JPS63302258A - Refrigerator - 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. This invention relates to a refrigeration system connected in parallel to a refrigerant circuit, and particularly relates to improvements in 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 one oil separator, where lubricating oil dispersed in the refrigerant gas is collected. After being separated, the lubricating oil is supplied to the condenser, while the lubricating oil separated by the oil separator is returned almost equally to each compressor via an oil return pipe.

By the way, when the operating times of the respective 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 returned to each compressor almost equally, so while the amount of 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.
This results 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 amount of oil in the compressor are disclosed in, for example, Japanese Patent Publication No. 40-25038 and Japanese Utility Model Publication No. 53-36600.

(Problem to be Solved by the Invention) However, in the above conventional system, when the operating capacities of the compressors are different, the pressure loss in the suction pipe for the compressor with the larger operating capacity becomes large. Conversely, the dome internal pressure of the compressor is higher in the compressor with the smaller operating capacity. As a result, the refrigerant gas moves from the compressor with a small operating capacity to the compressor with a large operating capacity through the oil equalizing pipe, and the lubricating oil inside the machine also moves in the same direction. When the return amount of oil in the compressor with a small operating capacity is greater than the discharge amount, the lubricating oil above the level of the oil equalizing pipe moves to the compressor with a larger operating capacity through the oil equalizing pipe, and the oil in each compressor is The surface level becomes equal at the oil equalizing pipe position, but conversely, when the return amount of oil is less than the discharge amount, the oil level in the compressor with a small operating capacity decreases over time. The lubricating oil in the compressor 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 lubricating oil level drops below the operating oil level. The supply to the lubricating parts will be cut off, resulting in damage to the compressor.

Therefore, the applicant first filed the patent application No. 60-227519.
In the specification and drawings, when a plurality of compressors are provided, the plurality of compressors are communicated with each other by oil equalizing pipes, and the operating capacity of the six compressors is controlled for a predetermined period of time based on a predetermined operation mode. By controlling the pressure to increase or decrease sequentially at each compressor, while ensuring sufficient refrigerating capacity of the equipment by continuing to operate the compressor, the difference in dome internal pressure caused by the increase or decrease in the operating capacity of each compressor, We have proposed a system in which lubricating oil is moved between each compressor via oil equalizing pipes to ensure that the amount of oil in each compressor is equalized.

However, when performing oil equalization operation based on the capacity increase/decrease control of each compressor as described above, if the refrigeration equipment becomes overloaded during this oil equalization operation, the compression The capacity of the compressor is reduced, but with this control, the compressor capacity cannot be controlled to increase during the oil equalization operation, resulting in the drawback that it becomes difficult to equalize the oil between the compressors. .

The present invention has been made in view of the above, and focuses on the fact that when all the compressors are stopped, the pressure difference between the domes disappears through the oil equalizing pipe, and its purpose is to If the oil equalization operation and the equipment overload prevention control are performed at the same time, the compressor can be actively stopped and controlled to effectively prevent the equipment from overloading.
When the compressor is stopped and there is no pressure difference between the domes, the lubricating oil is moved by its own weight to the side with less oil to equalize the oil between the compressors.
Therefore, the objective is to simultaneously exhibit an overload prevention function and an oil equalization function.

(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, there are multiple variable capacity compressors (1), (2).
) are connected in parallel to one refrigerant circuit. And each of the above compressors (1), (2)
The insides of the domes (4) are communicated by oil equalizing pipes (10) that communicate with each other at the operating oil level of the lubricating oil (A), and
A normal time control means (14) is provided for controlling the operating capacity of each of the compressors (1) and (2) to be sequentially changed at predetermined time intervals based on a predetermined operation mode. Further, a filtration load detection means (17) detects when each of the compressors (1) and (2) is overloaded, and the compressor (1) ), and overload control means (18) which controls the operation of (2) to be stopped with priority over the normal control means (14).

(Function) With the above configuration, in the present invention, when the plurality of variable displacement compressors (1) and (2) are operated, the oil amount balance in each dome may be disrupted, but in this case, The operation of each compressor (1), (2) is controlled by the normal control means (14), and the operating capacity of each compressor (1) and (2) is sequentially increased or decreased at predetermined time intervals based on a predetermined operation mode, so that the internal pressure of each dome is Differences occur sequentially, and as a result, the lubricating oil (A) in each dome moves through the oil equalizing pipe (10) based on the differential pressure, and the oil amount in each compressor (1), (2) becomes equal. be done.

When the device becomes overloaded during the oil equalization operation as described above, the overload control means (18) takes priority over the normal control means (14) and controls all the compressors (1), (2). operation is controlled to stop. Although this eliminates the refrigerating capacity of the device, it prevents the compressors (1) and (2) from being overloaded, and eliminates the pressure difference between the inner phase tiles of each dome (4), resulting in lubrication. The oil moves to the side with less oil due to its own weight via the oil equalizing pipe (10), and the amount of oil between the compressors is equalized.

(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 the present invention. In the figure, (1) and (2) are variable capacity first and second compressors connected in parallel to one refrigerant circuit, and the six compressors (1).

(2) each have an electric motor (5) inside a sealed dome (4).
and a compressor main body (7) connected to the drive shaft (6) of the electric motor (5) and whose capacity is variably adjusted by an inverter (15), which will be described later. , lubricating oil (
A) is stored.

Also, the above 1. The domes of the second compressors (1) and (2) (
4) and (4) are connected by an oil equalizing pipe (10) so that the inside thereof is communicated at the operating oil level position of the lubricating oil (A), and the lubricating oil (A) is connected through the oil equalizing pipe (10). It is possible to move between the recompressors (1) and (2) via the compressor.

Further, (8) is a suction pipe for sucking refrigerant gas into the dome (4) of each of the compressors (1) and (2), and the suction pipe (8) is connected to the main piping section (8a). ), and two sub-piping parts (
8b) and (8b), and the downstream end of each sub-piping section (8b) is connected to the dome (1) and (2) of the compressor (1) and (2), respectively.
4) It is opened in the improvement part. Further, (9) is a discharge pipe for discharging the refrigerant gas compressed by the compressor body (7) of each of the compressors (1), (2) to the outside of each dome (4). The discharge pipe (9) is connected to each compressor (1), (2)
a sub-piping section (9b) connected to the compressor main body (7);
(9b) and the sub-piping section (9b), (9b)
The main piping section (9a) is connected to the downstream end of the main piping section (9a). Thus, each compressor (1).

In (2), the refrigerant gas sucked into the dome (4) through the suction pipe (8) is compressed by the compressor body (7), and then discharged to the outside of the dome (4) through the discharge pipe (9). It is composed of

In addition, each sub-piping section (9b) of the discharge pipe (9) includes:
An oil separator (11) that separates the lubricating oil (A) from the refrigerant gas discharged to the outside of the dome (4) by the sub-piping section (9b).
), (11) are individually installed for each compressor (1), (2), and the six oil separators (11) are connected to the suction pipe (8) through an oil return pipe (12), respectively. Each corresponding sub-piping section (8b).

(8b) and each oil separator (11).

The lubricating oil (A) separated in (11) is transferred to each oil return pipe (1
2) and suction pipes (8) to the corresponding compressors (1) and (2). Also,
Each of the above oil return pipes (12).

Capillaries (13) are interposed in each of (12), and the amount of oil returned into the dome (4) of each of the compressors (1) and (2) is returned by these capillaries (13) and (13). is controlled.

Furthermore, during oil equalization operation, the operating capacity of each of the compressors (1) and (2) is set in advance by a controller (14) as a normal control means, and is sequentially increased or decreased at predetermined intervals based on the operating mode. controlled to do so. A specific example of this control will be explained with reference to FIG. 2. Let us assume that before the oil equalization operation, for example, the first compressor (1) has a large amount of oil and the second compressor (2) has a small amount of oil. , first, first
In step S1, the operating capacity of the first compressor (1) is set to 100%.
The operating capacity of the second compressor (2) is controlled to 50%. Therefore, the dome internal pressure of the second compressor (2) with a low operating capacity is high, and it is low in the first compressor (1) with a high operating capacity, but the second compressor (2) has a small amount of oil and the oil equalizing pipe (
Since it does not reach the height position of 10), the lubricating oil (A) is
The oil does not move from the compressor (2) to the first compressor (1), and the amount of oil in each compressor (1), (2) remains the same as before the oil equalization operation.

Next, when moving from the first step $1 to the second step S2, the operating capacity of the first compressor (1) is controlled to 50%, and the second compression 'll& (2) is controlled to 100%. Therefore, this time, the dome internal pressure of the first compressor (1) is high and the pressure of the second compressor (2) is low, and the lubricating oil (A) of the first compressor (1), which has a large amount of oil, is transferred to the oil equalizing pipe ( 10) through the second
Move to compressor (2), then both compressors (1), (2)
The amount of oil in between is equalized.

Furthermore, in FIG. 1, the controller (14) is equipped with the compressors (1) for overload protection of the refrigeration system.
, (2) The drooping signal from the inverter (15) that changes the drive frequency of the electric motor (5) (outputted at a slightly lower current value than in the trip state) can be manually operated, and the high pressure of the refrigerant A close signal (high pressure signal) from a pressure switch (16) that closes at a refrigerant discharge pressure value slightly smaller than the operating pressure value of a protection device (not shown) can be input, and the inverter (15) and pressure switch (16)
The first and second compressors (1).

(2) Overload detection means (17) configured to detect overload is configured.

As shown in FIG.
When a drooping signal or a high pressure signal (that is, an overload signal) is input from the compressor (in the figure, when the drooping signal is input manually), oil equalization operation is stopped at that point, and the capacity of both compressors (1) and (2) is The value is set to zero, that is, it is controlled to stop, and this stopped state is maintained for a predetermined period of time (
For example, for 4 minutes), it functions to maintain

Therefore, the controller (14) prioritizes the operation of both compressors (1) and (2) over the normal control means (14) when an overload is detected by the two-legged overload detection means (17). Overload control means (18
).

Therefore, in the above embodiment, even if an imbalance of oil amount occurs in each compressor (1), (2) during normal operation of the refrigeration system, during oil equalization operation, each compressor (1)
), (2) are controlled by the normal control means (controller 14) to increase or decrease sequentially at predetermined time intervals as shown in FIG.
By continuing the operation of (2), while ensuring a good refrigerating capacity, a pressure difference is created between the domes (4) of each compressor (1) and (2), and lubricating oil (A) is produced from more to less lubricating oil (A). The unbalance of the oil amount mentioned above is resolved, and each compressor (
The amount of oil in the dome (4) of 1) and (2) is reliably made uniform.

During the oil equalization operation, as shown in Figure 2, the first
And due to the alternate capacity increasing operation (100% operation) of the second compressors (1) and (2), the refrigerant discharge pressure increases and the current value of each inverter (15) increases. , equipment may become overloaded. However, in this case, as shown in FIG. 3, for example, when the drooping signal of the inverter (15) is output in the second step S2 of the oil equalization operation mode, both compressors (1) and (2) Since the operation is stopped for a predetermined period of time (4 minutes) under the control of the overload control means (18), the overload of each compression a (1) and (2) is effectively prevented, and the dome (4) When the pressure difference between the inner tiles disappears, the lubricating oil (A) moves by its own weight from the larger side to the smaller side through the oil equalizing pipe (10) during this predetermined time (4 minutes) and is recompressed. Machine (1), (2)
This will equalize the amount of oil between them.

After the predetermined time has elapsed, normal operation is resumed. Therefore, if it becomes necessary to perform overload protection control during lubricating oil equalization operation, the compressor (1).

While effectively preventing the overload (2), the lubricating oil can be uniformized well, and the reliability of the lubricating oil equalizing operation can be improved.

In the above embodiment, there are two compressors (1).

Although (2) was used, it goes without saying that the number of compressors may be three or more, and the operation mode of the oil equalization operation is not limited to the above specific example, but may be any other operation mode. , it is possible to equalize the amount of oil.

(Effects of the Invention) As explained above, according to the refrigeration system of the present invention, by controlling the operating capacity of each compressor to increase/decrease sequentially, a pressure difference is sequentially generated between each dome and the oil amount is made uniform. In case of
If equipment overload protection control is requested at the same time during this oil equalization operation, the operation of each compressor is forcibly stopped to effectively protect each compressor from overload, and each dome is The pressure difference between the inner and outer parts is eliminated, and the lubricating oil is moved by its own weight to the side with less oil to equalize the oil amount, so even when overload protection is required, the oil amount can be maintained while effectively providing overload protection. can be made uniform, and its reliability can be improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 is a schematic configuration diagram of a refrigeration system, Fig. 2 is a diagram showing a normal operating mode of the compressor controlled by a controller, and Fig. 3 is a diagram showing an overload protection mode. It is a figure which shows the operating mode of a compressor at the time of a request. (1)...First compressor, (2)...Second compressor, (
4)...Dome, (8)...Suction pipe, (9)...
Discharge pipe, (10) Oil equalizing pipe, (14) Controller, (A) Lubricating oil, (17) Normal control means, (18) Overload control means.

Claims (1)

[Claims] (1) In a refrigeration system in which a plurality of variable capacity compressors (1) and (2) are connected in parallel to one refrigerant circuit,
The insides of the domes (4) of each of the compressors (1) and (2) are communicated with each other by oil equalizing pipes (10) that communicate with each other at the operating oil level of the lubricating oil (A), and Machine (1)
, (2) normal-time control means (
14), and overload detection means (17) for detecting overload of each of the compressors (1) and (2); The operation of the compressors (1) and (2) is controlled by the normal control means (14).
) Overload control means (
18) A refrigeration device comprising: