JPH0328279Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] This invention relates to a variable capacity air conditioner that has two mutually independent refrigeration cycles in one unit, and specifically includes a defrosting control device that operates during heating operation. This is an improved version.

[Technical background of the invention] Conventionally, a variable capacity air conditioner having two mutually independent refrigeration cycles in one unit has one refrigeration cycle formed by an air-cooled heat pump having a compressor with constant capacity, and the other refrigeration cycle formed by an air-cooled heat pump having a compressor with constant capacity. The refrigeration cycle is formed by an air-cooled heat pump with a variable capacity compressor. When the other refrigeration cycle on the compressor side, which has variable capacity, is performing heating operation with its capacity saved by capacity control, one refrigeration cycle on the compressor side, whose capacity is constant, is in defrosting operation. Even when the compressor was turned on, the variable capacity compressor continued to operate with its capacity saved.

[Problems with the Background Art] However, in the above-mentioned conventional variable capacity air conditioner, even when the compressor side with a constant capacity enters defrosting operation, the compressor side with a variable capacity remains in a state where the capacity is saved. This resulted in the following drawbacks.

1 Cold air blows out from the indoor unit during defrosting operation.

2. In order to prevent cold air from blowing out, the indoor fan motor was stopped, but with this method the defrosting time was extremely long and the heating efficiency was poor.

[Purpose of the invention] This invention was made in consideration of the above circumstances, and it prevents cold air from blowing out from the indoor unit without stopping the indoor fan motor during defrosting operation, thereby achieving high heating efficiency. The purpose of the present invention is to provide a defrosting control device for a variable air conditioner.

[Summary of the invention] In order to achieve the above object, this invention provides two independent refrigeration cycles consisting of a compressor, a four-way valve, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger in one unit, and A variable capacity air conditioner that combines both indoor heat exchangers, uses a constant capacity compressor in one refrigeration cycle, uses a variable capacity compressor in the other refrigeration cycle, and operates both refrigeration cycles by a control system. , a sensor detects frost formation on the indoor heat exchanger during heating operation, and when the sensor detects frost formation on the refrigeration cycle side that has a compressor with constant capacity, the four-way valve of that cycle is set to the defrost cycle. The above control system is equipped with an operation command means that gives a defrosting operation command to switch, maintains the operation of the indoor fan motor, and gives a maximum capacity operation command to a variable capacity compressor. The cold air blown out from the indoor unit on the refrigeration cycle side that is in the refrigeration cycle can be offset by the warm air blown out from the indoor unit on the refrigeration cycle side that has entered maximum capacity operation, preventing cold air from blowing out from the indoor unit and reducing heating efficiency. I tried not to do that.

[Embodiment of the invention] An embodiment of the invention will be described below based on FIGS. 1 to 4.

Figure 1 shows two independent refrigeration cycles.
A variable capacity air conditioner is provided within the unit, and one refrigeration cycle A is formed by a heat pump having a constant capacity compressor 1, and the other refrigeration cycle B is formed by a heat pump having a compressor 2 whose capacity is variable. The refrigeration cycle configuration diagram is shown below.
In the figure, C is the indoor side, D is the outdoor side, 3 is a common indoor heat exchanger, 4a and 4b are expansion valves as pressure reducing devices, 5a and 5b are check valves, and 6a and 6b are outdoor heat exchangers. The exchangers 7a and 7b are four-way valves, and 8a and 8b are frost sensors provided on each outdoor heat exchanger 6a and 6b to detect frost formation on the outdoor heat exchanger. The subscript a of the symbol means that it is in the refrigeration cycle A on the compressor 1 side, whose capacity is constant, and the subscript b means that it is in the refrigeration cycle B on the compressor 2 side, whose capacity is variable. The outputs of the sensors 8a and 8b are the refrigeration cycle A.
and B are connected to a control circuit 9 that controls the operation of the motors. In addition, in the figure, a solid line arrow indicates a refrigeration cycle, and a dotted line arrow indicates a heating cycle.

FIG. 2 is a block diagram showing a schematic configuration of the control circuit 9. This control circuit 9 sends an operation command a to a compressor 2 whose capacity is variable based on a signal d from a control panel 10. or fan motor/
The compressor 2 and the four-way valve 7a have a known circuit configuration (not shown) that gives control commands b and c to the four-way valves 7a and 7b, respectively, and whose capacity can be varied based on the output signal e from the frost sensor 8. , 7b is provided with an operation command circuit having the following configuration for performing defrosting control by giving operation commands to the motors 7b and 7b.

The above operation command circuit includes the frost formation sensor 8 during heating operation.
A defrosting operation command that determines whether or not frost has formed on the outdoor heat exchanger 6a based on the output signal e from the , and when frost formation is detected, switches the four-way valve 7a to change to the defrosting cycle that is cooling operation. It has a frost formation determination circuit 11 which applies the signal f to the four-way valve 7a and outputs a frost formation detection signal g. This frost formation judgment circuit 11 is connected to a comparison circuit 12, and the comparison circuit 12 is activated when receiving the frost formation detection signal g. By its operation, this comparison circuit 12 compares the capacity operation command i given to the variable capacity compressor 2 with the maximum capacity operation command h, and when the capacity operation command i does not reach the maximum capacity operation command It has a function of forcibly switching the capacity operation command i of the compressor 2 whose capacity is variable to the maximum capacity operation command h.

Now, in the above configuration, when the refrigeration cycle B on the compressor 2 side with variable capacity is currently in heating operation with its capacity saved by the operation command a, the refrigeration cycle B on the compressor 1 side with a constant capacity is currently in heating operation. When the outdoor heat exchanger 6a on the side constituting the refrigeration cycle A becomes frosted, this frosting information is converted into an electric signal by the frosting sensor 8a and input to the operation command circuit, and the frosting judgment circuit 11 Frost formation is detected on the heat exchanger 6a, and from this, a defrosting operation command f is sent to the four-way valve 7a.
The frost formation detection signal g is given to the comparator circuit 12 at the same time.
Therefore, the refrigeration cycle A on the compressor 1 side, which has a constant capacity, enters the defrosting cycle, which is essentially a cooling operation, and at the same time, the comparison circuit 1 receives the frost detection signal g.
2, the variable capacity compressor 2 on the other refrigeration cycle B side is forcibly given a maximum capacity operation command and switched from save operation to maximum capacity operation.

Therefore, the indoor heat exchanger 3 on the indoor unit side C
In this case, cooling by refrigeration cycle A, which has entered defrosting operation, and heating by refrigeration cycle B, which has switched to maximum capacity operation, are performed simultaneously, and the heating by refrigeration cycle B, which has a large capacity, exceeds the cooling by refrigeration cycle A. Become. As a result, as shown in Figure 4, even when one of the refrigeration cycles entered the defrosting operation, the other refrigeration cycle was still in the save operation, so the blowout temperature fell below the suction temperature n due to the defrosting operation. Compared to the conventional device 1, the device of this embodiment can make the blowing temperature from the indoor unit C higher than the suction temperature n, that is, the room temperature, as shown by m. For this purpose, an indoor fan motor (not shown)
There is no need to stop the outdoor heat exchanger 6a.
Defrosting time can be shortened as much as possible.

FIG. 5 shows a modification of the embodiment shown in FIG. 2, and the difference from FIG. The timer 13 is provided so that the variable capacity compressor 2 can be operated at maximum capacity a certain period of time before the start of the defrosting operation, and as a result, the timer 13 at the start of the defrosting operation It is possible to prevent drafts from occurring and avoid discomfort.

[Effects of the invention] In summary, this invention provides the following excellent effects.

1 When the variable capacity compressor side saves capacity and performs heating operation, when the constant capacity compressor side enters defrosting operation, the variable capacity compressor side starts heating operation at maximum capacity. As a result, the hot air blown out from the indoor unit does not drop below the room temperature that is sucked into the indoor unit, making it possible to maintain the room temperature and effectively preventing the blowing of cold air from the indoor unit. I can do it.

2. Compared to conventional systems that stop the indoor fan motor during defrosting operation, the defrosting time can be shortened as much as possible without stopping the indoor fan motor even during defrosting operation. Increased efficiency.

[Brief explanation of drawings]

Fig. 1 is a refrigeration cycle configuration diagram of a variable capacity air conditioner according to this invention, Fig. 2 is a block diagram showing an embodiment of the same defrosting control device, Fig. 3 is a timing chart of the same block, and Fig. 4 is a block diagram showing an embodiment of the same defrosting control device. The figure is a blowout temperature characteristic diagram, and FIG. 5 is a block diagram showing a modification of the defrosting control device. In the figure, 1 is a compressor with constant capacity, 2 is a compressor with variable capacity, 3 is an indoor heat exchanger, 6a, 6b are outdoor heat exchangers, 8a, 8b are sensors that detect direct frost, 9 is a control 11 and 12 are a frost formation judgment circuit and a comparison circuit that constitute the operation command means;
13 is a timer, A is a refrigeration cycle on the compressor side with constant capacity, B is a refrigeration cycle on the compressor side with variable capacity, C is an indoor unit, f is a defrosting operation command, i
is the capacity operation command, and h is the maximum capacity operation command.

Claims (1)

[Scope of utility model registration request] Two independent refrigeration cycles consisting of a compressor, four-way valve, outdoor heat exchanger, decompression device, and indoor heat exchanger are installed in one unit, and both indoor heat exchangers are combined to provide one refrigeration cycle with a constant capacity. Detect frost formation on the outdoor heat exchanger during heating operation in a variable capacity air conditioner that uses one compressor and a variable capacity compressor in the other refrigeration cycle, and both refrigeration cycles are operated by a control system. When the sensor detects frost on the refrigeration cycle side that has a compressor with constant capacity, it issues a defrost operation command to switch the four-way valve of that cycle to the defrost cycle and maintains the operation of the indoor fan motor. A defrosting control device for an air conditioner, characterized in that the control system is equipped with: and an operation command means for giving a maximum capacity operation command to a variable capacity compressor.