JPH10176875A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner having a plurality of compressors in which a damage of each of the compressors caused by liquid compression or lack of lubricant oil can be prevented. SOLUTION: There are provided an accumulator 2 to which a refrigerant feeding-in pipe 3 and refrigerant outflow pipes 4a, 4b are connected, and compressors 1a, 1b connected to the accumulator 2 through each of the refrigerant outflow pipes 4a, 4b, respectively. In an air conditioner in which refrigerant outflow ports 41a and 41b of the refrigerant outflow pipes 4a, 4b are arranged at higher position than that of a bottom part of the accumulator 2, there are provided a plurality of oil returning pipes 5a, 5b of which one end of each of the pipes is connected to the bottom part of the accumulator 2 and the other ends are connected to the refrigerant outflow pipes 4a, 4b at higher positions than that of the bottom section of the accumulator 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a plurality of compressors.

[0002]

2. Description of the Related Art A conventional air conditioner includes a laterally substantially cylindrical accumulator as disclosed in Japanese Patent Application Laid-Open No. 4-358778, and a plurality of refrigerant outlet pipes for communicating the accumulator with a compressor. There was something to prepare. In this air conditioner, the plurality of refrigerant outflow pipes are connected to the bottom of the accumulator at predetermined intervals in the longitudinal direction of the accumulator, and each of the refrigerant outflow pipes is extended upward from the connection position. The refrigerant outlet at the tip opens at a predetermined height in the accumulator. Also, an oil return hole located near the bottom in the accumulator was formed in each refrigerant outflow pipe. Further, a partition plate for dividing the inside of the accumulator into an inflow chamber and an outflow chamber is provided, and a communication hole is formed in the partition plate.

[0003]

In the prior art, when the air conditioner is provided with a horizontal multi-cylinder compressor, the connection position of each refrigerant outlet pipe to the accumulator is changed to the horizontal multi-cylinder compressor. The connection position of each of the refrigerant outflow pipes can be determined as a reference, and the effect that the air conditioner can be formed more compactly is exhibited. However, when the air conditioner includes a plurality of independent compressors, the shapes of the plurality of compressors are not necessarily the same, and the distance of each compressor from the accumulator is not necessarily the same. Furthermore, since each compressor is often not positioned in the same direction with respect to the accumulator, arranging a plurality of refrigerant outflow pipes in the longitudinal direction of the horizontally long accumulator may reduce the degree of freedom in piping design. there were.

[0004] In particular, in order to return a sufficient amount of lubricating oil to the compressor through the oil return holes formed in each refrigerant outflow pipe, it is necessary to open an oil return hole near the bottom of the accumulator.
For this reason, the refrigerant outflow pipe had to be connected to the bottom of the accumulator, so that a space was required below the accumulator to bend the refrigerant outflow pipe taken out of the accumulator in the direction of the compressor, and the accumulator itself. There is a possibility that the arrangement position of the air conditioner becomes high, and thus the overall height of the air conditioner becomes high.

Further, since the oil return hole is formed in the refrigerant outflow pipe so as to be located near the bottom of the accumulator,
When the liquid refrigerant accumulates in the accumulator while the compressor is stopped, the liquid refrigerant flows into the refrigerant outlet pipe from the oil return hole, and the refrigerant outlet pipe is also filled with the liquid refrigerant to the same level as the liquid level of the accumulator. is what happened. Therefore, when the compressor is started next time, the liquid refrigerant collected in the refrigerant outflow pipe is sucked into the compressor as it is to perform liquid compression,
The compressor could be damaged.

The lubricating oil flowing into the accumulator together with the refrigerant accumulates only in the inflow chamber and does not exit the outflow chamber until its liquid level reaches a communication hole formed in the partition plate. Lubricating oil is difficult to return from a certain oil return hole to the compressor, and the compressor may be damaged by depletion of the lubricating oil.

When a plurality of refrigerant outlet pipes each having a compressor connected to each end are connected to the accumulator in a state where they are arranged in the longitudinal direction of the horizontally long accumulator, the refrigerant outlet pipes are close to the refrigerant inlet into the accumulator. In a situation where the compressor connected to the refrigerant outlet pipe is stopped and the compressor connected to the refrigerant outlet pipe farther from the refrigerant inlet is operating, the compressor has flowed into the accumulator from the refrigerant inlet. The refrigerant flows to the refrigerant outlet of the refrigerant outlet pipe of the operating compressor while jumping over the refrigerant outlet of the refrigerant outlet pipe of the stopped compressor. For this reason, a part of the droplets of the liquid refrigerant enters the refrigerant outflow pipe of the stopped compressor, accumulates in the refrigerant outflow pipe, and the liquid back operation is performed when the stopped compressor is started. The compressor may be damaged by liquid compression.

Further, the inflow chamber and the outflow chamber are partitioned by a partition plate having a communication hole, but the communication hole is located on a straight line connecting the refrigerant inlet of the refrigerant inflow pipe and the refrigerant outlet of the refrigerant outflow pipe. In such a case, there is a high possibility that the liquid refrigerant from the refrigerant inlet directly flows to the refrigerant outlet, which may lead to a large amount of the liquid refrigerant returning to the compressor and leading to damage to the compressor due to liquid compression. .

The present invention has been made in order to solve the above problems, and is an air conditioner provided with a plurality of compressors. It is an object of the present invention to provide an air conditioner that can prevent damage. Another object of the present invention is to provide an air conditioner that can be downsized by increasing the degree of freedom in piping design in addition to the above objects.

[0010]

To achieve the above object, the present invention provides an accumulator to which a refrigerant inflow pipe and a plurality of refrigerant outflow pipes are connected, and a plurality of accumulators each connected to the accumulator through a refrigerant outflow pipe. In the air conditioner, comprising a compressor and the refrigerant outlet of the refrigerant outflow pipe is arranged at a position higher than the bottom of the accumulator, one end is connected to the bottom of the accumulator and the other end is at a position higher than the bottom of the accumulator. In this configuration, a plurality of oil return pipes connected to the plurality of refrigerant outlet pipes are provided.

[0011] In addition to the above-described structure, the apparatus further comprises control means for controlling the number of operating compressors, and stops when the control means performs control for operating only some of the compressors. The refrigerant outlet of the refrigerant outlet pipe connected to the machine is arranged at a position horizontally separated from the refrigerant inlet of the refrigerant outlet of the other refrigerant outlet pipes.

Further, in the above construction, the accumulator is formed in a substantially cylindrical shape in a horizontal direction, and the refrigerant outflow pipe is connected to a peripheral wall at a position displaced in a circumferential direction from the bottom of the accumulator.

Further, in addition to the above configuration, a partition plate for partitioning the inside of the accumulator into an inflow chamber having a refrigerant inlet and an outflow chamber having a refrigerant outlet is provided, and the partition plate has a refrigerant inlet, a refrigerant outlet, And a first communication hole communicating the inflow chamber and the outflow chamber at a position lower than the straight line connecting.

A partition plate formed with a second communication hole communicating the inflow chamber and the outflow chamber at a position shifted in a horizontal direction parallel to the partition plate from a straight line connecting the refrigerant inlet and the refrigerant outlet. It is.

A third communication hole is formed in the partition plate at a position higher than the bottom of the accumulator to communicate the inflow chamber and the outflow chamber, and one end of the oil return pipe is connected to the bottom of the inflow chamber. is there.

Further, a fourth communication hole for communicating the inflow chamber and the outflow chamber is formed in the partition plate, and a liquid level detecting means for detecting the liquid level in the accumulator is provided in the outflow chamber. is there.

Further, a fifth communication hole communicating the inflow chamber and the outflow chamber is formed in the partition plate, and refrigerant direction changing means for changing a flow direction of the refrigerant passing through the fifth communication hole is provided. .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 of the Invention FIG. 1 shows an accumulator and a compressor of an air conditioner according to Embodiment 1 of the present invention. In the figure, 1a and 1b are compressors, 2 is an accumulator formed in a laterally substantially cylindrical shape, and 3 is a refrigerant in a refrigerant circuit (not shown) including a heat source side heat exchanger and a use side heat exchanger. Refrigerant inflow pipes 4a and 4b for inflow into the accumulator 2 are refrigerant outflow pipes 5a and 5b for allowing refrigerant to flow out of the accumulator 2 and returning to the compressors 1a and 1b, respectively. An oil return pipe is connected and the other end is connected to the refrigerant outflow pipes 4a and 4b, respectively, and 6a and 6b are discharge pipes of the compressors 1a and 1b, respectively.

Also, h1 and h2 indicate the height difference between the positions where the oil return pipes 5a and 5b are connected to the refrigerant outflow pipes 4a and 4b, respectively, and the bottom of the accumulator 2. Thus, the oil return pipes 5a and 5b Each is connected to the refrigerant outflow pipes 4a and 4b at a position higher than the bottom of the accumulator 2. Further, h6 indicates a height difference between the refrigerant outlets 41a, 41b at the tips of the refrigerant outlet pipes 4a, 4b and the bottom of the accumulator 2. Further, the bold arrow in the drawing indicates the direction in which the gas refrigerant or the liquid mixture of the liquid refrigerant and the lubricating oil flows. In addition, as the oil return pipes 5a and 5b, the refrigerant outflow pipe 4
A tube with a smaller diameter than a and 4b is used.

FIG. 2 shows a cross section perpendicular to the cylinder center direction of the accumulator 2. As shown in FIG.
a and 4b are connected to the bottom of the accumulator 2 and extend vertically upward from this connection position to protrude into the accumulator 2. The oil return pipes 5a and 5b are also connected to the bottom of the accumulator 2.

With the above configuration, during operation of the compressors 1a and 1b, pressure is generated at one end and the other end of the oil return pipes 5a and 5b by pressure loss generated in the refrigerant outflow pipes 4a and 4b. Due to the difference, the lubricating oil accumulated at the bottom in the accumulator 2 passes through the oil return pipes 5a, 5b and the refrigerant outflow pipes 4a, 4b.
b and merged into the compressors 1a and 1b. Further, for example, even when only the compressor 1a is operated and the compressor 1b is stopped, and the mixed liquid of the liquid refrigerant and the lubricating oil is accumulated in the accumulator 2, the level of the liquid surface is high. Is less than h2, the liquid mixture in the accumulator 2 does not flow into the refrigerant outflow pipe 4b through the oil return pipe 5b. Therefore, the mixed liquid does not accumulate in the refrigerant outflow pipe 4b, so that the occurrence of liquid back when the compressor 1b is started next time can be prevented, and damage to the compressor 1b can be avoided.

As described above, since the predetermined heights h1 and h2 are secured as the merging heights with the outflow pipes 4a and 4b in both the oil return pipes 5a and 5b, only the compressor 1a is stopped. Even when the compressors 1a and 1b are both stopped, the outflow pipes 4a and 4
The trouble caused by the liquid back at the time of starting can be avoided without the mixed liquid staying in the b.

In general, when the compressors 1a and 1b are vertical and substantially cylindrical compressors, they are higher than horizontal and substantially cylindrical compressors. The connection position with the machines 1a and 1b also becomes higher. Therefore, in the air conditioner having the structure as shown in FIG. 1, it is possible to increase the height difference between h1 and h2 in FIG. 1, and even if the liquid level in the accumulator 2 becomes high, the height difference h1 corresponding thereto is increased. , H2 is secured, and the reliability of the air conditioner is further improved. In particular, the accumulator 2 has a substantially cylindrical compressor 1a,
If the length (that is, the height) of 1b in the cylinder core direction is long, there is a high possibility that the height difference between h1 and h2 can be made higher than a possible liquid level in the accumulator 2. From this, it can be said that when the vertical cylindrical compressor and the horizontal cylindrical accumulator are combined, the effect of preventing damage to the compressor is particularly large.

Embodiment 2 of the Invention FIG. 3 shows an accumulator according to Embodiment 2 of the present invention in a cross section perpendicular to the cylinder center direction. In this embodiment, the refrigerant outflow pipes 4a and 4b are provided at the bottom of the accumulator 2 having a substantially horizontal cylindrical shape. (Ie, the lowest position) is connected to the peripheral wall at a position shifted in the circumferential direction. However, the refrigerant outlets 41a, 4a at the tips of the refrigerant outlet pipes 4a, 4b in the accumulator 2 are provided.
The opening position of 1b is the same as that in FIG. 2 in the first embodiment of the invention. The oil return pipes 5a and 5b are connected to a position where the peripheral wall at the bottom of the accumulator 2 is lowest as in FIG.

As described above, the refrigerant outlet pipes 4a, 4b and the oil return pipes 5a, 5b are separately connected to the bottom of the accumulator 2, and the refrigerant outlet pipes 4a, 4b and the oil return pipes 5a, 5b are connected to the refrigerant more than the accumulator 2. With a configuration in which the refrigerant is merged on the downstream side in the flow direction, it is not always necessary to take out the refrigerant outflow pipes 4a and 4b from the bottom of the accumulator 2. Therefore, the refrigerant outlet pipes 4a, 4b are provided at the bottom of the accumulator 2.
If only the thinner oil return pipes 5a and 5b are connected, a space for bending the thick refrigerant outflow pipes 4a and 4b in the direction of the compressor is not required below the accumulator 2, and the installation position of the accumulator 2 is reduced. It is also possible to lower it. In addition, since the refrigerant outflow pipes 4a and 4b can be taken out at positions other than below, the degree of freedom in piping design is increased, and the size of the air conditioner can be reduced while lubricating oil accumulated at the bottom of the accumulator 2 is sufficiently returned.

Further, if necessary, the refrigerant outlet pipe 4a and the refrigerant outlet pipe 4b can be connected to different positions in the circumferential direction of the peripheral wall of the accumulator 2 as shown in FIG.

Embodiment 3 of the Invention FIG. 6 shows a refrigerant circuit of an air-conditioning apparatus according to Embodiment 3 of the present invention, where 1a, 1b,..., 5a, and 5b have the same configuration as that shown in FIG. Element. 7 is a four-way switching valve for switching between cooling operation and heating operation, 8 is a heat source side heat exchanger, 9a and 9b are flow control devices, 10a and 1
0b is a use side heat exchanger. And 11 is the compressor 1
A high pressure sensor detects the pressure of the refrigerant discharged from a or 1b, and a low pressure sensor 12 detects the pressure of the refrigerant at the inlet of the accumulator 2. In the drawing, the solid thick arrow indicates the flow of the refrigerant during cooling, and the broken thick arrow indicates the flow of the refrigerant during heating. In this case, the compressor 1a is a compressor whose capacity can be controlled, and the compressor 1b is a fixed capacity compressor that starts / stops as necessary. Also,
As shown in FIG. 5, the accumulator 2
The configuration of the part reaching to a and 1b is the same as that of FIG. 1, and the refrigerant inflow port 31 at the tip of the refrigerant inflow pipe 3 and the refrigerant outflow pipes 4a and 4b
The refrigerant outlets 41a and 41b at the leading end of b are arranged on a straight line along the cylinder center direction of the accumulator 2, and the refrigerant outlet 41b is farther away from the refrigerant inlet 31 than the refrigerant outlet 41a in the horizontal direction. It is arranged in a position.

FIG. 7 is a control block diagram for controlling the compressor, and includes a high pressure sensor 11 and a low pressure sensor 12.
The control device 13 changes the operating frequency of the compressor 1a via the inverter 14 based on a predetermined control flow, and controls the operation / stop of the compressor 1b via the switch 15 in response to the output of the control device 13.

FIG. 8 shows the compressors 1a,
It is the flowchart which showed the control content of 1b. First, in step S1, it is determined whether the current operation state is cooling or heating. Step S in case of cooling
In 2, it is determined whether or not the output value (Ps) of the low pressure sensor 12 is higher by a predetermined value s than a preset target value Psm. If Ps is higher than Psm + s, the change width ΔF of the operating frequency of the compressor 1a is set to + b (where b> 0) in step S3. P in step S2
If s is lower than Psm + s, the next step S4
Then, it is determined whether Ps is lower than Psm-s. If it is low, the change width ΔF of the frequency of the compressor 1a is set to −b in step S5. Ps is Psm in step S4
If higher than −s, ΔF = 0 is set in step S6.

On the other hand, if it is determined in step S1 that the operating state is heating, the output value (Pd) of the high pressure sensor 11 is increased by a predetermined value d from a preset target value Pdm in step S7. Determine if it is high. If Pd is higher than Pdm + d, the change width ΔF of the operating frequency of the compressor 1a is set to − in step S8.
a (where a> 0). Pd becomes Pd in step S7
If it is lower than m + d, it is determined in the next step S9 whether or not Pd is lower than Psm-d. If it is low, the change width ΔF of the operating frequency of the compressor 1a is set to + a in step S10. In step S9, Pd becomes Psm-d
If higher, ΔF = 0 is set in step S6.

In step S11, a value obtained by adding ΔF determined so far to the operating frequency F * of the compressor 1a currently operating is set as the operating frequency F. In S12, F
Is greater than or equal to a preset maximum value Fmax. If F ≧ Fmax, it is determined whether or not the compressor 1b is stopped in step S13. If stopped, the compressor 1b is started in step S14 and the frequency of the compressor 1a is reduced to a predetermined value Fa. . Step S
If it is determined in step 13 that the compressor 1b is already operating, the process returns to step S1 while keeping the current frequency control.

If F <Fmax in step S12, it is determined in step S15 whether F is equal to or less than a preset minimum value Fmin. If F ≦ Fmin, it is determined whether or not the compressor 1b is operating in step S17. If so, the compressor 1b is stopped in step S18 and the frequency of the compressor 1a is set to a predetermined value Fa.
Up to If F> Fmin is determined in step S15, F is output in step S16.

As described above, in the air conditioner of this embodiment, the compressor 1a is always operated, and the high frequency pressure and the low pressure pressure are stabilized near the target values by controlling the operation frequency thereof. If the target high pressure value and low pressure value are not near the target only by the operation frequency control, the compressor 1b is operated or stopped. For this reason, the compressor 1b may be selectively stopped even when the compressor 1a is operating.

As described above, the refrigerant outlet 41b of the refrigerant outlet pipe 4b connected to the compressor 1b, which can be stopped, is connected to the refrigerant outlet 41a of the refrigerant outlet pipe 4a connected to the compressor 1a which is always operated. By arranging the compressor 1a farther from the inflow pipe 2 than the outlet 41a, when the compressor 1a is operating and the compressor 1b is stopped, the refrigerant that has entered the accumulator 2 from the refrigerant inflow pipe 3 always flows through the refrigerant. It flows only to the outlet 41a and does not reach the refrigerant outlet 41b. Therefore, while the compressor 1b is stopped, the refrigerant refrigerant does not enter the refrigerant outflow pipe 4b, and the liquid refrigerant does not accumulate therein.
The problem that the compressor is damaged by sucking a large amount of liquid at the time of starting can be avoided.

Embodiment 4 of the Invention FIG. 9 shows an accumulator according to Embodiment 4 of the present invention in a vertical section along the cylinder center direction, and FIG. 10 shows the accumulator in FIG. 9 in a section perpendicular to the cylinder center direction. is there. The components in the figure are the same as those shown in FIG. 1 of the first embodiment with the same reference numerals, but since a partition plate 16 is added, this will be described. The partition plate 16 divides the inside of the accumulator 2 into an inflow chamber 2 having a refrigerant inlet 31.
a and an outflow chamber 2b having refrigerant outlets 41a and 41b. Further, the partition plate 16 is located above the accumulator 2, and a first communication hole 17 is formed below the partition plate 16. As shown in FIG. 9, the lower end of the partition plate 16 extends below the straight lines L1 and L2 connecting the refrigerant inlet 31 and the refrigerant outlets 41a and 41b. The inflow chamber 2a and the outflow chamber 2b communicate with each other at a position lower than the straight lines L1 and L2.

With the above configuration, for example, the refrigerant flowing from the refrigerant inlet 31 geometrically connects the refrigerant inlet 31 and the refrigerant outlet 41a to the closest path (L
1), it is impossible to flow along the first communication hole 1
In order to pass through No. 7, the flow will always follow a curved path. Therefore, even when the liquid refrigerant is mixed with the refrigerant from the refrigerant inlet 31, the liquid refrigerant jumps directly into the refrigerant outlets 41 a, 41 b and flows out of the refrigerant outlet pipes 4 a, 4 b
The possibility of being sucked into the interior is reduced, the gas-liquid separation function of the accumulator 2 can be improved, and the reliability of the air conditioner can be improved.

Embodiment 5 of the Invention FIG. 11 shows an accumulator according to Embodiment 5 of the present invention in a vertical cross section along the cylinder center direction, and FIG. 12 shows the accumulator in FIG. 11 in a cross section perpendicular to the cylinder center direction. . The components in the figure are the same as those shown in FIG. 9 of the fourth embodiment with the same reference numerals, but the partition plate 16 and the oil return pipes 5a, 5
Since b is different, this will be described. That is, the third communication hole 18 is formed in the partition plate 16 instead of the first communication hole 17. The lower end of the third communication hole 18 is at a predetermined height h3 from the bottom in the accumulator 2, and therefore, the third communication hole 18 is connected to the accumulator 2.
The inflow chamber 2a and the outflow chamber 2b communicate with each other at a position higher than the bottom of the inflow chamber. The upper end of the third communication hole 18 is located below a straight line L1 connecting the refrigerant inlet 31 and the refrigerant outlet 41a. One end of each of the oil return pipes 5a and 5b is connected to the bottom of the inflow chamber 2a which is partitioned by the partition plate 16.

With the above configuration, the mixed liquid of the liquid refrigerant and the lubricating oil flowing from the refrigerant inlet 31 accumulates in the inflow chamber 2a until the liquid level reaches the height h3. The oil returns from the oil return pipes 5a and 5b to the compressors 1a and 1b through the refrigerant outflow pipes 4a and 4b. Therefore, even if the accumulator 2 is enlarged to accommodate a plurality of compressors,
By concentrating and storing the mixed liquid containing the lubricating oil in the inflow chamber 2a, the liquid level can be increased as compared with the case where the mixed liquid is stored in the entire accumulator 2 on average. As a result, the amount of oil returned can be increased due to an increase in the liquid column pressure, and compressor failure due to depletion of lubricating oil can be avoided. When the liquid level exceeds h3, the liquid mixture flows to the outflow chamber 2b through the third communication hole 18, so that the liquid level does not rise more than necessary and does not reach an excessive liquid return amount. Therefore, liquid back which is not preferable for the compressor can be avoided.

The upper end of the third communication hole 18 is located below the straight line L1 connecting the refrigerant inlet 31 and the refrigerant outlet 41a, and the flow of the refrigerant in the accumulator 2 is geometrically changed. Since the closest route (L1) connecting the inflow port 31 and the refrigerant outflow port 41a can be prevented, even when the gaseous refrigerant from the refrigerant inflow port 31 is mixed with the liquid refrigerant, the liquid refrigerant directly flows out of the refrigerant. The possibility of being sucked into the pipes 4a and 4b is reduced, the gas-liquid separation function of the accumulator 2 can be improved, and the reliability of the air conditioner can be increased.

Embodiment 6 of the Invention FIG. 13A shows an accumulator according to Embodiment 6 of the present invention in a cross section perpendicular to the cylinder center direction, and FIG.
FIG. 2A shows the accumulator in a horizontal section. Although the components in the figure are substantially the same as those shown in FIG. 11 of the fifth embodiment with the same reference numerals, the partition plate 16 has a second communication hole 19 instead of the third communication hole 18. Is formed. The center line X of the refrigerant inflow pipe 3, the center line Y of the second communication hole 19 on the partition plate 16, and the refrigerant outflow pipe 4
The center lines Z of the a and 4b are disposed at positions shifted horizontally from each other. Therefore, the second communication hole 19 is formed by a straight line connecting the refrigerant inlet 31 and the refrigerant outlets 41a and 41b. Inflow chamber 2 at a position shifted in the horizontal direction parallel to
a and the outflow chamber 2b.

With the above construction, there is no longer a linear path through which the liquid refrigerant from the refrigerant inflow pipe 3 flows directly into the refrigerant outflow pipes 4a and 4b, and the flow of the refrigerant is bent to improve the gas-liquid separation effect. However, since damage to the compressor is also avoided, the reliability of the air conditioner is sufficiently improved.

Embodiment 7 of the Invention FIG. 14 shows an accumulator according to Embodiment 7 of the present invention in a longitudinal section along the cylinder center direction, and the schematic configuration thereof is that of Embodiment 5
11 is similar to that of FIG. 11 except that one end is opened in the accumulator 2 and the other end is connected to the accumulator 2.
A liquid level detection pipe 21 connected to the refrigerant outflow pipe 4a outside; and a heater 2 for heating the liquid level detection pipe 21 outside the accumulator 2
2 and a temperature sensor 23 for detecting the pipe temperature of the liquid level detection pipe 21 up to the junction with the refrigerant outflow pipe 4a on the downstream side of the heater 22. Reference numeral 20 denotes a fourth communication hole 20 formed in the partition plate 16. The liquid level detection tube 2
Reference numeral 1 denotes an opening on the refrigerant outlet 41a, 41b side of the partition plate 16 (that is, in the outlet chamber 2b). The structure including the liquid level detecting tube 21, the heater 22, and the temperature sensor 23 is an example of the liquid level detecting means according to the present invention.

Next, the operation will be described. When the height of the liquid level in the accumulator 2 is less than the height h4 to the upper end opening of the liquid level detection tube 21, almost all of the gas refrigerant flows in the liquid level detection tube 21. When the liquid level detection pipe 21 is heated by the heater 22 in this state, the gas refrigerant in the liquid level detection pipe 21 immediately becomes overheated, and the temperature sensor 23 detects a high temperature (the temperature of the refrigerant overheated from the saturation temperature). Will be. On the other hand, when the liquid level in the accumulator 2 becomes higher than h4, the liquid refrigerant flows through the liquid level detection tube 21. In the case of a liquid refrigerant, the liquid level detecting tube 2
All of the refrigerant in 1 is not vaporized, and is in a low-pressure two-phase state at the position of the temperature sensor 23. Therefore, the temperature sensor 23
Will detect the low temperature of the low pressure saturation temperature.

As described above, since the temperature detected by the temperature sensor 23 differs depending on the height of the liquid level in the accumulator 2, it is determined whether the liquid level in the accumulator 2 has reached a predetermined height based on the detected temperature. It becomes possible to detect. Therefore, if a control device (not shown) for operating / stopping the compressor based on the detection result is provided, for example, the liquid level in the accumulator 2 excessively rises, and finally, the liquid flows into the refrigerant outflow pipes 4a and 4b. It is possible to stop the compressor before it is sucked to avoid damage to the compressor due to liquid compression.

Further, in the above, since the rapid flow of the refrigerant from the refrigerant inlet 31 is alleviated by the partition plate 16, the liquid level in the outflow chamber 2b is higher than the liquid level in the inflow chamber 2a. It will be less stable. Therefore,
The detection accuracy of the liquid level is improved as compared with the case where the partition plate 16 is not provided, and a detection error occurs due to the rise of the liquid level due to the liquid refrigerant flowing from the refrigerant inflow pipe 3 so that the operation of the compressor is unnecessarily stopped. The situation can be avoided, and the performance of the air conditioner can be stably exhibited.

Embodiment 8 of the Invention FIG. 15 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 8 of the present invention, and FIG. 16 is a view showing an accumulator in the air-conditioning apparatus of FIG. In FIG.
1a and 1b are compressors, 2 is an accumulator, 3 is a refrigerant inflow pipe to the accumulator 2, 4a and 4b are refrigerant outflow pipes for returning refrigerant from the accumulator 2 to the compressors 1a and 1b, and 5a and 5b are from the accumulator 2. Refrigerant outflow pipe 4
a return pipe for returning lubricating oil to a and 4b, 7 is a four-way switching valve, 8 is a heat source side heat exchanger, 9a and 9b are flow control devices,
10a and 10b are use side heat exchangers, 11 is a high pressure sensor, 12 is a low pressure sensor, 24a and 24b are auxiliary oil return pipes for returning lubricating oil from the accumulator 2 to the refrigerant outflow pipes 4a and 4b, and 25 is compression. An oil separator 26 for collecting the lubricating oil discharged from the machine, and an oil return pipe 26 for returning the lubricating oil collected by the oil separator to the accumulator 2.

In FIG. 16, reference numeral 16 denotes a partition plate for partitioning the accumulator 2 into an inflow chamber 2a and an outflow chamber 2b.
21 is a liquid level detection tube, 22 is a heater, 23 is a temperature sensor,
Reference numeral 27 denotes a sub-partition plate for partitioning the space 2c in which the sub-oil return pipes 24a and 24b and the oil return pipe 26 open from the outflow chamber 2b.
Is a sub-communication hole formed in the sub-partitioning plate and communicating the outflow chamber 2b and the space 2c.

As shown in FIG. 17, the partition plate 16 is provided with two fifth communication holes 29 at positions vertically over the horizontal center line.

Next, the movement of the refrigerant during cooling will be described with reference to FIG. The high-temperature and high-pressure gas refrigerant discharged from the compressors 1a and 1b reaches the heat source side heat exchanger 8 via the oil separator 25 and the four-way switching valve 7. Here, the refrigerant condenses and becomes a high-pressure liquid refrigerant. Thereafter, the pressure is reduced by the flow control devices 9a and 9b, and evaporates in the use side heat exchangers 10a and 10b. The low-pressure refrigerant again enters the accumulator 2 through the refrigerant inflow pipe 3 via the four-way switching valve 7 and the refrigerant outflow pipes 4a and 4b through the fifth communication holes 29 of the partition plate 16, and the compressor 1a , 1b.

Next, the operation of the refrigerant during heating will be described. At the time of heating, the high-temperature and high-pressure gas refrigerant discharged from the compressors 1a and 1b passes through the oil separator 25 and the four-way switching valve 7 to use the heat exchanger 10 on the utilization side.
a, 10b. Here, after being condensed to become a liquid refrigerant, the pressure is reduced by the flow control devices 9a and 9b to become a gas-liquid two-phase refrigerant. Thereafter, it evaporates in the heat source side heat exchanger 8, returns to the accumulator 2 via the four-way switching valve 7, and returns to the compressors 1a and 1b in the same manner as in cooling.

As described above, during cooling, the use-side heat exchanger 1
In heating 0a and 10b, the heat source side heat exchanger 8 acts as an evaporator during heating, but a part of the refrigerant does not completely evaporate and reaches the accumulator 2 in a liquid state. The flow of the refrigerant flowing into the accumulator 2 from the refrigerant inflow pipe 3 tends to be bent by the partition plate 16 before flowing out of the refrigerant outflow pipes 4a and 4b. Most of the gas refrigerant, which does not bend and collides with the inner surface of the accumulator 2 or the partition plate 16 and drops, flows into the outflow pipes 4a and 4b, and the liquid refrigerant stays at the bottom in the accumulator 2. Thus, gas-liquid separation is performed in the accumulator 2 and the compressors 1a,
This prevents the liquid refrigerant from returning directly to 1b and causing a problem of liquid compression.

Next, the flow of the lubricating oil will be described. A small amount of lubricating oil is always discharged from the compressors 1a and 1b together with the refrigerant. Most of the lubricating oil is captured by the oil separator 25. The lubricating oil captured by the oil separator 25 flows through the oil return pipe 26 into the space 2c of the accumulator 2. Since the space 2c is isolated from the outflow chamber 2b by the sub-partition plate 27, it does not mix with the liquid refrigerant stored in the inflow chamber 2a and the outflow chamber 2b, so that the lubricating oil stored here has a high concentration. ing. The lubricating oil accumulated in the space 2c is removed from the auxiliary oil return pipe 24 provided at the bottom thereof.
a, and returns to the compressors 1a and 1b.

The oil separator 25 separates most of the lubricating oil, but the lubricating oil that could not be separated still flows to the four-way switching valve 7 together with the refrigerant. And regardless of cooling / heating,
Eventually, it returns to the accumulator 2, where it is separated into gas and liquid and stays with the liquid refrigerant at the bottom of the inflow chamber 2a and the inflow chamber 2b of the accumulator 2. Since the liquid refrigerant exists, the lubricating oil concentration in the inflow chamber 2a and the outflow chamber 2b becomes lower than the lubricating oil concentration in the space 2c. Thus, the inflow chamber 2a,
The lubricating oil retained in the outflow chamber 2b is returned to the oil return pipe 5 together with the liquid refrigerant.
The flow returns to the compressors 1a and 1b via a and 5b.

Further, as shown in FIG. 17, by disposing the lower end of the fifth communication hole 29 at a position separated from the bottom of the accumulator 2 by a predetermined height h5, the liquid level in the accumulator 2 is low. In this case, the mixed liquid of the refrigerant and the lubricating oil is retained in the inflow chamber 2a, and the liquid level thereof is raised to raise the liquid column pressure to increase the amount of the mixed liquid flowing through the oil return pipes 5a and 5b, that is, the amount of oil returned. When the liquid level rises further, the outflow chamber 2 is discharged through the fifth communication hole 29.
By suppressing the rise of the liquid level by flowing the liquid refrigerant to c, the liquid column pressure is not increased unnecessarily, and the amount of liquid refrigerant flowing along with the lubricating oil through the oil return pipes 5a and 5b can be suppressed.
It is possible to avoid the occurrence of liquid back in a and 1b and damage to the compressor.

The fifth communication hole 29 does not include the horizontal center line of the partition plate 16 as shown in FIG.
As shown in FIG. 8, four fifth communication holes 29 are formed in the partition plate 16 so as to be arranged above and below the horizontal center line of the partition plate 16 and to the left and right of the vertical center line, respectively. However, if the lower end of the hole located at the lower portion is located at the height of h5 from the bottom of the accumulator 2, almost the same effect as in FIG. 17 can be obtained.

In order to increase the gas-liquid separation effect,
As shown in FIG. 19, the partition 30 shown in FIG.
It is also conceivable to provide (an example of the refrigerant direction changing means). That is, the eaves portion 30 covers the outflow chamber 2b side of the four fifth communication holes 29, respectively, and the direction of the opening (indicated by n in the drawing) corresponds to the fifth communication hole 29 and the refrigerant outflow pipe 4
It is formed so as to face a direction different from a straight line (indicated by D1 in the figure) connecting the refrigerant outlets 41a and 41b of the a and 4b. Therefore, when the refrigerant flowing from the inflow chamber 2a toward the outflow chamber 2b passes through the fifth communication hole 29, the eaves 3
Since the direction is greatly changed by 0, the liquid refrigerant is less likely to be sucked into the refrigerant outflow amounts 4a and 4b, and the gas-liquid separation performance of the accumulator 2 is improved, so that the reliability of the air conditioner can be improved.

The eave portion 30 may be constructed by attaching another member to the partition plate 16. Further, when the fifth communication hole 29 is punched and formed in the partition plate 16, the eave portion 30 is not completely punched out.
A part may remain connected to the partition plate 16 to form an eaves shape. Further, the refrigerant direction changing means of the present invention is not limited to the above-mentioned eaves portion, and if the direction of the refrigerant passing through the fifth communication holes 29 can be changed, for example, the outflow chamber of each fifth communication hole 29 A configuration in which a downwardly or laterally curved tube is attached to the outlet on the 2b side may be employed.

[0058]

According to the air conditioner of the present invention, the lubricating oil accumulated at the bottom of the accumulator can be supplied to the operating compressor through the oil return pipe and the refrigerant outlet pipe. In addition, even when some or all of the plurality of compressors are stopped, the inside of the refrigerant outflow pipe connected to the stopped compressor is not filled with the liquid refrigerant in the accumulator. Damage to the compressor due to liquid compression can be prevented.

When only a part of the compressor is operated, the refrigerant flowing from the refrigerant inlet into the accumulator is made to jump over the refrigerant outlet of the refrigerant outlet pipe connected to the stopped compressor. The refrigerant does not flow to the refrigerant outlet of the refrigerant outlet pipe connected to the operating compressor. Therefore, a part of the liquid refrigerant droplets from the refrigerant inlet does not enter the refrigerant outlet pipe connected to the stopped compressor and accumulate, so that the compressor is damaged due to the liquid compression at the time of starting the compressor. Can be prevented.

Further, since it is not necessary to bend the thick refrigerant outflow pipe in the direction of the compressor as in the case where the refrigerant outflow pipe is connected to the bottom of the accumulator, the space below the accumulator can be reduced, and the installation position of the accumulator can be lowered. In addition, since the degree of freedom in piping design is increased, the size of the air conditioner can be reduced.

Further, the refrigerant from the refrigerant inlet to the refrigerant outlet always follows a curved path to pass through the first communication hole, and the liquid refrigerant is mixed with the gas refrigerant from the refrigerant inlet. Also in this case, the possibility that the liquid refrigerant jumps directly into the refrigerant outlet and is sucked into the refrigerant outlet pipe is reduced. Therefore, the gas-liquid separation performance of the accumulator can be improved, and damage to the compressor due to liquid compression can be prevented.

In addition, the refrigerant from the refrigerant inlet to the refrigerant outlet always follows a curved path to pass through the second communication hole, and the liquid refrigerant is mixed with the gas refrigerant from the refrigerant inlet. Also in this case, the possibility that the liquid refrigerant jumps directly into the refrigerant outlet and is sucked into the refrigerant outlet pipe is reduced. Therefore, the gas-liquid separation performance of the accumulator can be improved, and damage to the compressor due to liquid compression can be prevented.

Since the third communication hole is located at a position higher than the bottom of the accumulator, the liquid surface of the liquid refrigerant and the lubricating oil mixed with the gas refrigerant and flowing from the refrigerant inlet into the inflow chamber has the third level. Until it reaches the communication hole, it collects intensively in the inflow chamber. Therefore, the liquid level in the inflow chamber becomes higher than the liquid level in the outflow chamber, and the liquid column pressure rises, so that the amount of oil returned to the compressor through the oil return pipe connected to the bottom of the inflow chamber increases. . Therefore, for example, even if the accumulator is increased in size to accommodate a plurality of compressors, damage to the compressor due to depletion of the lubricating oil can be prevented.
When the liquid level in the inflow chamber reaches the third communication hole, the liquid flows to the outflow chamber through the third communication hole, so that the liquid level in the inflow chamber becomes excessively high and the liquid column pressure becomes unnecessarily high. There is no rise and the liquid back state unfavorable for the compressor can be avoided.

Further, the rapid flow of the refrigerant from the refrigerant inlet is alleviated by the partition plate, and the liquid level in the outflow chamber becomes stable with little waving, so that the liquid level detecting means provided in the outflow chamber is used to detect the inside of the accumulator. Can be detected with high precision, and a situation in which the compressor is unnecessarily stopped due to a detection error can be avoided.

The refrigerant flowing from the refrigerant inlet to the refrigerant outlet is changed in flow direction by the refrigerant direction changing means when passing through the fifth communication hole. Even when the refrigerant is mixed, the possibility that the liquid refrigerant jumps directly into the refrigerant outlet and is sucked into the refrigerant outflow pipe is reduced. Therefore, the gas-liquid separation performance of the accumulator can be improved, and damage to the compressor due to liquid compression can be prevented.

[Brief description of the drawings]

FIG. 1 is a side view partially showing a main part of an air conditioner according to Embodiment 1 of the present invention in cross section.

FIG. 2 is a cross-sectional view showing the accumulator according to Embodiment 1 of the present invention in a cross section perpendicular to the cylinder center direction.

FIG. 3 is a cross-sectional view illustrating an accumulator according to a second embodiment of the present invention in a cross section perpendicular to the cylinder center direction.

FIG. 4 is a cross-sectional view showing another accumulator according to Embodiment 2 of the present invention in a cross section perpendicular to the cylinder center direction.

FIG. 5 is a side view partially showing a main part of an air conditioner according to Embodiment 3 of the present invention in cross section.

FIG. 6 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 3 of the present invention.

FIG. 7 is a control block diagram of the air conditioner of FIG.

FIG. 8 is a control flowchart of the air-conditioning apparatus of FIG. 6;

FIG. 9 is a cross-sectional view showing an accumulator according to a fourth embodiment of the present invention in a vertical cross-section along the direction of the cylinder center.

FIG. 10 is a cross-sectional view showing the accumulator of FIG. 9 in a cross section perpendicular to the cylinder center direction.

FIG. 11 is a cross-sectional view showing an accumulator according to a fifth embodiment of the present invention in a vertical cross-section along the direction of the cylinder center.

FIG. 12 is a cross-sectional view showing the accumulator of FIG. 11 in a cross section perpendicular to the cylinder center direction.

FIG. 13 (a) is a cross-sectional view showing an accumulator according to Embodiment 6 of the present invention in a cross section perpendicular to the cylinder center direction. 13B is a cross-sectional view showing the accumulator of FIG. 13A in a horizontal cross section.

FIG. 14 is a cross-sectional view showing an accumulator according to Embodiment 7 of the present invention in a vertical cross-section along the cylinder center direction.

FIG. 15 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 8 of the present invention.

FIG. 16 is a cross-sectional view showing an accumulator according to an eighth embodiment of the present invention in a vertical cross-section along the direction of the cylinder core.

17 is a cross-sectional view showing the accumulator of FIG. 16 in a cross section perpendicular to the cylinder center direction.

FIG. 18 is a cross-sectional view showing another accumulator according to Embodiment 8 of the present invention in a cross section perpendicular to the cylinder center direction.

FIG. 19 is a schematic explanatory view showing shapes and positional relationships of a partition plate, an eaves portion, and a refrigerant outflow pipe in still another accumulator according to Embodiment 8 of the present invention.

[Explanation of symbols]

1a compressor, 1b compressor, 2 accumulators, 3
Refrigerant inflow pipe, 31 refrigerant inflow port, 4a refrigerant outflow pipe, 4
b refrigerant outlet pipe, 41a refrigerant outlet, 41b refrigerant outlet, 5a oil return pipe, 5b oil return pipe, 16 partition plate, 1
7 1st communication hole, 18 3rd communication hole, 19 2nd communication hole, 20 4th communication hole, 21 liquid level detection pipe, 22
Heater, 23 temperature sensor, 29 fifth communication hole, 30
Eaves (refrigerant direction changing means).

Claims (8)

[Claims] An accumulator to which a refrigerant inflow pipe and a plurality of refrigerant outflow pipes are connected, and a plurality of compressors respectively connected to the accumulator via the refrigerant outflow pipe, wherein a refrigerant flow in the refrigerant outflow pipe is provided. An air conditioner having an outlet disposed at a position higher than the bottom of the accumulator, wherein one end is connected to the bottom of the accumulator, and the other end is connected to the plurality of refrigerant outlet pipes at a position higher than the bottom of the accumulator. An air conditioner comprising a plurality of oil return pipes. 2. A control device for controlling the number of operating compressors, the control device being connected to a compressor that stops when the control device controls only a part of the compressors. 2. The air conditioner according to claim 1, wherein the refrigerant outlet of the refrigerant outlet pipe is disposed at a position horizontally separated from the refrigerant inlet of the other refrigerant outlet pipe. 3. 3. The accumulator is formed in a laterally substantially cylindrical shape, and a refrigerant outlet pipe is connected to a peripheral wall at a position circumferentially displaced from a bottom of the accumulator.
Item 3. The air conditioner according to item 2 or 2. 4. A partition plate for partitioning the interior of the accumulator into an inflow chamber having a refrigerant inlet and an outflow chamber having a refrigerant outlet, and a straight line connecting the refrigerant inlet and the refrigerant outlet to the partition plate. The air conditioner according to any one of claims 1 to 3, wherein a first communication hole communicating the inflow chamber and the outflow chamber at a lower position than the first communication hole is formed. 5. A partition plate for partitioning the interior of the accumulator into an inflow chamber having a refrigerant inlet and an outflow chamber having a refrigerant outlet, and a straight line connecting the refrigerant inlet and the refrigerant outlet to the partition plate. The air conditioner according to any one of claims 1 to 3, wherein a first communication hole that communicates the inflow chamber and the outflow chamber is formed at a position shifted in a horizontal direction parallel to the partition plate. apparatus. 6. A partition plate for partitioning the inside of the accumulator into an inflow chamber having a refrigerant inlet and an outflow chamber having a refrigerant outlet, wherein the partition plate is provided at a position higher than the bottom of the accumulator. The air conditioner according to any one of claims 1 to 3, wherein a third communication hole communicating with the outflow chamber is formed, and one end of an oil return pipe is connected to a bottom of the inflow chamber. 7. A partition plate for partitioning the inside of the accumulator into an inflow chamber having a refrigerant inlet and an outflow chamber having a refrigerant outlet, and a fourth connecting the partition with the inflow chamber and the outflow chamber. The air conditioner according to any one of claims 1 to 3, wherein the communication hole is formed, and the outflow chamber is provided with a liquid level detecting means for detecting a liquid level of an accumulator surface. 8. A partition plate for dividing the inside of the accumulator into an inflow chamber having a refrigerant inlet and an outflow chamber having a refrigerant outlet, and a fifth plate connecting the inflow chamber and the outflow chamber to the partition plate. The air conditioner according to any one of claims 1 to 3, further comprising: a refrigerant direction changing unit that forms the communication hole of (i) and changes a flow direction of the refrigerant passing through the fifth communication hole.