JP5046895B2 - Air conditioner and operation control method thereof - Google Patents

Description

  The present invention relates to a multi-room air conditioner in which a plurality of indoor units are connected to a single outdoor unit, and a refrigerant flow rate distributed to each indoor unit is controlled by an electronic expansion valve of each indoor unit. The present invention relates to an air conditioner that can be operated with a high coefficient of performance (COP) during operation and can save energy, and an operation control method thereof.

  In recent years, demand for a multi-room air conditioner in which a plurality of indoor units are connected to a single outdoor unit has increased due to the advantages of outdoor space saving and small power supply capacity. Conventionally, in this multi-room air conditioner, even if the capacity of the indoor unit being operated during the cooling operation is different, the expansion means provided in the refrigerant pipe of each indoor unit is used to It has been proposed to appropriately control the flow rate of refrigerant supplied to each indoor unit by individually controlling the superheat degree SH of the refrigerant. For example, in the conventional multi-room air conditioners described in Patent Documents 1 and 2, the refrigerant flow rate according to the required capacity is controlled by controlling the degree of superheat SH at a plurality of indoor heat exchanger outlets having different capacity ranks to be constant. I was doing control.

  Conventionally, in order to efficiently use the capacity of the outdoor heat exchanger, a refrigerant circulation heat transfer device that controls the degree of supercooling SC of the refrigerant at the outlet of the outdoor heat exchanger has been proposed. For example, in the conventional refrigerant circulation heat transfer device described in Patent Document 3, the degree of supercooling SC of the refrigerant at the outlet of the outdoor heat exchanger is controlled using the throttle means provided in the bypass pipe.

JP-A-5-79721 JP 2005-16782 A JP 11-182944 A

In this type of multi-room air conditioner, if the conditions such as the temperature condition of the air, the heat load, and the number of operating indoor units are different, the preferred refrigerant charge amount that can be operated with a high COP is different. The refrigerant charge amount in the refrigerant circuit cannot be easily changed.
In the conventional multi-room air conditioner, the refrigerant flow rate of each indoor unit is controlled by controlling the superheat degree SH of the refrigerant at the outlet of the indoor heat exchanger, so that the air temperature conditions, the heat load, and the operation of the indoor unit If the refrigerant charging amount is not appropriate due to conditions such as the number of units, excess refrigerant may be generated. Then, when surplus refrigerant is generated, the surplus refrigerant stays in the high-pressure element device, so that there is a problem that the compression power increases more than necessary and efficient operation cannot be performed.

  Further, in the conventional refrigerant circulation heat transfer device, the throttle means on the indoor unit side is not controlled, and only the supercooling degree SC of the refrigerant at the outdoor heat exchanger outlet is controlled. Since the refrigerant inlet state and outlet state of the throttle means change due to changes in the heat load and the like, there is a problem that the refrigerant flow rate flowing into each indoor unit cannot be adjusted appropriately and efficient operation cannot be performed. there were.

  The present invention has been made to solve the above-mentioned problems, and performs appropriate refrigerant flow rate control and processing of surplus refrigerant staying in the high-pressure side element device, so that the temperature conditions of the air, the indoor unit It is an object of the present invention to obtain an air conditioner and an operation control method thereof that can perform efficient operation in accordance with the number of operating units, heat load, and amount of refrigerant enclosed, and can save energy.

An air conditioner according to the present invention includes a compressor, an outdoor heat exchanger, an outdoor unit having an accumulator, an indoor heat exchanger, and a plurality of indoor units having a first throttle means of the indoor heat exchanger, Control means, one end of the liquid pipe is connected to the outlet of the outdoor heat exchanger, the other end is branched and connected to the inlet of the indoor heat exchanger via the first throttle means, and One end of the gas pipe is connected to the accumulator, the other end is branched and connected to the outlet of the indoor heat exchanger, and the refrigerant is the compressor, the outdoor heat exchanger, the first throttle means, the indoor A refrigerant circuit that circulates in the order of the heat exchanger, the accumulator, and the compressor is configured to perform the cooling operation. The air conditioner further includes a bypass pipe that communicates the liquid pipe and the accumulator, a second throttle means disposed in the bypass pipe, and a refrigerant temperature that detects a refrigerant temperature at the outlet of the indoor heat exchanger. A detecting means, an evaporating temperature detecting means for detecting the evaporating temperature, a refrigerant temperature detecting means for detecting the refrigerant temperature at the outlet of the outdoor heat exchanger, a condensing temperature detecting means for detecting the condensing temperature, and the outdoor heat of the liquid pipe. An internal heat exchanger that exchanges heat between the refrigerant at the outlet of the exchanger and the refrigerant at the outlet of the second throttling means of the bypass pipe. The control means calculates the degree of superheat of the refrigerant based on the difference between the refrigerant condensing temperature and the refrigerant temperature at the outlet of each of the indoor heat exchangers, and based on the degree of superheat, the first throttle means The amount of refrigerant flowing into each of the indoor heat exchangers is adjusted by controlling the opening, and a threshold is set for the degree of refrigerant subcooling at the outlet of the outdoor heat exchanger, and the refrigerant at the outlet of the outdoor heat exchanger is adjusted . A subcooling degree of the refrigerant is calculated based on a difference temperature between the evaporation temperature and the refrigerant temperature, and when the calculated subcooling degree is within a predetermined range, the second throttling means is operated based on the subcooling degree. When the calculated degree of supercooling is outside a predetermined range, the degree of refrigerant is controlled based on the difference between the refrigerant condensing temperature and the refrigerant temperature at the outlet of the internal heat exchanger of the bypass pipe. The degree of superheat is calculated, and the second throttle is calculated based on the calculated degree of superheat. The excess refrigerant by controlling the opening means staying in the outlet of the outdoor heat exchanger via the bypass pipe is configured to return to the accumulator.

  According to the present invention, it is possible to appropriately control the refrigerant flow rate even when the refrigerant charging amount is not appropriate for conditions such as air temperature conditions, the number of indoor units operated, and fluctuations in heat load. Since the operation with the high COP can be maintained by processing the surplus refrigerant, efficient operation can be performed and energy saving can be achieved.

Embodiments of the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
1 is a refrigerant circuit diagram showing an air-conditioning apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, this air conditioner is an air conditioner dedicated to cooling provided with two indoor units for one outdoor unit, and includes a compressor 1 for compressing refrigerant and an outdoor heat exchanger 2. An outdoor unit A having an outdoor fan 2-a and an accumulator 7 for introducing outdoor air into the outdoor heat exchanger 2, and an indoor fan 5-introducing the indoor heat exchanger 5 and the indoor air into the indoor heat exchanger 5. The indoor unit B which has two indoor units which consist of a, and the control means 19 which controls a drive of elemental equipment are provided. In the first embodiment, the indoor unit B has two indoor units. However, the number of indoor units is not limited to two, but has three or more indoor units. May be.

  One end of the compressor discharge side pipe 20 is connected to the refrigerant discharge port of the compressor 1, and the other end is connected to the inlet of the outdoor heat exchanger 2. One end of the liquid pipe 3 is connected to the outlet of the outdoor heat exchanger 2, and the other end is branched and connected to the inlet of each indoor heat exchanger 5. One end of the gas pipe 6 is connected to the upper portion of the accumulator 7, and the other end is branched and connected to the outlet of each indoor heat exchanger 5. One end of the compressor suction side pipe 21 is connected to the refrigerant suction port of the compressor 1, and the other end is connected to the upper portion of the accumulator 7. Further, one end of the bypass pipe 8 is connected to the liquid pipe 3 and the other end is connected to the gas pipe 6. Moreover, the electronic expansion valve 4 as the first throttle means is installed in the liquid pipe 3 after branching to each indoor unit, and the electronic expansion valve 9 as the second throttle means is installed in the bypass pipe 8. .

  A discharge pressure detector 11 for detecting the discharge pressure of the refrigerant is provided in the compressor discharge side pipe 20, and a suction pressure detector 12 for detecting the suction pressure of the refrigerant is provided in the compressor suction side pipe 21. A refrigerant temperature detector 14 is disposed near the outlet of the outdoor heat exchanger 2 in the liquid pipe 3. Refrigerant temperature detectors 15 and 16 are disposed in the vicinity of the entrance / exit of the indoor heat exchanger 5 in the liquid pipe 3 and the gas pipe 6. The refrigerant temperature detectors 14 to 16 can obtain the same effect by measuring the surface temperature of each pipe instead of directly measuring the refrigerant temperature. An indoor temperature detector 17 and an outdoor air temperature detector 18 are provided on the air side of each of the indoor heat exchanger 5 and the outdoor heat exchanger 2 and measure, for example, the suction temperature as a representative temperature on the air side. The discharge pressure detector 11 and the suction pressure detectors 11 and 12 correspond to refrigerant pressure detection means, and the refrigerant temperature detectors 14, 15, and 16 correspond to refrigerant temperature detection means.

  The control means 19 drives the compressor 1 based on detection signals from the discharge pressure detector 11, the suction pressure detector 12, the refrigerant temperature detectors 14 to 16, the indoor temperature detector 17 and the outside air temperature detector 18. The driving of the fan motor of the fan 2-a, the opening degree of the electronic expansion valves 4 and 9, and the driving of the fan motor of the indoor fan 5-a are controlled. In addition, the control means 19 includes a memory 19a in which a function for determining each control value from temperature and pressure measurement results described later is stored.

The operation of the air conditioner configured as described above will be described.
First, the low-temperature and low-pressure refrigerant gas in the accumulator 7 is sucked into the compressor 1 through the compressor suction side pipe 21, is compressed by the compressor 1, and is discharged as high-temperature and high-pressure refrigerant gas. It is introduced into the outdoor heat exchanger 2 through the discharge side pipe 20. The high-temperature and high-pressure refrigerant gas introduced into the outdoor heat exchanger 2 is heat-exchanged with the outdoor air introduced into the outdoor heat exchanger 2 by the outdoor fan 2-a, and while the outdoor air is heated, It becomes a high-pressure refrigerant. Further, the medium-temperature and high-pressure refrigerant flows through the liquid pipe 3 and is decompressed by the electronic expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant, and flows through the liquid pipe 3 and passes through the indoor heat exchanger. 5 is introduced. The low-temperature, low-pressure gas-liquid two-phase refrigerant introduced into the indoor heat exchanger 5 is heat-exchanged with the indoor air introduced into the indoor heat exchanger 5 by the indoor fan 5-a to cool the indoor air. However, it changes to low-temperature and low-pressure refrigerant vapor. The low-temperature and low-pressure refrigerant vapor flows through the gas pipe 6 and is returned to the accumulator 7. The refrigerant returned to the accumulator 7 is separated into gas and liquid, and low-temperature and low-pressure refrigerant gas is sucked into the compressor 1 through the compressor suction side pipe 21.

  Here, when the refrigerant charging amount is larger than the appropriate refrigerant amount, the surplus refrigerant flows from the outdoor heat exchanger 2 through the liquid pipe 3 and the bypass pipe 8 and is decompressed by the electronic expansion valve 9 to be cooled at a low temperature. It becomes a low-pressure gas-liquid two-phase refrigerant, flows through the bypass pipe 8, joins with the refrigerant vapor after cooling through the gas pipe 6, and returns to the accumulator 7.

  Thus, as indicated by solid arrows in FIG. 1, the refrigerant is compressor 1 → compressor discharge side pipe 20 → outdoor heat exchanger 2 → liquid pipe 3 → electronic expansion valve 4 → indoor heat exchanger. 5 → Gas pipe 6 → Accumulator 7 → Compressor suction side pipe 21 → Compressor 1 is circulated in the refrigerant circuit in order and cooling operation is performed, and excess refrigerant is added to the outdoor heat exchanger 2 → liquid pipe 3 → bypass. Pipe 8 → electronic expansion valve 9 → gas pipe 6 → accumulator 7 flows.

Next, the behavior of the cycle and the COP when the surplus refrigerant is treated using the bypass pipe 8 and when the surplus refrigerant is not treated will be described with reference to FIGS. FIG. 2 shows a change in the high-pressure side pressure P _H [MPa] with respect to the refrigerant charge amount M [kg] in the refrigerant circuit, and FIG. 3 shows the excess of the outdoor heat exchanger outlet with respect to the refrigerant charge amount M [kg] in the refrigerant circuit. FIG. 4 shows the change in the refrigerant temperature T _ref [° C.] at the outlet of the outdoor heat exchanger with respect to the refrigerant charge amount M [kg] in the refrigerant circuit, and FIG. 6 shows a change in COP [−] with respect to the refrigerant charge amount M [kg], FIG. 6 shows a Ph diagram when the surplus refrigerant process is not controlled, and FIG. 7 performs the surplus refrigerant process control. The Ph diagram in this case is shown. In each figure, point A is when the refrigerant charging amount M is too small, point B is when the refrigerant charging amount M is appropriate, and points C and D are when the refrigerant charging amount M is excessive.

When the surplus refrigerant is not processed without using the bypass circuit, as shown in FIGS. 2 to 4, the high pressure side pressure P _H and the degree of supercooling SC increase as the refrigerant charging amount increases, and the outdoor heat exchange is performed. It can be seen that the refrigerant temperature _{Tref at the} outlet of the vessel decreases. Then, as shown in FIG. 6, the refrigerant filling amount M of the increases from point A to point B, although the input work of a compressor for compressing refrigerant to a high pressure side pressure P _H is increased, the outdoor heat exchanger outlet The specific enthalpy h _ref [kJ / kg] is also greatly reduced. Therefore, with respect to the percentage of increase of the input work of a compressor for compressing refrigerant to a high pressure side pressure P _H, the ratio of the amount of increase in the cooling capacity due to the specific enthalpy h _ref of the outdoor heat exchanger outlet is significantly reduced From this, it can be seen that COP increases. On the other hand, as shown in FIG. 6, C-point refrigerant charge M from point B, increasing the D point, although the input work of a compressor for compressing refrigerant to a high pressure side pressure P _H is increased, the outdoor heat exchanger The specific enthalpy h _{ref at the} outlet of the vessel will not decrease much. Therefore, with respect to the percentage of increase of the input work of a compressor for compressing refrigerant to a high pressure side pressure P _H, the ratio of the amount of increase in the cooling capacity due to the specific enthalpy h _ref of the outdoor heat exchanger outlet is reduced smaller Therefore, it can be seen that COP decreases. Therefore, as shown in FIG. 5, the COP increases with an increase in the refrigerant charging amount M, takes a maximum value at the point B, and then decreases.

On the other hand, when treated with excess refrigerant by using a bypass circuit, since compressed by the compressor, will return a portion of refrigerant cooled in the outdoor heat exchanger directly to the accumulator, the high side pressure P _H, The degree of supercooling SC at the outlet of the outdoor heat exchanger and the refrigerant temperature T _{ref at the} outlet of the outdoor heat exchanger become substantially constant when the refrigerant charging amount M is at or above the B point. Therefore, the refrigerant filling amount M of the high-pressure side pressure P _H is substantially constant at least point B, as shown in FIG. 7, C, cycle D is approximately equal to the cycle of the B, it does not process the excess refrigerant Compared to the case, the input work of the compressor can be reduced. Further, by reducing the SH at the compressor inlet, the specific entropy s [kJ / (kg · K)] of the suction refrigerant is reduced, and the input work of the compressor can be reduced. Due to these effects, as shown in FIG. 5, even if the refrigerant charging amount M is larger than the appropriate amount (point B), the COP is almost the same as the case of the appropriate refrigerant amount.

As described above, when the refrigerant charging amount M is larger than the appropriate amount, the excess refrigerant is processed to thereby increase the high-pressure side pressure P _H , the degree of supercooling SC at the outdoor heat exchanger outlet, and the outdoor heat exchanger. The refrigerant temperature T _{ref at the} outlet becomes constant. From this, the constant values of the high-pressure side pressure P _H , the degree of supercooling SC at the outlet of the outdoor heat exchanger, and the refrigerant temperature T _{ref at} the outlet of the outdoor heat exchanger are set to control target values P _H ^* , SC ^* , T _ref ^By setting as ^* and controlling the electronic expansion valve 9 according to any index, the air conditioner can be operated with a high COP.

For example, when taking a high-pressure side pressure P _H in the control indicator, if the current high-pressure side pressure P _H is larger than the control target value P _H ^* of the high-pressure side pressure to open the opening of the electronic expansion valve 9 In the case where it is small, the opening degree of the electronic expansion valve 9 may be controlled to be closed. Similarly, when the supercooling degree SC at the outlet of the outdoor heat exchanger is taken as a control index, if the current supercooling degree SC is larger than the control target value SC ^* of the supercooling degree, the electronic expansion valve 9 The opening degree may be opened, and if the opening degree is small, the opening degree of the electronic expansion valve 9 may be closed. When the refrigerant temperature T _ref at the outlet of the outdoor heat exchanger is taken as a control index, if the current refrigerant temperature T _ref is larger than the refrigerant temperature control target value T _ref ^{*, the} electronic expansion valve 9 is opened. The degree may be closed, and if small, the opening of the electronic expansion valve 9 may be controlled to open.

If the refrigerant charging amount M is less than the appropriate charging amount, the electronic expansion valve 9 should be fully closed in order to send more refrigerant to the indoor unit. For example, the high pressure side pressure P when taking the _H to the control indicator, the refrigerant charge M is too small, since the high-pressure side pressure P _H does not reach the control target value P _H ^* of the high-pressure side pressure, closed further be fully closed It is possible to achieve full closure by the control method described above.

  Next, the change in COP with respect to the opening degree of the electronic expansion valve 4 in each case when the heat load is large and small, and the change in COP with respect to the degree of superheat at the outlet of the indoor heat exchanger will be described with reference to FIGS. To do. FIG. 8 shows the change in COP [−] with respect to the opening degree Cv [−] of the throttle means of the indoor unit, and FIG. 9 shows the change in COP [−] with respect to the degree of superheat SH [° C.] at the outlet of the indoor heat exchanger. Yes.

  From FIG. 8, it can be seen that the state of the entrance / exit of the electronic expansion valve 4 changes depending on the thermal load, so that the opening Cv of the electronic expansion valve 4 suitable for obtaining a high COP changes depending on the magnitude of the thermal load. Further, FIG. 9 shows that the degree of superheat SH at the outlet of the indoor heat exchanger suitable for obtaining a high COP becomes substantially constant regardless of the magnitude of the heat load. Therefore, if the degree of opening Cv of the electronic expansion valve 4 is controlled so that the degree of superheat SH at the outlet of the indoor heat exchanger becomes constant regardless of the heat load, the operation can be performed with a high COP. The same applies when the temperature of the air changes.

  As described above, the superheat degree SH of the refrigerant at the outlet of each indoor heat exchanger 5 is calculated, and the throttle means (electronic expansion valve 4) of each indoor heat exchanger 5 is used based on the calculated superheat degree SH. By controlling the flow rate of the refrigerant flowing into each indoor unit using the throttle means (electronic expansion valve 9) of the bypass pipe 8 so as to return the excess refrigerant staying at the outlet of the outdoor unit to the accumulator 7, The air conditioner can be operated with a high COP even if the operating conditions fluctuate, such as fluctuations in the air temperature condition and thermal load, or the refrigerant charging amount is not appropriate and surplus refrigerant is generated.

Next, a method for adjusting the flow rate of the refrigerant flowing into the heat exchanger 5 by controlling the opening degree (C _ν4 ) of the electronic expansion valve 4 based on the superheat degree SH of the refrigerant at the outlet of the indoor heat exchanger 5. This will be described with reference to FIG. FIG. 10 is a flowchart for explaining the control of the degree of supercooling SC of the refrigerant at the outlet of the outdoor heat exchanger 2 by the electronic expansion valve 9. In the drawing, steps 1 to 5 are designated S1 to S5 for convenience. Here, the control means 19 sets the opening degree (C _ν4 ) of the electronic expansion valve 4 to the current value of the superheat degree SH of the refrigerant at the outlet of the indoor heat exchanger 5 and the target at a constant interval, for example, 1 minute. Proportional control is performed based on the difference in values.

First, in step 1, an initial value of the opening degree (C _ν4 ) of the electronic expansion valve 4 that is a control value of the control device is output. Next, in step 2, the temperature difference between the temperature detected by the refrigerant temperature detector 16 and the temperature detected by the refrigerant temperature detector 15, or the evaporation temperature based on the pressure detected by the suction pressure detector 12 and the temperature detected by the refrigerant temperature detector 15. Based on the difference in temperature, the superheat degree SH of the refrigerant at the outlet of the current indoor heat exchanger 5 is calculated. Here, the control means 19 calculates the evaporation temperature based on the detected pressure of the suction pressure detector 12, and the control means 19 constitutes the evaporation temperature detection means together with the suction pressure detector 12. Further, since the refrigerant evaporation temperature calculated based on the detected pressure of the suction pressure detector 12 matches the refrigerant temperature at the inlet of the indoor heat exchanger 5, the refrigerant temperature detector 16 is also used as the evaporation temperature detecting means. Function. Next, carried out in step 3 by the equation (1), if the difference from the calculated degree of superheat target value of SH (the target degree of superheat SH ^*) is within the allowable range epsilon ₁ set confirmation.
| SH-SH ^* | <ε ₁ Formula (1)

When the difference between the current superheat degree SH and the target superheat degree SH ^* is within the set allowable range, the electronic expansion valve 4 is operated while maintaining the opening degree (C _ν4 ). If the difference is not within the set allowable range, the process proceeds to step 4.

In step 4, the adjustment amount ΔC _ν4 of the opening degree of the electronic expansion valve 4 is calculated based on the difference between the current superheat degree SH and the target superheat degree SH ^*, and the _{process proceeds} to step 5. Here, the adjustment amount ΔC _ν4 of the opening degree of the electronic expansion valve 4 is calculated based on the equation (2).
ΔC _ν4 = f ₁ (SH-SH ^* ) (2)
The function f ₁ (SH-SH ^* ) may be simply set to a ₁ × (SH-SH ^* ) by setting an appropriate constant a ₁ for the system. Further, if a ₁ is changed based on SH time-series data instead of setting a ₁ as a constant, convergence can be accelerated.

Next, in step 5, the opening degree of the electronic expansion valve 4 is corrected and output based on the calculated adjustment amount ΔC _ν4 of the opening degree of the electronic expansion valve 4, and the process returns to step 2. Thereby, when the present superheat degree SH is larger than the target superheat degree SH ^* , the opening degree of the electronic expansion valve 4 is opened based on the difference (SH-SH ^* ) between the current value and the target value. On the other hand, when the current superheat degree SH is smaller than the target superheat degree SH ^* , the opening degree of the electronic expansion valve 4 is closed based on the difference between the current value and the target value (SH-SH ^* ). Then, the control from step 2 to step 5 is continued until this control index falls within the allowable range.

  In the above description, the refrigerant pressure is detected by the suction pressure detector 12 provided in the compressor suction side pipe 21, but the refrigerant pressure is limited to the refrigerant pressure in the compressor suction side pipe 21. The refrigerant pressure in any one of the pipes from the electronic expansion valve 4 to the compressor 1 suction port may be used.

Next, as a method of returning surplus refrigerant to the accumulator 7 via the bypass pipe 8, the opening degree (C _ν9 ) of the electronic expansion valve 9 is determined based on the degree of refrigerant _subcooling SC at the outlet of the outdoor heat exchanger 2. The case of controlling will be described. FIG. 11 is a flowchart for explaining the control of the degree of refrigerant supercooling SC at the outlet of the outdoor heat exchanger 2 by the electronic expansion valve 9. In the drawing, steps 11 to 15 are designated S11 to S15 for convenience. Here, the control means 19 sets the opening degree (C _ν9 ) of the electronic expansion valve 9 to the current value of the refrigerant _subcooling SC at the outlet of the outdoor heat exchanger 2 at a constant interval, for example, 1 minute interval. Proportional control is performed based on the difference in target values.

First, in step 11, an initial value of the opening degree (C _ν9 ) of the electronic expansion valve 9 that is an initial value of the control device is output. Next, in step 12, based on the temperature difference between the condensation temperature based on the pressure detected by the discharge pressure detector 11 and the temperature detected by the refrigerant temperature detector 14, the refrigerant excess at the outlet of the current outdoor heat exchanger 2 is detected. The degree of cooling SC is calculated. Here, the control means 19 calculates the condensation temperature based on the detected pressure of the discharge pressure detector 11, and the control means 19 constitutes the condensation temperature detection means together with the discharge pressure detector 11. Next, we performed in step 13, by the equation (3), if the difference from the calculated subcooling degree target value of SC (target degree of supercooling SC ^*) is within the allowable range ε within ₂ set the confirmation.
| SC-SC ^* | <ε ₂ Formula (3)

When the difference between the current supercooling degree SC and the target supercooling degree SC ^* is within the set allowable range, the electronic expansion valve 9 is operated while maintaining the opening degree (C _ν9 ). If the difference is not within the set allowable range, the process proceeds to step 14.

In step 14, the adjustment amount ΔC _ν9 of the opening degree of the electronic expansion valve 9 is calculated based on the difference between the current supercooling degree SC and the target supercooling degree SC ^*, and the _{process proceeds} to step 15. Here, the adjustment amount ΔC _ν9 of the opening degree of the electronic expansion valve 9 is calculated based on the equation (4).
ΔC _ν9 = f ₂ (SC−SC ^* ) (4)
The function f ₂ (SC-SC ^* ) may be simply set to a ₂ × (SC-SC ^* ) by setting an appropriate constant a ₂ for the system. In addition, instead of setting a ₂ as a constant, if a ₂ is changed based on SC time-series data, convergence can be accelerated.

  In the above description, the refrigerant pressure is detected by the discharge pressure detector 11 provided in the compressor discharge side pipe 20. However, the refrigerant pressure is limited to the refrigerant pressure in the compressor discharge side pipe 20. The refrigerant pressure in any one of the pipes from the compressor 1 discharge port to the electronic expansion valve 4 may be used.

Next, in step 15, the opening degree of the electronic expansion valve 9 is corrected and output based on the calculated adjustment amount ΔC _ν9 of the electronic expansion valve 9, and the process returns to step 12. Thereby, when the current supercooling degree SC is larger than the target supercooling degree SC ^* , the opening degree of the electronic expansion valve 9 is opened based on the difference between the current value and the target value (SC-SC ^* ). On the other hand, when the current supercooling degree SC is smaller than the target supercooling degree SC ^* , the opening degree of the electronic expansion valve 9 is closed based on the difference between the current value and the target value (SC-SC ^* ). Then, the control from step 12 to step 15 is continued until the control index falls within the allowable range.

  Here, in step 12, the refrigerant at the outlet of the current outdoor heat exchanger 2 is based on the temperature difference between the condensation temperature based on the pressure detected by the discharge pressure detector 11 and the temperature detected by the refrigerant temperature detector 14. However, the indoor heat exchanger-side refrigerant temperature detector is installed near the center of the indoor heat exchanger where the refrigerant in the indoor heat exchanger 5 becomes a gas-liquid two-phase flow. The refrigerant subcooling degree SC at the outlet of the outdoor heat exchanger 2 is calculated based on the temperature difference between the temperature detected by the indoor heat exchanger side refrigerant temperature detector and the temperature detected by the refrigerant temperature detector 14. May be.

Next, an example of the control of the rotational speed (f) of the compressor 1 and the rotational speed (F ₀ ) of the outdoor fan 2-a will be described. Figure 12 is a flowchart illustrating control of the low side pressure _{P L} and the high side pressure _{P H} by the compressor 1 and the outdoor fan 2-a of the outdoor unit, in the figure for convenience, the steps 21 to 25 as S21~S25 Yes. Here, the control means 19 sets the rotation speed (f) of the compressor 1 and the rotation speed (F ₀ ) of the outdoor fan 2-a to a low pressure side pressure P _L and a high pressure side at regular intervals, for example, 1 minute intervals. performing based on proportional control the difference between the current value and the target value of the pressure P _H.

First, in step 21, initial values of the rotation speed (f) of the compressor 1 and the rotation speed (F ₀ ) of the outdoor fan 2-a, which are initial values of the control device, are output. Next, in step 22, the discharge pressure detector 11 and the discharge pressure detector 12, measures the current on the low-pressure side pressure P _L, and the high-pressure side pressure P _H. Next, at step 23, by the equation (5) (6), measured low side pressure _{P L,} and the target value of the high-pressure side pressure _{P H} (target low-pressure side pressure _P ^{L *,} and the target high-pressure side pressure _P ^{H *} ) Is confirmed to be within the set allowable ranges ε ₃ and ε ₄ .
| P _L −P _L ^* | <ε ₃ (5)
| P _H −P _H ^* | <ε ₄ Formula (6)

If the difference between the current low pressure side pressure P _L and the high pressure side pressure P _{H from} the target low pressure side pressure P _L ^* and the target high pressure side pressure P _H ^* is within the set allowable range, the compressor The engine is operated while maintaining the rotation speed (f) of 1 and the rotation speed (F ₀ ) of the outdoor fan 2-a. If the difference is not within the set allowable range, the process proceeds to step 24.

In step 24, the amount of adjustment of the rotational speed of the compressor 1 based on the difference between the current low pressure side pressure P _L and the high pressure side pressure P _{H from} the target low pressure side pressure P _L ^* and the target high pressure side pressure P _H ^*. Δf and the adjustment amount ΔF ₀ of the rotational speed of the outdoor fan 2-a are calculated, and the routine proceeds to step 25. Here, the rotation speed adjustment amount Δf of the compressor 1 and the rotation speed adjustment amount ΔF ₀ of the outdoor fan 2-a are calculated based on the equations (7) and (8).
Δf = f ₃ (P _L −P _L ^* ) (7)
ΔF _o = f ₄ (P _H −P _H ^* ) (8)
Note that the functions f ₃ (P _L -P _L ^* ) and f ₄ (P _H -P _H ^* ) are simply set as appropriate constants a ₃ and a ₄ for the system, and a ₃ × (P _L − P _L ^* ), a ₄ × (P _H -P _H ^* ) may be set. In addition, instead of setting a ₃ and a ₄ as constants, convergence can be accelerated by changing a ₃ and a ₄ based on time-series data of P _L and P _H.

Then, in step 25, the rotational speed and the rotation of the outdoor fan 2-a of the compressor 1 based on the rotation speed of the adjustment amount [Delta] F ₀ of the adjustment amount Δf and outdoor fan 2-a of the calculated compressor 1 rpm The number is corrected and output, and the process returns to step 22. Thereby, when the current low pressure side pressure P _L is larger than the target low pressure side pressure P _L ^* , the rotation speed of the compressor 1 is determined based on the difference between the current value and the target value (P _L −P _L ^* ). Enlarge. On the other hand, when the current low-pressure side pressure P _L is smaller than the target low-pressure side pressure P _L ^* , the rotational speed of the compressor 1 is reduced based on the difference between the current value and the target value (P _L −P _L ^* ). To do. Further, if the current high-pressure side pressure P _H is larger than the target high-pressure side pressure P _H ^* is based on the rotational speed of the outdoor fan 2-a to the difference between the current value and the target value (P H _-P H ^_*) Make it bigger. On the other hand, when the current high-pressure side pressure P _H is smaller than the target high-pressure side pressure P _H ^* is based on the rotational speed of the outdoor fan 2-a to the difference between the current value and the target value (P H _-P H ^_*) And make it smaller. Then, the control from step 22 to step 25 is continued until this control index falls within the allowable range.

Note that the high and low pressure target values can be operated with a high COP if the control target value is changed in accordance with the outside air temperature, the room temperature, and the heat load. In the first embodiment, the electronic expansion valve 4 is used for SH control at the outlet of the indoor heat exchanger, the electronic expansion valve 9 is used for SC control at the outlet of the outdoor heat exchanger, the compressor 1, and the outdoor fan 2- a is used for controlling the high-pressure side pressure and the low-pressure side pressure. However, when the control value of the outdoor fan 2-a is set to a constant value and the electronic expansion valve 9 controls the high-pressure side pressure, the control is simplified. it can. Further, in the first embodiment, a control device such as the compressor 1 and the outdoor fan 2-a, the high side pressure P _H, was set to control a one-to-one control indicators such as the low-pressure side pressure P _L However, the convergence can be accelerated by combining the control index and the control device matrix and performing the control. As a method for controlling the room temperature, the compressor may be stopped if the room temperature of all the rooms in the cooling operation reaches a preset temperature. However, if the target low pressure side pressure P _L ^* is changed to be higher when the room temperature approaches the preset temperature, and the cooling capacity is controlled to match the required capacity (heat load), the high pressure side pressure Since the pressure difference between P _H and the low-pressure side pressure P _L becomes smaller and the compressor can be operated with a reduced input, the operation can be continued with a high COP.

Also, this time, the control target value SC of the supercooling degree SC and the high side pressure P _H of the refrigerant at the outlet of the outdoor heat exchanger 2 ^*, was controlled by setting the P _H ^* to a constant value, the outdoor heat exchanger in view of the performance of the vessel 2, when the thermal load is large is changed to increase the SC ^* or P _H ^*, when the thermal load is small if changed to be small SC ^* or P _H ^* The operation can be performed in a state where the COP is higher. Furthermore, since the outdoor heat exchanger 2 is usually large and the air volume is designed to be large, the refrigerant temperature T _{ref at} the outlet of the outdoor heat exchanger 2 is a temperature substantially close to the outdoor air temperature. Therefore, if the control target value T _ref ^* of the refrigerant temperature is set to a value that is 1 to 10 ° C. higher than the outside air temperature, for example, about 5 ° C., regardless of the heat load or the like, , conveniently than when the high side pressure P _H as a control index, COP can perform operation in a state of high.

  Further, the rotational speed of the indoor fan 5-a may be set to full speed or set by a remote controller. Furthermore, if the operation is performed based on a control index such as a sensible heat ratio SHF (Sensible Heat Factor), it is possible to perform an operation in which indoor comfort is ensured.

Embodiment 2. FIG.
FIG. 13 is a refrigerant circuit diagram showing an air-conditioning apparatus according to Embodiment 2 of the present invention.
In FIG. 13, the four-way switching valve 10 supplies the high-temperature and high-pressure refrigerant discharged from the compressor 1 to the outdoor heat exchanger 2 or the indoor heat exchanger 5, and from the indoor heat exchanger or the outdoor heat exchanger. The discharged low-temperature and low-pressure refrigerant is disposed so as to be returned to the accumulator 7.
Other configurations are the same as those in the first embodiment. That is, the air conditioner according to the first embodiment operates as an air conditioner dedicated to cooling, but the air conditioner according to the second embodiment switches the refrigerant flow path by the four-way switching valve 10, It operates as a cooling / heating switching type air conditioner.

A heating operation of the air conditioner according to the second embodiment will be described.
First, the low-temperature and low-pressure refrigerant gas in the accumulator 7 is sucked into the compressor 1 through the compressor suction-side pipe 21, compressed by the compressor 1, and discharged as high-temperature and high-pressure refrigerant gas. The high-temperature and high-pressure refrigerant gas is introduced into the indoor heat exchanger 5 through the four-way switching valve 10 and the gas pipe 6. The high-temperature and high-pressure refrigerant gas introduced into the indoor heat exchanger 5 is heat-exchanged with the indoor air introduced into the indoor heat exchanger 5 by the indoor fan 5-a, and the temperature is lowered while heating the indoor air. . Then, the refrigerant discharged from the indoor heat exchanger 5 is throttled and depressurized by the electronic expansion valve 4, and changes to a low-temperature and low-pressure gas-liquid two-phase state. The refrigerant in the gas-liquid two-phase state is introduced into the outdoor heat exchanger 2 through the liquid pipe 3, and heat is exchanged with the outdoor air introduced into the outdoor heat exchanger 2 by the outdoor fan 2-a. Is cooled to change to low-temperature and low-pressure refrigerant gas. Thereafter, the refrigerant gas passes through the four-way switching valve 10 and is returned to the accumulator 7. The refrigerant gas returned to the accumulator 7 is gas-liquid separated, and the low-temperature and low-pressure refrigerant gas is sucked into the compressor 1 via the compressor suction side pipe 21.

  Thus, in the heating operation, as indicated by the dotted arrow in FIG. 13, the refrigerant is the compressor 1, the four-way switching valve 10, the gas pipe 6, the indoor heat exchanger 5, the electronic expansion valve 4, and the liquid pipe. It circulates in the refrigerant circuit in the order of 3 → outdoor heat exchanger 2 → four-way switching valve 10 → accumulator 7 → compressor suction side pipe 21 → compressor 1.

Next, the cooling operation of the air-conditioning apparatus according to Embodiment 2 will be described.
First, the low-temperature and low-pressure refrigerant gas in the accumulator 7 is sucked into the compressor 1 through the compressor suction-side pipe 21, compressed by the compressor 1, and discharged as high-temperature and high-pressure refrigerant gas. The high-temperature and high-pressure refrigerant gas is introduced into the outdoor heat exchanger 2 through the four-way switching valve 10 and the compressor discharge side pipe 20. The high-temperature and high-pressure refrigerant gas introduced into the outdoor heat exchanger 2 is heat-exchanged with the outdoor air introduced into the outdoor heat exchanger 2 by the outdoor fan 2-a, and the medium-temperature and high-pressure is heated while heating the outdoor air. It becomes a refrigerant. Further, the medium-temperature and high-pressure refrigerant flows through the liquid pipe 3 and is decompressed by the electronic expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant, and flows through the liquid pipe 3 and passes through the indoor heat exchanger. 5 is introduced. The low-temperature, low-pressure gas-liquid two-phase refrigerant introduced into the indoor heat exchanger 5 is heat-exchanged with the indoor air introduced into the indoor heat exchanger 5 by the indoor fan 5-a to cool the indoor air. However, it changes to low-temperature and low-pressure refrigerant vapor. The low-temperature and low-pressure refrigerant vapor flows through the gas pipe 6 and is returned to the accumulator 7. The refrigerant returned to the accumulator 7 is separated into gas and liquid, and low-temperature and low-pressure refrigerant gas is sucked into the compressor 1 through the compressor suction side pipe 21.

  Thus, in the cooling operation, as indicated by the solid arrow in FIG. 13, the refrigerant is compressor 1 → compressor discharge side pipe 20 → outdoor heat exchanger 2 → liquid pipe 3 → electronic expansion valve 4 → It circulates in the refrigerant circuit in the order of the indoor heat exchanger 5 → the gas pipe 6 → the accumulator 7 → the compressor suction side pipe 21 → the compressor 1.

  Also in the second embodiment, during the cooling operation, similarly to the first embodiment, the superheat degree SH of the refrigerant at the outlet of the indoor heat exchanger 5 is calculated, and the electronic expansion is performed based on the calculated superheat degree SH. The opening degree of the valve 4 is controlled to control the flow rate of the refrigerant flowing into the indoor heat exchanger 5, and the opening degree of the electronic expansion valve 9 is controlled so that the excess refrigerant staying at the outlet of the outdoor heat exchanger 2 is removed. By returning to the accumulator 7 via the bypass pipe 8, the distribution of the refrigerant flow according to the capacity of the indoor unit can be efficiently performed even when the air temperature condition, heat load condition, etc. fluctuate during cooling operation. In addition to being able to do so, it is possible to optimize the high-pressure side pressure by treating the surplus refrigerant, prevent the input of extra compression power, and operate with a high COP.

Embodiment 3 FIG.
FIG. 14 is a refrigerant circuit diagram showing an air-conditioning apparatus according to Embodiment 3 of the present invention.
In FIG. 14, an internal heat exchanger 30 is disposed so that heat can be exchanged between the liquid pipe 3 and the accumulator side of the electronic expansion valve 9 of the bypass pipe 8.
Other configurations are the same as those in the second embodiment.

  In the third embodiment, heat exchange is performed between the refrigerant flowing through the liquid pipe 3 and the refrigerant flowing through the bypass pipe 8 using the internal heat exchanger 30 in order to effectively use the cooling energy of the surplus refrigerant. If the refrigerant in the liquid pipe 3 is cooled, the COP is improved.

In the cooling operation of the air conditioner, when the refrigerant charging amount is excessive, the high pressure side pressure P _H , the degree of supercooling SC at the outlet of the outdoor heat exchanger 2, and the refrigerant temperature T _ref at the outlet of the outdoor heat exchanger 2 are set. If the surplus refrigerant is processed as a control index in the same manner as in the first embodiment, operation can be performed with a high COP. However, when the refrigerant charging amount is too small, the electronic expansion valve 9 is fully closed by the above method, and the internal heat exchanger 30 cannot be used. Therefore, thresholds are set for the high pressure side pressure P _H , the degree of supercooling SC at the outlet of the outdoor heat exchanger 2, and the refrigerant temperature T _ref at the outlet of the outdoor heat exchanger 2, and P _H , SC, T _ref are, for example, P _H ^* , SC ^*, T _ref ^* if it becomes lower than, it is determined that the amount of refrigerant charging is excessively small, the switching control method of the electronic expansion valve 9, the refrigerant at the outlet of the internal heat exchanger 30 of the bypass pipe 8 If the opening degree of the electronic expansion valve 9 is controlled on the basis of the degree of superheat of the refrigerant, when the refrigerant filling amount is excessive, the excess refrigerant is processed using the bypass pipe and the refrigerant filling amount is too small. In addition, the temperature of the refrigerant flowing into the indoor unit can be lowered by the internal heat exchanger 30, and the operation can be performed in a state where the COP is high with respect to each refrigerant filling amount regardless of the refrigerant filling amount. it can.

Incidentally, and degree of supercooling SC of the outdoor heat exchanger outlet refrigerant temperature T _ref, a method of controlling a high side pressure P _H and the like, fluorocarbon refrigerant, a hydrocarbon-based refrigerant, ammonia, refrigerant on the high pressure side condenser, This is effective for an air conditioner using a vapor compression refrigeration cycle in which the refrigerant evaporates on the low pressure side.

In addition, when a refrigerant whose high pressure side exceeds the critical pressure is used under the use conditions such as carbon dioxide, the high pressure side pressure P _H can be controlled by the above control method when the high pressure side pressure PH is lower than the critical pressure. _{When H} becomes higher than the critical pressure, the condensation temperature cannot be defined. Therefore, the refrigerant temperature at the outlet of the outdoor heat exchanger 2 or the refrigerant temperature at the outlet of the outdoor heat exchanger 2 is used instead of the degree of supercooling SC. By controlling the difference in the outside air temperature, it is possible to perform the operation with a high COP. Furthermore, as the definition of the condensation temperature above the critical pressure, the temperature having the largest specific heat at that pressure (pseudocritical temperature), the specific enthalpy of the critical pressure and the temperature obtained from the pressure are assumed to be the pseudo condensation temperature T _c ′. and, even when the pseudo supercooling degree SC of the _{'(= T c' -T d} ) was controlled at a constant value, suitably the temperature difference between the refrigerant and the indoor air when the indoor temperature T _i has fluctuated And can be operated with a high COP.

It is a refrigerant circuit diagram which shows the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the refrigerant | coolant amount and the high voltage | pressure side pressure in the refrigerating cycle of the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the refrigerant | coolant amount and the supercooling degree in the refrigerating cycle of the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the refrigerant | coolant amount in the refrigerating cycle of the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention, and the refrigerant | coolant temperature of an outdoor heat exchanger exit. It is a figure which shows the relationship between the refrigerant | coolant amount and COP in the refrigerating cycle of the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a pressure-specific enthalpy diagram when not using the bypass circuit in the refrigerating cycle of the refrigerant circuit of the air harmony device concerning Embodiment 1 of this invention. It is a pressure-specific enthalpy diagram at the time of using the bypass circuit in the refrigerating cycle of the refrigerant circuit of the air conditioning apparatus concerning Embodiment 1 of this invention. It is a figure which shows the relationship between the opening degree of the electronic expansion valve 4, and COP in the refrigerating cycle of the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the superheat degree and COP in the refrigerating cycle of the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a flowchart of operation control when the superheat degree of the refrigerant | coolant of the indoor heat exchanger exit in the air conditioning apparatus which concerns on Embodiment 1 of this invention is made into a control parameter | index. It is a flowchart of operation control when the supercooling degree of the refrigerant | coolant of the outdoor heat exchanger exit in the air conditioning apparatus which concerns on Embodiment 1 of this invention is made into a control parameter | index. It is a flowchart of operation control when the rotation speed of the compressor and outdoor fan in the air conditioning apparatus which concerns on Embodiment 1 of this invention is made into a control parameter | index. It is a refrigerant circuit figure which shows the air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a refrigerant circuit figure which shows the air conditioning apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Outdoor heat exchanger, 3 Liquid piping, 4 Electronic expansion valve (1st throttle means), 5 Indoor heat exchanger, 6 Gas piping, 7 Accumulator, 8 Bypass piping, 9 Electronic expansion valve (No. 2 throttle means), 11 discharge pressure detector (refrigerant pressure detection means, condensation temperature detection means), 12 suction pressure detector (refrigerant pressure detection means, evaporation temperature detection means), 14, 15 refrigerant temperature detector (refrigerant temperature detection) Means), 16 refrigerant temperature detector (refrigerant temperature detection means, evaporation temperature detection means), 18 outside air temperature detector, 19 control means, 20 compressor discharge side piping, 21 compressor suction side piping, 30 internal heat exchanger.

Claims (8)

An outdoor unit having a compressor, an outdoor heat exchanger, and an accumulator;
A plurality of indoor units having an indoor heat exchanger and a first throttle means of the indoor heat exchanger;
Control means,
One end of the liquid pipe is connected to the outlet of the outdoor heat exchanger, the other end is branched and connected to the inlet of the indoor heat exchanger via the first throttle means, and one end of the gas pipe is connected to the accumulator. The other end is branched and connected to the outlet of the indoor heat exchanger, and the refrigerant is the compressor, the outdoor heat exchanger, the first throttle means, the indoor heat exchanger, the accumulator, In an air conditioner that performs a cooling operation by configuring a refrigerant circuit that circulates in an annular order in the order of the compressors,
A bypass pipe communicating the liquid pipe and the accumulator;
A second throttle means disposed in the bypass pipe;
Refrigerant temperature detection means for detecting the refrigerant temperature at the outlet of the indoor heat exchanger and evaporation temperature detection means for detecting the evaporation temperature;
Refrigerant temperature detection means for detecting the refrigerant temperature at the outlet of the outdoor heat exchanger and condensation temperature detection means for detecting the condensation temperature;
An internal heat exchanger that exchanges heat between the refrigerant at the outlet of the outdoor heat exchanger of the liquid pipe and the refrigerant at the outlet of the second throttling means of the bypass pipe,
The control means is
The degree of superheat of the refrigerant is calculated based on the difference between the refrigerant evaporation temperature and the refrigerant temperature at the outlet of each of the indoor heat exchangers, and the opening degree of the first throttle means is controlled based on the degree of superheat. While adjusting the flow rate of refrigerant flowing into each indoor heat exchanger,
A threshold is set for the degree of refrigerant subcooling at the outlet of the outdoor heat exchanger, and the degree of refrigerant subcooling is calculated based on the difference between the refrigerant condensing temperature and the refrigerant temperature at the outlet of the outdoor heat exchanger. When the calculated degree of supercooling is within a predetermined range, the opening degree of the second throttle means is controlled based on the degree of supercooling, and when the calculated degree of supercooling is outside the predetermined range. The degree of superheat of the refrigerant is calculated based on the difference between the refrigerant evaporation temperature and the refrigerant temperature at the outlet of the internal heat exchanger of the bypass pipe, and the second throttle means is opened based on the calculated degree of superheat. The air conditioner is configured to return the excess refrigerant remaining at the outlet of the outdoor heat exchanger to the accumulator through the bypass pipe by controlling the degree. An outdoor unit having a compressor, an outdoor heat exchanger, and an accumulator;
A plurality of indoor units having an indoor heat exchanger and a first throttle means of the indoor heat exchanger;
Control means,
One end of the liquid pipe is connected to the outlet of the outdoor heat exchanger, the other end is branched and connected to the inlet of the indoor heat exchanger via the first throttle means, and one end of the gas pipe is connected to the accumulator. The other end is branched and connected to the outlet of the indoor heat exchanger, and the refrigerant is the compressor, the outdoor heat exchanger, the first throttle means, the indoor heat exchanger, the accumulator, In an air conditioner that performs a cooling operation by configuring a refrigerant circuit that circulates in an annular order in the order of the compressors,
A bypass pipe communicating the liquid pipe and the accumulator;
A second throttle means disposed in the bypass pipe;
Refrigerant temperature detection means for detecting the refrigerant temperature at the outlet of the indoor heat exchanger and evaporation temperature detection means for detecting the evaporation temperature;
Refrigerant temperature detection means for detecting the refrigerant temperature at the outlet of the outdoor heat exchanger ;
An internal heat exchanger that exchanges heat between the refrigerant at the outlet of the outdoor heat exchanger of the liquid pipe and the refrigerant at the outlet of the second throttling means of the bypass pipe ,
The control means is
The degree of superheat of the refrigerant is calculated based on the difference between the refrigerant evaporation temperature and the refrigerant temperature at the outlet of each of the indoor heat exchangers, and the opening degree of the first throttle means is controlled based on the degree of superheat. While adjusting the flow rate of refrigerant flowing into each indoor heat exchanger,
A threshold is set for the refrigerant temperature at the outlet of the outdoor heat exchanger, and when the refrigerant temperature at the outlet of the outdoor heat exchanger is within a predetermined range, the opening degree of the second throttle means is controlled based on the refrigerant temperature. If the refrigerant temperature at the outlet of the outdoor heat exchanger is outside the predetermined range, the refrigerant is overheated based on the difference between the refrigerant evaporation temperature and the refrigerant temperature at the outlet of the internal heat exchanger in the bypass pipe. And the excess refrigerant staying at the outlet of the outdoor heat exchanger is returned to the accumulator through the bypass pipe by controlling the opening degree of the second throttle means based on the calculated degree of superheat. It is comprised in the air conditioning apparatus characterized by the above-mentioned. An outdoor unit having a compressor, an outdoor heat exchanger, and an accumulator;
A plurality of indoor units having an indoor heat exchanger and a first throttle means of the indoor heat exchanger;
Control means,
One end of the liquid pipe is connected to the outlet of the outdoor heat exchanger, the other end is branched and connected to the inlet of the indoor heat exchanger via the first throttle means, and one end of the gas pipe is connected to the accumulator. The other end is branched and connected to the outlet of the indoor heat exchanger, and the refrigerant is the compressor, the outdoor heat exchanger, the first throttle means, the indoor heat exchanger, the accumulator, In an air conditioner that performs a cooling operation by configuring a refrigerant circuit that circulates in an annular order in the order of the compressors,
A bypass pipe communicating the liquid pipe and the accumulator;
A second throttle means disposed in the bypass pipe;
Refrigerant temperature detection means for detecting the refrigerant temperature at the outlet of the indoor heat exchanger and evaporation temperature detection means for detecting the evaporation temperature;
Refrigerant pressure detection means for detecting the pressure of the high-pressure side refrigerant in the pipe from the outlet of the compressor to the first throttle means;
An internal heat exchanger that exchanges heat between the refrigerant at the outlet of the outdoor heat exchanger of the liquid pipe and the refrigerant at the outlet of the second throttling means of the bypass pipe ;
The control means is
The degree of superheat of the refrigerant is calculated based on the difference between the refrigerant evaporation temperature and the refrigerant temperature at the outlet of each of the indoor heat exchangers, and the opening degree of the first throttle means is controlled based on the degree of superheat. While adjusting the flow rate of refrigerant flowing into each indoor heat exchanger,
A threshold value is provided for the pressure of the high-pressure side refrigerant, and when the pressure of the high-pressure side refrigerant is within a predetermined range, the opening degree of the second throttle means is controlled based on the pressure of the high-pressure side refrigerant, When the pressure of the refrigerant is outside the predetermined range, the degree of superheat of the refrigerant is calculated based on the temperature difference between the refrigerant evaporation temperature and the refrigerant temperature at the outlet of the internal heat exchanger of the bypass pipe. Based on the degree of superheat, the opening degree of the second throttle means is controlled to return the excess refrigerant staying at the outlet of the outdoor heat exchanger to the accumulator through the bypass pipe. Air conditioner to do. An outdoor unit having a compressor, an outdoor heat exchanger, and an accumulator;
An indoor heat exchanger, and a plurality of indoor units having a first throttle means of the indoor heat exchanger,
One end of the liquid pipe is connected to the outlet of the outdoor heat exchanger, the other end is branched and connected to the inlet of the indoor heat exchanger via the first throttle means, and one end of the gas pipe is connected to the accumulator. The other end is branched and connected to the outlet of the indoor heat exchanger, and the refrigerant is the compressor, the outdoor heat exchanger, the first throttle means, the indoor heat exchanger, the accumulator, A refrigerant circuit that circulates in an annular order in the order of the compressor is configured, and further, a bypass pipe is arranged to communicate the liquid pipe and the accumulator, a second throttle means is arranged in the bypass pipe, and An air conditioner that performs cooling operation by disposing an internal heat exchanger that exchanges heat between the refrigerant at the outlet of the outdoor heat exchanger in the liquid pipe and the refrigerant at the outlet of the second throttle means in the bypass pipe. In the operation control method
The refrigerant evaporating temperature and the refrigerant temperature at the outlet of each of the indoor heat exchangers are measured, and the degree of superheating of the refrigerant is calculated based on the difference between the measured refrigerant evaporating temperature and the refrigerant temperature. And adjusting the flow rate of the refrigerant flowing into each of the indoor heat exchangers by controlling the opening of the first throttle means based on the
A threshold is set for the degree of subcooling of the refrigerant at the outlet of the outdoor heat exchanger, the refrigerant condensation temperature and refrigerant temperature at the outlet of the outdoor heat exchanger are measured, and the measured refrigerant condensation temperature and refrigerant temperature are Based on the differential temperature, the degree of supercooling of the refrigerant is calculated, and when the calculated degree of supercooling is within a predetermined range, the opening degree of the second throttle means is controlled based on the degree of supercooling and calculated. If the degree of supercooling is outside a predetermined range, the refrigerant evaporating temperature and the refrigerant temperature at the outlet of the internal heat exchanger of the bypass pipe are measured, and the measured refrigerant evaporating temperature and refrigerant temperature are measured. The degree of superheat of the refrigerant is calculated based on the difference in temperature, and the degree of opening of the second throttle means is controlled based on the calculated degree of superheat, so that the excess refrigerant staying at the outlet of the outdoor heat exchanger is bypassed by the bypass. Operation of an air conditioner characterized by returning to the accumulator via a pipe Your way. When the pressure of the high-pressure side refrigerant in the pipe from the compressor outlet to the first throttle means is equal to or higher than the critical pressure, the refrigerant temperature at the outlet of the outdoor heat exchanger or the refrigerant at the outlet of the outdoor heat exchanger When the opening of the second throttle means is controlled based on the difference between the temperature and the outside air temperature, and the pressure of the high-pressure side refrigerant is lower than the critical pressure , the condensation temperature of the refrigerant at the outlet of the outdoor heat exchanger And the refrigerant temperature are calculated, the degree of subcooling of the refrigerant is calculated based on the difference between the measured refrigerant condensing temperature and the refrigerant temperature, and the second throttle means is calculated based on the calculated degree of subcooling. The operation control method for an air conditioner according to claim 4 , wherein the opening is controlled. When the pressure of the high-pressure side refrigerant in the pipe from the outlet of the compressor to the first throttle means is equal to or higher than the critical pressure, the condensation temperature equal to or higher than the critical pressure is defined as the temperature having the highest specific heat at the pressure, or The specific enthalpy of the critical pressure and the temperature obtained from the pressure are defined as a pseudo condensing temperature, and the temperature is determined based on the difference between the defined pseudo condensing temperature and the refrigerant temperature at the outlet of the outdoor heat exchanger. 5. The operation control method for an air conditioner according to claim 4, wherein the degree of cooling is calculated . An outdoor unit having a compressor, an outdoor heat exchanger, and an accumulator;
An indoor heat exchanger, and a plurality of indoor units having a first throttle means of the indoor heat exchanger,
One end of the liquid pipe is connected to the outlet of the outdoor heat exchanger, the other end is branched and connected to the inlet of the indoor heat exchanger via the first throttle means, and one end of the gas pipe is connected to the accumulator. The other end is branched and connected to the outlet of the indoor heat exchanger, and the refrigerant is the compressor, the outdoor heat exchanger, the first throttle means, the indoor heat exchanger, the accumulator, A refrigerant circuit that circulates in an annular order in the order of the compressor is configured, and further, a bypass pipe is arranged to communicate the liquid pipe and the accumulator, and a second throttle means is arranged in the bypass pipe, Refrigerant temperature detection means for detecting the refrigerant temperature at the outlet of the outdoor heat exchanger is disposed , and the refrigerant at the outlet of the outdoor heat exchanger in the liquid pipe and the refrigerant at the outlet of the second throttle means in the bypass pipe Heat exchange between Operation control method of an air conditioner which performs cooling operation by disposing the heat exchanger,
The refrigerant evaporating temperature and the refrigerant temperature at the outlet of each of the indoor heat exchangers are measured, the degree of superheating of the refrigerant is calculated based on the difference between the measured evaporating temperature and the refrigerant temperature, and based on the degree of superheating. While adjusting the flow rate of the refrigerant flowing into each of the indoor heat exchangers by controlling the opening of the first throttle means,
A threshold value is set for the refrigerant temperature at the outlet of the outdoor heat exchanger, the refrigerant temperature at the outlet of the outdoor heat exchanger is measured, and when the measured refrigerant temperature is within a predetermined range, the refrigerant temperature is based on the refrigerant temperature. The opening degree of the second throttle means is controlled, and when the measured refrigerant temperature is outside a predetermined range, the refrigerant evaporation temperature and the refrigerant temperature at the outlet of the internal heat exchanger of the bypass pipe are measured. The degree of superheat is calculated based on the difference between the measured evaporation temperature and the refrigerant temperature, and the opening of the second throttle means is controlled based on the calculated degree of superheat , and the outlet of the outdoor heat exchanger The surplus refrigerant | coolant which accumulates in is returned to the said accumulator via the said bypass piping, The operation control method of the air conditioning apparatus characterized by the above-mentioned. An outdoor unit having a compressor, an outdoor heat exchanger, and an accumulator;
An indoor heat exchanger, and a plurality of indoor units having a first throttle means of the indoor heat exchanger,
One end of the liquid pipe is connected to the outlet of the outdoor heat exchanger, the other end is branched and connected to the inlet of the indoor heat exchanger via the first throttle means, and one end of the gas pipe is connected to the accumulator. The other end is branched and connected to the outlet of the indoor heat exchanger, and the refrigerant is the compressor, the outdoor heat exchanger, the first throttle means, the indoor heat exchanger, the accumulator, A refrigerant circuit that circulates in an annular order in the order of the compressor is configured, and further, a bypass pipe is arranged to communicate the liquid pipe and the accumulator, and a second throttle means is arranged in the bypass pipe, An air conditioner that performs cooling operation by disposing an internal heat exchanger that exchanges heat between the refrigerant at the outlet of the outdoor heat exchanger in the liquid pipe and the refrigerant at the outlet of the second throttle means in the bypass pipe. In the operation control method
The refrigerant evaporating temperature and the refrigerant temperature at the outlet of each of the indoor heat exchangers are measured, the degree of superheating of the refrigerant is calculated based on the difference between the measured evaporating temperature and the refrigerant temperature, and based on the degree of superheating. While adjusting the flow rate of the refrigerant flowing into each of the indoor heat exchangers by controlling the opening of the first throttle means,
A threshold value is set for the pressure of the high-pressure side refrigerant, the pressure of the high-pressure side refrigerant is measured, and when the measured pressure of the high-pressure side refrigerant is within a predetermined range, the second pressure is measured based on the pressure of the high-pressure side refrigerant. 2 The opening degree of the throttle means is controlled, and when the pressure of the high-pressure side refrigerant is outside a predetermined range, the refrigerant evaporating temperature and refrigerant temperature at the outlet of the internal heat exchanger of the bypass pipe are measured and measured. The degree of superheat of the refrigerant is calculated based on the difference between the evaporated temperature and the refrigerant temperature, and the opening degree of the second throttle means is controlled based on the calculated degree of superheat to the outlet of the outdoor heat exchanger. An operation control method for an air conditioner, wherein the excess refrigerant that remains is returned to the accumulator through the bypass pipe.

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