JP2533585B2 - Multi-room air conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multi-room air conditioner, and in particular, it is suitable for proper lubrication of a sliding part of a compressor at the start of heating operation.
The present invention relates to a multi-room air conditioner.

[Conventional technology]

The conventional device, for example, as described in JP-A-61-83833, in the inverter type refrigeration cycle in which the number of revolutions of the compressor is variable, when the low speed rotation such that the lubricating oil is insufficient continues, The compressor was rotated at a high speed, and the throttle mechanism was adjusted to improve the flow of the refrigerant.

[Problems to be solved by the invention]

Although the above-mentioned conventional technique shows a technique for a shortage of lubricating oil during low-speed operation of the compressor, consideration should be given to starting a small number of multi-room air conditioners having a plurality of indoor units. Not done, the excess refrigerant returned to the compressor at the time of start-up, the lubricating oil in the compressor was diluted, and the viscosity of the lubricating oil decreased with the increase of discharge pressure, and the oil film thickness of the sliding part of the compressor decreased. Problem was left.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and at the time of starting the operation of a small number of indoor units where the discharge pressure tends to be high pressure, the lubricating oil is diluted by the excess refrigerant returning to the compressor. It is an object of the present invention to provide a multi-room air conditioner capable of maintaining an appropriate oil film thickness on a sliding portion of a compressor and improving 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 is provided with a plurality of indoor units in one outdoor unit, and connecting a refrigerant piping system to enable switching between cooling and heating operations. In a multi-room air conditioner consisting of, a solenoid valve is provided in the refrigerant pipe at the entrance and exit of each of the plurality of indoor units, and it is in heating operation, other indoor units are stopped, and the temperature of the compressor is A signal detecting means for receiving each low cold start signal is provided, and when the cold start is performed in the heating operation, the indoor unit that is stopped is cooled while the inlet solenoid valve for heating the indoor unit that is stopped is closed. Open the time inlet solenoid valve for a certain period of time, and in the stopped indoor unit,
The control means is provided so that the refrigerant passing through the heat exchanger of the operating indoor unit is caused to flow in through the cooling throttle mechanism.

[Action]

The technique of the present invention is required only during the heating operation, because the refrigerant always passes through the condenser during the cooling operation, and the capacity is usually sufficient to store excess refrigerant. Because it has.

Therefore, in the present invention, the signal of the heating operation command from the indoor unit is received, and the large amount of refrigerant is discharged because the compressor is stopped for a long time and the refrigerant is accumulated in the compressor. It is in the state. Therefore, the technique of the present invention is not necessary when the operation is performed within a few minutes after the operation is stopped, that is, when the temperature of the compressor is high, which is called a normal warm start.

Therefore, as a means for detecting only when the compressor is at a low temperature, a detecting means such as a thermistor is provided in the compressor body, and the operation of the present invention is performed only when the signal has a value indicating that the temperature is below a certain temperature. To do. Further, which unit is the stopped indoor unit is determined such that a unit having no operation instruction signal from the indoor unit is the stopped unit, and only the cooling inlet side solenoid valve of the stopped unit is opened. Therefore, the control means of the present invention does not operate except when the three signals that the heating operation, the other indoor units are stopped, and the compressor temperature is low and cold start are confirmed. , Does not malfunction.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a refrigeration cycle system diagram of a multi-room air conditioner according to an embodiment of the present invention, FIG. 2 is a control system diagram of the multi-room air conditioner of FIG. 1, and FIG. It is a flowchart figure which shows the procedure of control operation.

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

4 is a throttle mechanism for heating, 5 and 6 are solenoid valves for cooling, 7, 8 are throttle mechanisms for cooling, 9 and 10 are indoor heat exchangers, and 11 and 12 are solenoid valves for heating. The cooling inlet solenoid valves 5 and 6 and the heating inlet solenoid valves 11 and 12 are arranged in the cooling pipes at the entrance and exit of each indoor unit having the indoor heat exchangers 9 and 10.

18 is a check valve installed in parallel with the heating throttle mechanism 4, 1
Reference numerals 9 and 20 are check valves installed in parallel with the cooling throttle mechanisms 7 and 8, both of which allow the refrigerant to flow only in the direction of the arrow and have a function of bypassing each of the above throttle mechanisms when the refrigerant flows in the direction of the arrow. To have.

Refrigerators 16 and 17 are the refrigerant suction side of the refrigerant that leaks and flows from the inlet side solenoid valves 5 and 6 during heating when the inlet and outlet solenoid valves of the indoor unit that is stopped during heating are closed. A capillary for returning to the pipe 14.

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

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

During the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows through the four-way switching valve 2 to the outdoor heat exchanger (acting as a condenser), radiates heat to the outdoor air and is condensed to be a high-pressure liquid refrigerant. Becomes This liquid refrigerant passes through the check valve 18 and the flow passage is selected by opening the cooling inlet solenoid valve 5 or 6, and for example, when the cooling inlet solenoid valve 5 is opened, the cooling throttle mechanism 7 is opened. After being decompressed, it passes through the indoor heat exchanger 9 (acting as an evaporator) and exchanges heat with the indoor air to become a gaseous refrigerant, and the heating inlet solenoid valve (cooling outlet solenoid valve) 11 that is selectively opened. Through the pipe 13 and the four-way selector valve 2,
Compressor 1 through the suction side pipe 14 and the accumulator 21
Then, the well-known cooling operation is repeated by repeating the same cycle.

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 10 and the outlet solenoid valve (heating inlet solenoid valve) 12. Become.

Needless to say, it is possible to open all of the solenoid valves 5, 6, 11, 12 and allow the refrigerant to flow through both the indoor heat exchangers 9, 10 at the same time.

Generally, even when operating only a small number of indoor units in a cooling system, the refrigerant is filled with a sufficient amount of refrigerant to operate all the indoor units at the same time. Since the container has a sufficient capacity, excess refrigerant can be stored in it as liquid refrigerant, and if there is still a shortage, receiver tank that is the receiver
22 is provided and the amount of the liquid refrigerant can be adjusted by storing the liquid refrigerant therein.

On the other hand, during the heating operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 1 reaches the heating inlet solenoid valves 11 and 12 via the pipe 13 by switching the four-way switching valve 2 to the heating side. When the heating inlet solenoid valve 11 is selectively opened, the cooling inlet solenoid valve (heating outlet solenoid valve) 5 is opened, and the refrigerant is allowed to flow to the indoor heat exchanger (acting as a condenser) 9 side. At this point, the heat is condensed into the room air to become a liquid refrigerant. The liquid refrigerant passes through the check valve 19 and the solenoid valve 5 and is decompressed through the heating throttling mechanism 4. The outdoor heat exchanger (acting as an evaporator) 3 exchanges heat with the outside air to evaporate, and the low temperature low pressure gas. Becomes refrigerant and passes through the four-way switching valve 2 and the compressor suction side pipe 14, accumulator
It returns to the compressor 1 through 21 and performs the well-known heat pump heating operation in which the same cycle is repeated thereafter.

When the heating inlet solenoid valve 12 is selectively opened, the cooling inlet solenoid valve (heating outlet solenoid valve) 6 corresponding to the outlet side is opened, and the indoor heat exchanger 10, the check valve 20, the solenoid The same refrigerant circulation through the valve 6 is performed to perform the heating operation. Of course, it is also possible to perform simultaneous operation in all rooms, in which the refrigerant flows through all the indoor heat exchangers.

In such a general heating operation, when a small number of indoor units are operated, excess refrigerant is generated as in the cooling operation, but the refrigerant discharged from the compressor 1 reaches high temperature and high pressure until it reaches the indoor heat exchanger. Even if a container is placed between the compressor and the indoor-side heat exchanger, it is a gaseous refrigerant having a large specific volume, so that it is impossible to store excess refrigerant. The capacity of the indoor heat exchanger is 1/2 to a fraction of that when all units are in operation
Therefore, sufficient heat is not released and the discharge pressure becomes high, and at the time of start-up, a large amount of refrigerant and lubricating oil dissolved therein are taken out, and the oil level in the compressor temporarily drops,
It comes to mechanical locking. Further, the fact that the discharge pressure is high also causes the temperatures of the refrigerant and the lubricating oil to rise, the viscosity of the lubricating oil decreases, and the oil film thickness of the compressor sliding portion cannot be maintained. Further, since the refrigerant is operated in excess, the refrigerant returning to the compressor becomes excessive after a few minutes when the refrigerant circulates in the refrigeration cycle and returns, and the lubricating oil is diluted with the refrigerant, and at the same time causes inconvenience in lubrication. .

The present invention was developed to solve such a problem, and one embodiment thereof will be described with reference to FIGS.

In FIG. 2, reference numeral 23 denotes a thermistor for detecting the temperature of the main body of the compressor 1, 24 denotes operation signals from the first indoor unit 9'and the second indoor unit 10 ', cooling and heating signals, and the thermistor 23. A control unit that receives a signal and determines and controls which of the four-way switching valve 4 and each solenoid valve is to be opened and closed, and 25 is a solenoid valve control unit that opens and closes each solenoid valve according to the determination and commands of the control unit 24. . The control unit 24 and the solenoid valve control unit 25 are composed of arithmetic control means such as a microcomputer, and output three signals of heating operation, small number operation, and cold start of the compressor. It has a function as a signal detecting means for receiving and a function as a controlling means for performing the control described below.

The operation will be described according to the procedure (step NO.) Of the flowchart shown in FIG.

When the operation is started, the control unit 24 controls the first and second indoor units 9'and 10 'and the thermistor 2 as shown in FIG.
Capture the signal of 3.

It is determined whether the operation is heating operation (step). During heating operation, the four-way switching valve 2 is energized to switch to the heating side.

It is judged whether or not the temperature of the compressor 1 is below a predetermined temperature (for example, 50 ° C.) (step).
Signal to 25.

Now, in the present embodiment, an example in which the indoor heat exchanger 9 operates will be described.

Therefore, it is judged that the operating indoor unit is the first indoor unit 9'having the indoor heat exchanger 9 (step), and the refrigerant is allowed to flow therethrough within a predetermined time (step) from the start of operation. The heating inlet solenoid valve 11 and the cooling inlet solenoid valve (heating outlet solenoid valve) 5 are simultaneously opened (step). Further, it is determined (step) that the stopped indoor unit is the second indoor unit 10 'having the indoor heat exchanger 10, and the cooling inlet solenoid valve 6 is opened. The inlet solenoid valve 12 is kept closed during heating (step).

As a result, the refrigerant flows in the order of the heating inlet 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 Since it is open, it flows to the indoor heat exchanger 10 through the cooling throttle mechanism 8 on the indoor heat exchanger 10 side, which has less resistance than the heating throttle mechanism 4. Since the indoor heat exchanger 10 is stopped, it is generally lower than the ambient temperature, and further, because it is pulled to the compressor low pressure side by the capillary 17, the inside of the indoor heat exchanger 10 is at a low pressure, Further, since the refrigerant flowing from the cooling throttle mechanism 20 is already condensed in the indoor heat exchanger 9 and is in a liquid state, a sufficient amount of excess refrigerant is stored in the indoor heat exchanger 10. be able to. Therefore, the total amount of circulating refrigerant decreases, and in addition, the indoor heat exchanger 10 also slightly radiates heat, so the discharge pressure does not increase.

A certain time (several minutes) has passed since the start of operation (step)
Then, since the refrigeration cycle is stabilized, the cooling inlet solenoid valve 6 of the stopped indoor unit is closed (step). The refrigerant gradually returns from the capillary 17 to the low pressure side of the compressor.

It should be noted that when the compressor temperature is high, the above operation is not performed when restarting after being turned off for a short time by the thermostat, and normal operation in which only the inlet / outlet solenoid valve of the operating indoor unit is opened is performed.

According to the present embodiment, in the heating operation, the compressor is cold, the small number of units operation is performed from the state where the refrigerant is accumulated in the compressor, and the discharge pressure of the discharge pressure becomes high at the start of the operation. The surplus refrigerant can be temporarily stored in the indoor heat exchanger of the stopped indoor unit so as to suppress the rise and reduce the circulating refrigerant amount without providing a special container such as a receiver tank. Therefore, it is possible to prevent all of the lubricating oil from being taken out at the start of operation, to maintain the oil film thickness of the sliding portion inside the compressor, and to suppress the oil dilution due to the excess refrigerant returning to the compressor during one cycle of the refrigerant. It also has a great effect on improving the reliability of the compressor.

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

In addition, in the above-described embodiment, the example in which the number of indoor units is two and one of the indoor units is operated has been described, but the same operation may be performed when a small number of indoor units are operated. it is obvious.

〔The invention's effect〕

As described above, according to the present invention, at the time of starting the operation of a small number of indoor units in which the discharge pressure is likely to be high, it is possible to suppress the dilution of the lubricating oil due to the return of the excess refrigerant to the compressor, and to reduce the oil film of the compressor sliding portion. It is possible to provide a multi-room air conditioner that can maintain the thickness appropriately and improve the reliability of the compressor.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle system diagram of a multi-room air conditioner according to an embodiment of the present invention, FIG. 2 is a control system diagram of the multi-room air conditioner of FIG. 1, and FIG. It is a flowchart figure which shows the procedure of the control operation. 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, 9 '... First indoor unit, 10' ... Second indoor unit, 11,12 ... Heating inlet solenoid valve, 13 ... Piping, 1
4 …… Compressor suction side piping, 16,17 …… Capillary, 18,19,
20 …… Check valve, 23 …… Thermistor, 24 …… Control part, 25…
… Solenoid valve controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Nakamura Inventor Hiroyuki Nakamura 800 Oita, Ohira-cho, Shimotsuga-gun, Tochigi Ltd. Tochigi Plant, Hitachi, Ltd. (56) Reference JP-A-63-233259 (JP, A)

Claims (1)

(57) [Claims] 1. A multi-room air conditioner comprising a plurality of indoor units in one outdoor unit, and a refrigerant piping system connected to enable switching between cooling and heating operations. An electromagnetic valve is provided in the refrigerant pipe at the entrance and exit, and signal detection means is provided for receiving signals that the heating operation is being performed, that the other indoor units are stopped, and that the temperature of the compressor is low and cold starting is performed. When the engine is cold-started in the heating operation, while keeping the heating inlet solenoid valve of the stopped indoor unit closed, the cooling inlet solenoid valve of the stopped indoor unit is opened for a certain period of time to the stopped indoor unit, A multi-room air conditioner comprising a control means for causing a refrigerant that has passed through a heat exchanger of an indoor unit that is operating to flow in through a cooling throttling mechanism.