JPH04131661A - Air conditioning apparatus - Google Patents

Abstract

PURPOSE:To always maintain refrigerant superheat degree a predetermined value in each indoor heat exchanger at the time of room cooling by controlling the capacity of a compressor in response to the total sum of requested capacities of respective indoor units, detecting total refrigerant superheat degree in each indoor heat exchanger, and deciding the total opening of each electrically-driven expansion valve necessary to maintain it the predetermined value. CONSTITUTION:A compressor 1 is started, refrigerant to be discharged from the compressor 1 is fed through a four-way valve 2, an outdoor heat exchanger 3, electrically-driven expansion valves 11, 12, indoor heat exchangers 12, 22 and the valve 2, and room cooling parallel operation of indoor units B1, B2 is started. The capacity of the compressor 1 is controlled in response to the total sum of the requested capacities of the units B1, B2. at the time of parallel room cooling. Further, total refrigerant heating degree (= a difference of saturated temperature sensed by a refrigerant temperature sensor 7 and sensed temperature of a refrigerant temperature sensor 8) in the exchangers 12, 22 is detected, and the total valve travel of the valves 11, 12 necessary to maintain the refrigerant superheat degree the predetermined value is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an air conditioner comprising an outdoor unit and a plurality of indoor units.

(Prior Art) In general, in multi-type air conditioners consisting of an outdoor unit and multiple indoor units, the capacity of the compressor is controlled according to the total required capacity of each indoor unit, and the Some pipes are each provided with an electric expansion valve, and these electric expansion valves are controlled as follows.

That is, during cooling operation, the overall degree of refrigerant superheat in each indoor unit is detected, and the total opening degree of each electric expansion valve required to maintain the detected degree of refrigerant superheat at a constant value is determined. Then, the allocation of the opening degree of each electric expansion valve is controlled within the range of the total opening degree determined above and according to the ratio of the required capacities of each indoor unit.

During heating operation, the degree of superheating of the refrigerant in the outdoor unit is detected,
The total opening degree of each electric expansion valve required to maintain the detected refrigerant superheat degree at a constant value is determined. Then, the allocation of the opening degree of each electric expansion valve is controlled within the range of the total opening degree determined above and according to the ratio of the required capacities of each indoor unit.

(Problems to be Solved by the Invention) By the way, in the above-mentioned air conditioner, during cooling operation, and when there is a large difference in the required capacity of each indoor unit, the following problem occurs.

In other words, there is no problem because a sufficient amount of refrigerant flows to the indoor unit with the higher required capacity, but since the amount of refrigerant flowing to the indoor unit with the lower required capacity is originally small, the refrigerant is overheated by the electric expansion valve. Temperature control does not work effectively, and the refrigerant superheat degree tends to exceed it.

When the degree of superheating of the refrigerant becomes excessive, a partial non-dehumidifying area is created in the indoor heat exchanger that acts as an evaporator, so that the air that passes through the indoor heat exchanger becomes a mixture of dehumidified air and non-dehumidified air. This mixed air causes dew condensation in the ventilation passages and the vicinity of the air outlet inside the indoor unit.

This invention was developed in consideration of the above circumstances, and its purpose is to maintain the degree of superheating of the refrigerant in each indoor heat exchanger at a constant value during cooling operation, and thereby It is an object of the present invention to provide an air conditioner whose entire area can be used as a dehumidifying area, and which can prevent dew condensation by eliminating the mixing of dehumidified air and non-dehumidified air.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides an air conditioner consisting of an outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of indoor units each having an indoor heat exchanger. a refrigeration cycle in which parallel circuits of the compressor, outdoor heat exchanger, and each indoor heat exchanger are connected; and an electric expansion valve provided in each liquid pipe between the outdoor heat exchanger and each indoor heat exchanger; Means for executing cooling operation by passing refrigerant discharged from the compressor through an outdoor heat exchanger, each electric expansion valve, and each indoor heat exchanger; means for controlling according to the total capacity; and means for detecting the overall degree of refrigerant superheating in each of the indoor heat exchangers during cooling operation;
means for determining the total opening degree of each of the electric expansion valves necessary to maintain the detected refrigerant superheat degree at a constant value; and a means for determining the total opening degree of each of the electric expansion valves during cooling operation; means for controlling the allocation within the range of and according to the ratio of required capacities of each of the indoor units; a means for detecting the outflow refrigerant temperature of each of the indoor heat exchangers during cooling operation; and a difference between these detected outflow refrigerant temperatures. and means for increasing, by a predetermined value, the opening degree of the electric expansion valve corresponding to the one having a higher detected outflow refrigerant temperature among the electric expansion valves when the calculated difference is greater than or equal to a set value. Be prepared.

(Function) During cooling operation, the capacity of the compressor is controlled according to the total required capacity of each indoor unit, and the overall degree of refrigerant superheating in each indoor heat exchanger is detected, and the detected degree of refrigerant superheating is Determine the total opening of each electric expansion valve required to maintain the constant value. Then, the allocation of the opening degree of each electric expansion valve is controlled within the range of the total opening degree determined above and according to the ratio of the required capacities of each indoor unit.

Furthermore, the outflow refrigerant temperature of each indoor heat exchanger is detected, and the difference between these detected outflow refrigerant temperatures is determined.

If the calculated difference is equal to or greater than the set value, the opening degree of the electric expansion valve corresponding to the one having the higher detected outflow refrigerant temperature is increased by a predetermined value.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 1, A is an outdoor unit and B l *B2 is an indoor unit.

This outdoor unit A and indoor unit B 1 +B2
The following heat pump refrigeration cycle is constructed.

An outdoor heat exchanger 3 is connected to the discharge port of the compressor 1 via a four-way valve 2, and a pair of liquid side branch pipes w1. Connect indoor heat exchanger 12.22 via W2.

The above liquid side branch pipe w1. Electric expansion valve 11.2 for each W2
1 will be provided.

Gas side branch pipe G 1 + G2 to indoor heat exchanger 12.22,
Gas side main pipe G where the same gas side branch pipe G 1 + 02 joins
1 and the suction port of the compressor 1 is connected through the four-way valve 2.

An outdoor fan 4 is provided near the outdoor heat exchanger 3, and an indoor fan 13.23 is provided near each of the indoor heat exchangers 12.22.
will be established.

A refrigerant temperature sensor 1424 is attached to each gas side branch pipe G 1 + 02. This refrigerant temperature sensor 14.24 serves as a means for detecting the temperature of the refrigerant flowing out of the indoor heat exchanger 12.22.

One end of a bypass 5 is connected to the liquid side main pipe W, and the other end of the bypass is connected to the suction port of the compressor 1 via a capillary tube 6.

In the bypass 5, a refrigerant temperature sensor 7 is attached to the downstream side of the capillary tube 6.

A refrigerant temperature sensor 8 is installed slightly upstream of the connection port of the bypass 5 in a pipe communicating with the suction port of the compressor 1.

The control circuit is shown in FIG.

The outdoor unit A has an outdoor control section 30.

The outdoor control section 30 is composed of a microcomputer and its peripheral circuits, and performs overall control of the outdoor unit A.

This outdoor control unit 30 includes an electric expansion valve 11.21, a four-way valve 2, an outdoor fan motor 4M, and a refrigerant temperature sensor 14.24.
, 7, 8, and the inverter circuit 31 are connected.

The inverter circuit 31 rectifies the voltage of the commercial AC power supply 32, converts it into an AC voltage of a predetermined frequency and level according to a command from the outdoor control unit 30, and outputs the AC voltage.

This output is supplied to the compressor motor IM as driving power.

Each indoor unit B1 has an indoor control section 40.

The indoor control section 40 is composed of a microcomputer and its peripheral circuits, and performs overall control of the indoor unit B1.

To this indoor control section 40, an indoor temperature sensor 41, an indoor fan motor 13M1, and a remote control operation section (hereinafter abbreviated as remote control) 50 are connected.

Each indoor unit B2 has an indoor control section 40.

The indoor control section 40 is composed of a microcomputer and its peripheral circuits, and performs overall control of the indoor unit B2.

To this indoor control section 40, an indoor temperature sensor 41, an indoor fan motor 23M1, and a remote control operation section (hereinafter abbreviated as remote control) 50 are connected.

Then, these indoor control units 40 are connected to the power supply line A, respectively.
Outdoor control unit 30 via CL and serial signal line SL
Connect to.

The indoor control unit 40 includes the following functional means.

- Means for sending operation mode commands and set indoor temperature data by operating the remote controller 50 to the outdoor control unit 30 in serial signals synchronized with the power supply voltage.

(2) Means for detecting the difference (that is, air conditioning load) between the temperature detected by the indoor temperature sensor 41 and the indoor temperature set by the remote controller 50, and transmitting it to the outdoor control unit 30 as the required capacity and as a serial signal synchronized with the power supply voltage.

The outdoor control unit 30 includes the following functional means.

■Based on the cooling operation mode command from the indoor units B, B2, the refrigerant discharged from the compressor 1 is transferred to the four-way valve 2, the outdoor heat exchanger 3, the electronic expansion valves 11, 21, . indoor heat exchangers 12, 22,
Means to flow through the four-way valve 2 and execute cooling operation.

■ During cooling operation, the capacity of compressor 1 (-inverter circuit 31
(output frequency) according to the total required capacity of the indoor unit B1+82.

(2) Means for detecting the overall degree of superheating of the refrigerant in the indoor heat exchanger 12.22 (-the difference between the saturation temperature detected by the refrigerant temperature sensor 7 and the temperature detected by the refrigerant temperature sensor 8) during cooling operation.

(2) Means for determining the total opening degree of the electric expansion valves 11 and 21 necessary to maintain the detected refrigerant superheat degree at a constant value during cooling operation.

■ During cooling operation, the opening degree of the electric expansion valve 11.21 is within the range of the total opening degree determined above, and the indoor unit 12.22
A means of controlling allocation according to the ratio of required capacities.

(2) Means for determining the difference in temperature of the refrigerant flowing out of the indoor heat exchangers 12 and 22 (-temperature detected by the refrigerant temperature sensors 14 and 24) during cooling operation.

(2) Means for increasing the opening degree of the electric expansion valve 11.21 corresponding to the one having the higher detected outflow refrigerant temperature by a predetermined value when the calculated difference is equal to or higher than a set value during cooling operation.

■Based on the heating operation mode command from the indoor units Bl and B2, the refrigerant discharged from the compressor 1 is passed through the four-way valve 2, the indoor heat exchangers 12 and 22, the electronic expansion valves 11 and 21, and the outdoor heat exchanger 3. , means for carrying out heating operation.

■ During heating operation, the capacity of compressor 1 (-inverter circuit 31
output frequency) of indoor unit B,.

Means for controlling according to the total required capacity of B2.

[Phase] During heating operation, the degree of superheating of the refrigerant in the outdoor heat exchanger 3 (-
Means for detecting the difference between the saturation temperature detected by the refrigerant temperature sensor 7 and the temperature detected by the refrigerant temperature sensor 8.

(2) Means for determining the total opening degree of the electric expansion valves 11 and 21 necessary to maintain the detected refrigerant superheat degree at a constant value during heating operation.

O During heating operation, the opening degree of the electric expansion valve 11.21 is within the range of the total opening degree determined above, and the indoor unit 12.22
A means of controlling allocation according to the ratio of required capacities.

Next, the operation of the above configuration will be explained with reference to the flowchart of FIG. 3.

Indoor unit B1. It is assumed that the cooling operation mode and the desired indoor temperature are set using the remote controllers 50 of B2, and the operation is started.

In this case, the compressor 1 is started and the refrigerant discharged from the compressor 1 is transferred to the four-way valve 2, the outdoor heat exchanger 3, the electronic expansion valves 11 and 21, and the indoor heat exchanger 12 as shown by the solid arrow in FIG. ,22
, through the four-way valve 2, and the indoor unit B1. Start cooling parallel operation of B2.

During this cooling parallel operation, the capacity of the compressor 1 (-the output frequency F of the inverter circuit 31) is controlled according to the sum of the required capacities of the indoor units B, B2.

Furthermore, the overall degree of superheating of the refrigerant in the indoor heat exchanger 512.22 (-the difference between the saturation temperature detected by the refrigerant temperature sensor 7 and the temperature detected by the refrigerant temperature sensor 8) is detected, and the degree of refrigerant superheating is set to a constant value. Determine the total opening degree of the electric expansion valve 11.21 required to maintain .

Then, the allocation of the opening degrees of the electric expansion valves 11.21 is controlled within the range of the total opening degree determined above and according to the ratio of the required capacities of the indoor units 12.22.

Therefore, while maintaining the overall refrigerant superheat degree in the indoor heat exchanger 12.22 at a constant value, the indoor heat exchanger 12.2
It is possible to distribute and supply refrigerant in an amount corresponding to the required capacity of each of the two.

Also, during this cooling operation, the absolute difference between the temperature detected by the refrigerant temperature sensor 14, that is, the outflow refrigerant temperature Tel of the indoor heat exchanger 12, and the temperature detected by the refrigerant temperature sensor 24, that is, the outflow refrigerant temperature Tc2 of the indoor heat exchanger 22. The value ΔTc (-1TcI
−Tc:2 1), and its ΔTc and set value ΔTc
Compare with s.

In this comparison, when ΔTc becomes larger than the set value ΔTcs, the opening degree of the electric expansion valve 11.21 corresponding to the higher of the detected outflow refrigerant temperatures Tel and Tc2 is increased by a predetermined value.

That is, for example, when the required capacity of indoor unit B is large and the required capacity of indoor unit B2 is small, while a sufficient amount of refrigerant flows to indoor unit B1, the amount of refrigerant that flows to indoor unit B2 decreases. The refrigerant superheat degree control by the electric expansion valve 21 does not work effectively, and the refrigerant superheat degree in the indoor heat exchanger 22 tends to be excessive.

When the degree of superheating of the refrigerant in the indoor heat exchanger 22 becomes excessive,
A situation occurs in which the outflow refrigerant temperature Tc2 rises and ΔTc becomes larger than the set value ΔTcs as described above.

At this time, the opening degree of the electric expansion valve 21 corresponding to the higher outflow refrigerant temperature Tc2 is increased by a predetermined value. This increase in the opening is due to the decrease in the outflow refrigerant temperature Tc2 and the set value ΔTc.
Repeat this until it becomes smaller than s.

When the opening degree of the electric expansion valve 21 increases, the amount of refrigerant flowing into the indoor unit B2 increases, and the degree of refrigerant superheat control by the electric expansion valve 21 becomes effective.

If the refrigerant superheat degree control works effectively, the refrigerant superheat degree in the indoor heat exchanger 22 can be maintained in an optimal state, and the entire indoor heat exchanger 22 functions as a dehumidifying area.

Therefore, the air that has passed through the indoor heat exchanger 22 does not contain non-dehumidified air and becomes only dehumidified air, and no dew condensation occurs near the ventilation path or outlet inside the indoor unit B2.

The required capacity of indoor unit B2 is large, and indoor unit B
Even when the required capacity of unit B1 is small, condensation phenomenon in indoor unit B1 can be similarly prevented.

In addition, in the above embodiment, the case where the number of indoor units is two was explained as an example, but it is possible to implement the case with a larger number of indoor units in the same way.

[Effects of invention As described above, according to the present invention, there is provided a compressor.

In an air conditioner consisting of an outdoor unit having an outdoor heat exchanger and a plurality of indoor units each having an indoor heat exchanger, the compressor, the outdoor heat exchanger, and the parallel circuit of each indoor heat exchanger are connected to each other. A cycle, an electric expansion valve provided in each liquid pipe between the outdoor heat exchanger and each indoor heat exchanger, and a refrigerant discharged from the compressor to the outdoor heat exchanger, each electric expansion valve, and each indoor heat exchanger. means for controlling the capacity of the compressor in accordance with the total required capacity of each of the indoor units during the cooling operation; means for detecting the overall degree of superheating of the refrigerant at the time of cooling operation; means for controlling the allocation of the opening degree of each electric expansion valve within the range of the determined total opening degree and according to the required capacity ratio of each of the indoor units; means for detecting a difference between these detected outflow refrigerant temperatures, and when the calculated difference is equal to or greater than a set value, a means for detecting a difference between the detected outflow refrigerant temperatures corresponds to the one of the electric expansion valves having a higher outflow refrigerant temperature. Since it is equipped with means for increasing the opening degree of the electric expansion valve by a predetermined value, the degree of superheating of the refrigerant in each indoor heat exchanger can always be maintained at a constant value during cooling operation. It is possible to provide an air conditioner that can function as a dehumidifying area, eliminate mixing of dehumidified air and non-dehumidified air, and prevent dew condensation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a refrigeration cycle according to an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a control circuit according to the embodiment, and FIG. 3 is a flowchart for explaining the operation of the embodiment. It is. A... Outdoor unit, B1+ B2... Indoor unit, 1... Compressor, 2... Four-way valve, 3... Outdoor heat exchanger, 11.21... Electric expansion valve, 12. 22・
...Indoor heat exchanger, 7, 8, 14.24... Refrigerant temperature sensor, 30... Outdoor control section, 40... Indoor control section. Applicant's agent Patent attorney Takehiko Suzue Figure 2

Claims (1)

[Claims] An air conditioner comprising a compressor, an outdoor unit having an outdoor heat exchanger, and a plurality of indoor units each having an indoor heat exchanger, the compressor, the outdoor heat exchanger,
A refrigeration cycle in which parallel circuits of each indoor heat exchanger are connected,
An electric expansion valve is provided in each liquid pipe between the outdoor heat exchanger and each indoor heat exchanger, and the refrigerant discharged from the compressor is passed through the outdoor heat exchanger, each electric expansion valve, and each indoor heat exchanger. means for controlling the capacity of the compressor in accordance with the total required capacity of each of the indoor units during the cooling operation; means for detecting the degree of superheat of the refrigerant; means for determining the total opening degree of each of the electric expansion valves necessary to maintain the detected degree of superheat of the refrigerant at a constant value; means for allocating and controlling the opening degrees of the valves within the range of the determined total opening degrees and according to the ratio of required capacities of the respective indoor units; and means for detecting the temperature of the refrigerant flowing out of each of the indoor heat exchangers during cooling operation. and a means for determining the difference between these detected outflow refrigerant temperatures, and when the calculated difference is equal to or greater than a set value, means for determining the electric expansion valve corresponding to the one having a higher detected outflow refrigerant temperature among the electric expansion valves. An air conditioner characterized by comprising means for increasing the degree of opening by a predetermined value.