JP2003013860A - Two stage compression type compressor and refrigerating device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two stage compression type compressor capable of controlling pressure of a refrigerant discharged from the compressor and a refrigerating device using the same. SOLUTION: In the two stage compression type compressor 1 having a structure compressing a low pressure refrigerant to a medium pressure in a first stage and compressing a medium pressure refrigerant to high pressure in a second stage and discharging the same, a supply circuit L5 supplying the low pressure refrigerant to a suction port 17A of the second stage is provided, the refrigerant of low pressure P0 is compressed and discharged in both of the first stage 15 and the second stage 17 when the supply circuit L5 is operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage compression type compressor and a refrigeration system using the same.

[0002]

2. Description of the Related Art Generally, a refrigerating apparatus having a refrigerating cycle having a compressor, a high temperature side heat exchanger, a pressure reducing device and an evaporator is known.

[0003] In this type, conventionally, a CFC containing chlorine (HCFC22 or the like) was used as a refrigerant in the refrigeration cycle, but its use is being regulated from the viewpoint of protecting the ozone layer, and as a substitute refrigerant therefor. Because of its high global warming potential even with CFCs containing no chlorine (HCF), it was designated as a regulated substance at the Kyoto Conference on Global Warming Prevention (COP3).

Therefore, instead of a compound such as CFC,
There has been an increasing movement to use substances existing in the natural world as refrigerants in refrigeration cycles, and in particular, studies have been conducted on the use of CO ₂ refrigerants in refrigeration cycles.

When this CO ₂ refrigerant is used, the high pressure side of the refrigeration cycle becomes supercritical
Therefore, a high coefficient of performance (COP) can be expected in a heating process in which the temperature rise range of water is large, such as hot water supply in a heat pump water heater.

On the other hand, on the other hand, the refrigerant must be compressed to a high pressure, and in recent years, the refrigerant compressed to the intermediate pressure at the first stage is introduced into the second stage through the shell case in the compressor. Therefore, an internal intermediate pressure two-stage compression type compressor having a structure in which this intermediate pressure refrigerant is compressed to a high pressure and discharged is adopted.

In this type, there is a case where the discharge pressure of the compressor does not always have to be maintained at a high pressure depending on the usage form.

[0008]

However, in the conventional two-stage compression type compressor, the discharge pressure of the compressor cannot be adjusted, which may cause inconvenience.

For example, when the two-stage compression type compressor is used for a refrigerating apparatus and the refrigerating apparatus is installed outdoors, the defrosting operation of the evaporator is required in winter and the like. In the defrosting operation in this case, since the pressure difference between the high and low pressures of the refrigerant is not required, there is a problem that the defrosting efficiency decreases when the refrigerant is compressed in two stages.

Therefore, an object of the present invention is to provide a two-stage compression type compressor and a refrigeration system using the same which can solve the problems of the above-mentioned conventional techniques and can adjust the pressure of the refrigerant discharged from the compressor. To do.

[0011]

To achieve the above object, the invention according to claim 1 compresses a low-pressure refrigerant to an intermediate pressure in the first stage and compresses an intermediate-pressure refrigerant to a high pressure in the second stage. In a two-stage compression type compressor having a structure for discharging by discharging, a supply circuit for supplying low-pressure refrigerant to the suction port of the second stage is provided, and when this supply circuit is operated, both the first stage and the second stage are operated. A feature is that the low-pressure refrigerant is compressed and discharged.

According to a second aspect of the present invention, the two-stage compression type compressor has a structure in which the low-pressure refrigerant is compressed to an intermediate pressure in the first stage and the intermediate-pressure refrigerant is compressed to a high pressure in the second stage and discharged. In the refrigerating apparatus including, a supply circuit for supplying low-pressure refrigerant to the second-stage suction port is provided, and when the supply circuit is operated, the compressor is a low-pressure refrigerant for both the first and second stages. Is configured to be compressed and discharged.

According to a third aspect of the present invention, in the second aspect, when the compressor compresses and discharges low-pressure refrigerant in both the first and second stages, the discharged refrigerant is supplied to the evaporator. It has a defrosting circuit for

The invention according to claim 4 is the invention according to claim 2 or 3.
In the described one, a CO ₂ refrigerant is used as the refrigerant.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a heat pump device using a two-stage compression type rotary compressor. Reference numeral 1 denotes a compressor. In the compressor 1, a solenoid valve 2, a gas cooler (high pressure side heat exchanger) 3, an internal heat exchanger 4, a pressure reducing device (expansion valve) are provided through a refrigerant pipe L1 indicated by a broken line. 5, and an evaporator (low-pressure side heat exchanger) 7 via a refrigerant pipe L2 indicated by a solid line
Are sequentially connected to form a refrigeration cycle.

The low-pressure side refrigerant pipe L3 shown by the solid line returning from the evaporator 7 to the compressor 1 passes through the internal heat exchanger 4, and the low-pressure refrigerant exchanges heat with the high-pressure refrigerant passing through the gas cooler 3 to change the temperature of the refrigerant. It is raised to increase the degree of superheat and returned to the compressor 1.

A CO ₂ refrigerant is used in this refrigeration cycle. Since the CO ₂ refrigerant has an ozone depletion potential of 0 and a global warming potential of 1, it has a low environmental load, is neither toxic nor flammable, and is safe and inexpensive. When this CO ₂ refrigerant is used, the high-pressure side of the refrigeration cycle becomes a transcritical cycle (Transcritical Cycle), which is supercritical, and is therefore high in a heating process in which the temperature rise range of water is large, such as hot water supply in a heat pump water heater. You can expect a coefficient of performance (COP).

On the other hand, however, the refrigerant must be compressed to a high pressure, and the compressor 1 employs an internal intermediate pressure two-stage compression type compressor.

As shown in FIG. 2, this internal intermediate pressure two-stage compression type compressor 1 has a motor case 1 inside a shell case 11.
2 and a compression unit 13 driven by this electric motor unit 12. The compression unit 13 has a two-stage compression structure, and includes a first-stage compression unit 15 and a second-stage compression unit 1.
It consists of 7.

During normal operation, the low-pressure P0 refrigerant sucked into the suction port 15A of the first-stage compression section 15 through the first suction pipe L4 is compressed to the intermediate pressure P1 by the compression section 15, Discharge port 15B to shell case 11
After being discharged into the shell case 11 and passing through the shell case 11, the pipe 21
Through to the three-way valve 23. In this three-way valve 23, the port 23a and the port 23b communicate with each other, and the refrigerant is the refrigerant pipe L6.
Through the suction port 17A of the second-stage compression section 17, is compressed to a high pressure P2 by the compression section 17, and is discharged from the discharge port 17B.

In the present embodiment, the suction port 1 of the second stage
A second suction pipe (supply circuit) L5 for supplying the low-pressure P0 refrigerant to 7A is provided, and this second suction pipe L is also provided.
5, a solenoid valve 25 is provided.

In this compressor 1, when the solenoid valve 25 is closed and the ports 23a and 23b of the three-way valve 23 are communicated with each other, the refrigerant is compressed into the high pressure P2 by the two-stage compression and discharged, while the solenoid valve When 25 is opened and the ports 23a and 23c of the three-way valve 23 communicate with each other, the compression strokes become parallel, and the low-pressure refrigerant P0 is compressed to the intermediate pressure P1 in both the first and second stages and discharged.

According to this, since the discharge pressure of the compressor 1 is controlled in two steps, it becomes possible to follow changes in the manner of use as compared with the conventional case.

The gas cooler 3 comprises a refrigerant coil 9 in which a CO ₂ refrigerant flows and a water coil 10 in which water flows,
The water coil 10 is connected to a hot water storage tank (not shown) via a water pipe. A circulation pump (not shown) is connected to the water pipe, and the circulation pump is driven to circulate the water in the hot water storage tank through the gas cooler 3, where it is heated and stored in the hot water storage tank.

Since this heat pump device is installed outdoors as a heat pump unit, it is necessary to remove the frost adhering to the evaporator 7.

In this embodiment, as shown in FIG. 1, a defrosting solenoid valve 31 for guiding the refrigerant discharged from the compressor 1 to the evaporator 7 by bypassing the gas cooler 3 and the pressure reducing device 5, Hot gas defrosting circuit 33 including bypass pipe L7
Is provided.

In this defrosting operation, first, the solenoid valve 2 provided on the discharge side of the compressor 1 is closed by a controller (not shown), and the normally closed defrosting electromagnetic valve 31 is opened. The solenoid valve 25 attached to the compressor 1 is opened, and the port 23a and the port 23c of the three-way valve 23 are connected. When the compressor 1 is driven in this state, the compression strokes are parallel, so that the low-pressure refrigerant P0 in both the first and second stages
Are compressed to the intermediate pressure P1 and discharged.

The refrigerant discharged in the first stage is supplied to the evaporator 7 via the bypass pipe L7, the electromagnetic valve 31 for defrosting, and the refrigerant pipe L2, and the refrigerant discharged in the second stage passes through the pipe line 21 and is a three-way valve. 23, the port 23a of the three-way valve 23, the port 23c, the refrigerant pipe L8, the refrigerant pipe L2, and the evaporator 7 to heat the evaporator 7 for defrosting. Be seen.

During the defrosting operation, since the pressure difference between the high and low pressures of the refrigerant is not required, the defrosting efficiency is lowered when the refrigerant is compressed in two stages.

In the present embodiment, during normal heat pump operation, the compressor 1 uses its two-stage compression to increase its discharge pressure to the high pressure P2.
However, since the compressor 1 is switched to the parallel one-stage compression during the defrosting operation, the discharge gas amount of the intermediate pressure P1 from the compressor 1 increases, so that the defrosting effect is enhanced. It is possible to open the solenoid valve 2 provided on the discharge side of the compressor 1 during the defrosting operation.

According to this, the intermediate pressure P during defrosting operation
Since one refrigerant is guided to the gas cooler 3, the temperature decrease of the gas cooler 3 during the defrosting operation is reduced, and the time until the normal operation is resumed can be shortened.

On the other hand, in this type of compressor 1, the mixing ratio of the refrigerating machine oil contained in the refrigerant of intermediate pressure P1 discharged in the first stage and the refrigeration contained in the refrigerant of high pressure P2 discharged in the second stage. The mixing ratio differs from the mixing ratio of machine oil. That is, the mixing ratio of oil contained in the refrigerant of intermediate pressure P1 is generally smaller than the mixing ratio of oil contained in the refrigerant of high pressure P2.

In this embodiment, from the compressor 1 to the high pressure P2
Since the refrigerant is not discharged, the amount of oil discharged during the defrosting operation is reduced, a sufficient amount of oil remaining in the shell case is secured, and the durability of the compressor 1 can be improved.

Although the present invention has been described above based on the embodiment, it is obvious that the present invention is not limited to this.

In the above structure, all the refrigerant discharged from the first stage of the compressor 1 is supplied to the second stage through the shell case 11. However, the present invention is not limited to this, and a part of the refrigerant is supplied to the shell case 11. Alternatively, a configuration may be adopted in which the rest is directly supplied from the first-stage discharge port to the second-stage suction port.

[0037]

According to the present invention, the low-pressure refrigerant is compressed to the intermediate pressure in the first stage, and the intermediate-pressure refrigerant is compressed to the high pressure in the second stage and discharged, and the two-stage compression type compressor. In the refrigerating apparatus using, the pressure of the refrigerant discharged from the compressor can be adjusted.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a refrigeration system according to the present invention.

FIG. 2 is a sectional view of a compressor.

[Explanation of symbols]

1 compressor 3 gas cooler 5 decompression device 7 evaporator 11 shell case 13 Compressor 15 First stage compression unit 17 Second stage compression unit 17A Second stage suction port L5 Second suction pipe (supply circuit) 25 solenoid valve 31 Defrosting solenoid valve 33 Hot gas defrosting circuit P0 low pressure P1 intermediate pressure P2 high pressure

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F25B 47/02 F25B 47/02 F (72) Inventor Toshikazu Ishihara 2-5 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (72) Inventor Hiroshi Mukai 2-5-5 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Denki Co., Ltd. (72) Takayasu Saito 2 Keihan Hondori, Moriguchi City, Osaka Prefecture 5th-5th Sanyo Electric Co., Ltd. F term (reference) 3H003 AA05 AC03 CD05 CF01 3H029 AA04 AA13 AB03 BB42 BB53 CC02 CC06 CC24 CC25 CC26 CC32 3H076 AA16 BB34 CC07 CC44 CC91

Claims (4)

[Claims] 1. The first stage compresses a low-pressure refrigerant to an intermediate pressure,
In a two-stage compression type compressor having a structure in which a medium-pressure refrigerant is compressed to a high pressure and discharged in a second stage, a supply circuit for supplying a low-pressure refrigerant to the second-stage suction port is provided, and this supply circuit When operated, the two-stage compression type compressor is characterized in that the low-pressure refrigerant is compressed and discharged in both the first and second stages. 2. The low pressure refrigerant is compressed to an intermediate pressure in the first stage,
In a refrigerating apparatus including a two-stage compression type compressor having a configuration in which a medium-pressure refrigerant is compressed to a high pressure and discharged in a second stage, a supply circuit that supplies low-pressure refrigerant to the second-stage suction port is provided. A refrigerating apparatus, wherein when the supply circuit is operated, the compressor compresses and discharges low-pressure refrigerant in both the first and second stages. 3. A defrosting circuit for supplying the discharged refrigerant to an evaporator when the compressor compresses and discharges a low-pressure refrigerant in both the first and second stages. Two
The refrigeration system described. 4. The refrigerating apparatus according to claim ₂ , wherein a CO ₂ refrigerant is used as the refrigerant.