JPH03251664A - Multiroom-type air-conditioner - Google Patents

Abstract

PURPOSE:To improve a rise property and to increase comfortableness by a method wherein the capacity control of a capacity-variable compressor is conducted, through an inverter, on the basis of a pressure detected by a pressure sensor from the time point when the degree of excessive cooling of a refrigerant detected at the time of a cooling rise operation becomes a prescribed degree of excessive cooling or above. CONSTITUTION:At the time when a cooling operation is started, the degree of excessive cooling of a refrigerant at the outlet of an outdoor-side heat exchanger 4 is detected by a detector 13. From the time point when this degree of excessive cooling of the refrigerant becomes a prescribed degree of excessive cooling or above, the capacity of a variable capacity compressor 2 is controlled by an outdoor-unit controlling means 15 through an inverter 12 on the basis of a pressure detected by a pressure sensor 11. Thereby comfortableness at the rise time is increased and a fault of the compressor 2 due to a shortage of the quantity of the refrigerant in circulation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multi-room air conditioner, and particularly to a structure for preventing failures when starting with stale refrigerant.

BACKGROUND OF THE INVENTION In recent years, individual air conditioning has been progressing in building air conditioning, and as known from Japanese Patent Application Laid-Open No. 1-212870, individual control of multi-room air conditioners has been progressing.

The conventional technology will be described below with reference to the drawings.

In FIG. 4, 1 is an outdoor unit of a multi-room air conditioner, and 2 is a variable capacity compressor. Four-way valve 3. Outdoor heat exchanger4. An outdoor electric expansion valve 5 and an outdoor fan 6 are installed. 7 are indoor units, four of which are connected in parallel to the outdoor unit 1, each with an indoor electric expansion valve 8. An indoor heat exchanger 9 and an indoor fan 10 are installed.

Reference numeral 11 denotes a pressure sensor, which is installed in the pipe inside the outdoor unit between the four-way valve 3 and the indoor heat exchanger 9.

An inverter 12 controls the frequency of the variable capacity compressor 7 based on the pressure detected by the pressure sensor 11.

The operation of the multi-room air conditioner configured as above will be explained.

First, in cooling operation, the high temperature and high pressure refrigerant discharged from the variable capacity compressor 2 passes through the four-way valve 3, flows into the outdoor heat exchanger 4, condenses and liquefies, and passes through the outdoor electric expansion valve 5. The air is distributed to the indoor unit 7 by piping, is depressurized by the indoor electric expansion valve 8, is evaporated in the outdoor heat exchanger 9, and returns to the variable capacity compressor 2 via the four-way valve 3 again. Further, during heating operation, the high temperature and high pressure refrigerant discharged from the variable capacity compressor 2 is distributed to each indoor unit via the four-way valve 3. The refrigerant is condensed and liquefied in the indoor heat exchanger 9 , passed through the indoor electric expansion valve 8 , reduced in pressure by the outdoor electric expansion valve 5 , evaporated in the outdoor heat exchanger 4 , and liquefied through the four-way valve 3 . variable capacity compressor 2
Return to

At this time, the capacity of the variable capacity compressor 2 is determined by the pressure sensor 11.
However, the inverter 12 adjusts the frequency of the variable capacity compressor 2 to a predetermined pressure based on the detected pressure (evaporation pressure during cooling, condensation pressure during heating) that changes depending on the air conditioning load at that time. This is done by increasing or decreasing.

Problems to be Solved by the Invention However, in the above configuration, the capacity of the variable capacity compressor 2 is controlled by the refrigerant pressure, so when starting up after a long stop, especially during cooling operation, the refrigerant may run out at the beginning of starting up. When the refrigerant accumulates in each element in the cycle, sufficient refrigerant circulation cannot be obtained, and the suction pressure decreases. During the reverse response, the compression function force control lowers the inverter frequency, and furthermore, the refrigerant circulation becomes insufficient. There was a problem that the capacity was extremely insufficient because the cycle could not be completed, the degree of superheating of the refrigerant sucked into the compressor increased, and the motor burned out due to the excessive rise in compressor temperature.

Therefore, the present invention solves the above-mentioned conventional problems. By detecting the insufficient amount of refrigerant circulation at the initial stage of startup and speeding up the start-up operation by controlling the suction pressure, the present invention improves comfort during start-up and further improves the amount of refrigerant circulation. This prevents compressor failure due to shortage.

Means for Solving the Problem In order to solve this problem, the multi-room air conditioner of the present invention includes an outdoor unit equipped with a variable capacity compressor, a four-way valve, an outdoor heat exchanger, and an outdoor electric expansion valve. , an indoor unit including an indoor electric expansion valve and an indoor heat exchanger and connected in parallel to the outdoor unit; an outdoor unit control means for controlling the operation of the outdoor unit; and the four-way valve. a pressure sensor in piping between the indoor unit and the indoor unit, an inverter that is controlled by the outdoor unit control means to control the frequency of the variable capacity compressor, and piping that connects the outdoor heat exchanger and the outdoor electric expansion valve. The outdoor unit control means detects the degree of subcooling of the refrigerant from the point at which the degree of subcooling of the refrigerant detected by the refrigerant subcooling detector becomes equal to or higher than a predetermined degree of subcooling during startup operation of the air conditioner. The compressor is configured to control the capacity of the variable capacity compressor via the inverter based on the detected pressure.

Operation The multi-room air conditioner of the present invention has the above-described configuration, detects the degree of subcooling of the refrigerant at the outlet of the outdoor heat exchanger at the start of cooling operation, detects the reverse response of the cycle, and during that time, performs variable compression compression. By detecting the end of the reverse response and starting capacity control without controlling the machine's capacity, it increases comfort during start-up and prevents compressor failure due to insufficient refrigerant circulation. .

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS.
Reference numeral 13, which will not be described in detail, is a refrigerant subcooling degree detector, which is installed in the refrigerant pipe between the outdoor heat exchanger 4 and the outdoor electric expansion valve 5. Reference numeral 14 denotes an indoor unit control means installed in each indoor unit, which can be operated to start/stop the indoor unit 7, cool the air conditioner, etc.
Heating switching, indoor electric expansion valve 8, indoor fan 10
control and communicate with the outdoor unit. Reference numeral 15 denotes an outdoor unit control means, which operates the outdoor unit 1 and controls the inverter 12, four-way valve 8, outdoor electric expansion valve 5, and outdoor fan 6 based on communication from each indoor unit control means 14.

Next, the operation of the above configuration will be explained.

The variable capacity compressor 2 is started at a predetermined starting frequency by the inverter 12 in response to a command from the outdoor unit control means 15. When the variable capacity compressor 2 is started, refrigerant begins to circulate within the cycle, but since the refrigerant remains in each element in the cycle, the discharge pressure of the variable capacity compressor 2 does not rise sufficiently, and the condenser In some outdoor heat exchangers 4, sufficient condensing capacity cannot be obtained, and the refrigerant state here is an extremely small supercooled state or a two-phase state (saturated state). At this time, the refrigerant supercooling degree detector 13 detects this state and controls the outdoor unit control means 15.
to communicate. The outdoor unit control means 15 determines from this information that the reverse response state continues, ignores the detected pressure from the pressure sensor 11, and continues operation at the starting frequency.

By continuing to operate the variable capacity compressor 2 at the starting frequency, the refrigerant stagnant in each element in the cycle gradually begins to circulate throughout the cycle, the cycle starts operating normally, and the condensing pressure rises. However, the condensing capacity of the outdoor heat exchanger 4 increases, and the refrigerant at the refrigerant outlet becomes a supercooled refrigerant.

At this time, the refrigerant subcooling degree detector 13 detects the subcooling degree of the refrigerant, and the outdoor unit control means 15 terminates the reverse response of the cycle when the detected refrigerant subcooling degree becomes equal to or higher than a predetermined subcooling degree. is detected, and the operating frequency is increased or decreased based on the difference between the pressure detected by the pressure sensor 11 and the target pressure, and capacity control of the variable capacity compressor 2 is started.

In this way, even though the air conditioning cycle does not have sufficient capacity, due to the decrease in suction pressure, the capacity of the variable capacity compressor 2 is reduced by suction pressure control. Avoid shortages.

Effects of the Invention As is clear from the above explanation, the multi-room air conditioner according to the present invention has an outdoor unit equipped with a variable capacity compressor, a four-way valve, an outdoor heat exchanger, an outdoor electric expansion valve, and an indoor unit. an indoor unit installed with an inner electric expansion valve and an indoor heat exchanger and connected to the outdoor unit in a plurality of rows; an outdoor unit control means for controlling the operation of the outdoor unit in the outdoor unit; and the four-way valve. A pressure sensor is installed in a pipe between the indoor units, an inverter that is controlled by the outdoor unit control means and controls the frequency of the variable capacity compressor, and a pipe that connects the outdoor heat exchanger and the outdoor electric expansion valve. The outdoor unit control means includes an installed refrigerant subcooling degree detector, and the outdoor unit control means controls the pressure sensor from the time when the degree of subcooling of the refrigerant detected by the refrigerant subcooling detector becomes equal to or higher than a predetermined degree of subcooling during startup operation of the air conditioner. Since the capacity of the variable capacity compressor is controlled via the inverter based on the detected pressure, it is possible to avoid problems such as a reverse response phenomenon during cooling start-up, prolonged start-up operation, insufficient capacity, or excessive superheating of the suction refrigerant. It prevents burnout of the compressor motor, improves comfort by improving start-up performance, and has great effects on reliability.

Note that the present invention applies not only to multi-room air conditioners but also to ordinary air conditioners with one indoor unit and one outdoor unit, as long as they are equipped with a pressure sensor and a refrigerant subcooling degree detector.
Similar configurations can be used and similar effects can be achieved.

[Brief explanation of drawings]

Fig. 1 is a refrigeration cycle diagram of a multi-room air conditioner which is an embodiment of the present invention, Fig. 2 is a block diagram of the control circuit of the multi-room air conditioner of Fig. 1, and Fig. 3 is a block diagram of the control circuit of the multi-room air conditioner of Fig. FIG. 4 is a flowchart of the control of the multi-room air conditioner, and FIG. 4 is a refrigeration cycle diagram of the conventional multi-room air conditioner.・Outdoor unit, 2... variable capacity compressor, four-way valve, 4... outdoor heat exchanger, outdoor electric expansion valve, 7... indoor unit, indoor electric expansion valve, 9... indoor Inner heat exchanger 1...Pressure sensor 12...In 13...Refrigerant supercooling degree detector, 1 Indoor unit control means, 15...Outdoor unit control 3 ・ ・ ・ 5 ・ ・ ・ 8 ・ ・ ・exchanger, 1 park, 4... means.

Claims (1)

[Claims] An outdoor unit is installed with a variable capacity compressor, a four-way valve, an outdoor heat exchanger, and an outdoor electric expansion valve, and an indoor electric expansion valve and an indoor heat exchanger are installed, and multiple units are connected in parallel to the outdoor unit. an indoor unit, an outdoor unit control means for controlling the operation of the outdoor unit, a pressure sensor in piping between the four-way valve and the indoor unit, and a variable capacity compressor controlled by the outdoor unit control means. and a refrigerant supercooling degree detector installed in a pipe connecting the outdoor heat exchanger and the outdoor electric expansion valve. A multi-chamber air compressor that controls the capacity of the variable capacity compressor via the inverter based on the pressure detected by the pressure sensor from the time when the degree of subcooling of the refrigerant detected by the cooling detector becomes equal to or higher than a predetermined degree of subcooling. harmonizer.