JP2000337741A - Refrigerant leakage detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automated refrigerant leakage detecting device wherein a need to mount a sight glass on a refrigerant pipe is eliminated and the occurrence of an erroneous detecting during full operation of a refrigerator is prevented. SOLUTION: In a refrigrator to perform cooling by filling a cooling device with refrigerants 31 and 32, an ultrasonic sensor 23 is provided to obliquely radiate ultrasonic continuous wave beams 2a to the flow of a refrigerant in a refrigerant pipe 17, a scattering wave 2c produced by scattering the ultrasonic continuous wave beams 2a are scattered by air bubbles 33 of the refrigerant is received by the ultrasonic sensor 23 and a signal processing circuit 5A is provided to process the receipt signal 22c. The signal processing circuit 5A determines a velocity of pass flow of the refrigerant 32 from a deviation frequency Δf2 between a transmission frequency f1 and a receipt frequency f1±Δ f2 of the ultrasonic sensor 23, determines an air bubble generating amount in the refrigerant from the amplitude of a deviation frequency signal, and computes a reference value from a bubble amount (presence and absence) characteristic curve on the basis of a velocity of flow. When the air bubble generating amount exceeds a reference value, it is decided that leakage of the refrigerant occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device (hereinafter, abbreviated as a refrigerator) provided with an open showcase refrigerant used in a supermarket, a convenience store, and the like, and particularly to a refrigerant leak detection for detecting the refrigerant leak. Related to the device.

[0002]

2. Description of the Related Art Refrigerant leak detection according to the prior art has been carried out by visually observing air bubbles appearing on a sight glass in which a state of a refrigerant pipe provided downstream of an expansion valve can be directly viewed. Normally, the refrigerant is sealed in the refrigerant pipe at high pressure, so that the evaporation temperature is high and the liquid is liquid at room temperature, but when the refrigerant leaks, the pressure in the refrigerant pipe decreases, the evaporation temperature decreases, and the room temperature decreases. But it becomes gaseous. Using this principle, the amount of air bubbles appearing on the sight glass was visually monitored to estimate the amount of refrigerant leakage.

[0003] Fig. 11 shows a summary of the lecture papers of the "Air Conditioning Refrigerant Sensor", Academic Lecture Meeting of the Japan Refrigeration Association in 1992.
(4-11-30,12-1 Tokyo) It is a conceptual diagram of the refrigerant leak detection sensor announced. In FIG. 11, according to the method of the disclosed concept B, the light-emitting element 41 and the light-receiving element 42 are provided in the refrigerant flow path via the sight glass 43 provided in the refrigerant pipe 17.
Are arranged opposite to each other, and detect the amount of transmitted light that changes depending on the state of the bubbles 33 appearing in the refrigerant 32. That is,
When the amount of the refrigerant is appropriate, no bubbles 33 are generated between the receiver dryer and the expansion valve, so that the amount of transmitted light is high, and when the refrigerant is insufficient, the bubbles 33 are generated.
The light transmission is reduced. The amount of transmitted light is determined by the signal processing circuit.
The voltage is converted by 45 and the two light emitting elements, green LED46 and red LE
Displayed on D47. According to this paper, it is reported that leaks can be detected in the range of about 7 to 13% of the appropriate filling amount in an air conditioning system.

Although not shown, as a concept A, a heating element is provided in the refrigerant flow path, and the heating element changes depending on the state of the refrigerant by utilizing the difference between the gas thermal conductivity and the liquid thermal conductivity of the refrigerant. There has been reported a refrigerant leak detection method for detecting the degree of cooling of the refrigerant.

[0005]

As described above, the refrigerant leakage detecting method according to the prior art is based on (1) a visual method through a sight glass, (2) a detecting method based on a difference in light transmission amount in the refrigerant, or (3) There is a detection method based on the difference in the thermal conductivity of the refrigerant. (1) There is a problem that the visual method of manually detecting the refrigerant leak cannot be automated and the inspection cost increases. Also, (1),
In either of the methods (2) and (3), it is necessary to provide a sight glass in the refrigerant pipe, or to install a heating element in the refrigerant, and the pipe needs to be treated accordingly.

In the method of detecting a refrigerant leak only by the generation of refrigerant bubbles according to (2) and (3), for example, when a large amount of commodities are refilled in a showcase at one time, the temperature in the refrigerator is reduced. When the refrigerator rises and the refrigerator runs at full capacity, a phenomenon occurs in which the pressure in the high-pressure refrigerant pipe temporarily drops, and the method according to the related art has a problem that the refrigerant is erroneously detected as leaking even though it does not leak.

[0007] 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 eliminate the need for processing a refrigerant pipe such as providing a sight glass.
An object of the present invention is to provide an automated refrigerant leak detection device that can prevent erroneous detection when a refrigerator is in full operation.

[0008]

In order to achieve the above object, a refrigerant leak detecting device for a refrigerator according to the present invention connects a compressor, a condenser, an expansion valve, an evaporator, and these devices to form a circulation system. A cooling device comprising a piping that constitutes the cooling device; a refrigerant filled in the cooling device, circulated through these devices, and evaporated and cooled by an evaporator, and one side of a high-pressure side refrigerant pipe connected to the evaporator. A first ultrasonic sensor, which is disposed obliquely and emits an ultrasonic continuous wave beam obliquely with respect to the flow direction of the refrigerant; and a first ultrasonic sensor that continuously excites the first ultrasonic sensor. A first signal processing circuit configured to receive a scattered wave in which the ultrasonic continuous wave beam is scattered by a bubble in the refrigerant by the ultrasonic sensor and process the received signal; and the first signal processing circuit includes a first signal processing circuit. Transmission frequency transmitted by ultrasonic sensor and reception frequency received A first bubble flow rate calculating means for calculating a flow velocity of the refrigerant from the shift frequency signal, a first bubble generation amount calculating means for calculating the amount of bubbles generated in the refrigerant from the amplitude of the shift frequency signal, and a first bubble flow rate calculating means An arithmetic processing unit for calculating a reference value from a bubble amount (presence / absence) characteristic curve based on data of the means, and a comparing means for comparing data of the first bubble generation amount calculating means with the reference value. And With this configuration, when the data of the first bubble generation amount calculation means is larger than the reference value of the bubble amount (presence / absence) characteristic curve, it can be determined that there is refrigerant leakage.

A refrigerant leak detecting device for a refrigerator according to the present invention includes a cooling device including a compressor, a condenser, an expansion valve, an evaporator, and a pipe connecting these devices to form a circulation system. A refrigerant filled in the cooling device, circulated through these devices and evaporated and cooled by an evaporator, and cooled, and a refrigerant which is inclined and disposed on one side of a high-pressure side refrigerant pipe connected to the evaporator in a flow direction of the refrigerant. The first to radiate the ultrasonic continuous wave beam obliquely
An ultrasonic sensor, a second ultrasonic sensor for receiving a scattered wave in which the ultrasonic continuous wave beam of the first ultrasonic sensor is scattered by bubbles in the refrigerant, and a second ultrasonic sensor for continuously exciting the first ultrasonic sensor. A second signal processing circuit for processing a reception signal received by the ultrasonic sensor, wherein the second signal processing circuit comprises a transmission frequency transmitted by the first ultrasonic sensor and a reception frequency received by the second ultrasonic sensor. A second bubble flow rate calculating means for obtaining a flow velocity of the refrigerant from the shift frequency signal of the second and third air bubbles; a second bubble generation amount calculating means for calculating the amount of bubbles generated in the refrigerant from the amplitude of the shift frequency signal; An arithmetic processing unit for calculating a reference value from the bubble amount (presence / absence) characteristic curve based on the data of the calculation means, and a comparison means for comparing the data of the second bubble generation amount calculation means with the reference value. Shall be. With this configuration, when the data of the second bubble generation amount calculation means is larger than the reference value of the bubble amount (presence / absence) characteristic curve, it can be determined that there is refrigerant leakage.

The refrigerant leak detecting device for a refrigerator according to the present invention includes a third ultrasonic sensor vertically arranged on one side surface of another high pressure side refrigerant pipe connected to the evaporator, and a first ultrasonic sensor. Alternatively, the first ultrasonic sensor is continuously excited in place of the second signal processing circuit, and the ultrasonic signal is received by the first ultrasonic sensor or the second ultrasonic sensor to receive a scattered wave scattered by bubbles in the refrigerant. A third signal processing circuit for processing a signal, the third signal processing circuit comprising: a third bubble flow velocity calculating means for determining a passage velocity of the refrigerant from a shift frequency signal between the transmission frequency and the reception frequency; A receiving level detecting means for exciting the acoustic wave sensor in a pulse form and receiving a reflected wave returning to the ultrasonic sensor and detecting the amplitude of the third received signal, and a bubble amount determination reference based on data from the third bubble flow velocity calculating means The third to calculate the value
It is assumed that it comprises an arithmetic processing unit and comparison means for comparing data of the reception level detecting means with a reference value of the third arithmetic processing unit.

With this configuration, when the data of the reception level detecting means is lower than the bubble amount determination reference value, it can be determined that there is a refrigerant leak. Further, the refrigerant leak detection device is configured to include an electric quantity sensor that detects current consumption or power consumption of the compressor.

With such a configuration, the arithmetic processing unit of the first or second signal processing circuit allows the bubble amount (based on the current consumption or power consumption data) to be used instead of the data obtained by the first or second bubble flow rate calculation means. A reference value is calculated from the characteristic curve, and if the data of the first or second bubble generation amount calculating means is larger than the reference value of the bubble amount (presence / absence) characteristic curve, it can be determined that there is refrigerant leakage.

Further, the refrigerant leak detecting device is provided with a compressor or a pressure sensor for measuring a refrigerant pressure in an outlet refrigerant pipe of the compressor. With such a configuration,
The arithmetic processing unit of the first or second signal processing circuit calculates a reference value from the bubble amount (presence / absence) characteristic curve based on the data of the pressure sensor, instead of the data obtained by the first or second bubble flow rate calculating means. When the data of the first or second bubble generation amount calculation means is larger than the reference value of the bubble amount (presence / absence) characteristic curve, it can be determined that there is refrigerant leakage.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a main part of a refrigerant leak detecting device of a refrigerator as one embodiment of the present invention, and FIG. 2 is a main portion of a refrigerant leak detecting device of a refrigerator as another embodiment. Diagram,
3 is a main part configuration diagram of a signal processing circuit of one embodiment, FIG. 4 is a main part configuration diagram of a signal processing circuit of another embodiment, FIG. 5 is a main part configuration diagram of a signal processing circuit of another embodiment, 6 is an explanatory diagram illustrating the principle of one embodiment, FIG. 7 is an explanatory diagram illustrating a foam amount (presence / absence) characteristic curve and a foam amount determination reference value, and FIG. 8 is an explanatory diagram illustrating another principle of detecting a refrigerant leak. 9 is a timing chart for explaining the detection principle of FIG. 8, FIG. 10 is a flowchart for judging a refrigerant leak of one embodiment, and FIG. 12 is a main part configuration diagram of a refrigerant leak detecting device of a refrigerator as another embodiment. The same members corresponding to FIG. 11 are denoted by the same reference numerals. (Embodiment 1) In FIG. 1, a refrigerator according to the present invention
Compressor 11, condenser 12, dryer 13, capillary tube or expansion valve 14, evaporator 15, these devices 11
, And a piping 16 forming a circulation system, and a cooling device comprising:
Refrigerant (gas 31, liquid 32) that circulates through the inside of the evaporator 15 and evaporates in the evaporator 15 to cool.

A device for detecting leakage of the refrigerants 31 and 32 of the refrigerator has a wedge on one side of a high-pressure side refrigerant pipe 17 connected to the evaporator 15.
A first ultrasonic sensor 23 that is disposed obliquely through the first and second 24 and emits an ultrasonic continuous wave beam obliquely with respect to the flow direction of the refrigerants 32 and 33, and transmits the first ultrasonic sensor 23 to an excitation signal 22a. And the continuous ultrasonic wave 2a of the first ultrasonic sensor 23 receives the scattered wave 2c scattered by the bubbles 33 in the refrigerant (32, 33 (bubbles)). , This received signal
And a first signal processing circuit 5A for processing 22c.

In FIG. 3, the first signal processing circuit 5A detects the refrigerant from the signal of the shift frequency Δf2 between the transmission frequency f1 transmitted by the first ultrasonic sensor 23 and the reception frequency (f1 ± Δf2) received. A first bubble flow velocity calculating means (53A, 53B, 53D, hereinafter referred to as 53D) for calculating the passing flow velocity of 32, 33, and a first bubble for calculating the amount of bubbles generated in the refrigerant from the amplitude of the signal of the shift frequency Δf2. Calculation processing for calculating the reference value 5e from the characteristic curve (5E) of the bubble amount (presence / absence) based on the data of the generation amount calculation means (53A, 53B, 53C, hereinafter referred to as 53C) and the data of the first bubble flow velocity calculation means 53D. Data 5c of the section 58 and the first bubble generation amount calculating means 53C.
And a comparing means 55 for comparing the value with the reference value 5e.

With this configuration, the signal processing circuit 5A determines that there is a refrigerant leak when the data 5c of the first bubble generation amount calculating means 53C is larger than the reference value 5e of the bubble amount (presence / absence) characteristic curve (5E). Leaks can be detected. (Embodiment 2) In FIG. 2, a refrigerant leak detecting device of a refrigerator according to Embodiment 2 is different from the refrigerant leak detecting device described in Embodiment 1 above in that a high pressure side refrigerant pipe connected to the evaporator 15 is provided. 17th third vertically arranged on one side of another place
Ultrasonic sensor 25 and first or second signal processing circuit 5A, 5B
Instead of this, the first ultrasonic sensor 23 is continuously excited by the excitation signal 22a, and the ultrasonic signal 2a generates the scattered waves 2c and 2b scattered by the bubbles 33 in the refrigerant (32, 33 (bubbles)). 1 ultrasonic sensor 23
Alternatively, a third signal processing for processing the reception signals 22c and 22b received by the second ultrasonic sensor 23A shown by a dotted line, and for exciting the third ultrasonic sensor 25 in a pulse shape and receiving and processing the reflected wave 2f. And circuits 6A and 6B.

In FIG. 5, the third signal processing circuits 6A and 6B correspond to the transmission frequency f1 transmitted by the first ultrasonic sensor 23,
Third bubble for obtaining the flow velocity of the refrigerant 32, 33 from the signal of the shift frequency Δf2 with the reception frequency (f1 ± Δf2) of the reception signal 22c, 22b received by the first ultrasonic sensor 23 or the second ultrasonic sensor 23A. A flow rate calculating means (52 to 53D, hereinafter denoted by 53D); a third ultrasonic sensor 25 which is excited in a pulse form and receives a reflected wave returning to the ultrasonic sensor 25;
reception level detection means for detecting the amplitude of c (61 to 63C or less
63C) and the bubble amount determination reference value (6G) from the bubble amount determination reference characteristic (6G) based on the data 5f of the third bubble flow velocity calculating means 53D.
g) third operation processing unit 68, and reception level detection means
And a comparing means 55 for comparing the data 6c of 63C with the reference value 6g of the third arithmetic processing unit 68.

With this configuration, the third signal processing circuits 6A and 6A
B, when the data 6c of the reception level detecting means 63C is lower than the bubble amount determination reference value 6g, it is determined that there is refrigerant leakage, and refrigerant leakage can be detected.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the structure of a refrigerator and the principle of cooling will be described. In FIG. 1, the refrigerator is a compressor 11 as described above.
, A condenser 12, a dryer 13, a capillary tube or expansion valve 14, an evaporator 15, and a pipe 16 for connecting these devices 11 to 15. And refrigerants 31 and 32 that circulate in the devices 11 to 15 and 16 and evaporate and cool in the evaporator 15.

With such a configuration, the refrigerator is provided with the refrigerants 31, 32
Cooling is performed using a cycle of evaporation (31) and condensation and liquefaction (32). The refrigerant liquid 32 evaporates in the evaporator 15 at a temperature corresponding to the pressure. At this time, if the temperature of the evaporator 15 is lower than the ambient temperature, heat is absorbed from the surroundings and evaporation continues, and if the pressure of the evaporator 15 is kept constant, it can be kept at a constant temperature corresponding to this pressure. it can. The refrigerant liquid 32 is decompressed by the expansion valve 14 and sent to the low-pressure evaporator 15, where it absorbs the surrounding heat and evaporates, sucks the generated steam 31 into the compressor 11, and adds power to the compressor 11 Compressed by the high pressure and high temperature gas 31, this gas 31 is led to the condenser 12, liquefied by radiating heat to water, air, etc., received in the liquid reservoir, and guided to the expansion valve 14, A cooling cycle is formed.

The refrigerants 31, 32 are mediums for transferring heat. In this case, the state of the refrigerants 31, 32 is changed to a gaseous state (31) or a liquid state.
It only changes to (32). By repeating this cycle, the temperature of the object in a limited portion around the evaporator 15 is reduced, and freezing (cooling) can be generated. That is, the refrigeration cycle spends work, (1) absorbs heat at a low temperature location (evaporator 15), 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 15, the liquid refrigerant 32 evaporates at a low temperature when its pressure is kept low. At this time, a large amount of heat is required for the liquid refrigerant 32 to evaporate. Since the heat is removed from the surroundings and evaporates, the surroundings can be cooled. While the liquid refrigerant 32 evaporates and evaporates, the evaporating temperature with respect to the pressure is constant, and the heat taken is consumed for a state change (from liquid to gas).

The compressor 11 sucks into the cylinder the vapor of the refrigerant 31 which evaporates rapidly in the evaporator 15 and constantly evaporates the refrigerant.
15 can be maintained at a low pressure, and the evaporation temperature of the refrigerant 31 can be kept low. In order to discharge a large amount of heat from the gas refrigerant 31 which is a heat carrier, the pressure is increased to increase the condensation temperature,
Heat radiation can be facilitated by setting it higher than the outside air.

The condenser 12 is capable of cooling and liquefying the gaseous refrigerant 31 which has been heated to a high temperature and a high pressure by the compressor 11 with ambient air or water at normal temperature. When the gas refrigerant 31 condenses and returns to the liquid refrigerant 32, the latent heat of the condensation is released to the outside air or water. Therefore, the temperature of the liquid refrigerant 32 itself in the condenser 12 does not change much.

The dryer 13 removes moisture, dust and the like contained in the liquid refrigerant 32, prevents the refrigerants 31 and 32 from being deteriorated in quality, and allows the refrigerants 31 and 32 to be recycled. Capillary tube or expansion valve 14 is a refrigerant liquefied in condenser 12
Since the pressure is too high if the pressure is kept at 32, the pressure is reduced to a pressure at which evaporation in the evaporator 15 is easy. Both means of the capillary tube or expansion valve 14 provide resistance through the narrow passage and the pressure of the refrigerant 32 drops abruptly due to throttle changes. Due to the throttling effect, part of the refrigerant 32 evaporates and bubbles 33
However, evaporation at this time is performed not by external heat but by removing heat of the refrigerant liquid 32 itself. (Embodiment 1) A first signal processing circuit 5A for processing a received signal 22c according to the configuration of Embodiment 1 will be described with reference to the principle explanatory diagram of FIG. In FIG. 6, the first ultrasonic sensor 23 is continuously excited by a sine wave having a frequency f1 from the excitation unit 52. This first
The ultrasonic sensor 23 obliquely emits a sinusoidal ultrasonic continuous wave beam 2a having a frequency f1. The ultrasonic continuous wave beam 2a scatters a scattered wave 2c scattered by bubbles 33 in the refrigerants 32 and 33. Received by the sensor 23. The frequency of the scattered wave 2c received at this time is proportional to the flow velocity of the refrigerants 32 and 33, and a frequency shift occurs by the Doppler shift frequency (± Δf2) whose sign is determined by the flow direction of the refrigerants 32 and 33. (F1 ± Δf2).
At this time, the detection signal 22c detected by the first ultrasonic sensor 23 is detected as a signal waveform of a product of the sine wave signals of both frequencies (f1) and (f1 ± Δf2).

The product of the sine wave signals of the two frequencies (f1, (f1 ± Δf2)) is the sum (2f1 ± Δf2) of the two frequencies and the difference
(± Δf2) can be expressed in the form of a sum of sinusoidal signals, and the frequency (2f1 ± Δf2) is a high-frequency signal and the frequency (± Δf2
Since 2) is a low-frequency signal, the Doppler shift frequency component (± Δf2) is detected by removing the high-frequency component through the low-pass filter 53B, and the flow rates of the refrigerants 32 and 33 can be calculated.

Next, in FIG. 3, the first signal processing circuit 5A
Will be described. The first signal processing circuit 5A is a first ultrasonic sensor
An exciting unit 52 for exciting the 23, a receiving unit 53 including an amplifier 53A for amplifying the detection signal 22c, a low-pass filter 53B, an amplitude detecting unit 53C, and a frequency detecting unit 53D, a comparator 55, a storage circuit 56, and a central processing unit. (CPU) 57 and an arithmetic unit 54 including an arithmetic processing unit 58.

In such a configuration, the first signal processing circuit 5A
Means that the frequency f1 and the frequency (f1 ± Δf2) are the first ultrasonic sensor 2
3 The detection signal 22c mixed by itself is amplified by the amplifier 53A, and the high-frequency component (2f1 ± Δf
2) is filtered to detect the Doppler frequency deviation ± Δf2, and the amplitude detector 53C detects the amplitude value of the Doppler frequency deviation ± Δf2, that is, the generation amount 5c of the bubble 33 (first bubble generation amount calculation). Means 53C), the frequency Δf2 is detected by a frequency detector 53D, for example, a counter (first bubble flow rate calculating means 53D), and the refrigerant
The flow velocity 5f of 32,33 can be detected.

Based on the detected value of the flow rate 5f of the refrigerants 32 and 33, the arithmetic unit 54 calculates the flow rate 5f based on the bubble amount (presence / absence) characteristic curve 5E shown in FIG. And the reference value 5e corresponding to the flow velocity 5f is calculated by the arithmetic processing unit 58 by, for example, a proportional calculation, and the data (the generation amount of the bubbles 33) 5c of the first bubble generation amount calculation means 53C and the reference value are calculated. By comparing the value 5e with the comparing means 55, the presence or absence of refrigerant leakage can be determined. (Example 2) Another example of Embodiment 1 will be described. FIG.
In the other embodiments, the leak detecting device for the refrigerants 31 and 32 of the refrigerator according to the other embodiment includes a high-pressure refrigerant pipe 17 connected to the evaporator 15 of the refrigerator.
Of the refrigerant 32, 33
A first ultrasonic sensor 23 that radiates an ultrasonic continuous wave beam obliquely to the flow direction of the first ultrasonic sensor 23, and the ultrasonic continuous wave beam 2a of the first ultrasonic sensor 23 is used in the refrigerant (32, 33 (bubbles)). A second ultrasonic sensor 23A for receiving a scattered wave 2c scattered by the bubble 33,
The first ultrasonic sensor 23 is continuously excited by the excitation signal 22a,
And a second signal processing circuit 5B for processing the reception signal 22c received by the second ultrasonic sensor 23A.

The second signal processing circuit 5B excites the first ultrasonic sensor 23 by the excitation unit 52, and transmits a transmission frequency f1 transmitted by the first ultrasonic sensor 23, a reception frequency (f1 ± Δf2) to receive, and
A second bubble flow velocity calculating means 53D for obtaining the flow velocity of the refrigerant 32, 33 from the signal of the frequency deviation Δf2 of the frequency deviation Δf2;
The reference value 5d is calculated from the bubble amount (presence / absence) characteristic curve 5D based on the data of the second bubble generation amount calculating means 53C for obtaining the amount of bubbles generated in the refrigerant from the amplitude of the signal and the second bubble flow rate calculating means 53D. An arithmetic processing unit 58 and a comparing means 55 for comparing the data 5b of the second bubble generation amount calculating means 53C with the reference value 5d can be provided.

In FIG. 4, the second signal processing circuit 5B comprises an excitation section 52 for exciting the first ultrasonic sensor 23, an amplifier 53A for amplifying the detection signal 22b received by the second ultrasonic sensor 23A, and an amplifier 53A 53A output and frequency f from excitation unit 52
(1) a mixing section 53E for mixing the signal 1; a low-pass filter 53B; a reception section 53M including an amplitude detection section 53C and a frequency detection section 53D; a comparator 55; a storage circuit 56; a central processing unit (CPU) 57; Arithmetic unit 54 comprising unit 58
And is provided.

In such a configuration, the second signal processing circuit 5B
Excites the first ultrasonic sensor 23 with the excitation unit 52,
The ultrasonic sensor 23 radiates the ultrasonic continuous wave beam 2a obliquely to the flow direction of the refrigerant 32, 33, and the ultrasonic continuous wave beam 2a generates the scattered wave 2b scattered by the bubble 33 in the refrigerant 32, 33. Second
Received by the ultrasonic sensor 23A, the second ultrasonic sensor 23A
The amplifier 53A amplifies the reception frequency (f1 ± Δf2) received by the amplifier 53A, and the output 53a of the amplifier 53A and the frequency from the excitation unit 52
The signal 52a of f1 is mixed with, for example, a non-linear element of the mixing unit 53E to form a product signal of sine wave signals of two frequencies (f1, (f1 ± Δf2)).
The low-pass filter 53B filters out the high-frequency component (2f1 ± Δf2) to detect the Doppler frequency deviation ± Δf2, and the amplitude detector 53C determines the amplitude value of the Doppler frequency deviation ± Δf2, that is, the amount 5b of generated bubbles 33. Is detected (second air bubble generation amount calculation means 53C), and the frequency Δ
By detecting f2 (second bubble flow velocity calculating means 53D), the flow velocity 5f of the refrigerants 32, 33 can be detected.

Then, the arithmetic unit 54 outputs the detected refrigerant 3
Based on the flow rate 5f of 2,33, the data near the detected value of the flow rate 5f is read out from the foam amount (presence / absence) characteristic curve 5D shown in FIG.
The reference value 5d corresponding to 5f is calculated by the arithmetic processing unit 58, and the data (the amount of generated bubbles 33) 5b of the first bubble generation amount calculation means 53C is compared with the reference value 5d by the comparison means 55, and the refrigerant leakage is calculated. Can be determined. In particular, when the signal level for receiving the scattered wave 2b is lower than that of the first embodiment, the scattered wave 2b is individually received by the second ultrasonic sensor 23A, and the amplified scattered wave 2b is amplified.
By mixing the signals of the excitation unit 52 and the received and amplified scattered wave 2b with the mixing unit (53E) through the nonlinear element, the signal of the Doppler frequency shift ± Δf2 can be detected more stably. Hereinafter, it is possible to determine the presence or absence of refrigerant leakage by the same processing as described in the first embodiment.

Further, as another embodiment different from the embodiments described in the first and second embodiments, there is a refrigerant leak detecting device shown in FIG. In FIG. 12, the refrigerant leak detection device is a compressor
11 Electric quantity sensor 27 that detects current consumption or power consumption
Alternatively, the compressor 11 or the outlet refrigerant pipe of the compressor 11 may be provided with a pressure sensor 28 for measuring a refrigerant pressure.

With such a configuration, the arithmetic processing unit 58 of the first signal processing circuit 5C or the arithmetic processing unit 58 of the second signal processing circuit 5D
(See FIGS. 3 and 4), first or second bubble flow velocity calculating means
Instead of the data 5f obtained by 53D, the reference values 5e, 5d are calculated from the bubble amount (presence / absence) characteristic curves 5E, 5D based on the data of the current consumption or the power consumption, and the first or second bubble generation amount calculating means 53C Data 5c and 5b are the reference values of the foam amount (presence / absence) characteristic curve
When it is larger than 5e, 5d, it can be determined that there is refrigerant leakage. (Embodiment 3) The embodiment 2 will be supplementarily described. Embodiment 1 described in Embodiment 1 and Embodiment 2 and Embodiment 2 of the present invention
The difference is as follows. That is, in the first embodiment, the detection of the generation amount 5c, 5b of the bubble 33 in the refrigerant pipe 17 is performed by using the scattered waves 2c, 2b scattered by the bubble 33 in the first ultrasonic sensor 23 or the second ultrasonic sensor. This is performed by detecting the amplitude of the frequency component obtained by Doppler frequency deviation ± Δf2 at 23A. On the other hand, in the second embodiment, the third ultrasonic sensor 25 is installed vertically at another position in the refrigerant pipe 17, and the reflected wave reflected by the refrigerant pipe 17 is measured. The amount of generation 6c, 6b is detected indirectly. That is, the third
Although the ultrasonic signal from the ultrasonic sensor 25 is scattered by the bubbles 33, the amount of ultrasonic transmission that passes through the remaining refrigerant pipe 17 is measured. The third signal processing circuits 6A and 6B are shown in FIG. The signal processing circuit 6A corresponding to the first embodiment will be mainly described, and the signal processing circuit 6B corresponding to the second embodiment will be described in parentheses.

In FIG. 5, the third signal processing circuit 6A (6B)
Are the excitation unit 52 for exciting the first ultrasonic sensor 23 corresponding to the first embodiment (2), and the detection signal 22c received by the first ultrasonic sensor 23 (or the detection signal received by the second ultrasonic sensor 23A). 22b), (a mixing unit 53E for mixing the output of the amplifier 53A and the signal of the frequency f1 from the excitation unit 52), a low-pass filter 53B and a frequency detection unit 53D. Form a part, refrigerant pipe 17
Third bubble flow velocity calculating means (52 to 53D) for determining the flow velocity of the bubble 33 inside, a timing generator 61 for generating pulses at regular intervals, and the third ultrasonic sensor 25 is excited upon receiving this timing pulse. The receiving section 63 includes a transmitting section 62, an amplifier 63A, a band-pass filter 63B, and an amplitude detecting section 63C.
, A reception level detecting means (61-63C) for detecting a reflected wave 2f passing through the bubble 33 in the refrigerant pipe 17, a comparator 55, a gate circuit 55A, a storage circuit 66, and a central processing unit ( C
PU) 57 and an arithmetic unit 64 including an arithmetic processing unit 68.

In such a configuration, the third signal processing circuit 6A
In (6B), the first ultrasonic sensor 23 is excited by the excitation section 52, and the first ultrasonic sensor 23 radiates the ultrasonic continuous wave beam 2a obliquely to the flow direction of the refrigerants 32 and 33. The first ultrasonic sensor 23 (or the second ultrasonic sensor 23A receives the scattered wave 2b) in which the ultrasonic continuous wave beam 2a is scattered by the bubbles 33 in the refrigerants 32 and 33 is received by the ultrasonic sensor 23 ( The reception frequency (f1 ± Δf2) received by the amplifier 53A is amplified by the amplifier 53A, and the output of the amplifier 53A and the frequency from the excitation unit 52 are mixed by the mixing unit 53E.
The signal of f1 is mixed and two frequencies (f1, (f1 ± Δf
2)), a high-frequency component (2f1 ± Δf2) is removed by a low-pass filter 53B to discriminate the Doppler frequency deviation ± Δf2,
53D, for example, a counter, detects the frequency Δf2, and the refrigerant 32,3
Detect the flow velocity 5f of 3.

FIG. 5 is used in combination with FIG.
The signal processing circuit 6A (6B) excites the ultrasonic sensor 25 by amplifying the power in the transmitting unit 62 by the timing pulse 61a generated at a predetermined constant interval from the timing generator 61, When an excitation signal of a rectangular wave is applied to the high-frequency vibration wave 2d having a high Q (peak value) determined by the electric / mechanical vibration system of the ultrasonic sensor 25 (see FIG. 9).
(Refer to (B)), this high-frequency vibration waveform propagates vertically through the refrigerants 32 and 33 in the refrigerant pipe 17, and the ultrasonic wave sensor 25 receives the reflected wave 2f reflected on the pipe back surface 19 of the refrigerant pipe 17. I do. This reception signal 25c is transmitted without being affected by the scattering by the bubble 33 when the bubble 33 is not generated (FIG. 8A),
When the air bubble 33 is present, the ultrasonic signal 2f scattered by the air bubble 33 and transmitted decreases, and the reception signal 25c also decreases.

The received signal 25c is amplified by the amplifier 63A, and the electric noise and the acoustic noise are removed by the band-pass filter 63B, and the amplitude of the received signal 25c is detected by the amplitude detector 63C.
6c is detected and output to the arithmetic unit 64. This received signal 25
The amplitude of c can be measured using the peak value of the received signal 25c, the integral value of the half-wave (full-wave) rectified value, or the integral value of the effective value.

Next, the operation of the arithmetic unit 54 will be described. The refrigerant leak detection device according to the third embodiment outputs an output corresponding to the flow rates of the refrigerants 32 and 33 by the third bubble flow velocity calculating means (52 to 53D) when the refrigerator is operated without refrigerant leakage prior to the start of practical operation. The relationship characteristic between 5f and the received signal level 6c by the reception level detecting means (61 to 63C) is checked in advance, and the bubble amount determination reference characteristic
This data is stored in the storage circuit 56 as (6G), and the received signal level 6c is the bubble amount determination reference value of the bubble amount determination reference characteristic (6G).
When it becomes 6 g or less, it can be determined that there is refrigerant leakage.

FIG. 7 is a characteristic diagram showing a set value of the reference bubble amount (presence / absence). In FIG. 7, the vertical axis represents the reference bubble amount, and the horizontal axis represents the output 5f corresponding to the flow rates of the refrigerants 32 and 33 by the third bubble flow velocity calculating means (52 to 53D). The operation data of the refrigerator during the operation is measured in advance, and this data is processed and stored in the storage circuit 66. In this data processing, the reception signal 25c of the ultrasonic sensor 25 with respect to the output 5f corresponding to the flow velocity of the refrigerants 32 and 33 is received and processed, and the reception signal level 6c is measured. ) Subtract the value of characteristic curve 6F and correct it.
The refrigerant 32,33 which determines the presence or absence of 33 The storage circuit 66 of the third signal processing circuits 6A, 6B of the refrigerant leak detection device of the refrigerator as a foam amount determination reference characteristic 6G using the flow rate equivalent output 5f as a parameter.
Can hold the data.

When operating as a refrigerator, the outputs 32f corresponding to the flow rates of the refrigerants 32 and 33 are calculated, and the vicinity data of the calculated data 5f is stored in the storage circuit 66 of the third signal processing circuits 6A and 6B. From, and, for example, proportionally distributed by the arithmetic processing unit 68 to determine the presence or absence of refrigerant leakage.
Is calculated, and the presence or absence of refrigerant leakage can be detected by comparing with the reception signal level 6c.

FIG. 10 shows the first to third signal processing circuits 5A, 5B, 6A, 6
The above processing program in B is shown in FIG.
The second signal processing circuits 5A and 5B are shown, and the third signal processing circuits 6A and 6B are shown in FIG. In FIG. 10A, the steps
In S1, the refrigerant is supplied from the first or second bubble flow velocity calculating means 53D.
32,33 Flow velocity equivalent output 5f is calculated. In step S2, a corresponding reference value 5d or 5e of the foam amount (presence / absence) characteristic curves 5D and 5E for judging the presence or absence of refrigerant leakage based on the data 5f is calculated, and the calculated value is compared as a target value SV. Is set as the reference value of the container 55. In step S3, the bubble generation amount calculation means 53
Read the level value PV of the received signals 5b and 5c of C, and
In S4, the corresponding calculated value SV of the calculated foam amount (presence / absence) reference values 5d and 5e is compared with the level PV of the received signals 5b and 5c, and the level PV of the received signals 5b and 5c is smaller than the calculated value SV. When it is larger (Yes), in step S5, it is output that there is a refrigerant leak. In step S4, the level PV of the received signals 5b and 5c is smaller than the calculated value SV.
If (No), the process returns to step S1 to continue monitoring.

Further, in FIG. 10B, step S11
Then, the output 5f corresponding to the flow rate of the refrigerant 32, 33 is calculated from the third bubble flow rate calculating means 53D. In step S12, the reference value of the bubble amount determination reference characteristic 6G for determining the presence or absence of refrigerant leakage based on the data 5f
6g is calculated, and the reference value 6g is set in the comparator 55 as the target value SV. In step S13, the reception level detection means (61 to
The level value PV of the received signal level 6c of (63C) is read, and in step S14, the calculated foam amount determination reference value 6g (SV) is compared with the received signal level 6c (PV), and the received signal level 6c (PV) is compared. Is smaller than the reference value 6 g (SV) (Yes), a refrigerant leak is output in step S15. When the received signal level 6c (PV) is larger (No) in step S14 than the reference value 6g (SV), the process returns to step S11 to continue monitoring.

In the refrigerant leak detecting device according to the third embodiment, since the transmitted wave of the ultrasonic signal is monitored, it is possible to perform monitoring including an abnormal state of the detecting device such that the transmitted wave itself is not detected. The present invention can be applied to a highly reliable safety system in a case where a human life is related to a crisis.

[0047]

As described above, according to the present invention, an ultrasonic sensor is installed in a refrigerant pipe from the outside, and a transmission / reception signal of the ultrasonic sensor is processed so that a sight glass is provided to the refrigerant pipe. It is possible to provide a refrigerant leak detection device that eliminates the need for processing, and to monitor the current, power, or pressure of the compressor to prevent erroneous detection during full operation of the refrigerator. The refrigerant leak detecting device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a refrigerant leak detection device for a refrigerator as one embodiment of the present invention.

FIG. 2 is a main part configuration diagram of a refrigerant leak detection device for a refrigerator as another embodiment.

FIG. 3 is a configuration diagram of a main part of a first signal processing circuit according to one embodiment;

FIG. 4 is a configuration diagram of a main part of a second signal processing circuit.

FIG. 5 is a configuration diagram of a main part of a third signal processing circuit.

FIG. 6 is a diagram illustrating the principle of one embodiment.

FIG. 7 is an explanatory diagram for explaining a bubble amount (presence / absence) characteristic curve and a bubble amount determination reference characteristic.

FIG. 8 is an explanatory diagram illustrating another principle of detecting a refrigerant leak.

FIG. 9 is a timing chart illustrating the detection principle of FIG. 8;

FIG. 10 is a flowchart for determining a refrigerant leak.

FIG. 11 is a conceptual diagram of a refrigerant leak detection sensor according to the related art.

FIG. 12 is a main part configuration diagram of a refrigerant leak detection device of a refrigerator as another embodiment.

[Explanation of symbols]

 11 Compressor 12 Condenser 13 Dryer 14 Expansion valve 15 Evaporator 16 Piping 17 High pressure side refrigerant pipe 23,23A, 25 Ultrasonic sensor 24,24A Wedge 27 Electric quantity sensor 28 Pressure sensor 22a, 22b, 22c, 25c Detection signal 2a , 2b, 2c, 2d, 2e, 2f Ultrasonic signal 31 Refrigerant (gas) 32 Refrigerant (liquid) 33 Bubbles 41 Light emitting element 42 Light receiving element 43 Sight glass 45 Display and signal processing circuit 46 Green LED 47 Red LED 52 Excitation power supply 53 , 53M, 63 Receiver 53A, 63A Amplifier 53B Low-pass filter 53C, 63C Amplitude detector 53D Frequency detector 53E Mixing unit 54, 64 Computing unit 55 Comparator 55A Gate circuit 56, 66 Storage circuit 57 Central processing unit 58, 68 Computation Processing unit 5c, 5b, 6c Received signal level 5e, 5d Reference value 5f Refrigerant flow rate 5d, 5e, 6g Reference value 5D, 5E, 6F Bubble amount (presence / absence) characteristic curve 6G Foam amount determination reference characteristic 61 Timing generator 62 Transmission Part 63B Bandpass filter

Claims (5)

[Claims] 1. A cooling device comprising a compressor, a condenser, an expansion valve, an evaporator, and a pipe connecting these devices to form a circulation system. Refrigerant that circulates through the equipment and evaporates and cools with an evaporator,
A first ultrasonic sensor which is disposed on one side of a high-pressure side refrigerant pipe connected to the evaporator and emits an ultrasonic continuous wave beam obliquely with respect to the flow direction of the refrigerant; A first signal processing circuit that continuously excites the sensor, receives a scattered wave in which an ultrasonic continuous wave beam of the first ultrasonic sensor is scattered by bubbles in the refrigerant, and processes the received signal; The first signal processing circuit comprises: a first bubble sensor that calculates a refrigerant flow velocity from a shift frequency signal of a transmission frequency transmitted by the first ultrasonic sensor, a reception frequency of the first ultrasonic sensor, A first bubble generation amount calculating means for calculating a bubble generation amount in the refrigerant from the amplitude of the shift frequency signal, and a calculation for calculating a reference value from a bubble amount (presence / absence) characteristic curve based on data of the first bubble flow velocity calculating means. Data of the processing unit and the first bubble generation amount calculating means Comparing means for comparing with a reference value, wherein it is determined that there is a refrigerant leak when the data of the first bubble generation amount calculating means is larger than the reference value of the bubble amount (presence / absence) characteristic curve. Detection device. 2. A cooling system comprising a compressor, a condenser, an expansion valve, an evaporator, and a pipe connecting these devices to form a circulation system. Refrigerant that circulates through the equipment and evaporates and cools with an evaporator,
A first ultrasonic sensor, which is disposed obliquely on one side of a high-pressure refrigerant pipe connected to the evaporator and emits a continuous ultrasonic wave beam obliquely with respect to the flow direction of the refrigerant, and a first ultrasonic sensor A second ultrasonic sensor that receives a scattered wave of the ultrasonic continuous wave beam scattered by bubbles in the refrigerant and a first ultrasonic sensor that are continuously excited to process a received signal received by the second ultrasonic sensor A second signal processing circuit, the second signal processing circuit comprising: a transmission frequency transmitted by the first ultrasonic sensor; a reception frequency received by the second ultrasonic sensor;
A second bubble flow rate calculating means for calculating the flow velocity of the refrigerant from the shift frequency signal, a second bubble generation amount calculating means for determining the amount of bubbles generated in the refrigerant from the amplitude of the shift frequency signal,
An arithmetic processing unit for calculating a reference value from a bubble amount (presence / absence) characteristic curve based on data of the bubble flow rate calculating means; and a comparing means for comparing data of the second bubble generation amount calculating means with the reference value; A refrigerant leakage detecting device, wherein when the data of the second bubble generation amount calculating means is larger than a reference value of a bubble amount (presence / absence) characteristic curve, it is determined that there is refrigerant leakage. 3. The refrigerant leakage detecting device according to claim 1, wherein the third ultrasonic sensor is vertically arranged on one side surface of another high pressure side refrigerant pipe connected to the evaporator. And the first or second
In place of the signal processing circuit, the first ultrasonic sensor is continuously excited, and the ultrasonic signal is received by the first ultrasonic sensor or the second ultrasonic sensor to receive a scattered wave scattered by bubbles in the refrigerant. A third signal processing circuit for performing processing, the third signal processing circuit comprising: a third bubble flow velocity calculating means for determining a passage velocity of the refrigerant from a shift frequency signal between the transmission frequency and the reception frequency; and a third ultrasonic sensor. And a receiving level detecting means for receiving a reflected wave returning to the ultrasonic sensor and detecting the amplitude of the third received signal, and a bubble amount determination reference value based on data of the third bubble flow rate calculating means. A third arithmetic processing unit for calculating, and comparing means for comparing data of the reception level detection means with a reference value of the third arithmetic processing unit, wherein the data of the reception level detection means is lower than the bubble amount determination reference value. Determined that there is a refrigerant leak That refrigerant leakage detection device, characterized in that. 4. The refrigerant leak detection device according to claim 1, further comprising an electric quantity sensor for detecting current consumption or power consumption of the compressor, and an arithmetic processing unit of the first or second signal processing circuit. Calculates a reference value from a bubble amount (presence / absence) characteristic curve based on current consumption or power consumption data instead of the data obtained by the first or second bubble flow rate calculation means, and calculates the first or second bubble generation amount. A refrigerant leakage detection device, wherein it is determined that there is refrigerant leakage when the data of the calculating means is larger than the reference value of the bubble amount (presence / absence) characteristic curve. 5. The refrigerant leak detecting device according to claim 1, further comprising a pressure sensor for measuring a refrigerant pressure at a compressor or at an outlet refrigerant pipe of the compressor, wherein the first or second signal processing circuit is provided. The arithmetic processing unit calculates a reference value from a bubble amount (presence / absence) characteristic curve based on the data of the pressure sensor instead of the data obtained by the first or second bubble flow rate calculating means, and calculates the first or second bubble. A refrigerant leakage detection device, wherein it is determined that there is refrigerant leakage when data of the generation amount calculation means is larger than a reference value of a bubble amount (presence / absence) characteristic curve.