JP2006078090A - Refrigeration unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigeration unit capable of surely detecting leak of refrigerant and alarming it to a user, a manager or the like. <P>SOLUTION: This refrigeration unit comprises a refrigerant circulating passage 6 having a compressor 8, a condenser 12, an expansion valve 16 and an evaporator 18 interposed in this order. The circulating passage 6 has a liquid flow area of liquid refrigerant from the condenser 12 to the expansion valve 16 and a gas flow area of mainly gas refrigerant from the evaporator 18 to the compressor 8. The refrigeration unit further comprises a detector 24 detecting the presence of gas refrigerant in the liquid flow area. The detector 24 lights an alarm lamp 30 displaying leak of refrigerant, upon detecting the gas refrigerant. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigeration circuit, and more particularly to a refrigeration circuit for a vehicle air conditioning system suitable for use with a flammable refrigerant having a low global warming potential.

In recent years, development of an air conditioning system in consideration of the global environment has been promoted, and this air conditioning system includes a refrigeration circuit using a refrigerant having a low global warming potential. Specifically, examples of this type of refrigerant include new alternative chlorofluorocarbon gas such as R152a or HC gas such as propane.
Since these gases are flammable, this type of air conditioning system, particularly a vehicle air conditioning system, includes a gas sensor that detects a leaked refrigerant in order to ensure safety (see, for example, Patent Document 1). ).
JP-A-9-104221

However, when the gas sensor is used, even if the refrigerant leaks, if the gas concentration does not increase in the vicinity of the gas sensor, it is impossible to detect the refrigerant leak, and there is a risk of missing the refrigerant leak. .
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a refrigeration apparatus that can reliably detect leakage of refrigerant and warn a user, a manager, or the like. There is.

In order to achieve the above-described object, the refrigeration apparatus of the present invention includes a compressor, a condenser, an expansion valve, and an evaporator interposed in this order, and a liquid refrigerant flow area from the condenser to the expansion valve, and A refrigerant circulation passage mainly having a gas flow area of gas refrigerant from the evaporator to the compressor, and a detector arranged in the liquid flow area, and detecting means for detecting the presence of the gas refrigerant in the liquid flow area; And a warning means for outputting a detection result when the detection means detects a gas refrigerant (claim 1). Specifically, the detector comprises a self-heating type thermistor (Claim 3), or a pair of a light emitting element and a light receiving element (Claim 4). The warning means includes a warning light (claim 5).
According to the configuration described above, when the gas refrigerant is present in the liquid circulation area where the liquid refrigerant should flow in the refrigerant circulation flow path and this presence is detected by the detector, the detection means leaks the refrigerant into the refrigerant circulation flow path. Is determined to have occurred. That is, if the refrigerant leaks from any part of the refrigerant circulation channel, the amount of refrigerant in the refrigerant circulation channel decreases, and gas refrigerant is generated in the liquid flow region. It becomes an index representing the presence or absence of refrigerant leakage. Therefore, since the detecting means detects the leakage of the refrigerant through the detector, the warning means detects the refrigerant leakage to the user or manager of the refrigeration apparatus based on the detection result of the detecting means. Make sure you are warned.

As a preferred aspect, a receiver is further inserted in the liquid flow area, and the detector is disposed downstream of the receiver. In this case, when the refrigeration apparatus is operating normally, there is no gas refrigerant in the liquid flow area downstream from the receiver. However, since the gas refrigerant is also generated in the liquid flow area when the refrigerant leaks, the detector does not erroneously detect the refrigerant leak.
As a preferred aspect, the refrigerant is composed of a combustible refrigerant. This is because flammable refrigerants generally have a low global warming potential and are friendly to the global environment.

  As a preferred aspect, the refrigerant circulation passage is arranged from the engine room to the vehicle compartment of the vehicle (Claim 7). In the unlikely event that the refrigerant leaks and the vehicle is operated without noticing it, the engine or the like may ignite as a heat source. However, according to the above configuration, the occupant is reliably warned of the refrigerant leak. Therefore, the safety of passengers is ensured.

  As described above, according to the refrigeration apparatus of claims 1 to 7, the refrigerant leakage can be reliably detected by the detection means. For this reason, even if the refrigeration apparatus using the combustible refrigerant is applied to the vehicle air conditioning system, the safety of the passenger is ensured (claims 6 and 7).

FIG. 1 shows a schematic configuration of a refrigeration apparatus according to an embodiment applied to a vehicle air conditioning system.
The refrigeration apparatus includes a circulation flow path 6 that extends from the engine room 2 of the vehicle to the vehicle compartment 4 via the dash panel 3 and is filled with R152a as a refrigerant. A compressor 8 is inserted in the circulation flow path 6 in the engine room 2, and the compressor 8 is operated by the driving force of the engine 10. The compressor 8 sucks and compresses the low-pressure gas refrigerant from the circulation channel 6 and discharges the high-temperature and high-pressure gas refrigerant to the circulation channel 6 again. That is, the compressor 8 generates a refrigerant flow while compressing the refrigerant.

A condenser 12 is inserted into the circulation channel 6 on the downstream side of the compressor 8 in the refrigerant flow direction. The condenser 12 blows air from the front of the vehicle and blower fan (not shown). In response, the refrigerant flowing inside is cooled by air and condensed.
In addition, a receiver 14 is inserted downstream of the condenser 12 in the circulation channel 6, and the receiver 14 separates undesired gas refrigerant remaining in the high-pressure liquid refrigerant flowing from the condenser 12. Only the liquid refrigerant is allowed to flow downstream.

  Further, an expansion valve 16 and an evaporator 18 are inserted in the circulation flow path 6 on the downstream side of the receiver 14 in this order, and the evaporator 18 is disposed in the vehicle compartment 4. Specifically, an air conditioning unit housing (not shown) is disposed in the instrument panel 20 in front of the passenger compartment 4, and in this air conditioning unit housing, an evaporator 18, a heater core, and an air conditioning unit of the air conditioning system are provided. A blower fan (not shown) is accommodated together. The high-pressure liquid refrigerant from the receiver 14 is supplied to the evaporator 18 through the expansion valve 16 and is vaporized in the evaporator 18 to become a low-temperature and low-pressure gas refrigerant. The downstream side of the evaporator 18 is connected to the compressor 8, and the gas refrigerant is sucked into the compressor 8. The valve opening of the expansion valve 16 is automatically varied according to the refrigerant temperature on the downstream side of the evaporator 18, and adjusts the degree of superheat of the refrigerant on the downstream side of the evaporator 18.

In the circulation flow path 6, the compressor 8, the condenser 12, the receiver 14, the expansion valve 16 and the evaporator 18 are connected by a pipe line 22.
The refrigeration apparatus is a self-heating type that is liquid-tightly attached to a pipe line 22 that connects between the receiver 14 and the expansion valve 16 as a detector 24 for detecting refrigerant leakage from the circulation flow path 6. The thermistor 26 has a thermistor 26, and the heating resistor portion of the thermistor 26 projects into the pipe line 22. The thermistor 26 is electrically connected to a control circuit 28 in the instrument panel 20, and the control circuit 28 supplies power to the thermistor 26 to generate heat at a predetermined heat generation amount, and the electric resistance of the thermistor 26. Can be detected.

The control circuit 28 is also electrically connected to a warning lamp 30 provided on the instrument panel 20. When the electrical resistance of the thermistor 26 falls below a predetermined lower limit value, the control circuit 28 energizes the warning lamp 30. To light up.
In the vehicle air conditioning system having the above-described configuration, the interior of the passenger compartment 4 is cooled by circulating the refrigerant in the circulation passage 6 during the normal cooling operation. More specifically, during operation of the compressor 8, the high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 8 becomes high-pressure liquid refrigerant through the condenser 12, and then sent to the expansion valve 16 through the receiver 14. It is done. The expansion valve 16 ejects liquid refrigerant into the evaporator 18 at a predetermined valve opening to vaporize the refrigerant so that the degree of superheat of the refrigerant at the outlet of the evaporator 18 becomes a predetermined value. The vaporized gas refrigerant is sucked into the compressor 8 and sent to the condenser 12 again. When the air blower of the air conditioning unit described above is activated in the circulation process of the refrigerant, the cool air that has passed through the evaporator 18 and has lost the heat of vaporization is supplied into the vehicle interior 4. Cool to desired set temperature.

The vehicle air conditioning system having the above-described configuration uses R152a having a small global warming potential as a refrigerant, and is friendly to the global environment.
Moreover, even if the refrigerant | coolant leaks from any location of the circulation flow path 6, the vehicle air conditioning system of the above-described structure lights the warning lamp 30 and reliably warns the passenger of the refrigerant leakage. Therefore, even if R152a, which is a flammable refrigerant, leaks from the circulation flow path 6, the occupant can surely notice the refrigerant leakage and deal with it, so that the situation where the engine 10 or the like is ignited as a heat source is surely avoided. And the safety of passengers is ensured.

  More specifically, in the above-described refrigerant circulation process, a portion of the circulation flow path 6 extending from the condenser 12 to the expansion valve 18 forms a liquid flow region in which a high-pressure liquid refrigerant flows. The state of the refrigerant flowing in this liquid flow area is indicated by a point A on the Mollier chart shown by a two-dot chain line in FIG. 3, and the point A is in the supercooled liquid area on the left side of the saturated liquid line. Moreover, the part from the evaporator 18 to the compressor 8 among the circulation flow paths 6 forms the gas flow area through which the low-pressure gas refrigerant flows.

  On the other hand, when the refrigerant leaks from any part of the circulation flow path 6 and the amount of the refrigerant in the circulation flow path 6 decreases, the refrigerant pressure decreases in the liquid flow area and rises in the gas flow area. The diagram is as shown by the solid line in FIG. And the state of the refrigerant | coolant which flows through a liquid flow area is shown by the point B on the same figure, and the point B exists in the two-phase area which exists between a saturated liquid line and a saturated vapor line. Therefore, when the amount of the refrigerant in the circulation flow path 6 decreases, the gas refrigerant is included in the refrigerant in the liquid flow area of the circulation flow path 6 where the liquid refrigerant should flow. That is, the presence / absence of the gas refrigerant in the liquid flow region is an indicator of the presence / absence of refrigerant leakage from the circulation flow path 6.

On the other hand, in the detector 24 attached to the liquid flow area of the circulation flow path 6, that is, the self-heating type thermistor 26, the heating resistance portion receives heat supply from the control circuit 28 and generates heat with a constant heating value. However, heat is taken away by the surrounding refrigerant.
Here, Table 1 shows the thermal conductivity of liquid-phase and gas-phase R152a at a temperature of 25 ° C.

表１に示したように、液相のＲ１５２ａは気相のＲ１５２ａに比べ約１０倍近く大きな熱伝導率を有している。このため、循環流路６中の冷媒量が減少して液流域にガス冷媒が混在するようになると、サーミスタ２６の発熱抵抗部から奪われる熱量が低下し、発熱抵抗部の温度が上昇する。この発熱抵抗部の温度上昇は、図４に模式的に示したように、サーミスタ２６の電気抵抗低下をもたらす。つまり、サーミスタ２６は、（過熱ガス域のガス冷媒によって発熱抵抗部から奪われる熱量）＜（発熱抵抗部の発熱量）＜（過冷却液域の液冷媒によって発熱抵抗部から奪われる熱量）となるようにＢ定数及びＣ定数が設定されている。

As shown in Table 1, the liquid phase R152a has a thermal conductivity nearly 10 times greater than that of the gas phase R152a. For this reason, when the amount of refrigerant in the circulation channel 6 decreases and gas refrigerant is mixed in the liquid flow region, the amount of heat taken away from the heat generating resistor portion of the thermistor 26 decreases, and the temperature of the heat generating resistor portion increases. This temperature rise of the heat generating resistor part causes a decrease in the electrical resistance of the thermistor 26, as schematically shown in FIG. That is, the thermistor 26 has the following formula: (amount of heat taken away from the heating resistor portion by the gas refrigerant in the superheated gas region) <(amount of heat generated from the heating resistor portion) <(amount of heat taken away from the heating resistor portion by the liquid refrigerant in the supercooled liquid region). The B constant and the C constant are set so that

  The electrical resistance of the thermistor 26 is measured and monitored by the control circuit 28. The control circuit 28 determines that the refrigerant state changes from the supercooled liquid region to the two-phase region when the electrical resistance of the thermistor 26 becomes smaller than a predetermined lower limit value. Judged to have changed. The determination that the state has changed to the two-phase region, that is, the determination that the gas refrigerant is present in the liquid flow region and the refrigerant leakage has occurred, and the control circuit 28 is based on the determination result of the refrigerant leakage occurrence, The warning lamp 30 is energized and lit to warn the occupant of refrigerant leakage.

The present invention is not limited to the one embodiment described above, and various modifications are possible.
In one embodiment, the receiver 14 is inserted between the condenser 12 and the expansion valve 16, but instead of the receiver 14, an accumulator is inserted between the evaporator 18 and the compressor 8 to expand the expansion valve. A fixed aperture may be used as 18. In this case, the gas refrigerant mainly flows in the gas flow region between the evaporator 18 and the accumulator, but the liquid refrigerant may also flow slightly. However, if the gas refrigerant that has not been accidentally condensed in the condenser 12 flows through the liquid flow area of the circulation flow path 6, it will lead to malfunction of the detector 24, and the detection accuracy of refrigerant leakage will be reduced. For this reason, it is preferable to arrange the detector 24 downstream of the receiver 14 as in the embodiment.

In one embodiment, R152a is used as the refrigerant, but other chlorofluorocarbon gas (HFC gas) or HC gas such as propane gas may be used.
In one embodiment, the warning light 30 is used as a warning means for the occupant, but a warning buzzer may be used instead of the warning light 30 or together with the warning light 30.
In one embodiment, the thermistor 26 is used as the detector 24 for detecting the gas refrigerant in the liquid flow region in the circulation flow path 6. However, as shown in FIG. 5, the light emitting element 32 and the light from the light emitting element 32 are used. An optical detector 24 including a light receiving element 34 capable of receiving light may be used. The light emitting element 32 and the light receiving element 34 are arranged on both sides of the pipe line 22 through the transparent glass plate 36, and the light emitted from the light emitting element 32 passes through the liquid refrigerant in the glass plate 36 and the pipe line 22. , Enters the light receiving element 34. When light passes through the liquid refrigerant, if bubbles of the gas refrigerant are included in the liquid refrigerant, the light is scattered by the bubbles, and the intensity of incident light to the light receiving element is attenuated. Therefore, the control circuit 28 detects the attenuation of the incident light intensity to the light receiving element 34, and turns on the warning lamp 30 when the attenuation reaches a certain level. A microphone can also be used as the detector 24. In this case, the presence of the gas refrigerant in the liquid refrigerant is detected by detecting abnormal noise generated when bubbles of the gas refrigerant are ejected from the expansion valve 16. Is detected. Note that when a pressure sensor is used as the detector 24, the pressure drop in the circulation flow path 6 is small until the refrigerant almost disappears from the circulation flow path 6, and it is difficult to detect refrigerant leakage at an early stage. For this reason, the thermistor 26 is preferably used as the detector 24 as in the embodiment.

  Finally, it goes without saying that the refrigeration apparatus of the present invention can be applied not only to an air conditioning system for a vehicle but also to a room air conditioner, a refrigerator, and a freezer.

It is the figure which showed schematic structure of the freezing apparatus of one Example applied to the vehicle air conditioning system. It is sectional drawing of the detector in the refrigeration apparatus of FIG. FIG. 2 is a Mollier chart for explaining generation of gas refrigerant at the time of refrigerant leakage in the liquid flow region of the circulation channel in the refrigeration apparatus of FIG. 1. It is a graph which shows the relationship between the temperature and electrical resistance in the thermistor of FIG. It is the figure which showed the modification of the detector of FIG.

Explanation of symbols

6 Circulating Channel 8 Compressor 12 Condenser 16 Expansion Valve 18 Evaporator 24 Detector 30 Warning Light

Claims (7)

A compressor, a condenser, an expansion valve and an evaporator are inserted in this order, and a liquid refrigerant liquid flow area from the condenser to the expansion valve and a gas refrigerant gas flow area mainly from the evaporator to the compressor are provided. A refrigerant circulation channel having,
A detector disposed in the liquid flow region, and detecting means for detecting the presence of a gas refrigerant in the liquid flow region;
A refrigeration apparatus comprising: a warning unit that outputs a detection result when the detection unit detects a gas refrigerant. A receiver is further inserted in the liquid flow area,
The refrigeration apparatus according to claim 1, wherein the detector is disposed downstream of the receiver.   3. The refrigeration apparatus according to claim 1, wherein the detector is a self-heating type thermistor.   The refrigeration apparatus according to claim 1, wherein the detector includes a pair of a light emitting element and a light receiving element.   The refrigeration apparatus according to claim 1, wherein the warning unit includes a warning light.   The refrigeration apparatus according to claim 1, wherein the refrigerant is made of a flammable refrigerant.   The refrigeration apparatus according to any one of claims 1 to 6, wherein the refrigerant circulation passage is arranged from an engine room to a vehicle compartment of a vehicle.

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