JPH0712409A - Refrigerating device - Google Patents

Abstract

PURPOSE:To provide a refrigerating device, capable of preventing the overheat of discharging temperature of a compressor smoothly by a liquid injection circuit from the starting of the compressor without increasing the number of parts and/or complicating the structure of the device. CONSTITUTION:A compressor A, a condenser B, a liquid receiver C, an expansion valve D and an evaporator E are connected sequentially so as to be annularly. A liquid injection circuit K3, supplying liquid refrigerant from the liquid receiver C into the compressor A, is provided. A solenoid valve SV1 and a flow rate control valve V are interposed in the liquid injection circuit K3. The opening degree of the flow rate control valve V is regulated on the basis of the temperature of discharging gas of the compressor A. The flow rate control valve V secures the predetermined flow rate of refrigerant even at the closed position thereof.

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 preventing the discharge temperature of a compressor from overheating.

[0002]

2. Description of the Related Art Conventionally, in this type of refrigerating and air-conditioning equipment, when the temperature of discharge gas of a compressor constituting a refrigerating cycle of a refrigerating apparatus rises abnormally, seizure of a sliding portion of the compressor and burnout of windings occur. Therefore, the cooling method by liquid injection is adopted. This cooling system lowers the discharge gas temperature of the compressor by supplying the liquid refrigerant in the liquid receiver to the intermediate pressure part of the compressor by a liquid injection circuit. Further, conventionally, the supply of the liquid refrigerant by the liquid injection circuit was generally controlled by interposing a capillary tube and an opening / closing valve, but for the purpose of optimizing the liquid refrigerant supply amount, the liquid injection circuit is not provided. In place of the capillary tube, a flow rate control valve composed of an expansion valve has been installed.

Liquid injection by such an expansion valve system is carried out by detecting the temperature of the discharge pipe of the compressor by the temperature sensing cylinder of the flow control valve and adjusting the valve opening thereof. As the temperature rises, the valve opening is expanded as shown by the alternate long and short dash line in FIG. 4 to increase the refrigerant flow rate, thereby supplying and cooling an appropriate amount of liquid refrigerant to the compressor.

[0004]

However, as is apparent from FIG. 4, the conventional flow rate control valve completely sets the valve opening degree to 0 in the valve closed position, and thereby sets the refrigerant flow rate to 0 as well. On the other hand, the temperature-sensitive cylinder has a heat capacity, and there is a delay in its temperature detection.Therefore, if the discharge gas temperature rises sharply at the start of the compressor, the valve opening operation of the flow control valve is inevitable. However, there is a problem that the supply of the liquid refrigerant is insufficient and the allowable limit of the discharge gas temperature is greatly exceeded as shown by the alternate long and short dash line in FIG.

For this reason, conventionally, a capillary tube or the like that bypasses the flow rate control valve is added to compensate for the valve opening delay with respect to such a rapid temperature rise, but the number of parts increases and the cost increases. is there. Also,
There is also a compressor in which a hole for inserting a temperature-sensitive cylinder is formed so that a rise in discharge gas temperature can be sensed quickly, but in that case, there is a problem that the structure becomes complicated.

The present invention has been made in order to solve the above-mentioned conventional technical problems, and a liquid injection circuit is provided from the time of starting the compressor without increasing the number of parts and complicating the structure. Therefore, it is an object of the present invention to provide a refrigeration system capable of smoothly preventing the discharge gas temperature of a compressor from overheating.

[0007]

That is, in a refrigerating apparatus 20 of the present invention, a compressor A, a condenser B, a liquid receiver C, a pressure reducing device (expansion valve) D and an evaporator E are sequentially connected in an annular shape. A liquid injection circuit K3 for supplying a liquid refrigerant from the liquid receiver C to the compressor A is provided, and an on-off valve (expansion valve) SV1 and a flow control valve V are interposed in the liquid injection circuit K3. Therefore, the flow rate control valve V adjusts the valve opening degree based on the discharge gas temperature of the compressor A, and also secures a predetermined refrigerant flow rate even in the valve closed position.

[0008]

According to the refrigerating apparatus 20 of the present invention, since the flow control valve V provided in the liquid injection circuit K3 secures a predetermined refrigerant flow rate even in the valve closed position, the compressor A is started. When the discharge gas temperature rises rapidly at times, at least the predetermined amount of the liquid refrigerant can be supplied to the compressor A even if the valve opening operation of the flow control valve V is delayed. Therefore, the discharge gas temperature is prevented from overheating due to the valve opening delay of the flow rate control valve V.

In particular, since it is not necessary to additionally use a bypass pipe and a capillary tube as in the conventional case, the number of parts can be reduced and the structure can be simplified. Since the on-off valve (solenoid valve) SV1 is closed when the compressor A is stopped, there is no problem even if the flow control valve V secures the predetermined flow rate at the valve closed position as described above. Does not occur.

[0010]

An embodiment of the present invention will be described in detail with reference to the drawings. 1 is a refrigerant circuit diagram of a refrigerating apparatus 20 of the present invention, FIG.
5 is a vertical side view of the flow control valve V, FIG. 3 is an enlarged vertical side view of the valve body 2 of the flow control valve V, FIG. 4 is a view showing the relationship between the valve opening of the flow control valve V and the refrigerant flow rate, FIG. 6 is a diagram showing a time transition of the discharge gas temperature of the compressor A, and FIG. 6 is a vertical cross-sectional side view of the scroll 22 of the switch compression unit 21 in the compressor A. In FIG. 1, A is, for example, a scroll type compressor, B is a condenser, C is a liquid receiver, D is an expansion valve as a pressure reducing device, E is an evaporator, F is an accumulator, and these are sequentially provided by a pipe K. The refrigeration cycle of the refrigeration system 20 is configured by being connected in a ring shape. G is a temperature sensitive tube of the expansion valve D, which is attached to the outlet side pipe (suction side pipe) K2 of the evaporator E and is connected to the expansion valve D by a capillary tube H.

From the pipe K between the outlet side of the liquid receiver C and the expansion valve D, the scroll compression section 2 of the compressor A shown in FIG.
Intermediate pressure (AP2) portion 23A of the compression space 23 in No. 1
Is provided with a liquid injection circuit K3, which is provided with a solenoid valve SV1 serving as an opening / closing valve and a flow control valve V including an expansion valve.

2 and 3 show the detailed structure of the flow rate control valve V. The valve body 1 has a primary port 1a and a secondary port 1b.
The valve body 2 for opening and closing the valve opening 1d formed in the partition wall 1c between the primary opening 1a and the secondary opening 1b is provided by being biased in the valve closing direction by the coil spring 3 on the secondary opening 1b side. ing. Incidentally, 4 is a receiver of the coil spring 3.

A lower lid 5 and an upper lid 6 are provided on the primary port 1a side of the valve body 1, and a peripheral edge portion 7 is provided between the lower lid 5 and the upper lid 6.
By fixing a and 8a by argon welding,
Two stacked metal diaphragms 7 and 8 are provided to partition the pressure chamber R1 and the pressure chamber R2. The interlocking rod 10 is attached to the spring receiver 9 that abuts on the inner diaphragm 7.
One end of the interlocking rod 10 is connected to the small diameter portion 1 at the other end of the interlocking rod 10.
0a penetrates the valve opening 1d and is in contact with the valve body 2.
A pressure setting coil spring 11 is provided between the spring receiver 9 and the main body 1.

Further, the small diameter portion 10a of the interlocking rod 10 of the flow control valve V is pushed down the small valve body 2 as shown in FIG. 3 while the compressor A is stopped and in the valve closed position to open the valve opening. 1d
Is opened, and a predetermined flow rate is secured at the valve closed position (0) as shown by the solid line in FIG. The flow rate increases as the valve opening increases. The capillary tube 12 is provided in the pressure chamber R2 of the flow control valve V.
The temperature sensitive cylinder 13 is connected via the
Is attached to the discharge side pipe K1. A predetermined amount of refrigerant is enclosed in the temperature sensitive cylinder 13.

On the other hand, the compressor A is provided with a capacity control device 26 of an in-cylinder bypass system. The capacity control device 26 includes a high-pressure pipe K4 that communicates with the discharge-side pipe K1 of the compressor A, a low-pressure pipe K5 that communicates with the suction-side pipe K2 on the inlet side of the accumulator F, and a check valve provided in the high-pressure pipe K4. Valve 27 and solenoid valve SV2, low pressure pipe K
5, a check valve 28 and a solenoid valve SV3, and a communication pipe K6 connected to the scroll 22 of the compressor A,
It is composed of bypass valves 29, 29 provided in the scroll 22.

The check valve 27 is provided on the discharge side pipe K1 side of the solenoid valve SV2, the solenoid valve SV2 direction is the forward direction, and the check valve 28 is provided on the suction side pipe K2 side of the solenoid valve SV3. The direction of the pipe K2 is the forward direction. Further, one end of the communication pipe K6 communicates with the high pressure pipe K4 and the low pressure pipe K5 between the solenoid valves SV2 and SV3, and the other end communicates with the upper surfaces of the bypass valves 29, 29 of the scroll 22 as shown in FIG. ing. Further, the intermediate pressure portion 23A and the suction portion 23B of the compression space 23 communicate with the lower surface of the bypass valve 29. Further, the solenoid valves SV2, SV3 are controlled to be opened and closed by the capacity control switch 31, and the compressor A
The solenoid valve SV1 is operated / stopped or controlled to be opened / closed by a high / low pressure switch 32 which operates by sensing the high pressure / low pressure of the compressor A.

The operation will be described with the above configuration. When the compressor A is started by the high / low pressure switch 32, the compression unit 21
The high-temperature and high-pressure gas refrigerant discharged from is condensed and liquefied in the condenser B, then temporarily stored in the liquid receiver C, then decompressed by the expansion valve D, and then evaporated in the evaporator E. The refrigerating apparatus 20 exerts a cooling capacity by the endothermic action generated at this time. In this way, since the high temperature gas refrigerant is discharged from the compressor A, the temperature of the discharge side pipe K1 rapidly rises.

Simultaneously with the start of the compressor A, the high / low pressure switch 32 also opens the solenoid valve SV1. Then, when the temperature of the discharge side pipe K1 rises, the refrigerant pressure in the temperature sensing cylinder 13 rises and the pressure VP2 of the pressure chamber R2 in the flow control valve V.
Rise, the pressure VP1 in the pressure chamber R1 and the springs 11 and 3 are increased.
Overcoming the elastic force of the diaphragms 7 and 8 and the interlocking rod 10
Is moved downward, the valve body 2 is separated from the valve opening 1d, and the valve opening becomes large as shown by the solid line in FIG. As a result, a part of the liquid refrigerant in the receiver C is supplied from the liquid injection circuit K3 to the intermediate pressure portion 23A of the compressor A, and the discharge gas temperature of the compressor A is lowered.

Here, if the discharge gas temperature changes abruptly at the time of starting the compressor A, the temperature detection is delayed due to the heat capacity of the temperature sensing cylinder 13. Therefore, immediately after the compressor A is started, the valve body 2 does not operate and is in the valve closed position, but as described above, the valve body 2 of the flow control valve V is slightly separated from the valve opening 1d at the valve closed position, For example, the maximum flow rate of 10% to 20% is secured as the leakage flow rate. Therefore, the compressor A starts and the solenoid valve S
When V1 is opened, the supply of the liquid refrigerant is started at that time, so that the rise of the discharge gas temperature at the time of starting the compressor A is suppressed as shown by the solid line in FIG.

As a result, the discharge gas temperature is prevented from overheating (a temperature exceeding the allowable limit), and the occurrence of damage to the compressor A is eliminated, so that the reliability can be improved.
Further, since the solenoid valve SV1 is closed at the same time as the compressor A is stopped by the high / low pressure switch 32, even if the flow rate control valve V secures a predetermined flow rate at the valve closed position as described above, the compressor A is stopped. Since the supply of the liquid refrigerant from the liquid injection circuit K3 is stopped at times, no problem occurs.

Here, in the above-mentioned flow rate control valve V, the compressor A is secured by ensuring a predetermined flow rate at the valve closed position.
Although the overheating of the discharge gas temperature at the time of starting the above is eliminated, in addition to or in addition to it, as a refrigerant to be sealed in the temperature sensing cylinder 13 of the flow control valve V, a mixture of two or more different refrigerants should be sealed. Also, the overheating of the discharge gas temperature can be effectively eliminated. Hereinafter, as the flow rate control valve V of FIG. 1, a normal flow rate control valve (having a flow rate of 0 at the valve closed position) is used, and a mixed refrigerant of the refrigerant R-142b and the refrigerant R-22 is enclosed in the temperature sensing cylinder 13. The case will be described.

In this case, R-142b and R-2
If the saturated vapor pressure is 2, the first characteristic L1 (R142b is 68.9 wt%, as shown in FIG. 9)
R-22 is 31.1 wt%, second characteristic L2 (R14
2b is 75.6 wt% and R-22 is 24.4 wt%),
Third characteristic L3 (R142b is 80.1 wt%, R-2
2 is 19.9 wt%), and each saturation curve of the fourth characteristic L4 (R142b is 82.1 wt%, R-22 is 17.9 wt%) is obtained, thereby obtaining a superheat degree of an arbitrary characteristic. You can Therefore, the scroll type compressor A
By setting the mixture ratio of the enclosed refrigerant to the appropriate set superheat degree of + 30 ° C. to 40 ° C., the discharge gas temperature greatly exceeds the allowable limit at the time of starting the compressor A as shown in FIG. Thus, it becomes possible to keep it within the allowable limit. The properly set superheat degree is around + 45 ° C in the case of a reciprocating compressor, and is + 20 ° C to 30 ° C in the case of a rotary compressor.

Next, the operation of the capacity control device 26 will be described with reference to FIG. The capacity control device 26
It is provided for the purpose of prolonging the life of the compressor A by avoiding the operation / stop of the compressor A as much as possible with respect to the change of the load of the refrigeration system 20, and the low pressure (AP
Although 3) is decreasing, for example, when it is higher than 1 kg / cm ² G, the capacity control switch 31 opens the solenoid valve SV2 and closes the solenoid valve SV3. Therefore, the bypass valve 2
Since the high pressure (AP1) of the discharge side pipe K1 is applied to the upper surfaces of 9 and 29, the bypass valves 29 and 29 are closed, and therefore the compressor A operates at 100%.

After that, the low pressure was further reduced to 1 kg / cm.
Below ² G, the capacity control switch 31 causes the solenoid valve SV2
Is closed and the solenoid valve SV3 is opened, so that the high pressure (AP1) escapes to the suction side pipe K2, and the bypass valves 29, 29 are pushed up by the intermediate pressure (AP2) of the intermediate pressure portion 23A and opened,
The intermediate compressed gas of the intermediate pressure portion 23A is returned to the suction portion 23B. As a result, the refrigerant circulation amount decreases, so that the compressor A operates at 60%. After that, the low pressure rises to 2
When the pressure exceeds kg / cm ² G, the capacity control switch 31 opens the solenoid valve SV2 again and closes SV3, so that the bypass valves 29, 29 are closed and the compressor A operates at 100%.

Further, when the load is small and the low pressure is reduced to, for example, 0.6 kg / cm ² G or less even by the above 60% operation, the high / low pressure switch 32 stops the compressor A (simultaneously with the solenoid valves SV1 to SV3). Also close). Then, when the low pressure rises again and becomes, for example, 1.7 kg / cm ² G or more, the high / low pressure switch 32 starts the compressor A and opens the solenoid valve SV1, and the capacity control switch 31 causes the solenoid valve SV to open.
Compressor A is 100% because V2 is opened and SV3 is closed.
It will be started by driving.

Here, as the compressor A is stopped, the high pressure AP1
Becomes lower than the intermediate pressure AP2, the solenoid valve SV
There is a risk of causing so-called chattering and making an abnormal sound because the back pressure is about to be applied to 2. However, since the check valve 27 is provided in the present embodiment, the back pressure is prevented, and therefore the abnormal sound is generated. The problems that occur are eliminated. Further, when the compressor A fails and is replaced, one of the solenoid valves SV3 (the one on the compressor A side) becomes the body pressure and the other suction side pipe K2 side becomes the low pressure AP3. Although there is a risk that gas leakage will occur due to the application of back pressure, in the embodiment, since the check valve 28 is provided, such gas leakage is effectively prevented.

[0027]

As described in detail above, according to the present invention, the flow control valve provided in the liquid injection circuit is
Since a predetermined refrigerant flow rate is secured even in the valve closed position, if the discharge gas temperature rises sharply when the compressor is started, etc., even if there is a delay in the valve opening operation of the flow control valve,
At least the predetermined amount of liquid refrigerant can be supplied to the compressor. Therefore, it is possible to prevent the discharge temperature from being overheated due to the valve opening delay of the flow rate control valve, and effectively avoid the damage of the compressor. In particular, since it is not necessary to additionally use a bypass pipe and a capillary tube as in the conventional case, the number of parts can be reduced and the structure can be simplified.

[Brief description of drawings]

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

FIG. 2 is a vertical sectional side view of a flow control valve.

FIG. 3 is an enlarged vertical side view of a valve body portion of the flow control valve.

FIG. 4 is a diagram showing a relationship between a valve opening degree of a flow rate control valve and a refrigerant flow rate.

FIG. 5 is a diagram showing a time transition of a discharge gas temperature of a compressor.

FIG. 6 is a vertical sectional side view of a scroll in the compressor.

FIG. 7 is a diagram showing a time transition of a low pressure of the compressor for explaining the operation of the capacity control device.

FIG. 8 is a diagram showing a time transition of temperature and pressure of each part of the refrigeration apparatus when the two-type mixed refrigerant is enclosed in the temperature sensitive cylinder of the flow control valve.

FIG. 9 is a diagram showing the characteristics of the refrigerant sealed in the temperature sensitive cylinder of the flow control valve.

FIG. 10 is a diagram showing a time transition of temperature and pressure of each part of the refrigeration system when a conventional flow control valve is used.

[Explanation of symbols]

 A compressor B condenser C liquid receiver D expansion valve E evaporator K3 liquid injection circuit SV1 solenoid valve V flow control valve

Claims (1)

[Claims] 1. A compressor, a condenser, a liquid receiver, a decompression device and an evaporator are sequentially connected in an annular shape, and a liquid injection circuit for supplying a liquid refrigerant from the liquid receiver to the compressor is provided. In the refrigeration system in which the on-off valve and the flow control valve are provided in the injection circuit,
The refrigerating apparatus, wherein the flow rate control valve adjusts a valve opening degree based on a discharge gas temperature of the compressor and ensures a predetermined refrigerant flow rate even in a valve closed position.