JPH05203271A - Two-stage compression type refrigerating cycle apparatus - Google Patents

Abstract

PURPOSE:To prevent complication of control and an increase in a cost by controlling a suction refrigerant state of a low stage side compressor section at the time of room cooling/heating with one expansion valve. CONSTITUTION:A passage transfer valve 2, an outdoor heat exchanger 3, a pressure reducing unit 4a, a gas/liquid separator 5, a capillary tube and an indoor heat exchanger 6 are connected to a refrigerant compressor 21 having a low stage side compressor section 1a and a high stage side compressor section 1b, a bypass circuit 7 for connecting a gas outlet of the separator 5 to a suction side of the compressor section 1b is provided, and a switching unit 8 is provided in the circuit 7 to constitute a refrigerating cycle. It has switching unit control means 9 for closing the unit 8 at the time of room cooling and opening it at the time of room heating.

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 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 refrigeration cycle, during the cooling operation (or during the defrosting operation), the refrigerant flows in the direction of the solid 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 outdoor heat exchanger 3 to be liquefied, and the first expansion valve 4a, the gas-liquid separator 5, and the second expansion valve. Return to the refrigerant compression device 1 through the 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, during the heating operation, the flow of the refrigerant is changed to the direction of the broken line by the cooling / heating switching four-way valve 2. 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, the above-mentioned conventional two-stage compression refrigeration cycle apparatus has the following problems.

That is, during cooling operation (or defrosting operation)
Since the flow direction of the refrigerant is reversed in the case of heating operation,
In order to control the refrigerant state (for example, the degree of superheat) of the suction of the low-stage compressor section 1a during the heating / cooling operation, the first expansion valve 4a is used in the heating operation, and the second expansion valve 4b is used in the cooling operation. This requires individual electric expansion valves, which complicates control and increases costs.

The present invention solves the above-mentioned problems of the conventional example, and controls the refrigerant state of the suction of the low-stage compressor section during the cooling and heating operation by one expansion valve, which complicates the control. ,
The purpose is to prevent an increase in cost.

[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 section is connected to a flow path switching valve, an outdoor heat exchanger, a pressure reducing device, a gas-liquid separator, a capillary tube and an indoor heat exchanger, and a gas of the gas-liquid separator. A refrigeration cycle is configured by providing a bypass circuit that connects the outlet side and the suction side of the high-stage compressor section, and a switching device is provided in the bypass circuit to close the switching device during cooling operation and during heating operation. It has opening and closing device control means.

[0011]

The present invention has the following actions due to the above-mentioned configuration. That is, by the two-stage compression refrigeration cycle device, the second expansion valve is a capillary tube, and the bypass circuit connecting the gas outlet of the gas-liquid separator and the suction side of the high-stage compressor is closed during the cooling operation. In the pressure reducing device, the refrigerant state (superheat degree) of the suction of the low-stage compressor section can be controlled 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. , The outdoor heat exchanger 3, the electric expansion valve 4a, the gas-liquid separator 5, the indoor heat exchanger 6, the bypass port 7 connecting the gas outlet of the gas-liquid separator 5 and the suction side of the high-stage compressor section 1b. Has the same function as the conventional one.

In this embodiment, a capillary tube 4b is provided in the circuit between the gas-liquid separator 5 and the indoor heat exchanger 6, an electromagnetic opening / closing valve (opening / closing device) 8 is provided in the bypass circuit 7, and An opening / closing device control means 9 for controlling the electromagnetic opening / closing valve 8 according to the operation mode is provided.

First, the heating operation of this two-stage compression refrigeration cycle apparatus will be described. During the heating operation, the opening / closing control means 9 opens the electromagnetic opening / closing valve 8. 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 and flows into the indoor heat exchanger 6, is liquefied, and is depressurized to an intermediate pressure by the capillary tube 4b, and then the gas-liquid separator 5 is discharged. Is separated into gas and liquid, and the refrigerant liquid is further reduced in pressure by the electric expansion valve 4a, gasified in the outdoor heat exchanger 3, and returned to the refrigerant compression device 1 through the four-way valve 2 for switching between heating and cooling. 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 is sucked into the high-stage compressor section 1b. In this heating operation, the electric expansion valve 4a is located on the downstream side of the capillary tube 4b, and the low-stage compressor section 1 depends on the opening degree of the electric expansion valve 4a.
It is possible to control the refrigerant state (superheat degree) of the suction of a.

Next, the cooling operation will be described. During the cooling operation (or during the defrosting operation), the opening / closing device control means 9 closes the electromagnetic opening / closing valve 8.

During cooling operation, the four-way valve 2 for switching between heating and cooling
As a result, the flow of the refrigerant changes to the direction of the solid 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 outdoor heat exchanger 3 to be liquefied, and is depressurized to an intermediate pressure by the electric expansion valve 4a, so that the gas-liquid separator is formed. 5
However, since the electromagnetic on-off valve 8 is closed, the refrigerant is further decompressed to a lower pressure in the capillary tube 4b,
It is gasified in the indoor heat exchanger 6, and returns to the refrigerant compression device 1 through the four-way valve 2 for switching between heating and cooling.

Here, when the electromagnetic opening / closing valve 8 is open, the refrigerant circulation amount of the bypass circuit 7 changes even if the opening degree of the electric expansion valve 4a is changed, so that the superheat degree of the suction of the low-stage compressor section 1a is controlled. Although it is difficult to do so, by closing the electromagnetic opening / closing valve 8, it is possible to control the refrigerant state (superheat degree) of the suction of the low-stage compressor section 1a by the opening degree of the electric expansion valve 4a.

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. Further, in the above embodiment, the electromagnetic on-off valve is used as the opening / closing device, but other opening / closing devices may be used.

[0020]

The two-stage compression type refrigeration cycle apparatus of the present invention is controlled by keeping the switchgear closed by the switchgear control means during the cooling operation or the defrosting operation.
The individual expansion valve can control the refrigerant state of the suction of the refrigerant compression device, that is, the degree of superheat, which simplifies the control and reduces the cost.

[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 part 1b High-stage compressor part 2 Cooling / heating switching four-way valve (flow path switching valve) 3 Outdoor heat exchanger 4a Expansion valve (pressure reducing device) 4b Capillary tube 5 Gas-liquid separator 6 Indoor heat exchanger 7 Bypass circuit 8 Electromagnetic on-off valve (switching device) 9 Switching device control means

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 decompression device, a gas-liquid separator, a capillary tube and an indoor heat exchanger are connected, and a bypass circuit is provided that connects the gas outlet of the gas-liquid separator and the suction side of the high-stage compressor section.
A two-stage compression type refrigeration cycle apparatus characterized by comprising a switchgear in the bypass circuit to form a refrigeration cycle, and having switchgear control means for closing the switchgear during cooling operation and opening it during heating operation. ..