JP3356485B2 - Multi-room 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 refrigeration cycle control of a multi-room air conditioner capable of simultaneous cooling operation, and more particularly to outdoor expansion valve control in a heating circuit.

[0002]

2. Description of the Related Art In recent years, in order to respond to improvement in comfort of an air-conditioning environment and energy saving, technology for controlling the capacity of a multi-room air conditioner has been advanced. It is being actively performed. In the outdoor expansion valve control, the upper and lower limits of the opening degree of the outdoor expansion valve are determined from the output frequency of the inverter as disclosed in Japanese Patent Application Laid-Open No. H4-190057. A system is used in which control is performed using the degree of superheat as an input.

Hereinafter, control of an outdoor expansion valve of the conventional multi-room air conditioner will be described. FIG. 4 is a control block diagram of a conventional multi-room air conditioner. 1 is an outdoor unit, a variable capacity compressor 2, a four-way valve 3, an outdoor heat exchanger 4,
It comprises an outdoor expansion valve 5. Reference numerals 6a and 6b denote indoor units, each of which comprises indoor expansion valves 7a and 7b and indoor heat exchangers 8a and 8b.
Are connected in parallel by pipes.

The variable capacity compressor 2 is connected to an inverter 11. Reference numeral 12 denotes a discharge pressure detecting means for detecting the discharge pressure of the variable capacity compressor 2. A superheat degree detecting means 13 is provided between the outdoor heat exchanger 4 and the variable capacity compressor 2. 14 is an outdoor expansion valve opening calculating means, 15 is an operating frequency calculating means, and 16 is an outdoor expansion valve control means, which are electrically connected as shown.

[0005] The operation of the conventional multi-room air conditioner configured as described above will be described below. At the time of the heating operation, the operating frequency calculating means 15 is provided with the discharge pressure detecting means 1.
The operating frequency is determined based on the discharge pressure detected by step 2 and the discharge pressure target value, the variable capacity compressor 2 is operated by the inverter 11, and the operation frequency is transmitted to the outdoor expansion valve control means 16.

[0006] The outdoor expansion valve opening calculating means 14 comprises:
The degree of opening of the outdoor expansion valve 5 is calculated based on the degree of superheat of the refrigerant detected by the degree of superheat detection means 13. Outdoor expansion valve control means 16
Determines an upper limit value and a lower limit value of the opening degree of the outdoor expansion valve 5 at the operating frequency determined by the operating frequency control means 15, and calculates the upper limit value and the lower limit value thereof and the outdoor outdoor expansion valve opening degree calculating means. The outdoor expansion valve 5 is driven in accordance with the calculation result of 14.

That is, by monitoring the operating frequency of the variable capacity compressor 2, the flow rate of the refrigerant to the outdoor heat exchanger 4 is estimated, and the opening range of the outdoor expansion valve 5 is set. The superheat degree of the refrigerant is appropriately controlled.

As described above, by controlling the outdoor expansion valve 5 based on both the flow rate of the refrigerant to the outdoor heat exchanger 4 and the degree of superheat of the refrigerant, even in a transition period when the refrigeration cycle changes, Even during steady operation, it can be operated in a stable and efficient state.

[0009]

However, in the conventional configuration described above, when a plurality of indoor units 6a and 6b perform heating operation at the same time, the refrigeration cycle can be operated in a stable and efficient state. When simultaneous cooling and heating operations are performed in the heating circuit in a possible refrigeration cycle, there is a refrigerant split between the indoor heat exchanger and the outdoor heat exchanger of the indoor unit during the cooling operation, so that the operation of the variable capacity compressor 2 is performed. Even if the frequency is monitored, the flow rate of the refrigerant to the outdoor heat exchanger 4 cannot be estimated, and the refrigeration cycle is normal even if the degree of superheat of the refrigerant at the outlet of the outdoor heat exchanger 4 increases. Since there may be a state, there has been a problem that the supply of the refrigerant to the indoor unit during the cooling operation is not properly performed, and it is difficult to control the cooling capacity.

According to the present invention, when simultaneous cooling and heating operations are performed in a heating circuit in a refrigeration cycle capable of simultaneous cooling and heating operation, the liquid refrigerant is transmitted to the indoor unit during the cooling operation without transmitting the control state of the indoor unit to the outdoor unit. It is an object of the present invention to provide a multi-room air conditioner that controls an outdoor expansion valve that can supply and appropriately control a cooling capacity.

[0011]

To achieve the above object, a multi-chamber air conditioner according to the present invention comprises: an outdoor unit comprising a variable capacity compressor, a four-way valve, an outdoor expansion valve, and an outdoor heat exchanger;
An indoor expansion valve, a plurality of indoor units including an indoor heat exchanger, a branch unit including a discharge-side electromagnetic valve and a suction-side electromagnetic valve for switching a flow direction of refrigerant to each indoor unit, the outdoor unit and the outdoor unit; It has a refrigerating cycle capable of simultaneous cooling and heating operation by connecting a plurality of indoor units via the branch unit via three pipes of a discharge gas pipe, a suction gas pipe, and a liquid pipe, and detects the pressure of the liquid pipe. Liquid pipe pressure detecting means,
The four-way valve has an outdoor expansion valve control means for controlling the valve opening of the outdoor expansion valve by using a detection value of the liquid pipe pressure detection means as an input when the heating circuit is set.

A receiver for storing the liquid refrigerant in the liquid pipe; a discharge gas bypass circuit for bypassing the discharge gas from the discharge pipe of the variable capacity compressor to an upper part of the receiver via a capillary tube; and a discharge gas bypass circuit. The liquid pipe pressure saturation temperature detecting means for detecting the refrigerant temperature in the middle of the process and indirectly detecting the pressure saturation temperature of the liquid pipe, and the four-way valve is provided with the detection value of the liquid pipe pressure saturation temperature detecting means as an input when the heating circuit is set. And an outdoor expansion valve control means for controlling the opening degree of the outer expansion valve.

[0013] Further, a suction superheat degree detecting means for detecting the superheat degree of the suction refrigerant of the variable capacity compressor, and a chamber for opening the outdoor expansion valve by a predetermined value when the detection value of the suction superheat degree detecting means exceeds a set value. An outer expansion valve protection control means is provided.

[0014]

According to the present invention, when the simultaneous cooling and heating operation is performed by the heating circuit in the refrigeration cycle capable of simultaneous cooling and heating operation, the control state of the indoor unit is not transmitted to the outdoor unit. It is possible to provide an outdoor expansion valve control that can supply a liquid refrigerant to the air conditioner and appropriately control the cooling capacity.

Further, by utilizing the fact that the interior of the receiver provided for the purpose of adjusting the amount of circulating refrigerant in the refrigeration cycle is at the same pressure as the liquid pipe and in a gas-liquid separated state, By indirectly detecting the saturation temperature and controlling the outdoor expansion valve, it can be realized at low cost without using expensive components such as a pressure sensor.

When the cooling load of the indoor unit during the cooling operation is reduced, the timing of opening the outdoor expansion valve is delayed due to the delay of the transient response, and the refrigerant is properly circulated to the suction pipe of the variable speed compressor. In the case where the detection value exceeds the set value, the outdoor expansion valve protection control means for opening the outdoor expansion valve to a predetermined value when the refrigerant superheat degree of the suction pipe of the variable speed compressor is detected even when the exhaust gas is lost. Thus, the variable speed compressor can be protected.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a multi-room air conditioner according to the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a control block diagram of a first embodiment of a multi-room air conditioner according to the present invention. In FIG. 1, 17 is a discharge gas pipe, 18 is a suction gas pipe, and 9 is a liquid pipe. 20a, 20
b is a branch unit, 21a and 21b are discharge side solenoid valves, 2
2a and 22b are intake side solenoid valves. 24 is a liquid pipe pressure detecting means, and 25 is an outdoor expansion valve control means.

The multi-chamber air conditioner of this embodiment comprises an outdoor unit 1 comprising a variable capacity compressor 2, a four-way valve 3, an outdoor expansion valve 5, and an outdoor heat exchanger 4, and an indoor expansion valve 7a, 7b, a plurality of indoor units 6a, 6b with reduced indoor heat exchangers 8a, 8b
And the discharge-side solenoid valves 21a and 21b and the suction-side solenoid valve 22 for switching the flow direction of the refrigerant to the indoor units 6a and 6b.
a, 22b, and the outdoor unit 1 and the plurality of indoor units 6a, 6b are connected to the branch unit 2
0a, 20b, the discharge gas pipe 17, the suction gas pipe 18
And a refrigeration cycle capable of simultaneous cooling and heating operation connected by three pipes of a liquid pipe 9 and a liquid pipe pressure detecting means 24 for detecting the pressure of the liquid pipe 9 and a four-way valve 3 for setting a heating circuit. An outdoor expansion valve control means 25 for controlling a valve opening of the outdoor expansion valve 5 by using a detection value of the liquid pipe pressure detecting means 24 as an input at times.

One end of each of the indoor heat exchangers 8a and 8b is connected to one end of discharge-side solenoid valves 21a and 21b and one end of suction-side solenoid valves 22a and 22b.
7 has one end connected to the discharge side of the variable capacity compressor 2, the other end connected to the other ends of the discharge side solenoid valves 21a and 21b, and the suction gas pipe 18 has one end connected to the suction side of the variable capacity compressor 2. The other end is connected to the suction-side solenoid valves 22a and 22b.
Is connected to the other end.

The four-way valve 3 is used as a three-way valve, and switches the outdoor heat exchanger 4 to communicate with the discharge side or the suction side of the variable capacity compressor 2 by switching. And four-way valve 3
The remaining one end communicates with the suction side of the variable capacity compressor 2 via a capillary tube.

The operation of the multi-room air conditioner configured as described above will be described below with an example in which the indoor unit 6a performs a heating operation and the indoor unit 6b performs a cooling operation. At this time, the setting of each branch unit is as shown in (Table 1).

[0022]

[Table 1]

The flow of the refrigerant is as shown by the arrow in the figure. The liquid refrigerant condensed in the indoor heat exchanger 8a of the indoor unit 6a during the heating operation is divided at the part A, and the room during the cooling operation is operated. This is a refrigeration cycle in which the indoor heat exchanger 8b and the outdoor heat exchanger 4 of the unit 6b evaporate.

Here, if it is assumed that the outdoor expansion valve 5 is opened more than necessary, the pressure of the liquid pipe 9 decreases, the refrigerant is not properly diverted in the portion A, and a large flow to the outdoor heat exchanger 4 is generated. A part of the refrigerant flows, the liquid refrigerant is not supplied to the indoor unit 6b during the cooling operation, and a phenomenon occurs in which the refrigeration cycle maintains a normal operation state without controlling the cooling capacity. Conversely, if it is assumed that the outdoor expansion valve 5 has been throttled more than necessary, the pressure in the liquid pipe 9 will increase, and the indoor unit 6 during the heating operation will increase.
Regardless of the degree of opening of the indoor expansion valve 7a, the degree of supercooling is too high, resulting in a decrease in heating capacity.

That is, in order to appropriately perform the flow division at the portion A, it is necessary to optimally control the opening degrees of the indoor expansion valves and the outdoor expansion valves 5, respectively. However, in order to transmit the opening degree of each indoor expansion valve to the outdoor unit and to recognize the opening degree and control the outdoor expansion valve, an enormous amount of data must be handled, which is irrational.

The first embodiment of the multi-chamber air conditioner according to the present invention comprises a liquid pipe pressure detecting means 24 and an outdoor expansion valve control means 25 for controlling the detected value to the target value by using the detected value as an input. When the liquid pipe pressure increases, the outdoor expansion valve 5 is opened, and when the liquid pipe pressure decreases, the outdoor expansion valve 5 is controlled to be throttled. , The liquid refrigerant can be appropriately divided in the part A without transmitting the liquid refrigerant.

Next, a second embodiment of a multi-room air conditioner according to the present invention will be described with reference to the drawings. Description is omitted. FIG. 2 shows a second embodiment of the multi-room air conditioner according to the present invention.
FIG. 6 is a control block diagram of the embodiment. In FIG.
Is a liquid receiver, which is provided in the middle of the liquid pipe 9 via an introduction pipe. Reference numeral 27 denotes a discharge gas bypass circuit, which is a discharge gas pipe 17.
Is connected to the upper part of the liquid receiver 26 via a capillary tube from the middle of the process. Reference numeral 28 denotes a liquid pipe pressure saturation temperature detecting means.

The operation of the multi-room air conditioner configured as described above will be described below. The liquid refrigerant condensed in the indoor heat exchanger 8a of the indoor unit 6a during the heating operation is stored in the liquid receiver 26 when there is a surplus with respect to the refrigerant circulation amount required by the refrigeration cycle. . At this time, the inside of the liquid receiver 26 has the same pressure as the liquid pipe 9 and is in a gas-liquid separated state, and the temperature at the upper part of the liquid receiver indicates the liquid pipe pressure saturation temperature. The discharge gas bypass circuit 27 prevents the receiver from being full and shows the temperature of the supercooled refrigerant at the upper part of the receiver, and detects the temperature in the discharge gas bypass circuit 27 so that the receiver 26 Since the temperature of the upper part can be substituted, it has a role of facilitating attachment of the temperature sensor. The liquid pipe pressure saturation temperature detecting means 28 detects the temperature in the middle of the discharge gas bypass circuit 27 and transmits the detected value to the outdoor side expansion valve control means 25. By controlling the detection value to a constant value by the outdoor expansion valve control means 25, control equivalent to that of the multi-room air conditioner according to the first embodiment can be performed at lower cost.

Next, a third embodiment of a multi-room air conditioner according to the present invention will be described with reference to the drawings. Description is omitted. FIG. 3 shows a third embodiment of the multi-room air conditioner according to the present invention.
FIG. 6 is a control block diagram of the embodiment. In FIG. 3, 29
Is an outdoor side expansion valve protection control means, 30 is a suction superheat degree detecting means, and the indoor side heat exchanger 8 of the indoor unit 6b during the cooling operation.
It is arranged downstream where b and the refrigerant evaporated by the outdoor heat exchanger 4 merge.

The operation of the multi-room air conditioner configured as described above will be described below. In the first embodiment and the second embodiment, when the cooling load of the indoor unit 6b during the cooling operation is reduced, the indoor expansion valve 7b is throttled,
Since the pressure of the liquid pipe 9 is increased and the outdoor expansion valve 5 is controlled to open, the degree of superheat in the suction pipe of the variable speed compressor 2 is properly maintained. However, when flash gas is generated in the liquid pipe due to a long pipe length, the response time until the pressure of the liquid pipe 9 increases after the indoor expansion valve 7b is throttled is long, and the suction of the variable speed compressor 2 is increased. A phenomenon occurs in which the degree of superheating of the refrigerant in the pipe is too high, and the discharge temperature rises abnormally.

The suction superheat degree detecting means 30 detects the refrigerant superheat degree of the suction pipe of the variable speed compressor 2, and the outdoor expansion valve protection control means 29 determines whether the refrigerant superheat degree exceeds a set value. , The outdoor expansion valve 5 is controlled to open a predetermined value. Even if the pipe length is long and the response time until the pressure of the liquid pipe 9 rises after the indoor expansion valve 7b is throttled is long, the refrigerant superheat degree in the suction pipe of the variable speed compressor 2 is appropriately maintained, The variable speed compressor 2 can be protected.

[0032]

As described above, in the multi-chamber air conditioner of the present invention, the liquid pipe pressure detecting means for detecting the pressure of the liquid pipe, and the four-way valve detecting the value detected by the liquid pipe pressure detecting means when the heating circuit is set. An outdoor expansion valve control unit that controls the valve opening of the outdoor expansion valve as an input, and controls the outdoor expansion valve by using the pressure of the liquid pipe as an input.Therefore, when there is an indoor unit in a cooling operation,
The liquid refrigerant can be supplied to the indoor unit during the cooling operation without transmitting the control state of the indoor unit to the outdoor unit, and the cooling capacity can be controlled.

A receiver for storing the liquid refrigerant in the liquid pipe; a discharge gas bypass circuit for bypassing the discharge gas from the discharge pipe of the variable capacity compressor to the upper part of the receiver via a capillary tube; and a discharge gas bypass circuit. The liquid pipe pressure saturation temperature detecting means that detects the refrigerant temperature in the middle of the process and indirectly detects the pressure saturation temperature of the liquid pipe, and the four-way valve expands outdoor by inputting the detection value of the liquid pipe pressure detecting means when the heating circuit is set. Since the configuration includes the outdoor expansion valve control means for controlling the valve opening degree of the valve, it can be realized at lower cost without using expensive components such as a pressure sensor.

Further, when the detected value of the suction superheat degree detecting means for detecting the degree of superheat of the suction refrigerant of the variable capacity compressor and the detection value of the suction superheat degree detecting means becomes a predetermined value or more, the outdoor expansion valve is opened by a predetermined value. Since the configuration includes the outdoor expansion valve protection control means, when the cooling load of the indoor unit during the cooling operation is reduced, the variable speed compression is performed even in the case of a sudden load change, taking into account the transient response delay. A multi-room air conditioner that can protect the air conditioner can be provided.

[Brief description of the drawings]

FIG. 1 is a control block diagram of a multi-room air conditioner according to a first embodiment of the present invention.

FIG. 2 is a control block diagram of a multi-room air conditioner according to a second embodiment of the present invention.

FIG. 3 is a control block diagram of a multi-room air conditioner according to a third embodiment of the present invention.

FIG. 4 is a control block diagram of a conventional multi-room air conditioner.

[Explanation of symbols]

 Reference Signs List 1 outdoor unit 2 variable capacity compressor 3 four-way valve 4 outdoor heat exchanger 5 outdoor expansion valve 6a, 6b indoor unit 7a, 7b indoor expansion valve 8a, 8b indoor heat exchanger 9 liquid pipe 10 gas pipe 17 discharge Gas pipe 18 Suction gas pipe 20a, 20b Branch unit 21a, 21b Discharge side solenoid valve 22a, 22b Suction side solenoid valve 24 Liquid pipe pressure detecting means 25 Outdoor expansion valve control means 26 Liquid receiver 27 Discharge gas bypass circuit 28 Liquid pipe Pressure saturation temperature detecting means 29 Outdoor expansion valve protection control means 30 Suction superheat degree detecting means

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 29/00 361 F24F 11/02 102 F25B 13/00 104

Claims (3)

(57) [Claims] An outdoor unit comprising a variable capacity compressor, a four-way valve, an outdoor expansion valve, and an outdoor heat exchanger;
A plurality of indoor units including an indoor heat exchanger, a branch unit including a discharge-side solenoid valve and a suction-side solenoid valve for switching a flow direction of refrigerant to each indoor unit, the outdoor unit and the plurality of indoor units. Discharge gas pipe through the branch unit,
A refrigeration cycle capable of simultaneous cooling and heating operation connected by three pipes of a suction gas pipe and a liquid pipe, wherein the liquid pipe pressure detecting means for detecting the pressure of the liquid pipe; A multi-room air conditioner comprising: an outdoor expansion valve control means for controlling a valve opening of the outdoor expansion valve by using a detection value of the liquid pipe pressure detection means as an input at the time of setting. 2. An outdoor unit comprising a variable capacity compressor, a four-way valve, an outdoor expansion valve, and an outdoor heat exchanger;
A plurality of indoor units including an indoor heat exchanger, a branch unit including a discharge-side solenoid valve and a suction-side solenoid valve for switching a flow direction of refrigerant to each indoor unit, the outdoor unit and the plurality of indoor units. Discharge gas pipe through the branch unit,
A receiver having a refrigeration cycle connected by three pipes, a suction gas pipe and a liquid pipe, capable of simultaneous operation of cooling and heating, and receiving a liquid refrigerant in the liquid pipe; and a discharge pipe of the variable capacity compressor A discharge gas bypass circuit for bypassing a discharge gas to the upper part of the receiver via a capillary tube, and a liquid pipe for detecting a refrigerant temperature in the middle of the discharge gas bypass circuit and indirectly detecting a pressure saturation temperature of the liquid pipe. A pressure saturation temperature detection means, and an outdoor expansion valve control means for controlling the valve opening degree of the outdoor expansion valve by inputting a detection value of the liquid pipe pressure saturation temperature detection means when the four-way valve sets a heating circuit. Multi-room air conditioner. 3. A suction superheat degree detecting means for detecting a superheat degree of a suction refrigerant of the variable capacity compressor, and when the detection value of the suction superheat degree detection means becomes a predetermined value or more, the outdoor expansion valve is set to a predetermined value. The multi-room air conditioner according to claim 1, further comprising an outdoor expansion valve protection control means that opens.