JP4815281B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner having a refrigeration cycle, and more particularly to a technique capable of improving efficiency and accelerating the stability of a refrigeration cycle at startup.

In an air conditioner having an indoor heat exchanger and an outdoor heat exchanger and performing a refrigeration cycle, the outdoor heat exchanger may be frosted during heating operation, for example, under conditions where the outdoor air temperature is relatively low. When the frost is formed, the performance of the heat exchanger decreases, so the performance of the air conditioner decreases. Therefore, liquid back is prevented by a method of performing a defrosting operation using high-temperature gas refrigerant discharged from the compressor, or by heating the refrigerant introduced into the compressor using refrigerant heating means such as a heater. A method for performing a defrosting operation is known (for example, see Patent Document 1).
JP-A-3-105183

  The air conditioner using the heater described above has the following problems. That is, the heater is used only for the defrosting operation, and cannot perform other functions, such as improving the efficiency of the refrigeration cycle.

  Then, this invention aims at providing the air conditioner which can perform not only a defrost operation but a heating capability improvement and stable operation by using a refrigerant | coolant heating means.

  In order to solve the problems and achieve the object, the air conditioner of the present invention is configured as follows.

Refrigeration cycle configured by sequentially connecting a compressor, a four-way valve, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger, the evaporation temperature of the outdoor heat exchanger during heating operation, and the outlet of the outdoor heat exchanger Detecting means for detecting the degree of superheat, which is a temperature difference between the suction refrigerant temperature of the suction pipe connecting the compressor and the compressor, and the expansion so that the degree of superheat detected by the detecting means becomes a predetermined control target value. A control means for controlling the opening degree of the apparatus, and a refrigerant heating means provided in the suction pipe, wherein the control means has a degree of superheat at the time of heating by the refrigerant heating means at the time of heating operation as compared with that at the time of non-heating. The control target value is changed so as to increase .

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the air conditioner which can perform not only a defrost operation but a heating capability improvement and stable operation by using a refrigerant | coolant heating means.

  FIG. 1 is a configuration diagram illustrating an air conditioner 10 according to a first embodiment of the present invention, and FIG. 2 is a Ph diagram of the air conditioner 10.

  The air conditioner 10 includes a compressor 11, a discharge pipe 12 connected to the discharge port of the compressor 11, a four-way valve 13 connected to the discharge pipe 12, and an indoor heat exchanger connected to the four-way valve 13. 14, an electronic expansion valve 15 connected to the indoor heat exchanger 14, an outdoor heat exchanger 16 connected to the electronic expansion valve 15, and a suction pipe connected to the outdoor heat exchanger 16 via a four-way valve 13. 17 and an accumulator 19 connected to the suction pipe 17 in order, and has a heater (refrigerant heating means) 18 provided on the inlet of the accumulator 19 on the suction pipe 17, and the accumulator 19 It is connected to the mouth.

  The air conditioner 10 is configured to be able to reverse the direction of refrigerant flow by switching the four-way valve 13.

  A discharge temperature sensor 20 that measures a discharge temperature TD from the compressor 11 is provided at the discharge port of the compressor 11.

  An evaporation temperature sensor 21 that measures the inlet evaporation temperature TE of the outdoor heat exchanger 16 is provided between the electronic expansion valve 15 and the outdoor heat exchanger 16 and at the inlet of the outdoor heat exchanger 16.

  A suction temperature sensor 22 that measures the suction temperature TS to the compressor 11 is provided between the heater 18 and the accumulator 19 on the suction port side of the compressor 11.

  The air conditioner 10 is provided with a controller 30 capable of receiving temperature information from the discharge temperature sensor 20, the evaporation temperature sensor 21, and the suction temperature sensor 22.

  The control unit 30 receives the discharge temperature TD information from the discharge temperature sensor 20, the evaporation temperature TE information from the evaporation temperature sensor 21 and the suction temperature TS information from the suction temperature sensor 22, and based on the temperature information. The opening degree of the electronic expansion valve 15 can be controlled.

  The air conditioner 10 configured as described above is operated as follows. That is, during the heating operation, the suction temperature TS information from the suction temperature sensor 22 and the evaporation temperature TE information from the evaporation temperature sensor 21 are transmitted to the control unit 30, and the superheat degree SH that is the difference between the suction temperature TS and the evaporation temperature TE is transmitted. The opening degree of the electronic expansion valve 15 is controlled by the control unit 30 so that the value (SH = TS−TE) becomes constant.

  During normal heating operation, the SH value is set to a superheat setting value SH1 = TS1-TE (for example, about 5 ° C.) in order to sufficiently obtain the function of the outdoor heat exchanger 16, and the electronic expansion valve 15 is controlled by the control unit 30. The air conditioner 10 is operated while controlling (see FIG. 2).

  During the heating capacity improving operation, the heater 18 is operated, and the superheat setting value is changed to SH2 = TS2-TE> SH1. Thereby, the control part 30 controls the opening degree of the electronic expansion valve 15 so that the evaporation pressure does not become too high. Moreover, the function of the outdoor heat exchanger 16 can be sufficiently obtained, and the heating capacity is improved (see FIG. 2).

  If the superheat setting value SH1 is maintained while the heater 18 is operated, the refrigerant is heated and the opening of the electronic expansion valve 15 is increased. As the opening of the electronic expansion valve 15 increases, the evaporation pressure increases and the evaporation temperature also increases. For this reason, the temperature difference between the temperature of the refrigerant and the temperature of the outside air is reduced, and the efficiency of the outdoor exchanger 16 is deteriorated.

  During the start-up operation, the heater 18 is operated, and the operation is performed at the same superheat setting value SH1 = TS1-TE (for example, 5 ° C.) as in the normal heating operation. By this operation, there is no deterioration in reliability due to the liquid back, and a sufficient amount of refrigerant circulation is obtained, so that the stability of the refrigeration cycle at the time of startup is accelerated (see FIG. 2).

  Unless the superheat setting value SH1 is set, the liquid back operation (SH3 = TS3-TE ≦ 0) tends to occur until the heat balance of the outdoor heat exchanger 16 is stabilized. Therefore, the control unit 30 makes the opening degree of the electronic expansion valve 15 narrow to avoid the liquid back operation. However, if the opening degree of the electronic expansion valve 15 is reduced, the refrigerant circulation amount cannot be obtained, and it takes time to reach a stable state.

  According to the air conditioner 10 according to the present embodiment, the heater 18 is used, the superheat degree setting values SH1 and SH2 are switched depending on the operating state, and the electronic expansion valve 15 is opened based on the superheat degree setting values SH1 and SH2. By adjusting the degree, it becomes possible to improve the heating capacity and perform stable operation.

  In the air conditioner 10 described above, the heater 18 may be capable of capacity control. That is, when a heater capable of capacity control is used, when the heating capacity is small, the SH set value is set small and the control unit 30 controls the electronic expansion valve 15. Similarly, the air conditioner 10 uses a controllable heater, and when the heating capacity is large, the SH set value is set large and the control unit 30 controls the electronic expansion valve 15. Thereby, heating capability can be improved without impairing the function of the outdoor heat exchanger 16.

  Moreover, it is good also as a structure which can control SH setting value according to the operating frequency of the compressor 11. FIG. When the control unit 30 controls the electronic expansion valve 15, it sets the SH set value according to the operating frequency of the compressor 11 and controls the electronic expansion valve 15. Depending on the operating frequency of the compressor 11, the refrigerant circulation amount changes, and the temperature rise value by the heater 18 changes. Therefore, when the operating frequency of the compressor 11 is increased, the SH set value is decreased. When the operating frequency of the compressor 11 decreases, the SH set value is increased. By setting the SH value, the outdoor heat exchanger 16 can improve the heating capacity without impairing the function.

  FIG. 3 is a block diagram showing an air conditioner 40 according to the second embodiment of the present invention. 3 that are the same as those in FIG. 1 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The air conditioner 40 includes a power supply unit 31 such as a commercial power supply, a circuit unit 32 connected to the power supply unit 31 and including an inverter, a control circuit, a charging circuit, and the like, and a storage battery 33 connected to the circuit unit 32. ing.

  The circuit unit 32 is connected to the compressor 11, the electronic expansion valve 15, and the heater 18. The power supply to the heater 18 is mainly supplied from the storage battery 33 to the heater 18 via the circuit unit 32. The indoor heat exchanger 14 is provided with an indoor heat exchanger temperature sensor 23.

  In the air conditioner 40 configured as described above, when the input current to the air conditioner 40 is small, such as when the operation of the compressor 11 is stopped, the battery 33 is charged with current. When the air conditioner 40 is normally operated, the current from the power supply unit 31 is operated via the circuit unit 32 for the operation of the compressor 11 and the control of the electronic expansion valve 15. On the other hand, the heater 18 is operated using the storage battery 33.

  When the cooling operation is started, the heater 18 is operated, the temperature of the indoor heat exchanger 14 is measured by the indoor heat exchanger temperature sensor 23 of the indoor heat exchanger 14, and is controlled by the circuit unit 32 as in the heating operation described above. To do.

  Thus, the current charged in the storage battery 33 when the compressor 11 is stopped can be used as the power source of the heater 18. Therefore, when a current is obtained from the power supply unit 31 of the air conditioner 40 as the power source of the heater 18, the power to be input to the heater 18 cannot be input to the compressor 11, and the power that can be used by the compressor 11 is reduced. Can be prevented. For this reason, the electric power supplied to the compressor 11 can be utilized to the maximum by obtaining the operating current of the heater 18 from the storage battery 33. By utilizing the power supplied to the compressor 11 to the maximum extent, the air conditioner 40 can be operated to exhibit high heating capacity.

  Further, as in the heating operation described above, it is possible to speed up the start of the cooling operation by controlling the electronic expansion valve 15 during the cooling operation based on the temperature information measured by the indoor heat exchanger temperature sensor 23. Become.

  According to the air conditioner 40 according to the present embodiment, the highly efficient and stable operation is performed in the same manner as the air conditioner 10 described above, and the power supplied to the compressor 11 is maximized. Can demonstrate high heating ability.

  The present invention is not limited to the embodiments described above. For example, in the above-described example, only the heater (refrigerant heating means) 18 is specified. However, for example, a positive temperature coefficient thermistor (for example, a PTC heater) may be used for the heater 18. By using the positive temperature coefficient thermistor, excessive heating by the heater can be suppressed by the self-temperature controllability of the positive temperature coefficient thermistor, and a safe air conditioner can be provided.

  The heater 18 can also be applied by using electromagnetic induction heating (for example, IH heater). By using electromagnetic induction heating as the refrigerant heating means, it is possible not to conduct heat from the outside of the suction pipe 17 but to directly heat it from the suction pipe 17, so that the refrigerant can be efficiently overheated. When electromagnetic induction heating is used, electromagnetic induction heating is possible even if the suction pipe 17 is made of copper, but by forming the suction pipe 17 with iron or the like, or by providing an iron member inside the suction pipe 17, More effective heating is possible. Of course, various modifications can be made without departing from the scope of the present invention.

The block diagram which shows the air conditioner which concerns on the 1st Embodiment of this invention. Ph diagram of the air conditioner. The block diagram which shows the air conditioner which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 40 ... Air conditioner, 11 ... Compressor, 12 ... Discharge piping, 13 ... Four-way valve, 14 ... Indoor heat exchanger, 15 ... Electronic expansion valve, 16 ... Outdoor heat exchanger, 17 ... Suction piping, 18 ... Heater, 19 ... Accumulator, 20 ... Discharge temperature sensor, 21 ... Evaporation temperature sensor, 22 ... Suction temperature sensor, 30 ... Control part.

Claims (4)

A refrigeration cycle configured by sequentially connecting a compressor, a four-way valve, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger;
Detecting means for detecting the degree of superheat, which is a temperature difference between the evaporation temperature of the outdoor heat exchanger and the suction refrigerant temperature of the suction pipe connecting the outlet of the outdoor heat exchanger and the compressor during heating operation;
Control means for controlling the opening degree of the expansion device so that the degree of superheat detected by the detection means becomes a predetermined control target value;
A refrigerant heating means provided in the suction pipe,
The air conditioner characterized in that the control means changes the control target value so that the degree of superheat is larger when heating by the refrigerant heating means during heating operation than when not heating .   2. The air conditioner according to claim 1, wherein the refrigerant heating means can change a heating capacity, and the control target value of the degree of superheat varies according to the heating capacity.   The air conditioner according to claim 1 or 2, wherein the compressor is driven by an inverter, and a control target value of the superheat degree is made different according to an operating frequency of the compressor.   The air conditioner according to claim 1, 2, or 3, wherein the refrigerant heating means is supplied with electric power by a storage battery.

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