JP2000320948A - Frosting detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frosting detecting device to accurately detect a frosted state throughout the whole of an evaporator. SOLUTION: A frosting detecting device for a refrigerator comprises a refrigerator consisting of a compressor, a condenser, an expansion valve, an evaporator 2, and a refrigerant; a refrigerator for cooling through circulation of the refrigerant and evaporation of it by the evaporator 2; and ultrasonic sensors 31, 31A, 32A situated opposite to each other at the two end part of the evaporator 2 and making a pair. The evaporator k2 comprises a refrigerant line 21 connected to a piping and vaporizing a refrigerant 19, sand a plurality of fins 2A-2M disposed in the refrigerant line 21 and absorbing heat from the circumference of the evaporator 2 and transferring heat to the refrigerant in the refrigerant line 21. A plurality of fins 2A-2M have a through-hole linearly extending through and constitute a propagation route for ultrasonic signals 3a and 3b from the ultrasonic sensors 31 making a pair through the through-hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frost adhering detecting device for detecting the amount of frost adhering to fins of an evaporator, and more particularly, to an open showcase refrigerator used in a supermarket or a convenience store. The present invention relates to a frost adhesion detection device.

[0002]

2. Description of the Related Art A frost adhesion detection device according to the prior art is described in (1)
A temperature-measuring resistor is directly provided on one of the fins of the evaporator 2, for example, 2A, or (2) a structure having a shape similar to the fins 2A to 2M to which frost is adhered and the temperature measured on this structure A sensor including a resistance temperature detector is provided near the evaporator 2, and the temperature monitoring by the resistance temperature detector detects frost adhering to the fins 2 </ b> A to 2 </ b> M of the evaporator 2.

As a method for detecting the adhesion of frost using an ultrasonic sensor, Japanese Patent Application Laid-Open No. 61-41869, "Method for detecting frost adhesion"
Is disclosed. In FIG. 4, reference numeral 51 denotes a measured part 52 of the evaporator 2 which absorbs heat in the refrigerator and cools a certain space.
Is a sensor block provided to face the vicinity of. The sensor block 51 includes a transmitter 53 for transmitting an ultrasonic wave to the measured section 52, and a receiver 54 for transmitting the ultrasonic wave transmitted from the transmitter 53 and reflected by the measured section 52. The transmitter 53 is connected to a continuous wave oscillator 55 that excites to transmit an ultrasonic wave, and the receiver 54 converts the received wave until the output voltage of the transmitter 53 becomes almost the same as the absolute value. An amplifier 56 for amplification is connected. And the oscillator
The output voltage of 55 and the output signal of amplifier 56 are compared by phase comparator 57 to detect a phase shift between both output voltages.

In this configuration, it is assumed that the phase shift between the two output voltages is set to zero at a predetermined distance α between the measured section 52 and the sensor block 51, and the measured section 52 has a thickness of frost adhesion. Assuming that the output voltage is shifted by Δd, by measuring the phase difference between the two output voltages, the measured portion 52 can measure the frost adhesion thickness Δd.

[0005]

As described above, the frost adhesion detecting device according to the prior art does not detect the frost adhesion state of the entire evaporator, but detects a fin or a frost adhesion sensor of a part of the evaporator. Frost on the fins is detected.
Since the length of the evaporator is as long as several tens of cm to nearly 2 m, it is difficult to grasp the entire amount of frost by local frost detection. Even if it is estimated, it may be different from the actual one.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to solve the above-mentioned problems and to provide a frost adhesion detection device which can more correctly detect the frost adhesion state over the entire evaporator. is there.

[0007]

Means for Solving the Problems To achieve the above object, a frost adhesion detection device according to the present invention comprises a compressor, a condenser, an expansion valve, an evaporator, and these devices connected by piping. A refrigerator that fills a cooling device that constitutes a circulation system with refrigerant, circulates through these devices, evaporates and cools with an evaporator, and a pair of ultrasonic waves that are installed opposite to both ends of the evaporator In a frost adhesion detection device for a refrigerator including a sensor, the evaporator is connected to a pipe and a refrigerant pipe for evaporating the refrigerant,
A plurality of fins arranged in the refrigerant pipe and absorbing heat from a peripheral portion of the evaporator to transfer the heat to the refrigerant in the refrigerant pipe. It has a through-hole penetrating in a shape, and constitutes a propagation path of an ultrasonic signal of an ultrasonic sensor which is formed in a pair via these through-holes and opposed to each other.

With this configuration, the frost adhesion detecting device transmits an ultrasonic signal from one ultrasonic sensor, and receives and receives an ultrasonic signal from a propagation path including a through hole with the other ultrasonic sensor. The amount of frost adhering to the evaporator fins can be detected from the ultrasonic signal level.

In the above frost adhesion detecting device, a pair of second ultrasonic sensors is provided outside the fins of the evaporator, and the propagation path of the second ultrasonic sensor transmits an ultrasonic signal from a through hole. The propagation path length can be parallel to the propagation path of the first ultrasonic sensor to be transmitted and received, and the same as the propagation path length of the first ultrasonic sensor.

With this configuration, the amount of frost adhering to the fin of the evaporator is detected from the ratio of the ultrasonic signal level received by the first ultrasonic sensor to the ultrasonic signal level received by the second ultrasonic sensor. Can be.

Further, the transmitting side and the receiving side of the paired ultrasonic sensors can be switched alternately. With this configuration, it is possible to correct the bias characteristic of frost adhesion detection with respect to the beam spread characteristic of the ultrasonic signal transmitted by the ultrasonic sensor.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a main part of a frost adhesion detecting device provided in an evaporator of a refrigerator as one embodiment of the present invention, FIG. 2 is a diagram showing a main part of a refrigerator, and FIG. FIG. 5 is an explanatory diagram illustrating a reception level of an ultrasonic signal depending on whether or not frost is attached.

In FIG. 2, a refrigerator according to the present invention comprises a compressor 11, a condenser 12, a dryer 13, a capillary tube or expansion valve 14, an evaporator 2, and these devices 11 to
A cooling system comprising: a pipe 16 connecting the fuel cells 14 and 2 to form a circulation system;
And a refrigerant (gas 18 and liquid 19) that circulates through the inside of the evaporator 2 and evaporates in the evaporator 2 for cooling. In FIG. 1, a pair of ultrasonic sensors 31 and 32 shown by solid lines and arranged opposite to both ends of the evaporator 2 are provided.

The evaporator 2 is connected to a pipe 16 and connected to a refrigerant 19.
And a plurality of fins arranged in the refrigerant line 21 for absorbing heat from the peripheral portion of the evaporator 2 and transferring the heat to the refrigerant 19 in the refrigerant line 21. 2A-2M,
The plurality of fins 2A to 2M have through-holes 2a to 2m penetrating in a straight line, and the ultrasonic sensors which are paired and disposed facing each other through these through-holes 2a to 2m are provided. 31,32
A propagation path 33 for the ultrasonic signals 3a and 3b can be configured.

With this configuration, the ultrasonic signal 3a is transmitted from one ultrasonic sensor (for example, 31), and the ultrasonic signal 3b from the propagation path 33 including the through holes 2a to 2m is transmitted by the other ultrasonic sensor 32. The amount of frost adhering to the fins 2A to 2M of the evaporator 2 can be detected from the level of the received and received ultrasonic signal 3b.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the structure of a refrigerator and the principle of cooling will be described.
In FIG. 2, the refrigerator includes the compressor 11 and
A cooling device including a condenser 12, a dryer 13, a capillary tube or an expansion valve 14, an evaporator 2, and a pipe 16 connecting these devices 11 to 14, 2 and forming a circulation system; This cooling device is filled with these devices 11-14, 2,
Refrigerants 18 and 19 which circulate in 16 and evaporate and cool in evaporator 2
And is provided.

[0017] With this configuration, the refrigerator is provided with the refrigerants 18, 19
The cooling is performed by using the cycle of evaporation and condensation and liquefaction. The refrigerant liquid 19 evaporates in the evaporator 2 at a temperature corresponding to the pressure. At this time, if the temperature of the evaporator 2 is lower than the ambient temperature, the heat is absorbed from the surroundings and evaporation continues, and if the pressure of the evaporator 2 is kept constant, the evaporator 2 can be kept at a constant temperature corresponding to this pressure. it can. The refrigerant liquid 19 is decompressed by the expansion valve 14 and sent to the low-pressure evaporator 2 where it absorbs the surrounding heat and evaporates, and the generated steam 18 is sucked into the compressor 11,
Compressed by the power applied to the
Then, the gas 18 is led to the condenser 12, liquefied by radiating heat to water, the atmosphere, and the like, received in the liquid reservoir, and guided to the expansion valve 14 to form a cooling cycle.

The refrigerants 18 and 19 are mediums for transferring heat. In this case, the refrigerants 18 and 19 are in a gaseous state (18) or a liquid state.
It only changes to (19). By repeating this cycle, the temperature of the object in a limited portion around the evaporator 2 can be reduced, and freezing (cooling) can be generated. That is, the refrigeration cycle spends work, (1) absorbs heat at a low temperature location (evaporator 2), and (2) spends it at a high temperature location (condenser 12). Dissipates heat with heat equivalent to the work done. The compressor 11 functions as a heat pump that draws heat by the applied power.

As described above, in the evaporator 2, when the pressure of the liquid refrigerant 19 is kept low, the liquid refrigerant 19 evaporates at a low temperature. At this time, a large amount of heat is required for the liquid refrigerant 19 to evaporate. Since the heat is removed from the surroundings and evaporates, the surroundings can be cooled. While the liquid refrigerant 19 evaporates and evaporates, the evaporation temperature with respect to the pressure is constant, and the heat taken is consumed for a state change (from liquid to gas).

Further, the compressor 11 sucks the vapor of the refrigerant 18 evaporating rapidly in the evaporator 2 into the cylinder, and can always keep the evaporator 2 at a low pressure and keep the evaporation temperature of the refrigerant 18 low. In order to discharge a large amount of heat from the gas refrigerant 18 which is a heat carrier, the pressure is increased and the condensation temperature is increased,
Heat radiation can be facilitated by setting it higher than the outside air.

The condenser 12 can liquefy the gaseous refrigerant 18 which has been heated to a high temperature and a high pressure by the compressor 11 by cooling it with ambient air or water at normal temperature. When the gas refrigerant 18 condenses and returns to the liquid refrigerant 19, the latent heat of the condensation is released to the outside air or water. Therefore, the temperature of the liquid refrigerant 19 itself in the condenser 12 does not change much. The dryer 13 removes moisture, dust, and the like contained in the liquid refrigerant 19, and prevents qualitative deterioration of the refrigerants 18, 19,
Recycling of refrigerants 18 and 19 is made possible.

Since the pressure of the capillary tube or expansion valve 14 is too high if the refrigerant 19 liquefied in the condenser 12 is too high, the pressure is reduced to a pressure at which the evaporator 2 can easily evaporate. Both means of the capillary tube or expansion valve 14 provide resistance through the narrow passage and the pressure of the refrigerant 19 drops sharply due to the throttle change. Due to the throttling effect, a part of the refrigerant 19 evaporates to generate air bubbles. At this time, the evaporation is performed not by external heat but by removing heat of the refrigerant liquid itself. (Embodiment 1) In FIG. 1, the frost adhesion detecting device of the refrigerator has ultrasonic sensors 31, 32 paired with both ends of a transmission path 33 formed by through holes 2a to 2m of fins 2A to 2M of the evaporator 2. Are arranged facing each other. The evaporator 2 absorbs heat from a peripheral portion of the evaporator 2 and transfers the heat to the refrigerants 18 and 19, and a plurality of fins having through holes that penetrate linearly.
2A to 2M, and a refrigerant pipe 21 for evaporating the refrigerants 18 and 19, and the refrigerant pipe 21 is connected to the pipe 16 to form a cooling device.

With such a configuration, the through holes of the fins 2A to 2M
For example, an ultrasonic signal 3a is transmitted from the ultrasonic sensor 31 through 2a to 2m, and an ultrasonic signal 3b is received by the ultrasonic sensor 32 arranged opposite thereto. Now, the through holes 2a of the fins 2A to 2M
When the propagation path of the ultrasonic signals 3a and 3b is set so as to pass through the center of 2m, and is set to a predetermined diameter of the through holes 2a to 2m, the ultrasonic signal 3b passing through the through holes 2a to 2m is The ultrasonic sensor 32 can receive the ultrasonic signal 3b, since the hole diameter or the ultrasonic passage area of the through holes 2a to 2m varies depending on the degree of frost adhered to the fins 2A to 2M. Thus, the amount of frost on the fins 2A to 2M of the evaporator 2 can be detected.

FIG. 3 is an explanatory diagram for explaining the reception level of an ultrasonic signal depending on whether or not frost has adhered. FIG. 3A shows a state in which no frost is attached to the fins 2A to 2M of the evaporator 2,
(B), the ultrasonic sensors 31 and 3 arranged facing each other at this time
2 illustrates transmission / reception signals 3a and 3b of the second ultrasonic signal. FIG. 3 (C) shows a state in which frost adhered to the fins 2A to 2M of the evaporator 2 and closed the through holes 2a to 2m, resulting in an ice state. FIG. 3 (D) shows an ultrasonic wave at this time. FIG. 3 illustrates transmission / reception signals 3a and 3b of the ultrasonic signals of the sensors 31 and 32.

In FIG. 3A, the ultrasonic sensor 31 on the transmitting side irradiates the ultrasonic beam 3a to the ultrasonic sensor 32 on the receiving side through the through holes 2a to 2m. The irradiating ultrasonic beam 3a is an intermittently emitted ultrasonic signal of a pulse oscillation having a high Q value determined by the electro-acoustic vibration frequency of the ultrasonic sensor 31, or an ultrasonic signal of a continuous sine wave signal. Sensor
Even with the ultrasonic signal driven by this excitation waveform
An ultrasonic signal of any waveform may be used. Ultrasonic sensor
The ultrasonic beam 3a emitted from 31 is
According to the relationship between the beam spreading diameter of 3a and the through diameter of the through holes 2a to 2m, the beam spreading diameter is large, and there is a loss of some ultrasonic beams 3a that cannot pass through the through hole of the through holes 2a to 2m, Most of the ultrasonic signals can be received by the ultrasonic sensor 32 as the ultrasonic beam 3b (see FIG. 3B).

FIG. 3C shows a state in which frost adheres to the fins 2A to 2M of the evaporator 2 to block the through holes 2a to 2m and becomes an ice state. As shown by the dotted line in (D), the ultrasonic sensor 3 on the receiving side cannot receive the ultrasonic beam 3b. (Embodiment 2) Next, another embodiment will be described. In FIG. 1, the second frost adhesion detection device of the first embodiment is paired with the frost adhesion detection device of the first embodiment.
The ultrasonic sensors 31A and 32A are disposed outside the fins 2A to 2M of the evaporator 2, and the propagation paths 33 of the second ultrasonic sensors 31A and 32A are provided.
a is parallel to the propagation path 33 of the first ultrasonic sensors 31 and 32 for transmitting and receiving the ultrasonic signals 3a and 3b from the through holes 2a to 2m, and
The propagation path length can be the same as the propagation path length of the ultrasonic sensors 31 and 32.

With this configuration, the ratio between the level of the ultrasonic signal 3b received by the first ultrasonic sensor 32 and the level of the ultrasonic signal 3d received by the second ultrasonic sensor 32A is applied to the fins 2A to 2M of the evaporator 2. The amount of frost to be generated can be detected.

In particular, by adopting such a configuration, environmental conditions such that steam is trapped around the evaporator 2 and a part of the ultrasonic beams 3a and 3b are affected by absorption or reflection / scattering by the steam. Even if the condition is poor, by disposing the propagation path 33a of the second ultrasonic sensors 31A and 32A near the fins 2A to 2M of the first ultrasonic sensors 31 and 32 in parallel with the propagation path 33, for example, steam can be trapped. For example, the influence of environmental conditions around the evaporator 2 is calculated by calculating the ratio between the level of the ultrasonic signal 3b received by the first ultrasonic sensor 32 and the level of the ultrasonic signal 3d received by the second ultrasonic sensor 32A. ,
Compensation can be performed, and more accurate calculation can be performed.

In the first and second embodiments, the transmitting side and the receiving side of the paired ultrasonic sensors (31, 32) and (31A, 32A) can be switched alternately. With this configuration, the transmitting side and the receiving side of the ultrasonic sensors (31, 32) and (31A, 32A) are alternately switched to transmit and receive ultrasonic signals (3a, 3b), (3
By alternately changing the directions of (c, 3d), the frost adhesion state is classified, for example, into the fins 2A or the fins 2M, and the frost adhesion state over the entire fins 2A to 2M of the evaporator 2 is detected. Can be monitored.

[0030]

As described above, according to the present invention, the ultrasonic beam is irradiated to the ultrasonic sensor on the receiving side through the through hole of the fan of the evaporator, and the ultrasonic signal level is measured. In addition, it is possible to detect the frost adhesion state over the entire fan of the evaporator.

[Brief description of the drawings]

FIG. 1 is a main configuration diagram of a frost adhesion detection device provided in an evaporator of a refrigerator as one embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of a refrigerator.

FIG. 3 is an explanatory diagram illustrating a reception level of an ultrasonic signal according to the presence or absence of frost adhesion.

FIG. 4 is a main part configuration diagram of a frost adhesion detection method according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigerator 11 Compressor 12 Condenser 13 Dryer 14 Expansion valve 16 Piping 18 Refrigerant (gas) 19 Refrigerant (liquid) 2 Evaporator 21 Refrigerant line 2A-2M Fin 2a-2m Through hole 31,31A, 32,32A Acoustic sensor 33, 33a Propagation path 3a to 3d Ultrasonic signal 51 Sensor block 52 Device under test 53 Transmitter 54 Receiver 55 Oscillator 56 Amplifier 57 Phase comparator α distance Δd Frost thickness

Claims (4)

[Claims] 1. A compressor, a condenser, an expansion valve, an evaporator, and a cooling system which connects these devices by piping to form a circulating system and is filled with a refrigerant, circulates in these devices and evaporates. A frost adhesion detection device for a refrigerator, comprising: a refrigerator that cools by evaporating in a refrigerator; and a pair of ultrasonic sensors that are disposed opposite to both ends of the evaporator. A refrigerant pipe connected to evaporate the refrigerant, and a plurality of fins arranged in the refrigerant pipe, which absorb heat from a peripheral portion of the evaporator and transfer the heat to the refrigerant in the refrigerant pipe. The plurality of fins have through holes that penetrate in a straight line, and constitute a pair of ultrasonic sensors through which the ultrasonic signals are propagated. A frost adhesion detection device characterized by the above-mentioned. 2. An apparatus for detecting frost adhesion according to claim 1, wherein one of the ultrasonic sensors transmits an ultrasonic signal, and the other ultrasonic sensor receives an ultrasonic signal from a propagation path including a through hole. Detecting the amount of frost adhering to the fins of the evaporator from the received ultrasonic signal level. 3. The frost adhesion detecting device according to claim 1, wherein a pair of second ultrasonic sensors is provided outside the fins of the evaporator, and the propagation path of the second ultrasonic sensors is from the through hole. The propagation path length is parallel to the propagation path of the first ultrasonic sensor for transmitting and receiving the ultrasonic signal, and is the same as the propagation path length of the first ultrasonic sensor. The level of the ultrasonic signal received by the first ultrasonic sensor and the second A frost adhering detection device, wherein the amount of frost adhering to a fin of an evaporator is detected from a ratio with an ultrasonic signal level received by an ultrasonic sensor. 4. The apparatus for detecting frost adhesion according to claim 1, wherein the transmitting side and the receiving side of the paired ultrasonic sensors are alternately switched.