JPS6234204Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a heat pump air conditioner that combines one outdoor unit and multiple indoor units. Fig. 1 shows the refrigerant system of a conventional heat pump air conditioner of this kind, in which 1 is a compressor;
2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is a first check valve, 5 is a second check valve, 6 is a third check valve, 7 is a liquid receiver, 8 is an expansion valve, and 9 is a third check valve. 4 check valve, 10, 11,
12 are first, second and third solenoid valves, 13 and 1, respectively;
4 and 15 are first, second and third indoor heat exchangers, respectively;
16, 17, and 18 are fourth, fifth, and sixth electromagnetic valves, respectively, and 19 is a temperature-sensitive tube of the expansion valve 8. A surrounded by a dashed line indicates an outdoor unit, and B, C, and D indicate an indoor unit. When operating three indoor units for cooling, compressor 1
As shown by the solid line arrow, the high-pressure and high-temperature refrigerant gas discharged from the The liquid passes through the check valve 4 and enters the receiver 7, undergoes adiabatic expansion in the expansion valve 8, becomes a low-pressure and low-temperature liquid, passes through the fourth check valve 9, and passes through the solenoid valves 10, 11, and 12, respectively, and undergoes indoor heat exchange. It enters the compressor 1 through the solenoid valves 16, 17, 18, and the four-way valve 2. be sucked into. During heating operation, the flow of refrigerant is opposite to that during cooling, and the refrigerant flows from compressor 1 to four-way valve 2 to solenoid valves 16, 17, and 18 to indoor heat exchanger 1, as shown by the dashed-dotted arrow.
3, 14, 15 → Solenoid valve 10, 11, 12 → 2nd
Check valve 5 → Liquid receiver 7 → Expansion valve 8 → Third check valve 6 →
The flow is from the outdoor heat exchanger 3 to the four-way valve 2 to the compressor 1.
When operating only indoor unit B, use solenoid valves 10 and 18.
is open, and solenoid valves 16, 17, 11 and 12 are closed. However, this type of heat pump air conditioner

[Table] In conventional air conditioners of this type, the circulation amount of refrigerant is controlled by the expansion valve 8, but with a normal expansion valve, the flow rate control range is 40 to 120 degrees based on the rated flow rate.
%, it is not possible to control the amount of circulation so as to satisfy all the required circulation amounts in various operating modes. In other words, if you choose an expansion valve with a capacity that matches the maximum circulation rate during cooling (45 to 130 kg/h), when one indoor unit is operated during warm-up, the flow rate to the expansion valve will be too large, causing the so-called hunting phenomenon. cause. In other words, when a large amount of refrigerant flows through the expansion valve 8, the entire amount of refrigerant cannot be evaporated in the outdoor heat exchanger 3, and is returned to the compressor 1 as a liquid. The temperature sensing cylinder 19 issues a signal to reduce the flow rate of refrigerant passing through the expansion valve 8 in order to prevent the refrigerant from returning to the compressor 1 as a liquid. becomes 0Kg/h. When the flow rate becomes 0, the temperature sensing cylinder 19 senses that the refrigerant is not flowing and sends a signal to the expansion valve 8 to cause the refrigerant to flow, so the refrigerant flow rate of the expansion valve 8 becomes 45 kg/h. In this way, although the refrigeration cycle requires a refrigerant flow rate of about 30 kg/h, the expansion valve 8 is 0.
The flow rate of Kg/h and 45Kg/h will be alternately flowed. This is the so-called expansion valve hunting phenomenon. When the hunting phenomenon occurs, the heating capacity decreases, and temporarily excessive refrigerant liquid returns to the compressor 1, causing liquid compression and damage to the compressor 1. Also, the durability life of the expansion valve is shortened. Problems such as shortening may occur. Conversely, if the capacity of the expansion valve is selected according to the minimum circulation amount during heating, the expansion valve will not be able to flow the maximum circulation amount during cooling. In other words, the refrigeration cycle requires a refrigerant flow rate of 125 kg/h, but the expansion valve 8 requires a flow rate of 80 kg/h.
This means that it can only flow. In view of the above, the present invention satisfies all the necessary refrigerant circulation amount of the refrigeration cycle by installing a first capillary tube in parallel with the expansion valve and installing a second capillary tube in series with the expansion valve. This is what I did. Hereinafter, one embodiment of the present invention shown in FIG. 2 will be described. In FIG. 2, the same members as those shown in FIG. 1 are given the same reference numerals, but the difference from FIG. , a second capillary tube 21 is installed in series with the expansion valve 8. When operating three indoor units for cooling, the refrigerant is distributed as shown by the solid arrows: compressor 1 → four-way valve 2 → outdoor heat exchanger 3 → first check valve 4 → liquid receiver 7 → expansion valve 8
→Fourth check valve 9 and first capillary tube 2
0 → Solenoid valve 10, 11, 12 → Indoor heat exchanger 1
Flows in the order of 3, 14, 15 → solenoid valves 16, 17, 18 → four-way valve 2 → compressor 1. The second check valve 5 and the third check valve 6 prevent the refrigerant from flowing to other paths. Since the first capillary tube 20 is installed in parallel with the expansion valve 8, the refrigerant circulation amount is the sum of (flow rate passing through the expansion valve 8) + (flow rate passing through the first capillary tube 20). As a result, both the upper and lower limits of the flow rate control width of the expansion valve 8 are raised. When operating three indoor units for heating, the refrigerant is transferred from compressor 1 to four-way valve 2 as shown by the dashed-dotted arrow.
Solenoid valves 16, 17, 18 → indoor heat exchangers 13, 1
4, 15 → Solenoid valves 10, 11, 12 → Second check valve 5 → Liquid receiver 7 → Expansion valve 8 → Second capillary tube 21 → Third check valve 6 → Outdoor heat exchanger 3 → Four sides It flows in the order of valve 2 → compressor 1. The fourth check valve 9 and the first check valve 4 prevent the refrigerant from flowing to any route other than the above-mentioned path. Furthermore, since the pressure at the inlet and outlet of the first capillary tube 20 is high, the refrigerant does not flow therein. Since the second capillary tube 21 is installed in series with the expansion valve 8, its purpose is to reduce the flow rate passing through the expansion valve 8. In other words, the flow rate G passing through the expansion valve is expressed as G=αF√ _{1 1} . where α; flow coefficient F; opening area P ₁ ; pressure of inlet fluid V ₁ ; specific volume of inlet fluid Opening area F is determined by the lift of the valve. Furthermore, the lift of the valve is determined by the pressure difference between the inlet and outlet of the expansion valve. In this way, the flow rate G increases when the pressure difference between the outlet and the inlet of the valve is large, and decreases when the pressure difference is small. This second capillary tube 21 is connected to the expansion valve 8
By installing the expansion valve 8 in series with the outlet of the expansion valve 8, the outlet pressure of the expansion valve 8 increases, the pressure difference between the outlet and the inlet becomes smaller, and the flow rate G decreases. In other words, both the upper and lower limits of the flow rate control width of the expansion valve 8 are lowered. Here, for the required refrigerant circulation amount of a heat pump type air conditioner with a capacity of about 4500 Kcal/h in Table 1: 60 to 125 Kg/h (1 to 3 units) during cooling and 30 to 65 〃 ( 〃 to 〃) during heating. , if you choose an expansion valve with a flow rate range of about 40 to 105 kg/h, the first capillary tube 2
If the size of the refrigerant is set to flow approximately 20 kg/h, the flow rate will be 60 to 125 kg/h, which satisfies the required refrigerant circulation amount during cooling. On the other hand, if the size of the second capillary tube 21 is determined so that the flow rate of the expansion valve 8 falls to about 30 to 80 kg/h, the necessary refrigerant circulation amount during heating can be satisfied. In addition, the expansion valve 8
is used within its control range in both cold and warm conditions, so no hunting phenomenon occurs. As mentioned above, compared to the conventional refrigerant flow rate control mechanism using only an expansion valve, the present invention can reduce the difference in the required refrigerant circulation amount during cooling and heating by simply adding two capillary tubes. Since it has become possible to eliminate the difference when changing the number of units, the required amount of refrigerant can be circulated through the air conditioner at all times, regardless of the operating condition, and the cooling and heating capacity is significantly increased compared to before. Furthermore, since hunting of the expansion valve can be eliminated, all problems such as damage to the compressor due to liquid compression and shortened durability of the expansion valve can be alleviated.

[Brief explanation of the drawing]

Figure 1 is a refrigerant system diagram of a conventional air conditioner;
The figure is a refrigerant system diagram showing one embodiment of the present invention. 1... Compressor, 3... Outdoor heat exchanger, 8... Expansion valve, A... Outdoor unit, 13, 14, 15... Indoor heat exchanger, B, C, D... Indoor unit, 20... …First
Capillary tube, 21...Second capillary tube.

Claims (1)

[Scope of utility model registration request] It consists of one outdoor unit equipped with at least a compressor, an outdoor heat exchanger, and an expansion valve, and a plurality of indoor units equipped with at least an indoor heat exchanger, and in the refrigerant circuit before and after the expansion valve. First and fourth check valves that allow refrigerant to flow from the outdoor heat exchanger to the indoor unit via the expansion valve are provided between the outlet side of the fourth check valve and the outlet side of the first check valve. A circuit having a second check valve is provided between the inlet side of the fourth check valve and a circuit having a third check valve between the inlet side of the fourth check valve and the inlet side of the first check valve. The refrigerant from the heat exchanger flows through the first check valve, the expansion valve, and the fourth check valve to the indoor unit, and during heating, the refrigerant from the indoor unit flows from the circuit having the second check valve to the expansion valve and the fourth check valve. In a heat pump air conditioner in which the air flows to an outdoor heat exchanger through a circuit having three check valves, a circuit having a first cooling capillary tube is provided in parallel with the expansion valve and the fourth check valve. A heat pump type air conditioner characterized in that a second capillary tube for heating is provided in the circuit having the third check valve.