JPH0222873B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an air conditioner equipped with a plurality of compressors.

[Conventional technology]

A conventional device of this type is shown in FIG. FIG. 1 shows an example in which two compressors are used. 1a and 1b are compressors, 2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is a throttle device, 5 is a connection pipe, 6 is an indoor heat exchanger, 7 is a connection pipe, 8 is an accumulator, and 9 is a This is an oil equalizing pipe that connects the closed containers of the compressors 1a and 1b. Depending on the air conditioning load, there are cases in which only one compressor 1a and 1b is operated, and cases in which two compressors are operated in parallel. In addition, the oil equalizing pipe 9 has the function of preventing the refrigerating machine oil inside the compressor from being concentrated on one side of the compressor. In order to prevent this from accumulating, a part of the high-temperature refrigerant that is in operation is passed through the closed container of the stopped compressor via the oil equalizing pipe 9, and the temperature of the stopped compressor is adjusted. By keeping the compressor at the same temperature as the
It has a function to prevent refrigerant from accumulating inside the compressor container when the compressor is stopped, but when one compressor is operated, the refrigerating machine oil of the operating compressor may leak inside the compressor container when the compressor is stopped. The oil gradually accumulates in the compressor, causing a shortage of refrigeration oil in the operating compressor.
Another disadvantage is that refrigerating machine oil accumulates in the cylinder through the discharge valve of the stopped compressor and the oil supply pipe to the cylinder, causing an oil hammer when starting up and causing the compressor to malfunction.

Furthermore, when the compressors 1a and 1b are started, the refrigerant that has been trapped in the refrigerating machine oil forms and a large amount of refrigerating machine oil is discharged, and even during continuous operation, the refrigerating machine oil is constantly discharged, and the discharged refrigerating machine oil is The refrigerating machine oil circulates through the refrigeration cycle and returns to the suction side of the compressors 1a and 1b, but there are differences in the amount of refrigerating machine oil discharged due to the forming at the time of starting each compressor, and the amount of refrigerating machine oil returning to the suction side. Due to the difference in the amount, the compressor may have too much or too little refrigerating machine oil.
The problem was that the compressor could seize up due to an insufficient amount of oil. Furthermore, if the connecting pipes 5 and 7 are particularly long, it will take time for the discharged refrigerating machine oil to circulate and return, and when one compressor is operated, the amount of refrigerant circulating will decrease, causing the refrigerant to flow inside the pipes. Since the refrigerant speed decreases, the return of the refrigerating machine oil becomes difficult, which also causes defects in the compressors 1a and 1b.

Furthermore, when the air conditioner is stopped, the refrigerant that had accumulated in the connecting pipes 5 and 7 returns to the discharge pipe and suction pipe of the compressor due to its own weight, filling the discharge port and suction port of the compressor.
This had the disadvantage that the valve (not shown) was damaged when the compressor was started.

[Summary of the invention]

This invention was made with the aim of eliminating the above-mentioned drawbacks of the conventional technology, and includes a check valve and an oil separator between the discharge side of each compressor and the four-way valve. A solenoid valve is installed from the oil separator, and a bypass path is provided from the oil separator to the accumulator via the solenoid valve, and the refrigerating machine oil is returned to the accumulator. By returning part of the gas discharged during defrosting to the accumulator, the defrosting capacity can be significantly increased by increasing the low pressure and sending a highly concentrated refrigerant with a small specific volume to the compressor. Defrosting can be completed in a short time, and when one compressor arranged in parallel is operated, since there is no oil equalizing pipe 9, the refrigerating machine oil of the operating compressor passes through the oil equalizing pipe and stops. By installing a check valve on the discharge side of the compressor when it is stopped, refrigerating machine oil and Refrigerant does not accumulate, and by installing a check valve between the accumulator and the suction side of each compressor, it is possible to prevent refrigerating machine oil from flowing out from the suction side of the compressor when it is stopped.
This prevents valve damage and seizure defects when starting the compressor. In addition, even if the refrigerant and refrigeration machine oil that had accumulated in the discharge piping system return to the discharge side of the compressors 1a and 1a due to their own weight and pressure when the air conditioner is stopped, they will be accumulated in the oil separator and The check valve prevents the refrigerant and refrigeration oil accumulated in the suction piping system from entering the compressor discharge side, and even if the refrigerant and refrigeration machine oil that have accumulated in the suction piping system return to the suction side of the compressor due to their own weight and pressure, the It is stored in the rotor and can be prevented from entering the inside of the compressor suction side by a check valve.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. In FIG. 2, the same or corresponding parts as in FIG. 1 are designated by the same reference numerals.
In Fig. 2, 10 is an oil separator, 11 is a bypass path, 12 is a solenoid valve, 13a and 13b are check valves installed on the compressor discharge side, and 14a and 14b are check valves installed on the compressor suction side. It is. That is, the second
As shown in the figure, check valves 13a, 13 are installed between the discharge side of each compressor 1a, 1b and the four-way valve 2.
(b) A check valve is arranged in the order of the oil separator 10, and a bypass path 11 is provided from the oil separator 10 to the accumulator 8 via a solenoid valve 12.
Check valves 13a, 13b are provided between the discharge side of each compressor 1a, 1b and the oil separator 10, and are closed when the pressures before and after are the same. Further, check valves 14a and 14b are provided between the accumulator 8 and the suction side of each of the compressors 1a and 1b, and are closed when the pressures before and after are the same.

Further, the electric circuit shown in FIG. 3 includes a stop switch 15,
Operation switch 16, self-holding relay 17 and 1
9. A timer 20 for forcing the compressors 1a and 1b to operate for a predetermined period of time at initial startup, and an oil separator 1
Solenoid valve coil 21 for opening and closing bypass valve 12 from 0 to accumulator 9, two compressors 1
a, a compressor contactor 22 for operating 1b,
23, a two-stage thermostat 24, a heating/cooling switch 25, and the like.

The operation of the present invention will be explained in the above configuration.

In Fig. 2, solid arrows indicate the flow of refrigerant during cooling and defrosting operations, dashed arrows indicate the flow of refrigerant during heating, and dashed-dotted lines indicate the flow of refrigerant and refrigerating machine oil in the bypass path. It is.

During cooling, the high-temperature, high-pressure refrigerant and refrigerating machine oil discharged from the compressors 1a and 1b arranged in parallel pass through check valves 13a and 13b, respectively, and enter the oil separator 10 from above, where the refrigerating machine oil is separated. The separated oil is collected at the bottom of the oil separator 10, and the refrigerant separated from the refrigeration oil is collected in the oil separator 1.
It exits from the upper part of the 0, reaches the 4-way valve 2 and the outdoor heat exchanger 3, exchanges heat with the heat exchanger 3 to become a high temperature and high pressure liquid, is then depressurized by the expansion device 4, and passes through the connecting pipe 5. After that, it is evaporated in the indoor heat exchanger 6, and returns to the compressors 1a and 1b connected in parallel again through the connecting pipe 7, the four-way valve 2 acumulator 8, and the check valves 14a and 14b. Note that during this operation, the solenoid valve 12 located in the middle of the bypass path 11 is closed, but if oil accumulates in the oil separator 10, the oil separator 10
The solenoid valve 12 is opened by the oil sump detection output signal of the oil sump detector (not shown) inside the oil separator 10, and the refrigerating machine oil accumulated at the bottom of the oil separator 10 is passed through the solenoid valve 12 and the bypass path 11. The refrigerating machine oil is returned to the accumulator 8, and returns to the compressors 1a and 1b together with the low-temperature, low-pressure gas returned from the indoor heat exchanger 6. The refrigerating machine oil circulation circuit is different from that of the conventional system shown in Fig. 1. It is shortened to a large width. As is clear from the refrigerant flow indicated by the dotted arrows during the heating operation, the oil circulation circuit is similar to that during the cooling operation.

Therefore, by opening the solenoid valve 12 when the compressors 1a and 1b are started and closing it after a predetermined period of time (for example, 5 minutes), the refrigerant that has been trapped in the refrigerating machine oil when the compressors are stopped will form when the compressors are started, and the normal Compared to continuous operation, even if a large amount of refrigerating machine oil is discharged from the compressors 1a and 1b, only the refrigerating machine oil is separated by the oil separator and is opened via the bypass circuit 11 without circulating through the refrigerant circuit. The refrigerating machine oil is returned to the accumulator 8 through the solenoid valve 12, and returns to the compressors 1a and 1b together with the low-pressure gas, making it possible to compensate for the shortage of refrigerating machine oil in a short time.

In addition, even when the amount of refrigerating machine oil in the compressors 1a and 1b connected in parallel becomes unbalanced, the compressor with more refrigerating machine oil discharges a large amount of refrigerating machine oil, and the compressor with less refrigerating machine oil discharges a large amount of refrigerating machine oil. Due to the short circulation circuit of the refrigerator, the compressor's own adjustment function, which has a small amount, can function sufficiently, making it possible to eliminate imbalances in a short time.

Also, for a certain period of time (e.g. 5 minutes) after sleep startup.
By forcibly operating the two compressors 1a and 1b at the same time, the refrigerating machine oil that is discharged in large quantities due to sleep startup is forcibly recovered, and the two compressors are started at the same time and operated for a certain period of time. This makes it possible to drive out the refrigerant trapped in the refrigerating machine oil and actively create a state in which the amount of refrigerating machine oil is balanced.

Furthermore, even if the distance between the indoor unit and the outdoor unit is large, that is, the connection pipes 5 and 7 are long, the refrigerating machine oil circulation circuit will not be affected by the length of the connection pipes 5 and 7. Compressors 1a and 1b
There will be no refrigeration oil shortage.

In addition, when one compressor is in operation, the amount of refrigerant circulated is greatly reduced, and even when the amount becomes small, that is, the speed of refrigerant moving in the refrigerant piping is reduced, the circuit where the refrigerating machine oil circulates, that is, the bypass Since the length of the circuit is constant and short, there is no possibility of insufficient return of refrigerating machine oil.

In the air conditioner configured as shown in FIG. 3, when the operation switch 16 is turned on, the auxiliary relay 117 is energized and self-held by the a contact 17a of the relay 17. At this time, if even one of the contacts of the two-stage thermostat 24 is closed, the compressor contactors 22 and 23 are energized and one or both of the compressors 1a and 1b starts operating. 22 a contacts 22 at the same time
By closing any of the A contacts 23a, the timer 20 is energized, and the solenoid valve coil 21 is energized via the timer contact 20a, and the bypass valve 12 is opened to return oil from the oil separator 10 to the accumulator 9. will be carried out. On the other hand, the auxiliary relay 218 is energized, and the 18 a contact 18a is closed, regardless of whether the 2-stage thermostat 24 is on or off, both the compressor contactors 22 and 23 are energized, and the compressor 1
Perform forced operation on both a and 1b. After a predetermined time, the timer contact 20a is reversed by the timer 20, demagnetizing the solenoid valve coil 21 and the auxiliary relay 218, and simultaneously energizing the auxiliary relay 319.
The timer 20 is self-maintained by the a contact of the timer 20, and thereafter becomes ineffective unless the stop switch 15 is turned off.
In addition, the bypass valve 12 is closed by demagnetizing the solenoid valve coil 21, and the auxiliary relay 218 is demagnetized and the a contact 18a of the auxiliary relay 18 is opened, so that the compressor 2 is closed.
The forced operation of two units 2 and 23 is canceled and the two-stage thermostat 24 is enabled.

〔Effect of the invention〕

As explained above, in this invention, when the compressor is initially started and when it is stopped, the refrigerant lying in the refrigerant oil forms when the compressor starts, and a larger amount of refrigerant oil is discharged from the compressor than in normal continuous operation. However, by opening the electromagnetic valve 12 for a predetermined period of time, the refrigerating machine oil separated by the oil separator returns to the accumulator 8 via the bypass path 11, and is returned to the compressor together with the low-pressure gas. By forcedly operating the compressors 1a and 1b at the same time for the same time as the valve 12, the refrigerating machine oil discharged in large quantities due to sleep startup is forcibly recovered, and by starting both at the same time and operating for a certain period of time. The refrigerant trapped in the refrigerating machine oil can also be expelled and the amount of refrigerating machine oil can be balanced, which has the effect of preventing compressor failures due to oil shortage.

[Brief explanation of drawings]

FIG. 1 is a refrigerant system diagram showing a conventional example, FIG. 2 is a refrigerant system diagram of an embodiment of the present invention, and FIG. 3 is a control circuit diagram of an embodiment of the invention. In the figure, 1a and 1b are plural compressors, 2 is a four-way valve, 3 is an outdoor coil, 4 is a throttle device, 5 and 7 are connecting pipes, 6 is an indoor coil, 8 is an accumulator, 9 is an oil equalizing pipe, 10 is an oil separator, 11 is a bypass path, 12 is a bypass valve, 13a, 13b are discharge check valves, 14a, 14b are suction check valves, 15
is a stop switch, 16 is a run switch, 17 is auxiliary relay 1, 17a is a contact of auxiliary relay 1, 1
Reference numeral 8 indicates an auxiliary relay 2 that short-circuits the temperature controller 24 in order to forcefully operate the compressors 1a and 1b, 18a indicates the a contact of the auxiliary relay 2, and 19 indicates an auxiliary relay 3 that disables the timer 20 except for initial startup. The a contact of the auxiliary relay 3, 20a is the contact of the timer 20, 2
1 is a solenoid valve coil for opening and closing the bypass valve 12; 22 and 23 are compressor contactors; 22a and 23;
A indicates the a contact point of the compressor contactor, and 25 indicates the cooling/heating changeover switch. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In an air conditioner with a circulation cycle in which multiple compressors connected in parallel, a four-way valve, an outdoor heat exchanger, a throttling device, an indoor heat exchanger, and an accumulator are connected in a ring, the above-mentioned An oil separator is provided between the discharge side of the compressor and the four-way valve, and a bypass path is provided from the oil separator to the accumulator via a solenoid valve, and the plurality of compressors are operated simultaneously for a predetermined period of time after startup. An air conditioner, further comprising a control device having means for opening the solenoid valve when the compressor is started and closing it after a predetermined period of time.