JP2006170497A - Refrigerant natural circulation type cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly start cooling operation without impairing economic efficiency by minimizing the frequency of opening and closing an electronic expansion valve in performing the cooling operation by starting a part of a plurality of indoor units. <P>SOLUTION: The temperature difference between supply air temperature and return air temperature to a use-side heat exchanger is calculated by a temperature difference calculating means 16 after starting the cooling operation, the inability to start is judged when the temperature difference is not agreed with steady transition temperature difference which is judged to be a state transitable to a steady cooling operation state, even after the lapse of a set time from the starting, a start inability signal is output from a start inability discriminating means 19, an indoor unit in a cooling operation stop state is selected by a support indoor unit selecting means 20, and a start supporting signal is output to open the electronic expansion valve 7 of the corresponding indoor unit. Thus the refrigerant gas is released from a refrigerant liquid pipe in an early stage by utilizing the indoor unit in the cooling operation stop state, and the starting is performed and transited to the cooling operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a natural refrigerant circulation in which cooling is performed by flowing a refrigerant that changes phase between gas and liquid by natural circulation between a condenser and a use-side heat exchanger provided in a plurality of indoor units. The present invention relates to a type cooling system.

  In the refrigerant natural circulation type cooling system as described above, there is a problem that it takes time until the temperature-controlled air at a predetermined temperature is actually blown when the indoor unit is started. This is because the refrigerant gas is generated and accumulated in the refrigerant liquid pipe while the cooling operation is stopped, and the natural refrigerant circulation is impaired by the accumulated refrigerant gas, and the refrigerant gas escapes from the refrigerant liquid pipe. This is because it takes time.

Therefore, in order to eliminate the above-described problems, conventionally, there are the following methods for removing the refrigerant gas mixed in the refrigerant liquid pipe.
A pressure sensor that measures the pressure in the refrigerant liquid pipe is provided near the entrance to the indoor unit (indoor unit) located at the lowest position, and the pressure in the refrigerant liquid pipe is monitored while the cooling operation is stopped. The expansion valve is opened when the measured pressure becomes lower than a predetermined pressure, and the refrigerant gas generated in the refrigerant liquid pipe is extracted (see Patent Document 1).

Further, the pressure difference between the pressure in the supply pipe for supplying the refrigerant to the heat exchanger of the indoor air conditioner (indoor unit) and the pressure in the return pipe is obtained, and when the pressure difference becomes a certain value or less, the heat exchanger An electromagnetic valve for controlling the amount of refrigerant supplied to the engine is opened, and the refrigerant gas accumulated in the supply pipe is discharged to the return pipe (see Patent Document 2).
JP 2000-292025 A JP-A-7-151353

  However, in the case of the former conventional example as described above, the cooling operation is performed only for a short time in some of the plurality of indoor units, such as in the intermediate period or winter period, and the cooling operation is stopped. Even in such a case, when the refrigerant gas accumulates, the expansion valve to the indoor unit (indoor unit) located at the lowest position is opened. Thus, when the frequency of opening and closing the expansion valve is high, there is a drawback that even if a specific expansion valve is used, the expansion valve is likely to be damaged at an early stage, and maintenance and inspection are troublesome and expensive, resulting in a reduction in economic efficiency. In addition, even when the expansion valve is opened and closed, if an activation failure occurs in the indoor unit to be activated, it is immediately judged as an activation failure and maintenance is required, and there is a disadvantage that the economy is similarly reduced. It was.

  In the latter conventional example, the solenoid valves of all the plurality of indoor units are opened and closed, and there is a disadvantage that the economic efficiency is further reduced as compared with the former conventional example.

  The present invention has been made in view of the above points, and the invention according to claims 1 and 2 is directed to an electronic expansion valve when a part of a plurality of indoor units is activated to perform a cooling operation. An object of the invention according to claim 3 is to find out abnormalities of the refrigerant circulation system at an early stage, and to prevent troubles from occurring, with the aim of reducing the frequency of opening and closing as much as possible so that it can be started up satisfactorily without reducing the economic efficiency. The inventions according to claims 4 and 5 are intended to make it possible to effectively eliminate startup failures.

In order to achieve the above-described object, the invention according to claim 1
A plurality of indoor units including use side heat exchangers that evaporate and evaporate a refrigerant that changes phase between gas and liquid and dissipate cold heat are provided, and the use side heat exchanger and a condenser that condenses and liquefies the refrigerant are provided. The refrigerant liquid pipe and the refrigerant gas pipe are connected to each other, the condenser is disposed above the use side heat exchanger, and the natural heat circulates between the condenser and the use side heat exchanger. The refrigerant liquid pipe is provided with a head difference sufficient to transfer the refrigerant liquid condensed and liquefied by the condenser to the use side heat exchanger and to transfer the refrigerant gas evaporated and evaporated by the use side heat exchanger to the condenser. In the refrigerant natural circulation type cooling system provided with an electronic expansion valve for adjusting the amount of refrigerant liquid supplied to the use side heat exchanger,
A supply air temperature sensor for measuring a supply air temperature of the temperature-controlled air blown out from the use side heat exchanger;
A return air temperature sensor for measuring the return air temperature of the temperature-controlled air returned to the use side heat exchanger;
A temperature difference calculating means for calculating a difference between the return air temperature measured by the return air temperature sensor and the supply air temperature measured by the supply air temperature sensor;
Comparing means for outputting a steady cooling operation transition signal when the temperature difference calculated by the temperature difference calculation means becomes a steady transition temperature difference that can be determined to be a state capable of transitioning to the steady cooling operation state;
An opening degree control means for switching the opening degree of the electronic expansion valve to a required opening degree in a steady cooling operation state in response to a steady cooling operation transition signal from the comparison means after starting the cooling operation;
Even if the set time has elapsed after the start of cooling operation, a start impossible signal is output when the temperature difference calculated by the temperature difference calculating means does not become a steady transition temperature difference that can be determined to be a transition to the steady cooling operation state. A non-startable discrimination means to
In response to the start disable signal from the start disable determination means, a high priority indoor unit is selected from the indoor units excluding the indoor unit scheduled to start and the indoor unit in the cooling operation state. Supporting indoor unit selection means for outputting an activation support signal to the indoor unit and opening an electronic expansion valve of the corresponding indoor unit.
Here, the “indoor unit scheduled to start” refers to an indoor unit that is about to start the cooling operation. In addition, the “indoor unit excluding the indoor unit scheduled to start and the indoor unit in the cooling operation state” is not limited to the indoor unit that has stopped operating, but the indoor unit that is operating in the ventilation mode, and In the case of an indoor unit that also performs heating, the indoor unit that is operating in the heating mode is also included (hereinafter, the same as the indoor unit that is in the cooling operation stop state).

  The steady-state transition temperature difference varies depending on the mounting position of the temperature sensor and whether the responsiveness is good or bad. When the temperature difference (for example, 10 ° C.) in the steady-state cooling operation state is T, the temperature difference is 25-50. % (0.25-0.5T). If it is less than 25%, the escape of the refrigerant gas becomes insufficient, and if it exceeds 50%, the refrigerant liquid tends to flow into the refrigerant gas pipe before the transition to the steady cooling operation state, so that a so-called liquid back is likely to occur. is there.

(Action / Effect)
According to the configuration of the refrigerant natural circulation type cooling system of the invention according to claim 1, the cooling operation is started, and the temperature difference calculated by the temperature difference calculating means can be shifted to the steady cooling operation state even if the set time has elapsed. It is determined that it is impossible to start when the steady transition temperature difference that can be determined as the state is not reached, and the indoor unit excluding the indoor unit scheduled to start and the indoor unit in the cooling operation state, that is, among the indoor units in the cooling operation stopped state The electronic expansion valve of the indoor unit having a high priority is opened, and the diameter of the refrigerant liquid pipe that draws the refrigerant gas in the refrigerant liquid pipe to the refrigerant gas pipe side is substantially enlarged so that the refrigerant gas can be easily released.

Therefore, since the electronic expansion valve of the indoor unit in the cooling operation stop state is opened only when the cooling operation is started, the electronic expansion valve is frequently used even though the frequency of the cooling operation is low, such as in the intermediate period or winter period. Compared to the conventional case of opening / closing the cooling operation, the cooling operation can be started by opening and closing the electronic expansion valve to the minimum necessary. In addition, since the start-up is promoted by using the indoor unit in the cooling operation stop state, when the cooling operation is performed by starting a part of the plurality of indoor units, the opening / closing frequency of the electronic expansion valve is reduced as much as possible. It can start well without degrading economy.
In addition, based on the temperature difference between the supply air temperature and the return air temperature of the temperature-controlled air blown from the use side heat exchanger, whether or not the refrigerant starts natural circulation and can shift to the steady cooling operation state. Therefore, an inexpensive temperature sensor can be used, and the economy can be improved in this respect.

In order to achieve the above-described object, the invention according to claim 2
A plurality of indoor units including use side heat exchangers that evaporate and evaporate a refrigerant that changes phase between gas and liquid and dissipate cold heat are provided, and the use side heat exchanger and a condenser that condenses and liquefies the refrigerant are provided. The refrigerant liquid pipe and the refrigerant gas pipe are connected to each other, the condenser is disposed above the use side heat exchanger, and the natural heat circulates between the condenser and the use side heat exchanger. The refrigerant liquid pipe is provided with a head difference sufficient to transfer the refrigerant liquid condensed and liquefied by the condenser to the use side heat exchanger and to transfer the refrigerant gas evaporated and evaporated by the use side heat exchanger to the condenser. In the refrigerant natural circulation type cooling system provided with an electronic expansion valve for adjusting the amount of refrigerant liquid supplied to the use side heat exchanger,
An inlet side pressure sensor for measuring an inlet side pressure in the refrigerant liquid pipe on the upstream side of the electronic expansion valve;
An outlet-side pressure sensor that measures an outlet-side pressure in the refrigerant gas pipe on the downstream side of the use-side heat exchanger;
Pressure difference calculating means for calculating a difference between an inlet side pressure measured by the inlet side pressure sensor and an outlet side pressure measured by the outlet side pressure sensor;
Comparison means for outputting a steady cooling operation transition signal when the pressure difference calculated by the pressure difference calculation means becomes a steady transition pressure difference that can be determined as a state capable of transitioning to the steady cooling operation state;
An opening degree control means for switching the opening degree of the electronic expansion valve to a required opening degree in a steady cooling operation state in response to a steady cooling operation transition signal from the comparison means after starting the cooling operation;
Even if a set time elapses after the start of cooling operation, an unsuccessful start signal is output when the pressure difference calculated by the pressure difference calculation means does not become a steady transition pressure difference that can be determined to be a transition to the steady cooling operation state. A non-startable discrimination means to
In response to the start disable signal from the start disable determination means, the indoor unit selected by selecting a high priority indoor unit among the indoor units excluding the indoor unit scheduled to start and the indoor unit in the cooling operation state. Supporting indoor unit selection means for outputting an activation support signal to the unit and opening the electronic expansion valve of the corresponding indoor unit.

  The steady transition pressure difference varies depending on the mounting position of the pressure sensor and whether the responsiveness is good or bad. When the pressure difference in the steady cooling operation state is P, the difference is 25 to 50% (0.25 to 0.25%). 0.5P). If it is less than 25%, the escape of the refrigerant gas becomes insufficient, and if it exceeds 50%, the refrigerant liquid tends to flow into the refrigerant gas pipe before the transition to the steady cooling operation state, so that a so-called liquid back is likely to occur. is there.

(Action / Effect)
According to the configuration of the refrigerant natural circulation type cooling system of the invention according to claim 2, the cooling operation is started, and the pressure difference calculated by the pressure difference calculating means can be shifted to the steady cooling operation state even if the set time has elapsed. It is determined that it is impossible to start when the steady transition temperature difference that can be determined as the state is not reached, and the indoor unit excluding the indoor unit scheduled to start and the indoor unit in the cooling operation state, that is, among the indoor units in the cooling operation stopped state The electronic expansion valve of the indoor unit having a high priority is opened, and the diameter of the refrigerant liquid pipe that draws the refrigerant gas in the refrigerant liquid pipe to the refrigerant gas pipe side is substantially enlarged so that the refrigerant gas can be easily released.

  Therefore, since the electronic expansion valve of the indoor unit in the cooling operation stop state is opened only when the cooling operation is started, the electronic expansion valve is frequently used even though the frequency of the cooling operation is low, such as in the intermediate period or winter period. Compared to the conventional case of opening / closing the cooling operation, the cooling operation can be started by opening and closing the electronic expansion valve to the minimum necessary. In addition, since the start-up is promoted by using the indoor unit in the cooling operation stop state, when the cooling operation is performed by starting a part of the plurality of indoor units, the opening / closing frequency of the electronic expansion valve is reduced as much as possible. It can start well without degrading economy.

In order to achieve the above-described object, the invention according to claim 3
In the refrigerant natural circulation type cooling system according to claim 1 or 2,
An abnormality determination that outputs an abnormality signal when the activation disable signal is received from the activation disable determination means even after the activation support signal is output to all of the corresponding indoor units from the support indoor unit selection means and the support operation is completed. A means is provided.

(Action / Effect)
According to the configuration of the refrigerant natural circulation type cooling system of the invention according to claim 3, it is determined that an abnormality cannot be started even if the electronic expansion valves of all indoor units in the cooling operation stop state are opened, and this is indicated by an abnormal signal. Can output and inform.
Therefore, abnormalities in the refrigerant circulation system such as refrigerant leakage and malfunction of the electronic expansion valve can be found at an early stage, and trouble can be prevented.

In order to achieve the above-described object, the invention according to claim 4
In the refrigerant natural circulation type cooling system according to any one of claims 1, 2, and 3,
Install indoor units at different heights in the vertical direction,
The support indoor unit selection means is configured to be set so that the lower the indoor unit in the lower position, the higher the priority.

(Action / Effect)
According to the configuration of the refrigerant natural circulation type cooling system of the invention according to claim 4, among the indoor units in the cooling operation stop state, the indoor unit in the low position, that is, the length of the refrigerant liquid pipe from the condenser is Preferentially open electronic expansion valves for long indoor units.
Accordingly, since the refrigerant gas can be extracted from the refrigerant liquid piping of the portion where the refrigerant liquid piping is long and the amount of the refrigerant gas accumulated is large, the refrigerant gas can be quickly discharged and the starting failure can be effectively eliminated.

Further, in order to achieve the above-described object, the invention according to claim 5
In the refrigerant natural circulation cooling system according to any one of claims 1, 2, 3, and 4,
An indoor unit is installed in a state where the distance is different in the horizontal direction in the refrigerant liquid pipe in the vertical direction,
The support indoor unit selection means is configured to be set so that the priority is higher in the indoor unit located farther from the vertical refrigerant liquid pipe.

(Action / Effect)
According to the configuration of the refrigerant natural circulation type cooling system of the invention according to claim 5, among the indoor units in the cooling operation stop state, the indoor unit located far from the vertical refrigerant liquid pipe, that is, the vertical refrigerant. The electronic expansion valve of the indoor unit with a long refrigerant liquid pipe from the liquid pipe is preferentially opened.
Accordingly, since the refrigerant gas can be extracted from the refrigerant liquid piping of the portion where the refrigerant liquid piping is long and the amount of the refrigerant gas accumulated is large, the refrigerant gas can be quickly discharged and the starting failure can be effectively eliminated.

  According to the configuration of the refrigerant natural circulation type cooling system of the invention according to claim 1, the cooling operation is started, and the temperature difference calculated by the temperature difference calculating means can be shifted to the steady cooling operation state even if the set time has elapsed. It is determined that it is impossible to start when the steady transition temperature difference that can be determined as the state is not reached, and the indoor unit excluding the indoor unit scheduled to start and the indoor unit in the cooling operation state, that is, among the indoor units in the cooling operation stopped state The electronic expansion valve of the indoor unit having a high priority is opened, and the diameter of the refrigerant liquid pipe that draws the refrigerant gas in the refrigerant liquid pipe to the refrigerant gas pipe side is substantially enlarged so that the refrigerant gas can be easily released.

Therefore, since the electronic expansion valve of the indoor unit in the cooling operation stop state is opened only when the cooling operation is started, the electronic expansion valve is frequently used even though the frequency of the cooling operation is low, such as in the intermediate period or winter period. Compared to the conventional case of opening / closing the cooling operation, the cooling operation can be started by opening and closing the electronic expansion valve to the minimum necessary. In addition, since the start-up is promoted by using the indoor unit in the cooling operation stop state, when the cooling operation is performed by starting a part of the plurality of indoor units, the opening / closing frequency of the electronic expansion valve is reduced as much as possible. It can start well without degrading economy.
In addition, based on the temperature difference between the supply air temperature and the return air temperature of the temperature-controlled air blown from the use side heat exchanger, whether or not the refrigerant starts natural circulation and can shift to the steady cooling operation state. Therefore, an inexpensive temperature sensor can be used, and the economy can be improved in this respect.

  Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram showing a refrigerant natural circulation cooling system according to a first embodiment of the present invention, and a plurality of indoor units 1 having different cooling capabilities are installed on each floor of a building.
The indoor unit 1 evaporates and evaporates a refrigerant that changes phase between gas and liquid to dissipate cold heat, and blows air that sucks in air from the room and passes through the use side heat exchanger 2 to blow it out. The fan 3 is provided.

A condenser 4 for condensing and liquefying the refrigerant is provided at a position above the indoor unit 1 on the top floor, and the condenser 4 and the use side heat exchanger 2 are connected via a refrigerant liquid pipe 5 and a refrigerant gas pipe 6. It is connected.
The refrigerant liquid condensed and liquefied by the condenser 4 is transferred to the utilization side heat exchanger 2 by natural circulation between the condenser 4 and the utilization side heat exchanger 2 and evaporated by the utilization side heat exchanger 2. A head difference sufficient to transfer the refrigerant gas to the condenser 4 is provided.

An electronic expansion valve 7 that adjusts the amount of refrigerant liquid supplied to the usage-side heat exchanger 2 is provided at a location near the usage-side heat exchanger 2 in the refrigerant liquid piping 5.
The electronic expansion valve 7 is selected to have an opening that can be opened more than 1.5 times the maximum opening required in the steady cooling operation state (specified according to the air conditioning (cooling) capacity of the indoor unit 1). ing.

  In the indoor unit 1, as shown in the enlarged view of FIG. 2, the supply temperature of the temperature-controlled air blown from the use-side heat exchanger 2 is measured downstream of the temperature-controlled air of the use-side heat exchanger 2. A supply air temperature sensor 8 is provided, and a return air temperature sensor 9 for measuring the return air temperature of the temperature adjustment air returned to the use side heat exchanger 2 is provided upstream of the temperature adjustment air of the blower fan 3. .

  In addition, a first refrigerant temperature sensor 10 that measures the refrigerant temperature is provided at a location near the entrance to the use side heat exchanger 2 of the refrigerant liquid pipe 5, while from the use side heat exchanger 2 of the refrigerant gas pipe 6. The 2nd refrigerant | coolant temperature sensor 11 which measures a refrigerant | coolant temperature in the location near the exit of this is provided.

  Each indoor unit 1 is provided with a controller 12, while a central controller 13 is provided with a main controller 13. Each controller 12 is connected to the main controller 13, the supply air temperature sensor 8, the return air temperature sensor 9, the first and second refrigerant temperature sensors 10, 11 are connected to the controller 12, and an electronic expansion valve is connected to the controller 12. 7, and an operation switch 14 for each indoor unit 1 and a timer 15 that is reset in response to a cooling operation start signal from the operation switch 13 and that outputs a time signal after a set time has elapsed. Has been.

  As shown in the block diagram of the control system of FIG. 3, the controller 12 is provided with a temperature difference calculating means 16, a comparing means 17, an opening degree controlling means 18, and a start impossible determining means 19. The main controller 13 includes a support indoor unit selection unit 20, a priority order setting table 21, and an abnormality determination unit 22, and an alarm lamp 23 is connected to the main controller 13.

The temperature difference calculating means 16 calculates the difference between the return air temperature measured by the return air temperature sensor 9 and the supply air temperature measured by the supply air temperature sensor 8.
The comparison means 17 compares the temperature difference calculated by the temperature difference calculation means 16 with the set value (0.3T). When the calculated temperature difference is not equal to or greater than the set value, an unstart signal is output, and the calculated temperature difference is A steady cooling operation transition signal is output when the set value is exceeded.

  Here, as the set value (0.3T), a steady transition temperature difference that can be determined as a state in which the transition to the steady cooling operation state can be made is set. More specifically, a value of 30% (0.3 T) is set for the temperature difference T (usually about 10 ° C.) in the steady cooling operation state. As this setting value, a value of 25 to 50% may be set. This is because the temperature difference after the operation is a result indicating that the refrigerant gas has escaped and the refrigerant liquid has started to flow and be supplied to the use-side heat exchanger 2. This is because it can be determined that the state is to be performed.

  In the opening degree control means 18, the opening degree of the electronic expansion valve 7 is opened to a possible opening degree in response to the cooling operation start signal from the operation switch 14, and the steady cooling operation transition signal from the temperature difference calculation means 14 is set. In response, the opening degree of the electronic expansion valve 7 is switched to a necessary opening degree in the steady cooling operation state.

  In the start impossible determination means 19, when the time signal from the timer 15 is received, the temperature difference calculation means when the non-start signal is received from the temperature difference calculation means 16, that is, even if the set time elapses after starting the cooling operation. When the temperature difference calculated in 16 does not become a steady transition temperature difference that can be determined to be a state in which the transition to the steady cooling operation state can be made, an unstartable signal is output.

  In the support indoor unit selection means 20, in response to the start disable signal from the start disable determination means 19, the indoor unit 1 scheduled to start up and the cooling based on the cooling operation start signal from the operation switch 14 from the priority order setting table 21. Among the indoor units 1 excluding the indoor unit 1 in the operating state, the indoor unit 1 having a higher priority is selected, a start support signal is output to the selected indoor unit 1, and the electronic expansion of the corresponding indoor unit 1 is performed. The valve 7 is opened to a possible opening.

  In the priority order setting table 21, the indoor unit 1 at a position where the height is different in the vertical direction is set in advance so that the priority is higher in the indoor unit 1 at the lower position, and the refrigerant liquid piping in the vertical direction is set. For the indoor unit 1 in a state where the distance is different in the horizontal direction, the indoor unit 1 located farther from the refrigerant liquid pipe 5 in the vertical direction is set in advance so that the priority is higher. As a result, the indoor unit 1 that is at a low position and far from the refrigerant liquid pipe 5 in the vertical direction among the indoor units 1 excluding the indoor unit 1 scheduled to be activated and the indoor unit 1 in the cooling operation state is selected by the support indoor unit selection means 20. 1 is selected in order. When there are a plurality of indoor units 1 at different positions in the vertical direction and a plurality of indoor units 1 at positions far from the refrigerant liquid pipe 5 in the vertical direction, the indoor unit 1 at the lower position is given priority.

  The abnormality determination unit 22 receives a start disable signal from the start disable determination unit 19 after outputting a start support signal to all the corresponding indoor units 1 from the support indoor unit selection unit 20 and completing the support operation. An abnormality signal is output to the alarm lamp 23, and the alarm lamp 23 blinks to notify the abnormality.

Next, the control operation will be described with reference to the flowchart of FIG.
First, it is determined whether the operation switch 14 is turned on and an operation signal is output (S1).
If the operation signal is output, it will transfer to step S2 and operation control, such as driving the ventilation fan 3, will be performed. If no operation signal is output, the process returns to step S1.

Next, it is determined whether or not the operation mode is a cooling mode (S3).
If it is not in the cooling mode, it shifts to another operation mode such as a heating mode or a ventilation mode. If it is in the cooling mode, the opening of the electronic expansion valve 7 is opened to a possible opening, and then the process proceeds to step S4, where it is determined whether the temperature difference ΔT is equal to or greater than the set temperature difference, that is, whether it is activated.

  If it is determined in step S4 that the temperature difference ΔT is not greater than or equal to the set temperature difference, that is, it has not been started, the process proceeds to step S5 to determine whether the set time has elapsed, and within the set time, the temperature difference When ΔT is equal to or greater than the set temperature difference, that is, when it is determined that it has been started, the routine proceeds to step S6, where steady control is performed, and the opening of the electronic expansion valve 7 is switched to the required opening in the steady cooling operation state. .

  When it is determined in step S5 that the set time has elapsed, that is, when it is determined that the activation is impossible, an activation impossible signal is output, and the process proceeds to step S7 to perform activation control. That is, the activation support indoor unit selection means 20 selects the indoor unit 1 having a higher priority among the indoor units 1 excluding the indoor unit 1 scheduled to be activated and the indoor unit 1 in the cooling operation state, and is selected. An activation support signal is output to the indoor unit 1 and the electronic expansion valve 7 of the corresponding indoor unit 1 is opened to the openable opening. Thereafter, it is determined whether or not the temperature difference ΔT is equal to or greater than the set temperature difference, that is, whether the temperature difference ΔT is activated (S8). When the temperature difference ΔT is equal to or greater than the set temperature difference within the set time (S9), that is, activated When it is determined that the operation has been performed, the routine proceeds to step S6, where steady control is performed, and the opening of the electronic expansion valve 7 is switched to a required opening in the steady cooling operation state.

  In step S9, when it is determined that the set time has elapsed, that is, when it is determined that the activation is impossible, an activation impossible signal is output, and the process proceeds to step S10 where all the indoor units 1 are detected by the activation support indoor unit selecting means 20. It is determined whether or not it has been selected. If not all, the process proceeds to start control (S7), the indoor unit 1 having the next highest priority is selected, and a start support signal is output to the selected indoor unit 1. The electronic expansion valve 7 of the corresponding indoor unit 1 is opened to the openable opening.

  If it is determined by the abnormality determination means 22 that all the indoor units 1 are selected and the activation control is performed, it is determined that the activation is impossible, the process proceeds to step S11, the alarm lamp 23 blinks, and the refrigerant leakage such as the refrigerant leakage occurs. Notify that there is an abnormality in the natural circulation system.

  With the above configuration, when the cooling operation cannot be started even after the set time has elapsed, the refrigerant gas is quickly extracted from the refrigerant liquid pipe 5 by using the indoor unit 1 in the cooling operation stop state. It is possible to shift to cooling operation. Further, if it is impossible to start even if all the indoor units 1 are selected and the start control is performed, an abnormality is notified and repair or the like is prompted.

Although not shown, the controller 12 controls the opening of the electronic expansion valve 7 in the steady cooling operation state based on the refrigerant temperatures measured by the first and second refrigerant temperature sensors 10 and 11. It has become.
In other words, the refrigerant temperature difference between the refrigerant temperature measured by the second refrigerant temperature sensor 11 and the refrigerant temperature measured by the first refrigerant temperature sensor 10 is calculated, and the refrigerant temperature difference is a first set value (for example, 4) When the following is true, the opening degree of the electronic expansion valve 7 is closed by a set amount, and when the refrigerant temperature difference is a second set value (for example, 10) or more, the opening degree of the electronic expansion valve 7 is opened by a set amount, and When the refrigerant temperature difference is between the first set value and the second set value, the opening degree of the electronic expansion valve 7 is maintained as it is, and the temperature-controlled air at the set temperature can be always blown out. It is designed to perform cooling operation.

  As the electronic expansion valve 7, a valve whose opening-refrigerant flow rate characteristics are close to linear is used. As a result, the refrigerant gas in the refrigerant liquid pipe 5 can be quickly extracted when the one having a sufficient margin such that the required maximum opening is three times or more in the steady cooling operation state can be quickly extracted. It can be done more effectively.

Further, at the time of a start-up test after the indoor unit 1 is carried in, for example, the opening degree of the electronic expansion valve 7 is doubled, and the time until the temperature difference calculating means 14 exceeds the set temperature difference is measured. If the time is long, the opening degree is adjusted to 4 times, and if the time is still long, the opening degree is adjusted to 8 times, so that the openable opening degree can be set so as to shorten the time as much as possible.
As a result, regardless of the maximum opening required for the electronic expansion valve for controlling the refrigerant liquid in the steady cooling operation state, at the time of start-up, the maximum opening of the selected electronic expansion valve itself is set as an openable opening. Gas can be flowed with less resistance, and degassing can be performed more rapidly.

In addition, when it is necessary to suppress the generation of a large flow noise such as surreal due to a large amount of refrigerant flowing in the piping, such as in a hotel, the selected electronic expansion valve itself Even if the maximum opening is large, the openable opening is set to an opening that is close to 1.5 times the maximum opening required in the steady cooling operation state, and the time as much as possible is taken into account while taking into account the loudness of the flow noise. Degassing can be quickly performed by setting the opening degree that can be opened so that the opening is shortened.
Therefore, it can be started appropriately according to the air-conditioning place, and it can be used in various air-conditioning places with the same electronic opening valve with the same maximum opening, so the degree of freedom in design becomes high and the design is easy The effect that it can be done can be exhibited.

FIG. 5 is an enlarged view of the indoor unit of the refrigerant natural circulation cooling system according to the second embodiment of the present invention. The differences from the first embodiment are as follows.
That is, instead of the supply air temperature sensor 8 and the return air temperature sensor 9 in the first embodiment, an inlet side pressure sensor 31 for measuring the inlet side pressure in the refrigerant liquid pipe 5 is provided upstream of the electronic expansion valve 7. Further, an outlet side pressure sensor 32 for measuring the outlet side pressure in the refrigerant gas pipe 6 is provided downstream from the use side heat exchanger 2, and the inlet side pressure sensor 31 and the outlet side pressure sensor 32 are connected to the controller 12. Has been.

Further, as shown in the block diagram of the control system of FIG. 6, pressure difference producing means 33 is provided instead of the temperature difference calculating means 16, and the inlet side pressure measured by the inlet side pressure sensor 31 and the outlet side pressure sensor 32. The difference from the outlet side pressure measured at is calculated.
The comparison means 17 compares the pressure difference calculated by the pressure difference calculation means 33 with the set value (0.3P). When the calculated pressure difference is not greater than or equal to the set value, an unstart signal is output, and the calculated pressure difference is When the set value is exceeded, a steady cooling operation transition signal is output.
The comparison means 17 outputs the temperature difference steady cooling operation transition signal calculated by the temperature difference calculation means 16.

  Here, as the set value (0.3P), a steady transition pressure difference that can be determined to be a state capable of transitioning to the steady cooling operation state is set. More specifically, a value of 30% (0.3P) is set for the pressure difference P in the steady cooling operation state. As this setting value, a value of 25 to 50% may be set. This is because the pressure difference after the operation is a result indicating that the refrigerant gas has escaped and the refrigerant liquid has started to flow and be supplied to the use-side heat exchanger 2, and accordingly, natural circulation is smoothly performed. This is because it can be determined that the state is to be performed.

The opening degree control means 18 switches the opening degree of the electronic expansion valve 7 to a necessary opening degree in the steady cooling operation state in response to the steady cooling operation transition signal from the comparison means 17 after the start of the cooling operation. .
In the inoperability determining means 19, the pressure difference calculated by the pressure difference calculating means 33 does not become a steady transition pressure difference that can be determined to be a state capable of shifting to the steady cooling operation state even after a set time has elapsed after the start of the cooling operation. Sometimes it can not start.

  Further, as shown in the flowchart of FIG. 7, instead of each of steps S4 and S8 for determining whether or not activation is possible, it is determined whether or not the pressure difference ΔP is greater than or equal to the set pressure difference. Yes. That is, when the pressure difference ΔP is not equal to or greater than the set pressure difference, that is, when it is determined that the start is impossible, the start disable signal is output and the control shifts to start control. When it is determined that it has been activated, the routine proceeds to steady control. Other configurations are the same as those of the first embodiment, and the description thereof is omitted by assigning the same reference numerals.

  The present invention is not limited to the case where a large number of indoor units 1 are provided on each of a plurality of floors of a building as described above. For example, when a plurality of indoor units 1 are provided on one floor, or a single indoor unit 1 is provided. It can also be applied to cases.

It is a whole lineblock diagram showing the refrigerant natural circulation type cooling system concerning Example 1 of the present invention. It is an enlarged view of an indoor unit. It is a block diagram which shows a control system. It is a flowchart which shows starting control operation | movement. It is an enlarged view of the indoor unit of the refrigerant | coolant natural circulation type cooling system which concerns on Example 2 of this invention. It is a block diagram which shows a control system. It is a flowchart which shows starting control operation | movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Indoor unit 2 ... Use side heat exchanger 4 ... Condenser 5 ... Refrigerant liquid piping 6 ... Refrigerant gas piping 7 ... Electronic expansion valve 8 ... Supply air temperature sensor 9 ... Return air temperature sensor 16 ... Temperature difference calculation means 17 ... Comparison means 18 ... Opening degree control means 19 ... Start-up impossibility determination means 20 ... Support indoor unit selection means 22 ... Abnormality determination means 31 ... Inlet side pressure sensor 32 ... Outlet side pressure sensor 33 ... Pressure difference calculation means

Claims (5)

A plurality of indoor units including use side heat exchangers that evaporate and evaporate a refrigerant that changes phase between gas and liquid and dissipate cold heat are provided, and the use side heat exchanger and a condenser that condenses and liquefies the refrigerant are provided. The refrigerant liquid pipe and the refrigerant gas pipe are connected to each other, the condenser is disposed above the use side heat exchanger, and the natural heat circulates between the condenser and the use side heat exchanger. The refrigerant liquid pipe is provided with a head difference sufficient to transfer the refrigerant liquid condensed and liquefied by the condenser to the use side heat exchanger and to transfer the refrigerant gas evaporated and evaporated by the use side heat exchanger to the condenser. In the refrigerant natural circulation type cooling system provided with an electronic expansion valve for adjusting the amount of refrigerant liquid supplied to the use side heat exchanger,
A supply air temperature sensor for measuring a supply air temperature of the temperature-controlled air blown out from the use side heat exchanger;
A return air temperature sensor for measuring the return air temperature of the temperature-controlled air returned to the use side heat exchanger;
A temperature difference calculating means for calculating a difference between the return air temperature measured by the return air temperature sensor and the supply air temperature measured by the supply air temperature sensor;
Comparing means for outputting a steady cooling operation transition signal when the temperature difference calculated by the temperature difference calculation means becomes a steady transition temperature difference that can be determined to be a state capable of transitioning to the steady cooling operation state;
An opening degree control means for switching the opening degree of the electronic expansion valve to a required opening degree in a steady cooling operation state in response to a steady cooling operation transition signal from the comparison means after starting the cooling operation;
Even if the set time has elapsed after the start of cooling operation, a start impossible signal is output when the temperature difference calculated by the temperature difference calculating means does not become a steady transition temperature difference that can be determined to be a transition to the steady cooling operation state. A non-startable discrimination means to
In response to the start disable signal from the start disable determination means, the indoor unit selected by selecting the indoor unit having a higher priority among the indoor units excluding the indoor unit scheduled to start and the indoor unit in the cooling operation state. A support indoor unit selection means for outputting a start support signal to the unit and opening an electronic expansion valve of the corresponding indoor unit;
A refrigerant natural circulation type cooling system comprising: A plurality of indoor units provided with use side heat exchangers that evaporate and evaporate a refrigerant that changes phase between gas and liquid to dissipate cold heat, and the use side heat exchanger and a condenser that condenses and liquefies the refrigerant are provided. The refrigerant liquid pipe and the refrigerant gas pipe are connected to each other, the condenser is disposed above the use side heat exchanger, and the natural heat circulates between the condenser and the use side heat exchanger. The refrigerant liquid pipe is provided with a head difference sufficient to transfer the refrigerant liquid condensed and liquefied by the condenser to the use side heat exchanger and to transfer the refrigerant gas evaporated and evaporated by the use side heat exchanger to the condenser. In the refrigerant natural circulation type cooling system provided with an electronic expansion valve for adjusting the amount of refrigerant liquid supplied to the use side heat exchanger,
An inlet side pressure sensor for measuring an inlet side pressure in the refrigerant liquid pipe on the upstream side of the electronic expansion valve;
An outlet-side pressure sensor that measures an outlet-side pressure in the refrigerant gas pipe on the downstream side of the use-side heat exchanger;
Pressure difference calculating means for calculating a difference between an inlet side pressure measured by the inlet side pressure sensor and an outlet side pressure measured by the outlet side pressure sensor;
Comparison means for outputting a steady cooling operation transition signal when the pressure difference calculated by the pressure difference calculation means becomes a steady transition pressure difference that can be determined as a state capable of transitioning to the steady cooling operation state;
An opening degree control means for switching the opening degree of the electronic expansion valve to a required opening degree in a steady cooling operation state in response to a steady cooling operation transition signal from the comparison means after starting the cooling operation;
Even if a set time elapses after the start of cooling operation, an unsuccessful start signal is output when the pressure difference calculated by the pressure difference calculation means does not become a steady transition pressure difference that can be determined to be a transition to the steady cooling operation state. A non-startable discrimination means to
In response to the start disable signal from the start disable determination means, the indoor unit selected by selecting a high priority indoor unit among the indoor units excluding the indoor unit scheduled to start and the indoor unit in the cooling operation state. A support indoor unit selection means for outputting a start support signal to the unit and opening an electronic expansion valve of the corresponding indoor unit;
A refrigerant natural circulation type cooling system comprising: In the refrigerant natural circulation type cooling system according to claim 1 or 2,
An abnormality determination that outputs an abnormality signal when the activation disable signal is received from the activation disable determination means even after the activation support signal is output to all of the corresponding indoor units from the support indoor unit selection means and the support operation is completed. Refrigerant natural circulation type cooling system provided with means. In the refrigerant natural circulation type cooling system according to any one of claims 1, 2, and 3,
Indoor units are installed at different heights in the vertical direction,
The refrigerant natural circulation type cooling system in which the support indoor unit selection means is set so that the priority is higher in the indoor unit at the lower position. In the refrigerant natural circulation cooling system according to any one of claims 1, 2, 3, and 4,
An indoor unit is provided in a state where the distance is different in the horizontal direction in the refrigerant liquid pipe in the vertical direction,
The refrigerant natural circulation type cooling system in which the support indoor unit selection means is set so that the priority is higher in an indoor unit located farther from the refrigerant liquid pipe in the vertical direction.

Images