JP2009092268A - Refrigerant leakage detecting method of refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerant leakage detecting method for detecting the leakage of a refrigerant on the basis of a refrigerant temperature in the front or rear of an evaporator, capable of keeping a detecting capacity of a refrigerant leakage detecting system in the best condition and reducing costs of a refrigerant leakage detecting device even when the method is applied to freezing, refrigerating and air-conditioning equipment with which a plurality of evaporators are connected, and to provide a refrigerant leakage detecting method of the freezing, refrigerating and air-conditioning equipment capable of preventing wrong detection of refrigerant leakage after restarting flowing in/out of the refrigerant to the evaporator, in a case when the flowing of the refrigerant is stopped even under such a condition that the refrigerant should flow in/out to the evaporator. <P>SOLUTION: A sensor for detecting a temperature of the refrigerant is mounted only a terminal end of a refrigerant pipe or an evaporator which the refrigerant hardly reaches. Further in this refrigerant leakage detecting method for the freezing, refrigerating and air conditioning equipment, the refrigerant amount is not determined until a prescribed time has passed after restarting the flowing in/out of the refrigerant to the evaporator or a solenoid valve has been operated by the prescribed number of times, when the flow of the refrigerant is stopped even under such a condition that the refrigerant should flow in/out to/from the evaporator. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a monitoring device for a refrigeration apparatus that detects a shortage of refrigerant amount in a refrigerant circuit.

  FIG. 2 is a refrigerant circuit diagram of a general refrigeration apparatus. Compressor 25, oil separator 28 (also referred to as oil separator), condenser 29 (also referred to as condenser), receiver tank 39 (also referred to as receiver), first pipe joint 24a, solenoid valve 27, expansion valve 38, an evaporator (also referred to as a cooler or an evaporator) 20, a second pipe joint 24b, a liquid separator 37 (also referred to as an accumulator), etc. are connected by a refrigerant pipe, and the first pipe joint 24a A refrigerant path connected in series to the solenoid valve 27, the expansion valve 38, and the evaporator 20 between the second pipe joints 24b is provided alone or in parallel (in FIG. 2, four systems in parallel), and a showcase is provided. 23 refrigerant circuits 24 are formed.

  For example, when the refrigerant leaks from the refrigerant circuit 24 of the refrigeration apparatus, the object to be frozen cannot be lowered to the target temperature. In the case of a frozen showcase 23 used in a store or the like, an object that is to be frozen, that is, a warehouse in which, for example, ice cream melts because the temperature in the warehouse of the showcase 23 does not reach the target temperature. An abnormal internal temperature is detected. The cause of the failure in which the internal temperature of the showcase 23 does not reach the target is due to the seizure of the compressor 25, the disconnection of the coil of the solenoid valve 27, and a plurality of other than the leakage of the refrigerant. It is impossible to identify refrigerant leakage from Further, at the time when the inside temperature of the showcase 23 does not reach the target temperature due to the leakage of the refrigerant, the refrigerant in the refrigerant circuit 24 is almost leaked. At the same time, since the internal temperature does not reach the target, the quality of the product in the showcase 23 is also deteriorated. In addition, the repair requires specialist engineers and tools, which takes time and effort, and it takes a considerable number of days before the showcase 23 can be used.

  As a countermeasure, it is conceivable to adopt a method of specifying and detecting only the refrigerant leakage. Then, as a conventional method for detecting refrigerant leakage from the refrigerant circuit 24, an evaporator 20 (both a cooler or an evaporator) is used to prevent the compressor 25 from being damaged due to an insufficient amount of refrigerant in the cooling device (automobile cooling device). The first detection member that detects the refrigerant temperature at the inlet 21 and the second detection member that detects the refrigerant temperature at the evaporator outlet 22 operate when a difference of a predetermined value or more occurs. Some of them are provided with a refrigerant shortage detection switch for a cooling device characterized by having a contact. As another example, a thermistor is provided with a temperature response control device that has a refrigerant amount shortage detection function and detects a cooling control temperature and generates an on / off control signal. In some cases, a detection signal is output when the difference between the outputs of the thermistors exceeds a predetermined value. In addition, the following patent documents 1-2 can be mentioned as a well-known technique relevant to this invention as mentioned above.

Japanese Utility Model Publication No. 55-023169 Japanese Utility Model Publication No. 56-118365

  As described above, in one technique of the related art (Patent Document 1), it is necessary to attach a sensor so that the refrigerant temperature detection member is in contact with the refrigerant. And since this technique presupposes the cooling device of a motor vehicle, the case where the refrigerant path to which an evaporator is connected is fundamentally one is assumed. FIG. 2 is a refrigerant circuit diagram of the refrigeration apparatus. In this case, four refrigerant paths are provided. When this refrigerant quantity shortage detection device is applied to the four refrigerant paths as shown in FIG. 2, the refrigerant quantity shortage detection device is attached to the inlet 21 and the evaporator outlet 22 of the evaporator 20 (also referred to as a cooler or an evaporator). This is a difficult operation because it is necessary to perform the piping processing for the four routes (the temperature sensor is in direct contact with the refrigerant at the inlet and outlet portions of the evaporator). Thus, when a plurality of evaporators 20 are connected to the refrigerator 26, it becomes very difficult in terms of cost and work.

  FIG. 3 includes an evaporator inlet (21 in FIG. 2) and an evaporator outlet (FIG. 2), including a state 30 in which the solenoid valve (27 in FIG. 2) upstream of the evaporator is closed in a closed state for defrosting the evaporator. It is a figure which shows the change of the refrigerant | coolant temperature difference of 2 of 22). In addition, the refrigerant is gradually removed from the refrigerant circuit with the passage of time in a portion other than the state 30 in which the electromagnetic valve is stopped in the closed state, and the pseudo refrigerant leakage is reproduced. In the defrosting period 30, the open / close signal 33 of the solenoid valve indicates a closed state, and the temperature 32 in the showcase cabinet is rising. From FIG. 3, the temperature difference 31 between the evaporator inlet (21 in FIG. 2) and the outlet (22 in FIG. 2) is the condition that the refrigerant flow resumed (defrosting was completed, the solenoid valve was opened, and the refrigerant began to flow again. It can be seen that almost the same state is shown under the condition (state) 34 and the condition 35 where the refrigerant has escaped. In the other technique of Patent Document 2, the thermistor detects the refrigerant temperature at the inlet (21 in FIG. 2) and the outlet (22 in FIG. 2) of the evaporator regardless of whether the refrigerant is flowing or not. When the difference between the outputs becomes equal to or greater than a predetermined value, a detection signal indicating that the refrigerant amount is insufficient is output. However, even if the amount of refrigerant in the refrigeration cycle is constant, after the temperature of the cooling target rises as described above and the refrigerant flow is forcibly stopped when the refrigerant should flow into the evaporator, Since the temperature difference between the inlet and the outlet of the evaporator becomes large, the technique of (Patent Document 2) alone causes an erroneous determination of the refrigerant amount.

  In order to apply one of the above-described prior arts to a refrigeration facility in which a plurality of evaporators are connected to a refrigerator, the amount of work increases and costs increase, and a misjudgment occurs only with the other method. There are potential conditions and the risk to economic loss is great.

  The present invention has been made in view of such a point, and the object thereof is light and cost-effective even when a plurality of evaporators are connected to a refrigerator. Providing a refrigerant leak detection method for refrigeration equipment that can improve detection performance, and providing a robust refrigerant leak detection method that does not cause erroneous determination due to changes in operating conditions and environmental conditions of the refrigeration equipment There is to do.

  The present invention that achieves the above object is provided by (1) to (3).

  (1) Like the refrigeration apparatus A shown in FIG. 1, a compressor 1 (also referred to as a compressor), an oil separator 2 (also referred to as an oil separator), a condenser 3 (also referred to as a condenser), and a receiver tank 4 ( Also called a liquid receiver), a first pipe joint 5 (also called a pipe joint or pipe fitting), a solenoid valve 6, an expansion valve 7, an evaporator 8 (also called a cooler or an evaporator), a second pipe. The joint 9 (also referred to as a pipe joint or pipe fitting), a liquid separator 10 (also referred to as an accumulator), and the like are connected by a refrigerant pipe 11, and the outlet side of the receiver tank 4 (liquid receiver); Between the inlet side of the liquid separator 10 (accumulator), a refrigerant path in which the solenoid valve 6, the expansion valve 7, and the evaporator 8 are connected in series using the refrigerant pipe 11 is connected to the refrigerant pipe 11. Between the first pipe joint 5 connected to the outlet side of the receiver tank 4 and the second pipe joint 9 connected to the inlet side of the liquid separator 10 via the refrigerant pipe 11. In the refrigerant circuit of the refrigerating apparatus A having a refrigerant path provided alone or in parallel (one system in the embodiment of FIG. 1 and eight systems in FIG. 4), the expansion valve 7 and the evaporator 8 Electricity of each of the second temperature sensor 13 provided between the first temperature sensor 12 provided between the inlet side 17 and the outlet side 16 of the evaporator 8 and the second pipe joint 9 is provided. A signal is input to the calculator 15 through the electrical signal line 14 and the refrigerant amount in the refrigerant circuit of the refrigeration apparatus A is determined based on the refrigerant at the evaporator outlet 16 and / or the evaporator inlet 17 or the temperature corresponding to the refrigerant. In the refrigerant leak detection method for the refrigeration apparatus A, the first temperature sensor Sa 12 and the second temperature sensor 13 is to mount the temperature sensitivity of the relative refrigerant leakage is high evaporator 8 only (evaporator 8 having the following overall number) in the refrigerant circuit, to solve the above problems.

  An example of an evaporator having high temperature sensitivity to refrigerant leakage in the refrigerant circuit is shown. When a plurality of showcases (eight in this figure) are connected to one refrigerator 45 as shown in FIG. 4, a set 41 of showcases separated from the refrigerator 45 and having a long refrigerant pipe 44. Further, in the evaporator 49 of the showcase 43 at the end, partial gasification occurs due to a rise in the temperature of the refrigerant, so that the refrigerant supply amount is smaller than that of other showcase evaporators. 4, the refrigerant pipe 44 is not separated from the refrigerator 45, but the refrigerant pipe connection to the showcase 46 located in the middle is located above the refrigerant pipe 44. Since the refrigerant gas existing above the refrigerant pipe 44 is easily sucked, the amount of refrigerant supplied is smaller than that of other showcase evaporators. When the amount of refrigerant decreases, changes in the outlet side refrigerant temperature of these evaporators and changes in the difference between the inlet side refrigerant temperature and the outlet side refrigerant temperature under conditions where a sufficient amount of refrigerant is difficult to reach Larger than the evaporator. Therefore, these evaporators are more sensitive to the decrease in the amount of refrigerant in the refrigerant circuit due to refrigerant leakage, evaporators in which changes in the outlet temperature of the evaporator and the temperature difference between the inlet temperature and the outlet temperature occur, that is, refrigerant leakage. It can be said that the evaporator is highly sensitive to temperature.

  (2) is also a compressor 1, an oil separator 2, a condenser 3, a receiver tank 4, a first pipe joint 5, an electromagnetic valve 6, an expansion valve 7, and evaporation as in the refrigeration apparatus A shown in FIG. 1. Between the condenser 8, the second pipe joint 9, the liquid separator 10, and the like by the refrigerant pipe 11, and between the outlet side of the receiver tank 4 and the inlet side of the liquid separator 10. A first pipe connected to the outlet side of the receiver tank 4 via a refrigerant pipe 11 through a refrigerant path in which the valve 6, the expansion valve 7 and the evaporator 8 are connected in series using the refrigerant pipe 11. Between the joint 5 and the second pipe joint 9 connected to the inlet side of the liquid separator 10 via the refrigerant pipe 11, a plurality of them (single system in the embodiment of FIG. 1). In FIG. 4, in the refrigerant circuit of the refrigeration apparatus A having eight refrigerant paths, the expansion valve 7 and the evaporator 8 are provided. Electrical signals of the first temperature sensor 12 provided between the inlet side 17 and the second temperature sensor 13 provided between the outlet side 16 of the evaporator and the second pipe joint 9. Is input to the calculator 15 through the electric signal line 14, and the refrigerant quantity of the refrigeration apparatus A is determined based on the refrigerant at the evaporator outlet 16 and / or the evaporator inlet 17 or the temperature corresponding to the refrigerant. In the refrigerant leak detection method of the apparatus A, when the flow of the refrigerant is stopped even if the refrigerant should flow into and out of the evaporator 8 in order to reach the temperature to be cooled to the target value, to the evaporator 8 The above problem is solved by not determining the refrigerant amount until a predetermined time has elapsed after resuming the refrigerant inflow / outflow, or not performing the abnormality determination based on the refrigerant amount determination result.

  (3) is also a compressor 1, an oil separator 2, a condenser 3, a receiver tank 4, a first pipe joint 5, an electromagnetic valve 6, an expansion valve 7, and evaporation as in the refrigeration apparatus A shown in FIG. 1. Between the condenser 8, the second pipe joint 9, the liquid separator 10, and the like by the refrigerant pipe 11, and between the outlet side of the receiver tank 4 and the inlet side of the liquid separator 10. A first pipe joint in which a refrigerant path in which the valve 6, the expansion valve 7, and the evaporator 8 are connected in series using a refrigerant pipe 11 is connected to the outlet side of the receiver tank 4 through a refrigerant pipe. 5 and a second pipe joint connected to the inlet side of the liquid separator 10 via a refrigerant pipe 11 singly or in parallel (in the embodiment of FIG. 4 is parallel to 8 systems) in the refrigerant circuit of the refrigerating apparatus A having the refrigerant path provided, and the inlet of the expansion valve 7 and the evaporator 8 The first temperature sensor 12 provided between the second temperature sensor 13 and the second temperature sensor 13 provided between the outlet side 16 of the evaporator and the second fitting 9 is electrically connected. The refrigerant quantity of the refrigeration apparatus A is determined by the temperature corresponding to the refrigerant or the refrigerant at the evaporator outlet 16 and / or the evaporator inlet 17 by inputting to the calculator 15 through the target signal line 14. In this refrigerant leak detection method, if the refrigerant flow is stopped even if the refrigerant should flow into and out of the evaporator 8 in order to make the temperature to be cooled reach the target value, the refrigerant to the evaporator 8 is stopped. The above problem is solved by not determining the refrigerant amount until the solenoid valve 6 operates a predetermined number of times after resuming the inflow / outflow of the refrigerant, or not performing the abnormality determination based on the determination result of the refrigerant amount. .

  As described above, according to the present invention, even when the refrigerant leak detection method is applied to a refrigeration facility in which a plurality of evaporators are connected to a refrigerator, the present invention can be easily and inexpensively implemented. Furthermore, since the refrigerant leakage is detected based on the change in the characteristics of the evaporator having high sensitivity regarding refrigerant leakage (leakage), the detection sensitivity becomes high, and early refrigerant leakage detection becomes possible. In addition, it is possible to provide a highly reliable refrigerant leak detection function that does not cause erroneous determination even under non-normal conditions that block the refrigerant flow regardless of the cooling conditions.

[Effect of the first embodiment]
(Related to claim 1)
In FIG. 1, there is one showcase to be cooled connected to one refrigerator, but in FIG. 4, a plurality of showcases to be cooled (8 in this figure) are connected. FIG. In the right showcase set 41 in FIG. 4, the refrigerant pipe 44 is long and away from the refrigerator 45. Among them, in the showcase 43 at the end, partial gasification occurs due to the temperature rise of the refrigerant, so that the refrigerant supply amount becomes smaller than other showcases. Further, in the left showcase set 42 in FIG. 4, the refrigerant pipe 44 is not separated from the refrigerator 45, but the refrigerant pipe 44 is connected to the evaporator 49 of the showcase 46 located in the middle. In this case, the refrigerant is taken out from above the pipe. Also in this case, since the gas existing above the refrigerant pipe 44 is easily sucked, the supply amount of the refrigerant is reduced as compared with other showcases. In addition, as a condition for reducing the amount of refrigerant supplied to the showcase, a case where the inclination of the refrigerant pipe 44 increases toward the end of the refrigerant pipe 44 can be considered. FIG. 7 shows a temperature difference 71 between the evaporator outlet and the inlet refrigerant in the showcase located near the refrigerator 45 when the refrigerant leaks from the refrigeration apparatus, that is, the first temperature sensor (47 in FIG. 4). This is the output difference of the second temperature sensor (48 in FIG. 4). FIG. 8 is actual measurement data of the temperature difference 81 between the refrigerant outlet and inlet refrigerant in the showcase at the end of the refrigerant pipe 44 located away from the refrigerator 45 when refrigerant leakage occurs from the refrigeration apparatus. 7 and 8 both take out the refrigerant from the refrigerant pipe 44 from the side surface of the pipe, and are under the same conditions. The refrigerator 45 is also the same, and the data is acquired at the same timing. The refrigerant leakage is a reproduction of pseudo refrigerant leakage by gradually removing the refrigerant from the refrigerant circuit with time. As a result, compared to the case 71 of FIG. 7 where the distance of the refrigerant pipe 44 from the refrigerator 45 is short, the distance of the refrigerant pipe 44 is longer, and the showcase of FIG. It can be seen that the temperature difference 81 between the evaporator outlet and the inlet with respect to the decrease in the refrigerant amount is very large. That is, the decrease in the refrigerant amount can be detected with high sensitivity only from the refrigerant temperature information relating to the evaporator of the refrigeration showcase under conditions where the refrigerant is difficult to reach sufficiently.

  With this effect, even if multiple refrigeration showcases are connected to a single refrigerator, there is no need to attach temperature sensors to all of the refrigeration showcases. Is a temperature sensor only for evaporators in refrigeration showcases where the refrigerant temperature is likely to change by acquiring and analyzing the measured data of the refrigerant temperature when the refrigerant amount is deliberately changed. The refrigerant leakage can be determined from the data.

  As a result, regardless of the number of objects to be cooled, such as refrigeration showcases connected to the refrigerator, it is possible to build a refrigerant shortage detection device with a small number of temperature sensors and a small number of computing units. It is possible to minimize the cost of And the state with the highest sensitivity is maintained also in the refrigerant | coolant detection performance in that case.

[Effect of the second embodiment]
(Related to claim 2)
FIG. 12 shows the temperature difference 91 between the refrigerant at the outlet and the inlet of the showcase, the signal 93 of the solenoid valve, and the temperature 92 inside the showcase. The top portion 90 in this figure is forcibly closing the electromagnetic valve 93 to evaporate the refrigerant in order to remove the frost adhering to the evaporator, even though the temperature 92 in the showcase chamber rises. We do not let it flow into the vessel. It can be seen that the temperature difference between the inlet and outlet of the evaporator widens by about 2 to 3 degrees at the time 94 when 10 to 20 minutes have passed after the operation for forcibly stopping the refrigerant is released 97. In this refrigerant leak detection, based on this temperature difference, the refrigerant leak is determined such that if the temperature difference is large, the refrigerant leak has occurred. Therefore, this temperature difference 98 causes an erroneous determination. In addition, when the threshold value for determining the temperature difference 98 refrigerant leakage is increased, the minimum value of the refrigerant leakage amount at which the refrigerant leakage can be determined is increased. However, when about 30 minutes have elapsed 96 after the operation 97 forcibly stopping the refrigerant, the warm refrigerant in the evaporator is discharged, and the temperature difference 91 between the evaporator outlet and the inlet refrigerant returns to the original state. 95. Therefore, after the refrigerant is forcibly stopped 90 as in the second embodiment, until the predetermined time 96 has elapsed, the refrigerant temperature data at the outlet and inlet of the evaporator is determined by the condition determination portion of S14 in the flowchart of FIG. Is not read, the refrigerant leakage determination is not performed even if the electromagnetic valve 93 is open. As a result, it is possible to prevent erroneous determination of refrigerant leakage, and determination of refrigerant leakage in consideration of the spread 98 of the temperature difference between the outlet and inlet of the evaporator after the operation 97 forcibly stopping the refrigerant is canceled. It is not necessary to increase the threshold value.

  The above-described state in which an erroneous determination is likely to occur after the operation of forcibly stopping the refrigerant similarly occurs at the minimum refrigerant temperature after the evaporator and the average refrigerant temperature after the evaporator. Therefore, the refrigerant leakage is determined at these temperatures. Even for the system, it is possible to prevent erroneous determination of refrigerant leakage. This makes it possible to construct a highly reliable refrigerant quantity shortage detection device.

  In order to remove the frost adhering to the evaporator as described above, the solenoid valve 93 is forcibly closed and the refrigerant does not flow into the evaporator even though the temperature 92 in the showcase is rising. The same phenomenon as 90 appears when the refrigerant flow is forcibly stopped for inspection of the refrigeration apparatus and when the refrigerant flow is stopped due to a power failure. However, it is possible to prevent erroneous determination of refrigerant leakage by adopting a method in which the refrigerant temperature data at the outlet and inlet of the evaporator is not read until the predetermined time 96 described above.

[Effect of the third embodiment]
(Related to claim 2)
In this embodiment, the flow chart of FIG. 10 is used under the same conditions as in the second embodiment, that is, until the predetermined time elapses 96 after the coolant is forcibly stopped like the head portion 90 of FIG. In S14, the condition determination portion does not perform comparison with the refrigerant leakage determination value in S11 using the determination temperature data calculated in S6 based on the refrigerant temperature data at the outlet and inlet of the evaporator. This embodiment is a method applied when it is desired to always read the refrigerant temperature data at the evaporator inlet and outlet at a constant period. Also in this embodiment, it is possible to prevent erroneous determination of refrigerant leakage, and also consider the spread 98 of the refrigerant temperature difference between the outlet and inlet of the evaporator after releasing 97 the operation of forcibly stopping the refrigerant. Therefore, it is not necessary to increase the threshold value for determining refrigerant leakage.

  Also in the case of the present embodiment, it is possible to prevent erroneous determination of refrigerant leakage even for a method of determining refrigerant leakage based on the minimum refrigerant temperature after the evaporator and the average refrigerant temperature after the evaporator. This makes it possible to construct a highly reliable refrigerant quantity shortage detection device.

  Also, in the case where the refrigerant flow is forcibly stopped for inspection of the refrigeration system, and when the refrigerant flow is stopped due to a power failure, the refrigerant leakage is the same as in the second embodiment. It is possible to prevent erroneous determination.

[Effect of the fourth embodiment]
(Related to claim 3)
FIG. 12 shows the temperature difference 91 between the refrigerant at the outlet and the inlet of the showcase, the signal 93 of the solenoid valve, and the temperature 92 inside the showcase. The top portion 90 in this figure is forcibly closing the electromagnetic valve 93 to evaporate the refrigerant in order to remove the frost adhering to the evaporator, even though the temperature 92 in the showcase chamber rises. We do not let it flow into the vessel. It is found that the temperature difference between the outlet and the inlet of the evaporator is widened by about 2 to 3 degrees at the time 94 when 10 to 20 minutes have passed after the operation for forcibly stopping the refrigerant is released 97. In this refrigerant leak detection, based on this temperature difference, the refrigerant leak is determined such that if the temperature difference is large, the refrigerant leak has occurred. Therefore, this temperature difference 98 causes an erroneous determination. In addition, when the threshold value for determining the temperature difference 98 refrigerant leakage is increased, the minimum value of the refrigerant leakage amount at which the refrigerant leakage can be determined is increased. However, after the operation 97 of forcibly stopping the refrigerant is canceled, the temperature difference 91 between the refrigerant at the outlet and the inlet of the evaporator 94 once widens 94, and then the solenoid valve opening / closing 93 is performed 96 until the time 95 returns to the original state. You can see that it has been done twice. Due to the opening / closing 93 of the electromagnetic valve, the warm refrigerant in the evaporator is discharged, and the temperature difference 94 between the refrigerant at the outlet and the inlet of the evaporator is restored to the original state 95. Therefore, after the refrigerant has been forcibly stopped 90 as in the second embodiment, a method in which the refrigerant temperature data at the evaporator outlet and the inlet is not read until the electromagnetic valve 93 is opened and closed a predetermined number of times, or By adopting a method in which the determination of refrigerant leakage is not performed as in the third embodiment, it is possible to prevent erroneous determination of refrigerant leakage, and the operation of the evaporator after releasing 97 the operation for forcibly stopping the refrigerant is canceled. It is not necessary to increase the threshold value for determining the refrigerant leakage in consideration of the spread 98 of the refrigerant temperature difference between the outlet and the inlet.

  The above-described state in which an erroneous determination is likely to occur after the operation of forcibly stopping the refrigerant similarly occurs at the minimum refrigerant temperature after the evaporator and the average refrigerant temperature after the evaporator. Therefore, the refrigerant leakage is determined at these temperatures. Even for the system, it is possible to prevent erroneous determination of refrigerant leakage. This makes it possible to construct a highly reliable refrigerant quantity shortage detection device.

  In order to remove the frost adhering to the evaporator as described above, the solenoid valve 93 is forcibly closed to evaporate the refrigerant in spite of the rise of the showcase internal temperature 92 as shown in FIG. The same phenomenon as in the case of not flowing into the chamber 90 also appears when the refrigerant flow is forcibly stopped for inspection of the refrigeration apparatus and when the refrigerant flow is stopped due to a power failure. However, it is possible to similarly prevent erroneous determination of refrigerant leakage by adopting a method that does not perform determination of refrigerant leakage until the above-described electromagnetic valve is opened and closed a predetermined number of times.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First embodiment]
As shown in FIG. 1, the compressor 1, the oil separator 2, the condenser 3, the receiver tank 4, the first pipe joint 5, the electromagnetic valve 6, the expansion valve 7, the evaporator 8, the second pipe joint 9, A refrigerant path is connected between the liquid separator 10 and the like by a refrigerant pipe 11 and between the receiver tank 4 and the liquid separator 10 via the electromagnetic valve 6, the expansion valve 7, and the evaporator 8. 1 in the refrigerant circuit of the refrigeration apparatus A provided in parallel (one system in the embodiment of FIG. 1 and eight systems in FIG. 4) upstream of the evaporator 8 and downstream of the expansion valve 7 The first temperature sensor 12 is attached to the part. Further, the second temperature sensor 13 is attached to a portion downstream of the evaporator 8 and before the junction with the other cooling path (second pipe joint 9). The temperature sensor may be of any type, but since the temperature signal is processed by an arithmetic unit such as a microcomputer, it is necessary to obtain some electrical output signal such as a thermocouple or thermistor. The temperature sensor may be attached in such a way as to be in direct contact with the internal refrigerant, or may be a method in which the temperature of the refrigerant is indirectly detected by being attached to the refrigerant pipe 11. However, when it is attached to the refrigerant pipe 11, the temperature sensors 12 and 13 attached to the pipe are covered with a heat insulating material or the like so as not to be affected by the air temperature around the pipe, and the same temperature as the refrigerant temperature as much as possible. It is necessary to take such measures. The outputs of the first temperature sensor 12 and the second temperature sensor 13 are input to the calculator 15 via the electrical signal line 14.

  Further, a drive signal for the electromagnetic valve 6 correlated with the open / closed state of the electromagnetic valve 6 that controls the flow of the refrigerant into the evaporator 8 can be taken out. This is a signal obtained by electrically extracting a voltage signal applied to the electromagnetic valve 6 even if it is a software opening / closing instruction signal in the controller (calculator) 15 that directly instructs the electromagnetic valve 6 to open / close. It may be. When a voltage signal applied to the electromagnetic valve 6 is used, the electric signal line of the electromagnetic valve 6 is input to the calculator 15 as shown in FIG.

  FIG. 4 shows a first embodiment relating to how to attach the temperature sensor. In FIG. 1, there is one showcase to be cooled connected to one refrigerator 18, but in FIG. 4, multiple showcases to be cooled (8 in this figure) are connected. FIG. In the right showcase set 41 in FIG. 4, the refrigerant pipe 44 is long and away from the refrigerator 45. Among them, in the showcase 43 at the end, partial gasification occurs due to the temperature rise of the refrigerant, so that the refrigerant supply amount becomes smaller than other showcases. Further, in the left showcase set 42 in FIG. 4, the refrigerant pipe 44 is not separated from the refrigerator 45, but the refrigerant pipe 44 is connected to the evaporator 49 of the showcase 46 located in the middle. In this case, the refrigerant is taken out from above the pipe. Also in this case, since the gas existing above the refrigerant pipe 44 is easily sucked, the supply amount of the refrigerant is reduced as compared with other showcases. The reason why the refrigerant is taken out from the refrigerant pipe 44 from above is that the pipe layout can be taken out only from above due to the influence of the structure of the store where the refrigeration showcase is installed. In addition, as a condition for reducing the amount of refrigerant supplied to the showcase, a case where the inclination of the refrigerant pipe increases toward the end of the refrigerant pipe 44 can be considered.

  The temperature sensor at the inlet and outlet of the evaporator described above is in the state that the refrigerant is in a liquid state for all of the above-mentioned freezing showcases even when multiple refrigerators are connected to the refrigerator. It is difficult to reach the conditions, or the measured data of the refrigerant temperature when the amount of refrigerant is intentionally changed is obtained and analyzed, and only the refrigeration showcase evaporator, where the refrigerant temperature easily changes, is the temperature. Install the sensor. For example, in the case of FIG. 4, the temperature sensors 47 and 48 are attached only to the showcases 43 and 46 in which the amount of refrigerant supplied is small compared to other showcases.

  FIG. 5 is an example of a refrigerant leakage determination program using the above-described temperature sensor signal and electromagnetic valve signal in the first embodiment. This program is described in the calculator 15 of FIG. 1, and is executed step by step at a predetermined calculation cycle. First, in S1, the drive signal for the solenoid valve (40 in FIG. 4) is read and the drive signal for the solenoid valve 40 is monitored. In S2, it is determined whether the solenoid valve 40 is opened. If the solenoid valve 40 is not opened, monitoring of the opening of the solenoid valve 40 is continued without any other arithmetic processing until the valve is opened. Return to S1 again. When the solenoid valve 40 is opened, the processing after S3 is performed, and the signal processing of the first and second temperature sensors 47 and 48 is started. As a result, the refrigerant flows into the evaporator 49, and the refrigerant leakage is determined only by the data at the time when the refrigeration cycle is established.

  When it is determined that the valve is opened, a memory for storing the refrigerant leak determination temperature data calculation result data at the time of the first valve opening determination is initialized in S3 of FIG. This is because the arithmetic average value of the temperature data for determination is calculated for each valve opening period. Further, in order to calculate the arithmetic average value, the data acquisition count of the temperature sensor is incremented by one in S4. Next, in S5, the signals of the first (inlet) and second (outlet) temperature sensors 47 and 48 of the evaporator portion are read. Then, based on this sensor signal, in the refrigerant leak determination temperature data calculation processing part (S6), the second temperature sensor 48 detects the minimum value of the refrigerant temperature at the evaporator outlet and / or the second temperature sensor. The process of integrating the refrigerant temperature at the evaporator outlet by 48 or the process of integrating the difference between the refrigerant temperature at the evaporator outlet by the second temperature sensor 48 and the refrigerant temperature at the evaporator inlet 47 by the first temperature sensor is performed. .

  After the refrigerant leak determination temperature data calculation process, the drive signal of the solenoid valve 40 is read again in S7 of FIG. Then, in S8, it is determined whether or not the electromagnetic valve 40 is closed.

  When the solenoid valve 40 is not closed, that is, when the valve is still open, the process returns to S4, the count of the data acquisition number of the temperature sensors 47 and 48 is again advanced by one, and then the first and second The temperature sensors 47 and 48 are read (S5), and refrigerant leak determination temperature data calculation processing (S6) is performed.

  When the electromagnetic valve 40 is closed (Yes in S8), the signals of the first and second temperature sensors 47 and 48 are not read, and the evaporator by the second temperature sensor 48 is S9. The integrated value of the refrigerant temperature at the outlet and / or the integrated value of the difference between the refrigerant temperature at the evaporator outlet by the second temperature sensor 48 and the refrigerant temperature at the evaporator inlet by the first temperature sensor 47 are used for each valve opening period. The average value is calculated. At this time, the average value is calculated by dividing each integrated value by the count value of the temperature sensor data acquisition count (count value in S4).

  Thus, the minimum value of the refrigerant temperature at the evaporator outlet and / or the average refrigerant temperature at the evaporator outlet and the average refrigerant temperature difference between the evaporator outlet and the inlet as shown in FIG. 8 during one valve opening period. A value, that is, temperature data for refrigerant leakage determination is calculated.

  The refrigerant leak determination temperature data calculated for each valve opening period has a certain amount of variation at each timing due to disturbances such as ambient temperature changes, device operation variations, noise (electrical), and the like. In order to reduce the influence of this variation, a sequential averaging process such as a first-order lag process is applied to the refrigerant leak determination temperature data calculated for each valve opening period in S10 of FIG.

  The following equation (Equation 1) is an example of a first-order lag process used as a sequential averaging process in S10. y is the average value of the first-order lag processing, u is the temperature data for refrigerant leakage judgment before the first-order lag processing, Ts is the sampling period of the temperature sensor signal (the calculation timing of the program in the calculator), and T is the first-order lag processing The weight, i.e., the time constant, and the subscript k represent the timing of sampling or calculation. That is, k−1 represents a calculation value at the previous calculation timing or a sampling value of the temperature sensor signal at the previous sampling timing.

  By comparing the refrigerant leak determination temperature data subjected to the averaging process with the refrigerant leakage determination value, an abnormality determination is performed in S11 of FIG. If an abnormality determination is made, an abnormality determination process such as lighting of a refrigerant leak lamp is performed at S12, and if a normal determination is made, a normal determination process such as lighting of a normal lamp is performed at S13. After the normality / abnormality determination process is completed, the process returns to S1 again, reads the solenoid valve drive signal 40, and repeats the above process.

  Further, the refrigerant leakage determination program can be changed to a simplified program so as not to calculate the average value for each valve opening period as shown in FIG.

[Second embodiment]
FIG. 9 shows a second embodiment, which is an embodiment of claim 2. The condition determination process of S14 is added between S2 and S5 with respect to the program flowchart of FIG. 6 shown in the first embodiment. In S14, the temperature of the object to be cooled, such as the inside temperature of the showcase, is increased, and the flow of the refrigerant is reduced by closing the solenoid valve in spite of the condition that the refrigerant should flow into the evaporator. In the case where the condition has been forcibly stopped, it is determined whether a predetermined time has elapsed since the state was released. As a result, if the predetermined time has not elapsed, the process proceeds to the next loop without reading the temperature data of the inlet and outlet of the evaporator.

  In the case of the program shown in FIG. 5, the determination in S14 described above is incorporated between S2 and S3.

  In addition, this method is applicable regardless of the number of refrigerant paths connected to the refrigeration apparatus.

[Third embodiment]
FIG. 10 shows a third embodiment, which is an embodiment of claim 2. The condition determination process of S14 is added between S10 and S11 to the flowchart of the program of FIG. 6 shown in the first embodiment. In S14, the temperature of the object to be cooled, such as the inside temperature of the showcase, is increased, and the flow of the refrigerant is reduced by closing the solenoid valve in spite of the condition that the refrigerant should flow into the evaporator. In the case where the condition has been forcibly stopped, it is determined whether a predetermined time has elapsed since the state was released. As a result, when the predetermined time has not elapsed, the process proceeds to the next loop without performing the refrigerant leakage determination process using the calculation result of the determination temperature data.

  In the case of the program shown in FIG. 5, the determination in S14 described above is incorporated between S10 and S11.

  In addition, this method is applicable regardless of the number of refrigerant paths connected to the refrigeration apparatus.

[Fourth embodiment]
FIG. 11 shows a fourth embodiment, which is an embodiment of claim 3. The condition determination process of S15 is added between S1 and S2 with respect to the flowchart of the program of FIG. 6 shown in the first embodiment. In S15, the temperature of the object to be cooled, such as the inside temperature of the showcase, is increased, and the flow of the refrigerant is reduced by closing the solenoid valve even though the refrigerant should flow through the evaporator. If the condition has been forcibly stopped, it is determined whether the solenoid valve has been opened and closed a predetermined number of times after the state is canceled. As a result, when the solenoid valve has not been opened and closed a predetermined number of times, the process proceeds to the next loop without performing the refrigerant leakage determination process using the calculation result of the determination temperature data.

  In the case of the program shown in FIG. 5, the determination in S15 described above is incorporated between S2 and S3. Further, in the case of this method, as in the third embodiment, S15 can be established even if it is incorporated between S10 and S11.

  In addition, this method is applicable regardless of the number of refrigerant paths connected to the refrigeration apparatus.

  Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

The present invention relates to a refrigeration / refrigeration facility for a refrigeration showcase for display and sale of foodstuffs, an air conditioning facility for a store / building / house, etc., and a refrigeration / refrigeration facility using a refrigerant such as a refrigerator / vending machine. Can be used.

1 is a general configuration drawing of a refrigeration / refrigeration / air conditioning facility to which the present invention is applied. It is the figure which demonstrated the prior art with the general block diagram of freezing, refrigeration, and air-conditioning equipment. It is a figure explaining the problem of the prior art of freezing, refrigeration, and air-conditioning equipment. It is a figure showing the structure of the 1st Example. It is the figure which represented the example of the program part in a 1st Example with the flowchart. It is the figure which represented the example of the program part in a 1st Example with the flowchart. It is a figure showing the effect of a 1st Example. It is a figure showing the effect of a 1st Example. It is the figure which represented the 2nd Example with the flowchart. It is the figure which represented the 3rd Example with the flowchart. It is the figure which represented the 4th Example with the flowchart. It is a figure explaining the effect of 2nd, 3rd, 4th Example.

Explanation of symbols

A: Refrigeration apparatus, 1: Compressor, 2: Oil separator, 3: Condenser, 4: Receiver tank, 5: Pipe joint, 6: Solenoid valve, 7: Expansion valve, 8: Evaporator, 9: Second Pipe joint, 10: liquid separator, 11: piping for refrigerant, 12: first temperature sensor, 13: second temperature sensor, 14: electrical signal line, 15: calculator, 16: outlet of evaporator, 17: Evaporator inlet, 18: Refrigerator, 19: Showcase, 20: Evaporator, 21: Evaporator inlet, 22: Evaporator outlet, 23: Showcase, 24: Refrigerant circuit, 24a: First pipe joint 24b: second pipe joint, 25: compressor, 26: refrigerator, 27: solenoid valve, 28: oil separator, 29: condenser, 30: solenoid valve for forced defrosting Closed period, 31: refrigerant temperature difference between the inlet and outlet of the evaporator, 32: temperature inside the showcase, 33: electricity Open / close signal of valve, 34: condition for resuming refrigerant flow, 35: condition for refrigerant coming out of warm evaporator, 37: liquid separator, 38: expansion valve, 39: receiver tank, 40: solenoid valve 41: Set of right showcase, 42: Set of left showcase, 43: Showcase at end of refrigerant pipe, 44: Refrigerant pipe, 45: Refrigerator, 46: Refrigerant pipe taken out from above pipe Showcase taken out, 47: first temperature sensor, 48: second temperature sensor, 49: evaporator, 50: compressor, 51: condenser, 71: refrigerant outlet and inlet refrigerant temperature Difference: 72: Solenoid valve open / close signal, 81: Temperature difference between refrigerant at outlet and inlet of evaporator, 82: Solenoid valve open / close signal, 90: Period for forcibly closing solenoid valve for defrosting of evaporator 91: Refrigerant outlet and inlet refrigerant temperatures , 92: Showcase interior temperature, 93: Solenoid valve open / close signal, 94: Refrigerant flow resumed condition, 95: Refrigerant warmed-up refrigerant condition, 96: Solenoid valve pre-determined number of times Period of opening and closing, 97: instant of releasing the operation for forcibly stopping the refrigerant, 98: spread of the refrigerant temperature difference between the outlet and the inlet of the evaporator.

Claims (3)

In the refrigerant leakage detection method for a refrigeration apparatus, the evaporator connected to a single chiller is characterized in that the refrigerant amount of the refrigeration apparatus is determined based on the outlet of the evaporator and / or the refrigerant at the inlet or a temperature corresponding to the refrigerant. When there are a plurality of units, the sensitivity of the temperature with respect to a decrease in the amount of refrigerant in the refrigeration apparatus is higher than that of other evaporators, and the refrigerant temperatures of the evaporators whose number is equal to or less than the total number of connected evaporators A refrigerant leakage detection method for a refrigeration apparatus, wherein the refrigerant amount of the refrigeration apparatus is determined using a detection result. In a refrigerant leakage detection method for a refrigeration apparatus, wherein the refrigerant amount of the refrigeration apparatus is determined based on an evaporator outlet and / or a refrigerant temperature at the inlet or a temperature corresponding to the refrigerant. Does not determine the amount of refrigerant until a predetermined time has elapsed after resuming inflow / outflow of refrigerant into the evaporator when the flow of refrigerant is stopped even under conditions where refrigerant should flow in / out of the evaporator, or A refrigerant leakage detection method for a refrigeration apparatus, wherein abnormality determination is not performed based on a determination result of the refrigerant amount. In a refrigerant leakage detection method for a refrigeration apparatus, wherein the refrigerant amount of the refrigeration apparatus is determined based on an evaporator outlet and / or a refrigerant temperature at the inlet or a temperature corresponding to the refrigerant. If the refrigerant flow is stopped even if the refrigerant should flow into and out of the evaporator, after the refrigerant flow into and out of the evaporator is resumed, until the solenoid valve that controls the refrigerant is activated a predetermined number of times A refrigerant leak detection method for a refrigeration apparatus, wherein the refrigerant quantity is not determined, or the abnormality determination is not performed based on the determination result of the refrigerant quantity.