JPS63135748A - Refrigeration cycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a refrigeration cycle such as a heat pump type air conditioner.

(Prior technology) In the refrigeration cycle of a general heat pump type air conditioner, the amount of refrigerant charged is set to be the most efficient depending on the cooling, heating, indoor and outdoor air conditions, etc. No adjustments have been made. However, in a multi-system heat pump air conditioner in which indoor heat exchangers are connected in series via piping, the deterioration in efficiency cannot be ignored and some adjustment of the refrigerant sealing layer is required.

FIG. 5 shows a conventional refrigeration cycle of a two-chamber series piping multi-system, where 1 is a compressor and 2 is a four-way valve. This four-way valve 2 is connected to an expansion mechanism 7 via a first indoor heat exchanger 4 provided on the first v3 and a second indoor heat exchanger 6 provided on the second v5, and this expansion mechanism 7 is connected to the outdoor side. It is connected to the four-way valve 2 via a heat exchanger 8. The first indoor heat exchanger 4 includes a first indoor fan 4a.
However, the second indoor heat exchanger 6 has a second indoor fan 6a.
is provided.

Therefore, when heating two rooms, the first room 3 and the second room 5, the first indoor fan 4a and the second indoor fan 6a are turned on, and the refrigerant discharged from the compressor 1 is
The indoor heat exchanger 4 and the second indoor heat exchanger 6 exchange heat with indoor air to heat each room. The Mollier diagram of the cycle at this time is as shown by the solid line in Figure 6, and the distribution of liquid refrigerant and gas refrigerant in the first and second indoor heat exchangers 4.6 at this time. The state is schematically represented as shown in FIG. 7(A). That is, half of the discharged gas refrigerant is liquefied in the first indoor heat exchanger 4 (dryness 1/2) (point b of the sixth factor), and the remaining half of the gas refrigerant is liquefied in the second indoor heat exchanger 6. is liquefied and completely liquefied at the outlet of the second indoor heat exchanger 6 (point C in FIG. 6).

However, when heating the first chamber 5 and not heating the second chamber 5, the second indoor fan 6a is turned off, there is no heat exchange in the second chamber 5, and the refrigeration cycle is turned off as shown by the broken line in FIG. It exits the second indoor heat exchanger 6 in a gas-liquid mixed state without being completely liquefied in the first indoor heat exchanger 4. If the diameter of the valve serving as the expansion mechanism 7 is sufficiently large, the cycle will be stable in this state. The refrigerant distribution at this time is as shown in FIG. 7(B). In such operating conditions, the heating capacity of the first to third rooms is about the same as when heating two rooms, but the input is required to be the same as when operating two rooms simultaneously, and the efficiency of the refrigeration cycle is about half that of operating two rooms simultaneously. It will drop.

(Problems to be Solved by the Invention) As mentioned above, in a multi-system in which a plurality of indoor heat exchangers are connected in series, when only a part of the former stage is operated, the indoor heat exchanger of the latter stage is Since no heat exchange takes place in the refrigerant, the refrigerant is not completely liquefied and leaves the refrigerant in a mixed gas-liquid state, making it impossible to obtain the appropriate amount of refrigerant depending on the operating conditions, leading to a decrease in efficiency.

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a refrigeration cycle that can adjust the refrigerant m to an appropriate level under any operating conditions.

[Structure of the invention]

(Means and effects for solving the problem) This invention has the following features:
An electric expansion valve that can vary the amount of refrigerant depending on the opening is installed between the outdoor heat exchanger and the liquid tank, and the opening of this electric expansion valve is selected depending on the driving pattern to change the degree of dryness of the refrigerant in the liquid tank. By doing so, the volume of the liquid refrigerant and gas refrigerant in the liquid tank is changed to appropriately adjust the amount of refrigerant in the refrigeration cycle.

(Embodiment) Hereinafter, an embodiment of the present invention will be described based on FIG. 1, but the same components as the conventional one shown in FIG. 5 will be given the same reference numerals and the explanation will be omitted.

As shown in FIG. 1, a liquid tank 10 is provided between a second indoor heat exchanger 6 and an outdoor heat exchanger 8 provided in the second chamber 5. A first electric expansion valve 11 is provided at the rear, and a second electric expansion valve 12 is provided at the rear. An expansion valve controller 13 is connected to the drive units 11a and 12a of the first and second electric expansion valves 11.12.
By changing the opening degrees of the first and second electric expansion valves 11 and 12, the amount of refrigerant can be adjusted.

Next, the operation of the refrigeration cycle configured as described above will be explained. First, the expansion valve controller 13 sends a signal indicating that heating is necessary for both the first chamber 3 and the second chamber 5.
When received, the expansion valve controller 13 sets the opening degree of the first electric expansion valve 11 to a state close to fully open. Further, the opening degree of the second electric expansion valve 12 is controlled to keep the superheat of the suction gas of the compressor 1 constant, like a conventional expansion valve. In this way, since the opening degree of the first electric expansion valve 11 is large, the refrigerant liquefied at the outlet of the second indoor heat exchanger 6 will be transferred to the first electric expansion valve 11 even after passing through the first electric expansion valve 11. Since the pressure loss before and after the expansion valve 11 is small, the degree of dryness does not change much and an appropriate amount of liquid refrigerant accumulates in the liquid tank 10. This first and second indoor heat exchanger 4.6
The distribution state of the gas refrigerant and liquid refrigerant in the liquid tank 1o is shown in Fig. 3 (A), and the Mollier diagram of the cycle in this state is shown in Fig. 2 (A). Become. That is, the refrigerant state of the liquid tank 10 is d
The degree of dryness becomes small, and the liquid refrigerant in the liquid tank 10 increases.

Further, when the first air 3 is in the heating operation and the second air 5 is turned off, the expansion valve controller 13 receives this operating state.

Then, this expansion valve controller 13 sets the opening degree of the first electric expansion valve 11 to a narrowed state, and the second electric expansion valve 12 is controlled so that the superheat of the suction gas of the compressor 1 is constant. . At this time, since the opening degree of the first electric expansion valve 11 is small, the degree of dryness of the liquid tank 10 increases as shown at point d in FIG. 2(B), and the amount of gas refrigerant in the liquid tank 10 increases.

Therefore, the liquid refrigerant fills the second indoor heat exchanger 6 and is completely liquefied at the outlet of the first indoor heat exchanger 4. The refrigerant distribution state in this state is as shown in FIG. 3(B). Therefore, unlike the conventional case, the first indoor heat exchanger 4 does not completely liquefy and the efficiency decreases, and the normal efficiency can be maintained. However, although the capacity is for heating only one room, it produces a large amount of capacity, so the capacity of the compressor 1 needs to be controlled.

In the above embodiment, a refrigeration cycle in a multi-system in which a plurality of indoor heat exchangers are connected in series has been described, but as shown in FIG. Even in a refrigeration cycle in which evaporators 17 are connected in sequence, first and second electric expansion valves 1 are installed before and after the liquid tank 16.
8. By providing one, the amount of refrigerant can be adjusted.

In this case, the degree of subcooling is calculated by the expansion valve controller based on the pressure and humidity at the outlet of the condenser 15, and the opening degree of the first electric expansion valve 18 is adjusted so as to keep this degree of subcooling constant. When supercooling is small, the degree of opening of the first electric expansion valve 18 is reduced to increase the degree of dryness in the liquid tank 16, and the liquid refrigerant in the liquid tank 16 is stored on the condenser 15 side to increase the supercooling. . When the supercooling is large, the first electric expansion valve 18 is opened to reduce the degree of dryness in the liquid tank 16, and the liquid refrigerant in the condenser 15 is stored in the liquid tank 16. In this way, by adjusting the opening degree of the first electric expansion valve 18 so as to keep the degree of subcooling constant, the amount of refrigerant can be maintained at an appropriate level.

〔Effect of the invention〕

As explained above, according to the present invention, an electric expansion valve whose opening degree can be freely varied is provided at the front and rear of the liquid tank, so that the volume of the liquid refrigerant and gas refrigerant in the liquid tank can be adjusted by adjusting the opening degree. It is possible to appropriately adjust the amount of refrigerant in the refrigeration cycle by changing the amount of refrigerant, which has the effect of enabling highly efficient operation.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of this invention.
Figure 1 is a configuration diagram of the refrigeration cycle, second factors (A) and (B) are Mollier diagrams of the refrigeration cycle, and Figure 3 (A>(B) is a schematic diagram of the distribution of gas refrigerant and liquid refrigerant during operation. An explanatory diagram shown in
Fig. 4 is a block diagram of a refrigeration cycle showing another embodiment of the present invention, Fig. 5 is a block diagram of a conventional refrigeration cycle, Fig. 6 is a Mollier diagram of the refrigeration cycle, and Figs. ) is an explanatory diagram schematically showing the distribution of gas refrigerant and liquid refrigerant during operation. 1...Compressor, 4.6...Indoor heat exchanger,
8...Outdoor heat exchanger, 10...Liquid tank,
11.12...Electric expansion valve. Applicant's agent Patent attorney Takehiko Suzue (A)
(B) Figure 2 ON ON 1 to 3 Figure 4rlA Figure 5 6rIAM7r! ! J

Claims (3)

[Claims] (1) In a refrigeration cycle configured by sequentially connecting a compressor, an outdoor heat exchanger, a liquid tank, an expansion mechanism, and an indoor heat exchanger, an electric expansion valve that can vary the amount of refrigerant by changing the opening degree before and after the liquid tank A refrigeration cycle characterized by being provided with. (2) The refrigeration cycle according to claim 1, wherein the opening degree of the electric expansion valve is controlled by the operating pattern of the refrigeration cycle. (3) The refrigeration cycle according to claim 1, wherein the opening degree of the electric expansion valve is controlled so that the degree of subcooling at the outlet of the outdoor heat exchanger is constant.