JP2955401B2 - Air conditioner - Google Patents

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 and enabling simultaneous operation of cooling and heating in each indoor unit.

[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 via a distribution unit, and each of the indoor units can simultaneously operate cooling and heating.

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.

[0004] In such an air conditioner, a large pressure difference exists between both ends of the two-way valve in a closed state. For this reason, when the two-way valve opens when the number of operating units changes, a sudden refrigerant flow occurs from the high pressure side to the low pressure side of the two-way valve, and large refrigerant noise and vibration occur in the distribution unit and the indoor unit. There is.

Therefore, conventionally, a bypass is connected in parallel with each two-way valve of the distribution unit, a capillary tube is provided in each bypass, and a bypass corresponding to the two-way valve to be opened is previously conducted. . This is to equilibrate the pressures at both ends of the two-way valve before the two-way valve opens, thereby preventing a rapid flow of the refrigerant when the two-way valve is opened.

[0006]

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

[0007] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an air conditioner that can eliminate refrigerant noise and vibration when the number of operating indoor units changes, without causing a complicated configuration and an increase in cost.

[0008]

An air conditioner according to the present invention comprises: an outdoor unit having a compressor and an outdoor heat exchanger; a plurality of indoor units each having an indoor heat exchanger; Refrigeration cycle in which a parallel circuit of a heat exchanger, an outdoor heat exchanger, and each indoor heat exchanger is connected by piping, a plurality of flow control valves provided on a liquid side pipe connected to each indoor heat exchanger of the refrigeration cycle, A plurality of two-way valves for switching the flow direction provided on the gas side pipe connected to each indoor heat exchanger, and opening and closing each two-way valve to select the flow and flow direction of the refrigerant to each indoor unit In the air conditioner that enables simultaneous operation of cooling and heating in each indoor unit and controls the opening degree of each flow control valve according to the required capacity of each indoor unit, the number of operating 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 is opened when the number of operating indoor units changes, the pressure difference between the two sides of the two-way valve has already been reduced.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

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

An outdoor heat exchanger 5 is connected to the discharge pipe 2b via a flow path when the four-way valve 4 returns. Similarly, the outdoor heat exchanger 5 is connected to the suction pipe 3b through a flow path when the four-way valve 4 is switched.
Connect. Note that the four-way valve 4 in FIG. 1 shows a state in which the switching operation is performed. The outdoor heat exchanger 5 includes a heating expansion valve 6.
And the liquid side pipe W via a parallel circuit of the check valve 7 and the liquid receiver 8.

A flow control valve (pulse motor valve; hereinafter abbreviated as PMV) 2 of the distribution unit B is connected to the liquid side pipe W.
Expansion valves 22, 32, 4 for cooling via 1, 31, 41
2 is connected. 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, respectively. The gas side tubes G ₁ , G ₂ , G ₃ are connected to the indoor heat exchangers 24, 34, 44. These gas side tubes G ₁ ,
G ₂ and G ₃ are each branched into two. Gas side tube G
_One of the branch pipes ₁ , G ₂ and G ₃ is connected to the suction pipe 3 a 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 2 b via the two-way valves 26, 36, 46 of the distribution unit B. The outdoor fan 1 is located near the outdoor heat exchanger 5.
0 is provided. 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 6 a is an accessory 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 portion 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 is controlled so that the detected degree of superheat is constant.
It has a function of adjusting the amount of refrigerant flowing to the outdoor heat exchanger 5. In the distribution unit B, the PMVs 21, 31, 41
The temperature sensor 2 is connected to the pipe between the check valves 23, 33 and 43.
Attach 7, 37, 47.

Among the branch pipes of the gas side pipes G ₁ , G ₂ , G ₃ , the temperature sensing parts 22 a, 32 a, 42 a are attached to the branch pipes on the two-way valves 26, 36, 46 side. This temperature sensing part 2
2a, 32a, 42a are cooling expansion valves 22, 32,
42 are attached parts.

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

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

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

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

Each of the indoor units C ₁ , C ₂ , and C ₃ has an indoor control section 90 comprising 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. And the control part 90 is provided with the following functional means.

(1) Means for transferring one of a cooling operation mode and a cooling capacity request and a heating operation mode and a heating capacity request to the distribution control unit 80 based on the operation of the operation unit 91. The outdoor control unit 70 and the multi control unit 80 include the following functional units.

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

(2) When determining the cooling operation mode, the compressor 1
Means for passing a part of the refrigerant discharged from the air conditioner through the indoor unit issuing the request for the heating operation mode, and then joining the refrigerant flow to the indoor unit issuing the request for 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 issuing the request for the heating operation mode, and then returning to the compressor 1 through the outdoor heat exchanger 5.

(4) When determining the heating operation mode, part of the refrigerant that has passed through the indoor unit that has issued the request for the heating operation mode is passed through the indoor unit that has issued the request for the cooling operation mode. Means to return to.

(5) When the number of operating indoor units changes, the high-pressure side and the low-pressure side of the refrigeration cycle are pressure-balanced for a predetermined time in advance with the flow control valve connected to the corresponding indoor unit fully opened. 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. 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 are opened (white display), the PMV 31 is closed (black display), the two-way valves 45, 26 and 36 are opened (white display), and the two-way valve 2 is opened.
5, 35 and 46 are closed (black display). That is, the gas-side pipe G ₁ of the indoor unit C ₁ making the request of the heating operation mode is connected to the discharge tube 2b of the compressor 1. Gas-side pipe G ₃ of the indoor units C ₃ making the request of the cooling operation mode is connected to the suction pipe 3a of the compressor 1.

Therefore, the refrigerant discharged from the compressor 1 is supplied to the indoor unit C ₁ that issues a request for the heating operation mode.
And then through the outdoor heat exchanger 5 and 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.

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 utilized 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 that can cover sufficiently large heating capacity of the indoor units C ₁ 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. The indoor unit C _3, the amount of refrigerant flowing into the indoor heat exchanger 44 is adjusted by the expansion valve 42, the degree of superheat of the refrigerant is kept 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 kept constant. Incidentally, the open two-way valve 35 corresponding to the stop the indoor unit C ₂ is for recovering the accumulated refrigerant in the indoor heat exchanger 34 by the suction pressure of the compressor 1. Then, it is assumed to start the heating operation of the indoor unit C _2. 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.

After a lapse of a predetermined time based on the count of the internal timer, for example, about 25 seconds, the four-way valve 4 is returned.
That is, while securing the flow state of slight refrigerant from the liquid side to the indoor units C _2, to a pressure balance a high pressure side and the low pressure side of the refrigeration cycle. This state is shown in FIG. At this time, the refrigerant flowing into the indoor unit C _2, by the synergistic action of the pressure balance of high and low pressures, both ends the pressure of the closed two-way valve 36 is reduced.

When several seconds, for example, 5 seconds, have elapsed since the return of the four-way valve 4, the four-way valve 4 is switched, 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, and sets in response to opening of PMV31 the required heating capacity of the indoor units C _2, return the output frequency F of the inverter circuit 71 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 no loud refrigerant noise or vibration is generated. In particular, since a conventional bypass or capillary tube is not used, the configuration is not complicated and the cost is not increased. When the two-way valve 36 is opened, the refrigerant flows into the indoor heat exchanger 34, and the indoor unit C
The heating operation of ₂ is started quietly.

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. 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 reset 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 opens, two-way valves 25, 35, and 46 open, two-way valve 2
6, 36, 45 close. That is, the gas side pipes G ₁ , G _{2 of the} indoor units C ₁ , C ₂ issuing the request for the cooling operation mode are connected to the suction pipe 3 a of the compressor 1.
Gas-side pipe G ₃ of the indoor units C ₃ making the request of the heating operation mode is connected to the discharge tube 2b of the compressor 1.

Accordingly, the refrigerant discharged from the compressor 1 passes through the outdoor heat exchanger 5, and then passes through the indoor units C ₁ and C ₂ which issue a request for the cooling operation mode.
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, a part of the heat absorption of the indoor units C ₁ and C ₂ is used as heat radiation 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 is provided with the indoor units C ₁ and C _{2 having} a large load.
Ability to provide sufficient cooling capacity.

[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 You. And the indoor heat exchangers 24, 34
The amount of the refrigerant flowing through is controlled by the expansion valves 22 and 32, and the degree of superheat of the refrigerant is kept constant.

With respect to 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 becomes constant.
The opening of the PMV 41 is controlled.

In the above embodiment, the indoor unit is 3
Although the case of the number of units has been described as an example, the number is not limited and can be set as appropriate. The outdoor unit A has a four-way valve 4
Although 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 opened for a predetermined period of time with the flow control valve connected to the corresponding indoor unit fully opened. A means for balancing the pressure between the high pressure side and the low pressure side of the air conditioner is provided, which can eliminate refrigerant noise and vibration when the number of operating indoor units changes, without complicating the configuration and increasing the cost. Can be provided.

[Brief description of the drawings]

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

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

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

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

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

FIG. 6 is a diagram showing the movement of each valve when the number of operating vehicles increases 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 exchangers, 25, 35, 45, 26,
36, 46: Two-way valve.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F24F 11/02 102 F25B 13/00 104

Claims (1)

(57) [Claims] 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, the outdoor heat exchanger, and each indoor heat exchanger A refrigeration cycle connected by pipes to the parallel circuit, a plurality of flow control valves provided on a liquid side pipe connected to each indoor heat exchanger of the refrigeration cycle, and a gas side pipe connected to each indoor heat exchanger of the refrigeration cycle. Simultaneous operation of cooling and heating in each indoor unit by providing a plurality of two-way valves for switching the flow direction provided and selecting the flow and flow direction of refrigerant to each indoor unit by opening and closing each two-way valve And an air conditioner that controls the opening of each of the flow control valves in accordance with the required capacity of each indoor unit. An air conditioner characterized by comprising means for pressure-balancing the high-pressure side and the low-pressure side of the refrigeration cycle with the flow control valve connected to the unit fully opened.