JPH0442665Y2 - - Google Patents

Description

[Detailed explanation of the idea] (Industrial application field) This invention relates to an air conditioner.

(Prior Art) It is known to add an electric heater to an indoor unit in order to supplement the heating capacity of a heat pump type air conditioner, as described in, for example, Japanese Patent Laid-Open No. 57-2946. The main purpose of this is to improve heating speed by using heater heating when a large heating capacity is required, such as during start-up operation. Therefore, the electric heater as described above is controlled to operate when the difference between the set temperature and the room temperature is large, and to stop when the difference between the two temperatures becomes small.

In the device described in the above publication, when the heat pump cycle is operated by the compressor with variable compression capacity and the electric heater is energized at the same time, the total input current to the device exceeds the maximum allowable current. If the current exceeds the maximum allowable current, the compressor is switched to low compression capacity operation using a heat pump cycle that has higher energy conversion efficiency than heater heating. The priority is to continue driving.

However, when the power supply to the electric heater is stopped as described above, the main purpose of the electric heater, which is rapid heating during start-up operation, cannot be achieved. Therefore, the upper limit setting value of the current that can be input to the compressor with variable compression capacity is changed to a value that is lower than the maximum allowable current value by the amount of current applied to the electric heater when energizing the electric heater. By operating the compressor with a compression capacity within this range, the operation of the heat pump cycle and the supply of electricity to the electric heater can be continued at the same time, and the input current when the heater is energized is The regulation system allows for faster heating and more efficient operation.

(Problem to be solved by the invention) By the way, the heating capacity of the heat pump cycle as described above varies depending on changes in outside temperature. In other words, the higher the outside temperature, the greater the heating capacity. For example, when starting up heating when the outside temperature exceeds 15 degrees Celsius, sufficient rapid heating can be achieved even by operating only the heat pump cycle. . However, conventionally, while the difference between the set temperature and the detected room temperature is large, the electric heater is energized in response to a request from the indoor side, and at this time, the heat pump cycle is As a result, even though more efficient operation is possible without sacrificing indoor comfort, the problem is that the energy conversion efficiency is low. .

In recent years, multi-type air conditioners have also been put into practical use, in which a plurality of indoor units are connected to one outdoor unit. In such a device, even if heating operation at low outside temperatures requires supplementary heating by energizing the electric heater when other rooms are operated simultaneously, for example, when heating only one room, it is possible to operate other rooms simultaneously. Since the heating capacity that can achieve this is concentrated in one room, a sufficiently large heating performance is provided. However, conventionally, even in such a case, there has been a problem in that the heater is operated at the same time as electricity is supplied to the low-efficiency heater based on the temperature difference between the set temperature and the room temperature.

This idea was made in view of the above,
The purpose is to provide an air conditioner that can suppress unnecessary electrical heating of the electric heater and thereby improve heating operation efficiency.

(Means for Solving the Problems) Therefore, the air conditioner of this invention includes an outdoor unit X having a variable compression capacity compressor 1 and an outdoor heat exchanger 2, and a plurality of The indoor units A and B are connected in parallel to each other to form a refrigerant circulation circuit, and each of the indoor units A and B is provided with an electric heater 7, and the electric heater 7 is operated based on a request on the indoor side. As shown in FIG. 1, the air conditioner is equipped with a heater operation control means 63 for controlling the temperature of the outside air.
, a load capacity grasping means 61 for grasping the total indoor load capacity, a storage means 70 for storing the stop temperature for stopping the operation of the electric heater 7 as a different value for each load capacity, and the detected outside air. Heater stop control means 71 is provided for outputting a heater stop command to the heater operation control means 63 when the temperature exceeds the above-mentioned stop temperature corresponding to the total load capacity at that time.

(Function) As described above, when the outside temperature is high, rapid heating can be achieved without energizing the electric heater 7 during heating start-up operation, and in a multi-type air conditioner, When the total load capacity on the indoor side is small, for example, when the number of indoor units A and B in operation is small, the above-mentioned rapid heating performance can be obtained using only the heat pump cycle even at lower outside air temperatures. Therefore, in the air conditioner having the above configuration, the outside air temperature (stop temperature) that makes it unnecessary to energize the electric heater 7 as described above is stored in advance in the storage means 70 for each load capacity, and is detected. If the outside air temperature exceeds the above-mentioned stop temperature that corresponds to the total load capacity of the indoor side being operated at that time, even if there is a request from the indoor side to operate the heater based on, for example, the temperature difference between the set temperature and the room temperature. , the electric heater 7 is not energized, and heating operation using only the heat pump cycle is performed. In this way, it is automatically determined that the heating capacity of the heat pump cycle is sufficient for the total indoor load capacity, and the power supply to the electric heater 7 is controlled based on the result. Quick heating during heating is ensured, and unnecessary energization of the electric heater is suppressed, resulting in improved heating operation efficiency.

(Example) Next, a specific example of the air conditioner of this invention will be described in detail with reference to the drawings.

FIG. 2 shows a refrigerant circuit diagram of an air conditioner according to an embodiment of this invention. In the diagram
indicates an outdoor unit, and A and B indicate indoor units, respectively. Outdoor unit X is composed of a compressor 1, an outdoor heat exchanger 2, an outdoor fan 3, a pressure reducing mechanism 4, etc. B includes an indoor heat exchanger 5, an indoor fan 6, an electric heater 7 that serves as an auxiliary heat source during heating operation, and the like. The compressor 1 is equipped with a drive source 9 using an inverter, and its discharge pipe 10 and a suction pipe 11 in which an accumulator 13 is interposed are connected to a four-way switching valve 12. A first gas pipe 14 is connected to one connection port of the four-way switching valve 12, and a second gas pipe 15, an outdoor heat exchanger 2, and a liquid pipe 16 are connected to the other connection port in this order. From the first gas pipe 14, a pair of first gas branch pipes 17,
18, and a pair of liquid branch pipes 1 from the liquid pipe 16.
9 and 20 are branched, and each indoor heat exchanger 5 is connected between them. The above pressure reducing mechanism 4
A series circuit including first capillary tubes 21, 22 and first on-off valves 23, 24 is interposed in each liquid branch pipe 19, 20, and a non-return circuit is provided in liquid pipe 16 with a second capillary tube 25. Valve 26 and second on-off valve 27
It is constructed by interposing a parallel circuit with. Note that the check valve 26 is arranged to allow the flow of refrigerant only during cooling. In the same figure, 30 and 31 are mufflers, 32 is a gas shutoff valve,
33 represents a liquid shutoff valve, and 34 represents a dryer filter. The liquid pipe 16 between the outdoor heat exchanger 2 and the dryer filter 34 is discharged by a positive cycle defrost bypass pipe 35 which has a defrost on-off valve 36 and a throttle 37 formed of a capillary tube. It is connected to piping 10. Note that the bypass pipe 35 and the discharge pipe 1
0, check valves 38 and 39 are provided near the branch points, respectively. Further, in the vicinity of the outdoor heat exchanger 2, an outside air temperature detection sensor (outside air temperature detection means) 4 consisting of a thermistor for detecting the outside air temperature is provided on the circulation path of the atmosphere passing through the outdoor heat exchanger 2.
0 is set.

In the above air conditioner, the four-way selector valve 12 is installed so that the refrigerant circulates in the direction (in the direction of the broken line arrow in the figure) in which the outdoor heat exchanger 2 functions as a condenser and each indoor heat exchanger 5 functions as an evaporator. Switch to compressor 1
Cooling operation is performed by driving the . At this time, the second on-off valve 27 and the defrost on-off valve 3
6 are both closed, and each first on-off valve 23, 2 is closed.
4 closes the stop side and opens the drive side. On the other hand, in heating operation, the four-way switching valve 12 is switched from the above, and the refrigerant is circulated in the direction (in the direction of the solid line arrow in the figure) in which each indoor heat exchanger 5 functions as a condenser and the outdoor heat exchanger 2 functions as an evaporator. This is done by causing At this time, the defrost on-off valve 36 is closed, and the first on-off valves 23 and 24 are both opened. When the two chambers are operated simultaneously, the second on-off valve 27 is closed. Also, when operating in one room alone, the indoor fan on the stopped side is stopped.
In this case, the refrigerant flowing through the indoor heat exchanger on the stopped side is not given any heat exchange beyond natural heat radiation, resulting in a gas-liquid mixed state with a large gas component. The first capillary tube 22 acts as a large flow resistance, and therefore the amount of refrigerant flowing through the indoor heat exchanger on the stopped side is limited to a small amount, and most of the refrigerant is circulated through the indoor heat exchanger on the operating side. However, by keeping the stopped side in a state where it can flow as described above, it is possible to prevent liquid from accumulating. During this single room operation, the second on-off valve 27 is opened when the operating frequency of the compressor 1 is higher than a preset reference frequency (for example, about 45 Hz), and when the operating frequency is lower than the reference frequency. Close if . This is because when the operating capacity of the compressor 1 is low, the amount of refrigerant flowing through the first capillary tube 21 on the operating side is small and sufficient pressure reduction characteristics cannot be obtained, so the second capillary tube 25 further reduces the pressure. This is to maintain an appropriate decompression effect.

When the above heating operation is performed at low outside temperatures, for example, the user may turn off the heater operation switch if he or she determines that quick heating is not possible when starting the heating.
On the premise of the ON operation, the electric heater 7 described above is energized as appropriate depending on the operating situation. Next, the drive frequency control of the compressor 1 during the heating operation and the heater energization control as described above will be explained based on the control block diagram of FIG. 3.

As shown in the figure, this air conditioner has indoor control devices 51 arranged in each indoor unit A and B, respectively.
and the outdoor control device 5 arranged in the outdoor unit
2, and each indoor control device 51 has:
An operation switch 53, a temperature setting unit 54 for setting the desired air conditioning temperature, a room temperature sensor 55 for detecting room temperature, and a heater operation switch 56 operated when the user desires heater heating by the electric heater 7. They each have the following. The operation switch 53 is connected to each indoor control device 51.
On the premise that the temperature detected by the room temperature sensor 55 has not reached the set temperature, an operation request signal is generated together with the temperature difference signal, and the heater operation switch 56 is ON and the temperature When the difference is a set value, for example 2°C or more, the heater ON request signal is activated by the outdoor control device 52.
is output to.

On the other hand, the outdoor control device 52 includes a load capacity grasping means for grasping the total load capacity on the indoor side, that is, an operation number grasping section 61, a frequency control section 62, and a heater operation control section (heater operation control means) 63. have. The operation request signal from the indoor side is input to the operating unit number determining section 61, and the operating unit number determining section 61 determines the number of indoor units A and B whose operation is requested. Based on this required number of units to be operated and the temperature difference signal from the indoor side, the frequency control unit 62 determines the capacity of the compressor 1, that is, the inverter frequency, and drives the compressor 1 at this frequency. There is. The inverter frequency at this time is determined as follows. In other words, the frequency control section 62 stores in advance the initial setting frequency corresponding to the number of operating units and the temperature difference as a data table, and operates at startup or when the indoor thermostat is turned on, that is, when the room temperature reaches the set temperature. When restarting operation when a temperature difference occurs again after stopping the system, the system starts operation at the initial setting frequency according to the number of units requested for operation at that time and the temperature difference,
After reaching the set frequency, frequency control is performed in accordance with changes in indoor air conditioning load, for example, by PID control or the like, based on subsequent detected temperature differences. Therefore, for example, during the start-up period immediately after the start of heating operation when there is a large temperature difference between the set temperature and the room temperature, the operating frequency of the compressor 1, which was started at the initial setting frequency, will be changed for a short period of time due to the large temperature difference. It rises to its maximum frequency,
As the operation continues, the temperature difference becomes smaller, and control is performed to shift to the lower frequency side again. Note that the input current to the inverter 9 at this time is determined by the current detection sensor 6.
5, and the detection signal is compared with a predetermined first allowable current value in a current comparison section 66. In the process of increasing the drive frequency of the compressor 1 as described above, if the input current to the inverter 9 exceeds the first allowable current value, a drooping current is applied from the current comparison section 66 to the frequency control section 62. A command is input, and at this time, the frequency control section 62 interrupts the PID control according to the temperature difference signal from the indoor side, and performs control to maintain the current drive frequency or decrease it at a constant rate. conduct. Thereby, control is performed to maintain the input current to the inverter 9 at the first allowable current value.

On the other hand, the heater ON request signal from the indoor side is input to the heater operation control section 63. While this request signal is being input, the heater operation control section 63 receives a maximum capacity operation state signal from the frequency control section 62, a surplus state signal from the current comparison section 66, and a heater stop control section 71, which will be described later. The stop release signal is determined from the stop release signal. The maximum capacity operation state signal is generated when the frequency increases as a result of the PID control based on the temperature difference signal from the indoor side and the operation is performed at the maximum frequency, or when the compression is performed while maintaining the first allowable current value. This is generated by the frequency control unit 62 when the compression capacity is restricted from increasing any further, such as when the machine 1 is operating. When such a maximum capacity operating state signal is generated, the heater operation control section 63 sends the current comparator 66 an allowable current value for comparing the input current to the inverter 9 with the first allowable current. A change command is output to change the value to a second allowable current value smaller than the second allowable current value. In other words, the above-mentioned second allowable current value is such that when the input current to the inverter 9 is less than this, the total input current to this device does not exceed the allowable value even when the electric heater 7 is energized. On the other hand, the first allowable current value is set as a value that allows the maximum input to the inverter 9 when only the heat pump cycle is operated. Therefore, when the electric heater 7 is energized, the upper limit of the compression capacity of the compressor 1 is lowered by the amount of current applied to the electric heater 7.

The surplus state signal from the current comparator 66 is generated when the input current to the inverter 9 is equal to or less than the second allowable current value. The current comparison section 66
When the change command described above is input, if the input current to the inverter 9 exceeds the second allowable current value, a droop command is output from the current comparison section 66 to the frequency control section 62, and thereby The frequency control section 62 performs control to reduce the frequency at a constant rate, and as a result, when the input current to the inverter 9 decreases to the second allowable current value, the current comparison section 66 controls the heater operation control section. A surplus status signal is output to 63.

When each of the above signals is input to the heater operation control section 63, a heater ON command is output from the heater operation control section 63 to the indoor unit that is outputting the heater ON request signal, and this causes the electric heater to turn on. 7 starts to be energized. Then, when the temperature difference between the indoor side becomes small, for example, 2°C or less, the heater ON request signal from the indoor side is canceled, and the electricity to the electric heater 7 is stopped, and only the heat pump cycle is started. He will return to driving. Further, in the above device, in order to suppress unnecessary energization operations to the electric heater 7, the heater stop control section (heater stop control means) 71 including a storage section (memory means) 70 is provided, and the heater stop control section (heater stop control means) 71 is provided, and The control section 63 performs the above-described energization control after also determining the presence or absence of the stop release signal generated by the heater stop control section 71. Therefore, next, the heater stop control section 71
The method of generating the stop release signal performed in the step will be explained based on the flowchart of FIG.

When the operation of the apparatus is started, the heater stop control section 71 first initializes flag bits F15 and F5 to 0, as shown in step S1 in FIG. These flag bits are used to remember that the outside air temperature has exceeded a stop temperature, which will be described later. Next, in step S2, it is determined based on the output from the operating unit number grasping section 61 described above whether there is an operation request for both indoor units A and B, or whether there is an operation request for only one indoor unit.
In the case of YES, that is, in the case of two-room simultaneous operation state, the process moves to step S3, and the outside air temperature Tg detected by the above-mentioned outside air temperature detection sensor 40 is used as the two-room simultaneous operation state stored in advance in the storage section 70. Compare with the stop temperature of 150°C, for example 15°C. and above
If Tg is 15° C. or higher, the flag bit F15 is set to 1 in step S4, and a heater stop signal is output to the heater operation control section 63 in step S5. Next, the process returns to step S2 above, but as long as the two-room simultaneous operation state and the temperature state where Tg is 15°C or higher continue, steps S2 to S5 are repeated, and therefore the output of the heater stop signal is continue. While this heater stop signal is being output, the heater operation control section 63 controls the heater operation from the indoor side.
Even when the ON request signal is input, the power supply to the electric heater 7 is stopped without determining the maximum capacity operating state signal from the frequency control unit 62 or issuing a change command to the current comparison unit 66. The state is maintained and only the heat pump cycle continues to operate.

On the other hand, while the above operation continues, the outside air temperature Tg
If the temperature drops below 15℃, proceed to step S3 above.
Then, the process moves to S6, and since the flag bit F15 is 1, the Tg is compared with the return temperature at the time of simultaneous operation of two rooms stored in the storage section 70, for example, 13° C. in step S7. If the temperature exceeds 13 DEG C., that is, if the temperature is between 13 DEG C. and 15 DEG C., the process moves from step S7 to step S5, and the output of the heater stop signal continues. Then, when the Tg further decreases to 13°C or less, steps S7 to S8 are performed.
In this step, the flag bit F15 is reset to 0, and the step
In S9, a heater stop release signal is output to the heater operation control section 63. Assuming that this heater stop release signal is output,
The heater operation control section 63 controls the supply of electricity to the electric heater 7 described above. In other words, in the simultaneous operation of two rooms, if the outside air temperature Tg is 15°C or higher, and even if it is below 15°C, the electric heater will not be turned on until the temperature drops to 13°C or lower after it reaches 15°C or higher. The power supply to 7 is forcibly stopped regardless of the presence or absence of a heater ON request signal from the indoor side. Note that if the temperature is less than 15° C. from the beginning, the initial setting value of F15=0 is continued, so the process moves from step S6 to S9, and a heater stop release signal is output.

On the other hand, if the operation request from the indoor side is for only one of indoor units A and B, the process moves from step S2 to S10, and the stop temperature at the time of single room operation stored in advance in the storage section 70 is (For example, 5
By comparing the outside air temperature Tg with the return temperature (for example, 3° C.) in the same manner as above, a heater stop signal or a heater stop release signal is output. In other words, when the above Tg becomes 5°C or more (steps S10, S11, S5), and once it becomes 5°C or more until it falls to 3°C (steps S10, S11, S5),
Steps S10, S12, S13, S5) output a heater stop signal, and on the other hand, if the temperature drops to 3°C or less after once reaching 5°C or higher (steps S10, S12, S13, S14,
S9), and if the temperature is below 5℃ from the beginning (step
S10, S12, S9) output a heater stop release signal.

As described above, the heater stop control unit 71 controls the heating operation from the indoor side during simultaneous heating operation of two rooms when the outside air temperature is 15°C or higher, and during single room heating operation when the outside air temperature is 5°C or higher. Even when there is a heater ON request signal, the heater is forcibly stopped and only heating operation using the heat pump cycle is performed. In other words, the heating capacity of the heat pump cycle increases as the outside air temperature increases. Therefore, in operation at high outside temperatures exceeding 15 degrees Celsius, for example, when heating is started, the electric heater 7 must not be energized. In both cases, a sufficiently satisfactory heating speed can be obtained. However, in the past,
When there is a request to operate the heater from the indoor side, even in the above cases, the heater is uniformly operated in combination with energization, which has low energy conversion efficiency, resulting in an uneconomical operating state. In the embodiment described above, unnecessary energization of the heater as described above is suppressed when the outside temperature is high, and as a result, heating operation efficiency can be improved without impairing indoor comfort. In addition, multi-type air conditioners are selected to have a heating capacity that can provide approximately comfort to each room operated simultaneously under the rated operating condition (outside temperature 7°C). Therefore, even if the outside air temperature is lower than the above, when operating a smaller number of rooms with this device, for example, only one room, the heating capacity that was distributed during multi-room operation will be concentrated in only one room. Therefore, great heating performance can be obtained in this operating room. Therefore, in this case as well, by forcibly stopping the heater energization in the same manner as described above, unnecessary combined operation of heater energization is suppressed, and heating operation efficiency is improved.

As explained above, in the above embodiment, the operating condition that can provide quick heating when starting up heating, for example, is automatically determined from the outside air temperature and the number of operating rooms without using heater power, and In some cases, the heater is forcibly de-energized, so that low-efficiency heater heating operation is suppressed without impairing indoor comfort, thereby making it possible to improve heating operation efficiency. The above also applies to the steady heating operation, the room temperature recovery operation by turning on the indoor thermostat described above, and the like. Conventionally, there were cases where the heater was frequently energized for a short time every time the indoor thermostat was turned on, but in the above embodiment, such intermittent heater energization is also suitable based on the outside temperature and the number of rooms in operation. As a result, the lifespan of electric components such as the electric heater 7 and its drive relay is improved, and the number of times the contact opening/closing operation noise is generated in the drive relay is reduced.

In the above embodiment, the load capacity on the indoor side is determined by the number of operating indoor units A and B, but if there is a large difference in the rated capacity of the indoor units placed in each room, for example, In such a case, it is also possible to output a signal corresponding to the rated capacity value from each indoor unit together with the operation request signal, and configure such a rated capacity value to be grasped as the load capacity. Further, although the above description is for an air conditioner equipped with two indoor units A and B, this invention can also be applied to a multi-type air conditioner having three or more indoor units.

(Effect of the invention) As mentioned above, in the air conditioner of this invention, based on the indoor load capacity and the outside temperature,
Even if the heat pump cycle is used alone, the operating state that does not impair indoor air conditioning comfort is suitably determined, and at this time, control is performed to maintain the power supply to the electric heater in a forced stop state, thereby improving energy conversion efficiency. Combined operation of low heater current heating is suppressed, and as a result, heating operation efficiency is improved.

[Brief explanation of drawings]

Fig. 1 is a functional block diagram of this invention, Fig. 2 is a refrigerant circuit diagram of an air conditioner according to an embodiment of this invention, Fig. 3 is a control block diagram of the above device, and Fig. 4
The figure is a flowchart showing a decision method for stopping and canceling the heater in the heater stop control section. X... Outdoor unit, A, B... Indoor unit, 1... Compressor, 2... Outdoor heat exchanger, 5...
Indoor heat exchanger, 7... electric heater, 40... outside air temperature detection sensor (outside air temperature detection means), 61...
Operating unit number grasping unit (load capacity grasping means), 63...
Heater operation control section (heater operation control means), 70
. . . Storage section (storage means), 73 . . . Heater stop control section (heater stop control means).

Claims (1)

[Scope of utility model registration request] A plurality of indoor units A and B each having an indoor heat exchanger 5 are connected in parallel to an outdoor unit X having a compressor 1 with variable compression capacity and an outdoor heat exchanger 2 to form a refrigerant circulation circuit. , each of the indoor units A and B is provided with an electric heater 7, and a heater operation control means 6 for controlling the operation of the electric heater 7 based on a request on the indoor side.
3, the air conditioner further includes an outside temperature detection means 40 for detecting the outside air temperature, and a load capacity grasping means 6 for grasping the total load capacity on the indoor side.
1, a storage means 70 for storing a stop temperature for stopping the operation of the electric heater 7 as a different value for each load capacity, and a storage means 70 for storing the stop temperature for stopping the operation of the electric heater 7 as a different value for each load capacity; When the temperature exceeds the limit, the heater operation control means 63 issues a heater stop command.
An air conditioner characterized in that it is provided with a heater stop control means 71 that outputs an output to the air conditioner.