JPH0627588B2 - Air conditioner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly to an air conditioner having an improved equalization control system in a refrigerant pipe after a compressor is stopped.

(Prior Art) In an air conditioner in which a condenser and an evaporator are connected to a compressor so that the refrigerant can circulate, the refrigerant high and low pressure state in the refrigerant pipe during the previous operation continues until the compressor is restarted. Is
The compressor will be overloaded and will not start up smoothly. Therefore, in order to reduce the starting load of the compressor,
Every time the compressor is stopped, it is necessary to equalize the pressure in the refrigerant pipe to eliminate the pressure difference. A specific example related to such pressure equalization is disclosed in Japanese Patent Laid-Open No. 56-135774. FIG. 6 shows a refrigerant circuit diagram of the device configured as an air conditioner. As shown in FIG. 6, a condenser is provided between a discharge port 52 and a suction port 53 of a rotary type compressor 51. 54,
The expansion mechanism 55 and the evaporator 56 are sequentially connected to form a refrigerant circulation circuit. By circulating the refrigerant in the direction of the arrow in the figure, for example, if the evaporator 56 is arranged indoors, the cooling operation is performed.

In the above apparatus, a bypass port 58 is further provided in the cylinder chamber 57 of the compressor 51, and a valve body 60 biased to the valve opening side by a spring 59 is provided in the bypass port 58.
An on-off valve 61 having the inside is connected. A first bypass passage 62 is provided between the opening / closing valve 61 and the suction port 53. Then, in order to operate the valve body 60 of the opening / closing valve 61 to the valve closing side, the back pressure port 63 of the opening / closing valve 61 is connected to the communication pipe 65 in which the first capillary tube 6 is interposed. A pipe 65 is connected to the suction port 53 by a second bypass passage 67 provided with an electromagnetic valve 66 and to the discharge port 52 by a third bypass passage 69 provided with a second capillary tube 68. There is.

In the device having the above configuration, the effective compression volume in the cylinder chamber 57 can be changed by switching the communication state between the suction port 53 and the bypass port 58 with the opening / closing valve 61. The opening / closing operation of the opening / closing valve 61 is performed by the compressor 5
The high-pressure pressure of the high-pressure gas refrigerant discharged from the discharge port 52 in one operation acts on the back pressure port 63 of the opening / closing valve 61 by switching the solenoid valve 66. With the above configuration, the compression capacity of the compressor 51 can be adjusted, and the solenoid valve 6 can be further operated when the compressor 51 is stopped.
By opening 6 the second bypass 67 and the third
The suction port 53 and the discharge port 52 are communicated with each other through the bypass path 69, and the suction port 53 and the bypass port 58 are communicated with each other through the first bypass path 62, so that the high pressure on the discharge port 52 side of the compressor 51 is obtained. The pressure is equalized with the low pressure on the suction port 53 side.

(Problems to be Solved by the Invention) In the air conditioner as described above, it is necessary to equalize the pressure in the refrigerant pipe after the compressor is stopped in as short a time as possible. This is to ensure that the user's request for re-operation can be met at all times, and that the room temperature has reached the set temperature during air conditioning operation (thermo
The reason is that if the compressor is stopped due to (being turned off) and then the thermo is turned on in this state, if the compressor cannot start immediately, it will impair the habitability of the user. However, the above-described conventional bypass passage around the compressor, for example, the third bypass passage is provided for introducing pressure, and the flow rate flowing therethrough is provided via the flow rate resistance means composed of the second capillary tube. Is configured so as not to affect the flow rate of the refrigerant circulation circuit as much as possible. Therefore, it takes a long time to equalize the high and low pressure states in the entire refrigerant pipe through the bypass passage that cannot take a large flow rate. Therefore, in the device in which the electric expansion valve is provided in the liquid pipe connecting the condenser and the evaporator, the electric expansion valve is fully opened at substantially the same time as the compressor is stopped, and the electric power is supplied from the discharge port of the compressor. The high pressure gas and liquid refrigerant up to the expansion valve and the low pressure liquid and gas refrigerant from the electric expansion valve to the suction port of the compressor are equalized. Although it is possible to shorten the pressure equalization time by such an operation, in this method, rapid pressure mixing, that is, refrigerant flow appears as liquid back, for example, in a device in which an accumulator is provided in the suction pipe of the compressor. However, due to extreme accumulation of liquid in this accumulator, when restarting, problems such as reduction of the refrigerant flowing through the refrigerant pipe or liquid compression of the compressor may occur. Further, a pressure equalizing noise is generated due to a sudden mixture of high and low pressures during the pressure equalizing, and particularly during the cooling operation in which the indoor unit side is in a low pressure state, the pressure equalizing noise is transmitted to the indoor side, and the user feels uncomfortable. It was supposed to cause it.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to reduce the occurrence of liquid bag and pressure equalizing noise in an air conditioner in which an electric expansion valve is provided in a liquid pipe. An object is to provide an air conditioner having a pressure equalizing control function.

(Means for Solving the Problems) Then, the air conditioner of the present invention, as shown in FIG.
A refrigerant circulation circuit for returning the refrigerant discharged from the compressor 1 to the compressor 1 from the condenser 8 via the evaporator 18 is formed, and the liquid pipe 1 between the condenser 8 and the evaporator 18 is formed.
An air conditioner in which electric expansion valves 13 and 16 are provided at 0, 12, and 15, and the liquid pipe 1 is provided after the compressor 1 is stopped.
The opening degree of the electric expansion valves 13 and 16 is once reduced to a small opening degree or less at which the high and low refrigerant pressure differences among 0, 12, and 15 can be substantially maintained, and then the opening degrees of the electric expansion valves 13 and 16 are opened. It has a pressure equalizing control means 43 for controlling so that the pressure spreads.

(Operation) In the above device, the electric expansion valves 13 and 16 are widened when the compressor is stopped so that the above-mentioned liquid backing and rapid pressure equalization accompanied by the generation of pressure equalizing noise do not occur. Is to reduce the pressure once to suppress the pressure equalization, and then to control the pressure equalization control so as to widen the opening of the electric expansion valves 13 and 16 so that the pressure equalization is gradually performed. Means 43
Made by. Since the pressure equalization is gradually performed in this manner, it is possible to suppress the occurrence of liquid back and pressure equalization noise.

(Embodiment) Next, an air conditioner of the present invention will be described in detail with reference to the drawings by taking an air conditioner as an example.

First, FIG. 2 shows a refrigerant circuit diagram of a multi-type air conditioner equipped with four indoor units.
Indicates an outdoor unit, and A to D indicate first to fourth indoor units, respectively. The outdoor unit X is a compressor 1
have. This compressor 1 has a construction in which a starting load reducing function similar to that of the above-mentioned bypass path construction is built in, and the capacity of this compressor 1 is controlled by an inverter 2. The pipe 4 is connected to the four-way switching valve 5. A first gas pipe 6 and a second gas pipe 7 are connected to the four-way switching valve 5, and an outdoor heat exchanger 8 is connected to the second gas pipe 7. An outdoor fan 9 is attached to the outdoor heat exchanger 8. The outdoor heat exchanger 8 has a first liquid pipe 1
0, the liquid receiver 11, and the second liquid pipe 12 are sequentially connected,
A first electric expansion valve 13 is interposed in the first liquid pipe 10. The second liquid pipe 12 is connected to a header 14, but a plurality of header pipes, from the header 14, four pipes in the case of FIG.
The liquid side branch pipes 15 ... 15 are branched, and the second electric expansion valves 16.
Is installed. On the other hand, four gas side branch pipes 17 ... 17 branch from the first gas pipe 6 corresponding to the above, and the indoor heat exchanger 18 ...
18 is connected. In addition, an indoor fan 19 is attached to each indoor heat exchanger 18, and the indoor units A to D are configured by the both fans 18 and 19. Further, the liquid receiver 11
And the suction pipe 4 of the compressor 1 are connected by a pipe 20, and a capillary tube 21 is provided in the pipe 20. In the figure, 22 is a gas closing valve, 23 is a liquid closing valve, 24 and 25 are mufflers, 26
Indicate the accumulators, respectively. In the above air conditioner, as shown by the solid line arrow in the figure, the compressor 1
The refrigerant discharged from the compressor is circulated from the outdoor heat exchanger 8 serving as a condenser to the indoor heat exchanger 18 serving as an evaporator to perform a cooling operation, and conversely, is discharged from the compressor 1. The indoor heat exchanger 1 that serves as a condenser for the generated refrigerant
The heating operation is performed by circulating the heat from 8 to the outdoor heat exchanger 8 serving as an evaporator (indicated by a broken line arrow in the figure).

In the refrigerant circuit, the first temperature sensor 31 is attached to a position on the outlet side of the capillary tube 21, and the first temperature sensor 31 detects the pressure equivalent saturation temperature T1 of the low pressure gas refrigerant. It is for doing. Further, the suction pipe 4 of the compressor 1 is provided with a second temperature sensor 32, while the liquid side branch pipes 15 ... 15 are provided with a third temperature sensor 33.
The fourth temperature sensors 34 ... 34 are attached to the respective .16, but these temperature sensors 32, 33,
The function of 34 will be described later.

FIG. 3 shows a block diagram of the control system of the air conditioner. As shown in the figure, the outdoor unit X includes the outdoor control device 35,
Further, each indoor unit A to D has an indoor control device 36, respectively. An operation switch 37 and an indoor thermostat 38 are connected to the indoor control device 36, respectively.
Corresponding to the operation command signal issued from the indoor control device 36 to the outdoor control device 35 when the operation switch 37 is ON and the room temperature does not reach the set temperature, and the temperature difference between the detected room temperature and the set temperature. .DELTA.T signal to be output respectively.

On the other hand, the outdoor control device 35 includes a frequency control unit 41 that controls the frequency of the inverter 2 based on the ΔT signals of the indoor units A to D that have the operation command. Further, the outdoor control device 35 further opens the first and second electric expansion valves 13, 16 ... 16 based on the temperatures detected by the first to fourth temperature sensors 31 to 34 during the operation of the compressor 1. And a valve control unit 42 for controlling the opening degree, and a pressure equalization control unit for controlling the opening degree of the first and / or second electric expansion valves 13, 16 ... And 43.

First, a method of controlling the first and second electric expansion valves 13, 16, ... 16 by the valve control unit 42 during operation of the compressor 1 will be described. During the cooling operation, the first electric expansion valve 13 is kept fully open and the second electric expansion valves 16 ...
The opening degree of 16 is controlled so that the degree of superheat of the gas refrigerant evaporated in each indoor heat exchanger 18 ... In this case, the difference between the low pressure equivalent saturation temperature T1 detected by the first temperature sensor 31 and the evaporated refrigerant temperature T4 ... T4 detected by the fourth temperature sensor 34, that is, the detected superheat degree (T4-T1)
Then, control is performed to increase / decrease the opening degree of each second electric expansion valve 16 ... 16 by an opening degree proportional to the deviation from the reference superheat degree.

On the other hand, during the heating operation, the degree of superheat of the refrigerant that evaporates in the outdoor heat exchanger 8 is controlled by the first electric expansion valve 13, and the second electric expansion valves 16 ... Control is performed so that the condensed refrigerant temperatures at the outlets of the heat exchangers 18 ... The former obtains the difference between the low pressure equivalent saturation temperature T1 detected by the first temperature sensor 31 and the evaporating refrigerant temperature T2 detected by the second temperature sensor 32, and also detects this superheat degree (T2-T1) and the reference. The opening degree of the first electric expansion valve 13 is controlled based on the deviation from the degree of superheat.

The control of the second electric expansion valves 16 ... 16 is performed by the third temperature sensors 33.
The temperature T3 ... T3 of the condensed refrigerant at the outlet of 18 is detected, the average temperature Tm of these detected temperatures T3 ... T3 is calculated, and the opening degree of each of the second electric expansion valves 16 ... This is done by increasing or decreasing by an amount proportional to the temperature difference (Tm-T3) between the average temperature Tm and the detected temperature T3 ... T3.

As described above, the operation command signals from the indoor units A to D and Δ
The air conditioning operation is continued while performing the capacity control of the compressor 1 according to the T signal and the opening control of the electric expansion valves 13 and 16, but here, in all the indoor units A to D. When the operation switch 37 is turned off, or when the temperature in all the rooms during operation reaches the set temperature, the operation command signal is not output from the indoor control device 36, and the compressor 1 is stopped at this time. To be done. Then, when the next operation command signal is output, the compressor is stopped by the frequency controller 41 in order to equalize the high and low refrigerant pressure difference generated in the refrigerant pipe so that the compressor 1 can be immediately started. A pressure equalizing control unit 43 is provided which receives the signal and controls the opening degree for equalizing the pressure of each of the electric expansion valves 13 and 16, and performs the control shown in the flowchart of FIG.

The control method in the pressure equalization control unit 43 will be described below with reference to the flowchart of FIG. 4 and the state explanatory view of FIG. As described above, while the air conditioning operation is performed while the drive control of the compressor 1 is controlled by the frequency control unit 41 and the opening degree control of each of the electric expansion valves 13, 16 is controlled by the valve control unit 42, the pressure equalization control unit is performed. At 43, as shown in step S1 of FIG. 4, the process waits in the state of waiting for the input of the compressor stop signal. At this time, as shown in FIG. 5, the refrigerant circulates in the refrigerant pipe in a high pressure state on the discharge pipe 3 side of the compressor 1 and in a low pressure state on the suction pipe 4 side. When the compressor 1 is stopped, that is, when the frequency controller 41 outputs a stop signal to the inverter 2, a compressor stop signal is also output from the frequency controller 41 to the pressure equalizing controller 43. In response to this, the processing step shifts from step S1 to S2 in FIG.
Steps S2 and S3 are the electric expansion valve whose opening has been controlled up to that point, that is, the second electric expansion valve 16 corresponding to the indoor units A to D that have been operated until that time during the cooling operation, while the heating operation is performed. At times, the first electric expansion valve 1
3 and the second electric expansion valve 16 corresponding to the indoor units A to D that have been operated until then, the one having an opening of the set opening Pk or more is determined (step S2), and the opening of Pk or more is set. In step S1, the opening P is controlled so as to be once smaller than the set opening Pk (step S3). This is because when the opening P during operation is maintained even after the compressor 1 is stopped, the refrigerant circulation state in the refrigerant pipe is stopped by stopping the compressor 1 In addition, the high-pressure refrigerant is mixed in according to the opening degree of the electric expansion valve, and a pressure equalizing sound is generated along with the pressure-equalizing refrigerant flow. Therefore, in order to prevent such a refrigerant flow, an opening that can prevent the refrigerant flow that attempts to equalize the pressure as described above, that is, a small opening that can substantially maintain the high and low refrigerant pressure difference is obtained in advance, This opening degree is set as the set opening degree Pk, and the opening degree is once reduced below this Pk. Then, in step S4, after maintaining the above state for a short time t1 until the pressure state in the refrigerant pipe after the above operation is substantially stable, the process proceeds to step S5, and the once reduced opening P is almost fully opened. The opening control is performed by gradually expanding the opening Po to the opening side over a time tm (for example, 1 minute 30 seconds). During this period, as shown in FIG. 5, the high pressure side of the refrigerant pipe pressure is gradually equalized with the low pressure side. In particular, during the beginning of the period when the pressure difference is high, the rate of increase in the opening degree P of the electric expansion valve is reduced to control the opening degree so that the refrigerant flow noise accompanying the pressure equalization does not occur. Step S5
In, after reaching the substantially full opening degree Po, the process proceeds to step S6, and is held in that state for a time t2 so as to be completely equalized, and in step S7, the opening degree of each electric expansion valve is changed. The pressure equalization control is ended by setting the opening Pc in the fully closed state. After this, the pressure equalization control unit 43 issues a pressure equalization control end signal to the frequency control unit 41, and at the same time as step S1.
Then, the process returns to the next compressor stop signal input waiting state. Further, the frequency control unit 41 and the valve control unit 42 prepare for the next operation command signal from the indoor control device 36 side, and when the operation command signal is generated, after setting the respective initial values, the above-mentioned operation is performed. The compression function force control and the electric expansion valve opening degree control are restarted.

In the above embodiment, as described above, the discharge pipe 3 is passed through the bypass path for reducing the starting load which is built in the compressor 1.
The pressure of the high and low gas refrigerant between the suction side and the suction pipe 4 side is equalized, and in order to shorten the pressure equalization time, the electric expansion valve on the liquid pipe side is opened to equalize pressure on this liquid pipe side. By performing the opening control as described above, it is possible to suppress the generation of refrigerant mixing noise and flow noise due to the rapid pressure equalization that has occurred in the past, and eliminate the occurrence of troubles such as liquid back. can do.

In the above description, an example in which the inverter type multi-type air conditioner is used is shown, but the present invention can also be applied to an air conditioner having only one indoor unit or a refrigerating device having a compressor having another configuration. is there. Further, in the above embodiment, the cooling / warming operation mode has been described, but the same operation can be performed in an apparatus that performs only one of the operations, and in this case, the first electric expansion valve 13 and the second electric operation are performed. It is possible to adopt a configuration including any one of the expansion valves 16 ... Further, at this time, in the conventional device, an abnormal noise at the time of pressure equalization was generated in the indoor side during the cooling operation in which the indoor unit side is on the low pressure side, but when it is only necessary to prevent this, the cooling operation is performed. The pressure equalizing control means may be provided only occasionally. Further, although the opening of the electric expansion valve, which is once set to a small opening during the pressure equalization control, is configured to gradually open in the above embodiment, for example, it is maintained at a slightly larger opening than the small opening for a while, It is also possible to adopt a step-like opening control configuration in which the initial high-low pressure difference is reduced to some extent and then the full-open state is reached.

(Effect of the Invention) As described above, in the air conditioner of the present invention, after the compressor is stopped, the opening degree of the electric expansion valve is set to a small opening degree that can substantially maintain the high and low refrigerant pressure difference in the liquid pipe. The opening is controlled so that it decreases once and then spreads to the open side, and pressure equalization gradually proceeds, so when the conventional expansion valve was fully opened with the compressor stopped. It is possible to suppress the occurrence of pressure equalizing noise and the occurrence of trouble such as liquid back.

[Brief description of drawings]

1 to 5 show an embodiment of an air conditioner of the present invention. FIG. 1 is a functional system diagram, FIG. 2 is a refrigerant circuit diagram, FIG. 3 is a control system block diagram, and FIG. FIG. 5 is a flow chart diagram of the pressure equalization control, FIG. 5 is a state explanatory diagram showing the relationship between the opening degree of the electric expansion valve and the refrigerant pipe high / low pressure state and the elapsed time in the pressure equalization control, and FIG. It is a refrigerant circuit diagram of a harmony machine. 1 ... Compressor, 8 ... Outdoor heat exchanger (condenser), 10 ...
... first liquid pipe, 12 ... second liquid pipe, 13 ... first electric expansion valve, 15 ... liquid side branch pipe, 16 ... second electric expansion valve, 18
…… Indoor heat exchanger (evaporator), 43 …… Equalization control unit (equalization control means).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Matsumoto 1000 Otani, Okamoto Town, Kusatsu City, Shiga Prefecture 2 Daikin Industry Co., Ltd. Shiga Plant (72) Inventor Takayuki Sugimoto 1000 Otani, Okamoto Town, Kusatsu City, Shiga Prefecture No. 2 Shiga Works of Daikin Industries, Ltd.

Claims (1)

[Claims] 1. A refrigerant circulation circuit for returning the refrigerant discharged from a compressor (1) to the compressor (1) from a condenser (8) through an evaporator (18), and at the same time, the condensation is carried out. Liquid pipes (10) (12) (15) between the vessel (8) and the evaporator (18)
An air conditioner comprising a motor-operated expansion valve (13) (16) interposed in the liquid pipe (10) (1) after the compressor (1) is stopped.
2) The opening degree of the electric expansion valve (13) (16) is once reduced to a value equal to or smaller than a small opening degree capable of substantially maintaining the high and low refrigerant pressure difference in (15), and then the electric expansion valve (13) (16). An air conditioner having a pressure equalizing control means (43) for controlling the opening degree of the valve so as to widen it to the open side.