reference numeral 10 denotes a cooler composed of a large number of cooling fins 11 and cooling pipes 12 orthogonal to the fins, and 13 is a fan motor for forcing air through the cooler 10.

Reference numeral 14 denotes an end plate of the cooler] 0, on which the frost detector 1 is attached to the ventilation air suction side.

Next, the electric circuit will be explained. In FIG. 3, 15 is an oscillation circuit connected to the piezoelectric element 4, which causes the piezoelectric element 4 to oscillate at a certain oscillation level.

A positive characteristic resistance element 16 is connected in parallel with the piezoelectric element 4 and changes its resistance value according to the outside temperature, and changes the oscillation level of the piezoelectric element 4 according to the outside temperature.

17 is a defrosting heater attached to the cooler 10;
A relay R connected in parallel with the heater 5 of the frost detector 1 and activated when the piezoelectric element 4 stops oscillating due to frost formation.
It is connected to a power source via a normally open contact R2 and a thermostat 19 for temperature inside the refrigerator.

Further, the electric compressor 18 of the cooling cycle is connected to a power source via a normally closed contact R1 of a relay R and a thermostat 19 for temperature inside the refrigerator.

When such a device is used in high temperature and high humidity conditions in the summer, a large amount of frost forms on the intake side of the ventilated air of the cooler 10, and a small amount of frost forms on the discharge side. Even if the positive characteristic resistance element 16 detects high-temperature outside air and its resistance value increases, the oscillation level of the piezoelectric element 4 connected in parallel becomes stronger, and the ventilation air suction side in the end plate increases. Unless a large amount of frost forms on the attached frost detector 1, frost detection will not occur.

Conversely, in the case of use in winter at low temperature and low humidity, even if there is a frosting condition in which only a small amount of frost forms on the suction side of the ventilated air of the cooler 10 and a large amount of frost forms on the discharge side, the above-mentioned Positive characteristic resistance element 1
6 detects low-temperature outside air and its resistance value decreases, so the oscillation level of the piezoelectric element 4 connected in parallel becomes weaker and even a small amount of frost on the frost detector 1 can be detected.

Further, FIG. 4 shows a case where electrical connections different from those in FIG. 3 are adopted, and the same parts as in FIG. 3 are represented using the same symbols.

In the figure, 16' is a negative characteristic resistance element whose resistance value changes depending on the outside temperature, and is connected in series with the piezoelectric element 4.

According to the electric circuit shown in Fig. 4, when used in high temperature and high humidity conditions in summer, a large amount of frost forms on the suction side of the ventilated air of the cooler 10, and a small amount of frost forms on the discharge side. Even in a frost state, the negative characteristic resistance element 16' detects high temperature outside air and the resistance value decreases, so that the piezoelectric element 4 connected in series
The oscillation level becomes stronger, and unless a large amount of frost forms on the frost detector 1 attached to the ventilation air suction side within the end plate, frost detection will not occur.

Conversely, in the case of use in winter at low temperature and low humidity, even if there is a frosting condition in which only a small amount of frost forms on the suction side of the ventilated air of the cooler 10 and a large amount of frost forms on the discharge side, the above-mentioned Negative characteristic resistance element 1
6' detects the low-temperature outside air and its resistance value increases, so the oscillation level of the piezoelectric element 4 connected in series becomes weaker and even a small amount of frost on the frost detector 1 can be detected.

Therefore, the amount of frost on the cooler 10 that is detected will always be a constant amount even when the frost state changes between summer and winter.

In addition, similarly to the cooler 10, when the oscillation stops due to frost on the frost detector 1 and is detected, the normally open contact R2 of the relay R, which is the output of the oscillation circuit 15, closes, and the defrosting heater 17 and the frost detector 1 heater 5 is energized and the electric compressor 18
is stopped, and the cooler 10 is defrosted.

When defrosting is completed, the frost detector 1 returns to oscillation, and the relay R is de-energized to restart the cooling operation.

As is clear from the above embodiments, the frost detection device for a cooler of the present invention is provided with a piezoelectric element to form a vibrating surface, and includes a frost detector having a self-heater for defrosting, and a frost detector connected to the piezoelectric element. The piezoelectric element is equipped with an oscillation circuit, and a resistance element whose resistance value changes according to the outside temperature is connected in parallel or in series with the piezoelectric element, so that the outside temperature changes in the summer and winter. Since the strength of the oscillation level is automatically adjusted, for example, the frost formation position will differ depending on high temperature and high humidity such as summer and low temperature and low humidity such as winter, resulting in frost formation on the frost detector. Even if the amount of frost varies, the amount of frost on the cooler is always detected as a constant amount, and a defrosting command can be issued, thereby improving cooling efficiency and saving power.

[Brief explanation of drawings]

Fig. 1 is a plan view of a cooler equipped with a frost detection device according to an embodiment of the present invention, Fig. 2 is a sectional view of a frost detector of the frost detection device, and Fig. 3 is a schematic electrical circuit diagram of the device. , FIG. 4 is a schematic electrical circuit diagram of the above device with an alternative connection. 1...Frost detector, 4...Piezoelectric element, 1
5...Oscillation circuit, 16...Positive characteristic resistance element, 16'...Negative characteristic resistance element.

Claims (1)

[Scope of utility model registration request] A resistive element that is provided with a piezoelectric element to form a vibrating surface, is equipped with a frost detector having a heater for defrosting, and an oscillation circuit connected to the piezoelectric element, and whose resistance value changes according to outside temperature. A frost detection device for a cooler, which is connected in parallel or in series with the piezoelectric element.