JPS6294749A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent a simultaneous defrosting operation due to a plurality of freezing-cycle operations and prevent the space heating ability from lowering due to the simultaneous defrosting operation by providing a controller for making the defrosting operation by other freezing-cycle machines to be at stand-by state when at least one freezing-cycle machine is in a defrosting operation. CONSTITUTION:An outdoor controller 20 receives a defrosting signal from a defrosting sensor 18A of a first freezing cycle A, at first, whether a second freezing cycle B is in a defrosting operation is judged. In a case where a second freezing cycle B is in a defrosting operation, the changeover of the first freezing cycle A to be subjected to defrosting operation is stopped, and the defrosting operation is put at stand-by state. While the defrosting operation is caused to wait, the space heating operation is continued. On the other hand, in a case where the second freezing cycle B is not in the defrosting operation, an outdoor controller 20 causes a power to be supplied to a four-way valve B of the first freezing cycle A, and changes the mode of operation to the defrosting operation.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an air conditioner provided with a plurality of refrigeration cycles,
In particular, the present invention relates to an air conditioner that prevents simultaneous defrosting operations using multiple refrigeration cycles.

[Technical background of the invention]

Conventionally, the refrigeration cycle of this type of air conditioner is constructed as shown in FIG. 11, in which a first refrigeration cycle A is independently provided with a second frozen bone nicle B.

The first and second refrigeration cycles A and B are compressor IA'
, 1B1 four-way valve 2A, 2B, indoor heat exchanger 3A, 3B
, cooling defrosting diaphragm devices 4A, 4B and check valves 5A, 5
A parallel circuit of B, a parallel circuit of heating throttle devices 6A, 6Bj3 and check valves 7A, 7B, and an outdoor heat exchanger 8A, 8B are sequentially connected in an annular manner with refrigerant pipes 9A, 9B. By switching the valves 2A and 2B, the indoor cooling room and the outdoor heat exchangers 8A and 8B are defrosted.

The parallel circuit of the indoor heat exchangers 3A, 3B, cooling snow removal throttling devices 4A, 4B, and check valves 5A, 5B are housed together with the indoor fan 10 in one indoor unit 11. The above refrigeration cycle components are housed in the outdoor unit together with the outdoor fans 12A and 12B.
'+7ru.

As shown in FIG. 12, the compression 1fiIA to the first refrigeration cycle is connected to an inverter unit @13 and configured to have variable capacity, and is operated as the main engine of the air conditioner or for fine adjustment.

On the other hand, the compressor 1B of the second refrigeration cycle 8 has a constant capacity, and is operated as a standby for the first refrigeration cycle A to increase or decrease the capacity by one rank.

The four-way valves 2A and 2B of both refrigeration cycles A and B and the outdoor fans 12A and 12B are A and 8 outdoor controllers 14A and 14B.
A.

8 indoor side controllers 14A and 14B are one indoor side controller 2
It is electrically connected to the II unit 15.

The indoor controller 15 reads the temperature detected by the temperature sensor 16 and the set value of the setting switch 17, and controls the operation of the indoor fan 10, as well as the controllers A and B outdoor controllers 14A, 14.
An operation signal 158 is output to B to control the operation of both refrigeration cycles A and B.

In addition, the solid line arrow in FIG. 11 indicates the refrigerant flow direction during cooling/defrosting operation, and the broken line arrow indicates the refrigerant flow direction during heating operation.

[Problems with background technology]

However, the conventional A, 8 outdoor system tllZ14A,
14B inputs the signals from the defrosting sensors 18A and 18B of the first and second refrigeration cycles A and B respectively, independently determines the defrosting start conditions, and controls the defrosting operation for each refrigeration cycle. Control was performed so that cycles A and B were performed independently.

Therefore, the conventional A, 8 outdoor controllers 14A, 14
In case B, there were cases where both freezing cycle A and B were operated to defrost at the same time. Defrosting operation is tJJU'D; the flow direction of the refrigerant during operation is reversed, so to speak, cooling operation is performed.
Both refrigeration cycles A during heating operation.

If the defrosting operation was performed at the same time by B, there was a problem that the room would be cooled and the indoor humidity would be lowered.

Furthermore, when one of the refrigeration cycles A or B switches to defrosting operation, there is a drawback that the heating operation of the other refrigeration cycle is stopped until the defrosting operation is completed.

(Object of the Invention) The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an air conditioner that prevents simultaneous defrosting operations using a plurality of refrigeration cycles.

[Summary of the invention]

The present invention was made by focusing on the problem of conventional air conditioners in that a plurality of indoor controllers individually operated a plurality of refrigeration cycles. An air conditioner having a plurality of refrigeration cycles is characterized in that it is provided with a controller that makes defrosting operations of other refrigeration cycles stand by when at least one refrigeration cycle is in defrosting operation.

(Embodiments of the Invention) Hereinafter, embodiments of the present invention will be described with reference to the drawings.In the drawings, parts common to Figs. 11 and 12 are designated by the same reference numerals, and the overlapping The explanation of the parts will be omitted.

FIG. 1 shows a control system according to an embodiment of the present invention in a block diagram, and reference numeral 20 in the figure indicates the operation signal 158 from the indoor controller 15 for both the first and second refrigeration cycles A. , B
It controls the operation of compressors IA and IB of both refrigeration cycles A and B.

It is electrically connected to the four-way valves 2A, 2B, the outdoor fans 12A, 12B1, and the defrosting sensors 18A, 18B. however,
The compression 1ffllA of the first refrigeration cycle A is equipped with an inverter device 13 and is configured to have variable capacity.

Indoor control i! 1:15 has a built-in program that instructs the operation pattern of both compressors IA and IB shown in Fig. 3 (a), and since compression 11A of the first refrigeration cycle A is of variable capacity type, this compression Operate machine 1A as the main machine or for fine adjustment.

That is, when the instruction frequency of the operation signal 15S from the indoor controller 15 is the lowest frequency f min, the compressor 1
The operation of cycle A is started independently, and heating operation is performed using only the first refrigeration cycle A.

Also, the ON frequency f where the instruction frequency of the driving signal @15S is higher than the above-mentioned minimum frequency. When N is reached, the outdoor subil
The compressor 20 starts the operation of the compressor 11B, and the heating operations of both the first and second refrigeration cycles A and B are performed in parallel. As a result, the capacity of the air conditioner as a whole increases by one rank, as shown in FIG. 3(1)).

When the command frequency of the operation signal 15S is equal to or lower than the OFF frequency f, the operation of the constant capacity compressor 1BFF is stopped, the heating operation of the second refrigeration cycle B is stopped, and only the first refrigeration cycle A is stopped. Drive alone.

As a result, the performance of the air conditioner as a whole decreases by one rank, as shown in FIG. 3(b).

In this way, the first and second refrigeration cycles A and B have different frosting conditions on the outdoor heat exchangers during heating operation due to differences in operating time and operating capacity, and are switched to defrosting operation. The timing of sleeping is often different.

However, since the defrosting operation timing may coincide in both refrigeration cycles A and B, the outdoor controller 20 has a built-in control program shown in the flowchart of FIG. 2 to prevent simultaneous defrosting operations. control.

However, when the outdoor controller 20 inputs the defrosting signal from the defrosting sensor lt18A to the first refrigeration cycle, it first checks whether the second refrigeration cycle B is already in defrosting operation or not. Decide whether or not. When this is YES1, that is, when the second refrigeration cycle B is in the defrosting operation, the switching to the defrosting operation of the first refrigeration cycle A is stopped, and the defrosting operation is put on standby. Thereby, simultaneous defrosting operation by both refrigeration cycles A and B can be prevented. The heating operation is continued while the defrosting operation is on standby. On the other hand, if it is ON, that is, the second
When the refrigeration cycle B is not in defrosting operation, the outdoor controller 20 energizes the four-way valve 2A of the first refrigeration cycle A to switch to the defrosting operation.

On the contrary, when the outdoor side TXT device 20 inputs the defrosting signal of the defrosting sensor 18B of the second refrigeration cycle B, first, the first refrigeration cycle A is already in the defrosting operation. If the answer is YES, that is, the defrosting operation is in progress, the defrosting operation of the second refrigeration cycle B is put on standby. Thereby, simultaneous defrosting operation by both refrigeration cycles A and B can be prevented. Further, when only the first refrigeration cycle A is switched to the defrosting operation during heating operation, the second refrigeration cycle B may start heating operation.

The compression 1fi1A inverter device 13 of the first refrigeration cycle A is configured as shown in FIG. The inverter section 24 is connected to the inverter section 24 to convert direct current into three-phase arbitrary variable frequency alternating current.

The DC link section 23 has a capacitor C connected in parallel to the connection point of the two reactors L and L2 connected in series, and a transistor Q connected in series to the reactor L1.
A capacitor C2 is connected in parallel to the capacitor C2 via a diode D, and an inverter section 24 is connected to both ends of the capacitor C2.

The transistor Q is controlled ON-OFF by the control circuit 25, and the DC voltage is controlled according to the output frequency from the inverter section 24.
The DC voltage of the link section 23 is controlled. That is, the control circuit 25 sets the required frequency of the output from the inverter section 24 as a set frequency as shown in the voltage/frequency pattern of FIG. 6, and turns the transistor Q ON-OFF according to the program shown in the flowchart of FIG. control.

That is, when the output frequency f from the inverter section 24 is in a frequency range lower than the set frequency f1, pulse amplitude modulation (RAM) control is performed to vary the DC voltage input to the inverter section 24.

Furthermore, when the output frequency f from the inverter section 24 is in a high frequency region higher than the set frequency, the output voltage is constant, so the control circuit 25 performs control (Pf''=1 control) to reduce power harmonics. ON-OFF control of transistor Q is performed so as to perform I).

Therefore, according to this inverter device 13, pulse amplitude modulation control is performed before the inverter section 24, so that
It is possible to reduce Jli noise caused by switching of the inverter section 24 and XITl of the motor 26.

The voltage and current waveforms of each part of this inverter device 13 are as shown in FIG. The latter current waveform i has harmonics with a peak-to-peak value Δi superimposed thereon.

In addition, (C) and (d) are reactors L2 and Ll
The current waveforms flowing through the reactor L are shown.
Although the current is full-wave rectified, a current with equal harmonics Δi superimposed on the AC power source 21 side flows through the reactor L1, and a current containing harmonics with expanded amplitude flows through the reactor L1.

Furthermore, (e) represents the waveform of the voltage across the capacitor C2.

In FIG. 8, a current detection circuit 27 is provided in the DC link section 23 of the inverter device 13 to detect the current flowing into the inverter section 24, and the motor current value of the compressor 1A is detected from the detected current waveform. It shows the configuration.

The current detection circuit 27 has a current sensor 28 provided in the DC link section 23, and the current sensor 28 detects the triangular wave current 'DC' shown in FIG. This triangular wave detection current I. indicates a physical quantity whose peak value corresponds to the motor current value, so by detecting this peak value, the motor current, ie,
The load torque of the motor 26 can be detected. For example, if the load torque of the motor 26 is constant and the rotation speed of the motor 26 is increased, the DC average current value shown by the broken line in FIG. 9 only increases, and the peak value does not change.

Therefore, the current detection circuit 27 detects the detection current I as shown in FIG. 0 is passed through an integrating circuit with a large time constant to detect the average DC current value, and is passed through an integrating circuit with a small time constant to detect the motor current value at the peak value. For this reason, the motor current value can be detected by the current detection circuit 27 having a simple configuration, and moreover, it is possible to accurately detect the motor current value without being adversely affected by the parallel non-parallel currents on the output side of the inverter section 24. can.

Further, the frequency of the voltage/frequency (V/f) command output from the control circuit (CPU) 29 may be controlled according to the motor current value detected by the current detection circuit 27.

In addition, in FIG. 8, reference numeral 30 indicates V/f from the control circuit 29.
This is a base drive circuit that drives a power transistor (not shown) of the inverter unit 24 based on a command.

(Effects of the Invention) As explained above, in an air conditioner having a plurality of refrigeration cycles, when at least one refrigeration cycle is in defrosting operation, the other refrigeration cycles are put on standby for defrosting operation. A container was set up.

Therefore, according to the present invention, it is possible to prevent simultaneous defrosting operations using a plurality of refrigeration cycles, and to prevent a decrease in heating capacity due to simultaneous defrosting operations.

As a result, the defrosting operation time can be shortened.

Furthermore, when the refrigeration cycle that is on standby for defrosting operation is controlled to heating operation, heating operation is always continued, so that comfortable heating operation can be performed.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a control system in an embodiment of an air conditioner according to the present invention, and Fig. 2 is an outdoor division shown in Fig. 1.
A flowchart of a program built into Dn to prevent simultaneous defrosting operations using multiple refrigeration cycles;
3-1=-1 is a graph showing the operating state of the embodiment shown in FIG. 1 and the capacity during each operation divided by current ÷, FIG. 4 is a circuit diagram of the inverter device shown in FIG. Figures (a) to (e) are dimensional waveform diagrams of the voltage and current waveforms of each part of the inverter shown in Figure 1, and Figure 6 shows the operating state of the control circuit 25 of the inverter shown in Figure 4. Graph, 7th
The figure is a flowchart of a program built into the control circuit 25 of the inverter device shown in FIG. 4, and FIG. 8 is a block diagram showing the configuration when the inverter device shown in FIG. 1 is provided with a current detection circuit for detecting motor current. 9 is a waveform diagram of the current detected by the current detection circuit 27 shown in FIG. 8, and FIG. 10 is a schematic diagram for explaining the action of the integrating circuit of the current detection circuit (not shown in FIG. 8). , FIG. 11 is a refrigeration cycle diagram of a conventional air conditioner, and FIG. 12 is a plot diagram of a control system of a conventional air conditioner. 20... Outdoor side auxiliary unit, 22... Converter section, 23... DC link section, 24... Inverter section,
25... Control circuit, 28... Current detection circuit. Representative Patent Attorney Nori Chika Ken Yudo Kata Yama Yuki Futsuri l Zucha 2 G Kei 4 Sono 5 Figure No. 6 Vice Graduate '7 Figure 6 Figure 6 Certain io Seki

Claims (1)

[Claims] 1. In an air conditioner having a plurality of refrigeration cycles, when at least one refrigeration cycle is in defrosting operation, a controller is provided that makes the defrosting operation of other refrigeration cycles stand by. Characteristic air conditioner. 2. The air conditioner according to claim 1, wherein the controller controls the refrigeration cycle, which is waiting for defrosting operation, to heating operation during that time.