JPS6212218Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a heat pump type air conditioner that performs cooling operation, heating operation, and defrost operation with a cooling cycle, and in particular prevents liquid back-up when mutually switching between heating operation and defrost operation. and related to shortening the defrosting operation time.

As shown in Fig. 1, a conventional heat pump type air conditioner includes a compressor 1, a four-way switching valve 2, an indoor heat exchanger 3, a cooling expansion valve 8 with a check valve 6 connected in parallel, and a liquid receiver. 11. A heating expansion valve 7 with a check valve 5 connected in parallel, an outdoor heat exchanger 4, a four-way switching valve 2, and an accumulator 12 are connected in this order to form a reversible annular refrigerant circuit R. , the heating expansion valve 7 and the cooling expansion valve 8 are provided in the temperature-sensitive cylinder 9 provided in the piping that serves as the outlet of the outdoor heat exchanger 4 during heating operation, and the piping that serves as the outlet of the indoor heat exchanger 3 during cooling operation. The refrigerant flow rate is adjusted during heating operation, cooling operation, and defrosting operation.

During heating operation, the refrigerant discharged from the compressor 1 circulates as shown by solid arrows. At this time, the refrigerant condenses and radiates heat in the indoor heat exchanger 3, expands in the heating expansion valve 7, and then passes through the outdoor heat exchanger 4.
It evaporates and absorbs heat, providing heating.

When the outdoor heat exchanger 4 reaches a predetermined frosting state, the four-way switching valve 2 is switched by the defrost thermometer 21 attached to the outdoor heat exchanger 4 to shift to defrost operation, but at this time, Compressor 1
The refrigerant discharged from the refrigerant circulates as shown by the broken line arrow. At this time, the refrigerant condenses and radiates heat in the outdoor heat exchanger 4 to melt and remove frost.

In the refrigerant circuit shown in FIG. 1, during heating operation, the temperature sensing cylinder 10 of the cooling expansion valve 8 is in a high temperature state due to the high temperature refrigerant gas discharged from the compressor 1. When switching to operation, the downstream side of the cooling expansion valve 8 becomes low pressure, the cooling expansion valve 8 instantaneously becomes fully open, and the liquid refrigerant in the liquid receiver 11 and the indoor heat exchanger 3 flows into the compressor 1. flows into.

Thereafter, the cooling expansion valve 8 returns to its normal function as the temperature sensing tube 10 is cooled, but the high pressure drops extremely during the defrost operation, so the cooling expansion valve 8 is kept at a predetermined opening degree (superheat degree 5 ℃ control), the refrigerant circulation amount decreases, and the defrost operation time becomes longer, and the defrost operation is performed with a large amount of liquid refrigerant stored in the outdoor heat exchanger 4. After the operation ends, the heating operation will have to be restarted.

Also, at that time, the temperature-sensitive tube 9 of the heating expansion valve 7 is at a high temperature due to the gas discharged from the compressor 1 during the defrost operation, and when the heating operation is resumed, the pressure on the downstream side of the heating expansion valve 7 becomes low, and the temperature rises instantaneously. As a result, the heating expansion valve 7 is fully opened, and a large amount of liquid refrigerant from the liquid receiver 11 and the outdoor heat exchanger 4 flows into the compressor 1, thus causing a liquid back-up when switching between heating operation and defrost operation. In addition, there is a problem that the defrosting operation time becomes longer.

The present invention has been made to improve the above-mentioned problems, and provides a heat pump type air conditioner that prevents liquid backflow when switching between heating and defrost operations, and shortens defrost operation time. The purpose is to

That is, the present invention includes a compressor 1, a four-way switching valve 2, an indoor heat exchanger 3, a cooling expansion valve that adjusts the refrigerant flow rate during cooling operation and defrost operation, and a cooling expansion valve that adjusts the refrigerant flow rate during heating operation. A heat pump that has a reversible annular refrigerant circuit R consisting of a heating expansion valve and an outdoor heat exchanger 4, and performs cooling operation, heating operation, and defrost operation by cooling cycle by switching operation of the four-way switching valve 2. In the air conditioner, an electric proportional control valve controlled by an electric signal from an expansion valve control circuit 20 is used as the cooling expansion valve and the heating expansion valve, and the expansion valve control circuit 20 includes a defrost control valve. During a preset predetermined time immediately after switching from heating operation to heating operation, the heating expansion valve is fully charged, and during a preset predetermined time immediately after heating operation is switched to defrost operation, the cooling expansion valve is fully charged. fully closing means for outputting a close electrical signal; adjusting means for outputting an electrical signal of an opening degree corresponding to the load to the heating expansion valve during heating operation after the predetermined time has elapsed; The air conditioner is characterized by further comprising fully opening means for outputting a fully open electric signal to the cooling expansion valve during the defrosting operation.

Hereinafter, based on the first embodiment shown in FIGS. 2 and 3 and the second embodiment shown in FIGS. 4 and 5,
The heat pump type air conditioner of the present invention will be explained.

First, a first example will be described. Compressor 1, four-way switching valve 2, indoor heat exchanger 3, check valve 6
A cooling expansion valve 8 with a check valve 5 connected in parallel, a heating expansion valve 7 with a check valve 5 connected in parallel, an outdoor heat exchanger 4, a four-way switching valve 2, and an accumulator 12 are connected in this order to create a reversible type. An annular refrigerant circuit R is formed, and the heating expansion valve 7 and the cooling expansion valve 8 are electric proportional control valves controlled by electric signals from a separately provided expansion valve control circuit 20. 7 adjusts the refrigerant flow rate during heating operation, and the cooling expansion valve 8 adjusts the refrigerant flow rate during cooling operation and defrost operation.

Further, reference numeral 21 indicates a defrost thermostat for detecting the frosting state on the outdoor heat exchanger 4 and transmitting it to the expansion valve control circuit 20 as an electric signal. Defrost thermostat 21 terminals a, a,
Terminal b of the heating expansion valve 7 and the cooling expansion valve 8,
b, c, c, and terminals d, d of the four-way switching valve 2
Terminals e and e of the heating thermostat 18 provided near the indoor heat exchanger 3 are connected to the expansion valve control circuit 20, respectively.
terminals a, a, b, b, c, c, d, d and e,
connected to e.

The switching operation of the four-way switching valve 2 performs a cooling operation, a heating operation, and a defrost operation using a cooling cycle in which refrigerant circulates in the same manner as the cooling operation. It is provided with means for controlling the heating expansion valve 7 and the cooling expansion valve 8 during operation as indicated by broken lines X and Y shown in FIGS. 3a and 3b.

That is, the expansion valve control circuit 20 is configured to control the heating expansion valve 7 for a predetermined period of time immediately after switching from the defrost operation to the heating operation, and to control the heating expansion valve 7 at a predetermined time period immediately after switching from the heating operation to the defrost operation. In time, cooling expansion valve 8
fully closing means for outputting a fully closed electric signal to each of the above, and adjusting means for outputting an electric signal of an opening degree corresponding to the load to the heating expansion valve 7 during heating operation after the predetermined time has elapsed; During the defrost operation after a period of time has elapsed, the system is equipped with a fully open means for outputting a fully open electric signal to the cooling expansion valve 8, and as shown in FIGS. At an arbitrary time T ₀ during the heating operation after a preset predetermined time has elapsed immediately after switching, the cooling expansion valve 8 is fully closed by the fully closing means in this embodiment, and the heating expansion valve 7 is, for example, in the heating mode. The valve is opened at an appropriate opening degree by the adjusting means to correspond to the heating load detected by the thermostat 18. During heating operation, when the defrost thermometer 21 issues a command to shift to defrost operation (time T ₁ ), the four-way selector valve 2 switches to the defrost operation side, and at the same time, the heating expansion valve 7 switches to the defrost operation side. In the embodiment, the device is fully closed by the fully closing means. Then, during a preset predetermined time t ₁ , the cooling expansion valve 8 continues to be fully closed by the fully closing means, and when the predetermined time t ₁ has elapsed (time T ₂ ), the cooling expansion valve 8 continues to be fully closed. It is fully opened by the fully opening means. Thereafter, when the defrost thermometer ₂₁ instructs the end of the defrost operation at time T3, the four-way selector valve 2 switches to the heating operation side, and at the same time, the cooling expansion valve 8 is fully closed in this embodiment. It becomes fully closed by means.

Even when switching to heating operation, the heating expansion valve 7 continues to be fully closed by the fully closing means during a preset predetermined time _t2 , and when the predetermined time _t2 has elapsed (time _T4 ), the heating expansion valve 7 continues to be fully closed. The expansion valve 7 is controlled to an appropriate opening degree by the adjusting means.

Therefore, in the above embodiment, the cooling expansion valve 8 is fully closed during the heating operation and the heating expansion valve 7 is fully closed during the defrosting operation by the fully closing means, but the check valve 6 is fully closed during the heating operation. During the cooling operation, the refrigerant flows through the check valve 5, so the cooling expansion valve 8 during the heating operation and the heating expansion valve 7 during the defrosting operation do not contribute to the regulation of the refrigerant, so they are completely closed. It doesn't have to be fully open or it can be at any opening.

Therefore, explanations of the cooling expansion valve 8 during heating operation and the heating expansion valve 7 during defrost operation, which do not contribute to refrigerant adjustment, will be omitted, and the heating expansion valve 7 and heating expansion valve 7 during heating operation, which contribute to refrigerant adjustment, will be omitted. When the cooling expansion valve 8 during the defrost operation is collectively expressed as an expansion mechanism E, the operation of the expansion mechanism E is as indicated by the broken line W in FIG. 3c.

That is, at an arbitrary time T ₀ during the heating operation after a preset predetermined time has elapsed immediately after switching from the defrost operation to the heating operation, the expansion mechanism E acting as a heating expansion valve is detected by the heating thermometer 18. The valve is opened at an appropriate opening degree by the adjusting means to correspond to the heating load. When time T ₁ is reached and the state is reached to shift to defrost operation, the four-way selector valve 2 switches to the defrost operation side, and at the same time, the expansion mechanism E, which acts as an expansion valve for cooling, is once fully closed by the fully closing means. It is said that Thereafter, when a preset predetermined time t ₁ has elapsed (time T ₂ ), the expansion mechanism E, which acts as an expansion valve for cooling, is fully opened by the full opening means, and remains in the fully open state until the defrost operation ends (time T ₃ ). maintained. When the defrost operation ends at time _T3 , the four-way switching valve 2 is switched to the heating operation side, and at the same time, the expansion mechanism E, which functions as a heating expansion valve, is fully closed by the fully closing means. The expansion mechanism E, which acts as a heating expansion valve, operates at time t ₂
After (time T ₄ ) the opening degree is controlled by the adjusting means to an appropriate degree corresponding to the heating load.

Next, a second embodiment shown in FIGS. 4 and 5 will be described. The difference between the second embodiment and the first embodiment is that a single cooling/heating expansion valve 17 is used as both the heating expansion valve 7 and the cooling expansion valve 8 in the first embodiment. The check valve 13,
16 and a check valve 14, 1 which is in the forward direction during heating operation.
5 is the four sides, and the cooling/heating expansion valve 17 is arranged in the middle in a so-called bridge circuit, and the terminals b, b of the cooling/heating expansion valve 17 are connected to the expansion valve control circuit 2.
Only the points connected to terminals b and b of 0 are connected. The heating and cooling expansion valve 17 functions as a cooling expansion valve that adjusts the refrigerant flow rate during cooling operation and defrost operation, and as a heating expansion valve that adjusts the refrigerant flow rate during heating operation. The operation of the cooling/heating expansion valve 17 and the four-way switching valve 2 is as follows.
The operations shown in FIGS. 5a and 5b are the same as those shown in FIGS. 3c and d, so the explanation will be omitted.

As is clear from the descriptions of the above embodiments, the present invention provides the following advantages:
Immediately after the heating expansion valve is switched from heating operation to defrost operation, each cooling expansion valve is fully closed during a preset predetermined time period. At the same time, liquid backflow to the compressor can be prevented. Furthermore, since an increase in the amount of liquid refrigerant returned to the compressor is avoided, the capacity of the accumulator can be made smaller than in the past.

Furthermore, according to the present invention, during defrost operation after a preset period of time has passed immediately after switching from heating operation to defrost operation, the cooling expansion valve is fully opened, ensuring a sufficient amount of refrigerant circulation. Thus, the time required for defrosting operation can be shortened. In addition, since an electric proportional control valve is used as the expansion valve, it can be opened and closed accurately based on the output from the expansion valve control circuit, and during normal heating operation, the opening degree can be adjusted to suit the load. It has many practical effects such as stable heating operation.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram in a conventional heat pump type air conditioner, Fig. 2 is a refrigerant circuit diagram in a heat pump type air conditioner according to an embodiment of the present invention, and Figs. FIG. 4 is a refrigerant circuit diagram in a heat pump air conditioner according to another embodiment of the present invention, and FIGS. 5 a and b are operation explanatory diagrams of the refrigerant circuit in FIG. be. 1...Compressor, 2...Four-way switching valve, 3...Indoor heat exchanger, 4...Outdoor heat exchanger, 7...Heating expansion valve, 8...Cooling expansion valve, 17... ...Air conditioning/heating expansion valve, 20...Expansion valve control circuit, R...Reversible annular refrigerant circuit.

Claims (1)

[Scope of utility model registration request] Compressor 1, four-way switching valve 2, indoor heat exchanger 3,
It has a reversible annular refrigerant circuit R consisting of a cooling expansion valve that adjusts the refrigerant flow rate during cooling operation and defrost operation, a heating expansion valve that adjusts the refrigerant flow rate during heating operation, and an outdoor heat exchanger 4, In a heat pump type air conditioner that performs a cooling operation, a heating operation, and a defrost operation through a cooling cycle by switching the four-way switching valve 2, an expansion valve control circuit 2 serves as the cooling expansion valve and the heating expansion valve.
Using an electric proportional control valve controlled by an electric signal from zero, the expansion valve control circuit 20 is configured to control the expansion valve for heating during a preset predetermined time period immediately after switching from defrost operation to heating operation. The valve includes fully closing means for outputting a fully closed electric signal to each of the cooling expansion valves during a preset predetermined time immediately after switching from heating operation to defrost operation, and during heating operation after the elapse of the predetermined time. an adjusting means for outputting an electric signal of an opening degree corresponding to the load to the heating expansion valve; and a fully opening means for outputting a fully open electric signal to the cooling expansion valve during defrost operation after the predetermined time has elapsed. A heat pump air conditioner characterized by comprising: