JP3091594B2 - 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 refrigerating apparatus having a liquid injection circuit for cooling a compressor and performing defrosting of an evaporator by using a high-temperature refrigerant.

[0002]

2. Description of the Related Art In recent years, in this type of refrigeration system, the use of a so-called specific refrigerant such as Freon R-12 has been restricted due to the problem of destruction of the ozone layer by Freon, and Freon R-22 has been used instead. It is coming. However, such a refrigerant has a low evaporation temperature (−40 ° C.) and
It has the property that the temperature of the discharge gas of the compressor rises. Therefore, if such a refrigerant is used as it is, the temperature of the discharge gas of the compressor exceeds a high temperature such as + 150 ° C., and the temperature of the compressor winding becomes higher than the limit temperature. Therefore, in order to prevent the temperature of the compressor from rising, this type of refrigeration system is disclosed, for example, in Japanese Patent Application No. 4-56 filed by the applicant.
A liquid injection circuit as in No. 12 is provided.

That is, in the above-mentioned application, a liquid injection circuit is provided from an outlet of a liquid receiver (receiver) for storing liquid refrigerant from a condenser to a compressor, and compresses the liquid refrigerant stored in the liquid receiver. The compressor is cooled by returning it to the evaporator to reduce its temperature.

[0004]

However, in a refrigeration system as described above, a high-temperature refrigerant discharged from a compressor flows directly into an evaporator, not a condenser, to defrost the evaporator. Is performed, the refrigerant is not stored in the liquid receiver, so that the liquid refrigerant flowing to the liquid injection circuit is depleted.

[0005] When the liquid refrigerant stops flowing in the liquid injection circuit due to the depletion of the refrigerant in the liquid receiver, the cooling of the compressor is not performed, and the discharge gas temperature of the compressor rises. Therefore, as described above, the protection device (discharge gas thermostat or the like) normally provided in the compressor to prevent the failure works, and the compressor stops. When the compressor is stopped, the evaporator is naturally not defrosted, and the refrigeration capacity is significantly reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional technical problem. In the case where a compressor is cooled by a liquid injection circuit, the compressor can be used even when so-called hot gas defrosting is performed. It is an object of the present invention to provide a refrigeration apparatus capable of securing a liquid refrigerant for cooling.

[0007]

According to a first aspect of the present invention, there is provided a refrigerating apparatus in which a compressor 1, a condenser 3, a liquid receiver 4, a pressure reducing device (expansion valve) 8, and an evaporator 9 are sequentially connected in a ring shape. And a liquid injection circuit 16 for supplying liquid refrigerant from the liquid receiver 4 to the compressor 1, wherein the high-temperature refrigerant discharged from the compressor 1 flows into the evaporator 9.
4 and a bypass circuit 21 for guiding a liquid refrigerant to be supplied to the compressor 1 from the outlet side of the evaporator 9 to the inlet side of the receiver 4. It is characterized in that a valve (check valve) 22 for blocking refrigerant flow toward the outlet side is provided.

In the refrigeration apparatus according to the second aspect of the present invention, the compressor 1, the condenser 3, the liquid receiver 4, the pressure reducing device (expansion valve) 8, and the evaporator 9 are sequentially connected in a ring shape. 4, a liquid injection circuit 16 for supplying a liquid refrigerant from the compressor 1 to the compressor 1. The defrosting circuit 14 connects the discharge side of the compressor 1 and the inlet side of the evaporator 9, and the condenser 3 A control device 23 for controlling the flow of the refrigerant to the frost circuit 14 is provided. The control device 23 prevents the flow of the refrigerant to the condenser 3 from the start of the defrosting of the evaporator 9 and allows the refrigerant to flow to the defrosting circuit 14. When a predetermined period has elapsed from the start of defrosting, the refrigerant is circulated through both the defrosting circuit 14 and the condenser 3.

[0009]

According to the refrigeration apparatus of the first aspect, the evaporator 9 is provided.
At the time of the defrosting, the high-temperature refrigerant discharged from the compressor 1 by the defrosting circuit 14 flows into the evaporator 9 to defrost the evaporator 9. The high-temperature refrigerant flowing into the evaporator 9 is condensed, separated into gas and liquid, and returned to the compressor 1. During the defrosting, the pressure in the liquid receiver 4 becomes lower than the pressure on the outlet side of the evaporator 9, whereby a part of the refrigerant condensed and liquefied in the evaporator 9 passes through the bypass circuit 21 and passes through the valve (check valve). Through the valve 22). The liquid refrigerant collected in the liquid receiver 4 is supplied to the compressor 1 by the liquid injection circuit 16, and the compressor 1 is cooled.

According to the refrigeration apparatus of the second aspect, when the evaporator 9 is defrosted, the control device 23 controls the condenser 3.
The high-temperature refrigerant discharged from the compressor 1 is instead flown into the evaporator 9 by the defrost circuit 14 to defrost the evaporator 9. The high-temperature refrigerant flowing into the evaporator 9 is condensed, separated into gas and liquid, and returned to the compressor 1.
When a predetermined period has elapsed from the start of the defrosting, the control device 2
3 flows the refrigerant to both the defrost circuit 14 and the condenser 3,
The liquid refrigerant is stored in the liquid receiver 4 while the evaporator 9 is being defrosted. The liquid refrigerant stored in the liquid receiver 4 is supplied to the compressor 1 by a liquid injection circuit 16,
The compressor 1 is cooled.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a refrigerant circuit diagram of the refrigeration apparatus of the present invention. The refrigerating apparatus is used for cooling, for example, a super showcase or a commercial prefabricated refrigerator, and a piping 2 on a discharge side of a compressor 1 including a rotary compressor, a scroll compressor, and the like is provided with an electromagnetic valve S.
The condenser 3 is connected to the condenser 3 via V 2, and the outlet side of the condenser 3 is connected to the liquid receiver 4. Outlet side pipe 6 of liquid receiver 4
Is connected via a liquid pipe solenoid valve 7 to an expansion valve 8 as a pressure reducing device, and the expansion valve 8 is connected to an evaporator 9. The outlet side of the evaporator 9 is connected to an accumulator 12 via a suction pressure regulating valve 11, and the accumulator 12 is connected to a pipe 13 on the suction side of the compressor 1 to form an annular refrigerant circuit.

An electromagnetic valve SV3 is connected in parallel with the expansion valve 8, and a defrosting circuit 14 is connected to the pipe 2 on the upstream side of the electromagnetic valve SV2.
1 is connected between the expansion valve 8 and the evaporator 9.
A liquid injection circuit 16 is connected to the pipe 6 between the liquid receiver 4 and the liquid tube electromagnetic valve 7, and the liquid injection circuit 16 is connected to the compressor 1 via an electromagnetic valve 17 and a capillary tube 18.

Further, a bypass circuit 21 is connected between the evaporator 9 and the suction pressure regulating valve 11, and the bypass circuit 21
Is connected to the inlet side of the liquid receiver 4 via a check valve 22. In the check valve 22, the direction of the liquid receiver 4 is set to the forward direction.

Reference numeral 19 denotes a control device constituted by a microcomputer, for example, which includes a timer, a sensor for detecting the temperature of the interior of the showcase and the temperature of the evaporator 9, and the like. The compressor 1 and the solenoid valve SV1 , SV2 and SV3. In the following description, it is assumed that the liquid pipe solenoid valve 7 and the solenoid valve 17 are open, but the solenoid valve 17 is opened by the control device 19 based on the temperature of the compressor 1 when the temperature rises and falls. Then, close control may be performed. The control device 19 detects the temperature of the compressor 1 and has a protection function of stopping the compressor 1 when the temperature rises to a high temperature such as + 150 ° C., for example.

Next, the operation of the refrigeration apparatus shown in FIG. 1 will be described.
It is assumed that a predetermined amount of the R-22 refrigerant is sealed in the refrigerant circuit of FIG. The control device 19 controls the operation of the compressor 1 based on the inside temperature of the showcase, and closes the solenoid valves SV1 and SV3 and opens the solenoid valve SV2 during the cooling operation. As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 3 via the solenoid valve SV2, and the refrigerant radiates heat there to be condensed and liquefied, and then flows into the liquid receiver 4. The liquid refrigerant once stored in the liquid receiver 4 reaches the expansion valve 8 via the pipe 6, is throttled there, and flows into the evaporator 9.

The refrigerant flowing into the evaporator 9 evaporates there,
At that time, a cooling effect is exhibited by absorbing heat from the surroundings. The refrigerant leaving the evaporator 9 enters the accumulator 12 via the suction pressure regulating valve 11, where the unevaporated liquid refrigerant is gas-liquid separated, and then only the gas refrigerant is sucked into the compressor 1. During the cooling operation, the inlet side of the liquid receiver 4 has a higher pressure than the outlet side of the evaporator 9, so that the check valve 22 prevents the refrigerant from flowing from the evaporator 9 to the bypass circuit 21. .

On the other hand, a part of the liquid refrigerant flowing out of the liquid receiver 4 also flows into the liquid injection circuit 16 and the electromagnetic valve 1
After being squeezed by the capillary tube 18 through 7, it is discharged into the compressor 1. The liquid refrigerant evaporates in the compressor 1 and exerts an endothermic effect to cool the compressor 1. This prevents the temperature of the compressor 1 from rising during the cooling operation, so that the compressor 1 is not stopped by the protection function of the control device 19.

Here, the control device 19 accumulates, for example, the operation time of the compressor 1 by the timer, and when a predetermined time is reached, the defrosting operation of the evaporator 9 is started. In this defrosting operation, the control device 19 operates the compressor 1 and initially opens the solenoid valve SV to introduce the liquid refrigerant directly into the evaporator 9, and defrosts the evaporator 9 by the sensible heat of the liquid refrigerant. To start.
After performing such defrosting, for example, for 30 seconds, the control device 19 closes the solenoid valve SV2 and opens the solenoid valve SV1 to flow the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 to the defrost circuit 14 and to the evaporator 9 Let it flow in.

The evaporator 9 is heated by the flow of the high-temperature and high-pressure gas refrigerant, and its frost is melted. The refrigerant that has flowed into the evaporator 9 is condensed and liquefied there, exits the evaporator 9, is depressurized and adjusted by the suction pressure control valve 11, enters the accumulator 12, where it is gas-liquid separated and only the gas refrigerant is compressed. It is sucked into the machine 1.

On the other hand, during the defrosting operation, the outlet side of the evaporator 9 has a higher pressure than the inlet side of the liquid receiver 4. Therefore, a part of the liquid refrigerant that has flowed out of the evaporator 9 due to the pressure difference flows into the bypass circuit 21 and is collected by the liquid receiver 4 through the check valve 22. The refrigerant is not depleted. The liquid refrigerant collected in the receiver 4 exits from the pipe 6 and flows into the liquid injection circuit 16, and is throttled by the capillary tube 18 via the solenoid valve 17 in the same manner as described above. It is discharged into.

As described above, since the liquid refrigerant is supplied to the liquid injection circuit 16 even during the defrosting operation, the temperature rise of the compressor 1 during the defrosting operation is also reliably prevented,
The compressor 1 is not stopped by the protection function of the control device 19. Therefore, the defrosting of the evaporator 9 is reliably performed, and the occurrence of cooling failure due to the remaining frost is also prevented. The controller 19 ends the defrosting operation when the temperature of the evaporator 9 rises to a predetermined defrosting end temperature, and returns to the cooling operation.

Next, FIG. 2 shows a refrigerant circuit diagram of another refrigeration apparatus. In the figure, components having the same reference numerals as those in FIG. 1 perform the same functions. In this case, the solenoid valve SV3, the bypass circuit 21, and the check valve 22 in FIG. 1 are omitted. Then, the control device 23 is the control device 19 of FIG.
And its defrost control program are different.

Hereinafter, the operation of the refrigeration apparatus of FIG. 2 will be described.
It is assumed that a predetermined amount of the R-22 refrigerant is also sealed in the refrigerant circuit of FIG. The control device 23 controls the operation of the compressor 1 based on the inside temperature of the showcase, and closes the solenoid valve SV1 and opens the solenoid valve SV2 during the cooling operation. Thereby, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 3 via the solenoid valve SV2,
Then, the heat is released and condensed and liquefied, and then flows into the receiver 4. The liquid refrigerant once stored in the liquid receiver 4 reaches the expansion valve 8 via the pipe 6, is throttled there, and flows into the evaporator 9.

The refrigerant flowing into the evaporator 9 evaporates there,
At that time, a cooling effect is exhibited by absorbing heat from the surroundings. The refrigerant leaving the evaporator 9 enters the accumulator 12 via the suction pressure regulating valve 11, where the unevaporated liquid refrigerant is separated into gas and liquid, and then sucked into the compressor 1.

On the other hand, a part of the liquid refrigerant flowing out of the liquid receiver 4 also flows into the liquid injection circuit 16 and the electromagnetic valve 1
After being squeezed by the capillary tube 18 through 7, it is discharged into the compressor 1. The liquid refrigerant evaporates in the compressor 1 and exerts an endothermic effect to cool the compressor 1. This prevents the temperature of the compressor 1 from rising during the cooling operation, so that the compressor 1 is not stopped by the protection function of the control device 23 similar to the above.

Here, the controller 23 accumulates the operation time of the compressor 1 by the same timer as described above, and starts the defrosting operation of the evaporator 9 at a predetermined time. In this defrosting operation, the control device 23 operates the compressor 1 and
The solenoid valve SV2 is closed, the solenoid valve SV1 is opened, and the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows to the defrost circuit 14,
It flows into the evaporator 9.

The evaporator 9 is heated by the flow of the high-temperature and high-pressure gas refrigerant, and its frost is melted. The refrigerant that has flowed into the evaporator 9 is condensed and liquefied there, exits the evaporator 9, is depressurized and adjusted by the suction pressure control valve 11, enters the accumulator 12, where it is gas-liquid separated and only the gas refrigerant is compressed. It is sucked into the machine 1.

The controller 23 opens the solenoid valve SV2 after a lapse of a predetermined period from the start of the defrosting operation. Thus, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 3 in addition to the defrost circuit 14. The refrigerant flowing into the condenser 3 is condensed and liquefied and stored in the receiver 4, so that the liquid refrigerant in the receiver 4 is not depleted. The liquid refrigerant stored in the liquid receiver 4 exits from the pipe 6 and is supplied to the liquid injection circuit 1.
6, is throttled by a capillary tube 18 via an electromagnetic valve 17 in the same manner as described above, and then discharged into the compressor 1.

As described above, the liquid refrigerant to the liquid injection circuit 16 is ensured even during the defrosting operation, so that the temperature rise of the compressor 1 during the defrosting operation is reliably prevented.
The compressor 1 is no longer stopped by the protection function of the control device 23, and therefore, the defrosting of the evaporator 9 is reliably performed. The controller 23 ends the defrosting operation when the temperature of the evaporator 9 rises to a predetermined defrosting end temperature, and returns to the cooling operation.

In the embodiment, the check valve 22 is provided in the bypass circuit 21. However, the present invention is not limited to this. An electromagnetic valve may be provided and the electromagnetic valve may be closed during the cooling operation and opened during the defrosting operation. In the embodiment, the control device is configured by a microcomputer, and the microcomputer is provided with a compressor protection function.However, the compressor is protected by using a discharge gas thermo or the like that detects the temperature of the compressor. No problem. Furthermore, the refrigerator of the present invention is not limited to a showcase,
Needless to say, it is effective for various other refrigeration equipment.

[0031]

As described above, according to the first aspect of the present invention, even during the defrosting of the evaporator by the high-temperature refrigerant, the refrigerant condensed and liquefied by the evaporator passes through the bypass circuit and is collected in the receiver. Therefore, the depletion of the liquid refrigerant in the liquid receiver is prevented. Therefore, the liquid refrigerant to the liquid injection circuit is secured, so that the compressor can be cooled even during the defrosting of the evaporator, and the failure of the compressor occurs and the cooling failure occurs due to the remaining frost. Can be prevented beforehand.

According to the second aspect of the present invention, when a predetermined period has elapsed from the start of the defrosting of the evaporator by the high-temperature refrigerant, the control device flows the refrigerant to both the defrosting circuit and the condenser. The liquid refrigerant is stored in the liquid receiver while the container is being defrosted, thereby preventing the liquid refrigerant in the liquid receiver from being depleted. Therefore,
Since the liquid refrigerant to the liquid injection circuit is secured, it is possible to cool the compressor even during defrosting of the evaporator. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus of the present invention.

FIG. 2 is a refrigerant circuit diagram of another refrigeration apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 3 Condenser 4 Liquid receiver 8 Expansion valve 9 Evaporator 14 Defrost circuit 16 Liquid injection circuit 19 Control device 21 Bypass circuit 22 Check valve 23 Control device SV1 Solenoid valve SV2 Solenoid valve SV3 Solenoid valve

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-126554 (JP, A) JP-A-56-37460 (JP, A) JP-A-1-159564 (JP, A) JP-A-3-3 220355 (JP, A) Japanese Utility Model Showa 58-174660 (JP, U) Japanese Utility Model Showa 54-153050 (JP, U) Japanese Utility Model 2-81367 (JP, U) Japanese Utility Model Utility Model 2-6970 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 47/02 530 F25B 1/00 311

Claims (2)

(57) [Claims] 1. A refrigerating apparatus in which a compressor, a condenser, a liquid receiver, a pressure reducing device, and an evaporator are sequentially connected in a ring shape and a liquid injection circuit for supplying a liquid refrigerant from the liquid receiver to the compressor is provided. And a defrost circuit for flowing high-temperature refrigerant discharged from the compressor into the evaporator, and guiding a liquid refrigerant to be supplied to the compressor from an outlet side of the evaporator to an inlet side of the liquid receiver. A refrigerating apparatus comprising: a bypass circuit; and a valve for preventing refrigerant from flowing toward an outlet of the evaporator. 2. A refrigerating apparatus in which a compressor, a condenser, a liquid receiver, a pressure reducing device, and an evaporator are sequentially connected in a ring shape, and a liquid injection circuit for supplying a liquid refrigerant from the liquid receiver to the compressor is provided. A defrost circuit that communicates between the discharge side of the compressor and the inlet side of the evaporator, and a control device that controls refrigerant flow to the condenser and the defrost circuit, wherein the control device is configured to control the evaporator. While preventing the circulation of the refrigerant to the condenser from the start of defrost and allowing the refrigerant to flow through the defrost circuit, when a predetermined period has elapsed from the start of the defrost, the refrigerant is supplied to both the defrost circuit and the condenser. A refrigeration system characterized by being distributed.