JP3296107B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system capable of detecting a gas shortage.

[0002]

2. Description of the Related Art Conventionally, some refrigeration systems detect gas shortage when an input current of a compressor falls below a set value corresponding to an operation frequency. That is, as shown in FIG.
The set value corresponding to the operating frequency of the compressor is represented by: set value = AG1 × FOUT + BG1 (FOUT: operating frequency, AG1, BG1: constant), below the straight line represented by the above equation and at a predetermined value. The region from the operating frequency FGAS to the upper limit of the operating frequency is defined as a gas-out zone.

[0003]

By the way, as shown in FIG. 5, when the gas deficiency increases,
The straight line representing the input current characteristic with respect to the operating frequency of the compressor moves downward. For example, at the frequency a, the input current of the compressor gradually decreases as the amount of gas depletion increases. As shown in FIG. 6, the characteristics of the input current with respect to the refrigerant amount vary depending on the operating state (operating frequency). Even when the set value of the input current for detecting the lack of gas is the same, when the operating frequency is high, , Refrigerant amount is about 10
%, Whereas when the operating frequency is low, the lack of gas is detected at about 70% of the refrigerant amount that does not hinder the operation. For this reason, when the refrigerant amount is large, it is necessary to reduce the set value of the input current for detecting the lack of gas so as not to detect the lack of gas. However, when the set value is reduced in this manner, there is a disadvantage that the gas shortage cannot be detected unless the gas is completely exhausted.

An object of the present invention is to provide a refrigeration apparatus that can detect a gas shortage early before the gas shortage occurs completely.

[0005]

In order to achieve the above object, a refrigeration apparatus according to claim 1 is connected to a compressor, a condenser, an evaporator, and between the condenser and the evaporator. Expansion means, a first temperature sensor for detecting a measured discharge pipe temperature of the compressor, a second temperature sensor for detecting a condensation temperature of the condenser, and a third temperature sensor for detecting an evaporation temperature of the evaporator. In the refrigerating apparatus provided with, the superheat degree becomes constant based on the condensation temperature detected by the second temperature sensor and the evaporation temperature detected by the third temperature sensor .
A target discharge pipe temperature calculation means for calculating a sea urchin target discharge pipe temperature, the said measured discharge pipe temperature detected by the first sensor is based on the above target discharge pipe temperature calculated by the target discharge pipe temperature calculation section A gas lack determining means for determining that the gas is missing when the calculated reference value exceeds the reference value for detecting the lack of gas.

The refrigeration apparatus according to a second aspect of the present invention is the refrigeration apparatus according to the first aspect, further comprising input current detection means for detecting an input current of the compressor, and wherein the gas shortage determination means is provided with the input current detection means. When the input current detected by the above is less than or equal to a predetermined value corresponding to the operating frequency of the compressor, it is determined that there is no gas.

According to a third aspect of the present invention, there is provided the refrigeration apparatus according to the first or second aspect, wherein the expansion means is an electric valve, and the electric valve is arranged so that a discharge pipe temperature of the compressor becomes substantially constant. A gas valve control means for controlling the degree of superheat by opening and closing the valve, wherein the gas-out-of-gas determining means is adapted to allow the measured discharge pipe temperature to exceed the reference value based on the target discharge pipe temperature and to open the electric valve. Is determined to be out of gas when the opening degree is equal to or greater than a predetermined opening degree.

The refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to any one of the first to third aspects, further comprising timer means for measuring a predetermined time.
When the state of the gas shortage continues for the predetermined time or more by the timer means, it is determined that there is a gas shortage.

[0009]

According to the refrigerating apparatus of the first aspect, the target discharge pipe temperature calculating means calculates the target discharge pipe temperature based on the condensation temperature detected by the second temperature sensor and the evaporation temperature detected by the third temperature sensor. The target discharge pipe temperature is calculated so that the degree of superheat is constant . Then, the gas shortage determining means, said the actual discharge pipe temperature detected by the first sensor for gas shortage detection determined based on the target discharge pipe temperature calculated by the target discharge pipe temperature calculation section If it exceeds the reference value, it is determined that the gas is out. Therefore, when the amount of the refrigerant decreases, the amount of circulation of the refrigerant decreases, so that the overheating is excessive, and the measured discharge pipe temperature of the compressor increases.
Even if it is not completely out of gas, it can be determined that there is no gas in a wide range in which the amount of refrigerant is reduced. In addition, it is possible to detect gas shortage at an early stage when the amount of refrigerant is reduced before completely running out of gas, and it is possible to prevent operation with insufficient capacity due to gas shortage.

[0010] According to the refrigeration apparatus of the second aspect,
2. The refrigeration apparatus according to claim 1, further comprising input current detection means for detecting an input current of said compressor, wherein said lack of gas determining means operates said compressor by detecting said input current detected by said input current detection means. When the value is equal to or less than a predetermined value corresponding to the frequency, it is determined that there is no gas. For example, even if the measured discharge pipe temperature does not rise so much because the amount of refrigerant is too small from the beginning, and the measured discharge pipe temperature does not exceed the reference value based on the target discharge pipe temperature, the input current of the compressor will not exceed the operating frequency. It is possible to detect gas shortage by monitoring whether or not it is equal to or less than a predetermined value corresponding to.

According to the refrigeration apparatus of the third aspect,
3. The refrigeration apparatus according to claim 1, wherein the motor-operated valve control means performs superheat control by opening and closing the motor-operated valve so that the discharge pipe temperature of the compressor becomes substantially constant. When the measured discharge pipe temperature exceeds the target discharge pipe temperature and the opening of the electric valve is equal to or more than a predetermined opening, the gas-out-of-gas determining means determines that there is a gas shortage. That is, when the electric valve is controlled to open and close by the electric valve control means, even if the measured discharge pipe temperature exceeds the target discharge pipe temperature, if the opening of the electric valve is less than the predetermined opening, the refrigerant is It is not determined that there is sufficient gas and that there is no gas. Therefore,
In a refrigeration system that performs superheat control by making the discharge pipe temperature substantially constant by opening and closing the electric valve, when the measured discharge pipe temperature exceeds the target discharge pipe temperature, when the electric valve is less than the predetermined opening degree, While it is determined that there is no gas shortage in the operating state, if the motor-operated valve is opened to a predetermined opening degree or more and overheating is excessive, it is determined that there is a gas shortage. Therefore, the gas shortage can be accurately determined.

Further, according to the refrigeration apparatus of the fourth aspect,
The refrigeration apparatus according to any one of claims 1 to 3, further comprising timer means for measuring a predetermined time, wherein the gas shortage determination means determines whether the gas shortage state continues for a predetermined time or more by the timer means. Is determined to be out of gas.
Therefore, even if the condition of a gas shortage occurs transiently depending on the operation state, it is not immediately determined that there is a gas shortage, and erroneous gas shortage detection can be prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The refrigerating apparatus of the present invention will be described below in detail with reference to an embodiment.

FIG. 1 is a circuit diagram of an air conditioner as a refrigeration apparatus according to one embodiment of the present invention.
Is a four-way valve connected to the compressor 1, and 3 is an outdoor heat exchanger as a condenser having one end connected to the four-way valve 2, 4A, 4B,
4C is a branch line 10A, 1 at the other end of the outdoor heat exchanger 3.
The motor-operated valves 5A, 5B, and 5C each having one end connected to each other via OB and 10C are evaporators each having one end connected to the other end of each of the motor-operated valves 4A, 4B, and 4C via a line 11. Indoor heat exchanger. The indoor heat exchangers 5A, 5B,
The other end of 5C is line 12, branch lines 13A, 13B, 13C
Is connected to the four-way valve 2. The suction side of the compressor 1 and the four-way valve 2 are connected by a line 14, and the accumulator 6 is disposed on the line 14.

The air conditioner has a first temperature sensor 21 for detecting a measured discharge pipe temperature of the compressor 1 and a second temperature sensor 22 for detecting a condensation temperature of the outdoor heat exchanger 3.
And the third temperature sensors 23, 24, 25 for detecting the evaporation temperatures of the indoor heat exchangers 5A, 5B, 5C, and the actual measurements from the first, second, and third temperature sensors 21, 22, 23, 24, 25. A control unit 7 that receives signals representing the discharge pipe temperature, the condensation temperature, and the evaporation temperature, and controls opening and closing of the electric valves 4A, 4B, and 4C.
And

The control section 7 comprises an input / output circuit and a microcomputer. The control section 7 serves as a target discharge pipe temperature calculating means for calculating a target discharge pipe temperature based on the signals representing the condensation temperature and the evaporation temperature. A discharge pipe temperature calculating unit 31 and a gas for determining whether there is a gas shortage based on the actually measured discharge pipe temperature detected by the first temperature sensor 21 and the target discharge pipe temperature calculated by the target discharge pipe temperature calculation unit 31. A gas-out-of-gas discrimination unit 32 as a gas-out discrimination unit, and a motor-operated valve as motor-operated valve control means for opening and closing the electric valves 4A, 4B, and 4C to maintain the discharge pipe temperature of the compressor 1 substantially constant and perform overheating control. The control unit includes a control unit 33 and a timer unit as timer means for measuring a predetermined time.

In the air conditioner having the above configuration, when performing the cooling operation, the compressor 1 is started with the four-way valve 2 in the switching position shown by the solid line. Then, the refrigerant discharged from the compressor 1 is circulated to the outdoor heat exchanger 3, the electric valves 4A, 4B, 4C, the indoor heat exchangers 5A, 5B, 5C, and the accumulator 6. At this time, the electric valve control unit 33 of the control unit 7
The openings of the motor-operated valves 4A, 4B, 4C are controlled so that the actually measured discharge pipe temperature detected by the first temperature sensor 21 becomes substantially constant.

FIG. 4 is a Mollier diagram in which the vertical axis is pressure and the horizontal axis is enthalpy, in which the condensing temperature and the evaporating temperature are given. The characteristic line is extended from point A, and a point that intersects the condensation temperature is set as a target discharge pipe temperature SETDO. That is, assuming that the condensation temperature detected by the second temperature sensor 22 is DC and one of the evaporation temperatures detected by the third temperature sensors 23, 24, and 25 is DE, the target discharge pipe temperature SETDO is: SETDO = α × DC + β × DE + γ. The coefficients α, β, γ are determined so that the degree of superheat is constant. When the discharge pipe temperature of the compressor 1 is lower than the target discharge pipe temperature SETDO, the electric valve 4
A, 4B and 4C are closed and the discharge pipe temperature is set to the target discharge pipe temperature SET
If it is higher than DO, the motor-operated valves 4A, 4B, 4C are opened.

Then, using the target discharge pipe temperature SETDO, a reference value for detecting a lack of gas is obtained by the following equation.

Reference value = AG2 × SETDO + BG2 (AG2, BG2: constant) The gas shortage determination unit 32 of the control unit 7 determines whether the input current of the compressor 1 is equal to or less than a predetermined value corresponding to the operation frequency FOUT. At the same time, it is determined whether or not the actually measured discharge pipe temperature DO from the first temperature sensor 21 has exceeded the reference value, thereby performing a process for detecting a gas shortage.

Hereinafter, the operation of the control unit 7 for detecting the lack of gas will be described with reference to the flowchart of FIG. The process for detecting a gas shortage is repeatedly performed at predetermined intervals.

First, at step S1, it is determined whether or not the compressor 1 is operating. If it is determined that the compressor 1 is operating, the process proceeds to step S2. On the other hand, if it is determined in step S1 that the vehicle is not running, the process proceeds to step S13, where the timer TGAS1 is reset. In step S14, the timer TGAS2 is reset, and the process for detecting a gas shortage ends.

Next, at step S2, the operation frequency FOUT
Is determined to be higher than a predetermined operation frequency FGAS, and the operation frequency FOUT is determined to be higher than a predetermined operation frequency FGAS.
If it is determined that the value exceeds, the process proceeds to step S3. Then, in step S3, the input current IIN is set to the set value (AG1 ×
If it is determined that FOUT + BG1) or less, the process proceeds to step S4, where the timer TGAS1 is counted. On the other hand, in step S3, the input current IIN is set to the set value (AG1 × FOUT
If it is determined that the value exceeds + BG1), the process proceeds to step S5.

On the other hand, in step S2, the operation frequency FOUT
If the predetermined operation frequency FGAS is determined as follows, the process proceeds to step S5, resets the timer TGAS1, and proceeds to step S6.

Next, at step S6, the actually measured discharge pipe temperature DO
Is greater than the reference value (AG2 × SETDO + BG2), and the measured discharge pipe temperature DO is set to the target discharge pipe temperature (A
If it is determined that the difference has exceeded (G2 × SETDO + BG2), the process proceeds to step S7. On the other hand, if it is determined in step S6 that the actually measured discharge pipe temperature DO is equal to or less than the reference value (AG2 × SETDO + BG2), the process proceeds to step S9, and the timer TGAS2 is reset.

Next, at step S7, the electric valve opening EVMK is set.
Is determined to be equal to or greater than a predetermined opening EVGAS, and if it is determined that the motor-operated valve opening EVMK is equal to or greater than the predetermined opening EVGAS, the routine proceeds to step S8, where the timer TGAS2 is counted. On the other hand, if it is determined in step S7 that the electric valve opening EVMK is smaller than the predetermined opening EVGAS, the process proceeds to step S9, where the timer TGAS2 is reset, and the process proceeds to step S10.
Proceed to.

Then, in step S10, the timer TGAS
It is determined whether or not the count of 2 has been completed, and the timer TG
If it is determined that the counting of AS2 has been completed, step S
Proceed to step 12 to determine the gas shortage. On the other hand, step S10
When it is determined that the count of the timer TGAS2 has not ended, the process proceeds to step S11.
It is determined whether or not the counting by the timer TGAS1 has been completed, and if it is determined that the counting by the timer TGAS1 has been completed, the process proceeds to step S12, and the lack of gas is determined. On the other hand, if it is determined in step S11 that the count of the timer TGAS1 has not ended, the gas detection process ends.

As described above, the second temperature sensor 22
And the third temperature sensors 23, 24,
Evaporation temperature of any one of the evaporation temperatures detected by 25
Based on the degree DE, the target discharge pipe temperature calculator 31
The target discharge pipe temperature SETDO is calculated, and is calculated by the first sensor 21.
The detected measured discharge pipe temperature DO is the target discharge pipe temperature
Reference value based on SETDO (AG2 × SETDO + BG
2) , and when the opening EVMK of the motor-operated valves 4A, 4B, 4C is greater than or equal to a predetermined opening EVGAS, the gas-out-of-gas determining unit 32
Is determined to be out of gas. Therefore, it is possible to determine the lack of gas in a wide range in which the amount of the refrigerant is reduced, even if the lack of gas is not complete. In addition, it is possible to detect gas shortage at an early stage when the amount of the refrigerant is reduced before the gas is completely exhausted, and it is possible to prevent the operation with insufficient capacity due to the lack of gas. Furthermore, when the motor-operated valves 4A, 4B, 4C are opened to a predetermined opening EVGAS or more and overheat is applied, it can be determined that the gas is insufficient, so that the gas lack can be accurately determined.

FIG. 7 shows the relationship between the refrigerant amount and the internal temperature of the compressor 1. The internal temperature increases as the refrigerant amount decreases. The discharge temperature also rises substantially in proportion to the rise in the internal temperature of the compressor 1, but when the refrigerant amount becomes 25% or less, the discharge temperature falls because the amount of refrigerant is small. For this reason, gas shortage cannot be detected in a range where the amount of refrigerant is too small and the measured discharge pipe temperature DO does not rise. Therefore, the input current INN detected by the input current detecting unit 8 by the gas-out-of-gas determining unit 32 is used as the operating frequency FOUT of the compressor 1.
When it is equal to or less than a predetermined value according to the above, it is determined that the gas is out of gas. Therefore, for example, even when the amount of gas refrigerant is small and the measured discharge pipe temperature DO does not rise so much as when the refrigerant is zero from the beginning, the input current I
By monitoring whether NN is equal to or less than a predetermined value corresponding to the operation frequency FOUT, it is possible to detect gas shortage. The hatched area indicates an area where the compressor 1 is to be protected.

The timers TGAS1 and TGAS2 of the timer section 34 of the control section 7 exceed the reference value (AG2 × SETDO + BG2) based on the target discharge pipe temperature SETDO calculated by the target discharge pipe temperature calculation section 31, and The opening EVMK of the motor-operated valves 4A, 4B, 4C is equal to the predetermined opening E
When the state equal to or higher than VGAS continues for more than the timer time set by the timer TGAS2, or when the state of gas shortage where the input current INN is equal to or less than a predetermined value corresponding to the operating frequency FOUT of the compressor 1 continues for more than the timer time set by the timer TGAS1; The gas deficiency determination unit 32 determines that there is a gas deficiency. Therefore, depending on the operating state, even if the condition of the gas shortage detection is satisfied transiently, it is not immediately determined that the gas is low,
It is possible to prevent erroneous gas lack determination.

In the above embodiment, the refrigeration apparatus of the present invention has been described by taking an air conditioner as an example. However, it goes without saying that the refrigeration apparatus may be applied to other refrigeration apparatuses.

In the above embodiment, the motor-operated valves 4A, 4B and 4C are used as expansion means. However, the present invention is not limited to this, and the expansion means may be a capillary tube or the like.

In the above embodiment, the outdoor heat exchanger 3 is used as the condenser and the indoor heat exchangers 5A, 5B, 5C are used as the evaporator.
A heating operation may be performed, and the indoor heat exchangers 5A, 5B, and 5C may be used as condensers, and the outdoor heat exchanger 3 may be used as an evaporator.

Further, in the above embodiment, the input current detecting section 8 as the input current detecting means is provided, and the gas determining section 32 as the gas determining means is provided with the input current INN of the compressor 1.
Is determined to be equal to or greater than a predetermined value, but the input current detecting means may not be provided.

In the above embodiment, the timers TGAS1 and TGAS2 of the timer section 34 are used as timer means, but the timer means may not be provided.

[0036]

As is apparent from the above description, the refrigerating apparatus according to the first aspect of the present invention comprises a compressor, a condenser, an evaporator, and expansion means connected between the condenser and the evaporator. A first temperature sensor for detecting a measured discharge pipe temperature of the compressor, a second temperature sensor for detecting a condensation temperature of the condenser, and a third temperature sensor for detecting an evaporation temperature of the evaporator. In the refrigerating apparatus, the target discharge pipe temperature calculating means calculates the degree of superheat based on the condensation temperature detected by the second temperature sensor and the evaporation temperature detected by the third temperature sensor.
While calculating the target discharge pipe temperature so that
Gas shortage determining means, reference for gas shortage detection measured discharge pipe temperature detected by the first sensor is determined based on the target discharge pipe temperature calculated by the target discharge pipe temperature calculation section
When the value exceeds the value , it is determined that the gas is out of gas.

Therefore, according to the refrigeration apparatus of the first aspect of the present invention, it is possible to determine the lack of gas in a wide range in which the amount of refrigerant is reduced, even if the gas is not completely lacking. In addition, it is possible to detect gas shortage at an early stage when the amount of refrigerant decreases before the gas is completely run out, and it is possible to prevent operation with insufficient capacity due to gas shortage.

Further, the refrigeration apparatus according to the second aspect of the present invention is the refrigeration apparatus according to the first aspect, further comprising input current detection means for detecting an input current of the compressor, When the input current detected by the detecting means is equal to or less than a predetermined value corresponding to the operating frequency of the compressor, it is determined that the gas is out.

Therefore, according to the refrigerating apparatus of the second aspect of the present invention, for example, the measured discharge pipe temperature does not rise so much because the amount of refrigerant is too small from the beginning, and the measured discharge pipe temperature becomes the target discharge pipe temperature. Even if the reference value is not exceeded, whether the input current of the compressor is equal to or less than a predetermined value corresponding to the operation frequency can be monitored to detect gas shortage.

According to a third aspect of the present invention, in the refrigeration system of the first or second aspect, the expansion means is an electric valve, and the electric valve control means controls the discharge pipe temperature of the compressor substantially. The superheat degree control is performed by opening and closing the electric valve so as to be constant, and the gas lack determining means determines that the measured discharge pipe temperature exceeds the target discharge pipe temperature, and the electric valve opening degree determining means determines whether the electric valve opening degree is controlled by the electric valve. When the opening degree of the valve is equal to or more than a predetermined opening degree, it is determined that there is no gas.

Therefore, according to the refrigeration system of the third aspect of the present invention, in the refrigeration system that controls the degree of superheat by opening and closing the electric valve, when the measured discharge pipe temperature exceeds the target discharge pipe temperature, the motorized valve is turned off. When the opening is less than the predetermined opening, it is determined that the operating state is normal and the gas is not exhausted.On the other hand, when the electric valve is opened more than the opening and the overheating is excessive, it is determined that the gas is exhausted. it can. Therefore, the gas shortage can be accurately determined.

According to a fourth aspect of the present invention, there is provided the refrigeration apparatus according to any one of the first to third aspects, further comprising timer means for measuring a predetermined time. When the state of the gas shortage continues for the predetermined time or more by the timer means, it is determined that the gas is low.

Therefore, according to the refrigerating apparatus of the present invention, there is provided a timer means for measuring a predetermined time, and the gas-out determining means determines whether or not the gas-out state is equal to or longer than the predetermined time of the timer means. When continuing, it is determined that there is no gas. Therefore, even if the condition of a gas shortage occurs transiently depending on the operation state, it is not immediately determined that there is a gas shortage, so that erroneous gas shortage can be prevented from being detected.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a refrigeration apparatus according to one embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of a gas shortage detection process of a control unit of the refrigeration apparatus.

FIG. 3 is a view showing a gas-out zone of a compressor of the refrigeration apparatus.

FIG. 4 is a Mollier diagram of the refrigeration apparatus.

FIG. 5 is a diagram showing that the characteristics of the operating frequency and the input current of the compressor of the refrigeration apparatus change with an increase in gas shortage.

FIG. 6 is a diagram showing that the input current characteristic with respect to the refrigerant amount of the refrigeration apparatus varies depending on the operation state.

FIG. 7 is a diagram showing the relationship between the amount of refrigerant in the refrigeration apparatus and the internal temperature of the compressor.

[Explanation of symbols]

1 ... Compressor, 2 ... Four-way valve, 3 ... Outdoor heat exchanger, 4A, 4B,
4C: electric valve, 5A, 5B, 5C: indoor heat exchanger, 6: accumulator, 7: control unit, 8: input current detection unit, 21: first temperature sensor, 22: second temperature sensor, 23, 24, 25: a third temperature sensor, 31: a target discharge pipe temperature calculating section, 32: a gas shortage determining section, 33: an electric valve control section, 34: a timer section.

Claims (4)

(57) [Claims] 1. A compressor (1), a condenser (3), and an evaporator
(5A, 5B, 5C), the condenser (3), and the evaporator (5A, 5C).
B, 5C), and the compressor (1)
A first temperature sensor (21) for detecting an actually measured discharge pipe temperature of
A second temperature sensor for detecting the condensation temperature of the condenser (3)
(22) and a third temperature sensor (23, 24, 25) for detecting the evaporating temperature of the evaporator (5A, 5B, 5C), wherein the temperature is detected by the second temperature sensor (22). A target discharge pipe temperature calculation for calculating a target discharge pipe temperature (SETDO) such that the degree of superheat is constant based on the condensed temperature and the evaporation temperature detected by the third temperature sensor (23, 24, 25). and means (31), the detected the actual discharge pipe temperature by the first sensor (21) (DO) is the calculated the target discharge pipe temperature (SETDO) by the target discharge pipe temperature calculation section (31) based on Dzu doctor
Reference value for the gas lack detection obtained Te (AG2 × SETD
A refrigerating apparatus comprising: a gas shortage determining means (32) for determining that the gas is low when exceeding O + BG2). 2. A refrigerating apparatus according to claim 1, wherein input current detecting means for detecting an input current of said compressor (1).
(8) the gas shortage determination means (32) is provided when the input current detected by the input current detection means (8) is equal to or less than a predetermined value corresponding to an operating frequency of the compressor (1). A refrigerating apparatus for determining that the gas is out of gas. 3. The refrigeration apparatus according to claim 1, wherein the expansion means is a motor-operated valve (4A, 4B, 4C),
An electric valve control means (33) for opening and closing the electric valves (4A, 4B, 4C) to control the degree of superheat so that the discharge pipe temperature of the compressor (1) becomes substantially constant. Determination means (32)
Is the measured discharge pipe temperature (DO) is the target discharge pipe temperature
(SET2) based on the above reference value (AG2 × SETDO)
+ BG2) and when the degree of opening of the motor-operated valves (4A, 4B, 4C) is equal to or greater than a predetermined degree of opening, it is determined that there is no gas. 4. The refrigerating apparatus according to claim 1, wherein the timer means measures a predetermined time.
(34), wherein the gas shortage determination means (32) determines that there is a gas shortage when the gas shortage state continues for a predetermined time or more by the timer means (34). Refrigeration equipment.