JP4920624B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner called a multi-air conditioner in which a plurality of indoor units are connected to one outdoor unit.

  Conventional multi-air conditioners generally include an expansion valve in a connection path between an indoor unit and a compressor, an outdoor heat exchanger, an outdoor fan, and the like, and the indoor unit includes an indoor heat exchanger, an indoor fan, and the like. . For example, Patent Literature 1 and Patent Literature 2 are raised.

Therefore, the expansion valve connected to the indoor unit in the cooling operation is controlled so that the evaporation of the refrigerant is almost completed near the outlet of the indoor heat exchanger by the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger for each indoor unit. To do.
JP-A-5-31427 JP 2005-69655 A

  However, in the above method, even if the expansion valve of the outdoor unit corresponding to one room is fully opened, if the refrigerant near the outlet of the indoor heat exchanger of the indoor unit of the other room is still dry, Operate the corresponding expansion valve in the opening direction. Here, the “still dry state” means a state in which the refrigerant, which has been decompressed by the expansion valve, becomes a small amount of gas and liquid, evaporates in the indoor heat exchanger, becomes all refrigerant gas, and further becomes superheated gas. .

  If the refrigerant in the vicinity of the outlet of the indoor heat exchanger in the chamber where the expansion valve is not fully opened is still dry, the expansion valve corresponding to the chamber is controlled in the opening direction, and the amount of refrigerant circulation increases. Then, the refrigerant circulation amount flowing to the indoor heat exchanger of the indoor unit of the chamber in which the expansion valve is fully opened further decreases. Therefore, the capacity of the chamber in which the expansion valve is fully open is reduced, and the outlet side of the indoor heat exchanger is dried and air that is not dehumidified is sucked into the blower, so that the blower and the like are dewed.

  An object of the present invention is to provide a multi-air conditioner in which the balance of the capabilities of the rooms is not greatly lost or is not exposed.

  In order to achieve the above object, the present invention includes an expansion valve in a connection path between a plurality of indoor units and compressors, outdoor heat exchangers, outdoor blowers, and the like, each having an indoor heat exchanger, an indoor fan, and the like. In an air conditioner equipped with an outdoor unit and provided with means for detecting the inlet temperature and outlet temperature of the indoor heat exchanger, during cooling operation, a difference between the outlet temperature and the inlet temperature of each indoor unit becomes a target value. The expansion valve is controlled as described above, and when at least one expansion valve is fully opened, control of the expansion valve in the other chamber in the opening direction is prohibited.

  The present invention also includes a plurality of indoor units and compressors including an indoor heat exchanger, an indoor fan, and the like, an outdoor unit including an expansion valve in a connection path between the compressor, the outdoor heat exchanger, the outdoor fan, and the indoor unit, In an air conditioner equipped with a means to detect the inlet and outlet temperatures of the indoor heat exchanger, the expansion valve is controlled so that the difference between the outlet temperature and the inlet temperature of each indoor unit becomes a target value during cooling operation. In addition, when at least one expansion valve is fully opened, the expansion valve in each chamber is controlled so that the difference from the target value in each chamber becomes constant.

  The present invention also includes a plurality of indoor units and compressors including an indoor heat exchanger, an indoor fan, and the like, an outdoor unit including an expansion valve in a connection path between the compressor, the outdoor heat exchanger, the outdoor fan, and the indoor unit, In an air conditioner equipped with a means to detect the inlet and outlet temperatures of the indoor heat exchanger, the expansion valve is controlled so that the difference between the outlet temperature and the inlet temperature of each indoor unit becomes a target value during cooling operation. In addition, when at least one expansion valve is fully opened, the expansion valve of each chamber is controlled so that the difference from the target value of each chamber becomes a value determined by the capacity of each chamber.

  According to the present invention, the expansion valve is controlled so that the difference between the outlet temperature and the inlet temperature of each indoor unit becomes a certain target value. When even one expansion valve is fully opened, the expansion valve of the other chamber is opened. Control the expansion valve of each chamber so that the difference from the target value of each chamber becomes a value determined by the capacity of each chamber, or the difference from the target value of each chamber is Since the expansion valve of each chamber is controlled so as to be constant, the problems of unbalanced capacity and dew condensation due to load fluctuations and pipe length differences in each chamber are solved.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a refrigeration cycle diagram of a multi air conditioner in which two indoor units are connected to one outdoor unit. A compressor 2, an outdoor heat exchanger 3, and an outdoor blower 17 (not shown) are connected to the outdoor unit 1. In addition, a first expansion valve 4 and a second expansion valve 5 are provided on pipes from the refrigerant connection from the first indoor unit 6 and the second indoor unit 7, respectively. The first indoor unit 6 is installed in a room of a plurality of living rooms, and the second indoor unit 7 is installed in another room. The first expansion valve 4 and the second expansion valve 5 are attached to a stepping motor (not shown), and the opening degree is adjusted by the number of steps.

  The first indoor unit 6 and the second indoor unit 7 include a first indoor heat exchanger 8, a second indoor heat exchanger 9, a first indoor blower 22 (not shown), and a second indoor unit, respectively. An indoor blower 23 (not shown) is mounted, and a first inlet thermistor 10 and a second inlet thermistor 11 are provided on the inlet side of the first indoor heat exchanger 8 and the second indoor heat exchanger 9. On the outlet side, a first outlet thermistor 14 and a second outlet thermistor 15 are provided.

  FIG. 2 is an electric circuit diagram, and the outdoor control circuit 16, the outdoor blower 17, and the compressor 2 are connected in parallel to the power source. The outdoor fan relay 18, the compressor relay 19, the first expansion valve 4, and the second expansion valve 5 are controlled by the output of the outdoor control circuit 16.

  The first indoor control circuit 20, the second indoor control circuit 21, the first indoor blower 22, and the second indoor blower 23 are connected to the power supply in parallel. The first indoor fan relay 24 and the second indoor fan relay 25 are controlled by the outputs of the first indoor control circuit 20 and the second indoor control circuit 21, respectively.

  The first inlet thermistor 10 and the second inlet thermistor 11 set the temperatures of the inlets of the first indoor heat exchanger 8 and the second indoor heat exchanger 9 to the first outlet thermistor 14 and the second outlet thermistor 14, respectively. The outlet thermistor 15 inputs the temperatures of the outlets of the first indoor heat exchanger 8 and the second indoor heat exchanger 9 to the first indoor control circuit 20 and the second indoor control circuit 21, respectively. . Further, the first indoor control circuit 20 and the second indoor control circuit 21 are in communication with the outdoor control circuit 16.

  A characteristic operation of the present invention of the multi-air conditioner configured as described above will be described with reference to the flowcharts of FIGS. As shown in FIG. 3, when the cooling operation of the first indoor unit 6 is started (step S1), the first indoor blower relay 24 is closed by the first indoor control circuit 20, and the first indoor blower 22 is turned on. Driven (step S2), the outdoor fan relay 18 is closed by the outdoor control circuit 16, and the outdoor fan 17 is driven (step S3). The output of the outdoor control circuit 16 causes the first expansion valve 4 to have a certain opening P1 (for example, the opening given by the step number “100” of the stepping motor) (step S4), and the second expansion valve 5 The fully closed opening (for example, the opening given by the step number “0” of the stepping motor).

  The compressor relay 19 is closed by the outdoor control circuit 16, the compressor 2 starts operation (step S5), and the discharge gas is sent to the outdoor heat exchanger 3. This refrigerant gas exchanges heat with outdoor air in the outdoor heat exchanger 3 to be condensed and liquefied. This condensate is depressurized by the first expansion valve 4, evaporated by the first indoor heat exchanger 8, and cools and dehumidifies the indoor air blown from the indoor blower 17. The refrigeration cycle in which the evaporated refrigerant gas returns to the compressor 2 is repeated. Since the second expansion valve 5 is fully closed (closed), the refrigerant does not flow through the second indoor heat exchanger 9.

The difference SH ₁ (= T _OUT1 −T _IN1 ) between the temperature T _OUT1 detected by the first outlet thermistor 14 in step S7 and the temperature T _IN1 detected by the first inlet thermistor 10 in step S6 is obtained. If it is equal to or higher than a certain value (target value) T1 (for example, 5 ° C.) (positive determination in step S8), as long as the first expansion valve 4 and the second expansion valve 5 are not fully opened (negative determination in steps S9 and S10). Then, the first expansion valve 4 is controlled to be opened by a predetermined step p0 (for example, one step) (that is, P1 = P1 + p0) (step S11), the process returns to step S4, and the first expansion valve 4 is set to a new opening P1. Set. If either one of the first expansion valve 4 and the second expansion valve 5 is fully open, affirmative determination in steps S9 and S10), the opening degree of the first expansion valve 4 is maintained as it is, and the process returns to step S4.

A difference SH ₁ (= T _OUT1 −T _IN1 ) between the temperature T _OUT1 detected by the first outlet thermistor 14 in step S6 and the temperature T _IN1 detected by the first inlet thermistor 10 in step S7 is obtained. When it is less than a certain fixed value (target value) T1 (for example, 5 ° C.) (negative determination in step S8), the first expansion valve 4 is controlled to be closed by a predetermined step p0 (for example, one step) (that is, P1 = P1−p0). (Step S12), the process returns to Step S4, and the first expansion valve 4 is set to a new opening P1. In this way, the opening degree of the first expansion valve 4 is adjusted so that the refrigerant evaporates almost completely near the outlet of the first indoor heat exchanger 8.

  By the way, since it is a multi air conditioner, as shown in FIG. 4, the cooling operation of the second indoor unit 7 may be further started during the cooling operation of the first indoor unit 6. When the cooling operation of the second indoor unit 7 is started (step S21), the second indoor blower relay 25 is closed by the second indoor control circuit 21 and the second indoor blower 23 is driven (step S22). ). The output of the outdoor control circuit 16 causes the second expansion valve 5 to have a set opening P2 (for example, an opening given by the step number “100” of the stepping motor) (step S23).

  The compressor relay 19 is closed by the outdoor control circuit 16, the compressor 2 continues to operate (step S24), and the discharge gas is sent to the outdoor heat exchanger 3. This refrigerant gas exchanges heat with outdoor air in the outdoor heat exchanger 3 to be condensed and liquefied. The condensate is depressurized by the second expansion valve 5, evaporated by the second indoor heat exchanger 9, and cools and dehumidifies the indoor air blown from the indoor blower 17. The refrigeration cycle in which the evaporated refrigerant gas returns to the compressor 2 is repeated. Since the first indoor unit 6 is also in the cooling operation, the first expansion valve 4 is opened at the opening P1 and the refrigerant flows to the second indoor heat exchanger 9 as well. Become.

A difference SH ₂ (= T _OUT2 −T _IN2 ) between the temperature T _OUT2 detected by the second outlet thermistor 15 in step S26 and the temperature T _IN2 detected by the second inlet thermistor 11 in step S25 is obtained. When it is equal to or higher than a certain value (target value) T2 (for example, 5 ° C.) (positive determination in step S27), unless the second expansion valve 5 and the first expansion valve 4 are fully opened (negative determination in steps S28 and S29). Then, the second expansion valve 5 is controlled to be opened by a predetermined step p0 (for example, one step) (that is, P2 = P2 + p0) (step S30), the process returns to step S23, and the first expansion valve 4 is set to a new opening P2. Set. If either one of the second expansion valve 5 and the first expansion valve 4 is fully open, an affirmative determination in steps S28 and S29), the opening degree of the second expansion valve 5 is maintained as it is, and the process returns to step S23.

A difference SH ₂ (= T _OUT2 −T _IN2 ) between the temperature T _OUT2 detected by the second outlet thermistor 15 in step S26 and the temperature T _IN2 detected by the second inlet thermistor 11 in step S25 is obtained. When it is less than a certain fixed value (target value) T2 (for example, 5 ° C.) (negative determination in step S27), the second expansion valve 5 is controlled to be closed by a predetermined step p0 (for example, one step) (that is, P2 = P2−p0). (Step S31), the process returns to Step S23, and the second expansion valve 5 is set to a new opening P2. In this way, the opening degree of the second expansion valve 5 is adjusted so that the refrigerant evaporates almost completely near the outlet of the second indoor heat exchanger 9.

Normally, when cooling to a set indoor temperature, the outdoor temperature and the indoor temperature are used after the start of operation, and the opening is considered appropriate at that time. However, it is necessary to change the opening degree in accordance with a change in indoor temperature, a change in outdoor temperature, and the operating status of other indoor units. For example, as described above, when the second indoor unit 7 starts operation, the refrigerant circulating in the first indoor heat exchanger 8 of the first indoor unit 6 decreases. Therefore, the refrigerant in the first indoor heat exchanger 8 of the first indoor unit 6 is likely to evaporate before reaching the outlet of the first indoor heat exchanger 8, and SH ₂ is higher than its target value. turn into. Therefore, the opening degree of the first expansion valve 4 is gradually increased to increase the amount of refrigerant flowing into the first indoor heat exchanger 8 of the first indoor unit 6, and the outlet of the first indoor heat exchanger 8. The evaporation is completed in the vicinity, and SH ₂ is brought closer to the target value. In this way, the cooling operation control is performed.

However, if the load on the first indoor unit 6 is large or the first expansion valve 4 is controlled by a long pipe or the like, the target value T1 is not reached even if the opening degree is fully opened (for example, 500 steps). There is a case. Here, if the second expansion valve 5 advances in the opening direction, the amount of refrigerant flowing through the second indoor unit further increases. For this reason, the first indoor heat exchanger 8 of the first indoor unit 6 is increased. The amount of refrigerant flowing inside decreases. Then, since the first indoor heat exchanger 8 is directed further dry direction, SH ₁ becomes a larger value from a target value T1.

  Therefore, when the first expansion valve 4 is fully opened (affirmative determination in steps S9 and S29), control in the opening direction is prohibited by control of the second expansion valve 5. As a result, a larger amount of refrigerant does not flow into the second heat exchanger 9 of the second indoor unit 6, and as a result, the amount of refrigerant circulation in the first indoor unit 6 does not further decrease, The first indoor heat exchanger 8 is further stopped from moving in the drying direction. The same applies when the second expansion valve 5 is first fully opened (affirmative determination in steps S10 and S28).

Next, another embodiment will be described with reference to FIG. In step S9 of FIG. 3 or step S29 of FIG. 4, it is assumed that the first expansion valve 4 is fully opened during the cooling operation of the first indoor unit 6 and the second indoor unit 7 (step S51). ). At this time, the difference SH ₁ between the temperature T _OUT1 detected by the first outlet thermistor 14 of the first indoor unit 6 in step S53 and the temperature T _IN1 detected by the first inlet thermistor 10 in step S52. Is the target value T1 + α, the temperature T _OUT2 detected by the second outlet thermistor 15 of the second indoor unit 7 in step S55 and the temperature T _IN2 detected by the second inlet thermistor 11 in step S54. When the difference SH ₂ is the target value T2 + β, the opening of the second expansion valve 5 is maintained while the first expansion valve 4 is fully opened so that α = β, that is, the difference from the target value is constant. To control. That is, in step S56, if α> β, the second expansion valve 5 is controlled to be closed (step S57). If α <β, the second expansion valve 5 is controlled to be closed (step S58). The opening degree of the second expansion valve 5 is controlled while the first expansion valve 4 is fully opened so that .beta. In addition, about the method of control of the opening degree of the 2nd expansion valve 5, it can carry out using a known method.

  As a result, when the first expansion valve 4 is fully opened (affirmative determination in steps S9 and S29), the first indoor heat exchanger 8 and the second indoor heat exchanger 9 are slightly dry. The refrigerant circulation amounts of the first indoor unit 6 and the second indoor unit 7 are controlled with good balance. When even one expansion valve is fully opened, the expansion valve in each chamber is controlled so that the difference from the target value in each chamber becomes constant. The same applies when the second expansion valve 5 is first fully opened (affirmative determination in steps S10 and S28).

  Still another embodiment will be described with reference to FIG. Steps S61 to S65 are the same as steps S51 to S55 in FIG. In this embodiment, α and β are the difference between the capacities of the first indoor unit 6 and the second indoor unit 7 (for example, the rated capacity of the first indoor unit 6 is 2.0 kW, and the second indoor unit 7 Is a ratio determined by a target value T1 (for example, 5 ° C.) and T2 (for example, 3 ° C.) (that is, α: β = 5: 3), the opening degree of the first expansion valve 4 and the second expansion valve 5 is controlled. That is, if α / β> 5/3 in step S66, the second expansion valve 5 is controlled to be closed (step S67), and if α / β <5/3, the second expansion valve 5 is controlled to be opened. (Step S68), the opening degree of the second expansion valve 5 is controlled with the first expansion valve 4 fully opened so that α: β = 5: 3. In addition, about the method of control of the opening degree of the 2nd expansion valve 5, it can carry out using a known method.

  Generally, when the rated capacity of the indoor unit is small, the refrigerant circulation amount is small. Therefore, the pressure loss when the refrigerant passes through the heat exchanger is smaller when the rated capacity is smaller. Therefore, the target value of the temperature difference between the outlet temperature and the inlet temperature for the refrigerant to be dried to the same degree in the indoor heat exchanger of each indoor unit is different as T1 and T2. Therefore, it is desirable to change the values of α and β according to the rated capacity. Thereby, when the 1st expansion valve 4 will be in a full open state (affirmation determination of step S9, S29), the balance of refrigerant | coolant circulation amount is controlled better. The same applies when the second expansion valve 5 is first fully opened (affirmative determination in steps S10 and S28).

  In the above embodiment, the cooling only cycle has been described. However, the same control can be applied to the cooling / heating cycle equipped with the four-way valve 26 as shown in FIG. 7 during the cooling operation. In the above embodiment, the first inlet thermistor 10, the second inlet thermistor 11, the first outlet thermistor 14, and the second outlet thermistor 15 are provided in the indoor unit. May be provided. Moreover, although said embodiment described the case where there were two indoor units, it is the same also about the multi air conditioner which has two or more indoor units.

  As described above, when the control as described above is performed, the balance between the capabilities of the indoor units is greatly lost, or the evaporation is not completed near the outlet of the indoor unit. An air conditioner that does not have a problem of exposure to the like is provided.

These are the refrigerating-cycle diagrams of an example of the multi air conditioner concerning an embodiment of the invention. These are the said multi air-conditioner electric circuit diagrams. These are the flowcharts for demonstrating an example of an operation | movement at the time of starting the air_conditionaing | cooling operation of a 1st indoor unit with the said multi air conditioner. These are the flowcharts for demonstrating an example of operation | movement at the time of the air_conditionaing | cooling operation of a 2nd indoor unit being started during the air_conditioning | cooling operation of a 1st indoor unit with the said multi air conditioner. These are the flowcharts for demonstrating an example of operation | movement when the 1st expansion valve will be in a full open state during the air_conditionaing | cooling operation of the 1st, 2nd indoor unit by the said multi air conditioner. These are the flowcharts for demonstrating the other example of operation | movement when a 1st expansion valve will be in a full open state during the air_conditionaing | cooling operation of the 1st, 2nd indoor unit by the said multi air conditioner. These are the refrigerating-cycle diagrams of the other example of the multi air-conditioner which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outdoor unit 2 Compressor 3 Outdoor heat exchanger 4 1st expansion valve 5 2nd expansion valve 6 1st indoor unit 7 2nd indoor unit 8 1st indoor heat exchanger 9 2nd indoor heat exchange Unit 10 First inlet thermistor 11 Second inlet thermistor 14 First outlet thermistor 15 Second outlet thermistor 16 Outdoor control circuit 17 Outdoor blower 18 Outdoor blower relay 19 Compressor relay 20 First indoor control Circuit 21 Second indoor control circuit 22 First indoor blower 23 Second indoor blower 24 First indoor blower relay 25 Second indoor blower relay 26 Four-way valve

Claims (3)

  A plurality of indoor units equipped with an indoor heat exchanger, an indoor blower and the like, a compressor, an outdoor heat exchanger, an outdoor unit equipped with an expansion valve in a connection path between the outdoor blower and the indoor unit, In an air conditioner provided with means for detecting the inlet temperature and outlet temperature, during cooling operation, the expansion valve is controlled so that there is a difference between the outlet temperature of each indoor unit and the inlet temperature, and even one of them is controlled. An air conditioner characterized by prohibiting control of an expansion valve in another chamber in the opening direction when the expansion valve is fully opened.   A plurality of indoor units equipped with an indoor heat exchanger, an indoor blower and the like, a compressor, an outdoor heat exchanger, an outdoor unit equipped with an expansion valve in a connection path between the outdoor blower and the indoor unit, In an air conditioner provided with means for detecting the inlet temperature and outlet temperature, during cooling operation, the expansion valve is controlled so that there is a difference between the outlet temperature of each indoor unit and the inlet temperature, and even one of them is controlled. An air conditioner that controls an expansion valve of each chamber so that a difference from a target value of each chamber becomes constant when the expansion valve is fully opened.   A plurality of indoor units equipped with an indoor heat exchanger, an indoor blower and the like, a compressor, an outdoor heat exchanger, an outdoor unit equipped with an expansion valve in a connection path between the outdoor blower and the indoor unit, In an air conditioner provided with means for detecting the inlet temperature and outlet temperature, during cooling operation, the expansion valve is controlled so that there is a difference between the outlet temperature of each indoor unit and the inlet temperature, and even one of them is controlled. An air conditioner that controls an expansion valve in each chamber so that a difference from a target value in each chamber becomes a value determined by the capacity of each chamber when the expansion valve is fully opened.

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