JPS6287771A - Refrigeration equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a single system of variable capacity compressors that compresses refrigerant gas sucked into a dome through a suction pipe and discharges the compressed gas through a discharge pipe. The present invention relates to a refrigeration system connected in parallel to a refrigerant circuit, and particularly relates to measures for equalizing oil between compressors.

(Prior Art) Generally, in such a refrigeration system, refrigerant gas discharged from each compressor is collected together and sent to an oil separator.
After the lubricating oil dispersed in the refrigerant gas is separated here, it is supplied to the condenser, while the lubricating oil separated in the oil separator is distributed almost equally to each compressor via the oil return pipe. The oil is being returned.

By the way, when the operating times of the compressors are different, the amount of lubricating oil dispersed in the refrigerant gas during operation is larger on the compressor side with a longer operating time than on the compressor side with a shorter operating time. However, as mentioned above, the lubricating oil dispersed in the refrigerant gas is distributed almost equally to each compressor and returned, so the amount of KrI lubricating oil in the compressor that operates for a long time gradually decreases. , the amount of lubricating oil in the compressor that operates for a short time gradually increases, resulting in an imbalance in the amount of oil in each compressor. Then, when the amount of oil in the compressor gradually decreases and the oil level falls below the operating oil level, the supply of lubricating oil to the lubricating parts is cut off, and there is a risk that the compressor will be damaged.

Conventionally, in order to eliminate the imbalance in the amount of oil in each of the compressors, each compressor was communicated with an oil equalizing pipe, and the lubricating oil was moved from the side with more oil amount to the one with less oil amount. Compressors designed to equalize the oil m in the compressor are disclosed in, for example, Japanese Patent Publication No. 4C-25038 and Japanese Utility Model Publication No. 36600-1983.

(Problems to be Solved by the Invention) However, in the conventional system described above, if the operating capacities of the compressors are different, the pressure loss in the suction pipe for the compressor with the larger operating capacity increases. Conversely, the pressure inside the dome of the compressor is higher in the compressor with the smaller operating capacity, and as a result, the refrigerant gas moves from the compressor with the smaller operating capacity to the larger compressor through the oil equalizing pipe, and the lubricating oil inside the machine When the return amount of oil in the compressor with the small operating capacity Δl is greater than the discharge amount, the lubricating oil above the level of the oil equalizing pipe passes through the oil equalizing pipe to the compressor with the larger operating capacity. The oil level in each compressor becomes equal at the oil equalization pipe position, but conversely, when the oil return is less than the discharge amount, the oil level in the compressor with a smaller operating capacity becomes equal. At this time, the lubricating oil in the compressor with a large operating capacity is prevented from moving to the compressor with a smaller operating capacity due to the difference in the dome internal pressure of each compressor), and eventually the oil level If the oil level falls below the operating oil level, the supply of lubricating oil to the lubricating parts will be cut off, resulting in damage to the compressor.

Therefore, in order to solve this problem, by making the oil equalizing pipe that communicates within each compressor larger in diameter, even when the oil return interval as described above is smaller than the discharge amount, the lubricating oil can be It is conceivable that the refrigerant gas can be moved in the opposite direction of the flow direction of the refrigerant gas from the compressor with a small operating capacity to the compressor with a large operating capacity, that is, from the compressor with a large operating capacity to the compressor with a small operating capacity, due to the difference in the internal pressure of the dome.

However, when using this large-diameter oil equalizing pipe, the vibrations generated in one compressor are transmitted through the oil equalizing pipe to the pressure of the other compressor.
This is easily transmitted to the machine, complicates the imaging mode, and makes it impossible to adopt a complicated pipe shape to prevent the occurrence of traps in the oil equalizing pipe, making it difficult to ensure sufficient strength of the oil equalizing pipe. The problem arises that

In addition, as another solution to equalize the amount of oil in each compressor connected by an oil equalizing pipe, the amount of lubricating oil returned from the oil separator to each compressor can be controlled by using, for example, a foot type regulator. Possible methods include controlling the solenoid valve by opening and closing it based on signals from an oil level sensor that detects the curved surface inside each compressor, but this increases the number of control parts and increases the cost of the device. In addition to increasing the size of the system, the control unit also tends to lack reliability.

The present invention has been made in view of these points, and its purpose is to return lubricating oil separated by the oil separator to each compressor in a refrigeration system equipped with the oil equalizing pipe described above. By taking control measures corresponding to the operating capacity of the 8-pressure m machine, it is possible to prevent the increase in vibration to the compressor and the decrease in the strength of the oil equalizing pipe due to the use of a large diameter oil equalizing pipe, and to prevent the control parts from increasing. The objective is to equalize the amount of oil in each compressor while preventing an increase in cost and a decrease in reliability due to an increase in oil.

(Means for solving the problem) In order to achieve the above object, the solving means of the present invention is as follows:
As shown in the figure, a plurality of variable capacity compressors (1), ( 2), (3
) are connected in parallel to one refrigerant circuit. 1. The inside of the dome (4) of each of the above compressors (,1), (2), (3) is operated with lubricating oil (A>). The oil is discharged to the outside of the dome (4) of each compressor 111 (1), (2), (3) by the oil equalizing pipes (10), (10) communicating with each other at the oil level position and the discharge pipe (9). An oil separator (11) separates lubricating oil (A) from the collected refrigerant gas, and the lubricating oil (A) separated by this oil separator (11) is compressed to 1 M!
(1), (2), and (3) return oil return pipes into the dome (4), respectively <12).

(13), (14), and each oil return pipe (12).

A solenoid valve (15) that opens and closes (13) and (14).

(16) and (17) are provided. Furthermore, the operating capacity of each compressor (1) +' (2), (3) is detected, and as the operating capacity of each compressor (1), (2), (3) increases, the combined compressor Solenoid valves corresponding to (1), (2), and (3) (
15), (16), and (17) so that the opening time becomes longer.
Each solenoid valve (15).

(16) and (17) to each compressor (1) and <2>.

(3) A controller that controls opening and closing according to the operating capacity (
1 day).

(Function) With the above configuration, in the present invention, a plurality of variable capacity compression units R<1), (2
), (3>) The refrigerant gas sucked into each dome (4> by the suction pipe (8)
After being compressed by, the lubricating oil (A) is discharged through the discharge pipe (9) and separated by the oil separator (11), and the lubricating oil (△) separated by the oil separator (11) is the oil return pipe (
12).

Each of the above compressions 1a (1') is processed through (13) and (14).

(2) and (3) are returned into the domes (4), respectively.

At that time, the oil return pipes (12), (13).

(14) Solenoid valves (15) and (16) that open and close.

(17) is controlled to open and close by a controller roller (18) that receives the operating capacity of each of the compressors (1), (2), and (3) as an input signal, and is a compressor (1) with a large operating capacity; (2)
, (3) corresponding solenoid valves (15), (16), (17
) is kept open for a longer time than the solenoid valves (15), (16), and (17) corresponding to compressors (1), (2), and (3) with small operating capacities, and compressors with large operating capacities! a(1),(2
), the number of oil return machines for (3) will be increased. For this reason, large operating capacity compressors (1) and (2>
.

Even if the oil amount in (3) decreases, this decreased oil amount will cause the solenoid valves (15), (16), and (17) to open for the above long time.
each compressor (1), (2
) and (3), the oil level will be made uniform.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a schematic configuration of a refrigeration system according to an embodiment of the present invention, in which (1), (2), and (3) are variable capacity first refrigeration systems connected in parallel to one refrigerant circuit. 2nd and 3rd
The combined compressors (1), (2), and (3) are connected to a drive shaft (6) of an electric motor (5) and an i-motor (5) in a sealed dome (4). compressor body〈7)
The compressor body (
Lubricating oil (A) to be supplied to the lubricating section 7) is stored. Note that the variable displacement compressor may be one that unloads cylinders, one that is driven by an inverter, one that uses a pole number conversion motor, or the like.

Also, the above 1. The dome of the second compression n(1), (2) (
4), between (4) and 2nd. Third compressor (2), (3)
An oil equalizing pipe is installed between the domes (4) and (4) so that the inside thereof communicates with each other at the operating oil level position of the lubricating oil (△).
10) and (10), and the lubricating oil (A) is supplied to the oil equalizing pipe (10).

It is possible to move between the compressors (1), (2), and (3) via the compressors (10).

Further, (8) is a suction pipe for sucking refrigerant gas into the dome (4) of each of the compressors (1), (2), and (3), and the suction pipe (8) is connected to the main pipe. Part (8a) and
It consists of three sub piping parts (8b), (8b), (8b) branched and connected to the main piping part (8a), and the downstream end of each sub piping part (8b) is compressed by compression 1 (1). ,(2
), the dome of (3) <4) is opened to the upper part. In addition, (9) transfers the refrigerant gas compressed by the compressor body (7) of each of the above compressors (1), (2), and (3) to each dome (4).
A discharge pipe for discharging to the outside, the discharge pipe (9) is connected to the compressor body (7) of each compressor <1), (2), (3).
Sub piping section (9b), (9b), (9b) connected to
and a main piping section (9a) connected to the downstream end of the nub piping section (9b), (9b), (9b).Therefore, each compressor (1), <2), (3) Now, the suction pipe (8)
After the refrigerant gas sucked into the dome (4) is compressed by the compressor body (7), it is sent to the dome (4) via the discharge pipe (9).
4) Constructed to discharge to the outside.

In addition, lubricating oil is supplied to the discharge pipe (9) from the refrigerant gas discharged outside the dome (4) of each compressor (1), (2), and (3) through the discharge pipe (9). An oil separator (11) is interposed to separate the oil from the air (A), and the oil separator (11) is connected to the reave-arranged portion of the suction pipe (8) leading to the dome (4) of the first compressor (1). (8b) via a first oil return pipe (12), and a second oil return pipe (13) and a third oil return pipe (14) are connected to the first oil return pipe (12). ) are branched and connected to each other, and the second oil return pipe (13
) is the other end of the suction pipe (8) leading to the dome (4) of the second compressor (2). 1γ16 (8b), the other end of the third oil return pipe (14) is connected to the dome (
The lubricating oil <A> separated by the oil separator (11) is connected to the sub-piping parts (8b) of the suction pipe (8) leading to the first pipe (8). Second and third oil return pipes (12).

(13) and (14) to each of the above compressors (1).

<2) and <3), respectively.

Furthermore, the second oil return pipe (12) of the first oil return pipe (12) is
3) A first oil return pipe (12) is located downstream of the connection with
A first solenoid valve (15) that opens and closes the second oil return pipe (13), a second solenoid valve (16) that opens and closes the second oil return pipe (13), and a third solenoid valve (16) that opens and closes the second oil return pipe (13). The return pipe (14) has a third solenoid valve (17) that opens and closes the third oil return pipe (14).
are interposed respectively, and these solenoid valves (15).

By opening and closing (16) and (17), the first oil separator 11) is opened and closed. Second and third compressors (1), (2)
, (3) is returned or stopped.

These first, second and third solenoid valves (15).

The opening/closing control of (16) and (17) is controlled by the controller (18).
This is done by The controller (18) includes a first operating sensor (19) that detects the operating capacity of the first compressor (1), and a second operating sensor that detects the operating capacity of the second compressor (2). capacity S sensor (20) and the third compressor (
3) Third operating sensor (21) that detects the operating capacity of
The controller (18) controls each compression 1! according to the operating capacity of each compressor (1), (2), and (3). (1), (2>.

Each of the above solenoid valves (15), (16), (corresponding to (3))
17) Compressor (1) with opening/closing control and large operating capacity;
Solenoid valves (15), (16) corresponding to (2), <3),
(17) A small compressor (1) that operates the opening time of '3';
Solenoid valves (15), <16) corresponding to (2) and (3),
The opening time is controlled to be longer than the opening time of <17).

The n-close mode of each of the above electromagnetic valves <15), <16), and <17) is illustrated in FIG. The figure shows a case where the operating capacity of the first compressor (1) is set to 100%, and the operating capacities of the second and third compressors (2) and (3) are both set to 50%.
Assuming that the opening time of the first solenoid valve (15) corresponding to the first compressor (1) is (time (for example, 1 minute)), the 2,3 thunder valve (16)
, <17> is set so that the opening time of each solenoid valve (15), (16), and (17) is half t/2 (for example, 30 seconds) according to the above operating capacity ratio, and that each solenoid valve (15), (16), and (17) is opened at 1 o'clock. It is set to listen every 5 minutes, for example.

Therefore, in the above embodiment, when the refrigeration system is in operation, the operating capacities of the compressors (1), (2), and (3) are the first, second, and third . Operating capacity Senna (19), (
20) and (21), and the controller (18) receiving this detection signal selects each solenoid valve <15) according to the operating capacity.

Control signals are output to (16) and (17). and,
As mentioned above, the operating capacity of the first compressor (1) is 100%, and the operating capacities of the second and third compressors (2) and (3) are both 50%.
%, in the first compressor (1) with a large operating capacity, the second compressor (1) with a small operating capacity M. Third compressor (2), (
3), the amount of lubricating oil (A) in the dome (4) of the other compressors (2), (3), and (4) It will be less than within. However, in the case of this embodiment, as shown in the opening/closing mode of FIG. Third
Depending on the operating capacity of the compressors (2) and (3), the opening time t of the first solenoid valve (15) corresponding to the first compressor (1) is different from that of the other 2nd and 3rd compressors ( 2), the second corresponding to (3)
．． 3ffi magnetic valve (16), (17) opening time t/2 2
Since the dome of the first compressor (1) (
4) Inward (D Return oil ffi $ etc. (7) 2.3 Compression 11 (2), ゛ The amount of oil returned into the dome (4) of (3) is larger than that of (4), (4), and this causes , the decrease in lubricating oil (A) in the first compressor <1) is compensated for in each compression IN<1>.

It is possible to equalize the oil level in (2) and (3).

Also, each compressor (1), (2) as described above.

Even if we try to equalize the oil level in each compressor (1),
It is thought that there are slight differences in the amount of oil discharge, oil return, or suction pressure loss in (2) and <3>. Therefore, if this state continues for a long time, each compressor (1) may be damaged depending on the operating conditions.

The difference in oil level between (2) and (3) increases, and each compressor (
An imbalance in the amount of oil will occur in the domes (4) of 1), (2), and (3). In order to prevent this, the operating capacities of the compressors (1), (2), and (3) are changed sequentially at predetermined intervals based on the operating mode preset by the controller (18). The operation may be controlled accordingly. That is, according to this, even if an imbalance of oil amount occurs in the dome (4) of each compressor (1), (2), (3), each compression is 1 m (1).

The dome (4) of each compressor (1), (2), (3) is caused by the difference in the dome internal pressure based on the change in the operating capacity of (2), (3).
) through the oil equalizing pipes (10) and (10).
is moved, and it is possible to reliably equalize the oil level in each compressor (1), (2), and (3).

In general, each of the above oil return pipes (12) and (13).

(14) is provided with a capillary that bypasses the solenoid valves (15), (16), and (17).
Even if compressors (5), (16), and (17) fail, each compressor (1)
, (2), (3) with each compression a<1), (
It is also possible to prevent damage in 2) and (3). In this case, each solenoid valve (1
Each compression 11(1) even when 5), (16), (17) are closed.

Oil is always returned to (2) and (3), but the capillary size is changed to compressors (1) and (2) with large operating capacity.
There is no problem if the amount of oil returned to (3) is set to be slightly larger than that for small operation.

(Effects of the Invention) As explained above, according to the present invention, the refrigeration system is constructed by connecting a plurality of variable capacity compressors <1), (2), and (3) in parallel to one refrigerant circuit. In the equipment, an oil separator (1
The compressor lubricating oil (A) separated in step 1) is transferred to the oil return pipe (1).
2), (13).

, (14) to the compression W(1), (2), (3>), each oil return pipe (12), (13).

The solenoid valves (15), (16), and (17) in (14) are set so that the opening time becomes longer as the operating capacity increases, according to the operating capacity of the corresponding compressor (1), (2), and (3). Since the opening/closing is controlled at
), (2), and (3) using a small operating capacity compressor (
1), (2).

(3) can be more than (1), so the compressor (1)
, (2), and (3) can be reliably made uniform.

In addition, each compressor (1), (2) in this way.

(3) It is possible to use a small-diameter oil-equalizing pipe (1o) by ensuring oil equalization between 1q, and by using a large-diameter oil-equalizing pipe, it is possible to increase the amount of movement to the meat compressor and reduce the oil-equalizing pipe. It is possible to prevent the strength from decreasing.

Furthermore, each compressor (1) does not require control parts such as a float regulator or oil level sensor.

Since oil equalization (2) and (3) can be performed, it is also possible to reduce costs and improve reliability in terms of control.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a refrigeration system according to an embodiment of the present invention,
FIG. 2 is a diagram showing the opening/closing mode of each solenoid valve as the operating capacity of each compressor changes. (1)...First compressor, (2)...Second compressor, (
3)...Third compressor, (4)...Dome, (8)...
... Suction pipe, Ku> ... Discharge pipe, (10) ... Oil equalizing pipe, (11) ... Oil separator, (12) ... First oil return pipe, (13) ... Second oil return pipe, (14>...Third curved return pipe, (15)...First solenoid valve, (16)...
・Second solenoid valve, (17),...Third solenoid valve, (18)
...To con 1 []-ra, <A)...Lubricating oil.

Claims (1)

[Claims] (1) Multiple variable displacement compressors (1), (2), (3) that compress refrigerant gas sucked into the dome (4) through the suction pipe (8) and discharge it through the discharge pipe (9). ) are connected in parallel to one refrigerant circuit. The oil is discharged and collected outside the dome (4) of each compressor (1), (2), (3) by the oil equalizing pipes (10), (10) communicating with each other at the position and the discharge pipe (9). an oil separator (11) that separates lubricating oil (A) from refrigerant gas; 3
) oil return pipes (12) returning into the domes (4) of
(13), (14) and these oil return pipes (12), (1
3), Solenoid valves (15), (16), which open and close (14),
(17) and each solenoid valve (15), (16), (17)
According to the operating capacity of each compressor (1), (2), (3), the opening time becomes longer as the operating capacity of each compressor (1), (2), (3) increases. A refrigeration system comprising: a controller (18) for controlling opening and closing of the refrigeration system.