JPH0784955B2 - Screw refrigerator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refrigerator including a screw compressor.

(Prior Art) Conventionally, it is disclosed in Japanese Utility Model Publication No. Sho 55-34538 and the fourth
As shown in the figure, a condenser (B), an expansion mechanism (C), an evaporator (D) and an accumulator (E) are sequentially connected to the discharge side of the compressor (A), and the condenser (B) is also connected. And a expansion mechanism (C) are connected to a high-pressure liquid pipe (HL), and a receiver (F) for accumulating a high-pressure liquid refrigerant is interposed between the inlet and the outlet of the receiver (F). While connecting the first and second on-off valves (V1) (V2), a connecting pipe (G) is connected between the gas region of the liquid receiver (F) and the accumulator (E), A third opening / closing valve (V3) is interposed in the connecting pipe (G). Thus, when performing the pump down operation for collecting the refrigerant in the liquid receiver (F) at the time of maintenance and inspection, the first opening / closing valve (V1)
Open and the second on-off valve (V2) is closed to continue the operation, and the liquid is sequentially stored from the condenser (B) to the liquid receiver (F), and the third on-off valve (V3) is also stored. Is opened to lower the internal pressure of the liquid receiver (F) so that the liquid flow from the condenser (B) to the liquid receiver (F) can be promoted.

In this type of refrigerator, a high pressure gas pipe (HG) connecting a compressor (AA) and a condenser (BB) is disclosed in Japanese Utility Model Publication No. 50-120008 and as shown in FIG. Oil recovery device (Q) is installed in the oil recovery pipe (K), an oil pump (P) and an oil cooling pipe (U) are installed in the oil return pipe (K), and the oil recovery pipe (Q) is used for recovery. In the oil cooler (U), a high-pressure liquid pipe (HL) that connects the condenser (BB) and the expansion mechanism (CC)
And the intermediate port (M) of the compressor (AA), which is cooled by the evaporating action of the refrigerant flowing through the cooling pipe (T) having the decompression mechanism (X) interposed in the middle of the compressor (AA). I am trying to return to AA).

(Problems to be Solved by the Invention) By the way, according to the configuration of FIG. 4, the third on-off valve (V
By opening 3), the internal pressure of the receiver (F) can be lowered, so that even during normal refrigeration operation,
If the third on-off valve (V3) is opened to perform the operation, the liquid flow to the liquid receiver (F) can be promoted, the retention of the liquid refrigerant in the condenser (B) can be suppressed, and the refrigerating capacity can be improved. It is expected to be able to exhibit well. However, in this case, the high-pressure and high-temperature gas in the liquid receiver (F) escapes to the suction side of the compressor (A) through the connection pipe (G) and the accumulator (E). The temperature of the gas sucked into the compressor (A) and the pressure of the gas are increased, which hinders the amount of sucked air and adversely reduces the capacity.

Therefore, next, consider the case where the connecting pipe (G) is connected to the intermediate port of the compressor (A) where the compression operation proceeds to some intermediate pressure and intermediate temperature rather than the suction side at low pressure and low temperature. To In this case, since heating and pressurization of the intake gas can be suppressed, the above-mentioned obstruction of the intake air volume can be suppressed, but as shown in FIG. 5, in a normal system, an oil recovery unit (HG) is installed in the high pressure gas pipe (HG). Q), and the refrigerant outlet from the oil cooler (U), that is, the outlet of the cooling pipe (T) is connected to the intermediate port (M), so that it is connected from the liquid receiver (F). The refrigerant introduced through the pipe (G) and the refrigerant from the oil cooler (U) join at the intermediate port (M), which causes a new problem. That is, the pressure of the intermediate port (M) is increased by the refrigerant introduced from the high-pressure side receiver (F), and the evaporation temperature of the refrigerant flowing through the cooling pipe (T) connected to the intermediate port (M). Is raised and the oil cooling efficiency deteriorates,
The refrigerant flow rate introduced from the liquid receiver (F) to the intermediate port (M) is the introduction flow rate from the cooling pipe (T), that is, the oil cooling pipe (U).
There was a problem that the internal pressure of the liquid receiving pipe (F), that is, the reduced pressure value thereof, fluctuated due to the influence of the oil cooling load.

In the present invention, attention is paid to the structure of a single screw compressor including one screw rotor and a pair of gate rotors, and two systems of compression chambers are formed. By devising the connection structure of the refrigerant from the condenser, it is possible to promote the liquid flow from the condenser to the receiver without impairing the function of the oil cooler, and while suppressing the reduction of the intake air volume during normal operation. An object is to provide a refrigerating device.

(Means for Solving the Problem) Therefore, in the present invention, a single screw rotor (SR) and a pair of gate rotors (GR, GR) are provided, and two systems of the first and second compression chambers (10, 20) are provided. The single screw compressor (1) having the above structure is used, and the compressor (1) is sequentially connected to the condenser (2), the expansion mechanism (3) and the evaporator (4), and the condenser (2) is also connected. The liquid receiver (9) is installed in the high pressure liquid pipe (23) connecting the expansion mechanism (3) with the high pressure gas pipe (12) connecting the compressor (1) and the condenser (2). In the configuration in which the oil recovery device (6) is interposed and the return oil from the oil recovery device (6) is cooled by the refrigerant via the oil cooler (7), the liquid receiver (9) The gas range of
It is connected to a first intermediate port (1c) located in the middle of the suction port (1a) and the discharge port (1b) in the first compression chamber (10) through the first connection pipe (31), and The refrigerant outlet of the oil cooler (7) is located in the middle of the suction port (2a) and the discharge port (2b) in the second compression chamber (20) via the second connecting pipe (32). 2 I decided to connect to the intermediate port (2c).

(Operation) Since the gas in the liquid receiver (9) is released to the intermediate port (1c) in the first compression chamber (10), which is at intermediate pressure during compression, through the first connecting pipe (31). , Suction port (1
It is possible to reduce adverse effects on the inhaled gas inhaled in a) and suppress the obstruction of the inhaled air volume. Moreover, since the gas region of the liquid receiver (9) is connected to the intermediate port (1c), the internal pressure of the liquid receiver (9) is lower than that of the condenser (2) which is high pressure. The pressure can be maintained so that the liquid can be well flowed from the condenser (2) to the liquid receiver (9).

In this case, the gas region of the liquid receiver (9) is the first connecting pipe (3
The outlet refrigerant from the oil cooler (7) is introduced via the first compression chamber (10) on one side of the two systems of compression chambers, that is, the second connection pipe (32) via the first connection. Since it is connected to a chamber separated from the second compression chamber (20), the refrigerant introduced from the liquid receiver (9) does not raise the evaporation temperature on the oil cooler (7) side, and vice versa. It is possible to eliminate the adverse effect that the internal pressure of the liquid receiver (9) fluctuates due to the amount of refrigerant introduced from the oil cooler (7) due to fluctuations in the oil cooling load in the oil cooler (7).

(Embodiment) The refrigerator shown in FIG. 1 has, on the discharge side of a single screw compressor (1), a condenser (2) that condenses the discharged high pressure gas refrigerant into a high pressure liquid refrigerant, and the high pressure. An expansion mechanism (3) for decompressing the liquid refrigerant into a low-pressure liquid refrigerant, an evaporator (4) for vaporizing the low-pressure liquid refrigerant into a low-pressure gas refrigerant, and an accumulator (5) for separating a liquid component from the low-pressure gas refrigerant. ) Are sequentially connected through a refrigerant pipe (50) to form a refrigeration cycle.

A high pressure liquid pipe (23) connecting the condenser (2) and the expansion mechanism (3) is provided with a liquid receiving pipe (9) for storing high pressure liquid refrigerant, and is condensed with the compressor (1). Oil connected to the oil supply port (60) of the compressor (1) from the oil recovery device (6) by interposing the oil recovery device (6) in the high pressure gas pipe (12) connecting to the device (2). The oil cooler (7) is connected to the return pipe (61).

The oil cooler (7) has a jacket (7) through which return oil flows.
1) and a refrigerant flow pipe (72) arranged therein, branching from the outlet side of the liquid receiver (6) in the high pressure liquid pipe (23), and controlling the opening and closing of the valve in the middle The oil in the jacket (71) is cooled by the refrigerant introduced into the refrigerant flow pipe (72) through the branch pipe (37) having the enabled pressure reducing mechanism (13).

As shown in FIGS. 2 and 3, the single screw compressor (1) includes a single screw rotor (SR) and a rotor (SR) inside a closed casing (100).
A pair of gate rotors (GR, GR) that mesh with each other, and two systems of first and second compression chambers (10) above and below the screw rotor (SR) with the gate rotor (GR.GR) as a boundary. (20) is formed, and in each compression chamber (10) (20), from each suction port (1a) (2a) to discharge port (1b)
The refrigerant is compressed toward (2b). Each suction port (1a) (2a) is connected to the low pressure gas pipe (51) extending from the accumulator (5), and each discharge port (1b) (2b) is connected to the high pressure gas pipe (12). As opposed to
Each is commonly connected.

With the above configuration, the upper gas region (9a) of the liquid receiver (9)
Is an intermediate port (1) located between the suction port (1a) and the discharge port (1b) in the first compression chamber (10).
c) via the first connecting pipe (31) and the outlet of the refrigerant flow pipe (72) in the oil cooler (7) via the second connecting pipe (32). 2 compression chambers (20)
Connected to a second intermediate port (2c) located intermediate between the suction port (2a) and the discharge port (2b).

In addition, even in the present embodiment, in order to perform the pump down operation as in the above-described conventional example, the first and second inlets and the outlets of the liquid receiver (9) in the high pressure liquid pipe (23) are respectively provided. Second
The opening / closing valves (8a) and (8b) are installed, and the third opening / closing valve (8c) is installed in the gas pipe (31).

Thus, during normal refrigeration operation, the third opening / closing valve (8c)
By opening the gas, the gas in the receiver (9) is released to the intermediate port (1c), which is at an intermediate pressure during compression, and thus adversely affects the intake fluid drawn into the intake port (1a). Although the pressure can be reduced, the internal pressure of the liquid receiver (9) can be maintained at a lower value than that of the condenser (2), and liquid can be favorably flowed from the condenser (2) to the liquid receiver (9). Of.

At this time, the first connection pipe (31) is connected to the first compression chamber (10) and extends from the oil cooler (7) to the second connection pipe (32).
Since it is separated from the second compression chamber (20) to which is connected, the intermediate pressure and temperature of the second intermediate port (2c) are increased by the refrigerant introduced from the first connection pipe (31). There is no. Therefore, the evaporation temperature in the refrigerant flow pipe (72) connected to the second intermediate port (2c) does not rise,
It is properly maintained, and the cooling effect in the oil cooler (7) can be exhibited well. Further, since the cooling effect can be improved, the heat transfer area of the refrigerant flow pipe (72) can be reduced.

On the other hand, even if the amount of refrigerant introduced from the second connection pipe (32) into the second compression chamber (20) may fluctuate due to the oil cooling load in the oil cooler (7), that is, for example, Even if the decompression mechanism (13) repeatedly opens and closes at intervals of 2 to 3 minutes to intermittently adjust the amount of the refrigerant introduced into the refrigerant flow pipe (72), the effect of the hunting does not occur. Since it does not reach the first compression chamber (10), the internal pressure of the liquid receiver (9) is kept constant without fluctuation, and the liquid flow from the condenser (2) can always be stably performed. Of.

(Effects of the Invention) As described above, in the present invention, the first and second compression chambers (10) of the two systems are provided.
(20) is formed in the single screw compressor (1), the liquid receiver (9) is interposed in the high-pressure liquid pipe (23), and the oil recovery device (in the high-pressure gas pipe (12) ( In the refrigerator in which the return oil from 6) is cooled by the refrigerant, the refrigerant from the liquid receiver (9) and the oil recovery device (6) is supplied to the first and second connecting pipes (31) (32), respectively. ) Through the first and second
Since it is individually connected to the compressor chambers (10) and (20), it does not impair the function of the oil cooler (7), and at the time of normal operation, it can receive from the condenser (2) while suppressing a decrease in the intake air volume. The liquid flow down to the liquid container (9) can be promoted and the refrigerating capacity can be exhibited well.

[Brief description of drawings]

FIG. 1 is a piping diagram of the refrigerator of the present invention, FIG. 2 is a schematic plan view showing the internal structure of a single screw compressor, FIG. 3 is a sectional view of the III-III principal part thereof, and FIGS. 4 and 5 are It is a piping diagram of a prior art example. (1) …… Screw compressor (SR) …… Screw rotor (GR) …… Gate rotor (10) …… First compression chamber (20) …… Second compression chamber (1a, 2a) …… Suction port ( 1b, 2b) …… Discharge port (1c) …… First intermediate port (2c) …… Second intermediate port (2) …… Condenser (3) …… Expansion mechanism (4) …… Evaporator (6) …… Oil collector (7) …… Oil cooler (9) …… Liquid receiver (12) …… High pressure gas pipe (23) …… High pressure liquid pipe (31) …… First connection pipe (32)… … Second connecting pipe

Claims (1)

[Claims] 1. A single screw compressor (1) having one screw rotor (SR) and a pair of gate rollers (GR, GR) and forming two systems of first and second compression chambers (10, 20). The high pressure connecting the compressor (1), the condenser (2), the expansion mechanism (3) and the evaporator (4) in sequence, and connecting the condenser (2) and the expansion mechanism (3). Liquid pipe (2
The liquid receiver (9) is installed in 3) while the compressor (1) is installed.
The oil recovery device (6) is installed in the high-pressure gas pipe (12) connecting the compressor and the condenser (2), and the return oil from this oil recovery device (6) is passed through the oil cooler (7) as a refrigerant. A screw refrigerator configured to be cooled by means of the first compression chamber (10) in the gas region of the liquid receiver (9) via a first connecting pipe (31).
Is connected to a first intermediate port (1c) located intermediate between the intake port (1a) and the discharge port (1b), and the refrigerant outlet portion of the oil cooler (7) is connected to the second connecting pipe (32). Through the suction port (2) in the second compression chamber (20).
A screw refrigerator characterized by being connected to a second intermediate port (2c) located intermediate between a) and the discharge port (2b).