JPH01139964A - Multi-chamber type air conditioner - Google Patents

Abstract

PURPOSE: To prevent lubricating oil from being diluted, by providing a solenoid valve on a refrigerant piping at a delivery port of each of a plurality of indoor units, and flowing a refrigerant passing through the heat exchanger of the indoor unit under operation into the indoor unit under interruption through a throttle mechanism for cooling. CONSTITUTION: An indoor unit under operation is judged to be an indoor unit 9' including an indoor heat exchanger 9, and simultaneously opens a heating inlet solenoid valve 11 and a cooling inlet solenoid valve 5, to which a refrigerant is flowed. Further, the indoor unit in interruption is judged to be an indoor unit 10' including an indoor heat exchanger 10 to open a cooling inlet solenoid valve 6 but with a heating inlet solenoid valve 12 kept closed intactly. As a result, the refrigerant flows to the indoor heat exchanger 10 after passage through a throttle mechanism 8 for cooling with more reduced resistance than a throttle mechanism 4 for heating. Once a predetermined time is elapsed after the operation is started, a solenoid valve 6 of an interruption indoor unit is closed. The refrigerant is gradually returned from a capillary 17 to a compressor low pressure side. As a result, upon operation starting with the reduced number of the indoor units dilution of lubricating oil due to residual refrigerant return to the compressor is restricted, and hence reliability of the compressor is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a multi-chamber air conditioner, and in particular, a method suitable for properly lubricating sliding parts of a compressor at the time of starting heating operation. This invention relates to a multi-room air conditioner.

[Conventional technology]

For example, in an inverter-type refrigeration cycle where the rotation speed of the compressor is variable, as described in Japanese Patent Application Laid-Open No. 61-83833, when low-speed rotation continues such that lubricating oil is insufficient, The configuration was such that the compressor rotated at high speed and the throttle mechanism was adjusted to improve the flow of refrigerant.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology shows a technique for dealing with the lack of lubricating oil when the compressor operates at low speed, but it does not take into consideration when a multi-room air conditioner having multiple indoor units starts operation with a small number of units. The lubricating oil inside the compressor is diluted due to excess refrigerant returning to the compressor at startup, and the viscosity of the lubricating oil decreases as the discharge pressure increases, resulting in a decrease in the thickness of the oil film on the sliding parts of the compressor. The problem remained.

The present invention was made in order to solve the problems of the prior art described above, and when starting operation of a small number of indoor units where the discharge pressure tends to be high, the lubricating oil becomes diluted due to surplus refrigerant returning to the compressor. The object of the present invention is to provide a multi-chamber air conditioner that can maintain an appropriate oil film thickness on the sliding parts of the compressor and improve the reliability of the compressor.

[Means for solving problems]

In order to achieve the above object, the configuration of the multi-room air conditioner according to the present invention includes one outdoor unit and a plurality of indoor units, and connects a refrigerant piping system to enable switching between cooling and heating modes. In this multi-room air conditioner, a solenoid valve is installed in the refrigerant pipe at the inlet and outlet of each of the plurality of indoor units, and a solenoid valve is installed in the refrigerant pipe at the entrance and exit of each of the plurality of indoor units. A signal detection means is provided to receive each signal indicating a cold start, and when a cold start is performed during heating operation, the heating inlet solenoid valve of the stopped indoor unit is kept closed, and the cooling of the stopped indoor unit is started. When the inlet solenoid valve is opened for a certain period of time, the indoor unit at the stop/main position is
This device is equipped with a control means that allows the refrigerant that has passed through the heat exchanger of the indoor unit during operation to flow in through the cooling throttle mechanism. [Function] The technology of the present invention is required during heating operation. The reason for this is that refrigerant always passes through the condenser during cooling operation, and the condenser usually has a capacity sufficient to store excess refrigerant.

Therefore, in the present invention, a heating operation command signal is received from the indoor unit, and a large amount of refrigerant is discharged. Therefore, the technique of the present invention is not necessary when the compressor is operated within several minutes after the operation is stopped, which is called a normal warm start when the temperature of the flat compressor is high. □ Therefore, as a means to detect only when the compressor is at a low temperature, a detecting means such as a thermistor is provided in the compressor body, and the present invention operates only when the signal is a value indicating that the temperature is below a certain level. I do.

In addition, to determine which indoor unit is stopped, the unit for which there is no operation instruction signal from the indoor unit is determined to be the stopped unit, and then the cooling inlet side flf of the stopped unit is determined.
Therefore, the control means of the present invention is designed to open only the fl valve, and therefore, the control means of the present invention has three conditions: heating operation, other indoor units are stopped, and compressor temperature is low and cold start is performed. It will not operate unless the signal is confirmed, and will not malfunction.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3.

Fig. 1 is a refrigeration cycle system diagram of a multi-chamber air conditioner according to an embodiment of the present invention, Fig. 2 is a control system diagram of the multi-chamber air conditioner of Fig. 1, and Fig. 3 is its control system diagram. FIG. 3 is a flowchart diagram showing the procedure of control operation.

In FIG. 1, reference numeral 1 denotes a compressor, which may be of a constant rotation speed or may be of an inverter type whose rotation speed can be varied. 2 is a four-way switching valve, and this four-way switching valve 2 directs the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 to the outdoor heat exchanger 3 on the outdoor unit side during cooling, and to the indoor heat exchanger 3 during heating. The flow path is switched to selectively flow to the indoor heat exchangers 9 and 10 on the unit side.

4 is a diaphragm mechanism for heating, 5 and 6 are inlet solenoid valves for cooling, 7,
8 is a cooling throttle mechanism, 9.10 is an indoor heat exchanger, 11
．． 12 is a heating inlet solenoid valve. The cooling inlet f4 solenoid valves 5, 6 and the heating inlet solenoid valves 11, 12 are arranged in the refrigerant piping at the entrance and exit of each indoor unit having the indoor heat exchangers 9, 10.

18 is a check valve installed in parallel with the heating throttle mechanism 4;
Reference numerals 9 and 20 indicate check valves installed in parallel with the cooling throttle mechanisms 7 and 8, each of which has a function of allowing refrigerant to flow only in the direction of the arrow, and bypassing each of the aforementioned throttle mechanisms when the refrigerant flows in the direction of the arrow. have.

16.17 indicates that during heating operation, when the inlet/outlet solenoid valve of the indoor unit that is not in operation is closed, the refrigerant that leaks from the inlet side solenoid valves 5 and 6 during heating and accumulates is transferred to the compressor suction side. This is a capillary for returning to the pipe 14.

Reference numeral 13 indicates a pipe that is on the discharge side and becomes high pressure during heating operation. 21 is an accumulator that has a gas-liquid separator function to prevent the refrigerant from returning to the compressor in liquid form.

The operation of general heating and cooling operation in a refrigeration cycle having such a configuration will be explained.

During cooling operation, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows through the four-way switching valve 2 to the outdoor heat exchanger 3 (acting as a condenser), radiates heat to the outdoor air, and is condensed into high-pressure liquid. Becomes a refrigerant. This liquid refrigerant passes through the check valve 18, and a flow path is selected by opening the cooling inlet solenoid valve 5 or 6. For example, when the cooling inlet solenoid valve 5 is opened,
The pressure is reduced through the cooling throttle mechanism 7, and the indoor heat exchanger 9 (acts as an evaporator) exchanges heat with the indoor air to become a gaseous refrigerant. A well-known cooling operation is carried out by passing through the piping 13 (electromagnetic valve) 11, passing through the four-way switching valve 2, returning to the compressor 1 via the compressor suction side piping 14, and the accumulator 21, and repeating the same cycle thereafter.

When the cooling inlet solenoid valve 6 and the outlet solenoid valve 12 are selectively opened, the refrigerant flows through the cooling throttle mechanism 8, the indoor heat exchanger 1o, and the outlet solenoid valve (heating inlet solenoid valve) 12. becomes.

It goes without saying that it is also possible to open all of the electromagnetic valves 5, 6, 11, 12 and allow the refrigerant to flow through both the indoor heat exchangers 9, 10 at the same time.

In general, even when operating a small number of indoor units (such as when only one indoor unit is operated), surplus refrigerant is generated because the refrigerant is filled with enough refrigerant to operate all indoor units at the same time, but it usually condenses. Since the container has sufficient capacity, excess refrigerant can be stored in it as liquid refrigerant, and if there is still insufficient refrigerant, the receiver tank 2, which is a liquid receiver, is used.
2, and by storing liquid refrigerant there, the amount of liquid refrigerant can be adjusted.

On the other hand, during heating operation, the high temperature and high pressure gaseous refrigerant discharged from the compressor 1 is transferred through the heating inlet solenoid valve 11.1 through the piping 13 by switching the four-way switching valve 2 to the heating side.
2. When the heating inlet solenoid valve 11 is selectively opened, the cooling inlet solenoid valve (heating outlet solenoid valve) 5 is opened.
The refrigerant flows into the indoor heat exchanger (acting as a condenser) 9, where it radiates heat into the indoor air and condenses to become a liquid refrigerant. For liquid refrigerant, check valve 19. The pressure is reduced through the solenoid valve 5 and the heating throttle mechanism 4, and the outdoor heat exchanger (acts as an evaporator) 3
It exchanges heat with outside air and evaporates, becoming a low-temperature, low-pressure gaseous refrigerant, which passes through the four-way selector valve 2 and enters the compressor suction side pipe 14. It passes through the accumulator 21 and returns to the compressor 1, and thereafter the same cycle is repeated to perform a well-known heat pump type heating operation.

When the heating inlet solenoid valve 12 is selectively opened, the cooling inlet solenoid valve (heating outlet solenoid valve) 6 on the outlet side thereof is opened, and the indoor heat exchanger 10 is opened. Check valve 20. Similar refrigerant circulation through the solenoid valve 6 is performed to perform heating operation, of course.
Simultaneous operation in all rooms in which refrigerant flows through all indoor heat exchangers is also possible.

When operating a small number of indoor units in such general heating operation, surplus refrigerant is generated as in cooling operation, but
The refrigerant that comes out of the compressor 1 is a high-temperature, high-pressure gaseous refrigerant until it reaches the indoor heat exchanger, and even if a container is placed between the compressor and the indoor heat exchanger, it is gaseous and has a specific volume. Since it is a large refrigerant, it is impossible to store excess refrigerant. Since the capacity of the indoor heat exchanger is reduced to 1/2 to a fraction of the capacity when all units are in operation, sufficient heat radiation is not achieved and the discharge pressure increases.
At the time of startup, a large amount of refrigerant and lubricating oil dissolved therein are taken out all at once, and the oil level inside the compressor temporarily drops, resulting in a mechanical lock. Furthermore, when the discharge pressure is high, the temperature of the refrigerant and lubricating oil also increases, and the viscosity of the lubricating oil decreases, making it impossible to maintain the thickness of the oil film on the sliding parts of the compressor. Additionally, since the system is operated with a surplus of refrigerant, a few minutes after the refrigerant circulates through the refrigeration cycle and returns, too much refrigerant returns to the compressor, diluting the lubricating oil with the refrigerant and causing lubrication problems. .

The present invention was developed to solve such problems, and one embodiment thereof will be described with reference to FIGS. 2 and 3 in conjunction with FIG. 1.

In FIG. 2, 23 is a thermistor that detects the main body temperature of the compressor 1, and 24 is a thermistor that detects the operating signals, cooling and heating signals from the first indoor unit q and the second indoor unit 1σ, and the signal of the thermistor 23. a control unit that determines and controls which of the four-way switching valve 4 and each solenoid valve to open or close;
is a solenoid valve control unit that opens and closes each solenoid valve according to judgments and commands from the control unit 24. Control unit 24, solenoid valve control unit 25
consists of arithmetic control means such as a microcomputer, and functions as a signal detection means that receives three signals: heating operation, small number operation, and cold start due to low compressor temperature.

It has a function as a control means that performs the control described below.

The operation will be explained according to the procedure (step N09) of the flowchart shown in FIG.

When the operation is started, the control unit 24 controls the first and second indoor units q and 1σ and the thermistor 2 as shown in FIG.
Take in the signal of 3.

Determine whether the operation is heating operation (step ■)
. If it is heating operation, the four-way switching valve 2 is energized and switched to the heating side.

It is determined whether the temperature of the compressor 1 is below a predetermined temperature (for example, 50° C.) (step ■), and if it is below the predetermined temperature, it is determined that the operation of the present invention is necessary because it is a cold start, and the solenoid valve control section Send a signal to 25.

In this embodiment, an example in which the indoor heat exchanger 9 operates will now be described.

Therefore, the indoor unit being operated is the indoor heat exchanger 9.
(step ■), and within a predetermined time from the start of operation (step At the same time, the outlet solenoid valve) 5 is opened (step ■).

Furthermore, the indoor unit that is stopped is the indoor heat exchanger 1o.
It is determined that the second indoor unit 10' has a
In step (2), the cooling inlet solenoid valve 6 is opened. During heating, the inlet solenoid valve 12 remains closed (step ■).

As a result, the refrigerant flows in the order of the heating solenoid valve 11 → the indoor heat exchanger 9 → the check valve 19 → the cooling inlet solenoid valve (heating outlet solenoid valve) 5, and the cooling inlet solenoid valve 6. is open, the indoor heat exchanger 1 passes through the cooling throttle mechanism 8 on the indoor heat exchanger 10 side, which has less resistance than the heating throttle mechanism 4.
Flows to 0.

Since the indoor heat exchanger 10 is stopped, the temperature is generally lower than the ambient temperature, and since it is drawn to the low pressure side of the compressor by the capillary 17, the pressure inside the indoor heat exchanger 10 is low. Furthermore, since the refrigerant flowing from the cooling throttle mechanism 2o has already been condensed and liquefied in the indoor heat exchanger 9, the refrigerant flows into the indoor heat exchanger 10.
can store a sufficient amount of excess refrigerant. Therefore.

The total amount of circulating refrigerant is reduced, and in addition, the indoor heat exchanger 10
However, since some heat is radiated, the discharge pressure does not increase.

When a certain period of time (several minutes) has passed after the start of operation (step ■), the refrigeration cycle becomes stable, so the cooling inlet solenoid valve 6 of the stopped indoor unit is closed (step ■), and the refrigerant is gradually transferred from the capillary 17 to the compressor. Return to the low pressure side.

Note that when the compressor temperature is high and the compressor is restarted after being turned off for a short time by the thermostat, the above operation is not performed, and normal operation is performed in which only the inlet and outlet solenoid valves of the operating indoor unit are opened.

In order to reduce the amount of refrigerant being circulated, we started by operating a small number of units, suppressing the increase in discharge pressure at the start of operation when the discharge pressure would be high, and reducing the amount of circulating refrigerant without installing a special container such as a receiver tank.
Surplus refrigerant can be temporarily stored in the indoor heat exchanger of a stopped indoor unit. Therefore, it is possible to prevent the lubricating oil from being carried out all at once at the start of operation, maintain the thickness of the oil film on the sliding parts inside the compressor, and further suppress the dilution of the oil due to surplus refrigerant returning to the compressor from time to time. You can also
This has a significant effect on improving compressor reliability.

Also, in terms of cost, there are almost no additional refrigeration cycle parts, so the effect is great.

In addition, in the above-mentioned embodiment, an example was explained in which there are two indoor units and one of them operates, but it is possible to operate in the same way even when there are three or more indoor units and a small number of them are operated. it is obvious.

〔Effect of the invention〕

As described above, according to the present invention, when starting operation of a small number of indoor units where the discharge pressure tends to be high, dilution of lubricating oil due to excess refrigerant returning to the compressor can be suppressed, and an oil film on the sliding parts of the compressor can be prevented. It is possible to provide a multi-chamber air conditioner in which the thickness can be kept appropriate and the reliability of the compressor can be improved.

[Brief explanation of the drawing]

FIG. 1 is a refrigeration cycle system diagram of a multi-chamber air conditioner according to an embodiment of the present invention, FIG. 2 is a control system diagram of the multi-chamber air conditioner of FIG. 1, and FIG. 1. Compressor, 2. Four-way switching valve, 3. Outdoor heat exchanger, 4. Heating throttle mechanism, 5, 6. ... Cooling inlet solenoid valve, 7, 8...
Cooling throttle mechanism, 9, 10... indoor heat exchanger, g.
...First indoor unit, 10'...Second indoor unit, 11.12...Heating inlet solenoid valve, 13...
Piping, 14... Compressor suction side piping, 16.17...
Capillary, 18, 19, 20... Check valve, 23...
- Thermistor, 24... control section, 25... solenoid valve control section.

Claims (1)

[Claims] 1. In a multi-room air conditioner in which a single outdoor unit is equipped with a plurality of indoor units and a refrigerant piping system is connected to enable switching between cooling and heating operation, the refrigerant at the entrance and exit of each of the plurality of indoor units is In addition to installing a solenoid valve in the piping, a signal detection means is installed to receive signals indicating that heating operation is in progress, that other indoor units are stopped, and that compressor temperature is low and cold start is being performed. When performing a cold start, the cooling inlet solenoid valve of the stopped indoor unit is opened for a certain period of time while the heating inlet solenoid valve of the stopped indoor unit is kept closed, and the cooling inlet solenoid valve of the stopped indoor unit is opened for a certain period of time. A multi-room air conditioner characterized by being provided with a control means for causing refrigerant that has passed through a heat exchanger in an indoor unit to flow in through a cooling throttle mechanism.