JPS60155876A - Refrigerator frost detection device - Google Patents

Abstract

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

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 attached to a refrigerator cooler (starting at the optimum time for defrosting and reducing the power consumption related to defrosting). This relates to a frost detection device for refrigerators, which is designed to reduce frost.

[Background of the Invention l Refrigerator (refrigerator-freezer, refrigerator, and freezer are collectively called a refrigerator)'lf: When the refrigerator is operated, the inside of the refrigerator is affected by the opening and closing of the door and the entry and exit of air through the slight gap between the door seal and the main body. The air is replaced, moisture in the air forms frost on the cooler, and cooling performance gradually decreases. For this reason, once a certain amount of boxes are attached, it is necessary to remove them. If defrosting is started too late, the amount of layered boxes will become too large, resulting in a decline in cooling performance, and the removal time will take too long, causing the temperature inside the refrigerator to rise, which will hinder the preservation of food. Freshly made. Also, if you perform filial piety more often than necessary, your consuming gun will extinguish. Therefore, maintaining high cooling performance,
In order to operate economically, it is necessary to start removing the vehicle at an optimal time.

Conventionally, a simple method for determining the time M when defrosting is started for the shaft attached to the cooler is to integrate the operating time of the compressor θ) using a timer, and to start defrosting when this integrated value reaches a certain set value. A one-timer type is generally used.

However, this integration timer one-type system does not judge the N* amount.
Since the defrosting schedule is set mechanically, there is a drawback that detailed defrosting control such as adjusting the defrosting timing depending on the amount of frost and adjusting the 1111i during defrosting is not possible. A method of directly or indirectly detecting frost on the cooler by wind speed, wind speed, detection using a piezoelectric element, etc., and starting defrosting when the amount of frost reaches a certain specified value. Attempts have been made, but none of them have been put to practical use because the amount of frost cannot be quantitatively calculated.

[Purpose of the invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and
To provide a frost detection device for a cold paper storage, which defrosts lfa'l deposited on a cooler reliably and at an optimal time, and eliminates waste of power consumption related to defrosting.

[Summary of the Invention] Unlike conventional methods, the refrigerator frost detection device according to the present invention starts defrosting by detecting the formation of a box by utilizing the radio wave absorption property of the sheath.

Generally, water, which is a dielectric substance, has a dielectric loss inherent to water, so when radio waves are emitted to water, the water absorbs radio waves corresponding to the amount of water.

The same is true for ridges, and the amount of absorption of waves θ) and σ) changes depending on the amount of adhesion on the box, so it is possible to some extent to predict the amount of N glue from the absorption of radio waves.

In order to actually determine the radio wave absorption potential of a box, a high frequency signal radio wave is emitted from a high frequency oscillator to the frost via a transmitting antenna, and the remaining radio waves (σ) after this transmitted radio wave is absorbed by the box are sent through the frost. This can be measured by receiving the radio waves with a receiving antenna placed on the opposite side of the body, and this radio wave for transmission and reception utilizes frequency resonance produced by the transmitting antenna and the receiving antenna. namely, a transmitting antenna, and 3.

Frost formation and the amount of frost formation can be measured by detecting the edge of a specific frequency obtained by frequency resonance generated between the receiving antennas and using the fact that the detection edge changes depending on the amount of frost formation.

A concrete means of detecting frost on a refrigerator based on this principle is to arrange transmitting and receiving antennas in the front and rear directions of the air passage of the cooler to enable the transmission and reception of radio waves, and to install heat dissipation fins that form this air passage. -15°C generated on the surface of
Frost formation can be detected from the change in the amount of radio wave absorption caused by the occurrence of a box at around -20'C.

Example of invention C] The present invention will be explained below with reference to embodiments.

Figure 1 is a cross-sectional view of a typical refrigerator-freezer.

The present invention will be explained in detail with reference to this figure. In Figure 1, 1 is the box body of the refrigerator-freezer, 2 is the freezer compartment 3 and the refrigerator compartment 4.
Partition plate to separate the 5-wave refrigerant, pressure i to compress the refrigerant
In machine a, 6 is a condenser, 7 is a cooler for evaporating liquid refrigerant to cool the air inside the refrigerator, and 8 is cooled by this cooler 7. 4.

A blower blows out air to the freezer compartment 3; 9 is an air path for sending air from the freezer compartment 3 to the refrigerator compartment 4; 10 is an air path for sending air that has lost cooling capacity due to leakage heat from the freezer compartment 6 to a cooler 7; 11 is a damper for detecting the temperature Z of the refrigerator compartment 4 and adjusting the air volume to the refrigerator compartment 4; 12 is a refrigerator for returning air from the refrigerator compartment 4 to the cooler 7; This is the room return ventilation path.

In the refrigerator-freezer having this configuration, the wind speed and temperature of the air flowing inside the refrigerator are affected by the amount of frost formed on the cooler 7. In particular, in the case of a refrigerator-freezer θ), cold air blown out by the cooler 7 or the blower 8 circulates within the freezer compartment 3 and returns to the cooler 7 through the freezer compartment return air passage 10. There are two types of air passages: a refrigerator compartment air passage in which cold air blown from the freezer compartment 3 via the air passage 9 circulates inside the refrigerator compartment 4 and returns to the cooler 7; The absolute humidity of the refrigerator room is about 6°C compared to the freezer room temperature of about -18°C.
''C, the temperature is higher in the refrigerator compartment system air passage in the saturated state.Therefore, the box attached to the cooler 7 is the cooler heat radiation near the exit of the refrigerator compartment return ventilation passage 12 returning from the refrigerator compartment 4. There is a lot of frost on the fins (not shown).As this frost increases, the air flow is obstructed and the refrigerator compartment return ventilation path 12
If the wind speed inside the refrigerator room is significantly reduced,
2. The temperature of the air that accumulates inside the chamber increases. The main purpose of the present invention is to detect this attachment to the fin.

Fig. 2 is a schematic structural diagram of a cooler for explaining the present invention. The cooler unit consists of a thin aluminum body and thin plate-shaped aluminum heat dissipation fins. 11
In FIG. 2, 16 is a pipe on the suction pipe side through which the pressure machine sucks refrigerant. 14 is a refrigerant σ) discharge pipe. 15 is a header for preventing refrigerant liquid return. 16 is a support plate for fixing and supporting the distribution system. 17 is a defrosting heater. 18 is a heat radiation fin. Arrows inside the pipes indicate the flow of refrigerant. The air passage to be cooled here flows from the arrow to the arrow A'' and is cooled in this passage.

This cooling] Moisture caught in the wind condenses on the surface of the radiating fins with a pitch of about 5 to 20 degrees and on the surface of the piping, forming minute water droplets, which freeze and form frost, and then grow into [7]. This fills the gaps between the heat dissipation fins, resulting in a decrease in ventilation volume. The range 19 indicated by the dashed line is a region where the reservoir is likely to rise.

4 is a sectional view of the freezing/refrigerating side of the present invention.

The basic form is the same as the refrigerator-freezer shown in Figure 3-1, and the metal outer box 20 has a through hole 21. It is fixed to the hard urethane foam layer 23 in a molded manner. The through hole 21 is closed so that the outer box 20 and the monoball antenna 22 are electrically insulated. One end of the 1,000-nopole antenna 22 is connected to an external signal system via a lead wire 24. A signal radio wave is sent to this dipole antenna 22 from a sweep oscillator (not shown)? It is used as a sending and transmitting antenna. The plastic inner box 25 on the front side of the dipole antenna 22 transmits radio waves, so the radio waves go straight, pass through the surface of the radiation fins, and are absorbed by the attractive surface t'17.
After that, it is received by the receiving dipole antenna 2B.

One end of the receiving dipole antenna 26 is also extended, passes through the through hole 27, and reaches the lead wire 28. The signal from the lead wire 28 is sent to a signal processing circuit such as a detector amplifier and converted into a control signal as will be described later. In the figure, 2
9 is a blower (8σ) motor, 3o is a rear partition plate constituting the refrigerator ¥3, and 31 is a door.

FIG. 174 is an enlarged schematic diagram and a block diagram of main parts for explaining the principle of the present invention. , 114 In the figure, the radiation fin 18 has a pipe 32 for a refrigerant passage that passes through this, and the air passage is parallel to the radiation fin 18, that is, it has a structure that blows through the surface of the radiation fin 18 from the front in the figure.
This constitutes a cooler unit. During operation of this cooler, frost 33 forms in the area shown. Here, the signal radio waves for detecting frost formation are 4 times smoke '2! The ignition output is adjusted to the maximum by the impedance combiner 35, and is passed through the lead wire 36 and terminal 37 from the dipole type transmitting antenna 22 to the inner box 25 of the plastin 8. 68 and travels in the direction of the arrow. A dipole receiving antenna 26 is located on the opposite side of the transmitting antenna 22 and the radiation fin cavity 68, and is attached to a support plate 39 that supports the dipole receiving antenna 26. This support plate 39 may be either a plastic plate or a metal plate, but in the case of a metal plate, a gap 40 is provided for electrical insulation. Reception 4 received by the reception antenna 26
The numbers are terminal 41, lead wire 42, impedance matching device 4
6, the wave is detected by a detector 44, amplified by an amplifier 45, and further sent to a control circuit 46, which is driven to command frost detection and defrost, and to operate a defrost heater.

Next, explain the frost detection mechanism.

Figure 5 is a characteristic diagram showing the detected output of the received signals when there is no frost formation. For example, in Figure +174, the detected output voltage of received receiver No. 4 (assumed to be the output 'voltage of amplifier 45) is
It is shown as a large number of peak waveforms like 7a to 47f. This peak waveform is caused by the fact that when radio waves are transmitted and received between the transmitting antenna and the receiving antenna, frequency resonance occurs between both antennas, resulting in the existence of many resonant frequencies, and each of them has a low frequency detection output. This is something you should check as a peak waveform.

σ) The peak waveform has a frequency of 200 to 2,000 Ml-
(Many of them show a single peak in z, and the output level can be increased by 7 by adjusting the impedance of the signal path. Some of these many peak waveforms are absorbed by the presence of frost and the level θ) decreases. There are antennas that connect directly to each other and do not cause any level changes, so these are used separately for preliminary KA measurements to measure peak waveforms that cause level changes due to frost formation.

Fig. 6 is a graph showing the change in the average value of the detected output voltage due to frost formation. In the figure, the signal 48 is the point at which the detected output voltage is V.σ) at time t, N boxes ago. P.K.
Yes, this is the time when frost formed on the cooler.1. In ■. moves to Vl, and Po moves to PI. Similarly, when the frost builds up, the detection output at time t2 is V,
to v2, Pl transitions to P. When defrosting is performed here, parts of the box change to water droplets, so V2 temporarily transitions to V, and P2 also transitions to P3. When defrosting is finished, V becomes V at time 14. APs returns to the level of 4 (P4=Po). This completes one cycle of the cycle of 1°6. Paying attention to the voltage fluctuations like this θ), point P reaches P2 from P. By understanding the process of change σ), it is possible to select the timing of detection of the stock box and defrosting.However, if we understand the relationship between this No. 1g change and the arrival warehouse, we can determine the most favorable conditions for the spinning mill. The cooler can be operated efficiently by operating the defrost heater at all times.The location of the cooler box is as follows:
Since it is almost determined by the structure of the cooler, the positions, dimensions, etc. of the transmitting and receiving antennas can be determined as appropriate based on the frost condition of the equipment.

〔Effect of the invention〕

As described above, the present invention provides a cooler for a refrigerator.

It detects frost on the box and defrosts the detected (i K).N frost is detected from the amount of radio wave absorption of the frost, so it is possible to accurately determine the presence or absence of a box and its quantitative change. Since it can detect high N degree frost and defrost, it has the effect of increasing the operating efficiency of the refrigerator, including the cooler, and realizing energy savings.

Although the transmitting/receiving antenna of the present invention is a dipole antenna as an example, the shape of the antenna is not particularly limited (for example, it may be a loop shape, and its arrangement may be in the space between the radiation fins). internal or external σ)
It is preferable to arrange transmitting and receiving antennas nearby, and the number of antennas is at least one set, but it is also possible to combine multiple sets to further improve the detection accuracy. However, in either case, the antenna needs to be electrically insulated so that it can transmit and receive radio waves, and it is more effective if the surface is insulated.

In addition, as a means of signal processing, 12. At what stage should changes in the detected output voltage be detected? ;) However, by memorizing the initial value before N and setting the signal value when the signal value changes by a certain value from this initial value as the reference signal level for control, the signal level is set to this value. It is better to perform control when the reference value is reached, or to instruct defrosting by detecting either the 1g change or a slope with a certain slope, or when the signal or minimum value is reached. .

[Brief explanation of the drawing]

Figure 1 is an MR side view of a general refrigerator-freezer, Figures 1 and 2 are the same (a schematic diagram of the structure of the cooler, Figure 3 is a sectional view of a freezer according to an embodiment of the present invention, and Figure 4 is a main part of it) The enlarged schematic diagram and block diagram, Figure 5 and Figure 6 are characteristic diagrams for explaining the present invention. ...Cooler, 18...Radiation fin, 22...Transmission antenna, 26
...Receiving antenna, 35...Box, 44...Detector, 45...Amplifier, 46...Control circuit. , 15° / Figure 4, next Figure 6 Figure 8

Claims (1)

[Claims] 1. The air cooled by the cooler is circulated by a blower driven by a fan motor to cool the inside of the refrigerator. σ)N frost is detected and based on the detected value. In a frost detection device for a refrigerator, a defrost circuit equipped with a defrost heater is activated, and the sheath can be removed by heat training by the defrost heater. It is characterized by disposing a radio wave transmitting antenna and a receiving antenna, transmitting and receiving radio waves between the two antennas, and defrosting by detecting frost from changes in the reception No. 4 level due to frost. Refrigerator frost detection device.