JP4295530B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner including an accumulator disposed on a suction side of a compressor.
[0002]
[Prior art]
The accumulator provided in the refrigeration cycle includes a tank, a gas refrigerant that is connected to the upper part of the tank and guides the evaporative refrigerant into the tank, and has a substantially U-shaped bent portion that is gas-liquid separated from the opening end of the upper part of the tank. And an oil return hole for returning the refrigeration oil collected at the bottom of the tank to the compressor.
[0003]
As a prior art, in [Patent Publication 1], in addition to the oil return hole at the bottom of the outlet pipe, at least one auxiliary oil return hole is provided along the vertical direction on the opening-side pipe wall of the outlet pipe so that liquid refrigerant is present. Regardless of the above, there is disclosed a technique capable of returning oil to the compressor through the auxiliary oil return hole even when the refrigeration oil and the liquid refrigerant are separated into two layers.
[0004]
[Patent Publication 1]
Japanese Patent Laid-Open No. 11-14201
[0005]
[Problems to be solved by the invention]
However, if the heating operation is performed when the outside air temperature is extremely low, a large amount of liquid refrigerant is temporarily stored in the accumulator at the time of startup. Under such conditions, the liquid refrigerant is sucked not only from the oil return holes but also from the plurality of auxiliary oil return holes, and the amount of liquid back to the compressor increases, which is not preferable in terms of the reliability of the compressor.
[0006]
In addition, the rotary compressor is particularly dangerous because the refrigerant is directly sucked into the compression chamber. The suction cup provided in the compressor suction section has a fixed oil return amount (hole diameter), so liquid refrigerant and oil tend to accumulate excessively in the suction cup, and there is a risk of damage to the compressor due to liquid compression and oil compression. There is.
[0007]
Further, in an air conditioner using a refrigerant having a relatively high operating pressure such as R32 or R410A, it is necessary to increase the tank thickness of the accumulator in terms of pressure resistance design. If the tank thickness is simply increased, the cost is increased. Therefore, it is common to increase the height dimension by reducing the tank diameter and increase the capacity.
[0008]
Even in such an accumulator, the oil return hole is provided at the lowermost part of the inlet pipe bending portion, so that when the two-layer separation of the refrigerator oil and the liquid refrigerant occurs, the oil existing on the liquid surface of the liquid refrigerant is compressed. It will not be returned to the machine.
[0009]
When liquid refrigerant or oil is accumulated only at the bottom of the accumulator, the oil return characteristic is deteriorated due to the difference in the head of the tank. This tendency is particularly noticeable at low temperatures when the viscosity of the oil is high.
[0010]
In order to improve this type of problem, the idea is to increase the flow rate of the refrigerant flowing in the outlet pipe and increase the differential pressure between the outlet pipe and the outside of the outlet pipe via the oil return hole, thereby improving the oil return characteristics. On the other hand, there is a problem that the pressure loss in the outlet pipe increases and the coefficient of performance decreases.
[0011]
The present invention has been made paying attention to the above circumstances, and its purpose is to reliably mix liquid refrigerant and oil even in a state where two-layer separation of liquid refrigerant and refrigerator oil occurs in the accumulator. Thus, it is an object of the present invention to provide an air conditioner that can improve the efficiency of oil return to the compressor and thus improve the reliability.
[0012]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, an air conditioner of the present invention is provided on the suction side of a compressor constituting a refrigeration cycle, and introduces refrigerant after being evaporated in a heat exchanger to perform gas-liquid separation. And an accumulator that introduces and guides the separated gas refrigerant into the compressor and diverts a part of the hot gas discharged from the compressor. In a state of blowing from the bottom of the inside Hot gas bypass circuit to be introduced and this hot gas bypass circuit Open / close valve provided It comprises.
[0013]
By adopting means for solving such a problem, even when the two-layer separation of the liquid refrigerant and the oil occurs in the accumulator, the liquid refrigerant and the oil are reliably mixed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a configuration diagram of a refrigeration cycle of an air conditioner, and FIG. 2 is a cross-sectional view illustrating the structure of an accumulator used in the refrigeration cycle.
[0016]
One port of the four-way switching valve 2 is connected to the refrigerant pipe P connected to the discharge part of the compressor 1, and the outdoor heat exchanger 3 and the refrigerant pipe P connected to the other port of the four-way switching valve 2, An electronic automatic expansion valve 4 and an indoor heat exchanger 5 which are expansion devices are sequentially provided and connected to the other port of the four-way switching valve 2.
[0017]
The refrigerant pipe connected to the remaining port of the four-way switching valve 2 is inserted into the accumulator 6 as an introduction pipe Pa that is the primary side of the accumulator 6 described later. The secondary side of the accumulator 6 communicates with a suction cup 7 provided at the suction portion of the compressor 1 as a lead-out pipe Pb.
[0018]
Thus, the air conditioner is provided with the heat pump type refrigeration cycle circuit K, and the discharge side refrigerant pipe P of the compressor 1 and the accumulator 6 are communicated with each other by a hot gas bypass circuit G described later.
[0019]
The bypass pipe 11 constituting the hot gas bypass circuit G has one end connected to the compressor discharge side refrigerant pipe P and the other end connected to the bottom of the accumulator tank 10.
[0020]
An on-off valve 12 and a capillary tube 13 are connected in series in the middle of the bypass pipe 11. In particular, the on-off valve 12 includes an electromagnetic coil unit that is electrically connected to a control unit (control unit) 15, and is controlled to open and close based on a control signal from the control unit 15.
[0021]
The accumulator 6 includes a tank 10 having a sealed structure, an introduction pipe Pa that is inserted into the tank 10 from above and an open end is located at the top of the tank, and a tank 10 that is inserted from the top of the tank 10 into the inside. A bent portion b that is bent in a substantially U shape is provided, and the open end c is provided with an introduction pipe Pb located at the upper portion of the tank 10.
[0022]
The leading ends of the introduction pipe Pa and the lead-out pipe Pb are provided by selecting positions that do not face each other. Although the leading end opening of the introduction pipe Pa is closed by the closing plate 16, the refrigerant can be introduced and guided into the tank 10 through a hole 17 provided in the vicinity of the leading end.
[0023]
An oil return hole 18 is provided in the bent portion b of the outlet pipe Pb in the tank 10. The position of the oil return hole 18 is provided at the lowermost portion of the bending portion c so that the amount of oil accumulation is minimized in a normal operation state where liquid refrigerant does not accumulate.
[0024]
As described above, the bypass pipe 11 constituting the hot gas bypass circuit G is connected to the bottom of the tank 10 constituting the accumulator 6, and the on-off valve 12 and the capillary tube 13 are provided in the bypass pipe 11.
[0025]
In the air conditioner having the above-described configuration, when the cooling operation is selected, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 is guided as indicated by solid arrows in the figure. The refrigerant evaporates in the indoor heat exchanger 5 to absorb the heat of evaporation from the room air, and the room air is dehumidified and cooled to obtain a cooling action.
[0026]
When the heating operation is selected, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 is guided as indicated by a broken line arrow in the figure. The refrigerant is condensed in the indoor heat exchanger 5 to release condensed heat to the indoor air, and the temperature of the indoor air is increased to obtain a heating action.
[0027]
In both the cooling operation and the heating operation, the evaporated refrigerant is introduced into the accumulator tank 10 through the introduction pipe Pa, and a gas-liquid separation action is performed. The separated gas refrigerant is sucked into the compressor 1 from the outlet pipe Pb. The separated liquid refrigerant accumulates at the bottom of the tank 10, evaporates and gasifies over time, and is sucked into the compressor 1.
[0028]
FIG. 3A schematically shows the state of the accumulator 6 when the heating operation is started under an extremely low temperature condition.
When the compressor 1 is started to perform the heating operation, a large amount of liquid refrigerant in the refrigeration cycle is temporarily accumulated in the accumulator 6. At this time, a large amount of oil is also released from the compressor 1 into the refrigeration cycle, and these oil also stays in the accumulator 6 together with the liquid refrigerant.
[0029]
That is, from the relationship of specific gravity, there is a liquid refrigerant layer R on the lower side of the tank 10 constituting the accumulator 6, and there is a refrigerating machine oil layer L above the liquid refrigerant layer R, so-called two-layer separation state. It has become.
[0030]
In such a case, liquid refrigerant or refrigeration oil is sucked from the oil return hole 18 in accordance with the flow differential pressure. However, particularly at low temperatures, the head difference due to the height of the accumulator tank 10 and the viscosity of the refrigeration oil increase. Return characteristics deteriorate.
[0031]
FIG. 3B is a diagram schematically showing a state in the accumulator 6 when the on-off valve 12 provided in the hot gas bypass circuit G is opened under the above-described conditions.
[0032]
By opening the on-off valve 12 of the hot gas bypass circuit G connected to the discharge side of the compressor 1, part of the hot gas discharged from the compressor 1 is guided to the accumulator 6 through the bypass pipe 11.
[0033]
The hot gas guided to the bypass pipe 11 is injected from the bottom of the accumulator tank 10 in a blown-up state. The liquid refrigerant layer R and the refrigerating machine oil layer L formed in the tank 10 are efficiently stirred by the injected hot gas, quickly evaporated and gasified, and guided to the compressor 1 through the outlet pipe Pb.
[0034]
That is, by bypassing the hot gas into the accumulator tank 10, the liquid refrigerant in the tank 10 can be quickly discharged to improve the return characteristics, and the reliability of the compressor 1 can be maintained.
[0035]
FIG. 4 shows the oil / refrigerant concentration of the ester oil-based refrigerating machine oil and the liquid separation characteristics of the refrigerant / refrigerating machine oil. In the figure, “insoluble” means a state where the oil and the liquid refrigerant do not melt at all, and “compatible” means that the oil and the liquid refrigerant are almost completely melted to form a substantially transparent state. “Suspension” refers to a state in which the oil is dissolved to some extent in the refrigerant, but there are many portions that do not melt, and the temperature is high and the oil becomes bubbles and becomes cloudy.
[0036]
In a certain region, the refrigerating machine oil and the liquid refrigerant are separated into two layers in the accumulator 6, and the refrigerating machine oil is positioned above the liquid refrigerant. As it is, the refrigeration oil cannot be sucked unless all the liquid refrigerant is sucked. While the liquid refrigerant is being sucked, the refrigeration oil does not return to the compressor at all, and there is a risk that the oil in the compressor 1 is insufficient and damaged.
[0037]
Since the hot gas bypass circuit G is provided here, even if there is an excessive liquid back and the two-layer separation of the refrigerating machine oil and the liquid refrigerant occurs in the accumulator 6, the liquid refrigerant is not cooled due to the stirring effect of the hot gas. Evaporation action is promoted and oil return to the compressor 1 is improved.
[0038]
Further, since it is not necessary to provide a plurality of oil return holes as in the prior art [Patent Publication 1], the oil return amount is not increased with the liquid return amount to the compressor, and the reliability of the compressor is not lowered. .
[0039]
FIG. 5 (A) is a diagram showing a structure of an accumulator 6A according to another embodiment, and FIG. 5 (B) is a configuration diagram of a refrigeration cycle of an air conditioner including the accumulator 6A.
[0040]
Since the refrigerating cycle circuit K itself is not particularly changed, the same number is assigned and a new description is omitted. The bypass pipe 11 constituting the hot gas bypass circuit G is connected to the lower part of the side surface portion of the accumulator tank 10.
[0041]
The accumulator 6A includes a tank 10, an introduction pipe Pa, a lead-out pipe Pb having a bent portion b, and an oil return hole 18 opened in the bent portion b of the lead-out pipe Pb.
[0042]
The tank 10 connection position of the bypass pipe 11 and the position of the oil return hole 18 corresponding thereto will be described. The oil return hole 18 is provided at a position existing 180 degrees with respect to the tank 10 connection position of the bypass pipe 11.
[0043]
That is, as shown in the figure, if the bypass pipe 11 is connected to the lower part of the left side surface of the tank 10, the oil return hole 18 is formed on the right side of the bent part b bent in the left-right direction of the outlet pipe Pb. Opened.
[0044]
Further, as shown by a two-dot chain line in the figure, if the bypass pipe 11 is connected to the back side of the tank 10, the oil return hole 18 is opened to the front side of the bent portion b. In any case, the connection height position Ha of the bypass pipe 11 is selected to be higher than the inner height Hb of the bent portion b of the outlet pipe Pb.
[0045]
In such a configuration, when the on-off valve 12 of the hot gas bypass circuit G is opened and the hot gas is guided to the accumulator tank 10, the hot gas goes upward from the connection position of the bypass pipe 11 by buoyancy.
[0046]
Therefore, the hot gas discharged from the bypass pipe 11 is not directly sucked into the oil return hole 18 (short circuit), and the liquid refrigerant can be efficiently stirred to avoid the two-layer separation.
[0047]
In addition, when the refrigerant | coolant used for a refrigerating cycle is a high pressure refrigerant | coolant like R32 or R410A, a pressure | voltage resistant design must be carried out, As a result, the thickness of the tank 10 of the accumulator 6 will become large and cost will increase.
[0048]
In order to avoid this, it is easiest to increase the height by increasing the height by reducing the body diameter. However, if the height increases, the liquid return characteristics and the oil return characteristics are caused by the head difference in the tank 10. Gets worse.
[0049]
In order to improve this type of problem, the idea is to increase the flow rate of the refrigerant flowing in the outlet pipe and increase the differential pressure between the outlet pipe and the outside of the outlet pipe via the oil return hole, thereby improving the oil return characteristics. On the other hand, there is a problem that the pressure loss in the outlet pipe increases and the coefficient of performance decreases.
[0050]
Here, since the hot gas bypass circuit G is provided as described above, even if the height of the tank 10 is increased, the hot gas blows upward (that is, in the height direction), and the liquid refrigerant and the refrigerating machine oil are discharged. It can be stirred efficiently and can be expected regardless of tank height.
[0051]
Moreover, in the accumulator tank 10 having a height, the oil return characteristic deteriorates in the direction in which the head difference increases, but the oil return characteristic can be secured by the stirring action by hot gas injection and the oil viscosity reduction.
[0052]
FIG. 6 shows a flowchart of an embodiment of the control unit 15 that controls the on-off valve 12 provided in the hot gas bypass circuit G.
[0053]
After starting the compressor 1 in step S1, the outside air temperature To detected by the temperature sensor in step S2 is compared with the set outside air temperature To1 stored in the control unit 15 in advance. When To is higher than To1 (YES), the process proceeds to step S3, and the control unit 15 continues the off (closed) state of the on-off valve 12.
[0054]
To But To1 than When it is low (NO), it is determined that a large amount of liquid refrigerant is accumulated in the accumulator 6, the process proceeds to step S <b> 4, and the control unit 15 turns on the on-off valve 12. That is, the on-off valve 12 is opened, and the hot gas is bypassed to the accumulator 6 to obtain the above-described effects.
[0055]
In either step S3 or step S4, the process moves to step S5 to activate the timer and wait for the elapse of the predetermined time t1. After the elapse of t1, the process proceeds to step S6, where the temperature Td of the refrigerant pipe P connected to the discharge side of the compressor 1 is detected and compared with the set temperature Td1 of the refrigerant pipe P stored in the control unit 15 in advance.
[0056]
Td is Td1 taller than In the case (YES), it moves to step S7 and the control part 15 switches the on-off valve 12 to off. That is, it is determined that the discharge gas temperature of the compressor 1 becomes higher than the set value and the refrigerant temperature rises as a whole and it is not necessary to cause the accumulator 6 to bypass the hot gas, and the on-off valve 12 is closed.
[0057]
When Td is lower than Td1 (NO), the process proceeds to step S8, the temperature ΔTd of the discharge-side refrigerant pipe P of the compressor 1 per unit time is calculated, and the discharge side per unit time stored in the control unit 15 in advance. Comparison is made with the set temperature ΔTd1 of the refrigerant pipe P.
[0058]
When the temperature ΔTd of the discharge side refrigerant pipe P of the compressor 1 in the calculated unit time is higher than the set temperature ΔTd1 in the unit time stored in the control unit 15 in advance (YES), the process returns to step S7 to return to the control unit 15 continues the off state of the on-off valve 12.
[0059]
When the temperature ΔTd of the discharge side refrigerant pipe P of the compressor 1 in the calculated unit time is lower than the set temperature ΔTd1 of the refrigerant pipe P in the unit time stored in the control unit 15 in advance (NO), the process proceeds to step S9. Then, the control unit 15 switches the on-off valve 12 to on and opens it to bypass the hot gas to the accumulator 6.
[0060]
By performing such control, it is possible to reliably determine the state in which liquid refrigerant or refrigerating machine oil tends to stay in the accumulator 6, and effective use of the hot gas bypass can be achieved.
[0061]
FIG. 7A is a refrigeration cycle configuration diagram of an air conditioner including control means for a hot gas bypass circuit G according to still another embodiment, and FIG. 7B is an actual control flowchart. .
Since the refrigeration cycle circuit K and the hot gas bypass circuit G are exactly the same as those described above, the same reference numerals are given here and new descriptions are omitted.
[0062]
As one means of control, the first temperature sensor 21 is attached to the introduction pipe Pa that is the primary side of the accumulator 6, and the second temperature sensor 22 is attached to the outlet pipe Pb that is the secondary side. 21 and 22 are electrically connected to a control unit (not shown).
[0063]
When the compressor 1 is started in step U1, the first temperature sensor 21 detects the temperature of the primary side of the accumulator 6 and sends the signal to the control unit in step U2. The second temperature sensor 22 detects the temperature on the secondary side of the accumulator 6 and sends the signal to the control unit.
[0064]
The control unit compares the temperature difference (T1−T2) between the primary side temperature T1 and the secondary side temperature T2 with the set temperature difference value ΔTa stored in the control unit in advance. If the difference between T1 and T2 is equal to or greater than the set temperature difference value ΔTa (YES), it is determined that liquid refrigerant or frozen oil is staying in the accumulator 6, and the process proceeds to step U3 where the on-off valve 12 is turned on and opened. The hot gas is bypassed to the accumulator 6.
[0065]
When the difference between T1 and T2 is equal to or less than the set temperature difference value ΔTa (NO) in step U2, it is determined that the hot gas bypass is unnecessary in the accumulator 6, and the process proceeds to step U4 to open / close valve 12 Turn off and close.
[0066]
Even after the hot gas is bypassed to the accumulator 6 in step U3, the first temperature sensor 21 and the second temperature sensor 22 continue to detect the temperature and send the signal to the control unit.
[0067]
The control unit compares the temperature difference value ΔTb set separately in step U5. This set temperature difference value ΔTb is a value slightly larger than 0, and asks whether or not there is a certain temperature difference between T1 and T2.
[0068]
If the temperature difference between T1 and T2 is equal to or less than the set temperature difference value ΔTb (YES), it is determined that the liquid refrigerant or refrigerating machine oil in the accumulator 6 has been completely discharged, and only the refrigerant gas has been reached, and the process proceeds to step U6 to open / close the valve. 12 is turned off and closed.
[0069]
If the difference between T1 and T2 is greater than or equal to the set temperature difference value ΔTb in step 5 (NO), it is determined that much liquid refrigerant or oil remains in the accumulator 6, and the process proceeds to step U3 to open / close valve 6 Turn on and release.
[0070]
By providing such a control means, it can be prevented that hot gas is unnecessarily supplied and the coefficient of performance is thereby lowered. Then, the on-off valve 12 can be actuated promptly in response to a change in the state of the accumulator 6 to improve the return characteristics and prevent liquid back by stirring and evaporation.
[0071]
In addition to the control means described above, means (for example, pressure sensor 23) for detecting the degree of refrigerant superheat is provided in the introduction pipe Pa that is the primary side of the accumulator 6, and the degree of superheat reaches the target value on the primary side of the accumulator 6. When the difference is reached and the difference between T1 and T2 is equal to or greater than the set value ΔTa, the on-off valve 12 may be turned on and opened.
[0072]
In any case, the on-off valve 12 is opened only when the difference between the temperature on the primary side and the temperature on the secondary side of the accumulator 6 exceeds the set temperature difference value. The internal liquid pool state is detected, and the stirring action by the hot gas bypass is obtained only when the liquid refrigerant is held.
[0073]
FIG. 8 is a refrigeration cycle configuration diagram of an air-conditioning apparatus including a hot gas bypass circuit Ga having a different configuration. The refrigeration cycle circuit K itself is the same as that described above, and the same reference numerals are assigned and a new description is omitted.
[0074]
A bypass pipe 11 is branched from the discharge side refrigerant pipe P of the compressor 1. The bypass pipe 11 is provided with an on-off valve 12 and a first capillary tube 25, and is connected to the bottom of the accumulator tank 10.
[0075]
Furthermore, the on-off valve 12 and the first capillary tube 25 Another bypass pipe 11a is branched from the middle part of the bypass pipe 11 between the second pipe 11a and a second capillary tube 26 is provided in the bypass pipe 11a, and a lead-out pipe which is the secondary side of the accumulator 6 is provided. It is connected to the middle part of Pb.
[0076]
That is, the hot gas bypass circuit Ga shunts a part of the hot gas discharged from the compressor 1 and introduces it to the bottom of the accumulator 6, and a part of the hot gas discharged from the compressor. Thus, a circuit to be introduced to the secondary side of the accumulator 6 is juxtaposed.
[0077]
The on-off valve 12 is provided on the upstream side of each circuit, and capillary tubes (throttle devices) 25 and 26 are provided in each circuit. These capillary tubes 25 and 26 serve as refrigerant flow countermeasures and flow rate adjustments.
[0078]
In such a configuration, when liquid refrigerant or refrigerating machine oil stays in the accumulator 6, the on-off valve 12 is opened to bypass the hot gas to promote stirring and evaporation in the accumulator 6, and return characteristics and evaporation characteristics are improved. Improve.
[0079]
Further, even if the gas refrigerant returning to the compressor 1 is cooled via the outlet pipe Pb which is the secondary side of the accumulator 6, hot gas is led from the circuit including the second capillary tube 26 to heat the refrigerant. .
[0080]
That is, while maintaining the bypass effect to the accumulator 6, the hot gas is directly injected into the compressor 1 suction side, so that the low pressure that is noticeable at the start-up after low temperature start-up and defrosting (defrosting) operation and at the head pipe It has the effect of preventing abnormal drop.
[0081]
Along with the effect of countermeasures against liquid refrigerant evaporation and two-layer separation due to stirring action on the accumulator 6, the heating effect of the suction of the compressor 1 can be obtained at the same time. Reliability can be ensured by preventing cooling.
[0082]
FIG. 9 is a configuration diagram of a refrigeration cycle of a so-called multi-type air conditioner composed of a combination of a plurality of outdoor units M1, M2 and a plurality of indoor units (not shown).
[0083]
Each of the outdoor units M1, M2 includes a plurality of compressors 1, a single oil separator 30, a four-way switching valve 2, Outdoor heat exchanger 3, the liquid tank 31 and the accumulator 6 are accommodated.
[0084]
Further, the outdoor units M1 and M2 are communicated with each other by a balance circuit B. The balance circuit B directly communicates with the compressors 1 arranged in the outdoor units M1 and M2, and also includes a suction side of the compressor 1, an oil separator 30 and an accumulator. 6 A branch circuit communicating with the secondary side of the.
[0085]
The outdoor units M1 and M2 are provided with a bypass pipe 11 branched from the refrigerant pipe P between the oil separator 30 and the four-way switching valve 2 and connected to the accumulator 6. A hot gas bypass circuit G including a capillary tube 13 is provided.
[0086]
The outdoor units M1 and M2 communicate with a plurality of indoor units (not shown) via the gas main refrigerant pipe PG and the liquid main refrigerant pipe PL. Each indoor unit contains an indoor heat exchanger, and these constitute a multi-type refrigeration cycle.
[0087]
Depending on the operating conditions, at least one outdoor unit (for example, M1) of the plurality may continue to operate, and the remaining outdoor units (for example, M2) may stop operating.
[0088]
At this time, in the outdoor unit M2 on the stop side, the refrigerant is recovered from the gas main refrigerant pipe PG during cooling and through the balance circuit B as shown by the one-dot chain line arrow in the drawing during cooling.
[0089]
However, when the stopped outdoor unit M2 is gas-balanced, a large amount of refrigerant stagnated in the low-pressure line stays in the liquid state, and particularly accumulates in the accumulator 6 in the stopped outdoor unit M2.
[0090]
When the outdoor unit M2 that has been stopped is activated again according to the operating conditions, the control unit controls to open the on-off valve 12 of the hot gas bypass circuit G. A part of the hot gas discharged from the compressor 1 is led to the accumulator 6 via the hot gas bypass circuit G, and the staying liquid refrigerant is quickly evaporated.
[0091]
In this manner, when the outdoor unit M2 that is stopped is present in a state where the outdoor unit M2 in which all of the compressors 1 that are mounted are present, the on-off valve 12 of the hot gas bypass circuit G is set to a predetermined value. By releasing the time and introducing the hot gas into the accumulator 6, the liquid compression after the activation can be avoided.
[0092]
【The invention's effect】
As described above, the present invention According to Even in the state where two-layer separation of liquid refrigerant and refrigeration oil occurs in the accumulator, the liquid refrigerant and oil are reliably mixed to improve the oil return efficiency to the compressor, thus improving the reliability. Play.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a refrigeration cycle of an air conditioner according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the accumulator according to the embodiment.
FIG. 3 is a diagram for explaining different states inside the accumulator according to the embodiment;
FIG. 4 is a characteristic diagram in a mixed state of refrigerant and refrigerating machine oil in the accumulator according to the embodiment.
FIG. 5 is a cross-sectional view of an accumulator and a refrigeration cycle configuration diagram according to another embodiment.
FIG. 6 is a control flowchart for an on-off valve of a hot gas bypass circuit according to still another embodiment.
FIG. 7 is a configuration diagram of a refrigeration cycle and a control flowchart for an on-off valve of a hot gas bypass circuit according to still another embodiment.
FIG. 8 is a configuration diagram of a refrigeration cycle according to still another embodiment.
FIG. 9 is a configuration diagram of a refrigeration cycle on the outdoor unit side according to still another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Compressor, 6 ... Accumulator, G ... Hot gas bypass circuit, 12 ... On-off valve, 10 ... Tank, Pa ... Inlet pipe, b ... Curved part, Pb ... Outlet pipe, 18 ... Oil return hole, 15 ... Control Part (control means).

Claims (6)

An air conditioner provided with an accumulator which is provided on the suction side of the compressor constituting the refrigeration cycle, introduces the refrigerant after evaporation in the heat exchanger and separates the gas and liquid, and introduces and guides the separated gas refrigerant to the compressor In the device
A hot gas bypass circuit for diverting a part of the hot gas discharged from the compressor and introducing the hot gas into the inside from the bottom of the accumulator;
An air conditioner comprising an on- off valve provided in the hot gas bypass circuit. An accumulator which is provided on the suction side of the compressor constituting the refrigeration cycle, introduces the refrigerant after being evaporated in the heat exchanger, gas-liquid separates, and introduces and guides the separated gas refrigerant to the compressor;
A hot gas bypass circuit for diverting a part of hot gas discharged from the compressor and introducing the hot gas into the accumulator;
The accumulator has a tank, an introduction pipe connected to the tank for introducing and guiding the evaporated refrigerant into the tank, and a bent portion that is bent in a substantially U shape near the bottom of the tank, and is open at the top of the tank. An outlet pipe that guides and guides the gas refrigerant separated from the open end to the compressor, and an oil return hole that guides the lubricating oil that is opened in the bent portion of the outlet pipe and that accumulates at the bottom of the tank to the compressor And
An air conditioner characterized in that the hot gas bypass circuit is connected to the accumulator tank at a position 180 degrees away from the oil return hole and higher than the inner height of the outlet pipe bending portion. Equipment .   The air conditioner according to any one of claims 1 and 2, wherein the refrigerant used in the refrigeration cycle is a high-pressure refrigerant such as R410 or R32.   The on-off valve provided in the hot gas bypass circuit is used when the outside air temperature is lower than the set temperature at the start of heating operation, or when the temperature change of the compressor discharge side refrigerant pipe after the start is lower than the set temperature change. The air conditioning apparatus according to any one of claims 1 to 3, further comprising control means for controlling the opening.   The on-off valve provided in the hot gas bypass circuit includes control means for controlling to open when the difference between the temperature on the primary side of the accumulator and the temperature on the secondary side exceeds a set temperature value. The air conditioning apparatus according to any one of claims 1 to 3.   The hot gas bypass circuit includes a circuit for diverting a part of the hot gas discharged from the compressor and introducing it to the bottom of the accumulator, and a part of the hot gas discharged from the compressor for diverting the accumulator. 6. A circuit to be introduced on a secondary side is provided in parallel, the on-off valve is provided on the upstream side of each circuit, and a throttle device is provided on each circuit. The air conditioning apparatus in any one of.

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