JPH0221729Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a refrigeration cycle device equipped with a variable capacity compressor using an inverter circuit.

[Technical background of the invention and its problems]

Generally, in this type of refrigeration cycle device, there is a strong demand for an expansion of the approximate proportional capacity variable range. As a way to deal with this,
It is conceivable to adopt a large capacity variable capacity compressor.

However, there is a problem in that in order to employ a large capacity variable capacity compressor, a large capacity inverter circuit must be used. That is, it is difficult to increase the capacity of an inverter circuit due to technical problems such as the current capacity of the power transistor in the inverter circuit.

Furthermore, even if a large-capacity variable-capacity compressor could be adopted, this would result in a significant change in the refrigerant flow rate in the refrigeration cycle. There is a danger of accumulation, and in the end, it is impossible to expand the approximate proportional capacity variable range.

[Purpose of invention]

This idea was devised in view of the above circumstances, and its purpose was to eliminate the need for a large capacity variable capacity compressor, and to achieve approximate proportional capacity while using a small capacity inverter circuit. An object of the present invention is to provide a refrigeration cycle device that allows expansion of the variable range.

[Summary of the idea]

This idea includes a plurality of refrigeration cycles each having a variable capacity compressor, and depending on the size of the load, one of the compressors is driven by an inverter circuit, and the other compressors are driven. It is either driven by the power supply voltage or stopped.

[Example of idea]

An embodiment of this invention will be described below with reference to the drawings. In this case, the application form to an air conditioner will be described.

In FIG. 1, A is a variable capacity compressor, and this compressor A includes a four-way valve 11, an outdoor heat exchanger 12,
The parallel body of the heating expansion valve 13 and the check valve 14, the parallel body of the cooling expansion valve 15 and the check valve 16, and the indoor heat exchanger 17 are sequentially connected, and thereby the first heat pump type refrigeration cycle is started. configured. B is a variable capacity compressor with a smaller capacity than the compressor A, and this compressor B is equipped with a four-way valve 21, an outdoor heat exchanger 22,
A parallel body of a heating expansion valve 23 and a check valve 24, a parallel body of a cooling expansion valve 25 and a check valve 26, and an indoor heat exchanger 27 are sequentially connected to form a second heat pump type refrigeration cycle. . The compressors A and B have built-in drive motors Am and Bm, respectively.

On the other hand, 31 is a three-phase AC power supply, and the input end of an inverter circuit 32 is connected to the R, S, and T phases of this power supply 31. This inverter circuit 32 converts the power supply voltage into an alternating current voltage of a predetermined frequency and outputs it, and may have a capacity of 70% or less of a conventional inverter circuit for reasons described later. Thus, an energizing path is formed between the output end of the inverter circuit 32 and the drive motor Am via one contact of each of the changeover switches 33a, 33b, and 33c. Output end of inverter circuit 32 and drive motor
There are selector switches 34a, 34b, 3 between
An energizing path is formed through each one of the contacts 4c. That is, the changeover switches 33a, 33
b, 33c, 34a, 34b, and 34c are switch means for selectively forming an energizing path from the inverter circuit 32 to any one of the drive motors Am and Bm. Further, switches 35a, 35b, 35c and a changeover switch 33 are connected between the R, S, and T phases of the power source 31 and the drive motor Am.
An energizing path is formed through the other contacts of contacts a, 33b, and 33c in series. R of power supply 31,
Switches 35a, 35b, 35c and a changeover switch 34 are installed between the S and T phases and the drive motor Bm.
An energizing path is formed through the other contacts of contacts a, 34b, and 34c in series. That is, the changeover switches 33a, 33b, 33c, 34a, 34
b, 34c and switches 35a, 35b, 35
c, the power supply 31 drives the drive motors Am and Bm.
It constitutes a switch means for selectively forming an energizing path for.

Furthermore, 36 is a control unit, and a functional means for detecting the size of the load based on the difference between the indoor temperature detected by the temperature sensor 37 and the set temperature of the temperature setting device 38;
Functional means for controlling the output voltage frequency (drive voltage frequency) of the inverter circuit 32 according to the detected load size, changeover switches 33a, 33b, 33c34 according to the detected load size.
a, 34b, 34c and switch 3
5a, 35b, and 35c are turned on and off, one of the driving motors Am and Bm is driven by an inverter, and the remaining driving motors are selectively driven by a power supply voltage.

Next, the operation in the above configuration will be explained.

Assume that cooling operation is currently being performed. At this time, if the difference between the indoor temperature and the set temperature is small and the load is small, the control section 36 switches the changeover switch 33a,
33b, 33c to the power supply 31 side, changeover switches 34a, 34b, 34c to the inverter circuit 32 side, and switch 35.
Turn off a, 35b, and 35c. That is, only the current-carrying path from the inverter circuit 32 to the drive motor Bm is formed. In this way, the drive motor Bm
The inverter circuit 2 operates at a rotational speed corresponding to the drive voltage frequency (which changes as the load fluctuates) output from the inverter circuit 2. In other words, only the capacity variable operation of the compressor B is performed. In this case, a cooling capacity within the range shown by the intersecting dashed lines in FIG. 2 can be obtained.

If the difference between the indoor temperature and the set temperature is not so small and the load is moderate, the control section 36 switches the changeover switches 33a, 33b, 33c to the inverter circuit 32 side, and also switches the changeover switches 34a, 34b, Switch 34c to power supply 31 side,
Furthermore, switches 35a, 35b, and 35c are turned off. That is, only the current-carrying path from the inverter circuit 32 to the drive motor Am is formed. In this way, the drive motor Am operates at a rotational speed that corresponds to the drive voltage frequency (which changes as the load changes) output from the inverter circuit 32. In other words, only the capacity variable operation of the compressor A is performed. In this case, a cooling capacity within the range indicated by dots in FIG. 2 can be obtained.

If the difference between the room temperature and the set temperature is large and the load is large, the control section 36 switches the changeover switches 33a, 3
3b, 33c to the inverter circuit 32 side, and changeover switches 34a, 34b, 34c.
switch to the power supply 31 side, and then switch 35a,
Turn on 35b and 35c. In other words, a current path is formed from the inverter circuit 32 to the drive motor Am, and a current path is formed from the power supply 31 to the drive motor Am.
An energizing path to Bm is formed. In this way, the drive motor Am operates at a rotational speed corresponding to the drive voltage frequency (which changes as the load fluctuates) output from the inverter circuit 32, and the drive motor Bm operates at the power supply voltage. In other words, compressor A is operated with variable capacity, and compressor B is operated with constant capacity. In this case, the second
A cooling capacity within the shaded range in the figure is obtained.

In this way, the first and second heat pump refrigeration cycles each having variable capacity compressors A and B are provided, and the compressors A and B are adjusted according to the size of the load.
Since one side of B is driven by the inverter circuit 2 and the other is driven by the power supply voltage or stopped, it is possible to obtain a wide approximate proportional capacity variable range that is more than 30% wider than before. can.
Moreover, there is an advantage that the inverter circuit 32 may have a capacity of 70% or less of that of conventionally used inverter circuits.

In the above embodiment, the compressors A and B have different capacities, but they may have the same capacity. Further, although the approximate proportional ability variable range is continuous from the lower limit to the upper limit, an intermittent area may be provided in the middle. Furthermore, the refrigeration cycle is not limited to a heat pump type, and can be implemented in a similar manner even when used exclusively for cooling, and can be similarly implemented when the heat exchanger is a water heat exchanger. Moreover, although the application to an air conditioner has been described, it is also applicable to refrigeration equipment such as a refrigerator.

[Effect of idea]

As mentioned above, according to this invention, there is no need to adopt a large capacity variable capacity compressor, and a refrigeration cycle device that can expand the approximate proportional capacity variable range is created using a small capacity inverter circuit. Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of this invention, and FIG. 2 is a diagram for explaining the operation of the embodiment. A, B...variable capacity compressor, Am, Bm...
Drive motor, 31... Three-phase AC power supply, 32...
Inverter circuit, 33a, 33b, 33c, 34
a, 34b, 34c...changeover switch, 35a,
35b, 35c...Switch, 36...Control unit.

Claims (1)

[Scope of utility model registration request] A plurality of refrigeration cycles each having a variable capacity compressor, one inverter circuit that converts power supply voltage into an alternating current voltage of a predetermined frequency and outputs it, and one of the drive motors for each of the compressors from this inverter circuit. switch means for selectively forming a conduction path from the power supply to the drive motor of each of the compressors; and a switch means for selectively forming a conduction path from the power supply to the drive motor of each of the compressors, and an output voltage of the inverter circuit according to the size of the load. A control means for controlling the frequency and the respective switch means are controlled according to the size of the load to drive one of the drive motors using an inverter and to selectively drive the remaining drive motors with a power supply voltage. A refrigeration cycle device comprising: a control means for controlling the refrigeration cycle;