JPH0140234B2 - - Google Patents

Description

[Detailed description of the invention]

This invention is applicable to a plurality of refrigerant compressors connected in parallel with each other, regardless of the rotational direction of the first refrigerant compressor, or when one refrigerant compressor is operated on one side. The present invention relates to a parallel compression type refrigeration system that can maintain a normal oil level in a compressor even in such cases. FIG. 1 is a refrigerant piping diagram of a conventional parallel compression type refrigeration system and the present invention. First, the conventional parallel compression type refrigeration system will be described with reference to FIG. In FIG. 1, 1 and 2 are semi-hermetic first and second refrigerant compressors, respectively;
01 is a crankcase that constitutes the first and second refrigerant compressors 1 and 2. Both crankcases 1
The inside of 01, 201 is partitioned by partition walls 102, 202 into suction chambers 103, 203 that accommodate motor A, and oil reservoir chambers 104, 204 that accommodate compression element B. Pressure equalizing holes 10 are provided at predetermined positions in the partition walls 102 and 202.
5,205 are provided. This partition wall 102,
An oil level equalizing pressure hole is provided at a predetermined position of 202, and an oil level equalizing check valve 106, 20 is installed in this oil level equalizing hole.
6 is installed. These oil equalizing check valves 106, 206 are connected to the suction chamber 10.
The lubricating oil is allowed to flow only from the oil reservoir chambers 3,203 to the oil reservoir chambers 104,204. Moreover, 107 and 207 are oil splashers for lubricating the sliding parts, respectively. On the other hand, 3 is the suction chamber 103 of the first refrigerant compressor 1
The first gas suction pipe is connected to the suction pipe 5 which is connected to the evaporator (not shown) of the refrigeration cycle. Further, the second gas suction pipe 4 is connected to the suction chamber 203 of the second refrigerant compressor 2. This second gas suction pipe 4 branches from the upper part of the suction pipe 5. Furthermore, 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. ) is connected in parallel to the high pressure pipe 8 connected to the high pressure pipe 8. The oil equalizing hole 108 of the oil reservoir chamber 104 of the first refrigerant compressor 1 and the oil equalizing hole 208 of the oil reservoir chamber 204 of the second refrigerant compressor 2 are connected to each other by an oil equalizing pipe 9, A check valve 10 is provided in the middle of this oil equalizing pipe 9. This check valve 10 is for allowing flow only from the first refrigerant compressor 1 to the second refrigerant compressor 2. Next, the operation of the conventional parallel compression type refrigeration system configured as described above will be explained. 1st, 2nd
When the refrigerant compressors 1 and 2 are operated in parallel and when the first and second refrigerant compressors 1 and 2 are operated on one side, most of the lubricating oil in the refrigeration cycle is transferred to the first lubricant due to inertia due to the flow velocity of oil particles. The gas passes through the gas suction pipe 3 and flows into the first refrigerant compressor 1. The first gas suction pipe 3 and the second gas suction pipe 4 have different flow path resistances depending on the pipe thickness and length, so the flow path resistance of the second gas suction pipe 4 is always greater. Therefore, the suction difference 103, 20 between the first refrigerant compressor 1 and the second refrigerant compressor 2 is
The oil reservoir chambers 104 and 204 in 3 have the following pressure relationships, respectively. <When operating two units, when operating the second refrigerant compressor> First suction chamber 103 > first oil reservoir chamber 104 > second oil reservoir chamber 204 > second suction chamber 203 This pressure relationship Therefore, the lubricating oil flowing into the suction chamber 103 of the first refrigerant compressor 1 passes through the oil equalizing check valve 106, the oil reservoir chamber 104, the oil equalizing hole 108, and the oil equalizing pipe 9, and then flows into the second refrigerant compressor. 2 oil equalizing hole 20
8 into the oil reservoir chamber 204 of the second refrigerant compressor 2. The oil reservoir chamber 204 and suction chamber 203 of the second refrigerant compressor 2 are shut off by the oil equalizing check valve 206, and the lubricating oil in the oil reservoir chamber 204 does not move. In such a pressure equalizing oil mechanism, the lubrication method for the first refrigerant compressor 1 is an oil splasher 107.
In the case of the system shown in FIG. 3 (clockwise rotation) and FIG. )
When the refrigerant is splashed in the direction of the oil equalizing hole 108, the first and second refrigerant compressors 1,
Due to the pressure difference between the two, the lubricating oil in the oil sump chamber 104 of the first refrigerant compressor 1 is transferred to the oil sump chamber 2 of the second refrigerant compressor 1.
04, the oil sump chamber 10 of the first refrigerant compressor 1
The oil level at No. 4 decreases, and the lubricating oil decreases until it is balanced at the lower limit of the oil equalizing hole 108. FIG. 2 is a front view of the refrigerant piping shown in FIG. 1, showing the state of the oil level in the first and second refrigerant compressors 1 and 2, which is indicated by the broken line 1A in the first refrigerant compressor 1. The oil level is the oil level at balance. Next, when one of the first refrigerant compressors 1 is operated,
A check valve 10 in the oil equalizing pipe 9 allows the first refrigerant compressor 1 to operate independently. As described above, the oil level height differs depending on the direction of splashing of the first refrigerant compressor 1 (direction of rotation of the motor), and especially when splashing in the direction of the oil equalizing hole 108, The oil level in the oil reservoir chamber 104 of the first refrigerant compressor 2 may become low, resulting in a lack of oil, or if oil is determined to be insufficient during inspection, oil may be added, causing oil compression in the second refrigerant compressor 2. Further, even if the connection on the power supply side is changed during electrical work or the like and the rotation of the first refrigerant compressor 1 changes from normal to reverse, protection cannot be achieved. This invention was made to eliminate the above-mentioned conventional drawbacks, and detects whether the power supply is in the normal phase or the negative phase, and stops only the second refrigerant compressor and operates only the first refrigerant compressor. In this way, the oil level in each refrigerant compressor can be maintained at an appropriate level, and even when the phase is reversed due to electrical work, etc., the temperature rise of the cooled object can be prevented by stopping two refrigerant compressors. It is an object of the present invention to provide a parallel compression type refrigeration system that can be made smaller. Embodiments of the parallel compression type refrigeration system of the present invention will be described below with reference to the drawings. The refrigerant piping in this invention is the same as that shown in FIG. 1, and its explanation will be omitted. The electric circuit for controlling the operation and stopping of the second refrigerant compressor will be explained with reference to FIG. In FIG. 5, A-1 is the motor of the first refrigerant compressor 1, and A-2 is the motor of the second refrigerant compressor 2. These motors A-1 and A-2 are connected to three motors via contacts 21 and 22 of a magnetic contactor, respectively.
Connected to R phase, S phase, and T phase of phase AC power supply. A negative phase preventer 25 is connected to the S phase and T phase of this three-phase AC power source, and this negative phase preventer 25 detects the positive phase and negative phase of the power source. Also,
The anti-phase preventer 25 is connected to the R phase via a relay coil 26, and the anti-phase preventer 25 energizes the coil 26 only when the power supply is in the positive phase. Further, the line L1 is connected to the R phase via a contact C1, and the line L2 is connected to the S phase via a contact C2. A series circuit of the control signal circuit 28 and the coil 23 of the electromagnetic contactor is connected between the lines L1 and L2. The control signal circuit 28 is a circuit for controlling the first refrigerant compressor 1. Between lines L1 and L2, contact 2 of the electromagnetic contactor
7 (normally open contact), a control circuit 29, and a series circuit of the coil 24 of the electromagnetic contactor are connected, and the control signal circuit 29 is a circuit for controlling the second refrigerant compressor 2. Between lines L1 and L2, contact 3 of the above relay is connected.
0 (normally closed contact) and an indicator lamp 31 are connected in series. Next, the operation of the parallel compression type refrigeration system of the present invention configured as described above will be explained. When the connection of the three-phase AC power supply is in the positive phase, the first refrigerant compressor 1
It is assumed that the lubricating oil is splashed on the side where the rotation direction of the motor A-1 is opposite to the oil equalizing hole 108. Now, assuming that the three-phase AC power supply is in the positive phase, the negative phase preventer 25 energizes the coil 26 of the relay,
This coil 26 is excited. As a result, the contact 27 of the relay is closed and the coil 2 of the electromagnetic contactor is closed.
4 is excited. This excitation of the coil 24 closes the contact 22 and energizes the motor A-2 of the second refrigerant compressor 2. Then, the motor A of the first refrigerant compressor 1
Since the rotation direction of -1 is the positive phase of the three-phase AC power supply, the rotation direction of the oil splasher 107 is opposite to the oil equalizing hole 108, and therefore the lubricating oil in the oil reservoir chamber 104 decreases. Never. Next, when the reverse phase connection is made, the reverse phase preventer 25
As a result, the coil 26 of the relay is no longer energized,
Its contact 27 is opened. As a result, the coil 24 of the electromagnetic contactor is deenergized, and the contact 22 of the second refrigerant compressor 2 to the motor A-2 is opened.
The rotation of this motor A-2 is stopped, and the operation of the second refrigerant compressor 2 is stopped. However, the operation of the first refrigerant compressor 1 is carried out,
As explained in the description of the prior art, one of the first refrigerant compressors 1 operates independently and can hold lubricating oil regardless of the rotation direction. At this time, the relay contacts 30 are closed, and the indicator lamp 31 is lit to indicate that the phase is reversed. As described above, according to the parallel compression type refrigeration system of the present invention, the normal phase and negative phase of the power source are detected by the negative phase preventer, and when the power source is in the positive phase, the first and second refrigerant compressors are activated. If the power supply is in reverse phase, the operation of the second refrigerant compressor is stopped, and only the first refrigerant compressor is operated, and the rotation direction of the first refrigerant compressor is Since the oil level of the lubricating oil is prevented from dropping without any problem, the drawbacks caused by a drop in the oil level of the lubricating oil can be eliminated. Also, even when the phase is reversed due to electrical work, etc.,
Since only the first refrigerant compressor is operated, the temperature of the object to be cooled does not rise due to stopping the operation of the two refrigerant compressors, and damage to the product can be prevented. It also has the advantage of

[Brief explanation of drawings]

Fig. 1 is a refrigerant piping diagram of the conventional parallel compression type refrigerator and the present invention, Fig. 2 is a front view of the refrigerant piping diagram of the parallel compression type refrigerator of Fig. 1, and Figs.
The figures are diagrams for explaining the oil level height according to the rotational direction of the first refrigerant compressor in a conventional parallel compression refrigeration system, and Figure 5 shows an embodiment of the parallel compression refrigeration system of the present invention. It is an electrical circuit diagram. 1...First refrigerant compressor, 2...Second refrigerant compressor, 104,204...Oil sump chamber, 106,20
6... Oil equalizing check valve, 107, 207... Oil splasher, 3... First gas suction pipe, 4... Second gas suction pipe, 9... Oil equalizing pipe, 10... Non-return Valve, 21, 22... Contact of electromagnetic contactor, 23, 2
4... Magnetic contactor coil, 25... Reverse phase preventer, 26... Relay coil, 27, 30... Relay contact, 31... Display lamp. Note that the symbols in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An oil equalizing check valve that allows oil to flow only from the suction chamber side to the oil reservoir chamber side is provided at a predetermined position on the partition wall that divides the inside of the crankcase into the suction chamber side and the oil reservoir chamber side, and an oil splatter is provided. first and second refrigerant compressors having a shear; means for connecting the first and second refrigerant compressors in parallel with each other;
a first gas suction pipe connected to the suction chamber of the refrigerant compressor and to the lower part of the suction pipe of the refrigeration cycle; a suction pipe of the refrigeration cycle connected to the suction chamber of the second refrigerant compressor; A second gas suction pipe connected to the upper part of the refrigerant compressor connects the oil reservoir chambers of the first and second refrigerant compressors, and connects only the first refrigerant compressor to the second refrigerant compressor in the middle. An oil equalizing pipe having a check valve that allows the flow of lubricating oil, a reverse phase preventer that detects the normal phase and reverse phase of the power supply supplied to the first refrigerant compressor, and lubricating oil for the first refrigerant compressor. During the positive phase of the rotation in which the direction of splashing is opposite to the connection port of the oil equalizing pipe, the reverse phase preventer activates the second refrigerant compressor to enable operation, and the reverse phase of the power source is activated. Sometimes this second
A parallel compression refrigeration system comprising means for stopping the operation of a refrigerant compressor.