JP5495949B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus, and more particularly to prevention of a liquid back phenomenon in which liquid refrigerant is sucked into a compressor.

  In the prior art, for example, in the “refrigeration cycle liquid back prevention device”, “a main solenoid valve is provided between the evaporator and the compressor, and the auxiliary superheater exchanges heat between the auxiliary solenoid valve and the condenser. In other words, there is a proposal that changes the refrigerant circuit by switching the two solenoid valves according to the temperature on the low-pressure side of the piping (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 47-19930 (Claim 1)

In the prior art, as a method for preventing liquid back during operation, there is a method in which a pump-down operation is performed at the time of start-up, and the refrigerant that has fallen into the low-pressure side of the refrigeration cycle (liquefied) is recovered immediately after the start of the compressor. In addition, there is one that operates at a low capacity for a certain period of time immediately after start-up to prevent rapid refrigerant inhalation. Further, a method is used in which a liquid back is detected by detecting the degree of superheat of suction and control is performed so that no liquid back is generated.
However, all of these methods are aimed at preventing liquid back immediately after starting or during operation, and a large amount of refrigerant has already fallen into the low-pressure side of the refrigeration cycle while the refrigeration system is stopped (refrigerant liquefaction). In other words, there is a problem that the liquid back cannot be effectively prevented.

In order to prevent liquid back at the time of starting the compressor, it is important to obtain the refrigerant amount on the low pressure side of the refrigeration cycle after the compressor is stopped.
However, the refrigerant state on the low-pressure side of the refrigeration cycle is a mixture of gas, liquid, or a two-phase state in which they are mixed. Become. For this reason, it is desired to easily obtain the refrigerant amount on the low pressure side of the refrigeration cycle even when the refrigerant state on the low pressure side changes after the refrigeration apparatus is stopped.

The present invention has been made to solve the above-described problems, and provides a refrigeration apparatus capable of preventing a liquid back phenomenon in which liquid refrigerant is sucked into a compressor.
Further, the present invention provides a refrigeration apparatus that can easily determine the amount of refrigerant on the low pressure side of the refrigeration cycle.

  A refrigeration apparatus according to the present invention is a refrigeration apparatus having a refrigeration cycle in which a compressor, a condenser, a decompression unit, and an evaporator are sequentially connected to circulate a refrigerant, and is provided between the condenser and the decompression unit. A provided receiver; a liquid amount detecting means for detecting the amount of refrigerant stored in the receiver; and a high pressure side refrigerant detection for detecting a refrigerant pressure and a refrigerant temperature on a high pressure side of a refrigeration cycle from the compressor to the pressure reducing means. A refrigerant amount on the high-pressure side of the refrigeration cycle is determined based on the means, the refrigerant amount stored in the receiver, and the refrigerant temperature and refrigerant pressure on the high-pressure side. Liquid back determination means for determining the presence or absence of liquid back to the compressor based on the total amount of refrigerant charged in the refrigeration cycle.

  According to the present invention, the refrigerant amount on the high pressure side of the refrigeration cycle is obtained based on the refrigerant amount stored in the receiver, the refrigerant temperature and the refrigerant pressure on the high pressure side, the refrigerant amount on the high pressure side, and a preset refrigeration cycle Whether or not the liquid back to the compressor is generated is determined based on the total amount of the refrigerant filled in the compressor. For this reason, the liquid back phenomenon can be prevented.

It is a figure which shows the structure of the refrigerating cycle of the freezing apparatus which concerns on Embodiment 1 of this invention. It is a figure explaining the division | segmentation of the refrigerant | coolant amount in the refrigerating cycle of FIG. It is a flowchart of the operation control which prevents the liquid back which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the refrigerating cycle of the freezing apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the refrigerating cycle of the freezing apparatus which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
1 is a diagram showing a configuration of a refrigeration cycle of a refrigeration apparatus according to Embodiment 1 of the present invention.
As shown in FIG. 1, the refrigeration apparatus in the present embodiment includes a compressor 1, a condenser 2, a receiver 3, a main liquid solenoid valve 5, an expansion valve 6, an evaporator 7, and an accumulator 8 sequentially connected by a connecting pipe. The refrigeration cycle for circulating the refrigerant is configured.
A liquid dropping tube 9 is connected to the bottom of the accumulator 8, and is connected to the receiver 3 via a refrigerant amount adjusting electromagnetic valve 10 and a refrigerant check valve 11.
Furthermore, the upper part of the accumulator 8 and the upper part of the receiver 3 are connected by a pressure equalizing pipe 12 via a pressure equalizing solenoid valve 13.

The “expansion valve 6” corresponds to the “pressure reducing means” in the present invention.
The “refrigerant amount adjusting electromagnetic valve 10” corresponds to the “second on-off valve” in the present invention.
The “pressure equalizing solenoid valve 13” corresponds to the “first on-off valve” in the present invention.

In addition, a pressure sensor P and a temperature sensor T that constitute high-pressure side refrigerant detection means for detecting refrigerant pressure and refrigerant temperature on the high-pressure side of the refrigeration cycle from the compressor 1 to the expansion valve 6 are provided in each part.
The pressure sensor P1 detects the pressure of the refrigerant discharged from the compressor 1.
The temperature sensor T1 detects the temperature of the refrigerant discharged from the compressor 1.
The pressure sensor P2 detects the pressure of the refrigerant in the condenser 2.
The temperature sensor T2 detects the temperature of the refrigerant in the condenser 2.
The temperature sensor T4 detects the temperature of the refrigerant in the receiver 3.
The temperature sensor T <b> 5 detects the temperature of the refrigerant in the pipe connecting the receiver 3 and the main liquid solenoid valve 5. That is, the temperature sensor T5 detects the temperature of the refrigerant from the receiver 3 to the expansion valve 6. Note that the temperature of the refrigerant between the main liquid solenoid valve 5 and the expansion valve 6 may be detected instead of the temperature sensor T5.

The liquid level sensor 4 detects the liquid level of the refrigerant stored in the receiver 3.
The liquid level sensor 4 constitutes a liquid amount detection unit that detects the amount of refrigerant stored in the receiver 3. The liquid amount detection means obtains the refrigerant amount stored in the receiver 3 based on the liquid level, the temperature of the refrigerant in the receiver 3, and the internal volume of the receiver 3. Details will be described later.
The “liquid level sensor 4” corresponds to “liquid level detecting means” in the present invention.

The control means 20 is constituted by a microcomputer, for example, and receives detection signals from the pressure sensors P and temperature sensors T and detection signals from the liquid level sensor 4. The control means 20 controls the operation of the compressor 1, the opening degree of the refrigerant amount adjusting electromagnetic valve 10, and the opening and closing of the pressure equalizing electromagnetic valve 13.
Further, the control means 20 obtains the refrigerant amount on the high-pressure side of the refrigeration cycle based on the refrigerant amount stored in the receiver 3, the refrigerant temperature and the refrigerant pressure on the high-pressure side, and sets the refrigerant amount on the high-pressure side in advance. Whether or not a liquid back to the compressor 1 has occurred is determined based on the total amount of refrigerant charged in the refrigeration cycle. Details will be described later.

  The “control unit 20” includes the function of the “liquid back determination unit” in the present invention.

  The notification means 21 is constituted by, for example, a speaker, a buzzer, a lamp, a liquid crystal panel, and the like, and notifies an alarm or the like according to an instruction from the control means 20.

  Although not shown, each of the condenser 2 and the evaporator 7 is provided with a blower, which promotes and adjusts heat exchange with air.

First, the operation | movement at the time of the driving | operation in the freezing apparatus comprised in this way is demonstrated.
The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 2, condenses in the condenser 2 to become a high-pressure liquid refrigerant, and is stored in the receiver 3. The high-pressure liquid refrigerant accumulated in the receiver 3 is reduced in pressure by the expansion valve 6 via the main liquid electromagnetic valve 5 and becomes a low-pressure two-phase refrigerant. This low-pressure two-phase refrigerant evaporates in the evaporator 7 to become a low-pressure gas refrigerant, and is again sucked into the compressor 1 via the accumulator 8 that stores excess refrigerant. At this time, the refrigerant quantity adjusting solenoid valve 10 and the pressure equalizing solenoid valve 13 are closed.
Next, an operation for preventing the liquid back phenomenon in which the liquid refrigerant is sucked into the compressor 1 will be described.

(Outline of liquid back judgment)
The refrigeration apparatus in the present embodiment estimates the amount of refrigerant on the high-pressure side of the refrigeration cycle from the compressor 1 to the expansion valve 6 to estimate the amount of refrigerant on the low-pressure side from the expansion valve 6 to the compressor 1. The possibility of liquid back is determined based on the amount of refrigerant on the low pressure side.
Thus, by obtaining the amount of refrigerant on the high pressure side and estimating the amount of refrigerant on the low pressure side, for example, the operation of the refrigeration cycle is stopped and the refrigerant state (gas, liquid or two-phase state) in each component on the low pressure side Even if is changed, it is possible to calculate the refrigerant amount. Further, for example, even if the refrigeration apparatus does not have an evaporator, an expansion valve, or the like unlike a condensing unit and the amount of refrigerant on the low pressure side varies depending on the connected evaporator or refrigerant pipe, It is possible to estimate the refrigerant amount on the side.
A specific example of determining whether or not a liquid bag has occurred will be described below.

FIG. 2 is a diagram for explaining the refrigerant amount classification in the refrigeration cycle of FIG.
As shown in FIG. 2, for example, the amount of refrigerant in each part of the refrigeration cycle is defined as follows.
M1: Refrigerant amount in the pipe between the compressor 1 outlet and the condenser 2 inlet M2: Refrigerant amount in the condenser 2 M3: Refrigerant amount in the pipe between the condenser 2 outlet and the receiver 3 M4: Refrigerant amount in the receiver 3 M5: Refrigerant amount of piping between receiver 3 outlet and main liquid solenoid valve 5 inlet M6: Refrigerant amount of piping between main liquid solenoid valve 5 outlet and expansion valve 6 inlet M7: Low pressure side refrigerant amount Compressor 1, condensation Let M be the total amount of refrigerant in the refrigeration cycle composed of the vessel 2, the receiver 3, the expansion valve 6, the evaporator 7, the accumulator 8, and the piping connecting them. Note that the value of the total refrigerant amount M is preset in the design stage, for example.

At this time, the relationship between the total refrigerant amount M and M1 to M7 is expressed by the following formula 1.
M = M1 + M2 + M3 + M4 + M5 + M6 + M7 (Formula 1)

By transforming this into the following formula 2, the low-pressure-side refrigerant amount M7 is obtained.
At this time, the total amount of refrigerant on the high pressure side is set to MH.
M7 = M− (M1 + M2 + M3 + M4 + M5 + M6) = M−MH (Formula 2)

Since M is the total amount of refrigerant in the refrigeration cycle, M always has a constant value.
Here, the maximum value ML of the low-pressure side refrigerant amount that does not cause liquid back is arbitrarily set by the internal volume of the accumulator 8 or the like. When M7 exceeds ML, that is, when the relationship of the following expression 3 is satisfied, the amount of refrigerant on the low pressure side becomes excessive, and it is necessary to prevent liquid back.

  M7 = M−MH> ML (Formula 3)

At this time, since M always has a constant value, the above Equation 3 is expressed by the following Equation 4.
M-ML> MH (Formula 4)
That is, when MH falls below M-ML, it can be considered that prevention of liquid back is necessary.

Next, the total amount MH of the refrigerant amount on the high pressure side is considered.
As described above, MH is expressed by Equation 5 below.
MH = M1 + M2 + M3 + M4 + M5 + M6 (Formula 5)

The following can be said about M1 to M6.
M1, M2, M3, M5, and M6 can be estimated using the pressure and temperature at each site.
That is, the refrigerant quantity can be calculated by converting the refrigerant temperature and the refrigerant pressure of each part into the density of the refrigerant and multiplying the volume in the equipment or the pipe constituting the relevant part.
Regarding the calculation of M3, M5, and M6, since the refrigerant in the part is in a saturated liquid state, the influence of the pressure on the density is negligibly small, and the density of the refrigerant is almost determined by the temperature. For this reason, the density of the refrigerant | coolant of the said site | part may be calculated using temperature, and you may make it ignore a pressure.

Since the liquid level height of the receiver 3 changes depending on the operation state, the liquid level height of the receiver 3 is measured by the liquid level sensor 4, and the M4 is measured by the refrigerant density in the receiver 3 and the internal volume of the receiver 3. Can be estimated.
That is, the refrigerant amount in the receiver 3 can be calculated by converting the refrigerant temperature and refrigerant pressure into the refrigerant density and multiplying the volume of the liquid refrigerant calculated from the cross-sectional area of the receiver 3 and the liquid level.
Since the refrigerant in the saturated liquid state is stored in the receiver 3, as described above, the density of the refrigerant may be calculated using only the temperature and the pressure may be ignored.

From the above, the control means 20 in the present embodiment, based on the refrigerant amount (M4) stored in the receiver 3, and the refrigerant temperature and refrigerant pressure on the high pressure side, the refrigerant amount (MH on the high pressure side of the refrigeration cycle). ) And the presence or absence of occurrence of liquid back to the compressor 1 is determined based on the refrigerant amount (MH) on the high-pressure side and the total amount (M) of the refrigerant amount charged in the preset refrigeration cycle. .
Next, an operation control operation for preventing liquid back will be described.

(Liquid back prevention operation)
FIG. 3 is a flowchart of operation control for preventing liquid back according to the first embodiment of the present invention.
Hereinafter, a description will be given based on each step of FIG.

(S10)
As described above, the control unit 20 obtains the refrigerant amounts M1 to M6 in the respective components on the high-pressure side from the current detection values of the sensors, and obtains the total amount MH of the refrigerant amount on the high-pressure side. Next, the refrigerant amount (MH) on the high pressure side is subtracted from the total amount (M) of the refrigerant charged in the refrigeration cycle to obtain the refrigerant amount (M7) on the low pressure side from the expansion valve 6 to the compressor 1. Ask. Then, it is determined whether or not the liquid back to the compressor 1 is generated by determining whether or not the refrigerant amount (M7) on the low-pressure side exceeds a preset upper limit (ML).
When it is determined that there is no occurrence of liquid back to the compressor 1, the operation shifts to normal operation control of the refrigeration apparatus. Even after the shift to the normal operation control, the main flow operation for preventing liquid back may be performed constantly or periodically.

  Here, the upper limit value (ML) is set according to the volume of the accumulator 8 provided between the evaporator 7 and the compressor 1. Note that the value of the upper limit value is not limited to this, and may be set according to the volume in each component on the low pressure side from the expansion valve 6 to the compressor 1 and in the connection pipe.

Further, here, a case will be described in which the amount of refrigerant on the low pressure side (M7) is obtained and compared with the upper limit value (ML) to determine whether or not liquid back has occurred, but the method for determining liquid back is not limited to this. is not. For example, if the refrigerant amount (M4) stored in the high-pressure side receiver 3 has the largest influence on the low-pressure side refrigerant amount (M7) and the refrigerant amount (M4) stored in the receiver 3 is small, the low pressure In view of the relationship that the refrigerant amount (M7) on the side becomes relatively large, the possibility of liquid back may be determined based on the refrigerant amount (M4) in the receiver 3.
For example, the lower limit value of the refrigerant amount (M4) stored in the receiver 3 is set according to the total amount (M) of the filled refrigerant amount and the upper limit value (ML) on the low pressure side, and the current receiver 3 When the liquid level is equal to or lower than the appropriate liquid level calculated from the refrigerant temperature, it may be determined that the amount of refrigerant on the low-pressure side (M7) is excessive, and the occurrence of liquid back is determined.

(S11)
When it is determined in step S10 that the liquid back to the compressor 1 has occurred, the control means 20 determines whether or not the refrigeration cycle of the refrigeration apparatus is in an operating state.

(S12)
When not in the operating state, the control means 20 puts the compressor 1 into a start standby state (a state in which the start is prohibited).

(S13)
Next, the control means 20 opens the pressure equalizing solenoid valve 13 to increase the pressure in the accumulator 8, opens the refrigerant amount adjusting solenoid valve 10, and opens the refrigerant in the accumulator 8 to check the refrigerant. Move to the receiver 3 via the valve 11. Thereby, the refrigerant | coolant amount (M7) of a low voltage | pressure side reduces.
The open state of the pressure equalizing solenoid valve 13 and the refrigerant amount adjusting solenoid valve 10 may be continued until it is determined in step S14, which will be described later, that no liquid back has occurred, and is closed after a predetermined time has elapsed. You may make it return.

(S14)
The control means 20 determines whether or not a liquid back has occurred in the compressor 1 as in step S10. If it is determined that liquid back has occurred, the process returns to step S12 and the above-described operation is repeated.

(S15)
On the other hand, when it is determined that there is no liquid back, the control unit 20 brings the compressor 1 into a startable state.

(S16)
When it is necessary to start the compressor 1 due to the operating state of the refrigeration cycle, the compressor 1 is started.
Thereafter, the operation shifts to normal operation control of the refrigeration apparatus. Even after the shift to the normal operation control, the main flow operation for preventing liquid back may be performed constantly or periodically.

(S17)
When it is determined in step S11 that the engine is in operation, that is, it is determined that liquid back has occurred in the compressor 1, and the refrigeration cycle is in operation, the control unit 20 causes the notification unit 21 to generate liquid back. Alerts that there is a possibility of doing so.

(S18)
Next, the control means 20 detects the pressure and temperature of the refrigerant sucked into the compressor 1 by a pressure sensor and a temperature sensor (not shown) provided in the vicinity of the suction port of the compressor 1, and the refrigeration Determine the degree of superheat (SH) of the cycle. And it is judged whether the calculated | required superheat degree is smaller than predetermined value.
If the degree of superheat is greater than the predetermined value, the process returns to step S10 and the above operation is repeated.

  Thus, even when it is determined that there is a possibility of occurrence of liquid back, the operation state is continued if the degree of superheat in the operation state is large. This is because even if the amount of refrigerant on the low-pressure side (M7) is large, if the degree of superheat is large, the compressor 1 is unlikely to suck liquid or two-phase refrigerant, and liquid back is possible. This is because the nature is low.

(S19)
On the other hand, when the degree of superheat is smaller than the predetermined value in step S18, the control means 20 stops (temporarily stops) the operation of the compressor 1. Thereby, the liquid back to the compressor 1 is prevented.
At this time, the control means 20 counts the number of times the compressor 1 is stopped.

(S20)
Next, the control means 20 determines whether or not the number of times the compressor 1 has been stopped in step S19 is less than or equal to a predetermined set value.
When the number of times the compressor 1 is stopped is equal to or less than the predetermined set value, the process proceeds to step S12 and the above-described operation is performed.

  Here, a case will be described in which it is determined that the refrigeration unit is abnormal when the number of stops of the compressor 1 is equal to or greater than a set value. However, the present invention is not limited to this, and an alarm in step S17 is provided. The number of times of reporting may be counted, and if the reporting is repeated more than a predetermined number of times, it may be determined as abnormal.

(S21)
If it is determined in step S20 that the number of times the compressor 1 has been stopped is not less than a predetermined set value, the control means 20 determines that the refrigeration apparatus is abnormal, abnormally stops the operation of the refrigeration cycle, and ends the operation. To do.

As described above, in the present embodiment, the refrigerant amount (MH) on the high-pressure side of the refrigeration cycle is obtained based on the refrigerant amount (M4) stored in the receiver 3 and the refrigerant temperature and refrigerant pressure on the high-pressure side. Based on the refrigerant amount (MH) on the high-pressure side and the total amount (M) of the refrigerant amount charged in the preset refrigeration cycle, it is determined whether or not the liquid back to the compressor 1 is generated.
For this reason, even if it is a case where the refrigerant | coolant state by the side of a low pressure changes after the refrigerating device stops, it can be determined whether the liquid back to the compressor 1 has occurred. Accordingly, it is possible to prevent the liquid back from being sucked into the compressor by the liquid refrigerant.

Further, the refrigerant amount (MH) on the low pressure side from the expansion valve 6 to the compressor 1 is obtained by subtracting the refrigerant amount (MH) on the high pressure side from the total amount (M) of the refrigerant charged in the refrigeration cycle. When the refrigerant amount (M7) on the low pressure side exceeds a preset upper limit (ML), it is determined that the liquid back to the compressor 1 has occurred.
For this reason, even if the refrigerant state on the low-pressure side changes after the refrigeration system is stopped, the amount of refrigerant on the low-pressure side of the refrigeration cycle can be easily obtained, and it is determined whether or not liquid back to the compressor 1 has occurred. can do. Accordingly, it is possible to prevent the liquid back from being sucked into the compressor by the liquid refrigerant.

The upper limit value is set according to the volume in each component on the low pressure side from the expansion valve 6 to the compressor 1 and in the connection pipe. Alternatively, the upper limit value is set according to the volume of the accumulator 8 provided between the evaporator 7 and the compressor 1.
For this reason, when the liquid refrigerant on the low pressure side is excessive, it can be determined that the liquid back has occurred. Accordingly, it is possible to prevent the liquid back from being sucked into the compressor by the liquid refrigerant.

Further, the amount of refrigerant in each component and connection pipe is obtained based on the volume in each component and connection pipe on the high-pressure side of the refrigeration cycle, and the pressure and temperature of the refrigerant in each component and connection pipe. .
For this reason, the total amount of the high-pressure side refrigerant can be obtained with high accuracy. Therefore, the occurrence of liquid back can be determined with high accuracy, and liquid back to the compressor can be prevented.

Moreover, it has the liquid level sensor 4 which detects the liquid level height of the refrigerant | coolant stored by the receiver 3, and is based on the liquid level height, the temperature of the refrigerant | coolant in the receiver 3, and the internal volume of the receiver 3. The amount of refrigerant (M4) stored in 3 is obtained.
For this reason, the refrigerant | coolant amount (M4) stored in the receiver 3 can be calculated | required accurately. Therefore, the occurrence of liquid back can be determined with high accuracy, and liquid back to the compressor can be prevented.

When the operation of the refrigeration cycle is stopped, when it is determined that the liquid back to the compressor 1 has occurred, the pressure equalizing solenoid valve 13 is opened to increase the pressure in the accumulator 8 to adjust the amount of refrigerant. The electromagnetic valve 10 is opened and the refrigerant in the accumulator 8 is moved to the receiver 3.
For this reason, a part of low-pressure side refrigerant can be returned to the high-pressure side, and the amount of low-pressure side liquid refrigerant can be reduced. Therefore, even when the compressor 1 is started from a state in which a large amount of refrigerant has already fallen on the low-pressure side of the refrigeration cycle (a state in which the refrigerant is liquefied) while the refrigeration apparatus is stopped, the liquid to the compressor 1 Back can be prevented.

Further, when it is determined that there is a liquid back to the compressor 1 when the refrigeration cycle is in operation, the operation of the compressor 1 is stopped.
For this reason, the liquid back | bag to a compressor can be prevented.

Further, when it is determined that there is a liquid back to the compressor 1 when the refrigeration cycle is in an operating state, the notification means 21 notifies that a liquid back is generated.
For this reason, when the liquid back to a compressor arises, it can alert | report.

Further, when it is determined that there is no liquid back to the compressor 1 when the operation of the refrigeration cycle is stopped, the compressor 1 is brought into a startable state.
For this reason, the compressor 1 can be started when the possibility of occurrence of liquid back is low.

Embodiment 2. FIG.
FIG. 4 is a diagram showing the configuration of the refrigeration cycle of the refrigeration apparatus according to Embodiment 2 of the present invention.
As shown in FIG. 4, in the refrigeration apparatus in the second embodiment, the evaporator 7 and the compressor 1 are directly connected, the accumulator 8 described in the first embodiment, and the liquid drop tube connected to the accumulator 8. 9 and the pressure equalizing pipe 12, and the refrigerant quantity adjusting electromagnetic valve 10, the refrigerant check valve 11, and the pressure equalizing electromagnetic valve 13 are not provided.
Other configurations are the same as those of the first embodiment (FIG. 1), and the same portions are denoted by the same reference numerals.

As described above, regardless of the presence or absence of the accumulator 8, the total amount (MH) of the high-pressure side refrigerant amount is obtained and the total amount (MH) of the high-pressure side refrigerant amount is obtained from the total refrigerant amount (M). Is subtracted to calculate the refrigerant amount (M7) on the low pressure side.
Then, the upper limit value (ML) set according to the volume in each component on the low pressure side from the expansion valve 6 to the compressor 1 and in the connection pipe is compared with the amount of refrigerant on the low pressure side (M7). When> ML, it is determined that liquid back has occurred.
Even in such a configuration, the same effects as those of the first embodiment can be obtained.

Embodiment 3 FIG.
FIG. 5 is a diagram showing the configuration of the refrigeration cycle of the refrigeration apparatus according to Embodiment 3 of the present invention.
As shown in FIG. 5, the refrigeration apparatus in the third embodiment has a configuration in which the liquid level sensor 4 described in the first embodiment is not provided.
In addition to the configuration of the first embodiment (FIG. 1), a pressure sensor P3 for detecting the refrigerant pressure at the inlet of the receiver 3 and a pressure sensor P5 for detecting the refrigerant pressure at the outlet of the receiver 3 are provided.
Other configurations are the same as those of the first embodiment (FIG. 1), and the same portions are denoted by the same reference numerals.

In the third embodiment, the liquid level of the receiver 3 is calculated from the differential pressure of the refrigerant pressure at the inlet / outlet of the receiver 3. Then, similarly to the first embodiment, the refrigerant amount (M4) stored in the receiver 3 is obtained based on the liquid level and the refrigerant temperature in the receiver 3.
Other operations are the same as those in the first embodiment.
Even in such a configuration, the same effects as those of the first embodiment can be obtained.

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Condenser, 3 Receiver, 4 Liquid level sensor, 5 Main liquid solenoid valve, 6 Expansion valve, 7 Evaporator, 8 Accumulator, 9 Liquid drop pipe, 10 Refrigerant amount adjustment solenoid valve, 11 Refrigerant reverse Stop valve, 12 pressure equalizing pipe, 13 pressure equalizing solenoid valve, 20 control means, 21 informing means, P pressure sensor, T temperature sensor.

Claims (10)

A refrigeration apparatus having a refrigeration cycle in which a compressor, a condenser, a decompression unit, and an evaporator are sequentially connected to circulate a refrigerant,
A receiver provided between the condenser and the pressure reducing means;
Liquid amount detecting means for detecting the amount of refrigerant stored in the receiver;
High-pressure side refrigerant detection means for detecting refrigerant pressure and refrigerant temperature on the high-pressure side of the refrigeration cycle from the compressor to the decompression means;
Based on the refrigerant quantity stored in the receiver and the refrigerant temperature and refrigerant pressure on the high pressure side, the refrigerant quantity on the high pressure side of the refrigeration cycle is obtained, and the refrigerant quantity on the high pressure side and the preset refrigeration cycle A refrigerating apparatus comprising: a liquid back determining means for determining whether or not a liquid back has occurred in the compressor based on a total amount of refrigerant filled in the compressor. The liquid back determination means
Subtracting the amount of refrigerant on the high-pressure side from the total amount of refrigerant charged in the refrigeration cycle to determine the amount of refrigerant on the low-pressure side from the decompression means to the compressor;
2. The refrigeration apparatus according to claim 1, wherein when the amount of refrigerant on the low pressure side exceeds a preset upper limit value, it is determined that a liquid back to the compressor is generated. 3. The refrigeration apparatus according to claim 2, wherein the upper limit value is set according to a volume in each component on the low pressure side from the decompression means to the compressor and in a connection pipe. The refrigerating apparatus according to claim 2, wherein the upper limit value is set according to a volume of an accumulator provided between the evaporator and the compressor. The high-pressure side refrigerant detection means includes
At least the pressure and temperature of the refrigerant discharged from the compressor, the pressure and temperature of the refrigerant in the condenser, the temperature of the refrigerant in the receiver, and the temperature of the refrigerant from the receiver to the decompression means are detected. Having a sensor,
The liquid back determination means
Based on the volume in each component on the high-pressure side of the refrigeration cycle and in the connection pipe, and the pressure and temperature of the refrigerant in each component and in the connection pipe, the amount of refrigerant in each component and in the connection pipe is determined,
The refrigerant amount on the high-pressure side of the refrigeration cycle is obtained based on the refrigerant amount in each component on the high-pressure side of the refrigeration cycle and in the connection pipe, and the refrigerant amount stored in the receiver. The refrigeration apparatus of any one of -4. The liquid amount detecting means includes
A liquid level detecting means for detecting a liquid level height of the refrigerant stored in the receiver;
The amount of refrigerant stored in the receiver is obtained based on the liquid level, the temperature of the refrigerant in the receiver, and the internal volume of the receiver. The refrigeration apparatus described. An accumulator provided at a position higher than the receiver between the evaporator and the compressor;
A pressure equalizing pipe communicating the accumulator and the receiver through a first on-off valve;
A liquid drop pipe for guiding the refrigerant stored in the accumulator to the receiver;
A second on-off valve for opening and closing the flow path of the liquid dropping pipe,
The liquid back determination means
When the operation of the refrigeration cycle is stopped, when it is determined that there is a liquid back to the compressor,
2. The first on-off valve is opened to increase the pressure in the accumulator, and the second on-off valve is opened to move the refrigerant in the accumulator to the receiver. The refrigeration apparatus of any one of -6. The liquid back determination means
8. The operation of the compressor according to claim 1, wherein when the refrigeration cycle is in an operating state, the operation of the compressor is stopped when it is determined that liquid back to the compressor is generated. Refrigeration equipment. Providing a notification means,
The liquid back determination means
9. The system according to claim 1, wherein, when the refrigeration cycle is in an operating state, when it is determined that liquid back has occurred in the compressor, the notification means notifies that a liquid back is generated. The refrigeration apparatus according to claim 1. The liquid back determination means
10. The compressor according to claim 1, wherein when the operation of the refrigeration cycle is stopped, when it is determined that there is no liquid back to the compressor, the compressor is allowed to start. The refrigeration apparatus according to item.

Images