JPH0137185Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a refrigeration system, and more particularly, to a refrigeration system that uses a plurality of compressors and controls capacity by turning on and off the compressors.

Conventionally, a refrigeration system using a plurality of compressors connected in series and controlling the capacity by stopping the operation of one of the compressors is disclosed, for example, in Japanese Patent Publication No. 52-36629. As it is known.

This refrigeration system includes a first compressor 41 and a second compressor 42 as shown in FIG.
The second compressors 41 and 42 are connected in series to the suction pipe 43 of the refrigeration system, and an oil equalizing pipe 44 is provided between the shells of each of the compressors 41 and 42.

In addition, in Fig. 3, 45 is the suction side connecting pipe;
6 and 47 are conduits extending from the high pressure chambers of the respective compressors 41 and 42, and 48 is a discharge pipe.

By the way, in this conventional device, when controlling the capacity of the refrigeration system by, for example, stopping the operation of the first compressor 41 located on the upstream side and operating the second compressor 42 located on the downstream side, each compression The high pressure chambers of the compressors 41 and 42 are connected to the discharge pipe 48 via conduits 46 and 47, so the high pressure chamber of the first compressor 41 on the stop side has the high pressure discharged from the second compressor 42. The gas refrigerant flows in and becomes stagnant, resulting in
The refrigerant remaining in the high pressure chamber of the first compressor 41 and further in the discharge passage condenses, thereby closing the refrigerant gas passage. Therefore, when starting the compressor 41, the refrigerant gas compressed in the cylinder becomes difficult to discharge, and the cylinder internal pressure and discharge chamber internal pressure rise abnormally, causing damage to the suction valve, discharge valve, and discharge chamber. There is.

Therefore, in order to solve this problem, as shown in FIG. 4, the first compressor 41 and the second compressor are
A compressor 42 is connected in series via a low pressure side communication pipe 45, and an oil equalizing pipe 44 is provided between each shell of the compressors 41, 42, in which the high pressure chambers 41a, A high pressure side communication pipe 50 is provided between the high pressure chambers 41a and 42a to connect the high pressure chambers 41a and 42a, and the high pressure chambers 41a and 42 of the compressor 41 or 42 whose operation is stopped for capacity control are provided between the high pressure chambers 41a and 42a.
2a, the compressor 42 or 41 continues to operate.
We proposed and filed an application for a system in which high-pressure gas refrigerant discharged from
issue).

However, according to the earlier application, the problem of liquid compression can be solved, but each compressor 41,
42, in addition to connecting pipes 45 and 50 to the low pressure side and the high pressure side, an oil equalizing pipe 44 must also be installed, which increases the number of pipes accordingly.
There is a problem of high cost, and in addition, especially when only the second compressor 42 on the downstream side is operated, the low pressure side connecting pipe 45 is separate from the oil equalizing pipe 44 and is far above the oil level. Furthermore, the high-temperature high-pressure gas refrigerant discharged from the second compressor 42 is passed through the high-pressure side communication pipe 50 to the high-pressure chamber 41a of the first compressor 41 on the stop side. The oil temperature in the second compressor 42 is heated through the communication pipe 50, and the oil in the first compressor 41 is cooled by the low pressure gas refrigerant sucked through the low pressure side communication pipe 45. Although it is rarely heated, it is heated by the high pressure gas refrigerant flowing through the communication pipe 50, and as a result, the oil temperature of the second compressor 42 increases abnormally.
At the same time as the efficiency decreases, the temperature of the bearing section increases, reducing its reliability.

The purpose of the present invention is to provide a high-pressure side communication pipe so that even when one compressor is stopped, the discharged gas refrigerant flows into the high-pressure chamber of the stopped compressor, thereby eliminating liquid accumulation, and eliminating liquid accumulation when the compressor is restarted. While solving problems caused by compression, the piping configuration is simplified by making it possible for the low pressure side connecting pipe to also serve as an oil equalizing pipe, and at the same time connecting the low pressure side connecting pipe that also serves as the oil equalizing pipe to each low pressure chamber in each compressor. By carefully arranging the position, it is possible to minimize the contact of the low-pressure gas refrigerant flowing through the connecting pipe with the oil, thereby minimizing the mixing of the low-pressure gas refrigerant into the oil. This allows the oil to be reliably cooled even during operation, and solves problems caused by rising oil temperatures.

Therefore, the configuration of the present invention is a refrigeration system that is equipped with a plurality of compressors and whose capacity is controlled by turning on and off the compressors. A high-pressure side connecting pipe is provided to flow the high-pressure gas refrigerant discharged from the compressor that continues to operate, into the high-pressure chamber of the compressor that is stopped for capacity control, and a suction pipe is provided to the upstream compressor. In addition, at the lower part of the low pressure chamber in each of the compressors, it is possible to equalize the oil at a position slightly above the appropriate oil level height in each of these compressors, at the oil level height that rises when the upstream compressor is stopped. By providing a low-pressure connecting pipe at the position where the low-pressure gas refrigerant sucked from the suction pipe flows to the low-pressure chamber of the downstream compressor, a liquid accumulation occurs in the high-pressure chamber of the compressor that is stopped for capacity control. This makes it possible to equalize the oil in the low-pressure connecting pipe, simplify the piping structure, and prevent the oil temperature from rising abnormally when only the downstream compressor is operated.

Next, an embodiment of the refrigeration system of the present invention will be described based on the drawings.

The one shown in FIG. 1 is equipped with two compressors 1 and 2, and these compressors 1 and 2 are connected in series as described later, and a condenser 5 and an expansion valve are connected through a suction pipe 3 and a discharge pipe 4. 6 and an evaporator 7 are connected.

The compressors 1 and 2 are both closed shell compressors equipped with a motor M, and the suction pipe 3 is connected to the inside of the shell of the first compressor 1, that is, the low pressure chamber 11. , 2 low pressure chamber 11,
21 are connected in series by a low pressure side connecting pipe 10, and this connecting pipe 10 is connected to the low pressure chamber 1.
1 and 21 and at a position slightly above the appropriate oil level height H in each of the compressors 1 and 2,
The connecting pipe 10 can also be used as an oil equalizing pipe.

That is, when the second compressor 2 is operating, the low pressure gas refrigerant sucked into the low pressure chamber 11 of the first compressor 1 from the suction pipe 3 passes through the communication pipe 10 and flows into the low pressure chamber 22 of the second compressor 2. and the first compressor 1
The lubricating oil stored in the second compressor 2 also flows to the second compressor 2 side as the oil level rises and is evenly oiled.

Note that the appropriate oil level height H described above is the minimum oil level height required when the first compressor 1 is operating.

On the other hand, conduits 13 and 23 extending to the outside of the shell are connected to each high pressure chamber 12 and 22 in each of the compressors 1 and 2.
are connected to the discharge pipe 4, and between the high pressure chambers 12, 22, these high pressure chambers 12,
A high-pressure side communication pipe 9 is provided which communicates the compressor 1 or 2 with the discharge pipe 4 through the conduit 13 or 23 when the operation is stopped for capacity control, and when stopped. In the hyperbaric chamber 12 or 22,
The high pressure gas refrigerant discharged from the compressor 2 or 1 which continues to operate is made to flow through the high pressure side communication pipe 9.

Therefore, in the above configuration, when the first compressor 1 is stopped and only the second compressor 2 is operated to perform capacity control, the suction pipe 3 is connected to the first compressor 1.
The low-pressure gas refrigerant sucked into the low-pressure chamber 11 passes around the high-pressure chamber 12 in the stopped first compressor 1, contacts the oil surface, passes through the low-pressure side communication pipe 10, and is transferred to the second compressor. It flows into the low pressure chamber 21 of the compressor 2, and also flows into the high pressure chamber 1 of the first compressor 1.
A part of the high pressure gas refrigerant discharged from the second compressor 2 flows into the second compressor 2 via the high pressure side communication pipe 9,
The refrigerant flows through the high-pressure chamber 12 without stagnation, and flows through the conduit 13 to the discharge pipe 4 so as to join with the remainder of the high-pressure gas refrigerant that has passed through the conduit 23.

In this way, in the high pressure chamber 12 and conduit 13 of the first compressor 1 that is stopped, the high pressure gas refrigerant is maintained in a state where the refrigerant is constantly flowing without stagnation, and condensation due to stagnation of the refrigerant is reliably prevented. This can prevent accidents in which the suction valve, discharge valve, and discharge chamber are damaged due to abnormally high cylinder internal pressure and discharge chamber internal pressure when the first compressor 1 is started.

Moreover, due to the flow of high-pressure gas refrigerant into the high-pressure chamber 12 of the first compressor 1, the oil temperature in the first compressor 1 tends to rise abnormally. The second compressor 2 is cooled by the low pressure gas refrigerant flowing into the second compressor 2.
This will definitely solve the problem of the oil temperature in the compressor 2 rising abnormally.

Also, contrary to the case of capacity control explained above,
Even when the second compressor 2 is stopped and only the first compressor 1 is operated to perform capacity control, basically, in the high pressure chamber 22 of the stopped second compressor 2, A part of the high-pressure gas refrigerant discharged by the first compressor 1 during operation is maintained in a circulating state, and the second
This makes it possible to eliminate accidents in which the suction valve, discharge valve, and discharge chamber are damaged when the compressor 2 is started.

In the embodiment described above, as shown in FIG.
The oil heating parts 91, 91 may be formed by immersing them in the lubricating oil of each compressor 1, 2 and forming them into a loop shape as appropriate.

By doing so, for example, when the capacity is controlled such that the first compressor 1 is stopped and only the second compressor 2 is operated, abnormal cooling of the lubricating oil due to the low pressure gas refrigerant flowing through the first compressor 1 can be prevented. can be prevented. That is, the lubricating oil temperature can be maintained at an appropriate temperature by the heating action of the oil heating section 91, and the oil temperature will abnormally drop due to excessive cooling due to the flow of the low-pressure gas refrigerant, and the low-pressure gas refrigerant will dissolve into the lubricating oil. can be prevented from being diluted.

As described above, oil heating by the oil heating section 91 can also be performed by the high pressure chambers 12 and 22, so it is not necessarily necessary to provide them.

As described above, in the present invention, between the high pressure chambers 12 and 22 of the first and second compressors 1 and 2,
The compressor 1 or 2 is provided with a communication pipe 9 that communicates the compressors 2 and 22 with each other, and the operation of the compressor 1 or 2 is stopped for capacity control.
Since the high pressure gas refrigerant discharged from the compressor 1 or 2 that continues to operate is made to flow through the high pressure chamber 12 or 22 of the Condensation due to stagnation can be prevented, and when the stopped compressor 1 or 2 is restarted, the condensed liquid refrigerant will not close the passage and the cylinder internal pressure and discharge chamber internal pressure will abnormally rise, causing the suction valve to close. , the problem of damage to the discharge valve and discharge chamber can be reliably solved.

Moreover, in the present invention, the low pressure side connecting pipe 10 connecting the low pressure chambers 11 and 21 of each of the compressors 1 and 2 is provided at the lower part of the low pressure chambers 11 and 21 of each of the compressors 1 and 2. It was installed at a position slightly above the appropriate oil level height in compressors 1 and 2, and at a position where the oil level can be equalized by the oil level that rises when upstream compressor 1 is stopped, so when compressors 1 and 2 are operating simultaneously, , the oil level height in the low pressure chambers 11, 21 of each compressor 1, 2 is:
It is located below the communication pipe 10, and therefore, oil does not enter into the communication pipe 10, and only low-pressure gas refrigerant flows into the low-pressure side communication pipe 10. Therefore, the low pressure gas refrigerant does not dissolve into the oil in the low pressure side communication pipe 10, and when the upstream side compressor 1 is stopped and only the downstream side compressor 2 is operated to control the capacity. Since oil is equalized by the low pressure side connecting pipe 10 only when the oil level in the stopped compressor 1 rises, the connecting pipe 1 is
Therefore, even during oil equalization, the low-pressure gas refrigerant flowing through the low-pressure side connecting pipe 10 is prevented from dissolving into the oil as much as possible in the low-pressure side connecting pipe 10. While having the above-mentioned advantages, by using the low-pressure side communication pipe 10 also as an oil-equalizing pipe, the oil-equalizing pipe can be omitted, and the piping structure can be simplified accordingly, and the downstream secondary When controlling the capacity by operating only the compressor 2, even if the oil temperature in the stopped first compressor 1 is heated by the high pressure gas refrigerant flowing from the high pressure chamber 22 of the second compressor 2, the low pressure side Since it is cooled by the low pressure gas refrigerant flowing through the communication pipe 10, the oil temperature in the second compressor 2 does not rise abnormally and can be maintained at an appropriate temperature.
This makes it possible to eliminate problems such as a decrease in the operating efficiency of the second compressor 2 and a decrease in the reliability of the bearing section.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing one embodiment of the device of the present invention, Fig. 2 is a schematic sectional view of only the compressor showing another embodiment, Fig. 3 is a conventional example, and Fig. 4 is a previously applied It is an explanatory diagram showing an improvement plan. 1...First compressor, 2...Second compressor, 3...
Suction pipe, 4...Discharge pipe, 11, 21...Low pressure chamber,
12, 22...High pressure chamber, 9...High pressure side communication pipe, 1
0...Low pressure side communication pipe.

Claims (1)

[Scope of utility model registration request] A plurality of compressors 1 and 2 are provided, and these compressors 1,
2, the high pressure chamber 1 of each of the compressors 1 and 2 is
Between 2 and 22, these high pressure chambers 12 and 22 are communicated with each other, and the high pressure chamber 12 or 22 of the compressor 1 or 2 that is stopped for capacity control is connected to the high pressure chamber 12 or 22 of the compressor 1 or 2 that continues to operate. A high-pressure communication pipe 9 is provided through which the discharged high-pressure gas refrigerant flows, and a suction pipe 3 is connected to the upstream compressor 1. The suction pipe 3 is located at a position slightly above the appropriate oil level height in each compressor 1, 2, and at a position where oil can be equalized at the oil level height that rises when the upstream compressor 1 is stopped.
A refrigeration system characterized by being provided with a low-pressure side communication pipe 10 that allows a low-pressure gas refrigerant sucked from the downstream compressor 2 to flow into a low-pressure chamber 21 of a downstream compressor 2.