JP4325455B2 - Air conditioner with defrost function - Google Patents

Description

  The present invention relates to a defrosting device for an air conditioner such as a gas heat pump type air conditioner.

Conventionally, in a gas heat pump or the like that drives a compressor by a gas engine, there has been a problem that the external heat exchanger is frosted during heating.
For example, Patent Document 1 discloses a defrosting method for frost attached to an external heat exchanger during heating. Here, in the conventional technique disclosed in Patent Document 1, the refrigerant discharged from the compressor is caused to flow from the indoor unit through the bypass circuit (open / close valve + pipe) to the inlet side of the outdoor air heat exchanger during heating operation. This is to defrost by increasing the temperature in the outdoor air heat exchanger by joining the refrigerant and raising the temperature and pressure.
As this problem, Patent Document 1 raises the temperature and pressure of the outdoor air heat exchanger inlet refrigerant, so that the refrigerant may be in a liquid state without being completely gasified by the outdoor air heat exchanger. It has been pointed out that there is a risk that the compressor may be sucked in and the compressor may be damaged.

Patent Document 1 proposes two methods to solve the above problem. The first method is a method of completely evaporating the liquid refrigerant after passing through the outdoor air heat exchanger by arranging an engine exhaust heat recovery device in series downstream of the outdoor air heat exchanger.
In the second method, the outlet pipe of the exhaust heat recovery unit is branched in parallel with the outdoor air heat exchanger, each of which is provided with a check valve, one of which merges with the outdoor air heat exchanger outlet, and the other is a four-way switching valve. In the circuit connected to the piping between the indoor unit and the indoor unit, the four-way switching valve is set to the cooling mode, the high-temperature and high-pressure refrigerant gas discharged from the compressor is flowed to defrost the outdoor air heat exchanger, and the outdoor air heat exchanger This is a method of gasifying the liquefied refrigerant in the exhaust heat recovery device and returning it to the compressor.
Japanese Patent Publication No. 2720996

However, the conventional air conditioner defroster has the following problems.
(1) In the case of the first method described in Patent Document 1, by arranging the indoor air heat exchanger and the exhaust heat recovery device in series, the evaporation capacity during the original heating operation is impaired and the operation efficiency is reduced. There is a problem that decreases. The reason is that when the outdoor air heat exchanger and the exhaust heat recovery device are connected in series, the pressure loss due to the refrigerant flow increases, the refrigerant pressure (evaporation temperature) in the upstream outdoor air heat exchanger increases, This is because the temperature difference of the outdoor air heat exchanger refrigerant is reduced, so that the heat exchange efficiency of the outdoor air heat exchanger is reduced. In addition, although the evaporation temperature relatively decreases on the downstream side, the pressure also decreases, so the refrigerant circulation amount of the compressor decreases, and the operation efficiency decreases.

(2) In the case of the second method described in Patent Document 1, the reduction in heat exchange efficiency due to pressure loss is solved by arranging the outdoor air heat exchanger and the exhaust heat recovery device in parallel. During the frost operation, the outdoor air heat exchanger and the exhaust heat recovery chamber are in series as a circuit, and refrigerant is not supplied to the internal unit, so there is a problem that the heating capacity becomes zero and the air conditioning function is not used at all. .

  Then, this invention solves this subject and it aims at providing the air conditioner with a defrosting function with high operating efficiency, maintaining heating capability.

The defroster for an air conditioner of the present invention has the following configuration in order to solve the above problems.
(1) The outdoor air heat exchanger and the exhaust heat recovery unit are arranged in parallel, and the first flow rate adjustment valve is provided on the inlet side of the outdoor air heat exchanger, and the second flow rate adjustment valve is provided on the inlet side of the exhaust heat recovery device. In the air conditioner with a defrost function having a refrigerant circuit in which the discharge side of the compressor and the inlet of the outdoor air heat exchanger are connected via a bypass on-off valve, the bypass on-off valve is a bypass flow rate adjustment valve, Defrost control means for receiving the defrost signal and adjusting the opening of the second flow rate adjustment valve according to the compressor suction superheat degree.
(2) In the air conditioner with a defrost function described in (1), when the second flow rate adjustment valve is greater than or equal to a predetermined opening, the defrost control means opens the opening of the bypass flow rate adjustment valve. It is characterized by adjusting the compressor suction superheat degree.
(3) In the defroster for an air conditioner described in (2), when the bypass flow rate adjustment valve is greater than or equal to a predetermined opening, the defrost control means opens the opening of the first flow rate adjustment valve. It is characterized by adjusting the compressor suction superheat degree.

(4) The outdoor air heat exchanger and the exhaust heat recovery device are arranged in parallel, and the first flow rate adjustment valve is provided on the inlet side of the outdoor air heat exchanger, and the second flow rate adjustment valve is provided on the inlet side of the exhaust heat recovery device. In an air conditioner with a defrost function having a refrigerant circuit in which the discharge side of the compressor and the inlet of the outdoor air heat exchanger are connected via a bypass on-off valve, the flow rate of the indoor outlet is adjusted at the outlet of the indoor air heat exchanger A valve is provided, and defrost control means for receiving a defrost signal and adjusting the opening of the second flow rate adjustment valve according to the compressor suction superheat degree.
(5) In the air conditioner with a defrost function described in (4), when the second flow rate adjustment valve is greater than or equal to a predetermined opening, the defrost control means throttles the opening of the indoor outlet flow rate adjustment valve. It is characterized by adjusting the compressor suction superheat degree.
(6) In the air conditioner with a defrosting function described in (5), when the indoor outlet flow rate adjustment valve has a predetermined opening degree, the defrost control means opens the first flow rate adjustment valve. It is characterized by opening and adjusting the degree.

The gas heat pump type air conditioner of the present invention has the following operations and effects.
First, the operation and effect of the invention according to claims 1 to 3 will be described.
In order to defrost the outdoor air heat exchanger during heating operation, the bypass flow rate adjustment valve of the bypass circuit is opened to the initial opening at the time of defrosting, and the refrigerant discharged from the high temperature and high pressure gas of the compressor is discharged from the expansion mechanism to the outdoor air. Lead between heat exchangers. Here, the liquid refrigerant flowing from the indoor air heat exchanger to the outdoor air heat exchanger does not reduce the amount of heat of the high temperature and high pressure gas of the defrost circuit, which is a heat source for defrosting, so the expansion of the inlet of the outdoor air heat exchanger The first flow rate adjustment valve, which is a mechanism, is fully closed or the flow rate is adjusted by narrowing the opening degree. As a result, the high-temperature and high-pressure refrigerant flowing out of the compressor and flowing into the outdoor air heat exchanger defrosts the outdoor air heat exchanger and liquefies it by dissipating the amount of heat of its own, and the exhaust heat recovery device It merges with the refrigerant at the outlet.

On the other hand, the refrigerant at the outlet of the exhaust heat recovery device is sucked into the compressor so as to have a heat amount (superheat degree) for evaporating the refrigerant liquefied in the outdoor air heat exchanger for defrosting. The opening degree of the second flow rate adjustment valve is adjusted according to the degree of superheat of the refrigerant. As a result, the liquid refrigerant from the outdoor air heat exchanger and the superheated steam refrigerant from the exhaust heat recovery unit merge and exchange heat, so that the refrigerant sucked into the compressor becomes close to saturated gas, and the compressor Liquid compression operation can be prevented.
At this time, when the amount of exhaust heat recovered by the exhaust heat recovery device is large, the second flow rate adjustment valve is opened to lower the degree of superheat.
Furthermore, there is room for increasing the flow rate of the refrigerant flowing through the outdoor air heat exchanger when the opening of the second flow rate adjustment valve reaches the maximum, so that the bypass flow rate depends on the degree of superheat of the refrigerant sucked into the compressor. Increase the defrosting capacity by opening the adjustment valve.
Furthermore, when the opening degree of the bypass flow rate adjustment valve reaches the maximum, there is room for increasing the flow rate of the refrigerant flowing through the outdoor air heat exchanger, so the first flow rate is determined according to the degree of superheat of the refrigerant sucked into the compressor. Open the opening of the regulating valve to increase the refrigerant flow rate of the entire refrigeration cycle and increase the defrosting capacity.

Next, functions and effects of the invention according to claims 4 to 6 will be described.
In order to defrost the outdoor air heat exchanger during heating operation, the bypass flow rate adjustment valve of the bypass circuit is opened to the initial opening at the time of defrosting, and the refrigerant discharged from the high temperature and high pressure gas of the compressor is discharged from the expansion mechanism to the outdoor air. Lead between heat exchangers. Here, the liquid refrigerant flowing from the indoor air heat exchanger to the outdoor air heat exchanger does not reduce the amount of heat of the high temperature and high pressure gas of the defrost circuit, which is a heat source for defrosting, so the expansion of the inlet of the outdoor air heat exchanger The first flow rate adjustment valve, which is a mechanism, is fully closed or the flow rate is adjusted by narrowing the opening degree. As a result, the high-temperature and high-pressure refrigerant flowing out of the compressor and flowing into the outdoor air heat exchanger defrosts the outdoor air heat exchanger and liquefies it by dissipating the amount of heat of its own, and the exhaust heat recovery device It merges with the refrigerant at the outlet.

On the other hand, the refrigerant at the outlet of the exhaust heat recovery device is sucked into the compressor so as to have a heat amount (superheat degree) for evaporating the refrigerant liquefied in the outdoor air heat exchanger for defrosting. The opening degree of the second flow rate adjustment valve is adjusted according to the degree of superheat of the refrigerant. As a result, the liquid refrigerant from the outdoor air heat exchanger and the superheated steam refrigerant from the exhaust heat recovery unit merge and exchange heat, so that the refrigerant sucked into the compressor becomes close to saturated gas, and the compressor Liquid compression operation can be prevented.
At this time, when the amount of exhaust heat recovered by the exhaust heat recovery device is large, the second flow rate adjustment valve is opened to lower the degree of superheat.
Furthermore, there is room for increasing the flow rate of the refrigerant flowing in the outdoor air heat exchanger when the opening degree of the second flow rate adjustment valve becomes maximum, so that the indoor outlet according to the degree of superheat of the refrigerant sucked into the compressor By reducing the opening degree of the flow rate adjustment valve, the flow rate of the bypass flow rate adjustment valve is increased and the defrosting capability is enhanced.
Furthermore, when the opening degree of the indoor outlet flow rate adjustment valve becomes the minimum opening degree, there is room for increasing the flow rate of the refrigerant flowing in the outdoor air heat exchanger, so depending on the degree of superheat of the refrigerant sucked into the compressor The opening degree of the first flow rate adjustment valve is opened, the refrigerant flow rate of the entire refrigeration cycle is increased, and the defrosting capability is enhanced.

Next, the 1st Example of the air conditioner with a defrost function which concerns on this invention is described below, referring drawings. FIG. 1 is a configuration diagram of an air conditioner with a defrosting function of the present embodiment.
The air conditioner includes an outdoor unit 10 that is an outdoor air heat exchanger, an indoor unit 30 that is an indoor air heat exchanger, and a refrigerant circulation passage 1 that circulates between the outdoor unit 10 and the indoor unit 30.
The outdoor unit 10 includes a gas engine 11 for driving the compressors 13A and 13B, an accumulator 12 that stores the refrigerant in a state where the gaseous refrigerant and the liquid refrigerant are separated, and heat exchange of the refrigerant for air conditioning. It has the outdoor heat exchanger 14 which performs. A synchronous motor 52 that is a generator is connected to the gas engine 11. In the outdoor unit 10, an exhaust heat recovery device 24 is arranged in parallel. An outdoor unit valve 25 that is a first flow rate adjusting valve is provided at the inlet of the outdoor unit 10. An exhaust heat recovery valve 26 that is a second flow rate adjustment valve is provided at the inlet of the exhaust heat recovery device 24.
The indoor unit 30 includes an indoor heat exchanger 31 that performs heat exchange between indoor air and a refrigerant, and an expansion valve 32 that expands the refrigerant.
The compressor 13 sucks gaseous refrigerant and discharges high-pressure gaseous refrigerant. A bypass pipe 28 from the outlet of the compressor 13 is connected to the pipe between the outdoor unit 10 and the outdoor unit valve 25. A bypass flow rate adjustment valve 29 is provided in the middle of the bypass pipe 28.

Next, the operation when the room is cooled will be described. The gas engine 11 is driven by the fuel gas, and the compressors 13A and 13B are driven. The compressors 13A and 13B suck and compress the gaseous refrigerant of the accumulator 12 and discharge it as a high-temperature and high-pressure gas. The discharged gaseous refrigerant is separated from the refrigerant in the oil separator 19. The refrigerant from which the oil has been separated flows into the outdoor heat exchanger 14 through the four-way valve 17.
The high-temperature and high-pressure gaseous refrigerant is cooled and liquefied by the outdoor heat exchanger 14. The liquefied refrigerant is expanded in the expansion valve 32 via the filter dryer 22, the ball valve 23, and the strainer 31n, and becomes a low temperature.
The low-temperature refrigerant reaches the indoor heat exchanger 31 through the strainer 31m, cools the indoor air, and then returns to the accumulator 12. The refrigerant is stored in the accumulator 12 in a state of being separated into a liquid refrigerant and a gaseous refrigerant.

Next, the operation when the room is heated will be described. The gas engine 11 is driven by the fuel gas, and the compressors 13A and 13B are driven. The compressors 13A and 13B suck and compress the gaseous refrigerant of the accumulator 12 and discharge it as a high-temperature and high-pressure gas. The discharged gaseous refrigerant is separated from the refrigerant in the oil separator 19. The refrigerant from which the oil has been separated flows into the indoor heat exchanger 31 through the four-way valve 17. The high-temperature and high-pressure refrigerant heats indoor air in the indoor heat exchanger 17.
Next, the refrigerant is expanded by the expansion valve 32 through the strainer 31m, and reaches the outdoor heat exchanger 14 through the ball valve 23 and the filter dryer 22. Then, it returns to the accumulator 12 through the four-way valve 17.

The defrosting function that is a feature of the present invention will be described. Devices related to the defrosting function are shown in FIGS. Although it repeats in part, the operation of each device will be explained. During indoor heating, the high-temperature and high-pressure gas refrigerant discharged from the compressor 13 is guided to the indoor unit 31 by the four-way switching valve 17, and dissipates heat by exchanging heat with indoor air in the indoor unit 31. Becomes a refrigerant. The liquid refrigerant is depressurized by the expansion valve 32 of the indoor unit 31 to become an intermediate pressure and intermediate temperature, and then is divided and the outdoor unit valve 25 that is a flow rate adjusting valve of the outdoor unit 14 arranged in parallel, and the exhaust heat recovery unit 24. The exhaust heat recovery valve 26, which is a flow rate adjustment valve, is further depressurized to enter a low-pressure low-temperature gas-liquid two-phase state. The outdoor heat exchanger 14 and the exhaust heat exchanger 24 absorb heat by heat exchange and become a low-pressure and low-temperature gas state. Next, it is sucked into the compressor 13 and the cycle is repeated.
On the other hand, the high-pressure high-temperature gas refrigerant of the compressor 13 is connected between the outdoor unit 14 and the outdoor unit valve 25 via a bypass flow rate adjustment valve 29 and a bypass pipe 28.

Next, the defrosting action will be described. FIG. 3 shows the state of the system when performing the defrosting action. FIG. 4 shows the configuration of a system for performing the defrosting action.
The control device 40 has a CPU 41, a RAM 42, and a ROM 43. The ROM 43 stores a defrosting operation program 431 and a compressor inlet superheat degree calculation program 432.
The control device 40 includes an outlet refrigerant temperature sensor 44 for measuring the temperature of the refrigerant that has exited the outdoor unit 14, an outdoor temperature sensor 45 for measuring the outdoor temperature, and an indoor temperature sensor 46 for measuring the indoor temperature. Connected. Further, the control device 40 adjusts the opening degree of the flow rate control means 25A for adjusting the opening degree of the outdoor unit valve 25, the flow rate control means 26A for adjusting the opening degree of the exhaust heat exchanger valve 26, and the opening degree of the bypass flow rate adjusting valve 29. The flow control means 29A to perform and the indoor expansion valve 32 are connected.

Next, the defrosting operation program 431 will be described. 5 to 7 show a first embodiment of the defrosting operation program 431. FIG. Control when the defrost signal is turned on is shown below. Hereinafter, the relationship between the predetermined temperatures is T1 <T2 <T3 <T4 <T5 <T6. Further, the defrosting operation program outputs a defrost signal when the outlet refrigerant temperature of the outdoor unit 14 is −3 to −2 degrees Celsius and the outside air temperature−evaporation temperature = temperature difference is 7 to 8 degrees or more. There is also a program to issue.
When the defrost signal is turned on, the exhaust heat recovery valve 26 is set to the initial opening during defrosting (a larger opening than normal) (S12), and the bypass flow regulating valve 29 is set to the initial opening during defrosting (standard). The degree of opening of the outdoor unit valve 25 is set to the initial opening degree (closed state) during defrosting (S31).
When the defrost signal is ON (S13; YES), the compressor intake superheat degree T is obtained by the compressor inlet superheat degree calculation program 432. Although a detailed description of the compressor inlet superheat degree calculation program 432 is omitted, the superheat degree T is obtained from the measured compressor inlet temperature and pressure using a vapor pressure diagram.
When the superheat degree T is smaller than the predetermined value T1 (S14; YES), the opening degree of the exhaust heat recovery valve 26 is decreased (S17). The opening degree of the exhaust heat recovery valve 26 is decreased until the degree of superheat T becomes equal to or greater than the predetermined value T1 (S18).
When the superheat degree T is not smaller than the predetermined value T1 (S14; NO) and when the superheat degree T is equal to or greater than the predetermined value T2 (S15; YES), the opening degree of the exhaust heat recovery valve 26 is increased (S19). The degree of opening of the exhaust heat recovery valve 26 is increased until the degree of superheat T is less than the predetermined value T2 (S20).

Further, when the exhaust heat recovery valve 26 has the maximum opening and the superheat degree T is equal to or higher than the predetermined temperature T4 (S23; YES), the opening of the bypass flow rate adjustment valve 29 is increased (S26). The opening degree of the bypass flow rate adjustment valve 29 is increased until the degree of superheat T is less than the predetermined value T4 (S27).
When the superheat degree T is not larger than the predetermined value T4 (S23; NO) and when the superheat degree T is less than the predetermined value T3 (S24; YES), the opening degree of the bypass flow rate adjustment valve 29 is decreased (S28). The opening degree of the bypass flow rate adjustment valve 29 is decreased until the degree of superheat T becomes equal to or greater than the predetermined value T3 (S29).
When the exhaust heat recovery valve 26 and the bypass flow rate adjustment valve 29 are at the maximum opening and the superheat degree T is equal to or higher than the predetermined temperature T6 (S33; YES), the opening of the outdoor unit valve 25 is increased (S36). ). The opening degree of the outdoor unit valve 25 is increased until the degree of superheat T is less than the predetermined value T6 (S37).
When the superheat degree T is smaller than the predetermined value T6 (S33; NO) and when the superheat degree T is less than the predetermined value T5 (S34; YES), the opening degree of the outdoor unit valve 25 is decreased (S38). The degree of opening of the outdoor unit valve 25 is decreased until the degree of superheat T becomes equal to or greater than the predetermined value T5 (S39).
When the defrost signal is turned off (S13; NO, S22; NO, S32; NO), the operation returns to the normal operation control (S16, S25, S35).

The operation and effect of the defrosting operation program will be described.
In order to defrost the outdoor air heat exchanger during heating operation, the bypass flow rate adjustment valve 29 of the bypass circuit is opened to the initial opening during defrosting, and the refrigerant discharged from the high-temperature and high-pressure gas of the compressor 13 is discharged to the outdoor unit valve. 25 to the pipe between the outdoor unit 14. Here, the liquid refrigerant flowing from the indoor unit 31 to the outdoor unit 14 does not reduce the amount of heat of the high-temperature and high-pressure gas in the defrost circuit, which is a heat source for defrosting, so the outdoor unit valve that is an expansion valve at the inlet of the outdoor unit 14 Adjust the flow rate by fully closing 25 or narrowing the opening degree small. As a result, the high-temperature and high-pressure refrigerant that flows out of the compressor 13 and flows into the outdoor unit 14 defrosts the outdoor unit 14 by dissipating the amount of heat of its own, and is liquefied, and the outlet of the exhaust heat recovery unit 24 It merges with the refrigerant.

On the other hand, the refrigerant at the outlet of the exhaust heat recovery unit 24 is sucked into the compressor 13 so as to have a heat amount (superheat degree) for evaporating the refrigerant liquefied in the outdoor unit 14 for defrosting. The opening degree of the exhaust heat recovery valve 26 is adjusted according to the degree of superheat of the refrigerant. Thereby, the liquid refrigerant from the outdoor unit 14 and the superheated vapor refrigerant from the exhaust heat recovery unit 24 merge and exchange heat, whereby the refrigerant sucked into the compressor 13 becomes close to saturated gas, and the compressor 13 The liquid compression operation can be prevented.
At this time, if the amount of exhaust heat recovered by the exhaust heat recovery unit 24 is large, the exhaust heat recovery unit valve 26 is opened to lower the degree of superheat.
Furthermore, when the opening degree of the exhaust heat recovery valve 26 becomes the maximum, there is room for increasing the flow rate of the refrigerant flowing through the outdoor unit 14, and therefore, the bypass flow rate according to the degree of superheat of the refrigerant sucked into the compressor 13. The opening degree of the regulating valve 29 is opened to increase the defrosting capacity.
Further, when the opening degree of the bypass flow rate adjustment valve 29 is also maximized, there is room for increasing the flow rate of the refrigerant flowing through the outdoor unit 14, and therefore the outdoor unit valve according to the degree of superheat of the refrigerant sucked into the compressor 13. The opening of 25 is opened, the refrigerant | coolant flow rate of the whole refrigerating cycle is increased, and defrosting capability is improved.

  As described in detail above, according to the air conditioner with a defrosting function of the present embodiment, the outdoor unit 14 and the exhaust heat recovery unit 24 are arranged in parallel, and the outdoor unit valve 25 is provided on the inlet side of the outdoor unit 14. Is provided with a waste heat recovery valve 26 on the inlet side of the exhaust heat recovery device, and has a defrosting function air having a refrigerant circuit in which the discharge side of the compressor 13 and the inlet of the outdoor unit 14 are connected via a bypass opening / closing valve. In the conditioner, the bypass opening / closing valve is the bypass flow rate adjustment valve 29, and a defrosting operation program 431 that receives the defrosting signal and adjusts the opening degree of the exhaust heat recovery valve 26 according to the compressor suction superheat degree. Therefore, when the liquid refrigerant from the outdoor unit 14 and the superheated vapor refrigerant from the exhaust heat recovery unit 24 merge and exchange heat, the refrigerant sucked into the compressor 13 becomes close to saturated gas, and the compressor 13 The liquid compression operation can be prevented.

Further, when the exhaust heat recovery valve 26 is fully open, the defrosting operation program 431 opens and adjusts the opening of the bypass flow rate adjustment valve 29, so that the bypass is made according to the degree of superheat of the refrigerant sucked into the compressor 13. The opening degree of the flow control valve 29 is opened to increase the defrosting capacity.
Further, when the bypass flow rate adjustment valve 29 is fully open, the defrosting operation program 431 opens and adjusts the opening degree of the outdoor unit valve 25, so that the outdoor unit valve 25 corresponds to the degree of superheat of the refrigerant sucked into the compressor. To increase the refrigerant flow rate of the entire refrigeration cycle and increase the defrosting capacity.

Next, a second embodiment of the defrosting operation program is shown in FIGS. In the second embodiment, the bypass flow rate adjustment valve 29 is a simple on-off valve, and the indoor expansion valve 32 that is the indoor outlet flow rate adjustment valve is used as the indoor expansion valve.
The exhaust heat recovery valve 26 is set to an initial opening during defrosting (a larger opening than normal) (S42), the bypass flow path adjustment valve 29 is opened (S51), and the outdoor unit valve 25 is initially opened during defrosting. Degree (closed state) (S61).
When the defrost signal is ON (S43; YES), the compressor intake superheat degree T is obtained by the compressor inlet superheat degree calculation program 432.
When the superheat degree T is smaller than the predetermined value T1 (S44; YES), the opening degree of the exhaust heat recovery valve 26 is decreased (S47). The degree of opening of the exhaust heat recovery valve 26 is decreased until the degree of superheat T becomes equal to or greater than the predetermined value T1 (S48).
When the superheat degree T is not smaller than the predetermined value T1 (S44; NO), and when the superheat degree T is equal to or greater than the predetermined value T2 (S45; YES), the opening degree of the exhaust heat recovery valve 26 is increased (S49). The degree of opening of the exhaust heat recovery valve 26 is increased until the degree of superheat T is less than the predetermined value T2 (S50).

If the exhaust heat recovery valve 26 has the maximum opening and the superheat degree T is smaller than the predetermined temperature T4 (S53; YES), the opening of the indoor expansion valve 32 is decreased (S56). The opening degree of the indoor expansion valve 32 is decreased until the degree of superheat T becomes less than the predetermined value T4 (S57).
When the superheat degree T is not larger than the predetermined value T4 (S53; NO) and when the superheat degree T is less than the predetermined value T3 (S54; YES), the opening degree of the indoor expansion valve 32 is increased (S58). The opening degree of the indoor expansion valve 32 is increased until the degree of superheat T becomes equal to or greater than the predetermined value T3 (S59).
Further, when the exhaust heat recovery valve 26 is at the maximum opening, the indoor expansion valve 32 is at the minimum opening, and the superheat T is equal to or higher than the predetermined temperature T6 (S63; YES), the opening of the outdoor unit valve 25 is increased. (S66). The degree of opening of the outdoor unit valve 25 is increased until the degree of superheat T is less than the predetermined value T6 (S67).
When the superheat degree T is smaller than the predetermined value T6 (S63; NO) and when the superheat degree T is less than the predetermined value T5 (S64; YES), the opening degree of the outdoor unit valve 25 is decreased (S68). The opening degree of the outdoor unit valve 25 is decreased until the degree of superheat T becomes equal to or greater than the predetermined value T5 (S69).
When the defrost signal is turned off (S43; NO, S52; NO, S62; NO), the operation returns to the normal operation control (S46, S55, S65).

  In order to defrost the outdoor unit 14 during the heating operation, the bypass on-off valve 29 of the bypass circuit is opened, and the refrigerant discharged from the high-temperature and high-pressure gas of the compressor 13 is connected to the pipe between the outdoor unit valve 25 and the outdoor unit 14. Lead. Here, the liquid refrigerant flowing from the indoor unit 31 to the outdoor unit 14 does not reduce the amount of heat of the high-temperature and high-pressure gas in the defrost circuit, which is a heat source for defrosting. The valve 25 is fully closed or the flow amount is adjusted by reducing the opening degree. As a result, the high-temperature and high-pressure refrigerant that flows out of the compressor 13 and flows into the outdoor unit 14 defrosts the outdoor unit 14 by dissipating the amount of heat of its own, and is liquefied, and the outlet of the exhaust heat recovery unit 24 It merges with the refrigerant.

On the other hand, the refrigerant at the outlet of the exhaust heat recovery device 14 is sucked into the compressor 13 so as to have a heat quantity (superheat degree) for evaporating the refrigerant liquefied in the outdoor unit 14 for defrosting. The opening degree of the exhaust heat recovery valve 26 is adjusted according to the degree of superheat of the refrigerant. Thereby, the liquid refrigerant from the outdoor unit 14 and the superheated vapor refrigerant from the exhaust heat recovery unit 24 merge and exchange heat, whereby the refrigerant sucked into the compressor 13 becomes close to saturated gas, and the compressor 13 The liquid compression operation can be prevented.
At this time, if the amount of exhaust heat recovered by the exhaust heat recovery unit 24 is large, the exhaust heat recovery unit valve 26 is opened to lower the degree of superheat.
Furthermore, when the opening degree of the exhaust heat recovery valve 26 reaches the maximum, there is room for increasing the flow rate of the refrigerant flowing through the outdoor air heat exchanger, so that it depends on the degree of superheat of the refrigerant sucked into the compressor 13. By restricting the opening degree of the indoor expansion valve 32, the flow rate of the bypass opening / closing valve 29 is increased and the defrosting capability is enhanced.
Furthermore, when the opening degree of the indoor expansion valve 32 reaches the minimum opening degree, there is room for increasing the flow rate of the refrigerant flowing through the outdoor unit 14, so that the outdoor unit depends on the degree of superheat of the refrigerant sucked into the compressor 13. The opening degree of the valve 25 is opened to increase the refrigerant flow rate of the entire refrigeration cycle, thereby increasing the defrosting capacity.

  As described above in detail, according to the air conditioner with a defrosting function of the second embodiment, the outdoor unit 14 and the exhaust heat recovery unit 24 are arranged in parallel, and the outdoor unit is disposed on the inlet side of the outdoor unit 14. A defrosting function having a refrigerant circuit in which an exhaust heat recovery valve 26 is provided on the inlet side of the exhaust heat recovery device and the discharge side of the compressor 13 and the inlet of the outdoor unit 14 are connected via a bypass opening / closing valve. In the attached air conditioner, an indoor expansion valve 32 is provided at the outlet of the indoor unit 31, and a defrosting operation is performed in which the defrost signal is received and the opening degree of the exhaust heat recovery valve 26 is adjusted according to the compressor suction superheat degree. Since the program has the liquid refrigerant from the outdoor air heat exchanger and the superheated steam refrigerant from the exhaust heat recovery unit merge and exchange heat, the refrigerant sucked into the compressor 13 becomes close to saturated gas, The liquid compression operation of the compressor 13 can be prevented.

Further, when the exhaust heat recovery valve 26 is fully opened, the defrosting operation program 431 adjusts by narrowing the opening of the indoor expansion valve 32, so that the indoor expansion is performed according to the degree of superheat of the refrigerant sucked into the compressor 13. By restricting the opening degree of the valve 32, the flow rate of the bypass flow rate adjustment valve is increased and the defrosting capability is enhanced.
Furthermore, when the opening degree of the indoor expansion valve 32 reaches the minimum opening degree, there is room for increasing the flow rate of the refrigerant flowing through the outdoor unit 14, so that the outdoor unit depends on the degree of superheat of the refrigerant sucked into the compressor 13. The opening degree of the valve 25 is opened to increase the refrigerant flow rate of the entire refrigeration cycle, thereby increasing the defrosting capacity.

As mentioned above, although one Example of the gas heart pump type air conditioning apparatus concerning this invention was described, this invention is not limited to this, A various change is possible in the range which does not deviate from the meaning.
For example, in the first embodiment, the indoor expansion valve 32 is an on-off valve and the bypass flow rate adjustment valve 29 is a flow rate adjustment valve. In the second embodiment, the indoor expansion valve 32 is a flow rate adjustment valve and the bypass flow rate adjustment valve 29 is used. However, both the indoor expansion valve 32 and the bypass flow rate adjustment valve 29 may be used as flow rate adjustment valves.
Moreover, although the present Example demonstrated the gas heat pump type air conditioner, if EHP is used, this invention can be implemented if an external heat source is used.

It is a block diagram of the air conditioner with a defrost function. It is a figure which shows the state of the system at the time of heating operation. It is a figure which shows the state of the system at the time of a defrost operation. It is a block diagram which shows the structure of control. It is a 1st flowchart which shows the defrost operation program of 1st Example. It is a 2nd flowchart which shows the defrost operation program of 1st Example. It is a 3rd flowchart which shows the defrost operation program of 1st Example. It is a 4th flowchart which shows the defrost operation program of 2nd Example. It is a 5th flowchart which shows the defrost operation program of 2nd Example. It is a 6th flowchart which shows the defrost operation program of 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Gas engine 13 Compressor 14 Outdoor unit 24 Exhaust heat recovery device 25 Outdoor unit valve 26 Exhaust heat recovery device valve 28 Bypass piping 29 Bypass flow control valve 31 Indoor unit 32 Indoor expansion valve 431 Defrosting operation program

Claims (2)

An outdoor air heat exchanger and an exhaust heat recovery device are arranged in parallel, and a first flow rate adjustment valve is provided on the inlet side of the outdoor air heat exchanger, and a second flow rate adjustment valve is provided on the inlet side of the exhaust heat recovery device. In the air conditioner with a defrost function having a refrigerant circuit in which the discharge side of the compressor and the inlet of the outdoor air heat exchanger are connected via a bypass on-off valve,
The bypass on-off valve is a bypass flow rate adjustment valve,
Receiving a defrost signal, and having a defrost control means for adjusting the opening of the second flow rate adjustment valve according to the compressor suction superheat degree ,
When the second flow rate adjustment valve is greater than or equal to a predetermined opening, the defrosting control means opens the opening of the bypass flow rate adjustment valve to adjust the compressor suction superheat degree;
When the bypass opening and closing valve is greater than or equal to a predetermined opening, the defrosting control means opens the opening of the first flow rate adjustment valve to adjust the compressor intake superheat degree;
An air conditioner with a defrosting function. An outdoor air heat exchanger and an exhaust heat recovery device are arranged in parallel, and a first flow rate adjustment valve is provided on the inlet side of the outdoor air heat exchanger, and a second flow rate adjustment valve is provided on the inlet side of the exhaust heat recovery device. In the air conditioner with a defrost function having a refrigerant circuit in which the discharge side of the compressor and the inlet of the outdoor air heat exchanger are connected via a bypass on-off valve,
An indoor outlet flow rate adjustment valve is provided at the outlet of the indoor air heat exchanger,
Receiving a defrost signal, and having a defrost control means for adjusting the opening of the second flow rate adjustment valve according to the compressor suction superheat degree ,
When the second flow rate adjustment valve is greater than or equal to a predetermined opening, the defrosting control means adjusts the compressor intake superheat degree by reducing the opening of the indoor outlet flow rate adjustment valve;
When the indoor outlet flow rate adjustment valve reaches a predetermined opening degree, the defrosting control means opens and adjusts the opening degree of the first flow rate adjustment valve;
An air conditioner with a defrosting function.

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