JP3463537B2 - Air conditioner - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an air conditioner,
Especially as a global environment protection, there is no fear of ozone layer destruction,
It is suitable for efficiently performing defrosting required during heating operation.

[0002]

2. Description of the Related Art In an air conditioner of a conventional heat pump type refrigeration cycle, an outdoor fan is operated at a low speed every time a predetermined time elapses after a heating operation is started to determine defrosting,
Still, it is known to start the defrosting operation when the temperature of the outdoor heat exchanger drops, for example, as described in JP-A-9-196522.

[0003]

In order to protect the global environment, HCFC (Hydrochlorofluorocar) which is a conventional refrigerant is used.
bon) system (eg R22), an alternative refrigerant HFC
It is desirable to use a (Hydrofluorocarbon) type refrigerant (for example, R407C). However, since the physical properties of the refrigerant are different in the above conventional technology, the determination value of the outdoor heat exchanger temperature for starting defrosting becomes unstable depending on the type of refrigerant, and there is a problem in reliability.

An object of the present invention is to solve the above problems and to provide an air conditioner having a simple structure which is excellent in reliability and stability without fear of depleting the ozone layer as a global environment protection. .

[0005]

In order to solve the above problems, the present invention provides an outdoor unit having a compressor, a four-way valve, an outdoor heat exchanger and an outdoor expansion valve, an indoor expansion valve and an indoor heat exchanger. In an air conditioner equipped with a refrigeration cycle in which an indoor unit having a pipe is connected, a detection means for detecting the heat exchanger temperature, a setting means for setting the type of refrigerant enclosed in the refrigeration cycle, and a setting It is provided with means for calculating a judgment value of the outdoor heat exchanger temperature according to the type of refrigerant set by the means, and means for starting defrosting by the judgment value.

The means for starting defrosting means, for example, an operation suitable for defrosting when moisture in the air becomes frost and adheres to the outdoor heat exchanger during heating operation of the air conditioner. Means to start. Specifically, during heating operation, the four-way valve is switched, and in the same way as in cooling operation, high-pressure and high-temperature refrigerant is allowed to flow into the outdoor heat exchanger (reverse cycle defrosting), and the outdoor heat exchanger is discharged from the vicinity of the compressor outlet. This can be achieved by means of opening / closing a circuit bypassing to (2) and causing high-temperature refrigerant to flow into the outdoor heat exchanger (hot gas defrosting). As a result, the defrosting operation is started by changing the determination value of the outdoor heat exchanger temperature for each type of refrigerant, so that reliability and stability can be improved and power consumption can be saved.

Further, in the invention described above, it is desirable that a setting means for setting an HFC type refrigerant as a kind of the refrigerant is provided. As a result, as a global environment protection, there is no fear of ozone layer destruction and the reliability and stability can be made excellent.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. 1 is a graph showing the relationship between the outdoor air temperature and the temperature of the outdoor heat exchanger that starts defrosting, FIG. 2 is a block diagram showing the main configuration of the air conditioner according to the present invention, and FIG. 3 is the type of refrigerant. The graph which shows the heat exchanger liquid side temperature (refrigerant evaporation temperature) with respect to each outdoor air temperature, FIG. 4 is a flowchart which shows the method until the defrosting operation by this invention is started.

In FIG. 2, the air conditioner is provided in the outdoor unit 3.
Units or multiple indoor units 111, 11N are connected,
The outdoor unit 3 and the indoor units 111 and 11N form a closed circuit, and the closed circuit has a refrigeration cycle in which a refrigerant is sealed. In the air conditioner of the heat pump refrigeration cycle, when the outdoor air temperature decreases during heating operation, the refrigerant in the outdoor heat exchanger is less likely to evaporate, and the evaporation pressure and evaporation temperature of the refrigerant decrease. Therefore, the condensing temperature of the air that is performing heat exchange also decreases, and the moisture in the air adheres to the surface of the outdoor heat exchanger as frost, so it is necessary to defrost the frost.

Defrosting is judged, for example, when the outdoor air temperature is lower than a certain value, and after a certain period of time, the outdoor heat exchanger liquid side temperature drops to a certain temperature. There is something to do, which starts defrosting.

In the defrosting method, the four-way valve is switched to bring the refrigerant into the same normal circulation direction as in the cooling operation, and reverse cycle defrosting in which a high-pressure and high-temperature refrigerant flows into the outdoor heat exchanger, and the outdoor heat is discharged from the vicinity of the discharge port of the compressor. BACKGROUND ART Hot gas defrosting or the like in which a high-temperature refrigerant is made to flow by opening and closing a bypass circuit that bypasses a exchanger is known.

In the outdoor unit 3, one or a plurality of units each having a variable drive frequency, the outdoor heat exchanger 5 and the outdoor expansion valve 10 are connected by piping, and the outdoor heat exchanger 5 is connected.
An outdoor fan 6 is provided for blowing air. In addition, the indoor unit 1
Reference numerals 11 and 11N sequentially connect the indoor heat exchangers 121 and 12N for exchanging heat with the indoor air and the indoor expansion valves 141 and 14N for adjusting the flow rate of the refrigerant of the indoor heat exchangers 121 and 12N, respectively, and perform indoor heat exchange. The indoor fans 131 and 13N are provided for blowing air to the devices 121 and 12N.

The outdoor unit 3 includes an accumulator 7 and a four-way valve 8.
And a receiver 9. The gas side and the liquid side of the outdoor unit 3 and the indoor units 111 and 11N are connected by the gas side pipe 15, the liquid side pipe 16 and the branch pipes 171 and 17N to form a closed circuit. Refrigerant is sealed inside.

Further, an outdoor air temperature detector 18 for detecting an outdoor air temperature, an outdoor heat exchanger liquid side temperature detector 19 for detecting an outdoor heat exchanger liquid side temperature, an outdoor heat exchanger gas side temperature detector 20, Refrigerant discharge temperature detector 21, Refrigerant suction pressure detector 22 for detecting refrigerant suction pressure, Refrigerant discharge pressure detector 23 for detecting refrigerant discharge pressure, Compressor power consumption detector 24 for detecting power consumption of the compressor 4, The outdoor fan power consumption detector 25, which detects the power consumption of the outdoor fan 6, the compressor 4
An inverter compressor drive frequency operator 26 for operating the frequency of the outdoor fan, an outdoor fan air blowing capacity operator 27 for operating the air blowing capacity of the outdoor fan 6, and an outdoor expansion valve opening operator 28 for operating the opening of the outdoor expansion valve 10. A four-way valve operator 29 that performs an operation of switching the refrigerant direction of the four-way valve 7, indoor air temperature detectors 301 and 30N that detect the indoor air temperature of the use portion, and blown air temperature detection that detects the blown air temperature to the use portion. Indoor fan power consumption detectors 341, 34 for detecting electric power of the appliances 311, 31N and the indoor fans 141, 14N
N, indoor fan blowing capacity operation devices 351 and 35N for controlling the blowing capacity of the indoor fans 141 and 14N, and the indoor expansion valve 1
Indoor expansion valve opening operation devices 361 and 36N for operating the refrigerant circulation amount of 41 and 14N, storing a preset temperature and humidity set value, or a remote control air temperature and humidity setting for the user to set a desired temperature and humidity Devices 371, 37N and the like are provided.

Further, it has a refrigerant type setting device 38 as a setting means for inputting and setting a refrigerant type, and an arithmetic unit 39 for calculating a judgment value for judging the start of the defrosting operation according to the refrigerant kind. There is. Further, the control device 40 reads these detection signals and operates the operation devices 26, 27, 28, 29, 3 and.
It is wired so as to calculate and control the manipulated variables 51, 35N, 361, 36N.

In the above-mentioned air conditioner, the compressor 4 is activated and performs a compression action, whereby the enclosed refrigerant is compressed and overheated, and the outdoor heat exchanger 5 is used for cooling, the indoor heat exchanger 121 is used for heating, It flows in the direction of 12N. Therefore, the air is cooled and liquefied by the outdoor air during cooling and by the indoor air during heating, and heat is given to the air. Furthermore, by passing through the expansion valves 10, 141, and 14N that perform expansion, the pressure is reduced and supercooled, and flows into the indoor heat exchanger during cooling and into the outdoor heat exchanger during heating. Therefore, the air is heated and evaporated by the indoor air during cooling and by the outdoor air during heating, so that the heat is taken from the air. The evaporated refrigerant again flows into the compressor and is compressed, and the above operation is repeated. This is a series of behaviors of the refrigerant in the air conditioner.

The arithmetic and control unit controls the temperature and humidity of the indoor air, and also controls the temperature and pressure of the refrigerant of the air conditioner which is the heat load unit, judges the start of defrosting, defrosts and the like. During heating, the air conditions used are generally lower than during cooling, and the temperature at which the evaporating action is performed is around 0 ° C.,
Moisture of the air condensed by heat exchange is frozen and frost forms on the surface of the outdoor heat exchanger. The frosted frost lowers the heat transfer coefficient of the heat exchanger and further lowers the refrigerant evaporation temperature, so the compressor suction pressure decreases and the heating capacity decreases. Therefore,
If the frosted state is left as it is, the cooling cycle becomes very unfavorable. Therefore, defrosting is performed. When defrosting, it is necessary to judge that the outdoor heat exchanger is frosted. This determination is made based on, for example, the outdoor air temperature, the elapsed time, and the outdoor heat exchanger liquid side temperature.

However, when a different refrigerant such as an alternative refrigerant is used, it is not preferable to use the conventional defrosting judgment as it is because of the difference in the physical properties of the refrigerant. Therefore, the difference between the conventional HCFC refrigerant R22 and the HFC alternative refrigerant R407C will be described as an example.

To determine the start of defrosting, it is preferable to make a determination based on the outdoor air temperature, the elapsed time, and the temperature of the outdoor heat exchanger liquid side, but it is preferable to perform the determination of the outdoor heat exchanger (liquid side) temperature.

When the dryness of a single refrigerant such as R22 is 0 or more and 1 or less, the temperature inside the outdoor heat exchanger is constant,
Heat exchanger inlet temperature = heat exchanger outlet temperature. But,
In reality, there is a pressure loss, so the outlet temperature is slightly lower. Then, the non-azeotropic mixed refrigerant such as R407C is further different.

R407C is R32, R125, R13
In the three-component mixed refrigerant 4a, R134a has a higher boiling point than R32 and R125 which have close boiling points, and a temperature gradient occurs in evaporation and condensation. That is, in the evaporation process, the difference between the heat exchanger inlet temperature <the heat exchanger outlet temperature occurs. Therefore, the temperature of the heat exchanger liquid side at the time of determining the defrosting must be newly corrected.

FIG. 3 is a simulation of the refrigerant evaporation temperature with respect to the outdoor air temperature of R22 and R407C. However, this is the temperature near the inlet (liquid side) of the heat exchanger. The conditions for the refrigeration cycle include the compressor drive frequency,
The discharge superheat was the same for both R22 and R407C.

According to FIG. 3, due to the difference in the physical properties of the refrigerant, the temperature 41 on the liquid side of the heat exchanger is 41 from R407C and 40 from R22.
It can be seen that the temperature becomes lower by about 2 ° C. At this time, since the average temperature of the liquid side and the average temperature of the gas side of the heat exchanger are almost the same, when detecting the defrosting start by detecting the temperature of the heat exchanger liquid side, the temperature of the heat exchanger liquid side It is enough to lower the judgment value by 2 ° C from that of R22. The defrosting operation thereafter may be performed by conventionally known reverse cycle defrosting, hot gas bypass defrosting, or the like.

An example in which the heat exchanger (liquid side) determination temperature is set is shown in FIG. 1, and the determination value of the heat exchanger liquid side temperature, which is one of the determination factors for the start of defrosting, is compared with the outdoor air temperature. It is a plot. 1 is the judgment value of R22, 2 is R40
It is a judgment value of 7C. The temperature difference between 1 and 2 is set by the difference in the physical property values shown in FIG. In addition, it is good to judge which kind of refrigerant is filled so that any kind of new HFC refrigerant may be filled. Since the heat exchanger liquid-side temperature has different values, it is necessary to set the outdoor heat exchanger liquid-side temperature judgment values used for the defrosting start judgment to different values.

The setting device 38 shown in FIG. 2 capable of changing the type of the enclosed refrigerant is preferably a dip switch or dial switch which is set by a service person, or a remote controller which can be changed by the user. The defrosting determination value is changed by this refrigerant type set value and the calculation of the calculation device. As a result, it is possible to perform defrosting corresponding to various physical properties of the refrigerant with one product without changing the contents of the control device for each product.

FIG. 4 shows a procedure for judging the refrigerant type and changing the judgment value. Generally, before operating the air conditioner, the type of the enclosed refrigerant is set by the refrigerant type setting device 38 (step 43). Then, the air conditioner is operated (step 44). The operation device 39 reads the refrigerant type instructed from the refrigerant type setting unit 38 (step 45). The calculation device calculates and outputs a determination value according to the set refrigerant type (step 46), and changes the defrosting determination value in the control device 40 (step 47). Then, the refrigeration cycle operation control is performed (step 48). Thereafter, it is constantly monitored whether there is a stop command (step 49). When the stop command is issued, the operation is stopped as it is (step 51), and when the operation is continued, it is confirmed whether the refrigerant type is changed (step 50). If there is a change, the process returns to the refrigerant type reading 45, and if not, the refrigeration cycle operation is continued.

As described above, the defrosting is optimally performed by setting the judgment values, such as the temperature of the outdoor heat exchanger liquid side, necessary for starting the defrosting to correspond to the physical properties of the new refrigerant. It becomes possible. Further, by judging the enclosed refrigerant and changing it to an appropriate value, one kind of product can cope with various kinds of refrigerants.

[0028]

According to the present invention, since the defrosting operation is started by changing the judgment value of the outdoor heat exchanger temperature for each type of refrigerant, reliability and stability are improved, and power saving is achieved. An air conditioner can be obtained. Also, in the above,
By providing the setting means for setting the HFC type refrigerant as the kind of the refrigerant, it is possible to obtain the air conditioner excellent in reliability and stability without fear of depleting the ozone layer as global environment protection.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between an outdoor air temperature and an outdoor heat exchanger temperature at which defrosting is started.

FIG. 2 is a block diagram showing a main configuration of an air conditioner according to an embodiment.

FIG. 3 is a graph showing heat exchanger liquid side temperature (refrigerant evaporation temperature) with respect to outdoor air temperature for each type of refrigerant.

FIG. 4 is a flowchart showing a method for starting a defrosting operation according to an embodiment.

[Explanation of symbols]

3 ... outdoor unit, 4 ... compressor, 5 ... outdoor heat exchanger, 6 ... outdoor fan, 7 ... accumulator, 8 ... four-way valve, 9 ... receiver, 10 ... outdoor expansion valve, 111, 11N ... indoor unit, 12
1, 12N ... Indoor heat exchanger, 131, 13N ... Indoor fan, 141, 14N ... Indoor expansion valve, 15 ... Gas pipe, 16
... liquid pipe, 171, 17N ... branch pipe, 18 ... outdoor air temperature detector, 19 ... outdoor heat exchanger liquid side temperature detector, 20 ... outdoor heat exchanger gas side temperature detector, 21 ... refrigerant discharge temperature detector , 22 ... Refrigerant suction pressure detector, 23 ... Refrigerant discharge pressure detector, 24 ... Compressor power consumption detector, 25 ... Outdoor fan power consumption detector, 26 ... Inverter compressor drive frequency controller, 27 ... Outdoor fan blower Capacity operator, 28 ... Outdoor expansion valve opening operator, 29 ... Four-way valve operator, 301, 30N
... Indoor air temperature detector 311, 31N ... Blow-off air temperature detector, 321, 32N ... Indoor heat exchanger gas side temperature detector, 331, 33N ... Indoor heat exchanger liquid side temperature detector,
38 ... Refrigerant type setting device, 39 ... Computing device, 40 ... Control device.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Yoshida 390 Muramatsu, Shimizu City, Shizuoka Prefecture, Hitachi, Ltd., Air Conditioning Systems Division (72) Inventor Kenichi Nakamura 390, Muramatsu, Shimizu City, Shizuoka Hitachi, Ltd., Air Conditioning Systems Business (56) References JP-A-8-152203 (JP, A) JP-A-7-190535 (JP, A) JP-A-8-136068 (JP, A) Actual development Sho-63-188448 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F25B 47/02 F25B 47/02 570 F24F 11/02 101 F25B 5/00 309

Claims (2)

(57) [Claims] 1. A refrigeration cycle in which an outdoor unit having a compressor, a four-way valve, an outdoor heat exchanger and an outdoor expansion valve, and an indoor unit having an indoor expansion valve and an indoor heat exchanger are connected by piping. In the air conditioner, detection means for detecting the heat exchanger temperature, setting means for setting the type of refrigerant enclosed in the refrigeration cycle, and outdoor heat according to the type of refrigerant set by the setting means An air conditioner comprising: a unit that calculates a determination value of an exchanger temperature; and a unit that starts defrosting based on the determination value. 2. The air conditioner according to claim 1, further comprising setting means for setting an HFC type refrigerant as the type of the refrigerant.