JPH05215420A - Double-staged compression freezing cycle apparatus - Google Patents

Abstract

PURPOSE:To prevent complication of control and increase of cost by a method wherein a single expansion valve can control a cooling state or superheat degree of suction of a low stage side compressor part at a time of cooling and heating operation. CONSTITUTION:To a refrigerant compressor 1 formed of a low stage side compressor part 1a and a high stage side compressor part 1b, a flow passage switching valve 2, an outdoor heat exchanger 3, a pressure reducer 8, a gas- liquid separator 5, and an indoor heat exchanger 6 are connected. A bypass circuit 7 to connect a gas outlet of the gas-liquid separator 5 and an intake side of the high stage side compressor part 1b is provided. Thus a freezing cycle is formed. The pressure reducer 8 is formed of check valves 8d, 8e, 8f and 8g and capillary tubes 8a and 8b, all connected to form a bridge, so that refrigerant can flow through the gas-liquid separator 5 at the time of heating and cooling. Further, an expansion valve 8c is provided between a flowout side of the gas-liquid separator and a flowout end of the bridge.

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 refrigeration cycle device.

[0002]

2. Description of the Related Art As a conventional two-stage compression refrigeration cycle apparatus, as shown in FIG. 2, a bypass circuit is provided which connects a gas outlet of a gas-liquid separator and a suction side of a high-stage compressor. It was configured (for example, Japanese Patent Laid-Open No. 2-10062).

The conventional two-stage compression refrigeration cycle apparatus will be described below with reference to the drawings. FIG. 2 is a conventional two-stage compression refrigeration cycle diagram.

In the figure, reference numeral 1 is a low-stage compressor section 1.
and a high-stage side compressor section 1b connected in series with the low-stage side compressor section 1a. A four-way valve 2 (flow path switching valve) for switching control between cooling operation and heating operation is connected to the refrigerant compression device 1, and the outdoor heat exchanger 3 and the first expansion valve 4a are connected to the four-way valve 2.
The gas-liquid separator 5, the second expansion valve 4b, and the indoor heat exchanger 6 are sequentially connected in an annular shape, and the bypass circuit 7 is provided at the gas outlet of the gas-liquid separator 5 and the suction side of the high-stage compressor section 1b. Connect to form a refrigeration cycle.

In this two-stage compression type refrigeration cycle apparatus, the refrigerant flows in the direction of the solid line during the cooling operation and the defrosting operation. That is, the refrigerant gas discharged from the refrigerant compression device 1 passes through the cooling / heating switching four-way valve 2 and flows into the outdoor heat exchanger 3 to be liquefied, and the first expansion valve 4a, the gas-liquid separator 5,
It returns to the refrigerant compression device 1 through the second expansion valve 4b, the indoor heat exchanger 6, and the cooling / heating switching four-way valve 2. On the other hand, the refrigerant gas separated by the gas-liquid separator 5 is mixed with the refrigerant gas discharged from the low-stage compressor section 1a through the bypass circuit 7 and sucked into the high-stage compressor section 1b.

Next, in this two-stage compression refrigeration cycle apparatus, during the heating operation, the cooling / heating switching four-way valve 2 changes the flow of the refrigerant in the direction of the broken line. That is, the refrigerant gas discharged from the refrigerant compression device 1 passes through the cooling / heating switching four-way valve 2 and flows into the indoor heat exchanger 6 to be liquefied, and the second expansion valve 4b, the gas-liquid separator 5, and the first expansion valve. It returns to the refrigerant compression device 1 through the valve 4a, the outdoor heat exchanger 3, and the cooling / heating switching four-way valve 2. On the other hand, the refrigerant gas separated by the gas-liquid separator 5 is mixed with the refrigerant gas discharged from the low-stage compressor section 1a through the bypass circuit 7 and sucked into the high-stage compressor section 1b.

[0007]

However, in the operation control method of the conventional two-stage compression refrigeration cycle apparatus described above,
There were the following issues.

That is, when the cooling operation (or the defrosting operation) is performed, the flow direction of the refrigerant is reversed from that in the heating operation, so that the refrigerant state of the suction of the low-stage compressor portion 1a during the cooling and heating operation, for example, the degree of superheat In order to perform the control, since the first expansion valve 4a is used in the heating operation and the second expansion valve 4b is used in the cooling operation, two electric expansion valves are required, which complicates the control and increases the cost. I had.

The present invention solves the above-mentioned problems of the conventional example, and controls the suction state of the suction of the low-stage compressor section, for example, the degree of superheat, during the heating and cooling operation by using the most expensive expansion valve. The purpose is to prevent the control from becoming complicated and the cost from increasing.

[0010]

In order to solve the above-mentioned problems, a two-stage compression refrigeration cycle apparatus of the present invention comprises a low-stage compressor section and a high-stage side connected in series with the low-stage compressor section. A refrigerant compression device composed of a compressor part, a flow path switching valve, an outdoor heat exchanger, a pressure reducing device, a gas-liquid separator and an indoor heat exchanger are connected, and a gas outlet part of the gas-liquid separator and A refrigeration cycle is configured by providing a bypass circuit that connects the suction side of the high-stage compressor section, and the decompression device has a check valve and a check valve so that the refrigerant flows to the gas-liquid separator during heating operation and cooling operation. The capillary tube forms a bridge, and an expansion valve is provided between the outflow side of the gas-liquid separator and the outflow end of the bridge.

[0011]

The present invention has the following actions by the above means. That is, with the two-stage compression type refrigeration cycle device having the decompression device having the above-mentioned configuration, the superheat degree control of the suction of the refrigerant compression device during the cooling and heating operation can be performed by one expansion valve.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, those having the same functions as those of the conventional one shown in FIG.

An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a two-stage compression refrigeration cycle according to an embodiment of the present invention. In the figure, the low-stage compressor section 1
a and a low-stage compressor section 1a and a high-stage compressor section 1b connected in series, a four-way valve (flow path switching valve) 2 for controlling switching between cooling operation and heating operation. , Outdoor heat exchanger 3, gas-liquid separator 5, indoor heat exchanger 6, gas outlet of gas-liquid separator 5 and high-stage compressor section 1b
The bypass circuit 7 connecting the suction side of the has the same function as the conventional one.

The present invention is different from the conventional example in the pressure reducing device 8. The decompression device 8 includes a first and a second capillary tubes 8a and 8b, an electric expansion valve 8c, and a first check valve 8
d, the second check valve 8e, the third check valve 8f, and the fourth check valve 8g, and the first to fourth check valves 8d and 8d.
e, 8f and 8g are connected in a rhombus, a first capillary tube 8a is provided on the inlet side of the first check valve 8d, and a second capillary tube 8b is provided on the inlet side of the second check valve 8e. And form a bridge. An electric expansion valve 8c is provided between the diagonal outflow end 8h on one side of the rhombus bridge and the outflow side of the gas-liquid separator 5, and one end of the diagonal line on the other side of the rhombus is connected to the outdoor heat exchanger 3. The indoor heat exchanger 6 is connected to the other end of the diagonal line on the other side of the rhombus.

Next, the heating operation of this two-stage compression refrigeration cycle system will be described. During heating operation, the refrigerant flows in the direction of the broken line. That is, the refrigerant gas discharged from the refrigerant compression device 1 passes through the cooling / heating switching four-way valve 2, flows into the indoor heat exchanger 6, is liquefied, and is depressurized to an intermediate pressure by the second capillary tube 8b. Is separated into gas and liquid by the gas-liquid separator 5 through the check valve 8e, the refrigerant liquid is further reduced in pressure by the electric expansion valve 8c, and is gasified by the outdoor heat exchanger 3 through the third check valve 8f. , And returns to the refrigerant compression device 1 through the air-conditioning switching four-way valve 2. On the other hand, the refrigerant gas separated by the gas-liquid separator 5 is mixed with the refrigerant gas discharged from the low-stage compressor section 1a through the bypass circuit 7 and sucked into the high-stage compressor section 1b.

Since the electric expansion valve 8c is located downstream of the second capillary tube 8b, it is possible to control the degree of superheat of suction of the low pressure side compressor section 1a by the opening degree of the electric expansion valve 8c.

Next, the cooling operation (or defrosting operation) will be described. During the cooling operation, the cooling / heating switching four-way valve 2 changes the flow of the refrigerant to the solid line direction. That is, the refrigerant gas discharged from the refrigerant compression device 1 passes through the cooling / heating switching four-way valve 2 and flows into the outdoor heat exchanger 3 to be liquefied, and is depressurized to an intermediate pressure by the first capillary tube 8a. Is separated into gas and liquid in the gas-liquid separator 5 through the check valve 8d, the refrigerant liquid is further depressurized to a low pressure by the electric expansion valve 8c, and is gasified in the indoor heat exchanger 6 through the fourth check valve 8g. Then, it returns to the refrigerant compression device 1 through the air-conditioning switching four-way valve 2.

Since the electric expansion valve 8c is located downstream of the first capillary tube 8a even during the cooling operation, the degree of superheat of the suction of the low-stage compressor section 1a is controlled by the opening of the electric expansion valve 8c. Can be controlled.

Although the four-way valve is used as the flow path switching control means in the above embodiment, a two-way valve, a three-way valve or another switching device may be used.

[0020]

The two-stage compression type refrigerating cycle apparatus of the present invention is provided with a heating / cooling system by providing a decompression device with a capillary tube, a check valve forming a bridge, and an expansion valve during cooling operation or defrosting operation. The superheat control of the suction of the refrigerant compressor during operation can be performed with one expansion valve, and the control can be simplified and the cost can be reduced as compared with the conventional method using two electric expansion valves. You can

[Brief description of drawings]

FIG. 1 is a two-stage compression refrigeration cycle diagram showing an embodiment of the present invention.

FIG. 2 is a conventional two-stage compression refrigeration cycle diagram.

[Explanation of symbols]

 1 Refrigerant compressor 1a Low-stage compressor section 1b High-stage compressor section 2 Cooling / heating switching four-way valve (flow path switching valve) 3 Outdoor heat exchanger 5 Gas-liquid separator 6 Indoor heat exchanger 7 Bypass circuit 8 Pressure reduction Device 8a First capillary tube 8b Second capillary tube 8c Expansion valve 8d First check valve 8e Second check valve 8f Third check valve 8g Fourth check valve 8h Outflow end of bridge

Claims (1)

[Claims] 1. A refrigerant compression device comprising a low-stage compressor section and a high-stage compressor section connected in series with the low-stage compressor section, a flow path switching valve, an outdoor heat exchanger, A refrigeration cycle is configured by connecting a decompression device, a gas-liquid separator and an indoor heat exchanger, and providing a bypass circuit connecting the gas outlet of the gas-liquid separator and the suction side of the high-stage compressor section. The decompression device forms a bridge with a check valve and a capillary tube so that the refrigerant flows through the gas-liquid separator during heating operation and cooling operation, and between the outflow side of the gas-liquid separator and the outflow end of the bridge. A two-stage compression type refrigeration cycle device characterized in that an expansion valve is provided in the.