JPH0236063Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a heat pump dehumidifying dryer that uses a heat pump to dehumidify and dry objects to be dried stored in a drying chamber.

(Prior art) Fig. 2 shows a conventional heat pump dehumidifying dryer, in which 1 is a compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, 12 is an expansion valve for heating, and 4 is an expansion valve 12. Check valves connected in parallel, 6 a first indoor heat exchanger, 8 an expansion valve for dehumidification, 11 a check valve connected in parallel with the expansion valve 8, 9 a second indoor heat exchanger, 1
0 is an accumulator, which are connected by piping in the above order to constitute a refrigeration cycle of the heat pump.

In addition, 20 is an outdoor fan, 21 is an indoor fan,
22 is an outdoor unit cabinet, 23 is an indoor unit cabinet, and 24 is a drying cabinet.

In the dehumidifying dryer, an object to be dried is not put into the drying chamber 24, and heating operation is performed to raise the air inside the drying chamber and the object to be dried to a predetermined temperature. At this time, the refrigerant cycle shown in FIG. 2 operates as follows to perform heat pump heating.

In the outdoor heat exchanger 3, the refrigerant liquid is evaporated by the action of the outdoor fan 20 while absorbing heat from the drawn outside air as shown by the arrow, and enters the four-way switching valve 2 as a low-pressure refrigerant gas. Since the four-way switching valve 2 is connected between C and S, the low-pressure refrigerant gas leaving the outdoor heat exchanger 3 passes through the accumulator 10 and enters the compressor 1, where it is compressed into high-temperature, high-pressure gas. It becomes discharged refrigerant gas and enters the four-way switching valve 2. Since the four-way switching valve 2 is connected between DE and E, the high temperature and high pressure refrigerant gas enters the second indoor heat exchanger 9 in the indoor unit cabinet 23. The high-temperature refrigerant gas that has entered the second indoor heat exchanger 9 is partially condensed by the action of the indoor fan 21 while dissipating heat into the air inside the drying chamber sucked in as shown by the arrow, and passes through the check valve 11 to the second indoor heat exchanger 9. 1 enters the indoor heat exchanger 6. First indoor heat exchanger 6
The refrigerant gas and refrigerant liquid that have entered are completely condensed while dissipating heat to the air after exiting the second indoor heat exchanger 9,
It reaches the expansion valve 12 in the outdoor unit cabinet 22.
At this time, the check valve 4 is closed because the flow direction is reversed. The refrigerant that has been adiabatically expanded by the expansion valve 12 enters the outdoor heat exchanger 3 in a liquid/gas two-phase state, and the same action is repeated thereafter.

The thermal energy of the outside air absorbed by the outdoor heat exchanger 3 through the above refrigerant cycle is released by the indoor heat exchangers 6 and 6 by the action of the heat pump,
Perform heating operation.

When the air inside the drying chamber and the objects to be dried rise to a predetermined temperature by the above-mentioned heating operation, the dehumidifying operation is then started. The refrigerant cycle operates as follows to perform dehumidifying operation.

The refrigerant liquid flows into the indoor fan 2 in the second indoor heat exchanger 9.
1, the air inside the drying chamber sucked in as shown by the arrow is evaporated while being cooled and dehumidified, becomes low-pressure refrigerant gas, enters the accumulator 10 through the four-way switching valve 2 connected between E and S, and enters the compressor. It gets sucked into 1. The low-pressure refrigerant gas is compressed by the compressor 1 to become a high-temperature, high-pressure discharged refrigerant gas, which passes through the four-way switching valve 2 connected between D and C, passes through the outdoor heat exchanger 3, and the check valve 4, and then enters the first refrigerant gas. It enters the indoor heat exchanger 6. The high-temperature refrigerant gas that has entered the first indoor heat exchanger 6 condenses while dissipating heat into the cooled and dehumidified air in the second indoor heat exchanger 9 and reaches the expansion valve 8 . At this time,
The check valve 11 is closed because the flow direction is reversed. The air inside the drying chamber is heated by the heat of condensation of the refrigerant in the first indoor heat exchanger 6, and is blown out into the drying chamber as dry air. The refrigerant adiabatically expanded by the expansion valve 8 becomes a low-pressure liquid/gas two-phase state and is transferred to the second indoor heat exchanger 9.
, and the same action is repeated.

Through the above refrigerant cycle, the air inside the drying chamber is cooled and removed by the second indoor heat exchanger 9, then reheated by the first indoor heat exchanger 6, and blown out into the drying chamber as dry air. A dehumidifying operation is performed in which air is circulated around the object to be dried and the object is dried.

In addition, in order to maintain the temperature and humidity inside the drying chamber at a specified level,
The amount of heat released from the outdoor heat exchanger 3 is controlled by operating or stopping the outdoor fan 20.

The dehumidifying operation and heating operation described above need to be performed throughout the year, but if heating operation is performed in winter, frost may form on the fan of the outdoor heat exchanger 3 depending on the conditions. Therefore, when a predetermined condition is reached to remove this frost, it becomes necessary to perform a defrosting operation. The refrigerant cycle for defrost operation is the same cycle as for dehumidification operation, and the refrigerant flows from the compressor 1 to the four-way switching valve 2, to the outdoor heat exchanger 3, to the check valve 4, to the first indoor heat exchanger 6, to the expansion valve 8, to the second indoor The cycle returns to the compressor 1 via the heat exchanger 9, the four-way switching valve 2, and the accumulator 10. However, outdoor fan 20
is stopped, and the indoor fan 21 is operating. That is, the high-temperature refrigerant gas discharged from the compressor 1 is used to melt frost deposited on the fins of the outdoor heat exchanger 3.

(Problem to be solved by the invention) During the defrost operation, the refrigerant liquid condensed in the outdoor heat exchanger 3 passes through the check valve 4 and the first indoor heat exchanger 6 and reaches the expansion valve 8. In this case, the refrigerant liquid passes through the first indoor heat exchanger 6, which is not necessary (necessary for reheating the air inside the drying chamber that has been cooled and dehumidified by the evaporator during dehumidification operation). It accumulates inside the heat exchanger 6. Additionally, when the air temperature inside the drying chamber is high, the refrigerant liquid evaporates in the first indoor heat exchanger 6 and becomes refrigerant gas, which is supplied to the expansion valve, reducing the amount of refrigerant circulation and making it difficult for the frost to melt. . There was a problem that caused defrost failure.

(Means for solving the problems) The present invention includes a compressor, a four-way valve, an outdoor heat exchanger, a heating aperture, a first indoor heat exchanger, a dehumidifying aperture, a second
In the heat pump dehumidifying dryer in which indoor heat exchangers are connected in this order to constitute a heat pump cycle, and at the time of defrosting, refrigerant gas discharged from the compressor is introduced into the outdoor heat exchanger through a four-way valve for defrosting. First and second solenoid valves that are closed during defrosting are provided before and after the indoor heat exchanger,
A first bypass circuit having a third solenoid valve that opens during defrosting is connected to the first and second solenoid valves and the first indoor heat exchanger, and the second solenoid valve, the dehumidification aperture, and The second indoor heat exchanger is characterized in that a second bypass circuit having a fourth solenoid valve that is opened during defrosting is connected to the second indoor heat exchanger.

(Function) During defrosting, the refrigerant gas discharged from the compressor enters the outdoor heat exchanger via the four-way valve, condenses while dissipating heat onto the frost on the fins, and the frost begins to melt due to the heat. The condensed refrigerant liquid passes through the first bypass circuit, passes through a dehumidifying throttle, enters the second indoor heat exchanger, evaporates here, returns to the compressor via a four-way valve, and circulates through the outdoor heat exchanger. Defrost.
During this time, the refrigerant bypasses the first indoor heat exchanger,
Also, by switching to defrost operation, the first
The refrigerant trapped in the indoor heat exchanger flows out through the second bypass circuit to the outlet side of the second indoor heat exchanger connected to the suction side of the compressor, returns during the cooling cycle during defrost, and effectively acts on defrost. do.

(Example) Figure 1 shows an example of the present invention.
Regarding the conventional one shown in the figure,
The same reference numerals will be given and the explanation will be omitted.

In this embodiment, solenoid valves 5 and 7 that are closed during defrosting are provided on both sides of the first indoor heat exchanger 6.
A first bypass circuit 13 having a solenoid valve 14 that opens during defrosting is provided between the side of the solenoid valve 5 closer to the outdoor heat exchanger and the side of the solenoid valve 7 closer to the second heat exchanger. A second bypass circuit 15 having a solenoid valve 16 that opens during defrosting is provided between the exchanger 6 and the solenoid valve 7 and between the second indoor heat exchanger 9 on the four-way valve side.

Note that since the solenoid valves 5, 7, 14, and 16 all have flow in both directions, although reversible solenoid valves are shown in the illustration, it is also possible to use a one-way solenoid valve and a check valve in combination. In the heat pump dehumidifying dryer described above, the heating operation is the same as in the conventional example, with the outdoor heat exchanger 3 acting as an evaporator and the indoor heat exchangers 6 and 9 acting as condensers. At this time, the solenoid valves 5 and 7 are open, and the solenoid valves 14 and 16 are closed.

Also, the dehumidification operation is the same as in the conventional example, with the second indoor heat exchanger 9 being an evaporator, the first indoor heat exchanger 6 being a condenser,
The outdoor heat exchangers 3 are operated to control the amount of heat released and perform a dehumidifying operation. At this time, the solenoid valves 5 and 7 are open, and the solenoid valves 14 and 16 are closed.

On the other hand, during the defrost operation, the refrigerant cycle operates as follows to perform the defrost operation. Low-pressure refrigerant gas is compressed by compressor 1 and becomes high-temperature refrigerant gas.
It enters the outdoor heat exchanger 3 via the four-way switching valve 2. The high-temperature refrigerant gas that has entered the outdoor heat exchanger 3 condenses while dissipating heat onto the frost attached to the fins of the outdoor heat exchanger 3, and begins to melt due to the heat of the frost. The condensed refrigerant liquid passes through the check valve 4, passes through the bypass circuit 13 that bypasses the first indoor heat exchanger 6, and reaches the expansion valve 8. At this time, the solenoid valve 5 is closed and the solenoid valve 14 is open in order to allow the refrigerant to pass through the bypass circuit 13 that bypasses the first indoor heat exchanger 6.

Here, if the air temperature inside the drying chamber is low,
Bypass circuit 13 that bypasses indoor heat exchanger 6
Since the refrigerant liquid that has passed through will accumulate in the first indoor heat exchanger 6, the electromagnetic valve 7 is closed to prevent the refrigerant liquid from accumulating. Further, since the solenoid valves 5 and 7 are closed at the same time as the heating operation is switched to the defrost operation, the refrigerant that was flowing during the heating operation is trapped in the first indoor heat exchanger 6.

In order to prevent this, a bypass circuit 15 is provided to bypass the first indoor heat exchanger 6 to the outlet side of the second indoor heat exchanger 9, which serves as an evaporator during defrost operation. The contained refrigerant is returned to the refrigerant circulation circuit. At this time, the solenoid valve 16 is open. The refrigerant expanded adiabatically in the expansion valve 8 becomes a low-pressure liquid/gas two-phase state and enters the second indoor heat exchanger 9, where it evaporates and becomes a low-pressure refrigerant gas, which causes four-way switching. It enters the accumulator 10 through the valve 2 and is sucked into the compressor 1, and the same action is repeated thereafter.

(Effects of the invention) As is clear from the above, a simple refrigerant circuit can prevent refrigerant from accumulating in the first indoor heat exchanger, eliminate defrost failures, and perform stable defrost operation.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing one embodiment of the present invention;
The figure is a configuration diagram of a conventional device. 1... Compressor, 2... Four-way valve, 3... Outdoor heat exchanger, 4, 11... Check valve, 5, 7, 14, 1
6... Solenoid valve, 6... First indoor heat exchanger, 8...
Dehumidification expansion valve, 9...Second indoor heat exchanger, 12...
...Heating expansion valve, 13...First bypass circuit, 1
5...Second bypass circuit.

Claims (1)

[Scope of utility model registration request] Compressor, four-way valve, outdoor heat exchanger, heating throttle,
A first indoor heat exchanger, a dehumidifying throttle, and a second indoor heat exchanger are connected in this order to form a heat pump cycle, and at the time of defrosting, the refrigerant gas discharged from the compressor is sent to the outdoor heat exchanger through a four-way valve. In a heat pump dehumidifying dryer that is introduced and defrosted, first and second solenoid valves that are closed during defrosting are provided before and after the first indoor heat exchanger, and the first and second solenoid valves and the first indoor heat A first bypass circuit having a third solenoid valve that is open during defrost is connected to the exchanger, and the second solenoid valve, the dehumidification throttle, and the second indoor heat exchanger are opened during defrost. a second with a fourth solenoid valve;
A heat pump dehumidifying dryer characterized by being connected to a bypass circuit.