JP3147707B2 - Heat pump multi-system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump multi-system for performing a defrosting operation by switching the refrigerant circulation to a reverse cycle.

[0002]

2. Description of the Related Art In a separate type air conditioner, for example, if frost forms on an outdoor heat exchanger during a heating operation, the heating capacity is reduced due to the formation of frost. It may be necessary to switch to frost operation. In a conventional air conditioner, in order to perform this switching automatically, the heat exchange efficiency with the outside air is reduced due to frosting, whereby the evaporation temperature of the outdoor heat exchanger is reduced, and the temperature of the outdoor heat exchanger itself is reduced. Utilizing the phenomenon that the temperature decreases,
When the temperature of the outdoor heat exchanger becomes equal to or lower than the defrost start temperature, the refrigerant circuit is switched to the reverse cycle to start the defrost operation.

However, a multi-type heat pump system in which a plurality of indoor heat exchangers, a heat exchanger for bath heating and a heat exchanger for hot water supply heating can be connected in parallel to one outdoor heat exchanger. In this case, in the above-described defrosting operation, even when the amount of frost on the outdoor heat exchanger at the start of defrosting is substantially the same, the time required for the defrosting is determined by the above-mentioned utilization immediately before the start of defrosting. It is also greatly affected by the operation status of each heat exchanger on the side. That is, in the defrosting operation operation in which the refrigerant circuit is switched to the reverse cycle, the use side heat exchanger acts as an evaporator similarly to the cooling cycle, and the amount of heat absorbed by the circulating refrigerant from around the use side heat exchanger. This is because heat is radiated by the outdoor heat exchanger to remove defrost. Therefore, the greater the amount of heat that can be absorbed by the use side heat exchanger, the greater the defrosting capacity, and the shorter the defrosting time is. The defrosting ability increases as the number of operating side heat exchangers increases. Therefore, unlike a device in which the number of use side heat exchangers is one and the defrosting ability is substantially constant, a multi-type In the heat pump system described above, the time required to complete the defrost varies depending on the number of the use-side heat exchangers in the heating operation state immediately before the start of the defrost. For this reason, the multi-type heat pump system has a problem that the proper defrosting operation condition cannot be obtained depending on the method of keeping the defrosting time constant, and thus the heating capacity cannot be improved.

In order to solve this problem, there is a heat pump multi-system described in Japanese Patent Application Laid-Open No. 63-32269. FIG. 5 is a functional block diagram showing the defrosting operation control in the above system. As shown in FIG.
A load capacity grasping means 39 for grasping the total load capacity value of No. 5 is provided. In addition, the time storage means 40 stores a reference defrost time corresponding to the total load capacity value in advance, and the reference defrost time setting means 41 uses the total load capacity value input from the load capacity grasping means 39, The reference defrost time corresponding to this is read from the time storage means 40 and is output to the defrost start temperature changing means 42. The defrosting start temperature changing means 42 compares the time actually required for defrosting with the input reference defrosting time. If the reference defrosting time is longer than the defrosting operation time, the defrosting start temperature changing means 42 starts defrosting. The temperature is increased, and if the defrosting operation time is longer than the reference defrosting time, the defrosting start temperature is decreased. On the other hand, the temperature detecting means 44 detects the temperature of the heat source side heat exchanger, compares the detected temperature with the defrost start temperature and the end temperature, and the defrost operation control means 43 controls the defrost operation.

[0005] With the above configuration, in the above system, the defrosting start temperature is corrected and changed so that the proper defrosting operation is performed even when the operating condition of the use side heat exchanger 45 is different. In addition, unnecessary defrosting operation can be suppressed, and the heating operation time can be extended to improve heating efficiency.

[0006]

In the above-described heat pump multi-system, the defrosting start temperature is changed according to the operation state of the use side heat exchanger 45, thereby trying to obtain an appropriate defrosting operation. Therefore, when the number of connected use-side heat exchangers 45 is small and the total load capacity value is small, the defrosting start temperature is set higher, and the defrosting operation can be easily started with a small amount of frost. . However, since the temperature detecting means 44 usually composed of a temperature detecting sensor such as a thermistor has a limit of accuracy, the temperature of the heat source side heat exchanger and the defrost start temperature at the time of the heating operation are close to each other as described above. In such a case, it is difficult to reliably obtain the intended effect of improving the heating efficiency, such as starting the defrosting operation by the defrosting operation control unit 43 making an erroneous determination. was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and has as its object to secure a predetermined heating efficiency even when the load capacity on the user side is small, and to surely improve the user comfort. It is an object of the present invention to provide a heat pump multi-system that can be operated.

[0008]

Therefore, a heat pump multi-system according to claim 1 enables a plurality of use side heat exchangers 9 to be connected to one heat source side heat exchanger 1 as shown in FIG. While the heating operation is performed by circulating the refrigerant from the use side heat exchanger 9 to the heat source side heat exchanger 1, temperature detecting means 18 for detecting the temperature of the heat source side heat exchanger 1, When the detected temperature Td becomes equal to or lower than the defrost start temperature Ts, the refrigerant is circulated from the heat source side heat exchanger 1 to the use side heat exchanger 9 to start a reverse cycle defrosting operation. Defrosting operation control means 3 for stopping the defrosting operation when the detected temperature Td exceeds the defrosting end temperature Te
1. The heat pump multi-system according to claim 1, further comprising: a defrost forcible stop means 32 for forcibly stopping the defrosting operation when the operation time td of the defrosting operation exceeds the reference defrosting time te. After the defrost operation is stopped by the forced frost stop means 32, a defrost operation prohibiting means 34 for prohibiting the defrost operation from being restarted until the reference heating time tq has elapsed is provided . By means 32
When the frost operation is stopped, the defrost start temperature Ts is
Change to a temperature higher than the temperature at which the frost operation was started
A frost start temperature changing means 33 is provided .

[0009]

Further, in the heat pump multi-system according to the second aspect , a plurality of use side heat exchangers are connected to one heat source side heat exchanger 1.
Exchanger 9 can be connected, and the heat source side from the use side heat exchanger 9
While performing the heating operation by circulating the refrigerant to the heat exchanger 1,
Temperature detecting means 18 for detecting the temperature of the heat source side heat exchanger 1
And the temperature Td detected by the temperature detecting means 18 starts defrosting.
When the temperature becomes equal to or lower than Ts, the heat source side heat exchanger 1 switches to the use side.
The refrigerant is circulated to the heat exchanger 9 to perform the reverse cycle defrosting operation.
Start, and then the temperature Td detected by the temperature detecting means 18
Stops the defrosting operation when the temperature exceeds the defrost end temperature Te
Heat pump multi-equipped with a defrosting operation control means 31
In the system, the operation time td of the defrosting operation is the standard defrosting.
Defrosting forcibly stopping the defrosting operation when time te is exceeded
A forced stop means 32 is provided.
32, the reference heating time t after the defrosting operation is stopped
Prohibit restart of defrosting operation until q elapses
Defrosting operation inhibiting means 34 and the defrosting operation inhibiting means 3
The defrosting forced start means 35 for forcibly starting the defrosting operation after the elapse of the reference heating time tq in which the restart of the defrosting operation is prohibited by No. 4 is provided.

[0011]

In the heat pump multi-system according to the first aspect, after the defrost operation is forcibly stopped by the defrost forcible stop means 32, the reference heating time tq is secured by the defrost operation prohibiting means 34, and the defrost operation is performed during this time. Is banned. Therefore, it is possible to secure a predetermined heating operation rate and to surely improve the driving comfort on the user side. Also, defrost forced stop hand
After the defrosting operation is forcibly stopped by the stage 32,
If the defrost operation is started, a higher defrost start temperature
It starts at Ts. Therefore, the residual melting in the previous defrosting operation
Can be reliably removed.

[0012]

Further, in the heat pump multi-system according to the second aspect , the defrost operation is forcibly stopped by the defrost forced stop means 32.
After stopping, the reference heating time
tq is secured, and the defrosting operation during this period is prohibited. Obedience
To ensure a certain heating operation rate and ensure reliable operation on the user side.
It is possible to improve comfort. Moreover, after the reference heating time tq has elapsed from the stop of the forced defrosting operation has been started forcibly defrosting operation again. Therefore ,
It becomes possible to secure the use comfort while performing actual defrosting .

[0014]

Next, a specific embodiment in which the heat pump multi-system of the present invention is configured as an air conditioner will be described.
This will be described in detail with reference to the drawings.

FIG. 2 shows a plurality of indoor units 11.
1 shows a refrigerant piping system of a multi-type air conditioner provided with: In the figure, reference numeral 10 denotes an outdoor unit,
Is an outdoor heat exchanger serving as a heat source side heat exchanger, 2 is a liquid pipe having one end connected to the outdoor heat exchanger 1, and 3 is a liquid pipe connecting the outdoor heat exchanger 1 and the four-way switching valve 4. The four-way switching valve 4 is connected to a discharge pipe 6 and a suction pipe 7 of a compressor 5 whose capacity is controlled by an inverter 14. One end of a second gas pipe 8 is connected to the four-way switching valve 4, and serves as a use side heat exchanger between the other end of the second gas pipe 8 and the other end of the liquid pipe 2. The indoor heat exchangers 9 are connected in parallel. The outdoor heat exchanger 1 is provided with a thermistor 18 functioning as a temperature detecting means and a blower fan 16, while the indoor heat exchanger 9 is provided with an indoor fan 17. In the figure, reference numeral 12 denotes a first
A motor-operated valve 13 is a second motor-operated valve provided corresponding to each indoor heat exchanger 9, and 15 is an accumulator provided in the suction pipe 7.

In the air conditioner having the refrigerant piping system as described above, the outdoor heat exchanger is operated by switching the four-way switching valve 4 as shown by a broken line and circulating the refrigerant as shown by a broken line arrow in the heating operation. In step 1, the heat absorbed by the outside air as a heat source is released from the indoor heat exchanger 9 to the room. On the other hand, during the cooling operation, the four-way switching valve 4 is switched as shown by the solid line, and the refrigerant is circulated as shown by the solid line arrow in the drawing, so that the transfer of heat quantity is reversed from that during the heating operation. In such a multi-system, when the number of the indoor units 11 to be operated changes, the air-conditioning load greatly changes.
And air-conditioning operation according to the load fluctuation. By the way, in this air conditioner, if frost forms on the outdoor heat exchanger 1 during the heating operation, a defrost operation is performed to remove the frost. When starting this defrosting operation, the thermistor 18 provided in the pipe of the outdoor heat exchanger 1
When the temperature measured by the thermistor 18 becomes equal to or lower than the predetermined defrosting start temperature Ts, it is determined that the amount of frost that requires defrosting has been reached, and the defrosting operation is started. That is, the four-way switching valve 4 is switched as shown by the solid line while the blower fan 16 and the indoor fans 17 are stopped, and the reverse cycle defrosting operation is performed in which the refrigerant is circulated as shown by the solid line arrow in the figure. When the frost adhering to the outdoor heat exchanger 1 is removed, the temperature detected by the thermistor 18 rises. When the temperature exceeds a predetermined defrost end temperature Te, the defrosting operation is terminated and heating is performed. Driving is resumed.

FIG. 3 shows an operation control system of the air conditioner. In FIG. 1, reference numeral 21 denotes a microcomputer having an input / output interface 23, a memory 24, a timer 25, and a CPU 22 for controlling these. The input / output interface 23 receives the outdoor heat exchanger temperature Td from the thermistor 18 and outputs a start / stop signal to the indoor fan 17 and the blower fan 16 and a switching signal to the four-way switching valve 4. The timer 25 measures the time, and the result can be read by the CPU 22. Further, the memory 24 has a defrost start temperature Ts and a defrost end temperature T
e, a reference defrosting time te, a reference heating time tq, a defrosting operation time td, a defrosting inhibition time tp, and a control program for defining the operation of the CPU 22 are stored. In the figure, other control systems, that is, those related to the control of the inverter 14, the electric valves 12, 13 and the like are omitted to avoid complicating the figure and to facilitate understanding. The microcomputer 21 has the following functions. The first function is to control the indoor fan 17, the blower fan 16, and the four-way switching valve 4 according to the input temperature from the thermistor 18 to start and stop the defrosting operation (corresponding to the defrosting operation control means 31). The second is a function for forcibly stopping the defrosting operation in accordance with the result of counting by the timer 25 (corresponding to the defrost forcible stopping means 32), and the third is a defrosting start temperature stored in the memory 24 in a predetermined case. Fourth, a function of changing Ts (corresponding to the defrost start temperature changing means 33), and a fourth function of prohibiting the defrosting operation according to the result of the timer 25 regardless of the input from the thermistor 18 for a predetermined time (defrosting operation) (Corresponding to the frost operation inhibiting means 34).

Next, the operation of the air conditioner will be described with reference to FIG.
However, since it is necessary to explain the control of the defrosting operation, it is assumed that the air conditioner is used for heating. First, when the power is turned on to start the operation of the air conditioner, the defrost end temperature Te, the reference defrost time te, and the reference heating time tq are initialized in step S1. Then, after initial setting of the defrosting start temperature Ts in Step S2, Step S3
Clears the defrosting operation time td and the defrost inhibition time tp,
In step S4, the heating operation is started. Next, step S5
Then, the outdoor heat exchanger temperature Td is read in step S6, and this Td is compared with the above Ts in step S6. If Td is not lower than Ts, the process returns to step S4 to continue the heating operation. The process proceeds to step S7 to start the defrosting operation. In the flowchart of FIG. 4, Td is equal to Ts.
Although the defrosting operation is started even when is equal to, the process may return to step S4 to continue the heating operation when Td is equal to Ts. That is, claim 1
"Below the defrost start temperature Ts" includes both of the above cases.

If the defrosting operation is started in step S7, then, in step S8, t
Start counting d. If the value of td is not larger than te, that is, if the reference defrost time has not yet elapsed since the start of the defrosting operation, step S10 is performed.
Then, Td is compared with Te. Here, when Td exceeds Te, the process returns to step S2 to perform the initial setting of Ts and then starts the heating operation, while when Td does not exceed Te, the process returns to step S7 to perform the defrosting operation. continue. If Td is equal to Te, the process returns to step S7 to continue the defrosting operation. In such a case, control may return to step S2. That is, the description “when the detected temperature Td exceeds the defrost end temperature Te” in claim 1 includes both of the above cases.

If it is determined in step S9 that td is greater than te, the process proceeds to step S11, in which the defrosting operation is stopped and the heating operation is started. Then, in step S12, Ts is set to a value higher than the initial value, and counting of tp is started in step S13. When tp is not greater than tq, that is, while the reference heating time has not yet elapsed since the defrosting operation was stopped, the above-described step S1 is performed.
3 and step S14 are repeated. And t
When p exceeds tq, the process returns to step S3 and returns to step S3.
The above operation is repeated again based on the new Ts changed in 12. If td and te are equal in step S9, the process proceeds to step S10.
You may make it go to 11. That is, the description “when the reference defrost time te is exceeded” in claim 1 includes both of the above cases. Similarly, if tp is equal to tq in step S14, step S13
The control is returned to step S3. That is, the description “until the reference heating time tq has elapsed” in claim 1 includes both of the above cases. Further, in FIG.
Although s is changed in step S12, that is, after stopping the defrosting operation, this may be performed between step S9 and step S11, that is, before stopping the defrosting operation. That is, the description “when the defrosting operation is stopped” in claim 2 includes both of the above cases.

According to the above control, step S9
It is determined whether or not the reference defrosting time te has elapsed since the start of the defrosting operation in step S11. If the reference defrosting time te has elapsed, even if the temperature of the outdoor heat exchanger 1 is equal to or lower than the defrost end temperature Te, it is determined in step S11. The frost operation has been forcibly stopped. After that, the heating operation is continued until the reference heating time tq elapses in steps S13 and S14. Therefore, regardless of the amount of frost, a heating operation rate equal to or higher than a predetermined value can always be ensured. At this time, if the ratio of tq and te is set to about 4: 1, a heating operation rate of about 80% can be secured, and excellent control of driving comfort with less decrease in room temperature can be achieved.

In step S12, the defrosting start temperature T
s is changed to a higher temperature. This temperature difference is about 10
If the temperature is set to about ° C., the defrosting operation is started again in step S6, and the frost remaining unmelted can be reliably removed. At this time, since Ts is increased, there is a possibility that the defrosting operation may be started by mistake due to the accuracy limit of the thermistor 18 as in the conventional air conditioner. Since the capacity of the heat exchanger 1 is sufficiently larger than the capacity of one indoor heat exchanger 9, the amount of frost formed on the outdoor heat exchanger 1 when the number of indoor heat exchangers 9 is small is small, and from step S9. It is rare to proceed to step S11. Moreover, even if the malfunction occurs, a predetermined heating operation rate is always ensured, so that heating comfort is not impaired. Further, instead of the above control, the reference heating time tq is changed without changing Ts in step S12.
After the elapse of the period, the process proceeds from step S14 to step S7, where td
May be performed to force the defrost operation to start, that is, control corresponding to the defrost forcing start means 35. In this case, since the defrosting operation is always restarted regardless of Td, there is no possibility that the malfunction will occur.
Therefore, defrosting can be reliably performed while ensuring heating comfort.

Although the specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be implemented with various modifications within the scope of the present invention. For example, in the above-described embodiment, an example in which the air conditioner is configured is shown. However, the present invention may be applied to another heat pump multi-system having a heat exchanger for hot water supply or bath heating as a use side heat exchanger. Further, the flowchart shown in FIG. 4 is an example, and control by another flowchart may be performed as long as equivalent control can be performed.

[0024]

In the heat pump multi-system according to the first aspect, after the defrost operation is forcibly stopped by the defrost forcible stop means, the reference heating time is secured by the defrost operation prohibiting means.
Defrosting operation during this period is prohibited. Therefore, it is possible to secure a predetermined heating operation rate and to surely improve the driving comfort on the user side. Also, the defrost forced stop means
After the defrost operation is forcibly stopped, the defrost operation is
Be started at a higher defrost start temperature.
You. Therefore, it is possible to reliably remove the unmelted residue from the previous defrosting operation.
It becomes possible.

[0025]

Further, in the heat pump multi-system according to the second aspect, the defrost operation is forcibly stopped by the defrost forcible stop means.
After that, secure the reference heating time by defrosting operation prohibition means
The defrosting operation during this period is prohibited. Therefore the given
Ensuring a heating operation rate to ensure reliable driving comfort on the user side
It is possible to aim up. Further, after the reference heating time elapses after the defrost operation is forcibly stopped, the defrost operation is forcibly started again. Therefore , perform defrosting reliably
It is possible to secure the comfort while using .

[Brief description of the drawings]

FIG. 1 is a functional block diagram of defrosting operation control of a heat pump multi-system according to the present invention.

FIG. 2 is a refrigerant piping system diagram of an air conditioner to which the present invention is applied.

FIG. 3 is an operation control system diagram of the air conditioner.

FIG. 4 is a control flowchart of the air conditioner.

FIG. 5 is a functional block diagram of defrosting operation control according to a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 outdoor heat exchanger 9 indoor heat exchanger 18 thermistor 31 defrosting operation control means 32 defrosting forced stop means 33 defrosting start temperature changing means 34 defrosting operation prohibiting means 35 defrosting forced start means Ts defrosting start temperature Te removal Defrost end temperature Td Outdoor heat exchanger temperature td Defrost operation time te Reference defrost time tq Reference heating time

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-32269 (JP, A) JP-A-59-200144 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 47/02

Claims (2)

(57) [Claims] 1. A plurality of use side heat exchangers (9) can be connected to one heat source side heat exchanger (1), and the use side heat exchanger (9) is connected to the heat source side heat exchanger (1). A temperature detecting means (18) for detecting the temperature of the heat source side heat exchanger (1) while circulating the refrigerant to the heat source (1), and a temperature detecting means (1).
8) When the detected temperature (Td) becomes equal to or lower than the defrost start temperature (Ts), the refrigerant is circulated from the heat source side heat exchanger (1) to the use side heat exchanger (9) to perform reverse cycle defrosting. The operation is started, and thereafter, the temperature detected by the temperature detecting means (18) (T
A heat pump multi-system including a defrosting operation control means (31) for stopping the defrosting operation when d) exceeds the defrosting end temperature (Te), and the operation time (td) of the defrosting operation is A defrost forced stop means (32) for forcibly stopping the defrost operation when the reference defrost time (te) is exceeded;
Further, after the defrost operation is stopped by the defrost forced stop means (32), the defrost operation prohibiting means (34) for prohibiting the restart of the defrost operation until the reference heating time (tq) elapses. And the defrost forced stop means (3
When defrosting operation is stopped by 2), defrost starting temperature
(Ts) is higher than the temperature at which the defrosting operation was started.
A heat pump multi-system comprising a defrosting start temperature changing means (33) for changing to a temperature . 2. A single heat source side heat exchanger (1) includes a plurality of heat exchangers.
The user side heat exchanger (9) can be connected, and the user side heat exchanger
Circulating the refrigerant from (9) to the heat source side heat exchanger (1)
While performing the heating operation, the temperature of the heat source side heat exchanger (1) is detected.
And a temperature detecting means (18) for outputting the temperature.
8) The detected temperature (Td) is below the defrost start temperature (Ts)
When the heat source side heat exchanger (1) to the use side heat exchanger
(9) Circulating refrigerant to start reverse cycle defrosting operation
Then, the temperature detected by the temperature detecting means (18) (T
When d) exceeds the defrost end temperature (Te), the above defrost operation
With defrosting operation control means (31) for stopping the heat
The operation time of the defrosting operation in the pump multi-system
When (td) exceeds the reference defrost time (te),
A defrost forced stop means (32) for stopping the defrost operation is provided,
Furthermore, the defrost operation is performed by the defrost forced stop means (32).
Is stopped and until the reference heating time (tq) elapses
Prohibit defrosting operation from starting again
Means (34) and the reference heating time (t) for which resumption of the defrosting operation is prohibited by the defrosting operation prohibiting means (34).
After q) has elapsed, the heat pump multi system characterized by forcibly providing a defrosting forced start means for starting the defrosting operation (35).