JPH09303912A - Method for sensing abnormal state in freezing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sensing an abnormal state capable of preventing a frequent stop of a compressor from occurring even when it is not required. SOLUTION: A thermistor is fitted to either a refrigerant pipe between an outlet of a condenser and an inlet of an evaporator or a drier. A first reference temperature x1 is set as a reference for discriminating if a thermal radiation at the condenser is normally carried out or in abnormal state and a saturation temperature of the refrigerant kept at a substantial equal pressure as that operated to cause the prior art pressure switch to stop the operation of the compressor is set as a second reference temperature x2 as a reference for protecting the compressor. When a refrigerant temperature attained by the thermistor exceeds the first reference temperature, an alarm is generated to inform an abnormal thermal radiation of the condenser, a time in which the refrigerant temperature continues to exceed he second reference temperature is measured as a first discriminating time t1 and when the first discriminating time becomes more than the predetermined time, it is set as a abnormal pressure in the compressor and the compressor is stopped.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a compressor, a condenser,
The present invention relates to the technology of a refrigeration circuit including an expansion valve, an evaporator, and the like, and particularly to a method of detecting an abnormality in the refrigeration circuit.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional general refrigeration circuit 5 used in refrigerators, ice makers and the like. The refrigeration circuit 5 includes a compressor 7, a condenser 9, a dryer 11, and
It is composed of an expansion valve 13 and an evaporator 15. The dryer 11 was fixed at a predetermined position by a dryer fixing tool 23. The dryer fixture 23 fixes the dryer 11 against vibration of the refrigerator parts and prevents leakage of the refrigerant gas caused by breakage of the refrigerant pipe or breakage of the connection between the refrigerant pipe and the dryer. It worked and was used in most of the conventional refrigeration circuits with dryers.
In the refrigeration circuit 5, the refrigerant is first adiabatically compressed in the compressor 7 and sent to the condenser 9 via the refrigerant pipe a.
The refrigerant in the condenser 9 is cooled there, liquefied, and sent to the dryer 11 via the refrigerant pipe b. Water and the like are removed from the refrigerant in the dryer 11, and the refrigerant is sent to the expansion valve 13. The refrigerant sent to the expansion valve 13 is then adiabatically expanded to a state where it is easily vaporized and sent to the evaporator 15. The refrigerant sent to the evaporator 15 takes heat from the surroundings of the evaporator 15 to be vaporized, and then returns to the compressor 7.

The conventional refrigeration circuit 5 is provided with some members for detecting an abnormality in the circuit. First, the refrigerant pipe a between the compressor 7 and the condenser 9 is provided with a pressure switch 17 for detecting an abnormality in the refrigerant pressure. The pressure switch 17 is attached to the refrigerant pipe a by welding. Next, the thermistor 19 for measuring the temperature of the refrigerant is attached to the refrigerant pipe b between the condenser 9 and the dryer 11 by the temperature sensing section attaching means 25. One end of the lead wire 27 is connected to the thermistor 19, and the other end is connected to the temperature detector 21.

In the refrigeration circuit 5, when the outlet pressure of the compressor 7, that is, the refrigerant pressure in the refrigerant pipe a becomes higher than a predetermined value, it is considered that an abnormal pressure of the refrigerant has occurred and the pressure switch 17
Is activated and the operation of the compressor 7 is stopped. Further, from the temperature measured by the temperature detector 21, it is possible to detect the occurrence of an abnormality due to insufficient heat release of the condenser 9 or the like.

[0005]

However, the above-mentioned conventional refrigeration circuit 5 has the following problems in accurately detecting an abnormality. Since the pressure switch 17 is connected to the refrigerant pipe a by welding as described above, if there is a defective welding at the connection portion, the refrigerant gas may be released into the atmosphere, and it takes a lot of time to repair it. Was needed. In addition, when repairing the damaged pressure switch 17, there is a problem that the refrigerant must be discharged into the atmosphere.
Further, since the compressor 7 is stopped only when the refrigerant pressure in the refrigerant pipe a becomes higher than a predetermined value, the compressor 7 is repeatedly stopped in a short time, causing abnormal heat generation of the compressor 7. It was found that there is a fear that it is not preferable from the viewpoint of compressor protection.

Therefore, the present invention has been made to solve the above-mentioned problem which is not preferable in detecting an abnormality, and provides a method for detecting an abnormality in a refrigeration circuit which does not frequently stop the compressor until it is not necessary. The purpose is to provide. Further, specifically, an object of the present invention is to provide an anomaly detection method capable of protecting a compressor without using a pressure switch and capable of performing several kinds of anomaly detection with less temperature measuring means. .

[0007]

In order to achieve the above object, a method for detecting abnormality in a refrigeration circuit according to the present invention according to claim 1 is a refrigeration circuit comprising a compressor, a condenser, an expansion valve and an evaporator. The outlet of the condenser and the inlet of the evaporator are provided with temperature measuring means for measuring the temperature of the refrigerant in the communicating portion,
A first reference temperature of the refrigerant is set as a reference for determining whether heat dissipation in the condenser is normally performed or abnormal, and a second reference temperature of the refrigerant is set as a reference for protecting the compressor. And when the temperature of the refrigerant measured by the temperature measuring means exceeds the first reference temperature, an alarm is issued as an abnormal heat radiation of the condenser, and the temperature of the refrigerant exceeds the second reference temperature. First time to continue
It is measured as a determination time, and when the first determination time is longer than a predetermined time, it is determined that the pressure of the compressor is abnormal, and the compressor is stopped. As a result, both the protection of the compressor and the detection of the heat radiation abnormality of the condenser can be performed by the single temperature measuring means.

According to the abnormality detecting method of the present invention as set forth in claim 2, the condenser is provided with a condenser fan for promoting heat radiation in the condenser, and after the compressor is stopped,
The time until the temperature of the refrigerant reaches the first reference temperature is measured as the second determination time, and it is determined from the second determination time whether or not there is an abnormality in the condenser fan.
Further, according to the present invention as set forth in claim 3, the condenser is provided with a condenser fan for promoting heat radiation in the condenser, and the temperature of the refrigerant is kept constant after the compressor is stopped. The time until reaching the first reference temperature is measured as a second determination time, and the compressor is restarted when the temperature of the refrigerant reaches the first reference temperature, and after restarting the compressor. The time until the compressor is stopped when the first determination time becomes a predetermined time or more again is measured as the third determination time,
From the second and / or third determination time, it is determined whether or not the condenser fan has an abnormality. Claims 2 and 3
According to the present invention described in (1), an abnormality of the condenser fan can be detected in one cycle, and the compressor can be stopped before a frequent operation stop state occurs, thus protecting the compressor.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. FIG. 1 shows an example of a refrigeration circuit 105 in which the abnormality detection method of this embodiment is implemented. Refrigeration circuit 10
5 comprises a compressor 107, a condenser 109, an expansion valve 113 and an evaporator 115. One end of the refrigerant pipe a is connected to the refrigerant outlet end of the compressor 107, and the other end is connected to the condenser 1
09 is connected to the refrigerant inlet end. One end of the refrigerant pipe b is connected to the refrigerant outlet end of the condenser 109, and the other end is connected to the inlet end of the expansion valve 113. Expansion valve 1
One end of the refrigerant pipe c is connected to the refrigerant outlet end of 13, and the other end is connected to the refrigerant inlet end of the evaporator 115. One end of the refrigerant pipe d is connected to the outlet end of the evaporator 115, and the other end is connected to the inlet end of the compressor 107. As a result, the refrigerant circulates in the refrigeration circuit 105, as indicated by the one-dot chain line arrow in FIG.

In the vicinity of the condenser 109, the condenser 109
A fan 131 is provided to promote heat dissipation from the refrigerant. A thermistor (temperature measuring means) 119 is attached to the refrigerant pipe b between the condenser 109 and the expansion valve 113. The thermistor 119 is connected to one end of a lead wire 127 which constitutes a part of the temperature measuring means, and the other end is connected to a temperature detector (temperature measuring means) 121. The temperature detector 121 receives a signal from the thermistor 119 via the lead wire 127 and detects the refrigerant temperature. The temperature detector 121 is electrically connected to a determination / control device 133 such as a microcomputer, which is conceptually shown as a block in FIG. Therefore, the temperature detector 1
The information on the temperature detected in 21 is used as the judgment / control device 133.
And is compared there with some reference temperatures to make a determination, as will be described below. Judgment / control device 133
Is also electrically connected to the compressor 107.

Next, the circulation of the refrigerant in the refrigeration circuit 105 will be described. The refrigerant that has flowed into the compressor 107 is adiabatically compressed into high-pressure gas, passes through the refrigerant pipe a, and enters the condenser 109.
Sent to The refrigerant flowing into the condenser 109 releases heat to the outside and is cooled and liquefied. At this time, more heat is released from the refrigerant by the fan 131,
The refrigerant is designed to be cooled. The liquid refrigerant cooled in the condenser 109 passes through the refrigerant pipe b and the expansion valve 11
Sent to 3. The expansion valve 113 adiabatically expands the liquid refrigerant so that it is easily vaporized. The refrigerant flowing out from the expansion valve 113 is sent to the evaporator 115 through the refrigerant pipe c, where heat is taken from the outside to be vaporized. As a result, the periphery of the evaporator 115 is cooled. The vaporized refrigerant returns to the compressor 107 through the refrigerant pipe d.

Next, detection of abnormality of the refrigeration circuit 105 will be described. FIG. 2A is a diagram showing a change over time in the refrigerant temperature in the refrigerant pipe b, which is measured by the temperature measuring means including the thermistor 119, the lead wire 127, and the temperature detector 121, and FIG. FIG. 4 is a diagram showing an alarm regarding the condenser 109 corresponding to (a) and the operation timing of the compressor 107 and the fan 131.

In FIG. 2A, reference numeral x1 is
It is the first reference temperature that serves as a reference for determining whether heat dissipation in the condenser 109 is normally performed or abnormal. Reference numeral x2 is a second reference temperature that serves as a reference for protecting the compressor. The first reference temperature x1 and the second reference temperature x2 differ depending on the type of the refrigerant used, the ambient temperature, the capacity of the refrigerator including the refrigeration circuit, and the like, but the first reference temperature x1
It is advisable to determine the optimum value in advance through experiments or the like. On the other hand, regarding the second reference temperature x2, when the present abnormality detection method is performed in the refrigeration circuit that has conventionally protected the compressor with the pressure switch, the pressure value that the pressure switch operated to stop the compressor and It is preferable to set the saturation temperature of the refrigerant at approximately the same pressure, and when the target is a refrigeration circuit that does not have a pressure switch, the optimum value for protecting the compressor should be determined by experiments etc. Good.

In the refrigeration circuit 105 described above, for example, oil or dust adheres to the condenser 109 or the condenser 10
When the inside of 9 is clogged for some reason or the outside air temperature rises, and the heat radiation from the refrigerant in the condenser 109 is not normally performed, the refrigerant temperature in the refrigerant pipe b becomes as shown in FIG. As shown, the temperature rises above the normal temperature x0. When the determination / control device 133 determines that the refrigerant temperature measured by the temperature detector 121 has reached the first reference temperature x1, as shown in (b) of FIG. An alarm will be issued to inform you of the shortage.

As shown in FIG. 2A, when the fan 131 has some trouble, the refrigerant temperature exceeds the first reference temperature x1, and the judgment / control device 133 causes the second reference temperature to be exceeded. When it is determined that x2 has been reached, as shown in FIG. 2B, an alarm is issued to notify the occurrence of an abnormality in the condenser 109. This alarm can be generated by a known means such as an alarm lamp or an alarm buzzer. Further, at the same time when the refrigerant temperature reaches the second reference temperature x2, a well-known timer (not shown) that may be incorporated in the determination / control device 133 is activated. The timer measures the time during which the refrigerant temperature exceeds the second reference temperature x2, and this time is determined by the determination / control device 133.
Is recognized and monitored as the first determination time t1.
When the first determination time t1 is equal to or longer than the predetermined time, the determination / control device 133 stops the compressor 107 in order to protect the compressor 107, as shown in FIG. Therefore, even if the refrigerant temperature fluctuates around the second reference temperature x2 in a short cycle, the compressor 107 does not stop, and it is prevented that the compressor 107 repeatedly operates and stops to cause abnormal heat generation. Further, since the necessity of stopping the compressor 107 is not directly determined only from the measured temperature, it is possible to make an accurate determination that is unlikely to be affected by external factors such as noise and contact failure. The length of the predetermined time may be set to the most convenient length according to the type of refrigerant used, the ambient temperature, the capacity of the refrigerator, and the like. Further, the stop of the compressor 107 is notified to the user by an alarm, as in the case of notifying the abnormality occurrence of the condenser 109 described above.

When the compressor 107 is stopped, the refrigerant temperature is
As shown in FIG. 2A, it gradually decreases.
Here, the above-mentioned timer starts the measurement of the determination time different from the first determination time t1 at the same time when the first determination time t1 becomes the predetermined time or more and the compressor 107 stops. That is, the timer measures the time from when the compressor 107 stops until the refrigerant temperature decreases to the first reference temperature x1.
This time is recognized as the second determination time t2 by the determination / control device 133. Then, the determination / control device 1
When it is determined by 33 that the refrigerant temperature has decreased to the first reference temperature x1, the determination / control device 133 restarts the compressor 107, as shown in FIG.

After that, when the refrigerant temperature rises again after the compressor 107 is restarted and the refrigerant temperature exceeds the second reference temperature x2, the first judgment time t1 is monitored in the same manner as described above, and the first judgment time t1. If the value exceeds a predetermined time, the determination / control device 1 is activated in order to protect the compressor 107 as described above.
The compressor 107 is stopped again by 33. During this period, the above-mentioned timer measures the time from the restart until the compressor 107 is stopped again, and this time is recognized by the judgment / control device 133 as the third judgment time t3.

The second determination time t2 and the third determination time t3 thus measured vary depending on the operating state of the fan 131. That is, as described above, even after the compressor 107 is stopped, the operation signal is continuously sent to the fan 131 (see FIG. 2B), and if the fan 131 functions normally, the fan 131 operates normally. The second determination time t2 tends to be shortened as compared with the case where 131 is locked and is not rotating or is not rotating properly.
Then, the third determination time t3 shows an extension tendency.

FIG. 3 is a diagram showing changes over time in the refrigerant temperature when the fan 131 is abnormal and when the fan 131 is normal. In FIG. 3, a point F indicates a time when the first determination time t1 is equal to or longer than the predetermined time and the compressor 107 is stopped, and a dotted line after the point F is a refrigerant when the fan 131 is functioning normally. The time-dependent change in temperature, the solid line after point F indicates the time-dependent change in refrigerant temperature when the fan 131 is abnormal. The second determination time t2 ′ when the fan 131 functions normally is the fan 1
Since the heat radiation from the refrigerant in the condenser 109 is favorably performed by the rotation of the condenser 31, it becomes shorter than the second determination time t2 when the fan 131 is abnormal. On the other hand, the third determination time t3 ′ when the fan 131 functions normally
Even when the refrigerant temperature is rising due to the activation of the compressor 107, the fan 131 is rotated to appropriately radiate heat from the refrigerant in the condenser 109, so that the refrigerant temperature easily reaches the second reference temperature x2. Fan 13 does not rise
It becomes longer than the third determination time t3 when the abnormality occurs in No. 1. Therefore, regarding the operating state of whether the fan 131 is normal or abnormal in advance, the relationship between the second determination times t2 and t2 ′, the relationship between the third determination times t3 and t3 ′, or the second determination time t2. , T2 ′ and the third determination time t3, t3 ′, the abnormality of the fan 131 can be detected from the actually measured second determination time and third determination time.

In this embodiment, the first judgment time t1
Is measured for a predetermined time or more, the number of times the compressor 107 is stopped is measured, and when the number of times reaches a predetermined set number, for example, 3 times or more, a circuit for prohibiting the activation of the compressor 107 (Fig. (Not shown) is preferable.

As described above, in this embodiment, the expensive pressure switch is not used, and the compressor 107 is protected and the condenser is protected by the single temperature measuring means including the thermistor 119 and the temperature detector 121. The heat radiation abnormality of 109 and the operation abnormality of the fan 131 are detected to prevent gas leakage due to defective welding and reduce costs. Also, even if the used refrigerant, the compressor 107, or the condenser 109 is replaced with a different one, it is not necessary to change other parts by resetting the predetermined time or the reference temperature.

Next, a modified embodiment of the present invention will be described. Since the determination / control device 133 is not provided in the refrigeration circuit (not shown) in which the abnormality detection method of the modified embodiment is implemented, it is attached to various devices or members included in the refrigeration circuit 105 in FIG. 1. Description will be given using the reference numerals. Therefore, please refer to FIG. 1 together with FIG. 4 as appropriate.

Detection of an abnormality in the refrigeration circuit by the method of this modified embodiment will be described. FIG. 4A is a diagram showing a change over time in the refrigerant temperature in the refrigerant pipe b, which is measured by the temperature measuring means including the thermistor 119, the lead wire 127, and the temperature detector 121, and FIG. Is
It is a figure which shows the alarm regarding the condenser 109 corresponding to (a) of FIG. 4, and the operation timing of the compressor 107. In FIG. 4A, the first reference temperature x1 and the second reference temperature x
2 is defined similarly to the first reference temperature x1 and the second reference temperature x2 in the above-described embodiment. Refrigeration circuit 105
When the heat radiation from the refrigerant in the condenser 109 is no longer performed normally, the refrigerant temperature in the refrigerant tube b rises above the normal temperature x0 as shown in FIG. 4 (a). When the refrigerant temperature measured by the temperature detector 121 reaches the first reference temperature x1, as shown in FIG. 4 (b), an alarm is issued to notify the heat radiation amount of the condenser 109 is insufficient.

When the refrigerant temperature rises above the first reference temperature x1 and reaches the second reference temperature x2, such as when the fan 131 has some trouble, as shown in FIG. 4 (b). An alarm is issued to notify the occurrence of an abnormality in the condenser 109, and the compressor 107 is stopped to protect the compressor 107. As a result, without using an expensive pressure switch, it becomes possible to protect the compressor 107 and detect the heat radiation abnormality of the condenser 109 with the single thermistor 119 and the temperature detector 121, and prevent gas leakage due to welding failure. Cost reduction is achieved. Also, even if the used refrigerant, the compressor 107, or the condenser 109 is replaced with a different one, it is not necessary to change other parts by resetting the predetermined time or the reference temperature.

Next, another modified embodiment of the present invention will be described. FIG. 5A shows a refrigeration circuit 205 in which the abnormality detection method of the modified embodiment is implemented, and the refrigeration circuit 205 includes a determination / control device 133 and a switching device 2.
The refrigeration circuit 105 may be similar to the above-described refrigeration circuit 105 shown in FIG. 1 except that 35 is electrically connected.

In the switching device 235, the temperature switching circuit 241 shown in FIG. 5B for changing the above-mentioned second reference temperature x2, and in FIG. 5 (for changing the above-mentioned predetermined time). The time switching circuit 243 shown in c) is provided. Here, the second reference temperature x2 is preferably set to the saturation temperature of the refrigerant at a pressure substantially equal to the pressure value at which the pressure switch was operating to stop the compressor as described above. The temperature varies depending on the type of refrigerant as shown in the table below. Further, the rate of pressure increase of the refrigerant varies depending on the capacity of the refrigerator including the refrigeration circuit, that is, the amount of refrigerant circulation. The following table shows the saturation temperature with respect to the pressure for each type of refrigerant.

[0027]

[Table 1]

Therefore, in this modified embodiment, the temperature switching circuit 241 and the time switching circuit 243 are used to set the second reference temperature x2 depending on the refrigerant used and the capacity of the refrigerator.
The time until the compressor or the compressor 107 is stopped, that is, the above-mentioned predetermined time is suitably changed. The setting switching of the temperature switching circuit 241 and the time switching circuit 243 is performed by the refrigerant selection switch 237 and the setting switch 239 provided in the switching device 235. In the modified embodiment, the refrigerant selection switch 237 and the setting switch 239 may be so-called “toggle switches” that can be switched by linearly operating the lever.

The detection of abnormality in this modified embodiment will be described. FIG. 6A shows the thermistor 119 and the lead wire 1.
It is a figure which shows the time-dependent change of the refrigerant temperature in the refrigerant pipe b measured by the temperature measuring means which consists of 27 and the temperature detector 121, (b) of FIG. 6 is a condenser corresponding to (a) of FIG. FIG. 3 is a diagram showing an alarm regarding 109 and the operation timing of the compressor 107. First, as described above, R-
The temperature selection circuit 241 is switched by the refrigerant selection switch 237 according to the refrigerant to be used, such as 12, R-134a, R22, etc., and the second reference temperature x2 most suitable for the refrigerant is selected.
In addition, the setting switch 23 is set according to the capacity of the refrigerator.
The time switching circuit 243 is switched by 9 to set the optimum length of the predetermined time.

In the refrigeration circuit 205, when heat dissipation from the refrigerant in the condenser 109 is not normally performed, the refrigerant temperature in the refrigerant pipe b is as shown in FIG. 6 (a).
It rises above the normal temperature x0. When the refrigerant temperature measured by the temperature detector 121 reaches the first reference temperature x1,
As shown in FIG. 6 (b), an alarm is issued to notify the insufficient heat radiation amount of the condenser 109.

Further, as shown in FIG. 6A, the refrigerant temperature rises above the first reference temperature x1 when the fan 131 has some trouble, and the determination / control device 133 causes the refrigerant temperature to rise. When it is determined that the temperature reaches the 2 reference temperature x2, as shown in (b) of FIG. 6, an alarm for notifying the occurrence of abnormality of the condenser 109 is issued. This alarm can be generated by, for example, an alarm lamp or an alarm buzzer as described above. Further, at the same time when the refrigerant temperature reaches the second reference temperature x2, a well-known timer (not shown) that may be incorporated in the determination / control device 133 is activated. The timer measures the time during which the refrigerant temperature continues to exceed the second reference temperature x2, and this time is recognized and monitored by the judgment / control device 133 as the first judgment time t1. Then, when the first determination time t1 becomes a predetermined time or more,
As shown in (b) of FIG. 7, the determination / control device 133 stops the compressor 107 in order to protect the compressor 107. Therefore, without using an expensive pressure switch, the single temperature measuring means including the thermistor 119 and the temperature detector 121 can protect the compressor 107 and detect the heat radiation abnormality of the condenser 109, thus resulting in poor welding. The gas leakage prevention and the cost reduction are achieved. Also, for several different refrigerants and refrigerators with different capacities,
Since this modified embodiment can be easily dealt with, there is no problem such as a mistake in mounting or a mistake in wiring due to a change in the specifications of the temperature detector 121, the judgment / control device 133, or the like. In addition, since this modified embodiment can be performed on the same electronic substrate, it can be easily made into a series and can be implemented at low cost.

[0032]

As described above, according to the present invention as set forth in claim 1, the first reference temperature of the refrigerant is used as a reference for judging whether the heat radiation in the condenser is normally performed or abnormal. Set the second reference temperature of the refrigerant as a reference to protect the compressor, and when the temperature of the refrigerant exceeds the first reference temperature, an alarm is issued as an abnormal heat radiation of the condenser, and the temperature of the refrigerant is When the time over which the second reference temperature is maintained exceeds the predetermined time, it is determined that the pressure of the compressor is abnormal. Therefore, both the protection of the compressor and the detection of the heat radiation abnormality of the condenser are performed by the single temperature measuring means. Therefore, the expensive high-voltage switch used in the prior art can be omitted. Therefore, not only is the production cost of the refrigeration circuit reduced, but the possibility of refrigerant gas leaking due to welding defects associated with the installation of the high pressure switch is eliminated, and the troublesome work of removing the refrigerant when the high pressure switch fails is eliminated. Is improved. Further, when the temperature of the refrigerant continues to exceed the second reference temperature for a predetermined time or longer, the compressor is determined to be abnormal and the operation is stopped. Therefore, detection of abnormal pressure causes noise, contact failure of electric elements, etc. It is done accurately without any external influence, and as a result, the compressor can be protected.

According to the present invention as defined in claim 2,
The time from when the compressor stops until the refrigerant temperature returns to the first reference temperature is measured as the second determination time, and it is determined from the second determination time whether the condenser fan has an abnormality. And according to the invention as defined in claim 3,
Furthermore, the time from when the compressor stops until the refrigerant temperature returns to the first reference temperature is measured as the second determination time, and when the temperature returns to the first reference temperature, the compressor is restarted. Then, the time from the restart to the restart of the compressor after the first determination time becomes equal to or longer than the predetermined time is measured as the third determination time, and the condenser is calculated from the second and / or the third determination time. In order to determine whether or not there is an abnormality in the fan, in other words, it is possible to detect an abnormality in the condenser fan in one cycle of restarting and re-stopping the compressor, and compress the compressor before a frequent shutdown condition occurs. Since the machine can be stopped, the compressor can be protected more reliably.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a refrigeration circuit in which an abnormality detection method according to an embodiment of the present invention is implemented.

FIG. 2 (a) is a diagram showing a change over time in the refrigerant temperature in a refrigerant pipe connecting the condenser and the expansion valve in the present embodiment, and FIG. 2 (b) corresponds to FIG. 2 (a). It is a figure which shows the alarm regarding the condensed condenser, and the operation timing of a compressor and a fan.

FIG. 3 is a diagram showing a change over time in the refrigerant temperature when the fan is abnormal and when the fan is normal.

FIG. 4 (a) is a modified embodiment of the present invention,
It is a figure which shows the time-dependent change of the refrigerant temperature in the refrigerant pipe which connects a condenser and an expansion valve, (b) shows the alarm regarding the condenser corresponding to (a) of FIG. 4, and the operation timing of a compressor. It is a figure.

5A is a refrigeration circuit in which an abnormality detection method according to another modified embodiment of the present invention is implemented, FIG. 5B is a temperature switching circuit, and FIG. 5C is a time switching circuit. FIG.

FIG. 6 (a) is a diagram showing a change over time in the refrigerant temperature in the refrigerant pipe connecting the condenser and the expansion valve in yet another modified embodiment of the present invention, and FIG. It is a figure which shows the alarm regarding the condenser corresponding to (a) of FIG.

FIG. 7 is a diagram showing a conventional general refrigeration circuit.

[Explanation of symbols]

105, 205 ... Refrigeration circuit, 107 ... Compressor, 109
… Condenser, 113… Expansion valve, 115… Evaporator, 119…
Thermistor (temperature measuring means) 121 ... Temperature detector (temperature measuring means) 127 ... Lead wire (temperature measuring means), 1
31 ... Condenser fan, 133 ... Judgment / control device, a to d
... Refrigerant tube, x1 ... First reference temperature, x2 ... Second reference temperature,
t1 ... 1st determination time, t2, t2 '... 2nd determination time, t
3, t3 '... Third determination time.

Claims (3)

[Claims] 1. A refrigeration circuit comprising a compressor, a condenser, an expansion valve and an evaporator, wherein a temperature measuring means for measuring the temperature of the refrigerant is provided at a communication part between an outlet of the condenser and an inlet of the evaporator, A first reference temperature of the refrigerant is set as a reference for determining whether heat dissipation in the condenser is normally performed or abnormal, and a second reference temperature of the refrigerant is set as a reference for protecting the compressor. And when the temperature of the refrigerant measured by the temperature measuring means exceeds the first reference temperature, an alarm is issued as an abnormal heat radiation of the condenser, and the temperature of the refrigerant exceeds the second reference temperature. A method for detecting an abnormality in a refrigeration circuit, in which the duration is measured as a first determination time, and when the first determination time exceeds a predetermined time, it is determined that the compressor has a pressure abnormality and the compressor is stopped. 2. The condenser is provided with a condenser fan that promotes heat dissipation in the condenser, until the temperature of the refrigerant reaches the first reference temperature after the compressor is stopped. The method of detecting an abnormality in the refrigeration circuit according to claim 1, wherein the time of is measured as a second determination time, and it is determined from the second determination time whether or not an abnormality has occurred in the condenser fan. 3. The condenser is provided with a condenser fan that promotes heat radiation in the condenser, until the temperature of the refrigerant reaches the first reference temperature after the compressor is stopped. Is measured as the second determination time, the compressor is restarted when the temperature of the refrigerant reaches the first reference temperature, and after the restart, the first determination time is predetermined. The time until the compressor is stopped when the time is over,
The refrigeration circuit abnormality detection method according to claim 1, further comprising measuring as a third determination time, and determining whether or not an abnormality has occurred in the condenser fan from the second and / or third determination time.