JPH0480555A - Refrigerating plant - Google Patents

Abstract

PURPOSE:To keep a balance of oil between a plurality of compressors and to prevent the occurrence of oil shortage running by providing a plurality of individually operable compressors and locating a valve, closed during individual running of the compressor, in an oil uniformizing pipe through which a plurality of the compressors are interconnected. CONSTITUTION:When first and second compressors 1 and 2 are simultaneously run, first and second on-off valves 10 and 11 are opened, and only a third on-off valve 14 is closed. A refrigerant delivered from the two compressors 10 and 11 flows as shown by a solid line arrow mark. In which case, oil in a refrigerant delivered from the compressors 1 and 2 is stored in an oil separator 6. The refrigerant is recovered (as shown by a one-dot chain line arrow mark) in the compressors 1 and 2 through first and second branch pipes 8 and 9 through opening of the first and second on-off valves 10 and 11. Since, during simultaneous operation, the third on-off valve 14 is left in closed, even when a difference is produced between pressures in the compressors 1 and 2, there is no fear of oil flowing from the compressor the pressure of which is high to the compressor the pressure of which is low through an oil uniforming pipe 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a refrigeration system equipped with a plurality of individually operable compressors.

(b) Conventional technology This type of refrigeration equipment was first demonstrated in the 1960s.
There is a publication No. 2-40134.

This includes multiple compressors that can be operated individually, and the discharge pipes of each compressor are connected to form a common discharge pipe.
An oil separator is installed in this common discharge pipe to separate the lubricating oil (hereinafter referred to as 1 oil) in the refrigerant discharged from each compressor from this refrigerant, and send it to each compressor via an oil return pipe. It was designed to return to .

When the respective compressors are operated simultaneously, the oil levels within these compressors are kept approximately equal to prevent the respective compressors from running out of oil.

(8) Problem to be solved by the invention Here, in this refrigeration system, only one compressor is operated (
If individual operation is performed, the following problems may occur due to the above-mentioned oil equalizing pipe.

That is, the pressure inside the compressor during operation is lower than the pressure inside the compressor when it is stopped. Therefore, the oil in the stopped compressor is drawn into the operating compressor through the oil equalizing pipe, and the oil in the stopped compressor decreases. Therefore, if a stopped compressor is operated, oil may run out.

An object of the present invention is to maintain oil balance in a plurality of compressors that can be operated individually, thereby making oil-out operation less likely to occur.

(d) Means for Solving the Problems In order to achieve this object, the present invention is provided with a plurality of compressors that can be operated individually, and an oil equalizing pipe that connects these plurality of compressors is provided with a pipe that allows the compressors to be operated individually. The device is equipped with a valve that can be closed at certain times.

(*) When the compressors are operated individually, the valves of the oil equalization pipes that connect multiple compressors are closed, so that the oil from the stopped compressors is not drawn into the operating compressors through the oil equalization pipes. become.

(f) In the drawings, 1 is a first scroll compressor (hereinafter referred to as 1 the first compressor), and 2 is a second scroll compressor (hereinafter referred to as the ``second compressor''). , these measuring compressors are arranged in parallel. The discharge pipes 3.4 of these compressors 1 and 2 are connected to a common discharge pipe 5. 6 is an oil separator connected to this common discharge pipe, 7 is an oil return pipe extending from this oil separator, and its tip is connected to a first branch pipe 8 connected to the first compressor 1 and a second compressor. It is branched into a second branch pipe 9 that connects to the machine 2. 10 is a first on-off valve provided on the first branch pipe 8, and 11 is a second on-off valve provided on the second branch pipe. 13 is the first compressor 1
A third on-off valve (valve) 14 is provided in an oil equalizing pipe connecting the compressor 2 and the second compressor 2. The operations of these three on-off valves will be described later. 15 is a condenser, 16 is a blower for cooling the refrigerant in the condenser, 17 is a liquid receiver, 18 is an expansion valve, 19 is an evaporator, and 20 is a gas-liquid separator. These devices constitute a refrigeration system 21. ing. This evaporator 19 is housed in a freezer/refrigerator showcase in a convenience store or supermarket, or a prefabricated freezer/refrigerator.

The refrigeration system 21 has only the first compressor 1 or the second compressor 2 depending on the load such as whether it is for freezing or refrigeration.
The compressors 1 and 2 are selectively operated individually or simultaneously. The operations of the three on-off valves during each operation are as follows.

First, when operating the first compressor 1 and the second compressor 2 at the same time, open the first and second on-off valves 10 and 11,
Only the third on-off valve 14 is closed. And measuring compressor 10.1
The refrigerant discharged from 1 flows as shown by the solid line arrow. Here, the oil in the refrigerant completely discharged from each compressor 1.degree. 2 is stored in an oil separator 6. Then, the first and second on-off valves 1
, 2 are opened, the air is recovered to the respective compressors 1 and 2 via the first and second branch pipes 8 and 9 (see - dotted chain arrows).

During this simultaneous operation, the third on-off valve 14 is kept closed, so even if there is a difference in pressure within the respective compressors 1 and 2,
There is no fear that oil will flow from the high pressure compressor to the low pressure compressor via the oil equalizing pipe 13.

Next, when operating either the first compressor 1 or the second compressor 2 (for example, individual operation of the first compressor 1), the first on-off valve 10 is opened, and the second and third on-off valves are opened. Valve 11.
Close 14. Then, only the first compressor 1 is operated,
The refrigerant completely discharged from the first compressor 1 is allowed to flow as indicated by the broken line arrow. Here, oil in the refrigerant discharged from the first compressor 1 is stored in the oil separator 6. And the first on-off valve 10
When the oil separator 6 is opened, the oil in the oil separator 6 is recovered to the first compressor 1 via the first branch pipe 10 (see the broken line arrow).

During this individual operation, the pressure in the first compressor 1 is lower than the pressure in the stopped second compressor 2 (for example, 0.05 to 0.07 kg/ cm
”) However, the second and third on-off valves 11.1
By closing 4, even if there is such a pressure difference, the oil in the stopped second compressor 1!2 is prevented from flowing into the operating first compressor 1. In this way, the oil in each compressor 1 and 2 is kept constant, so even if the compressors are operated while they are stopped (switched from individual operation to simultaneous operation), the oil in each compressor 1 and 2 is kept constant. There is no risk that the compressor will run out of oil.

Incidentally, since the movement of each on-off valve during individual operation of the second compressor 2 is shown in the above-mentioned table, a description thereof and a description of the flow of refrigerant and oil will be omitted.

Further, when the first compressor 1 and the second compressor 2 are stopped simultaneously, only the third on-off valve 14 is opened, and the amount of oil in the inner compressor becomes uniform.

(g) Effects of the Invention As described above, the present invention is equipped with a valve that is closed during individual operation in the oil equalizing pipe that connects a plurality of compressors that can be operated individually. is not drawn into the operating compressor. As a result, the oil in the compressor that is not operating can be maintained, and the compressor can be operated without running out of oil.

[Brief explanation of the drawing]

The drawing is a refrigerant circuit diagram showing an embodiment of the present invention.φ・1.2...Compressor, 5...Common discharge pipe, 6
...Oil separator, 7,8.9...Branch pipe, 14
...Third on-off valve (valve).

Claims (1)

[Claims] 1) Equipped with a plurality of compressors that can be operated individually, an oil separator is provided in a common discharge pipe connecting the discharge pipes of each compressor, and the oil separator is connected to each of the compressors. A refrigeration system in which an oil return pipe is provided and the plurality of compressors are connected by an oil equalizing pipe, characterized in that the oil equalizing pipe is provided with a valve that is closed when the plurality of compressors are individually operated. .