JPH0526532A - Air-conditioner - Google Patents

Abstract

(57) [Summary] [Purpose] To eliminate refrigerant noise and vibration when the number of operating indoor units changes, without inviting complication of configuration and increase in cost. [Composition] A compressor 1, an outdoor heat exchanger 5 of an outdoor unit A, and a refrigeration cycle in which a parallel circuit of the indoor heat exchangers of a plurality of indoor units C ₁ , C ₂ , C ₃ is connected by piping.
Liquid side tube W connected to each indoor heat exchanger of this refrigeration cycle
And a plurality of two-way valves for switching the flow direction provided in the gas side pipe G connected to each indoor heat exchanger of the refrigeration cycle, each two-way valve being opened and closed. By selecting the flow direction and flow direction of the refrigerant to each indoor unit, it is possible to simultaneously operate cooling and heating in each indoor unit, and to set the opening of each flow rate adjustment valve according to the required capacity of each indoor unit. It is an air conditioner to be controlled, and when the number of operating indoor units C ₁ , C ₂ , C ₃ changes,
The high-pressure side and the low-pressure side of the refrigeration cycle are pressure balanced with the flow rate control valve connected to the corresponding indoor unit fully opened for a predetermined time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner having a plurality of indoor units, each of which enables simultaneous operation of cooling and heating.

[0002]

2. Description of the Related Art As an air conditioner, there is a multi-type air conditioner in which a plurality of indoor units are connected to one outdoor unit through a distribution unit and each indoor unit can simultaneously perform cooling and heating operations.

The distribution unit has a pair of two-way valves for switching the flow direction of the refrigerant to each indoor unit for each indoor unit, and opens and closes each two-way valve when the number of operating indoor units changes. To control the flow of the refrigerant.

By the way, in such an air conditioner, there is a large pressure difference between both ends of the two-way valve in the closed state. Therefore, when the two-way valve opens when the operating number changes, a sudden refrigerant flow occurs from the high-pressure side to the low-pressure side of the two-way valve, causing large refrigerant noise and vibration in the distribution unit and the indoor units. There is.

Therefore, conventionally, there is one in which a bypass is connected in parallel with each two-way valve of the distribution unit, and a capillary tube is provided in each bypass so that the bypass corresponding to the two-way valve to be opened is previously conducted. .. This is to balance the pressures at both ends of the two-way valve before the two-way valve is opened to prevent a sudden flow of the refrigerant when the two-way valve is opened.

[0006]

However, in the above air conditioner, the number of bypasses and capillary tubes corresponding to the number of two-way valves is required, which complicates the structure of the refrigeration cycle and increases the cost. There is a new problem of inviting.

The present invention takes the above circumstances into consideration,
It is an object of the present invention to provide an air conditioner capable of eliminating refrigerant noise and vibration when the number of operating indoor units changes, without inviting a complicated structure and an increase in cost.

[0008]

The air conditioner of the present invention comprises one outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, and the above-mentioned compression unit. Refrigeration cycle in which a parallel circuit of an air conditioner, an outdoor heat exchanger, and each indoor heat exchanger is connected by piping, a plurality of flow rate adjustment valves provided in a liquid side pipe connected to each indoor heat exchanger of this refrigeration cycle, And a plurality of two-way valves for switching the flow direction provided in the gas side pipe connected to each indoor heat exchanger, and opening and closing each two-way valve to select the flow direction and flow direction of the refrigerant to each indoor unit. This enables simultaneous operation of cooling and heating in each indoor unit, and in the air conditioner that controls the opening of each flow rate adjusting valve according to the required capacity of each indoor unit, the number of operating units of each indoor unit. Strange Upon advance a predetermined time, providing a means to pressure balance a high pressure side and the low pressure side of the refrigeration cycle while fully opening the flow control valve which is connected to the corresponding indoor unit.

[0009]

When the two-way valve opens when the number of operating indoor units changes, the pressure difference between both sides of the two-way valve is already small.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, one outdoor unit A
A plurality of indoor units C ₁ , C ₂ and C ₃ are connected to the pipe via the distribution unit B to form the next refrigeration cycle. First, the outdoor unit A has a variable capacity compressor 1. The discharge pipe 2 is connected to the discharge port of the compressor 1, and the suction pipe 3 is connected to the suction port. The discharge pipe 2 is divided into two discharge pipes 2a and 2b. The suction pipe 3 is divided into two suction pipes 3a and 3b.

An outdoor heat exchanger 5 is connected to the discharge pipe 2b through a flow path when the four-way valve 4 is returned. The outdoor heat exchanger 5 is also connected to the suction pipe 3b through the flow path when the four-way valve 4 is switched.
Connect. The four-way valve 4 shown in FIG. 1 is in a switching-operated state. The outdoor heat exchanger 5 has an expansion valve 6 for heating.
And the liquid side pipe W are connected via a parallel circuit of the check valve 7 and the liquid receiver 8.

A flow rate adjusting valve (pulse motor valve; hereinafter abbreviated as PMV) 2 of the distribution unit B is provided in the liquid side pipe W.
Expansion valves 22, 32, 4 for cooling via 1, 31, 41
Connect two. Check valves 23, 33, 43 are connected in parallel to the expansion valves 22, 32, 42.

The indoor heat exchangers 24, 34, 44 of the indoor units C ₁ , C ₂ , C ₃ are connected to the expansion valves 22, 32, 42. The gas side pipes G ₁ , G ₂ and G ₃ are connected to the indoor heat exchangers 24, 34 and 44. These gas side tubes G ₁ ,
G ₂ and G ₃ are each branched into two. Gas side tube G
_One branch pipe of ₁ , G ₂ and G ₃ is connected to the suction pipe 3a via the two-way valves 25, 35 and 45 of the distribution unit B.
The other branch pipe of the gas side pipes G ₁ , G ₂ , G ₃ is connected to the discharge pipe 2b via the two-way valves 26, 36, 46 of the distribution unit B. In addition, the outdoor fan 1 is provided near the outdoor heat exchanger 5.
0 is set. In the pipe between the four-way valve 4 and the outdoor heat exchanger 5,
Attach the temperature sensing part 6a. The temperature sensing part 6a is an accessory part of the expansion valve 6.

That is, the expansion valve 6 has a function of detecting the difference between the temperature sensed by the temperature sensing section 6a and the temperature of the refrigerant flowing through itself, that is, the degree of superheat of the refrigerant in the outdoor heat exchanger 5. Then, the expansion valve 6 adjusts the detected degree of superheat to be constant.
It has a function of adjusting the amount of the refrigerant flowing into the outdoor heat exchanger 5. In the distribution unit B, PMVs 21, 31, 41
The temperature sensor 2 is attached to the pipe between the check valve 23, 33 and 43.
Install 7, 37, 47.

Of the respective branch pipes of the gas side pipes G ₁ , G ₂ and G ₃ , the temperature sensitive portions 22a, 32a and 42a are attached to the branch pipes on the side of the two-way valves 26, 36 and 46. This temperature sensitive part 2
2a, 32a, 42a are expansion valves 22, 32 for cooling,
It is an accessory part of 42.

That is, the expansion valves 22, 32, 42 have a difference between the temperature sensed by the temperature sensing parts 22a, 32a, 42a and the temperature of the refrigerant flowing therein, that is, the indoor heat exchangers 24, 34, 44.
It has a function to detect the degree of superheat of the refrigerant. The expansion valves 22, 32, 42 have a function of adjusting the amount of refrigerant flowing through the indoor heat exchangers 24, 34, 44 so that the detected superheat degree becomes constant. The indoor fans 28, 38, 4 are provided near the indoor heat exchangers 24, 34, 44.
8 is provided. The control circuit is shown in FIG.

The outdoor unit A includes an outdoor control unit 70 including a microcomputer and its peripheral circuits.
An inverter circuit 71 and the four-way valve 4 are connected to the outdoor control unit 70.

The inverter circuit 71 is a commercial AC power source 72.
Is rectified and converted into an AC voltage of a predetermined frequency by switching according to a command from the outdoor control unit 70. This output voltage is supplied to the compressor motor 1M as drive power.

The distribution unit B includes a distribution control section 80 composed of a microcomputer and its peripheral circuits.
PMVs 21, 31, 41, two-way valves 25, 35, 45, two-way valves 26, 36, 46, and temperature sensors 27, 37, 47 are connected to the distribution control unit 80.

The indoor units C ₁ , C ₂ and C ₃ are provided with an indoor control section 90 composed of a microcomputer and its peripheral circuits. A remote control type operation unit 91 and a temperature sensor 92 are connected to the outdoor control unit 90. The control unit 90 includes the following functional means.

(1) Means for transferring to the distribution control unit 80 either one of a cooling operation mode and a cooling capacity request and a heating operation mode and a heating capacity request based on the operation of the operation section 91. In addition, the outdoor control unit 70 and the multi-control unit 80 include the following functional means.

(1) When the total cooling capacity required from each indoor unit is larger than the total heating capacity required from the remaining indoor units, the cooling operation mode is determined and the refrigerant discharged from the compressor 1 is removed. Means for returning to the compressor 1 through the outdoor heat exchanger 5, and then through the indoor unit that is requesting the cooling operation mode.

(2) When the cooling operation mode is determined, the compressor 1
A means for passing a part of the refrigerant discharged from the indoor unit requesting the heating operation mode and then joining the refrigerant to the indoor unit requesting the cooling operation mode.

(3) When the total heating capacity required from each indoor unit is larger than the total cooling capacity required from the remaining indoor units, the heating operation mode is determined and the refrigerant discharged from the compressor 1 is discharged. Means for passing through the indoor unit requesting the heating operation mode and then through the outdoor heat exchanger 5 to return to the compressor 1.

(4) When determining the heating operation mode, a part of the refrigerant passing through the indoor unit requesting the heating operation mode is passed through the indoor unit requesting the cooling operation mode, and then the compressor 1 Means to return to.

(5) When the number of operating indoor units is changed, the high-pressure side and the low-pressure side of the refrigeration cycle are pressure balanced with the flow rate adjusting valve connected to the corresponding indoor unit fully opened for a predetermined time. means. Next, the operation of the above configuration will be described.

It is assumed that the request of the indoor unit C ₁ is the heating operation mode, the operation of the indoor unit C ₂ is stopped, and the request of the indoor unit C ₃ is the cooling operation mode. Then, it is assumed that the total required heating capacity is larger than the total required cooling capacity.

In this case, the heating operation mode is determined, and the four-way valve 4 of the outdoor unit A is switched as shown in FIG. That is, the outdoor heat exchanger 5 is connected to the suction pipe 3b of the compressor 1.

In the switching unit B, the PMVs 21 and 41 open (white display), the PMV 31 closes (black display), the two-way valves 45, 26 and 36 open (white display), and the two-way valve 2
5, 35 and 46 are closed (displayed in black). That is, the gas side pipe G ₁ of the indoor unit C ₁ which issues the request for the heating operation mode is connected to the discharge pipe 2b of the compressor 1. The gas side pipe G ₃ of the indoor unit C ₃ requesting the cooling operation mode is connected to the suction pipe _{3 a} of the compressor 1.

Therefore, the refrigerant discharged from the compressor 1 is the indoor unit C ₁ which requests the heating operation mode.
Through the outdoor heat exchanger 5, and is sucked into the compressor 1. Furthermore, it enters the indoor unit C ₃ Some of the refrigerant which has flowed through the indoor unit C ₁ is requesting the cooling operation mode, the flow of the refrigerant of the refrigerant which has flowed through the indoor unit C ₃ is the suction side of the compressor 1 Join together.

That is, the indoor heat exchanger 24 functions as a condenser, the outdoor heat exchanger 5 functions as an evaporator, and the indoor heat exchanger 44 functions as an evaporator. In this case, the heat absorption of the outdoor heat exchanger 5 and the indoor heat exchanger 44 is used as the heat radiation of the indoor unit C ₁ .

The output frequency F of the inverter circuit 71 is set according to the total required heating capacity. Therefore, the compressor 1 emits a capacity capable of sufficiently covering the heating capacity of the indoor unit C _{1 having} a large load. At this time, the opening degree of PMV21 depending on the heating capability of the indoor unit C ₁ is requesting is controlled, through the proper amount of refrigerant to the indoor unit C _1. In the indoor unit C ₃ , the expansion valve 42 adjusts the amount of the refrigerant flowing through the indoor heat exchanger 44, so that the degree of superheat of the refrigerant is maintained constant. Further, the amount of the refrigerant flowing through the outdoor heat exchanger 5 is adjusted by the expansion valve 6,
The degree of superheat of the refrigerant is maintained constant. The two-way valve 35 corresponding to the stopped indoor unit C ₂ is opened in order to recover the refrigerant accumulated in the indoor heat exchanger 34 by the suction pressure of the compressor 1. After that, the heating operation of the indoor unit C ₂ is started. For the following actions,
This will be described with reference to FIG.

While maintaining the state of the two-way valves 35 and 36,
First, the PMV 31 is fully opened. This state is shown in FIG. At the same time, the output frequency F of the inverter circuit 71 is set to a set value lower than the normal control value.

When a predetermined time based on the count of the internal timer, for example, about 25 seconds has elapsed, the four-way valve 4 is returned.
That is, while maintaining a slight flow state of the refrigerant from the liquid side to the indoor unit C ₂ , the high pressure side and the low pressure side of the refrigeration cycle are pressure balanced. This state is shown in FIG. At this time, the pressure at both ends of the two-way valve 36 in the closed state becomes small due to the synergistic effect of the refrigerant flow into the indoor unit C ₂ and the pressure balance of high pressure and low pressure.

When several seconds, for example, 5 seconds have elapsed from the return of the four-way valve 4, the four-way valve 4 is switched and the two-way valve 35 is closed and the two-way valve 36 is opened. This state is shown in FIG. At the same time, the opening degree of the PMV 31 is set according to the required heating capacity of the indoor unit C ₂ , and the output frequency F of the inverter circuit 71 is returned to the normal control value.

At this time, since the pressure difference between the two ends of the two-way valve 36 is small, a sudden refrigerant flow does not occur when the two-way valve 36 is opened, so that a large refrigerant noise or vibration does not occur at all. In particular, since a bypass and a capillary tube as in the past are not used, the structure is not complicated and the cost is not increased. Then, by opening the two-way valve 36, the refrigerant flows into the indoor heat exchanger 34, and the indoor unit C
The heating operation of ₂ starts quietly.

By the way, it is assumed that the request of the indoor unit C ₁ is the cooling operation mode, the request of the indoor unit C ₂ is the cooling operation mode, and the request of the indoor unit C ₃ is the heating operation mode. Then, it is assumed that the total required cooling capacity is larger than the total required heating capacity. In this case, the cooling operation mode is determined and the four-way valve 4 of the outdoor unit A maintains the return state. That is, the outdoor heat exchanger 5 is connected to the discharge pipe 2a of the compressor 1.

In the switching unit B, the PMVs 21, 31,
41 is opened, two-way valves 25, 35, 46 are opened, two-way valve 2
6, 36 and 45 are closed. That is, the gas side pipes G ₁ and G _{2 of the} indoor units C ₁ and C ₂ that are requesting the cooling operation mode are connected to the suction pipe 3 a of the compressor 1.
The gas side pipe G ₃ of the indoor unit C ₃ requesting the heating operation mode is connected to the discharge pipe 2b of the compressor 1.

Therefore, the refrigerant discharged from the compressor 1 passes through the outdoor heat exchanger 5 and then through the indoor units C ₁ and C ₂ which are requesting the cooling operation mode, and then the compressor 1
Is sucked into. Furthermore, it enters the indoor unit C ₃ Some of the refrigerant discharged from the compressor 1 is requesting the heating operation mode, the refrigerant which has flowed through the indoor unit C ₃ is the requesting cooling operation mode indoor unit It joins the flow of the refrigerant to C ₁ and C ₂ .

That is, the outdoor heat exchanger 5 functions as a condenser, the indoor heat exchangers 24 and 34 function as an evaporator, and the indoor heat exchanger 44 functions as a condenser. In this case, part of the heat absorption of the indoor units C ₁ and C ₂ is used as heat dissipation of the indoor unit C ₃ .

The output frequency F of the inverter circuit 71 is set according to the total required cooling capacity. Therefore, the compressor 1 includes the indoor units C ₁ and C _{2 having} a large load.
Emits the ability to fully cover the cooling capacity of.

[0043] At this time, the control PMV21,31 opening in accordance with the cooling capacity which is required by the indoor unit C _1, C _2, the refrigerant is distributed to a proper state to the indoor unit C _1, C ₂ It And the indoor heat exchangers 24, 34
The amount of the refrigerant flowing through is adjusted by the expansion valves 22 and 32, and the degree of superheat of the refrigerant is maintained constant.

Regarding the indoor unit C ₃ , the temperature of the refrigerant flowing out of the indoor heat exchanger 44 is detected by the temperature sensor 47, and the detected temperature, that is, the degree of supercooling is constant.
The opening degree of the PMV 41 is controlled.

In the above embodiment, the number of indoor units is three.
Although the case of the number of units has been described as an example, the number of units is not limited and can be set appropriately. In addition, the outdoor unit A has a four-way valve 4
However, a plurality of two-way valves may be provided instead of the four-way valve.

[0046]

As described above, according to the present invention, when the number of operating indoor units changes, the refrigeration cycle is performed for a predetermined time while the flow control valve connected to the corresponding indoor unit is fully opened. Since a means for pressure-balancing the high-pressure side and the low-pressure side is provided, an air conditioner that can eliminate refrigerant noise and vibration when the number of operating indoor units is changed without complicating the configuration and increasing cost Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a control circuit of the same embodiment.

FIG. 3 is a time chart for explaining the operation of the embodiment.

FIG. 4 is a diagram showing the movement of each valve when the number of operating vehicles is increased in the embodiment.

FIG. 5 is a diagram showing the movement of each valve when the number of operating vehicles is increased in the embodiment.

FIG. 6 is a diagram showing the movement of each valve when the number of operating vehicles is increased in the embodiment.

[Explanation of symbols]

A ... Outdoor unit, B ... Distribution unit, C ₁ , C ₂ , C
₃ ... Indoor unit, 1 ... Variable capacity compressor, 4 ... Four-way valve,
5 ... Outdoor heat exchanger 21, 31, 41 ... PMV, 24,
34,44 ... Indoor heat exchanger, 25, 35, 45, 26,
36,46 ... Two-way valve.

Claims (1)

Claim: What is claimed is: 1. An outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, the compressor and an outdoor heat exchanger. A refrigeration cycle in which parallel circuits of the indoor heat exchangers are connected by piping, a plurality of flow rate adjusting valves provided in a liquid side pipe connected to the indoor heat exchangers of the refrigeration cycle, and the indoor heat exchangers of the refrigeration cycle Each of the indoor units is equipped with a plurality of two-way valves for switching the flow direction provided in the gas side pipe connected to, and by opening and closing each two-way valve to select the flow and flow direction of the refrigerant to each indoor unit. In an air conditioner that enables simultaneous operation of cooling and heating and controls the opening of each flow rate adjusting valve according to the required capacity of each indoor unit, a predetermined value is set in advance when the number of operating each of the indoor units is changed. Time Only the corresponding air conditioner, characterized in that a means for pressure balancing the high pressure side and low pressure side in a state of fully opening the flow control valve which is connected to the indoor unit refrigeration cycle.