JPH065140B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides two variable capacity compressors each having one system in which refrigerant gas sucked into a dome by a suction pipe is compressed and discharged by a discharge pipe. The present invention relates to a refrigerating device connected in parallel to a refrigerant circuit, and particularly to a measure for achieving oil equalization between compressors.

(Prior Art) Generally, in such a refrigeration system, the refrigerant gas discharged from each compressor is collected together and sent to the oil separator,
Here, the lubricating oil dispersed in the refrigerant gas is separated and then supplied to the condenser, while the lubricating oil separated by the oil separator is almost evenly distributed to both compressors via the oil return pipe. It is designed to return oil.

By the way, when the operating times of the two compressors are different, the amount of lubricating oil dispersed in the refrigerant gas during operation is larger on the side of the compressor having a longer operating time than on the side of the compressor having a short operating time. However, since the lubricating oil dispersed in this refrigerant gas is distributed evenly to both compressors and returned as described above, while the amount of lubricating oil in the compressor with a long operating time gradually decreases, The amount of lubricating oil in the compressor with a short time gradually increases,
An imbalance in the amount of oil will occur in both compressors.
When the amount of oil in the compressor gradually decreases and the oil level drops below the operating oil level, the supply of lubricating oil to the lubrication section is cut off, which may damage the compressor.

Therefore, conventionally, in order to eliminate the imbalance of the oil amounts in the both compressors, both the compressors are communicated with each other through an oil equalizing pipe, and the lubricating oil is moved from the one with a large oil amount to the one with a small oil amount. A device designed to make the amount of oil in the compressor uniform is disclosed in, for example, Japanese Patent Publication No. 40-25038 and Japanese Utility Model Publication No. 53-36600.

(Problems to be solved by the invention) By the way, in the above-mentioned conventional compressor, when the operating capacities of the two compressors are different from each other, the pressure loss of the suction pipe with respect to the compressor having the larger operating capacity becomes large. On the contrary, the dome internal pressure of the machine becomes 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 compressor with the larger operating capacity through the oil equalizing pipe, and the lubricating oil in the machine also increases. Move in the same direction. When the amount of oil returned in the compressor with a small operating capacity is larger than the discharge amount, the lubricating oil above the oil equalizing pipe level moves into the compressor with a large operating capacity through the oil equalizing pipe, and the oil in both compressors is discharged. The oil level becomes equal at the oil level pipe position, but conversely, when the oil return amount is less than the discharge amount, the oil level in the compressor with a small operating capacity decreases with the passage of time (at this time, the operating capacity The lubricating oil in the large compressor is prevented from moving to the compressor with a smaller operating capacity due to the difference in the dome internal pressure of both compressors), and finally the lubricating oil is reduced by the oil level falling below the operating oil level. The supply of oil to the lubrication section is cut off, resulting in damage to the compressor.

Therefore, in order to solve this problem, by making the oil equalizing pipes communicating between both compressors to have a large diameter, even when the oil return amount as described above is smaller than the discharge amount, the lubricating oil is It is conceivable that due to the difference in the dome internal pressure, the refrigerant gas flowing from a compressor with a small operating capacity to a compressor with a large operating capacity can move in the opposite direction, that is, from a compressor with a large operating capacity to a compressor with a small operating capacity.

However, when using this large-diameter oil equalizing pipe, the vibration generated in one compressor is easily transmitted to the other compressor via the oil equalizing pipe, the vibration mode becomes complicated, and the trap in the oil equalizing pipe becomes complicated. Since a complicated pipe shape cannot be adopted to prevent the occurrence, there arises a problem that it becomes difficult to secure sufficient strength of the oil equalizing pipe.

Further, as another solution for equalizing the oil amounts in both compressors connected by an oil equalizing pipe, a method of adjusting the oil amount of the lubricating oil returning from the oil separator into each compressor by using, for example, a float regulator Alternatively, a method of controlling by opening and closing the solenoid valve by a signal from an oil level sensor that detects the oil level in each compressor can be considered, but since the number of control parts increases by that amount, it is possible to increase the cost of the device. In addition to this, there is a tendency to lack reliability in terms of control.

The present invention has been made in view of the above points, and an object of the present invention is to specify a return destination of lubricating oil separated by an oil separator to both compressors, and then, in association with that, By adjusting the internal pressure of the dome of the compressor, it is possible to prevent an increase in vibration to the compressor and a reduction in the feeling of oil level due to the use of a large-diameter oil equalizing pipe. It is to prevent the deterioration of reliability and to make the amount of oil in both compressors uniform, and also to simplify the devices such as the refrigerant circuit and the control circuit.

(Means for Solving the Problem) In order to achieve the above object, the solution means of the present invention is
As shown in the figure, two variable displacement compressors (1), (2) that compress the refrigerant gas sucked into the dome (3) by the suction pipe (8) and discharge it by the discharge pipe (9). The operating oil level of the lubricating oil (A) in the dome (3), (3) of both compressors (1), (2) for the refrigerating device in which the refrigerant is connected in parallel to the refrigerant circuit of one system. An oil equalizer pipe (7) communicating at a position, an oil separator (11) for separating the lubricating oil (A) from the refrigerant gas discharged outside the dome (3) by the discharge pipe (9), and this oil separation Oil return pipe (12) for returning the lubricating oil (A) separated in the vessel (11) only into the dome (3) of one of the compressors (1) and (2)
And. Further, the dome internal pressure of one compressor (2) to which the lubricating oil (A) is returned is always the other compressor (1).
The operating capacity control means (16) for controlling the operating capacities of the compressors (1) and (2) is provided so as to be higher than the above.

(Operation) With the above configuration, in the present invention, the two variable displacement compressors (1), (2) connected in parallel to the refrigerant circuit of one system
The refrigerant gas sucked by the suction pipe (8) into each dome (3) is compressed by both compressors (1), (2) and then discharged through the discharge pipe (9) to separate the oil. Bowl (11)
The lubricating oil (A) is separated by, and the lubricating oil (A) separated by the oil separator (11) passes through an oil return pipe (12) and is fed to one of the compressors (1) and (2). It is only returned in the dome (3) of the compressor (2).

At this time, the operating capacity control means (16) causes the lubricating oil (A) to be returned so that the dome internal pressure of one compressor (2) is always higher than that of the other compressor (1). The operating capacities of 1) and (2) are controlled. Therefore, due to the difference in the dome internal pressure between the compressors (1) and (2), the lubricating oil (A) passes through the oil equalizing pipe (7) from the compressor (2) side with the high dome internal pressure to the low compressor (1) side. The amount of oil in the compressor (2) that moves to the side and the dome internal pressure is high,
This reduced oil amount is compensated by the oil return through the oil return pipe (12), and thus the oil levels in both compressors (1) and (2) are surely made uniform.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows a schematic structure of a refrigerating apparatus according to an embodiment of the present invention, and (1) and (2) are first and second variable capacity compressors connected in parallel to one system refrigerant circuit. The compressors (1) and (2) are connected to the electric motor (4) and the drive shaft (5) of the electric motor (4) in the closed dome (3). And the lubricating oil (A) supplied to the lubricating portion of the compressor body (6) is stored at the inner bottom portion of each dome (3). The variable displacement compressor may be one that unloads the cylinder, one that is driven by an inverter, or one that uses a pole number conversion motor.

Also, the dome (3) of both compressors (1), (2),
(3) is connected by an oil equalizing pipe (7) so that the inside thereof communicates with the operating oil surface level position of the lubricating oil (A), and the lubricating oil (A) is compressed by both oils through the oil equalizing pipe (7). Machine (1),
(2) It is designed to be able to move between.

Further, (8) is a suction pipe for sucking the refrigerant gas into the dome (3) of each of the compressors (1) and (2), and the suction pipe (8) includes the collecting pipe portion (8a). ) And a branch pipe part (8) branched and connected to the downstream end of the collecting pipe part (8a).
b) and (8b), each branch pipe section (8b), (8)
The downstream ends of b) are opened in the upper portions of the domes (3) and (3) of the compressors (1) and (2), respectively. Also, (9)
Is a discharge pipe for discharging the refrigerant gas compressed by the compressor body (6) of each compressor (1), (2) to the outside of each dome (3), and the discharge pipe (9) is , Each compressor (1),
Branch pipe parts (9b), (9b) connected to the compressor bodies (6), (6) of (2), and the branch pipe parts (9b), (9).
b) and a collecting pipe portion (9a) connected to the downstream end. Therefore, in each compressor (1), (2), the suction pipe (8)
The refrigerant gas sucked into the dome (3) is compressed by the compressor body (6) and then discharged to the outside of the dome (3) through the discharge pipe (9).

Further, an oil separator (11) for separating the lubricating oil (A) from the refrigerant gas discharged outside the domes (3) and (3) by the discharge pipe (9) is interposed in the discharge pipe (9). The oil separator (11) is connected to the lower part of the dome (3) of the second compressor (2) through an oil return pipe (12), and the lubrication separated by the oil separator (11) is performed. Oil (A) oil return pipe (1
It is designed to be returned only to the inside of the dome (3) of the second compressor (2) of the above compressors (1) and (2) via 2). Further, the oil return pipe (12) has a capillary (1
0) is interposed, and the amount of oil returned to the dome (3) of the second compressor (2) is controlled by this capillary (10).

Further, in the both compressors (1) and (2), the operating capacity of the second compressor (2) is made smaller than the operating capacity of the first compressor (1) by the controller (16) as the operating capacity control means. The operating mode is set so that the internal pressure of the dome of the second compressor (2) to which the lubricating oil (A) from the oil separator (11) is returned is always higher than that of the first compressor (1). Controlled.

Therefore, in the above embodiment, when the refrigerant gas is discharged from the compressors (1) and (2) during the operation of the refrigeration system, the lubricating oil (A) in the refrigerant gas is separated by the oil separator (11). The lubricating oil (A) is returned to the inside of the dome (3) of the second compressor (2) via the oil return pipe (12).

At this time, the operation modes of both the compressors (1) and (2) are controlled by the controller (16) so that the dome internal pressure of the second compressor (2) is always higher than that of the first compressor (1). Therefore, the lubricating oil (A) in the domes (3) and (3) of both compressors (1) and (2) is always from the second compressor (2) side to the first compressor (1) side. Lubricating oil (A) in the second compressor (2) that has moved to the inside of the dome (3) of the first compressor (1) while moving through the oil equalizing pipe (7)
Is reduced by the amount of oil returned to the dome (3) of the second compressor (2) through the oil return pipe (12), and thus both compressors (1) , (2) The oil surface in (2) can be surely made uniform.

Further, the lubricating oil (A) separated by the oil separator (11)
Since the oil return destination is specified to the second compressor (2), it is not necessary to connect the oil return pipe (12) to the first compressor (1) side, and thus the refrigerant circuit and control circuit It can be simplified. Moreover, when the oil return destination is specified as described above, it is only necessary to provide the capillary (10) for controlling the oil return amount, and the oil return destination is the compressor (1).
Or, the switching valve etc. for selecting to (2) becomes unnecessary,
Furthermore, the device can be simplified.

(Effects of the Invention) As described above, according to the present invention, in the refrigerating apparatus in which two variable capacity compressors (1) and (2) are connected in parallel to one system refrigerant circuit, One compressor (1)
Alternatively, the operating capacities of both compressors (1) and (2) are controlled so that the dome internal pressure of (2) is always higher than that of the other compressor (2) or (1), and the dome internal pressure increases. Since the lubricating oil (A) from the oil separator (11) is returned only to the inside of the dome (3) of one of the compressors (1) or (2), both compressors (1) and (2) Lubricating oil (A)
Moves from the higher dome internal pressure to the lower dome internal pressure through the oil equalizing pipe (7), and even if the amount of oil in the compressor (1) or (2) with a high dome internal pressure decreases due to this movement, this decrease The returned oil amount is supplemented by the oil return, so that the oil amounts in both compressors (1) and (2) can be surely made uniform.

In addition, since oil can be reliably leveled between the compressors (1) and (2) in this manner, it is possible to use a small diameter oil equalizing pipe (7) and use a large diameter oil equalizing pipe. It is possible to prevent an increase in vibration of both compressors and a reduction in strength of the oil equalizing pipe. Furthermore, since both compressors (1) and (2) can be oil-equalized without the need for control parts such as a float type regulator and an oil level sensor, cost reduction and control reliability improvement are also achieved. Can be planned.

In addition, as described above, since the oil return pipe (12) needs to be connected to only one of the compressors (1) or (2), the refrigerant circuit and the control circuit can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a refrigerating apparatus according to an embodiment of the present invention. (1) ... 1st compressor, (2) ... 2nd compressor, (3) ... Dome, (7) ... Oil leveling pipe, (8) ... Suction pipe, (9) ... Discharge pipe, (11) ... Oil Separator, (12) ... Oil return pipe, (1
6) ... Controller (operating capacity control means), (A) ... Lubricating oil.

Claims (1)

[Claims] 1. Two variable capacity compressors (1), (2) for compressing a refrigerant gas sucked into a dome (3) by a suction pipe (8) and discharging it by a discharge pipe (9). In a refrigerating device connected in parallel to a single-system refrigerant circuit, the insides of the domes (3) and (3) of both compressors (1) and (2) are set to the operating oil level level of the lubricating oil (A). Oil pipe (7) communicating with each other, an oil separator (11) for separating lubricating oil (A) from the refrigerant gas discharged to the outside of the dome (3) by the discharge pipe (9), and this oil separator ( An oil return pipe (12) for returning the lubricating oil (A) separated in 11) only into the dome (3) of one of the compressors (1) and (2) , So that the internal pressure of the dome of one compressor (1 or 2) to which the lubricating oil (A) is returned is always higher than that of the other compressor (2 or 1) Both the compressor (1), refrigeration system, characterized by comprising a driving capacity control means for controlling the operating capacity of the (2) (16).