JPH0140233B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling the oil level of a compressor, either when refrigerant compressors connected in parallel with each other are operated in parallel, or when one of the refrigerant compressors is operated on one side. This invention relates to an improvement of a parallel compression type refrigeration system that maintains normal conditions.

Conventionally, there has been a device of this type as shown in FIG. In the figure, 1 and 2 are semi-hermetic first and second refrigerant compressors, and 101 and 201 are the first and second refrigerant compressors.
and a crankcase that constitutes the second refrigerant compressor 1, 2. Inside both crankcases 101, 201 are suction chambers 103, 203 that house motors A1, A2 by partition walls 102, 202, and compression elements B1, B.
It is partitioned into oil reservoir chambers 104 and 204 for storing oil. 105, 205 are the partition walls 102, 20
2 pressure equalization holes provided at predetermined positions, 106, 20
Reference numeral 6 denotes an oil equalizing check valve installed in an oil level equalizing hole provided at a predetermined position in the partition walls 102, 202, and the oil equalizing check valve 106, 206 is connected to the suction chamber 10.
The lubricating oil is allowed to flow only from the oil reservoir chambers 104, 204 to the oil reservoir chambers 104, 204. 107, 207 is a crankshaft 10 that drives compression elements B1, B2 by motors A1, B1.
8, 208, and splashes the lubricating oil at the inner bottom of the oil reservoir chambers 104, 204 onto the sliding parts such as bearings of the compression elements B1, B2; 3 is the first refrigerant compressor 1; The first gas suction pipe is connected to the suction chamber 103 of the refrigeration cycle, and is connected to the lower part of the suction pipe 5 connected to the evaporator (not shown) of the refrigeration cycle. 4 is a suction chamber 203 of the second refrigerant compressor 2;
a second gas suction pipe connected to the suction pipe 5;
The compressors 1 and 2 are connected in parallel through a first gas suction pipe 4 which branches out from the upper part of the gas suction pipe 4 . Further, the connection relationship between the first and second gas suction pipes 3 and 4 and the suction pipe 5 constitutes a separation means 501 that separates the refrigerant gas in the suction pipe 5 into gas and lubricating oil. 6 is a gas discharge pipe of the first refrigerant compressor 1, 7 is a gas discharge pipe of the second refrigerant compressor 2, and both gas discharge pipes 6 and 7 are connected to a condenser (not shown) of the refrigeration cycle. The high pressure pipe 8 is connected in series to the high pressure pipe 8. Reference numeral 9 denotes an oil equalizing pipe that interconnects the oil equalizing hole 109 of the oil reservoir chamber 104 of the first refrigerant compressor 1 and the oil equalizing hole 209 of the pressure reservoir chamber 204 of the second refrigerant compressor 2; is a check valve that is provided in the middle of the oil equalizing pipe 9 and allows flow only from the first compressor 1 to the second compressor 2.

Next, the operation will be explained. When both compressors 1 and 2 are in operation, the relationship between the operating pressures of the first compressor 1 and the second compressor 2 is determined by the difference in piping resistance between the suction pipes 3 and 4 of both compressors 1 and 2. is (suction chamber 103 pressure of first compressor 1)-(suction chamber 203 pressure of second compressor 2)=approximately 100 to 400 mmAg. Further, normally, oil containing about 0.5% of the refrigerant circulation amount returns to the compressors 1 and 2 together with the refrigerant gas that has evaporated inside the suction pipe 5 of the refrigerant cycle. At this time, the refrigerant gas is separated into lubricating oil and gas by the separating means 501, and most of this lubricating oil flows into the suction pipe 3 of the first compressor 1 under the influence of gravity, and the lubricating oil flows into the suction pipe 3 of the first compressor 1.
It passes through the suction chamber 103 of the compressor 1 and the oil equalizing check valve 106, and is supplied to the oil reservoir chamber 104. The pressure of the lubricating oil is equalized in the oil reservoir chambers 104, 204 of both compressors 1, 2 by the pressure equalizing oil pipe 9, and there is a differential pressure between the suction chambers 103, 203 of both compressors 1, 2 as described above. Therefore, in order to flow together with gas from the oil reservoir chamber 104 of the first compressor 1 to the oil reservoir chamber 204 of the second compressor 2, the oil of the second compressor 2 passes through the oil equalizing pipe 9 and the check valve 10. It is supplied to the reservoir chamber 204 and normally performs the lubricating function.

Next, when only the first compressor 1 is operated, the refrigerant gas and lubricating oil flow from the suction pipe 5 into the suction chamber 103 via the suction pipe 3 of the first compressor 1. During this time, the pressure in the suction pipe 103 of the first compressor 1 decreases by about 400 mmAg due to pressure loss in the pipe. On the other hand, since the oil equalizing pipe 9 is provided with a check valve 10 that operates at approximately 100 mmAg,
Gas is prevented from flowing into the oil reservoir chamber 104 of the compressor 1, and the pressure in the oil reservoir chamber 104 is maintained at approximately the same level as the suction chamber 103 by the action of the pressure equalization hole 105.
Therefore, the lubricating oil returned to the suction chamber 103 is transferred to the oil reservoir chamber 1.
04, and even if the first compressor 1 is operated continuously, the oil level can be stabilized.

Next, when only the second compressor 2 is operated, the refrigerant gas is transferred from the suction pipe 5 to the suction pipe 4 of the second compressor 2.
It flows into the suction chamber 203. During this time, the pressure decreases by approximately 600mmAg due to pressure loss in the piping. Further, the pressure in the oil reservoir chamber 204 is also reduced by the action of the pressure equalizing hole 205. On the other hand, lubricating oil flows from the suction pipe 5 into the oil reservoir chamber 104 via the suction pipe 3 of the first compressor 1, the suction chamber 103, and the oil equalizing check valve 106.
Because the compressor 1 is not operating, the pressure loss in the suction pipe 3 is extremely small, so the pressure P ₁₀₄ in the oil reservoir chamber 104 of the first compressor 1 and the oil reservoir chamber 20 of the second compressor 2 are the same.
The relationship between pressure P ₂₀₄ of No. 4 is P ₁₀₄ > P ₂₀₄ , and a part of the oil accumulated in the oil reservoir chamber 104 of the first compressor 1 is supplied to the reservoir chamber 204 of the second compressor 2 due to the pressure difference. and operate normally.

However, as shown in FIG. 2, the oil equalizing holes 109 and 209 are normally located on the side of the crank bearing support of both compressors 1 and 2, and as the oil splasher 107 rotates, the oil level rises. If there is an oil equalizing hole 109 on the side of the compressor 1 on the side where the compressor 1 are oil equalizing hole 109, oil equalizing pipe 9, check valve 10,
A large amount of oil passes through the oil equalization hole 209 of the second compressor 2 and moves to the oil reservoir chamber 204 of the second compressor 2, which tends to cause the oil level of the compressor during operation to become unbalanced, making maintenance difficult. There were drawbacks such as difficulty in checking the oil level position through the oil window and maintenance work. Also,
As the oil level of the first compressor 1 decreases, lubricating oil is not supplied to the sliding parts of the compressor, and the first
The second compressor 1 may seize up, the oil level in the second compressor 2 may rise abnormally, the refrigeration capacity may decrease due to excessive oil coming up from the compressor during operation, and there is a risk of damage to the valve part due to oil compression. It was hot.

This invention was made in order to eliminate the above-mentioned conventional drawbacks, and one embodiment of the invention will be described below.

The configuration of the refrigeration system is the same as that of the conventional one, so the explanation thereof will be omitted and will be explained based on the electric circuit diagram shown in FIG. 3.

In the figure, A1 is the motor of the first compressor 1, and A2 is the motor of the second compressor 2, which are connected to the three-phase power supply R, S, T together with the first one.
21 and 22 are contacts of the first and second electromagnetic switches that control the operation of the first and second motors A1 and A2;
3 and 24 are coils, which are connected in parallel in the operating circuit. 25 is a positive and negative phase detector inserted into the three-phase power supplies R, S, and T to detect the positive and negative phases of the three-phase power supplies R, S, and T. It is inserted into the R phase only when the phase is positive. This energizes the relay 26. 2
7 and 28 are the contacts of the first and second electromagnetic contactors for switching the phases of the three-phase power supply R, S, and T, and contact 27
is inserted into the R and S phases of the three-phase power supply, and the contact 28 is inserted into the connection circuit between the R and S phases and the connection circuit between the S and R phases of the three-phase power supply. 29 and 30 are coils of the first and second electromagnetic contactors, which are connected in parallel in the operating circuit. 31 is an a contact of the relay 26, which is connected in series to the coil 29 of the first electromagnetic contactor. 32 is a b contact of the relay 26, which is connected in series to the coil 30 of the second electromagnetic contactor.
Reference numerals 33 and 34 designate controllers such as a protection device for the refrigeration cycle and a thermostat that responds to the magnitude of the load, which are connected in series to the coils 23 and 24 of the first and second electromagnetic contactors. SW is the operation switch.

Next, the operation will be explained.

When the first compressor 1 is connected in the normal phase, when the operation switch SW is turned on, the positive and negative phase detector 25 detects this and the relay 26 is energized and the a contact 31 of the relay 26 is closed. , the coil 29 of the first electromagnetic contactor is energized, the first contact 27 of the electromagnetic contactor is closed, and power is supplied to the motors A1 and A2 of the first and second compressors 1 and 2. become a state. At this time, the coil 3 of the second electromagnetic contactor
0, since the b contact 32 of the relay 26 is open, no current is applied, and the contact 28 of the electromagnetic contactor is in an open state. Therefore, the first and second compressors 1 and 2
Oil splasher 1 is driven by motors A1 and A2.
07,207 is in the direction of the solid arrow in FIG. 4, that is, the oil splasher 108 of the first compressor 1.
In the first compressor 1, the oil splashing direction is rotated in the opposite direction to the oil equalizing hole 109, which is the connection part of the oil equalizing pipe 9, and the oil level on the oil equalizing hole 109 side is relatively lowered. The lubricating oil returned to the oil reservoir chamber 104 does not move to the second compressor 2 side more than necessary.

On the other hand, in the case of a reverse phase connection in which any two of the R, S, and T phases of a three-phase power supply are connected interchangeably during equipment installation or service, the positive and negative phase detector 2
5 detects this and does not energize the relay 26. Therefore, the relay 26a contact 31 is in an open state,
The b contact 32 is in a closed state. Therefore, the coil 29 of the first electromagnetic contactor is not energized and its contact 27
is open, the coil 30 of the second magnetic contactor is energized, and its contact 28 is closed, and the three-phase power supply R, S,
The R phase on the primary side and the S phase on the secondary side of T are also 1
The S phase on the next side and the R phase on the secondary side are exchanged. Therefore, motors A1 and A of both compressors 1 and 2
2 is a positive phase connection, and the oil splasher 107 is moved by the motor A1 to the oil equalizing hole 1 as described above.
Rotate in the opposite direction to 08 so as to spray oil.

As described above, in the present invention, in which oil is returned to the second compressor via the first compressor, when the wiring of the motor of the first compressor is incorrectly connected during installation etc., the reverse phase connection is caused. However, the direction of oil splashing by the first oil splasher is opposite to the connection side of the oil equalizing pipe that connects both compressors.
Since the circuit that rotates the motor of the compressor is built in, the lubricating oil level of the compressor can be maintained at a good level whether the first and second compressors are operated simultaneously or only one compressor is operated. This makes it possible to improve the reliability of the compressor and to facilitate the compressor motor wiring work during installation.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a parallel compression refrigeration system, Fig. 2 is an explanatory diagram of the operation of the conventional apparatus, Fig. 3 is an electric circuit diagram showing an embodiment of the present invention, and Fig. 4 is an explanation of the operation of the inventive apparatus. It is a diagram. In the figure, 1 and 2 are the first and second compressors, 10
1,201 is a crankcase, 102,202 is a partition wall, 103,203 is a suction chamber, 104,20
4 is an oil reservoir chamber, 105, 205 is a pressure equalization hole, 106,
206 is an oil equalizing check valve, 107 and 207 are oil splashers, 3 and 4 are first and second suction pipes,
5 is a suction pipe of the refrigeration cycle, 9 is an oil equalizing pipe, 10 is a check valve, A1, A2 are motors, B1, B2 are compression elements, 25 is a forward/reverse phase detector, 26 is a relay, 2
9 and 30 are first and second electromagnetic contactors.
In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A check valve that allows an oil flow path only from the suction chamber side to the oil reservoir chamber side is installed in the partition wall that divides the inside of the crankcase into the suction chamber side and the oil reservoir chamber side, and a check valve is installed in the suction chamber and connected to a three-phase power source. A connected motor and a compression element provided in the oil sump chamber and driven by the motor via a crankshaft are driven together with the crankshaft to supply lubricating oil in the oil sump chamber to the sliding parts of the compression element. a first and second compressor having a splashing oil splasher, a first suction pipe connecting the suction chamber of the first compressor and a suction pipe of a refrigeration cycle, and the second compressor; A second suction pipe connects the suction chamber of the refrigeration cycle to the upper part of the suction pipe of the refrigeration cycle, connects both the compressors in parallel together with the first suction pipe, and connects the oil sump chambers of the two compressors. An oil equalizing pipe with a check valve that allows flow only from the first compressor to the second compressor is provided, and the lubricating oil in the refrigeration cycle is returned to the second compressor via the first compressor. A positive phase connection in which the motor of the first compressor rotates such that the direction of oil splashing by the oil pressure of the first compressor is opposite to the connection side of the oil equalizing pipe. and a forward/reverse phase detector that detects a reverse phase connection that rotates in the opposite direction. When this forward/reverse phase detector detects a positive phase connection, the motor of the first compressor is operated as it is and the reverse phase is turned on. A parallel compression type refrigeration system comprising: a control circuit that switches two phases of the three-phase power supply when phase connection is detected, and operates the motor of the first compressor in positive phase connection.