JP2005140431A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve comfortableness in an air conditioner comprising one outdoor unit and a plurality of indoor units connected thereto by sufficiently bringing out the heating capability of an operating-side indoor unit even at the time of low rotation of a compressor. <P>SOLUTION: This air conditioner comprises the plurality of indoor units and the outdoor unit connecting the indoor units in parallel. The outdoor unit comprises an electric expansion valve for independently controlling refrigerant flow rate to the indoor units, a temperature sensor for detecting a supercooling refrigerant temperature, and an electric expansion valve control means for controlling the opening of the electric expansion valve so that an operating-side supercooling refrigerant temperature and a stopping-side supercooling refrigerant temperature have a predetermined temperature difference computed from the rotating speed of the compressor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an air conditioner, and is particularly suitable for an air conditioner in which a plurality of indoor units are connected in parallel to one outdoor unit.

  In such an air conditioner, in recent years, an inexpensive refrigerant circuit in which an electric expansion valve associated with each indoor unit is provided only on a small-diameter pipe side, and an electromagnetic valve or an electric expansion valve is deleted from the large-diameter pipe side. The number of air conditioning is increasing.

  An example of such an air conditioner will be described with reference to FIG. In this example, two indoor units A and B are connected to one outdoor unit C.

  As shown in FIG. 5, the two indoor units A and B are connected to the outdoor unit C by the large-diameter pipes 10a and 10b and the small-diameter pipes 11a and 11b, and the indoor heat exchanger 4a, 4b and indoor fans 5a and 5b. On the other hand, the outdoor unit C is provided with a compressor 1, a four-way valve 2, an outdoor heat exchanger 8, and an outdoor fan 9. The small-diameter pipes 11a and 11b in the outdoor unit C are provided with electric expansion valves 7a and 7b corresponding to the indoor units A and B, respectively. Note that the refrigerant flows in the direction of the solid arrow during the heating operation.

  In such an air conditioner, when heating the indoor units A and B simultaneously, the electric expansion valve 7a on the indoor unit A side and the electric expansion valve 7b on the indoor unit B side are individually controlled according to the air conditioning load. By distributing an appropriate amount of refrigerant to the indoor heat exchangers 4a and 4b of the indoor units A and B, the refrigerant circuit can be operated efficiently.

  When the heating operation is performed only on the indoor unit A side and the indoor unit B side is stopped, when the electric expansion valve 7b on the indoor unit B side is fully closed, the indoor heat exchanger 4b of the indoor unit B and the small diameter pipe Since the condensed refrigerant stays in 11b and the heating capacity is reduced due to insufficient refrigerant circulation in the entire refrigerant circuit, the electric expansion valve 7b in the small-diameter pipe 11b on the stop side is opened at a predetermined opening, Restraining is prevented by controlling the flow.

  Specifically, refrigerant temperature sensors 23a and 23b for detecting the refrigerant temperature are provided in the small-diameter pipes 11a and 11b on the indoor units A and B side of the electric expansion valves 7a and 7b. A predetermined opening degree of each of the electric expansion valves 7a and 7b is detected so that the cooling refrigerant temperature and the subcooling refrigerant temperature on the stop side are detected and the subcooling refrigerant temperature on the operation side and the subcooling refrigerant temperature on the stop side have a predetermined temperature difference. Is controlled to prevent the refrigerant from staying in the indoor heat exchanger 4b and the small-diameter pipe 11b on the stop side.

  Further, when the outside air temperature is low by controlling each of the electric expansion valves 7a and 7b so that the subcooling refrigerant temperature on the operation side and the subcooling refrigerant temperature on the stop side have a predetermined temperature difference calculated from the outside air temperature. Retention of refrigerant in the indoor heat exchanger 4b on the stop side and the small diameter connecting pipe 11b is prevented.

  Japanese Patent Application No. 2002-056717 (Patent Document 1) can be cited as a related art.

Japanese Patent Application No. 2002-056717

  In such a conventional air conditioner, the heating operation is performed only on the indoor unit A side, and the indoor unit B side is stopped. The air conditioning load is small, and the compressor 1 is operated at a low rotation speed to reduce the refrigerant circulation amount. In this state, the temperature of the indoor heat exchangers 4a and 4b is lower than that at the time of high rotation, whereas the supercooling refrigerant temperature does not drop much. For this reason, the difference between the temperature of the supercooling refrigerant on the operation side and the temperature of the supercooling refrigerant on the stop side is not so large, and if the control is performed with the same temperature difference as when the refrigerant circulation amount is large, It was found that the flow rate of the valve 7a was controlled to be extremely small, and conversely, the refrigerant circulation amount to the indoor heat exchanger 4a on the operation side was insufficient.

  The objective of this invention is providing the air conditioner which can fully draw out the heating capability of the indoor unit by the side of a driving | operation, and can improve comfort also at the time of the low rotation of a compressor.

  In order to achieve the object, the present invention includes a plurality of indoor units that can be individually operated and stopped, and an outdoor unit that connects the plurality of indoor units in parallel, and the outdoor unit compresses a refrigerant. A compressor, a small-diameter pipe connection valve and a large-diameter pipe connection valve that connect pipes of each of the indoor units, an electric expansion valve that individually controls a refrigerant flow rate for the plurality of indoor units, and the electric expansion valve And a supercooling refrigerant temperature sensor for detecting a supercooling refrigerant temperature sensor between the small-diameter pipe connection valve and the supercooling refrigerant temperature sensor at the operation side during heating operation. Detecting the temperature and the subcooling refrigerant temperature on the stop side, respectively, so that the supercooling refrigerant temperature on the operation side and the subcooling refrigerant temperature on the stop side have a predetermined temperature difference calculated from the rotational speed of the compressor Electricity that controls the opening of the electric expansion valve In that a configuration with an inflation valve control means.

  In the present invention, preferably, the apparatus includes a refrigerant discharge temperature sensor for detecting the temperature of the refrigerant discharged from the compressor and an outside air temperature sensor for detecting the outside air temperature, and the electric expansion valve control means includes the refrigerant The refrigerant discharge temperature detected by the discharge temperature sensor, the actual compressor rotation speed detected by the compressor rotation speed detection means, the supercooling refrigerant temperature detected by the supercooling refrigerant temperature sensor, and the outside air temperature detected by the outside air temperature sensor Based on this, the valve opening degree of the electric expansion valve is controlled.

  In the above invention, the preferred electric expansion valve control means includes a refrigerant discharge temperature sensor for detecting the temperature of the refrigerant discharged from the compressor and an outside air temperature sensor for detecting the outside air temperature, and the electric expansion valve control means. Is detected by the refrigerant discharge temperature detected by the refrigerant discharge temperature sensor, the actual compressor rotation speed detected by the compressor rotation speed detection means, the supercooling refrigerant temperature detected by the supercooling refrigerant temperature sensor, and the outside air temperature sensor. The valve opening degree of the electric expansion valve is controlled based on the outside air temperature.

  According to the present invention, during heating operation, the temperature sensor detects the supercooling refrigerant temperature on the operation side and the subcooling refrigerant temperature on the stop side, respectively, and the supercooling refrigerant temperature on the operation side and the subcooling refrigerant temperature on the stop side are detected. Is equipped with a control means for controlling the opening degree of the electric expansion valve so that a predetermined temperature difference calculated from the rotational speed of the compressor is obtained. Can be fully pulled out to improve comfort.

  Hereinafter, an air conditioner according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. 1 to 4, the same reference numerals as those in FIG. 5 denote the same or equivalent components.

  First, the overall configuration of the air conditioner of the present embodiment will be described with reference to FIG. FIG. 1 is a configuration diagram of an air conditioner according to an embodiment of the present invention.

  In the air conditioner of this embodiment, a plurality of indoor units A and B are connected to one outdoor unit C. The two indoor units A and B include large-diameter pipe connection valves 3a and 3b provided in the large-diameter pipes 10a and 10b, and thin-diameter pipe connection valves 6a and 6b provided in the small-diameter pipes 11a and 11b. It is connected to the outdoor unit C. Each of the indoor units A and B is provided with indoor heat exchangers 4a and 4b, indoor fans 5a and 5b, and room temperature sensors 32a and 32b. On the other hand, the outdoor unit C includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 8, an outdoor fan 9, an outdoor air temperature sensor 24, an electric expansion valve 7 a corresponding to each of the indoor units A and B, and a small-diameter pipe. 7b is provided. In order to detect the main refrigerant temperature of the refrigerant circuit, a refrigerant discharge temperature sensor 22 is provided in the discharge pipe in the vicinity of the compressor 1 between the electric expansion valves 7a and 7b and the small diameter pipe connection valves 6a and 6b. Supercooled refrigerant temperature sensors 23a and 23b are provided in the piping.

  Next, the control device for the air conditioner of the present embodiment will be described with reference to FIG. FIG. 2 is a control block diagram of the air conditioner of FIG.

  In FIG. 2, 21 is an outdoor control device provided in the outdoor unit C, 31 a is an indoor control device of the indoor unit A, and 31 b is an indoor control device of the indoor unit B. The two indoor control devices 31a and 31b are connected to the outdoor control device 21 through data transmission lines 51a and 51b for transmitting and receiving control signals. Each of the indoor control devices 31a and 31b has room temperature sensors 32a and 32b for detecting the current room temperature, and correction parameters such as the capacity classes of the indoor units A and B and the volume classes of the indoor heat exchangers 4a and 4b. The stored storage devices 33a and 33b are connected.

  On the other hand, the outdoor control device 21 includes a refrigerant discharge temperature sensor 22 for detecting the temperature of the refrigerant discharged from the compressor 1, supercooled refrigerant temperature sensors 23a and 23b for detecting the supercooled refrigerant temperature, and outside air. An outside air temperature sensor 24 for detecting the temperature is connected. Further, although not shown in FIG. 2, the outdoor unit control device 21 has a compressor rotation speed detection means, a compressor rotation speed control means, and an electric expansion valve control means. The compressor 1 and the electric expansion valves 7a and 7b are controlled.

  An operation when both the indoor unit A and the indoor unit B are heated in the air conditioner configured as described above will be described below.

  When the heating operation is started, the indoor control devices 31a and 31b control the indoor fans 5a and 5b according to the set wind speed received from the remote controllers 41a and 41b, and control the control information such as the heating operation start command and the air conditioning load. To the device 21. These pieces of information are calculated based on the set temperature set by the remote controllers 41a and 41b and the room temperature detected by the room temperature sensors 32a and 32b.

  When the outdoor control device 21 receives a heating operation start command from the indoor units A and B, the outdoor control device 21 switches the four-way valve 2 to the heating cycle side, drives the outdoor fan 9 at a predetermined rotational speed, and controls the indoor units A and B. In accordance with the correction parameter, each electric expansion valve 7a, 7b is narrowed down to a predetermined initial opening for operation. Further, based on the rotational speed command value of the compressor 1 received from the indoor units A and B, the compressor rotational speed required for the operation of the two units is obtained by calculation to drive the compressor 1. Thereafter, the outdoor control device 21 compares the actual rotational speed detected by the compressor rotational speed detecting means (hereinafter referred to as the actual compressor rotational speed) with the target rotational speed obtained by the above calculation, and performs high-precision compression. The machine speed is controlled.

  The refrigerant in the refrigerant circuit flows in the direction of the arrow shown in FIG. 1 by the action of the control devices 31a, 31b, and 21. First, the refrigerant pressurized by the compressor 1 passes through the four-way valve 2 as superheated steam, flows into the indoor heat exchangers 4a and 4b, and dissipates heat to the air sent by the indoor fans 5a and 5b. Becomes a refrigerant. Thereafter, the pressure is reduced by passing through the electric expansion valves 7 a and 7 b, the air is heated by the outdoor fan 9 in the outdoor heat exchanger 8, and returns to the compressor 1 via the four-way valve 2.

  Next, the opening / closing operation of the electric expansion valves 7a and 7b adjusting the refrigerant circulation amount and the refrigerant temperature will be described with reference to FIG. FIG. 3 is a flowchart of the electric expansion valve control means in the outdoor control device of FIG.

  The electric expansion valve control means includes a refrigerant discharge temperature correction control S1, a compressor rotation speed deviation correction control S2, a distribution control S3, and an opening / closing control S4. The electric expansion valve control means includes the refrigerant discharge temperature Td detected by the refrigerant discharge temperature sensor 22, the compressor actual rotation speed N detected by the compressor rotation speed detection means, and the supercooling detected by the subcooling refrigerant temperature sensors 23a and 23b. Based on the refrigerant temperatures Tsca and Tscb and the outside air temperature To detected by the outside air temperature sensor 24, the valve opening degree of each of the electric expansion valves 7a and 7b is controlled.

  First, in the refrigerant discharge temperature correction control S1, the temperature of the refrigerant pressurized by the compressor 1, that is, the refrigerant discharge temperature Td is adjusted so that the electric expansion valves 7a and 7b have a predetermined temperature corresponding to the actual compressor speed N. Calculations are performed to correct the opening. This calculation uses a fuzzy calculation for correcting the refrigerant discharge temperature. When the refrigerant discharge temperature Td and the actual compressor speed N are substituted for the fuzzy calculation for correcting the refrigerant discharge temperature, correction of the electric expansion valves 7a and 7b is performed. The opening can be obtained with a sign. Hereinafter, the calculation result is referred to as a refrigerant discharge temperature correction opening degree ΔPtd.

  Next, in the compressor rotation speed deviation correction control S2, a correction opening degree ΔPn when the rotation speed of the compressor 1 fluctuates due to load fluctuation of the refrigerant circuit is obtained. For this calculation, the compressor actual rotational speed N is substituted, multiplied by a predetermined constant Knm, and a correction coefficient is added to obtain a signed correction opening degree ΔPn. Hereinafter, the calculation result is referred to as a compressor rotation speed fluctuation correction opening degree ΔPn.

  Next, in the distribution control S3, the number of operating indoor units A and B is determined in step S30, and the temperature difference is divided into processing during operation of two units in step S33 and processing during operation of one unit in steps S31 and S32. Tsc is calculated, and based on this, the corrected opening degree ΔPtsc is obtained.

  Here, the calculation during the operation of the two units is performed as distribution control for supplying an appropriate refrigerant circulation amount to each of the indoor units A and B. That is, the distribution control during the operation of the two units calculates the corrected opening degrees of the electric expansion valves 7a and 7b so that the supercooling refrigerant temperature Tsca of the indoor unit A and the supercooling refrigerant temperature Tscb of the indoor unit B become the same temperature. Therefore, the current temperature difference Tsc is substituted into the distribution control fuzzy calculation to obtain the corrected opening ΔPtsc with a sign. Hereinafter, the obtained result is referred to as a supercooled refrigerant temperature correction opening degree ΔPtsc. Note that the calculation during the operation of one unit will be separately described later.

  Next, in the opening / closing control S4, the target opening degrees Pa (n) and Pb (n) are obtained by adding the three corrected opening degrees ΔPtd, ΔPn, and ΔPtsc to the current opening degree of each of the electric expansion valves 7a and 7b. The electric expansion valves 7a and 7b are opened and closed in accordance with the target openings Pa (n) and Pb (n).

  The electric expansion valves 7a and 7b are controlled at predetermined intervals, and the refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit in the two-unit operation are continuously maintained in an optimum state.

  Next, single operation when the indoor unit A is operated and the indoor unit B is stopped in the heating operation will be described with reference to FIGS. 1 to 4. FIG. 4 is an explanatory diagram of the actual compressor speed and temperature difference correction constant used in the control of FIG.

  When the outdoor control device 21 shown in FIG. 2 confirms that only one of the indoor units A has started the heating operation based on the heating operation start command received through the data transmission lines 51a and 51b, as shown in FIG. 2 is switched to the heating cycle side, the outdoor fan 32a is driven at a predetermined rotational speed, the electric expansion valve 7a of the indoor unit A is narrowed to a predetermined initial opening for operation, and the electric expansion valve 7b of the indoor unit B is Narrow down to a predetermined initial opening for stopping. Furthermore, the outdoor control device 21 drives the compressor 1 by obtaining the compressor rotational speed necessary for one unit operation based on the command rotational speed of the compressor 1 received from the indoor unit A. Thereafter, in order to prevent the refrigerant from staying in the stopped indoor unit B and maintain the refrigerant circulation amount and the refrigerant temperature in the entire refrigerant circuit in an optimum state continuously, each electric expansion valve control means performs each electric expansion. The valves 7a and 7b are controlled to a predetermined opening degree.

  The opening and closing operation of the electric expansion valves 7a and 7b in the single unit operation will be specifically described. Each opening degree of the electric expansion valve is corrected by electric expansion valve control. As for the distribution control S3 at the time of single-unit operation shown in FIG. 3, it is necessary to obtain the correction opening degree in consideration of the air conditioning load of the operating indoor unit A and the heat leak amount of the stopped indoor unit B. Therefore, it is not possible to simply obtain the corrected opening degree by the same calculation as when two units are operating. Therefore, based on the parameters stored in the outdoor control device 21 and the actual compressor rotation speed N, the air conditioning load of the operating indoor unit A and the amount of heat leakage of the stopped indoor unit B are determined, The distribution control S3 is performed so that a predetermined temperature difference is generated between the operation side and the stop side supercooled refrigerant.

  In the distribution control S3 in this single-unit operation, first, as shown in step S31 of FIG. As shown in FIG. 4, the temperature difference correction constant Kso increases proportionally from the corrected lower limit compressor actual rotational speed to the corrected upper limit compressor actual rotational speed, and is constant otherwise. The upper limit is based on a value that suppresses stagnation of the refrigerant on the stop side that occurs when the actual compressor speed N is high, and the lower limit corrects a decrease in the refrigerant circulation rate that occurs during low rotation.

  In this way, setting the temperature difference when the actual compressor speed N is low to be lower than that when the compressor is high causes the supercooled refrigerant temperature Tsca of the operation-side indoor heat exchanger 4a to be increased at the time of low rotation. An object of the present invention is to obtain an appropriate refrigerant circulation amount without a shortage of the flow rate of the electric expansion valve 7a on the operation side.

  Next, as shown in step S32 of FIG. 3, a temperature difference correction constant Kso is added when calculating the current temperature difference. The result is substituted into the distribution control fuzzy calculation as shown in step S34, and the corrected opening ΔPstc is obtained with a sign. In step S31, the temperature difference correction constant Kso is obtained with a sign so that even if one of the indoor unit A and the indoor unit B is operated, the arithmetic expression in step S32 can be used without dividing the case. ing.

  By controlling the electric expansion valves 7a and 7b at predetermined intervals, it is possible to prevent the refrigerant from being insufficiently circulated to the indoor heat exchanger 4a on the operation side when the compressor is operating at a low speed in one unit operation. The refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit on the side are continuously maintained in an optimum state.

  According to this embodiment, in the air conditioner having a plurality of electric expansion valves 7a, 7b that can individually control the refrigerant flow rates for the plurality of indoor units A, B in the small-diameter pipes 11a, 11b, the electric expansion valves 7a, The refrigerant temperature sensors 23a and 23b for detecting the refrigerant temperature are provided between the 7b and the small-diameter pipe connection valves 6a and 6b. And controlling each of the electric expansion valves 7a and 7b such that the operation-side subcooling refrigerant temperature Tsca and the stop-side subcooling refrigerant temperature Tscb have a predetermined temperature difference calculated from the compressor rotational speed, It is possible to prevent the refrigerant circulation shortage to the indoor heat exchanger 4a on the operation side at the time of low circulation amount of single heating operation, and to sufficiently draw out the heating capacity and improve comfort even at the time of low circulation amount. so That.

  The air conditioner in which two indoor units A and B are connected to one outdoor unit C has been described above, but the present invention is also applicable to an air conditioner in which three or more indoor units are connected to one outdoor unit. The invention can be applied.

  In a multi-type air conditioner in which three or more indoor units are connected to one outdoor unit. When all indoor units are heated, the maximum and minimum temperatures are determined from the supercooled refrigerant temperature sensor corresponding to each indoor unit. By detecting the temperature and controlling the electric expansion valve so that this temperature difference is the same temperature, the refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit in each indoor unit can be continuously maintained in an optimum state. Is possible.

  Further, when the heating operation including the stopped indoor unit is performed, the average value of the supercooling refrigerant temperature on the operation side and the average value of the supercooling refrigerant temperature on the stop side are obtained, and this temperature difference is a predetermined temperature difference. Similarly, the refrigerant circulation amount and the refrigerant temperature in the refrigerant circuit on the operation side and the stop side can be continuously maintained in an optimal state.

It is a block diagram of the air conditioner which concerns on one Embodiment of this invention. It is a control block diagram of the air conditioner of FIG. It is a flowchart of the electric expansion valve control means in the outdoor control apparatus of FIG. It is explanatory drawing of the compressor real rotation speed and temperature difference correction constant used for control of FIG. It is a block diagram of the conventional air conditioner.

Explanation of symbols

A ... indoor unit, B ... indoor unit, C ... outdoor unit, 1 ... compressor, 2 ... four-way valve, 3a, 3b ... large diameter pipe connection valve, 4a, 4b ... indoor heat exchanger, 5a, 5b ... indoor fan 6a, 6b ... Small diameter pipe connection valve, 7a, 7b ... Electric expansion valve, 8 ... Outdoor heat exchanger, 9 ... Outdoor fan, 10a, 10b ... Large diameter pipe, 11a, 11b ... Small diameter pipe, 21 ... Outdoor Control device, 22 ... refrigerant discharge temperature sensor, 23a, 23b ... supercooled refrigerant temperature sensor, 24 ... outside air temperature sensor, 31a, 31b ... indoor control device, 32a, 32b ... room temperature sensor, 33a, 33b ... storage device, 41a, 41b ... remote control, 51a, 51b ... data transmission line.

Claims (3)

A plurality of indoor units that can be individually operated and stopped; and an outdoor unit that connects the plurality of indoor units in parallel. The outdoor unit includes a compressor that compresses refrigerant, and a pipe for each of the indoor units. A small-diameter pipe connection valve and a large-diameter pipe connection valve to be connected; an electric expansion valve that individually controls the refrigerant flow rate for the plurality of indoor units; and an excess between the electric expansion valve and the small-diameter pipe connection valve. In an air conditioner equipped with a supercooled refrigerant temperature sensor that detects a refrigerant temperature,
During heating operation, the supercooling refrigerant temperature sensor detects the operation-side supercooling refrigerant temperature and the stop-side supercooling refrigerant temperature, respectively, and the operation-side supercooling refrigerant temperature and the stop-side supercooling refrigerant temperature are An air conditioner comprising an electric expansion valve control means for controlling an opening degree of the electric expansion valve so as to obtain a predetermined temperature difference calculated from the rotation speed of the compressor.   2. The air conditioner according to claim 1, wherein when the heating operation is started, the electric expansion valve control means narrows the electric expansion valve on the operation side to an initial opening for operation and stops the electric expansion valve on the stop side. The initial opening degree is narrowed down, and the supercooling refrigerant temperature on the operation side and the supercooling refrigerant temperature on the stop side are periodically detected, and each temperature difference becomes a predetermined temperature difference calculated from the compressor rotational speed. An air conditioner that controls the electric expansion valve. The air conditioner according to claim 1, comprising a refrigerant discharge temperature sensor for detecting the temperature of the refrigerant discharged from the compressor and an outside air temperature sensor for detecting the outside air temperature, and the electric expansion valve control means Is detected by the refrigerant discharge temperature detected by the refrigerant discharge temperature sensor, the actual compressor rotation speed detected by the compressor rotation speed detection means, the supercooling refrigerant temperature detected by the supercooling refrigerant temperature sensor, and the outside air temperature sensor. An air conditioner that controls a valve opening degree of the electric expansion valve based on an outside air temperature.

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