JP2001174077A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a new refrigerant without chlorine causing damage to the ozone layer, and to achieve a safe refrigeration cycle in various operation pressures and temperatures. SOLUTION: In a refrigeration device that is equipped with a scroll compressor 1, a condenser 2, and a receiver 3, and is connected to an evaporator 6 via an expansion valve 5, the downstream side of the condenser 2 is connected to the scroll compressor 1 by liquid injection piping 12. The liquid injection piping 12 has an injection valve 36 where the amount of liquid injection is controlled related to the discharge-side temperature of the compressor 1, or an electronic expansion valve 10. The condenser 2 uses a heat exchanger with a smaller diameter than that of the heat exchanger for composing the evaporator 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus used for an air conditioner, a refrigerating machine, etc., and is particularly suitable for a refrigerating apparatus using a mixed refrigerant containing no chlorine.

[0002]

2. Description of the Related Art Conventionally, as a working fluid of a refrigeration cycle, a fluorinated hydrocarbon-based refrigerant containing chlorine, such as so-called CFC or HCFC, is an optimum material as a refrigerant due to its excellent thermodynamic properties and stability. It was used as the mainstream.

[0003] As a refrigerating apparatus using these refrigerants, for example, Japanese Patent Application Laid-Open Nos.
As described in JP-A-84049 and JP-A-5-172408, overheating of the compressor is prevented and a wide operating pressure range is achieved.

[0004]

The fluorocarbon-based material containing chlorine reaches the stratosphere by convection without decomposing due to its stability. And it has been revealed that it has a function of destroying the ozone layer because it is decomposed by strong ultraviolet light in the sky to release chlorine atoms that react with ozone. In order to protect the ozone layer which functions to block ultraviolet rays harmful to the human body in the sky, the elimination of fluorocarbon-based substances containing chlorine has been determined. HCFC22, which is widely used as a refrigerant in air conditioners and refrigerators, is also a subject. Since the effect on the ozone layer destruction is smaller than that of CFCs, which are so-called specific CFCs, the grace period until the total abolition is set longer. I have. During this grace period, it is essential to develop a substitute refrigerant and a refrigeration system compatible with the substitute refrigerant.

[0005] New refrigerants which are currently being considered as alternatives to conventional refrigerants such as HCFC22 include, for example, fluorinated hydrocarbon-based HFCs which do not contain chlorine which causes ozone depletion.
32, HFC125, HFC134a, HFC143
a, HFC152a, etc. are being studied. Any one of these refrigerants or a mixture of them is influential, and performance factors such as refrigeration capacity and efficiency, and cycle conditions such as operating pressure and temperature are similar or close to those of conventional refrigerants. Development is proceeding with a focus. This is intended to maintain the same usability as conventional refrigerant products, and to ensure that product specifications and manufacturing equipment can be shifted to new refrigerant compatible products with minimal changes from conventional products. I am aiming.

By the way, in order to cope with the new refrigerant, not only the same performance as that of the conventional product but also the compressor, the cycle auxiliary parts, and the cycle control are required to stabilize the cycle state such as the operating pressure range and the temperature at all times. Need to be able to respond to Further, when the refrigerant changes, the refrigerating machine oil also changes to a corresponding one. In other words, chlorine has the effect of promoting compatibility with oil, but as described above, the new refrigerant does not contain chlorine, which causes ozone layer depletion.
The compatibility with the conventional refrigerating machine oil mainly composed of mineral oil, alkylbenzene, etc., which has been widely used in the conventional refrigerating machine, is remarkably reduced, so that it cannot be used together with the conventional refrigerating machine oil. Therefore, a new refrigerating machine oil has been developed which ensures compatibility with a new refrigerant by a molecular polarity such as an ether type or an ester type. By the way, in the refrigeration cycle to which the new refrigerant is applied, the contamination of the chlorinated substance by the conventional refrigerant oil or the conventional refrigerant causes a chemical change of the new refrigerant or the new refrigerant oil. Cause corrosion, which significantly reduces the reliability of the product.

An object of the present invention is to provide a refrigeration apparatus which ensures the reliability of equipment and does not impair the performance.

[0008]

According to the present invention, there is provided a refrigeration apparatus comprising a scroll compressor, a condenser and a receiver, connected to an evaporator via an expansion valve. The downstream side and the scroll compressor are connected by a liquid injection pipe, and the liquid injection pipe has an injection valve or an electronic expansion valve in which the amount of liquid injection is controlled in relation to the discharge side temperature of the scroll compressor, The condenser uses a heat exchanger whose diameter is smaller than the diameter of the refrigerant pipe of the heat exchanger constituting the evaporator.

Further, the present invention provides a scroll compressor driven by a motor whose number of rotations can be controlled, a condenser, a receiver, and a liquid connecting the scroll compressor to a downstream side of the condenser. A refrigerating apparatus having an injection pipe, wherein the liquid injection pipe includes a strainer, and an injection valve or an electronic expansion valve;
The refrigerant gas compressed by the compressor is condensed by the condenser and sent to the dryer through the receiver, and the liquid refrigerant downstream of the condenser passes through a strainer and an injection valve or an electronic expansion valve. The injection valve or the electronic expansion valve is injected into the scroll compressor and its opening is controlled in relation to the discharge temperature of the scroll compressor.

[0010] In the above, it is desirable that the liquid injection pipe is connected to a lower liquid reservoir of the receiver.

Further, the present invention provides a compressor, a condenser,
In a refrigeration system for controlling the amount of liquid injection to a compressor, a liquid injection pipe connecting a liquid receiver, a condenser downstream side, and a compressor, a compressor motor for controlling the number of rotations of the compressor by inverter control. A blower for supplying external air to the condenser and a blower motor for controlling the number of rotations of the blower. When the outside air temperature is low, the rotation speed of the blower motor is reduced to reduce the number of rotations. It reduces the air volume.

Further, the present invention provides a motor capable of controlling the number of rotations.
A scroll compressor driven by a compressor, a condenser,
In a refrigeration system having a liquid receiver, a dryer, and a liquid injection pipe connecting the downstream side of the condenser and the scroll compressor, an electromagnetic valve is provided in the liquid injection pipe, and at the same time as the start of the scroll compressor, The solenoid valve is opened.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, HFC125 / HCl, which is a fluorinated hydrocarbon containing no chlorine, is used as a refrigerant for a refrigeration cycle.
HFC143a / HFC134a (weight ratio 44/52
/ 4 wt%), and a liquid injection type scroll compressor is used as the compressor. Ester oil, which is a new refrigerator oil, is used.

Hereinafter, a specific embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the refrigerating apparatus of this embodiment includes a scroll compressor 1, a condenser 2, a liquid receiver 3, a dryer 4, expansion valves 5a and 5b, evaporators 6a and 6b, a strainer 18, and an accumulator. 7 are sequentially connected to form a refrigeration cycle. In order to supply external air to the condenser 2, the blower motors 8a and 8b and the propeller fan 9 are used.
a and 9b are provided as shown in FIG.

As the refrigerant of the refrigeration cycle, a fluorinated hydrocarbon-based refrigerant containing no chlorine which causes ozone layer destruction is used. HFC32, HFC
125, HFC134a, HFC143a, HFC15
2a and the like, and any one of them is used as a single or plural mixed refrigerant. In this embodiment, the three kinds of refrigerant R125 / R143a / R134a (weight ratio 44)
/ 52/4 wt%). In addition, it is necessary to use a refrigerating machine oil used in the refrigerating cycle that is compatible with the refrigerant. In the present embodiment, an ester oil is used as the refrigerating machine oil. In particular, the refrigerating machine oil covers a temperature range of −60 ° C. to + 5 ° C., which is a general specification range of a refrigerating machine, and has a viscosity of 40 ° C. 2 to 70 at ℃
The cSt was 1 to 9 cSt at 100 ° C., and it was found that the base oil used was an ester oil of a fatty acid having at least two ester bonds in the molecule.

A refrigeration cycle using the above-mentioned three-type mixed refrigerant and refrigerating machine oil realizes a refrigerating apparatus that covers a temperature range of -60.degree. C. to + 5.degree. C., similarly to a conventional refrigerating apparatus using a refrigerant containing chlorine. In this embodiment, the following measures are taken.

A high pressure detector 31 for detecting the pressure of the high pressure pipe 24 and a low pressure detector 32 for detecting the pressure of the low pressure pipe 25 are connected to each other. A protection switch 23 for switching off the operation circuit of the machine motor is provided.

When the pressure of the condenser 2 is detected and the pressure reaches a high pressure set value, the compressor speed is reduced to reduce the compressor capacity, and when the pressure reaches a low pressure set value. A pressure control device 15 is provided to increase the compressor capacity by increasing the rotation speed of the compressor motor. The number of revolutions of the compressor motor may be controlled stepwise by using a pole number conversion motor, or may be continuously controlled according to the pressure value by inverter control. In this embodiment, when the pressure reaches the high pressure set value by the pressure control device 15, the rotation speed of the blower motors 8a and 8b is simultaneously controlled to full speed to reduce the high pressure and the pressure reaches the low pressure set value. Then, the rotation speed of the blower motors 8a and 8b is reduced to increase the high pressure.

A liquid injection pipe 12 for connecting a liquid refrigerant outlet pipe 16 of the liquid receiver 3 on the downstream side of the condenser and the scroll compressor 1 is provided. The liquid injection pipe 12 has a strainer 11 and an electronic expansion valve 10.
Are provided, through which the liquid refrigerant is scrolled.
Into the intermediate pressure chamber of the compressor 1. A control device 30 controls the electronic expansion valve 10 and the blower motors 8a and 8b. The thermistor 26 detects the liquid temperature of the condenser 2;
According to the detection values from the thermistor 27 for detecting the air suction temperature (outdoor air temperature) of the condenser 2 and the thermistor 28 for detecting the discharge side temperature of the compressor 1, the electronic expansion valve 10 is preliminarily input by a program. And blower motor 8
The control variables a and 8b are calculated. 29 is a control device 30
Is a control signal output device that outputs a control signal to the blower motors 8a and 8b for the condenser and the electronic expansion valve 10 in response to a command from the controller.

The condenser 2 uses a heat exchanger whose diameter is smaller than the diameter of the refrigerant pipes of the heat exchangers constituting the evaporators 6a and 6b. In this embodiment, a small diameter heat exchanger having a diameter of about 7 mm is used for the condenser 2 in order to cover the temperature range of the refrigerating apparatus.

A bypass pipe 22 is connected to the discharge gas pipe 13.
And the evaporator 6 is connected via the solenoid valve 20 and the check valve 21.
a, 6b are connected to outlet pipes (refrigerant gas pipes) 17; This is to release the high-pressure gas to the low-pressure side before starting the compressor 1, and to open the solenoid valve 20 for a certain period of time.
It is assumed that. Thereby, the cycle pressures on the high pressure side and the low pressure side can be balanced, and the compressor 1 can be started smoothly.

Next, the operation of this embodiment will be described with reference to FIG. The refrigerant gas compressed by the compressor 1 is supplied to the discharge pipe 13,
It is condensed in the condenser 2 through the check valve 14, passes through the liquid receiver 3, the refrigerant liquid pipe 16, and the dryer 4, is sent to the expansion valves 5a, 5b, and the evaporators 6a, 6b, evaporates to gas, and the refrigerant gas It returns to the suction side of the compressor 1 from the suction pipe 19 through the pipe 17, the strainer 18, and the accumulator 7.

The liquid injection pipe 12 will be described. The opening degree of the electronic expansion valve 10 is controlled by the discharge-side temperature of the compressor 1. The set value of the discharge temperature input in advance by the detection of the thermistor 28 is compared with the detected discharge temperature. If the set temperature is higher than the set value, the opening of the valve 10 is increased, and if it is lower, the opening is reduced. That is, the expansion valve 10 is continuously controlled by the control device 30 and the control signal output device 29.
Adjust the opening of. Thus, by controlling the discharge-side temperature of the compressor 1, overheating can be prevented and stable refrigeration cycle operation can be performed.

When the outside air temperature is low, the amount of the refrigerant dissolved in the refrigerating machine oil increases, so that the viscosity of the refrigerating machine oil decreases. For this reason, the effect as a lubricating oil for the bearing portion of the compressor is reduced, and the bearing portion is worn. In the present embodiment, when the outside air temperature is lower than a certain set temperature, the opening of the electronic expansion valve 10 of the liquid injection pipe 12 is reduced by the detection of the thermistor 27 to increase the viscosity of the oil even slightly. The amount of the refrigerant is reduced, the discharge-side temperature at the time of starting the compressor is increased, and the amount of the refrigerant dissolved into the refrigerating machine oil is reduced to secure the viscosity of the refrigerating machine oil. Thereby, the reliability of the compressor bearing can be improved.

When the outside air temperature is high, the high-pressure side pressure increases, so that the high-pressure pressure is controlled. That is, thermistor 2
If the temperature of the liquid refrigerant at the outlet of the condenser 2 is high as a result of the detection at 6, the number of rotations of the blower motors 8a and 8b for the condenser is increased to increase the amount of blown air to lower the high pressure. When the outlet liquid refrigerant temperature of the condenser 2 is low, the number of rotations of the condenser blower motors 8a and 8b is reduced and the high pressure is increased.

Further, the detection of the thermistor 27 allows the blower motors 8a, 8b for the condenser to be used even when the outside air temperature is high.
The high pressure is reduced by increasing the number of revolutions and increasing the amount of air blow, and reducing the amount of air blow to increase the high pressure when the outside air temperature is low.

These controls are performed by controlling the number of rotations of the blower motors 8a and 8b by the control device 30 and the control signal output device 29.

When the pressure of the condenser 2 becomes higher than the set value, the capacity of the scroll compressor 1 is reduced by operating the pressure control device 15, and the blower motors 8a and 8a are controlled. The rotation speed of 8b is set to full speed to reduce the high pressure. Even when the pressure of the condenser 2 becomes lower than the set value, the capacity of the scroll compressor 1 is increased by the operation of the pressure control device 15, and the rotation speeds of the blower motors 8a and 8b are also reduced. Control to increase pressure.

The liquid receiver 3 is provided with a fusible plug 33 having a function of releasing the refrigerant when the refrigerant is overheated.

The dryer 4 is intended to remove moisture when it enters the refrigeration cycle. In the refrigeration cycle using a fluorinated hydrocarbon-based refrigerant containing no chlorine as a working refrigerant, the desiccant used for the dryer 4 is a fluorinated hydrocarbon containing no chlorine containing pores reaching the molecular adsorption cavity in the crystal structure. It is composed of a synthetic zeolite of 3.3 Å or less, which is smaller than the molecule of the system refrigerant and larger than the molecule of water. The mounting position of the dryer 4 may be installed in the oil sump in the compressor 1, the oil sump of the oil separator, or the inside of the accumulator 7. In this case, the number of parts is smaller than when connected to the refrigeration cycle piping. Can be reduced, the production cost can be reduced, and gas leakage due to improper mounting can be reduced.

In the refrigerating cycle, thermistors 26 to 28 are used as temperature detecting means, but ON / OFF control by a thermostat may be used instead of the thermistor. If a thermistor is used, continuous control is possible, but if a thermostat is used, ON / OFF control is performed. Further, control can be performed by the control device 30 and the control signal output device 29 by performing pressure detection instead of temperature detection.

Next, another example of the liquid injection portion in the embodiment shown in FIG. 1 will be described with reference to FIGS. In the example of FIG. 2, the liquid injection control is performed by the electromagnetic valves 34a and 34b and the capillaries 35a and 35b. Solenoid valve 3 at the same time as compressor 1 starts
4a is opened to prevent the compressor 1 discharge side temperature rise.
Further, when the discharge-side temperature becomes higher, the temperature is detected by the thermistor 28 and compared with the set temperature.
By increasing the liquid injection amount, overheating of the compressor 1 can be prevented.

Next, the example of FIG. 3 will be described. The difference from FIG. 2 is that the connection position of the liquid injection pipe 12 is
It is connected to the lower reservoir of the liquid receiver 3. This makes it possible to always use the liquid refrigerant stably for liquid injection control.

Next, the example of FIG. 4 will be described. The only difference from the example of FIG. 1 is the liquid injection control.
In the example of FIG. 4, the liquid injection control is performed by using the line of the injection valve 36 and the line of the solenoid valve 34a and the line of the capillary 35a. At the same time as the compressor 1 is started, the solenoid valve 34a is opened to prevent the discharge-side temperature of the compressor 1 from rising. Further, when the temperature or the pressure is higher than the set temperature or pressure by the temperature or pressure detection 37 connected to the discharge pipe 13, the injection valve 36 is opened. Thereby, the overheating prevention operation of the compressor 1 is performed, and the stable refrigeration cycle operation can be performed.

Next, the example of FIG. 5 will be described. What is different from the example of FIG. 4 is that the connection position of the liquid injection pipe 12 is connected to the lower liquid reservoir of the receiver 3 so that the liquid refrigerant can always be used for liquid injection control without shortage. it can.

[0036]

As described above, according to the present invention, a stable refrigeration cycle operation can be realized over a wide range of operating pressures and temperatures.

[Brief description of the drawings]

FIG. 1 is a system diagram of a refrigeration apparatus showing one embodiment of the present invention.

FIG. 2 is a main part system diagram showing another example of the liquid injection component in FIG. 1;

FIG. 3 is a main part system diagram showing still another example of the liquid injection component in FIG. 1;

FIG. 4 is a main part system diagram showing still another example of the liquid injection component in FIG. 1;

FIG. 5 is a main part system diagram showing still another example of the liquid injection component in FIG. 1;

[Explanation of symbols]

1 ... Compressor, 2 ... Condenser, 3 ... Receiver, 4 ... Dryer,
6a, 6b: evaporator, 7: accumulator, 8a, 8
b: blower motor, 9a, 9b: propeller fan, 10
... Electronic expansion valve, 15 ... Pressure switch, 26 ... Thermistor for detecting condenser liquid temperature, 27 ... Thermistor for detecting outside air temperature,
28: a thermistor for detecting the compressor discharge side temperature; 29: a control signal output device; 30: a control device; 34a, 34b: a solenoid valve; 35a, 35b: a capillary; 36: an injection valve; 37: a temperature or pressure detecting device.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F25B 39/04 F25B 39/04 Z 41/04 41/04 E

Claims (5)

[Claims] 1. A refrigerating apparatus comprising a scroll compressor, a condenser, and a receiver, connected to an evaporator via an expansion valve, wherein a downstream side of the condenser and the scroll compressor are connected by a liquid injection pipe. Connected to the liquid injection pipe, has an injection valve or an electronic expansion valve in which the amount of liquid injection is controlled in relation to the discharge side temperature of the scroll compressor, and the condenser is a heat source constituting the evaporator. A refrigeration system using a heat exchanger having a diameter smaller than the diameter of a refrigerant pipe of the exchanger. 2. A scroll compressor driven by a motor whose rotation speed can be controlled, a condenser, a receiver, and a liquid injection pipe connecting the scroll compressor with a downstream side of the condenser. Wherein the liquid injection pipe comprises a strainer, an injection valve or an electronic expansion valve, and the refrigerant gas compressed by the scroll compressor is condensed by the condenser and the refrigerant gas is condensed by the condenser. It is sent to the dryer through the receiver,
The liquid refrigerant downstream of the condenser is injected into the scroll compressor via the strainer and the injection valve or electronic expansion valve, and the injection valve or electronic expansion valve is connected to the scroll compressor. A refrigerating apparatus characterized in that its opening is controlled in relation to the discharge temperature of a compressor. 3. The refrigerating apparatus according to claim 2, wherein a liquid injection pipe is connected to a lower liquid reservoir of the liquid receiver. 4. A compressor, a condenser, a receiver, a liquid injection pipe connecting the downstream side of the condenser and the compressor, and a refrigerating device for controlling an amount of liquid injection to the compressor. , A compressor motor for controlling the rotation speed of the compressor by inverter control, a blower for supplying external air to the condenser, and a blower motor for controlling the rotation speed therefor, A refrigeration system in which when the temperature is low, the number of rotations of the blower motor is reduced to reduce the amount of blown air. 5. A scroll compressor driven by a motor whose rotation speed can be controlled, a condenser, a receiver, a dryer, a downstream side of the condenser and the scroll compressor. A liquid refrigerating apparatus comprising: a liquid injection pipe; and an electromagnetic valve provided in the liquid injection pipe, and the electromagnetic valve is opened when the scroll compressor is started.