JPH01203858A - Air conditioner - Google Patents

Abstract

PURPOSE:To perform stable operation by reducing the operating frequency of compressors in case where there is an excessive pressure on the high pressure side in order to immediately control an abnormal pressure increase on the high pressure side. CONSTITUTION:The outdoor control section 50 monitors the detected pressure (high pressure side pressure) by a pressure sensor 46 while a cooling mode operation is being performed, and reduces the operating frequencies F1, F2 of compressors 1, 2 if the detected pressure exceeds the set limit. At this time, the rate of reduction is made identical to that of increase. The outdoor control section 50 also detects the inclination of the pressure increase, and, if the inclination is less than a predetermined value, zero or less for instance, it stops reducing the operating frequencies F1, F2. The operating frequencies F1, F2 are maintained there for a certain time period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Part 1 of the Invention] (Field of Industrial Application) The present invention relates to a multi-type air conditioner comprising an outdoor unit and a plurality of indoor units.

There is one shown in the figure.

A is an outdoor unit and has two variable capacity compressors. A branch unit B is connected to this outdoor unit A, and a plurality of indoor units C, C2, and C3 are connected to the branch unit B+.

That is, the indoor units C1, C2, and C3 use the frequency setting signals f, , f to set the required capacity according to their respective air conditioning loads.
2. It is sent to branch unit B as f3.

Branching unit B receives the received frequency setting signal f1.
f2. The required capacity of each indoor unit is determined from f3, and a frequency setting signal fo corresponding to the total sum is sent to the outdoor unit A.

The outdoor unit A then controls the number of operating compressors and the operating frequency according to the frequency setting signal fo that is sent.

(Problem to be solved by the invention) By the way, in such an air conditioner, when the indoor and outdoor air conditions are both overloaded during cooling operation, and the indoor unit capacity is large (the number of operating indoor units is If the pressure on the high pressure side of the refrigeration cycle increases abnormally,
Adversely affects the life of refrigeration cycle equipment.

In addition, during heating operation, both indoor and outdoor air conditions are overloaded, and the indoor unit capacity is small (minimum capacity;
When one indoor unit is in operation), the high-pressure side pressure rises abnormally even when the indoor air flow rate is low. For example, this happens when starting up or when the number of operating indoor units decreases.

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide an air conditioner that can immediately suppress abnormal increases in pressure on the high pressure side and always enable stable operation. be.

[(1M configuration) of the invention] (Means for solving the problem) Means for detecting the pressure on the high pressure side of the refrigeration cycle, and means for reducing the operating frequency of each of the compressors when the detected pressure becomes a set value or higher. and means for detecting the slope of the increase in the detected pressure, and means for stopping the reduction in the operating frequency when the detected slope becomes equal to or less than a predetermined value.

(Function) When the pressure on the high honey side of the refrigeration cycle exceeds the set value, the operating frequency of the compressor decreases by 1. Then, when the slope of the increase in the high pressure side pressure becomes less than a predetermined value, the operating frequency is reduced or stopped.

(Example) As shown in FIG. 1, in which parts are given the same reference numerals and their explanations are omitted, the outdoor unit 1-A is equipped with two variable capacity compressors 1 and 2. 2 are connected in parallel via check valves 3 and 4, respectively.

A parallel body of compressors 1 and 2, a four-way valve 5, an outdoor heat exchanger 6, a heating expansion valve 7 and a cooling cycle forming check valve 8,
Liquid tank 9, electric flow rate adjustment valve 11, 21, 31
, a parallel body of cooling expansion valves 12, 22° 32 and heating cycle forming check valves 13, 23° 33, indoor heat exchanger 14,
24, 34, gas side on-off valve (electromagnetic on-off valve') 15.25
, 35, accumulator 10, etc. are successively connected to form a heat pump type refrigeration cycle.

Note that the cooling expansion valves 12, 22, and 32 each have temperature-sensing tubes 12a, 22a, and 32a, and these temperature-sensing tubes are attached to the gas side refrigerant piping of the indoor heat exchanger 14, 24, and 34, respectively. There is.

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

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

In addition, an oil separator 4 is installed on the refrigerant discharge side piping of the compressor 1.
1 is provided, and an 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 piping of the compressor 2, and an oil bypass pipe 44 is provided from the oil separator 43 to the refrigerant suction side piping of the compressor 2.

The respective reference curved surface level positions of the cases of the compressors 1.2 are communicated with each other through oil equalizing pipes 45, allowing mutual circulation of lubricating oil.

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

The control circuit is shown in FIG.

The outdoor unit A includes an outdoor control section 50. This outdoor control section 50 is composed of a microcomputer, its peripheral circuits, etc., and is externally connected to a pressure sensor 46 and inverter circuits 51 and 52.

The inverter circuits 51 and 52 rectify the voltage of the AC power supply 53, convert it into an AC voltage of a predetermined frequency by switching according to a command from the outdoor control unit 50, and supply it as driving power to the compressor motors IM and 2M, respectively. It is something to do.

Branching unit B includes a multi-control unit 60. This multi-control unit 60 is composed of a microcomputer and its peripheral circuits, and externally includes flow rate regulating valves 11, 21.3.
1 and an on-off valve 15.25°35 are connected.

The indoor units C1, C2, and C3 are equipped with an indoor control section 70.8.
It has a value of 0.90. These indoor control units consist of a microcomputer and its peripheral circuits, and are externally connected to operation control units 71, 81, 91 and indoor temperature sensors 72, 8.
2.92 are connected respectively.

Next, in the configuration as shown in Figures 3 and 4,
The operation will be explained with reference to the figures.

It is assumed that all indoor units are currently performing cooling operation.

At this time, the indoor control section 70 of the indoor unit C7 calculates the difference between the temperature detected by the indoor temperature sensor 72 and the set temperature determined by the operation operation section 71, and requests a frequency setting signal f1 corresponding to the temperature difference. Multi-control unit 60 as cooling capacity
Transfer to.

Similarly, indoor unit c2. C3 indoor control section 80.9
0 also transfers the frequency setting signal '2+'3 to the multi-control unit 60 as the required cooling capacity.

The multi-control unit 60 determines the required cooling capacity of each indoor unit based on the transferred frequency setting signal, and generates a frequency setting signal f corresponding to the sum total.

is transferred to the outdoor control unit 50.

The outdoor control unit 50 receives the transferred frequency setting signal f.

Based on the number of operating compressors 1.2 and operating frequency (
The output frequency of the inverter circuits 51 and 52 is controlled.

In this case, the outdoor control unit 50 shifts from operating one compressor 1 to operating three compressors 1 and 2 as the total required cooling capacity increases.

Note that the multi-control unit 60 controls the indoor unit cl.

The degree of superheating of the refrigerant is kept constant by controlling the opening degree of the corresponding flow rate adjustment valves 11, 21.31 according to the required cooling capacity of C2 and C3, and adjusting the refrigerant flow rate to the indoor heat exchanger 14, 24, 34. to be maintained.

By the way, during this cooling operation, the outdoor control unit 50 monitors the detected pressure (high pressure side pressure) of the pressure sensor 46, and when the detected pressure exceeds the set value Ps (as shown in FIG. '3),
The operating frequencies F, , F2 of compressors 1.2 are both lowered.

In this case, the rate of fall should be the same as the rate of rise.

Furthermore, the outdoor control unit 50 controls the slope of the increase in the detected pressure (Δ
P/Δt), and when the detected slope becomes less than a predetermined value, for example "zero" or less, the operating frequency F,
, stop the decline of F2.

Then, the operating frequencies F, .

In this way, by lowering the operating frequencies Fl and F2 of the compressor 1.2 when the high-pressure side pressure becomes equal to or higher than the set value Ps, an abnormal increase in the high-pressure side pressure can be immediately suppressed. Therefore, stable operation is possible, and the life of the refrigeration cycle equipment is not adversely affected.

In particular, since the reduction in operating frequency F, F2 is stopped at the point where the slope of the increase in the high pressure side pressure becomes zero or less, that is, when the high pressure side pressure begins to decrease, it is possible to Optimal pressure release can always be performed regardless of response delay. That is, problems such as the high-pressure side pressure dropping too low do not occur.

Furthermore, since an oil return path such as an oil separator is provided for the compressors 1 and 2, refrigerating machine oil can be efficiently recovered.

In the above embodiment, only the abnormal increase in the high-pressure side pressure during the cooling operation was explained, but the same effect can be obtained with respect to the abnormal increase in the high-pressure side pressure during the heating operation.

Also, although we explained the case where the indoor unit is a king-sized unit,
In the case of more than three units, the same procedure will be carried out nJ
It is Noh.

In addition, the present invention is not limited to the second embodiment, and can be modified in various ways without changing the gist.

[Effects of the Invention] - As described above, according to the present invention, there are provided a means for detecting the pressure on the high pressure side of the refrigeration cycle, and a means for reducing the operating frequency of each of the compressors when the detected pressure exceeds a set value. , one stage for detecting the slope of the increase in the detected pressure, and a means for stopping the reduction in the operating frequency when the detected slope becomes less than a predetermined value, so that an abnormal increase in the pressure on the high pressure side is immediately suppressed and the system is always stable. We can provide air conditioners that can be operated.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a refrigeration cycle in one embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a control circuit in the same embodiment, and FIG. 3 is a diagram showing the high pressure side pressure and set value in the same embodiment. FIG. 4 is a diagram showing the change in operating frequency in the same embodiment, and FIG. 5 is a diagram schematically showing the configuration of a conventional air conditioner. A...Outdoor unit, B...Branch unit, C1+
C2, C3...Indoor unit, 1.2...Variable capacity compressor, 46...C: Kasensa, 50...Outdoor control section, 60...Multi control section, 70,80.90.・・・
Indoor control section. Between sections □ Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] An air conditioner comprising an outdoor unit having two variable capacity compressors and a plurality of indoor units, and controlling the number of operating compressors and the operating frequency of each compressor according to the required capacity of these indoor units. means for detecting high pressure side pressure; means for reducing the operating frequency of each compressor when the detected pressure exceeds a set value; and means for detecting the slope of increase in the detected pressure; An air conditioner comprising means for stopping the reduction in operating frequency when the operating frequency becomes lower.