JPH0745977B2 - Air conditioner - Google Patents

Description

Description: [Object of the Invention] (Industrial field of application) [0001] The present invention relates to an air conditioner equipped with a high-pressure release means for suppressing an abnormal increase in the high-pressure side pressure of a refrigeration cycle.

(Prior Art) Generally, an air conditioner includes a pressure sensor that detects the high-pressure side pressure of a refrigeration cycle, and as shown in FIG.
When the pressure P detected by the pressure sensor rises abnormally and reaches a set value Ps, for example 26.5 kg / cm ² G, high-pressure release is performed, such as reducing the capacity of the compressor or turning off the fan.
It is designed to suppress an abnormal rise in high-pressure side pressure.

(Problem to be Solved by the Invention) However, there is a problem that the high-pressure side pressure largely fluctuates after execution of the high-pressure release, and the refrigeration cycle becomes unstable.

The present invention has been made in view of the above circumstances,
An object of the invention is to provide an air conditioner capable of reliably suppressing an abnormal increase in the high-pressure side pressure, suppressing a fluctuation in the high-pressure side pressure to a small level, and always enabling stable operation. is there.

[Configuration of the Invention] (Means for Solving the Problem) A refrigeration cycle, a refrigeration cycle in which a compressor having a variable operating capacity, an outdoor heat exchanger, an indoor heat exchanger, and the like are sequentially connected to each other, and the refrigeration cycle A bypass pipe interposing a high pressure release valve provided from the high pressure side refrigerant pipe to the low pressure side refrigerant pipe of the cycle, a variable speed outdoor fan provided near the outdoor heat exchanger, and the operating capacity of the compressor are controlled. Means, means for controlling the opening and closing of the high pressure release valve, means for controlling the speed of the outdoor fan, a pressure sensor for detecting the high pressure side pressure of the refrigeration cycle, and the speed of increase of the pressure detected by the pressure sensor. With the detection means for detecting, the high pressure release valve opened, and the outdoor fan turned off, the operating capacity of the compressor is controlled in multiple stages from low capacity to high capacity. A plurality of stages of high-pressure release means for closing the high-pressure release valve, and a high-capacity operation of the compressor, the plurality of stages for switching control of the speed of the outdoor fan from a low speed to a high speed High pressure release means of, and these high pressure release means of each of the plurality of stages are sequentially associated from the detection speed of the detection means to the slow one, and when the pressure detected by the pressure sensor reaches a predetermined value, The high pressure release means corresponding to the detection speed of the detection means at that time is selected from the correspondence and executed.

(Operation) Based on the rate of increase of the pressure detected by the pressure sensor, the high pressure release means having different suppression effects are selectively executed.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, A is an outdoor unit, which has two variable capacity compressors 1 and 2. And this outdoor unit A
A branch unit B is connected to the branch unit B, and a plurality of indoor units C ₁ , C ₂ and C ₃ are connected to the branch unit B.

The variable capacity compressors 1 and 2 are connected in parallel via check valves 3 and 4, respectively, and the compressors 1 and 2, the four-way valve 5, the outdoor heat exchanger 6, the heating expansion valve 7 and the cooling cycle. Parallel body of check valve 8 for forming, liquid tank 9, electric flow control valve 11,21,3
1, cooling expansion valves 12,22,32 and heating cycle check valve 1
A beat pump type refrigeration cycle is configured by sequentially connecting a parallel body of 3,23,33, an indoor heat exchanger 14,24,34, a gas side opening / closing valve (electromagnetic opening / closing valve) 15,25,35, an accumulator 10 and the like. ing.

The cooling expansion valves 12, 22, 32 are respectively temperature sensitive tubes 12a, 22a,
32a, and these temperature sensitive tubes are connected to the indoor heat exchangers 14, 24, 3
It is attached to each of the 4 gas side refrigerant pipes.

That is, the indoor heat exchangers 14, 24, 34 are arranged in parallel.

Further, during the cooling operation, the refrigerant is caused to flow in the direction indicated by the solid line arrow to form the cooling cycle, and during the heating operation, the refrigerant is caused to flow in the direction indicated by the broken line arrow to form the heating cycle by the switching operation of the four-way valve 5. ing.

In addition, the oil separator 41 is connected to the refrigerant discharge side pipe of the compressor 1.
The oil bypass pipe 42 is provided from the oil separator 41 to the refrigerant suction side pipe of the compressor 1. Further, an oil separator 43 is provided on the refrigerant discharge side pipe of the compressor 2.
And an oil bypass pipe 44 extending from the oil separator 43 to the refrigerant suction side pipe of the compressor 2. The reference oil surface level positions of the cases of the compressors 1 and 2 are communicated with each other by an oil equalizing pipe 45, so that the lubricating oils can flow through each other.

On the other hand, a pressure sensor 46 is attached to the high pressure side refrigerant pipe of the refrigeration cycle.

Further, a bypass pipe 47 is provided from the high pressure side refrigerant pipe to the low pressure side refrigerant pipe, and a high pressure release valve (electromagnetic on-off valve) 48 is provided in the bypass pipe 47.

Further, an outdoor fan 49 is provided near the outdoor heat exchanger 6.

The control circuit is shown in FIG.

The outdoor unit A includes an outdoor control unit 50. The outdoor control unit 50 is composed of a microcomputer and its peripheral circuits, and has a pressure sensor 46 and a high pressure release valve outside.
48, an outdoor fan motor 49M, and inverter circuits 51, 52 are connected.

The inverter circuits 51 and 52 rectify the voltage of the AC power supply 53,
It is converted into AC voltage of a predetermined frequency by switching according to the command of the outdoor control unit 50, and the compressor motor 1M, 2M
Each is supplied as drive power.

The branching unit B includes a multi-control unit 60. The multi-control unit 60 is composed of a microcomputer and its peripheral circuits, and has flow rate adjusting valves 11, 21, 31 and open / close valves 15, 25, 35 connected to the outside.

The outdoor units C ₁ , C ₂ and C ₃ include indoor control units 70, 80 and 90. These indoor control units consist of a microcomputer and its peripheral circuits, and are externally operated by operation control units 71, 81, 91.
And indoor temperature sensors 72, 82, 92 are connected respectively.

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

Now, it is assumed that all indoor units are in cooling operation.

At this time, the indoor control unit 70 of the indoor unit C ₁ calculates the difference between the temperature detected by the indoor temperature sensor 72 and the set temperature determined by the driving operation unit 71, and the frequency setting signal f ₁ corresponding to the temperature difference is calculated. Is transferred to the multi-control unit 60 as the required cooling capacity.

Similarly, the indoor control units 80 and 90 of the indoor units C ₂ and C ₃ also use the frequency setting signals f ₂ and f ₃ as the required cooling capacity for the multi-control unit.
Transfer to 60.

The multi-control unit 60 obtains the required cooling capacity of each indoor unit based on the transferred frequency setting signal, and transfers the frequency setting signal f ₀ corresponding to the sum to the outdoor control unit 50.

The outdoor control unit 50 controls the number of operating compressors 1 and 2 and the operating frequency (output frequency of the inverter circuits 51 and 52) based on the transferred frequency setting signal f ₀ .

In this case, the outdoor control unit 50 shifts from the single operation of the compressor 1 to the double operation of the compressors 1 and 2 as the total required cooling capacity increases. That is, the operating capacity of the compressor is variable, including the change in the number of operating machines and the control of the operating frequency, and the operating capacity is switched and controlled in a plurality of stages from low capacity to high capacity.

In addition, the multi-control unit 60 corresponds to the flow rate adjusting valves 11, 21, respectively corresponding to the required cooling capacity of the indoor units C ₁ , C ₂ , C ₃ .
The opening degree of 31 is controlled to adjust the refrigerant flow rate to the indoor heat exchangers 14, 24, 34 to maintain the refrigerant superheat degree constant.

By the way, during this cooling operation, the outdoor control unit 50 operates as a pressure sensor.
The detected pressure P (high-pressure side pressure) of 46 is monitored, and the control shown in FIGS. 3 to 5 is performed according to the detected pressure P.

That is, the detected pressure P increases and a predetermined value P ₁ (for example, 2
When it exceeds 4.5 kg / cm ² G), an internal timer is set and the time t until the detected pressure P reaches a predetermined value P ₂ (for example, 25.5 kg / cm ² G) is counted.

Then, if the detected pressure P exceeds the predetermined value P ₁ before the count time t reaches the set time t ₅ , the count time t is compared with the set times t ₁ , t ₂ , t ₃ , t ₄ , t _6. To do.

Here, regarding the set time, for example, t ₁ = 0 to 5
S, t ₂ = 6 to 10 seconds, t ₃ = 11 to 20 seconds, t ₄ = 21 to 30 seconds, t ₅ =
31 seconds, t ₆ = 31-40 seconds.

If t = t ₁ , that is, if the rising speed of the detected pressure P is high, the A-mode high-pressure release means is executed. This A
The high-pressure release means in the mode simultaneously operates one compressor, turns off the outdoor fan 49, and opens the high-pressure release valve 48 at the same time, and has the greatest effect of suppressing an increase in the high-pressure side pressure.

If t = t ₂ , the B-mode high-pressure release means is executed. The B-mode high-pressure release means turns off the outdoor fan 49 and opens the high-pressure release valve 48 when the two compressors are in operation, and has the second largest suppressing effect on the increase in the high-pressure side pressure.

The A-mode and B-mode high-pressure release means switches the operating capacities of the compressors 1 and 2 from a low capacity to a high capacity in a plurality of stages with the high-pressure release valve 48 opened and the outdoor fan 49 turned off. It corresponds to a multi-stage high-pressure release means for controlling (that is, controlling the number of operating compressors 1 and 2 and operating frequency).

If t = t ₃ , the C mode high pressure release means is executed. This C-mode high-pressure release means operates when the two compressors are operating and the high-pressure release valve 48 is closed.
Since the outdoor fan 49 is operated at a constant speed L, the effect of suppressing the rise in the high-pressure side pressure is the second largest.

If t = t ₄ , the D-mode high pressure release means is executed. This D-mode high-pressure release means operates in the two compressor operating state and the high-pressure release valve 48 closed state.
The outdoor fan 49 operates at a medium speed M, and has the fourth largest suppressing effect on the increase in the high-pressure side pressure.

If t> t ₆ , the E-mode high-pressure release means is executed. This E-mode high-pressure release means operates when the two compressors are in operation and the high-pressure release valve 48 is closed.
The high speed H operation of the outdoor fan 49 is performed. That is, it is normal operation.

Incidentally, when the detection pressure P count time before it reaches a predetermined value P ₂ t has reached the set value t _5, to perform the pressure release means E mode. Further, if the detected pressure P reaches the set value P ₃ (> P _S ) without being able to suppress the abnormal rise, the operation is stopped completely.

The C-mode, D-mode, and E-mode high-pressure release means closes the high-pressure release valve 48, and compresses the compressors 1, 2
The outdoor fan 49
It corresponds to a multi-stage high-pressure release means for switching control of the speed from low speed to high speed in a plurality of steps.

In short, A mode, B mode, C mode, D mode,
And the E-mode high-pressure release means are sequentially associated from the faster rising speed of the detected pressure P to the slower rising speed,
If the sensed pressure P reaches a predetermined value P _2, it is one of the high pressure release means corresponding to the count time t (the rising speed of the sensed pressure P) of the time to execute by selecting from the correspondence.

In this way, when the rate of increase of the detected pressure P is high, by selecting and executing the high-pressure release means having a high suppression effect, the increase of the high-pressure side pressure reaches the conventional operating point (set value) P _S. It can be suppressed without fail.

When the rising speed of the detected pressure P is slow, by selecting and executing the high-pressure release means having a low suppressing effect, it is possible to suppress the fluctuation of the high-pressure side pressure after the execution.

Therefore, the fluctuation of the high-pressure side pressure becomes gentle as shown in FIG. 5, and stable operation is always possible.

On the other hand, the outdoor control unit 50 performs abnormality determination control of the pressure sensor 46 as shown in FIGS. 6 to 9.

That is, when the detected pressure P does not exceed the predetermined value Px within a certain time Ta from the start of operation (see FIG. 7), the pressure sensor
46 determines as abnormal.

Oil-equalizing operation in which the operating frequencies of the compressors 1 and 2 are relatively increased and decreased (Periodically executed to prevent uneven distribution of refrigeration oil in each compressor)
At this time, if the change in the detected pressure P is less than or equal to the predetermined value Py (see FIG. 8), it is determined that the pressure sensor 46 is abnormal.

If the detected pressure P does not fall below the predetermined value Pz even after a certain time Tb has passed since the operation was stopped (see FIG. 9), the pressure sensor 46
Is determined to be abnormal.

Then, when an abnormality is determined, the fact is notified by a display or the like.

In the above embodiment, only the high pressure release for the increase of the high pressure side pressure has been described, but the low pressure release for the decrease of the high pressure side pressure may be performed.

That is, since the outside air temperature is low during the intermediate period such as spring and autumn, the high-pressure side pressure may drop during the cooling operation.

Then, as shown in FIG. 10, fan motors 49aM, 49bM
With two outdoor fans, and the detected pressure P is a specified value Pa
When it largely drops below (for example, 10 kg / cm ² G), the interval operation (alternate operation) of the low pressure release means in the R ₆ mode and the R ₅ mode is executed. In this case, the R ₆ mode low pressure release means is first executed for 180 seconds, then the R ₅ mode low pressure release means is executed for 30 seconds, and this is repeated thereafter.

The R ₅ mode low-pressure release means turns off both outdoor fans and opens the high-pressure release valve 48, and has the greatest effect of suppressing the decrease in the high-pressure side pressure. The R ₅ mode low-pressure release means turns on one of the outdoor fans and opens the high-pressure release valve 48, and has the second largest suppressing effect against the decrease in the high-pressure side pressure.

When the detected pressure P enters between the predetermined values Pa and Pb (for example, 13 kg / cm ² G), the low pressure release means is sequentially shifted to the strong side from the R ₁ mode to the R ₅ mode for execution every minute.

The low pressure release means in the R ₁ mode is for operating both the outdoor fans at high speed H while the high pressure release valve 48 is closed. That is, it is normal operation.

The R ₂ mode low-pressure release means performs high-speed H operation of both outdoor fans and opens the high-pressure release valve 48, and the magnitude of the suppression effect on the decrease in the high-pressure side pressure is fifth from the top. The R ₃ mode low pressure release means performs high speed H operation of one outdoor fan, low speed L operation of the other outdoor fan, and opens the high pressure release valve 48. The size is the fourth from the top. The R ₄ mode low-pressure release means performs a constant-speed L operation of both outdoor fans and opens the high-pressure release valve 48, and the effect of suppressing the decrease in the high-pressure side pressure is third from the top.

When the detected pressure P enters between the predetermined values Pb and Pc (for example, 16 kg / cm ² G), the execution of the low pressure release means at the time of entry is held.

When the detected pressure P is Pd or more, the low pressure release means of the R ₁ mode, that is, the normal operation is executed.

When the detected pressure P enters a predetermined value Pd (for example, 18 kg / cm ² G), the low pressure release means is set to the weak side ₁ from R ₅ to R ₁ mode.
It shifts and executes every minute.

As described above, by selectively executing the low-pressure release means having different suppressing effects on the decrease in the high-pressure side pressure according to the detected pressure P, stable operation can be performed even in the intermediate period.

[Effects of the Invention] As described above, according to the present invention, a refrigeration cycle including a compressor, an outdoor heat exchanger, an indoor heat exchanger, and the like having variable operating capacities in order, and a high pressure of the refrigeration cycle. A bypass pipe interposing a high pressure release valve provided from the side refrigerant pipe to the low pressure side refrigerant pipe, a variable speed outdoor fan provided near the outdoor heat exchanger, and means for controlling the operating capacity of the compressor, Means for controlling the opening and closing of the high pressure release valve, means for controlling the speed of the outdoor fan, and a pressure sensor for detecting the high pressure side pressure of the refrigeration cycle,
A plurality of operating capacities of the compressor from a low capacity to a high capacity are detected in a state where the detecting means for detecting the speed of increase in the pressure detected by the pressure sensor, the high pressure release valve is opened, and the outdoor fan is turned off. Switching the speed of the outdoor fan from a constant speed to a high speed in a plurality of stages in a state where the high pressure release means of a plurality of stages for switching control to a stage and the high pressure release valve are closed and the compressor is in a high capacity operation. The high pressure release means of a plurality of stages to be controlled, and the high pressure release means of each of these multiple stages are sequentially associated from the faster detection speed of the detection means to the slower speed, and the pressure detected by the pressure sensor is a predetermined value. When a high pressure side is reached, a means for selecting and executing one high pressure release means corresponding to the detection speed of the detection means at that time from the correspondence is provided. It can be suppressed indeed, yet it is possible to suppress the fluctuation of the high side pressure, always provide an air conditioner that enables stable operation.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a control circuit in an embodiment of the present invention, FIG. 2 is a diagram showing a configuration of a refrigeration cycle in the same embodiment, and FIG. 3 is a diagram for explaining high pressure release control in the same embodiment. FIG. 4, FIG. 4 and FIG. 5 are diagrams showing changes in the detected pressure related to the high pressure release control of the same embodiment, and FIG. 6 is a flow chart for explaining abnormality determination control of the pressure sensor in the same embodiment, 7 to 9 are views showing changes in the detected pressure according to the abnormality determination control of the embodiment, respectively, and FIG. 10 is a view showing a configuration of a main part of a modified example of the control circuit in the embodiment, and FIG. FIG. 12 is a flow chart for explaining the operation of the modified example, FIG. 12 is a diagram showing changes in the detected pressure in the modified example, and FIG. 13 is a diagram showing changes in the detected pressure in the conventional air conditioner. A: outdoor unit, B: branch unit, C ₁ , C ₂ , C ₃
…… Indoor unit, 1,2 …… Variable capacity compressor, 46 …… Pressure sensor, 49 …… Outdoor fan, 50 …… Outdoor control unit, 60 ・ ・ ・
… Multi control, 70,80,90 …… Indoor control.

Claims (1)

[Claims] 1. A compressor having a variable operating capacity, an outdoor heat exchanger,
A refrigeration cycle configured by sequentially connecting indoor heat exchangers and the like, a bypass pipe with a high pressure release valve provided from the high pressure side refrigerant pipe to the low pressure side refrigerant pipe of this refrigeration cycle, and the outdoor heat exchanger A variable speed outdoor fan provided, a means for controlling the operating capacity of the compressor, a means for controlling the opening and closing of the high pressure release valve, a means for controlling the speed of the outdoor fan, and a high pressure side pressure of the refrigeration cycle. A pressure sensor for detecting the pressure, a detection means for detecting the rate of increase in the pressure detected by the pressure sensor, an opening of the high pressure release valve, and an operation in which the outdoor fan is turned off. A plurality of high pressure release means for switching control from a low capacity to a high capacity in a plurality of stages, a state in which the high pressure release valve is closed, and the compressor is operated in a high capacity. Thus, a plurality of high-pressure release means for controlling the speed of the outdoor fan to switch from a low speed to a high speed in a plurality of steps, and the high-pressure release means of each of the plurality of steps are arranged from a higher detection speed to a lower detection speed. When the pressure detected by the pressure sensor reaches a predetermined value, one high pressure release means corresponding to the detection speed of the detection means at that time is selected from the correspondence and executed. An air conditioner characterized by comprising: