JPH01203861A - Air conditioner - Google Patents

Abstract

PURPOSE:To perform a stable heating mode operation by performing a high pressure release in which the operating frequency of compressors is reduced when the high pressure side pressure exceeds a preset level, and adding the speed reduction of the outdoor fan as well as opening a release valve as needed. CONSTITUTION:The outdoor control section 50 monitors the detected pressure (high pressure side pressure) by a pressure sensor 46 while a heating mode operation is being performed, and causes the control in accordance with the detected pressure. That is, when the detected pressure exceeds a preset level into the M zone, the operating frequencies F1, F2 of compressors 1, 2 are caused to be reduced by certain steps down to the N zone which is below the preset level. If the detected pressure is down to P1 in the L zone, the operating frequencies F1, F2 are set at the commanded frequencies to resume a normal operation. When the operating frequencies F1, F2 are down to the minimum operating frequency Fmin, and the detected pressure reaches the set level, a release operation pattern is executed. That is, the speed of the outdoor fan 49 is made zero and a release valve 48 is opened so as to reduce the beat exchanging amount in the outdoor heat exchanger 6.

Description

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

(Prior Art) Generally, as this type of air conditioner, there is one shown in FIG.

A is an outdoor unit, and what are the two variable capacity compressors used for? Then, a branch unit B is connected to this outdoor unit A, and a plurality of indoor units CI are connected to the branch unit B.
, C2, and C3 are connected.

In other words, the indoor units C1*C2*C3 are
The required capacity corresponding to each air conditioning load is determined by the frequency setting signal f1. f2. Send to branch Uni-Soto B as f3.

Branching unit B receives the received frequency setting signals f,...
f2. The required capacity of each indoor unit/soto is determined from f3, and the frequency setting signal fo corresponding to the sum is sent to the outdoor unit A.
send to

The outdoor unit A controls the number of operating compressors and the operating frequency according to the frequency setting signal f 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, if the indoor and outdoor air conditions are both overloaded, the indoor unit capacity is small (one indoor unit with the minimum capacity is in operation), or the indoor air flow is small, the high pressure side pressure will increase. Abnormal rise. For example, this happens when starting up or when the number of operating indoor units decreases.

This invention was made in view of the circumstances described in 1-1.The purpose of this invention is to ensure stable operation at all times by suppressing abnormal rises in high-pressure side pressure to an optimal state. Our goal is to provide air conditioners that meet the needs of our customers.

[Structure of the Invention] (Means for Solving the Problems) Pressure detection means for detecting high pressure side pressure of a refrigeration cycle;
means for reducing the operating frequency of the compressor 6 until the detected pressure falls to a predetermined value when the detected pressure of the pressure detecting means exceeds a set value during cooling operation; means for reducing the operating frequency of each compressor when the detected pressure exceeds a set value until the detected pressure drops to a predetermined value, and means for reducing the speed of the outdoor fan in the outdoor unit in accordance with the detected pressure of the pressure detecting means at the time of this reduction. and

(Function) During cooling operation, when the high pressure side pressure of the refrigeration cycle exceeds the set value, the operating frequency of each compressor is reduced. During heating operation, if the high-pressure side pressure of the refrigeration cycle reaches the set value or higher,
The operating frequency of each compressor is reduced and, if necessary, the speed of the outdoor fan in the outdoor unit is reduced.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In the drawings, the same parts as in FIG. 6 are designated by the same reference numerals, and their explanations will be omitted.

As shown in FIG.
, 4 are connected in parallel through each of them.

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 a cooling expansion valve 12.22°32 and a heating cycle forming check valve 13.23°33, an indoor heat exchanger 14.
24.34, Gas side on-off valve (electromagnetic on-off valve) 15, 25,
35, the accumulator 10, etc. are successively connected to form a heat pump type refrigeration cycle.

The cooling expansion valves 12, 22.32 each have a temperature sensing tube 12a, 22a, 32a, and these temperature sensing tubes are attached to the gas side refrigerant piping of the indoor heat exchanger 14, 24.34, 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.

Then, the reference oil level positions of the cases of the compressors 1 and 2 are communicated with each other through an oil equalizing pipe 45, and the flow of lubricating oil between them is controlled.
+J Noh.

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

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

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

The control circuit is shown in FIG.

The outdoor unit yl.A includes an outdoor control section 50. The outdoor control unit 50 is composed of a microcomputer and its peripheral circuits, and is externally connected to a pressure sensor 46, a high pressure release valve 48, and an inverter circuit 51, 52 of the outdoor fan motor 49M1.

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 LM and 2M, respectively. It is something to do.

Branch unit B includes a multi-control unit 60. This multi-control unit 60 consists of a microcomputer and its peripheral circuits, and externally includes flow rate regulating valves 11, 21.3.
1 and on-off valves 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 1-, Figures 3 to 5
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 unit 7° of the indoor unit C1 calculates the difference between the temperature detected by the indoor temperature sensor 72 and the set temperature determined by the operation unit 71, and sets the frequency corresponding to the temperature difference. The signal f1 is transferred to the multi-control unit 60 as the required cooling capacity.

Similarly, the indoor control section 80.9 of the indoor units C2 and C3
0 is also the frequency setting signal f2. f3 is transferred 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 section 50.

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

The number of operating compressors 1.2 and the 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 two compressors @1 and 2 as the total required cooling capacity increases.

Note that the multi-control unit 60 controls the indoor units C1+C2,
The opening degrees of the corresponding flow rate regulating valves 11, 21, and 31 are controlled according to the required cooling capacity of the indoor heat exchanger 14.
, 24 and 34 to maintain a constant degree of refrigerant superheat.

By the way, during this cooling operation, the outdoor control unit 50 monitors the detected pressure Pd (high pressure side pressure) of the pressure sensor 46.
Controls shown in FIGS. 3 and 5 are performed in accordance with the detected pressure Pd.

That is, when the detected pressure Pd exceeds the set value
Decrease F2 by a predetermined step.

When the detected pressure Pd falls to the N region, the operating frequencies Fl and F2 at that time are maintained. Then, after 15 minutes, if the detected pressure Pd falls to a range below P1, the operating frequency F
1. Set F2 to the command frequency and return to normal operation.

However, if the detected pressure Pd is in the N range after 15 minutes, then N
Detected pressure Pd at the highest possible point in the area (near P2)
Increase or decrease the operating frequency F1°F2 by one step so that the In this case, by keeping the detected pressure Pd as high as possible in the N region, the lack of capacity is alleviated as much as possible.

While the detected pressure Pd remains in the M region or the N region, the shaft operating frequency F,, F2 decreases to the minimum operating frequency Fmin, and when the detected pressure Pd reaches P4, the operating frequency F1.
Let F2 be zero. That is, the operation of the compressors 1 and 2 is stopped to suppress an abnormal increase in the pressure on the high pressure side.

When 14 minutes have elapsed since the operation was stopped, the compressor 1.2 is started for 11 hours, but this time the set value X is set to be 1 kg/e-G lower (P2-1). If the operation is stopped even in this state, the set value X is further set lower by 1 ksr/cd G (P2-2). In the event of a severe rise that results in a shutdown despite these two pressure releases, the current situation will continue and high pressure protection will depend on the activation of a high pressure switch (not shown) (if the high pressure switch is activated, a complete shutdown will occur). ).

In this way, when the high pressure side pressure becomes equal to or higher than the set value X, the operating frequency F1 of the compressor 1.2 is changed. By performing high-pressure release to reduce F2, it is possible to suppress an abnormal increase in the pressure on the high-pressure side, and stable cooling operation is possible. Furthermore, the life of the refrigeration cycle equipment is not adversely affected.

Moreover, since the set value do not have.

On the other hand, during the heating operation, the number of operating compressors 1 and 2 and the operating frequency are controlled according to the required heating capacity of the indoor units C, , C2 and C3.

During this heating operation, the outdoor control section 50 monitors the detected pressure Pd (high pressure side pressure) of the pressure sensor 46, and performs the control shown in FIGS. 4 and 5 according to the detected pressure Pd.

That is, when the detected pressure Pd exceeds the set value ．．
Decrease F2 by a predetermined step.

When the detected pressure Pd falls to the N region, the operating frequencies F, , F2 at that time are maintained. Then, [After 5 minutes, if the detected pressure Pd falls to the L region below P1, the operating frequency F
Set B and F2 to the command frequency and return to normal operation.

However, if the detected pressure Pd is in the N range after 15 minutes, then N
Detected pressure Pd at the highest possible point in the area (near P2)
The operating frequency F1+F2 is increased or decreased by one step so that the In this case, by keeping the detected pressure Pd as high as possible in the N region, the lack of capacity is alleviated as much as possible.

While the detected pressure Pd remains in the M region or N region, the operating frequency F1. F2 drops to the lowest operating frequency F girl,
Furthermore, when the detected pressure Pd reaches the set value Y (initial value P3), the release operation pattern (2) shown in the table below is executed. That is, the speed of the outdoor fan 49 is set to zero (operation off), the release valve 48 is opened, and the number of heat exchangers in the outdoor heat exchanger 6 is reduced. Then, this release operation pattern (2) is executed for 2 minutes, and then the release operation pattern (V) is executed.

When the detected pressure Pd reaches P4 despite execution of the release operation patterns Vl and V, the operation frequency FI,
F2 is set to zero and the operation of compressors 1 and 2 is stopped.

After 14 minutes have passed since the operation stopped, compressors 1 and 2 are restarted, but this time the set value X is set to 1 kg/cd G.
Set low (P: 1-1) and set value Y to 1 kg/
Set to J G low (P3 1). If the operation is stopped in this state, increase the set value X by an additional 1kg/c+#
G is set to low (P2-2), and the setting value Y is further increased by 1k.
g/cd Set to G low (P32). In the event of a severe increase in pressure that does not allow the pressure to be released twice and results in a shutdown, the current situation will continue and high pressure protection will depend on the activation of a high pressure switch (not shown) (if the high pressure switch is activated, (total stop 1-).

When the detected pressure Pd falls to the N range below P2 by executing the release operation patterns Vl and V, the operating frequency F1. F2 and release operation pattern V are maintained. Thereafter, a release operation pattern is appropriately selected according to changes in the detected pressure Pd, and an optimal high-pressure release is executed.

In this way, when the high-pressure side pressure becomes equal to or higher than the set value By adding the opening, abnormal rise in pressure on the high pressure side can be reliably suppressed to an optimum state, and stable heating operation can be performed.

Moreover, since the set value X (and Y) is lowered sequentially, the -1,
It is possible to suppress the rise without overrun, and there is no problem of the high voltage switch operating every time.

Further, since an oil passage such as an oil separator is provided to the compressor 1.2, refrigerating machine oil can be efficiently recovered regardless of whether the compressor is used for cooling or heating.

In the above embodiments, the case where there are two indoor units has been described, but it is also possible to implement the case with more or three indoor units.

In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without changing the gist.

[Effects of the Invention] As described above, according to the present invention, there is provided a pressure detection means for detecting the pressure on the high pressure side of the refrigeration cycle, and when the detected pressure of the pressure detection means exceeds a set value during cooling operation, the detected pressure is detected. means for reducing the operating frequency of each compressor until the pressure drops to a predetermined value; and a means for reducing the operating frequency of each compressor until the detected pressure of the pressure detection means exceeds a set value during heating operation, and operating each compressor until the detected pressure falls to a predetermined value. By providing a means for reducing the frequency and a means for reducing the speed of the outdoor fan in the outdoor unit according to the pressure detected by the first pressure detection stage at the time of this reduction, it is possible to prevent abnormalities in the high pressure side pressure. We can provide an air conditioner that maintains optimal conditions and always operates stably.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a control circuit in one embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a refrigeration cycle in the same embodiment, and FIG. 3 is a diagram explaining the operation of the cooling operation in the same embodiment. FIG. 4 is a flowchart for explaining the operation of heating operation in the same embodiment.
FIG. 5 is a diagram showing the relationship between the high pressure side pressure and the set value in the same embodiment, and FIG. 6 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... Pressure sensor, 49... Outdoor fan, 50... Outdoor control unit, 60... Multi control unit, 7
0°80.90...Indoor control unit. Applicant's agent Patent attorney Takehiko Suzue

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. pressure detection means for detecting high-pressure side pressure; and means for reducing the operating frequency of each compressor when the pressure detected by the pressure detection means exceeds a set value during cooling operation until the detected pressure falls to a predetermined value; During heating operation, when the pressure detected by the pressure detection means exceeds a set value, means for reducing the operating frequency of each compressor until the detected pressure falls to a predetermined value; and at the time of this reduction, the pressure detected by the pressure detection means An air conditioner comprising means for reducing the speed of an outdoor fan in the outdoor unit accordingly.