JP2001241799A - Multi-room air conditioner - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a multi-chamber air conditioner, for example, when one chamber stops operating, the variable capacity type compressor follows the speed at which the operating frequency decreases and the throttle amount control of the electric expansion valve. By doing so, it is possible to prevent a rapid rise in the high pressure side pressure. A plurality of indoor units (2, 3) are connected to an outdoor unit (1), and a variable capacity compressor (4), a four-way valve (5), an outdoor heat exchanger (6),
A plurality of indoor heat exchangers 9a, 9b, a plurality of electric expansion valves 7
a and 7b constitute a refrigeration cycle, and when the operation frequency of the variable capacity compressor 4 is changed in accordance with a load change of the indoor units 2 and 3, the electric expansion valve 7 corresponding to the operation frequency is changed.
a, 7b, the plurality of electric expansion valves 7
The speed when closing a and 7b is set to be lower than the speed when opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-room air conditioner, and more particularly, to a throttling control of a refrigeration cycle for the purpose of protecting the refrigeration cycle from abnormal increase such as a sudden increase in high pressure in a transient state of the refrigeration cycle. .

[0002]

2. Description of the Related Art In a multi-room air conditioner in which a plurality of outdoor units are connected to one outdoor unit, a refrigeration cycle is provided with a variable capacity compressor and an electric expansion valve. A technique related to the throttle control of the electric expansion valve in a transient state at the time is disclosed, for example, in Japanese Patent Application Laid-Open No. 6-74590.

According to this, an outdoor unit provided with a variable capacity compressor, a four-way valve, an outdoor heat exchanger, and an outdoor electric expansion valve, and the outdoor unit provided with an indoor outdoor electric expansion valve and an indoor heat exchanger. It consists of an indoor unit with multiple units connected in parallel to the unit,
Further, a superheat degree detecting means for detecting the degree of superheat of the indoor heat exchanger and a temperature setting means for setting a target temperature are provided, and protection control is performed when all of the superheat degrees detected by the superheat degree detecting means are equal to or more than a predetermined value. Therefore, the control for uniformly closing the opening of each of the electric expansion valves is performed in distinction from the normal throttle control of the electric expansion valves.

[0004]

However, in the above-described multi-room air conditioner having the control configuration according to the prior art, for example, when one of the two indoor units is stopped when the two indoor units are in operation, the capacity is increased. In the deformed compressor, the throttle operation of the electric expansion valve occurs at the same time as the operating frequency is halved, but when the operating frequency is reduced to the required capacity, the throttle amount of the electric expansion valve changes faster than the operating frequency decreases, Since the protection control by the superheat control causes a considerable time lag, there is a problem that the high pressure side pressure rises rapidly because it cannot follow the restriction amount control that matches the required capacity, and the life and reliability of the compressor are impaired. .

[0005] In order to solve such a problem, the present invention relates to throttle control of an electric expansion valve for adjusting a change speed of an operating frequency of a compressor and a flow rate of refrigerant to each indoor unit. The purpose is to improve the life and reliability and the comfort in actual use.

[0006]

According to the first aspect of the present invention, there is provided an outdoor unit and a plurality of indoor units, an inverter-driven variable capacity compressor, a four-way valve for switching a refrigerant flow, An outdoor heat exchanger, a plurality of indoor heat exchangers, a refrigeration cycle with a plurality of electric expansion valves capable of varying the throttle amount, and the electric expansion valves are provided in one-to-one correspondence with the plurality of indoor heat exchangers. When changing the operation frequency of the variable capacity compressor due to the load fluctuation of the indoor unit, when controlling the flow rate of the electric expansion valve corresponding to the operation frequency, when opening the speed of closing the electric expansion valve, It is designed to be slower than the speed.

[0007] With this configuration, it is possible to suppress a rapid increase in high pressure in the refrigeration cycle and improve the reliability such as the life of the compressor.

Further, according to the present invention, when the operating frequency of the variable capacity compressor is increased due to the load fluctuation of the indoor unit, the speed at which the electric expansion valve is opened is set higher than the operating frequency. When the operating frequency decreases rapidly, the electric expansion valve is closed at a speed equal to or lower than the decrease in the operating frequency.

With this configuration, in a transient state in which the operating frequency of the compressor suddenly decreases, the speed at which the electric expansion valve throttles to the target throttle amount becomes slower than that when the operating frequency decreases to the target frequency, and the pressure drops sharply. Therefore, dew condensation due to freezing of the indoor heat exchanger and disruption of the path balance can be prevented.

Further, the invention according to claim 3 provides a refrigerant for the indoor unit which determines that the indoor temperature has reached the indoor set temperature during the cooling operation, or determines that the cooling operation does not need to be continued by a stop command from a remote controller or the like. When the flow is stopped and the operating frequency of the variable capacity compressor is decreased, the electric expansion valve is closed at a speed higher than the decreasing speed of the operating frequency.

With this configuration, it is possible to prevent dew condensation on the stopped indoor unit in the transient state.

Further, according to the present invention, the refrigerant to the indoor unit which determines that the indoor temperature has reached the indoor set temperature during the heating operation, or determines that the heating operation is not required to be continued by a stop command from a remote controller or the like. When the operating frequency of the variable capacity compressor is reduced while reducing the flow to a very small amount, the electric expansion valve is closed with a predetermined minute opening degree faster than the decreasing speed of the operating frequency. It is.

With this configuration, it is possible to mitigate a sudden drop in the temperature of the blown air from the stopped indoor unit in the transient state, and to improve comfort in actual use.

[0014]

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

In FIG. 1, the multi-room air conditioner according to the present embodiment is configured by connecting an outdoor unit 1 and two indoor units 2 and 3.

The outdoor unit 1 has a variable displacement compressor 4 driven by an inverter, a four-way valve 5 for switching the flow of refrigerant, an outdoor heat exchanger 6, and an electric expansion valve 7a driven by a pulse signal.
The indoor unit 2 has an indoor heat exchanger 8a and an indoor temperature sensor 9a composed of a thermistor for detecting the indoor temperature. The indoor unit 3 has an indoor heat exchanger 8b and a thermistor for detecting the indoor temperature. , And these components are sequentially connected to form a refrigeration cycle.

As shown in FIG. 2, the multi-room air conditioner having the above-described structure has an indoor temperature sensor 9a provided in the indoor units 2 and 3.
Temperature input values Ta, tb from the room temperature setting detecting means 10a, 10b for detecting temperature input values ta, tb from the room 9b and a room set temperature set by a remote controller (not shown).
Compared with Tb indoor units 2 and 3, deviations ΔTa (= Ta−ta) and Δba (= Tb−tb) of the respective temperature input values.
The required capacity of each of the indoor units 2 and 3 is determined according to the size of the signal, and the signal analysis means 12a and 12b for sending the signals Qa and Qb to the calculation means 11 of the outdoor unit 1 and the operation mode (cooling, heating, etc.) set by a remote controller or the like. Mode determination means 1 for determining)
3a, 13b are provided in the indoor units 2, 3.

The operating means 11 calculates the operating frequency of the compressor 4 from the signals Qa and Qb, issues an instruction of the required operating frequency to the compressor operating means 14, and sends the signals Qa and Qb to the electric expansion valves 7a and 7b. An optimum refrigeration cycle is formed by instructing the expansion valves driving means 15a and 15b on the required flow rates Ra and Rb calculated from Qb. The expansion valve driving means 15a and 15b are electrically operated expansion valves 7a and 15b.
The opening speed and the closing speed of the opening 7b can be freely changed, and the opening speed is normally lower than the closing speed in normal times.

Next, a specific operation will be described.

The multi-room air conditioner according to the present embodiment enables two indoor units 2 and 3 to operate simultaneously or one unit to operate independently.

In the cooling operation, the refrigerant is supplied to the compressor 4,
A refrigeration cycle is formed that circulates through the four-way valve 5, the outdoor heat exchanger 6, the electric expansion valves 7a and 7b, and the indoor heat exchangers 8a and 8b and returns to the compressor 4 through the four-way valve 5 again to perform the cooling operation. Will be implemented.

During the simultaneous cooling operation of the two indoor units 2 and 3,
For example, the indoor temperature sensor 9a of the indoor unit 2 detects the room temperature ta, and the deviation ΔTa (= ta−Ta) from the set temperature Ta detected by the indoor set temperature detection unit 10a is larger than the previous time, and Signal analysis means 12 should increase capacity
a, 12b determine, the signal Q2 for increasing the operating frequency of the compressor 4 is transmitted to the calculating means 11, and if the signal Q3 indicating the continuation of the operating capacity is transmitted from the indoor unit 3 to the calculating means 11, the calculating means 11 From Q2 and Q3, the required increase in the operating frequency of the compressor 4 and the optimum increase in the opening of the electric expansion valve 7a are transmitted to the expansion valve driving means 15a.

The expansion valve driving means 15a extends the opening of the electric expansion valve 7a to the target opening until the compressor operating frequency reaches the target operating frequency.

As a result, it is possible to suppress a rapid increase in the high pressure of the refrigeration cycle in an overload transient state where the outside air temperature is high, and to improve the reliability such as the life of the compressor.

Conversely, when the capacity of the indoor unit 2 is reduced, the expansion valve driving means 15a controls the electric expansion at the same time as the compressor operating frequency reaches the target operating frequency or later. The opening of the valve 7a is closed to a target value.

As a result, in a transient state in which the operating frequency of the compressor 4 suddenly decreases, the speed at which the electric expansion valve 7a throttles down to the target throttle amount becomes slower than that when the operating frequency decreases to the target frequency, and the pressure increases rapidly. Since no drop occurs, dew condensation due to freezing of the indoor heat exchanger 8a or disruption of the path balance can be prevented.

A stop command of the indoor unit 2 by a remote controller or the like is detected by the operation mode determining means 13a and transmitted to the signal analyzing means 12a, or the temperature data Ta from the indoor temperature sensor 9a and the room temperature set temperature detecting means. The temperature data ta from 10a is compared by the signal analysis means 12a, and if it is determined that the cooling operation of the indoor unit needs to be stopped, the arithmetic means 11 determines the compressor based on the remaining capacity required by the indoor unit 3 4 is transmitted to the compressor operating means 14 and the full-closed state is immediately transmitted to the expansion valve driving means 15a. The expansion valve driving means 15a operates the instant expansion valve 7a regardless of the changing speed of the compressor operating frequency. Is fully closed.

As a result, the stopped indoor unit 2 in the transient state
Dew condensation can be prevented.

During the heating operation, the refrigerant is supplied to the compressor 4, the four-way valve 5, the indoor heat exchangers 8a and 8b, and the electric expansion valve 7.
a, 7b, circulating with the outdoor heat exchanger 6 and again
, A refrigeration cycle returning to the compressor 4 is formed, and the heating operation is performed.

During the simultaneous heating operation of the two indoor units 2 and 3,
For example, the indoor temperature sensor 9a of the indoor unit 2 detects the room temperature tah, and the deviation ΔTah (= Tah−tah) from the set temperature Tah detected by the indoor set temperature detecting unit 10a is larger than the previous time, The signal analyzing means 12a and 12b determine that the capacity should be increased, and a signal Q2h for increasing the operating frequency of the compressor 4 is transmitted to the calculating means 11, and a signal Q3h indicating the continuation of the operating capacity is transmitted from the indoor unit 3 to the calculating means 11. In this case, the calculating means 11 determines from the signals Q2h and Q3h the increase in the required operating frequency of the compressor 4 and the optimum increase in the opening of the electric expansion valve 7a.
to a.

The expansion valve driving means 15a extends the opening of the electric expansion valve 7a to the target opening until the compressor operating frequency reaches the target operating frequency.

As a result, it is possible to suppress a rapid increase in the high pressure of the refrigeration cycle in the transient state, and to improve the reliability such as the life of the compressor.

A stop command of the indoor unit 2 by a remote controller or the like is detected by the operation mode determining means 13a and transmitted to the signal analyzing means 12a, or the temperature data tah from the indoor temperature sensor 9a and the detected room temperature set temperature are detected. Means 10a
Is compared by the signal analysis means 12a, and if it is determined that the heating operation of the indoor unit needs to be stopped, the calculating means 11 determines the required capacity of the remaining indoor unit 3 and the indoor unit In order to prevent accumulation of the refrigerant liquid in the compressor 2, the operating frequency of the compressor 4 added with the capacity necessary for circulating a very small amount of refrigerant is transmitted to the compressor operating means 14, and the expansion valve driving means is also provided. An instruction is issued to 15a to immediately close the electric expansion valve 7a with only a small amount of opening left, regardless of the change speed of the compressor operating frequency.

As a result, a sudden decrease in the temperature of the air blown from the indoor unit 2 is alleviated, and the comfort in actual use can be improved.

Each control described above is realized by a microcomputer mounted on the multi-room air conditioner and its program software.

The same effect can be obtained in the indoor units 2 and 3 where the electric expansion valves 7a and 7b are installed.

In this embodiment, two indoor units have been described. However, in the case of three or more indoor units, it is needless to say that the same concept as described above can be applied.

[0038]

The present invention is embodied in the form described above, and has the following effects.

The invention according to claim 1 comprises one outdoor unit and a plurality of indoor units, an inverter-driven variable capacity compressor, a four-way valve for switching the flow of refrigerant, an outdoor heat exchanger, and a plurality of indoor heat exchangers. An exchanger has a refrigeration cycle with a plurality of electric expansion valves capable of changing the throttle amount, and the electric expansion valves are provided in one-to-one correspondence with a plurality of the indoor heat exchangers, and are associated with load fluctuations of the indoor unit. At the time of changing the operating frequency of the variable capacity compressor, as the flow control of the electric expansion valve corresponding to the operating frequency, the speed when closing the electric expansion valve is set to be lower than the speed when opening the electric expansion valve. Therefore, the rapid increase in high pressure of the refrigeration cycle can be suppressed, and the reliability such as the life of the compressor can be improved.

According to a second aspect of the present invention, when the operating frequency of the variable capacity compressor increases due to the load fluctuation of the indoor unit,
As compared with the increase in the operation frequency, the speed at which the electric expansion valve is opened is faster, and when the operation frequency is decreased, the electric expansion valve is closed at a speed equal to or lower than the decrease in the operation frequency. Therefore, in a transient state in which the operating frequency of the compressor 4 suddenly decreases, the speed at which the electric expansion valve 7a throttles to the target throttle amount becomes slower than that when the operating frequency decreases to the target frequency, and a sharp pressure drop occurs. Therefore, dew condensation due to freezing of the indoor heat exchanger and collapse of the path balance of the indoor heat exchanger can be prevented.

According to the third aspect of the present invention, the refrigerant circulation to the indoor unit that determines that the indoor temperature has reached the indoor set temperature during the cooling operation or that it is determined that the cooling operation does not need to be continued by a stop command from a remote controller or the like. When stopping and lowering the operating frequency of the variable capacity compressor, the electric expansion valve is closed at a speed higher than the decreasing speed of the operating frequency, so that dew condensation on the stopped indoor unit 2 in a transient state is prevented. it can.

According to a fourth aspect of the present invention, the refrigerant circulation to the indoor unit which determines that the indoor temperature has reached the indoor set temperature during the heating operation or determines that the heating operation need not be continued by a stop command from a remote controller or the like is determined. When the operating frequency of the variable capacity compressor is reduced to a very small amount, the motor-operated expansion valve is closed with a predetermined small opening degree faster than the decreasing speed of the operating frequency when lowering the operating frequency. In this state, the sudden drop in the temperature of the blowout air from the stopped indoor unit is alleviated,
Comfort in actual use can be improved.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram of a multi-room air conditioner according to an embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outdoor unit 2, 3 Indoor unit 4 Compressor 5 Four-way valve 6 Outdoor heat exchanger 7a, 7b Electric expansion valve 8a, 8b Indoor heat exchanger 9a, 9b Indoor temperature sensor 10a, 10b Indoor temperature detecting means 11 Computing means 12a 12b Signal analysis means 13a, 13b Operation mode determination means 14 Compressor operation means 15a, 15b Expansion valve drive means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F25B 5/02 520 F25B 5/02 520A F-term (Reference) 3L060 AA05 CC02 DD02 DD03 EE04 EE09 3L092 AA03 AA12 BA13 BA23 DA15 EA11 FA27 GA04 HA12 JA05 JA11 KA10 LA06

Claims (4)

[Claims] 1. An outdoor unit and a plurality of indoor units, an inverter-driven variable capacity compressor, a four-way valve for switching refrigerant flow, an outdoor heat exchanger, a plurality of indoor heat exchangers, and a throttle amount. A refrigeration cycle including a plurality of variable electric expansion valves, wherein the electric expansion valves are provided in one-to-one correspondence with a plurality of the indoor heat exchangers, and the variable capacity compressor accompanying a load change of the indoor unit is provided. In the operation of changing the operating frequency of the multi-chamber type, as the flow rate control of the electric expansion valve corresponding to the operating frequency, the speed at which the electric expansion valve is closed is controlled to be lower than the speed at the time of opening. Air conditioner. 2. When the operating frequency of a variable capacity compressor increases due to a load change in an indoor unit, the speed at which the electric expansion valve opens increases faster than the operating frequency increases, and the operating frequency decreases. 2. The multi-room air conditioner according to claim 1, wherein, at the time, the electric expansion valve is controlled to close at a speed equal to or lower than the operating frequency. 3. During cooling operation, the refrigerant flow to the indoor unit, which determines that the indoor temperature has reached the indoor set temperature, or determines that the cooling operation does not need to be continued by a stop command from a remote controller or the like, and stops the cooling operation. 2. The multi-chamber air conditioner according to claim 1, wherein when the operating frequency of the variable compressor is decreased, control is performed such that the electric expansion valve is closed faster than the decreasing speed of the operating frequency. 4. A refrigerant flow to an indoor unit, which determines that the indoor temperature has reached the indoor set temperature during the heating operation or determines that the heating operation does not need to be continued by a stop command from a remote controller or the like, is reduced to a very small amount. 2. The method according to claim 1, wherein when the operating frequency of the variable capacity compressor is decreased, the motor-operated expansion valve is controlled so as to be closed with a predetermined small opening degree faster than a decreasing speed of the operating frequency. Multi-room air conditioner.