JP4104218B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner, and more particularly to an air conditioner that favorably controls the valve opening degree of a flow rate adjusting valve that adjusts the flow rate of a refrigerant flowing to an indoor heat exchanger in an indoor unit.
[0002]
[Prior art]
An air conditioner, particularly a multi-type air conditioner, includes an outdoor unit including a compressor and an indoor heat exchanger, and a flow rate adjusting valve (indoor expansion) that adjusts the flow rate of refrigerant flowing into the indoor heat exchanger and the indoor heat exchanger. And a control device for controlling the outdoor unit and the indoor unit, and cooling or heating is performed by each of the plurality of indoor units.
[0003]
In particular, the control device compares the inlet / outlet refrigerant temperature difference, which is the difference between the inlet-side refrigerant temperature and the outlet-side refrigerant temperature in the indoor heat exchanger, with the target inlet / outlet refrigerant temperature difference, and when the former is larger than the latter, Controls to increase the degree of superheat of the refrigerant by increasing the valve opening of the heat exchanger and increasing the cooling / heating capacity of the indoor heat exchanger, and by decreasing the valve opening of the flow control valve when the former is smaller than the latter is doing.
[0004]
Here, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference is fixed and uniformly set for a plurality of indoor units.
[0005]
[Problems to be solved by the invention]
For example, in the case of a non-azeotropic refrigerant mixture such as R407C, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference is set wider than in the case of a single refrigerant or azeotropic refrigerant such as R22. The valve opening is reduced, the degree of superheat of the refrigerant is increased, and the liquid back to the compressor is prevented. However, if the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference is set wide, the amount of refrigerant flowing to each indoor unit decreases, and sufficient cooling / heating capacity by the indoor heat exchanger cannot be obtained. In particular, in a multi-type air conditioner, the amount of refrigerant flowing to the indoor heat exchanger in the indoor unit is insufficient due to poor refrigerant distribution, etc., resulting in an indoor unit that cannot obtain a sufficient cool air feeling. There is a fear.
[0006]
Further, when a priority is set for the indoor unit, the upper limit of the target inlet / outlet refrigerant temperature difference in the indoor heat exchanger is determined by the priority of the indoor unit and the degree of refrigerant load (air conditioning load) in each indoor unit. Although the value is fluctuated, the lower limit value of the target inlet / outlet refrigerant temperature difference is uniform without being fluctuated. Therefore, in this case, there is a possibility that sufficient cool wind feeling cannot be obtained in the indoor unit with the highest priority, particularly during cooling operation.
[0007]
The subject of this invention is made | formed in view of the above-mentioned situation, and provides the air conditioning apparatus which can perform the operation | movement which exhibits the air-conditioning capability by an indoor heat exchanger, and superheat degree control operation with sufficient balance. There is.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is an outdoor unit including a compressor and an outdoor heat exchanger, an indoor unit including an indoor heat exchanger and a flow rate adjusting valve for adjusting a flow rate of refrigerant flowing to the indoor heat exchanger, and An outdoor unit and a control device that controls the indoor unit, and the control device determines an inlet / outlet refrigerant temperature difference that is a difference between an inlet side refrigerant temperature and an outlet side refrigerant temperature in the indoor heat exchanger as a target inlet / outlet refrigerant. In the air conditioner that controls the valve opening degree of the flow rate adjustment valve as compared with the temperature difference, a plurality of the indoor units are installed with priority, and the control device is configured to control the air blown from the indoor heat exchanger. The lower limit value control range of the target inlet / outlet refrigerant temperature difference is changed based on the outlet differential temperature that is the temperature difference between the target outlet temperature and the target outlet temperature . Identical compared to lower priority Set narrowed to output difference temperature, it is characterized in that to increase the valve opening degree of the flow control valve of the indoor unit.
[0017]
The invention described in claim 1 has the following action.
[0018]
The control device changes the control range of the lower limit value in the target inlet / outlet refrigerant temperature difference of the indoor heat exchanger based on the priority order set in the indoor unit and the blowout differential temperature of the indoor heat exchanger in the indoor unit. An indoor unit with a higher priority is set to have a lower control range for the lower limit value of the target inlet / outlet refrigerant temperature difference in the indoor heat exchanger of the indoor unit than for an indoor unit with a lower priority than the same outlet differential temperature. Thus, if the valve opening degree of the flow control valve of the indoor unit is increased, the indoor unit with higher priority can increase the cooling / heating capacity.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a circuit diagram showing an embodiment of an air conditioner according to the present invention.
[0021]
As shown in FIG. 1, the air conditioner 10 includes an outdoor unit 11, a plurality of indoor units 12A, 12B,... And a control device 13, and includes an outdoor refrigerant pipe 14 and the indoor units 12A, 12B of the outdoor unit 11. Are connected to each other to form a refrigerant circuit through which the non-azeotropic refrigerant mixture flows.
[0022]
The outdoor unit 11 is installed outdoors, and a compressor 16 is disposed in the outdoor refrigerant pipe 14. An accumulator 17 is connected to the suction side of the compressor 16, and a four-way valve 18 is connected to the discharge side via the outdoor refrigerant pipe 14. The outdoor heat exchanger 19 and the electric expansion valve 24 are connected to the four-way valve 18 via the outdoor refrigerant pipe 14. An outdoor fan 20 that blows air toward the outdoor heat exchanger 19 is disposed adjacent to the outdoor heat exchanger 19.
[0023]
On the other hand, the indoor units 12A, 12B,... Are installed indoors, indoor heat exchangers 21A, 21B,... Are disposed in the indoor refrigerant pipes 15A, 15B, respectively, and indoor heat is generated in the indoor refrigerant pipes 15A, 15B,. In the vicinity of the exchangers 21A, 21B, etc., electric expansion valves 22A, 22B,. The indoor heat exchangers 21A, 21B,... Are adjacent to indoor fans 23A, 23B, which send air to the indoor heat exchangers 21A, 21B,.
[0024]
The control device 13 controls the operation of the outdoor unit 11 and the indoor units 12A, 12B..., Specifically, the compressor 16, the four-way valve 18, the outdoor fan 20, and the electric expansion valve 24 in the outdoor unit 11. In addition, the electric expansion valves 22A, 22B, and the indoor fans 23A, 23B, etc. in the indoor units 12A, 12B,.
[0025]
When the four-way valve 18 is switched by the control device 13, the air conditioner 10 is set to the cooling operation or the heating operation. That is, when the control device 13 switches the four-way valve 18 to the cooling side, the refrigerant flows as indicated by solid line arrows, the outdoor heat exchanger 19 becomes a condenser, the indoor heat exchangers 21A, 21B. The indoor heat exchangers 21A, 21B,... Of the indoor units 12A, 12B,. Further, when the control device 13 switches the four-way valve 18 to the heating side, the refrigerant flows as indicated by broken arrows, the indoor heat exchangers 21A, 21B,... Become condensers, and the outdoor heat exchanger 19 becomes an evaporator for heating. It will be in an operation state and indoor heat exchanger 21A, 21B ... of indoor unit 12A, 12B ... will heat a room.
[0026]
Further, the control device 13 adjusts the valve opening degree of the electric expansion valve 22A in the indoor unit 12A according to the air conditioning load (refrigerant load) of the indoor unit 12A, controls the indoor fan 23A in the indoor unit 12A, According to the air conditioning load of the indoor unit 12B, the valve opening degree of the electric expansion valve 22B in the indoor unit 12B is adjusted to control the indoor fan 23B in the indoor unit 12B. The control device 13 similarly controls other indoor units. The adjustment of the valve opening degree of the electric expansion valves 22A, 22B... In the indoor units 12A, 12B.
[0027]
Each of the indoor units 12A, 12B... Has an inlet side refrigerant temperature sensor 25A, 25B... On the inlet side of the indoor heat exchangers 21A, 21B. Sensors 26A, 26B,. The control unit 13 receives the inlet side refrigerant temperatures in the indoor heat exchangers 21A, 21B,... From the inlet side refrigerant temperature sensors 25A, 25B, and the indoor heat exchanger 21A from the outlet side refrigerant temperature sensors 26A, 26B,. , 21B... Are transmitted. Further, each of the indoor units 12A, 12B,... Is provided with a blowing temperature sensor 27A, 27B,... On the air blowing side of each indoor heat exchanger 21A, 21B. The temperature of the air blown out from each indoor heat exchanger 21A, 21B... (Blowing temperature) is transmitted to the control device 13 from each of the blowout temperature sensors 27A, 27B.
[0028]
Further, the control device 13 has a target inlet / outlet refrigerant temperature that is a target value of a difference between the outlet side refrigerant temperature and the inlet side refrigerant temperature (hereinafter referred to as an inlet / outlet refrigerant temperature difference) for each of the indoor heat exchangers 21A, 21B. The difference is stored. Further, the control device 13 stores a target blowing temperature that is a target value of the blowing temperature for each of the indoor heat exchangers 21A, 21B.
[0029]
Then, the control device 13 compares the inlet / outlet refrigerant temperature difference and the target inlet / outlet refrigerant temperature difference for each of the indoor heat exchangers 21A, 21B, and when the inlet / outlet refrigerant temperature difference is larger than the target inlet / outlet refrigerant temperature difference, the air conditioning load It is determined that the (refrigerant load) has increased, the valve openings of the electric expansion valves 22A, 22B,... Are increased, the refrigerant flow rate flowing to the indoor heat exchangers 21A, 21B,. Increase the air conditioning capacity of 21B. On the other hand, when the inlet / outlet refrigerant temperature difference for each of the indoor heat exchangers 21A, 21B... Is smaller than the target inlet / outlet refrigerant temperature difference, it is determined that the air conditioning load has decreased, and the electric expansion valves 22A, 22B. And the superheat degree control operation is performed by reducing the flow rate of the refrigerant flowing into the indoor heat exchangers 21A, 21B... To prevent liquid back to the compressor 16.
[0030]
By the way, the control apparatus 13 sets the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference set for each indoor heat exchanger 21A, 21B..., The blowing temperature and the target blowing temperature for each indoor heat exchanger 21A, 21B. Are changed for each indoor unit 12A, 12B,. Further, when the priority order is set for the indoor units 12A, 12B, the control device 13 sets the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference set for the indoor heat exchangers 21A, 21B,. .. Are changed for each indoor unit 12A, 12B... Based on the blowout differential temperature of each indoor heat exchanger 21A, 21B.
[0031]
For example, as shown in FIG. 2, the control device 13 is an indoor unit 12 </ b> A, 12 </ b> B during operation (during thermo-ON) that changes the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference during the cooling operation of the air conditioner 10. The i-th machine is identified (S1).
[0032]
Next, it is determined whether or not a priority is set for the indoor units 12A, 12B... (S2). When the priority order is not set, the blowout differential temperature for the i-th of the indoor units 12A, 12B... Is not less than 5 ° C. as the predetermined value A, or is 3 as the predetermined value B, for example. It is determined whether the temperature is equal to or lower than 0 ° C. or between 3 ° C. and 5 ° C., for example (S3).
[0033]
When the outlet temperature difference is 5 ° C. or more, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B,. For example, it sets to 1.0-4.0 degreeC, and increases the valve opening degree of electric expansion valve 22A, 22B ... in the i-unit among indoor unit 12A, 12B ... (S4-1). Thereby, the refrigerant | coolant flow volume which flows into the indoor heat exchanger 21A, 21B ... of i unit among indoor unit 12A, 12B ... is increased, and the cooling capacity of indoor heat exchanger 21A, 21B ... of this i unit is improved.
[0034]
When the discharge differential temperature is 3 ° C. or less, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B,. The temperature is set to 0.0 to 8.0 ° C., and the opening degrees of the electric expansion valves 22A, 22B... In the i-th of the indoor units 12A, 12B. At this time, since it can be determined that the cooling of the i-th of the indoor units 12A, 12B... Is performed to some extent, the opening degree of the electric expansion valves 22A, 22B. The refrigerant flow rate flowing into the indoor heat exchangers 21A, 21B... Of the No. i machine is reduced, and the superheat degree control operation is performed to prevent liquid back to the compressor 16.
[0035]
When the blowout differential temperature is 3 to 5 ° C., the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B of the indoor units 12A, 12B. For example, it sets to 1.0-6.0 degreeC, and sets the valve opening degree of the electric expansion valves 22A, 22B ... in the i-unit among the indoor units 12A, 12B ... to an intermediate opening degree (S4). -3).
[0036]
On the other hand, if the priority order is set for the indoor units 12A, 12B... In the determination in step S2, the priority order of the i-th unit among the indoor units 12A, 12B. It is determined whether it is present or the third or later (S5).
[0037]
When the i-th unit among the indoor units 12A, 12B... Has the highest priority, the blowing differential temperature of the i-th unit is 3 ° C. or more as the predetermined value A, or 1 ° C. as the predetermined value B, for example. It is determined whether it is below or between 1 to 3 ° C. (S6).
[0038]
When the blowout differential temperature is 3 ° C. or more, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B,. It sets to 1.0-3.0 degreeC, and increases the valve opening degree of the electric expansion valve 22A, 22B ... of the i-unit among the indoor units 12A, 12B ... (S7-1). The cooling capacity of the indoor heat exchangers 21A, 21B,.
[0039]
When the blowout differential temperature is 1 ° C. or less, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B,. It sets to 1.0-8.0 degreeC, and the valve opening degree of the electric expansion valve 22A, 22B ... in the i-unit among the indoor units 12A, 12B ... is decreased (S7-2). It is determined that the cooling is sufficiently performed by the indoor units 12A, 12B... Of the unit No., and the superheat control operation is performed.
[0040]
When the blowout differential temperature is between 1 and 3 ° C., the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B of the i-unit among the indoor units 12A, 12B. A typical width, for example, 1.0 to 5.0 ° C. is set, and the opening degree of the electric expansion valves 22A, 22B,.
[0041]
When the i-th unit of the indoor units 12A, 12B... Has the second priority, the blowing differential temperature of this i-th unit is 4 ° C. or more as the predetermined value A, or 2 ° C. or less as the predetermined value B, for example. It is determined whether or not it is between 2 and 4 ° C., for example (S8).
[0042]
When the blowout differential temperature is 4 ° C. or more, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B... The valve opening degree of the electric expansion valves 22A, 22B... Of this i-th unit is increased to 0.0 to 4.0 ° C. (S9-1).
[0043]
When the discharge differential temperature is 2 ° C. or less, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B,. It sets to 1.0-8.0 degreeC, and the valve opening degree of electric expansion valve 22A, 22B ... of this i machine is decreased (S9-2).
[0044]
When the outlet differential temperature is between 2 and 4 ° C., the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B. An intermediate width, for example, 1.0 to 6.0 ° C. is set, and the valve openings of the electric expansion valves 22A, 22B,.
[0045]
When the i-th of the indoor units 12A, 12B... Has the third or higher priority, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference for the indoor heat exchangers 21A, 21B. For example, it sets to 1.0-8.0 degreeC, and superheat degree control driving | operation is implemented (S10). This control range value 1.0 to 8.0 ° C. is the same for all indoor units 12A, 12B.
[0046]
As described above, when the priority of the i-th unit among the indoor units 12A, 12B... Is high, the control device 13 also performs step S7 in the case of the same outlet differential temperature (for example, 3 ° C.) as compared to the low case. −1, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference is set narrower than in the case of step S9-3 to increase the valve opening of the electric expansion valves 22A, 22B. , 21B... Control is performed to increase the cooling capacity.
[0047]
Note that when there is only the highest priority and other cases, and there is no second indoor unit 12A, 12B,... In FIG. 2, steps S8, S9-1, S9-2 and S9-3 are omitted. To do. Further, in the present embodiment, the case where the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference in the indoor heat exchangers 21A, 21B,... Of the indoor units 12A, 12B,. However, even in the case of heating operation, although it is necessary to change the value of the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference, it can be similarly applied.
[0048]
Therefore, according to the above embodiment, the following effects (1) to (3) are obtained.
[0049]
(1) Since the control device 13 is configured to change the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference based on the outlet differential temperature, the target inlet / outlet refrigerant temperature when the outlet differential temperature is equal to or greater than the predetermined value A. The control range of the lower limit value of the difference is set narrow to increase the valve opening degree of the electric expansion valves 22A, 22B... Thereby increasing the cooling / heating capacity of the indoor heat exchangers 21A, 21B. Is less than the predetermined value B, the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference is set wide to reduce the valve opening degree of the electric expansion valves 22A, 22B, and thereby the superheat control operation is performed. Thus, liquid back to the compressor 16 is prevented. As a result, it is possible to carry out in a well-balanced manner the operation for exerting the cooling / heating capability by the indoor heat exchangers 21A, 21B... And the superheat control operation.
[0050]
(2) The control device 13 is configured to change the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference in the indoor heat exchangers 22A, 22B for each of the plurality of indoor units 12A, 12B. The indoors can be well cooled and heated by all the indoor units 12A, 12B.
[0051]
{Circle around (3)} The control device 13 determines the indoor heat exchanger 21A based on the priority set for the indoor units 12A, 12B... And the blowout differential temperatures of the indoor heat exchangers 21A, 21B. , 21B... Change the lower limit control range of the target inlet / outlet refrigerant temperature difference, the indoor units 12A, 12B... With higher priority are compared with the indoor units 12A, 12B. , 12B ..., the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference in the indoor heat exchangers 21A, 21B ... is set narrow with respect to the same outlet differential temperature, and the valve opening degree of the flow control valve of the indoor unit is set. By increasing, the indoor units 12A, 12B,... With higher priority can increase the cooling / heating capacity.
[0052]
As mentioned above, although this invention was demonstrated based on one Embodiment, this invention is not limited to this. For example, in the present embodiment, the case where the air conditioner 10 is a multi-type in which the air conditioner 10 includes a plurality of indoor units 12A, 12B,... Has been described.
[0053]
【The invention's effect】
As described above, according to the air conditioner according to the present invention, the control device is configured to control the indoor heat based on the blowing differential temperature that is the temperature difference between the blowing temperature of the air blown from the indoor heat exchanger and the target blowing temperature. Since the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference in the inlet / outlet refrigerant temperature difference, which is the difference between the inlet side refrigerant temperature and the outlet side refrigerant temperature of the exchanger, is changed, the flow control valve of the indoor unit It is possible to optimally control the valve opening so that the operation for exerting the air conditioning capability by the indoor heat exchanger and the superheat degree control operation can be performed in a well-balanced manner.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of an air conditioner according to the present invention.
FIG. 2 is a flowchart when the control device of FIG. 1 changes the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference in the indoor heat exchanger during the cooling operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Air conditioning apparatus 11 Outdoor unit 12A, 12B ... Indoor unit 13 Controller 15A, 15B ... Indoor refrigerant piping 16 Compressor 19 Outdoor heat exchanger 21A, 21B ... Indoor heat exchanger 22A, 22B ... Electric expansion valve 25A, 25B ... Inlet side refrigerant temperature sensor 26A, 26B ... Outlet side refrigerant temperature sensor 27A, 27B ... Blowout temperature sensor

Claims (1)

An outdoor unit including a compressor and an outdoor heat exchanger, an indoor unit including an indoor heat exchanger and a flow rate adjusting valve for adjusting a flow rate of refrigerant flowing to the indoor heat exchanger, and controlling the outdoor unit and the indoor unit And a control device that
The control device compares the inlet / outlet refrigerant temperature difference, which is the difference between the inlet side refrigerant temperature and the outlet side refrigerant temperature in the indoor heat exchanger, with the target inlet / outlet refrigerant temperature difference, and determines the valve opening degree of the flow rate adjustment valve. In the air conditioner to control,
Multiple indoor units are installed with priority,
The control device changes the control range of the lower limit value of the target inlet / outlet refrigerant temperature difference based on the outlet differential temperature which is the temperature difference between the outlet temperature of the air blown out from the indoor heat exchanger and the target outlet temperature, and gives priority The control range of the lower limit value of the indoor unit with a higher order is set narrower with respect to the same outlet differential temperature than that with a lower priority order, and the valve opening degree of the flow control valve of the indoor unit is increased. An air conditioner characterized.

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