JPH062962A - Air conditioner - Google Patents

Abstract

PURPOSE:To always hold a temperature change of a suction tube in a suitable range and to prevent returning of oil at the time of starting by controlling a switching valve provided in an oil return tube of an accumulator based on a temperature difference across a connector of the circuit to the suction tube of the compressor. CONSTITUTION:An air conditioner comprises an accumulator 9A arranged at a suction side of a compressor 1 and an oil separator 2 arranged at a discharge side of the compressor 1. Oil separated by the separator 2 is returned to a suction tube 10 of the compressor 1 via an oil return tube 2d. In this case, the accumulator 9A connects an oil return tube 9c having a switching valve 13 and a flow regulating tube 14 from a body bottom to an outlet tube 9b. On the other hand, temperatures across a connector of the tube 2d to the tube 10 are respectively detected by sensors 11 and 12. The valve 13 is controlled by control means 15 based on a temperature difference across the connector. Thus, an internal temperature of the compressor 1 can be suitably held.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 3 shows a refrigerant circuit of a conventional air conditioner. In the figure, a conventional air conditioner includes a compressor 1, an oil separator 2, an oil separator inlet pipe 2a, an oil separator 2b, an oil separator outlet pipe 2c, an oil separator oil return pipe 2d, a flow rate adjusting pipe 2e, and a four-way valve 3. , Indoor heat exchanger 4, expansion mechanism 5, check valve 6, expansion mechanism 7, outdoor heat exchanger 8, accumulator 9, accumulator inlet pipe 9
a, a U-shaped pipe 9d of the accumulator, an oil return hole 9e of the accumulator, and a suction pipe 10. During the cooling operation, the refrigerant gas containing the high temperature and high pressure refrigeration oil discharged from the compressor 1 enters the oil separator 2 through the oil separator inlet pipe 2a. Refrigerating machine oil is separated by the oil separating portion 2b and is accumulated on the bottom of the oil separator 2. The gas refrigerant enters the outdoor heat exchanger 8 from the oil separator outlet pipe 2c through the four-way valve 3. Here, heat is condensed and becomes a liquid refrigerant, and the check valve 6
And enters the expansion mechanism 5. Here, the pressure is reduced to form a low-pressure two-phase refrigerant, which enters the indoor heat exchanger 4. Here, it endothermically evaporates, passes through the four-way valve 3, and enters the accumulator 9 from the inlet pipe 9a of the accumulator. Here, the non-evaporated refrigerant is separated and collected at the bottom. The gas refrigerant passes through the U-shaped pipe 9d and the suction pipe 10
Is sucked into the compressor 1 and compressed. On the other hand, the liquid refrigerant containing the refrigerating machine oil accumulated at the bottom of the accumulator 9 is sucked into the U-shaped pipe 9d through the oil return hole 9e, and is sucked into the compressor 1 through the suction pipe 10 of the compressor 1 for lubrication. To serve. On the other hand, the refrigerating machine oil accumulated at the bottom of the oil separator 2 merges with the suction pipe 10 of the compressor 1 through the oil return pipe 2d, the flow rate adjusting pipe 2e, and is sucked into the compressor 1. In this way, the oil returning function of the oil separator 2 and the accumulator 9 prevents the refrigerating machine oil of the compressor 1 from becoming insufficient.

[0003]

The above conventional air conditioner has the following problems to be solved.

That is, in the conventional air conditioner, since the oil return hole 9e of the accumulator 9 has a constant size, the amount of the liquid refrigerant returning from the oil return hole 9e changes little. On the other hand, the refrigerating machine oil separated by the oil separator 2 is high in temperature, which is almost close to the discharge gas temperature. The liquid refrigerant from the accumulator 9 and the refrigerating machine oil from the oil separator 2 are sucked into the suction pipe 1
It merges at 0 and is sucked into the compressor 1. For this reason, since the discharge gas temperature is high during high load operation, the temperature of the suction pipe 10 rises and the compressor 1 abnormally overheats. Further, when the load is low, the discharge gas temperature is low, the temperature of the suction pipe 10 is lowered, and the internal temperature of the compressor 1 is excessively lowered.

On the other hand, when the compressor 1 is stopped, the liquid refrigerant in the accumulator 9 enters into the U-shaped pipe 9d of the accumulator through the oil return hole 9e below the accumulator 9, so that the accumulator is started when the compressor 1 is started. The liquid refrigerant accumulated in the U-shaped pipe 9d is sucked into the compressor 1 to cause a failure due to liquid compression, and the refrigerating machine oil in the compressor 1 is diluted and seized.

In order to solve the above problems, it is an object of the present invention to provide an air conditioner that keeps the temperature change range of the suction pipe within a predetermined value and does not cause liquid return at the time of startup.

[0007]

As a means for solving the above problems, the present invention provides an accumulator on the suction side of a compressor, an oil separator on the discharge side of the compressor, and an oil separated by the oil separator. In the air conditioner in which the oil is returned to the compressor suction pipe through the oil return circuit, the accumulator is configured such that an oil return pipe having an opening / closing valve and a flow rate adjusting pipe is connected to the outlet pipe of the accumulator from the bottom of the accumulator. At the same time, the air conditioner is provided with a control means for detecting the temperature before and after the connecting portion of the oil return circuit to the compressor suction pipe of the oil return circuit and opening and closing the temperature according to the temperature difference. It is the one we are trying to provide.

[0008]

Since the present invention is constructed as described above, it has the following actions.

That is, the accumulator has a constitution in which an oil return pipe having an opening / closing valve and a flow rate adjusting pipe is connected to the outlet pipe of the accumulator from the bottom, and the opening / closing valve is
The temperature of the front and rear of the connection of the oil return circuit to the compressor suction pipe is detected and the control means opens and closes according to the temperature difference. If it passes through the pipe and joins the suction pipe of the compressor, the temperature of the suction pipe after merging rises, and if there is a temperature difference with the temperature of the suction pipe before merging, this temperature difference is detected by the sensor and The control means controls the on-off valve so that the liquid refrigerant flows from the bottom of the accumulator to the suction pipe through the on-off valve and the flow rate adjusting pipe.

The flow rate adjusting tubes each have a predetermined flow rate resistance. As a result, excessive temperature rise and temperature drop of the compressor are suppressed.

Further, while the compressor is stopped, the on-off valve is closed to prevent the liquid refrigerant in the accumulator from flowing into the accumulator outlet pipe. When the compressor is started, it will be opened after a predetermined time.
This prevents the liquid from returning when the compressor is started.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first and second embodiments of the present invention will be described with reference to FIGS. The same components as those of the conventional example are designated by the same reference numerals, and the description thereof will be omitted unless necessary.

(First Embodiment) A first embodiment will be described with reference to FIG. FIG. 1 is a refrigerant circuit diagram of the air conditioner of this embodiment,
In the figure, in order to facilitate understanding of the present embodiment, the difference from the conventional example will be described. 9A is an accumulator, which is a conventional U-shaped tube 9d compared to the conventional accumulator 9 (FIG. 3). The oil return hole 9e and the oil return hole 9e are eliminated. Instead, in the present embodiment, the oil return pipe 9c and the outlet pipe 9b are provided at the bottom of the accumulator 9A, and the opening / closing valve 13 and the flow rate adjusting pipe 14 are provided from the oil return pipe 9c. Are connected in series downstream of the outlet pipe 9b. Oil return pipe 9c
Is provided near the bottom of the accumulator 9A, and the flow rate adjusting pipe 14 is provided with a predetermined flow rate resistance. The intake pipe 10 of the compressor 1 is provided with a temperature sensor 12 on the front side where the flow rate adjusting pipe 2e joins and a temperature sensor 11 on the rear side, and the on-off valve 1 provided separately.
It is hard-wired to the control means 15 for 3 control. Other configurations are similar to those of the conventional example of FIG.

Next, the operation of the above configuration will be described.

In FIG. 1, the high temperature refrigerating machine oil in the oil separator 2 merges with the suction pipe 10 of the compressor 1 through the oil return pipe 2d and the flow rate adjusting pipe 2e, is sucked into the compressor 1 and used for lubrication. On the other hand, since the temperature of the suction pipe 10 after the merging increases, a temperature difference from the temperature of the suction pipe 10 before the merging occurs.
This is detected by the temperature sensors 11 and 12, and the control means 15
To enter. The control means 15 controls the on-off valve 13 so that a predetermined temperature difference is obtained by this input value, and the liquid refrigerant containing the refrigerating machine oil in the accumulator 9A is adjusted from the bottom of the accumulator 9A to the oil return pipe 9c, the on-off valve 13, the flow rate adjustment. It passes through the pipe 14 and joins the outlet pipe 9b of the accumulator. Then, it is sucked into the compressor 1 through the suction pipe 10. When the temperature difference is larger than a predetermined value, the control means 15 opens the on-off valve 13, and when it is small, it is closed.

On the other hand, while the compressor 1 is stopped, the control means 15
Closes the on-off valve 13 to prevent the liquid in the accumulator 9A from flowing into the outlet pipe 9b of the accumulator. When the compressor 1 is started, the on-off valve 13 is opened after a predetermined time and the normal operation is performed. This prevents the liquid from returning to the compressor 1 at startup.

As described above, according to the first embodiment, the oil return pipe 2d from the oil separator 2 and the suction pipe 1 are in operation.
When the temperature in the vicinity of the point of merging with 0 exceeds a predetermined value before and after merging, the control means 15 to which the temperature (difference) is input by the temperature sensors 11 and 12 controls the opening / closing valve 13 to open / close the temperature. Has an advantage that the compressor 1 can always maintain normal operation regardless of the operating load.

During the stop, the control means 15 controls the open / close valve 13
The liquid in the accumulator 9A is closed by the outlet pipe 9b.
Since there is no return to the compressor 1 during startup and there is no return of liquid to the compressor 1, there is the advantage of eliminating troubles due to liquid compression and problems such as seizure due to dilution of refrigerating machine oil.

(Second Embodiment) A second embodiment will be described with reference to FIG. FIG. 2 is a view of the vicinity of the accumulator 9A of the present embodiment. In the first embodiment, the opening / closing valve 13 and the flow rate adjusting pipe 14 are each 1
In contrast to the first embodiment, the present embodiment is different only in that two pieces are provided in parallel, and the other points are the same as in the first embodiment.

That is, in FIG. 2, 13a and 13b are on-off valves, 14a and 14b are flow rate adjusting pipes, and the on-off valve 13a and the flow rate adjusting pipe 14a are connected in series from the oil return pipe 9c to the outlet pipe 9
It is connected to the downstream part of b and the opening / closing valve 1 is arranged in parallel with it.
3b and the flow rate adjusting pipe 14b are connected in series. The on-off valves 13a and 13b are hard-wired to the control means 15 (not shown).

Next, the operation of the above configuration will be described.

As in the first embodiment, the control means 15 opens and closes the on-off valves 13a and 13b to open the compressor 1
Widely adjust the flow rate of the liquid refrigerant containing the refrigerating machine oil that is drawn into the.

On the other hand, while the compressor 1 is stopped, the on-off valve 13
By closing a and 13b, the liquid in the accumulator 9A is prevented from flowing into the accumulator outlet pipe 9b. When the compressor 1 is started, the on-off valves 13a and 13b are opened after a predetermined time, and normal operation is performed. This prevents the liquid from returning to the compressor 1 at startup.

In the case of this embodiment, there is an advantage that the adjustment range of the liquid flow rate is wide.

[0025]

Since the present invention is constructed as described above, it has the following effects.

That is, in the air conditioner of the present invention, when the temperature of the suction pipe of the compressor rises due to the oil return from the oil separator, the temperature difference before and after the merging of the oil return on the suction pipe is automatically detected, To adjust the amount of liquid returning from the accumulator to the compressor so that the temperature difference is appropriate, maintain the compressor internal temperature appropriately from high load operation with high discharge gas temperature to low load with low discharge gas temperature. You can

On the other hand, when the compressor is stopped, the above-mentioned temperature difference does not occur, so the on-off valve at the outlet of the accumulator oil return pipe is closed. Therefore, there is no liquid returning to the compressor at the time of startup,
This eliminates troubles due to liquid compression and seizure due to dilution of refrigerating machine oil.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner according to a first embodiment of the present invention,

FIG. 2 is a refrigerant circuit diagram of an air conditioner of a second embodiment of the present invention,

FIG. 3 is a refrigerant circuit diagram showing a conventional air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Oil separator 2d Oil return pipe 2e Flow rate adjustment pipe 9A Accumulator 9b Outlet pipe 9c Oil return pipe 10 Suction pipe 11,12 Temperature sensor 13,13a, 13b Open / close valve 14,14a, 14b Flow rate adjustment pipe 15 Control means

Front page continued (72) Inventor Masahiko Sakura 3-1-1 Asahi-cho, Nishibiwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Air-conditioner factory (72) Takashi Ogawa Kuttan, Iwatsuka-cho, Nakamura-ku, Aichi Prefecture No. 1 at 60 Churyo Engineering Co., Ltd.

Claims (1)

[Claims] 1. An accumulator is arranged on the suction side of the compressor, an oil separator is arranged on the discharge side of the compressor, and the oil separated by the oil separator is returned to the compressor suction pipe via an oil return circuit. In the air conditioner described above, the accumulator is configured such that an oil return pipe having an opening / closing valve and a flow rate adjusting pipe is connected to the outlet pipe of the accumulator, and the opening / closing valve is connected to the compressor suction port of the oil return circuit. An air conditioner comprising control means for detecting a temperature before and after a connecting portion to a pipe and opening / closing according to the temperature difference.