JPH0623623B2 - Oil level control device for multi refrigerator - Google Patents

Description

Description: (a) Field of Industrial Application The present invention relates to an improvement in an oil level control device for a multi-refrigerator, and more particularly to a plurality of compressors having different internal pressures of respective crank chambers, that is, suction pressures. The present invention relates to a multi-refrigerator such as a subcooler system, a satellite system, and a two-stage compressor equipped with the.

(B) Conventional technology Conventionally, a multi-refrigerator provided with a plurality of compressors having different crank chamber internal pressures has been proposed in JP-A-55-46315 and configured as a refrigerant circuit as shown in FIG. ing.

Explaining below, (1) is an auxiliary compressor in which the internal pressure of the crank chamber (1a), that is, the suction pressure is high, and (2) and (3) are the internal pressures of the respective crank chambers (2a) and (3a). Lower main compressor, (4) oil separator, (5) condenser, (6) liquid receiver, (7) subcooler, (8) main expansion valve, (9) evaporator These are sequentially connected by piping to form a main refrigerant circuit. And the auxiliary compressor (1) and the main compressor
(2) The refrigerant gas discharged from (3) is introduced into the oil separator (4) through a common discharge pipe (10) having a check valve (21). The refrigerant gas separated from the oil by the oil separator is condensed by the condenser (5) and then introduced into the liquid receiver (6) to be stored as a liquid refrigerant. This liquid refrigerant then passes through the inside of the subcooler (7), where a part of the liquid refrigerant derived from the liquid receiver (6) is branched from the middle by the branch pipe (11), and the subcooler liquid solenoid valve (22) Passes through the auxiliary expansion valve
After being decompressed by (12), it flows in the subcooler (7) while exchanging heat with the liquid refrigerant in the main refrigerant circuit. As a result, the liquid refrigerant in the main refrigerant circuit is supercooled by a part of the liquid refrigerant branched from the middle. Further, the liquid refrigerant branched from the middle is evaporated in the subcooler (7), then derived from the subcooler, and returned to the auxiliary compressor (1). On the other hand, the liquid refrigerant in the main refrigerant circuit that is supercooled in the subcooler (7) is introduced into the main expansion valve (8) and the evaporator (9) and evaporated, and then the respective main compressors (2) (3) Have been returned to.

In the multi-refrigerator constructed as described above, the oil level control device thereof is constructed as disclosed in Japanese Patent Publication No. 55-21945 and shown in FIG. Explaining below, the auxiliary compressor (1) and the main compressor (2) (3) are discharged together with the refrigerant gas and separated and stored in the oil separator (4) through the common discharge pipe (10). Oil
(13) is supplied to the oil tank (15) through the oil return pipe (14). This is because the pressure in the oil tank (15) is maintained at a low pressure by the pressure equalizing pipe (16) connecting the oil tank and the suction side of the auxiliary pressure machine (1), and the oil separator (4 This is because the oil (13) is pumped by the pressure difference between the oil tank (15) and the oil tank (15). The oil (13) stored in this oil tank (15) is the oil return pipe.
It is supplied to the auxiliary compressor (1) and the main compressors (2) and (3) via (17) and the oil regulators (18), (19) and (20). This is an auxiliary compressor with a high suction pressure for the pressure in the oil tank (15).
By setting the pressure to approximately the same as that of the crank chamber (1a) of (1) and by providing a drop between the oil tank and each of the compressors (1), (2) and (3), each oil from the oil tank is The oil (13) is supplied to the regulators (18), (19) and (20) and the oil levels of the compressors (1), (2) and (3) are made uniform by the oil leveling action of the oil regulators.

However, the oil level control device for a multi-refrigerator thus configured sets the pressure in the oil tank (15) to substantially the same pressure as the auxiliary compressor (1) having a high suction pressure.
Therefore, the supply pressure of the oil (13) applied to the oil regulator (19) (20) from the oil tank via the oil return pipe (17) is likely to become excessively large, and in particular, the oil regulator (19) (20) Opens the valve beyond its capacity and unnecessarily feeds oil (13) to the main compressor (2) (3) with a low suction pressure. This disturbs the oil leveling function of the oil regulators (19) (20), and the auxiliary compressor (1) and the main compressor (2) (3)
Make the oil level uneven between the main compressor (2)
This causes various problems such as the increase in the oil discharge amount of (3), and the oil level control device lacks reliability. This problem is caused by the auxiliary compressor with high suction pressure.
Oil tank (15) and main compressor when (1) is stopped
(2) It becomes particularly remarkable because the differential pressure between (3) is further increased.

(C) Object of the Invention The present invention has been made in view of the above point, and an object thereof is to provide an oil level of a multi-refrigerator including a plurality of compressors having different internal pressures of crank chambers. In the control device, the oil supply pressure applied to the oil regulator mounted on the main compressor having a low suction pressure from the oil tank is prevented from being excessively increased, and the oil regulator's equalizing action is favorably maintained and the oil level is maintained. It is to improve the reliability of the control device.

(D) Configuration of the invention The present invention is a multi-refrigerator including a main compressor that sucks intake gas through a crank chamber and an auxiliary compressor that also sucks intake gas. The lower side of the main compressor is used as a main compressor, and a common discharge pipe that guides the refrigerant discharged from each of these compressors, an oil separator connected to this discharge pipe, and the oil of this oil separator are returned to the oil tank. Oil return pipe, a second oil return pipe for returning the oil in the oil tank to an oil regulator formed in the main compressor and the auxiliary compressor, and an equalizer communicating the oil tank and the suction side of the auxiliary compressor. Second composed of a pressure tube and connected to the main compressor
The oil return pipe is equipped with a differential pressure valve, and the pressure equalizing pipe and the suction side of the main compressor are connected by a bypass pipe with a solenoid valve, and the oil stored in the oil tank has the same pressure as that of the tank. Second oil return pipe to the auxiliary compressor, which is
While being supplied at its supply pressure and head through the oil regulator, part of the oil that has flowed through this second oil return pipe and reached the differential pressure valve becomes the internal pressure of the main compressor due to the operation of the differential pressure valve. After flowing through the second oil return pipe having an appropriate oil supply pressure, the oil is supplied at the supply pressure and the head to the main compressor via the oil regulator.

(E) Embodiment An embodiment of the present invention will be described below with reference to FIG. 2. Since the basic structure of the refrigerant circuit and its operation are the same as those of the conventional example shown in FIG. Description will be omitted, and only the points of this embodiment different from the conventional example, that is, the oil level control device will be described.

(1) is an auxiliary compressor on the side where the internal pressure of the crank chamber (1a), that is, the suction pressure is high. (2) and (3) are the respective crank chambers (2
a) The main compressor on the side with low internal pressure in (3a). (14) is a common refrigerant discharge pipe from the auxiliary compressor (1) and the main compressor (2) (3)
It is a first oil return pipe for supplying the oil (13) stored in the oil separator (4) after being discharged through (10) to the oil tank (15). This is a pressure equalizing pipe that connects the oil tank (15) and the refrigerant suction pipe (23) of the auxiliary compressor (1).
Since the oil tank is maintained at a low pressure by (24), the pressure difference causes the oil (1) in the oil separator (4) to
This is because 3) is pumped to the oil tank (15). (25) is the oil regulator (18) (1) that is equipped with the oil (13) in the oil tank (15) installed in the auxiliary compressor (1) and the main compressor (2) (3).
2nd feeding to each compressor (1) (2) (3) via 9) (20)
Oil return pipe. (26) is the second oil return pipe (25)
The differential pressure valve is provided between the auxiliary compressor (1) and the main compressors (2) and (3). This differential pressure valve (26) consists of the valve and the main compressor (2) (3)
The pressure in the crank chambers (2a) (3a) of the main compressors (2) (3) transmitted by the pipe (28) communicating with the refrigerant suction pipe (27) of the second oil from the oil tank (15) It detects the pressure difference with the oil supply pressure transmitted through the return pipe (25) and adjusts its opening.When this pressure difference is large, the opening is throttled to reduce the oil regulator (19) (20 ), The oil supply pressure applied to the second oil return pipe (25), the oil supply (13) in the oil tank (15) is fully opened when the pressure difference is small Regulator (19) (20)
It is to be supplied to the main compressors (2) and (3) via.

The oil (13) in the oil tank (15) is first supplied to the auxiliary compressor (1) via the second oil return pipe (25) and the oil regulator (18). As described above, the internal pressure of the oil tank (15) is set to the same pressure as the crank chamber (1a) of the auxiliary compressor (1), and the oil tank (15) is located above the auxiliary compressor (1). This is because the oil (13) can be supplied from the tank to the auxiliary compressor (1) by the supply pressure and the head of the tank. (29)
Is a bypass pipe branched from the middle of the pressure equalizing pipe (24) and connected to the refrigerant suction pipe (27) of the main compressors (2) and (3) having a low suction pressure. Reference numeral (30) is a solenoid valve provided in the bypass pipe (29). This solenoid valve (30) is an auxiliary compressor with high suction pressure.
It is set to open only when (1) stops. This is because when the auxiliary compressor (1) is stopped and the internal pressure of the compressor rises, the internal pressure of the oil tank (15) also rises due to the pressure equalizing pipe (24), and the second oil return pipe from the oil tank (15).
The oil supply pressure transmitted to each oil regulator (19) (20) via (25) becomes excessively high and the oil regulator
(18) (19) (20) This is to solve the problem of disturbing the pressure equalizing action, and when the auxiliary compressor (1) stops, the solenoid valve (30) is opened and the pressure equalizing pipe (24 ) To the refrigerant suction pipe (27) so that the main compressor is installed in the oil tank (15).
(2) The low pressure is applied to (3) to keep the internal pressure of the tank lower, and the oil (13) in the oil tank (15) is connected to the second oil return pipe (25) and the differential pressure valve (26). , Oil regulator (1
8), (19), and (20), so that the supply pressure and head allow good supply to the respective compressors (1), (2), and (3). At this time, the differential pressure valve (26) is the second oil return pipe (25).
Since the differential pressure between the pipe and the pipe (28) almost disappears, it is fully opened, and the oil supply performed via the second oil return pipe (25) is not disturbed.

(F) Effects of the Invention As described above, according to the present invention, in the multi-refrigerator including the main compressor that sucks the intake gas through the crank chamber and the auxiliary compressor that also sucks the intake gas, the high suction pressure side Is the auxiliary compressor and the main compressor is on the low suction pressure side, and a common discharge pipe for guiding the refrigerant discharged from each of these compressors, an oil separator connected to this discharge pipe, and the oil of this oil separator. Of the oil tank to the oil tank, a second oil return pipe for returning the oil of the oil tank to an oil regulator formed in the main compressor and the auxiliary compressor, and a second oil return pipe of the oil tank and the auxiliary compressor. A pressure equalizing pipe communicating with the suction side is provided, and a differential pressure valve is provided in the second oil return pipe connected to the main compressor.
Further, since the pressure equalizing pipe and the suction side of the main compressor are connected by a bypass pipe with a solenoid valve, the oil stored in the oil tank is stored in the tank via a second oil return pipe and an oil regulator. While being supplied to the auxiliary compressor having the same pressure as that of the auxiliary compressor at its supply pressure and head, a part of the oil flowing through the second oil return pipe and reaching the differential pressure valve is actuated by the differential pressure valve to operate the main compressor. After the oil supply pressure becomes equal to the internal pressure of the oil and flows through the second oil return pipe, it can be supplied to the main compressor through the oil regulator at the supply pressure and the head. This prevents the supply pressure of the oil applied to the main compressor from the oil tank through the second oil return pipe from becoming excessively large as in the conventional case, and maintains the oil leveling effect of the oil regulator well, It improves the reliability of the oil level control device.

Even when the auxiliary compressor with high suction pressure is stopped, the solenoid valve of the bypass pipe that is branched from the middle of the pressure equalizing pipe is opened, so that the internal pressure of the oil tank does not rise unlike the conventional case. It is possible to prevent the oil supply pressure transmitted through the second oil return pipe from becoming excessively large.

[Brief description of drawings]

FIG. 1 is a circuit diagram of refrigerant and oil of a multi-refrigerator showing a conventional example, and FIG. 2 is a circuit diagram of refrigerant and oil of a multi-refrigerator showing an embodiment of the present invention. (1) …… Auxiliary compressor, (2) (3) …… Main compressor, (4) …… Oil separator, (14) …… First oil return pipe, (15) ……
Oil tank, (18) (19) (20) …… Oil regulator,
(24) …… equalizing pipe, (25) …… second oil return pipe, (26)…
… Differential pressure valve, (29) …… Bypass pipe, (30) …… Solenoid valve.

Claims (1)

[Claims] 1. In a multi-refrigerator including a main compressor that sucks intake gas through a crank chamber and an auxiliary compressor that also sucks intake gas, a side having a high suction pressure is placed on a side having a high suction pressure and a side having a low suction pressure. A common discharge pipe that serves as a main compressor and guides the refrigerant discharged from each of these compressors, an oil separator connected to this discharge pipe, and a first oil return pipe that returns the oil of this oil separator to an oil tank. And a second oil return pipe for returning the oil in the oil tank to an oil regulator formed in the main compressor and the auxiliary compressor, and a pressure equalizing pipe communicating the oil tank and the suction side of the auxiliary compressor. However, a differential pressure valve is provided on the second oil return pipe connected to the main compressor, and the pressure equalizing pipe and the suction side of the main compressor are connected by a bypass pipe with a solenoid valve. Oil level control apparatus for a multi refrigerator according to claim.