JPH10253189A - Air conditioning system - Google Patents

Abstract

(57) [Problem] To provide an air conditioning system capable of operating normally even when the number of operating indoor units suddenly increases in a heating operation. An outdoor unit includes a gas burner, and vaporizes a refrigerant using heat energy generated by combustion of the gas burner.
The refrigerant vaporized in the outdoor unit 10 is condensed in the indoor unit 20,
The condensed refrigerant is returned to the outdoor unit 10 via the pump 30. A plurality of indoor units 20 are provided, and when the control unit 40 detects an increase in the number of operating indoor units 20, the combustion is started unless the gas burner is burning at that time. Further, when detecting an increase in the number of operating indoor units 20, the control means 40 continues the combustion of the gas burner for a certain forced operation time from the start of combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relatively large-scale air conditioning system used for buildings and the like.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a conventional air conditioning system of this kind. The air conditioning system shown
JP-A-8-313002, JP-A-8-31299
No. 9 and the like,
Basically, by circulating a refrigerant (for example, R134a) so as to transfer heat between the outdoor unit 10 and the indoor unit 20, it is possible to cool and heat the room. The outdoor unit 10 switches the operation state between the time of cooling and the time of heating as described later, and cools or heats the refrigerant.

[0003] The outdoor unit 10 is disposed above all the indoor units 20, and the lower portion of the indoor unit 20 is connected via a refrigerant liquid pipe 31 and a cooling / heating switching valve 33 connected to a lower portion of the outdoor unit 10. The upper part of the unit 20 is connected to the upper part of the outdoor unit 10 via the refrigerant gas pipe 32. A liquid receiving tank 34 is arranged below all the indoor units 20, and the liquid refrigerant in the liquid receiving tank 34 is pumped to the outdoor unit 10 through the pump 30 and the check valve 35. The pump 30 is disposed below the liquid receiving tank 34. The inlet of the liquid receiving tank 34 and the outlet of the check valve 35 are connected to respective ends of the cooling / heating switching valve 33.

During the cooling operation, the cooling / heating switching valve 33 is opened, the refrigerant is condensed in the outdoor unit 10, and the refrigerant liquid piping 31
, Flows into the indoor unit 20 and evaporates in the indoor unit 20 to take heat from the room. The evaporated refrigerant rises up the refrigerant gas pipe 32 due to the pressure difference between the condensation pressure in the outdoor unit 10 and the evaporation pressure in the indoor unit 20 and returns to the outdoor unit 10. Indoor cooling is performed by such natural circulation of the refrigerant. That is, in order to send the weight of the refrigerant from the outdoor unit 10 to the indoor unit 20, the outdoor unit 10 is provided at a position higher than all the indoor units 20.

On the other hand, during the heating operation, the cooling / heating switching valve 33 is closed, and the refrigerant in the liquid state stored in the liquid receiving tank 34 is pumped up by the pump 30 and sent to the outdoor unit 10 through the refrigerant liquid pipe 31 to be sent to the outdoor unit 10. To evaporate. The evaporated refrigerant is sent to the indoor unit 20 through the refrigerant gas pipe,
The heat is released indoors by being condensed in the indoor unit 20. The refrigerant condensed in the indoor unit 20 is stored in the liquid receiving tank 34.

The heat load of the indoor unit 20 varies depending on various factors, and it is necessary to adjust the supply amount of the refrigerant according to the heat load. For this adjustment, a liquid receiving tank 34 is provided, and the refrigerant condensed in the indoor unit 20 is once recovered in the liquid receiving tank 34 so that the supply amount of the refrigerant follows the fluctuation of the heat load. I have. That is, if the heat load is increased by storing the refrigerant in the liquid receiving tank 34, the supply amount of the refrigerant from the liquid receiving tank 34 is increased, and if the heat load is reduced, the amount of the refrigerant supplied from the liquid receiving tank 34 is increased. Can be reduced. A liquid level switch 36 is provided in the liquid receiving tank 34.
Is provided to monitor that the liquid level of the refrigerant does not drop too much.

As shown in FIG. 2, each indoor unit 20 includes a coil unit 21, a fan 22, and an expansion valve 23. The amount of heat transferred between the indoor units 20 according to the opening and closing of the expansion valve 23 is controlled. It is supposed to be. Therefore,
The operation of the indoor unit 20 can be stopped by closing the expansion valve 23, and the room temperature of each room can be individually adjusted by opening and closing the expansion valve 23.

The outdoor unit 10, the expansion valve 23, and the pump 3
The control of the cooling / heating switching valve 33 and the monitoring of the liquid level switch 36 are performed by a control circuit (not shown). by the way,
As described in JP-A-9-26187 and JP-A-9-26188, each indoor unit 20 includes temperature sensors 24a and 24b before and after the coil unit 21. The opening and closing of the expansion valve 23 is controlled so that the temperature difference is maintained at the set predetermined temperature.
Temperature detection by the temperature sensors 24a and 24b and the expansion valve 2
3 is the controller 2 provided in each indoor unit 20.
5, and control according to the load is performed for each indoor unit 20.

[0009]

Now, in the heating operation, if the number of operating indoor units 20 increases and the load increases suddenly, the amount of refrigerant condensed in the indoor units 20 will increase rapidly. In such a case, the pressure inside the refrigerant gas pipe 32 suddenly decreases, and the refrigerant inside the refrigerant liquid pipe 31 also vaporizes. As a result, even the refrigerant inside the pump 30 may be gasified, and the pump 30 may not be able to send liquid normally.

[0010] Further, control may be considered in which the temperature of the refrigerant vaporized in the outdoor unit 10 is measured in the refrigerant gas pipe 32, and the heating amount of the outdoor unit 10 is switched according to the temperature of the refrigerant as shown in FIG. Have been. However, even if such control is performed, when the number of operating indoor units 20 suddenly increases, it is not necessarily reflected as a temperature change. Therefore, it is possible to reliably prevent gasification inside the pump 30. It cannot be done.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an air conditioning system capable of operating normally even when the number of operating indoor units suddenly increases in a heating operation. To provide.

[0012]

According to the present invention, there is provided an outdoor unit for vaporizing a refrigerant by using heat energy generated by combustion of a combustion means. The refrigerant vaporized by the outdoor unit is condensed in the indoor unit, and the condensed refrigerant is condensed in the indoor unit. An air conditioning system that returns the air to the outdoor unit via a pump is assumed. According to the first aspect of the present invention, a plurality of indoor units are provided and operation monitoring means for detecting the number of operating indoor units is provided, and the combustion means is burning when the increase in the number of operating indoor units is detected by the operation monitoring means. Otherwise, start the combustion, and when the operation monitoring means detects an increase in the number of operating indoor units, control the outdoor unit so that the combustion means continues to burn for a certain forced operation time from the start of the combustion. It is a feature. According to this configuration,
When the number of operating indoor units increases, the combustion means of the outdoor units are always burned. Can be prevented from dropping sharply. Moreover, when the operation of the indoor unit is started, the combustion is continued for a certain forced operation time from the start of combustion of the combustion means, so that the pressure sufficient to increase the number of operating indoor units can be maintained, and It is possible to prevent the refrigerant in the pump from being vaporized due to an excessive pressure drop. That is, even if the number of operating indoor units suddenly increases, the pump can be normally operated. The forced operation time is set to such an extent that the capacity of the pump and the outdoor unit can follow the increase in the number of operating indoor units, and after the elapse of the forced operation time, the operation state is normal.

According to a second aspect of the present invention, there is provided a coil unit for exchanging heat between a refrigerant and a room in an indoor unit, an expansion valve for selecting a state of permitting or prohibiting the passage of the refrigerant through the coil unit, and a coil. A temperature sensor that detects the temperature of the refrigerant before and after the unit, and a controller that opens and closes the expansion valve so as to keep the temperature difference of the temperature sensor substantially at a set value,
The controller prohibits the controller from opening and closing the expansion valve for a certain prohibition time from the start of combustion of the combustion means of the outdoor unit. According to this configuration, each indoor unit performs heat exchange according to the load amount by independently opening and closing the expansion valve as in the conventional configuration. In addition, since the opening and closing of the expansion valve is prohibited for a certain prohibition time from the start of combustion of the combustion unit of the outdoor unit, the combustion of the combustion unit of the outdoor unit is started until the pressure in the path from the outdoor unit to the indoor unit increases to some extent The opening and closing of the expansion valve is not performed, so that a rapid pressure drop due to the opening of the expansion valve can be prevented. The prohibition time is set to such an extent that the refrigerant inside the pump does not vaporize due to the pressure drop due to the opening of the expansion valve.

According to a third aspect of the present invention, there is provided a coil unit for performing heat exchange between a refrigerant and a room in an indoor unit, an expansion valve for selecting a state of permitting or prohibiting the passage of the refrigerant through the coil unit, and a coil. A temperature sensor that detects the temperature of the refrigerant before and after the unit, and a controller that opens and closes the expansion valve so as to keep the temperature difference of the temperature sensor substantially at a set value,
A plurality of indoor units are provided and operation monitoring means for detecting the number of operating indoor units is provided, and when the increase in the number of operating indoor units is detected by the operation monitoring means, combustion is started unless the combustion means is burning. When the increase in the number of operating indoor units is detected by the operation monitoring unit, the outdoor unit is controlled so that the combustion unit continues to burn for a certain forced operation time from the start of combustion, and the combustion unit of the outdoor unit starts burning. Therefore, the controller prohibits the controller from opening and closing the expansion valve for a certain prohibition time. This configuration is a combination of the configurations of the first and second aspects of the present invention. Since the pressure drop due to the opening of the expansion valve of the indoor unit is dealt with by both the outdoor unit and the indoor unit, the pump Gasification of the refrigerant in the inside can be more reliably prevented.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, the piping system has the same configuration as the conventional configuration, and is characterized by the control of the outdoor unit 10 and the indoor unit 20. As shown in FIG. 1, an outdoor unit 10, each indoor unit 20, a pump 30, a cooling / heating switching valve 3
3. The liquid level switch 36 is connected to a control circuit 40 composed of a microcomputer via a signal line Ls and is intensively monitored and controlled. Information is exchanged between the control circuit 40 and each device by data communication, but the description of this point is omitted. The indoor unit 20 has the same configuration as the conventional configuration, as shown in FIG.

Thus, the control circuit 40 can know which indoor unit 20 is operating (that is, detect whether the operation switch provided to each indoor unit 20 is turned on),
Therefore, the number of operating indoor units 20 can be known.
That is, the control circuit 40 functions as operation monitoring means.
The operation of the control circuit 40 will be described later, and the outdoor unit 10 used in the present embodiment will be described first. The outdoor unit 10 of the present embodiment performs an operation known as a double-effect absorption refrigerator during the cooling operation. FIG. 3 shows a principle diagram of a cooling cycle of this type of absorption refrigerator. absorption·
The inside of the evaporating chamber 11 is decompressed, and an absorber tube 11a through which cooling water passes and an evaporator tube 11b through which refrigerant passes are arranged apart from each other. The aqueous solution is sprayed, and water is sprayed on the evaporator tube 11b by the sprayer 11d. When the absorbent is sprayed on the absorber tube 11a, the internal pressure of the absorption / evaporation chamber 11 decreases, and the water sprayed on the evaporator tube 11b evaporates by removing heat from the refrigerant passing through the evaporator tube 11b. It is absorbed by the aqueous solution of the absorbent in the vessel 11a. At this time, heat of absorption is generated,
The heat of absorption is passed to the water passing through the absorber tube 11a. That is, the temperature of the aqueous solution of the absorbent is kept relatively low. Evaporator tube 11
The aqueous solution (dilute solution) of the absorbent which has absorbed the water evaporated in b and has become thinner is introduced into the low-temperature heat exchanger 13 by the solution circulation pump 12. The dilute solution heat-exchanged in the low-temperature heat exchanger 13 is branched into two, one of which is mixed with the high-concentration solution and the other is introduced into the high-temperature heat exchanger 14.

The dilute solution having a relatively high temperature through the high-temperature heat exchanger 14 is supplied to the high-temperature regenerator 15 by a gas burner 15a.
And boil. Therefore, the water solution evaporates and the aqueous solution of the absorbent becomes high temperature and high concentration (high temperature concentrated solution), exchanges heat with the dilute solution in the high temperature heat exchanger 14, and
After being mixed with a part of the low-temperature dilute solution to form a medium-concentration aqueous solution (intermediate-concentration solution), it is introduced into the low-temperature regenerator 16.
In the low-temperature regenerator 16, the intermediate concentrated solution is heated by heat exchange between the high-temperature steam obtained in the high-temperature regenerator 15 and the intermediate concentrated solution, the water is again evaporated, and the aqueous solution of the absorbent is lower in temperature than the high-temperature concentrated solution. And it becomes high concentration (low temperature concentrated solution).

The low-temperature concentrated solution obtained by the low-temperature regenerator 16 is heat-exchanged with the dilute solution by the low-temperature heat exchanger 13 and further cooled to a lower temperature and introduced into the sprayer 11c. On the other hand, the steam obtained by the low-temperature regenerator 16 is introduced into the condenser 17 and cooled and condensed by the cooling water passing through the cooling water pipe 17a, and the water obtained by the high-temperature regenerator 15 is condensed by the low-temperature regenerator 16 Together with the sprayer 11d. in this way,
When the aqueous solution concentration of the absorbent decreases as the refrigerant is cooled in the absorption / evaporation chamber 11, the water and the absorbent are separated by the high-temperature regenerator 15 and the low-temperature regenerator 16, and the absorbent and the water are reused. It is.

As described above, the water sprayed on the evaporator tube 11b inside the absorption / evaporation chamber 11 is evaporated by using the absorbent, so that heat of vaporization is taken and the refrigerant passing through the evaporator tube 11b is cooled. At this time, the diluted absorbent is used as a gas burner 1
The operation of concentrating using 5a or the like and circulating it for reuse is a basic operation. Thus, the outdoor unit 10 is actually configured by arranging the components shown in FIG. 3 as shown in FIG. The housing 18 of the outdoor unit 10 has a substantially cylindrical shape, in which an absorption / evaporation chamber 11 is provided at a lower portion, a low-temperature regenerator 16 is formed at an upper central portion, and a condenser 17 is formed at an upper outer peripheral portion. Have been. The absorber pipe 11a of the absorption / evaporation chamber 11 and the cooling water pipe 17a of the condenser 17 are wound around the vertical center line of the housing 18 and communicate with each other. Evaporator tube 14d
Is arranged on the outer peripheral side of the absorber tube 11b, and the absorber tube 11a
Similarly to the above, it is wound around a vertical center line of the housing 18. Sprayers 11c and 11d are arranged above absorber tube 11a and evaporator tube 11b, respectively.

The dilute solution collected in the lower part of the absorption / evaporation chamber 11 is passed through a low-temperature heat exchanger 13 and a high-temperature heat exchanger 14 by a pump 12 provided outside the housing 18 so that the high-temperature regenerator 1 is removed.
5 is introduced. The high-temperature regenerator 15 is provided with a gas burner 15a and heats the dilute solution directly. As a result, the dilute solution boils, and the steam and the high-temperature concentrated solution simultaneously rise in the liquid pumping tube 15b by the principle of a hot air bubble pump and are introduced into the separation chamber 15c. Since the opening of the separation chamber 15c is located above the bottom surface of the pumping pipe 15b, the high-temperature concentrated solution accumulates in the lower part of the separation chamber 15c, and the steam rises. Separation chamber 15
The high-temperature concentrated solution collected in the lower part of c passes through the high-temperature heat exchanger 14 and is mixed with a part of the dilute solution passed through the low-temperature heat exchanger 13 from the absorption / evaporation chamber 11. Sent to The steam separated in the separation chamber 15 c passes through a regenerator tube 16 a provided inside the low-temperature regenerator 16, exchanges heat with the high-temperature concentrated solution from the high-temperature heat exchanger 14, and is introduced into the condenser 17. Is done. Part of the water thus condensed in the condenser 17 returns directly to the sprayer 11d, and the rest returns to the sprayer 11d through the water proportional valve 17b. The high-temperature concentrated solution introduced into the low-temperature regenerator 16 is heated by steam passing through the regenerator tube 16a to generate steam, and the steam is introduced into the condenser 17 and is separated from the steam to have an increased concentration. The aqueous solution of the agent is supplied to the low-temperature heat exchanger 13
Through to the sprayer 11c.

By the way, in the heating cycle, the cooling / heating switching valve 19 is opened. That is, the bottom of the absorption / evaporation chamber 11 communicates with the separation chamber 15c. When the aqueous solution of the absorbent is heated by the gas burner 15a in the high-temperature regenerator 15, it rises in the liquid pumping pipe 15b in the same manner as in the cooling cycle, so that the separation chamber 15
c after being introduced into the cooling / heating switching valve 19
The refrigerant reaches the evaporation chamber 11 and exchanges heat with the refrigerant passing through the evaporator tube 11b to heat the refrigerant. Since the water vapor that has undergone heat exchange with the refrigerant is condensed, it is mixed with a high-concentration aqueous solution of the absorbent, and then returns to the high-temperature regenerator 15 through the pump 12, the low-temperature heat exchanger 13, and the high-temperature heat exchanger 14. It is.
Here, the low-temperature heat exchanger 13 and the high-temperature heat exchanger 14 do not perform any heat exchange.

The control circuit 40 controls the outdoor unit 10 and the indoor unit 20 as shown in FIGS. First, when an increase in the number of operating indoor units 20 is detected (S1), it is determined whether or not the gas burner 15a of the outdoor unit 10 is burning (S2). If not burning, a forced operation signal is generated to forcibly burn the gas burner 15a of the outdoor unit 10 (forced combustion mode) (S3). Until a predetermined time from the start of combustion of the gas burner 15a of the outdoor unit 10 (inhibition time) t ₁ has elapsed (S4), to prohibit the closing of the expansion valve 23 of the indoor unit 20 (valve control prohibition mode) (S5 ). That is, the expansion valve 23 that is open is kept open, and the expansion valve 23 that is closed is kept closed. After the lapse of the prohibition time t _1, it is determined whether the valve control prohibition mode (S6), to release the valve control inhibition mode if the indoor unit prohibition mode (S
7). Here, the valve control prohibition mode is not started with the combustion of the gas burner 15a, but is started with the gas burner 15a.
It starts from the time of fire extinguishing. Further, the prohibition time t ₁ from the time when the combustion of the gas burner 15a of the outdoor unit 10 starts.
The valve control prohibition mode is extended until elapses. Further, the forced operation time t ₂ (>) longer than the prohibition time t ₁ after the combustion of the gas burner 15a of the outdoor unit 10 is started.
When t ₁ ) elapses (S8), it is determined whether or not the forced combustion mode is set (S9). If the forced combustion mode is set, the forced combustion mode is canceled (S10). If the mode is not the forced combustion mode and the gas burner 15a is burning, the combustion is continued.

By controlling according to the procedure described above, FIG.
The following operation is performed. FIG. 6A shows an operation state of the indoor units 20. Here, four indoor units 20 are represented as A to D, respectively. In other words, FIG. 6A shows that the number of the indoor units A to D to be operated is sequentially increased one by one. FIGS. 6B to 6E show the opened and closed states of the expansion valves 23 of the indoor units A to D, respectively. When the indoor units A~D starts operation, each predetermined time (in this case, is set equal to the force operating time t ₂₎ as in shown in FIG. 6 (g) operation start signal is generated.

The gas burner 15a of the outdoor unit 10
As shown in FIG. 6 (h), the gas is burned intermittently according to the thermal energy to be supplied to the indoor unit 20 (actually, the temperature and pressure inside the outdoor unit 10), and the gas burner 15a is extinguished. The period of time becomes shorter as the number of operating indoor units 20 increases (in the illustrated example, when four indoor units A to D are operated, a continuous combustion state occurs). If the number of operating indoor units 20 does not change, the combustion time of the gas burners 15a is determined according to the total load of the indoor units 20, but immediately after the number of operating indoor units 20 increases, the gas burners 15a
If the combustion time is shorter than the forced operation time t ₂ if the combustion is already burning and the combustion time determined by the total load of the indoor unit 20 is shorter than the forced operation time t _2
2 keeps the combustion state. That is, the gas burner 15a
The time period of the forced operation time t ₂ starts with the start of combustion of
If the above-mentioned operation start signal is not generated, the forced operation time t
The ₂ controls the gas burner 15a regardless when the operation start signal is generated until the end of the forced operation time t ₂ to continue the combustion of the gas burner 15a. In addition, the indoor unit 20
Combustion time determined by the total load of
₂ forced operation time t ₂ to continue the combustion of the gas burner 15a be completed is longer than.

On the other hand, the control of the expansion valve 23 of the indoor unit 20 is prohibited when the combustion of the gas burner 15a of the outdoor unit 10 is stopped. This is because, when the expansion valve 23 is controlled in a state where heat energy is not supplied from the outdoor unit 10, the refrigerant in the pump 30 is gasified without applying an appropriate pressure to the refrigerant, or the indoor unit 20 This is because the amount of heat supplied to the heater may be insufficient. The state in which the control of the expansion valve 23 is prohibited is the valve control prohibition mode, and the valve control prohibition mode may be released when the gas burner 15a of the outdoor unit 10 is burning. Then
Prohibition time t ₁ from the start of combustion gas burner 15a as shown in FIG. 6 (f) are extended valve control inhibit mode. The time extension of the valve control prohibition mode is performed every time the gas burner 15a starts combustion regardless of whether the number of operating indoor units 20 increases. As a result, the expansion valve 23 is not controlled until the time when the heat energy is supplied to the indoor unit 20 from the start of combustion of the gas burner 15a in the outdoor unit 10 has elapsed. When the valve 23 is opened, the load fluctuation of the outdoor unit 10 can be suppressed. That is, gasification of the refrigerant inside the path (refrigerant liquid pipe 31) from the pump 30 to the outdoor unit 10 can be suppressed, and the gas of the refrigerant in the pump 30 when the number of operating indoor units 20 increases is increased. Can be prevented.

By controlling the expansion valve 23 as described above, the expansion valve 23 of each of the indoor units A to D can be controlled as shown in FIGS.
It is opened and closed as shown in (e), and the expansion valve 23 of the indoor unit A is kept open as shown in FIG.
Expansion valve of the indoor unit B as shown in FIG. 6 (c) 23 is opened after the elapse of the inhibition time t ₁ from the instruction of operation start of the indoor unit B (the rise of the operation start signal).

In the illustrated example, the operation of the indoor unit C is instructed while the operation of the indoor unit B is started and the gas burner 15a of the outdoor unit 10 is burning. In this case, the operation of the indoor unit C is instructed. At this time, the gas burner 15a is burning, and the combustion of the gas burner 15a is continued.
Also, the forced operation time t from the start of combustion of the gas burner 15a.
_{Since the} load on the outdoor unit 10 does not reach the value even after ₂ has elapsed, the combustion of the gas burner 15a is further continued. On the other hand, the expansion valve 23 of the indoor unit C is connected to the gas burner 15a.
Is from the start of combustion being released after a prohibition time t _1, as shown in FIG. 6 (d), the from the operating instructions of the indoor unit C to the opening of the expansion valve 23 will be slightly delayed.

[0028] have been instructed during combustion operation initiated burner 15a of the indoor unit D, from the operation start time of the indoor unit D has become after a lapse of a prohibition time t ₁ from the start of combustion gas burner 15a, the In this case, the instruction to start the operation of the indoor unit D is issued during a period other than the valve control prohibition mode, and the expansion valve 23 is opened at the same time as the instruction to start the operation of the indoor unit D as shown in FIG. Is done. In addition, the gas burner 15a always keeps burning.

By the above operation, the combustion of the gas burner 15a of the outdoor unit 10 is started before the expansion valve 23 is opened, the internal pressure of the refrigerant gas pipe 32 is increased, and the pressure drop accompanying the opening of the expansion valve 23 is reduced. The gas burner 1 of the outdoor unit 10 can be suppressed when the number of operating indoor units 20 increases.
By always burning 5a, a decrease in the internal pressure of the refrigerant gas pipe 32 due to an increase in load can be suppressed. As a result, it is possible to prevent the refrigerant inside the pump 30 from being gasified and to operate normally even when the load changes.

Other configurations and operations are the same as those of the conventional configuration.

[0031]

According to the first aspect of the present invention, a plurality of indoor units are provided, and operation monitoring means for detecting the number of operating indoor units is provided, and when the increase in the number of operating indoor units is detected by the operation monitoring means, If the combustion means is not burning, the combustion is started.If the operation monitoring means detects an increase in the number of operating indoor units, the outdoor unit is configured to continue the combustion of the combustion means for a certain forced operation time from the start of combustion. When the number of operating indoor units increases, the combustion means of the outdoor units always burn, so when the number of operating indoor units increases, the refrigerant is vaporized by the outdoor units to maintain the pressure, There is an advantage that the pressure in the path from the unit to the indoor unit can be prevented from suddenly decreasing. Moreover, when the operation of the indoor unit is started, the combustion is continued for a certain forced operation time from the start of combustion of the combustion means, so that the pressure sufficient to increase the number of operating indoor units can be maintained, and It is possible to prevent the refrigerant in the pump from being vaporized due to a large pressure drop, and there is an advantage that the pump can be normally operated even if the number of operating indoor units suddenly increases.

A second aspect of the present invention provides a coil unit for exchanging heat between a refrigerant and a room in an indoor unit, an expansion valve for selecting a state of permitting or prohibiting the passage of the refrigerant through the coil unit, and a coil. A temperature sensor that detects the temperature of the refrigerant before and after the unit, and a controller that opens and closes the expansion valve so as to keep the temperature difference of the temperature sensor substantially at a set value,
A certain prohibition time from the start of combustion of the combustion means of the outdoor unit prohibits the opening and closing of the expansion valve by the controller, and a certain prohibition time from the start of combustion of the combustion means of the outdoor unit prohibits the opening and closing of the expansion valve. The expansion valve is not opened or closed until the pressure of the path from the outdoor unit to the indoor unit is increased to a certain degree after the combustion of the combustion unit of the outdoor unit is started, thereby preventing a sudden pressure drop due to the opening of the expansion valve. It has advantages.

A third aspect of the present invention provides a coil unit for exchanging heat between a refrigerant and a room in an indoor unit, an expansion valve for selecting a state of permitting or prohibiting the passage of the refrigerant through the coil unit, and a coil. A temperature sensor that detects the temperature of the refrigerant before and after the unit, and a controller that opens and closes the expansion valve so as to keep the temperature difference of the temperature sensor substantially at a set value,
A plurality of indoor units are provided and operation monitoring means for detecting the number of operating indoor units is provided, and when the increase in the number of operating indoor units is detected by the operation monitoring means, combustion is started unless the combustion means is burning. When the increase in the number of operating indoor units is detected by the operation monitoring unit, the outdoor unit is controlled so that the combustion unit continues to burn for a certain forced operation time from the start of combustion, and the combustion unit of the outdoor unit starts burning. Since the controller prohibits the controller from opening and closing the expansion valve for a certain prohibition time, both the outdoor unit and the indoor unit cope with the pressure drop due to the opening of the expansion valve of the indoor unit, so the refrigerant in the pump is gasified. Can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is a view for explaining the principle of the outdoor unit used in the embodiment.

FIG. 4 is a configuration diagram of an outdoor unit used in the embodiment.

FIG. 5 is an operation explanatory view of the above.

FIG. 6 is an operation explanatory view of the above.

FIG. 7 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 10 outdoor unit 15a gas burner 20 indoor unit 21 coil unit 23 expansion valve 30 pump 40 control circuit 24a, 24b temperature sensor 25 controller

Claims (3)

[Claims] An outdoor unit for evaporating a refrigerant by using heat energy generated by combustion of a combustion unit is provided. The refrigerant vaporized by the outdoor unit is condensed by the indoor unit, and the condensed refrigerant is transmitted to the outdoor unit via a pump. In the returning air conditioning system, a plurality of indoor units are provided and operation monitoring means for detecting the number of operating indoor units is provided, and the combustion means must not be burning when the increase in the number of operating indoor units is detected by the operation monitoring means. If combustion is started, and the operation monitoring means detects an increase in the number of operating indoor units, the outdoor unit is controlled so as to continue combustion of the combustion means for a fixed forced operation time from the start of combustion. Air conditioning system. 2. An outdoor unit for vaporizing a refrigerant using heat energy generated by combustion of a combustion means, condensing the refrigerant vaporized by the outdoor unit in the indoor unit, and condensing the refrigerant into the outdoor unit via a pump. In the returning air conditioning system, the indoor unit has a coil unit that exchanges heat between the refrigerant and the room, an expansion valve that selects a state in which the passage of the refrigerant through the coil unit is permitted or prohibited, and a refrigerant in front and behind the coil unit. And a controller for opening and closing the expansion valve so as to keep the temperature difference of the temperature sensor substantially at a set value, and the controller controls the expansion valve for a certain prohibition time from the start of combustion of the combustion means of the outdoor unit. An air-conditioning system characterized by prohibiting opening and closing of air conditioners. 3. An outdoor unit for vaporizing a refrigerant using heat energy generated by combustion of the combustion means, condensing the refrigerant vaporized by the outdoor unit in the indoor unit, and condensing the refrigerant to the outdoor unit via a pump. In the returning air conditioning system, the indoor unit has a coil unit that exchanges heat between the refrigerant and the room, an expansion valve that selects a state in which the passage of the refrigerant through the coil unit is permitted or prohibited, and a refrigerant in front and behind the coil unit. Operation monitoring means for providing a plurality of indoor units and detecting the number of operating indoor units, provided with a temperature sensor for detecting the temperature of the air conditioner, and a controller for opening and closing the expansion valve so as to keep the temperature difference between the temperature sensors substantially at a set value. If the combustion unit is not burning when the increase in the number of operating indoor units is detected by the operation monitoring unit, the combustion is started, and the operation monitoring unit increases the number of operating indoor units. Is detected, the outdoor unit is controlled so as to continue the combustion of the combustion means for a certain forced operation time from the start of combustion, and the expansion valve is opened and closed by the controller for a certain prohibition time from the start of combustion of the combustion means of the outdoor unit. Air-conditioning system characterized by prohibition.